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



61 



eiices from one locality to another. Even if we could 

 restrict our examination to a characteristic current, the 

 results might be rather doubtful, because the velocities 

 may differ greatly in horizontal and vertical direction. 

 Besides the purely thermal ("physical") variations we may 

 have changes in the distribution and intensity of the cur- 

 rents ("dynamic" variations), of such a nature that the 

 actual mean temperature within an area may be higher 

 or lower than the normal, even if the "anomalies of 

 temperature", found by means of the salinities, do not 

 indicate it. In consequense of all these complications, 

 the unravelling of the annual variations of temperature 

 in the sea is at present very difficult. The material we 

 possess may, however, give some indications. 



hi the North Atlantic E. of 20° W. the velocity of 

 the currents may be very considerable at about 100 metres 

 below the surface, but probably in limited regions only. 

 In our area "B" (Fig. 11) the velocity on the whole seems 

 to be relatively small at such moderate depths, so the 

 water is not carried far in the course of several weeks or 

 months. A rapid motion in vortices is of no consequence 

 in this connection. Accordingly we may compare the 

 "anomalies of temperature" for moderate depths in spring 

 with the temperature of the surface in February. A similar 

 comparison may to some extent be carried out for "C". 

 From area "A" the material is too small. 



A comparison of Fig. 20 with Figs. 15 and 16 may 

 give us some hints, but only in respect of the years 1905, 

 1906, 1909 and 1910. We have no data from other 

 years for this purpose. 



From 1905 wt have 3 stations within area "B" in 

 June, at about 51^ .50° and 48° N. (the latter station at 

 about 8° W.) We have observations from 4 other expe- 

 ditions and years in this area in June so that the average 

 variation of temperature during this month is fairly well 

 established (Fig. 15). The stations from 1905 seem to 

 indicate that the temperatures at 50 and 100 metres below 

 the surface were above the average for the times of 

 observation. This agrees with the annual variations exhi- 

 bited by the curves in Fig. 20 (the second and third 

 from the top). 



In 1906 we have some stations taken by the "Thor" 

 expedition in the northern part of our area "B" during 

 June and August-September. The observations from June 

 show normal temperatures at 50 and 100 metres, in accor- 

 dance with the corresponding curve (the second from 

 the top) in Fig. 20. 



In 1909 two stations taken from the "Thor" in the 

 sea S. of Portugal (area "C") at the end of February 

 show relatively low temperatures at all depths between 

 the surface and 100 metres, which corresponds well with 

 the low temperature at the surface in the nearest field to 



the NW (the lowest curve in Fig. 20). Two stations in 

 the Bay of Biscay ("B") at 45° 37' and Al" V N. in 

 March (Fig. 15) seem to accord well with the normal 

 conditions exhibited by curve no. 3 in Fig. 20. 



The "Michael Sars" observations from 1910 in area 

 "B" in April and July seem to correspond to normal 

 temperatures, as do also the surface observations in Fe- 

 bruary. Some "Michael Sars" and "Thor" stations in 

 the sea between Portugal, Spain and Morocco (area "C") 

 indicate normal temperatures in May and June 1910 at 

 50 and 100 metres, while the surface temperature in the 

 sea W. of Portugal was relatively high in February. (I 

 have no material at hand to find the mean surface tem- 

 perature and its relation to the normal temperature in 

 this region in March). 



On the whole, there seem to be fairly good indica- 

 tions of a direct agreement between the aiuiual variations 

 of the surface temperature towards the end of the winter 

 and the temperature for a considerable time (several 

 months) afterwards at 50 and 100 metres, the transport 

 of the water from one field to another being taken into 

 consideration. 



Assuming that our graphs in Figs. 15 and 16 may 

 be utilized for tracing further indications of annual varia- 

 tions in the upper water-strata, we find that spring and 

 early summer may be characterized as noimal in 1911 

 in area "B"; we have no observations of this kind from 

 "C" in that year. The temperature was nearly normal 

 in 1914 in both the areas "B" and "C", and in 1922 in 

 "B". In the latter year the temperature was probably 

 slightly below the normal in area "C", where it seems 

 to have been relatively high in 1924 (March and May). 

 The conditions in 1925 are uncertain. 



Fig. 21 illustrates the vertical distribution of tempe- 

 rature, salinity and density at the "Michael Sars" station 

 89 in 1910 and the "Armauer Hansen" station 58 in 1914. 

 The stations had nearly the same position. The dates 

 correspond to the numbers 201 and 191 in the chart, 

 Fig. 11. In the same way the two next figures illustrate 

 the conditions at a "Michael Sars" station and another 

 taken quite near it but in a different year. The years 

 (and dates) of the observations represented in Fig. 22 

 are 1910 (202) and 1922 (177); and in Fig. 23 they are 

 1910 (204) and 1906 (246). The differences in tempera- 

 ture and salinity between one of the alien stations and 

 the corresponding "Michael Sars" station have been com- 

 puted for various depths, and are illustrated in the dia- 

 grams inserted to the right in the figures. 



Leaving the uppermost water-strata out of account 

 we see from Figs. 21—23 that the temperature at the 

 stations considered was, on the whole, lower in 1910 

 than in the other years. At the same time we find differ- 



