Abstract
Abstract. The Global Ocean Data Analysis Project (GLODAP) is a synthesis effort providing regular compilations of surface to bottom ocean biogeochemical data, with an emphasis on seawater inorganic carbon chemistry and related variables determined through chemical analysis of water samples. This update of GLODAPv2, v2.2019, adds data from 116 cruises to the previous version, extending its coverage in time from 2013 to 2017, while also adding some data from prior years. GLODAPv2.2019 includes measurements from more than 1.1 million water samples from the global oceans collected on 840 cruises. The data for the 12 GLODAP core variables (salinity, oxygen, nitrate, silicate, phosphate, dissolved inorganic carbon, total alkalinity, pH, CFC-11, CFC-12, CFC-113, and CCl4) have undergone extensive quality control, especially systematic evaluation of bias. The data are available in two formats: (i) as submitted by the data originator but updated to WOCE exchange format and (ii) as a merged data product with adjustments applied to minimize bias. These adjustments were derived by comparing the data from the 116 new cruises with the data from the 724 quality-controlled cruises of the GLODAPv2 data product. They correct for errors related to measurement, calibration, and data handling practices, taking into account any known or likely time trends or variations. The compiled and adjusted data product is believed to be consistent to better than 0.005 in salinity, 1 % in oxygen, 2 % in nitrate, 2 % in silicate, 2 % in phosphate, 4 µmol kg−1 in dissolved inorganic carbon, 4 µmol kg−1 in total alkalinity, 0.01–0.02 in pH, and 5 % in the halogenated transient tracers. The compilation also includes data for several other variables, such as isotopic tracers. These were not subjected to bias comparison or adjustments. The original data, their documentation and DOI codes are available in the Ocean Carbon Data System of NOAA NCEI (https://www.nodc.noaa.gov/ocads/oceans/GLODAPv2_2019/, last access: 17 September 2019). This site also provides access to the merged data product, which is provided as a single global file and as four regional ones – the Arctic, Atlantic, Indian, and Pacific oceans – under https://doi.org/10.25921/xnme-wr20 (Olsen et al., 2019). The product files also include significant ancillary and approximated data. These were obtained by interpolation of, or calculation from, measured data. This paper documents the GLODAPv2.2019 methods and provides a broad overview of the secondary quality control procedures and results.
Highlights
The oceans mitigate climate change by absorbing CO2 corresponding to a significant fraction of anthropogenic CO2 emissions (Gruber et al, 2019; Le Quéré et al, 2018) and most of the excess heat in the Earth system caused by the enhanced greenhouse effect resulting from the fraction of CO2 and other greenhouse gases remaining in the atmosphere (Cheng et al, 2017)
The objective of GLODAP (Global Ocean Data Analysis Project, https://www.glodap.info/, last access: 17 September 2019) is to ensure provision of highquality and bias-corrected water column bottle data from the ocean surface to bottom that document the evolving changes in physical and chemical ocean properties ascribed to global change, e.g., the inventory of the excess CO2 in the ocean, natural oceanic carbon, ocean acidification, ventilation rates, oxygen levels, and vertical nutrient transports
The additional cruises include many collected within the framework of the “repeat hydrography” program (Talley et al, 2016), instigated in the early 2000s as part of CLIVAR and since 2007 organized as the Global Ocean Ship-based Hydrographic Investigations Program (GO-SHIP)
Summary
The oceans mitigate climate change by absorbing CO2 corresponding to a significant fraction of anthropogenic CO2 emissions (Gruber et al, 2019; Le Quéré et al, 2018) and most of the excess heat in the Earth system caused by the enhanced greenhouse effect resulting from the fraction of CO2 and other greenhouse gases remaining in the atmosphere (Cheng et al, 2017). The first version of GLODAP, GLODAPv1.1, was released in 2005 (Key et al, 2004; Sabine et al, 2005) It contains data from 115 cruises with biogeochemical measurements from the global ocean. The additional cruises include many collected within the framework of the “repeat hydrography” program (Talley et al, 2016), instigated in the early 2000s as part of CLIVAR and since 2007 organized as the Global Ocean Ship-based Hydrographic Investigations Program (GO-SHIP) Both GLODAPv1.1 and GLODAPv2 data were released in three formats: (i) as submitted by the data originator but reformatted to WOCE exchange format (Swift and Diggs, 2008) and subjected to primary quality control to flag outliers, (ii) as a merged data product with bias minimization adjustments applied, and (iii) as globally mapped climatological distributions. It forms the basis for the documentation of future updates, adopting the Earth System Science Data “living data” format for evolving data sets
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