贵州主汛期季节内振荡特征

On characteristics of intra-seasonal oscillation in main rainy season over Guizhou Province

利用NCEP提供的OLR逐日再分析资料与贵州省气象局提供的85站逐日降水资料通过小波分析、序列相关、带通滤波、合成分析等方法,分析了1979—2012年大气季节内振荡与贵州主汛期降水的相关性和影响区域.分析得到:大气季节内振荡的对流活动对贵州主汛期降水占主要贡献,且大值区分布在贵州省中东部.通过将1979—2012年中大气季节内振荡活跃与不活跃的年份进行挑选,对其波动特征、影响区域以及传播路径进行对比分析.结果表明,ISO活跃年时,ISO波动强度大周期较明显,6—7月上旬从副热带西太平洋向西传播到孟加拉湾北部,7月下旬—8月从副热带西太平洋向西传播到孟加拉湾西北部;ISO不活跃年时,ISO波动强度小周期不明显,6—7月下旬和7月中旬—8月底从阿拉伯海北部向东传播到副热带西太平洋.

Applying the approaches of the wavelet analysis,array correlation,band pass filter and composite analysis,the relationship between the convective activity of Intra-Seasonal Oscillation（ ISO） and the precipitation in the main flood season over Guizhou Province during 1979—2012 has been analyzed based on the OLR data and precipitation data at 85 stations of Guizhou.Results show that the convective activity of ISO makes great contribution to the summer precipitation in Guizhou with the large value center in the central-eastern Guizhou. The fluctuation characteristics,which affected area and propagation paths of the ISO in the stronger or the weaker years from 1979 to 2012 have also been examined.In the stronger years,ISO with the great intensity and the obvious oscillation cycle westward propagated from the subtropic western Pacific to the northern bay of Bengal（ BOB）during June—early July,and from the subtropical western Pacific to the northwest BOB during late July—August.While in the weaker years,ISO with the low intensity and the unobvious oscillation cycle eastward spread from the northern Arabian sea to subtropical western Pacific during June—late July and during middle July—late August.