El Ni ˜
no and Ocean Observations
83
EPOCS and NORPAX joined forces to coordinate the deployment of moored
buoy arrays spanning 152
◦ W (NORPAX) and 110
◦ W (EPOCS) in the equatorial
Pacific in 1979–80. Bob Knox, who was lead investigator at Scripps for the NORPAX
moorings, temporarily enlisted my help to prepare mooring hardware as the time approached for field work to begin. This brief “hands on” experience was later rewarded
with the satisfaction of having made a minor contribution to a major success story.
The NORPAX/EPOCS moorings, combined with tide gauge measurements from the
Galapagos Islands (91
◦ W), detected the eastward propagation of a pulse in zonal
currents and sea level along the equator over 60
◦ of longitude in April–May 1980
(Knox and Halpern, 1982). This pulse propagated at the phase speed expected for
a first baroclinic mode equatorial Kelvin wave and constituted the first compelling
evidence for the existence of a key building block in Wyrtki’s theory for El Ni˜ no.
3
DRIFTING THERMISTOR CHAINS, PART I
My Ph.D. dissertation in 1980 was on theories of equatorial ocean circulation, including the effects of mean flows like the Equatorial Undercurrent on equatorial Kelvin
waves. However, late in my graduate studies and as a postdoc at the National Center
for Atmospheric Research (NCAR), I became interested in observational analyses and
observing system development. Francis Bretherton and Eric Kraus entrained me in a
feasibility design study for the “CAGE” experiment, an international effort intended
to measure the heat balance of the North Atlantic from the top of the atmosphere to the
bottom of the ocean (Bretherton et al., 1984). The design study identified significant
challenges, especially for estimating atmospheric heat flux divergences, which would
make it difficult to compute the balance within specified error tolerances (Bretherton
et al., 1982). CAGE (not an acronym but intended to describe the volume over which
measurements would be made) was thus never carried out, though it did influence
later design of the World Ocean Circulation Experiment (WOCE).
As an offshoot of my involvement in CAGE, Eric Kraus introduced me to
Jose Gonella of the Museum of Natural History in Paris, principal investigator of a
drifting thermistor chain project as part of the Programme Fran¸ cais Oc´ ean et Climat
dans l’Atlantique Equatorial (FOCAL). FOCAL was a French complement to the
Seasonal Response of the Equatorial Atlantic (SEQUAL) program, a U.S. initiative
to study the seasonal cycle of the tropical Atlantic over a 2-year period from 1982 to
1984. Jose was interested in developing a deployment strategy for the FOCAL drifters,
and asked whether we could use the same techniques we developed for CAGE for this
purpose. It was our opinion that we could and I volunteered to work on the problem.
I subsequently spent March–April 1982 in Paris and Brest collaborating with French
3 An El Ni˜ no did not develop in 1980 because there was no prior large-scale accumulation of excess upper
ocean heat content along the equator, which is required in addition to the excitation of equatorial Kelvin
waves for El Ni˜ no onset (Wyrtki, 1985; Cane et al., 1986).
no and Ocean Observations
83
EPOCS and NORPAX joined forces to coordinate the deployment of moored
buoy arrays spanning 152
◦ W (NORPAX) and 110
◦ W (EPOCS) in the equatorial
Pacific in 1979–80. Bob Knox, who was lead investigator at Scripps for the NORPAX
moorings, temporarily enlisted my help to prepare mooring hardware as the time approached for field work to begin. This brief “hands on” experience was later rewarded
with the satisfaction of having made a minor contribution to a major success story.
The NORPAX/EPOCS moorings, combined with tide gauge measurements from the
Galapagos Islands (91
◦ W), detected the eastward propagation of a pulse in zonal
currents and sea level along the equator over 60
◦ of longitude in April–May 1980
(Knox and Halpern, 1982). This pulse propagated at the phase speed expected for
a first baroclinic mode equatorial Kelvin wave and constituted the first compelling
evidence for the existence of a key building block in Wyrtki’s theory for El Ni˜ no.
3
DRIFTING THERMISTOR CHAINS, PART I
My Ph.D. dissertation in 1980 was on theories of equatorial ocean circulation, including the effects of mean flows like the Equatorial Undercurrent on equatorial Kelvin
waves. However, late in my graduate studies and as a postdoc at the National Center
for Atmospheric Research (NCAR), I became interested in observational analyses and
observing system development. Francis Bretherton and Eric Kraus entrained me in a
feasibility design study for the “CAGE” experiment, an international effort intended
to measure the heat balance of the North Atlantic from the top of the atmosphere to the
bottom of the ocean (Bretherton et al., 1984). The design study identified significant
challenges, especially for estimating atmospheric heat flux divergences, which would
make it difficult to compute the balance within specified error tolerances (Bretherton
et al., 1982). CAGE (not an acronym but intended to describe the volume over which
measurements would be made) was thus never carried out, though it did influence
later design of the World Ocean Circulation Experiment (WOCE).
As an offshoot of my involvement in CAGE, Eric Kraus introduced me to
Jose Gonella of the Museum of Natural History in Paris, principal investigator of a
drifting thermistor chain project as part of the Programme Fran¸ cais Oc´ ean et Climat
dans l’Atlantique Equatorial (FOCAL). FOCAL was a French complement to the
Seasonal Response of the Equatorial Atlantic (SEQUAL) program, a U.S. initiative
to study the seasonal cycle of the tropical Atlantic over a 2-year period from 1982 to
1984. Jose was interested in developing a deployment strategy for the FOCAL drifters,
and asked whether we could use the same techniques we developed for CAGE for this
purpose. It was our opinion that we could and I volunteered to work on the problem.
I subsequently spent March–April 1982 in Paris and Brest collaborating with French
3 An El Ni˜ no did not develop in 1980 because there was no prior large-scale accumulation of excess upper
ocean heat content along the equator, which is required in addition to the excitation of equatorial Kelvin
waves for El Ni˜ no onset (Wyrtki, 1985; Cane et al., 1986).