Volume 46,Issue 6,2018 Table of Contents
2018, 46(6):1065-1072.
Abstract:
For some types of newgeneration weather radar, there are problems such as instable detection, low success rate, and poor accuracy of antenna beam direction, as well as no antenna beam width and unsatisfactory measurement error detection of the full link echo intensity of the radar receiving system. Some improvements are conducted: (1) algorithm; (2) quality control method of data; (3) antenna control; (4) search mode of sun position; (5) reducing the rotating speed of antenna and increasing the acquisition resolution. The assessment shows: the detection accuracy of antenna beam direction using the improved sun method is significantly improved; the problems of instable antenna beam direction and low success rate are solved; the reliability and measurement accuracy can meet the requirements of echo intensity calibration using the sun method; and the error detection function of the whole link echo intensity measurement of the receiving system can be detected.
For some types of newgeneration weather radar, there are problems such as instable detection, low success rate, and poor accuracy of antenna beam direction, as well as no antenna beam width and unsatisfactory measurement error detection of the full link echo intensity of the radar receiving system. Some improvements are conducted: (1) algorithm; (2) quality control method of data; (3) antenna control; (4) search mode of sun position; (5) reducing the rotating speed of antenna and increasing the acquisition resolution. The assessment shows: the detection accuracy of antenna beam direction using the improved sun method is significantly improved; the problems of instable antenna beam direction and low success rate are solved; the reliability and measurement accuracy can meet the requirements of echo intensity calibration using the sun method; and the error detection function of the whole link echo intensity measurement of the receiving system can be detected.
2018, 46(6):1073-1080.
Abstract:
The radar antenna intercepts thermal radiation from various external sources. Noise varies over time and at different elevation and azimuth positions of the antenna. The traditional weather radar noise power estimation methods cannot explain the variations of noise power in azimuth. First, this paper introduces the research status of weather radar noise power estimation. Second, the RadialBased Noise power Estimation algorithm (RBNE) is described, and the steps of the RBNE algorithm are described in detail by simulation. Finally, the performance of the RBNE algorithm is tested by the measured data of the Sband weather radar. The results show that the algorithm can relatively accurately estimate the noise power at each antenna location in real time, which helps to eliminate certain types of radial interference and helps to improve the weather radar data quality.
The radar antenna intercepts thermal radiation from various external sources. Noise varies over time and at different elevation and azimuth positions of the antenna. The traditional weather radar noise power estimation methods cannot explain the variations of noise power in azimuth. First, this paper introduces the research status of weather radar noise power estimation. Second, the RadialBased Noise power Estimation algorithm (RBNE) is described, and the steps of the RBNE algorithm are described in detail by simulation. Finally, the performance of the RBNE algorithm is tested by the measured data of the Sband weather radar. The results show that the algorithm can relatively accurately estimate the noise power at each antenna location in real time, which helps to eliminate certain types of radial interference and helps to improve the weather radar data quality.
2018, 46(6):1081-1086.
Abstract:
In meteorological observation projects, the automatic observation of frozen soil has not been realized. In order to solve this problem, this paper presents a method for measuring frozen soil by means of the changes of soil dielectric constant, based on the planar capacitive sensor. When the soil is frozen, the internal moisture will turn into ice, and for the dielectric constant of water is much larger than that of ice, the dielectric constant changes drastically after water freezing (phase transformation). Based on the characteristic of soil dielectric constant and ground temperature, the mathematical model to retrieve frozen soil is established, and a typical soil laboratory freezing test is carried out. The field comparison test results show that the frozen soil sensor can correctly distinguish the soil freezing state; the measured data and manual observation are of the same trend; the correlation coefficient is up over 099; the average measurement error is less than 3 cm. The sensor based on the dielectric characteristics of the frozen soil can accurately and continuously measure the soil freezing depth and various changes.
In meteorological observation projects, the automatic observation of frozen soil has not been realized. In order to solve this problem, this paper presents a method for measuring frozen soil by means of the changes of soil dielectric constant, based on the planar capacitive sensor. When the soil is frozen, the internal moisture will turn into ice, and for the dielectric constant of water is much larger than that of ice, the dielectric constant changes drastically after water freezing (phase transformation). Based on the characteristic of soil dielectric constant and ground temperature, the mathematical model to retrieve frozen soil is established, and a typical soil laboratory freezing test is carried out. The field comparison test results show that the frozen soil sensor can correctly distinguish the soil freezing state; the measured data and manual observation are of the same trend; the correlation coefficient is up over 099; the average measurement error is less than 3 cm. The sensor based on the dielectric characteristics of the frozen soil can accurately and continuously measure the soil freezing depth and various changes.
2018, 46(6):1087-1092.
Abstract:
The large deviation in the accumulated rainfall measurements during heavy rainfall is a common problem in the application of laseroptical disdrometers, which needs to be improved. We start from the source laser and analyze its characteristics in depth and adopt a number of measures such as laser grating design, optimization algorithm, and scale calibration, so as to improve the precision of precipitation particle size measurement and the accumulated rainfall measurement accuracy. After the observation in different places in China, the results show that the design of the scale measurement accuracy of the laseroptical disdrometer has reached the goal of average absolute deviation of rainfall measurement accuracy of about 6% and the maximum deviation of less than 10% during heavy rains. Besides, the equipment has passed the test of heavy rainfall of typhoon and obtains better observation and application effects.
The large deviation in the accumulated rainfall measurements during heavy rainfall is a common problem in the application of laseroptical disdrometers, which needs to be improved. We start from the source laser and analyze its characteristics in depth and adopt a number of measures such as laser grating design, optimization algorithm, and scale calibration, so as to improve the precision of precipitation particle size measurement and the accumulated rainfall measurement accuracy. After the observation in different places in China, the results show that the design of the scale measurement accuracy of the laseroptical disdrometer has reached the goal of average absolute deviation of rainfall measurement accuracy of about 6% and the maximum deviation of less than 10% during heavy rains. Besides, the equipment has passed the test of heavy rainfall of typhoon and obtains better observation and application effects.
2018, 46(6):1093-1097.
Abstract:
The freezing rain and snow seriously affect traffic, electric power and so on all walks of life. Through the construction of a monitoring system, we add more observation elements such as snow depth, weighing precipitation， realscene observation and so on, and strengthen the automatic monitoring of snow condition and solid precipitation. Using OpenCV technology to control the quality of snow depth monitoring data, the wContour class library drawing method is used to draw the contour map in combination with the realscene photos to timely and accurately reflect the freezing rain and snow situation. By the analyzing system, integrating other meteorological observation data and using contour map, we provide intuitive and accurate weather information for meteorologists and decision departments, and further provide effective technical means for meteorological disaster prevention and mitigation, to improve the level of meteorological service.
The freezing rain and snow seriously affect traffic, electric power and so on all walks of life. Through the construction of a monitoring system, we add more observation elements such as snow depth, weighing precipitation， realscene observation and so on, and strengthen the automatic monitoring of snow condition and solid precipitation. Using OpenCV technology to control the quality of snow depth monitoring data, the wContour class library drawing method is used to draw the contour map in combination with the realscene photos to timely and accurately reflect the freezing rain and snow situation. By the analyzing system, integrating other meteorological observation data and using contour map, we provide intuitive and accurate weather information for meteorologists and decision departments, and further provide effective technical means for meteorological disaster prevention and mitigation, to improve the level of meteorological service.
2018, 46(6):1098-1102.
Abstract:
Currently, meteorological stations mostly use instruments like cameras, theodolites and laser range finders to manually calculate the assessment results of the the observed environment, according to the evaluation indicators, which for the manually measured factors, may lead to nonobjective assessment results. To deal with the problem, this study proposes a method for making a panorama and shading angle diagram for meteorological stations for improving the observation environment based on automatic panoramic image processing. This method acquires the multiple adjoining and overlapping pictures of the surrounding environment by rotary cameras and laser range finders, combines the acquired pictures into a panoramas of the observation environment with the splicing technique of a cylindrical panorama. By fusing these panoramas with a “fade in and out” effect and preprocessing these images with filtering, binarization processing, morphological processing, and edge detection, this method figures out the coordinates of the maximum boundary pixel of the panorama, the actual altitudes of the obstructions around the observation site, their distance to the observation site center and the maximum elevation of the obstructions to the center. It can also make the realtime display of the assessment. The results indicate that the method can help observation stations to improve the efficiency of environment assessment.
Currently, meteorological stations mostly use instruments like cameras, theodolites and laser range finders to manually calculate the assessment results of the the observed environment, according to the evaluation indicators, which for the manually measured factors, may lead to nonobjective assessment results. To deal with the problem, this study proposes a method for making a panorama and shading angle diagram for meteorological stations for improving the observation environment based on automatic panoramic image processing. This method acquires the multiple adjoining and overlapping pictures of the surrounding environment by rotary cameras and laser range finders, combines the acquired pictures into a panoramas of the observation environment with the splicing technique of a cylindrical panorama. By fusing these panoramas with a “fade in and out” effect and preprocessing these images with filtering, binarization processing, morphological processing, and edge detection, this method figures out the coordinates of the maximum boundary pixel of the panorama, the actual altitudes of the obstructions around the observation site, their distance to the observation site center and the maximum elevation of the obstructions to the center. It can also make the realtime display of the assessment. The results indicate that the method can help observation stations to improve the efficiency of environment assessment.
2018, 46(6):1103-1110.
Abstract:
Adopting the rain rates of 70 rain stations in Jiangsu Province as criterion，this paper compared and analyzed the applicability of precipitation products from GPM DPR in a whole year. The comparison indicates that the best time for matching of NS (Normal beam Scan), MS (Matched beam Scan) and HS (High Sensitivity beam) occurs at several minutes after overpass time. Taking NS products as an example, the annual root mean square error, correlation coefficient, and the relative bias of NS products is 2 mm/h, 05 and -20%. The precision in summer is the best, compared with other seasons. The analysis of DPR error shows that the estimated rain rate is quite sensitive to the adjusting factor 〖WTBX〗ε. 〖WTBZ〗Furthermore, the lack of algorithm limitation of 〖WTBX〗ε 〖WTBZ〗leads to the abnormality of PIA (PathIntegrated Attenuation) in the SLV module, resulting in error in precipitation retrieval.
Adopting the rain rates of 70 rain stations in Jiangsu Province as criterion，this paper compared and analyzed the applicability of precipitation products from GPM DPR in a whole year. The comparison indicates that the best time for matching of NS (Normal beam Scan), MS (Matched beam Scan) and HS (High Sensitivity beam) occurs at several minutes after overpass time. Taking NS products as an example, the annual root mean square error, correlation coefficient, and the relative bias of NS products is 2 mm/h, 05 and -20%. The precision in summer is the best, compared with other seasons. The analysis of DPR error shows that the estimated rain rate is quite sensitive to the adjusting factor 〖WTBX〗ε. 〖WTBZ〗Furthermore, the lack of algorithm limitation of 〖WTBX〗ε 〖WTBZ〗leads to the abnormality of PIA (PathIntegrated Attenuation) in the SLV module, resulting in error in precipitation retrieval.
2018, 46(6):1111-1115.
Abstract:
The 〖WTBX〗Z/I〖WTBZ〗 relationship is derived to improve the radar rainfall estimation based on the data during the period of 2015 to 2016 observed by the Parsivel raindrop spectrometer in Longyan. The relationship is applied to estimate 6 rainfall cases from 2015 to 2018 By comparing with observed data from the automatic meteorological observation stations, we can see that the accuracy of radar surface rainfall estimation increased by 50% due to the corrected Z/I relationship.
The 〖WTBX〗Z/I〖WTBZ〗 relationship is derived to improve the radar rainfall estimation based on the data during the period of 2015 to 2016 observed by the Parsivel raindrop spectrometer in Longyan. The relationship is applied to estimate 6 rainfall cases from 2015 to 2018 By comparing with observed data from the automatic meteorological observation stations, we can see that the accuracy of radar surface rainfall estimation increased by 50% due to the corrected Z/I relationship.
2018, 46(6):1116-1123.
Abstract:
The route flight temperature data are the basis of researches on route adaptability analysis, sailing analysis, and aircraft selection. Based on the NOAA historical meteorological data, this paper establishes a function model with the highest fitting degree to the original temperature data through statistics, analysis and fitting of the original temperature data, and constructs a rapid temperature estimation method for the waypoint based on the characteristics of temperature and frequency density curves. The typical latitude and longitude grid points are taken as examples. The calculation results of the direct statistical calculation and rapid estimation methods are compared with the calculation results of the Boeing WINDTEMP.EXE software. It is shown that the method for calculating the temperature of the waypoints based on statistical calculation has the advantages of accurate and reliable calculation, but the speed is slow and it is difficult to meet the operational requirements of civil aviation, but the method for rapid temperature estimation of the waypoints based on the characteristics of temperature and frequency density curves studied in this paper has the advantages of high accuracy and fast operation speed, and can meet the real needs of civil aviation operations.
The route flight temperature data are the basis of researches on route adaptability analysis, sailing analysis, and aircraft selection. Based on the NOAA historical meteorological data, this paper establishes a function model with the highest fitting degree to the original temperature data through statistics, analysis and fitting of the original temperature data, and constructs a rapid temperature estimation method for the waypoint based on the characteristics of temperature and frequency density curves. The typical latitude and longitude grid points are taken as examples. The calculation results of the direct statistical calculation and rapid estimation methods are compared with the calculation results of the Boeing WINDTEMP.EXE software. It is shown that the method for calculating the temperature of the waypoints based on statistical calculation has the advantages of accurate and reliable calculation, but the speed is slow and it is difficult to meet the operational requirements of civil aviation, but the method for rapid temperature estimation of the waypoints based on the characteristics of temperature and frequency density curves studied in this paper has the advantages of high accuracy and fast operation speed, and can meet the real needs of civil aviation operations.
2018, 46(6):1124-1129.
Abstract:
In order to meet the realtime share demand of meteorological data in Jiangsu Province after the establishment of the new data transmission process, based on message middleware technology, this study designs and realizes a provincial meteorological data synchronization system. The overall architecture and implementation of the data synchronization system are put forward; the database tables and news model are designed based on the operational needs and a data synchronization state information query web page is developed. At present, the system has been deployed in various cities across the province, providing stable, timely and effective data support for the meteorological service of provincial, municipal, and county levels.
In order to meet the realtime share demand of meteorological data in Jiangsu Province after the establishment of the new data transmission process, based on message middleware technology, this study designs and realizes a provincial meteorological data synchronization system. The overall architecture and implementation of the data synchronization system are put forward; the database tables and news model are designed based on the operational needs and a data synchronization state information query web page is developed. At present, the system has been deployed in various cities across the province, providing stable, timely and effective data support for the meteorological service of provincial, municipal, and county levels.
2018, 46(6):1130-1135.
Abstract:
In view of the fact that there is no local emergency early warning information release system in Zhejiang Province, this project implements the realtime docking of the local emergency warning information database and mainstream online media channels such as Zhejiang Weather Network, Smart Weather APP and WeChat, as well as the docking of email and fax communication means based on the TLQ message middleware and FTP message transmission mechanisms of the national emergency warning information releasing system. It is a new start for the early warning service of emergency events at present stage. It lays a foundation and provides references for the early warning service of emergency events for other provinces, where has no local early warning system.
In view of the fact that there is no local emergency early warning information release system in Zhejiang Province, this project implements the realtime docking of the local emergency warning information database and mainstream online media channels such as Zhejiang Weather Network, Smart Weather APP and WeChat, as well as the docking of email and fax communication means based on the TLQ message middleware and FTP message transmission mechanisms of the national emergency warning information releasing system. It is a new start for the early warning service of emergency events at present stage. It lays a foundation and provides references for the early warning service of emergency events for other provinces, where has no local early warning system.
2018, 46(6):1136-1146.
Abstract:
In this paper, three singlemoment microphysic schemes (Lin, WSM6, and Thompson) and three doublemoment microphysic schemes (Morrison 2mom, CAM51, and NSSL 2mom) are used to simulate 11 cases of cloud processes over Jiangsu Province based on the WRF model version 361 Using the cloud top height and temperature retrieved from satellite measurements to test the impact of different schemes on the two macro cloud parameters and select the best scheme by evaluating the performance of each scheme. Meanwhile, considering the uncertainty of individual schemes, the multischeme ensemble is used to reduce the systematic errors. Results show that all six schemes can roughly simulate the distribution of cloud bands, but there are still some differences in the range of cloud bands. The simulated cloud bands using CAM51 and NSSL 2mom scheme are larger than observations, while the others are smaller. The CAM51 forecasts of clouds are superior to those of the other schemes in terms of the anomaly correlation coefficients (ACC) and the rootmeansquare errors (RMSE). Although the NSSL scheme can reasonably simulate the location of the extreme center of cloud top height and temperature, it is still the worst scheme in terms of RMSE. The simulation performances of the Lin, WSM6 and Thompson schemes are almost the same，which perform better than that of the Morrison scheme. The multischeme ensemble mean and biasremoved ensemble mean reduce the RMSE of the cloud top height and temperature forecasts considerably. The biasremoved ensemble mean shows an improvement of forecast skill over the best single scheme forecast and the multischeme ensemble mean.
In this paper, three singlemoment microphysic schemes (Lin, WSM6, and Thompson) and three doublemoment microphysic schemes (Morrison 2mom, CAM51, and NSSL 2mom) are used to simulate 11 cases of cloud processes over Jiangsu Province based on the WRF model version 361 Using the cloud top height and temperature retrieved from satellite measurements to test the impact of different schemes on the two macro cloud parameters and select the best scheme by evaluating the performance of each scheme. Meanwhile, considering the uncertainty of individual schemes, the multischeme ensemble is used to reduce the systematic errors. Results show that all six schemes can roughly simulate the distribution of cloud bands, but there are still some differences in the range of cloud bands. The simulated cloud bands using CAM51 and NSSL 2mom scheme are larger than observations, while the others are smaller. The CAM51 forecasts of clouds are superior to those of the other schemes in terms of the anomaly correlation coefficients (ACC) and the rootmeansquare errors (RMSE). Although the NSSL scheme can reasonably simulate the location of the extreme center of cloud top height and temperature, it is still the worst scheme in terms of RMSE. The simulation performances of the Lin, WSM6 and Thompson schemes are almost the same，which perform better than that of the Morrison scheme. The multischeme ensemble mean and biasremoved ensemble mean reduce the RMSE of the cloud top height and temperature forecasts considerably. The biasremoved ensemble mean shows an improvement of forecast skill over the best single scheme forecast and the multischeme ensemble mean.
2018, 46(6):1147-1153.
Abstract:
The heavy rainfall area and maximum precipitation point were located in the southern Hainan Island during Typhoon Haiyan (1330). The causes of heavy precipitation are analyzed by using the intensive automatic weather station data, Doppler Radar data in Sanya and 025°×025° ERAinterim reanalysis data, and the WRF model is applied in the simulation experiment. The results show: (1) The easterly or southerly winds on the periphery of the typhoon were orthogonal to the southoriented Γshaped topography in the Wuzhi and Diaoluo Mountains while moving northward nearby the southern Hainan Island, and the multiple βmesoscale featured shear lines and cyclonic convergences were observed by the intensive automatic weather station and Doppler Radar in the Wuzhi Mountain and Maogan Village, where had an obvious wind direction convergence. The ground convergence center was basically consistent with the strong hourly rainfall area. (2) The local rainfall enhancement of Maogan Village was a result of interactions of the increasing of vertical velocity by the Γshaped topographical lifting, formatting of βmesoscale horizontal and vertical circulations, developing of boundarylayer convergence and upperlevel divergence. (3) The simulated strong precipitation area and extreme precipitation distributions of Haiyan were basically consistent with the observations, but the amount was less. The complex topography has positive (negative) contributions to rainfall increase (decrease) in the windward (lee) slope of mountains. It is easy to produce the βmesoscale convergence in Wuzhi Mountain and the south side of the Γshaped topography.
The heavy rainfall area and maximum precipitation point were located in the southern Hainan Island during Typhoon Haiyan (1330). The causes of heavy precipitation are analyzed by using the intensive automatic weather station data, Doppler Radar data in Sanya and 025°×025° ERAinterim reanalysis data, and the WRF model is applied in the simulation experiment. The results show: (1) The easterly or southerly winds on the periphery of the typhoon were orthogonal to the southoriented Γshaped topography in the Wuzhi and Diaoluo Mountains while moving northward nearby the southern Hainan Island, and the multiple βmesoscale featured shear lines and cyclonic convergences were observed by the intensive automatic weather station and Doppler Radar in the Wuzhi Mountain and Maogan Village, where had an obvious wind direction convergence. The ground convergence center was basically consistent with the strong hourly rainfall area. (2) The local rainfall enhancement of Maogan Village was a result of interactions of the increasing of vertical velocity by the Γshaped topographical lifting, formatting of βmesoscale horizontal and vertical circulations, developing of boundarylayer convergence and upperlevel divergence. (3) The simulated strong precipitation area and extreme precipitation distributions of Haiyan were basically consistent with the observations, but the amount was less. The complex topography has positive (negative) contributions to rainfall increase (decrease) in the windward (lee) slope of mountains. It is easy to produce the βmesoscale convergence in Wuzhi Mountain and the south side of the Γshaped topography.
2018, 46(6):1154-1164.
Abstract:
The performances of 43 CMIP5 (Coupled Model Intercomparison Project Phrase 5） models which participate in the Fifth IPCC Assessment (IPCC AR5) in simulating the land surface temperature （0 cm） over Northeast China during 1981-2005 are compared and analyzed using the outputs of CMIP5 models and the observation data from 173 meteorological stations. Results show that：most the climate model simulation results can reproduce the temporal and spatial changes of land surface temperature in the study area; the time correlation coefficient of the monthly observation is higher than 095; the cold deviation is found mostly throughout the studied period, and the simulation capability of interannual variation is limited. The spatial distribution shows that the CMIP5 models can simulate the spatial temperature distribution characteristics of high in the south and low temperature in the north over Northeast China, but the differences between the simulation results of different models are large and the models can simulate the warm and cold centers. The difference between the good and poor model groups in summer is the largest, and the poor model group cannot reproduce the distribution characteristics of the surface temperature. It is found that the FGOALS_s2 model is optimal. In general, the CMIP5 coupled climate models have good performances for the temporal and spatial variation of surface temperature in Northeast China, and the simulation performance of monthly value is better than that of interannual variation.
The performances of 43 CMIP5 (Coupled Model Intercomparison Project Phrase 5） models which participate in the Fifth IPCC Assessment (IPCC AR5) in simulating the land surface temperature （0 cm） over Northeast China during 1981-2005 are compared and analyzed using the outputs of CMIP5 models and the observation data from 173 meteorological stations. Results show that：most the climate model simulation results can reproduce the temporal and spatial changes of land surface temperature in the study area; the time correlation coefficient of the monthly observation is higher than 095; the cold deviation is found mostly throughout the studied period, and the simulation capability of interannual variation is limited. The spatial distribution shows that the CMIP5 models can simulate the spatial temperature distribution characteristics of high in the south and low temperature in the north over Northeast China, but the differences between the simulation results of different models are large and the models can simulate the warm and cold centers. The difference between the good and poor model groups in summer is the largest, and the poor model group cannot reproduce the distribution characteristics of the surface temperature. It is found that the FGOALS_s2 model is optimal. In general, the CMIP5 coupled climate models have good performances for the temporal and spatial variation of surface temperature in Northeast China, and the simulation performance of monthly value is better than that of interannual variation.
2018, 46(6):1165-1171.
Abstract:
The data from the RegCM4 model under the RCP45 scenario based on the quantitative and the qualitative assessments are selected to project the annual mean precipitation, mean, maximum and minimum temperature over Guizhou during the period of 2018 to 2050 Results show that the annual mean precipitation over Guizhou would become 85% less than that during the base period with the greatest magnitude over the north part in the first stage of the 21 century (2018 to 2028). Less rainfall would occur over the midwest and more over the eastern regions in the second stage of the 21 century (2029 to 2039) with a magnitude of 7%, while the rising tendency would be greater over northwestern regions and less over the south and east regions during the third stage of the 21 century (2040 to 2050) with a percentage increase of 75%. The annual mean, maximum and minimum temperature would increase by 06 to 13 ℃ comparing to the baseline in the first, second and third stage of the 21 century. The temperature rise would be proportional to time with less differentiation from place to place.
The data from the RegCM4 model under the RCP45 scenario based on the quantitative and the qualitative assessments are selected to project the annual mean precipitation, mean, maximum and minimum temperature over Guizhou during the period of 2018 to 2050 Results show that the annual mean precipitation over Guizhou would become 85% less than that during the base period with the greatest magnitude over the north part in the first stage of the 21 century (2018 to 2028). Less rainfall would occur over the midwest and more over the eastern regions in the second stage of the 21 century (2029 to 2039) with a magnitude of 7%, while the rising tendency would be greater over northwestern regions and less over the south and east regions during the third stage of the 21 century (2040 to 2050) with a percentage increase of 75%. The annual mean, maximum and minimum temperature would increase by 06 to 13 ℃ comparing to the baseline in the first, second and third stage of the 21 century. The temperature rise would be proportional to time with less differentiation from place to place.
2018, 46(6):1172-1179.
Abstract:
Based on the 0 5°×0 5° monthly average reanalysis data of the ERAInterim Global from 1979 to 2015, this paper calculates the relative contributions of local changes, divergence, advection and verticalterm of water vapor in the water vapor budget equation for the QinghaiTibetan Plateau, and analyzes their variation characteristics. The results show that: (1) In the whole layer and the surface layer, the divergence term of water vapor had the highest proportion in the variation term of atmospheric precipitable water; in the middle and upperlayer, the advection accounted for the highest proportion. There was a better relativity between divergence and precipitable water vapor. (2) The overall spatial distribution characteristic of water vapor divergence was lowlayer convergence and upperlayer divergence; in the whole layer and surface layer, there was moist advection in the eastern part of the plateau, and there was dry advection the rest of the region. In the middle layer, the moist advection region was large, and there was dry advection almost in the upper layer. (3) The interannual variation of water vapor divergence showed an increasing trend, in which the increasing trend was the most obvious in the whole layer, surface layer and the middle layer; and the interannual variation of the water vapor advection showed a downward trend in the whole layer and the other three layers, most obvious in the middle and upperlayer.
Based on the 0 5°×0 5° monthly average reanalysis data of the ERAInterim Global from 1979 to 2015, this paper calculates the relative contributions of local changes, divergence, advection and verticalterm of water vapor in the water vapor budget equation for the QinghaiTibetan Plateau, and analyzes their variation characteristics. The results show that: (1) In the whole layer and the surface layer, the divergence term of water vapor had the highest proportion in the variation term of atmospheric precipitable water; in the middle and upperlayer, the advection accounted for the highest proportion. There was a better relativity between divergence and precipitable water vapor. (2) The overall spatial distribution characteristic of water vapor divergence was lowlayer convergence and upperlayer divergence; in the whole layer and surface layer, there was moist advection in the eastern part of the plateau, and there was dry advection the rest of the region. In the middle layer, the moist advection region was large, and there was dry advection almost in the upper layer. (3) The interannual variation of water vapor divergence showed an increasing trend, in which the increasing trend was the most obvious in the whole layer, surface layer and the middle layer; and the interannual variation of the water vapor advection showed a downward trend in the whole layer and the other three layers, most obvious in the middle and upperlayer.
2018, 46(6):1180-1187.
Abstract:
In order to study the variation characteristics and the causes of pan evaporation of the BeijingTianjinHebei region, the 87 weather stations with more complete and longer time data sequence and over 70 score of station observation environment are selected from more than 200 stations in the BeijingTianjinHebei region (according to the standard score of the China Meteorological Administration). The evaporation pan evaporation data and other meteorological observation data in the 87 weather stations are used to analyze the evaporation variation characteristics and impact factors in the BeijingTianjinHebei region from 1970 to 2013 with the linear trend estimation method and complete correlation coefficient method. The results indicate that, the annual and seasonal evaporation showed an obvious decreasing trend in recent 44 years in the BeijingTianjinHebei region. The sequence of vaporization rates from big to small is: Piedmont plain > Taihang mountain > Hebei east plain > Yanshan hills > Hebei north plateau. The evaporation rate was gradually increasing from north to south. The drop rate of pan evaporation was: spring > autumn > winter > summer. Evaporation capacity and influence factors are analyzed. The results show that temperature daily range, sunshine duration and average wind speed are the major causes of the evaporation reduction in the BeijingTianjinHebei region. In the plain area, average wind speed is the dominant factor. In the mountainous and plateau areas, sunshine duration is the dominant factor.
In order to study the variation characteristics and the causes of pan evaporation of the BeijingTianjinHebei region, the 87 weather stations with more complete and longer time data sequence and over 70 score of station observation environment are selected from more than 200 stations in the BeijingTianjinHebei region (according to the standard score of the China Meteorological Administration). The evaporation pan evaporation data and other meteorological observation data in the 87 weather stations are used to analyze the evaporation variation characteristics and impact factors in the BeijingTianjinHebei region from 1970 to 2013 with the linear trend estimation method and complete correlation coefficient method. The results indicate that, the annual and seasonal evaporation showed an obvious decreasing trend in recent 44 years in the BeijingTianjinHebei region. The sequence of vaporization rates from big to small is: Piedmont plain > Taihang mountain > Hebei east plain > Yanshan hills > Hebei north plateau. The evaporation rate was gradually increasing from north to south. The drop rate of pan evaporation was: spring > autumn > winter > summer. Evaporation capacity and influence factors are analyzed. The results show that temperature daily range, sunshine duration and average wind speed are the major causes of the evaporation reduction in the BeijingTianjinHebei region. In the plain area, average wind speed is the dominant factor. In the mountainous and plateau areas, sunshine duration is the dominant factor.
2018, 46(6):1188-1200.
Abstract:
By using the routine observation, automatic station and radar echo data, the environmental conditions and echo characteristics of two strong convective weather events in Shandong in June 2016 are analyzed. The results show: The storm on 14 June occurred under the circulation of cold air guided by a transversal trough and that on 30 June appeared under the circulation of the southwest air before the upperlevel trough. The ground mesoscale convergence zones were the trigger mechanism. The average wind speed of the vertical wind shear and storm bearing layer on 14 June was greater than that of 30 June, leading to the obvious strengthening of the storm and the longer duration of the supercell. The magnitude of SRH (Storm Relative Helicity) had a good indication for the strengthening of strong convective weather. Both processes formed near the ground convergence line and had mesocyclones, hanging strong echoes, BWER (Bounded Weak Echo Region), echo pendency, and storm top divergence. The differences were that there was an inverted Vshaped gap, middlelevel radial convergence, TBSS (ThreeBody Scattering Spike) and hook echoes on 14 June; narrow band echoes and the larger area of radial velocity on 30 June. Small hails occurred in two processes caused by weak rotation, which is worth noting in forecasting. Two hail processes are related with the maximum reflectivity, cell top, VIL, and density of the storm, as well as the thickness, maximum shear, and duration of the mesocyclone.
By using the routine observation, automatic station and radar echo data, the environmental conditions and echo characteristics of two strong convective weather events in Shandong in June 2016 are analyzed. The results show: The storm on 14 June occurred under the circulation of cold air guided by a transversal trough and that on 30 June appeared under the circulation of the southwest air before the upperlevel trough. The ground mesoscale convergence zones were the trigger mechanism. The average wind speed of the vertical wind shear and storm bearing layer on 14 June was greater than that of 30 June, leading to the obvious strengthening of the storm and the longer duration of the supercell. The magnitude of SRH (Storm Relative Helicity) had a good indication for the strengthening of strong convective weather. Both processes formed near the ground convergence line and had mesocyclones, hanging strong echoes, BWER (Bounded Weak Echo Region), echo pendency, and storm top divergence. The differences were that there was an inverted Vshaped gap, middlelevel radial convergence, TBSS (ThreeBody Scattering Spike) and hook echoes on 14 June; narrow band echoes and the larger area of radial velocity on 30 June. Small hails occurred in two processes caused by weak rotation, which is worth noting in forecasting. Two hail processes are related with the maximum reflectivity, cell top, VIL, and density of the storm, as well as the thickness, maximum shear, and duration of the mesocyclone.
2018, 46(6):1201-1210.
Abstract:
Using the conventional observation data，precipitation data of automatic weather stations and NCEP 1°×1° reanalysis data, we comparatively diagnose two heavy rainfall processes happened in the middle South Xinjiang on 14 April 2017 (4〖DK〗·14) and 1 to 2 May 2017 (5〖DK〗·1), the similarities and differences in meteorological dynamics of two spring heavy rains are discussed. The results indicate that the spring heavy rains occurred in a background of the active subtropical westerly jet, the northward extended Iranian subtropical high, the active ground cold front, and lower and upperlevel jetfront systems. The water vapor was from the Arabian and Caspian sea of around 40°E， which came into Xinjiang followed by west winds， and then converges at the middle South Xinjiang with the favorable wind condition. The upperlevel and lowlevel jets were coupled to form the secondary vertical circulation, and dry and cold air invasion prompted the atmosphere instability and precipitation intensity. The main differences between two processes are: the subtropical westerly jet was abnormally shifting northwards at 500 hPa, resulting in the shortwave trough and the cold air from western at surface in the April rainfall. While the polar front jet and the subtropical westerly jet were joined together at 500 hPa, there existed a long wave trough and cold air from northwest at the surface in the May rainfall. The April rainfall is a typical jet stream front type rain with convection precipitation, during which there were two secondary vertical circulations formed, with the lower one caused by three cold air flows from different directions, triggering the nearby cyclonic circulation at 850 hPa.The May rainfall is a typical jet stream with cold front， in which the downward incursion of upperlevel cold air triggered a powerful integrated secondary vertical circulation and enhanced the precipitation.
Using the conventional observation data，precipitation data of automatic weather stations and NCEP 1°×1° reanalysis data, we comparatively diagnose two heavy rainfall processes happened in the middle South Xinjiang on 14 April 2017 (4〖DK〗·14) and 1 to 2 May 2017 (5〖DK〗·1), the similarities and differences in meteorological dynamics of two spring heavy rains are discussed. The results indicate that the spring heavy rains occurred in a background of the active subtropical westerly jet, the northward extended Iranian subtropical high, the active ground cold front, and lower and upperlevel jetfront systems. The water vapor was from the Arabian and Caspian sea of around 40°E， which came into Xinjiang followed by west winds， and then converges at the middle South Xinjiang with the favorable wind condition. The upperlevel and lowlevel jets were coupled to form the secondary vertical circulation, and dry and cold air invasion prompted the atmosphere instability and precipitation intensity. The main differences between two processes are: the subtropical westerly jet was abnormally shifting northwards at 500 hPa, resulting in the shortwave trough and the cold air from western at surface in the April rainfall. While the polar front jet and the subtropical westerly jet were joined together at 500 hPa, there existed a long wave trough and cold air from northwest at the surface in the May rainfall. The April rainfall is a typical jet stream front type rain with convection precipitation, during which there were two secondary vertical circulations formed, with the lower one caused by three cold air flows from different directions, triggering the nearby cyclonic circulation at 850 hPa.The May rainfall is a typical jet stream with cold front， in which the downward incursion of upperlevel cold air triggered a powerful integrated secondary vertical circulation and enhanced the precipitation.
2018, 46(6):1211-1220.
Abstract:
Based on the conventional observation data, regional intensive automatic weather station data, GPSPWV data and NCEP 1°×1° reanalysis data, the shorttime heavy rainfall in Nanchang on 21August 2012 is analyzed. The discussion is focused on the causes of the local heavy rainstorm. The results show: The confrontation of a midlatitude trough, the Northeast Subtropical High, and a southeastern tropical system resulted in the accumulation of high energy unstable atmosphere and strong convective movement near Nanchang, and then led to the local rainstorm. The topographic uplift was a direct inducement of the rainstorm. Due to the uplifting effect of the Meiling Mountains, the unstable atmosphere ascended above its free convection height and developed into mesoscale cyclones near the Meiling Mountains. The cyclone moved along the mesoscale convergence line to the vicinity of Nanchang, and maintained for three hours. The rainstorm was composed of a number of strong or extrastrong meso and microscale rainfall centers. The ground mesoscale cyclone, high CAPE values, high and strong water vapor convergence made the MCSs maintained for a long time, which led to mesoscale rainfall centers repeatedly generated and developed around Nanchang. Summarizing the rainstorm flow pattern, we can construct the predictive conceptual model under the condition of weak southwest airflow and provide technical guidance for forecasters to capture such local heavy rainstorms.
Based on the conventional observation data, regional intensive automatic weather station data, GPSPWV data and NCEP 1°×1° reanalysis data, the shorttime heavy rainfall in Nanchang on 21August 2012 is analyzed. The discussion is focused on the causes of the local heavy rainstorm. The results show: The confrontation of a midlatitude trough, the Northeast Subtropical High, and a southeastern tropical system resulted in the accumulation of high energy unstable atmosphere and strong convective movement near Nanchang, and then led to the local rainstorm. The topographic uplift was a direct inducement of the rainstorm. Due to the uplifting effect of the Meiling Mountains, the unstable atmosphere ascended above its free convection height and developed into mesoscale cyclones near the Meiling Mountains. The cyclone moved along the mesoscale convergence line to the vicinity of Nanchang, and maintained for three hours. The rainstorm was composed of a number of strong or extrastrong meso and microscale rainfall centers. The ground mesoscale cyclone, high CAPE values, high and strong water vapor convergence made the MCSs maintained for a long time, which led to mesoscale rainfall centers repeatedly generated and developed around Nanchang. Summarizing the rainstorm flow pattern, we can construct the predictive conceptual model under the condition of weak southwest airflow and provide technical guidance for forecasters to capture such local heavy rainstorms.
2018, 46(6):1221-1231.
Abstract:
By utilizing the conventional meteorological data, precipitation data of automatic meteorological stations, and NCEP reanalysis data (1°×1°), the process of the severe rainstorm happened in Fujian in early June 2017 is analyzed. Some conclusions are derived from the results: (1) The continuous precipitation was formed by the interaction of the northern cold air flow and the warm and wet flow from the south. The activity of mesoscale systems caused the shortterm rainstorm. (2) Relatively large relative helicity, positive vorticity at the lower level, and rising movement at the middle and low levels were beneficial to the development and maintenance of MCSs. Strong thermal instability and strong vertical wind shear were the ambient characteristics of mesoscale convective development. (3) The strong whole layer vapor flux and water vapor convergence provided water vapor sources and conditions for the rainstorm area. (4)The size and position of the frontogenesis can be exploited as good indicators of the intensity and the falling area of the rainstorm. The lower level was dominated by horizontal frontogenesis and the middlelevel was dominated by vertical frontogenesis, which was beneficial to large areas of heavy rainfall. (5) The mesoscale systems played a role in strengthening synoptic scale water vapor convergence, and meanwhile enhanced the convective instability conditions of the boundary layer. The upper and lower branches of the two secondary circulations were superposed, and this superposition was beneficial to the release of the instability energy accumulated at lower level, and promoted the development of the mesoscale system.
By utilizing the conventional meteorological data, precipitation data of automatic meteorological stations, and NCEP reanalysis data (1°×1°), the process of the severe rainstorm happened in Fujian in early June 2017 is analyzed. Some conclusions are derived from the results: (1) The continuous precipitation was formed by the interaction of the northern cold air flow and the warm and wet flow from the south. The activity of mesoscale systems caused the shortterm rainstorm. (2) Relatively large relative helicity, positive vorticity at the lower level, and rising movement at the middle and low levels were beneficial to the development and maintenance of MCSs. Strong thermal instability and strong vertical wind shear were the ambient characteristics of mesoscale convective development. (3) The strong whole layer vapor flux and water vapor convergence provided water vapor sources and conditions for the rainstorm area. (4)The size and position of the frontogenesis can be exploited as good indicators of the intensity and the falling area of the rainstorm. The lower level was dominated by horizontal frontogenesis and the middlelevel was dominated by vertical frontogenesis, which was beneficial to large areas of heavy rainfall. (5) The mesoscale systems played a role in strengthening synoptic scale water vapor convergence, and meanwhile enhanced the convective instability conditions of the boundary layer. The upper and lower branches of the two secondary circulations were superposed, and this superposition was beneficial to the release of the instability energy accumulated at lower level, and promoted the development of the mesoscale system.
2018, 46(6):1232-1239.
Abstract:
Based on the normal observation data from 10 to 12 December 2014, ECWMF reanalysis data and Kaband millimeterwave cloud radar data, using the methods of physical diagnosis and echo characteristics analysis, the more refined vertical micro features, compared with weather radar, are obtained. The new formation and evolution observations of freezing rains in Guizhou are provided. The result shows: (1) The ground temperature in the freezing rain process was near 0 ℃. After clouds had formed, its temperature decreased with height and always maintained between -10 and 0 ℃. It is a supercooled warm rain process. (2) The echo intensity of the freezing rain increased gradually with decreasing height in the primary, maturation and extinction stages, ranging from -30 to 12 dBz. The vertical velocity of the air is concentrated in the range of -04 to 16 m/s, and the velocity of the particles falls within 24 m/s. (3) The ascending motion was weak and the particle size was small in the primary and extinction stages of the freezing rain. In the mature stage, the updraft increased, then the proportion of small particles decreased, and the number of large particles increased. In the middle and lower parts of the cloud, the large value region of the spectrum corresponded to the strong reflectivity factor, which reflects the collision growth in the falling process of supercooled liquid water.
Based on the normal observation data from 10 to 12 December 2014, ECWMF reanalysis data and Kaband millimeterwave cloud radar data, using the methods of physical diagnosis and echo characteristics analysis, the more refined vertical micro features, compared with weather radar, are obtained. The new formation and evolution observations of freezing rains in Guizhou are provided. The result shows: (1) The ground temperature in the freezing rain process was near 0 ℃. After clouds had formed, its temperature decreased with height and always maintained between -10 and 0 ℃. It is a supercooled warm rain process. (2) The echo intensity of the freezing rain increased gradually with decreasing height in the primary, maturation and extinction stages, ranging from -30 to 12 dBz. The vertical velocity of the air is concentrated in the range of -04 to 16 m/s, and the velocity of the particles falls within 24 m/s. (3) The ascending motion was weak and the particle size was small in the primary and extinction stages of the freezing rain. In the mature stage, the updraft increased, then the proportion of small particles decreased, and the number of large particles increased. In the middle and lower parts of the cloud, the large value region of the spectrum corresponded to the strong reflectivity factor, which reflects the collision growth in the falling process of supercooled liquid water.
2018, 46(6):1240-1250.
Abstract:
Using the data from surface observation, radiosondes, AWSs, Doppler radar and NCEP reanalysis, the mechanism of the wind shear event is analyzed. The results are as followings: (1) The main reason of the lowlevel wind shear at Hefei Airport was the turbulence at the bottom of the mesoγ scale convective cell, which was caused by the convergence of the northern gust front and the mesoscale convergence line. The downdraft produced by the rapid extinction of multiple mesoscale convective cells strengthened the surface mesoscale convergence line. The gust front and mesoscale convergence line caused the lowlevel wind shear at the airport. (2) The atmospheric stratification was unstable in the northern Anhui before the wind shear occurred. The wind field convergence at 925 hPa provided a triggering mechanism for the strong convective weather, and the easterly flow passing through the Yellow Sea brought enough water vapor to the lower layer. The development and elimination of the severe convective storm in northern Anhui was the fundamental reason for the occurrence of the northern gust front. (3) The midlevel dry and cold air behind the storm hindered the warm air rising, promoted the sinking of the cold air inside the storm and the vertical momentum exchange, which made the outflow intensity of the ground layer enhanced. The two rapid drops of the core height of strong reflectivity factor were the direct cause of the occurrence of the northern gust front.
Using the data from surface observation, radiosondes, AWSs, Doppler radar and NCEP reanalysis, the mechanism of the wind shear event is analyzed. The results are as followings: (1) The main reason of the lowlevel wind shear at Hefei Airport was the turbulence at the bottom of the mesoγ scale convective cell, which was caused by the convergence of the northern gust front and the mesoscale convergence line. The downdraft produced by the rapid extinction of multiple mesoscale convective cells strengthened the surface mesoscale convergence line. The gust front and mesoscale convergence line caused the lowlevel wind shear at the airport. (2) The atmospheric stratification was unstable in the northern Anhui before the wind shear occurred. The wind field convergence at 925 hPa provided a triggering mechanism for the strong convective weather, and the easterly flow passing through the Yellow Sea brought enough water vapor to the lower layer. The development and elimination of the severe convective storm in northern Anhui was the fundamental reason for the occurrence of the northern gust front. (3) The midlevel dry and cold air behind the storm hindered the warm air rising, promoted the sinking of the cold air inside the storm and the vertical momentum exchange, which made the outflow intensity of the ground layer enhanced. The two rapid drops of the core height of strong reflectivity factor were the direct cause of the occurrence of the northern gust front.
2018, 46(6):1251-1257.
Abstract:
The weather condition, atmospheric circulation background, formation mechanism and pollutant trajectory of a heavy air pollution event occurring from 18 to 21 December of 2016 in Qingdao are analyzed based on the data of air quality observation，the routine weather observation and NCEP reanalysis data. The results are as follows: During heavy air pollution process, the 500 hPa circulation was the meridional pattern including two troughs and a ridge at high latitudes, with Qingdao under the control of a weak trough system. When air quality improved, the front and winds at 500 hPa enhanced, and the ground cold front moved to the east. The relative humidity near the ground maintained high constantly during the heavy pollution of haze, and the surface wind speed of less than 26 m〖DK〗·s-1 had no obvious effect on the pollutant diffusion during the heavy pollution. The increasing concentration of pollutants and pollution duration were negatively correlated with such meteorological factor as visibility, wind speed, mixing layer and thickness, and positively correlated with the relative humidity; and the correlation with temperature was low. The 24h inputted pollutant sources in Qingdao were mainly from the northern part of the peninsula, with the main pollutants being PM25.
The weather condition, atmospheric circulation background, formation mechanism and pollutant trajectory of a heavy air pollution event occurring from 18 to 21 December of 2016 in Qingdao are analyzed based on the data of air quality observation，the routine weather observation and NCEP reanalysis data. The results are as follows: During heavy air pollution process, the 500 hPa circulation was the meridional pattern including two troughs and a ridge at high latitudes, with Qingdao under the control of a weak trough system. When air quality improved, the front and winds at 500 hPa enhanced, and the ground cold front moved to the east. The relative humidity near the ground maintained high constantly during the heavy pollution of haze, and the surface wind speed of less than 26 m〖DK〗·s-1 had no obvious effect on the pollutant diffusion during the heavy pollution. The increasing concentration of pollutants and pollution duration were negatively correlated with such meteorological factor as visibility, wind speed, mixing layer and thickness, and positively correlated with the relative humidity; and the correlation with temperature was low. The 24h inputted pollutant sources in Qingdao were mainly from the northern part of the peninsula, with the main pollutants being PM25.
2018, 46(6):1258-1265.
Abstract:
Particle size distributions and complex refractive index are basic physical parameters to describe the atmospheric aerosol and also the basic parameters of remote sensing the atmospheric aerosol optical depth, which determines the accuracy of optical depth remote sensing. This paper studies the volume size distribution and the complex refractive index of atmospheric aerosols around Beijing inverted by the China Aerosol Remote Sensing Network in dust and haze days. The results reveal that the volume size distributions of atmospheric aerosol in both dust and haze days show a bimodal logarithmic normal distribution. The volume size distribution of the atmospheric aerosol particles in haze days takes up an approximately same proportions in the fine mode (01 to 1 microns) and coarse mode (1 to 10 microns). However, the coarse mode in the volume size distribution of atmospheric aerosol particles in dust days take up a much larger proportion than the fine mode with the coarse particles being dominant. By comparing the actually measured complex refractive index with all types of aerosol complex refractive index spectroscopic data in the HITRAN 2008 Database, we can find that within the actually measured 07 to 10 μm spectral range, the real and imaginary parts of sandlike particles are close to dust aerosols and water soluble particles are close to haze aerosols. If lacking complex refractive indexes in remote sensing, we can use those of sandlike particles and water soluble particles (02 to 40 microns) to approximately replace the dust and haze aerosols for ultraviolet and infrared remote sensing. The study provides a reference for dust and haze aerosol researches by using the quantifying ultraviolet and infrared remote sensing.
Particle size distributions and complex refractive index are basic physical parameters to describe the atmospheric aerosol and also the basic parameters of remote sensing the atmospheric aerosol optical depth, which determines the accuracy of optical depth remote sensing. This paper studies the volume size distribution and the complex refractive index of atmospheric aerosols around Beijing inverted by the China Aerosol Remote Sensing Network in dust and haze days. The results reveal that the volume size distributions of atmospheric aerosol in both dust and haze days show a bimodal logarithmic normal distribution. The volume size distribution of the atmospheric aerosol particles in haze days takes up an approximately same proportions in the fine mode (01 to 1 microns) and coarse mode (1 to 10 microns). However, the coarse mode in the volume size distribution of atmospheric aerosol particles in dust days take up a much larger proportion than the fine mode with the coarse particles being dominant. By comparing the actually measured complex refractive index with all types of aerosol complex refractive index spectroscopic data in the HITRAN 2008 Database, we can find that within the actually measured 07 to 10 μm spectral range, the real and imaginary parts of sandlike particles are close to dust aerosols and water soluble particles are close to haze aerosols. If lacking complex refractive indexes in remote sensing, we can use those of sandlike particles and water soluble particles (02 to 40 microns) to approximately replace the dust and haze aerosols for ultraviolet and infrared remote sensing. The study provides a reference for dust and haze aerosol researches by using the quantifying ultraviolet and infrared remote sensing.
2018, 46(6):1266-1273.
Abstract:
With the daytoday radiosonde temperature inversion data of 2013 to 2016 in Harbin at 07:00 and 19:00 and the monitoring data of air pollutants of the Harbin environmental monitoring station, the characteristics of the lowtemperature stratification in Harbin and the relationship with the concentrations of four main air pollutants (SO2,NO2,PM10 and PM25) are statistically analyzed The results indicate that the frequency of continuous temperature inversion of the weather was 615% and 588% at 07:00 and 19:00, respectively, in the period of 2013 to 2016 The trends of monthly variation of temperature inversion are basically the same, and the seasonal variation trends are consistent: winter > autumn > spring > summer. The occurrence frequency of the temperature inversion in winter in Harbin is significantly higher than that in summer, autumn and winter. The concentration of air pollutants in Harbin was, in the recent 4 years, positively correlated with the with the frequency and the thickness of the continuous inversion, and positively correlated with the inversion intensity at 07:00, and the correlation with the intensity at 19:00 was not obvious, indicating that the lowlevel atmospheric inversion in Harbin is one of the main factors affecting the air quality of Harbin. The weak cold advection at high latitudes, the warm lower layer, the weak air pressure field at the sea level, and the poor horizontal and the vertical transportation made the pollutants difficult to spread and accumulate, which is the important cause of the severe pollution in the last few days.
With the daytoday radiosonde temperature inversion data of 2013 to 2016 in Harbin at 07:00 and 19:00 and the monitoring data of air pollutants of the Harbin environmental monitoring station, the characteristics of the lowtemperature stratification in Harbin and the relationship with the concentrations of four main air pollutants (SO2,NO2,PM10 and PM25) are statistically analyzed The results indicate that the frequency of continuous temperature inversion of the weather was 615% and 588% at 07:00 and 19:00, respectively, in the period of 2013 to 2016 The trends of monthly variation of temperature inversion are basically the same, and the seasonal variation trends are consistent: winter > autumn > spring > summer. The occurrence frequency of the temperature inversion in winter in Harbin is significantly higher than that in summer, autumn and winter. The concentration of air pollutants in Harbin was, in the recent 4 years, positively correlated with the with the frequency and the thickness of the continuous inversion, and positively correlated with the inversion intensity at 07:00, and the correlation with the intensity at 19:00 was not obvious, indicating that the lowlevel atmospheric inversion in Harbin is one of the main factors affecting the air quality of Harbin. The weak cold advection at high latitudes, the warm lower layer, the weak air pressure field at the sea level, and the poor horizontal and the vertical transportation made the pollutants difficult to spread and accumulate, which is the important cause of the severe pollution in the last few days.
2018, 46(6):1274-1279.
Abstract:
In this paper, the monitoring results and trends of six air pollutants including SO2, NO2, PM10, PM25, CO, O3 in Lhasa from 2014 to 2016 are analyzed and evaluated.In addition, the main factors affecting the quality of Lhasa’s atmospheric environment are also discussed. The results are as follows: (1) the main pollutants in the urban area of Lhasa were mainly PM10, followed by O3; (2) the content of SO2 and CO in the atmospheric environment decreased year by year during the observation period; however, the content of NO2 in the atmospheric environment over Lhasa showed a trend of increasing year by year during these three years; (3) the ratio of PM25/PM10 in the atmospheric environment of Lhasa was obviously low, indicating that the main influencing factors of atmospheric environmental quality in Lhasa are natural factors.
In this paper, the monitoring results and trends of six air pollutants including SO2, NO2, PM10, PM25, CO, O3 in Lhasa from 2014 to 2016 are analyzed and evaluated.In addition, the main factors affecting the quality of Lhasa’s atmospheric environment are also discussed. The results are as follows: (1) the main pollutants in the urban area of Lhasa were mainly PM10, followed by O3; (2) the content of SO2 and CO in the atmospheric environment decreased year by year during the observation period; however, the content of NO2 in the atmospheric environment over Lhasa showed a trend of increasing year by year during these three years; (3) the ratio of PM25/PM10 in the atmospheric environment of Lhasa was obviously low, indicating that the main influencing factors of atmospheric environmental quality in Lhasa are natural factors.
2018, 46(6):1280-1286.
Abstract:
Based on the data of the Digital Elevation Model (DEM) of Sichuan and hail observation of 45 years (1970-2014) from 143 weather stations in Sichuan Province, using such methods as correlation analysis, stepwise regression, digital terrain analysis and zonal statistics, the research is carried out on the relationship between hail distribution and elevation, slope, aspect, longitude, latitude, relief, and terrain cutting depth over Sichuan Province. The results show that the characteristic of hail distribution in Sichuan Province is obviously geographical—the main influencing factors of hail distribution are elevation, longitude, relief, and slope direction (northwest to west). The regression equation simulating the spatial distribution of hail is also established, and the conclusion shows the consistency of simulated values with actual data, though the simulated values are overall smaller.
Based on the data of the Digital Elevation Model (DEM) of Sichuan and hail observation of 45 years (1970-2014) from 143 weather stations in Sichuan Province, using such methods as correlation analysis, stepwise regression, digital terrain analysis and zonal statistics, the research is carried out on the relationship between hail distribution and elevation, slope, aspect, longitude, latitude, relief, and terrain cutting depth over Sichuan Province. The results show that the characteristic of hail distribution in Sichuan Province is obviously geographical—the main influencing factors of hail distribution are elevation, longitude, relief, and slope direction (northwest to west). The regression equation simulating the spatial distribution of hail is also established, and the conclusion shows the consistency of simulated values with actual data, though the simulated values are overall smaller.
2018, 46(6):1287-1290.
Abstract:
Based on the daily and hourly surface meteorological observation data of Huangshan Station from 2004 to 2016, the temporal distribution and climatic conditions of rime are analyzed. The results show that: (1) The annual average number of rime days in Huangshan is 616, with obvious differences between years. The earliest day of rime was mainly in November and the latest day was mainly in March and April. The number of consecutive rime days is often 3 to 4 days, accounting for 40% of the total number. In each year there were continuous rime days of ≥ 10 days. (2) The rime appeared mainly from October to next April, of which the number of rime days from December to next March accounted for 898%. The monthly mean number of rime days is significantly negatively correlated with the monthly mean temperature. There was a certain daily change in rime, with the highest number at 09:00, and the least at 18:00 (3) Analysis results of daily data show that suitable meteorological conditions for rime are: foggy days and daily mean temperature between -8 and 2 ℃, daily mean humidity ≥ 80%, daily mean wind speed between 2 and 9 m/s. (4) The statistics of hourly data shows that rime formation is mainly affected by air temperature. There needs a period of ≤ 0 ℃ low temperature of more than 7 hours before the formation of rime. The suitable meteorological conditions for rime are foggy and the temperature being between -6 and 1 ℃, humidity ≥ 95%, wind speed between 2 and 11 m/s, which reflect well the critical conditions of rime formation.
Based on the daily and hourly surface meteorological observation data of Huangshan Station from 2004 to 2016, the temporal distribution and climatic conditions of rime are analyzed. The results show that: (1) The annual average number of rime days in Huangshan is 616, with obvious differences between years. The earliest day of rime was mainly in November and the latest day was mainly in March and April. The number of consecutive rime days is often 3 to 4 days, accounting for 40% of the total number. In each year there were continuous rime days of ≥ 10 days. (2) The rime appeared mainly from October to next April, of which the number of rime days from December to next March accounted for 898%. The monthly mean number of rime days is significantly negatively correlated with the monthly mean temperature. There was a certain daily change in rime, with the highest number at 09:00, and the least at 18:00 (3) Analysis results of daily data show that suitable meteorological conditions for rime are: foggy days and daily mean temperature between -8 and 2 ℃, daily mean humidity ≥ 80%, daily mean wind speed between 2 and 9 m/s. (4) The statistics of hourly data shows that rime formation is mainly affected by air temperature. There needs a period of ≤ 0 ℃ low temperature of more than 7 hours before the formation of rime. The suitable meteorological conditions for rime are foggy and the temperature being between -6 and 1 ℃, humidity ≥ 95%, wind speed between 2 and 11 m/s, which reflect well the critical conditions of rime formation.
2018, 46(6):1291-1296.
Abstract:
Based on the Lightning data obtained from the lightning location system in Hubei Province from 2007 to 2016, the evaluation model of lightning intensity is established after the statistical analysis of the characteristics of lightning current amplitude and lightning steepness. The lightning intensity is divided into four levels: weak (I), medium (II), strong (III) and extremely strong (IV) by using the method of symmetrical unequal interval, and the thresholds for each level are calculated. In addition to test the rationality of the classification threshold, a further inspection is also made with the thunder and lightning disaster data. The results show that the lightning intensity classification method is objective and feasible, which can provide references for lightning disaster assessment and classification, and lightning warning and forecasting.
Based on the Lightning data obtained from the lightning location system in Hubei Province from 2007 to 2016, the evaluation model of lightning intensity is established after the statistical analysis of the characteristics of lightning current amplitude and lightning steepness. The lightning intensity is divided into four levels: weak (I), medium (II), strong (III) and extremely strong (IV) by using the method of symmetrical unequal interval, and the thresholds for each level are calculated. In addition to test the rationality of the classification threshold, a further inspection is also made with the thunder and lightning disaster data. The results show that the lightning intensity classification method is objective and feasible, which can provide references for lightning disaster assessment and classification, and lightning warning and forecasting.
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.