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.