Aerosol Properties, Origins, and Impacts within Complex Mountainous Terrain in the Upper Colorado River Basin
ALLISON AIKEN, Abu Sayeed Md Shawon, Katherine Benedict, Leah Gibson, Paul DeMott, Sonia Kreidenweis, James Smith, Jiwen Fan, Jessie Creamean, Russell Perkins, Darielle Dexheimer, Swarup China, Fan Mei, Gregory W. Vandergrift, Zezhen Cheng, Daniel Feldman, Los Alamos National Laboratory
Abstract Number: 457
Working Group: Remote and Regional Atmospheric Aerosol
Abstract
Aerosols are central to understanding surface-atmosphere exchanges and the water cycle within mountainous regions due to aerosol-cloud-precipitation interactions. Since they are distributed vertically within the column, they can impact large-scale circulation, precipitation, and land-atmosphere interactions. For these reasons, it is important to know the physical and optical properties, but also chemical composition to understand their lifecycles and influence within an integrated mountain hydroclimate. We report aerosol properties observed during the U.S. Department of Energy’s Surface Atmosphere Integrated field Laboratory (SAIL) campaign, a 21-month deployment (September 2021 - June 2023) of the Atmospheric Radiation Measurement (ARM) Facility in the Upper Colorado River Basin near Crested Butte, Colorado. The Aerosol Observing System (AOS) collected a comprehensive suite of aerosol measurements on Crested Butte Mountain while the Tethered Balloon System (TBS) collected data vertically within the boundary layer during different seasons. We also deployed specialized instrumentation from LANL to measure bioaerosol and supermicron particles. Based on the chemical composition of aerosols collected at SAIL, we found that most of the aerosols were organic, indicating the importance of local and regional biology and ecosystems for controlling the limited numbers of aerosols in the domain. At the SAIL sites which ranged from 9,500 ft asl to 10,291 ft asl, the average mass concentration of PM10 was <10 ug/m3 with submicron number concentrations <100 #/cc and organics <2 ug/m3 measured at the higher elevation site. Black carbon was <15 ng/m3 indicating little impact from combustion sources and aerosol were mostly scattering with single-scattering albedos (SSA’s) of ~0.9. Transient events that significantly depart from background conditions due to transported biomass burning, urban combustion and dust (during snow-covered periods) increased PM10 aerosol concentrations up to as high as ~200 ug/m3 as occurred in April 2023 and lasted hours to days will also be presented.