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

Abstract

Polar mesospheric cloud (PMC) observations have revealed that interannual variability near the polar summer mesopause can be forced by planetary wave activity in the winter stratosphere. We use data from the Aeronomy of Ice in the Mesosphere (AIM) satellite to investigate coupling between the Arctic winter stratosphere and PMC variability in the Antarctic summer of 2007-2008. We find a high correlation between zonal mean PMC frequency and Arctic winter zonal mean winds from the Goddard Earth Observing System, as well as Microwave Limb Sounder zonal mean temperatures. The time lag between changes in the winter stratosphere and the connected response in PMCs varies from 2 to 8 days. We suggest that the differences in lag times are related to the evolution of cloud altitudes throughout the season. The results here are the first to show evidence for intra-seasonal PMC variability forced by interhemispheric coupling. Copyright 2009 by the American Geophysical Union.