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| Titel |
Dehydration of the stratosphere |
| VerfasserIn |
M. R. Schoeberl, A. E. Dessler |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 11, no. 16 ; Nr. 11, no. 16 (2011-08-18), S.8433-8446 |
| Datensatznummer |
250010013
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| Publikation (Nr.) |
 copernicus.org/acp-11-8433-2011.pdf |
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| Zusammenfassung |
| Domain filling, forward trajectory calculations are used to examine the
global dehydration processes that control stratospheric water vapor. As with
most Lagrangian models of this type, water vapor is instantaneously removed
from the parcel to keep the relative humidity (RH) with respect to ice from
exceeding saturation or a specified super-saturation value. We also test a
simple parameterization of stratospheric convective moistening through ice
lofting and the effect of gravity waves as a mechanism that can augment
dehydration. Comparing diabatic and kinematic trajectories driven by the
MERRA reanalysis, we find that, unlike the results from Liu et al. (2010),
the additional transport due to the vertical velocity "noise" in the
kinematic calculation creates too dry a stratosphere and a too diffuse a
water-vapor tape recorder signal compared observations. We also show that
the kinematically driven parcels are more likely to encounter the coldest
tropopause temperatures than the diabatic trajectories. The diabatic
simulations produce stratospheric water vapor mixing ratios close to that
observed by Aura's Microwave Limb Sounder and are consistent with the MERRA
tropical tropopause temperature biases. Convective moistening, which will
increase stratospheric HDO, also increases stratospheric water vapor while
the addition of parameterized gravity waves does the opposite. We find that
while the Tropical West Pacific is the dominant dehydration location, but
dehydration over Tropical South America is also important. Antarctica makes
a small contribution to the overall stratospheric water vapor budget as well
by releasing very dry air into the Southern Hemisphere stratosphere
following the break up of the winter vortex. |
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