Noah Modelling of the Permafrost Distribution and Characteristics in the West Kunlun Area, Qinghai‐Tibet Plateau, China

Abstract

AbstractThe Noah land surface model (LSM) can simulate well the hydrological and thermal processes of permafrost in the Qinghai‐Tibet Plateau (QTP) and provides more permafrost metrics than those of statistical empirical models. The aim of this study was to develop a prototype for permafrost modelling by Noah and validate the model with field data. This was accomplished by modifying Noah, introducing a new thermal roughness scheme, a parameter calibration method and extending the simulation depth to allow for soil heterogeneity. The modified Noah LSM was validated using observations from the Tanggula meteorological station. Key permafrost metrics were simulated, including mean annual ground temperature (MAGT) at the depth of zero annual amplitude (DZAA), active layer thickness (ALT) and ground ice content of the West Kunlun area in the QTP. The permafrost distribution of the West Kunlun was mapped using the simulated MAGT and compared to a permafrost distribution map based on field observations. Data from ten boreholes were used for verification. The simulation error of the MAGT is less than 1.0 °C for eight boreholes, and the ALT simulations have relative errors of less than 25 per cent for seven boreholes. The Kappa coefficient for the two maps is 0.70. Permafrost characteristics including the distribution of different permafrost types, DZAA, ALT, MAGT and ground ice content in the West Kunlun are strongly influenced by altitude and the local environment. Such permafrost modelling can be extended to the rest of the QTP. Copyright © 2015 John Wiley & Sons, Ltd.