FY 2002

The El Niño/Southern Oscillation (ENSO) Observing System

McPhaden, M.J., T. Delcroix, K. Hanawa, Y. Kuroda, G. Meyers, J. Picaut, and M. Swenson

In Observing the Ocean in the 21st Century, Australian Bureau of Meteorology, Melbourne, Australia, 231–246 (2001)

This paper reviews contributions of the El Niño–Southern Oscillation (ENSO) Observing System to improved detection, monitoring, forecasting, and understanding of ENSO-related climate swings, with emphasis on the 1997–98 El Niño and subsequent La Niña. Highlights include detecting the rapid onset and sudden demise of the 1997–98 El Niño, initializing and verifying ENSO model forecasts, and documenting the importance of intraseasonal timescale variations in affecting the evolution of the ENSO cycle. The case is made for continuation of the ENSO Observing System for the foreseeable future, subject to possible adjustments in sampling strategies to optimize performance. In addition, recommendations are advanced to enhance the observing system with more salinity, ocean velocity, and surface flux measurements. Expansions into the Indian Ocean and higher latitudes of the North and South Pacific are also recommended based on the possible influences of those regions on ENSO variability and predictability.