Data dictionary: MARS methane plumes and sources
Easily interpret MARS data.
This data export includes a listing of detected plumes and sources identified by the Methane Alert and Response System (MARS) in CSV format. 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. In this document, we describe the structure of the dataset (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 and source information
The table below summarizes the content of all the sources and plumes detected by MARS (mars_sources_and_plumes.csv). Note that S5P/TROPOMI were generated using Copernicus Atmosphere Monitoring Service information 2025 and NOAA-VIIRS/Sentinel-3 detections are provided by SRON.
| Column name | Definition | Type | Example |
|---|---|---|---|
| name | ID of the source formatted as ISO3CD_S_number*. | String | DZA_S_001 |
| country | Name of the country where the emission occurred. | String | United States of America |
| lat | Latitude coordinate of the source location (north-south direction) in decimal degrees (WGS84), rounded to 5 decimal places .*** | Float | 12.34567 |
| lon | Longitude coordinate of the source location (east-west direction) in decimal degrees (WGS84), rounded to 5 decimal places. *** | Float | 12.34567 |
| location_basin | Name of the basin/region | String | Hassi Messaoud |
| plume_count_since_cutoff | Number of plumes detected on the source after the cutoff date | Interger | 1 |
| cutoff_date_utc | Date from which plumes are shown for the given source | String (datetime) | 2024-01-01T12:00:00 |
| latest_validated_plume_date_local | Local time of latest detection | String (datetime) | 2024-01-01T12:00:00 |
| 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 |
| 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 available": feedback tracking not applicable (non-oil and gas sectors or sources whose last plume was detected before feedback tracking implementation). | String | Yes |
| 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 available": feedback tracking not applicable (non-oil and gas sectors or sources whose last plume was detected before feedback tracking implementation). | String | Yes |
| asset_type | Type of asset. | String | Gas disposal facility |
| plume_id | 36-digit unique identifier (UUID) of the for each plume. | String | bd5f3817-ded2-4cc1-9a5d-a0d02968865f |
| plume_name | Given name of the plume | String | DZA_0003 |
| tile | ID of the satellite product from which the plume was detected. | String | S2B_MSIL1C_20221102T102059_N0400_R065_T31SGR_20221102T122533 |
| tile_date | Timestamp of the satellite observation in ISO 8601 format** | String | 2020-01-01T12:00:00 |
| satellite | Name of the satellite and the agency responsible for the observation. | String | Sentinel-2 - ESA |
| 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. | Interger | 3500 |
| ch4_fluxrate_std | Standard deviation of the estimated methane flux rate, measured in kg/h. Usual range between 200 and 1000 kg/h. | Interger | 400 |
* 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.