Antarctic dehydration 1998–2003: Polar Ozone and Aerosol Measurement III (POAM) measurements and Integrated Microphysics and Aerosol Chemistry on Trajectories (IMPACT) results with four meteorological models

We present Polar Ozone and Aerosol Measurement III (POAM) measurements of Antarctic dehydration from 1998 to 2003 and compare these measurements with calculations performed with the Integrated Microphysics and Aerosol Chemistry on Trajectories (IMPACT) microphysical model. Previous work has shown that while dehydration is not very sensitive to reasonable changes of microphysical parameters, it is very sensitive to changes in temperature. We shall therefore compare dehydration as measured by POAM with IMPACT model runs based on four meteorological analyses: United Kingdom Meteorological Office (UKMO), European Centre for Medium-Range Weather Forecasts (ECMWF), National Centers for Environmental Prediction Climate Prediction Center (NCEP-CPC), and NCEP reanalysis. For the years 1998–2000, the agreement between the minimum water vapor found in the POAM measurements and that from all of the model runs is always within 0.5 ppmv. The disagreement between POAM and some of the models is larger in the years 2001–2003, growing as large as ~1 ppmv, but the agreement between the minimum POAM water vapor and the water vapor calculated using the NCEP reanalysis is always within 0.2 ppmv. If we infer a temperature bias from the difference between the NCEP reanalysis model runs and the POAM minimum water vapor measurements, we find that this temperature bias is <0.5 K for each of the 6 years from 1998 to 2003, but it is often larger for the other meteorological analyses.