Early in the planning for MODE, it was evident that additional 

 information was required on mesoscale eddies, so a first observa- 

 tional effort — ^MODE-O — was initiated. MODE-O took place from 

 November 1971 to March 1972. 



MODE-I is scheduled for March-July 1973. Five or six ships are 

 expected to take part. Eighty current meters will be suspended from 

 25 moorings arranged in a circular pattern with the meters concen- 

 trated at 500-, 800-, 1.500-, and 3,000-db levels plus a deep level 

 located either 100 m above bottom on the abyssal plain or 4,000 m 

 above rough abyssal hill terrain. Complementary observations will 

 include tracking SOFAR (sound fixing and ranging) and Swallow 

 floats, bottom pressure measurements, vertical profile (salinity-tem- 

 perature-depth, current velocity) measurements, and transport 

 measurements, and transport measurements from aircraft. 



MODE-II will depend on MODE-I results, the results of the 

 U.S.S.R. large buoy array experiment, and international confer- 

 ences. Constraints include the need for a 1- or 2-year time series, 

 an extensive array, and international cooperation. MODE-II is ten- 

 tatively scheduled for 1976 and 1977. 



Projects for the MODE studies are: 



Project Title 



Current Meter Arrays for MODE. 



Moored Array Studies. 



Investigation of Interactions Be- 

 tween Short Internal Gravity Waves 

 and Larger Scale Motions in the 

 Ocean. 



MODE: Observations of an Isopropyl 

 Surface. 

 SOFAR Float Experiment. 



SOFAR Float Listening Station. 



Vertical Profiles of Horizontal 

 Currents. 



A Theoretical-Numerical Study of 

 Geostrophic Eddy Motions in the 

 Ocean. 



Flat and Inverted Echo Sounder Ex- 

 periments for MODE. 



Figure 22 shows the location of the MODE-1 Field project As 

 of May 1972, no field work other than gear trials has been con- 

 ducted. Serial stations and STD measurements were obtained by the 

 RV Trident on Cruise 105 in November 1971 and Cruise 107 in 

 December 1971. Current-meter arrays were set out near 30°N., 

 70°W., by the RV Trident on Cruise 104 during October and No- 

 vember 1971 and retrieved on Cruise 109. 



25°- 



20°- 



15°- 



10°- 



85° 



/5° 



70° 



65° 



60° 



Aircraft as Part of the MODE Experi- 

 ment. 



FIGURE 22.— Location of MODE-1 Field Experi- 

 ment. 



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