An Intense Midwestern Cyclone: Fine-scale Comparison of Model Analysis with TOMS Total Ozone Data

The fine-scale upper-tropospheric dynamics of an intense cyclone, which established new records for minimum sea level pressure in Iowa and Minnesota in November 1998, is investigated using TOMS total column ozone data and model analyses. Surprisingly complex organization is seen in both the meteorological data and the total ozone data, and both fields are in good agreement. Stratospheric air reached to within 2 km of the ground, perhaps aiding rapid intensification which soon followed. Later, ozone data support other meteorological data showing that stratospheric descent was generally confined to above about 600 hPa; significant positive potential vorticity at lower levels was most likely diabatically generated. Good agreement occurs between mesoscale features found in the model analyses and total column ozone fields, even for features with scales of a few hundred kilometers. Significant vertical structure is seen in the potential vorticity fields in the upper troposphere and lower stratosphere, and may have an impact on the development of algorithms to derive meteorological variables used in model data assimilation systems. Observations from this case suggest potential benefits in numerical weather prediction from the use of total column ozone data over data sparse regions, particulary if ozone data can be provided from a geostationary platform.