Optical and Microphysical Properties of the Hunga-Tonga Stratospheric Aerosol Plume derived from Lidar and In Situ Measurements at Reunion Island (21°S, 55°E)
Résumé
The highly-explosive eruption of the Hunga-Tonga Hunha Ha’apai volcano, that occurred on 15 Jan. in the South Pacific, was associated with a powerful blast that injected gases, steam and aerosols to unprecedentedly high altitudes. The Tonga Rapid Response Experiment (TR²Ex) was triggered few days after in La Réunion island (21°S, 55°E), directly downwind of the eruptive plume. Two lidars, operating at 355 nm and 532 nm, sampled the overflying plume every night from 19 Jan. until 28 Jan. During the same period, more than 15 balloons have been launched to perform in situ measurements of the stratospheric plume. These observations involved ozone, water vapor, aerosol size distribution and SO2 sondes. These efforts allowed to assess both the vertical structure, the optical and microphysical properties of the aerosol stratospheric burden. In particular, a wide plume altitude range from 36 km down to 18 km has been highlighted along time, with heterogeneous aerosol optical depth that reached 0.84 at 532 nm and Angström exponents from -0.8 to 1.2. Such temporal evolution is related to both the injection heights of the volcanic material and the stratospheric dynamic and chemistry. Findings resulting from the synergistic use of the TR²Ex dataset will be presented and discussed.