Definition and characteristics of the south edge of the subtropical winter monsoon in East Asian

Based on observational daily data of 730 meteorological stations in China, the south edge of the subtropical winter monsoon is defined according to relevant criterion and its variation characteristics are analyzed. Results show that this south edge has obvious inter-annual variation characteristics and shows a northward moving tendency as a whole, but since the 21 st century it has moved southwards and date of the south edge entering winter becomes earlier. Wind fields of the anomalously northward south edge of the subtropical winter monsoon in East Asia has an obvious southerly wind component which prevents cold air from moving southward. The index of this south edge and winter temperature has a positive correlation. Climate warming might be the main reason for the northward movement of the south edge of the subtropical winter monsoon.

东亚副热带冬季风南边缘的确定及其变化特征

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。