Seminar

Abstract

Among natural sources, marine emissions play a critical role in our understanding of climate. It has been shown recently that sea spray emissions depend on sea surface temperature (SST) in addition to wind speed and waves. Climate models predict an SST increase of 2 to 4°C in the Tropics and Subtropics by 2100, with the largest increase expected in the Indian and Pacific Oceans. Reunion Island (55W, 21S) in the Southern Indian Ocean is most of the time in a pristine marine environment with a clear seasonal cycle in marine primary production. However, depending on the weather situation and season, biomass burning plumes from Africa can sometimes be measured in the free troposphere. Hence, measurements taken from Reunion Island, and at the multi-instrumented Maido Observatory (2.2 km asl) in particular, are relevant for several topics related to marine aerosols, pristine oceanic regions and long-range transport of biomass burning plumes.

We will present preliminary results on the chemical composition of the tropical troposphere measured at Maido Observatory based on in-situ, balloon and LIDAR measurements and FLEXPART Lagrangian model back-trajectories. In particular, biomass burning plumes in the free troposphere from Africa have been identified. Improvements of the FLEXPART Lagrangian model, undertaken to couple it to the 2.5x2.5 km² AROME weather forecasting model to provide Lagrangian trajectory analysis at mesoscale in complex terrain, will be presented.

We will then describe the scientific objectives of coming field experiments at Reunion Island:

• The OCTAVE program is dedicated to characterizing marine and biogenic terrestrial gas emissions of volatile organic compounds (VOCs) and oxygenated VOCs. Within OCTAVE, an intensive field campaign (Mar-May 2018) will also aim to characterize new particle formation and resolve the potential role of halogen oxides in new particle formation, using different spectrometers at Maido Observatory and in a truck.
• The AEROMARINE program will focus on understanding marine aerosol emissions, their optical properties, and their distribution in the boundary layer and free troposphere, using ground measurements and an instrument payload on board a light plane.
• The ANR CONCIRTO program is dedicated to studying the impact of deep convection and cirrus microphysics on the composition of the upper troposphere and lower stratosphere using balloon measurements and the MIRA cloud RADAR.

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Jerome Brioude received a bachelor degree in physics in 2001 and a PhD in Meteorology in 2006 at Toulouse, France. Then he came to NOAA ESRL CSD in October 2006 as a NRC postdoc to work with Owen Cooper on pollution and cloud cover over the Gulf of Mexico. In October 2007, Jerome became a CIRES research scientist, and worked on cloud-aerosol interactions, halogenated very short lived species, and inverse modeling to improve surface fluxes of chemical reactive species and greenhouse gases. In September 2016, Jerome Brioude became an assistant professor at the University of Reunion Island to teach in the department of physics and work on marine emissions at the LACy laboratory.