The article of record as published may be found at http://dx.doi.org/10.3390/rs9111162Airborne in situ and remote sensing measurements of methane were performed
over the marine seeps in the Santa Barbara Channel close to the Coal Oil Point in California on two
days in June and August 2014 with the aim to re-assess their methane emissions. During this period,
methane column averaged dry air mole fractions derived from airborne remote sensing measurements
in the short-wave infrared and airborne in situ measurements of methane indicate that emissions
are 2–6 kt CH4 y¯1, significantly lower than expected from previous publications. This is also
confirmed by the on ground in situ measurement time series recorded at the onshore West Campus
Monitoring Station in Santa Barbara. Using a time series of methane data, a decline in methane
concentrations between 2008 and 2015 of more than a factor of two was derived for air masses
originating from the seep field direction.NASA Earth Science Division, Research and Analysis ProgramNNX13AM21
