El Niño's West Coast Impact
NOAA scientists track ocean indicators for El Niño's arrival on West Coast
Introduction To El Niño's Impact
Scientists at the National Oceanic and Atmospheric Administration (NOAA) are closely monitoring ocean indicators for signs of El Niño's arrival on the West Coast. Despite the recent marine heat wave that has warmed the ocean off Southern and Central California, the region is still awaiting the full impacts of what could be a very strong El Niño event. The declaration of El Niño's development in June was based on ocean temperatures in the tropical Pacific Ocean near the equator, which have already risen more than 2°C above normal.
Understanding Ocean Conditions
During an El Niño event, winds that typically blow westward along the equator weaken and periodically reverse, setting off oceanic Kelvin waves that travel east along the equator. These waves then travel north as coastal trapped waves along the North American coast, creating a link between the tropics and the United States known as an oceanic teleconnection. This phenomenon produces relatively small changes in sea level, approximately 15 cm or 6 inches, that are measurable at tide gauges along the coast and from satellites. 
Tracking Kelvin Waves And Water Temperature
Kelvin waves originating along the equator this spring and summer first reached California in May-June. However, their impacts on the West Coast will likely be minor compared with those this fall and winter. As these Kelvin waves move north along the coast, they deepen the thermocline, an underwater boundary at which temperatures drop rapidly at greater depths. Additionally, an atmospheric teleconnection allows El Niño conditions in the tropics to modify atmospheric pressure patterns over the North Pacific, weakening or reversing winds that normally drive upwelling of cold, nutrient-rich water along the coast.
Biological Indicators And Shifting Distribution Of Fish
NOAA Fisheries scientists are tracking changes in ocean conditions and marine life that typically signal the arrival of El Niño's influence along the West Coast. One key biological indicator is the shifting distribution of fish. Migratory fish that favor warm waters are known to increase in abundance off the West Coast during El Niño events. Scientists are monitoring the distribution of these fish species, as well as other biological indicators, to better understand the impacts of El Niño on the region's ecosystems.
Real-World Implications And Future Outlook
The arrival of El Niño on the West Coast is expected to have significant impacts on the region's ecosystems and fisheries. Unusually high temperatures and changes in ocean conditions may affect the distribution and abundance of marine species, with potential consequences for commercial and recreational fisheries. NOAA scientists will continue to monitor ocean indicators and biological responses to El Niño, providing critical information for resource managers and stakeholders to prepare for and respond to the event.
Sources
This is an original synthesis by Qivorane based on reporting from the outlets below.