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

potentially good predictors of LAI and SVF, while a foliarmoisture index was the best predictor of forest cover in thisarea. The combined use of LiDAR and Landsat showed goodpotential to generate accurate, fully-distributed vegetationmetrics required by hydrologic models, and the specificmethodologies we developed demonstrated applicability to awide range of forest stand types of different age, height,density and health status.Velicogna, IsabellaIncrease in groundwater storage in discontinuouspermafrost areas in Eurasia and impact onvegetation productivityVelicogna, Isabella 1, 2 ; Tong, Jinjun 1 ; Kimball, John 4 ; Zhang,Tingjun 31. Dept of Earth System Science, Univ of California Irvine,Irvine, CA, USA2. JPL, Pasadena, CA, USA3. University of Colorado, Boulder, CO, USA4. University of Montana, Polson, MT, USAWe use monthly measurements of time-variable gravityfrom the GRACE (Gravity Recovery and ClimateExperiment) satellite mission to determine the increase interrestrial water storage (TWS) in Eurasia, during the period2002-2011. We compare monthly TWS from GRACE withTWS from time series of precipitation (P) minus evapotranspiration(ET) from ERA-Interim re-analysis andobservational river discharge (R) in the Lena, Yenisei and Obriver basins. We find an excellent agreement between the twotime series of TWS. If we account for a negative bias in theaverage annual precipitation during the analyzed period, weeffectively close the terrestrial water budget. From thiscomparison, we attribute both the increase in R and in TWSto an increase in P. In the Lena river basin the TWS increaseis dominated by a large signal in an area of discontinuouspermafrost. We attribute the observed signal to an increasein groundwater storage of 68+/-19 cubic km or to surfacewater recharging the ground water through areas notunderlain by permafrost, while changes in active layerthickness have likely less impact. These TWS changes willhave a significant impact on the terrestrial hydrology of theregion, including increased baseflow and alteration ofseasonal runoff. We also analyze the temporal and spatialcorrelation between TWS and Normalized DifferenceVegetation Index (NDVI) and Net Primary Production (NPP)from MODIS. We show how the correlation changes withinwater rich and water limited areas as well as in function ofdifferent land cover types. We find that vegetationproductivity in the Lena river basin is mainly controlled bytemperature constraints rather than moisture availability,while in the Ob river basin it is mainly controlled by waterlimitation.146Verosub, Kenneth L.Determining River Flows Using Historical AerialPhotography and Satellite ImageryVerosub, Kenneth L. 1 ; Molnia, Bruce 21. Dept Geology, Univ California Davis, Davis, CA, USA2. United States Geological Survey, Reston, VA, USAHistorical aerial photography and satellite imagery arean important data archive that can be used to study changesin the terrestrial water cycle. We have developed a methodthat uses the width of a river as measured in older imageryas a key component in determining the flow in the river atthe time the imagery was collected. The approach requiresknowledge of the topography of the site at which the flow isbeing determined, but such information can be collected inthe present, using ground surveys and/or modern imagery.Once the topographic information is available, we usenumerical integration to determine the hydraulic parametersof the channel. These parameters are then used to calculatethe flow as a function of width. The method has beenvalidated using gauged rivers in the United States for whichboth older imagery and historical flow data are available.Uncertainties in the determination of any given flow are onthe order of 20% or better. The approach provides a way ofobtaining new flow data for sites that have been inaccessibledue to either physical or geopolitical considerations. It canalso be used to extend the record of sites where monitoringhas been discontinued or done only recently. Our approachmakes it possible to study trends in river flows due to globalclimate change over a greater geographic extent and/or alonger time scale than is currently possible. It can alsoprovide better estimates of the impacts of changes in landuse and water resources management on river flows.Vila, Daniel A.Validation of the Hydrological Monthly Productsusing Passive Microwave SensorsVila, Daniel A. 1, 2 ; Hernandez, Cecilia 2 ; Ferraro, Ralph R. 3, 2 ;Semunegus, Hilawe 41. DSA/CPTEC/INPE, Cachoeira Paulista, Brazil2. CICS, ESSIC/UMD, College Park, MD, USA3. NESDIS, NOAA, Camps Spring, MD, USA4. NCDC, NOAA, Ashville, NC, USAGlobal monthly rainfall estimates and otherhydrological products have been produced from 1987 to2009 using measurements from the Defense MeteorologicalSatellite Program (DMSP) series of Special SensorMicrowave Imager (SSM/I), while from 2009 to present, theSpecial Sensor Microwave Imager/Sounder (SSMI/S) is beingused for retrieving several hydrological parameters fromprecipitation and total precipitable water to snow and icecover. The aim of this paper has two purposes: discuss themethodology used to merge both sensors and the impact onthe time series analysis and a second objective is related withthe validation of the current data with in-situ data, like theGlobal Precipitation Climatology Centre (GPCC)monitoring product among others.