Potential of polarization lidar to provide profiles of CCN- and INP-relevant aerosol parameters
We investigate the potential of polarization lidar to provide vertical profiles of aerosol parameters from which cloud condensation nucleus (CCN) and ice nucleating particle (INP) number concentrations can be estimated. We show that height profiles of particle number concentrations <i>n<...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-05-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/16/5905/2016/acp-16-5905-2016.pdf |
| Summary: | We investigate the potential of polarization lidar to provide vertical
profiles of aerosol parameters from which cloud condensation nucleus
(CCN) and ice nucleating particle (INP) number concentrations can be
estimated. We show that height profiles of particle number concentrations <i>n</i><sub>50, dry</sub> considering
dry aerosol particles with radius > 50 nm (reservoir
of CCN in the case of marine and continental non-desert aerosols), <i>n</i><sub>100, dry</sub> (particles with dry radius > 100 nm,
reservoir of desert dust CCN), and of <i>n</i><sub>250, dry</sub> (particles with dry radius > 250 nm, reservoir of favorable INP),
as well as profiles of the particle surface area concentration <i>s</i><sub>dry</sub> (used in INP
parameterizations) can be retrieved from lidar-derived aerosol
extinction coefficients <i>σ</i> with relative uncertainties of a factor
of 1.5–2 in the case of <i>n</i><sub>50, dry</sub> and <i>n</i><sub>100, dry</sub> and of about 25–50 %
in the case of <i>n</i><sub>250, dry</sub> and
<i>s</i><sub>dry</sub>. Of key importance is the potential of polarization lidar to
distinguish and separate the optical properties of desert aerosols from non-desert aerosol such as continental
and marine particles. We investigate the relationship
between <i>σ</i>, measured at ambient atmospheric conditions, and <i>n</i><sub>50, dry</sub> for marine and continental aerosols, <i>n</i><sub>100, dry</sub>
for desert dust particles, and <i>n</i><sub>250, dry</sub> and <i>s</i><sub>dry</sub>
for three aerosol types (desert, non-desert continental, marine) and for the main lidar
wavelengths of 355, 532, and 1064 nm. Our study is based on multiyear Aerosol
Robotic Network (AERONET) photometer observations of aerosol optical
thickness and column-integrated particle size distribution at Leipzig,
Germany, and Limassol, Cyprus, which cover all realistic aerosol
mixtures. We further include AERONET data from field campaigns in
Morocco, Cabo Verde, and Barbados, which provide pure dust and pure
marine aerosol scenarios. By means of a simple CCN parameterization (with <i>n</i><sub>50, dry</sub> or <i>n</i><sub>100, dry</sub> as input) and
available INP parameterization schemes (with <i>n</i><sub>250, dry</sub> and <i>s</i><sub>dry</sub> as input) we finally compute profiles of
the CCN-relevant particle number concentration <i>n</i><sub>CCN</sub>
and the INP number concentration <i>n</i><sub>INP</sub>. We apply the method to a lidar observation of
a heavy dust outbreak crossing Cyprus and a case dominated by continental aerosol pollution. |
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| ISSN: | 1680-7316 1680-7324 |