1 Interannual Variability in Stratospheric Ozone Xun Jiang Advisor: Yuk L. Yung Department of Environmental Science and Engineering California Institute of Technology 11/8/2006

2 Overview Ozone: Observations and Models  Tropics: QBO, QBO-AB, Solar Cycle, ENSO, MJO  High Latitudes: Annular Modes

3 Data and Models Data  Merged O 3 Data (MOD) [McPeters et al., 1996]  Assimilated O 3 from European Centre for Medium-Range Weather Forecasts (ECMWF) [Uppala et al., 2005] Models  2-D Caltech/JPL Chemistry and Transport Model  2-D Interactive Chemistry and Transport Model  3-D GEOS-4 Chemistry-Climate Model

4 Principal Component Analysis (PCA) (N timesteps  M stations ) Covariance Matrix ( M  M ) EOFs ( e, Eigenvectors of C ): modes of spatial pattern PCs ( p, ): time-dependent amplitudes of the EOFs Eigenvalue: the fraction of variance captured by each EOF The original data can be represented by To make EOF patterns have dimensional units. We multiply each EOF by the square root of their associated eigenvalue, and divide each PC by this value.

5 Tropical IAV in the Column Ozone from MOD [Camp et al., 2003] EOFs PCs Amplitude Spectra 42% Cumul. Var. QBO Decadal R=0.80

6 42% 75% 90% EOFs PCs Amplitude Spectra Cumul. Var. Tropical IAV in the Column Ozone from MOD [Camp et al., 2003] 93% R=0.80 R=0.73 R=0.71

7 Tropical IAV in the Column Ozone from Model [Jiang et al., 2004] Mean meridional circulation and eddy mixing coefficients derived from the NCEP/DOE Reanalysis 2 (NCEP2). The first realistic simulation of the QBO and QBO- Annual Beat (QBO-AB) in column ozone from 1979 to The model ozone results for QBO and QBO-AB are compared to the signals obtained by the zonal mean MOD observations.

8 MOD 2D CTM Composite of Column Ozone from 1979 to 2002 Tropical IAV in the Column Ozone from Model [Jiang et al., 2004]

9 Tropical IAV in the Column Ozone from Model [Jiang et al., 2004] Latitude distribution of ozone anomaly MOD 2D CTM DU

10 74% EOFsPCsPower Spectra Cumul. Var. 85% Ozone PCA: 2D CTM and Zonal MOD [ Jiang et al., 2004] Tropical IAV in the Column Ozone from Model QBO-AB QBO Model (Solid) & MOD (Dash) R=0.87 R=0.5

11 Quasi-biennial Oscillation-Annual Beat of Ozone [Jiang et al., 2005] An idealized 2-D chemistry and transport model is used to investigate the spatial patterns and propagation the QBO-annual beat (QBO-AB) signal in ozone in the tropics and subtropics An extended EOF analysis is used to study the propagation of QBO and QBO-AB. The model results are compared to those from the Merged Ozone Data (MOD).

12 I: Model: Fully interactive model Comprehensive treatment of stratospheric chemistry The QBO is produced by the parameterization for the deposition of Kelvin and Rossby-gravity wave momentum in the tropical zonal wind. II: Merged Ozone Volume Mixing Ratio Data Model Description and Data

13 Propagation of QBO and QBO-AB (Model) PC 1  EEOF 1 + PC 2  EEOF 2 at equator PC 3  EEOF 3 + PC 4  EEOF 4 at 12.5  N

14 Propagation of QBO and QBO-AB (Data) PC 1  EEOF 1 + PC 2  EEOF 2 at equator PC 3  EEOF 3 + PC 4  EEOF 4 at 12.5  N

15

16 High Latitude IAV of Combined Column O 3 in NH 1st 30.4% Cor. Coeff. 0.53

year Signal in the Arosa Ozone Arosa (46  N, 9  E) column ozone time series (Aug ~ Dec. 2002) Signals in Spectra: 3.5 years, QBO-AB, QBO

18 1st High Latitude IAV of Combined Column O 3 in SH 43.9% Cor. Coeff. 0.45

19 Model  Chemistry module on-line in the general circulation model [Douglass et al., 2003; Stolarski et al., 2006a; Bloom et al., 2005]  Sea surface temperature and sea ice are from observations  No solar cycle, volcanic aerosol, and QBO in the model. Leading modes for the model O 3 in the two hemispheres ENSO signals in TOMS and model O 3 Comparison with a 3-D Chemistry-Climate Model

20 Leading Mode in NH 31.8% Data Model 30.4%

21 Leading Mode in SH 59.5% Data Model 43.9%

22 ENSO in TOMS and 3-D Chemistry-Climate Model TOMS Model

23 PC timeseries of O 3 in Tropics Cor. Coeff TOMS Model 0.53

24 MJO in GEOS-chem Model

25 MJO in GEOS-chem Model

26 Conclusions The 2-D CTM provides realistic simulations of the IAV of ozone in the tropics. The QBO and QBO-Annual Beat are well captured in the Catech/JPL model. An extended EOF analysis reveals the characteristic pattern of the downward propagation of QBO and upward propagation of QBO-AB, which is simulated well by a 2-D interactive CTM. In the high latitudes, first modes are nearly zonally symmetric and represent the connections to the Annular Modes and the Quasi-Biennial Oscillation. 3-D GEOS-4 chemistry-climate model can simulate the ozone trend reasonably well in both hemispheres. Model cannot simulate the low- frequency oscillations well. 3-D Model captures ENSO signal well in the tropics. Some discrepancies for the model ENSO signal in the SH.