Bedload transport is an important mechanism for sediment flux in the nearshore. Yet few studies examine the relationship between bedform evolution and net sediment transport. Our work contributes concurrent observations of bedform mobility and bedload transport in response to wave dominant, current dominant, and combined wave‐current flows in the nearshore. Bedload sediment flux from migrating bedforms during combined wave‐current conditions accounted for at least 20% more bedload transport when compared with wave dominant flows and at least 80% more than current‐dominant flows. Bedforms were observed to transport the most sediment during periods with strong currents, with high‐energy skewed waves, and while bedform orientation and transport direction were aligned. Regardless of flow type, bedform migration rates were directly proportional to the total kinetic energy contained in the flow field. Eleven bedload transport models formulated to be used in combined flows (both shear and energetics based) were compared with sediment flux estimated from measured bedform migration. An energetics based sediment transport model was most representative for our data.

To predict ecosystem change in the Arctic Ocean, understanding Arctic phytoplankton phenology is essential. We develop a marine ecosystem model focusing on phytoplankton dynamics and the competition for multiple resources based on knowledge from in situ data obtained in the Chukchi Sea. The model is designed to include the unique ecological characteristics of the Arctic Ocean. To the best of our knowledge, this is the first model successfully simulating the current paradigm for Arctic phytoplankton phenology, including both under‐ice blooms and succession of phytoplankton groups. Sensitivity experiments show that the dominance of diatoms can be sustained by lateral transport of a high‐silicate water mass (Pacific Winter Water). Experiments for future scenarios show that sea ice retreat drives a decrease in large diatoms and an increase in the other relatively small non‐diatom groups. These results suggest that dominant phytoplankton groups can be shifted from diatoms to non‐diatoms under ongoing Arctic Ocean sea ice retreat.

Field observations of oscillating currents in the surfzone of a natural beach show significant vertical structure in energy, phase, and rotation at low frequencies around 0.005 Hz, where most of the energy is associated with vorticity motions. Energy levels in the cross-shore component of the flow seaward of the sandbar decay near the bottom. Shoreward of the bar crest, the flow decays nearly linearly over the water column. Conversely, a weaker alongshore component of the flow increases near the bottom seaward of the sandbar and is roughly depth-uniform inside the bar crest. Near this 0.005-Hz frequency band, the coherence between the uppermost and successive vertically separated sensors drops off quickly, with as much as a 70%–80% coherence drop over the water column (ranging from 2.5 to 4 m). The phase relative to the uppermost sensor shifts approximately linearly over depth, with as much as 50° phase lag at the bottom that can lag or lead the surface. Rotary coefficients also vary across the surfzone and are generally nonzero with rotational directions (cyclonic or anticyclonic) and orientation that depend on sensor position relative to the sandbar and alongshore current profile. The rotary coefficients are generally not uniform with depth and can change sign in the vertical. The observed behavior is qualitatively predicted by boundary layer theory (discussed in the companion paper by Lippmann and Bowen). The nonuniform vertical structure has implications to the interpretation of field data and horizontal nearshore mixing.