Permafrost temperatures and thickness on the Qinghai-Tibet Plateau

Wu, Qingbai; Zhang, Tingjun; Liu, Yongzhi

doi:10.1016/j.gloplacha.2010.03.001

Cited by 230 publications

(137 citation statements)

References 12 publications

(15 reference statements)

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“…To simulate permafrost we assume an upward thermal heat flux at the bottom boundary and estimate its value to be 0.14 W m −2 at a depth of 50 m using the average geothermal gradient from the four boreholes (T1-T4) shown in Fig. 3, which is reasonable based on a comparison with the observations (0.02-0.16 W m −2 ) from the interior of the QTP (Wu et al, 2010). The vertical soil column is divided into 39 layers in the model (Fig.…”

Section: Soil Freezing and Thawingmentioning

confidence: 95%

“…A few studies reported that permafrost thawing might reduce river runoff (here, runoff is defined as all liquid water flowing out of the study area), especially on the Qinghai-Tibetan Plateau (QTP) (e.g., Qiu, 2012;Jin et al, 2009). Those studies that include intensive field observations of frozen soils have typically been performed at small spatial scales over short periods (e.g., Cheng and Wu, 2007;Wu et al, 2010). Consequently, regional patterns and long-term trends are not typically captured.…”

Section: Introductionmentioning

confidence: 99%

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Change in frozen soils and its effect on regional hydrology, upper Heihe basin, northeastern Qinghai–Tibetan Plateau

et al. 2018

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Abstract. Frozen ground has an important role in regional hydrological cycles and ecosystems, particularly on the Qinghai-Tibetan Plateau (QTP), which is characterized by high elevations and a dry climate. This study modified a distributed, physically based hydrological model and applied it to simulate long-term changes in frozen ground its the effects on hydrology in the upper Heihe basin, northeastern QTP. The model was validated against data obtained from multiple ground-based observations. Based on model simulations, we analyzed spatiotemporal changes in frozen soils and their effects on hydrology. Our results show that the area with permafrost shrank by 8.8 % (approximately 500 km 2 ), predominantly in areas with elevations between 3500 and 3900 m. The maximum depth of seasonally frozen ground decreased at a rate of approximately 0.032 m decade −1 , and the active layer thickness over the permafrost increased by approximately 0.043 m decade −1 . Runoff increased significantly during the cold season (November-March) due to an increase in liquid soil moisture caused by rising soil temperatures. Areas in which permafrost changed into seasonally frozen ground at high elevations showed especially large increases in runoff. Annual runoff increased due to increased precipitation, the base flow increased due to changes in frozen soils, and the actual evapotranspiration increased significantly due to increased precipitation and soil warming. The groundwater storage showed an increasing trend, indicating that a reduction in permafrost extent enhanced the groundwater recharge.

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Section: Soil Freezing and Thawingmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Change in frozen soils and its effect on regional hydrology, upper Heihe basin, northeastern Qinghai–Tibetan Plateau

et al. 2018

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“…The increasing thickness of the active layer has been indicated by many observations in permafrost regions at high latitudes and altitudes (Brown et al, 2000;Frauenfeld et al, 2004;Zhang et al, 2005;Fyodorov-Davydov et al, 2008;Wu et al, 2010;Zhao et al, 2010;Callaghan et al, 2011;Liu et al, 2014a, b;Stocker et al, 2014). Less research has focused on SFG areas Frauenfeld et al, 2004;Frauenfeld and Zhang, 2011;Wang et al, 2015), although the near-surface soil freezethaw status has been investigated using satellite passive microwave remote sensing (Zhang and Armstrong, 2001;Zhang et al, 2003Zhang et al, , 2004Li et al, 2008;Jin et al, 2015).…”

Section: Introductionmentioning

confidence: 91%

Response of seasonal soil freeze depth to climate change across China

et al. 2017

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Abstract. The response of seasonal soil freeze depth to climate change has repercussions for the surface energy and water balance, ecosystems, the carbon cycle, and soil nutrient exchange. Despite its importance, the response of soil freeze depth to climate change is largely unknown. This study employs the Stefan solution and observations from 845 meteorological stations to investigate the response of variations in soil freeze depth to climate change across China. Observations include daily air temperatures, daily soil temperatures at various depths, mean monthly gridded air temperatures, and the normalized difference vegetation index. Results show that soil freeze depth decreased significantly at a rate of −0.18 ± 0.03 cm yr −1 , resulting in a net decrease of 8.05 ± 1.5 cm over 1967-2012 across China. On the regional scale, soil freeze depth decreases varied between 0.0 and 0.4 cm yr −1 in most parts of China during 1950-2009. By investigating potential climatic and environmental driving factors of soil freeze depth variability, we find that mean annual air temperature and ground surface temperature, air thawing index, ground surface thawing index, and vegetation growth are all negatively associated with soil freeze depth. Changes in snow depth are not correlated with soil freeze depth. Air and ground surface freezing indices are positively correlated with soil freeze depth. Comparing these potential driving factors of soil freeze depth, we find that freezing index and vegetation growth are more strongly correlated with soil freeze depth, while snow depth is not significant. We conclude that air temperature increases are responsible for the decrease in seasonal freeze depth. These results are important for understanding the soil freeze-thaw dynamics and the impacts of soil freeze depth on ecosystem and hydrological process.

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“…Studies of the active layer and permafrost on the QTP have received much recent attention [16][17][18][19][20]. Recent work in the area has shown that, due to global climate warming, the permafrost on the QTP has degraded remarkably, including a rise in permafrost temperature, an increase in the thickness of the active layer, and a decrease in permafrost area [21][22][23][24]. This degradation of permafrost may alter the groundwater table, resulting in more arid soil, and exacerbating desertification [21,25,26].…”

mentioning

confidence: 99%