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| Titel |
The aggregate description of semi-arid vegetation with precipitation-generated soil moisture heterogeneity |
| VerfasserIn |
C. B. White, P. R. Houser, A. M. Arain, Z.-L. Yang, K. Syed, W. J. Shuttleworth |
| 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 ; 1, no. 1 ; Nr. 1, no. 1, S.205-212 |
| Datensatznummer |
250000094
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| Publikation (Nr.) |
 copernicus.org/hess-1-205-1997.pdf |
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| Zusammenfassung |
| Meteorological measurements in the Walnut Gulch catchment
in Arizona were used to synthesize a distributed, hourly-average time series
of data across a 26.9 by 12.5 km area with a grid resolution of 480 m for
a continuous 18-month period which included two seasons of monsoonal rainfall.
Coupled surface-atmosphere model runs established the acceptability (for
modelling purposes) of assuming uniformity in all meteorological variables
other than rainfall. Rainfall was interpolated onto the grid from an array
of 82 recording rain gauges. These meteorological data were used as forcing
variables for an equivalent array of stand-alone Biosphere-Atmosphere Transfer
Scheme (BATS) models to describe the evolution of soil moisture and surface
energy fluxes in response to the prevalent, heterogeneous pattern of convective
precipitation. The calculated area-average behaviour was compared with
that given by a single aggregate BATS simulation forced with area-average
meteorological data. Heterogeneous rainfall gives rise to significant but
partly compensating differences in the transpiration and the intercepted
rainfall components of total evaporation during rain storms. However, the
calculated area-average surface energy fluxes given by the two simulations
in rain-free conditions with strong heterogeneity in soil moisture were
always close to identical, a result which is independent of whether default
or site-specific vegetation and soil parameters were used. Because the
spatial variability in soil moisture throughout the catchment has the same
order of magnitude as the amount of rain falling in a typical convective
storm (commonly 10% of the vegetation's root zone saturation) in a semi-arid
environment, non-linearity in the relationship between transpiration and
the soil moisture available to the vegetation has limited influence on
area-average surface fluxes. |
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