The 2020 Summer Floods and 2020/21 Winter Extreme Cold Surges in China and the 2020 Typhoon Season in the Western North Pacific

China experienced significant flooding in the summer of 2020 and multiple extreme cold surges during the winter of 2020/21.Additionally,the 2020 typhoon season had below average activity with especially quiet activity during the first half of the season in the western North Pacific(WNP).Sea surface temperature changes in the Pacific,Indian,and Atlantic Oceans all contributed to the heavy rainfall in China,but the Atlantic and Indian Oceans seem to have played dominant roles.Enhancement and movement of the Siberian High caused a wavier pattern in the jet stream that allowed cold polar air to reach southward,inducing cold surges in China.Large vertical wind shear and low humidity in the WNP were responsible for fewer typhoons in the first half of the typhoon season.Although it is known that global warming can increase the frequency of extreme weather and climate events,its influences on individual events still need to be quantified.Additionally,the extreme cold surge during 16–18 February 2021 in the United States shares similar mechanisms with the winter 2020/21 extreme cold surges in China.

Global land-surface air temperature change based on the new CMA GLSAT data set

The China Meteorological Administration(CMA)has recently developed a new global monthly homogenized land-surface air temperature data set.Based on this data set,we reanalyzed the change in global annual mean land-surface air temperature(LSAT)during three time periods(1901–2014,1979–2014 and 1998–2014).The results show that the linear trends of global annual mean LSAT were 0.104°C/decade,0.247°C/decade and 0.098°C/decade for the three periods,respectively.The trends were statistically significant except for the period 1998–2014,the period that