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

obtained from the Fifth Microwave Water and EnergyBalance (MicroWEX-5) experiment which was conductedduring the growing season of sweet-corn from Day of Year(DoY) 68 (March 9) to DoY 150 (May 30) in 2006. In situ soilmoisture observations were obtained every fifteen minutesat depths of 2, 4, 8, 16, 32, 64, and 120 cm and L-bandbrightness temperature observations at H-polarization and50° incidence angle were measured every fifteen minutes.Comparisons of RZSM estimates using both synthetic andfield observations during the MicroWEX-5 experiment wereconducted to understand the improvement in RZSMestimation using both in situ and remotely sensedmeasurements. The performances of the algorithm werecompared by assimilating both H and V polarizations ofmicrowave observations for passive, and VV and HHpolarizations for active observations. When assimilatingsynthetic observations, the mean estimates of VSM05cmand RZSM improved up to 80%, 50%, and 90%, as comparedto the open-loop estimates, when passive, active, and APobservations were assimilated, respectively. However, themeans decreased to 10%, when assimilating fieldobservations of TB,h from the Fifth Microwave Water EnergyBalance Experiment (MicroWEX-5), suggesting other sourcesof uncertainty that those from model parameters andforcings.Monsiváis-Huertero, AlejandroSOIL MOISTURE FIELD MEASUREMENTS:THEVALIDATION PROCESS USING MICROWAVEREMOTE SENSINGRamos Hernandez, Judith G. 1 ; Monsiváis-Huertero,Alejandro 2 ; Marrufo, Liliana 11. Hidraulica, Instituto de Ingenieria, Distrito Federal,Mexico2. Aeronautica, Instituto Politecnico Nacional, DistritoFederal, MexicoThe estimation of soil moisture (ms) is a key variable inthe large-scale fluxes of energy and water interchange in thesoil-vegetation-atmosphere transfer system (SVAT). mspresents a space and temporal variation, that is crucial whencatchment analysis are required. This variable is influencedby the same hydrological cycle processes, the vegetation andthe edaphologyical and topography aspects and also vary intime and space. Although there are several methods todetermine ms, the majority of them are looking to one ortwo of these aspects. In situ ms observations could beobtained applying direct and indirect methods such asgravimetric, lysimeters, tensiometers and reflectrometry (i.eTime or Frequency Domain Reflectometry). However, in thelast decades, the remote sensing techniques (RS) allows theidentification of several surface characteristics. In particular,the active (radar) microwave sensors that are sensitive to thedielectric properties of a surface as well as the ms. Thus, it ispossible to find a relationship between the totalbackscattering coefficient from the radar image (°total)and the soil moisture at the surface (msfm). One of thecommonly used formulations to estimate these scatteringmechanisms is the Radiative Transfer Theory (RTT), whichproposes an iterative method to solve the scattered energyequations at upward and downward directions (i.e. MichiganMicrowave Canopy Scattering Model). In this paper, ms wasestimated using radar remote sensing (ENVISAT imagery)and the MMICS method and the validation was achieved byapplying the FDR method on a tropical climate. The studyarea is the Zapotes riparian wetland. The measure sitesdesign was subject to the accessibility in the field. Eight siteswere defined and tested in two campaigns, seven of them areshowed in Table 1. The implementation of radar imagery(2010) using the MIMISC models provides a relationship(Table 2) that for all cases have a correlation coefficient (R2)higher than 0.99 with an error of 0-5% in comparison to insitumsfm observations.Table 1. Soil moisture (ms) measureds at 10 cm depthTable 2. Empirical models for each site of the Zapotes wetlandMoradi, AyoubMulti-sensor study of hydrological changes inCaspian SeaMoradi, Ayoub 1, 2 ; Viron, Olivier D. 1, 2 ; Metivier, Laurent 21. Earth Sciences, University of Paris Diderot, Paris, France2. Spatial Geophysics and planetary, Paris Institut ofPhysics of Globe, Paris, FranceThe main purpose of this study is to determine howgeodetic and remote sensing data can be combined togetherin order to better monitor the hydrological processes in aclosed large water bodies like Caspian Sea. The usedobservation techniques are principally different, with theirown benefits and disadvantages. Combining heterogeneousinformation aims at improving our knowledge on the realityof hydrological processes, also to determine, and possiblycorrect, the shortages of different methods. We used timeseries of 3 kinds of dataset, Altimetry, Gravimetry andRemote Sensing data (table below). We reached the trends ofchange of water level and change of total water mass usingaltimetry and gravimetry data respectively. Using MODIStime series we detected changes of snow, grass andvegetation cover in the Caspian basin entirely and changes ofwater extent of the lake (the image is an example forclassification). Altimetry and gravimetry results show anannual change about 35 centimetres and an interannualchange about 70 centimetres in water height from year 1992to present. Interannual changes of water would be verified bychanges in snow cover over the basin. After removing leakageaffect on the gravimetry results the comparison shows a fairconsistency between the altimetry and gravimetry results.105