AIRS/AMSU/HSB on the aqua mission: design, science objectives, data products, and processing systems

Abstract

The Atmospheric Infrared Sounder (AIRS), the Advanced Microwave Sounding Unit (AMSU), and the Humidity Sounder for Brazil (HSB) form an integrated cross-track scanning temperature and humidity sounding system on the Aqua satellite of the Earth Observing System (EOS). AIRS is an infrared spectrometer/radiometer that covers the 3.7-15.4-m spectral range with 2378 spectral channels. AMSU is a 15-channel microwave radiometer operating between 23 and 89 GHz. HSB is a four-channel microwave radiometer that makes measurements between 150 and 190 GHz. In addition to supporting the National Aeronautics and Space Administration's interest in process study and climate research, AIRS is the first hyperspectral infrared radiometer designed to support the operational requirements for medium-range weather forecasting of the National Ocean and Atmospheric Administration's National Centers for Environmental Prediction (NCEP) and other numerical weather forecasting centers. AIRS, together with the AMSU and HSB microwave radiometers, will achieve global retrieval accuracy of better than 1 K in the lower troposphere under clear and partly cloudy conditions. This paper presents an overview of the science objectives, AIRS/AMSU/HSB data products, retrieval algorithms, and the ground-data processing concepts. The EOS Aqua was launched on May 4, 2002 from Vandenberg AFB, CA, into a 705-km-high, sun-synchronous orbit. Based on the excellent radiometric and spectral performance demonstrated by AIRS during prelaunch testing, which has by now been verified during on-orbit testing, we expect the assimilation of AIRS data into the numerical weather forecast to result in significant forecast range and reliability improvements.

Simulated retrievals for the remote sensing of CO<sub>2</sub>, CH<sub>4</sub>, CO, and H<sub>2</sub>O from geostationary orbit

“…2002 (Aumann et al, 2003;Chahine et al, 2005Chahine et al, , 2008Xiong et al, 2008). The Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) instrument was operational for measurements of atmospheric compositions from 2002 to 2012, with CO 2 , CH 4 , CO, and H 2 O as four of its target species (Buchwitz et al, 2004(Buchwitz et al, , 2007Schrijver et al, 2009;Schneising et al, 2011).…”

“…One exception is SCIAMACHY that had a revisit time of 6 days. The sources and sinks of greenhouse gases are then inferred through flux inversions (e.g., Baker et al, 2010;Nassar et al, 2011). However, the low spatiotemporal measurement densities of the current Earth observing system in LEO result in a lack of information about emissions on smaller spatiotemporal scales (Chevallier et al, 2005;Hungershoefer et al, 2010;Wecht et al, 2014).…”

Satellite observation of atmospheric methane: intercomparison between AIRS and GOSAT TANSO-FTS retrievals

“…Because of a limited number of in situ measurements in time and space domain, the quantification of CH 4 emissions from different sources and in different regions still remains largely uncertain. In recent years, space-borne measurements of CH 4 from satellites have become available, such as the measurements using the thermal infrared (TIR) sensors, which include the Atmospheric InfraRed Sounder (AIRS) on NASA/Aqua (Aumann et al, 2003;Xiong et al, 2008Xiong et al, , 2010a, the Tropospheric Emission Spectrometer (TES) on NASA/Aura (Payne et al, 2009;Wecht et al, 2012;Worden et al, 2012), and the Infrared Atmospheric Sounding Interferometer (IASI) on METOP-A and METOP-B (Xiong et al, 2013;Crevoisiter et al, 2009Crevoisiter et al, , 2013Razavi et al, 2009). Measurements using the Near-Infrared (NIR) sensors include the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) instrument onboard ENVISAT for (Frankenberg et al, 2008, and the Thermal And Near infrared Sensor for carbon Observation (TANSO) onboard the Greenhouse gases Observation SATellite (GOSAT) from 2009 to present (Yokota et al, 2009;Paker et al, 2011;Schepers et al, 2012;Saitoh et al, 2012).…”

“…It has 2378 channels covering 649-1136, 1217-1613 and 2169-2674 cm −1 at high spectral resolution (λ/ λ = 1200, ∼ 0.5 cm −1 ) (Aumann et al, 2003), and the noise equivalent differential temperature (Ne T ) at a reference temperature of 250 K ranges from 0.14 K in the 4.2 µm region (the lower tropospheric sounding) to 0.35 K in the 15 µm region (the upper tropospheric sounding). The spatial resolution of AIRS is 13.5 km at nadir, and in a 24 h period, AIRS nominally observes the complete globe twice per day.…”

“…In order to retrieve CH 4 in both clear and partially cloudy scenes, nine AIRS fields of view (FOVs) within the footprint of the Advanced Microwave Sounding Unit (AMSU) are used to derive a single cloud-cleared radiance spectrum in a field of regard (FOR). The cloud-cleared FOR radiance spectrum is then used to retrieve profiles with a spatial resolution of approximately 45 km (Aumann et al, 2003). The atmospheric temperature profiles, water vapor profiles, surface temperatures and surface emissivity are required as inputs to compute the radiances in the CH 4 absorption band.…”