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Gravity Wave Activity and Stratosphere-Troposphere Exchange During Typhoon Molave(2020)
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作者 HUANG Dong WAN Ling-feng +3 位作者 WAN Yi-shun CHANG Shu-jie MA Xin ZHAO Kai-jing 《Journal of Tropical Meteorology》 SCIE 2024年第3期306-326,共21页
To investigate the stratosphere-troposphere exchange(STE)process induced by the gravity waves(GWs)caused by Typhoon Molave(2020)in the upper troposphere and lower stratosphere,we analyzed the ERA5 reanalysis data prov... To investigate the stratosphere-troposphere exchange(STE)process induced by the gravity waves(GWs)caused by Typhoon Molave(2020)in the upper troposphere and lower stratosphere,we analyzed the ERA5 reanalysis data provided by the European Centre for Medium-Range Weather Forecasts and the CMA Tropical Cyclone Best Track Dataset.We also adopted the mesoscale forecast model Weather Research and Forecasting model V4.3 for numerical simulation.Most of the previous studies were about typhoon-induced STE and typhoon-induced GWs,while our research focused on the STE caused by typhoon-induced gravity waves.Our analysis shows that most of the time,the gravity wave signal of Typhoon Molave appeared below the tropopause.It was stronger on the east side of the typhoon center(10°-20°N,110°-120°E)than on the west side,suggesting an eastward tilted structure with height increase.When the GWs in the upper troposphere and lower stratosphere region on the west side of the typhoon center broke up,it produced strong turbulence,resulting in stratosphere-troposphere exchange.At this time,the average potential vorticity vertical flux increased with the average ozone mass mixing ratio.The gravity wave events and STE process simulated by the WRF model were basically consistent with the results of ERA5 reanalysis data,but the time of gravity wave breaking was different.This study indicates that after the breaking of the GWs induced by typhoons,turbulent mixing will also be generated,and thus the STE. 展开更多
关键词 gravity wave TYPHOON stratosphere-troposphere exchange STE upper troposphere and lower stratosphere UTLS
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DISTRIBUTION OF AEROSOL EXTINCTION IN THE LOWER TROPOSPHERE BY MICRO-PULSE LIDAR OBSERVATION 被引量:1
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作者 吴永华 胡欢陵 周军 《Acta meteorologica Sinica》 SCIE 2000年第4期503-508,共6页
The profiles of aerosol extinction coefficients are investigated by micro-pulse lidar(MPL) combined with the meteorological data in the lower troposphere at Meteorological Research Institute(MRI).Japan.Larger extincti... The profiles of aerosol extinction coefficients are investigated by micro-pulse lidar(MPL) combined with the meteorological data in the lower troposphere at Meteorological Research Institute(MRI).Japan.Larger extinction values of aerosol are demonstrated in the nocturnal stable air layer with larger Richardson number,and light wind velocities are favorable for aerosol concentrating in the planetary boundary layer(PBL).But aerosol extinction coefficients show larger values over the altitudes of 2.0 to 5.0km where correspond to higher relative humidity (RH).The tops of PBL identified by the aerosol extinction profiles almost agree with ones by radiosonde data.The diurnal variations of aerosol extinction profiles are clearly displayed, intensive aerosol layers usually are formed over the period of mid-morning to 1400 Loeal Time (LT).then elapse in the cloudless late afternoon and nighttime.Thermal eonvection or turbulent transport from the surfaee probably dominates these temporal and spatial changes of aerosol distribution. 展开更多
关键词 AEROSOL micro-puse lidar(MPL) RADIOSONDE lower troposphere
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Study on Horizontal Relative Diffusion in theTroposphere and Lower Stratosphere 被引量:1
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作者 郑毅 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2000年第1期93-102,共10页
The behaviour of relative diffusion theory and Gifford’s random-force theory for long-range atmospheric diffusion is examined. When a puff scale is smaller than the Lagrangian length scale, √2KTL, an accelerative re... The behaviour of relative diffusion theory and Gifford’s random-force theory for long-range atmospheric diffusion is examined. When a puff scale is smaller than the Lagrangian length scale, √2KTL, an accelerative relative diffusion region exists, i.e., σy∝ t 3/2. While the puff diffusion enters a two-dimensional turbulence region, in which the diffusion scale is larger than 500 km, or time scale is larger than 1 day, divergence and convergence are main cause of horizontal diffusion. Between the two above-mentioned regimes, diffusion deviation is given by σy = √2KT. The large-scale horizontal relative diffusion parameters were obtained by analyzing the data of radioactive cloud width collected in air nuclear tests. Key words Tropospheric and lower stratospheric diffusion - Relative diffusion - Large scale turbulence - Nuclear explosion clouds This work is sponsored by the National Natural Science Foundation of China under Grant No. 49505064.The author would like to thank Prof. Chen Jiayi Department of Geophysics of Peking University and Dr. Cai Xiaoming School of Geography and Environmental Sciences of Birmingham University for their helpful discussions. 展开更多
关键词 Tropospheric and lower stratospheric diffusion Relative diffusion Large scale turbulence Nuclear explosion clouds
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Variation of Zonal Winds in the Upper Troposphere and Lower Stratosphere in Association with Deficient and Excess Indian Summer Monsoon Scenario 被引量:1
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作者 Vazhathottathil Madhu 《Atmospheric and Climate Sciences》 2014年第4期685-695,共11页
The Indian summer monsoon is one of the most dominant tropical circulation systems in the general circulation of the atmosphere. The country receives more than 80% of the annual rainfall during a short span of four mo... The Indian summer monsoon is one of the most dominant tropical circulation systems in the general circulation of the atmosphere. The country receives more than 80% of the annual rainfall during a short span of four months (June to September) of the southwest monsoon season. Variability in the quantum of rainfall during the monsoon season has profound impacts on water resources, power generation, agriculture, economics and ecosystems in the country. The inter annual variability of Indian Summer Monsoon Rainfall (ISMR) depends on atmospheric and oceanic conditions prevailed during the season. In this study we have made an attempt to understand the variation of the of zonal winds in the tropical Upper Troposphere and Lower Stratosphere (UT/LS) region during deficient and Excess rainfall years of Indian summer monsoon and its relation to Indian Summer Monsoon Rainfall (ISMR). It is found that in the equatorial Upper Troposphere zonal winds have westerly anomalies during deficient rainfall year’s and easterly anomaly during excess rainfall years of Indian summer monsoon and opposite zonal wind anomaly is noted in the equatorial Lower Stratosphere during the deficient and excess rainfall years of Indian summer monsoon. It is also found that the June to September upper troposphere zonal winds averaged between 15°N and 15°S latitudes have a long-term trend during 1960 to 1998. Over this period the tropical easterlies and the tropical jet stream have weakened with time. 展开更多
关键词 INDIAN Summer MONSOON Upper troposphere/lower STRATOSPHERE ZONAL Winds
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Features of Ozone Mini-Hole Events over the Tibetan Plateau 被引量:10
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作者 卞建春 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2009年第2期305-311,共7页
Based on TOMS total ozone data and SCIAMACHY ozone profile data, climatology of the ozone minihole events over the Tibetan Plateau and ozone vertical structure variations during an ozone mini-hole event in December 20... Based on TOMS total ozone data and SCIAMACHY ozone profile data, climatology of the ozone minihole events over the Tibetan Plateau and ozone vertical structure variations during an ozone mini-hole event in December 2003 are analyzed. The analyses show that before 1990 ozone mini-hole events only occurred in November-December of 1987 but that the number of events increases after 1990. These events only occur from October through February, with maximum occurrence frequency in December. During the event in December 2003, the decrease in total ozone of over 20% is mainly caused by the ozone loss in the upper troposphere and lower stratosphere region due to the horizontal transport of low ozone from the lower latitude subtropics and the uplift of low ozone from the lower troposphere over the Tibetan Plateau. 展开更多
关键词 ozone mini-hole Tibetan Plateau subtropical jet upper troposphere and lower stratosphere
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Role of a Meso-γ Vortex in Meiyu Torrential Rainfall over the Hangzhou Bay,China:An Observational Study 被引量:2
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作者 翟国庆 张红蕾 +3 位作者 沈杭锋 朱佩君 苏涛 李小凡 《Journal of Meteorological Research》 SCIE CSCD 2015年第6期966-980,共15页
A mesoscale torrential rainfall event that occurred over eastern China in June 2013 is analyzed by using observational data.The results show that a mesoscale convergence line and a weak convective cloud line formed ov... A mesoscale torrential rainfall event that occurred over eastern China in June 2013 is analyzed by using observational data.The results show that a mesoscale convergence line and a weak convective cloud line formed over the northern part of the Hangzhou Bay during the onset of the torrential rainfall event.A meso-vortex appeared over the confluence point of northeasterly flow associated with the Yellow-Sea high,easterly flow from rainfall area,and southeasterly flow from the Hangzhou Bay.The meso-vortex with a horizontal scale of 10-20 km lasted for about 1 h for stable surface circulations.The analysis of radar retrieval reveals that the meso-vortex in the boundary layer occurred at the south of strong radar echo.The formation of the meso-vortex turned to enhance convergence and cyclonic vorticity in the lower troposphere,which strengthened updrafts that are tilted into convective clouds and caused torrential rainfall.Thus,the occurrence of the meso-vortex in boundary layer is one of the mechanisms that are responsible for the enhancement of convective development. 展开更多
关键词 torrential rainfall triggering mechanism mesoscale analysis mesoscale disturbance vortex lower tropospheric convergence line
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Regional applicability of seven meteorological drought indices in China 被引量:23
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作者 YANG Qing LI MingXing +1 位作者 ZHENG ZiYan MA ZhuGuo 《Science China Earth Sciences》 SCIE EI CAS CSCD 2017年第4期745-760,共16页
The definition of a drought index is the foundation of drought research.However,because of the complexity of drought,there is no a unified drought index appropriate for different drought types and objects at the same ... The definition of a drought index is the foundation of drought research.However,because of the complexity of drought,there is no a unified drought index appropriate for different drought types and objects at the same time.Therefore,it is crucial to determine the regional applicability of various drought indices.Using terrestrial water storage obtained from the Gravity Recovery And Climate Experiment,and the observed soil moisture and streamflow in China,we evaluated the regional applicability of seven meteorological drought indices:the Palmer Drought Severity Index(PDSI),modified PDSI(PDSI_CN) based on observations in China,self-calibrating PDSI(scPDSI),Surface Wetness Index(SWI),Standardized Precipitation Index(SPI),Standardized Precipitation Evapotranspiration Index(SPEI),and soil moisture simulations conducted using the community land model driven by observed atmospheric forcing(CLM3.5/ObsFC).The results showed that the scPDSI is most appropriate for China.However,it should be noted that the scPDSI reduces the value range slightly compared with the PDSI and PDSI_CN;thus,the classification of dry and wet conditions should be adjusted accordingly.Some problems might exist when using the PDSI and PDSI_CN in humid and arid areas because of the unsuitability of empiricalparameters.The SPI and SPEI are more appropriate for humid areas than arid and semiarid areas.This is because contributions of temperature variation to drought are neglected in the SPI,but overestimated in the SPEI,when potential evapotranspiration is estimated by the Thornthwaite method in these areas.Consequently,the SPI and SPEI tend to induce wetter and drier results,respectively.The CLM3.5/ObsFC is suitable for China before 2000,but not for arid and semiarid areas after 2000.Consistent with other drought indices,the SWI shows similar interannual and decadal change characteristics in detecting annual dry/wet variations.Although the long-term trends of drought areas in China detected by these seven drought indices during 1961-2013 are consistent,obvious differences exist among the values of drought areas,which might be attributable to the definitions of the drought indices in addition to climatic change. 展开更多
关键词 Surface sensible heating Tibetan-Iranian Plateau coupling system(TIPS) Water vapor convergence Upper troposphere and lower stratosphere circulation Cooling center at tropopause
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