Microwave radar remote sensing of Plinian volcanic ash clouds for aviation hazard and civil protection applications

The potential of ground-based microwave weather radar systems for volcanic ash cloud detection and quantitative retrieval is evaluated. A prototype algorithm for volcanic ash radar retrieval (VARR) is discussed. Starting from measured single-polarization reflectivity, the statistical inversion technique to retrieve ash concentration and fall rate is based on two cascade steps: i) classification of eruption regime and volcanic ash category; ii) estimation of ash concentration and fall rate. An application of the VARR technique is finally shown taldng into consideration the eruption of the Grímsvötn volcano in Iceland on Nov. 2004. Volume scan data from a Doppler C-band radar, located at 260 km from the volcano vent, are processed by means of the VARR algorithm. Examples of the achievable VARR products are presented and discussed.