The Ocean Colour System Gets a ‘Refresh,’ Permitting More Precise and Accurate Measurements
We typically think of the ocean’s colour as blue, but in some regions, it looks blue-green. That’s due to the fact that those regions are teeming with single-cell plants named phytoplankton, which contain chlorophyll and reflect the green in sunshine. Though small, phytoplankton collectively absorbs almost as much co2 as all the trees and land plants on Earth. They have an enormous impact on our environment, and researchers research study that effect by measuring the colour of the ocean with satellites and sea-based sensors.
To guarantee satellite measurements are accurate, scientists in the united state and several other countries rely on an ocean-colour sensing unit called the Marine Optical Buoy (MOBY). Now, the National Oceanic and also Atmospheric Administration (NOAA), Moss Landing Marine Labs (MLML), the College of Miami, and also the National Institute of Standards and Technology (NIST) have worked together on an upgrade to the sensor called as MOBY-Refresh, that will allow more precise and precise measurements of sunlight’s colours or wavelengths.
“MOBY measures how much light over a ranietyge of wave lengths is being scattered out of the water at a singular place in the Pacific Ocean. The ocean-colour satellite sensors observe the oceans, including the MOBY site. The MOBY information after that are delivered to the satellite groups, which utilize the data to adjust the satellite sensing units’ calibration, therefore enhancing the accuracy of the worldwide data products such as the focus of chlorophyll,” described NIST scientist Carol Johnson.
MOBY consists of 2 primary buoys: the optical buoy, that measures and records light, and the mooring buoy, which maintains the optical buoy in place.
The optical buoy has a main mast that extends undersea. The mast has 3 pole-like arms, each with optical fibers that collect light. The optical fiber collectors spot light at depths of one meter (3.3 feet), 5 meters (16.4 feet), and nine meters (29.4 feet). At the bottom of the main mast are spectrographs that measure light as a function of wavelength at each of the 3 depths.
MOBY is located twenty kilometers (twelve miles) off the coastal zone of Lanai, Hawaii, because this location gives optimal climatic and water conditions for calibrating ocean-color satellite sensor systems. The ocean water there is representative of the rest of the globe´s oceans as it is clear and has a low degree of chlorophyll. The atmosphere is clear with few clouds that guarantee the usefulness of the measurements on a world scale.
“The life cycle of the optical buoy is about 4 months, and there are 2 complete systems. The one in the water is recuperated on the same cruise as the current one is deployed,” said Johnson. “The one in the water takes information, and the one recovered is refurbished for the following operation,” she stated. MOBY has been in operation since 1997 and is presently on its 74th deployment of the optical buoy.
In the Refresh project, MOBY is being upgraded with a current optical system, support frameworks, and control system. The objective was to replace the aging hardware and decrease uncertainties in the measurements. A 2nd mooring buoy was deployed in January 2021, and the initial upgraded optical buoy was deployed there in late February 2022. Johnson said that analyzing the data is ongoing; however, initial comparisons to MOBY Buoy276, currently in the ocean, are highly encouraging.
For the optical system, the upgrade consists of an enhanced spectrograph that can measure sunshine at all 3 depths simultaneously, which reduces ecological sources of uncertainty, including fluctuations in buoy tilt and also arm depth and the changes in light as it is focused by ocean waves. The optical buoy is currently made of carbon fiber, whereas before, it was made from fiber glass and steel, making the structure more robust and increasing its lifetime at sea.
In parallel to MOBY-Refresh, the group is developing similar instrumentation called MarONet, which will be utilized by an upcoming NASA satellite mission known as PACE (Plankton, Aerosol, Cloud, ocean Ecosystem). The tool design of the optical system will be the same as Refresh however features a more mobile buoy.
In the MarONet project, the optical system could be disassembled and taken to a primary location for calibration and characterization. Calibration explains how the tool output relies on the input. Characterization explains how this relationship changes with all possible influencing aspects, such as ambient temperature level. The deployment site for the MarONet buoy will be off the coast of Western Australia. The central place for calibration and maintenance of the buoy will remain in Hawaii, where the central MOBY hub is located. NIST’s role in this procedure will be to look for any changes in the optical system during transport. The site planning for Australia has started under the direction of co-researcher David Antoine of Curtin College in Perth. In 2023, the optical and mooring buoy devices will be shipped to Australia.
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