420-m temperature and 

 current velocity 4-dav 

 mean; T-Ps and current 

 meters. 



10 cm/sec = I— I 



500-m temperature 12 day 

 mean; CTDs. 



1,500 m current streamlines; 

 SOFAR floats and current 

 meters — instantaneous. 



10 cm/sec = 



3,000-m temperature and 

 current velocity 12 -day 

 mean; CTDs and current 

 meters. 



10 cm/sec 



Scale: 100 km 



1 — I -J, I — I — I — I — 1\ 



^, 93-104 



16.25 



I I I I I " 



-I — I — r^T — I — I — r 



2.75 



93-104 



2.8 - 



I I I I I L. 



,14 5/))N'! ^^141-152 



■■ ^ -2.75-^'' ^ 



52 



I I 1^1 I I 



J I I I I I L 



Figure 1. — MODE-I temperature and current patterns at selected depths and intervals of several weeks. Grid is centered at 

 28 N, 69 40'W. 



Elements of U.S. Core Program 



( 1 ) Statislical-Geographical Experiment. The backbone of 

 this experiment is a consecutive series of three arrays of moored 

 instrumentation in the western North Atlantic: Array I, 7 

 moorings, starting July 1974, for 9 months; Array II, 12 

 moorings, starting April 1975, for 27 months; and Array III, 

 14 moorings, starting July 1977, for at least 12 months. These 

 arrays are located in different regions (one to the east of the 

 Mid-Atlantic Ridge), and designed to embrace a range of 

 scales. They will carry VACM current meters, and T/P re- 

 corders (for measurement of current, temperature, and pres- 

 sure). Data for statistical analysis will also be available from 

 the Northern and Southern Local Dynamics Experiments. 



Specially obtained XBT sections will also be made over a 

 wide region of the North and South Atlantic for better resolu- 



tion of geographical variability of the eddy field as seen in the 

 upper-layer temperature field. 



(2) Local Dynamics Experiment: Southern Synoptic Experi- 

 ment. In the spring of 1977, probably over the Nares Abyssal 

 Plain (north of Puerto Rico), a program of mapping of the 

 eddy field will be conducted over an area about 300 km square. 

 The main instrumentation will consist of 60 free-floating, 

 neutrally buoyant (at prescribed depths) SOFAR floats at 

 two levels. After release they will float freely, being tracked 

 acoustically from land-based listening stations. They have a 

 telemetering capability for temperature and pressure and thus 

 provide a nearly real-time map of the flow field. Experience 

 with past float performance indicates that once emplaced, the 

 dispersal will allow the floats to be tracked continuously for 

 up to 3 years. During the first year they will be maintained 

 in a mapping array by recovery and resetting. 



