Performance and sensitivity of column-wise and pixel-wise methane retrievals for imaging spectrometers

Airborne imaging spectrometers are increasingly used to map methane (CH4) at high spatial resolution (e.g., 3-5 m). This study presents an analysis of two common approaches to retrieve methane from imaging spectrometer data. The approaches are (1) the columnwise matched filter (CMF), and (2) the physics-based Iterative Maximum A Posteriori – Differential Optical Absorption Spectroscopy (IMAP-DOAS). We use data from a single-blind controlled release experiment to assess the performance of these two retrieval algorithms. We find that the length of the column in the CMF has a large impact on the quantitative results of the CMF and can results in low emissions estimates if proper column length standards are not met. We also find that the IMAP-DOAS derived emission rates showing strong correlation and little bias compared to the in-situ emissions measurements.