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| Titel |
What do moisture recycling estimates tell us? Exploring the extreme case of non-evaporating continents |
| VerfasserIn |
H. F. Goessling, C. H. Reick |
| 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 ; 15, no. 10 ; Nr. 15, no. 10 (2011-10-25), S.3217-3235 |
| Datensatznummer |
250012998
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| Publikation (Nr.) |
 copernicus.org/hess-15-3217-2011.pdf |
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| Zusammenfassung |
Moisture recycling estimates are diagnostic measures that could ideally be
used to deduce the response of precipitation to modified land-evaporation.
Recycling estimates are based on moisture-budget considerations in which
water is treated as a passive tracer. But in reality water is a
thermodynamically active component of the atmosphere. Accordingly, recycling
estimates are applicable to deduce the response to a perturbation only if
other mechanisms by which evaporation affects climate do not dominate the
response – a condition that has not received sufficient attention in the
literature. In our analysis of what moisture recycling estimates tell us, we
discuss two such additional mechanisms that result from water's active role.
These are (I) local coupling, by which precipitation is affected locally via
the thermal structure of the atmosphere, and (II) the atmospheric
circulation, by which precipitation is affected on a large spatial scale.
We perform two global climate model experiments: One with and another without
continental evaporation. By this extreme perturbation we test the predictive
utility of a certain type of recycling measure, the "continental recycling
ratio". Moreover, by such a strong perturbation the whole spectrum of
possible responses shows up simultaneously, giving us the opportunity to
discuss all concurrent mechanisms jointly.
The response to this extreme perturbation largely disagrees with the
hypothesis that moisture recycling is the dominant mechanism. Instead, most
of the response can be attributed to changes in the atmospheric circulation,
while the contributions to the response by moisture recycling as well as
local coupling, though noticeable, are smaller. By our case study it is not
possible to give a general answer to the question posed in the title, but it
demonstrates that recycling estimates do not necessarily mirror the
consequences of land-use change for precipitation. |
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