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| Titel |
Evaluating the impact of SWOT observations§ on the water balance of lakes and wetlands |
| VerfasserIn |
K. Andreadis, D. Möller, E. Rodríguez, D. Alsdorf |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250070627
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| Zusammenfassung |
| Lakes and wetlands can exert controls on the water and energy fluxes, playing an important
role in the local and regional climate. The spatial extent and storage volume of water bodies
globally is poorly known, due to lack of measurements over large areas. The planned Surface
Water Ocean Topography (SWOT) satellite mission will provide observations of water
surface elevation and inundated area globally at an unprecedented spatial resolution. Apart
from being used directly, these observations can be used to constrain the water balance
simulated hydrologic model over large-scale basins. In this study, the Variable Infiltration
Capacity (VIC) macroscale hydrologic model is implemented over the Great Lakes region
within an identical twin synthetic experiment. VIC solves an energy and water balance over a
gridded domain, and represents lakes and wetlands dynamically as fractional areas of each
model grid cell. A baseline simulation of the water and energy balance is designated as
“truth”, and errors in precipitation, temperature and model parameters are added
to simulate a “first-guess” of hydrologic variables of interest. Synthetic SWOT
observations are generated from the instrument simulator (developed at JPL) with the
anticipated orbital and error characteristics. These “virtual” observations are then
assimilated into the “first-guess” model to estimate runoff, evapotranspiration and
sensible/latent heat fluxes. The assimilation technique used is the Ensemble Kalman Filter
(EnKF), which solves the optimal estimation problem by approximating model and
observation errors through a Monte Carlo ensemble approach. The “first-guess”
simulation consists of an ensemble of model states that is propagated temporally
until a SWOT observation becomes available. The impact of merging the SWOT
observations is examined in terms of water and energy fluxes, and the sensitivity of the
results to the different observation errors is assessed. The latter can include errors in
lake/wetland area, storage change, as well as the effects of the SWOT temporal
sampling.
§The SWOT mission has not been formally approved by NASA. The decision to proceed
with the mission will not occur until the completion of the National Environmental Policy
Act (NEPA) process. Material in this paper related to SWOT is for information purposes only. |
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