摘要
In this study,the authors analyzed the associations between the Arctic Oscillation(AO)and the tropical Indian Ocean(TIO)intertropical convergence zone(ITCZ)in boreal winter for the period 1979–2009.A statistically significant AO-TIO ITCZ linkage was found.The ITCZ vertical air motion is significantly associated with the AO,with upward(downward)air motion corresponding to the positive(negative)AO phase.The Arabian Sea anticyclone plays a crucial role in linking the AO and the TIO ITCZ.The Arabian Sea vorticity is strongly linked to high-latitude disturbances in conjunction with jet stream waveguide effects of disturbance trapping and energy dispersion.During positive(negative)AO years,the Arabian Sea anticyclone tends to be stronger(weaker).The mean vorticity over the Arabian Sea,averaged from 850hPa to 200 hPa,has a significant negative correlation with AO(r=0.63).The anomalous anticyclone over the Arabian Sea brings stronger northeastern winds,which enhance the ITCZ after crossing the equator and result in greater-than-normal precipitation and minimum outgoing long-wave radiation.
In this study,the authors analyzed the associations between the Arctic Oscillation （AO） and the tropical Indian Ocean （TIO） intertropical convergence zone （ITCZ） in boreal winter for the period 1979-2009.A statistically significant AO-TIO ITCZ linkage was found.The ITCZ vertical air motion is significantly associated with the AO,with upward （downward） air motion corresponding to the positive （negative） AO phase.The Arabian Sea anticyclone plays a crucial role in linking the AO and the TIO ITCZ.The Arabian Sea vorticity is strongly linked to high-latitude disturbances in conjunction with jet stream waveguide effects of disturbance trapping and energy dispersion.During positive （negative） AO years,the Arabian Sea anticyclone tends to be stronger （weaker）.The mean vorticity over the Arabian Sea,averaged from 850 hPa to 200 hPa,has a significant negative correlation with AO （r =-0.63）.The anomalous anticyclone over the Arabian Sea brings stronger northeastern winds,which enhance the ITCZ after crossing the equator and result in greater-than-normal precipitation and minimum outgoing long-wave radiation.
基金
supported by Global Change,Environmental Risk and Its Adaptation Paradigms(2012CB955401)
the Chinese Academy of Sciences Strategic Priority Research Program(XDA05110203)
supported by the National Natural Science Foundation of China(41375071)
作者简介
Corresponding author： GONG Dao-Yi, gdy@bnu.edu.cn
