Isolating the Contributions of Seasonal Climate Warming to Permafrost Thermal Responses Over the Qinghai‐Tibet Plateau

Abstract

The Qinghai-Tibet Plateau (QTP), the highest plateau in the world with an average elevation of over 4,000 m above sea level (a.s.l.), is characterized by unique topography and geographical location. It is thus known as the "Third Pole." Its thermal and dynamic effects exert profound influence on the regional climate and even the global climate system (Duan & Wu, 2005;Yanai et al., 1992). Many important Asian rivers originate from the QTP, including the Yangtze River, the Yellow River and the Mekong River. It holds the largest ice storage after the polar regions, dubbed as the "Asian Water Tower." It drains a lot of water to rivers and is particularly crucial for water resources on the Asian continent (Immerzeel et al., 2010;Xu et al., 2008;Yao et al., 2019). The QTP covers an area of approximately 2.6 × 10 6 km 2 , half of which is underlain by permafrost and accounts for 75% of alpine permafrost in the Northern Hemisphere (Jin et al., 2000).

Qinghai‐Tibet Plateau Permafrost at Risk in the Late 21st Century

“…Examination of the climate variables shows that this phenomenon is strongly tied to the rapid increase in air temperature over the permafrost regions during this period in these two GCM simulations. It is generally accepted that summer temperature is the most important factor determining the ALT, as the active layer thaws the deepest in summer, but a rapid temperature increase in winter can also exert a significant impact on the ALT (G. Zhang, Nan, Yin, & Zhao, 2021). In addition to air temperature, precipitation is also a non‐negligible factor in modulating ALT, as it can impose a cooling effects on the thermal regime of permafrost, which is more prominent in arid and semi‐arid areas of the QTP (G. Zhang, Nan, Zhao, et al., 2021).…”

“…In our previous studies, we demonstrated a modified Noah LSM capable of modeling permafrost dynamics across the QTP and suitable for investigating permafrost responses to climate change (G. Zhang et al., 2019; G. Zhang, Nan, Yin, & Zhao, 2021; G. Zhang, Nan, Zhao, et al., 2021). It improves permafrost physics and accounts for the specifics of the permafrost environment on the QTP, such as sparse vegetation cover, vertical soil heterogeneity, and impedance of ground ice to water migration (X. Wu et al., 2018).…”

“…In our previous studies, we demonstrated a modified Noah LSM capable of modeling permafrost dynamics across the QTP and suitable for investigating permafrost responses to climate change (G. Zhang et al, 2019;G. Zhang, Nan, Yin, & Zhao, 2021;.…”

On the Spin‐Up Strategy for Spatial Modeling of Permafrost Dynamics: A Case Study on the Qinghai‐Tibet Plateau

“…A steady‐state spin‐up is limited in its assumption that the ground states at a study site are initially in equilibrium with the constant hydroclimatic conditions (Lamontagne‐Hallé et al., 2020). If seasonality is considered, a dynamic equilibrium spin‐up simulation (i.e., driven with seasonally varying meteorological forcing without any yearly changes) is preferred for permafrost modeling (Lawrence et al., 2008; Lee et al., 2014; G. Zhang, Nan, Yin, et al., 2021). However, for larger regions where conditions vary spatially, it becomes even more difficult to select a year with representative atmospheric conditions for both steady‐state and dynamic equilibrium spin‐up approaches.…”

“…A steady-state spin-up is limited in its assumption that the ground states at a study site are initially in equilibrium with the constant hydroclimatic conditions (Lamontagne-Hallé et al, 2020). If seasonality is considered, a dynamic equilibrium spin-up simulation (i.e., driven with seasonally varying meteorological forcing without any yearly changes) is preferred for permafrost modeling (Lawrence et al, 2008;Lee et al, 2014;G. Zhang, Nan, Yin, et al, 2021).…”