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Stable polar vortex over Antarctica represented by the potential vorticity (PV) at 475 K-level on 24 June 2010. The white line indicates the edge of the polar vortex. Also shown are the location of Belgrano II station (Argentina, 77.9 • S 34.6 • W) together with Syowa (Japan, 69.0 • S 39.5 • E), which is outside the polar vortex edge, and South Pole/Amundsen-Scott (USA, 89.98 • S 24.8 • E) stations.
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Polar Stratospheric Clouds (PSCs) play an important role in polar ozone depletion. In particular ice clouds, type PSC-II, with respect to the type PSC-I (nitric acid clouds) produce the most significant effects. Therefore PSC characterization, mainly focused on PSC-II discrimination is needed. The backscattering (R) and volume linear depolarization...
Contexts in source publication
Context 1
... Sigma Space Corp.), which includes a built-in depolarization measurement module, is currently used for PSC observations in the Antarctic Belgrano II station (Argentina, 77.9 • S 34.6 • W, 256 m a.s.l.) since 2009. The column of air above this station remains well inside the polar 20 vortex during wintertime ( Parrondo et al., 2007), as shown in Fig. 1 in relation to the Antarctic polar vortex on 24 June 2010, providing thus an excellent location for PSC observations. Older versions than the MPL-4 have already been deployed in two other Antarctic stations (see Fig. 1): Syowa (Japan, 69.0 • S 39.5 • E), where a PSC type-II sin- gle event was reported and attributed to low temperature ...
Context 2
... column of air above this station remains well inside the polar 20 vortex during wintertime ( Parrondo et al., 2007), as shown in Fig. 1 in relation to the Antarctic polar vortex on 24 June 2010, providing thus an excellent location for PSC observations. Older versions than the MPL-4 have already been deployed in two other Antarctic stations (see Fig. 1): Syowa (Japan, 69.0 • S 39.5 • E), where a PSC type-II sin- gle event was reported and attributed to low temperature fluctuations related to inertia 25 gravity waves ( Shibata et al., 2003), and remaining usually outside the polar vortex (see Fig. 1 MPL-3 with careful smoothing procedures (Campbell and Sassen, 2008). However, none of ...
Context 3
... Older versions than the MPL-4 have already been deployed in two other Antarctic stations (see Fig. 1): Syowa (Japan, 69.0 • S 39.5 • E), where a PSC type-II sin- gle event was reported and attributed to low temperature fluctuations related to inertia 25 gravity waves ( Shibata et al., 2003), and remaining usually outside the polar vortex (see Fig. 1 MPL-3 with careful smoothing procedures (Campbell and Sassen, 2008). However, none of them include polarization measuring capabilities similar to those of the MPL-4. A good performance of the MPL-4 system for PSC detection was previously achieved in the Arctic (C ´ ordoba- Jabonero et al., 2009), where depolarization data confirmed ...
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... Hence, to our knowledge, 2λ polarization lidar experiments have only been used to observe two-component particle mixtures (Sugimoto and Lee, 2006; Tesche et al., 2009). In this Special Issue on the depolarization of light by atmospheric particles, polarization lidar measurements have been performed on polar stratospheric clouds (Jabonero et al., 2013), and numerical simulations are proposed to study the depolarization of light by ice cylinders (Nicolet et al., 2012 ), while laboratory measurements have been performed to study small ice crystals (Schnaiter et al., 2012) and dust particles (Glen et al., 2013 ). Our contribution, dedicated to the polarization (π) and spectral (λ) properties of atmospheric nonspherical particles after long-range transport, combines 2λ polarization lidar measurements with numerical light-scattering simulations. ...
During transport by advection, atmospheric non-spherical particles, such as volcanic ash, desert dust or sea-salt particles experience several chemical and physical pro-cesses, leading to a complex vertical atmospheric layering at remote sites where intrusion episodes occur. In this paper, a new methodology is proposed to analyse this complex ver-tical layering in the case of a two/three-component particle external mixtures. This methodology relies on an analysis of the spectral and polarization properties of the light backscat-tered by atmospheric particles. It is based on combining a sensitive and accurate UV-VIS polarization lidar experiment with T-matrix numerical simulations and air mass back tra-jectories. The Lyon UV-VIS polarization lidar is used to ef-ficiently partition the particle mixture into its nonspherical components, while the T-matrix method is used for simulat-ing the backscattering and depolarization properties of non-spherical volcanic ash, desert dust and sea-salt particles. It is shown that the particle mixtures' depolarization ratio δ p differs from the nonspherical particles' depolarization ratio δ ns due to the presence of spherical particles in the mixture. Hence, after identifying a tracer for nonspherical particles, particle backscattering coefficients specific to each nonspher-ical component can be retrieved in a two-component external mixture. For three-component mixtures, the spectral proper-ties of light must in addition be exploited by using a dual-wavelength polarization lidar. Hence, for the first time, in a three-component external mixture, the nonsphericity of each particle is taken into account in a so-called 2β + 2δ formal-ism. Applications of this new methodology are then demon-strated in two case studies carried out in Lyon, France, related to the mixing of Eyjafjallajökull volcanic ash with sulfate particles (case of a two-component mixture) and to the mix-ing of dust with sea-salt and water-soluble particles (case of a three-component mixture). This new methodology, which is able to provide separate vertical profiles of backscattering coefficient for mixed atmospheric dust, sea-salt and water-soluble particles, may be useful for accurate radiative forcing assessments.
During transport by advection, atmospheric nonspherical particles, such
as volcanic, desert dust or sea-salt particles experience several
chemical and physical processes, leading to a complex vertical
atmospheric layering at remote sites where intrusion episodes occur. In
this contribution, a new methodology is proposed to analyze this complex
vertical layering in the case of a two/three-component particle external
mixtures after long-range transport. This methodology relies on a
precise analysis of the spectral and polarization properties of the
light backscattered by atmospheric particles. It is based on combining a
sensitive and accurate UV-VIS polarization Lidar experiment with
accurate T-matrix numerical simulations and air mass back-trajectories.
The Lyon UV-VIS polarization Lidar is used to efficiently partition the
particle mixture into its nonspherical components, while the T-matrix
algorithm is used for computing backscattering and depolarization
properties specific to nonspherical volcanic, desert dust and sea-salt
particles, the latter being described in the cubic shape approximation.
It is shown that, after long-range transport, the particle mixtures'
depolarization ratio δp differs from the nonspherical
particles' depolarization ratio δns due to the presence
of spherical particles in the mixture. Hence, after identifying a tracer
for nonspherical particles, particle backscattering coefficients
specific to each nonspherical component can be retrieved in a two
component external mixture. For three-component mixtures, the spectral
properties of light must in addition be addressed by using a
dual-wavelength polarization Lidar. Hence, for the first time, in a
three-component external mixture, the nonsphericity of each particle is
taken into account in a so-called 2β + 2δ formalism.
Applications of this new methodology are then demonstrated in two case
studies carried out in Lyon, France, related to the mixing of
Eyjafjallajökull volcanic ash with sulphate particles (case of a
two-component mixture) and to the mixing of dust with sea-salt and
water-soluble particles (case of a three-component mixture). This new
methodology, which is able to provide separate vertical profiles of
mixed atmospheric dust, sea-salt and water-soluble particles, may be
useful for accurate radiative forcing assessments.
