ON THE DYNAMICAL RESPONSE OF THE SUBARCTIC FRONT TO MOMENTUM TRANSFER

• Other Authors: CAMERLENGO, ALEJANDRO LIVIO., Florida State University
• Format: Text
• Language: unknown
• Published: 1981
• Subjects: Physical Oceanography; Curl; Subarctic
• Online Access: https://diginole.lib.fsu.edu/islandora/object/fsu%3A74393/datastream/TN/view/ON%20THE%20DYNAMICAL%20RESPONSE%20OF%20THE%20SUBARCTIC%20FRONT%20TO%20MOMENTUM%20TRANSFER.jpg

Theoretical studies and numerical experiments of the subarctic front are conducted. The theoretical side of this research encompasses the determination of a stability criterion and the role friction plays as a dissipative mechanism. In the first case study, it is established that if the difference between the phase speed of the perturbation and the mean long-front geostrophic flow is greater than a certain value, the subarctic front is stable everywhere. In the other case study, it is proved that the time scale of dissipation is sufficiently large to neglect horizontal friction. While the effect of the westerly winds causes a southward shift of the front, the effect of a negative curl shows convergence at the front. This convergence strongly favors frontogenesis. It is established that the phase speed of the first baroclinic mode is larger in a numerical model where a constant density jump between layers is employed. Thus, a smaller time scale is required to avoid the numerical instability caused by the violation of the CFL criterion. A numerical four-layer hydrodynamical model is implemented to investigate the role the atmosphere exerts on the dynamics of the subarctic front. The salient features at the wake of a strong cyclone can be summarized as follows: (i) upwelling of 20 meters of the four interfaces occurs; (ii) the water remains upwelled for several weeks; (iii) the e-folding time scale of the vertical oscillations induced by the storm's passage is of the order of 10 days; (iv) a region of relative maximum convergence is observed in the lower layers below a region of relative maximum upwelling in the upper layer; and (v) the long and cross-front velocity fields are in quadrature in time, with the cross front velocity lagging the long front velocity. With the exception of the cyclone's case, it is established that the effects of the atmospheric wind forcing are confined to the upper layer. These results are supported by oceanic observations. Finally, it is also proved that the response of the front ...