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ARC-COP with coarse measurements (mm) (left) and the ARC-COP at Ella Island (right).

ARC-COP with coarse measurements (mm) (left) and the ARC-COP at Ella Island (right).

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The rapid warming of our planet has resulted in accelerated melting of ice in polar regions. Currently we have limited knowledge on how, where and when the surface meltwater layer is mixed with the underlying ocean due to lack of observations in these remote areas. We present a lightweight (17 kg) and low-cost (6000€) instrument for autonomous prof...

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... ARC-COP instruments were deployed in the Ella Ø fjord system (72.5°N, 25.5°W) in NE Greenland during August 2020. These fjords are several hundred meters deep and connect the Greenland ice sheet with the Greenland Sea (Fig. 11). The ARC-COP was deployed from a small boat. Two modes were applied: (a) a free-floating mode and (b) a moored mode, where the instrument was anchored to the seafloor. In both modes, the profiler was able to control its dives with a speed of 12 ± 0.3 cm/s, resulting in 510 ± 22 data points per 100 m dive with the low-cost Atlas sensor. ...
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... instrument drifted 30-60 m between individual profiles due to sea currents. In the moored mode, the instrument was anchored to the sea floor by a 4 kg folding grapnel anchor, with a Ø3 mm Dyneema mooring line travelling through the handle of the ARC-COP and tightened to a 4-liter trawl float at the surface. Examples of test results are shown on Fig. ...
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... ARC-COP performed well in the moored mode, where the instrument was anchored to the seafloor at 20 m water depth with a Ø3 mm Dyneema line. The line was loose and a few meters longer than the water depth. The instrument was programmed to dive every second hour in the upper water layers where the strongest temperature and salinity gradients exist (Fig. 13). The data show that the ARC-COP was able to dive at regular intervals and record temporal variability of temperature and salinity conditions from close to the bottom to the surface. The instrument reached the surface during each dive cycle. Conditions under the deployment ranged from relatively calm conditions (3-5 m/s and ~ 0.2 m ...
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... software should be written so that the CTD measures while the buoyancy is being changed. This will increase the measurement resolution and can be done with multithreading (fake parallel execution) on the Arduino. Another solution could be using another or an additional microcontroller. Fig. 13. The ARC-COP in mooring mode profiling on a fixed position. Instrument was set profiling every two hour in the upper water layers to record temperature (above) and salinity (below) conditions. Instrument was deployed off Ella Ø À 16th of August 15:24. Black dots are average of 1-m binned ...