western North Atlantic. Rev. Geophys. Space Physics 15:385- 

 420. 



The Mid-Ocean Dynamics Experiment — MODE-I. 



1975. Dynamics and analysis of MODE-I: report of the 

 MODE-I dynamics group. 250 p. MODE-I Exec. Of., 54- 

 1417 M.I.T., Cambridge, MA 02139. 



U.S. POLYMODE Organizing Committee. 



1976. U.S. POLYMODE program and plan. Office of the 

 IDOE of the Natl. Sci. Found, and Off. Nav. Res., 87 p. 



Wunsch, C. 



1977. Determining the general circulation of the oceans: a 

 preliminary discussion. Science 196:871-875. 



North Pacific Experiment (NORPAX) 



The long-term objective of NORPAX is to understand fluc- 

 tuations in the upper layers of the North Pacific Ocean and 

 their relation to the overlying and adjoining atmosphere. These 

 fluctuations have time scales of months to years and a space 

 scale in excess of 1,000 km. Achievement of this goal should 

 lead to improved prediction of weather and climate for the 

 northeast Pacific Ocean and North America. NORPAX is work- 

 ing to attain its long-range objective through analysis of histori- 

 cal data, experiments to identify and understand important 

 processes, monitoring of low-frequency fluctuations, and inte- 

 gration of observations with theoretical and numerical studies. 



NORPAX is jointly sponsored by the IDOE section and 

 the Office of Naval Research. The principal investigators form 

 the nucleus of NORPAX (table 6). They annually elect an 

 executive committee that oversees the program, formulates plans 

 and policy, coordinates activities, and represents NORPAX 

 in dealings with the granting agencies and the scientific com- 

 munity. The five members of the executive committee select a 

 chairman, who is assisted by the program administrator. 



Most principal investigators belong to at least one of the 

 various groups and task forces formed within the program. 

 These groups are related to certain scientific problem areas 

 (Climate Studies), to specific experiments (Anomaly Dynamics 

 Study), or to important organizational tasks (Satellite Data 

 Evaluation Panel). Membership in these groups is voluntary 

 and by self-appointment; scientists who are not NORPAX in- 

 vestigators, but who are willing to contribute to the program, 

 may also be members of these groups. 



Climate Studies 



The Climate Studies seek to understand long-period, large- 

 scale changes in temperature and circulation in the North Pacific 

 and to relate these changes to variations in atmospheric cir- 

 culation. As such, these studies are basic to NORPAX in gen- 

 eral and to specific programs in NORPAX such as the Anomaly 



Dynamics Study and the Equatorial Program. This year, it has 

 been proposed that a specific Climate Program be formed within 

 NORPAX, not to dilute the other programs but to encourage 

 greater interaction and coordination among all programs in 

 support of the overall climate-related objectives of NORPAX 

 as shown in figure 19. 



In particular, the purpose of a NORPAX Climate Program 

 is to focus the data and experience on large-scale air-sea inter- 

 action, developed within NORPAX, on the role of the ocean 

 in seasonal and interannual climate variability. This program 

 will help identify the need for: 



1) procurement and processing of new climatic data sets, 



2) design of new statistical and phenomenonological studies 

 of air-sea interaction using these data, 



3) formulation of new empirical hypotheses and statistical 

 models of regional and interannual climatic variability on the 

 basis of these studies, and 



4) design and application of new dynamic models of climate 

 to test these hypotheses. 



Obtaining new data and retrieving existing data from other 

 sources are continuing processes. Much of the data is obtained 

 through ship-of-opportunity programs coordinated both by in- 

 dividual investigators and by the Fleet Numerical Weather 

 Central. 



A cooperative program with the Max Planck Institute of 

 Hamburg has resulted in a preliminary form of a generalized 

 approach to linear multivariate prediction. This technique allows 

 a quantitative estimate of the artificial predictability associated 

 with a given hindcast and has been used to predict the strength 

 of the Intertropical Convergence Zone over most of the central 

 Pacific Ocean for 6 months in advance and sea-surface tempera- 

 ture in the equatorial central Pacific to 8 months in advance. 

 Both results are significant at the 95 percent confidence level. 



Anomaly Dynamics Study 



The objective of the Anomaly Dynamics Study (ADS) is to 

 explain the origin of the large heat storage anomalies that are 

 observed in the surface layer of the Pacific Ocean. One im- 

 portant part of the program is regular monitoring, by aircraft 

 and merchant ships, of the thermal structure of the ocean's upper 

 layer in the region 30°N to 50°N, 140° W to 180° W. 



Two ADS reports have been issued, ADS-1 in October 1977 

 and ADS-2 in November 1977, and a third is in preparation. 

 These contain contour maps of the following monthly mean 

 data: Fleet Numerical Weather Central air temperature, wind- 

 speed, wind direction, surface-vapor pressure, and 700-mb 

 heights; NORPAX-calculated wind stress, wind-stress curl, 

 wind-shear velocity cubed, sensible heat flux, and latent heat 

 flux; objectively analyzed TRANSPAC temperatures at discrete 

 depths, and monthly drifter buoy displacement vectors. The 

 ADS timetable is indicated in figure 20. 



One observation of interest was the tendency for deep (300m) 

 temperature anomalies to travel westward at 20cm/s in the 

 TRANSPAC region as shown in figure 21. 



Another observation is the more active response in the west- 

 ern North Pacific as opposed to the eastern region as seen in fig- 

 ure 22. 



30 



