scholarly journals The regime of intense desert dust episodes in the Mediterranean based on contemporary satellite observations and ground measurements

2013 ◽  
Vol 13 (23) ◽  
pp. 12135-12154 ◽  
Author(s):  
A. Gkikas ◽  
N. Hatzianastassiou ◽  
N. Mihalopoulos ◽  
V. Katsoulis ◽  
S. Kazadzis ◽  
...  
Keyword(s):  
Mediterranean Basin ◽  
Western Mediterranean ◽  
Spatial And Temporal Variability ◽  
Central Mediterranean ◽  
Study Region ◽  
Dust Transport ◽  
Desert Dust ◽  
Western Mediterranean Basin ◽  
Spatial Coverage ◽  
The Mediterranean

Abstract. The regime of intense desert dust (DD) episodes over the broader Mediterranean Basin is studied for the period 2000–2007 at a complete spatial coverage. 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 (AErosol RObotic NETwork) 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 the western Mediterranean in summer, 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 yr−1), 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 on average, although their duration can reach six days for strong episodes and four days for extreme episodes. A noticeable year-to-year variability was also found, especially for the frequency of the episodes.

scholarly journals The regime of desert dust episodes in the Mediterranean based on contemporary satellite observations and ground measurements

2013 ◽  
Vol 13 (6) ◽  
pp. 16247-16299 ◽  
Author(s):  
A. Gkikas ◽  
N. Hatzianastassiou ◽  
N. Mihalopoulos ◽  
V. Katsoulis ◽  
S. Kazadzis ◽  
...  
Keyword(s):  
Mediterranean Basin ◽  
Western Mediterranean ◽  
Spatial And Temporal Variability ◽  
Central Mediterranean ◽  
Study Region ◽  
Desert Dust ◽  
Western Mediterranean Basin ◽  
Spatial Coverage ◽  
The Mediterranean ◽  
The Mediterranean Basin

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.

scholarly journals Algerian Olive Germplasm and Its Relationships with the Central-Western Mediterranean Varieties Contributes to Clarify Cultivated Olive Diversification

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 678
Author(s):  
Kamel Atrouz ◽  
Ratiba Bousba ◽  
Francesco Paolo Marra ◽  
Annalisa Marchese ◽  
Francesca Luisa Conforti ◽  
...  
Keyword(s):  
Mediterranean Basin ◽  
Genetic Relationships ◽  
Olive Tree ◽  
Mediterranean Area ◽  
Western Mediterranean ◽  
Central Mediterranean ◽  
Western Mediterranean Basin ◽  
New Information ◽  
Mediterranean History ◽  
New Synonymy

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.

scholarly journals Simulation of fine organic aerosols in the western Mediterranean area during the ChArMEx 2013 summer campaign

2018 ◽  
Vol 18 (10) ◽  
pp. 7287-7312 ◽  
Author(s):  
Arineh Cholakian ◽  
Matthias Beekmann ◽  
Augustin Colette ◽  
Isabelle Coll ◽  
Guillaume Siour ◽  
...  
Keyword(s):  
Mediterranean Basin ◽  
Mass Concentration ◽  
Organic Aerosols ◽  
Western Mediterranean ◽  
Basis Set ◽  
Aerosol Formation ◽  
Standard Scheme ◽  
Western Mediterranean Basin ◽  
The Mediterranean ◽  
Fine Organic

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.

scholarly journals North African dust transport toward the western Mediterranean basin: Atmospheric controls on dust source activation and transport pathways during June–July 2013

2016 ◽  
Author(s):  
Kerstin Schepanski ◽  
Marc Mallet ◽  
Bernd Heinold ◽  
Max Ulrich
Keyword(s):  
Atmospheric Circulation ◽  
Mediterranean Basin ◽  
Dust Emission ◽  
Western Mediterranean ◽  
North African ◽  
Atmospheric Dust ◽  
Dust Source ◽  
Dust Transport ◽  
The Mediterranean ◽  
Heat Low

Abstract. Dust transported from North African source region toward the Mediterranean basin and Europe is an ubiquitous phenomenon in the Mediterranean region. Winds formed by large-scale pressure gradients foster dust entrainment into the atmosphere over North African dust source regions and advection of dust downwind. The constellation of centers of high and low pressure determines wind speed and direction, and thus the chance for dust emission over Northern Africa and transport toward the Mediterranean. Here, we present characteristics of the atmospheric dust life-cycle determining dust transport toward the Mediterranean basin. Using the atmosphere-dust model COSMO-MUSCAT (COSMO: COnsortium for Small-scale MOdelling; MUSCAT: MUltiScale Chemistry Aerosol Transport Model), a complementary analysis of dust source activation, emission fluxes, transport pathways, and deposition rates is provided with focus on the ChArMEx (Chemistry-Aerosol Mediterranean Experiment) special observation period in June and July 2013. Modes of atmospheric circulation, identified from empirical orthogonal function (EOF) analysis of the geopotential height at 850 hPa are used for investigating the characteristics of the atmospheric dust life-cycle regarding the atmospheric circulation over the Mediterranean. Two different phases are identified from the first EOF, which in total are explaining 45 % of the variance. They are characterized by the propagation of the subtropical ridge into the Mediterranean basin, the position of the Saharan heat low and the predominance Iberian heat low and discussed illustrating a dipole pattern for enhanced (reduced) dust emission fluxes, stronger (weaker) meridional dust transport, and consequent increased (decreased) atmospheric dust concentrations and deposition fluxes. In case of a predominant high pressure zone over the western and central Mediterranean (positive phase), a hot spot in dust emission flux is evident over the Grand Erg Occidental and reduced level of atmospheric dust loading occurs over the western Mediterranean basin. The meridional transport in northward direction is reduced due to prevailing northerly winds. In case of a predominant heat low trough linking the Iberian and the Sahara heat low (negative phase), meridional dust transport toward the western Mediterranean is increased due to prevailing southerly winds resulting into an enhanced atmospheric dust loading over the western Mediterranean. Altogether, results form this study illustrate the relevance of knowing dust source location in concert with atmospheric circulation. The study elaborates the question on the variability of dust transport toward the Mediterranean and Europe in dependence on the atmospheric circulation as a driver for dust emission and a determinant for dust transport routes, exemplarily for the two-month period June to July 2013. Ultimately, outcomes from this study contribute to the understanding of the variance in dust transport into a populated region.

scholarly journals Mediterranean intense desert dust outbreaks and their vertical structure based on remote sensing data

2016 ◽  
Vol 16 (13) ◽  
pp. 8609-8642 ◽  
Author(s):  
Antonis Gkikas ◽  
Sara Basart ◽  
Nikos Hatzianastassiou ◽  
Eleni Marinou ◽  
Vassilis Amiridis ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Vertical Structure ◽  
Fine Fraction ◽  
Western Mediterranean ◽  
Dust Particles ◽  
Vertical Profiles ◽  
Study Region ◽  
Desert Dust ◽  
Modis Aod ◽  
The Mediterranean

Abstract. The main aim of the present study is to describe the vertical structure of the intense Mediterranean dust outbreaks, based on the use of satellite and surface-based retrievals/measurements. Strong and extreme desert dust (DD) episodes are identified at 1°  ×  1° spatial resolution, over the period March 2000–February 2013, through the implementation of an updated objective and dynamic algorithm. According to the algorithm, strong DD episodes occurring at a specific place correspond to cases in which the daily aerosol optical depth at 550 nm (AOD550 nm) exceeds or equals the long-term mean AOD550 nm (Mean) plus two standard deviations (SD), which is also smaller than Mean+4 × SD. Extreme DD episodes correspond to cases in which the daily AOD550 nm value equals or exceeds Mean+4 × SD. For the identification of DD episodes, additional optical properties (Ångström exponent, fine fraction, effective radius and aerosol index) derived by the MODIS-Terra & Aqua (also AOD retrievals), OMI-Aura and EP-TOMS databases are used as inputs. According to the algorithm using MODIS-Terra data, over the period March 2000–February 2013, strong DD episodes occur more frequently (up to 9.9 episodes year−1) over the western Mediterranean, while the corresponding frequencies for the extreme ones are smaller (up to 3.3 episodes year−1, central Mediterranean Sea). In contrast to their frequency, dust episodes are more intense (AODs up to 4.1), over the central and eastern Mediterranean Sea, off the northern African coasts. Slightly lower frequencies and higher intensities are found when the satellite algorithm operates based on MODIS-Aqua retrievals, for the period 2003–2012. The consistency of the algorithm is successfully tested through the application of an alternative methodology for the determination of DD episodes, which produced similar features of the episodes' frequency and intensity, with just slightly higher frequencies and lower intensities. The performance of the satellite algorithm is assessed against surface-based daily data from 109 sun-photometric (AERONET) and 22 PM10 stations. The agreement between AERONET and MODIS AOD is satisfactory (R = 0.505 − 0.750) and improves considerably when MODIS level 3 retrievals with higher sub-grid spatial representativeness and homogeneity are considered. Through the comparison against PM10 concentrations, it is found that the presence of dust is justified in all ground stations with success scores ranging from 68 to 97 %. However, poor agreement is evident between satellite and ground PM10 observations in the western parts of the Mediterranean, which is attributed to the desert dust outbreaks' vertical extension and the high altitude of dust presence. The CALIOP vertical profiles of pure and polluted dust observations and the associated total backscatter coefficient at 532 nm (β532 nm), indicate that dust particles are mainly detected between 0.5 and 6 km, though they can reach 8 km between the parallels 32 and 38° N in warm seasons. An increased number of CALIOP dust records at higher altitudes is observed with increased latitude, northwards to 40° N, revealing an ascending mode of the dust transport. However, the overall intensity of DD episodes is maximum (up to 0.006 km−1 sr−1) below 2 km and at the southern parts of the study region (30–34° N). Additionally, the average thickness of dust layers gradually decreases from 4 to 2 km, moving from south to north. In spring, dust layers of moderate-to-high β532 nm values ( ∼  0.004 km−1 sr−1) are detected over the Mediterranean (35–42° N), extending from 2 to 4 km. Over the western Mediterranean, dust layers are observed between 2 and 6 km, while their base height is decreased down to 0.5 km for increasing longitudes underlying the role of topography and thermal convection. The vertical profiles of CALIOP β532 nm confirm the multilayered structure of the Mediterranean desert dust outbreaks on both annual and seasonal bases, with several dust layers of variable geometrical characteristics and intensities. A detailed analysis of the vertical structure of specific DD episodes using CALIOP profiles reveals that the consideration of the dust vertical structure is necessary when attempting comparisons between columnar MODIS AOD retrievals and ground PM10 concentrations.

scholarly journals Size distribution and optical properties of mineral dust aerosols transported in the western Mediterranean

2015 ◽  
Vol 15 (15) ◽  
pp. 21607-21669 ◽  
Author(s):  
C. Denjean ◽  
F. Cassola ◽  
A. Mazzino ◽  
S. Triquet ◽  
S. Chevaillier ◽  
...  
Keyword(s):  
Optical Properties ◽  
Mediterranean Basin ◽  
Mineral Dust ◽  
Regional Climate ◽  
Source Region ◽  
Western Mediterranean ◽  
Source Regions ◽  
Western Mediterranean Basin ◽  
Large Particles ◽  
The Mediterranean

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.

scholarly journals WRF-Chem model simulations of a dust outbreak over the Central Mediterranean and comparison with multi-sensor desert dust observations

2016 ◽  
Author(s):  
Umberto Rizza ◽  
Francesca Barnaba ◽  
Mario Marcello Miglietta ◽  
Gian Paolo Gobbi ◽  
Cristina Mangia ◽  
...  
Keyword(s):  
Wrf Model ◽  
Vertical Displacement ◽  
Western Mediterranean ◽  
Saharan Dust ◽  
Central Mediterranean ◽  
Desert Dust ◽  
Pm10 And Pm2.5 ◽  
Modis Aod ◽  
The Mediterranean ◽  
Good Agreement

Abstract. In this study, the Weather Research and Forecasting (WRF) Model with online coupled chemistry (WRF-Chem) is applied to simulate an intense Saharan dust outbreak event that took place over the Mediterranean in May 2014. The dust outbreak was generated in correspondence with an omega-like pressure configuration associated with a cyclogenesis in the Atlantic coasts of Spain. This pattern has been recognized as one of the three major cyclogenesis situations responsible for the transport of Saharan dust towards the Central and Western Mediterranean. In fact, in the case investigated here, a cyclone near the Atlantic coasts of Spain is responsible for strong westerly Atlantic winds (about 20 m s−1) reaching the northern Sahara and leading to the lifting of mineral dust. The northward transport is made possible by a ridge over the central Mediterranean associated with the omega-like pressure configuration. WRF-Chem simulations are able to reproduce the synoptic meteorological conditions and the transport outline of the dust outbreak that was in fact characterized by multiple, superimposed dust impulses. The model performances in reproducing the atmospheric desert dust load were evaluated using a multi-platform observational dataset of aerosol and desert dust properties, including optical properties from satellite and ground-based sun-photometers and lidars, plus in situ PM10 data. This comparison allowed us to investigate the model ability in reproducing both the horizontal and the vertical displacement of the dust plume, and its evolution in time. Results show a good agreement between the model and the AERONET-AOD in six sites in the Mediterranean. Comparison with the MODIS-AOD retrieval shows that WRF-Chem satisfactorily resolves the arrival, the time evolution and the horizontal pattern of the dust storm over Central Mediterranean. Comparison with lidar data confirms the desert dust advection to occur in several, superimposed ‘pulses’, as simulated by the model. In most cases the desert dust is shown to arrive above the PBL and then to descend and mix with the local aerosols within it. The vertical displacement of the dust was in good agreement with the lidar soundings with a mean discrepancy along the aerosol extinction of about 40–60 %. The model-measurements comparison for the PM10 and PM2.5 shows a good temporal matching, although there is a clear overestimation of PM10 and PM2.5, of the order of 70 % during the dust peak. This tendency is reduced or even inverted in weak-dust or no-dust conditions, in which model and measured PM10 and PM2.5 are within 30 % and 10–60 %, respectively. For the PM10 metrics it was also possible to investigate the accordance between the model-based and the measurements-based dust-PM10. This comparison confirmed the PM10 model overestimation to be related to over-predicted dust mass by a factor of 140 %.

scholarly journals Aerosol events in the broader Mediterranean basin based on 7-year (2000–2007) MODIS C005 data

2009 ◽  
Vol 27 (9) ◽  
pp. 3509-3522 ◽  
Author(s):  
A. Gkikas ◽  
N. Hatzianastassiou ◽  
N. Mihalopoulos
Keyword(s):  
Forest Fires ◽  
Mediterranean Basin ◽  
Eastern Mediterranean ◽  
Spatiotemporal Variability ◽  
Central Mediterranean ◽  
Dust Transport ◽  
Spatial Coverage ◽  
Moderate Resolution ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Year 2000

Abstract. Aerosol events (their frequency and intensity) in the broader Mediterranean basin were studied using 7-year (2000–2007) aerosol data of optical depth (AOD at 550 nm) from the MODerate Resolution Imaging Spectroradiometer (MODIS) Terra. The complete spatial coverage of data revealed a significant spatial variability of aerosol events which is also dependent on their intensity. Strong events occur more often in the western and central Mediterranean basin (up to 14 events/year) whereas extreme events (AOD up to 5.0) are systematically observed in the eastern Mediterranean basin throughout the year. There is also a significant seasonal variability with strong aerosol events occurring most frequently in the western part of the basin in summer and extreme episodes in the eastern part during spring. The events were also analyzed separately over land and sea revealing differences that are due to the different natural and anthropogenic processes, like dust transport (producing maximum frequencies of extreme episodes in spring over both land and sea) or forest fires (producing maximum frequencies in strong episodes in summer over land). The inter-annual variability shows a gradual decrease in the frequency of all aerosol episodes over land and sea areas of the Mediterranean during the period 2000–2007, associated with an increase in their intensity (increased AOD values). The strong spatiotemporal variability of aerosol events indicates the need for monitoring them at the highest spatial and temporal coverage and resolution.

scholarly journals Evidence of a prolonged drought ca. 4200 yr BP correlated with prehistoric settlement abandonment from the Gueldaman GLD1 Cave, Northern Algeria

2016 ◽  
Vol 12 (1) ◽  
pp. 1-14 ◽  
Author(s):  
J. Ruan ◽  
F. Kherbouche ◽  
D. Genty ◽  
D. Blamart ◽  
H. Cheng ◽  
...  
Keyword(s):  
Mediterranean Basin ◽  
Eastern Mediterranean ◽  
Western Mediterranean ◽  
Faunal Remains ◽  
Carbon And Oxygen Isotopes ◽  
Northern Algeria ◽  
Western Mediterranean Basin ◽  
Prolonged Drought ◽  
Eastern Mediterranean Basin ◽  
The Mediterranean

Abstract. Middle Holocene cultures have been widely studied around the Eastern-Mediterranean basin in the last 30 years and past cultural activities have been commonly linked with regional climate changes. However, in many cases such linkage is equivocal, in part due to existing climatic evidence that has been derived from areas outside the distribution of ancient settlements, leading to uncertainty from complex spatial heterogeneity in both climate and demography. A few high-resolution well-dated paleoclimate records were recently established using speleothems in the Central and Eastern-Mediterranean basin, however, the scarcity of such records in the western part of the Mediterranean prevents us from correlating past climate evolutions across the basin and deciphering climate–culture relation at fine timescales. Here we report the first decadal-resolved Mid-Holocene climate proxy records from the Western-Mediterranean basin based on the stable carbon and oxygen isotopes analyses of two U/Th dated stalagmites from the Gueldaman GLD1 Cave in Northern Algeria. Comparison of our records with those from Italy and Israel reveals synchronous (multi) centennial dry phases centered at ca. 5600, ca. 5200 and ca. 4200 yr BP across the Mediterranean basin. New calibrated radiocarbon dating constrains reasonably well the age of rich anthropogenic deposits (e.g., faunal remains, pottery, charcoal) excavated inside the cave, which allows the comparison between in situ evidence of human occupation and of climate change. This approach shows that the timing of a prolonged drought at ca. 4400–3800 yr BP blankets the onset of cave abandonment shortly after ca. 4403 cal yr BP, supporting the hypothesis that a climate anomaly may have played a role in this cultural disruption.

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