Spatial and Temporal Characteristics of Various Cold Surges over China During 1962–2018

The cold surge (CS) is an extreme climate event that frequently affects China. By using a 0.25 degrees x 0.25 degrees gridded observation dataset provided by the China Meteorological Administration (CN05.1), this paper investigates the spatial-temporal characteristics of various CSs in China during 1962-2018. According to the duration and coverage area (CA), CSs are classified into the short-lived cold surges (SLCSs), the persistent cold surges (PCSs) and the extensive and persistent cold surges (EPCSs). They are also divided into the weak cold surges (WCSs), the strong cold surges (SCSs) and the super strong cold surges (SSCSs) based on the temperature drop (Delta T). The extreme cold surges (ECSs) are also defined and occur 38 times over 57 years. The total CSs and various CSs all display patterns of higher frequencies in the northeast and lower frequencies in the southwest. Northeast China and Inner Mongolia are frequently hit by various CSs, but the frequencies show overall downward trends in the regions during 1962-2018. The Delta T of the total CSs and ECSs both show significant decreasing trends in the whole of China from 1962 to 2018. From 1962 to 2018, the annual frequency and the Delta T of the total CSs both show decreasing trends. SLCSs and WCSs frequencies show overall increasing trends, but other kinds of CSs show overall decreasing trends. The annual frequencies of the total CSs and various CSs all have trend abrupt changes around 2000. The Delta T of ECSs shows a sharply increasing trend during 1962-2018. The total CSs and all kinds of CSs frequencies have a significant periodic oscillation. ECSs occur most in February. The total CSs and other kinds of CSs occur most in January. There are obvious differences between the multiyear average ECSs frequencies before 2000 and after 2000.