03/15/2017
Dust and Organic Sea Spray Contribute to Cloud Freezing
Sea spray is more important to initiate freezing water droplets in clouds than dust on most days in Southern hemisphere mid- and high-latitudes and many days in the Arctic.
The Science
A new study shows how dust from deserts and organic sea spray from tiny organisms in the ocean both play a role in freezing water droplets in clouds.
The Impact
This study shows that for global atmospheric models to adequately simulate the concentrations of particles that trigger freezing of cloud droplets, they must include both desert dust, which has long been recognized as a source of freezing particles, as well as organic matter in sea spray, the importance of which has only recently been recognized.
Summary
While desert dust has long been recognized as an important source of freezing nuclei in the atmosphere, it has only recently been widely recognized that organic matter in sea spray may be another important player, especially over remote oceans. This research, by a team of researchers including a scientist at the Department of Energy’s Pacific Northwest National Laboratory, improves on earlier work by comparing simulated concentrations of freezing nuclei with a larger database of observations than was previously available, and by considering the implications of fluctuations in particle concentrations over time, as dust plumes come and go, for the importance of the two aerosol types.
Funding
This study was funded by the European Union’s Seventh Framework Programme, the European Research Council and the National Environmental Research Council. Susannah Burrows was supported as part of the Accelerated Climate Modeling for Energy (ACME) project, funded by the U.S. Department of Energy, Office of Science Biological and Environmental Research in the Earth System Modeling Program. The global model simulations were performed on the ARCHER UK National Supercomputing Service.
References
J. Vergara-Temprado, B. J. Murray, T. W. Wilson, D. O’Sullivan, J. Browse, K. J. Pringle, K. Ardon-Dryer, A. K. Bertram, S. M. Burrows, D. Ceburnis, P. J. DeMott, R. H. Mason, C. D. O’Dowd, M. Rinaldi, and K. S. Carslaw. “Contribution of Feldspar and Marine Organic Aerosols to Global Ice Nucleating Particle Concentrations.” Atmospheric Chemistry and Physics 17: 3637-3658 (2017). [DOI: 10.5194/acp-17-3637-2017].