CO2 CONDENSATION IN THE MARTIAN ENVIRONMENT Xin Guo, Claire E' Newman, Mark I' Richardson, Stephen E

1
CO2 CONDENSATION IN THE MARTIAN ENVIRONMENT Xin
Guo, Claire E. Newman, Mark I. Richardson,
Stephen E. WoodPlanetary Science, Division of
Geological and Planetary Sciences, California
Institute of Technology, Pasadena, CA
P23A-0041

• ABSTRACT
• It has been suggested that cirrus cloud formed of
  CO2 gas may have significantly affected the early
  history of the climate of Mars. Evidence of the
  existence of CO2 ice clouds in the current
  atmosphere of Mars has also been reported. We
  implement a CO2 microphysics scheme to the
  PlanetWRF Model and focus on its applications in
  the Martian environment. This physical scheme
  includes heterogeneous nucleation, homogenous
  nucleation, ion nucleation and CO2 ice particle
  growth. CO2 ice physics is coupled with the dust
  cycle, CO2 cycle and possibly water cycle. With
  followed radiative transfer study and comparison
  with spacecraft data products, we hope to have
  better insight into the history of the climate of
  Mars and its current circulating cycles. Complete
  understanding of the role that CO2 ice clouds
  play in the Martian climate system requires both
  modeling and laboratory work of CO2 ice formation
  processes, which have become two of the most
  urgent tasks in the Mars science community.

• Coupling the microphysics model to PlanetWRF
  Figure 2. Schematic flowchart showing
  the relationships between microphysical
  and atmospheric processes
  involved in modeling the
  nucleation and
  growth/evaporation of ice crystals in
  the planetary atmosphere. Adopted from
  figure 1.1 of Wood, 1999 2.
• PlanetWRF is the atmospheric
  model we use. Radiative transfer
  model,
  sedimentation model are
  currently
  being tested.
• 1D SIMULATIONS
• 1D annual cycle for Latitude 60 ºN. Log normal
  distributed dust with mean radius of 2 microns.
  No sedimentation of aerosols. CO2 ice is not
  radiative active. No direct surface condensation.
• Figure 3. (a) Temperature annual cycle (b)
  CO2 vapor super saturation (c) CO2 ice mass
  mixing ratio
• CO2 is super saturated in the winter. Dust
  particles become condensation nuclei. CO2
  ice particles are formed and then diffuse in
  the atmosphere.
• Figure 4. (a) Dust spectral amount at Ls300
  º (Northern Winter) (b) CO2 ice particle
  spectral amount at Ls300º (c) Surface
  Pressure Annual Cycle
• In the steady state, CO2 ice particles has
  radii of hundreds of microns. Consistent
  with Ivanov and Muhleman, 20014

3D SIMULATIONS
(PlanetWRF)
Figure 5 (upper left). Zonal average of CO2 ice
mass mixing ratio (color) and temperature
(contour) in northern winter. Figure 6 (upper
right). Same as Figure 5 but in southern
winter. Figure 7 (lower right). CO2 ice spatial
distribution and temperature at layer 16 (roughly
1km above the surface ) in southern winter

• PLANETWRF 1
• http//www.planetwrf.com
• Dynamic core
• Dynamics conserve mass and angular momentum to
  high accuracy, highly parallel, large suite of
  physics parameterizations and a modular form,
  uses Arakawa C-grid.
• Nesting capability 1-way or 2-way nesting
  capability
• Rotated pole capability better spatial
  resolution at polar region
• CO2 Microphysics model2,3
• Nucleation JnucF(P, T, qco2, Nnuc, rnuc) m-3
  s-1
• Homogeneous (huge super saturation, less
  favored)
• Ion (less super saturation, poor knowledge of
  ions, less favored)
• Heterogeneous (dust as nuclei, favored)
• Particle growth rate JmF(P, T, qco2, rnuc,
  Qrad) m s-1
• Figure 1. Ice particle growth rate (for given
  size of crystal, given
• pressure and CO2 mass mixing ratio) as a
  function of CO2 super saturation.
  Reproduction of figure 8.7 of Wood, 1999 2.

Cloud heights are consistent with Ivanov and
Muhleman, 2001 4 and Neumann et al. 2003 5

• FUTURE WORK
• Sedimentation scheme
• Coupling with dust cycle
• Radiative active CO2 cloud
• More comparison with data
• Paleoclimate simulation
• The numerical simulations for this research were
  performed on Caltech's Division of Geological and
  Planetary Sciences Dell cluster (CITerra)
• http//aeolis.gps.caltech.edu/wiki

References 1 Richardson MI, Toigo AD, Newman
CE. The Planetary WRF Model A General Purpose,
Local to Global Numerical Model for Planetary
Atmospheric and Climate Dynamics. In preparation
2006 2 Wood SE. Nucleation and growth of CO2
ice crystals in the Martian atmosphere, in Earth
and Space Sciences, University of California, Los
Angeles, Los Angeles, 1999. 3 Maattanen, A., H.
Vehkamaki, A. Lauri, S. Merikallio, J. Kauhanen,
H. Savijarvi, and M. Kulmala, Nucleation studies
in the Martian atmosphere, Journal of Geophysical
Research, 110 (E2), 2005. 4 Ivanov, A.B., and
D.O. Muhleman, Cloud reflection ovservations
Results from the Mars Orbiter Laser Altimeter,
Icarus, 154, 190-206, 2001. 5 Neumann, G.A.,
D.E. Smith, and M.T. Zuber, Two Mars years of
clouds detected by the Mars Orbiter Laser
Altimeter, Journal of Geophysical Research, 108
(E4), 5023-5039, 2003.
Corresponding author. Tel. [phone]
Fax [phone]. Email address
xin_at_gps.caltech.edu (Guo, Xin)