The Climate Data Guide is a National Center for Atmospheric Research (NCAR) project that provides concise and reliable information on the strengths and limitations of the key observational data sets, tools and methods used to evaluate Earth system models and to understand the climate system. The Atmospheric Infrared Sounder (AIRS) project at NASA's Jet Propulsion Laboratory has provided an expert developer guide on the AIRS Obs4MIPs datasets of tropospheric air temperature and specific humidity to the NCAR Climate Data Guide project. Obs4MIPs is an effort to make observational products more accessible for climate model intercomparisons.

The AIRS project has generated decadal-length, global, gridded data sets of temperature and specific humidity for several standard levels in the troposphere for the Obs4MIPS project. This Obs4MIPS version of the AIRS data are available at monthly resolution, 1ºx1º grids and formatted to facilitate easier comparisons with CMIP5 model output. The gridded data are based on the combined retrievals from AIRS, an instrument sensitive to infrared radiation emitted from the surface and atmosphere, and the Advanced Microwave Sounding Unit (AMSU), an instrument sensitive to microwave frequencies that facilitates retrievals even in somewhat cloudy conditions. Both AIRS and AMSU are onboard NASA's AQUA platform. Other AIRS Data including tropospheric temperature, specific humidity, relative humidity, cloud amount, cloud top, and trace gases (CO, O3, and CO2) are also available at either Level 2 swaths or Level 3 1ºx1º grids and several temporal resolutions (daily, 8-day, monthly).

More information can be found on the NCAR Climate Data Guide web page.