532 



Currents in a Strait 



measurements have been made by Idrac (1928) on the vessel "Pourquoi-pas" in 

 March 1927 to the south of Tarifa. These gave the following values (depth 600 m). 



The current boundary surface very probably lies at 1 50 m v/hich is about the same 

 depth as that found above. This can be compared with more recent investigations by 

 Menendez (1956). 



1/ cm/^ec 1/, cm/sec 



O 20 , 40 60 80 10 20^ 40 60 



200 



250 



300 



350 



Fig. 246. Vertical current distribution in the Straits of Gibraltar and Bab el Mandeb; 

 1 1 1 , according to the observations; • — • , according to the theory. 



Conditions in the Strait of Bab el Mandeb are essentially similar. The temperature 

 and salinity distribution are given in Pt. I, p. 182, Fig. 84. Rather early current 

 measurements have been made by Gedge (1898) in the Perim Strait at the surface and 

 at 192 m, and they indicate a strong inflow with a velocity of at least 2-2-75 nautical 

 miles per hour at the surface. The current intensity decreased rapidly with depth and 

 showed a reversal in direction at 130-140 m; the speed of the lower current was 

 variable between 1 and 3 nautical miles per hour. The research vessel "Arimondi" 

 in 1924 made a 15-day measurement at almost the same place and a harmonic analysis 

 of this data was made by Vercelli (1925). The results for the basic current are given 

 in Table 143. 



Table 143. Velocities of the basic current in the Strait of Bab el Mandeb 



{March 1924) sea bottom at 175 m; depth of boundary surface at 100 m 



(+, inflow from the Gulf of Aden; — , outflow from the Red Sea) 



