Abstract
Abstract. In this study, we investigated changes in active layer thickness (ALT) and permafrost temperatures at different depths using data from the permafrost monitoring network along the Qinghai-Xizang (Tibet) Railway (QXR) since 2005. Among these sites, mean ALT is ~3.1 m, with a range of ~1.1 to 5.9 m. From 2006 through 2010, ALT has increased at a rate of ~6.3 cm a−1. The mean rate of permafrost temperature rise at the depth of 6.0 m is ~0.02 °C a−1, estimated by linear regression using 5 yr of data, and the mean rate of mean annual ground temperature (MAGT) rise at a depth of zero amplitude is ~0.012 °C a−1. Changes for colder permafrost (MAGT −1.0 °C). This is consistent with results observed in the Arctic and subarctic.
Highlights
Qinghai-Xizang (Tibet) Plateau (QXP), with an average elevation of more than 4000 m above sea level (a.s.l.), is the highest and the most extensive plateau in the world (Liu and Chen, 2000) and is known as “roof of the world”
This study is complementary to previous studies and contributes to the understanding of the thermal state of permafrost and the active layer on the QXP during the third International Polar Years
In the basins along the QTR, the mean annual ground temperature (MAGT) are higher than −0.5 ◦C, most of the active layer thickness (ALT) is greater than 3 m, permafrost thickness ranges from 10 m to 25 m, and thawed areas are widespread
Summary
Qinghai-Xizang (Tibet) Plateau (QXP), with an average elevation of more than 4000 m above sea level (a.s.l.), is the highest and the most extensive plateau in the world (Liu and Chen, 2000) and is known as “roof of the world”. This study is an additional contribution to the IPA’s IPY project in studying changes in the thermal state of permafrost and active layer thickness (ALT) in the QXP. We investigated changes in soil temperature within the active layer, the permafrost temperature at 6.0 m depth from 1996 to 2006 (Wu and Zhang, 2008), and ALT from 1995 to 2007 (Wu and Zhang, 2010) along the Qinghai-Xizang (Tibet) Highway (QXH). Due to the construction of the Qinghai-Xizang Railway (QXR), most of these study sites were terminated. All of these sites were relatively shallow, usually ∼6–8 m in depth.
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