Data dictionary: MARS methane plumes and sources
Easily interpret MARS data.
IMEO built the Eye on Methane data platform to drive climate action. We invite you to use this data to identify and mitigate methane emissions.
This data export includes two data sets: one listing detected plumes and one listing detected sources identified by the Methane Alert and Response System (MARS). Files are available in either CSV or GeoJSON format, depending on the option selected on the website. A plume is a single methane emission observation from one satellite overpass, while a source is a ground location where one or more plumes have been detected over time. The tables below describe the structure of both datasets (plumes and sources), including each variable’s name, definition, data type and an example value.
If you need more detail about how the data is produced or how to interpret it, several resources are available. The UNEP IMEO Technical Documentation for Methane Satellite Detection and Quantification provides a detailed explanation of the methodology. Our Frequently asked questions section addresses common issues. You can also contact the MARS team at unep-mars@un.org if you require further clarification.
All plumes on Eye on Methane // GLOBAL detected by Sentinel-2, Landsat-8/9, EMIT, PRISMA and EnMAP were requantified after 20 February 2026. For more information on the quantification methodology, see the UNEP IMEO Technical Documentation for Methane Satellite Detection and Quantification.
The data may not be used for any commercial purposes and is shared under a Creative Commons BY-NC-SA 4.0 (“Attribution-NonCommercial-ShareAlike 4.0 International") license. This means that you are free to share and adapt the material, if you credit UNEP’s International Methane Emissions Observatory and indicate whether any changes were made.
Per-plume information
The table below summarizes the content of all the plumes detected by MARS (unep_methanedata_detected_plumes). Note that S5P/TROPOMI plumes with detection institution CAMS/ECMWF/SRON were generated using Copernicus Atmosphere Monitoring Service information 2025.
| Column name | Definition | Type | Example |
|---|---|---|---|
| id_plume | Unique 36-character identification code of each plume. | String (text) | bd5f3817-ded2- 4cc1-9a5da0d02968865f |
| source_name | ID of the source, formatted as {ISO3CD}_S_{number}.* | String | ALG_S_002 |
| satellite | Name of the satellite and the agency responsible for the observation. | String | Sentinel-2 - ESA |
| tile_date | Timestamp of the satellite observation in ISO 8601 format.** | String | 2020-01- 01T12:00:00 |
| tile_background | ID of the satellite product used as the background (reference) for the multi-temporal retrieval. | String | S2B_MSIL1C_20221102T102059_N0400_R065_T31SGR_20221102T122533 |
| lat | Latitude coordinate of the source location (north-south direction) in decimal degrees (WGS84), rounded to five decimal places .*** | Float | 12.34567 |
| lon | Longitude coordinate of the source location (east-west direction) in decimal degrees (WGS84), rounded to five decimal places. *** | Float | 12.34567 |
| actionable | • “Yes”: if the plume is 1) high resolution, 2) from the oil and gas sector, 3) attributable to a facility, and 4) validated by MARS remote sensing experts within approximately 15 days from image acquisition. • “No”: if the (high-resolution and from the oil and gas sector) plume is not attributable to a facility and/or is not validated by MARS remote sensing experts within approximately 15 days from image acquisition. • “Not applicable”: if the plume is not from the oil and gas sector and/or is not from not high-resolution satellites. • “Not available”: for plumes whose validation date is not available (i.e. for plumes detected before May 2024). | String | YES |
| notified | • TRUE indicates whether the plume was notified to governments and/or OGMP 2.0 companies (if applicable). • FALSE indicates that the plume was not notified because it was not ‘actionable’ or it was detected during the pilot phase. | Boolean | TRUE |
| country | Name of the country where the emission occurred. | String | United States of America |
| sector | Industry sector of the emission source (e.g., ‘Oil and Gas’, ‘Waste’, ‘Met Coal’, ’Thermal Coal', ‘Thermal and Met Coal’ or ‘Other’). | String | Oil and gas |
| detection_institution | Name of the institution responsible for detecting the emission (e.g., CarbonMapper, Kayrros, NASA JPL EMIT, UNEP IMEO MARS and UPV LARS). | String | UNEP IMEO MARS |
| quantification_institution | Name of the institution responsible for quantifying the emission. | String | UNEP IMEO MARS |
| tile | ID of the satellite product from which the plume was detected. | String | S2B_MSIL1C_20221102T102059_N0400_R065_T31SGR_20221102T122533 |
| ch4_fluxrate | The methane flux rate is a measure of the rate at which methane gas (CH₄) is emitted from a specific source into the atmosphere over time. It quantifies the mass of methane released by unit of time in kilograms per hour (kg/h). MARS provides an estimate of this flux, with typical emissions detectable by satellites ranging from 500 to 10,000 kg/h. | Integer | 3500 |
| ch4_fluxrate_std | Standard deviation of the estimated methane flux rate, measured in kg/h. Usual range between 200 and 1000 kg/h. | Integer | 400 |
| wind_u | Eastward component of wind speed, measured in m/s. | Float | 1.00 |
| wind_v | Northward component of wind speed, measured in m/s. | Float | 1.00 |
| total_emission | Total mass of methane attributable to the emission, in tonnes. Only available for estimates made with a combination of VIIRS and Sentinel-3/GOES/TROPOMI. | Integer | 100 |
| total_emission_std | Standard deviation of the total estimate methane mass, in tonnes. Only available for estimates made with a combination of VIIRs and Sentinel-3/ GOES/TROPOMI. | Integer | 10 |
| wind_speed | Magnitude of the windspeed, measured in m/s. | Float | 1.00 |
| last_update | Timestamp of the most recent modification to the plume entry, in ISO 8601 format. | String | 2020-01- 01T12:00:00.00000 0 |
| insert_date | Timestamp of when the plume was recorded in the database, in ISO 8601 format. | String | 2020-01- 01T12:00:00.00000 0 |
Per-source information
The table below summarizes the content of all the sources with emissions detected by MARS (unep_methanedata_detected_sources).
| Column name | Definition | Type | Example |
|---|---|---|---|
| source_name | ID of the source, formatted as {ISO3CD}_S_{number}*. | String | ALG_S_002 |
| lon | Longitude coordinate of the source location (east-west direction) in decimal degrees (WGS84), rounded to 5 decimal places. *** | Float | 12.34567 |
| lat | Latitude coordinate of the source location (north-south direction) in decimal degrees (WGS84), rounded to 5 decimal places. *** | Float | 12.34567 |
| country | Name of the country where the source is located | String | United States of America |
| sector | Industry sector of the emission source (e.g., ‘Oil and Gas’, ‘Waste’, ‘Met Coal’, ’Thermal Cola’, ‘Thermal and Met Coal’ or ‘Other’). | String | Oil and Gas |
| persistency | Estimates how often emissions are detected from a specific source over time. It looks at the number of times emissions were detected compared to the number of high-quality observations over the last six months. Values range between 0 and 1, or null if insufficient observations are available. | Float or Null | 0.65 |
| persistency_std | Standard deviation of the persistency estimate. Values range between 0 and 1, or null if insufficient observations are available. | Float or Null | 0.1 |
| persistency_category | Categorical classification of emission frequency based on persistency:Undetermined": insufficient observations.“absent": no emissions detected, persistency is equal to 0. "sporadic": persistency within the interval (0, 0.2]. "frequent": persistency within the interval (0.2, 0.8]. "persistent": persistency larger than 0.80. | String | frequent |
| n_plumes_detected | Number of plumes attributed to this source from all the available observations. | Integer | 12 |
| id_last_plume | 36-digit unique identifier (UUID) of the latest plume detected. | String | a3f2e1d4-5c6b-7a8e-9f0d-1c2b3a4e5f6g |
| last_plume_date | Timestamp of the satellite observation in ISO 8601 format** | String (datetime) | 2020-01-01T12:00:00 |
| feedback_operator | Indicates whether feedback has been received from the facility operator regarding any emission from this source: • "Yes": feedback received. • "No": no feedback received (only for Oil and Gas sector sources with plumes after feedback tracking began). • "Not Applicable": feedback tracking not applicable (non-Oil and Gas sectors or sources whose last plume was detected before feedback tracking implementation). | String | Yes |
| feedback_government | Indicates whether feedback has been received from the relevant government authority regarding any emission from this source: • "Yes": feedback received. • "No": no feedback received (only for Oil and Gas sector sources with plumes after feedback tracking began). • "Not Applicable": feedback tracking not applicable (non-Oil and Gas sectors or sources whose last plume was detected before feedback tracking implementation). | String | Yes |
| feedback | Combined feedback status from both operator and government: • "Yes": feedback received from either operator or government (or both). • "No": no feedback received from either operator or government. • "Not Applicable": feedback tracking not applicable (non-Oil and Gas sectors or sources whose last plume was detected before feedback tracking implementation). | String | Yes |
| notified | Indicates whether a notification has been sent to the relevant government or facility operator: • “Yes”: At least one plume over this source has been notified. • “No”: No plumes on this source have been notified. • “Not Applicable”: MARS currently only notifies Oil and Gas sources. | String | Yes |
| source_type | Equipment, infrastructure or facility associated with source of methane emission. Source types with the suffix "generic" indicate that the specific emitting equipment could not be identified from the available information. | String | Flare |
* ISO3CD refers to the three-letter codes defined in ISO 3166-1 and the number is the 3-digit identification number.
** The timestamp of satellite observation in ISO 8601 format, which refers to a standardized way of representing the exact date and time when the observation occurred. The time zone is UTC.
*** The source coordinates for Sentinel-5P are approximate and automatically generated based on plume mask and the wind direction.