Friday, 7 June 2002
In situ measurements of particle size distributions in Hurricane Humberto
Microphysical measurements were acquired aboard the NASA DC-8 aircraft during the Fourth Convection and Moisture Experiment (CAMEX-4) field campaign in August and September of 2001. A suite of particle imaging instruments, including upgraded versions of the PMS 2D-C, 2D-P, and FSSP, as well as a SPEC, Inc. Cloud Particle Imager (CPI), recorded ice particle images, sizes, and concentrations across a large size range. We present measurements that were made by these instruments during an intensive 3-day study of Hurricane Humberto on September 22, 23, and 24. Observations include surprisingly high particle concentrations and large particles (3mm) at altitudes up to 39000 feet. Variations in particle size spectra and derived bulk parameters are shown as functions of storm-relative location and storm maturity. The observed spectra are fit with gamma functions for comparison with previously reported tropical particle size distributions.