The stratospheric index-of-refraction for planetary wave propagation

The index-of-refraction (IOR) is a primary control for the direction of planetary wave propagation in the stratosphere. We have used 30-years of the GMAO Modern Era Retrospective-analysis for Research and Applications (MERRA) analyses to calculate a climatology of the index-of-refraction for planetary waves. This climatology reveals a negative IOR slightly north of the subtropical jet during the mid-winter to spring period. This region is found to be strongly correlated with temperatures and wave activity in the stratosphere. We will discuss this curious region, show the relationship to other variables, and show how it relates to mixing of trace species. In addition, we will show how this region will change in the future.