A criterion to locate regions with anticyclonic tidal current rotation

摘要

The equations of motion written in rotational form, with the rotary components of the velocity R+ (cyclonic) and R- (anticyclonic) and the rotary components of sea surface elevation gradients S+ (cyclonic) and S- (anticyclonic), are applied to investigate a link between sea surface amphidromic system and sense of rotation of tidal currents. It is shown that the assumptions S+ = S- or S+ = S- lead to a criterion to locate regions with anticyclonic tidal current rotation from co-tidal and co-range charts. Anticyclonic rotation seems to occur in regions where the gradients of sea surface elevation zeta and phase phi(zeta) tend to be parallel, i.e. where del zeta x del phi(zeta) = 0. It is also shown that this situation takes place in areas where the limits del zeta --> 0 and del phi(zeta) --> O exist, i.e, where co-tidal and co-range lines are quite separated. Results of numerical modelling of the M-2 tide in the North Sea and the Bohai Sea validate this prediction. (C) 2000 Elsevier Science Ltd. All rights reserved. [References: 10]