CARINA Data Synthesis Project

By The CARINA Group

The CARINA (CARbon dioxide IN the Atlantic Ocean) data synthesis project is an international collaborative effort of the EU IP CARBOOCEAN, and US partners. It has produced a merged internally consistent data set of open ocean subsurface measurements for biogeochemical investigations, in particular, studies involving the carbon system. The original focus area was the North Atlantic Ocean, but over time the geographic extent expanded and CARINA now includes data from the entire Atlantic, the Arctic Ocean, and the Southern Ocean. Carbon data from the Pacific Ocean are being synthesized in the PICES effort.

The CARINA database includes data from 188 cruises. The salinity, oxygen, nutrient, inorganic carbon system and CFC data have been subjected to extensive quality control and adjustments have been made when necessary. The internally consistent data are available as three data products, one each for the Arctic Mediterranean Seas, the Atlantic and the Southern Oceans (CARINA Data Products). In addition, all of the individual cruise data files have been made available in WOCE exchange format in a single location (Cruise Summary Table) along with metadata and references. We strongly recommend users to employ the data products instead of the individual cruise files as the data in the latter have not been corrected for biases identified during the secondary QC. The CARINA effort is further described in the following as well as in the CARINA special issue of Earth System Science Data (ESSD) Journal.

History of the CARINA project

The CARINA project began as an informal collaboration with limited funding. The project was started by D. Wallace and L. Mintrop, and had an organizational meeting at Delmenhorst, Germany in 1999. Mintrop acted as data collector. Participation was voluntary and composed mainly of European scientists. Participating scientists were required to submit their historical data sets that included either subsurface carbon system measurements or underway surface pCO2 data. The last meeting of this group was held in 2002. By that time the group had accumulated subsurface data from approximately 30 cruises (excluding those cruises that were in GLODAP) and twice that number of underway data sets. The funding ended in 2003 and, unfortunately, the support level was insufficient to do much more than amass and catalog the submitted data (Original CARINA website).

In 2004 the original CARINA data collection was transferred to Carbon Dioxide Information Analysis Center (CDIAC) and a copy of the CARINA bottle data was transferred to Princeton for data assessment and quality control.

In January 2005 the E.U. funded CARBOOCEAN program began. This consortium includes most of the original CARINA scientists. CARBOOCEAN is an integrated program with the aim of making an accurate assessment of oceanic sources and sinks of carbon over space and time. It has focus on the Atlantic and Southern Ocean and a time interval of -200 to +200 years from the present. All funded CARBOOCEAN partners are required to make public all historical data and new data after a two year proprietary period. In June, 2006 the CARBOOCEAN/CARINA scientists met in Laugarvatn, Iceland to discuss methods and responsibilities for the CARINA data synthesis. By that time, the CARINA collection had grown to approximately 80 cruises. During this meeting the group decided to extend the original scope of CARINA to include the entire Atlantic, the Arctic and the Southern Ocean. Various team and project leader assignments were:

Data collection, 1st QC and production of final data products: R. Key and X. Lin
Atlantic Ocean: T. Tanhua
Arctic Ocean: S. Jutterström
Nordic Seas: A. Olsen
Southern Ocean: M. Hoppema
2nd QC code development: S. van Heuven
Web site development and maintenance: C. Schirnick
Carbon calculation software: A. Velo
CDIAC data archive: A. Kozyr

The team also decided to include data from CLIVAR cruises that were final and that were in any of the focus regions. Since the new CLIVAR data were known to be high quality, those data, along with WOCE results would serve as "master cruises" for the data calibration (2nd QC) phase of the synthesis. The areal expansion of the project led to a flood of new data and a final total of 188 "cruises".

CARINA Data assembly and synthesis

Many of the procedures used during CARINA were adopted from GLODAP, however, the number of cruises included in CARINA combined with the additional manpower and funding available from CARBOOCEAN allowed improvements. The most significant changes were:

  • more parameters were subjected to 2nd QC;
  • software was designed to automate portions of the 2nd QC procedures;
  • work was coordinated among the different groups and within groups by means of a Web site;
  • pH was included in the final data products along with ALK and DIC;
  • fully formatted versions of all the individual cruise files were submitted to both CCHDO and CDIAC for archive and distribution; and
  • a significant collection of references to literature describing the individual cruise results was compiled.

This effort created two distinct results. The first is a set of individual cruise files with the measured data converted to common units and accompanying metadata. The second is a set of 3 data products (Arctic Mediterranean Seas, Atlantic and Southern Ocean) that have been fully calibrated and include some calculated values. The latter are compatible with the three GLODAP data products (Atlantic, Indian and Pacific).

Details of the CARINA procedures and calibration results are available on-line and have been published in a series of articles in Earth System Science Data. (To Alex, make this a link)

It is important to note that, while individual CARINA scientists were involved in many of the cruises included in the CARINA data products, the CARINA team does not deserve credit for the individual cruise data sets. That credit belongs to the individuals who originally generated the data. What we have done is to assemble the original data, submit the original data to public Web sites, and most importantly, create the merged calibrated data products.

Atlantic Ocean Data Synthesis

The Atlantic Ocean subset of the CARINA (CARINA-ATL) data set consists of 98 cruises/entries, of which one of is a time series including many cruises and two others are collections of multiple cruises within the framework of a common project. Additionally, six reference cruises were included in the secondary QC for CARINA-ATL to ensure consistency between CARINA and historical databases, in particular Global Ocean Data Analysis Project (GLODAP, Key et al., 2004). FiveAtlantic cruises are in common with the Southern Ocean region, and five others are in common with the Arctic Mediterranean Seas region. These overlapping cruises ensure consistency between the three regions of the CARINA data set. The Atlantic Ocean region of CARINA is loosely defined as the area between of the Greenland-Scotland Ridge and 30 °S, but as mentioned, ten cruises overlap with the surrounding regions, thus extending the area covered. Most of the data are from the subpolar North Atlantic, and there are particularly large data gaps in the Tropical and South-Eastern Atlantic Ocean. The CARINA-ATL database covers the time period from 1978 to 2006, with the majority of the data from the mid 1990s to the mid 2000s. Overall, oxygen measurements show the highest incidence, followed by TCO2, Alkalinity and CFC data, although CFC data are particularly abundant for some specific regions.

Arctic Mediterranean Seas Data Synthesis

The Arctic Mediterranean Seas subset of CARINA (CARINA-AMS) includes data from 62 cruises/campaigns in the Arctic Ocean and Nordic Seas. One of these is a time series and one is a collection of data from multiple cruises to the same area conducted within a year. Five of the CARINA-AMS entries are in common with the CARINA-ATL subset ensuring consistency with the other CARINA subsets and thus GLODAP. While data coverage was quite dense in the Nordic Seas, it was sparse in the Arctic Ocean. This motivated the use of different methods for quality control in these two areas. The Arctic Ocean was defined as the region north of the Fram and Bering Straits, the Arctic Ocean shelf seas, and the Canadian Archipelago. The Nordic Seas was defined as the region enclosed by the Fram Strait to the North, Greenland to the west, the Greenland-Scotland Ridge to the South, and Norway, the Barents Sea Opening, and Spitsbergen to the east. The analyses of the Arctic Ocean data involved extended use of linear and multiple linear regressions and is described by Jutterström et al. (2009), while the analyses of the Nordic Seas data was mostly carried out using the crossover and inversion approach and is described per parameter in Falck and Olsen (2009), Olafsson and Olsen (2009), Olsen (2009), Olsen (2009) and Olsen et al.(2009). The analyses of the AMS CFC data are described by Jeansson et al. (2009).

Southern Ocean Carbon Synthesis

Compared to other regions within the CARINA data set, the Southern Ocean database consists of relatively few data - 37 cruises. Five cruises in the northern part of the Atlantic sector of the Southern Ocean are in common with the CARINA-ATL, thus additionally warranting high internal data quality. The northern boundary of the CARINA Southern Ocean region is roughly at 30°S latitude. Considering all stations in the Southern Ocean CARINA dataset there is a bias towards the north, indicating that data close to the Antarctic continent is still sparse. Besides the new CARINA cruises, 46 cruises from the GLODAP database were incorporated in the analysis as reference cruises. Nutrient and oxygen data have a clearly higher incidence than TCO2 and total alkalinity data. Chlorofluorocarbons (CFCs) are also included in the Southern Ocean dataset, but they have not been quality controlled. Not surprisingly, most of the CARINA Southern Ocean data originate from the post-GLODAP era, i.e., from 2000 or later. Region specific quality control is described in three papers, for the Pacific sector by Sabine et al. (2009), the Indian sector by Lo Monaco et al. (2009) and the Atlantic sector by Hoppema et al. (2009).

An expanded version of the information contained here is available in the CARINA Numeric Data Package (NDP-091).

A complete listing of the CARINA publications can be found here.

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