Breakout Summary Report

Breakout Description

Although new particle formation accounts for a significant fraction of atmospheric particles, the chemical processes and species leading to the formation of stable nuclei (nucleation) and their subsequent growth remain poorly understood. These uncertainties are hindering efforts to model formation and growth of secondary aerosols on regional and global scales and to assess their atmospheric impacts. This session solicits contributions that describe research progress on atmospheric new particle formation, including laboratory studies, theoretical calculations and modeling at various scales, field measurements, studies that examine the spatial extent of aerosol nucleation and growth, and studies on the effects of cloud processing/conditions and meteorology on aerosol nucleation and growth. This topic has been a particular strength of ARM and ASR research over the years, and still is one of the most active areas of ASR-funded research, but we have not held a breakout at a PI meeting since 2016. The goals of this session are to share our mutual interests in new particle formation, identify areas of potential collaboration (especially between observationalists and modelers), and plan future activities such as field or lab campaigns.

Main Discussion

A brief introduction was followed by 12 talks by the research community on their new particle formation (NPF) research. This was particularly important since, as mentioned able, we have not met as a group for several years. The last 45 min of the session was devoted to discussion. The following questions were posed to facilitate discussion:

1. What aspects of new particle formation science are you most excited about?


2. Have you used ARM data for NPF research? If so, what have you done? If not, why not and how can ARM better instrument their sites for NPF research?


3. How can this community work together to progress NPF research? (e.g., field campaign? Chamber campaign?)


4. Do you have any questions for any of the speakers?

With regards to these four topics, the following was discussed:

Topic 3 (field campaigns)

Tony Wexler described EPA supersite in Baltimore 2000 – 2001; SPMS >50 nm; (maybe still) Steel mill, Chesapeake; Ship traffic; he also noted significant challenges in security of the site (it was vandalized). 

Jerome Fast suggested that we would want simultaneous measurements and multiple platforms (TBS, Arctic Sshark; Aircraft; surface). ARM often identifies availability of one platform or another – needs coordination.

Coty Jen discussed the large uncertainty in (especially) gas-phase measurements and variability among multiple instruments, e.g., CIMS. If multiple instruments are used in the same campaign, we should propose a pre-campaign instrument intercomparison.

Topic 2 (ARM measurements):

There was a lot of discussion about the TBS system given the importance of capturing NPF events aloft. 

For additional instrumentation, condensation particle counter"banks" (counters operating in parallel with difference lower cut-off diameters) could give growth rates. 

Jim Smith noted that, on paper anyway, one could collect on impactor stages to separate Aitken from accumulation modes. 

Gannet Hallar strongly encouraged turbulence measurements.

Jian Wang noted that we should expand TBS to other sites (e.g., ENA).

Andy Glen responded to say that we want to expand to other sites (permissions, etc.) – NSA and ENA.  They have been working on turbulence sensors.

Topic 4 (specific comments on the presentations):

Dubey commented on Jeff Pierce’s talk regarding the need to understand source regions better. We need to find sites where there is a large range of concentrations of precursors and NPF.

Finally, Gannet Haller (co-chair of Aerosol Measurment Science Group, AMSG) said that AMSG has thought about when instruments should be operated continuously, when intermittently, and when PI-provided.  There will be a workshop in 2024 – soliciting input.

Key Findings

THe following important findings came from this session:

• Importance of gas-phase precursors of new particle formation and being able to measure them. This may include sulfuric acid, amines, etc.


• We also need better measurements of SO2 (note that most of the time we are below the detection limit of the ARM SO2 monitor ... we need more sensitive measurements) and NOx and NH3. 


• Need measurement of VOCs (IVOCs, …) that go beyond just PTR-MS.


• Models are at the point where they can evaluate different mechanisms given good measurements of precursors. 

Issues

No issues were identified.

Needs

See "Key Findings" section for a discussion regarding the importance of measurements of gas-phase precursors of new particle formation and growth. This appears to be the most pressing need at the moment. 

Decisions

No decisions were made.

Future Plans

We plan to continue our discussions and look forward to opportunities to work together. No specific plans were discussed. 

Action Items

No action items were presented.