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Articles 1 - 17 of 17
Full-Text Articles in Physical Sciences and Mathematics
A Case Study Of The 8 March 1999 Freezing Rain Event For North Platte, Nebraska, Shari Mutchler
A Case Study Of The 8 March 1999 Freezing Rain Event For North Platte, Nebraska, Shari Mutchler
United States Department of Commerce: Staff Publications
During the morning hours of 8 March 1999, freezing precipitation fell over portions of western Nebraska, including the communities of McCook, North Platte and Valentine between midnight and 10:00 A.M. CST. The freezing precipitation resulted in dangerous travel conditions, causing several automobile accidents, along with the delay and temporary closing of area public schools 8 March 1999. The freezing rain changed over to snow later the same morning.
A forecast for snow, rather than freezing precipitation, was issued by the local forecast office. The forecast issued was based predominately on numerical weather prediction guidance, and the observed temperature profile of …
Acoustic Detections Of Singing Humpback Whales In Deep Waters Off The British Isles, Russell Charif, Phillip Clapham, Christopher Clark
Acoustic Detections Of Singing Humpback Whales In Deep Waters Off The British Isles, Russell Charif, Phillip Clapham, Christopher Clark
United States Department of Commerce: Staff Publications
From October 1996 through September 1998, we used bottom-mounted hydrophone arrays to monitor deep-water areas north and west of the British Isles for songs of humpback whales (Megaptera novaeangliae). Singing humpbacks were consistently detected between October and March from the Shetland- Faroe Islands south to waters west of the English Channel. Temporal and geographic patterns of song detections, and movements of individually tracked whales, exhibited a southwesterly trend over this period, but with no corresponding northward trend between April and September. These results, together with a review of historical data from this area, suggest that the offshore waters …
Movements And Population Structure Of Humpback Whales In The North Pacific, John Calambokidis, Gretchehn Steiger, Janice Straley, Louis Herman, Salvatore Cerchio, Dan Salden, Jorge Urban R., Jeff Jacobsen, Olga Von Ziegesar, Kenneth Balcomb, Christine Gabriele, Marilyn Dahlheim, Senzo Uchida, Graeme Ellis, Yukifumi Miyamura, Paloma Ladron De Guevara P., Manami Yamaguchi, Fumihiko Sato, Sally Mizroch, Lisa Schlender, Jay Barlow, Terrance Quinn Ii
Movements And Population Structure Of Humpback Whales In The North Pacific, John Calambokidis, Gretchehn Steiger, Janice Straley, Louis Herman, Salvatore Cerchio, Dan Salden, Jorge Urban R., Jeff Jacobsen, Olga Von Ziegesar, Kenneth Balcomb, Christine Gabriele, Marilyn Dahlheim, Senzo Uchida, Graeme Ellis, Yukifumi Miyamura, Paloma Ladron De Guevara P., Manami Yamaguchi, Fumihiko Sato, Sally Mizroch, Lisa Schlender, Jay Barlow, Terrance Quinn Ii
United States Department of Commerce: Staff Publications
Despite the extensive use of photographic identification methods to investigate humpback whales in the North Pacific, few quantitative analyses have been conducted. We report on a comprehensive analysis of interchange in the North Pacific among three wintering regions (Mexico, Hawaii, and Japan) each with two to three subareas, and feeding areas that extended from southern California to the Aleutian Islands. Of the 6,413 identification photographs of humpback whales obtained by 16 independent research groups between 1990 and 1993 and examined for this study, 3,650 photographs were determined to be of suitable quality. A total of 1,241 matches was found by …
Mapping Ice Covered Waters From Space, Cheryl Bertoia, Michael Manore, Henrik Steen Andersen
Mapping Ice Covered Waters From Space, Cheryl Bertoia, Michael Manore, Henrik Steen Andersen
United States Department of Commerce: Staff Publications
Under a leaden April Arctic sky, the United States Coast Guard Cutter Healy left the swell of the southern Labrador Sea and entered the Arctic ice pack for the first time, settling in as if she had finally found her home. The deck log notes that at about 4 pm on the 4th April 2000, the ship’s commanding officer, Capt. Bob Garrett, assumed both the deck and the con for the momentous occasion (Figure 1). The ship entered the ice at 51° 33.0’ N, 54° 33.33’ W. The ice trials of the newest U.S. icebreaker were underway!
Evolution Of River Dolphins, Healy Hamilton, Susana Caballero, Allen G. Collins, Robert L. Brownell Jr.
Evolution Of River Dolphins, Healy Hamilton, Susana Caballero, Allen G. Collins, Robert L. Brownell Jr.
United States Department of Commerce: Staff Publications
The world's river dolphins (Inia, Pontoporia, Lipotes and Platanista) are among the least known and most endangered of all cetaceans. The four extant genera inhabit geographically disjunct river systems and exhibit highly modified morphologies, leading many cetologists to regard river dolphins as an unnatural group. Numerous arrangements have been proposed for their phylogenetic relationships to one another and to other odontocete cetaceans. These alternative views strongly affect the biogeographical and evolu- tionary implications raised by the important, although limited, fossil record of river dolphins. We present a hypothesis of river dolphin relationships based on phylogenetic analysis of three …
Global Ice And Land Climate Studies Using Scatterometer Image Data, David G. Long, Mark Drinkwater, Benjamin Holt, Sassan Saatchi, Cheryl Bertoia
Global Ice And Land Climate Studies Using Scatterometer Image Data, David G. Long, Mark Drinkwater, Benjamin Holt, Sassan Saatchi, Cheryl Bertoia
United States Department of Commerce: Staff Publications
Spaceborne scatterometers have provided continuous synoptic microwave coverage of the Earth for nearly a decade. Though these scatterometers were originally designed to measure oceanic surface winds, their data are also extremely useful in a broad range of ice and land applications, including the use of extensive scatterometer time series to determine seasonal and interannual variability and possible relationships to climate change. Under a NASA Earth Science Enterprise grant, the Scatterometer Climate Record Pathfinder (SCP) project has produced non-ocean scatterometer imagery and data products that are now publicly available for the first time (http://www.scp.byu.edu/).
Evaluation Of Operational Ssm/I Ice-Concentration Algorithms, Walter Meier, Michael Van Woert, Cheryl Bertoia
Evaluation Of Operational Ssm/I Ice-Concentration Algorithms, Walter Meier, Michael Van Woert, Cheryl Bertoia
United States Department of Commerce: Staff Publications
The United States National Ice Center (NIC) provides weekly ice analyses of the Arctic and Antarctic using information from ice reconnaissance, ship reports and high-resolution satellite imagery. In cloud-covered areas and regions lacking imagery, the higher-resolution sources are augmented by ice concentrations derived from Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave/Imager (SSMII) passive-microwave imagery. However, the SSMII-derived ice concentrations are limited by low resolution and uncertainties in thin-ice regions. Ongoing research at NIC is attempting to improve the utility of these SSMII products for operational sea-ice analyses. The refinements of operational algorithms may also aid future scientific studies. Here …
First Finding Of The Amphipod Echinogammarus Ischnus And The Mussel Dreissena Bugensis In Lake Michigan, Thomas F. Nalepa, Don W. Schloesser, Steve A. Pothoven, Darryl W. Hondorp, David L. Fanslow, Marc L. Tuchman, Guy W. Fleischer
First Finding Of The Amphipod Echinogammarus Ischnus And The Mussel Dreissena Bugensis In Lake Michigan, Thomas F. Nalepa, Don W. Schloesser, Steve A. Pothoven, Darryl W. Hondorp, David L. Fanslow, Marc L. Tuchman, Guy W. Fleischer
United States Department of Commerce: Staff Publications
The first finding of the amphipod Echinogammarus ischnus and the mussel Dreissena bugensis in Lake Michigan is documented. These two species are widespread and abundant in the lower lakes, but had not yet been reported from Lake Michigan. E. ischnus is generally considered a warmwater form that is typically associated with hard substrates and Dreissena clusters in the nearshore zone. Along the eastern shoreline of Lake Michigan, this species was present at rocky, breakwall habitats along the entire north-south axis of the lake. Although not abundant, this species was also found at soft-bottomed sites as deep as 94 m in …
Recent Declines In Benthic Macroinvertebrate Densities In Lake Ontario, Stephen J. Lozano, Jill V. Scharold, Thomas F. Nalepa
Recent Declines In Benthic Macroinvertebrate Densities In Lake Ontario, Stephen J. Lozano, Jill V. Scharold, Thomas F. Nalepa
United States Department of Commerce: Staff Publications
Surveys of benthic macroinvertebrates conducted in Lake Ontario during 1994 and 1997 revealed recent declines in populations of three major taxonomic groups: Oligochaeta, Sphaeriidae, and Diporeia spp. (Amphipoda), with the most drastic reductions occurring in the latter. Results from sediment measurements were used to classify deepwater sediments into three habitat zones. Densities of all three taxa declined in the shallowest (12–88 m) of the sediment zones between 1994 and 1997; the greatest changes in density were observed for Diporeia, which declined from 3011 to 145 individuals·m–2, and for total benthic macroinvertebrates, which declined from 5831 to 1376 …
Cetacean Sightings Around The Republic Of The Maldives, April 1998, Lisa T. Ballance, R. Charles Anderson, Robert L. Pitman, Kathleen Stafford, Abdullah Shaan, Zaha Waheed, Robert L. Brownell Jr.
Cetacean Sightings Around The Republic Of The Maldives, April 1998, Lisa T. Ballance, R. Charles Anderson, Robert L. Pitman, Kathleen Stafford, Abdullah Shaan, Zaha Waheed, Robert L. Brownell Jr.
United States Department of Commerce: Staff Publications
In April 1998, as part of a project to collect biopsy samples of putative pygmy blue whales (Balaenoptera musculus brevicauda) in the waters around the Republic of the Maldives, Indian Ocean, incidental sightings of cetaceans encountered were recorded. Using modified line-transect methods and handheld binoculars, a total of 267 sightings of 16 species of whales and dolphins were recorded during 20 at-sea days in the northeastern part of the atoll. Significant results include the following: (1) cetaceans were abundant and species diversity was high, including nearly every pantropical species of pelagic cetacean; (2) the spinner dolphin (Stenella …
The Spatial Variability Of Energy And Carbon Dioxide Fluxes At The Floor Of A Deciduous Forest, Kell Wilson, Tilden Meyers
The Spatial Variability Of Energy And Carbon Dioxide Fluxes At The Floor Of A Deciduous Forest, Kell Wilson, Tilden Meyers
United States Department of Commerce: Staff Publications
Fluxes of carbon dioxide, water and sensible heat were measured using three different eddy covariance systems above the forest floor of a closed deciduous forest (leaf area index ≈ 6). The primary objective was to examine the representativeness of a single eddy covariance system in estimating soil respiration for time scales ranging from one-half hour to more than one week. Experiments were conducted in which the eddy covariance sensors were in one of three configurations: i) collocated, ii) separated horizontally or iii) separated vertically. A measure of the variation between the three systems (CV’, related to the coefficient …
Satellite Observations Of Upper-Ocean Currents In Terra Nova Bay, Antarctica, Michael Van Woert, Walter Meier, Cheng-Zhi Zou, Andy Archer, Andrea Pellegrini, Paola Grigioni, Cheryl Bertoia
Satellite Observations Of Upper-Ocean Currents In Terra Nova Bay, Antarctica, Michael Van Woert, Walter Meier, Cheng-Zhi Zou, Andy Archer, Andrea Pellegrini, Paola Grigioni, Cheryl Bertoia
United States Department of Commerce: Staff Publications
Ship and iceberg drifts, along with data from modern satellite-tracked drifting buoys, portray generally northward flow in the southwest Ross Sea. Less is known, however, about the ocean variability in this region. Here we use Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) imagery to describe a cyclonically rotating gyre in Terra Nova Bay, Antarctica (75° S, 165° E). The image sequence is taken from an exceptionally clear, calm, period during winter 1998. Surface currents, derived from tracking drifting ice with a maximum cross-correlation algorithm, were found to be ~20 to 30 cm s-1. Based on scaling …
Retroposon Analysis Of Major Cetacean Lineages: The Monophyly Of Toothed Whales And The Paraphyly Of River Dolphins, Masato Nikaido, Fumio Matsuno, Healy Hamilton, Robert L. Brownell Jr., Yin Cao, Wang Ding, Zhu Zuoyan, Andrew Shedlock, R. Ewan Fordyce, Masami Hasegawa, Norihiro Okada
Retroposon Analysis Of Major Cetacean Lineages: The Monophyly Of Toothed Whales And The Paraphyly Of River Dolphins, Masato Nikaido, Fumio Matsuno, Healy Hamilton, Robert L. Brownell Jr., Yin Cao, Wang Ding, Zhu Zuoyan, Andrew Shedlock, R. Ewan Fordyce, Masami Hasegawa, Norihiro Okada
United States Department of Commerce: Staff Publications
SINE (short interspersed element) insertion analysis elucidates contentious aspects in the phylogeny of toothed whales and dolphins (Odontoceti), especially river dolphins. Here, we characterize 25 informative SINEs inserted into unique genomic loci during evolution of odontocetes to construct a cladogram, and determine a total of 2.8 kb per taxon of the flanking sequences of these SINE loci to estimate divergence times among lineages. We demonstrate that: (i) Odontocetes are monophyletic; (ii) Ganges River dolphins, beaked whales, and ocean dolphins diverged (in this order) after sperm whales; (iii three other river dolphin taxa, namely the Amazon, …
Book Review Of Cetacean Societies: Field Studies Of Whales And Dolphins Edited By I. Mann, R. C. Connor, P. L. Tyack & H. Whitehead, David Weller
United States Department of Commerce: Staff Publications
Studying the sociobiology and behavioral ecology of cetaceans is particularly challenging due in large part to the aquatic environment in which they live. Nevertheless, many of the obstacles traditionally associated with data gathering on tree-ranging whales, dolphins and porpoises are rapidly being overcome, and are now far less formidable. During the past several decades, marine mammal scientists equipped with innovative research methods and new technologies have taken field-based behavioral studies to a new level of sophistication. In some cases, as is true for bottlenose dolphins, killer whales, sperm whales and humpback whales, modern research paradigms in the marine environment are …
Remote Sensing Of Biotic Effects: Zebra Mussels (Dreissena Polymorpha) Influence On Water Clarity In Saginaw Bay, Lake Huron, Judith W. Budd, Thomas D. Drummer, Thomas F. Nalepa, Gary L. Fahnenstiel
Remote Sensing Of Biotic Effects: Zebra Mussels (Dreissena Polymorpha) Influence On Water Clarity In Saginaw Bay, Lake Huron, Judith W. Budd, Thomas D. Drummer, Thomas F. Nalepa, Gary L. Fahnenstiel
United States Department of Commerce: Staff Publications
In this study, Advanced Very High Resolution Radiometer (AVHRR) remote sensing reflectance (Rrs), imagery from 1987–1993 is used to study changes in water clarity before and after zebra mussels (Dreissena polymorpha) were discovered in Saginaw Bay, Lake Huron. Spatial and temporal trends in the data indicate distinct and persistent increases in water clarity in the inner bay after the first large recruitment of zebra mussels in the fall of 1991. The pre-Dreissena imagery show that turbidity in the inner bay was influenced by the Saginaw River discharge in spring, biological production (plankton) in summer, and …
Changes In Diet And Body Condition Of Lake Whitefish In Southern Lake Michigan Associated With Changes In Benthos, Steven A. Pothoven, Thomas F. Nalepa, Philip J. Schneeberger, Stephen B. Brandt
Changes In Diet And Body Condition Of Lake Whitefish In Southern Lake Michigan Associated With Changes In Benthos, Steven A. Pothoven, Thomas F. Nalepa, Philip J. Schneeberger, Stephen B. Brandt
United States Department of Commerce: Staff Publications
We evaluated the long-term trends of the benthic macroinvertebrate community (1980–1999) and biological attributes of lake whitefish Coregonus clupeaformis (1985–1999) in southeastern Lake Michigan. We also determined what food types were important to lake whitefish in an area where the amphipod Diporeia had not yet declined in 1998 and how the diet of lake whitefish changed as Diporeia declined during 1999–2000. Zebra mussels Dreissena polymorpha invaded the study area in 1992; Diporeia began to decline in 1993 and was nearly absent by 1999. The body condition of lake whitefish decreased after 1993 and remained low thereafter. The length at age …
Zebra Mussel (Dreissena Polymorpha) Selective Filtration Promoted Toxic Microcystis Blooms In Saginaw Bay (Lake Huron) And Lake Erie, Henry A. Vanderploeg, James R. Liebig, Wayne W. Carmichael, Megan A. Agy, Thomas H. Johengen, Gary L. Fahnenstiel, Thomas F. Nalepa
Zebra Mussel (Dreissena Polymorpha) Selective Filtration Promoted Toxic Microcystis Blooms In Saginaw Bay (Lake Huron) And Lake Erie, Henry A. Vanderploeg, James R. Liebig, Wayne W. Carmichael, Megan A. Agy, Thomas H. Johengen, Gary L. Fahnenstiel, Thomas F. Nalepa
United States Department of Commerce: Staff Publications
Microcystis aeruginosa, a planktonic colonial cyanobacterium, was not abundant in the 2-year period before zebra mussel (Dreissena polymorpha) establishment in Saginaw Bay (Lake Huron) but became abundant in three of five summers subsequent of mussel establishment. Using novel methods, we determined clearance, capture, and assimilation rates for zebra mussels feeding on natural and laboratory M. aeruginosa strains offered alone or in combination with other algae. Results were consistent with the hypothesis that zebra mussels promoted blooms of toxic M. aeruginosa in Saginaw Bay, western Lake Erie, and other lakes through selective rejection in pseudofeces. Mussels exhibited high …