Intra-seasonal variability of polar mesospheric clouds due to inter-hemispheric coupling

摘要

Polar mesospheric cloud (PMC) observations haverevealed that interannual variability near the polar summermesopause can be forced by planetary wave activity in thewinter stratosphere. We use data from the Aeronomy of Icein the Mesosphere (AIM) satellite to investigate couplingbetween the Arctic winter stratosphere and PMC variabilityin the Antarctic summer of 2007-2008. We fmd a highcorrelation between zonal mean PMC frequency and Arcticwinter zonal mean winds from the Goddard EarthObserving System, as well as Microwave Limb Sounderzonal mean temperatures. The time lag between changes inthe winter stratosphere and the connected response in PMCsvaries from 2 to 8 days. We suggest that the differences inlag times are related to the evolution of cloud altitudesthroughout the season. The results here are the first to showevidence for intra-seasonal PMC variability forced by inter-hemispheric coupling.