Partitioning total spectral absorption in phytoplankton and colored detrital material contributions

Oubelkheir, Kadija; Claustre, Hervé; Bricaud, Annick; Babin, Marcel

doi:10.4319/lom.2007.5.384

Cited by 30 publications

(11 citation statements)

References 25 publications

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“…On average, phytoplankton absorption contributes to 62 ± 5, 67 ± 5, and 59 ± 6 % of the particulate absorption measured at 440 nm in surface waters of LD stations A, B, and C, respectively. These proportions are consistent with previous studies performed in the Mediterranean Sea (Bricaud et al, 1998;Oubelkheir et al, 2007). These proportions significantly increase around the DCM to reach about 70 % ( Table 1).…”

Section: The Bio-optical Environment Of the Particulate Matter At Thesupporting

confidence: 82%

Characterization of the bio-optical anomaly and diurnal variability of particulate matter, as seen from scattering and backscattering coefficients, in ultra-oligotrophic eddies of the Mediterranean Sea

et al. 2011

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Abstract. The variability of inherent optical properties is investigated in the ultra-oligotrophic waters of the Mediterranean Sea sampled during the BOUM experiment performed during early summer 2008. Bio-optical relationships found for ultra-oligotrophic waters of the three anticyclonic gyres sampled significantly depart from the mean standard relationships provided for the global ocean, confirming the peculiar character of these Mediterranean waters. These optical anomalies are diversely related to the specific biological and environmental conditions occurring in the studied ecosystem. Specifically, the surface specific phytoplankton absorption coefficient exhibits values lower than those expected from the general relationships mainly in relation with a high contribution of relatively large sized phytoplankton. Conversely, the particulate backscattering coefficient, b bp , values are much higher than the mean standard values for a given chlorophyll-a concentration, TChl-a. This feature can presumably be related to the relevant influence of highly refractive submicrometer particles of Saharan origin in the surface layer of the water column. The present measurements Correspondence to: H. Loisel (hubert.loisel@univ-littoral.fr) also show that the Mediterranean Sea is greener than TChla alone indicates, as already stressed in previous studies. This color anomaly is partly explained by the estimated colored dissolved organic matter and submicrometer particles absorption coefficients, and to a greater extent by the high b bp /TChl-a values assuming that these particles backscatter light similarly in the green and blue parts of the visible spectrum. The diel variation of both the particulate matter attenuation and backscattering coefficients were also investigated specifically. Despite some differences in the timing and the magnitude of the daily oscillations found for these optical parameters, potential for the backscattering coefficient daily oscillation to be used, similarly to that for the attenuation coefficient, as a proxy for estimating carbon community production budget has been highlighted for the first time. This result is particularly relevant for present and future geostationary spatial ocean color missions.

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Section: The Bio-optical Environment Of the Particulate Matter At Thesupporting

confidence: 82%

Characterization of the bio-optical anomaly and diurnal variability of particulate matter, as seen from scattering and backscattering coefficients, in ultra-oligotrophic eddies of the Mediterranean Sea

et al. 2011

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“…This approach would, however, require a substantial investment in instrumentation and may not be feasible for long‐term deployments. Also, numerical and modeling methods exist to estimate phytoplankton absorption from total nonwater absorption (Oubelkheir et al, ; Zheng & Stramski, ; see also references therein).…”

Section: Resultsmentioning

confidence: 99%

Photoacclimation State of an Arctic Underice Phytoplankton Bloom

et al. 2019

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Recent reports on Arctic underice phytoplankton blooms have directed attention to primary production below the sea ice cover. Such underice blooms cannot be detected from space; thus, methods for autonomous underice measurements are critically needed to extend observations beyond ship‐based surveys. One central aspect of the ecology of these blooms is whether they were advected from open‐water areas or were able to develop below the ice cover under typically low light conditions. The photoacclimation state of the bloom can provide clues about the growth conditions and therefore its origin. Here we investigate the photoacclimation state of a Phaeocystis pouchetii‐dominated underice bloom in the Arctic Ocean using ratios of photoprotective carotenoids (PPC) to photosynthetic carotenoids (PSC) and chlorophyll a. The pigment proxies indicate local growth under the ice pack. Furthermore, a method using in situ light absorption measurements to estimate the PPC:PSC ratio was in agreement with the pigment data. The slope of in situ phytoplankton absorption between 488 and 532 nm, affected by both PPC and PSC, had a significant linear relationship to the PPC:PSC ratio, indicating that prediction of photoacclimation state can be obtained from absorption profiles. We also review, with regard to the pigment function, different ways of grouping pigments into PPC or PSC applied in previous studies. Although more validation data sets are needed to assess the impact of pigment packaging on the relationship between PPC:PSC and absorption measurement slopes, our study shows the potential for using in situ absorption measurements to collect information about phytoplankton physiology below sea ice.

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“…The non-water absorption coefficients, a(λ) and a w (λ),were partitioned into phytoplankton and CDM contributions, using a method derived from that proposed by Bricaud and Stramski (1990) for partitioning particulate absorption coefficients into their algal and nonalgal components. A modified method was already developed to partition total (i.e., dissolved and particulate) absorption coefficients, as measured with an ac-9 (Wetlabs) absorption meter, into their algal and nonalgal contributions (Oubelkheir and Bricaud 2003;K. Oubelkheir, H. Claustre, A. Bricaud, and M. Babin, unpublished data).…”

Section: Materials and Proceduresmentioning

confidence: 99%

“…Some inversion methods were also proposed to partition total absorption spectra, as measured in situ, into those of phytoplankton, detritus, and CDOM, or CDM (Chang and Dickey 1999, Gallegos and Neale 2002, Oubelkheir and Bricaud 2003, Schofield et al 2004). These methods have generally been applied with some success to in situ measurements performed with absorption meters such as the WET Labs ac-9.…”

Section: Introductionmentioning

confidence: 99%

“…Then we report the results of 2 inversion methods aimed at retrieving simultaneously, from total absorption coefficients, the amplitude and spectral shape of light absorption by CDM and a cell size parameter for phytoplankton. The first approach is based on the work by Oubelkheir and Bricaud (2003) and K. Oubelkheir, H. Claustre, A. Bricaud, and M. Babin (unpublished data), who adapted the method proposed by Bricaud and Stramski (1990) for the decomposition of particulate absorption, to make it applicable to total absorption measured with an in situ absorption meter. In the present work, the method was modified again for retrieving CDM and phytoplankton contributions from total absorption at SeaWiFS wavelengths.…”

Section: Introductionmentioning

confidence: 99%

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Retrievals of a size parameter for phytoplankton and spectral light absorption by colored detrital matter from water-leaving radiances at SeaWiFS channels in a continental shelf region off Brazil

Ciotti

Bricaud

2006

Limnol. Oceanogr. Methods

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193

181

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Many efforts are currently oriented toward extracting more information from ocean color than the chlorophyll a concentration. Among biological parameters potentially accessible from space, estimates of phytoplankton cell size and light absorption by colored detrital matter (CDM) would lead to an indirect assessment of major components of the organic carbon pool in the ocean, which would benefit oceanic carbon budget models. We present here 2 procedures to retrieve simultaneously from ocean color measurements in a limited number of bands, magnitudes, and spectral shapes for both light absorption by CDM and phytoplankton, along with a size parameter for phyto-plankton. The performance of the 2 procedures was evaluated using different data sets that correspond to increasing uncertainties: (1) measured absorption coefficients of phytoplankton, particulate detritus, and colored dissolved organic matter (CDOM) and measured chlorophyll a concentrations and (2) SeaWiFS upwelling radiance measurements and chlorophyll a concentrations estimated from global algorithms. In situ data were acquired during 3 cruises, differing by their relative proportions in CDM and phytoplankton, over a continental shelf off Brazil. No local information was introduced in either procedure, to make them more generally applicable. Over the study area, the absorption coefficient of CDM at 443 nm was retrieved from SeaWiFS radiances with a relative root mean square error (RMSE) of 33%, and phytoplankton light absorption coefficients in SeaWiFS bands (from 412 to 510 nm) were retrieved with RMSEs between 28% and 33%. These results are comparable to or better than those obtained by 3 published models. In addition, a size parameter of phytoplankton and the spectral slope of CDM absorption were retrieved with RMSEs of 17% and 22%, respectively. If these methods are applied at a regional scale, the performances could be substantially improved by locally tuning some empirical relationships. DEPROAS program was funded by PRONEX-CNPq, and bio-optical measurements were funded by FAPESP (2001/00125-0). SeaWiFS data, as well as the data processing software, were provided by DAAC.

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Partitioning total spectral absorption in phytoplankton and colored detrital material contributions

Cited by 30 publications

References 25 publications

Characterization of the bio-optical anomaly and diurnal variability of particulate matter, as seen from scattering and backscattering coefficients, in ultra-oligotrophic eddies of the Mediterranean Sea

Characterization of the bio-optical anomaly and diurnal variability of particulate matter, as seen from scattering and backscattering coefficients, in ultra-oligotrophic eddies of the Mediterranean Sea

Photoacclimation State of an Arctic Underice Phytoplankton Bloom

Retrievals of a size parameter for phytoplankton and spectral light absorption by colored detrital matter from water-leaving radiances at SeaWiFS channels in a continental shelf region off Brazil

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