scholarly journals Remote sensing of aerosols over the oceans using MSG/SEVIRI imagery

2005 ◽  
Vol 23 (12) ◽  
pp. 3561-3568 ◽  
Author(s):  
F. Thieuleux ◽  
C. Moulin ◽  
F. M. Bréon ◽  
F. Maignan ◽  
J. Poitou ◽  
...  
Keyword(s):  
Optical Thickness ◽  
Saharan Dust ◽  
Dust Transport ◽  
High Frequencies ◽  
Full Resolution ◽  
Fast Processing ◽  
Long Time ◽  
The Mediterranean ◽  
Good Agreement

Abstract. The SEVIRI instrument on board Meteosat Second Generation (MSG) offers new capabilities to monitor aerosol transport over the Atlantic and the Mediterranean at high temporal and spatial resolutions, in particular, Saharan dust from North Africa, biomass-burning aerosols from subtropical Africa and pollution from Europe. An inversion technique was developed to estimate both aerosol optical thickness and Angström coefficients from SEVIRI measurements at 0.63 and 0.81 µm. This method relies on an optimized set of aerosol models to ensure a fast processing of full-resolution MSG images and to allow the processing of long time series. SEVIRI images for slots 45, 49 and 53 (11:15, 12:15, 13:15 UT) were processed for June 2003. The retrieved optical thicknesses and Angström coefficients are in good agreement with AERONET in-situ measurements in the Atlantic and in the Mediterranean. Monthly mean maps of both parameters are compared to that obtained with the polar orbiting sensor POLDER for June 2003. There is a good consistency between the two monthly means in terms of optical thickness, but the Angström coefficients show significant differences in the Atlantic zone which is affected by dust transport. These differences may be explained by the lack of specific non-spherical dust models within the inversion. The preliminary results presented in this paper demonstrate, nevertheless, the potential of MSG/SEVIRI for the monitoring of aerosol optical properties at high frequencies over the Atlantic and the Mediterranean.

scholarly journals Three-dimensional evolution of Saharan dust transport towards Europe based on a 9-year EARLINET-optimized CALIPSO dataset

2017 ◽  
Vol 17 (9) ◽  
pp. 5893-5919 ◽  
Author(s):  
Eleni Marinou ◽  
Vassilis Amiridis ◽  
Ioannis Binietoglou ◽  
Athanasios Tsikerdekis ◽  
Stavros Solomos ◽  
...  
Keyword(s):  
Cloud Condensation Nuclei ◽  
Three Dimensional ◽  
Satellite Observation ◽  
Saharan Dust ◽  
Winter Period ◽  
Dust Transport ◽  
The Balkans ◽  
Potential Applications ◽  
The Mediterranean ◽  
Dust Evolution

Abstract. In this study we use a new dust product developed using CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) observations and EARLINET (European Aerosol Research Lidar Network) measurements and methods to provide a 3-D multiyear analysis on the evolution of Saharan dust over North Africa and Europe. The product uses a CALIPSO L2 backscatter product corrected with a depolarization-based method to separate pure dust in external aerosol mixtures and a Saharan dust lidar ratio (LR) based on long-term EARLINET measurements to calculate the dust extinction profiles. The methodology is applied on a 9-year CALIPSO dataset (2007–2015) and the results are analyzed here to reveal for the first time the 3-D dust evolution and the seasonal patterns of dust over its transportation paths from the Sahara towards the Mediterranean and Continental Europe. During spring, the spatial distribution of dust shows a uniform pattern over the Sahara desert. The dust transport over the Mediterranean Sea results in mean dust optical depth (DOD) values up to 0.1. During summer, the dust activity is mostly shifted to the western part of the desert where mean DOD near the source is up to 0.6. Elevated dust plumes with mean extinction values between 10 and 75 Mm−1 are observed throughout the year at various heights between 2 and 6 km, extending up to latitudes of 40° N. Dust advection is identified even at latitudes of about 60° N, but this is due to rare events of episodic nature. Dust plumes of high DOD are also observed above the Balkans during the winter period and above northwest Europe during autumn at heights between 2 and 4 km, reaching mean extinction values up to 50 Mm−1. The dataset is considered unique with respect to its potential applications, including the evaluation of dust transport models and the estimation of cloud condensation nuclei (CCN) and ice nuclei (IN) concentration profiles. Finally, the product can be used to study dust dynamics during transportation, since it is capable of revealing even fine dynamical features such as the particle uplifting and deposition on European mountainous ridges such as the Alps and Carpathian Mountains.

scholarly journals Synergetic monitoring of Saharan dust plumes and potential impact on surface: a case study of dust transport from Canary Islands to Iberian Peninsula

2011 ◽  
Vol 11 (7) ◽  
pp. 3067-3091 ◽  
Author(s):  
C. Córdoba-Jabonero ◽  
M. Sorribas ◽  
J. L. Guerrero-Rascado ◽  
J. A. Adame ◽  
Y. Hernández ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Particle Deposition ◽  
Ground Level ◽  
In Situ Measurements ◽  
Saharan Dust ◽  
Dust Transport ◽  
Air Masses ◽  
Potential Impact

Abstract. The synergetic use of meteorological information, remote sensing both ground-based active (lidar) and passive (sun-photometry) techniques together with backtrajectory analysis and in-situ measurements is devoted to the characterization of dust intrusions. A case study of air masses advected from the Saharan region to the Canary Islands and the Iberian Peninsula, located relatively close and far away from the dust sources, respectively, was considered for this purpose. The observations were performed over three Spanish geographically strategic stations within the dust-influenced area along a common dust plume pathway monitored from 11 to 19 of March 2008. A 4-day long dust event (13–16 March) over the Santa Cruz de Tenerife Observatory (SCO), and a linked short 1-day dust episode (14 March) in the Southern Iberian Peninsula over the Atmospheric Sounding Station "El Arenosillo" (ARN) and the Granada station (GRA) were detected. Meteorological conditions favoured the dust plume transport over the area under study. Backtrajectory analysis clearly revealed the Saharan region as the source of the dust intrusion. Under the Saharan air masses influence, AERONET Aerosol Optical Depth at 500 nm (AOD500) ranged from 0.3 to 0.6 and Ångström Exponent at 440/675 nm wavelength pair (AE440/675) was lower than 0.5, indicating a high loading and predominance of coarse particles during those dusty events. Lidar observations characterized their vertical layering structure, identifying different aerosol contributions depending on altitude. In particular, the 3-km height dust layer transported from the Saharan region and observed over SCO site was later on detected at ARN and GRA stations. No significant differences were found in the lidar (extinction-to-backscatter) ratio (LR) estimation for that dust plume over all stations when a suitable aerosol scenario for lidar data retrieval is selected. Lidar-retrieved LR values of 60–70 sr were obtained during the main dust episodes. These similar LR values found in all the stations suggest that dust properties were kept nearly unchanged in the course of its medium-range transport. In addition, the potential impact on surface of that Saharan dust intrusion over the Iberian Peninsula was evaluated by means of ground-level in-situ measurements for particle deposition assessment together with backtrajectory analysis. However, no connection between those dust plumes and the particle sedimentation registered at ground level is found. Differences on particle deposition processes observed in both Southern Iberian Peninsula sites are due to the particular dust transport pattern occurred over each station. Discrepancies between columnar-integrated and ground-level in-situ measurements show a clear dependence on height of the dust particle size distribution. Then, further vertical size-resolved observations are needed for evaluation of the impact on surface of the Saharan dust arrival to the Iberian Peninsula.

scholarly journals MODELING THE TRANS-ATLANTIC TRANSPORTATION OF SAHARAN DUST

2017 ◽  
Vol 50 (2) ◽  
pp. 1052
Author(s):  
A. Tsikerdekis ◽  
P. Zanis ◽  
L.A. Steiner ◽  
V. Amiridis ◽  
E. Marinou ◽  
...  
Keyword(s):  
Optical Thickness ◽  
Climate Model ◽  
Regional Climate ◽  
Saharan Dust ◽  
Dust Transport ◽  
South Central ◽  
Vertical Distributions ◽  
Dust Loading ◽  
Horizontal And Vertical Distributions ◽  
The Vertical Distribution

In the present study we are simulating the trans-Atlantic transport of dust from Sahara to the South-Central America, using the regional climate model RegCM4 and its online dust scheme, for the year 2007. The simulated horizontal and vertical distributions of the mineral dust optical properties were evaluated against the LIVAS CALIPSO satellite dust product. The Trans-Atlantic dust transport is simulated adequately with RegCM4, but there are some spatial discrepancies. Dust optical thickness is overestimated in the eastern Sahara throughout the year by 0.1-0.2, while near the gulf of Guinea is underestimated during winter and spring. Although RegCM4 dust plume is located southern on winter and spring, it doesn't spatially match the dust optical thickness of LIVAS. In summer and autumn the vertical distribution of dust between 3-4km during the Trans-Atlantic transport is simulated by the model adequately up to 30ºW 40ºW longitude. However, during winter-spring RegCM4 misplaces dust loading into higher altitude. Finally, we discuss some possible reasons and mechanisms that might be responsible for the differences between the model and the observations. 

scholarly journals Mediterranean Sea climatic indices: monitoring long-term variability and climate changes

2018 ◽  
Vol 10 (4) ◽  
pp. 1829-1842 ◽  
Author(s):  
Athanasia Iona ◽  
Athanasios Theodorou ◽  
Sarantis Sofianos ◽  
Sylvain Watelet ◽  
Charles Troupin ◽  
...  
Keyword(s):  
Time Series ◽  
Mediterranean Sea ◽  
Climate Changes ◽  
Salt Content ◽  
Climatic Indices ◽  
Long Time ◽  
In Situ Observations ◽  
The Mediterranean

Abstract. We present a new product composed of a set of thermohaline climatic indices from 1950 to 2015 for the Mediterranean Sea such as decadal temperature and salinity anomalies, their mean values over selected depths, decadal ocean heat and salt content anomalies at selected depth layers as well as their long time series. It is produced from a new high-resolution climatology of temperature and salinity on a 1∕8∘ regular grid based on historical high-quality in situ observations. Ocean heat and salt content differences between 1980–2015 and 1950–1979 are compared for evaluation of the climate shift in the Mediterranean Sea. The two successive periods are chosen according to the standard WMO climate normals. The spatial patterns of heat and salt content shifts demonstrate that the climate changes differently in the several regions of the basin. Long time series of heat and salt content for the period 1950 to 2015 are also provided which indicate that in the Mediterranean Sea there is a net mean volume warming and salinification since 1950 that has accelerated during the last two decades. The time series also show that the ocean heat content seems to fluctuate on a cycle of about 40 years and seems to follow the Atlantic Multidecadal Oscillation climate cycle, indicating that the natural large-scale atmospheric variability could be superimposed onto the warming trend. This product is an observation-based estimation of the Mediterranean climatic indices. It relies solely on spatially interpolated data produced from in situ observations averaged over decades in order to smooth the decadal variability and reveal the long-term trends. It can provide a valuable contribution to the modellers' community, next to the satellite-based products, and serve as a baseline for the evaluation of climate-change model simulations, thus contributing to a better understanding of the complex response of the Mediterranean Sea to the ongoing global climate change. The product is available in netCDF at the following sources: annual and seasonal T∕S anomalies (https://doi.org/10.5281/zenodo.1408832), annual and seasonal T∕S vertical averaged anomalies (https://doi.org/10.5281/zenodo.1408929), annual and seasonal areal density of OHC/OSC anomalies (https://doi.org/10.5281/zenodo.1408877), annual and seasonal linear trends of T∕S, OHC/OSC anomalies (https://doi.org/10.5281/zenodo.1408917), annual and seasonal time series of T∕S, OHC/OSC anomalies (https://doi.org/10.5281/zenodo.1411398), and differences of two 30-year averages of annual and seasonal T∕S, OHC/OSC anomalies (https://doi.org/10.5281/zenodo.1408903).

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 3D evolution of Saharan dust transport towards Europe based on a 9-year EARLINET-optimized CALIPSO dataset

2016 ◽  
Author(s):  
Eleni Marinou ◽  
Vassilis Amiridis ◽  
Ioannis Binietoglou ◽  
Stavros Solomos ◽  
Emannouil Proestakis ◽  
...  
Keyword(s):  
Saharan Dust ◽  
Winter Period ◽  
Dust Transport ◽  
North West ◽  
Ice Nuclei ◽  
Potential Applications ◽  
Lidar Ratio ◽  
The Mediterranean ◽  
Dust Evolution ◽  
First Time

Abstract. In this study we utilize a new dust product developed using CALIPSO observations and EARLINET measurements and methods to provide a 3D multiyear analysis on the evolution of Saharan dust over North Africa and Europe. The product utilizes CALIPSO L2 backscatter product corrected with a depolarization-based method to separate pure dust in external aerosol mixtures and an adjusted Saharan dust lidar ratio based on long-term EARLINET measurements. The methodology is applied on a nine-year CALIPSO dataset (2007–2015) and the results are analysed here to reveal for the first time the 3D dust evolution and the seasonal patterns of dust over its transportation paths from the Sahara towards the Mediterranean and Continental Europe. During spring, dust is uniformly distributed in the horizontal over the Sahara desert. The dust transport over the Mediterranean Sea results on mean Dust Optical Depth (DOD) values of 0.1. During summer, the dust activity is mostly shifted to the western part of the desert where mean DOD near the source is up to 0.6. Elevated dust plumes with mean extinction values between 10–75 Mm−1 are observed throughout the year at various heights between 2–6 km, extending up to latitudes of 40° N. Dust advection is identified even at latitudes of about 60° N, but this is due to rare events of episodic nature. Dust plumes of high DOD are also observed above Balkans during winter period and above North-West Europe during autumn at heights between 2–4 km, reaching mean extinction values up to 50 Mm−1. The dataset is considered unique with respect to its potential applications, including the evaluation of dust transport models and the estimation of cloud condensation and ice nuclei concentration profiles (CCN/IN). Finally, the product can be used to study dust dynamics during transportation, since it is capable of revealing even fine dynamical features such as the particle uplifting and deposition on European mountainous ridges such as Alps and Carpathian.

scholarly journals Modelling Saharan dust transport into the Mediterranean basin with CMAQ

2013 ◽  
Vol 70 ◽  
pp. 337-350 ◽  
Author(s):  
David de la Paz ◽  
Michel Vedrenne ◽  
Rafael Borge ◽  
Julio Lumbreras ◽  
Juan Manuel de Andrés ◽  
...  
Keyword(s):  
Mediterranean Basin ◽  
Saharan Dust ◽  
Dust Transport ◽  
The Mediterranean ◽  
The Mediterranean Basin
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