4.1 Ground temperature
Geothermal measurements were carried out at the Suntar-Khayata Station site in three boreholes at depths down to 10-20 m in 1958. Temperature measurements were made 4 times a day at depth horizons to a depth of 1 m, once a day to a depth of 5 m and once every five days on deeper horizons. Average monthly ground temperatures at numerous horizons were published in Grave (1959). We used these data to verify ground temperature modeling which was conducted on a daily time step at different depths using thermal-physical soil properties. Mean absolute deviations between simulated and observed monthly temperatures accounted for 1.1 ºС, 0.7 ºС, 0.2 ºС and 0.3 ºС, and their maximum values +3.6 ºС (December), +4.0 ºС (November), +2.4 ºС (June) and -1.7 ºС (January) at 5, 50, 100 and 200 cm depths correspondingly in 1958 (Table 4). Overall, modelled soil temperature values at different depths provide a good fit to the observed values (Fig. 3).