Researching Townsend Cromwell

From 1949 to 1953 he was Oceanographer at Pacific Oceanic Fishery Investigations, Honolulu, Oscar Elton Sette, then Director, and Cromwell initiated a far-sighted and intensive survey of the physical and biological characteristics of Pacific equatorial waters, which had been the subject of much speculation but little observation. For many months he participated in the field work from the fisheries research ship, and for more and harder months he carried out the analysis of the observations. As a result of this pioneering work, the knowledge of the physical and biological structure of the equatorial Pacific Ocean has been vastly advanced. These achievements are the more remarkable when one notes that comparable surveys of the equatorial Atlantic and Indian oceans are still lacking.

Cromwell confirmed the existence of upwelling at the equator, disproved the existence of upwelling at the northern edge of the Equatorial Countercurrent, and originated a reasonable model of wind-induced current transport in the equatorial zone During these studies he recognized the significance of the unexpected drift of long-line fishing gear at the equator, and in 1952 he led a Hugh M. Smith cruise using drogues in current measurements. Thus, he was responsible for the discovery of the Equatorial Undercurrent the fourth member of the equatorial current system (the North Equatorial Current, Equatorial Countercurrent, and South Equatorial Current having been known for a century).

The existence of the Equatorial Undercurrent has been amply confirmed, during measurements completed a few days before Cromwell’s death, by his colleagues J. A. Knauss and J. E. King. One result of four years in close collaboration with W. S. Wooster is a joint publication, in color, of a systematic analysis of data from the eastern tropical Pacific Ocean (Bull. Scripps Inst. Oceanogr., 1958). The subject that aroused Cromwell’s keenest interest is the structure and formation of oceanic discontinuities, both fronts and thermoclines (Tellus, 1956; Bull. inter-Amer. trop. Tuna Comm., in press). His work was characterized throughout by close collaboration with his associates, who became his devoted friends. His personal charm and modesty, together with his scientific interest, led a number of oceanographers to join his field of activity. These include E. D. Stroup, G. W. Groves, and R. B. Montgomery.