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characteristics of Two General circulation Patterns During Floods over the Changjiang-Huaihe River Valley

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Acta meteorologica Sinica 2007年第3期21卷 366-375页

作者：丁淑秋林学椿 State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing 100081 National Climate Center Beijing 100081

characteristics of the atmospheric general circulation during the catastrophic floods over the ChangjiangHuaihe River Valley （CHRV） are investigated. There are two precipitation patterns over China in the CHRV flood years： the CHRV flood-whole country-wet （P1） pattern and the CHRV flood-south （north） side-dry （P2） pattern. The circulation analysis results show that there are obvious differences between the NH 500- hPa geopotential height fields of P1 and P2 precipitation patterns. The establishment of East Asia-Atlantic （EAA） correlation chain （the South China Sea （SCS） high-the Meiyu trough-the Okhotsk Sea high over East Asia） is a critical condition for excessive summer precipitation over the CHRV, while the European blocking high plays an important role in determining the precipitation pattern over China in the CHRV flood years. Besides, the relation between the EAA correlation chain and the sea surface temperature anomaly （SSTA） in the North Pacific is also studied.

关键词： flood circulation characteristics blocking high sea surface temperature

circulations and Thermodynamic characteristics of Different Patterns of Rainstorm Processes in the Eastern Foot of Helan Mountain

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Journal of Tropical Meteorology 2022年第3期28卷 343-363页

作者：陈豫英李建平张肃诏苏洋杨银张一星姚姗姗 Key Laboratory for Meteorological Disaster Monitoring and Early Warning and Risk Management of Characteristic Agriculture in Arid Regions CMAYinchuan 750002 China Ningxia Key Laboratory of Meteorological Disaster Prevention and Mitigation Yinchuan 750002 China Ningxia Meteorological Observatory Yinchuan 750002 China Key Laboratory of Physical Oceanography Institute for Advanced Ocean StudiesQingdao National Laboratory for Marine Science and TechnologyOcean University of ChinaQingdaoShandong 266100 China

Based on the observational hourly precipitation data and the European Centre for Medium-Range Weather Forecasts(ECMWF)Reanalysis 5(ERA5)products from 2006 to 2020,22 rainstorm processes in the eastern foot of Helan Mountain are objectively classified by using the hierarchical clustering method,and the circulation characteristics of different patterns are comparatively analyzed in this study.The results show that the occurrences of rainstorm processes in the eastern foot of Helan Mountain are most closely related to three circulation patterns.PatternsⅠandⅢmainly occur in July and August,with similar zonal circulations in synoptic backgrounds.Specifically,the South Asia high and the western Pacific subtropical high are stronger and more northward than those in normal years.The frontal systems in westerlies are inactive,while the water vapor from the ocean surface in the south is mainly transported to the rainstorm area by the southerly jet stream at 700 h Pa.The dynamic lifting anomalies are relatively weak,the instability of atmospheric stratification is anomalously strong,and thus the localized severe convective rainstorm is more significant.Comparatively,rainstorm processes of patternⅠare accompanied by stronger and deeper ascending motions,and the warm-sector rainstorm is more extreme.PatternⅢshows a stronger and deeper convective instability,accompanied by larger low-level moisture.Rainstorm processes of patternⅡmainly occur in early summer and early autumn,presenting a meridional circulation pattern of high in the east and low in the west in terms of geopotential height.Moreover,the two low-level jets transporting the water vapor northward from the ocean on the east of China encounter with the frontal systems in westerlies,which makes the ascending motion in patternⅡanomalously strong and deep.The relatively weak instability of atmospheric stratification causes weak convection and long-lasting precipitation formed by the confluence of cold air and warm air.This study may help improve rainstorm forecasting in

关键词： eastern foot of Helan Mountain rainstorm hierarchical clustering objective classification circulation characteristics

Inhomogeneity characteristics of snow in Northeast China

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Journal of Geographical Sciences 2011年第4期21卷 621-633页

作者： WANG Ji ZOU Liyao ZHAO Chunyu LOU Dejun Beijing Regional Climate Center Beijing 100089 China China Meteorological Administration Training Centre Beijing 100081 China Liaoning Climate Center Shenyang 110014 China Qiqihar Meteorological Bureau Qiqihar 161006 Heilongjiang China

Based on 1961-2005 observed winter precipitation data in Northeast China, the temporal and spatial variations of snow concentration degree （SCD） and snow concentration period （SCP）, together with the circulation characteristics when there is a higher SCD, are computed and analyzed. Results show that SCD in Northeast China presents a yearly rising tendency and SCP decreases obviously. In terms of decadal variation, there is a 12-year periodic variation in PCP, and since the mid-1970s there has been an 8-year short periodic variation. As to spatial variation, SCD in winter of Northeast China has increased gradually from the eastern part to the western, and the minimum value of SCD occurs in the east of Jilin Province, while the high value center is observed in the central part of the province. For the whole Northeast China, the variation tendencies are consistent in the eastern and central parts, where SCD presents a rising tendency and SCP shows a decreasing tendency. SCD in the southwestern and northern parts has a slight rising tendency, with SCD in the southwestern part having the slightest increasing tendency, and SCP in the northern part showing the slightest decreasing tendency. When a high SCD value is observed, the whole region is controlled by the East Asian deep trough at 500 hPa, and the trough becomes deeper in the western part, while a high pressure, which is easily formed and intensified in the eastern part, makes the East Asian deep trough move eastward slowly. Upper-level jet stream and low-level jet stream co-exist, and the former is stronger and takes more of a southwestward position than the latter. The high value zone of water vapor transport over the Pacific is intensified obviously, and the extent also increases. Northeast China is influenced by the water vapor transported to the northwest along the north of the high value center.

关键词： Northeast China snow concentration degree snow concentration period circulation characteristics

Analysis on the Long-Lasting Freezing Rain and Snowstorm Event at the Beginning of 2008

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Acta meteorologica Sinica 2010年第3期24卷 380-396页

作者：杨贵名孔期毛冬艳张芳华康志明宗志平 National Meteorological Center China Meteorological Administration

In this paper,main characteristics of the long-lasting freezing rain and snowstorm event in southern China at the beginning of 2008,features of the related atmospheric circulation and the causes thereof are analyzed.During the event,patterns of the atmospheric circulation stayed stable;the polar vortex located in the northern part of the Eastern Hemisphere was strong with little movement;the cold front from the polar region and the active warm air mass from the tropical ocean confronted each other for a long time;the blocking high to the west of Baikal remained strong and steady;the trough over central and western Asia maintained its position for quite long with a group of little troughs splitting from it frequently;the dominant wind at 700 hPa was southwesterly while shears and vortexes at 850 hPa developed continually,providing the necessary low-level convergence for subsequent precipitation.Meanwhile,in the mid troposphere,eddies were generated over the Tibetan Plateau and positive vorticity disturbances in the Sichuan Basin propagated eastward to the coastal regions of eastern China.The western Pacific subtropical high was intensive with westward and northward migrations.The subtropical frontal zone was puissant and the north-south temperature gradient was large.Quasi-stationary fronts over South China and the Yunnan-Guizhou Plateau remained stable.Warm air masses over the tropical ocean were active,so was the trough in the southern branch of the westerlies over the Bay of Bengal.There were four episodes associated with this event.The first one was featured with the interaction of strong cold and warm air,while the other three with the quasi-stationary fronts over South China and the Yunnan-Guizhou Plateau as well as vigorous penetration of cold air from the north.The existence of the inversion layer and the thick melting layer were one of the main reasons for the long-lasting freezing rains.The main reason for the snowstorms was that the positive vorticity over the Sichuan Basin propagated eastward to the co

关键词： freezing rain and snowstorm circulation characteristics cold and warm air inversion western Pacific subtropical high

CHARACTERIZATION AND CAUSAL ANALYSIS OF TEMPORAL AND SPATIAL VARIATION IN DRY-WET CONDITIONS IN AUTUMN IN SOUTHWEST CHINA

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Journal of Tropical Meteorology 2015年第1期21卷 55-66页

作者：李栋梁徐栋夫王慧曲巧娜赵晓萌 Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters/Key Laboratory of Meteorological Disaster of Ministry of Education/School of Atmospheric Science NUIST Meteorological Bureau of Chengdu Shandong Province Institute of Meteorological Science Climate Center of Shaanxi Province

Based on the daily precipitation and temperature data of 97 stations in Southwest China(SW China) from1960 to 2009, a dry-wet index is calculated. The spatiotemporal variation characteristics of dry-wet conditions,precipitation and temperature are studied. Then the abnormal atmospheric circulation characteristics are discussed using reanalysis data. The results show that SW China has exhibited an overall trend of autumnal drought since the late1980 s, and this drought trend became more significant early in the 2000 s, especially in the eastern SW China. Autumnal dry-wet variation in southwestern China showed two major modes: consistent change across the entire region and opposing changes in the eastern and western regions. The spatial distribution of dry-wet anomalies was more significantly affected by precipitation, while temporal variation in dry-wet conditions was more strongly influenced by temperature. The former mode is affected by the anomalies of the precedent SST near the Western Pacific Warm Pool,the Western Pacific Subtropical High, the East Asian Trough and the South Trough. The latter mode is related to the wind anomalies in the eastern SW China and the vertical movement in the western and eastern SW China. These are the main influencing factors for the autumn dry-wet variation in SW China, which are of great significance to the prediction of drought.

关键词： dry-wet characteristics EOF analysis Southwest China circulation characteristics SST

Climate characteristics of High Temperature Weather in Xi'an City in Recent 59 Years

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Meteorological and Environmental Research 2011年第9期2卷 43-46页

作者： MENG Xiao-rong YANG Xiao-chun Qu Jing JIN Li-na Xi’an Meteorological Service Xi’an 710016China

[Objective] The aim was to study the characteristics of high temperature in Xi’an City over the last 59 years. [Method] By dint of daily highest temperature in the Xi’an observatory, the climate characteristics of high temperature at different intensities and the high attitude circulation were studied by statistical method. [Result] Over the last 59 years, there were 22.95 high temperature days each year on average in Xi’an City, which occurred from the last ten days of April to the first ten days of September. Most high temperature days occurred in the last ten days of July, followed by that in the last ten days of June. There were two peak values in the last ten days of June and last ten days of July when temperature ≥38.0 ℃. For the hottest day, it occurred most in the last twenty days of June, followed by July, and rarely in August. The interannual changes in the high temperature day, hot day and hottest day showed one-little and one-much trend. It was much from 1950s to 1960s, from 1970s to 1980s and then grew more after 1990s. The annual extreme highest temperature took place in the last twenty days of June, and then in the last ten days of July. Its interannual changes showed high-low-high trend. The high temperature appeared most often in July and also lasted for the longest duration. The hot day lasted for two days. The hottest days of ≥40.0 ℃ were very rare. The circulation of high temperature generally fell into one of four categories: continental high pressure controlling type, subtropical high controlling type, strip high pressure controlling type and northwest airstream controlling type. [Conclusion] The study provided references for the forecast and pre-warning of high temperature.

关键词： High temperature Changes characteristics circulation characteristics Xi'an City, China

THE ALTERNATE-SEASONAL CORRELATION OF LONG—RANGE WEATHER PROCESS

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Acta meteorologica Sinica 1992年第4期6卷 462-469页

作者： Lin Xuechun Zhang Ruixue Chinese Academy of Meteorological Sciences,Beijing 100081

In this paper,the correlation of meteorological elements at an interval of 5—7 months,i.e.,the alternate-seasonal correlation,is thoroughly analyzed.The results show that the alternate-seasonal correlation is an important phenome- non in the long-range weather process,and it has a significant latitude effect and seasonal variations.Furthermore,the relation between this phenomenon and SST in the North Pacific is discussed.

关键词： alternate-seasonal correlation circulation characteristics Pacific temperature index(PTI)

Analysis of a Rare Continuous Rainy Process in Midsummer

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Meteorological and Environmental Research 2011年第8期2卷 26-29页

作者： MA Ling CHEN Ling-ling WANG Xiang Bengbu Meteorological Bureau in Anhui Province Bengbu 233000China

[Objective] The research aimed to analyze a rare low temperature and rainy weather process which happened in Anhui Province from July 22 to August 14,2009.[Method] Based on the data of conventional observation,NCEP analysis field and automatic station,a rare low temperature and rainy weather process which occurred in Anhui Province from July 22 to August 14,2009 was analyzed.The formation reason of continuous rainy process in midsummer was discussed.The circulation characteristics and influence systems of continuous rainy process were revealed.On the base,the influences of configuration of circulation fields and difference of physical quantity fields at high and low layers on range and intensity of precipitation were analyzed.[Result] According to the circulation situation and influence system,the continuous rainy process could be divided into four stages:July 22-24,from July 27 to August 1,August 4-8 and August 9-14.Moreover,it was respectively affected by northeast low vortex,cold and warm air,high-level low trough,typhoon and periphery of subtropical high at four stages.The maintenance of big specific humidity zone provided sufficient water vapor condition for the continuous rainy weather.The rainstorm appeared in dense zone of specific humidity line,where the specific humidity >13 g/kg in the humidity front zone.A temperature trough maintained at 850 hPa.The cold air which continued to diffuse and go south was main reason of the abnormally low temperature during the continuous rainy period.Moreover,it provided ascending motion condition for precipitation maintenance.[Conclusion] The research provided references for actual forecast of continuous rainy weather.

关键词： Continuous rainy weather Midsummer circulation characteristics Physical quantity field Process analysis China

中国东北地区低温冷害研究进展与展望(英文)

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Meteorological and Environmental Research 2010年第11期1卷 85-91,96页

作者：郝天依王式功尚可政李璟鑫兰州大学大气科学学院甘肃省干旱气候变化与减灾重点实验室甘肃兰州730000

Focused on the major agro-meteorological disaster in northeast China area-low temperature chilling injury,the research progresses of low temperature chilling injury in northeast China were reviewed systematically.The basic concepts which included the connotation and extension of chilling damage,the circulation characteristics and effect factors which formed summer low temperature in northeast China,the prediction,forecast and defense of low temperature chilling injury were summarized and done the outlook.

关键词： Northeast China low temperature chilling injury circulation characteristics Effect factors Prediction Defense China