A Comparison of Thermal Growing Season Indices for the Northern China during 1961–2015

Table 1

Definition of the start, end, and length of the thermal growing season indices used in this study.

Parameters	Indices	Definition
Start of the growing season	=5 d > 5°C (SI 1)	5-day spell with remaining above 5°C
	>5 d > 5°C (SI 2)	6-day spell with remaining above 5°C
	=5 d > 5°C Fr (SI 3)	5-day spell after the last spring frost with remaining above 5°C
	>5 d > 5°C Fr (SI 4)	6-day spell after the last spring frost with remaining above 5°C
End of the growing season	=5 d < 5°C (EI 1)	5-day spell with remaining below 5°C
	>5 d < 5°C (EI 2)	6-day spell with remaining below 5°C
	10 d < 5°C (EI 3)	10-day running mean of falling below 5°C
	Fr OR = 5 d < 5°C (EI 4)	First autumn/winter frost OR 5-day spell with remaining below 5°C
	Fr OR > 5 d < 5°C (EI 5)	First autumn/winter frost OR 6-day spell with remaining below 5°C
Length of the growing season	=5 d > 5°C | =5 d < 5°C (LI 1)	Start (SI 1), end (EI 1)
	>5 d > 5°C | >5 d < 5°C (LI 2)	Start (SI 2), end (EI 2)
	=5 d > 5°C Fr | 10 d < 5°C (LI 3)	Start (SI 3), end (EI 3)
	>5 d > 5°C Fr | 10 d < 5°C (LI 4)	Start (SI 4), end (EI 3)
	=5 d > 5°C Fr | Fr OR = 5 d < 5°C (LI 5)	Start (SI 3), end (EI 4)
	>5 d > 5°C Fr | Fr OR > 5 d < 5°C (LI 6)	Start (SI 4), end (EI 5)