Evidence of wind‐driyen upwelling in jacques‐cartier strait

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Abstract
Satellite images of the Gulf of St. Lawrence show a persistent band of cold water along the north coast of Jacques‐Cartier Strait during summer. A possible explanation is that the wind is causing upwelling of deep water. The upwelling hypothesis is tested here by comparing along‐shore wind stress tinte series τr(t) with upwelling velocity w(t) inferred front moored température data with a régression model. The results support the upwelling hypothesis. For periods exceeding 1.5 d (e.g. wind‐event periods), the average spectral coherency between along‐shore wind stress and inferred upwelling velocity is 0.76, which exceeds the 5% significance level of 0.52. The cross‐shore length scale of upwelling, L, inferred from combining the transfer function between w and τx with the upwelling model, w = τx /ρ f L, was calculated as 4 to 7 km. This is comparable to the Rossby radius, further supporting the upwelling hypothesis.