FDD, freezing degree days; TDD, thawing degree days;F , air frost number which is defined as \(F=\frac{\sqrt{\text{FDD}}}{\sqrt{FDD+\sqrt{\text{TDD}}}}\)(Nelson and Outcalt, 1983, 1987); β , frost angle; Twm and Tcm, mean temperatures of the warmest and coldest months; Tws and Tcs, mean warm and cold season temperatures; Lws and Lcs, length of warm and cold season; and A, annual temperature amplitude.
Table 2 Mean monthly, cold and warm periods, and annual mean energy balance components (W/m2) from January-December 2017.