气候变化背景下青藏铁路沿线多年冻土变化特征研究

多年冻土是复杂地气系统的产物, 以升温为特征的气候变化不可避免地对其产生影响. 基于青藏铁路沿线8个天然场地2006-2011年的地温监测资料, 分析了气候变化背景下, 多年冻土升温特征及上限变化规律, 并对低、高温冻土的变化特征进行了对比分析. 结果表明: 2006-2011年监测期间, 铁路沿线多年冻土正在经历明显的升温趋势, 上限附近和15 m深处平均升温率分别为0.015 ℃·a^-1和0.018 ℃·a^-1, 其中, 低温冻土区在上述两个深度处升温均比高温冻土区显著; 多年冻土上限深度也表现出一定的增深趋势, 平均增深速率为4.7 cm·a^-1, 其中, 高温冻土区增深速率大于低温冻土区. 低、高温冻土对气候变化的响应表现出了较大差异. 同时, 受局地因素的影响, 不同区域在升温和上限增深上也存在一定差异.

Variation characteristics of the permafrost along the Qinghai-Tibet Railway under the background of climate change

As the result of the complex earth-atmosphere exchange system, permafrost will be inevitably influenced by climate change characterized by temperature rising. Based on ground temperature data from eight ground monitoring sites from 2006 to 2011, variation characteristics of permafrost temperatures and permafrost tables in cold and warm permafrost regions were studied in this paper. It is found that permafrost along the railway has experienced a significant warming. During the observation, the average rising rates of permafrost temperatures at 15-m depth and at permafrost table were 0.018 ℃·a^-1 and 0.015 ℃·a^-1, respectively, and the rising of permafrost temperature at the above two depths in cold permafrost regions was higher than that in warm permafrost regions. Moreover, the depth of permafrost table also showed an increase with a mean rate of 4.7 cm·a^-1. The increase of permafrost table in cold permafrost regions was lower than that in warm permafrost regions. Response to climate change showed a great difference between cold and warm permafrost regions. Meanwhile, influenced by local factors, increases of permafrost temperature and permafrost table also showed some differences in different regions.