THERMAL PATTERNS OF PACIFIC SOUTH AMERICA ASSOCIATED WITH EL NIÑTO/SOUTHERN OSCILLATION

This study quantifies the magnitude of temperature anomalies associated with extremes of the Southern Oscillation (SO) for 12 long‐record stations and five shorter‐record stations along the west coast of South America. Analysis of t‐tests indicates that nine stations north of 35°S have a strong inverse relationship between their mean annual temperature and the sign of the Tahiti–Darwin Southern Oscillation Index (SOI). Significant inverse relationships are determined between the phase of the Southern Oscillation and (i) summer temperatures (five stations), (ii) autumn temperatures (eight stations), (iii) winter temperatures (eight stations), and (iv) spring temperatures (four stations) for the region north of 35°S. In particular, the northern mid‐latitude stations (18°S–33°S) along the‐west coast of South America show a pronounced seasonal pattern in temperature differences between extremes in the SO. The summer temperature increases associated with negative SOI values may be due to warm air advection from the equatorial regions. The increase in winter temperatures may be caused by warm air advection from the mid‐latitudes associated with greater zonal flow caused by weakening of the South Pacific subtropical high. Stations south of 35°S display little temperature contrast between extremes of the SO.