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| Titel |
Quantifying spatio–temporal variations of soil moisture control on surface energy balance and near-surface air temperature |
| VerfasserIn |
Clemens Schwingshackl, Martin Hirschi, Sonia Isabelle Seneviratne |
| 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 |
250140356
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| Publikation (Nr.) |
 EGU/EGU2017-3730.pdf |
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| Zusammenfassung |
| Soil moisture plays a crucial role for the energy partitioning at the Earth’s surface. Changing
shares of latent and sensible heat fluxes, caused by soil moisture variations, can affect both
near-surface air temperature and precipitation. Here, we use a simple framework for the
dependence of evaporative fraction (the ratio of latent heat flux over net radiation) on soil
moisture to analyze spatial and temporal variations of land–atmosphere coupling and its
effect on near-surface air temperature. Using three different data sources (two re-analysis
datasets and one observation-based data combination), three key parameters for the relation
between soil moisture and evaporative fraction are estimated: 1) the frequency of occurrence
of different soil moisture regimes, 2) the sensitivity of evaporative fraction to soil
moisture in the transitional soil moisture regime, and 3) the critical soil moisture
value which separates soil moisture- and energy-limited evapotranspiration regimes.
Large parts of the global land area enter the transitional regime during at least some
months of the year. Based on the identification of transitional regimes, the effect of
changes in soil moisture on near-surface air temperature can be analyzed. Typical
soil moisture variations can impact air temperature by several kelvin. The results
emphasize the role of soil moisture for atmosphere and climate and constitute a useful
benchmark for the evaluation of the respective relationships in Earth System Models. |
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