Polar atmospheric circulation and chemistry of recent (1957‐1983) south polar precipitation

Abstract

In this paper, we present a detailed study of Na, Cl, and NO3 concentrations in the south polar snow layers covering the 1957‐1983 time period. Our data point to a trend of the Na winter values which suggest a weaker poleward transport within the troposphere since 1980. The NO3 profiles exhibit generally maxima in summer. However, as an exception to this rule, we observe additional maxima during the springs of 1982, 1975 or 1976, 1973 or 1974, and to a lesser extent in 1959. These unusual patterns of the seasonal NO3 deposition correspond to years during which the lower stratosphere was very cold. This coincidence provides an indirect support for the hypothesis of a denitrified stratosphere by polar stratospheric clouds (PSCs). Due to inherent problems in studying seasonal variations in the south polar snow, these results have to be taken with some caution. Nevertheless, if confirmed by additional measurements and extended to the present, such studies of south polar precipitation will be very useful to examine changes of the southern hemisphere circulation pattern and to provide a long term record of polar stratospheric temperature.