Distribution and description of volcanic eruptive products

Volcanic ash and sulphur dioxide may impact climate. Reliable methods for monitoring atmospheric volcanic ash and sulphur dioxide amounts are therefore needed. Within this project the aim is to improve volcanic ash and sulphur dioxide detection by infrared satellite measurements, and to develop methods to derive three-dimensional volcanic plume structure from multispectral ground based IR cameras. Part of this work is carried out together with partners from the EC-funded FUTUREVOLC project (http://futurevolc.hi.is/) in which NILU is leading work package 8. To improve volcanic ash detection a novel study has been made in which the volcanic ash infrared signature of standard, albeit unrealistic, homogeneous spherical ash particles, have been compared to realistic porous non-spherical ash particle shapes. The assumption of spherical ash particles is found to underestimate the volcanic ash cloud mass by about 30%. The impact of clouds on satellite detection and retrieval of volcanic ash has been investigated by a model sensitivity study. The sensitivity study was made for the two recent eruptions of Eyjafjallajökull (2010) and Grímsvötn (2011) using realistic ice and liquid-water clouds and volcanic ash clouds. Ice and liquid-water clouds were on average found to reduce the number of detected ash-affected pixels by 6-12% . The presence of clouds overall increased the retrieved mean ash-mass loading for the Eyjafjallajökull (2010) eruption by about 13 %, while for the Grímsvötn (2011) eruption the effect was a 4 % decrease. However, larger differences were seen between scenes (standard deviations of ±30 and ±20 % for Eyjafjallajökull and Grímsvötn, respectively) and even larger ones within scenes. A novel software package for reconstruction of three-dimensional volcanic plume structure from ground based infrared camera measurements, have been developed. The reconstruction method is based on the simultaneous iterative reconstruction technique and is available from http://folk.nilu.no/~arve/software/index.html.

The EC-funded FUTUREVOLC project will establish an innovative volcano monitoring system and strategy to achieve best practise in future volcano monitoring, early warnings, and eruption response at a European level. Within FUTUREVOLC, NILU is responsible f or the improvement of remote sensing of volcanic ash and sulphur dioxide by improving existing methods and development of new methodologies. Both retrieval algorithms for satellite infrared (IR) measurements and ground-based IR cameras will be improved a nd developed. NILU is collaborating with the Norwegian company Nicarnica Aviation, an SME, on the ground-based IR camera development. Also, NILU will act as a work package (WP) leader of WP 8 'Distribution and description of eruptive products'. As the W P 8 leader NILU coordinates WP 8 activities and participates in annual WP leader meetings. Collaborative work with the University of L'Aquila, CETEMPS, will be carried out to investigate the potential of merging satellite-borne microwave and thermal infra red ash measurements. Together with researchers from SMHI we will investigate the effect of non-sphericity of ash particles on infrared radiation. Finally, the results from FUTUREVOLC and the present proposal will be presented at relevant national forums.