冬季西风环流指数的变率及其与北半球温度变化的关系研究

龚道溢; 王绍武

冬季西风环流指数的变率及其与北半球温度变化的关系研究

龚道溢¹,
王绍武²

1.
北京师范大学资源科学研究所环境演变与自然灾害教育部重点实验室北京 100875
2.
北京大学大气科学系北京 100871

基金项目: 国家自然科学基金(40105007);国家重点基础研究发展规划首批项目(G1998040900)资助

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出版历程
- 收稿日期: 2000-11-16
- 修回日期: 2001-02-20

VARIABILITY OF THE WINTER ZONAL INDEX AND ITS ASSOCIATION WITH THE NORTHERN HEMISPHERIC TEMPERATURE CHANGES

GONG Dao-yi¹,
WANG Shao-wu²

1.
Key Laboratory of Environmental Change and Natural Disaster, Beijing Normal University, Beijing 100875 China
2.
Department of Atmospheric Sciences, Peking University, Beijing 100871, China

摘要

摘要: 用H_40°N-H_65°N即40°N和65°N纬圈平均位势高度的差来定义西风指数,可以很好地反映温带地区西风的强弱。西风环流强的年份,北半球气温通常偏高,主要是中纬度大陆变暖明显,这可能与中高纬度西风强时,向北的经向热量输送也加强有关。在长期变化的趋势上,1950年代以前北半球偏暖时期的指数偏低,而偏冷时期的指数偏高。但近30多年来,伴随全球加速变暖,西风指数也持续加强,这是否与温室效应的加强有关还有待深入研究。
- 西风指数 /
- 变率 /
- 温度
Abstract: The dominant modes of northern hemispheric zonally-mean wind (u) and 500 hPa geopotential height in winter demonstrate two centers with opposite sign. Thus the zonal index can be defined as H_40°N-H_65°N or U_35°N-U_55°N, i.e., the difference in geopotential height (or zonal wind) between 40°N and 65°N (or between 35°N and 55°N). In this paper the zonal index of H_40°N-H_65°N is applied. This kind of zonal index correlate with westerly of 55°N at 0.96. The anomalous variation of the westerly can impact the winter surface temperature significantly. During the high-index years, the northern continent becomes warmer and during the low-index years become colder. The changes in temperature are more significant over the middle-high latitudes. Correlation between the zonal index and the meridional heat flux show that there are more heat transporting to the higher latitudes through the intensified eddies activity with the stronger westerlies. On the interdecadal time scale, the temperature and zonal index vacillate out of phase before the 1950s, i.e., the low-index associate with warmer periods and high-index with colder periods. But during the last three decades, both the northern hemispheric mean temperature and zonal index demonstrate significant upward trends. Analysis indicates the increasing greenhouse effect may trigger the recent positive trend in zonal index.
- zonal index /
- variability /
- temperature

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参考文献(17)

[1]	THOMPSON D W J,WALLACE J M.The Arctic Oscillation signature in the wintertime geopotential height and temperaturefields[J].Geophysical Res Lett,1998,25:1297-1300.
[2]	THOMPSON D W J,WALLACE J M.Annular modes in the extratropical circulation,part I:month-to-month variability[J].JClimate,2000,13:1000-1016.
[3]	HURRELL J W.Decadal trends in the North atlantic oscillation: regional temperatures and precipitation[J].Science,1995,269:676-679.
[4]	HURRELL J W.Influence of variations in extratropical wintertime teleconnections on northern hemisphere[J].Geophy ResLett,1996,23: 665-668.
[5]	LORENZ E.Seasonal and irregular variations of the northern hemisphere sea-level pressure profile[J].J Meteorology,1951,8: 52-59.
[6]	BRANSTATOR G.The relationship between zonal mean flow and quasi-stationary waves in the midtroposhpere[J].J AtmosSco,1984,41:2163-2178.
[7]	KIDSON J W.Index cycles in the northern hemisphere during the global weather experiment[J].Mon Wea Rev,1985,113:607-623.
[8]	TING M,HOERLING M P,XU T Y,et al.northern hemisphere teleconnection patterns during extreme phases of the zonal-mean circulation[J].J Climate,1996,9:2614-2633.
[9]	WALLACE J M,HSU H.Another look at the cycle index[J].Tellus,1985,37A:478-486.
[10]	LIMPASUVAN V,HARTMANN D L.Eddies and the annular modes of climate variability[J].Geophysics Res Lett,1999,26: 3133-3136.
[11]	ROBINSON W A.Eddy feed-backs on the zonal index and eddy-zonal flow interactions induced by zonal flow transience[J].J Atmos Sci,1994,51:2553-2562.
[12]	WILLETT H C.Long-period fluctuations of the general circulation of the atmosphere[J].J Meteor,1949,6:34-50.
[13]	SHINDILL D,RIND D,BALACHANDRAN N,ed al.Solar cycle variability,ozone and climate[J].Science,1999,284(5412): 305-308.
[14]	FYFE J C,BOER G J,FLATO G M.The arctic and antarctic oscillations and their projected changes under globalwarming[J].Geophysical Res Lett,1999,26:1601-1604.
[15]	.HOUGHTON J T,MEIRA F F G T,CALLANDER B A,et al.Climate change 1995: the science of climate change[M].Cambridge Univ Press,Cambridge,U K,1996.146.
[16]	GITEMAN A I,RISBEY J S,KASS R E,eds.Trends in the surface meridional temperature gradient[J].Geophy Res Lett,1997,24: 1243-1246.
[17]	DESER C.On the teleconnectivity of the "Arctic oscillation"[J].Geophy Res Lett,2000,27,779-782.