Both renewable energy supply and electricity demand are strongly influenced by meteorological conditions and their evolution over time in terms of climate variability and climate change. However, ...knowledge of power output and demand forecasting beyond a few days remains poor. Current methodologies assume that long-term resource availability is constant, ignoring the fact that future wind resources could be significantly different from the past wind energy conditions. Such uncertainties create risks that affect investment in wind energy projects at the operational stage where energy yields affect cash flow and the balance of the grid. Here we assess whether sub-seasonal to seasonal climate predictions (S2S) can skilfully predict wind speed in Europe. To illustrate S2S potential applications, two periods with an unusual climate behaviour affecting the energy market will be presented. We find that wind speed forecasted using S2S exhibits predictability some weeks and months in advance in important regions for the energy sector such as the North Sea. If S2S are incorporated into planning activities for energy traders, energy producers, plant operators, plant investors, they could help improve management climate variability related risks.
In this study we assessed the impact of meteorological droughts on streamflow droughts in 187 river basins of the Iberian Peninsula. For each basin we correlated the 1 mo to 48 mo standardized ...precipitation index (SPI) with the standardized streamflow index to assess the response time of streamflow droughts to the SPI, and to determine the best climatic time scale over which to monitor hydrological droughts. In addition, we analyzed the effects of dam construction and reservoir use on changes in the response of hydrological droughts. The analysis revealed 2 main types of hydrological drought response to meteorological drought: (1) a peak response pattern involving enhanced hydrological sensitivity at short SPI time scales, which largely characterized basins in the northern sector of the Iberian Peninsula, and (2) a sustained response pattern involving greater sensitivity to meteorological droughts at much longer time scales, which primarily characterized the central and southern basins of the Iberian Peninsula. Water management has significantly altered the natural hydrological response to meteorological droughts, delaying the impacts of precipitation deficits over long time scales, especially downstream of reservoirs used for irrigation purposes.
The climate of the Iberian Peninsula is highly variable due to geographic and atmospheric factors. To better understand and characterize this variability in this work a stepwise regression procedure ...is used to model the relationship between the atmospheric circulation patterns (expressed by weather types) and the monthly mean value of maximum and minimum temperatures in the Iberian Peninsula (1950–2010). The study uses a temperature database with high spatial resolution that allows the estimation of the type and strength of the relationship between weather types and temperatures, and also the definition of spatial areas with specific behaviors for each month. The results show that estimations are better for Tmin than Tmax, during winter months than summer ones, and in coastal areas than inland. The analyses of directional weather types and temperature show a generalized adiabatic processes across Iberian Peninsula affecting Tmax, not detected in Tmin.
•The relationship between weather types (based on Lamb's classification -1972- and proposed by Trigo and Da Camara -2000-) and average monthly maximum (Tmax) and minimum (Tmin) temperatures (1950-2010).•The study shows different behaviours for Tmax and Tmin for each month, weather type and especially in the spatial domain (thanks to the high spatial density of the information used).•Each weather type implies a positive or negative influence (°C) on the average temperatures, depending on its nature, which is affected by other factors such as the relief.•The final goal of the study is to generate a multivariate stepwise regression model that selects, for each pixel and month, the weather types that best explain temperatures.•The results show that estimations are better for Tmin than Tmax, during winter months than summer ones, and in coastal areas than inland.
This study presents a new climatology of monthly temperature for mainland Spain (1951-2010), performed with the highest quality and spatially dense, up-to-date monthly temperature dataset available ...in the study area (MOTEDAS).
Three different interpolation techniques were evaluated: the Local Weighted Linear Regression (LWLR), the Regression-Kriging (RK) and the Regression-Kriging with stepwise selection (RKS), a modification of RK. The performances of the different models were evaluated by the leave-one-out validation procedure, comparing the results from the models with the original data and calculating different error measurements.
The three techniques performed better for T
max
than for T
min
, and for the cold, rather than warmer months, also at lower altitude than highland areas. The best results were achieved with LWLR applied for the first time on temperatures in the Spanish mainland. This method improved the accuracy of the temperature reconstruction with respect to RK and RKS.
We present a collection of T
max
and T
min
monthly charts, using the same temperature legend to prevent any visual bias in the interpretation of the results. The dataset is available upon request.
The spatial variability of monthly diurnal and nocturnal mean values of temperature in Spain has been analysed to evaluate the optimal threshold distance between neighbouring stations that make a ...meteorological network (in terms of stations’ density) well representative of the conterminous land of Spain. To this end, the correlation decay distance has been calculated using the highest quality monthly available temperature series (1981–2010) from AEMet (National Spanish Meteorological Agency). In the conterminous land of Spain, the distance at which couples of stations have a common variance above the selected threshold (50 %,
r
Pearson ∼0.70) for both maximum and minimum temperature on average does not exceed 400 km, with relevant spatial and temporal differences, and in extended areas of Spain, this value is lower than 200 km. The spatial variability for minimum temperature is higher than for maximum, except in cold months when the reverse is true. Spatially, highest values are located in both diurnal and nocturnal temperatures to the southeastern coastland and lower spatial variability is found to the inland areas, and thus the spatial variability shows a clear coastland-to-inland gradient at annual and monthly scale. Monthly analyses show that the highest spatial variability in maximum and minimum temperatures occur in July and August, when radiation is maximum, and in lowland areas, (<200 m o.s.l.), which coincide with the mostly transformed landscapes, particularly by irrigation and urbanization. These results highlight local factors could play a major role on spatial variability of temperature. Being maximum and minimum temperature interstation correlation values highly variable in Spanish land, an average of threshold distance of about 200 km as a limit value for a well representative network should be recommended for climate analyses,.
Precipitation has been recognized as one of the main factors driving soil erosion and sediment yield (SY), and its spatial and temporal variability is recognized as one of the main reasons for ...spatial and temporal analyses of soil erosion variability. The weather types (WTs) approach classifies the continuum of atmospheric circulation into a small number of categories or types and has been proven a good indicator of the spatial and temporal variability of precipitation. Thus, the main objective of this study is to analyze the relationship between WTs, runoff, soil erosion (measured in plots), and sediment yield (measured in catchments) in different areas of the Iberian Peninsula (IP) with the aim of detecting spatial variations in these relationships. To this end, hydrological and sediment information covering the IP from several Spanish research teams has been combined, and related with daily WTs estimated by using the NMC/NCAR 40-Year Reanalysis Project. The results show that, in general, a few WTs (particularly westerly, southwesterly and cyclonic) provide the largest amounts of precipitation; and southwesterly, northwesterly and westerly WTs play an important role in runoff generation, erosion and sediment yield as they coincide with the wettest WTs. However, this study highlights the spatial variability of erosion and sediment yield in the IP according to WT, differentiating (1) areas under the influence of north and/or north-westerly flows (the north coast of Cantabria and inland central areas), (2) areas under the influence of westerly, southwesterly and cyclonic WTs (western and southwestern IP), (3) areas in which erosion and sediment yield are controlled by easterly flows (Mediterranean coastland), and (4) lastly, a transitional zone in the inland northeast Ebro catchment, where we detected a high variability in the effects of WTs on erosion. Overall results suggest that the use of WTs derived from observed atmospheric pressure patterns could be a useful tool for inclusion in future projections of the spatial variability of erosion and sediment yield, as models capture pressure fields reliably.
•The relationships between WTs, precipitation, runoff and sediment yield are tested.•Spatial variations in these relationships were detected according to WT.•A few WTs, particularly W, SW and C, provide the largest amounts of precipitation.•SW, NW and W WTs play an important role in runoff, erosion and sediment yield.
Substantial evidence suggests that oxidative modifications of low density lipoproteins (LDL) critically contribute to the pathogenesis and progression of human atherosclerosis. Oxidized LDL (oxLDL) ...are present in atherosclerotic plaques and contain oxysterols that exhibit a variety of adverse biological activities. Antioxidants have also been shown to prevent LDL modification. We have therefore assessed the efficacy of virgin olive oil phenolic compounds in preventing oxidative modifications of human LDL oxidized by UV light.
Cholesterol oxides formed during LDL photo-oxidation were determined by UV-HPLC in the presence of different concentrations of phenolic compounds and their pure components (tyrosol and oleuropein), and probucol, a widely used synthetic antioxidant. Electrophoretic mobility was also assayed. The results demonstrate that phenolic compounds are much more potent in preventing cholesterol oxide formation and apoproteic moiety modification than their pure components and probucol.
The beneficial effects of a Mediterranean diet may be ascribable not only to the high unsaturated/saturated fatty acid ratio characteristic of olive oil, but also to the unique antioxidant properties of its phenolic compounds.
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