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The Forcing Manager enables you to create your own specific Full Forcing files. Forcing is a type of Lateral Boundary Condition, in which values from the one dimensional model or forcing file are copied to the border. The Full Forcing allows a forcing of all the pre-defined profiles to the main model, including air temperature, humidity, wind speed and direction, radiation or cloud cover, and precipitation.
The values for the Full Forcing need to be defined in 30 minute intervals and can origin from either measured data or common weather file types.
If you have exact weather data for your simulation area originating from e.g. measurements and would like to use this data to simulate your model in ENVI-met, you can create a *.CSV-file and convert the data to a Full Forcing File. The *.CSV-file needs to follow the formatting specifications given below.
After indicating your CSV settings (separators and heading), deciding whether you would like to force either radiation or cloud coverage, and defining the measurement heights of your data, you can import your data to an ENVI-met Forcing File. Regarding the columns for radiation / cloud coverage: Depending on the data you have, you can either enter the cloud cover for the different height levels (in octas) or the radiation (splitted into shortwave direct, diffuse and longwave radiation). Depending on what you choose, you have to tell the forcing manager how to interpret these columns, as cloud cover or as radiation data.
Common Weather Files
Using input data from local weather files can be a good way to realistically force your simulation boundary conditions. There are many types of weather files available and ENVI-met currently allows the import of *.EPW and *.TRY weather files. The Forcing Manager automatically reads the file format and converts it into a forcing file usable in the simulation process.
Choosing what to force
When preparing a simulation, you need to tell ENVI-met which of the data provided by the full forcing shall be used in the simulation. We only recommend forcing precipitation if you planning to simulate very long periods of time (several months). To learn about precipitation you can click here.
Please check all forced values: Do radiation values look unreasonable to you? Are wind speeds too low (<0.8 m/s) or too high (> 5 m/s). Is the wind direction rapidly and strongly changing between timesteps (e.g. from 0° to 180° within one hour)? Are the relative humidity values too high for your high temperature values, resulting in a very high specific humidity?
Usage of Forcing File
Once created, the Forcing File can then be used as meteorological input data for the simulation run in ENVI_MET. The usage of the file can be defined in the ENVIguide. Here, you can determine which file is to be used and which parameters are to be forced.