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| Titel |
Comparison of different evaporation estimates over the African continent |
| VerfasserIn |
P. Trambauer, E. Dutra, S. Maskey, M. Werner, F. Pappenberger, L. P. H. Van Beek, S. Uhlenbrook |
| 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 ; 18, no. 1 ; Nr. 18, no. 1 (2014-01-15), S.193-212 |
| Datensatznummer |
250120252
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| Publikation (Nr.) |
 copernicus.org/hess-18-193-2014.pdf |
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| Zusammenfassung |
| Evaporation is a key process in the water cycle with implications ranging,
inter alia, from water management to weather forecast and climate change
assessments. The estimation of continental evaporation fluxes is complex and
typically relies on continental-scale hydrological models or land-surface
models. However, it appears that most global or continental-scale
hydrological models underestimate evaporative fluxes in some regions of
Africa, and as a result overestimate stream flow. Other studies suggest that
land-surface models may overestimate evaporative fluxes. In this study, we
computed actual evaporation for the African continent using a continental
version of the global hydrological model PCR-GLOBWB, which is based on a
water balance approach. Results are compared with other independently
computed evaporation products: the evaporation results from the ECMWF
reanalysis ERA-Interim and ERA-Land (both based on the energy balance
approach), the MOD16 evaporation product, and the GLEAM product. Three other
alternative versions of the PCR-GLOBWB hydrological model were also
considered. This resulted in eight products of actual evaporation, which
were compared in distinct regions of the African continent spanning
different climatic regimes. Annual totals, spatial patterns and seasonality
were studied and compared through visual inspection and statistical methods.
The comparison shows that the representation of irrigation areas has an
insignificant contribution to the actual evaporation at a continental scale
with a 0.5° spatial resolution when averaged over the defined
regions. The choice of meteorological forcing data has a larger effect on
the evaporation results, especially in the case of the precipitation input
as different precipitation input resulted in significantly different
evaporation in some of the studied regions. ERA-Interim evaporation is
generally the highest of the selected products followed by ERA-Land
evaporation. In some regions, the satellite-based products (GLEAM and MOD16)
show a different seasonal behaviour compared to the other products. The
results from this study contribute to a better understanding of the
suitability and the differences between products in each climatic region.
Through an improved understanding of the causes of differences between these
products and their uncertainty, this study provides information to improve
the quality of evaporation products for the African continent and,
consequently, leads to improved water resources assessments at regional
scale. |
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