Precipitation In Spain Research Articles

Spatiotemporal variability of the relationship between seasonal temperatures and precipitation in Spain, 1951–2019

Spatiotemporal variability of the relationship between seasonal temperatures and precipitation in Spain, 1951–2019

Climate change effects on sub-daily precipitation in Spain

ABSTRACT Sub-daily extreme precipitation events are responsible for flash floods which generate impacts that cannot be analysed using daily precipitation information. In this study, we assess the effects of climate change in sub-daily rainfall statistics for Spain. We downscale daily records to the hourly scale using machine learning techniques, and then update the downscaling predictors to generate the sub-daily rainfall projections. We use the atmospheric climate change projections of the Coordinated Regional Climate Downscaling Experiment (CORDEX) initiative to update the downscaling predictors. We do not observe important differences between climate change scenarios, except in the average amounts of precipitation. Climate change will intensify the most extreme sub-daily events overall, as well as increase the number of dry spells, although some dry climates concentrate most of the effects. The intensification will increase the 100-year return period event, especially in those regions where large variances are observed, making flash floods more intense in the future.

The separate roles played by the two geographical poles of the NAO in influencing winter precipitation over Spain

In this article, the spatiotemporal relationship between winter (DJF) precipitation over Spain and sea level pressure fields is studied using the Center of Action (COA) approach. The COAs which make up the North Atlantic Oscillation (NAO), i.e., the Azores High (AH) and the Icelandic Low (IL), are considered separately, and we find that interannual variations in the strength and position of the AH explain a very high fraction of the variance of Spain winter precipitation. The correlation of AH properties with winter precipitation is strongest in the northwest of the country. A regression model was developed that explains 83 percent of the variance of the Spain precipitation over 1981–2011. We found that the positive extreme values of AH indices are related to droughts, and negative extremes to heavy rain. The westward and southward shifts of the AH encourage the presence of low pressure system over the Iberian Peninsula and high precipitation in Spain occurs due to the moisture transport off the North Atlantic impinging upon Peninsula Spain and France.

Assessment of climate change impact on maximum precipitation in Spain

AbstractThe potential effect of climate change on maximum precipitation is studied by considering several temporal intervals for its incorporation into flood risk management in Spain. The methodology used allows for a complete assessment of the effect of climate change on maximum precipitation by accounting for uncertainty, and may be applied to other case studies. Behaviour regarding observations, trends and changes in climate model maximum precipitation series are evaluated. In turn, multi‐model mean (and percentile) relative changes accounting for statistical significance, torrential rate changes, and relative changes in daily annual maximum precipitation accumulated along river network are estimated. Results show a large variability in climate model outcomes. In general, a suitable behaviour is found for the climate model ensemble regarding observations: it properly represents seasonality of daily annual maximum precipitation for all regions, and observation‐based statistics are found to be within range of simulation‐based statistics for most regions. As an exception, daily annual maximum precipitation is underestimated in Mediterranean regions, which may be attributed to known limitations of current climate models in adequately reproducing convective precipitation typical of those areas. Results also show an intensifying increase in trends and changes as precipitation duration decreases, a torrentiality rise, and relative changes related to accumulated maximum precipitation of up to 35%. These findings support the notion that the effect of climate change may be stronger for extreme precipitation associated with short precipitation durations. This may be attributed to a stronger scaling between change in extreme precipitation and mean surface temperature increase for shorter durations. The findings also highlight the importance of analysing statistical significance of relative changes in quantile for allowing its attribution to climate change. Statistical model choice is found to be essential for identifying significant changes.

Recent precipitation trends in Peninsular Spain and implications for water infrastructure design

Study regionPeninsular Spain. Study focusThere is strong evidence that climate change has produced a decrease in precipitation combined with an increased frequency, intensity and magnitude of high-intensity storm events in Peninsular Spain. Such events have been particularly recurrent on the Spanish Mediterranean coast in recent years. This study’s first objective is to update the trends in the magnitude and seasonality of precipitation in Spain from 1951 to 2019 at different time scales. Secondly, we analyse how extreme precipitation events recorded in recent years can modify water infrastructure design flows. A QGIS plugin was programmed using Python to calculate the design flows in accordance with the methodologies legally established in Spain. New hydrological insights for the regionThe results confirm the decreasing trend in annual precipitation in most of the Spanish territory. This decrease was particularly significant during March and June. Moreover, the average increases of around 30–40 % in design flows, which reached double the values obtained in the reference period of 1951–1990 in some basins, confirm the relevance of incorporating high-intensity storm events recorded in recent years into flow calculations in Peninsular Spain. Design flows obtained without using the most recent rainfall data can be underestimated, with profound risk implications. Therefore, there is a sufficient technical basis to draw attention to this problem and recommend its formal consideration by competent authorities.

Multifractal fluctuations of the precipitation in Spain (1960–2019)

In this work, an analysis of multifractal parameters of daily precipitation series over the Iberian Peninsula was performed in two 30-year periods to explore whether these properties follow any pattern. Fluctuations of precipitation series show three different scaling regions. Only two distinct regimes for small and large timescales can be confirmed, while intermediate scales are part of a transition region. It is also observed a certain degree of multifractality, which is higher for small timescales. At these scales, there is a high persistence which follows the spatial gradient of the annual precipitation. Moreover, multifractal parameters of the precipitation are modified according to complex spatial and temporal patterns. Only persistence uniformly decreases in the last period. Other relevant findings are the changes in the asymmetry of multifractal spectra in the eastern belt at larger timescales, which might be related to the change in the behavior of the Mediterranean cyclones.

Recent trends reveal decreasing intensity of daily precipitation in Spain

A comprehensive analysis of the spatial and temporal variability of daily precipitation in Spain in the period 1950–2012 was carried out based on the high‐resolution gridded data set SPREAD at a 5 × 5 km spatial resolution. Temporal trends of 12 daily precipitation indices were computed by application of the Sen's slope and the Mann–Kendall tests. The spatial distribution of the trends showed (a) a global slight increase in the duration of the precipitation events, especially along the Mediterranean fringe; (b) an increase of the frequency of low precipitation events and a decrease of the frequency of high and very high events (inverse in the Mediterranean coast); and (c) a slight decrease of the intensity when considering single events (1‐ or 5‐day duration), but a significant negative trend in mean and median precipitation when considering all the precipitation days (p > 0), especially in the Mediterranean coast.

Extreme point rainfall temporal scaling: a long term (1805–2014) regional and seasonal analysis in Spain

ABSTRACTThis paper presents a regional and seasonal study of extreme point rainfall scaling from 10 min to 2 years. To do this, the highest point‐based rainfall list based on these temporal periods was calculated from the Spanish Meteorological Service (AEMET) precipitation databases with more than 11 000 rain‐gauge stations, with the longest series ranging from 1805 to 2014 (209 years). This list constitutes the register of single station largest amounts of precipitation in Spain ever recorded for selected periods, including for example the values for 2 h (193 mm), 24 h (817 mm) or 1 year (5503 mm). Rainfall extremes for 10 min periods are evenly distributed in coastal and inland areas. Daily precipitation extremes are mostly concentrated over the Mediterranean coast while from durations from one month to two years, extremes are located in southern and northwest Spain. Extreme data obtained were compared with existing worldwide rainfall records for equivalent periods. Results indicate that Spanish extreme rainfall scaling relating R depth (in mm) against D duration (in minutes) may be expressed as a potential law R = 21.8 D0.422 (R = 43.6 D0.507 for worldwide data). We propose the upper envelope line (greater or equal to extreme rainfall values) parallel to the potential fit law as a simple method to estimate possible extreme records for different time scales. Using this method, worldwide envelope may be expressed as R = 60.5 D0.507 and the Spanish envelope as R = 39.3 D0.422. Further analysis stratifying results by season and region show that seasonal scaling has more variability than regional scaling. The methodology described can be readily applied to other regions for which detailed rainfall databases exist. Applications of the results include using the scaling found as a reference for classification of heavy precipitation events for temporal scales.

Analysis of downscaled climatic simulations to infer future changes on high precipitation in Spain

ABSTRACTThe potential impact of several downscaled climate simulations (DCS) on high precipitation in Spain during the twenty-first century has been investigated. Two types of precipitation time series, derived from DCS, were used: annual maximum daily precipitation (AMDP) and high precipitation index (R95 T). Statistical tests were applied to detect significant trends (Mann-Kendall test), changes in median (Wilcoxon test), and changes in variance (Fligner-Killeen test), as well as the regional significance of these changes (Binomial test). Furthermore, the SQRT-et-max distribution was adjusted to quantify changes in the AMDP frequency. In general, no clear trends or changes in median, variability or frequency were detected in the AMDP series. R95 T series, though, showed some signs of positive trends and median increments. Thus, a lack of clear patterns of change in high precipitation events may be concluded. Finally, two sources of uncertainty are worth highlighting: the bias of the DCS values when compared with observed data, and the variability among the different DCS results.

Changes in extreme precipitation over Spain using statistical downscaling of CMIP5 projections

ABSTRACTThe Mediterranean coast of Spain often experiences intense rainfall, sometimes reaching remarkable amounts of more than 400 mm in one day. The aim of this work is to study possible changes of extreme precipitation in Spain for this century, simulated from several Coupled Model Intercomparison Project Phase 5 (CMIP5) climate models. Eighteen climate projections (nine models under RCP4.5 and nine RCP8.5 scenarios) were downscaled using a two‐step analogue/regression statistical method. We have selected 144 rain gauges as the rainiest of a network by using a threshold of 250 mm in one day for a return period of 100 years. Observed time‐series have been extended using the ERA40 reanalysis and have subsequently been used to correct the climate projections according to a parametric quantile–quantile method. Five theoretical distributions (Gamma, Weibull, Classical Gumbel, Reversed Gumbel and Log‐logistic) have been used to fit the empirical cumulative functions (entire curves, not only the upper tail) and to estimate the expected precipitation according to several return periods: 10, 20, 50 and 100 years. Results in the projected changes for 2051–2100 compared to 1951–2000 are similar (in terms of sign and value) for the four return periods. The analysed climate projections show that changes in extreme rainfall patterns will be generally less than the natural variability. However, possible changes are detected in some regions: decreases are expected in a few kilometres inland, but with a possible increase in the coastline of southern Valencia and northern Alicante, where the most extreme rainfall was recorded. These results should be interpreted with caution because of the limited number of climate projections; anyway, this work shows that the developed methodology is useful for studying extreme rainfall under several climate scenarios.

Links between teleconnection patterns and precipitation in Spain

This paper describes the relationships between rainfall in Spain (1961–2010) and four teleconnection patterns on three time scales (monthly, seasonal and annual) using data from 144 meteorological stations. Spearman's test was used to carry out partial correlations, and spatial distribution maps of the correlation coefficients were generated with kriging method. We regionalise the study area into homogeneous areas containing weather stations with a similar precipitation response to the patterns.The links between precipitation and the NAO, AO and EA are generally positive in the east and negative in the west of Spain, whereas WeMO correlates positively in the north and negatively in the rest.As a general result, the winter months and winter season show the highest percentage of weather stations with statistically significant correlations. Spearman coefficients of up to 0.62 were found for the NAO, AO and EA. WeMO strongly correlates (values up to 0.55) from October to April.Five areas have been defined: centre/southwest, northwest, north, northeast, and southeast. The mode which best explains rainfall in the two western areas is the NAO; in the north, the WeMO exerts a notable influence; EA correlates better with precipitation in the two eastern zones, especially in spring, autumn and part of winter. They are better controllers of rainfall in these areas than in the whole of the study area.

On the covariability of seasonal temperature and precipitation in Spain, 1956–2005

ABSTRACTIn this work, the covariability between the standardized anomalies of seasonal mean temperature and total rainfall in four Spanish sites during the periods 1956–1980 and 1981–2005 is analysed. Original data are standardized using the reference period 1971–2000. Using the hypothesis of bivariate normal distribution, the climate states corresponding to each period may be characterized by the confidence ellipses at the 95% confidence level. Movements of the ellipses indicate changes in the vector mean (translations), changes in the sign of the correlation coefficient (rotations) and in the variance–covariance matrix (deformations). Significance of these changes is assessed by Hotelling's, difference between correlation coefficients, and Barlett's tests, respectively. Results indicate a general translation towards higher (lower) mean temperature (precipitation) in the second period. Significant changes in the variance–covariance matrix did not show a clear pattern. Future developments of this methodology are outlined.

Circulation types and winter precipitation in Spain

ABSTRACTThis paper is concentrated on the evaluation of circulation type classifications (CTCs) from the European Action COST733 catalogue version 2.0 in terms of their ability to capture winter precipitation, expressed as percentage, over Spanish Iberia and the Balearic Islands. The explained variation, the pseudo‐F statistics and the Brier skill score are used to quantify the explanatory power of circulation classifications. As secondary aims, the impact of using different number of circulation types, additional types of variables and 4‐day sequences in the generation of classifications is analysed.Although no optimal method has been found, nevertheless, the results suggest that the use of CTCs based on optimization algorithms are, in general, performing better than those which are based on other algorithms (i.e. leader algorithms). Distinct variations in skill exist not only among classifications from different groups of basic methods but as well between classifications from the same method group; being remarkable the behaviour of the optimum random centroid method.Results are very dependent on the metric, for the explained variation, and the Brier skill score, the larger the number of circulation types, the better the performance; contrary to the behaviour of the pseudo‐F statistic. The inclusion of 500 hPa vorticity in the generation of classifications improves results while a general deterioration is observed when considering 4‐day sequences. These results are only valid for the selected season and cannot be transferred to other locations and seasons.

Spatial variability of precipitation in Spain

The spatial variability of annual and seasonal precipitation in the conterminous land of Spain has been evaluated by using correlation decay distance analysis (CDD). The CDD analysis essentially explores how the correlation between neighbouring stations varies according to distance. We analysed CDD independently for the decades 1956–1965, 1966–1975, 1976–1985, 1986–1995, and 1996–2005 using only those stations with no missing values for each decade. To this end, 972, 1,174, 1,242, 773 and 695 complete series were used for each decade, respectively. In particular, for each station and decade, we calculated the threshold distance at which the common variance between target (i) and neighbour series is higher than 50 % (r 2 = 0.5) to evaluate whether current density of the climate data set captures the spatial variability of precipitation within the study area. Results indicate that, at an annual scale, neighbouring stations with 50 % of common variance are restricted on average to about 105 km, but this distance can vary from 28 to 251 km within the study area. The lowest variability is located to the SW and in winter, while the higher spatial variability is found to the north, in the Cantabrian area, and to the east, in the Mediterranean and Pyrenees, during summer. Our results suggest that current density of climate stations (those operating in 2005) is good enough to study precipitation variability at an annual scale for winter, spring and autumn, but not enough for summer.

Precipitation concentration changes in Spain 1946–2005

Abstract. An analysis was made of the Precipitation Concentration Index using the new MOPREDAS database of monthly precipitation in Spain (Monthly Precipitation Data base of Spain). The database was compiled after exhaustive quality control of the complete digitalized Spanish Meterological Agency (AEMet) archives and contains a total set of 2670 complete and homogeneous monthly precipitation series from 1946 to 2005. Thus, MOPREDAS currently holds the densest information available for the 1946–2005 period for Spain and ensures a high resolution of results. The Precipitation Concentration Index (PCI) is a powerful indicator of the temporal distribution of precipitation, traditionally applied at annual scales; as the value increases, the more concentrated the precipitation. Furthermore PCI is a part of the well-known Fournier index, with a long tradition on natural system analyses, as for example soil erosion. In this paper, the mean values of annual, seasonal and wet and dry periods of PCI in the conterminous Spain and for two normal periods (1946–1975 and 1976–2005) were studied. Precipitation in Spain follows a general NW-SE spatial pattern during the wet (months) period due to the Atlantic storm track, while during the dry (months) period, it follows a predominantly N-S spatial pattern. As a result, the annual values of PCI combine the two patterns and show a SW-NE PCI gradient. The analyses of the two sub-periods show significant changes in the precipitation occurred in conterminous Spain from 1946 to 2005, and precipitation concentration increased across most of the IP. At an annual scale, PCI increases mostly due to an increase in precipitation concentration during the wet season. At a seasonal scale significant changes were detected between 1945–1975 and 1976–2005, particularly in autumn (increase of PCI values), while changes in winter, spring and summer were mostly localized and not generalized (both increase and decrease). Changes in PCI seem to be complex and appear to be related to global atmospheric features and synoptic and local factors affecting precipitation trends. We discuss the possible explanation linked to the atmospheric pattern and monthly trends and their implications.

Long-term changes in extreme temperatures and precipitation in Spain

La creacio de les bases de dades de temperatura i precipitacio diaries anomenades, respectivament, Spanish Daily Adjusted Temperature Series (SDATS) i Spanish Daily Adjusted Precipitation Series (SDAPS), en el marc del projecte financat per la Comissio Europea EMULATE (European and North Atlantic daily to MULtidecadal climATE variability), ha permes als autors analitzar el canvi a llarg termini que s'ha produit en el comportament anual dels extrems climatics a l'Espanya peninsular durant el periode 1901-2005. El conjunt de procediments desenvolupats pels autors per tal de crear registres homogenis de la temperatura i de la precipitacio diaries son descrits de manera breu abans d'analitzar els canvis observats en l'ocurrencia d'extrems climatics. S'han utilitzat els indicadors se - guents per a dur a terme aquest estudi: excedencies dels percentils inferiors i superiors de les temperatures maximes (Tmax) i minimes (Tmin) diaries, excedencies de la precipitacio diaria per sobre dels percentils 95e i 99e, l'index simple d'intensitat diaria (SDII) i els indicadors d'1 i 5 dies amb la precipitacio mes alta de l'any. Tant l'analisi dels percentils superiors de les temperatures com la dels inferiors mostren que s'ha produit un escalfament important sobre l'Espanya peninsular al llarg del segle XX, i que aquest ha estat mes important en les temperatures maximes que en les temperatures minimes. No obstant aixo, aquest patro presenta un lleuger canvi en el periode mes recent d'escalfament, en el qual la tendencia d'ambdues variables presenta valors similars. Els canvis en els indicadors pluviometrics no son tan clars com els estimats per la temperatura, pero s'ha detectat una tendencia cap a l'ocurrencia de pluges mes intenses.

Seasonal rainfall variations in Spain (1912–2000) and their links to atmospheric circulation

The main aim of the present study is to identify to what degree variability of precipitation in Spain can be attributed to variations in the dominating atmospheric circulation patterns. Statistical models were developed and tested on seasonal precipitation in different regions in Spain during the period 1912–2000. The monthly sea level pressure field (SLP) over the area between the latitudes 30°N and 55°N and longitudes between 25°W and 20°E was used as predictor. Principal components deduced from this field were used as a basis for stepwise multiple regression analysis. The models were developed using even years as a calibration period, while odd years were used as a validation period. Stepwise regression was applied to investigate the relative importance of the predictors. Models reproduce around 68% of the variability in winter precipitation corresponding to western and central Iberian Peninsula, around 20% for Mediterranean coast and 54% for northern coast of Iberian Peninsula. In spring, models reproduce around 57%, 43%, and 27% of the variance for similar regions. In summer and autumn results are worse, although an important fraction of the rainfall variability is captured. The models were then used on the entire period and it is concluded that precipitation changes observed in western Iberian Peninsula during the studied period can mainly be attributed to variations in the SLP field, although topographic effects and/or other causal mechanisms (sea surface temperature, local convective events) must be considered, in addition to SLP field.

Spatial and temporal patterns of precipitation in Spain for the period 1880–1992

Spatial and temporal patterns of precipitation in Spain for the period 1880–1992

Spatial and temporal patterns of precipitation in Spain for the period 1880–1992

The longest series of precipitation records in Spain are analysed using the principal component analysis (PCA) method. EOF analysis was used to spatially summarise the rainfall data and to enable clarification of the role of the dominant circulation regimes affecting the region. Three significant EOFs have been obtained in general, except for summer, when four EOFs are found. The first EOF is associated with Andalusia and the Spanish interior, the second and third EOFs with the Mediterranean and Cantabric coasts, alternatively, depending on the season. The analysis of the principal components series using a moving average and the Mann‐Kendall test, shows significant long term decreases in precipitation for the Mediterranean and interior regions (at least in some seasons), and an increase in precipitation for the Northern coastal region. More of these changes can be related to variations in the large scale circulation features over Western Europe and North Atlantic. The results are also compared with GCM outputs. © 1998 Royal Meteorological Society.

Principal Component Analysis of precipitation and rainfall regionalization in Spain

A T-mode Principal Component Analysis (PCA) based on a network including 68 pluviometric gauges and their 12 mean monthly amounts of rainfall is attempted in order to describe the main patterns governing precipitation in Spain. The procedure is applied to a 12 × 12 intermonth covariance matrix; the unrotated components and two additional solutions deduced after varimax and oblimin rotations are presented and discussed. In all cases component scores are computed and their spatial distribution is discussed. Two regionalizations of Spanish rainfall are then obtained and compared in terms of group homogeneity. There follows a discussion concerning the main pluviometric characteristics of each region deduced from the best division.