Major steps in the calibration process

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For precipitation, it is advisable to look for hourly and daily stations with at least 5 and preferably 10 or more years of complete data.
In the current NWSRFS, only daily max/min temperature observations are used to generate historical MAT time series.
Given that temperature is generally less spatially variable than precipitation, fewer temperature stations are required.

Quality control procedures are applied to the station data prior to the derivation of time series of mean areal values of the variable.
These procedures are necessary to avoid having a bias between one period of the calibration record and another.
The main quality control procedure for precipitation, temperature and potential evaporation data is to check the consistency of a station using double mass analysis.
Inconsistencies appear as long term shifts in the general slope of the station accumulation curve.

The SAC-SMA requires evapotranspiration demand (ET Demand) as input.
ET Demand is the evaporation that occurs given that moisture is not limiting and considering both the type and activity of vegetation.