The development of near-vent volcanic ash cloud layers due to inhomogeneous atmospheric turbulence and relationship to wind shear

Abstract

Volcanic ash clouds often become multilayered and thin with distance from the vent. We explore one mechanism for development of this layered structure. We review data on the characteristics of turbulence layering in the free atmosphere, as well as examples of observations of layered clouds both near-vent and distally. We then explore and contrast the output of volcanic ash transport and dispersal models with models that explicitly use the observed layered structure of atmospheric turbulence. The results suggest that the alternation of turbulent and quiescent atmospheric layers provides one mechanism for development of multilayered ash clouds by modulating the manner in which settling occurs.