Assimilation of OCO-2 retrievals with WRF-Chem/DART: A case study for the Midwestern United States

The Data Assimilation Research Testbed (DART) has been extended to be able assimilate the column-average dry-air mole fraction of CO2 (XCO2) retrievals from Orbiting Carbon Observatory 2 (OCO-2) satellite. Atmospheric concentrations over Midwestern United States were estimated by Weather and Forecasting model coupled with Chemistry (WRF-Chem), without assimilating OCO-2 extended-DART. To focus on evaluating effect assimilation, study period was deliberately set January 2016, coldest month in dormant season, minimize influence biogenic flux. Independent ground-based flight observations, as well CarbonTracker 2017 products (CT2017), used evaluate results two distinct approaches. Comparing concentration distribution retrievals, overall root mean square error (RMSE) bias (MBE) between assimilation observations averagely reduced 20.65% 78.49%, difference RMSE MBE respect CT2017 48.29% 28.61%, respectively. Experiments showed that extended-DART could make significantly more consistent products.