|کد مقاله||کد نشریه||سال انتشار||مقاله انگلیسی||ترجمه فارسی||نسخه تمام متن|
|5427001||1397241||2018||9 صفحه PDF||سفارش دهید||دانلود کنید|
- We measure degree of linear polarization of atmospheric aerosols over Vladivostok.
- In twilight we measure polarization of aerosols at different altitude (0-17â¯km).
- Umov law - inverse correlation of reflectance and polarization of scattered light.
- Using the Umov law we estimate reflectance in aerosol particles.
- Conclusions drawn with polarimetric technique are compared vs. lidar approach.
We report polarimetric measurements of atmospheric aerosol in evening and morning twilight over Vladivostok (Russia) in late winter-early spring of 2017 using a horizon-shadowing technique. Motion of the Sun beneath the horizon changes the altitude of the boundary of the shadowed atmosphere h, making it possible to constrain the altitude of aerosol particles contributing to the polarimetric response. We investigate the degree of linear polarization P in aerosol particles at different altitudes, ranging from 0â¯km up to 17â¯km. In two out of four experiments we found significant variations of the polarimetric response (ÎPÂ â¼Â 10%) with altitude; whereas, in the other measurements, the polarization appeared nearly the same (ÎPÂ â¼Â 2-3%) throughout the entire range of the studied altitude. Polarization P was measured in the zenith direction with the scattering angle being Î¸Â â¼Â 90Â° At such a scattering angle, the polarization is near its maximum value Pmax. We analyze our measurements using the Umov effect that describes an inverse correlation between Pmax and the geometric albedo A. On 2017-02-21, we estimate AÂ âÂ 0.0120â¯Â±â¯0.0004 at hâ¯=â¯0â¯km and AÂ âÂ 0.0154â¯Â±â¯0.0026 at hâ¯=â¯10â¯km. On 2017-02-27, we find the opposite trend, AÂ âÂ 0.0108â¯Â±â¯0.0003 (hâ¯=â¯0â¯km) and AÂ âÂ 0.0084â¯Â±â¯0.0006 (hâ¯=â¯10â¯km). On 2017-03-02 and 2017-03-03 we find AÂ â 0.0084â¯Â±â¯0.0009 and AÂ âÂ 0.0090â¯Â±â¯0.0010, respectively. Conclusions drawn from polarimetric measurements appear in qualitative accordance with results of remote sensing with a three-wavelength lidar.
Journal: Journal of Quantitative Spectroscopy and Radiative Transfer - Volume 204, January 2018, Pages 94-102