Radiances and Geophysical Quantities from the AIRS instrument

The AIRS mission uses several data processing algorithms to retrieve radiances and geophysical products from the AIRS, AMSU and HSB suite of instruments. These algorithms are, implemented as software in a data processing system. The calibration processing system produces calibrated and geolocated radiances observed along an orbit track (see Figure 2 below), referred to as Level 1B data. These data are used by scientists directly to view small changes in Earth's upwelling radiance features for climate trending and used in geophysical retrievals of atmospheric temperature, water vapor and trace gases. They are also used for spectral and radiometric calibration of broadband instruments and comparison with other hyperspectral instruments.

Retrieved quantities are referred to as Level 2 data, and they are generated by both AIRS-team and CLIMCAPS-Aqua systems. Level 2 data are also available from the JoSFRA retrieval system for limited subsets in space and time. Geophysical quantities reported on regular space-time grids are referred to as Level 3 data. They are available from both the AIRS-team and CLIMCAPS systems.

AIRS Level 1B and Level 2 AIRS-team and CLIMCAPS retrieval quantities are listed in the table below, along with their horizontal resolution. CLIMCAPS has AMSU resolution cloud properties and no phase or effective radius information. A more complete list of retrieved and derived variables for CLIMCAPS is given here in the CLIMCAPS Science Application Guide. JoSFRA products are provided at the AIRS instrument single footprint resolution.

(Please note in the table below, product resolution refers to horizontal resolution, which is approximately 15 km for the AIRS instrument and about 45 km for AMSU.)

Level 1B and Level 2 physical characteristics table