Mean annual cycle of the air-sea oxygen flux: A global view

A global monthly-mean climatology of the air-sea oxygen flux is presented a nd discussed. The climatology is based on the ocean oxygen climatology of N ajjar and Keeling [1997] and wind speeds derived from a meteorological anal ysis center. Seasonal variations are characterized by outgassing of oxygen during spring and summer and ingassing of oxygen during fall and winter, a pattern consistent with thermal and biological forcing of the air-sea oxyge n flux. The annual mean flux pattern is characterized by ingassing at high latitudes and the tropics and outgassing in middle latitudes. The air-sea o xygen flux is shown to exhibit patterns that agree well with patterns seen in a marine primary productivity climatology, in model generated air-sea O- 2 fluxes, in estimates of remineralization in the shallow aphotic zone base d on seasonal oxygen variations, in observed seasonal nutrient-temperature relationships, and in independent estimates of meridional oxygen transport in the Atlantic ocean. We also find that extratropical mixed layer new prod uction during the spring-summer period, computed from biological seasonal n et outgassing of oxygen, is equivalent to the production of 4.5-5.6 Gt C, m uch lower than previous estimates based on atmospheric O-2/N-2 measurements .