Authors

Emily Bolger

Document Type

Internship Report

Publication Date

Fall 2018

Abstract

Satellite-based measurements of aerosols provide insight into relative aerosol concentrations and transport, but are not sufficient in creating an adequate information base for climate models to depend on. Future measurements and process-level studies are necessary to reduce the uncertainties in both the direct forcing of aerosols, the ability of aerosols to seed cloud droplets and ice crystals, and the role of aerosols on ecosystem health. African dust transport is thought to increase the primary productivity in the Amazon rain forest, and the Bodélé Depression in Chad has been identified as the single biggest source of this dust. Filters from the German sampling sight, ATTO (Amazon Tall Tower Observatory), were collected in order to identify diatoms and minerals characteristic of African dust, specifically those characteristic of the Bodélé Depression. The diatoms found in the ATTO samples were almost all fragments of crushed cells of fossilized fresh water planktonic diatom species characteristically found from the Bodélé Depression. Using the HYSPLIT model, the air mass back trajectory of the dust transport for the last week of February 2016 shows that air masses traversed Bodélé before arriving in Cayenne and ATTO highlighting the importance of Bodélé transport on the Amazon Basin. In addition to dust, sea-spray is another the major sources of atmospheric particles and contains large amounts of organic materials that are ejected into the atmosphere through breaking waves. This organic material is associated with phytoplankton cell exudates and has been observed to have a high ice-nucleating ability in micro layer samples. I analyzed seawater samples from INARCO I cruise using SEM coupled with Energy Dispersive X-Ray analysis (EDS) techniques to determine each aerosol’s mixing state, and biological and elemental composition. The initial analysis of the components with the INARCO seawater samples showed high numbers of pennate and centric diatoms. For the harmful algal bloom (HAB) site, the sample filter contained far more diatoms than any of the previous sampling sites and also showed efficient INP (Ice Nucleating Particle) results. This could suggest that high rates of biological activity lead to more efficient INP. After further characterization, more conclusions can be drawn on the transport of African dust into the Amazon and the ice nucleating characteristics of the INRACO I and II samples to understand the air-sea-ice interactions in the Arctic.

Comments

Department: ATM

MPS Track: WCS

Location: Cooperative Institute for Marine and Atmospheric Sciences

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