-
Notifications
You must be signed in to change notification settings - Fork 8
Initial conditions
The initialization of vegetation in the ED2 model requires that the user define, for each polygon, the attributes of the hierarchy of sites, patches, and cohorts. It is usually relatively easy to convert plot census information into vegetation files by assuming each plot corresponds to a patch and each tree in a patch corresponds to a cohort. It may be necessary to break large plots or mapped stands into subplots. The following sections explain the structure on how to build these files. In order to use these files to initialize the model, the user must set IED_INIT_MODE to 3 (in case site level information is available) or 6 (in case it is not).
To restart ED-2.1 from a previous ED-2.1 simulation, the user should set IED_INIT_MODE to either 4 or 5, and the full explanation can be found on the namelist description of IED_INIT_MODE.
The site file is only used when running with IED_INIT_MODE = 3. This file comes in two formats and file format is specified in the file header:
nsites <num></num> file_format <ff></ff>
Both file formats then contain a site attribute header line and then the following site attributes
| Attribute | Unit | Description |
|---|---|---|
| sitenum | Integer | Site number |
| area | proportion | Site fractional area |
| TCI | float | Topography convergence index (Bevin and Kirby 1979) |
| elev | meters | elevation |
| slope | degrees | slope |
| aspect | degrees | Aspect |
| Soil | {1-13} | Soil class (see NSLCON in in ED2IN Namelist) |
For file format #2 there is then an N x (N+1) adjacency matrix that is used in the runoff calculation. For file format 1 the adjacency matrix is approximated based on the proportional abundance of each site and assuming a random distribution of sites. File format #3 is like #1 but a soil class is specified for each soil layer rather than one class for all layers. The adjacency matrix has N+1 columns because the last column is the transition to the water patch.
| Variable | Units | Description |
|---|---|---|
| time | years | Year |
| Site | integer | Site number (only included in where IED_INIT_MODE=3, ) |
| patch | String | Patch identifier (arbitrary, on output the hex memory address of the patch) |
| trk | 0 – non-forest 1 – secondary 2 - primary | Vegetation type/history |
| age | years | Patch age since disturbance |
| area | proportion | Fractional area represented by patch. For format 1 is area in m2 |
| water | m3/m3 ?? | Not actually read |
| fsc | Kg/m2 | Fast soil carbon |
| stsc | Kg/m2 | Structural soil carbon |
| stsl | Kg/m2 | Structural soil lignin |
| ssc | Kg/m2 | Slow soil carbon |
| psc | Kg/m2 | Passive soil carbon (not actually read) |
| msn | Kg/m2 | Mineralized soil N |
| fsn | Kg/m2 | Fast soil N |
| Variable | Unit | Description |
|---|---|---|
| time | year | year |
| patch | string | Unique identifier |
| cohort | string | Unique identifier |
| dbh | cm | Stem diameter breast height |
| hite | m | Tree height |
| pft | integer | Plant Functional Type |
| n | Stem/m2 | Stem density |
| bdead | KgC/plant | Structural carbon |
| balive | KgC/plant | “Live” carbon (leaf, fine root, sapwood) |
| Avgrg | No longer used (was average radial growth) |
There are a number of ways for the user to prescribe the initial soil temperature, and soil moisture content. These are controlled by the ED2IN setting ISTWFLG:
- 0 – Interpolate from the coarser nested grid
- 1 – Read values from file (ISTWFLN)
- 2 – Set values prescribed values
Land cover setting is specified by the ED2IN setting IVEGTFLG. This setting is used only for regional runs, and the idea is to eliminate polygons that would fall over a water body (ocean, lakes, rivers). In case of regional run, the first grid should always have IVEGTFLG set to 1. The standard land cover setting comes from the Olson Global Ecosystem data with roughly 1 km resolution. Even though the data itself contains information on which type of vegetation (or water) exists at each point, all that ED2 uses is the information on whether the point has land or water.
The subroutines that control the land cover mapping are adaptations of the ones available at RAMS and BRAMS.