Southern Hemisphere extra-tropical gravity wave activity is examined using simulations from a free-running middle atmosphere general circulation model called Kanto which contains no gravity wave parameterizations. The total absolute gravity wave momentum flux (MF) and its intermittency, diagnosed by the Gini coefficient, are examined during January and July. The MF and intermittency results calculated from the Kanto model agree well with results from satellite limb and super-pressure balloon observations. The analysis of the Kanto model simulations indicates the following results. Non-orographic gravity waves are generated in Kanto in the frontal regions of extra-tropical depressions and around tropopause-level jets. Regions with lower (higher) intermittency in the July mid-stratosphere become more (less) intermittent by the mesosphere due to lower-level wave removal. The gravity wave intermittency is low and nearly homogeneous throughout the SH middle atmosphere during January. This indicates that non-orographic waves dominate at this time of year, with sources including continental convection as well as oceanic depressions. Most of the zonal mean MF at 40 -- 65S in January and July is due to gravity waves located above the oceans. The zonal mean MF at lower latitudes in both months has a larger contribution from the land regions but the fraction above the oceans remains larger.

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*email: simon.alexander@aad.gov.au
*Preference: Poster