An Evolution of Algae Bloom Fields in the North Sea

An Evolution of Algae Bloom Fields in the North Sea

In late spring and early summer, algal blooms occur in various parts of the North Sea. The start of the the blooms varies by a few days from year to year. Observations must take into account that the airspace over the North Sea is often covered with opaque clouds, so that it is very often impossible to determine the exact time of occurrence of the observed phenomena by satellite.
Here is a brief history of the formation, development and spread/movement of Algal Bloom Fields (ABF) from mid-May to mid-July 2023 [s. Fig. 7].

From mid-May, an algal bloom field (ABF) spread westward from the Skagerrak around the southern coastline of Scandinavia.
Some ABFs formed in the Celtic Sea to the west and south of the Cornish Peninsula and in the southern path of the Irish Sea [s. Fig. 1].
The ABF formed in the southern North Sea near the West and East Frisian Islands. Emergences of the ABF over the Dogger Bank, in the centre of the North Sea between the Dogger Bank and the Danish west coast [s. Fig. 2], and over the Jutland Bank (the latter further drifting south/southwest) took place.
Further intensification of the Cornwall ABF bloom.

In early June, two adjacent ABFs form in the northern part of the North Sea around coordinates (57.5°N, 3°E) and (58.1°N, 1°E) between Scotland and Norway (Northern ABF).
A large ABF is forming north of the Hebrides [s. Fig. 3].
Formation of an ABF near Stavanger, Norway.
The northern ABF continues to expand to the west and northwest.
An ABFs between East of England (Norfolk) and West Coast of the Netherlands is forming.
The ABF southwest of Skagerrak is weakening.

From mid-June, the northern ABF spreads over the “Fladen Ground”. This then extends further northwest beyond the Shetlands.
The ABF northwest of Orkney Islands is forming.
The ABF near eastern Scotland (near Aberdeen) forms.
The ABF around the West Frisian Islands strengthens, and moves eastwards along the Frisian Islands [s. Fig. 6].
Weakening of the ABF in southwestern England.

Late June – large propagation of the northern ABF from a central location (from the “Fladen Ground”) to the north: towards Pobie Bank and Viking Bank [s. Fig. 5].
Formation of the ABF in the German Bight and its merging with the eastward spreading West Frisian ABF.

Early July – Northern ABF and West Frisian ABF continue to strengthen [s. Fig. 4, 5, 6].
Weakening of the ABF northeast of the Hebrides and the ABF northeast of the Orkney Islands.

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