EMITL2BMIN v001

EMIT L2B Estimated Mineral Identification and Band Depth and Uncertainty 60 m


PI: Robert Green

Description

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 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 2B Estimated Mineral Identification and Band Depth and Uncertainty (EMITL2BMIN) Version 1 data product provides estimated mineral identification and band depths in a spatially raw, non-orthocorrected format. Each EMITL2BMIN granule contains two Network Common Data Format 4 (NetCDF4) files at a spatial resolution of 60 meters (m): Mineral Identification (EMIT_L2B_MIN) and Mineral Uncertainty (EMIT_L2B_MINUNCERT). The EMIT_L2B_MIN file contains the band depth (the depth of the identified spectral feature) and the identified mineral for each pixel. Two spectral groups, which correspond to different regions of the spectra, are identified independently and often co-occur. These estimates are generated using the Tetracorder system (code) and are based on EMITL2ARFL reflectance values. The EMIT_L2B_MINUNCERT file provides band depth uncertainty estimates calculated using surface Reflectance Uncertainty values from the EMITL2ARFL data product. The band depth uncertainties are presented as standard deviations. The fit score for each mineral identification is also provided as the coefficient of determination (r2) of the match between the continuum normalized library reference and the continuum normalized observed spectrum. Associated metadata indicates the name and reference information for each identified mineral, and additional information about aggregating minerals into different categories is available in the emit-sds-l2b repository and will be available as subsequent data products.

The EMITL2BMIN data product includes a total of 19 Science Dataset (SDS) layers. There are four layers for each of the Spectral Groups (Group 1 and Group 2): Mineral Identification, Band Depth, Band Depth Uncertainties, and Fit Score. Additional layers consist of geometric lookup table (GLT) x values, GLT y values, latitude, longitude, elevation, associated spectral library record, mineral name, URL for the spectral library description, spectral group, spectral library, and spectral group index. A browse image with Group 1 Band Depth, Group 2 Band Depth, Group 1 Band Depth Uncertainty, and Group 2 Band Depth Uncertainty is also included.

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

Disclaimer

This product is generated to support the EMIT mission objectives of constraining the sign of dust related radiative forcing. Ten mineral types are the core focus of this work: calcite, chlorite, dolomite, goethite, gypsum, hematite, illite+muscovite, kaolinite, montmorillonite, and vermiculite. A future product will aggregate these results for use in Earth System Models. Additional minerals are included in this product for transparency but were not the focus of this product. Further validation is required to use these additional mineral maps, particularly in the case of resource exploration. Similarly, the separation of minerals with similar spectral features, such as a fine-grained goethite and hematite, is an area of active research. The results presented here are an initial offering, but the precise categorization is likely to evolve over time, and the limits of what can and cannot be separated on the global scale is still being explored. The user is encouraged to read the Algorithm Theoretical Basis Document (ATBD) for more details.

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Characteristics

Collection and Granule

Collection

Characteristic Description
CollectionEMIT
DOI10.5067/EMIT/EMITL2BMIN.001
File Size~120 MB
Temporal ResolutionVaries
Temporal Extent2022-08-09 to Present
Spatial ExtentGlobal (52 °N to 52 °S Latitude)
Coordinate SystemGeographic Latitude and Longitude
DatumWorld Geodetic System (WGS84)
File FormatnetCDF-4
Geographic Dimensions74.5 km x 76.8 km

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers19
Columns/Rows1242 x 1280
Pixel Size60 m

Layers / Variables

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
group_1_band_depth1 Group 1 Band Depth N/A 32-bit floating point N/A -9999.00 0 to 1 N/A
group_1_mineral_id1 Group 1 Mineral ID N/A 16-bit signed integer N/A -9999 0 to 294 N/A
group_2_band_depth1 Group 2 Band Depth N/A 32-bit floating point N/A -9999.00 0 to 1 N/A
group_2_mineral_id1 Group 2 Mineral ID N/A 16-bit signed integer N/A -9999 0 to 294 N/A
group_1_band_depth2 Group 1 Band Depth Uncertainty N/A 32-bit floating point N/A -9999.0 0 to 1 N/A
group_1_fit2 Group 1 Fit N/A 32-bit floating point N/A -9999.0 0 to 1 N/A
group_2_band_depth2 Group 2 Band Depth Uncertainty N/A 32-bit floating point N/A -9999.0 0 to 1 N/A
group_2_fit2 Group 2 Fit N/A 32-bit floating point N/A -9999.0 0 to 1 N/A
glt_x3 Geometric lookup table – x values N/A 32-bit signed integer -9999 0 1 to 1242 N/A
glt_y3 Geometric lookup table – y values N/A 32-bit signed integer -9999 0 1 to 2559 N/A
lat3 Latitude Degree 64-bit floating point -9999.0000 N/A -90 to 90 N/A
lon3 Longitude Degree 64-bit floating point -9999.0000 N/A -180 to 180 N/A
elev3 Elevation Meters 64-bit floating point -9999.0000 N/A N/A N/A
index1 Index matching the group 1 or group 2 mineral ID N/A 32-bit unsigned integer 4294957297 N/A N/A N/A
record1 Record in the associated spectral library N/A 32-bit unsigned integer 4294957297 N/A N/A N/A
name1 Mineral Name N/A string N/A N/A N/A N/A
url1 Link to USGS Spectral Library 7 Description (if available) N/A string N/A N/A N/A N/A
group1 Which mineral spectral group the index belongs to (1 or 2) N/A 32-bit unsigned integer 4294957297 N/A N/A N/A
library1 Spectral library index corresponds to N/A string N/A N/A N/A N/A

1 EMIT_L2B_MIN
2 EMIT_L2B_MINUNCERT
3 EMIT_L2B_MIN and EMIT_L2B_MINUNCERT
Scenes have at least 1280 rows. To prevent small scenes, scenes at the end of an orbit segment will have up to 2559 rows.

Product Quality

Quality information for the EMITL2BMIN Version 1 data product is not provided.

Known Issues

  • Data acquisition gap: From September 13, 2022, through January 6, 2023, a power issue resulted in a shutdown of the EMIT sensor. Due to this shut down no data was acquired during that timeframe.

About the image

Group 2 Band Depth data from the EMITL2BMIN version 1 product over the Gobi Desert in southern Mongolia, Asia on August 11, 2022.

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Documentation

User Guide
Algorithm Theoretical Basis Document (ATBD)

Using the Data

E-Learning

Access Data

Citation

DOI: 10.5067/EMIT/EMITL2BMIN.001