大气科学2017，Vol.41Issue(6)：1204-1220,17.DOI:10.3878/j.issn.1006-9895.1703.16277
2002年夏季中高纬大气准双周振荡对华南降水的影响
Influence on the South China Rainfall Anomalies of the Atmospheric Quasi-Biweekly Oscillation in Mid-High Latitude during the Summer of 2002
摘要
Abstract
The satellite-based TRMM rainfall and the JRA55 atmospheric reanalysis datasets are used to investigate the structure and evolution of extratropical atmospheric intraseasonal oscillation and its impact on anomalous rainfall over South China (SC) in the summer (May to August) of 2002.Wavelet and power spectra analyses demonstrate that the intraseasonal variability of the SC rainfall during the summer of 2002 was characterized by a significant quasi-biweekly oscillation (QBWO) with a period of 10-30 days.Composite analyses show that such a QBWO of the SC rainfall was not only related to alternate occurrences of the anticyclone and cyclone anomalies in the lower troposphere over the coastal region of SC that modulate the western North Pacific subtropical high entering or leaving the South China Sea,but also largely dependent on the extratropical atmospheric oscillation in the middle and upper troposphere.The QBWO in the upper troposphere was characterized by a southeastward-propagating wave train consisting of a series of anomalous cyclones and anticyclones,which were aligned in a northwest-southeast direction over Eurasian continent.When the anomalous anticyclone and cyclone were respectively located over the Tibetan Plateau and northern China as the wave train moved,the upper tropospheric divergence between this dipole in anomalies was favorable for the development of ascending motions over SC,leading to above-normal rainfall;in the opposite situation,below-normal rainfall occurred over SC.For the transition between dry and wet episodes of the QBWO,anomalous tropospheric horizontal temperature advection and absolute vorticity anomalies in the upper troposphere above the subtropics caused by the southward migration of the wave train are two dominant factors leading to the alternation between ascending and descending motions over SC as well as the reversal of the corresponding meridional circulations.Local sensible heating anomalies also make certain contributions to the above process.Significantly positive correlations were found when the 500-hPa geopotential height anomalies over the Tibetan Plateau led the SC rainfall anomalies by 4 days (that is,a phase lag of 1/4 period of the QBWO),which implies that the 500-hPa geopotential height anomalies around the Tibetan Plateau may be a potential predictor for the forecast of the intraseasonal variation of rainfall over SC.关键词
华南降水异常/准双周振荡/中高纬大气环流Key words
South China rainfall anomalies/Quasi-biweekly oscillation/Extratropical atmospheric circulation分类
天文与地球科学引用本文复制引用
孔晓宇,毛江玉,吴国雄..2002年夏季中高纬大气准双周振荡对华南降水的影响[J].大气科学,2017,41(6):1204-1220,17.基金项目
国家自然科学基金项目91537103、 41375087,全球变化与海气相互作用专项GASI-IPOVAI-03,中国科学院前沿科学重点研究项目QYZDY-SSW-DQC018 National Natural Science Foundation of China (Grants 91537103,41375087),National Program on Global Change and Air-Sea Interaction (Grant GASI-IPOVAI-03),Frontier Program of the Chinese Academy of Sciences (Grant QYZDY-SSW-DQC018) （Grants 91537103,41375087）
