New SkyTruth Alerts layer helps pollution trackers quantify flaring trends.
Those tracking methane flaring will want to try the newest layer in SkyTruth Alerts: a summary of monthly flaring activity that can be based on your current map view or selected Areas of Interest (AOIs). The source of this layer is the VIIRS Nightfire data produced by the Earth Observation Group (EOG) at the Colorado School of Mines.
Here is an example showing the Permian basin in Alerts and the statistics that can be produced for the AOI:
Although the new layer can help quantify trends in flaring, the data probably will not represent a complete dataset of flaring because clouds can block the satellite’s ability to detect some flaring events. Far less frequently, solar flaring or satellite outages can also disrupt detection. And if the flaring at a particular location is intermittent, the satellite could be passing overhead at a moment when the flare is inactive.
Furthermore, upgrades to the VIIRS Nightfire algorithm might make comparisons between certain time periods less valid. For example, in December 2017 the algorithm made use of a new band of information, or wavelength interval on the electromagnetic spectrum, available from the satellite. The additional data enhanced the ability to detect flaring events, which gave the false impression that flaring activity worldwide suddenly increased.
About the data
You can read more about VIIRS Nightfire data on EOG’s website. The fields you’ll find in Alerts are all calculated using EOG’s Nightfire algorithm, as described in this paper. Monthly summaries are available in Alerts starting with March, 2012. The summaries include:
- Temperature: Same as EOG’s Temp_BB which EOG describes as, “IR-source temperature assuming blackbody source (Kelvin degrees).”
- Radiant Output: Same as EOG’s RHI which EOG describes as, “IR-source radiant heat intensity (Units in W/m2).”
- Radiative Heat: Same as EOG’s RH which EOG describes as, “IR-source radiant heat (Units in MW).”
- Footprint: Same as EOG’s Area_BB which EOG describes as, “Area of IR-source assuming blackbody source (Units in m2).”
The data is further categorized by the range of flare temperatures. EOG scientists report that the majority of gas flares fall in the range of 1500 to 2000 Kelvin; biomass burning, industrial sites and volcanoes fall in the 600 to 1300 Kelvin range; and 1300 to 1500 Kelvin is a crossover zone between gas flares and biomass burning. (See a discussion in this paper.)
How to access this layer
The SkyTruth Alerts map can be found at alerts.skytruth.org. Anyone can move around the map, navigate to their AOIs, and zoom in and out, all while viewing the most recent environmental incidents for the currently displayed map. To view the new Monthly Flaring Summary layer, you’ll need to register for an account (it’s free!) and login.
Once you’ve logged into Alerts, access the data by following these steps:
- Navigate to the area you’re interested in by zooming in and out and click-dragging the map.
- Click “Layers” in the left sidebar.
- Click “Flaring Summary” under the “Oil & Gas” group. You may need to first click “Oil & Gas” to see these layers.
- Complete the start and end months and click Submit.
- Once you’ve brought up the summary data, a button will appear that allows you to download a CSV file of the data.
- If you have already selected an AOI (skytruth.org/section/manage-areas-of-interest), then the numbers shown will reflect those boundaries. Otherwise, the data will correspond to the full area shown on your screen.
If you find this layer – or any of the layers inside of Alerts – useful, please send us a note at firstname.lastname@example.org to let us know you’re using it. SkyTruth Alerts can be a great tool for monitoring the environment. We have been most successful when the features we add are driven by requests from those who use the application. So don’t be shy! Tell us what works, what doesn’t work, what features you’d like to see added, and especially, any successes you’ve had using Alerts!