Tropospheric ozone climatology at extratropical latitudes

1. Tropospheric ozone climatology at extratropicallatitudes O.A. Tarasova(1), A.M. Zvyagintsev(2) , G. Kakajanova(2) , I.N. Kuznetsova(3) Faculty of Physics, Lomonosov Moscow State University, Moscow, Russia OTarasova@yandex.ru Central Aerological Observatory of Russian HydrometeorologicalCenter, Dolgoprudny, Moscow region, Russia, Hydrometeorological State Research Centerof Russia, Moscow, Russia The work is carried out in the frames of ACCENT project EGU General Assembly 2006, Vienna

2. “What do we know about tropospheric ozone?” or Objectives • The spring maximum is a Northern Hemispheric phenomenon. It occurs widely across mid-latitudes in the Northern Hemisphere. Its nature is still unclear • The phenomenon occurs with different timing and magnitude in the boundary layer and lower free troposphere as compared to the upper troposphere. Is it trueout of the mid-latitudes of the Northern Hemisphere? • There are apparent latitude/longitude gradients in the shape of the seasonal cycle over Europe. On the western edge of Europe there are sites with a spring maximum/summer minimum. This is followed by a band of sites with a spring time maximum followed by a broad decrease in ozone towards autumn. Finally, in the interior of Europe measurement sites display a broad summer maximum. Can we say anything about global gradients? • Diurnal cycle is characterized by afternoon maximum at non-elevated sites and at night concentration maximum at the elevated ones. Can it help us to interpret observed seasonality? • By the ozone sondes measurements in the north Pacific it was shown that in general the prominent spring maximum is observed throughout the troposphere being tied to the jet stream. Is it “local” phenomenon? Oltmans, S. J., et al. (2004), Tropospheric ozone over the North Pacific from ozonesonde observations, J. Geophys. Res.,109, D15S01, doi:10.1029/2003JD003466. Monks, P.S, A review of the observations and origins of the spring ozone maximum, Atmospheric Environment 34 (2000) 3545-3561

3. Ozone measurements networks(long time series)

4. Approach used • Long-term measurements are selected • Mean seasonal cycle with 1 hour resolution is calculated • Obtained seasonal cycles are classified by K-means clusters • Center of clusters are analyzed • Amplitude of seasonal/diurnal variations is estimated for each cluster for each hour/month.

5. EMEP network: 5 clusters results

6. EMEP network: 5 clusters results Rural and semi-polluted Semi-elevated Clean (remote) High-mountain Ispra

7. Clusters of sites according to seasonal-diurnal variability shape (EMEP+WDCGG)

8. EMEP+WDCGG network: Seasonal – diurnal cycles clustering Clean sites – spring maximum

9. EMEP+WDCGG network: Seasonal – diurnal cycles clustering Semi-polluted and semi-elevated – double maximum with spring dominating

10. EMEP+WDCGG network: Seasonal – diurnal cycles clustering Rural – spring maximum and autumn minimum with bigger amplitude than for clean group

11. EMEP+WDCGG network: Seasonal – diurnal cycles clustering Elevated – double maximum with spring dominating and nigh diurnal maximum

12. EMEP+WDCGG network: Seasonal – diurnal cycles clustering Polluted – double maximum with summer dominating

13. Shift of seasonality for the sites with double maximum

14. Surface ozone seasonal series in the Southern hemisphere

15. Ozone sondes launch-sites

16. Seasonal – altitudinal distribution of ozone concentration (ozonesondes – WOUDC) 67N-83N 53N-59N

17. Seasonal – altitudinal distribution of ozone concentration (ozonesondes – WOUDC) 48N-53N 40N-47N

18. Seasonal – altitudinal distribution of ozone concentration (ozonesondes – WOUDC) 36N-38N 19N-32N

19. Seasonal – altitudinal distribution of ozone concentration (ozonesondes – WOUDC) Southern Hemisphere Impact of the spring Antarctic ozone anomaly is observed at all Antarctica station to a greater or lesser extent

20. Conclusions • In general ozone concentration in the troposphere is lower in the Southern hemisphere BUT it has similar features as in the Northern hemisphere. • Ozone seasonal cycle is observed between winter and summer in both hemispheres. • At the high and mid latitudes of the both hemispheres seasonal maximum of the surface ozone is observed in winter – beginning of spring and its position in time does not depend on the local time. It is observed thought whole troposphere. Spring maximum is likely to have dynamical nature • Moving to the South, time of the maximum shifts to summer months and the structure of the seasonal variability gets more complicated. As summer maximum is observed only for daily ozone (2 months earlier than for night seasonal maximum) and only in the low troposphere it is likely to have a photochemical nature. • There are several distinct seasonal-diurnal structures of the surface ozone variability with spring, spring-summer and summer seasonal maximum. It is difficult to make any conclusion about global spatial gradients of the seasonal-diurnal variability shape. Only slight latitudinal shift of variability amplitudes is observed. • Spring ozone anomaly impacts the seasonality observed at the sonding sites in Antarctica.

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