I am a Senior Research Scientist in Prof. Sonia Kreidenweis's research group, within the Atmospheric Chemistry Program. My research interests at CSU lie in the area of aerosol-cloud interactions, particularly ice phase transitions of atmospheric particles for conditions present in various regions of the troposphere, including layer clouds in winter, cumulus clouds, and cirrus clouds. The goals of my research are to understand the way that the physical, chemical, and biological makeup of certain aerosols of natural or anthropogenic origin determine the formation of ice crystals (precursors of precipitation) in clouds and in turn how clouds impact the distribution and nature of ice nucleating particles in the atmosphere. This information is important to the fundamental issue of how aerosols affect climate indirectly by impacting the radiative properties of clouds, latent heating of the atmosphere, and precipitation. Other awesome members of our ice phase transitions study group at CSU include Dr. Kaitlyn Suski, Dr. Thomas Hill, Dr. Ezra Levin, Dr. Gregory Schill and Ms. Christina McCluskey. Our research approach involves laboratory and field studies using specialized instrumentation, and numerical modeling studies from the process level to the global scale in collaboration with external investigators and the Center for Multiscale Modeling of Atmospheric Processes (CMMAP).

Curriculum Vitae


  • Christina McCluskey sails the Southern Ocean during CAPRICORN.

    Our own Christina McCluskey is collecting the first ever oceanic ice nucleating particle data with the CFDC instrument and daily Ice Spectrometer filters as part of the Clouds, Aerosols, Precipitation, Radiation, and atmospheric Composition Over the southeRn oceaN (CAPRICORN) study, led by researchers from the Australian Bureau of Meteorology and CSIRO. Support for her participation is being funded by the Physical Meteorology Division at NSF. While this is a challenging deployment, we are hopeful that Christina will come home with a unique and powerful data set for quantifying remote marine sources of INPs when placed in the context of a wide range of oceanographic, aerosol, and meteorological data sets that are being collected by investigators from other institutes and agencies. This is the first in a series of studies that will comprise the SOCRATES (Southern Ocean Clouds, Radiation, Aerosol Transport Experimental Study) project expected to continue through 2018. Oh, and the views can sometimes make up for the waves! You can follow the voyage here (http://www.cmar.csiro.au/data/underway/).
  • Center for Aerosol Impacts on Climate and the Environment (CAICE) research underway at CSU.
    As part of the CAICE research team (see Research tab), first experiments were conducted in our laboratory during February 2016 using the CAICE mini-MART (mini-Marine Aerosol Reference Tank) sea spray aerosol (SSA) generation system. In collaboration with CAICE Research Scientist Francesca Malfatti of OGS (Istituto Nazionale di Oceanografia e di Geofisica Sperimentale), Trieste, Italy, we perfromed studies examining ice nucleating particle (INP) emissions in SSA in a controlled and simplified marine microbial system. A working hypothesis is that intense bacterial degradative activities shape the continuum of organic matter in seawater and the sea surface microlayer, thus regulating the production and fate of INP in the SSA. Seawater was collected at the Ellen Browning Scripps Memorial Pier (SIO, UCSD) and shipped to CSU. Within 24 hours, the seawater was filtered onto a 0.6 micron pore-size filter to remove protists and attached bacteria. The water was added to the mini-MART and the free-living bacteria and the viral populations were allowed to acclimate for 24 hours. Then dead algal detritus was added to simulate the demise of a phytoplankton bloom, targeting 2.5 microgram/L Chl a concentrations. Seaspray aerosol was continuously produced by the water mill system of the MiniMART. Aerosol size distribution (APS, SMPS), bioaerosol characterization (WIBS), INP properties (Ice spectrometer and CFDC), bacterial and viral dynamic and bacterial degradative activities were followed (via enzymatic measurements) daily. Full results will be presented at the CAICE annual meeting in early April.
  • Our group hosted two international Ph.D. student visitors in 2015.
    Thea Schiebel, from the AIDA team at Karlsruhe Institute of Technology, visited from July 16 to October 15. Here Thea helps in setting up for FIN03 measurement campaign at Storm Peak Lab in Steamboat Springs, CO on September 11. Yvonne Boose, from ETH Zurich visited during January to April 2015 and participated actively in laboratory and field studies during the ACAPEX/CALWATER 2015 campaigns. Dr. Boose graduated in February 2016. We greatly benefit from the energy and new experiences that such visitors bring to our team.
  • Summer student interns also enliven our laboratory annually. In 2015, we welcomed Katie Rocci as an NSF Center for Multiscale Modeling of Atmospheric Processes (CMMAP) undergraduate summer intern. Katie processed INP samples from last winter's research studies and analyzed these with regard to meteorological and aerosol chemical characteristics for use in a future publication. We love working with summer interns like Katie, and count some of our own (Christina) and many of our department graduate students as former CMMAP interns. We look forward to hosting additional interns in Summer 2016, via CAICE and other fellowship opportunities.
  • Christina McCluskey received an international travel award from the CSU Department of Atmospheric Science's ASCENT (Assisting Students, Cultivating Excellence, Nurturing Talent) program that supportx stays abroad for achieving research objectives. This grant supported her travel costs to attend and collect data on the ice nucleating properties of sea spray particles during an August 2015 measurement campaign at Mace Head, Ireland, at the invitation of Prof. Colin O'Dowd of the National University of Ireland. The Mace Head study is a large campaign organized under the BACCHUS (Impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding) FP7 EU program centered at ETH Zurich, under the leadership of Prof. Ulrike Lohmann. Read about it and see Christina at Mace Head here!
  • The Fifth International Ice Nucleation Workshop (FIN), co-led by Dr. DeMott with Drs. Daniel Cziczo of MIT and Ottmar Möhler of the Karlsruhe Institute of Technology (KIT), has been underway since November 2014. This workshop is the most comprehensive ever held concerning atmospheric ice nucleation studies. Three phases involving participants from all over the world included intercomparison of single particle mass spectrometers for measuring ice nucleating particle composition at the KIT AIDA cloud chamber facility (FIN01: November 2014), intercomparison of ice nucleation measurement methods at AIDA (FIN02: March 2015), and intercomparison of methods for sampling ice nucleating particles from ambient air at Storm Peak Laboratory (FIN03: September 2015). U.S. investigators and activities are supported by NSF funding, and additional support for FIN03 is being provided by DOE-ASR. A workshop on preliminary results of the first two campaigns was held at Colorado State University prior to the FIN03 deployment. Stay tuned for first publications from this important effort.
  • Recent publications: "Microbial Control of Sea Spray Aerosol Composition: A Tale of Two Blooms" a paper of some key results from CAICE wave channel studies last year, led by Xiaofei Wei of UCSD, was published and highlighted in ACS Central Science. Collaborative studies with the Bertram group, titled "The micro-orifice uniform deposit impactor-droplet freezing technique (MOUDI-DFT) for measuring concentrations of ice nucleating particles as a function of size: improvements and initial validation" were published recently in a paper in AMT led by Ryan Mason of U. British Columbia.
  • Paul attended the National Academy of Sciences Sackler Colloquium on Improving Our Fundamental Understanding of the Role of Aerosol-Cloud Interactions in the Climate System. Check out his presentation and others at this meeting on the Sackler YouTube Channel!
  • In an April 2015 ceremony, Christina McCluskey was honored with the Herbert Riehl Memorial Award for the best technical manuscript published by a CSU Atmospheric Science graduate student during the previous 18 months. Christina gave a short presentation on her paper, which summarized her M.S.research on the ice nucleating properties of biomass burning aerosols from prescribed fires and wildfires.
  • Recent ship cruises with collaborating organizations are augmenting our growing collections of new samples of ice nucleating particles over Southern Oceans, the first in nearly 30 years! Tom Hill and CAICE student, Charlotte Beall, arranged for collections of filter samples for offline analyses of ice nucleating particles on two recent cruises in Southern Ocean regions. Collections in early 2015 were organized with Dr. Mike Harvey of New Zealand's National Institute of Water and Atmospheric Research's (NIWA). Student Blake Hornblow (see blog here) performed collections during a 45 day cruise from Wellington to the edge of the Antarctica ice sheet and back on NIWA's RV Tangaroa. During late March 2015, Dr. Melita Keywood (CSIRO) organized collections on a 15 day cruise over the ocean south of Hobart, Tasmania on CSIRO's Marine National Facility ship, the RV Investigator.

Contact info

Paul J. DeMott
Department of Atmospheric Science
1371 Campus Delivery
Colorado State University
Fort Collins, Colorado 80523
email*: Paul.Demott-AT-colostate.edu
office: (970) 491-82577

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