scholarly journals Time series of temperature in Fram Strait determined from the 2008–2009 DAMOCLES acoustic tomography measurements and an ocean model

2016 ◽  
Vol 121 (7) ◽  
pp. 4601-4617 ◽  
Author(s):  
Hanne Sagen ◽  
Brian D. Dushaw ◽  
Emmanuel K. Skarsoulis ◽  
Dany Dumont ◽  
Matthew A. Dzieciuch ◽  
...  
Keyword(s):  
Time Series ◽  
Ocean Model ◽  
Acoustic Tomography ◽  
Fram Strait

A Comparative Study of Moored/Point and Acoustic Tomography/Integral Observations of Sound Speed in Fram Strait Using Objective Mapping Techniques

2016 ◽  
Vol 33 (10) ◽  
pp. 2079-2093 ◽  
Author(s):  
Brian D. Dushaw ◽  
Hanne Sagen
Keyword(s):  
Sound Speed ◽  
Heat Content ◽  
Ocean Model ◽  
The Arctic ◽  
Mooring Line ◽  
Acoustic Tomography ◽  
Fram Strait ◽  
Data Types ◽  
Parameterized Model ◽  
Ocean Environment

AbstractEstimation of the exchange of seawater of various properties between the Arctic and North Atlantic Oceans presents a challenging observational problem. The strong current systems within Fram Strait induce recirculations and a turbulent ocean environment dominated by mesoscale variations of 4–10-km scale. By employing a simple parameterized model for mesoscale variability within Fram Strait, the authors examine the ability of a line array of closely spaced moorings and an acoustic tomography line to measure the average sound speed, a proxy variable for ocean temperature or heat content. Objective maps are employed to quantify the uncertainties resulting from the different measurement approaches. While measurements by a mooring line and tomography result in similar uncertainties in estimations of range- and depth-averaged sound speed, the combination of the two approaches gives uncertainties 3 times smaller. The two measurements are sufficiently different as to be complementary; one measurement provides resolution for the aspects of the temperature section that the other misses. The parameterized model and its assumptions as to the magnitudes and scales of variability were tested by application to a hydrographic section across Fram Strait measured in 2011. This study supports the deployment of the 2013–16 Arctic Ocean under Melting Ice (UNDER-ICE) network of tomographic transceivers spanning the ongoing moored array line across Fram Strait. Optimal estimation for this ocean environment may require combining disparate data types as constraints on a numerical ocean model using data assimilation.

Implementation and Validating of the Regional Ocean Model System (ROMS) for the Sunda Strait connecting the Java Sea to the Indian Ocean

2021 ◽  
Author(s):  
Subekti Mujiasih ◽  
Jean-Marie Beckers ◽  
Alexander Barth
Keyword(s):  
Time Series ◽  
Indian Ocean ◽  
Vertical Profile ◽  
Ocean Model ◽  
Model System ◽  
Satellite Sst ◽  
Regional Ocean Model System ◽  
Regional Ocean Model ◽  
The Indian Ocean ◽  
Java Sea

<p>Regional Ocean Model System (ROMS) has been simulated for the Sunda Strait, the Java Sea, and the Indian Ocean. The simulation was undertaken for thirteen months of data period (August 2013 – August 2014). However, we only used four months period for validation, namely September – December 2013. The input data involved the HYbrid Coordinate Ocean Model (HYCOM) ocean model output by considering atmospheric forcing from the European Centre for Medium-Range Weather Forecasts (ECMWF), without and with tides forcing from TPXO and rivers. The output included vertical profile temperature and salinity, sea surface temperature (SST), seas surface height (SSH), zonal (u), and meridional (v) velocity. We compared the model SST to satellite SST in time series, SSH to tides gauges data in time series, the model u and v component velocity to High Frequency (HF) radial velocity. The vertical profile temperature and salinity were compared to Argo float data and XBT. Besides, we validated the amplitude and phase of the ROMS seas surface height to amplitude and phase of the tides-gauges, including four constituents (M2, S2, K1, O1).</p>

scholarly journals Novel Method for the Estimation of Vertical Temperature Profiles Using a Coastal Acoustic Tomography System

2021 ◽  
Vol 8 ◽  
Author(s):  
Yeongbin Park ◽  
Chanhyung Jeon ◽  
Hajin Song ◽  
Youngseok Choi ◽  
Jeong-Yeob Chae ◽  
...  
Keyword(s):  
Temperature Profile ◽  
Coastal Region ◽  
Ocean Model ◽  
Acoustic Tomography ◽  
Observation Data ◽  
Random Errors ◽  
Vertical Temperature ◽  
Vertical Temperature Profile ◽  
Marine Aquaculture ◽  
Novel Method

Systems based on remote sensing technology, which use reciprocal acoustic signals to continuously monitor changes in the coastal oceanic environment, are referred to as coastal acoustic tomography (CAT) systems. These systems have been applied in regions in which heavy ship traffics, fishing and marine aquaculture activities make it difficult to establish in situ oceanic sensor moorings. Conventionally, CAT measurements were used to successfully produce horizontal maps of the depth-averaged current velocity and temperature in these coastal regions without attempting to produce a vertical temperature profile. This prompted us to propose a new method for vertical temperature profile estimation (VTPE) from CAT data using the available sea surface temperature (SST), near-bottom temperature (NBT), and water depth. The VTPE method was validated using data-assimilated and tide-included high-resolution ocean model outputs, including tide data, by comparing the estimated and simulated temperatures. Measurements were performed in the southern coastal region of Korea, where two CAT stations were moored to establish a continuous coastal ocean monitoring system. The validation results revealed that the algorithm performed well across all seasons. Sensitivity tests of the VTPE method with reasonable realistic random errors in the SST, NBT, and acoustic travel time measurements demonstrate that the method is applicable to CAT observation data because the monthly mean root-mean-squared difference (RMSD) for the vertical profiles for February, May, August, and November were 0.23, 0.30, 0.50, and 0.24°C, respectively. The VTPE method was applied to the CAT observation datasets acquired in February and August. The transceivers at the CAT stations were at depths 11 and 6 m on average. The RMSD between the estimated and observed temperatures in the middle layer (∼3 m depth) between two stations in February and August were 0.08 and 0.60°C, respectively, the accuracy of which is sufficient in largely time-varying coastal environments. We provide a novel method for continuous coastal subsurface environmental monitoring without interrupting maritime traffic, fishing, and marine aquaculture activities.

scholarly journals Interannual variability in Transpolar Drift ice thickness and potential impact of Atlantification

2020 ◽  
Author(s):  
H. Jakob Belter ◽  
Thomas Krumpen ◽  
Luisa von Albedyll ◽  
Tatiana A. Alekseeva ◽  
Sergei V. Frolov ◽  
...  
Keyword(s):  
Time Series ◽  
Sea Ice ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Ice Thickness ◽  
Fram Strait ◽  
Ice Growth ◽  
Arctic Sea ◽  
Transpolar Drift ◽  
The Impact

Abstract. Changes in Arctic sea ice thickness are the result of complex interactions of the dynamic and variable ice cover with atmosphere and ocean. Most of the sea ice exits the Arctic Ocean through Fram Strait, which is why long-term measurements of ice thickness at the end of the Transpolar Drift provide insight into the integrated signals of thermodynamic and dynamic influences along the pathways of Arctic sea ice. We present an updated time series of extensive ice thickness surveys carried out at the end of the Transpolar Drift between 2001 and 2020. Overall, we see a more than 20 % thinning of modal ice thickness since 2001. A comparison with first preliminary results from the international Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) shows that the modal summer thickness of the MOSAiC floe and its wider vicinity are consistent with measurements from previous years. By combining this unique time series with the Lagrangian sea ice tracking tool, ICETrack, and a simple thermodynamic sea ice growth model, we link the observed interannual ice thickness variability north of Fram Strait to increased drift speeds along the Transpolar Drift and the consequential variations in sea ice age and number of freezing degree days. We also show that the increased influence of upward-directed ocean heat flux in the eastern marginal ice zones, termed Atlantification, is not only responsible for sea ice thinning in and around the Laptev Sea, but also that the induced thickness anomalies persist beyond the Russian shelves and are potentially still measurable at the end of the Transpolar Drift after more than a year. With a tendency towards an even faster Transpolar Drift, winter sea ice growth will have less time to compensate the impact of Atlantification on sea ice growth in the eastern marginal ice zone, which will increasingly be felt in other parts of the sea ice covered Arctic.

Ocean acoustic tomography: Travel‐time inversion in the eastern Fram Strait

2008 ◽  
Vol 123 (5) ◽  
pp. 2991-2991
Author(s):  
Emmanuel Skarsoulis ◽  
George Piperakis ◽  
Michael Kalogerakis ◽  
Hanne Sagen
Keyword(s):  
Travel Time ◽  
Acoustic Tomography ◽  
Time Inversion ◽  
Fram Strait ◽  
Travel Time Inversion ◽  
Ocean Acoustic Tomography

Acoustic tomography as a component of the Fram Strait observing system

2012 ◽  
Vol 132 (3) ◽  
pp. 1914-1914
Author(s):  
Brian D. Dushaw ◽  
Hanne Sagen ◽  
Stein Sandven ◽  
Peter Worcester
Keyword(s):  
Acoustic Tomography ◽  
Fram Strait

scholarly journals Using a regional ocean model to understand the structure and variability of acoustic arrivals in Fram Strait

2020 ◽  
Vol 147 (2) ◽  
pp. 1042-1053
Author(s):  
Florian Geyer ◽  
Hanne Sagen ◽  
Bruce Cornuelle ◽  
Matthew R. Mazloff ◽  
Heriberto J. Vazquez
Keyword(s):  
Ocean Model ◽  
Fram Strait ◽  
Regional Ocean Model
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