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                                                                                        High Resolution MODIS Ocean Color
                                                                                             Fred          Patt1,          Bryan       GerhardFranz 1, P. Jeremy           Meister2,                                 Werdell3

                                                                                                                           NASA Ocean Biology Processing Group
                                                                                                                                       1Science    Applications International Corporation
                                                                                                                                                     2Futuretech Corporation
               * band 6 failing on MODIS/Aqua
                                                                                                                                                                                                                                                                           Subframe Striping
                                                                                                                                              3Science Systems and Applications, Inc.

                                                                                                                                                                                                                                                          • Subframe striping was found in
                                  Concept                                                                                                                                                                                                                   band 3 ocean data
                                                                                                                                                                                                                                                          • Analysis of median DN of L1B
  •            The goal is to investigate the utility of the 250 and 500-meter land
                                                                                                                                                                                                                                                            ocean scenes shows subframe
               bands for ocean color applications, and to provide that capability to
               SeaDAS users.
                                                                                                                                                                Progress to Date                                                                            striping in bands 1-3, 5 and 7
                                                                                                                                                                                                                                                          • MCST indicates effect has
  •            A second goal is to investigate the use of the short-wave IR bands for                                                                                                                                                                       been qualitatively known
               use in atmospheric correction (Wang 2005), especially for coastal             • The processing software has been modified to read the additional MODIS bands, and to allow processing at a user-specified spatial
               applications, and to provide that capability to SeaDAS users.                   resolution (250, 500, or 1000-meters).
                                                                                                                                                                                                                                                              Band 1                                   Band 2
  •            The approach is to define a virtual sensor which includes all the 250         • Interpolation is used to raise the resolution of the lower-resolution bands when working at higher resolutions. When processing higher-
               and 500-meter channels, as well as the 1000-meter channels in the               resolution bands at reduced resolution, the Level-1B aggregated radiance fields are utilized.
               visible and near IR, at a consistent resolution.

  •            We call this virtual sensor HIRES MODIS, with Aqua and Terra variants         • Geolocation and path geometries are appropriately interpolated for the defined processing resolution.
               known as HMODISA & HMODIST.
                                                                                             • 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.
                                                                                                                                                                                                                                                              Band 3                                   Band 4

                                                                                             • Polarization sensitivities have been determined, and standard polarization corrections have been implemented for all bands.
  RGB Image
                                                                                             • An initial vicarious calibration to MOBY has been performed.
Standard MODIS
      vs
 HIRES MODIS

                                                                                                              Processing Example
                                                                                            Using fixed aerosol type, with aerosol concentration from 869-nm band
                                                                                                            at 250-meter resolution                                                                                                                         Possible Correction Approach
                                                                                            OC2 chlorophyll algorithm using 469 and 555-nm bands at 500-meter
                                                                                                                                                                                                                                                      •                Look-up table of correction vs. radiance to
                                                                                                           resolution.
                                                                                                                                                                                                                                                                       be applied to the L1B radiances
                                                                                                                                                                                                                                                      •                The best method of determining the
      1 km                                                                                                                                                                                                                                                             correction is still being worked




                                                                                                                                                                                                                                                                           Future Plans
                                                                                                                                                                                                                                         •                 Improved implementation into MSL12
                         250 m
                                                                                                                                                                                                                                                              –         add support for thermal bands to allow co-
                                                                                                                                                                                                                                                                        registered SST retrievals
                                                                                                                                                                                                                                                              –         update aerosol model tables
                                                                                                                                                                                                                                                              –         finalize vicarious calibration
             Characteristics of MODIS Visible and NIR Bands
                                                                                        nLw at 645nm                                                                   chlorophyll using OC2 algorithm                                   •                 Investigate use of SWIR bands for atmospheric correction
      Band     Wavelength        Resolution          SNR              Ltypical
                                                                                                                                                                                                                                                               –         NIR Lw correction
                 (nm)             (meters)                        (W cm-2 mm-1 sr-1)
       8           412              1000             880              44.9                                                                                                                                                                                     –         aerosol model selection
       9           443              1000             838              41.9
       3           469              500              243              35.3
                                                                                                                                                                                                                                         •                 Enhance SeaDAS to support HIRES MODIS
      10           488              1000             802              32.1
      11           531              1000             754              27.9                                                                                                                                                                                    –       processing and display
      12           551              1000             750              21.0
       4           555              500              228              29.0
       1           645              250              128              21.8
      13
      14
                   667
                   678
                                    1000
                                    1000
                                                      910
                                                     1087
                                                                      9.5
                                                                      8.7
                                                                                                                                                                                                                                                                 Acknowledgements
      15           748              1000             586              10.2                                                                                                                                                                   The work presented here is supported by the Ocean Biology Group (OBPG)
       2           859              250              201              24.7                                                                                                                                                                   at NASA Goddard Space Flight center, within the NASA Biogeochemistry Program.
      16           869              1000             516              6.2                                                                                                                                                                    We also wish to acknowledge our ongoing collaboration with the Naval Research
       5           1240             500              74               5.4                                                                                                                                                                    Laboratory (NRL) and the MODIS Characterization Support Team (MCST).
       6           1640 *           500              275              7.3
       7           2130             500              110              1.0
                                                                                                                                                                                                                                             Wang, M. and W. Shi, “Estimation of ocean contribution at the MODIS near-infrared
                          * band 6 failing on MODIS/Aqua                                                                                                                                                                                     wavelengths along the east coast of the U.S.: Two case studies”, Geophys. Res.
                                                                                                                                                                                                                                             Letters, 32, 2005.

								
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