Equatorial Kelvin wave signatures in ozone column measurements from the Global Ozone Monitoring Experiment (GOME)

This study investigates tropical Kelvin wave signatures in the total ozone column data from the Global Ozone Monitoring Experiment (GOME) instrument. A new approach for spectral analysis is introduced by generalizing an unequally spaced data technique from one to two dimensions. This enables the handling of satellite data containing gaps. The simple statistical behavior of the method furthermore allows an easy determinination of the statistical significance of any observed spectral features. Seven years of GOME data (1995–2002) have been analyzed in which we have identified three periods of high Kelvin wave activity in 1996, 1998, and 2000. The periods are in conjunction with westward equatorial zonal winds at 30 hPa and show eastward propagating waves 1–2 with periods of ∼12–15 days. The induced Kelvin wave signatures in the ozone concentrations are around 2–4 DU peak-to-peak and can be attributed to “slow” Kelvin waves. The results are shown to be significant. Our study provides an important contribution to the study of Kelvin waves by introducing the bidimensional unequally spaced data spectral analysis and is the first to demonstrate the potential of the GOME ozone data set to contribute to a global description of equatorial Kelvin wave activity.