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The coupled model used by the MPI consists of the ECHAM5 atmospheric
general circulation model and the MPI-OM1 ocean general circulation model
coupled with the OASIS coupler (Follow this link
for some information on an extended coupled model run). Preliminary results
from an extended-range integration with the coupled model concerning the
North Atlantic are discussed in Latif et al. (2002). ECHAM5 is the latest
version of the ECHAM model. The main changes from the ECHAM4 model are
in the radiation and cloud schemes, and in the coupling between land surface
and atmosphere. Here, ECHAM5 is run at T42 resolution with 19 vertical
levels. MPI-OM1 is the next generation of the HOPE model (Marsland et
al., 2002). The most significant changes from the previous version (HOPE-E)
are the use of a generalized orthogonal curvilinear C-grid, and the addition
of an improved scheme for slope convection and a Gent and McWilliams style
eddy-induced mixing parameterization (Gent and McWilliams, 1990). The
grid has poles over Greenland and Antarctica. An increased horizontal
resolution is employed between 5S and 5N, with 0.5 and 2.5 degree meridional
and zonal grid spacing, respectively. The model has 23 vertical levels,
with 10 over the upper 300m.
Hindcasts are initialized using a coupled assimilation scheme in which
the model is run in coupled mode up to the start of the hindcast with
SST strongly relaxed to observations. The advantage of this method is
that the model is started with a balanced set of atmospheric and oceanic
initial conditions. Individual ensemble members are generated by choosing
different atmospheric conditions around the hindcast start date.
Gent, P. R. and J. C. McWilliams, 1990. Isopycnal mixing in ocean circulation
models. J. Phys. Ocean., 20,150-155.
Latif, M., E. Roeckner, M. Botzet, M. Esch, H. Haak, S. Hagemann, J.
Jungclaus, S. Legutke, S. Marsland, U. Mikolajewicz, and J. Mitchell,
2004. Reconstructing, Monitoring, and Predicting Multidecadal-Scale Changes
in the North Atlantic Thermohaline Circulation with Sea Surface Temperature.
J. Climate, 17, 1605-1614.
Marsland, S. J., H. Haak, J.H. Jungclaus, M. Latif and F. Röske,
2003. The Max-Planck-Institute global ocean/sea ice model with orthogonal
curvilinear coordinates. Ocean Modelling, 5, 91-127.
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