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



75 



10 I 2 3 4 IS 6 



8 9 ?0 I 2 3 4 ?5 6 -7 8 9 3- 



Fig. 27. To the left: temperatures in situ in the bottom 

 "Challenger" E.xpedition. To the right: potcntia 



water of the North Atl.intic according to observatioMs from the 

 temperatures corresponding to the temperatures observed. 



creasing to 0-2° in the next interval of depth and to 04^ 

 at depths below 5000 metres. Similar variations are found 

 in the potential temperatures. 



With regard to the eastern part of the North At- 

 lantic the mean temperatures in situ demonstrate an 

 increase downwards which corresponds to adiabatic 

 equilibrium (unifonn potential temperatures). At fir>t 

 sight it inight seem as if the observations here revealed, 

 after all, conditions which were supposed not to be de- 

 tectable by the MiUer-Casella thermometers. Further 

 consideration, however, lead to the conclusion that this 

 apparent contradiction must be ascribed to regional 

 variations. 



The relatively high values of r,„ at depths between 

 4500 and 5000 metres and below 5000 metres are due 

 to the observations from Stats. 5—9 and 81. Probably 

 the bottom-water at these stations is influenced by water 

 from the Mediterranean. The charts from lODO and 2000 

 metres on p. 97*, demonstrating the distribution of salinity- 

 anomaly, indicate the appearance of water mixed with 

 water from the Mediterranean. As previously mentioned, 

 such mixed water causes high positive values of ^ ^. 

 The chart for 1000 metres shows maximum values in an 

 area off the coast of Portugal, north of 35° N. At 2000 

 metres the values of ^ S are lower, but the maximum 

 values appear in a belt more to the south-west, towards 



30^ N. It is very probable that the layer of A Sn,ax. 

 sinks farther to the south-west and ihni vestiges of wntcr 

 from the Mediterranean appear in tfje bottom-water as 

 far south as 25° or 20" N. Lat., and possibly still farther 

 south. The presence of this mi.xed water is indicated 

 by comparatively high temperatures and salinities, but the 

 deviation fiom the normal Atlantic conditions is more 

 pronounced in salinity than in temperature. Even if high 

 positive values of salinity-anomaly correspond to negative 

 values of temperature-anomaly, the absolute values of 

 temperature in situ are higher in such water than they 

 are in the ordinary Atlantic water to which water from 

 the Mediterranean has not been added. We shall return 

 to this point in section 38 and only note here that veiy prob- 

 ably the high values of /„, at the "Challenger" stations 

 5—9, at greater depths than 4500 metres, are due to the 

 influence of Mediterranean water. This assumption is 

 strengthened by sections published by WOst [1928, Pis. 

 XXXIIl and XXXlVj, showing, for instance, that at depths 

 below 4000 metres a maximum of salinity appears in 

 about 15 — 35° N. in the central part of the eastern North 

 Atlantic. 



In this connection it may also be noted that the 

 temperature at the "Michael Sars" Stat. 10 A, 4500 metres, 

 is relatively high. This station was worked in an area 

 north of Cape Finisterre where water from the Mediter- 



