Variogram Model > Variogram Theory Models

Spherical Mode

The formula of the Spherical Model is:

Where is the nugget constant, C+ is the Sill, C is the structure variance, and a is the effective range. When =1 and C=1, this model is called Standard Spherical Model. The slope rate at the point of origin is 3C/2a, and the intersection between the Sill value and x-axis is 2a/3. The Spherical Model is the most common model in geostatistics. Its features are that it has a linear growth when the distance between 2 points are short (closer to the point of origin); however, when it passes the range value, it will be a line parallel to the X-axis (its value is ).