Mercredi 23 mai 2018, 10:00

bibliothèque du LOA (bâtiment P5, 3ème étage, salle 336), Université de Lille

 

10:00

Igor VESELOVSKIY

Physics Instrumentation Center of GPI,
Troitsk, Moscow, Russia

 

 

10:45

Detlef MUELLER

University of Hertfordshire, Hatfield,
Hertfordshire, United Kingdom

 

Potential of multiwavelength lidar for the analysis of aerosol mixtures

 

Lidar Spectroscopy Instrument (LiSsI): status and future work

Inversion of multiwavelength lidar measurements allows to estimate the bulk properties of the aerosol. However, for climate modeling it is important to have information about components of the aerosol mixture. In particular, it is important to separate the fine and the coarse fractions, as well as the particles with low and strong absorption. Such separation can be made relying on the optical properties of five main aerosol components used in the MERRA-2 aerosol transport model: dust, black carbon, organic carbon, sulfates and sea salt. However, the properties of real aerosols present a lot of diversity and there is always a question, if the model parameters can be used for the case of interest. One of the issues is spectral dependence of the complex refractive index. In particular, the imaginary part of organic carbon and dust may present strong enhancement in UV region. Another issue is dependence of particle properties on the relative humidity (RH). To verify model, the lidar ratios of the MERRA-2 aerosol components are compared with results of lidar observations performed during SHADOW campaign in West Africa for different aerosol scenarios and for different values of RH. The chosen model optical properties of the components are used for aerosol mixture analysis.

 

 

 

 

 

We developed a complex inelastic lidar spectrometer that will be used for vertically-resolved observations of chemical components in atmospheric particles, trace gases, and biological material to at least tropopause heights. Main goals of our work include investigations of the effect of aerosol pollution on, e.g. the light-absorption capacity of the atmosphere, modifications of cloud properties that result from effects of aerosol chemistry, and in a broader context the impact of particles and reactive-trace gases on climate forcing, air quality, human health, and food production.

We use an ultra-high energy laser source and highly resolving spectrometer technology to achieve this goal. This lidar spectrometer will allow for vertically and spectrally resolved measurements of Raman and photoluminescence (PL)/fluorescence spectra. In contrast to first attempts carried out in the 1970s, opto-electronics technology has matured in the past 40 years to the point that this research work finally seems feasible.

The first stage of research work has begun. Measurements of pollution plumes in the atmosphere over the University of Hertfordshire, near London are used to test the key components of the optical and electronic components of LiSsI. We also started with tests on bio-aerosols under laboratory conditions.

The presentation will provide an overview on the status a) of instrument development, b) our research plan which includes combining information on aerosol chemistry with microphysical properties of particulate pollution, and c) first results of test measurements.

 

 

 

date: 
Mercredi, 23 Mai, 2018 - 10:00