Overview

Our research focuses on aerosols in the stratosphere and their role in the Earth's climate. We study aerosols from natural sources, such as volcanic eruptions and forest fires, and anthropogenic sources, such as fossil fuel burning and geoengineering. Most of our research is carried out with climate model simulations, but we also use satellite and in-situ measurements from aircraft- and ground-based instruments.

If you are interested in working with us, check out the Opportunities page and contact Prof. Aquila. If you already have a project in mind, please send me an email and we can discuss new opportunities and collaborations.

Eruption of Mt. Sarychev on June 12, 2009. ISS Crew Earth Observations Experiment and Image Science & Analysis Laboratory, Johnson Space Center via NASA Earth Observatory.

Volcanic eruptions

Volcanic eruptions suddenly change the composition of the atmosphere by emitting gases, ash, and sulfate particles. By changing the radiative budget and chemistry of the atmosphere, these volcanic aerosols cool the Earth's surface and warm the stratosphere, alter winds and precipitation patterns, and destroy stratospheric ozone, among other effects. Our research to date has focused on the impacts of the 1991 eruption of Mount Pinatubo on stratospheric winds and ozone concentrations, as well as on the role of volcanic eruptions in the satellite stratospheric temperature record. Currently, we are working on understanding the impact of eruptions on seasonal forecasts and on the composition of the lower stratosphere.

We have recently been awarded fundings from NASA to explore the role of volcanic ash in the development, transport, and radiative impact of volcanic plumes. Check out the Opportunities page if you are interested in working on this project.

Geoengineering

Geoengineering is the deliberate intervention on the climate system to offset the warming due to increasing greenhouse gases. Two families of geoengineering technologies have been proposed: one (carbon dioxide removal) aims at decreasing the concentrations of carbon dioxide in the atmosphere, the other (radiation management) at decreasing the amount of radiation in the Earth system. One of the proposed radiation management technologies would decrease the solar radiation reaching the surface of the Earth by injecting aerosols in the stratosphere, to mimic volcanic eruptions. Our research focuses on the impact of such intervention on the stratospheric composition and dynamics. Geoengineering via stratospheric aerosol injection has the potential of depleting stratospheric ozone and delaying the closing of the ozone hole, as well as introduce changes in stratospheric winds.

Image by Climate Central.

PyroCb in Colorado. Luis Rosa, NWS San Juan PR.

Stratospheric aerosols

Volcanic eruptions and geoengineering are not the only sources of aerosols in the stratosphere. In specific meteorological conditions, forest fires can generate pyrocumulonimbus clouds (pyroCb), thunderstorms that inject smoke in the lower stratosphere. Surface air pollution can be transported to the lower stratosphere through convective systems like the Asian summer monsoon. Additionally, meteoritic dust settles in the stratosphere from above. Generally, the largest perturbations of the stratospheric aerosol layer are associated with volcanic eruptions, but studies have shown how these other sources of stratospheric aerosols are more important than previously thought. Our lab is working on quantifying the role of these aerosol sources in the stratosphere aerosol budget.

Urban air quality

Fine particulate matter (or PM) is one of the main air pollutants. Exposure to high PM concentrations can cause serious health problems, especially in vulnerable populations. Our lab has been working with communities in Washington, DC to measure air concentrations of PM using low-cost air quality monitors hosted by local residents. Thanks to their low cost and ease of use, low-cost air quality monitors allow residents to gather real-time information on their exposure to air pollutants.

Low visibility due to air pollution in New York City in 1973. Source: EPA Documerica "Then and Now Challenge"