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| Titel |
Technical Note: A comparison of model and empirical measures of catchment-scale effective energy and mass transfer |
| VerfasserIn |
C. Rasmussen, E. L. Gallo |
| 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. 9 ; Nr. 17, no. 9 (2013-09-05), S.3389-3395 |
| Datensatznummer |
250085922
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| Publikation (Nr.) |
 copernicus.org/hess-17-3389-2013.pdf |
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| Zusammenfassung |
| Recent work suggests that a coupled effective energy and mass transfer (EEMT) term,
which includes the energy associated with effective precipitation and primary
production, may serve as a robust prediction parameter of critical zone
structure and function. However, the models used to estimate EEMT have been
solely based on long-term climatological data with little validation using
direct empirical measures of energy, water, and carbon balances. Here we
compare catchment-scale EEMT estimates generated using two distinct approaches:
(1) EEMT modeled using the established methodology based on estimates of monthly
effective precipitation and net primary production derived from
climatological data, and (2) empirical catchment-scale EEMT estimated using data
from 86 catchments of the Model Parameter Estimation Experiment (MOPEX) and
MOD17A3 annual net primary production (NPP) product derived from Moderate
Resolution Imaging Spectroradiometer (MODIS). Results indicated positive and
significant linear correspondence (R2 = 0.75; P < 0.001)
between model and empirical measures with an average root mean square error
(RMSE) of 4.86 MJ m−2 yr−1. Modeled EEMT values were consistently
greater than empirical measures of EEMT. Empirical catchment estimates of the
energy associated with effective precipitation (EPPT) were calculated
using a mass balance approach that accounts for water losses to quick
surface runoff not accounted for in the climatologically modeled
EPPT. Similarly, local controls on primary production such as solar
radiation and nutrient limitation were not explicitly included in the
climatologically based estimates of energy associated with primary
production (EBIO), whereas these were captured in the remotely sensed
MODIS NPP data. These differences likely explain the greater estimate of
modeled EEMT relative to the empirical measures. There was significant positive
correlation between catchment aridity and the fraction of EEMT partitioned into
EBIO (FBIO), with an increase in FBIO as a fraction of the total
as aridity increases and percentage of catchment woody plant cover decreases.
In summary, the data indicated strong correspondence between model and
empirical measures of EEMT with limited bias that agree well with other
empirical measures of catchment energy and water partitioning and plant
cover. |
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