Peter Winsor

The ice cover of the Arctic Ocean is considered to be a sensitive indicator of global climate change. Recent research, using submarine-based observations, suggests that the Arctic ice cover was thinner in the 1990s compared to an earlier period (1958-1979), and that it continued to decrease in thickness in the 1990s. Here I analyze subsurface ice thickness (draft) of Arctic sea ice from six submarine cruises from 1991 to 1997. This extensive data set shows that there was no trend towards a thinning ice cover during the 1990s. Data from the North Pole shows a slight increase in mean ice thickness, whereas the Beaufort Sea shows a small decrease, none of which are significant. Transects between the two areas from 76°N to 90°N also show near constant ice thicknesses, with a general spatial decrease from the Pole towards the Beaufort Sea. Combining the present results with those of an earlier study, I conclude that the mean ice thickness has remained on a near-constant level around the North Pole from 1986 to 1997.

ABSTRACT Understanding the fate and influence of glacial meltwater in heavily ice-covered fjord systems has proven difficult because previous measurement platforms were con­strained to deeper water to keep instrumentation safe from drifting icebergs. Now, using novel, satellite-tracked devices that can with­ stand multiple collisions with ice blocks (see Figure 1) without incurring much damage, scientists have obtained new and detailed data about the role of Greenland Ice Sheet meltwater and its trajectories through God­thåbsfjord in western Greenland.

ABSTRACT This study investigates the applicability of the optimal interpolation (OI) method proposed by Kim et al. for estimating ocean surface currents from high-frequency radar (HFR) in the northeastern Chukchi Sea, where HFR siting is dictated by power availability rather than optimal locations. Although the CU technique improves data coverage when compared to the conventional unweighted least squares fit (UWLS) method, biased solutions can emerge. The quality of the HFR velocity estimates derived by OI is controlled by three factors: 1) the number of available incorporating radials (AR), 2) the ratio of the incorporating radials from multiple contributing site locations [ratio of overlapping radial velocities (ROR) or radar geometry], and 3) the positive definiteness [condition number (CN)] of the correlation matrix. Operationally, ROR does not require knowledge of the angle covariance matrix used to compute the geometric dilution of precision (GDOP) in the UWLS method and can be computed before site selection to optimize coverage or after data processing to assess data quality when applying the OI method. The Kim et al. method is extended to examine sensitivities to data gaps in the radial distribution and the effects on OI estimates.

ABSTRACT Most regional ocean models that use discharge as part of the forcing use relatively coarse river discharge data sets (1°, or ∼110 km) compared to the model resolution (typically 1/4° or less), and do not account for seasonal changes in river water temperature. We introduce a new climatological data set of river discharge and river water temperature with 1/6° grid spacing over the Arctic region (Arctic River Discharge and Temperature; ARDAT), incorporating observations from 30 Arctic rivers. The annual mean discharge for all rivers in ARDAT is 2817 ± 330 km3 yr-1. River water temperatures range between 0 °C in winter to 14.0 - 17.6 °C in July, leading to a long-term mean monthly heat flux from all rivers of 3.2 ± 0.6 TW, of which 31% is supplied by Alaskan rivers and 69% is supplied by Eurasian rivers. This riverine heat flux is equivalent to 44% of the estimated ocean heat flux associated with the Bering Strait throughflow, but during the spring freshet can be ∼10 times as large, suggesting that heat flux associated with Arctic rivers is an important component of the Arctic heat budget on seasonal time scales.

ABSTRACT The concentration of 129I is measured in seawater along a transect from the North Pole to the Norwegian Sea. The goal is to elucidate transport paths of discharged radioactivity from Western Europe to the Arctic Ocean, which is closely related to ocean circulation in the region. This investigation continues the previously reported study of 129I concentration levels in this area [1] and will give additional information about the spatial and temporal distribution of the discharges from Sellafield and La Hague reprocessing facilities in the Northern Hemisphere. Surface seawater and depth profiles down to 3900 m were collected by the Swedish Arctic Ocean 2001 ice-breaker expedition and analyzed at the Uppsala AMS facility. Most of the samples are prepared according to a standard preparation procedure for seawater [2] (about 2 mg carrier per 200 ml of seawater) and in addition a carrier-free approach is tested. [1] N. Buraglio, A. Aldahan, G. Possnert, Distribution and inventory of 129I in the central Arctic Ocean, Geophysical Research Letters, Vol. 26, No. 8 (1999) 1011-1014 [2] N. Buraglio, A. Aldahan, G. Possnert, 129I measurements at the Uppsala tandem accelerator, Nuclear Instruments and Methods in Physics Research B 161-163 (2000) 240-244

ABSTRACT Hydrographic observations from four icebreaker expeditions to the Arctic Ocean between 1991 and 2001 show evidence of changes in the deep waters of the Arctic Ocean. The deepest waters show 300-1000 m thick homogenous bottom layers, characterized by slightly warmer temperatures compared to ambient, overlying water masses, indicating that they may have formed by convection induced by geothermal heat supplied from Earth's interior. The layers are present in the central parts of the deep basins, away from continental slopes and ocean ridges. The observations also suggest relatively large changes in the deep waters of the Amundsen Basin between 1991 and 2001, with warmer water being present in 2001 over the entire deep-water column.

Present knowledge of the circulation of the mid-depth and deep layers of the Arctic Ocean is limited, especially so from direct current observations. This is in contrast to the circulation of sea ice and the surface layer of the Arctic, where satellite observations together with ice buoys have been able to monitor the circulation since the late 1970s. This lack

ABSTRACT The climate of the Baltic Sea has been investigated for the last two hundred years using the annual mean of instrumental data of air temperature, sea level, NAO and sea ice. The objective of the study is to investigate how to define and analyse climate variations on relevant climatological time scales that are valid for all data sets. By computing normalized variance for the different data sets we were able to deduce on which time scale most of the variance occurs. This time scale serves as a measure of a climatological period with very low inherent variance. Each dataset is then divided into such subsets and some basic statistics are computed. A seasonal index was constructed from the air temperature to serve as a measurement of the annual temperature amplitude. This index exposed a shift in the late 19th century indicating a change in the seasonal cycle and hereby the climate during this period. This shift has been reported in other studies, and is probably due to a change in the large-scale atmospheric circulation. Although the mean values of the parameters studied appear to incorporate a trend towards a warmer climate in the 20th century, the study of the minimum and maximum values shows the occurrence of extreme values in both centuries.

... 767 Evaluating the Use of Register Queues in Software Pipelined Loops GS Tyson, M. Smelyanskiy, and ES Davidson ... IEEE COMPUTER SOCIETY Officers BENJAMIN W. WAH, President CARL CHANG, First VP, Educational Activities STEVE DIAMOND, Treasurer ...

ABSTRACT Persistently poor weather in the Arctic makes traditional marine mammal research from aircraft and ships difficult, yet collecting information on marine mammal distri- bution and habitat utilization is vital for understanding the impact of climate change on Arctic ecosystems. Moreover, as industrial use of the Arctic increases with the expan- sion of the open-water summer season, there is an urgent need to monitor the effects of noise from oil and gas exploration and commercial shipping on marine mammals. During September 2013, we deployed a single Slocum glider equipped with a digital acoustic monitoring (DMON) instrument to record and process in situ low-frequency (<5 kHz) audio to characterize marine mammal occurrence and habitat as well as am- bient noise in the Chukchi Sea off the northwest coast of Alaska, USA. The DMON was programmed with the low-frequency detection and classification system (LFDCS) to autonomously detect and classify sounds of a variety of Arctic and sub-Arctic marine mammal species. The DMON/LFDCS reported regularly in near real time via Iridium satellite detailed detection data, summary classification information, and spectra of background noise. The spatial distributions of bowhead whale, bearded seal, and wal- rus call rates were correlated with surface salinity measured by the glider. Bowhead whale and walrus call rates were strongly associated with a warm and salty water mass of Bering Sea origin. With a passive acoustic capability that allows both archival re- cording and near real-time reporting, we envision ocean gliders will become a standard tool for marine mammal and ocean noise research and monitoring in the Arctic. Keywords: autonomous vehicle, marine mammals, ocean noise, habitat, Chukchi Sea

ABSTRACT We present high-resolution space-time dependent observations of circulation and stratification features in the Chukchi Sea, Arctic Ocean from an observing system consisting of AUV gliders, HF radars, drifters, and sub-surface moorings. These unique high-latitude observations show a more complex, dynamic and high-energy ocean environment than previously reported in the Arctic. We also present examples of imminent technology needs for high-latitude areas.

ABSTRACT Abstract We are conducting a multi-platform field study to investigate the impact of local physical processes on Adélie penguin foraging ecology in the vicinity of Palmer Deep off Anvers Island, Western Antarctic Peninsula (WAP). Guided by real-time remotely sensed surface current measurements of convergence derived from a network of high-frequency radars (HFRs), we adaptively sample the distribution and biomass of phytoplankton and Antarctic krill, which influence Adélie penguin foraging ecology, to understand how local oceanographic processes structure the ecosystem. The recent application of ocean observing and animal telemetry technology over Palmer Deep has led to new understanding and many new questions related to polar ecosystem processes. The HFR coastal surface current mapping network is uniquely equipped to resolve local circulation patterns over Palmer Deep. The surface current measurements enable identification of regions of convergence and divergence in real time. Guided by these maps, our field study adaptively samples the measured convergence and divergence zones within the context of semi-diurnal and diurnal mixed tidal regimes. The in situ sampling includes (a) a mooring deployment, (b) multiple underwater glider deployments, (c) small boat acoustic surveys of Antarctic krill, and (d) penguin ARGOS-linked satellite telemetry and temperature-depth recorders (TDRs). The combination of real-time surface convergence maps with adaptive in situ sampling introduces HFR to the Antarctic in a way that allows us to rigorously and efficiently test the influence of local tidal processes on top predator foraging ecology.

ABSTRACT A model describing wind-driven coastal polynyas and the effects of brine rejection on the local salinity field is compared to remote sensing data from ERS-1/2 and SSM/I. The ERS SAR browse image product is applied for animating the temporal and spatial extent of the polynyas and thereafter the precision image (PRI) product for high resolution studies of the identified polynyas. Daily averaged SSM/I sea ice concentration data derived from the NASA Team and the bootstrap algorithms are applied as secondary data for polynya identification. A comparison of these algorithms to the high resolution SAR shows significant differences. The ERS SAR images are shown to be important for verifying the numerical model and for understanding the polynyas' development processes while the SSM/I has significantly less correlation with the numerical model and the SAR

General dynamical features of East Greenland Current (EGC) are synthesized from a survey conducted by the icebreaker Oden during the Swedish Arctic Ocean Expedition 2002. The data includes hydrography and ADCP observations in eight transects of the EGC, from the Fram Strait in the north to the Denmark Strait in the south. The survey reveals a strong confinement of the low-saline polar water in the EGC to the continental slope/shelf --- a feature of relevance for the overall stability of the thermohaline circulation in the Arctic Ocean. The southward transport of liquid freshwater in the EGC was found to vary dramatically between transects: from peak values on the order of 0.06 Sverdrup to virtually zero. The dynamical origin of the observed alongstream pulsations in freshwater transport is briefly discussed from a theoretical standpoint, emphasizing the potential for freshwater leakage into the deep-water producing areas in the Greenland Sea.

Variation in the concentrations of iodine-129 (129I, T1/2=15.7 Myr), a low-level radioactive component of nuclear fuel waste, is documented in surface waters and depth profiles collected during 2001 along a transect from the Norwegian Coastal Current to the North Pole. The surface waters near the Norwegian coast are found to have 20 times higher 129I concentration than the surface waters of the Arctic Ocean. The depth profiles of 129I taken in the Arctic Ocean reveal a sharp decline in the concentration to a depth of about 300-500 m followed by a weaker gradient extending down to the bottom. A twofold increase in the 129I concentration is observed in the upper 1000 m since 1996. Based on known estimates of marine transient time from the release sources (the nuclear reprocessing facilities at La Hague, France, and Sellafield, UK), a doubling in the 129I inventory of the top 1000 m of the Arctic Ocean is expected to occur between the years 2001 and 2006. As 129I of polar mixed layer and Atlantic layer of the Arctic Ocean is ventilated by the East Greenland Current into the Nordic Seas and North Atlantic Ocean, further dispersal and increase of the isotope concentration in these regions will be encountered in the near future.