2012 AGU Chapman Conference on Remote Sensing of the ...

global scale, having a better spatial coverage and increasednumber of observations. The developed merging strategy isbased on the use of AMSR-E night-time and ASCATobservations, of which the qualities were determined usingthe Triple Collocation verification technique. To improve thespatial coverage and the number of observations, AMSR-Eday-time and WindSat observations could be included in themerging procedure. Here, we present a quality assessment ofsoil moisture anomalies from active and passive microwaveobservations which could be used for extending the recentlydeveloped merging strategy. We base our analysis on the useof two different evaluation techniques, the TripleCollocation and the Rvalue verification technique, and weinclude modeling to support the use of soil moistureretrievals from day-time passive microwave observations. Theresults from this study may be used for more comprehensivemerging strategy as they suggest that surface soil moistureestimates from day-time passive microwave observationsincrease in quality with increasing vegetation cover. Inregions where passive and active products perform similarlywell, weighting functions may be derived using the resultspresented in this study.Parinussa, RobertA Multi-decadal soil moisture dataset from passiveand active microwave soil moisture retrievalsParinussa, Robert 1 ; De Jeu, Richard 1 ; Dorigo, Wouter 2 ; Liu,Yi 3, 1 ; Wagner, Wolfgang 2 ; Fernandez, Diego 41. Hydrology and Geo-environmental sciences, VUUniversity Amsterdam, Amsterdam, Netherlands2. Institute for Photogrammetry and Remote Sensing,Vienna University of Technology, Vienna, Austria3. Climate Change Research Centre, University of NewSouth Wales, Sydney, NSW, Australia4. ESA, ESRIN, Frascati, ItalyRecently, as part of the Water Cycle MultimissionObservation Strategy (WACMOS) project a methodology hasbeen developed to build a harmonized multi-decadal satellitesoil moisture dataset. The VU University Amsterdam –National Aeronautics and Space Administration (VUA-NASA) passive microwave products derived from foursatellites and the Vienna University of Technology (TU-Wien) active microwave products derived from two satelliteswere used in this study. The products were merged, rescaled,ranked and blended into one final product. The harmonizedsoil moisture values were compared to in situ data from theInternational Soil Moisture Network (ISMN) and generallyshowed a better agreement than the individual products.Interannual variability and long term trends within this soilmoisture dataset were analyzed and evaluated usingadditional datasets, including tree ring data and oceanoscillation indices. These results gave us confidence in thequality of this new product. This product will now befurther improved and implemented within the ClimateChange Initiative (CCI) programme of ESA.Paris, AdrienIMPROVING DISCHARGE ESTIMATES IN ALARGE, POORLY GAUGE BASIN BY TUNING AHYDROLOGICAL MODEL WITH SATELLITEALTIMETRY INFORMATIONCalmant, Stephane 1 ; Paris, Adrien 2, 1 ; Santos da Silva,Joecila 3 ; Collischonn, Walter 2 ; Paiva, Rodrigo 2, 4 ; Bonnet,Marie-Paule 4 ; Seyler, Frederique 51. OMP-LEGOS-IRD, Toulouse Cedex 09, France2. IPH - UFRGS, Porto Alegre, Brazil3. CESTU - UEA, Manaus, Brazil4. UMR-GET-IRD, Toulouse, France5. UMR-Espace DEV-IRD, Montpellier, FranceAccurate modeling of discharge in a basin requires alarge amount of information. This information is threefold:First, knowledge of the river geometry such as the slope ofriver surface and bottom, the width of the cross sectionthroughout the river course, the height at whichoverbanking occurs; second knowledge of the watershed,DTM soil characteristics and vegetation type; and last,physical parameters such as a friction coefficient, includingits space and time variations (i.e. seasonal variations withwater level). In most large tropical basins, knowledge of theriver geometry is dramatically lacking, in particular in themost upstream, remote, parts. Satellite altimetry providestime series of altitude of the river surface. Because theseseries are naturally leveled, slope of the river surface can alsobe derived easily. Also, in some favorable cases, the geometryof the section crossed by the satellite track is imaged by thesuccessive height profiles, between the lowest and higheststages. The time sampling of these series is quite poor,ranging from every decade in the best cases to a fewmeasurements a year in the worse cases. In turn, the spacingis rather good, from a few km to a few hundreds of km. TheMGB model was developed at IPH to compute river flow inlarge basins. Originally, for reaches where actual data arelacking, the riverbed geometry was derived from empiricalgeomorphological relationships. Besides, the flow dynamicshad to be left unconstrained and unchecked down until thefirst gauging station. In the present study, we present recentimprovements obtained in the flow modeling by tuning theMGB model in order that the river geometry and modeloutputs better fit altimetry series. We present and discussthe benefits gained in the case of the Japura-Caqueta river, inthe Amazon basin. The Japura-Caqueta river is atransboundary river, called Caqueta in its upstreamColombian part and Japura in its downstream, Brazilianpart. No gauge measurements are available in the Colombianpart, and only 3 gauging stations exist in the Brazilian part,when 29 ENVISAT tracks cross the river, making as muchopportunities to put constrains on model parameters suchas reach width, river slope, or model outputs such as stagevariations.116