Effect of Clouds on the Perception of Regional and Urban Haze

摘要

A new method of displaying visual air quality images for surveys has been developed and initial tests completed. The method allows survey participants to continuously control the visual air quality they observe on a monitor to make their judgments. Initial pilot tests of by a few observers viewing urban scenes with & without distant features and with & without cumulus clouds have been completed. Preliminary results indicate that 1. The Phoenix scene which has distant mountains, the addition of clouds appears to make the scene less sensitive to haze, since the scene with clouds was not rated unacceptable until the dv level was 2.6 higher (hazier) than the scene without clouds 2. The St Louis scene which has the most distant building at 1.7 km away, clouds made the scene 5.5 dv more sensitive. 3. Washington DC scene which has more distant features than St Louis but not as far away as Phoenix was in between Phoenix and St Louis in sensitivity to clouds. The results of a larger set of observers will be presented at the conference.