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GES DISC updates Giovanni Ocean Color Radiometry portal

New products include remote sensing reflectances and fluorescence; ocean data now available at 4km spatial resolution

GES DISC updates Giovanni Ocean Color Radiometry portal

MODIS-Aqua 4km resolution normalized Fluorescence Line Height (nflh) image of the coast of Brazil near the mouth of the Amazon River, in May 2005.

GES DISC updates Giovanni Ocean Color Radiometry portal

We have just finished adding current MODIS-Aqua data products at both 4 and 9 kilometer spatial resolution (monthly temporal resolution) to our Ocean Color Radiometry Giovanni data portal. This update is an element of our NASA-funded Water Quality for Coastal and Inland Waters project (PI: Zhongping Lee;  Co-I: James Acker).  Several other Co-Is are involved with this project, which is working on the refinement of data products for particular application to coastal and inland waters.

 
This update is significant for several reasons:
  • One, this is the first time that 4km spatial resolution data ocean color data products have been available in Giovanni.   (Please be aware that processing times will be slower with this higher spatial resolution data set.)  
  • Two, the new MODIS data products include all remote-sensing reflectances (Rrs), as well as MODIS-Aqua particulate inorganic carbon (PIC), particulate organic carbon (POC), Photosynthetically Available Radiation (PAR), and normalized fluorescence line height (nflh).  
  • Three, we have changed the file-naming convention in the Giovanni system so that we will be able to quickly update the data archive when the Ocean Biology Processing Group performs a data reprocessing.

 

Also, the MODIS-Aqua data is now updated to the most recent month available, currently February 2011.

Shown below are sample images of the new 4km resolution data products for the coastal region of Brazil near the mouth of the Amazon River, for the month of May 2005.    To see the full-size version of each image, just click on the image.  The utilization of these images and data in investigations of can aid the analysis of the contributions of phytoplankton, organic matter, sediments, and detritus to the optical characteristics of oceanic waters.

Mouth of Amazon, May 2005, 4km chlorophyll dataMODIS-Aqua 4 km resolution chlorophyll a image of the coast of Brazil near the mouth of the Amazon River, in May 2005.   The coastal current loops out to sea north of the Amazon River mouth, carrying a plume of sediments, organic matter, phytoplankton, and other marine constituents out to sea.                                          
Mouth of the Amazon, May 2005, 4km, CDOM Index

 

 

MODIS-Aqua 4km resolution CDOM Index image of the coast of Brazil near the mouth of the Amazon River, in May 2005.  The CDOM Index is based on the algorithm of Morel and Gentili (2009), and indicates the contribution of colored dissolved organic matter to the observed ocean color radiometric properties of ocean waters.

 


 

Mouth of Amazon, May 2005, 4km normalized fluorescence line heightMODIS-Aqua 4km resolution normalized Fluorescence Line Height (nflh) image of the coast of Brazil near the mouth of the Amazon River, in May 2005.  Fluorescence line height is a measure of chlorophyll fluorescence, which indicates the efficiency of photosynthesis.  It is thus diagnostic of both the presence of living phytoplankton and their physiological fitness. 
Mouth of Amazon, May 2005, 4km Particulate Organic CarbonMODIS-Aqua 4km resolution Particulate Organic Carbon (POC) image of the coast of Brazil near the mouth of the Amazon River, in May 2005.  POC indicates the presence of both living and non-living organic particles in the oceanic water column.
Mouth of Amazon, May 2005, 4km remote sensing reflectance at 412nmMODIS-Aqua 4km resolution Remote Sensing Reflectance  at 412 nm (Rrs412) image of the coast of Brazil near the mouth of the Amazon River, in May 2005.   Certain forms of organic matter in the ocean, notably Gelbstoff ("yellow substance") absorb strongly at this wavelength.   Thus, lower values of Rrs412 indicate the presence of light-absorbing organic matter.

 

Reference

Andre Morel and Bernard Gentili (2009): A simple band ratio technique to quantify the colored dissolved and detrital organic material from ocean color remotely sensed data, Remote Sensing of Environment, 113 (5), 998-1011, DOI: 10.1016/j.rse.2009.01.008.

 

 

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Last updated: Apr 12, 2011 03:14 PM ET
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