Hydrographical Observations from the Danmark Expedition. 369 



In the series LX IV A (falling water) the salinity and tempera- 

 ture changed in the same way in all three depths, the lowest values 

 occurring ca. 1 14 hours after low water. 



In the series LXIV В (rising water) the salinity at a depth of 75 

 m. is seen to have increased, approaching to the salinity at 100 m. 

 which has remained nearly constant as also the temperature, whilst 

 the temperature at 75 m. has decreased. 



Some time after high water the water in 100 m. is pressed up in 

 a wave and runs out immediately afterwards, whilst the water in 

 75 m. has already previously begun to run outwards. 



Changes also occurred in the temperature and salinity at other 

 depths than those mentioned, but as in the upper layers (0—75 m.) 

 the temperature and salinity were nearly uniform beforehand, the 

 changes could here only be inconsiderable. 



Discussion. 



On the basis of the available material it is not possible to dis- 

 cuss in too great detail what occurred, when the tidal \\'ауе forced its 

 way into the mouth of Øresund; for this we ought to have a series 

 of simultaneous observations at different depths and from different 

 stations. 



The movement of the water-masses, however, has evidently given 

 rise to two kinds of variations in the temperature and salinity, 



1. those due to the periodic movement in from the sea up over 

 the barrier and out again, and 



2. those due to the mixing which occurred over the barrier and 

 which led to actual changes in the water-masses there, a nearly ho- 

 mogenous mixed layer being formed. 



1. The first-mentioned variations were observed in the layer 

 75 — 150 m. depth and could attain to such considerable values, that 

 to compare observations from these depths we should require to refer 

 them to a definite point of time. The material of observations is, 

 however, not large enough to permit of a correction table being drawn 

 up; it may be said quite in general, that temperature and salinity 

 increased with rising water and decreased with falling water. 



2. As mentioned, we may imagine the condition to be, that the 

 water-masses below the depth of the barrier (ca. 50 — 75 m.) ran in 

 parallel to the rising sea-bottom, whilst the water-masses above the 

 depth of the barrier ran nearly horizontally. Consequently, there 

 was a tendency to the formation of a homogenous mixed layer on 

 the barrier, and as the salinity and temperature in the uppermost 

 75 m. in Øresund were as a rule lower than in the sea below this 

 depth, there resulted an inflow of heat and chlorides from the deeper 



xLi. 24 



