Environmental statement - Flyndre and Cawdor - Maersk Oil

3.1.2. OFFSHORE CLIMATE
Flyndre and Cawdor Environmental Statement
Section 3 Environmental Baseline
The CNS is situated in temperate latitudes with a climate that is strongly influenced by the inflow of
oceanic water from the Atlantic Ocean and by a large‐scale westerly air circulation, which frequently
contains low pressure systems (OSPAR Commission, 2000). The extent of this influence varies over
time as changes in the strength and persistence of the westerly winds are influenced by the winter
North Atlantic Oscillation (a pressure gradient between Iceland and the Azores).
Wind speed and direction directly influence the transport and dispersion of atmospheric emissions
from an installation. These factors are also important for the dispersion of marine emissions,
including oil spills, by affecting the movement, direction and break up of substances on the sea
surface. Wind data spanning 140 years (1854‐1994) across the North Sea show the occurrence of
winds from all directions, with those from the south‐south‐west and south dominating. Predominant
wind speeds throughout the year represent moderate to strong breezes (6 ‐ 13 m/s) with the highest
frequency of gales (>17.5 m/s) during winter months (November–March). The major contrast
between the NNS and central and southern areas is the relative frequency of strong winds and gales,
particularly from the south. In northern areas (north of 57 o N) the percentage frequency of winds of
Beaufort force 7 and above in January is >30% but 30% (DTI, 2001).
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