|Title||The ENSO signal in atmospheric composition fields: Emission driven versus dynamically induced changes|
|Publication Type||Technical memorandum|
|Secondary Title||ECMWF Technical Memorandum|
|Authors||Inness, A, Benedetti, A, Flemming, J, Parrington, M, Kaiser, J, Remy, S|
The El Niño Southern Oscillation (ENSO) does not only affect meteorological fields but also has a large impact on atmospheric composition. Atmospheric composition fields from the Monitoring Atmospheric Composition and Climate (MACC) reanalysis are used to identify the ENSO signal in tropospheric ozone, carbon monoxide, nitrogen oxide and smoke aerosols, concentrating on the months October to December. During El Niño years all these fields have increased concentrations over Maritime South East Asia in October. The MACC Composition Integrated Forecasting System (C-IFS) model is used to quantify the relative magnitude of dynamically induced and emission driven changes in the atmospheric composition fields. While changes in tropospheric ozone are a combination of dynamically induced and emission driven changes, the changes in carbon monoxide, nitrogen oxide and smoke aerosols are almost entirely emission driven in the MACC model. The ozone changes continue into December, i.e. after the end of the Indonesian fire season while changes in the other fields are confined to the fire season.