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| Titel |
The retrieval of land surface pressure from MERIS measurements in the oxygen A band |
| VerfasserIn |
R. Lindstrot, R. Preusker, J. Fischer |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250031520
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| Zusammenfassung |
| Measurements of MERIS (Medium Resolution Imaging Spectrometer) on ENVISAT
(Environmental Satellite) are used for the retrieval of surface pressure above land and ice
surfaces. The algorithm is based on the exploitation of gaseous absorption in the oxygen A
band at 762nm. The strength of absorption is directly related to the average photon path
length, which in clear sky cases above bright surfaces is mainly determined by the surface
pressure with minor influences from scattering at aerosols. Sensitivity studies regarding the
influences of aerosol optical thickness and scale height and the temperature profile on the
measured radiances are presented. Additionally, the sensitivity of the retrieval to the accuracy
of the spectral characterization of MERIS is quantified. The algorithm for the retrieval of
surface pressure (SPFUB) is presented and validated against surface pressure maps
constructed from ECMWF sea level pressure data in combination with digital elevation
models. The accuracy of SPFUB was found to be within 10hPa above ice surfaces at
Greenland and 15hPa above desert and mountain scenes in Northern Africa and Southwest
Asia. In a case study above Greenland the accuracy of SPFUB could be enhanced to be
better than 3hPa (Â 0.3%) by spatial averaging over areas of 40 km * 40 km. These
results are of interest for the upcoming CO2/CH4 missions OCO and GOSAT, as an
accurate determination of air mass using measurements in the oxygen A band is
crucial to achieve the accuracy needed to quantify sources and sinks of CO2/CH4. |
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