Chueca, J. and Julián, A., 2004: Relationship between solar radiation and the development and morphology of small cirque glaciers (Maladeta Mountain massif, Central Pyrenees, Spain). Geogr. Ann., 86 A (1): 81-89.ABSTRACT. Spatial and temporal variations in radiative fluxes influence glacier mass-balance in mountain areas. The primary goal of this study was to assess differences in solar radiation on three glacial cirques located in the Maladeta Mountain massif (Central Spanish Pyrenees), and analyse their implications on glacier development and morphology. A quantitative approach is adopted to obtain the values of solar radiation (direct, diffuse and global radiation), combining several field data parameters (measured at 55 control-points) with the solar radiation modelling package Ecosim. The data obtained confirm that the morphologies of the glacial bodies developed in the three cirques have a good correlation with the spatial variation on solar radiation inputs, favouring also the conservation (Aneto and Coronas cirques) or total vanishing (Llosás cirque) of the glacial remnants analysed here. The study shows how strongly in this Alpine-Mediterranean context solar radiation -firstly as a function of latitude and time of year, and locally as a function of topographic slope, aspect and shadowing -controls the mass-balance and the spatial distribution of melting in small glaciers, having an effect on the development of their morphologies.

One hundred and seventy rock glaciers have been identified by use of aerial photographs in the southern Central Pyrenees. Through the use of statistical techniques (quadrat analysis, Poisson distribution analysis and variance‐mean ratio test), differences in lithology and fracturing density are shown to be important controls over their distribution.

Analysis of aerial photographs, GPS mapping and comparison of digital elevation models have been used to quantify the losses in extent and volume observed (1981–2005) in the glaciers of the Maladeta massif (Spanish Pyrenees). The data are examined in relation to different climatic (temperature, precipitation) and topographic factors that control glacial retreat both at the general and local scales. The evolution observed in the massif is characterized by the remarkable surface and volumetric shrinkage registered in all the glaciers: (1) glacial ice decreased in extent 35.7%, reducing from 240.9 ha to 155.0 ha; (2) losses in total ice volume reached 0.0137 km3 (75.6 m w.e.); (3) mean altitude of the studied glaciers increased 43.5 m. These changes seem to have been forced by climatic change (reduction in the snowfall contributions and increase in the maximum temperatures) during the past few decades in this Pyrenean region. In addition, local variables such as the orientation of each glacier, their altitude and their initial size seem to have induced significant spatial differences in the magnitude of the losses.

Permafrost distribution was predicted from measurements of basal temperatures of the winter snow cover using a GIS‐based empirical–statistical modelling approach in a mid‐elevation mountainous area, the northern slope of the Sierra de Telera (central Pyrenees, Spain). A total of 223 basal temperature of snow (BTS) measurements were made over 3 years and a multiple linear regression analysis was performed to model the relationship between BTS measurements and three predictor variables: May solar radiation, elevation and snow‐cover persistence. The snow‐cover persistence factor proved non‐significant and was excluded from the final regression analysis. The model used was statistically significant, and predicted permafrost distribution moderately well (K = 0.52) and with an overall accuracy of 0.79. The results show the importance of solar radiation as an explanatory variable for permafrost conditions in a mid‐elevation mountain area with steep topography. Copyright © 2007 John Wiley & Sons, Ltd.

Glaciar Coronas is one of the small cirque glaciers located in the Maladeta Range, central Spanish Pyrenees. The ice extends from 3220 to 3065 m a.s.l. Using early and modern photographs and aerial photographs, we study the evolution of the glacier during the 20th century, with particular focus on evaluating the variations in area, ice thickness and the withdrawal of the ice front. This information is compared with some basic climatic data (quarterly and annual evolution of temperatures and precipitation) recorded in the nearby Seira observatory. The results show that ice wastage, clearly associated with the main regional climatic evolution, has been dominant during the 20th century at Glaciar Coronas, but the rate has varied and has not been continuous. Three periods have been detected: (1) 1920s–early 1960s: ice depletion period; (2) early 1960s–mid-1980s: stabilization of the deglaciation process; (3) mid-1980s–1998: marked ice depletion period. The study shows a decrease in area of Glaciar Coronas from 19 ha in 1928 to 2.4 ha in 1998. The decrease in length from 1928 to 1998 has been 325 m.