Ascent dynamics of large phreatomagmatic eruption clouds: The role of microphysics

摘要: [1] We examine the impact of abundant surface water interaction on development volcanic clouds from large-scale (>108 kg s−1 magma) phreatomagmatic eruptions, presenting first 2-D large-eddy simulations “wet” plumes that incorporate effects microphysics. The Active Tracer High-Resolution Atmospheric Model was forced with field-derived inputs an exceptionally large eruption: 27 ka Oruanui supereruption (Taupo volcano, New Zealand). Surface contents were varied 0 to 40 wt% for eruptions equivalent magma eruption rates ∼1.3 × 108 and 1.1 109 s−1. Our findings confirm increased has a pronounced column stability, leading transitional behavior hybrid resulting simultaneous ascent material stable columns pyroclastic density currents (PDCs). Contrary suggestion previous workers, however, does not systematically lower spreading level or maximum height clouds, owing vigorous microphysics-assisted lofting PDCs. simulated ash cloud dimensions provide close match field evidence case study. Cloud heights collapsing also show notable sensitivity changes in altitude tropopause, while ambient humidity primarily impacts abundance airborne hydrometeors (particularly ice) associated clouds. General relationships between style, meteorological conditions, vertical profiles emissions outlined here could be adapted use operational forecasting deposit reconstruction techniques already existence.