vided ranges to icebergs for photomapping. 

 The anchored reference buoy used in the ice- 

 berg-drift studies was a Geodyne Corp. toroidal 

 fiberglass buoy equipped with a mast and an 

 antenna array, and moored with a bridal, 

 swival, ballast ball, 120 fathoms of 1-inch 

 braided nylon, 1 shot (15 fathoms) of 1/2 -inch 

 anchor chain and a 75-pound Danforth anchor. 

 A SST-119X solid state radar transponder 

 manufactured by Motorola Inc. was attached 

 to the reference buoy to facilitate tracking of 

 the iceberg during drift studies. The drogues 

 used in the iceberg-drift project consisted of 

 28-foot cargo parachutes suspended at 10 or 

 70 meters depth from a buoy made of inner- 

 tubes and a bamboo pole with a radar reflector 

 and a light. A similar type of moored buoy 

 acted as a reference marker in some of the 

 iceberg-drift studies, and marked the western 

 end of standard section A3 in the time-series 



studies. 



Loran A and C, visual fixes, celestial fixes, 

 and dead reckoning were the navigational meth- 

 ods used. A bottom current speed-direction re- 

 corder manufactured by Cm- Company was 

 used on some of the iceberg-drift studies. 



A PDP-8/S digital computer manufactured 

 by the Digital Equipment Corp. was used to 

 process all observed data at sea. The tempera- 

 ture and salinity data at each station were 

 processed by computer using methods discussed 

 by O'Hagen (1964), Morse and O'Hagen 

 (1964) and Kollmeyer (1964) to obtain values 

 of sigma-t and dynamic height anomaly at de- 

 sired depths. Using the method discussed by 

 Kollmeyer (1967), the volume flow was com- 

 puted with respect to the 1,000-meter level 

 through solenoids which subdivide a property 

 section into small rectangles. The average sole- 

 noidal temperature and salinity were also 

 calculated. When the STD recorder was in- 

 operative, the computer was used to correct 

 reversing thermometers, determine thermom- 

 etric depth, and calculate salinity from sali- 

 mometer data. 



The data presented in the Tables of Oceano- 

 graphic Data are from computer printouts 

 returned to the Oceanographic Unit from the 

 National Oceanographic Data Center (NODC), 

 Washington, D.C. Interpolation to standard 

 depths has been done by NODC. 



DISCUSSION 



In general the physical oceanography of the 

 Grand Banks area during the spring and 

 summer of 1967 appears to follow the pattern 

 of previous years. Figures 2, 4, and 6 are 

 charts of the average dynamic topography of 

 the surface in the area off the Grand Banks for 

 April, May, and June, based on 22 years' ob- 

 .servations (Soule, 1964). In these normal 

 charts the steepest dynamic gradients have 

 been smoothed somewhat in the averaging 

 process. The charts indicate that, although the 

 general circulation in the area remains basic- 

 ally the same, there are seasonal fluctuations 

 in the current system. A conspicuous feature 

 of the system, see figure 2, is the Labrador 

 Current which flows southward along the east- 

 ern edge of the Grand Banks toward the area 

 of the Tail of the Banks, and then dies out as 

 it continues westward or recurves to the north- 

 east. A dynamic trough lies east of the Labra- 

 dor Current ; between this trough and the high 

 dynamic stand of the meander-like intrusion 

 of the Atlantic Current Water, mixed Atlantic- 

 Labrador Current water flows northeastward. 

 North of the Atlantic Current intrusion there is 

 an eastward flow from further north. 



During May, the normal surface topography 

 exhibits an increase in dynamic height on the 

 Banks as shown in figure 4. This is generally 

 related to the arrival of less saline water as- 

 sociated with spring runoff and ice melt. The 

 change in the dynamic height in the trough is 

 less than the change on the Banks, so there is 

 an increase in current speed in May. A second 

 notable change, shown in figure 6, occurs in 

 June when the dynamic trough tends to fill 

 somewhat. This is associated with the recurva- 

 ture of the water which was off the Banks in 

 May, and it results in a lessening of the flow 

 of the Labrador Current. 



Figures 1, 3, and 5 are the charts of dynamic 

 topography for the calibration surveys made in 

 April, May, and June respectively. A com- 

 parison of the April survey and the normal 

 topography shows a slight shift of the Labra- 

 dor Current on the Grand Banks, and an ap- 

 parent shift of the meander centered at 42° N. 

 45.5° W. toward the west. The calibration sur- 

 vey for May shows a strong crowding of the 



