Abstract: This method comprises: obtaining first data representative of amounts of a first gas and second data representative of amounts of a second tracer gas emitted by the source together with the first gas, calculating at least one coefficient of correlation between the amounts of the first gas and the amounts of the second gas from the first representative data and the second representative data; obtaining a measured or computed flow of the second gas emitted by the source; computing a flow of the first gas emitted by the source on the basis of the measured or computed flow of the second gas emitted by the source and the correlation coefficient.

Abstract: This method comprises the following steps retrieving data about amounts of at least one gas, said data being measured in the atmosphere at a distance from the source along a plurality of lines parallel to a first direction; integrating the amounts read on each line in the first direction in order to obtain an integrated overall amount on each line; integrating the product of the integrated overall amounts on each line and a wind speed present on the line in a second direction perpendicular to the first direction, in order to obtain a raw flow of gas; determining the flow of gas emitted by the source based on the raw flow of gas.