Continuous observations of the surface energy budget and meteorology over the Arctic sea ice during MOSAiC

Scientific Data, Journal Year: 2023, Volume and Issue: 10(1)

Published: Aug. 4, 2023

The Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) was a yearlong expedition supported by icebreaker R/V Polarstern, following Transpolar Drift from October 2019 to 2020. campaign documented an annual cycle physical, biological, and chemical processes impacting atmosphere-ice-ocean system. Of central importance were measurements thermodynamic dynamic evolution sea ice. A multi-agency international team led University Colorado/CIRES NOAA-PSL observed meteorology surface-atmosphere energy exchanges, including radiation; turbulent momentum flux; latent sensible heat snow conductive flux. There four stations on ice, 10 m micrometeorological tower paired with 23/30 mast radiation station three autonomous Atmospheric Surface Flux Stations. Collectively, acquired ~928 days data. This manuscript documents acquisition post-processing those provides guide researchers access use data products.

Language: Английский

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Sea ice and snow characteristics from year-long transects at the MOSAiC Central Observatory

Elementa Science of the Anthropocene, Journal Year: 2023, Volume and Issue: 11(1)

Published: Jan. 1, 2023

Repeated transects have become the backbone of spatially distributed ice and snow thickness measurements crucial for understanding mass balance. Here we detail at Multidisciplinary drifting Observatory Study Arctic Climate (MOSAiC) 2019–2020, which represent first such collected across an entire season. Compared with similar historical transects, MOSAiC was thin (mean depths approximately 0.1–0.3 m), while sea relatively thick first-year (FYI) second-year (SYI). SYI two distinct types: level formed from surfaces extensive melt pond cover, deformed ice. On SYI, spatial signatures refrozen ponds remained detectable in January. At beginning winter thinnest also had snow, growth rates (0.33 m month−1 FYI, 0.24 previously ponded SYI) exceeding that (0.2 month−1). By January, FYI already a greater modal (1.1 m) than (0.9 m). February, all became indistinguishable about 1.4 m. The largest thicknesses were measured May 1.7 Transects included ice, where volumes accumulated by April. remaining on exhibited typical heterogeneity form dunes. Spatial correlation length scales ranged 20 to 40 or 60 90 m, depending sampling direction, suggests known anisotropy dunes manifests patterns thickness. diverse data obtained invaluable resource model remote sensing product development.

Language: Английский

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Quantifying false bottoms and under-ice meltwater layers beneath Arctic summer sea ice with fine-scale observations

Elementa Science of the Anthropocene, Journal Year: 2022, Volume and Issue: 10(1)

Published: Jan. 1, 2022

During the Arctic melt season, relatively fresh meltwater layers can accumulate under sea ice as a result of snow and melt, far from terrestrial freshwater inputs. Such under-ice layers, sometimes referred to ponds, have been suggested play role in summer mass balance both by isolating saltier water below, driving formation ‘false bottoms’ below ice. form at interface fresher layer colder, seawater below. Multidisciplinary drifting Observatory for Study Climate (MOSAiC) expedition Central Arctic, we observed presence false bottoms throughout July 2020 primarily first-year locations. Here, examine distribution, prevalence, drivers ponds resulting during this period. The average thickness equivalent was 0.08 m, with bottom comprised 74–87% FYI 13–26% melt. Additionally, explore these results using 1D model understand dynamic influences on decoupling comparison suggests that ice-ocean friction velocity likely exceptionally low, implications air-ice-ocean momentum transfer. Overall, prevalence similar or higher than noted other observational campaigns, indicating features may fact be common season. These broader system, provide source growth potentially reduce fluxes between ocean, isolate primary producers pelagic nutrient sources, alter light transmission ocean

Language: Английский

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Sea Ice Melt Pond Fraction Derived From Sentinel‐2 Data: Along the MOSAiC Drift and Arctic‐Wide

Geophysical Research Letters, Journal Year: 2023, Volume and Issue: 50(5)

Published: March 4, 2023

Abstract Melt ponds forming on Arctic sea ice in summer significantly reduce the surface albedo and impact heat mass balance of ice. Therefore, their areal coverage, which can undergo rapid change, is crucial to monitor. We present a revised method extract melt pond fraction (MPF) from Sentinel‐2 satellite imagery, evaluated by MPF products higher‐resolution helicopter‐borne imagery. The analysis evolution during MOSAiC campaign 2020, shows split Central Observatory (CO) into level highly deformed part, latter exhibits exceptional early formation compared vicinity. Average CO MPFs are 17% before 23% after major drainage. Arctic‐wide for years 2017–2021 consistent seasonal cycle all regions years.

Language: Английский

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Thin and transient meltwater layers and false bottoms in the Arctic sea ice pack—Recent insights on these historically overlooked features

Elementa Science of the Anthropocene, Journal Year: 2023, Volume and Issue: 11(1)

Published: Jan. 1, 2023

The rapid melt of snow and sea ice during the Arctic summer provides a significant source low-salinity meltwater to surface ocean on local scale. accumulation this on, under, around floes can result in relatively thin layers upper ocean. Due small-scale nature these upper-ocean features, typically order 1 m thick or less, they are rarely detected by standard methods, but nevertheless pervasive critically important summer. Observations Multidisciplinary drifting Observatory for Study Climate (MOSAiC) expedition 2020 focused evolution such made advancements understanding their role coupled system. Here we provide review Arctic, with emphasis new findings from MOSAiC. Both prior recent observational datasets indicate an intermittent yet long-lasting (weeks months) layer 0.1 1.0 thickness, large spatial range. presence impacts physical system reducing bottom allowing formation via false growth. Collectively, bottoms reduce atmosphere-ocean exchanges momentum, energy, material. far-reaching, including acting as barrier nutrient gas exchange impacting ecosystem diversity productivity.

Language: Английский

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Temporal evolution of under-ice meltwater layers and false bottoms and their impact on summer Arctic sea ice mass balance

Elementa Science of the Anthropocene, Journal Year: 2023, Volume and Issue: 11(1)

Published: Jan. 1, 2023

Low-salinity meltwater from Arctic sea ice and its snow cover accumulates creates under-ice layers below ice. These can result in the formation of new layers, or false bottoms, at interface this low-salinity colder seawater. As part Multidisciplinary drifting Observatory for Study Climate (MOSAiC), we used a combination coring, temperature profiles thermistor strings underwater multibeam sonar surveys with remotely operated vehicle (ROV) to study areal coverage temporal evolution bottoms during summer melt season mid-June until late July. ROV indicated that MOSAiC Central (350 by 200 m2) was 21%. Presence reduced bottom 7–8% due local decrease ocean heat flux, which be described thermodynamic model. Under-ice layer thickness larger first-year thinner thicker second-year We also found thick ridge keels confined areas accumulated, preventing mixing underlying While model could reproduce growth melt, it not describe observed rates above bottoms. show meltwater-layer salinity is linked brine flushing accumulating bottom. The results aid estimating contribution mass balance salt budget

Language: Английский

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The MOSAiC Distributed Network: Observing the coupled Arctic system with multidisciplinary, coordinated platforms

Elementa Science of the Anthropocene, Journal Year: 2024, Volume and Issue: 12(1)

Published: Jan. 1, 2024

Central Arctic properties and processes are important to the regional global coupled climate system. The Multidisciplinary drifting Observatory for Study of Climate (MOSAiC) Distributed Network (DN) autonomous ice-tethered systems aimed bridge gaps in our understanding temporal spatial scales, particular with respect resolution Earth system models. By characterizing variability around local measurements made at a Observatory, DN covers both interactions involving ocean-ice-atmosphere interfaces as well three-dimensional ocean, sea ice, atmosphere. more than 200 instruments (“buoys”) were varying complexity set up different sites mostly within 50 km Observatory. During an exemplary midwinter month, observations captured atmospheric on sub-monthly time but less so monthly means. They show significant snow depth ice thickness, provide temporally spatially resolved characterization motion deformation, showing coherency scale smaller scales. Ocean data background gradient across dependent due mixed layer sub-mesoscale mesoscale processes, influenced by variable cover. second case (May–June 2020) illustrates utility during absence manually obtained providing continuity physical biological this key transitional period. We examples synergies between extensive MOSAiC remote sensing numerical modeling, such estimating skill drift forecasts evaluating modeling. has been proven enable analysis atmosphere-ice-ocean potential improve model parameterizations important, unresolved future.

Language: Английский

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Sea ice heat and mass balance measurements from four autonomous buoys during the MOSAiC drift campaign

Elementa Science of the Anthropocene, Journal Year: 2023, Volume and Issue: 11(1)

Published: Jan. 1, 2023

As part of the Multidisciplinary drifting Observatory for Study Arctic Climate (MOSAiC), four autonomous seasonal ice mass balance buoys were deployed in first- and second-year ice. These measured position, barometric pressure, snow depth, thickness, growth, surface melt, bottom vertical profiles temperature from air, through ice, into upper ocean. Observed air temperatures similar at all sites; however, snow–ice interface varied by as much 10°C, primarily due to differences depth. winter growth rates (November May) <1 cm day−1, with summer melt (June July) large 5 day−1. Air changed 2°C hour−1 but dampened <0.3°C interface. Initial October thicknesses ranged 0.3 m first-year 1.2 By February, this range was only 1.20–1.46 m, onset basal freezing. In delay brine-filled voids ice; propagating cold front required freezing brine. Mass results those North Pole 2000 2013. Winter average estimates ocean heat flux 0 3 W m−2, a increase June 2020 floe moved warmer water. Estimates thermal conductivity two during periods linear 0.41 0.42 m−1 °C−1, higher than previously published estimates. Results these can contribute efforts close MOSAiC budget.

Language: Английский

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Different mechanisms of Arctic first-year sea-ice ridge consolidation observed during the MOSAiC expedition

Elementa Science of the Anthropocene, Journal Year: 2023, Volume and Issue: 11(1)

Published: Jan. 1, 2023

Sea-ice ridges constitute a large fraction of the ice volume in Arctic Ocean, yet we know little about evolution these masses. Here examine thermal and morphological an first-year sea-ice ridge, from its formation to advanced melt. Initially mean keel depth was 5.6 m sail height 0.7 m. The initial rubble macroporosity (fraction seawater filled voids) estimated at 29% drilling 43%–46% buoy temperature. From January until mid-April, ridge consolidated slowly by heat loss atmosphere total layer growth during this phase mid-April mid-June, there sudden increase consolidation rate despite no conductive flux. We surmise change related decreased due transport snow-slush via adjacent open leads. In period, thickness increased 2.1 At peak melt June–July suggest that refreezing surface snow meltwater (the latter only 15% consolidation). used morphology parameters calculate hydrostatic equilibrium obtained more accurate estimate actual keel, correcting 2.2 2.8 for average consolidation. This approach also allowed us 0.3 m, June–July, accompanied decrease draft 0.9 An mass balance indicated which rapid mode April June. By resulted drastic interior while flanks had or macroporosity. These results are important understanding role keels as sources sinks sanctuary ice-associated organisms pack ice.

Language: Английский

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Surface Energy Balance Responses to Radiative Forcing in the Central Arctic From MOSAiC and Models

Journal of Geophysical Research Atmospheres, Journal Year: 2025, Volume and Issue: 130(6)

Published: March 10, 2025

Abstract The Arctic surface energy budget (SEB) couples the atmosphere with sea ice, making it useful for both studying processes as well evaluating models. Improved understanding of atmosphere‐ice interactions is required to improve models, requiring year‐round observations address seasonally dependent biases. This work uses novel from MOSAiC expedition quantify responses fluxes radiative forcing over ice throughout a complete annual cycle. We identify two primary regimes flux response: an growth regime in winter and melt summer. In regime, changes impact upwelling longwave, sensible heat, subsurface heat fluxes, whereas primarily alter amount transmission because temperature fixed. These observed are used evaluate seven weather forecast models during regime. most do not match observations. Many also have biased downwelling longwave. One model (the Coupled Forecast System; CAFS) adequately captures mean winter. CAFS further evaluated against spanning full year, demonstrating sufficient agreement provide more generalized these SEB process relationships across Arctic.

Language: Английский

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