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

Spatio Temporal Variability of Rainfall Across Western Libya from 1979 to 2009

2020 ◽  
Vol 6 (3) ◽  
pp. 235-244
Author(s):  
Ali Salem Eddenjal
Keyword(s):  
Time Series ◽  
Rainfall Variability ◽  
Statistical Significance ◽  
Regional Scale ◽  
Policy Makers ◽  
Rain Gauges ◽  
Spatio Temporal ◽  
Annual Scale ◽  
Increasing Trends ◽  
The Impact

Aims: To understand the links between climate variability and hydrology in western Libya. Background: This study represents the first comprehensive assessment of rainfall variability in western Libya at a regional scale. Objective: To assess temporal and spatial variability of rainfall in western Libya, based on data (1979-2009) from 16 rain gauges. Methods: The non-parametric Mann-Kendall method and Sen’s slop estimator were used to define changes in rainfall series and their statistical significance. Results: Coastal and mountainous time series showed decreasing trends at the annual, autumn, and spring scales, with very few exceptions. Notably, winter showed increasing trends, with the significant values of 1.94 and 0.88 mm/year at Sirt and Nalut, respectively. Desert stations showed increasing trends, especially at the annual scale, with the greatest significant increase on the order of 1.19 mm/year in Ghadames. For the regional rainfall trend analysis, annual, spring and autumn rainfalls decreased in the coastal and mountainous zones, with the highest significant decrease of 1.94 mm/year. Again, winter rainfall showed increasing trend over the whole study domain. Conclusion: Although most time series showed a tendency towards more drier conditions, most of the detected trends were statistically non-significant. This study will provide guidance for policy makers in their future planning to mitigate the impact of drought.

scholarly journals Multifractal structure of the monthly rainfall regime in Catalonia (NE Spain): Evaluation of the non-linear structural complexity

2020 ◽  
Vol 30 (7) ◽  
pp. 073117 ◽  
Author(s):  
X. Lana ◽  
R. Rodríguez-Solà ◽  
M. D. Martínez ◽  
M. C. Casas-Castillo ◽  
C. Serra ◽  
...  
Keyword(s):  
Structural Complexity ◽  
Monthly Rainfall ◽  
Rainfall Regime ◽  
Non Linear ◽  
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 Regiões pluviométricas homogêneas e a erosividade das chuvas na unidade hidrográfica Pirapó, Paranapanema III e IV-Paraná / Homogeneous rainfall regions and rainfall erosivity in the hydrographic unit Pirapó, Paranapanema III and IV hydrographic (...)

2016 ◽  
Vol 26 (46) ◽  
pp. 507 ◽  
Author(s):  
Paulo Miguel De Bodas Terassi ◽  
Hélio Silveira ◽  
Carlos Henrique Da Graça
Keyword(s):  
Euclidean Distance ◽  
Rainfall Erosivity ◽  
Proximity Measure ◽  
Temporal Segmentation ◽  
Rain Gauges ◽  
Monthly Distribution ◽  
Erosivity Index ◽  
Weather Stations ◽  
Annual Scale ◽  
The Relationship

<p>O presente trabalho objetiva definir regiões pluviométricas homogêneas e investigar a relação entre o regime pluviométrico e o potencial da erosividade para a unidade hidrográfica Pirapó, Paranapanema III e IV - Paraná. Foram obtidos os dados de pluviosidade de trinta e cinco postos pluviométricos do Instituto das Águas do Paraná e de cinco estações meteorológicas do Instituto Agronômico do Paraná (IAPAR), Instituto Nacional de Meteorologia (INMET) e Sistema Meteorológico do Paraná (SIMEPAR), trabalhados com o segmento temporal de 1976 a 2012. O índice de erosividade da chuva utilizado foi calculado a partir da equação apresentada por Rufino, Biscaia e Merten (1993) para o estado do Paraná. Definiu-se que o método de agrupamento mais adequado é o método aglomerativo de Ward, tendo como medida de proximidade a distância euclidiana. A área de estudo apresenta uma variação espacial da pluviosidade que mostra a influência da orografia principalmente para a distribuição espacial na escala anual, enquanto que a localização dos grupos demonstra uma maior associação à dinâmica atmosférica, conforme consultado pela literatura, para a compreensão da distribuição mensal das chuvas. Sobretudo, a delimitação dos grupos pluviométricos homogêneos permitiu compreender a relação entre o relevo, as alturas pluviométricas e o potencial erosivo das chuvas.</p><p><strong>Palavras-chave</strong>: agrupamento, pluviosidade, potencial erosivo, bacia hidrográfica.</p><p> </p><p>Abstract</p><p>This paper aims to define homogeneous rainfall regions and to investigate the relationship between rainfall and the potential erosivity for Pirapó, Paranapanema III and IV hydrographic unit - Paraná. The rainfall data was collected from thirty five rain gauges at Paraná Water Institute and from five weather stations at Paraná Agronomy Institute (IAPAR), National Weather Institute (INMET) and Paraná Meteorological System (SIMEPAR) and were processed within the temporal segmentation 1976 to 2012. The erosivity index rain used was calculated from the equation presented by Rufino, Biscaia and Merten (1993) for the Paraná State. It was defined that the most appropriate clustering method is the agglomerative method of Ward, with the proximity measure the Euclidean distance. The study area presents a spatial variation of rainfall that shows the orography influence mainly to the spatial distribution in the annual scale, while the location of groups shows a greater association with the atmospheric dynamics, as referred in the literature, for understanding the monthly distribution of rainfall. Above all, the delimitation of homogeneous rainfall groups allowed to understand the relationship between relief, the rain heights and the erosive potential of rainfall.</p><p><strong>Keywords</strong>: clustering, rainfall, erosive potential, watershed.</p>

scholarly journals Assimilation of wind data from airborne Doppler cloud-profiling radar in a kilometre-scale NWP system

2018 ◽  
Author(s):  
Mary Borderies ◽  
Olivier Caumont ◽  
Julien Delanoë ◽  
Véronique Ducrocq ◽  
Nadia Fourrié
Keyword(s):  
Positive Impact ◽  
Heavy Precipitation ◽  
Mediterranean Area ◽  
Western Mediterranean ◽  
Wind Data ◽  
Heavy Rainfall Event ◽  
Rain Gauges ◽  
The North ◽  
W Band ◽  
The Impact

Abstract. The article reports on the impact of the assimilation of wind vertical profile data in a kilometre-scale NWP system on predicting heavy precipitation events in the north-western Mediterranean area. The data collected in diverse conditions by the airborne W-band radar RASTA (Radar Airborne System Tool for Atmosphere) during a 45-day period are assimilated in the 3-h 3DVar assimilation system of AROME. The impact of the length of the assimilation window is investigated. The data assimilation experiments are performed for a heavy rainfall event, which occurred over south-eastern France on 26 September 2012 (IOP7a), and over a 45-day cycled period. During IOP7a, results indicate that the quality of the rainfall accumulation forecasts increases with the length of the assimilation window. By contrast, on the 45-day period, the best scores against rain gauges measurements are reached with a 1 hour assimilation window, which recommends to use observations with a small period centred on the assimilation time. The positive impact of the assimilation of RASTA wind data is particularly evidenced for the IOP7a case since results indicate an improvement in the predicted wind at short term ranges (2 hours and 3 hours) and in the 12-hour precipitation forecasts. However, on the 45-day cycled period, the comparison against other assimilated observations shows an overall neutral impact. Results are still encouraging since a slight positive improvement in the 6-, 9- and 12-hour precipitation forecasts of heavier rainfall was demonstrated.

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.

scholarly journals Comparison of Post-fire Patterns in Brazilian Savanna and Tropical Forest from Remote Sensing Time Series

2020 ◽  
Vol 9 (11) ◽  
pp. 659
Author(s):  
Níckolas Castro Santana ◽  
Osmar Abílio de Carvalho Júnior ◽  
Roberto Arnaldo Trancoso Gomes ◽  
Renato Fontes Guimarães
Keyword(s):  
Remote Sensing ◽  
Time Series ◽  
Surface Temperature ◽  
Time Trends ◽  
Vegetation Index ◽  
Fire Regime ◽  
Statistical Significance ◽  
Terrestrial Vegetation ◽  
Fire Recurrence ◽  
Sensing Time

Monitoring of fire-related changes is essential to understand vegetation dynamics in the medium and long term. Remote sensing time series allows estimating biophysical variables of terrestrial vegetation and interference by extreme fires. This research evaluated fire recurrence in the Amazon and Cerrado regions, using Moderate Resolution Imaging Spectroradiometer (MODIS) albedo time series, enhanced vegetation index (EVI), gross primary productivity (GPP), and surface temperature. The annual aggregated time series (AAT) method recognized each pixel’s slope trend in the 2001–2016 period and its statistical significance. A comparison of time trends of EVI, GPP, and surface temperature with total fire recurrence indicates that time trends in vegetation are highly affected by high fire recurrence scenarios (R2 between 0.52 and 0.90). The fire recurrence and the albedo’s persistent changes do not have a consistent relationship. Areas with the biggest evaluated changes may increase up to 0.25 Kelvin/Year at surface temperature and decrease up to −0.012 EVI/year in vegetation index. Although savannas are resistant to low severity fires, fire regime and forest structure changes tend to make vegetation more vulnerable to wildfires, reducing their regeneration capacity. In the Amazon area, protection of forests in conservation units and indigenous lands helped in the low occurrence of fires in these sensitive areas, resulting in positive vegetation index trends.

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