1
TSD
1.
Linking
Global
Model
(
GOES­
CHEM)
with
Regional
Model
(
CMAQ)

In
this
section
we
describe
the
approach
used
to
provide
the
boundary
conditions
(
BCs)
for
the
CAIR
CMAQ
modeling.

Nonepisodic
regional
air
quality
modeling
such
as
CAIR's
annual
continental
U.
S.
modeling
requires
the
prescription
of
BCs
to
account
for
the
influx
of
pollutants
and
precursors
from
the
upwind
boundaries.
Most
of
current
regional
modeling
practices
use
static
temporal
and
spatial
BCs,
or
fixed
BCs,
to
prescribe
the
species
concentrations
for
the
four
lateral
and
top
boundaries.
The
fixed
BCs
approach
would
be
problematic
if
the
pollutant
influxes
from
the
upwind
boundaries
which
are
often
dynamic
in
nature
could
affect
pollutant
concentrations
within
the
modeling
domain.
For
example,
a
number
of
recent
studies
showed
that
long­
range
transport
of
pollutants
could
contribute
to
the
levels
of
ozone
and
PM
in
the
United
States
with
seasonal
variations
(
Jacob,
et
al.,
1999;
Jaffe
et
al.,
2003;
Fiore,
et
al.,
2003).
A
scientific
sound
approach
is
to
use
a
global
chemistry
model
to
provide
dynamic
BCs
for
the
regional
model
simulations.

Under
the
CAIR
modeling
effort,
we
use
a
global
threedimensional
chemistry
model,
the
GOES­
CHEM
model,
to
provide
the
BCs
for
CMAQ
continental
U.
S.
modeling.
The
global
GOES­
CHEM
model
simulates
atmospheric
chemical
and
physical
processes
2
driven
by
assimilated
meteorological
observations
from
the
NASA's
Goddard
Earth
Observing
System
(
GEOS)
(
please
refer
to
http://
www­
as.
harvard.
edu/
chemistry/
trop/
geos/
index.
html
for
further
details
of
GOES­
CHEM).
We
use
an
interface
utility
tool
developed
at
University
of
Houston
(
Byun
and
Moon,
2004;
Moon
and
Byun,
2004)
to
link
the
GOES­
CHEM
with
CMAQ.
The
global
GOESCHEM
model
was
conducted
at
2
degree
x
2.5
degree
(

latitudelongitude
grid
resolution
with
20
vertical
layers
and
the
results
were
used
to
provide
one­
way
dynamic
BCs
in
every
3
hours
to
the
annual
CMAQ
simulation
at
36­
km.
The
scale,
chemical,
and
dynamic
linking
between
the
two
models
are
needed
since
the
horizontal
and
vertical
coordinates,
chemical
species
representations,
and
model
output
time
are
different.
A
detailed
description
of
data
preparation,
spatial
and
temporal
conversion
procedures,
and
species
mapping
tables
are
given
in
Moon
and
Byun
(
2004)
and
available
at
"
http://
www.
math.
uh.
edu/~
dwbyun/
Meetings/
icap/".

REFERENCES:

Jacob,
D.
J.,
J.
A.
Logan,
and
P.
P.
Murti,
"
Effect
of
Rising
Asian
Emissions
on
Surface
Ozone
in
the
United
States",
Geophy.

Res.
Lett.,
26,
2175­
2178,
1999.

Jaffe
D.,
McKendry
I.,
Anderson
T.,
and
Price
H.
"
Six
'
new'

episodes
of
trans­
Pacific
transport
of
air
pollutants",
Atmos.

Envir.
37,
391­
404,
2003.
3
Fiore,
A.
M.,
D.
J.
Jacob,
H.
Liu,
R.
M.
Yantosca,
T.
D.

Fairlie,
and
Q.
Li,
"
Variability
in
surface
ozone
background
over
the
United
States:
Implications
for
air
quality
policy",
J.

Geophys.
Res.,
108,
4787,
2003.

Moon
N.
K.,
and
D.
W.
Byun,
"
A
Simple
User's
Guide
for
"
geos2cmaq"
Code:
Linking
CMAQ
with
GEOS­
CHEM,
Version
1.0",

Interim
Report
from
Institute
for
Multidimensional
Air
Quality
Studeis
(
IMAQS),
University
of
Houston,
TX,
August
2004,

http://
www.
math.
uh.
edu/~
dwbyun/
Meetings/
icap/.

Byun
D.
W.,
N.
K.
Moon,
Daniel
Jacob,
and
Rokjin
Park,

"
Regional
Transport
Study
of
Air
Pollutants
with
Linked
Global
Tropospheric
Chemistry
and
Regional
Air
Quality
Models",
2nd
ICAP
workshop,
RTP,
NC,
October
2004,

http://
www.
cep.
unc.
edu/
empd/
projects/
ICAP/
2004wkshp_
pres.
html.
