Skip to main content

The Earth Surface Mineral Dust Source Investigation (EMIT) Imaging Spectrometer is a NASA Earth Venture Instrument (EVI-4) mounted to the exterior of the International Space Station (ISS). EMIT is the first instrument to use NASA-invented imaging spectroscopy technology to comprehensively measure the different wavelengths of light emitted by minerals on the surface of deserts and other dust sources to determine their composition.

In 2024, EMIT passed into an extended mission phase of operations, and will continue to collect data through at least 2026.

EMIT Filenames

EMIT filenames (i.e., the local granule ID) follow a naming convention which gives useful information regarding the specific product.

Level 1 and 2 data product filenames will adhere to the following naming convention: EMIT_L1B_RAD_001_20220101T083015_2200105_007

  • EMIT – Sensor
  • L1B – Product Level
  • RAD – Product Type
  • 001 – Product Version Number
  • 20220101 – Date of Acquisition (YYYYMMDD)
  • T083015 – Time of Acquisition (HHMMSS) (in UTC)
  • 2200105 – Orbit identification number (YYDOYNN), where NN is a two-digit incrementing orbit number for each day
  • 007 – Scene identification number

Level 2B Estimated Methane Plume Complexes cloud optimized GeoTIFF filenames adhere to the following naming convention: EMIT_L2B_CH4PLM_001_20220101T083015_000120

  • EMIT – Sensor
  • L2B – Product Level
  • CH4PLM – Product Type
  • 001 – Product Version Number
  • 20220101 – Date of Acquisition (YYYYMMDD)
  • T083015 – Time of Acquisition (HHMMSS) (in UTC)
  • 000120 – Unique global plume complex identifier

For level 3 and 4 data products, filenames will follow the naming convention: EMIT_L3_ASA_001

  • EMIT – Sensor
  • L3 – Product Level
  • ASA – Product Type
  • 001 – Product Version Number

Each EMIT product may contain multiple NetCDF files and one quick look PNG file. The PNG file name will match the main product of the collection but will have PNG as the data format. For example, the EMITL1BRAD data product contains two separate NetCDF files: radiance (EMIT_L1B_RAD_001_20220101T083015_2200105_007.nc) and observation (EMIT_L1B_OBS_001_20220101T083015_2200105_007.nc). The browse file will be EMIT_L1B_RAD_001_20220101T083015_2200105_007.png.

EMIT Product Long Name

The EMIT Product Long Name (i.e., Collection-Level) naming convention provides useful information regarding all EMIT swath products.

Below is an example for an EMIT Level 1B product, although all EMIT Product Long Names follow the same structure.

The EMIT L1B At-Sensor Calibrated Radiance and Geolocation Data 60 m V001 collection has the following characteristics:

  • EMIT – Instrument
  • L1B – Processing Level
  • At-Sensor Calibrated Radiance and Geolocation Data – Geophysical Parameter
  • 60 m – Spatial Resolution
  • V001 – Version Number

EMIT Processing Levels

EMIT data products will follow NASA's Earth Observing System Data and Information System (EOSDIS) data processing levels.

LP DAAC distributes EMIT data processed to Level 1 or higher:

  • Level 1B: Calibrated Radiance and Geolocation Data, Refined Attitude/Ephemeris
  • Level 2A: Surface Reflectance and Mask Data
  • Level 2B: Estimated Mineral Identification, Band Depth, and Uncertainty Data
  • Level 3: Aggregated Mineral Abundance Maps
  • Level 4: Earth System Model Runs

EMIT Processing Description

The EMIT mission generates five distributable data products that represent four levels of data processing. EMIT starts and stops data recording based on a surface coverage mask. This period of data recording within an orbit is referred to as a scene and can cover thousands of kilometers down-track. The area covered depends on the acquisition mask map. For the sake of convenience, each scene is broken into granules of 1280 down-track lines which can be reassembled seamlessly into scenes. The last granule can be extended up to 2559 lines to prevent having a granule with very few lines. As a scene is collected, the raw data are stored on a high-speed Solid-State Data Recorder (SSDR). From there the avionics software reads the uncompressed data, packages it into frames of 32 instrument lines, screens the frames for cloudy pixels, and then performs a lossless 4:1 compression of the processed science data before storing it back onto the SSDR. The data is then downlinked to the EMIT Instrument Operation System (IOS) and delivered to the Science Data System (SDS) where Level 0 processing occurs. The Level 0 data is then further processed into Level 1B, Level 2A, Level 2B, and Level 3 data. Level 4 data products will be generated late in the EMIT mission lifecycle.

EMIT products have two sources of metadata: embedded NetCDF metadata and the external ECS (generated by the EOSDIS Core System) metadata. The NetCDF metadata contains valuable information including global attributes and dataset specific attributes pertaining to the granule. The ECS .met file is the external metadata file in XML format, which is delivered along with the EMIT product and contains a subset of the NetCDF metadata. The metadata details for each product are provided within their respective user guide located on the DOI landing page.

EMIT data products contain location information in spatially raw format (non-orthocorrected). The location data provided are latitude, longitude, and elevation. The latitude and longitude coordinates are given in ESPG:4326 (World Geodetic System-84) and the longitude values are Easting (increasing eastward from Greenwich). The elevation dataset is estimated at pixel center and sourced from the Shuttle Radar Topography Mission (SRTM v3), which is then resampled to EMIT’s native 60 m spatial resolution.

Learn more about EMIT

Instrument Type

Spectrometers/Radiometers

Instrument Subtype

Imaging Spectrometers/Radiometers

Specifications

Resolution

Spatial

60 m

Spectral

380 – 2500 nm

Related Data Centers/Projects

LP DAAC

NASA's Land Processes Distributed Active Archive Center provides data crucial to the investigation, characterization, and monitoring of biological, geological, hydrological, ecological, and related conditions and processes.

Frequently Asked Questions

Earthdata Forum

Our online forum provides a space for users to browse thousands of FAQs about research needs, data, and data applications. You can also submit new questions for our experts to answer.

Submit Questions to Earthdata Forumand View Expert Responses

Earthdata
Forum