Milestones on the Road toTOGA

The motivation for TOGA came during the 1970s as the central importance of the newly discovered ENSO phenomenon linking the equatorial Pacific Ocean with interannual global climate variability became apparent. It began in 1969 with the publication of a seminal paper by Jacob Bjerknes in which he identified a pattern of wintertime North Pacific atmospheric teleconnections that were associated with the appearance equatorial Pacific interannual warming events. Furthermore,, he recognized that the North Pacific atmospheric anomaly pattern was part of the global Southern Oscillation discovered by Gilbert Walker in the 1920s. Prior to Bjerknes's publication many meteorologists were skeptical of Walker's findings, which were based only on statistical analysis. Walker offered no explanation for the oscillation and thus it could well be just a statistical artifact of his relative short time series. Bjerknes study provided the causal link!

Most of the followup studies of this phenomenon during the next decade were split between addressing the separate issues relating to (a) the question of the atmospheric response to prescribed equatorial SST anomalies and (b) the equatorial Pacific Ocean response to prescribed surface wind anomalies. The coupled system was yet to receive much attention. However significant advances were made during this period in the description and understanding of the equatorial ocean forcing by the atmosphere. Particularly noteworthy was the research and intellectual leadership of Klaus Wyrtki leading to a better understanding and modelling of the the effects of westerly wind burst forcing of the ocean in the equatorial belt that generate eastward propagating oceanic Kelvin waves. Klaus also recognized the oscillating phases of the phenomenon between a "buildup" period (La Nina?)and onset of warm episodes as an indication of potential predictability. He hypothesized that a buildup phase was a necessary condition prior to a warm episode. Unfortunately this scheme did not verify for the major but somewhat anamolus 1982-83 warm event.

An advance toward a more interdisciplinary framework for studying ENSO took place in the mid-1970s with the establishment of the NOAA Equarorial Pacific Ocean Climate Studies (EPOCS), led by Joe Fletcher. Joe clearly understood that resources were not available for a comprehensive global ocean study. Instead, he choose to focus on the better posed and more limited ocean-atmosphere feature that Bjerknes' research had revealed. EPOCS researchers included both meteorologists and oceanographers from within and outside NOAA, and Inirial differences in culture had to be overcome, but we ultimately learned to communicate. EPOCS continued as a separate but tightly integrated program during TOGA. On a personal note, just as the EPOCS program was getting underway, Rob Quayle called me from the National Climate Data Center to inform me that he had finished assembling a new, quality-controlled and comprehensive surface marine data set. These data turned out to be the primary source of information for our subsequent EPOCS analyses, including the development of the canonical description of a warm episode evolution. MANY THANKS, ROB!!!

A significant confluence of new research results, international program development, and the recognition that ENSO is a major feature of interannual climate variability, occurred around 1980. Internationally, the Global Atmospheric Research Program GARP) was winding down. Furthermore,as a result of the 1979 World Climate Conference, a new World Climate Research Program (WCRP) was established, and a strong initial flagship research focus was needed to initiate the program.

The 1980 Starr Memorial Lecture given by Mike Wallace at MIT turned out to be a crucial element in the sequence of events leading to the establishment of TOGA. Mike presented the yet unpublished results of his study with Horel that revealed the North Pacific PNA teleconnection as a feature forced by equatorial Pacific precipitation anomalies forced in turn by equatorial warming. He further related these findings to our yet unpublished canonical description of the evolution of a warm event.

Mike's lecture was attended by an all-star cast of scientists and planners that included Charney, Lorenz snd Smagorinsky, who had been appointed Chair Of the WCP Joint Organizing Committee (JOC). One week later, the same group attended the GFDL 25th anniversary celebration in Princeton. Mike's lecture the week before was a major topic of discussion. In his summary of prime research topics which needed to be pursued, Charney singled out the yet-to-be named ENSO phenomenon as a prime overlooked feature of the climate system that needed to be more aggressively addressed.

A few weeks later, Smagorinsky asked me for a draft of our paper on the canonical warm event that he could carry with him to an upcoming meeting of the JOC. He returned with the news that a new WCRP program named TOGA had been established, with a major focus on what they referred to as ENSO. His comment to me was "If I were a young lad, this would be the topic I would be working on."