Infrared retrievals of dust using AIRS: Comparisons of optical depths and heights derived for a North African dust storm to other collocated EOS A‐Train and surface observations

Abstract

[1] AIRS thermal infrared radiance data are used with a fast infrared scattering radiative transfer model to physically retrieve the dust column amount and dust height over both ocean and land. The retrieved optical depths are compared against those retrieved using visible and ultraviolet instruments on the A-Train, while dust layer heights are evaluated against lidar data. The synergistic use of AIRS data is explored by using dust layer heights constrained by CALIPSO retrievals and coarse mode particle sizes over ocean from PARASOL. Optical depths from AIRS correlate well with those from other instruments over ocean (R ≥ 0.9) and are lower over land when compared to MODIS Deep Blue and OMI retrievals (R ≤ 0.8). AIRS-derived dust top heights compare favorably with CALIPSO data and can be used to improve OMI optical depth retrievals over a much larger area than CALIPSO can provide. AIRS data can also provide estimates of dust longwave radiative forcing. For the examples examined here, the forcings are estimated to be about +1.5 and +4.5 W/m 2 per unit visible optical depth over ocean and land, respectively, compared to a shortwave forcing estimate of −50 W/m 2 over ocean. AIRS dust retrievals are possible day or night, can provide dust column amount information over land or ocean, and are unaffected by areas of the oceans covered by sun glint.

New Asia Dust Storm Detection Method Based on the Thermal Infrared Spectral Signature

“…Gang Hong et al [36] put their emphasis on the infrared signature of overlapping cirrus clouds and dust, finding that the spectral signature of the 800-1000 cm −1 region can be used to discriminate coexisting thin cirrus and dust scenes from those associated only with cirrus clouds or dust alone. By using the AIRS thermal infrared observations, Pierangelo et al [37,38], DeSouza-Machado et al [39] and Yao et al [40] individually retrieved the dust altitude and infrared optical depth over different regions, and the results agree favorably with those from Ozone Monitoring Instrument (OMI), MODerate resolution Imaging Spectro-radiometer (MODIS), and Cloud Aerosol LiDAR with Orthogonal Polarization (CALIOP) observations. Gangle et al [41] successfully developed a new volcanic ash detection method using their high spectral information provided by AIRS.…”

“…The Atmospheric Infrared Sounder (AIRS) on board NASA's Aqua satellite platform is a hyperspectral IR temperature and humidity sounder for numerical weather prediction and climate change studies [39]. It has 2378 infrared channels which can measure the earth outgoing radiation in the 3.7-15.4 μm region (3.75-4.58, 6.2-8.2, 8.8-15.4 µm) with a spectral resolution of λ/△λ = 1200 and spatial resolution of 13.5 km (nadir field of view).…”

“…The Cloud Aerosol LiDAR with Orthogonal Polarization (CALIOP) instrument on board the CALIPSO platform, which provides the unique measurements of the global vertical distributions of clouds and aerosols [39,40]. It is a two wavelength LiDAR that transmits and receives backscattered light at laser wavelengths of 532 nm and 1064 nm.…”

Satellite perspective of aerosol intercontinental transport: From qualitative tracking to quantitative characterization

“…These types of observations allow for characterization of aerosol ICT at night or at much finer temporal resolutions during the day (Pierangelo et al, 2004;DeSouza-Machado et al, 2006;Peyridieu et al, 2010;DeSouza-Machado et al, 2010;Knapp et al, 2002;Prados et al, 2007;Thieuleux et al, 2005;. However, geostationary measurements have been underused for studying aerosol ICT.…”

“…Because of the near-zero swath of CALIPSO lidar, however, it is difficult to examine daily variations of aerosol fluxes. In this regard, aerosol layer heights from passive sensors like AIRS (Peyridieu et al, 2010;DeSouza-Machado et al, 2010) and OMI (Dirksen et al, 2009) can help. Because of CALIPSO's relatively low sensitivity to vertically resolved extinction, some aerosol plumes having moderate AOD but large vertical extent may be missed by the lidar.…”