EMIT L1B Corrected Spacecraft Attitude and Ephemeris V001

The Earth Surface Mineral Dust Source Investigation (EMIT) is an Earth Ventures-Instrument (EVI-4) Mission aboard the International Space Station (ISS). EMIT’s prime mission was designed to map surface mineralogy of arid dust source regions using imaging spectroscopy in the visible and short-wave infrared (VSWIR) range. 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. The EMIT Level 1B Corrected Spacecraft Attitude and Ephemeris (EMITL1BATT) Version 2 data product provides both corrected and uncorrected attitude quaternions and spacecraft ephemeris data obtained from the ISS, including Earth-centered inertial (ECI) position and velocity, along with associated time elements. The data are provided in one second intervals and each product file contains vectors from the duration of the orbit. The time elements are copied from the ISS raw data. The data for each EMITL1BATT granule are delivered in a single Network Common Data Format Version 4 (netCDF-4) file. 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.

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) and uses imaging spectroscopy to take mineralogical measurements of sunlit regions of interest between 52° N latitude and 52° S latitude. 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. The EMIT Level 1B At-Sensor Calibrated Radiance and Geolocation (EMITL1BRAD) Version 1 data product provides at-sensor calibrated radiance values along with observation data in a spatially raw, non-orthocorrected format. Each EMITL1BRAD granule consists of two Network Common Data Format 4 (NetCDF4) files at a spatial resolution of 60 meters (m): Radiance (EMIT_L1B_RAD) and Observation (EMIT_L1B_OBS). The Radiance file contains the at-sensor radiance measurements of 285 bands with a spectral range of 381-2493 nanometers (nm) and with a spectral resolution of ~7.5 nm, which are held within a single science dataset layer (SDS). The Observation file contains viewing and solar geometries, timing, topographic, and other information related to the observation. Each NetCDF4 file holds a location group containing geometric lookup tables (GLT), which are orthorectified images that provide relative x and y reference locations from the raw scene to allow for projection of the data. Along with the GLT layers, the files also contain latitude, longitude, and elevation layers. The latitude and longitude coordinates are presented using the World Geodetic System (WGS84) ellipsoid. The elevation data was obtained from Shuttle Radar Topography Mission v3 (SRTM v3) data and resampled to EMIT’s spatial resolution. Each granule is approximately 75 kilometers (km) by 75 km, nominal at the equator, with some granules at 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 outside of EMIT caused a pause in operations. Due to this shutdown, no data were acquired during that timeframe.

The Earth Surface Mineral Dust Source Investigation (EMIT) is an Earth Ventures-Instrument (EVI-4) Mission aboard the International Space Station (ISS). EMIT’s prime mission was designed to map surface mineralogy of arid dust source regions using imaging spectroscopy in the visible and short-wave infrared (VSWIR) range. 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. The EMIT Level 1B At-Sensor Calibrated Radiance and Geolocation (EMITL1BRAD) Version 2 data product provides at-sensor calibrated radiance values along with observation data in a spatially raw, non-orthocorrected format. Each EMITL1BRAD granule consists of two Network Common Data Format Version 4 (netCDF-4) files at a spatial resolution of 60 meters (m): Radiance (EMIT_L1B_RAD) and Observation (EMIT_L1B_OBS). The Radiance file contains the at-sensor radiance measurements of 285 bands with a spectral range of 381-2493 nanometers (nm) and with a spectral resolution of ~7.5 nm, all held within a single variable. The Observation file contains viewing and solar geometries, timing, topographic, and other information related to the observation. Each netCDF-4 file holds a location group containing geometric lookup tables (GLT), which are orthorectified images that provide relative x- and y-reference locations from the raw scene to allow for projection of the data. Along with the GLT layers, the files also contain latitude, longitude, and elevation layers. The latitude and longitude coordinates are presented using the World Geodetic System (WGS84) ellipsoid. The elevation data was obtained from Shuttle Radar Topography Mission v3 (SRTM v3) data and then resampled to EMIT’s spatial resolution. Each granule is approximately 75 kilometers (km) by 75 km, nominal at the equator, with some granules at the end of an orbit segment reaching approximately 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.

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) and 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 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. The EMIT Level 4 Earth System Model (EMITL4ESM) Version 1 data product provides radiative forcing outputs, along with other ancillary outputs generated from different Earth System Models (ESMs). ESMs are complex models that integrate relevant physical, chemical, biological, and human components to simulate multiple aspects of large-scale systems on Earth. Multiple models, input mineral maps, meteorology inputs, and emissions/concentration scenarios are examined for the model runs contained within this data product. Models currently utilized include the Community Earth System Model 2 (CESM2) and the Goddard Institute for Space Studies (GISS) model. Some ESM runs utilize reference surface mineral maps from the literature dating back to 2007; others rely on the EMIT L3 Aggregated Mineral Spectral Abundance and Uncertainty 0.5 Deg (EMITL3ASA) data as inputs. Each EMITL4ESM granule represents a single ESM run with a Network Common Data Format 4 (netCDF-4) file for each variable. A total of 12 Science Dataset (SDS) layers or variables are provided for each model run. For some SDS layers or variables, multiple layers based on inclusion of model minerology inputs are provided in their netCDF files. The layers/variables table below details which variables contain the extra layers. Metadata flags for Earth System Model, Resolution, Surface Mineral Map, External Meteorology, Time Period, and Emissions/Concentration Scenario indicate the key parameters for each granule. A table outlining each variable in detail can be found in the EMIT Science Data System Level 4 repository. Known Issues * Data acquisition gap: From September 13, 2022, through January 6, 2023, a power issue outside of EMIT caused a pause in operations. Due to this shutdown, no data were acquired during that timeframe.

The Earth Surface Mineral Dust Source Investigation (EMIT) is an Earth Ventures-Instrument (EVI-4) Mission aboard the International Space Station (ISS). EMIT’s prime mission was designed to map surface mineralogy of arid dust source regions using 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. The EMIT Level 3 Gridded Surface Reflectance and Uncertainty (EMITL3RFL) Version 2 data product provides surface reflectance, uncertainty, atmospheric state, and observation data which are projected to a regular grid using World Geodetic System 1984 (WGS 84). The pixel size of the grid is 0.00055 degrees, corresponding to an approximate spatial resolution of 60 meters (m). Each EMITL3RFL granule consists of three Network Common Data Format Version 4 (netCDF-4) files (gridded Reflectance, gridded Reflectance Uncertainty, gridded Observation), one sidecar JSON (JavaScript Object Notation) file, and one full-resolution browse image. The Reflectance file (EMIT_L3_RFL) contains surface reflectance maps of 285 bands with a spectral range of 381-2493 nanometers (nm) at a spectral resolution of ~7.5 nm. These are all contained within a single science dataset layer/variable. Aerosol optical thickness and water vapor values are also included within their own separate variables. The Reflectance Uncertainty file (EMIT_L3_RFLUNCERT) contains uncertainty reported as one standard deviation, per channel, with covariance ignored. The Observation file (EMIT_L3_OBS) contains variables with viewing and solar geometries, timing, aspect, slope, and other information related to the observation for each pixel. The spectral information provided within each granule is the same as EMIT L2A Surface Reflectance and Uncertainty 60 m V002 (EMITL2ARFL), that has been orthorectified and had the cloud mask applied in advance. Each netCDF-4 file is also chunked and compressed into five precision fragments, to provide more efficient file access, particularly for cloud-access interfaces. The JSON sidecar file (EMIT_L3_RFL*.sidecar.json) is an optional file that may decrease the latency for some cloud-access interfaces. Each granule is approximately 75 kilometers (km) by 75 km, nominal at the equator, with some reaching approximately 150 km in length at the end of an orbit segment. 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.

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) and uses imaging spectroscopy to take mineralogical measurements of sunlit regions of interest between 52° N latitude and 52° S latitude. 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. The EMIT Level 2A Estimated Surface Reflectance and Uncertainty and Masks (EMITL2ARFL) Version 1 data product provides surface reflectance data in a spatially raw, non-orthocorrected format. Each EMITL2ARFL granule consists of three Network Common Data Format 4 (NetCDF4) files at a spatial resolution of 60 meters (m): Reflectance (EMIT_L2A_RFL), Reflectance Uncertainty (EMIT_L2A_RFLUNCERT), and Reflectance Mask (EMIT_L2A_MASK). The Reflectance file contains surface reflectance maps of 285 bands with a spectral range of 381-2493 nanometers (nm) at a spectral resolution of ~7.5 nm, which are held within a single science dataset layer (SDS). The Reflectance Uncertainty file contains uncertainty estimates about the reflectance captured as per-pixel, per-band, posterior standard deviations. The Reflectance Mask file contains six binary flag bands and two data bands. The binary flag bands identify the presence of features including clouds, water, and spacecraft which indicate if a pixel should be excluded from analysis. The data bands contain estimates of aerosol optical depth (AOD) and water vapor. Each NetCDF4 file holds a location group containing a geometric lookup table (GLT) which is an orthorectified image that provides relative x and y reference locations from the raw scene to allow for projection of the data. Along with the GLT layers, the files will also contain latitude, longitude, and elevation layers. The latitude and longitude coordinates are presented using the World Geodetic System (WGS84) ellipsoid. The elevation data was obtained from Shuttle Radar Topography Mission v3 (SRTM v3) data and resampled to EMIT’s spatial resolution. Each granule is approximately 75 kilometers (km) by 75 km, nominal at the equator, with some granules at 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 outside of EMIT caused a pause in operations. Due to this shutdown, no data were acquired during that timeframe. * Possible Reflectance Discrepancies: Due to changes in computational architecture, EMITL2ARFL reflectance data produced after December 4, 2024, with Software Build 010621 and onward may show discrepancies in reflectance of up to 0.8% in extreme cases in some wavelengths as compared to values in previously processed data. These discrepancies are generally lower than 0.8% and well within estimated uncertainties. Between earlier builds and Build 010621, neither resulting output should be interpreted as more ‘correct’ than the other, as their results are simply convergence differences from an optimization search. Most users are unlikely to observe the impact.