东亚副热带冬季风南边缘的确定及其变化特征

Determination on the Boundary Belt of Subtropical Winter Monsoon in East Asia and Its Variance Characteristic

利用国家气候中心整编的中国730个测站逐日气温资料,基于冬季的划分标准定义了副热带冬季风南边缘并分析其变化特征。结果表明,副热带冬季风南边缘存在明显的年际变化特征,年代际尺度上虽总体呈现出北移,但进入21世纪后有明显的向南扩展、入冬时间提前的趋势。东亚副热带冬季风南边缘异常偏北年的风场在大陆上有显著的偏南风分量,不利于冷空气南下。定义的东亚副热带冬季风南边缘指数与冬季气温呈一致的正相关,气候变暖可能是冬季风南边缘偏北的主要原因。

Based on the observational data at 730 stations in China, the boundary belt of the subtropi- cal winter monsoon are defined according to the range of the south boundary line which the stations enter winter. The results show that the interannual change characteristics of south boundary of the subtropical winter monsoon in East Asia appear a tendency with moving northward, but it has moved southward in 21〈 century and the date of south boundary belt entering winter become earlier. It has southward wind in anomalous northward year of the boundary belt of subtropical winter monsoon in East Asia and blocks the cold air moving southward. The correlation coefficient between the south boundary of subtropical winter monsoon and air temperature in winter is positive. It is the possible main reason that the influence globe warming on the northward of south boundary of the subtropical winter monsoon.