Methane (CH4) is, after carbon dioxide (CO2), the most important contributor to the anthropogenically enhanced greenhouse effect. Monitoring CH4 abundances in the Earth’s atmosphere is the dedicated goal of several current and future satellite missions. Such space borne observations aim at providing CH4 column concentrations with high sensitivity at the Earth’s surface, with good spatiotemporal coverage, and with sufficient accuracy to facilitate inverse modeling of sources and sinks.
Scattering by aerosols and cirrus clouds is the major challenge for retrievals of methane from space-borne observations of backscattered sunlight in the SWIR spectral range. While contamination by optically thick clouds can be filtered out reliably, optically thin scatterers are much harder to detect, yet still modify the light path of the observed backscattered sunlight and thus can lead to underestimation or overestimation of the true methane column if not appropriately accounted for. The net light path effect strongly depends on the amount, the microphysical properties, and the height distribution of the scatterers as well as on the reflectance of the underlying ground surface. Physics based methods make use of the Oxygen A-band around 760 nm and absorption bands of the target absorber (CH4 and/or CO2) in the SWIR spectral range. The advantage of physics based methods for methane retrieval that they do not depend on accurate prior information on the CO2 column.
USER DOCUMENTATION: ATBD
The Algorithm Theoretical Basis Document (ATBD) can be found by clicking here.
PUM & SAMPLE DATA
The Product User Manual (PUM) and Sample Data Files are being updated based on a new release of the processing software and will be available for download by mid-May 2017.
After launch, preliminary product results will be provided during the Commissioning Phase and the Operational Phase.