1 Planetary Wave-Induced Ozone Heating and its Effect on Troposphere-Stratosphere Communication Terry Nathan Atmospheric Science Program University of California, Davis Eugene Cordero Department of Meteorology San Jose State University John Albers Atmospheric Science Program University of California, Davis OUTLINE Motivation / Goal Model and Equations Conceptual Framework “New” Pathway for Communication Ozone-Modified “Downward Control” Ozone-Modified Wave-Mean Flow Interaction Conclusions

2 Motivation / Goal Motivation Goal Stratosphere-troposphere communication is an integral part of the climate system. Essential to this communication is a faithful representation of the interactions between dynamics, radiation and chemistry in the stratosphere. Yet it remains unclear how natural and human-caused changes in these interactions are communicated to the troposphere. eedback mechanism pathway f To determine to what extent planetary wave-induced ozone heating serves as a feedback mechanism and pathway for amplifying and communicating natural and human-caused changes in stratospheric ozone to the troposphere.

3 Wave-Induced Ozone Heating Studies StudyWave TypeRemarks Leovy (1966)inertio-gravity wave radiative-photochemical destabilization of inertio-gravity waves near the mesopause Lindzen (1966)baroclinic wave radiative-photochemical destabilization of a baroclinic zonal current to baroclinic waves in the mesosphere (2-level model) Zhu and Holton (1986, JAS)inertio-gravity wave significant radiative-photochemical damping of inertio-gravity waves in the stratosphere and lower to mid mesosphere Nathan (1989, JAS)free Rossby wave analytical study showing how wave-induced ozone heating can alter the damping rates of free Rossby waves Nathan and Li (1991, JAS)free Rossby wave numerical study showing how wave-induced ozone heating can alter the damping rates of free Rossby waves Nathan et al. (1994, GRL)free Rossby wave wave-induced ozone heating destabilizes traveling waves during summer Echols and Nathan (1996, JAS)Kelvin wave wave-induced ozone heating modifies the wave fluxes that drive the semi-annual oscillation Cordero and Nathan (2000, JAS) Kelvin and Rossby-gravity waves wave-induced ozone heating modifies the wave fluxes that drive the quasi-biennial oscillation Xu, Smith, Brasseur (2001)inertio-gravity wave confirmed Leovy’s (1966) study using a more sophisticated radiative-photochemical model Cordero and Nathan (2005, GRL) Kelvin and Rossby-gravity waves wave-induced ozone heating provides a pathway for communicating the effects of solar variability to the quasi- biennial oscillation Nathan and Cordero (2007; JGR)forced Rossby wave derivation of a refractive index for vertically propagating planetary waves that accounts for wave-induced ozone heating Gabriel et al. (2007; GRL)GCM MEACHAM5 “… important influence of ozone-dynamics interaction…” “…shift of upward and eastward directed stationary wave train…”

4 Model (Nathan and Li 1991, JAS; Cordero and Nathan 2007, JGR) Dynamics Radiative-Photochemical Quasigeostrophic Bottom forcing Linear mechanistic Analytical (WKB) Wave-Mean Flow Interaction M echanistic: Holton-Mass (1976) with ozone transport and photochemistry Newtonian Cooling Ozone transport Ozone photochemistry Solar spectral irradiance accounted for in ozone production / destruction Catalytic loss processes involving hydrogen, nitrogen and chlorine compounds are parameterized by adjusting pure oxygen reaction rate (Hartman 1978) Ozone shielding effect

5 Governing Equations Perturbation Equations Zonal-Mean Equations HEATING/ COOLING PRODUCTION/ DESTRUCTION OZONE QGPVE ZONAL MEAN FLOW Plus Mean-Meridional Circulation Equation

6 m 2 <0 m 2= 0 m 2> 0 EVANESCENT PROPAGATING REGION = Complex Refractive Index * Conceptual Framework REFLECTING SURFACE * Nathan, T. R., and E. C. Cordero, 2007: An ozone-modified refractive index for vertically propagating planetary waves. J. Geophysical Research - Atmospheres, 112, D02105, doi: /2006JD Cordero, E., and T. R. Nathan, 2005: A new pathway for communicating the 11-year solar cycle signal to the QBO. Geophys. Res. Lett., 32, No. 18, L18805, /2005GL Re (m) ~ propagation Im (m) ~ attenuation

7 CIRCULATION AND CLIMATE (MEAN FIELDS) REFRACTIVE INDEX PWD (WAVE FIELDS) REFRACTIVE INDEX PWD “TRADITIONAL” PATHWAY INCOMPLETE VIEW Zonal-Mean Pathway “NEW” PATHWAY MORE COMPLETE VIEW Wave-Ozone Pathway plus Zonal-Mean Pathway External Forcing (e.g., solar CFCs etc ) “New” Pathway for Ozone-Modulated Troposphere- Stratosphere Communication

8 Wave-Ozone Pathway The planetary wave-induced ozone heating (wave-ozone feedback process) pivots on wave-like perturbations in the wind and temperature fields producing wave-like perturbations in the ozone field. Vertically Propagating Wave Wave Perturbation in Ozone

9 The phasing and structure of the wind, temperature and ozone fields -- which are coupled to each other as well as to the background distributions of wind, temperature and ozone -- directly affect wave transience and wave dissipation, processes vital to the driving of the zonal-mean circulation. Any perturbation to the wave-ozone feedbacks, natural or human-caused, will be imparted to the zonal-mean field. PHASE DIFFERENCE T’ O’

10 Ozone-Modified Downward Control Adapted from Holton 2004 Residual Vertical Velocity “Downward Control” To what extent is the divergence of Eliassen-Palm flux (i.e., PWD) affected by the planetary wave induced ozone heating? “Downward influence from a radiative perturbation can only arise through changes in reflection and meridional propagation of planetary waves.” Shepard and Shaw (2004; JAS)

11 WKB Solution for EP-Flux Divergence Ozone-Modified Vertical Wavenumber (Refractive Index) Ozone-Modified Planetary Wave Drag

12 Ozone-Modified Propagation and Attenuation “CLASSIC” REFRACTIVE INDEX LOWER STRATOSPHERE – DYNAMICAL CONTROL UPPER STRATOSPHERE – PHOTOCHEMICAL CONTROL

13 Results SOUTHNORTH Zonal Wave 2 Based on climatological distributions of wind, temperature and ozone (winter). No Ozone With Ozone Normalized Vertical Structure ofLatitude-Height Cross-Section of Reflecting Surface 10-15% decrease in troposphere Factor of 2 increase in stratosphere

14 Holton-Mass Model with Wave-Induced Ozone Heating Holton and Mass (1976) -- No Ozone Feedbacks Current Study – With Ozone Feedbacks Mean Zonal Wind (m z=15 km Mean Zonal Wind (m z=50 km Mean Zonal Wind (m z=15 km Mean Zonal Wind (m z=50 km Holton and Mass (1976) -- No Ozone Feedbacks Current Study – With Ozone Feedbacks Time (days) Wave 2, h b = 270 m Wave 1, h b = 50 m

15 Conclusions  The combined effects of planetary wave-induced ozone heating, “downward control,” and wave reflection may communicate – and amplify – both natural and human-caused perturbations in stratospheric ozone to the troposphere.  A more complete pathway for communicating solar cycle- induced changes in stratospheric ozone to the climate system is proposed. The pathway incorporates the effects of planetary wave- induced ozone heating. External Ozone Forcing

16 Sun-Climate Focused Science Team TEAM MEMBERS Terry Nathan Eugene Cordero Linton Floyd Rolando Garcia Lon Hood Charles Jackman Judith Lean John McCormack Jeff Morrill Cora Randall David Rind Sponsored by NASA’s Living with a Star Program “ S ENSITIVITY of R EGIONAL and G LOBAL C LIMATE to S OLAR F ORCING ”