1. Oxygen Isotope Anomaly found in water vapor from Alert, Canada Y. Lin, R. N. Clayton, L. Huang, N. Nakamura, J. R. Lyons 2012 Apr.25, Vienna, EGU

2. Mass-dependent fractionation (MDF) (1 +  17 O/1000) = (1 +  18 O/1000)   17 O =  18 O,  ≈ 0.52 (e.g. Clayton, 1993)  17 O =  17 O –  18 O Non-mass-dependent (NMD) fractionation  17 O = 10 3 ln(1+  17 O) –  10 3 ln(1+  18 O), approximated by

3. Terrestrial fractionation line (TFL) (Thiemens, 1999)

4. 1000ln(δ 18 O/1000 +1) (‰) 1000ln(δ 17 O/1000 +1) (‰) NMD effect in ozone and other gases (e.g. Mauersberger et al., 1993; Thiemens et al., 1995)

5. 1000ln(δ 18 O/1000 +1) (‰) 1000ln(δ 17 O/1000 +1) (‰) NMD effect in ozone formation and dissociation in the lab （ e.g. Heidenreich and Thiemens, 1983)

6. Modeled Δ 17 O in stratospheric water （ Zahn et al., 2006)

7. Δ 17 O (‰) Δ 17 O in the lowermost stratospheric water (Franz and Röckmann, 2005)

8. Brewer-Dobson Circulation (e.g. Hintsa et al., 1998)

9. “Age”of stratospheric air (Rosenlof et al., 1995)

10. Water Samples  2002−2005 ： 25 Alert water vapor (provide by Environment Canada)  1930−1996 ： 7 Ice core samples from Dasuopu Glacier, Chinese Himalayas (Provided by Lonnie Thompson)  2003−2005 ： 27 Chicago local precipitation (CLP)

11. Collection of water vapor at Alert station

12. 2BrF 5 + 2H 2 O  2BrF 3 + 4HF + O 2 Fluorination of water

13. Delta E IRMS

14. Equilibrium fractionation line of CLP Results

16. Stacked seasonal variation of Δ 17 O in water vapor samples from Alert, Canada

17. Schematic of  17 O transport and mixing in the Earth’s atmosphere in the northern hemisphere

18. Stratospheric water has averageΔ 17 O=40‰, only an order of magnitude estimation due to the simplicity of the model

19. Alert snow Δ 17 O=43±5ppm （ 2σ error ）, rel. VSMOW

20. Conclusions  Chicago local precipitation defined λ MDF (H 2 O)=0.5292±0.0030 (2σ observed scatter).  Δ 17 O value of 76±16 ppm (2σ standard error) was observed in the water vapor samples from Alert, Canada. Stacked seasonal trend shows a maximum in late spring and a minimum in the fall.  The positive anomaly presumably originating from stratospheric ozone, was then transported downward into the troposphere and was significantly diluted by lateral mixing with low-latitude air with negligible Δ 17 O.

21.  6 Alert snow samples analyzed at LSCE, France has Δ 17 O=43±5 ppm relative to VSMOW. We think the difference between Alert snow and Alert water vapor is due to inter- laboratory difference in analytical techniques.  Average Δ 17 O for stratospheric water of ~40‰ was calculated using a steady-state box model, however this is only an order of magnitude estimation. The value is somewhat higher than the chemical model predictions of 0−30 ‰ for stratospheric water vapor [Lyons, 2003; Zahn et al., 2006], and is much greater than the observation of <2‰ for the lower stratosphere [Franz and Röckmann, 2005]. We suspect that the sampled air in the latter study had possibly exchanged with tropospheric air.  Future work is to measure Δ 17 O in Alert water vapor and snow samples collected on shorter and more regular period, and to measure Δ 17 O of stratospheric water.

22. Acknowledgments  The authors sincerely thank personnel from Environment Canada for water vapor sample collection, for providing us the temperature, pressure, relative humidity, and precipitation data.  Contribution of ice core samples by Lonnie G. Thompson (The Ohio State University) and preparation by Mary E. Davis  Robert N. Clayton, Frank M. Richter, Andrew M. Davis, Lawrence Grossman from the University of Chicago  Measurement of Alert snow samples by Amaelle Landais  This project was funded by the U.S. National Science Foundation (EAR 0439925).