Isotopic signatures of snow, sea ice, and surface seawater in the central Arctic Ocean during the MOSAiC expedition

Elementa Science of the Anthropocene, Год журнала: 2024, Номер 12(1)

Опубликована: Янв. 1, 2024

The Arctic Ocean is an exceptional environment where hydrosphere, cryosphere, and atmosphere are closely interconnected. Changes in sea-ice extent thickness affect ocean currents, as well moisture heat exchange with the atmosphere. Energy water fluxes impact formation melting of sea ice snow cover. Here, we present a comprehensive statistical analysis stable isotopes various hydrological components central obtained during Multidisciplinary drifting Observatory for Study Climate (MOSAiC) expedition 2019–2020, including understudied winter. Our dataset comprises >2200 water, snow, samples. Snow had most depleted variable isotopic composition, δ18O (–16.3‰) increasing consistently from surface (–22.5‰) to bottom (–9.7‰) snowpack, suggesting that metamorphism wind-induced transport may overprint original precipitation isotope values. In Ocean, also help distinguish between different types, whether there meteoric contribution. composition salinity seawater indicated relative contributions freshwater sources: lower (approximately –3.0‰) salinities were observed near eastern Siberian shelves towards center Transpolar Drift due river discharge. Higher –1.5‰) associated Atlantic source when RV Polarstern crossed Gakkel Ridge into Nansen Basin. These changes driven mainly by shifts within carried across Ocean. highlights importance investigating fractionation effects, example, melting. A systematic full-year sampling strengthens our understanding cycle provides crucial insights interaction atmosphere, ice, their spatio-temporal variations MOSAiC.

Язык: Английский

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Observations of high-time-resolution and size-resolved aerosol chemical composition and microphysics in the central Arctic: implications for climate-relevant particle properties

Atmospheric chemistry and physics, Год журнала: 2025, Номер 25(4), С. 2207 - 2241

Опубликована: Фев. 19, 2025

Abstract. Aerosols play a critical role in the Arctic's radiative balance, influencing solar radiation and cloud formation. Limited observations central Arctic leave gaps understanding aerosol dynamics year-round, affecting model predictions of climate-relevant properties. Here, we present first annual high-time-resolution submicron chemical composition during Ocean 2018 (AO2018) 2019–2020 Multidisciplinary drifting Observatory for Study Climate (MOSAiC) expeditions. Seasonal variations mass concentrations were found to be driven by typical seasonal regimes resemble those pan-Arctic land-based stations. Organic aerosols dominated pristine summer, while anthropogenic sulfate prevailed autumn spring under haze conditions. Ammonium, which impacts acidity, was consistently less abundant, relative sulfate, compared lower latitudes Arctic. Cyclonic (storm) activity have significant influence on variability enhancing emissions from local sources transport remote aerosol. Local wind-generated particles contributed up 80 % (20 %) condensation nuclei population (spring). While analysis presented herein provides current baseline, will serve improve climate region, it also underscores importance integrating short-timescale processes, such as wind-driven blowing snow open leads/ocean simulations. This is particularly important, given decline mid-latitude increase ones.

Язык: Английский

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Formation and fate of freshwater on an ice floe in the Central Arctic

˜The œcryosphere, Год журнала: 2025, Номер 19(2), С. 619 - 644

Опубликована: Фев. 7, 2025

Abstract. The melt of snow and sea ice during the Arctic summer is a significant source relatively fresh meltwater. fate this freshwater, whether in surface ponds or thin layers underneath leads, impacts atmosphere–ice–ocean interactions their subsequent coupled evolution. Here, we combine analyses datasets from Multidisciplinary drifting Observatory for Study Climate (MOSAiC) expedition (June–July 2020) process study on formation freshwater floes Central Arctic. Our budget suggest that high fraction (58 %) derived melt. Additionally, contribution stored precipitation (snowmelt) outweighs by 5 times input situ (rain). magnitude rate local meltwater production are remarkably similar to those observed prior Surface Heat Budget Ocean (SHEBA) campaign, where cumulative totaled around 1 m both. A small (10 remains ponds, which higher more deformed second-year (SYI) compared first-year (FYI) later summer. Most drains laterally vertically, with vertical drainage enabling storage internally freshening brine channels. In upper ocean, can accumulate transient order 0.1 thick leads under ice. presence such substantially system reducing bottom allowing false growth; heat, nutrient, gas exchange; influencing ecosystem productivity. Regardless, majority inferred be ultimately incorporated into ocean (75 (14 %). Terms as annual could used future work diagnostics global climate models. For example, range values CESM2 model roughly encapsulate total production, while underestimated about 50 %, suggesting pond terms key investigation.

Язык: Английский

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Impacts of air fraction increase on Arctic sea ice density, freeboard, and thickness estimation during the melt season

˜The œcryosphere, Год журнала: 2025, Номер 19(3), С. 1259 - 1278

Опубликована: Март 17, 2025

Abstract. Arctic sea ice has undergone significant changes over the past 50 years. Modern large-scale estimates of thickness and volume come from satellite observations. However, these have limited accuracy, especially during melt season, making it difficult to compare state year year. Uncertainties in density lead high uncertainties retrieval its freeboard. During Multidisciplinary drifting Observatory for Study Climate (MOSAiC) expedition, we observed a first-year (FYI) freeboard increase 0.02 m, while decreased by 0.5 m season June–July 2020. Over same period, FYI 910 880 kg m−3, air fraction increased 1 % 6 %, due void expansion controlled internal melt. This substantially affected Due differences thermodynamic (such as salinity temperature), is less pronounced second-year (SYI) smaller impact on evolution SYI ridges. We validated our discrete measurements coring using co-located topography observations underwater sonar an airborne laser scanner. Despite decreasing thickness, similar counterintuitive increasing was entire 0.9 km2 MOSAiC floe, with stronger than saline SYI. The surrounding area experienced slightly lower 0.01 July 2020, despite comparable rates obtained mass balance buoys. defines rapid decrease density, complicates altimeters underlines importance considering algorithms.

Язык: Английский

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Low-level jets over the Arctic Ocean during MOSAiC

Elementa Science of the Anthropocene, Год журнала: 2022, Номер 10(1)

Опубликована: Янв. 1, 2022

We present an annual characterization of low-level jets (LLJs) over the Arctic Ocean using wind profiles from radiosondes launched during Multidisciplinary drifting Observatory for Study Climate expedition, October 2019 through September 2020. Our results show LLJs to be common throughout entire year, with a mean frequency occurrence more than 40%, typical height below 400 m, peaking at 120–180 and speed between 6 14 m s–1. Jet characteristics some seasonal variability: During winter freeze-up period, they are faster, average 55% speeds 8–16 s–1, while in summer transition have 46% 6–10 They similar all peak 120 180 m. The ERA5 reanalysis shows occurrence, but 75 high bias altitude, small, 0.28 slow speed. biases greater 130 is year. Examining full year whole Ocean, we find that depends strongly on both season distance sea-ice edge.

Язык: Английский

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