Breakout Summary Report

 

ARM/ASR User and PI Meeting

10 - 13 June 2019

Marine Cloud-Topped Boundary-Layer (MBL) Processes: Cloud, Aerosol, Drizzle, and Turbulence
12 June 2019
10:30 AM - 12:30 PM
50
Xue Zheng and Robert Wood

Breakout Description

The session focused on cloud-aerosol-drizzle-turbulence interactions in the marine cloud-topped boundary layer. These interactions are important for determining cloud responses to greenhouse gases and aerosols, and their representation in large-scale numerical models continues to be a major challenge. The goal of the session is to provide participants of ARM/ASR-funded MBL projects with an opportunity to show and discuss their latest observational analyses, model simulations or assessments, and data products. Topics of relevance include:




  1. Case studies from recent

  2. Observational data analyses spanning multiple field campaigns or ARM sites

  3. Advanced observing techniques and retrievals

  4. MBL cloud, aerosols, and their interactions in numerical models

  5. Any other interesting MBL processes

Main Discussion

Agenda:



Observational Analyses [10:30-11:30]



  • A Three-Year Study of the Summertime Thermodynamic, Cloud, Sub-Cloud Turbulent Kinetic Energy, and Sub-Cloud Mixing Length from ENA Site. Presenter: Mark Miller [Rutgers University]

  • The Vertical Structure of Liquid Water Content in Shallow Clouds as Observed by Dual-Wavelength Radar. Presenter: Zeen Zhu [SUNY]

  • Observational Evidence of the Effect of Large-Scale Drivers on Marine Boundary-Layer Precipitation during Subsidence in the Eastern North Atlantic. Presenter: Katia Lamer [CUNY]

  • Episodes of Warm-Air Advection Causing Cloud-Surface Decoupling during MARCUS. Presenter: Youtong Zheng [University of Maryland]



Model Represenation and Evaluation [11:30-12:15]



  • Sensitivity of Marine Clouds Formed through Shallow Convection to Changes in Atmospheric Circulation and Model Physics. Presenter: James Booth [CUNY]

  • Assessment of Precipitating Marine Stratocumulus in E3SMv1: A Case Study during the ARM MAGIC Campaign. Presenter: Xue Zheng [LLNL]

  • Highly Supercooled Drizzling Stratus over Antarctica: A Good Test for Climate Models? Presenter: Israel Silber [Pennsylvania State University]



General Discussion [12:15-12:30]

Participants shared and discussed the latest observational analyses, model simulations, and data products related to MBL processes. We had seven presentations in total, which covered studies based on data from the ARM ENA site, the MAGIC field campaign, and the MARCUS field campaign. For the ENA region, we discussed




  • Long-term thermodynamic state and the sub-cloud TKE of the summertime MBL.

  • Vertical structure of liquid water in MBL clouds

  • Large-scale factors on MBL precipitation

  • Sensitivity of the shallow convective clouds to changes in model physics for post-cold-front case modeling.



For the MBL-related ARM field campaigns, we discussed an observational case of cloud-surface decoupling caused by warm-air advection during MARCUS and a model-observation inter-comparison case study on precipitating stratocumulus clouds during MAGIC. People also shared a follow-up study on the numerical issue in the bin microphysics scheme presented at previous the MBL session at the 2018 ARM/ASR PI meeting.

Key Findings

Science findings are summarized in the associated presentations uploaded to the meeting website.

Needs


  • Extend the long-term analyses of ENA data

  • Better understand the uncertainties related to different combinations of model physics in shallow convective clouds modeling

  • Release the PI retrieval products presented at this session to the ARM Data Center

Future Plans


  • Better understand post-cold-frontal clouds and precipitation over the ENA region

  • Study the sustaining mechanism of stratiform clouds in the highly decoupled MBL caused by warm-air advection over the Southern Ocean

  • Improve the model performance of MBL precipitating clouds at ENA

  • Keep applying ARM data to process-level model evaluation