Correlation between RAQMS!dG!n and AIRNow 1-hr surface O!d3!n Correlation between RAQMS!dG!n and AIRNow diurn-avg surface O!d3!n Mean daytime bias of RAQMS!dG!n from AIRNow 1-hr surface O!d3!n Mean nighttime bias of RAQMS!dG!n from AIRNow 1-hr surface O!d3!n Mean observed daytime surface O!d3!n (6-hourly) Mean observed cloudiness (MODIS COT) RAQMS!dG!n 18Z yesterday surface O!d3!n #coincidences and Corr > 0.5 AIRNow 18Z yesterday 1-hr surface O!d3!n #coincidences and Corr > 0.5 AIRNow yesterday maximum 1-hr surface O!d3!n #coincidences and Corr > 0.5 Yesterday observed cloudiness (MODIS COT) #coincidences and Corr > 0.5