Analysis of the December 2016 Atmospheric Circulation and Weather
The main characteristics of the general atmospheric circulation in December 2016 are as follows： There were two polar vortex centers in the Northern Hemisphere with weaker pressure in the center than normal year. The circulation presented the troughridgetrough pattern in the middlehigh latitudes of Eurasia. The south branch acted weakly, located near 90°E essentially. The subtropical high was stronger than normal years. The monthly mean precipitation was 11.5 mm, 9.5% more than normal. Besides, the monthly mean temperature was -0.7℃, 2.5℃ higher than normal （-3.2℃）， which is the maximum value for the corresponding periods since 1961. During this month, two cold air processes, two major rainfall processes and three largescale foghaze weather processes occurred, of which the foghaze event from 16 to 21 December was recorded as the most extensive, the longest lasting and the most severe foghaze weather process in 2016.