Figure 1. Globally averaged atmospheric CH4 (ppb) (a) and its annual growth rate GATM (ppb yr-1) (b) from four measure-
ment programmes: National Oceanic and Atmospheric Adminis- tration (NOAA), Advanced Global Atmospheric Gases Experiment (AGAGE), Commonwealth Scientific and Industrial Research Or- ganisation (CSIRO), and University of California, Irvine (UCI). Detailed descriptions of methods are given in the Supplement of Kirschke et al. (2013). |