Background of the SCM case set up
Below we give a short summary of the methods used to derive the initial profiles and forcings for the RICO precipitating cumulus case.
Large scale forcings
Unlike the BOMEX case, for which accurate large scale forcings were obtained from an
extensive set of observations, we were unable to deduce accurate reasonable forcings from the RICO observations. As an alternative, we used a RACMO HindCast to
get estimates of the large scale forcings. The RACMO (Regional Atmospheric Climate Model)
HindCast is a high-resolution version of the ECMWF model initialized every 24 hours with
the ECMWF analysis at 12 UTC. The simulation was performed for a small domain, consisting of
90 x 92 gridpoints with a resolution of 20km, in which the RICO research area (61.46W, 17.97N) is contained.
We use the obtained large-scale forcings to set up 2 experiments for the Single Column Models (SCM's) based on the undisturbed period from 16 December 2004 to 05 January 2005:
For the composite run we derived the mean subsidence velocity profile and the mean large scale temperature and moisture tendencies due to horizontal advection. It is essentially the same case as the one designed for the LES models so for further details of the background of the set up we refer to the section with the LES model background . We urge the SCM modellers to do at least this composite case.
The case description for the short composite case can be found in Set up short composite run while the the case description for the long run is given in Set up long run. The reason for adding this long run is that mean atmospheric state that comes out as a response of the composite case is not necessarily the same atmospheric state that results from the day to day varying forcings over the 3 week period. The long SCM run is a bit controversial in the sense that we are not sure at this moment whether such a long run will drift away too much, especially in the upper troposphere and stratosphere. So SCM-ers are encouraged to investigate modifications for this case, for instance through nudging of the upper part of the atmosphere.