As fog gathers around the L’Atalante research vessel, many of us see it as a potential navigation hazard, or a limitation for our wildlife observer on board. However, this blanket of molecules provides an opportunity for some of our scientists to examine interesting properties of the particles in the air, and how they relate to climate and weather.
Aerosols are liquid droplets or solid particles suspended in a gas. These can range from organic matter like pollen to inorganic matter such as salt from the sea. How does this fit into the AZOMP/ADOCCS research mission? Investigating the composition, size, and number of aerosols in the air can lead to a better understanding of how clouds form.
The brightness of clouds is a key factor in how much of the sun’s radiation is reflected rather than absorbed. This reflection process is called the albedo effect and it helps regulate the climate by reflecting energy back out of the atmosphere.
When clouds are forming, aerosols can act as a building block for water droplets to stick to and form into larger particles. An increase in aerosols increases the density of cloud droplets (in other words, how close the particles are to each other). This high-density cloud is often brighter and reflects more radiation from the sun. In contrast, darker clouds are usually made up of a fewer number of large droplets which in turn absorb more radiation.
Ajatshatru Balaji, a graduate student, and Lauren Robinson, a research assistant, are working on board to collect data on aerosols and cloud droplets to better understand this process. They are part of Dr. Rachel Chang’s aerosol and cloud processes lab group at Dalhousie University, investigating aerosols from both land and sea in different areas of the world. The group has also run similar studies examining aerosols and their interaction with water droplets and cloud formation in the Arctic, Grand Banks, and the Yellow Sea.
As part of the Transforming Climate Action research program, Ajatshatru and Lauren are collecting data on aerosols released during phytoplankton blooms, and ultimately areas of high primary productivity in the Labrador Sea, and comparing them to aerosols released in less productive areas. More specifically, their many instruments can measure the composition, size, and abundance of aerosols present.
Aerosols from the ocean are released into the air through sea spray, so rough seas (while unpleasant for us) usually mean more sea-derived aerosols are present in the atmosphere. These aerosols can be composed of organic components directly from phytoplankton and their excretions, or from other organisms feeding on them such as zooplankton. Salt is also released into the air from sea spray and tends to be a larger substrate for cloud droplets to form on. Whether there are more organic particles relative to salts and other aerosols (such as dust from the land) affect how the clouds are formed and their ability to reflect solar radiation. This knowledge will help scientists better understand how our ocean and the organisms within it regulate our climate, while also providing insight into how these processes may be altered with global climate change.
