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not work, such as over snow and in cloudy situations (Winker et al. 2010 ). More
generally the information about the vertical layering of aerosols provided by lidar
instruments is crucial for aerosol-cloud interaction studies.
Systematic ground-based desert dust observations by lidar through networks
are mainly located over two regions of interest: the Mediterranean Europe and
Asia (Mona et al. 2012 ). Some recent studies have investigated dust vertical
distributions over other less explored regions like Iran, but only in the form of
case studies analysis (Abdi Vishkaee et al. 2011 ). The European Aerosol Research
Lidar Network, EARLINET, was established in 2000 and provides systematic
observations of Saharan dust events over several stations of the European continent
(27 in 2012; Mona et al. 2012 ). Based on EARLINET data, Papayannis et al.
( 2008 ) showed that more than 130 days of Saharan dust outbreaks were monitored
over Europe in 3 years, with the largest number of cases from late spring until
early autumn months, and a much higher number of dust episodes observed in
the southern parts of Europe. Continuous observations of vertical distribution and
optical properties of Asian dust in East Asia (China, Korea, Japan and Mongolia)
are made by depolarization and backscatter lidars with AD-Net (Mona et al. 2012 ).
Müller et al. ( 2010 ) have shown that one of the important characteristics of Asian
dust is the mixing of mineral dust with anthropogenic pollution.
7.4
Conclusion
For many remote areas of the globe, the only approach for quantitative and
continuous dust observations is via satellites. With the advances in remote sensing
measurements, a revolution in aerosol and dust monitoring has been taking place
in recent years (Laj et al. 2009 ;Shaoetal. 2011 ;Yuetal. 2013 ). Thanks to
progress in both technology and algorithm development from active and passive
sensors, the number and quality of observations of AOD and the optical properties
of dust have considerably increased during the last decades (Redmond et al. 2010 ).
Our current knowledge of the global distribution of mineral dust is for a good
part based on satellite observations with passive remote sensors like AVHRR,
MODIS, TOMS, Meteosat, MISR, POLDER and SeaWiFS. Since the launch of the
CALIPSO mission in 2006, a global view of height-resolved dust distribution has
become possible (Liu et al. 2008b ). Moreover, the emerging satellite observations
of above-cloud aerosols, from both spaceborne lidar and passive sensors, especially
from the A-Train, certainly constitute a major advancement of the very recent years
(Yu and Zhang 2013 ).
Compared to early sensors in operation in the 1990s, the last generation of satel-
lites has better observing capabilities for dust, especially SEVIRI/MSG, MODIS,
MISR, POLDER and CALIOP, allowing deeper understanding of aerosol processes
in terms of emission and transport. Furthermore, with the most recent satellite
algorithms from MODIS (Ginoux et al. 2012 ), POLDER (Herman et al. 2005 )and
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