Inter-hemispheric coupling in PMC observations and in models

Polar mesospheric clouds (PMC) are excellent indicators for the state of the summer mesopause region. We investigate coupling processes in the atmosphere using PMC observations. The variability in PMC properties observed by the Aeronomy of Ice in the Mesosphere (AIM) and Odin missions are correlated with temperature measurements from the Microwave Limb Sounder (MLS) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument and wind data from the Goddard Earth Observing System (GEOS). As a complement to the measurements, model data from the Canadian Middle Atmosphere Model (CMAM), the Whole Atmosphere Community Climate Model (WACCM), the Kühlungsborn Mechanistic Climate Model (KMCM) and The Navy Operational Global Atmospheric Prediction System (NOGAPS) are shown. Clear evidence of inter-hemispheric coupling is found in inter-seasonal as well as intra-seasonal variability, indicating that the variability in PMCs, and thus the summer mesopause region is driven, to a significant extent, by planetary wave activity in the winter troposphere and stratosphere.