scholarly journals Measurements of Saharan dust aerosols over the Eastern Mediterranean using elastic backscatter-Raman lidar, spectrophotometric and satellite observations in the frame of the EARLINET project

2005 ◽  
Vol 5 (8) ◽  
pp. 2065-2079 ◽  
Author(s):  
A. Papayannis ◽  
D. Balis ◽  
V. Amiridis ◽  
G. Chourdakis ◽  
G. Tsaknakis ◽  
...  
Keyword(s):  
Eastern Mediterranean ◽  
Mean Value ◽  
Saharan Dust ◽  
Back Trajectory ◽  
Air Mass ◽  
Mean Values ◽  
Dust Aerosols ◽  
Back Trajectory Analysis ◽  
Spectrophotometric Data ◽  
Lidar Ratio

Abstract. We report on the vertical distributions of Saharan dust aerosols over the N.E. Mediterranean region, which were obtained during a typical dust outbreak on August 2000, by two lidar systems located in Athens and Thessaloniki, Greece, in the frame of the European EARLINET project. MODIS and ground sun spectrophotometric data, as well as air-mass backward trajectories confirmed the existence of Saharan dust in the case examined, which was also successfully forecasted by the DREAM dust model. The lidar data analysis for the period 2000-2002 made possible, for the first time, an estimation of the vertical extent of free tropospheric dust layers [mean values of the aerosol backscatter and extinction coefficients and the extinction-to-backscatter ratio (lidar ratio, LR) at 355 nm], as well as a seasonal distribution of Saharan dust outbreaks over Greece, under cloud-free conditions. A mean value of the lidar ratio at 355 nm was obtained over Athens (53±1 sr) and over Thessaloniki (44±2 sr) during the Saharan dust outbreaks. The corresponding aerosol optical thickness (AOT) at 355 nm, in the altitude range 0-5 km, was 0.69±0.12 and 0.65±0.10 for Athens and Thessaloniki, respectively (within the dust layer the AOT was 0.23 and 0.21, respectively). Air-mass back-trajectory analysis performed in the period 2000-2002 for all Saharan dust outbreaks over the N.E. Mediterranean indicated the main pathways followed by the dust aerosols.

scholarly journals Measurements of Saharan dust aerosols over the Eastern Mediterranean using elastic backscatter-Raman lidar, spectrophotometric and satellite observations in the frame of the EARLINET project

2005 ◽  
Vol 5 (2) ◽  
pp. 2075-2110 ◽  
Author(s):  
A. Papayannis ◽  
D. Balis ◽  
V. Amiridis ◽  
G. Chourdakis ◽  
G. Tsaknakis ◽  
...  
Keyword(s):  
Eastern Mediterranean ◽  
Mean Value ◽  
Saharan Dust ◽  
Back Trajectory ◽  
Air Mass ◽  
Mean Values ◽  
Dust Aerosols ◽  
Back Trajectory Analysis ◽  
Spectrophotometric Data ◽  
Lidar Ratio

Abstract. We report on the vertical distributions of Saharan dust aerosols over the N.E. Mediterranean region, which were obtained during a typical dust outbreak on August 2000, by two lidar systems located in Athens and Thessaloniki, Greece, in the frame of the European EARLINET project. MODIS and ground sun spectrophotometric data, as well as air-mass backward trajectories confirmed the existence of Saharan dust in the case examined, which was also successfully forecasted by the DREAM dust model. The lidar data analysis for the period 2000–2002 made possible, for the first time, an estimation of the vertical extent of free tropospheric dust layers (mean values of the aerosol backscatter and extinction coefficients and the extinction-to-backscatter ratio (lidar ratio, LR) at 355 nm), as well as a seasonal distribution of Saharan dust outbreaks over Greece, under cloud-free conditions. A mean value of the lidar ratio at 355 nm was obtained over Athens (52.81±1.02 sr) and over Thessaloniki (44.19±1.72 sr) during the Saharan dust outbreaks. The corresponding aerosol optical thickness (AOT) at 355 nm, in the altitude range 0–5 km, was 0.69±0.12 and 0.65±0.10 for Athens and Thessaloniki, respectively (within the dust layer the AOT was 0.23 and 0.21, respectively). Air-mass back-trajectory analysis performed in the period 2000–2002 for all Saharan dust outbreaks over the N. E. Mediterranean indicated the main pathways followed by the dust aerosols.

scholarly journals Seventeen-year systematic measurements of dust aerosol optical properties using the eole ntua lidar system (2000-2016)

2018 ◽  
Vol 176 ◽  
pp. 05029
Author(s):  
Ourania Soupiona ◽  
Maria Mylonaki ◽  
Alexandros Papayannis ◽  
Athina Argyrouli ◽  
Panayotis Kokkalis ◽  
...  
Keyword(s):  
Optical Properties ◽  
Mean Value ◽  
Saharan Dust ◽  
Aerosol Optical Properties ◽  
Mean Values ◽  
Time Period ◽  
Lidar Measurements ◽  
Multi Wavelength ◽  
Lidar Ratio ◽  
Dust Events

A comprehensive analysis of the seasonal variability of the optical properties of Saharan dust aerosols over Athens, Greece, is presented for a 17-year time period (2000-2016), as derived from multi-wavelength Raman lidar measurements (57 dust events with more than 80 hours of measurements). The profiles of the derived aerosol optical properties (aerosol backscatter and extinction coefficients, lidar ratio and aerosol Ångström exponent) at 355 nm are presented. For these dust events we found a mean value of the lidar ratio of ~52±13 sr at 355 nm and of ~58±8 sr (not shown) at 532 nm (2-4 km a.s.l. height). For our statistical analysis, presented here, we used monthly-mean values and time periods under cloud-free conditions. The number of dust events was greatest in late spring, summer, and early autumn periods. In this paper we also present a selected case study (04 April 2016) of desert dust long-range transport from the Saharan desert.

scholarly journals Lidar Ratio Derived for Pure Dust Aerosols: Multi-Year Micro Pulse Lidar Observations in a Saharan Dust-Influenced Region

2016 ◽  
Vol 119 ◽  
pp. 23017 ◽  
Author(s):  
Carmen Córdoba-Jabonero ◽  
José Antonio Adame ◽  
James R. Campbell ◽  
Emilio Cuevas ◽  
Juan Pedro Díaz ◽  
...  
Keyword(s):  
Saharan Dust ◽  
Dust Aerosols ◽  
Lidar Ratio ◽  
Micro Pulse Lidar ◽  
Lidar Observations

scholarly journals Lidar Measuremnt on Dust Transport from the Saharan Desert to the Iran Plateau

2020 ◽  
Vol 237 ◽  
pp. 02020
Author(s):  
Hossein Panahifar ◽  
Ruhollah Moradhaseli ◽  
Hadi Bourzoie ◽  
Mahdi Gholami ◽  
Hamid Reza Khalesifard
Keyword(s):  
Trajectory Analysis ◽  
Saharan Dust ◽  
Dust Particles ◽  
Raman Lidar ◽  
Dust Layer ◽  
Mean Values ◽  
Dust Transport ◽  
Lidar Ratio ◽  
532 Nm ◽  
Iran Plateau

Optical properties of long-range Saharan dust particles transported to the Iran Plateau have been investigated. The results were derived from the measurements of a dual-wavelength Depolarized backscatter/Raman lidar and a Cimel CE318-2 sunphotometer. Observations were performed in Zanjan, Northwest Iran. The backward trajectory analysis show that the lofted dust plumes come from the Saharan desert and travel along Mediterranean Sea and Turkey toward Iran. The lidar ratio within the lofted dust layer has been found with mean values of 50 sr at 532 nm. For the depolarization ratio, mean values of 25% have been found.

Air mass origins by back trajectory analysis for evaluating atmospheric 210Pb concentrations at Rokkasho, Aomori, Japan

2009 ◽  
Vol 279 (2) ◽  
pp. 493-498 ◽  
Author(s):  
N. Akata ◽  
H. Kawabata ◽  
H. Hasegawa ◽  
K. Kondo ◽  
T. Sato ◽  
...  
Keyword(s):  
Trajectory Analysis ◽  
Back Trajectory ◽  
Air Mass ◽  
Back Trajectory Analysis

scholarly journals MAX-DOAS retrieval of aerosol extinction properties in Madrid, Spain

2016 ◽  
Author(s):  
Shanshan Wang ◽  
Carlos A. Cuevas ◽  
Udo Frieß ◽  
Alfonso Saiz-Lopez
Keyword(s):  
Saharan Dust ◽  
Optical Absorption Spectroscopy ◽  
Retrieval Algorithm ◽  
Back Trajectory ◽  
Aerosol Extinction ◽  
Inversion Algorithm ◽  
Back Trajectory Analysis ◽  
Particle Layer ◽  
Level Of Agreement

Abstract. Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements were performed in the urban environment of Madrid, Spain, from March to September in 2015. The O4 absorption in the UV was used to retrieve the aerosol extinction profile by an inversion algorithm. The results show a good agreement between the hourly retrieved aerosol optical depth (AOD) and the correlative Aerosol Robotic Network (AERONET) product, with a correlation coefficient of R = 0.87. Higher AODs are found in the summer season due to the more frequent occurrence of Saharan dust intrusions. The surface aerosol extinction coefficient as retrieved by the MAX-DOAS measurements was also compared to in situ PM2.5 concentrations. The level of agreement between both measurements indicates that the MAX-DOAS retrieval has the ability to characterize the extinction by particle near the surface. The retrieval algorithm was also used to study a case of severe dust intrusion on 12 May 2015. The capability of the MAX-DOAS retrieval to recognize the dust event including an elevated particle layer is investigated along with air mass back trajectory analysis.

scholarly journals Year-round record of near-surface ozone and O<sub>3</sub> enhancement events (OEEs) at Dome A, East Antarctica

2020 ◽  
Author(s):  
Minghu Ding ◽  
Biao Tian ◽  
Michael Ashley ◽  
Zhenxi Zhu ◽  
Lifan Wang ◽  
...  
Keyword(s):  
Surface Ozone ◽  
Dominant Factor ◽  
Back Trajectory ◽  
Dome A ◽  
Polar Night ◽  
Near Surface ◽  
Mean Values ◽  
Back Trajectory Analysis ◽  
Stratospheric Intrusion ◽  
Surface O3

Abstract. To evaluate the characteristics of near-surface O3 over Dome A (Kunlun Station), which is located at the summit of the east Antarctic Ice Sheet, continuous observations were carried out in 2016. Together with observations from the Amundsen–Scott Station (South Pole) and Zhongshan Station, the seasonal and diurnal O3 variabilities were investigated. The results showed different patterns between coastal and inland Antarctic areas that were characterized by high concentrations in cold seasons and at night. The annual mean values at the three stations were 29.19 ± 7.52 ppb, 29.94 ± 4.97 ppb and 24.06 ± 5.79 ppb. Then, specific atmospheric processes, including synoptic-scale air mass transport, were analysed by Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) back-trajectory analysis and the potential source contribution function (PSCF) model. Long-range transport was found to account for the O3 enhancement events (OEEs) during summer at Dome A, rather than efficient local production (consistent with previous studies in inland Antarctica). In addition, we observed OEEs during the polar night in the Dome A region, which was not previously found in Antarctica. To explain this unique finding, the occurrence of stratospheric intrusion (stratosphere-to-troposphere, STT) events was studied with the Stratosphere-to-Troposphere Exchange Flux (STEFLUX) tool. This finding suggested that STT events occurred frequently over Dome A and could account for 55 % of the total polar night period. The occurrence probability of OEEs agreed well with STT events, indicating that the STT process was the dominant factor affecting the near-surface O3 over Dome A in the absence of photochemical reaction sources during polar night. This work provides unique information on ozone variation at Dome A and expands our knowledge regarding such events in Antarctica.

scholarly journals MAX-DOAS retrieval of aerosol extinction properties in Madrid, Spain

2016 ◽  
Vol 9 (10) ◽  
pp. 5089-5101 ◽  
Author(s):  
Shanshan Wang ◽  
Carlos A. Cuevas ◽  
Udo Frieß ◽  
Alfonso Saiz-Lopez
Keyword(s):  
Saharan Dust ◽  
Optical Absorption Spectroscopy ◽  
Retrieval Algorithm ◽  
Back Trajectory ◽  
Aerosol Extinction ◽  
Inversion Algorithm ◽  
Back Trajectory Analysis ◽  
Particle Layer ◽  
Level Of Agreement

Abstract. Multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements were performed in the urban environment of Madrid, Spain, from March to September 2015. The O4 absorption in the ultraviolet (UV) spectral region was used to retrieve the aerosol extinction profile using an inversion algorithm. The results show a good agreement between the hourly retrieved aerosol optical depth (AOD) and the correlative Aerosol Robotic Network (AERONET) product, with a correlation coefficient of R =  0.87. Higher AODs are found in the summer season due to the more frequent occurrence of Saharan dust intrusions. The surface aerosol extinction coefficient as retrieved by the MAX-DOAS measurements was also compared to in situ PM2.5 concentrations. The level of agreement between both measurements indicates that the MAX-DOAS retrieval has the ability to characterize the extinction of aerosol particles near the surface. The retrieval algorithm was also used to study a case of severe dust intrusion on 12 May 2015. The capability of the MAX-DOAS retrieval to recognize the dust event including an elevated particle layer is investigated along with air mass back-trajectory analysis.

scholarly journals The Properties and Formation of Cirrus Clouds over the Tibetan Plateau Based on Summertime Lidar Measurements

2013 ◽  
Vol 70 (3) ◽  
pp. 901-915 ◽  
Author(s):  
Q. S. He ◽  
C. C. Li ◽  
J. Z. Ma ◽  
H. Q. Wang ◽  
G. M. Shi ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Large Scale ◽  
Longwave Radiation ◽  
Mean Value ◽  
Cirrus Clouds ◽  
The Tibetan Plateau ◽  
Mean Values ◽  
Upper Troposphere ◽  
Lidar Ratio ◽  
Highly Correlated

Abstract As part of the Tibet Ozone, Aerosol and Radiation (TOAR) project, a micropulse lidar was operated in Naqu (31.5°N, 92.1°E; 4508 m MSL) on the Tibetan Plateau to observe cirrus clouds continuously from 19 July to 26 August 2011. During the experiment, the time coverage of ice clouds only was 15% in the upper troposphere (above 9.5 km MSL). The cirrus top/bottom altitudes (mean values of 15.6/14.7 km) are comparable to those measured previously at tropical sites but relatively higher than those measured at midlatitude sites. The majority of the cloud layers yielded a lidar ratio between 10 and 40 sr, with a mean value of 28 ± 15 sr, characterized by a bimodal frequency distribution. Subvisible, thin, and opaque cirrus formation was observed in 16%, 34%, and 50% of all cirrus cases, respectively. A mean cirrus optical depth of 0.33 was observed over the Tibetan Plateau, slightly higher than those in the subtropics and tropics. With decreasing temperature, the lidar ratio increased slightly, whereas the mean extinction coefficient decreased significantly. The occurrence of clouds is highly correlated with the outgoing longwave radiation and the strong cold perturbations in the upper troposphere. Deep convective activity and Rossby waves are important dynamical processes that control cirrus variations over the Tibetan Plateau, where both anvil cirrus outflowing from convective cumulonimbus clouds and large-scale strong cold perturbations in the upper troposphere should play an important role in cirrus formation.

scholarly journals Ergosterol, arabitol and mannitol as tracers for biogenic aerosols in the eastern Mediterranean

2011 ◽  
Vol 11 (2) ◽  
pp. 829-839 ◽  
Author(s):  
N. Burshtein ◽  
N. Lang-Yona ◽  
Y. Rudich
Keyword(s):  
Trajectory Analysis ◽  
Eastern Mediterranean ◽  
Fungal Spores ◽  
Eastern Mediterranean Region ◽  
Inorganic Ions ◽  
Airborne Fungi ◽  
Back Trajectory ◽  
Back Trajectory Analysis ◽  
Biogenic Aerosols ◽  
Chemical Biomarkers

Abstract. Aerosols containing biological components can have a significant effect on human health by causing primarily irritation, infection and allergies. Specifically, airborne fungi can cause a wide array of adverse responses in humans depending on the type and quantity present. In this study we used chemical biomarkers for analyzing fungi-containing aerosols in the eastern Mediterranean region during the year 2009 in order to quantify annual fungal abundances. The prime marker for fungi used in this study was ergosterol, and its concentrations were compared with those of mannitol and arabitol which were recently suggested to also correlate with fungal spores concentrations (Bauer et al., 2008a). Back trajectory analysis, inorganic ions, humidity and temperature were used in an attempt to identify sources as well as the dependence on seasonal and environmental conditions. We found that the ambient concentrations of ergosterol, arabitol and mannitol range between 0 and 2.73 ng m−3, 1.85 and 58.27 ng m−3, 5.57 and 138.03 ng m−3, respectively. The highest levels for all biomarkers were during the autumn, probably from local terrestrial sources, as deduced from the inorganic ions and back trajectory analysis. Significant correlations were observed between arabitol and mannitol during the entire year except for the winter months. Both sugars correlated with ergosterol only during the spring and autumn. We conclude that mannitol and arabitol might not be specific biomarkers for fungi and that the observed correlations during spring and autumn may be attributed to high levels of vegetation during spring blossoms and autumn decomposing.

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