This chapter describes how meteorology information is entered into the program using a Meteorologic Model. The Meteorologic Model is responsible for preparing the boundary conditions that act on the watershed during a simulation. Consequently, a Meteorologic Model may be used with one or more basin models. The model can be configured to represent numerous meteorological processes, including precipitation, temperature, short and longwave radiation, and evapotranspiration. The program provides three options for each type of model process:
- Specified Gage Methods. These methods assign a discrete time-series to a known gage location. The time-series may be historical or hypothetical. Typically for lumped modeling, a single gage is assigned to one or more subbasin elements that provide a representative basin average.
- Gridded Methods. These methods utilize gridded data to allow for semi-distributed modeling. Gridded data inherently contain the spatial and temporal distribution of time-series data that allow for reduced assumptions; this is typically the recommended method when possible. Gridded methods are limited by the availability of data, particularly for models where fine resolution is needed or for older historical events. The availability of gridded data is continually improving as this has been an active area of research and development.
- Interpolated Methods. These methods leverage multiple point gage data to infer a spatial and temporal pattern. The time-series data for point gages that are distributed across the model domain are interpolated to better represent spatial variability. The interpolation is performed based on user-specified controls such as radius of influence. This method combines concepts from the Specified Gage and Gridded methods.