Atmospheric Infrared Sounder (AIRS)
The Atmospheric Infrared Sounder (AIRS) is an instrument aboard NASA's Aqua satellite. Each card on this page represents a product derived using data from the AIRS instrument. Products on blue cards, marked as "Research," are still in development, or exist mainly for academic purposes. For more details on any product, click the link at the bottom of each eard. To see actual real-time data, click the link at the bottom right of the card.
For more information, see the AIRS Overview at the bottom of this page.
RESEARCH
AIRS Profile
54-level Version 5.2 L2 retrieved temperature and dewpoint profiles from AIRS.
RESEARCH
Effective Cloud Fraction
The product of physical cloud fraction and cloud emissivity to measure opacity using CO2 slicing.
RESEARCH
Carbon Dioxide
13.3 µm CO2 absorption channel depicting tropospheric temperature.
RESEARCH
Shortwave IR
3.9 µm channel depicting both reflected and emitted atmospheric and surface emission.
RESEARCH
Cloud Top Pressure
Atmospheric pressure level corresponding to the height of cloud tops using CO2 slicing.
RESEARCH
% Cloud Free Channels
Percentage of AIRS channels uncontaminated by clouds as determined by CO2 sorting.
AIRS Overview
Day Aqua Orbit
Night Aqua Orbit
Aboard the EOS polar-orbiting Aqua satellite with an early afternoon (1:30 PM) equator crossing time, the Atmospheric Infrared Sounder (AIRS) coupled with the Advanced Microwave Sounding Unit (AMSU) form a sounding system capable of providing a highly detailed view of the atmosphere. AIRS is a cross-track scanning infrared spectrometer/radiometer with 2378 spectral channels between 3.7 and 15.4 µm (650 and 2675 cm-1). This high spectral resolution lends itself to retrieving a variety of atmospheric variables ranging from temperature, moisture, and ozone to carbon dioxide, trace gases, and dust and is used for advances in both weather and climate studies. The numerous applications, as well as its heritage for future hyperspectral instruments, have been used to both adapt classic and create new techniques.
Two key products from AIRS are the temperature and moisture vertical profiles. These profiles have an approximate accuracy of 1K for 1-km layers for temperature and 15% RH in 2-km layers for water vapor with the lowest errors occurring in the mid-troposphere for clear-sky cases over water (Tobin et al. 2006; Divakarla et al. 2006). Because AIRS is coupled with the Advanced Microwave Sounding Unit (AMSU), it can retrieve profiles in both clear and partly cloudy scenes. However, the profiles that are obtained in partly cloudy scenes are of lower quality than those obtained in clear scenes, and quality indicators provided with the AIRS data allow users to determine which pressure levels contain the highest quality information. A key component of the Version 5.0 EOS Science Team AIRS profile data is level-by-level error characteristics for temperature and moisture (Susskind, personal communication). These error characteristics allow the selection of a specific pressure level within the retrieval above which quality data is contained. Prudent use of the quality indicators allows data above clouds to be used rather than completely disregarding entire profiles that may contain low, broken clouds. The figure below shows the lowest pressure level of quality data (given by the quality indicators) for a set of AIRS overpasses and a corresponding infrared image from GOES pinpointing the location of clouds. This figure shows that thick clouds result in no AIRS retrieval or only the very top levels of an AIRS retrieval, but low or mid-level clouds still allow for some mid- and upper-level sounding information to be retained.
Infrared image of cloud locations from GOES-11 (left) and maximum pressure level of quality data as determined by EOS Science
Team Version 5.0 quality indicators (right) for 07-08 UTC 8 September 2006.
Specifically, SPoRT uses the raw radiances to produce imagery and products derived from this imagery (including cloud top pressures, effective cloud fractions, and percent cloud-free channels). These products are applied to regional radiance data assimilation activities. In addition to its work with AIRS radiances, SPoRT uses the Level-2 retrieved soundings to supply the Huntsville National Weather Service Weather Forecast Office with temperature and moisture profiles for use in their AWIPS system. AIRS profiles are also used in profile assimilation activities.
