84
Michael J. McPhaden
colleagues on a design study that considered alternative drifter deployment strategies
targeted at improving estimates of the seasonal cycle in heat storage for the tropical
Atlantic (McPhaden et al., 1984). Guided by this study, we later deployed an array of
19 drifters, each equipped with a 117-m-long thermistor chain, between June 1983
and May 1984 (Reverdin and McPhaden, 1986).
The design study that guided the FOCAL drifting buoy deployment strategy
was initiated coincident with the eruption of the Mexican volcano El Chichon and the
stealthy onset of what would eventually be the strongest El Ni˜ no in 100 years. The
1982–83 El Ni˜ no proved to be not only a watershed event in the history of climate
research, but also a major turning point in my career.
THE 1982–83 EL NI ˜
NO
The 1982–83 El Ni˜ no, which was neither predicted nor even detected until nearly at
its peak, caught the scientific community completely by surprise. At the time, most
in situ oceanographic data collected were available only many months or, in some
cases, years after collection. Some data on oceanic and atmospheric conditions from
islands and volunteer observing ships were available in real time (within a day) or
near real time (within a month for climate purposes), but they were far too few and
scattered to be of much value in providing a coherent picture of evolving conditions.
NOAA satellites capable of high-precision measurements of SST from space had
been launched for the first time in 1981. However, unbeknownst to NOAA, SST
retrievals after March 1982 were contaminated by stratospheric aerosols from the
eruption of El Chichon. The aerosols produced a cold bias in the satellite SSTs that
was mistakenly interpreted as clouds. These biased retrievals were flagged as bad and
replaced with climatology in gridded analyses of the data. Thus, throughout much
of 1982, SST analyses based on satellite data indicated near normal conditions in
tropical Pacific. Moreover, those few in situ data that showed extraordinarily warm
SSTs several degrees Celsius above normal were rejected as erroneous because they
did not agree with the satellite analyses.
To complicate matters, the community at the time had an overly simplistic view
of how El Ni˜ no evolved. Wyrtki (1975) had noted the tendency for the trade winds to
strengthen and the sea level to build up in the western Pacific the year before El Ni˜ no.
Rasmusson and Carpenter (1982) had also just published a composite of El Ni˜ no
based on events from 1950 to 1973, which showed that typically anomalous warming
progressed in stages from the west coast of South America in boreal spring to the
central Pacific later in the year. None of these “canonical” developments occurred
in 1982, lulling much of the community into the false belief that conditions in the
tropical Pacific were near normal. Indeed, Klaus Wyrtki commented at a meeting of
oceanographers and meteorologists at Princeton University in October 1982 that, “To
call this an El Ni˜ no would be a case of child abuse!” It was only after scientists on a
research cruise to the eastern Pacific reported that same month that the thermocline
Michael J. McPhaden
colleagues on a design study that considered alternative drifter deployment strategies
targeted at improving estimates of the seasonal cycle in heat storage for the tropical
Atlantic (McPhaden et al., 1984). Guided by this study, we later deployed an array of
19 drifters, each equipped with a 117-m-long thermistor chain, between June 1983
and May 1984 (Reverdin and McPhaden, 1986).
The design study that guided the FOCAL drifting buoy deployment strategy
was initiated coincident with the eruption of the Mexican volcano El Chichon and the
stealthy onset of what would eventually be the strongest El Ni˜ no in 100 years. The
1982–83 El Ni˜ no proved to be not only a watershed event in the history of climate
research, but also a major turning point in my career.
THE 1982–83 EL NI ˜
NO
The 1982–83 El Ni˜ no, which was neither predicted nor even detected until nearly at
its peak, caught the scientific community completely by surprise. At the time, most
in situ oceanographic data collected were available only many months or, in some
cases, years after collection. Some data on oceanic and atmospheric conditions from
islands and volunteer observing ships were available in real time (within a day) or
near real time (within a month for climate purposes), but they were far too few and
scattered to be of much value in providing a coherent picture of evolving conditions.
NOAA satellites capable of high-precision measurements of SST from space had
been launched for the first time in 1981. However, unbeknownst to NOAA, SST
retrievals after March 1982 were contaminated by stratospheric aerosols from the
eruption of El Chichon. The aerosols produced a cold bias in the satellite SSTs that
was mistakenly interpreted as clouds. These biased retrievals were flagged as bad and
replaced with climatology in gridded analyses of the data. Thus, throughout much
of 1982, SST analyses based on satellite data indicated near normal conditions in
tropical Pacific. Moreover, those few in situ data that showed extraordinarily warm
SSTs several degrees Celsius above normal were rejected as erroneous because they
did not agree with the satellite analyses.
To complicate matters, the community at the time had an overly simplistic view
of how El Ni˜ no evolved. Wyrtki (1975) had noted the tendency for the trade winds to
strengthen and the sea level to build up in the western Pacific the year before El Ni˜ no.
Rasmusson and Carpenter (1982) had also just published a composite of El Ni˜ no
based on events from 1950 to 1973, which showed that typically anomalous warming
progressed in stages from the west coast of South America in boreal spring to the
central Pacific later in the year. None of these “canonical” developments occurred
in 1982, lulling much of the community into the false belief that conditions in the
tropical Pacific were near normal. Indeed, Klaus Wyrtki commented at a meeting of
oceanographers and meteorologists at Princeton University in October 1982 that, “To
call this an El Ni˜ no would be a case of child abuse!” It was only after scientists on a
research cruise to the eastern Pacific reported that same month that the thermocline