Inconsistency and Correction of Manually Observed Ground Surface Temperatures Over Snow-Covered Regions

Consistent Ground Surface Temperature Climatology Over China: 1956–2022

“…During the soil freezing period, soil ice content ( θ i ) is set as the soil water content minus the unfrozen water content (Equation ). Soil mineral thermal conductivity ( λ m ) was set to 2.92 W m −1 K −1 for the bare ground (Cao, et al, 2019, 2023; Ling & Zhang, 2004). While λ m is variable, our sensitivity experiments indicated that λ m has a minimal influence on the simulated T s at the shallow depth of 0.03 m (not shown).…”

“…(1995): $$${\lambda }_{sn}={\lambda }_{i}{\left(\frac{{\rho }_{sn}}{{\rho }_{i}}\right)}^{1.88}$$$ where λ i is the ice thermal conductivity of 2.2 W m −1 K −1 , ρ i is the ice density of 920 kg m −3 . Static snow density is assumed here and was set to 200 kg m −3 based on the stand‐alone in situ measurements (Cao et al., 2023; Zhong, Zhang, Su, et al., 2021).…”

“…These systems differ in their T s measurement when the ground is covered by snow, T s is taken from the surface of the ground beneath the snow in the automatic system using a platinum resistance sensor. The CMA data sets do not include any correction to account for the change in measurement methodology, leading to the T s records of the CMA being inconsistent (Cao et al., 2023; Liao et al., 2019; Wang et al., 2017).…”

“…A few studies have reported that, at the stations with snow cover, the automatically measured daily T s can be up to about 15°C warmer than the manual measurements, which can be attributed to the snow insulation effects (Cui et al., 2020; Du et al., 2020; Zhang, 2005). However, this issue has either been ignored or inaccurately interpolated as being consistent across T s measurements, and soil climate warming since 2000 has been overestimated over China (Cao et al., 2023; Wang et al., 2018; Zhang et al., 2016). Only very limited studies considered the inconsistency.…”