Vertical structure of Convectively Coupled Equatorial Waves (CCEWs) during Boreal Summer and Winter

[摘要] Atmospheric variability in the tropics on the daily to intraseasonal timescale is often related to convectively coupled equatorial waves (CCEWs), including Kelvin, MRG, ER, and TD-type waves. This study aims toanalyze the observed vertical structures of the CCEWsduring boreal summer and winter fromthe NCEP-DOE reanalysis dataset. Consistent with a linear wave theory, the vertical structure of CCEWs is characterized by a distinctive phase tilt, indicatinga distinct direction of wave energy propagation. The vertical structure of Kelvin, MRG and ER waves is signified by westward phase tilts with height, especially in the upper troposphere when the waves become dry (i.e. there is noeffect of moisture), while in the lower troposphere, the phase tiltsdeviatesignificantly from the linear wave theory, whenthe waves become moist. On the other hand, the TD-type waves exhibit a perpendicular, baroclinic structure with height. The vertical structures of the Kelvin, MRG and TD-Type waves are more clearly observed during boreal summer, while ER waves are more observed during boreal winter. This is consistent with the increasing wave amplitudesdue to a stronger wave sourceduring those periods. Future studies are still required in order to understand how the vertical modulation of CCEWs on RH and wind fields can be used to better improve weather predictions in the tropics.

[发布机构] Department of Geophysics and Meteorology, Bogor Agricultural University (IPB), Indonesia^1;Department of the Geophysical Sciences, University of Chicago, Chicago, United States^2

[学科分类] 环境科学（综合）

[关键词] Atmospheric variability;Equatorial waves;Linear wave theory;Lower troposphere;Upper troposphere;Vertical modulation;Vertical structures;Weather prediction