Molecular hydrogen in the atmosphere

The distribution of molecular hydrogen in the troposphere, the lower stratosphere, as well as ocean surface waters of the Atlantic Ocean region was studied. A rather constant mixing ratio of 0.548 ± 0.015 ppmv was found in the southern troposphere and in the lower stratosphere of the northern hemisphere. Statistically significant higher levels of 0.558 ± 0.019 ppmv and 0.585 ± 0.029 ppmv have been obtained in the northern hemisphere in the upper troposphere and in surface air respectively. The data do not indicate any change in the H2 mixing ratio in the lower stratosphere up to 4 km above the tropopause. Surface waters of the Atlantic Ocean appeared to be supersaturated by a factor of about 3. Vertical profiles showed distinct maxima between 500 and 1000 m depth. The discussion of sources and sinks leads to a tropospheric residence time of about 4 to 7 years.