Article mis en ligne le 25/02/2019
Aerosol layers in the UTLS (Upper Troposphere/Lower Stratosphere) were observed between 23 August and 12 September 2017. We identified the source of the UTLS aerosol layers using the measurements of different satellite sensors and revealed that the UTLS aerosol layers were transported from Canada to Europe by UTLS advection. LILAS multi-wavelength Raman Lidar system and sun photometer, part of the Lille Atmospheric Platform, recorded this event. In this study, we derived optical properties estimated from Lidar measurements in the week of 24–31 August: aerosol optical depth of the UTLS aerosol layers, Lidar ratios at 355 and 532 nm and particle linear depolarization ratio at three wavelengths (355, 532 and 1064 nm). Optical depth of the UTLS layer during considered period varies from 0.05 to more than 0.20 (532 nm), with very weak spectral dependence between 355 and 532 nm. Lidar ratio at 355 nm ranges from 31±15 sr to 45±9 sr and at 532 nm, Lidar ratio varies from 54±12 sr to 58±9 sr. Particle depolarization ratio decreases as wavelength increases with 23±3%–28±4% (355 nm), 18±3–20±3% % (532 nm) and 4.0±0.6%–5.0±0.8% (1064 nm). The retrievals derived the effective radius 0.33±0.10 µm. The complex refractive indices retrieved are 1.55 (±0.05)+I 0.028(±0.014). The simulations derived daily averaged net forcing of -13.2 W/m2 on the surface.
Hu Qiaoyun, P. Goloub, I. Veselovskii, J.-A. Bravo-Aranda, I. E. Popovici, T. Podvin, M. Haeffelin, A. Lopatin, O. Dubovik, C. Pietras, X. Huang, B. Torres, C. Chen, Long-range-transported Canadian smoke plumes in the lower stratosphere over northern France, Atmos. Chem. Phys., 19, 1173–1193, 2019, https://doi.org/10.5194/acp-19-1173-2019
Research supported by IDEAS/ESA programme and Labex CaPPA.