Polar Cloud Bacteria

In this research project her team is examining the role that bacteria could play in polar atmospheric cloud formation and precipitation processes (on the general topic of bacteria in the atmosphere see: Biological Ice Nucleators.

As Co-PI with Brian Swanson from the Laucks Foundation she is investigating whether polar bacteria can interact with ice surfaces via ice nucleation processes. It is known that heterotrophic bacteria play a key role in carbon cycling in polar regions, but little is known about how they interact with their geological material, the ice itself, be it sea-ice, lake ice, glacier ice or ice in the atmosphere. The climate of the earth is very sensitive to the microphysical, radiative and chemical properties of glaciated clouds (IPCC, 2001). Accurate climate modeling requires that the entire process from particle formation to cloud drop nucleation be known. Studies of Arctic ice forming nuclei (IFN) have concluded that marine bacteria and other particles of biological origin derived from open leads within the sea-ice cover could be importantfor cloud formation in the Arctic (Bigg and Leck, 2002), but no investigations have been done on the ice-nucleating behavior of marine bacteria temporarily enclosed in sea ice. In Antarctica, devoid of a terrestrial source for IFN, studies also suggest that biological nuclei play a role in the formationof coastal clouds and that the surrounding ocean might be their source (Saxena, 1983). In this project with Brian Swanson, the researchers are investigating a likely origin of these biological nuclei – marine psychrophilic bacteria and viruses using a novel freeze tube technique that studies the freezing of droplets in free-fall.

Data set available from NASA’s Global Change Master Directory

Funding Source: NSF- OPP grant 0338333