Comparison of Near-Surface Attenuation from Surface Array-Based Seismic Noise Data and Borehole Weak-Motion Recordings at the STIN Test Site in Northeastern Italy

The climate of Sierra Nevada conditions many relevant aspects for the living systems that inhabit it as well as the water resources of a region with semi-arid characteristics. Climate change in Sierra Nevada can be especially exacerbated by its mountain condition in a Mediterranean area, which makes it a double climate change hotspot. This chapter focuses on describing the main climate characteristics of Sierra Nevada as well as the recent trends and climate change projections for the near future (2020–2050) and the far future (2070–2100) for the principal climate variables. Precipitation in Sierra Nevada is characterized by marked inter and intraannual variability, a typical condition of the Mediterranean climate, and is mainly concentrated between the months from October to April, with a clear gradient west–east. This variability is mainly driven by the North Atlantic Oscillation (NAO) over the western part, meanwhile the eastern part is more dominated by Mediterranean depressions, and particularly by the Western Mediterranean Oscillation (WeMO). On the other hand, the altitude has a limited impact on rainfall distribution. The influence of altitude is clearer for both maximum and minimum temperature, being, in general, lower for minimum temperature. Both temperatures show increasing trends during the last decades, although with a more generalized spatial pattern for minimum ones. According to this increase, significant positive trends are found for extreme event indices associated with warm days as well as a marked increase of potential evapotranspiration (ET0). There is a prevailing decrease in annual and winter precipitation for the whole area, related with significant negative trends over the western part of Sierra Nevada. However, this fact does not translate into an increase in drought episodes characterized by Standardised Precipitation Index (SPI), being the enhanced drought conditions related to a more atmospheric demand. Climate projections from an ensemble of Euro-CORDEX regional models simulations depict clear warming along with drier conditions over Sierra Nevada, more intense for the far future under the RCP8.5 scenario. The results from the ensemble mean reveal reductions in evapotranspiration for most Sierra Nevada, with only moderate increases at higher altitudes in winter and spring probably related by an increase in potential evapotranspiration and increased temperature. The total soil moisture content is projected to decrease under the RCP8.5 scenario for all Sierra Nevada. Drought events are likely to become slightly longer and more frequent in the near future, over the entire Sierra Nevada, with a marked increase in duration and intensity for the far future.