Data from mobile measurements of urban CH4 and C2H6 concentrations in a megacity, Osaka, Japan: Campaign 2023-2024

This dataset provides mobile measurements of CH4 and C2H6 concentrations in the Osaka metropolitan area during 2023-2024. Two types of mobile platforms were employed: a vehicle covering major roads and areas of potential emissions, and a bicycle for narrow streets not accessible by vehicle. Vehicle measurements targeted Osaka and Sakai cities, with additional surveys near known emission sources. Daily measurement areas were predetermined, and repeated observations were limited to key sources. Gas concentrations were measured using a laser-based analyzer (MIRA Ultra), with the sampling inlet positioned 0.5 m above the ground to capture emissions from underground pipelines. Wind speed and direction were recorded via a sonic anemometer, and position data via GPS, all logged at 1-second intervals. Sampling lag times were corrected using calibration with known CH4 concentrations. Bicycle measurements employed the same analyzer and inlet height, logging CH4 and C2H6 concentrations with GPS at 1-second intervals.