Influence of Obliquely Propagating Monsoon Gravity Waves on Southern Polar Summer Mesosphere after Stratospheric Sudden Warmings in Winter Stratosphere

Abstract:

Oblique propagation of gravity waves (GWs) refers to the latitudinal propagation of GWs (or vertical propagation away from their source) from the low latitude troposphere to the polar mesosphere. This propagation is ignored in current gravity wave parameterization schemes, but may be an important component of the global dynamical structure of the mesosphere. Before including this process in models, observational analysis is needed to quantify this oblique propagation of GWs and its effect on the atmosphere. These effects are believed to be especially important in the polar summer mesosphere. Previous studies have revealed a high correlation between observations of the momentum flux from monsoon GWs (GWMF) and Polar Mesospheric Clouds (PMCs) in northern hemisphere. We report an analysis of the oblique propagation in the southern hemisphere using data from AIM/CIPS (PMCs), TIMED/SABER (GWMF), DPR/TRMM (precipitation), AVHRR/NOAA (outgoing radiation) and MERRA-2 model (wind). We compare PMCs seasons in both hemispheres and their correlation with GWMF from deep convection regions, identified with precipitation and radiation information. We also explore the interhemispheric coupling mechanism by looking at the effect of Stratospheric Sudden Warmings (SSWs), occurring in the opposite winter stratosphere, on propagation of GWs in summer southern hemisphere. This focus allows us to improve our understanding of the dynamics in summer southern hemisphere, during PMCs and monsoon GWs seasons, in order to refine gravity wave schemes.