- ItemOpen AccessIMPROVE (Interagency Monitoring of Protected Visual Environments): spatial and seasonal patterns and temporal variability of haze and its constituents in the United States: report VI(Colorado State University. Libraries, 2023) Hand, Jenny, author; Copeland, Scott, author; Chow, Judy, author; Dillner, Ann, author; Hyslop, Nicole, author; Malm, William, author; Prenni, Anthony, author; Raffuse, Sean, author; Schichtel, Bret, author; Watson, John, author; Young, Dominique, author; Zhang, Xiaolu, author; Colorado State University, publisherThe Interagency Monitoring of Protected Visual Environments (IMPROVE) program is a cooperative measurement effort between the U. S. Environmental Protection Agency (EPA), federal land management agencies, and state agencies. The network is designed to (1) establish current visibility and aerosol conditions in 156 mandatory Class I areas, (2) identify chemical species and emission sources responsible for existing anthropogenic visibility impairment, (3) document long-term trends for assessing progress towards the national visibility goal, and (4) provide regional haze monitoring representing all visibility-protected federal CIAs where practical. Although the program is focused on visibility objectives, the data acquired and the methodologies developed by the IMPROVE network have been broadly used to address air quality management related to human health, climate change, ecosystem degradation, and material damage. This report is the sixth in a series that describes the monitoring methods and changes to instrumentation over time, as well as reports on measured aerosol concentrations and aerosol-derived visibility estimates.