The Atmosphere–Ocean Influence

Abstract

The connection between events in the atmosphere and the ocean is well known. While not fully understood, California weather is related to several of these ocean–atmosphere interactions. The most widely known of these interactions is the El Niño Southern Oscillation (ENSO) where water temperatures in the central and eastern tropical Pacific Ocean are either above normal (El Niño) or below normal (La Niña). ENSO events, on average, affect the southern part of California with the most intensity. During El Niño years, precipitation tends to be above normal and during La Niña periods below normal in southern California. However, there are many exceptions to this rule as the 2022–23 La Niña water year was exceptionally wet. Another ocean–atmosphere oscillation that affects California is the Pacific Decadal Oscillation (PDO). The PDO is a long-lasting oscillation which transitions from a warm phase (warmer than normal sea surface temperatures off the west coast of North America) to a cold phase (colder than normal temperatures off the west coast). The PDO affects the weather of California as well as the intensities of ENSO events. The chapter explores these along with other ocean–atmosphere interactions that likely have some effect on California’s weather.

There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy.—William Shakespeare (Hamlet)