Aerosol and Cloud-Nucleating Particle Observations during an Atmospheric River Event

Thursday, 17 December 2015: 16:45
3010 (Moscone West)
Paul J DeMott1, Christina S. McCluskey1, Markus Petters2, Kaitlyn J Suski3, Ezra JT Levin3, Thomas Christopher James Hill3, Sam A Atwood4, Gregory P Schill3, Katherine Rocci5, Yvonne Boose6, Andrew Martin7, Gavin Cornwell8, Hashim Al-Mashat8, Kathryn Moore8, Kimberly A Prather8, Nicholas Rothfuss2, Hans Taylor2, L. Ruby Leung9, Jason M Tomlinson9, Fan Mei10, John M Hubbe9, Daniel Rosenfeld11, J. Ryan Spackman12, Chris W Fairall13, Jessie Creamean14, Allen B White13 and Sonia M Kreidenweis1, (1)Colorado State University, Fort Collins, CO, United States, (2)North Carolina State University at Raleigh, Raleigh, NC, United States, (3)Colorado State University, Department of Atmospheric Science, Fort Collins, CO, United States, (4)Colorado State University, Atmospheric Science, Fort Collins, CO, United States, (5)University of New Hampshire Main Campus, Durham, NH, United States, (6)ETH Swiss Federal Institute of Technology Zurich, Institute for Atmospheric and Climate Science, Zurich, Switzerland, (7)Scripps Institution of Oceanography, La Jolla, CA, United States, (8)University of California San Diego, La Jolla, CA, United States, (9)Pacific Northwest National Laboratory, Richland, WA, United States, (10)Joint Global Change Research Institute, College Park, MD, United States, (11)Hebrew University of Jerusalem, Jerusalem, Israel, (12)Science and Technology Corporation, Boulder, CO, United States, (13)NOAA Boulder, Boulder, CO, United States, (14)University of California, SD, Boulder, CO, United States
The multi-agency CalWater 2015 project occurred over North Central CA and the Eastern Pacific during January to March 2015 (Spackman et al., this session). The goals of the campaign were to document the structure of atmospheric rivers (ARs) that deliver much of the water vapor associated with major winter storms along the U.S. West Coast and to investigate the modulating effect of aerosols on precipitation. Aerosol sources that may influence orographic cloud properties for air lifted over the mountains in California in winter include pollution, biomass burning, soil dusts and marine aerosols, but their roles will also be influenced by transport, vertical stratification, and scavenging processes. We present results from a comprehensive study of aerosol distributions, compositions, and cloud nucleating properties during an intense winter storm during February 2015, including data from an NSF-supported measurement site at Bodega Bay, from the DOE-ARM Cloud Aerosol Precipitation Experiment that included sampling on the NOAA RV Ron Brown offshore and the G-1 aircraft over ocean and land, and with context provided by other NOAA aircraft and remote sensing facilities. With a special focus on the coastal site, we discuss changes in aerosol distributions, aerosol hygroscopicity, and number concentrations of fluorescent particles, cloud condensation nuclei (CCN), and ice nucleating particles (INPs) during the AR event. We compare with periods preceding and following the event. For example, total aerosol number and surface area concentrations at below 0.5 μm diameter decreased from typical values of a few thousand cm-3 and 100 μm2 cm-3, respectively, to a few hundred cm-3 and 10 μm2cm-3 at Bodega Bay during the AR event. CCN concentrations were similarly lower, but hygroscopicity parameter (kappa) increased from typical values of 0.2 to values > 0.5 during the AR.INP and fluorescent particle number concentrations were generally lower during the AR event than at any other times.