This is a past event.

Satellite observations of the volcanic plume from the April 2015 eruption of Calbuco volcano, Chile

Calbuco volcano (41.3°S, 72.6°W) is an andesitic volcano in the Chilean Andes and is one of the most active volcanoes in Chile.

On 22nd April, 2015, the volcano erupted for the first time since 1972, in three distinct phases. The first two phases, on 22nd and 23rd April, produced large ash and gas eruption columns, reaching approximately 12 and 15 km respectively. The third phase of the eruption, on 30th April, produced a weak ash column not exceeding 4.5 km.

The monitoring of volcanic plumes, such as those from this eruption, is of critical importance. The impact of volcanic ash on aircraft engines can be catastrophic, requiring rapid analysis of data from satellite instruments to provide accurate input and validation data for dispersion models used by the aviation industry. We were able to monitor the eruption using near real-time observations from the IASI instrument, allowing for dissemination of the location of the plume within 3 hours of measurement by the instrument.

In addition to IASI, the plume was observed by numerous satellite instruments, including OMI, OMPS, MLS, and CALIOP. Data from all of these instruments are analysed and compared allowing for a detailed description of the evolution of the plume over time. The ash plume was visible for 8 days prior to dropping below the detection limit of the IASI instrument. The maximum ash loading measured by IASI was 2.0 Tg in the evening overpass on 23rd April 2015. This measurement included contributions from both the Phase 1 & 2 plumes. A secondary peak of 1.8 Tg was observed following the eruption in Phase 3. The SO2 plume was visible for a lot longer than the ash plume – it was observed by the IASI instrument for 36 days, during which time it had circled the globe. The maximum IASI-derived SO2 atmospheric loading of the plume was 0.3-0.4 Tg over the first two days, following the initial two phases of the eruption. The third phase does not appear to have produced any detectable injection of SO2.

When the SO2 plume reached the west coast of S. Africa, it was caught in a cyclonic system for several days. This system kept the plume in a constrained area and significantly reduced the wind effects on the plume. Since volcanic plumes are usually quickly dispersed over large areas, this rendered an unusual natural ‘laboratory’ to study the chemical conversion of SO2 into H2SO4.

The algorithm development for the H2SO4 retrieval is still a work in progress but current data shows a clear increase in the quantity of sulphate aerosol in the centre of the SO2 plume. Observations of the Antarctic ozone hole over the past 15 years show that the impact of the Calbuco plume was unprecedented (Ivy et al., 2016, doi:10.1002/2016GL071925). The aerosols produced in the plume are believed to have contributed significantly to the record size of the ozone hole in 2015.