SAS scientists developed a new optical method for measuring atmospheric aerosols
For scientist, obtaining information about the atmospheric aerosol at night by optical methods has been very limited until recently. The vast majority of methods used so far use the presence of sunlight. The team of authors from the Slovak Academy of Sciences has created a new experimentally and economically undemanding method using which the experts from all over the world can study the properties of the atmospheric aerosol continuously during the day and at night. The work was published by the renowned journal Geophysical Research Letters.
The database containing the results of daily satellite and ground-based atmospheric aerosol measurements is extensive and already allows for global mapping of the microphysical properties of the aerosol. On the other hand, the nightly data that professionals can work with is minimal. The huge gap in the availability of day and night data and the lack of methods for systematic night optical aerosol monitoring are the main reasons why scientists have so far failed to comprehensively monitor dynamic processes in the aerosol system, such as its transformation and spread into the environment.
An international team from Slovakia, USA, Spain and Austria has developed the first direct method of determining the so-called phase function of atmospheric aerosol dispersion - i.e. properties, which describe the angular structure of the light field in the ground layer of the atmosphere.
"Of the known aerosol optical properties, only the total optical thickness of the atmosphere is routinely measured during clear nights at some ground stations. These methods are mostly indirect and require advanced measurement techniques,” explains Miroslav Kocifaj, the head of the research team from the Institute of Construction and Architecture SAS.
The new method uses a low-power laser operating in continuous mode. Systematic monitoring can be implemented using conventional, inexpensive and commonly available equipment.
"Our developed and experimentally tested method can be used routinely in virtually any location. It can be applied in naturally dark places, as well as in places with a high level of light pollution, under clear and cloudy skies,” explains the scientist.
Characterizing the properties of an atmospheric aerosol at night is a difficult challenge. It is of great importance not only for atmospheric studies but also for modelling the propagation of artificial light in the night atmosphere, which is an area of research with direct applications in ecology or light pollution management. The work of the team of SAS authors also gives experts new possibilities to predict the degree of penetration of light pollution into the environment as well as the overall level of ambient light, because both depend on the phase function of scattering. This is typically available at AERONET stations - in Slovakia, this is located only in Poprad-Gánovce.
The study is available at: https://doi.org/10.1029/2022GL098608.