The relationship between circulation weather types (WTs) and the spatial variability of precipitation across the Iberian Peninsula were studied using a high density, quality controlled, homogenized monthly precipitation database with approximately 3000 stations and interpolated to a 10 km grid. The circulation WTs were computed using an objective version of the Lamb classification centered on the Iberian Peninsula. A total of 26 WTs were selected for the period 1948-2003. Daily WTs were grouped to obtain their monthly frequencies, and used as potential independent variables in a linear least-square non-negative regression model with a forward stepwise selection. Results show the impact of each WT on precipitation in the Iberian Peninsula with a spatial resolution which had never been achieved before and additionally were obtained on a monthly scale highlighting the large seasonal cycle observed in each class, and including significantly different patterns in winter and summer. Nevertheless, results confirm that most of the precipitation in the Iberian Peninsula is produced by just a few WTs, with W, SW and C being the most influential. The association between WTs and precipitation is more robust in winter months and for the western IP areas, while it is lower during summer months and for the eastern IP areas. Spatial analysis revealed that precipitation on the Mediterranean coastland is mostly related with easterly flows (NE, E, SE and their hybrid counterparts), while on the Cantabrian coastland. N and NW flows are the most influential WTs. In general, cyclone-related types are the least frequent ones and also the most efficient in generating precipitation; while anticyclone-related types have the highest frequencies, but also the lowest contribution to total monthly rainfall in the Iberian Peninsula.

We have developed a new monthly temperature database for mainland Spain by using the complete holding of maximum and minimum monthly mean values stored at the Spanish National Meteorological Agency (AEMet). After an exhaustive quality control exercise, the data set includes 1358 complete series, and a high-resolution grid (0.1 ∘ × 0.1 ∘ ) was calculated to analyse monthly trends. There has been an uneven increase in the mean values of maximum and minimum temperatures in the Spanish mainland from 1951 to 2010. The maximum monthly mean temperature values have risen mostly in late winter/early spring and the summer, while the minimum monthly mean temperature values have increased in summer, spring and autumn in southern areas. The spatial pattern of the diurnal temperature range shows a clear north-south gradient in summer, with positive trends in the north and negative trends in the south; furthermore, a negative pattern has been detected in the south in spring and autumn. These areas, particularly the Mediterranean coastland, have been subject to dramatic urbanization and land use changes during the past 30 years that may have affected nocturnal temperatures, in particular. Thus, warming processes in the Iberian Peninsula appear to be influenced both by global factors and more local ones, and their effects should be differentiated spatially.

Abstract. Daily Precipitation Concentration Index (CI) was used in this paper to investigate the statistical structure of daily precipitation across Europe based on 530 daily rainfall series for the period 1971-2010. Annual CI shows a NorthWest to South-East gradient (excluding Turkey and Greece). The same gradient is also observed in winter, spring and autumn, while in summer the gradient is North-South. Highest annual and seasonal daily concentrations of rainfall were detected in the western Mediterranean basin, mainly along Spanish and French coastlands. Latitude and distance from the sea seems to play a major role on spatial CI distribution; at subregional scale also relief plays an important role. The Mann-Kendall test did not identify uniform significant pattern in temporal trend across Europe for 1971-2010 period. The only broad areas with increasing annual and seasonal CI values are located in northern and south-western France and northern coastlands of the Iberian Peninsula. This findings suggest that daily precipitation distribution has not significantly changed during the 1971-2010 over Europe.

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.KEY WORDS: Hydrological drought · Meteorological drought · Drought time scales · Standardized precipitation index · Standardized streamflow index · Water management Resale or republication not permitted without written consent of the publisher Editorial responsibility: Gouyu Ren,

The relationships between atmospheric circulation patterns and daily Iberian rainfall are here explored at high spatial resolution (0.2 • ) using the Jenkinson and Collison automated classification scheme with 26 Weather Types (WTs). The WTs were computed by means of the daily EMULATE Mean Sea Level Pressure dataset (EMSLP) while the high resolution precipitation database corresponds to the recent Iberia02 daily gridded precipitation dataset over the 1950-2003 period. Six monthly indexes relating the WTs and precipitation were analyzed: their Frequency, the Mean Precipitation, the Percentage Contribution, the Area of Influence, the Precipitation Intensity, and Efficiency. Except for the Frequency of the WTs, all other indexes were evaluated studying their spatial distribution over the Iberian Peninsula, focusing on a WT and a month at time. A small number of WTs (7) was found to capture a high percentage (∼70%) of monthly Iberian precipitation. The Westerly WT is the most influent one, followed by the Cyclonic, the Northwesterly and the Southwesterly WTs. Westerly flows, however, do not affect the Mediterranean fringe or the Cantabrian coast, which are dominated by the Easterly and Northerly WTs, respectively. Rainfall along the Mediterranean coastline and the Ebro basin depends on a variety of WTs, but their effects are confined to narrow areas and short temporal intervals, suggesting that local factors such as convective processes, orography and the proximity to a warm water body could play a major role in precipitation processes. We show that the use of daily gridded precipitation dataset holds the advantage of measuring the daily rainfall amount due to each WT directly instead to relying on the predicted values of the regression model as done in previous works.