 |
LandscapeDNDC 1.37.0
|
|
LandscapeDNDC 1.37.0
|
The airchemistry input provides atmospheric trace gas concentrations and atmospheric nitrogen deposition. Nitrogen deposition is consumed by Airchemistrydndc (see Nitrogen deposition over the canopy).
Each item can be given as a constant in the attributes section (used as average/default value) and/or as a time series column in the data section. Column names are case sensitive and must match the names below exactly. Columns with unknown names (e.g. ndry or n) are ignored silently.
| Name | Description | Unit | Default |
|---|---|---|---|
| ch4 | methane concentration | ppm | 0.0 |
| co2 | carbon dioxide concentration | ppm | 370.0 |
| nh3 | ammonia concentration | ppm | 0.0 |
| no | nitric oxide concentration | ppm | 0.0 |
| no2 | nitrogen dioxide concentration | ppm | 0.0 |
| o2 | oxygen concentration | m3 m-3 | 0.208 |
| o3 | ozone concentration | ppm | 0.0 |
| radon | radon activity | Bq m-3 | 0.0 |
| nh4 | ammonium in precipitation (wet dep.) | g N m-3 precipitation (= mg N l-1) | 0.0 |
| no3 | nitrate in precipitation (wet dep.) | g N m-3 precipitation (= mg N l-1) | 0.0 |
| nh4dry | ammonium dry deposition flux | g N m-2 d-1 | 0.0 |
| no3dry | nitrate dry deposition flux | g N m-2 d-1 | 0.0 |
The units are defined in RECORD_ITEM_UNITS (crabmeat: scientific/airchemistry/airchemistrytypes.cpp).
Wet deposition is given as the N concentration in rain water. The deposited amount therefore scales with precipitation of the current time step \( P \) [mm]:
\[ D^{\text{wet}}_X\;[\text{kg N m}^{-2}] = c_X\;[\text{g N m}^{-3}] \cdot P\;[\text{mm}] \cdot 10^{-3}\;[\text{m mm}^{-1}] \cdot 10^{-3}\;[\text{kg g}^{-1}] \]
Dry deposition is given as a daily flux and is independent of precipitation. It is distributed evenly over all sub-daily time steps (time resolution \( r \) [time steps per day]):
\[ D^{\text{dry}}_X\;[\text{kg N m}^{-2}] = \frac{F_X\;[\text{g N m}^{-2}\,\text{d}^{-1}]}{r} \cdot 10^{-3}\;[\text{kg g}^{-1}] \]
Total deposition of a site can thus be prescribed independently of the climate input by putting all deposition into nh4dry and no3dry.
Frequently used conversions to the required dry deposition unit g N m-2 d-1:
| Given as | Conversion to g N m-2 d-1 |
|---|---|
| kg N ha-1 yr-1 | x / 10 / 365 |
| g N m-2 yr-1 | x / 365 |
| mg N m-2 yr-1 (= kg N km-2 yr-1) | x / 1000 / 365 |
| mg N m-2 d-1 | x / 1000 |
For example, 18 kg N ha-1 yr-1 split equally into NH4 and NO3 gives nh4dry = no3dry = 18 / 2 / 10 / 365 = 0.002466 g N m-2 d-1. As a plausibility check, 1 g N m-2 d-1 corresponds to 3650 kg N ha-1 yr-1.
The time stamp of the first record and the record resolution are given by time in the global section, written as YYYY-MM-DD/r with r records per day:
time = "2000-01-01/1" : one record per day (daily data)time = "2000-01-01/24": 24 records per day (hourly data)The resolution must be given explicitly. Otherwise, missing parts of time would be taken from the simulation schedule and the records would be misinterpreted (e.g., with schedule "2003-01-01/24", daily records would be read as hourly records). Therefore, the simulation terminates with the error "airchemistry input: time resolution not given" if /r is missing, and with the error "airchemistry input: time not given" if time is missing completely.
If the data end before the end of the simulation, the model logs the warning "airchemistry input data ends before end of simulation, values after last data
record are synthesized" and continues with synthesized values. Synthesized values are the averages given in the attributes section, or the defaults listed above if no average is given (i.e. zero deposition for nh4, no3, nh4dry and no3dry). To repeat the given data instead, set endless in the project file:
Constant dry deposition of 18 kg N ha-1 yr-1 (50% NH4, 50% NO3), daily records:
The following airchemistry attributes can be defined (input name [unit]):
1.13.2