BJ0RN HELLAND-HANSEN 



[rep. of the "MICHAEL SARS" NORTH 



and the air has been treated in this way. Values which 

 were lacl<ing have been interpolated. We have four 

 different series, viz: 



I. June 3—13 from the area S. of the Azores. The 

 observations commenced at about 30° N, 29° W. At 

 first the route lay westward to about 35° W on June 5 

 (at Stat. 51) and then, from June 7, in a north-easterly 

 direction towards Fayal. 



II. June 17 to July 2 from the Azores WSW to the 

 Sargasso Sea (Stat. 64 on June 24) and thence northwards 

 to Newfoundland. 



III. July 8—29 from Newfoundland to. the British 

 Isles (through the Irish Sea to Glasgow). 



IV. August 4—15 from Glasgow to Rockall, thence 

 to the Faeroe-Shetland Channel (where two cross sections 

 were worked), and finally to Bergen. 



The values of m^^^{\ox the surface temperature) or 



/« (for the other elements) are represented graphically 

 in the figures A on pp. 76^ 78''^ 80*, and 82*. The curves 



B show the differences /b—/7?2^ 2)3 °'' ('^^"hi^)?,' 



The 



original differences have been smoothed out by taking 

 continuous means for 3 successive values in order to eli- 

 minate many disturbing accidental variations. 



In these figures 57oo denotes the surface salinity, 

 f the surface temperature, r the air temperature, 1 ^_^ 



the temperature difference between water and air, H^^^ 



the absolute humidity (in grams per cubic metre), H'^jo the 

 relative humidity, C the cloudiness, and W the wind. In 

 the figures A the dotted curves W represent the 24-hour 

 means ("1^22) °^ velocity in "half Beaufort" (0—6). The 

 arrows are vectors, giving the true (not magnetic) direction 

 and the velocity for each individual observation. The 

 ordinate represents the south— north direction; the 

 vector-scale of velocity is half the scale for the dotted 

 curve (the latter is given to the left in the figures). Calm 

 weather is denoted by a cross. At the top of the figures 

 A will be found some signs representing rain (small vertical 

 lines) and fog (horizontal lines). 



For a discussion of the variations in the surface-water 

 and the air it is important to know the meteorological 

 conditions over a wide area. The synoptic charts referred 

 to above (edited by the Danish Meteorological Institute 

 and the Deutsche Seewarte) give sufficient information. 

 Parts of these charts are reproduced along with the curves 

 mentioned. They refer to the morning observations made 

 by many ships and land-stations. In the reproductions 

 will be found data for wind direction and velocity (calm 

 weather denoted by a ring or a dot), air temperature (in 

 whole degrees centigrade, written in heavy type), and 

 sea temperature (in tenth degrees, written in slender type). 



The air pressure is represented by the isobars for every 

 5 mm. Fog is denoted by three short horizontal lines. 

 The representation of cloudiness (rings more or less 

 blackened) is very uncertain as in many cases it is impossible 

 to recognize it in the original publication, owing to lack 

 of clearness in the printing. The position of the 

 "Michael Sars" at 8 a.m. is marked by a cross in each 

 chart. The first chart in each series shows the position 

 of the various "Michael Sars" stations, and the dates when 

 they were occupied. 



The individual observations given in these charts are 

 of very unequal value, and many of them are possibly 

 or even certainly wrong. Provided, however, that we avoid 

 paying too much attention to the individual delails and 

 that we chiefly study the grouping of the general features, 

 we can derive from these reproductions practically all the 

 information necessary for our purpose. 



6. The Surface Salinity. 



The general variations in surface salinity along the 

 route of the "Michael Sars" will be seen from the A-curves 

 marked S°Uo, pp. 76*, 78*, 80*, and 82*. These salinity 

 curves have a very even shape with quite small bends, 

 except in some few places. The general geographic 

 features stand out clearly, with small variations within 

 each hydrographically defined region and with large 

 variations at the transitions from one region to another. 

 In the first series (p. 76*) it is a conspicuous feature that 

 the salinity had a high value near the Sargasso Sea, slightly 

 decreasing northwards to the Azores. The second series 

 shows slight variations from the date of start from the 

 Azores up to June 25th. On June 26th the salinity fell 

 rapidly for a short distance, when the route had passed 

 from the "Gulf Stream" into a "bight" of colder and less 

 saline water influenced by the Labrador Current from the 

 north. From the 27th to the 28th of June the "Michael 

 Sars" went first southwards and then northwards again 

 within the "Gulf Stream" area with high salinities. The 

 ship finally left this area on June 29th, and passed into 

 the waters coming from the north along the Newfoundland 

 Banks. The third series (p. 80*) shows the low salinities 

 of the Newfoundland waters (the left side of the curve) 

 and of the coastal waters near the British Isles (to the 

 right), with a long intervening streak of uniform waters 

 with the high salinities characteristic of the "Gulf Stream". 

 Finally, the curve of the last series (p. 82*) indicates 

 the variations in salinity on the passage from the coastal 

 waters near Scotland to the area of the Atlantic current 

 (to the left in the figure), and from the continuation of the 

 same current in the Norwegian Sea to the coastal waters of 



