Coherent ozone‐dynamical changes during the southern hemisphere spring, 1979–1986

Abstract

National Meteorological Center (NMC) data is used in conjunction with Total Ozone Mapping Spectrometer (TOMS) data to study seasonal and interannual variability during the southern hemisphere springs of 1979 through 1986. Virtually perfect spatial correlation is found between October average lower stratospheric temperatures and total ozone for each year. The constant of proportionality between total ozone and lower stratospheric temperature varies significantly (but not systematically) over the years 1979 through 1986 and is in approximate agreement with that calculated for adiabatic air parcel motion. Spatial patterns of change in total ozone over 1979–1986 show remarkable agreement with lower stratospheric temperature changes; in addition to pronounced decreases in the Antarctic region, a slight increase of both is also observed at 50°S to the west of South America. In addition to ozone variability correlated with observed temperature changes, there is a substantial decline not linearly related to the observed temperature change. Spatial and temporal characteristics of interannual changes in NMC temperatures are analyzed in some detail. Extensive comparisons are made between radiosondes and NMC analyses, showing good agreement of monthly means. Trend analyses of zonal mean temperatures over the period 1979–1986 show strongest coolings (−0.7°K/yr) during October in the 10‐ to 100‐mbar region. Cooling patterns are zonally asymmetric, so that seasonal or zonal mean temperature changes underestimate local October changes. Between October 1979 and October 1985 (two extreme years), maximum local temperature changes of 18° and 22°K are observed at 70 and 30 mbar, respectively (coincident with a local 160 Dobson unit total ozone decrease). Interannual variations and trends of stationary wave 1 heat flux in the spring lower stratosphere are found to be coherent with the observed temperature and ozone fluctuations (stationary wave 1 dominates the southern hemisphere spring stratospheric eddy fluxes). In the 1000‐ to 100‐mbar regions, where transient wave fluxes are dominant, large differences between NMC and European Centre for Medium Range Weather Forecasts analyses preclude trend analyses.