Table 2.

List of GRA sites used in this study

Purpose	Dataset	Site	Long, Lat	Site year	Remark
Model training	FLUXNET1	AT_Neu	11.3175, 47.1167	2002–2012	Site-month samples were randomly split into 80% for training and 20% for testing
		DE-Gri	13.5126, 50.9500	2004–2014
		GL-ZaH	-20.5503, 74.4733	2000–2014
		IT-MBo	11.0458, 46.0147	2003–2013
		RU-Sam	126.4958, 72.3738	2002–2014
		US-Var	-120.9508, 38.4133	2000–2014
		CN-Cng	123.5092, 44.5934	2007–2010
	ChinaFLUX	Damxung	91.066, 30.497	2004–2008
		Xilingol	116.40, 43.325	2004–2006
Independent validation in China sites	ChinaFLUX	Damxung	91.066, 30.497	2009–2010	-
		Xilingol	116.40, 43.325	2007–2008
Independent validation across global sites	FLUXNET2	AU-Dap	131.3181, -14.0633	2007–2013	Time spans are less than 10 years; therefore, these sites were used to validate model generalization across more sites.
		CH-Cha	8.4104, 47.2102	2005–2014
		CH-Fru	8.5378, 47.1158	2005–2014
		CH-Oe1	7.7319, 47.2858	2002–2008
		CZ-BK2	18.5429, 49.4944	2006–2012
		IT-Tor	7.5781, 45.8444	2008–2014
		NL-Hor	5.0713, 52.2403	2005–2011
		US-IB2	-88.241, 41.8406	2004–2011
		US-SRG	-110.8277, 31.7894	2008–2014