Attribute parameter characterized the seasonal variation of gross primary productivity (αGPP): Spatiotemporal variation and influencing factors.

• α GPP , integrated index of GPP seasonality, was ratio of mean to maximum daily GPP. • α GPP in Northern Hemisphere ranged from 0.47 to 0.85 with an average of 0.62. • α GPP decreased as latitude increased, and was stable between years. • Spatial pattern of astronomical radiation seasonality affected that of α GPP. • Spatiotemporal variation of α GPP provided a new approach to assess annual GPP. The seasonal dynamic of gross primary productivity (GPP) has influences on the annual GPP (AGPP) of the terrestrial ecosystem. However, the spatiotemporal variation of the seasonal dynamic of GPP and its effects on spatial and temporal variations of AGPP are still poorly addressed. In this study, we developed a parameter, α GPP , defined as the ratio of mean daily GPP (GPP mean) to the maximum daily GPP (GPP max) during the growing season, to analyze the seasonal dynamic of GPP based on Weibull function. The α GPP was a comprehensive parameter characterizing the shape, scale, and location of the seasonal dynamic curve of GPP. We calculated α GPP based on the data of GPP for 942 site-years from 115 flux sites in the Northern Hemisphere, and analyzed the spatiotemporal variation and influencing factors of the α GPP. We found that the α GPP of terrestrial ecosystems in the Northern Hemisphere ranged from 0.47 to 0.85, with an average of 0.62 ± 0.06. The α GPP varied significantly both among different climatic zones and different ecosystem types. The α GPP was stable on the interannual scale, while decreased as latitude increased, which was consistent across different ecosystem types. The spatial pattern of the seasonal dynamic of astronomical radiation was the dominating factor of the spatial pattern of α GPP , that was, the spatial pattern of the seasonal dynamic of astronomical radiation determined that of the seasonal dynamic of GPP by controlling that of seasonal dynamics of total radiation and temperature. In addition, we assessed the spatial variation of AGPP preliminarily based on α GPP and other seasonal dynamic parameters of GPP, indicating that the understanding of the spatiotemporal variation of α GPP could provide a new approach for studying the spatial and temporal variations of AGPP and estimating AGPP based on the seasonal dynamic of GPP. [ABSTRACT FROM AUTHOR]