Impacto de las nubes de polvo sahariano sobre las medidas de la columna de ozono desde fotómetros orbitales orientados al nadir

Resumen

My PhD work consisted in studying the potential errors on satellite ozone measurements caused by high loads of UV absorbing aerosols like Saharan dust. With this aim, several products of total ozone column (TOC) such as those of TOMS, OMI, GOME, GOME 2 and SCIAMACHY were examined, with a particular emphasis on TOMS data. To study the influence of UV absorbing aerosols on satellite TOC data, two airborne campaigns (July 2005 and 2006) dedicated to this issue and taking place in the Canary Islands were conducted. Indeed, this area is known to be frequently affected by Saharan dust especially in summer. For the campaign periods, a detailed characterization of both ozone and aerosols was carried out by integrating data of many instruments (about 15) including both in-situ and remote sensing, with different platforms (aircraft, balloon, satellite) as well as ground-based stations. To generate the results obtained by TOMS v7 ozone algorithm, I had to develop an alternative code based on a NASA technical note. This alternative code which was written in Fortran, is using results of the LibRadtran radiative transfer model to simulate the satellite radiances as observed by the TOMS spectrometer, under different atmospheric scenarios. Besides, during the campaign, I had to analyze the results of three Saharan dust prediction models (DREAM, NAAPS and SKIRON), as well as those of the HYSPLIT trajectory model to provide dust pre-launch forecast bulletins for planning the aircraft flights. In addition to the campaigns results, the potential errors were also statistically investigated using long-term dataseries (up to 11 years) of total ozone column (satellite and ground-based data) and aerosol optical depth (ground-based spectrometer and sunphotometer data).