Regional climate change signals inferred from a borehole temperature profile in Muli, Qilian Mountain, using the Tikhonov method

• Published in: Arctic, Antarctic, and Alpine Research
• Main Authors: Jia Liu, Guanli Jiang, Qingbai Wu, Tingjun Zhang, Siru Gao
• Format: Article in Journal/Newspaper
• Language: English
• Published: Taylor & Francis Group 2020
• Subjects: borehole paleothermometry; geothermal gradient; permafrost; tikhonov regularization; geo; envir; Antarctic and Alpine Research; Arctic
• Online Access: https://doi.org/10.1080/15230430.2020.1801149; https://doaj.org/article/88aa1fdd93dd4e3691ec625ad43518c0

Within the gas hydrate drilling project in the Qilian Mountain permafrost region, a temperature–depth profile measured from borehole DK-12 in Juhugeng of Muri Coalfield, Tianjun County, Qinghai Province, China, was analyzed to infer recent climate changes. The long-term surface temperature and thermal gradient were retrieved from borehole temperature measurements. The ground surface temperature (GST) changes were reconstructed by inversion of transient temperature perturbations through solving an inverse heat conduction problem using the Tikhonov method. Based on the instability of this kind of inverse problem and the nature of method-dependent features of borehole paleothermometry, we initially applied the Tikhonov regularization technique to obtain a stable past GST variation pattern with relatively low resolution. The inversion results showed that this region experienced temperature fluctuation with a total warming of 3°C (±1.6°C) from 1400 to the 2010s and a more exacerbated warming starting from the 1960s. The GST trend fit the surface air temperature observation trend from the nearest Yeniugou meteorological station. This work fills the gap created by limited meteorological records in the Muli area and extends knowledge of ground surface temperature trends going back more than ten centuries.