Abstract
Abstract. The datasets described here bring together quality-controlled seawater temperature measurements from over 130 years of departmental government-funded marine science investigations in the UK (United Kingdom). Since before the foundation of a Marine Biological Association fisheries laboratory in 1902 and through subsequent evolutions as the Directorate of Fisheries Research and the current Centre for Environment Fisheries & Aquaculture Science, UK government marine scientists and observers have been collecting seawater temperature data as part of oceanographic, chemical, biological, radiological, and other policy-driven research and observation programmes in UK waters. These datasets start with a few tens of records per year, rise to hundreds from the early 1900s, thousands by 1959, and hundreds of thousands by the 1980s, peaking with > 1 million for some years from 2000 onwards. The data source systems vary from time series at coastal monitoring stations or offshore platforms (buoys), through repeated research cruises or opportunistic sampling from ferry routes, to temperature extracts from CTD (conductivity, temperature, depth) profiles, oceanographic, fishery and plankton tows, and data collected from recreational scuba divers or electronic devices attached to marine animals. The datasets described have not been included in previous seawater temperature collation exercises (e.g. International Comprehensive Ocean–Atmosphere Data Set, Met Office Hadley Centre sea surface temperature data set, the centennial in situ observation-based estimates of sea surface temperatures), although some summary data reside in the British Oceanographic Data Centre (BODC) archive, the Marine Environment Monitoring and Assessment National (MERMAN) database and the International Council for the Exploration of the Sea (ICES) data centre. We envisage the data primarily providing a biologically and ecosystem-relevant context for regional assessments of changing hydrological conditions around the British Isles, although cross-matching with satellite-derived data for surface temperatures at specific times and in specific areas is another area in which the data could be of value (see e.g. Smit et al., 2013). Maps are provided indicating geographical coverage, which is generally within and around the UK Continental Shelf area, but occasionally extends north from Labrador and Greenland to east of Svalbard and southward to the Bay of Biscay. Example potential uses of the data are described using plots of data in four selected groups of four ICES rectangles covering areas of particular fisheries interest. The full dataset enables extensive data synthesis, for example in the southern North Sea where issues of spatial and numerical bias from a data source are explored. The full dataset also facilitates the construction of long-term temperature time series and an examination of changes in the phenology (seasonal timing) of ecosystem processes. This is done for a wide geographic area with an exploration of the limitations of data coverage over long periods. Throughout, we highlight and explore potential issues around the simple combination of data from the diverse and disparate sources collated here. The datasets are available on the Cefas Data Hub (https://www.cefas.co.uk/cefas-data-hub/). The referenced data sources are listed in Sect. 5.
Highlights
The measurement of surface and subsurface seawater temperature has been a standard activity for a significant proportion of marine researchers for the past 200 years
Temperature minima in winter are typically 9 to 10 ◦C at the shelf edge but 6 to 9 ◦C elsewhere; they depend on the weather in any one year, on depth, and on travel time for any Atlantic water arriving from the shelf edge
The use of data from the Cefas Data Hub requires that the correct and appropriate interpretation is solely the responsibility of the data users, that results, conclusions, and/or recommendations derived from the data do not imply endorsement from Cefas, that data sources must be acknowledged, preferably using a formal citation, that data users must respect all restrictions on the use of data such as for commercial purposes, and that data may only be redistributed, i.e. made available in other data collections or data portals, with the prior written consent of Cefas. This data rescue, assembly, integration, and publication exercise stemmed from what seemed at the time to be a relatively simple plea made at an internal workshop to make all temperature datasets held within the Lowestoft laboratory available via a common data portal
Summary
The measurement of surface and subsurface seawater temperature has been a standard activity for a significant proportion of marine researchers for the past 200 years. Subtle differences in the methodologies for calibrating such disparate measurements have been found to greatly impact reconstructions of time series of global climate warming (Karl et al, 2015) Both issues with ship data sources have been identified, including the change from bucket samples to engine intake thermometers, and more relevant here, the increase in data density with time as buoy-mounted observation systems were deployed as sources of time-dependant bias in the global SST record. Two data sources are from citizen science, the Coastal Temperature Network (CTN), which was established in the mid1960s (with individual datasets going back over 100 years), preceded the term whilst relying on volunteers The majority of these temperature datasets have been previously analysed and integrated into a myriad of diverse and disparate reports and scientific papers, often in the form of summary tables and figures or as contributions to understanding the environment of fish and other biota. The Cefas Data Hub currently holds published data in source formats with the intention of making these and other datasets more accessible by using transformations similar to those executed here
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