Southern California Fog Disappearance: Global Warming, ENSO or Selective Statistics?

Authors: Steve LaDochy*, California State University Los Angeles, Michael Witiw, Certified Consulting Meteorologist
Topics: Climatology and Meteorology, Coastal and Marine, Global Change
Keywords: fog climatology, Pacific climatic indices, climate trends
Session Type: Interactive Short Paper
Day: 4/11/2018
Start / End Time: 1:20 PM / 3:00 PM
Room: Bayside B, Sheraton, 4th Floor
Presentation File: No File Uploaded


Continuous fog data from the 1940s show a rapid decline in coastal fog frequencies in southern California. Earlier studies show that these declines are related to urban heat island, ENSO and PDO cycles, particulate air pollution levels, sea surface temperatures and upwelling values. Studies in recent decades have shown both increases and decreases in California fog occurrences depending on what years (and seasons) were chosen. For instance, one study showed increasing sea breezes and summer fog in the SF Bay area from 1970-2005. This period corresponded to a switch from the mostly warm phase of PDO to the cool phase. Using annual fog data over a longer period, the reverse was found, with decreasing coastal fog again. While the overall trend of declining fog along the California coast has been well documented, the oceanic climate cycles, particularly ENSO and PDO can explain much of inter-annual variability.

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