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| Titel |
A comparison of ASCAT and modelled soil moisture over South Africa, using TOPKAPI in land surface mode |
| VerfasserIn |
S. Sinclair, G. G. S. Pegram |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 14, no. 4 ; Nr. 14, no. 4 (2010-04-06), S.613-626 |
| Datensatznummer |
250012264
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| Publikation (Nr.) |
 copernicus.org/hess-14-613-2010.pdf |
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| Zusammenfassung |
| In this paper we compare two independent soil moisture estimates over
South Africa. The first estimate is a Soil Saturation Index (SSI)
provided by automated real-time computations of the TOPKAPI
hydrological model, adapted to run as a collection of independent
1 km cells with centres on a grid with a spatial resolution of
0.125°, at 3 h intervals. The second set of estimates is the
remotely sensed ASCAT Surface Soil Moisture product, temporally
filtered to yield a Soil Wetness Index (SWI). For the TOPKAPI cells,
the rainfall forcing used is the TRMM 3B42RT product, while the
evapotranspiration forcing is based on a modification of the FAO56
reference crop evapotranspiration (ET0). ET0 is computed using
forecast fields of meteorological variables from the Unified Model
(UM) runs done by the South African Weather Service (SAWS); the UM
forecast fields were used, because reanalysis is not done by SAWS. To
validate these ET0 estimates we compare them with those computed
using observed meteorological data at a network of weather stations;
they were found to be unbiased with acceptable scatter. Using the
rainfall and evapotranspiration forcing data, the percentage
saturation of the TOPKAPI soil store is computed as a Soil Saturation
Index (SSI), for each of 6984 unconnected uncalibrated TOPKAPI cells
at 3 h time-steps. These SSI estimates are then compared with the SWI
estimates obtained from ASCAT. The comparisons indicate a good
correspondence in the dynamic behaviour of SWI and SSI for a
significant proportion of South Africa. |
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