Active layer thickness calculation over the Qinghai–Tibet Plateau

The rising air temperature and increased human activities have caused permafrost degradation over the Qinghai–Tibet Plateau, including thickening of the active layer. The active layer plays an important role in cold regions. Active layer thickness (hereafter ALT) variation may have profound socio-economic and eco-environmental consequences. Using a climate-driven model based on Kudryavtsevʹs formulations and data from climate records, snow and vegetation parameters, and soil features, we calculated ALTs of the permafrost regions over the Qinghai–Tibet Plateau. A general agreement was found when comparing the calculated results with measured values at survey sites. A distribution map of ALT over the Qinghai–Tibet Plateau shows that ALTs in the central part of the plateau are generally smaller than those in other regions while ALTs in the northern and western regions are larger than those in the eastern and southern regions of the plateau. ALTs of the permafrost regions along the Qinghai–Tibet Highway are generally larger than 2.0 m. The regions with ALTs less than 2.0 m are mainly in the high-mountain areas.