El Nino And Monterey Bay Geek Page

How the advent of El Nino (which now looks like less of a sure thing) stirred up warming Kelvin waves and quelled our usual summer winds—and is making trouble for Monterey Bay.

by L. Clark Tate

Aug. 13, 2014—An El Nino kicks off when the trade winds that normally rip from Peru to Indonesia, trapping a stack of equatorial water in the western Pacific in the process, slack off, allowing massive sun-warmed waves of energy known as Kelvin waves to slosh back towards South America. When these hit the coast of Peru, they disperse along the coast, moving north towards our very own Monterey Bay.

Kelvin waves don’t move water around like currents do. They heat waters by deepening the thermocline, or the temperature gradient between the warm surface waters and the deep, dark and very chilly ocean floor. “Deepening the thermocline” means that it thickens the layer of surface water, creating a warmwater cap.

Francisco Chavez, a senior scientist at the Monterey Bay Aquarium Research Institute, agrees that Kelvin waves are a possible partial culprit in this summer’s warm-water phenomenon in Monterey Bay. But mostly, he blames the wind. Or lack thereof. National Weather Service Forecaster Steve Anderson corroborates. Normally, the scientists explain, there is a strong high-pressure system offshore to the north, slinging winds outward and spinning counterclockwise. That sends northwestern gusts ripping right at Monterey Bay. Right now, though, the high-pressure system is out of place, giving a low-pressure system enough room to settle in and pull air up from the south. Chavez believes these weather shifts are also linked to early El Nino action. According to Anderson, the weather just isn’t moving around like usual, and that’s allowing systems to languish.

But while early reports were calling for an epic El Nino year, and we are likely experiencing early effects, it looks like its power is waning (read more at the Santa Cruz Sentinel). William Patzert, an ocean circulation expert at NASA’s Jet Propulsion Laboratory, believes that the cool waters of a negative Pacific Decadal Oscillation shut it down, along with potential drought-relieving rains. In fact, Patzert links negative PDO’s to California droughts in general (1945 to 1970 and1987 to 1992) as well as to periods of respite from climate change (believe it or not, the average global temp hasn’t risen since around 2000).

On top of everything else, contends Chavez, there is some indication of currents bringing warm water up from the south. While evidence is sparse, he thinks this is a contributing factor to the overall warming and is somehow linked to El Nino’s effects.

Back to The Summer of Crazy.

This pretty great video by NASA's ScienceCast explains the relationship between El Nino and Kelvin waves and explains why scientists thought 2014 might be an epic El Nino year.