Wind-driven variability of the large-scale recirculating flow in the Nordic Sea and Arctic Ocean

• Main Authors: Pa L E. Isachsen, J. H. Lacasce, C. Mauritzen, S. Ha Kkinen
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2003
• Subjects: Arctic; Arctic Ocean; Greenland; Greenland Sea; Nordic Sea; Nordic Seas; North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.615.8419; http://met.no/Forskning/Vare_forskere/Cecilie_Mauritzen/filestore/Isachsen_LaCasce_Mauritzen_Hakkinen_JPO2003.pdf

The varying depth-integrated currents in the Nordic seas and Arctic Ocean are modeled using an integral equation derived from the shallow-water equations. This equation assumes that mass divergence in the surface Ekman layer is balanced by convergence in the bottom Ekman layer. The primary flow component follows contours of f /H. The model employs observed winds and realistic bottom topography and has one free parameter, the coefficient of the (linear) bottom drag. The data used for comparison are derived from in situ current meters, satellite altimetry, and a primitive equation model. The current-meter data come from a 4-yr record at 758N in the Greenland Sea. The currents here are primarily barotropic, and the model does well at simulating the variability. The ‘‘best’ ’ bottom friction parameter corresponds to a spindown time of 30–60 days. A further comparison with bottom currents from a mooring on the Norwegian continental slope, deployed over one winter period, also shows reasonable correspondence. The principal empirical orthogonal function obtained from satellite altimetry data in the Nordic seas has a spatial structure that closely resembles f /H. A direct comparison of this mode’s fluctuations with those predicted by the theoretical model yields linear correlation coefficients in the range 0.75–0.85. The primitive equation model is a coupled ocean–ice version of the Princeton Ocean Model for the North Atlantic and Arctic. Monthly mean depth-averaged velocities are calculated from a 42-yr integration