Insights in a remote cryosphere: A multi method approach to assesspermafrost occurrence at the Qugaqie basin, westernNyainqêntanglha Range, Tibetan Plateau

Abstract. Permafrost as a climate-sensitive parameter, its occurrence and distribution plays an important role in the observation of global warming. However, field-based permafrost distribution data and information on the subsurface ice content at the large area of the southern mountainous Tibetan Plateau (TP) is very sparse. Existing models based on boreholes and remote sensing approaches suggest permafrost probabilities for most of the Tibetan mountain ranges. Field data to validate permafrost models are generally lacking because access of the mountain regions in extreme altitudes is limited. The study provides geomorphological and geophysical field data from a north-orientated high-altitude catchment in the western Nyainqentanglha Range. Our multi-method-approach combines (A) geomorphological mapping data, (B) subsurface ice-occurrence derived from electrical resistivity tomography (ERT) data, and (C) multi-annual displacement rates from Interferometric Synthetic Aperture Radar (InSAR) analysis to assess the lower occurrence of the probable permafrost around 5400 m a.s.l. in the Qugaqie basin. Periglacial landforms such as rockglaciers and protalus ramparts are located in the periglacial zone from 5300–5600 a.s.l. The altitudinal periglacial landform distribution is supported by ERT data detecting ice-rich permafrost in a rockglacier at 5500 m a.s.l. and ice lenses around the rockglacier (5450 m a.s.l.). The highest, multiannual displacement rates up to 150 mm/y are observed typically on these rockglaciers. However, seasonality of rockglacier surface displacement like in other high mountain areas is missing. This study closes the gap of unknown state of periglacial features and potential permafrost occurrence in a high-elevated basin at the western Nyainqentanglha Range (Tibetan Plateau) and suppose – compared to other high mountain regions – a higher-elevated permafrost occurrence.