IMPROVE Network Assessment Plans

IMPROVE Network Assessment Motivation: –EPA’s air quality monitoring budget is not growing, but their requirements are changing and expanding –Thus far their support of IMPROVE particle speciation has not been affected –EPA’s level of support for IMPROVE will be reviewed next year

IMPROVE Network Assessment Objectives: With respect to their utility for meeting federal visibility protection requirements –Identify monitoring sites whose data are essentially redundant to that of other sites –Identify likely spatial gaps in the network –Prioritize the IMPROVE & Protocol sites –Document the assessment in a report to EPA

IMPROVE Network Assessment Tentative technical approach –Identify neighboring sites who’s primary particulate composition data have similar magnitudes and seasonal variations, and are highly correlated (compared to collocated samplers) –Assess current network’s coverage in regions where anticipated emission changes are likely to significantly alter current spatial concentration gradients (could use CAIR modeling) –Compare results with the original IMPROVE criteria for representative monitoring (horizontal distance < 100km, elevation within class I area range +100ft or +10%) –Evaluate budget consequences of network reconfigurations (cost to add or remove sites)

IMPROVE Network Assessment Management approach options: –Have existing IMPROVE team perform the assessment (CIRA, UCD, one of the sponsoring agencies, or some combination) –Contract for the assessment Related activities: –IMPROVE report being planned by CIRA –RPO’s are preparing a Regional Haze Monitoring Strategy document –WRAP tribal monitoring needs assessment –Other related activities?

There’s a natural tendency to want to group sites to simplify analysis. Does that mean we only need one or two sites in a group? Shown here are groupings by WRAP based on similar haze contributions by each state’s point and mobile sources using CMAQ modeling. Others have done groupings of IMPROVE monitoring sites. Is there value in using groupings to assess the IMPROVE network sites?

Are sites with different major component contributing to annual 20% worst haze days an indication that each site is necessary? How similar do the contribution to haze data need to be? How important are similar seasonal patterns for 20% worst haze days in assessing whether a pair of sites are redundant? How similar would they need to be?

Correlation coefficients between paired composition data tend to decrease with distance between sites. Even for sulfur that is pretty uniform over large regions, the correlation coefficient is less than 0.8 at ~100km spacing between sites. Is r > 0.8 similar enough that one of the sites could be removed? Is this a reasonable way to evaluate the IMPROVE network?