AEROSOL OPTICAL DEPTH FROM SPECTRAL DIRECT NORMAL IRRADIANCE MEASUREMENTS IN MONTEVIDEO, URUGUAY

Large-scale retrievals of the ultraviolet index (UVI) in real time by exploiting the modern Earth observation data and techniques are capable of forming operational early warning systems that raise awareness among citizens of the health implications of high UVI doses. In this direction a novel UVI operating system, the so-called UVIOS, was introduced for massive outputs, while its performance was tested against ground-based measurements revealing a dependence on the input quality and resolution.

The purpose of this work is to retrieve integrated water vapour using spectral measurements from Precision Solar Spectroradiometer (PSR). Two different approaches were developed one using single-channel direct sun irradiance measurements, and the second one integrating at a certain spectral region. The results of the spectral approach are closer to the retrievals of non-photometric techniques (GPS, microwave radiometer and radiosondes), suggesting this method provide more accurate IWV product.

Results of the temperature characterization of the global UV spectral measurements of eight different Brewer spectrophotometers operating in Greece, Finland, Germany and Spain are presented. Different temperature characterization methods are evaluated and an improved methodology for the correction of the measurements for the effects of temperature is presented.

Pollution aerosols strongly influence the composition of the Western Mediterranean, but at present little is known on their optical properties. Here, we report observations of pollution aerosols measured during the TRAQA airborne campaign in summer 2012. Data from this study indicate a large variability of the absorption for pollution particles. This variability strongly influences their direct radiative effect, with possible consequences on the hydrological cycle in this part of the basin.

Observations from this study indicate that continental pollution largely affects the atmospheric composition and structure of the western Mediterranean basin. Pollution plumes reach 3000-4000 m in altitude and present a very complex and highly stratified structure, characterized by fresh and aged layers both in the boundary layer and in the free troposphere. Also we report the observations of high levels of ultrafine particles over the basin, possibly linked to new particle formation events.