Carbon monoxide (CO) is a useful tracer of atmospheric pollution, with direct emissions from incomplete combustion such as biomass and fossil fuel burning as well as secondary production from the oxidation of methane (CH4) and volatile organic compounds (VOCs). Atmospheric CO distributions have a seasonal cycle that is mainly driven by photochemical destruction, which allows CO to build up over winter and early spring in higher latitudes. The lifetime of CO of weeks to months is long enough to allow observations of pollution plumes and their subsequent long-range transport, but short enough to distinguish the plumes against background seasonal distributions. As a dominant sink for the hydroxyl radical (OH), CO plays a critical role in atmospheric reactivity and is considered a short-lived climate pollutant (SLCP) because of its impacts on methane lifetime as well as carbon dioxide and ozone formation. Thus long term global data on CO distribution and variability is key to monitoring air quality and the impact of fires. Satellite based instruments can provide these data but the associated errors and uncertainties are also needed. In a recent peer reviewed study, a team including AER Principal Scientist Karen Cady-Pereira and Staff Scientist Jen Hegarty evaluated the new single-pixel TROPESS (Tropospheric Ozone and its Precursors from Earth System Sounding) profile retrievals of carbon monoxide (CO) from the Cross-track Infrared Sounder (CrIS) using vertical profiles of in situ observations from the National Oceanic and Atmospheric Administration (NOAA) Global Monitoring Laboratory (GML) aircraft program and from the Atmospheric Tomography Mission (ATom) campaigns. The TROPESS optimal estimation retrievals are produced using the MUSES (MUlti-SpEctra, MUlti-SpEcies, MUlti-Sensors) algorithm, which has heritage from retrieval algorithms developed for the EOS/Aura Tropospheric Emission Spectrometer (TES). Note that MUSES uses the OSS radiative transfer model developed at AER. The comparison results provided confidence in the use of TROPESS/CrIS CO profiles and error characterization for continuing the multi-decadal record of satellite CO observations.
Figure Caption: SNPP observations of the Pole Creek fire in Utah, USA, on 13 September 2018. The Great Salt Lake is in the upper left of each panel, and state borders with Idaho, Wyoming, and Colorado are indicated by solid straight lines. Dotted lines indicate a 1° latitude by 1° longitude grid, with the top left corner at 42◦ N, −113◦ E. Panel (a) shows CLIMCAPS/CrIS CO at 500 hPa (MMR converted to VMR). Panel (b) shows the TROPESS/CrIS tropospheric CO column average VMR, and panel (c) shows the corresponding NASA Worldview SNPP/VIIRS image with clouds and smoke (true color) as well as fire thermal anomalies (red).
Citation: TROPESS/CrIS carbon monoxide profile validation with NOAA GML and ATom in situ aircraft observations
M. Worden, G. L. Francis, S. S. Kulawik, K. W. Bowman, K. Cady-Pereira, D. Fu, J. D. Hegarty, V. Kantchev, M. Luo, V. H. Payne, J. R. Worden, R. Commane, K. McKain
Atmos. Meas. Tech.,15, 5383–5398, 202