Humidity transport from the Earth's surface into the atmosphere is relevant for many processes. However, knowledge of the actual distribution of humidity concentrations is sparse – mainly due to technological limitations. With the lidar presented herein, it is possible to measure humidity concentrations and their vertical fluxes up to altitudes of > 3 km with high spatiotemporal resolution, opening new possibilities for detailed process understanding and, ultimately, better model representation.

Optical remote sensing systems, so-called lidars, are used to learn more about aerosols, which play an important role in atmospheric processes. The present study demonstrates that lidars, which measure the backscattering behavior of aerosols over the entire visible wavelength range, can increase our knowledge of the spatial and temporal occurrence of aerosol layers, the type of aerosol, and their interaction with clouds. The focus of the publication is on wildfire aerosol and Saharan dust.

The 2021 volcanic eruption of Tajogaite on La Palma is investigated using ground-based and satellite measurements. In addition, the atmospheric transport of the volcanic cloud towards Europe is studied in detail. The amount of SO₂ released during the eruption and the height of the volcanic plume are in excellent agreement among the different measurements. Furthermore, volcanic aerosol microphysical properties could be retrieved using a new retrieval approach based on lidar measurements.

Estimating the impact of convection on the upper-tropospheric water budget remains a problem for models employing resolutions of several kilometers or more. A sub-kilometer high-resolution model is used to study summertime convection. The results suggest mostly close agreement with ground- and satellite-based observational data while slightly overestimating total frozen water path and anvil lifetime. The simulations are well suited to supplying information for parameterization development.