Microphysics of Cumulus Clouds over the Philippine and South China Seas

Abstract:

The CAMP²Ex field campaign offers a unique opportunity to investigate in situ microphysics of tropical cumulus clouds over the Philippine and South China Seas. The NASA P-3B and SPEC Incorporated Model 35A Learjet were both equipped with a suite of advanced microphysical instrumentation. The two aircraft worked a system of cumulus congestus (CuCg) clouds over the southern tip of Catanduanes Island on 25 September 2019, and the Learjet investigated a CuCg cloud system north of Luzon over open ocean on 13 September 2019. The CuCg cloud system over Catanduanes Island evolved into a mesoscale convective system during the investigation. The tops of CuCg clouds north of Luzon did not achieve temperatures colder than -10 °C. The data reveal that a coalescence process producing millimeter-diameter drops developed in both CuCg cloud systems by the 0 °C level. The Learjet sampled growing cloud tops and the data indicate that ice had developed in the 13 September cloud system at a temperature warmer than -10 °C. The structure of the convection is a series of thermal “bubbles” with downdrafts at the edges of the bubbles. There is also evidence of a secondary ice production process resulting from drop fracturing. Particle imagery from optical probes with four size resolutions support the measurements. Results from 3D numerical simulations that incorporate actual data are used to evaluate microphysical processes within the convection.