Marine heatwaves and cold-spells in the North Sea (1993-2019)

Marine heatwave and cold-spells for the North Sea (4°W to 10°E, 51°N to 62°N) during the period 1993 to 2019 were identified using ocean temperatures from model simulations. The study used products NORTHWESTSHELF_REANALYSIS_PHYS_004_009 (for 1993 to 2018) and NORTHWESTSHELF_ANALYSIS_FORECAST_PHYS_004_001_B (for 2019) downloaded in January 2020 from the E.U. Copernicus Marine Service (https://data.marine.copernicus.eu/products). Quality information for the model simulations is available from the Copernicus website*.

Timeseries of daily near-bed and near-surface temperatures were averaged over each International Council for the Exploration of the Sea (ICES) rectangle (ICES, 1977) in the North Sea. Marine heatwave and cold-spells were identified by the method of Hobday et al. (2016) using code downloaded from https://github.com/ecjoliver/marineHeatWaves. The daily temperatures were used to calculate a climatological (mean) annual cycle and the 10th and 90th percentiles for 1993–2019, which were then smoothed using a 31-day moving mean. Marine heatwaves are identified as periods of at least five consecutive days when the temperature exceeds the threshold of the 90th percentile and marine cold-spells are periods of five or more days when the temperature is lower than the 10th percentile.

The data were used in a study of marine heatwaves and cold-spells in the North Sea, and their impact on fisheries (Section 3.2 in von Schuckmann et al., 2018).

The dataset consists of four files:

filename

description

1

V1_near_bed_cold_events_10pc.csv 

near-bed marine cold-spells

2

V1_near_surface_cold_events_10pc.csv

near-surface marine cold-spells

3

V1_near_bed_heat_events_90pc.csv 

near-bed marine heatwaves

4

V1_near_surface_heat_events_90pc.csv

near-surface marine heatwaves

Acknowledgment

The work was supported by the Copernicus Marine Environment Monitoring Service (CMEMS).

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*Product User Manuals (PUMs) and Quality Information Documents (QuIDs) for the model simulations

1. NORTHWESTSHELF_REANALYSIS_PHYS_004_009

PUM: http://marine.copernicus.eu/documents/PUM/CMEMS-NWS-PUM-004-009.pdf   

QuID: http://marine.copernicus.eu/documents/QUID/CMEMS-NWS-QUID-004-009.pdf

2. NORTHWESTSHELF_ANALYSIS_FORECAST_PHYS_004_001_B

PUM: http://marine.copernicus.eu/documents/PUM/CMEMS-NWS-PUM-004-001.pdf

QuID http://marine.copernicus.eu/documents/QUID/CMEMS-NWS-QUID-004-001-b.pdf