An ozone climatology based on ozonesonde and satellite measurements

Abstract

An ozone climatology is presented, based entirely on ozone observations over the target period 1980-1991. The climatology gives zonal mean ozone values, as well as the corresponding interannual standard deviation, for 17 zonal bands (80°S-80°N) at 19 pressure levels (1000-0.3 hPa), for each month of the year. It is intended mainly for climate simulations with general circulation models (GCMs). For the troposphere and lower stratosphere (1000-10 hPa) the climatology is compiled from ozonesonde observations of 30 ozonesonde stations located around the world. To account for tropospheric longitudinal variability within a zonal band, a data set giving tropospheric total ozone values between 50°S and 50°N is used. For stations within this latitude range the tropospheric profile is scaled with a factor derived from this data set to make it more representative of the zonal mean. Consequently, the corrected profiles of the individual stations are combined within each zonal band, using weighted averaging. These zonal profiles are then attached to zonal monthly mean SBUV-SBUV/2 (solar backscattered ultraviolet) observations in the stratosphere (30-0.3 hPa). Three overlap layers, at 30, 20, and 10 hPa, give an indication of how well these two data sets match. Where possible, the integral of the combined ozone profiles is made consistent with total ozone mapping (TOMS) profiles, by applying a correction factor to the ozonesonde part of the profile, derived from TOMS minus the integrated SBUV-SBUV/2 profile. The resulting climatology is compared with three other ozone climatologies: the predecessor of this one, a climatology compiled by the State University of New York, and a climatology used in the GCM at the Max Planck Institute in Hamburg, Germany. Apparent improvements are better consistent with TOMS (compared with the first climatology) and more realistic ozone values in the tropics and polar regions (compared with the first and second climatologies). There is an overall strong improvement compared with the third climatology, which was generated from an analytical formula and old ozone observations in the 1970s. A unique further advantage of the current climatology is the accompanying standard deviation climatology, giving an indication of the natural variability and reliability of the mean ozone values. Copyright 1998 by the American Geophysical Union.