In the last half of the twentieth century, the precipitation regime on the Spanish east coast showed an overall pattern of reduction in precipitation totals. This work presents the results from a novel procedure to disaggregate the precipitation series in the Valencia region on the basis of their meteorological origin. Important differences are found between specific trends and changes in the contributions from 1) Atlantic frontal systems, 2) convective–orographic storms, and 3) easterly advections over the Mediterranean Sea (backdoor cold fronts). The series for the three components are then used to analyze the evolution, variability, and spatial distribution of the region’s rainfall and to determine the correlations with the North Atlantic Oscillation (NAO) index. The results establish significant differences between inland areas, with a trend toward decreasing precipitation and thus increasing aridity, and coastal areas, with increasing precipitation that tends to be progressively more torrential in nature. Likewise, the correlations with the NAO index also change and show opposite signs for the different components.

No abstract

Within the area of climate change, summer temperatures are of special interest because of the economic, social and environmental consequences that can derive from their hypothetical increase. A number of recent studies have shown a worldwide trend towards increasing summer temperatures. In this work, we analyse summer temperatures (July and August) in the Valencia region of Spain from 1958 to the present, with the aim of characterising their evolution and detecting any trend towards a higher frequency of warmer days. First results indicate that in our study area there is indeed a higher frequency of days with tropical characteristics and persistent heat; in contrast, we found no tendency to exceed the records of absolute maximum temperatures.

This study is based on the statistical downscaling and spatial interpolation of highresolution temperatures (90 m) over the 1948-2011 period performed for the Valencia Region (east Iberian Peninsula) after considering local topographical factors in the finescale distribution of temperatures. The objective was to detect the areas that were potentially more vulnerable to air temperatures change. This allowed the detection of local climate change patterns, which were analysed and found to be consistent in spatial and temporal terms. These patterns indicate a more marked warming tendency in higher parts of reliefs and their slopes. However, this tendency is less pronounced in bottoms of valleys and on coastal plains, particularly for minimum temperatures, while the tendency for increasing maximum temperatures becomes more generalised. These patterns seem to connect well with regional changes in pressure fields, wind frequency, precipitation patterns and sea surface temperature.

Recent advances in statistical downscaling have allowed the reconstruction of temperatures for the complete 1948-2011 period in a spatial resolution of 90 m and without gaps for the Valencian Community (Spain) and bordering areas. It presently enables analyses in this region, which allows the determination of recent temperature changes at subregional and local scales. The present work focuses on obtaining the thermicity index according to Rivas-Martínez, a well-known indicator of different thermotypes associated with bioclimatic horizons. The change in this index, which has happened in the region between 1948 and 2011, was calculated by generating fine-scale maps of the potential extension of different thermotypes. The results show a greater regression for the thermotypes in a finicolous position, e.g. Orotemperate, Supratemperate and Supramediterranean horizons, which herein indicate greater potential vulnerability in climate change. In the absence of, and given the need for, such fine-scale information, this work should be useful for specialized researchers to spatially limit the potentially most vulnerable biotopes to climate change.

A daily rainfall database covering the Júcar and Segura river basin authorities (east Iberian Peninsula, Spain) with high spatial density without gaps (890 series) has been created for the complete period 1955-2016. This has allowed a trend analysis of precipitation and dry/wet spells with a better spatial detail and coverage of key headwaters sectors than previous studies in this area. Results show significant negative trends for precipitation prevailing in Júcar area (an annual average loss of 51 mm), especially towards its north interior headwaters. For this last one the annual loss exceeds 200 mm (20% of precipitation). By contrast, certain pre-littoral sectors and most of the Segura area are remaining out of these negative trends (some local positive trends). However, the dry spells length and the number of dry days have increased in a generalized way (Júcar and Segura basins) with rainfall concentration in time and space. The decrease of moderate rainfall with greater precipitation effectiveness and weight in the key interior headwaters is the most significant. On the contrary, there has been an increase in extreme torrential rainfall (with poor effectiveness and high risk) at points on the coast and pre-littoral towards south of the region. These results are linked to a change in the frequency of three basic synoptic types identified in the region as rainfall origin.

<p>Para el área de la Comunidad Valenciana (España) se dispone de más de 300 series<br />de temperatura diaria de las que sólo 3 cubren por completo el periodo 1948-2011, y una<br />mayoría menos de la mitad de dicho periodo. El presente trabajo busca reconstruir todas las<br />señales térmicas locales que faltan en el periodo completo 1948-2011 a partir del reanálisis<br />NCEP/NCAR en dicho periodo. Para ello se realiza un downscaling estadístico con los datos<br />observados por medio de una ANN. Ello ha permitido detectar patrones locales de cambio<br />climático que han sido consistentes a lo largo del espacio y tiempo. Estos patrones señalan<br />una tendencia mayor al calentamiento en las partes altas de los relieves y áreas de montaña,y menor en el fondo de los valles. El valor del estudio reside en la detección de las áreas<br />potencialmente más vulnerables al cambio térmico, más que en una determinación exacta de<br />una magnitud global de cambio térmico.</p>

The Regional Atmospheric Modeling System (RAMS) and the Weather Research and Forecasting (WRF) mesoscale models are being used for weather and air quality studies as well as forecasting tools in Numerical Weather Prediction (NWP) systems. In the current study, we perform a comparative assessment of these models under distinct typical atmospheric conditions, classified according to the dominant wind flow and cloudiness, over Eastern Iberian Peninsula. This study is focused on the model representation of key physical processes in terms of meteorology and surface variables during a 7-days period in summer 2011. The hourly outputs produced by these two models are compared not only with observed standard surface variables, measured at different permanent weather stations located over the region of study, but also with different surface remote sensing products and uncoupled Land Surface Models (LSM) datasets. Confronting RAMS and WRF, the current study highlights relevant differences over areas near the coast when mesoscale circulations or Eastern synoptic advections are developed over the region of study. A higher moisture content is observed under these atmospheric conditions, due to the moisture transport by the sea breeze inland. In this regard, it has been found that the Eastern wind field simulated by WRF reaches inland areas and comprises a larger sea breeze extension than RAMS. This sea breeze development impacts meteorology and surface variables in locations not too close to the coast, but still affected by land-sea winds. Additionally, WRF remains more windy and moister than RAMS at night-time, while alike results are found under Western synoptic advections. The results obtained in the current paper show differences under distinct dominant atmospheric conditions, which outline further research in this field in order to achieve more general conclusions.