Volume 46,Issue 2,2018 Table of Contents
2018, 46(2):215-223.
Abstract:
The effects of microenvironmental conditions on the observations of surface air temperature within a standard observational field are unclear. In this paper, the surface observation data of a parallel observational experiment at Mohe Station in 2010 are analyzed. The conclusions are as follows: (1) The annual mean temperature at Site A (close to a house) was lower than that of the standard observational field (Site B), but the monthly mean temperature in January and June at Site A was higher than that of Site B. (2) Between 06:00 and 17:00 (BJT), and at 21:00, lower temperature occurred at Site A; between 18:00 and 05:00 (except 21:00), however,mean temperature at Site A was higher. (3) Lower temperature was recorded at the nearobstacle site for all times in spring (March to May); summer (June to August) also saw the relatively lower temperature at Site A from 06:00 to 17:00; autumn (September to November) mean temperature at Site A was higher than that of the observational field only at 01:00, 03:00, 19:00, 23:00, and it was lower for other times; winter (December to February) mean temperature at Site A was generally lower from 07:00 to 19:00, but higher from 20:00 to 06:00 at night. In cold season (October to March), the mean temperature at Site A was lower than that of the observation field in both daytime and nighttime; but in the warm season (April to September) mean temperature at Site A was lower only during daytime, and higher during nighttime. (4) Minimum and maximum temperatures were recorded at approximately the same time at points A and B, but the maximum temperature was lower, and the minimum temperature is higher at Site A. (5) In the fog weather condition, the temperature at Site A was mostly higher than that at Site B; snow and rain weathers were generally characterized by a lower temperature at Site A; sunny days were more likely to experience lower temperature at Site A; and fair nights were more likely to see a higher temperature at Site A; fair and calm weather conditions were more often accompanied by higher temperature at Site A relative to Site B. It is therefore obvious that the surface air temperature observations are very sensitive to the microenvironmental change at Mohe Station.
The effects of microenvironmental conditions on the observations of surface air temperature within a standard observational field are unclear. In this paper, the surface observation data of a parallel observational experiment at Mohe Station in 2010 are analyzed. The conclusions are as follows: (1) The annual mean temperature at Site A (close to a house) was lower than that of the standard observational field (Site B), but the monthly mean temperature in January and June at Site A was higher than that of Site B. (2) Between 06:00 and 17:00 (BJT), and at 21:00, lower temperature occurred at Site A; between 18:00 and 05:00 (except 21:00), however,mean temperature at Site A was higher. (3) Lower temperature was recorded at the nearobstacle site for all times in spring (March to May); summer (June to August) also saw the relatively lower temperature at Site A from 06:00 to 17:00; autumn (September to November) mean temperature at Site A was higher than that of the observational field only at 01:00, 03:00, 19:00, 23:00, and it was lower for other times; winter (December to February) mean temperature at Site A was generally lower from 07:00 to 19:00, but higher from 20:00 to 06:00 at night. In cold season (October to March), the mean temperature at Site A was lower than that of the observation field in both daytime and nighttime; but in the warm season (April to September) mean temperature at Site A was lower only during daytime, and higher during nighttime. (4) Minimum and maximum temperatures were recorded at approximately the same time at points A and B, but the maximum temperature was lower, and the minimum temperature is higher at Site A. (5) In the fog weather condition, the temperature at Site A was mostly higher than that at Site B; snow and rain weathers were generally characterized by a lower temperature at Site A; sunny days were more likely to experience lower temperature at Site A; and fair nights were more likely to see a higher temperature at Site A; fair and calm weather conditions were more often accompanied by higher temperature at Site A relative to Site B. It is therefore obvious that the surface air temperature observations are very sensitive to the microenvironmental change at Mohe Station.
2018, 46(2):224-228.
Abstract:
Based on the results of the basic data construction radiation (Metadata Set of Radiation Stations), the metrological performance parameters of the national operational total radiation meters from 1990 to 2012 are collected and analyzed. The stability of total radiation meters at national radiation observation stations is analyzed statistically, and the results show that the stability of 561% domestic total radiation meters used in the operational observation of China meets the high quality requirements of WMO; 634% meets the good quality requirements; and 768% meets the medium quality requirements; 91% meets the requirements of oneyear stability within 5% of the Total Radiation Meter Metrological Calibration Regulation of China; 948% meets the requirements of 2year stability within 8%. The stability of China’s domestic total radiation meters basically meets the requirements, and its longterm stability is good. At the same time, a new radiation metadata set of radiation observation stations, which has marked the obvious errors and questions and includes the statistical analysis results of the total radiation sensitivity, is formed. It can be used as a reference for the application and quality evaluation of national radiation data.
Based on the results of the basic data construction radiation (Metadata Set of Radiation Stations), the metrological performance parameters of the national operational total radiation meters from 1990 to 2012 are collected and analyzed. The stability of total radiation meters at national radiation observation stations is analyzed statistically, and the results show that the stability of 561% domestic total radiation meters used in the operational observation of China meets the high quality requirements of WMO; 634% meets the good quality requirements; and 768% meets the medium quality requirements; 91% meets the requirements of oneyear stability within 5% of the Total Radiation Meter Metrological Calibration Regulation of China; 948% meets the requirements of 2year stability within 8%. The stability of China’s domestic total radiation meters basically meets the requirements, and its longterm stability is good. At the same time, a new radiation metadata set of radiation observation stations, which has marked the obvious errors and questions and includes the statistical analysis results of the total radiation sensitivity, is formed. It can be used as a reference for the application and quality evaluation of national radiation data.
2018, 46(2):229-232.
Abstract:
Based on the static threepoint calibration method of wind direction sensors, an evaluating method of measurement uncertainty for calibration results about wind direction sensors of automatic weather stations is introduced. The purpose is to ensure the accurate, reliable and credible observation data of wind direction sensors. In this paper, according to the requirement of the “Calibration Method of Wind Direction of Automatic Meteorological Station” and JJF10591—2012 “Evaluation an Expression of Uncertainty in Measurement,” ten repeated tests are designed for the three calibration points of wind direction, and the sample standard deviation is merged to evaluate the uncertainty of Type A. The uncertainty sources of Type B in the calibration process are analyzed, and the uncertainty of Type B is evaluated. Finally, the extended uncertainty is obtained by combining the uncertainties of Type A and Type B. The evaluation method can provide a reference for evaluating the reliability of calibration results of wind direction sensors.
Based on the static threepoint calibration method of wind direction sensors, an evaluating method of measurement uncertainty for calibration results about wind direction sensors of automatic weather stations is introduced. The purpose is to ensure the accurate, reliable and credible observation data of wind direction sensors. In this paper, according to the requirement of the “Calibration Method of Wind Direction of Automatic Meteorological Station” and JJF10591—2012 “Evaluation an Expression of Uncertainty in Measurement,” ten repeated tests are designed for the three calibration points of wind direction, and the sample standard deviation is merged to evaluate the uncertainty of Type A. The uncertainty sources of Type B in the calibration process are analyzed, and the uncertainty of Type B is evaluated. Finally, the extended uncertainty is obtained by combining the uncertainties of Type A and Type B. The evaluation method can provide a reference for evaluating the reliability of calibration results of wind direction sensors.
2018, 46(2):233-236.
Abstract:
Aiming at the problem of the intricacy of the cables and inconvenient for maintenance and replacement, a wireless ground temperature measurement system is design, which measures the temperature of the fourwire Pt100 platinum resistance by the constant current source, filters and amplifies the temperature signals. The control chip is STC12C5A60S2 with the A/D conversion function integrated inside. The wireless transmission module is a nRF905 chip, which makes the maintenance, replacement and metrological verification of the Pt100 Platinum Resistor much more convenient by transferring data wirelessly. The system uses the LCD1602 to display temperature, which makes the system also be an individual thermometer while transmitting signals wirelessly.
Aiming at the problem of the intricacy of the cables and inconvenient for maintenance and replacement, a wireless ground temperature measurement system is design, which measures the temperature of the fourwire Pt100 platinum resistance by the constant current source, filters and amplifies the temperature signals. The control chip is STC12C5A60S2 with the A/D conversion function integrated inside. The wireless transmission module is a nRF905 chip, which makes the maintenance, replacement and metrological verification of the Pt100 Platinum Resistor much more convenient by transferring data wirelessly. The system uses the LCD1602 to display temperature, which makes the system also be an individual thermometer while transmitting signals wirelessly.
2018, 46(2):237-244.
Abstract:
It is to discuss the processing methods of observation data and to analyze the relation between meteorological elements and observation data by means of the daily measurement from three weighing wireicing automatic observation stations in Ya’an, Aba and Garza, Sichuan Province from February 4 to February 5 The results show that the wavelet filtering method based 〖WTBX〗T〖WTBZ〗value has a good filtering effect for weighing data and it is possible to effectively suppress the noise in the original observation data and retain the characteristic information of the data change. According to the degree of grey comprehensive relation between meteorological factors data and weighing wire icing data, the sequence is: temperature, atmospheric pressure, and wind speed with the relation degree being between 0516 and 0632 The analysis of wind direction rose diagram shows that the growth of ice accretion on the windward side is larger than that in the downwind direction.
It is to discuss the processing methods of observation data and to analyze the relation between meteorological elements and observation data by means of the daily measurement from three weighing wireicing automatic observation stations in Ya’an, Aba and Garza, Sichuan Province from February 4 to February 5 The results show that the wavelet filtering method based 〖WTBX〗T〖WTBZ〗value has a good filtering effect for weighing data and it is possible to effectively suppress the noise in the original observation data and retain the characteristic information of the data change. According to the degree of grey comprehensive relation between meteorological factors data and weighing wire icing data, the sequence is: temperature, atmospheric pressure, and wind speed with the relation degree being between 0516 and 0632 The analysis of wind direction rose diagram shows that the growth of ice accretion on the windward side is larger than that in the downwind direction.
2018, 46(2):245-249.
Abstract:
According to the trend of CPU hybrid architecture for future development in the highperformance computing area, this paper introduces the tuning case of some core segments in the BCC_AGCM model in the Sunway TaihuLight High Performance Computer System. It uses the core segment called quad for example. Through fixing the structure of codes and using OpenACC to instruct the way to execute the program, this segment is transplanted successfully to the platform; the speedingup is realized; and the results passed verification. This case shows that using the OpenACC with little changes in the program can get a speed up. The effectiveness for improving efficiency of the core segment in hybrid architecture is due to the structure of codes, the granularity of cycle parallelism, and address continuity.
According to the trend of CPU hybrid architecture for future development in the highperformance computing area, this paper introduces the tuning case of some core segments in the BCC_AGCM model in the Sunway TaihuLight High Performance Computer System. It uses the core segment called quad for example. Through fixing the structure of codes and using OpenACC to instruct the way to execute the program, this segment is transplanted successfully to the platform; the speedingup is realized; and the results passed verification. This case shows that using the OpenACC with little changes in the program can get a speed up. The effectiveness for improving efficiency of the core segment in hybrid architecture is due to the structure of codes, the granularity of cycle parallelism, and address continuity.
2018, 46(2):250-256.
Abstract:
Any period climatic data statistics for successive years is a common real/quasireal time operational task in meteorological service, which should be supported by the corresponding operational system. In order to improve the efficiency, we optimize the statistic flow and propose a logic decomposition process of the original data in this paper. Taking the relational database Oracle as an example, based on the 65year daily data of 86 national weather stations and the 10year daily data of 2313 regional weather stations, the optimized flow is tested. The results show that, based on the flow before the optimization, the query efficiency decreases with the increasing period span. Conversely, based on the flow after the optimization, the query efficiency maintains a high level, regardless of the span of the period. The optimized flow is applied in the AGRometeorology Operation System of Guangdong Province (AGROS) and plays an important role in improving the system efficiency and optimizing the user experiences. Eventually, the popularization and application of the system in Guangdong Province are further promoted. The optimization flow proposed in this paper has important reference value in the related operational system development in other provinces and national meteorological services.
Any period climatic data statistics for successive years is a common real/quasireal time operational task in meteorological service, which should be supported by the corresponding operational system. In order to improve the efficiency, we optimize the statistic flow and propose a logic decomposition process of the original data in this paper. Taking the relational database Oracle as an example, based on the 65year daily data of 86 national weather stations and the 10year daily data of 2313 regional weather stations, the optimized flow is tested. The results show that, based on the flow before the optimization, the query efficiency decreases with the increasing period span. Conversely, based on the flow after the optimization, the query efficiency maintains a high level, regardless of the span of the period. The optimized flow is applied in the AGRometeorology Operation System of Guangdong Province (AGROS) and plays an important role in improving the system efficiency and optimizing the user experiences. Eventually, the popularization and application of the system in Guangdong Province are further promoted. The optimization flow proposed in this paper has important reference value in the related operational system development in other provinces and national meteorological services.
2018, 46(2):257-261.
Abstract:
The transmission mode and timeliness of single station radar data transmission and interprovincial radar data exchange are analyzed. The influencing factors of radar data transmission timeliness and the improvement measures are given. The results show that by using the single radar data transmission based on ROSE and regional radar synchronization observation, it can be ensured that radar base data and products of the province and the surrounding to reach the forecasters’ desktop within 1 minute. Compared with the interprovincial radar data from the new generation communication system, the regional synchronous observation requires less communication bandwidth and higher time effectiveness. The improvement of the radar data transmission and communication line, and the operation of the integrated use of a variety of realtime transmission modes are introduced, which provides a reference for the improvement of radar data transmission in order to meet the timeliness requirement of meteorological service for radar data.
The transmission mode and timeliness of single station radar data transmission and interprovincial radar data exchange are analyzed. The influencing factors of radar data transmission timeliness and the improvement measures are given. The results show that by using the single radar data transmission based on ROSE and regional radar synchronization observation, it can be ensured that radar base data and products of the province and the surrounding to reach the forecasters’ desktop within 1 minute. Compared with the interprovincial radar data from the new generation communication system, the regional synchronous observation requires less communication bandwidth and higher time effectiveness. The improvement of the radar data transmission and communication line, and the operation of the integrated use of a variety of realtime transmission modes are introduced, which provides a reference for the improvement of radar data transmission in order to meet the timeliness requirement of meteorological service for radar data.
2018, 46(2):262-266.
Abstract:
Using plugin development technology, a public meteorological service platform based on the OSGi.NET plugin framework is developed. According to the three functions of modularization and plugin, serviceoriented architecture, and module expansion provided by the OSGi.NET plugin framework, the platform is modularized and divided in the system design in accordance with the functions. In the system, each module is a plugin, independently developed as a standalone project, communicating and interacting with each module through a “service” approach; when a function of the platform needs to be changed without modifying the original plugin codes, a pair of “extension points” and “extensions” based on the XML format to implement a plugin extension to another plugin. The rapid development of the platform is realized, and the problems of reusing and extensibility in practice are solved.
Using plugin development technology, a public meteorological service platform based on the OSGi.NET plugin framework is developed. According to the three functions of modularization and plugin, serviceoriented architecture, and module expansion provided by the OSGi.NET plugin framework, the platform is modularized and divided in the system design in accordance with the functions. In the system, each module is a plugin, independently developed as a standalone project, communicating and interacting with each module through a “service” approach; when a function of the platform needs to be changed without modifying the original plugin codes, a pair of “extension points” and “extensions” based on the XML format to implement a plugin extension to another plugin. The rapid development of the platform is realized, and the problems of reusing and extensibility in practice are solved.
2018, 46(2):267-274.
Abstract:
This paper presents a preliminary study that aims to find a new approach to the quick incorporating of the nonhydrostatic features of the dynamics of atmosphere into current hydrostatic Atmospheric General Circulation Models (AGCMs) in a highly efficient manner so as to enable them to accommodate the characteristics and requirements of highresolution climate modeling in the future. The study uses the WRF model as an example and compares, from both qualitative and quantitative perspectives, the hydrostatic and nonhydrostatic dynamics solvers built in the model in order to identify the factors that account for the differences between the two versions of dynamics solvers. Research shows that the differences can be represented by a “switch” variable that is capable to turn on or off the impacts of nonhydrostatic perturbations on the dynamics of the atmosphere. In addition, it is found that the variable generally has the greatest influence on the vertical motion of the atmosphere, while its impact on the atmospheric motion in the horizontal direction is rather insignificant. These observations, in fact, reveal a new possible approach to solving the problem mentioned above by focusing on constructing a highly efficient mathematical model for the switch variable and then incorporating it into the dynamics solvers adopted in current hydrostatic AGCMs.
This paper presents a preliminary study that aims to find a new approach to the quick incorporating of the nonhydrostatic features of the dynamics of atmosphere into current hydrostatic Atmospheric General Circulation Models (AGCMs) in a highly efficient manner so as to enable them to accommodate the characteristics and requirements of highresolution climate modeling in the future. The study uses the WRF model as an example and compares, from both qualitative and quantitative perspectives, the hydrostatic and nonhydrostatic dynamics solvers built in the model in order to identify the factors that account for the differences between the two versions of dynamics solvers. Research shows that the differences can be represented by a “switch” variable that is capable to turn on or off the impacts of nonhydrostatic perturbations on the dynamics of the atmosphere. In addition, it is found that the variable generally has the greatest influence on the vertical motion of the atmosphere, while its impact on the atmospheric motion in the horizontal direction is rather insignificant. These observations, in fact, reveal a new possible approach to solving the problem mentioned above by focusing on constructing a highly efficient mathematical model for the switch variable and then incorporating it into the dynamics solvers adopted in current hydrostatic AGCMs.
2018, 46(2):275-281.
Abstract:
The method of Endlich iteration and adjustment (ET method) for computing stream function and velocity potential in the limited area is used to computing the global stream function and velocity potential, which is compared with the method using the GaussSeidel iteration to solve the Poisson equations (GP method). The results show that the ET method is appropriate to compute global stream function and velocity potential, which makes the adjustment from inner to outer, i.e. using the value of the center grid to adjust that of surrounding grids. Therefore, the ET method does not need the exact boundary conditions, and eliminates the influence of the boundary on the results. The ET method can partition and reconstruct the original wind field with an accurate result. However, because of the influences of boundary conditions and difference schemes, the total of the rotational wind field and divergent wind field obtained by the GP method is different to the original wind field. In particular, when the meridional boundary has a constant value, the error between the reconstructed wind field and the original wind field is very obvious. Another important difference between the ET method and the GP method is that the former directly uses the partial differential equation between the stream function, velocity potential and wind field to make iteration and adjustment. It does not need to calculate the divergence and vorticity of the wind field, which not only guarantees the accurate reconstructed wind field, but also avoids the errors produced from the calculation of the divergence and vorticity.
The method of Endlich iteration and adjustment (ET method) for computing stream function and velocity potential in the limited area is used to computing the global stream function and velocity potential, which is compared with the method using the GaussSeidel iteration to solve the Poisson equations (GP method). The results show that the ET method is appropriate to compute global stream function and velocity potential, which makes the adjustment from inner to outer, i.e. using the value of the center grid to adjust that of surrounding grids. Therefore, the ET method does not need the exact boundary conditions, and eliminates the influence of the boundary on the results. The ET method can partition and reconstruct the original wind field with an accurate result. However, because of the influences of boundary conditions and difference schemes, the total of the rotational wind field and divergent wind field obtained by the GP method is different to the original wind field. In particular, when the meridional boundary has a constant value, the error between the reconstructed wind field and the original wind field is very obvious. Another important difference between the ET method and the GP method is that the former directly uses the partial differential equation between the stream function, velocity potential and wind field to make iteration and adjustment. It does not need to calculate the divergence and vorticity of the wind field, which not only guarantees the accurate reconstructed wind field, but also avoids the errors produced from the calculation of the divergence and vorticity.
2018, 46(2):282-291.
Abstract:
The study selected 11 cases of severe convective weather processes in the weakly forced systems in East China from March to August in 2016 According to the main influencing system and different convective types, the study contrasts GRAPESMeso simulation with WRF simulation and observation data in terms of the atmosphere circulation situation, time and space of shorttime strong rainfall, as well as moisture, heat, dynamic condition, and thunderstorm wind conditions. Results show that in the lowerlevel weak convergence weather, the south wind near the shear line simulated with GRAPESMeso is weaker than the observation; the simulated accumulative precipitation becomes stronger in the second half of simulation; the simulated extreme hourly precipitation lags behind the observation. While for the convective weather under the subtropical anticyclone, the simulated accumulative precipitation can be divided into two types: one is similar to the observation, the other is clearly weaker. For the severe convective weather occurred among the two high pressure systems, the simulated precipitation is weaker than the observation. The GRAPESMeso simulated environment is warmer and wetter before the thunderstorm winds occur, and the simulated 0-3 km and 0-6 km vertical wind shears are mostly weaker than the observation.
The study selected 11 cases of severe convective weather processes in the weakly forced systems in East China from March to August in 2016 According to the main influencing system and different convective types, the study contrasts GRAPESMeso simulation with WRF simulation and observation data in terms of the atmosphere circulation situation, time and space of shorttime strong rainfall, as well as moisture, heat, dynamic condition, and thunderstorm wind conditions. Results show that in the lowerlevel weak convergence weather, the south wind near the shear line simulated with GRAPESMeso is weaker than the observation; the simulated accumulative precipitation becomes stronger in the second half of simulation; the simulated extreme hourly precipitation lags behind the observation. While for the convective weather under the subtropical anticyclone, the simulated accumulative precipitation can be divided into two types: one is similar to the observation, the other is clearly weaker. For the severe convective weather occurred among the two high pressure systems, the simulated precipitation is weaker than the observation. The GRAPESMeso simulated environment is warmer and wetter before the thunderstorm winds occur, and the simulated 0-3 km and 0-6 km vertical wind shears are mostly weaker than the observation.
2018, 46(2):292-298.
Abstract:
Based on the observed data from the Yongxing Island weather station in Xisha Islands of the South China Sea and the NCEP/NCAR reanalysis datasets from 1960 to 2012, the characteristics of summer climate change in Xisha are analyzed, and relationships with the sealevel pressure in spring and summer in the Antarctic are discussed. The results show that there was a continuous decline of precipitation and increasing of temperature as well as remarkable weakening of wind velocity during 1960-2012 in Xisha, and meanwhile, there existed apparent interannual variability of the quasitwoyear and the decadal variability of 7 to 11 years. The results of regression analysis and correlation analysis demonstrate that the summer precipitation in Xisha was more than normal, the temperature is lower than normal, the wind velocity is more strong than normal when the sea level pressure in boreal summer and spring over the Antarctic is significantly higher than normal, resembling the negative phase of Antarctic Oscillation (AAO), and vice versa. The positive phase of AAO in spring and summer, on the one hand, resulted in the weak East summer monsoon at the interdecadal scale and led to the weak India monsoon at the interannual scale, on the other hand, inducing the decrease of precipitation and increase of temperature as well as the weakness of wind velocity in summer in Xisha.
Based on the observed data from the Yongxing Island weather station in Xisha Islands of the South China Sea and the NCEP/NCAR reanalysis datasets from 1960 to 2012, the characteristics of summer climate change in Xisha are analyzed, and relationships with the sealevel pressure in spring and summer in the Antarctic are discussed. The results show that there was a continuous decline of precipitation and increasing of temperature as well as remarkable weakening of wind velocity during 1960-2012 in Xisha, and meanwhile, there existed apparent interannual variability of the quasitwoyear and the decadal variability of 7 to 11 years. The results of regression analysis and correlation analysis demonstrate that the summer precipitation in Xisha was more than normal, the temperature is lower than normal, the wind velocity is more strong than normal when the sea level pressure in boreal summer and spring over the Antarctic is significantly higher than normal, resembling the negative phase of Antarctic Oscillation (AAO), and vice versa. The positive phase of AAO in spring and summer, on the one hand, resulted in the weak East summer monsoon at the interdecadal scale and led to the weak India monsoon at the interannual scale, on the other hand, inducing the decrease of precipitation and increase of temperature as well as the weakness of wind velocity in summer in Xisha.
14 Spatial and Temporal Variation of Extreme Precipitation Events in Eastern China from 1961 to 2014
2018, 46(2):299-306.
Abstract:
Based on the daily precipitation data of 438 stations from 1961 to 2014 in the eastern China, we calculate 4 indexes of extreme precipitation (RX1day, RX5day, CWD, SDII) defined by WMO (World Meteorological Organization), and analyze the spatial and temporal characteristics of extreme precipitation events in summer by using the areaweighted method. The results show that there were linear trends in the indexes of extreme precipitation and all indexes of extreme precipitation increased in south of the Yellow River and decreased in North China, except CWD. The indexes of extreme precipitation in summer show that RX1day, RX5day and SDII present a positive trend, and CWD shows a decreasing trend with time.
Based on the daily precipitation data of 438 stations from 1961 to 2014 in the eastern China, we calculate 4 indexes of extreme precipitation (RX1day, RX5day, CWD, SDII) defined by WMO (World Meteorological Organization), and analyze the spatial and temporal characteristics of extreme precipitation events in summer by using the areaweighted method. The results show that there were linear trends in the indexes of extreme precipitation and all indexes of extreme precipitation increased in south of the Yellow River and decreased in North China, except CWD. The indexes of extreme precipitation in summer show that RX1day, RX5day and SDII present a positive trend, and CWD shows a decreasing trend with time.
2018, 46(2):307-315.
Abstract:
The Cyclone Phase Space (CPS) as an objective method of determining Extratropical Transition (ET) has been used widely. Since the parameters of CPS may not be equal with different resolution reanalysis dataset, they bring errors in deciding the completion time of extratropical transition by using a fixed threshold. In this paper, Radom Forests (RF) method is applied to determine the completion time of TCs over the Western North Pacific from 1979 to 2016, and the factor vector consists of geographical location, center pressure, and CPS parameters. The results of the RF model show that the classification error of RF to distinguish the cyclone into a tropical cyclone or extratropical cyclone is nearly 275% on average, and the percentage of difference between determined and observed completion time within 6 hours is 718% in the training dataset, while the percentage is 659% in the testing dataset, and the percentage of difference within 12 hours exceed 80% in the later dataset. The importance analysis of variables indicates that the greatest contribution to the accuracy of determining is from latitude. The completion time determined by RF lags behind the recorded when the center pressure is lower; however, the determined time is ahead of the recorded as the center pressure is higher and temperature advection at low levels is stronger. In example application, the determined results for Mokakot (2009) and Lionrock (2016) correspond with the completion time recorded well.
The Cyclone Phase Space (CPS) as an objective method of determining Extratropical Transition (ET) has been used widely. Since the parameters of CPS may not be equal with different resolution reanalysis dataset, they bring errors in deciding the completion time of extratropical transition by using a fixed threshold. In this paper, Radom Forests (RF) method is applied to determine the completion time of TCs over the Western North Pacific from 1979 to 2016, and the factor vector consists of geographical location, center pressure, and CPS parameters. The results of the RF model show that the classification error of RF to distinguish the cyclone into a tropical cyclone or extratropical cyclone is nearly 275% on average, and the percentage of difference between determined and observed completion time within 6 hours is 718% in the training dataset, while the percentage is 659% in the testing dataset, and the percentage of difference within 12 hours exceed 80% in the later dataset. The importance analysis of variables indicates that the greatest contribution to the accuracy of determining is from latitude. The completion time determined by RF lags behind the recorded when the center pressure is lower; however, the determined time is ahead of the recorded as the center pressure is higher and temperature advection at low levels is stronger. In example application, the determined results for Mokakot (2009) and Lionrock (2016) correspond with the completion time recorded well.
2018, 46(2):316-323.
Abstract:
In accordance with the monthly global solar radiation and percentage of sunshine at 10 solar radiation observation stations in Guizhou Province during 2011-2015, the experiential coefficients in the formula are fitted in terms of the least square method. The monthly model of the parameters with the change of geographic location is established by combining with the geographic information (latitude and altitude) of the corresponding stations. Then, based on radiation data at Weining Station from 1962 to 1990, independent sample tests are carried out. At the same time, the data of Guiyang Station from 2001 to 2010 are compared with the results from the altitude partition method. The monthly total solar radiation for 85 weather stations in Guizhou Province is calculated on the basis of the determined climatic equation by the sunshine duration data and the geographic information during the period of 1981 to 2010, and the temporal and spatial distributions of total solar radiation are analyzed in detail. The results show that the calculation of solar radiation in Guizhou Province by using the monthly model of parameters had less error and higher precision, which can improve the accuracy of solar radiation calculation; the simulated solar radiations was significantly related to the observation values; the annual variation of global solar radiation took onepeak form with maximum in July and minimum in January. The annual global solar radiation in the province ranged from 341576 MJ〖DK〗·m-2 to 473704 MJ〖DK〗·m-2 from southwest to north. The minimum annual solar radiation was at Wuchuan and Maximum at Weining.
In accordance with the monthly global solar radiation and percentage of sunshine at 10 solar radiation observation stations in Guizhou Province during 2011-2015, the experiential coefficients in the formula are fitted in terms of the least square method. The monthly model of the parameters with the change of geographic location is established by combining with the geographic information (latitude and altitude) of the corresponding stations. Then, based on radiation data at Weining Station from 1962 to 1990, independent sample tests are carried out. At the same time, the data of Guiyang Station from 2001 to 2010 are compared with the results from the altitude partition method. The monthly total solar radiation for 85 weather stations in Guizhou Province is calculated on the basis of the determined climatic equation by the sunshine duration data and the geographic information during the period of 1981 to 2010, and the temporal and spatial distributions of total solar radiation are analyzed in detail. The results show that the calculation of solar radiation in Guizhou Province by using the monthly model of parameters had less error and higher precision, which can improve the accuracy of solar radiation calculation; the simulated solar radiations was significantly related to the observation values; the annual variation of global solar radiation took onepeak form with maximum in July and minimum in January. The annual global solar radiation in the province ranged from 341576 MJ〖DK〗·m-2 to 473704 MJ〖DK〗·m-2 from southwest to north. The minimum annual solar radiation was at Wuchuan and Maximum at Weining.
2018, 46(2):324-335.
Abstract:
Conventional observation, meteorological satellite, and NCEP analysis data are employed to study the interaction patterns between cold air and TC circulation and the effect of cold air on TC precipitation in two TC cases: Matmo and Soudelor. It is shown that there were obvious differences in precipitation distribution features induced by cold air in these two TCs: Matmo showing more meridional pattern; while Soudelor appearing a zonally shape. The trajectories of cold air parcels illustrated that the cold air interacted with Matmo through a northwest path including cold air from both northwest clod trough and Northeast China clod trough. Contradistinctively, the intrusion route of the cold air in Soudelor was from east, and the cold air source was only the cold trough system in Northeast China, so its intensity was much weaker. In vertical direction, the cold air intrusion at low levels was prior to that at middle levels in Matmo, and vice versa for Soudelor. These two TCs were affected by the different interaction forms of cold air. There was a distinct inverted trough at low levels with very strong cold and warmtemperature advection and distinct surface frontogenesis in Matmo, and both the positivevorticity and upward motion were located along the TC inverted trough with a northeastsouthwest distribution. As for Soudelor, with much weaker lowlevel coldadvection and surface frontogenesis, significant positive vorticity and upward motion were triggered by the lowlevel east wind jet in the north of TC circulation. Furthermore, the intensification of potential instability in the north of Soudelor caused by the middle level cold air intrusion finally resulted in the eastwest distribution of heavy rainfall along the easterly jet to the north of TC.
Conventional observation, meteorological satellite, and NCEP analysis data are employed to study the interaction patterns between cold air and TC circulation and the effect of cold air on TC precipitation in two TC cases: Matmo and Soudelor. It is shown that there were obvious differences in precipitation distribution features induced by cold air in these two TCs: Matmo showing more meridional pattern; while Soudelor appearing a zonally shape. The trajectories of cold air parcels illustrated that the cold air interacted with Matmo through a northwest path including cold air from both northwest clod trough and Northeast China clod trough. Contradistinctively, the intrusion route of the cold air in Soudelor was from east, and the cold air source was only the cold trough system in Northeast China, so its intensity was much weaker. In vertical direction, the cold air intrusion at low levels was prior to that at middle levels in Matmo, and vice versa for Soudelor. These two TCs were affected by the different interaction forms of cold air. There was a distinct inverted trough at low levels with very strong cold and warmtemperature advection and distinct surface frontogenesis in Matmo, and both the positivevorticity and upward motion were located along the TC inverted trough with a northeastsouthwest distribution. As for Soudelor, with much weaker lowlevel coldadvection and surface frontogenesis, significant positive vorticity and upward motion were triggered by the lowlevel east wind jet in the north of TC circulation. Furthermore, the intensification of potential instability in the north of Soudelor caused by the middle level cold air intrusion finally resulted in the eastwest distribution of heavy rainfall along the easterly jet to the north of TC.
2018, 46(2):336-342.
Abstract:
On 14 June 2016, a longlife supercell storm produced a wide range of hailfall and thunderstorm gale in Shandong Province. Based on the conventional observation, mesoscale automatic station, Doppler weather radar and wind profile radar data, the weather background and radar observation characteristics are analyzed, and the maintenance mechanisms are discussed. The results show that under the background of a cold vortex in North China and the environment conditions of strong deep vertical wind shear and medium convection available potential energy, the surface mesoscale convergence center triggered the strong convective storm. In the maintenance stage, there was an inflow entrance of warm and moist air on the left front of the storm at the lower level. The vertical structure showed the structural characteristics of the classical supercell, and a deep and strong mesocyclone developed, with the biggest vertical vorticity basically being above 1×10-2s-1 and each rapid increase and decrease of the central height accompanied by the occurrence of a single hail event. The supercell storm moved along the mesoscale convergence line at the development and maintenance stages, and there formed a strong convergence updraft in front of the storm because the ground cooling pool boundary expansion was balanced with the lowlevel vertical wind shear. The relative helicity of the storm was above 150 m2〖DK〗·s-2, which were the favorable conditions for the supercell storm to maintain a long time.
On 14 June 2016, a longlife supercell storm produced a wide range of hailfall and thunderstorm gale in Shandong Province. Based on the conventional observation, mesoscale automatic station, Doppler weather radar and wind profile radar data, the weather background and radar observation characteristics are analyzed, and the maintenance mechanisms are discussed. The results show that under the background of a cold vortex in North China and the environment conditions of strong deep vertical wind shear and medium convection available potential energy, the surface mesoscale convergence center triggered the strong convective storm. In the maintenance stage, there was an inflow entrance of warm and moist air on the left front of the storm at the lower level. The vertical structure showed the structural characteristics of the classical supercell, and a deep and strong mesocyclone developed, with the biggest vertical vorticity basically being above 1×10-2s-1 and each rapid increase and decrease of the central height accompanied by the occurrence of a single hail event. The supercell storm moved along the mesoscale convergence line at the development and maintenance stages, and there formed a strong convergence updraft in front of the storm because the ground cooling pool boundary expansion was balanced with the lowlevel vertical wind shear. The relative helicity of the storm was above 150 m2〖DK〗·s-2, which were the favorable conditions for the supercell storm to maintain a long time.
2018, 46(2):343-351.
Abstract:
By employing the NCEP/NCAR reanalysis data, the FY2C satellite water vapor images and the conventional meteorological data, in combination with the digitized satellite water vapor imagery and atmospheric dynamic field, the characteristics of dry intrusion and evolution and its impacts on the heavy rain during 17-18 July 2009 in Shandong Province are diagnosed. The results show that the upperlevel trough and lowlevel wind shear cyclone were helpful to the heavy rain process. There existed a strong relationship between the evolution of the dry instruction and the heavy rain process, and the dry intrusion originated from the midhigh level tilted eastward with height; heavy rainfall occurred at the forefront of the dry intrusion on the wet side of the zone where humidity gradient was at its maximum. The dark zone at the satellite water vapor image had a better correspondence with the dynamic field corresponding with the distribution of the high potential vorticity, high potential vorticity, and low humidity at 350 hPa, and the downward cold air characterized with high potential vorticity and low humidity in the upper troposphere enhanced the development of the lowlevel cyclone. The dry cold air intrusion contributed to the formation and maintenance of the dry layer, which enhanced the convective instability during the development of the heavy rain process.
By employing the NCEP/NCAR reanalysis data, the FY2C satellite water vapor images and the conventional meteorological data, in combination with the digitized satellite water vapor imagery and atmospheric dynamic field, the characteristics of dry intrusion and evolution and its impacts on the heavy rain during 17-18 July 2009 in Shandong Province are diagnosed. The results show that the upperlevel trough and lowlevel wind shear cyclone were helpful to the heavy rain process. There existed a strong relationship between the evolution of the dry instruction and the heavy rain process, and the dry intrusion originated from the midhigh level tilted eastward with height; heavy rainfall occurred at the forefront of the dry intrusion on the wet side of the zone where humidity gradient was at its maximum. The dark zone at the satellite water vapor image had a better correspondence with the dynamic field corresponding with the distribution of the high potential vorticity, high potential vorticity, and low humidity at 350 hPa, and the downward cold air characterized with high potential vorticity and low humidity in the upper troposphere enhanced the development of the lowlevel cyclone. The dry cold air intrusion contributed to the formation and maintenance of the dry layer, which enhanced the convective instability during the development of the heavy rain process.
2018, 46(2):352-360.
Abstract:
The threshold of cool summer is defined as -10 times the standard deviation of average summer air temperature anomaly, and singlestation cool summer is divided into two intensity grades: weak cool summer and strong cool summer. On the basis of the division method for singlestation cool summer, the definition method and classification standards for regional and provincial cool summer are defined, and regional and provincial cool summer intensity are identified by the percentile rank of cool summer stations respectively. The analysis of the spatial and temporal distribution characteristics of the cool summer events in Hubei Province from 1961 to 2015 shows that the cool summer event occurred more frequently in the southern and eastern Hubei than in northern and western parts. The frequency of cool summer over the southeastern Hubei was the highest while lowest in northwestern area. There occurred 7 cool summer years across Hubei over the last 55 years, including three strong years. The cool summer events occurred mainly in the 1980 s and 1990 s. Afterwards the variability of cool summer index tends to increase after the 1980s, and the provincial cool summer events still occurred in the background of global warming. By use of the NECP/NACR reanalysis dataset, the atmospheric circulation backgrounds of the cool summer years and the warm summer years and the rainy summer years are analyzed. The wave trains of mean geopotential height anomalies at 500 hPa and 100 hPa show as negative phase spatial distribution in cool summer years in the midlatitude region of the East Asia coast, and vice versa in warm summer years. The ridge line of the subtropical high was southward by 3 to 5 latitudes in cool summer years than those in warm summer years, and the ridge line of the South Asia high was southward by 2 to 3 latitudes in cool summer years than those in warm summer years. In cool summer years, there were more circulation fluctuations in at middle to high latitudes with a circulation background of two troughs and one ridge, and southward westerlies circulation. The wave trains of mean geopotential height anomaly at 500 hPa showed a “-+” distribution in cool summer years from Northeast China to South China, but the negative anomaly center was westward. Some cool summer years were also rainy summer years. There existed contemporary negative correlation and nonsignificant lag between SST Ni〖KG-*5〗n〖DD（-1*2〗〖HT〗＾〖DD)〗o 34 index of the Equatorial Middle East Pacific and the summer temperature anomaly index in Hubei Province, generally cool summer years corresponding with warm events in the Equatorial Middle East Pacific.
The threshold of cool summer is defined as -10 times the standard deviation of average summer air temperature anomaly, and singlestation cool summer is divided into two intensity grades: weak cool summer and strong cool summer. On the basis of the division method for singlestation cool summer, the definition method and classification standards for regional and provincial cool summer are defined, and regional and provincial cool summer intensity are identified by the percentile rank of cool summer stations respectively. The analysis of the spatial and temporal distribution characteristics of the cool summer events in Hubei Province from 1961 to 2015 shows that the cool summer event occurred more frequently in the southern and eastern Hubei than in northern and western parts. The frequency of cool summer over the southeastern Hubei was the highest while lowest in northwestern area. There occurred 7 cool summer years across Hubei over the last 55 years, including three strong years. The cool summer events occurred mainly in the 1980 s and 1990 s. Afterwards the variability of cool summer index tends to increase after the 1980s, and the provincial cool summer events still occurred in the background of global warming. By use of the NECP/NACR reanalysis dataset, the atmospheric circulation backgrounds of the cool summer years and the warm summer years and the rainy summer years are analyzed. The wave trains of mean geopotential height anomalies at 500 hPa and 100 hPa show as negative phase spatial distribution in cool summer years in the midlatitude region of the East Asia coast, and vice versa in warm summer years. The ridge line of the subtropical high was southward by 3 to 5 latitudes in cool summer years than those in warm summer years, and the ridge line of the South Asia high was southward by 2 to 3 latitudes in cool summer years than those in warm summer years. In cool summer years, there were more circulation fluctuations in at middle to high latitudes with a circulation background of two troughs and one ridge, and southward westerlies circulation. The wave trains of mean geopotential height anomaly at 500 hPa showed a “-+” distribution in cool summer years from Northeast China to South China, but the negative anomaly center was westward. Some cool summer years were also rainy summer years. There existed contemporary negative correlation and nonsignificant lag between SST Ni〖KG-*5〗n〖DD（-1*2〗〖HT〗＾〖DD)〗o 34 index of the Equatorial Middle East Pacific and the summer temperature anomaly index in Hubei Province, generally cool summer years corresponding with warm events in the Equatorial Middle East Pacific.
2018, 46(2):361-368.
Abstract:
In order to understand the freezing and thawing alternation process of soil and the response mechanisms to hydrothermal factors in the alpine meadows further, the soil temperature and moisture observation data of different soil layers from 1 August 2014 to 1 August 15 are used to study the dynamic characteristics of the soil temperature and moisture at different soil depths in the freezingthawing periods over alpine grasslands in the southern pastoral area of Qinghai Province. The results show that the soil freezingthawing duration of alpine grasslands in the southern pastoral area of Qinghai Province generally can be divided into 4 stages: early freezing, early frozen period, stable frozen period, and thawing period. Soil temperatures in different soil layers varied as cyclical fluctuations with the change of air temperature, and the amplitude decreased with the increase of the soil depth. In addition, the fluctuation of soil temperature and moisture in surface and subsurface layers was relatively bigger, and the sensitivity of the subsoil to hydrothermal factors was weaker. The number of completely frozen days ranges from 44 to 115, and the daily soil freezingthawing alternation process mainly occurred in the surface soil. Soil freezingthawing alternation is conducive to the soil water retention, and has a vital role in advancing the reviving dates of grassland vegetation and promoting the primary productivity.
In order to understand the freezing and thawing alternation process of soil and the response mechanisms to hydrothermal factors in the alpine meadows further, the soil temperature and moisture observation data of different soil layers from 1 August 2014 to 1 August 15 are used to study the dynamic characteristics of the soil temperature and moisture at different soil depths in the freezingthawing periods over alpine grasslands in the southern pastoral area of Qinghai Province. The results show that the soil freezingthawing duration of alpine grasslands in the southern pastoral area of Qinghai Province generally can be divided into 4 stages: early freezing, early frozen period, stable frozen period, and thawing period. Soil temperatures in different soil layers varied as cyclical fluctuations with the change of air temperature, and the amplitude decreased with the increase of the soil depth. In addition, the fluctuation of soil temperature and moisture in surface and subsurface layers was relatively bigger, and the sensitivity of the subsoil to hydrothermal factors was weaker. The number of completely frozen days ranges from 44 to 115, and the daily soil freezingthawing alternation process mainly occurred in the surface soil. Soil freezingthawing alternation is conducive to the soil water retention, and has a vital role in advancing the reviving dates of grassland vegetation and promoting the primary productivity.
2018, 46(2):369-373.
Abstract:
The late frost event on 15 May 2016 is the most serious meteorological disaster in the eastern Hexi Corridor since 2004 In this paper, by using the MICAPS real time meteorological data, physical quantity field and hourly observation data of regional stations, the causes of this freezing process are analyzed. The results show that the main causes of the disaster include the strong cold air, rapidly alternating cold air and warm air, and rapidly surface temperature rise resulted from strong warm advection, as well as the high temperature burn of crops. On the basis of the analysis of the characteristics of temperature and surface temperature, the temporal and spatial variation of regional temperature, and the evolution of the hourly temperature, this paper also analyzes the causes of the damage and further reveals the disaster characteristics from the three aspects of low temperature duration, relative humidity, high temperature burns, and the findings provide a positive and effective scientific basis for regional defense of late frosts.
The late frost event on 15 May 2016 is the most serious meteorological disaster in the eastern Hexi Corridor since 2004 In this paper, by using the MICAPS real time meteorological data, physical quantity field and hourly observation data of regional stations, the causes of this freezing process are analyzed. The results show that the main causes of the disaster include the strong cold air, rapidly alternating cold air and warm air, and rapidly surface temperature rise resulted from strong warm advection, as well as the high temperature burn of crops. On the basis of the analysis of the characteristics of temperature and surface temperature, the temporal and spatial variation of regional temperature, and the evolution of the hourly temperature, this paper also analyzes the causes of the damage and further reveals the disaster characteristics from the three aspects of low temperature duration, relative humidity, high temperature burns, and the findings provide a positive and effective scientific basis for regional defense of late frosts.
2018, 46(2):374-381.
Abstract:
Lightninggenerated NOx (LNOx) affects the distribution of atmospheric components and is the main source of Nitrogen Oxides (NOx) in the upper troposphere. Strong optical radiation produced by lightning discharge can induce photochemical reaction. Lightning discharge promotes the vertical transportation of NOx, which causes the increases of NOx content in the upper troposphere. This study is to make the quantitative analysis of the vertical column density distribution of tropospheric NOx in China and its correlation with lightning activity, by using the measurements of the lightning density observed by the LIS sensor equipped on TRMM satellite and the vertical column density of tropospheric NO2 observed by the OMI sensor equipped on Aura satellite from 2005 to 2013 respectively. It is found that the monthly variations of lightning density and tropospheric NO2 vertical column density are almost the same on the Tibet Plateau. Both of the lightning density and the tropospheric NO2vertical column density are high in summer and low in winder on the Tibet Plateau. The tropospheric NO2 vertical column density generated by each flash is about 339 mol/flash, which is evaluated by using the data from the Tibet Plateau. Based on the result of the lightninggenerated NOx, the temporal and spatial distributions of LNOx/NOx in China are evaluated. It is found that LNOx/NOx on the Tibet Plateau is about 20% to 50% in spring and summer and less than 20% in winter. The LNOx/NOx in Sichuan Basin, Yangtze River Delta and Pearl River Delta regions is high in summer and low in winter, and generally less than 20%. The average of LNOx/NOx in China is less than 10%. The lightninggenerated NOx is the main source of NOx on the Tibet Plateau, but is not the main source of NOx in Sichuan Basin, Yangtze River Delta, and Pearl River Delta regions. The results reveal the relationship between lightning activity and NOx distribution in the troposphere over China. It is also important for understanding tropospheric NOx vertical column density and its correlation with the lightning activity.
Lightninggenerated NOx (LNOx) affects the distribution of atmospheric components and is the main source of Nitrogen Oxides (NOx) in the upper troposphere. Strong optical radiation produced by lightning discharge can induce photochemical reaction. Lightning discharge promotes the vertical transportation of NOx, which causes the increases of NOx content in the upper troposphere. This study is to make the quantitative analysis of the vertical column density distribution of tropospheric NOx in China and its correlation with lightning activity, by using the measurements of the lightning density observed by the LIS sensor equipped on TRMM satellite and the vertical column density of tropospheric NO2 observed by the OMI sensor equipped on Aura satellite from 2005 to 2013 respectively. It is found that the monthly variations of lightning density and tropospheric NO2 vertical column density are almost the same on the Tibet Plateau. Both of the lightning density and the tropospheric NO2vertical column density are high in summer and low in winder on the Tibet Plateau. The tropospheric NO2 vertical column density generated by each flash is about 339 mol/flash, which is evaluated by using the data from the Tibet Plateau. Based on the result of the lightninggenerated NOx, the temporal and spatial distributions of LNOx/NOx in China are evaluated. It is found that LNOx/NOx on the Tibet Plateau is about 20% to 50% in spring and summer and less than 20% in winter. The LNOx/NOx in Sichuan Basin, Yangtze River Delta and Pearl River Delta regions is high in summer and low in winter, and generally less than 20%. The average of LNOx/NOx in China is less than 10%. The lightninggenerated NOx is the main source of NOx on the Tibet Plateau, but is not the main source of NOx in Sichuan Basin, Yangtze River Delta, and Pearl River Delta regions. The results reveal the relationship between lightning activity and NOx distribution in the troposphere over China. It is also important for understanding tropospheric NOx vertical column density and its correlation with the lightning activity.
2018, 46(2):382-389.
Abstract:
Crop simulation models are an effective and important application widely used in crop yield research and prediction, and the correction and optimization of the parameters are the premise of model simulation. The common trialerror method is lack of objectivity and of low efficiency. A sensitivity analysis of input parameters of crop models is carried out to identify the sensitivity of the parameters in simulation process, which can effectively identify the key parameters and reduce the number of parameters, so as to lay a foundation for the correction and optimization of the parameters. This paper discusses the advantages and disadvantages of both local sensitivity and global sensitivity methods of crop model analysis, such as the Fourier amplitude sensitivity test (FAST), Morris, LHOAT, Generalized Likelihood Uncertainty Estimation (GLUE), Sobol and extended Fourier amplitude sensitivity test (EFAST). The current status of research methods in crop models is reviewed and the prospects of sensitivity analysis of crop model parameters are put forward.
Crop simulation models are an effective and important application widely used in crop yield research and prediction, and the correction and optimization of the parameters are the premise of model simulation. The common trialerror method is lack of objectivity and of low efficiency. A sensitivity analysis of input parameters of crop models is carried out to identify the sensitivity of the parameters in simulation process, which can effectively identify the key parameters and reduce the number of parameters, so as to lay a foundation for the correction and optimization of the parameters. This paper discusses the advantages and disadvantages of both local sensitivity and global sensitivity methods of crop model analysis, such as the Fourier amplitude sensitivity test (FAST), Morris, LHOAT, Generalized Likelihood Uncertainty Estimation (GLUE), Sobol and extended Fourier amplitude sensitivity test (EFAST). The current status of research methods in crop models is reviewed and the prospects of sensitivity analysis of crop model parameters are put forward.
2018, 46(2):390-395.
Abstract:
In order to evaluate the suitability of tea (〖WTBX〗Camellia sinensis〖WTBZ〗) cultivation in the regions south of the Yangtze River, with the climate, topography, and soil factors taken into consideration, the article selects the annual average temperature, the annual accumulated temperature above 10 ℃, the frequency of extremely low temperature below -13 ℃, the average humidity from April to October, slope, aspect, altitude, soil pH, and soil texture to evaluate the comprehensive suitability in the regions south of the Yangtze River. The weights of suitability evaluation indexes are calculated by the AHP entropy method. Combined with the landuse map and the status of tea cultivation, the evaluation model of suitability of tea cultivation is established by the fine grid calculation. The suitability of tea cultivation is divided into 3 classes: suitable, subsuitable and nonsuitable regions. The results show that the areas of suitable, subsuitable and nonsuitable regions for tea cultivation are 3175183 km2，4103433 km2, and 1480645 km2, which accounted for 3625%, 4685% and 169% of the total evaluation area, respectively. Using the spatial distribution of tea cultivation of Songyang to validate and evaluate the comprehensive suitability regionalization of tea cultivation, it is demonstrated that the results of the model are identical with the spatial distribution of the status of tea cultivation. The evaluation results provide a scientific basis for the optimized layout of tea tree cultivation.
In order to evaluate the suitability of tea (〖WTBX〗Camellia sinensis〖WTBZ〗) cultivation in the regions south of the Yangtze River, with the climate, topography, and soil factors taken into consideration, the article selects the annual average temperature, the annual accumulated temperature above 10 ℃, the frequency of extremely low temperature below -13 ℃, the average humidity from April to October, slope, aspect, altitude, soil pH, and soil texture to evaluate the comprehensive suitability in the regions south of the Yangtze River. The weights of suitability evaluation indexes are calculated by the AHP entropy method. Combined with the landuse map and the status of tea cultivation, the evaluation model of suitability of tea cultivation is established by the fine grid calculation. The suitability of tea cultivation is divided into 3 classes: suitable, subsuitable and nonsuitable regions. The results show that the areas of suitable, subsuitable and nonsuitable regions for tea cultivation are 3175183 km2，4103433 km2, and 1480645 km2, which accounted for 3625%, 4685% and 169% of the total evaluation area, respectively. Using the spatial distribution of tea cultivation of Songyang to validate and evaluate the comprehensive suitability regionalization of tea cultivation, it is demonstrated that the results of the model are identical with the spatial distribution of the status of tea cultivation. The evaluation results provide a scientific basis for the optimized layout of tea tree cultivation.
2018, 46(2):396-402.
Abstract:
It is significant to obtain the flood inundation area accurately in time in terms of fighting against flood disasters. But it is often rainy and cloudy when flood disaster happens, so the optical remote sensing is not able to survey the flood inundation area, which will decrease the timeliness and accuracy. The Synthetic Aperture Radar (SAR) can be applied to determine the flood inundation area and flood regions of the underlying surface in time, for it is not influenced by clouds and rains and can offer allweather observation. Therefore, SAR can provide a strong guarantee for flood survey. In this article, the flood disaster in the Yangtze River region occurred in July 2016 is used as an example, in which the Sentinel1 SAR data, along with threshold and RGBband methods, are used, by means of GIS tools, to successfully extract the water areas from some lakes of the Yangtze River as well as the main stream of the Yangtze River. As a result, the submerged range and the flood area of each county are obtained. The flood area is analyzed and compared with the results of the MODIS monitoring in the same period. The results show that the method of water extraction and flood area calculation based on Sentinel1 is effective, which can be the basis of researches on the application of Sentinel1 data in flood disaster evaluation.
It is significant to obtain the flood inundation area accurately in time in terms of fighting against flood disasters. But it is often rainy and cloudy when flood disaster happens, so the optical remote sensing is not able to survey the flood inundation area, which will decrease the timeliness and accuracy. The Synthetic Aperture Radar (SAR) can be applied to determine the flood inundation area and flood regions of the underlying surface in time, for it is not influenced by clouds and rains and can offer allweather observation. Therefore, SAR can provide a strong guarantee for flood survey. In this article, the flood disaster in the Yangtze River region occurred in July 2016 is used as an example, in which the Sentinel1 SAR data, along with threshold and RGBband methods, are used, by means of GIS tools, to successfully extract the water areas from some lakes of the Yangtze River as well as the main stream of the Yangtze River. As a result, the submerged range and the flood area of each county are obtained. The flood area is analyzed and compared with the results of the MODIS monitoring in the same period. The results show that the method of water extraction and flood area calculation based on Sentinel1 is effective, which can be the basis of researches on the application of Sentinel1 data in flood disaster evaluation.
2018, 46(2):403-411.
Abstract:
In order to quantitatively evaluate the air temperature affected by roads, two types of roads were selected to do the experiments: one was the State Road with 10 meters wide, the other was the highway with 28 meters wide. The air temperature was measured at 8 points by one side of the road, the distance of the points away from the road from 15 m to 200 m. Wind speed and direction were measured at one of the points, which is 30 m from the road. The experiments were carried out from January to May, 2014, in Shanxi Province. Air temperature, wind speed and wind direction were recorded minutely. The difference of the air temperature among different points is mainly studied. The results are as follows: (1) The road was a heat source for the surrounding environment. The intensity of the heat source varied within a day, with the weather conditions, wind velocity, and the traffic of the road. Usually, it became stronger in the conditions of the sunny days, low wind speed, daytime and heavy traffic flow. But sometimes the intensity of the heat effect at night time was stronger than that in the daytime around the highway in spring. (2) The heat effect added by the traffic flow was 005 ℃ to 01 ℃ on the State Road, which with the daily traffic flow of 150 to 350, while that was 016 ℃ on the highway, which with the daily traffic flow of 2000-3500 (3) The distance by the road influenced to the air temperature was 75 m off the State Road, and 125 m off the Highway. The raising temperature effect was up to 025 to 04 ℃ on the State Road, and 02-04 ℃ on the Highway.
In order to quantitatively evaluate the air temperature affected by roads, two types of roads were selected to do the experiments: one was the State Road with 10 meters wide, the other was the highway with 28 meters wide. The air temperature was measured at 8 points by one side of the road, the distance of the points away from the road from 15 m to 200 m. Wind speed and direction were measured at one of the points, which is 30 m from the road. The experiments were carried out from January to May, 2014, in Shanxi Province. Air temperature, wind speed and wind direction were recorded minutely. The difference of the air temperature among different points is mainly studied. The results are as follows: (1) The road was a heat source for the surrounding environment. The intensity of the heat source varied within a day, with the weather conditions, wind velocity, and the traffic of the road. Usually, it became stronger in the conditions of the sunny days, low wind speed, daytime and heavy traffic flow. But sometimes the intensity of the heat effect at night time was stronger than that in the daytime around the highway in spring. (2) The heat effect added by the traffic flow was 005 ℃ to 01 ℃ on the State Road, which with the daily traffic flow of 150 to 350, while that was 016 ℃ on the highway, which with the daily traffic flow of 2000-3500 (3) The distance by the road influenced to the air temperature was 75 m off the State Road, and 125 m off the Highway. The raising temperature effect was up to 025 to 04 ℃ on the State Road, and 02-04 ℃ on the Highway.
2018, 46(2):412-417.
Abstract:
By means of the annual average thunderstorm day data, lightning location data and lightning disaster data of 10 meteorological stations in the eastern Qinghai from 1997 to 2012, the lightning location data from 2008 to 2014, and lightning disaster data from 1997 to 2014, using the number of thunderstorm days, lightning density, comprehensive disaster degree, life vulnerability modulus, and economic vulnerability modulus as vulnerability assessment indicators of lightning disasters, the vulnerability assessment model of lightning disaster is established with the weights of indexes determined by analytic hierarchy process (AHP). According to the classification method of meteorological disaster statistics, the vulnerability grades of lightning disasters are classified, and the vulnerability zoning map of lightning disasters in the eastern Qinghai is given. The results show that the vulnerability areas of lightning disasters in the eastern Qinghai exhibit a characteristic of scattered distribution; the high vulnerability areas are in Datong County, Longhua County, the second high vulnerability areas in Huzhu County in Huangzhong County, the medium vulnerability areas of vulnerability in Xining and Huangyuan County, the low vulnerability areas in Ledu District, the safe areas in Minhe County and Xunhua County.
By means of the annual average thunderstorm day data, lightning location data and lightning disaster data of 10 meteorological stations in the eastern Qinghai from 1997 to 2012, the lightning location data from 2008 to 2014, and lightning disaster data from 1997 to 2014, using the number of thunderstorm days, lightning density, comprehensive disaster degree, life vulnerability modulus, and economic vulnerability modulus as vulnerability assessment indicators of lightning disasters, the vulnerability assessment model of lightning disaster is established with the weights of indexes determined by analytic hierarchy process (AHP). According to the classification method of meteorological disaster statistics, the vulnerability grades of lightning disasters are classified, and the vulnerability zoning map of lightning disasters in the eastern Qinghai is given. The results show that the vulnerability areas of lightning disasters in the eastern Qinghai exhibit a characteristic of scattered distribution; the high vulnerability areas are in Datong County, Longhua County, the second high vulnerability areas in Huzhu County in Huangzhong County, the medium vulnerability areas of vulnerability in Xining and Huangyuan County, the low vulnerability areas in Ledu District, the safe areas in Minhe County and Xunhua County.
2018, 46(2):418-422.
Abstract:
In order to improve the forecast service of public weather index, taking 8677 cases of cardiocerebrovascular disease (CCVd) inpatients in Dandong for recent 17 years as samples, based on the analysis of the relationship between the number of CCVd inpatients and meteorological factors, the impact of sudden weather changes on the morbidity of CCVd inpatients from November to February is studied. The results show: (1) The number of cardiovascular diseases inpatients is positively correlated with the air pressure and wind speed, with the correlation coefficients being 0949 and 0933, respectively, and negatively correlated with monthly average temperature with the correlation coefficient being -0992, both passed the test of 001 significance level; the number of CCVd inpatients in winter is larger than that in summer. (2) The number of CCVd inpatients is positively correlated with meteorological conditions such as cold fronts, cyclones, coldair outbreaks and gales. The results of this study can be used as the scientific basis for public weather index forecast. When the weather conditions that are favorable to the high incidence of CCVds are predicted, the warning massages will be provided to the public in time through new media such as SMS, microblog, and WeChat, which will be beneficial to prevent and reduce the occurrence of CCVds and achieve good social benefits.
In order to improve the forecast service of public weather index, taking 8677 cases of cardiocerebrovascular disease (CCVd) inpatients in Dandong for recent 17 years as samples, based on the analysis of the relationship between the number of CCVd inpatients and meteorological factors, the impact of sudden weather changes on the morbidity of CCVd inpatients from November to February is studied. The results show: (1) The number of cardiovascular diseases inpatients is positively correlated with the air pressure and wind speed, with the correlation coefficients being 0949 and 0933, respectively, and negatively correlated with monthly average temperature with the correlation coefficient being -0992, both passed the test of 001 significance level; the number of CCVd inpatients in winter is larger than that in summer. (2) The number of CCVd inpatients is positively correlated with meteorological conditions such as cold fronts, cyclones, coldair outbreaks and gales. The results of this study can be used as the scientific basis for public weather index forecast. When the weather conditions that are favorable to the high incidence of CCVds are predicted, the warning massages will be provided to the public in time through new media such as SMS, microblog, and WeChat, which will be beneficial to prevent and reduce the occurrence of CCVds and achieve good social benefits.
2018, 46(2):423-428.
Abstract:
The TallObject Lightning Observatory in Guangzhou (TOLOG) can technically observe lightning flashes striking on tall buildings with different heights in the Pearl River New Area of Guangzhou. The waveform data of the lightning magnetic fields for 27 negative cloudtoground lightning (CG), which occurred on 14 high buildings obtained in 2011 and 2012, are collected and analyzed. The CGs include 112 returnstrokes (RSs), and 44% of them were single lightning processes. The softthreshold wavelet denoising method and the basic noise zero method are used for data preprocessing. The waveforms of the selected RS magnetic fields show multipeak patterns. Only the initial peak is valued in this paper due to the influence of the reflection peak existed among the high building group. The arithmetic mean of the number of strokes for a lightning is 42 The arithmetic mean of the number of strokes for 13 flash cases is 52, which occurred in the buildings below 200 m. The arithmetic mean of the number of strokes for 14 flash cases is 32, which occurred in the buildings above 200 m. The results show that the higher the building is, the more obvious the enhancement of the magnetic field peak value is. The geometric mean of the magnetic field peak values induced by the first and the subsequent returnstrokes occurred in the buildings above 200 m is respectively 22 times and 15 times of those induced by the first and the subsequent returnstrokes occurred in the buildings below 200 m. The building height had little effect on the wave head time. The wave head time of the magnetic field in the subsequent return stroke is far less than that of the first return stroke, which is consistent with the waveform characteristics of the return stroke.
The TallObject Lightning Observatory in Guangzhou (TOLOG) can technically observe lightning flashes striking on tall buildings with different heights in the Pearl River New Area of Guangzhou. The waveform data of the lightning magnetic fields for 27 negative cloudtoground lightning (CG), which occurred on 14 high buildings obtained in 2011 and 2012, are collected and analyzed. The CGs include 112 returnstrokes (RSs), and 44% of them were single lightning processes. The softthreshold wavelet denoising method and the basic noise zero method are used for data preprocessing. The waveforms of the selected RS magnetic fields show multipeak patterns. Only the initial peak is valued in this paper due to the influence of the reflection peak existed among the high building group. The arithmetic mean of the number of strokes for a lightning is 42 The arithmetic mean of the number of strokes for 13 flash cases is 52, which occurred in the buildings below 200 m. The arithmetic mean of the number of strokes for 14 flash cases is 32, which occurred in the buildings above 200 m. The results show that the higher the building is, the more obvious the enhancement of the magnetic field peak value is. The geometric mean of the magnetic field peak values induced by the first and the subsequent returnstrokes occurred in the buildings above 200 m is respectively 22 times and 15 times of those induced by the first and the subsequent returnstrokes occurred in the buildings below 200 m. The building height had little effect on the wave head time. The wave head time of the magnetic field in the subsequent return stroke is far less than that of the first return stroke, which is consistent with the waveform characteristics of the return stroke.
External LinksChina Meteorological AdministrationCMA Meteorological Observation CentreChinese Academy of Meteorological SciencesBeijing Meteorological ServiceNational Satellite Meteorological Center
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Supported by:Beijing E-Tiller Technology Development Co., Ltd.
Supported by:Beijing E-Tiller Technology Development Co., Ltd.