Institute for Climate and Atmospheric Science

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Institute for Climate and Atmospheric
Science SCHOOL OF EARTH AND ENVIRONMENT
Incorporating Mesospheric Metal Chemistry into
NCAR WACCM Model
Wuhu Feng1,2, John Plane2, Martyn Chipperfield1 1
IAS, School of Earth and Environment, University
of Leeds 2 School of Chemistry, University of
Leeds
Acknowledgments Dan Marsh3, Diego Janches4,
Sandip Dhomse1, Sarah Broadley2 3 Atmospheric
Chemistry Division, NCAR, USA 4 Northwest
Research Associates, Boulder, USA
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OUTLINE

• Motivation
• Description of WACCM CCM
• Metal Chemistry in Mesosphere
• Preliminary Results
• Summary
• Future work

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Atmospheric layers
Thermosphere
Mesopause
Meteoric Metals (Na, Fe, Mg, Ca, etc.) Layer
Mesosphere
Stratopause
Stratospheric Ozone Layer
Stratosphere
Tropopause
Troposphere
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Why We Care About Mesosphere

• Studying Climate Change also needs to consider
  Mesopshere
• (impact of climate change by interacting with
  Stratosphere
• and Thermosphere?)
• Weather forecast has significant improved by
  extension of
• ECMWF from Stratosphere to Mesosphere
• Observations shows pronounced cooling in
  Mesosphere
• ( 2-10K/decade) (Beig et al., 2003)
• Mesosphere is poorly understood
• 50 tonnes of meteors enters the
  atmosphere/day(Plane, 2003)
• Mesospheric metal layers should be useful for
  testing the
• model(s) chemical and dynamics processes

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Mesospheric Temperature Trend
Beig et al. (Rev. Geophys., 2003)
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• Whole Atmosphere Community Climate Model uses
  the software
• framework of the NCAR CCSM
• Atmospheric layers coupling,processes,climate
  variability/change
• s-p coordinates (66 levels) from surface up to
  140 Km
• (1.5 km in LS and 3 km in MLT)
• 4ox5o and 1.9ox2o horizontal resolution
• Detailed dynamics/physics in the
  Troposphere/Stratosphere/
• Mesosphere/Thermosphere (Finite-Volume
  dynamics Core)
• Detailed Chemical processes in the atmosphere
  (using NCAR
• MOZART-3 chemistry package (Ox, HOx,ClOx, BrOx
  etc.))
• Ion Chemistry and other parameters

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WACCM Tracer Transport Scheme
Physics
FV No explicit diffusion (besides divergence
damping)
From Christiane Jablonowski
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WACCM Chemistry
13 Additional Surface Source Gases (NHMCs)
CH3OH, C2H6, C2H4, C2H5OH, CH3CHO, C3H8, C3H6,
CH3COCH3, C4H8, C4H8O, C5H8, C5H12, C7H8,
C10H16 45 Additional radical species Detailed 3D
emission inventories of natural and anthropogenic
surface sources Dry/Wet deposition of soluble
species Lightning and Aircraft production of NOx
12 Heterogeneous processes, 71 photolysis
reactions, 183 gas phase reactions No Metal
Chemistry (e.g., Na, Fe, Ca, Mg, K etc. ) in the
standard WACCM model
Long-lived Species (19 species) Misc CO2,
CO, CH4, H2O, N2O, H2, O2 CFCs CCl4, CFC-11,
CFC-12, CFC-113 HCFCs HCFC-22
Chlorocarbons CH3Cl, CH3CCl3, Bromocarbons
CH3Br Halons H-1211, H-1301 Constant
Species N2 , N(2D) Short-lived Species
(31-species) OX O3, O, O(1D) NOX N, NO,
NO2, NO3, N2O5, HNO3, HO2NO2 ClOX Cl, ClO,
Cl2O2, OClO, HOCl, HCl, ClONO2, Cl2 BrOX Br,
BrO, HOBr, HBr, BrCl, BrONO2 HOX H, OH, HO2,
H2O2 HC Species CH2O, CH3O2, CH3OOH
Updated from R.G. Robel, D. Kinnison (NCAR)
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Sodium Chemistry in the Upper Atmosphere

1. Ionization of Na by charge transfer with the
   ambient ions in the lower E region.
2. The Na layer appears in the upper mesosphere due
   to the dramatic increase in atomic oxygen and
   hydrogen above 80 km which convert NaHCO3 back to
   Na
3. Na layer is sensitive to perturbation in the odd
   oxygen photochemistry and plasma density

Ion Chemistry
Plane (ACP, 2004)
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Iron Chemistry in the Upper Atmosphere

1. Different between metal chemistry (e.g, Fe, Mg,
   Ca) in MLT.
2. Fe is not chemically inert
3. The removal of Fe metal atoms involves
   oxidation by O3 to form neutral metal oxides,
   followed by recombination with O2, CO2, or H2O to
   form the trioxide, carbonate, or dihydroxide,
   respectively
4. FeOH is the major iron reservoir below the peak
   of Fe layer

Plane (Chem. Rev., 2003)
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Metal Source in the MLT

• The Major source of Metals (Na, Fe, Ca, Mg, Si,
  Al, Ti, K) in the MLT is the ablation of Sporadic
  Meteoroid particles
• Large uncertainty in the daily meteoroids
  entering the atmosphere (7-240 tons per day)
  (Plane, 2004)
• Meteoroid particles undergo frictional heating
  at high velocity (11-72 km/s) when it collides
  with atmospheric molecules causing metallic
  species to ablate from the meteoroid surface
• Meteoric input function is therefore important
  to model the Metal in the Mesosphere
• Distributions of the particles vary with mass,
  entry velocity and solar zenith angle

Pictures from internet
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An example of ablation profiles

• Different metals are released at different
  altitudes
• The deposition for the most probable meteoroid
  varies with mass, SZA and entry velocity

The ablation profiles from 1D CAMOD
model(SZA35o,V21 km/s, mass4µg).
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Na Injection Rate
Three different Na injection rates used in WACCM
for testing the model performance Na flux is
2100 atom cm-2s-1
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Na Total Column Density Comparison

• Constructing Mesospheric Na reference by
  combination of recent satellite observations (ie.
  OSIRIS/Odin) and ground-based lidar measurements
  by Plane (2010).
• Successful input Na chemistry in WACCM model
• Detailed MIF needed though there is good
  agreement between observations and model

COSPAR reference Atmosphere (Plane,2010)
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Meteoric Input Function (MIF)
MIF of individual element by integration of
meteoroid particles over ranges of mass, velocity
and SZA. Too small flux needed by WACCM?
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Sodium (Na) Comparison
WACCM with Na chemistry underestimates the
observed Na profiles, due to much lower Na flux
input into the model(?)
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Iron (Fe) Comparison
WACCM with Fe chemistry underestimates the
observed Fe profiles but fails to capture the
seasonal variation due to (WACCM) T problem?
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Temperature Comparison

• WACCM

Gardner et al. (To be submitted JGR)
WACCM fails to capture the observed T seasonal
variation
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Temperature Comparison
Metal chemistry in the upper atmosphere seems to
affect the atmospheric dynamics in WACCM
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Temperature Difference
Metal chemistry in the upper atmosphere seems to
affect the atmospheric dynamics in WACCM
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Summary and Conclusion

• Successful adding Mesospheric Metal(s)
  Chemistry into a 3D NCAR WACCM model
• The modelled metal in the MLT is very sensitive
  to the meteoroid injection rate
• Metal chemistry in the upper atmosphere seems to
  affect the atmospheric dynamics in WACCM (is it
  real or due to the model internal variability?)

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Further Work

• Investigate the MIF used in WACCM
• Nudged WACCM and higher vertical resolution (
  1km) run
• Need to do similar for other metals (e.g., Ca,
  Mg etc)
• Long-term simulations, compare with available
  observations
• Needs more mesospheric metals observations from
  Satellites /lidar measurements (SCIAMACHY, ODIN
  etc) to compare with WACCM which we have included
  mesospheric Metal chemistry