CR prepress abstract   -  DOI: https://doi.org/10.3354/cr01725

ABSTRACT: Tornadoes are the most destructive meso-small scale strong convective weather on Earth. At present, however, the temporal change of tornadoes in a subcontinental region like China mainland is still controversial. Here, we report an analysis for the spatial-temporal pattern and long-term trend of tornadoes in China mainland from 1961 to 2013 based on a dataset of the national meteorological observational network. We show that there are total 1082 tornado days recorded by the national meteorological stations from 1961 to 2013, with the average occurrence frequency of 20.42 d/yr. Three high-frequency centers are concentrated in South China, East China, and Northeast China. Tornado mainly occurs in summer season, mostly in July and August. The annual mean tornado days in China mainland during 1961-1969 reach 43.89 d/yr, but the period 2010-2013 sees no tornado based on the station records. There is a highly significant decreasing trend of annual total tornado days during 1961-2013, with a rate of -10.00 d/10yr. The decreasing trend in summer is the most significant. We find that the decadal decrease in a few of atmospheric variables, including convective available potential energy (CAPE), 0-6km vertical shear and low-troposphere relative humidity, is closely associated with the tremendous drop of tornado days.