94
Michael J. McPhaden
months to years while they analyzed their data for publication. Easy access to and
widespread use of TAO data, however, not only rapidly advanced communitywide
scientific objectives, but also created vocal constituencies who advocated on behalf
of the array’s development, continuation, and later expansion.
TAO data have supported research efforts of scientists around the world, contributing to 30–50 publications per year in the refereed literature since the array
was completed 1994. Most TAO-related publications have focused on seasonal-tointerannual time scale variability. However, the data have also supported studies of
turbulent mixing, internal waves, and the diurnal cycle at one extreme of the frequency
spectrum and decadal variability at the other extreme. As one example of scientific
progress stimulated by the array, we have learned that equatorial Kelvin waves, whose
first detection in the NORPAX/EPOCS moored time series data almost 25 years ago
represented such a significant milestone, are a common feature of variability in the
equatorial Pacific (Figure 6.3). These waves are most prominent at intraseasonal time
scales (periods of 30–120 days) and are forced in the western Pacific by westerly wind
bursts, the Madden–Julian Oscillation (Madden and Julian, 1994), and other forms of
synoptic scale weather variability. Comprehensive basin scale observations of Kelvin
waves have greatly improved our understanding of their dynamics and their influence
on the development of El Ni˜ no events (Kessler, 2005).
Despite recent advances though, many questions remain unanswered about the
nature of El Ni˜ no, La Ni˜ na, and the ENSO cycle between warm and cold events in
the tropical Pacific. Specific dynamical linkages between intraseasonal atmospheric
forcing and ENSO, the irregularity of the ENSO cycle, the limits of ENSO predictability, the decadal modulation of ENSO, and the impacts of global warming on ENSO are
among some of the outstanding unresolved issues (McPhaden, 2004; van Oldenborgh
et al., 2005). Thus, far from being a solved problem, fundamental gaps in our knowledge about the ENSO cycle continue to challenge the scientific community today.
CONCLUSION
The TAO array provides one example of how research can guide the development
of an ocean observing system for climate. It also demonstrates the feasibility of
successfully sustaining an ocean observing system developed by research scientists
over many years for climate purposes. In particular, TAO and its antecedent programs
(e.g., EPOCS and NORPAX) span nearly three decades. The 0
◦ , 110
◦ W time series,
originally started during EPOCS in 1979 and later continued as part of TAO, is now
the longest moored time series in the world ocean.
The TAO array has continued to evolve over time, taking advantage of advances in scientific understanding, new measurement technologies, and the Internet
revolution for data display and dissemination (http://www.pmel.noaa.gov/tao/ ).
Partnerships to maintain the array have likewise evolved with time. TAO is now
Michael J. McPhaden
months to years while they analyzed their data for publication. Easy access to and
widespread use of TAO data, however, not only rapidly advanced communitywide
scientific objectives, but also created vocal constituencies who advocated on behalf
of the array’s development, continuation, and later expansion.
TAO data have supported research efforts of scientists around the world, contributing to 30–50 publications per year in the refereed literature since the array
was completed 1994. Most TAO-related publications have focused on seasonal-tointerannual time scale variability. However, the data have also supported studies of
turbulent mixing, internal waves, and the diurnal cycle at one extreme of the frequency
spectrum and decadal variability at the other extreme. As one example of scientific
progress stimulated by the array, we have learned that equatorial Kelvin waves, whose
first detection in the NORPAX/EPOCS moored time series data almost 25 years ago
represented such a significant milestone, are a common feature of variability in the
equatorial Pacific (Figure 6.3). These waves are most prominent at intraseasonal time
scales (periods of 30–120 days) and are forced in the western Pacific by westerly wind
bursts, the Madden–Julian Oscillation (Madden and Julian, 1994), and other forms of
synoptic scale weather variability. Comprehensive basin scale observations of Kelvin
waves have greatly improved our understanding of their dynamics and their influence
on the development of El Ni˜ no events (Kessler, 2005).
Despite recent advances though, many questions remain unanswered about the
nature of El Ni˜ no, La Ni˜ na, and the ENSO cycle between warm and cold events in
the tropical Pacific. Specific dynamical linkages between intraseasonal atmospheric
forcing and ENSO, the irregularity of the ENSO cycle, the limits of ENSO predictability, the decadal modulation of ENSO, and the impacts of global warming on ENSO are
among some of the outstanding unresolved issues (McPhaden, 2004; van Oldenborgh
et al., 2005). Thus, far from being a solved problem, fundamental gaps in our knowledge about the ENSO cycle continue to challenge the scientific community today.
CONCLUSION
The TAO array provides one example of how research can guide the development
of an ocean observing system for climate. It also demonstrates the feasibility of
successfully sustaining an ocean observing system developed by research scientists
over many years for climate purposes. In particular, TAO and its antecedent programs
(e.g., EPOCS and NORPAX) span nearly three decades. The 0
◦ , 110
◦ W time series,
originally started during EPOCS in 1979 and later continued as part of TAO, is now
the longest moored time series in the world ocean.
The TAO array has continued to evolve over time, taking advantage of advances in scientific understanding, new measurement technologies, and the Internet
revolution for data display and dissemination (http://www.pmel.noaa.gov/tao/ ).
Partnerships to maintain the array have likewise evolved with time. TAO is now