SAOZ at Rothera 2. MAX-DOAS at Halley 3. SAOZ spare to Halley Howard Roscoe (BAS), NDACC UV-visible Workshop, BIRA, 3-4 July UV-visible sensors at BAS sites

SAOZ at Rothera: - stratospheric O 3 and NO 2 Old SAOZ-512: Faraday (65S) 1990 to 1995 Rothera (67S) 1996 to 2007 New SAOZ-1024, same grating: Rothera (67S) 2007 to present - 1 year of overlap with old SAOZ UV-visible sensors at BAS sites

SAOZ at Rothera:

1 4 UV-visible sensors at BAS sites Kuttippurath, J., F. Goutail, F. Lefevre, A. Pazmino, J-P. Pommereau, M.P. Chipperfield, W. Feng, H.K. Roscoe, “Estimation of Antarctic ozone loss from Ground-based total column measurements”, Atmos. Chem. Phys. 10, 6569–6581 (2010). 1. SAOZ at Rothera:

1 5 UV-visible sensors at BAS sites Kuttippurath, J., F. Goutail, F. Lefevre, A. Pazmino, J-P. Pommereau, M.P. Chipperfield, W. Feng, H.K. Roscoe, “Estimation of Antarctic ozone loss from Ground-based total column measurements”, Atmos. Chem. Phys. 10, 6569–6581 (2010). Kuttippurath, J., F. Lefevre, J-P. Pommereau, H.K. Roscoe, F. Goutail, A. Pazmino, J. Shanklin, “Antarctic ozone loss in 1989–2010: Evidence for ozone recovery”, submitted, Atm. Chem. Phys. Discuss. 12, (2012). 1. SAOZ at Rothera:

1 6 UV-visible sensors at BAS sites 1. SAOZ at Rothera:

1 7 UV-visible sensors at BAS sites Total vertical NO 2 in Antarctic summer - the 24-hour sunlight means there is no N 2 O 5 - so no hydrolysis of N 2 O 5 on stratospheric aerosol - so NOy / NO 2 is much less dependent on background aerosol (between volcanoes) NOy calculated from the NO 2 by SLIMCAT stacked box model - the model is unreliable in 1991 & 1992, due to Pinatubo aerosol - the NOy/NO 2 ratio is robust to model settings little overall trend large inter-annual variability maximum in 2000/2001

1 8 UV-visible sensors at BAS sites Multiple regression of NOy vs solar, QBO, ENSO & linear-trend (Cook & Roscoe 2009) Reconstruction accounts for >1/3 of the variance - accounts for ~1/3 of the maximum in 2000/01 - reconstructions are offset by arbitrary amounts - residuals show a cycle amplitude > 15% period > 17 years Remaining linear trend = 1.1  3.5 %/decade

1 9 UV-visible sensors at BAS sites Box model of Brewer Dobson circulation (Cook & Roscoe 2012) Analytic solution in steady state: with N 2 O source, slowing BDC by 40% increases NOy by 39% (ratio =1.03) Trend in speed of BDC = –(NOy trend –tropN 2 O trend + N 2 OreactionRate trend) x1.03 = – (+1.1 ± 3.5 – ) x 1.03 %/decade = –1.1 ± 3.5 %/decade (1-sigma)

SAOZ at Rothera: Old SAOZ-512; new SAOZ-1024, same grating: - 1 year of overlap with old SAOZ UV-visible sensors at BAS sites

SAOZ at Rothera: Old SAOZ-512; new SAOZ-1024, same grating: - 1 year of overlap with old SAOZ UV-visible sensors at BAS sites

SAOZ at Rothera: Old SAOZ-512; new SAOZ-1024, same grating: - 1 year of overlap with old SAOZ UV-visible sensors at BAS sites

SAOZ at Rothera: Old SAOZ-512; new SAOZ-1024, same grating: - 1 year of overlap with old SAOZ UV-visible sensors at BAS sites

1 14 UV-visible sensors at BAS sites 1. SAOZ at Rothera

MAX-DOAS at Halley - tropospheric BrO and IO Mini-MAX-DOAS: Halley (76S) Jan 2007 to Feb 2008 Weddell Sea (52-77 S) Jan-March 2009 Rothera (67S) Jan and Feb 2010 Dome C (76S) Jan and Feb 2011 Avantes spectrometer for BrO & IO: Halley (76S) Jan 2012 to present UV-visible sensors at BAS sites

MAX-DOAS at Halley - tropospheric BrO and IO UV-visible sensors at BAS sites

1 17 To be submitted to Atm. Meas. Tech. (2012). Resolution of an important discrepancy between remote and in-situ measurements of tropospheric BrO during Antarctic enhancements. H.K. Roscoe 1, N. Brough 1, A.E. Jones 1, F. Wittrock 2, A. Richter 2, M. Van Roozendael 3, F. Hendrick 3 UV-visible sensors at BAS sites

1 18 To be submitted to Atm. Meas. Tech. (2012). Resolution of an important discrepancy between remote and in-situ measurements of tropospheric BrO during Antarctic enhancements. H.K. Roscoe 1, N. Brough 1, A.E. Jones 1, F. Wittrock 2, A. Richter 2, M. Van Roozendael 3, F. Hendrick 3 UV-visible sensors at BAS sites

1 19 To be submitted to Atm. Meas. Tech. (2012). Resolution of an important discrepancy between remote and in-situ measurements of tropospheric BrO during Antarctic enhancements. H.K. Roscoe 1, N. Brough 1, A.E. Jones 1, F. Wittrock 2, A. Richter 2, M. Van Roozendael 3, F. Hendrick 3 UV-visible sensors at BAS sites

1 20 To be submitted to Atm. Meas. Tech. (2012). Resolution of an important discrepancy between remote and in-situ measurements of tropospheric BrO during Antarctic enhancements. H.K. Roscoe 1, N. Brough 1, A.E. Jones 1, F. Wittrock 2, A. Richter 2, M. Van Roozendael 3, F. Hendrick 3 UV-visible sensors at BAS sites

1 21 To be submitted to Atm. Meas. Tech. (2012). Resolution of an important discrepancy between remote and in-situ measurements of tropospheric BrO during Antarctic enhancements. H.K. Roscoe 1, N. Brough 1, A.E. Jones 1, F. Wittrock 2, A. Richter 2, M. Van Roozendael 3, F. Hendrick 3 UV-visible sensors at BAS sites

MAX-DOAS at Halley - tropospheric BrO and IO UV-visible sensors at BAS sites

MAX-DOAS at Halley - tropospheric BrO and IO UV-visible sensors at BAS sites Udo comment at ACPD: From our experience, scattered light measurements by an Ocean Optics 2000 spectrometer in a MiniDOAS setup results in residual structures with an RMS of at least 5 x The peak cross section of IO amounts to about 3 x cm 2 molec -1, resulting in a detection limit for the IO slant column of approximately 2 x molec cm -2. With an AMF of about 16 for elevation angles of 2 and 90deg for measurement and reference respectively, the detection limit is only just below the observed VCD values after mid September of 1.5 x molec cm -2.

MAX-DOAS at Halley - tropospheric BrO and IO UV-visible sensors at BAS sites

MAX-DOAS at Halley - tropospheric BrO and IO UV-visible sensors at BAS sites Atkinson, H.M., R-J. Huang, R. Chance, H.K. Roscoe, C. Hughes, B. Davison, A. Schönhardt, A. S. Mahajan, A. Saiz-Lopez, P.S. Liss, “Iodine Emissions from the sea ice of the Weddell Sea”, submitted to Atm. Phys. Chem., ACPD 12, 11595–11639 (2012).

MAX-DOAS at Halley - tropospheric BrO and IO UV-visible sensors at BAS sites

MAX-DOAS at Halley - tropospheric BrO and IO Avantes spectrometer for BrO & IO: Jan 2012 to present UV-visible sensors at BAS sites

MAX-DOAS at Halley - tropospheric BrO and IO Avantes spectrometer for BrO & IO: Jan 2012 to present UV-visible sensors at BAS sites

SAOZ spare to Halley (76S) BAS funding cuts now and further cuts expected are such that we are planning now for when we cannot man the Dobson at Halley over winter. A SAOZ will measure ozone almost as well as the Dobson - except in summer (SZA too small at midnight at 76S) - except in winter (nothing to replace lunar Dobson) - needs AMF research to finish the work of Sarkissian (for 3 DU accuracy in Antarctic spring) A spare will go his December, run in parallel with the Dobson UV-visible sensors at BAS sites

1 30 SAOZ at Rothera (67S): · stratospheric O 3 and NO 2 since O 3 used to determine of ozone hole is recovering (Kuttippurath et al) - NO 2 used to infer trend in Brewer Dobson circulation (Cook & Roscoe) · 1-year overlap with replacement instrument in % rms difference in O 3, 5% max - 10% difference in NO 2, needs more investigation · analysis update should start in 2012 MAX-DOAS at Halley (76S): · tropospheric BrO and IO in 2007 (Halley), 2009 (Weddell), 2010 (Rothera), 2011 (Dome C), 2012 to present (Halley) - paper on BrO in 2007 about to be submitted to AMT (Roscoe et al) - paper including IO in 2009 submitted to ACP (Atkinson et al) · spectrometer replaced by Avantes (indoors in fridge) in good test results in Cambridge before leaving - but frequent software crashes at Halley despite separate USBs Spare SAOZ to Halley (76S). UV-visible sensors at BAS sites