The spatial representativity of the annual mean temperature of AMeDAS is investigated using the variogram. In the variogram, the value called as "range" is regarded as the measure of the spatial representativity. It is found that the annual mean temperature have at least the spatial representativity of 50-100km. Also, the objective methods for estimating the spatial representativity are proposed; (1) the distance to adapt the variogram model can be determined by the Lepage test, and (2) "ranges" of a variogram with the nested structure can be detected by applying the nested variogram models. These methods are well functioned although the forms of the variograms are different one another. In addition, the following important findings are obtained; (1) "ranges" of variograms are not affected by the station densities, and (2) the nested structure appears when the study area is enlarged.
