AIRS Global Mid Tropospheric CO2 and CO: Sensitivity to Surface Sources and Transport

W. Wallace McMillan, University of Maryland, Baltimore County, mcmillan@umbc.edu (Presenting)
M T Chahine, Jet Propulsion Laboratory, moustafa.t.chahine@jpl.nasa.gov
Edward T Olsen, JPL, edward.t.olsen@jpl.nasa.gov
Leonid Yurganov, UMBC, yurganov@umbc.edu
Yuk L Yung, Cal Tech, yuk.l.yung@jpl.nasa.gov
Keith Evans, UMBC, evans@umbc.edu
Xun Jiang, JPL, xun.jiang@jpl.nasa.gov
James Randerson, University of California, Irvine, james.randerson@uci.edu
Luke Chen, JPL, luke.chen@jpl.nasa.gov
F W Irion, JPL, bill.irion@jpl.nasa.gov
Thomas Pagano, JPL, thomas.pagano@jpl.nasa.gov

Retrievals of mid-tropospheric abundances of CO2 and CO obtained from the Atmospheric Infrared Sounder (AIRS) in orbit onboard NASA’s Aqua satellite show a substantial spatial and temporal variability that is supported by in situ aircraft measurements. The distribution of the middle tropospheric CO2 is strongly influenced by surface sources and sinks as seen by CO2 vegetation uptake at Park Falls WI and the major stationary CO2 sources in South Africa and Australia. Large-scale circulations such as the mid latitude jet streams and other synoptic weather systems are also visible. AIRS global CO2 retrievals provide the means to analyze sources, sinks and the lifting of CO2 from surface layers into the free troposphere and its transport around the globe. These processes are not accurately represented in current 3-D chemistry transport models.



Although AIRS CO retrievals are most sensitive to the 300 to 700 mb region, large abundances can produce substantial sensitivity in the lowest 2 km. AIRS daily views of 70% of the planet illustrate the large dynamic range of tropospheric CO abundances and dramatic transport events that can encompass a hemisphere. Most such transport events are related to large scale biomass burning or Pyrocumulonimbus outbreaks. However, episodic outflow from some geographic regions appear linked to anthropogenic emissions, e.g. the North Coastal Plain of China and Mexico City. Interannual variations in burning are evident, some with direct links to such global scale climatic phenomena as El Nino. We present examples of these cases as well as an assessment of AIRS CO retrieval accuracy through comparisons with both aircraft in situ and ground-based total column measurements.