Under-ice current measurements during MOSAiC from a 75 kHz acoustic Doppler profiler

Baumann, Till; Fer, Ilker; Bryhni, Helge Thomas; Peterson, Algot Kristoffer; Allerholt, Jacob; Fang, Ying-Chih; Hoppmann, Mario; Karam, Salar; Koenig, Zoé; Kong, Bin; Mohrholz, Volker; Muilwijk, Morven; Schaffer, Janin; Schulz, Kirstin; Sukhikh, Natalia; Tippenhauer, Sandra

doi:10.1594/pangaea.934792

Cited by 4 publications

(3 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Current velocity profiles (approximately 20-400 m depth) obtained with a 75 kHz acoustic Doppler current profiler (ADCP; Baumann et al, 2021) were used to calculate depth-averaged surface layer (14-30 m) and tidal (whole water depth) currents of different frequencies (see Meyer et al, 2017b, and supplemental Text S1 for more details in the methodology) and to visually identify eddies.…”

Section: Methods and Instrumentationmentioning

confidence: 99%

The Eurasian Arctic Ocean along the MOSAiC drift in 2019-2020: An interdisciplinary perspective on physical properties and processes

Schulz,

Koenig,

Muilwijk

et al. 2024

Preprint

View full text Add to dashboard Cite

The Multidisciplinary drifting Observatory for the Study of the Arctic Climate (MOSAiC, 2019/2020), a year-long drift with the Arctic sea ice, has provided the scientific community with an unprecedented, multidisciplinary dataset from the Eurasian Arctic Ocean, covering high atmosphere to deep ocean across all seasons. However, the heterogeneity of data and the superposition of spatial and temporal variability, intrinsic to a drift campaign, complicate the interpretation of observations. In this study, we compile a quality-controlled hydrographic dataset with best spatio-temporal coverage and derive core parameters, including the mixed layer depth, heat fluxes over key layers, and friction velocity. We provide a comprehensive and accessible overview of the ocean conditions encountered along the MOSAiC drift, discuss their interdisciplinary implications, and compare common ocean climatologies to these new data. Our results indicate that - for the most parts - ocean variability was dominated by regional, rather than seasonal signals, with potentially strong implications for ocean biogeochemistry, ecology, sea ice, and even atmospheric conditions. Near-surface ocean properties are strongly influenced by the relative position of sampling within or outside the river-water influenced Transpolar Drift, and seasonal warming and meltwater input. Ventilation down to the Atlantic Water layer in the Nansen Basin allows for a stronger connectivity to both sea ice and surface ocean, including elevated upward heat fluxes. The Yermak Plateau and Fram Strait region are characterized by variable conditions, strong ocean currents, a stronger influence of Atlantic Water, and substantial lateral gradients in surface water properties in frontal regions. Together with the presented results and core parameters, we offer context for interdisciplinary research, fostering an improved understanding of the complex, coupled Arctic System.

show abstract

Section: Methods and Instrumentationmentioning

confidence: 99%

The Eurasian Arctic Ocean along the MOSAiC drift in 2019-2020: An interdisciplinary perspective on physical properties and processes

Schulz,

Koenig,

Muilwijk

et al. 2024

Preprint

View full text Add to dashboard Cite

show abstract

“…Data sets from HM Jul 2007 and HM Sep 2014 are under preparation and will be made available at the Norwegian Marine Data Centre. ADCP and MSS data from MOSAiC are openly available (Baumann et al, 2021;Schulz et al, 2022b).…”

Section: Data Availability Statementmentioning

confidence: 99%

Validating Finescale Parameterizations for the Eastern Arctic Ocean Internal Wave Field

Baumann,

Fer,

Schulz

et al. 2023

JGR Oceans

Self Cite

View full text Add to dashboard Cite

In the Arctic Ocean, vertical transport of heat by turbulent mixing is ultimately coupled to the sea‐ice cover, with immediate and far‐reaching impacts on the climate and ecosystem. Unfortunately, direct observations of mixing are difficult, expensive and sparse. Finescale Parameterization (FS) of turbulent energy dissipation rate (ɛ) allows for the quantification of turbulence from breaking internal waves using standard measurements, such as profiles of hydrography and velocity. While FS proved to be reliable in mid‐latitudes, the Arctic Ocean internal wave field is distinct in terms of composition and energy level, rendering the applicability of FS uncertain. To test FS in a wide range of eastern Arctic conditions, we compiled data from eight cruises. All profiles used to calculate FS were collocated with in‐situ measurements of ɛ obtained from microstructure profilers. FS was applied between 50 and 450 m below the surface. Results show a satisfactory performance of FS, with 84% of FS‐derived ɛ being within a factor of 5 to observations. This improved to 90% when using lower‐noise velocity profiles of lowered current meters instead of ship‐mounted current meters. In our data, FS performance is independent of the shear‐strain ratio (Rω) and internal wave field bandwidth (N/f), but there is evidence that highly stratified environments with large potential energy, low turbulence and substantially non‐white shear spectra are less suitable for FS. A widely used formulation of FS using only hydrography and a prescribed Rω = 7 results in 73% of FS estimates being within a factor of 5 to observations.

show abstract

“…CC BY 4.0 License. However, measurements directly from the MOSAiC experiment show average velocity values of about 1 cm/s at depths of 60-200 meters(Baumann et al (2021)). The average velocity values across the entire area in our simulations range from 1-2 cm/s depending on the depth, with peaks up to 15 cm/s in eddies.…”

mentioning

confidence: 99%

Dynamical reconstruction of the upper-ocean state in the Central Arctic during the winter period of the MOSAiC Expedition

Kuznetsov

Rabe

Androsov

et al. 2023

Preprint

View full text Add to dashboard Cite

Abstract. The Arctic Ocean is a region important for global and regional climate. Although generally quiescent compared to mid-latitudes, the upper Arctic ocean hosts mesoscale and smaller scale processes. These processes can have a profound impact on vertical ocean fluxes, stratification, and feedback with the sea ice and atmosphere. Sparse and non-synoptic in-situ observations of the polar oceans are limited by the distribution of manual observing platforms and autonomous instrumentation. Analyzing observational data to assess tracer field gradients and upper ocean dynamics becomes highly challenging when measurement platforms drift with the ice pack due to continuous changes in drift speed direction. This work presents a dynamical reconstruction of the ocean state, based on observations of the Multidisciplinary Observatory for the Study of Arctic Climate (MOSAiC) experiment. Overall, the model can reproduce the lateral and vertical structure of the temperature, salinity, and density fields, which allows for projecting dynamically consistent features of these fields onto a regular grid. We identify two separate depth ranges of enhanced eddy kinetic energy, which are located around two maxima in buoyancy frequency: the depth of the upper halocline and the depth of the warm (modified) Atlantic Water. Simulations reveal a notable decrease in surface layer salinity and density towards the north, accompanied by high variability in the mixed layer depth in the south-north direction. And no significant horizontal gradients in salinity and density fields but an increase in mixed layer depth from west to east 0.084 m/km gradient with 0.6 m/km standard deviation, indicating opposite characteristics compared to the south-north direction. The model resolves several stationary eddies in the warm Atlantic Water and provides insights into the associated dynamics. The obtained three-dimensional fields of temperature and salinity can be used for further analysis of the thermohaline structure and related dynamics associated with submesoscale processes in the Central Arctic. Dynamic characteristics and eddy fields can be used for further analysis and comparison with state-of-the-art climate and Earth System Models. The developed nudging method can be used to utilize future observational data obtained from a diverse set of instruments.

show abstract

Under-ice current measurements during MOSAiC from a 75 kHz acoustic Doppler profiler

Cited by 4 publications

References 1 publication

The Eurasian Arctic Ocean along the MOSAiC drift in 2019-2020: An interdisciplinary perspective on physical properties and processes

The Eurasian Arctic Ocean along the MOSAiC drift in 2019-2020: An interdisciplinary perspective on physical properties and processes

Validating Finescale Parameterizations for the Eastern Arctic Ocean Internal Wave Field

Dynamical reconstruction of the upper-ocean state in the Central Arctic during the winter period of the MOSAiC Expedition

Contact Info

Product

Resources

About