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| Titel |
Recycling of moisture in Europe: contribution of evaporation to variability in very wet and dry years |
| VerfasserIn |
B. Bisselink, A. J. Dolman |
| 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 ; 13, no. 9 ; Nr. 13, no. 9 (2009-09-24), S.1685-1697 |
| Datensatznummer |
250011998
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| Publikation (Nr.) |
 copernicus.org/hess-13-1685-2009.pdf |
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| Zusammenfassung |
Evaporation is a key parameter in the regional atmospheric water cycle.
Precipitation recycling is defined as the contribution of water that
evaporates from a region to precipitation within the same region. We apply a
dynamic precipitation recycling model, which includes a dynamic moisture
storage term, to calculate the warm season variability of the precipitation
recycling over central Europe at a daily time scale for 2003 (dry) and 2006
(wet).
For the central part of Europe advection is the most important contributor
to precipitation. In dry spells in both years 2003 and 2006, when moisture
of advective origin diminishes, local evaporation becomes an important
contributor to precipitation (negative feedback). In two dry periods
(June 2003 and July 2006) where there
is enough moisture storage in the soil to continue evaporation,
precipitation recycling is enhanced. In case
studies we follow the path of an air column for days with high precipitation
recycling to discuss the role of moisture recycling in land-atmosphere
interactions. For 2 days with enough moisture availability (28 May 2003 and
5 July 2006) moisture particles stay long in the study area due to weak
winds. By following the paths we show that the air is transported over land
for a very long distance before it precipitates. It thus takes a
considerable amount of time to traverse the region and capture moisture of
evaporative origin. However, we hypothesize that the precipitation falling
on those days still originates (partly) from oceanic sources, but that the
triggering of precipitation may itself be a result of enhanced instability
induced by soils, which still have sufficient moisture storage.
In dry periods with enough moisture available precipitation recycling acts
as a mechanism to keep the precipitation at a stable level.
In August 2003
evaporation is affecting the precipitation recycling due to the lack of
water availability caused by the dryness of the preceding spring and summer
season. According to a Granger Causality test the evaporation in 2003 exerts
the strongest causal impact on the precipitation recycling ratio. For the
case study of 10 August 2003, the atmosphere is too dry to generate
precipitation with exception of the mountainous regions due to orographical
lifting. |
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