Glacier surges in the north-west West Kunlun Shan inferred from 1972 to 2017 Landsat imagery

Abstract

The West Kunlun Shan lie close to, or are perhaps part of, two significant glaciological phenomena – the High Mountain Asia surge ‘supercluster’ and the Karakoram Anomaly. However, glaciological studies, and particularly surge studies, in the range are limited. Here, we extend the database of known surges in the region using Landsat imagery and cross-correlation feature tracking. We examine 88 glaciers larger than 1 km2in the Hotan Prefecture of Xinjiang, China, and find evidence of nine surges occurring between 1972 and 2017. Glaciers display low active phase velocities (~0.2–1.5 km a−1) that show seasonal acceleration in the summer, active phase periods as short as 2 years, and build-up and deceleration phases of months--years. Although these observations display characteristics indicative of both the classic hydrological and thermal switch mechanisms, the surging observed displays a close resemblance to that in the adjacent Karakoram ranges. Furthermore, the majority of the surges occur clustered at the end of a decadal-scale warming period, corroborating previously proposed causal links between climate and surging in the Karakoram. We suggest that the two regions should be considered part of one larger system when considering surge dynamics in High Mountain Asia.

Manifestations and mechanisms of the Karakoram glacier Anomaly

“…Many terminus advances and changes in velocity may also be ascribed to glacier surges. The phenomenon is uncommon elsewhere in High Mountain Asia but is widespread in the Karakoram 16 and the nearby regions 31,39,40 . It has been suggested that this clustering of surge-type glaciers might be related to particular climatic and geometric conditions that lead to periodic enthalpy imbalances 18 , but the specific controls on surging remain unclear.…”

“…This is also because data on englacial and subglacial conditions, understood to be pivotal in controlling surge cycles (Box 2), are lacking almost entirely 16 . The frequency of surge events seems to have increased in recent decades 20 , potentially correlating with a period of warming atmospheric temperatures 40 and increasing precipitations 20 . No definitive connection between surge activity and changes in external forcing has however been established yet 41 , and it is still difficult to discern whether the reported increase in surge frequency is related to a real environmental trend, or to an improved ability to detect surges through advances in observational techniques.…”

Characterizing the surge behavior of Alakesayi Glacier in the West Kunlun Shan, Northwestern Tibetan Plateau, from remote-sensing data between 2013 and 2018

“…High Mountain Asia (HMA) hosts the largest glacier concentration outside the polar regions. In HMA, some glaciers surging in the Karakoram and West Kunlun regions have been identified by satellite remote sensing (Copland and others, 2011; Yasuda and Furuya, 2013, 2015; Quincey and others, 2015; Bhambri and others, 2017; Usman and Furuya, 2018; Chudley and Willis, 2019), but comprehensive study of surge behaviors in this area is still limited. In this letter, by utilizing remote-sensing data, we are able to estimate and present the changes in surface velocity, terminus, morphological features and glacier thickness of Alakesayi Glacier during its recent surge and thus expand the knowledge of Alakesayi Glacier surge dynamics.…”

Long-Term Deceleration of Glaciers in the Eastern Nyainqentanglha Mountains, Southeastern Tibetan Plateau, Revealed from Landsat Images

“…After correlating all the selected image pairs, we first identified and removed mismatches or outliers by setting a threshold of signal-to-noise ratio (SNR), which is the ratio between the correlation maximum and the average value in the search window [36]. We chose a threshold of 5 to ensure that most of the suspicious matches could be eliminated while the more reliable estimates were reserved [22,37]. Then, all the velocity fields in the same periods were merged using a median filter both in a spatial and temporal neighborhood, for each x and y component of the velocity.…”