Aerosol @ IGP PAS

Abstract:
1. Research project objectives/Research hypothesis
The main goal of the project is to investigate the influence of aerosols’ optical properties vertical profiles on generation of photochemical smog and exposure of the population to the solar UV radiation. To this end utilization of a synergy between LIDAR and sun-photometric technique is planned. Profiles of aerosols’ optical properties, retrieved at two locations, Belsk and Raciborz, will be used to calculate UV radiation intensity and estimate health risks of UV overdoses. The measured profiles will be supplied to the existing models of chemical weather to investigate their influence on surface ozone concentrations. Simulations of photochemical smog formation will be performed with the measured data instead of climatological one.
Hypothesis: The utilization of the retrieved vertical profiles of aerosols’ optical properties, instead of the commonly used climatological values, should allow for an improvement in the agreement between numerical models of both radiative transfer and chemical weather and the ground based measurements of UV index and ozone concentration.
2. Research project methodology
Synergic use of LIDARs and Sun-photometers will be applied to retrieve profiles of aerosols’ opticalproperties. Use of GARLiC algorithm (Lopatin et al., 2013), which is a part of GRASP-Open packageis planned. Such an algorithm allows to retrieve profile of bimodal aerosol size distribution as well as refractive index for each mode. These aerosol properties will be used to calculate profiles of aerosol extinction coefficient and single scattering albedo, parameters necessary for radiative transfer calculations. The variability of surface UV radiation (UV index) will be calculated by the means of Libradtran and TUV radiative transfer models with the use of the measured aerosol profiles. Modelled UV radiation (with the measured and climatological profiles) will be compared to that measured by IGF PAS UV monitoring network. Photochemical smog episodes will be identified by an analysis of surface ozone concentrations measured at IGF PAS stations. The measured concentrations will be compared to those modelled by GEM-AQ chemical weather model (Kaminski et al., 2008). Real (measured) and standard (climatological) aerosols’ profiles will be used for modelling of photochemical smog. In both the cases (UV index and smog) an improved agreement between the modelled and the measured values is expected. Evaluation of the quality of this improvement will be done for different types of aerosols and air masses. Model sensitivity study will be done by analysis of which configuration of aerosols’ properties yields the largest changes in the modelled parameters. Both UV radiation and ozone concentrations will be compared to the standard configuration of the model.
3. Expected impact of the research project on the development of science
Standard, climatological profiles of aerosol optical properties are currently used in radiative transfer calculations for chemical weather and UV index forecasting. Vertical profiles of aerosols size distributions, along with refractive indexes obtained with this project, will allow to determine the necessary vertical structure of aerosols’ properties that will be an input parameter for radiative transfer models and chemical weather forecast systems. Use of the measured, real profile of aerosols’ optical properties, especially properties of absorbing aerosols, will improve modelling of solar irradiation which is used for estimation of health effect of UV overdoses. Similarly, in case of chemical weather forecasting use of measured profiles will allow for better estimation of photo-dissociation rates and consequently an improved quality of chemical weather predictions. Cases study of extreme events will allow for better understanding of influence of aerosols’ properties profiles on photochemical smog formation. It will be investigated how properties of different types of aerosols at different altitudes affect surface UV radiation and extreme (smog) surface ozone concentrations.