The Atlantic Meridional Transect: overview and synthesis of data

Aiken, J. David; Rees, N.W.; Hooker, SB; Holligan, P. M.; Bale, A.J.; Robins, D. A.; Moore, GF; Harris, RP; Pilgrim, DA

doi:10.1016/s0079-6611(00)00005-7

Cited by 103 publications

(62 citation statements)

References 33 publications

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“…Although observed nitrate concentrations can be as high as 8 mol L Ϫ1 at depth, a nitrate concentration of 2 mol L Ϫ1 at 150 m was used in the model to take into account the strong stratification at these latitudes, as in Taylor et al (1997). mg Chl a m Ϫ3 , consistent with the weak seasonal cycle of surface irradiance used in this simulation. The modeled Chl a profile was within the range observed during Atlantic Meridional Transect (AMT; Aiken et al 2000). The subsurface Chl a maximum occurred at a depth of 75 m in the model, in agreement with the October 1998 data (Fig.…”

Section: Resultssupporting

confidence: 85%

Modeling carbon to nitrogen and carbon to chlorophyll a ratios in the ocean at low latitudes: Evaluation of the role of physiological plasticity

Lefèvre

Taylor

Gilbert

et al. 2003

Limnology & Oceanography

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Simulation modeling provides a means for testing the limits of our quantitative understanding of the factors that control phytoplankton biomass, growth rate, and primary productivity in the sea. We simulated the annual cycles of chlorophyll a (Chl a) concentration, primary productivity, nitrogen export, phytoplankton carbon to nitrogen (C : N) and carbon to Chl a ratios (C : Chl a) using a physiological model of phytoplankton carbon, nitrogen, and Chl a dynamics. The model was embedded within a one-dimensional physical model of vertical exchanges that included simple mortality and recycling terms. A sensitivity analysis allowed evaluation of the relative effects of changes in phytoplankton physiology, physical forcing, mortality, and nutrient cycling on Chl a distributions and phytoplankton C : N. Critical to the success of the model was the treatment of mortality, which included seasonal (temperature) and depth-related components, and the treatment of recycling efficiency, which was considered to be a function of the inorganic nitrogen concentration. The subtropical simulation compared favorably with data obtained at the Bermuda Atlantic Time-series Study (BATS) station. Our results illustrate the utility of physiological data in validation of biogeochemical models. In particular, model predictions of phytoplankton C : Chl a, which ranged from 30 to 170 g C (g Chl a)Ϫ1 , compared well with direct estimates based on 14 C labeling of Chl a. However, predictions of phytoplankton C : N, which ranged from ϳ5-9 g C (g N) Ϫ1 , could not be verified because of lack of data. This range of C : N suggests a slight limitation of phytoplankton growth rates by nutrients in surface waters.At the heart of pelagic biogeochemical models are the phytoplankton because they are responsible for carbon dioxide fixation. In addition, the extensive and growing database of chlorophyll a (Chl a) measurements provides the major reality check on the performance of pelagic biogeochemical models. Despite the explicit treatment of phytoplankton growth in these models, growth rates generated by the models typically do not agree with observations. Observed phytoplankton growth rates () in the mixed layer of subtropical gyres typically equal 0.6-0.7 d Ϫ1 (Lessard and Murrell 1998;Claustre et al. 1999;Stelfox-Widdicombe et al. 2000), whereas models typically return values of 0.1-0.2 d Ϫ1 (Fasham et al. 1990;Doney et al. 1996). Observations indicate that the phytoplankton relative growth rate (/ m ) is not severely nutrient-limited in subtropical and tropical

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Section: Resultssupporting

confidence: 85%

Modeling carbon to nitrogen and carbon to chlorophyll a ratios in the ocean at low latitudes: Evaluation of the role of physiological plasticity

Lefèvre

Taylor

Gilbert

et al. 2003

Limnology & Oceanography

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“…2). The main Atlantic water masses were identified according to commonly used classification schemes Alvarez et al, 2004;Aiken et al, 2000;Joyce et al, 2001;Poole and Tomczak, 1999).…”

Section: Hydrographymentioning

confidence: 99%

“…Additional water masses of the southern hemisphere that penetrate into the North Atlantic are the South Atlantic Central Water (SACW) and the Antarctic Bottom Water (AABW). SACW flows northwards, and mixes with the North Atlantic Central Water (NACW) at approximately 15 • N in the western and 20 • N in the eastern basin (Poole and Tomczak, 1999;Aiken et al, 2000).…”

Section: Hydrographymentioning

confidence: 99%

Nitrous oxide in the North Atlantic Ocean

et al. 2006

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“…The Atlantic Meridional Transect programme was initiated to investigate basin-scale variability in physical and biological processes in the Atlantic Ocean (Aiken et al, 2000;Robinson et al, 2006) and research cruises have been undertaken since 1995, mainly between the UK (50°N) and the Falkland Isles (50°S) (Aiken et al, 2009). Most of the cruise tracks have predominated across oligotrophic waters of the northern and southern gyres where TChla (total chlorophyll a) is o0.25 mg m À 3 and flow cytometric analysis demonstrated the dominance of picoprokaryotes (Prochlorococcus and Synechococcus spp.)…”

Section: Introductionmentioning

confidence: 99%