Wind-sea surface temperature-sea ice relationship in the Chukchi-Beaufort Seas during autumn

Science.gov (United States)

Zhang, Jing; Stegall, Steve T.; Zhang, Xiangdong

2018-03-01

Dramatic climate changes, especially the largest sea ice retreat during September and October, in the Chukchi-Beaufort Seas could be a consequence of, and further enhance, complex air-ice-sea interactions. To detect these interaction signals, statistical relationships between surface wind speed, sea surface temperature (SST), and sea ice concentration (SIC) were analyzed. The results show a negative correlation between wind speed and SIC. The relationships between wind speed and SST are complicated by the presence of sea ice, with a negative correlation over open water but a positive correlation in sea ice dominated areas. The examination of spatial structures indicates that wind speed tends to increase when approaching the ice edge from open water and the area fully covered by sea ice. The anomalous downward radiation and thermal advection, as well as their regional distribution, play important roles in shaping these relationships, though wind-driven sub-grid scale boundary layer processes may also have contributions. Considering the feedback loop involved in the wind-SST-SIC relationships, climate model experiments would be required to further untangle the underlying complex physical processes.

High incorporation of carbon into proteins by the phytoplankton of the Bering Strait and Chukchi Sea

Science.gov (United States)

Lee, Sang H.; Kim, Hak-Jun; Whitledge, Terry E.

2009-07-01

High incorporation of carbon into proteins and low incorporation into lipids were a characteristic pattern of the photosynthetic allocations of phytoplankton throughout the euphotic zone in the Bering Strait and Chukchi Sea in 2004. According to earlier studies, this indicates that phytoplankton had no nitrogen limitation and a physiologically healthy condition, at least during the cruise period from mid-August to early September in 2004. This is an interesting result, especially for the phytoplankton in the Alaskan coastal water mass-dominated region in the Chukchi Sea which has been thought to be potentially nitrogen limited. The relatively high ammonium concentration is believed to have supported the nitrogen demand of the phytoplankton in the region where small cells (stress than large phytoplankton. If the high carbon incorporation into proteins by the phytoplankton in 2004 is a general pattern of the photosynthetic allocations in the Chukchi Sea, they could provide nitrogen-sufficient food for the highest benthic faunal biomass in the Arctic Ocean, sustaining large populations of benthic-feeding marine mammals and seabirds.

Anthropogenic {sup 129}I in the North Pacific, Bering and Chukchi Seas, and Arctic Ocean in 2012–2013

Energy Technology Data Exchange (ETDEWEB)

Nagai, H., E-mail: hnagai@chs.nihon-u.ac.jp [Department of Chemistry, College of Humanities and Sciences, Nihon University, Tokyo 156-8550 (Japan); Hasegawa, A. [Graduate School of Integrated Basic Sciences, Nihon University, Tokyo 156-8550 (Japan); Yamagata, T. [Department of Chemistry, College of Humanities and Sciences, Nihon University, Tokyo 156-8550 (Japan); Kumamoto, Y.; Nishino, S. [Japan Agency for Marine-Earth Science and Technology, Kanagawa 237-0061 (Japan); Matsuzaki, H. [Department of Nuclear Engineering and Management, The University of Tokyo, Tokyo 113-0032 (Japan)

2015-10-15

Most of anthropogenic {sup 129}I in marine environment are due to discharge from the nuclear fuel reprocessing facilities at Sellafield (U.K.) and La Hague (France) for past few decades. The discharge raised {sup 129}I concentration in seawaters in the North Atlantic and Arctic Oceans to more than 10{sup 9} atoms L{sup −1}, which is two orders of magnitude higher than that in other region. Recently, in March 2011, a large quantity of {sup 129}I was released into the western North Pacific due to the Fukushima Daiichi Nuclear Power Plant (F1NPP) accident. To evaluate the influence of these events, we have measured {sup 129}I concentration in seawaters in the northern North Pacific Ocean, Bering and Chukchi Seas, and Arctic Ocean in 2012–2013. The {sup 129}I concentrations were 1.0–1.8 × 10{sup 7} atoms L{sup −1} in the surface waters in the vicinity of 47°N 150°E–130°W North Pacific Ocean, Bering Sea, and Chukchi Sea (<74°N), which are equal to or lower than the {sup 129}I concentration level in surface water in the North Pacific Ocean before the F1NPP accident. The vertical profiles in the North Pacific were almost same as that observed in the western North Pacific before the F1NPP accident. The {sup 129}I distribution in seawater in the North Pacific to the Chukchi Sea revealed no significant increase of {sup 129}I concentration caused by the F1NPP accident. The {sup 129}I concentrations were 13–14 × 10{sup 7} atoms L{sup −1} in surface waters and 80 × 10{sup 7} atoms L{sup −1} at depths of 300 and 800 m in the Arctic Ocean.

Physical, chemical, biological, geophysical, and meteorological data collected in the Arctic Ocean and Chukchi Sea in support of the Chukchi Sea Environmental Studies Program (CSESP) from 2007 to 2014 (NODC Accession 0124308)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set was collected as part of the Chukchi Sea Environmental Studies Program (CSESP), a multi-year, interdisciplinary ecological study focused on areas in...

Geology and assessment of undiscovered oil and gas resources of the Chukchi Borderland Province, 2008

Science.gov (United States)

Bird, Kenneth J.; Houseknecht, David W.; Moore, Thomas E.; Gautier, Donald L.

2017-12-22

The Chukchi Borderland is both a stand-alone petroleum province and assessment unit (AU) that lies north of the Chukchi Sea. It is a bathymetrically high-standing block of continental crust that was probably rifted from the Canadian continental margin. The sum of our knowledge of this province is based upon geophysical data (seismic, gravity, and magnetic) and a limited number of seafloor core and dredge samples. As expected from the limited data set, the basin’s petroleum potential is poorly known. A single assessment unit, the Chukchi Borderland AU, was defined and assigned an overall probability of about a 5 percent chance of at least one petroleum accumulation >50 million barrels of oil equivalent (MMBOE). No quantitative assessment of sizes and numbers of petroleum accumulations was conducted for this AU.

Diet compositions and trophic guild structure of the eastern Chukchi Sea demersal fish community

Science.gov (United States)

Whitehouse, George A.; Buckley, Troy W.; Danielson, Seth L.

2017-01-01

Fishes are an important link in Arctic marine food webs, connecting production of lower trophic levels to apex predators. We analyzed 1773 stomach samples from 39 fish species collected during a bottom trawl survey of the eastern Chukchi Sea in the summer of 2012. We used hierarchical cluster analysis of diet dissimilarities on 21 of the most well sampled species to identify four distinct trophic guilds: gammarid amphipod consumers, benthic invertebrate generalists, fish and shrimp consumers, and zooplankton consumers. The trophic guilds reflect dominant prey types in predator diets. We used constrained analysis of principal coordinates (CAP) to determine if variation within the composite guild diets could be explained by a suite of non-diet variables. All CAP models explained a significant proportion of the variance in the diet matrices, ranging from 7% to 25% of the total variation. Explanatory variables tested included latitude, longitude, predator length, depth, and water mass. These results indicate a trophic guild structure is present amongst the demersal fish community during summer in the eastern Chukchi Sea. Regular monitoring of the food habits of the demersal fish community will be required to improve our understanding of the spatial, temporal, and interannual variation in diet composition, and to improve our ability to identify and predict the impacts of climate change and commercial development on the structure and functioning of the Chukchi Sea ecosystem.

Gray whale distribution relative to benthic invertebrate biomass and abundance: Northeastern Chukchi Sea 2009-2012

Science.gov (United States)

Brower, Amelia A.; Ferguson, Megan C.; Schonberg, Susan V.; Jewett, Stephen C.; Clarke, Janet T.

2017-10-01

The shallow continental shelf waters of the Bering and Chukchi seas are the northernmost foraging grounds of North Pacific gray whales (Eschrichtius robustus). Benthic amphipods are considered the primary prey of gray whales in these waters, although no comprehensive quantitative analysis has been performed to support this assumption. Gray whale relative abundance, distribution, and behavior in the northeastern Chukchi Sea (69°-72°N, 155-169°W) were documented during aerial surveys in June-October 2009-2012. Concurrently, vessel-based benthic infaunal sampling was conducted in the area in July-August 2009-10, September 2011, and August 2012. Gray whales were seen in the study area each month that surveys were conducted, with the majority of whales feeding. Statistical analyses confirm that the highest densities of feeding gray whales were associated with high benthic amphipod abundance, primarily within 70 km of shore from Point Barrow to Icy Cape, in water whales were not seen in 40-km×40-km cells containing benthic sampling stations with 85 m-2 or fewer amphipods. Continuing broad-scale aerial surveys in the Chukchi Sea and prey sampling near feeding gray whales will be an important means to monitor and document ongoing and predicted ecosystem changes.

Multi-year study of the carbonate system in the Chukchi Sea with emphasizes on its western part

Science.gov (United States)

Semiletov, I. P.; Pipko, I.; Pugach, S.

2015-12-01

Variability of the Arctic climate has affected many aspects of the Arctic environment, especially in the Pacific sector of the Arctic. The primary implication is that today's Arctic cryosphere (glaciers, frozen ground, and sea ice) and biosphere (terrestrial, lacustrine, and marine) are not at steady state; they have changed and will continue to change in response to evolving Arctic climate. Over the decade 2004-2013 environmental changes in the Pacific sector of the Arctic have been dramatic enough to suggest that a 'new normal' climate is emerging (Wood et al., 2015). Like everywhere in the Arctic, understanding of environmental change in the Chukchi Sea is hindered by sparse data. Dynamics of the carbonate system (CS) in the eastern Chukchi Sea (US EEZ) has been studied more extensively for a longer period and is better understood than in its western (Russian EEZ) part. Here we focus on the carbonate system data collected in the Russian part of the Chukchi Sea over > 10 years (2000-2011). Our data exhibit a strong mesoscale and interannual dynamics of carbonate system parameters in the surface seawater. The aragonite saturation state (WAr) was highly variable but also has generally been decreasing in the upper waters from 2000 to 2011. It was shown that despite strong sea ice loss, waters heating and storm increasing, the surface waters in this area have been consistently undersaturated by CO2 with respect to the atmosphere. Notable localized exceptions, where CO2 outgassing occurs, include the well-mixed waters near Bering Strait. Combining our long-term carbonate system data set (1996-2011) with the available literature data we felt in conclusion that the entire Chukchi Sea during ice-free season absorbs ~12-15× 1012 g C and a significant part of this carbon was transferred to the deep layers and insulated from contact with the atmosphere for a long time. Note that the CO2 invasion is a similar value with the CO2 outgassing from the shallow eastern Laptev Sea

Arctic Storms and Their Influence on Surface Climate in the Chukchi-Beaufort Seas

Science.gov (United States)

Yang, Y.; Zhang, X.; Rinke, A.; Zhang, J.

2017-12-01

Increases in the frequency and intensity of Arctic storms and resulting weather hazards may endanger the offshore environment, coastal community, and energy infrastructure in the Arctic as sea ice retreats. Advancing ability to identify fine-scale variations in surface climate produced by progressively stronger storm would be extremely helpful to resources management and sustainable development for coastal community. In this study, we analyzed the storms and their impacts on surface climate over the Beaufort-Chukchi seas by employing the date sets from both the hindcast simulations of the coupled Arctic regional climate model HIRHAM-NAOSIM and the recently developed Chukchi-Beaufort High-resolution Atmospheric Reanalysis (CBHAR). Based on the characteristics of spatial pattern and temporal variability of the Arctic storm activity, we categorized storms to three groups with their different origins: the East Siberia Sea, Alaska and the central Arctic Ocean. The storms originating from the central Arctic Ocean have the strongest intensity in winter with relatively less storm number. Storms traveling from Alaska to the Beaufort Sea most frequently occurred in autumn with weaker intensity. A large portion of storms originated from the East Siberia Sea region in summer. Further statistical analysis suggests that increase in surface air temperature and wind speed could be attributed to the increased frequency of storm occurrence in autumn (September to November) along the continental shelf in the Beaufort Sea.

Currents, Temperature, Salinity, and Sea Ice measurements from moorings in Barrow Canyon, Chukchi Sea, 2010-2015 (NCEI Accession 0160090)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — From August 2010 – September 2012, six moorings (BC1 inshore to BC6 offshore), spaced ~13 km apart, spanned the head of Barrow Canyon, Chukchi Sea, Alaska. Each...

Paleoecology of late-glacial peats from the bering land bridge, Chukchi Sea shelf region, northwestern Alaska

Science.gov (United States)

Elias, S.A.; Short, S.K.; Phillips, R.L.

1992-01-01

Insect fossils and pollen from late Pleistocene nonmarine peat layers were recovered from cores from the shelf region of the Chukchi Sea at depths of about 50 m below sea level. The peats date to 11,300-11,000 yr B.P. and provide a limiting age for the regional Pleistocene-Holocene marine transgression. The insect fossils are indicative of arctic coastal habitats like those of the Mackenzie Delta region (mean July temperatures = 10.6-14??C) suggesting that 11,000 yr ago the exposed Chukchi Sea shelf had a climate substantially warmer than modern coastal regions of the Alaskan north slope. The pollen spectra are consistent with the age assignment to the Birch Interval (14,000-9000 yr B.P.). The data suggest a meadow-like graminoid tundra with birch shrubs and some willow shrubs growing in sheltered areas. ?? 1992.

BAROMETRIC PRESSURE and Other Data from ALPHA HELIX From Chukchi Sea from 19950824 to 19950901 (NODC Accession 9500160)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Conductivity, Temperature and Depth (CTD) and other data were collected from 73 stations in Chukchi Sea and East Siberian Sea area. The station numbers are 1-6,...

Grain size analysis data collected by sediment corer and sediment grabber casts in the Chukchi sea from 1986-08-29 to 1987-10-07 (NODC Accession 9500158)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Grain size analysis data were collected by using sediment corer and sediment graber casts in the Chukchi Sea and NW Coast of Alaska by the Chukchi Sea. Data were...

AFSC/NMML: Passive acoustic sonobuoy recordings from Bering, Chukchi, and Beaufort Seas in Alaska, 2007-2014

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The National Marine Mammal Laboratory (NMML) has conducted passive acoustic monitoring in the Bering, Chukchi, and Western Beaufort Seas to determine spatio-temporal...

Synoptic eddy-resolving Ocean Surveys over the Slope of the Chukchi Sea 2016 and 2017

Science.gov (United States)

Muenchow, A.; Elmer, C.; Badiey, M.; Eickmeier, J.; Ryan, P. A.

2017-12-01

Mild weather and warm waters kept the outer continental shelf of the Chukchi Sea ice-free in 2016 when we conducted ocean surveys as part of the Canada Basin Acoustic Propagation Experiment (CANAPE). We used standard CTD and ADCP profiling systems aboard R/V Sikuliaq to describe ocean density and velocity fields at 3 km scales across and 6 km scales along the slope. Our survey covers 800 km2between the 100-m and 400-m isobaths and resolves the internal Rossby radius of deformation which represents the dominant spatial (or eddy) scale for a density-stratified ocean. Our early November 2016 data revealed Bering Sea Summer Waters with temperatures exceeding 1.0 C at 80-m depth near the 200-m isobath. Three-dimensional distribution of this water and associated density gradients suggests a current to the east. The flow is likely unstable, we speculate, because it spawns eddy-like features that we will describe. We will test this hypothesis with ocean current shear estimated from vessel-mounted ADCP profiles. A similar survey is planned for October 2017, when USCGC Healy will re-visit the area to recover ocean moorings deployed prior to the 2016 surveys.

Chemical and benthos data collected from CTD, bottle, and other instruments in the Chukchi Sea in 2009-2010 as part of the Chukchi Sea Offshore Monitoring in Drilling Area - Chemical and Benthos (COMIDA-CAB) project (NODC Accession 0095566)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains physical, chemical, and biological data collected during research cruises for the Chukchi Sea Offshore Monitoring in Drilling Area (Chemical...

Variability, trends, and predictability of seasonal sea ice retreat and advance in the Chukchi Sea

Science.gov (United States)

Serreze, Mark C.; Crawford, Alex D.; Stroeve, Julienne C.; Barrett, Andrew P.; Woodgate, Rebecca A.

2016-10-01

As assessed over the period 1979-2014, the date that sea ice retreats to the shelf break (150 m contour) of the Chukchi Sea has a linear trend of -0.7 days per year. The date of seasonal ice advance back to the shelf break has a steeper trend of about +1.5 days per year, together yielding an increase in the open water period of 80 days. Based on detrended time series, we ask how interannual variability in advance and retreat dates relate to various forcing parameters including radiation fluxes, temperature and wind (from numerical reanalyses), and the oceanic heat inflow through the Bering Strait (from in situ moorings). Of all variables considered, the retreat date is most strongly correlated (r ˜ 0.8) with the April through June Bering Strait heat inflow. After testing a suite of statistical linear models using several potential predictors, the best model for predicting the date of retreat includes only the April through June Bering Strait heat inflow, which explains 68% of retreat date variance. The best model predicting the ice advance date includes the July through September inflow and the date of retreat, explaining 67% of advance date variance. We address these relationships by discussing heat balances within the Chukchi Sea, and the hypothesis of oceanic heat transport triggering ocean heat uptake and ice-albedo feedback. Developing an operational prediction scheme for seasonal retreat and advance would require timely acquisition of Bering Strait heat inflow data. Predictability will likely always be limited by the chaotic nature of atmospheric circulation patterns.

Trophic transfer of persistent organochlorine contaminants (OCs) within an Arctic marine food web from the southern Beaufort-Chukchi Seas

International Nuclear Information System (INIS)

Hoekstra, P.F.; O'Hara, T.M.; Fisk, A.T.; Borgaa, K.; Solomon, K.R.; Muir, D.C.G.

2003-01-01

The trophic status and biomagnification of persistent OCs within the near-shore Beaufort-Chukchi Seas food web from Barrow, AK is discussed. - Stable isotope values (δ 13 C, δ 15 N) and concentrations of persistent organochlorine contaminants (OCs) were determined to evaluate the near-shore marine trophic status of biota and biomagnification of OCs from the southern Beaufort-Chukchi Seas (1999-2000) near Barrow, AK. The biota examined included zooplankton (Calanus spp.), fish species such as arctic cod (Boreogadus saida), arctic char (Salvelinus alpinus), pink salmon (Oncorhynchus gorbuscha), and fourhorn sculpin (Myoxocephalus quadricornis), along with marine mammals, including bowhead whales (Balaena mysticetus), beluga whales (Delphinapterus leucas), ringed seals (Phoca hispida) and bearded seals (Erignathus barbatus). The isotopically derived trophic position of biota from the Beaufort-Chukchi Seas marine food web, avian fauna excluded, is similar to other coastal food webs in the Arctic. Concentrations of OCs in marine mammals were significantly greater than in fish and corresponded with determined trophic level. In general, OCs with the greatest food web magnification factors (FWMFs) were those either formed due to biotransformation (e.g. p,p'-DDE, oxychlordane) or considered recalcitrant (e.g. β-HCH, 2,4,5-Cl substituted PCBs) in most biota, whereas concentrations of OCs that are considered to be readily eliminated (e.g. γ-HCH) did not correlate with trophic level. Differences in physical-chemical properties of OCs, feeding strategy and possible biotransformation were reflected in the variable biomagnification between fish and marine mammals. The FWMFs in the Beaufort-Chukchi Seas region were consistent with reported values in the Canadian Arctic and temperate food webs, but were statistically different than FWMFs from the Barents and White Seas, indicating that the spatial variability of OC contamination in top-level marine Arctic predators is

Marine mammal observations collected using aircraft by ConocoPhillips in the Chukchi Sea, 1989-1991 and submitted as part of the ConocoPhillips and Shell Joint Monitoring Program in the Chukchi and Beaufort Seas (NODC Accession 0120533)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains vessel- and aircraft-based marine mammal surveys in the Chukchi Sea collected from 1989 to 1991. The aerial marine mammal surveys were...

AFSC/RACE/SAP: Detailed Crab Data From NOAA Fisheries Service 2012 Chukchi Sea Bottom Trawl Surveys

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains detailed crab data collected from the 2012 NOAA/NMFS/AFSC/RACE crab-groundfish bottom trawl survey of the Chukchi Sea. 71 survey stations were...

Optical properties and molecular diversity of dissolved organic matter in the Bering Strait and Chukchi Sea

Science.gov (United States)

Gonsior, Michael; Luek, Jenna; Schmitt-Kopplin, Philippe; Grebmeier, Jacqueline M.; Cooper, Lee W.

2017-10-01

Changes in the molecular composition of dissolved organic matter (DOM) and its light absorbing chromophoric component (CDOM) are of particular interest in the Arctic region because of climate change effects that lead to warmer sea surface temperatures and longer exposure to sunlight. We used continuous UV-vis (UV-vis) spectroscopy, excitation emission matrix fluorescence and ultrahigh resolution mass spectrometry during a transect from the Aleutian Islands in the Bering Sea to the Chukchi Sea ice edge through Bering Strait to determine the variability of DOM and CDOM. These data were combined with discrete sampling for stable oxygen isotopes of seawater, in order to evaluate the contributions of melted sea ice versus runoff to the DOM and CDOM components. This study demonstrated that high geographical resolution of optical properties in conjunction with stable oxygen ratios and non-targeted ultrahigh resolution mass spectrometry was able to distinguish between different DOM sources in the Arctic, including identification of labile DOM sources in Bering Strait associated with high algal blooms and sampling locations influenced by terrestrially-derived DOM, such as the terrestrial DOM signal originating from Arctic rivers and dirty/anchor sea ice. Results of this study also revealed the overall variability and chemodiversity of Arctic DOM present in the Bering and Chukchi Seas.

BAROMETRIC PRESSURE and Other Data from ALPHA HELIX From Chukchi Sea and Others from 19930709 to 19930807 (NODC Accession 9400062)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Conductivity, Temperature and Depth (CTD) and other data were collected in Bering Sea, Chukchi Sea. Data was collected from Ship ALPHA HELIX cruise Aleutian...

Physical control of the distributions of a key Arctic copepod in the Northeast Chukchi Sea

Science.gov (United States)

Elliott, Stephen M.; Ashjian, Carin J.; Feng, Zhixuan; Jones, Benjamin; Chen, Changsheng; Zhang, Yu

2017-10-01

The Chukchi Sea is a highly advective regime dominated by a barotropically driven northward flow modulated by wind driven currents that reach the bottom boundary layer of this shallow environment. A general northward gradient of decreasing temperature and food concentration leads to geographically divergent copepod growth and development rates between north and south. The physics of this system establish the biological connection potential between specific regions. The copepod Calanus glacialis is a key grazer, predator, and food source in Arctic shelf seas. Its summer distribution and abundance have direct effects on much of the food web, from phytoplankton to migrating bowhead whales. In August 2012 and 2013, C. glacialis distributions were quantified over Hanna Shoal in the northeast Chukchi Sea. Here an individual-based model with Lagrangian tracking and copepod life stage development capabilities is used to advect and develop these distributions forward and backward in time to determine the source (production locations) and sink (potential overwintering locations) regions of the transient Hanna Shoal C. glacialis population. Hanna Shoal supplies diapause competent C. glacialis to both the Beaufort Slope and the Chukchi Cap, mainly receives juveniles from the broad slope between Hanna Shoal and Herald Valley and receives second year adults from as far south as the Anadyr Gulf and as near as the broad slope between Hanna Shoal and Herald Valley. The 2013 sink region was shifted west relative to the 2012 region and the 2013 adult source region was shifted north relative to the 2012 adult source region. These connection potentials were not sensitive to precise times and locations of release, but were quite sensitive to depth of release. These patterns demonstrate how interannual differences in the physical conditions well south of Hanna Shoal play a critical role in determining the abundance and distribution of a key food source over Hanna Shoal and in the

Cloud amount/frequency, NITRATE and other data from ALPHA HELIX in the Bering Sea and Chukchi Sea from 1993-09-09 to 1993-10-10 (NODC Accession 9400036)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Conductivity, Temperature and Depth (CTD) and other data were collected in Bering Sea and Chukchi Sea. Data was collected from Ship ALPHA HELIX. The data was...

Lipid-rich and protein-poor carbon allocation patterns of phytoplankton in the northern Chukchi Sea, 2011

Science.gov (United States)

Yun, Mi Sun; Joo, Hui Tae; Park, Jung Woo; Kang, Jae Joong; Kang, Sung-Ho; Lee, Sang H.

2018-04-01

The carbon allocations of phytoplankton into different photosynthetic end products (lipids, LMWM, polysaccharides, and proteins) were determined to understand physiological conditions of phytoplankton in the northern Chukchi Sea during the Korean Arctic expedition, 2011, using the 13C isotope tracer technique. The carbon allocation rates of lipids, LMWM, polysaccharides, and proteins were 0.00009-0.00062 h-1, 0.00001-0.00049 h-1, 0.00001-0.00025 h-1, and 0.00001-0.00062 h-1 within the euphotic depths from surface to 1% light depths during our cruise period, respectively. Significant relationships between protein production rates and chlorophyll a concentrations (large and total) were found in this study. Moreover, we found a significant negative relationship between lipid production rates and ammonium concentrations. These relationships match well with the previous results for environmental/physiological conditions for phytoplankton growth. Overall, phytoplankton allocated more photosynthetic carbon into lipids (42.5 ± 17.7%) whereas relatively lower to proteins (20.4 ± 15.5%) in this study. The lipid-rich and protein-poor allocation patterns in this study suggest that phytoplankton in the northern Chukchi Sea were in a stationary growth phase under nutrient deficient condition based on biological and environmental conditions observed during our study period. Based on comparison with the previous studies in the northern Bering Sea and southern Chukchi Sea, we found that the photosynthetic carbon allocation patterns depending on physiological status of phytoplankton under the different growth and/or nutrient conditions could be largely vary at different regions in the Arctic Ocean. More intensive research on the physiological status of phytoplankton is further required to determine how phytoplankton response to the changing environmental conditions and consequently how they impact on higher trophic levels in marine ecosystems in the Arctic Ocean.

Currents, Ice Velocity, Temperature, and Salinity from moorings around Hanna Shoal, Chukchi Sea, 2012-2014 (NCEI Accession 0163833)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — These data were collected as part of the physical oceanographic component of the Chukchi Sea Offshore Monitoring in Drilling Area (COMIDA) Hanna Shoal Ecosystem...

Icthyoplankton Assemblages and Distribution in the Chukchi Sea 2012-2013

Science.gov (United States)

Busby, M. S.; Duffy-Anderson, J. T.; Mier, K. L.; Tabisola, H. M.

2016-02-01

There is significant interest in the effects of climate change on the Pacific arctic ecosystem, and in determining relationships between physical drivers and biological response. Ichthyoplankton surveys have become an integral component of ecosystem studies in the Pacific arctic over the past decade. In summer 2012 and 2013, large scale fisheries oceanographic surveys that included ichthyoplankton tows were conducted in the northern Bering and eastern Chukchi Seas as part of the Arctic Ecosystem Integrated Survey (Arctic Eis). Spatial and temporal analyses of fish larvae collected determined that yellowfin sole (Limanda aspera) was the most abundant larval fish caught followed by Arctic cod (Boreogadus saida). Cluster analyses showed L. aspera to be the dominant component of a southern, nearshore assemblage strongly associated with the northward moving Alaska Coastal Current (ACC) characterized by relatively warm-low salinity water. Boreogadus saida larvae dominated a more northern assemblage in close proximity to the ice edge and were more abundant in 2013 than 2012. Collections of pelagic fish eggs determined locations of spawning centers for L. aspera nearshore of the Seward Peninsula and Bering flounder (Hippoglossoides robustus) to the west and offshore from Point Barrow in 2012. Similar but less pronounced trends in egg distribution were observed in 2013. Larvae of the forage fish species capelin (Mallotus villosus) and Arctic sand lance (Ammodytes hexapterus) were important assemblage components in 2012 and 2013 respectively. These patterns in the distribution of eggs and larvae are similar to those observed in other studies. The influence of circulation patterns on the distributions of fish in the Chukchi Sea is being investigated and will be discussed.

Reprocessing of multi-channel seismic-reflection data collected in the Chukchi Sea

Science.gov (United States)

Agena, W.F.; Lee, M.W.; Hart, P.E.

2001-01-01

Contained on this set of two CD-ROMs are stacked and migrated multi-channel seismic-reflection data for 44 lines recorded in the Chukchi Sea, northern Alaska, by the United States Geological Survey in 1977, 1978, and 1980. All data were reprocessed by the USGS in 2000 using updated methods. The resulting final data have both increased temporal and spatial resolution thus providing improved interpretability. An added benefit of these CD-ROMs is that they are a more stable, long-term archival medium for the data.

BAROMETRIC PRESSURE and Other Data from ALPHA HELIX From Chukchi Sea and Others from 19920724 to 19921027 (NODC Accession 9300161)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Conductivity, Temperature and Depth (CTD) and other data were collected in Gulf of Alaska, Chukchi Sea, and NW Pacific (limit-180). Data was collected from...

SBI AWS02-I CTD Data collected from the Polar Star in the Beaufort and Chukchi Seas (NODC Accession 0001290)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The field phase of the Shelf-Basin Interactions Experiment (SBI) began in 2002 with a series of three cruises to the Chukchi and Beaufort Seas. SBI is a...

Short-term changes in a microplankton community in the Chukchi Sea during autumn: consequences of a strong wind event

Science.gov (United States)

Yokoi, Naoya; Matsuno, Kohei; Ichinomiya, Mutsuo; Yamaguchi, Atsushi; Nishino, Shigeto; Onodera, Jonaotaro; Inoue, Jun; Kikuchi, Takashi

2016-02-01

Recent studies indicate an increase in atmospheric turbulence in the Chukchi Sea due to the recent drastic sea-ice reduction during summer months. The importance of the effects of this atmospheric turbulence on the marine ecosystem in this region, however, is not fully understood. To evaluate the effects of atmospheric turbulence on the marine ecosystem, high-frequency sampling (daily) from five layers of the microplankton community between 0 and 30 m at a fixed station in the Chukchi Sea from 10 through 25 September 2013 was conducted. During the study period, a strong wind event (SWE) was observed on 18 and 19 September. The abundance of microplankton was 2.6 to 17.6 cells mL-1, with a maximum abundance being reported at 20 m on 22 September, while diatoms were the most dominant taxa throughout the study period. The abundance of diatoms, dinoflagellates and ciliates ranged between 1.6 and 14.1, 0.5 and 2.4 and 0.1 and 2.8 cells mL-1, respectively. Diatoms belonging to 7 genera consisting of 35 species (Cylindrotheca closterium and Leptocylindrus danicus were dominant), dinoflagellates belonging to 7 genera consisting of 25 species (Prorocentrum balticum and Gymnodinium spp. were dominant) and ciliates belonging to 7 genera consisting of 8 species (Strobilidium spp. and Strombidium spp. were dominant) were identified. Within the microplankton species, there were 11 species with abundances that increased after the SWE, while there was no species with an abundance that decreased following the SWE. It is conjectured that atmospheric turbulences, such as that of an SWE, may supply sufficient nutrients to the surface layer that subsequently enhance the small bloom under the weak stratification of the Chukchi Sea Shelf during the autumn months. After the bloom, the dominant diatom community then shifts from centric-dominated to one where centric/pennate are more equal in abundance.

Cloud amount/frequency, ANIMALS - INDIVIDUAL and other data from AIRCRAFT in the Chukchi Sea from 1987-09-01 to 1988-10-16 (NODC Accession 9100025)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The aerial surveys of Whales data in this accession were collected from aircraft by Don Llungblad over the Chukchi Sea between September 1987 and October 1988 by Sea...

Arctic shelves as platforms for biogeochemical activity: Nitrogen and carbon transformations in the Chukchi Sea, Alaska

Science.gov (United States)

Hardison, Amber K.; McTigue, Nathan D.; Gardner, Wayne S.; Dunton, Kenneth H.

2017-10-01

Continental shelves comprise 50% of marine denitrification. The Hanna Shoal region, part of the continental shelf system in the northeast Chukchi Sea, Alaska, is recognized for its high biodiversity and productivity. We investigated the role of sediments in organic matter decomposition and nutrient cycling at five stations on the shallow Hanna Shoal. In particular, we asked (1) how much sediment organic matter is remineralized in the Chukchi Sea, and what factors drive this degradation, (2) do sediments function as a net source for fixed nitrogen (thus fueling primary production in the overlying water), or as a net sink for fixed nitrogen (thereby removing it from the system), and (3) what is the balance between sediment NH4+ uptake and regeneration, and what factors drive NH4+ cycling? We conducted dark sediment core incubations to measure sediment O2 consumption, net N2 and nutrient (NH4+, NO3-, NO2-, PO43-) fluxes, and rates of sediment NH4+ cycling, including uptake and regeneration. Rates of sediment O2 consumption and NH4+ and PO43- efflux suggest that high organic matter remineralization rates occurred in these cold (-2 °C) sediments. We estimated that total organic carbon remineralization accounted for 20-57% of summer export production measured on the Chukchi Shelf. Net N2 release was the dominant nitrogen flux, indicating that sediments acted as a net sink for bioavailable nitrogen via denitrification. Organic carbon remineralization via denitrification accounted for 6-12% of summer export production, which made up 25% of the total organic carbon oxidized in Hanna Shoal sediments. These shallow, productive Arctic shelves are ;hotspots; for organic matter remineralization.

Underwater passive acoustic localization of Pacific walruses in the northeastern Chukchi Sea.

Science.gov (United States)

Rideout, Brendan P; Dosso, Stan E; Hannay, David E

2013-09-01

This paper develops and applies a linearized Bayesian localization algorithm based on acoustic arrival times of marine mammal vocalizations at spatially-separated receivers which provides three-dimensional (3D) location estimates with rigorous uncertainty analysis. To properly account for uncertainty in receiver parameters (3D hydrophone locations and synchronization times) and environmental parameters (water depth and sound-speed correction), these quantities are treated as unknowns constrained by prior estimates and prior uncertainties. Unknown scaling factors on both the prior and arrival-time uncertainties are estimated by minimizing Akaike's Bayesian information criterion (a maximum entropy condition). Maximum a posteriori estimates for sound source locations and times, receiver parameters, and environmental parameters are calculated simultaneously using measurements of arrival times for direct and interface-reflected acoustic paths. Posterior uncertainties for all unknowns incorporate both arrival time and prior uncertainties. Monte Carlo simulation results demonstrate that, for the cases considered here, linearization errors are small and the lack of an accurate sound-speed profile does not cause significant biases in the estimated locations. A sequence of Pacific walrus vocalizations, recorded in the Chukchi Sea northwest of Alaska, is localized using this technique, yielding a track estimate and uncertainties with an estimated speed comparable to normal walrus swim speeds.

Multichannel seismic-reflection data collected in 1980 in the eastern Chukchi Sea

Science.gov (United States)

Grantz, Arthur; Mann, Dennis M.; May, Steven D.

1986-01-01

The U.S. Geological Survey (USGS) collected approximately 2,652 km of 24-channel seismic-reflection data in early September, 1980, over the continental shelf in the eastern Chukchi Sea (Fig. 1). The profiles were collected on the USGS Research Vessel S.P. Lee. The seismic energy source consisted of a tuned array of five airguns with a total volume of 1213 cubic inches of air compressed to approximately 1900 psi. The recording system consisted of a 24-channel, 2400 meter long streamer with a group interval of 100 m, and a GUS (Global Universal Science) model 4200 digital recording instrument. Shots were fired every 50 meters. Navigational control for the survey was provided by a Magnavox integrated navigation system using transit satellites and doppler-sonar augmented by Loran C (Rho-Rho). A 2-millisecond sampling rate was used in the field; the data were later desampled to 4-milliseconds during the demultiplexing process. 8 seconds data length was recorded. Processing was done at the USGS Pacific Marine Geology Multichannel Processing Center in Menlo Park, California, in the sequence: editing-demultiplexing, velocity analysis, CDP stacking, deconvolution-filtering, and plotting on an electrostatic plotter. Plate 1 is a trackline chart showing shotpoint navigation.

The conservative behavior of dissolved organic carbon in surface waters of the southern Chukchi Sea, Arctic Ocean, during early summer.

Science.gov (United States)

Tanaka, Kazuki; Takesue, Nobuyuki; Nishioka, Jun; Kondo, Yoshiko; Ooki, Atsushi; Kuma, Kenshi; Hirawake, Toru; Yamashita, Youhei

2016-09-23

The spatial distribution of dissolved organic carbon (DOC) concentrations and the optical properties of dissolved organic matter (DOM) determined by ultraviolet-visible absorbance and fluorescence spectroscopy were measured in surface waters of the southern Chukchi Sea, western Arctic Ocean, during the early summer of 2013. Neither the DOC concentration nor the optical parameters of the DOM correlated with salinity. Principal component analysis using the DOM optical parameters clearly separated the DOM sources. A significant linear relationship was evident between the DOC and the principal component score for specific water masses, indicating that a high DOC level was related to a terrigenous source, whereas a low DOC level was related to a marine source. Relationships between the DOC and the principal component scores of the surface waters of the southern Chukchi Sea implied that the major factor controlling the distribution of DOC concentrations was the mixing of plural water masses rather than local production and degradation.

SBI AWS02-I Bottle and Nutrient Data collected from the Polar Star in the Beaufort and Chukchi Seas (NODC Accession 0001288)

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National Oceanic and Atmospheric Administration, Department of Commerce — The field phase of the Shelf-Basin Interactions Experiment (SBI) began in 2002 with a series of three cruises to the Chukchi and Beaufort Seas. SBI is a...

Quantifying the Bering Strait Oceanic Fluxes and their Impacts on Sea-Ice and Water Properties in the Chukchi and Beaufort Seas and Western Arctic Ocean for 2013-2014

Science.gov (United States)

2016-07-27

impacts on sea-ice and water properties in the Chukchi and Beaufort Seas and western Arctic Ocean for 2013-2014 Rebecca Woodgate Polar Science...and G. R. Bigg (2002), Impact of flow through the Canadian Archipelago and Bering Strait on the North Atlantic and Arctic circulation: an ocean ...Technical 3. DATES COVERED (From - To) Feb 2013 - April 2016 4. TITLE AND SUBTITLE Quantifying the Bering Strait oceanic fluxes and their impacts

Impacts of sea ice retreat, thinning, and melt-pond proliferation on the summer phytoplankton bloom in the Chukchi Sea, Arctic Ocean

Science.gov (United States)

Palmer, Molly A.; Saenz, Benjamin T.; Arrigo, Kevin R.

2014-07-01

In 2011, a massive phytoplankton bloom was observed in the Chukchi Sea under first-year sea ice (FYI), an environment in which primary productivity (PP) has historically been low. In this paper, we use a 1-D biological model of the Chukchi shelf ecosystem, in conjunction with in situ chemical and physiological data, to better understand the conditions that facilitated the development of such an unprecedented bloom. In addition, to assess the effects of changing Arctic environmental conditions on net PP (NPP), we perform model runs with varying sea ice and snow thickness, timing of melt, melt ponds, and biological parameters. Results from model runs with conditions similar to 2011 indicate that first-year ice (FYI) with at least 10% melt pond coverage transmits sufficient light to support the growth of shade-adapted Arctic phytoplankton. Increasing pond fraction by 20% enhanced peak under-ice NPP by 26% and produced rates more comparable to those measured during the 2011 bloom, but there was no effect of further increasing pond fraction. One of the important consequences of large under-ice blooms is that they consume a substantial fraction of surface nutrients such that NPP is greatly diminished in the marginal ice zone (MIZ) following ice retreat, where NPP has historically been the highest. In contrast, in model runs with ultraviolet radiation and zooplankton grazers reduce peak open water NPP but have little impact on under-ice NPP, which has important implications for the relative proportion of NPP concentrated in pelagic vs. benthic food webs. Finally, the shift in the relative amount of NPP occurring in under-ice vs. open-water environments may affect total ecosystem productivity.

Cloud amount/frequency, NITRATE and other data from SURVEYOR in the Chukchi Sea from 1990-10-02 to 1990-10-20 (NODC Accession 9200012)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Conductivity, Temperature and Depth (CTD) and other data were collected in Chukchi Sea. Data was collected during 155 Casts from Ship SURVEYOR. The data was...

Cloud amount/frequency, NITRATE and other data from ALPHA HELIX in the Chukchi Sea from 1992-09-21 to 1992-10-04 (NODC Accession 9300097)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Conductivity, Temperature and Depth (CTD) and other data were collected in Chukchi Sea. Data was collected from Ship ALPHA HELIX. The data was collected over a...

Do microzooplankton grazers control biomass of large-phytoplankton in the northern Bering and Chukchi Seas?

Science.gov (United States)

Krause, J. W.; Lomas, M. W.

2017-12-01

In high-latitude environments like the northern Bering and Chukchi Seas, microzooplankton and phytoplankton biomass can be tightly coupled. Microzooplankton consumption of primary production decreases the efficiency of transfer to higher trophic levels by increasing the number of food web steps and compounding losses from respiration. Thus, the balance of phytoplankton growth and microzooplankton grazing directly affects the availability of primary production to support higher-trophic processes (e.g. fisheries productivity). Despite compelling qualitative observations, there are no quantitative data demonstrating that larger phytoplankton (e.g. diatoms) growth is balanced by microzooplankton grazing in the northern Bering and Chukchi Seas. We report the first size-fractionated data for phytoplankton growth and grazing loss rates from microzooplankton in these regions during late spring 2017. Within the small size fraction (5 µm), which was presumably dominated by diatoms, less than 33% of experiments showed a potential control of growth by grazing and among these even fewer showed grazing rates statistically different from zero. In the few cases where there was a significant grazing rate, a negative correlation was observed between the microzooplankton grazing rate on large phytoplankton and chlorophyll in that size fraction; a similar negative trend was observed for these same grazing rates on large cells versus biogenic silica concentration (an independent metric of diatom biomass). These data show that the growth of large phytoplankton (e.g. diatoms) was typically decoupled from microzooplankton grazing losses, suggesting that at most stations a high proportion of this phytoplankton productivity escapes microzooplankton grazing and is available for consumption by higher trophic organisms.

Tritium and plutonium in waters from the Bering and Chukchi Seas

Science.gov (United States)

Landa, E.R.; Beals, D.M.; Halverson, J.E.; Michel, R.L.; Cefus, G.R.

1999-01-01

During the summer of 1993, seawater in the Bering and Chukchi Seas was sampled on a joint Russian-American cruise [BERPAC] of the RV Okean to determine concentrations of tritium, 239Pu and 240Pu. Concentrations of tritium were determined by electrolytic enrichment and liquid scintilation counting. Tritium levels ranged up to 420 mBq L-1 showed no evidence of inputs other than those attribute atmospheric nuclear weapons testing. Plutonium was recovered from water samples by ferric hydroxide precipitation, and concentrations were determined by thermal ionization mass spectrometry. 239+240Pu concentrations ranged from nuclear facilities in the United States. This study and others sponsored by the International Atomic Energy Agency and the Office of Naval Research's Arctic Nuclear Waste Assessment Program are providing data for the assessment of potential radiological impacts in the Arctic regions associated with nuclear waste disposal by the former Soviet Union.

Surface currents and temperature data from satellite-tracked drifters in the Chukchi and Beaufort Seas from 2011-08-07 to 2014-03-06 (NODC Accession 0126984)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Drifters were deployed from vessels in the Chukchi Sea during the ice-free seasons of 2011-2013. Drifter positions were determined via GPS, and positions were...

Marine Emissions and Atmospheric Processing Influence Aerosol Mixing States in the Bering Strait and Chukchi Sea

Science.gov (United States)

Kirpes, R.; Rodriguez, B.; Kim, S.; Park, K.; China, S.; Laskin, A.; Pratt, K.

2017-12-01

The Arctic region is rapidly changing due to sea ice loss and increasing oil/gas development and shipping activity. These changes influence aerosol sources and composition, resulting in complex aerosol-cloud-climate feedbacks. Atmospheric particles were collected aboard the R/V Araon in July-August 2016 in the Alaskan Arctic along the Bering Strait and Chukchi Sea. Offline analysis of individual particles by microscopic and spectroscopic techniques provided information on particle size, morphology, and chemical composition. Sea spray aerosol (SSA) and organic aerosol (OA) particles were the most commonly observed particle types, and sulfate was internally mixed with both SSA and OA. Evidence of multiphase sea spray aerosol reactions was observed, with varying degrees of chlorine depletion observed along the cruise. Notably, atmospherically processed SSA, completely depleted in chlorine, and internally mixed organic and sulfate particles, were observed in samples influenced by the central Arctic Ocean. Changes in particle composition due to fog processing were also investigated. Due to the changing aerosol sources and atmospheric processes in the Arctic region, it is crucial to understand aerosol composition in order to predict climate impacts.

Benthic organisms data collected using sediment sampler casts from NOAA Ship OCEANOGRAPHER in the Chukchi Sea from 1986-09-06 to 1987-10-05 (NODC Accession 8900299)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Benthic organisms data were collected using sediment sampler casts from NOAA Ship OCEANOGRAPHER in the Chukchi Sea from 06 September 1986 to 05 October 1987. Data...

A comparison between late summer 2012 and 2013 water masses, macronutrients, and phytoplankton standing crops in the northern Bering and Chukchi Seas

Science.gov (United States)

Danielson, Seth L.; Eisner, Lisa; Ladd, Carol; Mordy, Calvin; Sousa, Leandra; Weingartner, Thomas J.

2017-01-01

Survey data from the northern Bering and Chukchi sea continental shelves in August-September 2012 and 2013 reveal inter-annual differences in the spatial structure of water masses along with statistically significant differences in thermohaline properties, chemical properties, and phytoplankton communities. We provide a set of water mass definitions applicable to the northern Bering and Chukchi continental shelves, and we find that the near-bottom Bering-Chukchi Summer Water (BCSW) was more saline in 2012 and Alaskan Coastal Water (ACW) was warmer in 2013. Both of these water masses carried higher nutrient concentrations in 2012, supporting a larger chlorophyll a biomass that was comprised primarily of small (<10 μm) size class phytoplankton, so the classical relation between higher nutrient loads and larger phytoplankton does not hold for this region in late summer. The distributions of phytoplankton biomass and size structure reveal linkages between the wind fields, seafloor topography, water mass distributions and the pelagic production. The water mass structure, including the strength and location of stratification and fronts, respectively, differed primarily because of the August regional wind field, which was more energetic in 2012 but was more persistent in direction in 2013. High concentrations of ice in winter and early spring in 2012 and 2013 resembled conditions of the 1980s and early 1990s but the regional ice retreat rate has accelerated in the late 1990s and 2000s so the summer and fall ice concentrations more closely resembled those of the last two decades. Our data show that wind forcing can shut down the Alaskan Coastal Current in the NE Chukchi Sea for periods of weeks to months during the ice-covered winter and during the summer when buoyancy forcing is at its annual maximum. We hypothesize that a decrease in salinity and nutrients from 2012 to 2013 was a consequence of a decreased net Bering Strait transport from 2011 to 2012. Biological

Dancing on Thinning Ice: Choreography and Science in the Chukchi Sea

Science.gov (United States)

Sperling, J.

2016-12-01

In 2014, Jody Sperling was the first-ever choreographer in residence to participate in a polar science mission, thanks to an invitation from Dr. Robert Pickart (Woods Hole Oceanographic Institution). This 43-day mission (SUBICE) aboard the USCGC Healy traveled to the Chukchi Sea with Sperling serving as part of an outreach team on climate science communication. Since the mission, Sperling has shared her Arctic experience with more than 4,200 people through dozens of live performances, lectures and workshops, plus press coverage across the US. Her film "Ice Floe," created during SUBICE, won a Creative Climate Award and has been aired on Alaska Public Television reaching thousands more. While Arctic sea ice is vitally important to the global climate system, the public knows little about its function (other than as a habitat for polar bears) or its precipitous decline. Sperling's research during the mission focused on sea ice and had three components: 1) As a contributor to SUBICE's Ice Watch Survey, she learned the descriptive nomenclature for sea ice and its processes of formation to transport its dynamics and aesthetics to the stage. This information served as critical inspiration for the creation of her dance work "Ice Cycle" (2015); 2) Sperling collected media samples of sea ice that were subsequently used in performances of "Ice Cycle" as well as her frequent public lectures; 3) Sperling danced on sea ice at a dozen ice stations. In collaboration with the WHOI outreach team, the SUBICE science party and the Healy crew, she created the dance film short "Ice Floe". Sperling's dance company, Time Lapse Dance, has performed "Ice Cycle" as part of the larger program "Bringing the Arctic Home" at many venues nationally and the work has been mounted on students at Brenau University in Georgia. Wherever she performs, Sperling programs talkbacks, lectures and panels with scientists, artists and climate educators, with the aim of increasing awareness of sea ice, the rapid

Food habits of Arctic staghorn sculpin (Gymnocanthus tricuspis) and shorthorn sculpin (Myoxocephalus scorpius) in the northeastern Chukchi and western Beaufort Seas

Science.gov (United States)

Gray, Benjamin P.; Norcross, Brenda L.; Beaudreau, Anne H.; Blanchard, Arny L.; Seitz, Andrew C.

2017-01-01

Arctic staghorn sculpin (Gymnocanthus tricuspis) and shorthorn sculpin (Myoxocephalus scorpius) belong to Cottidae, the second most abundant fish family in the western Arctic. Although considered important in food webs, little is known about their food habits throughout this region. To address this knowledge gap, we examined and compared the diets of 515 Arctic staghorn sculpin and 422 shorthorn sculpin using stomachs collected over three summers in the northeastern Chukchi Sea (2010-2012) and one summer in the western Beaufort Sea (2011). We used permutational multivariate analysis of variance (PERMANOVA) and non-metric multidimensional scaling (nMDS) to compare sculpin diets between regions and selected size classes. Differences in mouth morphologies and predator size versus prey size relationships were examined using regression techniques. Arctic staghorn sculpin and shorthorn sculpin diet compositions differed greatly throughout the Chukchi and Beaufort Seas. Regardless of body size, the smaller-mouthed Arctic staghorn sculpin consumed mostly benthic amphipods and polychaetes, whereas the larger-mouthed shorthorn sculpin shifted from a diet composed of benthic and pelagic macroinvertebrates as smaller individuals to shrimps and fish prey as larger individuals. Within shared habitats, the sculpins appear to partition prey, either by taxa or size, in a manner that suggests no substantial overlap occurs between species. This study increases knowledge of sculpin feeding ecology in the western Arctic and offers regional, quantitative diet information that could support current and future food web modeling efforts.

Emerging Trends in the Sea State of the Beaufort and Chukchi Seas

Science.gov (United States)

2016-07-06

reduced ice cover with specific storm ac- tivity, such as in August 2012 ( Simmonds and Keay, 2012; Zhang et al., 2013; Parkinson and Comiso, 2013...Of these, Parkinson and Comiso (2013) conclude that the storm reduced the September ice extent minimum by an additional 5 percent. This relatively...arrows), ice-edge (magenta curve), Beaufort–Chukchi domain (white outline box ), and ice-normal energy flux time series (lower panel). The red dot in

Marine geology and bathymetry of nearshore shelf of Chukchi Sea, Ogotoruk Creek area, northwest Alaska

Science.gov (United States)

Scholl, D. W.; Sainsbury, C.L.

1960-01-01

During July and August 1958 the U.S. Geological Survey conducted a study in behalf of the Atomic Energy Commission of the oceanography, bathymetry, and marine geology of the nearshore shelf of the Chukchi Sea off the Ogotoruk Creek area, northwest Alaska. Ogotoruk Creek enters the Chukchi Sea about 32 miles southeast of the large cuapate spit of Point Hope at long 165 degrees 4446 W. and lat 68 degrees 0551 N. The Ogotoruk Creek area extends approximately 10 miles west and 7 miles east of the creek mouth. Knowledge of the marine geology and oceanography is confined primarily to the nearshore shelf, which includes about 70 square miles of the shelf and is defined as the sea floor lying shoreward of the 50-foot submarine contour. The 50-foot contour generally lies from 2 to 4 miles from shore. Submarine topography was studied to a distance of 15 miles from shore over an area of approximately 340 square miles. A northwest coastal current flows past the Ogotoruk Creek area and during July and August averaged 0.5 mile per hour. Persistent northerly winds cause general upwelling near shore and at times of pronounced upwelling the coastal current was reversed or appreciably reduced in speed. Longshore currents shoreward of the breaker zone averaged 0.3 mile per hour and moved to the east for the greater part of the time of the study. The overall seaward slope of the inner 15 miles of the Chukchi shelf from a depth of 40 to 135 feet is approximately 0 degrees 04, or about 6 feet per mile. Slopes near shore to depths of 15-20 feet are steep and average 2 degrees 30. Beyond these depths they increase gradually out to a depth of 40-45 feet. Seaward of this point the shelf is flattest and slopes are as low as 0 degree 01. This terrace or flat part of the nearshore shelf is about 2 miles wide and descends to a depth of 50-55 feet beyond which the gradient increases to about 0 degree 06. At depths greater than 85 feet the submarine declivity gradually decreases to 0 degree 03 at

Deglacial sea level history of the East Siberian Sea and Chukchi Sea margins

Science.gov (United States)

Cronin, Thomas M.; O'Regan, Matt; Pearce, Christof; Gemery, Laura; Toomey, Michael; Semiletov, Igor; Jakobsson, Martin

2017-09-01

Deglacial (12.8-10.7 ka) sea level history on the East Siberian continental shelf and upper continental slope was reconstructed using new geophysical records and sediment cores taken during Leg 2 of the 2014 SWERUS-C3 expedition. The focus of this study is two cores from Herald Canyon, piston core SWERUS-L2-4-PC1 (4-PC1) and multicore SWERUS-L2-4-MC1 (4-MC1), and a gravity core from an East Siberian Sea transect, SWERUS-L2-20-GC1 (20-GC1). Cores 4-PC1 and 20-GC were taken at 120 and 115 m of modern water depth, respectively, only a few meters above the global last glacial maximum (LGM; ˜ 24 kiloannum or ka) minimum sea level of ˜ 125-130 meters below sea level (m b.s.l.). Using calibrated radiocarbon ages mainly on molluscs for chronology and the ecology of benthic foraminifera and ostracode species to estimate paleodepths, the data reveal a dominance of river-proximal species during the early part of the Younger Dryas event (YD, Greenland Stadial GS-1) followed by a rise in river-intermediate species in the late Younger Dryas or the early Holocene (Preboreal) period. A rapid relative sea level rise beginning at roughly 11.4 to 10.8 ka ( ˜ 400 cm of core depth) is indicated by a sharp faunal change and unconformity or condensed zone of sedimentation. Regional sea level at this time was about 108 m b.s.l. at the 4-PC1 site and 102 m b.s.l. at 20-GC1. Regional sea level near the end of the YD was up to 42-47 m lower than predicted by geophysical models corrected for glacio-isostatic adjustment. This discrepancy could be explained by delayed isostatic adjustment caused by a greater volume and/or geographical extent of glacial-age land ice and/or ice shelves in the western Arctic Ocean and adjacent Siberian land areas.

Marine mammal observations collected by aircraft and ship and submitted as part of the ConocoPhillips and Shell Joint Monitoring Program in the Chukchi and Beaufort Seas, 2006-2010 (NODC Accession 0120532)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains vessel- and aircraft-based mammal sightings data and associated environmental data collected in the Chukchi and Beaufort seas during the open...

Seasonal variation of CaCO3 saturation state in bottom water of a biological hotspot in the Chukchi Sea, Arctic Ocean

Directory of Open Access Journals (Sweden)

M. Yamamoto-Kawai

2016-11-01

Full Text Available Distribution of calcium carbonate saturation state (Ω was observed in the Chukchi Sea in autumn 2012 and early summer 2013. Ω in bottom water ranged from 0.3 to 2.0 for aragonite and from 0.5 to 3.2 for calcite in 2012. In 2013, Ω in bottom water was 1.1–2.8 for aragonite and 1.7–4.4 for calcite. Aragonite and calcite undersaturation was found in high productivity regions in autumn 2012 but not in early summer 2013. Comparison with other parameters has indicated that biological processes – respiration and photosynthesis – are major factors controlling the regional and temporal variability of Ω. From these ship-based observations, we have obtained empirical equations to reconstruct Ω from temperature, salinity and apparent oxygen utilization. Using 2-year-round mooring data and these equations, we have reconstructed seasonal variation of Ω in bottom water in Hope Valley, a biological hotspot in the southern Chukchi Sea. Estimated Ω was high in spring and early summer, decreased in later summer, and remained relatively low in winter. Calculations indicated a possibility that bottom water could have been undersaturated for aragonite on an intermittent basis even in the pre-industrial period, and that anthropogenic CO2 has extended the period of aragonite undersaturation to more than 2-fold longer by now.

Eastward and northward components of ocean current, temperature, salinity and ice analysis collected from industry sponsored moorings in the Chukchi Sea, Alaska from 2008-09-08 to 2016-10-13 (NCEI Accession 0164964)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Thirteen moorings sites throughout the northeastern Chukchi Sea shelf were occupied in various combinations for eight field years, 2008-2016. Two separate taut line...

Deglacial sea level history of the East Siberian Sea and Chukchi Sea margins

Science.gov (United States)

Cronin, Thomas M.; O'Regan, Matt; Pearce, Christof; Gemery, Laura; Toomey, Michael; Semiletov, Igor

2017-01-01

Deglacial (12.8–10.7 ka) sea level history on the East Siberian continental shelf and upper continental slope was reconstructed using new geophysical records and sediment cores taken during Leg 2 of the 2014 SWERUS-C3 expedition. The focus of this study is two cores from Herald Canyon, piston core SWERUS-L2-4-PC1 (4-PC1) and multicore SWERUS-L2-4-MC1 (4-MC1), and a gravity core from an East Siberian Sea transect, SWERUS-L2-20-GC1 (20-GC1). Cores 4-PC1 and 20-GC were taken at 120 and 115 m of modern water depth, respectively, only a few meters above the global last glacial maximum (LGM;  ∼  24 kiloannum or ka) minimum sea level of  ∼  125–130 meters below sea level (m b.s.l.). Using calibrated radiocarbon ages mainly on molluscs for chronology and the ecology of benthic foraminifera and ostracode species to estimate paleodepths, the data reveal a dominance of river-proximal species during the early part of the Younger Dryas event (YD, Greenland Stadial GS-1) followed by a rise in river-intermediate species in the late Younger Dryas or the early Holocene (Preboreal) period. A rapid relative sea level rise beginning at roughly 11.4 to 10.8 ka ( ∼  400 cm of core depth) is indicated by a sharp faunal change and unconformity or condensed zone of sedimentation. Regional sea level at this time was about 108 m b.s.l. at the 4-PC1 site and 102 m b.s.l. at 20-GC1. Regional sea level near the end of the YD was up to 42–47 m lower than predicted by geophysical models corrected for glacio-isostatic adjustment. This discrepancy could be explained by delayed isostatic adjustment caused by a greater volume and/or geographical extent of glacial-age land ice and/or ice shelves in the western Arctic Ocean and adjacent Siberian land areas.

Deglacial sea level history of the East Siberian Sea and Chukchi Sea margins

Directory of Open Access Journals (Sweden)

T. M. Cronin

2017-09-01

Full Text Available Deglacial (12.8–10.7 ka sea level history on the East Siberian continental shelf and upper continental slope was reconstructed using new geophysical records and sediment cores taken during Leg 2 of the 2014 SWERUS-C3 expedition. The focus of this study is two cores from Herald Canyon, piston core SWERUS-L2-4-PC1 (4-PC1 and multicore SWERUS-L2-4-MC1 (4-MC1, and a gravity core from an East Siberian Sea transect, SWERUS-L2-20-GC1 (20-GC1. Cores 4-PC1 and 20-GC were taken at 120 and 115 m of modern water depth, respectively, only a few meters above the global last glacial maximum (LGM;  ∼  24 kiloannum or ka minimum sea level of  ∼  125–130 meters below sea level (m b.s.l.. Using calibrated radiocarbon ages mainly on molluscs for chronology and the ecology of benthic foraminifera and ostracode species to estimate paleodepths, the data reveal a dominance of river-proximal species during the early part of the Younger Dryas event (YD, Greenland Stadial GS-1 followed by a rise in river-intermediate species in the late Younger Dryas or the early Holocene (Preboreal period. A rapid relative sea level rise beginning at roughly 11.4 to 10.8 ka ( ∼  400 cm of core depth is indicated by a sharp faunal change and unconformity or condensed zone of sedimentation. Regional sea level at this time was about 108 m b.s.l. at the 4-PC1 site and 102 m b.s.l. at 20-GC1. Regional sea level near the end of the YD was up to 42–47 m lower than predicted by geophysical models corrected for glacio-isostatic adjustment. This discrepancy could be explained by delayed isostatic adjustment caused by a greater volume and/or geographical extent of glacial-age land ice and/or ice shelves in the western Arctic Ocean and adjacent Siberian land areas.

The distribution of seabirds and fish in relation to ocean currents in the southeastern Chukchi Sea

Science.gov (United States)

Piatt, John F.; Wells, John L.; MacCharles, Andrea; Fadely, Brian S.; Montevecchi, W.A.; Gaston, A.J.

1991-01-01

In late August 1988, we studied the distribution of seabirds in the southeastern Chukchi Sea, particularly in waters near a major seabird colony at Cape Thompson. Foraging areas were characterized using hydrographic data obtained from hydroacoustic surveys for fish. Murres (Uria spp.) and Black-legged Kitttiwakes Rissa tridactyla breeding at Cape Thompson fed mostly on Arctic cod, which are known from previous studies to be the most abundant pelagic fish in the region. Our hydroacoustic surveys revealed that pelagic fish were distributed widely, but densities were estimated to be low (e.g., 0.1-10 g∙m-3) throughout the study area and a few schools were recorded. Large feeding flocks of murres and kittiwakes were observed over fish schools with densities estimated to exceed 15 g∙m-3. Fish densities were higher in shallow Alaska Coastal Current waters than offshore in Bering Sea waters, and most piscivorous seabirds foraged in coastal waters. Poor kittiwake breeding success and a low frequency of fish in murre and kittiwake stomachs in late August suggested that fish densities were marginal for sustaining breeding seabirds at that time. Planktivorous Least Auklets Aethia pusilla and Parakeet Auklets Cyclorrhynchus psittacula foraged almost exclusively in Bering Sea waters. Short-tailed Shearwaters Puffinus tenuirostris and Tufted Puffins Fratercula cirrhata foraged in transitional waters at the front between Coastal and Bering Sea currents.

Marine Fish and Shellfish Survey data from otter trawls in the Chukchi Sea from the OCEAN HOPE 3 and OSHORO MARU from 16 August 1990 to 31 July 1992 (NODC Accession 9400061)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Marine Fish and Shellfish Survey data were collected from otter trawls in the Chukchi Sea from the OCEAN HOPE. Data were collected by the University of Alaska from...

Ocean Profile Measurements During the Seasonal Ice Zone Reconnaissance Surveys Ocean Profiles

Science.gov (United States)

2017-01-01

converted to engineering units by the TSK Converter and recorded on the laptop computer . A backup recording of the raw received signal is made with...S, V, internal waves/mixing Clouds and the Evolution of the SIZ in Beaufort and Chukchi Seas Schweiger Lindsay, Zhang, Maslanik, Lawrence...Atmospheric profiles (dropsondes, micro-aircraft), cloud top/base heights UpTempO buoys for understanding and prediction…. Steele UpTempO buoy

Marine mammal observations collected by aircraft and ship and submitted as part of the ConocoPhillips and Shell Joint Monitoring Program in the Chukchi and Beaufort Seas, 2006-2007 (NODC Accession 0120531)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set was collected as part of the Joint Monitoring Program during seismic activities in the Chukchi Sea. The 2006 data was collected by ship and aircraft as...

Application of isostatic gravity anomaly in the Yellow Sea area

Science.gov (United States)

Hao, Z.; Qin, J.; Huang, W.; Wu, X.

2017-12-01

In order to study the deep crustal structure of the Yellow Sea area, we used the Airy-Heiskanen model to calculate the isostatic gravity anomaly of this area. Based on the Bouguer gravity anomaly and water depth data of this area, we chose the calculating parameters as standard crustal thickness 30 km, crust-mantle density difference 0.6g/cm3and grid spacing 0.1°×0.1°. This study reveals that there are six faults and four isostatic negative anomalies in the study area. The isostatic anomalies in much of Yellow Sea areas give priority to those with positive anomalies. The isostatic anomalies in North Yellow Sea are higher than South Yellow Sea with Jiashan-Xiangshui fault as the boundary. In the north of the study area, isostatic anomalies are characterized by large areas of positive anomaly. The change is relatively slow, and the trends give priority to the trend NE or NEE. In the middle of the north Yellow Sea basin, there is a local negative anomaly, arranged as a string of beads in NE to discontinuous distribution. Negative anomaly range is small, basically corresponds to the region's former Cenozoic sedimentary basin position. To the south of Jiashan-Xiangshui fault and west of Yellow Sea eastern margin fault, including most of the south Yellow Sea and Jiangsu province, the isostatic anomalies are lower. And the positive and negative anomalies are alternative distribution, and negative anomaly trap in extensive development. The trends give priority to NE, NEE, both to the NW. On the basis of the characteristics of isostatic gravity anomalies, it is concluded that the Yellow Sea belongs to continental crustal isostatic area whose isostatic anomalies is smooth and slow. ReferencesHeiskanen, W. A., F. A. V. Meinesz, and S. A. Korff (1958), The Earth and Its Gravity Field, McGraw-Hill, New York. Meng, X. J., X. H. Zhang, and J. Y. Yang (2014), Geophysical survey in eastern China seas and the characteristics of gravity and magnetic fields, Marine Geoglogy

Acoustics short-term passive monitoring using sonobuoys in the Bering, Chukchi, and Western Beaufort Seas conducted by Alaska Fisheries Scientific Center, National Marine Mammal Laboratory from 2007-08-01 to 2015-09-28 (NCEI Accession 0138863)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The National Marine Mammal Laboratory (NMML) has conducted passive acoustic monitoring in the Bering, Chukchi, and Western Beaufort Seas to determine spatio-temporal...

Benthic Community Composition and Seabed Characteristics of a Chukchi Sea Pockmark

Science.gov (United States)

MacDonald, I. R.; Bluhm, B.; Iken, K.; Gagaev, S.; Robinson, S.

2005-12-01

Several dozen seafloor features were mapped by Larry Mayer and his colleagues using swath bathymetry during a 2003 cruise with the USCGC HEALY near the eastern edge of the Chukchi Plateau (Chukchi Sea 76.6N, 163.9W). These were sub-circular depressions ranging from approximately 250 to over 1000m in width, with depths of up to 50m below the surrounding seabed, and situated in water depths from 500 to 950m. The origin of these features was undetermined, but one possibility was that they were pockmarks formed as a result of gas or fluid expulsion processes. We report here on benthic sampling undertaken at one of these pockmarks on 18 July 2005, also from USCGC HEALY. This elongated feature had maximum water depth of approximately 940m, was 1200m in maximum width, and was depressed approximately 40m below the surrounding seabed. The ocean in the vicinity of the pockmark was heavily ice-covered, which tightly restricted the ship's mobility during sampling operations. We used an ROV to collect and photograph the benthic epifauna during a 6h transit that crossed from the outside of the pockmark to near the center over a distance of 900m. We used a down-looking digital camera to collect over 800 pictures of the benthos at altitudes of 2 to 3m above the seabed. We also collected three cores with a 25x25cm box corer. Our investigations did not provide any direct evidence for gas or fluid flux through the seabed of this feature. Neither did we see any secondary indications of methane flux such as authigenic carbonates or bacterial mats. The abundance and diversity of benthic epifauna at this station was the highest among 8 stations sampled using similar methods during a 30 day cruise. The ROV observed brittle stars, various types of anemones, shrimps, eel pouts, stalked crinoids, benthic ctenophore (likely new species), burrows and mounts, gooseneck barnacles, mysids. Holothurians (c.f. Peneagone sp.) were the single most abundant group and were often photographed in

Potential impacts of offshore oil spills on polar bears in the Chukchi Sea.

Science.gov (United States)

Wilson, Ryan R; Perham, Craig; French-McCay, Deborah P; Balouskus, Richard

2018-04-01

Sea ice decline is anticipated to increase human access to the Arctic Ocean allowing for offshore oil and gas development in once inaccessible areas. Given the potential negative consequences of an oil spill on marine wildlife populations in the Arctic, it is important to understand the magnitude of impact a large spill could have on wildlife to inform response planning efforts. In this study we simulated oil spills that released 25,000 barrels of oil for 30 days in autumn originating from two sites in the Chukchi Sea (one in Russia and one in the U.S.) and tracked the distribution of oil for 76 days. We then determined the potential impact such a spill might have on polar bears (Ursus maritimus) and their habitat by overlapping spills with maps of polar bear habitat and movement trajectories. Only a small proportion (1-10%) of high-value polar bear sea ice habitat was directly affected by oil sufficient to impact bears. However, 27-38% of polar bears in the region were potentially exposed to oil. Oil consistently had the highest probability of reaching Wrangel and Herald islands, important areas of denning and summer terrestrial habitat. Oil did not reach polar bears until approximately 3 weeks after the spills. Our study found the potential for significant impacts to polar bears under a worst case discharge scenario, but suggests that there is a window of time where effective containment efforts could minimize exposure to bears. Our study provides a framework for wildlife managers and planners to assess the level of response that would be required to treat exposed wildlife and where spill response equipment might be best stationed. While the size of spill we simulated has a low probability of occurring, it provides an upper limit for planners to consider when crafting response plans. Published by Elsevier Ltd.

Decadal shifts in autumn migration timing by Pacific Arctic beluga whales are related to delayed annual sea ice formation.

Science.gov (United States)

Hauser, Donna D W; Laidre, Kristin L; Stafford, Kathleen M; Stern, Harry L; Suydam, Robert S; Richard, Pierre R

2017-06-01

Migrations are often influenced by seasonal environmental gradients that are increasingly being altered by climate change. The consequences of rapid changes in Arctic sea ice have the potential to affect migrations of a number of marine species whose timing is temporally matched to seasonal sea ice cover. This topic has not been investigated for Pacific Arctic beluga whales (Delphinapterus leucas) that follow matrilineally maintained autumn migrations in the waters around Alaska and Russia. For the sympatric Eastern Chukchi Sea ('Chukchi') and Eastern Beaufort Sea ('Beaufort') beluga populations, we examined changes in autumn migration timing as related to delayed regional sea ice freeze-up since the 1990s, using two independent data sources (satellite telemetry data and passive acoustics) for both populations. We compared dates of migration between 'early' (1993-2002) and 'late' (2004-2012) tagging periods. During the late tagging period, Chukchi belugas had significantly delayed migrations (by 2 to >4 weeks, depending on location) from the Beaufort and Chukchi seas. Spatial analyses also revealed that departure from Beaufort Sea foraging regions by Chukchi whales was postponed in the late period. Chukchi beluga autumn migration timing occurred significantly later as regional sea ice freeze-up timing became later in the Beaufort, Chukchi, and Bering seas. In contrast, Beaufort belugas did not shift migration timing between periods, nor was migration timing related to freeze-up timing, other than for southward migration at the Bering Strait. Passive acoustic data from 2008 to 2014 provided independent and supplementary support for delayed migration from the Beaufort Sea (4 day yr -1 ) by Chukchi belugas. Here, we report the first phenological study examining beluga whale migrations within the context of their rapidly transforming Pacific Arctic ecosystem, suggesting flexible responses that may enable their persistence yet also complicate predictions of how

The gravity field of the Red Sea and East Africa

Science.gov (United States)

Makris, Jannis; Henke, Christian H.; Egloff, Frank; Akamaluk, Thomas

1991-11-01

Reevaluation of all gravity data from the Red Sea, the Gulf of Aden and East Africa permitted the compilation of a new Bouguer anomaly map. The intensity of the gravity field and its regional pattern correlate closely with the topographic features of the region. The maximum Bouguer values (> + 100 mGal) are located over the median troughs of the Red Sea and Gulf of Aden. Dense juvenile oceanic crust in these rifts and intruding magmas in stretched continental areas produce excess mass responsible for the anomaly highs. In the Red Sea the orientation of the gravity highs is NW-SE in the south, turning to NE-SW in the north, almost parallel to the Aqaba-Dead Sea strike. This pattern reveals that the present basin axis is not identical with that which formed the Tertiary coastal margins and the pre-Red Sea zones of crustal weakness. In the Gulf of Aden, new oceanic crust along the Tadjura Trench and its eastward extension is also expressed in the Bouguer anomaly map by gravity highs and a sharp bending of the isolines. A maximum of approx. +150 mGal is located over the central section of the Sheba Ridge. Bouguer gravity values over the East African and Yemen Plateaus are of the order of -180 to -240 mGal, indicating significant crustal thickening. On the Somali Plateau, the Marda Fault also has a strong gravity signature that can be traced towards Somalia. By constraining crustal thickness and structure with seismic data and density values from the velocity distribution by means of the Nafe-Drake and Birch relationships, we computed density models for the crust and upper mantle. The crustal thickness is of the order of 40 km beneath the plateaus and only 5 to 6 km at the oceanized parts in the central and southern portions of the Red Sea median trough. The flanks of the southern Red Sea and the corresponding Arabian side are underlain by 12 to 16 km thick stretched continental type crust. Oceanization offshore Sudan and Egypt is asymmetrical. The continental crust

Gravity field modeling at the sea areas using satellite altimetry observations Case study: Gravity field modeling at the Coastal Fars

International Nuclear Information System (INIS)

Jomegi, A.

2007-01-01

Nowadays, satellite altimetry observations had made it possible to determine sea surface variations, in the global scale, to high degree of precision. Using satellite altimetry observations, Mean Sea Level (MSL) can be determined, which by Kowing Sea Surface Topography (SST), can be converted into high-resolution marine geoid. In this paper we are proposing a method for computation of the Earth's gravity field at the sea areas, which is different from usual methods. Indeed, our method is based on conversion of geoidal heights into gravity potential values at the reference ellipsoid 2 Ea,b , by using ellipsoidal Brun's formula, and forward application of solution of Fixed-Free Two Boundary Value Problem (FFTBVP), previously proposed by the authors for the geoid computations without application of Stokes formula. Numerical results of application of the proposed method at the test area of CoastalFars (at southern part of Iran) show the success of the method. Considering the low cost and high precision of satellite altimetry observations, the proposed method suggests an efficient substitution to shipborne gravity observations for gravity field molding at the sea areas

Seasonal to Mesoscale Variability of Water Masses in Barrow Canyon,Chukchi Sea

Science.gov (United States)

Nobre, C.; Pickart, R. S.; Moore, K.; Ashjian, C. J.; Arrigo, K. R.; Grebmeier, J. M.; Vagle, S.; Itoh, M.; Berchok, C.; Stabeno, P. J.; Kikuchi, T.; Cooper, L. W.; Hartwell, I.; He, J.

2016-02-01

Barrow Canyon is one of the primary conduits by which Pacific-origin water exits the Chukchi Sea into the Canada Basin. As such, it is an ideal location to monitor the different water masses through the year. At the same time, the canyon is an energetic environment where mixing and entrainment can occur, modifying the pacific-origin waters. As part of the Distributed Biological Observatory (DBO) program, a transect across the canyon was occupied 24 times between 2010-2013 by international ships of opportunity passing through the region during summer and early-fall. Here we present results from an analysis of these sections to determine the seasonal evolution of the water masses and to investigate the nature of the mesoscale variability. The mean state shows the clear presence of six water masses present at various times through the summer. The seasonal evolution of these summer water masses is characterized both in depth space and in temperature-salinity (T-S) space. Clear patterns emerge, including the arrival of Alaskan coastal water and its modification in early-fall. The primary mesoscale variability is associated with wind-driven upwelling events which occur predominantly in September. The atmospheric forcing of these events is investigated as is the oceanic response.

Ice loading model for Glacial Isostatic Adjustment in the Barents Sea constrained by GRACE gravity observations

Science.gov (United States)

Root, Bart; Tarasov, Lev; van der Wal, Wouter

2014-05-01

The global ice budget is still under discussion because the observed 120-130 m eustatic sea level equivalent since the Last Glacial Maximum (LGM) can not be explained by the current knowledge of land-ice melt after the LGM. One possible location for the missing ice is the Barents Sea Region, which was completely covered with ice during the LGM. This is deduced from relative sea level observations on Svalbard, Novaya Zemlya and the North coast of Scandinavia. However, there are no observations in the middle of the Barents Sea that capture the post-glacial uplift. With increased precision and longer time series of monthly gravity observations of the GRACE satellite mission it is possible to constrain Glacial Isostatic Adjustment in the center of the Barents Sea. This study investigates the extra constraint provided by GRACE data for modeling the past ice geometry in the Barents Sea. We use CSR release 5 data from February 2003 to July 2013. The GRACE data is corrected for the past 10 years of secular decline of glacier ice on Svalbard, Novaya Zemlya and Frans Joseph Land. With numerical GIA models for a radially symmetric Earth, we model the expected gravity changes and compare these with the GRACE observations after smoothing with a 250 km Gaussian filter. The comparisons show that for the viscosity profile VM5a, ICE-5G has too strong a gravity signal compared to GRACE. The regional calibrated ice sheet model (GLAC) of Tarasov appears to fit the amplitude of the GRACE signal. However, the GRACE data are very sensitive to the ice-melt correction, especially for Novaya Zemlya. Furthermore, the ice mass should be more concentrated to the middle of the Barents Sea. Alternative viscosity models confirm these conclusions.

Sedimentation Deposition Patterns on the Chukchi Shelf Using Radionuclide Inventories

Science.gov (United States)

Cooper, L. W.; Grebmeier, J. M.

2016-02-01

Sediment core collections and assays of the anthropogenic and natural radioisotopes, 137Cs and 210Pb, respectively, are providing long-term indications of sedimentation and current flow processes on the Chukchi and East Siberian sea continental shelf. This work, which has been integrated into interdisciplinary studies of the Chukchi Sea supported by both the US Bureau of Ocean Energy Management (COMIDA Hanna Shoal Project) and the National Oceanic and Atmospheric Administration (Russian-US Long Term Census of the Arctic, RUSALCA) includes studies of total radiocesium inventories, sedimentation rate determinations, where practical, and depths of maxima in radionuclide deposition. Shallow maxima in the activities of the anthropogenic radionuclide in sediment cores reflect areas with higher current flow (Barrow Canyon and Herald Canyon; 3-6 cm) or low sedimentation (Hanna Shoal; 1-3 cm). The first sedimentation studies from Long Strait are consistent with quiescent current conditions and steady recent sedimentation of clay particles. Elsewhere, higher and more deeply buried radionuclide inventories (> 2 mBq cm-2 at 15-17 cm depth) in the sediments correspond to areas of high particle deposition north of Bering Strait where bioturbation in productive sediments is also clearly an important influence. Radiocesium activities from bomb fallout dating to 1964 are now present at low levels (20 cm. Independent sedimentation rate measurements with the natural radionuclide 210Pb are largely consistent with the radiocesium measurements.

Airborne gravity survey of Lincoln Sea and Wandel Sea, north Greenland

DEFF Research Database (Denmark)

Olesen, Arne Vestergaard; Forsberg, René; Keller, K.

2000-01-01

In June 1998 National Survey and Cadastre Denmark (KMS) carried out an airborne gravity survey over the Polar Sea to the north of Greenland. A Twin Otter from Greenlandair, equipped with autopilot and additional fuel tanks, was employed for the survey. A modified marine LaCoste & Romberg gravimet...

Holocene Paleoceanographic Environments at the Chukchi-Alaskan Margin: Implications for Future Changes

Science.gov (United States)

Polyak, L.; Nam, S. I.; Dipre, G.; Kim, S. Y.; Ortiz, J. D.; Darby, D. A.

2017-12-01

The impacts of the North Pacific oceanic and atmospheric system on the Arctic Ocean result in accelerated sea-ice retreat and related changes in hydrography and biota in the western Arctic. Paleoclimatic records from the Pacific sector of the Arctic are key for understanding the long-term history of these interactions. As opposed to stratigraphically long but strongly compressed sediment cores recovered from the deep Arctic Ocean, sediment depocenters on the Chukchi-Alaskan margin yield continuous, medium to high resolution records formed since the last deglaciation. While early Holocene conditions were non-analogous to modern environments due to the effects of prolonged deglaciation and insufficiently high sea levels, mid to late Holocene sediments are more relevant for recent and modern climate variability. Notably, a large depocenter at the Alaskan margin has sedimentation rates estimated as high as a few millimeters per year, thus providing a decadal to near-annual resolution. This high accumulation can be explained by sediment delivery via the Alaskan Coastal Current originating from the Bering Sea and supposedly controlled by the Aleutian Low pressure center. Preliminary results from sediment cores recovering the last several centuries, along with a comparison with other paleoclimatic proxy records from the Arctic-North Pacific region, indicate a persistent role of the Aleutian Low in the Bering Strait inflow and attendant deposition. More proxy studies are underway to reconstruct the history of this circulation system and its relationship with sea ice extent. The expected results will improve our understanding of natural variability in oceanic and atmospheric conditions at the Chukchi-Alaskan margin, a critical area for modulating the Arctic climate change.

Distribution and air-sea exchange of current-use pesticides (CUPs) from East Asia to the high Arctic Ocean.

Science.gov (United States)

Zhong, Guangcai; Xie, Zhiyong; Cai, Minghong; Möller, Axel; Sturm, Renate; Tang, Jianhui; Zhang, Gan; He, Jianfeng; Ebinghaus, Ralf

2012-01-03

Surface seawater and marine boundary layer air samples were collected on the ice-breaker R/V Xuelong (Snow Dragon) from the East China Sea to the high Arctic (33.23-84.5° N) in July to September 2010 and have been analyzed for six current-use pesticides (CUPs): trifluralin, endosulfan, chlorothalonil, chlorpyrifos, dacthal, and dicofol. In all oceanic air samples, the six CUPs were detected, showing highest level (>100 pg/m(3)) in the Sea of Japan. Gaseous CUPs basically decreased from East Asia (between 36.6 and 45.1° N) toward Bering and Chukchi Seas. The dissolved CUPs in ocean water ranged widely from air. Trifluralin in seawater was relatively high in the Sea of Japan (35.2° N) and evenly distributed between 36.9 and 72.5° N, but it remained below the detection limit at the highest northern latitudes in Chukchi Sea. In contrast with other CUPs, concentrations of chlorothalonil and dacthal were more abundant in Chukchi Sea and in East Asia. The air-sea gas exchange of CUPs was generally dominated by net deposition. Latitudinal trends of fugacity ratios of α-endosulfan, chlorothalonil, and dacthal showed stronger deposition of these compounds in East Asia than in Chukchi Sea, while trifluralin showed stronger deposition in Chukchi Sea (-455 ± 245 pg/m(2)/day) than in the North Pacific (-241 ± 158 pg/m(2)/day). Air-sea gas exchange of chlorpyrifos varied from net volatilizaiton in East Asia (<40° N) to equilibrium or net deposition in the North Pacific and the Arctic.

Mooring-based long-term observation of oceanographic condition in the Chukchi Ses and Canada Basin of the Arctic Ocean

Science.gov (United States)

Kikuchi, Takashi; Itoh, Motoyo; Nishino, Shigeto; Watanabe, Eiji

2015-04-01

Changes of the Arctic Ocean environment are well known as one of the most remarkable evidences of global warming, attracting social and public attentions as well as scientists'. However, to illustrate on-going changes and predict future condition of the Arctic marine environment, we still do not have enough knowledge of Arctic sea ice and marine environment. In particular, lack of observation data in winter, e.g., under sea ice, still remains a key issue for precise understanding of seasonal cycle on oceanographic condition in the Arctic Ocean. Mooring-based observation is one of the most useful methods to collect year-long data in the Arctic Ocean. We have been conducting long-term monitoring using mooring system in the Pacific sector of the Arctic Ocean. Volume, heat, and freshwater fluxes through Barrow Canyon where is a major conduit of Pacific-origin water-masses into the Canada Basin have been observed since 2000. We show from an analysis of the mooring results that volume flux through Barrow Canyon was about 60 % of Bering Strait volume flux. Averaged heat flux ranges from 0.9 to 3.07 TW, which could melt 88,000 to 300,000 km2 of 1m thick ice in the Canada Basin, which likely contributed to sea ice retreat in the Pacific sector of the Arctic Ocean. In winter, we found inter-annual variability in salinity related to coastal polynya activity in the Chukchi Sea. In collaboration with Distributed Biological Observatory (DBO) project, which is one of the tasks of Sustaining Arctic Observing Network (SAON), we also initiated year-long mooring observation in the Hope Valley of the southern Chukchi Sea since 2012. Interestingly, winter oceanographic conditions in the Hope Valley are greatly different between in 2012-2013 and in 2013-2014. We speculate that differences of sea ice freeze-up and coastal polynya activity in the southern Chukchi Sea cause significant difference of winter oceanographic condition. It suggests that recent sea ice reduction in the Pacific

Trends in Sea Ice Cover, Sea Surface Temperature, and Chlorophyll Biomass Across a Marine Distributed Biological Observatory in the Pacific Arctic Region

Science.gov (United States)

Frey, K. E.; Grebmeier, J. M.; Cooper, L. W.; Wood, C.; Panday, P. K.

2011-12-01

The northern Bering and Chukchi Seas in the Pacific Arctic Region (PAR) are among the most productive marine ecosystems in the world and act as important carbon sinks, particularly during May and June when seasonal sea ice-associated phytoplankton blooms occur throughout the region. Recent dramatic shifts in seasonal sea ice cover across the PAR should have profound consequences for this seasonal phytoplankton production as well as the intimately linked higher trophic levels. In order to investigate ecosystem responses to these observed recent shifts in sea ice cover, the development of a prototype Distributed Biological Observatory (DBO) is now underway in the PAR. The DBO is being developed as an internationally-coordinated change detection array that allows for consistent sampling and monitoring at five spatially explicit biologically productive locations across a latitudinal gradient: (1) DBO-SLP (south of St. Lawrence Island (SLI)), (2) DBO-NBS (north of SLI), (3) DBO-SCS (southern Chukchi Sea), (4) DBO-CCS (central Chukchi Sea), and (5) DBO-BCA (Barrow Canyon Arc). Standardized measurements at many of the DBO sites were made by multiple research cruises during the 2010 and 2011 pilot years, and will be expanded with the development of the DBO in coming years. In order to provide longer-term context for the changes occurring across the PAR, we utilize multi-sensor satellite data to investigate recent trends in sea ice cover, chlorophyll biomass, and sea surface temperatures for each of the five DBO sites, as well as a sixth long-term observational site in the Bering Strait. Satellite observations show that over the past three decades, trends in sea ice cover in the PAR have been heterogeneous, with significant declines in the Chukchi Sea, slight declines in the Bering Strait region, but increases in the northern Bering Sea south of SLI. Declines in the persistence of seasonal sea ice cover in the Chukchi Sea and Bering Strait region are due to both earlier sea

Partial pressure (or fugacity) of carbon dioxide, salinity and sea surface temperature collected from Surface underway observations using Carbon dioxide (CO2) gas analyzer, Shower head chamber equilibrator for autonomous carbon dioxide (CO2) measurement and other instruments during R/V Oden cruise Beringia_2005 (EXPOCODE 77DN20050720) in the Northwest Passage, Can. Archipelago, Bering Strait, Chukchi Sea, East Siberian Sea and Arctic Ocean from 2005-07-20 to 2005-08-17 (NCEI Accession 0164210)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0164210 includes Surface underway data collected from R/V Oden in the Northwest Passage, Can. Archipelago, Bering Strait, Chukchi Sea, East Siberian...

Distribution and sources of polycyclic aromatic hydrocarbons in surface sediments from the Bering Sea and western Arctic Ocean.

Science.gov (United States)

Zhao, Mengwei; Wang, Weiguo; Liu, Yanguang; Dong, Linsen; Jiao, Liping; Hu, Limin; Fan, Dejiang

2016-03-15

To analyze the distribution and sources of polycyclic aromatic hydrocarbons (PAHs) and evaluate their potential ecological risks, the concentrations of 16 PAHs were measured in 43 surface sediment samples from the Bering Sea and western Arctic Ocean. Total PAH (tPAH) concentrations ranged from 36.95 to 150.21 ng/g (dry weight). In descending order, the surface sediment tPAH concentrations were as follows: Canada Basin>northern Chukchi Sea>Chukchi Basin>southern Chukchi Sea>Aleutian Basin>Makarov Basin>Bering Sea shelf. The Bering Sea and western Arctic Ocean mainly received PAHs of pyrogenic origin due to pollution caused by the incomplete combustion of fossil fuels. The concentrations of PAHs in the sediments of the study areas did not exceed effects range low (ERL) values. Copyright © 2016 Elsevier Ltd. All rights reserved.

Atmospheric gravity waves in the Red Sea: a new hotspot

KAUST Repository

Magalhaes, J. M.

2011-02-03

The region of the Middle East around the Red Sea (between 32° E and 44° E longitude and 12° N and 28° N latitude) is a currently undocumented hotspot for atmospheric gravity waves (AGWs). Satellite imagery shows evidence that this region is prone to relatively high occurrence of AGWs compared to other areas in the world, and reveals the spatial characteristics of these waves. The favorable conditions for wave propagation in this region are illustrated with three typical cases of AGWs propagating in the lower troposphere over the sea. Using weakly nonlinear long wave theory and the observed characteristic wavelengths we obtain phase speeds which are consistent with those observed and typical for AGWs, with the Korteweg-de Vries theory performing slightly better than Benjamin-Davis-Acrivos-Ono theory as far as phase speeds are concerned. ERS-SAR and Envisat-ASAR satellite data analysis between 1993 and 2008 reveals signatures consistent with horizontally propagating large-scale internal waves. These signatures cover the entire Red Sea and are more frequently observed between April and September, although they also occur during the rest of the year. The region\\'s (seasonal) propagation conditions for AGWs, based upon average vertical atmospheric stratification profiles suggest that many of the signatures identified in the satellite images are atmospheric internal waves. © Author(s) 2011.

Landfast sea ice break-out events in the Chukchi Sea: Two case studies illuminating long-term observations at Barrow, Alaska

Science.gov (United States)

Jones, J.; Eicken, H.; Mahoney, A. R.; Mv, R.; Kambhamettu, C.; Fukamachi, Y.; Ohshima, K. I.

2012-12-01

Landfast sea ice in northern Alaska is an important coastal feature. It protects coasts from the impacts of storms, acts as a platform for travel and subsistence activities by native communities, and can be an obstacle to near-shore maritime enterprise. These services provided by landfast ice depend upon its presence and extent, as well as the ice cover's capacity to remain stably in place for long periods of time during the ice season. Along the eastern Chukchi coast and specifically at Barrow, Alaska, the near-shore ice conditions are highly dynamic. In recent years, break-outs of the landfast ice have been observed at Barrow, removing larger stretches of previously immobile landfast ice from shore and potentially threatening people and equipment. Indigenous knowledge by local Iñupiaq ice experts extending back several decades indicates that such events were rare or absent until the 1990s. Using imagery from a land-based marine radar, a component of the Barrow Sea Ice Observatory of the University of Alaska Fairbanks, landfast ice formation at Barrow, AK, has been tracked each season since 2005, and a number of break-out events have been identified. A detailed analysis of atmospheric, oceanic and sea ice conditions associated with such events can shed light on local knowledge and understanding of such events, and help develop approaches to predict and respond to break-outs. Here, two break-out events (on February 27, 2009 and March 24, 2010) are the subjects of case studies aimed at determining primary causes of break-outs. The radar imagery is used to track near-shore ice deformation prior to the break-out and to estimate the extent of grounded sea ice ridges. Oceanic and atmospheric data are used to estimate current and wind stress on the landfast ice cover. Sea level measurements provide insight as to whether or not a grounded ridge's keel could be lifted out of its bed, a potential precondition for a break-out to occur. Preliminary results suggest different

The Crustal Thickness of the Philippine Sea Plate Derived from Gravity Data

Directory of Open Access Journals (Sweden)

Horng-Yuan Yen

2015-01-01

Full Text Available We constructed a new free-air gravity anomaly map of the Philippine Sea Plate (PSP using ship-tracked gravity data from the National Geophysical Data Center (NGDC. Our results show that the isogals trend correlates well with the tectonic structures in the PSP. After removing the gravity induced by sea water from the free-air gravity data, we obtained the regional Bouguer gravity anomaly, which is later used to compute the Moho geometry in the PSP by applying the Parker-Oldenburg iterative method. Our results indicate that in the southern part of the West Philippine Basin (WPB the crustal thickness is nearly homogeneous with a value of about 5 km, which implies that the WPB is quite stable. The low-amplitude and near-zero free-air gravity anomalies clearly indicate that the whole WPB, except at trenches and island arcs, is nearly in a state of isostatic equilibrium. The average crustal thickness of the Palau Kyushu Ridge (PKR is more than 10 km. In the eastern PSP the crustal thickness gradually increases eastward. Our results also imply that a relatively thin and low density mantle exists beneath the Parece Vela Basin (PVB as a consequence of back-arc spreading and serpentinized upwells of the thin crustal thickness.

Arctic Ocean gravity, geoid and sea-ice freeboard heights from ICESat and GRACE

DEFF Research Database (Denmark)

Forsberg, René; Skourup, Henriette

2005-01-01

Gravity Project in combination with GRACE gravity field models to derive an improved Arctic geoid model. This model is then used to convert ICESat measurements to sea-ice freeboard heights with a coarse lowest-level surface method. The derived freeboard heights show a good qualitative agreement...... all major tectonic features of the Arctic Ocean, and has an accuracy of 6 mGal compared to recent airborne gravity data, illustrating the usefulness of ICESat data for gravity field determination....

Assessing the potential impacts of declining Arctic sea ice cover on the photochemical degradation of dissolved organic matter in the Chukchi and Beaufort Seas

Science.gov (United States)

Logvinova, Christie L.; Frey, Karen E.; Mann, Paul J.; Stubbins, Aron; Spencer, Robert G. M.

2015-11-01

A warming and shifting climate in the Arctic has led to significant declines in sea ice over the last several decades. Although these changes in sea ice cover are well documented, large uncertainties remain in how associated increases in solar radiation transmitted to the underlying ocean water column will impact heating, biological, and biogeochemical processes in the Arctic Ocean. In this study, six under-ice marine, two ice-free marine, and two ice-free terrestrially influenced water samples were irradiated using a solar simulator for 72 h (representing ~10 days of ambient sunlight) to investigate dissolved organic matter (DOM) dynamics from the Chukchi and Beaufort Seas. Solar irradiation caused chromophoric DOM (CDOM) light absorption at 254 nm to decrease by 48 to 63%. An overall loss in total DOM fluorescence intensity was also observed at the end of all experiments, and each of six components identified by parallel factor (PARAFAC) analysis was shown to be photoreactive in at least one experiment. Fluorescent DOM (FDOM) also indicated that the majority of DOM in under-ice and ice-free marine waters was likely algal-derived. Measurable changes in dissolved organic carbon (DOC) were only observed for sites influenced by riverine runoff. Losses of CDOM absorbance at shorter wavelengths suggest that the beneficial UV protection currently received by marine organisms may decline with the increased light transmittance associated with sea ice melt ponding and overall reductions of sea ice. Our FDOM analyses demonstrate that DOM irrespective of source was susceptible to photobleaching. Additionally, our findings suggest that photodegradation of CDOM in under-ice waters is not currently a significant source of carbon dioxide (CO2) (i.e., we did not observe systematic DOC loss). However, increases in primary production and terrestrial freshwater export expected under future climate change scenarios may cause an increase in CDOM quantity and shift in quality

Chukchi Borderland | Crustal Complex of the Amerasia Basin, Arctic Ocean

Science.gov (United States)

Ilhan, I.; Coakley, B.; Houseknecht, D. W.

2017-12-01

In the Arctic Ocean, Chukchi Borderland separates the North Chukchi shelf and Toll deep basins to the west and Canada deep basin to the east. Existing plate reconstructions have attempted to restore this north-striking, fragments of the continental crust to all margins of the Amerasia Basin based on sparse geologic and geophysical measurements. Regional multi-channel seismic reflection and potential field geophysics, and geologic data indicate it is a high standing continental block, requiring special accommodation to create a restorable model of the formation of the Amerasia Basin. The Borderland is composed of the Chukchi Plateau, Northwind Basin, and Northwind Ridge divided by mostly north striking normal faults. These offset the basement and bound a sequence of syn-tectonic sediments. Equivalent strata are, locally, uplifted, deformed and eroded. Seaward dipping reflectors (SDRs) are observed in the juncture between the North Chukchi, Toll basins, and southern Chukchi Plateau underlying a regional angular unconformity. This reveals that this rifted margin was associated with volcanism. An inferred condensed section, which is believed to be Hauterivian-Aptian in age, synchronous with the composite pebble shale and gamma-ray zone of the Alaska North Slope forms the basal sediments in the North Chukchi Basin. Approximately 15 km of post-rift strata onlap the condensed section, SDRs and, in part, the wedge sequence on the Chukchi Plateau from west to east, thinning to the north. These post-Aptian sediments imply that the rifted margin subsided no later than the earliest Cretaceous, providing a plausible time constraint for the inferred pre-Cretaceous rifting in this region. The recognition of SDRs and Hauterivian—Aptian condensed section, and continuity of the Early—Late Cretaceous post-rift strata along the margins of the Borderland, strike variations of the normal faults, absence of observable deformation along the Northwind Escarpment substantially constrain

Constraining Earth's Rheology of the Barents Sea Using Grace Gravity Change Observations

Science.gov (United States)

van der Wal, W.; Root, B. C.; Tarasov, L.

2014-12-01

The Barents Sea region was ice covered during last glacial maximum and experiences Glacial Isostatic Adjustment (GIA). Because of the limited amount of relevant geological and geodetic observations, it is difficult to constrain GIA models for this region. With improved ice sheet models and gravity observations from GRACE, it is possible to better constrain Earth rheology. This study aims to constrain the upper mantle viscosity and elastic lithosphere thickness from GRACE data in the Barents Sea region. The GRACE observations are corrected for current ice melting on Svalbard, Novaya Zemlya and Frans Joseph Land. A secular trend in gravity rate trend is estimated from the CSR release 5 GRACE data for the period of February 2003 to July 2013. Furthermore, long wavelength effects from distant large mass balance signals such as Greenland ice melting are filtered out. A new high-variance set of ice loading histories from calibrated glaciological modeling are used in the GIA modeling as it is found that ICE-5G over-estimates the observed GIA gravity change in the region. It is found that the rheology structure represented by VM5a results in over-estimation of the observed gravity change in the region for all ice sheet chronologies investigated. Therefore, other rheological Earth models were investigated. The best fitting upper mantle viscosity and elastic lithosphere thickness in the Barents Sea region are 4 (±0.5)*10^20 Pas and 110 (±20) km, respectively. The GRACE satellite mission proves to be a useful constraint in the Barents Sea Region for improving our knowledge on the upper mantle rheology.

Variation of the gravity acceleration with the latitude and altitude

Directory of Open Access Journals (Sweden)

Wilson Lopes

2009-01-01

Full Text Available The propose of this work is an equation for the module of the acceleration vector of the gravity, varying with the latitude and altitude. For this purpose, the following values of the gravity acceleration were used, at the sea level: in the equator, g0 = 9,7803 m/s2, and in the latitude of 450, gP = 9,8062 m/s2. The terrestrial profile were assumed as being a revolution ellipsoid, flattened in the poles, and the acceleration of the gravity varying with the altitude, at sea level, was considered dependent of the latitude too.

Principal facts of gravity stations with gravity and magnetic profiles from the southwest Nevada Test Site, Nye County, Nevada, as of January 1982

International Nuclear Information System (INIS)

Jansma, P.E.; Snyder, D.B.; Ponce, D.A.

1983-01-01

Three gravity profiles and principal facts of 2604 gravity stations in the southwest quadrant of the Nevada Test Site are documented in this data report. The residual gravity profiles show the gravity measurements and the smoothed curves derived from these points that were used in geophysical interpretations. The principal facts include station label, latitude, longitude, elevation, observed gravity value, and terrain correction for each station as well as the derived complete Bouguer and isostatic anomalies, reduced at 2.67 g/cm 3 . Accuracy codes, where available, further document the data

Atmospheric gravity waves in the Red Sea: a new hotspot

KAUST Repository

Magalhaes, J. M.; Araú jo, I. B.; da Silva, J. C. B.; Grimshaw, R. H. J.; Davis, K.; Pineda, J.

2011-01-01

The region of the Middle East around the Red Sea (between 32° E and 44° E longitude and 12° N and 28° N latitude) is a currently undocumented hotspot for atmospheric gravity waves (AGWs). Satellite imagery shows evidence that this region is prone

Aerial surveys of endangered whales in the Alaskan Chukchi and western Beaufort Seas, 1990. Final report, Oct-Nov 90

International Nuclear Information System (INIS)

Moore, S.E.; Clarke, J.T.

1991-06-01

In keeping with the National Environmental Policy Act (1969), the Marine Mammal Protection Act (1972) and the Endangered Species Act (1973), the OCS Lands Act Amendments (1978) established a management policy that included studies in OCS lease sale areas to ascertain potential environmental impacts of oil and gas development on OCS marine coastal environments. The Minerals Management Service (MMS) is the agency responsible for these studies and for the leasing of submerged Federal lands. The report summarizes the 1990 investigations of the distribution, abundance, migration, behavior and habitat relationships of endangered whales in the Alaskan Chukchi and western Beaufort Seas (hereafter, study area); 1990 was the second of a three year (1989-91) study. The Bering Sea stock of bowhead whales (Balaena mysticetus) was the principal species studied, with incidental sightings of all other marine mammals routinely recorded. The 1990 season was compromised by circumstances that restricted the availability of the survey aircraft (Grumman Goose, model G21G) to the period 26 October - 7 November; opportunistic surveys were flown in the study area from 3-25 October. In 1990, there were 14 sightings of 19 bowheads from 9-29 October; 5 whales, including 2 calves, were seen north of the study area. One gray whale, 110 belukhas and 53 polar bears were also seen. Over nine survey seasons (1982-90), there were 240 sightings of 520 bowhead whales and 148 sightings of 398 gray whales

A 3D gravity and magnetic model for the Entenschnabel area (German North Sea)

Science.gov (United States)

Dressel, Ingo; Barckhausen, Udo; Heyde, Ingo

2018-01-01

In this study, we focus on structural configuration of the Entenschnabel area, a part of the German exclusive economic zone within the North Sea, by means of gravity and magnetic modelling. The starting point of the 3D modelling approach is published information on subseafloor structures for shallow depths, acquired by wells and seismic surveys. Subsequent gravity and magnetic modelling of the structures of the deeper subsurface builds on this geophysical and geological information and on gravity and magnetic data acquired during a research cruise to the Entenschnabel area. On the one hand, our 3D model shows the density and susceptibility distribution of the sediments and the crust. In addition, the potential field modelling provides evidence for a differentiation between lower and upper crust. The thickness distribution of the crust is also discussed with respect to the tectonic framework. Furthermore, gravity as well as magnetic modelling points to an intrusive complex beneath the Central Graben within the Entenschnabel area. On the other hand, this work provides a geological-geophysical consistent 3D gravity and magnetic model that can be used as a starting point for further investigation of this part of the German North Sea.

Atmospheric Profiles, Clouds and the Evolution of Sea Ice Cover in the Beaufort and Chukchi Seas: Atmospheric Observations and Modeling as Part of the Seasonal Ice Zone Reconnaissance Surveys

Science.gov (United States)

2017-06-04

further, changes in lower atmospheric temperature, humidity, winds , and clouds are likely to result from changed sea ice concentrations and ocean...affect changes in cloud properties and cover, • develop novel instrumentation including low cost, expendable, air-deployed micro -aircraft to obtain...from June through October to obtain atmospheric profiles of temperature, humidity, and winds from the time of ice edge retreat in spring to advance

Western Ross Sea continental slope gravity currents

Science.gov (United States)

Gordon, Arnold L.; Orsi, Alejandro H.; Muench, Robin; Huber, Bruce A.; Zambianchi, Enrico; Visbeck, Martin

2009-06-01

Antarctic Bottom Water of the world ocean is derived from dense Shelf Water that is carried downslope by gravity currents at specific sites along the Antarctic margins. Data gathered by the AnSlope and CLIMA programs reveal the presence of energetic gravity currents that are formed over the western continental slope of the Ross Sea when High Salinity Shelf Water exits the shelf through Drygalski Trough. Joides Trough, immediately to the east, offers an additional escape route for less saline Shelf Water, while the Glomar Challenger Trough still farther east is a major pathway for export of the once supercooled low-salinity Ice Shelf Water that forms under the Ross Ice Shelf. The Drygalski Trough gravity currents increase in thickness from ˜100 to ˜400 m on proceeding downslope from ˜600 m (the shelf break) to 1200 m (upper slope) sea floor depth, while turning sharply to the west in response to the Coriolis force during their descent. The mean current pathway trends ˜35° downslope from isobaths. Benthic-layer current and thickness are correlated with the bottom water salinity, which exerts the primary control over the benthic-layer density. A 1-year time series of bottom-water current and hydrographic properties obtained on the slope near the 1000 m isobath indicates episodic pulses of Shelf Water export through Drygalski Trough. These cold (34.75) pulses correlate with strong downslope bottom flow. Extreme examples occurred during austral summer/fall 2003, comprising concentrated High Salinity Shelf Water (-1.9 °C; 34.79) and approaching 1.5 m s -1 at descent angles as large as ˜60° relative to the isobaths. Such events were most common during November-May, consistent with a northward shift in position of the dense Shelf Water during austral summer. The coldest, saltiest bottom water was measured from mid-April to mid-May 2003. The summer/fall export of High Salinity Shelf Water observed in 2004 was less than that seen in 2003. This difference, if real

Individual animals and other data collected using visual observations and other instruments from AIRCRAFT in the Bering Sea and other seas from 02 September 1990 to 07 November 1991 (NODC Accession 9200080)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Individual Animal and other data were collected using visual observation and other instruments from AIRCRAFT in the Bering Sea, Chukchi Sea, and Arctic Ocean. Data...

High-resolution sub-bottom seismic and sediment core records from the Chukchi Abyssal Plain reveal Quaternary glaciation impacts on the western Arctic Ocean

Science.gov (United States)

Joe, Y. J.; Seokhoon, Y.; Nam, S. I.; Polyak, L.; Niessen, F.

2017-12-01

For regional context of the Quaternary history of Arctic marine glaciations, such as glacial events in northern North America and on the Siberian and Chukchi margins, we used CHIRP sub-bottom profiles (SBP) along with sediment cores, including a 14-m long piston core ARA06-04JPC taken from the Chukchi abyssal plain during the RV Araon expedition in 2015. Based on core correlation with earlier developed Arctic Ocean stratigraphies using distribution of various sedimentary proxies, core 04JPC is estimated to extend to at least Marine Isotope Stage 13 (>0.5 Ma). The stratigraphy developed for SBP lines from the Chukchi abyssal plain to surrounding slopes can be divided into four major seismostratigraphic units (SSU 1-4). SBP records from the abyssal plain show well preserved stratification, whereas on the surrounding slopes this pattern is disrupted by lens-shaped, acoustically transparent sedimentary bodies interpreted as glaciogenic debris flow deposits. Based on the integration of sediment physical property and SBP data, we conclude that these debris flows were generated during several ice-sheet grounding events on the Chukchi and East Siberian margins, including adjacent ridges and plateaus, during the middle to late Quaternary.

Mercury biomagnification in food webs of the northeastern Chukchi Sea, Alaskan Arctic

Science.gov (United States)

Fox, Austin L.; Trefry, John H.; Trocine, Robert P.; Dunton, Kenneth H.; Lasorsa, Brenda K.; Konar, Brenda; Ashjian, Carin J.; Cooper, Lee W.

2017-10-01

Predictive tools and a large new dataset for the northeastern Chukchi Sea (NECS) are used here to help identify regional differences and potential future shifts in the magnitude of Hg biomagnification in the Arctic. At the base of the food web in the NECS, concentrations of total mercury (THg) in phytoplankton (20-μm mesh) ranged from 4-42 ng g-1 dry weight, partly in response to variations in algal biomass and water temperature. A >3-fold increase in monomethylmercury (MMHg) was observed in zooplankton (4.3±0.7 ng g-1) relative to phytoplankton (150-fold and from 85%, respectively, from phytoplankton to muscle in the whelk Plicifusus kroeyeri (279 ng g-1, TL 4.5). For muscle tissue in 10 species plus whole phytoplankton and zooplankton, the trophic magnification slope (TMS) for MMHg (log10[MMHg]=m(δ15N)+b; where m=TMS) was 0.23±0.02 (SE). No significant differences in TMS were found for the NECS plus three other studies from the eastern Canadian Arctic (average TMS=0.24±0.02). Nevertheless, all data for MMHg in biota from the NECS plotted below the combined best fit line for all four studies. Results from an ANCOVA showed that statistically different (p=0.001) intercept values (b), not TMS, best explained the >2-fold lower concentrations of MMHg in biota from the NECS (b=-1.85) relative to the same species from the eastern Canadian Arctic (b=-1.29). Future changes that affect bioaccumulation of MMHg in the Arctic may impact the biomagnification equation by shifting the TMS, intercept or both. The intercept is more likely to respond to changes in productivity and concentrations of dissolved Hg whereas the TMS may respond to changing growth rates due to fluctuations in productivity and food availability. In either case, small changes in the intercept or TMS coincide with predictably large increases or decreases in MMHg concentrations in apex predators.

Temporal sea-surface gravity changes observed near the source area prior to the 2011 Tohoku earthquake

Science.gov (United States)

Nakamura, T.; Tsuboi, S.

2013-12-01

Recent seismological studies suggested subsurface activities preceding the 2011 Tohoku earthquake; the occurrence of migration of seismicity (Kato et al., 2012) and slow slip events (Ito et al., 2013) in and around the source area one month before the mainshock. In this study, we investigated sea-surface gravity changes observed by the shipboard gravimeter mounted on research vessels before the mainshock. The vessels incidentally passed through the source area along almost the same cruise track twice, four months before and one month before the mainshock. Comparing the sea surface gravity in the former track with that in the latter after Bouguer correction, we find the gravity changes of approximately 7 mGal in coseismic slip areas near the trench axis during the three months. We find these gravity changes even in the crossing areas of the cruise tracks where seafloor topographies have no differences between the tracks. We also find that the topographic differences show positive changes but the gravity changes negative ones in other areas, which is a negative correlation inconsistent with the theoretical relationship between the topographic difference and the gravity change. These mean that the differences of seafloor topographies due to differences between the two cruise tracks are not main causes of the observed gravity changes there. The changes cannot also be explained by drifts of the gravimeter and geostrophic currents. Although we have not had any clear evidences, we speculate that the possible cause may be density increases around the seismogenic zone or uplifts of seafloor in order to explain the changes of this size. We estimate the density increases of 1.0 g/cm**3 in a disk with a radius of 40 km and a width of 200 m or the uplifts of several tens of meters in seafloor areas for the observed gravity changes. Our results indicate that sea-surface gravity observations may be one of valid approaches to monitor the approximate location of a possible great

Analysis of selected gravity profiles on the Hanford Reservation, Richland, Washington

International Nuclear Information System (INIS)

Little, J.T.; Richard, B.H.

1977-07-01

Regional gravity surveys have been conducted on the Hanford Reservation in the past. This analysis is an attempt at detailed gravity profiling over selected areas of the reservation. Over 450 gravity readings were taken during the summer of 1976. The Bouguer anomaly values of these stations, along with facies cross sections, were used to construct two-dimensional models. The models depict the buried basalt bedrock surface and the overlying sedimentary cover of the areas selected for profiling. In the eastern section of the reservation, the interpretation of the data suggests that there are three major buried valleys cut into the bedrock. These channels are most likely a combination of structural downwarping and erosion of these downwarps by an ancestral Columbia River. Along the western boundary of the reservation there are two closed depressions which are believed to be the result of the sub-fluvial vortex effect of Kolk erosion. It was found that, although two-dimensional gravity models are useful in determining the buried bedrock surface, they are ineffectual in delineating sedimentary contacts

Dynamics of flexural gravity waves: from sea ice to Hawking radiation and analogue gravity.

Science.gov (United States)

Das, S; Sahoo, T; Meylan, M H

2018-01-01

The propagation of flexural gravity waves, routinely used to model wave interaction with sea ice, is studied, including the effect of compression and current. A number of significant and surprising properties are shown to exist. The occurrence of blocking above a critical value of compression is illustrated. This is analogous to propagation of surface gravity waves in the presence of opposing current and light wave propagation in the curved space-time near a black hole, therefore providing a novel system for studying analogue gravity. Between the blocking and buckling limit of the compressive force, the dispersion relation possesses three positive real roots, contrary to an earlier observation of having a single positive real root. Negative energy waves, in which the phase and group velocity point in opposite directions, are also shown to exist. In the presence of an opposing current and certain critical ranges of compressive force, the second blocking point shifts from the positive to the negative branch of the dispersion relation. Such a shift is known as the Hawking effect from the analogous behaviour in the theory of relativity which leads to Hawking radiation. The theory we develop is illustrated with simulations of linear waves in the time domain.

Aircraft Surveys of the Beaufort Sea Seasonal Ice Zone

Science.gov (United States)

Morison, J.

2016-02-01

The Seasonal Ice Zone Reconnaissance Surveys (SIZRS) is a program of repeated ocean, ice, and atmospheric measurements across the Beaufort-Chukchi sea seasonal sea ice zone (SIZ) utilizing US Coast Guard Arctic Domain Awareness (ADA) flights of opportunity. The SIZ is the region between maximum winter sea ice extent and minimum summer sea ice extent. As such, it contains the full range of positions of the marginal ice zone (MIZ) where sea ice interacts with open water. The increasing size and changing air-ice-ocean properties of the SIZ are central to recent reductions in Arctic sea ice extent. The changes in the interplay among the atmosphere, ice, and ocean require a systematic SIZ observational effort of coordinated atmosphere, ice, and ocean observations covering up to interannual time-scales, Therefore, every year beginning in late Spring and continuing to early Fall, SIZRS makes monthly flights across the Beaufort Sea SIZ aboard Coast Guard C-130H aircraft from USCG Air Station Kodiak dropping Aircraft eXpendable CTDs (AXCTD) and Aircraft eXpendable Current Profilers (AXCP) for profiles of ocean temperature, salinity and shear, dropsondes for atmospheric temperature, humidity, and velocity profiles, and buoys for atmosphere and upper ocean time series. Enroute measurements include IR imaging, radiometer and lidar measurements of the sea surface and cloud tops. SIZRS also cooperates with the International Arctic Buoy Program for buoy deployments and with the NOAA Earth System Research Laboratory atmospheric chemistry sampling program on board the aircraft. Since 2012, SIZRS has found that even as SIZ extent, ice character, and atmospheric forcing varies year-to-year, the pattern of ocean freshening and radiative warming south of the ice edge is consistent. The experimental approach, observations and extensions to other projects will be discussed.

Long-term and seasonal Caspian Sea level change from satellite gravity and altimeter measurements

Science.gov (United States)

Chen, J. L.; Wilson, C. R.; Tapley, B. D.; Save, H.; Cretaux, Jean-Francois

2017-03-01

We examine recent Caspian Sea level change by using both satellite radar altimetry and satellite gravity data. The altimetry record for 2002-2015 shows a declining level at a rate that is approximately 20 times greater than the rate of global sea level rise. Seasonal fluctuations are also much larger than in the world oceans. With a clearly defined geographic region and dominant signal magnitude, variations in the sea level and associated mass changes provide an excellent way to compare various approaches for processing satellite gravity data. An altimeter time series derived from several successive satellite missions is compared with mass measurements inferred from Gravity Recovery and Climate Experiment (GRACE) data in the form of both spherical harmonic (SH) and mass concentration (mascon) solutions. After correcting for spatial leakage in GRACE SH estimates by constrained forward modeling and accounting for steric and terrestrial water processes, GRACE and altimeter observations are in complete agreement at seasonal and longer time scales, including linear trends. This demonstrates that removal of spatial leakage error in GRACE SH estimates is both possible and critical to improving their accuracy and spatial resolution. Excellent agreement between GRACE and altimeter estimates also provides confirmation of steric Caspian Sea level change estimates. GRACE mascon estimates (both the Jet Propulsion Laboratory (JPL) coastline resolution improvement version 2 solution and the Center for Space Research (CSR) regularized) are also affected by leakage error. After leakage corrections, both JPL and CSR mascon solutions also agree well with altimeter observations. However, accurate quantification of leakage bias in GRACE mascon solutions is a more challenging problem.

Sea level rise in the Arctic Ocean

OpenAIRE

Proshutinsky, Andrey; Pavlov, Vladimir; Bourke, Robert H.

2001-01-01

The article of record as published may be found at http://dx.doi.org/10.1029/2000GL012760 About 60 tide-gauge stations in the Kara, Laptev, East-Siberian and Chukchi Seas have recorded the sea level change from the 1950s through 1990s. Over this 40-year period, most of these stations show a significant sea level rise (SLR). In light of global change, this SLR could be a manifestation of warming in the Artic coupled with a decrease of sea ice extent, warming of Atlantic waters, changes in...

Ocean Profile Measurements During the Seasonal Ice Zone Reconnaissance Surveys

Science.gov (United States)

2014-09-30

ice cover in 2014. The consequent reduced melting early in the summer delays the onset of sea - ice - albedo feed back in accelerating melt throughout the...Chukchi sea seasonal sea ice zone (SIZ) utilizing US Coast Guard Arctic Domain Awareness (ADA) flights of opportunity. This report covers our grant...region between maximum winter sea ice extent and minimum summer sea ice extent. As such, it contains the full range of positions of the marginal ice

The 3.6 ka Aniakchak tephra in the Arctic Ocean: a constraint on the Holocene radiocarbon reservoir age in the Chukchi Sea

Science.gov (United States)

Pearce, Christof; Varhelyi, Aron; Wastegård, Stefan; Muschitiello, Francesco; Barrientos, Natalia; O'Regan, Matt; Cronin, Thomas M.; Gemery, Laura; Semiletov, Igor; Backman, Jan; Jakobsson, Martin

2017-04-01

The caldera-forming eruption of the Aniakchak volcano in the Aleutian Range on the Alaskan Peninsula at 3.6 cal kyr BP was one of the largest Holocene eruptions worldwide. The resulting ash is found as a visible sediment layer in several Alaskan sites and as a cryptotephra on Newfoundland and Greenland. This large geographic distribution, combined with the fact that the eruption is relatively well constrained in time using radiocarbon dating of lake sediments and annual layer counts in ice cores, makes it an excellent stratigraphic marker for dating and correlating mid-late Holocene sediment and paleoclimate records. This study presents the outcome of a targeted search for the Aniakchak tephra in a marine sediment core from the Arctic Ocean, namely Core SWERUS-L2-2-PC1 (2PC), raised from 57 m water depth in Herald Canyon, western Chukchi Sea. High concentrations of tephra shards, with a geochemical signature matching that of Aniakchak ash, were observed across a more than 1.5 m long sediment sequence. Since the primary input of volcanic ash is through atmospheric transport, and assuming that bioturbation can account for mixing up to ca. 10 cm of the marine sediment deposited at the coring site, the broad signal is interpreted as sustained reworking at the sediment source input. The isochron is therefore placed at the base of the sudden increase in tephra concentrations rather than at the maximum concentration. This interpretation of major reworking is strengthened by analysis of grain size distribution which points to ice rafting as an important secondary transport mechanism of volcanic ash. Combined with radiocarbon dates on mollusks in the same sediment core, the volcanic marker is used to calculate a marine radiocarbon reservoir age offset ΔR = 477 ± 60 years. This relatively high value may be explained by the major influence of typically carbon-old Pacific waters, and it agrees well with recent estimates of ΔR along the northwest Alaskan coast, possibly

Seasonal Ice Zone Reconnaissance Surveys Coordination and Ocean Profiles

Science.gov (United States)

2015-09-30

measurements across the Beaufort- Chukchi sea seasonal sea ice zone (SIZ) utilizing US Coast Guard Arctic Domain Awareness ( ADA ) flights of opportunity...such, it contains the full range of positions of the marginal ice zone (MIZ) where sea ice interacts with open water. In addition to SIZRS...This grant coordinates the various SIZRS observations on the ADA flights, assures integration with modeling efforts, serves as the SIZRS point of

A Quantitative Proxy for Sea-Ice Based on Diatoms: A Cautionary Tale.

Science.gov (United States)

Nesterovich, A.; Caissie, B.

2016-12-01

Sea ice in the Polar Regions supports unique and productive ecosystems, but the current decline in the Arctic sea ice extent prompts questions about previous sea ice declines and the response of ice related ecosystems. Since satellite data only extend back to 1978, the study of sea ice before this time requires a proxy. Being one of the most productive, diatom-dominated regions in the world and having a wide range of sea ice concentrations, the Bering and Chukchi seas are a perfect place to find a relationship between the presence of sea ice and diatom community composition. The aim of this work is to develop a diatom-based proxy for the sea ice extent. A total of 473 species have been identified in 104 sediment samples, most of which were collected on board the US Coast Guard Cutter Healy ice breaker (2006, 2007) and the Norseman II (2008). The study also included some of the archived diatom smear slides made from sediments collected in 1969. The assemblages were compared to satellite-derived sea ice extent data averaged over the 10 years preceding the sampling. Previous studies in the Arctic and Antarctic regions demonstrated that the Generalized Additive Model (GAM) is one of the best choices for proxy construction. It has the advantage of using only several species instead of the whole assemblage, thus including only sea ice-associated species and minimizing the noise created by species responding to other environmental factors. Our GAM on three species (Connia compita, Fragilariopsis reginae-jahniae, and Neodenticula seminae) has low standard deviation, high level of explained variation, and holds under the ten-fold cross-validation; the standard residual analysis is acceptable. However, a spatial residual analysis revealed that the model consistently over predicts in the Chukchi Sea and under predicts in the Bering Sea. Including a spatial model into the GAM didn't improve the situation. This has led us to test other methods, including a non-parametric model

Sea bottom gravity survey of Osaka bay and its study; Osakawan kaitei juryoku chosa to sono kosatsu

Energy Technology Data Exchange (ETDEWEB)

Komazawa, M [Geological Survey of Japan, Tsukuba (Japan); Ota, Y; Shibuya, S; Kumai, M; Murakami, M [Japex Geoscience Institute, Inc., Tokyo (Japan)

1996-05-01

This paper reports a sea bottom gravity survey conducted with an objective to identify deep underground structure in the vicinity of the epicenter of the Hyogoken-Nanbu Earthquake. The surveyed areas are the whole Osaka Bay area north of the north latitude of 34 degrees and 20 minutes, and the eastern part of the Sea of Harima east of the east longitude of 134 degrees and 40 minutes, excluding the areas difficult of performing measurements. A square lattice with sides each about 2 km was arranged with 408 measurement points. The measurement was carried out by using an observation vessel mounted with a sea bottom gravimeter made by LaCoste and Romberg Corporation, which was lowered down to the sea bottom at the measurement points. Errors in positions and water depths at the gravity measuring points were suppressed to less than 0.002 minutes and 0.1 m, respectively. The measurement data were given necessary corrections by using a unified method applicable also to land areas, and a Bouguer anomaly chart was prepared. Based on the chart, this paper summarizes features in the Bouguer anomaly in the surveyed areas (such as the low-gravity anomaly band extending the central part of the Osaka bay from north-east to south-west, and the gradient structure existing on the Awaji island side). 6 refs., 1 fig.

Interpretation of recent gravity profiles over the ophiolite belt, Northern Oman Mountains, United Arab Emirates

Science.gov (United States)

Khattab, M. M.

1993-04-01

The compiled Bouguer gravity anomaly map over parts of the ophiolite rocks of the Northern Oman Mountains suggests the existence of three partially serpentinized nappes: two along the Gulf of Oman coast with axes near Dadnah, near Fujira and the third 17 km SSE of Masafi. Modeling of the subsurface geology, beneath two gravity profiles (Diba-Kalba and Masafi-Fujira), is based on the occurrence (field evidence) of multiphase low-angle thrusting of the members of the Tethyan lithosphere in northern and Oman Mountains. An assumed crustal model at the Arabian continental margin, beneath the Masafi-Fujira profile, is made to explain an intense gravity gradient. Gravity interpretation is not inconsistent with a gliding mechanism for obduction of the ophiolite on this part of the Arabian continental margin.

Trophodynamics of the Hanna Shoal Ecosystem (Chukchi Sea, Alaska): Connecting multiple end-members to a rich food web

Science.gov (United States)

McTigue, N. D.; Dunton, K. H.

2017-10-01

Predicting how alterations in sea ice-mediated primary production will impact Arctic food webs remains a challenge in forecasting ecological responses to climate change. One top-down approach to this challenge is to elucidate trophic roles of consumers as either specialists (i.e., consumers of predominantly one food resource) or generalists (i.e., consumers of multiple food resources) to categorize the dependence of consumers on each primary producer. At Hanna Shoal in the Chukchi Sea, Alaska, we used stable carbon and nitrogen isotope data to quantify trophic redundancy with standard ellipse areas at both the species and trophic guild levels. We also investigated species-level trophic plasticity by analyzing the varying extents that three end-members were assimilated by the food web using the mixing model simmr (Stable Isotope Mixing Model in R). Our results showed that ice algae, a combined phytoplankton and sediment organic matter composite (PSOM), and a hypothesized microphytobenthos (MPB) component were incorporated by consumers in the benthic food web, but their importance varied by species. Some primary consumers relied heavily on PSOM (e.g, the amphipods Ampelisca sp. and Byblis sp.; the copepod Calanus sp.), while others exhibited generalist feeding and obtained nutrition from multiple sources (e.g., the holothuroidean Ocnus glacialis, the gastropod Tachyrhynchus sp., the sipunculid Golfingia margaritacea, and the bivalves Ennucula tenuis, Nuculana pernula, Macoma sp., and Yoldia hyperborea). Most higher trophic level benthic predators, including the gastropods Buccinum sp., Cryptonatica affinis, and Neptunea sp, the seastar Leptasterias groenlandica, and the amphipod Anonyx sp. also exhibited trophic plasticity by coupling energy pathways from multiple primary producers including PSOM, ice algae, and MPB. Our stable isotope data indicate that consumers in the Hanna Shoal food web exhibit considerable trophic redundancy, while few species were specialists

Expansion of the South China Sea basin: Constraints from magnetic anomaly stripes, sea floor topography, satellite gravity and submarine geothermics

Directory of Open Access Journals (Sweden)

Xuezhong Yu

2017-01-01

Full Text Available The widely distributed E–W-trending magnetic anomaly stripes in the central basin and the N–E-trending magnetic anomaly stripes in the southwest sub-basin provide the most important evidence for Neogene expansion of the South China Sea. The expansion mechanism remains, however, controversial because of the lack of direct drilling data, non-systematic marine magnetic survey data, and irregular magnetic anomaly stripes with two obvious directions. For example, researchers have inferred different ages and episodes of expansion for the central basin and southwest sub-basin. Major controversy centers on the order of basinal expansion and the mechanism of expansion for the entire South China Sea basin. This study attempts to constrain these problems from a comprehensive analysis of the seafloor topography, magnetic anomaly stripes, regional aeromagnetic data, satellite gravity, and submarine geothermics. The mapped seafloor terrain shows that the central basin is a north-south rectangle that is relatively shallow with many seamounts, whereas the southwest sub-basin is wide in northeast, gradually narrows to the southwest, and is relatively deeper with fewer seamounts. Many magnetic anomaly stripes are present in the central basin with variable dimensions and directions that are dominantly EW-trending, followed by the NE-, NW- and NS-trending. Conversely such stripes are few in the southwest sub-basin and mainly NE-trending. Regional magnetic data suggest that the NW-trending Ailaoshan-Red River fault extends into the South China Sea, links with the central fault zone in the South China Sea, which extends further southward to Reed Tablemount. Satellite gravity data show that both the central basin and southwest sub-basin are composed of oceanic crust. The Changlong seamount is particularly visible in the southwest sub-basin and extends eastward to the Zhenbei seamount. Also a low gravity anomaly zone coincides with the central fault zone in the sub

Alkane and polycyclic aromatic hydrocarbons in sediments and benthic invertebrates of the northern Chukchi Sea

Science.gov (United States)

Harvey, H. Rodger; Taylor, Karen A.

2017-10-01

The Hanna Shoal region represents an important northern gateway for transport and deposition in the Chukchi Sea. This study determined the concentration and distribution of organic contaminants (aliphatic hydrocarbon and polycyclic aromatic hydrocarbons, PAHs) in surface sediments from 34 sites across Hanna Shoal. Up to 31 total PAHs, including parent and alkyl homologues were detected with total concentrations ranging from a low of 168 ng g-1 the western flank of Hanna Shoal (station H34) to 1147 ng g-1 at station in Barrow Canyon (station BarC5). Alkyl PAHs were more abundant than parent structures and accounted for 53-64% of the summed concentrations suggesting overall at background levels (< 1600 ng g-1) in sediments. Alkane (C15-C33) hydrocarbons ranged from 4.3 μg g-1 on the southern flank of Hanna shoal to 31 μg g-1 at a northern station. Sediments were often dominated by short chain (C15-C22) alkanes with overall terrestrial aquatic ratios (TAR) for the region averaging 0.20. Based on the ratio of Fl/(Fl+ Py) and BaF/(Baf+BeP) verses (BA/BA+Ch) in sediments, PAHs are largely derived from petrogenic sources with minor amounts of mixed combustion sources. A diversity of PAHs were detected in the northern whelk Neptunea heros foot muscle with total concentrations ranging from 0.14 to 1.5 μg g-1 dry tissue wt. Larger (and presumably older) animals showed higher levels of PAH per unit muscle tissue, suggesting that animals may bioaccumulate PAHs over time, with low but increasing concentrations also present in internal and external eggs. Alkane hydrocarbons were also higher in whelks with distributions similar to that seen in sediments. The mussel Muscularus discors collected in Barrow Canyon showed constrained distributions and substantially lower concentrations of both PAHs and alkanes than the surrounding surface sediments.

Time Series of Transport and Currents on the Chukchi Shelf: 2010 - 2015

Science.gov (United States)

Stabeno, P. J.; Ladd, C. A.; Mordy, C. W.; Sullivan, M. E.

2016-02-01

Starting in 2010, NOAA/EcoFOCI in partnership with BOEM, has measured currents and water properties at multiple mooring sites on the Chukchi shelf and slope. Observations began at three sites (C1, C2, C3) off Icy Cape in 2010 and expanded in 2013 to include three sites around Barrow Canyon and two sites northeast of Hanna Shoal. In 2014, a mooring was deployed on the slope (1000 m) northeast of Hanna Shoal. A near-continuous velocity record exists at C2 from August 2010 - September 2015. These velocity data are combined with 40 satellite-tracked drifter trajectories (drogue depth 30 m) and hydrographic transects (2010 - 2015) to examine flow patterns and transport on the eastern Chukchi shelf. Six primary hydrographic transects extending from Pt. Hope (DBO3) to Barrow Canyon (DBO5) were occupied most years. Transport past Icy Cape accounts for 40% of the transport through Bering Strait. Maximum monthly-mean transport (>0.8 Sv) is in July with low interannual variability, while the lowest monthly transports are in December - April with high interannual variability. Currents are significantly correlated with alongshore winds. Satellite-tracked drifters deployed near Bering Strait show onshelf flow at Central Channel. Drifters deployed along the Icy Cape line are transported northeastward, converging to a narrow flow, and mainly exit the shelf through Barrow Canyon. The drifters then travel westward along the slope. In summer, drifters and hydrographic sections delineate the pathways of the nutrient-poor Alaska Coastal Current, and the nutrient-rich water to the west (Bering Sea water and Anadyr water). These data were collected mainly as part of three BOEM funded projects (CHAOZ, CHAOZ-Extension and ArcWEST).

Recent Changes in Arctic Sea Ice Melt Onset, Freeze-Up, and Melt Season Length

Science.gov (United States)

Markus, Thorsten; Stroeve, Julienne C.; Miller, Jeffrey

2010-01-01

In order to explore changes and trends in the timing of Arctic sea ice melt onset and freeze-up and therefore melt season length, we developed a method that obtains this information directly from satellite passive microwave data, creating a consistent data set from 1979 through present. We furthermore distinguish between early melt (the first day of the year when melt is detected) and the first day of continuous melt. A similar distinction is made for the freeze-up. Using this method we analyze trends in melt onset and freeze-up for 10 different Arctic regions. In all regions except for the Sea of Okhotsk, which shows a very slight and statistically insignificant positive trend (O.4 days/decade), trends in melt onset are negative, i.e. towards earlier melt. The trends range from -1.0day/decade for the Bering Sea to -7.3 days/decade for the East Greenland Sea. Except for the Sea of Okhotsk all areas also show a trend towards later autumn freeze onset. The Chukchi/Beaufort Seas and Laptev/East Siberian Seas observe the strongest trends with 7 days/decade. For the entire Arctic, the melt season length has increased by about 20 days over the last 30 years. Largest trends of over 1O days/decade are seen for Hudson Bay, the East Greenland Sea the Laptev/East Siberian Seas, and the Chukchi/Beaufort Seas. Those trends are statistically significant a1 the 99% level.

Current measurements collected at three moorings deployed across the Chukchi continental slope west of the Chukchi Rise in the Chukchi Borderland region to measure the Arctic Ocean boundary current, 2002-08 to 2002-09 (NODC Accession 0002693)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A 35-day NSF-sponsored cruise aboard the USCGC Polar Star has studied in depth the physical oceanography of the Chukchi Borderland and Mendeleev Ridge regions. An...

Gene transcription in polar bears (Ursus maritimus) from disparate populations

Science.gov (United States)

Bowen, Lizabeth; Miles, A. Keith; Waters, Shannon C.; Meyerson, Randi; Rode, Karyn D.; Atwood, Todd C.

2015-01-01

Polar bears in the Beaufort (SB) and Chukchi (CS) Seas experience different environments due primarily to a longer history of sea ice loss in the Beaufort Sea. Ecological differences have been identified as a possible reason for the generally poorer body condition and reproduction of Beaufort polar bears compared to those from the Chukchi, but the influence of exposure to other stressors remains unknown. We use molecular technology, quantitative PCR, to identify gene transcription differences among polar bears from the Beaufort and Chukchi Seas as well as captive healthy polar bears. We identified significant transcriptional differences among a priori groups (i.e., captive bears, SB 2012, SB 2013, CS 2013) for ten of the 14 genes of interest (i.e., CaM, HSP70, CCR3, TGFβ, COX2, THRα, T-bet, Gata3, CD69, and IL17); transcription levels of DRβ, IL1β, AHR, and Mx1 did not differ among groups. Multivariate analysis also demonstrated separation among the groups of polar bears. Specifically, we detected transcript profiles consistent with immune function impairment in polar bears from the Beaufort Sea, when compared with Chukchi and captive polar bears. Although there is no strong indication of differential exposure to contaminants or pathogens between CS and SB bears, there are clearly differences in important transcriptional responses between populations. Further investigation is warranted to refine interpretation of potential effects of described stress-related conditions for the SB population.

Particle creation phenomenology, Dirac sea and the induced Weyl and Einstein-dilaton gravity

Energy Technology Data Exchange (ETDEWEB)

Berezin, V.A.; Dokuchaev, V.I.; Eroshenko, Yu.N., E-mail: berezin@inr.ac.ru, E-mail: dokuchaev@inr.ac.ru, E-mail: eroshenko@inr.ac.ru [Institute for Nuclear Research, Russian Academy of Sciences, 60th October Anniversary Prospect 7a, 117312 Moscow (Russian Federation)

2017-01-01

We constructed the conformally invariant model for scalar particle creation induced by strong gravitational fields. Starting from the 'usual' hydrodynamical description of the particle motion written in the Eulerian coordinates we substituted the particle number conservation law (which enters the formalism) by 'the particle creation law', proportional to the square of the Weyl tensor (following the famous result by Ya.B. Zel'dovich and A.A. Starobinsky). Then, demanding the conformal invariance of the whole dynamical system, we have got both the (Weyl)-conformal gravity and the Einstein-Hilbert gravity action integral with dilaton field. Thus, we obtained something like the induced gravity suggested first by A.D. Sakharov. It is shown that the resulting system is self-consistent. We considered also the vacuum equations. It is shown that, beside the 'empty vacuum', there may exist the 'dynamical vacuum', which is nothing more but the Dirac sea. The latter is described by the unexpectedly elegant equation which includes both the Bach and Einstein tensors and the cosmological terms.

Geochemistry of obsidian from Krasnoe Lake on the Chukchi Peninsula (Northeastern Siberia)

Science.gov (United States)

Popov, V. K.; Grebennikov, A. V.; Kuzmin, Ya. V.; Glascock, M. D.; Nozdrachev, E. A.; Budnitsky, S. Yu.; Vorobey, I. E.

2017-09-01

This report considers features of the geochemical composition of obsidian from beach sediments of Krasnoe Lake along the lower course of the Anadyr River, as well as from lava-pyroclastic rocks constituting the lake coastal outcrops and the surrounding branches of Rarytkin Ridge. The two geochemical types of obsidian, for the first time distinguished and researched, correspond in their chemical composition to lavas and ignimbrite-like tuffs of rhyolites from the Rarytkin area. The distinguished types represent the final stage of acidic volcanism in the West Kamchatkan-Koryak volcanic belt. It was assumed that the accumulation of obsidian in coastal pebble beds was caused by the erosion of extrusive domes and pyroclastic flows. The geochemical studies of obsidian artifacts from archeological sites of the regions of the Sea of Okhotsk, the Kolyma River, and the Chukchi Peninsula along with the correlation of geological and archeological samples show that Krasnoe Lake was an important source of "archeological" obsidian in Northeastern Siberia.

Exploring the utility of quantitative network design in evaluating Arctic sea ice thickness sampling strategies

OpenAIRE

Kaminski, T.; Kauker, F.; Eicken, H.; Karcher, M.

2015-01-01

We present a quantitative network design (QND) study of the Arctic sea ice-ocean system using a software tool that can evaluate hypothetical observational networks in a variational data assimilation system. For a demonstration, we evaluate two idealised flight transects derived from NASA's Operation IceBridge airborne ice surveys in terms of their potential to improve ten-day to five-month sea-ice forecasts. As target regions for the forecasts we select the Chukchi Sea, a...

Comparison of TL profiles in recent sea cores

Energy Technology Data Exchange (ETDEWEB)

Castagnoli, G C; Bonino, G

1985-01-01

The thermoluminescence (TL) profile of different recent Tyrrhenian sea cores sampled at various intervals during the last centuries have been compared in order to check the reproducibility of the profiles and investigate the possibility of using the results for monitoring solar-terrestrial relations in the past. The satisfactory results obtained by comparison of two different cores in the time interval 1755-1969 A.D. has demonstrated: (a) the two TL profiles are correlated; (b) the 11 yr cycle corresponding to the main solar cycle is evident in both TL profiles.

Tectonic evolution of the Qumran Basin from high-resolution 3.5-kHz seismic profiles and its implication for the evolution of the northern Dead Sea Basin

Science.gov (United States)

Lubberts, Ronald K.; Ben-Avraham, Zvi

2002-02-01

The Dead Sea Basin is a morphotectonic depression along the Dead Sea Transform. Its structure can be described as a deep rhomb-graben (pull-apart) flanked by two block-faulted marginal zones. We have studied the recent tectonic structure of the northwestern margin of the Dead Sea Basin in the area where the northern strike-slip master fault enters the basin and approaches the western marginal zone (Western Boundary Fault). For this purpose, we have analyzed 3.5-kHz seismic reflection profiles obtained from the northwestern corner of the Dead Sea. The seismic profiles give insight into the recent tectonic deformation of the northwestern margin of the Dead Sea Basin. A series of 11 seismic profiles are presented and described. Although several deformation features can be explained in terms of gravity tectonics, it is suggested that the occurrence of strike-slip in this part of the Dead Sea Basin is most likely. Seismic sections reveal a narrow zone of intensely deformed strata. This zone gradually merges into a zone marked by a newly discovered tectonic depression, the Qumran Basin. It is speculated that both structural zones originate from strike-slip along right-bending faults that splay-off from the Jordan Fault, the strike-slip master fault that delimits the active Dead Sea rhomb-graben on the west. Fault interaction between the strike-slip master fault and the normal faults bounding the transform valley seems the most plausible explanation for the origin of the right-bending splays. We suggest that the observed southward widening of the Dead Sea Basin possibly results from the successive formation of secondary right-bending splays to the north, as the active depocenter of the Dead Sea Basin migrates northward with time.

Analysis of gravity anomalies in the Ulleung Basin (East Sea/Sea of Japan) and its implications for the crustal structure of rift-dominated back-arc basin

Science.gov (United States)

Kim, Yoon-Mi; Lee, Sang-Mook

2018-01-01

The Ulleung Basin (UB), one of three major basins in the East Sea/Sea of Japan, is considered to represent a continental-rifting end-member of back-arc basin system, but is much less understood compared to the nearby Yamato Basin (YB) and Japan Basin (JB). This study examines the gravity anomalies of the UB since the variation in crustal thickness can provide important insights on the mode of extension during basin opening. Our analysis shows that the Moho depth (from the sea surface) varies from 16 km at the basin center to 22 km at the edges. However, within the central part of the basin, the crustal thickness (not including sediment) is more or less the same (10-12 km), by varying only about 10-20% of the total thickness, contrary to the previous suggestions. Our finding of anomalous but uniformly thick crust is consistent with the recent seismic results from the YB (14 km on average). A mantle residual gravity anomaly high (∼20 mGal) exists in the northeastern part of the UB. This feature is interpreted as the location of maximum extension (slightly thinner crust by ∼1 km). Together with another moderate gravity high to the southwest, the two anomalies form a NNE-SSW line, which corresponds to the direction of the major tectonic structures of the Korean Peninsula. We argue that the a massive magmatic emplacement took place extensively in the lower crust of the UB during the opening, significantly increasing its overall thickness to almost twice as that of the JB where a mid-ocean-ridge style seafloor spreading occurred. Two important post-opening processes took place after the formation of uniformly thick crust: post-rift volcanic intrusions in the north, especially in its northeast sections but had little effect on the residual gravity anomaly itself, and the deflection of crust in response to differential sediment loading towards the south, producing the median high in the basement in response to the flexural bending. We also conducted a simple test to

Metabolite Profiling of Red Sea Corals

KAUST Repository

Ortega, Jovhana Alejandra

2016-12-01

Looking at the metabolite profile of an organism provides insights into the metabolomic state of a cell and hence also into pathways employed. Little is known about the metabolites produced by corals and their algal symbionts. In particular, corals from the central Red Sea are understudied, but interesting study objects, as they live in one of the warmest and most saline environments and can provide clues as to the adjustment of corals to environmental change. In this study, we applied gas chromatography – mass spectrometry (GC–MS) metabolite profiling to analyze the metabolic profile of four coral species and their associated symbionts: Fungia granulosa, Acropora hemprichii, Porites lutea, and Pocillopora verrucosa. We identified and quantified 102 compounds among primary and secondary metabolites across all samples. F. granulosa and its symbiont showed a total of 59 metabolites which were similar to the 51 displayed by P. verrucosa. P. lutea and A. hemprichii both harbored 40 compounds in conjunction with their respective isolated algae. Comparing across species, 28 metabolites were exclusively present in algae, while 38 were exclusive to corals. A principal component and cluster analyses revealed that metabolite profiles clustered between corals and algae, but each species harbored a distinct catalog of metabolites. The major classes of compounds were carbohydrates and amino acids. Taken together, this study provides a first description of metabolites of Red Sea corals and their associated symbionts. As expected, the metabolites of coral hosts differ from their algal symbionts, but each host and algal species harbor a unique set of metabolites. This corroborates that host-symbiont species pairs display a fine-tuned complementary metabolism that provide insights into the specific nature of the symbiosis. Our analysis also revealed aquatic pollutants, which suggests that metabolite profiling might be used for monitoring pollution levels and assessing

Effect of longitudinal profile on the seismic anaysis of concrete gravity dams

International Nuclear Information System (INIS)

El-Nady, A.; Ghobarah, A.; Aziz, T.S.

1992-01-01

The traditional three-dimensional analysis of concrete gravity dams is expensive and very difficult. An alternate approach is to divide the dam into substructures. Each monolith is considered as a substructure and its degrees of freedom are reduced to those on the contact surfaces with the adjacent monoliths as well as a few Ritz vectors. Using this procedure high accuracy was achieved using a reasonable number of degrees of freedom. The analysis is carried out in the frequency domain to account for the frequency dependent parameters in the reservoir substructure. The procedure was tested and compared to typical three-dimensional analysis and was found to give high accuracy. A simplified cross section of gravity dams with different longitudinal profiles was studied using the substructuring procedure as well as a typical two-dimensional analysis. The results obtained show a significant variation in dynamic properties of the dam from that calculated assuming two-dimensional analysis. Furthermore, the response of the dam varies significantly when including the effect of longitudinal profile of the structure. It is concluded that the two-dimensional representation of the structure may substantially overestimate the response of the dam, depending on its longitudinal profile, especially when keyed joints are used in the construction. 13 refs., 5 figs., 4 tabs

Constraining Saturn's interior density profile from precision gravity field measurement obtained during Grand Finale

Science.gov (United States)

Movshovitz, N.; Fortney, J. J.; Helled, R.; Hubbard, W. B.; Mankovich, C.; Thorngren, D.; Wahl, S. M.; Militzer, B.; Durante, D.

2017-12-01

The external gravity field of a planetary body is determined by the distribution of mass in its interior. Therefore, a measurement of the external field, properlyinterpreted, tells us about the interior density profile, ρ(r), which in turn can be used to constrain the composition in the interior and thereby learn about theformation mechanism of the planet. Recently, very high precision measurements of the gravity coefficients for Saturn have been made by the radio science instrument on the Cassini spacecraft during its Grand Finale orbits. The resulting coefficients come with an associated uncertainty. The task of matching a given density profile to a given set of gravity coefficients is relatively straightforward, but the question of how to best account for the uncertainty is not. In essentially all prior work on matching models to gravity field data inferences about planetary structure have rested on assumptions regarding the imperfectly known H/He equation of state and the assumption of an adiabatic interior. Here we wish to vastly expand the phase space of such calculations. We present a framework for describing all the possible interior density structures of a Jovian planet constrained by a given set of gravity coefficients and their associated uncertainties. Our approach is statistical. We produce a random sample of ρ(a) curves drawn from the underlying (and unknown) probability distribution of all curves, where ρ is the density on an interior level surface with equatorial radius a. Since the resulting set of density curves is a random sample, that is, curves appear with frequency proportional to the likelihood of their being consistent with the measured gravity, we can compute probability distributions for any quantity that is a function of ρ, such as central pressure, oblateness, core mass and radius, etc. Our approach is also Bayesian, in that it can utilize any prior assumptions about the planet's interior, as necessary, without being overly

Temperature and other data were collected using thermometer and bottle casts in the Chukchi and Bering Sea from 1947-02-11 to 1949-07-26 (NODC Accession 9700081)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature, depth, oxygen, and salinity data were collected using thermometer and bottle casts from the USS CACOPAN, USS NEREUS, and HMCS CEDARWOOD in the Chukchi...

The earth's shape and gravity

CERN Document Server

Garland, G D; Wilson, J T

2013-01-01

The Earth's Shape and Gravity focuses on the progress of the use of geophysical methods in investigating the interior of the earth and its shape. The publication first offers information on gravity, geophysics, geodesy, and geology and gravity measurements. Discussions focus on gravity measurements and reductions, potential and equipotential surfaces, absolute and relative measurements, and gravity networks. The text then elaborates on the shape of the sea-level surface and reduction of gravity observations. The text takes a look at gravity anomalies and structures in the earth's crust; interp

Optical properties of melting first-year Arctic sea ice

Science.gov (United States)

Light, Bonnie; Perovich, Donald K.; Webster, Melinda A.; Polashenski, Christopher; Dadic, Ruzica

2015-11-01

The albedo and transmittance of melting, first-year Arctic sea ice were measured during two cruises of the Impacts of Climate on the Eco-Systems and Chemistry of the Arctic Pacific Environment (ICESCAPE) project during the summers of 2010 and 2011. Spectral measurements were made for both bare and ponded ice types at a total of 19 ice stations in the Chukchi and Beaufort Seas. These data, along with irradiance profiles taken within boreholes, laboratory measurements of the optical properties of core samples, ice physical property observations, and radiative transfer model simulations are employed to describe representative optical properties for melting first-year Arctic sea ice. Ponded ice was found to transmit roughly 4.4 times more total energy into the ocean, relative to nearby bare ice. The ubiquitous surface-scattering layer and drained layer present on bare, melting sea ice are responsible for its relatively high albedo and relatively low transmittance. Light transmittance through ponded ice depends on the physical thickness of the ice and the magnitude of the scattering coefficient in the ice interior. Bare ice reflects nearly three-quarters of the incident sunlight, enhancing its resiliency to absorption by solar insolation. In contrast, ponded ice absorbs or transmits to the ocean more than three-quarters of the incident sunlight. Characterization of the heat balance of a summertime ice cover is largely dictated by its pond coverage, and light transmittance through ponded ice shows strong contrast between first-year and multiyear Arctic ice covers.

Sea Ice Evolution in the Pacific Arctic by Selected CMIP5 Models: the Present and the Future

Science.gov (United States)

Wang, M.; Yang, Q.; Overland, J. E.; Stabeno, P. J.

2016-12-01

With fast declining of sea ice cover in the Arctic, the timing of sea ice break-up and freeze-up is an urgent economic, social and scientific issue. Based on daily sea ice concentration data we assess three parameters: the dates of sea ice break-up and freeze-up and the annual sea ice duration in the Pacific Arctic. The sea ice duration is shrinking, with the largest trend during the past decade (1990-2015); this declining trend will continue based on CMIP5 model projections. The seven CMIP5 models used in current study are able to simulate all three parameters well when compared with observations. Comparisons made at eight Chukchi Sea mooring sites and the eight Distributed Biological Observatory (DBO) boxes show consistent results as well. The 30-year averaged trend for annual sea ice duration is projected to be -0.68 days/year to -1.2 days/year for 2015-2044. This is equivalent 20 to 36 days reduction in the annual sea ice duration. A similar magnitude of the negative trend is also found at all eight DBO boxes. The reduction in annual sea ice duration will include both earlier break-up dates and later freeze-up date. However, models project that a later freeze-up contributes more than early break-up to the overall shortening of annual sea ice duration. Around the Bering Strait future changes are the smallest, with less than 20-days change in duration during next 30 years. Upto 60 days reduction of the sea ice duration is projected for the decade of 2030-2044 in the East Siberia, the Chukchi and the Beaufort Seas.

Marine Geoid Undulation Assessment Over South China Sea Using Global Geopotential Models and Airborne Gravity Data

Science.gov (United States)

Yazid, N. M.; Din, A. H. M.; Omar, K. M.; Som, Z. A. M.; Omar, A. H.; Yahaya, N. A. Z.; Tugi, A.

2016-09-01

Global geopotential models (GGMs) are vital in computing global geoid undulations heights. Based on the ellipsoidal height by Global Navigation Satellite System (GNSS) observations, the accurate orthometric height can be calculated by adding precise and accurate geoid undulations model information. However, GGMs also provide data from the satellite gravity missions such as GRACE, GOCE and CHAMP. Thus, this will assist to enhance the global geoid undulations data. A statistical assessment has been made between geoid undulations derived from 4 GGMs and the airborne gravity data provided by Department of Survey and Mapping Malaysia (DSMM). The goal of this study is the selection of the best possible GGM that best matches statistically with the geoid undulations of airborne gravity data under the Marine Geodetic Infrastructures in Malaysian Waters (MAGIC) Project over marine areas in Sabah. The correlation coefficients and the RMS value for the geoid undulations of GGM and airborne gravity data were computed. The correlation coefficients between EGM 2008 and airborne gravity data is 1 while RMS value is 0.1499.In this study, the RMS value of EGM 2008 is the lowest among the others. Regarding to the statistical analysis, it clearly represents that EGM 2008 is the best fit for marine geoid undulations throughout South China Sea.

Deglacial remobilization of permafrost carbon to sediments along the East Siberian Arctic Seas

Science.gov (United States)

Martens, J.; Wild, B.; Bröder, L.; Andersson, A.; Pearce, C.; O'Regan, M.; Jakobsson, M.; Tesi, T.; Muschitiello, F.; Sköld, M.; Semiletov, I. P.; Dudarev, O.; Gustafsson, O.

2017-12-01

Current climate change is expected to thaw large quantities of permafrost carbon (PF-C) and expose it to degradation which emits greenhouse gases (i.e. CO2 and CH4). Warming causes a gradual deepening of the seasonally thawed active layer surface of permafrost soils, but also the abrupt collapse of deeper Ice Complex Deposits (ICD), especially along Siberian coastlines. It was recently hypothesized that past warming already induced large-scale permafrost degradation after the last glacial, which ultimately amplified climate forcing. We here assess the mobilization of PF-C to East Siberian Arctic Sea sediments during these warming periods. We perform source apportionment using bulk carbon isotopes (ΔΔ14C, δ13C) together with terrestrial biomarkers (CuO-derived lignin phenols) as indicators for PF-C transfer. We apply these techniques to sediment cores (SWERUS-L2) from the Chukchi Sea (4-PC1) and the southern Lomonosov Ridge (31-PC1). We found that PF-C fluxes during the Bølling-Allerød warming (14.7 to 12.7 cal ka BP), the Younger Dryas cooling (12.7 to 11.7 cal ka BP) and the early Holocene warming (until 11 cal ka BP) were overall higher than mid and late Holocene fluxes. In the Chukchi Sea, PF-C burial was 2x higher during the deglaciation (7.2 g m-2 a-1) than in the mid and late Holocene (3.6 g m-2 a-1), and ICD were the dominant source of PF-C (79.1%). Smaller fractions originated from the active layer (9.1%) and marine sources (11.7%). We conclude that thermo-erosion of ICD released large amounts of PF-C to the Chukchi Sea, likely driven by climate warming and the deglacial sea level rise. This contrasts to earlier analyses of Laptev Sea sediments where active layer material from river transport dominated the carbon flux. Preliminary data on lignin phenol concentrations of Lomonosov Ridge sediments suggest that the postglacial remobilization of PF-C was one order of magnitude higher (10x) than during both the preceding glacial and the subsequent Holocene

Characterizing Arctic Sea Ice Topography Using High-Resolution IceBridge Data

Science.gov (United States)

Petty, Alek; Tsamados, Michel; Kurtz, Nathan; Farrell, Sinead; Newman, Thomas; Harbeck, Jeremy; Feltham, Daniel; Richter-Menge, Jackie

2016-01-01

We present an analysis of Arctic sea ice topography using high resolution, three-dimensional, surface elevation data from the Airborne Topographic Mapper, flown as part of NASA's Operation IceBridge mission. Surface features in the sea ice cover are detected using a newly developed surface feature picking algorithm. We derive information regarding the height, volume and geometry of surface features from 2009-2014 within the Beaufort/Chukchi and Central Arctic regions. The results are delineated by ice type to estimate the topographic variability across first-year and multi-year ice regimes.

Wave Climate and Wave Mixing in the Marginal Ice Zones of Arctic Seas, Observations and Modelling

Science.gov (United States)

2015-09-30

measured by R/V Lance ( black solid line) and predicted by SWAN ( black dashed line) and the ship velocity (grey solid line). (c) BFI ( black solid line) and...and potential future trends; and WAVEWATCH-III® and SWAN wave models with new physics, adapted and validated for the Beaufort and Chukchi Seas...nondimensional spectral width ν ( black dashed line). (d–i) Selected photographs from the ship show local sea ice state. Fig. 6 illustrates a

Gravity-Driven Deposits in an Active Margin (Ionian Sea) Over the Last 330,000 Years

Science.gov (United States)

Köng, Eléonore; Zaragosi, Sébastien; Schneider, Jean-Luc; Garlan, Thierry; Bachèlery, Patrick; Sabine, Marjolaine; San Pedro, Laurine

2017-11-01

In the Ionian Sea, the subduction of the Nubia plate underneath the Eurasia plate leads to an important sediment remobilization on the Calabrian Arc and the Mediterranean Ridge. These events are often associated with earthquakes and tsunamis. In this study, we analyze gravity-driven deposits in order to establish their recurrence time on the Calabrian Arc and the western Mediterranean Ridge. Four gravity cores collected on ridges and slope basins of accretionary prisms record turbidites, megaturbidites, slumping and micro-faults over the last 330,000 years. These turbidites were dated by correlation with a hemipelagic core with a multi-proxy approach: radiometric dating, δ18O, b* colour curve, sapropels and tephrochronology. The origin of the gravity-driven deposits was studied with a sedimentary approach: grain-size, lithology, thin section, geochemistry of volcanic glass. The results suggest three periods of presence/absence of gravity-driven deposits: a first on the western lobe of the Calabrian Arc between 330,000 and 250,000 years, a second between 120,000 years and present day on the eastern lobe of the Calabrian Arc and over the last 60,000 years on the western lobe, and a third on the Mediterranean Ridge over the last 37,000 years. Return times for gravity-driven deposits are around 1,000 years during the most important record periods. The turbidite activity also highlights the presence of volcaniclastic turbidites that seems to be link to the Etna changing morphology over the last 320,000 years.

Impact of combining GRACE and GOCE gravity data on ocean circulation estimates

Directory of Open Access Journals (Sweden)

T. Janjić

2012-02-01

Full Text Available With the focus on the Southern Ocean circulation, results of assimilation of multi-mission-altimeter data and the GRACE/GOCE gravity data into the finite element ocean model (FEOM are investigated. We use the geodetic method to obtain the dynamical ocean topography (DOT. This method combines the multi-mission-altimeter sea surface height and the GRACE/GOCE gravity field. Using the profile approach, the spectral consistency of both fields is achieved by filtering the sea surface height and the geoid. By combining the GRACE and GOCE data, a considerably shorter filter length can be used, which results in more DOT details. We show that this increase in resolution of measured DOT carries onto the results of data assimilation for the surface data. By assimilating only absolute dynamical topography data using the ensemble Kalman filter, we were able to improve modeled fields. Results are closer to observations which were not used for assimilation and lie outside the area covered by altimetry in the Southern Ocean (e.g. temperature of surface drifters or deep temperatures in the Weddell Sea area at 800 m depth derived from Argo composite.

Constraining the interior density profile of a Jovian planet from precision gravity field data

Science.gov (United States)

Movshovitz, Naor; Fortney, Jonathan J.; Helled, Ravit; Hubbard, William B.; Thorngren, Daniel; Mankovich, Chris; Wahl, Sean; Militzer, Burkhard; Durante, Daniele

2017-10-01

The external gravity field of a planetary body is determined by the distribution of mass in its interior. Therefore, a measurement of the external field, properly interpreted, tells us about the interior density profile, ρ(r), which in turn can be used to constrain the composition in the interior and thereby learn about the formation mechanism of the planet. Planetary gravity fields are usually described by the coefficients in an expansion of the gravitational potential. Recently, high precision measurements of these coefficients for Jupiter and Saturn have been made by the radio science instruments on the Juno and Cassini spacecraft, respectively.The resulting coefficients come with an associated uncertainty. And while the task of matching a given density profile with a given set of gravity coefficients is relatively straightforward, the question of how best to account for the uncertainty is not. In essentially all prior work on matching models to gravity field data, inferences about planetary structure have rested on imperfect knowledge of the H/He equation of state and on the assumption of an adiabatic interior. Here we wish to vastly expand the phase space of such calculations. We present a framework for describing all the possible interior density structures of a Jovian planet, constrained only by a given set of gravity coefficients and their associated uncertainties. Our approach is statistical. We produce a random sample of ρ(a) curves drawn from the underlying (and unknown) probability distribution of all curves, where ρ is the density on an interior level surface with equatorial radius a. Since the resulting set of density curves is a random sample, that is, curves appear with frequency proportional to the likelihood of their being consistent with the measured gravity, we can compute probability distributions for any quantity that is a function of ρ, such as central pressure, oblateness, core mass and radius, etc. Our approach is also bayesian, in that

A Multiscale Nested Modeling Framework to Simulate the Interaction of Surface Gravity Waves with Nonlinear Internal Gravity Waves

Science.gov (United States)

2015-09-30

Interaction of Surface Gravity Waves with Nonlinear Internal Gravity Waves Lian Shen St. Anthony Falls Laboratory and Department of Mechanical...on studying surface gravity wave evolution and spectrum in the presence of surface currents caused by strongly nonlinear internal solitary waves...interaction of surface and internal gravity waves in the South China Sea. We will seek answers to the following questions: 1) How does the wind-wave

Iceberg and meltwater discharge events in the western Arctic Ocean since MIS 5: a comparison of sediment cores off the East Siberian and Chukchi margins

Science.gov (United States)

Xiao, W.; Wang, R.; Zhang, T.; Duan, X.; Polyak, L.

2017-12-01

In the Pleistocene the western Arctic Ocean was affected by deglacial discharge events from ice sheets in northern North America as well as the East Siberian and Chukchi margins. Distribution of Ice Rafted Debris (IRD) >250 μm and planktonic foraminiferal N. pachyderma (sin.) (Nps) δ18O and δ13C was compared in CHINARE sediment cores ARC2-M03 (Wang et al., 2013) and ARC3-P37 from the Chukchi Abyssal Plain and Northwind Ridge, respectively, to identify the impacts of icebergs and meltwater on paleoceanographic environments since MIS 5. The IRD is mainly composed of quartz grains and fragments of clastic rocks and detrital carbonates. The carbonates, mostly dolomites characteristic of the Canadian Arctic Archipelago (CAA) provenance, typically anti-correlate with quartz and clastic rocks, indicating different sources such as Chukchi-Alaskan or East Siberian margin. Most of the Nps δ18O depletions correspond to peaks in detrital carbonates, suggesting a strong influence of meltwater from the Laurentide Ice Sheet (LIS) on the western Arctic Ocean. A conspicuous dark gray interval interpreted to represent glacial/deglacial environments of MIS 4/3 age, shows a remarkable depletion in Nps δ13C along with high δ18O values and absence of IRD. This unusual signature may be related to a persistent sea-ice cover and/or high fluxes of terrigenous material with deglacial debris flows. In a younger grey interval corresponding to MIS2, high abundances of quartz and clastic rocks in the Northwind Ridge core ARC3-P37 indicate iceberg discharge from areas other than CAA, such as the Mackenzie LIS lobe or Chukchi-Alaskan margin. The MIS2-Holocene transition is marked by an increase in detrital carbonates co-occurring with Nps δ13C and δ18O depletion (Polyak et al., 2007), indicative of LIS iceberg/meltwater fluxes from the CAA. We note that stable-isotope events in the study area may go unnoticed because of gaps in foraminiferal records related to dissolution and/or adverse

Seasonal variability of the Red Sea, from GRACE time-variable gravity and altimeter sea surface height measurements

Science.gov (United States)

Wahr, John; Smeed, David; Leuliette, Eric; Swenson, Sean

2014-05-01

Seasonal variability of sea surface height and mass within the Red Sea, occurs mostly through the exchange of heat with the atmosphere and wind-driven inflow and outflow of water through the strait of Bab el Mandab that opens into the Gulf of Aden to the south. The seasonal effects of precipitation and evaporation, of water exchange through the Suez Canal to the north, and of runoff from the adjacent land, are all small. The flow through the Bab el Mandab involves a net mass transfer into the Red Sea during the winter and a net transfer out during the summer. But that flow has a multi-layer pattern, so that in the summer there is actually an influx of cool water at intermediate (~100 m) depths. Thus, summer water in the southern Red Sea is warmer near the surface due to higher air temperatures, but cooler at intermediate depths (especially in the far south). Summer water in the northern Red Sea experiences warming by air-sea exchange only. The temperature profile affects the water density, which impacts the sea surface height but has no effect on vertically integrated mass. Here, we study this seasonal cycle by combining GRACE time-variable mass estimates, altimeter (Jason-1, Jason-2, and Envisat) measurements of sea surface height, and steric sea surface height contributions derived from depth-dependent, climatological values of temperature and salinity obtained from the World Ocean Atlas. We find good consistency, particularly in the northern Red Sea, between these three data types. Among the general characteristics of our results are: (1) the mass contributions to seasonal SSHT variations are much larger than the steric contributions; (2) the mass signal is largest in winter, consistent with winds pushing water into the Red Sea through the Strait of Bab el Mandab in winter, and out during the summer; and (3) the steric signal is largest in summer, consistent with summer sea surface warming.

Change in coccolith morphology by responding to temperature and salinity in coccolithophore Emiliania huxleyi (Haptophyta) isolated from the Bering and Chukchi Seas

Science.gov (United States)

Saruwatari, K.; Satoh, M.; Harada, N.; Suzuki, I.; Shiraiwa, Y.

2015-11-01

Strains of the coccolithophore Emiliania huxleyi (Haptophyta) collected from the subarctic North Pacific and Arctic Oceans during the R/V MIRAI cruise in 2010 (MR10-05) were established as clone cultures and have been maintained in the laboratory at 15 °C and 32 ‰ salinity. To study the physiological responses of coccolith formation to changes in temperature and salinity, growth experiments and morphometric investigations were performed on two strains of MR57N isolated from the northern Bering Sea (56°58' N, 167°11' W) and MR70N at the Chukchi Sea (69°99' N, 168° W). This is the first report of a detailed morphometric and morphological investigation of Arctic Ocean coccolithophore strains. The specific growth rates at the logarithmic growth phases in both strains markedly increased as temperature was elevated from 5 to 20 °C, although coccolith productivity (the percentage of calcified cells) was similar at 10-20 % at all temperatures. On the other hand, the specific growth rate of strain MR70N was affected less by changes in salinity in the range 26-35 ‰, but the proportion of calcified cells decreased at high and low salinities. According to scanning electron microscopy (SEM) observations, coccolith morphotypes can be categorized into Type B/C on the basis of their biometrical parameters, such as length of the distal shield (LDS), length of the inner central area (LICA), and the thickness of distal shield elements. The central area elements of coccoliths varied from grilled type to closed type when temperature was increased or salinity was decreased, and coccolith size decreased simultaneously. Coccolithophore cell size also decreased with increasing temperature, although the variation in cell size was slightly greater at the lower salinity level. This indicates that subarctic and arctic coccolithophore strains can survive in a wide range of seawater temperatures and at lower salinities due to their marked morphometric adaptation ability. Because all

Two and Three Parameter Waveform Retracking of Cryosat-2 LRM Waveforms for Gravity Field Determination

DEFF Research Database (Denmark)

Jain, Maulik; Andersen, Ole Baltazar; Dall, Jørgen

2013-01-01

The project deals with sea surface height and gravity field determination in open ocean using Cryosat-2 LRM data. A three parameter model is being used to find the retracking offset for sea surface height determination. The estimates from the three parameter model are further improved upon by using...... a two parameter model. The sea surface heights thus obtained are used to develop sea surface height anomalies which are further processed to give gravity fields. Retracker performance evaluation is done using sea surface height anomaly and gravity field anomaly....

Critical Mechanisms for the Formation of Extreme Arctic Sea-Ice Extent in the Summers of 2007 and 1996

Energy Technology Data Exchange (ETDEWEB)

Dong, Xiquan [Beijing Normal Univ. (China); Univ. of North Dakota, Grand Forks, ND (United States); Zib, Benjamin J. [Univ. of North Dakota, Grand Forks, ND (United States); Xi, Baike [Univ. of North Dakota, Grand Forks, ND (United States); Stanfield, Ryan [Univ. of North Dakota, Grand Forks, ND (United States); Deng, Yi [Georgia Inst. of Technology, Atlanta, GA (United States); Zhang, Xiangdong [Univ. of Alaska, Fairbanks, AK (United States); Lin, B. [NASA Langley Research Center, Hampton, VA (United States); Long, Charles N. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2013-08-29

A warming Arctic climate is undergoing significant e 21 nvironmental change, most evidenced by the reduction of Arctic sea-ice extent during the summer. In this study, we examine two extreme anomalies of September sea-ice extent in 2007 and 1996, and investigate the impacts of cloud fraction (CF), atmospheric precipitable water vapor (PWV), downwelling longwave flux (DLF), surface air temperature (SAT), pressure and winds on the sea-ice variation in 2007 and 1996 using both satellite-derived sea-ice products and MERRA reanalysis. The area of the Laptev, East Siberian and West Chukchi seas (70-90oN, 90-180oE) has experienced the largest variation in sea-ice extent from year-to-year and defined here as the Area Of Focus (AOF). The record low September sea-ice extent in 2007 was associated with positive anomalies 30 of CF, PWV, DLF, and SAT over the AOF. Persistent anti-cyclone positioned over the Beaufort Sea coupled with low pressure over Eurasia induced easterly zonal and southerly meridional winds. In contrast, negative CF, PWV, DLF and SAT anomalies, as well as opposite wind patterns to those in 2007, characterized the 1996 high September sea-ice extent. Through this study, we hypothesize the following positive feedbacks of clouds, water vapor, radiation and atmospheric variables on the sea-ice retreat during the summer 2007. The record low sea-ice extent during the summer 2007 is initially triggered by the atmospheric circulation anomaly. The southerly winds across the Chukchi and East Siberian seas transport warm, moist air from the north Pacific, which is not only enhancing sea-ice melt across the AOF, but also increasing clouds. The positive cloud feedback results in higher SAT and more sea-ice melt. Therefore, 40 more water vapor could be evaporated from open seas and higher SAT to form more clouds, which will enhance positive cloud feedback. This enhanced positive cloud feedback will then further increase SAT and accelerate the sea-ice retreat during the

Study of Under-ice Blooms In the Chukchi Ecosystem (SUBICE) (HLY1401, EM122)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The primary objectives of SUBICE were to determine the spatial distribution of large under-ice phytoplankton blooms on the Chukchi Shelf and the physical mechanisms...

Change in coccolith size and morphology due to response to temperature and salinity in coccolithophore Emiliania huxleyi (Haptophyta) isolated from the Bering and Chukchi seas

Science.gov (United States)

Saruwatari, Kazuko; Satoh, Manami; Harada, Naomi; Suzuki, Iwane; Shiraiwa, Yoshihiro

2016-05-01

Strains of the coccolithophore Emiliania huxleyi (Haptophyta) collected from the subarctic North Pacific and Arctic oceans in 2010 were established as clone cultures and have been maintained in the laboratory at 15 °C and 32 ‰ salinity. To study the physiological responses of coccolith formation to changes in temperature and salinity, growth experiments and morphometric investigations were performed on two strains, namely MR57N isolated from the northern Bering Sea and MR70N at the Chukchi Sea. This is the first report of a detailed morphometric and morphological investigation of Arctic Ocean coccolithophore strains. The specific growth rates at the logarithmic growth phases in both strains markedly increased as temperature was elevated from 5 to 20 °C, although coccolith productivity (estimated as the percentage of calcified cells) was similar at 10-20 % at all temperatures. On the other hand, the specific growth rate of MR70N was affected less by changes in salinity in the range 26-35 ‰, but the proportion of calcified cells decreased at high and low salinities. According to scanning electron microscopy (SEM) observations, coccolith morphotypes can be categorized into Type B/C on the basis of their biometrical parameters. The central area elements of coccoliths varied from thin lath type to well-calcified lath type when temperature was increased or salinity was decreased, and coccolith size decreased simultaneously. Coccolithophore cell size also decreased with increasing temperature, although the variation in cell size was slightly greater at the lower salinity level. This indicates that subarctic and arctic coccolithophore strains can survive in a wide range of seawater temperatures and at lower salinities with change in their morphology. Because all coccolith biometric parameters followed the scaling law, the decrease in coccolith size was caused simply by the reduced calcification. Taken together, our results suggest that calcification productivity may

Anatomy of a late spring snowfall on sea ice

Science.gov (United States)

Perovich, Donald; Polashenski, Christopher; Arntsen, Alexandra; Stwertka, Carolyn

2017-03-01

Spring melt initiation is a critical process for Arctic sea ice. Melting conditions decrease surface albedo at a time of high insolation, triggering powerful albedo feedback. Weather events during melt initiation, such as new snowfalls, can stop or reverse the albedo decline, however. Here we present field observations of such a snow event and demonstrate its enduring impact through summer. Snow fell 3-6 June 2014 in the Chukchi Sea, halting melt onset. The snow not only raised albedo but also provided a significant negative latent heat flux, averaging -51 W m-2 from 3 to 6 June. The snowfall delayed sustained melt by 11 days, creating cascading impacts on surface energy balance that totaled some 135 MJ/m2 by mid-August. The findings highlight the sensitivity of sea ice conditions on seasonal time scales to melt initiation processes.

Sea surface temperature as a proxy for convective gravity wave excitation: a study based on global gravity wave observations in the middle atmosphere

Directory of Open Access Journals (Sweden)

J. Y. Jia

2014-11-01

Full Text Available Absolute values of gravity wave momentum flux (GWMF deduced from satellite measurements by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER instrument and the High Resolution Dynamics Limb Sounder (HIRDLS are correlated with sea surface temperature (SST with the aim of identifying those oceanic regions for which convection is a major source of gravity waves (GWs. Our study identifies those latitude bands where high correlation coefficients indicate convective excitation with confidence. This is based on a global ray-tracing simulation, which is used to delineate the source and wind-filtering effects. Convective GWs are identified at the eastern coasts of the continents and over the warm water regions formed by the warm ocean currents, in particular the Gulf Stream and the Kuroshio. Potential contributions of tropical cyclones to the excitation of the GWs are discussed. Convective excitation can be identified well into the mid-mesosphere. In propagating upward, the centers of GWMF formed by convection shift poleward. Some indications of the main forcing regions are even shown for the upper mesosphere/lower thermosphere (MLT.

Seasonal Ice Zone Reconnaissance Surveys Coordination

Science.gov (United States)

2016-03-30

Chukchi sea seasonal sea ice zone (SIZ) utilizing US Coast Guard Arctic Domain Awareness ( ADA ) flights of opportunity in the summers of 2012- 2014. In...measurements across the Beaufort-Chukchi sea seasonal sea ice zone (SIZ) utilizing US Coast Guard Arctic Domain Awareness ( ADA ) flights of...such, it contains the full range of positions of the marginal ice zone (MIZ) where sea ice interacts with open water. In addition to SIZRS

Space use of a dominant Arctic vertebrate: Effects of prey, sea ice, and land on Pacific walrus resource selection

Science.gov (United States)

Beatty, William; Jay, Chadwick V.; Fischbach, Anthony S.; Grebmeier, Jacqueline M.; Taylor, Rebecca L.; Blanchard, Arny L.; Jewett, Stephen C.

2016-01-01

Sea ice dominates marine ecosystems in the Arctic, and recent reductions in sea ice may alter food webs throughout the region. Sea ice loss may also stress Pacific walruses (Odobenus rosmarus divergens), which feed on benthic macroinvertebrates in the Bering and Chukchi seas. However, no studies have examined the effects of sea ice on foraging Pacific walrus space use patterns. We tested a series of hypotheses that examined walrus foraging resource selection as a function of proximity to resting substrates and prey biomass. We quantified walrus prey biomass with 17 benthic invertebrate families, which included bivalves, polychaetes, amphipods, tunicates, and sipunculids. We included covariates for distance to sea ice and distance to land, and systematically developed a series of candidate models to examine interactions among benthic prey biomass and resting substrates. We ranked candidate models with Bayesian Information Criterion and made inferences on walrus resource selection based on the top-ranked model. Based on the top model, biomass of the bivalve family Tellinidae, distance to ice, distance to land, and the interaction of distances to ice and land all positively influenced walrus foraging resource selection. Standardized model coefficients indicated that distance to ice explained the most variation in walrus foraging resource selection followed by Tellinidae biomass. Distance to land and the interaction of distances to ice and land accounted for similar levels of variation. Tellinidae biomass likely represented an index of overall bivalve biomass, indicating walruses focused foraging in areas with elevated levels of bivalve and tellinid biomass. Our results also emphasize the importance of sea ice to walruses. Projected sea ice loss will increase the duration of the open water season in the Chukchi Sea, altering the spatial distribution of resting sites relative to current foraging areas and possibly affecting the spatial structure of benthic communities.

Charnock's Roughness Length Model and Non-dimensional Wind Profiles Over the Sea

DEFF Research Database (Denmark)

Pena Diaz, Alfredo; Gryning, Sven-Erik

2008-01-01

An analysis tool for the study of wind speed profiles over the water has been developed. The profiles are analysed using a modified dimensionless wind speed and dimensionless height, assuming that the sea surface roughness can be predicted by Charnock's roughness length model. In this form, the r...

Processing Marine Gravity Data Around Korea

Science.gov (United States)

Lee, Y.; Choi, K.; Kim, Y.; Ahn, Y.; Chang, M.

2008-12-01

In Korea currently 4 research ships are under operating in Korea, after the first research vessel equipped shipborne gravity meter was introduced in 1990s. These are Onnuri(launch 1991) of KORDI(Korea Ocean Research & Development Institute), Haeyang2000(launch 1996), Badaro1(launch 2002) of NORI(National Oceanographic Research Institute) and Tamhae2(launch 1997) of KIGAM(Korea Institute of Geoscience and Mineral Resources). Those of research vessel, Haeyang2000 have observed marine gravity data over 150,000 points each year from year 1996 to year 2003. Haeyang2000, about 2,500 tons, is unable to operate onshore so NORI has constructed another 600 tons research ship Badaro1 that has observed marine gravity data onshore since year 2002. Haeyang2000 finished observing marine gravity data offshore within Korean territorial waters until year 2003. Currently Badaro1 is observing marine gravity data onshore. These shipborne gravity data will be very useful and important on geodesy and geophysics research also those data can make a contribution to developing these studies. In this study NORI's shipbrne gravity data from 1996 to 2007 has been processed for fundamental data to compute Korean precise geoid. Marine gravity processing steps as followed. 1. Check the time sequence, latitude and longitude position, etc. of shipborne gravity data 2. Arrangement of the tide level below the pier and meter drift correction of each cruise. 3. Elimination of turning points. 4. The time lag correction. 5. Computation of RV's velocities, Heading angles and the Eötvös correction. 6. Kalman filtering of GPS navigation data using cross-over points. 7. Cross-over correction using least square adjustment. About 2,058,000 points have been processed with NORI's marine gravity data from 1996 to 2007 in this study. The distribution of free-air anomalies was -41.0 mgal to 136.0 mgal(mean 8.90mgal) within Korean territorial waters. The free-air anomalies processed with the marine gravity data are

Can we constrain postglacial sedimentation in the western Arctic Ocean by ramped pyrolysis 14C? A case study from the Chukchi-Alaskan margin.

Science.gov (United States)

Suzuki, K.; Yamamoto, M.; Rosenheim, B. E.; Omori, T.; Polyak, L.; Nam, S. I.

2017-12-01

The Arctic Ocean underwent dramatic climate changes in the past. Variations in sea-ice extent and ocean current system in the Arctic cause changes in surface albedo and deep water formation, which have global climatic implications. However, Arctic paleoceanographic studies are lagging behind the other oceans due largely to chronostratigraphic difficulties. One of the reasons for this is a scant presence of material suitable for 14C dating in large areas of the Arctic seafloor. To enable improved age constraints for sediments impoverished in datable material, we apply ramped pyrolysis 14C method (Ramped PyrOx 14C, Rosenheim et al., 2008) to sedimentary records from the Chukchi-Alaska margin recovering Holocene to late-glacial deposits. Samples were divided into five fraction products by gradual heating sedimentary organic carbon from ambient laboratory temperature to 1000°C. The thermographs show a trimodal pattern of organic matter decomposition over temperature, and we consider that CO2 generated at the lowest temperature range was derived from autochthonous organic carbon contemporaneous with sediment deposition, similar to studies in the Antarctic margin and elsewhere. For verification of results, some of the samples treated for ramped pyrolysis 14C were taken from intervals dated earlier by AMS 14C using bivalve mollusks. Ultimately, our results allow a new appraisal of deglacial to Holocene deposition at the Chukchi-Alaska margin with potential to be applied to other regions of the Arctic Ocean.

Impact of Arctic sea-ice retreat on the recent change in cloud-base height during autumn

Science.gov (United States)

Sato, K.; Inoue, J.; Kodama, Y.; Overland, J. E.

2012-12-01

Cloud-base observations over the ice-free Chukchi and Beaufort Seas in autumn were conducted using a shipboard ceilometer and radiosondes during the 1999-2010 cruises of the Japanese R/V Mirai. To understand the recent change in cloud base height over the Arctic Ocean, these cloud-base height data were compared with the observation data under ice-covered situation during SHEBA (the Surface Heat Budget of the Arctic Ocean project in 1998). Our ice-free results showed a 30 % decrease (increase) in the frequency of low clouds with a ceiling below (above) 500 m. Temperature profiles revealed that the boundary layer was well developed over the ice-free ocean in the 2000s, whereas a stable layer dominated during the ice-covered period in 1998. The change in surface boundary conditions likely resulted in the difference in cloud-base height, although it had little impact on air temperatures in the mid- and upper troposphere. Data from the 2010 R/V Mirai cruise were investigated in detail in terms of air-sea temperature difference. This suggests that stratus cloud over the sea ice has been replaced as stratocumulus clouds with low cloud fraction due to the decrease in static stability induced by the sea-ice retreat. The relationship between cloud-base height and air-sea temperature difference (SST-Ts) was analyzed in detail using special section data during 2010 cruise data. Stratus clouds near the sea surface were predominant under a warm advection situation, whereas stratocumulus clouds with a cloud-free layer were significant under a cold advection situation. The threshold temperature difference between sea surface and air temperatures for distinguishing the dominant cloud types was 3 K. Anomalous upward turbulent heat fluxes associated with the sea-ice retreat have likely contributed to warming of the lower troposphere. Frequency distribution of the cloud-base height (km) detected by a ceilometer/lidar (black bars) and radiosondes (gray bars), and profiles of potential

Chemical and temperature profile data from CTD casts in the East China Sea, Sea of Japan, and North Pacific Ocean (NODC Accession 9700022)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Chemical and temperature profile data were collected from CTD casts in the East China Sea, Sea of Japan, and North Pacific Ocean. Data were submitted by the Japan...

Sources and burial fluxes of soot black carbon in sediments on the Mackenzie, Chukchi, and Bering Shelves

Science.gov (United States)

Yang, Weifeng; Guo, Laodong

2018-03-01

Black carbon (BC) has been recognized as a climate forcing and a major component in the global carbon budget. However, studies on BC in the Arctic Ocean remain scarce. We report here variations in the abundance, sources and burial fluxes of sedimentary soot black carbon (soot-BC) in the western Arctic Ocean. The soot-BC contents averaged 1.6 ± 0.3, 0.46 ± 0.04 and 0.56 ± 0.10 mg-C g-1 on the Mackenzie, Chukchi and Bering Shelves, respectively, accounting for 16.6%, 10.2% and 10.4% of the total organic carbon in surface sediment. Temporally, contents of soot-BC remained fairly stable before 1910, but increased rapidly after the 1970s on the Mackenzie Shelf, indicating enhanced source input related to warming. Comparable δ13C signatures of soot-BC (- 24.95‰ to - 24.57‰) to C3 plants pointed to a major biomass source of soot-BC to the Beaufort Sea. Soot-BC showed similar temporal patterns with large fluctuations in the Chukchi/Bering shelf regions, implying the same source terms for soot-BC in these areas. Two events with elevated soot-BC corresponded to a simultaneous increase in biomass combustion and fossil fuel (coal and oil) consumption in Asia. The similar temporal variability in sedimentary soot-BC between the Arctic shelves and Asian lakes and the comparable δ13C values manifested that anthropogenic emission from East Asia was an important source of soot-BC in the western Arctic and subarctic regions. The burial fluxes of soot-BC, estimated from both 137Cs- and 210Pb-derived sedimentation rates, were 2.43 ± 0.42 g-C m-2 yr-1 on the Mackenzie Shelf, representing an efficient soot-BC sink. Soot-BC showed an increase in buried fluxes from 0.56 ± 0.02 g-C m-2 yr-1 during 1963-1986 to 0.88 ± 0.05 g-C m-2 yr-1 after 1986 on the Chukchi Shelf, and from 1.00 ± 0.18 g-C m-2 yr-1 to 2.58 ± 1.70 g-C m-2 yr-1 on the Bering Shelf, which were consistent with recent anthropogenically enhanced BC input observed especially in Asia. Overall, the three Arctic

Assessment of EGM2008 using GPS/levelling and free-air gravity ...

African Journals Online (AJOL)

ge

gravity data over the oceans and point terrestrial gravity data. Details of the above data sets ... town of Mombasa in 1931 and the mean sea level determined using tidal data recorded for a period of one year (Aseno, 1995). ... The datum for height in Kenya is the mean sea level referred to a tide gauge at. Kilindini Harbour in ...

Coordinated Mapping of Sea Ice Deformation Features with Autonomous Vehicles

Science.gov (United States)

Maksym, T.; Williams, G. D.; Singh, H.; Weissling, B.; Anderson, J.; Maki, T.; Ackley, S. F.

2016-12-01

Decreases in summer sea ice extent in the Beaufort and Chukchi Seas has lead to a transition from a largely perennial ice cover, to a seasonal ice cover. This drives shifts in sea ice production, dynamics, ice types, and thickness distribution. To examine how the processes driving ice advance might also impact the morphology of the ice cover, a coordinated ice mapping effort was undertaken during a field campaign in the Beaufort Sea in October, 2015. Here, we present observations of sea ice draft topography from six missions of an Autonomous Underwater Vehicle run under different ice types and deformation features observed during autumn freeze-up. Ice surface features were also mapped during coordinated drone photogrammetric missions over each site. We present preliminary results of a comparison between sea ice surface topography and ice underside morphology for a range of sample ice types, including hummocked multiyear ice, rubble fields, young ice ridges and rafts, and consolidated pancake ice. These data are compared to prior observations of ice morphological features from deformed Antarctic sea ice. Such data will be useful for improving parameterizations of sea ice redistribution during deformation, and for better constraining estimates of airborne or satellite sea ice thickness.

A Universal Velocity Dispersion Profile for Pressure Supported Systems: Evidence for MONDian Gravity across Seven Orders of Magnitude in Mass

Energy Technology Data Exchange (ETDEWEB)

Durazo, R.; Hernandez, X.; Sánchez, S. F. [Instituto de Astronomía, Universidad Nacional Autónoma de México, Apartado Postal 70-264 C.P. 04510 México D.F., México (Mexico); Sodi, B. Cervantes [Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Campus Morelia, A.P. 3-72, C.P. 58089 Michoacán, México (Mexico)

2017-03-10

For any MONDian extended theory of gravity where the rotation curves of spiral galaxies are explained through a change in physics rather than the hypothesis of dark matter, a generic dynamical behavior is expected for pressure supported systems: an outer flattening of the velocity dispersion profile occurring at a characteristic radius, where both the amplitude of this flat velocity dispersion and the radius at which it appears are predicted to show distinct scalings with the total mass of the system. By carefully analyzing the dynamics of globular clusters and elliptical galaxies, we are able to significantly extend the astronomical diversity of objects in which MONDian gravity has been tested, from spiral galaxies to the much larger mass range covered by pressure supported systems. We show that a universal projected velocity dispersion profile accurately describes various classes of pressure supported systems, and further, that the expectations of extended gravity are met across seven orders of magnitude in mass. These observed scalings are not expected under dark matter cosmology, and would require particular explanations tuned at the scales of each distinct astrophysical system.

Arabian Sea GEOSECS stations revisited: Tracer-depth profiles reveal temporal variations?

International Nuclear Information System (INIS)

Mulsow, S.; Povinec, P.P.; Somayajulu, B.L.K.

2002-01-01

In March-April 1998, the Physical Research Laboratory and the Regional Research Laboratory (Ahmedabad, India) together with the IAEA Marine Environment Laboratory, Monaco, participated in the research mission to visit GEOSECS (Geochemical Ocean Sections Study) stations in the Arabian Sea. The main objective was to reoccupy these stations which were sampled in the early seventies to observe possible time variations in trace behaviour in this region. It is generally accepted that both natural (climate variations) and anthropogenic (greenhouse effect) changes can cause modifications of the oceanic characteristics and properties of deep waters on yearly and decadal scales. For long time-scales (100 to 1000 years) one needs to look at the sediments where these changes are subtly recorded. Tracers such as 14 C and 3 H (deep waters) and 228 Ra surface waters are useful markers of water circulation patterns and changes. Also man-made radiotracers such as 90 Sr, 137 Cs, 99 Tc, 238 Pu, 239 , 240 Pu and 241 Am, can give information on air-sea exchange as well as penetration (vertical change) rates in the open ocean [2]. We visited GEOSECS stations 415 to 419. In each station, CTD profiles, 3 H, 14 C, 90 Sr, 137 Cs, Pu and Am profiles, nutrients, Be, TOC and oxygen were determined from surface to bottom. Also uranium and trace elements were sampled in function of the oxygen minimum zone. In this paper we report the findings on the physical properties as well as the variations in water circulation patterns and also vertical exchange rates in the Arabian Sea. PSU profiles collected in this mission compared with those PSU profiles measured in 1974 (GEOSECS) showed marked differences in those stations located in the southeast part of the Arabian Sea. In contrast, those located more towards the north (415-416) showed little temporal variation. We think these changes may be real given that the PSU values at depth are comparable and reflect the presence of deep Antarctic bottom

Drift data of the sea-gravity meter (SL-2) installed on the R/V Hakurei-maru; `Hakureimaru` senjo jurokei (SL-2) no drift ni tsuite

Energy Technology Data Exchange (ETDEWEB)

Joshima, M [Geological Survey of Japan, Tsukuba (Japan); Ishihara, T [Japan National Oil Corp., Tokyo (Japan)

1996-05-01

This paper reports a rapid change in the drift of a sea-gravity meter SL-2 after 1987 and after its modification in 1993. In order to confirm the accuracy of the sea-gravity meter of the Hakurei-maru, changes in the lapse of time were summarized on the relative gravity value at the Funabashi base and on the drift rate in each voyage. The drift rates in the case of departing from and returning to Funabashi base were all less than 0.1mgal/day except the first year of 1987, which was presumably due to the growing stability of the gravimeter. The drift value of 1992 was 0.05mgal/day, producing an error of only 2mgal without drift compensation at the end of a 40 day voyage. The gravimeter after the total renewal of the control part in 1993 produced a large drift in the direction opposite to the conventional drift. The cause of these phenomena was supposed to be some kind of change in the spring property during the gap of one year; this large drift seemed to be settling down after the elapse of approximately one year. 4 refs., 8 figs., 2 tabs.

Glacier mass balance in high-arctic areas with anomalous gravity

Science.gov (United States)

Sharov, A.; Rieser, D.; Nikolskiy, D.

2012-04-01

All known glaciological models describing the evolution of Arctic land- and sea-ice masses in changing climate treat the Earth's gravity as horizontally constant, but it isn't. In the High Arctic, the strength of the gravitational field varies considerably across even short distances under the influence of a density gradient, and the magnitude of free air gravity anomalies attains 100 mGal and more. On long-term base, instantaneous deviations of gravity can have a noticeable effect on the regime and mass budget of glaciological objects. At best, the gravity-induced component of ice mass variations can be determined on topographically smooth, open and steady surfaces, like those of arctic planes, regular ice caps and landfast sea ice. The present research is devoted to studying gravity-driven impacts on glacier mass balance in the outer periphery of four Eurasian shelf seas with a very cold, dry climate and rather episodic character of winter precipitation. As main study objects we had chosen a dozen Russia's northernmost insular ice caps, tens to hundreds of square kilometres in extent, situated in a close vicinity of strong gravity anomalies and surrounded with extensive fields of fast and/or drift ice for most of the year. The supposition about gravitational forcing on glacioclimatic settings in the study region is based on the results of quantitative comparison and joint interpretation of existing glacier change maps and available data on the Arctic gravity field and solid precipitation. The overall mapping of medium-term (from decadal to half-centennial) changes in glacier volumes and quantification of mass balance characteristics in the study region was performed by comparing reference elevation models of study glaciers derived from Russian topographic maps 1:200,000 (CI = 20 or 40 m) representing the glacier state as in the 1950s-1980s with modern elevation data obtained from satellite radar interferometry and lidar altimetry. Free-air gravity anomalies were

PDEPTH—A computer program for the geophysical interpretation of magnetic and gravity profiles through Fourier filtering, source-depth analysis, and forward modeling

Science.gov (United States)

Phillips, Jeffrey D.

2018-01-10

PDEPTH is an interactive, graphical computer program used to construct interpreted geological source models for observed potential-field geophysical profile data. The current version of PDEPTH has been adapted to the Windows platform from an earlier DOS-based version. The input total-field magnetic anomaly and vertical gravity anomaly profiles can be filtered to produce derivative products such as reduced-to-pole magnetic profiles, pseudogravity profiles, pseudomagnetic profiles, and upward-or-downward-continued profiles. A variety of source-location methods can be applied to the original and filtered profiles to estimate (and display on a cross section) the locations and physical properties of contacts, sheet edges, horizontal line sources, point sources, and interface surfaces. Two-and-a-half-dimensional source bodies having polygonal cross sections can be constructed using a mouse and keyboard. These bodies can then be adjusted until the calculated gravity and magnetic fields of the source bodies are close to the observed profiles. Auxiliary information such as the topographic surface, bathymetric surface, seismic basement, and geologic contact locations can be displayed on the cross section using optional input files. Test data files, used to demonstrate the source location methods in the report, and several utility programs are included.

A gravity study along a profile across the Sichuan Basin, the Qinling Mountains and the Ordos Basin (central China): Density, isostasy and dynamics

Science.gov (United States)

Zhang, Yongqian; Teng, Jiwen; Wang, Qianshen; Lü, Qingtian; Si, Xiang; Xu, Tao; Badal, José; Yan, Jiayong; Hao, Zhaobing

2017-10-01

In order to investigate the structure of the crust beneath the Middle Qinling Mountains (MQL) and neighboring areas in the North China Block and South China Block, a north-south gravity profile from Yuquan in the Sichuan Basin to Yulin in the Ordos Basin was conducted in 2011. The Bouguer gravity anomaly is determined from a high-quality gravity dataset collected between 31°N and 36°N of latitude, and varies between -200 and -110 mGal in the study region. Using accredited velocity density relationships, an initial crust-mantle density model is constructed for MQL and adjacent areas, which is later refined interactively to simulate the observed gravity anomaly. The present study reveals the features of the density and Bouguer gravity with respect to the tectonic units sampled by the profile. The lithosphere density model shows typical density values that depict a layered structure and allow differentiate the blocks that extend along the reference profile. The gravity field calculated by forward modeling from the final density distribution model correlates well with the measured gravity field within a standard deviation of 1.26 mGal. The density in the crystalline crust increases with depth from 2.65 g/cm3 up to the highest value of 2.95 g/cm3 near the bottom of the crust. The Conrad interface is identified as a density jump of about 0.05 g/cm3. The average density of the crust in MQL is clearly lower than the density in the formations on both sides. Starting from a combined Airy-Pratt isostatic compensation model, a partly compensated crust is found below MQL, suggesting future growth of the crust, unlike the Ordos and Sichuan basins that will remain stable. On the basis of the density and isostatic state of the crust and additional seismological research, such as the P-wave velocity model and Poisson's ratio, it is concluded that the lower crust delamination is a reasonable interpretation for the geophysical characteristics below the Qinling Orogen.

Observing the seasonal cycle of the upper ocean in the Ross Sea, Antarctica, with autonomous profiling floats

Science.gov (United States)

Porter, D. F.; Springer, S. R.; Padman, L.; Fricker, H. A.; Bell, R. E.

2017-12-01

The upper layers of the Southern Ocean where it meets the Antarctic ice sheet undergoes a large seasonal cycle controlled by surface radiation and by freshwater fluxes, both of which are strongly influenced by sea ice. In regions where seasonal sea ice and icebergs limit use of ice-tethered profilers and conventional moorings, autonomous profiling floats can sample the upper ocean. The deployment of seven Apex floats (by sea) and six ALAMO floats (by air) provides unique upper ocean hydrographic data in the Ross Sea close to the Ross Ice Shelf front. A novel choice of mission parameters - setting parking depth deeper than the seabed - limits their drift, allowing us to deploy the floats close to the ice shelf front, while sea ice avoidance algorithms allow the floats to to sample through winter under sea ice. Hydrographic profiles show the detailed development of the seasonal mixed layer close to the Ross front, and interannual variability of the seasonal mixed layer and deeper water masses on the central Ross Sea continental shelf. After the sea ice breakup in spring, a warm and fresh surface mixed layer develops, further warming and deepening throughout the summer. The mixed layer deepens, with maximum temperatures exceeding 0ºC in mid-February. By March, the surface energy budget becomes negative and sea ice begins to form, creating a cold, saline and dense surface layer. Once these processes overcome the stable summer stratification, convection erodes the surface mixed layer, mixing some heat downwards to deeper layers. There is considerable interannual variability in the evolution and strength of the surface mixed layer: summers with shorter ice-free periods result in a cooler and shallower surface mixed layer, which accumulates less heat than the summers with longer ice-free periods. Early ice breakup occurred in all floats in 2016/17 summer, enhancing the absorbed solar flux leading to a warmer surface mixed layer. Together, these unique measurements from

Investigation of Range Profiles from a Simplified Ship on Rough Sea Surface and Its Multipath Imaging Mechanisms

Directory of Open Access Journals (Sweden)

Siyuan He

2012-01-01

Full Text Available The range profiles of a two-dimension (2 D perfect electric conductor (PEC ship on a wind-driven rough sea surface are derived by performing an inverse discrete Fourier transform (IDFT on the wide band backscattered field. The rough sea surface is assuming to be a PEC surface. The back scattered field is computed based on EM numerical simulation when the frequencies are sampled between 100 MHz and 700 MHz. Considering the strong coupling interactions between the ship and sea, the complicated multipath effect to the range profile characteristics is fully analyzed based on the multipath imaging mechanisms. The coupling mechanisms could be explained by means of ray theory prediction and numerical extraction of the coupling currents. The comparison of the range profile locations between ray theory prediction and surface current simulation is implemented and analyzed in this paper. Finally, the influence of different sea states on the radar target signatures has been examined and discussed.

A three-dimensional geophysical model of the crust in the Barents Sea region: Model construction and basement characterization

Science.gov (United States)

Ritzmann, O.; Maercklin, N.; Inge, Faleide J.; Bungum, H.; Mooney, W.D.; Detweiler, S.T.

2007-01-01

BARENTS50, a new 3-D geophysical model of the crust in the Barents Sea Region has been developed by the University of Oslo, NORSAR and the U.S. Geological Survey. The target region comprises northern Norway and Finland, parts of the Kola Peninsula and the East European lowlands. Novaya Zemlya, the Kara Sea and Franz-Josef Land terminate the region to the east, while the Norwegian-Greenland Sea marks the western boundary. In total, 680 1-D seismic velocity profiles were compiled, mostly by sampling 2-D seismic velocity transects, from seismic refraction profiles. Seismic reflection data in the western Barents Sea were further used for density modelling and subsequent density-to-velocity conversion. Velocities from these profiles were binned into two sedimentary and three crystalline crustal layers. The first step of the compilation comprised the layer-wise interpolation of the velocities and thicknesses. Within the different geological provinces of the study region, linear relationships between the thickness of the sedimentary rocks and the thickness of the remaining crystalline crust are observed. We therefore, used the separately compiled (area-wide) sediment thickness data to adjust the total crystalline crustal thickness according to the total sedimentary thickness where no constraints from 1-D velocity profiles existed. The BARENTS50 model is based on an equidistant hexagonal grid with a node spacing of 50 km. The P-wave velocity model was used for gravity modelling to obtain 3-D density structure. A better fit to the observed gravity was achieved using a grid search algorithm which focussed on the density contrast of the sediment-basement interface. An improvement compared to older geophysical models is the high resolution of 50 km. Velocity transects through the 3-D model illustrate geological features of the European Arctic. The possible petrology of the crystalline basement in western and eastern Barents Sea is discussed on the basis of the observed seismic

Pressure Profiles in a Loop Heat Pipe under Gravity Influence

Science.gov (United States)

Ku, Jentung

2015-01-01

During the operation of a loop heat pipe (LHP), the viscous flow induces pressure drops in various elements of the loop. The total pressure drop is equal to the sum of pressure drops in vapor grooves, vapor line, condenser, liquid line and primary wick, and is sustained by menisci at liquid and vapor interfaces on the outer surface of the primary wick in the evaporator. The menisci will curve naturally so that the resulting capillary pressure matches the total pressure drop. In ground testing, an additional gravitational pressure head may be present and must be included in the total pressure drop when LHP components are placed in a non-planar configuration. Under gravity-neutral and anti-gravity conditions, the fluid circulation in the LHP is driven solely by the capillary force. With gravity assist, however, the flow circulation can be driven by the combination of capillary and gravitational forces, or by the gravitational force alone. For a gravity-assist LHP at a given elevation between the horizontal condenser and evaporator, there exists a threshold heat load below which the LHP operation is gravity driven and above which the LHP operation is capillary force and gravity co-driven. The gravitational pressure head can have profound effects on the LHP operation, and such effects depend on the elevation, evaporator heat load, and condenser sink temperature. This paper presents a theoretical study on LHP operations under gravity-neutral, anti-gravity, and gravity-assist modes using pressure diagrams to help understand the underlying physical processes. Effects of the condenser configuration on the gravitational pressure head and LHP operation are also discussed.

Investigating gravity waves evidences in the Venus upper atmosphere

Science.gov (United States)

Migliorini, Alessandra; Altieri, Francesca; Shakun, Alexey; Zasova, Ludmila; Piccioni, Giuseppe; Bellucci, Giancarlo; Grassi, Davide

2014-05-01

We present a method to investigate gravity waves properties in the upper mesosphere of Venus, through the O2 nightglow observations acquired with the imaging spectrometer VIRTIS on board Venus Express. Gravity waves are important dynamical features that transport energy and momentum. They are related to the buoyancy force, which lifts air particles. Then, the vertical displacement of air particles produces density changes that cause gravity to act as restoring force. Gravity waves can manifest through fluctuations on temperature and density fields, and hence on airglow intensities. We use the O2 nightglow profiles showing double peaked structures to study the influence of gravity waves in shaping the O2 vertical profiles and infer the waves properties. In analogy to the Earth's and Mars cases, we use a well-known theory to model the O2 nightglow emissions affected by gravity waves propagation. Here we propose a statistical discussion of the gravity waves characteristics, namely vertical wavelength and wave amplitude, with respect to local time and latitude. The method is applied to about 30 profiles showing double peaked structures, and acquired with the VIRTIS/Venus Express spectrometer, during the mission period from 2006-07-05 to 2008-08-15.

Bouguer gravity and crustal structure of the Dead Sea transform fault and adjacent mountain belts in Lebanon

Science.gov (United States)

Kamal; Khawlie, Mohamad; Haddad, Fuad; Barazangi, Muawia; Seber, Dogan; Chaimov, Thomas

1993-08-01

The northern extension of the Dead Sea transform fault in southern Lebanon bifurcates into several faults that cross Lebanon from south to north. The main strand, the Yammouneh fault, marks the boundary between the Levantine (eastern Mediterranean) and Arabian plates and separates the western mountain range (Mount Lebanon) from the eastern mountain range (Anti-Lebanon). Bouguer gravity contours in Lebanon approximately follow topographic contours; i.e., positive Bouguer anomalies are associated with the Mount Lebanon and Anti-Lebanon ranges. This suggests that the region is not in simple isostatic compensation. Gravity observations based on 2.5-dimensional modeling and other available geological and geophysical information have produced the following interpretations. (1) The crust of Lebanon thins from ˜35 km beneath the Anti-Lebanon range, near the Syrian border, to ˜27 km beneath the Lebanese coast. No crustal roots exist beneath the Lebanese ranges. (2) The depth to basement is ˜3.5-6 km below sea level under the ranges and is ˜8-10 km beneath the Bekaa depression. (3) The Yammouneh fault bifurcates northward into two branches; one passes beneath the Yammouneh Lake through the eastern part of Mount Lebanon and another bisects the northern part of the Bekaa Valley (i.e., Mid-Bekaa fault). The Lebanese mountain ranges and the Bekaa depression were formed as a result of transtension and later transpression associated with the relative motion of a few crustal blocks in response to the northward movement of the Arabian plate relative to the Levantine plate.

Changes provoked by boiling, steaming and sous-vide cooking in the lipid and volatile profile of European sea bass.

Science.gov (United States)

Nieva-Echevarría, Bárbara; Manzanos, María J; Goicoechea, Encarnación; Guillén, María D

2017-09-01

This study aims to shed light on the changes provoked by boiling, steaming and sous-vide cooking on the lipids and volatile profile of farmed and wild European sea bass meat. None of the cooking techniques provoked changes due to hydrolytic or oxidation processes detectable by 1 H NMR on sea bass lipids. The lipid profile of main and minor lipidic components was maintained after cooking. However, study by SPME-GC/MS evidenced that steaming and sous-vide cooking modified the volatile profile of sea bass meat, especially in farmed specimens. The compounds generated came from the occurrence, to a very small extent, of lipid and protein degradation. By contrast, boiling scarcely modified the initial characteristics of raw sea bass. Thus, from a sensory point of view and considering the odour-active compounds generated, steaming and sous-vide cooking provoked more noticeable changes than boiling, especially in farmed sea bass meat. Copyright © 2017. Published by Elsevier Ltd.

Gravity field and structure of the Sorong Fault Zone, eastern Indonesia

Science.gov (United States)

Sardjono

Gravity surveys along coastlines of islands in the region Banggai-Sula, Eastern Sulawesi, Halmahera, Bacan and Obi were carried out as part of the Sorong Fault Zone Project. Results of the Surveys were integrated with gravity data previously acquired by other projects, including on-land gravity data from the Bird Head area Irian Jaya (Dow et al 1986), Seram Island (Milsom 1977), Buru Island (Oemar and Reminton 1993) and Central Sulawesi (Silver et al. 1983) as well as marine gravity information within and surrounding the Sorong Fault Zone (Bowin et al. 1980). Gravity expeditions of the Sorong Fault Zone Project also include measurements in Mayu Island and the island group of Talaud, situated further north in the Central Molucca Sea region. A total of one hundred and forty two gravity data were acquired in the region of Banggai-Sula islands, forty seven in eastern part of Central Sulawesi, about four hundred in Halmahera, Bacan and Obi, and seventy nine in Mayu and Talaud. Surveys in the eastern part of Central Sulawesi were carried out for the purpose of tieing the older gravity data obtained from Silver et al. (1983) and the more recent data of the Sorong Fault Zone Project. About one thousand thirty hundred and thirty gravity data were acquired as part of the Irian Jaya Geological Mapping Project (IJGMP) in the period of 1978-1983, a project commissioned by the Indonesian Geological Research and Development Centre (GRDC) and the Australian Bureau of Mineral Resources (BMR). The remoteness of the survey areas of the Sorong Fault Zone Project necessitated a careful planning for travel arrangements and provision of logistics. A wide range of magnitude of gravity field was observed in the Sorong Fault Zone, extending from values below -250 mGal recorded in the southern part of the Molucca Sea to values in excess of +320 mGal measured near to sea level in the coastal areas south of Mangole and north of Sulabesi, the two islands of the Sula Group. Steep gradients of

Joint inversion of gravity and seismic data along a profile across the seismogenic fault of 2010 Yushu Ms7.1 earthquake

Directory of Open Access Journals (Sweden)

Yang Guangliang

2011-11-01

Full Text Available Yushu Ms7.1 earthquake occurred on the Ganzi-Yushu fault zone, across which we carried out a joint relative-gravity and seismic-reflection survey, and then performed a gravity inversion constrained by the seismic-reflection result. Based on the data of complete Bouguer gravity anomaly and seismic reflection, we obtained a layered interface structure in deep crust down to Moho. Our study showed that the inversion could reveal the interfaces of strata along the survey profile and the directions of regional faults in two-dimension. From the characteristics of the observed topography of the Moho basement, we tentatively confirmed that the uplift of eastern edge of Qinghai-Tibet plateau was caused by the subduction of the Indian plate.

Interpretation of gravity profiles across the northern Oaxaca terrane, its boundaries and the Tehuacán Valley, southern Mexico

Science.gov (United States)

Campos-Enríquez, J. O.; Alatorre-Zamora, M. A.; Keppie, J. D.; Belmonte-Jiménez, S. I.; Ramón-Márquez, V. M.

2014-12-01

A gravity study was conducted across the northern Oaxaca terrane and its bounding faults: the Caltepec and Oaxaca Faults to the west and east, respectively. These faults juxtapose the Oaxaca terrane against the Mixteca and Juarez terranes, respectively. The Oaxaca Fault also forms the eastern boundary of the Cenozoic Tehuacán depression. On the west, at depth, the Tehuacán valley is limited by the normal buried Tehuacán Fault. This gravity study reveals that the Oaxaca Fault system gives rise to a series of east tilted basamental blocks (Oaxaca Complex). The tectonic depression is filled with Phanerozoic rocks and has a deeper depocenter to the west. The gravity data also indicate that on the west, the Oaxaca Complex, the Caltepec and Santa Lucia faults continue northwestwards beneath Phanerozoic rocks. A major E-W to NE-SW discontinuity is inferred to exist between profiles 1 and 2.

Detailed gravity survey to help seismic microzonation: Mapping the thickness of unconsolidated deposits in Ottawa, Canada

Science.gov (United States)

Lamontagne, M.; Thomas, M.; Silliker, J.; Jobin, D.

2011-11-01

In this study, measurements of gravity were made to map and model the thickness of Quaternary deposits (sand and clay) overlying Ordovician limestones in a suburb of Ottawa (Orléans, Ontario). Because ground motion amplification is partly related to the thickness of unconsolidated deposits, this work helps refine the assessment of the earthquake damage potential of the area. It also helps the mapping of clay basins, which can locally exceed 100 m in thickness, where ground motion amplification can occur. Previous work, including well log data and seismic methods, have yielded a wealth of information on near-surface geology in Orléans, thereby providing the necessary constraints to test the applicability of gravity modeling in other locations where other methods cannot always be used. Some 104 gravity stations were occupied in an 8 × 12 km test area in the Orléans. Stations were accurately located with differential GPS that provided centimetric accuracy in elevation. Densities of the unconsolidated Quaternary deposits (Champlain Sea clay) determined on core samples and densities determined on limestone samples from outcrops were used to constrain models of the clay layer overlying the higher density bedrock formations (limestone). The gravity anomaly map delineates areas where clay basins attain > 100 m depth. Assuming a realistic density for the Champlain Sea clays (1.9-2.1 g/cm 3), the thickness over the higher density bedrock formations (Ordovician carbonate rocks) was modeled and compared with well logs and two seismic reflection profiles. The models match quite well with the information determined from well logs and seismic methods. It was found that gravity and the thickness of unconsolidated deposits are correlated but the uncertainties in both data sets preclude the definition of a direct correlation between the two. We propose that gravity measurements at a local scale be used as an inexpensive means of mapping the thickness of unconsolidated deposits

CLASH-VLT: testing the nature of gravity with galaxy cluster mass profiles

Energy Technology Data Exchange (ETDEWEB)

Pizzuti, L.; Sartoris, B.; Borgani, S.; Girardi, M. [Dipartimento di Fisica, Sezione di Astronomia, Università di Trieste, Via Tiepolo 11, I-34143 Trieste (Italy); Amendola, L. [Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 16, D-69120 Heidelberg (Germany); Umetsu, K. [5 Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); Biviano, A.; Balestra, I.; Nonino, M. [INAF—Osservatorio Astronomico di Trieste, Via Tiepolo 11, I-34143 Trieste (Italy); Rosati, P. [University Observatory Munich, Scheinerstrasse 1, D-81679 Mu\\' nchen (Germany); Caminha, G.B. [Dipartimento di Fisica e Scienze della Terra, Università di Ferrara, Via Saragat 1, I-44122 Ferrara (Italy); Frye, B. [Steward Observatory/Department of Astronomy, University of Arizona, 933 N Cherry Ave, Tucson, AZ 85721 (United States); Koekemoer, A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Grillo, C. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Lombardi, M. [Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, I-20133 Milan (Italy); Mercurio, A., E-mail: pizzuti@oats.inaf.it, E-mail: barbara.sartoris@gmail.com, E-mail: borgani@oats.inaf.it, E-mail: l.amendola@thphys.uniheidelberg.de [Osservatorio Astronomico di Capodimonte, Via Moiariello 16, I-80131 Napoli (Italy)

2016-04-01

We use high-precision kinematic and lensing measurements of the total mass profile of the dynamically relaxed galaxy cluster MACS J1206.2-0847 at z=0.44 to estimate the value of the ratio η=Ψ/Φ between the two scalar potentials in the linear perturbed Friedmann-Lemaitre-Robertson-Walker metric. An accurate measurement of this ratio, called anisotropic stress, could show possible, interesting deviations from the predictions of the theory of General Relativity, according to which Ψ should be equal to Φ. Complementary kinematic and lensing mass profiles were derived from exhaustive analyses using the data from the Cluster Lensing And Supernova survey with Hubble (CLASH) and the spectroscopic follow-up with the Very Large Telescope (CLASH-VLT). Whereas the kinematic mass profile tracks only the time-time part of the perturbed metric (i.e. only Φ), the lensing mass profile reflects the contribution of both time-time and space-space components (i.e. the sum Φ+Ψ). We thus express η as a function of the mass profiles and perform our analysis over the radial range 0.5 Mpc≤ r≤ r{sub 200}=1.96 Mpc. Using a spherical Navarro-Frenk-White mass profile, which well fits the data, we obtain η(r{sub 200})=1.01 {sub −0.28}{sup +0.31} at the 68% C.L. We discuss the effect of assuming different functional forms for mass profiles and of the orbit anisotropy in the kinematic reconstruction. Interpreting this result within the well-studied f(R) modified gravity model, the constraint on η translates into an upper bound to the interaction length (inverse of the scalaron mass) smaller than 2 Mpc. This tight constraint on the f(R) interaction range is however substantially relaxed when systematic uncertainties in the analysis are considered. Our analysis highlights the potential of this method to detect deviations from general relativity, while calling for the need of further high-quality data on the total mass distribution of clusters and improved control on systematic

Variations of transcript profiles between sea otters Enhydra lutris from Prince William Sound, Alaska, and clinically normal reference otters

Science.gov (United States)

Miles, A. Keith; Bowen, Lizabeth; Ballachey, Brenda E.; Bodkin, James L.; Murray, M.; Estes, J.L.; Keister, Robin A.; Stott, J.L.

2012-01-01

Development of blood leukocyte gene transcript profiles has the potential to expand condition assessments beyond those currently available to evaluate wildlife health, including sea otters Enhydra lutris, both individually and as populations. The 10 genes targeted in our study represent multiple physiological systems that play a role in immuno-modulation, inflammation, cell protection, tumor suppression, cellular stress-response, xenobiotic metabolizing enzymes, and antioxidant enzymes. These genes can be modified by biological, physical, or anthropogenic impacts and consequently provide information on the general type of stressors present in a given environment. We compared gene transcript profiles of sea otters sampled in 2008 among areas within Prince William Sound impacted to varying degrees by the 1989 ‘Exxon Valdez’ oil spill with those of captive and wild reference sea otters. Profiles of sea otters from Prince William Sound showed elevated transcription in genes associated with tumor formation, cell death, organic exposure, inflammation, and viral exposure when compared to the reference sea otter group, indicating possible recent and chronic exposure to organic contaminants. Sea otters from historically designated oiled areas within Prince William Sound 19 yr after the oil spill had higher transcription of genes associated with tumor formation, cell death, heat shock, and inflammation than those from areas designated as less impacted by the spill.

Arctic ice island and sea ice movements and mechanical properties. First quarterly report, October 1-December 31, 1983

Energy Technology Data Exchange (ETDEWEB)

Sackinger, W.M.; Stringer, W.J.

1984-01-01

Research activities for the first quarter are presented for the following tasks: (1) ice island; (2) intrusion of the pack ice edge in the Chukchi Sea; and (3) spray ice adhesion to offshore structure coatings. With respect to the ice island portion of this project the following activities are planned for the year: (1) use aerial photography, satellite imagery, and all available historical records to establish a time history of all of the ice shelves of Ellesmere Island; (2) establish positioning buoys on the existing ice islands to track their trajectories daily and to telemeter daily barometric pressure and temperature, via System Argos; (3) relate geostrophic winds to the observed trajectories; (4) begin to build a pseudo-random model for ice island motion over the long term which would enable a determination of the probability of interaction between ice islands and offshore structures. The overall objective of task 2 is to investigate and analyze the causes and extent of summer time pace ice intrusions into the Chukchi Sea, which would interfere with exploration drilling and emplacement of permanent production structures. For task three a method for evaluating shear and tensile strengths of the interface bond between the sea spray ice layer and the structure or ship surface will be developed. A second more detailed task is to then measure the mechanical properties of this bonded layer for a variety of candidate coatings, as functions of temperature, loading rate, strain rate, salinity, and ice type. 25 references, 92 figures.

Gravity inferred subsurface structure of Gadwal schist belt, Andhra ...

Indian Academy of Sciences (India)

residual gravity profile data were interpreted using 2-D prism models. The results ... Geological and geophysical layout map of the Gadwal schist belt area, Andhra Pradesh (after Ananda Murty and ... Observed gravity (Bouguer) values, regional, residual and inferred gravity models along traverse I of the Gadwal schist.

Temperature profile data collected aboard the USCGC Polar Star in support of investigations of the influence of the Mendeleev Ridge and Chukchi Borderland on the large-scale circulation of the Arctic Ocean, August - September 2002 (NODC Accession 0002697)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This is an archive of data of 47 distinct XBT casts taken at 41 locations in the Mendeleev Ridge and Chukchi Borderland region of the Arctic between 22nd August and...

Barents Sea Crustal and Upper Mantle Structure from Deep Seismic and Potential Field Data

Science.gov (United States)

Aarseth, I.; Mjelde, R.; Breivik, A. J.; Minakov, A.; Huismans, R. S.; Faleide, J. I.

2016-12-01

The Barents Sea basement comprises at least two different domains; the Caledonian in the west and the Timanian in the east. Contrasting interpretations have been published recently, as the transition between these two domains is not well constrained. Interpretations of new high-quality magnetic data covering most of the SW Barents Sea challenged previous studies of the Late Paleozoic basin configurations in the western and central Barents Sea. Two major directions of Caledonian structures have been proposed by different authors: N-S and SW-NE. Two regional ocean bottom seismic (OBS) profiles, crossing these two major directions, were acquired in 2014.The primary goal in this project is to locate the main Caledonian suture in the western Barents Sea, as well as the possible Barentsia-Baltica suture postulated further eastwards. High velocity anomalies associated with Caledonian eclogites are particularly interesting as they may be related to Caledonian suture zones. The collapse of the Caledonian mountain range predominantly along these suture zones is expected to be closely linked to the deposition of Devonian erosional products, and subsequent rifting is likely to be influenced by inheritance of Caledonian trends. P-wave travel-time modelling is done by use of a combined ray-tracing and inversion scheme, and gravity modelling has been used to support the seismic model. The results indicate high P-wave velocities (mostly over 4 km/s) close to the seafloor as well as high velocity (around 6 km/s) zones at shallow depths which are interpreted as volcanic sills. The crustal transect reveals areas of complex geology and velocity inversions. Strong reflections from within the crystalline crust indicate a heterogeneous basement terrain. Gravity modelling agrees with this, as several blocks with variable densities had to be introduced in order to reproduce the observed gravity anomalies. Refractions from the top of the crystalline basement together with reflections from

New standards for reducing gravity data: The North American gravity database

Science.gov (United States)

Hinze, W. J.; Aiken, C.; Brozena, J.; Coakley, B.; Dater, D.; Flanagan, G.; Forsberg, R.; Hildenbrand, T.; Keller, Gordon R.; Kellogg, J.; Kucks, R.; Li, X.; Mainville, A.; Morin, R.; Pilkington, M.; Plouff, D.; Ravat, D.; Roman, D.; Urrutia-Fucugauchi, J.; Veronneau, M.; Webring, M.; Winester, D.

2005-01-01

The North American gravity database as well as databases from Canada, Mexico, and the United States are being revised to improve their coverage, versatility, and accuracy. An important part of this effort is revising procedures for calculating gravity anomalies, taking into account our enhanced computational power, improved terrain databases and datums, and increased interest in more accurately defining long-wavelength anomaly components. Users of the databases may note minor differences between previous and revised database values as a result of these procedures. Generally, the differences do not impact the interpretation of local anomalies but do improve regional anomaly studies. The most striking revision is the use of the internationally accepted terrestrial ellipsoid for the height datum of gravity stations rather than the conventionally used geoid or sea level. Principal facts of gravity observations and anomalies based on both revised and previous procedures together with germane metadata will be available on an interactive Web-based data system as well as from national agencies and data centers. The use of the revised procedures is encouraged for gravity data reduction because of the widespread use of the global positioning system in gravity fieldwork and the need for increased accuracy and precision of anomalies and consistency with North American and national databases. Anomalies based on the revised standards should be preceded by the adjective "ellipsoidal" to differentiate anomalies calculated using heights with respect to the ellipsoid from those based on conventional elevations referenced to the geoid. ?? 2005 Society of Exploration Geophysicists. All rights reserved.

Towards unification of terrestrial gravity data sets in Estonia

Directory of Open Access Journals (Sweden)

Ellmann, Artu

2009-12-01

Full Text Available Gravity data in Estonia have been collected by different institutions over many decades. This study assesses the suitability of available gravity data for ensuring a 1 cm geoid modelling accuracy over Estonia and in the Baltic Sea region in general. The main focus of this study is on the determination and elimination of discrepancies between three nationwide datasets. It was detected that one tested historic gravity dataset contained inadmissible systematic biases with respect to other tested datasets. Possible ways of gravity data improvement are discussed. More specifically, new field observation campaigns and aspects of using their outcomes in subsequent regional geoid modelling are suggested.

The use of gravity methods in the internal characterization of landfills—a case study

International Nuclear Information System (INIS)

Mantlík, František; Matias, Manuel; Grangeia, Carlos; Tareco, Hélder; Lourenço, Jose

2009-01-01

Some examples of the use of gravity exploration methods in landfills were published recently. However, density contrast between the landfill and the host media as well as the cost involved may be limiting factors to the application of gravimetry to this problem. Herein a case study of the application of gravity methods to the internal characterization of a sealed landfill is presented. This landfill is installed in recent low-density quaternary sand formations. Two north–south gravity profiles were carried out. The first profile crossed the landfill at its centre, whilst a second profile was done some distance away from the landfill to provide general regional information. The first profile was modelled in order to obtain lateral variations of density within the landfill that might be caused by different types of waste and/or the age of the waste deposits. Gravity modelling and interpretation were supported with data from resistivity profiles carried out in the immediate vicinity of the gravity measurements, i.e. the resistivity profiles interpretation results constrained the thickness of landfill deposits

Impact of water temperature on the growth and fatty acid profiles of juvenile sea cucumber Apostichopus japonicus (Selenka).

Science.gov (United States)

Yu, Haibo; Zhang, Cheng; Gao, Qinfeng; Dong, Shuanglin; Ye, Zhi; Tian, Xiangli

2016-08-01

The present study determined the changes in the fatty acid (FA) profiles of juvenile sea cucumber Apostichopus japonicus in response to the varied water temperature. Sea cucumbers with similar size (4.02±0.11g) were cultured for 8 weeks at 14°C, 18°C, 22°C and 26°C, respectively. At the end of the experiment, the specific growth rate (SGR) and the profiles of FAs in neutral lipids and phospholipids of the juvenile sea cucumbers cultured at different temperatures were determined. The SGRs of the sea cucumbers cultured at 26°C significantly decreased 46.3% compared to thos cultured at 18°C. Regression analysis showed that the SGR-temperature (T) relationship can be expressed as SGR=-0.0073T(2)+0.255T -1.0231 (R(2)=0.9936) and the highest SGR was predicted at 17.5°C. For the neutral lipids, the sum of saturated FAs (SFAs), monounsaturated FAs (MUFAs) or polyunsaturated FAs (PUFAs) of the sea cucumbers that were cultured at the water temperature from 18°C-26°C did not change significantly, indicating the insensitivity of FA profiles for the neutral lipids of sea cucumbers in response to increasing water temperature. For phospholipids, the sum of PUFAs in the sea cucumbers dramatically decreased with the gradually increased water temperature. The sum of SFAs and MUFAs of sea cucumbers, however, increased with the gradually elevated water temperature. In particular, the contents of highly unsaturated fatty acids (HUFAs), including eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA), in the phospholipids of the sea cucumbers decreased 37.2% and 26.1%, respectively, when the water temperature increased from 14°C to 26°C. In summary, the sea cucumbers A. japonicus can regulate the FA compositions, especially the contents of EPA and DHA, in the phospholipids so as to adapt to varied water temperature. Copyright © 2016 Elsevier Ltd. All rights reserved.

Invariant polar bear habitat selection during a period of sea ice loss.

Science.gov (United States)

Wilson, Ryan R; Regehr, Eric V; Rode, Karyn D; St Martin, Michelle

2016-08-17

Climate change is expected to alter many species' habitat. A species' ability to adjust to these changes is partially determined by their ability to adjust habitat selection preferences to new environmental conditions. Sea ice loss has forced polar bears (Ursus maritimus) to spend longer periods annually over less productive waters, which may be a primary driver of population declines. A negative population response to greater time spent over less productive water implies, however, that prey are not also shifting their space use in response to sea ice loss. We show that polar bear habitat selection in the Chukchi Sea has not changed between periods before and after significant sea ice loss, leading to a 75% reduction of highly selected habitat in summer. Summer was the only period with loss of highly selected habitat, supporting the contention that summer will be a critical period for polar bears as sea ice loss continues. Our results indicate that bears are either unable to shift selection patterns to reflect new prey use patterns or that there has not been a shift towards polar basin waters becoming more productive for prey. Continued sea ice loss is likely to further reduce habitat with population-level consequences for polar bears. © 2016 The Author(s).

Invariant polar bear habitat selection during a period of sea ice loss

Science.gov (United States)

Wilson, Ryan R.; Regehr, Eric V.; Rode, Karyn D.; St Martin, Michelle

2016-01-01

Climate change is expected to alter many species' habitat. A species' ability to adjust to these changes is partially determined by their ability to adjust habitat selection preferences to new environmental conditions. Sea ice loss has forced polar bears (Ursus maritimus) to spend longer periods annually over less productive waters, which may be a primary driver of population declines. A negative population response to greater time spent over less productive water implies, however, that prey are not also shifting their space use in response to sea ice loss. We show that polar bear habitat selection in the Chukchi Sea has not changed between periods before and after significant sea ice loss, leading to a 75% reduction of highly selected habitat in summer. Summer was the only period with loss of highly selected habitat, supporting the contention that summer will be a critical period for polar bears as sea ice loss continues. Our results indicate that bears are either unable to shift selection patterns to reflect new prey use patterns or that there has not been a shift towards polar basin waters becoming more productive for prey. Continued sea ice loss is likely to further reduce habitat with population-level consequences for polar bears.

Venus - Ishtar gravity anomaly

Science.gov (United States)

Sjogren, W. L.; Bills, B. G.; Mottinger, N. A.

1984-01-01

The gravity anomaly associated with Ishtar Terra on Venus is characterized, comparing line-of-sight acceleration profiles derived by differentiating Pioneer Venus Orbiter Doppler residual profiles with an Airy-compensated topographic model. The results are presented in graphs and maps, confirming the preliminary findings of Phillips et al. (1979). The isostatic compensation depth is found to be 150 + or - 30 km.

Wind Profiles and Wave Spectra for Potential Wind Farms in South China Sea. Part II: Wave Spectrum Model

Directory of Open Access Journals (Sweden)

Yichao Liu

2017-01-01

Full Text Available Along with the commercialization of offshore wind energy in China, the South China Sea has been identified as ideal for constructing offshore wind farms, especially for farms consisting of floating wind turbines over deep waters. Since the wind profiles and wave spectra are somewhat primitive for the design of an offshore wind turbine, engineering models describing the wind and wave characteristics in the South China Sea area are necessary for the offshore wind energy exploitation given the meteorological, hydrological, and geographical differences between the South China Sea and the North/Norwegian Sea, where the commonly used wind profile and wave spectrum models were designated. In the present study; a series of numerical simulations were conducted to reveal the wave characteristics in the South China Sea under both typhoon and non-typhoon conditions. By analyzing the simulation results; the applicability of the Joint North Sea Wave Project (JONSWAP spectrum model; in terms of characterizing the wind-induced wave fields in the South China Sea; was discussed. In detail; the key parameters of the JONSWAP spectrum model; such as the Phillips constant; spectral width parameter; peak-enhancement factor, and high frequency tail decay; were investigated in the context of finding suitable values.

Collaborations for Arctic Sea Ice Information and Tools

Science.gov (United States)

Sheffield Guy, L.; Wiggins, H. V.; Turner-Bogren, E. J.; Rich, R. H.

2017-12-01

The dramatic and rapid changes in Arctic sea ice require collaboration across boundaries, including between disciplines, sectors, institutions, and between scientists and decision-makers. This poster will highlight several projects that provide knowledge to advance the development and use of sea ice knowledge. Sea Ice for Walrus Outlook (SIWO: https://www.arcus.org/search-program/siwo) - SIWO is a resource for Alaskan Native subsistence hunters and other interested stakeholders. SIWO provides weekly reports, during April-June, of sea ice conditions relevant to walrus in the northern Bering and southern Chukchi seas. Collaboration among scientists, Alaskan Native sea-ice experts, and the Eskimo Walrus Commission is fundamental to this project's success. Sea Ice Prediction Network (SIPN: https://www.arcus.org/sipn) - A collaborative, multi-agency-funded project focused on seasonal Arctic sea ice predictions. The goals of SIPN include: coordinate and evaluate Arctic sea ice predictions; integrate, assess, and guide observations; synthesize predictions and observations; and disseminate predictions and engage key stakeholders. The Sea Ice Outlook—a key activity of SIPN—is an open process to share and synthesize predictions of the September minimum Arctic sea ice extent and other variables. Other SIPN activities include workshops, webinars, and communications across the network. Directory of Sea Ice Experts (https://www.arcus.org/researchers) - ARCUS has undertaken a pilot project to develop a web-based directory of sea ice experts across institutions, countries, and sectors. The goal of the project is to catalyze networking between individual investigators, institutions, funding agencies, and other stakeholders interested in Arctic sea ice. Study of Environmental Arctic Change (SEARCH: https://www.arcus.org/search-program) - SEARCH is a collaborative program that advances research, synthesizes research findings, and broadly communicates the results to support

Mexico Gravity Data per 2 min Cell (97)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This 2' gravity density grid for Mexico, North-Central America, and the Western Caribbean Sea shows the distribution of about one million terrestrial and marine...

Astrophysical black holes in screened modified gravity

Energy Technology Data Exchange (ETDEWEB)

Davis, Anne-Christine; Jha, Rahul; Muir, Jessica [Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA (United Kingdom); Gregory, Ruth, E-mail: acd@damtp.cam.ac.uk, E-mail: r.a.w.gregory@durham.ac.uk, E-mail: r.jha@damtp.cam.ac.uk, E-mail: jlmuir@umich.edu [Centre for Particle Theory, South Road, Durham, DH1 3LE (United Kingdom)

2014-08-01

Chameleon, environmentally dependent dilaton, and symmetron gravity are three models of modified gravity in which the effects of the additional scalar degree of freedom are screened in dense environments. They have been extensively studied in laboratory, cosmological, and astrophysical contexts. In this paper, we present a preliminary investigation into whether additional constraints can be provided by studying these scalar fields around black holes. By looking at the properties of a static, spherically symmetric black hole, we find that the presence of a non-uniform matter distribution induces a non-constant scalar profile in chameleon and dilaton, but not necessarily symmetron gravity. An order of magnitude estimate shows that the effects of these profiles on in-falling test particles will be sub-leading compared to gravitational waves and hence observationally challenging to detect.

Astrophysical black holes in screened modified gravity

International Nuclear Information System (INIS)

Davis, Anne-Christine; Jha, Rahul; Muir, Jessica; Gregory, Ruth

2014-01-01

Chameleon, environmentally dependent dilaton, and symmetron gravity are three models of modified gravity in which the effects of the additional scalar degree of freedom are screened in dense environments. They have been extensively studied in laboratory, cosmological, and astrophysical contexts. In this paper, we present a preliminary investigation into whether additional constraints can be provided by studying these scalar fields around black holes. By looking at the properties of a static, spherically symmetric black hole, we find that the presence of a non-uniform matter distribution induces a non-constant scalar profile in chameleon and dilaton, but not necessarily symmetron gravity. An order of magnitude estimate shows that the effects of these profiles on in-falling test particles will be sub-leading compared to gravitational waves and hence observationally challenging to detect

Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from BARUNA JAYA IV in the Banda Sea, Ceram Sea or Seram Sea and others from 1998-02-19 to 1998-03-05 (NCEI Accession 0157460)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0157460 includes chemical, discrete sample, physical and profile data collected from BARUNA JAYA IV in the Banda Sea, Ceram Sea or Seram Sea, Flores...

Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from BARUNA JAYA IV in the Banda Sea, Ceram Sea or Seram Sea and others from 1996-11-21 to 1996-12-13 (NCEI Accession 0157473)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0157473 includes chemical, discrete sample, physical and profile data collected from BARUNA JAYA IV in the Banda Sea, Ceram Sea or Seram Sea, Flores...

Geological Mapping of Sabah, Malaysia, Using Airborne Gravity Survey

DEFF Research Database (Denmark)

Fauzi Nordin, Ahmad; Jamil, Hassan; Noor Isa, Mohd

2016-01-01

Airborne gravimetry is an effective tool for mapping local gravity fields using a combination of airborne sensors, aircraft and positioning systems. It is suitable for gravity surveys over difficult terrains and areas mixed with land and ocean. This paper describes the geological mapping of Sabah...... using airborne gravity surveys. Airborne gravity data over land areas of Sabah has been combined with the marine airborne gravity data to provide a seamless land-to-sea gravity field coverage in order to produce the geological mapping. Free-air and Bouguer anomaly maps (density 2.67 g/cm3) have been...... derived from the airborne data both as simple ad-hoc plots (at aircraft altitude), and as final plots from the downward continued airborne data, processed as part of the geoids determination. Data are gridded at 0.025 degree spacing which is about 2.7 km and the data resolution of the filtered airborne...

Spectral Interpretation of Wave-vortex Duality in Northern South China Sea

Science.gov (United States)

Cao, H.; Jing, Z.; Yan, T.

2017-12-01

The mesoscale to submesocale oceanic dynamics are characterized by a joint effect of vortex and wave component, which primarily declares the partition between geostrophic balanced and unbalanced flows. The spectral method is a favorable approach that can afford the muti-scale analysis. This study investigates the characteristics of horizontal wavenumber spectra in Nothern South China Sea using orbital altimeter data (SARA/AltiKa), 13-yr shipboard ADCP (Acoustic Doppler Current Profiler) measurements (2014-2016), and a high-resolution numerical simulation (llc4320 Mitgcm). The observed SSH (sea surface height) spectrum presents a conspicuous transition at scales of 50-100 km, which clearly shows the inconsistency with geostrophic balance. The Helmholtz decomposition separating the wave and vortex energy for the spectra of ADCP and numerical model data shows that ageostrophic flows should be responsible for the spectral discrepancy with the QG (qusi-geostrophic) turbulence theory. Generally, it is found that inertia-gravity waves (including internal tides) govern the significant kinetic energy in the submesoscale range in Northern South China Sea. More specific analysis suggests that the wave kinetic energy can extend to a large scale of 500 km or more from the zonal velocity spectra at the left-center of Luzon Strait, which appears to be dominated by inertia-gravity waves likely emitted by the intrusion of the west pacific at Luzon Strait. Instead, the development of eddy kinetic energy at this place is strictly constrained by the width of the strait.

Alaska Phocid Argos Telemetry Archive (2004-2013)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Polar Ecosystems Program conducts research and monitoring on phocid seals in the East Bering Sea, West Bering Sea, Gulf of Alaska, Beaufort Sea, and Chukchi Sea...

Pacific walrus (Odobenus rosmarus divergens resource selection in the Northern Bering Sea.

Directory of Open Access Journals (Sweden)

Chadwick V Jay

Full Text Available The Pacific walrus is a large benthivore with an annual range extending across the continental shelves of the Bering and Chukchi Seas. We used a discrete choice model to estimate site selection by adult radio-tagged walruses relative to the availability of the caloric biomass of benthic infauna and sea ice concentration in a prominent walrus wintering area in the northern Bering Sea (St. Lawrence Island polynya in 2006, 2008, and 2009. At least 60% of the total caloric biomass of dominant macroinfauna in the study area was composed of members of the bivalve families Nuculidae, Tellinidae, and Nuculanidae. Model estimates indicated walrus site selection was related most strongly to tellinid bivalve caloric biomass distribution and that walruses selected lower ice concentrations from the mostly high ice concentrations that were available to them (quartiles: 76%, 93%, and 99%. Areas with high average predicted walrus site selection generally coincided with areas of high organic carbon input identified in other studies. Projected decreases in sea ice in the St. Lawrence Island polynya and the potential for a concomitant decline of bivalves in the region could result in a northward shift in the wintering grounds of walruses in the northern Bering Sea.

Global gravity field from recent satellites (DTU15) - Arctic improvements

DEFF Research Database (Denmark)

Andersen, O. B.; Knudsen, P.; Kenyon, S.

2017-01-01

Global marine gravity field modelling using satellite altimetry is currently undergoing huge improvement with the completion of the Jason-1 end-of-life geodetic mission, but particularly with the continuing Cryosat-2 mission. These new satellites provide three times as many geodetic mission...... altimetric sea surface height observations as ever before. The impact of these new geodetic mission data is a dramatic improvement of particularly the shorter wavelength of the gravity field (10-20 km) which is now being mapped at significantly higher accuracy. The quality of the altimetric gravity field...... is in many places surpassing the quality of gravity fields derived using non-commercial marine gravity observations. Cryosat-2 provides for the first time altimetry throughout the Arctic Ocean up to 88°N. Here, the huge improvement in marine gravity mapping is shown through comparison with high quality...

Gravity anomalies and associated tectonic features over the Indian Peninsular Shield and adjoining ocean basins

Science.gov (United States)

Mishra, D. C.; Arora, K.; Tiwari, V. M.

2004-02-01

A combined gravity map over the Indian Peninsular Shield (IPS) and adjoining oceans brings out well the inter-relationships between the older tectonic features of the continent and the adjoining younger oceanic features. The NW-SE, NE-SW and N-S Precambrian trends of the IPS are reflected in the structural trends of the Arabian Sea and the Bay of Bengal suggesting their probable reactivation. The Simple Bouguer anomaly map shows consistent increase in gravity value from the continent to the deep ocean basins, which is attributed to isostatic compensation due to variations in the crustal thickness. A crustal density model computed along a profile across this region suggests a thick crust of 35-40 km under the continent, which reduces to 22/20-24 km under the Bay of Bengal with thick sediments of 8-10 km underlain by crustal layers of density 2720 and 2900/2840 kg/m 3. Large crustal thickness and trends of the gravity anomalies may suggest a transitional crust in the Bay of Bengal up to 150-200 km from the east coast. The crustal thickness under the Laxmi ridge and east of it in the Arabian Sea is 20 and 14 km, respectively, with 5-6 km thick Tertiary and Mesozoic sediments separated by a thin layer of Deccan Trap. Crustal layers of densities 2750 and 2950 kg/m 3 underlie sediments. The crustal density model in this part of the Arabian Sea (east of Laxmi ridge) and the structural trends similar to the Indian Peninsular Shield suggest a continent-ocean transitional crust (COTC). The COTC may represent down dropped and submerged parts of the Indian crust evolved at the time of break-up along the west coast of India and passage of Reunion hotspot over India during late Cretaceous. The crustal model under this part also shows an underplated lower crust and a low density upper mantle, extending over the continent across the west coast of India, which appears to be related to the Deccan volcanism. The crustal thickness under the western Arabian Sea (west of the Laxmi ridge

Analysis of Alabama Airborne Gravity at Three Altitudes: Expected Accuracy and Spatial Resolution from a Future Tibetan Airborne Gravity Survey

Directory of Open Access Journals (Sweden)

Chi-Hsun Huang

2013-01-01

Full Text Available In situ airborne gravity data at altitudes of 11, 6.3, and 1.7 km over a smooth area of Alabama are used to assess gravity accuracy and errors in upward and downward continuations. Analysis of the Alabama free-air anomaly gravity data at crossover points at the three altitudes suggests 1 - 2 mgal accuracy for the dataset. Gravity data at each altitude are then expanded into local 3D Fourier series, to prepare for continuation. This Fourier representation results in continuation errors at few-mgal level in Alabama, even in the extreme case of downward continuation from 11 km to sea level. The result in Alabama inspires an airborne gravity survey over the rough, inaccessible terrain of Tibet. Similar investigations as in Alabama are made in Tibet using EGM08-derived airborne gravity data at flight altitudes of 10, 5, and 0 km. Bouguer anomalies at the 10-km altitude preserve the major tectonic features of Tibet. Downward continuation errors increase with terrain roughness, but the survey can enhance local tectonic features. This study highlights the value of a future Tibetan airborne gravity survey and points out the expected gravity accuracy and spatial resolution from this survey.

Raw Knudsen Chirp 320BR subbottom profiler - Knudsen subbottom profile data for the Chukchi Cap and Arctic Ocean.

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Knudsen Chirp 320BR subbottom profiler - Knudsen subbottom profile data were collected in Raw Knudsen SEG-Y Datagram format.

Stratospheric gravity wave activities inferred through the GPS radio occultation technique

International Nuclear Information System (INIS)

Wrasse, Cristiano Max; Takahashi, Hisao; Fechine, Joaquim; Denardini, Clezio Marcos; Wickert, Jens

2007-01-01

Stratospheric gravity wave activities were deduced from GPS radio occultation temperature profiles obtained by CHAMP satellite between 2001 and 2005. Potential energy profiles are used to analyze the gravity wave activity over South America. The results showed an inter-annual variation of the potential energy integrated between 24 and 34 km of altitude. The gravity wave activity is more concentrated around the equatorial region. In order to evaluate the seasonal variation of the gravity wave activity, a mean potential energy was determined over (10 deg N-10 deg S) and (100 deg W-20 deg W). The results showed a lower gravity wave activity during winter time, while during spring time the mean potential energy showed an increase in the wave activity. The results of the mean potential energy also showed that the gravity wave activity in the lower stratosphere exhibits a higher wave activity during 2002 and 2004 and a lower wave activity during 2003 and 2005. (author)

Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from JOHAN HJORT in the Barents Sea, North Greenland Sea and Norwegian Sea from 2000-05-27 to 2000-06-20 (NODC Accession 0115683)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0115683 includes biological, chemical, discrete sample, physical and profile data collected from JOHAN HJORT in the Barents Sea, North Greenland Sea...

How well does wind speed predict air-sea gas transfer in the sea ice zone? A synthesis of radon deficit profiles in the upper water column of the Arctic Ocean

Science.gov (United States)

Loose, B.; Kelly, R. P.; Bigdeli, A.; Williams, W.; Krishfield, R.; Rutgers van der Loeff, M.; Moran, S. B.

2017-05-01

We present 34 profiles of radon-deficit from the ice-ocean boundary layer of the Beaufort Sea. Including these 34, there are presently 58 published radon-deficit estimates of air-sea gas transfer velocity (k) in the Arctic Ocean; 52 of these estimates were derived from water covered by 10% sea ice or more. The average value of k collected since 2011 is 4.0 ± 1.2 m d-1. This exceeds the quadratic wind speed prediction of weighted kws = 2.85 m d-1 with mean-weighted wind speed of 6.4 m s-1. We show how ice cover changes the mixed-layer radon budget, and yields an "effective gas transfer velocity." We use these 58 estimates to statistically evaluate the suitability of a wind speed parameterization for k, when the ocean surface is ice covered. Whereas the six profiles taken from the open ocean indicate a statistically good fit to wind speed parameterizations, the same parameterizations could not reproduce k from the sea ice zone. We conclude that techniques for estimating k in the open ocean cannot be similarly applied to determine k in the presence of sea ice. The magnitude of k through gaps in the ice may reach high values as ice cover increases, possibly as a result of focused turbulence dissipation at openings in the free surface. These 58 profiles are presently the most complete set of estimates of k across seasons and variable ice cover; as dissolved tracer budgets they reflect air-sea gas exchange with no impact from air-ice gas exchange.

Analysis of tidal currents in the North Sea from shipboard acoustic Doppler current profiler data

Science.gov (United States)

Vindenes, Håvard; Orvik, Kjell Arild; Søiland, Henrik; Wehde, Henning

2018-06-01

North Sea tidal currents are determined by applying harmonic analysis to ship-borne acoustic Doppler current profiler data recorded from 1999 to 2016, covering large areas of the northern North Sea. Direct current measurement data sets of this magnitude are rare in the otherwise well investigated North Sea, and thus it is a valuable asset in studying and expanding our understanding of its tidal currents and circulation in general. The harmonic analysis is applied to a least squares fit of the current observations at a set of knot points. Results from the harmonic analysis compare favorably to tidal parameters estimated from observations from moored instruments. The analysis shows that the tides are characterized by strong semi-diurnal component, with amplitudes of the principal Lunar constituent ranging from 1.6 cm/s in the Skagerrak to 67 cm/s in the Fair Isle Channel. Diurnal tides are found to be approximately one fifth the strength of the predominant semi-diurnal constituent. Output from a regional barotropic tide model compares well to tidal current determined from the harmonic analysis of the Acoustic Doppler Current Profiler data.

Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the JOHAN HJORT in the Barents Sea, North Greenland Sea and Norwegian Sea from 1999-06-15 to 1999-07-07 (NODC Accession 0115678)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115678 includes chemical, discrete sample, physical and profile data collected from JOHAN HJORT in the Barents Sea, North Greenland Sea and Norwegian...

The gravity field and crustal structure of the northwestern Arabian Platform in Jordan

Science.gov (United States)

Batayneh, A. T.; Al-Zoubi, A. S.

2001-01-01

The Bouguer gravity field over the northwestern Arabian Platform in Jordan is dominated by large variations, ranging from -132 to +4 mGal. A study of the Bouguer anomaly map shows that the gravity field maintains a general north-northeasterly trend in the Wadi Araba-Dead Sea-Jordan Riff, Northern Highlands and Northeast Jordanian Limestone Area, while the remainder of the area shows north-northwesterly-trending gravity anomalies. Results of 2-D gravity modeling of the Bouguer gravity field indicate that the crustal thickness in Jordan is ˜ 38 km, which is similar to crustal thicknesses obtained from refraction data in northern Jordan and Saudi Arabia, and from gravity data in Syria.

Lectures on 2D gravity and 2D string theory

International Nuclear Information System (INIS)

Ginsparg, P.; Moore, G.

1992-01-01

This report the following topics: loops and states in conformal field theory; brief review of the Liouville theory; 2D Euclidean quantum gravity I: path integral approach; 2D Euclidean quantum gravity II: canonical approach; states in 2D string theory; matrix model technology I: method of orthogonal polynomials; matrix model technology II: loops on the lattice; matrix model technology III: free fermions from the lattice; loops and states in matrix model quantum gravity; loops and states in the C=1 matrix model; 6V model fermi sea dynamics and collective field theory; and string scattering in two spacetime dimensions

Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from BARUNA JAYA I in the Bali Sea, Banda Sea and others from 1994-01-28 to 1994-02-25 (NCEI Accession 0144624)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0144624 includes discrete sample and profile data collected from BARUNA JAYA I in the Bali Sea, Banda Sea, Celebes Sea, Ceram Sea or Seram Sea, Flores...

Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from BARUNA JAYA I in the Bali Sea, Banda Sea and others from 1993-08-08 to 1993-09-09 (NCEI Accession 0144623)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0144623 includes discrete sample and profile data collected from BARUNA JAYA I in the Bali Sea, Banda Sea, Celebes Sea, Ceram Sea or Seram Sea, Flores...

Arctic sea ice a major determinant in Mandt's black guillemot movement and distribution during non-breeding season

Science.gov (United States)

Divoky, G.J.; Douglas, David C.; Stenhouse, I. J.

2016-01-01

Mandt's black guillemot (Cepphus grylle mandtii) is one of the few seabirds associated in all seasons with Arctic sea ice, a habitat that is changing rapidly. Recent decreases in summer ice have reduced breeding success and colony size of this species in Arctic Alaska. Little is known about the species' movements and distribution during the nine month non-breeding period (September–May), when changes in sea ice extent and composition are also occurring and predicted to continue. To examine bird movements and the seasonal role of sea ice to non-breeding Mandt's black guillemots, we deployed and recovered (n = 45) geolocators on individuals at a breeding colony in Arctic Alaska during 2011–2015. Black guillemots moved north to the marginal ice zone (MIZ) in the Beaufort and Chukchi seas immediately after breeding, moved south to the Bering Sea during freeze-up in December, and wintered in the Bering Sea January–April. Most birds occupied the MIZ in regions averaging 30–60% sea ice concentration, with little seasonal variation. Birds regularly roosted on ice in all seasons averaging 5 h d−1, primarily at night. By using the MIZ, with its roosting opportunities and associated prey, black guillemots can remain in the Arctic during winter when littoral waters are completely covered by ice.

Crustal structure and development of the SW Barents Sea and the adjacent continental margin

Energy Technology Data Exchange (ETDEWEB)

Breivik, Asbjoern Johan

1998-12-31

Because of its expected petroleum potential, the western Barents Sea has been extensively mapped and investigated. The present thesis deals with many aspects of the geological development of this area. The emphasis is on Late Paleozoic structuring, Late Mesozoic basin formation, and early Tertiary margin formation including geodynamical response to the late Cenozoic sedimentation. The thesis begins with a review of the literature on the Late Palaeozoic structural development of the south-western Barents Sea, Svalbard and eastern Greenland. A structural map is developed for the Upper Carboniferous rift system in the southwestern Barents Sea that shows the interference of the northeasterly and the northerly structural grain. A discussion of the Ottar Basin uses a combination of seismic interpretation and gravity modelling to investigate this important structural element of the Upper Palaeozoic rift system. Previous work on Late Mesozoic basin formation in the southwestern Barents Sea is extended by incorporating new seismic reflection data and gravity modelling. Finally, the focus is shifted from the Barents Sea shelf to the continental-ocean transition and the oceanic basin. Gridded free-air gravity data from the ERS-1 enables the construction of a Bouguer gravity map of unprecedented resolution. The relationship between isostacy and gravity was resolved by modelling the thermal structure across the margin. Admittance analysis of the relationship between bathymetry and free-air gravity indicates an elastic thickness of the oceanic Lithosphere of 15-20 km, which is compatible with the depth to the 450{sup o}C isotherm obtained from thermal modelling. It is concluded that the southwestern Barents Sea margin does not deviate in any significant respects from passive rifted margins, except for a very straight and narrow continent-ocean transition zone. 332 refs., 55 figs., 7 tabs.

Normalization to specific gravity prior to analysis improves information recovery from high resolution mass spectrometry metabolomic profiles of human urine.

Science.gov (United States)

Edmands, William M B; Ferrari, Pietro; Scalbert, Augustin

2014-11-04

Extraction of meaningful biological information from urinary metabolomic profiles obtained by liquid-chromatography coupled to mass spectrometry (MS) necessitates the control of unwanted sources of variability associated with large differences in urine sample concentrations. Different methods of normalization either before analysis (preacquisition normalization) through dilution of urine samples to the lowest specific gravity measured by refractometry, or after analysis (postacquisition normalization) to urine volume, specific gravity and median fold change are compared for their capacity to recover lead metabolites for a potential future use as dietary biomarkers. Twenty-four urine samples of 19 subjects from the European Prospective Investigation into Cancer and nutrition (EPIC) cohort were selected based on their high and low/nonconsumption of six polyphenol-rich foods as assessed with a 24 h dietary recall. MS features selected on the basis of minimum discriminant selection criteria were related to each dietary item by means of orthogonal partial least-squares discriminant analysis models. Normalization methods ranked in the following decreasing order when comparing the number of total discriminant MS features recovered to that obtained in the absence of normalization: preacquisition normalization to specific gravity (4.2-fold), postacquisition normalization to specific gravity (2.3-fold), postacquisition median fold change normalization (1.8-fold increase), postacquisition normalization to urinary volume (0.79-fold). A preventative preacquisition normalization based on urine specific gravity was found to be superior to all curative postacquisition normalization methods tested for discovery of MS features discriminant of dietary intake in these urinary metabolomic datasets.

Rift systems of the Russian Eastern Arctic shelf and Arctic deep water basins: link between geological history and geodynamics

Directory of Open Access Journals (Sweden)

A. M. Nikishin

2017-01-01

Full Text Available In our study, we have developed a new tectonic scheme of the Arctic Ocean, which is based mainly on seismic profiles obtained in the Arctic-2011, Arctic-2012 and Arctic-2014 Projects implemented in Russia. Having interpreted many seismic profiles, we propose a new seismic stratigraphy of the Arctic Ocean. Our main conclusions are drawn from the interpretation of the seismic profiles and the analysis of the regional geological data. The results of our study show that rift systems within the Laptev, the East Siberian and the Chukchi Seas were formed not earlier than Aptian. The geological structure of the Eurasian, Podvodnikov, Toll and Makarov Basins is described in this paper. Having synthesized all the available data on the study area, we propose the following model of the geological history of the Arctic Ocean: 1. The Canada Basin formed till the Aptian (probably, during Hauterivian-Barremian time. 2. During the Aptian-Albian, large-scale tectonic and magmatic events took place, including plume magmatism in the area of the De Long Islands, Mendeleev Ridge and other regions. Continental rifting started after the completion of the Verkhoyansk-Chukotka orogenу, and rifting occurred on the shelf of the Laptev, East Siberian, North Chukchi and South Chukchi basins, and the Chukchi Plateau; simultaneously, continental rifting started in the Podvodnikov and Toll basins. 3. Perhaps the Late Cretaceous rifting continued in the Podvodnikov and Toll basins. 4. At the end of the Late Cretaceous and Paleocene, the Makarov basin was formed by rifting, although local spreading of oceanic crust during its formation cannot be excluded. 5. The Eurasian Basin started to open in the Early Eocene. We, of course, accept that our model of the geological history of the Arctic Ocean, being preliminary and debatable, may need further refining. In this paper, we have shown a link between the continental rift systems on the shelf and the formation history of the Arctic

Definition of an ISO 19115 metadata profile for SeaDataNet II Cruise Summary Reports and its XML encoding

Science.gov (United States)

Boldrini, Enrico; Schaap, Dick M. A.; Nativi, Stefano

2013-04-01

SeaDataNet implements a distributed pan-European infrastructure for Ocean and Marine Data Management whose nodes are maintained by 40 national oceanographic and marine data centers from 35 countries riparian to all European seas. A unique portal makes possible distributed discovery, visualization and access of the available sea data across all the member nodes. Geographic metadata play an important role in such an infrastructure, enabling an efficient documentation and discovery of the resources of interest. In particular: - Common Data Index (CDI) metadata describe the sea datasets, including identification information (e.g. product title, interested area), evaluation information (e.g. data resolution, constraints) and distribution information (e.g. download endpoint, download protocol); - Cruise Summary Reports (CSR) metadata describe cruises and field experiments at sea, including identification information (e.g. cruise title, name of the ship), acquisition information (e.g. utilized instruments, number of samples taken) In the context of the second phase of SeaDataNet (SeaDataNet 2 EU FP7 project, grant agreement 283607, started on October 1st, 2011 for a duration of 4 years) a major target is the setting, adoption and promotion of common international standards, to the benefit of outreach and interoperability with the international initiatives and communities (e.g. OGC, INSPIRE, GEOSS, …). A standardization effort conducted by CNR with the support of MARIS, IFREMER, STFC, BODC and ENEA has led to the creation of a ISO 19115 metadata profile of CDI and its XML encoding based on ISO 19139. The CDI profile is now in its stable version and it's being implemented and adopted by the SeaDataNet community tools and software. The effort has then continued to produce an ISO based metadata model and its XML encoding also for CSR. The metadata elements included in the CSR profile belong to different models: - ISO 19115: E.g. cruise identification information, including

Using voids to unscreen modified gravity

Science.gov (United States)

Falck, Bridget; Koyama, Kazuya; Zhao, Gong-Bo; Cautun, Marius

2018-04-01

The Vainshtein mechanism, present in many models of gravity, is very effective at screening dark matter haloes such that the fifth force is negligible and general relativity is recovered within their Vainshtein radii. Vainshtein screening is independent of halo mass and environment, in contrast to e.g. chameleon screening, making it difficult to test. However, our previous studies have found that the dark matter particles in filaments, walls, and voids are not screened by the Vainshtein mechanism. We therefore investigate whether cosmic voids, identified as local density minima using a watershed technique, can be used to test models of gravity that exhibit Vainshtein screening. We measure density, velocity, and screening profiles of stacked voids in cosmological N-body simulations using both dark matter particles and dark matter haloes as tracers of the density field. We find that the voids are completely unscreened, and the tangential velocity and velocity dispersion profiles of stacked voids show a clear deviation from Λ cold dark matter at all radii. Voids have the potential to provide a powerful test of gravity on cosmological scales.

Atmospheric Profiles, Clouds and the Evolution of Sea Ice Cover in the Beaufort and Chukchi Seas

Science.gov (United States)

2014-09-30

developed by incorporating the proposed IR sensors and ground-sky temperature difference algorithm into a tethered balloon borne payload (Figure 3...into the cloud base. RESULTS FROM FY 2014 • A second flight of the tethered balloon -borne IR cloud margin sensor was conducted in Colorado on...Figure 3: Tethered balloon -borne IR sensing payload IR Cloud Margin Sensor Figure 4: First successful flight validation of the IR cloud

Application of Natural Radioisotopes as Tracers of Particulate Organic Carbon Transport, Export and Burial Processes in Chukchi Sea, Arctic Ocean

Energy Technology Data Exchange (ETDEWEB)

Wen, Yu; Jianhua, He [Key Lab of Global Change and Marine-Atmosphere Chemistry, State Oceanic Administration, Xiamen (China)

2013-07-15

To evaluate the efficiency of the biological pump and carbon sequestration content on the Arctic shelf, estimations of POC export fluxes derived from 234Th/238U disequilibrium and organic carbon burial rate from 210Pbex chronology in sediment core were made during the 3rd Chinese National Arctic Research Expedition (CHINARE-3), Jul 12-Sep 22, 2008. Great deficits of {sup 234}Th to {sup 238}U were observed widely over the Chukchi shelf, with an average {sup 234}Th/{sup 238}U of 0.64{+-}0.28, resulting from intense particle scavenging. The average POC export fluxes in the entire study area, shelf and slope area were 24.9 {+-} 23.3, 29.5 {+-} 23.0 and 2.1 {+-} 0.5 mmol C/m{sup 2}d, respectively, i.e. 21% of the primary production on average was exported to the benthos. An organic carbon burial rate of 517 mmol C/m{sup 2}a were estimated, accounting for 6% of the average primary production. The efficient biological pump led to 11.6{+-}9.0 T g C exported to benthos and 3.4 T g C buried permanently in the sediment per year, accounting for 0.3% of total POC export amount and 2.1% of total organic carbon burial amount of the global ocean. (author)

An improved model for the Earth's gravity field

Science.gov (United States)

Tapley, B. D.; Shum, C. K.; Yuan, D. N.; Ries, J. C.; Schutz, B. E.

1989-01-01

An improved model for the Earth's gravity field, TEG-1, was determined using data sets from fourteen satellites, spanning the inclination ranges from 15 to 115 deg, and global surface gravity anomaly data. The satellite measurements include laser ranging data, Doppler range-rate data, and satellite-to-ocean radar altimeter data measurements, which include the direct height measurement and the differenced measurements at ground track crossings (crossover measurements). Also determined was another gravity field model, TEG-1S, which included all the data sets in TEG-1 with the exception of direct altimeter data. The effort has included an intense scrutiny of the gravity field solution methodology. The estimated parameters included geopotential coefficients complete to degree and order 50 with selected higher order coefficients, ocean and solid Earth tide parameters, Doppler tracking station coordinates and the quasi-stationary sea surface topography. Extensive error analysis and calibration of the formal covariance matrix indicate that the gravity field model is a significant improvement over previous models and can be used for general applications in geodesy.

The major tectonic boundaries of the Northern Red Sea rift, Egypt derived from geophysical data analysis

Science.gov (United States)

Saleh, Salah; Pamukçu, Oya; Brimich, Ladislav

2017-09-01

(with limited heat flow values) below this region. Additionally in this study, the crustal thinning was investigated with heat flow, magnetic and free air gravity anomalies in the Northern Red Sea rift region. In fact, the crustal thinning of the study area was also proportional to the regions of observable high heat flow values. Finally, our results were found to be well correlated with the topography, free air, aeromagnetic and heat flow dataset profiles crossing most of the study area.

Organohalogen pollutants in herring from the northern Baltic Sea: Concentrations, congener profiles and explanatory factors

International Nuclear Information System (INIS)

Koistinen, Jaana; Kiviranta, Hannu; Ruokojaervi, Paeivi; Parmanne, Raimo; Verta, Matti; Hallikainen, Anja; Vartiainen, Terttu

2008-01-01

Organohalogen contaminants were investigated in Baltic herring caught from three catchment areas in the Baltic Sea, off the coasts of Finland. Pools of both small and large herring were analysed for polychlorinated biphenyls (PCB), dibenzo-p-dioxins, dibenzofurans, naphthalenes, camphenes (toxaphene), polybrominated diphenyl ethers and the pesticide DDT and its metabolites. PCB concentrations per fresh weight in small herring were at the same level in all catchment areas, i.e. the Bothnian Bay, the Bothnian Sea and the Gulf of Finland, revealing no hot spots and reflecting most likely long term emissions and atmospheric deposition. Differences in the levels and/or congener profiles of other contaminants between catchment areas may be explained by point sources. Similar concentrations in small and large herring in the Gulf of Finland were possibly due to their common nutrition. In the other areas, differences between small and large herring most likely reflected their different food sources. - Sources of pollutants are reflected in levels and congener profiles of pollutants in Baltic herring

Temperature and salinity profile data collected by bottle on multiple cruises in the Baltic Sea, Baffin Bay, Davis Strait, the North Atlantic Ocean, and the North Sea from 02 January 1985 to 13 November 1989 (NODC Accession 0000056)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and nutrients data were collected using bottle casts from DANA and other platforms in Baffin Sea, Baltic Sea, Davis Strait, North Sea, and North...

Bioactive Potential of Marine Macroalgae from the Central Red Sea (Saudi Arabia) Assessed by High-Throughput Imaging-Based Phenotypic Profiling

KAUST Repository

Kremb, Stephan Georg; Mü ller, Constanze; Schmitt-Kopplin, Philippe; Voolstra, Christian R.

2017-01-01

Marine algae represent an important source of novel natural products. While their bioactive potential has been studied to some extent, limited information is available on marine algae from the Red Sea. This study aimed at the broad discovery of new bioactivities from a collection of twelve macroalgal species from the Central Red Sea. We used imaging-based High-Content Screening (HCS) with a diverse spectrum of cellular markers for detailed cytological profiling of fractionated algal extracts. The cytological profiles for 3 out of 60 algal fractions clustered closely to reference inhibitors and showed strong inhibitory activities on the HIV-1 reverse transcriptase in a single-enzyme biochemical assay, validating the suggested biological target. Subsequent chemical profiling of the active fractions of two brown algal species by ultra-high resolution mass spectrometry (FT-ICR-MS) revealed possible candidate molecules. A database query of these molecules led us to groups of compounds with structural similarities, which are suggested to be responsible for the observed activity. Our work demonstrates the versatility and power of cytological profiling for the bioprospecting of unknown biological resources and highlights Red Sea algae as a source of bioactives that may serve as a starting point for further studies.

Bioactive Potential of Marine Macroalgae from the Central Red Sea (Saudi Arabia) Assessed by High-Throughput Imaging-Based Phenotypic Profiling

KAUST Repository

Kremb, Stephan Georg

2017-03-20

Marine algae represent an important source of novel natural products. While their bioactive potential has been studied to some extent, limited information is available on marine algae from the Red Sea. This study aimed at the broad discovery of new bioactivities from a collection of twelve macroalgal species from the Central Red Sea. We used imaging-based High-Content Screening (HCS) with a diverse spectrum of cellular markers for detailed cytological profiling of fractionated algal extracts. The cytological profiles for 3 out of 60 algal fractions clustered closely to reference inhibitors and showed strong inhibitory activities on the HIV-1 reverse transcriptase in a single-enzyme biochemical assay, validating the suggested biological target. Subsequent chemical profiling of the active fractions of two brown algal species by ultra-high resolution mass spectrometry (FT-ICR-MS) revealed possible candidate molecules. A database query of these molecules led us to groups of compounds with structural similarities, which are suggested to be responsible for the observed activity. Our work demonstrates the versatility and power of cytological profiling for the bioprospecting of unknown biological resources and highlights Red Sea algae as a source of bioactives that may serve as a starting point for further studies.

Arctic and Antarctic Sea Ice Changes and Impacts (Invited)

Science.gov (United States)

Nghiem, S. V.

2013-12-01

The extent of springtime Arctic perennial sea ice, important to preconditioning summer melt and to polar sunrise photochemistry, continues its precipitous reduction in the last decade marked by a record low in 2012, as the Bromine, Ozone, and Mercury Experiment (BROMEX) was conducted around Barrow, Alaska, to investigate impacts of sea ice reduction on photochemical processes, transport, and distribution in the polar environment. In spring 2013, there was further loss of perennial sea ice, as it was not observed in the ocean region adjacent to the Alaskan north coast, where there was a stretch of perennial sea ice in 2012 in the Beaufort Sea and Chukchi Sea. In contrast to the rapid and extensive loss of sea ice in the Arctic, Antarctic sea ice has a trend of a slight increase in the past three decades. Given the significant variability in time and in space together with uncertainties in satellite observations, the increasing trend of Antarctic sea ice may arguably be considered as having a low confidence level; however, there was no overall reduction of Antarctic sea ice extent anywhere close to the decreasing rate of Arctic sea ice. There exist publications presenting various factors driving changes in Arctic and Antarctic sea ice. After a short review of these published factors, new observations and atmospheric, oceanic, hydrological, and geological mechanisms contributed to different behaviors of sea ice changes in the Arctic and Antarctic are presented. The contribution from of hydrologic factors may provide a linkage to and enhance thermal impacts from lower latitudes. While geological factors may affect the sensitivity of sea ice response to climate change, these factors can serve as the long-term memory in the system that should be exploited to improve future projections or predictions of sea ice changes. Furthermore, similarities and differences in chemical impacts of Arctic and Antarctic sea ice changes are discussed. Understanding sea ice changes and

Toward Joint Inversion of Gravity and Dyanamics

Science.gov (United States)

Jacoby, W. R.

To better understand geodynamic processes as seafloor spreading, plumes, subduction, and isostatic adjustment, gravity is inverted with "a prioriinformation from topography/bathymetry, seismic structure and dynamic models. Examples are subduction of the Juan de Fuca plate below Vancouver Island, the passive Black Sea­Turkey margin and Iceland ridge-plume interaction. Gravity and other data are averaged 50 km wide strips. Mass balances are estimated (showing also that the free air anomaly is misleading for narrow structures). The mass balances represent plate forces and plate bending, affecting the gravity signals and the isostatic state of continental margins and ridge-plume effects, which are highly correlated in space and cannot be separated without a priori information from modelling. The examples from widely different tectonic situations demonstrate that the art of regional-scale gravity inversion requires extensive background knowledge and inclusion of dynamic processes. It is difficult to conceive any formal, globally applicable procedure taking care of this; it is even a question, what is data, what a priori information? They are not distinguishable if all are included as foreward routines. The "accuracy" of models cannot be perfectly determined, if the "real" mass distribution is not known ­ if known, gravity inversion would be unnecessary. In reality only guesses are possible on the basis of observations and physical laws governing geodynamics. A priori information and gravity data limit the resolution of gravity inversion. Different model types are indistinguishable because adjustments within their parameter uncertainties permit a good fit. But gravity excludes wrong models (Karl Popper: science evolves by falsification of wrong models), and precise gravity guides and defines aims, targets and strategies for new observations.

Long-distance swimming by polar bears (Ursus maritimus) of the southern Beaufort Sea during years of extensive open water

Science.gov (United States)

2014-01-01

Polar bears (Ursus maritimus Phipps, 1774) depend on sea ice for catching marine mammal prey. Recent sea-ice declines have been linked to reductions in body condition, survival, and population size. Reduced foraging opportunity is hypothesized to be the primary cause of sea-ice-linked declines, but the costs of travel through a deteriorated sea-ice environment also may be a factor. We used movement data from 52 adult female polar bears wearing Global Positioning System (GPS) collars, including some with dependent young, to document long-distance swimming (>50 km) by polar bears in the southern Beaufort and Chukchi seas. During 6 years (2004-2009), we identified 50 long-distance swims by 20 bears. Swim duration and distance ranged from 0.7 to 9.7 days (mean = 3.4 days) and 53.7 to 687.1 km (mean = 154.2 km), respectively. Frequency of swimming appeared to increase over the course of the study. We show that adult female polar bears and their cubs are capable of swimming long distances during periods when extensive areas of open water are present. However, long-distance swimming appears to have higher energetic demands than moving over sea ice. Our observations suggest long-distance swimming is a behavioral response to declining summer sea-ice conditions.

Multiyear ice transport and small scale sea ice deformation near the Alaska coast measured by air-deployable Ice Trackers

Science.gov (United States)

Mahoney, A. R.; Kasper, J.; Winsor, P.

2015-12-01

Highly complex patterns of ice motion and deformation were captured by fifteen satellite-telemetered GPS buoys (known as Ice Trackers) deployed near Barrow, Alaska, in spring 2015. Two pentagonal clusters of buoys were deployed on pack ice by helicopter in the Beaufort Sea between 20 and 80 km offshore. During deployment, ice motion in the study region was effectively zero, but two days later the buoys captured a rapid transport event in which multiyear ice from the Beaufort Sea was flushed into the Chukchi Sea. During this event, westward ice motion began in the Chukchi Sea and propagated eastward. This created new openings in the ice and led to rapid elongation of the clusters as the westernmost buoys accelerated away from their neighbors to the east. The buoys tracked ice velocities of over 1.5 ms-1, with fastest motion occurring closest to the coast indicating strong current shear. Three days later, ice motion reversed and the two clusters became intermingled, rendering divergence calculations based on the area enclosed by clusters invalid. The data show no detectable difference in velocity between first year and multiyear ice floes, but Lagrangian timeseries of SAR imagery centered on each buoy show that first year ice underwent significant small-scale deformation during the event. The five remaining buoys were deployed by local residents on prominent ridges embedded in the landfast ice within 16 km of Barrow in order to track the fate of such features after they detached from the coast. Break-up of the landfast ice took place over a period of several days and, although the buoys each initially followed a similar eastward trajectory around Point Barrow into the Beaufort Sea, they rapidly dispersed over an area more than 50 km across. With rapid environmental and socio-economic change in the Arctic, understanding the complexity of nearshore ice motion is increasingly important for predict future changes in the ice and the tracking ice-related hazards

From the chlorophyll a in the surface layer to its vertical profile: a Greenland Sea relationship for satellite applications

Directory of Open Access Journals (Sweden)

A. Cherkasheva

2013-04-01

Full Text Available Current estimates of global marine primary production range over a factor of two. Improving these estimates requires an accurate knowledge of the chlorophyll vertical profiles, since they are the basis for most primary production models. At high latitudes, the uncertainty in primary production estimates is larger than globally, because here phytoplankton absorption shows specific characteristics due to the low-light adaptation, and in situ data and ocean colour observations are scarce. To date, studies describing the typical chlorophyll profile based on the chlorophyll in the surface layer have not included the Arctic region, or, if it was included, the dependence of the profile shape on surface concentration was neglected. The goal of our study was to derive and describe the typical Greenland Sea chlorophyll profiles, categorized according to the chlorophyll concentration in the surface layer and further monthly resolved profiles. The Greenland Sea was chosen because it is known to be one of the most productive regions of the Arctic and is among the regions in the Arctic where most chlorophyll field data are available. Our database contained 1199 chlorophyll profiles from R/Vs Polarstern and Maria S. Merian cruises combined with data from the ARCSS-PP database (Arctic primary production in situ database for the years 1957–2010. The profiles were categorized according to their mean concentration in the surface layer, and then monthly median profiles within each category were calculated. The category with the surface layer chlorophyll (CHL exceeding 0.7 mg C m−3 showed values gradually decreasing from April to August. A similar seasonal pattern was observed when monthly profiles were averaged over all the surface CHL concentrations. The maxima of all chlorophyll profiles moved from the greater depths to the surface from spring to late summer respectively. The profiles with the smallest surface values always showed a subsurface chlorophyll

Revisiting the contemporary sea-level budget on global and regional scales.

Science.gov (United States)

Rietbroek, Roelof; Brunnabend, Sandra-Esther; Kusche, Jürgen; Schröter, Jens; Dahle, Christoph

2016-02-09

Dividing the sea-level budget into contributions from ice sheets and glaciers, the water cycle, steric expansion, and crustal movement is challenging, especially on regional scales. Here, Gravity Recovery And Climate Experiment (GRACE) gravity observations and sea-level anomalies from altimetry are used in a joint inversion, ensuring a consistent decomposition of the global and regional sea-level rise budget. Over the years 2002-2014, we find a global mean steric trend of 1.38 ± 0.16 mm/y, compared with a total trend of 2.74 ± 0.58 mm/y. This is significantly larger than steric trends derived from in situ temperature/salinity profiles and models which range from 0.66 ± 0.2 to 0.94 ± 0.1 mm/y. Mass contributions from ice sheets and glaciers (1.37 ± 0.09 mm/y, accelerating with 0.03 ± 0.02 mm/y(2)) are offset by a negative hydrological component (-0.29 ± 0.26 mm/y). The combined mass rate (1.08 ± 0.3 mm/y) is smaller than previous GRACE estimates (up to 2 mm/y), but it is consistent with the sum of individual contributions (ice sheets, glaciers, and hydrology) found in literature. The altimetric sea-level budget is closed by coestimating a remaining component of 0.22 ± 0.26 mm/y. Well above average sea-level rise is found regionally near the Philippines (14.7 ± 4.39 mm/y) and Indonesia (8.3 ± 4.7 mm/y) which is dominated by steric components (11.2 ± 3.58 mm/y and 6.4 ± 3.18 mm/y, respectively). In contrast, in the central and Eastern part of the Pacific, negative steric trends (down to -2.8 ± 1.53 mm/y) are detected. Significant regional components are found, up to 5.3 ± 2.6 mm/y in the northwest Atlantic, which are likely due to ocean bottom pressure variations.

Stability of Fluvial and Gravity-flow Antidunes

Science.gov (United States)

Fedele, J. J.; Hoyal, D. C. J. D.; Demko, T. M.

2017-12-01

Antidunes develop as a consequence of interface (free surface) deformation and sediment transport feedback in supercritical flows. Fluvial (open-channel flow) antidunes have been studied extensively in the laboratory and the field, and recognized in ancient sedimentary deposits. Experiments on gravity flow (turbidity and density currents) antidunes indicate that they are more stable and long-lived than their fluvial counterpart but the mechanism controlling this stability is poorly understood. Sea floor bathymetric and subsurface data suggest that large-scale, antidune-like sediment waves are extremely common in deep-water, found in a wide range of settings and sediment characteristics. While most of these large features have been interpreted as cyclic steps, the term has been most likely overused due to the lack of recognition criteria and basic understanding on the differences between antidunes and cyclic steps formed under gravity flows. In principle, cyclic steps should be more common in confined or channel-lobe transition settings where flows tend to be more energetic or focused, while antidunes should prevail in regions of less confinement, under sheet-like or expanding flows. Using published, fluvial stable-antidune data, we show that the simplified 1D, mechanical-energy based analysis of flow over a localized fixed obstacle (Long, 1954; Baines, 1995; Kubo and Yokokawa, 2001) is inaccurate for representing flow over antidunes and their stability. Instead, a more detailed analysis of a flow along a long-wavelength (in relation to flow thickness) wavy bed that also considers the interactions between flow and sediment transport is used to infer conditions of antidune stability and the breaking of surface waves. In particular, the position of the surface wave crest in relation to the bedform crest, along with the role of average flow velocity, surface velocity, and surface wave celerity appear relevant in determining antidune instability. The analysis is

Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the HAKON MOSBY in the Barents Sea, North Greenland Sea and Norwegian Sea from 1999-10-03 to 1999-10-11 (NODC Accession 0113888)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113888 includes chemical, discrete sample, physical and profile data collected from HAKON MOSBY in the Barents Sea, North Greenland Sea and Norwegian...

Implications of fractured Arctic perennial ice cover on thermodynamic and dynamic sea ice processes

Science.gov (United States)

Asplin, Matthew G.; Scharien, Randall; Else, Brent; Howell, Stephen; Barber, David G.; Papakyriakou, Tim; Prinsenberg, Simon

2014-04-01

Decline of the Arctic summer minimum sea ice extent is characterized by large expanses of open water in the Siberian, Laptev, Chukchi, and Beaufort Seas, and introduces large fetch distances in the Arctic Ocean. Long waves can propagate deep into the pack ice, thereby causing flexural swell and failure of the sea ice. This process shifts the floe size diameter distribution smaller, increases floe surface area, and thereby affects sea ice dynamic and thermodynamic processes. The results of Radarsat-2 imagery analysis show that a flexural fracture event which occurred in the Beaufort Sea region on 6 September 2009 affected ˜40,000 km2. Open water fractional area in the area affected initially decreased from 3.7% to 2.7%, but later increased to ˜20% following wind-forced divergence of the ice pack. Energy available for lateral melting was assessed by estimating the change in energy entrainment from longwave and shortwave radiation in the mixed-layer of the ocean following flexural fracture. 11.54 MJ m-2 of additional energy for lateral melting of ice floes was identified in affected areas. The impact of this process in future Arctic sea ice melt seasons was assessed using estimations of earlier occurrences of fracture during the melt season, and is discussed in context with ocean heat fluxes, atmospheric mixing of the ocean mixed layer, and declining sea ice cover. We conclude that this process is an important positive feedback to Arctic sea ice loss, and timing of initiation is critical in how it affects sea ice thermodynamic and dynamic processes.

Geodetic and geophysical results from a Taiwan airborne gravity survey: Data reduction and accuracy assessment

DEFF Research Database (Denmark)

Hwang, C.W.; Hsiao, Y.S.; Shih, H.C.

2007-01-01

[ 1] An airborne gravity survey was conducted over Taiwan using a LaCoste and Romberg (LCR) System II air-sea gravimeter with gravity and global positioning system (GPS) data sampled at 1 Hz. The aircraft trajectories were determined using a GPS network kinematic adjustment relative to eight GPS ...... using airborne and surface gravity data and the other using surface data only, and the former yields a better agreement with the GPS-derived geoidal heights. Bouguer anomalies derived from airborne gravity by a rigorous numerical integration reveal important tectonic features....

On the use of airborne gravimetry in gravity field modelling: Experiences from the AGMASCO project

DEFF Research Database (Denmark)

Bastos, L.; Cunha, S.; Forsberg, René

2000-01-01

of the vertical accelerations acting on the airborne platform from the natural gravity signal. With the advances in DGPS techniques new prospects arise for gravity field recovery which are of great importance for geodesy, geophysics oceanography and satellite navigation. Furthermore, airborne gravimetric...... and the methods validated. Recovery of the gravity values directly from measurements with the Lacoste & Romberg air/sea gravimeter and from measurements with the inertial sensors was analysed. The potential of these sensors to recover gravity and the experience gained within this project are reported here....

Impact Of GOCE On The Nordic Gravity Field Modelling

DEFF Research Database (Denmark)

Yidiz, Hasan; Forsberg, René; Tscherning, C. C.

2011-01-01

GOCE level-2 Tzz and Txx gravity gradients at satellite altitude are used in combination as input data to predict surface free air gravity anomalies over the Nordic region using Least Square Collocation. We test the performance of using covariance functions created separately from Tzz gradients a...... Surface model, both the NKG-2004 quasi-geoid model of the Nordic and Baltic Area and the one obtained using second generation GOCE spherical harmonic coefficients based on time-wise method can successfully reproduce the higher level of the Baltic Sea relative to the Atlantic Ocean....

An Assessment of State-of-the-Art Mean Sea Surface and Geoid Models of the Arctic Ocean: Implications for Sea Ice Freeboard Retrieval

Science.gov (United States)

Skourup, Henriette; Farrell, Sinéad Louise; Hendricks, Stefan; Ricker, Robert; Armitage, Thomas W. K.; Ridout, Andy; Andersen, Ole Baltazar; Haas, Christian; Baker, Steven

2017-11-01

State-of-the-art Arctic Ocean mean sea surface (MSS) models and global geoid models (GGMs) are used to support sea ice freeboard estimation from satellite altimeters, as well as in oceanographic studies such as mapping sea level anomalies and mean dynamic ocean topography. However, errors in a given model in the high-frequency domain, primarily due to unresolved gravity features, can result in errors in the estimated along-track freeboard. These errors are exacerbated in areas with a sparse lead distribution in consolidated ice pack conditions. Additionally model errors can impact ocean geostrophic currents, derived from satellite altimeter data, while remaining biases in these models may impact longer-term, multisensor oceanographic time series of sea level change in the Arctic. This study focuses on an assessment of five state-of-the-art Arctic MSS models (UCL13/04 and DTU15/13/10) and a commonly used GGM (EGM2008). We describe errors due to unresolved gravity features, intersatellite biases, and remaining satellite orbit errors, and their impact on the derivation of sea ice freeboard. The latest MSS models, incorporating CryoSat-2 sea surface height measurements, show improved definition of gravity features, such as the Gakkel Ridge. The standard deviation between models ranges 0.03-0.25 m. The impact of remaining MSS/GGM errors on freeboard retrieval can reach several decimeters in parts of the Arctic. While the maximum observed freeboard difference found in the central Arctic was 0.59 m (UCL13 MSS minus EGM2008 GGM), the standard deviation in freeboard differences is 0.03-0.06 m.

Temperature profiles collected by Commonwealth Scientific Industrial Research Organization (CSIRO) from Fish Tag data from the Coral Sea, Tasman Sea, and the Indian Oceans from 15 November 2008 to 26 July 2009 (NODC Accession 0067650)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profiles were collected from Fish Tag data from the biologging group at CSIRO, from the Coral Sea, Tasman Sea, and the Indian Oceans from 15 November...

Brief communication "Seismic and acoustic-gravity signals from the source of the 2004 Indian Ocean Tsunami"

Directory of Open Access Journals (Sweden)

A. Raveloson

2012-02-01

Full Text Available The great Sumatra-Andaman earthquake of 26 December 2004 caused seismic waves propagating through the solid Earth, tsunami waves propagating through the ocean and infrasound or acoustic-gravity waves propagating through the atmosphere. Since the infrasound wave travels faster than its associated tsunami, it is for warning purposes very intriguing to study the possibility of infrasound generation directly at the earthquake source. Garces et al. (2005 and Le Pichon et al. (2005 emphasized that infrasound was generated by mountainous islands near the epicenter and by tsunami propagation along the continental shelf to the Bay of Bengal. Mikumo et al. (2008 concluded from the analysis of travel times and amplitudes of first arriving acoustic-gravity waves with periods of about 400–700 s that these waves are caused by coseismic motion of the sea surface mainly to the west of the Nicobar islands in the open seas. We reanalyzed the acoustic-gravity waves and corrected the first arrival times of Mikumo et al. (2008 by up to 20 min. We found the source of the first arriving acoustic-gravity wave about 300 km to the north of the US Geological Survey earthquake epicenter. This confirms the result of Mikumo et al. (2008 that sea level changes at the earthquake source cause long period acoustic-gravity waves, which indicate that a tsunami was generated. Therefore, a denser local network of infrasound stations may be helpful for tsunami warnings, not only for very large earthquakes.

Penetrating Shortwave Radiation and Sea Ice Algae feedbacks using the Community Earth System Model

Science.gov (United States)

Arntsen, A. E.; Perovich, D. K.; Bailey, D. A.; Holland, M. M.

2017-12-01

Transmittance of solar radiation through the sea ice cover determines energy transfer to the upper ocean in the form of heat as well as photosynthetically active radiation (PAR) available for the growth of under ice phytoplankton and bottom ice algal communities. A thinning ice cover, increased pond coverage, and earlier melt onset has increased light availability to the upper ocean in contemporary Arctic ice-covered waters. To investigate seasonal and spatial variability of solar shortwave irradiance penetrating the ice cover in the Beaufort and Chukchi Sea regions, we use the fully coupled Community Earth System Model (CESM) in conjunction with a multistream radiative transfer model constrained and initiated by in situ observations. Results inform the importance of light attenuation by ice-based algal pigments within large scale global climate models. We demonstrate the presence of bio-optical feedbacks related to a younger ice cover and examine how these relationships are impacting the trajectory of under ice blooms and the energy budget of the ice-ocean system.

Temperature profile data collected using BT and XBT casts from NOAA Ship RESEARCHER and other platforms in the Bering Sea and other Sea areas from 1987-02-25 to 1987-07-27 (NODC Accession 8700280)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile data were collected using XBT and BT casts from NOAA Ship RESEARCHER and other platforms in the Bering Sea and other Sea areas from 25 February...

Comparative effects of dietary sea urchin shell powder and feed additives on meat quality and fatty acid profiles of broiler breast meat

Directory of Open Access Journals (Sweden)

Sam Churl Kim

2015-08-01

Full Text Available This study was a small pen trial in which we investigated comparative effects of dietary sea urchin shell powder and feed additives on meat quality and fatty acid profiles of broiler breast meat. A total of 108 male broilers were assigned to 3 groups (control, 1% sea urchin shell powder, and 1% feed additives with 3 replicates of 12 chicks per pen in a completely randomized design for 28 days. The following parameters have been investigated: proximate composition (DM, CP, EE, and ash, physicochemical properties (pH, TBARS, cooking loss and DPPH radical scavenging, meat color and fatty acid profiles. No remarkable effects between treatment and storage day were observed for proximate composition, physicochemical properties, meat color and fatty acid profiles. In conclusion, diets with 1% sea urchin shell powder have the ability to increase DPPH radical scavenging and unsaturated fatty acid, indicating an opportunity for partial diet substitution in comparison with 1% feed additives.

Environmental properties and microbial communities in coastal waters of Barrow, Alaska from July 11, 2007 to January 14, 2009 (NODC Accession 0073540)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The data set consists of basic water column properties of the Beaufort Sea and the Chukchi Sea near Barrow, Alaska. The environmental properties include salinity,...

Acoustic Doppler current profiling from the JGOFS Arabian Sea cruises aboard the RV T.G. Thompson

Energy Technology Data Exchange (ETDEWEB)

Kim, H.S.; Flagg, C.N.; Shi, Y. [Brookhaven National Lab., Upton, NY (United States). Oceanographic and Atmospheric Sciences Div.

1996-12-01

Acoustic Doppler current profiler (ADCP) data is part of the core data for the US JGOFS Arabian Sea project, along with hydrographic and nutrient data. Seventeen cruises are scheduled to take place between September 1994 and January 1996 on the R/V T.G. Thompson. Seven of the cruises follow a standard cruise track, taking hydrographic, chemical and biological measurements. The rest of the cruises, which take place generally within the standard cruise region defined by a set track, are for the deployment and recovery of moored equipment and towing of a SeaSoar. Detailed description of ADCP hardware, the AutoADCP data acquisition system, and the collection of navigation and compass data on the Thompson is documented in Section 2. Followed by data collection for each cruise together with a cruise track, Section 3 presents the processing and analysis of velocity and acoustic backscatter intensity data. Section 5 shows results of profile quality diagnosis.

Circulation-based Modeling of Gravity Currents

Science.gov (United States)

Meiburg, E. H.; Borden, Z.

2013-05-01

Atmospheric and oceanic flows driven by predominantly horizontal density differences, such as sea breezes, thunderstorm outflows, powder snow avalanches, and turbidity currents, are frequently modeled as gravity currents. Efforts to develop simplified models of such currents date back to von Karman (1940), who considered a two-dimensional gravity current in an inviscid, irrotational and infinitely deep ambient. Benjamin (1968) presented an alternative model, focusing on the inviscid, irrotational flow past a gravity current in a finite-depth channel. More recently, Shin et al. (2004) proposed a model for gravity currents generated by partial-depth lock releases, considering a control volume that encompasses both fronts. All of the above models, in addition to the conservation of mass and horizontal momentum, invoke Bernoulli's law along some specific streamline in the flow field, in order to obtain a closed system of equations that can be solved for the front velocity as function of the current height. More recent computational investigations based on the Navier-Stokes equations, on the other hand, reproduce the dynamics of gravity currents based on the conservation of mass and momentum alone. We propose that it should therefore be possible to formulate a fundamental gravity current model without invoking Bernoulli's law. The talk will show that the front velocity of gravity currents can indeed be predicted as a function of their height from mass and momentum considerations alone, by considering the evolution of interfacial vorticity. This approach does not require information on the pressure field and therefore avoids the need for an energy closure argument such as those invoked by the earlier models. Predictions by the new theory are shown to be in close agreement with direct numerical simulation results. References Von Karman, T. 1940 The engineer grapples with nonlinear problems, Bull. Am. Math Soc. 46, 615-683. Benjamin, T.B. 1968 Gravity currents and related

Intercomparison of Satellite Derived Gravity Time Series with Inferred Gravity Time Series from TOPEX/POSEIDON Sea Surface Heights and Climatological Model Output

Science.gov (United States)

Cox, C.; Au, A.; Klosko, S.; Chao, B.; Smith, David E. (Technical Monitor)

2001-01-01

The upcoming GRACE mission promises to open a window on details of the global mass budget that will have remarkable clarity, but it will not directly answer the question of what the state of the Earth's mass budget is over the critical last quarter of the 20th century. To address that problem we must draw upon existing technologies such as SLR, DORIS, and GPS, and climate modeling runs in order to improve our understanding. Analysis of long-period geopotential changes based on SLR and DORIS tracking has shown that addition of post 1996 satellite tracking data has a significant impact on the recovered zonal rates and long-period tides. Interannual effects such as those causing the post 1996 anomalies must be better characterized before refined estimates of the decadal period changes in the geopotential can be derived from the historical database of satellite tracking. A possible cause of this anomaly is variations in ocean mass distribution, perhaps associated with the recent large El Nino/La Nina. In this study, a low-degree spherical harmonic gravity time series derived from satellite tracking is compared with a TOPEX/POSEIDON-derived sea surface height time series. Corrections for atmospheric mass effects, continental hydrology, snowfall accumulation, and ocean steric model predictions will be considered.

Dissolved inorganic carbon, pH, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the JOHAN HJORT in the Barents Sea, North Greenland Sea and Norwegian Sea from 1993-07-30 to 1993-08-15 (NODC Accession 0113559)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113559 includes chemical, discrete sample, physical and profile data collected from JOHAN HJORT in the Barents Sea, North Greenland Sea and Norwegian...

Dissolved inorganic carbon, pH, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using Alkalinity titrator, CTD and other instruments from METEOR in the Adriatic Sea, Aegean Sea and others from 2011-04-05 to 2011-04-28 (NODC Accession 0108079)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0108079 includes discrete sample and profile data collected from METEOR in the Adriatic Sea, Aegean Sea, Alboran Sea, Ionian Sea, Mediterranean Sea,...

Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from METEOR in the Aegean Sea, Mediterranean Sea and others from 2001-10-18 to 2001-11-11 (NODC Accession 0084620)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0084620 includes discrete sample and profile data collected from METEOR in the Aegean Sea, Mediterranean Sea, Mediterranean Sea - Eastern Basin,...

PH, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using Alkalinity titrator, CTD and other instruments from PROFESSOR SIEDLECKI in the Adriatic Sea, Aegean Sea and others from 1988-11-17 to 1988-11-26 (NCEI Accession 0144306)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0144306 includes discrete sample and profile data collected from PROFESSOR SIEDLECKI in the Adriatic Sea, Aegean Sea, Mediterranean Sea, Mediterranean...

GEOSAT 44: High-Accuracy, High-Resolution Gravity

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This satellite altimeter data base contains precise geoid and gravity anomaly profiles which were constructed from the average of 44 repeat cycles of Geosat. The...

GEOSAT44: High-Accuracy, High-Resolution Gravity

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This satellite altimeter data base contains precise geoid and gravity anomaly profiles which were constructed from the average of 44 repeat cycles of Geosat. The...

Underway pCO2 Measurements in Surface Waters and the Atmosphere During the CGC Healy 2016 Expeditions (NCEI Accession 0166631)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0166631 includes Surface underway data collected from CGC Healy in the North Pacific Ocean, Bering Sea, Chukchi Sea and Arctic Ocean from 2016-06-30...

Proteomic profiles reveal age-related changes in coelomic fluid of sea urchin species with different life spans.

Science.gov (United States)

Bodnar, Andrea

2013-05-01

Sea urchins have a different life history from humans and traditional model organisms used to study the process of aging. Sea urchins grow indeterminately, reproduce throughout their life span and some species have been shown to exhibit negligible senescence with no increase in mortality rate at advanced ages. Despite these properties, different species of sea urchins are reported to have very different natural life spans providing a unique model to investigate cellular mechanisms underlying life span determination and negligible senescence. To gain insight into the biological changes that accompany aging in these animals, proteomic profiles were examined in coelomic fluid from young and old sea urchins of three species with different life spans: short-lived Lytechinus variegatus, long-lived Strongylocentrotus franciscanus and Strongylocentrotus purpuratus which has an intermediate life span. The proteomic profiles of cell-free coelomic fluid were complex with many proteins exhibiting different forms and extensive post-translational modifications. Approximately 20% of the protein spots on 2-D gels showed more than two-fold change with age in each of the species. Changes that are consistent with age in all three species may prove to be useful biomarkers for age-determination for these commercially fished marine invertebrates and also may provide clues to mechanisms of negligible senescence. Among the proteins that change with age, the ectodomain of low-density lipoprotein receptor-related protein 4 (LRP4) was significantly increased in the coelomic fluid of all three sea urchin species suggesting that the Wnt signaling pathway should be further investigated for its role in negligible senescence. Copyright © 2012 Elsevier Inc. All rights reserved.

Raw ODEC Bathy2000 CHIRP subbottom profiler - CHIRP high-resolution Seismic Profile data for the Chukchi Cap and Arctic Ocean.

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — ODEC Bathy2000 CHIRP subbottom profiler - CHIRP high-resolution Seismic Profile data were collected in Raw ODEC Bathy2000 CHIRP dat Datagram Format.

Two-dimensional coherence analysis of magnetic and gravity data from the Casper Quadrangle, Wyoming. Final report

International Nuclear Information System (INIS)

1981-01-01

Volume II contains the following: gravity station location map; complete Bouguer gravity map; total magnetic map; gravity data copper area detrended continued 1 km; magnetic data Casper Wyoming continued 1 km; upward continued coherent gravity maps; magnetic field reduced to the pole/pseudo gravity map; geology map-Casper Quadrangle; magnetic interpretation map-Casper Quadrangle; gravity interpretation map; magnetic interpretation cross section; magnetic profiles; flight line map and uranium occurrences

Bowhead whale body condition and links to summer sea ice and upwelling in the Beaufort Sea

Science.gov (United States)

George, John C.; Druckenmiller, Matthew L.; Laidre, Kristin L.; Suydam, Robert; Person, Brian

2015-08-01

We examined the response of bowhead whale (Balaena mysticetus) body condition to summer sea ice conditions and upwelling-favorable winds. We used a long-term dataset collected from whales of the Bering-Chukchi-Beaufort Seas (BCB) stock to estimate various body condition indices (BCI's) for individual whales that were harvested by Alaskan Eskimos. A series of offshore regions frequented by bowhead whales in summer were delineated and used to quantify interannual summertime environmental conditions including: (a) mean open water fraction, (b) duration of melt season, (c) date of continuous freeze-up, and (d) mean upwelling-favorable wind stress. Body condition was analyzed relative to these metrics for both the preceding summer feeding season and the previous three seasons combined. Our analysis indicates a significant increase in the long-term trend in an axillary girth-based body condition index (BCIG) over the study period (1989-2011). The increase in BCIG is likely associated with the trend in overall reduction of sea ice, including increased duration of open water, changes in upwelling potential (wind stress), and possibly higher primary production in the Pacific Arctic marine ecosystem favoring water-column invertebrates. We found strong significant positive correlations between BCIG and late summer open water fraction in the Beaufort Sea and smaller nearshore areas off the Mackenzie Delta and west of Banks Island. Additionally, BCIG was positively and significantly correlated with duration of melt season, later date of freeze-up in the Beaufort Sea, and upwelling-favorable winds on the Mackenzie shelf and west of Banks Island. A strong seasonal difference in BCI's was noted for subadult bowheads, presumably associated with summer feeding; however, yearlings were found to drop in BCI over at least the first summer after weaning. Our results indicate an overall increase in bowhead whale body condition and a positive correlation with summer sea ice loss over the

Arctic sea-ice ridges—Safe heavens for sea-ice fauna during periods of extreme ice melt?

Science.gov (United States)

Gradinger, Rolf; Bluhm, Bodil; Iken, Katrin

2010-01-01

The abundances and distribution of metazoan within-ice meiofauna (13 stations) and under-ice fauna (12 stations) were investigated in level sea ice and sea-ice ridges in the Chukchi/Beaufort Seas and Canada Basin in June/July 2005 using a combination of ice coring and SCUBA diving. Ice meiofauna abundance was estimated based on live counts in the bottom 30 cm of level sea ice based on triplicate ice core sampling at each location, and in individual ice chunks from ridges at four locations. Under-ice amphipods were counted in situ in replicate ( N=24-65 per station) 0.25 m 2 quadrats using SCUBA to a maximum water depth of 12 m. In level sea ice, the most abundant ice meiofauna groups were Turbellaria (46%), Nematoda (35%), and Harpacticoida (19%), with overall low abundances per station that ranged from 0.0 to 10.9 ind l -1 (median 0.8 ind l -1). In level ice, low ice algal pigment concentrations (Turbellaria, Nematoda and Harpacticoida also were observed in pressure ridges (0-200 ind l -1, median 40 ind l -1), although values were highly variable and only medians of Turbellaria were significantly higher in ridge ice than in level ice. Median abundances of under-ice amphipods at all ice types (level ice, various ice ridge structures) ranged from 8 to 114 ind m -2 per station and mainly consisted of Apherusa glacialis (87%), Onisimus spp. (7%) and Gammarus wilkitzkii (6%). Highest amphipod abundances were observed in pressure ridges at depths >3 m where abundances were up to 42-fold higher compared with level ice. We propose that the summer ice melt impacted meiofauna and under-ice amphipod abundance and distribution through (a) flushing, and (b) enhanced salinity stress at thinner level sea ice (less than 3 m thickness). We further suggest that pressure ridges, which extend into deeper, high-salinity water, become accumulation regions for ice meiofauna and under-ice amphipods in summer. Pressure ridges thus might be crucial for faunal survival during periods of

The Sea-Ice Floe Size Distribution

Science.gov (United States)

Stern, H. L., III; Schweiger, A. J. B.; Zhang, J.; Steele, M.

2017-12-01

The size distribution of ice floes in the polar seas affects the dynamics and thermodynamics of the ice cover and its interaction with the ocean and atmosphere. Ice-ocean models are now beginning to include the floe size distribution (FSD) in their simulations. In order to characterize seasonal changes of the FSD and provide validation data for our ice-ocean model, we calculated the FSD in the Beaufort and Chukchi seas over two spring-summer-fall seasons (2013 and 2014) using more than 250 cloud-free visible-band scenes from the MODIS sensors on NASA's Terra and Aqua satellites, identifying nearly 250,000 ice floes between 2 and 30 km in diameter. We found that the FSD follows a power-law distribution at all locations, with a seasonally varying exponent that reflects floe break-up in spring, loss of smaller floes in summer, and the return of larger floes after fall freeze-up. We extended the results to floe sizes from 10 m to 2 km at selected time/space locations using more than 50 high-resolution radar and visible-band satellite images. Our analysis used more data and applied greater statistical rigor than any previous study of the FSD. The incorporation of the FSD into our ice-ocean model resulted in reduced sea-ice thickness, mainly in the marginal ice zone, which improved the simulation of sea-ice extent and yielded an earlier ice retreat. We also examined results from 17 previous studies of the FSD, most of which report power-law FSDs but with widely varying exponents. It is difficult to reconcile the range of results due to different study areas, seasons, and methods of analysis. We review the power-law representation of the FSD in these studies and discuss some mathematical details that are important to consider in any future analysis.

Chemical and isotopic tracers and other data from the Arctic Ocean from 1990-01-01 to 1999-12-31 (NCEI Accession 0068667)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — These data are water column and sediment data largely collected in the Bering and Chukchi Seas, with some coverage for the Beaufort and East Siberian Seas, and with...

Temperature profile and water depth data collected from COCHRANE in the South China Sea and other seas from 09 January 1987 to 22 February 1987 (NODC Accession 8700095)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and water depth data were collected using BT and XBT from the COCHRANE in the South China and other seas. Data were collected from 09 January...

Atmospheric Profiles, Clouds and the Evolution of Sea Ice Cover in the Beaufort and Chukchi Seas: Atmospheric Observations and Modeling as Part of the Seasonal Ice Zone Reconnaissance Surveys

Science.gov (United States)

2017-06-04

conditions in the SIZ affeCt changes in cloud properties and cover, • develop novel instrumentation including low cost , expendable, air-deployed micro...hour per response, induding the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and...From- To) 04 - 06 - 2017 Final Technical 0/1/01/2012 - 12/31/2016 4. TITLE AND SUBTITLE Sa. CONTRACT NUMBER Atmospheric Profiles , Clouds and the

Errors of Mean Dynamic Topography and Geostrophic Current Estimates in China's Marginal Seas from GOCE and Satellite Altimetry

DEFF Research Database (Denmark)

Jin, Shuanggen; Feng, Guiping; Andersen, Ole Baltazar

2014-01-01

and geostrophic current estimates from satellite gravimetry and altimetry are investigated and evaluated in China's marginal seas. The cumulative error in MDT from GOCE is reduced from 22.75 to 9.89 cm when compared to the Gravity Recovery and Climate Experiment (GRACE) gravity field model ITG-Grace2010 results......The Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) and satellite altimetry can provide very detailed and accurate estimates of the mean dynamic topography (MDT) and geostrophic currents in China's marginal seas, such as, the newest high-resolution GOCE gravity field model GO......-CONS-GCF-2-TIM-R4 and the new Centre National d'Etudes Spatiales mean sea surface model MSS_CNES_CLS_11 from satellite altimetry. However, errors and uncertainties of MDT and geostrophic current estimates from satellite observations are not generally quantified. In this paper, errors and uncertainties of MDT...

Wood Specific Gravity Variations and Biomass of Central African Tree Species: The Simple Choice of the Outer Wood.

Directory of Open Access Journals (Sweden)

Jean-François Bastin

Full Text Available Wood specific gravity is a key element in tropical forest ecology. It integrates many aspects of tree mechanical properties and functioning and is an important predictor of tree biomass. Wood specific gravity varies widely among and within species and also within individual trees. Notably, contrasted patterns of radial variation of wood specific gravity have been demonstrated and related to regeneration guilds (light demanding vs. shade-bearing. However, although being repeatedly invoked as a potential source of error when estimating the biomass of trees, both intraspecific and radial variations remain little studied. In this study we characterized detailed pith-to-bark wood specific gravity profiles among contrasted species prominently contributing to the biomass of the forest, i.e., the dominant species, and we quantified the consequences of such variations on the biomass.Radial profiles of wood density at 8% moisture content were compiled for 14 dominant species in the Democratic Republic of Congo, adapting a unique 3D X-ray scanning technique at very high spatial resolution on core samples. Mean wood density estimates were validated by water displacement measurements. Wood density profiles were converted to wood specific gravity and linear mixed models were used to decompose the radial variance. Potential errors in biomass estimation were assessed by comparing the biomass estimated from the wood specific gravity measured from pith-to-bark profiles, from global repositories, and from partial information (outer wood or inner wood.Wood specific gravity profiles from pith-to-bark presented positive, neutral and negative trends. Positive trends mainly characterized light-demanding species, increasing up to 1.8 g.cm-3 per meter for Piptadeniastrum africanum, and negative trends characterized shade-bearing species, decreasing up to 1 g.cm-3 per meter for Strombosia pustulata. The linear mixed model showed the greater part of wood specific gravity

Wood Specific Gravity Variations and Biomass of Central African Tree Species: The Simple Choice of the Outer Wood.

Science.gov (United States)

Bastin, Jean-François; Fayolle, Adeline; Tarelkin, Yegor; Van den Bulcke, Jan; de Haulleville, Thales; Mortier, Frederic; Beeckman, Hans; Van Acker, Joris; Serckx, Adeline; Bogaert, Jan; De Cannière, Charles

2015-01-01

Wood specific gravity is a key element in tropical forest ecology. It integrates many aspects of tree mechanical properties and functioning and is an important predictor of tree biomass. Wood specific gravity varies widely among and within species and also within individual trees. Notably, contrasted patterns of radial variation of wood specific gravity have been demonstrated and related to regeneration guilds (light demanding vs. shade-bearing). However, although being repeatedly invoked as a potential source of error when estimating the biomass of trees, both intraspecific and radial variations remain little studied. In this study we characterized detailed pith-to-bark wood specific gravity profiles among contrasted species prominently contributing to the biomass of the forest, i.e., the dominant species, and we quantified the consequences of such variations on the biomass. Radial profiles of wood density at 8% moisture content were compiled for 14 dominant species in the Democratic Republic of Congo, adapting a unique 3D X-ray scanning technique at very high spatial resolution on core samples. Mean wood density estimates were validated by water displacement measurements. Wood density profiles were converted to wood specific gravity and linear mixed models were used to decompose the radial variance. Potential errors in biomass estimation were assessed by comparing the biomass estimated from the wood specific gravity measured from pith-to-bark profiles, from global repositories, and from partial information (outer wood or inner wood). Wood specific gravity profiles from pith-to-bark presented positive, neutral and negative trends. Positive trends mainly characterized light-demanding species, increasing up to 1.8 g.cm-3 per meter for Piptadeniastrum africanum, and negative trends characterized shade-bearing species, decreasing up to 1 g.cm-3 per meter for Strombosia pustulata. The linear mixed model showed the greater part of wood specific gravity variance was

Massive gravity from bimetric gravity

International Nuclear Information System (INIS)

Baccetti, Valentina; Martín-Moruno, Prado; Visser, Matt

2013-01-01

We discuss the subtle relationship between massive gravity and bimetric gravity, focusing particularly on the manner in which massive gravity may be viewed as a suitable limit of bimetric gravity. The limiting procedure is more delicate than currently appreciated. Specifically, this limiting procedure should not unnecessarily constrain the background metric, which must be externally specified by the theory of massive gravity itself. The fact that in bimetric theories one always has two sets of metric equations of motion continues to have an effect even in the massive gravity limit, leading to additional constraints besides the one set of equations of motion naively expected. Thus, since solutions of bimetric gravity in the limit of vanishing kinetic term are also solutions of massive gravity, but the contrary statement is not necessarily true, there is no complete continuity in the parameter space of the theory. In particular, we study the massive cosmological solutions which are continuous in the parameter space, showing that many interesting cosmologies belong to this class. (paper)

Neutron stars in screened modified gravity: Chameleon versus dilaton

Science.gov (United States)

Brax, Philippe; Davis, Anne-Christine; Jha, Rahul

2017-04-01

We consider the scalar field profile around relativistic compact objects such as neutron stars for a range of modified gravity models with screening mechanisms of the chameleon and Damour-Polyakov types. We focus primarily on inverse power law chameleons and the environmentally dependent dilaton as examples of both mechanisms. We discuss the modified Tolman-Oppenheimer-Volkoff equation and then implement a relaxation algorithm to solve for the scalar profiles numerically. We find that chameleons and dilatons behave in a similar manner and that there is a large degeneracy between the modified gravity parameters and the neutron star equation of state. This is exemplified by the modifications to the mass-radius relationship for a variety of model parameters.

Other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from unknown platforms in the North Atlantic Ocean, North Sea and Norwegian Sea from 1874-01-01 to 2005-12-31 (NCEI Accession 0144342)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0144342 includes discrete sample and profile data collected from unknown platforms in the North Atlantic Ocean, North Sea and Norwegian Sea from...

First advanced research workshop: Gravity, astrophysics and strings at the Black Sea. Proceedings

International Nuclear Information System (INIS)

Fiziev, P.; Todorov, M.

2002-01-01

The aim of the First Advanced Workshop ‘Gravity, Astrophysics, and Strings’ was: 1)Bringing together scientists from various branches of gravitational physics, astrophysics and string theory gave an opportunity for interdisciplinary exchange of views and enhanced possible collaborations; 2)Provided a unique opportunity to scientists from various countries to communicate with colleagues on the hottest topics of gravitational physics, astrophysics, and string theory; 3) Opened new venue to young talented scientists to communicate and work with major research groups on the topics of the conference. The workshop covered wide aspects of gravity, astrophysics, and string theory concerning the topics: Astrophysics; Mathematical Modeling and Numerical Simulations in Relativity; Astrophysics, and Strings; Relativistic Gravity; (Super)Strings. About 40 participants from Europe, America and Asia gave 30 invited talks and contributed presentations. The full text of 17 of them are included in this book

Temperature profile and pressure data collected from bottle casts in Banda Sea and other areas from BARUNA JAYA I from 08 August 1993 to 25 February 1994 (NODC Accession 0000436)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and pressure data were collected using bottle casts in the Banda Sea, Celebes Sea, Ceram Sea, and Java Sea from BARUNA JAYA I. Data were...

Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the FRANKLIN in the Coral Sea and Tasman Sea from 1993-06-24 to 1993-07-17 (NODC Accession 0116409)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0116409 includes chemical, discrete sample, physical and profile data collected from FRANKLIN in the Coral Sea and Tasman Sea from 1993-06-24 to...

Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the JOHAN HJORT in the North Greenland Sea and Norwegian Sea from 1993-11-06 to 1993-12-02 (NODC Accession 0115679)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115679 includes chemical, discrete sample, physical and profile data collected from JOHAN HJORT in the North Greenland Sea and Norwegian Sea from...

Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the JOHAN HJORT in the North Greenland Sea and Norwegian Sea from 1992-11-05 to 1992-12-01 (NODC Accession 0115403)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115403 includes chemical, discrete sample, physical and profile data collected from JOHAN HJORT in the North Greenland Sea and Norwegian Sea from...

Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the JOHAN HJORT in the North Greenland Sea and Norwegian Sea from 1991-11-05 to 1991-11-27 (NODC Accession 0115685)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115685 includes chemical, discrete sample, physical and profile data collected from JOHAN HJORT in the North Greenland Sea and Norwegian Sea from...

Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the JOHAN HJORT in the North Greenland Sea and Norwegian Sea from 1996-10-30 to 1996-11-10 (NODC Accession 0115680)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115680 includes chemical, discrete sample, physical and profile data collected from JOHAN HJORT in the North Greenland Sea and Norwegian Sea from...

Silkeborg gravity high revisited: Horizontal extension of the source and its uniqueness

DEFF Research Database (Denmark)

Strykowski, Gabriel

2000-01-01

Silkeborg Gravity High is a dominant positive gravity anomaly in Denmark. It is associated with an igneous intrusion within the crust. A deep refraction seismic profile locates the top of the intrusion in depths between 11 km and 25 Inn. The present contribution should be read together with two o...

Comparison of publically available Moho depth and crustal thickness grids with newly derived grids by 3D gravity inversion for the High Arctic region.

Science.gov (United States)

Lebedeva-Ivanova, Nina; Gaina, Carmen; Minakov, Alexander; Kashubin, Sergey

2016-04-01

We derived Moho depth and crustal thickness for the High Arctic region by 3D forward and inverse gravity modelling method in the spectral domain (Minakov et al. 2012) using lithosphere thermal gravity anomaly correction (Alvey et al., 2008); a vertical density variation for the sedimentary layer and lateral crustal variation density. Recently updated grids of bathymetry (Jakobsson et al., 2012), gravity anomaly (Gaina et al, 2011) and dynamic topography (Spasojevic & Gurnis, 2012) were used as input data for the algorithm. TeMAr sedimentary thickness grid (Petrov et al., 2013) was modified according to the most recently published seismic data, and was re-gridded and utilized as input data. Other input parameters for the algorithm were calibrated using seismic crustal scale profiles. The results are numerically compared with publically available grids of the Moho depth and crustal thickness for the High Arctic region (CRUST 1 and GEMMA global grids; the deep Arctic Ocean grids by Glebovsky et al., 2013) and seismic crustal scale profiles. The global grids provide coarser resolution of 0.5-1.0 geographic degrees and not focused on the High Arctic region. Our grids better capture all main features of the region and show smaller error in relation to the seismic crustal profiles compare to CRUST 1 and GEMMA grids. Results of 3D gravity modelling by Glebovsky et al. (2013) with separated geostructures approach show also good fit with seismic profiles; however these grids cover the deep part of the Arctic Ocean only. Alvey A, Gaina C, Kusznir NJ, Torsvik TH (2008). Integrated crustal thickness mapping and plate recon-structions for the high Arctic. Earth Planet Sci Lett 274:310-321. Gaina C, Werner SC, Saltus R, Maus S (2011). Circum-Arctic mapping project: new magnetic and gravity anomaly maps of the Arctic. Geol Soc Lond Mem 35, 39-48. Glebovsky V.Yu., Astafurova E.G., Chernykh A.A., Korneva M.A., Kaminsky V.D., Poselov V.A. (2013). Thickness of the Earth's crust in the

Satellite gravity gradient views help reveal the Antarctic lithosphere

Science.gov (United States)

Ferraccioli, F.; Ebbing, J.; Pappa, F.; Kern, M.; Forsberg, R.

2017-12-01

Here we present and analyse satellite gravity gradient signatures derived from GOCE and superimpose these on tectonic and bedrock topography elements, as well as seismically-derived estimates of crustal thickness for the Antarctic continent. The GIU satellite gravity component images the contrast between the thinner crust and lithosphere underlying the West Antarctic Rift System and the Weddell Sea Rift System and the thicker lithosphere of East Antarctica. The new images also suggest that more distributed wide-mode lithospheric and crustal extension affects both the Ross Sea Embayment and the less well known Ross Ice Shelf segment of the rift system. However, this pattern is less clear towards the Bellingshousen Embayment, indicating that the rift system narrows towards the southern edge of the Antarctic Peninsula. In East Antarctica, the satellite gravity data provides new views into the Archean to Mesoproterozoic Terre Adelie Craton, and clearly shows the contrast wrt to the crust and lithosphere underlying both the Wilkes Subglacial Basin to the east and the Sabrina Subglacial Basin to the west. This finding augments recent interpretations of aeromagnetic and airborne gravity data over the region, suggesting that the Mawson Continent is a composite lithospheric-scale entity, which was affected by several Paleoproterozoic and Mesoproterozoic orogenic events. Thick crust is imaged beneath the Transantarctic Mountains, the Terre Adelie Craton, the Gamburtsev Subglacial Mountains and also Eastern Dronning Maud Land, in particular beneath the recently proposed region of the Tonian Oceanic Arc Superterrane. The GIA and GIU components help delineate the edges of several of these lithospheric provinces. One of the most prominent lithospheric-scale features discovered in East Antarctica from satellite gravity gradient imaging is the Trans East Antarctic Shear Zone that separates the Gamburtsev Province from the Eastern Dronning Maud Land Province and appears to form the

Application of vertical advection-diffusion model for studying CO2 and O2 profiles in central Arabian Sea

Digital Repository Service at National Institute of Oceanography (India)

AnilKumar, N.; Singbal, S.Y.S.

The vertical advection-diffusion model proposed by Craig has been applied to the study of CO sub(2) and O sub(2) profiles in Central Arabian Sea. Distributions of total CO Sub(2) and O sub(2) are explained better by expressions involving exponential...

Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from OCEAN RESEARCHER I in the Philippine Sea and South China Sea from 1991-07-08 to 1991-07-12 (NCEI Accession 0143948)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0143948 includes discrete sample and profile data collected from OCEAN RESEARCHER I in the Philippine Sea and South China Sea (Nan Hai) from...

Weak lensing: Dark Matter, Dark Energy and Dark Gravity

International Nuclear Information System (INIS)

Heavens, Alan

2009-01-01

In this non-specialist review I look at how weak lensing can provide information on the dark sector of the Universe. The review concentrates on what can be learned about Dark Matter, Dark Energy and Dark Gravity, and why. On Dark Matter, results on the confrontation of theoretical profiles with observation are reviewed, and measurements of neutrino masses discussed. On Dark Energy, the interest is whether this could be Einstein's cosmological constant, and prospects for high-precision studies of the equation of state are considered. On Dark Gravity, we consider the exciting prospects for future weak lensing surveys to distinguish General Relativity from extra-dimensional or other gravity theories.

A Gravity data along LARSE (Los Angeles Regional Seismic Experiment) Line II, Southern California

Science.gov (United States)

Wooley, R.J.; Langenheim, V.E.

2001-01-01

The U.S. Geological Survey conducted a detailed gravity study along part of the Los Angeles Regional Seismic Experiment (LARSE) transect across the San Fernando Basin and Transverse Ranges to help characterize the structure underlying this area. 249 gravity measurements were collected along the transect and to augment regional coverage near the profile. An isostatic gravity low of 50-60 mGal reflects the San Fernando-East Ventura basin. Another prominent isostatic gravity with an amplitude of 30 mGal marks the Antelope Valley basin. Gravity highs occur over the Santa Monica Mountains and the Transverse Ranges. The highest isostatic gravity values coincide with outcrops of Pelona schist.

The behavior of surface tension on steady-state rotating fluids in the low gravity environments

Science.gov (United States)

Hung, R. J.; Leslie, Fred W.

1987-01-01

The effect of surface tension on steady-state rotating fluids in a low gravity environment is studied. All the values of the physical parameters used in these calculations, except in the low gravity environments, are based on the measurements carried out by Leslie (1985) in the low gravity environment of a free-falling aircraft. The profile of the interface of two fluids is derived from Laplace's equation relating the pressure drop across an interface to the radii of curvature which has been applied to a low gravity rotating bubble that contacts the container boundary. The interface shape depends on the ratio of gravity to surface tension forces, the ratio of centrifugal to surface tension forces, the contact radius of the interface to the boundary, and the contact angle. The shape of the bubble is symmetric about its equator in a zero-gravity environment. This symmetry disappears and gradually shifts to parabolic profiles as the gravity environment becomes non-zero. The location of the maximum radius of the bubble moves upward from the center of the depth toward the top boundary of the cylinder as gravity increases. The contact radius of interface to the boundary r0 at the top side of cylinder increases and r0 at the bottom side of the cylinder decreases as the gravity environment increases from zero to 1 g.

Dissolved inorganic carbon, alkalinity, temperature, salinity and OXYGEN - APPARENT UTILIZATION (AOU) collected from discrete sample and profile observations using CTD, bottle and other instruments from UNKNOWN PLATFORMS in the Adriatic Sea, Aegean Sea and others from 1874-10-11 to 2000-04-26 (NODC Accession 0117350)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0117350 includes chemical, discrete sample, physical and profile data collected from UNKNOWN PLATFORMS in the Adriatic Sea, Aegean Sea, Alboran Sea,...

Temperature, salinity, nutrients and other profile data from bottle, XBT, and CTD casts in the North Pacific Ocean, Sea of Japan, and other Sea areas by Japan Meteorological Agency (JMA) from 01 January 1965 to 31 December 2002 (NODC Accession 0000972)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Nutrients and temperature profile data were collected using bottle, XBT, and CTD casts in the North Pacific Ocean, Sea of Japan, and other Sea areas from 01 January...

Geophysical survey of the Eggvin Bank and Logi Ridge - Greenland Sea

Science.gov (United States)

Breivik, A. J.; Mjelde, R.; Rai, A. K.; Frassetto, A.

2012-12-01

The northern Greenland Sea has a number of features associated with excess volcanism. These include the Jan Mayen island, the Jan Mayen Plateau north of, and the Eggvin Bank west of Jan Mayen, and the Vesteris Seamount far to the north. In the summer of 2011, we colleced an Ocean Bottom Seismometer (OBS) profile across the Eggvin Bank, returning four good data sets. We also collected single-channel reflection seismic (SCS) data along the OBS line. The profile crosses the transform part of the West Jan Mayen Fracture Zone (WJMFZ), which connects seafloor spreading between the Kolbeinsey and Mohn ridges. Between the WJMFZ and the Vesteris Seamount there is a narrow ridge 170-180 km long, ending in a few seamounts in the east. It disturbs the magnetic seafloor anomalies, and has no conjugate on the Norwegian margin. It thus appears to be younger than the Eocene seafloor it lies on. Trend and position points to Traill Ø in East Greenland, which had magmatism at ~36 Ma. We name it the Logi Ridge after Norse mythology, where Logi is the master of fire, brother of Aegir, master of the sea. We have collected five SCS profiles across this ridge in order to study the surrounding sedimentation pattern. We also collected gravity and magnetic data along all profiles. Initial results show two flat-topped seamounts on the Eggvin Bank, and a flat-topped Logi Ridge, indicating that these have been at sealevel. The sedimentary strata show recent vertical movement north of the WJMFZ near the Jan Mayen Plateau, and compression around the Logi Ridge. Sailing line of R/V Håkon Mosby of Bergen. Survey lines are in bold, and OBS positions are marked by circles.

Sustaining fermentation in high-gravity ethanol production by feeding yeast to a temperature-profiled multifeed simultaneous saccharification and co-fermentation of wheat straw.

Science.gov (United States)

Westman, Johan O; Wang, Ruifei; Novy, Vera; Franzén, Carl Johan

2017-01-01

Considerable progress is being made in ethanol production from lignocellulosic feedstocks by fermentation, but negative effects of inhibitors on fermenting microorganisms are still challenging. Feeding preadapted cells has shown positive effects by sustaining fermentation in high-gravity simultaneous saccharification and co-fermentation (SSCF). Loss of cell viability has been reported in several SSCF studies on different substrates and seems to be the main reason for the declining ethanol production toward the end of the process. Here, we investigate how the combination of yeast preadaptation and feeding, cell flocculation, and temperature reduction improves the cell viability in SSCF of steam pretreated wheat straw. More than 50% cell viability was lost during the first 24 h of high-gravity SSCF. No beneficial effects of adding selected nutrients were observed in shake flask SSCF. Ethanol concentrations greater than 50 g L -1 led to significant loss of viability and prevented further fermentation in SSCF. The benefits of feeding preadapted yeast cells were marginal at later stages of SSCF. Yeast flocculation did not improve the viability but simplified cell harvest and improved the feasibility of the cell feeding strategy in demo scale. Cultivation at 30 °C instead of 35 °C increased cell survival significantly on solid media containing ethanol and inhibitors. Similarly, in multifeed SSCF, cells maintained the viability and fermentation capacity when the temperature was reduced from 35 to 30 °C during the process, but hydrolysis yields were compromised. By combining the yeast feeding and temperature change, an ethanol concentration of 65 g L -1 , equivalent to 70% of the theoretical yield, was obtained in multifeed SSCF on pretreated wheat straw. In demo scale, the process with flocculating yeast and temperature profile resulted in 5% (w/w) ethanol, equivalent to 53% of the theoretical yield. Multifeed SSCF was further developed by means of a

De Sitter space in gauge/gravity duality

Directory of Open Access Journals (Sweden)

Lilia Anguelova

2015-10-01

Full Text Available We investigate gauge/gravity duality for gauge theories in de Sitter space. More precisely, we study a five-dimensional consistent truncation of type IIB supergravity, which encompasses a wide variety of gravity duals of strongly coupled gauge theories, including the Maldacena–Nunez solution and its walking deformations. We find several solutions of the 5d theory with dS4 spacetime and nontrivial profiles for (some of the scalars along the fifth (radial direction. In the process, we prove that one of the equations of motion becomes dependent on the others, for nontrivial warp factor. This dependence reduces the number of field equations and, thus, turns out to be crucial for the existence of solutions with (AdS4 spacetime. Finally, we comment on the implications of our dS4 solutions for building gravity duals of Glueball Inflation.

Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the USCGC POLAR SEA in the North Greenland Sea from 1992-07-15 to 1992-08-14 (NODC Accession 0115687)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115687 includes biological, chemical, discrete sample, physical and profile data collected from USCGC POLAR SEA in the North Greenland Sea from...

Oceanographic profiles of temperature, salinity, nutrients, and plankton in the Mediterranean Sea from the CEAB institute (1979-1997) (NODC Accession 0044830)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Historical profile physical, chemical, and biological data collected in the Mediterranean Sea and submitted by Dr. Antonio Cruzado, head oceanography laboratory, and...

Spatial and temporal multiyear sea ice distributions in the Arctic: A neural network analysis of SSM/I data, 1988-2001

Science.gov (United States)

Belchansky, G.I.; Douglas, D.C.; Alpatsky, I.V.; Platonov, Nikita G.

2004-01-01

Arctic multiyear sea ice concentration maps for January 1988-2001 were generated from SSM/I brightness temperatures (19H, 19V, and 37V) using modified multiple layer perceptron neural networks. Learning data for the neural networks were extracted from ice maps derived from Okean and ERS satellite imagery to capitalize on the stability of active radar multiyear ice signatures. Evaluations of three learning algorithms and several topologies indicated that networks constructed with error back propagation learning and 3-20-1 topology produced the most consistent and physically plausible results. Operational neural networks were developed specifically with January learning data, and then used to estimate daily multiyear ice concentrations from daily-averaged SSM/I brightness temperatures during January. Monthly mean maps were produced for analysis by averaging the respective daily estimates. The 14-year series of January multiyear ice distributions revealed dense and persistent cover in the central Arctic surrounded by expansive regions of highly fluctuating interannual cover. Estimates of total multiyear ice area by the neural network were intermediate to those of other passive microwave algorithms, but annual fluctuations and trends were similar among all algorithms. When compared to Radarsat estimates of multiyear ice concentration in the Beaufort and Chukchi Seas (1997-1999), average discrepancies were small (0.9-2.5%) and spatial coherency was reasonable, indicating the neural network's Okean and ERS learning data facilitated passive microwave inversion that emulated backscatter signatures. During 1988-2001, total January multiyear ice area declined at a significant linear rate of -54.3 x 103 km2/yr-1 (-1.4%/yr-1). The most persistent and extensive decline in multiyear ice concentration (-3.3%/yr-1) occurred in the southern Beaufort and Chukchi Seas. In autumn 1996, a large multiyear ice recruitment of over 106 km2 (mostly in the Siberian Arctic) fully replenished

Dissolved inorganic carbon, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from SAGAR SAMPADA in the Arabian Sea, Indian Ocean and Laccadive Sea from 1994-03-01 to 1995-05-03 (NODC Accession 0117387)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0117387 includes chemical, discrete sample, physical and profile data collected from SAGAR SAMPADA in the Arabian Sea, Indian Ocean and Laccadive Sea...

Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the YMER in the Arctic Ocean, Barents Sea and North Greenland Sea from 1980-08-11 to 1980-09-19 (NODC Accession 0113607)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113607 includes chemical, discrete sample, physical and profile data collected from YMER in the Arctic Ocean, Barents Sea and North Greenland Sea...

On the track of gravity modes: study of the dynamics of the solar core

International Nuclear Information System (INIS)

Mathur, Savita

2007-01-01

This thesis is dedicated to the study of the dynamics of the solar radiative zone through gravity modes. Though the core represents more than 50% of the solar mass, we still do not have an accurate vision of the rotation profile in the very inner part of the Sun. To understand the evolution of stars, we try to put constraints on dynamic processes. Several paths have been followed in this thesis to tackle this issue: solar modeling, the study of a new instrument, observations and inversions of the rotation. The necessity of the detection of gravity modes is driven by the will for a better comprehension of the solar dynamics. With a technological prototype built at the CEA (GOLF-NG), we want to validate a few technical points and prepare the scientific mission which aim will be to detect these gravity modes. We studied first the photodetector and then the whole instrument response. We show the feasibility of the instrument. The observation of the resonance in all the channels proves that it works the way we expected. However, before this mission takes place, the analysis of GOLF data enabled us to detect one gravity-mode candidate as well as the signature of dipole gravity modes. This work benefited from a more theoretical approach on the prediction of gravity-mode frequencies. We show the influence of several physical processes and quantities. Finally, as the dynamical processes in the Sun are not well constrained, we tried to understand the impact of the introduction of one and several gravity modes on the inferred rotation profiles. We also tried to give constraints on the observations so that we could obtain some information on the rotation profile in the core. (author) [fr

Greenland uplift and regional sea level changes from ICESat observations and GIA modelling

DEFF Research Database (Denmark)

Spada, G.; Ruggieri, G.; Sørensen, Louise Sandberg

2012-01-01

‐resolution GrIS mass balance, we study the time‐variations of various geophysical quantities in response to the current mass loss. They include vertical uplift and subsidence, geoid height variations, global patterns of sea level change (or fingerprints), and regional sea level variations along the coasts...... of Greenland. Long‐wavelength uplifts and gravity variations in response to current or past ice thickness variations are obtained solving the sea level equation, which accounts for both the elastic and the viscoelastic components of deformation. To capture the short‐wavelength components of vertical uplift...... in response to current ice mass loss, which is not resolved by satellite gravity observations, we have specifically developed a high‐resolution regional elastic rebound (ER) model. The elastic component of vertical uplift is combined with estimates of the viscoelastic displacement fields associated...

Genomics of Arctic cod

Science.gov (United States)

Wilson, Robert E.; Sage, George K.; Sonsthagen, Sarah A.; Gravley, Megan C.; Menning, Damian; Talbot, Sandra L.

2017-01-01

The Arctic cod (Boreogadus saida) is an abundant marine fish that plays a vital role in the marine food web. To better understand the population genetic structure and the role of natural selection acting on the maternally-inherited mitochondrial genome (mitogenome), a molecule often associated with adaptations to temperature, we analyzed genetic data collected from 11 biparentally-inherited nuclear microsatellite DNA loci and nucleotide sequence data from from the mitochondrial DNA (mtDNA) cytochrome b (cytb) gene and, for a subset of individuals, the entire mitogenome. In addition, due to potential of species misidentification with morphologically similar Polar cod (Arctogadus glacialis), we used ddRAD-Seq data to determine the level of divergence between species and identify species-specific markers. Based on the findings presented here, Arctic cod across the Pacific Arctic (Bering, Chukchi, and Beaufort Seas) comprise a single panmictic population with high genetic diversity compared to other gadids. High genetic diversity was indicated across all 13 protein-coding genes in the mitogenome. In addition, we found moderate levels of genetic diversity in the nuclear microsatellite loci, with highest diversity found in the Chukchi Sea. Our analyses of markers from both marker classes (nuclear microsatellite fragment data and mtDNA cytb sequence data) failed to uncover a signal of microgeographic genetic structure within Arctic cod across the three regions, within the Alaskan Beaufort Sea, or between near-shore or offshore habitats. Further, data from a subset of mitogenomes revealed no genetic differentiation between Bering, Chukchi, and Beaufort seas populations for Arctic cod, Saffron cod (Eleginus gracilis), or Walleye pollock (Gadus chalcogrammus). However, we uncovered significant differences in the distribution of microsatellite alleles between the southern Chukchi and central and eastern Beaufort Sea samples of Arctic cod. Finally, using ddRAD-Seq data, we

Gene Transcript Profiling in Sea Otters Post-Exxon Valdez Oil Spill: A Tool for Marine Ecosystem Health Assessment

Directory of Open Access Journals (Sweden)

Lizabeth Bowen

2016-06-01

Full Text Available Using a panel of genes stimulated by oil exposure in a laboratory study, we evaluated gene transcription in blood leukocytes sampled from sea otters captured from 2006–2012 in western Prince William Sound (WPWS, Alaska, 17–23 years after the 1989 Exxon Valdez oil spill (EVOS. We compared WPWS sea otters to reference populations (not affected by the EVOS from the Alaska Peninsula (2009, Katmai National Park and Preserve (2009, Clam Lagoon at Adak Island (2012, Kodiak Island (2005 and captive sea otters in aquaria. Statistically, sea otter gene transcript profiles separated into three distinct clusters: Cluster 1, Kodiak and WPWS 2006–2008 (higher relative transcription; Cluster 2, Clam Lagoon and WPWS 2010–2012 (lower relative transcription; and Cluster 3, Alaska Peninsula, Katmai and captive sea otters (intermediate relative transcription. The lower transcription of the aryl hydrocarbon receptor (AHR, an established biomarker for hydrocarbon exposure, in WPWS 2010–2012 compared to earlier samples from WPWS is consistent with declining hydrocarbon exposure, but the pattern of overall low levels of transcription seen in WPWS 2010–2012 could be related to other factors, such as food limitation, pathogens or injury, and may indicate an inability to mount effective responses to stressors. Decreased transcriptional response across the entire gene panel precludes the evaluation of whether or not individual sea otters show signs of exposure to lingering oil. However, related studies on sea otter demographics indicate that by 2012, the sea otter population in WPWS had recovered, which indicates diminishing oil exposure.

Gene transcript profiling in sea otters post-Exxon Valdez oil spill: A tool for marine ecosystem health assessment

Science.gov (United States)

Bowen, Lizabeth; Miles, A. Keith; Ballachey, Brenda E.; Waters, Shannon C.; Bodkin, James L.

2016-01-01

Using a panel of genes stimulated by oil exposure in a laboratory study, we evaluated gene transcription in blood leukocytes sampled from sea otters captured from 2006–2012 in western Prince William Sound (WPWS), Alaska, 17–23 years after the 1989 Exxon Valdez oil spill (EVOS). We compared WPWS sea otters to reference populations (not affected by the EVOS) from the Alaska Peninsula (2009), Katmai National Park and Preserve (2009), Clam Lagoon at Adak Island (2012), Kodiak Island (2005) and captive sea otters in aquaria. Statistically, sea otter gene transcript profiles separated into three distinct clusters: Cluster 1, Kodiak and WPWS 2006–2008 (higher relative transcription); Cluster 2, Clam Lagoon and WPWS 2010–2012 (lower relative transcription); and Cluster 3, Alaska Peninsula, Katmai and captive sea otters (intermediate relative transcription). The lower transcription of the aryl hydrocarbon receptor (AHR), an established biomarker for hydrocarbon exposure, in WPWS 2010–2012 compared to earlier samples from WPWS is consistent with declining hydrocarbon exposure, but the pattern of overall low levels of transcription seen in WPWS 2010–2012 could be related to other factors, such as food limitation, pathogens or injury, and may indicate an inability to mount effective responses to stressors. Decreased transcriptional response across the entire gene panel precludes the evaluation of whether or not individual sea otters show signs of exposure to lingering oil. However, related studies on sea otter demographics indicate that by 2012, the sea otter population in WPWS had recovered, which indicates diminishing oil exposure.

A Combined Gravity Compensation Method for INS Using the Simplified Gravity Model and Gravity Database.

Science.gov (United States)

Zhou, Xiao; Yang, Gongliu; Wang, Jing; Wen, Zeyang

2018-05-14

In recent decades, gravity compensation has become an important way to reduce the position error of an inertial navigation system (INS), especially for a high-precision INS, because of the extensive application of high precision inertial sensors (accelerometers and gyros). This paper first deducts the INS's solution error considering gravity disturbance and simulates the results. Meanwhile, this paper proposes a combined gravity compensation method using a simplified gravity model and gravity database. This new combined method consists of two steps all together. Step 1 subtracts the normal gravity using a simplified gravity model. Step 2 first obtains the gravity disturbance on the trajectory of the carrier with the help of ELM training based on the measured gravity data (provided by Institute of Geodesy and Geophysics; Chinese Academy of sciences), and then compensates it into the error equations of the INS, considering the gravity disturbance, to further improve the navigation accuracy. The effectiveness and feasibility of this new gravity compensation method for the INS are verified through vehicle tests in two different regions; one is in flat terrain with mild gravity variation and the other is in complex terrain with fierce gravity variation. During 2 h vehicle tests, the positioning accuracy of two tests can improve by 20% and 38% respectively, after the gravity is compensated by the proposed method.

Sea urchin egg fertilization and development

Science.gov (United States)

Young, R. S.

1971-01-01

The effects of subgravity (much less than unit gravity) on fertilization, cell division, differentiation, and growth of a relatively simple biological system (eggs of the sea urchin Arbacia punctulata) were considered. The experiment was flown on Gemini 3 and recovered as scheduled. However, the experiment objectives were not achieved, primarily for mechanical reasons.

Temperature profile data from the SEA-LAND DEFENDER using bottle, CTD, profiling floats, and XBT casts in a world-wide distribution from 01 January 1990 to 31 December 1990 (NODC Accession 0000386)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile data were collected from the SEA-LAND DEFENDER from January 1, 1990 to December 31, 1990. Data were submitted by Institut Francais De Recherche...

Temperature profile data from the SEA-LAND DEFENDER using bottle, CTD, profiling floats, and XBT casts in a world-wide distribution from 01 January 1991 to 31 December 1991 (NODC Accession 0000387)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile data were collected from the SEA-LAND DEFENDER from January 1, 1991 to December 31, 1991. Data were submitted by the Institut Francais De...

Temperature profile data from the SEA-LAND DEFENDER using bottle, CTD, profiling floats, and XBT casts in a world-wide distribution from 01 January 1998 to 31 December 1998 (NODC Accession 0000394)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile data were collected from the SEA-LAND DEFENDER from January 1, 1998 to December 31, 1998. Data were submitted by the Institut Francais De...

Temperature profile data from the SEA-LAND DEFENDER using bottle, CTD, profiling floats, and XBT casts in a world-wide distribution from 01 January 1997 to 31 December 1997 (NODC Accession 0000393)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile data were collected from the SEA-LAND DEFENDER from January 1, 1997 to December 31, 1997. Data were submitted by the Institut Francais De...

Temperature profile data from the SEA-LAND DEFENDER using bottle, CTD, profiling floats, and XBT casts in a world-wide distribution from 01 January 1994 to 31 December 1994 (NODC Accession 0000390)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile data were collected from the SEA-LAND DEFENDER from January 1, 1994 to December 31, 1994. Data were submitted by Institut Francais De Recherche...

Temperature profile data from the SEA-LAND DEFENDER using bottle, CTD, profiling floats, and XBT casts in a world-wide distribution from 01 January 1993 to 31 December 1993 (NODC Accession 0000389)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile data were collected from the SEA-LAND DEFENDER from January 1, 1993 to December 31, 1993. Data were submitted by Institut Francais De Recherche...

Temperature profile data from the SEA-LAND DEFENDER using bottle, CTD, profiling floats, and XBT casts in a world-wide distribution from 01 January 1999 to 31 December 1999 (NODC Accession 0000395)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile data were collected from the SEA-LAND DEFENDER from January 1, 1999 to December 31, 1999. Data were submitted by the Institut Francais De...

Temperature profile data from the SEA-LAND DEFENDER using bottle, CTD, profiling floats, and XBT casts in a world-wide distribution from 01 January 1992 to 31 December 1992 (NODC Accession 0000388)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile data were collected from the SEA-LAND DEFENDER from January 1, 1992 to December 31, 1992. Data were submitted by Institut Francais De Recherche...

Temperature profile data from the SEA-LAND DEFENDER using bottle, CTD, profiling floats, and XBT casts in a world-wide distribution from 01 January 1995 to 31 December 1995 (NODC Accession 0000391)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile data were collected from the SEA-LAND DEFENDER from January 1, 1995 to December 31, 1995. Data were submitted by Institut Francais De Recherche...

75 FR 76085 - Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for the Polar Bear...

Science.gov (United States)

2010-12-07

... undisturbed habitats; (7) secure resting areas that provide refuge from extreme weather, other bears, or... Seas population, which extends into the Russian Federation (Russia) (Figure 1) (Amstrup et al. 2004a, p... northern Bering Sea and adjacent coastal areas in Alaska and Russia. The eastern boundary of the Chukchi...

Second advanced research workshop: Gravity, astrophysics and strings at the Black Sea. Proceedings

International Nuclear Information System (INIS)

Fiziev, P.; Todorov, M.

2005-01-01

The Second Advanced Workshop ‘Gravity, Astrophysics, and Strings’ held on 10-16 June 2004. It served four purposes: 1) Bringing together scientists from various branches of gravitational physics, astrophysics, and string theory gave an opportunity for interdisciplinary exchange of views and enhanced possible collaborations; 2) Provided a unique opportunity to scientists from various countries to communicate with colleagues on the hottest topics of gravitational physics, astrophysics, and string theory; 3) Opened new venue to young talented scientists to communicate and work with major research groups on the topics of the conference; 4) Stimulated creation of a new generation of young physicists for further development of the above basic topics in fundamental science. The workshop covered wide aspects of gravity, astrophysics, and string theory concerning the topics: Astrophysics; Mathematical Modeling and Numerical Simulations in Relativity; Relativistic Gravity; (Super)Strings. About 35 participants from Europe, America and Asia gave 28 invited talks and contributed presentations. They and guided general discussion as well, which took place confirmed the considerable interest to the themes of the workshop. The full text of 16 of the presented papers are included in this book

Mid-Holocene Strengthening of the Bering Strait Inflow to the Arctic and its Linkage With the North Atlantic Subpolar Gyre Circulation

Science.gov (United States)

Yamamoto, M.; Nam, S. I.; Polyak, L.; Kobayashi, D.; Suzuki, K.; Irino, T.; Shimada, K.

2017-12-01

The Bering Strait inflow (BSI) is an important element of the Arctic Ocean circulation system. We report records of the chlorite/illite ratios in three sediment cores from the northern Chukchi Sea providing insights into the long-term dynamics of the BSI during the Holocene. The BSI approximation by the chlorite/illite record, despite a considerable geographic variability, consistently shows intensified flow from the Bering Sea to the Arctic during the middle Holocene, which is attributed primarily to the effect of higher atmospheric pressure over the Aleutian Basin. The intensified BSI was associated with decrease in sea-ice concentrations and increase in marine production, as indicated by biomarker concentrations, suggesting a major influence of the BSI on sea-ice and biological conditions in the Chukchi Sea. Multi-century to millennial fluctuations, presumably controlled by solar activity, were also identified. This middle Holocene strengthening of the BSI was coeval with intense subpolar gyre circulation in the North Atlantic. We propose that the BSI is linked with the North Atlantic circulation via an atmospheric teleconnection between the Aleutian and Icelandic Lows.

Fragmented Canopies Control the Regimes of Gravity Current Development

Science.gov (United States)

Barcelona, Aina; Serra, Teresa; Colomer, Jordi

2018-03-01

Coastal ecosystems (marine littoral regions, wetlands, and deltas) are regions of high biological productivity. However, they are also one of the world's most threatened ecosystems. Wetlands are characterized by aquatic vegetation adapted to high salinity levels and climatic variations. Wetland canopies buffer these hydrodynamic and atmospheric variations and help retain sediment by reducing current velocity during sea storms or runoff after periods of rain. This work focuses on the effect of the presence of a gap (i.e., nonvegetated zone) parallel to the direction of the main current has on the sedimentation and hydrodynamics of a gravity current. The study aims to (1) address the behavior of a gravity current in a vegetated region compared to one without vegetation (i.e., the gap), (2) determine the effect gap size has on how a gravity current evolves, and 3) determine the effect gap sizes have on the sedimentary rates from a gravity current. Laboratory experiments were carried out in a flume using four different sediment concentrations, four different canopy densities (884, 354, 177, and 0 plants·m-2) and three different gap widths (H/2, H, and 1.5H, where H is the height of the water). This work shows that a gravity current's evolution and its sedimentary rates depend on the fractional volume occupied by the vegetation. While current dynamics in experiments with wider gaps are similar to the nonvegetated case, for smaller gaps the dynamics are closer to the fully vegetated case. Nonetheless, the gravity current exhibits the same behavior in both the vegetated region and the gap.

Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the JOHAN HJORT in the North Greenland Sea and Norwegian Sea from 1994-05-25 to 1994-06-06 (NODC Accession 0113954)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113954 includes chemical, discrete sample, physical and profile data collected from JOHAN HJORT in the North Greenland Sea and Norwegian Sea from...

Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the HAKON MOSBY in the North Greenland Sea and Norwegian Sea from 1998-03-08 to 1998-03-24 (NODC Accession 0113546)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113546 includes chemical, discrete sample, physical and profile data collected from HAKON MOSBY in the North Greenland Sea and Norwegian Sea from...

Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the HAKON MOSBY in the North Greenland Sea and Norwegian Sea from 1997-02-25 to 1997-03-24 (NODC Accession 0113545)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113545 includes chemical, discrete sample, physical and profile data collected from HAKON MOSBY in the North Greenland Sea and Norwegian Sea from...

Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the HAKON MOSBY in the North Greenland Sea and Norwegian Sea from 1994-02-24 to 1994-03-17 (NODC Accession 0113541)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113541 includes chemical, discrete sample, physical and profile data collected from HAKON MOSBY in the North Greenland Sea and Norwegian Sea from...

Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the HAKON MOSBY in the North Greenland Sea and Norwegian Sea from 1994-08-26 to 1994-09-10 (NODC Accession 0113542)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113542 includes chemical, discrete sample, physical and profile data collected from HAKON MOSBY in the North Greenland Sea and Norwegian Sea from...

Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the JOHAN HJORT in the North Greenland Sea and Norwegian Sea from 1995-04-27 to 1995-05-23 (NODC Accession 0113561)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113561 includes chemical, discrete sample, physical and profile data collected from JOHAN HJORT in the North Greenland Sea and Norwegian Sea from...

Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the JOHAN HJORT in the North Greenland Sea and Norwegian Sea from 1995-11-08 to 1995-11-26 (NODC Accession 0113562)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113562 includes chemical, discrete sample, physical and profile data collected from JOHAN HJORT in the North Greenland Sea and Norwegian Sea from...

Eigenvector of gravity gradient tensor for estimating fault dips considering fault type

Science.gov (United States)

Kusumoto, Shigekazu

2017-12-01

The dips of boundaries in faults and caldera walls play an important role in understanding their formation mechanisms. The fault dip is a particularly important parameter in numerical simulations for hazard map creation as the fault dip affects estimations of the area of disaster occurrence. In this study, I introduce a technique for estimating the fault dip using the eigenvector of the observed or calculated gravity gradient tensor on a profile and investigating its properties through numerical simulations. From numerical simulations, it was found that the maximum eigenvector of the tensor points to the high-density causative body, and the dip of the maximum eigenvector closely follows the dip of the normal fault. It was also found that the minimum eigenvector of the tensor points to the low-density causative body and that the dip of the minimum eigenvector closely follows the dip of the reverse fault. It was shown that the eigenvector of the gravity gradient tensor for estimating fault dips is determined by fault type. As an application of this technique, I estimated the dip of the Kurehayama Fault located in Toyama, Japan, and obtained a result that corresponded to conventional fault dip estimations by geology and geomorphology. Because the gravity gradient tensor is required for this analysis, I present a technique that estimates the gravity gradient tensor from the gravity anomaly on a profile.

Late Quaternary Variability of Arctic Sea Ice: Insights From Biomarker Proxy Records and Model Simulations

Science.gov (United States)

Stein, R. H.; Fahl, K.; Gierz, P.; Niessen, F.; Lohmann, G.

2017-12-01

Over the last about four decades, coinciding with global warming and atmospheric CO2increase, the extent and thickness of Arctic sea ice has decreased dramatically, a decrease much more rapid than predicted by climate models. The driving forces of this change are still not fully understood. In this context, detailed paleoclimatic records going back beyond the timescale of direct observations, i.e., high-resolution Holocene records but also records representing more distant warm periods, may help to to distinguish and quantify more precisely the natural and anthropogenic greenhouse gas forcing of global climate change and related sea ice decrease. Here, we concentrate on sea ice biomarker records representing the penultimate glacial/last interglacial (MIS 6/MIS 5e) and the Holocene time intervals. Our proxy records are compared with climate model simulations using a coupled atmosphere-ocean general circulation model (AOGCM). Based on our data, polynya-type sea ice conditions probably occurred off the major ice sheets along the northern Barents and East Siberian continental margins during late MIS 6. Furthermore, we demonstrate that even during MIS 5e, i.e., a time interval when the high latitudes have been significantly warmer than today, sea ice existed in the central Arctic Ocean during summer, whereas sea ice was significantly reduced along the Barents Sea continental margin influenced by Atlantic Water inflow. Assuming a closed Bering Strait (no Pacific Water inflow) during early MIS 5, model simulations point to a significantly reduced sea ice cover in the central Arctic Ocean, a scenario that is however not supported by the proxy record and thus seems to be less realistic. Our Holocene biomarker proxy records from the Chukchi Sea indicate that main factors controlling the millennial Holocene variability in sea ice are probably changes in surface water and heat flow from the Pacific into the Arctic Ocean as well as the long-term decrease in summer insolation

Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample, profile and time series profile observations using Alkalinity titrator, CTD and other instruments from POLARFRONT in the Norwegian Sea from 2001-10-31 to 2007-11-29 (NODC Accession 0112884)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0112884 includes chemical, discrete sample, physical, profile and time series profile data collected from POLARFRONT in the Norwegian Sea from...

Mass-induced sea level variations in the Red Sea from GRACE, steric-corrected altimetry, in situ bottom pressure records, and hydrographic observations

Science.gov (United States)

Feng, W.; Lemoine, J.-M.; Zhong, M.; Hsu, H. T.

2014-08-01

An annual amplitude of ∼18 cm mass-induced sea level variations (SLV) in the Red Sea is detected from the Gravity Recovery and Climate Experiment (GRACE) satellites and steric-corrected altimetry from 2003 to 2011. The annual mass variations in the region dominate the mean SLV, and generally reach maximum in late January/early February. The annual steric component of the mean SLV is relatively small (mass-induced SLV. In situ bottom pressure records at the eastern coast of the Red Sea validate the high mass variability observed by steric-corrected altimetry and GRACE. In addition, the horizontal water mass flux of the Red Sea estimated from GRACE and steric-corrected altimetry is validated by hydrographic observations.

Gravity and Areomagnetic Signatures and their Geological Significance in the Abu Gharadig Basin, Nortwestern Desert, Egypt

International Nuclear Information System (INIS)

Ibrahim, H.A.

2000-01-01

Geological interpretation of Bouguer gravity anomalies and total intensity magnetic anomalies of two profiles from the Abu Gharadig Basin suggests a general northward increase in basement depth (about 3 to 6 km). Gravity modeling using software given by Enmark (1981) and Beg et. al (1987) are applied along the gravity profiles, giving reliable results agreeing with the available geological information on the area. The magenetic profiles are interpreted and analyzed using two methods: non-linear optimization techniques and interactive techniques. A prominent uplift of the basement rock is observed to the south, which is considered a part of the major basement high in the north Western Desert of the Egypt. In addition a significant deepning of the basement is found to the north, which represents a part of the major subsidence including the present Mediterranean BasinThe abnormal thickness of the sedimentary section of varius facies, and the presence of deep-causative intrabasement (acidic or basic bodies) are possibly considered the main cause for 1) the origin of different gravity anamolies (negative and positive respectively); and 2) the origin of different magnetic anomalies (low and high), particularly those in the middle part of the study area. (author)

Stealth configurations in vector-tensor theories of gravity

Science.gov (United States)

Chagoya, Javier; Tasinato, Gianmassimo

2018-01-01

Studying the physics of compact objects in modified theories of gravity is important for understanding how future observations can test alternatives to General Relativity. We consider a subset of vector-tensor Galileon theories of gravity characterized by new symmetries, which can prevent the propagation of the vector longitudinal polarization, even in absence of Abelian gauge invariance. We investigate new spherically symmetric and slowly rotating solutions for these systems, including an arbitrary matter Lagrangian. We show that, under certain conditions, there always exist stealth configurations whose geometry coincides with solutions of Einstein gravity coupled with the additional matter. Such solutions have a non-trivial profile for the vector field, characterized by independent integration constants, which extends to asymptotic infinity. We interpret our findings in terms of the symmetries and features of the original vector-tensor action, and on the number of degrees of freedom that it propagates. These results are important to eventually describe gravitationally bound configurations in modified theories of gravity, such as black holes and neutron stars, including realistic matter fields forming or surrounding the object.

Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the HAKON MOSBY in the Barents Sea and Norwegian Sea from 2001-08-22 to 2001-08-29 (NODC Accession 0113887)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113887 includes chemical, discrete sample, physical and profile data collected from HAKON MOSBY in the Barents Sea and Norwegian Sea from 2001-08-22...

Lorentz invariance violation in modified gravity

International Nuclear Information System (INIS)

Brax, Philippe

2012-01-01

We consider an environmentally dependent violation of Lorentz invariance in scalar-tensor models of modified gravity where General Relativity is retrieved locally thanks to a screening mechanism. We find that fermions have a modified dispersion relation and would go faster than light in an anisotropic and space-dependent way along the scalar field lines of force. Phenomenologically, these models are tightly restricted by the amount of Cerenkov radiation emitted by the superluminal particles, a constraint which is only satisfied by chameleons. Measuring the speed of neutrinos emitted radially from the surface of the earth and observed on the other side of the earth would probe the scalar field profile of modified gravity models in dense environments. We argue that the test of the equivalence principle provided by the Lunar ranging experiment implies that a deviation from the speed of light, for natural values of the coupling scale between the scalar field and fermions, would be below detectable levels, unless gravity is modified by camouflaged chameleons where the field normalisation is environmentally dependent.

Lorentz invariance violation in modified gravity

Energy Technology Data Exchange (ETDEWEB)

Brax, Philippe, E-mail: philippe.brax@cea.fr [Institut de Physique Theorique, CEA, IPhT, CNRS, URA 2306, F-91191Gif/Yvette Cedex (France)

2012-06-06

We consider an environmentally dependent violation of Lorentz invariance in scalar-tensor models of modified gravity where General Relativity is retrieved locally thanks to a screening mechanism. We find that fermions have a modified dispersion relation and would go faster than light in an anisotropic and space-dependent way along the scalar field lines of force. Phenomenologically, these models are tightly restricted by the amount of Cerenkov radiation emitted by the superluminal particles, a constraint which is only satisfied by chameleons. Measuring the speed of neutrinos emitted radially from the surface of the earth and observed on the other side of the earth would probe the scalar field profile of modified gravity models in dense environments. We argue that the test of the equivalence principle provided by the Lunar ranging experiment implies that a deviation from the speed of light, for natural values of the coupling scale between the scalar field and fermions, would be below detectable levels, unless gravity is modified by camouflaged chameleons where the field normalisation is environmentally dependent.

Newtonian gravity in loop quantum gravity

OpenAIRE

Smolin, Lee

2010-01-01

We apply a recent argument of Verlinde to loop quantum gravity, to conclude that Newton's law of gravity emerges in an appropriate limit and setting. This is possible because the relationship between area and entropy is realized in loop quantum gravity when boundaries are imposed on a quantum spacetime.

Effects of dietary n-3 highly unsaturated fatty acids (HUFAs) on growth, fatty acid profiles, antioxidant capacity and immunity of sea cucumber Apostichopus japonicus (Selenka).

Science.gov (United States)

Yu, Haibo; Gao, Qinfeng; Dong, Shuanglin; Zhou, Jishu; Ye, Zhi; Lan, Ying

2016-07-01

The present study was conducted to understand the effects of dietary n-3 highly unsaturated fatty acids (HUFAs) on growth, fatty acid profiles, antioxidant capacity and the immunity of sea cucumber Apostichopus japonicus (Selenka). Five experimental diets were prepared, containing graded levels of n-3 HUFAs (0.46%, 0.85%, 1.25%, 1.61% and 1.95%, respectively), and the 0.46% group was used as control group. The specific growth rates, fatty acid profiles, activities and gene expression of antioxidative enzymes and lysozyme of the sea cucumbers that were fed with the 5 experimental diets were determined. The results showed that the specific growth rate of sea cucumbers in all the treatment groups significantly increased compared to the control group (P sea cucumbers. The contents of eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) in the body wall of the sea cucumbers gradually increased with the increasing levels of n-3 HUFAs in the diets. The suitable supplement of n-3 HUFAs in diets improved the activities of superoxide dismutase (SOD) and catalase (CAT) of sea cucumbers by up-regulating the expression of SOD and CAT mRNA in sea cucumbers. However, excess n-3 HUFAs in diets caused lipid peroxidation, inhibited the expression of lysozyme (LSZ) mRNA and decreased the activities of LSZ in sea cucumbers. In summary, the suitable supplement levels of n-3 HUFAs in diets of sea cucumbers A. japonicus were estimated between 0.85% and 1.25% considering the growth performance, cost and the indicators of antioxidant capacity and immunity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Oceanographic profile temperature, salinity, oxygen measurements collected using bottle from multiple platforms in the Azov, Black Seas from 1924-1990 (NODC Accession 0002717)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Oceanographic profile temperature, salinity, oxygen measurements collected using bottle from multiple platforms in the Azov, Black Seas from 1924-1990

Assessing GOCE Gravity Models using Altimetry and Drifters

DEFF Research Database (Denmark)

Knudsen, Per; Andersen, Ole Baltazar

The improved gravity models provided by the GOCE mission have enhanced the resolution and sharpened the boundaries of those features and the associated geostrophic surface currents reveal improvements for all of the ocean’s current systems. There are still important signals to be recovered...... and issues related to errors in the models have been identified.In this study, a series of newer gravity models including observations from GRACE and GOCE are compared with the DTU15MSS mean sea surface to analyse resolution capacities and to identify issues caused by errors in the models. The comparisons...... are carried out in regional analyses using Fourier techniques to derive the spectral characteristics as well as anisotropic patterns to identify differences and to quantify quality measures associated with the models. In addition, regional analyses are carried out using in-situ observations of the geostrophic...

Ocean Acidification in the Surface Waters of the Pacific-Arctic Boundary Regions

Science.gov (United States)

Mathis, J. T.; Cross, J. N.; Evans, W.; Doney, S. C.

2016-02-01

The continental shelves of the Pacific-Arctic Region (PAR) are especially vulnerable to the effects of ocean acidification (OA) because the intrusion of anthropogenic CO2 is not the only process that can reduce pH and carbonate mineral saturation states for aragonite (ΩArag). Enhanced sea-ice melt, respiration of organic matter, upwelling and riverine inputs have been shown to exacerbate CO2-driven ocean acidification in high-latitude regions. Additionally, the indirect effect of changing sea-ice coverage is providing a positive feedback to OA as more open water will allow for greater uptake of atmospheric CO2. Here, we compare model-based outputs from the Community Earth System Model with a subset of recent ship-based observations, and take an initial look at future model projections of surface water ΩArag in the Bering, Chukchi and Beaufort Seas. We then use the model outputs to define benchmark years when biological impacts are likely to result from reduced ΩArag. Each of the three continental shelf seas in the PAR will become undersaturated with respect to aragonite at approximately 30-year intervals, indicating that aragonite undersaturations gradually progress upstream along the flow path of the waters as they move north from the Pacific Ocean. However, naturally high variability in ΩArag may indicate higher resilience of the Bering Sea ecosystem to these low-ΩArag conditions than the Chukchi and the Beaufort Seas. Based on our initial results, we have determined that the annual mean for ΩArag will pass below the current range of natural variability in 2025 for the Beaufort Sea and 2027 for the Chukchi Sea. Because of the higher range of natural variability, the annual mean for ΩArag for the Bering Sea does not pass out of the natural variability range until 2044. As ΩArag in these shelf seas slips below the present-day range of large seasonal variability by midcentury, it could put tremendous pressure on the diverse ecosystems that support some of

Gravity signals from the lithosphere in the Central European Basin System

Science.gov (United States)

Yegorova, T.; Bayer, U.; Thybo, H.; Maystrenko, Y.; Scheck-Wenderoth, M.; Lyngsie, S. B.

2007-01-01

We study the gravity signals from different depth levels in the lithosphere of the Central European Basin System (CEBS). The major elements of the CEBS are the Northern and Southern Permian Basins which include the Norwegian-Danish Basin (NDB), the North-German Basin (NGB) and the Polish Trough (PT). An up to 10 km thick sedimentary cover of Mesozoic-Cenozoic sediments, hides the gravity signal from below the basin and masks the heterogeneous structure of the consolidated crust, which is assumed to be composed of domains that were accreted during the Paleozoic amalgamation of Europe. We performed a three-dimensional (3D) gravity backstripping to investigate the structure of the lithosphere below the CEBS. Residual anomalies are derived by removing the effect of sediments down to the base of Permian from the observed field. In order to correct for the influence of large salt structures, lateral density variations are incorporated. These sediment-free anomalies are interpreted to reflect Moho relief and density heterogeneities in the crystalline crust and uppermost mantle. The gravity effect of the Moho relief compensates to a large extent the effect of the sediments in the CEBS and in the North Sea. Removal of the effects of large-scale crustal inhomogeneities shows a clear expression of the Variscan arc system at the southern part of the study area and the old crust of Baltica further north-east. The remaining residual anomalies (after stripping off the effects of sediments, Moho topography and large-scale crustal heterogeneities) reveal long wavelength anomalies, which are caused mainly by density variations in the upper mantle, though gravity influence from the lower crust cannot be ruled out. They indicate that the three main subbasins of the CEBS originated on different lithospheric domains. The PT originated on a thick, strong and dense lithosphere of the Baltica type. The NDB was formed on a weakened Baltica low-density lithosphere formed during the Sveco

Chiral gravity, log gravity, and extremal CFT

International Nuclear Information System (INIS)

Maloney, Alexander; Song Wei; Strominger, Andrew

2010-01-01

We show that the linearization of all exact solutions of classical chiral gravity around the AdS 3 vacuum have positive energy. Nonchiral and negative-energy solutions of the linearized equations are infrared divergent at second order, and so are removed from the spectrum. In other words, chirality is confined and the equations of motion have linearization instabilities. We prove that the only stationary, axially symmetric solutions of chiral gravity are BTZ black holes, which have positive energy. It is further shown that classical log gravity--the theory with logarithmically relaxed boundary conditions--has finite asymptotic symmetry generators but is not chiral and hence may be dual at the quantum level to a logarithmic conformal field theories (CFT). Moreover we show that log gravity contains chiral gravity within it as a decoupled charge superselection sector. We formally evaluate the Euclidean sum over geometries of chiral gravity and show that it gives precisely the holomorphic extremal CFT partition function. The modular invariance and integrality of the expansion coefficients of this partition function are consistent with the existence of an exact quantum theory of chiral gravity. We argue that the problem of quantizing chiral gravity is the holographic dual of the problem of constructing an extremal CFT, while quantizing log gravity is dual to the problem of constructing a logarithmic extremal CFT.

Diatom Surface Sediment Assemblages from the Bering Sea Shelf: a Tossed Salad or Faithful Recorder of 50 Years of Environmental Change?

Science.gov (United States)

Caissie, B.; Brigham-Grette, J.; Kanamaru-Shinn, K.

2010-12-01

Recent environmental change in the Bering Sea includes a shift from the negative to positive phase of the Pacific Decadal Oscillation in 1976/77, a secondary shift in sea level pressure and sea surface temperatures in 1998, increasing sea surface temperatures, an earlier spring, an increase in the number of days that sea ice is present along the shelf-slope break, and a decrease in the number of days that sea ice is present in the Chukchi Sea and Arctic Ocean. These physical changes have manifest biological changes such as a northward migration of invertebrates and fish from the southern Bering Sea and shifts in the timing and duration of sea-ice related primary productivity and the spring bloom. We aim to see if diatom sediment assemblages are faithful recorders of these ecological changes in the Bering Sea or if bioturbation has essentially mixed today’s rapid change down core such that the signal is either muted or no longer apparent. Six continental shelf areas were examined in the Bering Sea ranging from northeast of St. Lawrence Island to the shelf-slope break in the south-central Bering Sea. Diatom assemblages from core tops collected as part of the PROBES program in the 1960s were compared to core tops taken nearby (7 m) multi-year ice so their decline may be related to the decrease in multi-year ice over the past 30 years. Additionally, in most cases, species diversity has declined over the past 50 years with Fragilariopsis oceanica and Fragilariopsis cylindrus accounting for a greater percentage of the sediment assemblages today. These two species are collectively considered indicators of seasonal sea ice; their relative abundance peaks when ice is present for 5 months per year. Ongoing down core analyses in these six areas will further reveal the nature of these assemblage changes.

Gravity and magnetic data of Fortymile Wash, Nevada Test Site, Nevada

International Nuclear Information System (INIS)

Ponce, D.A.; Kohrn, S.B.; Waddell, S.

1992-01-01

Gravity and ground magnetic data collected along six traverses across Fortymile Wash, in the southwest quadrant of the Nevada Test Site suggest that there are no significant vertical offsets below Fortymile Wash. The largest gravity and magnetic anomaly, in the vicinity of Fortymile Wash, is produced by the Paintbrush fault, on the west flank of Fran Ridge. Inferred vertical offset is about 250 ± 60 m (800 ± 200 ft). Geophysical data indicate that the fault is about 300 m (1,000 ft) east of its mapped, but concealed location. North of Busted Butte, near Fran Ridge, geophysical data do not preclude the existence of small vertical offsets bounding Fortymile Wash. However, gravity and magnetic profiles south of Busted Butte show little correlation to those to the north and suggest that vertical offsets, comparable in size to the Paintbrush fault, are not present. Density profiling, a technique used to determine the average density of small topographic features, suggests that the density of near-surface material in the vicinity of Fortymile Wash is 1.80 to 2.00 g/cm 3

The Lighter Side of Gravity

Science.gov (United States)

Narlikar, Jayant Vishnu

1996-10-01

From the drop of an apple to the stately dance of the galaxies, gravity is omnipresent in the Cosmos. Even with its high profile, gravity is the most enigmatic of all the known basic forces in nature. The Lighter Side of Gravity presents a beautifully clear and completely nontechnical introduction to the phenomenon of this force in all its manifestations. Astrophysicist Jayant Narlikar begins with an historical background to the discovery of the law of gravitation by Isaac Newton in the seventeenth century. Using familiar analogies, interesting anecdotes, and numerous illustrations to get across subtle effects and difficult points to readers, he goes on to describe the general theory of relativity and some of its strange and unfamiliar ideas such as curved spacetime, the bending of light, and black holes. Since first publication in 1982 (W.H. Freeman), Dr. Narlikar has brought his book completely up to date and expanded it to include the discovery of gigantic gravitational lenses in space, the findings of the Cosmic Background Explorer (COBE) satellite, the detection of dark matter in galaxies, the investigation of the very early Universe, and other new ideas in cosmology. This lucid and stimulating book presents a clear approach to the intriguing phenomenon of gravity for everyone who has ever felt caught in its grip. Jayant Narlikar is the winner of many astronomical prizes and the author of Introduction to Cosmology (Cambridge University Press, 1993).

Field verification of ADCP surface gravity wave elevation spectra

NARCIS (Netherlands)

Hoitink, A.J.F.; Peters, H.C.; Schroevers, M.

2007-01-01

Acoustic Doppler current profilers (ADCPs) can measure orbital velocities induced by surface gravity waves, yet the ADCP estimates of these velocities are subject to a relatively high noise level. The present paper introduces a linear filtration technique to significantly reduce the influence of

Late Quaternary faunal change in coastal Arabian sea sediments

Digital Repository Service at National Institute of Oceanography (India)

Borole, D.V.; Rao, K.K; Krishnamurthy, R.V.; Somayajulu, B.L.K

Carbonate content and faunal composition of two gravity cores from the coastal Arabian Sea provide evidence of a major environmental change in surface ocean waters about 13,000 yr B.P. Radiocarbon dating indicates that deposition rates ranged from 1...

Semi-Infinite Geology Modeling Algorithm (SIGMA): a Modular Approach to 3D Gravity

Science.gov (United States)

Chang, J. C.; Crain, K.

2015-12-01

Conventional 3D gravity computations can take up to days, weeks, and even months, depending on the size and resolution of the data being modeled. Additional modeling runs, due to technical malfunctions or additional data modifications, only compound computation times even further. We propose a new modeling algorithm that utilizes vertical line elements to approximate mass, and non-gridded (point) gravity observations. This algorithm is (1) magnitudes faster than conventional methods, (2) accurate to less than 0.1% error, and (3) modular. The modularity of this methodology means that researchers can modify their geology/terrain or gravity data, and only the modified component needs to be re-run. Additionally, land-, sea-, and air-based platforms can be modeled at their observation point, without having to filter data into a synthesized grid.

ADCP measurements of gravity currents in the Chicago River, Illinois

Science.gov (United States)

Garcia, C.M.; Oberg, K.; Garcia, M.H.

2007-01-01

A unique set of observations of stratified flow phenomena in the Chicago River was made using an upward-looking acoustic Doppler current profiler (ADCP) during the period November 20, 2003 to February 1, 2004. Water density differences between the Chicago River and its North Branch (NB) seem to be responsible for the development of gravity currents. With the objective of characterizing the occurrence, frequency, and evolution of such currents, the ADCP was configured to continuously collect high-resolution water velocity and echo intensity profiles in the Chicago River at Columbus Drive. During the observation period, 28 gravity current events were identified, lasting a total of 77% of the time. Sixteen of these events were generated by underflows from the NB and 12 of these events were generated by overflows from the NB. On average, the duration of the underflow and overflow events was 52.3 and 42.1 h, respectively. A detailed analysis of one underflow event, which started on January 7, 2004, and lasted about 65h, was performed. This is the first time that ADCP technology has been used to continuously monitor gravity currents in a river. ?? 2007 ASCE.

Stratigraphic, regional unconformity analysis and potential petroleum plays of East Siberian Sea Basin

Science.gov (United States)

Karpov, Yury; Stoupakova, Antonina; Suslova, Anna; Agasheva, Mariia

2017-04-01

The East Siberian Sea basin (ESSB) one of the most unexplored part of the Russian Arctic shelf, extending for over 1000 km from New Siberian Islands archipelago to Wrangel Island. This region is considered as a region with probable high petroleum potential. Within the ESSB several phases of orogeny are recognized [1]: Elsmerian orogeny in Early Devonian, Early Brooks orogeny in Early Cretaceous, Late Brooks orogeny in Late Cretaceous. Two generations of the basins could be outlined. Both of these generations are controlled by the basement domains [1]: Paleozoic (post-Devonian) to Mesozoic basins preserved north of the Late Mesozoic frontal thrusts; Aptian-Albian to Quaternary basins, postdating the Verkhoyansk-Brookian orogeny, and evolving mainly over the New-Siberian-Chukchi Fold Belt. Basin is filled with siliclastic sediments and in the deepest depocentres sediments thickness exceeds 8-10 km in average. Seismic data was interpreted using methods of seismic stratigraphy. Finally, main seismic horizons were indicated and each horizon follows regional stratigraphic unconformities: mBU - in base of Cenozoic, BU - in base of Upper Cretaceous, LCU - in base of Cretaceous, JU - in middle of Jurassic, F - in top of Basement. In ESSB, we can identify Permian, Triassic, Jurassic, Cretaceous, Paleogene and Neogene seismic stratigraphy complexes. Perspective structures, investigated in ESSB were founded out by comparing seismogeological cross-sections with explored analogs in other onshore and offshore basins [2, 3, 4]. The majority of structures could be connected with stratigraphic and fault traps. The most perspective prospects are probably connected with grabens and depressions, where thickness of sediments exceed 10 km. Reservoirs in ESSB are proposed by regional geological explorations on New Siberian Islands Archipelago and Wrangel Island. Potential seals are predominantly assigned to Jurassic and Cretaceous periods. Thick clinoform units of various geometry and

General Relativity solutions in modified gravity

Science.gov (United States)

Motohashi, Hayato; Minamitsuji, Masato

2018-06-01

Recent gravitational wave observations of binary black hole mergers and a binary neutron star merger by LIGO and Virgo Collaborations associated with its optical counterpart constrain deviation from General Relativity (GR) both on strong-field regime and cosmological scales with high accuracy, and further strong constraints are expected by near-future observations. Thus, it is important to identify theories of modified gravity that intrinsically possess the same solutions as in GR among a huge number of theories. We clarify the three conditions for theories of modified gravity to allow GR solutions, i.e., solutions with the metric satisfying the Einstein equations in GR and the constant profile of the scalar fields. Our analysis is quite general, as it applies a wide class of single-/multi-field scalar-tensor theories of modified gravity in the presence of matter component, and any spacetime geometry including cosmological background as well as spacetime around black hole and neutron star, for the latter of which these conditions provide a necessary condition for no-hair theorem. The three conditions will be useful for further constraints on modified gravity theories as they classify general theories of modified gravity into three classes, each of which possesses i) unique GR solutions (i.e., no-hair cases), ii) only hairy solutions (except the cases that GR solutions are realized by cancellation between singular coupling functions in the Euler-Lagrange equations), and iii) both GR and hairy solutions, for the last of which one of the two solutions may be selected dynamically.

Dissolved inorganic carbon, pH, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the JOHAN HJORT in the North Greenland Sea and Norwegian Sea from 1997-04-14 to 1997-05-22 (NODC Accession 0113563)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113563 includes chemical, discrete sample, physical and profile data collected from JOHAN HJORT in the North Greenland Sea and Norwegian Sea from...

Dissolved inorganic carbon, pH, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the HAKON MOSBY in the North Greenland Sea and Norwegian Sea from 1995-02-17 to 1995-03-18 (NODC Accession 0113543)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113543 includes chemical, discrete sample, physical and profile data collected from HAKON MOSBY in the North Greenland Sea and Norwegian Sea from...

Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the JAMES CLARK ROSS in the North Greenland Sea and Norwegian Sea from 1996-07-20 to 1996-08-22 (NODC Accession 0113757)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113757 includes chemical, discrete sample, physical and profile data collected from JAMES CLARK ROSS in the North Greenland Sea and Norwegian Sea...

Dissolved inorganic carbon, pH, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the JOHAN HJORT in the North Greenland Sea and Norwegian Sea from 1998-08-01 to 1998-08-23 (NODC Accession 0113758)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113758 includes chemical, discrete sample, physical and profile data collected from JOHAN HJORT in the North Greenland Sea and Norwegian Sea from...

Study of southern CHAONAN sag lower continental slope basin deposition character in Northern South China Sea

Science.gov (United States)

Tang, Y.

2009-12-01

Northern South China Sea Margin locates in Eurasian plate,Indian-Australia plate,Pacific Plates.The South China Sea had underwent a complicated tectonic evolution in Cenozoic.During rifting,the continental shelf and slope forms a series of Cenozoic sedimentary basins,including Qiongdongnan basin,Pearl River Mouth basin,Taixinan basin.These basins fill in thick Cenozoic fluviolacustrine facies,transitional facies,marine facies,abyssal facies sediment,recording the evolution history of South China Sea Margin rifting and ocean basin extending.The studies of tectonics and deposition of depression in the Southern Chaonan Sag of lower continental slope in the Norther South China Sea were dealt with,based on the sequence stratigraphy and depositional facies interpretation of seismic profiles acquired by cruises of“China and Germany Joint Study on Marine Geosciences in the South China Sea”and“The formation,evolution and key issues of important resources in China marginal sea",and combining with ODP 1148 cole and LW33-1-1 well.The free-air gravity anomaly of the break up of the continental and ocean appears comparatively low negative anomaly traps which extended in EW,it is the reflection of passive margin gravitational effect.Bouguer gravity anomaly is comparatively low which is gradient zone extended NE-SW.Magnetic anomaly lies in Magnetic Quiet Zone at the Northern Continental Margin of the South China Sea.The Cenozoic sediments of lower continental slope in Southern Chaonan Sag can be divided into five stratum interface:SB5.5,SB10.5,SB16.5,SB23.8 and Hg,their ages are of Pliocene-Quaternary,late Miocene,middle Miocene,early Miocene,paleogene.The tectonic evolution of low continental slope depressions can be divided into rifting,rifting-depression transitional and depression stages,while their depositional environments change from river to shallow marine and abyssa1,which results in different topography in different stages.The topographic evolvement in the study

Dissolved inorganic carbon, pH, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using Alkalinity titrator, CTD and other instruments from MIRAI in the East China Sea, Japan Sea and others from 2005-10-31 to 2006-01-30 (NODC Accession 0109919)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0109919 includes chemical, discrete sample, physical and profile data collected from MIRAI in the East China Sea (Tung Hai), Japan Sea, North Pacific...

Dissolved inorganic carbon, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the KAIYO-MARU in the East China Sea (Tung Hai) and Philippine Sea from 1996-06-20 to 1996-07-15 (NODC Accession 0115023)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115023 includes chemical, discrete sample, physical and profile data collected from KAIYO-MARU in the East China Sea (Tung Hai) and Philippine Sea...

Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using Alkalinity titrator, CTD and other instruments from the G.O. SARS in the North Greenland Sea and Norwegian Sea from 2006-07-21 to 2006-08-05 (NODC Accession 0105859)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0105859 includes chemical, discrete sample, physical and profile data collected from G.O. SARS in the North Greenland Sea and Norwegian Sea from...

Temperature profile in apricot tree canopies under the soil and climate conditions of the Romanian Black Sea Coast

Science.gov (United States)

Paltineanu, Cristian; Septar, Leinar; Chitu, Emil

2016-03-01

The paper describes the temperature profiles determined by thermal imagery in apricot tree canopies under the semi-arid conditions of the Black Sea Coast in a chernozem of Dobrogea Region, Romania. The study analyzes the thermal vertical profile of apricot orchards for three representative cultivars during summertime. Measurements were done when the soil water content (SWC) was at field capacity (FC) within the rooting depth, after intense sprinkler irrigation applications. Canopy temperature was measured during clear sky days at three heights for both sides of the apricot trees, sunlit (south), and shaded (north). For the SWC studied, i.e., FC, canopy height did not induce a significant difference between the temperature of apricot tree leaves (Tc) and the ambient air temperature (Ta) within the entire vertical tree profile, and temperature measurements by thermal imagery can therefore be taken at any height on the tree crown leaves. Differences between sunlit and shaded sides of the canopy were significant. Because of these differences for Tc-Ta among the apricot tree cultivars studied, lower base lines (LBLs) should be determined for each cultivar separately. The use of thermal imagery technique under the conditions of semi-arid coastal areas with low range of vapor pressure deficit could be useful in irrigation scheduling of apricot trees. The paper discusses the implications of the data obtained in the experiment under the conditions of the coastal area of the Black Sea, Romania, and neighboring countries with similar climate, such as Bulgaria and Turkey.

Dissolved inorganic carbon, pH, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, Coulometer for DIC measurement and other instruments from MIRAI in the Beaufort Sea and Bering Sea from 2006-08-21 to 2006-09-29 (NODC Accession 0112268)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0112268 includes chemical, discrete sample, optical, physical and profile data collected from MIRAI in the Beaufort Sea and Bering Sea from 2006-08-21...

A global mean ocean circulation estimation using goce gravity models - the DTU12MDT mean dynamic topography model

DEFF Research Database (Denmark)

Knudsen, Per; Andersen, Ole Baltazar

2012-01-01

The Gravity and Ocean Circulation Experiment - GOCE satellite mission measure the Earth gravity field with unprecedented accuracy leading to substantial improvements in the modelling of the ocean circulation and transport. In this study of the performance of GOCE, a newer gravity model have been...... combined with the DTU10MSS mean sea surface model to construct a global mean dynamic topography model named DTU10MDT. The results of preliminary analyses using preliminary GOCE gravity models clearly demonstrated the potential of GOCE mission. Both the resolution and the estimation of the surface currents...... have been improved significantly compared to results obtained using pre-GOCE gravity field models. The results of this study show that geostrophic surface currents associated with the mean circulation have been further improved and that currents having speeds down to 5 cm/s have been recovered....

The Effect of Aerosol on Gravity Wave Characteristics above the Boundary Layer over a Tropical Location

Science.gov (United States)

Rakshit, G.; Jana, S.; Maitra, A.

2017-12-01

The perturbations of temperature profile over a location give an estimate of the potential energy of gravity waves propagating through the atmosphere. Disturbances in the lower atmosphere due to tropical deep convection, orographic effects and various atmospheric disturbances generates of gravity waves. The present study investigates the gravity wave energy estimated from fluctuations in temperature profiles over the tropical location Kolkata (22°34' N, 88°22' E). Gravity waves are most intense during the pre-monsoon period (March-June) at the present location, the potential energy having high values above the boundary layer (2-4 km) as observed from radiosonde profiles. An increase in temperature perturbation, due to high ambient temperature in the presence of heat absorbing aerosols, causes an enhancement in potential energy. As the present study location is an urban metropolitan city experiencing high level of pollution, pollutant aerosols can go much above the normal boundary layer during daytime due to convection causing an extended boundary layer. The Aerosol Index (AAI) obtained from Global Ozone Monitoring Experiment-2 (GOME-2) on MetOp-A platform at 340 nm and 380 nm confirms the presence of absorbing aerosol particles over the present location. The Hysplit back trajectory analysis shows that the aerosol particles at those heights are of local origin and are responsible for depleting liquid water content due to cloud burning. The aerosol extinction coefficient obtained from CALIPSO data exhibits an increasing trend during 2006-2016 accompanied by a similar pattern of gravity wave energy. Thus the absorbing aerosols have a significant role in increasing the potential energy of gravity wave at an urban location in the tropical region.

Miocene shale tectonics in the Moroccan margin (Alboran Sea)

Science.gov (United States)

Do Couto, D.; El Abbassi, M.; Ammar, A.; Gorini, C.; Estrada, F.; Letouzey, J.; Smit, J.; Jolivet, L.; Jabour, H.

2011-12-01

The Betic (Southern Spain) and Rif (Morocco) mountains form an arcuate belt that represents the westernmost termination of the peri-mediterranean Alpine mountain chain. The Miocene Alboran Basin and its subbasins is located in the hinterland of the Betic-Rif belt. It is considered to be a back-arc basin that developed during the coeval westward motion of the Alboran domain and the extensional collapse of previously thickened crust of the Betic-Rif belt. The Western Alboran Basin (WAB) is the major sedimentary depocenter with a sediment thickness in excess of 10 km, it is bordered by the Gibraltar arc, the volcanic Djibouti mounts and the Alboran ridge. Part of the WAB is affected by shale tectonics and associated mud volcanism. High-quality 2D seismic profiles acquired on the Moroccan margin of the Alboran Basin during the last decade reveal the multiple history of the basin. This study deals with the analysis of a number of these seismic profiles that are located along and orthogonal to the Moroccan margin. Seismic stratigraphy is calibrated from industrial wells. We focus on the interactions between the gravity-driven tectonic processes and the sedimentation in the basin. Our seismic interpretation confirms that the formation of the WAB began in the Early Miocene (Aquitanian - Burdigalian). The fast subsidence of the basin floor coeval to massive sedimentation induced the undercompaction of early miocene shales during their deposition. Downslope migration of these fine-grained sediments initiated during the deposition of the Langhian siliciclastics. This gravity-driven system was accompanied by continuous basement subsidence and induced disharmonic deformation in Mid Miocene units (i.e. not related to basement deformation). The development of shale-cored anticlines and thrusts in the deep basin is the result of compressive deformation at the front of the gravity-driven system and lasted for ca. 15 Ma. The compressive front has been re-activated by strong

Regulatory heterochronies and loose temporal scaling between sea star and sea urchin regulatory circuits.

Science.gov (United States)

Gildor, Tsvia; Hinman, Veronica; Ben-Tabou-De-Leon, Smadar

2017-01-01

It has long been argued that heterochrony, a change in relative timing of a developmental process, is a major source of evolutionary innovation. Heterochronic changes of regulatory gene activation could be the underlying molecular mechanism driving heterochronic changes through evolution. Here, we compare the temporal expression profiles of key regulatory circuits between sea urchin and sea star, representative of two classes of Echinoderms that shared a common ancestor about 500 million years ago. The morphologies of the sea urchin and sea star embryos are largely comparable, yet, differences in certain mesodermal cell types and ectodermal patterning result in distinct larval body plans. We generated high resolution temporal profiles of 17 mesodermally-, endodermally- and ectodermally-expressed regulatory genes in the sea star, Patiria miniata, and compared these to their orthologs in the Mediterranean sea urchin, Paracentrotus lividus. We found that the maternal to zygotic transition is delayed in the sea star compared to the sea urchin, in agreement with the longer cleavage stage in the sea star. Interestingly, the order of gene activation shows the highest variation in the relatively diverged mesodermal circuit, while the correlations of expression dynamics are the highest in the strongly conserved endodermal circuit. We detected loose scaling of the developmental rates of these species and observed interspecies heterochronies within all studied regulatory circuits. Thus, after 500 million years of parallel evolution, mild heterochronies between the species are frequently observed and the tight temporal scaling observed for closely related species no longer holds.

Dissolved inorganic carbon, pH, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using Alkalinity titrator, CTD and other instruments from JAKOV SMIRNITSKIY in the Beaufort Sea, East Siberian Sea and others from 2008-08-15 to 2008-09-16 (NODC Accession 0108368)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0108368 includes chemical, discrete sample, physical and profile data collected from JAKOV SMIRNITSKIY in the Beaufort Sea, East Siberian Sea, Kara...

Partial pressure (or fugacity) of carbon dioxide, dissolved inorganic carbon, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the USCGC POLAR SEA in the North Greenland Sea from 1993-07-18 to 1993-08-20 (NODC Accession 0114447)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0114447 includes biological, chemical, discrete sample, physical and profile data collected from USCGC POLAR SEA in the North Greenland Sea from...

Multi-scale mass movements: example of the Nile deep-sea fan (NDSF)

Science.gov (United States)

Loncke, L.; Droz, L.; Bellaiche, G.; Gaullier, V.; Mascle, J.; Migeon, S.

2003-04-01

The almost 90 000 km2 NDSF, fed by one of the major river in the world, has been nearly entirely surveyed by swath bathymetry and back-scatter imagery during the last four years. Seismic-reflection and 3-5 kHz profiles, and in some places, high resolution data were collected. Some profiles have been provided by BP-Egypt. Using this set of data, we have conducted a multi-scale regional synthesis which stresses the importance of gravity processes in the edification and evolution of this major deep turbidite system. Gravity processes range from regional gravity-driven spreading and gliding of the Plio-Pleistocene sediments above the Messinian mobile evaporites, to huge collapses of large areas of the upper continental slope as well as very localized levee destabilizations and related avulsion mechanisms. The Eastern - tectonized - area of the NDSF is characterized by lens-shaped transparent bodies, likely indicating debris-flow deposits, settled at crestal graben flanks, themselves generated by reactive diapir rise. Debris flows are probably triggered by local readjustments of salt-related tectonic features destabilizing their sedimentary cover. In contrast, within the poorly deformed Western part of the NDSF, we mainly observe recent slumping and gliding phenomenons, incising the upper slope where salt layers are absent. These slumps and glidings evolved downslope to large debris flows. Some of them exhibit volumes up to 1900 km3 and are covered by recent stacked channel-levees units. Smaller scale debris-flows are inter-fingered within these constructional units and led to numerous channel migrations and avulsions, characterized by typical HARP's seismic facies. Recent sedimentary destabilizations seem to be associated with gas seeping or under-compacted mud ascents: in the Central NDSF, the association between pock-marks (or mounds) and destabilizated masses suggest the existence of gas hydrates. Given the variety of processes (either triggered by tectonics

Gravity Terrain Effect of the Seafloor Topography in Taiwan

Directory of Open Access Journals (Sweden)

Lun-Tao Tong Tai-Rong Guo

2007-01-01

Full Text Available Gravity terrain correction is used to compensate for the gravitational effects of the topography residual to the Bouguer plate. The seafloor topography off the eastern offshore of Taiwan is extremely rugged, and the depth of the sea bottom could be greater than 5000 m. In order to evaluate the terrain effect caused by the seafloor topography, a modern computer algorithm is used to calculate the terrain correction based on the digital elevation model (DEM.

Even-dimensional topological gravity from Chern-Simons gravity

International Nuclear Information System (INIS)

Merino, N.; Perez, A.; Salgado, P.

2009-01-01

It is shown that the topological action for gravity in 2n-dimensions can be obtained from the (2n+1)-dimensional Chern-Simons gravity genuinely invariant under the Poincare group. The 2n-dimensional topological gravity is described by the dynamics of the boundary of a (2n+1)-dimensional Chern-Simons gravity theory with suitable boundary conditions. The field φ a , which is necessary to construct this type of topological gravity in even dimensions, is identified with the coset field associated with the non-linear realizations of the Poincare group ISO(d-1,1).

PFAS profiles in three North Sea top predators: metabolic differences among species?

Science.gov (United States)

Galatius, Anders; Bossi, Rossana; Sonne, Christian; Rigét, Frank Farsø; Kinze, Carl Christian; Lockyer, Christina; Teilmann, Jonas; Dietz, Rune

2013-11-01

Profiles of seven compounds of perfluoro-alkyl substances (PFASs) were compared among three species of top predators from the Danish North Sea: the white-beaked dolphin (Lagenorhynchus albirostris), the harbor porpoise (Phocoena phocoena), and the harbor seal (Phoca vitulina). The seals had higher total burdens (757.8 ng g(-1) ww) than the dolphins (439.9 ng g(-1) ww) and the porpoises (355.8 ng g(-1) ww), probably a reflection of feeding closer to the shore and thus contamination sources. The most striking difference among the species was the relative contribution of perfluorooctanesulfonamide (PFOSA) to the profiles; the seals (0.1%) had much lower levels than porpoises (8.3%) and dolphins (26.0%). In combination with the values obtained from the literature, this result indicates that Carnivora species including Pinnipedia have a much higher capacity of transforming PFOSA to perfluorooctane sulfonic acid (PFOS) than cetacean species. Another notable difference among the species was that the two smaller species (seals and porpoises) with supposedly higher metabolic rates had lower concentrations of the perfluorinated carboxylic acids, which are generally more easily excreted than perfluorinated sulfonamides. Species-specific characteristics should be recognized when PFAS contamination in marine mammals is investigated, for example, several previous studies of PFASs in cetaceans have not quantified PFOSA.

Temperature, salinity, nutrient, and ammonia profiles collected by bottle in the Black Sea from 5/5/1955 - 4/16/1989 (NODC Accession 0000131)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Nutrients and temperature profile data were collected using bottle casts from the FIOLENT and other platforms in the Black Sea. Data were collected from 05 May 1955...

High-resolution gravity and seismic-refraction surveys of the Smoke Tree Wash area, Joshua Tree National Park, California

Science.gov (United States)

Langenheim, Victoria E.; Rymer, Michael J.; Catchings, Rufus D.; Goldman, Mark R.; Watt, Janet T.; Powell, Robert E.; Matti, Jonathan C.

2016-03-02

We describe high-resolution gravity and seismic refraction surveys acquired to determine the thickness of valley-fill deposits and to delineate geologic structures that might influence groundwater flow beneath the Smoke Tree Wash area in Joshua Tree National Park. These surveys identified a sedimentary basin that is fault-controlled. A profile across the Smoke Tree Wash fault zone reveals low gravity values and seismic velocities that coincide with a mapped strand of the Smoke Tree Wash fault. Modeling of the gravity data reveals a basin about 2–2.5 km long and 1 km wide that is roughly centered on this mapped strand, and bounded by inferred faults. According to the gravity model the deepest part of the basin is about 270 m, but this area coincides with low velocities that are not characteristic of typical basement complex rocks. Most likely, the density contrast assumed in the inversion is too high or the uncharacteristically low velocities represent highly fractured or weathered basement rocks, or both. A longer seismic profile extending onto basement outcrops would help differentiate which scenario is more accurate. The seismic velocities also determine the depth to water table along the profile to be about 40–60 m, consistent with water levels measured in water wells near the northern end of the profile.

Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, Coulometer for DIC measurement and other instruments from the MIRAI in the Arctic Ocean, Beaufort Sea and Bering Sea from 2000-08-03 to 2000-10-13 (NODC Accession 0112352)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0112352 includes chemical, discrete sample, physical and profile data collected from MIRAI in the Arctic Ocean, Beaufort Sea and Bering Sea from...

Mass-induced sea level variations in the Red Sea from steric-corrected altimetry, GRACE, in-situ bottom pressure records, and hydrographic observations

Science.gov (United States)

Feng, Wei; Lemoine, Jean-Michel; Zhong, Min; Xu, Houze

2014-05-01

An annual amplitude of ~18 cm mass-induced sea level variations (SLV) in the Red Sea is detected from steric-corrected altimetry and the Gravity Recovery and Climate Experiment (GRACE) satellites from 2003 to 2011, which dominates the mean sea level in the region. Seawater mass variations here generally reach maximum in late January/early February. The steric component of SLV calculated from oceanographic temperature and salinity data is relatively small and peaks about seven months later than mass variations. The phase difference between the steric SLV and the mass-induced SLV indicates that when the Red Sea gains the mass from inflow water in winter, the steric SLV fall, and vice versa in summer. In-situ bottom pressure records in the eastern coast of the Red Sea validate the high mass variability observed by steric-corrected altimetry and GRACE. Furthermore, we compare the horizontal water mass flux in the Red Sea from steric-corrected altimetry and GRACE with that estimated from hydrographic observations.

Persistent organic pollutants in ringed seals from the Russian Arctic.

Science.gov (United States)

Savinov, Vladimir; Muir, Derek C G; Svetochev, Vladislav; Svetocheva, Olga; Belikov, Stanislav; Boltunov, Andrey; Alekseeva, Ludmila; Reiersen, Lars-Otto; Savinova, Tatiana

2011-06-15

Organochlorine compounds total DDT (ΣDDT), total HCH isomers (ΣHCH), toxaphenes (sum of Parlar 26, 50, 62), mirex, endrin, methoxychlor, total chlorinated benzenes (ΣCBz), total chlordane compounds (ΣCHL), polychlorinated biphenyls (total of 56 congeners; ΣPCBs), polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), and polybrominated diphenyl ethers (sum of 7 tri- to hepta congeners; ΣPBDEs) were analysed in the blubber of adult ringed seals from the four areas of the Russian Arctic (White Sea, Barents Sea, Kara Sea and Chukchi Sea) collected in 2001-2005. Ringed seals from the south-western part of the Kara Sea (Dikson Island - Yenisei estuary) were the most contaminated with ΣDDTs, ΣPCBs, ΣCHL, and mirex as compared with those found in the other three areas of Russian Arctic, while the highest mean concentrations of ΣHCHs and PCDD/Fs were found in the blubber of ringed seals from the Chukchi Sea and the White Sea, respectively. Among all organochlorine compounds measured in ringed seals from the European part of the Russian Arctic, concentrations of ΣDDT and ΣPCBs only were higher as compared with the other Arctic regions. Levels of all other organochlorine compounds were similar or lower than in seals from Svalbard, Alaska, the Canadian Arctic and Greenland. ΣPBDEs were found in all ringed seal samples analysed. There were no significant differences between ΣPBDE concentrations found in the blubber of ringed seals from the three studied areas of the European part of the Russian Arctic, while PBDE contamination level in ringed seals from the Chukchi Sea was 30-50 times lower. ΣPBDE levels in the blubber of seals from the European part of the Russian Arctic are slightly higher than in ringed seals from the Canadian Arctic, Alaska, and western Greenland but lower compared to ringed seals from Svalbard and eastern Greenland. Copyright © 2011 Elsevier B.V. All rights reserved.

Polar gravity fields from GOCE and airborne gravity

DEFF Research Database (Denmark)

Forsberg, René; Olesen, Arne Vestergaard; Yidiz, Hasan

2011-01-01

Airborne gravity, together with high-quality surface data and ocean satellite altimetric gravity, may supplement GOCE to make consistent, accurate high resolution global gravity field models. In the polar regions, the special challenge of the GOCE polar gap make the error characteristics...... of combination models especially sensitive to the correct merging of satellite and surface data. We outline comparisons of GOCE to recent airborne gravity surveys in both the Arctic and the Antarctic. The comparison is done to new 8-month GOCE solutions, as well as to a collocation prediction from GOCE gradients...... in Antarctica. It is shown how the enhanced gravity field solutions improve the determination of ocean dynamic topography in both the Arctic and in across the Drake Passage. For the interior of Antarctica, major airborne gravity programs are currently being carried out, and there is an urgent need...

The effect of sediment loading in Fennoscandia and the Barents Sea during the last glacial cycle on glacial isostatic adjustment observations

Directory of Open Access Journals (Sweden)

W. van der Wal

2017-09-01

Full Text Available Models for glacial isostatic adjustment (GIA routinely include the effects of meltwater redistribution and changes in topography and coastlines. Since the sediment transport related to the dynamics of ice sheets may be comparable to that of sea level rise in terms of surface pressure, the loading effect of sediment deposition could cause measurable ongoing viscous readjustment. Here, we study the loading effect of glacially induced sediment redistribution (GISR related to the Weichselian ice sheet in Fennoscandia and the Barents Sea. The surface loading effect and its effect on the gravitational potential is modeled by including changes in sediment thickness in the sea level equation following the method of Dalca et al. (2013. Sediment displacement estimates are estimated in two different ways: (i from a compilation of studies on local features (trough mouth fans, large-scale failures, and basin flux and (ii from output of a coupled ice–sediment model. To account for uncertainty in Earth's rheology, three viscosity profiles are used. It is found that sediment transport can lead to changes in relative sea level of up to 2 m in the last 6000 years and larger effects occurring earlier in the deglaciation. This magnitude is below the error level of most of the relative sea level data because those data are sparse and errors increase with length of time before present. The effect on present-day uplift rates reaches a few tenths of millimeters per year in large parts of Norway and Sweden, which is around the measurement error of long-term GNSS (global navigation satellite system monitoring networks. The maximum effect on present-day gravity rates as measured by the GRACE (Gravity Recovery and Climate Experiment satellite mission is up to tenths of microgal per year, which is larger than the measurement error but below other error sources. Since GISR causes systematic uplift in most of mainland Scandinavia, including GISR in GIA models

Late Jurassic – early Cretaceous inversion of rift structures, and linkage of petroleum system elements across post-rift unconformity, U.S. Chukchi Shelf, arctic Alaska

Science.gov (United States)

Houseknecht, David W.; Connors, Christopher D.

2015-01-01

Basin evolution of the U.S. Chukchi shelf involved multiple phases, including Late Devonian–Permian rifting, Permian–Early Jurassic sagging, Late Jurassic–Neocomian inversion, and Cretaceous–Cenozoic foreland-basin development. The focus of ongoing exploration is a petroleum system that includes sag-phase source rocks; inversion-phase reservoir rocks; structure spanning the rift, sag, and inversion phases; and hydrocarbon generation during the foreland-basin phase.

Increased Arctic sea ice drift alters adult female polar bear movements and energetics.

Science.gov (United States)

Durner, George M; Douglas, David C; Albeke, Shannon E; Whiteman, John P; Amstrup, Steven C; Richardson, Evan; Wilson, Ryan R; Ben-David, Merav

2017-09-01

Recent reductions in thickness and extent have increased drift rates of Arctic sea ice. Increased ice drift could significantly affect the movements and the energy balance of polar bears (Ursus maritimus) which forage, nearly exclusively, on this substrate. We used radio-tracking and ice drift data to quantify the influence of increased drift on bear movements, and we modeled the consequences for energy demands of adult females in the Beaufort and Chukchi seas during two periods with different sea ice characteristics. Westward and northward drift of the sea ice used by polar bears in both regions increased between 1987-1998 and 1999-2013. To remain within their home ranges, polar bears responded to the higher westward ice drift with greater eastward movements, while their movements north in the spring and south in fall were frequently aided by ice motion. To compensate for more rapid westward ice drift in recent years, polar bears covered greater daily distances either by increasing their time spent active (7.6%-9.6%) or by increasing their travel speed (8.5%-8.9%). This increased their calculated annual energy expenditure by 1.8%-3.6% (depending on region and reproductive status), a cost that could be met by capturing an additional 1-3 seals/year. Polar bears selected similar habitats in both periods, indicating that faster drift did not alter habitat preferences. Compounding reduced foraging opportunities that result from habitat loss; changes in ice drift, and associated activity increases, likely exacerbate the physiological stress experienced by polar bears in a warming Arctic. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

The nepheloid bottom layer and water masses at the shelf break of the western Ross Sea

Science.gov (United States)

Capello, Marco; Budillon, Giorgio; Cutroneo, Laura; Tucci, Sergio

2009-06-01

In the austral summers of 2000/2001 and 2002/2003 the Italian CLIMA Project carried out two oceanographic cruises along the northwestern margin of the Ross Sea, where the Antarctic Bottom Water forms. Here there is an interaction between the water masses on the sea floor of the outer shelf and slope with a consequent evolution of benthic nepheloid layers and an increase in total particulate matter. We observed three different situations: (a) the presence of triads (bottom structures characterized by a concomitant jump in turbidity, temperature, and salinity data) and high re-suspension phenomena related to the presence of the Circumpolar Deep Water and its mixing with cold, salty shelf waters associated with gravity currents; (b) the absence of triads with high re-suspension, implying that when the gravity currents are no longer active the benthic nepheloid layer may persist until the suspended particles settle to the sea floor, suggesting that the turbidity data can be used to study recent gravity current events; and (c) the absence of turbidity and sediment re-suspension phenomena supports the theory that a steady situation had been re-established and the current interaction no longer occurred or had finished sometime before.

A perturbative approach to neutron stars in f(T, T)-gravity

Energy Technology Data Exchange (ETDEWEB)

Pace, Mark; Said, Jackson Levi [University of Malta, Department of Physics, Msida (Malta); University of Malta, Institute of Space Sciences and Astronomy, Msida (Malta)

2017-05-15

We derive a Tolman-Oppenheimer-Volkoff equation in neutron star systems within the modified f(T, T)-gravity class of models using a perturbative approach. In our approach f(T, T)-gravity is considered to be a static spherically symmetric space-time. In this instance the metric is built from a more fundamental vierbein which can be used to relate inertial and global coordinates. A linear function f = T(r) + T(r) + χh(T, T) + O(χ{sup 2}) is taken as the Lagrangian density for the gravitational action. Finally we impose the polytropic equation of state of neutron star upon the derived equations in order to derive the mass profile and mass-central density relations of the neutron star in f(T, T)-gravity. (orig.)

Can representational trajectory reveal the nature of an internal model of gravity?

Science.gov (United States)

De Sá Teixeira, Nuno; Hecht, Heiko

2014-05-01

The memory for the vanishing location of a horizontally moving target is usually displaced forward in the direction of motion (representational momentum) and downward in the direction of gravity (representational gravity). Moreover, this downward displacement has been shown to increase with time (representational trajectory). However, the degree to which different kinematic events change the temporal profile of these displacements remains to be determined. The present article attempts to fill this gap. In the first experiment, we replicate the finding that representational momentum for downward-moving targets is bigger than for upward motions, showing, moreover, that it increases rapidly during the first 300 ms, stabilizing afterward. This temporal profile, but not the increased error for descending targets, is shown to be disrupted when eye movements are not allowed. In the second experiment, we show that the downward drift with time emerges even for static targets. Finally, in the third experiment, we report an increased error for upward-moving targets, as compared with downward movements, when the display is compatible with a downward ego-motion by including vection cues. Thus, the errors in the direction of gravity are compatible with the perceived event and do not merely reflect a retinotopic bias. Overall, these results provide further evidence for an internal model of gravity in the visual representational system.

Seasonal variation of deep-sea bioluminescence in the Ionian Sea

International Nuclear Information System (INIS)

Craig, Jessica; Jamieson, Alan J.; Bagley, Philip M.; Priede, Imants G.

2011-01-01

The ICDeep (Image Intensified Charge Coupled Device for Deep sea research) profiler was used to measure the density of deep bioluminescent animals (BL) through the water column in the east, west and mid-Ionian Sea and in the Algerian Basin. A west to east decrease in BL density was found. Generalized additive modelling was used to investigate seasonal variation in the east and west Ionian Sea (NESTOR and NEMO neutrino telescope sites, respectively) from BL measurements in autumn 2008 and spring 2009. A significant seasonal effect was found in the west Ionian Sea (p<0.001), where a deep autumnal peak in BL density occurred between 500 and 2400 m. No significant seasonal variation in BL density was found in the east Ionian Sea (p=0.07). In both spring and autumn, significant differences in BL density were found through the water column between the east and west Ionian Sea (p<0.001).

Seasonal variation of deep-sea bioluminescence in the Ionian Sea

Energy Technology Data Exchange (ETDEWEB)

Craig, Jessica, E-mail: j.craig@abdn.ac.u [University of Aberdeen, Oceanlab, Main Street, Newburgh, Aberdeenshire, AB41 6AA (United Kingdom); Jamieson, Alan J.; Bagley, Philip M.; Priede, Imants G. [University of Aberdeen, Oceanlab, Main Street, Newburgh, Aberdeenshire, AB41 6AA (United Kingdom)

2011-01-21

The ICDeep (Image Intensified Charge Coupled Device for Deep sea research) profiler was used to measure the density of deep bioluminescent animals (BL) through the water column in the east, west and mid-Ionian Sea and in the Algerian Basin. A west to east decrease in BL density was found. Generalized additive modelling was used to investigate seasonal variation in the east and west Ionian Sea (NESTOR and NEMO neutrino telescope sites, respectively) from BL measurements in autumn 2008 and spring 2009. A significant seasonal effect was found in the west Ionian Sea (p<0.001), where a deep autumnal peak in BL density occurred between 500 and 2400 m. No significant seasonal variation in BL density was found in the east Ionian Sea (p=0.07). In both spring and autumn, significant differences in BL density were found through the water column between the east and west Ionian Sea (p<0.001).

Estimating age ratios and size of pacific walrus herds on coastal haulouts using video imaging.

Directory of Open Access Journals (Sweden)

Daniel H Monson

Full Text Available During Arctic summers, sea ice provides resting habitat for Pacific walruses as it drifts over foraging areas in the eastern Chukchi Sea. Climate-driven reductions in sea ice have recently created ice-free conditions in the Chukchi Sea by late summer causing walruses to rest at coastal haulouts along the Chukotka and Alaska coasts, which provides an opportunity to study walruses at relatively accessible locations. Walrus age can be determined from the ratio of tusk length to snout dimensions. We evaluated use of images obtained from a gyro-stabilized video system mounted on a helicopter flying at high altitudes (to avoid disturbance to classify the sex and age of walruses hauled out on Alaska beaches in 2010-2011. We were able to classify 95% of randomly selected individuals to either an 8- or 3-category age class, and we found measurement-based age classifications were more repeatable than visual classifications when using images presenting the correct head profile. Herd density at coastal haulouts averaged 0.88 walruses/m(2 (std. err. = 0.02, herd size ranged from 8,300 to 19,400 (CV 0.03-0.06 and we documented ∼30,000 animals along ∼1 km of beach in 2011. Within the herds, dependent walruses (0-2 yr-olds tended to be located closer to water, and this tendency became more pronounced as the herd spent more time on the beach. Therefore, unbiased estimation of herd age-ratios will require a sampling design that allows for spatial and temporal structuring. In addition, randomly sampling walruses available at the edge of the herd for other purposes (e.g., tagging, biopsying will not sample walruses with an age structure representative of the herd. Sea ice losses are projected to continue, and population age structure data collected with aerial videography at coastal haulouts may provide demographic information vital to ongoing efforts to understand effects of climate change on this species.

Geographical distribution of organochlorine pesticides (OCPs) in polar bears (Ursus maritimus) in the Norwegian and Russian Arctic

Science.gov (United States)

Lie, E.; Bernhoft, A.; Riget, F.; Belikov, Stanislav; Boltunov, Andrei N.; Derocher, A.E.; Garner, G.W.; Wiig, O.; Skaare, J.U.

2003-01-01

Geographical variation of organochlorine pesticides (OCPs) was studied in blood samples from 90 adult female polar bear (Ursus maritimus) from Svalbard, Franz Josef Land, Kara Sea, East-Siberian Sea and Chukchi Sea. In all regions, oxychlordane was the dominant OCP. Regional differences in mean levels of HCB, oxychlordane, trans-nonachlor, ??-HCH, ??-HCH and p,p???-DDE were found. The highest levels of oxychlordane, trans-nonachlor and DDE were found in polar bears from Franz Josef Land and Kara Sea. HCB level was lowest in polar bears from Svalbard. Polar bears from Chukchi Sea had the highest level of ??- and ??-HCH. The lowest ??-HCH concentration was found in bears from Kara Sea. In all the bears, ???HCHs was dominated by ??-HCH. The geographical variation in OCP levels and pattern may suggest regional differences in pollution sources and different feeding habits in the different regions. Polar bears from the Western Russian Arctic were exposed to higher levels of chlordanes and p,p???-DDE than polar bears from locations westwards and eastwards from this region. This may imply the presence of a significant pollution source in the Russian Arctic area. The study suggests that the western Russian Arctic is the most contaminated region of the Arctic and warrants further research. ?? 2002 Elsevier Science B.V. All rights reserved.

Comparison of satellite altimetry sea level anomalies and hydrographic observations in the Mediterranean Sea

Directory of Open Access Journals (Sweden)

Francisco Mir Calafat

2012-08-01

Full Text Available Steric sea level (SSL computed from hydrographic observations in the Mediterranean Sea is compared against altimetric sea level anomalies (SLA at seasonal and inter-annual time scales for the period 1993-2008. SSL (referenced to 300 m is computed using two data sets: in situ profiles and gridded products obtained from interpolated observations. The impact of expendable/mechanical bathythermograph (XBT/MBT biases affecting some of the in situ profiles is investigated by comparing both corrected and uncorrected data. For the period 2003-2008 the mass component is estimated from GRACE observations and subtracted from SLA. The analysis of the spatio-temporal distribution of profiles shows that the number of profiles with data below 300 m is a small percentage of the total and that their spatial coverage of the Mediterranean basin is very limited. This is an important handicap for regions where the contribution of the deep layers to SSL is significant. Overall, SSL and SLA are shown to be consistent in the Mediterranean at seasonal time scales, although the annual amplitude of the SSL from in situ profiles and interpolated data is considerably smaller than that of the SLA. The agreement at inter-annual time scales is less good. At some particular locations SSL computed from individual profiles is more correlated with SLA than the gridded products. At basin and sub-basin scales, however, interpolated and in situ observations provide similar results in terms of their correlation with observed SLA. The XBT/MBT bias corrections have little effect on the SSL at the time scales considered in this study.

Simulation of an oil film at the sea surface and its radiometric properties in the SWIR

Science.gov (United States)

Schwenger, Frédéric; Van Eijk, Alexander M. J.

2017-10-01

The knowledge of the optical contrast of an oil layer on the sea under various surface roughness conditions is of great interest for oil slick monitoring techniques. This paper presents a 3D simulation of a dynamic sea surface contaminated by a floating oil film. The simulation considers the damping influence of oil on the ocean waves and its physical properties. It calculates the radiance contrast of the sea surface polluted by the oil film in relation to a clean sea surface for the SWIR spectral band. Our computer simulation combines the 3D simulation of a maritime scene (open clear sea/clear sky) with an oil film at the sea surface. The basic geometry of a clean sea surface is modeled by a composition of smooth wind driven gravity waves. Oil on the sea surface attenuates the capillary and short gravity waves modulating the wave power density spectrum of these waves. The radiance of the maritime scene is calculated in the SWIR spectral band with the emitted sea surface radiance and the specularly reflected sky radiance as components. Wave hiding and shadowing, especially occurring at low viewing angles, are considered. The specular reflection of the sky radiance at the clean sea surface is modeled by an analytical statistical bidirectional reflectance distribution function (BRDF) of the sea surface. For oil at the sea surface, a specific BRDF is used influenced by the reduced surface roughness, i.e., the modulated wave density spectrum. The radiance contrast of an oil film in relation to the clean sea surface is calculated for different viewing angles, wind speeds, and oil types characterized by their specific physical properties.

Dissolved inorganic carbon, pH, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, Coulometer for DIC measurement and other instruments from the ODEN in the Arctic Ocean, Beaufort Sea and Bering Sea from 2005-08-19 to 2005-09-25 (NODC Accession 0108129)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0108129 includes chemical, discrete sample, physical and profile data collected from ODEN in the Arctic Ocean, Beaufort Sea and Bering Sea from...

Gravity-dependent ventilation distribution in rats measured with electrical impedance tomography

International Nuclear Information System (INIS)

Rooney, Daniel; Fraser, John F; R Dunster, Kimble; Schibler, Andreas; Friese, Marlies

2009-01-01

Ventilation in larger animals and humans is gravity dependent and mainly distributed to the dependent lung. Little is known of the effect of gravity on ventilation distribution in small animals such as rodents. The aim of this study was to investigate gravity-dependent ventilation distribution and regional filling characteristics in rats. Ventilation distribution and regional lung filling were measured in six rats using electrical impedance tomography (EIT). Measurements were performed in four body positions (supine, prone, left and right lateral), and all animals were ventilated with increasing tidal volumes from 3 to 8 mL kg −1 . The effect of gravity on regional ventilation distribution was assessed with profiles of relative impedance change and calculation of the geometric centre. Regional filling was measured by calculating the slope of the plot of regional versus global relative impedance change on a breath-by-breath basis. Ventilation was significantly distributed to the non-dependent lung regardless of body position and tidal volume used. The geometric centre was located in the dependent lung in all but prone position. The regional filling characteristics followed an anatomical pattern with the posterior and the right lung generally filling faster. Gravity had little impact on regional filling. Ventilation distribution in rats is gravity dependent, whereas regional filling characteristics are dependent on anatomy

Metagenomic analysis and metabolite profiling of deep-sea sediments from the Gulf of Mexico following the Deepwater Horizon oil spill

Directory of Open Access Journals (Sweden)

Nikole Elizabeth Kimes

2013-03-01

Full Text Available Marine subsurface environments, such as deep-sea sediments, house abundant and diverse microbial communities that are believed to influence large-scale geochemical processes. These processes include the biotransformation and mineralization of numerous petroleum constituents. Thus, microbial communities in the Gulf of Mexico are thought to be responsible for the intrinsic bioremediation of crude oil released by the Deepwater Horizon (DWH oil spill. While hydrocarbon contamination is known to enrich for aerobic, oil-degrading bacteria in deep-seawater habitats, relatively little is known about the response of communities in deep-sea sediments, where low oxygen levels may hinder such a response. Here, we examined the hypothesis that increased hydrocarbon exposure results in an altered sediment microbial community structure that reflects the prospects for oil biodegradation under the prevailing conditions. We explore this hypothesis using metagenomic analysis and metabolite profiling of deep-sea sediment samples following the DWH oil spill. The presence of aerobic microbial communities and associated functional genes was consistent among all samples, whereas, a greater number of Deltaproteobacteria and anaerobic functional genes were found in sediments closest to the DWH blowout site. Metabolite profiling also revealed a greater number of putative metabolites in sediments surrounding the blowout zone relative to a background site located 127 km away. The mass spectral analysis of the putative metabolites revealed that alkylsuccinates remained below detection levels, but a homologous series of benzylsuccinates (with carbon chain lengths from 5 to 10 could be detected. Our findings suggest that increased exposure to hydrocarbons enriches for Deltaproteobacteria, which are known to be capable of anaerobic hydrocarbon metabolism. We also provide evidence for an active microbial community metabolizing aromatic hydrocarbons in deep-sea sediments of the

Total body irradiation with an arc and a gravity-oriented compensator

International Nuclear Information System (INIS)

Chui, C.-S.; Fontenla, Doracy P.; Mullokandov, Edward; Kapulsky, Alex; Lo, Y.-C.; Lo, C.-J.

1997-01-01

Purpose: To deliver uniform dose distributions for total-body irradiation (TBI) with an arc field and a gravity-oriented compensator. This technique allows the patient to be treated lying on the floor in a small treatment room. Methods and Materials: Through the sweeping motion of the gantry, a continuous arc field can deliver a large field to a patient lying on the floor. The dose profile, however, would not be uniform if no compensator were used, due to the effects of inverse square variation of beam intensity with distance as well as the slanted depth in patient. To solve this problem, a gravity-oriented compensator made of cerrobend alloy was designed. This compensator has a cross-section of an inverted isosceles triangle, with the apex always pointing downward, due to gravity. By properly selecting the thickness of the compensator, the width of the base, and the distance between the pivots to the base, the difference in the path length through the compensator can be made just right to compensate the effects of inverse-square and slanted depth, thus producing a uniform dose profile. Results: Arc fields with a gravity-oriented compensator were used for 6, 10, 15, and 18 MV photon beams. The arc field can cover a patient with a height up to 180 cm. The field width was chosen from 32 to 40 cm at the machine isocenter. The optimal thickness of the compensator was found to be 2.5 cm, and its base was 25 cm wide. The distance from the pivot points to the flat surface of the compensator proximal to the beam ranges from 13 to 14 cm for different beam energies. The dose uniformity at a depth of 10 cm is within ±5% for all beam energies used in this study. Conclusion: Highly uniform dose profiles for TBI treatments can be delivered with an arc and a gravity-oriented compensator. The proposed technique is simple and versatile. A single compensator can be used for all energies, because the amount of compensation can be adjusted by changing the distance to the pivot and

Thinned crustal structure and tectonic boundary of the Nansha Block, southern South China Sea

Science.gov (United States)

Dong, Miao; Wu, Shi-Guo; Zhang, Jian

2016-12-01

The southern South China Sea margin consists of the thinned crustal Nansha Block and a compressional collision zone. The Nansha Block's deep structure and tectonic evolution contains critical information about the South China Sea's rifting. Multiple geophysical data sets, including regional magnetic, gravity and reflection seismic data, reveal the deep structure and rifting processes. Curie point depth (CPD), estimated from magnetic anomalies using a windowed wavenumber-domain algorithm, enables us to image thermal structures. To derive a 3D Moho topography and crustal thickness model, we apply Oldenburg algorithm to the gravity anomaly, which was extracted from the observed free air gravity anomaly data after removing the gravity effect of density variations of sediments, and temperature and pressure variations of the lithospheric mantle. We found that the Moho depth (20 km) is shallower than the CPD (24 km) in the Northwest Borneo Trough, possibly caused by thinned crust, low heat flow and a low vertical geothermal gradient. The Nansha Block's northern boundary is a narrow continent-ocean transition zone constrained by magnetic anomalies, reflection seismic data, gravity anomalies and an interpretation of Moho depth (about 13 km). The block extends southward beneath a gravity-driven deformed sediment wedge caused by uplift on land after a collision, with a contribution from deep crustal flow. Its southwestern boundary is close to the Lupar Line defined by a significant negative reduction to the pole (RTP) of magnetic anomaly and short-length-scale variation in crustal thickness, increasing from 18 to 26 km.

Dissolved inorganic carbon, pH, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, Coulometer for DIC measurement and other instruments from MIRAI in the Japan Sea, North Pacific Ocean and Sea of Okhotsk from 2006-08-01 to 2006-08-20 (NODC Accession 0112267)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0112267 includes chemical, discrete sample, optical, physical and profile data collected from MIRAI in the Japan Sea, North Pacific Ocean and Sea of...

Massive Gravity

OpenAIRE

de Rham, Claudia

2014-01-01

We review recent progress in massive gravity. We start by showing how different theories of massive gravity emerge from a higher-dimensional theory of general relativity, leading to the Dvali–Gabadadze–Porrati model (DGP), cascading gravity, and ghost-free massive gravity. We then explore their theoretical and phenomenological consistency, proving the absence of Boulware–Deser ghosts and reviewing the Vainshtein mechanism and the cosmological solutions in these models. Finally, we present alt...

Large-scale identification and comparative analysis of miRNA expression profile in the respiratory tree of the sea cucumber Apostichopus japonicus during aestivation.

Science.gov (United States)

Chen, Muyan; Storey, Kenneth B

2014-02-01

The sea cucumber Apostichopus japonicus withstands high water temperatures in the summer by suppressing its metabolic rate and entering a state of aestivation. We hypothesized that changes in the expression of miRNAs could provide important post-transcriptional regulation of gene expression during hypometabolism via control over mRNA translation. The present study analyzed profiles of miRNA expression in the sea cucumber respiratory tree using Solexa deep sequencing technology. We identified 279 sea cucumber miRNAs, including 15 novel miRNAs specific to sea cucumber. Animals sampled during deep aestivation (DA; after at least 15 days of continuous torpor) were compared with animals from a non-aestivation (NA) state (animals that had passed through aestivation and returned to an active state). We identified 30 differentially expressed miRNAs ([RPM (reads per million) >10, |FC| (|fold change|)≥1, FDR (false discovery rate)<0.01]) during aestivation, which were validated by two other miRNA profiling methods: miRNA microarray and real-time PCR. Among the most prominent miRNA species, miR-124, miR-124-3p, miR-79, miR-9 and miR-2010 were significantly over-expressed during deep aestivation compared with non-aestivation animals, suggesting that these miRNAs may play important roles in metabolic rate suppression during aestivation. High-throughput sequencing data and microarray data have been submitted to the GEO database with accession number: 16902695. Copyright © 2014 Elsevier B.V. All rights reserved.

Acoustic-gravity waves in atmospheric and oceanic waveguides.

Science.gov (United States)

Godin, Oleg A

2012-08-01

A theory of guided propagation of sound in layered, moving fluids is extended to include acoustic-gravity waves (AGWs) in waveguides with piecewise continuous parameters. The orthogonality of AGW normal modes is established in moving and motionless media. A perturbation theory is developed to quantify the relative significance of the gravity and fluid compressibility as well as sensitivity of the normal modes to variations in sound speed, flow velocity, and density profiles and in boundary conditions. Phase and group speeds of the normal modes are found to have certain universal properties which are valid for waveguides with arbitrary stratification. The Lamb wave is shown to be the only AGW normal mode that can propagate without dispersion in a layered medium.

Gravity Compensation Using EGM2008 for High-Precision Long-Term Inertial Navigation Systems

Directory of Open Access Journals (Sweden)

Ruonan Wu

2016-12-01

Full Text Available The gravity disturbance vector is one of the major error sources in high-precision and long-term inertial navigation applications. Specific to the inertial navigation systems (INSs with high-order horizontal damping networks, analyses of the error propagation show that the gravity-induced errors exist almost exclusively in the horizontal channels and are mostly caused by deflections of the vertical (DOV. Low-frequency components of the DOV propagate into the latitude and longitude errors at a ratio of 1:1 and time-varying fluctuations in the DOV excite Schuler oscillation. This paper presents two gravity compensation methods using the Earth Gravitational Model 2008 (EGM2008, namely, interpolation from the off-line database and computing gravity vectors directly using the spherical harmonic model. Particular attention is given to the error contribution of the gravity update interval and computing time delay. It is recommended for the marine navigation that a gravity vector should be calculated within 1 s and updated every 100 s at most. To meet this demand, the time duration of calculating the current gravity vector using EGM2008 has been reduced to less than 1 s by optimizing the calculation procedure. A few off-line experiments were conducted using the data of a shipborne INS collected during an actual sea test. With the aid of EGM2008, most of the low-frequency components of the position errors caused by the gravity disturbance vector have been removed and the Schuler oscillation has been attenuated effectively. In the rugged terrain, the horizontal position error could be reduced at best 48.85% of its regional maximum. The experimental results match with the theoretical analysis and indicate that EGM2008 is suitable for gravity compensation of the high-precision and long-term INSs.

Gravity Compensation Using EGM2008 for High-Precision Long-Term Inertial Navigation Systems.

Science.gov (United States)

Wu, Ruonan; Wu, Qiuping; Han, Fengtian; Liu, Tianyi; Hu, Peida; Li, Haixia

2016-12-18

The gravity disturbance vector is one of the major error sources in high-precision and long-term inertial navigation applications. Specific to the inertial navigation systems (INSs) with high-order horizontal damping networks, analyses of the error propagation show that the gravity-induced errors exist almost exclusively in the horizontal channels and are mostly caused by deflections of the vertical (DOV). Low-frequency components of the DOV propagate into the latitude and longitude errors at a ratio of 1:1 and time-varying fluctuations in the DOV excite Schuler oscillation. This paper presents two gravity compensation methods using the Earth Gravitational Model 2008 (EGM2008), namely, interpolation from the off-line database and computing gravity vectors directly using the spherical harmonic model. Particular attention is given to the error contribution of the gravity update interval and computing time delay. It is recommended for the marine navigation that a gravity vector should be calculated within 1 s and updated every 100 s at most. To meet this demand, the time duration of calculating the current gravity vector using EGM2008 has been reduced to less than 1 s by optimizing the calculation procedure. A few off-line experiments were conducted using the data of a shipborne INS collected during an actual sea test. With the aid of EGM2008, most of the low-frequency components of the position errors caused by the gravity disturbance vector have been removed and the Schuler oscillation has been attenuated effectively. In the rugged terrain, the horizontal position error could be reduced at best 48.85% of its regional maximum. The experimental results match with the theoretical analysis and indicate that EGM2008 is suitable for gravity compensation of the high-precision and long-term INSs.

Fracture analysis of concrete gravity dam under earthquake induced ...

African Journals Online (AJOL)

In this paper, seismic fracture behavior of the concrete gravity dam using finite element (2D) theory has been studied. Bazant model which is non-linear fracture mechanics criteria as a measure of growth and smeared crack was chosen to develop profiles of the crack. Behavior of stress - strain curves of concrete as a ...

Scales of gravity

International Nuclear Information System (INIS)

Dvali, Gia; Kolanovic, Marko; Nitti, Francesco; Gabadadze, Gregory

2002-01-01

We propose a framework in which the quantum gravity scale can be as low as 10 -3 eV. The key assumption is that the standard model ultraviolet cutoff is much higher than the quantum gravity scale. This ensures that we observe conventional weak gravity. We construct an explicit brane-world model in which the brane-localized standard model is coupled to strong 5D gravity of infinite-volume flat extra space. Because of the high ultraviolet scale, the standard model fields generate a large graviton kinetic term on the brane. This kinetic term 'shields' the standard model from the strong bulk gravity. As a result, an observer on the brane sees weak 4D gravity up to astronomically large distances beyond which gravity becomes five dimensional. Modeling quantum gravity above its scale by the closed string spectrum we show that the shielding phenomenon protects the standard model from an apparent phenomenological catastrophe due to the exponentially large number of light string states. The collider experiments, astrophysics, cosmology and gravity measurements independently point to the same lower bound on the quantum gravity scale, 10 -3 eV. For this value the model has experimental signatures both for colliders and for submillimeter gravity measurements. Black holes reveal certain interesting properties in this framework

Transcriptomes and expression profiling of deep-sea corals from the Red Sea provide insight into the biology of azooxanthellate corals.

Science.gov (United States)

Yum, Lauren K; Baumgarten, Sebastian; Röthig, Till; Roder, Cornelia; Roik, Anna; Michell, Craig; Voolstra, Christian R

2017-07-25

Despite the importance of deep-sea corals, our current understanding of their ecology and evolution is limited due to difficulties in sampling and studying deep-sea environments. Moreover, a recent re-evaluation of habitat limitations has been suggested after characterization of deep-sea corals in the Red Sea, where they live at temperatures of above 20 °C at low oxygen concentrations. To gain further insight into the biology of deep-sea corals, we produced reference transcriptomes and studied gene expression of three deep-sea coral species from the Red Sea, i.e. Dendrophyllia sp., Eguchipsammia fistula, and Rhizotrochus typus. Our analyses suggest that deep-sea coral employ mitochondrial hypometabolism and anaerobic glycolysis to manage low oxygen conditions present in the Red Sea. Notably, we found expression of genes related to surface cilia motion that presumably enhance small particle transport rates in the oligotrophic deep-sea environment. This is the first study to characterize transcriptomes and in situ gene expression for deep-sea corals. Our work offers several mechanisms by which deep-sea corals might cope with the distinct environmental conditions present in the Red Sea As such, our data provide direction for future research and further insight to organismal response of deep-sea coral to environmental change and ocean warming.

Transcriptomes and expression profiling of deep-sea corals from the Red Sea provide insight into the biology of azooxanthellate corals

KAUST Repository

Yum, Lauren

2017-07-19

Despite the importance of deep-sea corals, our current understanding of their ecology and evolution is limited due to difficulties in sampling and studying deep-sea environments. Moreover, a recent re-evaluation of habitat limitations has been suggested after characterization of deep-sea corals in the Red Sea, where they live at temperatures of above 20 °C at low oxygen concentrations. To gain further insight into the biology of deep-sea corals, we produced reference transcriptomes and studied gene expression of three deep-sea coral species from the Red Sea, i.e. Dendrophyllia sp., Eguchipsammia fistula, and Rhizotrochus typus. Our analyses suggest that deep-sea coral employ mitochondrial hypometabolism and anaerobic glycolysis to manage low oxygen conditions present in the Red Sea. Notably, we found expression of genes related to surface cilia motion that presumably enhance small particle transport rates in the oligotrophic deep-sea environment. This is the first study to characterize transcriptomes and in situ gene expression for deep-sea corals. Our work offers several mechanisms by which deep-sea corals might cope with the distinct environmental conditions present in the Red Sea As such, our data provide direction for future research and further insight to organismal response of deep-sea coral to environmental change and ocean warming.

Transcriptomes and expression profiling of deep-sea corals from the Red Sea provide insight into the biology of azooxanthellate corals

KAUST Repository

Yum, Lauren; Baumgarten, Sebastian; Rö thig, Till; Roder, Cornelia; Roik, Anna Krystyna; Michell, Craig; Voolstra, Christian R.

2017-01-01

Despite the importance of deep-sea corals, our current understanding of their ecology and evolution is limited due to difficulties in sampling and studying deep-sea environments. Moreover, a recent re-evaluation of habitat limitations has been suggested after characterization of deep-sea corals in the Red Sea, where they live at temperatures of above 20 °C at low oxygen concentrations. To gain further insight into the biology of deep-sea corals, we produced reference transcriptomes and studied gene expression of three deep-sea coral species from the Red Sea, i.e. Dendrophyllia sp., Eguchipsammia fistula, and Rhizotrochus typus. Our analyses suggest that deep-sea coral employ mitochondrial hypometabolism and anaerobic glycolysis to manage low oxygen conditions present in the Red Sea. Notably, we found expression of genes related to surface cilia motion that presumably enhance small particle transport rates in the oligotrophic deep-sea environment. This is the first study to characterize transcriptomes and in situ gene expression for deep-sea corals. Our work offers several mechanisms by which deep-sea corals might cope with the distinct environmental conditions present in the Red Sea As such, our data provide direction for future research and further insight to organismal response of deep-sea coral to environmental change and ocean warming.

Hydrographic Data from the U.S. Naval Oceanographic Office: Persian Gulf, Southern Red Sea, and Arabian Sea 1923-1996

National Research Council Canada - National Science Library

Alessi, Carrol

1999-01-01

Temperature-salinity-depth profile data were obtained for the Persian Gulf, Southern Red Sea and parts of the Arabian Sea from the Master Oceanographic Observations Data Set (MOODS), located at the U.S...

Geology and assessment of undiscovered oil and gas resources of the Hope Basin Province, 2008

Science.gov (United States)

Bird, Kenneth J.; Houseknecht, David W.; Pitman, Janet K.; Moore, Thomas E.; Gautier, Donald L.

2018-01-04

The Hope Basin, an independent petroleum province that lies mostly offshore in the southern Chukchi Sea north of the Chukotka and Seward Peninsulas and south of Wrangel Island, the Herald Arch, and the Lisburne Peninsula, is the largest in a series of postorogenic (successor) basins in the East Siberian-Chukchi Sea region and the only one with exploratory-well control and extensive seismic coverage.In spite of the seismic coverage and well data, the petroleum potential of the Hope Basin Province is poorly known. The adequacy of hydrocarbon charge, in combination with uncertainties in source-rock potential and maturation, was the greatest risk in this assessment. A single assessment unit was defined and assessed, resulting in mean estimates of undiscovered, technically recoverable resources that include ~3 million barrels of oil and 650 billion cubic feet of nonassociated gas.

Element bow profiles from new and irradiated CANDU fuel bundles

International Nuclear Information System (INIS)

Dennier, D.; Manzer, A.M.; Ryz, M.A.

1996-01-01

Improved methods of measuring element profiles on new CANDU fuel bundles were developed at the Sheridan Park Engineering Laboratory, and have now been applied in the hot cells at Whiteshell Laboratories. For the first time, the outer element profiles have been compared between new, out-reactor tested, and irradiated fuel elements. The comparison shows that irradiated element deformation is similar to that observed on elements in out-reactor tested bundles. In addition to the restraints applied to the element via appendages, the element profile appears to be strongly influenced by gravity and the end loads applied by local deformation of the endplate. Irradiation creep in the direction of gravity also tends to be a dominant factor. (author)

PPN-limit of Fourth Order Gravity inspired by Scalar-Tensor Gravity

OpenAIRE

Capozziello, S.; Troisi, A.

2005-01-01

Based on the {\\it dynamical} equivalence between higher order gravity and scalar-tensor gravity the PPN-limit of fourth order gravity is discussed. We exploit this analogy developing a fourth order gravity version of the Eddington PPN-parameters. As a result, Solar System experiments can be reconciled with higher order gravity, if physical constraints descending from experiments are fulfilled.

Effects of Sea-Surface Waves and Ocean Spray on Air-Sea Momentum Fluxes

Science.gov (United States)

Zhang, Ting; Song, Jinbao

2018-04-01

The effects of sea-surface waves and ocean spray on the marine atmospheric boundary layer (MABL) at different wind speeds and wave ages were investigated. An MABL model was developed that introduces a wave-induced component and spray force to the total surface stress. The theoretical model solution was determined assuming the eddy viscosity coefficient varied linearly with height above the sea surface. The wave-induced component was evaluated using a directional wave spectrum and growth rate. Spray force was described using interactions between ocean-spray droplets and wind-velocity shear. Wind profiles and sea-surface drag coefficients were calculated for low to high wind speeds for wind-generated sea at different wave ages to examine surface-wave and ocean-spray effects on MABL momentum distribution. The theoretical solutions were compared with model solutions neglecting wave-induced stress and/or spray stress. Surface waves strongly affected near-surface wind profiles and sea-surface drag coefficients at low to moderate wind speeds. Drag coefficients and near-surface wind speeds were lower for young than for old waves. At high wind speeds, ocean-spray droplets produced by wind-tearing breaking-wave crests affected the MABL strongly in comparison with surface waves, implying that wave age affects the MABL only negligibly. Low drag coefficients at high wind caused by ocean-spray production increased turbulent stress in the sea-spray generation layer, accelerating near-sea-surface wind. Comparing the analytical drag coefficient values with laboratory measurements and field observations indicated that surface waves and ocean spray significantly affect the MABL at different wind speeds and wave ages.

Terrestrial gravity data analysis for interim gravity model improvement

Science.gov (United States)

1987-01-01

This is the first status report for the Interim Gravity Model research effort that was started on June 30, 1986. The basic theme of this study is to develop appropriate models and adjustment procedures for estimating potential coefficients from terrestrial gravity data. The plan is to use the latest gravity data sets to produce coefficient estimates as well as to provide normal equations to NASA for use in the TOPEX/POSEIDON gravity field modeling program.

Effect of surface tension on the dynamical behavior of bubble in rotating fluids under low gravity environment

Science.gov (United States)

Hung, R. J.; Tsao, Y. D.; Leslie, Fred W.; Hong, B. B.

1988-01-01

Time dependent evolutions of the profile of free surface (bubble shapes) for a cylindrical container partially filled with a Newtonian fluid of constant density, rotating about its axis of symmetry, have been studied. Numerical computations of the dynamics of bubble shapes have been carried out with the following situations: (1) linear functions of spin-up and spin-down in low and microgravity environments, (2) linear functions of increasing and decreasing gravity enviroment in high and low rotating cylidner speeds, (3) step functions of spin-up and spin-down in a low gravity environment, and (4) sinusoidal function oscillation of gravity environment in high and low rotating cylinder speeds. The initial condition of bubble profiles was adopted from the steady-state formulations in which the computer algorithms have been developed by Hung and Leslie (1988), and Hung et al. (1988).

Chlorophyll-a profiles collected by various vessels in the Atlantic Ocean and adjoining seas from 03/02/1961 to 10/21/1992 (NODC Accession 9300147)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Chlorophyll-a profiles were collected in the Atlantic Ocean and adjoining seas from March 2, 1961 to October 21, 1992. The data were collected by multiple...

Ross Sea oceanographic data, 1983-1987 : USCGC Glacier, January-February 1983; USCGC Polar Sea, January-February 1984; USCGC Polar Star, February 1985; USCGC Polar Sea, February 1987 (NODC Accession 8900108)

Data.gov (United States)