Mean depth of upper level of the thermocline in summer (1902-1954) 
Mean depth of lower level of the thermocline in summer (1902-1954) 
Mean strength (lower minus upper level) of the thermocline in summer (1902-1954) 
Mean intensity (upper minus lower level) of the thermocline in summer (1902-1954) 
□ 
K 
8 
6 
5 
4 
3 
2 
— 
1