AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Aerosol Formation and Growth Associated with Hurricane Intensification: Observations from Hurricanes Edouard and Cristobal in 2014
LUKE ZIEMBA, Michael Shook, Andreas Beyersdorf, Richard Moore, Kenneth Thornhill, Edward Winstead, Bruce Anderson, NASA
Abstract Number: 617 Working Group: Aerosols, Clouds, and Climate
Abstract Particles are integral to convective storm dynamics by serving as cloud condensation nuclei (CCN) and ice nuclei. Aerosol effects are especially uncertain for hurricane formation, intensification, and dissipation, where the role of aerosols is unclear and difficult to decouple from overlying meteorological factors. For example, the prevalence of dry air associated with the Saharan Air Layer (SAL) makes understanding the role of transported dust on Atlantic hurricanes difficult to untangle. While much attention has focused on interactions between SAL dust and hurricanes, storms with well-formed eyes may present conditions conducive to new particle formation, i.e., low surface area of pre-existing aerosols to promote nucleation and enough time isolated from wet scavenging for condensation or coagulation growth.
Aerosol number concentration (BMI mixing condensation particle counter, model 1720) and size distribution (DMT Ultra-High Sensitivity Aerosol Spectrometer) observations were made from a NOAA WP-3D hurricane hunter aircraft during the 2014 hurricane season. Two storms were sampled. Hurricane Cristobal was sampled over a three day period from August 24-26 during transitions from tropical depression to Category 1, never forming an organized eye before weakening off the Atlantic coast. Hurricane Edouard did not threaten the continental coast, but rapidly intensified East of Bermuda forming a well-defined eye and reaching Category 3 strength on September 16. Here, we contrast aerosol observations associated with these storms, where high particle concentrations (greater than 5x10$^3 cm$^(-3)) were observed only during penetrations of Edouard’s eye. A large fraction of the size distribution was above 60 nm diameter, particles that were likely effective CCN. Concentrations inside the hurricane eye were always greater than at the storm periphery, suggesting local formation. The highest concentrations were observed during Edouard rapid intensification. Potential ramifications on storm dynamics of new particle formation inside the eyes of hurricanes are discussed.