Methane mole fraction and δ13C above and below the Trade Wind Inversion at Ascension Island in air sampled by aerial robotics

摘要: Ascension Island is a remote South Atlantic equatorial site, ideal for monitoring tropical background CH4. In September 2014 and July 2015, octocopters were used to collect air samples in Tedlar bags from different heights above below the well-defined Trade Wind Inversion (TWI), sampling maximum altitude of 2700 meters mean sea-level. Sampling captured both marine boundary layer TWI, also masses TWI that had been lofted by convective systems African tropics. Air was characterized higher CH4 but no distinct shift δ13C observed compared below. Back-trajectories indicate emissions southern hemisphere Africa have bulk δ13CCH4 signatures similar background, suggesting mixed wetlands, agriculture biomass burning. The campaigns illustrate usefulness UAS sampling, Ascension's value atmospheric measurement an understudied region.