The total hydrogen budget in the Arctic winter stratosphere during the European Arctic Stratospheric Ozone Experiment

Vertical profiles of H2O and CH4 were measured using in situ techniques in the Arctic winter stratosphere during the European Arctic Stratospheric Ozone Experiment (EASOE) 1991/1992 in the pressure range between 12 and 80 hPa. The measurements were grouped according to the meteorological situation, i.e., their position relative to the polar vortex. The mixing ratio of the quantity 2 . CH4 + H2O was determined in the altitude region between the hygropause and 30 km to be quasi constant at a mean mixing ratio of 6.91 +/- 0.41 ppmv. No significant difference of 2 . CH4 + H2O was observed inside and outside the vortex. From the correlation between CH4 and H2O Delta H2O/Delta CH4, i.e., the water vapor yield of the methane oxidation, was calculated to be -1.82 +/- 0.21. The globally averaged H2O mixing ratio of air entering the stratosphere was found to be 3.61 +/- 0.28 ppmv. The data are compared with studies on the total hydrogen budget over the past 20 years. Despite the variety of instrumental techniques used in these studies, an increase of total hydrogen is apparent over this period.