Freshwater distribution in the Arctic Ocean: Simulation with a high-resolution model and model-data comparison

Abstract. The HYCOM-NORWECOM modeling system is used both for basic research and as a part of the forecasting system for the Arctic Marine Forecasting Centre through the MyOcean project. Here we present a revised version of this model. The present model, as well as the sensitivity simulations leading up to this version, has been compared to a dataset of in-situ measurements of nutrient and chlorophyll from the Norwegian Sea and the Atlantic sector of the Arctic Ocean. The revisions having most impact included adding diatoms to the diet of micro-zooplankton, increasing micro-zooplankton grazing rate and decreased silicate-to-nitrate ratio in diatoms. Model runs are performed both with a coarse- (~50 km) and higher-resolution (~15 km) model configuration, both covering the North Atlantic and Arctic Ocean. While the new model formulation improves the results in both the coarse- and high-resolution model, the nutrient bias is smaller in the high-resolution model, probably as a result of the better resolution of the main processes and with that improved circulation. The final revised version delivers satisfactory results for all three nutrients as well as improved result for chlorophyll in terms of the annual cycle amplitude. However, for chlorophyll the correlation with in-situ data remains relatively low. Besides the large uncertainties associated with observational data this is possibly caused by the fact that constant C / N and Chl / N ratios are implemented in the model.

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Arctic sea level variability from high-resolution model simulations and implications for the Arctic observing system

10.5194/os-2021-79 ◽

2021 ◽

Author(s):

Guokun Lyu ◽

Nuno Serra ◽

Meng Zhou ◽

Detlef Stammer

Keyword(s):

High Resolution ◽

Arctic Ocean ◽

Sea Level ◽

The Arctic ◽

Sea Level Variability ◽

Model Simulations ◽

Marginal Seas ◽

Resolution Model ◽

High Resolution Model ◽

Canadian Basin

Abstract. Two high-resolution model simulations are used to investigate the spatio-temporal variability of the Arctic Ocean sea level. The model simulations reveal barotropic sea level variability at periods < 30 days, which is strongly captured by bottom pressure observations. The seasonal sea level variability is driven by volume ex-changes with the Pacific and Atlantic Oceans and the redistribution of the water by the wind. Halosteric effects due to river runoff and evaporation minus precipitation (EmPmR), ice melting/formation also contribute in the marginal seas and seasonal sea ice extent regions. In the central Arctic Ocean, especially the Canadian Basin, the decadal halosteric effect dominates sea level variability. Satellite altimetric observations and Gravity Re-covery and Climate Experiment (GRACE) measurements could be used to infer freshwater content changes in the Canadian Basin at periods longer than one year. The increasing number of profiles seems to capture fresh-water content changes since 2007, encouraging further data synthesis work with a more complicated interpola-tion method. Further, in-situ hydrographic observations should be enhanced to reveal the freshwater budget and close the gaps between satellite altimetry and GRACE, especially in the marginal seas.

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Arctic sea level variability from high-resolution model simulations and implications for the Arctic observing system

Ocean Science ◽

10.5194/os-18-51-2022 ◽

2022 ◽

Vol 18 (1) ◽

pp. 51-66

Author(s):

Guokun Lyu ◽

Nuno Serra ◽

Meng Zhou ◽

Detlef Stammer

Keyword(s):

High Resolution ◽

Arctic Ocean ◽

Sea Level ◽

The Arctic ◽

Sea Level Variability ◽

Model Simulations ◽

Marginal Seas ◽

Resolution Model ◽

High Resolution Model ◽

Canadian Basin

Abstract. Two high-resolution model simulations are used to investigate the spatiotemporal variability of the Arctic Ocean sea level. The model simulations reveal barotropic sea level variability at periods of < 30 d, which is strongly captured by bottom pressure observations. The seasonal sea level variability is driven by volume exchanges with the Pacific and Atlantic oceans and the redistribution of the water by the wind. Halosteric effects due to river runoff and evaporation minus precipitation ice melting/formation also contribute in the marginal seas and seasonal sea ice extent regions. In the central Arctic Ocean, especially the Canadian Basin, the decadal halosteric effect dominates sea level variability. The study confirms that satellite altimetric observations and Gravity Recovery and Climate Experiment (GRACE) could infer the total freshwater content changes in the Canadian Basin at periods longer than 1 year, but they are unable to depict the seasonal and subseasonal freshwater content changes. The increasing number of profiles seems to capture freshwater content changes since 2007, encouraging further data synthesis work with a more complicated interpolation method. Further, in situ hydrographic observations should be enhanced to reveal the freshwater budget and close the gaps between satellite altimetry and GRACE, especially in the marginal seas.

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High resolution mapping of the Arctic Ocean deepest area: Molloy Hole

10.5194/egusphere-egu21-16227 ◽

2021 ◽

Author(s):

Roberta Ivaldi ◽

Maurizio Demarte ◽

Massimiliano Nannini ◽

Giuseppe Aquino ◽

Cosimo Brancati ◽

...

Keyword(s):

Sustainable Development ◽

High Resolution ◽

Arctic Ocean ◽

The Arctic ◽

Joint Research ◽

Ocean Science ◽

Global Geodynamics ◽

The Arctic Ocean ◽

Seabed Mapping ◽

Resolution Mapping

<p>New hydro-oceanographic data were collected in the Arctic Ocean during HIGN NORTH20 marine geophysical campaign performed in July 2020, in a COVID-19 pandemic period. HIGH NORTH20 was developed as part of the IT-Navy HIGH NORTH program, a Pluriannual Joint Research Program in the Arctic devoted to contribute to oceans knowledge in order to ensure ocean science improving conditions for sustainable development of the Ocean in the aim of United Nations Decade of Ocean Science for Sustainable development and the GEBCO - SEABED 2030 project. In order to contribute in exploration and high-resolution seabed mapping new data was collected using a multibeam echosounder (EM 302 - 30 kHz). The particular sea ice environmental condition with open-sea allowed to survey and mapping the Molloy Hole, the deepest sector of the Arctic Ocean, a key area in the global geodynamics and oceanographic context. A 3D model of the Molloy Hole (804 km<sup>2</sup>) and the detection of the deepest seafloor (5567m - 79&#176; 08.9&#8217; N 002&#176; 47.0&#8217; E) was obtained with a 10x10m grid in compliance to the IHO standards.</p>

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Dynamics in the Deep Canada Basin, Arctic Ocean, Inferred by Thermistor Chain Time Series

Journal of Physical Oceanography ◽

10.1175/jpo3032.1 ◽

2007 ◽

Vol 37 (4) ◽

pp. 1066-1076 ◽

Cited By ~ 12

Author(s):

M-L. Timmermans ◽

H. Melling ◽

L. Rainville

Keyword(s):

Time Series ◽

High Resolution ◽

Internal Wave ◽

Arctic Ocean ◽

Temperature Fluctuations ◽

Canada Basin ◽

The Arctic ◽

The Arctic Ocean ◽

Vertical Displacements ◽

Wave Energy Flux

Abstract A 50-day time series of high-resolution temperature in the deepest layers of the Canada Basin in the Arctic Ocean indicates that the deep Canada Basin is a dynamically active environment, not the quiet, stable basin often assumed. Vertical motions at the near-inertial (tidal) frequency have amplitudes of 10– 20 m. These vertical displacements are surprisingly large considering the downward near-inertial internal wave energy flux typically observed in the Canada Basin. In addition to motion in the internal-wave frequency band, the measurements indicate distinctive subinertial temperature fluctuations, possibly due to intrusions of new water masses.

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