CR 63:43-60 (2015)  -  DOI: https://doi.org/10.3354/cr01287

ABSTRACT: This work evaluates recent (1970-2007) climatic changes in the southeastern Iberian Peninsula, a semi-arid region with important human pressure. The high-resolution dataset Spain02 (~20 km) was used. This allowed us to discover local/regional signals, most of them not previously reported because of the use of coarse data or interpolation techniques. Annual precipitation has not experienced long-term changes in most of the region (80%) but showed some negative trends in the wettest mountainous NW area and slight recovery in the most arid S/SE region, mainly due to changes during winter. However, an increase in long-term droughts, examined at 4 locations, was found, which seems highly connected to a temperature increase. Both maximum and minimum temperatures (Tmax, Tmin) have increased in most of the region (in 70 and 88% of the area, respectively) at high rates (average 0.5 and 0.52°C decade^-1 for Tmax and Tmin, respectively), with steepest trends in spring and summer and distinct subregional differences. Thus, the diurnal temperature range decreased in the most populated areas in the NE and the S/SW (25% of the region), whereas it mainly increased in natural and mountainous areas (15%). Combined indices showed increasing frequency of warm-dry and warm-wet days and less cold days, especially in the central W and NE. Precipitation intensity increased within warm-wet days in the transition seasons (40% of the region), suggesting enhanced convective events, even where total precipitation did not change. Besides large-scale factors, we discuss precipitation-temperature feedbacks and land cover changes in the analyzed period (i.e. increase in mountainous forested areas, urban and agricultural intensification in coastal flatlands), possibly affecting the observed signals. Given the relatively low density of long-term records from which the Spain02 was built, caution is needed in the interpretation of results, especially for temperature in altitude gradients.

KEY WORDS: SE Spain · Precipitation · Maximum temperatures · Minimum temperatures · Spain02 · SPEI · Joint temperature-precipitation modes · Subregional trends · Land cover changes