东亚地区汛期OLR季节内振荡型的年际变化特征

 分析了1979—2005年5—8月东亚地区向外长波辐射（OLR）主要的空间模态和季节内振荡（ISO）强度的年际变化特征，并研究了各个模态主要ISO型之间的联系。结果表明，5—8月东亚地区OLR存在3种主要的空间模态：西太平洋偶极型（WPD），西太平洋经向型（MWP）和东亚中纬太平洋波列（MEAP），其时间变化表现为10～20，20～30和30～70d的周期振荡，其强度均存在极显著的年际变化，由东亚夏季风区加热强迫和大气内部非线性相互作用引起。WPD的主要ISO型之间相互独立，MWP和MEAP的不同ISO型之间存在强的相互作用。深入研究这3个模态的20～30和10～20d振荡变化特征，对于东亚地区夏季10～30d延伸期预报具有重要意义。

Interannual Variations of Intraseasonal Oscillation Pattern of OLR in Rainy Seasons in East Asia

Observational data of the Outgoing Longwave Radiation(OLR) from May to August during the period of 1979—2005 were analyzed to investigate the spatial and temporal characteristics of principal Intraseasonal Oscillation(ISO) patterns and theirs interannual variations over East Asia. The relationships between these ISO patterns were also discussed. Results indicate that there are three kinds of the notable spatial patterns: Western Pacific Dipole(WPD) pattern, Meridional Western Pacific(MWP) pattern and Middle Latitude East/Pacific(MEAP) pattern. It is found that these patterns are mainly of periodic oscillations of 10～20, 20～30 and 30～70 days, and the interannual variations of the intensity are predominant, which are associated with the heating forcing over East Asia monsoon region and nonlinear atmospheric interaction. For different time scales, the variations between the principal ISO modes of WPD pattern are independent processes, but the interactions between the principal ISO modes of MWP and MEAP patterns are dominant. These findings may have implications in improving extended-range weather forecasting for 10～30 days in East Asia summer.