Volume 48,Issue 4,2020 Table of Contents
2020, 48(4):451-458.
Abstract:
The mixing heights determined by the micropulse lidar and radiosonde profile data on sunny days (from December 2016 to November 2017) in Chengdu are compared. The error analysis of mixing heights based on lidar is made. The results show that: The mixing heights determined by micropulse lidar and radiosonde data have good consistency (the correlation coefficient is 0.75), which indicates that it is accurate to use the micropulse lidar data to invert the mixing heights in Chengdu. The mixing heights inverted by lidar data are slightly lower than the values determined by radiosonde data. The deviation of the values which are determined by the two methods is very small (about 20%) when the mixing height is from 1000 m to 2000 m. The deviation increases slightly (26%) when the mixing heights are lower than 1000 m or higher than 2000 m. The variation trend of mixing heights determined by the two methods is relatively consistent, which are lower in December and January, and higher in April and May. The mixing heights determined by lidar have obvious diurnal variation characteristics. The mixing heights increase rapidly in the morning and the growth rates slowdown in the afternoon. The mixing heights reach the maximum in the afternoon, and decrease rapidly after sunset. The increase of relative humidity and the existence of the residual layer are the reasons that lead to the large error in the inversion of the mixing layer height based on lidar data.
The mixing heights determined by the micropulse lidar and radiosonde profile data on sunny days (from December 2016 to November 2017) in Chengdu are compared. The error analysis of mixing heights based on lidar is made. The results show that: The mixing heights determined by micropulse lidar and radiosonde data have good consistency (the correlation coefficient is 0.75), which indicates that it is accurate to use the micropulse lidar data to invert the mixing heights in Chengdu. The mixing heights inverted by lidar data are slightly lower than the values determined by radiosonde data. The deviation of the values which are determined by the two methods is very small (about 20%) when the mixing height is from 1000 m to 2000 m. The deviation increases slightly (26%) when the mixing heights are lower than 1000 m or higher than 2000 m. The variation trend of mixing heights determined by the two methods is relatively consistent, which are lower in December and January, and higher in April and May. The mixing heights determined by lidar have obvious diurnal variation characteristics. The mixing heights increase rapidly in the morning and the growth rates slowdown in the afternoon. The mixing heights reach the maximum in the afternoon, and decrease rapidly after sunset. The increase of relative humidity and the existence of the residual layer are the reasons that lead to the large error in the inversion of the mixing layer height based on lidar data.
2020, 48(4):459-464.
Abstract:
The performance evaluation of the ground lightning location system can be achieved by theoretical simulation, and also by direct observations based on the facts of artificially triggered lightning or natural lightning. Due to the randomness and instantaneity of the occurrence of natural lightning, there are few direct observation facts. So far, the performance evaluation of the cloudtoground lightning location system based on the real return strokes of lightning happened naturally is still lacking. This study is based on the investigation of the lightning incident at Chaoshan Airport in Guangdong Province on 30 May 2016. The study evaluates the location performance of the ADTD cloudtoground lightning in the area, and at the same time calculates the location errors of different stations through the airport lightning incident with clear location. The results show that the ADTD lightning location system can accurately record the lightning events of Chaoshan Airport in real time, which shows its practicability and accuracy. Through the relocation calculation, it is found that the stations with larger errors can be removed in the multistation location, which can ensure the increased accuracy of location results， but the location results mentioned above may not be optimal.
The performance evaluation of the ground lightning location system can be achieved by theoretical simulation, and also by direct observations based on the facts of artificially triggered lightning or natural lightning. Due to the randomness and instantaneity of the occurrence of natural lightning, there are few direct observation facts. So far, the performance evaluation of the cloudtoground lightning location system based on the real return strokes of lightning happened naturally is still lacking. This study is based on the investigation of the lightning incident at Chaoshan Airport in Guangdong Province on 30 May 2016. The study evaluates the location performance of the ADTD cloudtoground lightning in the area, and at the same time calculates the location errors of different stations through the airport lightning incident with clear location. The results show that the ADTD lightning location system can accurately record the lightning events of Chaoshan Airport in real time, which shows its practicability and accuracy. Through the relocation calculation, it is found that the stations with larger errors can be removed in the multistation location, which can ensure the increased accuracy of location results， but the location results mentioned above may not be optimal.
2020, 48(4):465-473.
Abstract:
Based on Beijing and Tianjin CINRAD/SA volume scan data from precipitation cases in July 2012, the differences of radar reflectivity factors around the sample equaldistance crosssections of two nearby radars are analyzed. Results show that no systematic bias is found between two radar sets. There exists one degree azimuth angle shift revealed from the rotating data and correlation analyze. Sample pairs at the plain area have better consistency than those in the mountain area. Beside distance, different propagation paths, the attenuation of the atmosphere, clouds and rainfall, and the refraction that causes echo height change are also reasons leading to differences in the sample pairs.
Based on Beijing and Tianjin CINRAD/SA volume scan data from precipitation cases in July 2012, the differences of radar reflectivity factors around the sample equaldistance crosssections of two nearby radars are analyzed. Results show that no systematic bias is found between two radar sets. There exists one degree azimuth angle shift revealed from the rotating data and correlation analyze. Sample pairs at the plain area have better consistency than those in the mountain area. Beside distance, different propagation paths, the attenuation of the atmosphere, clouds and rainfall, and the refraction that causes echo height change are also reasons leading to differences in the sample pairs.
2020, 48(4):474-481.
Abstract:
Based on the precipitation data from 35 rain gauge stations of the southern Shandong Province and using the quantitative and classification score methods, the authors evaluate the applicability of GPM/IMERG products from time, space and rainfall intensity from January to December 2016. The results show that the IMERG data has high precision in the southern Shandong Province as a whole. The correlation coefficient between IMERG and site observation data is 0.8, the root mean square error is 5.47 mm/day, and the relative deviation is 2.27%. In terms of time, the IMERG data is consistent with the overall trend of average daily precipitation and monthly precipitation in the observation area of the site. The accuracy of the IMERG data in summer is better than those in other seasons. From a spatial point of view, the IMERG data will be underestimated in the areas with more annual precipitation, and overestimated in the areas with less annual precipitation. The IMERG data are more accurate in the midlatitude mountains and hill areas than those in plain in estimating. The estimation accuracy of IMERG products is related to rainfall intensity. When the precipitation level is microprecipitation (less than 1 mm/d), the IMERG estimation ability is weak. When the precipitation intensity is light rain and above, the difference between IMERG product and actual observed probability density is small. IMERG has a strong ability to estimate stable precipitation. In the months of more precipitation, the detection accuracy of IMERG is higher, the false alarm ratio is lower, and the critical success index is better.
Based on the precipitation data from 35 rain gauge stations of the southern Shandong Province and using the quantitative and classification score methods, the authors evaluate the applicability of GPM/IMERG products from time, space and rainfall intensity from January to December 2016. The results show that the IMERG data has high precision in the southern Shandong Province as a whole. The correlation coefficient between IMERG and site observation data is 0.8, the root mean square error is 5.47 mm/day, and the relative deviation is 2.27%. In terms of time, the IMERG data is consistent with the overall trend of average daily precipitation and monthly precipitation in the observation area of the site. The accuracy of the IMERG data in summer is better than those in other seasons. From a spatial point of view, the IMERG data will be underestimated in the areas with more annual precipitation, and overestimated in the areas with less annual precipitation. The IMERG data are more accurate in the midlatitude mountains and hill areas than those in plain in estimating. The estimation accuracy of IMERG products is related to rainfall intensity. When the precipitation level is microprecipitation (less than 1 mm/d), the IMERG estimation ability is weak. When the precipitation intensity is light rain and above, the difference between IMERG product and actual observed probability density is small. IMERG has a strong ability to estimate stable precipitation. In the months of more precipitation, the detection accuracy of IMERG is higher, the false alarm ratio is lower, and the critical success index is better.
2020, 48(4):482-489.
Abstract:
In order to realize the comprehensive health evaluation of the polar orbiting meteorological satellite application system, the comprehensive weight of the index value of the system to be evaluated is determined by combining the Analytic Hierarchy Process (AHP) of subjective analysis and the entropy weight (EW) of objective analysis, then the TOPSIS (Technique for Order Preference by Similarity to an Ideal Solution) is used to rank the indexes of the system from multiple angles as the final evaluation result. In this paper, three polar orbiting meteorological satellites in five consecutive months are used to analyze the abnormal index samples in the actual operation system. The results show that this method considers many factors that affect the application system comprehensively, avoids the limitation of single criterion, and makes a comprehensive comparative analysis of the importance of each index, making the evaluation results more scientific and accurate, and it can be used as a method for the health evaluation of the polar orbiting meteorological satellite application system.
In order to realize the comprehensive health evaluation of the polar orbiting meteorological satellite application system, the comprehensive weight of the index value of the system to be evaluated is determined by combining the Analytic Hierarchy Process (AHP) of subjective analysis and the entropy weight (EW) of objective analysis, then the TOPSIS (Technique for Order Preference by Similarity to an Ideal Solution) is used to rank the indexes of the system from multiple angles as the final evaluation result. In this paper, three polar orbiting meteorological satellites in five consecutive months are used to analyze the abnormal index samples in the actual operation system. The results show that this method considers many factors that affect the application system comprehensively, avoids the limitation of single criterion, and makes a comprehensive comparative analysis of the importance of each index, making the evaluation results more scientific and accurate, and it can be used as a method for the health evaluation of the polar orbiting meteorological satellite application system.
2020, 48(4):490-495.
Abstract:
For the convenience for the meteorological personnel in the multiangle observation of radar echo in details and the spatial distribution, this paper proposes and implements a crossplatform interactive 3D visualization analysis platform of Doppler weather radar. This paper proposes a visualization algorithm based on the characteristics of radarbased data. Based on the B/S mode, the overall architecture and design of multidimensional visual analysis platform are realized. The twodimensional and threedimensional visual display of the Webbased radar echoes is realized by using HTML Canvas technology and WebGL technology. The experimental results show that the Doppler weather radar 3D visualization analysis platform performs well in 3D visualization and interactive visual experiences and provides an effective visual analysis tool for meteorologists.
For the convenience for the meteorological personnel in the multiangle observation of radar echo in details and the spatial distribution, this paper proposes and implements a crossplatform interactive 3D visualization analysis platform of Doppler weather radar. This paper proposes a visualization algorithm based on the characteristics of radarbased data. Based on the B/S mode, the overall architecture and design of multidimensional visual analysis platform are realized. The twodimensional and threedimensional visual display of the Webbased radar echoes is realized by using HTML Canvas technology and WebGL technology. The experimental results show that the Doppler weather radar 3D visualization analysis platform performs well in 3D visualization and interactive visual experiences and provides an effective visual analysis tool for meteorologists.
2020, 48(4):496-502.
Abstract:
The useroriented meteorological data services are becoming the current service mode, which calls for a model transition from the previous dataoriented types. In the past, the data acquisition and data filtering are very laborintensive and timeconsuming. To address this problem, we provide a new meteorological data service system combining with the meteorological data service interface and WebGIS technology, which can significantly simplify the user operation and enhance the system performance. Specifically, the proposed system enables users to easily filter specific stations, accomplish geospatial analysis, retrieve and download data through the Meteorological Unified Service Interface Community (MUSIC) in the National Meteorological Business Intranet Platform, which effectively improves the user experience.
The useroriented meteorological data services are becoming the current service mode, which calls for a model transition from the previous dataoriented types. In the past, the data acquisition and data filtering are very laborintensive and timeconsuming. To address this problem, we provide a new meteorological data service system combining with the meteorological data service interface and WebGIS technology, which can significantly simplify the user operation and enhance the system performance. Specifically, the proposed system enables users to easily filter specific stations, accomplish geospatial analysis, retrieve and download data through the Meteorological Unified Service Interface Community (MUSIC) in the National Meteorological Business Intranet Platform, which effectively improves the user experience.
2020, 48(4):503-510.
Abstract:
For the visual meteorological support services of Yangtze River shipping, in this paper, the Weather Navigation Grade is designed to represent the influence of weather on shipping, and the algorithm of the Weather Navigation Grade under two service scenarios is given, using the weather monitoring, grid forecast and service warning along the Yangtze River, applied to calculate the shipping dispatching management and ship schedule planning. The method of applying the Weather Navigation Grade to intelligent navigation meteorological service is described. This paper introduces the overall design, main products, system functions and main characteristics of the Yangtze River shipping meteorological forecast and early warning service system based on the Weather Navigation Grade, combined with the development of shipping meteorological service, and the future improvement direction of the system is discussed.
For the visual meteorological support services of Yangtze River shipping, in this paper, the Weather Navigation Grade is designed to represent the influence of weather on shipping, and the algorithm of the Weather Navigation Grade under two service scenarios is given, using the weather monitoring, grid forecast and service warning along the Yangtze River, applied to calculate the shipping dispatching management and ship schedule planning. The method of applying the Weather Navigation Grade to intelligent navigation meteorological service is described. This paper introduces the overall design, main products, system functions and main characteristics of the Yangtze River shipping meteorological forecast and early warning service system based on the Weather Navigation Grade, combined with the development of shipping meteorological service, and the future improvement direction of the system is discussed.
2020, 48(4):511-517.
Abstract:
The calculation schemes of the postprocessing system of the GRAEPS model are studied in detail, and the sea level pressure calculation scheme and the temperature vertical interpolation scheme in the GRAPES postprocessing system, and the extrapolation scheme in the vertical interpolation of potential height are improved. GRAPES mostly adopts the cubic spline function method to vertical interpolation, and the interpolation precision can be guaranteed. However, the sea level pressure calculation scheme and the extrapolation scheme below the terrain in the previous GRAPES postprocessing system is not detailed enough. In this paper, assuming that the temperature profile varied with terrain height and the model atmosphere satisfied the static equilibrium condition, the sea level pressure calculation scheme and the original interpolation layer of sea level pressure and temperature used for vertical interpolation is optimized, so that the accuracy of sea level pressure and highlevel temperature is further improved. The statistical test scores are improved in different regions, and the sea level pressure and the highlevel temperature field in the tropics and East Asia improved significantly and passed the significance test. The extrapolation schemes of potential height are optimized, and the lowlevel potential heights are improved significantly in large terrains such as the QinghaiTibet Plateau and the western South America. Statistical results show that this scheme has significant improvements in the anomaly correlation coefficient and root mean square error in the lowlevel fields in various regions of the world. These provide more reliable numerical model products for users.
The calculation schemes of the postprocessing system of the GRAEPS model are studied in detail, and the sea level pressure calculation scheme and the temperature vertical interpolation scheme in the GRAPES postprocessing system, and the extrapolation scheme in the vertical interpolation of potential height are improved. GRAPES mostly adopts the cubic spline function method to vertical interpolation, and the interpolation precision can be guaranteed. However, the sea level pressure calculation scheme and the extrapolation scheme below the terrain in the previous GRAPES postprocessing system is not detailed enough. In this paper, assuming that the temperature profile varied with terrain height and the model atmosphere satisfied the static equilibrium condition, the sea level pressure calculation scheme and the original interpolation layer of sea level pressure and temperature used for vertical interpolation is optimized, so that the accuracy of sea level pressure and highlevel temperature is further improved. The statistical test scores are improved in different regions, and the sea level pressure and the highlevel temperature field in the tropics and East Asia improved significantly and passed the significance test. The extrapolation schemes of potential height are optimized, and the lowlevel potential heights are improved significantly in large terrains such as the QinghaiTibet Plateau and the western South America. Statistical results show that this scheme has significant improvements in the anomaly correlation coefficient and root mean square error in the lowlevel fields in various regions of the world. These provide more reliable numerical model products for users.
2020, 48(4):518-528.
Abstract:
Based on the surface energy balance method and the soil temperature calculation module of the Community Land Model (CLM), a numerical forecast model for road surface temperature on expressway is developed. The hourly observation data of 8 conventional meteorological stations and 6 traffic automatic weather monitoring stations from 1 June 2014 to 31 May 2015 are used to evaluate and test the model forecast products. The results show that the prediction skill increases with the decrease of forecast lead time. When the forecast lead time is 1 and 6 hours, the average absolute errors of the conventional stations (traffic stations) are 1.64 ℃ (1.82 ℃) and 3.27 ℃ (3.69 ℃), respectively. The sensitivity analysis of the model to the meteorological elements indicates that the model is most sensitive to 2m temperature, followed by relative humidity and total cloud amount, and the sensitivity increases with the increase of forecast lead time. Combined with the forecasting products of the Zhejiang WRFADAS Rapid Refresh System, the Zhejiang Expressway Surface Temperature Forecasting System is established to provide the refined forecasting products of hourly highway surface temperature in the future 12 hours with an update rate of 12 hours for the whole province. The evaluation results show that the average absolute errors of conventional stations (traffic stations) are 2.81 ℃ (3.23 ℃) and 2.50 ℃ (2.93 ℃), respectively, when the forecast lead time are 1 and 11 hours. The system has high forecasting skills for extreme high (low) temperature forecasting.
Based on the surface energy balance method and the soil temperature calculation module of the Community Land Model (CLM), a numerical forecast model for road surface temperature on expressway is developed. The hourly observation data of 8 conventional meteorological stations and 6 traffic automatic weather monitoring stations from 1 June 2014 to 31 May 2015 are used to evaluate and test the model forecast products. The results show that the prediction skill increases with the decrease of forecast lead time. When the forecast lead time is 1 and 6 hours, the average absolute errors of the conventional stations (traffic stations) are 1.64 ℃ (1.82 ℃) and 3.27 ℃ (3.69 ℃), respectively. The sensitivity analysis of the model to the meteorological elements indicates that the model is most sensitive to 2m temperature, followed by relative humidity and total cloud amount, and the sensitivity increases with the increase of forecast lead time. Combined with the forecasting products of the Zhejiang WRFADAS Rapid Refresh System, the Zhejiang Expressway Surface Temperature Forecasting System is established to provide the refined forecasting products of hourly highway surface temperature in the future 12 hours with an update rate of 12 hours for the whole province. The evaluation results show that the average absolute errors of conventional stations (traffic stations) are 2.81 ℃ (3.23 ℃) and 2.50 ℃ (2.93 ℃), respectively, when the forecast lead time are 1 and 11 hours. The system has high forecasting skills for extreme high (low) temperature forecasting.
2020, 48(4):529-536.
Abstract:
The Xujiahui district of Shanghai is a typical nonhomogeneous urban terrain, with densely distributed architectures of different heights. In this paper, the distribution characteristics of roughness length are studied by using the geographic information of this area. Based on the measured wind data at the height of 80 m, the relationships among the mean wind velocity, turbulence intensity, gust factor and roughness length under the Typhoon Chanhom and the normal wind are analyzed. The results show that the differences of building heights and distribution densities in the calculated sectors corresponding to different wind directions led to the obvious variation of roughness length with wind direction, but the variation amplitude decreased with the increase of calculated sectors. The maximum value of mean wind velocity under Typhoon Chanhom was larger than that under normal winds, and there was little difference in the range of roughness length variation, but the median value of the roughness length under Typhoon Chanhom was small and the distribution was relatively concentrated. Under Typhoon Chanhom, the turbulence intensity in all directions decreased with the increase of mean wind velocity, but did not change with the roughness length. Under normal wind, the turbulence intensity in each direction does not change with the mean wind velocity, but increases with the increase of roughness length. Under typhoon Chanhom and normal wind, the gust factor in all directions increases with the increase of turbulence intensity, but the former values are slightly larger than the latter.
The Xujiahui district of Shanghai is a typical nonhomogeneous urban terrain, with densely distributed architectures of different heights. In this paper, the distribution characteristics of roughness length are studied by using the geographic information of this area. Based on the measured wind data at the height of 80 m, the relationships among the mean wind velocity, turbulence intensity, gust factor and roughness length under the Typhoon Chanhom and the normal wind are analyzed. The results show that the differences of building heights and distribution densities in the calculated sectors corresponding to different wind directions led to the obvious variation of roughness length with wind direction, but the variation amplitude decreased with the increase of calculated sectors. The maximum value of mean wind velocity under Typhoon Chanhom was larger than that under normal winds, and there was little difference in the range of roughness length variation, but the median value of the roughness length under Typhoon Chanhom was small and the distribution was relatively concentrated. Under Typhoon Chanhom, the turbulence intensity in all directions decreased with the increase of mean wind velocity, but did not change with the roughness length. Under normal wind, the turbulence intensity in each direction does not change with the mean wind velocity, but increases with the increase of roughness length. Under typhoon Chanhom and normal wind, the gust factor in all directions increases with the increase of turbulence intensity, but the former values are slightly larger than the latter.
2020, 48(4):537-541.
Abstract:
Based on hail data from 24 meteorological stations in Ningxia during 1961-2018, the spatial and temporal characteristics of hail days are studied. The results display that there were more hail days in Ningxia from the 1960s to the 1980s. The hails mainly occur in summer and autumn, but the occurrence time is different in different regions. The hails in the area irrigated by the Yellow River in the north belong to the type of occurring frequently in summer, while the hails in the central and southern parts belong to the type of occurring frequently in late spring and early summer. The peak periods of the two types of hails differ by about one month. More than 90 percent of the hails occur between 12:00 and 20:00. The spatial and temporal distribution is generally characterized by more in the plateau and mountainous areas and less in the low plain and desert areas.
Based on hail data from 24 meteorological stations in Ningxia during 1961-2018, the spatial and temporal characteristics of hail days are studied. The results display that there were more hail days in Ningxia from the 1960s to the 1980s. The hails mainly occur in summer and autumn, but the occurrence time is different in different regions. The hails in the area irrigated by the Yellow River in the north belong to the type of occurring frequently in summer, while the hails in the central and southern parts belong to the type of occurring frequently in late spring and early summer. The peak periods of the two types of hails differ by about one month. More than 90 percent of the hails occur between 12:00 and 20:00. The spatial and temporal distribution is generally characterized by more in the plateau and mountainous areas and less in the low plain and desert areas.
2020, 48(4):542-553.
Abstract:
Using various data such as conventional observation data, radar and satellite data, reanalysis data from EC and realtime global sea surface temperature data from NCEP, the environmental conditions of a hail event on 3 March 2018 in Hainan are compared and examined and the its mesoscale features are analyzed. The results show that largescale circulations were depicted with a midlevel drycold WSW jet, lowlevel warm SW flows and the surface southwest trough from 2 to 4 March. On 3 March, the regional atmospheric stratification was in a transition from stable to unstable. The local increased unstable energy was strongly released by the trigger of seabreeze front. The favorable 0to6 km vertical wind shear, 0 ℃ and 20 ℃ heights are conducive to the development of the hailstorm. On 2 March, the regional stratification near the Hainan Island was stable and the CAPE value was low; on 4 March, the Hainan Island was at the entrance of the lowlevel gale core with divergent water vapor, and the vertical circulation of the seabreeze front was restrained. Those were unfavorable for the development of severe convections. This hailstorm had some typical radar characteristics. After the hailstorm moving into the static cone areas of Doppler radar, the downtoward propagation of highlevel jet pulse and the increase of the vertical wind shear of 0 to 5 km and 0 to 3 km can be detected by utilizing the wind profile radar, which is of great significance to the judgment of the evolution of the storm cell. The convective cell initially appeared at the junction of the surface convergent line and the dew point front in the central Danzhou, and developed into a hailstorm in the overlapping areas of the northside of the sea breeze front and the dew point front in the north of Haikou to Danzhou. New cells developed around the dew point front at the front of the hailstorm.
Using various data such as conventional observation data, radar and satellite data, reanalysis data from EC and realtime global sea surface temperature data from NCEP, the environmental conditions of a hail event on 3 March 2018 in Hainan are compared and examined and the its mesoscale features are analyzed. The results show that largescale circulations were depicted with a midlevel drycold WSW jet, lowlevel warm SW flows and the surface southwest trough from 2 to 4 March. On 3 March, the regional atmospheric stratification was in a transition from stable to unstable. The local increased unstable energy was strongly released by the trigger of seabreeze front. The favorable 0to6 km vertical wind shear, 0 ℃ and 20 ℃ heights are conducive to the development of the hailstorm. On 2 March, the regional stratification near the Hainan Island was stable and the CAPE value was low; on 4 March, the Hainan Island was at the entrance of the lowlevel gale core with divergent water vapor, and the vertical circulation of the seabreeze front was restrained. Those were unfavorable for the development of severe convections. This hailstorm had some typical radar characteristics. After the hailstorm moving into the static cone areas of Doppler radar, the downtoward propagation of highlevel jet pulse and the increase of the vertical wind shear of 0 to 5 km and 0 to 3 km can be detected by utilizing the wind profile radar, which is of great significance to the judgment of the evolution of the storm cell. The convective cell initially appeared at the junction of the surface convergent line and the dew point front in the central Danzhou, and developed into a hailstorm in the overlapping areas of the northside of the sea breeze front and the dew point front in the north of Haikou to Danzhou. New cells developed around the dew point front at the front of the hailstorm.
2020, 48(4):554-560.
Abstract:
Based on the historical data of MICAPS, the circulation patterns of 12 hailstorms in Nanning since 2000 are classified into 3 types: the elevated (6), plateau trough (3), and SouthWest cyclone (3). The weather background, the physical factor field, and the radar product output of the three hailstorms taking place on 4 April 2009, 18 March 2017, and 7 May 2018 are analyzed by using the data from the radiosonde observation, the MICAPS data, and the Doppler radar products in Nanning. The conclusions are as follows: (1) The existence of the SouthWest cyclone plays an important role in the occurrence of hailstorms in Nanning. (2) The unstable atmospheric stratification, strong vertical wind shear, and suitable heights of 0 ℃ and 20 ℃ isotherms are the necessary conditions for hail weather in Nanning. (3) The jump of vertical liquid water content is an important means to judge whether a hail occurs or not in Nanning.
Based on the historical data of MICAPS, the circulation patterns of 12 hailstorms in Nanning since 2000 are classified into 3 types: the elevated (6), plateau trough (3), and SouthWest cyclone (3). The weather background, the physical factor field, and the radar product output of the three hailstorms taking place on 4 April 2009, 18 March 2017, and 7 May 2018 are analyzed by using the data from the radiosonde observation, the MICAPS data, and the Doppler radar products in Nanning. The conclusions are as follows: (1) The existence of the SouthWest cyclone plays an important role in the occurrence of hailstorms in Nanning. (2) The unstable atmospheric stratification, strong vertical wind shear, and suitable heights of 0 ℃ and 20 ℃ isotherms are the necessary conditions for hail weather in Nanning. (3) The jump of vertical liquid water content is an important means to judge whether a hail occurs or not in Nanning.
2020, 48(4):561-569.
Abstract:
The meteorological factors directly affecting aircraft icing are air temperature, supercooled water content and the size of supercooled water droplets. The researches on the meteorological factors of aircraft icing are of great significance for flight safety assurance, aircraft airworthiness verification, weather modification and so on. In recent years, remarkable advances in the researches on this topic have been reported. A briefly comprehensive review for the advances in the researches on aircraft icing conditions is presented, which includes airborne observations, weather systems, satellite retrievals, forecast, and climate characteristics, as well as some related issues. The results of aircraft detection show that the temporal and spatial distribution of supercooled water is obviously uneven. On the basis of a large number of aircraft icing observation tests abroad, the icing environment is statistically analyzed, and a series of standards for aircraft icing airworthiness verification are formulated. The main weather systems that produce aircraft icing include the fronts, high troughs, and shear lines, and freezing rain often produces strong icing. It is the main trend to develop aircraft icing area recognition technology by integrating the advantages of multisource remote sensing data. The mesoscale model with the ability to predict cloud water explicitly provides a better tool for predicting aircraft icing. At the same time, the realtime ice potential system which integrates multiple monitoring data and model data is a new development direction.
The meteorological factors directly affecting aircraft icing are air temperature, supercooled water content and the size of supercooled water droplets. The researches on the meteorological factors of aircraft icing are of great significance for flight safety assurance, aircraft airworthiness verification, weather modification and so on. In recent years, remarkable advances in the researches on this topic have been reported. A briefly comprehensive review for the advances in the researches on aircraft icing conditions is presented, which includes airborne observations, weather systems, satellite retrievals, forecast, and climate characteristics, as well as some related issues. The results of aircraft detection show that the temporal and spatial distribution of supercooled water is obviously uneven. On the basis of a large number of aircraft icing observation tests abroad, the icing environment is statistically analyzed, and a series of standards for aircraft icing airworthiness verification are formulated. The main weather systems that produce aircraft icing include the fronts, high troughs, and shear lines, and freezing rain often produces strong icing. It is the main trend to develop aircraft icing area recognition technology by integrating the advantages of multisource remote sensing data. The mesoscale model with the ability to predict cloud water explicitly provides a better tool for predicting aircraft icing. At the same time, the realtime ice potential system which integrates multiple monitoring data and model data is a new development direction.
2020, 48(4):570-578.
Abstract:
Based on the intensive observation data, the spatial distribution and temporal evolution characteristics of the thermal environment in the main urban area of Hangzhou are revealed. The results show that the effect of urban heat island is the strongest in autumn and winter, the weaker in spring, and the weakest in summer. The most parts of Jianggan, Xiaoshan and Shangcheng are the main highvalue areas of heat island intensity with the annual average more than 0.50 ℃. The peak value can achieve 0.75 ℃ and above in autumn, and over 0.50 ℃ in the other seasons. The high value zone is the largest in winter and the smallest in summer, and the urban heat island effect in Hangzhou tends to expand from the old city to the new city. The urban heat island effect in Hangzhou is strong at night and weak during the daytime with the heat island intensity more than 1.00 ℃ in the high value center at 02:00, then down to 0.50 to 0.75 ℃ at 08:00. The whole city are almost 0.00 to 0.25 ℃ at 14:00, and the maximum reaches more than 0.75 ℃ at 20:00. It is more likely to be muggy in the urban area than in the suburbs, to a greater degree, but the disparity between urban and rural areas has been narrowing in recent years.
Based on the intensive observation data, the spatial distribution and temporal evolution characteristics of the thermal environment in the main urban area of Hangzhou are revealed. The results show that the effect of urban heat island is the strongest in autumn and winter, the weaker in spring, and the weakest in summer. The most parts of Jianggan, Xiaoshan and Shangcheng are the main highvalue areas of heat island intensity with the annual average more than 0.50 ℃. The peak value can achieve 0.75 ℃ and above in autumn, and over 0.50 ℃ in the other seasons. The high value zone is the largest in winter and the smallest in summer, and the urban heat island effect in Hangzhou tends to expand from the old city to the new city. The urban heat island effect in Hangzhou is strong at night and weak during the daytime with the heat island intensity more than 1.00 ℃ in the high value center at 02:00, then down to 0.50 to 0.75 ℃ at 08:00. The whole city are almost 0.00 to 0.25 ℃ at 14:00, and the maximum reaches more than 0.75 ℃ at 20:00. It is more likely to be muggy in the urban area than in the suburbs, to a greater degree, but the disparity between urban and rural areas has been narrowing in recent years.
2020, 48(4):579-589.
Abstract:
The existing comprehensive risk assessments of storms and floods in many cities in China often underestimate the risks caused by torrential rains and geological disasters induced by heavy rains in complex terrain area and insufficient estimates of urban traffic safety risks. At the same time, due to the influence of terrain and urban heat islands, the geographical spatial characteristics of heavy rains are obvious. It is difficult to describe the spatial distribution of storm hazard risks by the conventional meteorological observation data. Based on the theory of natural disaster risk assessment, this paper uses the yeartoyear precipitation observation data of 293 meteorological automatic stations in Beijing from 2006 to 2017, the 1〖DK〗∶25×104 basic geographic information in 2015, the Landsat8 clearsky remote sensing images in 2016, disaster data, as well as other socioeconomic aids. The shortduration rainstorm frequency and rainstorm process rainfall indicators are used to assess the risk of rainstorm disasters. Based on the topography and river network factors, the impervious coverage index is introduced to reflect the environmental sensitivity of the disasterstricken environment. Based on the exposure of the hazardbearing body, the study fully considers the sensitivity difference of the disasterstricken body to the urban floods, mountain torrents and geological disasters caused by heavy rainfall. From the respects of the risk of rainstorm disasters, the sensitivity of the environment to the disasters, and the vulnerability of the disaster victims, a fine comprehensive risk zoning with a resolution of 1 km is carried out for the heavy rain disasters in Beijing, and the actual case was analyzed. The results show that: (1) The gridded shortduration rainstorm frequency and the heavy rain amount based on the highdensity precipitation observation data can be used to evaluate the hazard risk more accurately; the impervious cover, terrain relief and river network density based on remote sensing and GIS extraction can be used to effectively assess the environmental sensitivity of storm floods and floods; based on 1km grid GDP, population density, road network density and damage sensitivity coefficient can be used to effectively assess the vulnerability of the rainstorminduced waterlogging, mountain torrents and geological disasters on people, property and road traffic. (2) Compared with the existing results, the Beijing torrential rain flood risk zoning highlights the waterlogging of heavy rains on the city, the risk of flash floods and geological disasters caused by heavy rains, and the impact of heavy rains on the safety of urban transport facilities. (3) The results of risk zoning basically reflect the potential risks of heavy rain disasters in Beijing. The key areas of storm flooding disaster prevention in Beijing should be placed in three areas with high risk.
The existing comprehensive risk assessments of storms and floods in many cities in China often underestimate the risks caused by torrential rains and geological disasters induced by heavy rains in complex terrain area and insufficient estimates of urban traffic safety risks. At the same time, due to the influence of terrain and urban heat islands, the geographical spatial characteristics of heavy rains are obvious. It is difficult to describe the spatial distribution of storm hazard risks by the conventional meteorological observation data. Based on the theory of natural disaster risk assessment, this paper uses the yeartoyear precipitation observation data of 293 meteorological automatic stations in Beijing from 2006 to 2017, the 1〖DK〗∶25×104 basic geographic information in 2015, the Landsat8 clearsky remote sensing images in 2016, disaster data, as well as other socioeconomic aids. The shortduration rainstorm frequency and rainstorm process rainfall indicators are used to assess the risk of rainstorm disasters. Based on the topography and river network factors, the impervious coverage index is introduced to reflect the environmental sensitivity of the disasterstricken environment. Based on the exposure of the hazardbearing body, the study fully considers the sensitivity difference of the disasterstricken body to the urban floods, mountain torrents and geological disasters caused by heavy rainfall. From the respects of the risk of rainstorm disasters, the sensitivity of the environment to the disasters, and the vulnerability of the disaster victims, a fine comprehensive risk zoning with a resolution of 1 km is carried out for the heavy rain disasters in Beijing, and the actual case was analyzed. The results show that: (1) The gridded shortduration rainstorm frequency and the heavy rain amount based on the highdensity precipitation observation data can be used to evaluate the hazard risk more accurately; the impervious cover, terrain relief and river network density based on remote sensing and GIS extraction can be used to effectively assess the environmental sensitivity of storm floods and floods; based on 1km grid GDP, population density, road network density and damage sensitivity coefficient can be used to effectively assess the vulnerability of the rainstorminduced waterlogging, mountain torrents and geological disasters on people, property and road traffic. (2) Compared with the existing results, the Beijing torrential rain flood risk zoning highlights the waterlogging of heavy rains on the city, the risk of flash floods and geological disasters caused by heavy rains, and the impact of heavy rains on the safety of urban transport facilities. (3) The results of risk zoning basically reflect the potential risks of heavy rain disasters in Beijing. The key areas of storm flooding disaster prevention in Beijing should be placed in three areas with high risk.
2020, 48(4):590-599.
Abstract:
Under the background of global warming and rapid urbanization, the urban heat island effect is the most obvious feature of urban thermal environment, so it is of great significance to study the temporal and spatial evolution of urban thermal environment change for disaster prevention and mitigation. In this study, we use the random forest model to estimate the spatial distribution of population in the Yangtze River Delta by taking the latest generation of night light satellite NPP/VIIRS data, the normalized vegetation index, the digital elevation model and topographic slope data as independent variables. Then we combine the surface temperature data retrieved by MODIS satellite remote sensing, taking the summer of 2016 as an example, to study the risk of surface thermal environment exposure and its special distribution in the Yangtze River Delta at 1 km resolution. The results show: (1) The explanatory degree of 1000 m grid spatialization variables for the population of the Yangtze River Delta in 2016 is 81.61% by using the random forest model. The simulated population can truly reflect the regional difference of population distribution in the Yangtze River Delta, closer to those of actual population. (2) The highvalue area of population density has a good correspondence with the hightemperature areas in the surface, the high populaton exposure areas and the highrisk areas exposed in most months of the summer, while in June, the area of hightemperature zone in the northwestern part of the Yangtze River Delta increased, which is asymmetrical to the area of highdensity population, and thus the exposure risks of surface temperature from low to high levels are higher than those in other months. (3) On monthly and seasonal scales, the high risks for population exposure to the land surface thermal environment are mainly located in the coastal areas, along the lower reaches of the Yangtze River and in the central urban areas of the counties. The middle risks for population exposure to LST is mainly distributed in the surrounding areas of the eastern and central cities; the lowexposure risk areas are distributed in the inland areas of the northeast and the relatively small population areas of the northeast Yangtze River Delta.
Under the background of global warming and rapid urbanization, the urban heat island effect is the most obvious feature of urban thermal environment, so it is of great significance to study the temporal and spatial evolution of urban thermal environment change for disaster prevention and mitigation. In this study, we use the random forest model to estimate the spatial distribution of population in the Yangtze River Delta by taking the latest generation of night light satellite NPP/VIIRS data, the normalized vegetation index, the digital elevation model and topographic slope data as independent variables. Then we combine the surface temperature data retrieved by MODIS satellite remote sensing, taking the summer of 2016 as an example, to study the risk of surface thermal environment exposure and its special distribution in the Yangtze River Delta at 1 km resolution. The results show: (1) The explanatory degree of 1000 m grid spatialization variables for the population of the Yangtze River Delta in 2016 is 81.61% by using the random forest model. The simulated population can truly reflect the regional difference of population distribution in the Yangtze River Delta, closer to those of actual population. (2) The highvalue area of population density has a good correspondence with the hightemperature areas in the surface, the high populaton exposure areas and the highrisk areas exposed in most months of the summer, while in June, the area of hightemperature zone in the northwestern part of the Yangtze River Delta increased, which is asymmetrical to the area of highdensity population, and thus the exposure risks of surface temperature from low to high levels are higher than those in other months. (3) On monthly and seasonal scales, the high risks for population exposure to the land surface thermal environment are mainly located in the coastal areas, along the lower reaches of the Yangtze River and in the central urban areas of the counties. The middle risks for population exposure to LST is mainly distributed in the surrounding areas of the eastern and central cities; the lowexposure risk areas are distributed in the inland areas of the northeast and the relatively small population areas of the northeast Yangtze River Delta.
2020, 48(4):600-606.
Abstract:
Grain weight is the most important factor of yield. Based on the summer maize field moisture control experiments from 2013 to 2015 in Gucheng, the EcologicalMeteorological Integrated Observation Experiment Station, Hebei Province, the natural environment is simulated by multiple scenarios, and the change characteristics of grain weight per spike of summer maize with the development stage (DVS) under watersufficient conditions are studied. As the experiment designed, the water at the three major development stages of summer maize, i.e., emerging to jointing, jointing to tasseling, tasseling to maturity, as well as (emerging to jointing)+(jointing to tasseling), (emerging to jointing)+ tasseling to maturity), and (jointing to tasseling)+(tasseling to maturity), are controlled in turn. By comparing the yield changes between different water treatments, the effects of different durations, different developmental stages and different degrees of water stress on yields are analyzed. The quantitative relationship models between soil relative humidity and yields under different water stresses are established. The results show that under the condition without soil water stress, the kernel weight of summer maize shows a “slowfastslow” growth characteristic with the increase of DVS. During the period from milk ripening to 10 days after milk ripening, the increase range and rate of grain weight are the largest. When water stress occurred from 10 days after tasseling to the stage of milk maturity, the grain weight decreased most. When water stress occurred in the emerging to jointing (stageⅠ), jointing to tasseling (stageⅡ), tasseling to maturity (stage Ⅲ), ［stageⅠ+stageⅡ］ and ［stageⅡ+stage Ⅲ］, the yield of summer maize had a significant linear positive relationship with soil relative humidity in five different periods separately. The relationship model shows that the more severe the water stress and the longer the duration, the greater the reduction in yield is. The effects of water stress on yield at the same level, different stages and different durations are as follows: ［stage II+stage III］ > ［stage I+stage II］ > stage III > stage II > stage I. In the five water treatment scenarios, soil relative humidity went down by 10%, the grain weight reduced 89.7 g/m2、122.7 g/m2、129.8 g/m2、133.7 g/m2 and 144.4 g/m2, respectively, a reduction of 228% to 36.8%.
Grain weight is the most important factor of yield. Based on the summer maize field moisture control experiments from 2013 to 2015 in Gucheng, the EcologicalMeteorological Integrated Observation Experiment Station, Hebei Province, the natural environment is simulated by multiple scenarios, and the change characteristics of grain weight per spike of summer maize with the development stage (DVS) under watersufficient conditions are studied. As the experiment designed, the water at the three major development stages of summer maize, i.e., emerging to jointing, jointing to tasseling, tasseling to maturity, as well as (emerging to jointing)+(jointing to tasseling), (emerging to jointing)+ tasseling to maturity), and (jointing to tasseling)+(tasseling to maturity), are controlled in turn. By comparing the yield changes between different water treatments, the effects of different durations, different developmental stages and different degrees of water stress on yields are analyzed. The quantitative relationship models between soil relative humidity and yields under different water stresses are established. The results show that under the condition without soil water stress, the kernel weight of summer maize shows a “slowfastslow” growth characteristic with the increase of DVS. During the period from milk ripening to 10 days after milk ripening, the increase range and rate of grain weight are the largest. When water stress occurred from 10 days after tasseling to the stage of milk maturity, the grain weight decreased most. When water stress occurred in the emerging to jointing (stageⅠ), jointing to tasseling (stageⅡ), tasseling to maturity (stage Ⅲ), ［stageⅠ+stageⅡ］ and ［stageⅡ+stage Ⅲ］, the yield of summer maize had a significant linear positive relationship with soil relative humidity in five different periods separately. The relationship model shows that the more severe the water stress and the longer the duration, the greater the reduction in yield is. The effects of water stress on yield at the same level, different stages and different durations are as follows: ［stage II+stage III］ > ［stage I+stage II］ > stage III > stage II > stage I. In the five water treatment scenarios, soil relative humidity went down by 10%, the grain weight reduced 89.7 g/m2、122.7 g/m2、129.8 g/m2、133.7 g/m2 and 144.4 g/m2, respectively, a reduction of 228% to 36.8%.
2020, 48(4):607-614.
Abstract:
In order to grasp the netizens’ attention to weather and tourism, the relationship between weather and tourism is analyzed. Based on the daily meteorological observation data of Changsha National Meteorological Station from 2012 to 2018 and Baidu Indexes as network attention, this study analyzes the meteorological factors such as temperature, precipitation, relative humidity, sunshine hours and Changsha Weather Network attention, Changsha global tourism network attention and Changsha rural travel network attention by using trend analysis and linear fitting. The results show that mobile users are the main focus of network attention; Changsha Weather network attention is significantly correlated with the lowest temperature, relative humidity, wind speed, sunshine hours, and precipitation; the probability and frequency of news headlines in the weather of drastical cooling, continuous rainstorm process, lightning warning and so on are large; and the network attention of the whole Changsha tourism is significantly correlated with average temperature, maximum temperature, minimum temperature, wind speed and relative humidity; the network attention of rural tourism is significantly correlated with temperature and precipitation; the network attention of Changsha weather, the whole Changsha tourism is on the rise, but the network attention Changsha rural tourism is on the decline; Changsha Weather Network attention is on the decline; Changsha Weather Network attention is on the rise. Local users account for 66.4%, followed by Beijing, Guangzhou, Shenzhen and Chengdu. The number of tourists is obviously affected by average temperature, average maximum temperature, average minimum temperature and sunshine hours.
In order to grasp the netizens’ attention to weather and tourism, the relationship between weather and tourism is analyzed. Based on the daily meteorological observation data of Changsha National Meteorological Station from 2012 to 2018 and Baidu Indexes as network attention, this study analyzes the meteorological factors such as temperature, precipitation, relative humidity, sunshine hours and Changsha Weather Network attention, Changsha global tourism network attention and Changsha rural travel network attention by using trend analysis and linear fitting. The results show that mobile users are the main focus of network attention; Changsha Weather network attention is significantly correlated with the lowest temperature, relative humidity, wind speed, sunshine hours, and precipitation; the probability and frequency of news headlines in the weather of drastical cooling, continuous rainstorm process, lightning warning and so on are large; and the network attention of the whole Changsha tourism is significantly correlated with average temperature, maximum temperature, minimum temperature, wind speed and relative humidity; the network attention of rural tourism is significantly correlated with temperature and precipitation; the network attention of Changsha weather, the whole Changsha tourism is on the rise, but the network attention Changsha rural tourism is on the decline; Changsha Weather Network attention is on the decline; Changsha Weather Network attention is on the rise. Local users account for 66.4%, followed by Beijing, Guangzhou, Shenzhen and Chengdu. The number of tourists is obviously affected by average temperature, average maximum temperature, average minimum temperature and sunshine hours.
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.