Analysis of the February 2018 Atmospheric Circulation and Weather
The main characteristics of the general atmospheric circulation in February 2018 are as follows. There were two polar vortex centers in the Northern Hemisphere and the stronger one was in the Western Hemisphere. The circulation at middle-high latitudes of the Eurasian showed a three-wave pattern, and the degree of meridionality was lower than normal. The western Pacific subtropical high was close to the climatological normal, and the Bay of Bengal trough was weaker than normal. Cold air processes attacked China frequently in February. The cold air was stronger in early February, once across the whole country and another time over northern China. The monthly mean temperature was -2.0℃, lower than normal by 0.3℃. The amount of precipitation in first half of the month was less than normal, while continuous rainfall happened in the second half of the month. Also, a snowstorm event hit Northeast China at the end of the month. The monthly mean precipitation amount was 8.1 mm, 53% less than normal. In addition, the severe long-time fog event appeared at Qiongzhou Strait and sand-dust weather appeared in Northwest China firstly this year.