Microorganisms are abundant in the atmosphere and play an important role in controlling cloud development, cloud chemistry and ultimately weather patterns. They do this primarily by producing enzymes that catalyze the formation (nucleation) of ice crystals at significantly warmer temperatures than would normally be required for ice formation (-2 C vs. -36 C). Despite the atmosphere?s fundamental role in their dispersal, the abundance, diversity and flux of microorganisms in the atmosphere remain largely unknown. The potential of ice-nucleating microorganisms to significantly impact meteorology and promote microbial dispersal during precipitation events motivates this research. The RAINS project will sample rain, snow and air samples at ground level, and in the lower atmosphere using remote-controlled aircraft. The project will: (1) characterize microbial taxonomic diversity, including in precipitation that occurred between 1794 AD and present, and which is preserved in glacial ice; (2) determine the genetic diversity of microbial assemblages and of individual ice nucleating bacteria and (3) examine the functional diversity with respect to the role of precipitation and biological ice nucleation on patterns of microbial distribution. The work will also determine which microbes carried to the Earth?s surface via precipitation present possible inoculum sources for diseases that impact humans, domestic animals, and plants.
The RAINS project will increase understanding of biodiversity in the planetary boundary layer of the atmosphere, where important meteorological phenomena such as precipitation occur. The Intergovernmental Panel on Climate Change recommended developing a better understanding of the effect of aerosols and atmospheric ice formation in order to improve climate models and forecast the impact of rising global temperature. The proposed study will increase knowledge on the nature of the most active ice nucleators in the atmosphere. Microbial ice nucleation may also allow microorganisms and certain plant pathogens to efficiently cycle between the atmosphere and surface habitats, and RAINS will contribute to ongoing efforts to assess the movement of ice nucleating microorganisms across geographical scales. Outreach efforts will take these advances into high school and college classrooms in the form of hands-on research experiences for students at both levels and will serve as the basis for high school educators to develop unique classroom activities. In addition, an international network of scientists collecting field data on the relationship between biological ice nucleator abundance, cropping patterns and precipitation in dry land regions will be established. RAINS will sponsor an international conference that brings together 10 young career scientists in the network to highlight the advances of these investigations and identify the outstanding scientific questions.
