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Search Results: 1 - 10 of 77978 matches for " CHEN Longxun "
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Role of atmospheric heat source/sink over the Qinghai-Xizang Plateau in quasi-4-year oscillation of atmosphere-land-ocean interaction
Ping Zhao,Longxun Chen
Chinese Science Bulletin , 2001, DOI: 10.1007/BF03187178
Abstract: Using 1961–1995 monthly atmospheric apparent heat source/sink/〈Q 1〉 over the Qinghai-Xizang Plateau (QXP) and reanalysis data of NCEP/NCAR, and 1961–1994 monthly SST of UK/GISST2, the statistical study is undertaken on the QXP heat source/sink in relation to both atmospheric circulation in Asia and El Ni o/La Ni a events. It is discovered that there exists noticeable interaction in a quasi-4-year period among the 〈Q 1〉 of the QXP, low-level meridional winds east of the QXP, low-level zonal winds in the equatorial Pacific, SST in the equatorial eastern Pacific, and the circulation at mid and high latitudes north of the QXP. They have difference in phase. The cold source intensity of the QXP in winter favours a low-level meridional wind anomaly to prevail in the mainland of China and its coast east of the QXP and to last until the subsequent autumn. The wind anomaly can induce a low-level zonal wind anomaly of the tropic Pacific that finally affects an El Ni o/La Ni a event in the autumn and subsequent winter. The event in autumn/winter has effect on the deep trough position and cold air track of East Asia in next winter that influences the intensity of the QXP winter cold source.
Characteristics of the Seasonal Variation of the Surface Total Heating over the Tibetan Plateau and Its Surrounding Area in Summer 1998 and Its Relationship with the Convection over the Subtropical Area of the Western Pacific
1998年夏季青藏高原及其邻近地区地面总热源季节变化特征及其与西太平洋副热带地区对流的关系

LI Wei,CHEN Longxun,
LI Wei
,CHEN Longxun

大气科学进展 , 2003,
Abstract: Using the dataset of 1998 TIPEX, the data of 6 automatic heat balance observational stations (AWS)from May to August 1998, a dataset of 52 surface observational stations over the Tibetan Plateau (TP)and its adjacent region, the daily rainfall amounts from about 300 stations in China, the outgoing longwaveradiation (OLR) data received by the National Satellite Meteorological Center(NSMC) of China, and TBBdata from GMS remote sensing of Japan, the characteristics of the seasonal variation of the surface totalheating over TP and its surrounding area in summer 1998 and its relationship with the convection overthe subtropical area of the western Pacific is studied in this paper. The results show that the surface totalheating over TP had a close relationship with the onset of the rainy season, and after the onset of the rainyseason, the regional mean surface total heating over TP decreased distinctly. Furthermore, the regionalmean surface total heating over TP had very good negative correlation with TBB over the subtropicalarea of the western Pacific along 20-30°N, which shows that the surface total heating over TP was able toaffect the convection over the subtropical area of the western Pacific.
Interannual Variability of Atmospheric Heat Source/Sink over the Qinghai-Xizang (Tibetan) Plateau and its Relation to Circulation
青藏高原大气热量源汇年际变化青藏高原大气热量源汇年际变化

Zhao Ping,Chen Longxun,
Zhao Ping
,Chen Longxun

大气科学进展 , 2001,
Abstract: Based on the 1961-1995 atmospheric apparent heat source/sink and the 1961-1990 snow-cover days and depth over the Qinghai-Xizang Plateau (QXP) and the 1961-1995 reanalysis data of NCEP/NCAR and the 1975-1994 OLR data, this paper discusses the interannual variability of the heat regime and its relation to atmospheric circulation. It is shown that the interannual variability is pronounced, with maximal variability in spring and autumn, and the variability is heterogeneous horizontally. In the years with the weak (or strong) winter cold source, the deep trough over East Asia is to the east (or west) of its normal, which corresponds to strong (or weak) winter monsoon in East Asia. In the years with the strong (or weak) summer heat source, there exists an anomalous cyclone (or anticyclone) in the middle and lower troposphere over the QXP and its neighborhood and anomalous southwest (or northeast) winds over the Yangtze River valley of China, corresponding to strong (or weak) summer monsoon in East Asia. The summer heat source of the QXP is related to the intensity and position of the South Asia high. The QXP snow cover condition of April has a close relation to the heating intensity of summer. There is a remarkable negative correlation between the summer heat source of the QXP and the convection over the southeastern QXP, the Bay of Bengal, the Indo-China Peninsula, the southeastern Asia, the southwest part of China and the lower reaches of the Yangtze River and in the area from the Yellow Sea of China to the Sea of Japan.
The Relationship between the Asian/Australian Monsoon and ENSO on a Quasi-Four-Year Scale
亚澳季风异常与ENSO准四年变化的联系分析

Zhu Yanfeng,Chen Longxun,
Zhu Yanfeng
,Chen Longxun

大气科学进展 , 2002,
Abstract: The interannual variability of tropical zonal wind and the relationship between ENSO and the Asian/Australian monsoon in different phases are discussed. Results show that the tropical zonal wind strongly couples with the central-eastern Pacific SST on a quasi-four-year scale. During the period of El Nino, the East Asian winter (summer) monsoon is weaker (stronger) and the South Asian summer monsoon is weaker than normal. Conversely, the East Asian winter (summer) monsoon is stronger (weaker) and the South Asian summer monsoon is stronger than normal during the period of La Nina. The anomalous northerly over East Asia induces an anomalous westerly over the western equatorial Pacific, which favors the appearance of positive SST anomalies in the central-eastern Pacific. The development of El Nino requires the persistence of a westerly over the central-eastern Pacific. The convergence between anomalous northerlies from the central North Pacific (not from the East Asian continent) and anomalous southerlies from Northeast Australia favors the persistence of a westerly over the central-eastern Pacific. In particular, the anomalous southerlies from Northeast Australia play a key role in the onset of strong westerly anomalies over the tropical central-eastern Pacific.
Calculation of Solar Albedo and Radiation Equilibrium over the Qinghai-Xizang Plateau and Analysis of Their Climatic Features
Calculation of Solar Albedo and Radiation Equilibrium over the Qinghai-Xizang Plateau and Analysisof Their Climatic Features

Zhao Ping,Chen Longxun,
Zhao Ping
,Chen Longxun

大气科学进展 , 2000,
Abstract: Using radiation data from the Automatic Weather Stations (AWSs) for thermal balance observations, which were set up at Lhasa, Nagqu, Xigaze and Nyingchi by the Sino-Japanese Asian Monsoon Mechanism Co-operative Project in 1993-1996, and 1985-1989 Earth Radiation Balance Experiment (ERBE) measurements of Langley Research Center/NASA of US, and 1961-1996 monthly mean data from 148 surface stations over the Qinghai-Xizang Plateau (QXP) and its neighborhood, study is performed on empirical calculation methods of surface albedo, surface total radiation, planetary albedo and outgoing longwave radiation with the climatic features of radiation balance at the surface and the atmospheric top examined. Evidences suggest that the empirical formulae for surface albedo, planetary albedo, surface total radiation and outgoing longwave radiation from the atmospheric top are capable of describing their seasonal and interannual variations over the QXP. The surface albedo is marked by noticeable seasonal variation and yearly mean of 0.22 with the maximum of 0.29 in January and minimum of 0.17 in July and August; in winter the albedo has great horizontal difference, bigger in the mountains than in the river valleys, and small in summer. The planetary albedo shows a smaller range of its annual variation with the yearly mean of 0.37, the maximum (minimum) occurring in February and March (autumn). In winter its high-value regions are mainly at Gar (Shiquanhe) in the western QXP and from the southwestern Qinghai to the northeastern Tibet and the low-value area at the northern slope of the central Himalayas; in summer, however, the albedo distribution displays clearly a progressive decrease from southeast to northwest. As for the surface total radiation, its values and annual varying range are smaller in the east than in the southwest. Its high-value center is at the southern slope of the Himalayas in winter and makes a conspicuous westward migration in spring, remaining there for a long time, and it begins to retreat eastward in autumn, Monthly mean values of he surface net radiation are all positive and larger in summer than in winter. The net radiation is significantly intensified under the combined effect of surface total radiation and surface albedo from spring to early summer, resulting in the strongest sector in the mid plateau with its center staying nearly motionless from March to September, and is reduced in autumn dominantly by surface effective radiation. The earth-atmosphere system loses heat outward from October to next February and gains in other months. On an average, the plateau gains heat of 15 W m-2 on an annual basis.
THE MEDIUM-RANGE VARIATIONS OF THE SUMMER MONSOON CIRCULATION SYSTEM OVER EAST ASIA

Chen Longxun,Jin Zuhui,

大气科学进展 , 1984,
Abstract: The Asian monsoon circulation system can be divided into two subsystems, i.e., the East Asian monsoon system(EA MS) and the Indian monsoon system (IMS). In this paper the main elements including the Indian monsoon trough, the South Asian high. the upper easterly jet etc. and the interactions between EAMS and IMS arc dealt with. The basic emphasis is put on the medium-range variations of the EAMS. Some significant results arc obtained.
On Quasi-Biennial Oscillation in Air-Sea System

Shao Yongning,Chen Longxun,

大气科学进展 , 1991,
Abstract: From the COADS (Comprehensive Ocean–Atmosphere Data Set) I and the COADS II, we got a monthly data set of sea surface temperature (SST), zonal and meridional wind components at sea level (U,V) and sea level pressure (SLP) with 4° × 4° grid system covering the period from Jan. 1950 to Dec. 1987 to study the evolutional features of the quasi-biennial oscillation (QBO) in the air-sea system. The analytic method of complex empirical orthogonal function (CEOF) is used to obtain the composite temporal sequences of amplitude (six phases for half a period) for the first and the second main components of SST, U, V and SLP. It is shown from the results that the main characteristics for different phases of the sea surface temperature anomaly’s (SSTA) QBO are warm water / cold water in the equator of the eastern Pacific (EEP). There are two warm or cold water centers of the SSTA in the EEP, which are located in the equator of the central Pacific (ECP) and the east part of the EEP. The features of the source propagation and the influence of these two centers on atmospheric circulation are discussed and it can be seen that in the formation of these two centers, there are different features in oceanic and atmospheric circulations and air-sea coupled process.
The Characteristics of 30-60 Day Oscillation and Its Relations to the Interannual Oscillations

Song Yi,Chen Longxun,

大气科学进展 , 1992,
Abstract: The characteristics of 30-60 day oscillation (hereafter called LFO ) of the outgoing longwave radiation data (OLR) and its relations to the interannual oscillations of the sea surface temperature (SST) are investigated by using the daily OLR data for the period from January, 1979 to December, 1987 and the corresponding monthly SST data. It is found that the LFO the band the interannual oscillations of the SST monthly anomaly (SSTA) interact each other and they all relate to the occurrence and development of El Nino events closely. Before El Nino event happens, it contributes to the SST's warming up and to the SST's quasi-biennial oscillation (called QBO for brevity) and three and half years oscillation (called SO for short) being in warm water phase in the equatorial central and eastern Pacific (ECP and EEP) that the LFO in the equatorial western Pacific (EWP) enhances and propagates eastward; When E1 Nino event takes place, the LFO, SSTA and SSTA's QBO and SO in the EEP interact and strengthen each other; But the warmer SST and the SSTA's QBO and SO in the warm water phase in the EEP contribute to the LFO's weakening in the equatorial Pacific. Moreover, these contribute to the SST in the EEP becoming cold and the SSTA's QBO and SO in the EWP being in cold water phase and then impel the El Nino event to end. 1This work is supported by the National Natural Science foundation of China under Program 49070240.
THE ATMOSPHERIC HEAT BUDGET IN SUMMER OVER ASIA MONSOON AREA

Chen Longxun,Li Weiliang,

大气科学进展 , 1985,
Abstract: For better understanding the mechanism of monsoon formation and designing the numerical simulation of the general atmospheric circulation, a new approach of calculating atmospheric radiation is proposed to investigate the distribution of the atmospheric heat source, and the budget of heat component is recalculated. The results show that there is a tremendous atmospheric heat source region over central India, northeast of the Bay of Bengal, east of the South China Sea and about 10 °N at the west Pacific, among which the heating center with a maximum heating rate of 8 °C/day is located over the Bay of Bengal and the average rate in the Plateau is about 1 °C/day.
Role of atmospheric heat source/sink over the Qinghai-Xizang Plateau in quasi-4-year oscillation of atmosphere-land-ocean interaction

Ping Zhao,Longxun Chen,

科学通报(英文版) , 2001,
Abstract: Using 1961—1995 monthly atmospheric apparent heat source/sink over the Qinghai-Xizang Plateau (QXP) and reanalysis data of NCEP/NCAR, and 1961—1994 monthly SST of UK/GISST2, the statistical study is undertaken on the QXP heat source/sink in relation to both atmospheric circulation in Asia and El Ni o/La Ni a events. It is discovered that there exists noticeable interaction in a quasi-4-year period among the of the QXP, low-level meridional winds east of the QXP, low-level zonal winds in the equatorial Pacific, SST in the equatorial eastern Pacific, and the circulation at mid and high latitudes north of the QXP. They have difference in phase. The cold source intensity of the QXP in winter favours a low-level meridional wind anomaly to prevail in the mainland of China and its coast east of the QXP and to last until the subsequent autumn. The wind anomaly can induce a low-level zonal wind anomaly of the tropic Pacific that finally affects an El Ni o/La Ni a event in the autumn and subsequent winter. The event in autumn/winter has effect on the deep trough position and cold air track of East Asia in next winter that influences the intensity of the QXP winter cold source.
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