Difference between near-surface air, land surface and ground surface temperatures and their influences on the frozen ground on the Qinghai-Tibet Plateau

Luo, Dongliang; Jin, Huijun; Marchenko, S. S.; Romanovsky, V. E.

doi:10.1016/j.geoderma.2017.09.037

Cited by 112 publications

(90 citation statements)

References 30 publications

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“…In a general sense, the abrupt rising in T a and LST may induce the increasing of soil temperatures, subsequently resulting in potential degradation of permafrost (e.g., Guo & Wang, ; Wu & Zhang, , ; Zhao et al, ). However, the GST, the upper thermal boundary of permafrost (Luo, Jin, Marchenko, & Romanovsky, ), changed with a small trend (0.057 °C/a, p = 0.06) compared with the rates of T a and LST in this study. This demonstrates inconsistent changing trends between T a , LST, and GST and varied responses of change in permafrost temperatures to different surface temperatures.…”

Section: Discussioncontrasting

confidence: 52%

“…There is a close relationship between soil moisture content and temperatures, especially in the freezing period of the active layer. Figure shows a power function ( θ = a × | T | b ) between soil moisture content and the soil temperatures at the depth of 5 cm from 2011 to 2016, indicating the soil temperature dependence of soil moisture content adopted in many numerical simulations of permafrost (e.g., Luo, Jin, Marchenko, & Romanovsky, ). There were few changes concerning the nonlinear equations and related parameters between soil moisture content and temperatures in the freezing stages but abrupt variations in the thawing stages from year to year.…”

Section: Resultsmentioning

confidence: 99%

“…The increased net shortwave radiation (radiative forcing) was considered to be one of the dominant radiation components inducing the rising of surface temperatures. However, surface temperatures indeed differ in the near‐surface air temperature ( T a ) measured at a screen height of 1.5–2.0 m, the land (or skin) surface temperature ( LST ) on the top of canopy layer, and the ground surface temperature ( GST ) 0–5 cm beneath the surface vegetation (Luo, Jin, Marchenko, & Romanovsky, ). Due to easy of detection, most studies concerning the surface temperature changes were mainly related to T a and LST (e.g., Cai et al, ; Qin et al, ; K. Wang, et al, ).…”

Section: Introductionmentioning

confidence: 99%

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

Luo

Jin

et al. 2018

JGR Atmospheres

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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.

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Section: Discussioncontrasting

confidence: 52%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Luo

Jin

et al. 2018

JGR Atmospheres

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“…The soils are typical of alpine meadow soil and meadow bog soil, with rich fine particles but without or with thin organic horizons overlying the coarse soils. The soil texture with fine‐grained layers and low moisture content results in a relatively small thermal offset due to approximately equivalent thermal conductivities when thawed and frozen …”

Section: Methodsmentioning

confidence: 99%

“…As data for surface characteristics, such as detailed snow properties in the BHM are not readily accessible or reliable, Dirichlet's conditions at the upper boundary were set up with daily ground surface temperature (GST) obtained from the national weather station. In this case, the effects of surface vegetation and snow‐cover could be ignored:

\frac{\partial t}{\partial τ} {|_{y = 0} = GST (τ), \frac{\partial t (τ)}{\partial y}|}_{y = 100} = g

where g is the geothermal gradient at the lower boundary. In situ measurements of ground temperatures were used to validate the numerical simulations.…”

Section: Methodsmentioning

confidence: 99%

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

Luo

Jin

et al. 2018

Permafrost & Periglacial

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To investigate and monitor permafrost in the Bayan Har Mountains (BHM), north‐eastern Qinghai–Tibet Plateau, southwest China, 19 boreholes ranging from 20 to 100 m in depth were drilled along an elevational transect (4,221–4,833 m a.s.l.) from July to September 2010. Measurements from these boreholes demonstrate that ground temperatures at the depth of zero annual amplitude (TZAA) are generally higher than −2.0°C. The lapse rates of TZAA are 4 and 6 °C km−1, and the lower limits of permafrost with TZAA < −1°C are approximately 4,650 and 4,750 m a.s.l. on the northern (near Yeniugou) and southern (near Qingshui'he) slopes, respectively. TZAA changes abruptly within short distances from −0.2 to +1.2°C near the northern lower limits of permafrost and from about +0.5 to +1.5°C near the southern lower limits of permafrost. Thawing and freezing on the ground surface at Qingshui'he (4,413 m a. s. l.) are 13.3 d earlier and 26 d later than that at Chalaping (4,724 m a. s. l.), respectively. The temperature gradient at Qingshui'he is clearly larger than that at Chalaping. The changes of permafrost TZAA ranged from 0.03°C to 0.2°C from 2010 to 2017. A 3.5‐m‐thick permafrost near Qingshui'he was observed to disappear in summer 2013. There is no significant correlation between elevation and permafrost temperature changes in the study area, whereas the changes of very warm (close to 0°C) permafrost seem to be slow in the intermontane basins.

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The impact of land surface temperatures on suprapermafrost groundwater on the central Qinghai‐Tibet Plateau

Huang

Dai

Wang

et al. 2019

Hydrological Processes

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To investigate the influences of land surface temperatures (LSTs) on suprapermafrost groundwater discharge, a river valley was selected in a typical permafrost region of Fenghuoshan (FHS) watershed on the central Qinghai‐Tibet Plateau. We developed a two‐dimensional model to simulate the suprapermafrost groundwater seasonal dynamics controlled by LSTs and the changing trends under a warming climate scenario (3°C/100 year). We calibrated key parameters of our model by the field observations at FHS watershed and analysed the relationship between the different LSTs and the suprapermafrost groundwater discharge dynamics in the active layer. The results show that (a) by changing the permeability of the active layer, the LSTs have a significant effect on the suprapermafrost groundwater discharge. A higher LST causes more suprapermafrost groundwater discharge, resulting in a different discharge pattern and affecting the ability to replenish the nearby river in the permafrost area. (b) Under a warming climate, the most obvious change in the suprapermafrost groundwater occurs in the freeze initiation period (from October to December), and there is a significant increase in the suprapermafrost groundwater discharge rate. This study reveals that the LST has a controlling effect on the seasonal dynamics of shallow groundwater systems in permafrost regions, indicating that the impact of local topography on the suprapermafrost groundwater should not be ignored in suprapermafrost groundwater simulations. Moreover, the warming simulation results demonstrate that the freezing season is the significant transformation period of suprapermafrost groundwater dynamics under future climate change, which can be used to better understand hydrological and ecological process changes in permafrost regions under climate warming.

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Difference between near-surface air, land surface and ground surface temperatures and their influences on the frozen ground on the Qinghai-Tibet Plateau

Cited by 112 publications

References 30 publications

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

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

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

The impact of land surface temperatures on suprapermafrost groundwater on the central Qinghai‐Tibet Plateau

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