CALIBRATION OF THOM?S FORMULA TO ESTIMATE THE ACCUMULATED DEGREE-DAYS WITH RESPECT TO A THRESHOLD TEMPERATURE

Abstract

The accumulation of heat or cold with respect to the monthly average of the mean temperature and its standard deviation, can be estimated with the Thom?s formula. An additional empirical relationship that Thom?s formula requires is presented in this paper, as well as the proposed correction of this formula in order to get reliable monthly and yearly estimations with respect to the experimental values, which were obtained from the monthly summaries of average temperatures of 15 meteorological stations with data periods ranging from 14 to 59 years, located in the north-central zone of México. Furthermore, two constrasts between the measurements resulting from thermograms and the estimations carried out with the corrected and calibrated Thom?s formula are presented, that verify its usefulness.