Planetary waves and circulation in a polar basin
Professor Andrew J. Willmott - Professor of Physical Oceanography and Head of School, School of Marine Science and Technology, Newcastle University
Analytical solutions for barotropic vorticity wave dynamics and planetary geostrophic ocean circulation in a polar basin on the rotating Earth are few and far between in the refereed literature. This is because the meridional gradient of the Coriolis parameter varies linearly with latitude and this, in turn, leads to a linearised barotropic vorticity equation with coefficients that vary with latitude in a complicated way. However, I will discuss an overlooked approximation in the refereed literature of the seventies that allows approximate analytical solutions of this equation to be obtained. Some examples that I will highlight are:
- A new method for deriving the approximate form for the dispersion relation of divergent barotropic planetary waves in a polar basin with a commentary about its strengths and weaknesses
- Steady source-sink and wind stress curl driven circulation in a polar basin with a step shelf
To extend the above process model solutions to those which are more representative of the Arctic Ocean, the NEMO numerical ocean general circulation model is used to study the role of more realistic topography and unsteady forcing on the planetary geostrophic circulation. In particular, I will highlight the structure of the sea surface height (SSH) anomaly field associated with unsteady transport through the straits connecting the Arctic Ocean to its marginal seas. Can knowledge of the SSH anomaly field be used to infer the transport in these straits?