Increased UV radiation due to polar ozone chemical depletion and vortex occurrences at Southern Sub-polar Latitudes in the period [1997–2005] A. F. Pazmiño1,2, S. Godin-Beekmann1, E. A. Luccini3,4, R. D. Piacentini3,5, E. J. Quel6, and A. Hauchecorne2 1UPMC Univ. Paris 06, UMR 7620, Service d'Aéronomie, F-75005, Paris, France; CNRS, UMR 7620, Service d'Aéronomie, F-75005, Paris, France 2Université Versailles St-Quentin, CNRS, UPMC, Service d'Aéronomie, Route Forestière de Verrières, 91370 Verrières-le-Buisson, France 3Instituto de Física Rosario (CONICET – Universidad Nacional de Rosario), Rosario, Argentina 4Facultad de Química e Ingeniería "Fray Rogelio Bacon", Universidad Católica Argentina, Rosario, Argentina 5Facultad de Ciencias Exactas, Ingeniería y Agrimensura, Universidad Nacional de Rosario, Rosario, Argentina 6CEILAP (CITEFA-CONICET), Villa Martelli, Argentina
Abstract. The variability of total ozone and UV radiation from Total Ozone Mapping
Spectrometer (TOMS) measurements is analyzed as a function of polar vortex
occurrences over the southern subpolar regions during the 1997–2005 period.
The analysis of vortex occurrences showed high interannual variability in the
40° S–60° S latitude band with a longitudinal asymmetry
showing the largest frequencies over the 90° W–90° E region.
The impact of vortex occurrences on UV radiation and ozone in clear sky
conditions was determined from the comparison between the measurements inside
the vortex and a climatology obtained from data outside the vortex over the
studied period. Clear sky conditions were determined from TOMS reflectivity
data. For measurements outside the vortex, clear sky conditions were selected
for reflectivity values lower than 7.5%, while for measurements inside the
vortex, a relaxed threshold was determined from statistically similar UV
values as a function of reflectivity. UV changes and ozone differences from
the climatology were analyzed in the 40° S–50° S and
50° S–60° S latitude bands during the spring period
(September to November). The largest UV increases and ozone decreases,
reaching ~200% and ~65%, respectively, were found in the
50° S–60° S latitude band in September and October. The
heterogeneous ozone loss during vortex occurrences was estimated using a
chemical transport model. The largest impact of vortex occurrences was found
in October with mean UV increase, total ozone decrease and accumulated ozone
loss in the 350–650 K range of, respectively, 47%, 30% and 57%. The
region close to South America is the most affected by the Antarctic ozone
depletion due to the combined effect of large number of vortex occurrences,
lower cloud cover and large ozone decrease. This region would be the most
vulnerable in case of cloud cover decrease, due to more frequent occurrence
of ozone poor air masses during austral spring.
Citation: Pazmiño, A. F., Godin-Beekmann, S., Luccini, E. A., Piacentini, R. D., Quel, E. J., and Hauchecorne, A.: Increased UV radiation due to polar ozone chemical depletion and vortex occurrences at Southern Sub-polar Latitudes in the period [1997–2005], Atmos. Chem. Phys., 8, 5339-5352, doi:10.5194/acp-8-5339-2008, 2008.