Wind waves may play an important role in the evolution of sea ice. That role is largely determined by how fast the ice layer dissipates the wave energy. The transition from a continuous layer of ice to a series of broken floes is expected to have a strong impact on the several attenuation processes. Here we explore the possible effects of basal friction, scattering, and dissipation within the ice layer. The ice is treated as a single layer that can be fractured in many floes. Dissipation associated with ice flexure is evaluated using an anelastic linear dissipation and a cubic inelastic viscous dissipation. Tests aiming to reproduce a Marginal Ice Zone are used to discuss the effects of each process separately. Attenuation is exponential for friction and scattering. Scattering produces an increase in the wave height near the ice edge and broadens the wave directional spectrum, especially for short-period waves. The nonlinear inelastic dissipation is larger for larger wave heights as long as the ice is not broken. These effects are combined in a realistic simulation of an ice break-up event observed south of Svalbard in 2010. The recorded rapid shift from a strong attenuation to little attenuation when the ice is broken is only reproduced when using a nonlinear dissipation that vanishes when the ice is broken. A preliminary pan-Arctic test of these different parameterizations suggests that inelastic dissipation alone is not enough and requires its combination with basal friction. Key Points:• A spectral wave model with effects of sea ice floe size is presented • Ice breakup is combined with three attenuations processes • Model wave heights for a break-up event reproduce observations in Svalbard apply to wide fields of pancakes that are found in the freezing season and but should rather be representative of waves interacting with solid ice pack. In these conditions, our goal is to explore plausible regimes of wave attenuation in the MIZ, given certain assumptions about wave-ice interaction processes.The different mechanisms that have been proposed to explain wave attenuation in the ice can be represented by source terms in the wave action equation describing the evolution of the wave field (Masson & LeBlond, 1989). The relative importance of the different mechanisms is still unknown in conditions encountered in the natural environment (Squire, 2007). Robin (1963) measured wave attenuation in the Weddel Sea but did not conclude on its possible source, mentioning anelastic dissipation (hysteresis) and basal friction as possible explanations. Wadhams (1973) hypothesized that wave could be dissipated by secondary creep, namely, the inelastic dissipation of waves due to the ice flexure, with a strain rate proportional to the cube of the stress, following the flow law used by Glen (1955) for very slow glacier motions. The work done during and after MIZEX emphasized scattering, that is, multiple reflections of waves by floes, as the dominant source of wave attenuation (Kohout & Meylan, 2008;Kohout et al., 2014;Montiel et...

Funding informationFonds Québécois de la recherche sur la nature et les technologies; Québec Ministry of Public Security Coastlines along the St. Lawrence Estuary and Gulf, Eastern Canada, are under increasing risk of flooding due to sea level rise and sea ice shrinking. Efficient and validated regional-scale coastal flood mapping approaches that include storm surges and waves are hence required to better prepare for the increased hazard. This paper compares and validates two different flood mapping methods: numerical flood simulations using XBeach and bathtub mapping based on total water levels, forced with multihazard scenarios of compound wave and water level events. XBeach is validated with hydrodynamic measurements. Simulations of a historical storm event are performed and validated against observed flood data over ã 25 km long coastline using multiple fit metrics. XBeach and the bathtub method correctly predict flooded areas (66 and 78%, respectively), but the latter overpredicts the flood extent by 36%. XBeach is a slightly more robust flood mapping approach with a fit of 51% against 48% for the bathtub maps. Deeper floodwater by~0.5 m is expected with the bathtub approach, and more buildings are vulnerable to a 100-year flood level. For coastal management at regional-scale, despite similar flood extents with both flood mapping approaches, results suggest that numerical simulati on with XBeach outperforms bathtub flood mapping.

Abstract. The Green Edge initiative was developed to investigate the processes controlling the primary productivity and fate of organic matter produced during the Arctic phytoplankton spring bloom (PSB) and to determine its role in the ecosystem. Two field campaigns were conducted in 2015 and 2016 at an ice camp located on landfast sea ice southeast of Qikiqtarjuaq Island in Baffin Bay (67.4797∘ N, 63.7895∘ W). During both expeditions, a large suite of physical, chemical and biological variables was measured beneath a consolidated sea-ice cover from the surface to the bottom (at 360 m depth) to better understand the factors driving the PSB. Key variables, such as conservative temperature, absolute salinity, radiance, irradiance, nutrient concentrations, chlorophyll a concentration, bacteria, phytoplankton and zooplankton abundance and taxonomy, and carbon stocks and fluxes were routinely measured at the ice camp. Meteorological and snow-relevant variables were also monitored. Here, we present the results of a joint effort to tidy and standardize the collected datasets, which will facilitate their reuse in other Arctic studies. The dataset is available at https://doi.org/10.17882/59892 (Massicotte et al., 2019a).

The near-surface temperature structure in the southeastern Beaufort Sea is shown to have been largely dependent on frontal dynamics in spring 2004, which may be typical for the region. Easterly wind events generated coastal upwelling along the Cap Bathurst peninsula; a recurring event in that area. Further west, a large mesoscale anticyclone simultaneously developed and subsequently controlled the sea-surface circulation in the central Amundsen Gulf. Sharp temperature and density fronts were created at the surface at both eastern and western ends of the domain. Sampling north of Cape Bathurst and Cape Parry showed evidence of frontal intensification. Frontal features were detected near the 50-200 m isobaths, at the mouth of the gulf, where density-compensated near-surface intrusions driven by agesotrophic vertical circulation were identified. These warm water tongues intruded into the outcropping isopycnal layers, which dipped down between 5 and 25 m over the Mackenzie Shelf. They then crossed the density surfaces with an inverse slope consistent with N/f as predicted for quasi-geostrophic flows. The front event ended prior to the breakup of the landfast-ice bridge in late June with sea-surface temperature undergoing quick and widespread changes throughout the Amundsen Gulf.

Abstract. The Green Edge initiative was developed to investigate the processes controlling the primary productivity and the fate of organic matter produced during the Arctic phytoplankton spring bloom (PSB) and to determine its role in the ecosystem. Two field campaigns were conducted in 2015 and 2016 at an ice camp located on landfast sea ice southeast of Qikiqtarjuaq Island in Baffin Bay (67.4797N, 63.7895W). During both expeditions, a large suite of physical, chemical and biological variables was measured beneath a consolidated sea ice cover from the surface to the bottom at 360 m depth to better understand the factors driving the PSB. Key variables such as temperature, salinity, radiance, irradiance, nutrient concentrations, chlorophyll-a concentration, bacteria, phytoplankton and zooplankton abundance and taxonomy, carbon stocks and fluxes were routinely measured at the ice camp. Here, we present the results of a joint effort to tidy and standardize the collected data sets that will facilitate their reuse in other Arctic studies. The dataset is available at http://www.seanoe.org/data/00487/59892/ (Massicotte et al., 2019a).