On Saturday, January 15, 2022 the volcano "Hunga Tonga Hunga Ha‘apai" on the island state of Tonga erupted in a powerful explosion at around 5:15 Central European Time. Enormous amounts of sulphur dioxide (SO2), almost 0.4 Mt, were ejected in the process and distributed over a large part of the atmosphere. Since that time the Sentinel-5P (S5P) measurements operationally processed at EOC continue recording the subsequent volcanic emissions.
The cloud, currently ca. 7,000,000 square kilometres in area, was carried primarily westward over the Pacific Ocean toward Australia and now covers half of that continent at an elevation of ca. 20 km.
The caustic gas threatens not only the environment and the population located near the volcano. It also endangers the passengers of commercial aircraft should it find its way into the airplane cabin. Aircraft engines can also be damaged. Timely identification and recording of SO2 helps to minimize these risks and points out where dangerous gas and ash concentrations canbe expected. So far, island flights are being continued.
Shortly after the first eruption, the TROPOMI sensor on S5P supplied the first measurements of SO2 concentration over the island, and they are being continuously analysed ever since. The UVN spectrometer TROPOMI has a spatial resolution of 3.5 × 5.5 kilometres and measures other trace gases in the atmosphere in addition to SO2, such as ozone and nitrogen dioxide, daily and worldwide.
EOC‘s INPULS project analyses these data, generates various products based on Sentinel-5P data, and makes them available to the public at large.