资源环境科技发展态势分析平台

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 degrees Cday10years(-1) and 0.69day10years(-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.