Measurement of aerosol optical depth in the Atlantic Ocean and Mediterranean Sea

1995 ◽  
Author(s):  
Alexander Smirnov ◽  
Oleg Yershov ◽  
Yuri Villevalde
Keyword(s):  
Atlantic Ocean ◽  
Mediterranean Sea ◽  
Aerosol Optical Depth ◽  
Optical Depth

scholarly journals Ship-based aerosol optical depth measurements in the Atlantic Ocean: Comparison with satellite retrievals and GOCART model

2006 ◽  
Vol 33 (14) ◽  
Author(s):  
A. Smirnov ◽  
B. N. Holben ◽  
S. M. Sakerin ◽  
D. M. Kabanov ◽  
I. Slutsker ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Satellite Retrievals ◽  
Gocart Model

scholarly journals Relationship between low-cloud presence and the amount of overlying aerosols

2016 ◽  
Author(s):  
Chul E. Chung ◽  
Anna Lewinschal ◽  
Eric Wilcox
Keyword(s):  
Pacific Ocean ◽  
Atlantic Ocean ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Satellite Observations ◽  
Wide Spread ◽  
Clear Sky ◽  
Northeastern Pacific ◽  
Low Cloud ◽  
Southeastern Atlantic

Abstract. Aerosols are often advected above cloud decks, and the amount of aerosols over cloud has been assumed to be similar to those at the same heights in nearby clear sky. In this assumption, cloud and aerosol above cloud top height are considered randomly located with respect to each other. The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data are analyzed here to investigate this assumption on global scales. The CALIPSO data reveal that the aerosol optical depth (AOD) above low cloud tends to be smaller than in nearby clear sky during the daytime and the opposite is true during the nighttime. In particular, over oceanic regions with wide-spread low cloud, such as the tropical southeastern Atlantic Ocean and northeastern Pacific Ocean, the daytime AOD above low cloud is often 40 % smaller than in surrounding clear skies.

scholarly journals Relationship between low-cloud presence and the amount of overlying aerosols

2016 ◽  
Vol 16 (9) ◽  
pp. 5781-5792 ◽  
Author(s):  
Chul Eddy Chung ◽  
Anna Lewinschal ◽  
Eric Wilcox
Keyword(s):  
Pacific Ocean ◽  
Atlantic Ocean ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Satellite Observations ◽  
Wide Spread ◽  
Clear Sky ◽  
Northeastern Pacific ◽  
Low Cloud ◽  
Southeastern Atlantic

Abstract. Aerosols are often advected above cloud decks, and the amount of aerosols over cloud has been assumed to be similar to that at the same heights in nearby clear sky. In this assumption, cloud and aerosol above cloud-top height are considered randomly located with respect to each other. The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data are analyzed here to investigate this assumption on global scales. The CALIPSO data reveal that the aerosol optical depth (AOD) above low cloud tends to be smaller than in nearby clear sky during the daytime, and the opposite is true during the nighttime. In particular, over oceanic regions with wide-spread low cloud, such as the tropical southeastern Atlantic Ocean and northeastern Pacific Ocean, the daytime AOD above low cloud is often 40 % smaller than in surrounding clear skies.

scholarly journals Saharan dust aerosol over the central Mediterranean Sea: PM<sub>10</sub> chemical composition and concentration versus optical columnar measurements

2014 ◽  
Vol 14 (4) ◽  
pp. 2039-2054 ◽  
Author(s):  
M. Marconi ◽  
D. M. Sferlazzo ◽  
S. Becagli ◽  
C. Bommarito ◽  
G. Calzolai ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Mediterranean Sea ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Saharan Dust ◽  
Central Mediterranean ◽  
Source Areas ◽  
Central Mediterranean Sea ◽  
Dust Events ◽  
The Eu

Abstract. This study aims to determine the mineral contribution to PM10 in the central Mediterranean Sea, based on 7 yr of daily PM10 samplings made on the island of Lampedusa (35.5° N, 12.6° E). The chemical composition of the PM10 samples was determined by ion chromatography for the main ions, and, on selected samples, by particle-induced X-ray emission (PIXE) for the total content of crustal markers. Aerosol optical depth measurements were carried out in parallel to the PM10 sampling. The average PM10 concentration at Lampedusa over the period June 2004–December 2010 is 31.5 μg m−3, with low interannual variability. The annual means are below the EU annual standard for PM10, but 9.9% of the total number of daily data exceeds the daily threshold value established by the European Commission for PM (50 μg m−3, European Community, EC/30/1999). The Saharan dust contribution to PM10 was derived by calculating the contribution of Al, Si, Fe, Ti, non-sea-salt (nss) Ca, nssNa, and nssK oxides in samples in which PIXE data were available. Cases in which crustal content exceeded the 75th percentile of the crustal oxide content distribution were identified as elevated dust events. Using this threshold, we obtained 175 events. Fifty-five elevated dust events (31.6%) displayed PM10 higher than 50 μg m−3, with dust contributing by 33% on average. The crustal contribution to PM10 has an annual average value of 5.42 μg m−3, and reaches a value as high as 67.9 μg m−3 (corresponding to 49% of PM10) during an intense Saharan dust event. The crustal content estimated from a single tracer, such as Al or Ca, is in good agreement with the one calculated as the sum of the metal oxides. Conversely, larger crustal contents are derived by applying the EU guidelines for demonstration and subtraction of exceedances in PM10 levels due to high background of natural aerosol. The crustal aerosol amount and contribution to PM10 showed a very small seasonal dependence; conversely, the dust columnar burden displays an evident annual cycle, with a strong summer maximum (monthly average aerosol optical depth at 500 nm up to 0.28 in June–August). We found that 71.3% of the dust events identified from optical properties over the atmospheric column display a high dust content at the ground level. Conversely, the remaining 28.7% of cases present a negligible or small impact on the surface aerosol composition due to the transport processes over the Mediterranean Sea, where dust frequently travels above the marine boundary layer, especially in summer. Based on backward trajectories, two regions, one in Algeria–Tunisia, and one in Libya, are identified as main source areas for intense dust episodes occurring mainly in autumn and winter. Data on the bulk composition of mineral aerosol arising from these two source areas are scarce; results on characteristic ratios between elements show somewhat higher values of Ca / Al and (Ca + Mg) / Fe (2.5 ± 1.0, and 4.7 ± 2.0, respectively) for Algeria–Tunisia than for Libyan origin (Ca / Al = 1.9 ± 0.7 and (Ca + Mg) / Fe = 3.3 ± 1.1).

The Impact of Dust Storms on Aerosol Optical Depth and Radiative Forcing

2020 ◽  
Vol 16 (1) ◽  
pp. 1-14
Author(s):  
Monim Jiboori ◽  
Nadia Abed ◽  
Mohamed Abdel Wahab
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Radiative Forcing ◽  
Dust Storms ◽  
The Impact

Aerosol optical depth at ALOMAR Observatory (Andøya, Norway) in summer 2002 and 2003

Tellus B ◽  
2006 ◽  
Vol 58 (3) ◽  
Author(s):  
Carlos Toledano ◽  
Victoria Cachorro ◽  
Alberto Berjón ◽  
Mar Sorribas ◽  
Ricardo Vergaz ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth
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