forecasts . 



Detailed small-scale analyses are prepared for specific operation 

 areas, and can be prepared in any area if and when requested by operating 

 forces. This is done by specifying four positions (corners) of the area, 

 extracting information from the standard large-scale analyses/forecasts 

 made at FNWF and expanding it to new 63x63 grid, to which additional 

 details can be added by reanalysis . This is illustrated in Figures 11 and 

 12. The minimum (and optimum) grid size of such small-scale analysis is 

 greatly determined by data density, rate of change of properties and com- 

 plexity of local modifying factors . 



THE SPEED AND MAGNITUDE OF RESPONSE OF THE OCEAN TO THE ACTION OF 

 ATMOSPHERIC FORCES, AND THEIR EFFECTS ON OCEANOGRAPHIC ANALYSIS 

 AND FORECASTING PROGRAMS 



A number of recent synoptic studies and surveys indicate relatively 

 fast and pronounced response of surface layers of the ocean to the 

 atmospheric driving forces. The relatively rapid response of the surface 

 layers to the synoptic surface weather conditions was demonstrated with 

 synoptic sea surface temperature and surface weather analysis and time 

 series BT messages by Wolff, Laevastu and Russell (1965). They also 

 demonstrated that the sea surface temperature fluctuations have shorter 

 periods in higher latitudes in the areas of migrating cyclones and longer 

 periods in lower latitudes in the areas of highs . The magnitude of short- ' 

 term sea surface temperature fluctuation depended on its gradient and 

 could reach 4°C in 48 hours but was, on the average, about ± 0.3°Cin 

 the same period. The sea-surface temperature fluctuation patterns were 

 large in scale and corresponded to past wind fields, thus demonstrating 

 the importance of advective contribution to these changes . Numerous 

 examples of rapid response of the surface layers of the sea to the atmos- 

 pheric driving forces can be obtained daily. A few of these are given 

 below. Figure 13 shows a plot of sea surface temperature from 15 March 

 to 6 April 1965 at OSV November. The relatively sudden SST changes 

 between 23 - 24 March and 29-30 March (2 to 3°C in 24 hours) are 

 obviously mainly advective as the surface pressure charts on the same 

 figure indicate. During the period of small SST fluctuations, OSV November 

 is in a high pressure area with relatively weak winds. 



Another more complex type of rapid response of the sea to atmos- 

 pheric forces is illustrated in Figures 14 and 15. The relatively large 

 fluctuations of sea surface temperature (Fig 14A) close to a major current 

 boundary and in an area of sharp horizontal temperature gradients are 

 caused by migrating cyclones, which push the cold, less saline water 

 from the St. Lawrence Gulf over warmer more saline water (Fig 15B), as 

 already shown by Wolff, Laevastu and Russell (1965). The passing 

 cyclones cause extensive, relatively large-scale, meandering of the sur- 

 face layers, as shown in Figures 148, C and 15A. The details of this 

 process are somewhat more complex than is possible to describe here. 

 Figure 148 also shows the climatological 200 m temperature boundary, 



100 



