Caracterización de los aerosoles atmosféricos en Valencia mediante fotometría solar.

Abstract

There is a real need on improving our knowledge of the physical and optical properties of the atmospheric particles. These particles (called aerosols) are important on the atmosphere and Earth systems. Their effect on the climate prediction is decisive, and moreover they degrade the quality of remote sensed images. Therefore, this work is aimed at characterising the climatological properties of the atmospheric aerosols, and their transport mechanisms. For this purpouse, we have applied sunphotometry experimental technics in a site located in the suburbs of Valencia city at the east coast of Spain. For the aerosol properties retrieval, we have employed two automatic CIMEL sunphotometers, model CE318. This equipment measures solar direct radiation and sky diffuse radiance. On the other hand, there are few inversion algorithms for deriving the optical properties from the sun sky sunphotometer measurements. The one employed in this work has been Skyrad.Pack. This algorithm retrieves the aerosol size distribution function, scattering phase function, single scattering albedo, complex refractive index and asymmetry parameter. The results of this work have been divided in three parts. In the first one the instrumentation has been characterised: calibration monitoring of the direct and diffuse components, thermal effects on the sensors and its correction, and a novel correction method for accounting for lateral deviation of the solar pointing. These corrections introduce an important improvement on the results. A second part is devoted to the climatological characterisation of the aerosols in the suburban area of Valencia. The annual, seasonal and monthly trends are also analysed, with a detailed statistical study. The third part is aimed at finding a relationship between the dominant air masses geographical origins and the particles properties, as they are brought by the air masses from remote source areas. Finally, a large number of tables have been also prepared and presented at the appendix for consultation, when climatological or remote sensing studies must be done at regions in western Europe, that are affected by pollution from medium size cities and also by maritime or north african air masses.