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Under the influence of aerosols
Thematic Project seeks to better understand the influence of atmospheric aerosols by cross-referencing datasets and studying the physical and chemical properties of these particles (photo: Fabio Pozzebom/ABr)
By Alex Sander Alcântara
Agência FAPESP – How is it that an increase in the emission of atmospheric particles (aerosols) can affect the annual rainfall pattern in the southeastern region of Brazil, particularly in the state of São Paulo? How important is the role of aerosols in provoking rain events?
These were among the questions that led a group of researchers at the Universidade Estadual Paulista (UNESP, Paulista State University), in Araraquara, to study particulate emissions and their effect on climate in southeastern Brazil.
In proposing the thematic project "Effects of emissions on alterations in current and future annual rainfall in Brazil’s southeast", which is part of the Programa FAPESP de Pesquisa em Mudanças Climáticas Globais (PFPMCG, FAPESP Program for Research on Global Climate Change), the group led by professor Arnaldo Alves Cardoso of the UNESP Institute of Chemistry in Araraquara seeks to better understand the influence of atmospheric aerosols by cross-referencing datasets and studying the physical and chemical properties of these particles.
Although based at UNESP’s Institute of Chemistry, the project includes collaborating researchers at the Universidade Estadual de Campinas (Unicamp, State University at Campinas) and the Universidade de São Paulo (USP, University of São Paulo), as well as international partners.
Cardoso emphasizes that changes in income-generating activities can alter the properties, amount and type of particles in the atmosphere. "These particles can alter the process of cloud formation and consequently affect rain patterns over a region. They can also affect the number of electrical discharges in the atmosphere. The effect on lightning formation is another focus of our project," he told Agência FAPESP.
Aerosols are small solid or liquid particles dispersed in the atmosphere. "Smoke is composed of visible particles, but many particles are so small they aren’t visible to the naked eye," Cardoso said.
"A lot of particles are created by chemical reactions or condensation in the atmosphere itself. For example, water evaporating from the surface of a lake can condense into small drops, creating a type of atmospheric aerosol," he explained.
Atmospheric particles can be classified as primary (emitted directly as large particles) or secondary (smaller particles, formed in the atmosphere). Human activity, like burning sugarcane fields or construction work, tends to increase the emissions of particles.
"The particles that collectively serve as the nucleus for the formation of a cloud need to have a specific size and concentration, as well as the ability to absorb water. Many particles can only absorb a little water and might not grow large enough to form rain drops," Cardoso said.
Opportunity for a postdoctoral candidate
The abovementioned thematic project has an opening for a postdoctoral researcher in atmospheric sciences to assist in carrying out the research program. Candidates should be able to demonstrate a strong background in atmospheric sciences, and preference will be given to those with experience in related areas.
The successful candidate will receive a postdoctoral monthly stipend equivalent to US$2,590. More information regarding the position is available on the FAPESP – Opportunities page of the FAPESP website: www.oportunidades.fapesp.br/en/97.
According to Cardoso, coordinator of the thematic project, the successful candidate should be prepared to write reports and scientific papers. "We need a researcher who is able to work with chemical data and correlate it with data from satellites and radar," he said.
He points out that not all atmospheric particles are harmful. "In the case of acid rain, particulate matter acts like a sponge and removes some of the acidity from the atmosphere," Cardoso said.
"It doesn’t help to ban sugarcane burning if we don’t know what the effects are, either before or after. An example is what happened in Europe, where a law was passed to reduce particulate emissions and ended up causing an increase in acid rain. The fact that we are trying to understand these processes will allow us to intervene with more certainty," he said.
The thematic project, which began in July, lasts until 2013. For more information, contact Professor Arnaldo Cardoso.
Applicants wishing to apply for this postdoctoral research grant should submit their complete curriculum vitae, three letters of recommendation and a cover letter explaining why the applicant is interested in working on the project. The materials should be sent to the address below and must be received by January 8, 2010.
- Prof. Dr. Arnaldo Alves Cardoso
Departamento de Química Analítica
Instituto de Química – UNESP
Rua Francisco Degni s/n – Caixa Postal 355
14801-970 – Araraquara – SP
Brazil