NORTH ATLANTIC REMOTE SENSING
REFLECTANCES, ATTENUATION
COEFFICIENT AT 490NM, AND
INHERENT OPTICAL PROPERTIES
FROM SATELLITE OBSERVATIONS
PRODUCT IDENTIFIER
OCEANCOLOUR_ATL_OPTICS_L3_NRT_OBSERVATIONS_009_034
GEOGRAPHICAL COVERAGE
Areas :
iberian-biscay-irish-seas
north-west-shelf-seas
66
-46
13
20
VARIABLES
volume_attenuation_coefficient_of_downwelling_radiative_flux_in_sea_water
(KD)
surface_ratio_of_upwelling_radiance_emerging_from_sea_water_to_downwelling_r
(RRS)
volume_absorption_coefficient_of_radiative_flux_in_sea_water_due_to_dissolved_o
(ADG (CDM))
volume_absorption_coefficient_of_radiative_flux_in_sea_water_due_to_phytoplankt
(APHY)
volume_absorption_coefficient_of_radiative_flux_in_sea_water
(ATOT)
mass_concentration_of_suspended_matter_in_sea_water (SPM)
OBSERVATION/MODELS
satellite-observation
PRODUCT TYPE
near-real-time
PROCESSING LEVEL
L3
DATA ASSIMILATION
undefined
SPATIAL RESOLUTION
1km x 1km
VERTICAL COVERAGE (m)
Surface
COORDINATE REFERENCE
SYSTEM
WGS 84 / Plate Carree (EPSG 32662)
FEATURE TYPE
Grid
TEMPORAL COVERAGE
from 2016-01-01 to Present
TEMPORAL RESOLUTION
daily-mean
UPDATE FREQUENCY
daily
PRODUCTION UNIT
OC-PML-PLYMOUTH-UK
Generated on Monday 31st of July 2017 01:11:38 PM
NORTH ATLANTIC REMOTE SENSING REFLECTANCES, ATTENUATION COEFFICIENT AT 490NM,
AND INHERENT OPTICAL PROPERTIES FROM SATELLITE OBSERVATIONS
Short description:
For the North Atlantic ocean, PML's Inherent Optical Properties model, Remote Sensing Reflectances, and
attenuation coefficient of light at 490 nm is operationally produced by the Plymouth Marine Laboratory
Remote Sensing Group in Plymouth, United Kingdom. Daily products for MODIS and VIIRS are available in
Near Real Time (NRT) and few days after in Delayed Time (DT). DT is of better quality as it uses hindcast
meteorological and navigational data. A CCI-based product provides daily data in DT.
Detailed description:
Products ADG (volume absorption coefficient of radiative flux in sea water due to dissolved organic matter
and non algal particles), APH (volume absorption coefficient of radiative flux in sea water due to
phytoplankton) and ATOT (volume absorption coefficient of radiative flux in sea water) are described in the
PML Inherent Optical Property model (Smyth, T.J., Moore, G.F., Hirata, T. Aiken, J. (2006), a semi-analytic
model for the derivation of ocean color inherent optical properties. The RRS product is defined as the
spectral ratio of upwelling radiance and downwelling irradiance which can also be expressed as the ratio of
normalized water leaving Radiance (nLw) and the extra-terrestrial solar irradiance (F0). The KD490 product
identifies the turbidity of the water column, i.e., how visible light in the blue-green region of the spectrum
penetrates within the water column. It is directly related to the presence of scattering particles in the water
column. Inorganic Suspended Particulate Matter (SPM) is defined as all inorganic matter that stays on a
glass fibre filter with an approximate pore size of 0.7 micrometres. Heavy metals and various organic
micropollutants adsorb to SPM, the transport of which can affect the ecosystem. High concentrations of SPM
cause turbidity which in turn affects the underwater light conditions, thus influencing primary production by
phytoplankton and other algae in coastal waters. Products derived from MODIS-Aqua are: Remote sensing
reflectance, (412, 443, 488, 531, 547 and 667 nm.), Inherent Optical Properties, IOPs (IOPADG, APH,
ATOT), SPM and KD490. From VIIRS are derived Rrs (410, 443, 486, 551, and 671 nm), SPM and KD490.
From the CCI multiple-sensor product are derived Rrs (410, 443, 490, 510, 555, 670nm)
Processing information:
PML's Remote Sensing Group has the capability to automatically receive, archive, process and map global
data from multiple polar-orbiting sensors in both near-real time and delayed time. Raw MODIS and VIIRS
data is processed up to Level-3 with the SeaDAS software package available from NASA website. PML's
Remote Sensing Group collects raw data from the upstream providers (Dundee station) as soon as they are
available (Near Real Time). Delayed Time processing mode is performed some days after satellite
overpasses as soon as ancillary data are made available for downloading from NASA's FTP server.
Standard masking criteria for detecting clouds or other contamination factors are routinely applied, i.e., land,
cloud, sun glint, atmospheric correction failure, high total radiance, large solar zenith angle (70deg), large
spacecraft zenith angle (56deg), coccolithophores, negative water leaving radiance, and normalized water
leaving radiance at 555 nm 0.15 Wm-2 sr-1 (McClain et al., 1995). These products are remapped at nominal
1.2 Km spatial resolution using cylindrical equirectangular projection. The CCI products use the same
process as the REP (see description there)
Description of observation methods/instruments:
Ocean colour technique exploits the emerging electromagnetic radiation from the sea surface in different
wavelengths. The spectral variability of this signal defines the so called ocean colour which is affected by the
presence of phytoplankton. By comparing reflectances at different wavelengths and calibrating the result
against in-situ measurements, an estimate of in water absorption parameters can be derived.
Generated on Monday 31st of July 2017 01:11:38 PM
Quality / Accuracy / Calibration information:
Detailed description of cal/val is given in the relevant QUID, associated validation reports and quality
documentation.'
Suitability, Expected type of users / uses:
This product is meant for use for educational purposes and for the managing of the marine safety, marine
resources, marine and coastal environment and for climate and seasonal studies.
References:
McClain, C. R., Arrigo, K. R., Esaias, W., Darzi, M., Patt, F. S., Evans, R. H., et al.(1995). SeaWiFS
Algorithms, Part 1. NASA Tech. Memo. 104566, Vol. 28 Greenbelt, Maryland: NASA Goddard Space Flight
Center.Smyth, T.J., Moore, G.F., Hirata, T. Aiken, J. (2006) PML Inherent Optical Property model.
Semianalytical model for the derivation of ocean color inherent optical properties: description,
implementation, and performance assessment. Applied Optics, 45(31), 8116-8131."
Generated on Monday 31st of July 2017 01:11:38 PM