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10.26.17 DeMott

Topic: Ice Nucleating Particle Measurements for Constraining Primary Ice Nucleation in Mixed-Phase Clouds

Speaker: Dr. Paul DeMott, Dept. of Atmospheric Science, Colorado State University

Date: Thursday, October 26, 2017

Time: 10:30-11:30 a.m.

Location: NASA/LaRC, Bldg 1250, Room 116

Abstract: Aerosol-cloud interactions involving the ice phase remain as poorly explored phenomena. Primary ice nucleation on ice nucleating particles (INPs) serves as the trigger for controlling the ice phase composition and precipitation from ubiquitous mixed-phase clouds. Understanding the sources and emissions of INPs constitutes the initial step needed for parameterizing their action in numerical models, thereby helping to constrain their role in impacting cloud radiative properties and the hydrological cycle. There is circumstantial evidence that the abundance of INPs can play a role in impacting cloud radiative properties regionally and globally, especially at higher latitudes and over oceans. In this presentation, motivations and current status of capabilities for measuring INPs will first be reviewed, and then studies will be introduced regarding the distinct biologically-mediated, organic INP populations that are emitted from land (in addition to mineral sources of INPs) and ocean surfaces. Finally, the implications of these results for the relative importance of these sources, where aerosol impacts on ice phase clouds should be most easily demonstrated, and the need for representation of INP emissions in global models will be discussed.

**Note: This seminar is sponsored by the NIA Internal Research and Development (IRAD) program.  NIA Vice President of Research, Dr. David Throckmorton, will briefly introduce the program at the beginning. Those who are interested in joining the lunch group (Thai Erawan) or would like to meet with the speaker individually during the day may contact Hongyu Liu (1250/209, or Patrick Taylor (1250/179,**

Bio: Dr. Paul DeMott is a Senior Research Scientist/Scholar in the Department of Atmospheric Science at Colorado State University (CSU), where he has held research positions prior to and after receiving his PhD in 1990. At Colorado State he served as director for the former Cloud Simulation and Aerosol Laboratory, and helped develop the first airborne continuous flow diffusion chamber for measurements of ice nucleating particles. His research group conducts laboratory studies and in situ measurements on cloud-active aerosol properties, and development of parameterizations for cloud and climate models, His recent research has emphasized assessing measurement capabilities of present-generation ice nucleation instruments, and studies of organic ice nucleating particles from land and ocean sources. Paul received the CSU Distinguished Service award in 2003, and the CSU Distinguished Alumnus Award in Atmospheric Science in 2009. (URL:



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