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Improving Land-Surface Model Hydrology: Is an Explicit Aquifer Model Better than a Deeper Soil Profile?Land surface models (LSMs) are computer programs, similar to weather and climate prediction models, which simulate the storage and movement of water (including soil moisture, snow, evaporation, and runoff) after it falls to the ground as precipitation. It is not currently possible to measure all of the variables of interest everywhere on Earth with sufficient accuracy. Hence LSMs have been developed to integrate the available information, including satellite observations, using powerful computers, in order to track water storage and redistribution. The maps are used to improve weather forecasts, support water resources and agricultural applications, and study the Earth's water cycle and climate variability. Recently, the models have begun to simulate groundwater storage. In this paper, we compare several possible approaches, and examine the pitfalls associated with trying to estimate aquifer parameters (such as porosity) that are required by the models. We find that explicit representation of groundwater, as opposed to the addition of deeper soil layers, considerably decreases the sensitivity of modeled terrestrial water storage to aquifer parameter choices. We also show that approximate knowledge of parameter values is not sufficient to guarantee realistic model performance: because interaction among parameters is significant, they must be prescribed as a harmonious set.
Document ID
20080030341
Acquisition Source
Goddard Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Gulden, L. E. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Rosero, E. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Yang, Z.-L. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Rodell, Matthew (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Jackson, C. S. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Niu, G.-Y. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Yeh, P. J.-F. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Famiglietti, J. S. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 24, 2013
Publication Date
January 1, 2007
Subject Category
Earth Resources And Remote Sensing
Distribution Limits
Public
Copyright
Public Use Permitted.

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