Regional Water Budgets From Multi-Sensor, Multi-Satellite Remote Sensing
Wood, E; Sheffield, J; Ferguson, C.; Vinukollu, R.
Princeton University

A long standing goal of the WCRP Global Energy and Water Experiment (GEWEX) is observing the global water and energy budgets globally through remote sensing. With the launch of the NASA Earth Observing System (EOS) Aqua platform of sensors, the possibility now exists of retrieving almost all the terms for the terrestrial and atmospheric water and energy budgets. These variables have been retrieved over the Mississippi River Basin, the budgets computed, and compared to terms computed from the Variable Infiltration Capacity (VIC) land surface model. The budget terms, and their sources, are as follows: (i) Precipitation from the TRMM-3B42 product (but other satellite precipitation products like CMORPH can also be used); (ii) terrestrial evapotranspiration, through retrievals that use MODIS surface temperatures, AIRS surface air temperatures and humidity, and CERES (or MODIS) net solar radiation; (iii) change in total storage from GRACE. Soil moisture, which is part of this term is retrieved using AMSR-E and AIRS data. Currently river discharge is from in-situ measurements, but in the future swath altimetry offers a space-based sensor. The surface energy budget terms can be retrieved along with the terrestrial evapotranspiration. The terms of the atmospheric water budget are also determined as follows: (i) change in vapor storage from the time series if AIRS column water vapor estimates; (ii) precipitation and evapotranspiration as discussed above; and (iii) water vapor net divergence through spatial-temporal modeling of the AIRS water vapor, or from reanalysis. The budget terms are compared to values computed from the VIC land surface model and in balances analyzed. The potential exists for assimilating the remote sensing estimates with the land surface estimates to obtain improved overall estimates of the budget terms.


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