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.

A torrential rain event took place in the Valencia region in October 2007, mainly affecting coastal areas and nearby mountains in the center-south of the region, in northern Alicante province. More than 400 mm in 24 h were recorded at some stations in these areas, with lower accumulations in the rest of the region where rainfall was less intense. In the first part of this work a description of the meteorological situation is given. The synoptic frame of the event is characterised by an advection of easterly maritime winds across the Western Mediterranean, lasting for at least 48 h, driving moist air towards the Iberian Peninsula eastern coast and the presence of an upper level isolated low over Eastern Iberian Peninsula. Then, the results of numerical simulations using the Regional Atmospheric Modelling System model are shown to study the rain event in detail. The Regional Atmospheric Modelling System reproduces satisfactorily the spatial distribution of the rainfall and the rain period, but it underestimates precipitation in the areas with the most intense values. Finally, a sensitivity test was performed in order to evaluate the role of orography in the rain event, showing the importance of orography as a triggering mechanism.

Many previous research studies have shown how local and even regional earthquakes can significantly affect the release of radon in the soil. The aim of this work is to investigate the relationship between radon measurements and the daily seismic activity rate and develop a methodology that allows estimating the seismic activity rate using only radon measurements. To carry out this study, the earthquake catalogue of the Vrancea region (Romania) has been used to estimate the daily seismic activity rate during a given time period, in which radon measurements were also recorded, from January 2016 to September 2020. The Vrancea zone represents the most active seismic zone in Europe and is located on the eastern edge of the strongly bent Carpathian arc. In the case of the radon measurements, seasonal behaviours and linear trends due to non-seismic factors have been identified and subsequently removed. The discrete wavelet transform has been used to analyse the radon signal at two different scales: long and short periods. From the analysis carried out on a long-period scale, an approximate linear relationship has been obtained between the radon series and the daily seismic activity rate, which provides insights into the behaviour of the seismic activity in the study region with only the radon information. In addition, the study reveals certain characteristics that could be used as precursors of earthquakes at different scales: weeks in the case of the estimated daily seismic activity rate, and days in the case of the short-period signal obtained by the wavelet analysis. The results obtained for this region allow us to hope that the analysis of the radon time series can become an effective complement to the conventional seismic analysis used in operational earthquake forecasting.

Solar radiation is a key factor in the Earth’s energy balance and it is used as a crucial input parameter in many disciplines such as ecology, agriculture, solar energy and hydrology. Thus, accurate information of the global downward surface shortwave flux integration into the grid is of significant importance. From the different strategies used for grid integration of the surface solar radiation estimates, satellite-derived and numerical weather prediction forecasts are two interesting alternatives. In the current work, we present a comprehensive evaluation of the global downward solar radiation forecasts provided by the Regional Atmospheric Modeling System (RAMS) and the Downwelling Surface Shortwave Flux (DSSF) product, derived from the Meteosat Second Generation (MSG) Spinning Enhanced Visible and Infrared Imager (SEVIRI). Both solar radiation estimates are compared to thirteen ground-based weather station measurements for the winter 2010–2011 and the summer 2011 seasons. For these periods, the most recent versions of RAMS (4.4 and 6.0) were running in parallel within the real-time weather forecasting system implemented over the Valencia Region. The solar radiation performance and accuracy are evaluated for these datasets segmented into two atmospheric conditions (clear and cloudy skies) and two terrain classes (flat and hilly). DSSF shows a very good agreement over the study area. Statistical daily evaluations show that corresponding errors vary between seasons, with absolute bias ranging from −30 to 40 W·m⁻², absolute root mean square errors (RMSE) from 25 to 60 W·m⁻², relative bias ranging from −11% to 7% and relative RMSE from 7% to 22%, depending on the sky condition and the terrain location as well, thus reproducing the observations more faithfully than RAMS, which produces higher errors in comparison to the measurements. In this regard, statistical daily evaluations show absolute bias values varying from −50 to 160 W·m⁻², absolute RMSE from 60 to 240 W·m⁻², relative bias ranging from −30% to 40% and relative RMSE from 10% to 80%, also depending on the daily initialization and the forecast horizon. This bias variability demonstrates that there is a different trend in the deviation of the model results in relation to the observations, both for the DSSF product and RAMS forecasts, and considering the summer and the winter seasons independently. In this regard, although there is an overestimation of the observed solar radiation within the summer months, this magnitude is underestimated during the winter. Finally, comparing this solar radiation estimates for different atmospheric conditions and different terrain classes, the best results are found under clear skies over flat terrain. This result is achieved using both methodologies.