Winter Month-to-month Evolution Of Decadal Changes In The Arctic Stratosphere And Its Mechanism Analysis

Firstly,using ERA-Interim,JRA-55 and MERRA-2 three sets of reanalysis data,the decadal changes of stratospheric temperature and zonal wind field in different winter months of ozone depletion period(1980-2000)and the ozone recovery period(2001-2018)were analyzed respectively.And the winter month-to-month evolution characteristics in the two periods were further analyzed by ozone concentration and Northern Hemisphere Annular Mode(NAM)index.Then the dynamic mechanism of the month-to-month evolution was explained through calculating the decadal changes of Eliassen-Palm(EP)flux and its divergence and the residual circulation.Finally,the reasons for the temperature change in the ozone depletion period and the ozone recovery period were discussed from the aspects of dynamic heating and diabatic heating.The main conclusions are summarized as follows:(1)From 1980 to 2000,the decadal changes of temperature and zonal wind in December and February were completely opposite,while January was an obvious transition period,and the changes of both were weaker.From 2001 to 2018,the winter months showed similar changes,in which the temperature decreased and the zonal wind accelerated,but there were differences in the intensity and region.Therefore,the decadal changes of stratospheric temperature and zonal wind field showed different month-to-month evolutions during the ozone depletion and recovery periods.(2)By calculating the decadal changes of EP flux and its divergence and the residual circulation,the relationship between the planetary waves and the stratospheric meteorological field was analyzed.It was found that the decadal changes of EP flux and its divergence and the meteorological field have a good matching relationship in each month of winter for 1980-2000.But for 2001-2018,the relationship only performed well in December and February,the planetary wave and the residual circulation do not match the cooling and acceleration of the polar stratosphere in January.Therefore,during the ozone depletion period,the month-to-month evolution of temperature and zonal wind field can be better explained through the wave-current interaction theory.While for the ozone recovery period,the change of the meteorological field in December and February can be explained purely from the perspective of dynamics,but the change in January cannot be explained by the same way.(3)We calculate the contributions of dynamic and diabatic heating to the temperature change respectively at 100 h Pa in the polar region.It was found that from 1980-2000,the dynamic heating played a leading role in December,and the dynamic heating and diabatic heating contributed equally in January,while dynamic cooling plays a leading role in February.From 2001-2018,the dynamic cooling plays a leading role to temperature decreasing in December,while the diabatic cooling plays a leading role in January,the contribution of dynamic cooling and diabatic cooling is equivalent in February.Therefore,the temperature change is mainly determined by the dynamic effect in the ozone depletion period,while for the period of ozone recovery,the contribution of diabatic heating to the temperature change at 100 h Pa begins to be important,especially in January when the diabatic cooling becomes the dominant factor.