AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Cloud Particle Precursors in and around West Coast U.S. Storm Systems
MARKUS PETTERS, Hans Taylor, Nicholas Rothfuss, Paul DeMott, Samuel Atwood, Christina S. McCluskey, Thomas Hill, Sonia Kreidenweis, Kimberly Prather, Andrew Martin, North Carolina State University
Abstract Number: 442 Working Group: Remote and Regional Atmospheric Aerosols
Abstract Extratropical storms approaching the West Coast from the Pacific Ocean are responsible for the majority of the annual precipitation in the west coast states. Aerosol-cloud interactions in those storms are complex. Long-range transport of dust and biological particles aloft can initiate ice in mid-level clouds which in turn can seed lower lying clouds with ice crystals. The low lying clouds are formed on marine aerosols that are embedded within the approaching airmass and may be augmented by local pollution sources. Understanding the spatiotemporal distribution of cloud particle precursor concentrations during landfalling storms is important for understanding the role of aerosols in modulating precipitation amounts. The interagency CalWater-2/ACAPEX campaign took place from Jan-March 2015 and included comprehensive multiplatform characterization of landfalling atmospheric rivers and of cloud-active particles that can influence precipitation. Here we report observations of the aerosol characteristics observed at the Bodega Bay Marine Laboratory research site. These include size- and supersaturation resolved cloud condensation nuclei activity (CCN), ice nucleating particle (INP) concentration measured from aerosol-into-liquid sampling and rainwater collections, as well as fluorescent particles concentration measured with online (WIBS-4A) and offline (fluorescence microscopy) methods. First results show that the hygroscopicity parameter of aerosol at Bodega Bay typically ranged between 0.1 and 0.3 and remained low even for “clean marine” periods when aerosol number, surface area, and volume concentration (D < 0.5 micro-m) dropped below 100 cm-3, 2 micro-m2 cm-2, and 0.2 micro-m3 cm-3, respectively. Total fluorescent particle concentrations at the site ranged between 0.01 and 1 cm-3. This work presents a first analysis toward combining ground-based, ship-, and aircraft-based data to develop a four-dimensional view of cloud particle precursor concentrations for CalWater-2/ACAPEX case studies.