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More information on some input arrays can be found when moving the cursor above the corresponding field in the questionnaire. Those fields are also explained in the glossary.

IMPACT: Integrated Massively Parallel Atmospheric Chemistry Transport Model

General information

Model name and version

short nameIMPACT
full nameIntegrated Massively Parallel Atmospheric Chemistry Transport Model
revisionT5A
dateSept 2006
last change

Responsible for this information

nameCyndi Atherton
instituteLawrence Livemore National Laboratory
addressP.O. Box 808, L-170, Livermore, CA 94551, USA
zip94551
cityLivermore, CA
countryUSA
phone925-422-1825
fax925-423-1098
e-mailatherton2(belongs-to)llnl.gov

Additional information on the model

Contact person for model code

same as person above
nameDan Bergmann
instituteLLNL
divisionsEnergy & Environment Directorate
street7000 East Avenue
zip94551
cityLivermore, CA
countryUSA
phone925-423-6765
emailbergmann1@llnl.gov
fax925-423-4908

Model developer and model user

developer and userRotman, D.A., C.S. Atherton, D.J. Bergmann, P.J. Cameron-Smith, C.C.Chuang, P.S. Connell, J.E. Dignon, A. Franz, K.E. Grant, D.E. Kinnison, C.R. Molenkamp, D.D. Proctor, J.R. Tannahill, J. Kelly

Level of Knowledge needed to operate model

basic
intermediate
advanced
remarks

Model use at your institution

operational
for research
other use

Model code available?

is available?no
more details

Minimum computer resources required

type11 Tflops linux cluster
time needed for run18 month - 90 hrs/on 64 processors
storage200 - 300 Gbytes

Further information

documentationRotman, D.A., C.S. Atherton, D.J. Bergmann, P.J. Cameron-Smith, C.C.Chuang, P.S. Connell, J.E. Dignon, A. Franz, K.E. Grant, D.E. Kinnison, C.R. Molenkamp, D.D. Proctor, J.R. Tannahill, 2004: IMPACT, the LLNL 3D global atmospheric chemical transport model for the combined troposphere and stratosphere: Model description and analysis of ozone and other trace gases, J. Geophys. Res., 109 doi:10.1029/2002JD003155.
model referencesRotman, D.A., C.S. Atherton, D.J. Bergmann, P.J. Cameron-Smith, C.C.Chuang, P.S. Connell, J.E. Dignon, A. Franz, K.E. Grant, D.E. Kinnison, C.R. Molenkamp, D.D. Proctor, J.R. Tannahill, 2004: IMPACT, the LLNL 3D global atmospheric chemical transport model for the combined troposphere and stratosphere: Model description and analysis of ozone and other trace gases, J. Geophys. Res., 109 doi:10.1029/2002JD003155.
webpage
additional information

Model properties

Model type

2D
3D
meteorology
chemistry & transport

Model scale

microscale
mesoscale
macroscale
short term
long term

Meteorological variables

Input data
u
v
w
ζ
pv
T
θ
θl
p
Gph
ρ
qv
qt
qlc
qf
qsc
qlr
qsh
qsg
qss
N
E
ε
K
zi
other variables i
other variables ii
other variables iii

Chemical substances

PrognosticDiagnosticDry depositionWet depositionInput data
SO2
NO
NO2
NOX
NH3
HNO3
O3
CH4
DMS
H2O2
VOC
C6H6
HCHO
CO
CO2
POP
PM 10
PM 2.5
PPM10
PM 0.1
PM 1
NH4
SO4
dust
sea salt
BC
POM
SOA
NO3
Other gases
1st radioactivity
2nd radioactivity
3rd radioactivity
Cd
Pb
other heavymetals
pesticides
1st radioactivityRn/Pb
2nd radioactivityBe7, Be10
3rd radioactivity
remarks

Approximations

Boussinesq
anelastic
hydrostatic
flat earth
remarks

Parametrizations

Chemistry & transport

photolysis rateFast JX (Wild & Prather)
dry depositionWang (1998) and Wesely (1985)
wet depositionMari et al., 2000; Liu et al., 2001; Girgi and Chameides, 1986; Balkanski et al., 1993
remarks

Chemical reactions

Gas & wet phase chemistry

chemical transformations calculated
chemical transformations neglected
other
gas phase chemistry (give details)See Rotman et al. 2004 Tropospheric chemistry includes CO,CH4, C2H6, C3H8, C2H4, C3H6, C4H10, isoprene, NO, NO2, O3, OH, HNO3, NO3, PAN, PPN, etc. Solution technique: SMVGEAR II (Jacobson 1995) Total thermal reactions: 134 Total photolytic reactions: 32 Total calculated species (gas): 68 Total calculated aerosol: 11
wet phase chemistry (give details)H2O2 + SO2 O3 + SO2 solution phase processes; treated as equilibrium each timestep
more informationChemical processes are calculated based on climatological surface area densities. Photolysis calculations take into account the actual prognostic aerosol quantities. For this calculation, we are only calculating ozone in the troposphere, and using an algorithm for supplying the correct flux from the stratosphere (synoz), and we specify climatological stratospheric ozone for the photolysis calculations.

Aerosol chemistry

passive aerosol
dry aerosol
wet aerosol
sectional approach
modal approach
other
nucleation
coagulation
condensation
aerosol mixing
aerosol ageing
primary aerosol formation
aerosol-gas phase interactions
optical properties
give details

Initialization & boundary treatment

Initialization

chemistry & transportWe initialized with previous model results from a 'settled' present-day full chemistry model calculation. (Rotman et al., 2004)
meteorology

Input data (name sources for data, e.g. website)

orographyDAO product
land use
obstacles
vegetation
meteorologyNASA/DAO - use GEOS3 fields for this particular simulation.
concentrationsFrom a previous present-day IMPACT global simulation
emissionsCombination of sources from POET, GFEDv2, AEROCOM, IPCC 2007, IGAC
remarksThis is a long form.

Data assimilation

Chemistry & transport
nudging technique
adjoint model
3D-VAR
4D-VAR
OI
detailsWe are supplied NASA/GEOS 3 metfields, which have already been assimilated.

Boundary conditions

Chemistry & transport
surfacePrescribed CH4 and H2 throughout atmosphere for these calculations
topBecause the model extends to the top of the stratosphere, we do not have a 'top' b.c.
lateral inflowN/A - global model
lateral outflowN/A - global model

Nesting

Chemistry & transport
one way
two way
other
variables nested
nesting online
nesting offline
data exchange by array
data exchange by file
time step for data exchange
explain method
variables nested
other

Solution technique

Coordinate system and projection

Horizontal

cartesian
Lambert conformal
latitude / longitude
rotated lat. / long.

Vertical

z coordinate
surface fitted grid
pressurecoordinate
sigma coordinate
remarks

Numeric

Chemistry & transport

Grid

Arakawa A
Arakawa B
Arakawa C
Arakawa D
Arakawa E
uniform grid
nonuniform grid
Euler
Lagrange
Gauss

Time integration

explicit
split-explicit
semi-implicit
time step same as meteorology
other

Spatial discretisation

scalar quantities
additional information
other
chemistry solverSMVGEAR II (Jacobson 1995)

Model resolution

Chemistry & transport

HorizontalVertical
max250 km~3000 - 5000m
min250 km20m

Domain size

Chemistry & transport

HorizontalVertical
max80,000 m
minglobal0 m

Model Validation and Application

Validation & evaluation

Used validation & evaluation methods

analytic solutions
evaluated reference dataset
model intercomparison
additional validation & evaluation efforts
remarks

Application examples

application examplesPresent day Rotman et al., 2004 Present day and 2030 - IPCC 2007 - see Dentener, Stevenson, Shindell, etc. for specific papers Also see Chuang et al.

Participation in specific model evaluation exercises

AQMEII
List experiments (AQMEII)
Cost728
List experiments (COST728)
HTAP
List experiments (HTAP)
MEGAPOLI
List experiments (MEGAPOLI)