5 [1] Using the Moderate Resolution Imaging Spectroradiometer (MODIS), Spinning 6 Enhanced Visible and Infrared Imager (SEVIRI), Clouds and the Earth’s Radiant Energy 7 System (CERES) instrument, and BaE146 aircraft data sets, we provide an overview of 8 volcanic ash spatial distribution for six days (4–18 May 2010) and assess their properties 9 and radiative impacts for 17 May primarily over t...

[1] The largest explosive volcanic eruptions that have occurred on Earth generated giant ash clouds from rising plumes that spread in the stratosphere around a height of neutral buoyancy, with estimated supply rates that are in the range 10 to 10 m/s. These giant ash clouds are controlled by a balance between gravity and Coriolis forces, forming spinning bodies of nearly fixed proportions after...

The long duration of the 2010 Eyjajallajökull eruption provided a unique opportunity to measure a widely dispersed volcanic ash cloud. Layers of volcanic ash were observed by the European Aerosol Research Lidar Network with a mean depth of 1.2 km and standard deviation of 0.9 km. In this paper we evaluate the ability of the Met Office’s Numerical Atmospheric-dispersion Modelling Environment (NA...

BACKGROUND In July 1995 the volcano on the West Indian island of Montserrat erupted after being inactive for several hundred years. Since then, clouds of ash have been released intermittently from the volcano. Some of this ash is <10 micro m in diameter and therefore respirable. Concerns were raised that the particles might cause respiratory problems. AIMS To evaluate whether ashfalls had any...

The sub-glacial Eyjafjöll explosive volcanic eruptions of April and May 2010 are analyzed and quantitatively interpreted by using ground-based weather radar data and the Volcanic Ash Radar Retrieval (VARR) technique. The Eyjafjöll eruptions have been continuously monitored by the Keflavík C-band weather radar, located at a distance of about 155 km from the volcano vent. Considering that the Eyj...

Limited observational data exists on the physical interactions between volcanic ash particles and water vapor; yet it is thought that these interactions can strongly impact the microphysical evolution of ash, with implications for its atmospheric lifetime and transport, as well as formation of water and ice clouds. In this study, we investigate for the first time, the hygroscopic properties of ...

Repeated aircraft hazards in Alaska related to volcanic clouds have resulted in the use of a mobile C-band radar devoted to volcanic-cloud monitoring. The radar is located at Kenai, in range of several volcanoes in the Cook Inlet area. Three significant eruptions from the Crater Peak vent of Mount Spurr volcano (about 80 km from Kenai) in 1992 provided the first tests of the radar. The system c...

The aggregation of volcanic ash particles within the eruption column of explosive eruptions has been observed at many volcanoes. It influences the residence time of ash in the atmosphere and the radiative properties of the umbrella cloud. However, the information on the processes leading to aggregate formation are still either lacking or very incomplete. We examine the fate of ash particles thr...

Mount St. Helens volcanic ash was incorporated into a loamy sand greenhouse soil mix to produce concentrations of 0, 0.5, 1.0, 2.0, 4.0, 8.0, 25, 50 and 100% ash. Chemical and physical properties of the various mixtures were determined. Three experiments were conducted in a greenhouse to determine if volcanic ash had any influence on root-knot nematode survival and infectivity. Tomato, Lycopers...