GSM
Contents
GSM Products Family Description
The ocean color products available here were made using Level 3, daily, binned imagery from SeaWiFS, MODIS-Aqua, Meris, and Viirs. The products themselves are 9km if SeaWiFS is involved, 4km otherwise, daily, 8-day and monthly imagery of GSM products, confidence intervals and coverage maps. The products were generated using the Garver-Siegel-Maritorena (GSM) model described in:
Maritorena S., D.A. Siegel & A. Peterson. 2002. Optimization of a Semi-Analytical Ocean Color Model for Global Scale Applications. Applied Optics. 41(15): 2705-2714.
When multiple sensors are used, the GSM model uses the remote-sensing reflectance (Rrs) from all available sources over a given bin of the L3 grid as described in:
Maritorena, S. and D.A. Siegel. 2005. Consistent Merging of Satellite Ocean Color Data Sets Using a Bio-Optical Model. Remote Sensing of Environment, 94(4): 429-440.
Maritorena S., O. Hembise Fanton d?Andon, A. Mangin, D.A. Siegel. 2010. Merged Satellite Ocean Color Data Products Using a Bio-Optical Model: Characteristics, Benefits and Issues. Remote Sensing of Environment, 114, 8: 1791-1804 (doi: 10.1016/j.rse.2010.04.002). pdf
File Naming convention:
For daily files:
Prod_name.YearDay.L3[b|m]_DAY.Sat_combo.Proc_vers.Type
Prod_name:
----------
GSMchl (Chlorophyll concentration) GSMacdm (Dissolved and detrital organic matter absorption coefficent at 443 nm) GSMbbp (Particulate backscattering coefficient at 443 nm) GSMChl_sig (Confidence interval of the Chl product) GSMacdm_sig (Confidence interval of the acdm product) GSMbbp_sig (Confidence interval of the bbp product) GSMcovMask (Coverage map) GSMbin (all the above in ISIN Grid bin format, instead of plate carrée mapped images) mapped products are 2160x4320 for combinations that include SeaWiFS, all others 4320x8640(4km)
bin format is ISIN grid index and the products for the bin. http://oceancolor.gsfc.nasa.gov/cms/L3Bins.html 1/12deg bin boundaries (9km) for SeaWiFS and 1/24 deg (4km) for all others.
Year:
-------
Year in yyyy format
Day
-------
Day in ddd format (i.e. sequential day of the year)
Sat_combo
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Describes which sensor or combination of sensors were used to produce the data:
01 SeaWiFS only
02 or 'A' Aqua only ('A' is used 2012 and on)
04 Meris only (else 'M')
V Viirs only
07 SeaWiFS, Aqua, and Meris
AV Aqua and Viirs
AM Aqua and Meris
Proc_vers
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Refers to the version of the data (current processing is 8 associated with the Aqua R2014.0 reprocessing effort http://oceancolor.gsfc.nasa.gov/WIKI/OCReproc20140MA.html with Meris R2012.1 http://oceancolor.gsfc.nasa.gov/cms/reprocessing/OCReproc20121ME.html) Version 6 is associated with the R2010 reprocessing effort (http://oceancolor.gsfc.nasa.gov/WIKI/OCReproc20100MA.html. The latest processing versions can be found here http://oceancolor.gsfc.nasa.gov/cms/reprocessing.
Type
-------
Descibes the type of file (HDF or PNG)
Examples of a daily file name:
GSMbbp.2008009.L3m_DAY.02.8.hdf Aqua bbp
GSMchl.2008009.L3m_DAY.07.8.hdf Seawifs Aqua Meris merged chl
GSMcovMask.2008009.L3m_DAY.07.8.hdf Seawifs Aqua Meris coverage
GSMchl_sig.2012005.L3m_DAY.AV.8.png Aqua Viirs merged chl confidence interval
GSMchl.2014013.L3m_DAY.V.8.hdf Viirs chl
GSMchl.2012013.L3m_DAY.06.8.hdf Aqua Meris merged chl
GSMbin.2012013.L3b_DAY.04.8.hdf Meris bin file
For 8 day and monthly data
Prod_name.SYearSDayEYearEDay_ID.L3[b|m].Sat_combo.Proc_vers.Type
Definitions of Prod_name, Sat_combo, Proc_vers and Type are identical to those for the daily files
YearFDayYearLDay
-----------
Year (in yyyy format)
First day (in ddd format, i.e. sequential day of the year) of daily data used to create the composite image.
Year (in yyyy format)
Last day (in ddd format) of daily data used to create the composite image.
_ID
-----
is "_8D" for 8 Day and "_MO" for Monthly data.
Examples of composite images names
GSMbbp.20080012008031.L3m_MO.07.8.png Jan-2008 bbp from Seawifs Aqua Meris
GSMbbp.20083362008366.L3m_MO.04.8.hdf Dec 2008 bbp from Meris
GSMbin.20080012008008.L3b_8D.02.8.hdf 8 day composite (days 1-8) from Aqua
GSMchl.20031852003192.L3b_8D.01.6.hdf 8 day composite (days185-192) SeaWiFS chl
The data products are available in HDF (Hierarchical Data Format) files. Each product is represented in a 4320 x 2160 array. For each time period considered (Day, 8D, Monthly) there is one HDF file per product. HDF files are compressed and will self extract when opening. PNG images are also available for browsing purposes.
Product Units:
Chlorophyll-a mg m-3 acdm443 m-1 bbp443 m-1 ci_Chloriphyll-a_sig mg m-3 ci_acdm443 m-1 ci_bbp443 m-1
Data (links to FTP site)
Acknowledgments & Citation
If you use the GSM products for a work that appears in a publication, please give proper credit to our work by citing the 2010 RSE paper:
Maritorena S., Hembise Fanton d’Andon O., Mangin A., Siegel D.A. 2010. Merged Satellite Ocean Color Data Products Using a Bio-Optical Model: Characteristics, Benefits and Issues. Remote Sensing of Environment, 114, 8: 1791-1804 (doi: 10.1016/j.rse.2010.04.002).pdf
and/or by mentioning the source of the data in the "Methods" section or the acknowledgements with something like:
The satellite CHL (and/or CDM and/or BBP) data were obtained from the Ocean Color MEaSUREs project at UCSB (http://wiki.icess.ucsb.edu/measures/Products).
Metadata
- GSM01 Validation Results
Matchups using daily level-3 data (see Maritorena et al., 2010).
- (recent results TBA)
Software
References
Maritorena S., O. Hembise Fanton d’Andon, A. Mangin, D.A. Siegel. 2010. Merged Satellite Ocean Color Data Products Using a Bio-Optical Model: Characteristics, Benefits and Issues. Remote Sensing of Environment, 114, 8: 1791-1804 (doi: 10.1016/j.rse.2010.04.002). pdf
Maritorena, S., and D.A. Siegel, 2005: Consistent merging of satellite ocean color data using a semi-analytical model, Remote Sensing of the Environment, 94, 429-440. pdf
Siegel, D.A., Maritorena, S., Nelson, N.B., Hansell, D.A., Lorenzi-Kayser, M., 2002. Global distribution and dynamics of colored dissolved and detrital organic materials. Journal of Geophysical Research, 107, 3228, doi:10.1029/2001JC000965. pdf
Maritorena, S., D.A. Siegel and A.R. Peterson, 2002: Optimization of a semianalytical ocean color model for global-scale applications. Applied Optics-LP, 41, 2705-2714. pdf
Garver, S.A., and D.A. Siegel, 1997: Inherent optical property inversion of ocean color spectra and its biogeochemical interpretation: I. Time series from the Sargasso Sea. Journal of Geophysical Research., 102, 18,607-18,625. pdf
