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Catalonia - Climate

Catalonia FlagIts climate consequently varies, depending on the terrain. The coastal area has a Mediterranean climate, with mild winters and hot summers. Further inland, the climate is more continental, with cold winters and very hot summers. Snowy winters and mild temperatures in summer are features of the climate high in the mountains to the north.

It is of paramount interest to downscale climate simulations in areas such as Catalonia, since its complex orography and landsea contrast are largely misrepresented in global models. Climate projections reveal a robust temperature rising trend over Catalonia for the coming decades. This warming trend is shown over all time horizons, seasons, and geographical/ climatic areas in Catalonia. The surface temperature increase could be +0.8 C by 2020, and even reach +1.4 C by mid century, as compared to the reference period 1971-2000. The rising trends may be even more powerful for the Pyrenean region, particularly in the summer. As for rainfall, the climate projections show a decreasing trend, but with an uncertain slope. Indeed, variation of rainfall rate in the current decade is barely significant.

By mid century, on the contrary, decrease in rainfall is clear, with a median in distribution of estimated values around 10 % in spring, summer and autumn. The likely increase in torrential rainfall will also increase flood risks. There are signs that drought may be increasing in frequency and severity. Higher temperatures stimulate evapotranspiration. The snow mantle shrinks and melting occurs ever earlier. This, together with the reforestation of the headwaters of most basins, is causing a decrease in river flow. These trends will continue in the future. Thus, meteorological, hydrological and agricultural drought will be more frequent and severe over the 21st century, affecting water resources, water quality, ecosystems and wildfires.

There had been an increase in mean yearly air temperature of +0.23 C/decade, for Catalonia as a whole and for years 1950-2014, with an increase rate of mean annual maximum temperature of +0.28 C/decade, higher than the raise in minimum temperature, of +0.17 C/decade. Across seasons, the average temperature increase is highest in the summer: +0.33 C/ decade. In contrast, yearly rainfall rate does not show a statistically significant variation for the whole country. Moreover, along with the increase in temperature, there had been a statistically significant raise in number of hot and warm days, hot summer nights and sea surface temperature at the Costa Brava, while a statistically significant decrease had been reported for number of cold days and cold nights as well as for days of snow.

A significant positive trend in major avalanche activity had been observed from the early 70s. As for avalanche types, there had been an increase in wet snow avalanches and their magnitude, although data are insufficient to draw a trend. In this respect, cycles of wet avalanches due to rain in 2013-2014 and 2014-2015 are remarkable. As for the Catalan Pyrenees area, a statistically significant negative correlation had been described for the lasts 40 years between occurrence of major avalanche cycles and the North Atlantic Oscillation (NAO).

The latitudinal situation of the Principality, between the temperate and tropical climatic zones, the position between two seas and two continents and the huge geographical variety of the territory, makes Catalonia a country with a unique mosaic of climates and with a great meteorological complexity. Few areas with the extension of Catalonia meet their climatic diversity, still to know themselves on a fine scale, and face the challenge of such a complicated weather prognosis. The game of several factors determines the uniqueness and climatic variety of the country, factors that can be grouped into two large sets: those linked to the general atmospheric dynamics and those that are geographically proper.

Given its latitude and western location on the Eurasian continent, the climate of Catalonia had its own Mediterranean features, but it participates in other extremes, which are typical of the climatic zones between which it is framed. It is an air mass contact area with different characteristics: cold or polar, from medium and high latitudes, and warm or tropical, typical of subtropical and tropical latitudes. The first is mainly felt during the cold months of the year, while the second, characterized by an anticyclone in the middle and upper layers of the troposphere, is predominant during the summer. For this reason, the summer quarter will be dry and the rest of the year, moderately humid.

On the other hand, the position of Catalonia, in the West European and east of the Iberian Peninsula, confers some atypical features on its Mediterranean general: winter is not a rainy season in Catalonia, due to its position in Leeward of Atlantic weather. The Atlantic Ocean is in the west, but clearly separated from the Catalan territory due to the high Iberian lands. These can act as an aerial barrier, mitigating and modifying the Atlantic influence. On the coast and in the pre-littoral it will be the autumn, the rainiest season, with maximum thermal contrasts between the Mediterranean waters and the first cold streams. Finally, the climate is clarified by the proximity of the African continent, where its origin had some of the types of weather that affect it.

The geographic variety of Catalonia is truly extraordinary, especially if its modest extension is taken into account. The range of altitudes covers more than 3,000 meters, producing climatic floors, especially thermal, that give annual average temperatures from 17 C to 0 C. The orography is very compartmentalized in mountains and depressions. This factor, combined with different orientations in its relief units, produces great climatic and meteorological contrasts between counties and their neighbors. A good demonstration of these contrasts is found in the annual average rainfall map, where rainfall totals range from more than 1,200 mm to certain points in the Pyrenees, and less than 400 mm to the west of the central depression.

The parallel layout on the coast of the Litoral and Prelitoral mountain ranges leaves the inner lands of the maritime influence, more than the modest straight line distance would mean. This shows clear continental features in the central Catalan depression as opposed to the influence of Mediterranean waters on the coast.

In short, with the exception of the Aran Valley, of Atlantic climate, Catalonia in general will be characterized, broadly, by winters with mild temperatures and hot summers and dry. The rainfall is very irregular. The presence of the Mediterranean air mass moderates the temperatures at the same time that torrential rain can originate in autumn, especially in the coastal and pre-coastal zone. As you move towards the interior, the thermal and rainfall characteristics are modified, generally increasing the thermal amplitude and decreasing the precipitation. Thus, in Central Depression winters are cold and thermal inversion mists abound, while summers are very hot and dry. In mountain areas, temperatures are lower and precipitation is more abundant. In the Eastern Pyrenees, the rainiest season is summer, due to the large number of summer storms. On the other hand, the position of Catalonia between Eurasia and Africa and the border between the tropical and polar air masses.

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Page last modified: 27-09-2017 18:44:56 ZULU