Figure 2
From: Evaluating methane inventories by isotopic analysis in the London region
Observations at KCL roof on the 20th and 21st January 2014: (a) CH4 and CO2 mole fractions profiles (b) Keeling plots based on the samples collected during the 20th and the early morning of the 21st January 2014 (white markers), during the morning of the 21st January 2014 (black markers), and background (grey marker) with the order of sampling (dotted line). (c) Wind direction (grey line), wind speed (line, inset graph) and CH4 mole fractions (black line). Time interval of those samples that are thought to be associated with a biogenic CH4 source indicated by grey shading.
