JOHNSON and McLAIN: TELECONNECTIONS BETWEEN OCEANS 



This paper extends the findings of several of the 

 authors mentioned above by describing the 

 development of large-scale sea-surface tempera- 

 ture anomalies in the winter of 1957-58 in the Gulf 

 of Mexico and off the U.S. eastern seaboard 

 and suggests that these anomalies are associated 

 with ridges and troughs in the upper air circula- 

 tion. These, in turn, are associated with air-sea 

 interactions in the Pacific. It further describes 

 conditions in other winters where similar situa- 

 tions developed and suggests that changes in 

 abundance and distribution of some fish popula- 

 tions both in the Pacific and Atlantic may be 

 caused by events of this nature. 



DATA SOURCES 



Data used in heat budget calculations and in the 

 description of sea-surface temperatures and 

 anomalies were obtained from Tape Data Family 

 11 obtained by Fleet Numerical Weather Central 

 and the Navy Oceanographic Oflfice from the Na- 

 tional Climatic Center, Asheville, N.C. This file 

 contains merchant ship weather reports, some of 

 which date back to 1854. Computer programs were 

 developed to compute monthly averages by year of 

 sea-surface temperature and heat exchange by 5° 

 blocks. 



Numerous studies have been made to determine 

 the accuracy of sea-surface temperatures reported 

 by merchant vessels in their weather reports. Saur 

 (1963) found that in the Pacific the average injec- 

 tion temperature bias from that of a bucket 

 temperature taken at the surface was about 

 -l-1.2°F, and Franceschini (1955) noted similar 

 results in the Gulf of Mexico. The latter suggested, 

 however, that commercial vessel reports could be 

 used for practical purposes such as meteorological 

 and oceanographic research and for forecasting 

 air mass modification over the Gulf. Because un- 

 certainties remain concerning the relation 

 between temperature at the sea surface and that 

 at the injection intake depth of merchant vessels, 

 no attempt was made in this study to apply a 

 correction. 



OBSERVATIONAL EVIDENCE OF 

 ANOMALOUS AIR-SEA EVENTS 



The Anomalous Winter of 1957-58 



Charts of the height of the 700-mb (millibar) 

 pressure surface (on the average about 10,000 feet 



above the surface of the earth in temperate lati- 

 tudes) are particularly significant in air-sea 

 interaction studies because the mass circulation of 

 the atmosphere can be inferred from them includ- 

 ing areas of cyclogenesis and movement of storms. 

 Furthermore, mean 700-mb heights over the ocean 

 are highly correlated with 700-mb temperatures, 

 which in turn are measures of the vertical stability 

 in the atmosphere over the ocean. For example, 

 low temperatures at the 700-mb level, associated 

 with negative 700-mb height anomalies, indicate 

 instability in the atmosphere and loss of heat from 

 the ocean through convective processes in the at- 

 mosphere. 



O'Connor (1958) reported that the heights of the 

 700-mb surfaces during the winter of 1957-58 were 

 very unusual. He reported the following three ab- 

 normalities in the 700-mb circulation in January 

 1958 (Figure 1) which persisted into February: 



1. A trough in the east-central Pacific with 

 700-mb heights 550 feet below normal 700 

 miles south of Kodiak, Alaska, 



2. A block in the Davis Straight where the 

 700-mb heights averaged 520 feet above 

 normal and, 



3. A trough in the southeastern United States 

 (having 700-mb heights about 300 feet 

 below normal) accompanied by strong 

 northerly surface flow. 



The trough along the eastern seaboard is par- 

 ticularly important. It suggests greater than nor- 

 mal penetration of cold continental air masses 

 over the southeastern United States and adjacent 

 waters. Indeed, the winter of 1957-58 will be 

 remembered as one of the most severe of the cen- 

 tury. Data taken at National Weather Service 

 stations in the southeastern United States show 

 slightly higher than normal air temperatures in 

 November 1957 (Table 1). A small negative 

 anomaly developed in December which increased 

 substantially in January 1958 and reached a 

 maximum in February. Monthly deviations of air 

 temperature ranged up to 5.8°C below normal at 

 stations along the northeast coast of the Gulf of 

 Mexico. 



Large negative sea-surface temperature 

 anomalies also prevailed in February 1958 and 

 were greatest in the northeastern Gulf in the same 

 general area where shore station air temperature 

 anomalies were highest (Figure 2). Stearns' (1964, 



307 



