104
ANNE- MARIE T R E G UIER
frequency forcing (thus taking into account wind-forced inertial oscillations and the diurnal cycle). Improving the representation of surface
layers is critical for operational forecast models because many clients
need accurate surface velocities. It is also important in coupled models
for climate prediction.
My personal view is that parameterization of the full mesoscale eddy
spectrum is a hopeless challenge. We can certainly improve on existing
parameterizations. Low-resolution climate models will still be necessary
tools in the future, because (fortunately) many aspects of the long-term
climate response are robust with respect to details of mesoscale eddy effects. On the other hand, growing computer power will help us to resolve
a larger part of the mesocale eddy spectrum in forecast models. It is
therefore very important to improve our knowledge of the sub-mesoscale
dynamics and develop suitable parameterizations. In this respect, it is
quite possible that progress will be easier to achieve in the ocean than
in the atmosphere. Atmospheric climate models resolve a large part of
the synoptic scale eddies and use crude parameterizations of the subgrid
scale dynamics. This is because subgrid scale physics linked to atmospheric moisture (cloud physics, radiation) play a more important role
in climate than purely dynamical subgrid scale effects. Ocean models do
not have this additional level of complexity and may be a more suitable
framework to develop parameterisations for the dynamics, which would
fully take into account the spatial inhomogeneity of the mesoscale eddy
field.
Acknowledgements
I thank Patrice Klein for useful discussions and for pointing out equation (9). Comments from Steve Griffies and GODAE school students
have been very helpful.
References
Alvarez, A. and Tintorb, J. (1998). Topographic stress: importance and parameterization. In Ocean Modeling and Parameterization, volume 516 of NATO Science
series C, pages 327-350. Kluwer Academic Publishers.
Arhan, M., Mercier, H., and Lujtjeharms, J. R. E. (1999). The disparate evolution of
three agulhas rings in the south atlantic ocean. J. Geophys. Res., 104:20987-21005.
Batchelor, G. K. (1969). Computation of the energy spectrum in homogeneous t w e
dimensional turbulence. Phys. Fluids., 12, II:233-238.
Beckmann, A. and Doscher, R. (1997). A method for improved representation of
dense water spreading over topography in geopotential-coordinate models. J. Phys.
Oceanogr., 27:581-591.
ANNE- MARIE T R E G UIER
frequency forcing (thus taking into account wind-forced inertial oscillations and the diurnal cycle). Improving the representation of surface
layers is critical for operational forecast models because many clients
need accurate surface velocities. It is also important in coupled models
for climate prediction.
My personal view is that parameterization of the full mesoscale eddy
spectrum is a hopeless challenge. We can certainly improve on existing
parameterizations. Low-resolution climate models will still be necessary
tools in the future, because (fortunately) many aspects of the long-term
climate response are robust with respect to details of mesoscale eddy effects. On the other hand, growing computer power will help us to resolve
a larger part of the mesocale eddy spectrum in forecast models. It is
therefore very important to improve our knowledge of the sub-mesoscale
dynamics and develop suitable parameterizations. In this respect, it is
quite possible that progress will be easier to achieve in the ocean than
in the atmosphere. Atmospheric climate models resolve a large part of
the synoptic scale eddies and use crude parameterizations of the subgrid
scale dynamics. This is because subgrid scale physics linked to atmospheric moisture (cloud physics, radiation) play a more important role
in climate than purely dynamical subgrid scale effects. Ocean models do
not have this additional level of complexity and may be a more suitable
framework to develop parameterisations for the dynamics, which would
fully take into account the spatial inhomogeneity of the mesoscale eddy
field.
Acknowledgements
I thank Patrice Klein for useful discussions and for pointing out equation (9). Comments from Steve Griffies and GODAE school students
have been very helpful.
References
Alvarez, A. and Tintorb, J. (1998). Topographic stress: importance and parameterization. In Ocean Modeling and Parameterization, volume 516 of NATO Science
series C, pages 327-350. Kluwer Academic Publishers.
Arhan, M., Mercier, H., and Lujtjeharms, J. R. E. (1999). The disparate evolution of
three agulhas rings in the south atlantic ocean. J. Geophys. Res., 104:20987-21005.
Batchelor, G. K. (1969). Computation of the energy spectrum in homogeneous t w e
dimensional turbulence. Phys. Fluids., 12, II:233-238.
Beckmann, A. and Doscher, R. (1997). A method for improved representation of
dense water spreading over topography in geopotential-coordinate models. J. Phys.
Oceanogr., 27:581-591.