1998 Year of the Ocean Impacts of Global Climate Change 



global impact of ENSO studies, and by the establishment of an ocean observing system 

 (primarily in the Pacific) for initializing and verifying models for ENSO prediction. 



The in situ observing system in the Pacific Ocean improved dramatically during the 

 1985-94 Tropical Ocean Global Atmosphere (TOGA) period (see Figure 5). The most important 

 component of this system is the National Oceanic and Atmospheric Administration (NOAA) 

 Pacific Marine Environmental Laboratory (PMEL) Tropical Atmosphere Ocean (TAO) moored 

 buoy array which provides basin- wide real-time measurements of surface and subsurface ocean 

 temperature and surface atmospheric winds. These data are augmented by other in situ 

 observations of these same quantities plus additional variables such as upper level atmospheric 

 winds, sea level, and sea level pressure. In addition, remotely sensed observations systems from 

 geostationary and polar environmental satellites give true global coverage of many atmospheric 

 and oceanic variables. The present observing system is a fully multinational effort which is 

 supported by more than two dozen countries. 



Models used in ENSO prediction range from purely statistical models to fiilly coupled 

 dynamic ocean-atmosphere models. Most of the experience in dynamical forecasting is based on 

 an intermediate class of models which simulate only climate differences from normal in order to 

 avoid problems with model climate drift. Some of the simpler models do not make full utilization 

 of all the available data. The more complex coupled general circulation models make better use 

 of the available data and are producing superior ENSO forecasts. 



Many developing countries are strongly affected by ENSO episodes because their 

 economies are dependent upon agricultural sectors as a major source of food supply, 

 employment, and foreign exports. In these countries, droughts predicted up to several months in 

 advance, coupled with the response of local farmers, have already contributed to maintenance of 

 food supplies. For example in the Brazilian state of Ceara, agricultural officials used the 

 predictions of the 1991-92 EL Nino to change the timing and types of crops planted. That year 

 Ceara had harvests at near normal levels compared to the massive crop failures experienced 

 during the 1986-87 El Nino. 



For procedures such as these to work, it is desirable to have full and open access to data 

 and analysis products among all participating nations, organizations, and institutions. In some 

 cases, national security interests restrict the exchange of information. Moreover, a weakness of 

 ENSO investigations is the limited cooperation among interdisciplinary groups. For example, 

 coupled ocean-atmosphere models include analyses of ocean temperature, salinity, and currents. 

 These data fields would be useful to biologists who wish to understand impacts of ENSO on the 

 distribution of marine species. 



The Tropical Ocean Global Atmosphere Program concentrated on ENSO with great 

 success. However, other interannual signals in other tropical oceans and at high latitudes were 

 ignored. For example, changes in the tropical Pacific account for only part of the variability 

 observed over North America in temperature and precipitation. There are also emerging efforts to 

 understand the variability and predictability of the American and the Asian- Australian monsoon 



G-14 



