scholarly journals Fuel loading and flammability in the Mediterranean Basin woody species with different post-fire regenerative strategies

2010 ◽  
Vol 19 (6) ◽  
pp. 783 ◽  
Author(s):  
S. Saura-Mas ◽  
S. Paula ◽  
J. G. Pausas ◽  
F. Lloret

The flammability and combustibility of plant communities are determined by species features related to growth-form, structure and physiology. In some ecosystems, such as the Mediterranean ones, these characteristics may contribute to the existence of fire-prone species. We measured several parameters associated with the flammability and fuel loading of dominant woody species with different post-fire regenerative strategies (seeders and non-seeders) in shrublands in the western Mediterranean Basin. Overall, seeder species show lower fuel load but are more prone to burning owing to a higher dead-to-live fuel ratio, live fine-fuel proportion and dead fine-fuel proportion. Moreover, they burst into flame at lower temperatures than non-seeders. In the Mediterranean Basin, most seeder species emerged mainly during the Quaternary, under a highly fluctuating Mediterranean climate and during recurrent fires. We propose that properties related to the combustibility and flammability of seeders may be the result of selective pressures associated with both fire and climate. These results suggest that ecosystems dominated by seeder species are more susceptible to fire risk than those dominated by non-seeder species in the Mediterranean Basin. Therefore, the proportion of these types of species resulting from previous fire or management history is likely to determine the characteristics of future fire events.

2013 ◽  
Vol 13 (6) ◽  
pp. 16247-16299 ◽  
Author(s):  
A. Gkikas ◽  
N. Hatzianastassiou ◽  
N. Mihalopoulos ◽  
V. Katsoulis ◽  
S. Kazadzis ◽  
...  

Abstract. The regime of desert dust (DD) episodes over the broader Mediterranean basin is studied for the period 2000–2007. The novelty of this work lies in its complete spatial coverage of the region. An objective and dynamic algorithm has been set up, which uses daily measurements of various aerosol optical properties taken by different satellite databases, enabling the identification of DD episodes and their classification into strong and extreme ones. The algorithm's performance was tested against surface based (in situ) Particulate Matter (PM) and (columnar) sun-photometric AERONET measurements from stations distributed across the Mediterranean. The comparisons have shown the reasonable ability of the algorithm to detect the DD episodes taking place within the study region. The largest disagreements with PM data were found in summer and western Mediterranean, when African dust transport has a great vertical extent that cannot be satisfactorily captured by surface measurements. According to our results, DD episodes in the Mediterranean basin are quite frequent (up to 11.4 episodes/year) while there is a significant spatial and temporal variability in their frequency of occurrence and their intensity. Strong episodes occur more frequently in the western Mediterranean basin whilst extreme ones appear more frequently over central Mediterranean Sea areas. Apart from this longitudinal variation, there is a predominant latitudinal variability in both frequency and intensity, with decreasing values from south to north. A significant seasonal variation was also found for the frequency of DD episodes, with both strong and extreme episodes being more frequent during summer in the western Mediterranean basin, but during spring in its central and eastern parts. In most cases (>85%) the Mediterranean dust episodes last a bit longer than a day, although their duration can reach 6 days for strong episodes and 4 days for extreme episodes. A noticeable year by year variability was also found, especially for the frequency of the episodes. The spatial and temporal patterns of Mediterranean DD episodes can be explained based on surface pressure and precipitation spatio-temporal distribution patterns over the study region, as well as by the year by year variability of North Atlantic Oscillation (NAO). In this context, a decreasing frequency of appearance of DD episodes over the Mediterranean basin has been revealed over the period 2000–2007, especially over land surfaces, in line with decreasing NAO Index over the same period. Our findings demonstrate the reasonable ability to detect desert dust outbreaks in the Mediterranean basin from satellites.


2020 ◽  
Vol 12 (13) ◽  
pp. 5383 ◽  
Author(s):  
Antonio Comi ◽  
Antonio Polimeni

The paper aims to investigate short sea shipping services as a competitive, sustainable freight transport system which is able to respond to economic, social and environmental needs. An assessment methodology is proposed which considers an aggregate discrete choice model, simulating the split between the competitive transport alternatives in the Mediterranean basin. The proposed methodology was used to assess the potential of short sea shipping (SSS) and the net benefits deriving from lower external costs in the north-western Mediterranean basin. Two future scenarios are considered: introduction of new SSS services as envisaged by current EU projects and plans, and the introduction of new SSS routes and an increase in frequencies of existing services. Significant results were obtained in terms of shifting freight traffic from the road network as well as external benefits.


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.


2015 ◽  
Vol 3 (6) ◽  
pp. 3687-3732 ◽  
Author(s):  
U. Dayan ◽  
K. M. Nissen ◽  
U. Ulbrich

Abstract. This review discusses published studies of heavy rainfall events over the Mediterranean Basin, combining them in a more general picture of the dynamic and thermodynamic factors and processes producing heavy rain storms. It distinguishes the Western and Eastern Mediterranean in order to point at specific regional peculiarities. The crucial moisture for developing intensive convection over these regions can be originated not only from the adjacent Mediterranean Sea but also from distant upwind sources. Transport from remote sources is usually in the mid-tropospheric layers and associated with specific features and patterns of the larger scale circulations. The synoptic systems (tropical and extra-tropical) accounting for most of the major extreme precipitation events and the coupling of circulation and extreme rainfall patterns are presented. Heavy rainfall over the Mediterranean Basin is caused at times in concert by several atmospheric processes working at different atmospheric scales, such as local convection, upper-level synoptic-scale troughs, and meso-scale convective systems. Under tropical air mass intrusions, convection generated by static instability seems to play a more important role than synoptic-scale vertical motions. Locally, the occurrence of torrential rains and their intensity is dependent on factors such as temperature profiles and implied instability, atmospheric moisture, and lower-level convergence.


2021 ◽  
pp. 1-26
Author(s):  
Joan Pinar Gil ◽  
Jaime Vizcaíno Sánchez

Abstract During the 6th and 7th c. CE, Carthago Spartaria (modern Cartagena) became one of the most important cities in the Byzantine province of Spania. Recent archaeological excavations at Cerro del Molinete have significantly increased our knowledge of the ancient city, enabling the exploration of an early Byzantine neighborhood built over the Roman Forum district. A cast bronze ewer of type Werner A2 was found in a pit dug over the temple that presided over the Forum. The associated materials, mainly pottery and glass vessels, are compatible with a deposition between 580/90 and 650/60 CE. This assemblage improves our understanding of the trade networks interconnecting the Mediterranean basin during the 6th and 7th c. CE. In this context, we argue that the unknown production center of the A2 ewers was located in the northern Adriatic, probably in Ravenna.


2021 ◽  
Author(s):  
Johannes Vogel

<p>The ecosystems of the Mediterranean Basin are particularly prone to climate change and related alterations in climatic anomalies. The seasonal timing of climatic anomalies is crucial for the assessment of the corresponding ecosystem impacts; however, the incorporation of seasonality is neglected in many studies. We quantify ecosystem vulnerability by investigating deviations of the climatic drivers temperature and soil moisture during phases of low ecosystem productivity for each month of the year over the period 1999 – 2019. The fraction of absorbed photosynthetically active radiation (FAPAR) is used as a proxy for ecosystem productivity. Air temperature is obtained from the reanalysis data set ERA5 Land and soil moisture and FAPAR satellite products are retrieved from ESA CCI and Copernicus Global Land Service, respectively. Our results show that Mediterranean ecosystems are vulnerable to three soil moisture regimes during the course of the year. A phase of vulnerability to hot and dry conditions during late spring to midsummer is followed by a period of vulnerability to cold and dry conditions in autumn. The third phase is characterized by cold and wet conditions coinciding with low ecosystem productivity in winter and early spring. These phases illustrate well the shift between a soil moisture-limited regime in summer and an energy-limited regime in winter in the Mediterranean Basin. Notably, the vulnerability to hot and dry conditions during the course of the year is prolonged by several months in the Eastern Mediterranean compared to the Western Mediterranean. Our approach facilitates a better understanding of ecosystem vulnerability at certain stages during the year and is easily transferable to other study areas and ecoclimatological variables.</p>


2015 ◽  
Vol 15 (11) ◽  
pp. 2525-2544 ◽  
Author(s):  
U. Dayan ◽  
K. Nissen ◽  
U. Ulbrich

Abstract. This review discusses published studies of heavy rainfall events over the Mediterranean Basin, combining them in a more general picture of the dynamic and thermodynamic factors and processes that produce heavy rain storms. It distinguishes the western and eastern Mediterranean in order to point out specific regional peculiarities. The crucial moisture for developing intensive convection over these regions can be originated not only from the adjacent Mediterranean Sea but also from distant upwind sources. Transport from remote sources is usually in the mid-tropospheric layers and associated with specific features and patterns of the larger-scale circulations. The synoptic systems (tropical and extratropical) that account for most of the major extreme precipitation events and the coupling of circulation and extreme rainfall patterns are presented. Heavy rainfall over the Mediterranean Basin is caused at times in concert by several atmospheric processes working at different atmospheric scales, such as local convection, upper synoptic-scale-level troughs, and mesoscale convective systems. Under tropical air-mass intrusions, convection generated by static instability seems to play a more important role than synoptic-scale vertical motions. Locally, the occurrence of torrential rains and their intensity is dependent on factors such as temperature profiles and implied instability, atmospheric moisture, and lower-level convergence.


2007 ◽  
Vol 16 (5) ◽  
pp. 633 ◽  
Author(s):  
G. Pellizzaro ◽  
P. Duce ◽  
A. Ventura ◽  
P. Zara

The objectives of the present study were (i) to describe the seasonal pattern of ignition delay (ID time) and moisture content of live fine fuel (LFMC) for eight common shrub species of the Western Mediterranean Basin, and (ii) to evaluate the relationships between LFMC and ignitability. The experiment was carried out in a shrubland area located in Sardinia, Italy. LFMC and time to ignition or ID time values were determined monthly or twice a month throughout the year. Ignitability was determined by laboratory tests. Meteorological data were also collected from a weather station located in the study area. Significant linear regression equations of ID time v. LFMC were found for most of the species, with R2 values ranging from 67 to 94%. In general, very low values of ID time were observed when LFMC ranged from 70 to 100%. In addition, two groups of species were identified, depending on seasonal changes of both LFMC and ID time (or ignitability): (i) species with LFMC not greater than 100% and high ignitability values all throughout the year, and (ii) species with large seasonal variability of LFMC and ignitability values that were low in winter and high in summer. Significant differences in ignitability among species were also observed.


2015 ◽  
Vol 15 (15) ◽  
pp. 21607-21669 ◽  
Author(s):  
C. Denjean ◽  
F. Cassola ◽  
A. Mazzino ◽  
S. Triquet ◽  
S. Chevaillier ◽  
...  

Abstract. This study presents in situ aircraft measurements of Saharan mineral dust transported over the western Mediterranean basin in June–July 2013 during the ChArMEx/ADRIMED (the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region) airborne campaign. Dust events differing in terms of source region (Algeria, Tunisia and Morocco), time of tranport (1–5 days) and height of transport were sampled. Mineral dust were transported above the marine boundary layer, which conversely was dominated by pollution and marine aerosols. The dust vertical structure was extremely variable and characterized by either a single layer or a more complex and stratified structure with layers originating from different source regions. Mixing of mineral dust with pollution particles was observed depending on the height of transport of the dust layers. Dust layers carried higher concentration of pollution particles at intermediate altitude (1–3 km) than at elevated altitude (> 3 km), resulting in scattering Angstrom exponent up to 2.2 within the intermediate altitude. However, the optical properties of the dust plumes remained practically unchanged with respect to values previously measured over source regions, regardless of the altitude. Moderate light absorption of the dust plumes was observed with values of aerosol single scattering albedo at 530 nm ranging from 0.90 to 1.00 ± 0.04. Concurrent calculations from the aerosol chemical composition revealed a negligible contribution of pollution particles to the absorption properties of the dust plumes that was due to a low contribution of refractory black carbon in regards to the fraction of dust and sulfate particles. This suggests that, even in the presence of moderate pollution, likely a persistent feature in the Mediterranean, the optical properties of the dust plumes could be assimilated to those of native dust in radiative transfer simulations, modeling studies and satellite retrievals over the Mediterranean. Measurements also showed that the coarse mode of mineral dust was conserved even after 5 days of transport in the Mediterranean, which contrasts with the gravitational depletion of large particles observed during the transport of dust plumes over the Atlantic. Simulations with the WRF mesoscale meteorological model highlighted a strong vertical turbulence within the dust layers that could prevent deposition of large particles during their atmospheric transport. This has important implications for the dust radiative effects due to surface dimming, atmospheric heating and cloud formation. The results presented here add to the observational dataset necessary for evaluating the role of mineral dust on the regional climate and rainfall patterns in the western Mediterranean basin.


2018 ◽  
Vol 99 (2) ◽  
pp. 361-380 ◽  
Author(s):  
Philippe Ricaud ◽  
Régina Zbinden ◽  
Valéry Catoire ◽  
Vanessa Brocchi ◽  
François Dulac ◽  
...  

Abstract The Gradient in Longitude of Atmospheric Constituents above the Mediterranean Basin (GLAM) airborne campaign was set up to investigate the summertime variability of gaseous pollutants, greenhouse gases, and aerosols between the western (∼3°E) and eastern (∼35°E) sections of the Mediterranean basin as well as how this connects with the impact of the Asian monsoon anticyclone on the eastern Mediterranean in the mid- to upper troposphere (∼5–10 km). GLAM falls within the framework of the Chemistry–Aerosol Mediterranean Experiment (ChArMEx) program. GLAM used the French Falcon-20 research aircraft to measure aerosols, humidity, and chemical compounds: ozone, carbon monoxide, methane, and carbon dioxide. GLAM took place between 6 and 10 August 2014, following a route from Toulouse (France) to Larnaca (Cyprus) and back again via Minorca (Spain), Lampedusa (Italy), and Heraklion (Crete, Greece). The aircraft flew at an altitude of 5 km on its outbound journey and 10 km on the return leg. GLAM also collected vertical profiles around the landing sites listed above. A combination of model outputs, chemical mapping analyses, and spaceborne and surface station measurements gathered prior to and during the campaign were used to interpret the in situ airborne measurements. The main outcome of this study is the impact of intercontinental transport on the longitudinal variability of pollutants, greenhouse gases, and aerosols at an altitude of 10 km. The eastern Mediterranean is affected by air masses from the Arabian Sea surface, and the western Mediterranean is impacted by air masses from North America (biomass burning) and West Africa (desert dust).


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