Surface chlorophyll as an index of the depth, chlorophyll content, and primary productivity of the euphotic layer1
About: This article is published in Limnology and Oceanography.The article was published on 1970-05-01 and is currently open access. It has received 79 citations till now. The article focuses on the topics: Chlorophyll.
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TL;DR: In this paper, a pigment-dependent optical model is developed to predict the propagation of visible radiant energy within the ocean or the backscattered radiation from the upper layer to be predicted as a function of the local phytoplanktonic content.
Abstract: The aim of the present study is to review and tentatively to interpret the optical behavior of oceanic case I waters, those waters for which phytoplankton and their derivative play a predominant role in determining their optical properties. Chlorophyll-like pigment concentration is used as the index to quantify the algal material (living and detrital), and statistical relationships between this index and the depth of the euphotic layer, the spectral values of the attenuation coefficient for downwelling irradiance, or the scattering coefficient are investigated. On the basis of these statistical relationships a pigment-dependent optical model is developed. It allows the propagation of the visible radiant energy within the ocean or the backscattered radiation from the upper layer to be predicted as a function of the local phytoplanktonic content. Other geophysical or geochemical applications are derived which concern the heating rate due to penetrating visible radiations or the rate of energy storage due to photosynthesis. The nonlinear trends observed in the algal biomass-attenuation relationships are analyzed by (1) considering the rather regular change of the living-to-detrital organic carbon ratio which seems to occur in oceanic waters ranging from oligotrophic to eutrophic, and (2) accounting for the respective contributions of absorption (by pigmented cells) and of scattering (by all kind of particulates) in the attenuation process of radiant energy.
1,385 citations
TL;DR: In this paper, the vertical profiles of surface chlorophyllous pigment (Chl a + Pheo a) determined only in oceanic Case 1 waters have been statistically analyzed.
Abstract: Maps of surface chlorophyllous pigment (Chl a + Pheo a) are currently produced from ocean color sensors. Transforming such maps into maps of primary production can be reliably done only by using light-production models in conjuction with additional information about the column-integrated pigment content and its vertical distribution. As a preliminary effort in this direction. $\ticksim 4,000$ vertical profiles pigment (Chl a + Pheo a) determined only in oceanic Case 1 waters have been statistically analyzed. They were scaled according to dimensionless depths (actual depth divided by the depth of the euphotic layer, $Z_e$) and expressed as dimensionless concentrations (actual concentration divided by the mean concentration within the euphotic layer). The depth $Z_e$ generally unknown, was computed with a previously develop bio-optical model. Highly sifnificant relationships were found allowing $\langle C \rangle_tot$, the pigment content of the euphotic layer, to be inferred from the surface concentration, $\bar C_pd$, observed within the layer of one penetration depth. According to their $\bar C_pd$ values (ranging from $0.01 to > 10 mg m^-3$), we categorized the profiles into seven trophic situations and computed a mean vertical profile for each. Between a quasi-uniform profile in eutrophic waters and a profile with a strong deep maximum in oligotrophic waters, the shape evolves rather regularly. The wellmixed cold waters, essentially in the Antarctic zone, have been separately examined. On average, their profiles are featureless, without deep maxima, whatever their trophic state. Averaged values their profiles are featureless, without deep maxima, whatever their trophic state. Averaged values their profiles are featureless, without deep maxima, whatever their trophic state. Averaged values of $ρ$, the ratio of Chl a tp (Chl a + Pheo a), have also been obtained for each trophic category. The energy stored by photosynthesizing algae, once normalized with respect to the integrated chlorophyll biomass $\langle C \rangle _tot $ is proportional to the available photosythetic energy at the surface via a parameter $ψ∗$ which is the cross-section for photosynthesis per unit of areal chlorophyll. By tanking advantage of the relative stability of $ψ∗.$ we can compute primary production from ocean color data acquired from space. For such a computation, inputs are the irradiance field at the ocean surface, the "surface" pigment from which $\langle C \rangle _tot$ can be derived, the mean $ρ value pertinent to the trophic situation as depicted by the $\bar C_pd or $\langle C \rangle _tot$ values, and the cross-section $ψ∗$. Instead of a contant $ψ∗.$ value, the mean profiles can be used; they allow the climatological field of the $ψ∗.$ parameter to be adjusted through the parallel use of a spectral light-production model.
685 citations
TL;DR: The diffilse attenuation cocfficicnt for irradiance, KT, is a physical measure of the bio-optical state of ocean waters, which can be remotely sensed by spacecraft sensors.
Abstract: The diffilse attenuation cocfficicnt for irradiance, KT, is a physical measure of the bio-optical state of ocean waters. From an analysis of irradiance, KT, and pigment concentration, the specific attenuation due to chlorophyll-like pigments is found to bc 0.016 +- 0.003 Irn-’ (mg pigment m-“)-‘I. The bio-optical state of ocean waters can be remotely sensed by spacecraft sensors. KT is readily measured at sea and is highly correlated with and dependent on the chlorophyll-like pigment concentration, C K. This pigment concentration and KT provide a measure of the fraction of radiant energy attenuated by phytoplankton. This fraction, in turn, is closely related to the production equations formulated by Bannister and can be directly incorporated into a general theory of phytoplankton dynamics. CK may also be used as an index of primary prodlrctivity. The determination of the bio-optical state of ocean waters by surface vessel provides direct information concerning the productivity of these waters; to the extent that the bio-optical state can be determined by satellite, it may be possible to examinc important paramctcrs of the marine ecosystem rapidly and repeatedly. The rcmotc sensing from spacecraft of the upwelling spectral radiant energy from the ocean’s surface makes it possihlc to determine marine pigment conccntrations due to phytoplankton. This, in turn, suggests the potential for obtaining rapid worldwide assessments of primary productivity over time scales required to link this productivity to commercially important fisheries. Continuous worldwide data on ocean productivity would assist synoptic ecological studies of ocean regions of special interest, provide othcrwise unattainable data for the dynamic modcling of phytoplankton, and allow for the continuous monitoring of variations in productivity. If these expectations for remote sensing are to bc fully realized, technical methods for detecting and analyzing the upwelling radiant energy must bc perfected and relationships between ocean optical properties and the biological parameters affecting thcsc optical properties must bc quantitatively investigated. Possible techniques for detecting
336 citations
01 Oct 1995
TL;DR: In this article, a bio-geochemical classification of the N. Atlantic Basin is presented according to which the basin is first divided into four primary algal domains: Polar, West-Wind, Trades and Coastal.
Abstract: A bio-geochemical classification of the N. Atlantic Basin is presented according to which the basin is first divided into four primary algal domains: Polar, West-Wind, Trades and Coastal. These are in turn sub-divided into smaller provinces. The classification is based on differences in the physical environment which are likely to influence regional algal dynamics. The seasonally-differentiated parameters of the photosynthesis-light curve (P-I curve) and parameters that define the vertical structure in chlorophyll profile are then established for each province, based on an analysis of an archive of over 6000 chlorophyll profiles, and over 1800 P-I curves. These are then combined with satellite-derived chlorophyll data for the N. Atlantic, and information on cloud cover, to compute primary production at the annual scale. using a model that computes spectral transmission of light underwater, and spectral, photosynthetic response of phytoplankton to available light. The results are compared with earlier, satellite-derived, estimates of basin-scale primary production.
275 citations
TL;DR: In this paper, the spectral attenuation coefficient due to phytoplankton is shown to be consistent with laboratory measurements of the diffuse absorption coefficient of various lot cultures of phyto-worms, and the relationship between spectral diffuse attenuation coefficients for irradiance and the chlorophyll-like pigment concentration has been found with spectral irradiance data from diverse types of ocean waters.
Abstract: A technique has been developed that leads to an optical classification of natural waters in terms of the dissolved and suspended biogenous material present. As a first approximation, this classification has been made in terms of the total chlorophyll-like pigment concentration.
A relationship between the spectral diffuse attenuation coefficient for irradiance and the chlorophyll-like pigment concentration has been found with spectral irradiance data from diverse types of ocean waters. The specific spectral attenuation coefficient due to phytoplankton is shown to be consistent with laboratory measurements of the diffuse absorption coefficient of various lot cultures of phytoplankton.
271 citations