Variability in sun photometer derived summertime total column ozone over the Indian station Maitri in the Antarctic region

Extensive observations of total column ozone (TCO) made over the Antarctic region at the Indian station 'Maitri' (70.76oS, 11.74oE) during two summer periods of 2004-2005 and 2006-2007 using a ground-based optical remote sensing instrument (ozonometer) have been examined to study the short-term variations. Mean TCO during 2004-05 summer was 288.7 DU with a variability of 8% and the corresponding values during 2006-2007 summer were 280.4 DU and 11%. Both ozonometer and Dobson spectrophotometer measurements at this Antarctic station during January 2005 showed a short-term decrease in TCO by about 70 DU before regaining original value. Simultaneous changes in precipitable water and surface temperature points to a possible interplay of chemistry and meteorological conditions. Occurrence of an intense solar proton event in January 2005 also suggests the possible role of precipitating charged particles in causing short-lived ozone decrease through production of OH radical.