Scripps Institution of Oceanography researchers waded into the chilly waters of Los Penasquitos lagoon on Friday preparing to paint the ocean pink.
Brian Woodward, a research and development engineer at Scripps, dropped a small buoy just a few feet from shore. That buoy drifted in the tide driven fresh water with a long plastic hose firmly attached.
“We’ve got a lot of moving pieces here,” Woodward said.
Shortly after 9 a.m., the team began pumping nontoxic pink dye through the hose and out into the lagoon.
It did not take long for the tide driven fresh water to start pushing the dye out into the rough winter surf.
Woodward’s team was prepared to record everything they could think of. There were sensors attached to stakes in the ocean.
“We’ve got the jet ski,” Woodward said as he pointed to the jet propelled vehicle bobbing in the waves. “I don’t know if you noticed, it’s got fluorometers, CTD's (measuring) temperature, depth, connectivity, measuring salt, things like that. It’s also measuring the bathymetry.”
Researchers also had drones in the sky. One was shooting regular high definition video, another used a hyper spectral camera that allowed the team to track the dye as it moved away from the lagoon.
Scientists know a lot about how big rivers interact with the ocean, but not so much about the many rivers that work on a smaller scale. They're hoping tracking the dye will bring them closer to understanding.
Estuaries like this coastal lagoon send sediments and contaminants into the ocean.
“These very small river plumes interact directly with the surf zone in that the breaking waves have an impact on their ultimate spreading,” said Sarah Giddings, the lead researcher on the dye project.
Giddings chose Friday morning for the dye release because a high tide was receding and that helped push the lighter freshwater out of the lagoon and into the heavy saltwater.
The team wanted a day when winter waves were rolling toward shore, pushing back at the freshwater plume.
“The waves can effectively trap the river plume in the surf zone, such that it spreads along the shore instead of punching offshore,” Giddings said. “And so we’re sort of trying to understand that transition between when it punches offshore and spreads off shore versus when it gets trapped in the surf zone and spreads along shore.”
The painted water quickly began mixing with the surf, and researchers tracking the dye with drones say it quickly moved south, along the coast.
The team has used the environmentally-friendly pink dye for ocean experiments before.
Back in 2015, Scripps researchers released the pink dye just off the Southern San Diego County coast and off the coast of Mexico in an effort to track how pollution moves once it hits the ocean.
