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The amount of snow on Arctic sea ice impacts the ice mass budget. Wind redistribution of snow into open water in leads is hypothesized to cause significant wintertime snow loss. However, there are no direct measurements of snow loss into Arctic leads. We measured the snow lost in four leads in the Central Arctic in winter 2020. We find, contrary to expectations, that under typical winter conditions, minimal snow was lost into leads. However, during a cyclone that delivered warm air temperatures, high winds, and snowfall, 35.0 ± 1.1 cm snow water equivalent (SWE) was lost into a lead (per unit lead area). This corresponded to a removal of 0.7–1.1 cm SWE from the entire surface—∼6%–10% of this site's annual snow precipitation. Warm air temperatures, which increase the length of time that wintertime leads remain unfrozen, may be an underappreciated factor in snow loss into leads. The amount of snow on Arctic sea ice impacts how quickly the ice grows in the winter and melts in the summer. Cracks in the ice, known as leads, expose ocean water that snow can be blown into, reducing the amount of snow on the ice and thus impacting ice growth and melt. We found that in typical wintertime conditions, very little snow is blown into leads. However, if there is fresh snowfall, it is uncommonly warm and it is very windy at the same time when leads are forming, a large amount of snow can be blown into the ocean. Accounting for the impacts of air temperature on this process will enable scientists to better understand how much snow is on Arctic sea ice, and hence how quickly the ice grows in the winter and melts in the summer, and how this might change in a future, warmer, Arctic. Minimal snow was lost into leads in observations of three cases in typical wintertime, cold, moderately windy conditions on Arctic sea iceIn an atmospheric advection event with air temperature above −10°C, high wind, and fresh snowfall, most recent snowfall was lost into leadsWarm air temperatures increase the duration of unfrozen water in leads, which may be an underappreciated factor in snow loss into leads Minimal snow was lost into leads in observations of three cases in typical wintertime, cold, moderately windy conditions on Arctic sea ice In an atmospheric advection event with air temperature above −10°C, high wind, and fresh snowfall, most recent snowfall was lost into leads Warm air temperatures increase the duration of unfrozen water in leads, which may be an underappreciated factor in snow loss into leads

The “surface scattering layer” (SSL) is the highly‐scattering, coarse‐grained ice layer that forms on the surface of melting, drained sea ice during spring and summer. Ice of sufficient thickness with an SSL has an observed persistent broadband albedo of ∼0.65, resulting in a strong influence on the regional solar partitioning. Experiments during the Multidisciplinary drifting Observatory for the Study of the Arctic Climate expedition showed that the SSL re‐forms in approximately 1 day following manual removal. Coincident spectral albedo measurements provide insight into the SSL evolution, where albedo increased on sunny days with higher solar insolation. Comparison with experiments in radiative transfer and global climate models show that the sea ice albedo is greatly impacted by the SSL thickness. The presence of SSL is a significant component of the ice‐albedo feedback, with an albedo impact of the same order as melt ponds. Changes in SSL and implications for Arctic sea ice within a warming climate are uncertain. During the summer melt season, the surface of Arctic sea ice generally transforms into a crumbly, snow‐like layer that is known as the “surface scattering layer” (SSL). As the name implies, it is highly‐scattering, resulting in a high reflectivity where typically around 65% of incoming solar energy is reflected. However, this value has been observed to be lower, particularly when the layer is relatively thin, and there is very little known about what controls its variability. We completed experiments on summer sea ice to observe what happens when the layer is completely removed. We completed similar experiments in models, where we were able to simulate the expected reflectivity over a range of layer thicknesses, and then see what the expected impact on Arctic sea ice would be with complete removal. We find that removal of this layer dramatically reduces sea ice albedo and Arctic sea ice volume. The SSL is an under‐appreciated feature of Arctic sea ice, and more work to understand its variability in a warming Arctic is needed. Surface scattering layer (SSL) is a persistent feature of bare, melting sea ice that is central to the sea ice‐albedo feedbackObservations and modeling both show sea ice albedo sensitivity to SSL thicknessModels represent the optical properties of the SSL layer as a function of ice thickness only, but these properties also vary with morphology Surface scattering layer (SSL) is a persistent feature of bare, melting sea ice that is central to the sea ice‐albedo feedback Observations and modeling both show sea ice albedo sensitivity to SSL thickness Models represent the optical properties of the SSL layer as a function of ice thickness only, but these properties also vary with morphology