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

Norouzi, HamidrezaLand Surface Characterization Using Multi-satelliteMicrowave ObservationsNorouzi, Hamidreza 1 ; Aghakouchak, Amir 2 ; Azarderakhsh,Marzieh 31. The City University of New York - NYCCT, New York, NY,USA2. University of California - Irvine, Irvine, CA, USA3. The City College of New York, New York, NY, USAMicrowave observations at low frequencies exhibitsensitivity to surface and subsurface properties as expressedby surface emissivity. Moreover, the microwave brightnesstemperatures at different frequencies originate fromdifferent depths which can provide structural profile of thesurface. This information can be used to characterize thevegetation structure or soil moisture profiles. In this study,we developed a global land emissivity product using AMSR-Epassive microwave data after removing the effect of theatmosphere. Also, the impact of the difference in penetrationdepths between passive microwave and thermal temperatureson the retrieval of land emissivity was investigated. There is adifference in phase time and amplitude between physicaltemperature from IR and MW brightness temperature,especially in arid and semi-arid regions where microwavepenetrates deeper than thermal Infrared observations. Thediurnal variation of passive microwave brightnesstemperature using similar frequencies of different satelliteswas analyzed. Principal Component Analysis (PCA) is usedto explore the spatial variation of passive microwave diurnalcycle. The effect of the moisture in vegetation and soil on theshape of the diurnal cycle at different frequencies wereexamined. Larger diurnal amplitude is observed in aridregions while densely vegetated areas present loweramplitude. The differences in emissivities at differentfrequencies are consistent with vegetation structures.Different land classes and their changes through the time isalso investigated.Nosetto, MarceloLand-use changes in temperate Argentina:Assessing their hydrological impacts with remotesensingNosetto, Marcelo 1, 2 ; Jobbágy, Esteban 1, 21. IMASL - CONICET & UNSL, Grupo de EstudiosAmbientales, San Luis, Argentina2. Ciencias Agropecuarias, FICES, Villa Mercedes, ArgentinaVegetation exerts a strong control on water balance andkey hydrological variables like evapotranspiration, wateryield or even the flooded area may result severely affected byvegetation changes. Particularly, transitions between treeandherbaceous-dominated covers, which are taking place atincreasing rates in southern South America, may have thegreatest impact on the water balance. Both the clearing ofnative dry forests for grain production and the afforestationof grasslands with fast-growing tree species are occurring indifferent areas of temperate Argentina. The fast replacementof perennial pastures by soybean in the Pampas may alsolead to noticeable hydrological effects. Based on Landsat andTerra imagery analysis, field sampling and hydrologicalmodeling we evaluated vapor and liquid ecosystem waterfluxes, soil moisture changes and groundwater levelsdynamics in temperate Argentina and provided a usefulframework to assess potential hydrological impacts of landusechanges. Different native (dry forests, grasslands) andmodified vegetation types (eucalyptus plantations, singlesoybean crop and wheat/soybean rotation, alfalfa pastures)were considered in the analysis. Despite contrastingstructural differences, native dry forests and eucalyptusplantations displayed evapotranspiration values remarkablysimilar (1100 mm y1) and significantly higher thanherbaceous vegetation covers (780, 670 and 800 mm y1for grasslands, soybean and wheat/soybean system,respectively). In agreement with evapotranspirationestimates, soil profiles to a depth of 3 m were significantlydrier in woody covers (0.31 m3 m3) compared to nativegrasslands (0.39 m3 m3), soybean (0.38 m3 m3) andwheat/soybean rotation (0.35 m3 m3). Where groundwaterwas shallow (< 5 m of depth), soil profiles at eucalyptusplantations showed higher salts accumulation compared tocrops and grasslands. Groundwater and soil salinizationincreased as the water balance became more negative and thegroundwater shallower. Liquid water fluxes (deep drainage +surface runoff) were at least doubled in herbaceous covers, assuggested by modeling (170 mm y1) and 357 mm y1),for woody and herbaceous covers, respectively). Our analysisrevealed the hydrological outcomes of different vegetationchanges trajectories and provided valuable tools that willhelp to anticipate likely impacts, minimize uncertainties andprovide a solid base for sustainable land use planning.Nunes, AnaChallenges in Assessing South AmericanHydroclimate: How Can Satellite-BasedPrecipitation Products Help?Nunes, Ana 11. Federal University of Rio de Janeiro, Rio de Janeiro, BrazilAssessing climate variability and change at regionalscales can be challenging due to nonlinear interactionsamong different scale phenomena, particularly in regionswith sparse long-term observational records such as SouthAmerica. Therefore, reconstructing regional climate throughdynamically consistent models can be useful over remoteareas of South America, and also provide additional variablesets for energy and water-cycle studies over the entirecontinental domain. By considering a global reanalysis as theboundary condition provider, and constraining a regionalclimate model’s solution to closely follow the boundaryfields at scales above 1,000 km, one would expect that largescalefeatures from global reanalysis could be preservedduring long-term regional simulations. However,parameterized processes such as convection can cause theregional model’s full solution (base field + perturbation) to113