Use of CALIOP satellite data to explore the distribution and sources of organic aerosols in the troposphere

Abstract

Aerosols have been identifed as a contributor to the Earth's radiative budget. Aerosol emissions from human activities play a role at least as important as for the greenhouse gases. Their role is even more important that their global effect is opposite to the one of greenhouse effects: aerosols tend to cool down the atmosphere. Given that little scientifc attention has been put on the topic, many uncertainties remain. That is why many instruments have been developed these last years to improve our understanding on aerosols. One of them, the satellite Calipso has onboard the instrument Caliop providing unique measurements of the vertical distribution of aerosols. The aim of this thesis was to look at the spatial and vertical distribution across the globe of one specifc type of aerosols: the organic aerosols. Combining observations from Caliop and model predictions, through different algorithms written in MatLab, led to estimations on organic aerosol contribution to the total optical depth, as well as vertical profiles of extinction coefficients. What came out of this work is a good representation of the contribution of organic aerosols to the total optical depth around the world. Moreover contrary to what was expected, no recurrent seasonal pattern, nor similarity in the extinction vertical distribution were identified. However, it was also showed that the Emep aerosol model, used as the unique source of information about organic aerosols, can be improved as regarding the satellite data. Furher investigation in this direction could therefore lead to more accurate information on organic aerosol in terms of spatial and vertical distribution.