ATLANT. DEEP-SEA EXPED. 1910. VOL. i] PHYSICAL OCEANOGRAPHY AND METEOROLOGY 



49 



in winter cause a decrease of the annual range south-east 

 of Greenland. Tlie abnormally large range of tempera- 

 ture found off the east coast of the U. S. A. and New- 

 foundland, is primarily due to seasonal changes in the 

 position of the currents. In this area there are abrupt 

 transitions from warm to cold water and a seasonal varia- 

 tion in the relative distribution of these water masses, must 

 necessarily cause particularly marked changes in tempera- 

 tures referred to geographic co-ordinates. 



For a study of the seasonal variations in the water 

 below the surface the material of direct observations is 

 very poor. In the literature I have found from deep off- 

 shore parts of the eastern North Atlantic only 3 cases 

 where serial observations have been taken at different 

 seasons in the very same geographical position: One 

 station W of Scotland, one SW of Ireland (referred to 

 below), and one between Spain and Morocco. Each of 

 these stations which have been taken by Danish expedi- 

 tions, have been repeated once. 



During the "Thor" expedition in 1905, serial obser- 

 vations were taken at 48" 4' N. Lat. and 12° 40' W. Long, 

 on June 7th (Stat. 68) and again on September 2nd 

 (Stat. 178). The conditions are demonstrated by the 

 diagrains of temperature, salinity and depth ["T-S-(D)- 

 diagrams"] in Fig. 10. The numbers written along the 

 curves represent the depths of observation, in metres. 

 There are some differences of salinity between the two 

 series, but they are mostly small and within the limits 

 of error at 25, 400 and 1500 metres. During these 

 summer-months the temperature had increased 5-2° C at 

 the surface, 5-38^ C at 25 metres, 3-23° C at 50 metres, 

 0-40° C at 100 metres, and 0-11° C at 400 metres. By 

 means of the curve on p. 74-' we find the following 

 "salinity-anomalies" in 1/100 "/uo and "temperature-ano- 

 malies" in 1/100=' C (cf. section 18): 



35-0 %o 



35-5 %o 



Owing to the differences in salinity, mentioned above, 

 the differences in "temperature-anomaly" do not quite cor- 

 respond to those in temperature. From the last column 

 of the table we see that the variation of temperature at 



Fig. 10. Tcmperatiire-salinily-depth diagrams for the "Thor" 

 stations 68 (June 7th, 1906) and 178 (September 2nd, 1906). 



100 inetres corresponds to a fall of temperature, when we 

 take the variations of salinity into account. At 400 metres 

 the variation is quite negligible. The high values of A S 

 at depths between 800 and 1500 metres indicate a marked 

 admixture of water from the Mediterranean at the locality 

 in question. The differences from June to September 

 between the anomalies at 800—1200 metres may suggest 

 seasonal changes in the amount of Mediterranean water. 

 When we plot out on mm.-paper the temperatures 

 observed at various dates, we obtain rather a motley 

 picture of the seasonal variations, if the observations are 

 limited to a certain area of the sea, including different 



