The premise of this model intercomparison
was to examine how the mesoscale models (being developed and used
today) do in simulating late northern hemisphere summer conditions
at the VL2 landing site. The reason for choosing VL2 was becuase
there is data to compare the model results with, allowing some
qualification of model performance. Three modeling groups have
submitted results for this simulation. Links to these results
are provided after a brief description of the parameters which
defined the experiment.
The simulations were to be performed using a VERY large (semi-global) polar stereographic mother domain. The following is an image showing the extent to which this type of mother domain covers the planet. The image shows model topography.
Using a mother domain like that above, each modeling group was to "zoom in" towards very high resolution (down to ~5 km grid spacing) at VL2 using nests. An example of how these nests might be configured is shown in the next image. The image shows how the OSU MMM5 was configured for these experiments. Topography of the first nest (the second domain at 54 km) is shown, and the boundaries of the third (18 km) and fourth domains (6 km) are shown with black lines (the color map for topography is not the same as above).
DATA
REQUIRED FOR COMPARISON:
Participating mesoscale modeling groups were asked to produce
model results for the following basic meteorological variables:
surface pressure, U and V wind components at 1.6 m and model air
temperature at 1.6 m. The hope was that each group would be able
to run their model using a prognostic layer which had its center
fairly close to the 1.6 m level of the VL2 instruments. This of
course requires VERY short timesteps with nonhydrostatic models.
At the time of this writing we do not know the heights of the
MRAMS or MMM5. In attempt to make things as uniform as possible
we were all to use a globally uniform visible optical depth of
0.4 for dust and a model top near 0.03 mbar.
The results for each of the three groups are shown on the following three pages:
The OSU Mars MM5 (Tyler and Barnes)
The Mars MM5 of Toigo and Richardson
Results from a 2-D simulation submitted by Tero Siili
In preparing the data for these pages I decided to also show a figure which compares one day of surface pressure results from each of the models against the average cycles of VL2 data that I prepared for this intercomparison. Until recently the OSU MMM5 has been run as a hydrostatic model. In the last few months we have been experimenting with the nonhydrostatic version and for this intercomparison we performed both hydrostatic and nonhydrostatic simulations.
Upon first inspection of our results we were concerned that there was a bug in the nonhydrostatic model, simply because our daily pressure cycle was so different from that of the hydrostatic model. When we saw the data from the other models we became curious if maybe there is some explanation for this besides a bug. The image follows. The hydrostatic OSU MMM5 is not typically THIS good at matching the data we have compared it with!