The multi-layer snow model from MCH has been implemented to the official COSMO version. It has already prepared in version 5.09a (new fields, namelist variables) and now the code has been added. The scheme is activated by setting itype_snow = 3. With itype_snow_start an initialization method can be chosen.
See: Changes to the Namelists.
The code is embedded in the existing infrastructure for asynchronous output. If more than 1 IO-processor is available, one processor is automatically used for prefetching only. For a setup with only 1 IO-processor (more a debug config), output and prefetching is done on the same processor. Prefetching starts after calling cdf_launch_prefetching in organize_input by PE 0. Due to problems with MPI, only 1 set of BC is read.
The prefetching of boundary-data only benefits model domains larger than 1000x1000 gridcells.
In order to prevent code duplication some routines for NetCDF-IO have been moved from src_input.f90 to io_utilities.f90.
A new namelist parameter (asynio_prefetch_mem) with default value 8 (GB) is introduced to namelist /RUNCTL/. It determines the available memory on the prefetch-PE and is system dependent.
Limitations:
| Group | Name | Meaning | Default | |
|---|---|---|---|---|
| /RUNCTL/ | asynio_prefetch_mem | NEW | Total memory available for buffers on prefetch PE (in units of GB). | 8 |
| /PHYCTL/ | itype_snow | NEW | Type of snow scheme to use (replaces lmulti_snow
|
1 |
| itype_snow_start | NEW | Type of cold start for SNOWPOLINO (only active for itype_snow=3)
|
2 | |
NONE