The Landsat Data Continuity Mission(LDCM): Landsat 8
Transcript of The Landsat Data Continuity Mission(LDCM): Landsat 8
The Landsat Data Continuity Mission(LDCM):Landsat 8
Not your fathers Landsat
John R Schott, Aaron Gerace and Nima PahlevanSponsor: United States Geological Survey (USGS) and NASA/Goddard
January 2012
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LDCM carries two pushbroom instruments:The 9 band Orbital Land Imager (OLI) and
The 2 band Thermal Infrared Sensor (TIRS) ETM+ OLI
• Same swath width, same resolution as L 7• global coverage, merged OLI-TIRS product
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Size Matters
Landsat 7&8 (30m)
16 day repeat
Free web access
Terra‐MODIS (500m)
Daily coverage
Free web access
Rochester Embayment (Lake Ontario)
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LDCM Features: New bands
LDCM Response
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0.2
0.4
0.6
0.8
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350 850 1350 1850 2350Wavelength
Resp
onse
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LDCM Features: 12 bit Quantizationvs. 8 bit on L7
OLI (12-bit)
Landsat 7 (8-bit)
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46 vs. 68 units of chlorophyll
OLI’s pushbroom design leads to
significantly better SNR
SNR for ~ 3% refelector
CA
BlueGreen
Red
NIR
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100150200250300350
0 1 2 3 4 5 6
Band numbers
Mea
n/St
d OLI
L7
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Water IOPs-Absorb-Scatter
Modeling the Constituent Retrieval Process: Hydrolight
Wind Speed
Sensor locationSolar location
CHL SM CDOM
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Spectralsampling
Quantize
AVIRIS
ETM+
OLI
Add Noise
Modeling the Constituent Retrieval Process: At the Sensor
Sensorresponse
Hydrolightoutput
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Modeling the Constituent Retrieval Process:
M
CD
OM
CHL
Top of Atmosphere
Air/Water Interface
CHL=3SM=4
CDOM=7
CHL(g/L)
SM(mg/L)
CDOM
0 0 0.5 .5 .51 1 .753 2 15 4 27 8 4
12 10 724 14 1046 20 1268 24 14
Modtran
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Interpolation Process
min [(ST - SP)2 ]
λ
Sp predicted
SQ Error[CHL] [SM] [CDOM]
TRUE
FALSE
[ SM ][CDOM ]
LUT
[CH
L]
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AVIRIS
ETM+
OLI
Modeling the Constituent Retrieval Process: Summary
– Average residuals can be expressed as a percent of the total range of constituents. CHL [0 – 68], SM [0 – 24], CDOM [0 – 14]
– 10% error is our target for this experiment.
Spectralsampling QuantizeAdd Noise
Sensorresponse
HydrolightOutputX 2000
Constituentretrieval
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Results: Perfect atmospheric compensation
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SNR Margins
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Results: Perfect atmospheric compensation
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Atmospheric Compensation IssuesHydrolight-generated water pixels as seen
through a 40km visibility atmosphere.
• (Left) TOA Radiance, (Right) Resampled to six LDCM bands.• Three Atmospheric compensation algorithms developed to take
advantage of deep blue band ,near zero reflectance in NIR/SWIR and model based empirical line method (ELM).
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OLI Atmospheric CompensationExperiment 3: Real Data
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Temperature is a driving factor impacting hydrodynamics and therefore materials
transport and water qualityTrue Color Composite Thermal Channel
Cold center
Warm ring
• Hydrodynamic models calibrated with surface thermal maps can help bridge temporal gaps and provide estimates of subsurface behavior
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One Possible Solution to Landsa’st Temporal Resolution
Hydrodynamic modeling, when calibrated, can compensate low temporal resolution ofLandsat
A well‐calibrated model enables pre‐casting and forecasting of the state of the environment
Hydrodynamic models can estimate 3‐D flow and material transport
– Integrate Landsat data with hydrodynamic (HD) modeling
Day 1 Day 16HD
360‐hours gap of imagery
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Hydrodynamic Modeling: Inputs
ALGE Hydrodynamic Model
– Nudging Vectors (hourly).• Whole lake simulation provides nudging vectors for small scale simulation.
Landsat 5: July 13th, 2009Lake Ontario simulation: Surface Currents
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Collaborations for 2012, 2013 & 2014 Field Seasons