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Back trajectories estimated for the previous 24-hours, ending in Pasadena, CA (red circle) at 14:00 PST. Results are shown for January, March, May, July, September, and November 2015 (from top left to bottom right).  

Back trajectories estimated for the previous 24-hours, ending in Pasadena, CA (red circle) at 14:00 PST. Results are shown for January, March, May, July, September, and November 2015 (from top left to bottom right).  

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We report continuous surface observations of carbon dioxide (CO2) and methane (CH4) from the Los Angeles (LA) Megacity Carbon Project during 2015. We devised a calibration strategy, methods for selection of background air masses, calculation of urban enhancements, and a detailed algorithm for estimating uncertainties in urban scale CO2 and CH4 meas...

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