寒区在变热：暨述张廷军教授四十余载学术之路及贡献

This paper systematically reviews the significant contributions of Professor Zhang Tingjun in his 40 years’academic research career，with the principal framework of climate and frozen soil changes in cold regions and their impacts. The selected publications mainly represent innovative achievements in the following four themes. （i）He investigated permafrost and ground ice distribution in the Northern Hemisphere，including Alaskan Arctic and high mountains in west China. He led the papers（in 1999 and 2000）that estimated permafrost area and ground ice volume based on the map compiled by the International Permafrost Association，which are widely recognized and cited. （ii）He explored the physical basis of the changing frozen ground，snow cover，and other related climate elements in cold regions to reveal potential interactions of key elements of the land surface processes. He synthetically summarized the impacts and physics of seasonal snow cover on frozen ground，which provides an essential start for the research on this topic. （iii）He made efforts to develop，improve，and apply numerical models that capture critical physical processes in frozen soils. His pioneering works on permafrost numerical modeling were beneficial，effective，and operational experiences for large-scale simulations of permafrost dynamics，beyond empirical and semi-empirical methods prior. （iv）He also established cryospheric remote sensing methods for detecting freeze-thaw cycles and seasonal snow cover. Many of these achievements have greatly improved the understanding of the physical basis of the changing cold regions and thus became classic literatures in the research of frozen ground and climate change. His 40-year life of pursuing truth is also worth learning and memorizing.