Quantifying Methane Emission from Surface Sources using the Backward Lagrangian Stochastic Method

The subject of this thesis is the micrometeorological estimation of the rate of transfer ("flux") of gases from surface area sources to the atmosphere. More specifically, it is an investigation of a particular implementation of the "inverse dispersion" method (ID), whereby rather than measuring the wanted flux directly, one instead measures the gas concentration rise attributable to the source, and deduces the flux necessary to explain that measurement under the prevailing meteorological conditions. The ID method used here is called "bLS" for "backward Lagrangian stochastic", a name which alludes to the type of meteorological models used to relate the flux (Q) to the concentration rise (ΔC). The thesis will demonstrate the practicalities involved in implementing bLS to quantify methane emission both from well defined, homogeneous sources and also from inhomogeneous, scattered, and poorly delineated source areas on complex topography.