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This study investigated the temporal variability and changes in snow cover duration and the average snow depth from December to April in the Pyrenees at 1,500 and 2,100 m a.s.l. for the period 1958–2017. This is the first such analysis for the entire mountain range using SAFRAN‐Crocus simulations run for this specific purpose. The SAFRAN‐Crocus simulations were evaluated for the period 1980–2016 using 28 in situ snow depth data time series, and for the period 2000–2017 using MODIS observations of the snow cover duration. Following confirmation that the simulated snow series satisfactorily reproduced the observed evolution of the snowpack, the Mann–Kendall test showed that snow cover duration and average depth decreased during the full study period, but this was only statistically significant at 2,100 m a.s.l. The temporal evolution in the snow series indicated marked differences among massifs, elevations, and snow variables. In general, the most western massifs of the French Pyrenees underwent a greater decrease in the snowpack, while in some eastern massifs the snowpack did not decrease, and in some cases increased at 1,500 m a.s.l. The results suggest that the trends were consistent over time, as they were little affected by the start and end year of the study period, except if trends are computed only starting after 1980, when no significant trends were apparent. Most of the observed negative trends were not correlated with changes in the atmospheric circulation patterns during the snow season. This suggests that the continuous warming in the Pyrenees since the beginning of the industrial period, and particularly the sharp increase since 1955, is a major driver explaining the snow cover decline in the Pyrenees. [ABSTRACT FROM AUTHOR]

Many studies have investigated the climate variability of specific areas in the Pyrenees. However, due to the complexity of obtaining data from three different countries, a study of the Pyrenees as a whole was still missing. Here, for the first time and under the framework of the CLIM'PY project, scientists from Spain, France and Andorra are working together to create a common temperature and precipitation database. We collected 1,495 precipitation and 1,331 temperature series of both sides of the mountain range to create: 1) a high-resolution gridded dataset (1x1 km) including daily data for the period 1981-2015; and 2) a long-term monthly dataset based on 61 temperature and 119 precipitation homogenized series for the period 1950-2015. Then, we calculated the annual, seasonal and monthly trends. Likewise, we computed a set of 27 extreme precipitation and temperature indices from the World Meteorological Organization, as well as their trends, to assess the spatial distribution and long-term variability of the climate in the Pyrenees.Overall, we discovered an increase of both annual (0.2 ºC/decade) and seasonal temperature, especially in spring and summer (0.3 ºC/decade), and a slight decrease in precipitation (-1.8 %/decade), although in general not significant and including a high spatial variability. This decrease is significant, however, in the southernmost side and can be seen in the spatial distribution of all daily and extreme indices of precipitation. This study represents the first step to assess the impacts of climate change in the whole Pyrenees, helping achieve a better management of a territory that highly depends on climate (tourism, agriculture, etc.) and with a great ecological diversity. [ABSTRACT FROM AUTHOR]