40 



determined once. On Figure 21 is shown the result of the dynamic 

 calculations, or the relative topography (1500 decibars). The 

 dynamic height contours are drawn for each 2 centimeters. 



The surface-temperature maps, Figures 23 to 27, have been con- 

 structed in the same way as in previous years and the isotherms have 

 been drawn for 32°, 37°, 42°, 48°, 54°, 60°, 66°, and 70° F. in order 

 to be able to compare them with maps from earlier years. The 

 number of temperature reports from ships is smaller this year than 

 usual. One reason for this is probably that many ships were not 

 interested in taking surface temperatures this year because of the lack 

 of ice. Another reason is that the General Greene much of the season 

 stayed farther north than is usual for the ice-patrol cutters. This 



51 /v 



'Aff 



5iw tfur 



FiouiiE 21.— Dynamic topography along the line of stations occupied from April 1 to 4, 1931 



prevented many ships on the United States-Europe tracks from being 

 able to hear our radio. 



The lirst temperature map, Figure 23, for the period April 10 to 

 22, shows some interesting features. The water is in general warmer 

 than at the same time in other years. In a location about latitude 

 43° 30' N. longitudes 53° to 55° W. temperatures between 50° and 

 60° F. are reported, which are a great deal higher than usual. Fur- 

 thermore, there is a distinct invasion of warm water on the other side 

 of the Banks, toward the eastern slope. However, the number of 

 temperature reports is small, and, in order to give the right impression 

 of the situation, all temperatures reported have been shown in figures 

 on the map. 



Figure 24 is the temperature map for the period May 2 to 16, 

 1931. The water is a little warmer than usual, which will easily be 

 seen by comparing with maps from other years. 



