Single Particle Characterization for Interpreting Ice Nucleating Particle Measurements in the SAIL Field Study
EMSL Project ID
60299
Abstract
Ice formation in clouds is a process that is still not fully understood, yet critically affects precipitation, cloud lifetime, and the radiation balance. Mixed-phase clouds in the Western U.S. critically determine water resources through precipitation processes triggered by ice nucleating particles (INPs). In fact, the hypothesized insufficient abundance of INPs feeding orographic clouds in winter is the basis for annual cloud seeding in the Colorado Rocky Mountains in support of snowpack enhancement. The abundance and nature of INPs will reflect the influences shaping the larger aerosol population seasonally, which are also not well understood for this region.” The Surface Atmosphere Integrated field Laboratory (SAIL) campaign seeks to establish an unprecedented level of collocated observational detail for a mountainous watershed in terms of precipitation, aerosols, clouds, radiation, and hydrology. Through extending aerosol observations for SAIL, including comprehensive INP measurements processed in our laboratory, and aligning EMSL aerosol and INP composition analyses in this research proposal, we seek to answer SAIL science objectives to establish aerosol regimes, identify processes controlling the life cycle of aerosols in those regimes, and quantify the impacts of aerosols on the atmospheric and surface radiative budget. In particular, studies will aid quantifying the sensitivity of cloud phase and precipitation to the concentrations and various types of INPs. Work in our laboratory using SAIL filter samples will quantify INP concentrations through freezing of suspensions of known volumes of filter-collected particles during their cooling. Through use of thermal and organic digestion treatments on these same suspensions, we will be categorizing INPs as being biological (proteinaceous), other organic, or inorganic. The EMSL analyses requested will utilize samples from the Size and Time-resolved Aerosol Collector (STAC) that is deployed as a guest instrument on ARM’s Aerosol Observing System (AOS) and Tethered Balloon System (TBS) during SAIL. Using EMSL computer-controlled scanning electron microscopy with energy dispersive X-ray spectroscopy (CCSEM-EDX) and Environmental Transmission electron microscopy (ETEM), we will determine size-resolved elemental composition of individual aerosol particles and probe internal heterogeneity of particles for a large number of aligned aerosol and INP sample periods. In addition, we will use EMSL’s custom-built ice nucleation cell, interfaced with an Environmental Scanning Electron Microscope (IN-ESEM platform) which can specifically target INPs for direct comparison to our laboratory data. The chance to align EMSL measurements with SAIL studies presents a unique opportunity to obtain an unprecedented level of detail on characterizing INPs for any region, let alone one where they are so vital to water resources. These analyses representing seasons and covering 1.5 years of SAIL will capture the influences of biological, biomass burning, soil and desert dust, and cloud seeding particle influences as INPs, and serve as the basis for INP parameterizations for use in numerical models, including the DOE E3SM model.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2022-10-01
End Date
N/A
Status
Active
Released Data Link
Team
Principal Investigator
Co-Investigator(s)