Evolution and characteristics of frequency, duration and magnitude of drought events in the central Pyrenees since 1940

The central sectors of the Pyrenees have experienced a significant increase in the average and extreme daily temperature during the last 80 years, as well as a downward trend in precipitation totals (Perez-Zanón et al., 2016). This article addresses the evolution of the number, magnitude and duration of drought events in the Spanish Central Pyrenees from 8 decades of temperature and precipitation records integrated into the high-quality Central Pyrenees data set (Perez-Zanón et al., 2016 ), using the Standardised Precipitation-Evapotranspiration Index (SPEI) index (Begueria et al., 2014; Vicente-Serrano et al., 2010). Series of monthly mean temperature, monthly maximum temperature, monthly minimum temperature and accumulated monthly precipitation corresponding to 15 quality controlled and homogeneity adjusted meteorological observatories have been used. This index has been calculated for 3, 6, 12 and 24 months, in order to analyse its behaviour ​​for different types of drought.

The analysis of SPEI index series indicates a tendency to increase in the frequency of drought events and in their maximum magnitude in the 4 time scales of the SPEI index analysed, especially since the 1980s. This increase in the number of events is also accompanied by an increase in their duration, especially in the case of SPEI3 and SPEI6, although not in the case of SPEI12 and SPEI24

The spatial patterns calculated from the series of the indices also show a clear east-west pattern differentiated between the index signal for the eastern Pyrenees and the western Pyrenees.

REFERENCES

Beguería, S., Vicente-Serrano, S.M., Fergus Reig, Borja Latorre. Standardized Precipitation Evapotranspiration Index (SPEI) revisited (2014): parameter fitting, evapotranspiration models, kernel weighting, tools, datasets and drought monitoring. International Journal of Climatology, 34: 3001-3023

Pérez-Zanón, N., Sigró, J. and Ashcroft, L. (2016), Temperature and precipitation regional climate series over the central Pyrenees during 1910–2013. Int. J. Climatol. DOI:10.1002/joc.4823

Vicente-Serrano S.M., Santiago Beguería, Juan I. López-Moreno, (2010) A Multi-scalar drought index sensitive to global warming: The Standardized Precipitation Evapotranspiration Index - SPEI. Journal of Climate 23: 1696-1718.