Effects Of Stationary And Transient UTLS Ozone Transport On The Ozone Valley And Its Extremely Strong Events Over The Tibetan Plateau In Summer

In this paper,we use the ERA-Interim reanalysis data of the European Centre for Medium-Range Weather Forecasts to define the characteristics of the extreme events in the Ozone Valley over the Tibetan Plateau(OVTP).The Lorenz circulation decomposition method combined with the ERA-Interim reanalysis data and the MLS satellite observation data to study the characteristics of ozone transport in the summer UTLS and the upper stratosphere.The analysis of stationary and transient transport conditions to further discuss the role of ozone transport in the extreme events of the Ozone Valley over the Tibetan Plateau in summer,with the following main conclusions:(1)In the UTLS and the upper stratospheric ozone transport,the Ozone Valley over the Tibetan Plateau is strengthened in summer,both of which are the main functions of stationary transport.And the transient transport effect is weak,which makes the ozone valley slightly weakened.The combination of stationary and transient transport,from the zonal and meridional directions,the zonal ozone transport makes the ozone valley stronger and the intensity is strong,and the meridional ozone transport is weakened and the intensity is weak.(2)In the summer UTLS region,the STu2 item of the stationary zonal ozone transport has the strongest effect on the ozone valley,which strengthens the ozone valley;the STm2 term of the stationary meridional transport is the strongest,and makes ozone valley weakened.The TTu2,TTu3 and TTu4 items of the planetary-scale transient zonal ozone transport are all strong.The TTv3 of transient meridional ozone transport has a greater effect,which strengthens the ozone valley.The role of TTu3 and TTu4 in weather-scale transient ozone transport is obvious,and both strengthen the ozone valley.TTv3 and TTv4 are more active in transient meridional ozone transport in weather scales.In summer,the STu2 term of the stationary zonal ozone transport in the upper stratosphere has the strongest effect on the ozone valley,which strengthens the ozone valley.The STv2 term of the stationary meridional transport is the strongest,mainly makes the upper part of the ozone valley weakened.The role of TTu3 in transient zonal transport is stronger,which slightly strengthens the lower part of the ozone valley.All of three items of the transient meridional ozone transport has strengthened most of the ozone valley,but the intensity is small.(3)Extreme strong OVTP frequently occurs in summer and autumn,and it appears mostin October;Ordinary strong OVTP frequently occurs in spring and summer,with the most occurrence in July;Extreme weak OVTP frequently occurs in autumn and winter,with the most occurrences in December;Ordinary weak OVTP frequently occurs in winter,with the most occurrences in January.Trends in extreme OVTP are significant,while trends in ordinary events are not significant.Extreme strong OVTP has increased significantly.Extreme weak OVTP has decreased significantly.Area and strength of extreme strong OVTP is the largest in autumn and reach the maximum in October;Ordinary strong OVTP is the highest in summer and peak in July;Extreme weak OVTP is small in spring and summer and reach a minimum in April;Ordinary weak OVTP is small in spring,summer and autumn,and reach minimum values in April(October).The significant trends of area and the strength of extreme(ordinary)strong OVTP;On the other hand,the significant trends of area and the strength of extreme(ordinary)weak OVTP.(4)In the summer UTLS region,the stationary zonal and meridional transport in the extreme strong events of the Tibetan Plateau have little change compared with the summer climatic transport characteristics,and the distribution characteristics and intensity are slightly different,but the effect of transient transport has obvious changes,especially the TTv4.The effect is very distinct,which makes the ozone valley obviously strengthened,and in the transport of summer extremely strong events,the role of weather-scale transient transport has been strengthened,and the impact has been significantly increased.