Graupel Microphysical Properties and 95 GHz Attenuation from Airborne Doppler Cloud Radar and in-Situ Microphysical Observations

Recent studies have shown that jet engine power loss and damage could be attributed to a form of engine icing that was not previously well recognized. This condition, now referred to as "ice crystal icing”, is associated with the production of high concentrations of small ice crystals around deep convective cores. In order to study the conditions of formation and maintenance of these so-called High Ice Water Content (HIWC) regions and update the existing regulations with respect to ice crystal icing, the international regulatory authorities and scientific community organized two field experiments where airborne cloud radar and in-situ microphysical measurements were collected within and around deep convective cores. The observations from these experiments (Darwin, Australia, 2014 and Cayenne, French Guiana, 2015) are used in this work to derive quantitative information on the microphysical properties of graupel particles within tropical convective cores. Three-dimensional wind retrievals from the multi-beam RASTA cloud radar are also analysed to provide a dynamical context to the microphysical observations. Characterizing the microphysical properties of graupel, and understanding their interaction with the dynamics and latent heat release will help to develop new parameterization of graupel properties in cloud-resolving models. In this work we also take advantage of these unique observations to characterize the 95 GHz attenuation associated with graupel, as well as within aggregation-dominated regions of mesoscale convective systems. It is important to ensure that 95 GHz attenuation is accurately corrected for in areas surrounding the sampled tropical convective cores.