9.0 POST-IMPLEMENTATION CHANGES

Because of problems found in the weeks following this implementation the following changes were made to the system:

1. A convective adjustment was added to the grid-scale precipitation code to remove remaining local static instability not eliminated by the convection scheme. This change has been shown in full-resolution tests to systematically damp tropical vortices. Spurious tropical vortices will still appear, but they will be considerably weaker.

2. A substantial increase was made in the horizontal diffusion for the small-scale end of the spectrum

3. A set of changes was made to reduce (but not eliminate) the warm bias over land:

Changes (1) and (2) were tested in a parallel system at T170 resolution, while the changes in (3) (which are not resolution-dependent) were tested at T62. Then, the entire package was tested in the T170 parallel system from July 17 through July 21.

The map files are labeled in the form [mdd]f[hh].gif, where m=month, d=day, and hh= forecast hour, e.g., 717f12.gif is the 12-h forecast from 17 July. All forecasts originate at 00Z.