Factors influencing the ground thermal regime in a mid-latitude glacial cirque (Hoyo Empedrado, Cantabrian Mountains, 2006–2020)

.Air and near-surface ground temperatures were measured using dataloggers over 14 years (2006–2020) in 10 locations at 2262 to 2471 m.a.s.l. in a glacial cirque of the Cantabrian Mountains. These sites exhibit relevant differences in terms of substrate, solar radiation, orientation, and geomorphology. Basal temperature of snow (BTS) measurements and electrical resistivity tomography of the talus slope were also performed. The mean annual near-surface ground temperatures ranged from 5.1 °C on the sunny slope to 0.2 °C in the rock glacier furrow, while the mean annual air temperature was 2.5 °C. Snow cover was inferred from near-surface ground temperature (GST) data, estimating between 130 and 275 days per year and 0.5 to 7.1 m snow thickness. Temperature and BTS data show that the lowest part of the talus slope and the rock glacier furrow are the coldest places in this cirque, coinciding with a more persistent and thickest snow cover. The highest temperatures coincide with less snow cover, fine-grained soils, and higher solar radiation. Snow cover has a primary role in controlling GST, as the delayed appearance in autumn or delayed disappearance in spring have a cooling effect, but no correlation with mean annual near-surface ground temperatures exists. Heavy rain-over-snow events have an important influence on the GST. In the talus slope, air circulation during the snow-covered period produces a cooling effect in the lower part, especially during the summer. Significant inter-annual GST differences were observed that exhibited BTS limitations. A slight positive temperature trend was detected but without statistically significance and less prominent than nearby reference official meteorological stations, so topoclimatic conditions reduced the more global positive temperature trend. Probable existence of permafrost in the rock glacier furrow and the lowest part of the talus slope is claimed; however, future work is necessary to confirm this aspect.S

Snowfall events in the Cantabrian Mountains of northwestern Spain: WRF multiphysics ensemble assessment based on ground and multi-satellite observations

[EN] Snowfall in elevated areas of the mid-latitudes has a strong impact on infrastructure, freshwater availability, and the climate system. The Cantabrian Mountains of the northwestern Iberian Peninsula are very vulnerable to climate change because of their moderate altitudes, which limits their snowfall. Monitoring snow events is essential for the evaluation of weather and climate prediction models. However, measurement networks are scarce in mountainous areas and have great uncertainties because of blizzards. In this study, a multiphysics ensemble of the Weather Research and Forecasting (WRF) model was designed using three microphysics and two planetary boundary layer (PBL) schemes to simulate nine snowfall events in the Cantabrian Mountains during autumn and winter 2021–2022. The WRF was validated using several snow characteristics, such as liquid water equivalent, snow cover, and snow depth. Liquid water equivalent was evaluated using snow-gauge networks and satellite products in an assessment of snow cover. In addition, a monitoring network of webcams and snow poles was implemented, improving the low density of snow observations in the mountains. The results showed good model performance for detection of snow cover and slight overestimation of liquid water equivalent and snow thickness, which may have been caused by under-catchment that is generally an effect of wind on the measurement systems and by snow compaction, respectively. Morrison microphysics and Mellor-Yamada-Nakanishi-Niino (MYNN PBL) yielded better results for liquid water equivalent at higher altitudes and output greater snow cover. The results help determine the best configurations for snow modelling in the study area to develop future studies of the spatiotemporal patterns of snow distribution.S

Estimación de una serie temporal de cubiertas de nieve a partir de registros térmicos de suelo y teledetección en un entorno de alta montaña de la Cordillera Cantábrica (N de la Península Ibérica)

Ponencia presentada en: XII Congreso de la Asociación Española de Climatología celebrado en Santiago de Compostela entre el 19 y el 21 de octubre de 2022.[ES]El análisis de la cubierta de nieve adquiere especial importancia en el estudio del clima de entornos de alta montaña, donde la topografía local influye notablemente sobre los registros térmicos, siendo uno de los principales condicionantes del régimen térmico del suelo, que resulta fundamental en el desarrollo de diversos procesos geomorfológicos y periglaciares. El aislamiento que la nieve produce en determinadas condiciones entre las temperaturas superficiales de suelo y las de aire permite estimar durante qué periodos los emplazamientos se encuentran bajo una cubierta importante de nieve. El objetivo del trabajo ha sido estimar la cubierta de nieve a partir de una serie de 14 años (2006-2020) de temperaturas superficiales de suelo y aire mediante el cálculo de umbrales. Se analizaron registros de 10 localizaciones obtenidas mediante termorregistradores en el circo glaciar de Hoyo Empedrado, situado a más de 2200 m.s.n.m. en la Cordillera Cantábrica. La Teledetección sirve de fuente de validación del método anterior mediante el cálculo de índices espectrales, útiles para el estudio de la cubierta de nieve en áreas de montaña de difícil acceso, aunque limitada por la presencia de nubes. Se han observado diferencias en los registros de cada emplazamiento, explicados por el papel que la topografía juega sobre la distribución de la nieve. Así, en el surco del glaciar rocoso presente en el circo se ha registrado una media (por año hidrológico) de 266 días de cubierta de nieve, mientras que en la vertiente de solana la media es de 126 días.[EN]Snow cover analysis is relevant in the study of high mountain environments climate, where the local topography has a significant influence on the thermal records, being one of the main determinants of the ground thermal regime, which is fundamental in the development of various geomorphological and periglacial processes. The aim is to estimate snow cover from a 14-year series (2006-2020) of ground surface and air temperatures at 10 locations obtained by dataloggers in the glacial cirque of Hoyo Empedrado, located at more than 2200 m.a.s.l. in the Cantabrian Mountains. The isolation that snow produces under certain conditions between ground and air temperatures allows to estimate snow-covered conditions. Remote sensing is used as validation by calculating spectral indexes from Sentinel-2 satellite images. It is a useful tool for the study of snow in mountainous areas that are difficult to access, although it is limited during long periods with cloud cover. Differences have been observed in the records for each site, explained by the role that topography plays in the snow distribution. For example, in the furrow of the rock glacier, an average (per water year) of 266 days of snow cover has been recorded, while on the sunny slope the average is 126 days.Este trabajo forma parte del Proyecto LE080G19 (Significado paleo-ambiental y relación con el cambio global de los glaciares rocosos de la Cordillera Cantábrica: datación relativa y análisis de la estructura interna mediante tomografía eléctrica), financiado por la Junta de Castilla y León, así como de los proyectos previos CGL2006-07404 (Ministerio de Educación y Ciencia) y LE020A07 (Junta de Castilla y León)

Application of the Schmidt-hammer for relative-age dating of glacial and periglacial landforms in the Cantabrian Mountains (NW Spain)

[EN] A Schmidt hammer was applied for relative-age dating to 48 sites in 5 different massifs of the Cantabrian Mountains (NW Spain). The sample included glacial (moraines, erratics, and polished bedrock) and periglacial (rock glaciers, blockfields, and talus slopes) sites from the last glaciation to the present in different geomorphological contexts. The rebound (R) values agree with the morphostratigraphic reconstructions, showing progressively lower values for older deposits. Six stages from the Last Glacial Maximum to the present are inferred. The results differ according to the lithology: i) the quartzites showed higher R-values and very low weathering rates; ii) the granodiorites showed larger differences in R-values reflecting clearly age differences; iii) sandstones appear to be unsuitable for Schmidt hammer measurements in some areas; however, quartzite sandstones provide better results. The rock glaciers formed in different periods after deglaciation (i.e. just after the Last Glacial Maximum, Bölling/Allerød, Holocene), indicate a paraglacial dependence rather than climate-driven landforms. The sampled blockfields stabilized after the (almost) total deglaciation of the cirques, but their origin and significance in this mountainous area remain poorly understood.SIPublicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCL

The origin and collapse of rock glaciers during the Bølling-Allerød interstadial: A new study case from the Cantabrian Mountains (Spain)

.During the Late Pleistocene, the main mountain ranges of the Iberian Peninsula were covered by small icefields and cirque and alpine glaciers. The deglaciation triggered paraglacial processes that generated landforms, mostly within the ice-free glacial cirques. In this research we analyse the deglaciation process in the Muxivén Cirque (42°15′N – 6°16′W), in the upper Sil River Basin, which includes some of the largest relict rock glaciers of the Cantabrian Mountains. We addressed this objective by means of accurate geomorphological reconstructions, sedimentological analysis, Schmidt-hammer surface weathering measurements and a dataset of 10 10Be Cosmic-Ray Exposure ages. Results reveal that after ~16 ka, glaciers retreated to the bottom of the cirques at the headwaters of the valley, leaving the walls free of ice and triggering rock avalanches onto the remnants of these glaciers. This paraglacial process supplied debris to a small glacier within Muxivén Cirque, which transformed in two rock glaciers. These debris isolated the ice inside the rock glaciers only for a very short period of time and ended up melting completely before the Younger Dryas. The lower sector of the largest one stabilized at 14.5 ± 1.5 ka, while the upper sector remained active until 13.5 ± 0.8 ka. Previous to the stabilization of the lower sector of the northern rock glacier, at its margin a high-energy debris avalanche occurred at ~14.0 ± 0.9 ka. These data agree with previous research, corroborating the paraglacial origin of most Iberian rock glaciers during the Bølling-Allerød interstadial.S

The origin and collapse of rock glaciers during the Bølling-Allerød interstadial: A new study case from the Cantabrian Mountains (Spain)

© 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).During the Late Pleistocene, the main mountain ranges of the Iberian Peninsula were covered by small icefields and cirque and alpine glaciers. The deglaciation triggered paraglacial processes that generated landforms, mostly within the ice-free glacial cirques. In this research we analyse the deglaciation process in the Muxivén Cirque (42°15′N – 6°16′W), in the upper Sil River Basin, which includes some of the largest relict rock glaciers of the Cantabrian Mountains. We addressed this objective by means of accurate geomorphological reconstructions, sedimentological analysis, Schmidt-hammer surface weathering measurements and a dataset of 10 10Be Cosmic-Ray Exposure ages. Results reveal that after ~16 ka, glaciers retreated to the bottom of the cirques at the headwaters of the valley, leaving the walls free of ice and triggering rock avalanches onto the remnants of these glaciers. This paraglacial process supplied debris to a small glacier within Muxivén Cirque, which transformed in two rock glaciers. These debris isolated the ice inside the rock glaciers only for a very short period of time and ended up melting completely before the Younger Dryas. The lower sector of the largest one stabilized at 14.5 ± 1.5 ka, while the upper sector remained active until 13.5 ± 0.8 ka. Previous to the stabilization of the lower sector of the northern rock glacier, at its margin a high-energy debris avalanche occurred at ~14.0 ± 0.9 ka. These data agree with previous research, corroborating the paraglacial origin of most Iberian rock glaciers during the Bølling-Allerød interstadial.This research was supported by the project LE080G19 (Paleo-environmental significance and relationship with the global change of the Cantabrian Mountains rock glaciers: relative age dating and analysis of the internal structure using electrical tomography), founded by the Junta de Castilla y León and PR108/20-20 (Santander Bank-UCM Projects). José M. Fernández-Fernández is supported by a postdoctoral grant within the NUNANTAR project, funded by the Fundação para a Ciência e Tecnologia of Portugal (PTDC/CTA-GFI/32002/2017). Marc Oliva is supported by the Ramón y Cajal Program (RYC-2015-17597) and by the Research Group ANTALP (Antarctic, Arctic, Alpine Environments; 2017-SGR-1102) funded by the Government of Catalonia. Adrián Melón-Nava was supported by the FPU program from the Spanish Ministerio de Universidades (FPU20/01220).Peer reviewe

Hoyo Empedrado temperature data serie (2006-2020)

Air and ground surface temperatures have been measured using dataloggers during 14 years (2006-2020) in 10 locations at 2262 and 2471 m.a.s.l. in a glacial cirque of the Cantabrian Mountains (NW Spain). They were placed in a rock glacier (furrow and ridge), a talus slope (5 locations), a sunny slope and a summit. These sites have relevant differences in terms of substrate, solar radiation, orientation and geomorphological context. In this file we present a temperature display showing all records recorded during this 14 years. This file is supplementary material for the manuscript 'Spatial and temporal variability of the ground thermal regime in a mid-latitude glacial cirque (Hoyo Empedrado, Cantabrian Mountains, 2006 – 2020)