This project supports the continued operation and management of the Atmospheric Science and Chemistry mEasurement NeTwork (ASCENT). The ASCENT network was developed with support from the NSF Mid-Scale Research Infrastructure program and is providing the first, comprehensive, high time resolution, long-term aerosol data across the United States. It consists of 12 sites in urban, rural, and remote areas that are equipped with a suite of advanced aerosol instrumentation for real-time measurements of fine mode aerosol chemical composition and properties. The ASCENT network fulfills the critical need for long-term, high time-resolution atmospheric aerosol chemistry measurements in the US. for informing science-based policy decisions on air quality related human health and environmental issues. The specific objectives of this project are to: (1) Continue to acquire high time-resolution, high-quality, long-term state-of-the-art measurements of aerosol chemical and physical properties at the 12 established ASCENT sites that are essential to advancing research in air quality, atmospheric science, environmental change, and public health; (2) Develop a database infrastructure for automated quality assurance/control, data upload and download, data discovery and visualization, and long-term data preservation; (3) Enhance training of students and current professionals engaged in science and engineering related to atmospheric air quality research; (4) Conduct research to advance fundame