Currents, Fronts and Fine Structure in the Marginal Ice Zone of the Chukchi Sea

The article of record as published may be found at https://doi.org/10.1017/S0032247400021975Project MIZPAC (Marginal Ice Zone Pacific) was initiated in 1971 by the Arctic Submarine Laboratory, San Diego, California, to further the US Navy's understanding of problems associated with operating submarines under ice-covered oceans. Oceanographers from the Naval Postgraduate School took part in six summer cruises to the marginal sea ice zone (MIZ) of the shallow Chukchi Sea between 1971 and 1978 (Fig 1), providing the first detailed observations of the temperature-salinity structure within this dynamically active zone. Strong horizontal gradients of temperature and salinity marking boundaries between water masses (fronts), are widespread and well developed (Paquette and Bourke 1981). Where water masses intrude upon each other large-scale temperature inversions (anomalous increases in temperature with depth) often appear. Termed fine structure, these temperature anomalies include some of the largest observed anywhere in the world's oceans, sometimes exceeding 2°C over vertical distances of 5–10 m (Paquette and Bourke 1979). This article describes some of the fronts and fine structures observed in the Chukchi Sea, and shows how they develop within the general patterns of sea ice and circulation

Atlantic water on the Chukchi Shelf

An anomalously warm saline layer in the bottom of the shallow Chukchi Sea in August 1975 is believed due to a surge which drove water from the Atlantic Layer of the Arctic Ocean up onto the shelf. Two earlier occurrences of this kind of water in the Chukchi Sea have been identified in historical data.Submitted to: Director, Arctic Submarine Laboratory Naval Undersea Center, San Diego, CA.http://archive.org/details/atlanticwateronc00bourProject Order No. 00010N

Development of an Arctic Low Frequency Ambient Noise Model

LONG TERM GOALS: To develop a low frequency Arctic ambient noise model to predict extreme (loud /quiet) noise events due the presence or absence of storms.Award No. N0001497WR3009

USNS BARTLETT Cruise to the Greenland Sea in September 1989: Data Report

As a component of the Greenland Sea Project, a hydrographic cruise was conducted on board the USNS BARTLETT during September 1989 in the southern Greenland Sea to characterize the water mass structure and circulation features of the Jan Mayen Current (JMC). A total of 48 high-quality CTD stations were occupied to depths of 1000 m; five stations extended to 3000 m or more. Five north-south tending transects permitted tracking of the JMC by its low temperature (< 0°C) , low salinity near-surface core. The JMC could also be well defined from its warm, saline intermediate water properties. Deep stations made in the trough of the Jan Mayen Fracture Zone suggest that the interchange of deep and bottom water from the Greenland and Norwegian Seas via this trough is a slow diffusive process and not an active advective feature as previously thought.Arctic Submarine Laboratory, Naval Ocean Systems Center, San Diego, CA.http://archive.org/details/usnsbartlettcrui00bourO&MN, Direct Fundin

A study of the seasonal variation in temperature and salinity along the Oregon - Northern California coast

This study examines the seasonal variability in temperature and salinity of the nearshore waters off Oregon and Northern California. Specifically, temperature and salinity variations during summer and winter were ana1yzed from data gathered at shore stations along the coast and from hydrographic data collected within 25 nautical miles of shore. At each of five shore stations a modal cell technique was used to establish the temperature-salinity characteristics of the "normal" water type existing at each station during summer and winter. A classification scheme was employed to determine what local processes were influential in altering the "normal" T-S characteristics at each station. In summer mixing with Columbia River plume water was found to be the major modifying process along the Northern Oregon coast. Off Central and Southern Oregon local heating and mixing with water from the shelf/slope region were found to be most influential. In winter dilution due to precipitation and subsequent runoff is the major modifying factor along the entire coast except off Northern Oregon where mixing with shelf/slope waters is slightly more influential. The temperature and salinity structure of the near surface waters (< 200 meters) was examined for four latitudinal zones off the Oregon- Northern California coast. Within each zone profiles were constructed at 5, 15, and 25 nautical miles offshore. Surface waters are warmer and more saline in summer than in winter. Surface temperatures increase seaward in both seasons. Surface salinities increase seaward only during winter; in summer the increase is shoreward. Offshore gradients of temperature and salinity are one to two orders of magnitude greater than longshore gradients. A strong thermocline to 30 meters and a strong halocline to 75 meters is present in summer. In winter the water is isothermal to 50 meters while a strong halocline is present to 100 meters. Below these levels temperatures and salinities continue to slowly decrease and increase, respectively, until at 200 meters they become constant throughout the study area. Variability with distance from shore is significant only in summer and is constrained to the upper 150 meters of the water column

Collection and processing of shipboard ADCP velocities from the Barents Sea Polar Front Experiment

The Barents Sea Polar Front Experiment was a combined physical oceanography and acoustic tomography field study which took place from 6-26 August 1992. Both shipboard and moored data were collected in a 80 x 70 km experimental region on the south flank of Sptisbergen Bank about 60 km east of Bear Island. Of principal interest in this report are the data from an Acoustic Doppler Current Profier (ADCP) which was operated continuously during the experimental period as a part of the shipboard instrumentation aboard the USNS Barlett. The data from eight current meters deployed on three moorings in the experimental region are used to supplement the ADCP analysis. Preliminary results showed that velocities in the experimental region were dominated by semi-diurnal tides. The strong tidal oscilations dictated the use of a tide removal scheme to extract a steady flow component from the space-time grid of ADCP velocities. This report describes the configuration and operation of the ADCP, the space-time sampling grid on which the data were collected, the determination of absolute velocity from the ADCP measurements, and the application and results of a tide removal technique which allowed estimation of the sub-tidal flow.Funding was provided by the Office of Naval Research under Grant No. NOOOI4-90-J-1359

The Spitzer Survey of Interstellar Clouds in the Gould Belt. VI. The Auriga-California Molecular Cloud observed with IRAC and MIPS

We present observations of the Auriga-California Molecular Cloud (AMC) at 3.6, 4.5, 5.8, 8.0, 24, 70 and 160 micron observed with the IRAC and MIPS detectors as part of the Spitzer Gould Belt Legacy Survey. The total mapped areas are 2.5 sq-deg with IRAC and 10.47 sq-deg with MIPS. This giant molecular cloud is one of two in the nearby Gould Belt of star-forming regions, the other being the Orion A Molecular Cloud (OMC). We compare source counts, colors and magnitudes in our observed region to a subset of the SWIRE data that was processed through our pipeline. Using color-magnitude and color-color diagrams, we find evidence for a substantial population of 166 young stellar objects (YSOs) in the cloud, many of which were previously unknown. Most of this population is concentrated around the LkHalpha 101 cluster and the filament extending from it. We present a quantitative description of the degree of clustering and discuss the fraction of YSOs in the region with disks relative to an estimate of the diskless YSO population. Although the AMC is similar in mass, size and distance to the OMC, it is forming about 15 - 20 times fewer stars.Comment: (30 pages, 17 figures (2 multipage figures), accepted for publication in ApJ

Unrelated Helpers in a Primitively Eusocial Wasp: Is Helping Tailored Towards Direct Fitness?

The paper wasp Polistes dominulus is unique among the social insects in that nearly one-third of co-foundresses are completely unrelated to the dominant individual whose offspring they help to rear and yet reproductive skew is high. These unrelated subordinates stand to gain direct fitness through nest inheritance, raising the question of whether their behaviour is adaptively tailored towards maximizing inheritance prospects. Unusually, in this species, a wealth of theory and empirical data allows us to predict how unrelated subordinates should behave. Based on these predictions, here we compare helping in subordinates that are unrelated or related to the dominant wasp across an extensive range of field-based behavioural contexts. We find no differences in foraging effort, defense behaviour, aggression or inheritance rank between unrelated helpers and their related counterparts. Our study provides no evidence, across a number of behavioural scenarios, that the behaviour of unrelated subordinates is adaptively modified to promote direct fitness interests

The genomes of two key bumblebee species with primitive eusocial organization

Background: The shift from solitary to social behavior is one of the major evolutionary transitions. Primitively eusocial bumblebees are uniquely placed to illuminate the evolution of highly eusocial insect societies. Bumblebees are also invaluable natural and agricultural pollinators, and there is widespread concern over recent population declines in some species. High-quality genomic data will inform key aspects of bumblebee biology, including susceptibility to implicated population viability threats. Results: We report the high quality draft genome sequences of Bombus terrestris and Bombus impatiens, two ecologically dominant bumblebees and widely utilized study species. Comparing these new genomes to those of the highly eusocial honeybee Apis mellifera and other Hymenoptera, we identify deeply conserved similarities, as well as novelties key to the biology of these organisms. Some honeybee genome features thought to underpin advanced eusociality are also present in bumblebees, indicating an earlier evolution in the bee lineage. Xenobiotic detoxification and immune genes are similarly depauperate in bumblebees and honeybees, and multiple categories of genes linked to social organization, including development and behavior, show high conservation. Key differences identified include a bias in bumblebee chemoreception towards gustation from olfaction, and striking differences in microRNAs, potentially responsible for gene regulation underlying social and other traits. Conclusions: These two bumblebee genomes provide a foundation for post-genomic research on these key pollinators and insect societies. Overall, gene repertoires suggest that the route to advanced eusociality in bees was mediated by many small changes in many genes and processes, and not by notable expansion or depauperation