数据说明
SeaWiFS Remote Sensing Reflectance at 443nm (Rrs443)
上传时间:2019-05-23 00:12:18 浏览次数:作者与来源:admin
The remote-sensing reflectance is a measure of how much of the downwelling radiance that is incident onto the water surface in any direction is eventually returned through the surface into a small solid angle ΔΩ centered on a particular direction (θ,φ).
Unit: sr-1
Resolution:  9km pixel, daily, monthly
Duration : Sep. 1997 to Dec. 2010.
Source: Sea-viewing Wide Field-of-view Sensor(SeaWiFS), NASA
Version: 2018
Processing: Original daily and monthly mean products are shown.
 
In this algorithm, the TOA radiance is assumed to be partitioned linearly into various distinct physical contributions as shown below:
Lt(λ)=[Lr(λ)+La(λ)+tdv(λ)Lf(λ)+tdv(λ)Lw(λ)]tgv(λ)tgs(λ)fp(λ)
where:
λ = 443nm
Lr(λ) = the radiance contribution due to Rayleigh scattering by air molecules
La(λ) = the contribution due to scattering by aerosols, including multiple scattering interactions with the air molecules
Lf(λ) = the contribution from surface whitecaps and foam
Lw(λ) = the water-leaving component
tdv(λ) = the transmittance of diffuse radiation through the atmosphere in the viewing path from surface to sensor
tgv(λ) = the transmittance loss due to absorbing gases for all upwelling radiation traveling along the sensor view path
tgs(λ) = the transmittance to the downwelling solar radiation due to the presence of absorbing gases along the path from Sun to surface
fp(λ) = is an adjustment for effects of polarization.
The atmospheric correction algorithm retrievesLw(λ) by estimating and subtracting the terms on the right-hand side of the above equation fromLt(λ). TheRrs(λ) is then computed as:
Rrs(λ)=(Lw(λ)/(F0fscos(θs)tds)fb(λ)fλ
where:
F0extraterrestrial solar irradiance
fsadjustment of F0 for variation in Earth-Sun distance
fbbidirectional reflectance correction
fλcorrection for out-of-band response
Known issues
1. A limited set of satellite-to-in-situ match-up validation results are available for seaWIFS from the validation tool of the SeaWiFS Bio-Optical Archive and Storage System (SeaBASS). And the result shows a mean bias of 0.00010 and a mean absolute error(MAE) of 0.00105.
2. It is worth noting that the products here are mainly used to estimate the PAR of the global ocean. When estimating the PAR of a regional area, it is necessary to use the measured PAR data to verify the applicability of the products presented here.
Reference
Ziauddin Ahmad, Bryan A. Franz, Charles R. McClain, Ewa J. Kwiatkowska, Jeremy Werdell, Eric P. Shettle, and Brent N. Holben. New aerosol models for the retrieval of aerosol optical thickness and normalized water-leaving radiances from the SeaWiFS and MODIS sensors over coastal regions and Open Oceans. Applied Optics, 2010,49(29):5545-5560. DOI:10.1364/ao.49.005545
Bailey, Sean W., and P. Jeremy Werdell. A multi-sensor approach for the on-orbit validation of ocean color satellite data products. Remote Sensing of Environment, 2006,102(1-2):12-23. DOI:10.1016/j.rse.2006.01.015
Gordon, Howard R., and Menghua Wang. Influence of oceanic whitecaps on atmospheric correction of SeaWiFS. Applied Optics, 1994,33(33):7754-7763. DOI:10.1364/ao.33.007754
Zibordi, G., F. Mélin, and J‐F. Berthon. Comparison of SeaWiFS, MODIS and MERIS radiometric products at a coastal site. Geophysical Research Letters,2006,33(6), L06617. DOI:10.1029/2006gl025778
All the contents of this page are quoted from NASA. All project documentation and related publications can be found at the website: https://oceancolor.gsfc.nasa.gov/