Key instruments for our studies are high-performance multiwavelength Raman lidars (lidar = light detection and ranging) distributed in various regions of the globe. Our current anchor points are instruments of the European Aerosol Research Lidar Network (EARLINET) and our lidar station at the Gwangju Institute of Science and Technology (GIST) in South Korea. Sun photometers, mainly operated by AERONET and star photometers are used for complementary aerosol studies. Data provided by NASA's A-Train and MISR satellites are used to extend our aerosol studies with ground-based instruments.
We also develop novel measurement technologies under laboratory conditions. The expertise we obtain from this work is used to develop novel measurement channels for lidar applications.
We are setting up a new research laboratory at CACP. The laboratory will focus on fundamental work in laser-spectroscopy methods. Our goal is to develop novel light-scattering based technologies that will allow us to use them in LIDAR-based remote sensing of aerosol pollution. This research work is supported by the Royal Society through the Royal Society Wolfson Research Merit Award.
We will use lasers as light source for carrying out experiments in which light-scattering processes are used to identify specific properties of atmospheric gases and particles. In the first stage we target Raman spectroscopy and fluorescence phenomena as primary source of signals from aerosol pollution. Our primary research targets are the identification of chemical components in aerosol pollution. It is not clear how precise this identification of chemical compounds will be. We have first experience with the identification and quantification of silicon dioxide which is an ideal tracer for mineral dust (Müller et al., 2010; Tatarov et al., 2011; Tatarov et al., 2012).
This new technology will in future allow us to identify the aerosol chemical composition on the basis of lidar measurements. This technique is different from the current method of so-called lidar-based aerosol typing. Aerosol typing rests upon the measurements of intensive aerosol properties as for example extinction-to-backscatter ratios (lidar ratios), Ångström exponents, and particle linear depolarization ratios. Depending on the type of pollution, e.g. smoke, urban haze, mineral dust, sea salt, volcanic ash, these intensive aerosol properties take different values. However, the range of values that is typically found for each aerosol type overlaps with values of other aerosol types. Thus, a clear identification of aerosol types may not always be possible under natural conditions. For that reason the ability to identify aerosol components, i.e. the chemical composition within aerosol types may allow us to improve aerosol characterization.
Aside from the application of this technology to aerosol pollution characterization we plan to explore these methods in their potential of identifying bacteria and pollen in the air. It is known that mineral dust carries bacteria. Dust outbreaks which frequently occur over East Asia and North Africa often cause serious health problems in the local population shortly after such outbreaks. There is an increase of hospital visits due to respiratory problem and other allergic reactions. Cases of meningitis are known to be caused by dust outbreaks in the Sahel zone in Africa. Fluorescence spectroscopy may be possible to identify the presence of bacteria on mineral dust which thus can be used in improved forecasting for allergy sufferers. The same can be said about pollen emissions which are a common phenomenon also in Europe throughout spring and summer each year. Our technique will be able to identify the presence of pollen. We want to explore the possibility of identifying a few important types of pollen in the air which would be of great benefit to allergy sufferers.
A third important component of our laboratory-based research work is to establish methods that can help reducing global crop loss. It is estimated that 16% of the annual crop yield is lost because fungi and spores destroy crop. There are not direct measurement methods available that allow us to identify the sources of these fungi and spores and that are able to track them in the air on a remote sensing basis. Any improved forecasting of the likely occurrence of fungi and spores could lead to the reduction of loss of crop yield. Climate change opens new transport pathways of these diseases to previously unaffected areas. Thus, there is a strong link between climate change and the far reaching consequences for society that arise from increasing temperatures on Earth.