75% 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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