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7.24.15 Meskhidze

NEW INSTRUMENT FOR MEASURING SIZE-RESOLVED SUBMICRON SEA SPRAY PARTICLE PRODUCTION FROM OCEAN

Nicholas Meskhidze, North Carolina State University
July 24, 2015, 10:30 am, NASA Langley, Bldg 1250, Rm 116

Abstract:
Marine aerosols play an important role in controlling the Earth’s radiation balance, cloud formation and microphysical properties, and the chemistry of the marine atmosphere. Since observations only constrain the net forcing of aerosols (anthropogenic + natural) and the global model-predicted radiative effects are shown to be sensitive to prescribed/diagnosed number-size distribution of background aerosols, an accurate knowledge of size‐ and composition‐dependent production flux of sea spray particles is important for correct assessment of the role of anthropogenic aerosols in climate change. One particular knowledge gap in sea spray particle emissions resides in yet uncharacterized contributions of sea spray to the cloud condensation nuclei (CCN) budget over the marine boundary layer. The chemical composition of 50 to 200 nm sized sea spray particles, most critical to modeling CCN concentration from size distribution data is often simplified as purely organic, purely sea-salt or mixture of both. The lack of accurate information of the size‐dependent production flux of sub-micron sea spray particles prevents the modeling community from resolving discrepancies between model-predicted and measured CCN number concentration in the marine boundary layer.

This presentation will show the first results from a new method that can be used to constrain the source strength of the sea salt bearing particles that are injected into the atmosphere from the bubble bursting. We designed a sea-salt specific relaxed eddy accumulation flux system that is composed of a 3D sonic anemometer, two thermodenuders, three differential mobility analyzers, two condensation particle counters, and a CCN counter. The system is based on the volatility/humidified tandem differential mobility analyzer technique and is therefore designed to measure the size-resolved turbulent fluxes of sub-micron sized sea-salt particles for a wide range of meteorological, hydrological and ocean chemical/biological conditions. The system is designed to operate in both Eddy Covariance (EC) and Relaxed Eddy Accumulation (REA) modes. The first field-testing of the instrument was done at North Carolina State University’s Center for Marine Science Technology (CMAST) in Moorehead City, NC. The measurements were conducted from November 22 to 30, 2014. The instrument was field deployed at the US Army Corps of Engineers Field Research Facility in Duck, NC from April 25 to May 9th, 2015. The method and the setup will be presented along with some results from both studies. The presentation will also show some laboratory results for the anemometer wind corrections using a custom built “ship-simulator” and a motion correction package.

Bio:
Nicholas Meskhidze is an associate professor at North Carolina State University. Meskhidze’s research interests include laboratory and ambient measurements of sea spray aerosol hygroscopicity and cloud condensation nuclei (CCN) properties and application of remotely sensed data (MODIS, MISR, CALIPSO) for exploring potential interactions between marine aerosols, ocean productivity, clouds, and climate. His research group is also working on the development of parameterizations of organic aerosol and trace gas emissions from the oceans required for regional and global climate models.

Born in Tbilisi, Georgia, Meskhidze received his Diploma in Physics from Tbilisi State University. He received his PhD from Georgia Institute of Technology, Atlanta, GA, where for two years he worked as a postdoctoral fellow with Thanos Nenes. Meskhidze also worked as a visiting fellow at NASA Goddard Space Flight Center (GSFC). In 2006 Meskhidze became an Assistant Professor at NC State University Department of Marine Earth and Atmospheric Sciences.

Meskhidze has authored or co-authored 35 articles in peer-reviewed scientific journals. Organized several international workshops and is an editorial board member for Advances in Meteorology, Atmospheric and Climate Sciences, and Journal of Marine Science: Research & Development.

Meskhidze’s Website: http://www4.ncsu.edu/~nmeskhi/Homepage.html

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