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Retrieving Coastal Optical Retrieving Coastal Optical Properties from MERISProperties from MERIS
S. Ladner1, P. Lyon2, R. Arnone2, R. Gould2, T. Lawson1, P. Martinolich1
1) QinetiQ North America, Stennis Space Center, MS 2) Naval Research Laboratory, Stennis Space Center, MS
Objectives
• Compare MERIS Remote Sensing Reflectance and Optical Properties in a variety of clear and turbid water types under varying atmospheric conditions using two different atmospheric correction approaches.
• Compare MERIS and MODIS-Aqua optical properties.
• Validate MERIS and MODIS-Aqua Remote Sensing Reflectances using insitu measurements.
MERIS sensor on ESA ENVISAT Band set similar to MODIS / SeaWiFS 1000m & 300m resolution
ENVISAT
MERIS Sensor
Operational MERIS Processing in NRL’s Automated Processing System (APS):
- Input ESA Level-1 / Level-2 Data
Level 1 = Calibrated and Geo-Located
Level 2 = Atmospherically Corrected Radiances and Derived
In-Water Products
- Output Bio-Optical Properties (Chlorophyll, Absorption, Scattering, Navy Products, Etc.)
Modifications to APS for MERIS Level-1 Processing to use the same Atmospheric Correction used for SeaWiFS and MODIS processing (Gordon/Wang with NIR Iteration)Created the Relative Spectral Response (RSR) Tables
Created the software to read in MERIS N1 (Level-1) data from ESA
Modified L2GEN / N2GEN to handle MERIS data.
Obtained MERIS Rayleigh Tables from Goddard
Obtained MERIS Aerosol Tables from Goddard
Created scripts, area/info programs to handle MERIS N1 data from ESA
*** Provided Software for Level-2 Processing (L2GEN) to NASA Goddard
NRL hosted a Navy/NOAA /NASA and University Study Group working to assess MERIS data.
Monterey Bay, CA June 19, 2008 18:23 GMT
-.03 -.018 -.006 .006 .018 .03
Rrs (1/sr)
-.01 -.006 -.002 .002 .006 .01
Rrs Difference (1/sr)
.0005 .002 .008 .032 .13 .5
Bb (1/m)
True Color
Rrs 490nm Bb 560nm (QAA) Difference (ESA-NRL)
Rrs490
Bb560
(QAA)
ESA
NRL
ESA
NRL
Inputs to APS:
ESA = Level2NRL = Level1
Less Atmospheric
Failures
Monterey Bay – Scatter Plots
1:1 1:1
1:1 1:1
1:1
Inputs to APS:
ESA = Level2NRL = Level1
Yellow SeaOctober 10, 2008 02:24 GMT
-.03 -.018 -.006 .006 .018 .03
Rrs (1/sr)
-.01 -.006 -.002 .002 .006 .01
Rrs Difference (1/sr)
.0005 .002 .008 .032 .13 .5
Bb (1/m)
True Color
Rrs 510nm Bb 560nm (QAA) Difference (ESA – NRL)
Rrs510
Bb560
(QAA)
ESA
NRL
ESA
NRL
Inputs to APS:
ESA = Level2NRL = Level1
Less Atmospheric
Failures
Yellow Sea – Scatter Plots
1:1 1:1
1:1 1:1
1:1
Inputs to APS:
ESA = Level2NRL = Level1
Gulf of California, CA July 22, 2008 17:47 GMT
-.03 -.018 -.006 .006 .018 .03
Rrs (1/sr)
-.01 -.006 -.002 .002 .006 .01
Rrs Difference (1/sr)
.0005 .002 .008 .032 .13 .5
Bb (1/m)
True Color
Rrs 443nm Bb 560nm (QAA) Difference (ESA-NRL)
Rrs443
Bb560
(QAA)
ESA
NRL
ESA
NRL
Inputs to APS:
ESA = Level2NRL = Level1
Less Atmospheric
Failures
Gulf of California – Scatter Plots
1:1 1:1
1:1 1:1
1:1
Inputs to APS:
ESA = Level2NRL = Level1
Martha’s Vineyard (MVCO) October 04, 2008 15:37 GMT
-.03 -.018 -.006 .006 .018 .03
Rrs (1/sr)
-.01 -.006 -.002 .002 .006 .01
Rrs Difference (1/sr)
.0005 .002 .008 .032 .13 .5
Bb (1/m)
True Color
Rrs 560nm Bb 560nm (QAA) Difference (ESA-NRL)
Rrs560
Bb560
(QAA)
ESA
NRL
ESA
NRL
Inputs to APS:
ESA = Level2NRL = Level1
Less Atmospheric
Failures
Martha’s Vineyard – Scatter Plots
1:1 1:1
1:1 1:1
1:1
Inputs to APS:
ESA = Level2NRL = Level1
MERIS vs. MODIS (NRL)March 20, 2008 16:04 GMT
MERIS Bb 560nm (QAA) MODIS Aqua Bb 555nm (QAA)
Difference (MERIS – MODIS)
-.01 -.006 -.002 .002 .006 .01
Bb Difference (1/sr)
.0005 .002 .008 .032 .13 .5
Bb (1/m)
Which OneIs More
Accurate?
MERIS vs. MODIS (NRL)March 20, 2008 16:04 GMT
MERIS Bb 560nm (QAA) MODIS Aqua Bb 555nm (QAA) Difference (MERIS – MODIS)
-.01 -.006 -.002 .002 .006 .01
Bb Difference (1/sr)
.0005 .002 .008 .032 .13 .5
Bb (1/m)
Which OneIs More
Accurate?
MERIS vs. Insitu Rrs @ 490nm (Scatter Plots)
MERIS ESA = 20 Match-ups MERIS NRL = 32 Match-ups
StationLocations
Northern Gulf of MexicoMonterey Bay, CA
MODIS NRL = 42 Match-ups
More RetrievalsBetter Rrs
Better IOP’s
R2 = 0.01Ratio = 2.47
N = 20Y=0.05x+0.004
R2 = 0.42Ratio = 2.44
N = 32Y=0.49x+0.001
R2 = 0.10Ratio = 2.27
N = 42Y=0.24x+0.002
MERIS vs. Insitu Rrs @ 560nm (Scatter Plots)
MERIS ESA = 19 Match-ups MERIS NRL = 32 Match-ups
StationLocations
Northern Gulf of MexicoMonterey Bay, CA
MODIS NRL = 42 Match-ups
R2 = 0.36Ratio = 2.45
N = 19Y=0.29x+0.001
R2 = 0.70Ratio = 1.71
N = 32Y=0.78x-0.001
R2 = 0.44Ratio = 1.95
N = 42Y=0.47x+0.001
More RetrievalsBetter Rrs
Better IOP’s
Summary
• Atmospheric Correction Failures are more significant in MERIS ESA processing (Coastal and Offshore).
• Remote Sensing Reflectances and Backscattering estimates from MERIS ESA vs. NRL processing schemes produce similar results.
• Backscattering estimates from NRL MERIS processing are lower in coastal regions.
• MERIS Satellite and In-situ Match-ups for Remote Sensing Reflectance are better using NRL processing scheme compared to MERIS from ESA processing and MODIS-Aqua.
Questions?
