ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 48,Issue 8,2022 Table of Contents
2022, 48(8):945-962.
DOI: 10.7519/j.issn.1000-0526.2022.012701
Abstract:
How to evaluate the cloud seeding effect is a key issue of weather modification activities. This paper summarizes the quantitative evaluation studies of artificial precipitation enhancement in China in recent years. The concept, approach, impact factors, and disadvantages of quantitative evaluation are systematically introduced. The increment rate in every literature is studied intensively to give a brief review on the quantitative evaluation of weather modification operations carried out in China. Moreover, some aspects for development and improvement of evaluation technology are discussed in detail to provide help and advice for future cloud seeding evaluation studies.
How to evaluate the cloud seeding effect is a key issue of weather modification activities. This paper summarizes the quantitative evaluation studies of artificial precipitation enhancement in China in recent years. The concept, approach, impact factors, and disadvantages of quantitative evaluation are systematically introduced. The increment rate in every literature is studied intensively to give a brief review on the quantitative evaluation of weather modification operations carried out in China. Moreover, some aspects for development and improvement of evaluation technology are discussed in detail to provide help and advice for future cloud seeding evaluation studies.
2022, 48(8):963-978.
DOI: 10.7519/j.issn.1000-0526.2022.041001
Abstract:
Using the 10 min surface rainfall observations in Anhui Province during the 2011-2018 warm seasons (May to August), the spatio-temporal distributions of hourly heavy rainfall (HHR) events during the pre-Meiyu, Meiyu, and post-Meiyu periods are comparatively analyzed. The results show that the HHR events frequently occur over the areas from Dabie Mountains (Mt.DB) to the southwest of the southern Anhui Mountains (Mt.WN). The contribution of the HHR events over the southwest and northeast of Anhui Province to the total precipitation during the warm-season reaches 30%-40%. During the pre-Meiyu period, the HHR events have a lower occurrence frequency and weaker rainfall intensity than in the Meiyu and post-Meiyu periods. The HHR events during the Meiyu period last longer and produce a larger rainfall accumulation than those during the pre- and post-Meiyu periods, while those during the post-Meiyu period have larger intensity but shorter duration. Defined according to the 99th percentile threshold, more than 60% of the extreme persistent (accumulated rainfall) HHR events take place during the Meiyu period, while more than 60% of the extreme rainfall intensity HHR events with 10 min rainfall ≥25 mm occur during the post-Meiyu period. The HHR events’ occurrence frequency peaks at 06:00 BT and 17:00 BT during the Meiyu period, but exhibits a prominent single peak at 16:00 BT during the post-Meiyu period. Based on the rotating T model of the principal component analysis, the main synoptic circulation patterns of the HHR events can be classified as the southwest vortex/shear type or front type (SP2) and northwest trough type (SP1) during the Meiyu period. The SP2 type HHR events are the major contributor to the HHR accumulation and mainly occur in Mt. DB, Mt. WN and their transition zones. HHR events of the SP1 type tend to occur in mountainous areas such as Mt.DB, Mt.WN and northeastern Anhui. During the post-Meiyu period, the two major patterns are the southern low-pressure or typhoon type (SP6) and northwest low trough type (SP1). The major contributor to the HHR accumulation is the SP6 type HHR events that occur mainly in Mt. DB and Mt. WN, while the SP1 type HHR events take place more in the north than in the south.
Using the 10 min surface rainfall observations in Anhui Province during the 2011-2018 warm seasons (May to August), the spatio-temporal distributions of hourly heavy rainfall (HHR) events during the pre-Meiyu, Meiyu, and post-Meiyu periods are comparatively analyzed. The results show that the HHR events frequently occur over the areas from Dabie Mountains (Mt.DB) to the southwest of the southern Anhui Mountains (Mt.WN). The contribution of the HHR events over the southwest and northeast of Anhui Province to the total precipitation during the warm-season reaches 30%-40%. During the pre-Meiyu period, the HHR events have a lower occurrence frequency and weaker rainfall intensity than in the Meiyu and post-Meiyu periods. The HHR events during the Meiyu period last longer and produce a larger rainfall accumulation than those during the pre- and post-Meiyu periods, while those during the post-Meiyu period have larger intensity but shorter duration. Defined according to the 99th percentile threshold, more than 60% of the extreme persistent (accumulated rainfall) HHR events take place during the Meiyu period, while more than 60% of the extreme rainfall intensity HHR events with 10 min rainfall ≥25 mm occur during the post-Meiyu period. The HHR events’ occurrence frequency peaks at 06:00 BT and 17:00 BT during the Meiyu period, but exhibits a prominent single peak at 16:00 BT during the post-Meiyu period. Based on the rotating T model of the principal component analysis, the main synoptic circulation patterns of the HHR events can be classified as the southwest vortex/shear type or front type (SP2) and northwest trough type (SP1) during the Meiyu period. The SP2 type HHR events are the major contributor to the HHR accumulation and mainly occur in Mt. DB, Mt. WN and their transition zones. HHR events of the SP1 type tend to occur in mountainous areas such as Mt.DB, Mt.WN and northeastern Anhui. During the post-Meiyu period, the two major patterns are the southern low-pressure or typhoon type (SP6) and northwest low trough type (SP1). The major contributor to the HHR accumulation is the SP6 type HHR events that occur mainly in Mt. DB and Mt. WN, while the SP1 type HHR events take place more in the north than in the south.
2022, 48(8):979-992.
DOI: 10.7519/j.issn.1000-0526.2022.051101
Abstract:
Based on the conventional high-altitude and surface observation data, NCEP/NCAR reanalysis data and radar data, this paper analyzes the mechanism and evolution characteristics of convection initiation under the influence of cold air in Suizhou and Jingzhou areas of Hubei Province on 4 May 2020. The results show that there were three initiation processes of severe convection in Suizhou Area, including warm sector convergence process, cold front process and low-level jet process. At the same time, the special topography of Suizhou played an important role in the maintenance of severe convection. The condition of convective initiation under the influence of cold air was related to the thickness of cold air and the level of free convection. When the convergence level of cold air and warm moisture flow was higher than the free convection level and the convergence had a certain vertical thickness, convection initiation was more likely to occur. The cold air intensity in Suizhou was stronger than that in Jingzhou, and the front at lower tropospheric level was strong, the updraft in the middle and east area of the positive potential vorticity anomaly was strong, which favored convection initiation. However, there was no convective initiation in Jingzhou, because the lower tropospheric front was weakened, and the cold air and updraft were also weaker.
Based on the conventional high-altitude and surface observation data, NCEP/NCAR reanalysis data and radar data, this paper analyzes the mechanism and evolution characteristics of convection initiation under the influence of cold air in Suizhou and Jingzhou areas of Hubei Province on 4 May 2020. The results show that there were three initiation processes of severe convection in Suizhou Area, including warm sector convergence process, cold front process and low-level jet process. At the same time, the special topography of Suizhou played an important role in the maintenance of severe convection. The condition of convective initiation under the influence of cold air was related to the thickness of cold air and the level of free convection. When the convergence level of cold air and warm moisture flow was higher than the free convection level and the convergence had a certain vertical thickness, convection initiation was more likely to occur. The cold air intensity in Suizhou was stronger than that in Jingzhou, and the front at lower tropospheric level was strong, the updraft in the middle and east area of the positive potential vorticity anomaly was strong, which favored convection initiation. However, there was no convective initiation in Jingzhou, because the lower tropospheric front was weakened, and the cold air and updraft were also weaker.
2022, 48(8):993-1006.
DOI: 10.7519/j.issn.1000-0526.2022.040901
Abstract:
On 30 July 2015, a warm-sector extreme severe precipitation process broke out in a wide range of Shandong Province, and the prediction deviation was large because the triggering mechanism was not obvious and the forecasters’ judgment of the development direction of the convection system was insufficient. By using multi-source observational data, the triggering mechanism and evolution of convective system organization are analyzed in this paper. The results show that the upper trough and the low-level jet favored the occurrence and development of the deep wet convection. There was sufficient water vapor and favorable thermal condition before the convection. The horizontal convective rolls shown on the cloud and radar images indicated that the potential of convection generation and development was enhanced. The cold air intruded into northern Shandong through Bohai Sea and triggered the original convection, which further strengthened, generating the surface cold pool and the gust front. The gust front continued to trigger convection, forming a backward developing multi-cell storm. At this stage, the low-level environmental wind direction determined the development direction of convective storm. The mechanism for the organization and maintenance of the convective system is as follows: the strengthening of the surface cold pool and the development of convective storms formed a positive feedback, the surface cold pool and low-level environmental vertical wind shear reached a dynamic balance, and the multi-cell storm gradually developed into a linear mesoscale convective system (LMCS). With the gradual enhancement of the deep vertical wind shear, the structure of LMCS became closer.The mechanism of weakening and extinction of convective system is as follows: blocked by the terrain in the middle mountain area of Shandong Province, the main body of the surface cold pool remained in the central part of Shandong Province, the intensity of the gust front in the front of the cold pool decreased rapidly, and the LMCS was divided into east and west segments, then the east and west segments of the LMCS weakened and died out under the unfavorable low-level vertical wind shear. The RKW theory is applicable to explain the evolution of the LMCS organization.
On 30 July 2015, a warm-sector extreme severe precipitation process broke out in a wide range of Shandong Province, and the prediction deviation was large because the triggering mechanism was not obvious and the forecasters’ judgment of the development direction of the convection system was insufficient. By using multi-source observational data, the triggering mechanism and evolution of convective system organization are analyzed in this paper. The results show that the upper trough and the low-level jet favored the occurrence and development of the deep wet convection. There was sufficient water vapor and favorable thermal condition before the convection. The horizontal convective rolls shown on the cloud and radar images indicated that the potential of convection generation and development was enhanced. The cold air intruded into northern Shandong through Bohai Sea and triggered the original convection, which further strengthened, generating the surface cold pool and the gust front. The gust front continued to trigger convection, forming a backward developing multi-cell storm. At this stage, the low-level environmental wind direction determined the development direction of convective storm. The mechanism for the organization and maintenance of the convective system is as follows: the strengthening of the surface cold pool and the development of convective storms formed a positive feedback, the surface cold pool and low-level environmental vertical wind shear reached a dynamic balance, and the multi-cell storm gradually developed into a linear mesoscale convective system (LMCS). With the gradual enhancement of the deep vertical wind shear, the structure of LMCS became closer.The mechanism of weakening and extinction of convective system is as follows: blocked by the terrain in the middle mountain area of Shandong Province, the main body of the surface cold pool remained in the central part of Shandong Province, the intensity of the gust front in the front of the cold pool decreased rapidly, and the LMCS was divided into east and west segments, then the east and west segments of the LMCS weakened and died out under the unfavorable low-level vertical wind shear. The RKW theory is applicable to explain the evolution of the LMCS organization.
2022, 48(8):1007-1019.
DOI: 10.7519/j.issn.1000-0526.2022.052801
Abstract:
By using conventional observation data, automatic meteorological station data and NCEP reanalysis data, as well as the data of CINRAD and meteorological satellite, the mesoscale weather system development models in the boundary layer of extreme rainstorm under three different weather types are summarized, based on the systematic analysis about the dynamic and thermal characteristics of the boundary layer mesoscale weather system in 39 cases of extreme rainstorms. The results show that the mesoscale weather systems in extreme rainstorm share the same regularity under the same weather system. The occurrence of extreme rainstorm is closely related to the strong development of mesoscale weather system in boundary layer. The special topography in the middle reaches of the Yangtze River plays an important role in the occurrence and development of mesoscale weather systems. By the trigger and organization of strong developing mesoscale weather system in boundary layer under the background of favorable circulation, the consolidation strengthening, stagnation, backward propagation of mesoscale convective system (MCS) and convective cell train effect are important reasons for extreme heavy rainfalls. To be specific, there are three paterns of surface mesoscale synoptic systems related to frontal cyclone type, which are all developed from the intersection of cold shear line, warm mesoscale convergence line and the gust front of MCS in the west of Dabie Mountains. The low vortex shear-type mesoscale weather system is mainly a local mesoscale vortex, newly born in boundary layer in Jianghan-Dongting Lake Plain in the eastern Wuling Mountains of Hunan and Hubei and the scale is about 150-300 km. Its formation is accompanied by the strong convergence of multiple flows in the boundary layer and the development of local baroclinicity. The strengthening of the southwest vortex and the formation of heavy precipitation in front of the second-order regional vortex in the west of Hunan and Hubei are the main inducements for the development of local mesoscale vortex in the boundary layer of the eastern plain. The horseshoe-shaped terrain in the middle reaches of the Yangtze River, which is conducive to the convergence of multiple air streams, is the key factor for the occurrence of local mesoscale vortex in the eastern plain. The formation and development of the extreme rainstorm mesoscale weather system in the warm sector of the weakly forced Meiyu front is mainly related to the enhanced convergence and maintenance of the thunderstorm cold pool countercurrent on the westside of the Dabie Mountains and the nighttime boundary layer ultra-low-level jet.
By using conventional observation data, automatic meteorological station data and NCEP reanalysis data, as well as the data of CINRAD and meteorological satellite, the mesoscale weather system development models in the boundary layer of extreme rainstorm under three different weather types are summarized, based on the systematic analysis about the dynamic and thermal characteristics of the boundary layer mesoscale weather system in 39 cases of extreme rainstorms. The results show that the mesoscale weather systems in extreme rainstorm share the same regularity under the same weather system. The occurrence of extreme rainstorm is closely related to the strong development of mesoscale weather system in boundary layer. The special topography in the middle reaches of the Yangtze River plays an important role in the occurrence and development of mesoscale weather systems. By the trigger and organization of strong developing mesoscale weather system in boundary layer under the background of favorable circulation, the consolidation strengthening, stagnation, backward propagation of mesoscale convective system (MCS) and convective cell train effect are important reasons for extreme heavy rainfalls. To be specific, there are three paterns of surface mesoscale synoptic systems related to frontal cyclone type, which are all developed from the intersection of cold shear line, warm mesoscale convergence line and the gust front of MCS in the west of Dabie Mountains. The low vortex shear-type mesoscale weather system is mainly a local mesoscale vortex, newly born in boundary layer in Jianghan-Dongting Lake Plain in the eastern Wuling Mountains of Hunan and Hubei and the scale is about 150-300 km. Its formation is accompanied by the strong convergence of multiple flows in the boundary layer and the development of local baroclinicity. The strengthening of the southwest vortex and the formation of heavy precipitation in front of the second-order regional vortex in the west of Hunan and Hubei are the main inducements for the development of local mesoscale vortex in the boundary layer of the eastern plain. The horseshoe-shaped terrain in the middle reaches of the Yangtze River, which is conducive to the convergence of multiple air streams, is the key factor for the occurrence of local mesoscale vortex in the eastern plain. The formation and development of the extreme rainstorm mesoscale weather system in the warm sector of the weakly forced Meiyu front is mainly related to the enhanced convergence and maintenance of the thunderstorm cold pool countercurrent on the westside of the Dabie Mountains and the nighttime boundary layer ultra-low-level jet.
2022, 48(8):1020-1031.
DOI: 10.7519/j.issn.1000-0526.2022.032102
Abstract:
Using the vorticity-related data collected from the gradient observation tower in the Wuying Forest Ecological Monitoring Station of China Meteorological Administration, this paper addresses the turbulence characteristics of the underlying surface of the forest (turbulence intensity, turbulence variance, etc.), and calculates the zero-plane displacement （d）, the roughness length （z0） and the momentum drag coefficient （CD）. The results indicate that southwest wind prevails almost throughout the year, with northeast wind only in summer. The tubulence intensity during the growing season (May-September) is stronger, turbulence intensity during the non-growing season (October-April) is weaker, the average turbulence intensity of the horizontal wind speed is 0.4, and the vertical wind speed is 0.16. Both d and z0 have obvious seasonal changes, and they consistently show a trend of high in the growing season but low in the non-growing season, with the average values of d and z0 being 18.56 m and 1.21 m, respectively. Under unstable conditions, the standard deviation of wind speed all conforms to 1/3 power similar law; when nearing neutral conditions, the dimensionless three-dimensional wind speed standard deviation σi/u*(i=u,v,w) are 2.81, 2.73, 1.20 in spring; 2.62, 2.53, 1.10 in summer; 2.63, 2.51, 1.14 in autumn; and 2.74, 2.54, 1.17 in winter. The standard deviations of temperature and humidity conform to -1/3 power similar law under unstable conditions, the coefficients for spring fitting are 2.06 and 2.67, 2.45 and 2.18 in summer, 1.94 and 2.85 in autumn, 1.96 and 3.00 in winter, respectively. CD reaches its peak value in weak instability, and the overall average is 9.8×10-3, increasing approximately linearly with roughness.
Using the vorticity-related data collected from the gradient observation tower in the Wuying Forest Ecological Monitoring Station of China Meteorological Administration, this paper addresses the turbulence characteristics of the underlying surface of the forest (turbulence intensity, turbulence variance, etc.), and calculates the zero-plane displacement （d）, the roughness length （z0） and the momentum drag coefficient （CD）. The results indicate that southwest wind prevails almost throughout the year, with northeast wind only in summer. The tubulence intensity during the growing season (May-September) is stronger, turbulence intensity during the non-growing season (October-April) is weaker, the average turbulence intensity of the horizontal wind speed is 0.4, and the vertical wind speed is 0.16. Both d and z0 have obvious seasonal changes, and they consistently show a trend of high in the growing season but low in the non-growing season, with the average values of d and z0 being 18.56 m and 1.21 m, respectively. Under unstable conditions, the standard deviation of wind speed all conforms to 1/3 power similar law; when nearing neutral conditions, the dimensionless three-dimensional wind speed standard deviation σi/u*(i=u,v,w) are 2.81, 2.73, 1.20 in spring; 2.62, 2.53, 1.10 in summer; 2.63, 2.51, 1.14 in autumn; and 2.74, 2.54, 1.17 in winter. The standard deviations of temperature and humidity conform to -1/3 power similar law under unstable conditions, the coefficients for spring fitting are 2.06 and 2.67, 2.45 and 2.18 in summer, 1.94 and 2.85 in autumn, 1.96 and 3.00 in winter, respectively. CD reaches its peak value in weak instability, and the overall average is 9.8×10-3, increasing approximately linearly with roughness.
2022, 48(8):1032-1042.
DOI: 10.7519/j.issn.1000-0526.2022.040203
Abstract:
Based on the equation of atmospheric pollutant mass conservation, the meteorological factors which affect air pollution are constructed and daily increment of air quality index (AQI) is taken as the object to quantitatively classify the air pollution potential. The atmospheric circulation background is divided into cold, mixed and warm-air circulations in autumn and winter by the Q-type cluster analysis method. Then the meteorological factor and its thresholds for distinguishing three types of atmospheric circulation are studied. Based on autumn-winter atmospheric data during 2017-2019, the five-grade prediction models of pollution potential are established, and the discriminant accuracies are 80.0%, 71.0% and 74.7% for cold, mixed and warm-air circulations respectively by the use of the Bayes discriminant analysis method. The mean accuracy of three air types reaches 75.2%. When the five-grade prediction models of pollution potential are tested with autumn-winter atmospheric data during 2015-2017, the mean accuracy of the three air types can reach 63.6%. Through comparison of atmospheric self-purification index (ASI) and the results from the five-grade prediction models of pollution potential with daily increment of AQI in autumn and winter from 2019 to 2021, the five-grade prediction models of pollution potential discriminant results are more consistent with the daily increment trend of AQI than ASI, and the correlation coefficient exceeds 0.67. The correct times of the five-grade prediction models of pollution potential for extremely favorable and extremely unfavorable pollutant diffusions are significantly more than by AQI.
Based on the equation of atmospheric pollutant mass conservation, the meteorological factors which affect air pollution are constructed and daily increment of air quality index (AQI) is taken as the object to quantitatively classify the air pollution potential. The atmospheric circulation background is divided into cold, mixed and warm-air circulations in autumn and winter by the Q-type cluster analysis method. Then the meteorological factor and its thresholds for distinguishing three types of atmospheric circulation are studied. Based on autumn-winter atmospheric data during 2017-2019, the five-grade prediction models of pollution potential are established, and the discriminant accuracies are 80.0%, 71.0% and 74.7% for cold, mixed and warm-air circulations respectively by the use of the Bayes discriminant analysis method. The mean accuracy of three air types reaches 75.2%. When the five-grade prediction models of pollution potential are tested with autumn-winter atmospheric data during 2015-2017, the mean accuracy of the three air types can reach 63.6%. Through comparison of atmospheric self-purification index (ASI) and the results from the five-grade prediction models of pollution potential with daily increment of AQI in autumn and winter from 2019 to 2021, the five-grade prediction models of pollution potential discriminant results are more consistent with the daily increment trend of AQI than ASI, and the correlation coefficient exceeds 0.67. The correct times of the five-grade prediction models of pollution potential for extremely favorable and extremely unfavorable pollutant diffusions are significantly more than by AQI.
2022, 48(8):1043-1052.
DOI: 10.7519/j.issn.1000-0526.2022.041101
Abstract:
With finely zoning of the Yangtze River Basin and based on ECMWF， NCEP， CMA-GFS， GERMAN，CMA-MESO and CMA-SH9 precipitation forecast products, the rolling tests of finely zoning, time division and precipitation classification are carried out to obtain the corresponding model performance ranking. The “neighborhood optimization method” is used for heavy rain and above, and the “point-to-point optimization method” is used for moderate rain and below to establish the optimal integration scheme. The ensemble forecast and statistical analysis results are used to reduce the empty forecast rate of heavy rainfall and light rain. Finally, the multi-model dynamic integrated precipitation products (MDI) are obtained. MDI-14, MDI-21, MDI-28 and MDI-35 are produced during the 14 d, 21 d, 28 d and 35 d sliding training periods respectively. The application analysis shows that MDI have obvious advantages in precipitation forecasts, among which MDI-28 has the best effect in predicting heavy rain and above, and especially, its 24 h TS-score is 0.051-0.141 higher than that of the others; MDI-35 has the best effect in predicting moderate rain and below, with the 24 h TS-score being 0.006-0.117 higher than that of the others, and empty and missing forecast rate are also controlled well. Comparing the spatial distribution of TS scores of 24 h precipitation forecasts between MDI and ECMWF, we find that the former is higher than that of the latter in most areas of the Yangtze River Basin. Especially, for heavy rain and above, it is 0.05-0.26 higher in the east regions of the upper reaches of Yangtze River as well as in the middle and northern regions of the middle and lower reaches of Yangtze River.
With finely zoning of the Yangtze River Basin and based on ECMWF， NCEP， CMA-GFS， GERMAN，CMA-MESO and CMA-SH9 precipitation forecast products, the rolling tests of finely zoning, time division and precipitation classification are carried out to obtain the corresponding model performance ranking. The “neighborhood optimization method” is used for heavy rain and above, and the “point-to-point optimization method” is used for moderate rain and below to establish the optimal integration scheme. The ensemble forecast and statistical analysis results are used to reduce the empty forecast rate of heavy rainfall and light rain. Finally, the multi-model dynamic integrated precipitation products (MDI) are obtained. MDI-14, MDI-21, MDI-28 and MDI-35 are produced during the 14 d, 21 d, 28 d and 35 d sliding training periods respectively. The application analysis shows that MDI have obvious advantages in precipitation forecasts, among which MDI-28 has the best effect in predicting heavy rain and above, and especially, its 24 h TS-score is 0.051-0.141 higher than that of the others; MDI-35 has the best effect in predicting moderate rain and below, with the 24 h TS-score being 0.006-0.117 higher than that of the others, and empty and missing forecast rate are also controlled well. Comparing the spatial distribution of TS scores of 24 h precipitation forecasts between MDI and ECMWF, we find that the former is higher than that of the latter in most areas of the Yangtze River Basin. Especially, for heavy rain and above, it is 0.05-0.26 higher in the east regions of the upper reaches of Yangtze River as well as in the middle and northern regions of the middle and lower reaches of Yangtze River.
2022, 48(8):1053-1061.
DOI: 10.7519/j.issn.1000-0526.2022.010601
Abstract:
With the bright prospects of application of large unmanned aerial vehicles (UAV) in artificial precipitation enhancement operation, an UAV artificial precipitation enhancement experiment was carried out in Qilian Mountains.This paper discusses the UAV operating performance and analyzes the change characteristics of the microphysical parameters during the cloud seeding processes on 27 October 2020. The results show that the UAV has the ability of large-scale artificial precipitation enhancement and detection with more than 5 h endurance and good anti-deicing and crosswind resistance capabilities. After the cloud seeding processes, concentration and diameter of cloud particles get increased in every level, and the concentration of low-level cloud particles is significantly higher than that of high level. The change of cloud microphysical characteristics before and after seeding operation is related to cloud position and time to select. Within 20-30 min after the seeding, the concentration of the number of raindrops at the ground decreased at first and then increased, while the effective diameter of the particles continued to increase. The cloud particle spectrum showed the characteristics of an increase in large cloud particles, and the precipitation particle spectrum was broadened.
With the bright prospects of application of large unmanned aerial vehicles (UAV) in artificial precipitation enhancement operation, an UAV artificial precipitation enhancement experiment was carried out in Qilian Mountains.This paper discusses the UAV operating performance and analyzes the change characteristics of the microphysical parameters during the cloud seeding processes on 27 October 2020. The results show that the UAV has the ability of large-scale artificial precipitation enhancement and detection with more than 5 h endurance and good anti-deicing and crosswind resistance capabilities. After the cloud seeding processes, concentration and diameter of cloud particles get increased in every level, and the concentration of low-level cloud particles is significantly higher than that of high level. The change of cloud microphysical characteristics before and after seeding operation is related to cloud position and time to select. Within 20-30 min after the seeding, the concentration of the number of raindrops at the ground decreased at first and then increased, while the effective diameter of the particles continued to increase. The cloud particle spectrum showed the characteristics of an increase in large cloud particles, and the precipitation particle spectrum was broadened.
10 Effect of Environmental Humidity on the Allergic Rhinitis—A Study of Three Cities in Gansu Province
LI Lanyu
,
LUO Bin
,
WANG Bo
,
LI Yanlin
,
WANG Shunxia
,
XU Shenggang
,
LI Sheng
,
ZHOU Ji
,
NIU Jingping
2022, 48(8):1062-1069.
DOI: 10.7519/j.issn.1000-0526.2022.060101
Abstract:
With the data of daily outpatient visits of allergic rhinitis, air pollution and meteorological data in the three cities of Lanzhou (2014-2016), Tianshui (2016-2018) and Zhangye (2016-2018), this study analyzes the relationship between relative humidity (RH), absolute humidity (AH) and the daily outpatient visits of allergic rhinitis. In the three cities, the peak period of daily outpatient visits for allergic rhinitis is from August to September. The decrease in RH could lead to significant increase in outpatient visits for allergic rhinitis in the three cities. With the each 1% decrease of RH, the outpatients visit for allergic rhinitis in Lanzhou, Tianshui and Zhangye could increase by 1.36%, 2.30% and 1.50%, respectively, while the outpatients visit for allergic rhinities in the three cities have the increase of 14.92%, 16.00% and 13.98% accordingly for each 1 g·m-3 decrease in AH. Our study suggests that the onset of allergic rhinitis is negatively associated with atmospheric environmental humidity, and the dry and lowhumidity environment is an important risk factor for allergic rhinitis in arid area. Compared with RH, AH could better reflect the effect of environmental humidity on allergic rhinitis
With the data of daily outpatient visits of allergic rhinitis, air pollution and meteorological data in the three cities of Lanzhou (2014-2016), Tianshui (2016-2018) and Zhangye (2016-2018), this study analyzes the relationship between relative humidity (RH), absolute humidity (AH) and the daily outpatient visits of allergic rhinitis. In the three cities, the peak period of daily outpatient visits for allergic rhinitis is from August to September. The decrease in RH could lead to significant increase in outpatient visits for allergic rhinitis in the three cities. With the each 1% decrease of RH, the outpatients visit for allergic rhinitis in Lanzhou, Tianshui and Zhangye could increase by 1.36%, 2.30% and 1.50%, respectively, while the outpatients visit for allergic rhinities in the three cities have the increase of 14.92%, 16.00% and 13.98% accordingly for each 1 g·m-3 decrease in AH. Our study suggests that the onset of allergic rhinitis is negatively associated with atmospheric environmental humidity, and the dry and lowhumidity environment is an important risk factor for allergic rhinitis in arid area. Compared with RH, AH could better reflect the effect of environmental humidity on allergic rhinitis
2022, 48(8):1070-1076.
DOI: 10.7519/j.issn.1000-0526.2022.070901
Abstract:
The main characteristic of the general atmospheric circulation in May 2022 is that the single polar vortex center in the Northern Hemisphere was stronger than usual. The circulation finished the transition from a three-wave pattern to a four-wave pattern, the 500 hPa geopotential height presented the distribution of a four-wave pattern in middle-high latitudes of the Northern Hemisphere, and the degree of meridionality was stonger than normal. The strength of Western Pacific subtropical high and the south branch trough were similar to those in normal years. The monthly mean temperature was 16.7°C, 0.2°C higher than normal. The monthly mean precipitation amount was 71.6 mm, 2% more than normal, of which the precipitation in Southwest China and South China was significantly more than in the normal year. Four regional rainfall processes occurred in China this month and several provinces were attacked by gales and hailstorm, which led to economic losses and casualties to some degrees. In addition, three cold air processes occurred this month, and the northern part of China experienced three sand-dust weather events. The drought maintained or developed in the Huanghuai and Jianghuai Regions.
The main characteristic of the general atmospheric circulation in May 2022 is that the single polar vortex center in the Northern Hemisphere was stronger than usual. The circulation finished the transition from a three-wave pattern to a four-wave pattern, the 500 hPa geopotential height presented the distribution of a four-wave pattern in middle-high latitudes of the Northern Hemisphere, and the degree of meridionality was stonger than normal. The strength of Western Pacific subtropical high and the south branch trough were similar to those in normal years. The monthly mean temperature was 16.7°C, 0.2°C higher than normal. The monthly mean precipitation amount was 71.6 mm, 2% more than normal, of which the precipitation in Southwest China and South China was significantly more than in the normal year. Four regional rainfall processes occurred in China this month and several provinces were attacked by gales and hailstorm, which led to economic losses and casualties to some degrees. In addition, three cold air processes occurred this month, and the northern part of China experienced three sand-dust weather events. The drought maintained or developed in the Huanghuai and Jianghuai Regions.
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