The vitality of the rainforests to producing oxygen, their tremendous biodiversity and their ability to store carbon are widely discussed topics that leave little doubt about the importance of rainforests in the Earth’s environment. Despite the plethora of information about these vital biomes, small discoveries can still provide new insights and clarify pre-existing information. Recently, university researchers have applied their unique findings from the rainforest into groundbreaking atmospheric research. Markus Petters was not an expert of rainforests when he traveled to the Brazilian Amazon two years ago to conduct field research in the area of atmospheric sciences. As part of a multinational research team, Petters, assistant professor of marine, earth and atmospheric sciences, set out to study the effects of aerosol particles to the formation of clouds. The Amazon rainforest offered a “pristine environment” to study the effects of cloud condensing nuclei (CCN) on the formation of clouds and its effect on precipitation.
Aerosols in this sense do not refer to CFCs or the propellant gases of spray cans, according to Katie Costa, a second year masters student in marine, earth and atmospheric sciences.
“So basically, aerosols are like dust particles that serve as something that water vapor can condense onto which will form clouds,” Costa said. “In this sense, we refer to these aerosols as CCN.”
Nearly any small particle suspended in the atmosphere can act as CCN, including pollen, dust, sea spray, and pollution released into the air, according to Petters.
“We went to Brazil to find a place unaffected by anthropogenic (human influenced) pollution, like car exhaust or industrial pollution from smoke stacks, such as sulfur emission, because all of these particles have an influence,” Petters said. This research in the Amazon serves as a control variable from which further studies can compare findings.
“You can get the cumulative effect if you do this research in Raleigh” Petter said.
Petters and the team of universities, including Harvard, Colorado University, and various European science institutes, isolated themselves in Manaus, Brazil to avoid any type of contamination to their research.
“We were 1600 kilometers (1000 miles) inland from the ocean, so there was no major CCN source (from sea spray or dust) there. The interesting thing is that the forests themselves maintain the particle budget, or in other terms, their source of CCN.”
As a result of transpiration and various metabolic processes, trees release small aromatic molecules called terpenes into the atmosphere. These “essential oils” can collect and react with water vapor high in the atmosphere.
“Famous terpenes are like alpha pinene from which come the pine smell or limamene for the lemon scent,” Petters said. “They will end up in the atmosphere and react with things like ozone and will become chemically modified and less radical so they do not want to be in the gas phase anymore. This results in a process similar to cloud formation.”
The researchers collected these particles from an observation tower and extracted the aerosols and shipped them back to labs in the U.S. for complete analysis.
Interestingly, due to the large turnover of water vapor and CCN, rainforests act as their own cloud factories, according to Petters. From a microclimate standpoint, the Amazon can sustain itself. However, with each rainfall, the atmosphere clears itself of CCN by 80%, so the rate at which the Amazon flora can put out organic CCN is impressive. Acid rain is an example in which anthropogenic CCN, sulfate emissions in this instance, are cleansed out of the air.
Petters said CCN it is essential to cloud formation in all environments.
“If there were no CCN at all, there would be no clouds,” Petters said. “What you would need to do is create a super saturated water vapor at about 400% before you could get condensation, and this isn’t an option in the atmosphere. However, it doesn’t matter how much CCN you have if there’s no water vapor, but that wasn’t a problem in the Amazon.”
Although the report on CCN research that Petters published in a recent edition of the academic journal Science has been reviewed well, he does not see himself going back to Brazil soon.
“If you’re the outdoorsy type, it was a great place to be,” Petters said. “If you don’t like camping, it wouldn’t be so fun. We were about a two-hour drive on sometimes-impassible roads away from the city. We lived in the forest in a place that was more than a shed, but not exactly a house.”
Petters has maintained his focus on the effects of aerosol particles in the atmosphere since his arrival to the University just over a year ago.
“The university has been very supportive and they’ve given me excellent facilities so I can do what I need to do. It’s a very energetic place with lots of students and great resources.”
Unlike some professors involved in research on campus, Petters has been very involved in the classroom.
“He’s a big believer in that if you show up to class you will succeed,” Sarah Ray, a senior in meteorology, said. “He makes sure to maintain an interesting class as well keep students engaged about the subject material, so that we can do well.”
