atm_init
The application atm_init creates an atmospheric data file with initial air parcel positions. The code will generate air parcels in a simple manner with user-defined settings.
# calling atm_init
$ ./atm_init <ctl> <atm_out>
The following specific configuration parameters can be used to determine the release position:
| parameter | purpose | default |
|---|---|---|
| INIT_T0 | Release time range start [s] | 0 |
| INIT_T1 | Release time range end [s] | 0 |
| INIT_DT | Release time interval [s] | 1 |
| INIT_Z0 | Release altitude range start [km] | 0 |
| INIT_Z1 | Release altitude range end [km] | 0 |
| INIT_DZ | Release altitude interval [km] | 1 |
| INIT_LON0 | Release longitude range start | 0 |
| INIT_LON1 | Release longitude range end | 0 |
| INIT_DLON | Release longitude interval | 1 |
| INIT_LAT0 | Release latitude range start | 0 |
| INIT_LAT1 | Release latitude range end | 0 |
| INIT_DLAT | Release latitude interval | 1 |
For the standard longitude/latitude grid these horizontal coordinates
are given in degrees. For the special-purpose UTM-grid mode
(MET_COORD_TYPE = 1), the same parameters refer to UTM easting and
northing in metres. The horizontal spread parameters (INIT_SLON,
INIT_SLAT, INIT_ULON, INIT_ULAT, and INIT_SX) use the same
horizontal coordinate units as the respective met grid: degrees for longitude/latitude grids and
metres for UTM grids.
The following optional parameters can be used for controlling the release of air parcels:
- INIT_REP: This parameter controls the number of air parcels in each release position. The default value is 1.
- INIT_MASS: Total release mass [kg]. The default value is 0.
- INIT_VMR: Volume mixing ratio of each air parcel [ppv]. The default value is 0.
- INIT_ST/INIT_SZ/INIT_SLON/INIT_SLAT: If this parameter is set to non-zero value, the air parcels are released with a Gaussian distribution in time/altitude/longitude/latitude. The parameter value represents the full width at half maximum.
- INIT_UT/INIT_UZ/INIT_ULON/INIT_ULAT: If this parameter is set to non-zero value, the air parcels are released with a uniform distribution in time/altitude/longitude/latitude. The parameter value represents release range.
- INIT_EVENLY: If this parameter is set to 1, the number of air parcels released will be weighted by the cosine of latitude so that the air parcels are evenly distributed globally.
- INIT_RHO: If this parameter is set to 1, air parcels are distributed in altitude according to atmospheric density (Monte Carlo sampling with density-weighted vertical distribution). The surface pressure is taken from the meteo data. Rejected samples below the density threshold (ρ < ρ_min with ρ_min = RHO(1100 hPa, 200 K)) are discarded. Requires meteo data. Default is 0.
- INIT_IDX_OFFSET: Offset value added to air parcel indices. This parameter allows customization of the starting index for air parcels, which can be useful for domain decomposition or when combining multiple initialization runs. The default value is 0.
Note: Instead of using the control file the configuration parameters can also be appended to the function call.