"Ultraviolet (UV) solar radiation has a broad range of effects concerning life on Earth. It influences not only human beings, but also plants and animals. Furthermore, it causes degradation of materials and functions as a driver of atmospheric chemistry. In order to study the UV related effects and their implications thoroughly; accurate information is needed on UV radiation intensities over the globe. The main overall scientific goal of this project is to search for improvements in estimating surface UV from satellite measurements (AURA/OMI, EUMETSAT/O3MSAF) and thus to decrease the uncertainty related to the globally available surface UV data, which is of importance and interest for a wide discipline of UV related studies. The above goal is planned to be achieved through the integration of measurements from different satellite sensors, which is likely the most feasible strategy for improving on the uncertainties related to UV radiation data. Major step of the project is to link aerosol and cloud retrievals from various (mainly A-Train) satellite sensors and also global scale modeling initiatives (AeroCom) with solar UV satellite retrievals, through the quantification of their effects on solar radiation reaching the earth’s surface. In addition, to increase the UV data end users, with emphasis on the Atmospheric chemistry research community introducing global products of photolysis frequencies of O¬zone and NO2. Using UV irradiance satellite/products, a modified method will be proposed for the retrieval of such parameters in a global scale. All, results will be validated against available quality assured ground-based measurements. Through this project the applicant aims to transfer the substantial experience in satellite-based instruments, global monitoring of atmospheric parameters and also ground-based atmospheric information analysis, from the Finnish Meteorological Institute to his new host institute (National Observatory of Athens, Greece)."