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Contributions of different water storage compartments to total storage change from multi-sensor analysis. Introduction. CLIVAR-Hydro. Signals of Climate Variability in Continental Hydrology from Multi-Sensor Space and In-situ Observations and Hydrological Modeling. Object. Mean. Target.
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Contributions of different water storage compartments to total storage change from multi-sensor analysis
Introduction Sarah Abelen / CLIVAR-Hydro
CLIVAR-Hydro • Signals of Climate Variability in Continental Hydrology from Multi-Sensor Space and In-situ Observations and Hydrological Modeling Object Mean Target Researchers Multi-Sensor Space Observations Signals of Climate Variability + 3 PhD Students Continental Hydrology In-situ Observations Hydrological Modeling Sarah Abelen / CLIVAR-Hydro
Gravimetry Surface Water Ground Water Soil Moisture Snow Water and Ice Concept Schönheinz D., BTU-Cottbus Sarah Abelen / CLIVAR-Hydro
Soil Moisture Sarah Abelen / CLIVAR-Hydro
Theory • Basic Principle: Fresnel reflection equation Reflectivity of the ground (r) for a certain polarization (H or V) depends on: • the viewing angle of the sensor (Ѳ) • the dielectric constant (k) depends on the constituents of the ground (air, soil, water) Example: dry soil: k = 5 water: k = 80 Jackson 2005 Jackson 2002 Sarah Abelen / CLIVAR-Hydro
Passive vs. Active Sensors • AMSR-E = Advanced Microwave Scanning Radiometer for EOS • Time span: 2002 – present • Pixel size: 25 km x 25 km(of data products) • Largest wavelength: 4.3 cm = 6.9 GHz (C-Band) Njoku et al. 2003 Sarah Abelen / CLIVAR-Hydro
AMSR-E Data Sarah Abelen / CLIVAR-Hydro
Monthly Soil Moisture Sarah Abelen / CLIVAR-Hydro
Selection of the Test-Site Sarah Abelen / CLIVAR-Hydro
Limitations • Gravimetric changes (GRACE) can be identified in regions with: • High soil moisture (≥ 20 kg/m2) Example: 20 kg/m2 = 0.2 g/cm2 and 10 cm depth • Strong variation in soil moisture • Large spatial extend (> 300 km x 300 km) • Soil moisture (AMSR-E) can be acquired in regions with: • Low vegetation water content (< 1.5 kg/m2) Sarah Abelen / CLIVAR-Hydro
Variation of Soil Moisture Paraná River large changes in river basins no changes in the deserts Sarah Abelen / CLIVAR-Hydro
Variation of Soil Moisture with Quality Mask mainly the deserts remain with small variations only few areas with larger variations remain Sarah Abelen / CLIVAR-Hydro
Mean of Soil Moisture with Quality Mask variation is high but the mean value is low Sarah Abelen / CLIVAR-Hydro
Summary and Outlook Sarah Abelen / CLIVAR-Hydro
Summary and Outlook • Gravimetry total change in water storage • Remote Sensing + In-situ compartments (e.g. soil moisture) • Principle for Soil Moisture: Reflection dielectric constant water content • Soil moisture products exist for active and passive sensors • Problems AMSR-E: • vegetation water content (< 1.5 kg/m2) mostly related to low variability / magnitude of soil moisture • Problems GRACE: • mass changes are small for soil moisture • lack of knowledge on depth of soil moisture (≤ 1 cm for C-Band) Sarah Abelen / CLIVAR-Hydro
References Jackson, T., 2002. Remote sensingofsoilmoisture: implicationsforgroundwaterrecharge. Hydrogeology Journal, 10(1), 40-51. Jackson, T., 2005. SoilMoisture. In Encyclopediaofsoils in theenvironment. Elsevier, pp. 392-398. Njoku, E. et al., 2003. Soilmoistureretrievalfrom AMSR-E. Geoscienceand Remote Sensing, IEEE Transactions on, 41(2), 215-229. Njoku, E. 2004, updateddaily. AMSR-E/Aqua L3 SurfaceSoilMoisture, Interpretive Parameters, & QC EASE-GridsV002, 01.07.2002 - 31.07.2010. Boulder, Colorado USA: National Snow andIce Data Center. Digital media. Sarah Abelen / CLIVAR-Hydro
AMSR-E • AMSR-E = Advanced Microwave Scanning Radiometer for EOS (AMSR-E) • Space Agency: NASA • Satellite: Aqua (precipitation, evaporation, water cycle) • Data products: • Time span: 2002 – present • Spatial resolution: 25 km2 (of data products) • Largest Wavelength: 4.3 cm = 6.9 GHz (C-Band) • Soil Moisture • Vegetation Water • content • Land-cover (10 types) http://en.wikipedia.org/wiki/File:Aqua_satellite_simulation.jpg Sarah Abelen / CLIVAR-Hydro
Variation of Valid Soil Moisture • No pronounced temporal variation • Vegetation Water Content is mostly below 1.5 kg/m2 Sarah Abelen / CLIVAR-Hydro
Integration of Other Data Sources 2000 Sarah Abelen / CLIVAR-Hydro
Test-Site Proposal 35° Lat 35°- 65° Long Sarah Abelen / CLIVAR-Hydro
Annual Cycle Sarah Abelen / CLIVAR-Hydro
Ancillary Data: Quality Control Flags Sarah Abelen / CLIVAR-Hydro
Selection of one Grid Cell Sarah Abelen / CLIVAR-Hydro
Soil Moisture: Time Variation Errorbar of 0.06 g/cm3 Validity for Vegetation Water Content < 1.5 kg/m2 • Soil Moisture goes up to 0.2 g/cm2 • Errorbar is relatively high • Limitation is the Vegetation Water Content Njoku et al. 2003 Sarah Abelen / CLIVAR-Hydro
Object Mean Researchers Target Signals of Climate Variability 2 Continental Hydrology 1 Signals of Climate Variability 3 Multi-Sensor Space Observations + 3 PhD Students 4 In-situ Observations 5 Hydrological Modeling Sarah Abelen / CLIVAR-Hydro