Airborne measurements of atmospheric methane over oil fields in western Siberia

Airborne measurements of atmospheric methane (CH 4 ) over oil fields in western Siberia were carried out on August 1, 1994. Extremely sharp CH 4 peaks were observed in the horizontal distribution of CH 4 at an altitude of 150 m above the ground surface; the half widths of the peaks were 3–4 km and the concentration of the largest peak exceeded 2.9 ppmv. Since the CH 4 distribution was considered to reflect the distribution of CH 4 emission strength on the surface, there was strong CH 4 emission at the peak positions. All of the observed CH 4 peak positions were located at or near oil production sites and/or oil pipelines, suggesting that natural gas was emitted from the facilities. Leakage or venting of natural gas are the probable CH 4 sources.