Finally, we do not see a relationship between site complexity (assessed by the number of potential emission sources) and alignment in time between CMS solutions. Some complex sites have low alignment (sites 3 and 5), as one might expect, but others have high alignment (site 6). Similarly, some simple sites have high alignment (sites 1 and 4), as one might expect, but others have low alignment (site 2). Ultimately, however, a larger sample of sites is needed to draw any definitive conclusions about the effect of site complexity on localization performance. Each point shows two rate estimates produced during one 30-minute quantification interval. Each subfigure uses data from the two oil and gas sites that have the two solutions installed (see Table ). Axes are restricted to [0, 15] kg/hr to show detail.