A new numerical solver for ocean models leads to more reliable climate simulations

Two scientists, Matthias Hofmann from the Potsdam Institute for Climate Impact Research (PIK) and Miguel Maqueda from the New York University (NYU), have discovered a conceptual weakness in ocean circulation models, which can cause a distorted representation of the ocean physics (Journal of Geophysical Research, 9 May 2006). They show that by upgrading the hitherto existing numerics for heat and salt transport by a clever algorithm (which already became standard in atmospheric modeling two decades ago) one can simulate a much more realistic ocean circulation.

10 May 2006

Since more than 70 % of the Earth surface is covered by water, our climate system is strongly governed by the dynamics of the ocean and its currents. Computer models which are regularly employed to predict the fate of the Earth's climate system rely on the correctness of their submodels, such as models of the ocean circulation.

Since data from the World Ocean Circulation Experiment (WOCE) became available, most oceanographers agree that most of the cold and salty water masses sinking down in the North Atlantic as part of the so called "conveyour belt" reappear at the sea surface in the Southern Ocean along the circumference of Antarctica.

Ocean models commonly used for climate predictions so far erroneously provided strong upwelling of North Atlantic Deep Water (NADW) at equatorial regions in the Pacific and Indian Ocean.

With the work by Hofmann and Maqueda, an algorithm is made available to the scientific community for the first time that delivers a remarkably improved model ocean physics with upwelling of NADW mostly occurring in the Southern Ocean combined with a more realistic distribution of temperature and salt. Earth system models will benefit from this novelty because future predictions of the climate will become more reliable.

Original article
Hofmann, M., and M. A. Morales Maqueda (2006), Performance of a second-order moments advection scheme in an Ocean General Circulation Model, J. Geophys. Res., 111, C05006, doi:10.1029/2005JC003279.
Please see: http://www.agu.org/pubs/current/jc/

For further information please contact
Matthias Hofmann, Potsdam Institute for Climate Impact Research (PIK)
phone:+49 (0)331 2882567, fax: +49 (0)331 2882600
mobile/cell phone: 0049 (0)172 717 88 33,
e-mail: hofmann@pik-potsdam.de

Miguel Angel Morales Maqueda, Proudman Oceanographic Laboratory (POL),
phone:+44 (0)151 7954851, fax: +44 (0)151 7954801,
e-mail: mamm@pol.ac.uk