How well can satellite retrievals resolve the vertical structure of planetary waves?

In this study we examine the ability of satellite retrievals to resolve the vertical structure of planetary waves, using a model. The vertical structure of the waves contains basic information on their propagation characteristics. By relating observed vertical wave structure to the observed basic state in the stratosphere, we can examine the applicability of linear propagation theory to the waves. In particular, we are interested in explaining daily time scale variations of vertical structure. It is essential for our study to understand the effect of the coarse resolution of satellite retrievals on these observations. Past studies that have tested the ability of a retrieval algorithm to reproduce a temperature profile have mostly emphasized the ability to simulate the vertical structure of the temperature field, and not wave structures, which are deviations from the zonal mean.

In the present study, we calculate the radiances that a virtual satellite sitting at the top of our model atmosphere sees, and invert them to obtain retrieved temperature fields. The comparison to the model temperatures suggests that the largest errors occur above a certain height and on small scales, but since most waves have quite large vertical wavelengths, the retrievals are able to resolve their general features quite well. We also identify dynamic situations in the real atmosphere which are more prone to retrieval errors. These are mostly relevant to summer or to the breakup of the polar vortex.