• 标题：New permafrost is forming on the exposed bottom of Zonag Lake on the Qinghai-Tibet Plateau.
• 关键词：Exposed bottom;Heat conduction model;Periglacial landscapes;Permafrost aggradation;Qinghai-Tibet Plateau
• 作者：Zhang, Yuxin;Xie, Changwei;Wu, Tonghua;Zhao, Lin;Wu, Jichun;Wu, Xiaodong;Li, Ren;Hu, Guojie;Liu, Guangyue;Wang, Wu;Yang, Guiqian

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Most lakes on the Qinghai-Tibet Plateau have expanded in recent years. Zonag Lake, a critical habitat for Tibetan antelopes in the continuous permafrost zone, burst and overflowed after several years of expansion, resulting in a reduction of approximately 100 km2 in the lake area. Observations have revealed newpermafrost is forming on the exposed bottom, accompanied by various periglacial landscapes. The permafrost aggradation on the exposed bottom is rapid, and the permafrost base reached 4.9 m, 5.4 m, and 5.7 m in the first three years, respectively. In this study, the future changes and influencing factors of recently formed permafrost are simulated using a one-dimensional finite element model of heat flow. The simulated results indicate that the permafrost on the exposed bottom is likely to continue to develop, appearing first quick back slow trend. Besides the surface temperature, the annual amplitude is also an important factor in affecting the aggradation of permafrost. The unidirectional permafrost aggradation in the study area is different from the bidirectional permafrost aggradation on the closed taliks around the Arctic. Additionally, snow cover and vegetation are two important factors influencing the future development of permafrost on the exposed lake bottom.