Research - Current and Recent Field and Laboratory Research
The Center for Aerosol Impacts on Climate and the Environment (CAICE) (NSF-Chem)
(CAICE), based from the University of California - San Diego and Scripps Institution, is a Center for Chemical Innovation that is presently focused on understanding the chemistry and climate impacts of sea spray aerosols. Particles are produced by wave-breaking in a large laboratory wave channel and scaled systems for realistically reproducing particles from bubble bursting of seawater. Dr. DeMott is a Senior Personnel member of CAICE, Dr. Hill is a Research Scientist member, and Christina McCluskey is a Ph.D. student with the center.
Laboratory and Surface-based Studies of Atmospherically-relevant Ice Nucleating Particle Sources, Concentrations and Compositions (NSF-AGS)
This study, funded by NSF grant AGS-1358495, has primary objectives to elucidate the nature of particles produced from various types of INP-emitting soils/Ecoregions, to better constrain the level of emissions and presence of ice nucleating bacteria, fungi and other biological INP to the atmosphere, and to understand the contributions of organic and inorganic ice nucleating particles emitted from plants and soils in general. Existing and new techniques are being applied for identifying biological/organic INP including advanced DNA analyses, and use of online aerosol mass spectrometric methods. The product of this research will be quantitative descriptions for use in numerically modeling the atmospheric distribution of INP sources from land, and their impacts on clouds in a changing climate.
CalWater1, CalWater2, ACAPEX
CalWater is a multi-year study, including ground, ship, and aircraft campaign intensives, with a focus on two key phenomena that play key roles in the variability of the water supply and the incidence of extreme precipitation events along the West Coast of the United States: Atmospheric Rivers (ARs) that deliver much of the water vapor associated with major storms along the U.S. West Coast, and the modulating effects of aerosols (local, pollution, marine, and long range transported dust and biological particles) on western U.S. precipitation. The project has been supported at various stages by the California Energy Commission, the National Oceanic and Atmospheric Administration, the Department of Energy, the National Science Foundation, and the National Aeronautics and Space Administration. Our group's first participation in 2011 was to use ouf continuous flow diffusion chamber (CFDC) to measure ice nucleating particles from ambient (outside of clouds) and counterflow virtual impactor (within clouds) inlets onboard the DOE-ARM Aerial Facilities G-1 aircraft, based from McClellan Airfield in Sacramento, CA . Focus cloud systems were orographic clouds over the Sierra Nevada mountain range east of Sacramento, and cloud systems over the ocean and Coastal Range of California during February and March 2011. Ground-based observations in collaboration with the Prather Group at the University of California - San Diego followed in 2014 at the Bodega Bay Marine Laboratory. CalWater2 and the DOE-funded ACAPEX programs followed as a major field study in January through March 2015. CSU's effort included CFDC instruments on the G-1 and at Bodega Bay, filter sampling for INP post-processing with the Ice Spectrometer on the G-1, at Bodega Bay, and on the NOAA RV Ronald H. Brown ship. The CSU mobile laboratory (ADD) also operated at Bodega Bay in collaboration with the Prather group and the Petters Group from North Carolina State University to collect a large suite of measurements on aerosol physical, chemical, and cloud activation properties. Quicklook data are available via the "Atmospheric River Portal" operated by our colleagues at the Center for Western Weather and Water Extremes.
Ice in Clouds Experiment - Tropical (ICE-T) (NSF AGS-1036028)
We measured IN concentrations using the aircraft version of the CFDC over the Carribean Sea in the vicinity of St. Croix in July 2011 on the NSF/NCAR C-130 Hercules research aircraft. The campaign was interested in ice processes in tropical cumulus clouds, which are poorly constrained and understood. This campaign followed from the ICE-L campaign that previously focused on ice initiation in stable orographic wave clouds (Eidhammer et al. 2010; Field et al. 2012 Field et al. 2012). We measured ambient IN concentrations in the marine boundary layer, flying as low as 100 feet over the sea at times, and also measured IN in cloud residuals by sampling from a counterflow virtual impactor. A large range of trace gas, aerosol and cloud physics measurements were performed on the C-130 as well as the SPEC Inc. Learjet, which also participated. More information about the ICE-T project is available here.
Studies of Ice Nuclei from Biomass Burning (NOAA NA10OAR4310103)
We are conducting a variety of measurements of biomass combustion, in prescribed burns and Western wildfires. These studies augment previous research in the laboratory. Our goal is to quantify and identify IN emissions from fires, which may have larger impacts on climate and precipitation. A first publication of research results is here. In Spring 2011, we took the CFDC instrument to Georgia to measure IN emissions from prescribed fires at the Jones Ecological Research Center. The fires are used to help maintain the lodgepole pine ecosystem that once spread along the entire SE US continental plain. Fires were a natural part of the ecosystem, but supression now means they rarely occur naturally. Policy makers in the southeast have to balance the needs to maintain both healthy forests and air quality. Recently, massive wildfires in Colorado have reached to within 2 miles of our laboratory and we have been sampling the smokes that occasionally blanket Fort Collins.
Quantifying IN Sources from Black Carbon (NASA NNX12AH17G) - FLAME-4 (Fire Lab at Missoula Experiment 4)
We are just beginning studies to obtain data to clarify the role of BC in ice formation, and in aerosol-cold cloud interaction studies using satellite observations. We will use a combination of controlled laboratory biomass combustion studies of plant species from regions of global importance and atmospheric measurements from fixed sites to measure the proportional contributions of BC versus other aerosol types toward atmospheric IN populations and examine the dependence on sources and physical/chemical properties. The primary laboratory campaign will be coordinated within the FLAME-4 study in October to November 2012 in Missoula, MT. That study with collaborators from the University of Montana, Carnegie Mellon University and others, and will include smog chamber studies of smoke processing impacts. Key in our approach is to utilize novel combinations of existing instruments (SP-2, HTDMA, CFDC) to measure the concentrations of freezing nuclei before and after selective removal of BC particles, and to define the association of IN with particle hygroscopicity, composition, BC content, and atmospheric processing (CMU smog chambers). These measurements will provide the basis for revising (existing) and developing new numerical descriptions of BC and other biomass burning aerosol activation properties as ice nuclei for use in numerical simulations to predict the cold-cloud impacts of biomass burning emissions and ambient BC. Parameterizations will be sought that can use remotely sensed data from present and future satellite missions, such as global fire activity, aerosol optical depth, retrieved aerosol microphysical and optical properties, and carbon monoxide, to observationally constrain IN number concentrations.
BEACHON-RomBAS (NSF) Studies of Cloud Active Aerosols Over Forests
The BEACHON-RomBAS (Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics & Nitrogen - Rocky Mountain Biogenic Aerosol Study) field intensive was a multi-investigator study conducted at the Manitou Forest Experiment Station near Woodland Park, CO, during July and August 2011 (website). The study helped fulfill multiple objectives, all of which are aimed at the goal of assessing the influence of ecosystem processes, and their responses to climate, on the number and composition of climatically-relevant biogenic aerosols and their potential to function as CCN and IN, and to modify precipitation. Our activities under NSF ATM-0919042 focused on collecting annual cycle data on CCN activity/hygroscopicity of biogenic particles (Levin et al. 2012) and speciation of primary biological particles, and on measuring IN activity and its association with primary biological particles and other environmental influences during the field study intensive. IN measurements included application of pre-concentration of aerosols and collection of IN for both biological and chemical speciation, all for the first time. Multiple publications are in preparation.