ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 48,Issue 7,2022 Table of Contents
2022, 48(7):801-812.
DOI: 10.7519/j.issn.1000-0526.2021.101201
Abstract:
The mesoscale characteristics of a local short-time severe convective rainstorm that occurred at the eastern foot of Helan Mountains in Ningxia in August 2019 are analyzed based on the data from Himawari-8 satellite, C-band Doppler radar, ERA5 hourly reanalysis, automatic weather station and conventional observation data. The results show that the southerly jet at 700 hPa, which was formed 6 h before the rainstorm and strengthened at night, contributed to the high temperature, the high humidity, the enhancement of atmospheric instability and the dynamic and thermal uplift mechanisms in the lower layers of the rainstorm area. It also helped mesoscale ground convergence line to trigger the meso-β scale convective system in the eastern slope of Helan Mountains and strengthen it into meso-α scale convective system, leading to the generation and development of the severe convective rainstorm eventually. The rainstorm occurred in the front-left of jet axis at 700 hPa, the high humidity area with water vapor flux ≥6 g·cm-1·s-1·hPa-1 at 700 hPa and specific humidity ≥12 g·kg-1 at 850 hPa, the high energy area with convective available potential energy (CAPE) ≥1 〖KG-*5〗500 J·kg-1, the high temperature area with θse ≥346 K at 850 hPa, the vertical upwarding area with central intensity ≤-1.2 Pa·s-1 at 800 hPa, and the front of cold cloud where the large gradient (G) of radiation brightness temperature (TBB) occurred. During the heaviest rainfall period, the jet axis was closest to the rainstorm area, the TBB ≤-66℃, G ≥27℃·km-1, the radar echo intensity (Z) ≥65 dBz, the echo heights (H) ≥10 km, the vertical integrated liquid water (VIL) ≥11 kg·m-2, and the area of the cold cloud below -52℃ was about 1/5 of mesoscale convective complex. The lower the TBB, the large the G, the higher the cooling rate and the more the hourly precipitation. The minimum TBB, the maximum G, the leap of Z and VIL, and the increase of echo height appeared 10-20 min earlier than the maximum rainfall, and the mesoscale ground convergence line appeared 30 min earlier than the rainfall.
The mesoscale characteristics of a local short-time severe convective rainstorm that occurred at the eastern foot of Helan Mountains in Ningxia in August 2019 are analyzed based on the data from Himawari-8 satellite, C-band Doppler radar, ERA5 hourly reanalysis, automatic weather station and conventional observation data. The results show that the southerly jet at 700 hPa, which was formed 6 h before the rainstorm and strengthened at night, contributed to the high temperature, the high humidity, the enhancement of atmospheric instability and the dynamic and thermal uplift mechanisms in the lower layers of the rainstorm area. It also helped mesoscale ground convergence line to trigger the meso-β scale convective system in the eastern slope of Helan Mountains and strengthen it into meso-α scale convective system, leading to the generation and development of the severe convective rainstorm eventually. The rainstorm occurred in the front-left of jet axis at 700 hPa, the high humidity area with water vapor flux ≥6 g·cm-1·s-1·hPa-1 at 700 hPa and specific humidity ≥12 g·kg-1 at 850 hPa, the high energy area with convective available potential energy (CAPE) ≥1 〖KG-*5〗500 J·kg-1, the high temperature area with θse ≥346 K at 850 hPa, the vertical upwarding area with central intensity ≤-1.2 Pa·s-1 at 800 hPa, and the front of cold cloud where the large gradient (G) of radiation brightness temperature (TBB) occurred. During the heaviest rainfall period, the jet axis was closest to the rainstorm area, the TBB ≤-66℃, G ≥27℃·km-1, the radar echo intensity (Z) ≥65 dBz, the echo heights (H) ≥10 km, the vertical integrated liquid water (VIL) ≥11 kg·m-2, and the area of the cold cloud below -52℃ was about 1/5 of mesoscale convective complex. The lower the TBB, the large the G, the higher the cooling rate and the more the hourly precipitation. The minimum TBB, the maximum G, the leap of Z and VIL, and the increase of echo height appeared 10-20 min earlier than the maximum rainfall, and the mesoscale ground convergence line appeared 30 min earlier than the rainfall.
ZHI Jiangling
,
HUANG Xianxiang
,
GU Bohui
,
CAI Kanglong
,
LI Cailing
,
ZHANG Jingjing
,
LI Zhaoming
2022, 48(7):813-825.
DOI: 10.7519/j.issn.1000-0526.2022.040802
Abstract:
One supercell triggered severe thunderstorm gales in the Pearl River Delta on 11 April 2019 and another supercell induced an EF3 strong tornado in Xuwen County of Zhanjiang City on 13 April 2019. Based on multi-source observations, the synoptic situation, ambient conditions, structure of the storm,triggering characteristics of convective storm, and formation of the severe thunderstorm gale and tornado in the two events are comparatively analyzed.The results are as follows. The severe thunderstorm gales occurred under the southward shear line in the lower layers and the surface cold front, which was classified as the baroclinic frontogenesis severe convection. The strong tornado was the southerly warm advection forcing sector severe convection. The ambient conditions in both days were characterized by high energy strong 0-6 km vertical wind shear, low lifting condensation height and the stratification of dry in the upper level and wet in the lower level. But the sounding at Qingyuan Station on 11 April shows that 0-1 km vertical wind shear was small and average depression of the dew point was 29.2℃ in middle levels. This condition was favorable for the formation of strong downdraft. However, the sounding at Haikou Station on 13 April shows that strong 0-1 km vertical wind shear was favorable for the tornado. On 11 April, the thunderstorm gales were located at the core of the supercell. The low-level mesocyclone was weaker and had a larger diameter of 6-7 km. The rotation depth of mesocyclone was below 2 km. On 13 April, the tornado occured at the top of the hook echo accompanied by low-level intense mesocyclone with the minimum diameter of 2 km and tornadic vortex signature. The rotation depth mesocyclone was up to 6 km. Vertical vorticity remained unchanged at the order of 10-2 s-1 before and after the thunderstorm gales. However, the tornado occurred during the magnitude of low-level mesocyclone vertical vorticity increased to be 10-1 s-1 rapidly, which was an order of magnitude larger than the vertical vorticity of strong thunderstorm gale event. The strong downdraft of the storm produced a large area of intense cold pool on the ground on 11 April, which was favorable for the formation of thunderstorm gales. The saturated atmosphere on the ground and the less strong downdraft of the storm were conducive to the occurrence of strong tornado.
One supercell triggered severe thunderstorm gales in the Pearl River Delta on 11 April 2019 and another supercell induced an EF3 strong tornado in Xuwen County of Zhanjiang City on 13 April 2019. Based on multi-source observations, the synoptic situation, ambient conditions, structure of the storm,triggering characteristics of convective storm, and formation of the severe thunderstorm gale and tornado in the two events are comparatively analyzed.The results are as follows. The severe thunderstorm gales occurred under the southward shear line in the lower layers and the surface cold front, which was classified as the baroclinic frontogenesis severe convection. The strong tornado was the southerly warm advection forcing sector severe convection. The ambient conditions in both days were characterized by high energy strong 0-6 km vertical wind shear, low lifting condensation height and the stratification of dry in the upper level and wet in the lower level. But the sounding at Qingyuan Station on 11 April shows that 0-1 km vertical wind shear was small and average depression of the dew point was 29.2℃ in middle levels. This condition was favorable for the formation of strong downdraft. However, the sounding at Haikou Station on 13 April shows that strong 0-1 km vertical wind shear was favorable for the tornado. On 11 April, the thunderstorm gales were located at the core of the supercell. The low-level mesocyclone was weaker and had a larger diameter of 6-7 km. The rotation depth of mesocyclone was below 2 km. On 13 April, the tornado occured at the top of the hook echo accompanied by low-level intense mesocyclone with the minimum diameter of 2 km and tornadic vortex signature. The rotation depth mesocyclone was up to 6 km. Vertical vorticity remained unchanged at the order of 10-2 s-1 before and after the thunderstorm gales. However, the tornado occurred during the magnitude of low-level mesocyclone vertical vorticity increased to be 10-1 s-1 rapidly, which was an order of magnitude larger than the vertical vorticity of strong thunderstorm gale event. The strong downdraft of the storm produced a large area of intense cold pool on the ground on 11 April, which was favorable for the formation of thunderstorm gales. The saturated atmosphere on the ground and the less strong downdraft of the storm were conducive to the occurrence of strong tornado.
3 Analysis of Short-Time Severe Rainfall on 4 September 2020 Detected by Phased Array Radar in Foshan
2022, 48(7):826-839.
DOI: 10.7519/j.issn.1000-0526.2022.032801
Abstract:
To study whether the phased array radar with high temporal and spatial resolution can accurately detect the evolution of heavy precipitation, the quality control of Foshan X-band phased array weather radar (PAWR) data is used to analyze a local short-time severe rainfall that occurred in Nanhai District of Foshan City, Guangdong Province on 4 September 2020. The intensity field and three-dimensional wind field structure of multi-cell storms in Nanhai District from 16:00 BT to 17:30 BT are analyzed, and the relationship between the intensity field, three-dimensional wind field and the precipitation is explored. The results show that PAWR can provide more precise observations of severe convective weather. In the merging stage, the initiation, splitting and merging processes of multiple convective cells on small scale and within short period of time are observed. In terms of the mature stage, the formation process of meso-γ scale cyclone, the structural characteristics of the intensity field, three-dimensional wind field, divergence field and vorticity field during the cyclone convergence period are discussed. In the extinction stage, the structural characteristics of the formation and enhancement process of meso-γ scale anticyclones are analyzed. After the disappearance of cyclone and anticyclone, the convective cells rapidly die out. In addition, based on the statistics obtained from the intensity field and three-dimensional wind field with high spatial and temporal resolution, it is found that the reflectivity factor and horizontal wind speed change significantly in 10-15 min before precipitation and in 5-10 min before the 5 min heaviest precipitation observed by automatic weather stations.The results of this study would have a predictive effect on the monitoring and early warning of short-time severe precipitation, and provide some references for the phased array radar with high temporal and spatial resolution to finely detect the evolution of severe precipitation.
To study whether the phased array radar with high temporal and spatial resolution can accurately detect the evolution of heavy precipitation, the quality control of Foshan X-band phased array weather radar (PAWR) data is used to analyze a local short-time severe rainfall that occurred in Nanhai District of Foshan City, Guangdong Province on 4 September 2020. The intensity field and three-dimensional wind field structure of multi-cell storms in Nanhai District from 16:00 BT to 17:30 BT are analyzed, and the relationship between the intensity field, three-dimensional wind field and the precipitation is explored. The results show that PAWR can provide more precise observations of severe convective weather. In the merging stage, the initiation, splitting and merging processes of multiple convective cells on small scale and within short period of time are observed. In terms of the mature stage, the formation process of meso-γ scale cyclone, the structural characteristics of the intensity field, three-dimensional wind field, divergence field and vorticity field during the cyclone convergence period are discussed. In the extinction stage, the structural characteristics of the formation and enhancement process of meso-γ scale anticyclones are analyzed. After the disappearance of cyclone and anticyclone, the convective cells rapidly die out. In addition, based on the statistics obtained from the intensity field and three-dimensional wind field with high spatial and temporal resolution, it is found that the reflectivity factor and horizontal wind speed change significantly in 10-15 min before precipitation and in 5-10 min before the 5 min heaviest precipitation observed by automatic weather stations.The results of this study would have a predictive effect on the monitoring and early warning of short-time severe precipitation, and provide some references for the phased array radar with high temporal and spatial resolution to finely detect the evolution of severe precipitation.
2022, 48(7):840-855.
DOI: 10.7519/j.issn.1000-0526.2022.032502
Abstract:
Based on the precipitation forecast data of convection-permitting ensemble prediction system and observation data from April to September in 2017, 2018 and 2019, the effects of 24 h accumulated precipitation forecast of ensemble members in eastern Sichuan Basin are verified and compared, and the performance of different physical parameterization schemes is further discussed. Results show that the ensemble average forecast and probability matching forecast have obvious advantages over the ensemble members. The schemes is relatively good, while the critical success index (CSI) score of Grell 3D ensemble (G3) scheme is relatively low after 48 h. Thompson and Morrison microphysical parameterization schemes are better for light rain than WRF Single-Moment 6-class (WSM6) scheme, while WSM6 scheme is better for moderate rain, and there is no significant difference in the CSI scores of heavy rain and rainstorm among the three schemes. The CSI score of Mellor-Yamada-Janjic (MYJ) and Mellor-Yamada-Nakanishi-Niino (MYNN) boundary layer schemes is higher than that of Yonsei University (YSU) scheme, especially after 48 h. However, YSU scheme is mostly used in combination with G3 scheme, so its low score is mainly affected by G3. The precipitation distribution characteristics of all these schemes are similar to those of observation, but the false strong rain belt is predicted in Huaying Mountain, Wuling Mountain and Dalou Mountain, and the precipitation from the middle to the northeast of Chongqing is underestimated. The precipitation forecast in eastern Sichuan Basin is most sensitive to cumulus parameterization scheme. After adjusting one member’s G3 scheme to KF scheme, not only the forecast score is significantly improved, but also the ensemble spread is increased, and the skill of probability forecast is improved. prediction performance of Kain-Fritsch (KF) and Betts-Miller-Janjic (BMJ) cumulus parameterization
Based on the precipitation forecast data of convection-permitting ensemble prediction system and observation data from April to September in 2017, 2018 and 2019, the effects of 24 h accumulated precipitation forecast of ensemble members in eastern Sichuan Basin are verified and compared, and the performance of different physical parameterization schemes is further discussed. Results show that the ensemble average forecast and probability matching forecast have obvious advantages over the ensemble members. The schemes is relatively good, while the critical success index (CSI) score of Grell 3D ensemble (G3) scheme is relatively low after 48 h. Thompson and Morrison microphysical parameterization schemes are better for light rain than WRF Single-Moment 6-class (WSM6) scheme, while WSM6 scheme is better for moderate rain, and there is no significant difference in the CSI scores of heavy rain and rainstorm among the three schemes. The CSI score of Mellor-Yamada-Janjic (MYJ) and Mellor-Yamada-Nakanishi-Niino (MYNN) boundary layer schemes is higher than that of Yonsei University (YSU) scheme, especially after 48 h. However, YSU scheme is mostly used in combination with G3 scheme, so its low score is mainly affected by G3. The precipitation distribution characteristics of all these schemes are similar to those of observation, but the false strong rain belt is predicted in Huaying Mountain, Wuling Mountain and Dalou Mountain, and the precipitation from the middle to the northeast of Chongqing is underestimated. The precipitation forecast in eastern Sichuan Basin is most sensitive to cumulus parameterization scheme. After adjusting one member’s G3 scheme to KF scheme, not only the forecast score is significantly improved, but also the ensemble spread is increased, and the skill of probability forecast is improved. prediction performance of Kain-Fritsch (KF) and Betts-Miller-Janjic (BMJ) cumulus parameterization
2022, 48(7):856-867.
DOI: 10.7519/j.issn.1000-0526.2022.050702
Abstract:
Using the S-band dual polarization radar data and the surface precipitation phenomenon instrument data, the process of a hailstorm with severe convective weather in Yongding District of Longyan, Fujian Province on 27 March 2020 is analyzed, and compared with the characteristics of short-term heavy precipitation that occurred in Zhangping of Longyan at a similar time. The results show that the echo height of hail cloud in Yongding jumped before the hail shooting.There was a bounded weak echo in the front of the cloud moving direction, and the ZDR arc with an intensity of 2-4 dB also appeared there. The KDP column developed highly within the hailstorm simultaneously, up to 7-8 km. The KDP column also appeared in the heavy rainfall cloud in Zhangping, but its height 〖JP2〗was lower. There were hailstones aloft in Zhangping, but heavy rainfalls with large raindrops appeared on the ground for hailstones melting during falling. In the front of these two severe convective clouds, the large drop (>3 mm) ends increased firstly with raindrop spectrum boarding, showing double or multi-peaks. While the strong center of convective cloud was moving closer, the concentration of small rain drops (≤1 mm) increased in magnitude, which was related to the separate fall tracks of large and small raindrops caused by the strong environmental vertical wind shear in the front of convective cloud. In the hail shooting or heavy precipitation stage, the hailstones had low density and the raindrop spectrums showed weak double peaks at Yongding Station, while single-peak presented at Zhangping Station. The large drops at the two stations in this stage were mostly caused by the melting from small hails. The double-peak structure of the raindrop spectrum after hail shooting was mainly caused by the collision of raindrops. The raindrop spectrums at the tail of the cloud became narrow, decreasing in magnitude with small particles.
Using the S-band dual polarization radar data and the surface precipitation phenomenon instrument data, the process of a hailstorm with severe convective weather in Yongding District of Longyan, Fujian Province on 27 March 2020 is analyzed, and compared with the characteristics of short-term heavy precipitation that occurred in Zhangping of Longyan at a similar time. The results show that the echo height of hail cloud in Yongding jumped before the hail shooting.There was a bounded weak echo in the front of the cloud moving direction, and the ZDR arc with an intensity of 2-4 dB also appeared there. The KDP column developed highly within the hailstorm simultaneously, up to 7-8 km. The KDP column also appeared in the heavy rainfall cloud in Zhangping, but its height 〖JP2〗was lower. There were hailstones aloft in Zhangping, but heavy rainfalls with large raindrops appeared on the ground for hailstones melting during falling. In the front of these two severe convective clouds, the large drop (>3 mm) ends increased firstly with raindrop spectrum boarding, showing double or multi-peaks. While the strong center of convective cloud was moving closer, the concentration of small rain drops (≤1 mm) increased in magnitude, which was related to the separate fall tracks of large and small raindrops caused by the strong environmental vertical wind shear in the front of convective cloud. In the hail shooting or heavy precipitation stage, the hailstones had low density and the raindrop spectrums showed weak double peaks at Yongding Station, while single-peak presented at Zhangping Station. The large drops at the two stations in this stage were mostly caused by the melting from small hails. The double-peak structure of the raindrop spectrum after hail shooting was mainly caused by the collision of raindrops. The raindrop spectrums at the tail of the cloud became narrow, decreasing in magnitude with small particles.
2022, 48(7):868-877.
DOI: 10.7519/j.issn.1000-0526.2022.041202
Abstract:
Based on the air-sounding data, the CIND3830-CC CINRAD data and surface meteorological data, and 21 hail weather processes in Pu’er during 2013-2020， this study gives the difinition to storm cells with hail diameter ≥20 mm as large hail storm cells, storm cells with hail diameter ≥5 mm and less than 20 mm as medium hail storm cells and storm cells with hail diameter <5 mm as small hail storm 〖JP2〗cells (GB/T27957-2011). The Doppler radar echo characteristics of small hail, mdium hail and large hail are comparatively analyzed. The results show that hail storm cells have common characteristics. High top and high bottom structure of the radar echo, height above 5 km and large echo gradient and composite reflectivity (CR)≥55 dBz、VIL≥23 kg·m-2、H45 dBz≥7.5 km、H45 dBz-H0℃≥2.8 km. VIL shows jump phenomenon in 67% hail storm cells, appearing 5-10 min before the occurrence of hail falls. The bigger the magnitude of the jump, the greater the corresponding VIL. The hail storm cells have obvious convergence characteristics and large hailstorm cells often have mesocyclone characteristics. All the large hail storm cells are significantly greater than the medium and small hail storm cells in VIL/H. H50 dBz-H-20℃ of most large hail storm cells are significantly greater than those of medium and small hail storm cells. Large hail storm cells in mature stage often lasts significantly longer than medium and small hail storm cells. The echo overhang structure of large hail storm cells is often more than the medium and small hail storm cells, and DVIL and the rotation speed are often greater than medium and small hail storm cells. ET, VIL jump characteristics, TBSS and V-notch can not be used as indicators to identify different grades of hails.
Based on the air-sounding data, the CIND3830-CC CINRAD data and surface meteorological data, and 21 hail weather processes in Pu’er during 2013-2020， this study gives the difinition to storm cells with hail diameter ≥20 mm as large hail storm cells, storm cells with hail diameter ≥5 mm and less than 20 mm as medium hail storm cells and storm cells with hail diameter <5 mm as small hail storm 〖JP2〗cells (GB/T27957-2011). The Doppler radar echo characteristics of small hail, mdium hail and large hail are comparatively analyzed. The results show that hail storm cells have common characteristics. High top and high bottom structure of the radar echo, height above 5 km and large echo gradient and composite reflectivity (CR)≥55 dBz、VIL≥23 kg·m-2、H45 dBz≥7.5 km、H45 dBz-H0℃≥2.8 km. VIL shows jump phenomenon in 67% hail storm cells, appearing 5-10 min before the occurrence of hail falls. The bigger the magnitude of the jump, the greater the corresponding VIL. The hail storm cells have obvious convergence characteristics and large hailstorm cells often have mesocyclone characteristics. All the large hail storm cells are significantly greater than the medium and small hail storm cells in VIL/H. H50 dBz-H-20℃ of most large hail storm cells are significantly greater than those of medium and small hail storm cells. Large hail storm cells in mature stage often lasts significantly longer than medium and small hail storm cells. The echo overhang structure of large hail storm cells is often more than the medium and small hail storm cells, and DVIL and the rotation speed are often greater than medium and small hail storm cells. ET, VIL jump characteristics, TBSS and V-notch can not be used as indicators to identify different grades of hails.
2022, 48(7):878-890.
DOI: 10.7519/j.issn.1000-0526.2022.031001
Abstract:
Based on the weather radar and radiosonde data, a widely used thunderstorm identification and extrapolation algorithm is used in this paper to compare the characteristic difference of probability frequency and membership for thunderstorms with or without cloud-to-ground (CG) lightning activity, and a one-hour warning method is established on the principle of fuzzy logic by extracting the radar parameters. The analysis results show that the maximum radar reflectivities in the -25℃ to -10℃ layer and at the of echo top (ET) are the best factors for CG warning in Hubei Province. In particular, REF-15℃, REF-20℃ and REF-25℃ have the best performance, followed by REF-10℃. By contrast, vertically integrated liquid is less indicative of lightning activity. Thus, according to the different contributions of these factors, the unequal weight distribution is given, and the dynamic weight coefficient is used to finally achieve the location forecast of CG lightning in the future one hour. In addition, the 1 km grid point-to-point verification is performed by using the 1 h (6 min interval) nowcasts and in-site observations, and the results indicate that the probability of detection (POD) can reach more than 50% in 30 min, and the critical success index (CSI) is about 30%. However, POD and CSI decrease slowly with the increasing lead time of forecasts. Through the test of individual forecast case, it is found that this method is more suitable for the large-scale thunderstorm system, but relatively poor for local convective system. This 〖JP2〗finding illustrates that the fuzzy〖JP〗 logic CG lightning warning method based on radar parameters is reasonable 〖JP2〗and reliable, and can be used for automatic warning and decision-making service in Hubei Province.height
Based on the weather radar and radiosonde data, a widely used thunderstorm identification and extrapolation algorithm is used in this paper to compare the characteristic difference of probability frequency and membership for thunderstorms with or without cloud-to-ground (CG) lightning activity, and a one-hour warning method is established on the principle of fuzzy logic by extracting the radar parameters. The analysis results show that the maximum radar reflectivities in the -25℃ to -10℃ layer and at the of echo top (ET) are the best factors for CG warning in Hubei Province. In particular, REF-15℃, REF-20℃ and REF-25℃ have the best performance, followed by REF-10℃. By contrast, vertically integrated liquid is less indicative of lightning activity. Thus, according to the different contributions of these factors, the unequal weight distribution is given, and the dynamic weight coefficient is used to finally achieve the location forecast of CG lightning in the future one hour. In addition, the 1 km grid point-to-point verification is performed by using the 1 h (6 min interval) nowcasts and in-site observations, and the results indicate that the probability of detection (POD) can reach more than 50% in 30 min, and the critical success index (CSI) is about 30%. However, POD and CSI decrease slowly with the increasing lead time of forecasts. Through the test of individual forecast case, it is found that this method is more suitable for the large-scale thunderstorm system, but relatively poor for local convective system. This 〖JP2〗finding illustrates that the fuzzy〖JP〗 logic CG lightning warning method based on radar parameters is reasonable 〖JP2〗and reliable, and can be used for automatic warning and decision-making service in Hubei Province.height
2022, 48(7):891-898.
DOI: 10.7519/j.issn.1000-0526.2022.041201
Abstract:
The observation of the microstructure of rainfall is very important for the accurate prediction of precipitation and weather modification. However, due to factors such as nonprecipitation factors, turbulence and raindrop overlap, there exist certain errors in the quality of the current raindrop spectrum observation data. This paper selects 9 national meteorological observation stations in Beijing from the Parsivel disdrometer observation data from April to October 2017, combined with the tippingbucket gauge rainfall observation data and manual record weather phenomenon, and studies the quality control method of disdrometer observation data. The results show that the wrong disdrometer observation data are mainly caused by haze, sanddust weather and insect activities. The particle velocity is mainly below 5 m·s-1, and the drop size distribution is relatively scattered. Through the speed threshold and quantity threshold (STQT) quality control methods, the wrong disdrometer observation data can be effectively eliminated. When the 0.4 speed threshold coefficient and 0.7 quantity threshold coefficient are used respectively, the best threat score is 0.92. After using STQT method for disdrometer observation data quality control, the correlation coefficient between disdrometer observation precipitation and tippingbucket gauge observation precipitation increases from 0.757 to 0.985. Thus, this method can make more effective use of rainfall observation data and give full play to the benefit of new observing equipment.
The observation of the microstructure of rainfall is very important for the accurate prediction of precipitation and weather modification. However, due to factors such as nonprecipitation factors, turbulence and raindrop overlap, there exist certain errors in the quality of the current raindrop spectrum observation data. This paper selects 9 national meteorological observation stations in Beijing from the Parsivel disdrometer observation data from April to October 2017, combined with the tippingbucket gauge rainfall observation data and manual record weather phenomenon, and studies the quality control method of disdrometer observation data. The results show that the wrong disdrometer observation data are mainly caused by haze, sanddust weather and insect activities. The particle velocity is mainly below 5 m·s-1, and the drop size distribution is relatively scattered. Through the speed threshold and quantity threshold (STQT) quality control methods, the wrong disdrometer observation data can be effectively eliminated. When the 0.4 speed threshold coefficient and 0.7 quantity threshold coefficient are used respectively, the best threat score is 0.92. After using STQT method for disdrometer observation data quality control, the correlation coefficient between disdrometer observation precipitation and tippingbucket gauge observation precipitation increases from 0.757 to 0.985. Thus, this method can make more effective use of rainfall observation data and give full play to the benefit of new observing equipment.
2022, 48(7):899-912.
DOI: 10.7519/j.issn.1000-0526.2022.032802
Abstract:
By using meteorological ground and high-resolution observation data, automatic station data, satellite imagery and ERA5 data, the temporal and spatial distribution characteristics of summer fog in the Beijing-Tianjin-Hebei Region from 2000 to 2019 are analyzed． The conceptual model of summer fog is established, and the typical cases are analyzed. The results show that there are 1-4 days of summer fog every year in most of the Beijing-Tianjin-Hebei Region． Minimum visibility tends to be relatively low when fog appears in the northwest, northeast and southeast of the region． Average minimum visibility from central Zhangjiakou to northwest Baoding, southeast Baoding to central Cangzhou and Hengshui areas can decrease to as low as 300 m． The spatial difference of duration of summer fog in plain area is small, generally 1-1.4 days, and the fog duration in mountainous area is relatively longer. The generation and dissipation of fog have obvious diurnal changes. Usually, fog occurs in high frequency in the morning before and after sunrise, and dissipates within 3 hours after sunrise． In summer, when the fog appears, the bottom height of the inversion layer is usually high, the inversion thickness is thin, the temperature difference is small and the intensity is weak. The diurnal temperature range on the ground is above 7℃, and the wind speed is 1-2.4 m·s-1. All these are the important conditions for the formation of fog． The wind direction is mainly southerly or northerly when fog occurs．Three typical conceptual models of summer fog in the Beijing-Tianjin-Hebei Region are radiation fog under the control of high pressure ridge, advection radiation fog under the control of southwest airflow in front of upper trough, and rain fog under the control of subtropical high pressure．
By using meteorological ground and high-resolution observation data, automatic station data, satellite imagery and ERA5 data, the temporal and spatial distribution characteristics of summer fog in the Beijing-Tianjin-Hebei Region from 2000 to 2019 are analyzed． The conceptual model of summer fog is established, and the typical cases are analyzed. The results show that there are 1-4 days of summer fog every year in most of the Beijing-Tianjin-Hebei Region． Minimum visibility tends to be relatively low when fog appears in the northwest, northeast and southeast of the region． Average minimum visibility from central Zhangjiakou to northwest Baoding, southeast Baoding to central Cangzhou and Hengshui areas can decrease to as low as 300 m． The spatial difference of duration of summer fog in plain area is small, generally 1-1.4 days, and the fog duration in mountainous area is relatively longer. The generation and dissipation of fog have obvious diurnal changes. Usually, fog occurs in high frequency in the morning before and after sunrise, and dissipates within 3 hours after sunrise． In summer, when the fog appears, the bottom height of the inversion layer is usually high, the inversion thickness is thin, the temperature difference is small and the intensity is weak. The diurnal temperature range on the ground is above 7℃, and the wind speed is 1-2.4 m·s-1. All these are the important conditions for the formation of fog． The wind direction is mainly southerly or northerly when fog occurs．Three typical conceptual models of summer fog in the Beijing-Tianjin-Hebei Region are radiation fog under the control of high pressure ridge, advection radiation fog under the control of southwest airflow in front of upper trough, and rain fog under the control of subtropical high pressure．
2022, 48(7):913-924.
DOI: 10.7519/j.issn.1000-0526.2022.032202
Abstract:
The climate comfort index is the basis of the forecast of weather comfort degree and climate suitability assessment for tourism. Various bioclimatic indices have been developed with their own purposes. However, they could not be able to accurately describe human comfort perception to different weather conditions in various climate zones in China. To fill this gap, a new universal and semi-empirical climate comfort indicator (outdoor weather comfort index, OWCI) is proposed based on the previous results on the relationships between meteorological elements and human thermal comfort and the analysis of meteorological element characteristics in different regions of China and questionnaires. The OWCI model consists of five components that describe the impacts of daily average and maximum temperatures, humidity, wind speed and radiation on human comfort perception, respectively. The impact of the temperature on the effects of humidity, wind and sunshine is taken into account. The OWCI allows for more weather elements and interactions between them than the empirical models in use so far, so it could depict its capability of capturing human comfort perception in the daytime. Verification questionnaires and case studies in different climatic regions in China show that the OWCI could reflect the subjective comfort perception of respondents much more accurately under various weather conditions. Therefore, it could be more widely applied in different seasons and climate zones across China wherever the basic meteorological data are available. Furthermore, the data of OWCI are suitable for statistical analysis, which is conducive to spatiotemporal evaluation and assessment of climate change impacts on comfort perception.
The climate comfort index is the basis of the forecast of weather comfort degree and climate suitability assessment for tourism. Various bioclimatic indices have been developed with their own purposes. However, they could not be able to accurately describe human comfort perception to different weather conditions in various climate zones in China. To fill this gap, a new universal and semi-empirical climate comfort indicator (outdoor weather comfort index, OWCI) is proposed based on the previous results on the relationships between meteorological elements and human thermal comfort and the analysis of meteorological element characteristics in different regions of China and questionnaires. The OWCI model consists of five components that describe the impacts of daily average and maximum temperatures, humidity, wind speed and radiation on human comfort perception, respectively. The impact of the temperature on the effects of humidity, wind and sunshine is taken into account. The OWCI allows for more weather elements and interactions between them than the empirical models in use so far, so it could depict its capability of capturing human comfort perception in the daytime. Verification questionnaires and case studies in different climatic regions in China show that the OWCI could reflect the subjective comfort perception of respondents much more accurately under various weather conditions. Therefore, it could be more widely applied in different seasons and climate zones across China wherever the basic meteorological data are available. Furthermore, the data of OWCI are suitable for statistical analysis, which is conducive to spatiotemporal evaluation and assessment of climate change impacts on comfort perception.
2022, 48(7):925-935.
DOI: 10.7519/j.issn.1000-0526.2022.061701
Abstract:
The East Asian winter monsoon and the Siberian high were both stronger than normal during the 2021/2022 winter. Temperature over China was colder than normal in winter, and the overall spatial feature was “warmer in Northern China and colder in Southern China”. Precipitation over China was more than normal, especially in the Qinghai-Tibetan Plateau, Southwest China and South China. The Arctic Oscillation maintained a positive phase for a long time in winter, in favorable for the weak Ural Mountain blocking high. The Okhotsk blocking high was abnormally active, and the center of the positive anomaly at the 500 hPa height field extended westward from the Sea of Okhotsk to Lake Baikal-Lake Balkhash. In addition, the positive phase of the Arctic Oscillation in winter also affected East Asia by an indirect way of the southern Eurasian teleconnection, leading to a stronger Middle East jet stream and a persistently lower height field in Tibetan Plateau. Coordinated with the La Ni〖AKn~D〗a event, the 500 hPa height field over East Asia presented a “higher in the north and lower in the south” pattern, thus temperature over China showed an anomalous distribution of “warmer in the Northern China and colder in Southern China”, and precipitation over Southern China was more than normal. Temperature over China was “warmer in the earlier winter and colder in the later winter”, which was closely related to the intraseasonal variation of the East Asian winter monsoon, which was “weaker in the earlier winter and stronger in the later winter”.
The East Asian winter monsoon and the Siberian high were both stronger than normal during the 2021/2022 winter. Temperature over China was colder than normal in winter, and the overall spatial feature was “warmer in Northern China and colder in Southern China”. Precipitation over China was more than normal, especially in the Qinghai-Tibetan Plateau, Southwest China and South China. The Arctic Oscillation maintained a positive phase for a long time in winter, in favorable for the weak Ural Mountain blocking high. The Okhotsk blocking high was abnormally active, and the center of the positive anomaly at the 500 hPa height field extended westward from the Sea of Okhotsk to Lake Baikal-Lake Balkhash. In addition, the positive phase of the Arctic Oscillation in winter also affected East Asia by an indirect way of the southern Eurasian teleconnection, leading to a stronger Middle East jet stream and a persistently lower height field in Tibetan Plateau. Coordinated with the La Ni〖AKn~D〗a event, the 500 hPa height field over East Asia presented a “higher in the north and lower in the south” pattern, thus temperature over China showed an anomalous distribution of “warmer in the Northern China and colder in Southern China”, and precipitation over Southern China was more than normal. Temperature over China was “warmer in the earlier winter and colder in the later winter”, which was closely related to the intraseasonal variation of the East Asian winter monsoon, which was “weaker in the earlier winter and stronger in the later winter”.
2022, 48(7):936-944.
DOI: 10.7519/j.issn.1000-0526.2022.060801
Abstract:
The main characteristics of the general atmospheric circulation in April 2022 are as follows. There was one polar vortex center in the Northern Hemisphere, weaker than usual. The circulation in middlehigh latitudes showed a threewave pattern, and there was a positive anomaly of the geopotential height over China. The strength of Western Pacific subtropical high was weaker than that in normal years. The monthly mean temperature was 12.4℃, 0.9℃ higher than normal, becoming the fifth highest in records since 1961. The monthly mean precipitation amount was 45.7 mm, 4.8% more than normal, of which the precipitation in the southwest of China was significantly higher than in normal years. Only one cold air process appeared in this month. Large scale of regional rainfall processes occurred twice in China this month, and some regions were attacked by severe thunderstorm and hail disaster. In addition, northern China experienced three sanddust weather events, and the hint of drought was found in the provinces of Henan, Shaanxi, Shanxi and Shandong, developing.
The main characteristics of the general atmospheric circulation in April 2022 are as follows. There was one polar vortex center in the Northern Hemisphere, weaker than usual. The circulation in middlehigh latitudes showed a threewave pattern, and there was a positive anomaly of the geopotential height over China. The strength of Western Pacific subtropical high was weaker than that in normal years. The monthly mean temperature was 12.4℃, 0.9℃ higher than normal, becoming the fifth highest in records since 1961. The monthly mean precipitation amount was 45.7 mm, 4.8% more than normal, of which the precipitation in the southwest of China was significantly higher than in normal years. Only one cold air process appeared in this month. Large scale of regional rainfall processes occurred twice in China this month, and some regions were attacked by severe thunderstorm and hail disaster. In addition, northern China experienced three sanddust weather events, and the hint of drought was found in the provinces of Henan, Shaanxi, Shanxi and Shandong, developing.
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