DOI: 10.14466/cefasdatahub.9
title: Cefas Fisheries Ecology Research Programme

description: This dataset has been extracted as part of an exercise to assemble "all" Cefas Temperature Data and publish it in a Data paper. It is one of 17 Cefas data sources assembled.

Diurnal and seasonal changes in water temperature in South Wales estuaries and saltmarshes.

Data were collected in 1995 and 1996 from three estuarine locations in South Wales during a study of the thermal experience and tolerance of estuarine animals. The data comprise hourly records of temperature in brackish water where the depth is <1 metre at low tide.

Three point locations in the Loughor Estuary, Oxwich Bay (Nicholstan Pill) and Swansea Bay (Black Pill) in South Wales. Positions were Loughor (51° 37.82’ N, 04° 13.54’ W), Oxwich Bay (51° 34.18’N, 04° 08.68’W) and Swansea Bay (51° 35.92’ N, 03° 59.61’ W) (WGS84, Plate carrée).

Point records, recorded hourly. Sensors fixed to bed of estuary or salt-marsh creek with less than one metre depth at low spring tides.

Resolution and Accuracy

VEMCO Minilog temperature recorder (Bedford, Nova Scotia, Canada) with resolution of ±0.1°C . Accuracy has been established in laboratory tests as ±0.3°C.

Data checked for outliers from the expected frequency and amplitude of variation by comparing absolute values with values generated by loess smoothing (various spans). Tidal model used to confirm the low probability that recorder was exposed to the air at low spring tides following deployment.

The depth-averaged model of the Bristol and English Channel was built with an unstructured triangular mesh, using the hydrodynamic software Telemac2D (v6p3) 1. The model domain extends 52.48°N – 48.02°N and 9.51°W – 2.23°E.

The unstructured mesh was discretised with 279,087 nodes and 544,356 elements. The mesh has a resolution of approximately 3km along the open boundaries and 500m along the coastlines. Bathymetry for the area was sourced from the DEFRA Digital Elevation Model (Astrium). The resolution of this dataset is 1 arc second (~30m) and referenced to Chart Datum.

The hydrodynamics are forced along the open boundaries using 11 tidal constituents (M2, S2, N2, K2, K1, O1, P1, Q1, M4, MS4 and MN4) from the OSU TPXO European Shelf 1/30° regional model [2].

The model is validated against 12 tide gauges sourced from the British Oceanographic Data Centre [3] at the following locations: St Mary’s, Newlyn, Devonport, Weymouth, Portsmouth, Newhaven, Dover, Milford Haven, Ilfracombe, Mumbles, Hinkley Point and St Heliers. The locations of the tide gauges are shown in Figure 31. Harmonic analysis of the model results shows good validation between the model and the tide gauges.

The model was run for the period 17/07/1995 00:00 to 06/11/1996 00:00, with free surface elevations recorded hourly.

For comparison with the temperature loggers, free surface elevations were extracted from the model results at the three locations: Oxwich (51° 33.90’ N, 04° 08.26’ W), Blackpill (51° 35.60’ N, 03° 58.51’ W) and Loughor (51° 38.99’ N, 04° 13.56’ W). The model’s free surface is referenced to variation around the sea surface. To use the model results with the temperature logger data, the free surfaces are transformed and referenced to the seabed.

The multiple sources are described in 17 separate metadata entries under the same Title, e.g. Seawater temperature records for the UK Shelf - 15 - RV Cefas Endeavour FerryBox Monitoring System. These data have been described in detail via the following publication. Morris, D. J., Pinnegar, J. K., Maxwell, D. L., Dye, S. R., Fernand, L. J., Flatman, S., Williams, O. J., and Rogers, S. I.: Over 10 million seawater temperature records for the United Kingdom Continental Shelf between 1880 and 2014 from 17 Cefas (United Kingdom government) marine data systems, Earth Syst. Sci. Data, 10, 27–51, https://doi.org/10.5194/essd-10-27-2018, 2018.