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冰川冻土 ›› 2018, Vol. 40 ›› Issue (6): 1067-1078.doi: 10.7522/j.issn.1000-0240.2018.0413

• 冰冻圈与全球变化 • 上一篇    下一篇

青藏公路沿线多年冻土区活动层起始冻融时间的时空变化特征和影响因素

刘广岳1,2, 谢昌卫1, 杨淑华1,2   

  1. 1. 中国科学院 西北生态环境资源研究院 冰冻圈科学国家重点实验室 青藏高原冰冻圈观测研究站, 甘肃 兰州 730000;
    2. 中国科学院大学, 北京 100049
  • 收稿日期:2017-08-23 修回日期:2018-06-01 出版日期:2018-12-25 发布日期:2019-01-21
  • 作者简介:刘广岳(1984-),男,河北衡水人,工程师,2009年在中国科学院寒区旱区环境与工程研究所获硕士学位,现为中国科学院西北生态环境资源研究院在职博士研究生,从事冻土变化监测与研究.E-mail:liuguangyue@lzb.ac.cn
  • 基金资助:
    中国科学院战略性先导科技专项(19070501);国家自然科学基金项目(41401086;41671068;41421061);中国科学院重点部署项目(KJZD-EW-G03-02)资助

Spatial and temporal variation characteristics on the onset dates of freezing and thawing of active layer and its influence factors in permafrost regions along the Qinghai-Tibet Highway

LIU Guangyue1,2, XIE Changwei1, YANG Shuhua1,2   

  1. 1. Cryosphere Research Station on Qinghai-Xizang Plateau, State Key Laboratory of Cryospheric Science, 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:2017-08-23 Revised:2018-06-01 Online:2018-12-25 Published:2019-01-21

摘要: 多年冻土区活动层冻融格局对气候系统、能量平衡、水文过程和生态系统有重要的影响,地表冻融时间是反映冻融格局时空变化的重要指标。为了探明多年冻土区活动层起始冻融时间的影响因素和机制,通过对青藏公路沿线8个典型活动层观测场地表起始融化时间(OOT)和起始冻结时间(OOF)进行研究,分析了不同观测场起始冻融时间的时空差异及其影响因素。结果表明:(1)青藏高原多年冻土区活动层起始融化主要发生在4月中下旬,起始冻结主要发生在10月中下旬。OOT的年际变化幅度远大于OOF,每年起始冻结的发生较起始融化更为准时。(2)起始融化发生时的气温普遍比起始冻结发生时高1~4℃。气温对OOT的影响要比对OOF大,其中OOT的变化主要与春季气温有关,冬季气温对其影响不大。(3)植被和土壤水分对OOT和OOF有重要调节作用,土壤含水率越高,植被状况越好,起始融化和冻结的发生时间往往越迟。(4)在起始融化和冻结阶段,厚度较大和持续时间较长的积雪对地温变化有明显的抑制作用,对OOT和OOF有延迟作用。

关键词: 多年冻土, 活动层, 冻融, 青藏高原, 青藏公路

Abstract: The situation of freezing and thawing within the active layer has a vital influence on the climate system, energy balance, hydrological processes and ecological system, and the onset date of freezing and thawing is an important index to describe the spatial and temporal variations of freezing and thawing condition. In order to find out the influence factors and process on onset of freezing and thawing within the active layer, eight typical observation sites in permafrost regions along the Qinghai-Tibet Highway were selected, and their onset date of freezing (OOF) and the onset date of thawing (OOT) at each site are analyzed. The analyses showed that:(1) Within the active layer in permafrost on the Tibetan Plateau, the initial thawing occurs mainly in the middle to late April, and the initial freezing occurs mainly in the middle to late October; the annual variation of OOT is greater than that of OOF, and the freezing of the active layer occurs more regular than thawing. (2) The air temperature when the initial thawing of the active layer occurs is generally 1-4℃ higher than that when the initial freezing occurs; the effect of air temperature at OOT is greater than that at OOF; the variation of OOT is mainly related to the mean air temperature in spring, and barely influenced by the mean air temperature in winter. (3) Vegetation and soil moisture play an important role to OOT and OOF; high soil moisture, as well as nice vegetation, generally delays the onset of freezing and thawing. (4) When the freezing or thawing is about to start, snow cover with great depth or rather long duration obviously inhibits the rising of ground temperature and then delays the OOT and OOF, however, this is an occasional event.

Key words: permafrost, active layer, freezing and thawing, Tibetan Plateau, Qinghai-Tibet Highway

中图分类号: 

  • P642.14