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Up Topic Frequently Asked Questions / Data Products & Algorithms FAQ / How to derive RRS from MODIS normalized water leaving radiance (locked)
- By Donna Date 2005-09-15 14:31
Rrs is an output option of msl12 (as distributed in SeaDAS), so you can generate it if you want to process the granule(s) yourself.  Rrs is simply nLw/F0, where F0 is extraterrestrial solar irradiance.  The proper F0 to use will depend on whether the nLw has been corrected for out-of-band response. The nLw of the standard Level-2 products as distributed from this site are corrected from full band to nominal inband (a 10-nm square bandpass centered on the nominal wavelength).  For standard MODIS/Aqua products, here are the F0 numbers to use when normalizing nLw:

wave    F0
412     171.183655
443     188.755463
488     194.179092
531     185.945450
551     186.996353
667     152.439102
678     148.138199
748     127.595451
869      94.873634

These are derived by averaging the Thullier spectrum to a 10-nm square band-pass, centered at the nominal wavelengths of MODIS (actually center +/- 5nm). If one were to process the data with the nLw out-of-band correction disabled, the full band F0 would need to be applied in computing RRs. 
Those are available here:  http://oceancolor.gsfc.nasa.gov/DOCS/RSR_tables.html

If you are processing from Level-1A to Level-2 with msl12 in SeaDAS, then you have the option to output Lw, nLw, and Rrs.  Details about these output products can be found at the links below:
http://oceancolor.gsfc.nasa.gov/DOCS/MSL12/master_prodlist.html/#Lw

http://oceancolor.gsfc.nasa.gov/DOCS/MSL12/master_prodlist.html/#nLw

http://oceancolor.gsfc.nasa.gov/DOCS/MSL12/master_prodlist.html/#Rrs
Up Topic Frequently Asked Questions / Data Products & Algorithms FAQ / How to derive RRS from MODIS normalized water leaving radiance (locked)

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