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| Titel |
Radar backscatter sensitivity of soil moisture in vegetation covered areas |
| VerfasserIn |
Faisal Karim, Susan Steele-Dunne, Nick van de Giesen |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250036068
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| Zusammenfassung |
| Radar backscatter is sensitive to the water content of bare soil surface. Vegetation cover
masks the soil surface, reducing the sensitivity of the radar backscatter to soil moisture. The
water-cloud model is used to account for vegetation effects on the copolarized backscatter
coefficient in C and L band.
In this sensitivity study, two different models for opacity are compared to examine their
impact on the sensitivity of total backscatter to soil moisture in the presence of
vegetation. The retrieval algorithms in practice use average value of vegetation factor (b)
to calculate the vegetation optical depth (Ï = bWc) and its transmissivity. This
empirical factor depends only on vegetation type. In the second model for opacity,
dielectric mixing model, vegetation attenuation properties are calculated based on the
dielectric mixing model which accounts for the amounts of free and bound water in the
vegetation.
For all vegetation conditions, vegetation transmissivity decreases linearly with water
content for Ï = bWc model. Using the dielectric mixing model, free water present in
the vegetation is the dominant factor controlling opacity for high vegetation water
conditions and the vegetation transmissivity decreases exponentially with water
content.
The predicted sensitivity of the total backscatter to soil moisture is much higher when
opacity is calculated using the Ï = bWcmodel rather than the dielectric mixing model. |
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