Variability of Mediterranean aerosols properties at three regional background sites in the western Mediterranean Basin

Author(s):  
Michaël Sicard ◽  
Julien Totems ◽  
Rubén Barragan ◽  
François Dulac ◽  
Marc Mallet ◽  
...  
2016 ◽  
Author(s):  
M. Sicard ◽  
R. Barragan ◽  
F. Dulac ◽  
L. Alados-Arboledas ◽  
M. Mallet

Abstract. In the framework of the ChArMEx (the Chemistry-Aerosol Mediterranean Experiment, http://charmex.lsce.ipsl.fr/) program, the seasonal variability of the aerosol optical, microphysical and radiative properties is examined in two regional background insular sites in the western Mediterranean Basin (WMB): Ersa (Corsica Island, France) and Palma de Mallorca (Mallorca Island, Spain). A third site in Alborán (Alborán Island, Spain) with only a few months of data is considered for exploring the possible Northeast–Southwest (NE–SW) gradient of the aforementioned aerosol properties. The dataset is exclusively composed of AERONET (Aerosol Robotic Network; http://aeronet.gsfc.nasa.gov/) products during a four-year period (2011–2014). AERONET fluxes are validated with ground- and satellite-based flux measurements. To the best of our knowledge this is the first time that AERONET fluxes are validated at the top of the atmosphere. Products such as the aerosol optical depth (AOD), the fraction fine mode to total AOD, the particle size distribution, the sphericity, the radiative forcing and the radiative forcing efficiency show a clear annual cycle. The main drivers of the observed annual cycles are mineral dust outbreaks in summer and the transport of European continental aerosols in spring. A NE–SW gradient is observed on 6 parameters (3 extensive and 3 intensive) out of the 18 discussed in the paper. The NE–SW gradient of the AOD, the Ångström exponent, the coarse mode volume concentration, the sphericity and the radiative forcing at the surface are related to mineral dust outbreaks, while the NE–SW gradient of the coarse mode volume median radius is related to the decreasing influence of European continental aerosols along the NE–SW axis. The fact that two thirds of the parameters discussed in the paper do not present a NE–SW gradient is partly explained by two relevant findings: (1) a homogeneous spatial distribution of the fine particle loads over the three sites in spite of the distances between the sites and the differences in local sources, and (2) low values and the absence of spectral dependency of the absorption found in the southwesternmost site.


2016 ◽  
Vol 16 (18) ◽  
pp. 12177-12203 ◽  
Author(s):  
Michaël Sicard ◽  
Rubén Barragan ◽  
François Dulac ◽  
Lucas Alados-Arboledas ◽  
Marc Mallet

Abstract. In the framework of the ChArMEx (the Chemistry-Aerosol Mediterranean Experiment; http://charmex.lsce.ipsl.fr/) program, the seasonal variability of the aerosol optical, microphysical and radiative properties derived from AERONET (Aerosol Robotic Network; http://aeronet.gsfc.nasa.gov/) is examined in two regional background insular sites in the western Mediterranean Basin: Ersa (Corsica Island, France) and Palma de Mallorca (Mallorca Island, Spain). A third site, Alborán (Alborán Island, Spain), with only a few months of data is considered for examining possible northeast–southwest (NE–SW) gradients of the aforementioned aerosol properties. The AERONET dataset is exclusively composed of level 2.0 inversion products available during the 5-year period 2011–2015. AERONET solar radiative fluxes are compared with ground- and satellite-based flux measurements. To the best of our knowledge this is the first time that AERONET fluxes are compared with measurements at the top of the atmosphere. Strong events (with an aerosol optical depth at 440 nm greater than 0.4) of long-range transport aerosols, one of the main drivers of the observed annual cycles and NE–SW gradients, are (1) mineral dust outbreaks predominant in spring and summer in the north and in summer in the south and (2) European pollution episodes predominant in autumn. A NE–SW gradient exists in the western Mediterranean Basin for the aerosol optical depth and especially its coarse-mode fraction, which all together produces a similar gradient for the aerosol direct radiative forcing. The aerosol fine mode is rather homogeneously distributed. Absorption properties are quite variable because of the many and different sources of anthropogenic particles in and around the western Mediterranean Basin: North African and European urban areas, the Iberian and Italian peninsulas, most forest fires and ship emissions. As a result, the aerosol direct forcing efficiency, more dependent to absorption than the absolute forcing, has no marked gradient.


2001 ◽  
Vol 65 (6) ◽  
pp. 537-548 ◽  
Author(s):  
M. P. GIRALDO ◽  
E. ESTEBAN ◽  
M. P. ALUJA ◽  
R. M. NOGUES ◽  
CH. BACKES-DURO ◽  
...  

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 678
Author(s):  
Kamel Atrouz ◽  
Ratiba Bousba ◽  
Francesco Paolo Marra ◽  
Annalisa Marchese ◽  
Francesca Luisa Conforti ◽  
...  

Olive tree with its main final product, olive oil, is an important element of Mediterranean history, considered the emblematic fruit of a civilization. Despite its wide diffusion and economic and cultural importance, its evolutionary and phylogenetic history is still difficult to clarify. As part of the Mediterranean basin, Algeria was indicated as a secondary diversification center. However, genetic characterization studies from Maghreb area, are currently underrepresented. In this context, we characterized 119 endemic Algerian accessions by using 12 microsatellite markers with the main goal to evaluate the genetic diversity and population structure. In order to provide new insights about the history of olive diversification events in the Central-Western Mediterranean basin, we included and analyzed a sample of 103 Italian accessions from Sicily and, a set of molecular profiles of cultivars from the Central-Western Mediterranean area. The phylogenetic investigation let us to evaluate genetic relationships among Central-Mediterranean basin olive germplasm, highlight new synonymy cases to support the importance of vegetative propagation in the cultivated olive diffusion and consolidate the hypothesis of more recent admixture events occurrence. This work provided new information about Algerian germplasm biodiversity and contributed to clarify olive diversification process.


1907 ◽  
Vol 4 (4) ◽  
pp. 157-165 ◽  
Author(s):  
T. Crook

In a paper read recently at a meeting of the Geological Society, Dr. Washington proposes to treat certain basalts of the Western Mediterranean basin as constituting “a hitherto unrecognised petro-graphic province, or comagmatic region, one of the most salient characters of which is the presence of salfemanes (basalts) that contain remarkably high amounts of titanium.”


Zootaxa ◽  
2020 ◽  
Vol 4759 (4) ◽  
pp. 597-599 ◽  
Author(s):  
CHRISTOPHE DUFRESNES ◽  
PIERRE-ANDRÉ CROCHET

Mediterranean tree frogs, Hyla gr. meridionalis Boettger, 1874 (Anura: Hylidae) are widespread around the Western Mediterranean Basin, where they naturally occur across the Maghreb (Morocco, Algeria, Tunisia). Individuals of diverse Moroccan origins have been introduced and have expanded throughout the Iberian Peninsula, southern France and northern Italy (Liguria), but also on the Canary and Balearic archipelagos (Recuero et al. 2007; Dufresnes et al. 2019). Early molecular studies uncovered several mitochondrial lineages and suggested a major cryptic diversification within this taxon, with Tunisian and eastern Algerian (Numidia) populations carrying deeply divergent haplotypes compared with the rest of the range (Recuero et al. 2007; Stöck et al. 2008; Stöck et al. 2012). While intron markers showed little differentiation (Stöck et al. 2008; Stöck et al. 2012), genome-wide data obtained from RAD-sequencing have supported the deep split suspected from mtDNA (Dufresnes et al. 2018). 


2018 ◽  
Vol 18 (10) ◽  
pp. 7287-7312 ◽  
Author(s):  
Arineh Cholakian ◽  
Matthias Beekmann ◽  
Augustin Colette ◽  
Isabelle Coll ◽  
Guillaume Siour ◽  
...  

Abstract. The simulation of fine organic aerosols with CTMs (chemistry–transport models) in the western Mediterranean basin has not been studied until recently. The ChArMEx (the Chemistry-Aerosol Mediterranean Experiment) SOP 1b (Special Observation Period 1b) intensive field campaign in summer of 2013 gathered a large and comprehensive data set of observations, allowing the study of different aspects of the Mediterranean atmosphere including the formation of organic aerosols (OAs) in 3-D models. In this study, we used the CHIMERE CTM to perform simulations for the duration of the SAFMED (Secondary Aerosol Formation in the MEDiterranean) period (July to August 2013) of this campaign. In particular, we evaluated four schemes for the simulation of OA, including the CHIMERE standard scheme, the VBS (volatility basis set) standard scheme with two parameterizations including aging of biogenic secondary OA, and a modified version of the VBS scheme which includes fragmentation and formation of nonvolatile OA. The results from these four schemes are compared to observations at two stations in the western Mediterranean basin, located on Ersa, Cap Corse (Corsica, France), and at Cap Es Pinar (Mallorca, Spain). These observations include OA mass concentration, PMF (positive matrix factorization) results of different OA fractions, and 14C observations showing the fossil or nonfossil origins of carbonaceous particles. Because of the complex orography of the Ersa site, an original method for calculating an orographic representativeness error (ORE) has been developed. It is concluded that the modified VBS scheme is close to observations in all three aspects mentioned above; the standard VBS scheme without BSOA (biogenic secondary organic aerosol) aging also has a satisfactory performance in simulating the mass concentration of OA, but not for the source origin analysis comparisons. In addition, the OA sources over the western Mediterranean basin are explored. OA shows a major biogenic origin, especially at several hundred meters height from the surface; however over the Gulf of Genoa near the surface, the anthropogenic origin is of similar importance. A general assessment of other species was performed to evaluate the robustness of the simulations for this particular domain before evaluating OA simulation schemes. It is also shown that the Cap Corse site presents important orographic complexity, which makes comparison between model simulations and observations difficult. A method was designed to estimate an orographic representativeness error for species measured at Ersa and yields an uncertainty of between 50 and 85 % for primary pollutants, and around 2–10 % for secondary species.


Forests ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 1054 ◽  
Author(s):  
Rodrigo Balaguer-Romano ◽  
Rubén Díaz-Sierra ◽  
Javier Madrigal ◽  
Jordi Voltas ◽  
Víctor Resco de Dios

Research Highlights: Pre-programmed cell death in old Aleppo pine needles leads to low moisture contents in the forest canopy in July, the time when fire activity nears its peak in the Western Mediterranean Basin. Here, we show, for the first time, that such needle senescence may increase fire behavior and thus is a potential mechanism explaining why the bulk of the annual burned area in the region occurs in early summer. Background and Objectives: The brunt of the fire season in the Western Mediterranean Basin occurs at the beginning of July, when live fuel moisture content is near its maximum. Here, we test whether a potential explanation to this conundrum lies in Aleppo pine needle senescence, a result of pre-programmed cell death in 3-years-old needles, which typically occurs in the weeks preceding the peak in the burned area. Our objective was to simulate the effects of needle senescence on fire behavior. Materials and Methods: We simulated the effects of needle senescence on canopy moisture and structure. Fire behavior was simulated across different phenological scenarios and for two highly contrasting Aleppo pine stand structures, a forest, and a shrubland. Wildfire behavior simulations were done with BehavePlus6 across a wide range of wind speeds and of dead fine surface fuel moistures. Results: The transition from surface to passive crown fire occurred at lower wind speeds under simulated needle senescence in the forest and in the shrubland. Transitions to active crown fire only occurred in the shrubland under needle senescence. Maximum fire intensity and severity were always recorded in the needle senescence scenario. Conclusions: Aleppo pine needle senescence may enhance the probability of crown fire development at the onset of the fire season, and it could partly explain the concentration of fire activity in early July in the Western Mediterranean Basin.


Check List ◽  
2019 ◽  
Vol 15 (6) ◽  
pp. 1077-1081 ◽  
Author(s):  
Graham J. Holloway ◽  
Dimitrios E. Bakaloudis

Anthrenus dorsatus Mulsant & Rey, 1868 has been recorded from North Africa, Malta, and Iberia. During a recent visit to Thessaloniki, Greece, several Anthrenus species were collected, including A. dorsatus. The previously known distribution of A. dorsatus suggested that this species was restricted to the western Mediterranean basin, possibly with a coastal bias. This record extends the known range of A. dorsatus farther east and providing more evidence of range expansion in the pimpinellae species group across Europe, possibly driven by global climate change.


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