Breakout Summary Report

ARM/ASR User and PI Meeting

19 - 23 March 2018

Session Title: Absorbing aerosols and interactions with clouds
Session Date: 22 March 2018
Session Time: 10:45 AM - 12:45 PM
Number of Attendees: 30
Summary Authors: Paquita Zuidema and Allison Aiken

Breakout Description

A sequence of talks as described in the following agenda:
Towards defining the LASIC aerosol single-scattering-albedo: 10:45-11:30 est
Art Sedlacek - Refractory black carbon
Tim Onasch - LASIC CAPS measurements
discussion: What do we still need to do to come up with a ‘best-estimate’ SSA?

3. Yan Feng - Meteorological influences on biomass burning aerosol long-range transport: Observations versus CAM5 simulations


Other observational perspectives: 11:35-12:05 est
6. Yann Blanchard - Cloud properties from zenith-pointing and scanning cloud radars: statistics and implications
7. Ewan O’Connor - Inferences on turbulence from the Doppler lidar
8. Rob Wood: Ultra-clean conditions at Ascension
9. Laura Riihimaki - Update on VAP status
discussion:

Perspectives from modeling studies: 12:10-12:45 est
10. Tak Yamaguchi - Perspectives on absorbing-aerosol-cloud interactions gained from recent modeling studies
11. Xiaohong Liu - WRF-Chem simulations of the southeast Atlantic

Main Discussion

A good discussion on the absorbing aerosol measurements, with an emerging consensus that most of the absorption is coming from coated black carbon, and little brown carbon. CAPS absorption measurements support those from the PSAP.
Yann Blanchard's presentation highlighted the properties of cumulus clouds at ASI, primarily from 2017 when cross-wind RHIs are available. Rob Wood's presentation highlighted the presence of ultra-clean conditions at ASI, that they are most prevalent in the boreal fall when the LWPs are highest, and that they do not necessarily coincide with low-CO events. Laura Riihimaki provided an update on the VAPs available for Ascension. Tak Yamaguchi gave a good historical timeline on process modeling studies of smoke interacting with clouds, followed by discussion by Xiaohong Liu on a WRF-Chem study of aerosols mixing into the cloudy boundary layer.

Key Findings

See Main Discussion.

Issues

The surface-based observations still need to be more fully integrated with the vertical structure findings provided by the aircraft-based UK CLARIFY and NASA ORACLES projects.

Needs

The available aerosol size distributions need to be integrated with each other to provide a comprehensive best aerosol size distribution. The impact of orography on the cloud properties characterized at AMF1 needs to be quantified. A best-estimate aerosol vertical structure from the MPL still needs to be finalized.

Decisions

A cloud droplet number concentration VAP will be developed.

Future Plans

See Needs and Issues.

Action Items

See Needs Issues and Decisions.