Advances in Earth Science ›› 2021, Vol. 36 ›› Issue (9): 962-979. doi: 10.11867/j.issn.1001-8166.2021.081

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Differences of Surface Energy and Shallow Soil Temperature and Humidity at Sunny and Shady Slopes in Permafrost Region Beiluhe Basin Qinghai-Tibet Plateau

Aiyu LAN 1, 2( ),Zhanju LIN 1( ),Xingwen FAN 1, 2,Miaomiao YAO 1, 2   

  1. 1.State Key Laboratory of Frozen Soil Engineering,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China
    2.University of Chinese Academy of Sciences,Beijing 100049,China
  • Received:2021-01-25 Revised:2021-07-10 Online:2021-09-10 Published:2021-10-15
  • Contact: Zhanju LIN E-mail:lanaiyu@nieer.ac.cn;zhanjulin@lzb.ac.cn
  • About author:LAN Aiyu (1995-), Fuan City, Fujian Province, Master student. Research areas include cold region environment and engineering. E-mail: lanaiyu@nieer.ac.cn
  • Supported by:
    the Sub Project of Strategic Leading Science and Technology Project (Class A) of Chinese Academy of Sciences "Three major project decision services"(XDA19070504);The National Natural Science Foundation of China "Quantitative study on local slope aspect effect and water heat difference in high altitude permafrost region"(41971089)

Aiyu LAN, Zhanju LIN, Xingwen FAN, Miaomiao YAO. Differences of Surface Energy and Shallow Soil Temperature and Humidity at Sunny and Shady Slopes in Permafrost Region Beiluhe Basin Qinghai-Tibet Plateau[J]. Advances in Earth Science, 2021, 36(9): 962-979.

The Qinghai-Tibet Plateau (QTP) has a high altitude and strong solar radiation so that the resulting slope effect is significant. The slope effect not only leads to the heterogenous spatial distribution of permafrost, but seriously affects the stability of permafrost subgrade as well. Although there are many reports on the thermal effects between shady and sunny slopes, the quantitative, multi-factor coupled effect studies are still rare, especially in quantitative evaluation with multiple repeated measurements on QTP. Based on the analysis of near surface temperature, humidity, radiation and wind speed in the past four years (2016.09-2020.05) at two sloping sites with opposing aspect in the Beiluhe Basin, the influence of shady-sunny slope effect on near surface water, heat and energy balance were studied in detail. The results show that the underlying surface properties (e.g., radiation, temperature and humidity, soil texture, etc.) on shady and sunny slopes have great differences under the long-term influence of slope aspect. The soil quality on sunny slope is relatively rough, and is not conducive to the maintenance of water, while shady slope is just the opposite. The daily freeze-thaw cycles on sunny slope (south facing slope) at 0.05 m depth were significantly higher than those at shady slope (north facing slope). In 2016 to 2019, the numbers of daily freeze-thaw cycles on sunny and shady slopes were 368 and 109, respectively, and the difference is significant. The soil temperatures at all depth on the sunny slope was significantly higher than those on the shady slope, reaching a temperature difference of about 1.4 ℃. The response of shallow ground temperature to surface heat variation is rapid. However the response rate of shady slope gradually lags behind that of sunny slope with the increase of depth, and this phenomenon is more significant in the warm season. In the thawing stage, the change rate of soil moisture on sunny slope was faster, and the change amplitude was larger with depth, but the soil moisture was significantly lower than that on the shady slope. The differences of surface properties (e.g., surface temperature, humidity, albedo and wind speed) control the exchange process of surface energy, with the result that the soil heat flux and short wave radiation on sunny slope are higher than that on shady slope. This study is of great significance for further understanding the relationship between climate and permafrost in high-altitude, sloping permafrost regions and optimizing the boundary conditions of permafrost simulation.

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