The Earth Surface Mineral Dust Source Investigation (EMIT) is an Earth Ventures-Instrument (EVI-4) Mission on board the International Space Station (ISS). EMIT’s prime mission was designed to map surface mineralogy of arid dust source regions via imaging spectroscopy in the visible and short-wave infrared (VSWIR). EMIT uses imaging spectroscopy to take mineralogical measurements of sunlit regions of interest between 52° N latitude and 52° S latitude. During the prime mission, the EMIT team focused on using surface reflectance to resolve absorption features of iron oxides, clays, sulfates, carbonates, and other dust-forming minerals in Earth's dust source regions. In the extended mission, EMIT’s core measurements remain the same, but acquisitions expand to sample all regions observable from the ISS orbit, supporting efforts across the atmosphere, biosphere, cryosphere, geosphere, hydrosphere, and more. An interactive map showing the 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.

In addition to its primary objective described above, EMIT has demonstrated the capacity to characterize methane (CH4) and carbon dioxide (CO2) point-source emissions by measuring gas absorption features in the shortwave infrared bands. The EMIT Level 2B Carbon Dioxide Enhancement Data (EMITL2BCO2ENH) Version 3 data product is a total vertical column enhancement estimate of carbon dioxide in parts per million meter (ppm m) based on an adaptive matched filter approach. A Differential Matched Filter (DiffMF) approach has been introduced along with this Version 3 data product to help reduce the inclusion of false-positive plume complexes. The code used to produce the enhancements and uncertainties can be found in the EMIT science data system GitHub repository. EMITL2BCO2ENH provides per-pixel carbon dioxide enhancement data used to identify carbon dioxide plume complexes, per-pixel differential matched filter results to reduce false-positive identification of methane plume complexes, per-pixel carbon dioxide uncertainty due to sensor noise, and per-pixel carbon dioxide sensitivity that can be used to understand sources of bias in the enhancement data.

The EMITL2BCO2ENH Version 3 data product includes carbon dioxide enhancement granules for all captured scenes, regardless of carbon dioxide plume complex identification. Each granule contains five Cloud Optimized GeoTIFF (COG) files at a spatial resolution of 60 meters (m) and one full resolution browse image: Carbon Dioxide Enhancement (EMIT_L2B_CO2ENH), Carbon Dioxide Uncertainty (EMIT_L2B_CO2UNCERT), Carbon Dioxide DiffMF bands 1 and 2 (EMIT_L2B_CO2ENHD1, EMIT_L2B_CO2ENHD2), and Carbon Dioxide Sensitivity (EMIT_L2B_CO2SENS). The EMITL2BCO2ENH COG files contain carbon dioxide enhancement data based primarily on EMIT L1B At-Sensor Calibrated Radiance (EMITL1BRAD) values.

Each granule is approximately 75 kilometers (km) by 75 km, nominal at the equator, with some granules near the end of an orbit segment reaching 150 km in length.

Known Issues

• Data acquisition gap: From September 13, 2022, through January 6, 2023, a power issue on the ISS caused a pause in EMIT operations. Due to this shutdown, no data were acquired during that timeframe. Outside of this period, regular short-term gaps in coverage are expected depending on the solar and sensor geometry.