Paper 18 



DATA ANALYSIS 



To portray the variation of the Shelf Water frontal position/ 

 distances were measured to the front along 12 standard bearing 

 lines from selected coastal points (Fig. 18.2). These bearing 

 lines intersect the 2C0-(n isobath at reqular intervals (about 

 150 km) and are approximately perpendicular to it. The distances 

 Tieasured f ro.n each satellite chart are corrected for scale 

 variation (+ or - 5%) from chart to chart and converted to 

 kilometers. These distances are then reduced by the distance 

 ^Lono each bearing line to the 20C-m isobath. The resulting 

 values represent the distance from the shelf edge/ as defined by 

 the 2CC-m isobath/ to the front/ positive values are seaward 

 from this isobath. 



Also/ a measurement of the intrusion of Slope Water over Georges 

 3ank was produced by measjring the area covered by the Slope 

 Water on an overlay of the 200-m isobath. For this calculation/ 

 Georges Bank was defined as the area of the bottom at a depth 

 <2C0 n and east of 69w in the Georges Bank region. The 

 intrusions are expressed as a percentage of the Georges Bank area 

 covered by Slope Water. Chart to chart scale variations are 

 partly compensated for by using various scaled overlays. 



WEEKLY FRCNTAL POSITIONS 



Inspection of the weekly frontal positions along a bearing line 

 c^n suggest occurrences of excursions or intrusions and general 

 spatial and temporal trends. Comparison between adjacent bearing 

 lines allows the identification of events which affect more than 

 one bearing line. Inspection of the individual weekly charts 

 suggests possible causes such as Gulf Stream meandering or warm 

 core eddies. The discussion of the different bearing lines is 

 broken up into three regions: New 

 Southern/ in order to simolify 

 evidence in the data/ ho«jever/ 

 different gr'^ups. 



England/ Middle Atlantic/ and 



discussion. There is some 



of cohesiveness among the 



New En>iL.and - The three northernmost bearing lines 

 originating from Casco Bay/ l^F/ extend into the 

 large amplitude Gulf Stream meandering and 

 eddy production cause large fluctuations in 

 position. Since the length scales of 

 generally equal to or less than twice 

 oearing lines/ this can lead to a biasing 

 consequent misinterpretation. Consider/ 

 February-Inarch period on the C?sco 

 of Casco Bay 12 indicates an 

 beginning of I'larch. The graph of 



(Fig. 18.3)/ 



region where 



warm and cold core 



the Shelf Water front 



these phenomena are 



the separation of the 



of the data and 



for example/ the 



Bay bearing lines. The graph 



intrusion which peaks at the 



Casco Bay 143 indicates an 



302 



