In 1887 Krümmel published the monumental Handbuch der Ozeanographie, which immediately attained status as the standard reference source for physical oceanographic information. The Handbuch contained a global chart of the ocean surface circulation that depicted all of the major currents in the proper locations. This chart also showed the monsoonal cycle in the northern Indian Ocean via an inset, a new cartographic technique that has since come into wide use. Extensive descriptions of surface circulation features were included, although theory was dealt with from a historical point of view as the field was still in its nascent stages in the latter part of the nineteenth century. He did discuss the work of William Ferrel and Henrik Mohn regarding the effects of the earth's rotation, although the results of some tank experiments led him to believe that the deflecting force would be relatively small in most cases. See Peterson et al. (1996).
Its source to the ocean is well known due to extensive measurements of the atmospheric concentrations over time. This, along with its chemical inertness, are valuable properties for an ocean tracer to have. It enters the ocean by gas exchange, equilibrating with surface water on a time scale of about one month. This equilibrium concentration can be calculated from krypton solubility, a function of temperature and salinity, and from the atmospheric krypton concentration. This procedure won't apply in regions of rapid vertical mixing since the surface water doesn't have time to come into equilibrium with the atmosphere, but direct measurements in those regions can alleviate this problem. A measurement requires a water volume of 250 l, and the dynamic range of the measurement of krypton-85 (i.e. the ratio of the surface water concentration to the minimum detectable amount) is around 100. Measurement precision is +/- 4% for surface samples and +/- 25% for samples with concentrations 3% that of surface water.
Kr-85 is used as a tracer for study processes that occur on a decadal time scale, e.g. thermocline ventilation, mixing, circulation, and deep water mass formation, due to it being introduced to the atmosphere only in the last 35-40 years. See Sarmiento (1988) and Broecker and Peng (1982).