Mw. Gallagher et al., MEASUREMENTS OF METHANE FLUXES ON THE LANDSCAPE SCALE FROM A WETLAND AREA IN NORTH SCOTLAND, Atmospheric environment, 28(15), 1994, pp. 2421-2430
Atmospheric profiles of methane have been measured using an aircraft o
ver an area of natural wetland in Northern Britain, Caithness and Suth
erland, in Scotland. The measurements showed a clear horizontal gradie
nt in methane concentration as air was advected over the wetland area
from the Atlantic Ocean and a strong decrease in concentration in the
vertical. The data, together with those from ground-based measurements
including continuous measurements at an instrumented field site, were
used to estimate area averaged fluxes using a simple diffusion model.
The mean flux for the region was calculated to be 0.91 +/- 0.51 mug m
-2 s-1. Methane source strengths for the NW region of Scotland were a
factor of 2-3 times larger than for the NE region. Nocturnal methane f
luxes were estimated at the field site from temporal concentration cha
nges in methane near the surface and doppler sodar measurements of the
boundary layer depth. Night time fluxes were found to be 0.45 +/- 0.2
8 mug m-2 s-1 and were comparable to those measured using the flux gra
dient technique at the same site. The aircraft area averaged fluxes we
re typically a factor of 2-4 times larger than those measured by cuvet
te techniques at the surface. This was probably due to the dryness of
the site relative to the area to the west.