Post on 19-Dec-2015
Potential Soil Moisture Retrieval from Aquarius Instrument
Mississippi State University
Geosystems Research Institute
2NASA RPC Review (3/2/09)
Aquarius Evaluation Team & Collaborators
• MSU Team– Robert Moorhead– Xingang Fan– Valentine Anantharaj– Georgy Mostovoy– Graduate student (MSU GRI and ECE Dept.)
• External Team– GMU & CREW
• Partner Agencies– Garry Schaeffer (USDA NRCS)– Steve Hunter (United States Bureau of Reclamation)
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Identified Decision Support Needs
• Routine analysis land surface state over the continental needs
watersoilssunweatherclimatevegetationterrain
watersoilssunweatherclimatevegetationterrain
observe, model, assimilateobserve, model, assimilate
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Anticipated Societal Benefits
1. provides critical information to support drought monitoring and mitigation
2. provides essential information for predicting droughts based on weather and climate predictions
3. supports irrigation water management4. supports fire risk assessment5. supports water supply forecasting and NWS flood forecasting6. supplies a critical missing component to assist with snow, climate
and associated hydrometeorological data analysis7. supports climate change assessment8. enables water quality monitoring9. supports a wide variety of natural resource management & research
activities such as NASA remote sensing activities of soil moisture and ARS watershed studies.
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Purpose of RPC Aquarius Experiments
• Evaluate feasibility and usefulness of Aquarius data for decision support in water resources management and other cross-cutting applications.
Approach:I. Aquarius Evaluation: Test, characterize, and evaluate
potential Aquarius soil moisture data via an OSSE.
II. Downscaling for land surface modeling: Downscale Aquarius data and evaluate by land surface modeling.
III. Sensitivity Studies: Different LSM(s), input parameters
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Experimental Objectives and Approach
• Using an OSSE, retrieve potential space-based soil moisture estimation using Aquarius radiometer and scatterometer.
• Generate moisture and energy fluxes at 10x10 km2 using a land surface model to assimilate the retrieved synthetic (simulated) soil moisture product.
• Evaluate experimental products for use in water management applications.
• Quantify uncertainties.
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Identified Tasks
• Develop and finalize experimental design. (Otherwise mistake could be expensive to correct). This will particularly include strategies for nature run, emission and backscatter models, orbital and sensor model, selection of retrieval algorithms.
• Develop and validate nature run.• Retrieve soil moisture using the methodology outlined
later.• Compare with the benchmark data aggregated from the
NR. Quantify errors and uncertainties.• Document and publish results
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Aquarius OSSE Design
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Generalized OSSE Framework(Courtesy: JCSDA)
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HYDROS OSSE Example
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Aquarius OSSE: Experimental Design
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Remote Sensing ConceptRadiative Transfer at the surface
Soil Surface
Vegetation Surface
Ts
Tb
Tsτc
T1
T3
T2
Tbp can be written as
Tbp = T1+T2+T3
T1,T2,T3 correspond to contributions in the above equation
Ts = Soil temperature
Tc = Vegetation temperature
τc = function of vegetation
water content
esp and rsp are functions of
soil water content
)exp(1)exp(11)exp( cspcpccspsbp rTeTT
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1/8 deg domain size: 144x80 points 30.1875 – 40.0625 N, 107.8125 – 89.9375 WIf aggregated to 100km: 18x10points
1/8 deg Nature Run using LIS-CLM
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Orbital Senor ModelingNature Run
Forward ModelingSoil Moisture Retrieval
Nature RunLIS modelCLM LSM
NLDAS Forcing1/8 deg
TOA (Satellite)Emission model
Radiometer/ Backscatter
1/8 deg
Satellite ObsOrbital modelRe-samplingAdding Noise
1 deg
RetrievalInversion modelRetrieved soil
moisture1 deg
Data assimilationLIS model
NOAH LSMCDAS + ENKF
1/8 deg
ValidationCompare to
“truth”
OSSE Flowchart (simplified)
Nature RunLIS CLM
NLDAS Forcing1/8 deg
TOA (Satellite)Emission model
Radiometer/ Backscatter
1/8 deg
RetrievalInversion modelRetrieved soil
moisture1 deg
Data assimilationLIS model
NOAH LSM + ENKF1/8 deg
ValidationCompare to
“truth”
Nature Run Output of Soil moisture at 10 soil layers, hourly output from 2002-09-01 to 2003-10-311/8 deg resolution
Soil moisture of the top layer at 13 UTC 2002-09-01
Nature Run using LIS-CLM
Nature RunLIS modelCLM LSM
1/8 deg
TOA (Satellite)Emission model
Radiometer/ Backscatter
1/8 deg
RetrievalInversion modelRetrieved soil
moisture1 deg
Data assimilationLIS model
NOAH LSM + ENKF1/8 deg
ValidationCompare to
“truth”
Forward Emission Output of Brightness Temperature (Tb)as can be seen from radiometer, and radar echo (Sigma) as from back scatterometer, a total of 15 maps each time point:Three look angles (29,38,45)Five variables: two Tb (h,v) and three simga (hh,hv,vv)
Tb(h) Tb(v)
sigma(hh) sigma(hv) sigma(vv)
Shown below are Tb(h), Tb(v), sigma(hh), sigma(hv), sigma(vv) from look angle 29 at 13 UTC 2002-09-01
Forward ModelingMicrowave Emissions and Backscatter
Orbital Sensor ModelingSimulation of Aquarius Footprints
Experiment Domain30.1875 – 40.0625 N, 107.8125 – 89.9375 W
Simulation of Aquarius Footprints
Radiometer ScatterometerParameter Inner
BeamMiddle Beam
Outer Beam
Inner Beam
Middle Beam
Outer Beam
Look Angle 25.8 33.8 40.3 25.9 33.9 40.3
Azimuth Angle 9.8 -15.3 6.5 9.7 -15.3 6.5
Footprint Size (km) 89 x 80 113 x 88 150 x 106 68 x 60 85 x 67 113 x 80
• Satellite Tool Kit (STK 8.0) has been used for simulation of Aquarius Footprints
• Generated geodetic Latitude – Longitude contour line reports for re-sampling with the temperature data
Radiometer Footprint
Scatterometer Footprint
Nature RunLIS modelCLM LSM
1/8 deg
TOA (Satellite)Emission model
Radiometer/ Backscatter
1/8 deg
Orbital modelSatellite ObsRe-samplingAdding Noise
1 deg
RetrievalInversion modelRetrieved soil
moisture1 deg
Data assimilationLIS model
NOAH LSM + ENKF1/8 deg
ValidationCompare to
“truth”
• Satellite Tool Kit (STK 8.0) has been used for simulation of Aquarius Footprints
• Generated geodetic Latitude – Longitude contour line reports for re-sampling with the temperature data
Radiometer Footprint
Scatterometer Footprint
FootprintsInner Beam : 94X76 kmMiddle Beam: 120X84 kmOuter Beam: 156X97 km
Nature RunLIS modelCLM LSM
1/8 deg
TOA (Satellite)Emission model
Radiometer/ Backscatter
1/8 deg
Orbital modelSatellite ObsRe-samplingAdding Noise
1 deg
RetrievalInversion modelRetrieved soil
moisture1 deg
Data assimilationLIS model
NOAH LSM + ENKF1/8 deg
ValidationCompare to
“truth”
Look angle 29 Look angle 38 Look angle 45
7-day Tb(h)
7-daySigma(hh)
Look angle 29 Look angle 38 Look angle 45
Noise
Gaussian noise of zero-mean and stdev equals 1K and 0.5 dB for Tb and sigma, respectively
Forward emission model output of Tb and sigma are re-sampled for the Aquarius footprints, and then aggregated to 1-degree resolution. The satellite has a 7-day revisit time period, so the following shows only one Tb and one sigma over a 7-day period, from three look angles.
Nature RunLIS modelCLM LSM
1/8 deg
TOA (Satellite)Emission model
Radiometer/ Backscatter
1/8 deg
Orbital modelSatellite ObsRe-samplingAdding Noise
1 deg
RetrievalInversion modelRetrieved soil
moisture1 deg
Data assimilationLIS model
NOAH LSM + ENKF1/8 deg
ValidationCompare to
“truth”
Average of Tb(h) and Tb(v) retrievals
Average of sigma(hh), sigma(hv), and sigma(vv)
retrievals
Look angle
29
38
45
Retrieved soil moisture[from brightness temperature (Tb) & backscatter (sigma)]
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Data Assimilation Experiments(Preliminary Results)
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Soil moisture at a lightly-vegetated pixel(34.3125°N, 108.562°W )
TruthOpen Loop (No D/A)
With Data Assimilation
Retrieved SM
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Soil moisture at a heavily-vegetated pixel(34.3125°N, 94.5625°W )
TruthOpen Loop (No D/A)
With Data Assimilation
Retrieved SM
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Soil Moisture(domain averaged)
TruthOpen Loop (No D/A)
With Data Assimilation
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Summary of Progress
• Completed Tasks– OSSE experimental design– Nature Run (synthetic truth)– Orbital Sensor Modeling and Simulations– Microwave Emissions and Backscatter Modeling– Soil moisture retrieval– Synthesis of experimental SM product– Assimilation of SM product using LIS EnKF (preliminary)
• Final Steps (in progress)– Validation of DA runs– Error analysis– Final evaluation (document and publish)
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Contact Information
Valentine Anantharaj<vga1@msstate.edu>
Tel: (662)325-5135