Thesis of Maria Fernanda-Sanchez

Defense of thesis Maria Fernanda-Sanchez  - Laboratory LOA

Development of an autonomous integrated mobile system combining lidar and photometer to monitor aerosol properties in near real time

Abstract :

Improving our understanding of aerosols spatio-temporal distribution and their impact at local, regional, and global scales, while minimizing uncertainties in their properties, is crucial for accurately assessing their radiative effects. To this end, lidar and photometer are convenient tools for aerosol monitoring, enhanced by the development of networks. However, laboratories in fixed sites are restricted by their local conditions and position with respect to the aerosol sources. Thus, the deployment of mobile laboratories (aboard ship cruises, airplanes or cars) provided a solution to fill these observational gaps within networks. The first experiences using a single-wavelength elastic lidar and sun-photometer have demonstrated the feasibility of in-motion observations and highlighted ongoing technical challenges to be addressed. Therefore, the lightweight CIMEL CE376 lidar, which provides measurements at 532 nm and 808 nm and depolarization at 532 nm, is coupled with the CE318-T sun/moon photometer to enhance mobile aerosol monitoring. Both instrumental and algorithmic assessments were conducted at ATOLL (ATmospheric Observatory of liLLe) platform operated at the Laboratoire d’Optique Atmosphérique (LOA), in Lille, France. In particular, algorithmic developments are proposed to retrieve aerosols properties from the CE376 lidar measurements, envisioning near real time analysis. Data acquired at two sites, ATOLL and IZO (Izaña Observatory, Tenerife, Spain), were therefore analyzed through case studies under presence of different aerosol types (mineral dust, mineral dust-smoke, volcanic ash and sulfates), showcasing, in this way, the capabilities of the lidar system to characterize aerosols. Moreover, a first dataset of CE376 lidar and photometer performing on-road measurements was obtained during the FIREX-AQ (Fire Influence on Regional to Global Environments and Air Quality) field campaign, deployed in summer 2019 over the Northwestern USA. Despite the extreme environmental conditions, the study of smoke aerosols near fire sources was enabled by lidar and photometer mapping in 3D. The future implications of a ship-borne CE376 lidar is also presented, by means of showcase from a single-wavelength lidar aboard the Marion Dufresne research vessel during the AMARYLLIS-TRANSAMA campaign in 2023. This work provides a comprehensive discussion on the capabilities (and limitations) of the CE376 lidar in bridging observational gaps in aerosol monitoring, providing valuable insights for future research in this field.

Keywords : atmosphere,aerosols,remote sensing,mobile observations,lidar,photometer