Long-term trends and changes in the hydrography of the Faroe-Shetland Channel region 493 



the present century, little if any specific notice has been taken of the relatively infre- 

 quent occurrence of salinity values below 34-90%o. There is, however, clear evidence 

 in the tabulated observations of a frequency concentration of such low salinity 

 records, from 34-82°/,,^ to 34-887oo with occasional instances of 34-76 ^/, to 34-79 /_, 

 in the years between 1907 and 1910 inclusive, such as occurred again towards the 

 end of the fifth and the beginning of the sixth decades. 



TEMPERATURE AND SALINITY 



HORIZONTAL SCALE = I 1,000,000 

 VERTICAL SCALE = I 5,000 



NOLSO). FAROE -FLUCCA, SHETLAND. 



F R S "SCOTIA" 

 12-13 SEPTEMBER, ("J^S 



Fig. 6 



Apart from a singular, isolated, 34-87 '/^o saUnity record in July 1934, no Faroe- 

 Shetland deep water sahnity value below 34-90°/^^ was encountered in the years be- 

 tween 1931 and 1939 inclusive. Similar isolated results were again evident in July 

 and August 1946, but by the month of June 1947 (Fig. 4) almost one-half of the deep 

 water mass underlying the oceanic water-mass was of the relatively low sahnity of 

 34-877oo to 34-897oo. and had a higher minimum temperature than the neighbouring 

 deep Norwegian Sea water-mass. It seems clear from Helland-Hansen and Nansen 

 (1909) that this low sahnity (34-867oo-34-89''/oo) intrusion into, and sometimes dis- 

 placement of, the deep Norwegian Sea water-mass of the Faroe-Shetland Channel, 



