Remotely Piloted Sailboats Will Help Monitor Tropical Ocean "Cold Pools"

Atmospheric and ocean researchers know that conditions in the tropical ocean impacts weather patterns worldwide. Two well-known examples of patterns that start in the tropical climate and impact global weather patterns are El Niño and La Niña. However, while those two weather conditions are well known and publicized, scientists believe there are other key elements in the tropical climate impacting global weather conditions that are undiscovered.

A recent study from scientists at the University of Washington and the NOAA Pacific Marine Environmental Laboratory used remotely-piloted sailboats to gather data on a phenomenon known as cold air pools. Cold air pools are pockets of cooler air from below tropical storm clouds, flowing outward beneath intense thunderstorms that can alter the surrounding environment.

These so-called cold pools are a key source of variability for surface temperatures and in wind and moisture over the ocean. The study is one of the first papers focusing on the tropical Pacific to rely on data from remotely-piloted sailboats called Saildrones. These drones are powered by the wind utilizing a tall and rigid wing along with solar-powered scientific instruments. Their design allows them to travel long distances and to remain in the environment for extended time frames.

Researchers have discovered that the atmospheric cold pool can produce dramatic changes in air temperature and wind speed near the surface of the tropical ocean. The pockets of cooler air form as rain evaporates below thunderstorm clouds. That creates relatively dense air masses ranging between six and 125 miles across and leads to downdrafts impacting the ocean's surface and producing temperature fronts and strong winds impacting the surroundings.

Researchers admit that how exactly the phenomenon impacts larger atmospheric circulation is unknown at this time. Past studies showed that cold pools are important for triggering and organizing storm activity over tropical ocean regions. Researchers say that to understand the role cold pools play in the tropical climate cycle, they need more measurements of the events, but the events are hard to witness as they happen. The remotely-piloted sailboats will help provide the data needed. The drones allow observations to be gathered across difficult-to-reach and under-sampled ocean regions for extended periods.