Carbon dioxide, hydrographic, and chemical data obtained during the R/V Meteor Cruise 22/5 in the South Atlantic Ocean (WOCE Section A10, December 1992--January 1993)

This documentation discusses the procedures and methods used to measure total carbon dioxide (TCO{sub 2}), total alkalinity at Hydrographic stations as well as the underway partial pressure of CO{sub 2} (pCO{sub 2}) during the R/V Meteor Cruise M22/5 in the South Atlantic Ocean (Section A10). Conducted as part of the World Ocean Circulation Experiment (WOCE), the cruise began in Rio de Janeiro on 27 December 1992, and ended after 36 days at sea in Capetown, South Africa on 31 January 1993. Instructions for accessing the data are provided. TCO{sub 2} was measured using tow automated sample processors for extracting CO{sub 2} from seawater samples which were coupled to a Coulometer for detection of the extracted CO{sub 2}. The overall precision and accuracy of the analyses was {+-} 1.9 {micro}mol/kg. Samples collected for total alkalinity were measured by potentiometric titration; precision was {+-} 2.0 {micro}mol/kg. Underway pCO{sub 2} was measured by Infra Red (IR) Photometry; precision was {+-} 2.0 {micro}atm. From these cruises the large-scale three-dimensional distribution of temperature, salinity, and chemical constituents, including the carbonate system parameters will be mapped. Knowledge of these parameters and their initial conditions will allow determination of heat and water transports as well as carbon transport. An understanding of these transports will contribute to the understanding of processes which are relevant for climate change. This section in the South Atlantic subtropical Gyre is especially relevant for CO{sub 2} transport because it crosses both the Brazil and the Benguela Boundary Currents

Carbon dioxide, hydrographic, and chemical data obtained during the R/V Meteor Cruise 18/1 in the North Atlantic Ocean (WOCE Section A1E, September 1991)

The North Atlantic Ocean is characterized by an intense meridional circulation cell carrying near-surface waters of tropical and subtropical origin northward and deep waters of arctic and subarctic origin southward. The related {open_quotes}overturning{close_quotes} is driven by the sinking of water masses at high latitudes. The overturning rate and thus the intensity of the meridional transports of mass, heat, and salt, is an important control parameter for the modeling of the ocean`s role in climate. The Research Vessel (R/V) Meteor Cruise 18/1 was one in a series of cruises in the North Atlantic that started in March 1991 and continued until 1995. This data documentation discusses the procedures and methods used to measure total carbon dioxide (TCO{sub 2}) and total alkalinity (TALK) at hydrographic stations, as well as underway partial pressure of CO{sub 2} (pCO{sub 2}) measured during the RIV Meteor Cruise 18/1 in the North Atlantic Ocean (Section A1E). Conducted as part of the World Ocean Circulation Experiment (WOCE) and the German North Atlantic Overturning Rate Determination expedition, the cruise began in Reykjavik, Iceland, on September 2, 1991, and ended after 24 days at sea in Hamburg, Germany, on September 25, 1991. WOCE Zonal Section AlE began at 60{degrees}N and 42{degrees}30{prime} W (southeast of Greenland) and continued southeast with a closely spaced series of hydrocasts to 52{degrees}20{prime} N and 14{degrees}15{prime} W (Porcupine Shelves). Measurements made along WOCE Section AlE included pressure, temperature, salinity, and oxygen measured by a conductivity, temperature and depth (CTD) sensor; bottle salinity; oxygen; phosphate; nitrate; nitrite; silicate; TCO{sub 2}; TALK; and underway pCO{sub 2}. A total of 61 CTD casts were made, including 59 bottle casts and 2 calibration stations

Carbon dioxide, hydrographic, and chemical data from the F/S Meteor Cruise No. 18 in the North Atlantic Ocean (WOCE Section A1/E) during September 1991

This report presents the procedures and methods used to obtain total carbon dioxide (C{sub T}), total alkalinity, and underway pCO{sub 2} data during the F/S Meteor Cruise 18 in the North Atlantic Ocean (WOCE Section A1/E). The F/S Meteor departed Reykjavik on September 2, 1991 and docked in Hamburg early on the morning of September 25, 1991 after 24 days at sea. A two day steam from Reykjavik brought the ship to the starting position for WOCE zonal section A1/east (A1/E) on September 5. Section work began and ended with a closely spaced series hydrocasts on the SE-Greenland (60{degree}N 42{degree}30 minutes W) and Porcupine Shelves (52{degree}20 minutes N 14{degree}15 minutes W), respectively. The cast schedule was interrupted for equipment problems (6 and 7 September), current meter deployments (9, 10, 11, 14, and 19 September), and by high seas (13, 14, and 17 September). Of 64 CTD casts made, 58 were bottle casts including two calibration stations. Measurements made included CTD pressure, temperature, salinity, bottle salinity, oxygen, phosphate, nitrate, nitrite, silicate, total alkalinity, CFC`S, total carbon dioxide, and continuous underway pCO{sub 2} of surface waters. Carbonate samples were collected from 31 section stations (55.4% of the section stations), one test station, and two calibration stations. Repeated XBT, and ADCP profiles were taken throughout the cruise. Instructions for accessing the data are provided

Estimating mixed layer nitrate in the North Atlantic Ocean

Here we present an equation for the estimation of nitrate in surface waters of the North Atlantic Ocean (40° N to 52° N, 10° W to 60° W). The equation was derived by multiple linear regression (MLR) from nitrate, sea surface temperature (SST) observational data and model mixed layer depth (MLD) data. The observational data were taken from merchant vessels that have crossed the North Atlantic on a regular basis in 2002/2003 and from 2005 to the present. It is important to find a robust and realistic estimate of MLD because the deepening of the mixed layer is crucial for nitrate supply to the surface. We compared model data from two models (FOAM and Mercator) with MLD derived from float data (using various criteria). The Mercator model gives a MLD estimate that is close to the MLD derived from floats. MLR was established using SST, MLD from Mercator, time and latitude as predictors. Additionally a neural network was trained with the same dataset and the results were validated against both model data as a "ground truth" and an independent observational dataset. This validation produced RMS errors of the same order for MLR and the neural network approach. We conclude that it is possible to estimate nitrate concentrations with an uncertainty of ±1.4 ?mol L?1 in the North Atlantic.<br/

Modeling vertical oxygen and carbon flux during stratified spring and summer conditions on the continental shelf, Middle Atlantic Bight, eastern U.S.A

The Shelf Edge Exchange Processes II (SEEP-II) program was designed to examine the potential for export of organic carbon from the continental shelf to the deeper ocean. In the Middle Atlantic Bight of the east coast, U.S.A., a “cold pool” of relict winter water is isolated by the development of a strong seasonal thermocline on the shelf. Oxygen concentrations were monitored in and above the cold pool from March 1988 to May 1989, with electrodes moored at 19 and 38 m at a 42-m station off the Delmarva Peninsula, eastern U.S.A. An oxygen-flux simulation model was constructed to describe long-term changes in oxygen concentration and saturation. The model utilized biological rate and biomass measurements obtained at the mooring location during cruises. Vertical eddy diffusion was constrained by comparison with the redistribution of chlorofluorocarbons and heat after stratification, and by sensitivity analyses. Model predictions of the average daily change in oxygen concentration and saturation at 38 m were in good agreement with average changes recorded by moored oxygen sensors, when biological generation of oxygen was approximately equal to the thermotrophic consumption. Strong, but transient, fluctuations concentration and saturation were clearly associated with specific advective events, and had little lasting impact on the overall long-term trends. Consequently, model parameters derived from intermittent, cruise-based observations yielded satisfactory predictions of long-term trends. A carbon budget was constructed for the stratified summer period from data that largely overlapped with those used for the oxygen model. The continental shelf ecosystem operates in approximate balance during the summer, with a potential export of no more than 4% of primary production

The seasonal pCO2 cycle at 49°N/16.5°W in the northeastern Atlantic Ocean and what it tells us about biological productivity

A 2-year record of mixed layer measurements of CO2 partial pressure (pCO2), nitrate, and other physical, chemical, and biological parameters at a time series site in the northeast Atlantic Ocean (49°N/16.5°W) is presented. The data show average undersaturation of surface waters with respect to atmospheric CO2 levels by about 40 ± 15 ?atm, which gives rise to a perennial CO2 sink of 3.2 ± 1.3 mol m?2 a?1. The seasonal pCO2 cycle is characterized by a summer minimum (winter maximum), which is due to the dominance of biological forcing over physical forcing. Our data document a rapid transition from deep mixing to shallow summer stratification. At the onset of shallow stratification, up to one third of the mixed layer net community production during the productive season had already been accomplished. The combination of high prestratification productivity and rapid onset of stratification appears to have caused the observed particle flux peak early in the season. Mixed layer deepening during fall and winter reventilated CO2 from subsurface respiration of newly exported organic matter, thereby negating more than one third of the carbon drawdown by net community production in the mixed layer. Chemical signatures of both net community production and respiration are indicative of carbon overconsumption, the effects of which may be restricted, though, to the upper ocean. A comparison of the estimated net community production with satellite-based estimates of net primary production shows fundamental discrepancies in the timing of ocean productivity

MATLAB Program Developed for CO2 System Calculations. ORNL/CDIAC-105b.

This is a MATLAB-version of the original CO2SYS for DOS. CO2SYS calculates and returns a detailed state of the carbonate system of oceanographic water samples, if supplied with enough input. Use this function as you would use any other Matlab inline funtion, i.e., a=func(b,c). For extended details on using the function, please refer to the enclosed help by typing "help CO2SYS" in Matlab. For details on the internal workings of the function, please refer to the original publication of Lewis and Wallace at http://cdiac.ornl.gov/oceans/co2rprt.html. Note that this function allows for the input of vectors. This means that you can calculate many samples at once. Each of these samples can be processed with individual salinities, temperatures, pH scales, dissociation constants, etc