Abstract
The seasonal dynamic changes of Tibetan glaciers have seen little prior investigation, despite the increase in geodetic studies of multi-year changes. This study compares seasonal glacier dynamics (“cold” and “warm” seasons) in the ablation zone of Parlung No. 4 Glacier, a temperate glacier in the monsoon-influenced southeastern Tibetan Plateau, by using repeat unpiloted aerial vehicle (UAV) surveys combined with Structure-from-Motion (SfM) photogrammetry and ground stake measurements. Our results showed that the surveyed ablation zone had a mean change of −2.7 m of ice surface elevation during the period of September 2018 to October 2019 but is characterized by significant seasonal cyclic variations with ice surface elevation lifting (+2.0 m) in the cold season (September 2018 to June 2019) but lowering (−4.7 m) in the warm season (June 2019 to October 2019). Over an annual timescale, surface lowering was greatly suppressed by the resupply of ice from the glacier’s accumulation area—the annual emergence velocity compensates for about 55% of surface ablation in our study area. Cold season emergence velocities (3.0 ± 1.2 m) were ~5-times larger than those observed in the warm season (0.6 ± 1.0 m). Distinct spring precipitation patterns may contribute to these distinct seasonal signals. Such seasonal dynamic conditions are possibly critical for different glacier responses to climate change in this region of the Tibetan Plateau, and perhaps further afield.
Highlights
Recent ground-based and large-scale remote sensing studies have revealed that monsoonal glaciers in the southeastern Tibetan Plateau have experienced significant mass loss during the last two decades, exceeding the average for High Mountain Asia [1,2]
Our results showed that the surveyed ablation zone had a mean change of −2.7 m of ice surface elevation during the period of September 2018 to October 2019 but is characterized by significant seasonal cyclic variations with ice surface elevation lifting (+2.0 m) in the cold season (September 2018 to June 2019) but lowering (−4.7 m) in the warm season (June 2019 to October 2019)
Our unpiloted aerial vehicle (UAV)-SfM method employed direct georeferencing using Post-Processed Kinematic (PPK) positioning to produce decimeter-accuracy digital elevation models (DEMs) and orthomosaic products, which allowed the robust detection of ice surface elevation change and movements
Summary
Recent ground-based and large-scale remote sensing studies have revealed that monsoonal glaciers in the southeastern Tibetan Plateau have experienced significant mass loss during the last two decades, exceeding the average for High Mountain Asia [1,2]. Satellite remote sensing products can be used to study cryospheric change across a range of spatial (glacier to global scale) and temporal (days to decades) scales, but these data have historically been limited by their relatively coarse spatial resolution as well as extensive data gaps and restricted image quality. This is especially the case for the southeastern Tibetan Plateau, for which the quality of satellite images is generally poor due to pervasive monsoonal cloud cover
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
