oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Role of snow depth in spring of Tibetan Plateau in onset of South China Sea summer monsoon
青藏高原春季积雪在南海夏季风爆发过程中的作用

YU Le-Jiang,HU Dun-Xin,
于乐江
,胡敦欣

地球物理学报 , 2008,
Abstract: The role of snow depth of Tibetan Plateau in the onset of South China Sea summer monsoon and the influence of ENSO on snow depth of Tibetan Plateau are investigated with use of data from ECMWF reanalysis and NCEP/NCAR reanalysis.The results are as follows:(1) The snow depth data from ECMWF reanalysis are tested and reliable,and can be used to study the influence of snow depth of Tibetan Plateau on the onset of South China Sea summer monsoon;(2) Anomaly of snow depth of Tibetan Plateau causes anomaly in air temperature and its contrast between the Indian Ocean and the continent resulting in easterly wind anomaly over 500 hPa and hence as well as in the atmospheric circulation in the lower layer.For the year of negative anomaly of snow depth a westerly wind anomaly with a cyclone pair takes place,while for positive anomaly of snow depth an easterly anomaly occurs with an anticyclone pair;(3) While positive anomaly of SST occurs in the eastern Pacific Ocean,positive anomaly of air pressure also takes place over the eastern Indian Ocean and the South China Sea,causing stronger meridional pressure gradient between the ocean and continent and then westerly wind anomaly.At the same time,the atmospheric pressure increases in the northern Tibetan Plateau,northerly wind gets stronger,and subtropical front strengthens.All of these are favorable for snowfall over Tibetan Plateau.
Relationship between Atmospheric Heat Source in Tibetan Plateau and Abnormality of Meiyu in Changjiang-Huaihe River Valley
青藏高原大气热源与江淮梅雨异常的关系

MAO Wen-shu,GONG Yuan-fa,ZHOU Qiang,
毛文书
,巩远发,周强

高原气象 , 2009,
Abstract: Based on the precipitation of Meiyu at 37 stations in the Changjiang-Huaihe River valley and the daily reanalysis geopotential height,wind field,humidity field and surface pressure field data(Grid 2.5°×2.5°) from 1954 to 2001,the relationship between the atmospheric heat source in the Tibetan Plateau and the abnormality of Meiyu in the Changjiang-Huaihe River valley is studied by terms of the fuzzy cluster analysis,EOF,composite analysis,SVD analyses,and so on. The results show that there are notable correlation between the reginal index of Meiyu precipitation in the good(poor) Meiyu year and the atmospheric heat source in the Tibetan Plateau. The atmospheric heat source in the Tibetan Plateau is devided into the east and north patterns according to the 90°E. There are positive or negative correlation between the atmospheric heat source in the Tibetan Plateau and the precipitation in the Changjiang-Huanhe River valley. The atmospheric heat source in the eastern (western) of the Tibetan Plateau is marked increasing(decreasing) while the precipitation is is marked increasing(decreasing) in the Changjiang-Huaihe River valley,and vice verse.
Contemporaneous Relationships between Summer Atmospheric Heat Source over the Tibetan Plateau and Drought/Flood in Eastern Southwest China
夏季青藏高原大气热源与西南地区东部旱涝的关系

LI Yonghua,LU Chuhan,XU Haiming,CHENG Bingyan,WANG Yong Chongqing Climate Center,Chongqing Key Laboratory of Meteorological Disaster of Ministry of Education,Nanjing University of Information Science & Techno-logy,Nanjing,
李永华
,卢楚翰,徐海明,程炳岩,王勇

大气科学 , 2011,
Abstract: Based on the NCEP/NCAR reanalysis monthly data and daily precipitation data at 20 stations in eastern Southwest China from 1959 to 2006, the features of atmospheric heat source over the Tibetan Plateau and the key area associated with the drought/flood in summer over eastern Southwest China have been analyzed. Results show that there is a close relationship between the flood/drought over eastern Southwest China and the intensity of the atmospheric heat source over southeastern Tibetan Plateau (key area), i.e., the rainfall is more than normal while the heat source is stronger. It is propitious to appearance of circulation making for the summer rainfall in eastern Southwest China; furthermore, the vapor transport and convergent upward velocity are strengthened, the East Asian summer monsoon is weaker, and the ridge positions of the western Pacific subtropical high and South Asia high lean to south when the intensity of the atmospheric heat source over eastern Tibetan Plateau (key area) is stronger than normal, vice versa.
Relationship between the atmospheric heat source over Tibetan Plateau and the heat source and general circulation over East Asia
YueNan Wang,Bo Zhang,LongXun Chen,JinHai He,Wei Li,Hua Chen
Chinese Science Bulletin , 2008, DOI: 10.1007/s11434-008-0327-0
Abstract: On the basis of NCEP/NCAR version I daily reanalysis data from 1971 to 2000 and by the methods of inverse calculation, correlation analysis and comparative analysis, the influences of atmospheric heat source (AHS) over the Tibetan Plateau on the large-scale AHS and the general circulation in summer are studied in this paper. The results show that AHS over the plateau in summer may trigger a heat source wavetrain propagating northeastward along the coast from the East Asian continent and West Pacific to Bering Strait-Arctic or even North America. In addition, if AHS over the eastern plateau is intense, South Asian High moves to southeast and West Pacific subtropical high moves to southwest; on the contrary, if AHS over the eastern plateau is weak, South Asian High moves to northwest and West Pacific subtropical high moves to northeast. Therefore, South Asian High and West Pacific subtropical high move in the horizontally-opposite directions in terms of interannual variation, for which AHS over the eastern plateau seems to be thermodynamically responsible.
Reliability of NCEP/NCAR reanalysis data in the Himalayas/Tibetan Plateau

XIE Aihong,REN Jiawen,QIN Xiang,KANG Shichang,

地理学报 , 2007,
Abstract: Due to the difficult logistics in the extreme high elevation regions over the Himala-yas and Tibetan Plateau, the observational meteorological data are very few. In 2003, an automatic weather station was deployed at the northeastern saddle of Mt. Nyainqentanglha (NQ) (30°24′44.3″ N, 90°34′13.1″ E, 5850 m a.s.l.), the southern Tibetan Plateau. In 2005, another station was operated at the East Rongbuk Glacier Col (28°01′0.95″ N, 86°57′48.4″ E, 6523 m a.s.l.) of Mt. Qomolangma. Observational data from the two sites have been com-pared with the reanalysis data from the National Centers for Environmental Predic-tion/National Center for Atmospheric Research (NCEP/NCAR), reliability of NCEP/NCAR reanalysis data has been investigated in the Himalayas/Tibetan Plateau region. The reanaly-sis data can capture much of the synoptic-scale variability in temperature and pressure, al-though the reanalysis values are systematically lower than the observation. Furthermore, most of the variability magnitude is, to some degree, underestimated. In addition, the weather event extracted from the NCEP/NCAR reanalyzed pressure and temperature prominently appears one day ahead of the observational data on Mt. Qomolangma, while on Mt. NQ it occurs basically in the same day.
Atmospheric hydrological budget with its effects over Tibetan Plateau

BAI Jingyu,XU Xiangde,

地理学报 , 2004,
Abstract: Based on 1961-2000 NCEP/NCAR monthly mean reanalysis datasets, vapor transfer and hydrological budget over the Tibetan Plateau are investigated. The Plateau is a vapor sink all the year round. In summer, vapor is convergent in lower levels (from surface to 500 hPa) and divergent in upper levels (from 400 to 300 hPa), with 450 hPa referred to as level of non-divergence. Two levels have different hydrologic budget signatures: the budget is negative at the upper levels from February to November, i.e., vapor transfers from the upper levels over the plateau; as to the lower, the negative (positive) budget occurs during the winter (summer) half year. Evidence also indicates that Tibetan Plateau is a "vapor transition belt", vapor from the south and the west is transferred from lower to upper levels there in summer, which will affect surrounding regions, including eastern China, especially, the middle and lower reaches of the Yangtze. Vapor transfer exerts significant influence on precipitation in summertime months. Vapor transferred from the upper layers helps humidify eastern China, with coefficient -0.3 of the upper budget to the precipitation over the middle and lower reaches of the Yangtze (MLRY); also, vapor transferred from east side (27.5o-32.5oN) of the upper level has remarkable relationship with precipitation, the coefficient being 0.41. The convergence of the lower level vapor has great effects on the local precipitation over the plateau, with coefficient reaching 0.44, and the vapor passage affects the advance and retreat of the rainbelt. In general, atmospheric hydrologic budget and vapor transfer over the plateau have noticeable effects on precipitation of the target region as well as the ambient areas.
Variation of Tibetan Plateau Summer Monsoon and Its Effect on Precipitation in East China
近几十年青藏高原夏季风变化趋势及其对中国东部降水的影响

Hua Wei,Fan Guangzhou,WANG Bingyun,
华维
,范广洲,王炳赟

大气科学 , 2012,
Abstract: Based on the NCEP/NCAR, NCEP/DOE and ERA40 reanalysis data and the monthly precipitation data from 596 stations of China, the variation of the Tibetan Plateau (TP) summer monsoon and its impact on precipitation in eastern China are investigated by using the correlation analysis, the wavelet analysis, and the cross-spectral analysis. The results show that the plateau summer monsoon exhibits the strong interannual and long-term variability. It also shows an obviously upward trend during 1958-2010. The further analysis reveals that the abnormal enhancement of the plateau summer monsoon changes the Asia atmospheric circulation and then weakens the Asian summer monsoon. This leads to an increase of monsoon rainfall over the middle-lower reaches of the Yangtze River and a decrease over North China and South China. The strengthening of the plateau summer monsoon over the past 50 years may be related to the enhancement of thermal difference between the TP and its surrounding plains in the middle-upper troposphere (especially of the increase of thermal difference between the TP and the plain in eastern China).
The Impact of Atmospheric Heat Sources over the Eastern Tibetan Plateau and the Tropical Western Pacific on the Summer Rainfall over the Yangtze-River Basin
JIAN Maoqiu,QIAO Yunting,YUAN Zhuojian,LUO Huibang,
JIAN Maoqiu
,QIAO Yunting,YUAN Zhuojian,LUO Huibang

大气科学进展 , 2006,
Abstract: The variability of the summer rainfall over China is analyzed using the EOF procedure with a new parameter (namely, mode station variance percentage) based on 1951-2000 summer rainfall data from 160 stations in China. Compared with mode variance friction, the mode station variance percentage not only reveals more localized characteristics of the variability of the summer rainfall, but also helps to distinguish the regions with a high degree of dominant EOF modes representing the analyzed observational variable.The atmospheric circulation diagnostic studies with the NCEP/NCAR reanalysis daily data from 1966 to 2000 show that in summer, abundant (scarce) rainfall in the belt-area from the upper-middle reaches of the Yangtze River northeastward to the Huaihe River basin is linked to strong (weak) heat sources over the eastern Tibetan Plateau, while the abundant (scarce) rainfall in the area to the south of the middle-lower reaches of the Yangtze River is closely linked to the weak (strong) heat sources over the tropical western Pacific.
Reliability of NCEP/NCAR reanalysis data in the Himalayas/Tibetan Plateau
NCEP/NCAR 再分析资料在喜马拉雅山-青藏高原气象研究中的可行性分析

Xie Aihong,Ren Jiawen,Qin Xiang,Kang Shichang,
谢爱红
,任贾文,秦翔,康世昌

地理学报(英文版) , 2007,
Abstract: Due to the difficult logistics in the extreme high elevation regions over the Himalayas and Tibetan Plateau, the observational meteorological data are very few. In 2003, an automatic weather station was deployed at the northeastern saddle of Mt. Nyainqentanglha (NQ) (30°24′44.3″N, 90°34′13.1″E, 5850 m a.s.l.), the southern Tibetan Plateau. In 2005, another station was operated at the East Rongbuk Glacier Col (28°01′0.95″N, 86°57′48.4″E, 6523 m a.s.l.) of Mt. Qomolangma. Observational data from the two sites have been compared with the reanalysis data from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR), reliability of NCEP/NCAR reanalysis data has been investigated in the Himalayas/Tibetan Plateau region. The reanalysis data can capture much of the synoptic-scale variability in temperature and pressure, although the reanalysis values are systematically lower than the observation. Furthermore, most of the variability magnitude is, to some degree, underestimated. In addition, the weather event extracted from the NCEP/NCAR reanalyzed pressure and temperature prominently appears one day ahead of the observational data on Mt. Qomolangma, while on Mt. NQ it occurs basically in the same day. Foundation: National Natural Science Foundation of China, No.40501015; No. 90411003; Innovation Program of CAS, No.KZCX3-SW-344; No.KZCX3-SW-354 Author: Xie Aihong (1975–), Ph.D Candidate, specialized in glacier and climate change.
RELATIONSHIPS BETWEEN AN ICE CORE RECORDS FROM SOUTHERN TIBETAN PLATEAU AND ATMOSPHERIC CIRCULATION OVER ASIA
青藏高原南部冰芯记录与大气环流的关系*

PAMayewski,SKaspari,Kang Shichang,Qin Dahe,Ren Jiawen,PAMayewski,Hou Shugui,Zhang Dongqi,Zhang Yongjun,SKaspari,
康世昌
,秦大河,任贾文,P.A.Mayewski,侯书贵,张东启,张拥军

第四纪研究 , 2006,
Abstract: Hydrogen isotope (δD) and annual accumulation records covering the period A.D. 1952~1998 were reconstructed using a 29.5m ice core from the col of the Lanong Glacier (5850m a.s.l.) on the eastern saddle of Mt. Nyainqêntanglha (NQ), Southern Tibetan Plateau (TP). Using NCEP/NCAR Reanalysis data, we explore the relationships between the annual δD and accumulation records from the ice core and primary components of the climate system. Linear correlation analysis between δD and climate components indicates that δD variations are correlated with summer precipitation, winter surface pressure, and geopotential height in both winter and summer over the South Asian and TP region. Summer precipitation and δD are negatively correlated over regions of northern India and the Bay of Bengal, while a positive correlation exists over the north of TP. This is consistent with the amount effect controlling δD values during the summer monsoon season. A negative relationship between δD and winter surface pressure over central Asia suggests that high pressure acts as a barrier against winter moisture transport with higher δD values from the Westerlies. Negative correlations between δD and geopotential height in both summer and winter over Asia indicate that stronger atmospheric circulation over Asia corresponds to lower δD values. Linear correlation analysis between annual accumulation and climate components for the 47 year overlap periods indicates that annual accumulation variations are closely correlated with sea surface and 500hPa air temperature over the North Indian Ocean and atmospheric circulation (surface pressure and geopotential height) over Asia. An Intensification of atmospheric circulation and increase of sea surface and air temperatures, resulting in intensified moisture availability and moisture transport, have been a major cause for the increase of ice core accumulation over the Mt. NQ region since the 1980s. Associations between atmospheric circulation and the NQ δD and accumulation records found in this study can be applied to future studies utilizing longer ice core records to reconstruct atmospheric circulation farther back in time.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.