institute for climate and atmospheric science school of earth and environment
DESCRIPTION
Institute for Climate and Atmospheric Science SCHOOL OF EARTH AND ENVIRONMENT. Incorporating Mesospheric Metal Chemistry into NCAR WACCM Model. Wuhu Feng 1,2 , John Plane 2 , Martyn Chipperfield 1 1 IAS, School of Earth and Environment, University of Leeds - PowerPoint PPT PresentationTRANSCRIPT
Institute for Climate and Atmospheric ScienceSCHOOL 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
OUTLINE
• Motivation
• Description of WACCM CCM
• Metal Chemistry in Mesosphere
• Preliminary Results
• Summary
• Future work
Atmospheric layers
Mesosphere
Stratosphere
Troposphere
Thermosphere
Tropopause
Stratopause
Mesopause
StratosphericOzone Layer
MeteoricMetals (Na,Fe, Mg, Ca, etc.) Layer
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
Mesospheric Temperature Trend
Beig et al. (Rev. Geophys., 2003)
• Whole Atmosphere Community Climate Model uses the software
framework of the NCAR CCSM
• Atmospheric layers coupling,processes,climate variability/change
• σ-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……
WACCM Tracer Transport Scheme
FV: No explicit diffusion (besidesdivergence damping)
Physics
From Christiane Jablonowski
WACCM ChemistryLong-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
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
Updated from R.G. Robel, D. Kinnison (NCAR)
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 densityPlane (ACP, 2004)
Ion Chemistry
Iron Chemistry in the Upper Atmosphere
Plane (Chem. Rev., 2003)
1) Different between metal chemistry (e.g, Fe, Mg, Ca) in MLT.
2) Fe+ is not chemically inert3) 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
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
An example of ablation profiles
The ablation profiles from 1D CAMOD model(SZA=35o,V=21 km/s, mass=4µg).
Different metals are released at different altitudes The deposition for the most probable meteoroid varies with mass, SZA and entry velocity
Na Injection Rate
Three different Na injection rates used in WACCM for testing the model performanceNa flux is ~2100 atom cm-2s-1
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)
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?
Sodium (Na) Comparison
WACCM with Na chemistry underestimates the observed Na profiles, due to much lower Na flux input into the model(?)
Iron (Fe) Comparison
WACCM with Fe chemistry underestimates the observed Fe profiles but fails to capture the seasonal variation due to (WACCM) T problem?
•WACCM
Temperature Comparison
WACCM fails to capture the observed T seasonal variation
Gardner et al. (To be submitted JGR)
Temperature Comparison
Metal chemistry in the upper atmosphere seems to affect the atmospheric dynamics in WACCM
Temperature Difference
Metal chemistry in the upper atmosphere seems to affect the atmospheric dynamics in WACCM
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?)
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