The Earth Surface Mineral Dust Source Investigation (EMIT) instrument measures surface mineralogy, targeting the Earth’s arid dust source regions. EMIT is installed on the International Space Station (ISS). EMIT uses imaging spectroscopy to take measurements of the sunlit regions of interest between ~52° N latitude and ~52° S latitude. An interactive map showing the locations of methane plumes along with metadata, regions being investigated, current and forecasted data coverage, and additional data resources can be found on the VSWIR Imaging Spectroscopy Interface for Open Science (VISIONS) EMIT Open Data Portal.
EMIT has demonstrated the capacity to characterize methane (CH4) and carbon dioxide (CO2) point-source emissions by measuring gas absorption features in the short-wave infrared bands. The EMIT Level 2B Greenhouse Gas (GHG) series of products can be used to identify and quantify point source emissions. The EMIT Level 2B Estimated Methane Plume Complexes (EMITL2BCH4PLM) Version 2 data product provides estimated methane plume complexes in parts per million meter (ppm m) along with uncertainty data. The EMITL2BCH4PLM data product will only be generated where methane plume complexes have been identified. To reduce the risk of false positives, any EMIT Level 2B Methane Enhancement Data (EMITL2BCH4ENH) granules where plume complexes have been identified undergo a manual review (or identification and confirmation) process before being confirmed as a plume complex. For more information on the manual review process, see section 4.2.4 of the EMIT GHG Algorithm Theoretical Basis Document (ATBD).
Each EMITL2BCH4PLM granule is sized to a specific plume complex but may cross multiple EMITL2BCH4ENH granules. A list of source EMITL2BCH4ENH granules is included in the Cloud Optimized GeoTIFF (COG) file metadata as well as the GeoJSON file. Each EMITL2BCH4PLM granule contains two files: one COG file at a spatial resolution of 60 meters (m) and one GeoJSON file. The EMITL2BCH4PLM COG file contains a raster image of a methane plume complex extracted from EMITL2BCH4ENH v002 data. The EMITL2BCH4PLM GeoJSON file contains a vector outline of the plume complex, a list of source scenes, coordinates of the maximum enhancement values, emission rate estimate, and the uncertainty of the plume complex. The emission rate estimate will be entered as ‘N/A’ if the plume does not meet criteria that are described in Section 4.2.5 of the ATBD.
Known Issues
* Data acquisition gap: From September 13, 2022, to January 6, 2023, a power issue resulted in a shutdown of the EMIT sensor. No data were acquired during that time frame.