MODIS Ocean Products
Entry ID:
MODIS_OCEAN_PARENT
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Summary
Abstract:
The Moderate Resolution Imaging Spectroradiometer (MODIS) is the key instrument aboard the Terra (EOS AM) and Aqua (EOS PM) satellites. It is an optical scanner that views the Earth in 36 channels with spatial resolution ranging from 250 meters to 1 kilometer. MODIS-Aqua Level-2 and Level-3 Ocean Color and Sea Surface Temperature (SST) data products are processed and distributed by the Ocean ... Biology Processing
Group (OBPG) at http://oceancolor.gsfc.nasa.gov/
Ocean color and SST processing details can be found at
http://oceancolor.gsfc.nasa.gov/DOCS/MODISA_processing.html and at
http://oceancolor.gsfc.nasa.gov/DOCS/modis_sst/
SST from MODIS-Terra are available from the Ocean Color Web data archive. For additional information about MODIS ocean data products, see http://oceancolor.gsfc.nasa.gov/
The MODIS-Aqua Level 1A files that are produced, utilized, and distributed by the Ocean Biology Processing Group (OBPG) are subsetted to remove bands and data that are not utilized for Ocean (SST and Ocean Color) product generation. The Level 1B data set contains calibrated and geolocated at-aperture radiances generated from Level 1A sensor counts and GEO files.
Each Level-2 &granule& represents 5 minutes of Terra or Aqua viewing. The ocean
color products are only collected in daylight, resulting in 144 granules per
day. The sea surface temperature products are collected both day and night,
resulting in 288 granules per day. Pixels have 1 km spatial resolution. There
are 1354 pixels across the granule, and 2030 rows down the granule. Each
Level-2 product is generated from the corresponding Level-1B product. Eleven
ocean color parameters and three sea surface temperature parameters are
produced. Each pixel also has up to 32 flags and masks that indicate the
presence of non-ocean data, algorithm failures and warnings.
At Level-3, the products can be generalized into three functional groups:
binned 4.6 km, mapped 4.6 km, and mapped 9 km.
Level-3 binned products are global products. Spatial bins have 4.63 km spatial
resolution in a sinusoidal equal-area grid. Only bins with data values are
present; land bins and bins with no data are not stored in the files. All 11
ocean color parameters and three sea surface temperature parameters are
available in multiple temporal composites (Daily, Weekly, Monthly, Seasonal,
Yearly, Cumulative). Each Level-3 binned Ocean Color granule contains only data
that have met data quality standards as indicated by the Level-2 flags and
masks. SST products can contain data of varying data quality levels, but each
bin will only contain the best quality data available for the time period.
The Level-3 standard mapped products are global products as well. Grid points
for the entire globe are present in the data granules, including fill values
for land and unfilled data points. Spatial resolutions of 4.6 and 9.2 km are
available. Five ocean color parameters and three sea surface temperature
parameters are available in multiple temporal composites (Daily, Weekly,
Monthly, Seasonal, Yearly, Cumulative). Maps are in an equal-angle
latitude-longitude grid (cylindrical equidistant map projection).
Additional products are under evaluation (currently fluorescence line height
and calcite concentration) and are also available as Level 3 mapped products.
See the Algorithm Theoretical Basis Documents (ATBD) at
http://modis.gsfc.nasa.gov/data/atbd/atbd_mod22.pdf and
http://modis.gsfc.nasa.gov/data/atbd/atbd_mod23.pdf
The following are the MODIS ocean parameters:
Parameters 1-6 are normalized water leaving radiances at 412, 443, 488, 531,
551, and 667 nm. These are radiances received at spacecraft altitudes modified
principally by solar irradiance scattering and absorption from the air
(molecular (Rayleigh) scattering), from particles suspended in the air (aerosol
(Mie) scattering), ozone (selective absorption), sea surface reflections (Sun
and sky glitter), and finally, from within the ocean, water molecules and
dissolved and suspended particles. Derived water-leaving radiances normalized
to a constant sun angle, are essential information for the production of most
other MODIS ocean products. The MODIS water-leaving radiance algorithm builds
upon both CZCS and SeaWiFS algorithms, taking advantage of improvements in the
instrument. For more details please see:
http://oceancolor.gsfc.nasa.gov/DOCS/MSL12/
Parameter 7 is the chlorophyll-a concentration. The algorithm used is an
empirical 3-band formulation (OC3M) developed by O'Reilly et al, based on the
maximum ratio of either 443 nm or 488 nm to 551 nm surface reflectance. The
coefficients in the formula are based on analysis of the NASA bio-Optical
Marine Algorithm Data set (NOMAD)
( http://seabass.gsfc.nasa.gov/ ). For more details of the
empirical chlorophyll algorithm please see:
http://oceancolor.gsfc.nasa.gov/cgi/postlaunch_tech_memo.pl?11
Parameter 8 is the ocean water attenuation coefficient, or diffuse attenuation
coefficient at 490 nm (K490). The summary for parameter 7 is relevant here, as
well.
Parameters 9-11 are ocean aerosol properties: aerosol optical thickness (AOT)
at 869 nm (Tau 869), epsilon 748nm/869nm, and angstrom coefficient 531nm/869nm.
AOT is a measure of atmospheric aerosol concentration and the effect that they
have on the transmission of light. Epsilon is an index describing the two
aerosol models selected by the atmospheric correction algorithm. The angstrom
coefficient describes the spectral behavior and size distribution of the
aerosol particles in the AOT.
Sea-surface temperatures are produced as follows: Day using MODIS channels 31
and 32 (11 micron), Night using MODIS channels 31 and 32, and Night using MODIS
channels 22 and 23 (4 micron). SST product determination is based on infrared
retrievals of ocean temperature which are corrected for atmospheric absorption.
Processing details can be found at
http://oceancolor.gsfc.nasa.gov/DOCS/modis_sst/ 
Related URL
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Description:
Browse MODIS-Aqua Level 1 and Level 2 Data Products
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Geographic Coverage
(Click for Interactive Map)
Spatial coordinates
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N: 90.0
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S: -90.0
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E: 180.0
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W: -180.0
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Temporal Coverage
Start Date:
2000-02-18
Start Date:
2002-07-04
Data Resolution
Latitude Resolution:
4 KM, 9 KM
Longitude Resolution:
4 KM, 9 KM
Horizontal Resolution Range:
1 km - < 10 km or approximately .01 degree - < .09 degree
Temporal Resolution:
Monthly Climatology
Temporal Resolution Range:
Monthly Climatology
Data Set Progress
COMPLETE
Personnel
Role:
TECHNICAL CONTACT
Role:
DIF AUTHOR
Phone:
(865) 574-7447
Email:
uso at daac.ornl.gov
Contact Address:
ORNL DAAC User Services Office
Oak Ridge National Laboratory
City:
Oak Ridge
Province or State:
TN
Postal Code:
37831-6407
Country:
USA
Extended Metadata Properties
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Creation and Review Dates
DIF Creation Date:
2003-03-10
Last DIF Revision Date:
2010-09-01
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