JOHNSON and McLAIN: TELECONNECTIONS BETWEEN OCEANS 



^0.8 0.9 

 ^ ciJ + +'^ + + + 

 ==2^ 0.3 0.3 0.21.0 1.4 



- , . - . _ + 

 1 .4'0.8 0.4 0.40.1 0.4 



2.01.0 0.4 0.20.0 0.1 

 ,61.7 1.2 2.,51.51.2 0.9i 0.6P.6!d.4 



-- - -i. __4. + 



OVIO.6 0.4-2;51,00.6 0,2 0,30.3 0,2 



I  ,■■ ,^ - -f + _i+ + + + 



0.6 0.10.10.1 0.4 0.50.1 0.6 

 + + + + + + + 



0.41.01 .3 .7 0.60.9 0.3 



T '■'■■■' I " ■- f   " 



110° 100* 90° 



80' 



70 



60 



50 



Figure 2.-Sea-surface temperature anomalies (°C) Gulf of 

 Mexico and western Atlantic Ocean, February 1958. Shaded area 

 colder than 20-yr (1948-67) mean. 



1965) analysis of sea temperatures at coastal sta- 

 tions confirm the large winter sea temperature 

 anomaly in coastal areas of southeastern United 

 States. The extent of the anomaly was large, in- 

 deed, extending from below the Yucatan Straits 

 northward throughout the Gulf to lat. 40°N off the 

 eastern seaboard and to over a thousand miles 

 offshore. 



Important in this study is the anomalous change 

 in sea temperatures in the winter of 1957-58 

 (Figure 3). The change from November to 

 February shows that much higher than average 

 cooling occurred over a broad expanse of the ocean 

 during this winter. For example, the 1948-67 

 average change in sea-surface temperature in 

 winter (November average - February average) is 



/rr^^ 



(^ 1 .n.6 

 <=C7 - -'^+ + + 



cc^ 0.6O.9 0.9 1.S1.6 



- / - . - + + 

 2.61 .50.1 1.0 0.60.6 



2.20.50.3 0.1 0.10.2 



1.3 1.0:1.4 2.91.50.90.5 0.30.50.5 

 - - : - + + 



on, v. 2-0, 7, 2.50.8 0.60.3 0.1 0^30^3 



0.9 0.40.2 0.00.1 0.5 0.21.0 

 1+ + + + + + + 



0.10.6 1.00.3 0.4 0.70.1 



I o I o 



100 90 



80 



Vo° 



60 50 



Figure 3.— Anomalous sea-surface temperature change (°C) 

 November 1957 to February 1958. Shaded area indicates 

 anomalous cooling. 



about -2.7°C in the area lat. 25° to 30°N, long. 80° 

 to 90°W. In the winter of 1957-58, however, the 

 change in this area was -4.7°C-an anomalous 

 change of -2.0°C. 



Cause of Sea-Surface Temperature 

 Change in the Winter of 1957-58 



A variety of processes can cause changes in 

 sea-surface temperatures. Some of these are 

 horizontal and vertical advection and heat 

 exchange at the air-sea interface. 



In studies in the eastern Pacific Ocean, Clark 

 (1972) has found that horizontal advective heat 

 transfer processes in winter and spring have a 

 greater effect in causing anomalous sea-surface 

 temperature change than nonadvective processes. 

 The latter have a greater effect in summer and 

 fall. The area that he studied, however, was not 

 subject to influence of a large continental land 

 mass interacting with atmospheric circulation up- 

 stream from where heat exchange processes were 

 calculated. 



Horizontal advection into the Gulf of Mexico is 

 mainly through the Yucatan Straits. Sea-surface 

 temperature anomalies in these Straits ranged 

 from -0.2°C to -H 0.4°C (Table 2) for a year preced- 

 ing the maximum development in February 1958 

 of the severe cold anomalies in the Gulf of Mexico 

 and along the eastern seaboard. This clearly sug- 

 gests that horizontal advection was not the cause 

 of the development of the cold anomalies. 



Klein (1958) noted that the intensification of 

 blocking in the 700-mb circulation in the north- 

 west Atlantic in the winter of 1957-58 was as- 

 sociated with frequent outbreaks of cold air in the 



Table 2. -Sea-surface temperatures and anomalies (°C) in 1° 

 square (long. 85° to 86°W and lat. 21° to 22°N) in Yucatan 

 Straits. 



Date 



Sea temperature 

 °C 



Anomaly 



°C 



-0.2 



+0.3 



-0.1 



+0.1 



+0.2 



0.0 



+0.1 



0.0 



-0.1 



-0.2 



0.0 



+0.4 



-0.2 

 -0.7 



309 



