How buoys measure ocean weather conditions

Sofar Ocean

The first buoys deployed en masse to measure ocean conditions were envisioned as individual weather stations to help guide flights over the Atlantic.

We’ve come a long way since the first transatlantic flight in 1927; today’s distributed sensor arrays produce the best weather forecasts. Dense readings from a variety of advanced sensors can help meteorologists, climate scientists, and shipping companies better navigate and monitor the ocean. 

Ocean buoys come in all shapes and sizes Their arrangement determines what data can observed over time. Marine electronics are becoming rapidly more robust and durable: here are the different types of ocean weather buoys today and how this technology is improving for the future. 

Types of ocean weather buoys

Weather buoys can be equipped in drifting and moored configurations, anywhere from coastlines to extreme seas offshore. 

Drifting buoys sit at the surface of the ocean and are transported via ocean eddies. They are sometimes attached to some form of drogue — a funnel-shaped device used to keep stable through winds and currents. Drifting buoys tend to be made of fiberglass or plastic; the surface float typically measures 30.5 cm to 40 cm in diameter, while the drogue diameter is approximately 61 cm.

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Comparatively, moored buoys are fixed to the ocean floor using chains, nylon, or buoyant polypropylene — although developing initiatives are tackling interoperable solutions to marine sensor integration.

Moored buoys typically range from 1.5–12 meters (5–40 ft) in diameter and can collect a wide variety of vertical readings down the water column with different atmospheric and oceanographic sensors. . Moored buoys played a significant role in understanding ENSO in the 1980s - 1990s. 

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Within the broad drifter and moored buoy categories are weather buoys that are specially designed for harsh environments. Ice buoys, for instance, are crafted for use in the Arctic and Antarctica to track ice movement. These buoys are equipped with low-temperature electronics and lithium batteries that can operate at -50°C. 

Finally, buoy arrays, such as the Tropical Moored Buoy Implementation Panel array, are used to monitor large-scale ocean phenomena, such as ENSO and climate change. NOAA has deployed buoys in the ocean in large arrays across the Pacific, Atlantic, and Indian oceans to increase data capture and improve modeling. 

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What ocean weather conditions do buoys measure?

Drifting and moored buoys — interoperable or not — can capture a range of marine weather conditions. Different configurations allow buoys to expand their data capture. 

All drifter buoys measure sea surface temperature (SST) and location, which can be used to calculate the velocity of the ocean current. Drifters use a sea surface temperature sensor at the bottom of the surface float to capture temperature. Beyond location and SST, more sensors can be added to the drifter buoy to allow it to capture additional data. Sofar Ocean’s Spotter buoy, for instance, can capture wind speed, wind direction, and wave data: complete wave spectrum, directional moments, and bulk statistics.

Moored buoys tend to be located closer to the coastline, and measure wave height and period, barometric pressure, air, and sea surface temperature, wind speed, wind direction, and even the direction of wave propagation, depending on the configuration. Smart Mooring can measure infragravity waves, non-tidal residuals, tides, and water levels. Different configurations of Smart Mooring for aquaculture can also measure water quality, water column stratification, sub-surface water properties, and currents. 

Buoys in the ocean can essentially be configured and equipped with sensors to measure a wide range of variables. The biggest limitation on ocean weather buoys is the harsh conditions of the ocean itself. 

Innovations in ocean weather buoy technology

Historically, moored and surface buoys have been difficult to deploy. “The cables can be more than three miles long, and the instruments and floats have to withstand corrosion, freezing cold, pressure up to 10,000 pounds per square inch, powerful currents, surging waves, and even fish that mistake them for food,” wrote the Woods Hole Oceanographic Institute

Sofar Ocean is innovating on weather buoy design by using materials built to withstand the harshest environments. Every part of Spotter is built to withstand the elements in any water condition, anywhere on the planet. Its size makes it extremely portable, too: roughly the size of a basketball, Spotter can be shipped anywhere around the world, carried by hand, and deployed without any special equipment. The Smart Mooring uses a polyurethane cable with Kevlar braid, built to withstand the harshest marine environments.

Where do ocean buoys fit into the future of marine sensing? In 2019, the US Department of Energy announced a $3 million incentive to design ocean observing platforms that ran on renewable energy. Currently underway, the Powering the Blue Economy™: Ocean Observing Prize seeks new designs that integrate marine renewable energy with ocean observation platforms, with the goal of advancing data collection to understand and monitor the ocean.
While many buoys use solar panels to stay up and running, the opportunity to use marine-based renewable energy is promising. To learn more about buoys in the ocean, and to be informed of the latest trends in ocean buoy technology, check out the Sofar Ocean blog.

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