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

Abstract

Spin‐up is essential to provide initial conditions for land surface models (LSM) when they cannot be given reliably as in the application to regional permafrost change studies. In this study, the impacts of spin‐up strategy including total spin‐up length and cycling scheme on modeling of permafrost dynamics on the Qinghai‐Tibet Plateau (QTP) were evaluated through two groups of experiments using a modified Noah LSM. The first group aims to test different total spin‐up lengths and the second group for different cycling schemes. The results show that the presence of permafrost prolongs the convergence of the model. Vertically, the slowest convergence is observed at the permafrost table. The insufficiency of total spin‐up length is prone to underestimate permafrost area and overestimate the degradation rate. Different cycling schemes considerably affect the resulting initial thermal fields and result in degradation rates with a difference of 3.37 × 103 km2/a on the QTP, which exceeds the difference (2.92 × 103 km2/a) in the degradation rates reported in existing studies. The multi‐year cycling scheme is generally preferred, but overlong cycle length should be avoided to prevent the introduction of climate change trends in the spin‐up period. We recommend a spin‐up strategy of a 500‐year cycling with the first 5‐ to 10‐year of forcing for modeling permafrost on the QTP with the Noah LSM. Our findings highlight the importance of the spin‐up strategy, which is usually neglected in present LSM‐based permafrost modeling studies.

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

“…The details of the modeling procedure have been presented in our recent publications (G. Zhang et al., 2019; G. Zhang, Nan, Yin, & Zhao, 2021). Based on the high‐performance computing cluster, permafrost dynamics in the historical (1986–2015) and future (2016–2100) periods were simulated by the modified Noah LSM after a 500‐year spin‐up simulation by repeating the 1979–1985 forcing data on each cell to diminish the effects of initial conditions (Ji et al., 2022). The temporal and spatial resolution of the future simulation results is 3 hr and 0.1°, respectively.…”

Bare Patches Created by Plateau Pikas Contribute to Warming Permafrost on the Tibet Plateau

“…The model outputs during 2015–2018 were chosen for analysis, aligning with the timeframe of the UAV and in situ data. Prior to the start of the model run, a 300‐year spin‐up using the repeat forcing from 1979 to 1984 was conducted to mitigate the effects of initial values (Ji et al., 2022). The model was calibrated and validated using in situ soil temperature and moisture records from four permafrost monitoring sites (Figure 1b).…”

Evaluation of Parameterization Schemes for Matric Potential in Frozen Soil in Land Surface Models: A Modeling Perspective

“…Before the formal simulation, each model simulation was subjected to an individual “spin up” period of three decades by repeating the forcing data from 2008 to 2010. This process was necessary to minimize the uncertainties caused by inaccurate initial conditions of soil temperature and moisture (Ji et al., 2022).…”