Gravity waves drive the atmospheric circulation and have substantial impact on weather and climate. Satellite instruments offer excellent opportunities to study gravity waves on a global scale. Here we discuss stratospheric gravity wave observations based on 4.3 micron radiance measurements of the Atmospheric Infrared Sounder (AIRS) aboard NASA's Aqua satellite and the Infrared Atmospheric Sounding Interferometer (IASI) aboard the European MetOp satellites. A nine-year record (2003-2011) of AIRS data was used to identify "hotspots" of gravity wave activity on a global scale. The hotspots are classified in terms of source mechanisms such as orography and convection. Our study reproduces well-known hotspots of stratospheric gravity wave activity, e.g., the Andes or the Scandinavian Mountains. However, the high horizontal resolution of the AIRS also allows us to locate small-scale hotspots, which are partly unknown or poorly studied so far. While AIRS has been used successfully in many previous gravity wave studies, IASI data have not been exploited so far. We present a first intercomparison of stratospheric gravity wave observations of AIRS and IASI based on a five-year period of measurements (2008-2012). Case studies showed that AIRS and IASI provide a clear and consistent picture of the temporal development of individual gravity wave events. Statistical comparisons show similar spatial and temporal patterns of gravity wave activity. Combined long-term records from different nadir sounders are an exciting prospect for future studies of stratospheric gravity wave activity.

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*email: l.hoffmann@fz-juelich.de
*Preference: Oral