Tribal Representativeness Analysis: Phase II Dave DuBois & Mark Green Desert Research Institute

ZoR Phase 2 Methodology Updated previous work with 2000 to 2004 IMPROVE data Re-ran correlation analysis, computing inter-site correlations for all regions that have at least one IMPROVE or IMPROVE protocol site For those regions with less than 3 we choose nearby sites to make up a total of 4 sites to compute correlation Posted results on COHA website

ZoR Summary cont’d Overall, 84 tribes are not represented by an IMPROVE or IMPROVE protocol site from this task Those not represented are further away from the nearest IMPROVE site than the representative distance

ZoR Results for Mexican Highlands Region

Effects of removing Walker River Including the WARI1 site, the representative distance in the Great Basin region was 98 km After removing the WARI1 site, the representative distance increased to 180 km An increase in the region representative distance implies that the WARI1 site may not correlate with the other sites in one or more fine particle species

Contributions to extinction in 2004 Walker River Notice high NO3, (red) Death Valley Great Basin National Park Zion Canyon

Effects of removing SPOK The Spokane tribal site, SPOK1, was discontinued in June 2005 after collecting over three full calendar years of data Columbia Plateau Region

Spokane analysis Including the SPOK1 site, the representative distance in the Columbia Plateau region was 106 km After removing the SPOK1 site, the representative distance decreased slightly to 102 km A small change of 4 km indicates that the SPOK1 site correlates well with the other sites

Task 2: Considering Terrain Purpose: To investigate the effects of terrain on the representativeness assessment Approached the problem using the HYSPLIT trajectory model Incorporates terrain in the model Successfully used this method in the past Generated trajectories from each IMPROVE site and calculated the number of trajectories passing through an area over each tribe Computed the ratio of the number passing over tribe compared to all trajectories

Example for one day of trajectories Only showing forward trajectories from Death Valley NP July 2, 2005 Example

Task 2 Summary Using a strict criteria that the ratio must be at least 1 at one IMPROVE site in order for a tribe to representative Another choice is to use a ratio of 0.5 (half must go over the tribal area) 49 tribes are not represented by an IMPROVE site considering effects of terrain using ratio = 1

Task 2 Summary

Task 3: Considering Emission Sources Developed a method to compare how polluted each airmass pathway is from a tribe to each IMPROVE site Incorporated the 2002 National Emission Inventory in the data processing for NOx and SO2 Used the 24-hr backward and forward HYSPLIT trajectory database used in previous task

Methodology For each trajectory from an IMPROVE site, calculate the number of times that the trajectory goes over an emission point on route to the tribe Do this many times: generate a forward and backward trajectory 8 times per day, everyday over one year Sum up the emissions for each trajectory cluster Do it for both NOx and SO2 sources Move to the next IMPROVE site and do the same calculation

Ranking Sites We define sites with lower metric scores a better choice for being representative than those with higher scores The sum of emissions over all trajectories was weighted by the distance, R, in kilometers from the tribe to the IMPROVE site The weighting of R2 provides a way to weight the closer sites more than the distant sites

Product for Each Tribe Compare the sum of emissions associated with trajectories from each IMPROVE site Rank the distance from tribe to IMPROVE and emissions from smallest to largest The representative site was the closest IMPROVE site that has trajectories that passed over the least emissions