  Matched filter (MF) techniques have been widely used for retrieval of
greenhouse gas enhancements (enh.) from imaging spectroscopy datasets. While
multiple algorithmic techniques and refinements have been proposed, the
greenhouse gas target spectrum used for concentration enh. estimation has
remained largely unaltered since the introduction of quantitative MF
retrievals. The magnitude of retrieved methane and carbon dioxide enh., and
thereby integrated mass enh. (IME) and estimated flux of point-source emitters,
is heavily dependent on this target spectrum. Current standard use of molecular
absorption coefficients to create unit enh. target spectra does not account for
absorption by background concentrations of greenhouse gases, solar and sensor
geometry, or atmospheric water vapor absorption. We introduce geometric and
atmospheric parameters into the generation of scene-specific (SS) unit enh.
spectra to provide target spectra that are compatible with all greenhouse gas
retrieval MF techniques. For methane plumes, IME resulting from use of
standard, generic enh. spectra varied from -22 to +28.7% compared to SS enh.
spectra. Due to differences in spectral shape between the generic and SS enh.
spectra, differences in methane plume IME were linked to surface spectral
characteristics in addition to geometric and atmospheric parameters. IME
differences for carbon dioxide plumes, with generic enh. spectra producing
integrated mass enh. -76.1 to -48.1% compared to SS enh. spectra. Fluxes
calculated from these integrated enh. would vary by the same %s, assuming
equivalent wind conditions. Methane and carbon dioxide IME were most sensitive
to changes in solar zenith angle and ground elevation. SS target spectra can
improve confidence in greenhouse gas retrievals and flux estimates across
collections of scenes with diverse geometric and atmospheric conditions.
