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

0

0.2

0.4

0.6

0.8

1

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

050

100150200250300350

0 1 2 3 4 5 6

Band numbers

Mea

n/St

d OLI

L7

7

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