Institute for Climate and Atmospheric Science SCHOOL OF EARTH AND ENVIRONMENT WACCM Modelling Studies at Leeds: Mesospheric Metal Chemistry Wuhu Feng Acknowledgments: John Plane, Martyn Chipperfield, Dan Marsh, Diego Janches, Chester Gardner, Alan Liu, Sandip Dhomse, Erin Dawkins, Martin Langowski, Jonas Hedin, Jörg Gumbel, Joseph Hoeffner,, Barclay Clemesha WUN Workshop, Newfoundland, July 2011

OUTLINE The importance of Mesosphere Description of WACCM CCM Dynamic performance in WACCM Mesospheric Metal Chemistry WACCM metal simulations Summary Future work

Atmospheric layers Mesosphere Stratosphere Troposphere Thermosphere Tropopause Stratopause Mesopause Stratospheric Ozone Layer Meteoric Metals (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)

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

Uncertainties in Interplanetary Dust Particles Courtesy of John Plane

Whole Atmosphere Community Climate Model uses the software framework of the NCAR CESM 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) 4 o x5 o and 1.9 o x2 o 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 (O x, HO x,ClO x, BrO x etc.)) Ion Chemistry and other parameters……

WACCM Chemistry Long-lived Species: (19 species) Misc:CO 2, CO, CH 4, H 2 O, N 2 O, H 2, O 2 CFCs: CCl 4, CFC-11, CFC-12, CFC-113 HCFCs: HCFC-22 Chlorocarbons:CH 3 Cl, CH 3 CCl 3, Bromocarbons: CH 3 Br Halons: H-1211, H-1301 Constant Species:N 2, N( 2 D) Short-lived Species: (31-species) O X : O 3, O, O( 1 D) NO X :N, NO, NO 2, NO 3, N 2 O 5, HNO 3, HO 2 NO 2 ClO X :Cl, ClO, Cl 2 O 2, OClO, HOCl, HCl, ClONO 2, Cl 2 BrO X :Br, BrO, HOBr, HBr, BrCl, BrONO 2 HO X :H, OH, HO 2, H 2 O 2 HC Species:CH 2 O, CH 3 O 2, CH 3 OOH 13 Additional Surface Source Gases (NHMCs): CH 3 OH, C 2 H 6, C 2 H 4, C 2 H 5 OH, CH 3 CHO, C 3 H 8, C 3 H 6, CH 3 COCH 3, C 4 H 8, C 4 H 8 O, C 5 H 8, C 5 H 12, C 7 H 8, C 10 H 16 ~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)

WACCM Vertical Resolution

How good is WACCM dynamics

1) Sensitivity to gravity wave parameters

2) Sensitivity to gravity wave parameters

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 NaHCO 3 back to Na 3) Na layer is sensitive to perturbation in the odd oxygen photochemistry and plasma density Plane (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 inert 3) The removal of Fe metal atoms involves oxidation by O 3 to form neutral metal oxides, followed by recombination with O 2, CO 2, or H 2 O to form the trioxide, carbonate, or dihydroxide, respectively 4) FeOH is the major iron reservoir below the peak of Fe layer

Magnesium Chemistry in MLT Mg is one of the most abundance of Metals in the MLT Unlike other Meteoric metals (Fe, Na, K and Ca), night Mg/Mg+ can be observed by ground-based lidar (laser radar) as they have resonance transitions in the UV region at 285 and 280 nm where light is strongly absorbed by stratospheric. Mg+ is produced from Mg by photoionization and charge transfer with NO+ and O+ (dominant ions in the LT) Mg+/Mg= Na+/Na=0.2 Ca+/Ca=2 Mg+ is not significant depleted relative to other metals in the MLT

Leeds Chemical Ablation Model

Meteoric Input Function (MIF) MIF of individual element by integration of meteoroid particles over ranges of mass, V and SZA. WACCM Na: (Up to 10 tonnes/day)

Meteoric Input Function: Fe and Mg Three different Na injection rates used in WACCM for testing the model performance Na flux is ~2100 atom cm -2 s -1

Na Total Column Density  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

Sodium Profiles Comparison  Successfully reproduces Na layer in WACCM Plane (ACP, 2004)) Na  Na peak is well captured by WACCM  Na density is similar with Plane(2004 )

Comparison with Lidar Measurement  Reproduces Northern mid-latitude mesospheric sodium layer  Modelled Na layer is 1-2 km lower than measurement due to lower mesopause than observation Na

Comparison with Odin/OSIRIS

WACCM Sensitivity Experiments Na

Mesospheric Iron Layer  Similar simulation for Fe but MIF needs to be 4-5 times smaller than Na  PMCs need to be added in WACCM

Sporadic layer of Iron at Davis Station (69S) Courtesy of Joseph Hoeffner (IAP, Germany)

Mg+ and Mg in Jan WACCM simulation

Mg + and Mg Vertical Column Density Correira et al. (2008): GOME measurement WACCM simulation

Solar Proton Event and Mesospheric Mg/Mg+ Scharringhausen (2007)

Summary and Conclusion  WACCM has colder polar temperature and lower mesopause in summer  Sensitivities experiments in WACCM show: 1) The different Prandtl numbers used do not improve the WACCM low mesospause problem although the low Prandtl number has low simulated T in the polar summer; 2) Reducing the amplitude of gravity wave raises up the modelled mesopause.  Successful adding Mesospheric Metals Chemistry (Na, Fe and Mg) into a 3D NCAR WACCM model  WACCM is able to reproduce the observed Na layer but the peak layer is still slight ~2 km lower. Modelled Na density in the SH is ~2 times larger than observation due to too cold summer temperature (10-15 K).  WACCM suggests different MIF input needed: Na (7-10 tonnes/day) and similar amount for Fe and Mg ( tonnes/day)  WACCM has a reasonable simulated peak layers of Mg and Mg+, but the modelled Mg density is much higher than observed

Future Work  Investigate the MIF used in WACCM  Need to do similar for other metals (e.g., Ca etc)  PMCs impact on the mesospheric metals  Investigate the potential impacts of future climate change on mesospheric metal chemistry