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
- On 24 June at 1200Z a correction was made to the analysis system to speed
the rate of convergence of the iterations. This is expected to reduce the
level of noise in both the analysis and the forecast]
- Additional changes were made to the system on 1200Z Tues 21 July as follows:
2. A substantial increase was made in the horizontal diffusion for the small-scale end of the
3. A set of changes was made to reduce (but not eliminate) the warm bias over land:
- elimination of short-wave absorption by aerosols
- correction of error in surface albedo
- increase in evaporation from vegetation (thus reducing sensible heating
and increasing latent heating over areas with vegetation)
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.