Impact of ENSO on variability of global CO2 concentration retrievals from GOSAT and AIRS

The correlations between the growth rate of atmospheric CO2 concentrations and the El Nino-Southern Oscillation (ENSO) events are well known. However, investigations of the influence EN-SO events on global CO2 concentrations remain poorly constrained in space. Here, we employ atmospheric CO2 concentrations retrieved from the Greenhouse Gases Observing Satellite (GOSAT) and the Atmospheric Infrared Sounder (AIRS) to investigate the impact of ENSO events on the spatial patterns during July 2009-April 2014. Empirical orthogonal function decomposition was applied to the CO2 concentration series and it showed that the spatial patterns of the GOSAT data compare well with those of the AIRS data. GOSAT and AIRS CO2 concentrations exhibit a significant in-crease during warm ENSO episodes. Furthermore, we directly observed significant variations be-tween the two datasets in the onset and mature phases of ENSO. Specifically, during the onset phase, the GOSAT CO2 concentration decreases more remarkably over high latitudes compared with the AIRS data. During the mature stage, the GOSAT CO2 concentration is reduced over the Atlantic and Pacific oceans, whereas the AIRS CO2 concentration is reduced over North Asia and enhanced over the Pacific Ocean. The differences between the GOSAT and AIRS data for the ENSO decay phase are small. Using the high-resolution spatial and temporal observations available from GOSAT and AIRS data, our study demonstrates that the impact of ENSO on CO2 spatial patterns is significant and requires further investigation.