GEOGRAPHICAL VARIATIONS IN THE SEASONAL HEATING CYCLE IN NORTHWEST EUROPEAN SHELF SEAS

Geographical variations in the amplitude and phase of seasonal heat storage on the northwest European shelf have been determined by a least squares fit to monthly mean values of depth-integrated water temperature. The results are presented as maps. Many of the observed features can be explained in terms of local factors, such as water depth and the level of tidal stirring. The greatest heat storage occurs in regions of deep water with strong stirring, such as the English Channel and the Irish Sea. The phase varies by only 5 weeks over the whole shelf, with maximum heating occurring first in shallowest water. There is no evidence of any significant variation in heat storage with latitude, and the reasons for this are examined in terms of an analytical solution to a simplified set of heat flux equations. This solution shows that the annual mean temperature on the northwest European shelf should vary strongly with latitude, but that the amplitude of the seasonal cycle should vary only weakly with latitude, in agreement with observation. © 1990.