Average concentrations and trends of surface chlorophyll-a in transitional, coastal and marine waters surrounding Europe

Figure Created 04 Aug 2022 Published 04 Aug 2022 Last modified 25 Aug 2022
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Summer surface chlorophyll-a concentration averages (left) and trends (right), in locations recently updated (last update>2015) with at least 5 years of observations, in the period between 1980 and 2019. Colour keys of symbols and values are included in the legend.

European data


Additional information

• Average chlorophyll-a concentrations were calculated using data from observations in summer (May to September) from the upper 10m of the water column, in locations with annual data for the last 5-year period (2015-2019), transformed to the logarithmic scale.
• Data were aggregated into squares of 0.01 degree × 0.01 degree for coastal stations (within 20km of the coastline) and 0.05 degree × 0.05 degree for open water stations.
• Temporal trends were estimated in locations with data for at least 5 years in the period 1980-2019 and updated in the last 5-year period (2015-2019), using the non-parametric Mann-Kendall test. A p-value of <0.05 was considered to indicate a statistically significant trend.
• Results reflect data availability, which may vary significantly across regions and over time.

Temporal coverage
1980-2019  (the temporal range specified is the maximum range of dates for raw observations but this range varies upon the availability of observations at each location).

Geographical coverage
European marine regions - Greater North Sea, Baltic Sea, Bay of Biscay and the Iberian Coast, Celtic Seas, Mediterranean Sea, Black Sea, North-East Atlantic Ocean and Macaronesia


Geographic coverage

Temporal coverage

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