1. Status of ongoing Kiruna site Myojeong Gu, Thomas Wagner MPI for Chemistry, Mainz, Germany 1

2. Instrument : Zenith-Sky Differential Optical Absorption Spectroscopy (DOAS) Measurement site: Swedish Institute for Space Physics in Kiruna (Sweden, 68.84°N, 20.41°E) since December of 1996. Measurement site review Zenith Sky DOAS Arctic circle Kiruna, Sweden (68.84°N, 20.41°E)

3. 3

5. Start measurement: December of 1996 Two instrument for Visible (374 – 682nm) and UV (300 – 400nm) spectral range at IRF institute, Kiruna 3 years later, move to inside of optic laboratory in the institute 2013 Jan 28: replacement of detector (Jobinivon spectrometer → IDUS DV 420-ABU) Current instrument updates: 2015 Jun 08 measurement computer OS changing: winXP →win7 Timeline

6. Stratospheric NO 2 VCDs - 1997 8e15 7e15 6e15 5e15 4e15 3e15 2e15 1e15 0

7. Stratospheric NO 2 VCDs - 1998 8e15 7e15 6e15 5e15 4e15 3e15 2e15 1e15 0

8. Stratospheric NO 2 VCDs - 1999 8e15 7e15 6e15 5e15 4e15 3e15 2e15 1e15 0

9. Stratospheric NO 2 VCDs - 2000 8e15 7e15 6e15 5e15 4e15 3e15 2e15 1e15 0

10. Stratospheric NO 2 VCDs - 2001 8e15 7e15 6e15 5e15 4e15 3e15 2e15 1e15 0

11. Stratospheric NO 2 VCDs - 2002 8e15 7e15 6e15 5e15 4e15 3e15 2e15 1e15 0

12. Stratospheric NO 2 VCDs - 2003 8e15 7e15 6e15 5e15 4e15 3e15 2e15 1e15 0

13. Stratospheric NO 2 VCDs - 2004 8e15 7e15 6e15 5e15 4e15 3e15 2e15 1e15 0

14. Stratospheric NO 2 VCDs - 2005 8e15 7e15 6e15 5e15 4e15 3e15 2e15 1e15 0

15. Stratospheric NO 2 VCDs - 2006 8e15 7e15 6e15 5e15 4e15 3e15 2e15 1e15 0

16. Stratospheric NO 2 VCDs - 2009 8e15 7e15 6e15 5e15 4e15 3e15 2e15 1e15 0

17. Stratospheric NO 2 VCDs - 2013 8e15 7e15 6e15 5e15 4e15 3e15 2e15 1e15 0

18. Stratospheric NO 2 VCDs - 2014 8e15 7e15 6e15 5e15 4e15 3e15 2e15 1e15 0

19. Stratospheric NO 2 VCDs - 2015 8e15 7e15 6e15 5e15 4e15 3e15 2e15 1e15 0

20. Stratospheric BrO dSCDs Meas @AM Meas @PM

21. Seasonal mean profile (2002 – 2006) Spring AM (#112)Spring PM (#88) Summer AM (#80) Summer PM (#87) NO 2 conc. [molec/cm 2 ] Spring : March-May Summer: Mid Jun - Aug Retrieved from zenith sky DOAS (blue) Unsmoothed SCIA profile (black) Smoothed SCIA profile (red) a prior (grey) Error bar: standard deviation

22. Comparison of NO 2 partial columns (2005) Relative diff. [%] NO 2 column [molec/cm 2 ] smoothed SCIA – DOAS/DOAS [%] Langley plot method-DOAS/DOAS[%] AMPM

23. Volcanic SO 2 and BrO measurement In September 2014, our measurement observed SO 2 after the Bárðarbunga volcano has been active, which we think that it originates from the volcano. And we also had an enhancement of BrO SCDs which is higher than the stratospheric background. In this work, the situation of observing BrO can be classified into 2 cases: BrO SCDs are enhanced at the same time as the SO 2 SCDs, only BrO SCDs showed up. SO 2 enhancement cases: on Sep.6, DOAS instrument detected the SO 2 plume for the first time at Kiruna and on Sep.10, highly enhanced SO2 was detected.

24. To check the spectral interference O4 was analyzed for 3 different wavelength ranges (350 – 370nm, 355 – 385nm and 336 – 360nm) and found there was no influence by O4 interference. (see Fig.5 O4 graph) Color index(CI) was used to identify clear and cloudy situations. Sep.11: Whole day was covered by continuous clouds (see Fig.5 CI graph: black line indicates clear sky, magenta dot indicates measurement day) and there was optically thick clouds after 12 PM (see Fig.5. normalized flux graph). According to MODIS Cloud Top Pressure and Cloud Optical Thickness (see Fig.6), cloud top height was around 9km in the morning and afternoon and cloud optical depth increased in the afternoon. Sep.26: The increased Cloud Optical Thickness indicates a day with thick clouds and we suppose that clouds in the afternoon (cloud top height: around 8km) had top pressures larger than during the morning (cloud top height: around 4 km). In this work, the situation of observing BrO can be classified into two cases. The first case is that BrO SCDs are enhanced at the same time as the SO 2 SCDs and the second is that only enhanced BrO SCDs showed up. This BrO might be either directly transported from volcanic plume or a small and uniform tropospheric background BrO signal might be enhanced by multiple scattering. Most of measurement days were under cloudy conditions. Enhanced BrO SCDs were coincident with an enhancement of O4, ring, Color Index and spectral intensity.

25. Outlook Analysis of longer period to show the continuation of the time series of the stratospheric BrO and also intend to analyze OClO, O3 (and maybe HCHO).

26. 26 Thank you for your attention!