Funds are provided to investigate a set of fundamental dynamical processes in the Arctic Ocean where the â-effect is small and the western ocean boundary is absent. Results will contribute to understanding a series of important issues concerning the circulation and state of the Arctic Ocean, such as: Does the Sverdrup balance hold in the Arctic? Do Rossby waves still play the central role in the spin up of an oceanic gyre in the Arctic? How does the ocean respond to changes in wind near the North Pole where Rossby waves are supposed to be nonexistent or stagnant? What role do eddies play in the potential vorticity balance? How does the ocean spin up to a quasi-equilibrium state if there is no western ocean boundary? Do winds or thermohaline factors dominate and shape the arctic?s ocean circulation? Why does the Atlantic water penetrate to the Arctic Ocean? Does it go to the Arctic to replace surface water forced by winds to go out of the Arctic (wind-driven theory) or in order to satisfy salt and heat balances (thermohaline theory)?

An accepted theory of ocean circulation has been developed over the past century based on studies of the subtropical and tropical gyres, such as the Gulf Stream system. The validity of the assumptions on which this theory is based is questionable in the Arctic Ocean. This study will enhance our understanding of the fundamental physics controlling Arctic Ocean circulation and our ability to predict the changes in circulation patterns that may result from changes in forcing and, hence, our ability to predict the drift of material in the Arctic Ocean.

Project Report

The Arctic Ocean circulations are special in a number of ways. Established ocean circulation theories do not apply in the Arctic Ocean. First, in a moderate latitude gyre, such as the subtropical gyre in the North Atlantic Ocean, the main balance in dynamics is the Sverdrup balance, namely between the wind stress curl and the advection of planetary vorticity - or the beta V term. In the Arctic the beta is very small because of its proximity to the North Pole. So beta V is expected to be small. Our study shows that it is the convergence of the eddy flux of vorticity that substitutes the beta term to balance the wind-stress curl term. Second, there is no western boundary in the Arctic Ocean. The western boundary is very important in any ocean circulation theory because western boundary currents, such as the Gulf Stream in the subtropical North Atlantic Ocean, dissipates the energy and vorticity imposed by the wind and also closes the gyre circulation by balancing the interior Sverdrup transport. It is found in our study that eddies transport vorticity and energy to narrow currents along the continental slopes in the Arctic Ocean where they are dissipated. This project addresses some fundamental and 0th order dynamics in idealized setting. The results shed some lights on key dynamics and help interpretations of more complicated 3-D model results and observations.

Agency
National Science Foundation (NSF)
Institute
Division of Polar Programs (PLR)
Type
Standard Grant (Standard)
Application #
1107412
Program Officer
William J. Wiseman, Jr.
Project Start
Project End
Budget Start
2011-08-01
Budget End
2014-07-31
Support Year
Fiscal Year
2011
Total Cost
$349,999
Indirect Cost
Name
Woods Hole Oceanographic Institution
Department
Type
DUNS #
City
Woods Hole
State
MA
Country
United States
Zip Code
02543