Estimates of plume height from infrasound for regional volcano monitoring

Present efforts in volcano monitoring, particularly in Southeast Asia, rely on the combination of local data (generally gathered at less than 100 km from the volcano), and satellite remote sensing. While this combination has its strengths, there are still weaknesses that the use of ground-based remote sensing data - such as distant infrasound measurements - could help alleviate. Infrasound offers tools for detecting and characterizing volcanic plumes independent of cloud cover and time of day. Larger volcanic eruptions generate infrasound that is related to the plume and offers a unique view into eruption dynamics within the context of monitoring. Past research has demonstrated that infrasound can be used to estimate source parameters, such as the rate at which material is ejected from volcanic vents during eruptions; these are key input parameters into empirical and numerical models to estimate the height of volcanic plumes, atmospheric ash transport and dispersion. Here, we demonstrate the use of remote infrasound in estimating the height of volcanic plumes, including a case study on the May 30, 2014 plume from the volcano Sangeang Api in Indonesia. We were able to determine the plume height using infrasound gathered from 2000 to over 5000 km distance from the volcano. During the January 2020 eruption of Taal volcano in the Philippines, this method was applied to remote infrasound recorded 1650 km to the east. We show that our workflow can be implemented in near real-time, offering an effective tool for rapid plume height measurement, including associated uncertainties, when volcanic clouds are not visible from the ground or space

Toward an improved representation of middle atmospheric dynamics thanks to the ARISE project

This paper reviews recent progress toward understanding the dynamics of the middle atmosphere in the framework of the Atmospheric Dynamics Research InfraStructure in Europe (ARISE) initiative. The middle atmosphere, integrating the stratosphere and mesosphere, is a crucial region which influences tropospheric weather and climate. Enhancing the understanding of middle atmosphere dynamics requires improved measurement of the propagation and breaking of planetary and gravity waves originating in the lowest levels of the atmosphere. Inter-comparison studies have shown large discrepancies between observations and models, especially during unresolved disturbances such as sudden stratospheric warmings for which model accuracy is poorer due to a lack of observational constraints. Correctly predicting the variability of the middle atmosphere can lead to improvements in tropospheric weather forecasts on timescales of weeks to season. The ARISE project integrates different station networks providing observations from ground to the lower thermosphere, including the infrasound system developed for the Comprehensive Nuclear-Test-Ban Treaty verification, the Lidar Network for the Detection of Atmospheric Composition Change, complementary meteor radars, wind radiometers, ionospheric sounders and satellites. This paper presents several examples which show how multi-instrument observations can provide a better description of the vertical dynamics structure of the middle atmosphere, especially during large disturbances such as gravity waves activity and stratospheric warming events. The paper then demonstrates the interest of ARISE data in data assimilation for weather forecasting and re-analyzes the determination of dynamics evolution with climate change and the monitoring of atmospheric extreme events which have an atmospheric signature, such as thunderstorms or volcanic eruptions

Infrasound monitoring for atmospheric studies : challenges in middle atmosphere dynamics and societal benefits

Violent volcanic eruptions, common especially in Southeast Asia, pose an ongoing serious threat to aviation and local communities. However, the physical conditions at the eruptive vent are difficult to estimate. In order to tackle this problem, satellite imagery and infrasound can rapidly provide information about strong eruptions of volcanoes not closely monitored by on-site instruments. For example, the recent infrasonic array at Singapore, installed to support the coverage of the International Monitoring System, allows identification of nearby erupting volcanoes based on the characteristics of the recorded signal. But, due to its location close to the equator, seasonal changes in the wind velocity structure of the atmosphere strongly affect its potential to detect small volcanic eruptions at certain azimuths. To overcome this limit, infrasound could be augmented with satellite data. Yet, with the high average cloud cover in Southeast Asia, there are also challenges to identify weak volcanic plumes using satellite based monitoring techniques. In this chapter, we aim to examine the relative strengths and weaknesses of the two technologies to better understand the possibility to improve overall detection capability by combining infrasound with satellite imagery

Reconstruction of the 2018 tsunamigenic flank collapse and eruptive activity at Anak Krakatau based on eyewitness reports, seismo-acoustic and satellite observations

International audienc