Impact of Antarctic polar vortex occurrences on total ozone and UVB radiation at southern Argentinean and Antarctic stations during 1997–2003 period

Andrea Pazmino (1, 2) , Sophie Godin-Beekmann (2) , Maximo Ginzburg (3) , Slimane Bekki (2) , Alain Hauchecorne (2) , Ruben D. Piacentini (4, 5) , Eduardo J. Quel (1)

1 CEILAP - Centro de Investigaciones en Láseres y Aplicaciones [Buenos Aires]
2 SA - Service d'aéronomie
3 Servicio Meteorológico Nacional [Buenos Aires]
4 FCEIA - Facultad de Ciencias Exactas, Ingenieria y Agrimensura [Rosario]
5 IFIR - Instituto de Física de Rosario [Santa Fe]

The evolution of total ozone and surface UV radiation over some stations in the southern region of South America and in Antarctica in relationship with polar vortex occurrences is analyzed using Total Ozone Mapping Spectrometer total ozone measurements and local surface UV data for the 1997–2003 period. The data are classified as a function of the position of the stations with respect to the polar vortex using equivalent latitude at 550 K isentropic level. The study of vortex occurrences showed that Ushuaia station (54.9°S) was located Å`40% of the cases in the edge of the vortex and 5% inside the vortex core during the winter-spring period. Concerning the Marambio (62.2°S) and Dumont d'Urville (66.4°S) stations, located on the shore of the Antarctic continent, the analysis shows a zonal asymmetry with respect to the center of the vortex. Marambio is located around 60% of the time inside the vortex, while Dumont d'Urville is predominantly at the edge of or outside the vortex. The evolution of the equivalent latitude of the stations in the anomalous 2002 winter presents a different behavior with respect to other years in the 1997–2003 period. The persistence of the vortex core above the stations is in average 1.8 days over Ushuaia and 7.1 days over Marambio in October during the 1997–2003 period with corresponding mean total ozone columns of 208.2 and 181.4 Dobson units, respectively. When the stations are inside the vortex, the total ozone columns are generally larger at Ushuaia than at Marambio in October during the 1997–2003 period. Finally, the impact of ozone-depleted air mass occurrences on ultraviolet radiation is evaluated by relating total ozone and UV erythemal dose measured at the stations. Twofold or threefold UV dose increases were reached in the 55°–65° southern latitude region during vortex overpasses, reaching maximum UV dose around 5 kJ/m2. The average increase of UV dose could be computed at the stations considered in the study when the measurement sampling and the number of vortex occurrences was sufficient. An average increase of 67.6% of the erythemal UV dose was found in October at Ushuaia over the years 1997, 1998, and 2000. This value is strongly weighted by vortex occurrences over the station in 2000. At Marambio an average UV increase of 47.4% was found over the years 1999 and 2000. Midlatitude stations like Comodoro Rivadavia (45.8°S) are generally little affected by vortex intrusions. Nevertheless, the maximum UV dose can increase by more than 50% when the vortex passes over the station.

Domaines: Physique Atmosphérique et Océanique [physics.ao-ph]

Andrea Pazmino, Sophie Godin-Beekmann, Maximo Ginzburg, Slimane Bekki, Alain Hauchecorne, et al.. Impact of Antarctic polar vortex occurrences on total ozone and UVB radiation at southern Argentinean and Antarctic stations during 1997–2003 period. Journal of Geophysical Research: Atmospheres, 2005, 110 (D3), pp.D03103. ⟨10.1029/2004JD005304⟩. ⟨hal-00078179⟩