scholarly journals Monthly rain amounts at Fabra Observatory (Barcelona, NE Spain): fractal structure, autoregressive processes and correlation with monthly Western Mediterranean Oscillation index

2016 ◽  
Vol 37 (3) ◽  
pp. 1557-1577 ◽  
Author(s):  
X. Lana ◽  
A. Burgueño ◽  
M. D. Martínez ◽  
C. Serra
Keyword(s):  
Fractal Structure ◽  
Western Mediterranean ◽  
Autoregressive Processes ◽  
Mediterranean Oscillation ◽  
Ne Spain

scholarly journals Trends in rainfall erosivity in NE Spain at annual, seasonal and daily scales, 1955–2006

2012 ◽  
Vol 9 (5) ◽  
pp. 6285-6309 ◽  
Author(s):  
M. Angulo-Martínez ◽  
S. Beguería
Keyword(s):  
Soil Degradation ◽  
Bare Soil ◽  
Western Mediterranean ◽  
Rainfall Erosivity ◽  
Spatial And Temporal Variability ◽  
Major Mechanism ◽  
The North ◽  
Mediterranean Oscillation ◽  
The Impact ◽  
Ne Spain

Abstract. Rainsplash – the detachment and transport of soil particles by the impact of raindrops on a bare soil – is a major mechanism of soil degradation and erosion on semiarid areas and agricultural lands. Rainfall erosivity refers to the ability of precipitation to erode soil, and depends on the characteristics of the raindrops – size and velocity – and on the rainfall intensity and duration. Despite the relevance of rainfall erosivity for soil degradation prevention very few studies addressed its spatial and temporal variability. On this study the time variation of rainfall erosivity in the Ebro valley (NE Spain) is assessed for the period 1955–2006. The results show a general decrease in annual and seasonal rainfall erosivity, which is explained by a decrease of very intense rainfall events whilst the frequency of moderate and low events increased. This trend is related to prevailing positive conditions of the main atmospheric teleconnection indices affecting the West Mediterranean, i.e. the North Atlantic Oscillation (NAO), the Mediterranean Oscillation (MO) and the Western Mediterranean Oscillation (WeMO).

scholarly journals Trends in rainfall erosivity in NE Spain at annual, seasonal and daily scales, 1955–2006

2012 ◽  
Vol 16 (10) ◽  
pp. 3551-3559 ◽  
Author(s):  
M. Angulo-Martínez ◽  
S. Beguería
Keyword(s):  
Western Mediterranean ◽  
Rainfall Erosivity ◽  
Spatial And Temporal Variability ◽  
Rainfall Events ◽  
Atmospheric Teleconnection ◽  
Ebro Valley ◽  
The North ◽  
The North Atlantic Oscillation ◽  
Mediterranean Oscillation ◽  
Ne Spain

Abstract. Rainfall erosivity refers to the ability of precipitation to erode soil, and depends on characteristics such as its total volume, duration, and intensity and amount of energy released by raindrops. Despite the relevance of rainfall erosivity for soil degradation prevention, very few studies have addressed its spatial and temporal variability. In this study the time variation of rainfall erosivity in the Ebro Valley (NE Spain) is assessed for the period 1955–2006. The results show a general decrease in annual and seasonal rainfall erosivity, which is explained by a decrease of very intense rainfall events whilst the frequency of moderate and low events increased. This trend is related to prevailing positive conditions of the main atmospheric teleconnection indices affecting the West Mediterranean, i.e. the North Atlantic Oscillation (NAO), the Mediterranean Oscillation (MO) and the Western Mediterranean Oscillation (WeMO).

scholarly journals Non-stationary flood frequency analysis in continental Spanish rivers, using climate and reservoir indices as external covariates

2013 ◽  
Vol 17 (8) ◽  
pp. 3189-3203 ◽  
Author(s):  
J. López ◽  
F. Francés
Keyword(s):  
Frequency Analysis ◽  
Western Mediterranean ◽  
Flood Frequency ◽  
Additive Models ◽  
Stationary Time Series ◽  
Flood Frequency Analysis ◽  
Climate Indices ◽  
Flood Regime ◽  
Mediterranean Oscillation ◽  
The Impact

Abstract. Recent evidences of the impact of persistent modes of regional climate variability, coupled with the intensification of human activities, have led hydrologists to study flood regime without applying the hypothesis of stationarity. In this study, a framework for flood frequency analysis is developed on the basis of a tool that enables us to address the modelling of non-stationary time series, namely, the "generalized additive models for location, scale and shape" (GAMLSS). Two approaches to non-stationary modelling in GAMLSS were applied to the annual maximum flood records of 20 continental Spanish rivers. The results of the first approach, in which the parameters of the selected distributions were modelled as a function of time only, show the presence of clear non-stationarities in the flood regime. In a second approach, the parameters of the flood distributions are modelled as functions of climate indices (Arctic Oscillation, North Atlantic Oscillation, Mediterranean Oscillation and the Western Mediterranean Oscillation) and a reservoir index that is proposed in this paper. The results when incorporating external covariates in the study highlight the important role of interannual variability in low-frequency climate forcings when modelling the flood regime in continental Spanish rivers. Also, with this approach it is possible to properly introduce the impact on the flood regime of intensified reservoir regulation strategies. The inclusion of external covariates permits the use of these models as predictive tools. Finally, the application of non-stationary analysis shows that the differences between the non-stationary quantiles and their stationary equivalents may be important over long periods of time.

scholarly journals Rainfall regime trends at annual and monthly scales in Catalonia (NE Spain) and indications of CO2 emissions effects

2021 ◽  
Author(s):  
Xavier Lana ◽  
M. Carmen Casas-Castillo ◽  
Raül Rodríguez-Solà ◽  
Carina Serra ◽  
M. Dolors Martínez ◽  
...  
Keyword(s):  
Time Trends ◽  
Statistical Significance ◽  
Threshold Level ◽  
Western Mediterranean ◽  
Rainfall Regime ◽  
Rain Gauges ◽  
Dry Spells ◽  
Greenhouse Effects ◽  
Annual Scale ◽  
Ne Spain

AbstractThe pluviometric regime in the Western Mediterranean and concretely in Catalonia (NE Spain) is characterised by irregular amounts at monthly and annual scales, sometimes with copious short episodes causing floods and, conversely, sometimes with long dry spells exceeding 1 month length, depending on the chosen threshold level to define the dry episode. Taking advantage of a dense network of rain gauges, most of them with records length of 50–60 years and some others exceeding 85 years, the evolution of these monthly and annual amounts is quantified by means of their time trends, statistical significance and several irregularity parameters. In agreement with the evolution of the CO2 emissions into the atmosphere and the increasing concentration, in parts per million (ppm), of this greenhouse gas, different time trends at annual scale have been detected up to approximately years 1960–1970 in comparison with the interval 1960–1970 to nowadays. Consequently, besides the greenhouse effects on the temperature regime, the influence on the pluviometric regime could not be negligible. Graphical abstract

scholarly journals Non-stationary flood frequency analysis in continental Spanish rivers, using climate and reservoir indices as external covariates

2013 ◽  
Vol 10 (3) ◽  
pp. 3103-3142 ◽  
Author(s):  
J. López ◽  
F. Francés
Keyword(s):  
Frequency Analysis ◽  
Western Mediterranean ◽  
Flood Frequency ◽  
Additive Models ◽  
Stationary Time Series ◽  
Flood Frequency Analysis ◽  
Climate Indices ◽  
Flood Regime ◽  
Mediterranean Oscillation ◽  
The Impact

Abstract. Recent evidences of the impact of persistent modes of regional climate variability, coupled with the intensification of human activities, have led hydrologists to study flood regime without applying the hypothesis of stationarity. In this study, a framework for flood frequency analysis is developed on the basis of a tool that enables us to address the modelling of non-stationary time series, namely, the "generalized additive models for location, scale and shape" (GAMLSS). Two approaches to non-stationary modelling in GAMLSS were applied to the annual maximum flood records of 20 continental Spanish rivers. The results of the first approach, in which the parameters of the selected distributions were modeled as a function of time only, show the presence of clear non-stationarities in the flood regime. In a second approach, the parameters of the distributions are modeled as functions of climate indices (Arctic Oscillation, North Atlantic Oscillation, Mediterranean Oscillation and the Western Mediterranean Oscillation) and a reservoir index that is proposed in this paper. The results when incorporating external covariates in the study highlight the important role of interannual variability in low-frequency climate forcings when modelling the flood regime in continental Spanish rivers. Also, with this approach is possible to properly introduce the impact on the flood regime of intensified reservoir regulation strategies and to be used as predictive tools. Application of non-stationary analysis shows that the differences between the quantiles obtained and their stationary equivalents may be important over long periods of time.

Fractal structure and predictive strategy of the daily extreme temperature residuals at Fabra Observatory (NE Spain, years 1917–2005)

2014 ◽  
Vol 121 (1-2) ◽  
pp. 225-241 ◽  
Author(s):  
X. Lana ◽  
A. Burgueño ◽  
C. Serra ◽  
M. D. Martínez
Keyword(s):  
Fractal Structure ◽  
Extreme Temperature ◽  
Ne Spain

scholarly journals Lateglacial and Holocene palaeohydrology in the western Mediterranean region: The Lake Estanya record (NE Spain)

2009 ◽  
Vol 28 (25-26) ◽  
pp. 2582-2599 ◽  
Author(s):  
Mario Morellón ◽  
Blas Valero-Garcés ◽  
Teresa Vegas-Vilarrúbia ◽  
Penélope González-Sampériz ◽  
Óscar Romero ◽  
...  
Keyword(s):  
Mediterranean Region ◽  
Western Mediterranean ◽  
Ne Spain

scholarly journals Intra-annual variability of the Western Mediterranean Oscillation (WeMO) and occurrence of extreme torrential rainfall in Catalonia (NE Iberia)

2019 ◽  
Author(s):  
Joan Albert Lopez-Bustins ◽  
Laia Arbiol-Roca ◽  
Javier Martin-Vide ◽  
Antoni Barrera-Escoda ◽  
Marc Prohom
Keyword(s):  
Climate Change ◽  
Mediterranean Region ◽  
Western Mediterranean ◽  
Sensitive Area ◽  
Weather Extremes ◽  
Late Autumn ◽  
Annual Variability ◽  
Torrential Rainfall ◽  
Mediterranean Oscillation

Abstract. In previous studies the Western Mediterranean Oscillation index (WeMOi) at daily resolution has proven to constitute an effective tool for analysing the occurrence of episodes of torrential rainfall over eastern Spain. The Western Mediterranean region is therefore a very sensitive area, since climate change can enhance these weather extremes. In the present study we selected the extreme torrential episodes (≥ 200 mm in 24 hours) that took place in Catalonia (NE Iberia) during the 1951–2016 study period (66 years). We computed daily WeMOi values and constructed WeMOi calendars. Our principal results reveal the occurrence of 50 episodes (0.8 cases per year), mainly concentrated in the autumn months. We inferred a threshold of WeMOi ≤ −2 to define an extreme negative WeMO phase at daily resolution. Most of the 50 episodes (60 %) in the study area occurred on days presenting an extreme negative WeMOi value. Specifically, the most negative WeMOi values are detected in autumn, during the second 10-day period of October (11th–20th), coinciding with the highest frequency of extreme torrential events. On comparing the subperiods, we observed a statistically significant decrease in WeMOi values in all months, particularly in late October, and in November and December. No changes in the frequency of these extreme torrential episodes were observed between both subperiods; in contrast, a displacement of the episodes is detected from early to late autumn.

scholarly journals Aircraft vertical profiles during summertime regional and Saharan dust scenarios over the north-western Mediterranean Basin: aerosol optical and physical properties

2020 ◽  
Author(s):  
Jesús Yus-Díez ◽  
Marina Ealo ◽  
Marco Pandolfi ◽  
Noemí Perez ◽  
Gloria Titos ◽  
...  
Keyword(s):  
Optical Properties ◽  
Vertical Distribution ◽  
Asymmetry Parameter ◽  
Mediterranean Basin ◽  
Western Mediterranean ◽  
Saharan Dust ◽  
Vertical Profiles ◽  
Measurement Campaign ◽  
Western Mediterranean Basin ◽  
Ne Spain

Abstract. Accurate measurements of the horizontal and vertical distribution of atmospheric aerosol particle optical properties are key for a better understanding of their impact on the climate. Here we present the results of a measurement campaign based on instrumented flights over NE Spain. We measured vertical profiles of size segregated atmospheric particulate matter (PM) mass concentrations and multi-wavelength scattering and absorption coefficients in the Western Mediterranean Basin (WMB). The campaign took place during typical summer conditions, characterized by the development of a vertical multi-layer structure, under both summer regional pollution episodes (REG) and Saharan dust events (SDE). REG patterns in the region form under high insolation and scarce precipitation in summer, favoring layering of highly-aged fine PM strata in the lower few km a.s.l. The REG scenario prevailed during the entire measurement campaign. Additionally, African dust outbreaks and plumes from North African wildfires influenced the study area. The vertical profiles of climate relevant intensive optical parameters such as single scattering albedo (SSA), asymmetry parameter (g), scattering, absorption and SSA Angstrom exponents (SAE, AAE, SSAAE), and PM mas scattering and absorption cross sections (MSC and MAE) were derived from the measurements. Moreover, we compared the aircraft measurements with those performed at two GAW/ACTRIS surface measurement stations located in NE Spain, namely: Montseny (MSY; regional background) and Montsec d'Ares (MSA; remote site). Airborne in-situ measurements and ceilometer ground-based remote measurements identified aerosol air masses at altitude up to more than 3.5 km a.s.l. The vertical profiles of the optical properties markedly changed according to the prevailing atmospheric scenarios. During SDE the SAE was low along the profiles, reaching values  2.0 and the asymmetry parameter g was rather low (0.5–0.6) due to the prevalence of fine PM which were characterized by an AAE close to 1.0 suggesting a fossil fuel combustion origin. During REG, some of the layers featured larger AAE (> 1.5), relatively low SSA at 525 nm ( 9 m2 g−1) and were associated to the influence of PM from wildfires. Overall, the SSA and MSC near the ground ranged around 0.85 and 3 m2 g−1, respectively and increased at higher altitudes, reaching values above 0.95 and up to 9 m2 g−1. The PM, MSC and MAE were on average larger during REG compared to SDE due to the larger scattering and absorption efficiency of fine PM compared with dust. The SSA and MSC had quite similar vertical profiles and often both increased with height indicating the progressive shift toward PM with larger scattering efficiency with altitude. This study contributes to our understanding of regional aerosol vertical distribution and optical properties in the WMB and the results will be useful for improving future climate projections and remote sensing/satellite retrieval algorithms.

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