The largest

INSTRUMENT DESCRIPTION MEASUREMENT SETTINGS

PEARL-GBS & UT-GBS PEARL Ground-Based Spectrometer (GBS) and University of Toronto GBS: Two nearly-identical UV-visible triplegrating spectrometers

• Ozone: 450-540 nm• NO2-vis: 425-450 nm• NO2-UV: 340-380nm• OClO: 340-380nm

SAOZ Système d’Analyze par Observations Zénitales: UV-visible spectrometer

• Ozone: 450-550 nm• NO2: (410-427 nm; 433-530 nm)*

2. Instrumentation and data analysis1. Introduction

The Arctic experienced a record ozone loss in Spring 2011. We present an investigation of this event in the context of eleven years of measurements taken at the Polar Environment Atmospheric Research Laboratory (PEARL) by three UV-visible spectrometers from 1999-2011. OClO is clearly enhanced in 2011, indicating chlorine activation above PEARL. While OClO is elevated, both ozone and NO2 measurements are lower than in any other year in the eleven-year record, suggesting ozone depletion and detrification. These measurements are evaluated in the context of the location of the polar vortex and other dynamical parameters.

3. Sampling

4. Dataset

Ozone, NO2, and OClO measured above PEARL during record ozone depletion in 2011

1C. Adams, 1K. Strong, 1X. Zhao, 1A. Fraser, 1J. Mendonca, 2F. Goutail, 2A. Pazmino, 3C.A. McLinden, 4,5G. Manney, 4W. Daffer1. Department of Physics, University of Toronto, Toronto, Canada; 2. LATMOS/CNRS, Verrieres le Buisson, France;

3. Environment Canada, Downsview, Canada; 4. Jet Propulsion Laboratory, California Institute of Technology; 5. New Mexico Institute of Mining and Technology, Socorro, New Mexico, USA

6. ReferencesFraser, A., C. Adams, J. R. Drummond, F. Goutail, G. Manney, and K. Strong (2009), The Polar Environment Atmospheric Research Laboratory UV-visible Ground-Based Spectrometer: First measurements of O3, NO2, BrO, and OClO columns, J. Quant. Spectrosc. Radiat. Transfer, 110, 986-1004, doi:10.1016/j.jqsrt.2009.02.034.

Hendrick, F., J.-P. Pommereau, F. Goutail, R. D. Evans, D. Ionov, A. Pazmino, E. Kyro, G. Held, P. Eriksen, V. Dorokhov, M. Gil, and M. V. Roozendael (2011), NDACC/SAOZ UV-visible total ozone measurements: improved retrieval and comparison with correlative satellite and ground-based observations, Atmospheric Chemistry and Physics, 11, 5975-5995, doi:10.5194/acp-11-5975-2011.

Manney, G. L., W. H. Daffer, J. M. Zawodny, P. F. Bernath, K. W. Hoppel, K. A. Walker, B. W. Knosp, C. Boone, E. E. Remsberg, M. L. Santee, V. L. Harvey, S. Pawson, D. R. Jackson, L. Deaver, C. T. McElroy, C. A. McLinden, J. R. Drummond, H. C. Pumphrey, A. Lambert, M. J. Schwartz, L. Froidevaux, S. McLeod, L. L. Takacs, M. J. Suarez, C. R. Trepte, D. C. Cuddy, N. J. Livesey, R. S. Harwood, and J. W. Waters (2007), Solar occultation satellite data and derived meteorological products: Sampling issues and comparisons with Aura Microwave Limb Sounder, J. Geophys. Res.-Atmos., 112.

Newman, P. A., and W. J. Randel (1988), Coherent Ozone-Dynamical Changes During The Southern-Hemisphere Spring, 1979-1986, J. Geophys. Res.-Atmos., 93, 12585-12606.

Pommereau, J. P., and F. Goutail (1988), O3 and NO2 ground-based measurements by visible spectrometry during Arctic winter and spring 1988, Geophys. Res. Lett., 15, 891-894.

Solomon, S., A. L. Schmeltekopf, and R. W. Sanders (1987), On the interpretation of zenith sky absorption-measurements, J. Geophys. Res.-Atmos., 92, 8311-8319.

7. AcknowledgmentsThe measurements at Eureka were made at the Polar Environment Atmospheric Research Laboratory (PEARL) by the Canadian Network for the Detection of Atmospheric Change (CANDAC), led by James R. Drummond, and in part by the Canadian Arctic ACE Validation Campaigns, led by Kaley A. Walker. They were supported by the Atlantic Innovation Fund/Nova Scotia Research Innovation Trust, Canada Foundation for Innovation, Canadian Foundation for Climate and Atmospheric Sciences, Canadian Space Agency, Environment Canada, Government of Canada International Polar Year funding, Natural Sciences and Engineering Research Council (NSERC), Northern Scientific Training Program, Ontario Innovation Trust, Polar Continental Shelf Program, and Ontario Research Fund. The authors wish to thank PEARL site manager Pierre F. Fogal, the CANDAC operators, and the staff at Environment Canada's Eureka weather station for their contributions to data acquisition, and logistical and on-site support.

Thank you to E. Farahani and M. Bassford for collecting the 1999-2003 GBS data.

Thank you to C. Fayt and M. Van Roozendael at IASB-BIRA for QDOAS software.

Thank you to NSERC Collaborative Research And Training Experience program for summer school funding.

Figure 1. March 18, 2011 ozone deviates from the 1978-1988 level by -40% above PEARL. Figure produced by Environment Canada Ozone Mapping Program with data from World Ozone Ultraviolet Radiation Data Centre and the Total Ozone Mapping Spectrometer.http://exp-studies.tor.ec.gc.ca/e/ozone/Curr_allmap.htm

Figure 3: Zenith-sky viewing spectrometers sample an air-mass along the path that sun follows to the instrument. Figure adapted from Solomon et al. [1987].

Table 1. Instrumentation and measurement settings for the three UV-visible spectrometers. Ozone columns were retrieved using cross-sections and air-mass-factors recommended by the Network for the Detection of Atmospheric Composition Change (NDACC) [Hendrick et al., 2010].

* SAOZ NO2 data were not used in this study because the SAOZ and GBS data were analyzed with different air-mass factors.

Figure 4: Location at which the ozone maximum (θ = 490 K) is sampled by the zenith-sky spectrometers at PEARL for solar zenith angle (SZA) 88° on various Julian days. As the sun sets further to the North, the sampling location shifts Northward.

Stratospheric parameters including temperature and location within the polar vortex [Manney et al., 2007] were calculated along the line-of-sight of the spectrometers.

PEARL is located at Eureka, Canada (80 N, 86 W) and operated by the Canadian Network for the Detection of Atmospheric Change (CANDAC).

www.ldeo.columbia.edu

Figure 2. Schematic of the polar vortex. Chemical ozone depletion can occur within the vortex during spring.

Inside the vortex

Outside the vortex

1 – 21 March 2011: Inside the polar vortex• Stratospheric temperatures below the threshold for polar stratospheric cloud formation • Elevated OClO indicates chlorine activation• Ozone and NO2 lowest in dataset, suggesting ozone depletion and denitrification

a) Ozone

b) NO2

c) OClO

Figure 5: (a) Ozone total columns measured by the UT-GBS, PEARL-GBS, and SAOZ. (b) NO2 total columns measured by the UT-GBS and PEARL-GBS in the visible and the UV spectral regions. (c) OClO differential slant column densities at SZA 90° measured by the UT-GBS and PEARL-GBS. (d) Stratospheric temperature and (e) sPV at θ = 490K calculated from the MetO and GEOS5 reanalyses.

Polar stratospheric clouds

22 March – 2 April 2011: On vortex edge• Stratospheric temperatures rise • OClO decreases• NO2 and ozone increase, but decrease sharply when re-entering vortex

2 – 15 April 2011: Exit vortex for last time• Stratospheric temperature rises to maximum in dataset • NO2 reaches maximum in dataset• Ozone stabilizes

d) Temperature near ozone maximum

e) sPV near ozone maximum

Figure 6: Linear regression of vortex (a) ozone and (b) NO2 versus stratospheric temperature at θ = 490 K for measurements 1-26 March. Values from 2011 are shown in black.

a)

b)

5. Analysis

Scaled potential vorticity (sPV): diagnostic used to determine vortex edge

Figure 7: Histogram of vortex ozone columns measured 1-26 March by the UT-GBS, PEARL-GBS and SAOZ. For ozone, the GBS and SAOZ datasets were combined as they differ on average by only 2.5%.

In 2011, ozone inside the vortex is 31±13% lower in than in other years.

Using sPV, ozone and NO2 data within the vortex in the lower stratosphere were selected for 1-26 March. Ozone and NO2 are correlated with stratospheric temperature as expected [e.g. Newman and Randel, 1988; Pommereau and Goutail, 1988]. The correlation between NO2 and stratospheric temperature is likely reduced because NO2 also increases with hours of sunlight throughout the spring.

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