DLR IASI Dust Retrieval

Mineral dust optical depth at 10µm is retrieved over land and ocean from singular vector decomposition based dust information together with dust component extinction spectra from laboratory measurements. With the information of dust component contribution to observed extinction spectra dust optical depth is transferred to 0.5µm. As thermal infrared spectral variability information is used in the retrieval, it is sensitive to dust particles only. The singular vector decomposition based approach allows for dust AOD retrieval also over desert surfaces with highly variable surface emissivity. As only observations of the 8-12µm range are used, the retrieval is independent of solar illumination, thus yielding dust observations twice daily. A pixel-wise retrieval error, which can be used as quality flag, is calculated and brought about with the dust observations. Effective radius estimates are experimental and not validated

Example result (March 02, 2009; descending orbits)


Satellite: Metop (EUMETSAT)
Instrument(s): IASI
Instrument/algorithm PI: Lars Klüser, DLR
Contact details: lars.klueser@dlr.de
Parameter(s): Mineral Dust AOD (0.5µm, 10µm), Effective Radius
Aerosol algorithm: DLR IASI Dust Retrieval
Cloud screening: internal homogeneity and spectra convergence tests
Aerosol model: FTIR measurements of dust component extinction spectra
Retrieval assumptions: neglible contribution of other aerosol types; external mixture of six dust components; singular vectors represent variability of dust,
atmospheric extinction and surface emissivity; non-sphericity of dust particles is implicitly accounted for via dust components
Retrieval limitations: retrieval of AOD10µm and transfer to 0.5µm ; surface temperature may be underestimated from IASI observations; no independent retrieval of effective radius
Spatial, temporal coverage: 2009 (reprocessing ongoing),
60° W-140° E / 0° N-45° N
Spatial, temporal resolution: 0.5° grid, 2200km swath / twice daily
Operations status: experimental
Validation status: evaluation against AERONET coarse mode AOD
Quality control: pixel-wise intrinsic retrieval error, projection approach convergence
last algorithm version: 1.91 (04/2012)
last validation: 08/2011





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The above information was last updated on 19.Juni 2012

Contact: Thomas Holzer-Popp