«density current»
۴۷٬۸۸۱ نتیجهA Physically Based Definition of Convectively Generated Density Currents: Detection and Characterization in Convection?Permitting Simulations
In this study, a conceptual model to define convective density currents is proposed. Based on theory, observations and modeling studies, we as 3D coherent structures with an anomalously cold core, adjacent wind gust, vertical structure made of two layers: well-mixed one near the
Observations of Seven Atmospheric Density Current Fronts in Dixon, California*
Seven atmospheric density current fronts are identified in sequences of ground-based, scanning aerosol backscatter lidar images and in situ micrometeorological time series data that were collected simultaneously and nearly continuously between 15 March and 11 June of 2007 in Dixo
Reproducing pyroclastic density current deposits of the 79 CE eruption of the Somma–Vesuvius volcano using the box-model approach
Abstract. We use PyBox, a new numerical implementation of the box-model approach, to reproduce pyroclastic density current (PDC) deposits from Somma–Vesuvius volcano (Italy). Our simplified model assumes inertial flow front dynamics and mass deposition equations axisymmetric cond
Long-runout pyroclastic density currents: Analysis and implications
Abstract Pyroclastic density currents are hazardous, ground-hugging, hot mixtures of gas and solid particles produced by volcanoes. Currents generated the largest explosive eruptions have traveled distances on order 100 km, their devastating impact has repeatedly marked Earth's g
LES validation of lock-exchange density currents interacting with an emergent bluff obstacle
We address the capability of large eddy simulation (LES) to predict physics density currents interacting with bluff obstacles. Most interest in engineering and geophysical applications interact obstacles or topographic features. Validating LES solutions these contexts is crucial
Multi-parametric study of an eruptive phase comprising unrest, major explosions, crater failure, pyroclastic density currents and lava flows: Stromboli volcano, 1 December 2020–30 June 2021
Open conduit volcanoes like Stromboli can display elusive changes in activity before major eruptive events. Starting on December 2020, volcano displayed an increasing activity, that 19 May 2021 led to a crater-rim collapse, with pyroclastic density currents (PDCs) spread along th
Geomagnetic paleointensity in historical pyroclastic density currents: Testing the effects of emplacement temperature and postemplacement alteration
Thellier-type paleointensity experiments were conducted on welded ash matrix or pumice from the 1912 Novarupta (NV) and 1980 Mt. St. Helens (MSH) pyroclastic density currents (PDCs) with the intention of evaluating their suitability for geomagnetic paleointensity studies. PDCs ar
Dynamic pressure evolution within the 18 May 1980 Mount St. Helens pyroclastic density current: evidence from tree damage
Abstract The effects of pyroclastic density currents (PDCs) can be devastating, so understanding their internal dynamics and evolution is important for hazard assessment. We use damaged trees located around Mount St. Helens (USA) as proxy the dynamic pressure ( P dyn ) PDC erupte
Lifting of Ambient Air by Density Currents in Sheared Environments
Two aspects of vorticity associated with cold pools are addressed. First, tilting of horizontal vortex tubes by the updraft at a gust front has been proposed as a means of getting near-ground rotation and hence a tornado. Theory and a numerical simulation are used to show that th
Tracking a Pyroclastic Density Current With Seismic Signals at Mt. Etna (Italy)
Pyroclastic density currents (PDCs) are dangerous flows of volcanic rock and gas that the most deadly proximal volcano hazard. There is significant interest in better understanding PDC dynamics, however, they challenging to study due their extreme hazard, unpredictable occurrence