scholarly journals Investigation of an Intense Dust Outbreak in the Mediterranean Using XMed-Dry Network, Multiplatform Observations, and Numerical Modeling

2021 ◽  
Vol 11 (4) ◽  
pp. 1566
Author(s):  
Umberto Rizza ◽  
Konrad Kandler ◽  
Melanie Eknayan ◽  
Giorgio Passerini ◽  
Enrico Mancinelli ◽  
...  
Keyword(s):  
Particle Size ◽  
Dust Emission ◽  
Wrf Model ◽  
Saharan Dust ◽  
Aerosol Model ◽  
Need To Evaluate ◽  
Aerosol Particle Size ◽  
Southern Mediterranean ◽  
The Mediterranean ◽  
Size Limits

The Weather Research and Forecasting (WRF) model with online coupled chemistry (WRF-Chem) is applied to study an intense Saharan dust outbreak event affecting the Italian peninsula in 15 and 16 April 2018. According to the MODIS retrievals, this intrusion was characterized by an intense aerosol optical depth (AOD) peak value in the southern Mediterranean. Measurements within the Dry Deposition Network Across the Mediterranean (XMed-Dry) are compared with the output of the WRF-Chem model. XMed-Dry samples from Lecce (Italy), Athens (Greece) and San Lawrenz/Gozo (Malta) were analysed with respect to aerosol particle size distribution, relative dust contribution, and composition. The discrepancy between the model and measured deposition indicate the need to formulate in WRF-Chem more sophisticated deposition schemes, this will need to evaluate the sensitivity of the results to the precise particle size limits chosen for the aerosol model. Moreover, satellite retrievals from MODIS sensors elaborated with the MAIAC algorithm, Aeronet stations, and measurements of PM10 at the selected sites were also considered. In a numerical domain that spans the Mediterranean and the northern Saharan desert, two different dust emission schemes, namely Gocart-AFWA and the Shao-2001, were tested and compared with multiplatform observations for simulation period covering the dust outbreak. Actual results indicate that both emission schemes would benefit from replacing the static erodibility map and soil particle distribution with remote sensed and in-situ observational data.

scholarly journals WRF-CHEM SIMULATION OF A SAHARAN DUST OUTBREAK OVER THE MEDITERRANEAN REGIONS

2016 ◽  
Vol 38 ◽  
pp. 330 ◽  
Author(s):  
Umberto Rizza ◽  
Vagner Anabor ◽  
Cristina Mangia ◽  
Mario Marcello Miglietta ◽  
Gervasio Annes Degrazia ◽  
...  
Keyword(s):  
Dust Emission ◽  
Saharan Dust ◽  
Dust Event ◽  
Aerosol Model ◽  
Tuning Parameters ◽  
Mediterranean Regions ◽  
Time Average ◽  
The Mediterranean ◽  
Fully Coupled

A fully coupled meteorology-chemistry-aerosol model (WRF-Chem) is applied to simulate the Saharan dust outbreak over the Mediterranean regions. Two dust emission schemes, namely, those of Jones et al., (2010), and Shao (2001) are evaluated using the the GOCART aerosol model. To investigate the performance of each dust emission scheme, a case study was carried out for a Mediterranean dust event that took place between 21 and 23 May 2014. Considering the time average Aerosol Optical Depth, simulation results reproduced satisfactorily the outbreak and transport pattern of dust plumes. However, the estimated dust emission amounts in each scheme differ greatly due to the presence of several tuning parameters, that must be adjusted considering satellite and ground based experimental data.

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 %.

Airborne measurements of dust layer properties, particle size distribution and mixing state of Saharan dust during SAMUM 2006

Tellus B ◽  
2009 ◽  
Vol 61 (1) ◽  
Author(s):  
Bernadett Weinzierl ◽  
Andreas Petzold ◽  
Michael Esselborn ◽  
Martin Wirth ◽  
Katharina Rasp ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Saharan Dust ◽  
Mixing State ◽  
Dust Layer ◽  
Airborne Measurements

scholarly journals The Potential of GRASP/GARRLiC Retrievals for Dust Aerosol Model Evaluation: Case Study during the PreTECT Campaign

2021 ◽  
Vol 13 (5) ◽  
pp. 873
Author(s):  
Dimitra Konsta ◽  
Alexandra Tsekeri ◽  
Stavros Solomos ◽  
Nikolaos Siomos ◽  
Anna Gialitaki ◽  
...  
Keyword(s):  
Model Evaluation ◽  
Dust Concentration ◽  
Saharan Dust ◽  
North Coast ◽  
Concentration Profiles ◽  
Future Studies ◽  
Aerosol Model ◽  
The North ◽  
Sun Photometer

We use the Generalized Retrieval of Aerosol Surface Properties algorithm (GRASP) to compare with dust concentration profiles derived from the NMME-DREAM model for a specific dust episode. The GRASP algorithm provides the possibility of deriving columnar and vertically-resolved aerosol properties from a combination of lidar and sun-photometer observations. Herein, we apply GRASP for analysis of a Saharan dust outburst observed during the “PREparatory: does dust TriboElectrification affect our ClimaTe” campaign (PreTECT) that took place at the North coast of Crete, at the Finokalia ACTRIS station. GRASP provides column-averaged and vertically resolved microphysical and optical properties of the particles. The retrieved dust concentration profiles are compared with modeled concentration profiles derived from the NMME-DREAM dust model. To strengthen the results, we use dust concentration profiles from the POlarization-LIdar PHOtometer Networking method (POLIPHON). A strong underestimation of the maximum dust concentration is observed from the NMME-DREAM model. The reported differences between the retrievals and the model indicate a high potential of the GRASP algorithm for future studies of dust model evaluation.

scholarly journals The two-sided spectacle at the border: Frontex, NGOs and the theatres of sovereignty

2021 ◽  
pp. 136248062110078
Author(s):  
Katja Franko
Keyword(s):  
Visual Analysis ◽  
Ethical Dilemmas ◽  
Moral Authority ◽  
Living Conditions ◽  
Coast Guard ◽  
The Past ◽  
Southern Mediterranean ◽  
The Mediterranean ◽  
A Site ◽  
Previous Scholarship

The Southern Mediterranean border has in the past decade become one of the most deeply contested political spaces in Europe and has been described as a site of the border spectacle. Drawing on textual and visual analysis of Twitter messages by two of the most prominent actors in the field, the European Border and Coast Guard Agency, Frontex, and the humanitarian and medical NGO Médecins Sans Frontières, the article examines the split nature of the Mediterranean border which is, among others, visible in radically different narratives about migrants’ journeys, border deaths and living conditions. The findings challenge previous scholarship about convergence of humanitarianism and policing. The two actors are waging a fierce media battle for moral authority, where they use widely diverging strategies of claiming authority, each of which carries a particular set of ethical dilemmas.

scholarly journals New developments in the representation of Saharan dust sources in the aerosol–climate model ECHAM6-HAM2

2016 ◽  
Vol 9 (2) ◽  
pp. 765-777 ◽  
Author(s):  
Bernd Heinold ◽  
Ina Tegen ◽  
Kerstin Schepanski ◽  
Jamie R. Banks
Keyword(s):  
Climate Model ◽  
Dust Emission ◽  
Source Area ◽  
Saharan Dust ◽  
Moist Convection ◽  
Dust Source ◽  
New Developments ◽  
Infrared Imager ◽  
Dust Sources ◽  
Dust Events

Abstract. In the aerosol–climate model ECHAM6-HAM2, dust source activation (DSA) observations from Meteosat Second Generation (MSG) satellite are proposed to replace the original source area parameterization over the Sahara Desert. The new setup is tested in nudged simulations for the period 2007 to 2008. The evaluation is based on comparisons to dust emission events inferred from MSG dust index imagery, Aerosol Robotic Network (AERONET) sun photometer observations, and satellite retrievals of aerosol optical thickness (AOT).The model results agree well with AERONET measurements especially in terms of seasonal variability, and a good spatial correlation was found between model results and MSG-SEVIRI (Spinning-Enhanced Visible and InfraRed Imager) dust AOT as well as Multi-angle Imaging SpectroRadiometer (MISR) AOT. ECHAM6-HAM2 computes a more realistic geographical distribution and up to 20 % higher annual Saharan dust emissions, using the MSG-based source map. The representation of dust AOT is partly improved in the southern Sahara and Sahel. In addition, the spatial variability is increased towards a better agreement with observations depending on the season. Thus, using the MSG DSA map can help to circumvent the issue of uncertain soil input parameters.An important issue remains the need to improve the model representation of moist convection and stable nighttime conditions. Compared to sub-daily DSA information from MSG-SEVIRI and results from a regional model, ECHAM6-HAM2 notably underestimates the important fraction of morning dust events by the breakdown of the nocturnal low-level jet, while a major contribution is from afternoon-to-evening emissions.

Influence of Saharan dust on the rain acidity and atmospheric input to the Mediterranean

Nature ◽  
1986 ◽  
Vol 321 (6068) ◽  
pp. 427-428 ◽  
Author(s):  
M. D. Loÿe-Pilot ◽  
J. M. Martin ◽  
J. Morelli
Keyword(s):  
Saharan Dust ◽  
Atmospheric Input ◽  
The Mediterranean

scholarly journals Longitudinal variability of the biogeochemical role of Mediterranean aerosols in the Mediterranean Sea

2011 ◽  
Vol 8 (5) ◽  
pp. 1067-1080 ◽  
Author(s):  
E. Ternon ◽  
C. Guieu ◽  
C. Ridame ◽  
S. L'Helguen ◽  
P. Catala
Keyword(s):  
Mediterranean Sea ◽  
Forest Fires ◽  
Saharan Dust ◽  
Aerosol Sampling ◽  
Modest Contribution ◽  
Anthropogenic Contribution ◽  
The Mediterranean ◽  
June July ◽  
Atmospheric Inputs ◽  
Longitudinal Variability

Abstract. The Mediterranean Sea is a semi-enclosed basin characterized by a strong thermal stratification during summer during which the atmosphere is the main source of new nutrients to the nutrient-depleted surface layer. From aerosol sampling and microcosm experiments performed during the TransMed BOUM cruise (June–July 2008) we showed that: (i) the Mediterranean atmosphere composition (Al, Fe, P) was homogeneous over ~28° of longitude and was a mixture with a constant proportion of anthropogenic contribution and a variable but modest contribution of crustal aerosols. This quite stable composition over a one month period and a long transect (~2500 km) allowed to define the Mediterranean atmospheric "background" that characterizes the summer season in the absence of major Saharan event and forest fires, (ii) primary production significantly increased at all tested stations after aerosols addition collected on-board and after Saharan dust analog addition, indicating that both additions relieved on-going (co)-limitations. Although both additions significantly increased the N2 fixation rates at the western station, diazotrophic activity remained very low (~0.2 nmol N L−1 d−1), (iii) due to the presence of anthropogenic particles, the probable higher solubility of nutrients associated with mixed aerosols (crustal + anthropogenic contribution), conferred a higher fertilizing potential to on-board collected aerosol as compared to Saharan dust analog. Finally, those experiments showed that atmospheric inputs from a mixed atmospheric event ("summer rain" type) or from a high-intensity Saharan event would induce comparable response by the biota in the stratified Mediterranean SML, during summer.

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