The Atmospheric Science and Chemistry mEasurement NeTwork (ASCENT) is a new comprehensive, high-time-resolution, long-term measurement network in the U.S. for the characterization of aerosol chemical composition and physical properties. ASCENT is funded through the NSF Mid-Scale Research Infrastructure program.

Climate change and air pollution are two major environmental issues confronting the world today, and they are intricately related. Aerosols (also referred to as particulate matter, PM) play a critical role in both. Aerosols impact climate by changing the Earth’s energy balance via direct absorption or scattering of solar radiation and altering the albedo, formation of clouds, and precipitation. Exposure to fine aerosols (particles with a diameter smaller than 2.5 µm, PM_2.5) results in millions of premature deaths worldwide each year. A more complete understanding of the sources, chemistry, dynamics, and chemical and physical properties of aerosols is critical to accurately assess and predict their impacts on climate, human health, visibility, and ecosystems in a changing environment.

Leveraging existing networks, a total of 12 sites will be established across the country, including rural/remote/background, urban, and tribal sites. Each site will be equipped with a suite of advanced aerosol instrumentation for real-time measurements of fine aerosol chemical composition and properties: Aerosol Chemical Speciation Monitor (ACSM, non-refractory aerosols), Xact (trace metals), Aethalometer (black/brown carbon), and Scanning Mobility Particle Sizer (SMPS, aerosol number size distribution and concentration). In addition, value-added products will be developed, including parameterizations of FT-IR and ACSM data to increase the chemical resolution of organic aerosols from the ACSM, as well as aerosol source apportionment analyses.

A comprehensive data infrastructure will also be developed for automated data quality assurance/control, upload/download, discovery/visualization, and long-term data preservation, providing open and free access to ASCENT database.

ASCENT will enable a wide range of new and exciting research capabilities in atmospheric science, climate, and air quality, and will advance our understanding of aerosol sources and characteristics on spatiotemporal scales not previously possible. ASCENT will also provide essential information to fully utilize new observations from upcoming satellite-based instruments. With the development of the mid-scale infrastructure, ASCENT provides the fundamental knowledge critical for informing science-based policy decisions on climate and environmental change, including air quality, and minimizing inequalities in air pollution exposure.

ASCENT provides unique opportunities to advance training and STEM engagement for undergraduate and graduate students, and professionals including Native American and minority populations. Undergraduate and graduate students will gain training in advanced instruments, mid-scale infrastructure development, data management and analysis, and peer mentoring. We will also provide training and educational opportunities for tribal air quality staff and communities, as well as the state and National Park Service site operators.