In an ResSim watershed, at least one meteorological station must be defined to model water temperature. The ResSim water quality model allows the user to define multiple meteorological stations. Each meteorological station must include the following weather parameters: atmospheric pressure, air temperature, humidity, shortwave radiation, cloudiness, and wind speed.
If local meteorology varies significantly within the model domain or if the modeled system is large, it is necessary to use multiple meteorological datasets. The Meteorological Dataset Editor allows the user to identify a group of meteorological stations and specify the weather parameters measured at each station. In an ResSim water quality model, the meteorological dataset is linked to the geometry dataset (via the Geometry Editor) to assign each reach and reservoir to a meteorological station. Each water quality cell, defined in the geometry dataset, is individually assigned to a specific meteorological dataset.
A time series of measured solar radiation is now required. However, if this data is not available, it may be computed based on the site's longitude and latitude, Dust Coefficient, and Long/Lat computational Interval. To perform this calculation, the station’s latitude, longitude, and standard meridian (entered in the Station Editor) are needed. Additionally, if the meteorological station is located near the river, the longitude and latitude should correspond to the station’s exact location. If the station is remote, or if weather data is compiled from multiple sources, a central latitude and longitude should be used.
If a time series of atmospheric pressure is unavailable, it can be estimated based on the site’s elevation. Although a time series of atmospheric pressure is preferred, if not available, local atmospheric pressure can be estimated from the site’s elevation provided for a meteorological station. The reference elevation should reflect the average land surface elevation, which can be set in the Watershed Setup module from the Station Editor (Define a Water Quality Station).