Abstract

Atmospheric Carbon Monoxide (CO) is an important trace gas in tropospheric chemistry through its impact on the oxidizing capacity, as a precursor of ozone, and as a good tracer of combustion from both anthropogenic sources and wildfires. The Data Assimilation Research Testbed (DART) has been coup... Show moreAtmospheric Carbon Monoxide (CO) is an important trace gas in tropospheric chemistry through its impact on the oxidizing capacity, as a precursor of ozone, and as a good tracer of combustion from both anthropogenic sources and wildfires. The Data Assimilation Research Testbed (DART) has been coupled with the Community Atmospheric Model with Chemistry (CAM-Chem) to perform global ensemble-based chemical data assimilation. The ensemble Kalman filter approach facilitates statistical estimation of error correlations between chemical states (CO and related species) and parameters (including sources). Within this context, we will investigate the role of initial conditions, emission perturbations, transport, and chemistry in the coupled CH4-CO-O3-NOx-OH coupled chemical system. The Measurements of the Pollution In The Troposphere (MOPITT) is the only satellite instrument that can retrieve CO from radiances measurements in both the thermal infrared (TIR) and the near infrared absorption (NIR) bands. Aside from true geophysical variability arising from e.g., different overpass time, instruments have different vertical, horizontal and spectral resolution. Biases can also result from a priori assumptions as well as auxiliary datasets used in the retrieval process. In this work, we compare assimilation experiments of columns and profiles from TIR-only, NIR-only and joint TIR-NIR retrievals from MOPITT. We also assimilate MOPITT (TIR/NIR) jointly with TROPOMI (NIR) and CrIS (TIR). Posterior fields will be evaluated with independent aircraft observations from the NSF Western wildfire Experiment for Cloud chemistry, Aerosol absorption and Nitrogen (WE-CAN) and from the NASA Atmospheric Tomography Mission (ATom). Our set of numerical experiments and the evaluation with aircraft observations allow to evaluate both the current observing system and best assimilation practices (profiles vs. columns). Show less