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

climate and land surface unaccounted for in the presentgeneration of models. We have analyzed century-scaleobserved annual runoff and precipitation time-series overseveral United States Geological Survey hydrological unitscovering large forested regions of the Eastern United Statesnot affected by irrigation. Both time-series exhibit a positivelong-term trend; however, in contrast to model results, thesehistoric data records show that the rate of precipitationincreases at roughly double the rate of runoff increase. Weconsidered several hydrological processes to close the waterbudget and found that none of these processes acting alonecould account for the total water excess generated by theobserved difference between precipitation and runoff. Weconclude that evaporation has increased over the period ofobservations and show that the increasing trend inprecipitation minus runoff is correlated to observed increasein vegetation density based on the longest available globalsatellite record. The increase in vegetation density hasimportant implications for climate; it slows but does notalleviate the projected warming.Boy, Jean-PaulMonitoring surface and sub-surface mass changesin Africa using high resolution GRACE masconsolutions and altimetryBoy, Jean-Paul 1 ; Carabajal, Claudia C. 2, 3 ; Lutcke, Scott B. 2 ;Rowlands, David D. 2 ; Sabaka, Terence J. 2 ; Lemoine, FrankG. 21. IPGS (UMR 7516 CNRS-UdS), EOST, Strasbourg, France2. Planetary Geodynamics Lab., Code 698, NASA GoddardSpace Flight Center, Greenbelt, MD, USA3. Sigma Space Corporation, Lanham, MD, USASince its launch in March 2002, Gravity Recovery AndClimate Experiment (GRACE) has recovered mass variationsat the Earth’s surface with unprecedented temporal andspatial resolution. We invert directly mass variations fromthe inter-satellite K-band range rate (KBRR) data using alocalized mascon (mass concentrations approach. Usingappropriate constraints, our regional solutions allow bettertemporal (10 days) and spatial (2 degree) resolutions, thanthe classical spherical harmonic solutions. We compare oursolutions to global and regional hydrology models, with aparticular emphasis on the Western Africa monsoon area,where regional models were produced in the context ofALMIP (the AMMA Land-surface Model Inter-comparisonProject). We see that GRACE also captures the currentdrought in Eastern Africa, in agreement with other spacederivedprecipitation and soil-moisture measurements.Thanks to decade of radar altimetry (Topex/Poseidon, Jason-1 & -2 or Envisat), and more recently laser altimetry(ICESat), surface water level variations for major lakes andreservoirs are monitored with a few-centimeter accuracy. Wecompare our GRACE estimates of mass variations of majorlakes and reservoirs in Africa to estimates deduced fromaltimetry measurements. The agreement is larger whencontinental hydrology models, such as GLDAS (Global LandData Assimilation System), which do not include surfacewaters and ground waters, are forward-modeled prior to theinversion of KBRR data. Forward modeling with modelssuch as GLDAS also allows for better retrieval ofgroundwater changes, for example in Northern Africa.Braun, AlexanderOn the Correlation Between Glacier Melting andLake Level Change on the Tibetan Plateau fromAltimetry and GRACEBraun, Alexander 1 ; Duan, Jianbin 2 ; Cogley, Graham 4 ; Lee,Hyongki 3 ; Shum, C. K. 21. Deptartment of Geosciences, The University of Texas atDallas, Richardson, TX, USA2. School of Earth Sciences, The Ohio State University,Columbus, OH, USA3. Civil and Environmental Engineering, University ofHouston, Houston, TX, USA4. Department of Geography, Trent University,Peterborough, ON, CanadaThe Tibetan Plateau (TP) hosts about 37,000 glacierscovering a region of 50,000 km^2. Increasing temperaturesat a rate of 0.3 degrees Celsius per decade in the last 30 yearshave led to significant amounts of melt water with run-offinto several hundred large lakes which on average indicaterising lake levels at a rate of 0.25 m/year (Zhang et al, 2011).The Chinese Glacier Inventory lists 50,000 ice coveredpolygons on the TP, 4000 of those are crossed by ICESatlaser altimetry tracks, and 70 glaciers have more than 100footprints between 2003-2009. We conduct a glacierelevation change analysis from ICESat near-repeat tracksusing up to 19 epochs between March 2003 and October2009. Results in regions covered by in situ mass balanceestimates show excellent agreement with the elevationchange estimates, e.g. ice elevations of the Lhagu glacierchange at a rate of -0.85 m/year compared to fieldobservations for 4 neighboring glaciers at -0.9 m waterequivalent (Yang et al, 2008). We correlate elevation loss withlake level change considering the snow depth change,although the dry climate does not produce significant snowdepth variability. Lake levels are determined using ICESatlaser altimetry, Envisat radar altimetry, and GRACEgravimetry. The estimated contribution of glacier melting tosurface water change will eventually shed light onunderstanding the mass change processes acting on the TPin terms of separating solid Earth, hydrosphere andcryosphere components.Brisco, BrianWetland Coherence for Water Level EstimationBrisco, Brian 1 ; Wdowinski, Shimon 2 ; Murnaghan, Kevin 1 ;Ahern, Frank 3 ; Kaya, Shannon 11. CCRS, Ottawa, ON, Canada2. Univeristy of Miami, Miami, FL, USA3. TerreVista Earth Imaging, Cormac, ON, CanadaINSAR is a mature technology being used operationallyfor a variety of applications including volcano monitoring,42