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Journal of Meteorological Research 2021年第5期35卷 831-843页

作者： Yating XIONG xuejuan ren CMA–NJU Joint Laboratory for Climate Prediction Studies School of Atmospheric SciencesNanjing UniversityNanjing 210023

Atmospheric rivers(ARs),the long and narrow conveyors of intense moisture transport,have a non-negligible impact on hydrometeorological events over the extratropical *** study analyzes the climatology and interannual variability of ARs and their quantitative association with precipitation and precipitation extremes over East Asia(EA)during 1979-2019,based on calculations of not only moisture transport but also moisture flux *** is found that the ARs over EA occur frequently in spring and summer,accounting for 25%-40%of seasonal precipitation and 60%-75%of extreme precipitation over *** in AR frequency are observed over EA during post-El Ni?o summers,meanwhile the AR-related anomalous moisture convergence is found leading to the increase of extreme ***,increased ARs account for 70%-90%of total precipitation anomalies and up to 90%of extreme precipitation anomalies over the middle-lower reaches of the Yangtze River,and the anomalies of moisture flux convergence are caused mainly by changes in horizontal wind convergence rather than moisture advection during the post-El Ni?o summers.

关键词： atmospheric rivers precipitation extreme events water vapor interannual variability

Decadal and Interannual Variability of Persistent Heavy Rainfall Events over the Middle and Lower Reaches of the Yangtze River Valley

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Journal of Meteorological Research 2019年第6期33卷 1031-1043页

作者： Ruan YAO xuejuan ren China Meteorological Administration–Nanjing University Joint Laboratory for Climate Prediction Studies School of Atmospheric SciencesNanjing UniversityNanjing 210023

This study investigates the relationship between the anomalous atmospheric circulation pattern and summertime persistent heavy rainfall(PHR)over the middle and lower reaches of the Yangtze River valley(MLYRV)on the decadal and interannual *** on the gridded daily rainfall data of the US Climate Prediction Center,the PHR events on grid-point and the regional PHR events considering both the area of PHR and regionally averaged rainfall intensity are identified over the MLYRV during the summers of 1979–2017.A PHR index(PHRI)is defined,to describe the variability of summertime PHR event number over the *** PHRI is then divided into the decadal and interannual *** analysis reveals that the decadal PHR events are closely related to anomalous precipitation,intensified vertical motion,and strengthened upper-level divergence over southern China,as well as an anomalous anticyclone over the western Pacific transporting more water vapor from the South China Sea(SCS)to southern *** for the interannual component,the above pattern still co-exists but over a narrow region around the *** choosing the years in which the decadal and interannual components of the PHRI are simultaneously positive(SP)or negative(SN),the features of regional PHR events in SP and SN years are analyzed,*** results show that there are more regional PHR events in SP years with enhanced intensity and larger affected areas compared with those in SN ***,the zonal oscillations of the South Asian high(SAH)and the western Pacific subtropical high(WPSH)during the regional PHR events demonstrate a better regularity in SP years than those in SN years.

关键词： middle and lower reaches of the Yangtze River valley(MLYRV) persistent heavy rainfall(PHR) decadal variability interannual variability

Mean Flow–Storm Track Relationship and Rossby Wave Breaking in Two Types of El-Nino

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Advances in Atmospheric Sciences 2014年第1期31卷 197-210页

作者： LIU Chengji ren xuejuan YANG Xiuqun School of Atmospheric Sciences Nanjing University

The features of large-scale circulation, storm tracks and the dynamical relationship between them were examined by investigating Rossby wave breaking （RWB） processes associated with Eastern Pacific （EP） and Central Pacific （CP） E1-Nifio. During EP E1-Nino, the geopotential height anomaly at 500 hPa （Z500） exhibits a Pacific-North America （PNA） pattern. During CP EI-Nifio, the Z500 anomaly shows a north positive-south negative pattern over the North Pacific. The anomalous distributions of baroclinicity and storm track are consistent with those of upper-level zonal wind for both EP and CP EI-Nino, suggesting impacts of mean flow on storm track variability. Anticyclonic wave breaking （AWB） oczurs less frequently in EP EI-Nino years, while cyclonic wave breaking （CWB） occurs more frequently in CP EI-Nino years over the North Pacific sector. Outside the North Pacific, more CWB events occur over North America during EP Ei-NiNo. When AWB events occur less frequently over the North Pacific during EP EI-Nino, Z500 decreases locally and the zonal wind is strengthened （weakened） to the south （north）. This is because AWB events reflect a monopoie high anomaly at the centroid of breaking events. When CWB events occur more frequently over the North Pacific under CP EI-Nino conditions, and over North America under EP EI-Nino condition, Z500 increases （decreases） to the northeast （southwest）, since CWB events are related to a northeast-southwest dipole Z500 anomaly. The anomalous RWB events act to invigorate and reinforce the circulation anomalies over the North Pacific-North America region linked with the two types of EI-Nino.

关键词： central Pacific EI-Nino eastern Pacific El-Nifio large-scale circulation storm track Rossby wave breaking

Atmospheric eddy anomalies associated with the wintertime North Pacific subtropical front strength and their influences on the seasonal-mean atmosphere

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Science China Earth Sciences 2016年第10期59卷 2022-2036页

作者： WANG LiYing HU HaiBo YANG XunQun ren xuejuan CMA-NJU Joint Laboratory for Climate Prediction Studies Instituted for Climate and Global Change Research School of Atmospheric Science Nanjing University

This study investigates transient eddy activity anomalies in the mid-latitude upper troposphere associated with intensity variability of the wintertime North Pacific subtropical front. Our results show that the meridional gradient of air temperature and baroclinic instability in the mid-latitude atmosphere become stronger as the subtropical front intensifies, and the mid-latitude westerly jet accelerates with barotropic structure. We further divide the mid-latitude atmospheric eddy activities into high-(2–7 days) and low-frequency(10–90 days) eddy activities according to their life periods. We find that, when the oceanic subtropical front intensifies, the high-frequency atmospheric eddy activity in the mid-latitudes strengthens while the low-frequency eddy activity weakens. The stronger high-frequency eddy activity tends to moderate the air temperature gradient and baroclinicity in the mid-latitudes. High-frequency eddy anomalies accelerate the westerly jet on the northern side and downstream of the westerly jet, and enhance the jet with equivalent barotropic structure. In contrast, the weaker low-frequency eddy activity has a negative contribution to zonal wind speed tendency and attenuates the zonal homogenization of the jet. The anomalous thermodynamic forcing of the low-frequency eddy activity helps maintain the meridional gradient of air temperature in the mid-troposphere.

关键词： North Pacific subtropical front Frequency Eddy activity Mid-Latitude Ocean-Atmosphere interaction

Subseasonal Zonal Oscillation of the Western Pacific Subtropical High during Early Summer

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Journal of Meteorological Research 2018年第5期32卷 768-780页

作者： Weina GUAN xuejuan ren Wei SHANG Haibo HU China Meteorological Administration–Nanjing University Joint Laboratory for Climate Prediction Studies School of Atmospheric Sciences Nanjing University

This study examines the features and dynamical processes of subseasonal zonal oscillation of the western Pacific subtropical high （WPSH） during early summer, by performing a multivariate empirical orthogonal function （MV- EOF） analysis on daily winds and a diagnosis on potential vorticity （PV） at 500 hPa for the period 197%2016. The first MV-EOF mode is characterized by an anticyclonic anomaly occupying southeastern China to subtropical west-ern North Pacific regions. It has a period of 10-25 days and represents zonal shift of the WPSH. When the WPSH stretches more westward, the South Asian high （SAH） extends more eastward. Above-normal precipitation is ob- served over the Yangtze-Huaihe River （YHR） basin. Suppressed convection with anomalous descending motion is located over the subtropical western North Pacific. The relative zonal movement of the SAH and the WPSH helps to establish an anomalous local vertical circulation of ascending motion with upper-level divergence over the YHR basin and descending motion with upper-level convergence over the subtropical western Pacific. The above local ver-tical circulation provides a dynamic condition for persistent rainfall over the YHR basin. An enhanced southwest flow over the WPSH＇s western edge transports more moisture to eastem China, providing a necessary water vapor condition for the persistent rainfall over the YHR basin. A potential vorticity diagnosis reveals that anomalous diaba- tic heating is a main source for PV generation. The anomalous cooling over the subtropical western Pacific produces a local negative PV center at 500 hPa. The anomalous heating over the YHR basin generates a local positive PV cen-ter. The above south-north dipolar structure of PV anomaly along with the climatological southerly flow leads to northward advection of negative PV. These two processes are conducive to the WPSH＇s westward extension. The vertical advection process is unfavorable to the westward extension but contributes to the ea

关键词： western Pacific subtropical high subseasonal timescale diabatic heating potential vorticity

Persistent Heavy Rainfall over South China During May–August:Subseasonal Anomalies of Circulation and Sea Surface Temperature

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Acta meteorologica Sinica 2013年第6期27卷 769-787页

作者：洪伟任雪娟 School of Atmospheric Sciences Nanjing University

This study investigates the relationship between subseasonal variations of the circulation and sea surface temperature（SST） over the South China–East Asian coastal region（EACR） in association with the persistent heavy rainfall（PHR） events over South China during May–August through statistical analysis. Based on the intensity threshold and duration criterion of the daily rainfall, a total of 63 May–June（MJ） and 59July–August（JA） PHR events are selected over South China from 1979 to 2011. The lower-level circulation anomalies on subseasonal timescale exhibit an anomalous cyclone over South China and an anomalous anticyclone shaped like a tongue over the South China Sea（SCS） during the PHR events for MJ *** anomalous cyclone over South China in MJ originates from low-value systems in the mid-high latitudes before the rainfall. The anomalous anticyclone over the SCS is due to the westward extension of the western Pacific subtropical high（WPSH） and the southeastward propagation of the anomalous anticyclone from South China before the rainfall. For JA group, the lower-level anomalous circulation pattern is similar to that for MJ over the South China–EACR, but with di？erent features of propagation. The subseasonal anomalous anticyclone is also related to the westward stretch of the WPSH, while the anomalous cyclone is traced back to the weak anomalous cyclone over the Philippine Sea several days before the rainfall *** SST anomaly（SSTA） is observed over the SCS and the Philippine Sea during the MJ PHR events on the subseasonal timescale. It is closely linked with the variation of local anomalous anticyclone. In contrast, negative SSTA occupies the South China coastal region for the JA PHR events, and it is driven by the anomalous cyclone which propagates northwestward from the Philippine Sea. The subseasonal positive（negative） SSTAs are generated via the local processes of above（below）-normal incident solar radiation and below（above）-normal latent heat fl

关键词： persistent heavy rainfall western Pacific subtropical high subseasonal variations of sea surface temperature South China

Subseasonal Variations of Wintertime North Pacific Evaporation,Cold Air Surges and Water Vapor Transport

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Subseasonal Variations of Wintertime North Pacific Evaporati...

A Regional Air-Sea Coupled Model and Its Application over East Asia in the Summer of 2000

第35届中国气象学会年会

作者： ren xuejuan YANG Xiu-Qun HU Haibo School of Atmospheric Sciences Nanjing University

This study addresses subseasonal variations of oceanic evaporation（E） over the North Pacific during winter,and the connection with the cold air surges（CAS） and atmospheric water vapor transport using the OAFlux and ERA-Interim daily *** performing an empirical orthogonal function（EOF） analysis,two dominant modes of subseasonal evaporation anomaly（E?） are identified:a zonally wave-train like pattern（EOF1）,and an east positive–west negative dipolar pattern（EOF2） in the midlatitude *** analyses yield the following conclusions.（1） The Siberian high（SH）-related CAS has a crucial role in generation of the EOF1 mode of E?.When the dry and cold airmass passes the warm Kuroshio current and its extension（KOE） region,the increased air–sea temperature and moisture differences and intensified wind speed lead to the above-normal oceanic E,and vice versa.（2） The Aleutian low（AL）-related CAS contributes to the EOF2 mode of E?.The intensified AL transports dramatically colder and drier airmass toward the KOE region,and slightly warmer and wetter one toward the west coast of North America,leading to the east positive–west negative structure of E? in the midlatitude basin.（3）A quasi-linear relationship exists between E? and divergent water vapor transport anomalies over the KOE ***（negative） E? is generally accompanied by anomalous vapor source（sink）.（4） The divergent water vapor transport anomalies associated with the two EOFs are preliminarily decided by their individual lower-level wind fields anomalies,and secondly by the meridional inhomogeneity of subseasonal specific humidity *** effects on precipitation over the pan-North Pacific region are also discussed.

关键词： oceanic evaporation cold air surges atmospheric water vapor transport subseasonal time scale

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Advances in Atmospheric Sciences 2010年第3期27卷 583-593页

作者：房永杰张耀存汤剑平任雪娟 School of Atmospheric Sciences Nanjing University

A regional air-sea coupled model, comprising the Regional Integrated Environment Model System （RIEMS） and the Princeton Ocean Model （POM） was developed to simulate summer climate features over East Asia in 2000. The sensitivity of the model＇s behavior to the coupling time interval （CTI）, the causes of the sea surface temperature （SST） biases, and the role of air-sea interaction in the simulation of precipitation over China are investigated. Results show that the coupled model can basically produce the spatial pattern of SST, precipitation, and surface air temperature （SAT） with five different CTIs respectively. Also, using a CTI of 3, 6 or 12 hours tended to produce more successful simulations than if using 1 and 24 hours. Further analysis indicates that both a higher and lower coupling frequency result in larger model biases in air-sea heat flux exchanges, which might be responsible for the sensitivity of the coupled model＇s behavior to the CTI. Sensitivity experiments indicate that SST biases between the coupled and uncoupled POM occurring over the China coastal waters were due to the mismatch of the surface heat fluxes produced by the RIEMS with those required by the POM. In the coupled run, the air-sea feedbacks reduced the biases in surface heat fluxes, compared with the uncoupled RIEMS, consequently resulted in changes in thermal contrast over land and sea and led to a precipitation increase over South China and a decrease over North China. These results agree well observations in the summer of 2000.

关键词： regional air-sea coupled model coupling time interval air-sea interactions East Asian climate

Subseasonal Zonal Oscillation of Western Pacific Subtropical High during Early Summer

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Subseasonal Zonal Oscillation of Western Pacific Subtropical...

华北夏季大气水汽输送特征及其与夏季旱涝的关系

第35届中国气象学会年会

作者： ren xuejuan GUAN Weina SHANG Wei HU Haibo School of Atmospheric Sciences Nanjing University

This study examines the features and dynamical processes of subseasonal zonal oscillation of the western Pacific subtropical high(WPSH)during early summer,by performing a multivariate empirical orthogonal function(MV-EOF)analysis on daily winds and a diagnosis on potential vorticity(PV)at 500 h Pa for the period *** first MV-EOF mode is characterized by an anticyclonic anomaly occupying southeastern China-subtropical western North Pacific *** has a period of 10–25 days and represents zonal shift of the *** the WPSH stretches more westward,the South Asian high(SAH)extends more *** above-normal precipitation is observed over the Yangtze-Huaihe River(YHR)basin.A suppressed convection with an anomalous descending motion is located over the subtropical western North Pacific(Fig.1).The relative zonal movement of the SAH and the WPSH contributes to establish an anomalously local vertical circulation of ascending motion with upper level divergence over the YHR basin,and descending motion with upper level convergence over the subtropical western *** local vertical circulation provides a dynamic condition for persistent rainfall over the YHR *** enhanced southwest flow over the WPSH's western edge transports more moisture to eastern China,providing a necessary vapor condition for the persistent rainfall over the YHR basin.A potential vorticity diagnosis reveals that anomalous diabatic heating is a main source of PV *** anomalous cooling over the subtropical western Pacific produces a locally negative PV center at 500 h *** anomalous heating over the YHR basin generates a locally positive PV *** above south-north dipolar structure of PV anomaly along with the climatological southerly flow leads to northward advection of negative *** two processes are conducive to the WPSH's westward *** vertical advection process is unfavorable to the westward extension but contributes to the eastward retreat of

关键词： western Pacific subtropical high subseasonal time-scale diabatic heating potential vorticity

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气象科学 2008年第5期28卷 508-514页

作者：谢坤任雪娟南京大学灾害性天气气候研究所南京210093

本文利用ECMWF再分析资料ERA40和中国160站的降水资料,分析了我国华北地区1958年—2002年夏季的大气水汽含量和水汽输送的基本气候特征,研究了华北夏季旱涝年的大气水汽含量和水汽输送异常情况,最后利用线性回归的方法探讨了该地区大气... 详细信息

本文利用ECMWF再分析资料ERA40和中国160站的降水资料,分析了我国华北地区1958年—2002年夏季的大气水汽含量和水汽输送的基本气候特征,研究了华北夏季旱涝年的大气水汽含量和水汽输送异常情况,最后利用线性回归的方法探讨了该地区大气水汽含量和水汽输送的变化趋势。结果表明:华北地区夏季降水的大气水汽来源主要有3支:来自孟加拉湾的水汽、来自我国南海和西太平洋的水汽以及中高纬西风带的水汽输送。华北地区对流层低层以经向水汽输送通量为主,到了中高层则以纬向输送通量为主;与华北地区夏季旱涝密切相关的异常水汽输送主要是南海和西太平洋以及西风带水汽输送异常,华北地区南边界水汽输入异常和东边界水汽输出异常是造成华北夏季旱涝年水汽收支异常的主要原因;近半个世纪以来,伴随着华北干旱化的加剧,华北地区南边界输入的大气水汽呈现显著的减少趋势。

关键词：大气水汽输送华北夏季旱涝线性趋势