局地水汽异常引起的非绝热加热对2016/2017年中国南方暖冬的影响

基于NCEP/NCAR再分析资料, 利用气温异常的倾向方程分析2016/2017年中国华北地区(100~115 °E, 35~45 °N)、西南地区(85~102 °E, 22~33 °N)和南方地区(108~118 °E, 22~33 °N)的暖冬事件。结果表明西南和华北地区的平流作用占主导地位, 而2016/2017年冬季中国南方暖冬主要是非绝热加热引起的。进一步通过水汽收支平衡的分析表明, 局地水汽异常对2016/2017年中国南方暖冬有重要贡献, 而其中土壤的水汽贡献约占50%。可能的机制如下:大气中正的水汽异常引起辐射加热增多, 导致气温升高, 土壤的感热增大, 土壤温度升高, 潜热通量变大, 从而向大气的水汽输送增多, 更多的水汽将导致更高的温度。 

EFFECT OF DIABATIC HEATING INDUCED BY REGIONAL WATER VAPOR ANOMALIES IN 2016/2017 WARM WINTER OVER THE SOUTH OF CHINA

NCEP/NCAR reanalysis data are used to analyze a warm winter in 2016/2017 in three regions of China, i.e., North (100~115 °E, 35~45 °N), Southwest (85~102 °E, 22~33 °N) and South (108~118 °E, 22~33 °N), by analyzing the equation of air temperature budget. The results indicate that in the 2016/2017 warm winter event advection plays a main role over the north and southwest of China, but diabatic heating dominates over the south of China. Further analysis of moisture budget suggests that diabatic-heating-induced regional water vapor anomalies, about half of which come from soil, give great contribution to the 2016/2017 warm winter event over the south of China. A possible positive feedback mechanism is: positive water vapor anomalies increase radiation heat to warm the air, and then downward sensible heat flux increases soil temperature; as a result, larger upward latent heat flux leads to more water vapor, and then another cycle repeats.