Breakout Summary Report

ARM/ASR User and PI Meeting

Session Title: High-latitude marine post-frontal clouds
Session Date: 24 June 2021
Session Time: 11:00 AM - 1:00 PM
Number of Attendees: 90
Summary Authors: Bart Geerts

Breakout Description

This session focused on how data recently collected over boreal and austral oceans from previous field campaigns can be used to address uncertainty in the simulation of extratropical cloud feedbacks. The intent of this session was to encourage collaborative observational and modeling work to advance the objectives of these campaigns.

Main Discussion

The first subject area was discussed in the first hour. There were active discussions on the most important extratropical cloud processes, related to the following topics: (1) concurrent measurements of size-resolved aerosol composition in addition to INP concentrations (such as AEROICESTUDY in SGP); (2) importance of ground-based radar/lidar for mixed-phase cloud ice in addition to satellite observations (e.g., CALIPSO) biased with large uncertainties; and (3) cloud dynamics (e.g., turbulence) important for microphysics, bringing the gap across models with different scales.

In the second hour, the microscale and macroscale structure of high-latitude marine post-frontal clouds was discussed, as follows: (1) a summary of the data status and preliminary results from the MARCUS and MICRE experiments in the Southern Ocean, and the COMBLE experiment in the Arctic; (2) observations of aerosol, cloud, and precipitation processes in these clouds, focused mainly on two questions: what is the dominant cloud phase & precipitation growth mechanism, and how do cloud processes affect the dynamics and mesoscale organization of these clouds; (3) the numerical simulation of these clouds, mainly using quasi-Lagrangian LES.

A full breakout session report can be viewed here.

Key Findings

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Issues

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Needs

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Decisions

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Future Plans

The main outcome of this discussion is that we are planning a “working discussion” on the topic of observations and modeling of high-latitude marine clouds in both hemispheres, esp. as related to the recent Southern Ocean experiments, COMBLE, and other campaigns (e.g., ACTIVATE) and sites (e.g., NSA, ENA). An announcement for this workshop (tentatively to be held in early September) will be circulated via the High-Latitudes Working Group email list.

Action Items

To the organizers: We really appreciate the scheduling of this breakout before the relevant poster session: many of the presentations referred to posters in the poster session immediately after this breakout.