The penetration of the bomb tritium and radiocarbon transients into the Pacific Ocean

We now have three snapshots of the penetration of bomb-transient tracers (tritium and radiocarbon) into the Pacific Ocean: from GEOSECS in the 1970s, WOCE in the 1990s, and CLIVAR in the early twenty-first century. As transient tracers, these properties provide valuable insights and useful constraints on ocean ventilation and circulation, and on their possible variation in time. We present some snapshots of their evolving distributions with time. While their ultimate value will be realized within the framework of more sophisticated and comprehensive models (along with additional observational constraints that include geostrophy, current meters, floats and other tracers), we attempt to outline some of the useful information that may be gleaned from such observations based on simple analysis. Moreover, we identify some features that are suggestive of fundamental changes in the nature of the global thermohaline overturning circulation.