"Below, we outline how implementing Sentinel-3 satellites helps users gain more accurate and timely satellite data that can be used to mitigate atmospheric methane pollution around the globe."
In a recent article, we covered how the TROPOspheric Monitoring Instrument (TROPOMI) is used to monitor global methane emissions from space. The TROPOMI is the world's most expansive methane monitoring detection system, but until now, it has been challenged to identify and monitor methane emissions and leaks with real-time accuracy.
However, thanks to a new tiered approach, the methane monitoring system has gained even more accuracy and can identify methane leaks much faster than before.
The missing link? The Sentinel-3 satellite mission - part of a satellite collective in ESA’s Copernicus program that provides satellite data to users worldwide.
Below, we outline how implementing Sentinel-3 satellites helps users gain more accurate and timely satellite data that can be used to mitigate atmospheric methane pollution around the globe.
The Previous Approach: Sentinel-5 and Sentinel-2
Before implementing Sentinel-3 into the newly improved tiered methane monitoring system, researchers only utilized the Sentinel-5 and Sentinel-2 satellites.
Since 2017, the Sentinel-5 precursor satellite has been monitoring methane emissions from space. In the beginning, the Sentinel-5 was solely equipped with the TROPOspheric Monitoring Instrument (Tropomi), which uses medium-resolution observations to pinpoint potential methane hotspots around the globe.
While this instrument is particularly useful, as it can monitor wide ranges of land on Earth, it does not have the high-resolution capabilities needed to pinpoint the exact sources of methane emissions in great detail. Still, the first 5 years of reporting had staggeringly useful results, which were typically followed up with high-resolution observations carried out by the Sentinel-2 satellite.
Since the Sentinel-5 satellite observations were made with medium-resolution capabilities, Sentinel-2 was typically tasked with follow-up observations using high-resolution imagery. These high-resolution capabilities made it easier to detect some of the most significant methane leaks in every application and landscape, from landfills to deserts.
Sentinel-2 provides high-resolution observations with near-global coverage, making global observations every 5 days, more or less. These observations helped end-users with decision-making for applications like land use management, risk management, land cover classification, and more.
The tip-and-cue approach between Sentinel-5 and Sentinel-2 allowed for detecting and monitoring methane leaks but still needed timely reference data for more useful mitigation techniques.
That’s where Sentinel-3 is solving some of the biggest pain points.
Sentinel-3: Providing More Timely and Accurate Methane Detection
As described above, solely using the Sentinel-5 and Sentinel-2 satellites for methane detection and monitoring has its drawbacks, the biggest being daily monitoring of potential and existing methane leaks. However, implementing Sentinel-3 into the existing tiered approach to monitoring methane leaks and emissions allows for a much faster and more accurate overview of global methane emissions.
Researchers in the Netherlands published a paper describing how using Sentinel-3 in a top-down tiered approach minimizes the time between methane observations and can provide a much clearer outlook into potential methane leaks.
Since the Sentinel-2 satellite only makes observations at any point on the globe every 5 days, the delays can be quite impactful. This means that short-term methane leaks (blowouts) can go unnoticed, leaving those who can mitigate them in the dark when it matters most.
However, using Sentinel-3, which has daily coverage capabilities, greatly reduces the time between observations, making it possible for those on the ground to respond to problems before they get out of hand.
While Sentinel-3 does not have the same high-resolution capabilities as the Sentinel-2, the revisit rate helps users identify problems that can be followed up with the Sentinel-2 when the next pass is available. Again, this is particularly useful for short-term methane leaks and/or blowouts that could go unnoticed without using Sentinel-3.
Sentinel-3 Case Study: Methane Plumes in Algeria
Below, we walk through a methane plume case study in Algeria using the Sentinel-5, Sentinel-3, and Sentinel-2 missions.
On January 4, 2020, a methane plume in Algeria was detected by Sentinel-5 in the Hassi Messaoud Oil and Gas Field. To identify the origin of the plume detected by Sentinel-5, Sentinel-3 and Sentinel-2 were used to gather more information.
Sentinel-3 observed the scene first, locating the source facility of the plume, containing multiple possibilities for the exact source (flare pits, oil/gas wells, etc.).
Sentinel 2 followed up the observation with a more detailed approach - detecting plumes from a single oil & gas well and revealing the source of the original plume caught by Sentinel-5.
The above case shows how all three satellites can be used to detect the exact source of methane emissions without the latency between observations that would come with solely using the Sentinel-5 and Sentinel-2.