Spatial and temporal variations of monthly mean total columnar ozone derived from 7 years of BUV data

Abstract

The monthly mean total columnar ozone fields are represented by ninth degree spherical harmonic models. Spatial spectra are defined in terms of simple analytic expressions which represent the rms value of each spherical harmonic coefficient. These spectra are combined with estimation theory techniques to develop a realistic error analysis that accounts for errors due to nonglobal coverage. Over the 7‐year data set, systematic variations are represented by an annual, semiannual, and biennial model, along with secular trends where required. The annual component of zonal mean ozone compares favorably with previous results based on Dobson data. The semiannual term is shown to be the dominant variation near the South Pole. In the tropics, the results support the theory that enhanced Hadley cell circulation is responsible for the biennial variation in zonal mean ozone. Amplitude and phase variations for longitudinal waves 1, 2, and 3 are presented. In the northern hemisphere, these waves reinforce in space and time during the period of high poleward transport of ozone. In the southern hemisphere, the wave 2 and 3 components are much smaller, and wave 1 maximum amplitude occurs in September and October.