ABSTRACT 2017-081 Responders need to choose among oil spill response options to combat spills in ice covered waters as effectively as possible. A decision to apply dispersants in remote ice covered waters requires an estimation of whether or not the oil will initially disperse and then remain dispersed. A concern is that an effectively dispersed plume of oil will not remain dispersed under ice because the mixing energy required is insufficient. We are advancing the predictive capability to determine whether small oil droplets will rise in the calmer, more stable conditions that can occur in ice covered waters. The results will be presented as lookup tables that can be used to assess whether or not oil has been successfully dispersed in ice covered waters. Ice covered waters can have very low vertical turbulence (mixing) energy, so smaller droplets may rise to the surface in ice covered waters than in open water at lower latitudes. Laboratory studies with oil droplets and field experiments to measure the turbulence directly under ice are being used to provide input and validation data to numerically simulate an oil spill in ice. We assumed that oil slicks were effectively dispersed to form plumes in the water column. Dispersion was assumed to be from natural mixing energy or forced by applying the propeller wash from vessels. The numerical simulations will be performed to determine if these dispersed plumes could significantly resurface. The International Oil and Gas Producers (IOGP) funded the Joint Industry Project (JIP) “Fate of Dispersed Oil Under Ice”. Sintef led two field campaigns (2015 and 2016) with fast ice (ice attached to land) in Van Miljenfjorden in Svalbard. These data for realistic water currents and mixing energy (turbulence) were used in model development. In the second field experiment, dye was released and followed under the ice in order to measure dilution of the dye, as a check on our model. Neap tide periods were targeted in order to look at low mixing energy conditions. At the Plymouth University mesoscale laboratory, studies in a 30 m flume allowed oil droplets of known size to be released in water flowing under synthetic ice under controlled water velocity and under ice roughness conditions. In addition, an analytical model is being developed to estimate the magnitude and dissipation rate of prop wash turbulence. This was necessary to give the time zero basis for estimating how quickly droplets produced by prop wash would rise to the surface. Size classes of oil droplets that do not rise in low vertical turbulence will certainly not rise in higher turbulence. This will allow future research to target larger oil droplet size classes in the Marginal Ice Zone (MIZ). This project was led by SINTEF (Norway) with participation by McPhee Research (USA), University of Plymouth (UK), and Ben Gurion University (Israel).

We report observations of heat and momentum fluxes measured in the ice-ocean boundary layer from four drift stations between January and June 2015, covering from the typical Arctic basin conditions in the Nansen Basin to energetic spots of interaction with the warm Atlantic Water branches near the Yermak Plateau and over the North Spitsbergen slope. A wide range of oceanic turbulent heat flux values are observed, reflecting the variations in space and time over the five month duration of the experiment. Oceanic heat flux is weakly positive in winter over the Nansen Basin during quiescent conditions, increasing by an order of magnitude during storm events. An event of local upwelling and mixing in the winter-time Nansen basin highlights the importance of individual events. Spring-time drift is confined to the Yermak Plateau and its slopes, where vertical mixing is enhanced. Wind events cause an approximate doubling of oceanic heat fluxes compared to calm periods. In June, melting conditions near the ice edge lead to heat fluxes of O(100 W m−2). The combination of wind forcing with shallow Atlantic Water layer and proximity to open waters leads to maximum heat fluxes reaching 367 W m−2, concurrent with rapid melting. Observed ocean-to-ice heat fluxes agree well with those estimated from a bulk parameterization except when accumulated freshwater from sea ice melt in spring probably causes the bulk formula to overestimate the oceanic heat flux. This article is protected by copyright. All rights reserved.

Abstract. Late winter measurements of turbulent quantities in tidally modulated flow under land-fast sea ice near the Erebus Glacier Tongue, McMurdo Sound, Antarctica, identified processes that influence growth at the interface of an ice surface in contact with supercooled seawater. The data show that turbulent heat exchange at the ocean–ice boundary is characterized by the product of friction velocity and (negative) water temperature departure from freezing, analogous to similar results for moderate melting rates in seawater above freezing. Platelet ice growth appears to increase the hydraulic roughness (drag) of fast ice compared with undeformed fast ice without platelets. Platelet growth in supercooled water under thick ice appears to be rate-limited by turbulent heat transfer and that this is a significant factor to be considered in mass transfer at the underside of ice shelves and sea ice in the vicinity of ice shelves.

[1] Measurements near the edge of fast ice in Freemansundet, Svalbard, reveal mixing processes associated with tidal advection of a sharp front in salinity, including possible supercooling induced by double diffusion in a fully turbulent water column. The front translated back and forth with the semidiurnal tide between an area of mobile (drifting) ice in Storfjorden proper, and the narrow sound covered by fast ice. Water on each side of the front was near its salinity-determined freezing temperature. Instruments deployed about 400 m into the sound from the fast ice edge measured current, temperature, conductivity, and turbulence quantities through several tidal cycles. Turbulence data illustrate that as the steep horizontal salinity (density) gradient advected past the measurement site, vertical shear near the fast-ice base induced marked flood/ebb asymmetry in turbulent mixing. As fresher water entered the sound on the flood phase, inward transport of denser water near the upper boundary was retarded, leading to statically unstable conditions and enhanced turbulence. The opposite occurred during ebb tide, as denser water underran lighter. Transient episodes of supercooling accompanied frontal passage on both flood and ebb phases. The most likely explanation for a zone of supercooled water within the strongly mixed frontal region is that during mixing of fresher, slightly warmer (but still at freezing) water from outside with saltier, colder water in the sound, the former constituent lost heat faster than gaining salt. This interpretation (differing turbulent diffusivities for heat and salt) challenges strict application of Reynolds analogy for highly turbulent shear flow.

[1] Hydrographical measurements from the Storfjorden polynya document the presence of an abrupt front in near-freezing water dividing saline water recently created by a polynya event, from less saline water originating further south. This event occurred days before the survey with estimated heat flux ∼400 W m−2 over the polynya. Brine-enriched shelf water (BSW) is observed downslope toward deeper parts of Storfjorden, and BSW from earlier polynya events overflows the sill. Current measurements from a nearby sound, Freemansundet, document tidal currents exceeding 80 cm s−1 that displaced the front back and forth beneath the measurement site on fast ice ∼400 m from the polynya edge. Front displacement of ∼12 km is documented and mainly due to the M2 component superimposed on a mean residual current of 0.28 m s−1 into the sound induced by southerly wind during the survey. Complex topography imposes baroclinic tidal currents with strong vertical shear in the fast ice-covered sound, and with significant cross-channel flow. Supercooling events indicated in the hydrographical time series, and likely enhanced frazil ice production, are associated with double-diffusive turbulent mixing when the salinity front passes. In this way, these measurements indicate a novel ice production process along the edge of tidally induced latent heat polynyas where salinity fronts are generated. Turbulence increases (decreases) during flood (ebb) due to the destabilization (stabilization) of the water column when the salinity front passes the measurement site. Double-diffusive turbulent mixing related to tidal advection of salinity front below fast ice is pursued in a companion paper.

Abstract Continuous sampling of upper-ocean hydrographic data in the Canada Basin from various sources spanning from 2003 through 2011 provides an unprecedented opportunity to observe changes occurring in a major feature of the Arctic Ocean. In a 112-km-radius circle situated near the center of the traditional Beaufort Gyre, geopotential height referenced to 400 dbar increased by about 0.3 gpm from 2003 to 2011, and by the end of the period had increased by about 65% from the climatological value. Near the edges of the domain considered, the anomalies in dynamic height are much smaller, indicating steeper gradients. A rough dynamic topography constructed from profiles collected between 2008 and 2011 shows the center of the gyre to have shifted south by about 2° in latitude, along the 150°W meridian. Geostrophic currents are much stronger on the periphery of the gyre, reaching amplitudes 5–6 times higher than climatological values at grid points just offshore from the Beaufort and Chukchi shelf slopes. Estimates of residual buoy drift velocity after removing the expected wind-driven component are consistent with surface geostrophic currents calculated from hydrographic data. A three-decade time series of integrated ocean surface stress curl during late summer near the center of the Beaufort Gyre shows a large increase in downward Ekman pumping on decadal scales, emphasizing the importance of atmospheric forcing in the recent accumulation of freshwater in the Canada Basin. Geostrophic current intensification appears to have played a significant role in the recent disappearance of old ice in the Canada Basin.

Electric grid energy storage value. System-level asset focus for mechanical and electrochemical energy storage. Analysis questions for power system planning, operations, and customer-side solutions.

Abstract Variation of ice/ocean drag (momentum exchange) is an important yet often overlooked aspect of pack ice modeling. It is commonly parameterized as proportional to the square of the velocity difference between the ice and the undisturbed ocean, often with a constant angle offset to account for rotational effects in the ice–ocean boundary layer. This approach is critiqued in light of extensive observations that have revealed the underlying turbulence scales governing momentum exchange within the IOBL. Fluid dynamical similarity implied by these scales provides a framework for addressing several factors that affect the drag relationship, including variation in ice roughness, relative drift speed, buoyancy flux at the ice/ocean interface, and stratification in the upper ocean. These are examined and discussed in light of recent changes in the Arctic ice pack. The drag law is formulated in terms of dimensionless surface velocity, which in its simplest form is called Rossby similarity, and accounts explicitly for variation in undersurface hydraulic roughness, z 0 . A generalization that includes interfacial buoyancy flux is also described and illustrated, and the impact of near surface ocean stratification is discussed. Estimates of z 0 based on underice measurements vary widely; by a combination of observations and simple IOBL modeling, an attempt is made to reduce these to a manageable set associated with distinct ice types.

As part of our efforts to develop agents for CNS diseases, we have been focused on the 5-HT(6) receptor in order to identify potent and selective ligands for cognitive enhancement. Herein we report the identification of a novel series of 5-piperazinyl-3-sulfonylindazoles as potent and selective 5-HT(6) antagonists. The synthesis, SAR, and pharmacokinetic and pharmacological activities of some of the compounds including 3-(naphthalen-1-ylsulfonyl)-5-(piperazin-1-yl)-1H-indazole (WAY-255315 or SAM-315) will be described.

We introduce a new optimal design for dose finding with a continuous efficacy endpoint. This design is studied in the context of a flexible model for the mean of the dose-response. The design incorporates aspects of both D- and c-optimality and can be used when the study goals under consideration include dose-response estimation, followed by identification of the target dose. Different optimality criteria are considered. Simulations are shown with results comparing our adaptive design to the fixed allocation (without adaptations). We show that both the estimation of dose-response and identification of the minimum effective dose are improved using our design.