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| Titel |
Improving estimated soil moisture fields through assimilation of AMSR-E soil moisture retrievals with an ensemble Kalman filter and a mass conservation constraint |
| VerfasserIn |
B. Li, D. Toll, X. Zhan, B. Cosgrove |
| 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 ; 16, no. 1 ; Nr. 16, no. 1 (2012-01-12), S.105-119 |
| Datensatznummer |
250013115
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| Publikation (Nr.) |
 copernicus.org/hess-16-105-2012.pdf |
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| Zusammenfassung |
| Model simulated soil moisture fields are often biased due to errors in input
parameters and deficiencies in model physics. Satellite derived
soil moisture estimates, if retrieved appropriately, represent the spatial
mean of near surface soil moisture in a footprint area, and can be used to
reduce bias of model estimates (at locations near the surface) through data
assimilation techniques. While assimilating the retrievals can reduce bias,
it can also destroy the mass balance enforced by the model governing
equation because water is removed from or added to the soil by the
assimilation algorithm. In addition, studies have shown that assimilation of
surface observations can adversely impact soil moisture estimates in the
lower soil layers due to imperfect model physics, even though the bias near
the surface is decreased. In this study, an ensemble Kalman filter (EnKF)
with a mass conservation updating scheme was developed to assimilate
Advanced Microwave Scanning Radiometer (AMSR-E) soil moisture retrievals, as
they are without any scaling or pre-processing, to improve the estimated
soil moisture fields by the Noah land surface model. Assimilation results
using the conventional and the mass conservation updating scheme in the
Little Washita watershed of Oklahoma showed that, while both updating
schemes reduced the bias in the shallow root zone, the mass conservation
scheme provided better estimates in the deeper profile. The mass
conservation scheme also yielded physically consistent estimates of fluxes
and maintained the water budget. Impacts of model physics on the
assimilation results are discussed. |
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