Comment on egusphere-2025-3164

<strong class="journal-contentHeaderColor">Abstract.</strong> Volcanic emissions from the Tajogaite volcano, located on the Cumbre Vieja edifice on the island of La Palma (Canary Islands, Spain), caused significant public health and aviation disruptions throughout the volcanic event (19 September &ndash; 13 December 2021, officially declared over on 25 December). The Instituto Geogr&aacute;fico Nacional (IGN), the authority responsible for volcano surveillance in Spain, implemented extensive operational monitoring to track volcanic activity and to provide a robust estimation of the volcanic plume height using a video-surveillance network. In parallel, the State Meteorological Agency of Spain (AEMET), in collaboration with other members of ACTRIS (Aerosol, Clouds, and Trace Gases Research Infrastructure) in Spain, in collaboration with other institutions, carried out an unprecedented instrumental deployment to assess the atmospheric composition impacts of this volcanic event. This effort included a network of aerosol profilers surrounding the volcano. A total of four profiling instruments were installed on La Palma: one MPL-4B lidar and three ceilometers. Additionally, a pre-existing Raman lidar on the island contributed valuable data to this study. In this study, the eruptive process was characterised in terms of the altitude of the dispersive volcanic plume (<em>h_d</em>), measured by both IGN and AEMET-ACTRIS, and the altitude of the eruptive column (<em>h_ec</em>), measured by IGN. Modulating factors such as seismicity and meteorological conditions were also analysed. The consistency between the two independent and complementary datasets (<em>h_d,IGN</em> and <em>h</em>_{<em>d,AEMET</em>}) was assessed throughout the eruption (mean difference of 258.6 m). Our results confirmed the existence of three distinct eruptive phases, encompassing a range of styles from Strombolian explosive to effusive activity. While these phases have been characterised in previous studies, the results of the present work provide complementary information and novel insights from a different scientific perspective, which may be of use in future volcanic crises and will be applied to operational surveillance during such events. A subsequent comparison of <em>h_d,AEMET</em> with the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aerosol layer height product (<em>ALH_CALIOP</em>) revealed a systematic underestimation by the satellite product, with a mean difference of 392.2 m. Finally, the impact of using <em>h_ec</em> in estimating <em>SO</em>₂ emissions from the NASA <em>MSVOLSO2L4</em> satellite-based product was evaluated. When a fixed (standard) plume altitude of 8 km was used instead of the observed <em>h_ec</em>, the total <em>SO</em>₂ mass was significantly underestimated by an average of 56.2 %, and by up to 84.7 %. These findings underscore the importance of accurately determining the volcanic plume height when deriving <em>SO</em>₂ emissions from satellite data.