Every winter, those residing within the eastern half of the U.S. are slammed by powerful storms that pound cities with snow – costing millions of dollars in damage, halting travel, and impacting businesses and schools. Yet, like a thumbprint, each of these winter storms are unique and they can possess a range of tracks, structures, and intensities. This research project aims to provide a greater understanding of the development of such storms and the causes of precipitation variability within them by focusing on a single storm that hit the Midwest on 17 February 2022 as a part of a research flight conducted during the Investigation of Microphysics and Precipitation for Atlantic Coast-Threatening Snowstorms (IMPACTS). I analyzed data from multiple sources to explore the large scale environmental conditions and the fine scale precipitation structure. The environmental conditions included a strong thermal contrast, or a frontal boundary, that provided the lift needed for precipitation as well as sub-freezing surface temperatures that allowed for precipitation to fall as snow. Analysis of the vertical cloud and precipitation structure from radar data collected during the flight revealed regions of higher reflectivity where snow was heavier than in other portions of the storm. Microphysical properties, such as particle sizes, shapes, and ice water content were different within the region of high reflectivity than outside it. Additionally, the strengthening front at the 700-hPa pressure level coincided with the localized region of enhanced reflectivity observed by the ground-based and airborne radars. The high-resolution radar and microphysics data collected by the IMPACTS airborne instruments are used to help identify precipitation-defining processes within these storms, and ultimately will increase the accuracy of snow prediction and remote sensing of snowfall from space-borne instruments.

Tornadoes are rare events in the Pacific Northwest and are extremely difficult to predict along the coast, causing much surprise when they do form. After witnessing the destruction and rebuilding of a Port Orchard neighborhood that was ravaged by a F2 tornado in December 2018, I was inspired to explore these uncommon occurrences. For this project, I am investigating the near storm environments of tornadic systems that are generated from cold air outbreaks during the winter months along the coastal Pacific Northwest. This is done by analyzing data from massive tornado datasets, METAR (Aviation Routine Air Report) observations of convective precipitation such as graupel, and piecing together upper air reanalysis data to compare them to weather indexes that have been defined to determine atmospheric instability and can be used to predict extreme weather. The goal is to find patterns that are associated with these tornadic events to create more accurate forecasts and to paint a detailed picture of tornado climatology in the Pacific Northwest. My hope for this project is to shed light onto the factors that are at play for tornadoes, hail, and other severe weather that could potentially save lives.

Tropospheric reactive halogens are a sink for ozone and influence the oxidizing capacity of the troposphere. Daily measurements of chloride enrichment, bromide enrichment, and iodine in sub- and super-micron aerosol were collected in June 2022 and January-February 2023 in Bermuda during the Bermuda boundary Layer Experiment on the Atmospheric Chemistry of Halogens (BLEACH) campaign. Gas-phase halogen radicals originate from heterogeneous reactions (chemical reactions involving more than one phase of matter) on the surface of halide-containing aerosol. These reactions lead to enrichment or depletion of aerosol halides (e.g., particle phase chloride, bromide, or iodide) relative to their ratios with sodium in sea water. We compare these measurements with simultaneous observations of ozone and gas-phase halogen concentrations in order to understand the relationship between aerosol and gas-phase halogens and their impact on tropospheric ozone abundance. Observations from these campaigns will aid in improving atmospheric model outputs and environmental policy. I extracted the ions from more than 60 quartz air-filter samples and aided in method development with Ion Chromatography (IC). Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was primarily used for iodine measurements. Data analysis and lab work is still ongoing, therefore only preliminary observations are available. We’ve observed that sodium, iodine, chloride, and bromide agree well with previous observations at Tudor Hill (Arimoto et al., 1995; Sander et al., 2013). Higher depletions of chlorine excess and bromine excess and higher iodine and non-sea salt sulfate concentrations are observed during the first half of the summer campaign.