Long-term trends and seasonal changes in the CO2 abundance have been monitored since the mid-fifties starting with Charles Keeling. The Atmospheric Infrared Sounder (AIRS), currently orbiting earth on the NASA Aqua mission has been retrieving daily concentrations of CO2 globally directly from observed infrared spectra, without relying on a priori or background information (Chahine et al in GRL, 2005) for the first time. As a greenhouse gas, CO2 blocks the emission of thermal infrared radiation to space thereby contributing to global warming. Daily observations of the distribution of CO2 from space now provide, for the first time, a tool to understand how CO2 is transported from the surface sources and around the globe. To carry out this study we analyze CO2 data retrieved from AIRS spectra and focus on the layer in the atmosphere between 5 and 15 km above the surface. We study the effects of weather patterns on the distribution of CO2 and show that observations of global mid-tropospheric CO2 reveal variability consistent with large-scale transport processes and with major surface sources. In this presentation we mainly concentrate our analysis on the year 2003 where flask measurements from aircraft are available for validation (Matsueda and CMDL)

AIRS was launched into a sun-synchronous polar 705 km altitude orbit on the EOS Aqua spacecraft on May 4, 2002 and covers the 3.7 to 15.4 micron region of the thermal infrared spectrum with spectral resolution of 1200. Since the start of routine data gathering in September 2002 AIRS has demonstrated a stability of 8 milliKelvin per year and spectral accuracy of 10-7 wavenumbers. AIRS returns 3.7 million spectra of the upwelling radiance each day. The operational assimilation of AIRS data at Numerical Weather Prediction centers (by NCEP and ECMWF) has already produced significant positive impact on forecasts in both the northern and southern hemispheres (Chahine et al in BAMS July 2006).