Storm surge along the Pacific coast of North America

Abstract

Storm surge is an important factor that contributes to coastal flooding and erosion. Storm surge magnitude along eastern North Pacific coasts results primarily from low sea level pressure (SLP). Thus, coastal regions where high surge occurs identify the dominant locations where intense storms make landfall, controlled by storm track across the North Pacific. Here storm surge variability along the Pacific coast of North America is characterized by positive nontide residuals at a network of tide gauge stations from southern California to Alaska. The magnitudes of mean and extreme storm surge generally increase from south to north, with typically high amplitude surge north of Cape Mendocino and lower surge to the south. Correlation of mode 1 nontide principal component (PC1) during winter months (December–February) with anomalous SLP over the northeast Pacific indicates that the dominant storm landfall region is along the Cascadia/British Columbia coast. Although empirical orthogonal function spatial patterns show substantial interannual variability, similar correlation patterns of nontide PC1 over the 1948–1975 and 1983–2014 epochs with anomalous SLP suggest that, when considering decadal‐scale time periods, storm surge and associated tracks have generally not changed appreciably since 1948. Nontide PC1 is well correlated with PC1 of both anomalous SLP and modeled wave height near the tide gauge stations, reflecting the interrelationship between storms, surge, and waves. Weaker surge south of Cape Mendocino during the 2015–2016 El Niño compared with 1982–1983 may result from changes in Hadley circulation. Importantly from a coastal impacts perspective, extreme storm surge events are often accompanied by high waves.

Southern California Coastal Response to the 2015–2016 El Niño

“…This possibly prevented the classical teleconnections that deliver elevated rainfall to California. Bromirski et al () suggest that changes in the Hadley circulation possibly limited storm surge during the 2015–2016 event compared to other El Niño events. These characteristics make the 2015–2016 El Niño event unusual compared with earlier recorded strong canonical El Niño events where storm tracks are shifted south, creating a more westerly wave approach, generally greater wave exposure, and increased rainfall for Southern California.…”

“…Barnard et al (2015) found the contrasting coastal behavior observed on opposite sides of the Pacific most closely follows ENSO compared to other climate indices. However, El Niño characteristics can vary considerably (Capotondi et al, 2015) and associated wave energy levels and storm surges differ widely (Bromirski et al, 2005(Bromirski et al, , 2017. Kao and Yu (2009) broadly categorize El Niño events by the location of the major sea surface warming anomaly: Eastern Pacific (canonical; e.g., 1997-1998) and central Pacific (e.g., 2009Pacific (e.g., -2010.…”

“…This possibly prevented the classical teleconnections that deliver elevated rainfall to California. Bromirski et al (2017) Journal of Geophysical Research: Earth Surface shifted south, creating a more westerly wave approach, generally greater wave exposure, and increased rainfall for Southern California. Adams et al (2008) found that Southern California deepwater waves during previous El Niños coinciding with a warm phase PDO are larger, have longer periods, and are shifted more westerly compared to a cool phase PDO.…”

High‐frequency greenhouse gas flux measurement system detects winter storm surge effects on salt marsh

“…We calculated the percent change in sea level between 2010 and 2020 to provide the 2015 starting value corresponding to the gas flux data Bromirski, Flick, and Miller (2017). The hourly average environmental data were calculated as the average of only those values associated with the timing of the chamber measurements.…”

“…We used the averaged values achieved from our selected time periods to estimate the C and N flux for the winter months (November-March) with increasing frequencies of surge determined by proxy as percent increases corresponding to global mean sea level rise scenarios from year 2020 to 2100 of 0.5 ± 0.02 m (NOAA Intermediate-Low) and of 1.5 ± 0.05 m (NOAA Intermediate-High;Sweet et al, 2017). We calculated the percent change in sea level between 2010 and 2020 to provide the 2015 starting value corresponding to the gas flux data Bromirski, Flick, and Miller (2017). reported that Seattle had 66 extreme surge events (lasting at least 6 hr) over 29 winter seasons(December-February 1980-2008.…”