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Notes: Summary The total ozone decline during the past twenty years, especially strong during the winter-spring season poleward from 50° N, is well established with known average trends of 5–7% per decade. This study presents a number of additional characteristics such as ozone-mass deficiency (O3MD) from the pre- 1976 base average, and areal extent with negative deviations greater than∼2 and∼3δ. Gridded satellite data combined with ground-based total ozone maps, permit calculations of daily and regional ozone deficiencies from the anthropogenically undisturbed average ozone levels of the 1960s and early 1970s. Then the quantity of the O3MD and the changes in surface area, with deficiencies larger than-10 and-15% are integrated for the 1 January to 15 April period for each of the last 20 years, and compared. In addition, the polar vortex extent during the last 10 years is determined using the PV at 475°K. The quantity of the O3MD within the sunlit part of the vortex is shown to contribute from∼15 to 35% of the overall ozone deficiency within the-10% contours over the area 35–90°N. The ozone deficiency, integrated for the first 105 days of each year, has increased dramatically from ∼2,800Mt in the early 1980s to∼7,800Mt in the 1990s, exceeded 12,000Mt in the winter-springs of 1993 and 1995. The latter quantity is comparable with the average O3MD over the same Southern latitudes in the last ten austral springs. During the 1990s over the 35–90° latitudes the average ozone deficiency in the Southern hemisphere belt is less than over the Northern hemisphere belt by∼40%. It is known that the main ozone decline is observed in the lower stratosphere and the ozone loss over the Arctic is very sensitive to decreasing stratospheric temperatures; negative 50hPa monthly anomalies greater than 4°C have occurred during 7 of the springs in the last decade, thus possibly facilitating doubling the area with negative ozone deviations greater than-10% in the 1990s to∼5,000.106km2 and nearly tripling the O3MD as stated above. The changes in total eddy heat fluxes as a proxy indicator of the long wave perturbations are positively correlated with the ozone deficiency in the 45–75°N. The strong anticorrelation between the ozone deficiency in the region〉55° N. versus the 35–50° N belt is discussed in relation to possible transport of air masses with low ozone from the sub-tropics, which in some years are the dominant reason for the observed ozone deficiency.

Notes: Abstract The chemically induced ozone loss inside the Arctic vortex during the winter 1994/95 has been quantified by coordinated launches of over 1000 ozonesondes from 35 stations within the Match 94/95 campaign. Trajectory calculations, which allow diabatic heating or cooling, were used to trigger the balloon launches so that the ozone concentrations in a large number of air parcels are each measured twice a few days apart. The difference in ozone concentration is calculated for each pair and is interpreted as a change caused by chemistry. The data analysis has been carried out for January to March between 370 K and 600 K potential temperature. Ozone loss along these trajectories occurred exclusively during sunlit periods, and the periods of ozone loss coincided with, but slightly lagged, periods where stratospheric temperatures were low enough for polar stratospheric clouds to exist. Two clearly separated periods of ozone loss show up. Ozone loss rates first peaked in late January with a maximum value of 53 ppbv per day (1.6 % per day) at 475 K and faster losses higher up. Then, in mid-March ozone loss rates at 475 K reached 34 ppbv per day (1.3 % per day), faster losses were observed lower down and no ozone loss was found above 480 K during that period. The ozone loss in hypothetical air parcels with average diabetic descent rates has been integrated to give an accumulated loss through the winter. The most severe depletion of 2.0 ppmv (60 %) took place in air that was at 515 K on 1 January and at 450 K on 20 March. Vertical integration over the levels from 370 K to 600 K gives a column loss rate, which reached a maximum value of 2.7 Dobson Units per day in mid-March. The accumulated column loss between 1 January and 31 March was found to be 127 DU (∼36 %).