Spatio‐temporal variability of daily precipitation concentration in Spain based on a high‐resolution gridded data set

Northern Chile is one of the most arid regions in the world, as it includes the Atacama Desert. At high elevations, most precipitation is observed only during a short period of the year, from December until March. This renders water availability a major concern for policymakers. Accumulated rainfall varies considerably from one year to another, and for this reason, climate projections have a very low degree of confidence in this area. Consequently, in this region, it is more interesting to study the irregularity of precipitation itself than accumulated rainfall values, as they express in a clearer way the behaviour of precipitation. According to daily data from 161 meteorological stations, four irregularity indices of precipitation were calculated: concentration index, entropy, persistence index, and fractal dimension. These indices were measured according to observed values, and their spatial distribution was subsequently determined by interpolating following multivariate regression models that consider different geographical variables such as latitude, distance to the Amazon Basin, elevation, orientation, and curvature. The temporal trends of each index and for each meteorological station were also calculated, displaying different results depending on the latitude and elevation. These changes agree with the observed modifications on the inter‐tropical atmospheric circulation and with changes in the precipitation diurnal cycle. These results will help improve climate projections for this region, in the process facilitating the development of more accurate climate models and informing the formulation of water management policies.

Section: Discussioncontrasting

confidence: 99%

Spatial distribution and trends of different precipitation variability indices based on daily data in Northern Chile between 1966 and 2015

Meseguer-Ruiz

Ponce-Philimon

Guijarro

et al. 2019

“…No relation was found between the mean annual rainfall values and CI and n or . Similar results were obtained for Spain (Martin-Vide, 2004;Serrano-Notivoli et al, 2018), Italy (Coscarelli and Caloiero, 2012) and Turkey (Yeşilırmak and Atatanir, 2016). The results have indicated that in each of the years for which the precipitation concentration falls within the strong irregular range, the values of CI and n or (>0.66-0.60, respectively) correspond approximately to 75% of the precipitation being contributed by 25% of the rainiest days.…”

Section: Spatial Distribution Of Daily Precipitation Concentration supporting

confidence: 78%

“…Significant negative correlations were detectable between the number of rainy days and both CI and n or throughout the MR ( r = −0.50, r = −0.35, p < .05), respectively, so the higher rainfall concentrations are observed in the areas with fewer rainy days. No relation was found between the mean annual rainfall values and CI and n or . Similar results were obtained for Spain (Martin‐Vide, ; Serrano‐Notivoli et al ., ), Italy (Coscarelli and Caloiero, ) and Turkey (Yeşilırmak and Atatanir, ). The results have indicated that in each of the years for which the precipitation concentration falls within the strong irregular range, the values of CI and n or (>0.66–0.60, respectively) correspond approximately to 75% of the precipitation being contributed by 25% of the rainiest days.…”

Section: Resultsmentioning

confidence: 99%

“…Studying of temporal distribution of heavy rainfall events is very important to evaluate the amount of runoff and soil erosion and also can modify water availability, groundwater recharge and hydroelectric production (De Lima et al, 2013;Yu et al, 2018). Several studies on spatial and temporal variations of precipitation concentration have been undertaken all over the world to study the statistical structure of daily precipitation according to its concentration during the year and evaluate the heaviest precipitation events (Monjo and Martin-Vide, 2016;Yeşilırmak and Atatanir, 2016;Royé and Martin, 2017;Zheng et al, 2017;Serrano-Notivoli et al, 2018). Concentration index (CI) by Martin-Vide (2004) is based on the fact that the contribution of the days of a given rainfall to the total amounts of annual precipitation is generally adjustable by a negative exponential distribution.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Spatiotemporal variability of daily precipitation concentration and its relationship to teleconnection patterns over the Mediterranean during 1975–2015

Mathbout

López-Bustins

Royé

et al. 2019

This study has addressed the spatiotemporal distribution of the daily rainfall concentration and its relation to the teleconnection patterns across the Mediterranean (MR). Daily concentration index (CI) and the ordered n index ( nor) are used at annual time scale to reveal the statistical structure of precipitation across the MR based on 233 daily rainfall series for the period 1975–2015. Eight teleconnection patterns, North Atlantic Oscillation (NAO), Mediterranean Oscillation (MO), Western Mediterranean Oscillation (WeMO), Upper‐Level Mediterranean Oscillation index (ULMO), East Atlantic (EA) pattern, East Atlantic/West Russia (EATL/WRUS) pattern, Scandinavia (SCAND) pattern and Southern Oscillation (SO) at annual time scale are selected. The spatiotemporal patterns in precipitation concentration indices, annual precipitation and their teleconnections with previous large‐scale circulations are investigated. Results show a strong connection between the CI and the nor (r = 0.70, p < .05) which present the same relative areas of high and low concentration. The annual values range from 0.57 to 0.70 for CI and 0.49 to 0.71 for nor index which show a high daily precipitation concentration across the MR. Trend analysis demonstrated mostly significant increasing trends for both indices. This increase is mainly found in south France, northern coastlands of the Iberian Peninsula (IP), Greece and Tunisia. An inverse relationship between the number of rainy days and concentration indices is evident. Both of WeMO and MO can play an important role in modulating rainfall in the northwest Mediterranean. The positive EATL/WRUS phase is mainly connected with positive precipitation mean anomalies in the eastern Mediterranean and vice versa in the west. The high daily precipitation concentration values over south France, northeast Spain, Croatia and Tunisia are linked to the low values of WeMO and high values of EA. These results could pave the way for new possibilities regarding the projection of precipitation concentration and precipitation irregularity in downscaling techniques.

“…The CI values calculated in the present work (0.477÷0.723) fall within the range (0.38÷0.87) obtained in a global analysis by Monjo and Martin‐Vide (); they are similar to the ones computed in several studies on the whole of Europe (Cortesi et al, ) or at national and sub‐national scale in the Mediterranean basin (Italy—Coscarelli and Caloiero, ; Algeria—Benhamrouche et al, ; Spain—Serrano‐Notivoli et al, ). Moreover, these results agree with the ones obtained in several world countries such as the United States (Royé and Martin‐Vide, ), New Zealand (Caloiero, ) and Chile (Sarricolea et al, ).…”

Section: Resultsmentioning

confidence: 96%

Spatial and temporal variability of daily precipitation concentration in the Sardinia region (Italy)

Caloiero

Coscarelli

Gaudio

2019

Recent studies evidenced that extreme daily rainfall often increases in spite of a decrease of the total rainfall. For this reason, the analysis of daily precipitation concentration is an important issue in climate research and can be useful to evaluate risks linked to extreme rainfall events. In this paper, an analysis of the spatial and temporal variability of the daily precipitation concentration in the Sardinia region, the second largest island in the Mediterranean Sea, has been performed for the period 1922–2011 by applying the Concentration Index. First, the CI has been evaluated at annual and seasonal scale. Then, the coefficient of variation, and the 5th and 95th percentiles of the annual CI values were calculated and mapped as a set of descriptors of variability and extreme characterization of precipitation concentration across the study area. Finally, in order to evaluate the temporal evolution of the CI, a trend analysis has been also performed using the Mann–Kendall test. Results show CI values ranging from a minimum of 0.477 to a maximum of 0.723. Spatially, the region can be divided in two parts with opposite behaviours: the western side characterized by a more uniform temporal distribution of rainfall intensity and the eastern side with the most critical intensity and aggressiveness of rainfall. From a seasonal point of view, this spatial gradient was evidenced in winter, spring and autumn while summer showed a more homogeneous spatial distribution of CI. The spatial distribution of the coefficient of variation did not show any spatial gradient between the two sides of the region, both at annual and seasonal scale. As regards the trend analysis, a marked positive trend of the CI has been detected, thus indicating a tendency towards more intense and aggressive rainfall. Copyright © 2019 John Wiley & Sons, Ltd.