The primary data used by the Gas Flare Tracker to locate and quantify gas flares is periodically updated from the Visible Infrared Imaging Radiometer Suite (VIIRS) on board the Suomi National Polar-orbiting Partnership (S-NPP) satellite. All subsequent calculations and figures displayed are based on this measurement. It is assumed that all flares are buring permanently to come to the figures calculated and presented in the application.
The primary data used by the Gas Flare Tracker to locate and quantify gas flares is periodically updated from the Visible Infrared Imaging Radiometer Suite (VIIRS) on board the Suomi National Polar-orbiting Partnership (S-NPP) satellite. This takes nightly geo-located snapshots of flames burning over a certain intensity and this data is made freely available by the US National Oceanic and Atmospheric Administration (NOAA).
The VIIRS cannot take accurate measurements when there is cloud cover which is most of the year in the Niger Delta and therefore the raw data available is a partially complete picture.
[Technical notes: The satellite measures several light frequencies and then tries to reconstruct the emission curve (Planck curve) of the object. Some frequencies are picked up and others not, some times because some frequencies are blocked by clouds or other disturbances. They might be picked up, but attenuated. Their analysis estimates the quality of the measurement in each frequency and computes a score. It then tries to fit them into the ideal emission curve, and if the fit is good enough it can compute the temperature of the object that emitted those frequencies. If the curve fit is not possible, they can't compute a temperature.]
Using the VIIRS data around 200-300 onshore and offshore gas flare sites have been identified in the Niger Delta (some burning multiple flares in close proximity). Between 100 and 600 flames are detected in the region on most nights by VIIRS however due to atmospheric interference very few measurements are ususally able to be safely/accurately made. The VIIRS does not estimate measurements unless it is sure it can do this reliably and therefore it discards a vast majority of its own readings.
It should also be noted that gas flares from crude oil wells do not necessarily burn continuously. A break in the extraction of oil will result in a break in associated gas flaring. Oil wells do not necessarily pump oil continuously which is another reason that gas flares are not always picked up in the nightly satellite flyover.
The Gas Flare Tracker ‘robot’ periodically filters through the VIIRS dataset isolating flames detected within the Niger Delta region and putting them on the Gas Flare Tracker map.
These measurements are then grouped with other measurements of flames that the satellite has picked up in the same proximity.
Through cross-referencing the grouped VIIRS data with google earth satellite view and available information on oil wells, gas flaring sites are then identified.
The Gas Flare Tracker pulls-in, filters and displays records of flames that the VIIRS has been able to measure based on its own assumptions and processing alogorithms since March 2013 to the present day. When it can get a clear reading the VIIRS esimates temperature and volume of methane equivalent from the flames it pickes up.
In order to increase trust in the estimations displayed the system only includes measurements taken that are deemed 'confidently clear' of cloud cover.
Once the system has imported the multiple incidences of flames and associated measurements the following process occurs: