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