eastward branching of the Labrador Current between latitudes 

 46° N., and 49° N. Cold mixed water covered all of the area except 

 those margins in the southeastern part of the surveyed area where the 

 dynamic heights were greater than about 971.1 dynamic m.eters. 



Figure 16 shows the dynamic topography found dm-ing the third 

 survey. It should be borne in mind that in surveys of the Bonavista 

 triangle the middle part of the triangle is too distant from oceano- 

 graphic stations to permit of accurately estimating the details of the 

 dynamic topography there. In this particular survey there is also 

 some uncertainty as to the longitude of the southeastern section of the 

 triangle. Just prior to this occupation of the triangle an intense low 

 barometric pressure system persisted for several daj^s in the area of the 

 triangle. It was anticipated that its effect would be to weaken the 

 eastern branch of the Labrador Current and strengthen the western 

 branch. Figure 16 verifies this in part. However, this portion of the 

 current which was diverted westward toward Cape Bonavista seem- 

 ingly did not continue southward along the Avalon Peninsula but 

 recurved eastward along the northern slope of the Grand Banks. 



Only 6 days separated the last station of the third survey and the 

 first station of the fourth survey. Figures 16 and 17, therefore, are 

 more nearly two parts of the same synoptic picture than is usually 

 the case with two successive surveys. Comparison of figures 15 and 

 17 in the area between 45° N., and 47° N., shows the changes taking 

 place during the approximately 1 -month interval. The contour lines 

 took on a more regular shape in the later survey and the meanders 

 in this area seem to be less noticeable although many of the features, 

 somewhat displaced, are recognizable in each figure. At about 44° 

 N., figure 17 shows a westward incursion of Atlantic Current water 

 which accompanied the northeastward recurvature of a major part of 

 the Labrador Current north of this latitude. South of 44° N., the 

 cold mixed water pool was considerably reduced in area compared to 

 the first survey although it extended southward very nearly to 41° N. 

 The dynamic heights in margins of the Atlantic Current in the south- 

 eastern edge of the surveyed area were not as high as usual. 



The volume of flow, mean temperature, and heat transport of the 

 Labrador Current have been determxined for each of 19 sections oc- 

 cupied during the 1953 season and postseason cruises. Some of 

 these sections have been occupied in other years, and in the case of 

 sections T, U, and W, numerous occupations have provided the data 

 for determining rough approximations to normal seasonal variation 

 curves. These have been published in bulletin number 36 of this 

 series. Less is known of the seasonal variation in the Labrador 



56 



