The highly-explosive eruption of the Hunga-Tonga Hunga Ha’apai volcano (HTHH), 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. Here we present unique observations of the young volcanic aerosol plumes by ground-based lidars at La Reunion island (21°S, 55°E), located directly downwind of the eruption. Two lidars, operating at 355 nm and 532 nm, sampled the overflying plume every nights from 19 Jan. until 28 Jan. We assess both the vertical structure and the optical properties. 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.
