High Resolution MODIS Ocean Color

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High Resolution MODIS Ocean Color
Fred Patt1, Bryan Franz1, Gerhard Meister2, P.
Jeremy Werdell3 NASA Ocean Biology Processing
Group 1Science Applications International
Corporation 2Futuretech Corporation 3Science
Systems and Applications, Inc.
Subframe Striping
band 6 failing on MODIS/Aqua
Concept

• Subframe striping was found in band 3 ocean data
• Analysis of median DN of L1B ocean scenes shows
  subframe striping in bands 1-3, 5 and 7
• MCST indicates effect has been qualitatively
  known

• The goal is to investigate the utility of the
  250 and 500-meter land bands for ocean color
  applications, and to provide that capability to
  SeaDAS users.
• A second goal is to investigate the use of the
  short-wave IR bands for use in atmospheric
  correction (Wang 2005), especially for coastal
  applications, and to provide that capability to
  SeaDAS users.
• The approach is to define a virtual sensor which
  includes all the 250 and 500-meter channels, as
  well as the 1000-meter channels in the visible
  and near IR, at a consistent resolution.
• We call this virtual sensor HIRES MODIS, with
  Aqua and Terra variants known as HMODISA
  HMODIST.

Progress to Date

• The processing software has been modified to read
  the additional MODIS bands, and to allow
  processing at a user-specified spatial resolution
  (250, 500, or 1000-meters).
• Interpolation is used to raise the resolution of
  the lower-resolution bands when working at higher
  resolutions. When processing higher-resolution
  bands at reduced resolution, the Level-1B
  aggregated radiance fields are utilized.
• Geolocation and path geometries are appropriately
  interpolated for the defined processing
  resolution.
• Standard Rayleigh tables have been created for
  the full 16-band suite, and aerosol models have
  been spectrally interpolated.
• A full set of aerosol model tables, specific to
  the band suite, has also been generated, with
  testing now underway.
• Polarization sensitivities have been determined,
  and standard polarization corrections have been
  implemented for all bands.
• An initial vicarious calibration to MOBY has been
  performed.

Band 1
Band 2
Band 4
Band 3
RGB ImageStandard MODISvsHIRES MODIS
Processing Example
Possible Correction Approach
Using fixed aerosol type, with aerosol
concentration from 869-nm band at 250-meter
resolution OC2 chlorophyll algorithm using 469
and 555-nm bands at 500-meter resolution.

• Look-up table of correction vs. radiance to be
  applied to the L1B radiances
• The best method of determining the correction is
  still being worked

1 km
Future Plans

• Improved implementation into MSL12
• add support for thermal bands to allow
  co-registered SST retrievals
• update aerosol model tables
• finalize vicarious calibration
• Investigate use of SWIR bands for atmospheric
  correction
• NIR Lw correction
• aerosol model selection
• Enhance SeaDAS to support HIRES MODIS
• processing and display

250 m
Characteristics of MODIS Visible and NIR Bands
nLw at 645nm
chlorophyll using OC2 algorithm
Band Wavelength
Resolution SNR Ltypical (nm)
(meters)
(W cm-2 mm-1 sr-1) 8 412 1000 880 44.9
9 443 1000 838 41.9 3 469 500 243 35.3
10 488 1000 802 32.1 11 531 1000 754 27.
9 12 551 1000 750 21.0 4 555 500 228 29
.0 1 645 250 128 21.8 13 667 1000
910 9.5 14 678 1000 1087 8.7
15 748 1000 586 10.2 2 859 250 201 24.7
16 869 1000 516 6.2 5 1240
500 74 5.4 6 1640 500 275 7.3
7 2130 500 110 1.0
Acknowledgements
The work presented here is supported by the Ocean
Biology Group (OBPG) at NASA Goddard Space
Flight center, within the NASA Biogeochemistry
Program. We also wish to acknowledge our ongoing
collaboration with the Naval Research Laboratory
(NRL) and the MODIS Characterization Support Team
(MCST).
Wang, M. and W. Shi, Estimation of ocean
contribution at the MODIS near-infrared
wavelengths along the east coast of the U.S.
Two case studies, Geophys. Res. Letters, 32,
2005.
band 6 failing on MODIS/Aqua