Related Experiment Video
Updated: Jan 21, 2026
10:28
Investigating the Relationship between Sea Surface Chlorophyll and Major Features of the South China Sea with Satellite Information
Published on: June 13, 2020
6.3K
CHLOROPHYLL ALGORITHMS FOR OCEAN COLOR SENSORS - OC4, OC5 & OC6
John E O'Reilly1, P Jeremy Werdell2
1Retired, NOAA National Marine Fisheries Service, Narragansett, Rhode Island 02882, USA.
Remote Sensing of Environment
|August 6, 2019
Summary
New ocean color algorithms enhance chlorophyll estimation by incorporating the 412 nm band, improving data consistency across missions. This advancement aids in merging satellite data for a more comprehensive view of global ocean chlorophyll levels.
Area of Science:
- Oceanography
- Remote Sensing
- Biogeochemistry
Background:
- Consistent chlorophyll algorithms are crucial for merging data from overlapping ocean color missions, extending time series, and incorporating new satellite data (e.g., PACE, OLCI).
- The violet band (412 nm) has been underutilized in empirical algorithms despite its potential for estimating chlorophyll, especially in oligotrophic waters where it represents the brightest spectral band.
Purpose of the Study:
- To develop highly consistent and comparable empirical ocean color (OC) algorithms for merging satellite data and extending time series.
- To explore the utility of the 412 nm band in estimating chlorophyll concentrations and to develop new algorithms (OC5, OC6) incorporating this band.
- To establish a bio-optically based index for defining and quantifying trophic status (oligotrophic, mesotrophic, eutrophic) in the global ocean.
Main Methods:
- Developed 65 empirical OC maximum band ratio (MBR) algorithms for 25 satellite instruments using a large, globally representative database of coincident in situ chlorophyll a and remote sensing reflectances.
- Validated algorithm performance using SeaWiFS and MODIS-Aqua satellite-to-in situ match-ups.
- Introduced OC5 and OC6 algorithm families incorporating the 412 nm band to maximize dynamic range in oligotrophic areas.
- Developed a reproducible trophic status index based on the MBR's brightest band frequency and SeaWiFS mission data.
Main Results:
- Achieved excellent internal consistency across OC 'Version -7' algorithms, with median regression slopes and R2 values of 0.985 and 0.859, respectively.
- Demonstrated equivalent or superior performance of new algorithms compared to heritage chlorophyll algorithms in SeaWiFS and MODIS-Aqua match-ups.
- Quantified global ocean trophic status: oligotrophic (~24%), mesotrophic (~67%), and eutrophic (~9%) waters based on the new index and 40-year chlorophyll data.
Conclusions:
- The developed OC algorithms provide high consistency and comparability, supporting the merging of multi-mission ocean color data.
- Incorporating the 412 nm band enhances chlorophyll estimation, particularly in oligotrophic regions, and improves the dynamic range of MBR algorithms.
- The new bio-optically based trophic status index offers a quantitative and reproducible method for classifying ocean conditions globally.
Related Concept Videos
03:02Colors and Magnetism
14.0K
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
14.0K
01:24Color Vision
1.4K
Color perception begins in the retina, the light-sensitive layer at the back of the eye. Two main theories explain how colors are seen: the trichromatic theory and the opponent-process theory. The trichromatic theory, proposed by Thomas Young in 1802 and extended by Hermann von Helmholtz in 1852, suggests that color vision is based on three types of cone receptors in the retina. These cones are sensitive to different but overlapping ranges of wavelengths corresponding to red, blue, and green.
1.4K
01:12Trial and Error and Algorithm
399
A problem-solving strategy is a plan of action used to find a solution. Different strategies have distinct action plans. Trial and error involves trying different solutions until one works. For instance, to fix a broken printer, you might check ink levels, ensure the paper tray isn't jammed, and verify the printer's connection to your laptop. This method can be time-consuming but is commonly used. Thomas Edison, for example, used trial and error to find a suitable filament for the light...
399
01:14Changes in Skin Color: Clinical Perspectives
3.3K
The first thing a clinician sees is the skin, so the examination of the skin should be part of any thorough physical examination. Most skin disorders are relatively benign, but a few, including melanomas, can be fatal if untreated. A couple of the more noticeable disorders, albinism and vitiligo, affect the appearance of the skin and its accessory organs.
Albinism
Albinism is a genetic disorder that affects (completely or partially) the coloring of skin, hair, and eyes. The defect is primarily...
Albinism
Albinism is a genetic disorder that affects (completely or partially) the coloring of skin, hair, and eyes. The defect is primarily...
3.3K
01:29Mechanistic Models: Compartment Models in Algorithms for Numerical Problem Solving
300
Mechanistic models play a crucial role in algorithms for numerical problem-solving, particularly in nonlinear mixed effects modeling (NMEM). These models aim to minimize specific objective functions by evaluating various parameter estimates, leading to the development of systematic algorithms. In some cases, linearization techniques approximate the model using linear equations.
In individual population analyses, different algorithms are employed, such as Cauchy's method, which uses a...
In individual population analyses, different algorithms are employed, such as Cauchy's method, which uses a...
300
01:30Assessment of Airway, Skin Color, and Use of Accessory Muscles
1.6K
A thorough assessment of respiratory health is paramount in clinical settings to identify and manage respiratory distress and ensure adequate oxygenation. This article elaborates on the critical aspects of respiratory evaluation, including airway assessment, skin color examination, and the observation of accessory muscle use, which are integral to effectively diagnosing and managing patients with respiratory conditions.
Introduction
The initial evaluation of a patient's respiratory system...
Introduction
The initial evaluation of a patient's respiratory system...
1.6K