April 8, 2022 - 3:00 pm
April 8, 2022 - 4:00 pm
CategoriesConvective Meteorology (Mesoscale Dynamics)
Convective Meteorology (Mesoscale Dynamics)
Turbulent Supersaturation Fluctuations and Cloud Droplet Spectral Broadening observed during HI-SCALE and CACTI
Friday, April 8
NWC 5600/ online
Cloud droplet spectral broadening is one of the unsolved problems in the warm rain processes, and several hypotheses have been proposed, including the influence of turbulence and aerosol. In-situ cloud observations and detailed cloud microphysical models are needed to examine these hypotheses. Two of the recently completed experiments from the U.S Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) collected valuable meteorological and cloud microphysical data with the DOE G-1 aircraft equipped with state-of-the-art meteorological, aerosol, and cloud instrumentations. One experiment is the Holistic Interactions of Shallow Clouds, Aerosols, and Land-Ecosystems (HI-SCALE) experiment conducted in ARM Southern Great Plain site, and the other is the Cloud, Aerosol, and Complex Terrain Interactions (CACTI) experiment, which was conducted in the Sierras de CÃ³rdoba mountain range of north-central Argentina. In this study, cloud microphysical measurements from the fast cloud droplet probes (FCDP) installed on the G-1 aircraft are post-processed to higher resolutions (20HZ) and analyzed in addition to the two-dimensional stereo (2D-S) probes 2 to study the influence of turbulence on supersaturation fluctuations and correspondingly the broadening of droplet size distribution. The turbulence intensity is represented by the standard deviation of vertical velocity that was measured by the Aircraft-Integrated Meteorological Measurement System (AIMMS-20). The quasi-steady state supersaturation was estimated using the number concentration and vertical velocity, because supersaturation measurements are often poorly known and rarely measured directly. . With the high resolution dataset, a high resolution supersaturation can be calculated and the fluctuations of supersaturation that has often been overlooked with low resolution dataset can be further examined. We found that the mean radius and spectral width of cloud particle size distributions increase as the turbulence intensity increases. Therefore, particle size distributions broaden with higher turbulence intensity. A Lagrangian cloud particle model is further utilized to simulate a warm rain initiation event, and the evolution of cloud particle size distribution and bulk microphysical properties in the 1D column setting. The simulation results will be compared with in-situ observations from HI-SCALE and CACTI.