Evaluation of Variability in GOME-2 Total Water Vapor and Nitrogen Dioxide Columns Associated with Natural Oscillations

Abstract

This study presents the variability of total water (H2O) vapor and nitrogen dioxide (NO2) columns associated with natural oscillations [quasi-biennial oscillation (QBO), El Niño–Southern Oscillation (ENSO), North Atlantic Oscillation (NAO)], based on monthly Global Ozone Monitoring Experiment (GOME)-2 level-3 trace gas column data produced under the Atmospheric Composition Satellite Application Facility (AC SAF) project. The periods studied are January 2007–December 2018 for GOME-2A, January 2013–May 2025 for GOME-2B, and January 2019–May 2025 for GOME-2C. The QBO-type periodicity in total NO2 is strongest in the tropics with a measurable amplitude of a few percent. Going from low- to midlatitudes, there is a phase shift in the QBO impact seen in total NO2. Variability of total H2O is not significantly correlated with the QBO. The effects of ENSO on total H2O are clearly seen in the tropics, while the effect of NAO is evident in the northern midlatitudes. Variability in total H2O from GOME-2 in regions affected by ENSO and NAO is compared with that from Copernicus Atmosphere Monitoring Service (CAMS) reanalysis and the European Centre for Medium-Range Weather Forecasts (ECMWF)-Hamburg (ECHAM)/Modular Earth Submodel System (MESSy) Atmospheric Chemistry (EMAC) model results, and good agreement is found between the datasets. Overall, our results show that the total column NO2 and H2O data from GOME-2 capture well the variability associated with large-scale natural fluctuations in the recent past, supporting that QBO/ENSO/NAO–tracer correlations can serve as a diagnostic tool for model and reanalysis evaluations. This provides confidence that data from the newer versions of the GOME-2 instrument (GOME-2B, GOME-2C) can be quite useful for monitoring the response of NO2 and H2O to potential anomalies in the QBO/ENSO/NAO signals in the near future and can significantly help in evaluating the representation of these natural cycles in climate model simulations of trace gases in the coming years.