Ocean Color SeaWIFS ProductsEntry ID: gov.noaa.class.OC
Abstract: ABSTRACT: NOAA CoastWatch produces near real-time ocean color products, e.g. chlorophyll-a concentration and turbidity (reflectance), with data from NASA's GeoEye's Orbview-2 satellite (via contractual purchase). The data is collected by selected HRPT ground stations. The level 1A data consists of raw radiance counts from eight bands (six in visible and two in near infrared spectrum), calibration ... data, navigation data, instrument telemetry and selected spacecraft telemetry. Each level 2 satellite specific product has unique characteristics dependent on the sensor and the algorithm applied. While level 2 historic data is open to the public, level 1 data is restricted to users covered by SeaWIFS CoastWatch contract due to limitations associated with commercial data. Users may find instructions on how to become registered users with SeaWIFS at http://coastwatch.noaa.gov/cw_faq.html#ocean%20color.
CURRENTNESS REFERENCE: upon processing
SPATIAL DATA ORGANIZATION INFORMATION
Direct Spatial Reference: Raster
Fees: Free for users covered by CoastWatch contract for online access. For delivery on physical media, users are responsible for the cost of the physical media and production and delivery of the product.
Purpose: PURPOSE: The purpose of SeaWiFS data is to examine oceanic factors that affect global change and to assess the oceans' role in the global carbon cycle, as well as other biogeochemical cycles, through a comprehensive research program. SeaWiFS data are being used to help clarify the magnitude and variability of chlorophyll and primary production by marine phytoplankton and to determine the distribution and timing of spring blooms, i.e., the time of highly abundant growth.
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Data Set Citation
Dataset Originator/Creator: DOC/NOAA/NESDIS/CWP > CoastWatch Program, NESDIS, NOAA, U.S. Department of CommerceNASA/GSFC/ESED/GCDC/GES-DISC > Goddard Earth Sciences, Data and Information Services Center, Global Change Data Center, Earth-Sun Exploration Division, Goddard Space Flight Center, NASA
Dataset Title: Ocean Color SeaWIFS Products
Dataset Release Date: 1997-09-04Online Resource: http://www.class.noaa.gov/nsaa/products/search?sub_id=0&datatype_fa...
Start Date: 1997-09-04
Quality ATTRIBUTE ACCURACY REPORT: Ocean Color values are accurate to within 10 percent. NOAA CoastWatch performs validation of the data through buoy match-ups or other in situ measurements for adjusting processing algorithms as necessary. Chlorophyll values (.001 - 64.767 micrograms per liter) in GeoTIFFs are scaled to 1 to 100. The current turbidity product is the remote sensing reflectance for band 5 ... (555 nm). It provides a good measure of turbidity related to sediment over a range of water clarity and provides a measure of the sediment load in the water. (In oceanography, turbidity is a catch-all term for poor water clarity or visibility. Visibility, as measured with a Secchi disk, is influenced by absorption, but driven mostly by the sediment load. To confuse this issue, water clarity is based on the diffuse light attenuation, which is strongly influenced by absorption as well as scattering, and efforts are being made to determine attenuation coefficients for SeaWiFS.) Chlorophyll-related pigments have little influence on the reflectance at 555 nm. Because of the low absorption by water, band 5 is extremely sensitive to changes in sediment concentration. (Certain phytoplankton groups, such as coccolithophores, are highly scattering, so they produce strong signals in this band). Under extremely high pigment loads (especially dissolved pigments and detrital, non-algal, pigments), band 5 is less effective, because the absorption is a significant part of the signal, potential causing a reduction in the reflectance. Because of the low absorption by water, band 5 can "see" the bottom in relatively clear water. In very clear water, it can detect sand bottom in 20-30 m. In areas where turbidity events are common, the bottom signal would be the minimum reflectance observable. SeaWiFS band 6 (670 nm) is less sensitive to dissolved and detrital pigments, and does not detect the bottom in more than ~6 m, but does not provide the sensitivity of band 5 for clearer water.
LOGICAL CONSISTENCY REPORT: Research and monitoring programs are generally interested in the live phytoplankton biomass and the suspended sediment concentration. The chlorophyll algorithms for SeaWiFS provide a relationship between SeaWiFS bands and standard measurements of chlorophyll for live phytoplankton biomass. For sediment concentrations, a measure of scatter provides the best information. At present, experimental backscattering algorithms exist, additional work needs to be done to validate these algorithms. As an alternative, using the remote sensing reflectance for bands that are most sensitive to scatter (and least sensitive to absorption), provides the best characterization of suspended sediments. Trials have been made of algorithms that determine backscatter. Ultimately, the calculated backscatter will be the best method of describing turbidity. Several factors determine water clarity: absorption due to live phytoplankton, absorption due to dissolved pigments, absorption due to detrital pigments, and scattering due to particulates (mostly inorganic sediments).
COMPLETENESS REPORT: tbd
HORIZONTAL POSITIONAL ACCURACY REPORT: Ocean Color products are generally within 1000 meters.
PROCESS DESCRIPTION: NOAA obtains Level-1A data from GeoEye (formerly ORBIMAGE) and processes the data to Level-2 ocean products using NASA SeaDAS and NOAA algorithms.
PROCESS DATE: Not complete
Access Constraints ACCESS CONSTRAINTS: http://coastwatch.noaa.gov/cw_faq.html#ocean%20color
DISTRIBUTION LIABILITY: Disclaimer - While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by any errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.
Use Constraints Publications of research results utilizing these data must acknowledge the SeaWiFS Project and the Ocean Biology Processing Group (OBPG) at the NASA Goddard Space Flight Center, Greenbelt, MD, USA.
Data Set Progress
Role: TECHNICAL CONTACT
Phone: (301) 763-8209 x 347
Email: Heng.Gu at noaa.gov
5200 Auth Rd Rm 601
City: Camp Springs
Province or State: MD
Postal Code: 20746
Role: DIF AUTHOR
Phone: (303) 497-5099
Fax: (303) 497-6513
Email: Anna.Milan at noaa.gov
325 Broadway, Mail Code E/GC4
Province or State: CO
Postal Code: 80305-3328
Creation and Review Dates
DIF Creation Date: 2008-10-07
Last DIF Revision Date: 2011-11-02