Inter-annual variation of gravity waves in the Arctic and Antarctic winter middle atmosphere

High latitude, middle atmospheric (28-80 km) gravity wave observations from the Microwave Limb sounder (MLS) on the Upper Atmosphere Research Satellite (UARS) are available during five Arctic and Antarctic winters between 1991 and 1997. Newer data from NOAA Advanced Microwave Sounding Unit (AMSU) instruments have been introduced recently, in order to extend the gravity wave measurements from 1998 to present. Analyses of MLS and AMSU data show substantial inter-annual variability in both magnitude and spatial patterns of gravity wave activity at both Arctic and Antarctic latitudes.