ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 47,Issue 9,2021 Table of Contents
MA Zhanshan
,
LIU Qijun
,
SUN Jian
,
KONG Qi
,
LI Zhe
,
SHEN Xueshun
,
ZHAO Chuanfeng
,
DAI Kan
,
TAO Fa
2021, 47(9):1029-1046.
DOI: 10.7519/j.issn.1000-0526.2021.09.001
Abstract:
The GRAPES regional operational model in the National Meteorological Centre significantly overestimated the snowfall amount over North China that occurred in 29-30 November 2019. In this paper, the simulated results from the operational WSM6 cloud microphysics scheme are compared with those from Liu-Ma scheme and the ERA5 reanalysis data to investigate the possible reasons. The results show that during this snowfall, the sedimentations of ice crystals and snow were the main contribution in WSM6 scheme, while the precipitation of Liu-Ma scheme was mainly through the sedimentations of snow and graupel, and ice crystals produced less precipitation. The WSM6 scheme evidently underestimated the liquid water content in the atmosphere and the ice crystal content was the largest composition of the ice-phase particles, followed by the snow content. These features were significantly different from the ERA5 data and the Liu-Ma scheme, and the latter two were in good agreement. Compared with the Liu-Ma scheme, the WSM6 scheme had a higher ice crystal content in the lower layer of the model and a larger average ice crystal falling speed, and their combination made ice crystal precipitation become an important contribution to the formation of this snowfall case. The average snow falling speed in the WSM6 scheme was greater than that of Liu-Ma scheme, which was the main reason why the column snow content was small and the precipitation of snow was more than that of the Liu-Ma scheme. In the WSM6 scheme, the deposition/sublimation process of ice crystals dominated the ice-phase microphysical processes so that the sublimation processes of snow and graupel and the condensation process of cloud water were obviously insufficient. This was the main reason for more ice crystals, less snow and cloud water in WSM6 scheme. The sensitivity test for the ice crystal deposition/sublimation process (SVI) revealed that the SVI conversion rate was positively correlated to surface precipitation, and took on a “seesaw” relationship with the column cloud water content. When the SVI conversion rate was reduced, the ground snowfall tended to be significantly reduced and the column cloud water content increased significantly.
The GRAPES regional operational model in the National Meteorological Centre significantly overestimated the snowfall amount over North China that occurred in 29-30 November 2019. In this paper, the simulated results from the operational WSM6 cloud microphysics scheme are compared with those from Liu-Ma scheme and the ERA5 reanalysis data to investigate the possible reasons. The results show that during this snowfall, the sedimentations of ice crystals and snow were the main contribution in WSM6 scheme, while the precipitation of Liu-Ma scheme was mainly through the sedimentations of snow and graupel, and ice crystals produced less precipitation. The WSM6 scheme evidently underestimated the liquid water content in the atmosphere and the ice crystal content was the largest composition of the ice-phase particles, followed by the snow content. These features were significantly different from the ERA5 data and the Liu-Ma scheme, and the latter two were in good agreement. Compared with the Liu-Ma scheme, the WSM6 scheme had a higher ice crystal content in the lower layer of the model and a larger average ice crystal falling speed, and their combination made ice crystal precipitation become an important contribution to the formation of this snowfall case. The average snow falling speed in the WSM6 scheme was greater than that of Liu-Ma scheme, which was the main reason why the column snow content was small and the precipitation of snow was more than that of the Liu-Ma scheme. In the WSM6 scheme, the deposition/sublimation process of ice crystals dominated the ice-phase microphysical processes so that the sublimation processes of snow and graupel and the condensation process of cloud water were obviously insufficient. This was the main reason for more ice crystals, less snow and cloud water in WSM6 scheme. The sensitivity test for the ice crystal deposition/sublimation process (SVI) revealed that the SVI conversion rate was positively correlated to surface precipitation, and took on a “seesaw” relationship with the column cloud water content. When the SVI conversion rate was reduced, the ground snowfall tended to be significantly reduced and the column cloud water content increased significantly.
2021, 47(9):1047-1061.
DOI: 10.7519/j.issn.1000-0526.2021.09.002
Abstract:
Based on the GRAPES_3 km model developed independently by China and calculating the hourly maximum updraft helicity (UH), we have developed the probabilistic forecast technology which exceeds a certain threshold of UH in different forecast time periods. Since the value of UH can represent the ascending motion and rotation intensity of convective storm, the UH probabilistic forecast product can be used as the probabilistic forecast guidance which characterizes severe convective wind and hail. We verified the probabilistic forecast products of daily tests and typical cases in North China, Northeast China and South China from 14 June to 31 July 2019, the results show that it has a good forecast performance. Compared to the subjective forecast, the threat score (TS) of the objective product for severe convective wind and hail is greatly increased in North China, Northeast China and South China, respectively. Especially for the weak large-scale forcing process in South China, the product can significantly reduce the missing alarm rate (MAR) and significantly increase the TS. In addition, the product can predict the shape distribution and moving propagation characteristics of convective storm, and the region of probabilistic forecast is similar to the observation of severe convective wind and hail. We verified the probabilistic forecast products with different UH thresholds and spatial Gaussian smoothing parameters, the results show that the TS of the products calculated by lower UH threshold is higher than that of higher threshold due to lower MAR. The products with Gaussian smoothing parameter of 20 km have the best forecast performance.
Based on the GRAPES_3 km model developed independently by China and calculating the hourly maximum updraft helicity (UH), we have developed the probabilistic forecast technology which exceeds a certain threshold of UH in different forecast time periods. Since the value of UH can represent the ascending motion and rotation intensity of convective storm, the UH probabilistic forecast product can be used as the probabilistic forecast guidance which characterizes severe convective wind and hail. We verified the probabilistic forecast products of daily tests and typical cases in North China, Northeast China and South China from 14 June to 31 July 2019, the results show that it has a good forecast performance. Compared to the subjective forecast, the threat score (TS) of the objective product for severe convective wind and hail is greatly increased in North China, Northeast China and South China, respectively. Especially for the weak large-scale forcing process in South China, the product can significantly reduce the missing alarm rate (MAR) and significantly increase the TS. In addition, the product can predict the shape distribution and moving propagation characteristics of convective storm, and the region of probabilistic forecast is similar to the observation of severe convective wind and hail. We verified the probabilistic forecast products with different UH thresholds and spatial Gaussian smoothing parameters, the results show that the TS of the products calculated by lower UH threshold is higher than that of higher threshold due to lower MAR. The products with Gaussian smoothing parameter of 20 km have the best forecast performance.
2021, 47(9):1062-1072.
DOI: 10.7519/j.issn.1000-0526.2021.09.003
Abstract:
Based on the data of microwave radiometer, automatic station and Zhangjiakou Radiosonde from 22 January to 30 March 2019 in the Genting Venue of Winter Olympic Games, the accuracy of retrieved temperature and humidity profile was analyzed, and the characteristics and causes of night heat and water vapor were discussed in combination with the 6 h reanalysis data of NCEP/NCAR. The results show that the temperature and water vapor density retrieved by microwave radiometer have a good correlation with the observations by radiosonde and automatic stations, but that of the relative humidity is slightly poor. The mean error (ME) of temperature retrieved by microwave radiometer is relatively small at all levels, and the availability is strong; the root mean squared error of water vapor density are relatively large near the ground, and decrease with the increase of height; the ME of relative humidity at all levels is large, and the maximum reaches 25%. In addition, cloud and precipitation cause the error of temperature and water vapor density to increase at most heights, but the error of relative humidity with precipitation, at most altitudes, is obviously smaller than that under conditons of clear sky and cloud. Further study on the characteristics of heat and water vapor at night shows that the inversion layer structure at night is very common in the Genting Venue, with a probability of 50%. The inversion layer top is generally near or below the mountain top. When combined with warm advection, the thickness and temperature difference of inversion layer will be greatly enhanced. The warm advection and the subsidence movement in the middle and lower layers behind the cold front may bring obvious night temperature increasing to the venue. In the process of temperature increasing dominated by subsidence movement, the profile of microwave radiometer shows that the temperature in the middle and lower layers increases as a whole, and the water vapor density in the lower layers decreases obviously under the effect of subsidence and divergence. In the warming process dominated by warm advection, the warming intensity decreases with height, and the warming process shows obvious humidification phenomenon.
Based on the data of microwave radiometer, automatic station and Zhangjiakou Radiosonde from 22 January to 30 March 2019 in the Genting Venue of Winter Olympic Games, the accuracy of retrieved temperature and humidity profile was analyzed, and the characteristics and causes of night heat and water vapor were discussed in combination with the 6 h reanalysis data of NCEP/NCAR. The results show that the temperature and water vapor density retrieved by microwave radiometer have a good correlation with the observations by radiosonde and automatic stations, but that of the relative humidity is slightly poor. The mean error (ME) of temperature retrieved by microwave radiometer is relatively small at all levels, and the availability is strong; the root mean squared error of water vapor density are relatively large near the ground, and decrease with the increase of height; the ME of relative humidity at all levels is large, and the maximum reaches 25%. In addition, cloud and precipitation cause the error of temperature and water vapor density to increase at most heights, but the error of relative humidity with precipitation, at most altitudes, is obviously smaller than that under conditons of clear sky and cloud. Further study on the characteristics of heat and water vapor at night shows that the inversion layer structure at night is very common in the Genting Venue, with a probability of 50%. The inversion layer top is generally near or below the mountain top. When combined with warm advection, the thickness and temperature difference of inversion layer will be greatly enhanced. The warm advection and the subsidence movement in the middle and lower layers behind the cold front may bring obvious night temperature increasing to the venue. In the process of temperature increasing dominated by subsidence movement, the profile of microwave radiometer shows that the temperature in the middle and lower layers increases as a whole, and the water vapor density in the lower layers decreases obviously under the effect of subsidence and divergence. In the warming process dominated by warm advection, the warming intensity decreases with height, and the warming process shows obvious humidification phenomenon.
2021, 47(9):1073-1085.
DOI: 10.7519/j.issn.1000-0526.2021.09.004
Abstract:
Based on conventional weather data, FY-2F satellite data, Doppler radar products, densely-observed data from automatic surface weather observation system and ERA-Interim 0.125°×0.125° reanalysis data, the ambient condition and evolution of the short-time extreme precipitation event in Chongqing on 19 April 2019 is analyzed. The results show that under weak synoptic-scale vertical motion, this severe rain process was formed by a quasi-stationary meso-β scale convective system (MβCS) over Qijiang River Valley and its vicinity. Before the development of the severe convection, the local water vapor was sufficient, and stratification instability which was established and maintained by the wetter low-level and the drier mid-high-level was prominent. With the terrain inclining from southwest to northeast, Qijiang River Valley, located in the transition zone from Yungui Plateau to Sichuan Basin, was surrounded by mountains on three sides. Flowing from the south side of the valley, the increasing meso-γ scale convective cell brought about heavy rainfall and cold pool in the river valley. The strong mesoscale temperature gradient between the cold pool and the eastern slope of the valley promoted the intense convergence of the near-surface southwest wind to the eastern hillside, which was advantageous to the eastward convergence of the convective cell and strengthening, then the convection was organized into an isolated MβCS. With the coaction of continuous enhancement of the cold pool, topography blocking effect, merging of two MγCSs and weak ambient flow, the MβCS moved slowly, finally resulting in the localized extreme short-time rainfall over Qijiang and Wansheng.
Based on conventional weather data, FY-2F satellite data, Doppler radar products, densely-observed data from automatic surface weather observation system and ERA-Interim 0.125°×0.125° reanalysis data, the ambient condition and evolution of the short-time extreme precipitation event in Chongqing on 19 April 2019 is analyzed. The results show that under weak synoptic-scale vertical motion, this severe rain process was formed by a quasi-stationary meso-β scale convective system (MβCS) over Qijiang River Valley and its vicinity. Before the development of the severe convection, the local water vapor was sufficient, and stratification instability which was established and maintained by the wetter low-level and the drier mid-high-level was prominent. With the terrain inclining from southwest to northeast, Qijiang River Valley, located in the transition zone from Yungui Plateau to Sichuan Basin, was surrounded by mountains on three sides. Flowing from the south side of the valley, the increasing meso-γ scale convective cell brought about heavy rainfall and cold pool in the river valley. The strong mesoscale temperature gradient between the cold pool and the eastern slope of the valley promoted the intense convergence of the near-surface southwest wind to the eastern hillside, which was advantageous to the eastward convergence of the convective cell and strengthening, then the convection was organized into an isolated MβCS. With the coaction of continuous enhancement of the cold pool, topography blocking effect, merging of two MγCSs and weak ambient flow, the MβCS moved slowly, finally resulting in the localized extreme short-time rainfall over Qijiang and Wansheng.
2021, 47(9):1086-1098.
DOI: 10.7519/j.issn.1000-0526.2021.09.005
Abstract:
The radar data of Haikou dual polarization Doppler during the tornado processes in Tunchang County and Danzhou City of Hainan on 29 August 2019 are analyzed. The tornadoes occurred in a convective storm in the typhoon rain belt about 370 km to the right of Typhoon Podul. Both tornado occurrences were related to the mergering of the storms. One occurred at 12 min before the mergering of the storm cells, and another occurred at 5 min after the storm cells merged. The merger of the cell led to enhancement of the storm reflectivity with the storm height increasing, and the cyclone in the storm strengthened rapidly. Tornadic vortex signature (TVS) was detected during two tornadoes, and the time of detection of TVS was 27 min and 5 min earlier than the time of the tornadoes. Corresponding to the position of the TVS before the tornado occurred, the correlation coefficient (CC) value did not change. When the tornado occurred, the CC value of the position of the TVS suddenly decreased to below 0.8, and the low-value of the CC continued for more than 20 min after the tornado occurred. Both tornadoes had the rear storm cells merged. The tornado occurred at the rear of the main storm cells at the junction where the two storm cells merged.
The radar data of Haikou dual polarization Doppler during the tornado processes in Tunchang County and Danzhou City of Hainan on 29 August 2019 are analyzed. The tornadoes occurred in a convective storm in the typhoon rain belt about 370 km to the right of Typhoon Podul. Both tornado occurrences were related to the mergering of the storms. One occurred at 12 min before the mergering of the storm cells, and another occurred at 5 min after the storm cells merged. The merger of the cell led to enhancement of the storm reflectivity with the storm height increasing, and the cyclone in the storm strengthened rapidly. Tornadic vortex signature (TVS) was detected during two tornadoes, and the time of detection of TVS was 27 min and 5 min earlier than the time of the tornadoes. Corresponding to the position of the TVS before the tornado occurred, the correlation coefficient (CC) value did not change. When the tornado occurred, the CC value of the position of the TVS suddenly decreased to below 0.8, and the low-value of the CC continued for more than 20 min after the tornado occurred. Both tornadoes had the rear storm cells merged. The tornado occurred at the rear of the main storm cells at the junction where the two storm cells merged.
2021, 47(9):1099-1112.
DOI: 10.7519/j.issn.1000-0526.2021.09.006
Abstract:
Compared with the situation on clear days, the vertical distribution of aerosol and meteorological conditions during haze and heavy haze events in central part of Shandong Province from 2007 to 2017 are analyzed by utilizing the data of CALIPSO (The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) and NCEP FNL （Final Operational Global Analysis） 1°×1° reanalysis data. The results show that aerosol particles in haze and heavy haze weather mainly concentrate below 2.7 km and 1.5 km in the lower troposphere. With 0.9, 1.66 and 1.34 km as the critical heights, the extinction coefficient (EC) of clear days, haze days and heavy haze days decreases exponentially above the critical height and logarithmically below the height. The average annual paraticulate deploarization ratio (PDR) and color ratio (CR) range of haze days and severe haze days are 0.1-0.3 and 0.5-0.9, respectively. In heavy haze days, aerosol particles below 2 km are relatively regular and small in size, and their irregularity and size increase sharply within 2-4 km. PDR increases gradually with height in and below 7 km but decreases gradually above 7 km. Different from clear days, CR basically increases with the height on haze days. The contribution of polluted dust aerosol to near-ground EC on heavy haze days and haze days is 0.58 km-1 and 0.36 km-1, respectively. The second is 〖JP2〗the polluted continental type, contributing 0.27 km-1 and 0.20 km-1〖JP〗 respectively. On the heavy haze days, the low average wind speed and high relative humidity in and below 1.5 km are conducive to the increase of EC. On haze days, low average wind speed and high relative humidity are maintained at a higher height, making the height of aerosol high concentration layer up to 2.7 km. During haze days, the sources of near-surface pollutants are long-distance transmission from Mongolia, Inner Mongolia and the neighboring provinces. In heavy haze days, the transport of pollutants in the direction of Mongolia and Henan accounts for more, reaching to 25.26% and 31.58% respectively. The proportion of multi-layer inversion corresponding to heavy haze is close to 50%, and the proportion of ground+low-suspended type and ground+high-suspended type are the largest. Since these two types of inversion correspond to smaller outflow below the inversion layer, the atmosphere is more stable,and aerosol particles are concentrated in the lower layer when it is heavy haze weather.
Compared with the situation on clear days, the vertical distribution of aerosol and meteorological conditions during haze and heavy haze events in central part of Shandong Province from 2007 to 2017 are analyzed by utilizing the data of CALIPSO (The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) and NCEP FNL （Final Operational Global Analysis） 1°×1° reanalysis data. The results show that aerosol particles in haze and heavy haze weather mainly concentrate below 2.7 km and 1.5 km in the lower troposphere. With 0.9, 1.66 and 1.34 km as the critical heights, the extinction coefficient (EC) of clear days, haze days and heavy haze days decreases exponentially above the critical height and logarithmically below the height. The average annual paraticulate deploarization ratio (PDR) and color ratio (CR) range of haze days and severe haze days are 0.1-0.3 and 0.5-0.9, respectively. In heavy haze days, aerosol particles below 2 km are relatively regular and small in size, and their irregularity and size increase sharply within 2-4 km. PDR increases gradually with height in and below 7 km but decreases gradually above 7 km. Different from clear days, CR basically increases with the height on haze days. The contribution of polluted dust aerosol to near-ground EC on heavy haze days and haze days is 0.58 km-1 and 0.36 km-1, respectively. The second is 〖JP2〗the polluted continental type, contributing 0.27 km-1 and 0.20 km-1〖JP〗 respectively. On the heavy haze days, the low average wind speed and high relative humidity in and below 1.5 km are conducive to the increase of EC. On haze days, low average wind speed and high relative humidity are maintained at a higher height, making the height of aerosol high concentration layer up to 2.7 km. During haze days, the sources of near-surface pollutants are long-distance transmission from Mongolia, Inner Mongolia and the neighboring provinces. In heavy haze days, the transport of pollutants in the direction of Mongolia and Henan accounts for more, reaching to 25.26% and 31.58% respectively. The proportion of multi-layer inversion corresponding to heavy haze is close to 50%, and the proportion of ground+low-suspended type and ground+high-suspended type are the largest. Since these two types of inversion correspond to smaller outflow below the inversion layer, the atmosphere is more stable,and aerosol particles are concentrated in the lower layer when it is heavy haze weather.
2021, 47(9):1113-1121.
DOI: 10.7519/j.issn.1000-0526.2021.09.007
Abstract:
Using the methods of element consistency, internal consistency and spatial consistency, the data qualities of 81 national surface meteorological stations in Anhui Province from 1961 to 2018 are controlled. The Bayes discriminant model is trained based on the normal year data after quality control, and the icing data of abnormal year are corrected by the model. The results show that total 84 years’ annual icing days from 38 stations in Anhui Province are abnormal, mainly concentrated in 1961-1970, 1988-1999 and 2015-2017, and fail to pass the quality control. The main reasons for these phenomena are the simplification of historical observation tasks of some stations, the adjustment of meteorological station classification, the reform of ground meteorological observation operation and so on. Then, by using the Bayes discriminant method, several discrimination models of icing weather phenomena are constructed. After verification, it is found that Model 1 and Model 3 have higher recognition accuracy, hit rate and TS score but lower false alarm rate. Considering the simplicity of calculation, Model 1 is selected to correct the icing data of abnormal years day by day. In addition, through the comparison of the icing weather phenomena correction results of Lu’an, Taihe and Wuwei Stations in abnormal years, we find that the model based on Bayes discriminant method is more reasonable for the correction of the icing weather phenomena caused by different reasons in different time periods, and the variation trend of annual icing days after correction is more in line with the actual situation, which shows that the Bayes discrimination model is reasonable and feasible to correct the icing weather phenomena.
Using the methods of element consistency, internal consistency and spatial consistency, the data qualities of 81 national surface meteorological stations in Anhui Province from 1961 to 2018 are controlled. The Bayes discriminant model is trained based on the normal year data after quality control, and the icing data of abnormal year are corrected by the model. The results show that total 84 years’ annual icing days from 38 stations in Anhui Province are abnormal, mainly concentrated in 1961-1970, 1988-1999 and 2015-2017, and fail to pass the quality control. The main reasons for these phenomena are the simplification of historical observation tasks of some stations, the adjustment of meteorological station classification, the reform of ground meteorological observation operation and so on. Then, by using the Bayes discriminant method, several discrimination models of icing weather phenomena are constructed. After verification, it is found that Model 1 and Model 3 have higher recognition accuracy, hit rate and TS score but lower false alarm rate. Considering the simplicity of calculation, Model 1 is selected to correct the icing data of abnormal years day by day. In addition, through the comparison of the icing weather phenomena correction results of Lu’an, Taihe and Wuwei Stations in abnormal years, we find that the model based on Bayes discriminant method is more reasonable for the correction of the icing weather phenomena caused by different reasons in different time periods, and the variation trend of annual icing days after correction is more in line with the actual situation, which shows that the Bayes discrimination model is reasonable and feasible to correct the icing weather phenomena.
2021, 47(9):1122-1134.
DOI: 10.7519/j.issn.1000-0526.2021.09.008
Abstract:
Based on the improved stratification analysis method, the freezing rain fall zones and the altitudes of five severe freezing rain processes that occurred in China during 2008-2019 are calculated, and the result is verified by using the glaze data observed at 2 〖KG-*5〗000 stations and the ice disaster data of power grid. The calculated freezing rain fall zones cover both the areas with glaze and the areas with severe freezing rain disaster. The calculated altitudes of freezing rain occurrence are also consistent with the altitudes of ice disasters. The calculated results can well explain the phenomenon that there is freezing rain disaster but no glaze records under complex terrain conditions. The five calculated freezing rain fall zones are superimposed, showing that there is a freezing rain belt from Guizhou, Hunan, Jiangxi to Zhejiang, with the day number of freezing rain from high to low. The freezing rain belt can develop northward to Sichuan, Chongqing, Hubei and southern Anhui， and southward to Yunnan, Guangxi, Guangdong and northern Fujian. There is a typical cold-warm-cold stratification above the freezing rain zone. However, there is a warm-cold-warm-cold stratification above the freezing rain zone in greatly undulate terrain, such as Zhejiang and the north of Guangxi, Guangdong and Fujian, that is, there is a shallow warm layer with temperature higher than 0℃ near the surface. Therefore, the freezing rain usually occurs in the mountainous areas with an altitude above 300-400 m in Zhejiang and northern Fujian. The northeast of Guangxi and the northwest of Guangdong are also affected by the deep warm layer, and the freezing rain mostly occurs in the hillside areas with an altitude of 300-1 〖KG-*5〗300 m.
Based on the improved stratification analysis method, the freezing rain fall zones and the altitudes of five severe freezing rain processes that occurred in China during 2008-2019 are calculated, and the result is verified by using the glaze data observed at 2 〖KG-*5〗000 stations and the ice disaster data of power grid. The calculated freezing rain fall zones cover both the areas with glaze and the areas with severe freezing rain disaster. The calculated altitudes of freezing rain occurrence are also consistent with the altitudes of ice disasters. The calculated results can well explain the phenomenon that there is freezing rain disaster but no glaze records under complex terrain conditions. The five calculated freezing rain fall zones are superimposed, showing that there is a freezing rain belt from Guizhou, Hunan, Jiangxi to Zhejiang, with the day number of freezing rain from high to low. The freezing rain belt can develop northward to Sichuan, Chongqing, Hubei and southern Anhui， and southward to Yunnan, Guangxi, Guangdong and northern Fujian. There is a typical cold-warm-cold stratification above the freezing rain zone. However, there is a warm-cold-warm-cold stratification above the freezing rain zone in greatly undulate terrain, such as Zhejiang and the north of Guangxi, Guangdong and Fujian, that is, there is a shallow warm layer with temperature higher than 0℃ near the surface. Therefore, the freezing rain usually occurs in the mountainous areas with an altitude above 300-400 m in Zhejiang and northern Fujian. The northeast of Guangxi and the northwest of Guangdong are also affected by the deep warm layer, and the freezing rain mostly occurs in the hillside areas with an altitude of 300-1 〖KG-*5〗300 m.
2021, 47(9):1135-1145.
DOI: 10.7519/j.issn.1000-0526.2021.09.009
Abstract:
In this paper, the GPS-PWV (GPS/PWV) of GPS inversion of 11 stations in the central and eastern Qilian Mountains from 2016 to 2018 is used to analyze the characteristics of the spatio-temporal distribution, zonality and vertical charge of precipitable water vapor. The results show that compared to the PWV calculated from sounding data from Zhangye and Minqin stations, the average root-mean-square error and deviation are 2.1 mm and 1.07 mm respectively. GPS/PWV is slightly larger than RS/PWV, and the correlation coefficient of the two results reaches 〖JP2〗0.97. The PWV in the central and eastern Qilian Mountains has characteristics of obvious daily, monthly and seasonal variations. The daily maximum of PWV appears between 11:00-16:00 BT and the minimum between 01:00-05:00 BT. The monthly maximum occurs in August, and the monthly minimum is in January-February. The PWV seasonal variation shows a decreasing order from summer to autumn, spring and winter. The areas with high PWV values are mainly located in the southern part of Qilian Mountains, with obvious low-value areas at Gangcha and Minhe stations in the middle section of Qilian Mountains. PWV has obvious characteristics of zonatity and vertical change. The correlation coefficient between PWV and altitude reaches -0.77. PWV increases gradually from west to east with longitude, showing a change of high-low-high trend from south to north. In addition, the spatial distribution and seasonal change of PWV are also related to the effect of monsoon.
In this paper, the GPS-PWV (GPS/PWV) of GPS inversion of 11 stations in the central and eastern Qilian Mountains from 2016 to 2018 is used to analyze the characteristics of the spatio-temporal distribution, zonality and vertical charge of precipitable water vapor. The results show that compared to the PWV calculated from sounding data from Zhangye and Minqin stations, the average root-mean-square error and deviation are 2.1 mm and 1.07 mm respectively. GPS/PWV is slightly larger than RS/PWV, and the correlation coefficient of the two results reaches 〖JP2〗0.97. The PWV in the central and eastern Qilian Mountains has characteristics of obvious daily, monthly and seasonal variations. The daily maximum of PWV appears between 11:00-16:00 BT and the minimum between 01:00-05:00 BT. The monthly maximum occurs in August, and the monthly minimum is in January-February. The PWV seasonal variation shows a decreasing order from summer to autumn, spring and winter. The areas with high PWV values are mainly located in the southern part of Qilian Mountains, with obvious low-value areas at Gangcha and Minhe stations in the middle section of Qilian Mountains. PWV has obvious characteristics of zonatity and vertical change. The correlation coefficient between PWV and altitude reaches -0.77. PWV increases gradually from west to east with longitude, showing a change of high-low-high trend from south to north. In addition, the spatial distribution and seasonal change of PWV are also related to the effect of monsoon.
10 Construction of Integrated Meteorological Forecast Service Platform Based on MICAPS4 Web Framework
2021, 47(9):1146-1155.
DOI: 10.7519/j.issn.1000-0526.2021.09.010
Abstract:
The Hubei Meteorological Forecast Service Integration Platform is designed and developed based on the MICAPS4 Web Platform developed by National Meteorological Centre, which can effectively connect China Integrated Meteorological Information Sharing System (CIMISS) and the distributed database of Meteorology Information Comprehensive Analysis Process System version 4 （MICAPS4）. The platform integrates guidance and warning of primary focus, sharing and enquiry of real-time monitoring, comparative analysis of climate characteristics, comprehensive analysis of weather forecast, associative retrieval of service products, product generation and one-click distribution, application of professional service and management of information data system. The platform adopts key technologies including intensive application of meteorological big data, rule matching of work guidance, customized synthesis of automatic product generation and collaborative linkage of service response feedback. The platform has helped to realize the stable application in the three-level meteorological departments of the cities and counties in Hubei Province. The application results show that the integrated platform has greatly improved the level of business intensification and service collaboration of meteorological forecast service in provinces, cities and counties, promoting the establishment of the specifications of various operational processes including information transmission, product manufacture, service distribution and linkage response. The successful practice of applying MICAPS4 web framework to the establishment of the integrated platform of meteorological forecast service in Hubei Province has provided an effective alternative for the domestic provincial meteorological departments to follow the state-level technological development in time and carry out the construction of meteorological operation system under the big data application scenario.
The Hubei Meteorological Forecast Service Integration Platform is designed and developed based on the MICAPS4 Web Platform developed by National Meteorological Centre, which can effectively connect China Integrated Meteorological Information Sharing System (CIMISS) and the distributed database of Meteorology Information Comprehensive Analysis Process System version 4 （MICAPS4）. The platform integrates guidance and warning of primary focus, sharing and enquiry of real-time monitoring, comparative analysis of climate characteristics, comprehensive analysis of weather forecast, associative retrieval of service products, product generation and one-click distribution, application of professional service and management of information data system. The platform adopts key technologies including intensive application of meteorological big data, rule matching of work guidance, customized synthesis of automatic product generation and collaborative linkage of service response feedback. The platform has helped to realize the stable application in the three-level meteorological departments of the cities and counties in Hubei Province. The application results show that the integrated platform has greatly improved the level of business intensification and service collaboration of meteorological forecast service in provinces, cities and counties, promoting the establishment of the specifications of various operational processes including information transmission, product manufacture, service distribution and linkage response. The successful practice of applying MICAPS4 web framework to the establishment of the integrated platform of meteorological forecast service in Hubei Province has provided an effective alternative for the domestic provincial meteorological departments to follow the state-level technological development in time and carry out the construction of meteorological operation system under the big data application scenario.
2021, 47(9):1156-1161.
DOI: 10.7519/j.issn.1000-0526.2021.09.011
Abstract:
The vorticity and divergence are two basic and important diagnostic physical quantities for the evolution process of the synoptic systems and phenomena in the common meteorological coordinate systems. In this paper, the formula between the vorticity in the isobaric coordinates (“p” coordinate) and one in the local rectangular coordinates (“z” coordinate) is obtained via coordinate transformation method. So done for the divergence. The results show that the expression forms of the vorticity and the divergence are exactly same in both coordinates, but they have essential differences. The vorticity in the “p” coordinate not only indicates the rotation of the air parcel around the vertical axis, but also implies the atmospheric baroclinity. Similarly, the divergence in the “p” coordinate not only expresses the relative variable ratio of the horizontal area of the air parcel, but also indicates the atmospheric baroclinity. In the area of the front, the difference of the vorticity is very obvious in “p” coordinate and “z” coordinate, and the same difference is found for the divergence. If the atmosphere is barotropic, the vorticity in the “p” coordinate equals that in the “z” coordinate. The same is true for the divergence. The vorticity and divergence both have the dynamic and thermodynamic natures of the atmosphere in the “p” coordinate.
The vorticity and divergence are two basic and important diagnostic physical quantities for the evolution process of the synoptic systems and phenomena in the common meteorological coordinate systems. In this paper, the formula between the vorticity in the isobaric coordinates (“p” coordinate) and one in the local rectangular coordinates (“z” coordinate) is obtained via coordinate transformation method. So done for the divergence. The results show that the expression forms of the vorticity and the divergence are exactly same in both coordinates, but they have essential differences. The vorticity in the “p” coordinate not only indicates the rotation of the air parcel around the vertical axis, but also implies the atmospheric baroclinity. Similarly, the divergence in the “p” coordinate not only expresses the relative variable ratio of the horizontal area of the air parcel, but also indicates the atmospheric baroclinity. In the area of the front, the difference of the vorticity is very obvious in “p” coordinate and “z” coordinate, and the same difference is found for the divergence. If the atmosphere is barotropic, the vorticity in the “p” coordinate equals that in the “z” coordinate. The same is true for the divergence. The vorticity and divergence both have the dynamic and thermodynamic natures of the atmosphere in the “p” coordinate.
2021, 47(9):1162-1168.
DOI: 10.7519/j.issn.1000-0526.2021.09.012
Abstract:
The main characteristics of the general atmospheric circulation in June 2021 are as follows. There was one polar vortex center with stronger strength than normal in the Northern Hemisphere. The 500 hPa geopotential height over Europe was stronger than normal. The western Pacific subtropical high moved northward during middle dekads of this month and then southward in the last dekad. In June, the monthly mean precipitation of China was 91.5 mm, which was less than the normal by 8%. The negative precipitation anomaly reached 20%-50% in most part of Jiangnan, north part of South China and Jianghuai Region. In some regions the negative anomaly exceeded 50%. However, the positive precipitation anomaly reached more than 50% in northern Inner Mongolia, western Heilongjiang Province and eastern Jilin Province as well as central and eastern Liaoning Province. The monthly mean temperature of China was 20.8℃, which was a little higher than the usual. However, it was even 2℃ warmer than the normal in northern Henan Province, central Jiangsu Province and southern Qinghai Province. In June, eight regional torrential rain processes which mostly occurred in South China, and the observed values at many stations reached the standard of extreme precipitation events. Two typhoons were generated and neither of them landed in China in June. There were 44 stations where extreme high temperature events occurred and these stations are mostly located in the regions of Huanghuai, Jianghuai and South China. In addition, the daily maximum temperature at four stations broke the historical record.
The main characteristics of the general atmospheric circulation in June 2021 are as follows. There was one polar vortex center with stronger strength than normal in the Northern Hemisphere. The 500 hPa geopotential height over Europe was stronger than normal. The western Pacific subtropical high moved northward during middle dekads of this month and then southward in the last dekad. In June, the monthly mean precipitation of China was 91.5 mm, which was less than the normal by 8%. The negative precipitation anomaly reached 20%-50% in most part of Jiangnan, north part of South China and Jianghuai Region. In some regions the negative anomaly exceeded 50%. However, the positive precipitation anomaly reached more than 50% in northern Inner Mongolia, western Heilongjiang Province and eastern Jilin Province as well as central and eastern Liaoning Province. The monthly mean temperature of China was 20.8℃, which was a little higher than the usual. However, it was even 2℃ warmer than the normal in northern Henan Province, central Jiangsu Province and southern Qinghai Province. In June, eight regional torrential rain processes which mostly occurred in South China, and the observed values at many stations reached the standard of extreme precipitation events. Two typhoons were generated and neither of them landed in China in June. There were 44 stations where extreme high temperature events occurred and these stations are mostly located in the regions of Huanghuai, Jianghuai and South China. In addition, the daily maximum temperature at four stations broke the historical record.
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ISSN:1000-0526 CN:11-2282/P