不同冷暖背景下影响云南冬季温度异常的环流特征OACSTPCD

Using the monthly temperatures data of 122 stations in Yunnan Province from 1961 to 2019,the ERA5 reanalysis data,and atmospheric circulation indices data,the characteristics of winter temperature variation characteristics in Yunnan were analyzed.Results indicate that there is a very significant warming trend for winter temperatures in Yunnan,with an abrupt warming in 1996.Further analysis of the circulation differences between anomalously cold and warm years during cold and warm periods reveals significant differences in the atmospheric circulation during cold(warm)events in different periods,indicating that the characteristics of strong cold air activity in eastern East Asia during cold events in the warm periods(WC)are more significant than those of cold events in the cold periods(CC),while the characteristics of weak cold air and strong southwest warm-wet airflow during warm events in the cold periods(CW)are more significant than those of warm events in the warm periods(WW).The warm period requires stronger cold air activity to generate the cold event,whereas the cold period requires stronger southwest warm-wet airflow from the tropics to trigger the warm event.During both cold and warm periods,the height field of the plateau and the strength of the Indo-Burmese trough are major indications of the mean winter temperatures in Yunnan.