The anomalous circulation in the southern hemisphere stratosphere during spring 1987



The general circulation of the Southern Hemisphere stratosphere during 1987 is analyzed based on National Meteorological Center analyses, and contrasted to a climatological average constructed from the years 1980-1986. The polar lower stratosphere in spring 1987 is substantially colder than the climatology, with zonal mean differences of order 16K near 50 mb in November. Substantially warmer temperatures (near 8K) are observed in these data in the polar upper stratosphere coincident with the lower level cooling. Associated with the strong cooling in the lower stratosphere is a delay in the spring final warming during 1987 of approximately 20 days (compared with climatology). Although the majority of the observed cooling probably results from the record low ozone levels observed during 1987, the observed planetary wave driving during 1987 is substantially below climatological levels, also contributing to a colder pole.