What is in the air that we breathe? Why does it matter? Aerosols and their Long Term Impacts
By Ricardo Alfaro
Atmospheric aerosols are tiny particles that float around in the Earth’s atmosphere. They come in a variety of shapes and sizes and are produced in nature, as well as a result of human activity. Some natural sources of aerosol come in the form of dust blown by wind, salt that has evaporated from our oceans, and ash from volcanoes erupting around the globe. Man-made aerosols have different sources ranging from the burning of fossil fuels to smoke from forest fires. Although they are small in size, they can prevent solar light from reaching the surface of the Earth, as well as cool down the surface (known among scientists as “radiative cooling”). For example, a thick smoke plume from Canadian fires lingered over Grand Forks on June 29, 2015 (as pictured below), causing a significant reduction in regional surface temperature.
Additionally, aerosols can impact human health by worsening the quality of the air that we breathe, causing so–called particulate matter pollution. Among scientists, this is sometimes known as “PM2.5 pollution,” where “PM” stands for “particulate matter,” and “2.5” refers to particulates up to two point five micrometers in diameter (one micrometer or micron is one millionth of a meter). Using remote sensing methods, such as instruments mounted on satellites in orbit over Earth, I have performed a long-term analysis of aerosol concentration, as well as the resulting radiative effects on both global scales and regional ones, like the Northern Great Plains. This analysis allows us to gain an insight into regional and global variations of particulate matter pollution, as well as their impacts on solar and terrestrial radiation. Initial studies have been limited to over-ocean scenes; however, the analysis is currently being expanded to include over-land observations including the Northern Great Plains region in the United States.
Read some of Ricardo’s published research here: Alfaro-Contreras, R., Zhang, J., Campbell, J. R. and Reid, J. S. 2015: Investigating the frequency and trends in global above-cloud aerosol characteristics with CALIOP and OMI, Atmos. Chem. Phys. Discuss., 15, 4173-4217. doi: 10.5194/acpd-15-4173-2015.