Response of shallow soil temperature to climate change on the Qinghai–Tibetan Plateau

Abstract

Under climate change, soil temperature change remarkably influences regional landscapes, ecosystems, hydrological processes, and other parameters. Based on daily soil temperature data from 56 stations from 1965 to 2014, the spatiotemporal variations in shallow soil temperature (0, 5, 10, 15, and 20 cm) on the Qinghai-Tibetan Plateau (QTP) were investigated. The mean shallow soil temperature decreased obviously with altitude both annually and seasonally, except in winter. Primarily dependent on station latitude, the spatial distribution of winter soil temperature was significantly affected by the snow cover conditions. As the soil depth increased, the soil temperature showed a cooling trend in spring and summer but a warming trend in autumn and winter. In the past 50 years, the shallow soil temperature increased considerably on the QTP both annually and seasonally. The warming rate of soil temperature was greatly dependent on station altitude in winter and dependent on latitude in summer and longitude in autumn. Unlike the increasing air temperature that was contributed mainly by winter, the warming rate of soil temperature in winter at depths of 5, 10, 15, and 20 cm was obviously lower than that in other seasons and air temperature in winter. This occurrence may be caused by relatively less snow cover in winter, which produces a weak insulation effect and further makes the soils more vulnerable to cooling from cold air. For the entire region, the soil temperature variability was strongly correlated with the change in air temperature but weakly correlated with precipitation. Although the warming rate in shallow soil tended to be low (high) at stations with a high amount of precipitation (snow cover), the influence of precipitation (including snow) on shallow soil temperature was limited on the QTP in the past few decades.

Assessing the simulated soil hydrothermal regime of the active layer from the Noah-MP land surface model (v1.1) in the permafrost regions of the Qinghai–Tibet Plateau

“…However, our ensemble simulations showed that the surface albedo is extremely overestimated with respect to both magnitude and duration (Fig. 2), implying an extreme overestimation of snow cover, which is consistent with studies using Noah-MP model (Jiang et al, 2020;Li et al, 2020;Wang et al, 2020) and widely found in other state-of-the-art LSMs (Wei and Dong, 2015) for the QTP. Great efforts to resolve the overestimation of snow cover in LSMs include considering the vegetation effect (Park et al, 2016), the snow cover fraction (Jiang et al, 2020), blowing snow (Xie et al, 2019) and the fresh snow albedo (Wang et al, 2020).…”

“…For one thing, large uncertainties still exist in state-of-the-art LSMs when simulating the soil hydrothermal regime on the QTP (Chen et al, 2019). For instance, 19 LSMs in CMIP5 overestimate snow depth over the QTP (Wei and Dong, 2015), which could result in variations in the soil hydrothermal regime with respect to the aspects of magnitude and vector (cooling or warming) (Zhang, 2005). Moreover, most of the existing LSMs are not originally developed for permafrost regions: many of their soil processes are designed for shallow soil layers (Westermann et al, 2016), but permafrost occurs in the deep soil; moreover, the soil column is often considered to be homogeneous, which cannot represent the stratified soil that is common on the QTP (Yang et al, 2005).…”

Three-Dimensional Dynamic Variations of Ground/Air Surface Temperatures and Their Correlation with Large-Scale Circulation Indexes in Southwest China (1980–2019)

“…In such interactions, although soil temperature is different from air temperature in terms of value, oscillation [5], and variation trend [6], the two parameters are normally closely coupled. Previous research has investigated both the fluctuation of soil temperature at different depths [3,[7][8][9][10] and the relationship between soil temperature and air temperature [11][12][13][14]. However, this study focused on soil temperature measured at a depth of 0 cm, i.e., ground soil temperature (GST), and surface air temperature (SAT) because the difference between GST and SAT (i.e., SATD) is proportional to the surface sensible heat flux [15,16], which has substantial influence on soil microorganisms [17], vegetation [18], and climate [14,19].…”

Spatiotemporal variation characteristics of hourly soil temperature in different layers in the low-latitude plateau of China

“…Soil temperature plays an important role in the physical, biological, and microbiological processes that occur in soil, but it is rarely reported as an indicator of climate change because such data generally have limited spatiotemporal coverage (Qian et al, 2011;Bai et al, 2014;Sviličić et al, 2016;Wang et al, 2020). The structure, function, productivity, and stability of an ecosystem largely depend on the soil temperature regime because soil temperature affects the germination of seedling emergence, early developmental and growth processes, tree species distribution and forest composition, and crop yield by changing the carbon and nutrient cycles, fertility, and productivity of the soil (Linderholm., 2006;Curiel et al, 2007;Kurylyk et al, 2014;Zhang et al, 2016;Hu et al, 2019;Oogathoo et al, 2022).…”