Tropospheric Modeling Studies of TRACE-P Data:
Investigation of the HOx/NOx/O3 Photochemical
System and its Coupling to Sulfur/Aerosol Species
Georgia Institute of Technology
Doug Davis (PI), Gao Chen (Co-PI), Shaw Liu, and Mian Chin
To be carried out our model based investigations of tropospheric
chemistry as related to the following questions and issues:
- What role do photochemical processes play in the western
North Pacific as related to the column ozone budget? More specifically,
how does the magnitude of photochemical ozone formation compare
with the ozone flux from the stratosphere for this region?
To what extent does the latter comparison change as one transitions
from late winter through spring and what factors are responsible
for this? And finally, how does Pacific Rim outflow impact
on the photochemical ozone budget in the central and eastern
North Pacific?
- What are the relative contributions of primary and secondary
NOx sources to the active pool of photochemical
NOx, in the western North Pacific? And, to what
extent is this balance perturbed by Pacific Rim outflow?
- What are the controlling factors that dictate HOx levels
and therefore the oxidizing power in the western North Pacific?
And, to what degree is Pacific rim outflow influencing these
levels at remote locations in the Pacific?
- What are the relative contributions of biogenic versus anthropogenic
and/or volcanic sulfur sources in the North Pacific in the
production of H2SO4(g) and sulfate; and
do these contributions change significantly as a function of
distance from the northwestern Pacific rim?
- What are the chemical and physical factors controlling H2SO4 (g)
and sulfate levels in the western North Pacific and how is
this setting altered by Pacific Rim outflow.? What evidence
is there for new particle formation in the form of binary nucleation
versus other forms such as ternary or ion controlled nucleation?
Can new particle formation occur on the fringes of continental
plumes or are aerosol growth processes dominating?
- What is the degree to which mineral aerosols associated with
the spring outflow influence the chemical conversion and scavenging
of non-sulfur species, i.e., NOy and HOx species.
Investigation of these issues and questions will build on earlier
work completed during PEM-West A and B, PEM-Tropics A as well as
that from on-going analyses of PEM-Tropics B data. Data analysis
will involve the use of both DC-8 and P-3B TRACE-P airborne observations.
The analysis will engage several versions of a basic box model
including: a time-dependent photochemical box model with and without
coupling to a sulfur/aerosol chemistry module, a Lagrangian photochemical
model, and an aerosol-dynamic sectional model that can be used
to simulate the temporal variations in the aerosol size distributions.
Interpretation of the output from these models will be supplemented
with data from trajectories, satellite imagery, and ozonesonde
information. It is also expected that some data will be made available
from the ACE-Asia field program and that some degree of collaboration
with some members of the science team will take place. Given our
past collaboration with the modeling group within the Atmospheric
Sciences Division at NASA Langley, we again anticipate several
collaborative efforts with this group during TRACE-P.
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