Abstract: Possible Relations Between North Pacific Water Temperatures and Anomalous Runoff in Circum-Pacific Region

Robert A. Clark

Numerous recent studies have indicated possible relations between North Pacific surface-water temperatures and weather patterns on the Pacific Coast of the United States, Canada, and Mexico. Though it is agreed generally that sea-surface temperatures are influenced by the atmosphere, which is affected in return by the seawater temperatures, most scientists do not agree on which is the cause and which is the effect.

Variations in seasonal weather patterns have a profound effect on the hydrologic regime of the Pacific Coast. For example, during the winter of 1976-77 a high-pressure ridge that dominated the west coast, deviated most cyclonic systems far to the north, and produced much warmer and dryer conditions than normal on the West Coast and very cold conditions in the eastern United States. Alaska experienced one of the mildest and wettest winters on record. Above-normal sea-surface temperatures were observed in the eastern equatorial Pacific and the central North Pacific had cooler than normal temperatures. This condition has been observed to favor intensification of a deep trough over the central Pacific Ocean and to strengthen a high-pressure ridge on the west coast of North America.

Anomalies of sea-surface temperature in the eastern North Pacific are associated with statistically significant effects on sea-level pressure in the Pacific coastal region. These departures of sea-level pressure from normal, in turn, appear to be highly correlative with anomalous precipitation. Anomalous precipitation is, of course, associated with anomalous runoff.

The predictive skill associated with knowledge concerning sea-surface temperatures is still more qualitative than quantitative. Meteorologic models that incorporate sea-surface temperatures for the prediction of sea-level pressure have yielded virtually identical results for a period of about a week, whether computed with climatologic or observed sea-surface temperature fields. The spatial resolution of these models, however, may be too large to account for some of the smaller scale temperature anomalies. In addition, these models may be too insensitive to surface fluxes and their anomalies. Recent work at the National Meteorological Center has indicated increased accuracy in atmospheric predictability with models using higher spatial resolution.

AAPG Search and Discovery Article #90962©1978 AAPG 2nd Circum-Pacific Energy and Minerals Resource Conference, Honolulu, Hawaii