Linear regression analysis of the influence of Western North Pacific tropical cyclones on their large-scale environment
The influence of Western North Pacific (WNP) tropical cyclones (TCs) on their large-scale environment,including 850 hPa relative vorticity,surface zonal wind,total column water vapor,outgoing longwave radiation (OLR),precipitation and sea surface temperature (SST),is investigated by lag regressing of the accumulated cyclone energy (ACE) index on monthly time scale,and the differences with that on weekly time scale is also discussed.The results show that (1) The zonal wind regressed by ACE on monthly time scale is more significant than that on weekly time scale both in intensity and scope.The frequent occurrence of TCs,especially the intense and long-lived near equator TCs,have a positive effect on stimulating or strengthening westerly anomalies to the south of TC activities'region to some extent.The long-lived and intense equatorial surface westerly anomalies can cause westerly wind bursts,and westerly wind bursts are believed to be a major factor during the occurrence and development of ENSO events.(2)On monthly time scale,more variables,such as OLR,precipitation and SST,exhibit El Ni(n)o type features than that on weekly time scale,which suggests that TC activities on monthly time scale are closely related to ENSO cycle.(3) After the genesis of TCs for one or two months,the drying and associated OLR increasing in the original region of TC activities can reduce the potential of TCs occurrence.Although the SST reduction by TC is small in spatial scale,it would expand to a large scale through adjustment mechanisms in ocean and atmosphere.In addition,as the feedback is lagged,the signals of TCs on their large-scale environment on monthly time scale are more significant.
NETL
NSTL
万方数据
维普
