scholarly journals Dissolved inorganic carbon budgets in the eastern subpolar North Atlantic in the 2000s from in situ data

2015 ◽  
Vol 42 (22) ◽  
pp. 9853-9861 ◽  
Author(s):  
Patricia Zunino ◽  
Pascale Lherminier ◽  
Herlé Mercier ◽  
Xose A. Padín ◽  
Aida F. Ríos ◽  
...  
Keyword(s):  
North Atlantic ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Carbon Budgets ◽  
In Situ Data

Evaluation of reagentless pH modification for in situ ocean analysis: determination of dissolved inorganic carbon using mass spectrometry

2013 ◽  
Vol 27 (5) ◽  
pp. 635-642 ◽  
Author(s):  
Andres M. Cardenas-Valencia ◽  
Lori R. Adornato ◽  
Ryan J. Bell ◽  
Robert H. Byrne ◽  
R. Timothy Short
Keyword(s):  
Mass Spectrometry ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Analysis Determination

In Situ Sensor Technology for Simultaneous Spectrophotometric Measurements of Seawater Total Dissolved Inorganic Carbon and pH

2015 ◽  
Vol 49 (7) ◽  
pp. 4441-4449 ◽  
Author(s):  
Zhaohui Aleck Wang ◽  
Frederick N. Sonnichsen ◽  
Albert M. Bradley ◽  
Katherine A. Hoering ◽  
Thomas M. Lanagan ◽  
...  
Keyword(s):  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Sensor Technology ◽  
Total Dissolved Inorganic Carbon ◽  
In Situ Sensor

Controls on in situ oxygen and dissolved inorganic carbon dynamics in peats of a temperate fen

2012 ◽  
Vol 117 (G2) ◽  
pp. n/a-n/a ◽  
Author(s):  
Cristian Estop-Aragonés ◽  
Klaus-Holger Knorr ◽  
Christian Blodau
Keyword(s):  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Carbon Dynamics

scholarly journals The seasonal cycle of δ<sup>13</sup>C<sub>DIC</sub> in the North Atlantic Subpolar Gyre

2013 ◽  
Vol 10 (8) ◽  
pp. 14515-14537
Author(s):  
V. Racapé ◽  
N. Metzl ◽  
C. Pierre ◽  
G. Reverdin ◽  
P. D. Quay ◽  
...  
Keyword(s):  
North Atlantic ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Subpolar Gyre ◽  
The North ◽  
Winter Convection ◽  
North Atlantic Subpolar Gyre ◽  
The North Atlantic ◽  
First Time ◽  
Strong Linear Relationship

Abstract. This study introduces for the first time the δ13CDIC seasonality in the North Atlantic Subpolar Gyre (NASPG) using δ13CDIC data obtained between 2005 and 2012 with Dissolved Inorganic Carbon (DIC) and nutrient observations. On the seasonal scale, the NASPG is characterized by higher δ13CDIC values during summer than during winter with seasonal amplitude of 0.77‰. This is attributed to biological activity in summer and to deep remineralization process during winter convection. During all seasons, we observed a strong linear relationship between δ13CDIC and DIC. Results also revealed a negative anomaly for DIC and nutrients in August 2010 that could be explained by a coccolithophore bloom associated to a warming up to +2 °C. Winter data also showed a large decrease in δ13CDIC associated with an increase in DIC between 2006 and 2011–2012 but with observed time rates (−0.04‰ yr−1and +1.7 μmol kg−1 yr−1) much larger than the expected anthropogenic signal.

scholarly journals Vertically migrating phytoplankton drive seasonal formation of subsurface negative preformed nitrate anomalies in the subtropical North Pacific and North Atlantic

2018 ◽  
Author(s):  
Robert T. Letscher ◽  
Tracy A. Villareal
Keyword(s):  
Organic Matter ◽  
Mixed Layer ◽  
North Atlantic ◽  
North Pacific ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Euphotic Zone ◽  
The North ◽  
Station Aloha ◽  
Biological Nitrogen

Abstract. Summertime drawdown of dissolved inorganic carbon in the absence of measurable nutrients from the mixed layer and subsurface negative preformed nitrate (preNO3) anomalies observed for the ocean's subtropical gyres are two biogeochemical phenomena that have thus far eluded complete description. Many processes are thought to contribute including biological nitrogen fixation, lateral nutrient transport, carbon overconsumption or non-Redfield C : N : P organic matter cycling, heterotrophic nutrient uptake, and the actions of vertically migrating phytoplankton. Here we investigate the seasonal formation rates and potential contributing mechanisms for negative preformed nitrate anomalies (oxygen consumption without stoichiometric nitrate release) in the subsurface and positive preformed nitrate anomalies (oxygen production without stoichiometric nitrate drawdown) in the euphotic zone at the subtropical ocean time series stations ALOHA in the North Pacific and BATS in the North Atlantic. Non-Redfield −O2 : N stoichiometry for dissolved organic matter (DOM) remineralization is found to account for up to ~ 15 mmol N m−2 yr−1 of negative preNO3 anomaly formation at both stations. Residual negative preNO3 anomalies in excess of that which can be accounted for by non-Redfield DOM cycling are found to accumulate at a rate of ~ 32–46 mmol N m−2 yr−1 at station ALOHA and ~ 46–87 mmol N m−2 yr−1 at the BATS station. These negative anomaly formation rates are in approximate balance with positive preNO3 anomaly formation rates from the euphotic zone located immediately above the nutricline in the water column. Cycling of transparent exopolymer particles (TEP) and heterotrophic nitrate uptake can contribute to the formation of these preNO3 anomalies, however a significant fraction, estimated at ~ 50–95 %, is unexplained by the sum of these processes. Vertically migrating phytoplankton possess the necessary nutrient acquisition strategy and biogeochemical signature to quantitatively explain both the residual negative and positive preNO3 anomalies as well as the mixed layer dissolved inorganic carbon drawdown at stations ALOHA and BATS. TEP production by the model Rhizosolenia mat system could provide accelerated vertical transport of TEP as well as link the three processes together. Phytoplankton vertical migrators, although rare and easily overlooked, may play a large role in subtropical ocean nutrient cycling and the biological pump.

scholarly journals Impact of hydrographic data assimilation on the Atlantic meridional overturning circulation

2009 ◽  
Vol 6 (3) ◽  
pp. 2667-2715 ◽  
Author(s):  
G. C. Smith ◽  
K. Haines ◽  
T. Kanzow ◽  
S. Cunningham
Keyword(s):  
Data Assimilation ◽  
North Atlantic ◽  
Atlantic Meridional Overturning Circulation ◽  
Meridional Overturning Circulation ◽  
Density Gradients ◽  
Overturning Circulation ◽  
In Situ Data ◽  
Meridional Overturning ◽  
Gyre Circulation

Abstract. The poleward ocean heat transports in the North Atlantic controlled by the Atlantic Meridional Overturning Circulation (AMOC), play a key role in regional climate. If the AMOC can be initialized in numerical models through ocean assimilation this may help improve the predictability of North Atlantic climate variability on timescales out to a few years. Here we make an initial step toward the development of an ocean assimilation system that can determine the AMOC to support climate predictions. A detailed comparison is presented of 1° and 1/4° resolution global model simulations with and without sequential data assimilation to the observations and transport estimates from the RAPID/MOCHA mooring array across 26.5° N in the Atlantic. Comparisons of modelled water properties with the observations from the merged RAPID boundary arrays demonstrate the ability of in situ data assimilation to accurately constrain the east-west density gradient between these mooring arrays. However, the presence of an unconstrained "western boundary wedge" between Abaco Island and the RAPID mooring site WB2 (16 km offshore) leads to the intensification of an erroneous southwards flow in this region when in situ data are assimilated. The result is an overly intense southward upper mid-ocean transport (0–1100 m) as compared to the estimates derived from the RAPID array. Correction of upper layer zonal density gradients is found to compensate mostly for a weak subtropical gyre circulation in the free model run (i.e. with no assimilation). Despite the important changes to the density structure and transports in the upper layer imposed by the assimilation, very little change is found in the amplitude and sub-seasonal variability of the AMOC. This shows that assimilation of upper layer density information projects mainly on the gyre circulation with little effect on the AMOC at 26° N due to the absence of corrections to density gradients below 2000 m (the maximum depth of Argo). The sensitivity to initial conditions was explored through two additional experiments using a climatological initial condition. These experiments showed that the weak bias in gyre intensity in the control simulation (without data assimilation) develops over the period of about 6 months, but does so independently from the overturning, with no change to the AMOC. However, differences in the properties and volume of North Atlantic Deep Water (NADW) persisted throughout the 3 year simulations resulting in a difference of 3 Sv in AMOC intensity. The persistence of these dense water anomalies and their influence on the AMOC is promising for the development of decadal forecasting capabilities. The results suggest that the deeper waters must be accurately reproduced in order to constrain the AMOC.

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