where is the density of the ozone and the concentration. Total ozone is expressed in Dobson units (DU). See Salby (1992).
Atmospheric nuclear weapons testing in the 1950s and 1960s produced tritium in quantities that dwarfed the natural inventory which, given the subsequent cessation of such testing, offered a unique opportunity to study the long-term transport through the ocean of a large spike of an important and readily identified tracer. About 500 kg of tritium was produced by the weapons testing programs, boosting the concentration in precipitation to as high as 10,000 TU in places, with surface seawater concentrations reaching 20-30 TU in the northern hemisphere. The latitudinal distribution of weapons tritium delivery to the ocean is characterized by mid-latitude maxima (near 45-50 ) with about a five-fold asymmetry between northern and southern hemisphere. The time history of surface delivery is a spike for the northern hemisphere and more extended for the southern hemisphere.
The usefulness of tritium as a tracer is due to its time history not monotonically increasing (i.e. the weapons source is no more) which gives independent time information, the strong hemispheric asymmetry in its delivery which is valuable in the study of cross-equatorial flow and, finally, its nature as an ideal fluid tracer since, being part of the water molecule, it is unaffected by biological and chemical processes. The long-term evolution of its large-scale distribution will provide much useful information about ocean circulation processes. See Sarmiento (1988) and Broecker and Peng (1982).
Tsunamis are primarily created by vertical movements of the sea floor caused by tectonic activity. This causes rapid vertical movements in the sea surface over a large area which leads to the formation of a train of very long period waves, with periods exceeding one hour not unusual. Secondary mechanisms for tsunami formation are landslides and volanic activity, with the effects of the resultant waves more localized than those of the tectonic variety which may travel across ocean basins. See Camfield (1990).