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| Titel |
Toward all weather, long record, and real-time land surface temperature
retrievals from microwave satellite observations |
| VerfasserIn |
Carlos Jimenez, Catherine Prigent, Filipe Aires, Sofia Ermida |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250144758
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| Publikation (Nr.) |
 EGU/EGU2017-8622.pdf |
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| Zusammenfassung |
| The land surface temperature can be estimated from satellite passive microwave observations,
with limited contamination from the clouds as compared to the infrared satellite
retrievals. With ∼60% cloud cover in average over the globe, there is a need for “all
weather,” long record, and real-time estimates of land surface temperature (Ts) from
microwaves. A simple yet accurate methodology is developed to derive the land surface
temperature from microwave conical scanner observations, with the help of pre-calculated
land surface microwave emissivities. The method is applied to the Special Sensor
Microwave/Imagers (SSM/I) and the Earth observation satellite (EOS) Advanced Microwave
Scanning Radiometer (AMSR-E) observations?, regardless of the cloud cover. The
SSM/I results are compared to infrared estimates from International Satellite Cloud
Climatology Project (ISCCP) and from Advanced Along Track Scanning Radiometer
(AATSR), under clear-sky conditions. Limited biases are observed (∼0.5 K for
both comparisons) with a root-mean-square difference (RMSD) of ∼5 K, to be
compared to the RMSE of ∼3.5 K between ISCCP et AATSR. AMSR-E results are
compared with the Moderate Resolution Imaging Spectroradiometer (MODIS) clear-sky
estimates. As both instruments are on board the same satellite, this reduces the
uncertainty associated to the observations match-up, resulting in a lower RMSD of ∼
4K. The microwave Ts is compared to in situ Ts time series from a collection of
ground stations over a large range of environments. For 22 stations available in the
2003-2004 period, SSM/I Ts agrees very well for stations in vegetated environments
(down to RMSD of ∼2.5 K for several stations), but the retrieval methodology
encounters difficulties under cold conditions due to the large variability of snow and
ice surface emissivities. For 10 stations in the year 2010, AMSR-E presents an
all-station mean RMSD of ∼4.0 K with respect tom the ground Ts. Over the same
stations, MODIS agrees better (RMSD of 2.4 K), ?but AMSR-E provides a larger
number of Ts estimates by being able to measure under cloudy conditions, with an
approximated ratio of 3 to 1 over the analysed stations. At many stations the RMSD of
the AMSR-E clear and cloudy-sky are comparable, highlighting the ability of the
microwave inversions to provide Ts under most atmospheric and surface conditions. |
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