## 2 Materials and Methods  
### Lidar Technology  
Lidar techniques offer a diverse range of capabilities for studying aerosols and clouds. Elastic lidar (EL), or elastic backscatter lidar, is one of the most widely used methods for detecting and profiling aerosols. It measures backscattered light at the same wavelength as the emitted laser pulse, providing valuable information on aerosol layers and their vertical structure [6; 16]. However, elastic lidar lacks the ability to derive specific aerosol properties, such as aerosol optical depth or extinction coefficient, without additional assumptions [17] or additional measurements. On the other hand, Raman lidar (RL) is a more sophisticated technique, named for the Raman scattering effect, that overcomes some of the limitations of elastic lidar. It measures the backscattered light at shifted wavelengths, which can be used to retrieve the aerosol extinction coefficient and other properties, without additional assumptions, such as the so-called lidar ratio [18; 19]. RL can also provide information on water-vapor mixing ratio profiles, which is an essential parameter for understanding the hydrological cycle and cloud-formation processes. High-spectral-resolution laser (HSRL, [20]) is another technology that, thanks to a high-resolution spectral filter, provides direct and independent measurements of aerosol optical properties due to extinction and backscatter, allowing for more precise investigations of aerosol layers. The Doppler wind lidar (DWL) technique presents a different approach from the other techniques listed above. Instead of relying solely on the intensity or polarization of backscattered laser light, the DWL technique specifically analyzes the frequency shift between the transmitted and received light spectrum. This frequency shift, often known as the Doppler shift, is induced by the motion of particles (such as aerosols or molecules) in the atmosphere with which the light interacts. By processing this frequency difference through interference filters, DWL can accurately retrieve the wind speed along the line of sight. This method offers precise and direct measurement of wind profiles, making it an invaluable tool in meteorological observations and forecasting [21]. Each of these techniques presents unique capabilities and limitations, and the choice between them often depends on the specific requirements of the aerosol and cloud studies that are being undertaken and, of course, the available budget. In recent years, the advancement of lidar technology has increased the complexity of the field. As a result, extensive research on retrieval and denoising methods has become crucial to retrieve the properties of aerosol layers and clouds [22]. Lidar technology is traditionally used to evaluate and obtain the optical, microphysical, and geometric characteristics of aerosols and clouds. Furthermore, it is utilized to determine wind speed profiles, evaluate turbulence, and study processes within the boundary layer, which is the section of the troposphere directly in contact with the Earth's surface. Lidars are adept at differentiating between various types of aerosols and clouds, particularly through the lidar volume depolarization channel. Irregularly shaped entities such as dust particles and ice crystals scatter light in a highly depolarized fashion. On the contrary, other aerosols and clouds, such as water droplets or biomass burning, are more spherical and result in reduced depolarization of scattered light [16; 23; 24]. Notably, the aerosol classifications in CALIPSO do not consist of distinct categories but are rather continuous mixtures, making the achieved level of agreement commendable. Another pivotal application of lidar technology is the determination of the thickness of the boundary layer. As [PERSON] elucidates [25], the boundary layer is the atmospheric layer directly affected by the Earth's surface and that reacts to its forcings within roughly an hour.