A new method for generating the thermal growing degree‐days and season in China during the last century

Abstract

Changes in the thermal variables of growing degree-days (GDDs) and season have substantial effects on vegetation growth and distribution. The magnitude and spatial distribution of changes in GDDs and season in China during the past century are still uncertain, mainly due to limited daily observations before 1950. In this study, a site-specific multiple linear regression method is developed based on the homogenized daily temperature data of 536 meteorological stations in China for 1960-2010, in order to estimate the annual variables of GDDs and season with only monthly temperature. The method is robust for all stations and interannual variability. Since it could accurately simulate the observed values in 2011, with relative errors of −0.02 and 0.96% for GDDs and growing season (GS), respectively. We simulated the thermal variables based on this method using gridded monthly temperature data for 1901-2010. The interannual variations of simulated GDDs and GS matched well with that of observed values from 1960 to 2010, with high correlation coefficients of 0.99 and 0.92, respectively. Overall, the GDDs and season showed significant (p < 0.01) increasing trends of 11.88 ∘ C·day 10 years −1 and 0.69 day 10 years −1 , respectively, in China as a whole, with the trends increasing from 1991 to 2010. Moreover, all eco-geographical zones showed positive trends during 1901-2010. The GS was more prolonged in northern zones, and degree-days were more increased in north-subtropical, south-subtropical, and tropical zones. However, both the GDDs and season have decreased in the part of Southwest China in the mid-subtropical zone over the past century.

Divergent responses of thermal growing degree‐days and season to projected warming over China

“…Based on their positive sensitivities to temperature change, the national average GDD and GS in the long term are 279.1 °C·d higher and 16.5 days longer for RCP 2.6 and 964.4 °C·d higher and 50.3 days longer for RCP 8.5, relative to the present day. Therefore, increases in thermal conditions (GDD and GS) present since the start of the 20th century (Yin et al, ) may persist to the end of the 21st century in China. The advance in SOS projected in this study, which captures the projected advance in SOS derived from NDVI variations under the RCPs (Xia et al, ), is consistent with the predicted earlier spring phenology of the deciduous broadleaf forest in northern China (Luo et al, ).…”

“…There are various base temperatures used for calculating the GDD and GS, among which 10 C is typically used for China (Liu et al, 2010;Yang et al, 2013;Yin et al, 2017a) because forests and crops in many regions of China would grow rapidly if T d remained above 10 C (Huang, 1959).…”

“…There is still no universally accepted method to calculate the GDD and GS (Linderholm, 2006;Qian et al, 2011;Ruosteenoja et al, 2016;Sabziparvar and Jahromi, 2018). Applying a 5-day running mean method (Yin et al, 2017a), which had been tested and widely used for calculating the GDD and GS (Linderholm, 2006;Liu et al, 2010;Yang et al, 2013;Potopová et al, 2015), the T d on a horizontal grid with 0.5 × 0.5 resolution is used to simulate the annual GDD and GS above 10 C.…”

“…As two commonly used indicators for quantifying the relationship between temperature and vegetation growth (Swan et al, 1987;Lobell et al, 2011;Anandhi, 2016), GDD and GS are closely correlated with changes in surface air temperature. Global surface temperature increased by approximately 0.85 C (0.65-1.06 C) between 1880 and 2012 (IPCC, 2013), while GDD has increased and the GS lengthened in some Northern Hemisphere regions since the late 19th century (Skaggs and Baker, 1985;Bootsma, 1994;Carter, 1998;Robeson, 2002;Linderholm et al, 2008;Yin et al, 2017a), with the GDD enhancement and GS extension more evident after the mid-20th century when global warming intensified (Frich et al, 2002;Liu et al, 2010;Barichivich et al, 2012;Blinova and Chmielewski, 2015;Irannezhad and Kløve, 2015;Spinoni et al, 2015;Yin et al, 2017b). Under the representative concentration pathway scenarios (RCPs) used in the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5), the global mean surface temperature during 2081-2100 would be 0.3-4.8 C higher than that during 1986(IPCC, 2013.…”

Changes of heating and cooling degree‐days in Europe from 1981 to 2100

“…The theoretical formulation of heating and cooling (and growing) degree‐days can be performed in different ways, depending on the nature and scope of the study (Thom, ; Schoenau and Kehrig, ). Computation methods range from simple models based on monthly or annual temperature (McMaster and Wilhelm, ; Mourshed, ; Yin et al, ) to more sophisticated parameterizations (Allen, ; Gelegenis, ).…”