The Diurnal Variation and Development Status of Ecoenvironmental Quality in Hainan, China

According to the sustainable development goals, ecoenvironmental quality (EEQ) assessment has become a key issue in response to global climate change. As a national pilot zone for ecological conservation and the free trade zone with a tropical coastal climate in China, Hainan is expected to present distinctive patterns in the ecoenvironment evolution. In this article, with multisource remote-sensing observations, we generated the long-term remote-sensing ecological index to interpret the spatiotemporal patterns and mechanisms for the diurnal and seasonal ecoenvironment, to detect the interaction between the urbanization and ecoenvironment, and to evaluate the development status of EEQ in Hainan. The results showed contrasting evolution of EEQ in the diurnal cycle, especially in the dry season. The improvement of daytime EEQ was primarily influenced by greenness, accounting for a 25% enhancement. On the other hand, the deterioration of nighttime EEQ was mainly driven by heat, explaining a 44% decline. Climate factors had a more significant impact on the evolution of EEQ compared with human activities’ factors. In addition, the mutual influence between the urbanization and ecoenvironment has been enhanced. Thus, the interaction between the contrasting evolution of EEQ and urbanization leads to the opposite development status of EEQ in the diurnal cycle, especially in urban area. Our findings imply that if the contrasting evolution of the ecoenvironment continues, the diurnal difference of the EEQ may be enhanced. The effective action to balance the diurnal difference is rooted in heat control within the context of urban development.