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

carbon balance. Soil moisture measurements are also ofimportance in modeling and predicting extreme events suchas floods and droughts. The algorithms and data productsfor SMAP are being developed in the SMAP Science DataSystem (SDS) Testbed. In the Testbed algorithms aredeveloped and evaluated using simulated SMAPobservations as well as observational data from currentairborne and spaceborne L-band sensors including datafrom the SMOS and Aquarius missions. We report here onthe development status of the SMAP data products. TheTestbed simulations are designed to capture various sourcesof errors in the products including environment effects,instrument effects (non-ideal aspects of the measurementsystem), and retrieval algorithm errors. The SMAP projecthas developed a Calibration and Validation (Cal/Val) Planthat is designed to support algorithm development (prelaunch)and data product validation (post-launch). A keycomponent of the Cal/Val Plan is the identification,characterization, and instrumentation of sites that can beused to calibrate and validate the sensor data (Level 1) andderived geophysical products (Level 2 and higher).Nolin, Anne W.Vegetation and Snow: Remote Sensing andInteractions from the Local to the ContinentalScaleNolin, Anne W. 1 ; Coons, Lexi 1 ; Blauvelt, Katie 1 ; Gleason,Kelly 1 ; Sproles, Eric 11. College of Earth, Ocean, and Atmospheric Sciences,Oregon State University, Corvallis, OR, USAIn cold land environments, snow cover is a key part ofthe terrestrial water cycle and snow-vegetation interactionsare intricately linked and bidirectional. For example, reducedsnow cover increases soil moisture stress affecting vegetationgrowth patterns and multiplying impacts to vegetationincluding carbon storage, phenology, pest life history, andfire frequency. Land cover affects aerodynamic roughnessand turbulent fluxes at the snow-atmosphere-vegetationinterface. Changes in land cover due to natural and humanimpacts (wildfire, pest infestation, forest harvest) affectpatterns of snow accumulation and ablation. Moreover, thepresence of forest canopy and shrub vegetation significantlyinhibits our ability to measure and monitor our changingsnowpacks. In this presentation, we present new concepts inmeasuring and understanding snow-vegetation interactionswith relevance to remote sensing. First, we debut a new acanopy adjustment for fractional snow covered area that usesvegetation density and height. Because forest canopyobscures the snow below whereas shrubs typically do not,canopy height must be known if one is to provide accuratemaps of snow-covered area. Second, positive correlationsbetween snow cover and vegetation have been observed.Using 10 years of MODIS data we demonstrate relationshipsbetween green biomass and antecedent snow cover frequencyfor various regions in the United States. Last, we identifyhow changing land cover due to wildfire or forest harvestaffect snow energy balance and how such changes can bemeasured from space using sensor technologiesrecommended by the Decadal Survey.http://www.geo.oregonstate.edu/~nolina/RESEARCH_GROUP/Noone, David C.Evaluation of tropical continental water cyclingfrom space-based observations of water isotoperatiosNoone, David C. 1 ; Berkelhammer, Max 1 ; Worden, John 2 ;Schmidt, Gavin 31. Univ Colorado, Dept Atmospheric & Oceanic Sci,Boulder, CO, USA2. Jet Propulsion Laboratory, California Institute ofTechnology, Pasadena, CA, USA3. Goddard Institute for Space Siences, New York, NY, USAThe continental water cycle in the tropics is a leadingcomponent of the global latent heat budget. Uncertainty inthe rates of exchange of water between the tropical landsurface and the atmosphere persist as uncertainties inestimates of the global energy budget. Uncertainties arisebecause of lack of constraint on the pathways that watertakes as it moves from the atmosphere to the landscape andback. Model estimates of land-atmosphere exchange rely onestimates of model parameters that are not well constrainedby observations. Inter-model differences are associated withinherently small scale processes such as infiltration,interception of water on canopies and rooting depth. At theregional scale, the aggregate of complex ecosystem fluxes canbe better understood with knowledge of the isotopiccomposition of water because the isotopic compositionprovides constraint on the net fluxes that result from theconservation and partitioning of isotope ratios duringexchange. Estimates of the D/H isotope ratio of water vaporfrom the Tropospheric Emission Spectrometer (TES) onNASA’s Aura spacecraft are used to deduce features of theterrestrial water budget. The isotopic information is usefulin two ways: 1) it provides a tracer of mechanismscontrolling vertical transport from the boundary layer,through clouds and to the troposphere, and 2) it proves ageophysical “tag” which reflects the fraction of water vaporwhich is derived from transpiration versus water vapor withan oceanic origin and associated with low level advection.Isotopic ratios from TES are used to estimate seasonal andinterannual variations in the terms contributing to theatmospheric water budget of the Amazon and near theIndian/Asian monsoons. Results are contrasted withestimates of continental recycling and seasonal changes inmoisture budgets derived from non-isotopic means. Thework highlights the advantages of using isotopicinformation in integrated assessments of continental waterbudgets. The study also highlights the advantage of pairingisotopic measurements with other trace gases such as CO2and CO to constrain vertical transport, and points to theneed for better surface and aircraft based observations of theisotopic composition to complement the regional synthesisoffered by satellite remote sensing.112