瞬变波活动与江淮地区夏季旱涝的关系

利用1951-2000年中国160站逐月降水量资料划分了江淮地区夏季旱涝年。通过对旱涝年500hPa高度距平场的合成分析发现：多雨年鄂霍茨克海阻塞高压稳定维持，少雨年鄂霍茨克海附近的高压脊减弱。为了了解江淮地区旱涝年500hPa中高纬环流形势异常的原因，计算了Eliassen-Palm通量，结果表明多雨年瞬变波对平均气流的强迫作用使经、纬向风异常分布有利于鄂霍茨克海阻塞形势的维持，冷空气向南输送增强，江淮地区降水偏多；少雨年瞬变波对平均气流的强迫作用使鄂霍茨克海高压脊减弱，冷空气向南输送减弱，江淮地区降水偏少。

Relationship between Activity of Transient Waves and Excessive/Deficit Summer Rain in Changjiang-Huaihe River Basin

Using the monthly precipitation of 160 stations in China from 1951 to 2000 year,deficit/excessive summer rain years of Changjiang-Huaihe River Basin(the Jianghuai region) are selected.It is found from the composite analysis of 500 hPa geopotential height anomaly that the blocking high near Okhotsk maintains steadily in excessive summer rain years,whereas the high ridge near Okhotsk is weakened in deficit summer years.The EliassenPalm flux are calculated to explore the reason for differences of the 500hPa circulation in middle and high latitudes between deficit and excessive summer rain years of Jianghuai.The analysis results of Eliassen-Palm fluxes indicate that in excessive summer rain years the forcing of transient waves to the mean flow makes patterns of zonal and meridional wind anomalies in favor of the maintenance of Okhotsk blocking high and thus the strengthening of the southward transfer of cold air,and excessive summer rainfall in Jianghuai,whereas in deficit summer rain years,the forcing of transient waves to the mean flow weakens the high ridge near Okhotsk and thus the weaking of the southward transfer of cold air,and deficit summer rainfall in Jianghuai.