Light Backscattering by Atmospheric Particles: From Laboratory to Field Experiments

Abstract

Atmospheric particlesAtmospheric particles may somewhat counterbalance the global warming effect of the Earth’s atmosphere due to greenhouse gases by directly contributing to the Earth’s climate through light scattering and absorption processes. According to the IPCCIPCC report (IPCC in Climate change 2013: the physical science basis. New York: Cambridge Univ. Press, 2013), the contribution of such particles to the Earth’s radiative budget however remains difficult to handle and quantify, mainly due to the complexity of these particles, which present a wide range of sizes, shapes and complex refractive indices. To face such a complexity, a major source of global data on these particles is provided by ground-based and satellite-based lidar remote sensingLidar remote sensing instruments, which are based on light backscatteringLight backscattering and extinction by atmospheric particlesAtmospheric particles. In this context, this book chapter proposes to present some recent advances in the field of light backscatteringLight backscattering by complex-shaped atmospheric particlesAtmospheric particles at specific backward scattering angle ( $$\theta =\pi$$ ) at which lidar instruments operate, for the first time to our knowledge in laboratory where a π-polarimeter has been built and operated for aerosolsAerosol (Miffre et al. in J Quant Spectrosc Radiat Transf 169:79–90, 2016; Miffre et al. in J Quant Spectrosc Radiat Transf 222–223:45–59, 2019b; Miffre et al. Atmos Meas Tech, 2022). These papers are the results of a team work in which Prof. Rairoux’s expertise in lidar remote sensingLidar remote sensing and laser spectroscopy played a key role. This work also owes much to former PhD students, G. David and D. Cholleton, who also played a key role. Laboratory experiments at near ( $$\theta <\pi )$$ backscattering angles are likewise proposed in complement as well as cooperative works with ONERA (Paulien et al. in J Quant Spectrosc Radiat Transf 260, 2021) and chemical colleagues from Lyon University (France) and North Carolina University (USA) (Dubois et al. in Phys Chem Chem Phys 23:5927–5935, 2021) to explore light backscatteringLight backscattering by complex-shaped particles. The benefits of this new laboratory approach, in comparison with existing light scattering numerical simulations and lidar field experiments, is discussed. We hope this book chapter will improve our understanding of the complex physical process of light backscatteringLight backscattering by atmospheric particlesAtmospheric particles, to in turn improve our understanding of the radiative properties of complex-shaped atmospheric particlesAtmospheric particles, to provide answer to radiative transfer issues.