AIRS mid-tropospheric co2 for assimilation by meteorological models

The Atmospheric Infrared Sounder (AIRS) enables us to monitor for the first time the global distribution and transport of middle tropospheric CO2 over oceans, land and the poles. Mid tropospheric CO2 retrieved by the Atmospheric Infrared Sounder shows a substantial spatiotemporal variability that is supported by in situ aircraft measurements [Chahine et al., 2008; Olsen et al., 2009]. The distribution of middle tropospheric CO2 is strongly influenced by surface sources and large scale circulations such as the mid latitude jet streams and by synoptic weather systems, most notably in the summer hemisphere. In addition, the effects of stratosphere troposphere exchange are observed during a final stratospheric warming event.

The retrieved AIRS mid-tropospheric CO2 are compared to in situ measurements by commercial and research aircraft and to retrievals by land based upward looking Fourier Transform Interferometers. Validation of AIRS CO2 data with respect to in situ observations has demonstrated an accuracy of 1-2 ppm and an average annual trend increase of ~2 ppm/year, between 2003 and 2008. We will focus on the significance of the retrieved CO2 results by establishing their quantitative bounds on the random and systematic errors. This is of paramount importance in modeling and to provide the means to understand the sources and sinks and the lifting of CO2 from surface layers into the free troposphere and its subsequent transport around the globe.