Sextant to Satellite
159
1982 TO THE PRESENT
After 1982, progress continued at a rapid pace. To stay informed about current conditions in the tropical Pacific, at and below the ocean surface, Stan Hayes
19 deployed
the TAO array of instruments. To cope with the ever-increasing volume of data, Ants
Leetmaa
20 started using an Oceanic General Circulation Model for operational purposes, each month producing maps of conditions in the Pacific, the oceanographic
counterpart of the daily weather map. Having a seagoing oceanographer lead this activity contributed to the rapid acceptance of the GCM as a useful tool by a community
which had been largely skeptical of the value of computer models of the ocean.
Up to 1982 oceanographers were interested mainly in the response of the oceans
to changes in the winds. They attributed El Ni˜ no to an abrupt relaxation of the trade
winds. But why do the winds relax? Meteorologists argue that the winds respond to
changes in tropical sea surface temperatures, which in turn are induced by the winds.
Bjerknes
21 first realized that this circular argument—the winds are both a cause
and consequence of sea surface temperature changes—implies unstable interactions
between the ocean and atmosphere. His paper gives a remarkably clear and accurate
description of how El Ni˜ no develops, but the arguments are qualitative. Furthermore,
Bjerknes was puzzled about the processes that terminate El Ni˜ no. Why is there a
continual oscillation, the Southern Oscillation, which has El Ni˜ no as its warm phase?
(In 1985 I introduced the name La Ni˜ na for the complementary cold phase.)
Some oceanographers continued to believe that El Ni˜ no is induced by a change
in the winds (or westerly wind bursts). Others started investigating El Ni˜ no as one
phase of a continual oscillation. Mark Cane and Steve Zebiak
22 first produced a
coupled ocean–atmosphere model that spontaneously produced an interannual oscillation. The physical processes that maintain this mode were at first unclear until
Paul Schopf and Max Suarez
23 proposed that the delayed response of the ocean to
the winds, in contrast to the immediate response of the atmosphere to a change in
sea surface temperatures, is of central importance. David Neelin,
24 David Battisti,
25
and their collaborators explored the continuous spectrum of natural modes that are
possible; the delayed oscillator is but one member of the spectrum. The advances in
our ability to observe and explain the tropical oceans and their interactions with the
atmosphere were so rapid that, in June 1997, scientists were able to sound an alert that
a major El Ni˜ no was developing, and could predict that California would experience
a harsh winter six months later.
The launching of Sputnik brought constructive changes to the way oceanographers manage their activities. El Ni˜ no of 1982 brought further changes, but I found
these ones disconcerting. I became aware of this during a small meeting in Miami in
the early 1990s to plan the large, international program CLIVAR to study CLImate
VARiability. Our efforts to define focused goals for this program were stalled when
word spread through the room that help was on the way; an influential person happened
to be in town and would be joining us soon. During my previous visits to Miami to
plan programs—the GATE program for example—we often found ourselves in need
159
1982 TO THE PRESENT
After 1982, progress continued at a rapid pace. To stay informed about current conditions in the tropical Pacific, at and below the ocean surface, Stan Hayes
19 deployed
the TAO array of instruments. To cope with the ever-increasing volume of data, Ants
Leetmaa
20 started using an Oceanic General Circulation Model for operational purposes, each month producing maps of conditions in the Pacific, the oceanographic
counterpart of the daily weather map. Having a seagoing oceanographer lead this activity contributed to the rapid acceptance of the GCM as a useful tool by a community
which had been largely skeptical of the value of computer models of the ocean.
Up to 1982 oceanographers were interested mainly in the response of the oceans
to changes in the winds. They attributed El Ni˜ no to an abrupt relaxation of the trade
winds. But why do the winds relax? Meteorologists argue that the winds respond to
changes in tropical sea surface temperatures, which in turn are induced by the winds.
Bjerknes
21 first realized that this circular argument—the winds are both a cause
and consequence of sea surface temperature changes—implies unstable interactions
between the ocean and atmosphere. His paper gives a remarkably clear and accurate
description of how El Ni˜ no develops, but the arguments are qualitative. Furthermore,
Bjerknes was puzzled about the processes that terminate El Ni˜ no. Why is there a
continual oscillation, the Southern Oscillation, which has El Ni˜ no as its warm phase?
(In 1985 I introduced the name La Ni˜ na for the complementary cold phase.)
Some oceanographers continued to believe that El Ni˜ no is induced by a change
in the winds (or westerly wind bursts). Others started investigating El Ni˜ no as one
phase of a continual oscillation. Mark Cane and Steve Zebiak
22 first produced a
coupled ocean–atmosphere model that spontaneously produced an interannual oscillation. The physical processes that maintain this mode were at first unclear until
Paul Schopf and Max Suarez
23 proposed that the delayed response of the ocean to
the winds, in contrast to the immediate response of the atmosphere to a change in
sea surface temperatures, is of central importance. David Neelin,
24 David Battisti,
25
and their collaborators explored the continuous spectrum of natural modes that are
possible; the delayed oscillator is but one member of the spectrum. The advances in
our ability to observe and explain the tropical oceans and their interactions with the
atmosphere were so rapid that, in June 1997, scientists were able to sound an alert that
a major El Ni˜ no was developing, and could predict that California would experience
a harsh winter six months later.
The launching of Sputnik brought constructive changes to the way oceanographers manage their activities. El Ni˜ no of 1982 brought further changes, but I found
these ones disconcerting. I became aware of this during a small meeting in Miami in
the early 1990s to plan the large, international program CLIVAR to study CLImate
VARiability. Our efforts to define focused goals for this program were stalled when
word spread through the room that help was on the way; an influential person happened
to be in town and would be joining us soon. During my previous visits to Miami to
plan programs—the GATE program for example—we often found ourselves in need