This paper quantifies the impact of atmospheric transport and limited marine boundary layer sampling on changes in global and regional methane burdens estimate using tracer transport model simulations with annually repeating methane emissions and sinks but varying atmospheric transport patterns.
Figure 2. The latitudinal dependence of the CH4 growth rate (referred as zonal growth rates in the main) derived using (a) the NOAA method applied to MBL measurements, (b) the TM5 transport-only simulation, and (c) the difference of (a) minus (b). Red colors indicate positive growth rates; blue colors represent negative growth rates. The green numbered growth rate contours are in ppb/year. The yellow vertical lines mark the beginning and end of three periods discussed in the main text: (i) El Niño of 1998, (ii) La Niña of 2010, and (iii) 2014. NOAA = National Oceanic and Atmospheric Administration; MBL = marine boundary layer.