June 1, 2015—New GDD Equation Available

Today we've added a new GDD equation to the Weather API for what is known as the Modified Standard equation.

Background

In agronomic science, the Standard equation is a simple average method that calculates the GDDs regardless of the temperature. The Modified Standard equation is similar, except that it used to exclude very low and very high temperatures where plants do not grow. The equation resets the min or max temperature to the boundary if it goes beyond the constraint.

Change

We have added the modified equation to the API. We did not add the standard model, but the modified equation can be used as the standard model by setting the boundaries to extreme values (e.g., -100 and 200).

In the API, four query string parameters set the GDD equation and boundaries. Use the following parameters to leverage the Modified equation:

Query String Parameter Description of Value Default Value
gddMethod Use modifiedstandard n/a
baseTemp The Base temperature to subtract from the mean temperature. 10°C (50°F)
maxTempCap The upper boundary of the equation. If the day's max temperature exceeds this value, the value is reset to the boundary for calculating the mean temperature. 30°C (86°F)
minTempCap The lower boundary of the equation. If the day's min temperature falls below this value, the value is reset to the boundary for calculating the mean temperature. 10°C (50°F)