Vol. 39, issue 08, article # 11

Abstract:

Cirrus clouds cover a significant part of the Earth's surface and have a significant impact on the radiation balance and climate. To calculate the solar radiation transmittance of clouds, it is necessary to control the optical thickness of clouds. Lidar sensing is an optimal method for this. The paper compares two lidar methods for determining the optical thickness τ of cirrus clouds, using elastic or Raman scattering signals. Both techniques are based on recording signals from the clear atmosphere down to and above a сloud, but the use of elastic scattering is associated with errors caused by the possible presence of sub-cloud or above-cloud aerosol layers. Different methods for processing experimental data were compared, and the error in determining the optical thickness was assessed. It is shown that deviations in retrieving the thickness from elastic scattering signals can attain ~ 0.5 for clouds with the optical thickness τ > 2. At τ ≤ 1, the correlation coefficient between the data of the two methods is 0.94, which enables the use of elastic scattering signal measurements, available even during daytime, to estimate the optical thickness of cirrus clouds. The results of the work can be used in the development of lidar systems for sensing upper-level clouds.

Keywords:

lidar, aerosol, crystalline clouds, optical depth, elastic and Raman scattering

References:

1. Zuev V.E., Titov G.A. Optika atmosfery i klimat / pod red. akad. V.E. Zueva. Tomsk: Spektr IOA SO RAN, 1996. V. 9. 271 p.
2. Feigel'son E.M. Luchistyi teploobmen i oblaka. L.: Gidrometeoizdat, 1970. 230 p.
3. Shifrin K.S. Rasseyanie sveta v mutnoi srede. M.; L.: Gostekhteorizdat, 1951. 288 p.
4. Volkovitskii O.A., Pavlova L.N., Petrushin A.G. Opticheskie svoistva kristallicheskikh oblakov. L.: Gidrometeoizdat, 1984. 200 p.
5. Konoshonkin A.V., Shishko V.A., Kustova N.V., Liu D., Wang Z., Timofeev D.N., Tkachev I.V., Salnikov K.S., Zhu X., Wang Y. ScIce-2023 – bank dannykh matrits obratnogo rasseyaniya sveta dlya ledyanykh kristallov peristykh oblakov dlya interpretatsii dannykh lazernogo zondirovaniya // Optika atmosf. i okeana. 2025. V. 38, N 8. P. 665–6724. DOI: 10.15372/AOO20250810; Konoshonkin A.V., Shishko V.A., Kustova N.V., Liu D., Wang Z., Timofeev D.N., Tkachev I.V., Salnikov K.S., Kan N., Zhu X., Wang Y. ScIce-2023 Database of backscatte­ring Mueller matrices of ice crystals of cirrus clouds for lidar applications // Atmos. Ocean. Opt. 2025. V. 38, N 6. P. 751–758.
6. Radiatsiya v oblachnoi atmosfere / pod redaktsiei E.M. Feigel'son. L.: Gidrometeoizdat, 1981. 280 p.
7. Kovalev V.A., Eichinger W.E. Elastic Lidar. New Jersey: J. Willey & Sons, 2004. 615 p.
8. Balin Yu.S., Kokhanenko G.P., Klemasheva M.G., Penner I.E, Nasonov S.V., Samoilova S.V. «LOZA-S» – bazovyi lidar rossiiskogo segmenta lidarnykh stantsii seti SNG (CIS LiNet) // Optika atmosf. i okeana. 2017. V. 30, N 12. P. 1065–1068. DOI: 10.15372/AOO20171210.