Daily detection and quantification of methane leaks using Sentinel-3: a tiered satellite observation approach with Sentinel-2 and Sentinel-5p

The twin Sentinel-3 satellites have multi-band radiometers which observe at methane-sensitive shortwave infrared bands with daily global coverage and 500 m ground pixel resolution. Here, we investigate the methane observation capability of Sentinel-3 and how its coverage-resolution combination fits between Sentinel-5p and Sentinel-2. Sentinel-5p measures methane with high precision and daily global coverage allowing worldwide leak detection, but it has a coarse spatial resolution of 7 × 5.5 km2. The Sentinel-2 twin satellites have multi-band instruments that can identify source locations of major leaks (> 1 t/hr) with their methane observations of 20 m resolution under favorable observational conditions, but these satellites lack daily global coverage. We show that methane plume enhancements can be retrieved from the shortwave infrared bands of Sentinel-3. We report a lowest emission detection by Sentinel-3 of 9 t/hr under favorable detection conditions of low wind speeds and high surface albedo. We demonstrate Sentinel-3’s identification and monitoring of methane leaks using two case studies. Near Moscow, Sentinel-3 shows that two major short-term leaks separated by 30 km occurred simultaneously at a gas pipeline and appear as a single methane plume in Sentinel-5p data. For a major Sentinel-5p leak detection near the Hassi Messaoud oil/gas field in Algeria, Sentinel-3 identifies the leaking facility emitting continuously for 6 days, andSentinel-2 pinpoints the source of the leak at an oil/gas well. Sentinel-2 and Sentinel-3 also show the 6-day leak was followed by a four-month period of burning of the leaking gas, suggesting a gas well blowout to be the cause of the leak. We find similar source rate quantifications from plume detections by Sentinel-3 and Sentinel-2 for these leaks, demonstrating Sentinel-3’s utility for emission quantification. These case studies show that zooming in with Sentinel-3 and Sentinel-2 in synergy allows precise identification and quantification as well as monitoring of the sources corresponding to methane anomalies observed in Sentinel-5p’s global scans.