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POSSIBLE INFLUENCES OF THE TROPICAL INDIAN OCEAN DIPOLE ON THE EASTWARD PROPAGATION OF MJO

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Journal of Tropical Meteorology 2014年第2期20卷 173-180页

作者：袁媛杨辉李崇银 National Climate Center Laboratory for Climate Studies China Meteorological Administration lasg Institute of Atmospheric Physics Chinese Academy of Sciences Institute of Meteorology PLA University of Science and Technology

Based on multiple datasets, correlation and composite analyses, and case studies, this paper investigated possible influences of the Indian Ocean dipole(IOD) mode on the eastward propagation of intraseasonal oscillation in the tropical atmosphere. The results showed that(1. the 30-60 day outgoing longwave radiation anomalies in the southeastern Indian Ocean and the 30-60 day 850-hPa zonal wind anomalies over the equatorial central Indian Ocean were significantly correlated with the IOD index;(2) during positive IOD years, the anomalously cold water in the southeastern Indian Ocean and the 850-hPa anomalous easterlies over the equatorial central Indian Ocean might act as barriers to the continuously eastward propagation of the intraseasonal convection, which interrupts the Madden-Julian oscillation(MJO) propagation in the eastern equatorial Indian Ocean and western Pacific; and(3) during negative IOD years, the anomalously warm water in the southeastern Indian Ocean and the low-level westerly anomalies over the equatorial central Indian Ocean favor the eastward movement of MJO.

关键词： IOD statistical analyses MJO eastward propagation

Relations of Water Vapor Transport from Indian Monsoon with That over East Asia and the Summer Rainfall in China

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Advances in Atmospheric Sciences 2001年第5期18卷 1005-1017页

作者：张人禾 lasg Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China

A diagnostic study is made to investigate the relationship between water vapor transport from Indian monsoon and that over East Asia in Northern summer. It is found that water vapor transport from Indian monsoon is inverse to that over East Asia. More (less) Indian monsoon water vapor transport corresponds to less (more) water vapor transport over East Asia and less (more) rainfall in the middle and lower reaches of the Yangtze River valley. The Indian summer monsoon water vapor transport is closely related to the intensity of the western Pacific subtropical high in its southwestern part. The stronger (weaker) the Indian summer monsoon water vapor transport, the weaker (stronger) the western Pacific subtropical high in its southwestern part, which leads to less (more) water vapor transport to East Asia, and thus less (more) rainfall in the middle and lower reaches of the Yangtze River valley. Analysis of the out-going longwave radiation anomalies suggests that the convective heating anomalies over the Indian Ocean may have significant impact not only on the Indian monsoon, but also on the East Asian monsoon.

关键词： water vapor transport Indian monsoon East Asian monsoon

Two interannual variability modes of the Northwestern Pacific Subtropical Anticyclone in boreal summer

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Science China Earth Sciences 2013年第7期56卷 1254-1265页

作者： HE Chao ZHOU TianJun ZOU LiWei ZHANG LiXia The State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (lasg) Institute of Atmospheric Physics Chinese Academy of Sciences Graduate University of Chinese Academy of Sciences

Using the reanalysis data and 20th century simulation of coupled model FGOALS_gl developed by lasg/IAP, we identified two distinct interannual modes of Northwestern Pacific Subtropical Anticyclone （NWPAC） by performing Empirical Orthogonal Function （EOF） analysis on 850 hPa wind field over the northwestern Pacific in summer. Based on the associated anoma- lous equatorial zonal wind, these two modes are termed as ＂Equatorial Easterly related Mode＂（EEM） and ＂Equatorial Westerly related Mode＂（EWM）, respectively. The formation mechanisms of these two modes are similar, whereas the maintenance mechanisms, dominant periods, and the relationships with ENSO are different. The EEM is associated with E1.Nifio decaying phase, with the anomalous anticyclone established in the preceding winter and persisted into summer through local positive air-sea feedback. By enhancing equatorial upwelling of subsurface cold water, EEM favors the transition of ENSO from E1.Nifio to La Nifia. The EWM is accompanied by the E1.Nifio events with long persistence, with the anomalous anticyclone formed in spring and strengthened in summer due to the warm Sea Surface Temperature anomalies （SSTA） forcing from the equatorial central-eastern Pacific. The model well reproduces the spatial patterns of these two modes, but fails to simulate the percentage variance accounted for by the two modes. In the NCEP reanalysis （model result）, EEM （EWM） appears as the first mode, which accounts for 35.6% （68.2%） of the total variance.

关键词： Northwestern Pacific Subtropical Anticyclone interannual variability mode equatorial easterly related mode equato-rial westerly related mode ENSO

The Relation between Atmospheric Intraseasonal Oscillation and Summer Severe Flood and Drought in the Changjiang-Huaihe River Basin

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Advances in Atmospheric Sciences 2003年第4期20卷 540-553页

作者：杨辉李崇银 lasg Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029

The intraseasonal oscillation (ISO) is studied during the severe flood and drought years of the Changjiang-Huaihe River Basin with the NCEP/NCAR reanalysis data and the precipitation data in China. The results show that the upper-level (200 hPa) ISO pattern for severe flood (drought) is characterized by an anticyclonic (cyclonic) circulation over the southern Tibetan Plateau and a cyclonic (anti-cyclonic) circulation over the northern Tibetan Plateau. The lower-level (850 hPa) ISO pattern is characterized by an anticyclonic (cyclonic) circulation over the area south of the Changjiang River, the South China Sea, and the Western Pacific, and a cyclonic (anticyclonic) circulation from the area north of the Changjiang River to Japan. These low-level ISO circulation patterns are the first modes of the ISO wind field according to the vector EOF expansion with stronger amplitude of the EOF1.time coefficient in severe flood years than in severe drought years. The analyses also reveal that at 500 hPa and 200 hPa, the atmospheric ISO activity over the Changjiang-Huaihe River basin, North China, and the middle-high latitudes north of China is stronger for severe flood than for severe drought. The ISO meridional wind over the middle-high latitude regions can propagate southwards and meet with the northward propagating ISO meridional wind from lower latitude regions over the Changjiang-Huaihe River Basin during severe flood years, but not during severe drought years.

关键词： summer severe flood and drought in the Changjiang-Huaihe River Basin intraseasonal oscillation ISO circulation pattern

Indices of the Summertime Western North Pacific Subtropical High

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Advances in Atmospheric Sciences 2002年第6期19卷 1004-1028页

作者：陆日宇 lasg Institute of Atmospheric Physics Chinese Academy of Sciences 100029 Beijing

By averaging June-July-August (JJA) mean geopotential height anomalies at 850 hPa over the specified areas, the author proposes two innovative and succinct parameters to objectively define the zonal and meridional displacements of the western North Pacific subtropical high (WNPSH) in summer, respectively. Thus, these two indices and the present results may provide a basis for validating atmospheric general circulation models simulating the WNPSH. For the zonal index, the specified area is the west edge (1.0°–1.0°E, 1.°–30°N) of the WNPSH. For the meridional index, the specified area is the northwest edge (1.0°–1.0°E, 30°–40°N) of the WNPSH. The interannual variations of these two indices are found to be independent. The results from a composite analysis based on the meridional index are in good agreement with previous studies based on case analyses. The two indices are compared with the existing indices announced by the National Climate Center (NCC) in China, on the interannual timescale. Despite slight differences, the interannual variations of the presented indices are basically similar to those of the NCC indices, and thus the circulation and precipitation associated with the present indices exhibit similar features to those associated with the NCC indices. Furthermore, an analysis of the differences between the associations of the present indices and the NCC indices shows that the presented indices are better than the NCC indices. An important result is that the zonal index is related to a more outstanding anomaly of precipitation, especially in East Asia and the Philippine Sea, both based on the presented indices and the NCC indices. The two indices can also be used to describe the seasonal march of the WNPSH during summer, namely, the poleward and eastward shifts. It is found that climatologically, the WNPSH shifts poleward and eastward rapidly in middle July, but the amplitudes of the poleward and eastward shifts are more remarkable in the summers when the

关键词： WNPSH indices interannual variability seasonal evolution

ASYMPTOTIC SOLUTION OF SINGULARLY PERTURBED PROBLEM FOR A NONLINEAR SINGULAR EQUATION

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Applied Mathematics(A Journal of Chinese Universities) 2004年第2期19卷 187-190页

作者： MoJiaqi LinWantao Dept.ofMath. AnhuiNormalUniv.Wuhu241000China lasg InstituteofAtmosphericPhysicsChineseAcademyofSciencesBeijing100029China

The singularly perturbed initial value problem for a nonlinear singular equation is considered. By using a simple and special method the asymptotic behavior of solution is studied.

关键词： nonlinear singular equation singular perturbation upper and lower solutions.

Optimal precursor of the transition from Kuroshio large meander to straight path

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Chinese Journal of Oceanology and Limnology 2013年第5期31卷 1153-1161页

作者：王强马利斌徐强强 Key Laboratory of Ocean Circulation and Waves Institute of Oceanology Chinese Academy of Sciences lasg Institute of Atmospheric Physics Chinese Academy of Sciences University of Chinese Academy of Sciences East China Sea Fisheries Research Institute Chinese Academy of Fishery Sciences

We used the conditional nonlinear optimal perturbation(CNOP) method to explore the optimal precursor of the transition from Kuroshio large meander(LM) to straight path within a barotropic inflowoutflow model,and found that large amplitudes of the optimal precursor are mainly located in the east of Kyushu,which implies that perturbations in the region are important for the transition from LM to straight ***,we investigated the transition processes caused by the optimal precursor,and found that these processes could be divided into three *** the first stage,a cyclonic eddy is advected to the formation region of the Kuroshio large meander,which enhances the LM path and causes a cyclonic eddy to shed from the Kuroshio *** process causes the LM path to change into a small meander ***,the small meander is maintained for a period because the vorticity advection is balanced by the beta effect in the second *** the third stage,the small meander weakens and the straight path ultimately *** positive vorticity advecting downstream is responsible for this *** exploration of the optimal precursor will conduce to improve the prediction of the transition processes from LM path to straight path,and its spatial structure can be used to guide Kuroshio targeted observation studies.

关键词： Kuroshio large meander (LM) precursor conditional nonlinear optimal perturbation (CNOP)

Summertime Subtropical Countercurrent on isopycnals in the western North Pacific

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Chinese Science Bulletin 2002年第9期47卷 786-789页

作者： LI Rongfeng YOU Xiaobao P.Chu lasg Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Department of Oceanography Naval Postgraduate SchoolMontereyCA93943USA

Circulations on isopycnals (σθ) in the western North Pacific were investigated by using P-vector method; the data were taken from the U.S. Navy’s climatological temperature and salinity dataset (public domain) with 1.2°×1.2° resolution. Results not only show the main circulation systems on isopycnals in the western North Pacific such as the North Equatorial Current (NEC), Kuroshio and Ku-roshio Countercurrent, but also reveal the Subtropical Countercurrent (STCC) clearly. In this note we pay attention to discussing the distribution of STCC in summer (in June). The STCC flows eastward along a winding road; on shallow isopycnals, the STCC originates from the area east of Bashi Strait at about 1.2.5°E; with the isopycnals increasing, the origin and flow core of STCC move to north and east, but the main part of STCC is still between 1.?and 23.5°N, i.e. near the Tropic of Cancer. There exists STCC on all isopycnals between the sea surface and 25.8σθ.The current vectors of STCC on isopycnals are

关键词： P-vector method isopycnals Subtropical Countercur-rent.

Implementing a New Snow Scheme in Simplified Simple Biosphere Model

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Advances in Atmospheric Sciences 2001年第3期18卷 335-354页

作者：孙菽芬薛永康 lasg Institute of Atmospheric Physics Chinese Academy of Sciences 100029 Beijing

This paper describes a modified version of SSIB through implementing a new snow model (SAST) in Simplified Simple Biosphere Model SSIB for climate study and presents the evaluation results by testing the scheme based on the field data from Russia and France. The relevant equations in the scheme are given, which describe complicated interactive processes among air-vegetation-snow-soil continuum through mass and heat exchange. An efficient numerical scheme is developed to solve the nonlinear equations successfully. By using the field data from Russia and France, the function of the new scheme is evaluated. The numerical results from the scheme show good agreement with field data. It indicates that the scheme developed here is workable and can be extended for climate study. Key words Snow cover model (SAST) - SSIB - Implementing - Evaluation This work was supported by the foundation from China: 1.NSF Grant 4983501., 2) National key program G1.98040900—Part 1. 3) NSF 4007501., 4) NSF 49823002.

关键词： Snow cover model (SAST) SSIB Implementing Evaluation