Atmospheric correction of ocean color imagery in the Earth Observing System era

Gordon, Howard R.

doi:10.1029/96jd02443

Cited by 614 publications

(385 citation statements)

References 64 publications

(44 reference statements)

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“…This is known as atmospheric correction [Gordon, 1997]. Typically, the top of the atmosphere (TOA) reflectance r t (l) can be linearly partitioned into various physical contributions [Gordon and Wang, 1994]:…”

Section: Introductionmentioning

confidence: 99%

Estimation of ocean contribution at the MODIS near‐infrared wavelengths along the east coast of the U.S.: Two case studies

Wang

Shi

2005

Geophysical Research Letters

235

144

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[1] Atmospheric correction for the ocean color products derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) uses two near-infrared (NIR) bands centered at 748 and 869 nm. Ocean is usually assumed to be black at these two NIR wavelengths. For Case-2 and high productive Case-1 waters, however, ocean could have significant contributions in the NIR, leading to significant under-estimation of the MODIS-derived waterleaving radiances. This is often the case in coastal regions. In this paper, measurements from the MODIS Terra at the short wave infrared (SWIR) wavelengths (1240 and 1640 nm) are used to evaluate the ocean contributions at wavelengths 748 and 869 nm. The ocean is black in coastal regions in these SWIR bands due to much stronger water absorption. Studies of two MODIS granules off the east coast of the U.S. show that the ocean could have reflectance values of $3.1% and $1.8% at the top of atmosphere (TOA) for bands 748 and 869 nm in the Outer Banks, while these values are $0.15% and $0.1% in the Chesapeake Bay region. Thus, for the turbid waters, it is important to accurately account for the ocean contributions in the NIR bands for the atmospheric correction of ocean color remote sensing. Citation: Wang, M., and W. Shi (2005), Estimation of ocean contribution at the MODIS near-infrared wavelengths along the east coast of the U.S.: Two case studies, Geophys. Res. Lett., 32, L13606,

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Section: Introductionmentioning

confidence: 99%

Estimation of ocean contribution at the MODIS near‐infrared wavelengths along the east coast of the U.S.: Two case studies

Wang

Shi

2005

Geophysical Research Letters

235

144

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“…The chlorophyll-a concentration is directly related to the surface reflectance ratio between different bands (Gordon, 1997). Though the MISR is not the ocean color sensor, its blue and green bands give information pertinent to the ocean color analysis.…”

Section: Chlorophyll-a Estimation From Misrmentioning

confidence: 99%

“…Microscopically, all these parameters are dependent on shape, size and composition of aerosols and well approximated. So far, several conventional algorithms were proposed in the EOS era (Gordon, 1997;Das, et al, 2002;Haltrin, 2002) to estimate aerosol optical thickness (AOT) and water-leaving radiance with certain accuracies using the data from satellite sensors with one viewing direction. In these algorithms, the I sun glitter radiance and the whitecapsi radiance are assumed to be constant in all the spectral regions and estimated with the!…”

Section: Introductionmentioning

confidence: 99%

Estimation of Chlorophyll-a Concentration From the Atmospheric Correction of Misr Data

Dash

Tanaka

Hachiya

et al. 2010

IJReSES

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Multi Angle Imaging Spectro Radiometer (MISR) has a capability to observe the ocean surface from different viewing directions. Attempts were made to estimate the ocean surface reflectance and chlorophyll-a concentration using MISR data. The aerosol optical thickness (AOT), available from the MISR archive is compared with the results simulated using the 6S radiation transfer code. It turns out that the AOT values agree with each other up to 85% in certain areas in case-1 waters. Substituting the archive values of AOT into the radiative transfer process, we obtain the surface reflectance. This surface reflectance, in turn, is employed together with the in-water algorithm, to obtain the chlorophyll concentration maps for three viewing directions (aft, nadir and forward). The pattern of obtained chlorophyll map is reasonable. It is estimated thai an error of about 35% is involved in the radiance calibration and AOT. Hence, with best possibility, the surface reflectance is quantified and the chlorophyll maps were generated. When it is compared with the nadir observation, the forward viewing camera overestimates and the aft viewing camera underestimates the chlorophyll-a concentration especially in case-1 waters-In case-2 waters, the chlorophyll-a concentration shows similar patterns for the three different viewing directions. Due to lack of in-situ data, absolute chlorophyll values were ignored but errors were quantified for (he surface reflectance and the aerosol optical thickness with the 6S simulated results.

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“…These are the normalized water-leaving radiance; that is, approximately the radiance that would exit the ocean in the absence of the atmosphere and with the sun at the zenith. 16 Another alternative to L w is the reflectance r w ; that is, L w normalized with respect to the extraterrestrial solar irradiance. 16 The important point to note is that whichever quantity is used it can be related to the presence of phytoplankton in the water, which will be discussed in the next subsection.…”

Section: Some Definitionsmentioning

confidence: 99%

Biological Oceanography by Remote Sensing

Srokosz

2000

Encyclopedia of Analytical Chemistry

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Biological oceanography may be studied from space using sensors on satellites that determine the color of the ocean. The presence of phytoplankton (microscopic algae) in the upper layers of the ocean changes the color of the water as seen from above. In simplified terms, this is due to the selective absorption of blue light by the phytoplankton pigments (primarily chlorophyll) which changes the appearance of the water from blue to green. These changes in color can be observed using a satellite‐borne spectroradiometer that measures the water‐leaving radiance in a number of bands in the visible part of the electromagnetic spectrum. The limitations of the technique are first, that only information on the phytoplankton in the upper layers of the ocean can be obtained (light does not penetrate very far into the ocean). Second, most of the signal measured by the satellite sensor originates in the atmosphere (due to the molecular and aerosol scattering of photons there), so careful correction for atmospheric effects is necessary if good ocean data are to be obtained. Of course, in the presence of clouds the sensor will not “see” the ocean surface at all, and no data will be obtained. Third, only one component of the ocean ecosystem, namely the phytoplankton, can be studied by this means. Despite these limitations, satellite observations of ocean color have given new insights into biological oceanography on a global scale that could not have been obtained by any other means of observation. Observations of ocean color have contributed to a better understanding of the biophysical interactions that determine the phytoplankton productivity, the seasonal and interannual variations of the phytoplankton biomass on global scales, and the role of phytoplankton in the climate system. They have also contributed to the improved modeling of biogeochemical processes in the ocean.

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Atmospheric correction of ocean color imagery in the Earth Observing System era

Cited by 614 publications

References 64 publications

Estimation of ocean contribution at the MODIS near‐infrared wavelengths along the east coast of the U.S.: Two case studies

Estimation of ocean contribution at the MODIS near‐infrared wavelengths along the east coast of the U.S.: Two case studies

Estimation of Chlorophyll-a Concentration From the Atmospheric Correction of Misr Data

Biological Oceanography by Remote Sensing

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