Instrument

Element Description

The instrument elements enable the specification of instruments used to collect the data available in the dataset. Instruments provided in CMR metadata must be chosen from a controlled keyword hierarchy maintained in the Keyword Management System (KMS). A list of valid instrument keywords can be found here: https://gcmdservices.gsfc.nasa.gov/static/kms/instruments/instruments.csv?

Optionally, attributes specific to the instrument (such as swath width, revisit period, spectral range, etc.) may be specified in the characteristics elements. Please see the Characteristics wiki page for a detailed description of the characteristics sub-elements. 

Best Practices

Instrument keywords are important for the discovery of data. All relevant instruments should be listed for each dataset, and each instrument listed should be provided under its associated platform. It is preferred that more specific instrument keyword terms be chosen from the KMS when available. For example, if data were collected from the AMSR-E instrument, it is preferred that "AMSR-E" be listed as the instrument as opposed to the more generic "RADIOMETERS" keyword. If a particular instrument keyword is missing from the KMS, it is possible to put in a request to have it added. The KMS is managed by the Global Change Master Directory (GCMD) and new keyword requests may be made through the GCMD Keywords Community Forum.

In the KMS, there is a hierarchy for instrument keywords. Instrument keywords should be provided in the metadata field corresponding to the appropriate position of the keyword hierarchy, otherwise the keyword will be rendered invalid. For example, the instrument short name specified in the KMS should not be provided in the instrument 'long name' field in the metadata. When listing instruments, an instrument short name will always be required. While instrument long names are not required, it is highly encouraged that long names be provided if one is listed in the KMS. Many instrumentshort names are comprised of acronyms, so inclusion of the long name provides additional context to a user who may not be familiar with the acronym. Instrument keywords are not case sensitive.

A minimum of one instrument must be listed under each platform. Multiple instruments may be listed under a single platform if appropriate. Platform/instrument relationships are not currently validated within the KMS, so care should be taken to ensure that the correct instrument is listed under the correct platform.

It is recommended that instrument keywords be assigned in a consistent manner. For example, if data for several collections were collected by the "SMAP L-Band Radiometer" instrument, it is recommended that the metadata for all of those collections list "SMAP L-Band Radiometer" as the instrument short name. Providing "SMAP L-Band Radiometer" as the instrument in some records, but the more generic "RADIOMETERS" as the instrument in other records, results in an inconsistent experience for a user discovering data. This is especially true for users narrowing down their search results in the Earthdata Search client by using the faceted search options. 

In the case that it does not make sense to provide an instrument for a dataset, "Not Applicable" is an accepted value.     

The Instruments/Technique field is optional. It can be used to further describe the technique utilized by the instrument for data collection. For example, the technique for a laser altimeter instrument on board a satellite could read "Measures the distance of the satellite from the Earth's surface by taking a precise measurement of the time it takes a transmitted laser pulse to hit the ground and then return to the instrument." 

The Instruments/NumberOfInstruments field is optional. It can be used to indicate the number of instruments (i.e. sensors) used on the instrument while acquiring data. For example, the Terra satellite carries the ASTER instrument. The ASTER instrument is made up of 3 instrument subsystems (VNIR, SWIR, and TIR). In this example, the Instruments/NumberOfInstruments field would read "3".

The Instruments/OperationalModes field is optional and may be repeated. This field can be used to specify the mode(s) in which an instrument collects data. For example, the Sentinel-1 satellite collects data in four different modes. If a collection were to contain data acquired in all four modes, the OperationalModes field could be repeated four times and read "Stripmap (SM)", "Interferomic Wide swath (IW)", "Extra-Wide swath (EW)", "Wave (WV)"  

Examples (ShortName > LongName):

SMMR > Scanning Multichannel Microwave Radiometer

OLI > Operational Land Imager

UAVSAR > Uninhabited Aerial Vehicle Synthetic Aperture Radar

LIS > Lightning Imaging Sensor

XPOL > NOAA/ETL X-band Polarimetric Doppler Radar 

Value needed for translations:

The following value is needed by the CMR to translate older non UMM compliant records to and from the UMM and other supported specifications where non required elements are considered required but no valid is given.  This is needed partly because the CMR still allows a non UMM compliant record to be ingested with warnings.

UNDEFINED  - DIF 10 records found to be missing instruments by software will be automatically assigned a value of "Not Provided". It should then be confirmed whether an instrument can be assigned or whether "Not Applicable" should be provided. The value "Not Provided" should not be used by metadata providers. 

Metadata Validation and QA/QC

All metadata entering the CMR goes through the below process to ensure metadata quality requirements are met. All records undergo CMR validation before entering the system. The process of QA/QC is slightly different for NASA and non-NASA data providers. Non-NASA providers include interagency and international data providers and are referred to as the International Directory Network (IDN).

Please see the expandable sections below for flowchart details.

Dialect Mappings

UMM Migration

None

Future Mappings

Platforms: [
  {
    Type: "Earth Observation Satellites",
    ShortName: "Aqua",
    LongName: "Earth Observing System, Aqua",
    Instruments: [
      {
        ShortName: "MODIS",
        LongName: "Moderate-Resolution Imaging Spectroradiometer",  
        Characteristics: [
          {
            Name: "SwathWidth",
            Description: "The width of the sensor scan as the satellite moves along the ground track.",
            DataType: "INT",
            Unit: "Kilometers",
            Value: "2330",
          }
        ]
      }
    ]
  }
],

History

UMM Versioning

ARC Documentation