Characteristics of Water‐Heat Exchanges and Inconsistent Surface Temperature Changes at an Elevational Permafrost Site on the Qinghai‐Tibet Plateau

Abstract

Increase of surface temperatures has long been recognized as an unequivocal response to radiative forcing and one of the most important implications for global warming. However, it remains unclear whether the variation of ground surface temperature (GST) and soil temperatures is consistent with simultaneous changes of the near‐surface air and land (or skin) surface temperatures (Ta and LST). In this study, a seven‐year continuous observation of GST, Ta, and surface water and heat exchange was carried out at an elevational permafrost site at Chalaping, northeastern Qinghai‐Tibet Plateau. Results showed a distinct retarding of warming on the ground surface and subsurface under the presence of dense vegetation and moist peat substrates. Mean annual Ta and LST increased at noteworthy rates of 0.22 and 0.32 °C/a, respectively, while mean annual GST increased only at a rate of 0.057 °C/a. No obvious trends were detected for the four radiation budgets except the soil heat flux (G), which significantly increased at a rate of 0.29 W · m−2 · a−1, presumably inducing the melting of ground ice and resulted in much higher moisture content through the summers of 2015 and 2016 than preceding years and subsequent 2017 at the depths between 80 and 120 cm. However, no noticeable immediate variations of soil temperatures occurred owing to the large latent heat effect (thermal inertia) and the extending zero‐curtain period. We suggest that a better protected eco‐environment, particularly the surface vegetation, helps preserving the underlying permafrost, and thus to mitigates the potential degradation of elevational permafrost on the Qinghai‐Tibet Plateau.

Mapping Frozen Ground in the Qilian Mountains in 2004–2019 Using Google Earth Engine Cloud Computing

“…The insulating effects of snow cover in the winter and vegetation cover in the summer cause a large temperature deviation between ground surface temperature and the near-surface or land surface temperatures. However, previous studies demonstrated that the near-surface air temperature is linearly correlated to the land surface temperature [73,74]. Moreover, the mean annual or freezing and thawing indices of the near-surface are approximately consistent with those of the land surface on the TP [74].…”

Elevation‐dependent thermal regime and dynamics of frozen ground in the Bayan Har Mountains, northeastern Qinghai‐Tibet Plateau, southwest China

“…In this sense, surface characteristics, rather than elevation gradients, are presumed to be primarily associated with the degree of permafrost warming. Detailed studies comparing the changes of different surface temperatures and their effects on the thermal regime of the ground in the context of climate warming are expected in the future …”

Profile distributions of soil organic carbon fractions in a permafrost region of the Qinghai–Tibet Plateau

“…Based on data for 1957-2016, this area had a mean annual air temperature of −3.5 C. 39 Mean annual precipitation was~460 mm during 2011-2016. 39 The permafrost is warm (with mean annual ground temperature [MAGT] of −0.7 C) and thermally unstable, and discontinuous and sporadic in areal extent. 39 Three representative vegetation types (i.e., ASM, AM, and AS) were selected for study in this area.…”

“…39 The permafrost is warm (with mean annual ground temperature [MAGT] of −0.7 C) and thermally unstable, and discontinuous and sporadic in areal extent. 39 Three representative vegetation types (i.e., ASM, AM, and AS) were selected for study in this area. These three vegetation types are common, representative, and widespread on the QTP.…”