Global Monitoring of Volcanic SO2 Degassing Using Sentinel-5 Precursor Tropomi.

We present here the TROPOMI SO 2 product, which is publicly available since April 2018. We describe the capabilities and limitations of the product for the monitoring of volcanic SO 2 degassing. With several examples, we illustrate the benefit of a small satellite pixel of 3.5 x 5.5 km2. Owing to its improved detection limit, the data can be used to generate time series of SO 2 mass over number of volcanoes, with a large range of SO 2 emissions. We use Nyiragongo as a show case and correlate the SO 2 mass data with lava lake level estimates and local measurements of the seismicity. This paper also presents on-going developments to further improve the performance of the product for weak SO 2 loadings using a new algorithm, COBRA.