REMEMBRANCE

JOHN SWALLOW, ER.S. 1923-1994

JOHN SWALLOWdied suddenly following tronics. The war years, when he served features in the deep sea floor provided a heart attack at his home in Cornwall, with the Navy maintaining radar systems, the reference. Each fix took several hours England last December, 1994 aged 71. were a very practical interruption of his instead of the few seconds we expect He was as busy as at any time in thinking university career. They were also his first these days anywhere in the world. about and illuminating the character of introduction to the Indian at the In the mid 1950"s Henry Stommel's the large-scale circulation. I want to write Trincomalee naval base in Ceylon (Sri ideas about deep circulation were ripe for about what made him such a fine ocean- Lanka). testing. These led to a life-long collabora- ographer, colleague, and friend of many He himself remarked that his geophys- tion between Henry and John. A joint of us. For the record, I've included a ical acquaintance with the effects of com- cruise of Atlantis and Discovery 11 chronology of the bare bones of his ca- pressibility led to the critical idea that it demonstrated a high-velocity deep south- reer and a complete list of his publica- was practical to build an instrument less ward flow under the , consis- tions. compressible than seawater that could be tent with the idea of an undercurrent. In 1954, at the National Institute of stabilized at depth and that could be This was followed by the 15-month-long , Wormley in the UK, tracked over many weeks. This was to observations in the Aries in 1959-60, some of us were trying to find a way to revolutionize our understanding of deep originally planned to examine Stommel's measure deep (slow) ocean currents. We circulation, as the only instrument capa- hypothesis of deep poleward flow in the had come up with what one could call a ble of measuring extremely small cur- ocean interior. This was an intensive pe- prehistoric version of the Pegasus system rents over periods of time. Even measure- riod of sea-going, with the Bermuda Bio- developed at the Woods Hole Oceano- ments with the new long-term deep logical Station as home port. John's wife graphic Institution in the 70"s. It didn't current meters could not reach the thresh- Mary, librarian of NIO and later co-editor succeed. The seals used on the equip- old measurement of "'Swallow" floats. of Deep Sea Research, whom he had ment, based on shallow-water technol- The descendants of these early pieces of married the year before, maintained the ogy, were inadequate for deep water. It aluminum tube, the ALACE and RAFOS and radio contact between the ship and the was difficult to make a taut mooring (dan MARVOR floats, have built on these early Bermuda Biological Station. buoys on thin piano wire were standard) beginnings and made possible the precise The deep water proved rather ener- and the broad spectrum down to tidal t're- global measurements of the deep water getic, moving at 10-20 cm/sec, and was quencies cast doubt on the profiling flow that are happening today, certainly not amenable to short-term ob- method that we had adopted. Putting the technique to work effec- servation of the mean flow. This led to a However, out of disappointment came tively demonstrated another quality use- significant reorientation of the plans and success. John Swallow had come to the ful in experimental science, If a tech- redesign of the floats. They had been de- lab with Maurice Hill of the Department nique works, then first and foremost use signed for use over many months with of Geodesy & Geophysics at Cambridge it--make improvements when possible, clocks controlling their duty cycle to pre- to discuss the use of geophysics technol- but use it. The eastern Atlantic was not serve battery power. Both the intellectual ogy (sonar receivers and short-term deep- the ideal place to establish the new tech- challenge, confronted with the unex- sea mooring techniques) to our experi- nique, radio-navigation was non-existent pected, and the technical challenge far ment, Having nearly finished his Ph.D., offshore, and as it turned out the ~'mean" from the lab, were met. He was quickly and with impeccable timing by Dr. Dea- currents were very small (1-2 cm/sec). back at sea with a set of free-running con, the Director of NIO, he accepted the So, with range fixing of the floats possi- floats, double in number through saved offer of a job at NIO to work on deep ble to a fraction of a km, the challenge buoyancy, which in retrospect may well current measurements. Unusually for a was to convert that to an absolute refer- have been more robust than the initial de- graduate student, he had had several ence frame. Trivial these days with the sign. The 15 months of observation that years at sea in HMS Challenger on its Global Positioning System, but not then. followed established the significance of round-the-world surveying cruise. John It was traditional in the Discovery Inves- mesoscale eddies in the ocean and over was collecting seismic profiling data on tigations and post-war in NIO to maintain the next decades shifted the direction of sediment thickness for his Ph.D. This echosounding watches in deep water and theoretical and observational studies of background of seismic observation to extend the accuracy of the echo deep-ocean dynamics. brought a wealth of practical knowledge, sounder, so there was the basis of a good This Aries experience illuminated oth- some of it not widespread in physical map of the eastern Atlantic with the ers of John's characteristics. There were oceanography, knowledge about moor- abyssal plain and its bumps mapped to occasions when the Aries was short of a ings and navigation and O-rings and elec- the nearest metre or two. These small cook in the 6-man crew, or someone to

OCEANOGRAPHY'VoI.10, No. 1"1997 27 fix the engines. On these occasions, be- cult to observe, particularly in winter. meetings planning for specific scientific tween stations, we rediscovered his inter- There were very few observations to sup- programs, most recently for the current est in food and cooking, already known port the process. The thought that the Indian Ocean phase of the World Ocean to his shipmates on HMS Challenger. NW Mediterranean off the Rhone fan Circulation Experiment and the Joint This interest kept us on schedule and might be a mini-laboratory for the pro- Global Ocean Flux Study. gave us good food. cess proved fruitful. A combination of Retirement in 1983 was in name only The 63-64 cruise of the new Discov- strong evaporation and winter cooling in terms of work. Seagoing continued and ery to the Indian Ocean in the Interna- from the Mistral led to the notion of a publications if anything increased. Very tional Indian Ocean Expedition marked pre-conditioning phase involving rapid recently he was contemplating the pur- the early beginnings of the main work of cooling and evaporation of the surface chase of a computer but his contributions the last 30 years of his career before and followed by deep overturning in narrow to the collaborations were perhaps even after retirement. The monsoon regime chimneys to depths of 2000m and greater enhanced by the lack of distraction that gave rise to insights into western bound- in a day or two. This was a good para- the purchase might have brought to his ary and equatorial currents under a domi- digm for the open ocean. The sub-zero working day. nant seasonal forcing. These led to strong temperatures and gales also gave all on He and Mary made their home in theoretical interest in the detailed descrip- the Charcot, Discoveo'. and Athmtis H an Cornwall, looking out on Dartmoor tion of the processes. Practically, there alternative view of the climate of the (when the mist wasn't down), and close were real problems in making good hy- Riviera. It was still preferable to high lat- to that of their much loved Lucy, Mary's drographic profiles in a current of 5 knots itudes in winter. The planning meeting daughter, who sadly died a year before shearing to near zero at 100m. Did one for that multiship programme took place John. It was a place for colleagues to let the ship drift with big wire angles to on just one day at the Institute of Ocean- visit and to work in peace, and in which get a good localized vertical profile in the ographic Sciences (formerly the NIO), to enjoy great hospitality. deep water? Spice and excitement were Wormley. added to the occasion by having our biol- A decade on from the Aries work James Crease ogists aft working their nets at the same there was the opportunity to take part in April 1995 time as the hydro work forr'd. Leadership the Mid Ocean Dynamics Experiment of high quality is called for in such multi- (MODE) in the west Atlantic. This ex- Career disciplinary cruises. periment was specifically designed to St Johns College Cambridge 194143 The return home through the Red Sea study the mesoscale in a two-degree box Admiralty Signals and Radar Establish- was the occasion for one of those occa- over several months in 1973. It involved ment, Haslemere & Trincomalee Royal sions of special excitement that are partic- a mix of many US labs, of theoreticians Naval Base, Ceylon (Sri Lanka) 1943-47 ularly rewarding through their infre- and experimentalists, and of new and Research Student, Dept. of Geodesy and quency. The presence of anomalous water standard techniques that provided a Geophysics, Cambridge 1947-54 of higher temperature at the bottom of the wealth of data. John brought the Discov- Ph.D. Cambridge 1955 Red Sea had been known but the high ery along and used his short range floats Scientific Officer-Deputy Chief Scientific temperature brine of the "Discovery to make a more intensive "mini-mode" Officer at NIO/IOS, UK 1954-1983 Deep" in the Red Sea median valley was study of a small part of the area. The Rossby Fellow, Woods Hole Oceano- quite unsuspected. It was to provide a nice larger area was covered by moored cur- graphic Institution 1973-74 field demonstration of one of the modes of rent meter arrays and the longer-range double diffusion, which was being studied sofar floats. Honours and Awards actively at WHOI and Cambridge. Following MODE John's interests 1960 Albatross Award of the American Back in the North Atlantic, work with turned more to the Indian Ocean and he Miscellaneous Society (an Albatross Val Worthington in the Labrador Sea in embarked on a 20-year-long collaboration acknowledges a Swallow!) winter led on a few years later to the idea with Michale Fieux, Fritz Schott, Bob 1962 Bigelow Medal, Woods Hole of studying, with WHOI and with the Molinari, John Bruce, Bruce Warren, and Oceanographic Institution group at the Museum National d'Histoire others which ranged widely over the In- 1965 Murchison Grant, Royal Geographi- Naturelle, the onset of deep convection in dian Ocean. The Somali current, the cal Society the NW Mediterranean. The MEDOC equatorial regime and the fine structure of 1968 Fellow of Royal Society of (MEDiterranee OCcidentale, or maybe, the currents there in the vertical, and 1978 Sverdrup Gold medal of the Ameri- MEDiterranean OCeanography) experi- most recently the Indonesian through- can Meteorological Society ment proved to be a good vintage. The flow were illuminated in a series of 38 1984 Prince Albert I of Monaco Medal formation regions of deep water in the papers and reports. 1994 Stommel Medal, Woods Hole open ocean were rather remote and diffi- He was always ready to spend time on Oceanographic Institution

28 OCEANOGRAPHY*VoI. 10, No. 1-1997