Surface carbon dioxide concentrations were measured using a non-dispersive infrared carbon dioxide sensor at Lampang Rajabhat University from April to May 2013 and at the University of the Philippines-Diliman campus starting September 2013.  Factors influencing the variations in these measurements were determined using multiple linear regression and a Lagrangian transport model.  Air temperature and sea level pressure were the dominant meteorological factors that affect the CO₂ variations.  However, these factors are not enough. Surface CO₂ flux and...