Ocean colour and an empirical chlorophyll retrieval
Ocean-colour band-ratio models estimate near-surface chlorophyll-a from water-leaving remote-sensing reflectances.
Key knowledge
Ocean-colour band-ratio models estimate near-surface chlorophyll-a from water-leaving remote-sensing reflectances. In the OC family, X=log₁₀(Rrs_blue/Rrs_green) uses a specified maximum blue band and a green band, and log₁₀(CHL/(1mg m⁻³))=Σ_(j=0)^4a_jX^j. Coefficients and bands are empirically calibrated for a sensor/model version; this is a retrieval relationship rather than a direct count of phytoplankton.
Values and equations
X=log₁₀(Rrs_blue/Rrs_green); log₁₀(CHL/(1mg m⁻³))=Σ_(j=0)^4a_jX^j
- Rrs_blue,Rrs_green
- declared maximum-blue/green remote-sensing reflectances sr⁻¹
- X,a_j
- log ratio and fitted sensor/version coefficients 1
- CHL
- estimated near-surface chlorophyll-a concentration mg m⁻³
Conditions and scope
- Positive compatible reflectance ratio, atmosphere-corrected water-leaving signal, specified sensor bands, calibrated coefficients and validation domain. Rrs has units sr⁻¹; the ratio is dimensionless and CHL is a near-surface concentration estimate.
- Non-algal particles/coloured dissolved matter, adjacency, atmospheric errors and unusual bio-optical conditions can break training relationships. The product does not directly measure depth-integrated biomass, productivity or all biological diversity; historical polynomial coefficients are not a present operational guarantee.
Sources · 2
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
- Chlorophyll algorithms for ocean color sensors, Introduction limitations and§2.1 equations1–3, printed34–35John E. O'Reilly and P. Jeremy Werdell (2019), author research article hosted by NASA NTRSReference guide · PDF
- MODIS Chlorophyll-a Concentration, empirical near-surface band-ratio overviewNASA Goddard MODIS Science TeamReference guide
Evidence and review
Read actual primary article introduction optical constituent/atmospheric limits and§2.1 displayed polynomial, log band ratio and sensor/maximum-band definitions, plus actual MODIS empirical near-surface overview. Retained the family form with version-specific parameters, excluding obsolete launch/current-default claims, exact fit-performance numbers and treating current algorithm web availability as verified. The OceanColor ATBD URL could not be opened and is not credited as inspected.
2026-10-10 · Independent AI editorial review: All73 exact supplement compact statements, conditions, displayed equations and247 origin semantic links read; all109 combined original36+supplement73 author-source rows, exact locators, hypotheses, exclusions and disclosed derivations assessed. Original36 exact scientific content is independently approved in the linked receipt. All18 inherited Earth compact references and shared Math/Physics/Measurement methods were considered in the full practical Earth inventory. Targeted actual primary sections listed below; not every source body/proof or every possible university elective independently reread. AI editorial reference review, not human certification, full-degree proficiency, new experimental validation or a claim of whole combined Earth-and-Cosmos approval. Receipt: earth-completion-independent-content-inventory-review.1.
Entry details
Permanent link to this entry ↗- Record identity
- uni-earth-ocean-colour-chlorophyll
- Revision
- core.1
- Structured reference record
- University core expansion