World Ocean Circulation Experiment
185
The technologies that I was aware of were several. CTDs were gradually becoming easier to use and more widespread. Autoanalyzers were available for nutrient
measurements. Titration salinities had been replaced by conductivity methods. Transient tracers, tritium, helium-3, and chlorofluorocarbons were measurable. Bottom
pressure gauges had become stable enough to yield months-long records. The neutrally buoyant float methods were rapidly advancing beyond the SOFAR method
used in MODE-1 to RAFOS (Rossby et al., 1986) and what eventually became the
ALACE floats (Davis et al., 1992). In the summer of 1977, Walter Munk and I (Munk
and Wunsch, 1979) had stumbled on the idea of ocean acoustic tomography, which
promised to provide large area integrals over the ocean. Perhaps most important, however, was the prospect of certain satellite measurements of the ocean, in particular
scatterometry for winds, altimetry for circulation, and gravity for determining the
absolute circulation.
Altimetry and tomography were my own particular foci, and as W. Munk describes the evolution of the acoustical capability elsewhere in this volume, perhaps I
can be permitted some words about altimetry.
3
I cannot do justice here even to the history of altimetry, much less all of the other
technologies that were emerging at that time. I would argue, however, that altimetry
has played a unique role as, to this day, it remains the only true global ocean measuring
system (scatterometers and other devices measure parts of the forcing, not the ocean
itself).
Altimetric Measurements
Like most physical oceanographers, I had no experience with remote sensing from
space, when in 1974 I had a telephone call from Dr. Peter Bender, a space geodesist
working for NOAA in Boulder. Peter explained that he was chairman of the Committee
on Earth Sciences of the Space Science Board of the National Research Council, and
that they were trying to write a report discussing, in part, what NASA should be doing
to better understand the ocean. My response, which was a flat refusal, clearly startled
Bender. I told him that NASA’s contribution to oceanography seemed all hype—based
upon a few not-very-accurate infrared measurements of sea surface temperature from
space. Sea surface temperature was of much more interest to meteorologists than to
oceanographers in any case, and I thought that NASA’s public relations machinery
was far outstripping the importance of its contribution. After a stunned silence on the
other end of the telephone line, Bender said that if things were really so bad it was
even more important that I should serve on the Committee, so that the Report would
reflect the reality. In a weak moment, I then agreed.
At that time, NASA’s oceanographic interests were focussed on the so-called
SEASAT-A spacecraft which was to fly circa 1977. It is hard now to credit an era in
3 In the end, tomography played only a small role in WOCE as the acoustic technology did not develop as
rapidly as hoped. It may now be on the verge of large-scale use.
185
The technologies that I was aware of were several. CTDs were gradually becoming easier to use and more widespread. Autoanalyzers were available for nutrient
measurements. Titration salinities had been replaced by conductivity methods. Transient tracers, tritium, helium-3, and chlorofluorocarbons were measurable. Bottom
pressure gauges had become stable enough to yield months-long records. The neutrally buoyant float methods were rapidly advancing beyond the SOFAR method
used in MODE-1 to RAFOS (Rossby et al., 1986) and what eventually became the
ALACE floats (Davis et al., 1992). In the summer of 1977, Walter Munk and I (Munk
and Wunsch, 1979) had stumbled on the idea of ocean acoustic tomography, which
promised to provide large area integrals over the ocean. Perhaps most important, however, was the prospect of certain satellite measurements of the ocean, in particular
scatterometry for winds, altimetry for circulation, and gravity for determining the
absolute circulation.
Altimetry and tomography were my own particular foci, and as W. Munk describes the evolution of the acoustical capability elsewhere in this volume, perhaps I
can be permitted some words about altimetry.
3
I cannot do justice here even to the history of altimetry, much less all of the other
technologies that were emerging at that time. I would argue, however, that altimetry
has played a unique role as, to this day, it remains the only true global ocean measuring
system (scatterometers and other devices measure parts of the forcing, not the ocean
itself).
Altimetric Measurements
Like most physical oceanographers, I had no experience with remote sensing from
space, when in 1974 I had a telephone call from Dr. Peter Bender, a space geodesist
working for NOAA in Boulder. Peter explained that he was chairman of the Committee
on Earth Sciences of the Space Science Board of the National Research Council, and
that they were trying to write a report discussing, in part, what NASA should be doing
to better understand the ocean. My response, which was a flat refusal, clearly startled
Bender. I told him that NASA’s contribution to oceanography seemed all hype—based
upon a few not-very-accurate infrared measurements of sea surface temperature from
space. Sea surface temperature was of much more interest to meteorologists than to
oceanographers in any case, and I thought that NASA’s public relations machinery
was far outstripping the importance of its contribution. After a stunned silence on the
other end of the telephone line, Bender said that if things were really so bad it was
even more important that I should serve on the Committee, so that the Report would
reflect the reality. In a weak moment, I then agreed.
At that time, NASA’s oceanographic interests were focussed on the so-called
SEASAT-A spacecraft which was to fly circa 1977. It is hard now to credit an era in
3 In the end, tomography played only a small role in WOCE as the acoustic technology did not develop as
rapidly as hoped. It may now be on the verge of large-scale use.