CTD

Steve Pengilley with a CTD.  

The waves crashing on the shore felt like the rumbling from the footsteps of giants walking across the Pacific on March 1, 1983. People in Avila Beach felt their homes shake with each set of gigantic waves that crashed on their beach with fearsome power.

In 1983 one of the strongest El Niño events in California history was in full swing. NOAA uses a region called Niño 3.4, an area in the central equatorial region of the Pacific Ocean, as the standard for classifying El Niño (warmer-than-normal sea-surface temperatures (SST).

The SSTs in Niño 3.4 were over four degrees Fahrenheit above normal over a three-month period during the winter of 1983. These very warm SST produced a greater amount of evaporation and convection, which allowed the jet stream to take a more southerly route. This condition caused winter storms to come in from a west-southwesterly direction versus the more typical northwesterly direction of storms from the Gulf of Alaska.

Consequently, the ocean waves that these storms generated approached our rugged coastline directly from the southwest as opposed to the normal northwesterly direction. You see, as northwesterly waves bend around the Point San Luis they greatly diminish in height by the time they turn into Port San Luis. With the southwesterly waves there was no loss of wave energy due to refraction. In fact, the topography of the ocean floor near Avila Beach amplified the wave heights.

It was estimated that on March 1, 1983, a significant swell height (the average height of the waves in the top third of the wave record) reached 27 feet with a 19-second period.

This swell event destroyed the 2,700-foot-long wooden Unocal Pier in Port San Luis. The pier was built in 1914 to carry oil from the world’s biggest oil pipeline at the time.

However, renewal can come from destruction. The pier was replaced with a stronger steel and concrete structure in 1984 that extends about a half-mile into San Luis Bay. In 2001 Unocal, now Chevron, donated the pier to the college of science and mathematics at Cal Poly.

Today, Cal Poly’s Center for Coastal Marine Sciences at the end of the pier has become one of the premier marine science and research facilities along the entire West Coast. It’s unique.

Cal Poly’s “Learn by Doing” educational philosophy is employed by students from both Cal Poly and Cuesta College. Professors, technicians and students conduct research into local marine life and oceanic conditions. Since its donation to the university, the pier has been used by about 1,500 students each year for classes or research activities.

One of tools that Cal Poly and Cuesta College faculty and students use to study the ocean is a Sea-Bird Conductivity-Temperature-Depth (CTD) profiler. This 50-pound, 3-foot-long instrument can be cast down thousands of feet into the ocean, collating vast amounts information from temperature and pressure to chemistry and other types of oceanographic information. This one of the instruments used to measure the strength of El Nino events.

The Cal Poly pier will be opened to the public from 9 a.m. to 2 p.m. Saturday, Nov. 26. Cal Poly professors and students will be on hand to explain their ongoing research into local marine life, sustaining local fisheries and mapping ocean currents on the Central Coast. There will also be Interactive displays and touch-tanks chuck-full of live marine creatures. Poly Pier is a little more than a half-mile long (1.2 miles round trip), and displays will be located at the end of the pier. Safety rules require that everyone admitted to the pier wear closed-toe walking shoes (no flip-flops or high heels).

John Lindsey is Pacific Gas and Electric Co.’s Diablo Canyon Power Plant marine meteorologist and a media relations representative. Email him at pgeweather@pge.com or follow him on Twitter @PGE_John.

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