Microphysical characterization of microwave Radar reflectivity due to volcanic ash clouds

Observation of non‐spherical ultragiant aerosol using a microwave radar

“…[3] Recently, microwave weather radars have been also used for monitoring the microphysical and dynamical features of volcanic plumes during the eruption phase using a physical-statistical approach [Marzano et al, 2006a[Marzano et al, , 2006b[Marzano et al, , 2010. These studies are referred to the observation of a high density of large size tephra particles emitted into the atmosphere that can be accurately studied also using the radar reflectivity.…”

“…These studies are referred to the observation of a high density of large size tephra particles emitted into the atmosphere that can be accurately studied also using the radar reflectivity. The performance of retrieval techniques for the estimation of particles size using the radar reflectivity in the S-, C-, X-, and Ka-band have been simulated and also successfully tested on experimental data [Marzano et al, 2006a[Marzano et al, , 2006b]. However, as far as we know, radar has been never used as a technique for monitoring the dispersion of the volcanic ash in the atmosphere over long spatial ranges.…”

Volcanological Applications of Doppler Radars: A Review and Examples from a Transportable Pulse Radar in L-Band

“…(ii) By using singlepolarization weather radar, however, it is fairly difficult to discriminate between ash, hydrometeors, and mixed particles. Ice nucleation and subsequent loss in reflectivity also make ash detection more difficult (Marzano et al, 2006b). These authors suggest that polarimetric radars may improve discrimination of the impact of cloud ice and liquid water on ash aggregates.…”

“…According to Marzano and Ferrauto (2003), in the case of hydrometeors, any radar technique above S band should take into account, and possibly remove, path attenuation effects in order to correctly convert measured reflectivity into rain rate. For ash clouds, Marzano et al (2006b) concluded that Cband may offer some advantages in terms of radar reflectivity response and negligibility of path attenuation. While still tolerable at X-band, the path attenuation cannot be handled at Ka-band.…”

Monitoring Volcanic Ash from Space

“…Some advanced plume models can simulate the interactions of hydrometeors and volcanic ash, including aggregate particle formation within a rising eruption column (Marzano et al, 2008(Marzano et al, , 2010b. In order to quantitatively evaluate the ash retrieval by weather radars, a prototype algorithm for volcanic ash radar retrieval (VARR) has been recently formulated and discussed (Marzano et al, 2006b(Marzano et al, , 2010b. Starting from measured single-polarization reflectivity, the estimation method is based on two cascade steps: i) a classification of eruption regime and volcanic ash category; ii) estimation of ash concentration and fall rate.…”