Ground-based remote-sensing techniques for diagnosis of the current state and recent evolution of the Monte Perdido Glacier, Spanish Pyrenees

Abstract

This work combines very detailed measurements from terrestrial laser scanner (TLS), ground-based interferometry radar (GB-SAR) and ground-penetrating radar (GPR) to diagnose current conditions and to analyse the recent evolution of the Monte Perdido Glacier in the Spanish Pyrenees from 2011 to 2017. Thus, this is currently one of the best monitored small glacier (<0.5 km2) worldwide. The evolution of the glacier surface was surveyed with a TLS evidencing an important decline of 6.1 ± 0.3 m on average, with ice losses mainly concentrated over 3 years (2012, 2015 and 2017). Ice loss is unevenly distributed throughout the study period, with 10–15 m thinning in some areas while unchanged areas in others. GB-SAR revealed that areas with higher ice losses are those that are currently with no or very low ice motion. In contrast, sectors located beneath the areas with less ice loss are those that still exhibit noticeable ice movement (average 2–4.5 cm d─1 in summer, and annual movement of 9.98 ma─1 from ablation stakes data). GPR informed that ice thickness was generally <30 m, though locally 30–50 m. Glacier thinning is still accelerating and will lead to extinction of the glacier over the next 50 years.

Periglacial environments and frozen ground in the central Pyrenean high mountain area: Ground thermal regime and distribution of landforms and processes

“…This belt coincides with MAAT between 2.5 and −0.5°C, and the 0°C isotherm is found between 2,750 and 2,950 m a.s.l. depending on the massifs considered . Thermal regimes that are dependent on snow cover and frozen soil regimes are dominant at these altitudes.…”

“…The 0°C isotherm varies among the massifs, and has been placed at different altitudes: 2,750 m a.s.l., 2,780–3,000 m a.s.l . and 2,950 m a.s.l …”

“…This is a rocky high mountain environment dominated by the periglacial belt and just 19 small glaciers and ice patches, all of which are located in glacial cirques, all beneath summits of over 3,000 m a.s.l. The four studied massifs still contain active glaciers, four in Maladeta, two in Posets, one in Infierno and one in Monte Perdido …”

“…The study of frozen ground increased with the application of analysis and mapping of geomorphological indicators, ground thermal records, geophysical surveys, permafrost distribution mapping and the creation of empirical models as well as ongoing observations of active periglacial processes . Pyrenean permafrost was included in the permafrost map of the northern hemisphere . In the 21st century periglacial processes are still monitored using geomatic techniques and detailed analysis of the activity and distribution of active rock glaciers and permafrost .…”

“…[20][21][22]27,[29][30][31][32] Pyrenean permafrost was included in the permafrost map of the northern hemisphere. 33 In the 21st century periglacial processes are still monitored using geomatic techniques and detailed analysis of the activity and distribution of active rock glaciers and permafrost. [34][35][36][37][38][39][40][41][42][43][44] Synthetic mapping on a regional scale (1:300,000 36 ) uses permafrost indicators (rock glaciers, gelifluction, ice caves, frost mounds, vertical electric soundings and thermal ground recordings), digital terrain models and modeling of basic parameters (mean annual air temperature [MAAT], aspect, slope) that determine the presence of permafrost using the classification of possible or probable permafrost.…”