Breakout Summary Report


ARM/ASR User and PI Meeting

Warm Boundary-Layer Processes Working Group Breakout
27 October 2022
2:00 PM - 5:00 PM
Rob Wood and Yunyan Zhang

Breakout Description

The Warm Boundary-Layer Processes Working Group focuses on understanding and model representation of processes controlling the structural and radiative properties of clouds, aerosols, and their interactions with the underlying surface in the lowest few kilometers of the atmosphere. Research areas 10 2022 ARM/ASR Joint User Facility PI Meeting Breakout Session Announcements include: 1) characterization of boundary-layer and cloud dynamics; 2) cloud and aerosol microphysics and their interactions; 3) factors influencing cloud formation; and 4) radiative processes that together influence the vertical transfers of energy, moisture, and atmospheric components.

Main Discussion

Warm Boundary-Layer Processes (WBLP) Work Group breakout hosted talks and discussions related to boundary-layer turbulence, thermodynamics structures, cloud and drizzling microphysical processes and their interaction with aerosols, and the underlaying surface properties.

The session started with:

  • several highlights of workshops and a new SFA highly relevant to WBLP

  • requests of community inputs on ARM data gap and CPMSG surveys

  • an infrastructure update on ARM data development relevant to WBLP processes.

Then the session ran into three divided periods that roughly grouped different topical areas of WBLP:

  • PBL and interaction with land surface

  • cloud dynamics and microphysics

  • aerosol-cloud interactions.

As this was the first hybrid gathering in the last three years and the last session of this annual meeting, each of the three periods hosted one or two long talks (10 to 12 minutes) and four to five short talks (5 minutes or up to 3 slides).  Although the session was first overwhelmed by many contributed short talks, the 5-min talks combined with a few long talks worked very well to promote Q/A and short discussions, and a great opportunity for WG members to get on to the key points directly and showed a broad spectrum of our most recent work to each other. We received several positive feedbacks on this.   

Key Findings

The ARM infrastructure recent data developments highly relevant to WBLP WG include: 1) PBLH from multiple instruments, 2) COGS from stereo camaras, 3) Cloud optical depth, droplet effective radius and LWP from Cimel sunphotometer, 4) aerosol VAPs, 5) LASSO-O bundles, and 6) large-scale forcing data.

As we have uploaded all the talks into three or four combined PDF files available online, here we are attaching the session agenda for references (long talks are highlighted). For details, please refer to the slides.

  1. “Coastal urban boundary-layer characteristics” (Prathap Ramamurthy)

  2. “Stochastic generation of heterogeneous patterns representing natural landscapes” (Zun Yin)

  3. “Spatial variability of convective mixing layer at the SGP supersite” (Zhien Wang)

  4. “Effects of NWP-based large-scale forcing on real-case LES: Statistical analysis of multi-year LASSO LES of shallow convective clouds” (Hyeyum Hailey Shin)

  5. “Quantifying the contributions from the surface, advection, and entrainment on the evening transition at SGP” (Siwei He and Dave Turner) 

  6. “Evolution of droplet size distributions during the transition of an ultraclean stratocumulus cloud system to open cell structure” (Kamal K. Chadrakar)

  7. “Effect of wind shear on precipitating marine stratocumulus clouds under different aerosol conditions” (Mikael Witte and Jong-Hoon Jeong)

  8. “Aerosol-boundary layer interaction-modulated entrainment process” (Tianning Su and Zhanqing Li)

  9. Using ARM’s spectroradiometer observations for studying cloud mixing processes and near-cloud aerosols (Alexander Marshak, Guoyong Wen, and Weidong Yang)

  10. “Stratocumulus-surface decoupling prolongs cloud lifetime: the mechanism” (Haipeng Zhang, Youtong Zheng and Zhanqing Li)

  11. “Stratocumulus susceptibility across time and cloud scales” (Xiaoli Zhou)

  12. “Numerical and physical sensitivities in large-eddy simulations of plume lofting and spread” (Chandru Dhandapani)

  13. “The impact joint variability of liquid water and droplet concentration on grid-mean autoconversion and enhancement factor” (DB Mechem and JA Covert)

  14. “Supersaturation in the marine boundary-layer clouds over the Eastern North Atlantic” (Jian Wang)

  15. “ENA warm boundary-layer clouds and their responses to aerosol perturbations from ARM observations and geostationary satellite cloud retrievals” (Xue Zheng)

  16. “Understanding the microphysical control and spatial-temporal variability of warm rain probability using CloudSat and MODIS observations” (Zhibo Zhang)

  17. “Addressing structural errors in warm-rain microphysics with BOSS, a Bayesian data-driven, physically based, bulk scheme” (Marcus van Lier-Walqui)


There was a line connection problem with the projector that kept putting the “zoom” window from full screens back to small windows at the first few minutes and it was really disturbing.  But it got stable and went well for the rest of the session.





Future Plans


Action Items