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| Titel |
Should we use a simple or complex model for moisture recycling and atmospheric moisture tracking? |
| VerfasserIn |
R. J. van der Ent, O. A. Tuinenburg, H.-R. Knoche, H. Kunstmann, H. H. G. Savenije |
| 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 ; 17, no. 12 ; Nr. 17, no. 12 (2013-12-06), S.4869-4884 |
| Datensatznummer |
250086019
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| Publikation (Nr.) |
 copernicus.org/hess-17-4869-2013.pdf |
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| Zusammenfassung |
| This paper compares state-of-the-art atmospheric moisture tracking models.
Such models are typically used to study the water component of coupled land
and atmosphere models, in particular quantifying moisture recycling and the
source-sink relations between evaporation and precipitation. There are
several atmospheric moisture tracking methods in use. However, depending on
the level of aggregation, the assumptions made and the level of detail, the
performance of these methods may differ substantially. In this paper, we
compare three methods. The RCM-tag method uses highly accurate 3-D water
tracking (including phase transitions) directly within a regional climate
model (online), while the other two methods (WAM and 3D-T) use a posteriori
(offline) water vapour tracking. The original version of WAM is a
single-layer model, while 3D-T is a multi-layer model, but both make use the
"well-mixed" assumption for evaporation and precipitation. The a posteriori
models are faster and more flexible, but less accurate than online moisture
tracking with RCM-tag. In order to evaluate the accuracy of the a posteriori
models, we tagged evaporated water from Lake Volta in West Africa and traced
it to where it precipitates. It is found that the strong wind shear in West
Africa is the main cause of errors in the a posteriori models. The number of
vertical layers and the initial release height of tagged water in the model
are found to have the most significant influences on the results. With this
knowledge small improvements have been made to the a posteriori models. It
appeared that expanding WAM to a 2-layer model, or a lower release height in
3D-T, led to significantly better results. Finally, we introduced a simple
metric to assess wind shear globally and give recommendations about when to
use which model. The "best" method, however, very much depends on the
research question, the spatial extent under investigation, as well as the
available computational power. |
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