中国西北东部汛期降水对青藏高原东部春季感热在准3a周期上的响应

Quasi 3-year period response of the rainy season precipitation over the eastern parts of Northwest China to the spring sensible heat flux over the eastern part of the Tibetan Plateau

利用1960—2010年中国西北东部地区39个气象站的逐日降水资料和NCEP/NCAR月平均地表感热通量再分析资料以及大气环流各要素场资料,通过多锥度-奇异值分解(MTM-SVD)等方法,分析了中国西北东部汛期降水、青藏高原东部春季感热的周期振荡特征以及它们在准周期循环上的协同耦合关系。结果表明,感热与降水均存在显著的准3 a周期,其耦合场在准3 a周期上表现也最为明显。当青藏高原东部春季感热在青藏高原主体上偏强(弱)时,对应中国西北东部汛期降水的异常偏多(少)。该准3 a周期循环上的协同关系在1960—1982年表现最为显著,1983—1990年为调整阶段,90年代之后又逐渐明显。青藏高原东部春季感热对大气环流的持续加热过程影响西北东部汛期降水,且主要体现在8月。

By using the precipitation data at 39 stations in the eastern parts of Northwest China during 1960-2010 and the NCEP/NCAR reanalysis data,the quasi-periodic cycles of precipitation during the rainy season over the eastern parts of Northwest China,spring sensible heat flux over the eastern part of the Tibetan Plateau and their synergistic coupling are analyzed through the Multi Taper Method-Singular Value Decomposition（MTM-SVD）.The results show that both the sensible heat flux and precipitation have a significant quasi 3-year period,and their coupling field also shows a significant 3-year period.When the spring sensible heat flux becomes stronger（weaker）over the eastern part of the Tibetan Plateau,there is more（less）precipitation over the eastern parts of Northwest China during the rainy season.The most significant period of such quasi 3-year period synergistic relationship appears during 1960-1982,and there is an adjustment stage in 1983-1990,with the quasi 3-year period appeared again after 1990 s.The continuous heating process of the former can affect the latter,which are mainly embodied in August.