Kelvin wave signatures in ECMWF meteo fields and Global Ozone Monitoring Experiment (GOME) ozone columns

Abstract

This study investigates the vertical structure of the Kelvin wave signals previously found in total ozone column measurements from the Global Ozone Monitoring Experiment (GOME) instrument. For this, zonal wind and temperature measurements from the European Centre for Medium‐Range Weather Forecasts (ECMWF) Re‐Analysis data set are analyzed by using the same bidimensional spectral method as was used to analyze the GOME total ozone columns. These fields are available on 60 levels from the surface to 0.1 hPa. For the three high Kelvin wave activity periods identified in the GOME data we found spectral features in the ECMWF fields associated with Kelvin waves with zonal wave numbers 1 or 2 and periods around 15–20 days. These characteristics correspond to the characteristics of the Kelvin waves detected in GOME. The signals are significant throughout the lower stratosphere between ∼100 and 10 hPa and, depending on the period, are largest around 15, 45, or 65 hPa. There is a good correlation between the Kelvin wave signals in the ECMWF zonal wind and temperature and the GOME total ozone column. The induced fluctuations in zonal wind and temperature are, respectively, up to 8 m/s and 2 K. From these induced zonal wind fluctuations, expected total ozone column fluctuations of around 1 DU are calculated, corresponding to the ozone fluctuations found in the GOME data. The results indicate that the analyzed total ozone column fluctuations are mainly caused by transport effects in the lower stratosphere. This study shows that combined use of ECMWF Re‐Analysis data and GOME ozone columns provides a possibility to study the three‐dimensional structure of Kelvin wave activity.