Cloud physics phenomena updrafts warm rain downdrafts detrainment

Cloud physics phenomena (updrafts, warm rain, downdrafts, detrainment) and flight plans Zhiqiang Cui

WP 3. Aerosol, Cloud and Precipitation Processes (Objectives 2 - 4) 2. Determine if the warm rain process can be accurately quantified using the properties of the aerosols (CCN and GCCN) and understanding of the effects of turbulence and entrainment and mixing in large-eddy and largerscale models. 3. Understand the process of formation and development of downdraughts, cold pools and gust fronts, and the production of new convection at the head of the gust front. 4. Determine the geometrical shapes and cloud particle size distributions in the anvil-like detrainment layers at cloud tops, calculate the visible reflectance and compare with satellite measurements.

Frequency of occurrence Winter months in the Barbados region Gravel: 37% Sugar: 28% Fish: 27% Flower: 11% Rasp, Schulzy, Bony, Stevens, 2019

Stevens et al. 2019, QJRMS Sugar: 28% • No significant warm rain • Weak interactions & organization Gravel: 37% • Microphysical & BL processes • Interaction & organization Fish: 27% • Organization • Synoptic/mesoscale wind shears Flower: 11% • Expected to occur a couple times during our field campaign • Like large Sc system • Clear outflow layer

Three-hour period on 27 January 2012 at the BCO Precipitating cloud (Reflectivity > -20 d. Bz &Vd< -0. 5 m/s) Lamer et al. ( 2015) JGR.

2 -year data at the BCO Nonprecipitating cumulus Precipitating cumulus Cumulus segment of the precipitating cumulus with stratiform outflow ∆d. Bz = 15 Condenstional growth ∆d. Bz = -10 Entrainmnet /mixing Higher Reflectivity & enhanced downward Warm rain Heavier Precipitation Normalized cloud reflectivity colour map and Doppler velocity contours composites.

Precipitating Cu with attached stratiform outflow Thin detrainment outflow layer

Gravel BL measurements: cold pool, gust front, new convection, microphysics near cloud base Meso-scale control: w, fluxes Cloud microphysical processes (new, developing, old clouds along the arc)

• Flower: Cool, dry BL with strong inversion, like Sc • Model output: Use the above parameters to “forecast” the cloud types

Flower • Make circular run to measure the meteorological variables and aerosol close to the surface as low as safety requirements allow • Ascend and make few more circular runs to measure the MBL structure and the aerosol in the MBL

Detrainment and the outflow layer • Circular run to measure the cloud microphysical properties in the outflow region • Ascend • Continue to measure the structure of the outflow region • Ascend to the cloud top to measure the microphysical properties and possible entrainment at the cloud top If it is not easy to keep up with the flower, alternatively, we may make the straight runs in the upshear-downshear directions.

Many unanswered questions

Fish: 30 Jan 2009 ns nt itio e nd pm co elo ite ev ur d vo ud Fa clo r fo

Fish: 1 Feb 2013 Fish Gravel • Sample only a section of a fish • Along the elongated cloud system • Across runs