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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). 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 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 L2A Masks 60 m (EMITL2AMASK) Version 2 data product provides a series of masks to assist in identification of clear and reliable observations of the Earth’s surface in a spatially raw, non-orthocorrected format. Each EMITL2AMASK granule consists of one Network Common Data Format 4 (netCDF-4) file at a spatial resolution of 60 meters (m) along with a corresponding browse image. The data file (EMIT_L2A_MASK) contains eleven mask bands: seven binary flag bands and four 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), water vapor, probability of cloud presence, and distance to nearest cloud pixel.

The netCDF-4 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 file will also contain latitude, longitude, and elevation variables. The latitude and longitude coordinates are presented using the World Geodetic System 84 (WGS-84) ellipsoid. The elevation data was obtained from Shuttle Radar Topography Mission v3 (SRTM v3) data and is resampled to EMIT’s spatial resolution.

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

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.

Version Description

While EMITL2AMASK Version 2 is a new product, the six binary bands that identify clouds, water, and spacecraft and the two data bands that contain AOD and water vapor data were originally provided in the EMIT L2A Reflectance (EMITL2ARFL) Version 1 (https://doi.org/10.5067/EMIT/EMITL2ARFL.001) product. EMITL2AMASK includes an additional binary cloud flag band and two data bands from the new deep learning Spectroscopic Transformer (SpecTf) model (https://doi.org/10.1073/pnas.2502903122).

Product Summary

Platforms
ISS
Instruments
EMIT Imaging Spectrometer
Spatial Extent

N: 54 S: -54 E: 180 W: -180

Spatial Resolution
60 Meters x 60 Meters
Geographic Region
GLOBAL LAND
Coordinate System
CARTESIAN
Granule Spatial Representation
GEODETIC
Temporal Extent
2022-08-09 to Present
Temporal Resolution
Varies
Data Partner
Land Processes Distributed Active Archive Center (LP DAAC) ,
Earth Surface Mineral Dust Source Investigation, Jet Propulsion Laboratory, NASA (NASA/JPL/EMIT)
Concept ID
C3882545269-LPCLOUD
Data State
ACTIVE
Number of Files/Granules
199165
Processing Level
2A
Published
Science Keywords
Atmospheric Water Vapor ,
Clouds ,
Aerosol Optical Depth/Thickness

Citation

Citation is critically important for dataset documentation and discovery. This dataset is openly shared, without restriction, in accordance with the EOSDIS Data Use and Citation Guidance.

Copy Citation

Brodrick, P., Lee, J., Kiper, M., Chlus, A., Olson-Duvall, W., Lundeen, S., Thompson, D., & Green, R. (2025). EMIT L2A Masks 60 m V002 [Data set]. NASA Land Processes Distributed Active Archive Center. https://doi.org/10.5067/EMIT/EMITL2AMASK.002 Date Accessed: 2026-01-10

File Naming Convention

EMIT_L2A_MASK_002_20250916T020844_2525902_004.nc

The file name begins with the Sensor (EMIT) followed by the Processing Level (L2A), Product Type (MASK), Product Version Number (002), Date and Time of Acquisition designated as YYYYMMDDTHHMMSS (20250916T020844), Orbit Identification Number (2525902), Scene Identification Number (004), and the Data Format (nc).

Documents

Variables

Variables are a set of physical properties whose values determine the characteristics or behavior of something. For example, temperature and pressure are variables of the atmosphere. Parameters and variables can be used interchangeably. Variable level attributes provide individual information for each variable.

The Name in this table is the variable name. Fill value indicates missing or undefined data points in a variable. Valid range is the range of values the variable can store. Scale factor is used to increase or decrease the size of an object and can be used to correct for distortion. For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor
elev Surface Elevation Meters float64 -9999 N/A N/A
glt_x Geometric Lookup Table (GLT) Sample Lookup N/A int32 0 1 to 1242 N/A
glt_y GLT Line Lookup N/A int32 0 1 to 2559 N/A
lat Latitude (WGS-84) Decimal Degree float64 -9999 -90 to 90 N/A
lon Longitude (WGS-84) Decimal Degree float64 -9999 -180 to 180 N/A
mask Masks N/A float32 -9999 N/A N/A
mask_bands Array of strings indicating the name of each mask band N/A string N/A N/A N/A
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