南海夏季风爆发与华南前汛期锋面降水异常变化的联系

利用1958-2000年NCEP/NCAR再分析日平均资料、中国气象局气候中心常规地面观测日降水资料,分析南海夏季风爆发异常情况下大气结构的变化特征,讨论华南冷空气活动、前汛期锋面降水情况与南海夏季风爆发异常之间的关系。结果表明:①南海夏季风爆发日期的异常变化主要取决于低层纬向风变化。②200 hPa以下对流层温度经向梯度逆转较早(晚),并且有(无)从上往下逐渐传播的变化趋势,则南海夏季风爆发偏早(晚)。③华南春季冷空气活跃(不活跃),降水偏多(偏少),南海季风爆发偏早(晚)。④综合提出了一个关于华南冷空气活动、锋面降水与夏季风爆发之间关系的物理概念模型。

Relationship between the Onset of the South China Sea Summer Monsoon and Abnormal Variations of frontal Precipitation during the First Rainy Period in South China

The daily NCEP/NCAR reanalyzed data and daily rainfall data during 1958-2000 from the National Climate Center of China Meteorology Administrator are used to analyze dynamic and thermodynamic characteristics under the abnormal onset of South China Sea Summer Monsoon. Relationships among the cold air activity in South China, precipitation in the yearly first rainy period and abnormal onset of the South China Sea Summer Monsoon are explored. The results indicate: 1) the abnormal change of onset dates of the South China Sea Summer Monsoon is mostly decided by zonal wind. 2) The early (late) onset of the South China Sea Summer Monsoon is related to the early (late) reversal of the troposphere temperature meridional gradient under 200 hPa and the trend transmitting downwards. 3) The more active cold air is in spring and the more precipitation there is in South China, the earlier the onset of the South China Sea Summer Monsoon occurs. 4) A synthetic physical concept model about the relationships among South China cold air activity, precipitation in the yearly first rainy period and anomalous onset of the South China Sea Summer Monsoon is presented.