Group 1. Nucleation working group (McMurry & Clarke)
The discussion focused on nucleation-related papers that are being
considered. The following topics were mentioned:
For the June 1, JGR submission:
- Rodney Weber, Peter McMurry, Eisele and coworkers, Bradshaw
and coworkers; Kreidenweis and coworkers: Rodney Weber is working
on a paper that describes the nucleation event observed downwind
of Macquarie Island. The paper will examine the relationship
between particle production and precursor gases such as H2SO4
and NH3, and will investigate particle production rates as well
as particle growth rates. Measurements on Macquarie Island will
be incorporated in this paper to provide information about initial
Work planned for the future:
- Sonia Kreidenweis and coworkers: 2-D cloud dynamics model
with coupled chemical model to investigate processes that lead
to nucleation at outflow regions from convective clouds.
- Lynn Russell and John Seinfeld: 1-D hybrid cloud dynamics
model with coupled chemical model to investigate processes that
lead to nucleation at outflow regions from convective clouds.
- Doug Davis and Gao: Model for nucleation induced by mixing
and chemical transformations in cloud outflow regions. High time
resolution data from the C-130 fro species including 03, H2O,
H2SO4, and Nox should be useful in evaluating model predictions.
- Tony Clarke: Is working on a "nucleation climatology"
survey paper that will summarize conditions (aerosol surface areas,
local events such as cloud outflow, etc.) That lead to nucleation.
- Allen Bandy and coworkers: Have developed an alternative
model for nucleation based on chemical arguments that reactions
between H2SO4 and clusters are kinetically limited. They plan
to compare predictions of their model with data acquired in ACE-1.
- Jingxia Zhao, Tony Clarke, and Jamie Li: Jingxia Zhao has
developed a theory for nucleation in the atmosphere. She plans
to work in collaboration with Clarke and coworkers to compare
model predictions with ACE-1 data.
- Rodney Weber, Peter McMurry, Eisele and coworkers, etc:
This group is planning to study data for nucleation in cloud outflow
regions in an effort to determine the relationship between particle
production and growth rates and concentrations of gas phase precursors.
- Rodney Weber plus other groups with CNC data: Rodney has
compared data from CNCs on the C-130. This comparison provided
useful insights, for example, into conditions that lead to droplet
shatter. Because droplet shatter produced particles in the nanoparticle
range, there is a potential for confusing droplet shatter events
with nucleation events. Although this paper is not aimed at nucleation,
this work must be completed before the C-130 data can be used
to obtain information about nucleation. Rodney has also compared
C-130 data with data from Macquarie, the Discoverer, and Cape
Grim for periods when the aircraft was in the vicinity. He does
not plan to compare CNC data of the Discoverer and ground sites
when the ship was upwind of those sites.
- Rodney Weber, Mark Stolzenburg, Spyros Pandis, and Peter
McMurry: A paper on the inversion of pulse height data to obtain
size distributions in the 3-10 nm diameter range will be submitted
to the Journal of Aerosol Science by mid April for review for
inclusion in a special issue on nanoperticles. Some of the Macquarie
Island data will be included in this paper to illustrate distributions
that are obtained when nucleation is occurring. This paper will
not include an in depth discussion of the Macquarie Island data.