Direct retrieval of wind from Total Ozone Mapping Spectrometer (TOMS) data: Examples from FASTEX

The quantitative relationship between ozone and potential vorticity, and hence balanced wind and temperature, is examined using observations collected for a one-month period by the total ozone mapping spectrometer (TOMS). Ozone data are compared with Ertel potential vorticity (PV) integrated vertically from 500 to 50 mb, obtained from the NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research) reanalysis archive. By performing a simple time filtering we isolate synoptic-scale transients in the ozone and PV. We show that the previously reported high correlation between PV and ozone is actually variable from day to day. The correlation also shows strong latitudinal dependence, with essentially no correlation in the tropics and high correlation in middle latitudes. A method is introduced to derive a three-dimensional PV representation from ozone data and a background field taken from the reanalysis data. PV-inversion methods are then used to recover balanced winds and temperatures and geopotential heights which may be compared to the analysed fields. Results suggest that many of the upper-tropospheric synoptic-scale wind perturbations may be recovered from the ozone data. A systematic error in the retrieval method used here is the underestimation of the strength of upper-level ridges, corresponding to an excess of vertically integrated ozone compared with integrated PV. We discuss reasons for this difference.