Correlation models of site evaluation on heat factors in the interface layer of northern mountain areas in Hebei Province

To raise the quantitative level of site evaluation,heat factors in the interface layer,including direct solar radiation,air temperature and soil temperature at hill top,south-facing and north-facing slopes,were observed at Xiaobazi Township of Fengning County in Hebei Province during the growing seasons in 2005 and 2006.Correlation models of these factors were obtained by mathematic regression analysis method on the level of significance.The results showed that under the extremely significant level,at the above three observation sites,the variations of direct solar radiation and air temperature were quadratic form,while the variations of air temperature and soil temperature were linear.All of these establish a base for the quantification of site evaluation and fulfil the calculation between each other among heat factors.