Climate variability and large storm surge on the Pacific coast of the United States

We analyze daily mean sea-level height measurements for one hundred years from three National Oceanographic and Atmospheric Administration tide stations on the U.S. Pacific coast. The largest winter storm surges have increased in frequency since early in this century. Linear and negative binomial regression models imply the frequencies of the largest storm surges have increased roughly 150% in San Diego, while San Francisco shows a somewhat less significant increase of 40%. There is no statistically significant change in Seattle. Increased storm surge frequency in San Diego and San Francisco appears to be positively associated with a greater frequency of intense El Nino events in recent decades. With the possible exception of the very strong El Nino winters of 1983 and 1998, the incidence of El Niños appears to be negatively correlated with that of large storm surges in Seattle.

We use hourly sea level data for San Francisco from 1854 to 2000 to estimate the joint probability of extremes in the tide, mean sea level and storm surge for a range of climate scenarios. We assess the probability under each scenario of exceeding critical thresholds for coastal infrastructure in San Francisco and the Sacramento River Delta in the next 100 years.