1. The origin of stratospheric ozone in sensitivity studies with EMAC-FUB EGU – European Geosciences Union General Assembly 2011 Vienna S. Meul 1), S. Oberländer 1), A. Kerschbaumer 1), U. Langematz 1), V. Grewe 2) 1) FU Berlin 2) DLR, Oberpfaffenhofen

2. 2 Motivation The ozone distribution is determined by local production, lossand transport Analyses of the present- day chemical and dynamical mechanisms Information of the O 3 origin offer a new approach for studying the transport patterns and the chemistry Study of the ‚drivers‘ of future ozone changes in the stratosphere

3. 3 Model setup - version 1.7 - horizontal resolution: 2.8°x2.8° (T42) - vertical resolution: 39 levels (model top: 0.01 hPa) - shortwave radiation parameterisation: FUBRad (EMAC-FUB) ( Nissen et al., 2007 ) - prescribed sea-surface-temperatures (SSTs) and sea-ice- concentrations (SIC) (modelled, MPI-OM) - ozone origin diagnostic ( Grewe, 2006 ) Chemistry-Climate Model ECHAM5/MESSy Atmospheric Chemistry (EMAC) (Jöckel et al., 2006): Time-slice experiment (20 years) for the year 2000 (GHGs, ODSs, mean SSTs/SICs of the period 1995-2004, solar mean)

4. 4 This diagnostic tool allows the identification of the ozone origin at each grid point in the atmosphere (at each timestep) Method: 1. Definition of n ozone production (= origin) regions in the model domain (n=19) tropopause Ozone production regions 1000 10 1 0.03 Pressure [hPa] 60°N60°S lower mesosphere (LM) upper stratosphere (US) middle stratosphere (MS) Method: The ozone origin diagnostic (V. Grewe, 2006; Garny et al., 2011 (submitted))

5. 5 This diagnostic tool allows the identification of the ozone origin at each grid point in the atmosphere (at each timestep) Method: 2. Implementation of an ozone tracer o3 i for each region i (i=1,n) ) transported destroyed (destroyed ozone is produced in region imarked with i (o3 i ) production of o3 i outside region i = 0 and

6. 6 January [%][%] Method: The ozone origin diagnostic Contribution of the ozone origin tracer o3 i to the full ozone field O 3

7. 7 1. Part: Ozone budgets -tropical lower stratosphere -northern polar middle stratosphere

8. Monthly ozone budget of the tropical lower stratosphere positive net production negative transport → ‚export‘ O 3 increase Feb-Aug: net production > export O 3 decrease Oct-Jan: net production < export transport = tendency – (production – loss) net production 8 μmol mol -1 month -1 box-weighted mean

9. Monthly ozone budget of the northern polar middle stratosphere negative net production positive transport → ‚import‘ O 3 increase Sep-Mar: loss < import O 3 decrease Apr-Aug: loss > import transport = tendency – net production 9 μmol mol -1 month -1 box-weighted mean

10. 10 2. Part: The origin of ozone -northern middle stratosphere -comparison of the polar middle stratosphere in the NH and SH

11. 11 The origin of northern middle stratospheric ozone O 3 (black) and o3 i Polar Region (60°-90°N)Mid-latitudes (20°-60°N) ppmv locally produced Seasonal cycle of O 3 driven by the locally produced ozone Seasonal cycle of O 3 as a combination of locally produced and ‚transported‘ ozone

12. 12 o3 i /O 3 *100% Polar Region (60°-90°N) Sum of o3 i minus locally produced O 3 Mid-latitudes (20°-60°N) The origin of northern middle stratospheric ozone July: (70%) NMUS (23%) NPMS (3%) January: (58%) NMUS (24%) TRMS (8%) July: (67%) NPUS (20%) NMMS (12%) January: NMMS (53%) NMUS (29%) (8%) %

13. winter: - larger abundance of mid-lat originating O 3 in the NH - larger abundance of 13 SH Polar Region (60°-90°S)NH Polar Region (60°-90°N) ppmv Jan winter: larger abundance of upper stratospheric polar O 3 in SH locally produced Jul Ozone hole The origin of polar middle stratospheric ozone stronger downward motion inside the vortex SH polar vortex edge less permeable for meridional O 3 transport + weaker meridional circulation

14. 14 Summary & Outlook - Analyses of the ozone budget and ozone origin in the present- day time-slice simulation with the CCM EMAC-FUB - Studies of future changes in ozone transport and chemistry by comparing different sensitivity experiments Future (2045) – Reference (2000) (annual mean) ΔO 3 in ppbv/decade Thank you!