Science.gov

Sample records for alaska shallow-water species

  1. 75 FR 54290 - Fisheries of the Economic Exclusive Zone Off Alaska; Shallow-Water Species Fishery by Vessels...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-07

    ... Exclusive Zone Off Alaska; Shallow- Water Species Fishery by Vessels Using Trawl Gear in the Gulf of Alaska... comprise the shallow-water species fishery by vessels using trawl gear in the Gulf of Alaska (GOA). This..., NMFS is prohibiting directed fishing for the shallow-water species fishery by vessels using trawl...

  2. 77 FR 19146 - Fisheries of the Economic Exclusive Zone Off Alaska; Shallow-Water Species Fishery by Vessels...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-30

    ... Exclusive Zone Off Alaska; Shallow- Water Species Fishery by Vessels Using Trawl Gear in the Gulf of Alaska... comprise the shallow-water species fishery by vessels using trawl gear in the Gulf of Alaska (GOA). This..., NMFS is prohibiting directed fishing for the shallow-water species fishery by vessels using trawl...

  3. 77 FR 33103 - Fisheries of the Economic Exclusive Zone Off Alaska; Shallow-Water Species Fishery by Vessels...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-05

    ... Exclusive Zone Off Alaska; Shallow- Water Species Fishery by Vessels Using Trawl Gear in the Gulf of Alaska... comprise the shallow-water species fishery by vessels using trawl gear in the Gulf of Alaska (GOA). This..., NMFS is prohibiting directed fishing for the shallow-water species fishery by vessels using trawl...

  4. 76 FR 55276 - Fisheries of the Economic Exclusive Zone Off Alaska; Shallow-Water Species Fishery by Vessels...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-07

    ... Exclusive Zone Off Alaska; Shallow- Water Species Fishery by Vessels Using Trawl Gear in the Gulf of Alaska... comprise the shallow-water species fishery by vessels using trawl gear in the Gulf of Alaska (GOA). This..., NMFS is prohibiting directed fishing for the shallow-water species fishery by vessels using trawl...

  5. 77 FR 42193 - Fisheries of the Economic Exclusive Zone Off Alaska; Shallow-Water Species Fishery by Vessels...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-18

    ... Economic Exclusive Zone Off Alaska; Shallow- Water Species Fishery by Vessels Using Trawl Gear in the Gulf... for species that comprise the shallow-water species fishery by vessels using trawl gear in the Gulf of... gear in the GOA. The species and species groups that comprise the shallow-water species fishery...

  6. 75 FR 56017 - Fisheries of the Exclusive Economic Zone Off Alaska; Shallow-Water Species by Vessels Using Trawl...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-15

    ... Economic Zone Off Alaska; Shallow- Water Species by Vessels Using Trawl Gear in the Gulf of Alaska AGENCY...-water species by vessels using trawl gear in the Gulf of Alaska (GOA). This action is necessary to fully... 679. NMFS prohibited directed fishing for shallow-water species by vessels using trawl gear in the...

  7. 76 FR 39794 - Fisheries of the Economic Exclusive Zone Off Alaska; Shallow-Water Species Fishery by Catcher...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-07

    ... Exclusive Zone Off Alaska; Shallow- Water Species Fishery by Catcher/Processors in the Gulf of Alaska AGENCY... the shallow-water species fishery for catcher/processors subject to sideboard limits established under... 2011 Pacific halibut prohibited species catch (PSC) sideboard limit specified for the...

  8. 76 FR 57679 - Fisheries of the Exclusive Economic Zone Off Alaska; Shallow-Water Species by Vessels Using Trawl...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-16

    ... Economic Zone Off Alaska; Shallow- Water Species by Vessels Using Trawl Gear in the Gulf of Alaska AGENCY...-water species by vessels using trawl gear in the Gulf of Alaska (GOA) for 48 hours. This action is...-water species by vessels using trawl gear in the GOA under Sec. 679.21(d)(7)(i) on September 3, 2011...

  9. Shallow-water habitat use by Bering Sea flatfishes along the central Alaska Peninsula

    NASA Astrophysics Data System (ADS)

    Hurst, Thomas P.

    2016-05-01

    Flatfishes support a number of important fisheries in Alaskan waters and represent major pathways of energy flow through the ecosystem. Despite their economic and ecological importance, little is known about the use of habitat by juvenile flatfishes in the eastern Bering Sea. This study describes the habitat characteristics of juvenile flatfishes in coastal waters along the Alaska Peninsula and within the Port Moller-Herendeen Bay system, the largest marine embayment in the southern Bering Sea. The two most abundant species, northern rock sole and yellowfin sole, differed slightly in habitat use with the latter occupying slightly muddier substrates. Both were more common along the open coastline than they were within the bay, whereas juvenile Alaska plaice were more abundant within the bay than along the coast and used shallow waters with muddy, high organic content sediments. Juvenile Pacific halibut showed the greatest shift in distribution between age classes: age-0 fish were found in deeper waters (~ 30 m) along the coast, whereas older juveniles were found in the warmer, shallow waters within the bay, possibly due to increased thermal opportunities for growth in this temperature-sensitive species. Three other species, starry flounder, flathead sole, and arrowtooth flounder, were also present, but at much lower densities. In addition, the habitat use patterns of spring-spawning flatfishes (northern rock sole, Pacific halibut, and Alaska plaice) in this region appear to be strongly influenced by oceanographic processes that influence delivery of larvae to coastal habitats. Overall, use of the coastal embayment habitats appears to be less important to juvenile flatfishes in the Bering Sea than in the Gulf of Alaska.

  10. New species and new records of bryozoans from shallow waters of Madeira Island.

    PubMed

    Souto, Javier; Kaufmann, Manfred J; Canning-Clode, João

    2015-03-03

    Two new species of bryozoans encrusting subtidal rocks are described from the shallow waters of Madeira Island. We describe one cyclostome, Favosipora purpurea sp. nov., which represents the first record of this genus in the Atlantic Ocean, and one cheilostome, Rhynchozoon papuliferum sp. nov. In addition, one species, Beania maxilladentata, is recorded for the first time outside of Rio de Janeiro, Brazil. Six other species previously recorded in Madeira are redescribed to provide new data and SEM images.

  11. Cheilopallene ogasawarensis, a New Species of Shallow-Water Pycnogonid (Arthropoda: Pycnogonida) from the Ogasawara (Bonin) Islands, Japan, Northwest Pacific.

    PubMed

    Nakamura, Koichiro; Akiyama, Tadashi

    2015-08-05

    A new species of pycnogonid recorded from the shallow waters of Ogasawara (Bonin) Island, Japan, Cheilopallene ogasawarensis n. sp. is described, illustrated and compared with similar species. Cheilopallene ogasawarensis is only the third pycnogonid species recorded from these islands. Morphological characters clearly distinguish the new species from its geographically closest congener C. nodulosa Hong and Kim, 1987, also recorded from Japanese waters.

  12. Studies of ambient noise in shallow water environments off Mexico and Alaska: characteristics, metrics and time-synchronization applications

    NASA Astrophysics Data System (ADS)

    Guerra, Melania

    Sound in the ocean originates from multiple mechanisms, both natural and anthropogenic. Collectively, underwater ambient noise accumulates valuable information about both its sources and the oceanic environment that propagates this noise. Characterizing the features of ambient noise source mechanisms is challenging, but essential, for properly describing an acoustic environment. Disturbances to a local acoustic environment may affect many aquatic species that have adapted to be heavily dependent on this particular sense for survival functions. In the case of marine mammals, which are federally protected, demand exists for understanding such potential impacts, which drives important scientific efforts that utilize passive acoustic monitoring (PAM) tools to inform regulatory decisions. This dissertation presents two independent studies that use PAM data to investigate the characteristics of source mechanisms that dominate ambient noise in two diverse shallow water environments. The study in Chapter 2 directly addresses the concern of how anthropogenic activities can degrade the effectiveness of PAM. In the Alaskan Beaufort Sea, an environment where ambient noise is normally dominated by natural causes, seismic surveys create impulsive sounds to map the composition of the bottom. By inspecting single-sensor PAM data, the spectral characteristics of seismic survey airgun reverberation are measured, and their contribution to the overall ambient noise is quantified. This work is relevant to multiple ongoing mitigation protocols that rely on PAM to acoustically detect marine mammal presence during industrial operations. Meanwhile, Chapter 3 demonstrates that by analyzing data from multiple PAM sensors, features embedded in both directional and omnidirectional ambient noise can be used to develop new time-synchronization processing techniques for aligning autonomous elements of an acoustic array, a tool commonly used in PAM for detecting and tracking marine mammals. Using

  13. Taxonomic review of tropical western Atlantic shallow water Drilliidae (Mollusca: Gastropoda: Conoidea) including descriptions of 100 new species.

    PubMed

    Fallon, Phillip J Jr

    2016-03-14

    A review of the literature and examination of over 3,200 specimens of shallow water (<200 m) tropical western Atlantic (TWA) Drilliidae Olson, 1964 in museum and private collections has resulted in the recognition of numerous previously undescribed species, 100 of which are proposed here for the first time. A total of 65 names were found in the literature. Of these, 48 are considered valid, 16 synonyms, and one nomen dubium. In addition, characteristics that distinguish each genus currently in use for TWA shallow water species have indicated the need for reassignment (new combinations within Drilliidae) of 15 species. Some nomenclatural actions have come about from the literature review and include one taxon placed in junior synonymy (under an older name recently re-discovered) and one new name for a junior homonym. Two neotypes, five lectotype designations, and one new name are also proposed. Altogether, nomenclatural actions on 17% of valid previously described taxa are proposed. The 100 proposed names are placed in 12 available and one new genus: Agladrillia Woodring, 1928 (2), Bellaspira Conrad, 1868 (7), Calliclava McLean, 1971 (3), Cerodrillia Bartsch & Rehder, 1939 (11), Clathrodrillia Dall, 1918 (6), Decoradrillia, new genus (4), Douglassia Bartsch, 1934 (4), Fenimorea Bartsch, 1934 (15), Leptadrillia Woodring, 1928 (12), Lissodrillia Bartsch & Rehder, 1939 (8), Neodrillia Bartsch, 1943 (2), Splendrillia Hedley, 1922 (13), and Syntomodrillia Woodring, 1928 (13). These are the first reports of Calliclava in the western Atlantic, previously known only from the eastern Pacific. The new genus, Decoradrillia, is proposed to hold four new species and one existing that share a unique shell microsculpture and other morphological traits. One genus, Drillia Gray, 1838, is not currently believed to have TWA representatives. Three genera comprised exclusively of bathyal species are not treated in this work: Clavus Monfort, 1810 (=Eldridgea Bartsch, 1934), Globidrillia

  14. Shallow-Water Propagation

    DTIC Science & Technology

    2016-06-07

    Shallow- Water Propagation William L. Siegmann Rensselaer Polytechnic Institute 110 Eighth Street Troy, New York 12180-3590 phone: (518) 276...ocean_acoustics LONG-TERM GOALS Develop methods for propagation and coherence calculations in complex shallow- water environments, determine...intensity and coherence. APPROACH (A) Develop high accuracy PE techniques for applications to shallow- water sediments, accounting for

  15. Color pattern variation in a shallow-water species of opisthobranch mollusc.

    PubMed

    Valdés, Ángel; Ornelas-Gatdula, Elysse; Dupont, Anne

    2013-02-01

    The color pattern of benthic opisthobranch sea slugs (Mollusca: Gastropoda) appears to play an important defensive role, and numerous species seem to have aposematic (warning) colorations. Color pattern is an important trait for opisthobranch identification-this conclusion is based on the assumption that most species have limited color variation. For those species in which color variation is recognized, the reasons for the variation remain unknown. In this paper we study Philinopsis pusa, a benthic putative species of opisthobranch sea slug with a broad range of color pattern. Lighter individuals appear to be camouflaged on the white sand environment in which the animals are typically found, whereas darker individuals appear conspicuously different from their background. Because of its broad color variation, P. pusa has been subdivided into different species. Animals were collected and observed in the Bahamas during a 6-year span. The color pattern of the specimens was subjectively classified into five phenotypic classes. Two mitochondrial genes (16S, CO1) were sequenced from 41 specimens. The association between color pattern, body length, burrowing escaping behavior, and the genetic structure of the population was investigated. We found two genetically distinct groups in the target population but no significant association between color pattern and genetic structure. Additionally, there was no significant association between color pattern and ontogeny or defensive behavior in these organisms. The present paper suggests that general assumptions on the biological and evolutionary role of color in opisthobranchs need to be carefully evaluated.

  16. Shallow Water Acoustics Studies

    DTIC Science & Technology

    2015-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Shallow Water Acoustics Studies James F. Lynch MS #12...N00014-14-1-0040 http://acoustics.whoi.edu/sw06/ LONG TERM GOALS The long term goals of our shallow water acoustics work are to: 1) understand the...nature of low frequency (10-1500 Hz) acoustic propagation, scattering and noise in shallow water when strong oceanic variability is present in the

  17. Species boundaries and phylogenetic relationships between Atlanto-Mediterranean shallow-water and deep-sea coral associated Hexadella species (Porifera, Ianthellidae).

    PubMed

    Reveillaud, Julie; Remerie, Thomas; van Soest, Rob; Erpenbeck, Dirk; Cárdenas, Paco; Derycke, Sofie; Xavier, Joana R; Rigaux, Annelien; Vanreusel, Ann

    2010-07-01

    Coral reefs constitute the most diverse ecosystem of the marine realm and an increasing number of studies are focusing on coral species boundaries, distribution, and on processes that control species ranges. However, less attention has been paid to coral associated species. Deep-sea sponges dominate cold-water coral ecosystems, but virtually nothing is known about their molecular diversity. Moreover, species boundaries based on morphology may sometimes be inadequate, since sponges have few diagnostic characters. In this study, we investigated the molecular diversity within the genus Hexadella (Porifera, Demospongiae, Verongida, Ianthellidae) from the European shallow-water environment to the deep-sea coral ecosystems. Three molecular markers were used: one mitochondrial (COI) and two nuclear gene fragments (28S rDNA and the ATPS intron). Phylogenetic analyses revealed deeply divergent deep-sea clades congruent across the mitochondrial and nuclear markers. One clade contained specimens from the Irish, the Scottish, and the Norwegian margins and the Greenland Sea (Hexadella dedritifera) while another clade contained specimens from the Ionian Sea, the Bay of Biscay, and the Irish margin (H. cf. dedritifera). Moreover, these deeply divergent deep-sea clades showed a wide distribution suggesting a connection between the reefs. The results also point to the existence of a new deep-sea species (Hexadella sp.) in the Mediterranean Sea and of a cryptic shallow-water species (Hexadella cf. pruvoti) in the Gorringe Bank. In contrast, low genetic differentiation between H. cf. dedritifera and H. pruvoti from the Mediterranean Sea was observed. All Hexadella racovitzai specimens from the Mediterranean Sea (shallow and deep) to the Atlantic formed a monophyletic group.

  18. A Five-Year, In Situ Growth Study on Shallow-Water Populations of the Gorgonian Octocoral Calcigorgia spiculifera in the Gulf of Alaska

    PubMed Central

    Stone, Robert P.; Malecha, Patrick W.; Masuda, Michele M.

    2017-01-01

    Gorgonian octocorals are the most abundant corals in Alaska where they provide important structural habitat for managed species of demersal fish and invertebrates. Fifty-nine gorgonian species have been reported from Alaska waters but little is known about their life history characteristics to help us gauge their ability to recover from seafloor disturbance. Colonies of the holaxonian Calcigorgia spiculifera were tagged beginning in 1999 at three sites in Chatham Strait, Southeast Alaska, using scuba and their growth measured annually for up to 5 years. Colonies were video recorded, and computer image analysis tools provided calibration of video images for measuring the length of several branches. Growth data indicate that C. spiculifera grows much slower (6.0 mm yr-1) than other gorgonians in Alaska for which there are data and that intraspecific growth is highly variable. We fit a Bayesian linear mixed-effects model that showed that average colony growth was significantly reduced with warmer temperature and presence of necrosis. The model further indicated that growth may slow among larger (older) colonies. Based on these results and previous studies, we propose that gorgonian growth rates are taxonomically constrained at the Suborder level and that holaxonians grow the slowest followed by scleraxonians and calcaxonians (2–3 times as fast). Findings of this study indicate that it would take approximately 60 years for C. spiculifera to grow to its maximum size and depending on the location and size of the parental standing stock, at least one and possibly 10 additional years for recruitment to occur. Our results further indicate that colonies that are injured, perhaps chronically in areas of frequent disturbance, grow at slower rates and if the current trend of ocean warming continues then we can expect these corals to grow more slowly, and the habitats they form will require more time to recover from disturbance. PMID:28068374

  19. Kliopsyllus andeep sp. n. (Copepoda: Harpacticoida) from the Antarctic deep sea—a copepod closely related to certain shallow-water species

    NASA Astrophysics Data System (ADS)

    Veit-Köhler, Gritta

    2004-07-01

    The international scientific deep-sea cruise ANDEEP-2 (ANT XIX/4) to the Scotia Arc and the northern Weddell Sea in 2002 revealed a new species of the family Paramesochridae (Copepoda: Harpacticoida). Kliopsyllus andeep sp. n. can be distinguished from its congeners by characteristics such as a two-segmented endopod on the fourth leg and an additional seta on the endopod of the third leg. The most striking feature is its strong, flexed, chitinous thorns on the telson. Only three species in the family have such appendages, all of them interstitial, shallow-water species. Because the new species lacks the strong abdominal muscle observed by Kunz in Kliopsyllus furcavaricatus Kunz, 1974, it cannot spread its furcal rami using the thorns on the telson as antagonists the way the shallow-water species does. The furcal-rami spreading system, which is an adaptation to interstitial living, for K. andeep sp. n. is irrelevant, because the species has been collected from muddy sediments. Therefore, the abdominal muscle might have been lost during the species' evolution.

  20. Molecular dynamics simulations of the Nip7 proteins from the marine deep- and shallow-water Pyrococcus species

    PubMed Central

    2014-01-01

    Background The identification of the mechanisms of adaptation of protein structures to extreme environmental conditions is a challenging task of structural biology. We performed molecular dynamics (MD) simulations of the Nip7 protein involved in RNA processing from the shallow-water (P. furiosus) and the deep-water (P. abyssi) marine hyperthermophylic archaea at different temperatures (300 and 373 K) and pressures (0.1, 50 and 100 MPa). The aim was to disclose similarities and differences between the deep- and shallow-sea protein models at different temperatures and pressures. Results The current results demonstrate that the 3D models of the two proteins at all the examined values of pressures and temperatures are compact, stable and similar to the known crystal structure of the P. abyssi Nip7. The structural deviations and fluctuations in the polypeptide chain during the MD simulations were the most pronounced in the loop regions, their magnitude being larger for the C-terminal domain in both proteins. A number of highly mobile segments the protein globule presumably involved in protein-protein interactions were identified. Regions of the polypeptide chain with significant difference in conformational dynamics between the deep- and shallow-water proteins were identified. Conclusions The results of our analysis demonstrated that in the examined ranges of temperatures and pressures, increase in temperature has a stronger effect on change in the dynamic properties of the protein globule than the increase in pressure. The conformational changes of both the deep- and shallow-sea protein models under increasing temperature and pressure are non-uniform. Our current results indicate that amino acid substitutions between shallow- and deep-water proteins only slightly affect overall stability of two proteins. Rather, they may affect the interactions of the Nip7 protein with its protein or RNA partners. PMID:25315147

  1. Application of DNA barcoding in biodiversity studies of shallow-water octocorals: molecular proxies agree with morphological estimates of species richness in Palau

    NASA Astrophysics Data System (ADS)

    McFadden, C. S.; Brown, A. S.; Brayton, C.; Hunt, C. B.; van Ofwegen, L. P.

    2014-06-01

    The application of DNA barcoding to anthozoan cnidarians has been hindered by their slow rates of mitochondrial gene evolution and the failure to identify alternative molecular markers that distinguish species reliably. Among octocorals, however, multilocus barcodes can distinguish up to 70 % of morphospecies, thereby facilitating the identification of species that are ecologically important but still very poorly known taxonomically. We tested the ability of these imperfect DNA barcodes to estimate species richness in a biodiversity survey of the shallow-water octocoral fauna of Palau using multilocus ( COI, mtMutS, 28S rDNA) sequences obtained from 305 specimens representing 38 genera of octocorals. Numbers and identities of species were estimated independently (1) by a taxonomic expert using morphological criteria and (2) by assigning sequences to molecular operational taxonomic units (MOTUs) using predefined genetic distance thresholds. Estimated numbers of MOTUs ranged from 73 to 128 depending on the barcode and distance threshold applied, bracketing the estimated number of 118 morphospecies. Concordance between morphospecies identifications and MOTUs ranged from 71 to 75 % and differed little among barcodes. For the speciose and ecologically dominant genus Sinularia, however, we were able to identify 95 % of specimens correctly simply by comparing mtMutS sequences and in situ photographs of colonies to an existing vouchered database. Because we lack a clear understanding of species boundaries in most of these taxa, numbers of morphospecies and MOTUs are both estimates of the true species diversity, and we cannot currently determine which is more accurate. Our results suggest, however, that the two methods provide comparable estimates of species richness for shallow-water Indo-Pacific octocorals. Use of molecular barcodes in biodiversity surveys will facilitate comparisons of species richness and composition among localities and over time, data that do not

  2. Shallow-Water Mud Acoustics

    DTIC Science & Technology

    2015-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Shallow- Water Mud Acoustics William L. Siegmann...shallow water over mud sediments and of acoustic detection, localization, and classification of objects buried in mud. OBJECTIVES • Develop...including long-range conveyance of information; detection, localization, and classification of objects buried in mud; and improvement of shallow water

  3. Revision of Neolebouria Gibson, 1976 (Digenea: Opecoelidae), with Trilobovarium n. g., for species infecting tropical and subtropical shallow-water fishes.

    PubMed

    Martin, Storm B; Cutmore, Scott C; Cribb, Thomas H

    2017-03-01

    A new opecoelid trematode is reported from fishes of the Lethrinidae, Lutjanidae and Nemipteridae off Lizard Island on the northern Great Barrier Reef, Australia. The new species keys to Neolebouria Gibson, 1976 and shows strong similarity to several species of that genus, but is not consistent with the type-species, N. georgiensis Gibson, 1976, or others known from temperate/polar and/or deep-sea fishes. The new species is also phylogenetically distant from N. lanceolata (Price, 1934) Reimer, 1987, the only representative of the genus for which molecular data are available. A new genus, Trilobovarium n. g., is proposed for the new species, T. parvvatis n. sp. Eight morphologically similar species, previously recognised as belonging to Neolebouria, from shallow-water, mostly tropical/subtropical fishes, are transferred to Trilobovarium: T. diacopae (Nagaty & Abdel Aal, 1962) n. comb.; T. ira (Yamaguti, 1940) n. comb.; T. khalili (Ramadan, 1983) n. comb.; T. krusadaiense (Gupta, 1956) n. comb.; T. lineatum (Aken'Ova & Cribb, 2001) n. comb.; T. moretonense (Aken'Ova & Cribb, 2001) n. comb.; T. palauense (Machida, 2014) n. comb.; and T. truncatum (Linton, 1940) n. comb. Paramanteriella Li, Qiu & Zhang, 1988 is resurrected for five species of Neolebouria with a post-bifurcal genital pore: P. cantherini Li, Qiu & Zhang, 1988; P. capoori (Jaiswal, Upadhyay, Malhotra, Dronen & Malhotra, 2014) n. comb.; P. confusa (Overstreet, 1969) n. comb.; P. leiperi (Gupta, 1956) n. comb.; and P. pallenisca (Shipley & Hornell, 1905) n. comb. Neolebouria georgenascimentoi Bray, 2002, a species with an exceptionally long cirrus-sac, is transferred to Bentholebouria Andres, Pulis & Overstreet, 2004 as B. georgenascimentoi (Bray, 2002) n. comb., and N. maorum (Allison, 1966) Gibson 1976, an unusual species known from cephalopods, is designated a species incertae sedis. Eleven species are retained in a revised concept of Neolebouria.

  4. Adaptation and evolution of deep-sea scale worms (Annelida: Polynoidae): insights from transcriptome comparison with a shallow-water species

    PubMed Central

    Zhang, Yanjie; Sun, Jin; Chen, Chong; Watanabe, Hiromi K.; Feng, Dong; Zhang, Yu; Chiu, Jill M.Y.; Qian, Pei-Yuan; Qiu, Jian-Wen

    2017-01-01

    Polynoid scale worms (Polynoidae, Annelida) invaded deep-sea chemosynthesis-based ecosystems approximately 60 million years ago, but little is known about their genetic adaptation to the extreme deep-sea environment. In this study, we reported the first two transcriptomes of deep-sea polynoids (Branchipolynoe pettiboneae, Lepidonotopodium sp.) and compared them with the transcriptome of a shallow-water polynoid (Harmothoe imbricata). We determined codon and amino acid usage, positive selected genes, highly expressed genes and putative duplicated genes. Transcriptome assembly produced 98,806 to 225,709 contigs in the three species. There were more positively charged amino acids (i.e., histidine and arginine) and less negatively charged amino acids (i.e., aspartic acid and glutamic acid) in the deep-sea species. There were 120 genes showing clear evidence of positive selection. Among the 10% most highly expressed genes, there were more hemoglobin genes with high expression levels in both deep-sea species. The duplicated genes related to DNA recombination and metabolism, and gene expression were only enriched in deep-sea species. Deep-sea scale worms adopted two strategies of adaptation to hypoxia in the chemosynthesis-based habitats (i.e., rapid evolution of tetra-domain hemoglobin in Branchipolynoe or high expression of single-domain hemoglobin in Lepidonotopodium sp.).

  5. A new species of Monocheres Stock (Copepoda, Siphonostomatoida, Asterocheridae) from shallow waters off Florida, USA: an unexpected discovery

    PubMed Central

    Suárez-Morales, Eduardo

    2016-01-01

    Abstract The rare asterocherid copepod genus Monocheres, ectosymbionts of corals and sponges, contains only two species, one from Mauritius (Indian Ocean) and the other one from Brazil (western Atlantic). From the analysis of the digestive caecum contents of the benthic hesionid polychaete Hesione picta Müller, 1858, an adult female of an undescribed species of Monocheres was unexpectedly recovered; it is the third species of this rare asterocherid genus. The new species, Monocheres sergioi sp. n., has the distinctive reduction of the fifth leg as a process with a single seta. It differs from its two other congeners by several characters including the presence of an inner basipodal spine, the armature details of the third exopodal segment of leg 1, the shape of the cephalosome and pedigerous somites 3 and 4, and the ornamentation of the postero-lateral corners of the genital double-somite. The main synapomorphies include the presence of spinules along the posterior margin of the first leg coxal sclerite and the reduced, spiniform coxal seta on leg 4. The biology and feeding habits of the polychaete containing this specimen suggests that the copepod was ingested as an ectosymbiont from sponges or coral but it is also possible that it was consumed from an ophiurid echinoderm. This finding allows an expansion of the genus geographical distribution in the northwestern Atlantic. A key to the species of Monocheres is also provided. PMID:27551233

  6. Shallow water marine gammaridean amphipods of Pulau Tioman, Malaysia, with the description of a new species

    PubMed Central

    Azman, B.A.R.; Othman, B.H.R.

    2013-01-01

    Abstract Eleven taxa including one new species of gammaridean amphipods are reported from the waters of Pulau Tioman. The presence of Tethygeneia sunda sp. n. represents the first record of the genus from the South China Sea. Additional material of Ampelisca brevicornis (Costa, 1853); Cymadusa vadosa Imbach, 1967; Paradexamine setigera Hirayama, 1984; Ericthonius pugnax (Dana, 1853); Leucothoe furina (Savigny, 1816); Microlysias xenokeras (Stebbing, 1918); Monoculodes muwoni Jo, 1990 are identified from the South China Sea, supporting previous records by Lowry (2000), Huang (1994), Imbach (1967), Margulis (1968) and Nagata (1959). Three additional species, Gitanopsis pusilla K.H. Barnard, 1916, Liljeborgia japonica Nagata, 1965b and Latigammaropsis atlantica (Stebbing, 1888), whilst previously reported from the neighbouring waters, comprise new records for the South China Sea. PMID:24146563

  7. Accelerated shallow water modeling

    NASA Astrophysics Data System (ADS)

    Gandham, Rajesh; Medina, David; Warburton, Timothy

    2015-04-01

    ln this talk we will describe our ongoing developments in accelerated numerical methods for modeling tsunamis, and oceanic fluid flows using two dimensional shallow water model and/or three dimensional incompressible Navier Stokes model discretized with high order discontinuous Galerkin methods. High order discontinuous Galerkin methods can be computationally demanding, requiring extensive computational time to simulate real time events on traditional CPU architectures. However, recent advances in computing architectures and hardware aware algorithms make it possible to reduce simulation time and provide accurate predictions in a timely manner. Hence we tailor these algorithms to take advantage of single instruction multiple data (SIMD) architecture that is seen in modern many core compute devices such as GPUs. We will discuss our unified and extensive many-core programming library OCCA that alleviates the need to completely re-design the solvers to keep up with constantly evolving parallel programming models and hardware architectures. We will present performance results for the flow simulations demonstrating performance leveraging multiple different multi-threading APIs on GPU and CPU targets.

  8. Species composition and dietary relationships in a brackish shallow water fish assemblage in the Bothnian Sea, Sweden

    NASA Astrophysics Data System (ADS)

    Thorman, Staffan; Wiederholm, Anne-Marie

    1984-09-01

    A nearshore fish assemblage inhabiting a shallow bay in the southern Bothnian Sea, Sweden, with demanding environmental conditions (c. 5‰; >15°C during 4 months 1980 and 1 month 1981) was studied during a two-year period, in 1980 and 1981. Seasonal distribution patterns, dietary relationships, and growth rates were studied in Pungitius pungitius (L.), Pomatoschistus minutus (Pallas.), Gasterosteus aculeatus (L.), Phoxinus phoxinus (L.), Pomatoschistus microps (Krøyer) and Gobius niger L. The structure of the juvenile populations changed both over seasons and years but the adult populations remained constant. Lower water temperature, fewer individuals, lower and delayed fish growth, and lower interspecific food overlaps were found in 1981 compared to 1980. Few significant correlations were found in both years between the following community parameters: diversity, niche width, food overlap, and the proportion of each species in the fish assemblage. According to these results it is suggested that food competition and resource partitioning were of minor importance for the structuring of the fish community in the present area. Rather, the extreme salinity and the fluctuations in temperature regulated the fish populations. One may conclude that the populations of juveniles were more influenced by short-term changes in the environment than those of the adults.

  9. 77 FR 54837 - Fisheries of the Economic Exclusive Zone Off Alaska; Shallow-Water Species Fishery by Vessels...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-06

    ... AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA..., octopuses, and sculpins. This prohibition does not apply to fishing for pollock by vessels using pelagic.... Lindsay Fullenkamp, Acting Deputy Director, Office of Sustainable Fisheries, National Marine...

  10. 77 FR 12213 - Fisheries of the Economic Exclusive Zone Off Alaska; Shallow-Water Species by Amendment 80...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-29

    ... would prevent NMFS from responding to the most recent fisheries data in a timely fashion and would delay... National Oceanic and Atmospheric Administration 50 CFR Part 679 RIN 0648-XB044 Fisheries of the Economic...: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA),...

  11. 76 FR 59064 - Fisheries of the Exclusive Economic Zone Off Alaska; Shallow-Water Species by Vessels Using Trawl...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-23

    ... Confidential Business Information or otherwise sensitive or protected information. NMFS will accept anonymous comments (enter N/A in the required fields, if you wish to remain anonymous). Attachments to...

  12. Shallow waters require platform innovation

    SciTech Connect

    Not Available

    1984-11-01

    Conventional platform designs generally apply to production facilities for relatively shallow-water oil and gas fields and consequently do not attract much attention in the offshore industry. But although new designs relate largely to deeper waters, specific requirements of a particular field in shallow water may well force designers to search for unconventional designs to meet a need for lower costs and rapid development. A central production facility is planned offshore at the drilling location AWG-1, approximately 3 km offshore and in a water depth of about six meters. The choice is governed by the optimum interfield pipeline configuration available at the AWG-1 location, taking into account the other locations required for adequate subsea well coverage. The platform is described.

  13. Sabellaria jeramae, a new species (Annelida: Polychaeta: Sabellariidae) from the shallow waters of Malaysia, with a note on the ecological traits of reefs.

    PubMed

    Nishi, Eijiroh; Matsuo, Kanako; Capa, Maria; Tomioka, Shinri; Kajihara, Hiroshi; Kupriyanova, Elena K; Polgar, Gianluca

    2015-12-07

    A new species of the genus Sabellaria Lamarck, 1818 (Annelida: Polychaeta: Sabellariidae) is described from the intertidal zone of Jeram, Selangor, Malaysia. Sabellaria jeramae n. sp. is a gregarious species that constructs large reefs several hundreds of meters long and 50-200 m wide. The new species is distinguished from other congeners by the character combination of the presence of a single kind of middle paleae with conspicuous morphology, and outer paleae with long frayed teeth. Morphological features of the species are described and compared to those of all congeneric species. We also compare the reef structure and geographical distribution of the new species to those of the members of the family Sabellariidae around the world, demonstrating the ecological traits of the reefs.

  14. Contrasting morphological and DNA barcode-suggested species boundaries among shallow-water amphipod fauna from the southern European Atlantic coast.

    PubMed

    Lobo, Jorge; Ferreira, Maria S; Antunes, Ilisa C; Teixeira, Marcos A L; Borges, Luisa M S; Sousa, Ronaldo; Gomes, Pedro A; Costa, Maria Helena; Cunha, Marina R; Costa, Filipe O

    2017-02-01

    In this study we compared DNA barcode-suggested species boundaries with morphology-based species identifications in the amphipod fauna of the southern European Atlantic coast. DNA sequences of the cytochrome c oxidase subunit I barcode region (COI-5P) were generated for 43 morphospecies (178 specimens) collected along the Portuguese coast which, together with publicly available COI-5P sequences, produced a final dataset comprising 68 morphospecies and 295 sequences. Seventy-five BINs (Barcode Index Numbers) were assigned to these morphospecies, of which 48 were concordant (i.e., 1 BIN = 1 species), 8 were taxonomically discordant, and 19 were singletons. Twelve species had matching sequences (<2% distance) with conspecifics from distant locations (e.g., North Sea). Seven morphospecies were assigned to multiple, and highly divergent, BINs, including specimens of Corophium multisetosum (18% divergence) and Dexamine spiniventris (16% divergence), which originated from sampling locations on the west coast of Portugal (only about 36 and 250 km apart, respectively). We also found deep divergence (4%-22%) among specimens of seven species from Portugal compared to those from the North Sea and Italy. The detection of evolutionarily meaningful divergence among populations of several amphipod species from southern Europe reinforces the need for a comprehensive re-assessment of the diversity of this faunal group.

  15. Distribution of sea urchins living near shallow water CO2 vents is dependent upon species acid-base and ion-regulatory abilities.

    PubMed

    Calosi, P; Rastrick, S P S; Graziano, M; Thomas, S C; Baggini, C; Carter, H A; Hall-Spencer, J M; Milazzo, M; Spicer, J I

    2013-08-30

    To reduce the negative effect of climate change on Biodiversity, the use of geological CO2 sequestration has been proposed; however leakage from underwater storages may represent a risk to marine life. As extracellular homeostasis is important in determining species' ability to cope with elevated CO2, we investigated the acid-base and ion regulatory responses, as well as the density, of sea urchins living around CO2 vents at Vulcano, Italy. We conducted in situ transplantation and field-based laboratory exposures to different pCO2/pH regimes. Our results confirm that sea urchins have some ability to regulate their extracellular fluid under elevated pCO2. Furthermore, we show that even in closely-related taxa divergent physiological capabilities underlie differences in taxa distribution around the CO2 vent. It is concluded that species distribution under the sort of elevated CO2 conditions occurring with leakages from geological storages and future ocean acidification scenarios, may partly be determined by quite subtle physiological differentiation.

  16. Shallow water sound propagation with surface waves.

    PubMed

    Tindle, Chris T; Deane, Grant B

    2005-05-01

    The theory of wavefront modeling in underwater acoustics is extended to allow rapid range dependence of the boundaries such as occurs in shallow water with surface waves. The theory allows for multiple reflections at surface and bottom as well as focusing and defocusing due to reflection from surface waves. The phase and amplitude of the field are calculated directly and used to model pulse propagation in the time domain. Pulse waveforms are obtained directly for all wavefront arrivals including both insonified and shadow regions near caustics. Calculated waveforms agree well with a reference solution and data obtained in a near-shore shallow water experiment with surface waves over a sloping bottom.

  17. Three-Dimensional Shallow Water Acoustics

    DTIC Science & Technology

    2016-03-30

    13-1-0026 entitled "Three- Dimensional Shallow Water Acoustics," Principal Investigator Dr. Ying-Tsong Lin. Sincerely, ;l1,J-Ju1𔃻 ~{hjM1...30/03/2016 01/01/2013-12/31/2015 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBERS Three-Dimensional Shallow Water Acoustics 5b, GRANT NUMBER N0001 4-13-1... Water Acoustics Dr. Ying-Tsong Lin Applied Ocean Physics and Engineering Department Woods Hole Oceanographic Institution, Woods Hole, MA 02543

  18. Surface Towed CSEM Systems for Shallow Water Mapping

    NASA Astrophysics Data System (ADS)

    Sherman, J.; Constable, S.; Kannberg, P. K.

    2015-12-01

    We have developed a low-power, surface towed electric dipole-dipole system suitable for mapping seafloor geology in shallow water and deployable from small boats. The transmitter is capable of up to 50 amps output using 12 VDC from a 110/240 VAC power supply, and can generate an arbitrary GPS stabilized ternary waveform. Transmitter antennas are typically 50 to 100 m long. Receivers are built around the standard Scripps seafloor electrode, amplifier, and logging systems but housed in floating PVC cases and equipped with GPS timing and positioning, pitch/roll/heading sensors, and accelerometers. Receiver dipoles are 1.5 m long rigid booms held 1 m below the surface. As with the Scripps deep-towed Vulcan system, rigid antennas are used to avoid noise associated with flexible antennas moving across Earth's magnetic field. The tow cable is a simple floating rope up to 1000 m long. Water depth and conductivity are sampled continuously in order to provide constraints for apparent resistivity calculations and inversion, and moored seafloor recorders can be used to extend transmitter/receiver offsets. The entire system can be air freighted and transported in one utility vehicle. We will present results from a study to map permafrost in shallow water off Prudhoe Bay, Alaska.

  19. Marine mammal audibility of selected shallow-water survey sources.

    PubMed

    MacGillivray, Alexander O; Racca, Roberto; Li, Zizheng

    2014-01-01

    Most attention about the acoustic effects of marine survey sound sources on marine mammals has focused on airgun arrays, with other common sources receiving less scrutiny. Sound levels above hearing threshold (sensation levels) were modeled for six marine mammal species and seven different survey sources in shallow water. The model indicated that odontocetes were most likely to hear sounds from mid-frequency sources (fishery, communication, and hydrographic systems), mysticetes from low-frequency sources (sub-bottom profiler and airguns), and pinnipeds from both mid- and low-frequency sources. High-frequency sources (side-scan and multibeam) generated the lowest estimated sensation levels for all marine mammal species groups.

  20. Review of factors affecting the distribution and abundance of waterfowl in shallow-water habitats of Chesapeake Bay

    USGS Publications Warehouse

    Perry, M.C.; Deller, A.S.

    1996-01-01

    Long-term trends of waterfowl populations in Chesapeake Bay demonstrate the importance of shallow-water habitats for waterfowl species. Although recent increases in field feeding by geese and swans lessened the importance of shallow-water areas for these species, most duck species depend almost exclusively on shallow-water habitats. Many factors influenced the distribution and abundance of waterfowl in shallow-water habitats. Habitat degradation resulted in the decline in numbers of most duck species and a change in distribution of some species. Increased numbers of mallards (Anas platyrhynchos) in recent decades probably resulted from release programs conducted by the Maryland Department of Natural Resources and private individuals. Studies of food habits since 1885 showed a decline in submerged-aquatic vegetation in the diet of some species, such as the canvasback (Aythya valisineria ), and an increase in the proportions of invertebrates in the diet. Diversity of food organisms for many waterfowl species has declined. Surveys of vegetation and invertebrates in the Chesapeake Bay generally reflect a degradation of shallow-water habitat. Human population increases in the Chesapeake Bay watershed directly and indirectly affected waterfowl distribution and abundance. The increase of exotic plant and invertebrate species in the bay, in most cases, benefited waterfowl populations. Increased contaminants have reduced the quality and quantity of habitat, although serious attempts to reverse this trend are underway. The use of shallow-water habitats by humans for fishing, hunting, boating, and other recreational and commercial uses reduced the use of shallow-water habitats by waterfowl. Humans can lessen the adverse influences on the valuable shallow-water habitats by restricting human population growth near these habitats and improving the water quality of the bay tributaries. Other affirmative actions that will improve these areas for waterfowl include greater

  1. Multigrid shallow water equations on an FPGA

    NASA Astrophysics Data System (ADS)

    Jeffress, Stephen; Duben, Peter; Palmer, Tim

    2015-04-01

    A novel computing technology for multigrid shallow water equations is investigated. As power consumption begins to constrain traditional supercomputing advances, weather and climate simulators are exploring alternative technologies that achieve efficiency gains through massively parallel and low power architectures. In recent years FPGA implementations of reduced complexity atmospheric models have shown accelerated speeds and reduced power consumption compared to multi-core CPU integrations. We continue this line of research by designing an FPGA dataflow engine for a mulitgrid version of the 2D shallow water equations. The multigrid algorithm couples grids of variable resolution to improve accuracy. We show that a significant reduction of precision in the floating point representation of the fine grid variables allows greater parallelism and thus improved overall peformance while maintaining accurate integrations. Preliminary designs have been constructed by software emulation. Results of the hardware implementation will be presented at the conference.

  2. Three-Dimensional Shallow Water Acoustics

    DTIC Science & Technology

    2015-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Three-Dimensional Shallow Water Acoustics Dr. Ying...model to predict acoustic fluctuations and derive sound pressure sensitivity kernels due to 3-D sound speed perturbation in the water column. The...numerical method to be utilized is a tangent linear solution to predict acoustic fluctuations due to 3-D sound speed perturbation in the water column. This

  3. Stochastic Modelling of Shallow Water Flows

    NASA Astrophysics Data System (ADS)

    Horritt, M. S.

    2002-05-01

    The application of computational fluid dynamics approaches to modelling shallow water flows in the environment is hindered by the uncertainty inherent to natural landforms, vegetation and processes. A stochastic approach to modelling is therefore required, but this has previously only been attempted through computationally intensive Monte Carlo methods. An efficient second order perturbation method is outlined in this presentation, whereby the governing equations are first discretised to form a non-linear system mapping model parameters to predictions. This system is then approximated using Taylor expansions to derive tractable expressions for the model prediction statistics. The approach is tested on a simple 1-D model of shallow water flow over uncertain topography, verified against ensembles of Monte Carlo simulations and approximate solutions derived by Fourier methods. Criteria for the applicability of increasing orders of Taylor expansions are derived as a function of flow depth and topographic variability. The results show that non-linear effects are important for even small topographic perturbations, and the second order perturbation method is required to derive model prediction statistics. This approximation holds well even as the flow depth tends towards the topographic roughness. The model predicted statistics are also well described by a Gaussian approximation, so only first and second moments need be calculated, even if these are significantly different to values predicted by a linear approximation. The implications for more sophisticated (2-D, advective etc.) models are discussed.

  4. Wave turbulence in shallow water models

    NASA Astrophysics Data System (ADS)

    Clark di Leoni, P.; Cobelli, P. J.; Mininni, P. D.

    2014-06-01

    We study wave turbulence in shallow water flows in numerical simulations using two different approximations: the shallow water model and the Boussinesq model with weak dispersion. The equations for both models were solved using periodic grids with up to 20482 points. In all simulations, the Froude number varies between 0.015 and 0.05, while the Reynolds number and level of dispersion are varied in a broader range to span different regimes. In all cases, most of the energy in the system remains in the waves, even after integrating the system for very long times. For shallow flows, nonlinear waves are nondispersive and the spectrum of potential energy is compatible with ˜k-2 scaling. For deeper (Boussinesq) flows, the nonlinear dispersion relation as directly measured from the wave and frequency spectrum (calculated independently) shows signatures of dispersion, and the spectrum of potential energy is compatible with predictions of weak turbulence theory, ˜k-4/3. In this latter case, the nonlinear dispersion relation differs from the linear one and has two branches, which we explain with a simple qualitative argument. Finally, we study probability density functions of the surface height and find that in all cases the distributions are asymmetric. The probability density function can be approximated by a skewed normal distribution as well as by a Tayfun distribution.

  5. Arc instability in shallow water wet welding

    SciTech Connect

    Nixon, J.H.; Graham, S.R.B.

    1993-12-31

    A series of wet welding trials, undertaken at Cranfield as part of a larger program, examined the relative stability of the process across a range of shallow water depths. The effect of welder skill, and the use of computer based data logging equipment, was also evaluated. By means of the data logging system, it was confirmed that welding carried out at a depth of 6 meters was markedly more stable than similar welds at 1.5 and 3 meters. Objective effects of welder skill were also noted, most markedly the ability of the skilled welder to operate at lower arc voltages and travel speeds. The use of the computer based data logging and analysis system was of great assistance in the program, and the use of similar equipment is highly recommended.

  6. Photosymbiosis and the expansion of shallow-water corals

    PubMed Central

    Frankowiak, Katarzyna; Wang, Xingchen T.; Sigman, Daniel M.; Gothmann, Anne M.; Kitahara, Marcelo V.; Mazur, Maciej; Meibom, Anders; Stolarski, Jarosław

    2016-01-01

    Roughly 240 million years ago (Ma), scleractinian corals rapidly expanded and diversified across shallow marine environments. The main driver behind this evolution is uncertain, but the ecological success of modern reef-building corals is attributed to their nutritional symbiosis with photosynthesizing dinoflagellate algae. We show that a suite of exceptionally preserved Late Triassic (ca. 212 Ma) coral skeletons from Antalya (Turkey) have microstructures, carbonate 13C/12C and 18O/16O, and intracrystalline skeletal organic matter 15N/14N all indicating symbiosis. This includes species with growth forms conventionally considered asymbiotic. The nitrogen isotopes further suggest that their Tethys Sea habitat was a nutrient-poor, low-productivity marine environment in which photosymbiosis would be highly advantageous. Thus, coral-dinoflagellate symbiosis was likely a key driver in the evolution and expansion of shallow-water scleractinians. PMID:27847868

  7. 78 FR 30242 - Fisheries of the Economic Exclusive Zone Off Alaska; Deep-Water Species Fishery by Vessels Using...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-22

    ... Exclusive Zone Off Alaska; Deep-Water Species Fishery by Vessels Using Trawl Gear in the Gulf of Alaska... comprise the deep-water species fishery by vessels using trawl gear in the Gulf of Alaska (GOA). This... specified for the deep-water species fishery in the GOA has been reached. DATES: Effective 1200...

  8. 75 FR 23189 - Fisheries of the Economic Exclusive Zone Off Alaska; Deep-Water Species Fishery by Vessels Using...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-03

    ... Exclusive Zone Off Alaska; Deep-Water Species Fishery by Vessels Using Trawl Gear in the Gulf of Alaska... comprise the deep-water species fishery by vessels using trawl gear in the Gulf of Alaska (GOA). This... prohibiting directed fishing for the deep-water species fishery by vessels using trawl gear in the GOA....

  9. 77 FR 46338 - Fisheries of the Economic Exclusive Zone Off Alaska; Deep-Water Species Fishery by Vessels Using...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-03

    ... Exclusive Zone Off Alaska; Deep-Water Species Fishery by Vessels Using Trawl Gear in the Gulf of Alaska... comprise the deep-water species fishery by vessels using trawl gear in the Gulf of Alaska (GOA). This..., NMFS is prohibiting directed fishing for the deep-water species fishery by vessels using trawl gear...

  10. 76 FR 23511 - Fisheries of the Economic Exclusive Zone Off Alaska; Deep-Water Species Fishery by Vessels Using...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-27

    ... Exclusive Zone Off Alaska; Deep-Water Species Fishery by Vessels Using Trawl Gear in the Gulf of Alaska... comprise the deep-water species fishery by vessels using trawl gear in the Gulf of Alaska (GOA). This... prohibiting directed fishing for the deep-water species fishery by vessels using trawl gear in the GOA....

  11. Species List of Alaskan Birds, Mammals, Fish, Amphibians, Reptiles, and Invertebrates. Alaska Region Report Number 82.

    ERIC Educational Resources Information Center

    Taylor, Tamra Faris

    This publication contains a detailed list of the birds, mammals, fish, amphibians, reptiles, and invertebrates found in Alaska. Part I lists the species by geographical regions. Part II lists the species by the ecological regions of the state. (CO)

  12. Shallow Water Bathymetry using the REMUS 100 Autonomous Underwater Vehicle

    DTIC Science & Technology

    2013-12-01

    UNCLASSIFIED UNCLASSIFIED Shallow Water Bathymetry using the REMUS 100 Autonomous Underwater Vehicle Michael Bell Maritime...2014 AR-015-799 December 2013 APPROVED FOR PUBLIC RELEASE UNCLASSIFIED UNCLASSIFIED Shallow Water Bathymetry using the REMUS 100...record position, depth and altitude enabling measurement of bathymetry along the vehicle track. The Defence Science and Technology Organisation

  13. Caribbean Shallow-water Black Corals (Cnidaria: Anthozoa: Antipatharia)

    SciTech Connect

    Opresko, Dennis M; Sanchez, Juan Armando

    2005-01-01

    Our aim is to provide a complete key and guide to the species of black corals from the Caribbean reefs at depths shallower than about 100 m. The key to the species is mostly based on colonial features that are recognized in the field, although some closely related species can only be differentiated by microscopic skeletal features. Each species is illustrated with one or more photos showing the size and shape of the colony; many photos were taken in the natural environment to facilitate underwater identification. Additionally, a short description is provided of each species and their microscopic diagnostic characters are illustrated with the aid of the Scanning Electron Microscope (SEM). Fifteen black coral species are found in relatively shallow-water in the Caribbean, Gulf of Mexico, and other parts of the tropical western Atlantic; these belong to the families Myriopathidae [Tanacetipathes hirta (Gray), T. tanacetum (Pourtales), T. barbadensis (Brook), T. thamnea (Warner), and Plumapathes pennacea (Pallas)]; Antipathidae [Antipathes lenta Pourtales, A. rubusifonnis Warner and Opresko, A. furcata Gray, A. umbratica Opresko, A. atlantica Gray, A. gracilis Gray, A. caribbeana Opresko, Stichopathes lutkeni Brook, and S. accidentalis (Gray)]; and Aphanipathidae [Rhipidipathes colombiana (Opresko and Sinchez)]. We hope that this guide will facilitate research on black corals on Caribbean reefs, where population surveys are urgently needed to evaluate or modify conservation policies.

  14. A modified siphon sampler for shallow water

    USGS Publications Warehouse

    Diehl, Timothy H.

    2008-01-01

    A modified siphon sampler (or 'single-stage sampler') was developed to sample shallow water at closely spaced vertical intervals. The modified design uses horizontal rather than vertical sample bottles. Previous siphon samplers are limited to water about 20 centimeters (cm) or more in depth; the modified design can sample water 10 cm deep. Several mounting options were used to deploy the modified siphon sampler in shallow bedrock streams of Middle Tennessee, while minimizing alteration of the stream bed. Sampling characteristics and limitations of the modified design are similar to those of the original design. Testing showed that the modified sampler collects unbiased samples of suspended silt and clay. Similarity of the intake to the original siphon sampler suggests that the modified sampler would probably take downward-biased samples of suspended sand. Like other siphon samplers, it does not sample isokinetically, and the efficiency of sand sampling can be expected to change with flow velocity. The sampler needs to be located in the main flow of the stream, and is subject to damage from rapid flow and floating debris. Water traps were added to the air vents to detect the flow of water through the sampler, which can cause a strong upward bias in sampled suspended-sediment concentration. Water did flow through the sampler, in some cases even when the top of the air vent remained above water. Air vents need to be extended well above maximum water level to prevent flow through the sampler.

  15. Groundwater Recharge in Sandy Shallow Water Aquifers

    NASA Astrophysics Data System (ADS)

    Jaber, F. H.; Shukla, S.

    2015-12-01

    In shallow table conditions, a disproportionate increase or decrease in water table in response to minor water input or drainage is observed. This increase happens because the capillary fringe of the shallow water table reaches up to or near the surface (Wieringermeer effect). Conventional methods of calculating recharge such as multiplying the actual specific yield with the water table fluctuations cannot be used for Wieringermeer effect situations. A method using water balance data and soil moisture at different depths in the lysimeters was developed to estimate recharge and upflux. The recharge results were used to develop the apparent specific yield (Sya), which could be used to calculate consequent recharge events from water table fluctuations data. The correlations between water table level changes and rainfall, seepage irrigation, drip irrigation, and drainage were analyzed. Correlations with rainfall, seepage irrigation, and drainage were satisfactory (R-square ranged from 0.46 to 0.97). Combining the water tables fluctuations relationships developed with Sya value will allow the prediction of recharge from rainfall and irrigation events without the need for soil moisture equipment.

  16. Polarization Lidar for Shallow Water Depth Measurement

    NASA Astrophysics Data System (ADS)

    Mitchell, S.; Thayer, J. P.

    2011-12-01

    A bathymetric, polarization lidar system transmitting at 532 nanometers is developed for applications of shallow water depth measurement. The technique exploits polarization attributes of the probed water body to isolate surface and floor returns, enabling constant fraction detection schemes to determine depth. The minimum resolvable water depth is no longer dictated by the system's laser or detector pulse width and can achieve better than an order of magnitude improvement over current water depth determination techniques. In laboratory tests, a Nd:YAG microchip laser coupled with polarization optics, a single photomultiplier tube, a constant fraction discriminator and a time to digital converter are used to target various water depths. Measurement of 1 centimeter water depths with an uncertainty of ±3 millimeters are demonstrated using the technique. Additionally, a dual detection channel version of the lidar system is in development, permitting simultaneous measurement of co- and cross-polarized signals scattered from the target water body. This novel approach enables new approaches to designing laser bathymetry systems for shallow depth determination from remote platforms while not compromising deep water depth measurement, supporting comprehensive hydrodynamic studies.

  17. Shallow water model for horizontal centrifugal casting

    NASA Astrophysics Data System (ADS)

    Boháček, J.; Kharicha, A.; Ludwig, A.; Wu, M.

    2012-07-01

    A numerical model was proposed to simulate the solidification process of an outer shell of work roll made by the horizontal centrifugal casting technique. Shallow water model was adopted to solve the 2D average flow dynamics of melt spreading and the average temperature distribution inside the centrifugal casting mould by considering the centrifugal force, Coriolis force, viscous force due to zero velocity on the mould wall, gravity, and energy transport by the flow. Additionally, a 1D sub-model was implemented to consider the heat transfer in the radial direction from the solidifying shell to the mould. The solidification front was tracked by fulfilling the Stefan condition. Radiative and convective heat losses were included from both, the free liquid surface and the outer wall of the mould. Several cases were simulated with the following assumed initial conditions: constant height of the liquid metal (10, 20, and 30 mm), uniform temperature of the free liquid surface (1755 K). The simulation results have shown that while the solidification front remained rather flat, the free surface was disturbed by waves. The amplitude of waves increased with the liquid height. Free surface waves diminished as the solidification proceeded.

  18. Combined effects of climate change and bank stabilization on shallow water habitats of chinook salmon.

    PubMed

    Jorgensen, Jeffrey C; McClure, Michelle M; Sheer, Mindi B; Munn, Nancy L

    2013-12-01

    Significant challenges remain in the ability to estimate habitat change under the combined effects of natural variability, climate change, and human activity. We examined anticipated effects on shallow water over low-sloped beaches to these combined effects in the lower Willamette River, Oregon, an area highly altered by development. A proposal to stabilize some shoreline with large rocks (riprap) would alter shallow water areas, an important habitat for threatened Chinook salmon (Oncorhynchus tshawytscha), and would be subject to U.S. Endangered Species Act-mandated oversight. In the mainstem, subyearling Chinook salmon appear to preferentially occupy these areas, which fluctuate with river stages. We estimated effects with a geospatial model and projections of future river flows. Recent (1999-2009) median river stages during peak subyearling occupancy (April-June) maximized beach shallow water area in the lower mainstem. Upstream shallow water area was maximized at lower river stages than have occurred recently. Higher river stages in April-June, resulting from increased flows predicted for the 2080s, decreased beach shallow water area 17-32%. On the basis of projected 2080s flows, more than 15% of beach shallow water area was displaced by the riprap. Beach shallow water area lost to riprap represented up to 1.6% of the total from the mouth to 12.9 km upstream. Reductions in shallow water area could restrict salmon feeding, resting, and refuge from predators and potentially reduce opportunities for the expression of the full range of life-history strategies. Although climate change analyses provided useful information, detailed analyses are prohibitive at the project scale for the multitude of small projects reviewed annually. The benefits of our approach to resource managers include a wider geographic context for reviewing similar small projects in concert with climate change, an approach to analyze cumulative effects of similar actions, and estimation of the

  19. HF Radar Sea-echo from Shallow Water.

    PubMed

    Lipa, Belinda; Nyden, Bruce; Barrick, Don; Kohut, Josh

    2008-08-06

    HF radar systems are widely and routinely used for the measurement of ocean surface currents and waves. Analysis methods presently in use are based on the assumption of infinite water depth, and may therefore be inadequate close to shore where the radar echo is strongest. In this paper, we treat the situation when the radar echo is returned from ocean waves that interact with the ocean floor. Simulations are described which demonstrate the effect of shallow water on radar sea-echo. These are used to investigate limits on the existing theory and to define water depths at which shallow-water effects become significant. The second-order spectral energy increases relative to the first-order as the water depth decreases, resulting in spectral saturation when the waveheight exceeds a limit defined by the radar transmit frequency. This effect is particularly marked for lower radar transmit frequencies. The saturation limit on waveheight is less for shallow water. Shallow water affects second-order spectra (which gives wave information) far more than first-order (which gives information on current velocities), the latter being significantly affected only for the lowest radar transmit frequencies for extremely shallow water. We describe analysis of radar echo from shallow water measured by a Rutgers University HF radar system to give ocean wave spectral estimates. Radar-derived wave height, period and direction are compared with simultaneous shallow-water in-situ measurements.

  20. Shallow Water Optical Water Quality Buoy

    NASA Technical Reports Server (NTRS)

    Bostater, Charles

    1998-01-01

    This NASA grant was funded as a result of an unsolicited proposal submission to Kennedy Space Center. The proposal proposed the development and testing of a shallow water optical water quality buoy. The buoy is meant to work in shallow aquatic systems (ponds, rivers, lagoons, and semi-enclosed water areas where strong wind wave action is not a major environmental During the project period of three years, a demonstration of the buoy was conducted. The last demonstration during the project period was held in November, 1996 when the buoy was demonstrated as being totally operational with no tethered communications line. During the last year of the project the buoy was made to be solar operated by large gel cell batteries. Fund limitations did not permit the batteries in metal enclosures as hoped for higher wind conditions, however the system used to date has worked continuously for in- situ operation of over 18 months continuous deployment. The system needs to have maintenance and somewhat continuous operational attention since various components have limited lifetime ages. For example, within the last six months the onboard computer has had to be repaired as it did approximately 6 months after deployment. The spectrograph had to be repaired and costs for repairs was covered by KB Science since no ftmds were available for this purpose after the grant expired. Most recently the computer web page server failed and it is currently being repaired by KB Science. In addition, the cell phone operation is currently being ftmded by Dr. Bostater in order to maintain the system's operation. The above points need to be made to allow NASA to understand that like any sophisticated measuring system in a lab or in the field, necessary funding and maintenance is needed to insure the system's operational state and to obtain quality factor. The proposal stated that the project was based upon the integration of a proprietary and confidential sensor and probe design that was developed by

  1. Indicators: Shallow Water Habitat/In-stream Fish Habitat

    EPA Pesticide Factsheets

    Shallow water habitat, also referred to as in-stream fish habitat, refers to areas that fish and other aquatic organisms need for concealment, breeding and feeding. This includes large woody snags, boulders, rock ledges, and undercut banks.

  2. Shallow Water UXO Technology Demonstration Site Scoring Record No. 7

    DTIC Science & Technology

    2007-05-01

    to eat lunch and charge the battery – using the truck instead of the trickle charger . Downtime equipment 85 1425 1450 Surveying. Collecting data...sensor array designed by 3DGeophysics. Testing was conducted at ATC, Standardized Shallow Water UXO Technology Demonstration Site. A description of...available on the capabilities of shallow water detection systems when these criteria were developed. However, they were used in the design of the test

  3. Fluctuations of Broadband Acoustic Signals in Shallow Water

    DTIC Science & Technology

    2015-09-30

    Signals in Shallow Water Mohsen Badiey College of Earth, Ocean, and Environment University of Delaware Newark, DE 19716 Phone: (302) 831-3687 Fax...refraction, and scattering in shallow water and coastal regions in the presence of temporal and spatial ocean variability. OBJECTIVES The scientific...of water column and dynamic sea surface variability, as well as source/receiver motion on acoustic wave propagation for underwater acoustic

  4. New records for the shallow-water chiton fauna (Mollusca, Polyplacophora) of the Azores (NE Atlantic).

    PubMed

    Avila, Sérgio P; Sigwart, Julia

    2013-01-01

    Published records, original data from recent field work on all of the islands of the Azores (NE Atlantic), and a revision of the entire mollusc collection deposited in the Department of Biology of the University of the Azores (DBUA) were used to compile a checklist of the shallow-water Polyplacophora of the Azores. Lepidochitona cf. canariensis and Tonicella rubra are reported for the first time for this archipelago, increasing the recorded Azorean fauna to seven species.

  5. Estimation of freak wave occurrence in shallow water regions

    NASA Astrophysics Data System (ADS)

    Kashima, Hiroaki

    2014-05-01

    In the last two decades, freak waves have become an important topic in engineering and science and are sometimes featured by a single and steep crest causing severe damage to offshore structures and vessels. An accurate estimation of maximum wave height and prediction of freak wave occurrence frequency is important for marine safety and ocean developments. According to several studies on freak waves, the deep-water third-order nonlinearity (quasi-resonant four-wave interactions) can lead to a significant enhancement of freak wave occurrence from normality. However, it is not clear the behavior of offshore generated freak waves shoaling to shallow water regions. In general, a numerical simulation based on Boussinesq model has been frequently and widely used to estimate wave transformation in shallow water regions and has high-level performance in the design of coast and harbor structures in Japan. However, it is difficult to describe the freak wave occurrence from deep to shallow water regions by the Boussinesq model because it can express only up to the second-order nonlinear interactions. There is a gap of governing equation between deep and shallow water regions from the extreme wave modeling point of view. It is necessary to investigate the aftereffects of generated freak waves by the third-order nonlinear interactions in deep water regions and their propagation to shallow water regions using the Boussinesq model. In this study, the model experiments in a wave tank and numerical simulations based on the Boussinesq model were conducted to estimate the freak wave occurrence from deep to shallow water regions. In the model experiments, the maximum wave height increases with an increase in kurtosis by the third-order nonlinear interactions in deep water regions. The dependence of kurtosis on freak wave occurrence weakens by the second-order nonlinear interactions associated with wave shoaling if dimensionless water depth kph becomes shallower than 1.363, which kp

  6. 75 FR 38937 - Fisheries of the Economic Exclusive Zone Off Alaska; Deep-Water Species Fishery by Catcher...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-07

    ... Exclusive Zone Off Alaska; Deep-Water Species Fishery by Catcher Vessels in the Gulf of Alaska AGENCY... the deep-water species fishery for catcher vessels subject to sideboard limits established under the... Pacific halibut prohibited species catch (PSC) sideboard limit specified for the deep-water...

  7. 76 FR 39790 - Fisheries of the Economic Exclusive Zone Off Alaska; Deep-Water Species Fishery by Catcher...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-07

    ... Exclusive Zone Off Alaska; Deep-Water Species Fishery by Catcher Vessels in the Gulf of Alaska AGENCY... the deep-water species fishery for catcher vessels subject to sideboard limits established under the... Pacific halibut prohibited species catch (PSC) sideboard limit specified for the deep-water...

  8. A Review of the Prediction of Squat in Shallow Water

    NASA Astrophysics Data System (ADS)

    Millward, A.

    Recent evidence has shown that the effect of a ship moving in shallow water and the resultant squat are not well understood. This paper reviews the general problem of a ship in shallow water and illustrates the corresponding resistance, trim and sinkage at both sub-critical and also at super-critical speeds.The paper then reviews the various methods of predicting the squat of a ship in shallow water in the sub-critical range, which is applicable to most ships. It is suggested that the simple rule-of-thumb methods are, at best, unreliable and the paper gives examples of empirical methods which have been tested against various sets of data and seem to give more representative answers. A summary of the notation used is given at the end of the paper.

  9. 77 FR 20339 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-04

    ... species complexes: the shallow-water and the deep-water fishery species complexes. A shallow-water halibut PSC sideboard limit restricts the catch of halibut PSC in the shallow-water fishery complex, which includes pollock, Pacific cod, shallow-water flatfish, flathead sole, Atka mackerel, and ``other...

  10. Alaska

    SciTech Connect

    Jones, B.C.; Sears, D.W.

    1981-10-01

    Twenty-five exploratory wells were drilled in Alaska in 1980. Five oil or gas discovery wells were drilled on the North Slope. One hundred and seventeen development and service wells were drilled and completed, primarily in the Prudhoe Bay and Kuparuk River fields on the North Slope. Geologic-geophysical field activity consisted of 115.74 crew months, an increase of almost 50% compared to 1979. These increases affected most of the major basins of the state as industry stepped up preparations for future lease sales. Federal acreage under lease increased slightly, while state lease acreage showed a slight decline. The year's oil production showed a increase of 16%, while gas production was down slightly. The federal land freeze in Alaska showed signs of thawing, as the US Department of Interior asked industry to identify areas of interest onshore for possible future leasing. National Petroleum Reserve in Alaska was opened to private exploration, and petroleum potential of the Arctic Wildlife Refuge will be studied. One outer continental shelf lease sale was held in the eastern Gulf of Alaska, and a series of state and federal lease sales were announced for the next 5 years. 5 figures, 5 tables.

  11. Linear and nonlinear dynamics of longshore currents in shallow water

    NASA Astrophysics Data System (ADS)

    Li, Ye; Choi, Wooyoung

    2003-11-01

    The linear instability of shear flows in shallow water has been extensively studied under the rigid-lid assumption and has been known to play an important role on the dynamics of longshore currents, after the work by Bowen & Holman (1989). Here both analytical and numerical studies on the linear instability of various longshore currents are carried out and special attentions are paid to the effect of free surface on unstable currents. The full shallow water equations are then solved numerically to further describe the evolution of unstable shear waves beyond the linear regime.

  12. Alaska

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Though it's not quite spring, waters in the Gulf of Alaska (right) appear to be blooming with plant life in this true-color MODIS image from March 4, 2002. East of the Alaska Peninsula (bottom center), blue-green swirls surround Kodiak Island. These colors are the result of light reflecting off chlorophyll and other pigments in tiny marine plants called phytoplankton. The bloom extends southward and clear dividing line can be seen west to east, where the bloom disappears over the deeper waters of the Aleutian Trench. North in Cook Inlet, large amounts of red clay sediment are turning the water brown. To the east, more colorful swirls stretch out from Prince William Sound, and may be a mixture of clay sediment from the Copper River and phytoplankton. Arcing across the top left of the image, the snow-covered Brooks Range towers over Alaska's North Slope. Frozen rivers trace white ribbons across the winter landscape. The mighty Yukon River traverses the entire state, beginning at the right edge of the image (a little way down from the top) running all the way over to the Bering Sea, still locked in ice. In the high-resolution image, the circular, snow-filled calderas of two volcanoes are apparent along the Alaska Peninsula. In Bristol Bay (to the west of the Peninsula) and in a couple of the semi-clear areas in the Bering Sea, it appears that there may be an ice algae bloom along the sharp ice edge (see high resolution image for better details). Ground-based observations from the area have revealed that an under-ice bloom often starts as early as February in this region and then seeds the more typical spring bloom later in the season.

  13. Shallow Water Reverberation and Low Frequency Seabed Scattering

    DTIC Science & Technology

    2012-09-30

    Analytical method of angular power spectrum, range and depth structure of the echo-to-reverberation ratio in shallow water Sound Field,” (Chinese) ACTA ... ACUSTICA , 5 (2), 86-99 (1980). 2. D.R. Jackson and M.D. Richardson, <High-frequency Seafloor Acoustics>, 616 pages, Springer, 2007. 3. J.X. Zhou, X.Z

  14. Onboard Prediction of Propagation Loss in Shallow Water

    DTIC Science & Technology

    1981-09-16

    substrate roughn*p, (4) modal coupling, and (6) biologia scAtterers;,6. Grain asiz distribution Is not an adequate predctor of acoustical properties; heuce...INTRODUCTION ......................................... 1 GENERAL COMMENTS ................................... 2 SEDIMENT SOUND SPEED AND DENSITY...for an onboard perfor- mance prediction capability in shallow water. There is a general requirement for an onboard performance prediction capability

  15. Computing nonhydrostatic shallow-water flow over steep terrain

    USGS Publications Warehouse

    Denlinger, R.P.; O'Connell, D. R. H.

    2008-01-01

    Flood and dambreak hazards are not limited to moderate terrain, yet most shallow-water models assume that flow occurs over gentle slopes. Shallow-water flow over rugged or steep terrain often generates significant nonhydrostatic pressures, violating the assumption of hydrostatic pressure made in most shallow-water codes. In this paper, we adapt a previously published nonhydrostatic granular flow model to simulate shallow-water flow, and we solve conservation equations using a finite volume approach and an Harten, Lax, Van Leer, and Einfeldt approximate Riemann solver that is modified for a sloping bed and transient wetting and drying conditions. To simulate bed friction, we use the law of the wall. We test the model by comparison with an analytical solution and with results of experiments in flumes that have steep (31??) or shallow (0.3??) slopes. The law of the wall provides an accurate prediction of the effect of bed roughness on mean flow velocity over two orders of magnitude of bed roughness. Our nonhydrostatic, law-of-the-wall flow simulation accurately reproduces flume measurements of front propagation speed, flow depth, and bed-shear stress for conditions of large bed roughness. ?? 2008 ASCE.

  16. Shallow water table depth algorithm in SWAT: Recent developments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Knowledge of the shallow water table depth (wtd) is crucial in many studies including determination of optimum irrigation and drainage management systems for agricultural production, farm machine trafficability, and water quality due to agricultural chemical transport and soil salinity. Therefore, i...

  17. Fluctuations of Broadband Acoustic Signals in Shallow Water

    DTIC Science & Technology

    2010-09-30

    DISTRIBUTION STATEMENT A: Distribution approved...for public release; distribution is unlimited. Fluctuations of Broadband Acoustic Signals in Shallow Water Mohsen Badiey College of Earth, Ocean...AND ADDRESS(ES) 10. SPONSOR/MONITOR’S ACRONYM(S) 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 12. DISTRIBUTION /AVAILABILITY STATEMENT Approved for

  18. Shallow water modeling of Antarctic Bottom Water crossing the equator

    NASA Astrophysics Data System (ADS)

    Choboter, Paul F.; Swaters, Gordon E.

    2004-03-01

    The dynamics of abyssal equator-crossing flows are examined by studying simplified models of the flow in the equatorial region in the context of reduced-gravity shallow water theory. A simple "frictional geostrophic" model for one-layer cross-equatorial flow is described, in which geostrophy is replaced at the equator by frictional flow down the pressure gradient. This model is compared via numerical simulations to the one-layer reduced-gravity shallow water model for flow over realistic equatorial Atlantic Ocean bottom topography. It is argued that nonlinear advection is important at key locations where it permits the current to flow against a pressure gradient, a mechanism absent in the frictional geostrophic model and one of the reasons this model predicts less cross-equatorial flow than the shallow water model under similar conditions. Simulations of the shallow water model with an annually varying mass source reproduce the correct amplitude of observed time variability of cross-equatorial flow. The time evolution of volume transport across specific locations suggests that mass is stored in an equatorial basin, which can reduce the amplitude of time dependence of fluid actually proceeding into the Northern Hemisphere as compared to the amount entering the equatorial basin. Observed time series of temperature data at the equator are shown to be consistent with this hypothesis.

  19. Sediment Transport at Density Fronts in Shallow Water

    DTIC Science & Technology

    2012-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Sediment Transport at Density Fronts in Shallow Water...tidal inundation cycle as it travels across the intertidal zone, and - combine the observations and model results to (1) quantify sediment suspension...S) 12. DISTRIBUTION /AVAILABILITY STATEMENT Approved for public release, distribution unlimited 13. SUPPLEMENTARY NOTES The original document

  20. Thermal shallow water models of geostrophic turbulence in Jovian atmospheres

    SciTech Connect

    Warneford, Emma S. Dellar, Paul J.

    2014-01-15

    Conventional shallow water theory successfully reproduces many key features of the Jovian atmosphere: a mixture of coherent vortices and stable, large-scale, zonal jets whose amplitude decreases with distance from the equator. However, both freely decaying and forced-dissipative simulations of the shallow water equations in Jovian parameter regimes invariably yield retrograde equatorial jets, while Jupiter itself has a strong prograde equatorial jet. Simulations by Scott and Polvani [“Equatorial superrotation in shallow atmospheres,” Geophys. Res. Lett. 35, L24202 (2008)] have produced prograde equatorial jets through the addition of a model for radiative relaxation in the shallow water height equation. However, their model does not conserve mass or momentum in the active layer, and produces mid-latitude jets much weaker than the equatorial jet. We present the thermal shallow water equations as an alternative model for Jovian atmospheres. These equations permit horizontal variations in the thermodynamic properties of the fluid within the active layer. We incorporate a radiative relaxation term in the separate temperature equation, leaving the mass and momentum conservation equations untouched. Simulations of this model in the Jovian regime yield a strong prograde equatorial jet, and larger amplitude mid-latitude jets than the Scott and Polvani model. For both models, the slope of the non-zonal energy spectra is consistent with the classic Kolmogorov scaling, and the slope of the zonal energy spectra is consistent with the much steeper spectrum observed for Jupiter. We also perform simulations of the thermal shallow water equations for Neptunian parameter values, with a radiative relaxation time scale calculated for the same 25 mbar pressure level we used for Jupiter. These Neptunian simulations reproduce the broad, retrograde equatorial jet and prograde mid-latitude jets seen in observations. The much longer radiative time scale for the colder planet Neptune

  1. Source rock potential of shallow-water evaporitic settings

    SciTech Connect

    Warren, J.K.

    1986-05-01

    In the major evaporitic environments on the world's surface today, most organic matter accumulates in shallow subaqueous to seasonally subaerially exposed, algal-mat sediments. Given the present depositional setting, this organic matter probably could not be preserved to form source rocks. However, if the authors place such evaporite deposition into a geologic context, source rocks could have formed in shallow-water settings in the past. Such settings were characterized by hydrologic conditions that allowed the retention of hypersaline, anoxic pore water to depths where the organic material was buried deep enough to generate hydrocarbons. When deep-basin, shallow-water, evaporite successions were laid down in basins such as the Mediterranean during the late Miocene, the Michigan basin during the Silurian, and in other large saline giants, conditions were right for source rocks to form within shallow-water and salt-flat evaporitic environments. The evaporites in these saline giants were deposited under conditions of relatively shallow water (< 50 m); the basin never appears to have dried out, but water levels changed quickly (approx. 10,000 years) from shallow to deep. Continual water saturation coupled with saline pore fluids prevented the inflow of fresh, oxidizing ground water into the basin center of shallow-water organic-rich evaporites. Immature hydrocarbons derived from such rocks today drip from the 5.5-m.y. old evaporites of Sicily in active salt and sulfur mines. Organic-rich sediments could also be preserved to generate hydrocarbons in rapidly subsiding rift basins. In such basins, rapid burial has prevented the entrance of fresher oxygenated waters and the associated degradation and destruction of the organic matter. The early continental rift stage generates the source rocks; the ephemeral streams, wadis, and dune fields become the reservoirs, and the subsequent evaporite stage seals the reservoir.

  2. Critical fishery species in Alaska offshore oil and gas lease areas

    SciTech Connect

    Arbegast, J.; Allen, M.

    1980-11-01

    Offshore oil and gas development in Alaska is governed through sales of lease blocks in designated areas. USBLM manages these sales and prepares the necessary environmental impact statement prior to each sale. Collected fishery data are tabulated, linking critical crustacean and fishery species with their associated lease areas. Listed are critical species, organized by taxonomic name, associated common name, and taxonomic code numbers. Each critical species is linked to one or more of the lease area numbers, derived from USBLM planning units.

  3. Bumble bees (Hymenoptera: Apidae: Bombus spp.) of interior Alaska: Species composition, distribution, seasonal biology, and parasites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Despite the ecological and agricultural significance of bumble bees in Alaska, very little is known and published about this important group at the regional level. The objectives of this study were to provide baseline data on species composition, distribution, seasonal biology, and parasites of the ...

  4. Moose as a vector for non-indigenous plant species in Alaska

    Technology Transfer Automated Retrieval System (TEKTRAN)

    White sweetclover and narrowleaf hawksbeard are non-indigenous invasive plant species in Alaska that are rapidly spreading, including into areas that are otherwise free of non-indigenous plants. There has been concern that native moose could be dispersing viable seed from these plants after ingestio...

  5. Shallow-water System Dynamics in Chesapeake Bay, with Physical-Biological Modeling Application

    NASA Astrophysics Data System (ADS)

    Tian, R.; Wang, P.; Linker, L. C.

    2014-12-01

    Chesapeake Bay is the largest estuary in the United States. The total surface area is 9920 square kilometers of which 7540 square kilometers are shallower than 10 m. These shallow systems provide vital habitats and nursery grounds for numerous species of fish, shellfish, and wildlife. In the Chesapeake the shallow water systems have deteriorated in terms of healthy ecosystem levels and submerged aquatic vegetation (SAV). Restoration of the shallow water systems requires an understanding of their dynamics including wave-current interactions, shoreline erosion, sediment suspension, biological and biogeochemical processes, sediment diagenesis, sediment-water exchange, and diel cycles of temperature, salinity, turbidity, alkalinity, chlorophyll, nutrients, and dissolved oxygen (DO). To this end, an extensive shallow water monitoring program has been implemented in the Chesapeake since 2003. The program includes bi-weekly cruises of nutrient sampling, a continuous monitoring network with electronic sensors collecting data at a 15 minute interval, and a unique data flow survey from moving boats that collect underway observations with a datum frequency of seconds. The data reveal large diel cycles, with chlorophyll varying between a few mg/l to hundreds of mg/l, DO between 0 to 20 mg/l (with saturation from 0 to 250%), turbidity between 0 to 1500 NTUs, and pH from 6.0 to 9.5, which demonstrate the highly dynamic nature in physical and biological process of the shallow water systems . In order to better understand the key mechanisms and processes of these shallow-water systems and to explore the monitoring data, we applied a coupled physical and water quality model to the Chester and Corsica tributaries. The physical model is the Unstructured Finite Volume Coastal Ocean Model (FVCOM) and the water quality model is the Integrated Compartment Model (ICM) which has 36 state variables such as phytoplankton, zooplankton, DO, nutrients, and various organic matter and sediment

  6. Wind wave prediction in shallow water: Theory and applications

    SciTech Connect

    Cavaleri, L.; Rizzoli, P.M.

    1981-11-20

    A wind wave forecasting model is described, based upon the ray technique, which is specifically designed for shallow water areas. The model explicitly includes wave generation, refraction, and shoaling, while nonlinear dissipative processes (breaking and bottom fricton) are introduced through a suitable parametrization. The forecast is provided at a specified time and target position, in terms of a directional spectrum, from which the one-dimensional spectrum and the significant wave height are derived. The model has been used to hindcast storms both in shallow water (Northern Adriatic Sea) and in deep water conditions (Tyrrhenian Sea). The results have been compared with local measurements, and the rms error for the significant wave height is between 10 and 20%. A major problems has been found in the correct evaluation of the wind field.

  7. GPU Accelerated Discontinuous Galerkin Methods for Shallow Water Equations

    NASA Astrophysics Data System (ADS)

    Gandham, Rajesh; Medina, David; Warburton, Timothy

    2015-07-01

    We discuss the development, verification, and performance of a GPU accelerated discontinuous Galerkin method for the solutions of two dimensional nonlinear shallow water equations. The shallow water equations are hyperbolic partial differential equations and are widely used in the simulation of tsunami wave propagations. Our algorithms are tailored to take advantage of the single instruction multiple data (SIMD) architecture of graphic processing units. The time integration is accelerated by local time stepping based on a multi-rate Adams-Bashforth scheme. A total variational bounded limiter is adopted for nonlinear stability of the numerical scheme. This limiter is coupled with a mass and momentum conserving positivity preserving limiter for the special treatment of a dry or partially wet element in the triangulation. Accuracy, robustness and performance are demonstrated with the aid of test cases. We compare the performance of the kernels expressed in a portable threading language OCCA, when cross compiled with OpenCL, CUDA, and OpenMP at runtime.

  8. A semi-Lagrangian approach to the shallow water equation

    NASA Technical Reports Server (NTRS)

    Bates, J. R.; Mccormick, Stephen F.; Ruge, John; Sholl, David S.; Yavneh, Irad

    1993-01-01

    We present a formulation of the shallow water equations that emphasizes the conservation of potential vorticity. A locally conservative semi-Lagrangian time-stepping scheme is developed, which leads to a system of three coupled PDE's to be solved at each time level. We describe a smoothing analysis of these equations, on which an effective multigrid solver is constructed. Some results from applying this solver to the static version of these equations are presented.

  9. Validation of Numerical Shallow Water Models for Tidal Lagoons

    SciTech Connect

    Eliason, D.; Bourgeois, A.

    1999-11-01

    An analytical solution is presented for the case of a stratified, tidally forced lagoon. This solution, especially its energetics, is useful for the validation of numerical shallow water models under stratified, tidally forced conditions. The utility of the analytical solution for validation is demonstrated for a simple finite difference numerical model. A comparison is presented of the energetics of the numerical and analytical solutions in terms of the convergence of model results to the analytical solution with increasing spatial and temporal resolution.

  10. Modeling of Mid-Frequency Reverberation in Very Shallow Water

    DTIC Science & Technology

    2014-09-30

    reverberation at mid frequencies for a wide variety of sea bed types. In particular, they are primary tools used in the Ocean Bottom Characterization...1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Modeling of Mid -Frequency Reverberation in Very Shallow...research is to develop a mid -frequency shallow-water reverberation model relevant to specific conditions (1 – 10 kHz, ~20 m water depth, ~ 5 km range) of

  11. Mixing and shocks in geophysical shallow water models

    NASA Astrophysics Data System (ADS)

    Jacobson, Tivon

    In the first section, a reduced two-layer shallow water model for fluid mixing is described. The model is a nonlinear hyperbolic quasilinear system of partial differential equations, derived by taking the limit as the upper layer becomes infinitely deep. It resembles the shallow water equations, but with an active buoyancy. Fluid entrainment is supposed to occur from the upper layer to the lower. Several physically motivated closures are proposed, including a robust closure based on maximizing a mixing entropy (also defined and derived) at shocks. The structure of shock solutions is examined. The Riemann problem is solved by setting the shock speed to maximize the production of mixing entropy. Shock-resolving finite-volume numerical models are presented with and without topographic forcing. Explicit shock tracking is required for strong shocks. The constraint that turbulent energy production be positive is considered. The model has geophysical applications in studying the dynamics of dense sill overflows in the ocean. The second section discusses stationary shocks of the shallow water equations in a reentrant rotating channel with wind stress and topography. Asymptotic predictions for the shock location, strength, and associated energy dissipation are developed by taking the topographic perturbation to be small. The scaling arguments for the asymptotics are developed by demanding integrated energy and momentum balance, with the result that the free surface perturbation is of the order of the square root of the topographic perturbation. Shock formation requires that linear waves be nondispersive, which sets a solvability condition on the mean flow and which leads to a class of generalized Kelvin waves. Two-dimensional shock-resolving numerical simulations validate the asymptotic expressions and demonstrate the presence of stationary separated flow shocks in some cases. Geophysical applications are considered. Overview sections on shock-resolving numerical methods

  12. Shallow water equations: viscous solutions and inviscid limit

    NASA Astrophysics Data System (ADS)

    Chen, Gui-Qiang; Perepelitsa, Mikhail

    2012-12-01

    We establish the inviscid limit of the viscous shallow water equations to the Saint-Venant system. For the viscous equations, the viscosity terms are more degenerate when the shallow water is close to the bottom, in comparison with the classical Navier-Stokes equations for barotropic gases; thus, the analysis in our earlier work for the classical Navier-Stokes equations does not apply directly, which require new estimates to deal with the additional degeneracy. We first introduce a notion of entropy solutions to the viscous shallow water equations and develop an approach to establish the global existence of such solutions and their uniform energy-type estimates with respect to the viscosity coefficient. These uniform estimates yield the existence of measure-valued solutions to the Saint-Venant system generated by the viscous solutions. Based on the uniform energy-type estimates and the features of the Saint-Venant system, we further establish that the entropy dissipation measures of the viscous solutions for weak entropy-entropy flux pairs, generated by compactly supported C 2 test-functions, are confined in a compact set in H -1, which yields that the measure-valued solutions are confined by the Tartar-Murat commutator relation. Then, the reduction theorem established in Chen and Perepelitsa [5] for the measure-valued solutions with unbounded support leads to the convergence of the viscous solutions to a finite-energy entropy solution of the Saint-Venant system with finite-energy initial data, which is relative with respect to the different end-states of the bottom topography of the shallow water at infinity. The analysis also applies to the inviscid limit problem for the Saint-Venant system in the presence of friction.

  13. An improved shallow water equation model for water animation

    NASA Astrophysics Data System (ADS)

    Ai, Mingjing; Du, Anding; Xu, Han; Niu, Jianwei

    2017-03-01

    In this paper, we proposed a new scheme for simulating water flows under shallow water assumption. The method is an extension of traditional shallow water equations. In contrast to traditional methods, we design a dynamic coordinate system for modeling in order to efficiently simulate water flows. Within this system, we derive our specialized shallow water equations directly from the Navier-Stockes equation. At the same time, we develop an implicit mechanism for solving the advection term and a vector projection operator for solving the external forces acting on water. We also present a two-way coupling method for simulating the interaction between water and rigid solid. The experimental results show that the proposed scheme can achieve a more realistic and accurate water model compared with the traditional methods, especially when the solid surfaces are too steep. Also we demonstrate the efficiency of our method in several scenes, all run at least 50 frames per second on average which allows real-time simulation.

  14. Three-dimensional shallow water system: A relaxation approach

    NASA Astrophysics Data System (ADS)

    Liu, Xin; Mohammadian, Abdolmajid; Infante Sedano, Julio Ángel; Kurganov, Alexander

    2017-03-01

    We study a three-dimensional shallow water system, which is obtained from the three-dimensional Navier-Stokes equations after Reynolds averaging and under the simplifying hydrostatic pressure assumption. Since the three-dimensional shallow water system is generically not hyperbolic, it cannot be numerically solved using hyperbolic shock capturing schemes. At the same time, existing simple finite-difference and finite-volume methods may fail in simulations of unsteady flows with sharp gradients, such as dam-break and flood flows. To overcome this limitation, we propose a novel numerical method, which is based on a relaxation approach utilized to "hyperbolize" the three-dimensional shallow water system. The extended relaxation system is hyperbolic and we develop a second-order semi-discrete central-upwind scheme for it. The proposed numerical method can preserve "lake at rest" steady states and positivity of water depth over irregular bottom topography. The accuracy, stability and robustness of the developed numerical method is verified on five numerical experiments.

  15. Four new species of Haplosclerida (Porifera, Demospongiae) from the Aleutian Islands, Alaska.

    PubMed

    Lehnert, Helmut; Stone, Robert P

    2013-01-01

    Four new species of Haplosclerida are described from the Aleutian Islands, Alaska: Callyspongia mucosa n.sp., Cladocroce infundibulum n. sp., Cladocroce attu n. sp. and Cladocroce kiska n. sp. The new species are described and compared to congeners of the region. This is the northernmost record of the genus Callyspongia and the first record of the subgenus Callyspongia from the North Pacific Ocean. To accommodate Cladocroce kiska in its genus the definition has to be broadened to allow sigmas.

  16. 77 FR 72297 - Fisheries of the Exclusive Economic Zone Off Alaska; Gulf of Alaska; Proposed 2013 and 2014...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-05

    ... biomass trends for the following species are relatively stable: shallow-water flatfish, deep-water... Pacific cod, shallow-water flatfish, arrowtooth flounder, flathead sole, other rockfish, and Atka mackerel... (GHL) for Pacific cod so that the ABCs are not exceeded. The flathead sole, shallow-water flatfish,...

  17. Experimental Verification of Range-Dependent Inversion: Shallow Water Experiment 2006

    DTIC Science & Technology

    2016-06-07

    Experimental Verification of Range-Dependent Inversion: Shallow Water Experiment 2006 Subramaniam D. Rajan Scientific Solutions, Inc., 99...dependent shallow water environment. OBJECTIVES Modal dispersion data are input to inversion schemes that estimate sediment properties in a range...suitable data during the Shallow Water 2006 experiment to verify the feasibility of estimating the range dependent sediment properties from modal dispersion

  18. Integrating archaeology and ancient DNA to address invasive species colonization in the Gulf of Alaska.

    PubMed

    West, Catherine; Hofman, Courtney A; Ebbert, Steve; Martin, John; Shirazi, Sabrina; Dunning, Samantha; Maldonado, Jesus E

    2016-11-17

    The intentional and unintentional movement of plants and animals by humans has transformed ecosystems and landscapes globally. Assessing when and how a species was introduced are central to managing these transformed landscapes, particularly in island environments. In the Gulf of Alaska, there is considerable interest in the history of mammal introductions and rehabilitating Gulf of Alaska island environments by eradicating those mammals classified as invasive species. The Arctic ground squirrel (Urocitellus parryii) is of concern because of its effect on vegetation and seabirds on Gulf of Alaska islands. This animal is assumed to have been introduced by historic settlers, however, ground squirrel remains in the prehistoric archaeological record of Chirikof Island, Alaska challenges this timeline, suggesting that they colonized the islands long ago. This study uses three lines of evidence to address this problem: 1) direct radiocarbon dating of archaeological squirrel remains; 2) evidence of prehistoric human use of squirrels; and 3) ancient DNA analysis of dated squirrel remains. The results suggest that squirrels have been on Chirikof longer than previously assumed and that the current population of squirrels is closely related to the ancient population. This challenges the assumption that ground squirrels were a recent, human-mediated introduction and supports the hypothesis that they may have colonized the island via a natural dispersal event or an ancient human translocation. This article is protected by copyright. All rights reserved.

  19. Community Structure of Macrobiota and Environmental Parameters in Shallow Water Hydrothermal Vents off Kueishan Island, Taiwan

    PubMed Central

    Chan, Benny Kwok Kan; Wang, Teng-Wei; Chen, Pin-Chen; Lin, Chia-Wei; Chan, Tin-Yam; Tsang, Ling Ming

    2016-01-01

    Hydrothermal vents represent a unique habitat in the marine ecosystem characterized with high water temperature and toxic acidic chemistry. Vents are distributed at depths ranging from a few meters to several thousand meters. The biological communities of shallow-water vents have, however, been insufficiently studied in most biogeographic areas. We attempted to characterize the macrofauna and macroflora community inhabiting the shallow-water vents off Kueishan Island, Taiwan, to identify the main abiotic factors shaping the community structure and the species distribution. We determined that positively buoyant vent fluid exhibits a more pronounced negative impact to species on the surface water than on the bottom layer. Species richness increased with horizontal distance from the vent, and continuing for a distance of 2000 m, indicating that the vent fluid may exert a negative impact over several kilometers. The community structure off Kueishan Island displayed numerous transitions along the horizontal gradient, which were broadly congruent with changes in environmental conditions. Combination of variation in Ca2+, Cl-, temperature, pH and depth were revealed to show the strongest correlation with the change in benthic community structure, suggesting multiple factors of vent fluid were influencing the associated fauna. Only the vent crabs of Kueishan Island may have an obligated relationship with vents and inhabit the vent mouths because other fauna found nearby are opportunistic taxa that are more tolerant to acidic and toxic environments. PMID:26849440

  20. Community Structure of Macrobiota and Environmental Parameters in Shallow Water Hydrothermal Vents off Kueishan Island, Taiwan.

    PubMed

    Chan, Benny Kwok Kan; Wang, Teng-Wei; Chen, Pin-Chen; Lin, Chia-Wei; Chan, Tin-Yam; Tsang, Ling Ming

    2016-01-01

    Hydrothermal vents represent a unique habitat in the marine ecosystem characterized with high water temperature and toxic acidic chemistry. Vents are distributed at depths ranging from a few meters to several thousand meters. The biological communities of shallow-water vents have, however, been insufficiently studied in most biogeographic areas. We attempted to characterize the macrofauna and macroflora community inhabiting the shallow-water vents off Kueishan Island, Taiwan, to identify the main abiotic factors shaping the community structure and the species distribution. We determined that positively buoyant vent fluid exhibits a more pronounced negative impact to species on the surface water than on the bottom layer. Species richness increased with horizontal distance from the vent, and continuing for a distance of 2000 m, indicating that the vent fluid may exert a negative impact over several kilometers. The community structure off Kueishan Island displayed numerous transitions along the horizontal gradient, which were broadly congruent with changes in environmental conditions. Combination of variation in Ca2+, Cl-, temperature, pH and depth were revealed to show the strongest correlation with the change in benthic community structure, suggesting multiple factors of vent fluid were influencing the associated fauna. Only the vent crabs of Kueishan Island may have an obligated relationship with vents and inhabit the vent mouths because other fauna found nearby are opportunistic taxa that are more tolerant to acidic and toxic environments.

  1. Plant pigment types, distributions, and influences on shallow water submerged aquatic vegetation mapping

    NASA Astrophysics Data System (ADS)

    Hall, Carlton R.; Bostater, Charles R., Jr.; Virnstein, Robert

    2004-11-01

    Development of robust protocols for use in mapping shallow water habitats using hyperspectral imagery requires knowledge of absorbing and scattering features present in the environment. These include, but are not limited to, water quality parameters, phytoplankton concentrations and species, submerged aquatic vegetation (SAV) species and densities, epiphytic growth on SAV, benthic microalgae and substrate reflectance characteristics. In the Indian River Lagoon, Fl. USA we conceptualize the system as having three possible basic layers, water column and SAV bed above the bottom. Each layer is occupied by plants with their associated light absorbing pigments that occur in varying proportions and concentrations. Phytoplankton communities are composed primarily of diatoms, dinoflagellates, and picoplanktonic cyanobacteria. SAV beds, including flowering plants and green, red, and brown macro-algae exist along density gradients ranging in coverage from 0-100%. SAV beds may be monotypic, or more typically, mixtures of the several species that may or may not be covered in epiphytes. Shallow water benthic substrates are colonized by periphyton communities that include diatoms, dinoflagellates, chlorophytes and cyanobacteria. Inflection spectra created form ASIA hyperspectral data display a combination of features related to water and select plant pigment absorption peaks.

  2. Acoustic Propagation Modeling in Shallow Water Using Ray Theory.

    NASA Astrophysics Data System (ADS)

    Westwood, Evan Kruse

    A ray method is developed for modeling acoustic propagation in low-frequency, shallow water ocean environments. The theoretical foundation is laid by studying the reflected and transmitted fields due to a point source in the presence of a plane, penetrable interface. Each field is expressed as a plane wave integral. The approach for solving the integral is based on the classical method of steepest descent, but the plane wave reflection and transmission coefficients are allowed to influence the location of the saddle points and their steepest descent paths. As a consequence, saddle points are, in general, complex, and complicated processes such as the reflected lateral wave field and the transmitted evanescent field are incorporated in the saddle point formulation. The saddle point criterion may be expressed in terms of eigenrays and their characteristics, providing physical insight into the paths and mechanisms of propagation. The method developed for solving the single interface problem is then applied to two simple models for shallow water ocean environments: the flat, isovelocity waveguide (the Pekeris model) and the sloping-bottom, isovelocity waveguide (the penetrable wedge). For the flat waveguide, near perfect agreement is found between the ray model and a model whose algorithm solves the wave equation numerically (the SAFARI fast field model). The ray method proves to be accurate even when the water depth is only half of the acoustic wavelength. For the sloping-bottom waveguide, ray model solutions to benchmark problems proposed by the Acoustical Society of America are compared to solutions from a model based on two-way coupled mode theory. For cases of upslope propagation in shallow-water penetrable wedges, agreement between the two independent models is excellent, both in the water and in the bottom. The ray method for the three-dimensional wedge problem is discussed, and the method is also extended to model directional sources by placing a point source

  3. Characteristics and Propagation of Airgun Pulses in Shallow Water with Implications for Effects on Small Marine Mammals

    PubMed Central

    Hermannsen, Line; Tougaard, Jakob; Beedholm, Kristian; Nabe-Nielsen, Jacob; Madsen, Peter Teglberg

    2015-01-01

    Airguns used in seismic surveys are among the most prevalent and powerful anthropogenic noise sources in marine habitats. They are designed to produce most energy below 100 Hz, but the pulses have also been reported to contain medium-to-high frequency components with the potential to affect small marine mammals, which have their best hearing sensitivity at higher frequencies. In shallow water environments, inhabited by many of such species, the impact of airgun noise may be particularly challenging to assess due to complex propagation conditions. To alleviate the current lack of knowledge on the characteristics and propagation of airgun pulses in shallow water with implications for effects on small marine mammals, we recorded pulses from a single airgun with three operating volumes (10 in3, 25 in3 and 40 in3) at six ranges (6, 120, 200, 400, 800 and 1300 m) in a uniform shallow water habitat using two calibrated Reson 4014 hydrophones and four DSG-Ocean acoustic data recorders. We show that airgun pulses in this shallow habitat propagated out to 1300 meters in a way that can be approximated by a 18log(r) geometric transmission loss model, but with a high pass filter effect from the shallow water depth. Source levels were back-calculated to 192 dB re µPa2s (sound exposure level) and 200 dB re 1 µPa dB Leq-fast (rms over 125 ms duration), and the pulses contained substantial energy up to 10 kHz, even at the furthest recording station at 1300 meters. We conclude that the risk of causing hearing damage when using single airguns in shallow waters is small for both pinnipeds and porpoises. However, there is substantial potential for significant behavioral responses out to several km from the airgun, well beyond the commonly used shut-down zone of 500 meters. PMID:26214849

  4. Community structure of age-0 fishes in paired mainstem and created shallow-water habitats in the Lower Missouri River

    USGS Publications Warehouse

    Starks, T. A.; Long, James M.; Dzialowski, Andrew R.

    2016-01-01

    Anthropogenic alterations to aquatic ecosystems have greatly reduced and homogenized riverine habitat, especially those used by larval and juvenile fishes. Creation of shallow-water habitats is used as a restoration technique in response to altered conditions in several studies globally, but only recently in the USA. In the summer of 2012, the U.S. Army Corps of Engineers sampled larval and juvenile fishes at six paired sites (mainstem and constructed chute shallow-water habitats) along a section of the Missouri River between Rulo, NE and St. Louis, MO, USA. From those samples, we enumerated and identified a total of 7622 fishes representing 12 families. Community responses of fishes to created shallow-water habitats were assessed by comparisons of species richness and diversity measures between paired sites and among sampling events. Shannon entropy measures were transformed, and gamma diversity (total diversity) was partitioned into two components, alpha (within community) and beta (between community) diversity using a multiplicative decomposition method. Mantel test results suggest site location, time of sampling event and habitat type were drivers of larval and juvenile community structure. Paired t-test results indicated little to no differences in beta diversity between habitat types; however, chute habitats had significantly higher alpha and gamma diversity as well as increased abundances of Asian carp larvae when compared with mainstem shallow-water habitat. Our results not only show the importance of created shallow-water habitat in promoting stream fish diversity but also highlight the role space and time may play in future restoration and management efforts. 

  5. 75 FR 38939 - Fisheries of the Economic Exclusive Zone Off Alaska; Deep-Water Species Fishery by Catcher...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-07

    ... Exclusive Zone Off Alaska; Deep-Water Species Fishery by Catcher/Processor Rockfish Cooperatives in the Gulf... for species that comprise the deep-water species fishery by catcher/processor rockfish cooperatives... limit specified for the deep-water species fishery by catcher/processor rockfish cooperatives subject...

  6. Shallow-water wave lensing in coral reefs: a physical and biological case study.

    PubMed

    Veal, Cameron James; Carmi, Maya; Dishon, Gal; Sharon, Yoni; Michael, Kelvin; Tchernov, Dan; Hoegh-Guldberg, Ove; Fine, Maoz

    2010-12-15

    Wave lensing produces the highest level of transient solar irradiances found in nature, ranging in intensity over several orders of magnitude in just a few tens of milliseconds. Shallow coral reefs can be exposed to wave lensing during light-wind, clear-sky conditions, which have been implicated as a secondary cause of mass coral bleaching through light stress. Management strategies to protect small areas of high-value reef from wave-lensed light stress were tested using seawater irrigation sprinklers to negate wave lensing by breaking up the water surface. A series of field and tank experiments investigated the physical and photophysiological response of the shallow-water species Stylophora pistillata and Favites abdita to wave lensing and sprinkler conditions. Results show that the sprinkler treatment only slightly reduces the total downwelling photosynthetically active and ultraviolet irradiance (∼5.0%), whereas it dramatically reduces, by 460%, the irradiance variability caused by wave lensing. Despite this large reduction in variability and modest reduction in downwelling irradiance, there was no detectable difference in photophysiological response of the corals between control and sprinkler treatments under two thermal regimes of ambient (27°C) and heated treatment (31°C). This study suggests that shallow-water coral species are not negatively affected by the strong flashes that occur under wave-lensing conditions.

  7. Modulational Instability and Rogue Waves in Shallow Water Models

    NASA Astrophysics Data System (ADS)

    Grimshaw, R.; Chow, K. W.; Chan, H. N.

    It is now well known that the focussing nonlinear Schrödinger equation allows plane waves to be modulationally unstable, and at the same time supports breather solutions which are often invoked as models for rogue waves. This suggests a direct connection between modulation instability and the existence of rogue waves. In this chapter we review this connection for a suite of long wave models, such as the Korteweg-de Vries equation, the extended Korteweg-de Vries (Gardner) equation, often used to describe surface and internal waves in shallow water, a Boussinesq equation and, also a coupled set of Korteweg-de Vries equations.

  8. New Analytical Solution for Nonlinear Shallow Water-Wave Equations

    NASA Astrophysics Data System (ADS)

    Aydin, Baran; Kânoğlu, Utku

    2017-03-01

    We solve the nonlinear shallow water-wave equations over a linearly sloping beach as an initial-boundary value problem under general initial conditions, i.e., an initial wave profile with and without initial velocity. The methodology presented here is extremely simple and allows a solution in terms of eigenfunction expansion, avoiding integral transform techniques, which sometimes result in singular integrals. We estimate parameters, such as the temporal variations of the shoreline position and the depth-averaged velocity, compare with existing solutions, and observe perfect agreement with substantially less computational effort.

  9. Jupiter's Great Red Spot as a shallow water system

    NASA Technical Reports Server (NTRS)

    Dowling, Timothy E.; Ingersoll, Andrew P.

    1989-01-01

    Voyager cloud-top velocity data for Jupiter's Great Red Spot (GRS) is used to derive the bottom topography up to a constant that depends on the unknown radius of deformation. The bottom topography is inferred from the Bernoulli streamfunction, kinetic energy per unit mass, and absolute vorticity values derived from the velocity data. The results are used to calculate potential vorticity versus latitude far from the vortex. It is found that the deep atmosphere is in differential motion and that the far-field potential vorticity gradient changes sign at several latitudes. Numerical experiments are conducted to study the time-dependent behavior of the shallow water analog of Jupiter's analog.

  10. Cartesian Methods for the Shallow Water Equations on a Sphere

    SciTech Connect

    Drake, J.B.

    2000-02-14

    The shallow water equations in a spherical geometry are solved using a 3-dimensional Cartesian method. Spatial discretization of the 2-dimensional, horizontal differential operators is based on the Cartesian form of the spherical harmonics and an icosahedral (spherical) grid. Computational velocities are expressed in Cartesian coordinates so that a problem with a singularity at the pole is avoided. Solution of auxiliary elliptic equations is also not necessary. A comparison is made between the standard form of the Cartesian equations and a rotational form using a standard set of test problems. Error measures and conservation properties of the method are reported for the test problems.

  11. Edge-based finite element method for shallow water equations

    NASA Astrophysics Data System (ADS)

    Ribeiro, F. L. B.; Galeão, A. C.; Landau, L.

    2001-07-01

    This paper describes an edge-based implementation of the generalized residual minimum (GMRES) solver for the fully coupled solution of non-linear systems arising from finite element discretization of shallow water equations (SWEs). The gain in terms of memory, floating point operations and indirect addressing is quantified for semi-discrete and space-time analyses. Stabilized formulations, including Petrov-Galerkin models and discontinuity-capturing operators, are also discussed for both types of discretization. Results illustrating the quality of the stabilized solutions and the advantages of using the edge-based approach are presented at the end of the paper. Copyright

  12. Traveling surface waves of moderate amplitude in shallow water

    PubMed Central

    Gasull, Armengol; Geyer, Anna

    2014-01-01

    We study traveling wave solutions of an equation for surface waves of moderate amplitude arising as a shallow water approximation of the Euler equations for inviscid, incompressible and homogeneous fluids. We obtain solitary waves of elevation and depression, including a family of solitary waves with compact support, where the amplitude may increase or decrease with respect to the wave speed. Our approach is based on techniques from dynamical systems and relies on a reformulation of the evolution equation as an autonomous Hamiltonian system which facilitates an explicit expression for bounded orbits in the phase plane to establish existence of the corresponding periodic and solitary traveling wave solutions. PMID:24895474

  13. Adaptivity in space and time for shallow water equations

    NASA Astrophysics Data System (ADS)

    Morandi Cecchi, M.; Marcuzzi, F.

    1999-09-01

    In this paper, adaptive algorithms for time and space discretizations are added to an existing solution method previously applied to the Venice Lagoon Tidal Circulation problem. An analysis of the interactions between space and time discretizations adaptation algorithms is presented. In particular, it turns out that both error estimations in space and time must be present for maintaining the adaptation efficiency. Several advantages, for adaptivity and for time decoupling of the equations, offered by the operator-splitting adopted for shallow water equations solution are presented. Copyright

  14. A temperature-tolerant interstitial worm with associated epibiotic bacteria from the shallow water fumaroles of Deception Island, Antarctica

    NASA Astrophysics Data System (ADS)

    Bright, M.; Arndt, C.; Keckeis, H.; Felbeck, H.

    2003-06-01

    A prominent not previously identified species of Monocelidae (Platyhelminthes, Proseriata) was found in the vicinity of fumarole activity at Fumarole Bay. The distribution of this animal and the metazoan meiobenthos in the vicinity of this area suggests that this species constitutes the most abundant species and the bulk of the biomass at these shallow water fumaroles. In contrast to the other metazoan meiofauna, the distribution of this species is positively correlated with the water temperature and gas emissions, indicating a preference for the areas around fumaroles. The range of temperature tolerated by this animal was determined in in vivo experiments to be at least 30-40°C. The outer surface the animals is colonized by apparently symbiotic bacteria, which are usually rod-like and approximately 0.68 μm wide and 2.07 μm long. The results of this study revealed a remarkable difference between shallow-water and deep-sea hydrothermal vent meiobenthic communities. Generalists capable of tolerating extreme abiotic conditions appear to dominate shallow-water vents, whereas endemism seems to be the rule in the deep-sea vents.

  15. Assessing Tsunami Vulnerabilities of Geographies with Shallow Water Equations

    NASA Technical Reports Server (NTRS)

    Aras, Rifat; Shen, Yuzhong

    2012-01-01

    Tsunami preparedness is crucial for saving human lives in case of disasters that involve massive water movement. In this work, we develop a framework for visual assessment of tsunami preparedness of geographies. Shallow water equations (also called Saint Venant equations) are a set of hyperbolic partial differential equations that are derived by depth-integrating the Navier-Stokes equations and provide a great abstraction of water masses that have lower depths compared to their free surface area. Our specific contribution in this study is to use Microsoft's XNA Game Studio to import underwater and shore line geographies, create different tsunami scenarios, and visualize the propagation of the waves and their impact on the shore line geography. Most importantly, we utilized the computational power of graphical processing units (GPUs) as HLSL based shader files and delegated all of the heavy computations to the GPU. Finally, we also conducted a validation study, in which we have tested our model against a controlled shallow water experiment. We believe that such a framework with an easy to use interface that is based on readily available software libraries, which are widely available and easily distributable, would encourage not only researchers, but also educators to showcase ideas.

  16. High-rate multiuser communications in shallow water.

    PubMed

    Song, H C; Kim, J S; Hodgkiss, W S; Kuperman, W A; Stevenson, M

    2010-11-01

    Passive multiuser communications in shallow water previously was demonstrated in the 3-4 kHz band using a time reversal approach. This paper extends those experimental results in three respects. First, a larger bandwidth at higher frequency (11-19 kHz) is employed allowing for the use of various symbol rates (or bandwidths). Second, two different shaping pulses are examined: a raised cosine filter and LFM (linear frequency modulation) chirp. Third, the adaptive time reversal approach with spatial nulling is applied to suppress the crosstalk among users. It is shown that the use of a larger bandwidth is beneficial along with the time reversal receiver which can handle significant intersymbol interference with minimal computational complexity. In addition, adding each user degrades the performance by about 4 dB for the benefit of linear increase in data rate. It is demonstrated that an aggregate data rate of 60 kbits/s can be achieved with a 7.5 kHz bandwidth (a spectral efficiency of 8 bits/s Hz) by three users distributed over 4.2-m depth at a 2.2 km range in shallow water using 16-QAM (quadrature amplitude modulation).

  17. Shallow water imaging sonar system for environmental surveying. Final report

    SciTech Connect

    1998-05-01

    The scope of this research is to develop a shallow water sonar system designed to detect and map the location of objects such as hazardous wastes or discarded ordnance in coastal waters. The system will use high frequency wide-bandwidth imaging sonar, mounted on a moving platform towed behind a boat, to detect and identify objects on the sea bottom. Resolved images can be obtained even if the targets are buried in an overlayer of silt. The specific technical objective of this research was to develop and test a prototype system that is capable of (1) scan at high speeds (up to 10m/s), even in shallow water (depth to ten meters), without motion blurring or loss of resolution; (2) produce images of the bottom structure that are detailed enough for unambiguous detection of objects as small as 15cm, even if they are buried up to 30cm deep in silt or sand. The critical technology involved uses an linear FM (LFM) or similar complex waveform, which has a high bandwidth for good range resolution, with a long pulse length for similar Dopper resolution. The lone duration signal deposits more energy on target than a narrower pulse, which increases the signal-to-noise ratio and signal-to-clutter ratio. This in turn allows the use of cheap, lightweight, low power, piezoelectric transducers at the 30--500 kHz range.

  18. For seismic profiling in very shallow water, a novel receiver

    SciTech Connect

    Simpkin, P.G. ); Davis, A. )

    1993-09-01

    There is an increasing interest in the geology of the nearshore and coastal zone. Working in the coastal zone, groups involved in civil engineering projects, pipeline and cable installations, marine transportation and navigation, recreational and harbor developments, and coastal defenses and environmental bodies demand better and more informative data. Although detailed site-specific information from borehole drilling, sample testing, or in-situ geotechnical measurements may be required, it is common practice and invariably cost effective to undertake a reconnaissance geophysical survey program first -- identifying borehole locations, providing geological and bathymetric information, and providing information on sediment distribution and the dynamics of the depositional regime. Used extensively by the offshore industry for many years, seismic reflection profiling is the preferred geophysical technique for high resolution structural-stratigraphic investigation of the seafloor. However, seismic data collection in very shallow water has posed many problems technically, operationally, and logistically. Recently, there have been significant developments in marine geophysical survey procedures -- a novel technique for seismic profiling in shallow water that can extend to depths of 2 meters or less has been developed.

  19. Global dynamical behaviors in a physical shallow water system

    NASA Astrophysics Data System (ADS)

    Tchakoutio Nguetcho, Aurélien Serge; Li, Jibin; Bilbault, Jean-Marie

    2016-07-01

    The theory of bifurcations of dynamical systems is used to investigate the behavior of travelling wave solutions in an entire family of shallow water wave equations. This family is obtained by a perturbative asymptotic expansion for unidirectional shallow water waves. According to the parameters of the system, this family can lead to different sets of known equations such as Camassa-Holm, Korteweg-de Vries, Degasperis and Procesi and several other dispersive equations of the third order. Looking for possible travelling wave solutions, we show that different phase orbits in some regions of parametric planes are similar to those obtained with the model of the pressure waves studied by Li and Chen. Many other exact explicit travelling waves solutions are derived as well, some of them being in perfect agreement with solutions obtained in previous works by researchers using different methods. When parameters are varied, the conditions under which the above solutions appear are also shown. The dynamics of singular nonlinear travelling system is completely determined for each of the above mentioned equations. Moreover, we define sufficient conditions leading to the existence of propagating wave solutions and demonstrate how and why travelling waves lose their smoothness and develop into solutions with compact support or breaking waves.

  20. Momentum balance in the shallow water equations on bottom discontinuities

    NASA Astrophysics Data System (ADS)

    Valiani, A.; Caleffi, V.

    2017-02-01

    This work investigates the topical problem of balancing the shallow water equations over bottom steps of different heights. The current approaches in the literature are essentially based on mathematical analysis of the hyperbolic system of balance equations and take into account the relevant progresses in treating the non-conservative form of the governing system in the framework of path-conservative schemes. An important problem under debate is the correct position of the momentum balance closure when the bottom elevation is discontinuous. Cases of technical interest are systematically analysed, consisting of backward-facing steps and forward-facing steps, tackled supercritical and subcritical flows; critical (sonic) conditions are also analysed and discussed. The fundamental concept governing the problem and supported by the present computations is that the energy-conserving approach is the only approach that is consistent with the classical shallow water equations formulated with geometrical source terms and that the momentum balance is properly closed if a proper choice of a conventional depth on the bottom step is performed. The depth on the step is shown to be included between the depths just upstream and just downstream of the step. It is also shown that current choices (as given in the literature) of the depth on (or in front of) the step can lead to unphysical configurations, similar to some energy-increasing solutions.

  1. Description of Caurinus tlagu, new species, from Prince of Wales Island, Alaska (Mecoptera, Boreidae, Caurininae)

    PubMed Central

    Sikes, Derek S.; Stockbridge, Jill

    2013-01-01

    Abstract A new species of the cryptic, minute, wingless, and enigmatic taxon Caurinus, and the second for the subfamily Caurininae,is described from Prince of Wales Island in the Alexander Archipelago, Alaska. It is distinguished from its only congener, Caurinus dectes Russell, 1979b, which occurs 1,059 km southeast in Oregon and Washington, based on external morphology and sequences of the mitochondrial gene cytochrome oxidase II. These two species are probably evolutionary relicts – the only known members of a clade dating to the Late Jurassic or older. PMID:23878513

  2. The Toarcian Oceanic Anoxic Event: a shallow-water perspective

    NASA Astrophysics Data System (ADS)

    Bodin, Stephane; Krencker, Francois-Nicolas; Kabiri, Lahcen; Immenhauser, Adrian

    2015-04-01

    The Toarcian ocean anoxic event (T-OAE, ca. 183 Ma) corresponds to a major perturbation of the carbon cycle as reflected by a marked decrease (2 to 7 per mil) in carbon-isotope ratios of various carbonate and organic matter phases. Severe environmental perturbations and biotic turnovers are accompanying the unfolding of the T-OAE, which is thought to be initiated by the activity of the Karoo-Ferrar large igneous province. Most of the studies dedicated to the T-OAE were however undertaken in mud-rich, deep-water setting, leaving vast uncertainties about its shallow-water expression and accompanying sea-level fluctuations. Here we present an extensive sedimentological dataset of the shallow-water record of the T-OAE within the Central High Atlas Basin of Morocco. The combination of ammonite and brachiopod biostratigraphy, together with carbon-isotope chemostratigraphy (on both carbonate and organic matter) allows a precise location of the T-OAE in the studied shallow-water sections. Thanks to well-exposed and thick successions, relative sea-level variations were reconstructed on a high-resolution scale, highlighting several important facts. Firstly, the T-OAE interval is preceded by a 50 meters-deep incised valley, observed within the uppermost Polymorphum ammonite zone. Similar observations have been reported from Euro-boreal basins and, together with published evidences of coeval occurrence of relatively cool seawater temperature and low atmospheric pCO2, we postulate that this forced regression is driven by glacio-eustasy. This points at the occurrence of a "cold snap" event just prior to the onset of the T-OAE. Secondly, the inception of the T-OAE is marked by the demise of the Lithiotid-dominated neritic carbonate factory, replaced by siliciclastic-dominated sedimentation during the T-OAE negative carbon isotope shift. Thirdly, an important progradation of oo-biodetritic shoal occurs during the negative carbon isotope plateau, underlying that the renewal of

  3. Soluble, light-absorbing species in snow at Barrow, Alaska

    NASA Astrophysics Data System (ADS)

    Beine, Harry; Anastasio, Cort; Esposito, Giulio; Patten, Kelley; Wilkening, Elizabeth; Domine, Florent; Voisin, Didier; Barret, Manuel; Houdier, Stephan; Hall, Sam

    2011-07-01

    As part of the international multidisciplinary Ocean - Atmosphere - Sea Ice - Snowpack (OASIS) program we analyzed more than 500 terrestrial (melted) snow samples near Barrow, AK between February and April 2009 for light absorption, as well as H2O2 and inorganic anion concentrations. For light absorption in the photochemically active region (300-450 nm) of surface snows, H2O2 and NO3- make minor contributions (combined < 9% typically), while HUmic LIke Substances (HULIS) and unknown chromophores each account for approximately half of the total absorption. We have identified four main sources for our residual chromophores (i.e., species other than H2O2 or NO3-): (1) vegetation and organic debris impact mostly the lowest 20 cm of the snowpack, (2) marine inputs, which are identified by high Cl- and SO42- contents, (3) deposition of diamond dust to surface snow, and (4) gas-phase exchange between the atmosphere and surface snow layers. The snow surfaces, and accompanying chromophore concentrations, are strongly modulated by winds and snowfall at Barrow. However, even with these physical controls on light absorption, we see an overall decline of light absorption in near-surface snow during the 7 weeks of our campaign, likely due to photo-bleaching of chromophores. While HULIS and unknown chromophores dominate light absorption by soluble species in Barrow snow, we know little about the photochemistry of these species, and thus we as a community are probably overlooking many snowpack photochemical reactions.

  4. Molecular phylogeny of the benthic shallow-water octopuses (Cephalopoda: Octopodinae).

    PubMed

    Guzik, Michelle T; Norman, Mark D; Crozier, Ross H

    2005-10-01

    Octopus has been regarded as a "catch all" genus, yet its monophyly is questionable and has been untested. We inferred a broad-scale phylogeny of the benthic shallow-water octopuses (subfamily Octopodinae) using amino acid sequences of two mitochondrial DNA genes: Cytochrome oxidase subunit III and Cytochrome b apoenzyme, and the nuclear DNA gene Elongation Factor-1alpha. Sequence data were obtained from 26 Octopus species and from four related genera. Maximum likelihood and Bayesian approaches were implemented to estimate the phylogeny, and non-parametric bootstrapping was used to verify confidence for Bayesian topologies. Phylogenetic relationships between closely related species were generally well resolved, and groups delineated, but the genes did not resolve deep divergences well. The phylogenies indicated strongly that Octopus is not monophyletic, but several monophyletic groups were identified within the genus. It is therefore clear that octopodid systematics requires major revision.

  5. Thermal adaptations in deep-sea hydrothermal vent and shallow-water shrimp

    NASA Astrophysics Data System (ADS)

    Smith, Felix; Brown, Alastair; Mestre, Nélia C.; Reed, Adam J.; Thatje, Sven

    2013-08-01

    The hydrothermal vent shrimp Mirocaris fortunata is commonly exposed to acute thermal gradients and rapid fluctuations in water temperature. The shallow-water shrimp Palaemonetes varians experiences less acute but similar magnitude fluctuations in its thermal regime. Acute respiratory response to temperature shock, and temperature preference was assessed for both species. Oxygen consumption rates were assessed across the natural temperature range reported for M. fortunata. Rates increased with temperature for both species. P. varians had a significantly higher rate of oxygen consumption than M. fortunata at all temperatures except 4 °C. The rate of increase in oxygen consumption with increasing temperature was also significantly greater for P. varians. M. fortunata selected a significantly higher temperature than P. varians. Mirocaris fortunata maintains its metabolism at a more stable rate, which is likely an adaptation to acute changes in temperatures occurring at hydrothermal vents.

  6. Expansion shock waves in regularized shallow-water theory

    NASA Astrophysics Data System (ADS)

    El, Gennady A.; Hoefer, Mark A.; Shearer, Michael

    2016-05-01

    We identify a new type of shock wave by constructing a stationary expansion shock solution of a class of regularized shallow-water equations that include the Benjamin-Bona-Mahony and Boussinesq equations. An expansion shock exhibits divergent characteristics, thereby contravening the classical Lax entropy condition. The persistence of the expansion shock in initial value problems is analysed and justified using matched asymptotic expansions and numerical simulations. The expansion shock's existence is traced to the presence of a non-local dispersive term in the governing equation. We establish the algebraic decay of the shock as it is gradually eroded by a simple wave on either side. More generally, we observe a robustness of the expansion shock in the presence of weak dissipation and in simulations of asymmetric initial conditions where a train of solitary waves is shed from one side of the shock.

  7. Ecological succession of a Jurassic shallow-water ichthyosaur fall.

    PubMed

    Danise, Silvia; Twitchett, Richard J; Matts, Katie

    2014-09-10

    After the discovery of whale fall communities in modern oceans, it has been hypothesized that during the Mesozoic the carcasses of marine reptiles created similar habitats supporting long-lived and specialized animal communities. Here, we report a fully documented ichthyosaur fall community, from a Late Jurassic shelf setting, and reconstruct the ecological succession of its micro- and macrofauna. The early 'mobile-scavenger' and 'enrichment-opportunist' stages were not succeeded by a 'sulphophilic stage' characterized by chemosynthetic molluscs, but instead the bones were colonized by microbial mats that attracted echinoids and other mat-grazing invertebrates. Abundant cemented suspension feeders indicate a well-developed 'reef stage' with prolonged exposure and colonization of the bones prior to final burial, unlike in modern whale falls where organisms such as the ubiquitous bone-eating worm Osedax rapidly destroy the skeleton. Shallow-water ichthyosaur falls thus fulfilled similar ecological roles to shallow whale falls, and did not support specialized chemosynthetic communities.

  8. Reverberation clutter induced by nonlinear internal waves in shallow water.

    PubMed

    Henyey, Frank S; Tang, Dajun

    2013-10-01

    Clutter is related to false alarms for active sonar. It is demonstrated that, in shallow water, target-like clutter in reverberation signals can be caused by nonlinear internal waves. A nonlinear internal wave is modeled using measured stratification on the New Jersey shelf. Reverberation in the presence of the internal wave is modeled numerically. Calculations show that acoustic energy propagating near a sound speed minimum is deflected as a high intensity, higher angle beam into the bottom, where it is backscattered along the reciprocal path. The interaction of sound with the internal wave is isolated in space, hence resulting in a target-like clutter, which is found to be greater than 10 dB above the mean reverberation level.

  9. Modeling of SAR signatures of shallow water ocean topography

    NASA Technical Reports Server (NTRS)

    Shuchman, R. A.; Kozma, A.; Kasischke, E. S.; Lyzenga, D. R.

    1984-01-01

    A hydrodynamic/electromagnetic model was developed to explain and quantify the relationship between the SEASAT synthetic aperture radar (SAR) observed signatures and the bottom topography of the ocean in the English Channel region of the North Sea. The model uses environmental data and radar system parameters as inputs and predicts SAR-observed backscatter changes over topographic changes in the ocean floor. The model results compare favorably with the actual SEASAT SAR observed backscatter values. The developed model is valid for only relatively shallow water areas (i.e., less than 50 meters in depth) and suggests that for bottom features to be visible on SAR imagery, a moderate to high velocity current and a moderate wind must be present.

  10. On shallow water rogue wave formation in strongly inhomogeneous channels

    NASA Astrophysics Data System (ADS)

    Didenkulova, Ira; Pelinovsky, Efim

    2016-05-01

    Rogue wave formation in shallow water is often governed by dispersive focusing and wave-bottom interaction. In this study we try to combine these mechanisms by considering dispersive nonreflecting wave propagation in shallow strongly inhomogeneous channels. Nonreflecting wave propagation provides extreme wave amplification and the transfer of wave energy over large distances, while dispersive effects allow formation of a short-lived wave of extreme height (rogue wave). We found several types of water channels, where this mechanism can be realized, including (i) channels with a monotonically decreasing cross-section (normal dispersion), (ii) an inland basin described by a half of elliptic paraboloid (abnormal dispersion) and (iii) an underwater hill described by a half of hyperbolic paraboloid (normal dispersion). Conditions for variations of local frequency in the wave train providing optimal focusing of the wave train are also found.

  11. Hyperspectral Remote Sensing for Shallow Waters. I. A Semianalytical Model

    NASA Astrophysics Data System (ADS)

    Lee, Zhongping; Carder, Kendall L.; Mobley, Curtis D.; Steward, Robert G.; Patch, Jennifer S.

    1998-09-01

    For analytical or semianalytical retrieval of shallow-water bathymetry and or optical properties of the water column from remote sensing, the contribution to the remotely sensed signal from the water column has to be separated from that of the bottom. The mathematical separation involves three diffuse attenuation coefficients: one for the downwelling irradiance ( K d ), one for the upwelling radiance of the water column ( K u C ), and one for the upwelling radiance from bottom reflection ( K u B ). Because of the differences in photon origination and path lengths, these three coefficients in general are not equal, although their equality has been assumed in many previous studies. By use of the Hydrolight radiative-transfer numerical model with a particle phase function typical of coastal waters, the remote-sensing reflectance above ( R rs ) and below ( r rs ) the surface is calculated for various combinations of optical properties, bottom albedos, bottom depths, and solar zenith angles. A semianalytical (SA) model for r rs of shallow waters is then developed, in which the diffuse attenuation coefficients are explicitly expressed as functions of in-water absorption ( a ) and backscattering ( b b ). For remote-sensing inversion, parameters connecting R rs and r rs are also derived. It is found that r rs values determined by the SA model agree well with the exact values computed by Hydrolight ( 3% error), even for Hydrolight r rs values calculated with different particle phase functions. The Hydrolight calculations included b b a values as high as 1.5 to simulate high-turbidity situations that are occasionally found in coastal regions.

  12. Tree Species Linked to Large Differences in Ecosystem Carbon Distribution in the Boreal Forest of Alaska

    NASA Astrophysics Data System (ADS)

    Melvin, A. M.; Mack, M. C.; Johnstone, J. F.; Schuur, E. A. G.; Genet, H.; McGuire, A. D.

    2014-12-01

    In the boreal forest of Alaska, increased fire severity associated with climate change is altering plant-soil-microbial feedbacks and ecosystem carbon (C) dynamics. The boreal landscape has historically been dominated by black spruce (Picea mariana), a tree species associated with slow C turnover and large soil organic matter (SOM) accumulation. Historically, low severity fires have led to black spruce regeneration post-fire, thereby maintaining slow C cycling rates and large SOM pools. In recent decades however, an increase in high severity fires has led to greater consumption of the soil organic layer (SOL) during fire and subsequent establishment of deciduous tree species in areas previously dominated by black spruce. This shift to a more deciduous dominated landscape has many implications for ecosystem structure and function, as well as feedbacks to global C cycling. To improve our understanding of how boreal tree species affect C cycling, we quantified above- and belowground C stocks and fluxes in adjacent, mid-successional stands of black spruce and Alaska paper birch (Betula neoalaskana) that established following a 1958 fire near Fairbanks, Alaska. Although total ecosystem C pools (aboveground live tree biomass + dead wood + SOL + top 10 cm of mineral soil) were similar for the two stand types, the distribution of C among pools was markedly different. In black spruce, 78% of measured C was found in soil pools, primarily in the SOL, where spruce contained twice the C stored in paper birch (4.8 ± 0.3 vs. 2.4 ± 0.1 kg C m-2). In contrast, aboveground biomass dominated ecosystem C pools in birch forest (6.0 ± 0.3 vs. 2.5 ± 0.2 kg C m-2 in birch and spruce, respectively). Our findings suggest that tree species exert a strong influence over plant-soil-microbial feedbacks and may have long-term effects on ecosystem C sequestration and storage that feedback to the climate system.

  13. New species of sponges (Porifera, Demospongiae) from the Aleutian Islands and Gulf of Alaska.

    PubMed

    Lehnert, Helmut; Stone, Robert P

    2015-10-27

    Ten new species of demosponges, assigned to the orders Poecilosclerida, Axinellida and Dictyoceratida, discovered in the Gulf of Alaska and along the Aleutian Island Archipelago are described and compared to relevant congeners. Poecilosclerida include Cornulum globosum n. sp., Megaciella lobata n. sp., M. triangulata n. sp., Artemisina clavata n. sp., A. flabellata n. sp., Coelosphaera (Histodermion) kigushimkada n. sp., Stelodoryx mucosa n. sp. and S. siphofuscus n. sp. Axinellida is represented by Raspailia (Hymeraphiopsis) fruticosa n. sp. and Dictyoceratida is represented by Dysidea kenkriegeri n. sp. The genus Cornulum is modified to allow for smooth tylotes. We report several noteworthy biogeographical observations. We describe only the third species within the subgenus Histodermion and the first from the Indo-Pacific Region. Additionally, the subgenus Hymerhaphiopsis was previously represented by only a single species from Antarctica. We also report the first record of a dictyoceratid species from Alaska. The new collections further highlight the richness of the sponge fauna from the region, particularly for the Poecilosclerida.

  14. An Expendable Source for Measuring Shallow Water Acoustic Propagation and Geo-Acoustic Bottom Properties

    DTIC Science & Technology

    2015-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. An Expendable Source for Measuring Shallow Water Acoustic ...Propagation and Geo- Acoustic Bottom Properties Harry A DeFerrari RSMAS – University of Miami 4600 Rickenbacker Causeway Miami FL. 33149...broadband source is being developed that transmits high gain m-sequence to clandestinly measure pulse response of shallow water acoustic propagation

  15. 78 FR 36150 - Fisheries of the Exclusive Economic Zone Off Alaska; Tanner Crab Area Closure in the Gulf of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-17

    ....regulations.gov or from the NMFS Alaska Region Web site at http://alaskafisheries.noaa.gov . FOR FURTHER... flatfish fisheries include directed fisheries for shallow-water flatfish, deep-water flatfish, arrowtooth... a retained aggregate amount of shallow-water flatfish, deep-water flatfish, rex sole,...

  16. New beach ridge type: severely limited fetch, very shallow water

    SciTech Connect

    Tanner, W.F.; Demirpolat, S.

    1988-09-01

    The southern end of Laguna Madre (Texas) north of the Rio Grande mouth is marked by very shallow water, wide tidal flats, lunettes, islands made of beach ridges, and lesser features. The number and variety of islands in the lagoon is remarkable. The lunettes (clay dunes) are made primarily of quartz sand and coarse silt. They are common 5-10 m high, irregular in shape, and steep sided. They were deposited from wind transport and did not migrate. Those that are islands in the lagoon predate present position of sea level. Islands made of beach ridges were built from the lagoon side. Photoanalysis, field work, and granulometry all show that this sand was not moved into these ridges by Gulf of Mexico waves. Trenches in 12 beach ridges showed horizontal bedding but neither low-angle nor steep cross-bedding (quite unlike swash-built beach ridges). The ridges were built by wind-tide lag effects, not from the swash. Therefore, these beach ridges are a new type, in addition to swash-built, eolian, and storm-surge ridges. Growth of the ridges appears to be completed.

  17. Sound scattering in shallow water in presence of internal solitons

    NASA Astrophysics Data System (ADS)

    Katsnelson, Boris G.; Pereselkov, Serguey A.; Petnikov, Valery G.

    2002-05-01

    Sound scattering by localized inhomogeneity (object) in a shallow-water waveguide is studied. Influence of internal solitons (IS) traveling in the sea, on the scattered field is considered. The problem is analyzed within the framework of theory of the sound scattering in the waveguide developed by the authors, where the scattering matrix is expressed through modal decomposition including the scattering amplitude of the object in free space. The peculiarity of the given work is the taking into account of additional modes conversion due to IS. The waveguide and IS are modeled on the basis of experimental data (sound-speed profile, bottom relief, IS parameters, etc.) collected in the Japan Sea. The inhomogeneity is selected in the form of soft spheroids with dimensions characteristic of gray whales (eschrichtius). Calculations of amplitude fluctuations of the low-frequency sound field at the receiving point are carried out for moving spheroid and different orientations of acoustic track with respect to direction of propagation of IS. It is shown that sound fluctuations have essentially different characteristics for longitudinal and transversal propagation of IS. [Work supported by RFBR, Grant No. 00-05-64752.

  18. Polar Vortices in Shallow Water Simulations of Gas Giants

    NASA Astrophysics Data System (ADS)

    O'Neill, Morgan E.; Emanuel, Kerry

    2014-11-01

    Jupiter, Saturn and Neptune each exhibit unique polar atmospheric behavior. Assuming these flows are due to shallow dynamics, we explore the parameter space potentially responsible for the difference between each planet's polar features. The best observations have come from the Cassini misson to Saturn. Among many discoveries, a massive, warm and cyclonic vortex has been observed on each pole. The South Polar Vortex (SPV), specifically, has the highest measured temperatures on Saturn, a double eyewall, deep eye and a rapid cyclonic jet with the second highest windspeeds observed on the planet. Numerous small, vortical, and potentially convective systems are embedded within the large-scale flow of the SPV. Given these observations, we explore one potential mechanism of polar vortex maintenance: up-scale, poleward vorticity flux due to vortical hot towers (VHTs). Large GCMs cannot yet resolve local deep convection in the weather layer. Using a reduced gravity shallow water model on a polar beta plane, we represent convective towers with mass-flux driven vortex pairs and allow them to move freely. We show that there exist multiple regimes of polar flow, and that small and/or quickly rotating planets with sufficient total energy favor a polar cyclone in our simulations.

  19. Syndepositional shallow-water precipitation of glauconitic minerals

    NASA Astrophysics Data System (ADS)

    Chafetz, H. S.; Reid, A.

    2000-10-01

    Numerous studies have demonstrated that glauconitic minerals predominantly form in water depths of mid-shelf to upper slope in modern oceans. These areas tend to have slow sedimentation rates, another commonly cited requisite for glauconitic mineral precipitation. Cambro-Ordovician strata from the southwestern US are rich in glauconitic minerals. Stratigraphic, sedimentological, and petrographic constraints indicate that the glauconitic minerals are autochthonous. In marked contrast to the modern environments of deposition, these Cambro-Ordovician strata formed under very shallow-water to tidal-flat conditions. The trough cross-stratified deposits of the most glauconitic mineral-rich accumulations (glaucarenites) indicate a high energy environment and probably a normal to high rate of sedimentation. The presence of fibroradiated rims of glauconitic minerals on glauconitic mineral pellets, echinoderm fragments, and quartz grains demonstrates that the Cambro-Ordovician glauconitic minerals precipitated on or in close proximity to the sea floor and prior to calcite precipitation. Consequently, glauconitic minerals must have formed under markedly different conditions in the lower Paleozoic than they do today. Thus, the occurrence of glauconitic minerals in the rock record cannot be used a priori as an environmental indicator of either mid-shelf and deeper water and/or a slow rate of sedimentation.

  20. A new Shallow Water Cabled OBS System off California

    NASA Astrophysics Data System (ADS)

    Rademacher, Horst; Pearcey, Chris; Mangano, Giorgio; Guralp, Cansun; Pearce, Nathan

    2014-05-01

    During the summer and fall of 2013 we installed a turnkey cabled network of four combination broadband velocity/acceleration ocean bottom sensors (OBS) on the sea floor near Point Buchon in the Northeastern Pacific Ocean off the coast of Central California. We implemented a novel network design by daisy-chaining the instruments to one single multistranded cable. The signals of each station are digitized in-situ and then transmitted via dedicated optical fiber links inside the cable to a shore station. From there they are fed in real time via a cell phone modem into several seismic networks in California. The goal of this dense network is to monitor the microseismicity of two offshore faults running parallel to the strike of the San Andreas Fault. However, because the network is installed in rather shallow water near the coast, the action of waves and swell at the sea surface affect the sensor registrations much stronger as compared to the typical deep water installation of OBS equipment. We will report about the challenges of installing and maintaining the network and present some initial results.

  1. On the parameters of absorbing layers for shallow water models

    NASA Astrophysics Data System (ADS)

    Modave, Axel; Deleersnijder, Éric; Delhez, Éric J. M.

    2010-02-01

    Absorbing/sponge layers used as boundary conditions for ocean/marine models are examined in the context of the shallow water equations with the aim to minimize the reflection of outgoing waves at the boundary of the computational domain. The optimization of the absorption coefficient is not an issue in continuous models, for the reflection coefficient of outgoing waves can then be made as small as we please by increasing the absorption coefficient. The optimization of the parameters of absorbing layers is therefore a purely discrete problem. A balance must be found between the efficient damping of outgoing waves and the limited spatial resolution with which the resulting spatial gradients must be described. Using a one-dimensional model as a test case, the performances of various spatial distributions of the absorption coefficient are compared. Two shifted hyperbolic distributions of the absorption coefficient are derived from theoretical considerations for a pure propagative and a pure advective problems. These distribution show good performances. Their free parameter has a well-defined interpretation and can therefore be determined on a physical basis. The properties of the two shifted hyperbolas are illustrated using the classical two-dimensional problems of the collapse of a Gaussian-shaped mound of water and of its advection by a mean current. The good behavior of the resulting boundary scheme remains when a full non-linear dynamics is taken into account.

  2. High Resolution Marine Magnetic Survey of Shallow Water Littoral Area

    PubMed Central

    Ginzburg, Boris; Cohen, Tsuriel Ram; Zafrir, Hovav; Alimi, Roger; Salomonski, Nizan; Sharvit, Jacob

    2007-01-01

    The purpose of this paper is to present a system developed for detection and accurate mapping of ferro-metallic objects buried below the seabed in shallow waters. The system comprises a precise magnetic gradiometer and navigation subsystem, both installed on a non-magnetic catamaran towed by a low-magnetic interfering boat. In addition we present the results of a marine survey of a near-shore area in the vicinity of Atlit, a town situated on the Mediterranean coast of Israel, about 15 km south of Haifa. The primary purpose of the survey was to search for a Harvard airplane that crashed into the sea in 1960. A magnetic map of the survey area (3.5 km2 on a 0.5 m grid) was created revealing the anomalies at sub-meter accuracy. For each investigated target location a corresponding ferro-metallic item was dug out, one of which turned to be very similar to a part of the crashed airplane. The accuracy of location was confirmed by matching the position of the actual dug artifacts with the magnetic map within a range of ± 1 m, in a water depth of 9 m.

  3. Modeling rapid mass movements using the shallow water equations

    NASA Astrophysics Data System (ADS)

    Hergarten, S.; Robl, J.

    2014-11-01

    We propose a new method to model rapid mass movements on complex topography using the shallow water equations in Cartesian coordinates. These equations are the widely used standard approximation for the flow of water in rivers and shallow lakes, but the main prerequisite for their application - an almost horizontal fluid table - is in general not satisfied for avalanches and debris flows in steep terrain. Therefore, we have developed appropriate correction terms for large topographic gradients. In this study we present the mathematical formulation of these correction terms and their implementation in the open source flow solver GERRIS. This novel approach is evaluated by simulating avalanches on synthetic and finally natural topographies and the widely used Voellmy flow resistance law. The results are tested against analytical solutions and the commercial avalanche model RAMMS. The overall results are in excellent agreement with the reference system RAMMS, and the deviations between the different models are far below the uncertainties in the determination of the relevant fluid parameters and involved avalanche volumes in reality. As this code is freely available and open source, it can be easily extended by additional fluid models or source areas, making this model suitable for simulating several types of rapid mass movements. It therefore provides a valuable tool assisting regional scale natural hazard studies.

  4. Conservation laws and LETKF with 2D Shallow Water Model

    NASA Astrophysics Data System (ADS)

    Zeng, Yuefei; Janjic, Tijana

    2016-04-01

    Numerous approaches have been proposed to maintain physical conservation laws in the numerical weather prediction models. However, to achieve a reliable prediction, adequate initial conditions are also necessary, which are produced by a data assimilation algorithm. If an ensemble Kalman filters (EnKF) is used for this purpose, it has been shown that it could yield unphysical analysis ensemble that for example violates principles of mass conservation and positivity preservation (e.g. Janjic et al 2014) . In this presentation, we discuss the selection of conservation criteria for the analysis step, and start with testing the conservation of mass, energy and enstrophy. The simple experiments deal with nonlinear shallow water equations and simulated observations that are assimilated with LETKF (Localized Ensemble Transform Kalman Filter, Hunt et al. 2007). The model is discretized in a specific way to conserve mass, angular momentum, energy and enstrophy. The effects of the data assimilation on the conserved quantities (of mass, energy and enstrophy) depend on observation covarage, localization radius, observed variable and observation operator. Having in mind that Arakawa (1966) and Arakawa and Lamb (1977) showed that the conservation of both kinetic energy and enstrophy by momentum advection schemes in the case of nondivergent flow prevents systematic and unrealistic energy cascade towards high wave numbers, a cause of excessive numerical noise and possible eventual nonlinear instability, we test the effects on prediction depending on the type of errors in the initial condition. The performance with respect to nonlinear energy cascade is assessed as well.

  5. Adaptive instant record signals applied to shallow water detection

    NASA Astrophysics Data System (ADS)

    Folégot, Thomas; de Rosny, Julien; Prada, Claire; Fink, Mathias

    2004-05-01

    Time reversal arrays are becoming common tools whether for detection, tomography or communication. These applications require the measurement of the response from the array to one or several receivers. The most natural way to record different impulse responses between several points is to generate pulses successively from each emitting point and directly record all the impulse responses on the recording points. However, this method is very time consuming and inefficient in terms of signal-to-noise ratio. Hence, in this work, we propose an original way of sending continuous signals simultaneously from all the sources, recording all the pressure fields on the receivers and processing them in order to extract the exact impulse responses by matched filter. To this end, the signals are adapted to the environment and, more specifically, to highly dispersive media. These adaptive instant records signals (AIRS) are used experimentally to detect targets using the time reversal operator decomposition method. The quality of the 15×15 transfer functions acquired simultaneously, and therefore, the detection capability is demonstrated in shallow water in the presence of bottom absorption and reverberation. Finally, the connection of AIRS with CDMA and FDMA that are two coding techniques used in telecommunication is shown.

  6. Progress in the development of shallow-water mapping systems

    USGS Publications Warehouse

    Bergeron, E.; Worley, C.R.; O'Brien, T.

    2007-01-01

    The USGS (US Geological Survey) Coastal and Marine Geology has deployed an advance autonomous shallow-draft robotic vehicle, Iris, for shallow-water mapping in Apalachicola Bay, Florida. The vehicle incorporates a side scan sonar system, seismic-reflection profiler, single-beam echosounder, and global positioning system (GPS) navigation. It is equipped with an onboard microprocessor-based motor controller, delivering signals for speed and steering to hull-mounted brushless direct-current thrusters. An onboard motion sensor in the Sea Robotics vehicle control system enclosure has been integrated in the vehicle to measure the vehicle heave, pitch, roll, and heading. Three water-tight enclosures are mounted along the vehicle axis for the Edgetech computer and electronics system including the Sea Robotics computer, a control and wireless communications system, and a Thales ZXW real-time kinematic (RTK) GPS receiver. The vehicle has resulted in producing high-quality seismic reflection and side scan sonar data, which will help in developing the baseline oyster habitat maps.

  7. Estimation of avian population sizes and species richness across a boreal landscape in Alaska

    USGS Publications Warehouse

    Handel, C.M.; Swanson, S.A.; Nigro, Debora A.; Matsuoka, S.M.

    2009-01-01

    We studied the distribution of birds breeding within five ecological landforms in Yukon-Charley Rivers National Preserve, a 10,194-km2 roadless conservation unit on the Alaska-Canada border in the boreal forest zone. Passerines dominated the avifauna numerically, comprising 97% of individuals surveyed but less than half of the 115 species recorded in the Preserve. We used distance-sampling and discrete-removal models to estimate detection probabilities, densities, and population sizes across the Preserve for 23 species of migrant passerines and five species of resident passerines. Yellow-rumped Warblers (Dendroica coronata) and Dark-eyed Juncos (Junco hyemalis) were the most abundant species, together accounting for 41% of the migrant passerine populations estimated. White-winged Crossbills (Loxia leucoptera), Boreal Chickadees (Poecile hudsonica), and Gray Jays (Perisoreus canadensis) were the most abundant residents. Species richness was greatest in the Floodplain/Terrace landform flanking the Yukon River but densities were highest in the Subalpine landform. Species composition was related to past glacial history and current physiography of the region and differed notably from other areas of the northwestern boreal forest. Point-transect surveys, augmented with auxiliary observations, were well suited to sampling the largely passerine avifauna across this rugged landscape and could be used across the boreal forest region to monitor changes in northern bird distribution and abundance. ?? 2009 The Wilson Ornithological Society.

  8. Acute combined pressure and temperature exposures on a shallow-water crustacean: novel insights into the stress response and high pressure neurological syndrome.

    PubMed

    Morris, J P; Thatje, S; Ravaux, J; Shillito, B; Fernando, D; Hauton, C

    2015-03-01

    Little is known about the ecological and physiological processes governing depth distribution limits in species. Temperature and hydrostatic pressure are considered to be two dominant factors. Research has shown that some marine ectotherms are shifting their bathymetric distributions in response to rapid anthropogenic ocean surface warming. Shallow-water species unable to undergo latitudinal range shifts may depend on bathymetric range shifts to seek refuge from warming surface waters. As a first step in constraining the molecular basis of pressure tolerance in shallow water crustaceans, we examined differential gene expression in response to acute pressure and temperature exposures in juveniles of the shallow-water shrimp Palaemonetes varians. Significant increases in the transcription of genes coding for an NMDA receptor-regulated protein, an ADP ribosylation factor, β-actin, two heat shock protein 70 kDa isoforms (HSP70), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were found in response to elevated pressure. NMDA receptors have been implicated in pathways of excitotoxic damage to neurons and the onset of high pressure neurological syndrome (HPNS) in mammals. These data indicate that the sub-lethal effects of acute barotrauma are associated with transcriptional disturbances within the nervous tissue of crustaceans, and cellular macromolecular damage. Such transcriptional changes lead to the onset of symptoms similar to that described as HPNS in mammals, and may act as a limit to shallow water organisms' prolonged survival at depth.

  9. Shallow water processes govern system-wide phytoplankton bloom dynamics: A field study

    USGS Publications Warehouse

    Thompson, J.K.; Koseff, Jeffrey R.; Monismith, Stephen G.; Lucas, L.V.

    2008-01-01

    Prior studies of the phytoplankton dynamics in South San Francisco Bay, California, USA have hypothesized that bivalve filter-feeders are responsible for the limited phytoplankton blooms in the system. This study was designed to examine the effects of benthic grazing and light attenuation on this shallow, turbid, and nutrient replete system. We found that grazing by shallow water bivalves was important in determining phytoplankton bloom occurrence throughout the system and that above a shallow water bivalve grazing threshold, phytoplankton biomass did not exceed bloom levels. Wind speed, used as a proxy for light attenuation in the shallow water, was similarly important in determining bloom development in the shallow water. Environmental conditions and benthic grazing in the deep water channel had a less discernible effect on system-wide phytoplankton blooms although persistent water column stratification did increase bloom magnitude. The shallow water bivalves, believed to be preyed upon by birds and fish that migrate through the system in fall and winter, disappear each year prior to the spring phytoplankton bloom. Because growth of the phytoplankton depends so strongly on shallow water processes, any change in the shallow-water benthic filter-feeders or their predators has great potential to change the phytoplankton bloom dynamics in this system. ?? 2007 Elsevier B.V. All rights reserved.

  10. Coordinating perception and action with an underwater robot in a shallow water environment

    NASA Astrophysics Data System (ADS)

    Bonasso, R. P.

    1992-04-01

    It is usually difficult to use underwater robots for mapping, reconnaissance, and mine-clearing tasks in shallow water (10 to 80 foot depth) ocean environments. The shallow water environment is characterized by strong, intermittent wave surge which requires robot behaviors that are capable of riding out the surge and then repositioning the platform and re- acquiring the objects being sensed. The shallow water area is also characterized by water that is murky, making optical sensors useless for long range search, and which produces multiple paths for sonar returns, giving errant range readings. Teleoperation from a remote surface platform is not effective due to the rapid changes in the environment. A more promising approach would place reactive intelligence on-board the robot. This paper describes such an approach which uses high frequency acoustic and vision sensing and a situated reasoning software architecture to provide task-achieving capability to an underwater robot in a shallow water environment. The approach is demonstrated in the context of a shallow water marking task wherein a robot must locate and navigate to a moored object in shallow water depths, attach a buoyant marker, and then return to a destination location. The approach seeks to integrate selective perception with robust transit and hovering behaviors to overcome the natural problems associated with shallow water environments.

  11. Relative Pigment Composition and Remote Sensing Reflectance of Caribbean Shallow-Water Corals.

    PubMed

    Torres-Pérez, Juan L; Guild, Liane S; Armstrong, Roy A; Corredor, Jorge; Zuluaga-Montero, Anabella; Polanco, Ramón

    2015-01-01

    Reef corals typically contain a number of pigments, mostly due to their symbiotic relationship with photosynthetic dinoflagellates. These pigments usually vary in presence and concentration and influence the spectral characteristics of corals. We studied the variations in pigment composition among seven Caribbean shallow-water Scleractinian corals by means of High Performance Liquid Chromatography (HPLC) analysis to further resolve the discrimination of corals. We found a total of 27 different pigments among the coral species, including some alteration products of the main pigments. Additionally, pigments typically found in endolithic algae were also identified. A Principal Components Analysis and a Hierarchical Cluster Analysis showed the separation of coral species based on pigment composition. All the corals were collected under the same physical environmental conditions. This suggests that pigment in the coral's symbionts might be more genetically-determined than influenced by prevailing physical conditions of the reef. We further investigated the use of remote sensing reflectance (Rrs) as a tool for estimating the total pigment concentration of reef corals. Depending on the coral species, the Rrs and the total symbiont pigment concentration per coral tissue area correlation showed 79.5-98.5% confidence levels demonstrating its use as a non-invasive robust technique to estimate pigment concentration in studies of coral reef biodiversity and health.

  12. Relative Pigment Composition and Remote Sensing Reflectance of Caribbean Shallow-Water Corals

    PubMed Central

    Torres-Pérez, Juan L.; Guild, Liane S.; Armstrong, Roy A.; Corredor, Jorge; Zuluaga-Montero, Anabella; Polanco, Ramón

    2015-01-01

    Reef corals typically contain a number of pigments, mostly due to their symbiotic relationship with photosynthetic dinoflagellates. These pigments usually vary in presence and concentration and influence the spectral characteristics of corals. We studied the variations in pigment composition among seven Caribbean shallow-water Scleractinian corals by means of High Performance Liquid Chromatography (HPLC) analysis to further resolve the discrimination of corals. We found a total of 27 different pigments among the coral species, including some alteration products of the main pigments. Additionally, pigments typically found in endolithic algae were also identified. A Principal Components Analysis and a Hierarchical Cluster Analysis showed the separation of coral species based on pigment composition. All the corals were collected under the same physical environmental conditions. This suggests that pigment in the coral’s symbionts might be more genetically-determined than influenced by prevailing physical conditions of the reef. We further investigated the use of remote sensing reflectance (Rrs) as a tool for estimating the total pigment concentration of reef corals. Depending on the coral species, the Rrs and the total symbiont pigment concentration per coral tissue area correlation showed 79.5–98.5% confidence levels demonstrating its use as a non-invasive robust technique to estimate pigment concentration in studies of coral reef biodiversity and health. PMID:26619210

  13. Changes in Species, Areal Cover, and Production of Moss across a Fire Chronosequence in Interior Alaska

    USGS Publications Warehouse

    Harden, J.W.; Munster, J.; Manies, K.L.; Mack, M.C.; Bubier, J.L.

    2009-01-01

    In an effort to characterize the species and production rates of various upland mosses and their relationship to both site drainage and time since fire, annual net primary production of six common moss species was measured. Several stands located near Delta Junction, interior Alaska, were located. These stands ranged from one to 116 years since fire in well-drained (dry) and moderately to somewhat poorly drained (wet) black spruce (Picea mariana)-feathermoss systems. Moss species composition varied greatly during the fire cycle, with Ceratodon purpureus dominating the earliest years after a fire, Aulacomnium palustre dominating the transitional and older stages, and Hylocomium splendens dominating the oldest, mature sites. Polytrichum spp. was found at all sites. Average moss cover ranged from <10 percent in the youngest sites to almost 90 percent in the mature sites. Species from the genus Polytrichum were the most productive and contributed up to 30 g m2 of organic matter in one growing season. Least productive was Rhytidium rugosum, which contributed about 1.5 g m2 of organic matter in mature stands. Recovery of moss productivity after fire was not significantly different for wet and dry sites.

  14. Calculations of Asteroid Impacts into Deep and Shallow Water

    NASA Astrophysics Data System (ADS)

    Gisler, Galen; Weaver, Robert; Gittings, Michael

    2011-06-01

    kilometers from the impact point, and fallout from the initial splash can be extremely violent. There is some indication that near-field effects are more severe if the impact occurs in shallow water.

  15. A Modal Decomposition of the Rotating Shallow Water Equations

    NASA Astrophysics Data System (ADS)

    Poulin, Francis; Waite, Michael; Greig, Daniel

    2013-04-01

    The dynamics of the atmosphere and oceans are complicated because of the vast range of length and time scales involved. Understanding how energy cascades from the large to small scales is an outstanding problem in the field and of great interest. In any attempt to do this it is always necessary to specify the physical structure of the basis functions. Perhaps the most popular choice are Fourier modes, which are desirable because they 1) can form a complete basis; 2) are well understood because of the richness of Fourier analysis; and 3) are a basis for high-order spectral methods. This is a convenient choice but numerous other possibilities exist, such as polynomials and wavelets. All of these choices are generic in that they do not arise from the underlying physics of the waves and can usually be applied to virtually any problem. The motivation for this work stems from the idea that a better choice for basis functions should be dictated by the model equations. One relatively simple model that has often been used to looked at energy transfers between different length and time scales is the Rotating Shallow Water model (RSW). It is restrictive in that it only describes homogeneous fluids, however, because it can contain both fast gravity and slow Rossby waves it is a useful paradigm to study energy transfers between waves with vastly different scales. The pioneering work of Leith (1980) investigated the decomposition of the RSW into its linear modes and subsequently others have built on this to understand the modal structure of stratified flows. In these works the emphasis has been on f-plane and therefore the slow component was a vortical mode that does not propagate. In his original paper Leith points out that it would be interesting to extend his methodology to a beta-plane and in this talk we present results from our preliminary work to do just that. This is done numerically using spectral methods to find the most accurate solutions possible for a given number

  16. Shallow water simulations of Saturn's giant storms at different latitudes

    NASA Astrophysics Data System (ADS)

    García-Melendo, E.; Sánchez-Lavega, A.

    2017-04-01

    Shallow water simulations are used to present a unified study of three major storms on Saturn (nicknamed as Great White Spots, GWS) at different latitudes, polar (1960), equatorial (1990), and mid-latitude (2010) (Sánchez-Lavega, 2004; Sánchez-Lavega et al., 2011). In our model, the three GWS are initiated by introducing a Gaussian function pulse at the latitude of the observed phenomena with controlled horizontal size and amplitude. This function represents the convective source that has been observed to trigger the storm. A growing disturbance forms when the pulse reacts to ambient winds, expanding zonally along the latitude band of the considered domain. We then compare the modeled potential vorticity with the cloud field, adjusting the model parameters to visually get the closest aspect between simulations and observations. Simulations of the 2010 GWS (planetographic latitude ∼+40º, zonal velocity of the source ∼-30 m s-1) indicate that the Coriolis forces and the wind profile structure shape the disturbance generating, as observed, a long region to the east of the convective source with a high speed peripheral anticyclonic circulation, and a long-lived anticyclonic compact vortex accompanied by strong zonal advection on the southern part of the storm forming a turbulent region. Simulations of the equatorial 1990 GWS (planetographic latitude +12º-+5º, zonal velocity of the source 365-400 m s-1) show a different behavior because of the intense eastward jet, meridional shear at the equatorial region, and low latitude dynamics. A round shaped source forms as observed, with the rapid growth of a Kelvin-Helmholtz instability on the north side of the source due to advection and to the strong meridional wind shear, whereas at the storm latitude the disturbance grows and propagates eastward. The storm nucleus is the manifestation of a Rossby wave, while the eastward propagating planetary-scale disturbance is a gravity-Rossby wave trapped around the equator

  17. Toxicological assessment of aquatic ecosystems: application to watercraft contaminants in shallow water environments

    USGS Publications Warehouse

    Winger, P.V.; Kemmish, Michael J.

    2002-01-01

    Recreational boating and personal watercraft use have the potential to adversely impact shallow water systems through contaminant release and physical disturbance of bottom sediments. These nearshore areas are often already degraded by surface runoff, municipal and industrial effluents, and other anthropogenic activities. For proper management, information is needed on the level of contamination and environmental quality of these systems. A number of field and laboratory procedures can be used to provide this much needed information. Contaminants, such as metals, pesticides, polychlorinated biphenyls and polycyclic aromatic hydrocarbons, entering aquatic environments generally attach to particulate matter that eventually settles and becomes incorporated into the bottom sediments. Because bottom sediments serve as a sink and as a source for contaminants, environmental assessments generally focus on this matrix. While contaminant residues in sediments and sediment pore waters can reflect environmental quality, characteristics of sediment (redox potential, sediment/pore-water chemistry, acid volatile sulfides, percent organic matter, and sediment particle size) influence their bioavailability and make interpretation of environmental significance difficult. Comparisons of contaminant concentrations in pore water (interstitial water) and sediment with water quality criteria and sediment quality guidelines, respectively, can provide insight into potential biological effects. Laboratory bioaccumulation studies and residue concentrations in resident or caged biota also yield information on potential biological impacts. The usefulness of these measurements may increase as data are developed relating in-situ concentrations, tissue residue levels, and biological responses. Exposure of test organisms in situ or to field-collected sediment and pore water are additional procedures that can be used to assess the biological effects of contaminants. A battery of tests using multi-species

  18. Antimicrobial Activity of Marine Bacterial Symbionts Retrieved from Shallow Water Hydrothermal Vents.

    PubMed

    Eythorsdottir, Arnheidur; Omarsdottir, Sesselja; Einarsson, Hjorleifur

    2016-06-01

    Marine sponges and other sessile macro-organisms were collected at a shallow water hydrothermal site in Eyjafjörður, Iceland. Bacteria were isolated from the organisms using selective media for actinomycetes, and the isolates were screened for antimicrobial activity. A total of 111 isolates revealed antimicrobial activity displaying different antimicrobial patterns which indicates production of various compounds. Known test strains were grown in the presence of ethyl acetate extracts from one selected isolate, and a clear growth inhibition of Staphylococcus aureus was observed down to 0.1 % extract concentration in the medium. Identification of isolates shows different species of Actinobacteria with Streptomyces sp. playing the largest role, but also members of Bacilli, Alphaproteobacteria and Gammaproteobacteria. Sponges have an excellent record regarding production of bioactive compounds, often involving microbial symbionts. At the hydrothermal vents, however, the majority of active isolates originated from other invertebrates such as sea anemones or algae. The results indicate that antimicrobial assays involving isolates in full growth can detect activity not visible by other methods. The macro-organisms inhabiting the Eyjafjörður hydrothermal vent area host diverse microbial species in the phylum Actinobacteria with antimicrobial activity, and the compounds responsible for the activity will be subject to further research.

  19. Ambient Noise in Shallow Water: A Survey of the Unclassified Literature.

    DTIC Science & Technology

    1986-02-01

    hypothesis which would explain this observation is that the source of noise near the low 7. ..7.. ~~u-~m".. .- - p -~~* - %R -vi w - AlJ’ Wf % --’,Wkz...Shallow water ambient noise surprisingly flat (white) for high wind speed, in contrast to typical ambient noise spectra. p The difference is explained...taken * .. . . . . .. p .-... . . ..-.. :; ..- ..- ... ; .. ’...’~~. ... ".. .. ’.-.-...... . ..... - .... ...... ..... . .. . - 18 Shallow water ambient

  20. 3-D Sound Propagation and Acoustic Inversions in Shallow Water Oceans

    DTIC Science & Technology

    2011-09-01

    method is used to study canonical environmental models of shelfbreak front systems and nonlinear internal wave ducts. The WHOI 3D Parabolic-Equation...localization methods with normal mode theory have been established for localizing low frequency, broadband signals in a shallow water environment. Gauss ...approach for low-frequency broadband sound source localization in a shallow-water ocean is established. Gauss -Markov inverse theory is used in both

  1. Shallow Water Dynamics in the Arabian Gulf and Gulf of Oman

    DTIC Science & Technology

    2016-06-07

    Shallow Water Dynamics in the Arabian Gulf and Gulf of Oman Dr. Cheryl Ann Blain Naval Research Laboratory, Ocean Dynamics and Prediction Branch...of a circulation model for the Arabian Gulf and connecting waters that realistically predicts the complex, 3-D circulation and mixing patterns in the...number. 1. REPORT DATE 30 SEP 1999 2. REPORT TYPE 3. DATES COVERED 00-00-1999 to 00-00-1999 4. TITLE AND SUBTITLE Shallow Water Dynamics in

  2. Sonobuoy-Based, 3-D Acoustic Characterization of Shallow-Water Environments

    DTIC Science & Technology

    2015-09-30

    Shallow- Water Environments George V. Frisk Department of Ocean and Mechanical Engineering Florida Atlantic University SeaTech Campus 101 North Beach...TERM GOALS The long-term goal of this research is to increase our understanding of shallow water acoustic propagation and its relationship to the...three-dimensionally varying seabed and water column environments. OBJECTIVES The scientific objectives of this research are: (1) to develop high

  3. Array Receivers and Sound Sources for Three Dimensional Shallow Water Acoustic Field Experiments

    DTIC Science & Technology

    2016-12-06

    Water Acoustic Field Experiments NOOO 14-15-1-2893 Sc. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Sd. PROJECT NUMBER Ying Tsong-Lin 132893SP Se. TASK...testing. 1S. SUBJECT TERMS acoustics, shallow water , Arctic Ocean , 3-D acoustic propagation, shelfbreak 16. SECURITY CLASSIFICATION OF: R b...Approved f or public release; distribution is unlimited. Array Receivers and Sound Sources for Three-Dimensional Shallow- Water Acoustic Field

  4. A New Microbial Player on the Iron Redox Court of Shallow-Water Hydrothermal Vents

    NASA Astrophysics Data System (ADS)

    Perez-Rodriguez, I. M.; Rawls, M.; Coykendall, D. K.; Foustoukos, D.

    2015-12-01

    The Fe(III)/Fe(II) couple is thought to have been a significant early energy metabolism involved in some of the first biogeochemical processes on Earth (Weber et al., 2006). The early evolving and metal-rich nature of modern hydrothermal systems remain particularly significant for Fe-based activities (Vargas et al., 1998). Documented evidence from such systems show a variety of yet unknown microbial lineages potentially linked to the history of Fe (i.e., Meyer-Dombard and Amend, 2014). Here we describe a novel microbe that reduces Fe(III) at shallow-water hydrothermal vents in Milos Island, Greece. Our laboratory experiments show this strain, MAG-PB1T, to reduce Fe(III) between 30 - 70 °C, 0 - 50 g NaCl l-1 and pH 5.5 - 8.0. Shortest generation time occurred under optimal conditions (60 °C, ~1.8 g NaCl l-1, pH 6.0) with H2 as the energy source, CO2 as the carbon source and Fe(III) as electron acceptor. Its metabolic characteristics are, however, not limited to this pathway. Strain MAG-PB1T can also reduce Mn(IV), arsenate and selenate. Its use of at least 9 organic substrates as energy or carbon sources also demonstrates its mixotrophy. Phylogenetic 16S rRNA gene analyses place strain MAG-PB1T within the Deltaproteobacteria, with the closest match (99%) being an uncultured microbe from hydrothermal springs in Ambitle Island, Papua New Guinea (Meyer-Dombard and Amend, 2014). Its next closest match (97%) is Deferrisoma camini, isolated from a deep-sea vent in the Eastern Lau Spreading Center (Slobodkina et al. 2012). Our strain represents a novel species, which we named Deferrisoma paleochoriense. The occurrence of D. paleochoriense in the shallow-water vents of Milos and Ambitle islands coincides with high arsenic, iron and sulfide contents (Akerman et al., 2011; Price et al., 2013; Yücel et al., 2013). Consequently, our study provides important physiological and metabolic evidence of the feedback between metal chemistry and life in hydrothermal sytems rich in

  5. Historical abundance and morphology of Didymosphenia species in Naknek Lake, Alaska

    USGS Publications Warehouse

    Pite, D.P.; Lane, K.A.; Hermann, A.K.; Spaulding, S.A.; Finney, B.P.

    2009-01-01

    Since the 1980s, nuisance blooms of Didymosphenia geminata (Lyngbye) M. Schmidt have been documented in sites that are warmer and more mesotrophic than historical records indicate. While the invasion of D. geminata in New Zealand is well documented, it is less clear whether nuisance blooms in North America are a new phenomenon. In order to test the hypothesis that D. geminata blooms have increased in recent years, we examined the historical record of this species in sediments of Naknek Lake, in Katmai National Park, Alaska. Chronological control was established by relating the presence of two ash layers to known volcanic eruptions. We identified two species of Didymosphenia within the sediment record: D. geminata and D. clavaherculis (Ehrenberg) Metzeltin et Lange-Bertalot. This is the first published record of D. clavaherculis in North America. We found no statistically significant change in the numerical presence of D. geminata or D. clavaherculis, as a group, in Naknek Lake between the years 1218 and 2003. While there has been no sudden, or recent, increase in abundance of Didymosphenia in Naknek Lake, morphological features of D. geminata populations in Naknek Lake are distinct compared to morphological features of D. geminata in streams containing nuisance blooms from sites in North America and New Zealand. Variance in the morphology of Didymosphenia cells may help determine relationships between distinct sub-populations and establish the history of habitat invasion.

  6. Habitat values for artificial oyster ( Crassostrea ariakensis) reefs compared with natural shallow-water habitats in Changjiang River estuary

    NASA Astrophysics Data System (ADS)

    Quan, Weimin; Zheng, Lin; Li, Beijun; An, Chuanguang

    2013-09-01

    Oyster reefs have an equivalent, complex 3-dimensional structure to vegetated habitats and may provide similar functions in estuarine environments. Nevertheless, few studies have compared oyster reefs with adjacent natural shallow-water habitats. Here the resident benthic macroinvertebrate communities in an artificial oyster ( Crassostrea ariakensis) reef and in adjacent natural estuarine shallow-water habitats (salt marsh, intertidal mudflat, and subtidal soft bottom) in the Changjiang (Yangtze) River estuary were described. The mean total densities and biomass, Margalef's species richness, Pielou's evenness and Shannon-Weaver biodiversity indices of the resident benthic macroinvertebrate communities differed significantly among the habitats. Significantly higher densities and biomass of benthic macroinvertebrates occurred in the oyster reef compared with the other three habitats. Ordination plots showed a clear separation in benthic macroinvertebrate communities among the four habitat types. The results demonstrated that the artificial oyster reef supported distinct and unique benthic communities, playing an important role in the complex estuarine habitat by supplying prey resources and contributing to biodiversity. In addition, the results suggested that the oyster reef had been restored successfully.

  7. How to react to shallow water hydrodynamics: The larger benthic foraminifera solution.

    PubMed

    Briguglio, Antonino; Hohenegger, Johann

    2011-11-01

    Symbiont-bearing larger benthic foraminifera inhabit the photic zone to provide their endosymbiotic algae with light. Because of the hydrodynamic conditions of shallow water environments, tests of larger foraminifera can be entrained and transported by water motion. To resist water motion, these foraminifera have to build a test able to avoid transport or have to develop special mechanisms to attach themselves to substrate or to hide their test below sediment grains. For those species which resist transport by the construction of hydrodynamic convenient shapes, the calculation of hydrodynamic parameters of their test defines the energetic input they can resist and therefore the scenario where they can live in. Measuring the density, size and shape of every test, combined with experimental data, helps to define the best mathematical approach for the settling velocity and Reynolds number of every shell. The comparison between water motion at the sediment-water interface and the specimen-specific settling velocity helps to calculate the water depths at which, for a certain test type, transport, deposition and accumulation may occur. The results obtained for the investigated taxa show that the mathematical approach gives reliable results and can discriminate the hydrodynamic behaviour of different shapes. Furthermore, the study of the settling velocities, calculated for all the investigated taxa, shows that several species are capable to resist water motion and therefore they appear to be functionally adapted to the hydrodynamic condition of its specific environment. The same study is not recommended on species which resist water motion by adopting hiding or anchoring strategies to avoid the effect of water motion.

  8. Ecological Turnover of Shallow Water Carbonate Producers Following the Paleocene-Eocene Thermal Maximum

    NASA Astrophysics Data System (ADS)

    Weiss, A.; Martindale, R. C.

    2015-12-01

    Modern coral reef ecosystems are under threat from global climate change (and associated, synergistic stresses) and local environmental degradation. Therefore, it is important for ecologists to understand how ecosystems adapt and recover from climate change. The fossil record provides excellent case studies of similar events, such as the Paleocene-Eocene Thermal Maximum (PETM). Although Paleocene and Eocene shallow water carbonates have not received the same degree of attention as the deep-water record, the PETM provides an opportunity to study the role of alternative stable states in maintaining the health and diversity of shallow water carbonate environments. It is generally accepted that during the PETM there is a transition from reef systems to foraminiferal shoals as the dominant shallow water carbonate producers. In fact, previous work has documented this interval as one of the major metazoan reef collapses of the Phanerozoic. This study fills an important gap in the shallow-water PETM record by quantitatively measuring the changes in carbonate production and ecology of 15 localities as they shift from coral reefs to foraminiferal shoal. The quantitative and semi-quantitative analysis is accomplished by using data from the PaleoReefs database and a simple carbonate production calculation to estimate the productivity of the shallow water system. Ecological data are gathered through a literature review of the localities. The results of this study will enable a better understanding of how modern reefs may react to global climate and environmental change.

  9. Adaptation to deep-sea methane seeps from Cretaceous shallow-water black shale environments?

    NASA Astrophysics Data System (ADS)

    Kiel, Steffen; Wiese, Frank; Titus, Alan

    2013-04-01

    Sulfide-enriched environments in shallow water were considered as sites where animals acquire pre-adaptations enabling them to colonize deep-sea hydrothermal vents and seeps or where they survived extinction events in their deep-sea habitats. Here we present upper Cenomanian (early Late Cretaceous) shallow-water seep communities from the Tropic Shale in the Western Interior Seaway, USA, that lived during a time of extremely warm deep-water temperatures, which supposedly facilitates adaptations to the deep sea, and time-equivalent with a period of widespread oceanic and photic zone anoxia (OAE 2) that supposedly extinguished deep-water vent and seep faunas. Contrary to the expectation, the taxa inhabiting the Tropic Shale seeps were not found at any coeval or younger deep-water seep or vent deposit. This suggests that (i) pre-adaptations for living at deep-sea vents and seeps do not evolve at shallow-water methane seeps, and probably also not in sulfide-rich shallow-water environments in general; (ii) a low temperature gradient from shallow to deep water does not facilitate onshore-offshore adaptations to deep-sea vents and seeps; and (iii) shallow-water seeps did not act as refuges for deep-sea vent and seep animals. We hypothesize that the vast majority of adaptations to successfully colonize deep-sea vents and seeps are acquired below the photic zone.

  10. Dependence of waterbirds and shorebirds on shallow-water habitats in the Mid-Atlantic coastal region: An ecological profile and management recommendations

    USGS Publications Warehouse

    Erwin, R.M.

    1996-01-01

    Waterbirds (waterfowl, colonially nesting wading and seabirds, ospreys [Pandion haliaetus], and bald eagles [Haliaeetus leucocephalus]) and shorebirds (sandpipers, plovers, and relatives) may constitute a large fraction of the top level carnivore trophic component in many shallow-water areas of the mid-Atlantic region. The large biomass of many species (>1 kg body mass for the two raptors and some waterfowl) and enormous populations (e.g., >1 million shorebirds in late May in parts of Delaware Bay) reveal the importance of waterbirds as consumers and as linkages in nutrient flux in many shallow-water habitats. Salt and brackish marsh shallow-water habitats, including marsh pannes and tidal pools and creeks as well as constructed impoundments, are used intensively during most months of the year; in fall and winter, mostly by dabbling ducks, in spring and summer by migrant shorebirds and breeding colonial wading birds and seabirds. In adjacent estuaries, the intertidal flats and littoral zones of shallow embayments are heavily used by shorebirds, raptors, and colonial waterbirds in the May to September periods, with use by duck and geese heaviest from October to March. With the regional degradation of estuarine habitats and population declines of many species of waterbirds in the past 20 yr, some management recommendations relevant to shallow waters include: better protection, enhancement, and creation of small bay islands (small and isolated to preclude most mammalian predators) for nesting and brooding birds, especially colonial species; establishment of sanctuaries from human disturbance (e.g., boating, hunting) both in open water (waterfowl) and on land, better allocation of sandy dredged materials to augment islands or stabilize eroding islands; improvement in water management of existing impoundments to ensure good feeding, resting, and nesting opportunities for all the waterbirds, support for policies to preclude point and nonpoint source runoff of chemicals

  11. Examining mechanisms in the final stages of the elimination of boreal tree species on vulnerable sites in boreal Alaska

    NASA Astrophysics Data System (ADS)

    Juday, G. P.; Jess, R.; Alix, C. M.; Verbyla, D.

    2015-12-01

    The boreal forest of Alaska and western Canada exist in a complex mosaic of environments determined by elevation, aspect of exposure, and longitudinal and latitudinal gradients of change from warm, dry continental to maritime-influenced conditions. This forest region is largely made up of trees with two growth responses to temperature increases. Trees that decrease in growth are termed negative responders, and occupy warm, dry sites at low elevations. Trees that increase in radial growth are termed positive responders, and are largely in western Alaska, and at high elevation of the Brooks and Alaska Ranges. Since the Pacific climate regime shift of the 1970s, mature trees at low elevation sites have experienced increasing climate stress in several quasi-decadal cycles of intensifying drought stress. NDVI trends and tree ring records demonstrating radial growth decline are coherent. Phenological monitoring of spruce height growth also indicates that depletion of spring soil moisture is a critical process driven by the interaction of early warm season temperatures and precipitation. Novel biotic disturbance agents including spruce budworm, outbreaks of which are triggered by warm temperature anomalies related to its biology, and aspen leaf miner are depressing realized growth below climatically predicted levels, suggesting a pathway by which tree death is likely to occur before absolute temperature limits. As a result, insect outbreaks are degrading the otherwise strong long-term climate signal in Alaska boreal trees. However, young tree (> 40 yrs.) regeneration generally does not yet display the symptoms of acute high temperature stress. Overall, on these vulnerable sites, if temperature increases similar to the past 40 years continue, long term survival prospects are questionable because the climate conditions would be outside the limits that have historically defined the species ranges of aspen, Alaska birch, and black and white spruce.

  12. Helminth communities of three sympatric species of shorebirds (Charadrii) from four summer seasons at Bristol Bay, Alaska.

    PubMed

    Canaris, Albert G; Kinsella, John M

    2007-06-01

    Helminth communities in sympatric black turnstones (Arenaria melanocephala), ruddy turnstones (Arenaria interpres), and dunlin (Calidris alpina) were examined over 4 summers in Bristol Bay, Alaska. The compound community, made up of component communities of all 3 species of hosts for 4 summer seasons (n=164), consisted of 43 helminth species, with cestodes, especially Anomotaenia clavigera, accounting for 47% of the helminth species and 95% of the abundance. The black turnstone had significantly higher species richness and abundance than either the ruddy turnstone or dunlin. The congeneric black and ruddy turnstone component communities were the most similar, and the dunlin's was the least similar. New helminth species continued to be acquired in all 3 host species during years 2 to 4. There was no significant difference for abundance among sample years for each of the 3 species of host. The 3 component communities all included a predictable suite of helminths with 1 dominant species and 4 to 5 associates, a large number of less-predictable species, and a greater prevalence and abundance of cestode species. Consistencies over time included high diversity, low evenness, low species richness (<5), and continued recruitment of small numbers of helminth species with low prevalence and abundance. There was minimal circulation of helminth species between the dunlin and the 2 turnstone species, indicating a considerable degree of specialization, particularly among species of cestodes.

  13. Blue-winged teals swim in shallow water

    NASA Technical Reports Server (NTRS)

    1999-01-01

    A pair of blue-winged teals glide through the waters of the Merritt Island National Wildlife Refuge, which shares a boundary with Kennedy Space Center. Inhabiting marshes, shallow ponds and lakes from British Columbia, Quebec and Newfoundland to North Carolina, the Gulf Coast and southern California, the teal winters as far south as South America. The 92,000-acre refuge is a habitat for more than 310 species of birds, 25 mammals, 117 fishes and 65 amphibians and reptiles. The marshes and open water of the refuge also provide wintering areas for 23 species of migratory waterfowl, as well as a year-round home for great blue herons, great egrets, wood storks, cormorants, brown pelicans and other species of marsh and shore birds.

  14. Radar imaging of shallow water bathymetry: A case study in the Yangtze Estuary

    NASA Astrophysics Data System (ADS)

    Yu, Peng; Johannessen, Johnny A.; Kudryavtsev, Vladimir; Zhong, Xiaojing; Zhou, Yunxuan

    2016-12-01

    This study focuses on 2-dimensional (2-D) radar imaging of bathymetric features in the shallow water of the Yangtze Estuary using synthetic aperture radar (SAR) observations and model simulations. A validated 2-D shallow water numerical model simulates the barotropic current velocity, and the simulated current fields together with the relevant parameters of radar observations are then invoked in the radar imaging model as the input. The results show that variations in the simulated image intensity are mainly dominated by distinct radar backscatter anomalies caused by wave-current interactions in the vicinity of rapidly changing underwater topographies. The comparison between the simulated and observed SAR images shows a reasonable agreement, demonstrating that our approach may be implemented to monitor changes in the shallow water bathymetry of the Yangtze Estuary in the future.

  15. Marine bird and cetacean associations with bathymetric habitats and shallow-water topographies: implications for trophic transfer and conservation

    NASA Astrophysics Data System (ADS)

    Yen, Peggy P. W.; Sydeman, William J.; Hyrenbach, K. David

    2004-09-01

    We investigated the aggregative response of marine birds and cetaceans to bathymetric features in central California over 4 years, 1996-1997 and 2001-2002. A total of 1700 km 2 of ocean habitat was surveyed over six cruises. We considered the distribution of the most abundant marine birds and mammals in relation to bathymetry. We focused our analyses on eight focal taxa: Cassin's auklet ( Ptychoramphus aleuticus), common murre ( Uria aalge), sooty shearwater ( Puffinus grieus), phalarope species (red, and red-necked: Phalaropus fulicaria, Phalaropus lobatus), Dall's porpoise ( Phocoenoides dalli), Pacific white-sided dolphin ( Lagenorhynchus obliquidens), humpback whale ( Megaptera novaeangliae), and Risso's dolphin ( Grampus griseus). We evaluated associations of top predators with seven bathymetric indices and three distance measurements to shallow-water topographies. The bathymetric descriptors included (1) median depth, (2) depth coefficient of variation, (3) contour index, and shortest distance to (4) the mainland, (5) the continental shelf-break (200-m isobath), (6) the continental slope (1000-m isobath), and (7) pelagic waters (3000-m isobath). The measurements of shallow water topographies included the shortest distance to: (8) the Cordell Bank seamount, (9) the Farallon Island Archipelago (a breeding colony for auklets and murres), and (10) Monterey Canyon. We documented two instances of spatial autocorrelation (for Cassin's auklet and common murre) at lags (distances) of 0-3 and 3-9 km, respectively, and accounted for this spatial pattern in analyses of habitat associations. We found similar relationships between cetaceans and bathymetric features at both interannual and weekly time scales. Seabirds revealed both persistent and variable relationships through time. For the resident breeding murres, we detected an interannual trend in habitat use, with these birds shifting their distribution offshore over time. Our study demonstrates that resident and

  16. Three-dimensional mapping of evolving internal waves during the Shallow Water 2006 experiment.

    PubMed

    Badiey, Mohsen; Wan, Lin; Song, Aijun

    2013-07-01

    Detailed knowledge of sound speed profiles and the sound speed profile's spatial and temporal variability resulting from internal waves (IWs) are indispensable to investigating significant acoustic field fluctuations in shallow water. A strategy to obtain a time-varying, three-dimensional (3D) IW temperature field is presented. It uses two types of simultaneous measurements: dense observations from a farm of thermistor strings and IW surface expressions from a ship-based radar. Using data from the Shallow Water 2006 experiment, the temperature field, over multiple kilometers in range, was reconstructed and, fed to a 3D acoustic model to demonstrate IW impacts on acoustic propagation.

  17. Frequency dependence and intensity fluctuations due to shallow water internal waves.

    PubMed

    Badiey, Mohsen; Katsnelson, Boris G; Lynch, James F; Pereselkov, Serguey

    2007-08-01

    A theory and experimental results for sound propagation through an anisotropic shallow water environment are presented to examine the frequency dependence of the scintillation index in the presence of internal waves. The theory of horizontal rays and vertical modes is used to establish the azimutal and frequency behavior of the sound intensity fluctuations, specifically for shallow water broadband acoustic signals propagating through internal waves. This theory is then used to examine the frequency dependent, anisotropic acoustic field measured during the SWARM'95 experiment. The frequency dependent modal scintillation index is described for the frequency range of 30-200 Hz on the New Jersey continental shelf.

  18. A moist Boussinesq shallow water equations set for testing atmospheric models

    SciTech Connect

    Zerroukat, M. Allen, T.

    2015-06-01

    The shallow water equations have long been used as an initial test for numerical methods applied to atmospheric models with the test suite of Williamson et al. being used extensively for validating new schemes and assessing their accuracy. However the lack of physics forcing within this simplified framework often requires numerical techniques to be reworked when applied to fully three dimensional models. In this paper a novel two-dimensional shallow water equations system that retains moist processes is derived. This system is derived from three-dimensional Boussinesq approximation of the hydrostatic Euler equations where, unlike the classical shallow water set, we allow the density to vary slightly with temperature. This results in extra (or buoyancy) terms for the momentum equations, through which a two-way moist-physics dynamics feedback is achieved. The temperature and moisture variables are advected as separate tracers with sources that interact with the mean-flow through a simplified yet realistic bulk moist-thermodynamic phase-change model. This moist shallow water system provides a unique tool to assess the usually complex and highly non-linear dynamics–physics interactions in atmospheric models in a simple yet realistic way. The full non-linear shallow water equations are solved numerically on several case studies and the results suggest quite realistic interaction between the dynamics and physics and in particular the generation of cloud and rain. - Highlights: • Novel shallow water equations which retains moist processes are derived from the three-dimensional hydrostatic Boussinesq equations. • The new shallow water set can be seen as a more general one, where the classical equations are a special case of these equations. • This moist shallow water system naturally allows a feedback mechanism from the moist physics increments to the momentum via buoyancy. • Like full models, temperature and moistures are advected as tracers that interact

  19. Three-Dimensional Shallow Water Adaptive Hydraulics (ADH-SW3): Turbulence Closure

    DTIC Science & Technology

    2015-06-01

    ER D C/ CH L CR -1 5- 1 Three-Dimensional Shallow Water Adaptive Hydraulics (ADH-SW3): Turbulence Closure Co as ta l a nd H yd ra ul ic...military engineering, geospatial sciences, water resources, and environmental sciences for the Army, the Department of Defense, civilian agencies, and our...library at http://acwc.sdp.sirsi.net/client/default. ERDC/CHL CR-15-1 June 2015 Three-Dimensional Shallow Water Adaptive Hydraulics (ADH-SW3

  20. 76 FR 79620 - Fisheries of the Exclusive Economic Zone Off Alaska; Gulf of Alaska; Proposed 2012 and 2013...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-22

    ... be obtained from http://www.regulations.gov or from the Alaska Region Web site at http...'s Web site at http://alaskafisheries.noaa.gov/npfmc . The draft 2011 SAFE report for the GOA is... trawl PSC limits between the deep-water and shallow-water fisheries, limits for non-exempt...

  1. Preliminary results from a shallow water benthic grazing study

    USGS Publications Warehouse

    Jones, N.L.; Monismith, Stephen G.; Thompson, Janet K.

    2005-01-01

    Despite great improvements in our knowledge on the effects of benthic grazers on seston concentrations in water columns, the effects of different hydrodynamic conditions on grazing rates has not been formulated. This makes it difficult to assess the system-wide effect of the benthic ecosystem on phytoplankton concentrations. Furthermore, it affects our ability to predict the potential success of a benthic species, such as the invasive clams Corbicula fluminea and Potamocorbula amurensis. This paper presents the preliminary results of a control volume approach to elucidate the effect of different hydrodynamic conditions on the grazing rates of Corbicula fluminea.

  2. 77 FR 41332 - Fisheries of the Exclusive Economic Zone Off Alaska; Arrowtooth Flounder, Flathead Sole, Rex Sole...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-13

    ... Economic Zone Off Alaska; Arrowtooth Flounder, Flathead Sole, Rex Sole, Deep-Water Flatfish, and Shallow- Water Flatfish in the Gulf of Alaska Management Area AGENCY: National Marine Fisheries Service (NMFS...: NMFS is prohibiting directed fishing for arrowtooth flounder, flathead sole, rex sole,...

  3. Three Dimensional Shallow Water Adaptive Hydraulics (ADH-SW3): Waterborne Vessels

    DTIC Science & Technology

    2015-10-01

    currents and provided analytical tools to describe the effects of these currents on the hydrodynamics of the water body. Stockstill et al. (1999...accurately simulated. In this technical note the authors expand the two-dimensional (2D) shallow water implementation presented by Stockstill et al

  4. Range-Dependent Acoustic Propagation in Shallow Water with Elastic Bottom Effects

    DTIC Science & Technology

    2011-09-01

    interacting acoustic signals in shallow water for 1-D. Henrik Schmidt’s OASES program, a direct descendent of the original SAFARI, has solved the 1...D problem for isotropic elastic bottoms. OASES is efficient, can accept Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting

  5. Temporal sound field fluctuations in the presence of internal solitary waves in shallow water.

    PubMed

    Katsnelson, Boris G; Grigorev, Valery; Badiey, Mohsen; Lynch, James F

    2009-07-01

    Temporal variations of intensity fluctuations are presented from the SWARM95 experiment. It is hypothesized that specific features of these fluctuations can be explained by mode coupling due to the presence of an internal soliton moving approximately along the acoustic track. Estimates are presented in conjunction with theoretical consideration of the shallow water waveguide.

  6. SWIM: A Semi-Analytical Ocean Color Inversion Algorithm for Optically Shallow Waters

    NASA Technical Reports Server (NTRS)

    McKinna, Lachlan I. W.; Werdell, P. Jeremy; Fearns, Peter R. C. S.; Weeks, Scarla J.; Reichstetter, Martina; Franz, Bryan A.; Shea, Donald M.; Feldman, Gene C.

    2014-01-01

    Ocean color remote sensing provides synoptic-scale, near-daily observations of marine inherent optical properties (IOPs). Whilst contemporary ocean color algorithms are known to perform well in deep oceanic waters, they have difficulty operating in optically clear, shallow marine environments where light reflected from the seafloor contributes to the water-leaving radiance. The effect of benthic reflectance in optically shallow waters is known to adversely affect algorithms developed for optically deep waters [1, 2]. Whilst adapted versions of optically deep ocean color algorithms have been applied to optically shallow regions with reasonable success [3], there is presently no approach that directly corrects for bottom reflectance using existing knowledge of bathymetry and benthic albedo.To address the issue of optically shallow waters, we have developed a semi-analytical ocean color inversion algorithm: the Shallow Water Inversion Model (SWIM). SWIM uses existing bathymetry and a derived benthic albedo map to correct for bottom reflectance using the semi-analytical model of Lee et al [4]. The algorithm was incorporated into the NASA Ocean Biology Processing Groups L2GEN program and tested in optically shallow waters of the Great Barrier Reef, Australia. In-lieu of readily available in situ matchup data, we present a comparison between SWIM and two contemporary ocean color algorithms, the Generalized Inherent Optical Property Algorithm (GIOP) and the Quasi-Analytical Algorithm (QAA).

  7. Sugarcane Response to Nitrogen Fertilization on a Histosol with shallow Water Table and Periodic Flooding

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sugarcane (Saccharum spp.) is routinely exposed to periodic floods and shallow water tables on Histosols in the Everglades Agricultural Area (EAA) of Florida. Through microbial oxidation, these soils provide excess N for sugarcane, but it is not known if supplemental N would improve yields when micr...

  8. Range-Dependent Acoustic Propagation in Shallow Water with Elastic Bottom Effects

    DTIC Science & Technology

    2014-09-30

    JASA. This article documents the incorporation of seismic-like sources into the PE propagation model work important for ocean acoustic signals...1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Range-Dependent Acoustic Propagation in Shallow Water...quantitative forward modeling in range dependent, bottom-interacting acoustic propagation including sediment anisotropy and anelasticty. OBJECTIVES

  9. On a Moving Mesh Method Applied to the Shallow Water Equations

    NASA Astrophysics Data System (ADS)

    Felcman, J.; Kadrnka, L.

    2010-09-01

    The moving mesh method is applied to the numerical solution of the shallow water equations. The original numerical flux of the Vijayasundaram type is used in the finite volume method. The mesh adaptation procedure is described. The relevant numerical examples are presented.

  10. Questions Student Ask: Why Is It Harder to Paddle a Canoe in Shallow Water?

    ERIC Educational Resources Information Center

    Physics Teacher, 1985

    1985-01-01

    Explains the effect that depth of water has on the speed of Olympic-style racing canoes and kayaks. Indicates that canoes are harder to paddle in shallow water because the skin friction drag increases appreciable when the water depth decreases. (DH)

  11. Applying the Delay-Curve Hough Transform To Shallow-Water Environments,

    DTIC Science & Technology

    2007-11-02

    shallow-water environments. The GAMARAY model, an eigenray -based sound propagation model, was used to produce the sound field. Even though beyond some...short ranges the direct propagation path disappears and the dominant eigenrays are due to multipath, the correlation traces still maintain the shape of

  12. Range-Dependent Acoustic Propagation in Shallow Water with Elastic Bottom Effects

    DTIC Science & Technology

    2015-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Range-Dependent Acoustic Propagation in Shallow Water...bottom-interacting acoustic propagation including sediment anisotropy and anelasticty. OBJECTIVES The specific objectives of this research...are to develop practical theoretical and software tools for employing a fully elastic version of two-way coupled modes for modeling seismo- acoustic

  13. Integrability Test and Travelling-Wave Solutions of Higher-Order Shallow- Water Type Equations

    NASA Astrophysics Data System (ADS)

    Maldonado, Mercedes; Molinero, María Celeste; Pickering, Andrew; Prada, Julia

    2010-04-01

    We apply the Weiss-Tabor-Carnevale (WTC) Painlevé test to members of a sequence of higher-order shallow-water type equations. We obtain the result that the equations considered are non-integrable, although compatibility conditions at real resonances are satisfied. We also construct travelling-wave solutions for these and related equations.

  14. New shallow water table depth algorithm in SWAT2005: recent modifications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The proximity of the shallow water table depth (wtd) to the soil surface impacts agricultural production, farm machine trafficability, and water quality due to agricultural chemical transport and soil salinity. Therefore, it is essential for hydrologic models to accurately simulate wtd. Recently, an...

  15. Transition Funding for the Shallow Water Integrated Mapping System (SWIMS) and Modular Microstructure Profiler (MMP)

    DTIC Science & Technology

    2014-09-30

    Mapping System ( SWIMS ) and Modular Microstructure Profiler (MMP) Matthew H. Alford Scripps Institution of Oceanography 9500 Gilman Drive, mail code...performance of operational and climate models, as well as for understanding local problems such as pollutant dispersal and biological productivity. SWIMS ...moored profiling instruments. OBJECTIVES • Transition the Shallow Water Integrated Mapping System ( SWIMS ) and Modular Microstructure Profiler

  16. Metabolic and Cardiovascular Response to Shallow Water Exercise in Young and Older Women.

    ERIC Educational Resources Information Center

    Campbell, Jennifer A.; D'Acquisto, Leo J.; D'Acquisto, Debra M.; Cline, Michael G.

    2003-01-01

    Compared the metabolic and cardiovascular responses of young and older women while performing shallow water exercise (SWE). Overall, SWE elicited metabolic and cardiovascular responses that met American College of Sports Medicine's guidelines for establishing health benefits. Older females self-selected a greater relative exercise intensity during…

  17. Higher Order Corrections for Shallow-Water Solitary Waves: Elementary Derivation and Experiments

    ERIC Educational Resources Information Center

    Halasz, Gabor B.

    2009-01-01

    We present an elementary method to obtain the equations of the shallow-water solitary waves in different orders of approximation. The first two of these equations are solved to get the shapes and propagation velocities of the corresponding solitary waves. The first-order equation is shown to be equivalent to the Korteweg-de Vries (KdV) equation,…

  18. Modeling of Acoustic Field Statistics for Deep and Shallow Water Environments

    DTIC Science & Technology

    2014-09-30

    eddies, internal tides, internal waves, and fine structure ( spice ) are needed, while in the shallow water case a models of the random linear internal...waves and spice are lacking. APPROACH The approach to this research is to rigorously test acoustic fluctuation models using Monte Carlo

  19. Evaluation of 2D shallow-water model for spillway flow with a complex geometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although the two-dimensional (2D) shallow water model is formulated based on several assumptions such as hydrostatic pressure distribution and vertical velocity is negligible, as a simple alternative to the complex 3D model, it has been used to compute water flows in which these assumptions may be ...

  20. Shallow-water reef ophiuroids (Echinodermata: Ophiuroidea) of Réunion (Mascarene Islands), with biogeographic considerations.

    PubMed

    Boissin, Emilie; Hoareau, Thierry B; Paulay, Gustav; Bruggemann, J Henrich

    2016-04-06

    Despite their importance in marine biodiversity, invertebrates are far less studied than vertebrates. Given the current global biodiversity crisis and insufficient taxonomic resources, sustained efforts need to be undertaken to assess species diversity, especially in the highly threatened 'biodiversity hotspots'. Réunion is a young volcanic island lying in the Mascarene Islands (south-western Indian Ocean, SWIO), a marine biodiversity hotspot. A substantial sampling effort was conducted around Réunion Island to document shallow water reef-associated ophiuroid (brittle-stars) diversity, a class recognised as the most diverse among echinoderms. A total of 33 species were documented, increasing the known species richness of the island by 56%. Findings include 15 new records for Réunion, 11 for the Mascarene Islands and 8 for the Indian Ocean. The most diverse family was Ophiocomidae, a family of large, abundant and conspicuous tropical species. Even in this well studied family, a new species was revealed by this survey. Morphological variants together with DNA sequence variations within several species revealed cryptic species. We compared our results with the known fauna of other Mascarene Islands and discuss biogeographic implications for the region.

  1. Exploring a Multiresolution Modeling Approach within the Shallow-Water Equations

    SciTech Connect

    Ringler, Todd D.; Jacobsen, Doug; Gunzburger, Max; Ju, Lili; Duda, Michael; Skamarock, William

    2011-11-01

    The ability to solve the global shallow-water equations with a conforming, variable-resolution mesh is evaluated using standard shallow-water test cases. While the long-term motivation for this study is the creation of a global climate modeling framework capable of resolving different spatial and temporal scales in different regions, the process begins with an analysis of the shallow-water system in order to better understand the strengths and weaknesses of the approach developed herein. The multiresolution meshes are spherical centroidal Voronoi tessellations where a single, user-supplied density function determines the region(s) of fine- and coarsemesh resolution. The shallow-water system is explored with a suite of meshes ranging from quasi-uniform resolution meshes, where the grid spacing is globally uniform, to highly variable resolution meshes, where the grid spacing varies by a factor of 16 between the fine and coarse regions. The potential vorticity is found to be conserved to within machine precision and the total available energy is conserved to within a time-truncation error. This result holds for the full suite of meshes, ranging from quasi-uniform resolution and highly variable resolution meshes. Based on shallow-water test cases 2 and 5, the primary conclusion of this study is that solution error is controlled primarily by the grid resolution in the coarsest part of the model domain. This conclusion is consistent with results obtained by others.When these variable-resolution meshes are used for the simulation of an unstable zonal jet, the core features of the growing instability are found to be largely unchanged as the variation in the mesh resolution increases. The main differences between the simulations occur outside the region of mesh refinement and these differences are attributed to the additional truncation error that accompanies increases in grid spacing. Overall, the results demonstrate support for this approach as a path toward

  2. A new genus and species of Thyasiridae (Mollusca, Bivalvia) from deep-water, Beaufort Sea, northern Alaska

    PubMed Central

    Valentich-Scott, Paul; Powell, Charles L.; II; Lorenson, Thomas D.; Edwards, Brian E.

    2014-01-01

    Abstract Bivalve mollusk shells were collected in 2350 m depth in the Beaufort Sea, Arctic Ocean off northern Alaska. Initial identification suggested the specimens were a member of the bivalve family Thyasiridae, but no known eastern Pacific or Arctic living or fossil thyasirid resembled these deep-water specimens. Comparisons were made with the type of the genera Maorithyas Fleming, 1950, Spinaxinus Oliver & Holmes, 2006, Axinus Sowerby, 1821, and Parathyasira Iredale, 1930. We determined the Beaufort Sea species represents a new genus, herein described as Wallerconcha. These specimens also represent a new species, herein named Wallerconcha sarae. These new taxa are compared with known modern and fossil genera and species of thyasirds. PMID:25589851

  3. Diversity and phylogenetic analyses of bacteria from a shallow-water hydrothermal vent in Milos island (Greece).

    PubMed

    Giovannelli, Donato; d'Errico, Giuseppe; Manini, Elena; Yakimov, Michail; Vetriani, Costantino

    2013-01-01

    Studies of shallow-water hydrothermal vents have been lagging behind their deep-sea counterparts. Hence, the importance of these systems and their contribution to the local and regional diversity and biogeochemistry is unclear. This study analyzes the bacterial community along a transect at the shallow-water hydrothermal vent system of Milos island, Greece. The abundance and biomass of the prokaryotic community is comparable to areas not affected by hydrothermal activity and was, on average, 1.34 × 10(8) cells g(-1). The abundance, biomass and diversity of the prokaryotic community increased with the distance from the center of the vent and appeared to be controlled by the temperature gradient rather than the trophic conditions. The retrieved 16S rRNA gene fragments matched sequences from a variety of geothermal environments, although the average similarity was low (94%), revealing previously undiscovered taxa. Epsilonproteobacteria constituted the majority of the population along the transect, with an average contribution to the total diversity of 60%. The larger cluster of 16S rRNA gene sequences was related to chemolithoautotrophic Sulfurovum spp., an Epsilonproteobacterium so far detected only at deep-sea hydrothermal vents. The presence of previously unknown lineages of Epsilonproteobacteria could be related to the abundance of organic matter in these systems, which may support alternative metabolic strategies to chemolithoautotrophy. The relative contribution of Gammaproteobacteria to the Milos microbial community increased along the transect as the distance from the center of the vent increased. Further attempts to isolate key species from these ecosystems will be critical to shed light on their evolution and ecology.

  4. Shallow water heterobranch sea slugs (Gastropoda: Heterobranchia) from the Región de Atacama, northern Chile

    PubMed Central

    Valdés, Ángel

    2016-01-01

    The coast of northern Chile has been sparsely studied in regards to its invertebrate fauna, with just a few works reviewing the distribution of local mollusks. This work presents a survey of the shallow water heterobranch sea slugs currently occurring around the port of Caldera (27 °S), in the Región de Atacama, northern Chile. Eight species of sea slugs were found in this study: Aplysiopsis cf. brattstroemi (Marcus, 1959), Baptodoris peruviana (d’Orbigny, 1837), Diaulula variolata (d’Orbigny, 1837), Doris fontainii d’Orbigny, 1837, Onchidella marginata (Couthouy in Gould, 1852), Phidiana lottini (Lesson, 1831), Tyrinna delicata (Abraham, 1877) and the new species Berthella schroedli sp. nov., described herein. All of the species found in the area are endemic to South America, having distributions in the southeastern Pacific and South Atlantic Oceans, from Ancash, Perú to Peninsula Valdés, Argentina, and two of them represent species which are endemic to the Chilean coasts (Aplysiopsis cf. brattstroemi and Berthella schroedli). The finding of a previously undescribed species emphasizes the need of further surveys, particularly in subtidal and deeper waters, in order to improve the knowledge on this neglected fauna in Atacama. PMID:27168975

  5. Shallow Water Hydrothermal Vents in the Gulf of California: Natural Laboratories for Multidisciplinary Research

    NASA Astrophysics Data System (ADS)

    Forrest, M.; Hilton, D. R.; Price, R. E.; Kulongoski, J. T.

    2015-12-01

    Modern and fossil examples of shallow water submarine hydrothermal vents occur throughout the Gulf of California. These sites offer important information about the processes involved in the extensional tectonics that created the Gulf of California and continue to shape the region to this day. Due to their accessibility, shallow water marine hydrothermal vents are far easier to access and study than their deeper analogs, and these settings can provide natural laboratories to study biogeochemical processes. Certain biogeochemical and biomineralizing processes occurring at shallow vents are very similar to those observed around deep-sea hydrothermal vents. In some cases, authigenic carbonates form around shallow vents. However, the hydrothermal precipitates are generally composed of Fe-oxyhydroxides, Mn-oxides, opal, calcite, pyrite and cinnabar, and their textural and morphological characteristics suggest microbial mediation for mineral deposition. Modern shallow-water hydrothermal vents also support complex biotic communities, characterized by the coexistence of chemosynthetic and photosynthetic organisms. These shallow vents are highly productive and provide valuable resources to local fishermen. Extant shallow water hydrothermal activity has been studied in Bahía Concepción, San Felipe, Punta Estrella, El Coloradito, Puertecitos, and around the Islas Encantadas. Discrete streams of gas bubbles are often discharged along with hot liquids at shallow water vents. The vent liquids generally exhibit lower salinities than seawater, and their isotopic compositions indicate that they contain meteoric water mixed with seawater. The composition of the shallow vent gas is primarily made up of CO2, but may also be enriched in N2, H2S, CH4, and other higher hydrocarbons. The geochemistry of these gases can be informative in determining the sources and processes involved in their generation. In particular, 3He/4He ratios may provide valuable information about the origin of

  6. Atlas of Relations Between Climatic Parameters and Distributions of Important Trees and Shrubs in North America - Alaska Species and Ecoregions

    USGS Publications Warehouse

    Thompson, Robert S.; Anderson, Katherine H.; Strickland, Laura E.; Shafer, Sarah L.; Pelltier, Richard T.; Bartlein, Patrick J.

    2006-01-01

    Climate is the primary factor in controlling the continental-scale distribution of plant species, although the relations between climatic parameters and species' ranges is only now beginning to be quantified. Preceding volumes of this atlas explored the continental-scale relations between climatic parameters and the distributions of woody plant species across all of the continent of North America. This volume presents similar information for important woody species, groups of species, and ecoregions in more detail for the State of Alaska. For these analyses, we constructed a 25-kilometer equal-area grid of modern climatic and bioclimatic parameters for North America from instrumental weather records. We obtained a digital representation of the geographic distribution of each species or ecoregion, either from a published source or by digitizing the published distributions ourselves. The presence or absence of each species or ecoregion was then determined for each point on the 25-kilometer grid, thus providing a basis for comparison of the climatic data with the geographic distribution of each species or ecoregion. The relations between climate and these distributions are presented in graphical and tabular form.

  7. Early life history pelagic exposure profiles of selected commercially important fish species in the Gulf of Alaska

    NASA Astrophysics Data System (ADS)

    Doyle, Miriam J.; Mier, Kathryn L.

    2016-10-01

    A synthesis of nearly four decades of ichthyoplankton survey data from the Gulf of Alaska was undertaken to provide the most comprehensive information available on the early life history ecology of five focal species: Pacific Cod (Gadus macrocephalus), Walleye Pollock (Gadus chalcogrammus), Pacific Ocean Perch (Sebastes alutus), Sablefish (Anoplopoma fimbria), and Arrowtooth Flounder (Atheresthes stomias). This analysis of historical data, along with information from published studies, is presented here in the form of ecological reviews of the species during their planktonic phase. The reviews include descriptions of temporal and spatial patterns of exposure to the environment, and interpretation regarding associated sensitivities to environmental forcing. On a temporal scale, patterns in abundance of eggs and larvae are synthesized that characterize seasonal exposure to the pelagic environment, and interannual variation that is presumed to incorporate responses to long-term environmental forcing. Spatial patterns are synthesized to identify horizontal and vertical extent of egg and larval distributions, delineate areas of primary larval habitat, and illuminate egg and larval drift pathways. The observed patterns are discussed with respect to characterizing species early life history strategies, identifying long-term adaptations to the Gulf of Alaska environment, and associated resilience and vulnerability factors that may modulate early life responses to environmental forcing in this region. For each species, gaps in knowledge are identified and are concerned primarily with the period of transition between the larval and juvenile stage, and feeding habits and ecology across seasons, habitats and sub-intervals of early ontogeny. These early life history reviews advance our ecological understanding of the pelagic phase, and fine-tune our focus for the investigation of potential response mechanisms to environmental forcing at appropriate, species-specific temporal

  8. Unexpectedly high diversity of Monoporella (Bryozoa: Cheilostomata) in the Aleutian Islands, Alaska: taxonomy and distribution of six new species.

    PubMed

    Dick, Matthew H

    2008-01-01

    The cheilostome bryozoan genus Monoporella is poorly resolved taxonomically; only four Recent species have been formally described, though several undescribed species have been reported in the literature. The literature indicates no more than five species in the genus occurring in any local region of the world, with one to three species in most regions where the genus has been reported. I examined bryozoans from 52 trawl catches in the western and western-central Aleutian Islands, Alaska, and found specimens of Monoporella in 12 of these samples. Study of these specimens by scanning electron microscopy (SEM) revealed six new species that are described herein: M. flexibila, M. elongata, M. gigantea, M. ellefsoni, M. seastormi, and M. aleutica. Two of the species have erect colony morphologies, a condition not previously reported in Monoporella. The species diversity of Monoporella appears to be greater in the Aleutians than in any other part of the world adequately surveyed. I discuss whether this apparent high diversity is an artifact due to insufficient sampling in the deep shelf zone, and present two hypotheses to explain this high diversity should it prove not to be an artifact: 1) the present high local diversity represents a relict of past high diversity occurring broadly around the North Pacific rim; and 2) a local radiation of Monoporella occurred in the Aleutian archipelago.

  9. Algorithmically scalable block preconditioner for fully implicit shallow-water equations in CAM-SE

    SciTech Connect

    Lott, P. Aaron; Woodward, Carol S.; Evans, Katherine J.

    2014-10-19

    Performing accurate and efficient numerical simulation of global atmospheric climate models is challenging due to the disparate length and time scales over which physical processes interact. Implicit solvers enable the physical system to be integrated with a time step commensurate with processes being studied. The dominant cost of an implicit time step is the ancillary linear system solves, so we have developed a preconditioner aimed at improving the efficiency of these linear system solves. Our preconditioner is based on an approximate block factorization of the linearized shallow-water equations and has been implemented within the spectral element dynamical core within the Community Atmospheric Model (CAM-SE). Furthermore, in this paper we discuss the development and scalability of the preconditioner for a suite of test cases with the implicit shallow-water solver within CAM-SE.

  10. Algorithmically scalable block preconditioner for fully implicit shallow-water equations in CAM-SE

    DOE PAGES

    Lott, P. Aaron; Woodward, Carol S.; Evans, Katherine J.

    2014-10-19

    Performing accurate and efficient numerical simulation of global atmospheric climate models is challenging due to the disparate length and time scales over which physical processes interact. Implicit solvers enable the physical system to be integrated with a time step commensurate with processes being studied. The dominant cost of an implicit time step is the ancillary linear system solves, so we have developed a preconditioner aimed at improving the efficiency of these linear system solves. Our preconditioner is based on an approximate block factorization of the linearized shallow-water equations and has been implemented within the spectral element dynamical core within themore » Community Atmospheric Model (CAM-SE). Furthermore, in this paper we discuss the development and scalability of the preconditioner for a suite of test cases with the implicit shallow-water solver within CAM-SE.« less

  11. Explicit large time-step schemes for the shallow water equations

    NASA Technical Reports Server (NTRS)

    Turkel, E.; Zwas, G.

    1979-01-01

    Modifications to explicit finite difference schemes for solving the shallow water equations for meteorological applications by increasing the time step for the fast gravity waves are analyzed. Terms associated with the gravity waves in the shallow water equations are treated on a coarser grid than those associated with the slow Rossby waves, which contain much more of the available energy and must be treated with higher accuracy, enabling a several-fold increase in time step without degrading the accuracy of the solution. The method is presented in Cartesian and spherical coordinates for a rotating earth, using generalized leapfrog, frozen coefficient, and Fourier filtering finite difference schemes. Computational results verify the numerical stability of the approach.

  12. The structure of raylike arrivals in a shallow-water waveguide.

    PubMed

    Roux, Philippe; Cornuelle, Bruce D; Kuperman, W A; Hodgkiss, W S

    2008-12-01

    Acoustic remote sensing of the oceans requires a detailed understanding of the acoustic forward problem. The results of a shallow-water transmission experiment between a vertical array of sources and a vertical array of receivers are reported. The source array is used to provide additional degrees of freedom to isolate and track raylike arrivals by beamforming over both source and receiver arrays. The coordinated source-receiver array processing procedure is presented and its effectiveness in an example of tracking raylike arrivals in a fluctuating ocean environment is shown. Many of these arrivals can be tracked over an hour or more and show slowly varying amplitude and phase. The use of a double-beamforming algorithm lays the foundation for shallow-water acoustic remote sensing using travel time and source and receive angles of selected eigenrays.

  13. Shallow-water seismoacoustic noise generated by tropical storms Ernesto and Florence.

    PubMed

    Traer, James; Gerstoft, Peter; Bromirski, Peter D; Hodgkiss, William S; Brooks, Laura A

    2008-09-01

    Land-based seismic observations of double frequency (DF) microseisms generated during tropical storms Ernesto and Florence are dominated by signals in the 0.15-0.5 Hz band. In contrast, data from sea floor hydrophones in shallow water (70 m depth, 130 km off the New Jersey coast) show dominant signals in the ocean gravity-wave frequency band, 0.02-0.18 Hz, and low amplitudes from 0.18 to 0.3 Hz, suggesting significant opposing wave components necessary for DF microseism generation were negligible at the site. Florence produced large waves over deep water while Ernesto only generated waves in coastal regions, yet both storms produced similar spectra. This suggests near-coastal shallow water as the dominant region for observed microseism generation.

  14. Initial value problem solution of nonlinear shallow water-wave equations.

    PubMed

    Kânoğlu, Utku; Synolakis, Costas

    2006-10-06

    The initial value problem solution of the nonlinear shallow water-wave equations is developed under initial waveforms with and without velocity. We present a solution method based on a hodograph-type transformation to reduce the nonlinear shallow water-wave equations into a second-order linear partial differential equation and we solve its initial value problem. The proposed solution method overcomes earlier limitation of small waveheights when the initial velocity is nonzero, and the definition of the initial conditions in the physical and transform spaces is consistent. Our solution not only allows for evaluation of differences in predictions when specifying an exact initial velocity based on nonlinear theory and its linear approximation, which has been controversial in geophysical practice, but also helps clarify the differences in runup observed during the 2004 and 2005 Sumatran tsunamigenic earthquakes.

  15. Multiwavelet Discontinuous Galerkin Accelerated ELP Method for the Shallow Water Equations on the Cubed Sphere

    SciTech Connect

    White III, James B; Archibald, Richard K; Evans, Katherine J; Drake, John

    2011-01-01

    In this paper we present a new approach to increase the time-step size for an explicit discontinuous Galerkin numerical method. The attributes of this approach are demonstrated on standard tests for the shallow-water equations on the sphere. The addition of multiwavelets to discontinuous Galerkin method, which has the benefit of being scalable, flexible, and conservative, provides a hierarchical scale structure that can be exploited to improve computational efficiency in both the spatial and temporal dimensions. This paper explains how combining a multiwavelet discontinuous Galerkin method with exact linear part time-evolution schemes, which can remain stable for implicit-sized time steps, can help increase the time-step size for shallow water equations on the sphere.

  16. Iterative Receiver in Time-Frequency Domain for Shallow Water Acoustic Channel

    NASA Astrophysics Data System (ADS)

    Zhao, Liang; Ge, Jianhua

    2012-03-01

    Inter-symbol interference (ISI) caused by multi-path propagation, especially in shallow water channel, degrades the performance of underwater acoustic (UWA) communication systems. In this paper, we combine soft minimum mean squared error (MMSE) equalization and the serially concatenated trellis coded modulation (SCTCM) decoding to develop an iterative receiver in time-frequency domain (TFD) for underwater acoustic point to point communications. Based on sound speed profile (SSP) measured in the lake and finite-element ray (FER) tracing method (Bellhop), the shallow water channel is constructed to evaluate the performance of the proposed iterative receiver. The results suggest that the proposed iterative receiver can reduce the calculation complexity of the equalizer and obtain better performance using less receiving elements.

  17. Nonlinear diffraction of waves by a submerged shelf in shallow water

    SciTech Connect

    Ertekin, R.C.; Becker, J.M.

    1996-12-31

    The diffraction of water waves by submerged obstacles in shallow water generally requires the use of a nonlinear theory since both dispersive and nonlinear effects are important. In this work, wave diffraction is studied in a numerical wave-tank using the Green-Naghdi (G-N) equations. Cnoidal waves are generated numerically by a wave maker situated at one end of a 2-dimensional numerical wave tank. At the downwave end of the tank, an open-boundary condition is implemented to simulate a wave-absorbing beach and thus to reduce reflections. The G-N equations are solved in the time-domain by employing a finite-difference method. The numerical method is applied to diffraction of cnoidal waves by a submerged shelf, or a sand bar, of considerable height relative to water depth. The predicted results are compared with the available experimental data which indicate the importance of nonlinearity for the shallow-water conditions.

  18. The lantern shark's light switch: turning shallow water crypsis into midwater camouflage

    PubMed Central

    Claes, Julien M.; Mallefet, Jérôme

    2010-01-01

    Bioluminescence is a common feature in the permanent darkness of the deep-sea. In fishes, light is emitted by organs containing either photogenic cells (intrinsic photophores), which are under direct nervous control, or symbiotic luminous bacteria (symbiotic photophores), whose light is controlled by secondary means such as mechanical occlusion or physiological suppression. The intrinsic photophores of the lantern shark Etmopterus spinax were recently shown as an exception to this rule since they appear to be under hormonal control. Here, we show that hormones operate what amounts to a unique light switch, by acting on a chromatophore iris, which regulates light emission by pigment translocation. This result strongly suggests that this shark's luminescence control originates from the mechanism for physiological colour change found in shallow water sharks that also involves hormonally controlled chromatophores: the lantern shark would have turned the initial shallow water crypsis mechanism into a midwater luminous camouflage, more efficient in the deep-sea environment. PMID:20410033

  19. Ocean Acoustic Propagation: Fluctuations and Coherence in Dynamically Active Shallow-Water Regions

    DTIC Science & Technology

    2011-03-04

    sponsored field programs. These were 1. The Littoral Environmental Acoustics Research portion of the ONR Shallow-Water 2006 experiment (SW06- LEAR ...cooled water on the shelf. In this particular frontal zone there can be a thin deep warm salty layer, capped by an inverted thermocline, on the near... deep thermocline (above the thin deep salty layer) both summer and winter. The South China Sea experiment area has multiple types of large nonlinear

  20. Dealing With Shallow-Water Flow in the Deepwater Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Ostermeier, R.

    2006-05-01

    Some of the Shell experience in dealing with the shallow-water flow problem in the Deepwater Gulf of Mexico (GOM) will be presented. The nature of the problem, including areal extent and over-pressuring mechanisms, will be discussed. Methods for sand prediction and shallow sediment and flow characterization will be reviewed. These include seismic techniques, the use of geo-technical wells, regional trends, and various MWD methods. Some examples of flow incidents with pertinent drilling issues, including well failures and abandonment, will be described. To address the shallow-water flow problem, Shell created a multi-disciplinary team of specialists in geology, geophysics, petrophysics, drilling, and civil engineering. The team developed several methodologies to deal with various aspects of the problem. These include regional trends and data bases, shallow seismic interpretation and sand prediction, well site and casing point selection, geo-technical well design and data interpretation, logging program design and interpretation, cementing design and fluids formulation, methods for remediation and mitigation of lost circulation, and so on. Shell's extensive Deepwater GOM drilling experience has lead to new understanding of the problem. Examples include delineation of trends in shallow water flow occurrence and severity, trends and departures in PP/FG, rock properties pertaining to seismic identification of sands, and so on. New knowledge has also been acquired through the use of geo-technical wells. One example is the observed rapid onset and growth of over-pressures below the mudline. Total trouble costs due to shallow water flow for all GOM operators almost certainly runs into the several hundred million dollars. Though the problem remains a concern, advances in our knowledge and understanding make it a problem that is manageable and not the "show stopper" once feared.

  1. Geoacoustic Inversion and Source Localization in a Randomly Fluctuating Shallow Water Environment

    DTIC Science & Technology

    2010-06-01

    with a standard deviation of 570 m. 2.2 SVV06 experiment data analysis: Sei whale localization Comparatively little is known about sei whale ...large number of sei whale calls were unexpectedly collected during the SW06 experiment, which introduced the first evidence of sei whales in this...shallow water region. Using the normal mode approach developed in this project, we are able to track the remote locations of these whales up to tens of

  2. Strong and Weak Lagrange-Galerkin Spectral Element Methods for the Shallow Water Equations

    DTIC Science & Technology

    2003-02-01

    Galerkin Spectral Element Methods for the Shallow Water Equations F . X. GIRALDO Naval Research Laboratory Monterey, CA 93943, U.S.A...edged. 0898-1221/03/$ - see front matter © 2003 Published by Elsevier Science Ltd. PII: 80898-1221(02)00330-9 Typeset by ANfS-TEX 98 F . X...resulting operator is then discretized using the standard finite-element method. This is the approach used by Bercovier and Pironneau [4], Bermejo [5

  3. Generalized energy and potential enstrophy conserving finite difference schemes for the shallow water equations

    NASA Technical Reports Server (NTRS)

    Abramopoulos, Frank

    1988-01-01

    The conditions under which finite difference schemes for the shallow water equations can conserve both total energy and potential enstrophy are considered. A method of deriving such schemes using operator formalism is developed. Several such schemes are derived for the A-, B- and C-grids. The derived schemes include second-order schemes and pseudo-fourth-order schemes. The simplest B-grid pseudo-fourth-order schemes are presented.

  4. Wave breaking and shock waves for a periodic shallow water equation.

    PubMed

    Escher, Joachim

    2007-09-15

    This paper is devoted to the study of a recently derived periodic shallow water equation. We discuss in detail the blow-up scenario of strong solutions and present several conditions on the initial profile, which ensure the occurrence of wave breaking. We also present a family of global weak solutions, which may be viewed as global periodic shock waves to the equation under discussion.

  5. Shallow Water Sediment Properties Derived from High-Frequency Shear and Interface Waves

    DTIC Science & Technology

    1992-04-10

    FREQUENCY SHEAR ONR N00014-88-C-1238 AND INTERFACE WAVES 6. AUTHOR(S) JOHN EWING, JERRY A. CARTER, GEORGE H. SUTTON AND NOEL BARSTOW 7. PERFORMING...B4. PAGES 4739--4762. APRIL 10. 1992 Shallow Water Sediment Properties Derived From High-Frequency Shear and Interface Waves JOHN EWING Woods Hole...calculating thickness. The amplitude falloff with range establishes a Q velocity gradients and penetration depths [ Nettleton . 19401 estimate of 40 in

  6. Acoustic Projectors for AUV and UUV Applications in Shallow Water Regions

    DTIC Science & Technology

    1999-04-01

    middle frequencies as those in the frequency range of 10 kHz to 100 kHz. Most current AUV or UUV applications feature either tonpilz (piston) transducers ...100 kHz band by driving the 100 lcHz resonant transducer with an inversely shaped transformer. The presentation will conclude with a discussion of the...future development trends in shallow water transducers for AUV and UUV missions. Keywords: piezocomposite, broadband, cymbals, transducer , projector

  7. Urban flood modeling using shallow water equations with depth-dependent anisotropic porosity

    NASA Astrophysics Data System (ADS)

    Özgen, Ilhan; Zhao, Jiaheng; Liang, Dongfang; Hinkelmann, Reinhard

    2016-10-01

    The shallow water model with anisotropic porosity conceptually takes into account the unresolved subgrid-scale features, e.g. microtopography or buildings. This enables computationally efficient simulations that can be run on coarser grids, whereas reasonable accuracy is maintained via the introduction of porosity. This article presents a novel numerical model for the depth-averaged equations with anisotropic porosity. The porosity is calculated using the probability mass function of the subgrid-scale features in each cell and updated in each time step. The model is tested in a one-dimensional theoretical benchmark before being evaluated against measurements and high-resolution predictions in three case studies: a dam-break over a triangular bottom sill, a dam-break through an idealized city and a rainfall-runoff event in an idealized urban catchment. The physical processes could be approximated relatively well with the anisotropic porosity shallow water model. The computational resolution influences the porosities calculated at the cell edges and therefore has a large influence on the quality of the solution. The computational time decreased significantly, on average three orders of magnitude, in comparison to the classical high-resolution shallow water model simulation.

  8. Exact solutions of one-dimensional nonlinear shallow water equations over even and sloping bottoms

    NASA Astrophysics Data System (ADS)

    Chirkunov, Yu. A.; Dobrokhotov, S. Yu.; Medvedev, S. B.; Minenkov, D. S.

    2014-03-01

    We establish an equivalence of two systems of equations of one-dimensional shallow water models describing the propagation of surface waves over even and sloping bottoms. For each of these systems, we obtain formulas for the general form of their nondegenerate solutions, which are expressible in terms of solutions of the Darboux equation. The invariant solutions of the Darboux equation that we find are simplest representatives of its essentially different exact solutions (those not related by invertible point transformations). They depend on 21 arbitrary real constants; after "proliferation" formulas derived by methods of group theory analysis are applied, they generate a 27-parameter family of essentially different exact solutions. Subsequently using the derived infinitesimal "proliferation" formulas for the solutions in this family generates a denumerable set of exact solutions, whose linear span constitutes an infinite-dimensional vector space of solutions of the Darboux equation. This vector space of solutions of the Darboux equation and the general formulas for nondegenerate solutions of systems of shallow water equations with even and sloping bottoms give an infinite set of their solutions. The "proliferation" formulas for these systems determine their additional nondegenerate solutions. We also find all degenerate solutions of these systems and thus construct a database of an infinite set of exact solutions of systems of equations of the one-dimensional nonlinear shallow water model with even and sloping bottoms.

  9. Pressure gradient sensors for bearing determination in shallow water tracking ranges

    NASA Astrophysics Data System (ADS)

    Stein, Peter J.; Euerle, Steven E.; Menoche, Richard K.; Janiesch, Robert E.

    1996-04-01

    Underwater acoustic tracking has traditionally used only the arrival time of tracking pings to localize targets. This implies that the ping transmitted from a target must be received at a minimum of three separate nodes (receiver locations) in order to determine the position. For deep water ranges this was acceptable. In shallow water, where propagation ranges are limited, this requires a large number of nodes. This makes shallow water ranges very costly. An effort is underway to use pressure gradient hydrophones as receivers and measure the bearing of the ping arrival along with arrival time, thereby locating the target using only one tracking node. This allows for increased node spacing and greatly reduced cost. However, the accuracy required for training ranges is on the order of 1 degree. Further, the directional receiver must be housed so as to withstand impacts from fishing operations. Research including design, fabrication, and testing of conventional and unconventional pressure gradient hydrophones, the housing, and signal processing methods are discussed. Extensive testing has already been conducted using a 1″ diameter by 5″ long multimode hydrophone. A shallow water tracking test was conducted at the NUWC Lake Seneca test facility. The results demonstrate the feasibility of tracking using a single pressure gradient hydrophone with an accuracy of 50 yds out to 2 kyds. The effects of multiple paths and scattering are also discussed.

  10. Microbial diversity in shallow-water hydrothermal sediments of Kueishan Island, Taiwan as revealed by pyrosequencing.

    PubMed

    Wang, Li; Cheung, Man Kit; Kwan, Hoi Shan; Hwang, Jiang-Shiou; Wong, Chong Kim

    2015-11-01

    Kueishan Island is a young volcanic island in the southernmost edge of the Okinawa Trough in the northeastern part of Taiwan. A cluster of hydrothermal vents is located off the southeastern tip of the Island at water depths between 10 and 80 m. This paper presents the results of the first study on the microbial communities in bottom sediments collected from the shallow-water hydrothermal vents of Kueishan Island. Small-subunit ribosomal RNA gene-based high-throughput 454 pyrosequencing was used to characterize the assemblages of bacteria, archaea, and small eukaryotes in sediment samples collected at various distances from the hydrothermal vents. Sediment from the vent area contained the highest diversity of archaea and the lowest diversity of bacteria and small eukaryotes. Epsilonproteobacteria were the most abundant group in the vent sediment, but their abundance decreased with increasing distance from the vent area. Most Epsilonproteobacteria belonged to the mesophilic chemolithoautotrophic genera Sulfurovum and Sulfurimonas. Recent reports on these two genera have come from deep-sea hydrothermal vents. Conversely, the relative contribution of Gammaproteobacteria to the bacterial community increased with increasing distance from the vent area. Our study revealed the contrasting effects of venting on the benthic bacterial and archaeal communities, and showed that the sediments of the shallow-waters hydrothermal vents were dominated by chemoautotrophic bacteria. The present work broadens our knowledge on microbial diversity in shallow-water hydrothermal vent habitats.

  11. On Classical Solutions to 2D Shallow Water Equations with Degenerate Viscosities

    NASA Astrophysics Data System (ADS)

    Li, Yachun; Pan, Ronghua; Zhu, Shengguo

    2017-03-01

    2D shallow water equations have degenerate viscosities proportional to surface height, which vanishes in many physical considerations, say, when the initial total mass, or energy are finite. Such a degeneracy is a highly challenging obstacle for development of well-posedness theory, even local-in-time theory remains open for a long time. In this paper, we will address this open problem with some new perspectives, independent of the celebrated BD-entropy (Bresch et al in Commun Math Phys 238:211-223, 2003, Commun Part Differ Eqs 28:843-868, 2003, Analysis and Simulation of Fluid Dynamics, 2007). After exploring some interesting structures of most models of 2D shallow water equations, we introduced a proper notion of solution class, called regular solutions, and identified a class of initial data with finite total mass and energy, and established the local-in-time well-posedness of this class of smooth solutions. The theory is applicable to most relatively physical shallow water models, broader than those with BD-entropy structures. We remark that our theory is on the local strong solutions, while the BD entropy is an essential tool for the global weak solutions. Later, a Beale-Kato-Majda type blow-up criterion is also established. This paper is mainly based on our early preprint (Li et al. in 2D compressible Navier-Stokes equations with degenerate viscosities and far field vacuum, preprint. arXiv:1407.8471, 2014).

  12. A high-order element-based Galerkin Method for the global shallow water equations.

    SciTech Connect

    Nair, Ramachandran D.; Tufo, Henry M.; Levy, Michael Nathan

    2010-08-01

    The shallow water equations are used as a test for many atmospheric models because the solution mimics the horizontal aspects of atmospheric dynamics while the simplicity of the equations make them useful for numerical experiments. This study describes a high-order element-based Galerkin method for the global shallow water equations using absolute vorticity, divergence, and fluid depth (atmospheric thickness) as the prognostic variables, while the wind field is a diagnostic variable that can be calculated from the stream function and velocity potential (the Laplacians of which are the vorticity and divergence, respectively). The numerical method employed to solve the shallow water system is based on the discontinuous Galerkin and spectral element methods. The discontinuous Galerkin method, which is inherently conservative, is used to solve the equations governing two conservative variables - absolute vorticity and atmospheric thickness (mass). The spectral element method is used to solve the divergence equation and the Poisson equations for the velocity potential and the stream function. Time integration is done with an explicit strong stability-preserving second-order Runge-Kutta scheme and the wind field is updated directly from the vorticity and divergence at each stage, and the computational domain is the cubed sphere. A stable steady-state test is run and convergence results are provided, showing that the method is high-order accurate. Additionally, two tests without analytic solutions are run with comparable results to previous high-resolution runs found in the literature.

  13. Diversity and Distribution of Prokaryotes within a Shallow-Water Pockmark Field

    PubMed Central

    Giovannelli, Donato; d'Errico, Giuseppe; Fiorentino, Federica; Fattorini, Daniele; Regoli, Francesco; Angeletti, Lorenzo; Bakran-Petricioli, Tatjana; Vetriani, Costantino; Yücel, Mustafa; Taviani, Marco; Manini, Elena

    2016-01-01

    Pockmarks are crater-like depression on the seafloor associated with hydrocarbon ascent through muddy sediments in continental shelves around the world. In this study, we examine the diversity and distribution of benthic microbial communities at shallow-water pockmarks adjacent to the Middle Adriatic Ridge. We integrate microbial diversity data with characterization of local hydrocarbons concentrations and sediment geochemistry. Our results suggest these pockmarks are enriched in sedimentary hydrocarbons, and host a microbial community dominated by Bacteria, even in deeper sediment layers. Pockmark sediments showed higher prokaryotic abundance and biomass than surrounding sediments, potentially due to the increased availability of organic matter and higher concentrations of hydrocarbons linked to pockmark activity. Prokaryotic diversity analyses showed that the microbial communities of these shallow-water pockmarks are unique, and comprised phylotypes associated with the cycling of sulfur and nitrate compounds, as well as numerous know hydrocarbon degraders. Altogether, this study suggests that shallow-water pockmark habitats enhance the diversity of the benthic prokaryotic biosphere by providing specialized environmental niches. PMID:27379070

  14. Biding their time - Insights from propagule experiments into the assemblage composition of shallow-water foraminifera under environmental change

    NASA Astrophysics Data System (ADS)

    Weinmann, Anna E.; Goldstein, Susan T.

    2016-04-01

    The assemblage composition of shallow-water foraminifera in coastal environments is often strongly influenced by water temperature and salinity. Community structures of foraminifera have long been used as indicators for environmental change. This is - at least partly - due to their ability to respond quickly to changing local conditions, which becomes increasingly important in the wake of ongoing climate change. In this study, we examined the range of assemblage compositions that grow and develop under different combinations of temperature and salinity. We did this by applying the Propagule Method using several coastal sites in Georgia and Florida (United States). The Propagule Method is an experimental tool for examining the growth of foraminiferal assemblages from suites of tiny juveniles that occur in the "propagule banks" found within the fine fraction of the sediment. We exposed the propagule banks from our study sites to different temperatures (18, 24, and 30°C) and salinities (15 and 35) over a period of 5 weeks, to simulate different shallow-water conditions. Results show that foraminifera grew abundantly in all experimental treatments, with increased growth and reproduction occurring at higher temperatures (24 and 30°C). Salinity had a strong influence on the species composition of the experimental assemblages. The most successful species were opportunists and known "pioneer" species such as Ammonia tepida (Cushman) or Quinqueloculina seminula (Linné). However, we also found significant numbers of allochthonous or "exotic" species that occurred only in rare numbers or were even absent from the living in situ assemblages of the study sites. The presence of allochthonous taxa resulted from propagule recruitment from areas beyond our immediate study sites. These propagules - which might be transported even beyond their ecological range - may remain viable within the propagule bank until environmental conditions become favorable. As such, they are "biding

  15. Shallow-water carbonate records of hyperthermals: do Pacific Ocean guyots hold the key? (Invited)

    NASA Astrophysics Data System (ADS)

    Robinson, S. A.

    2010-12-01

    The Paleocene-Eocene Thermal Maximum (PETM; ~55.8 Ma) is associated with a rapid and large carbon cycle perturbation, transient warming and deep-sea acidification, and is the best-known example of a hyperthermal event. Although this event is widely known from pelagic, hemipelagic and continental records, the lack of in situ, shallow-water, carbonate-platform sections inhibits interpretations of whether the PETM had a significant effect on shallow-water carbonate ecosystems. Guyots in the Pacific Ocean are submerged seamounts that comprise a volcanic pedestal, topped with shallow-water carbonates (that accumulated at or close to sea-level) and a pelagic cap that formed after the platform ‘drowned’ (sunk below the photic zone). The isolated carbonate platforms on these guyots formed far from terrigenous input and runoff, both detrimental effects for calcifying organisms. The isolation and thickness of the carbonate platforms on guyots makes them ideal localities at which to investigate the response of shallow-water carbonate ecosystems to changes in surface ocean temperature and chemistry, free from the complications that can affect continental margin settings. Limalok Guyot (ODP Site 871) in the Pacific Ocean comprises a volcanic pedestal topped by a Paleogene carbonate platform that drowned in the middle Eocene. Carbon-isotope stratigraphy of the platform carbonate sediments will be presented, in conjunction with existing biostratigraphy, to refine the stratigraphic framework of the carbonate platform. Although core recovery was poor, the major Late Paleocene-Middle Eocene stratigraphic trends in carbon-isotopes can be recognized, including a prominent ~3‰ negative carbon isotope excursion (CIE), recording the onset of the PETM. The lithological and paleontological record of the PETM on Limalok Guyot shows no major evidence for a carbonate production crisis, suggesting that the effects of any changes in temperatures or surface ocean pH were relatively short

  16. Bone-Eating Worms Spread: Insights into Shallow-Water Osedax (Annelida, Siboglinidae) from Antarctic, Subantarctic, and Mediterranean Waters

    PubMed Central

    Taboada, Sergi; Riesgo, Ana; Bas, Maria; Arnedo, Miquel A.; Cristobo, Javier; Rouse, Greg W.; Avila, Conxita

    2015-01-01

    Osedax, commonly known as bone-eating worms, are unusual marine annelids belonging to Siboglinidae and represent a remarkable example of evolutionary adaptation to a specialized habitat, namely sunken vertebrate bones. Usually, females of these animals live anchored inside bone owing to a ramified root system from an ovisac, and obtain nutrition via symbiosis with Oceanospirillales gamma-proteobacteria. Since their discovery, 26 Osedax operational taxonomic units (OTUs) have been reported from a wide bathymetric range in the Pacific, the North Atlantic, and the Southern Ocean. Using experimentally deployed and naturally occurring bones we report here the presence of Osedax deceptionensis at very shallow-waters in Deception Island (type locality; Antarctica) and at moderate depths near South Georgia Island (Subantarctic). We present molecular evidence in a new phylogenetic analysis based on five concatenated genes (28S rDNA, Histone H3, 18S rDNA, 16S rDNA, and cytochrome c oxidase I–COI–), using Maximum Likelihood and Bayesian inference, supporting the placement of O. deceptionensis as a separate lineage (Clade VI) although its position still remains uncertain. This phylogenetic analysis includes a new unnamed species (O. ‘mediterranea’) recently discovered in the shallow-water Mediterranean Sea belonging to Osedax Clade I. A timeframe of the diversification of Osedax inferred using a Bayesian framework further suggests that Osedax diverged from other siboglinids during the Middle Cretaceous (ca. 108 Ma) and also indicates that the most recent common ancestor of Osedax extant lineages dates to the Late Cretaceous (ca. 74.8 Ma) concomitantly with large marine reptiles and teleost fishes. We also provide a phylogenetic framework that assigns newly-sequenced Osedax endosymbionts of O. deceptionensis and O. ‘mediterranea’ to ribospecies Rs1. Molecular analysis for O. deceptionensis also includes a COI-based haplotype network indicating that individuals from

  17. Bone-Eating Worms Spread: Insights into Shallow-Water Osedax (Annelida, Siboglinidae) from Antarctic, Subantarctic, and Mediterranean Waters.

    PubMed

    Taboada, Sergi; Riesgo, Ana; Bas, Maria; Arnedo, Miquel A; Cristobo, Javier; Rouse, Greg W; Avila, Conxita

    2015-01-01

    Osedax, commonly known as bone-eating worms, are unusual marine annelids belonging to Siboglinidae and represent a remarkable example of evolutionary adaptation to a specialized habitat, namely sunken vertebrate bones. Usually, females of these animals live anchored inside bone owing to a ramified root system from an ovisac, and obtain nutrition via symbiosis with Oceanospirillales gamma-proteobacteria. Since their discovery, 26 Osedax operational taxonomic units (OTUs) have been reported from a wide bathymetric range in the Pacific, the North Atlantic, and the Southern Ocean. Using experimentally deployed and naturally occurring bones we report here the presence of Osedax deceptionensis at very shallow-waters in Deception Island (type locality; Antarctica) and at moderate depths near South Georgia Island (Subantarctic). We present molecular evidence in a new phylogenetic analysis based on five concatenated genes (28S rDNA, Histone H3, 18S rDNA, 16S rDNA, and cytochrome c oxidase I-COI-), using Maximum Likelihood and Bayesian inference, supporting the placement of O. deceptionensis as a separate lineage (Clade VI) although its position still remains uncertain. This phylogenetic analysis includes a new unnamed species (O. 'mediterranea') recently discovered in the shallow-water Mediterranean Sea belonging to Osedax Clade I. A timeframe of the diversification of Osedax inferred using a Bayesian framework further suggests that Osedax diverged from other siboglinids during the Middle Cretaceous (ca. 108 Ma) and also indicates that the most recent common ancestor of Osedax extant lineages dates to the Late Cretaceous (ca. 74.8 Ma) concomitantly with large marine reptiles and teleost fishes. We also provide a phylogenetic framework that assigns newly-sequenced Osedax endosymbionts of O. deceptionensis and O. 'mediterranea' to ribospecies Rs1. Molecular analysis for O. deceptionensis also includes a COI-based haplotype network indicating that individuals from Deception

  18. Changes in amphipod (Crustacea) assemblages associated with shallow-water algal habitats invaded by Caulerpa racemosa var. cylindracea in the western Mediterranean Sea.

    PubMed

    Vázquez-Luis, M; Sanchez-Jerez, P; Bayle-Sempere, J T

    2008-06-01

    The effects of the invasive species Caulerpa racemosa var. cylindracea (hereafter C. racemosa) on amphipod assemblages associated with shallow-water rocky habitats were studied. Two habitats located along the SE Iberian Peninsula were compared; invaded and non-invaded. The results showed that growth of C. racemosa affects habitat structure, influencing the species composition and biomass of macroalgae, and detritus accumulation. In turn, such changes in habitat features affected the associated amphipod assemblages with different ecological requirements. However, the species richness of amphipods was relatively high in both habitats, while the species composition of amphipods changed completely. For example, some species such as Ampithoe ramondi and Hyale schmidti did not colonize invaded habitats, while others such as Apocorophium acutum were favoured by the spread of C. racemosa. Habitat invasion by C. racemosa can have an important influence on biotic assemblages, modifying both habitat structure and the associated fauna, with unknown effects on the overall ecosystem.

  19. Seaweed fails to prevent ocean acidification impact on foraminifera along a shallow-water CO2 gradient

    PubMed Central

    Pettit, Laura R; Smart, Christopher W; Hart, Malcolm B; Milazzo, Marco; Hall-Spencer, Jason M

    2015-01-01

    Ocean acidification causes biodiversity loss, alters ecosystems, and may impact food security, as shells of small organisms dissolve easily in corrosive waters. There is a suggestion that photosynthetic organisms could mitigate ocean acidification on a local scale, through seagrass protection or seaweed cultivation, as net ecosystem organic production raises the saturation state of calcium carbonate making seawater less corrosive. Here, we used a natural gradient in calcium carbonate saturation, caused by shallow-water CO2 seeps in the Mediterranean Sea, to assess whether seaweed that is resistant to acidification (Padina pavonica) could prevent adverse effects of acidification on epiphytic foraminifera. We found a reduction in the number of species of foraminifera as calcium carbonate saturation state fell and that the assemblage shifted from one dominated by calcareous species at reference sites (pH ∼8.19) to one dominated by agglutinated foraminifera at elevated levels of CO2 (pH ∼7.71). It is expected that ocean acidification will result in changes in foraminiferal assemblage composition and agglutinated forms may become more prevalent. Although Padina did not prevent adverse effects of ocean acidification, high biomass stands of seagrass or seaweed farms might be more successful in protecting epiphytic foraminifera. PMID:26140195

  20. Seaweed fails to prevent ocean acidification impact on foraminifera along a shallow-water CO2 gradient.

    PubMed

    Pettit, Laura R; Smart, Christopher W; Hart, Malcolm B; Milazzo, Marco; Hall-Spencer, Jason M

    2015-05-01

    Ocean acidification causes biodiversity loss, alters ecosystems, and may impact food security, as shells of small organisms dissolve easily in corrosive waters. There is a suggestion that photosynthetic organisms could mitigate ocean acidification on a local scale, through seagrass protection or seaweed cultivation, as net ecosystem organic production raises the saturation state of calcium carbonate making seawater less corrosive. Here, we used a natural gradient in calcium carbonate saturation, caused by shallow-water CO2 seeps in the Mediterranean Sea, to assess whether seaweed that is resistant to acidification (Padina pavonica) could prevent adverse effects of acidification on epiphytic foraminifera. We found a reduction in the number of species of foraminifera as calcium carbonate saturation state fell and that the assemblage shifted from one dominated by calcareous species at reference sites (pH ∼8.19) to one dominated by agglutinated foraminifera at elevated levels of CO2 (pH ∼7.71). It is expected that ocean acidification will result in changes in foraminiferal assemblage composition and agglutinated forms may become more prevalent. Although Padina did not prevent adverse effects of ocean acidification, high biomass stands of seagrass or seaweed farms might be more successful in protecting epiphytic foraminifera.

  1. A new species of Oceanobdella (Hirudinida: Piscicolidae) from the plain sculpin, Myoxocephalus jaok, from Bristol Bay, Alaska.

    PubMed

    Burreson, Eugene M; Williams, Julianne I

    2004-08-01

    Oceanobdella khani n. sp. is described from the plain sculpin, Myoxocephalus jaok, from Bristol Bay, Alaska, in the eastern Bering Sea. Prevalence was never greater than 10% in any single collection; maximum intensity was 12 leeches per host, but most fish had 5 or fewer leeches. Oceanobdella khani possesses generic characters of small oral sucker, 5 pairs of testisacs, unremarkable terminal male reproductive organs, coelomic system lacking pulsatile vesicles, and 3 pairs of eyes on the oral sucker-trachelosome. Oceanobdella khani is distinguished from other species in the genus by solid black pigmentation on the urosome, clitellum, trachelosome, and most of the oral sucker except for an unpigmented margin. The pigmentation of the caudal sucker is highly variable, ranging from overall mottled blackish gray to completely unpigmented. The caudal sucker lacks ocelli. Intestinal ceca are large, crop ceca are directed anteriorly, and postceca are separate for their entire length.

  2. Hexactinellid sponges reported from shallow waters in the Oligo-Miocene Pirabas Formation (N Brazil) are in fact cheilostome bryozoans

    NASA Astrophysics Data System (ADS)

    Muricy, Guilherme; Domingos, Celso; Távora, Vladimir A.; Ramalho, Laís V.; Pisera, Andrzej; Taylor, Paul

    2016-12-01

    Although hexactinellid sponges occur exclusively in deep and/or cold waters, three species of hexactinellids have been reported from shallow and warm waters in Oligo-Miocene deposits of the Pirabas Formation in northern Brazil: Aphrocallistes estevoui, A. lobata and Manzonia aprutina. Here we re-examine these fossils and show that they are not hexactinellid sponges but instead comprise three species of cheilostome bryozoans of the genus Celleporaria (Family Lepraliellidae). Two of these are new to science, viz., Celleporaria pirabasensis sp. nov. and Celleporaria triangulavicularis sp. nov., and the third could not be identified to species level due to poor preservation. Colonies of all three species are massive and multilaminar, with irregular layers of zooids produced by frontal budding. Autozooids have marginal areolar pores and a rounded, asinuate primary orifice. All colonies also have suboral adventitious avicularia and interzooidal avicularia, although of different shapes and sizes. Celleporaria triangulavicularis sp. nov. has distinctive triangular interzooidal avicularia. The underside of the frontal shield was seen only in Celleporaria pirabasensis sp. nov. and Celleporaria sp., in which it is umbonuloid. Ovicells were only seen in Celleporaria pirabasensis sp. nov. and are cap-shaped. The three species differ among themselves mainly in the shape and position of the adventitious and interzooidal avicularia. The presence of several typical bryozoan traits and the absence of spicule traces or any other sponge features clearly demonstrate that these fossils are bryozoans, not sponges. The change in the classification of these fossils from hexactinellids to bryozoans of the genus Celleporaria eliminates the incongruence of the occurrence of deep-water species in the warm shallow water depositional environment of the Pirabas Formation.

  3. Response of shallow-water carbonates and reef systems to the Toarcian Ocean Anoxic Event (183 Ma) on the Dinaric Carbonate Platform (Slovenia)

    NASA Astrophysics Data System (ADS)

    Martindale, R. C.; Kosir, A.; Schaller, M. F.

    2015-12-01

    With rising concerns regarding the persistence of coral reefs through the 21st century, there is a crucial need to understand how these ecosystems will respond to future environmental deterioration (e.g. ocean warming, acidification, and decreased oxygenation). Several ancient events have been identified as good analogues for modern ecological changes, however, most of these correspond to mass extinction events. By studying carbon cycle perturbations that caused more minor ecosystem collapse, such as the Toarcian Ocean Anoxic Event (T-OAE), the key physiological, ecological, and environmental features that correlate with species and community survival can be assessed. The Dinaric Carbonate Platform, which extends from northeastern Italy to northwestern Albania, is one of the few platforms in Europe that captures an almost continuous shallow-water record of Pliensbachian and Toarcian strata. Specifically, this comparatively poorly studied platform captures the T-OAE in shallow-water carbonates. One such outcrop on the Trnovski Gozd karst plateau in western Slovenia contains both Pleinsbachian lithiotid (bivalve) biostromes and coral bioherms (i.e. coral reefs). The occurrence of both lithiotid and coral buildups in one section is extremely rare and provides the opportunity to study the response of both communities, as well as the carbonate system as a whole, to the T-OAE. This research focuses on the lithology and chemostratigraphy from this locality, particularly identifying the T-OAE horizon more precisely. Additionally, (micro)facies analyses and paleontological analyses of the reefs themselves will be presented. These data will establish the paleoenvironmental conditions that favored reef growth in the Pliensbachian, as well as what conditions changed at the stage boundary and T-OAE to cause the collapse of the shallow-water carbonates and reef systems.

  4. A method for measuring vertical accretion, elevation, and compaction of soft, shallow-water sediments

    USGS Publications Warehouse

    Cahoon, D.R.; Marin, P.E.; Black, B.K.; Lynch, J.C.

    2000-01-01

    High-resolution measures of vertical accretion, elevation, and compaction of shallow-water sediments are fundamental to understanding the processes that control elevation change and the mechanisms of progradation (e.g., development of mudflats and intertidal wetlands) in coastal systems. Yet, measurements of elevation by traditional survey methods often are of low accuracy because of the compressible nature of the substrates. Nor do they provide measures of vertical accretion or sediment compaction. This paper evaluates the use in shallow-water systems of an approach designed to measure these variables in vegetated wetlands. The approach employs simultaneous measures of elevation from temporary benchmarks using a sedimentation-erosion table (SET) and vertical accretion from marker horizons with sediment cores collected with a cryogenic coring apparatus. The measures are made with a level of resolution sufficient to distinguish between the influence of surface and subsurface processes on elevation, thus providing quantitative estimates of shallow subsidence. The SET-marker horizon approach was evaluated on a developing splay created by an artificial crevasse of a distributary in the Mississippi River delta. The approach provided high-resolution measures of vertical accretion (48.3 ' 2.0 cm.) and elevation (36.7 ' 1.6 cm) over a 4-year period, with the difference between the two indicating the amount of shallow subsidence. In addition, by laying new marker horizons in later years, the approach provided rates not only of shallow subsidence (3.9 ' 0.5 cm y-1) but also compaction of newly deposited seiments (2.1 ' 0.6 cm y-1) and compaction of underlying sediments (1.8 ' 2.0 cm y-1 ) over a two-year period. Hence, the SET-marker horizon approach has widespread applicability in both emergent wetland and shallow water environments for providing high resolution measures of the processes controlling elevation change.

  5. Hyperspectral remote sensing protocol development for submerged aquatic vegetation in shallow waters

    NASA Astrophysics Data System (ADS)

    Bostater, Charles R., Jr.; Ghir, Teddy; Bassetti, Luce; Hall, Carlton; Reyeier, E.; Lowers, R.; Holloway-Adkins, K.; Virnstein, Robert

    2004-02-01

    Submerged aquatic vegetation (SAV) is an important indicator of freshwater and marine water quality in almost all shallow water aquatic environments. Throughout the world the diversity of submerged aquatic vegetation appears to be in decline, although sufficient historical data, of sufficient quantitative quality is lacking. Hyperspectral remote sensing technology, available from low altitude aircraft sensors, may provide a basis to improve upon existing photographic regional assessments and monitoring concerned with the aerial extent and coverage of SAV. In addition, modern low altitude remote sensing may also help in the development of environmental satellite requirements for future satellite payloads. This paper documents several important spectral reflectance signature features which may be useful in developing a protocol for remote sensing of SAV, and which is transferable to other shallow water aquatic habitats around the world. Specifically, we show that the shape or curvature of the spectral reflectance absorption feature centered near the chlorophyll absorption region of ~ 675 nm is strongly influenced not only by the relative backscatter region between 530-560 nm, but by a "submerged vegetation red edge" that appears in the 695 to 700 nm region in extremely high density vegetative areas in very shallow waters (= 0.5m depth). This "aquatic biomass red edge" is also observable in deeper waters where there is a shallow subsurface algal boom as demonstrated in this paper. Use of this submerged aquatic red edge feature will become an important component of SAV remote sensing in shallow aquatic habitats, as well as in phytoplankton-related water quality remote sensing applications of surface phytoplankton blooms.

  6. Modeling wind waves from deep to shallow waters in Lake Michigan using unstructured SWAN

    NASA Astrophysics Data System (ADS)

    Mao, Miaohua; van der Westhuysen, André J.; Xia, Meng; Schwab, David J.; Chawla, Arun

    2016-06-01

    Accurate wind-wave simulations are vital for evaluating the impact of waves on coastal dynamics, especially when wave observations are sparse. It has been demonstrated that structured-grid models have the ability to capture the wave dynamics of large-scale offshore domains, and the recent emergence of unstructured meshes provides an opportunity to better simulate shallow-water waves by resolving the complex geometry along islands and coastlines. For this study, wind waves in Lake Michigan were simulated using the unstructured-grid version of Simulating Waves Nearshore (un-SWAN) model with various types of wind forcing, and the model was calibrated using in situ wave observations. Sensitivity experiments were conducted to investigate the key factors that impact wave growth and dissipation processes. In particular, we considered (1) three wind field sources, (2) three formulations for wind input and whitecapping, (3) alternative formulations and coefficients for depth-induced breaking, and (4) various mesh types. We find that un-SWAN driven by Global Environmental Multiscale (GEM) wind data reproduces significant wave heights reasonably well using previously proposed formulations for wind input, recalibrated whitecapping parameters, and alternative formulations for depth-induced breaking. The results indicate that using GEM wind field data as input captures large waves in the midlake most accurately, while using the Natural Neighbor Method wind field reproduces shallow-water waves more accurately. Wind input affects the simulated wave evolution across the whole lake, whereas whitecapping primarily affects wave dynamics in deep water. In shallow water, the process of depth-induced breaking is dominant and highly dependent upon breaker indices and mesh types.

  7. A non-hydrostatic pressure distribution solver for the nonlinear shallow water equations over irregular topography

    NASA Astrophysics Data System (ADS)

    Aricò, Costanza; Lo Re, Carlo

    2016-12-01

    We extend a recently proposed 2D depth-integrated Finite Volume solver for the nonlinear shallow water equations with non-hydrostatic pressure distribution. The proposed model is aimed at simulating both nonlinear and dispersive shallow water processes. We split the total pressure into its hydrostatic and dynamic components and solve a hydrostatic problem and a non-hydrostatic problem sequentially, in the framework of a fractional time step procedure. The dispersive properties are achieved by incorporating the non-hydrostatic pressure component in the governing equations. The governing equations are the depth-integrated continuity equation and the depth-integrated momentum equations along the x, y and z directions. Unlike the previous non-hydrostatic shallow water solver, in the z momentum equation, we retain both the vertical local and convective acceleration terms. In the former solver, we keep only the local vertical acceleration term. In this paper, we investigate the effects of these convective terms and the possible improvements of the computed solution when these terms are not neglected in the governing equations, especially in strongly nonlinear processes. The presence of the convective terms in the vertical momentum equation leads to a numerical solution procedure, which is quite different from the one of the previous solver, in both the hydrostatic and dynamic steps. We discretize the spatial domain using unstructured triangular meshes satisfying the Generalized Delaunay property. The numerical solver is shock capturing and easily addresses wetting/drying problems, without any additional equation to solve at wet/dry interfaces. We present several numerical applications for challenging flooding processes encountered in practical aspects over irregular topography, including a new set of experiments carried out at the Hydraulics Laboratory of the University of Palermo.

  8. Energy conserving and potential-enstrophy dissipating schemes for the shallow water equations

    NASA Technical Reports Server (NTRS)

    Arakawa, Akio; Hsu, Yueh-Jiuan G.

    1990-01-01

    To incorporate potential enstrophy dissipation into discrete shallow water equations with no or arbitrarily small energy dissipation, a family of finite-difference schemes have been derived with which potential enstrophy is guaranteed to decrease while energy is conserved (when the mass flux is nondivergent and time is continuous). Among this family of schemes, there is a member that minimizes the spurious impact of infinite potential vorticities associated with infinitesimal fluid depth. The scheme is, therefore, useful for problems in which the free surface may intersect with the lower boundary.

  9. Documentation of the Goddard Laboratory for atmospheres fourth-order two-layer shallow water model

    NASA Technical Reports Server (NTRS)

    Takacs, L. L. (Compiler)

    1986-01-01

    The theory and numerical treatment used in the 2-level GLA fourth-order shallow water model are described. This model was designed to emulate the horizontal finite differences used by the GLA Fourth-Order General Circulation Model (Kalnay et al., 1983) in addition to its grid structure, form of high-latitude and global filtering, and time-integration schemes. A user's guide is also provided instructing the user on how to create initial conditions, execute the model, and post-process the data history.

  10. Comparison of horizontal difference schemes for the shallow water equations on a sphere

    NASA Technical Reports Server (NTRS)

    Russell, Gary L.; Takano, Kenji; Abramopoulos, Frank

    1987-01-01

    The accuracy of horizontal difference schemes used in the hydrodynamics parts of General Circulation Models are compared by means of numerical experiments for the shallow water equations on a sphere. As expected, the phase lag of moving waves decreases as the order of accuracy of a scheme increases or as the grid resolution increases. Overall, Takano and Wurtele's partial fourth order energy and potential enstrophy conserving scheme on the C grid is most accurate. It is clearly superior to the other schemes for the Rossby-Haurwitz wave number 6 initial conditions for coarse grid resolution.

  11. Mid-frequency acoustic propagation in shallow water on the New Jersey shelf: mean intensity.

    PubMed

    Tang, Dajun; Henyey, Frank S; Wang, Zhongkang; Williams, Kevin L; Rouseff, Daniel; Dahl, Peter H; Quijano, Jorge; Choi, Jee Woong

    2008-09-01

    Mid-frequency (1-10 kHz) sound propagation was measured at ranges 1-9 km in shallow water in order to investigate intensity statistics. Warm water near the bottom results in a sound speed minimum. Environmental measurements include sediment sound speed and water sound speed and density from a towed conductivity-temperature-depth chain. Ambient internal waves contribute to acoustic fluctuations. A simple model involving modes with random phases predicts the mean transmission loss to within a few dB. Quantitative ray theory fails due to near axial focusing. Fluctuations of the intensity field are dominated by water column variability.

  12. Preliminary Computational Fluid Dynamics (CFD) Simulation of EIIB Push Barge in Shallow Water

    NASA Astrophysics Data System (ADS)

    Beneš, Petr; Kollárik, Róbert

    2011-12-01

    This study presents preliminary CFD simulation of EIIb push barge in inland conditions using CFD software Ansys Fluent. The RANSE (Reynolds Averaged Navier-Stokes Equation) methods are used for the viscosity solution of turbulent flow around the ship hull. Different RANSE methods are used for the comparison of their results in ship resistance calculations, for selecting the appropriate and removing inappropriate methods. This study further familiarizes on the creation of geometrical model which considers exact water depth to vessel draft ratio in shallow water conditions, grid generation, setting mathematical model in Fluent and evaluation of the simulations results.

  13. Using Hough harmonics to validate and assess nonlinear shallow-water models

    NASA Technical Reports Server (NTRS)

    Dee, Dick P.; Moraes Da Silva, Arlindo

    1986-01-01

    The implementation of a technique for locating programming errors in shallow-water codes, establishing the correctness of the code, and assessing the performance of the numerical model under various flow conditions is described. The right-hand side of the differential equations is modified in such a way that the exact solution of the nonlinear initial-value problem is known, so that the truncation errors of the numerical scheme can be studied in detail. The exact solution is prescribed to be any linear combination of Hough harmonics which propagate in time according to their natural frequencies.

  14. Symmetry analysis of a system of modified shallow-water equations

    NASA Astrophysics Data System (ADS)

    Szatmari, Simon; Bihlo, Alexander

    2014-03-01

    We revise the symmetry analysis of a modified system of one-dimensional shallow-water equations (MSWE) recently considered by Raja Sekhar and Sharma [Commun Nonlinear Sci Numer Simulat 2012;20:630-36]. Only a finite dimensional subalgebra of the maximal Lie invariance algebra of the MSWE, which in fact is infinite dimensional, was found in the aforementioned paper. The MSWE can be linearized using a hodograph transformation. An optimal list of inequivalent one-dimensional subalgebras of the maximal Lie invariance algebra is constructed and used for Lie reductions. Non-Lie solutions are found from solutions of the linearized MSWE.

  15. Unique laminar-flow stability limit based shallow-water theory

    USGS Publications Warehouse

    Chen, Cheng-lung

    1993-01-01

    Two approaches are generally taken in deriving the stability limit for the Froude member (Fs) for laminar sheet flow. The first approach used the Orr-Sommerfeld equation, while the second uses the cross-section-averaged equations of continuity and motion. Because both approaches are based on shallow-water theory, the values of Fs obtained from both approaches should be identical, yet in the literature they are not. This suggests that a defect exists in at least one of the two approaches. After examining the governing equations used in both approaches, one finds that the existing cross-section -averaged equation of motion is dependent on the frame of reference.

  16. Brucella species survey in polar bears (ursus maritimus) of northern Alaska.

    PubMed

    O'Hara, Todd M; Holcomb, Darce; Elzer, Philip; Estepp, Jessica; Perry, Quinesha; Hagius, Sue; Kirk, Cassandra

    2010-07-01

    We report on the presence of specific antibodies to Brucella spp. and Yersinia enterocolitica in polar bears (Ursus maritimus) from northern Alaska (southern Beaufort Sea) during 2003-2006. Based on numerous known stressors (e.g., climate change and loss of sea ice habitat, contaminants), there is increased concern regarding the status of polar bears. Considering these changes, it is important to assess exposure to potentially pathogenic organisms and to improve understanding of transmission pathways. Brucella or specific antibodies to Brucella spp. has been reported in marine mammals. Various assays were used to elucidate the pathway or source of exposure (e.g., "marine" vs. "terrestrial" Brucella spp.) of northern Alaska polar bears to Brucella spp. The standard plate test (SPT) and the buffered Brucella antigen card test (BBA) were used for initial screening for antibodies specific to Brucella. We then evaluated positive reactors (presence of serum antibody specific for Brucella spp.) using immunoblots and competitive enzyme-linked immunosorbent assay (cELISA; based on pinniped-derived Brucella spp. antigen). Annual prevalence of antibody (BBA and SPT) for Brucella spp. ranged from 6.8% to 18.5% over 2003-2006, with an overall prevalence of 10.2%. Prevalence of Brucella spp. antibody did vary by age class. Western blot analyses indicated 17 samples were positive for Brucella spp. antibody; of these, 13 were negative by marine (pinniped) derived Brucella antigen cELISA and four were positive by marine cELISA. Of the four samples positive for Brucella antibody by marine cELISA, three cross-reacted with Y. enterocolitica and Brucella spp. (one sample was Brucella negative and Y. enterocolitica positive). It appears the polar bear antibody does not react with the antigens used on the marine cELISA assay, potentially indicating a terrestrial (nonpinniped) source of Brucella spp.

  17. Species and size selectivity of two midwater trawls used in an acoustic survey of the Alaska Arctic

    NASA Astrophysics Data System (ADS)

    De Robertis, Alex; Taylor, Kevin; Williams, Kresimir; Wilson, Christopher D.

    2017-01-01

    Acoustic-trawl (AT) survey methods are widely used to estimate the abundance and distribution of pelagic organisms. This technique relies on estimates of size and species composition from trawl catches along with estimates of the acoustic properties of these animals to convert measurements of acoustic backscatter into animal abundance. However, trawls are selective samplers, and if the catch does not represent the size and species composition of the animals in the acoustic beam the resulting abundance estimates will be biased. We conducted an experiment to quantify trawl selectivity for species encountered during an AT survey of the Alaska Arctic. The pelagic assemblage in this environment was dominated by small young-of-the-year (age-0) fishes and jellyfish, which may be poorly retained in trawls. A large midwater trawl (Cantrawl) and a smaller midwater trawl (modified Marinovich) were used during the survey. The Marinovich was equipped with 8 small-mesh recapture nets which were used to estimate the probability that an individual that enters the trawl is retained. In addition, paired hauls were made with the Cantrawl and Marinovich to estimate the difference in selectivity between the two trawls. A statistical model was developed to combine the catches of the recapture nets and the paired hauls to estimate the length-dependent selectivity of the trawls for the most abundant species (e.g., age-0 fishes and jellyfish). The analysis indicated that there was substantial size and species selectivity: although the modified Marinovich generally had a higher catch per unit effort, many of the animals encountered in this environment were poorly retained by both trawls. The observed size and species selectivity of the trawls can be used to select appropriate nets for sampling pelagic fishes, and correct survey estimates for the biases introduced in the trawl capture process.

  18. Limited effects of a keystone species: Trends of sea otters and kelp forests at the Semichi Islands, Alaska

    USGS Publications Warehouse

    Konar, B.

    2000-01-01

    Sea otters are well known as a keystone species because of their ability to transform sea urchin-dominated communities into kelp-dominated communities by preying on sea urchins and thus reducing the intensity of herbivory. After being locally extinct for more than a century, sea otters re-colonized the Semichi Islands in the Aleutian Archipelago, Alaska in the early 1990s. Here, otter populations increased to about 400 individuals by 1994, but rapidly declined to about 100 by 1997. Roughly 7 yr after initial otter re-colonization, there were only marginal changes in sea urchin biomass, mean maximum test size, and kelp density. These small changes may be the first steps in the cascading effects on community structure typically found with the invasion of a keystone species. However, no wholesale change in community structure occurred following re-colonization and growth of the sea otter population. Instead, this study describes a transition state and identifies factors such as keystone species density and residence time that can be important in dictating the degree to which otter effects are manifested.

  19. Parallel iterative solution for h and p approximations of the shallow water equations

    USGS Publications Warehouse

    Barragy, E.J.; Walters, R.A.

    1998-01-01

    A p finite element scheme and parallel iterative solver are introduced for a modified form of the shallow water equations. The governing equations are the three-dimensional shallow water equations. After a harmonic decomposition in time and rearrangement, the resulting equations are a complex Helmholz problem for surface elevation, and a complex momentum equation for the horizontal velocity. Both equations are nonlinear and the resulting system is solved using the Picard iteration combined with a preconditioned biconjugate gradient (PBCG) method for the linearized subproblems. A subdomain-based parallel preconditioner is developed which uses incomplete LU factorization with thresholding (ILUT) methods within subdomains, overlapping ILUT factorizations for subdomain boundaries and under-relaxed iteration for the resulting block system. The method builds on techniques successfully applied to linear elements by introducing ordering and condensation techniques to handle uniform p refinement. The combined methods show good performance for a range of p (element order), h (element size), and N (number of processors). Performance and scalability results are presented for a field scale problem where up to 512 processors are used. ?? 1998 Elsevier Science Ltd. All rights reserved.

  20. Assessment of Shallow-Water Habitat Availability in Modified Dike Structures, Lower Missouri River, 2004

    USGS Publications Warehouse

    Jacobson, Robert B.; Elliott, Caroline M.; Johnson, Harold E.

    2004-01-01

    This study documented the effects of wing-dike notching on the availabilit of shallow water habitat in the Lower Missouri River. Five wing dikes were surveyed in late May 2004 after they were notched in early May as part of shallow-water habitat (SWH) rehabilitation activities undertaken by the U.S. Army Corps of Engineers. Surveys included high-resolution hydroacoustic depth, velocity, and substrate mapping. Relations of bottom elevations within the wing dike fields to index discharges and water-surface elevations indicate that little habitat meeting the SWH definition was created immediately following notching. This result is not unexpected, as significant geomorphic adjustment may require large flow events. Depth, velocity, and substrate measurements in the post-rehabilitation time period provide baseline data for monitoring ongoing changes. Differences in elevation and substrate were noted at all sites. Most dike fields showed substantial aggradation and replacement of mud substrate with sandier sediment, although the changes did not result in increased availability of SWH at the index discharge. It is not known how much of the elevation and substrate changes can be attributed directly to notching and how much would result from normal sediment transport variation.

  1. Simulation of arrested salt wedges with a multi-layer Shallow Water Lattice Boltzmann model

    NASA Astrophysics Data System (ADS)

    Prestininzi, P.; Montessori, A.; La Rocca, M.; Sciortino, G.

    2016-10-01

    The ability to accurately and efficiently model the intrusion of salt wedges into river beds is crucial to assay its interaction with human activities and the natural environment. We present a 2D multi-layer Shallow Water Lattice Boltzmann (SWLB) model able to predict the salt wedge intrusion in river estuaries. The formulation usually employed for the simulation of gravity currents is here equipped with proper boundary conditions to handle both the downstream seaside outlet and the upstream river inlet. Firstly, the model is validated against highly accurate semi-analytical solutions of the steady state 1D two-layer Shallow Water model. Secondly, the model is applied to a more complex, fully 3D geometry, to assess its capability to handle realistic cases. The simple formulation proposed for the shear interlayer stress is proven to be consistent with the general 3D viscous solution. In addition to the accuracy, the model inherits the efficiency of the Lattice Boltzmann approach to fluid dynamics problems.

  2. Analysis of spurious oscillation modes for the shallow water and Navier-Stokes equations

    USGS Publications Warehouse

    Walters, R.A.; Carey, G.F.

    1983-01-01

    The origin and nature of spurious oscillation modes that appear in mixed finite element methods are examined. In particular, the shallow water equations are considered and a modal analysis for the one-dimensional problem is developed. From the resulting dispersion relations we find that the spurious modes in elevation are associated with zero frequency and large wave number (wavelengths of the order of the nodal spacing) and consequently are zero-velocity modes. The spurious modal behavior is the result of the finite spatial discretization. By means of an artificial compressibility and limiting argument we are able to resolve the similar problem for the Navier-Stokes equations. The relationship of this simpler analysis to alternative consistency arguments is explained. This modal approach provides an explanation of the phenomenon in question and permits us to deduce the cause of the very complex behavior of spurious modes observed in numerical experiments with the shallow water equations and Navier-Stokes equations. Furthermore, this analysis is not limited to finite element formulations, but is also applicable to finite difference formulations. ?? 1983.

  3. Modeling the effects of linear shallow-water internal waves on horizontal array coherence.

    PubMed

    Rouseff, Daniel; Lunkov, Andrey A

    2015-10-01

    The coherence length of a horizontal array is the maximum separation between two points where coherent processing gives useful gain when a distant source is at broadside. In shallow water, the coherence length is limited by the environmental variability caused by several relevant oceanographic processes. In the present study, a statistical model is developed that quantifies how one oceanographic process, linear internal waves, affects the coherence length. A key input to the ocean sub-model is the vertically integrated energy density of the internal wave field. The acoustic sub-model is based on the adiabatic normal mode approximation and so should be reasonable for frequencies under 1 kHz. Numerical calculations using environmental data from the Shallow Water 2006 Experiment (SW06) show how the coherence length of individual modes varies with consequent effects on array coherence. The coherence length is shown to be a strong function of where the source and array are positioned in the water column. For a bottom-mounted array above a moderately lossy seabed, the model predicts a coherence length that depends only weakly on range, an effect observed in field experiments.

  4. High-order nite volume WENO schemes for the shallow water equations with dry states

    SciTech Connect

    Xing, Yulong; Shu, Chi-wang

    2011-01-01

    The shallow water equations are used to model flows in rivers and coastal areas, and have wide applications in ocean, hydraulic engineering, and atmospheric modeling. These equations have still water steady state solutions in which the flux gradients are balanced by the source term. It is desirable to develop numerical methods which preserve exactly these steady state solutions. Another main difficulty usually arising from the simulation of dam breaks and flood waves flows is the appearance of dry areas where no water is present. If no special attention is paid, standard numerical methods may fail near dry/wet front and produce non-physical negative water height. A high-order accurate finite volume weighted essentially non-oscillatory (WENO) scheme is proposed in this paper to address these difficulties and to provide an efficient and robust method for solving the shallow water equations. A simple, easy-to-implement positivity-preserving limiter is introduced. One- and two-dimensional numerical examples are provided to verify the positivity-preserving property, well-balanced property, high-order accuracy, and good resolution for smooth and discontinuous solutions.

  5. Numerical simulations of dynamic coupling between shallow-water sloshing and horizontal vessel motion with baffles

    NASA Astrophysics Data System (ADS)

    Alemi Ardakani, H.; Turner, M. R.

    2016-06-01

    The coupled motion between shallow water sloshing in a moving vessel with baffles and the vessel dynamics is considered. Here the vessel dynamics is restricted to horizontal motion such as in tuned liquid dampers. It was shown by (Turner et al 2013 Phys. Fluids 25 112102) that partitioning a moving vessel into n separate compartments leads to an interesting dynamical behaviour of the system. Also, under particular input parameter values an internal (n+1)-fold 1:\\cdots :1 resonance can be generated, where the frequency of the sloshing fluid in each compartment is equal, and equal to the frequency of the vessel itself. Here the form of the sloshing eigenmodes at this resonance are derived in the shallow-water limit. Using the Lagrangian formulation of the problem, an efficient numerical algorithm is implemented to solve the fully nonlinear system of equations based on the implicit midpoint rule. This algorithm is simple, fast and maintains the energy partition between the vessel and the fluid over long times. In this work numerical results are presented for dynamical vessel/sloshing motion attached to a nonlinear spring.

  6. Microbial response to limited nutrients in shallow water immediately after the end-Permian mass extinction.

    PubMed

    Jia, C; Huang, J; Kershaw, S; Luo, G; Farabegoli, E; Perri, M C; Chen, L; Bai, X; Xie, S

    2012-01-01

    Previous work indicates that a variety of microbes bloomed in the oceans after the end-Permian faunal mass extinction, but evidence is sporadically documented. Thus, the nature and geographic distribution of such microbes and their associations are unclear, addressed in this study using a series of biomarker groups. On the basis of microbial biomarker records of the 2-methylhopane index, evidence is presented for cyanobacterial blooms in both the western and eastern Tethys Sea and in both shallow and deep waters, after the mass extinction. The enhanced relative abundance of C(28) (expressed by the C(28) /C(29) ratio of) regular steranes suggests a bloom of prasinophyte algae occurred immediately after the end-Permian faunal extinction, comparable with those observed in some other mass extinctions in Phanerozoic. Significantly, cyanobacteria and prasinophyte algae show a synchronized onset of bloom in the shallow water Bulla section, north Italy, inferring for the first time their coupled response to the biotic crisis and the associated environmental conditions. However, in Meishan of Zhejiang Province in south China, the bloom declined earlier than in Bulla. The association of increased 2-methylhopane index with a negative shift in the nitrogen isotope composition infers a scenario of enhanced nitrogen fixation by cyanobacteria immediately after the faunal mass extinction. N(2) fixation by cyanobacteria is here interpreted to have provided prasinophyte algae with ammonium in nutrient-limited shallow waters, and thus caused their associated blooms.

  7. A shallow water model for magnetohydrodynamic flows with turbulent Hartmann layers

    NASA Astrophysics Data System (ADS)

    Pothérat, Alban; Schweitzer, Jean-Philippe

    2011-05-01

    We establish a shallow water model for flows of electrically conducting fluids in homogeneous static magnetic fields that are confined between two parallel planes where turbulent Hartmann layers are present. This is achieved by modelling the wall shear stress in these layers using Prandtl's mixing length model, as did by Alboussière and Lingwood [Phys. Fluids 12(6), 1535 (2000)]. The idea for this new model arose from the failure of previous shallow water models that assumed a laminar Hartmann layer to recover the correct amount of dissipation found in some regimes of the MATUR experiment. This experiment, conducted by Messadek and Moreau [J. Fluid Mech. 456, 137 (2002)], consisted of a thin layer of mercury electrically driven in differential rotation in a transverse magnetic field. Numerical simulations of our new model in the configuration of this experiment allowed us to recover experimental values of both the global angular momentum and the local velocity up to a few percent when the Hartmann layer was in a sufficiently well developed turbulent state. We thus provide an evidence that the unexplained level of dissipation observed in MATUR in these specific regimes was caused by turbulence in the Hartmann layers. A parametric analysis of the flow, made possible by the simplicity of our model, also revealed that turbulent friction in the Hartmann layer prevented quasi-2D turbulence from becoming more intense and limited the size of the large scales.

  8. Travel-time tomography in shallow water: experimental demonstration at an ultrasonic scale.

    PubMed

    Roux, Philippe; Iturbe, Ion; Nicolas, Barbara; Virieux, Jean; Mars, Jérôme I

    2011-09-01

    Acoustic tomography in a shallow ultrasonic waveguide is demonstrated at the laboratory scale between two source-receiver arrays. At a 1/1,000 scale, the waveguide represents a 1.1-km-long, 52-m-deep ocean acoustic channel in the kilohertz frequency range. Two coplanar arrays record the transfer matrix in the time domain of the waveguide between each pair of source-receiver transducers. A time-domain, double-beamforming algorithm is simultaneously performed on the source and receiver arrays that projects the multi-reflected acoustic echoes into an equivalent set of eigenrays, which are characterized by their travel times and their launch and arrival angles. Travel-time differences are measured for each eigenray every 0.1 s when a thermal plume is generated at a given location in the waveguide. Travel-time tomography inversion is then performed using two forward models based either on ray theory or on the diffraction-based sensitivity kernel. The spatially resolved range and depth inversion data confirm the feasibility of acoustic tomography in shallow water. Comparisons are made between inversion results at 1 and 3 MHz with the inversion procedure using ray theory or the finite-frequency approach. The influence of surface fluctuations at the air-water interface is shown and discussed in the framework of shallow-water ocean tomography.

  9. Unknown object localization and identification in shallow water environment at Lake Balaton

    NASA Astrophysics Data System (ADS)

    Kiss, Balint; Bostater, Charles R., Jr.; Vajda, Ferenc; Vajta, Laszlo; Vogel, Miklos

    2004-11-01

    This paper addresses a particular detection problem related to the largest freshwater lake of Central and Western Europe, namely the Lake Balaton. The bed-silt of this shallow water lake (its average depth is 3.3 meters) contains several type of objects: industrial debris, historical vestiges, and in particular, an unknown quantity of unexploded ordnance from the second World War. It is important to localize and classify these objects for precise risk assessment and eventual later removal (not addressed in the paper). The bed-silt of the lake can be characterized as a mud having a light and constantly changing structure. It follows that the shallow water is almost always mixed with the mud. This admixture is constantly maintained by winds and navigating boats, hence the underwater visibility is close to zero during the most part of the year, especially in the depth range close to the bottom. Since the climate makes it possible, the authors propose a special way to explore the bed-silt of the lake, namely the use an autonomous vehicle on the frozen lake. Note that the ice prevents the wind and navigating boats to generate water movement and thus the mud is sedimented. This autonomous vehicle is equipped with a GPS based onboard localization system, with multiple sensor and recording equipment, and with a radio link to its command post. More details about the nature of objects to be detected as well as about the architecture of the detection and localization system are presented in the paper.

  10. Fast and parallel spectral transform algorithms for global shallow water models. Doctoral thesis

    SciTech Connect

    Jakob, R.

    1993-01-01

    The dissertation examines spectral transform algorithms for the solution of the shallow water equations on the sphere and studies their implementation and performance on shared memory vector multiprocessors. Beginning with the standard spectral transform algorithm in vorticity divergence form and its implementation in the Fortran based parallel programming language Force, two modifications are researched. First, the transforms and matrices associated with the meridional derivatives of the associated Legendre functions are replaced by corresponding operations with the spherical harmonic coefficients. Second, based on the fast Fourier transform and the fast multipole method, a lower complexity algorithm is derived that uses fast transformations between Legendre and interior Fourier nodes, fast surface spherical truncation and a fast spherical Helmholz solver. Because the global shallow water equations are similar to the horizontal dynamical component of general circulation models, the results can be applied to spectral transform numerical weather prediction and climate models. In general, the derived algorithms may speed up the solution of time dependent partial differential equations in spherical geometry.

  11. Spectral transform methods for solving the shallow-water equations on the sphere

    SciTech Connect

    Swarztrauber, P.N.

    1996-04-01

    The accuracy of computed solutions to several formulations of the shallow-water equations is compared. The shallow-water equations can be written in a number of different forms that are obtained by (a) combining terms into differential expressions; (b) raising the order of the differential equations, for example, the vorticity-divergence formulation, and (c) transforming both independent and dependent variables. Although the exact solutions to the formulations are identical, the properties of the computed solutions vary depending on the formulation and the method of solution. Nine methods are examined, all of which provide satisfactory accuracy for a steady-state test case. The exact solution corresponds to a steady zonal wind that is tilted relative to the computational spherical coordinate system. The resulting wind passes over the North Pole, providing a test of the `pole problem.` Computational details are presented as well as the accuracy of a 5-day computation in both 32- and 64-bit arithmetic. Stability and accuracy are shown to depend on the polar smoothing induced by resynthesis, which is also the accepted method for eliminating nonlinear aliasing. Eight of the nine methods mimic the exact solution by computing a numerical steady-state solution. 19 refs., 2 figs., 4 tabs.

  12. A central-upwind scheme with artificial viscosity for shallow-water flows in channels

    NASA Astrophysics Data System (ADS)

    Hernandez-Duenas, Gerardo; Beljadid, Abdelaziz

    2016-10-01

    We develop a new high-resolution, non-oscillatory semi-discrete central-upwind scheme with artificial viscosity for shallow-water flows in channels with arbitrary geometry and variable topography. The artificial viscosity, proposed as an alternative to nonlinear limiters, allows us to use high-resolution reconstructions at a low computational cost. The scheme recognizes steady states at rest when a delicate balance between the source terms and flux gradients occurs. This balance in irregular geometries is more complex than that taking place in channels with vertical walls. A suitable technique is applied by properly taking into account the effects induced by the geometry. Incorporating the contributions of the artificial viscosity and an appropriate time step restriction, the scheme preserves the positivity of the water's depth. A description of the proposed scheme, its main properties as well as the proofs of well-balance and the positivity of the scheme are provided. Our numerical experiments confirm stability, well-balance, positivity-preserving properties and high resolution of the proposed method. Comparisons of numerical solutions obtained with the proposed scheme and experimental data are conducted, showing a good agreement. This scheme can be applied to shallow-water flows in channels with complex geometry and variable bed topography.

  13. Initial phenomenon of roll wave of shallow water on inclined channel

    NASA Astrophysics Data System (ADS)

    Arai, M.

    2015-12-01

    1. INTRODUCTION Intermittent surges of debris flows are observed in mountain regions. This type of flow is considered to be characterized by developing roll waves (surges) due to flow instabilities and by a weak sediment concentrations. For a understanding of initial phenomenon and fluctuation of the flow depth, wave equations and understanding characteristics of the solutions are needed. It is presented a wave equation and some solutions of roll waves based on shallow water momentum equation. These results show an improved understanding of the phenomena and wave equation of developing roll wave. 2. WAVE EQUATION AND SOME SOLUTIONS Considering momentam equation of shallow water on inclined channel and using reductive perturbation method, a wave equation which is a kind of KdV-Burgers equation was obtained. For on long wave velocity, some analitical solutions and numerical solutions ware obtained. Relationships of wave equation, it's solutions and phenomenon are discussed. 3. CONCLUSION A wave of minute disturbance on long wave velocity is governed by Burgers equation. For not fixed boundary condition and initial wave condition of not multiple wave number, an initial wave is deformed to a wave which wave number is one. The wave is caused a phase and the phenomena is shifted from Burgers equation to KdV-Burgers equation which has the characteristic of the solitary wave.

  14. Tools to Perform Local Dense 3D Reconstruction of Shallow Water Seabed ‡

    PubMed Central

    Avanthey, Loïca; Beaudoin, Laurent; Gademer, Antoine; Roux, Michel

    2016-01-01

    Tasks such as distinguishing or identifying individual objects of interest require the production of dense local clouds at the scale of these individual objects of interest. Due to the physical and dynamic properties of an underwater environment, the usual dense matching algorithms must be rethought in order to be adaptive. These properties also imply that the scene must be observed at close range. Classic robotized acquisition systems are oversized for local studies in shallow water while the systematic acquisition of data is not guaranteed with divers. We address these two major issues through a multidisciplinary approach. To efficiently acquire on-demand stereoscopic pairs using simple logistics in small areas of shallow water, we devised an agile light-weight dedicated system which is easy to reproduce. To densely match two views in a reliable way, we devised a reconstruction algorithm that automatically accounts for the dynamics, variability and light absorption of the underwater environment. Field experiments in the Mediterranean Sea were used to assess the results. PMID:27196913

  15. Semi-implicit finite difference methods for three-dimensional shallow water flow

    USGS Publications Warehouse

    Casulli, Vincenzo; Cheng, Ralph T.

    1992-01-01

    A semi-implicit finite difference method for the numerical solution of three-dimensional shallow water flows is presented and discussed. The governing equations are the primitive three-dimensional turbulent mean flow equations where the pressure distribution in the vertical has been assumed to be hydrostatic. In the method of solution a minimal degree of implicitness has been adopted in such a fashion that the resulting algorithm is stable and gives a maximal computational efficiency at a minimal computational cost. At each time step the numerical method requires the solution of one large linear system which can be formally decomposed into a set of small three-diagonal systems coupled with one five-diagonal system. All these linear systems are symmetric and positive definite. Thus the existence and uniquencess of the numerical solution are assured. When only one vertical layer is specified, this method reduces as a special case to a semi-implicit scheme for solving the corresponding two-dimensional shallow water equations. The resulting two- and three-dimensional algorithm has been shown to be fast, accurate and mass-conservative and can also be applied to simulate flooding and drying of tidal mud-flats in conjunction with three-dimensional flows. Furthermore, the resulting algorithm is fully vectorizable for an efficient implementation on modern vector computers.

  16. Tools to Perform Local Dense 3D Reconstruction of Shallow Water Seabed.

    PubMed

    Avanthey, Loïca; Beaudoin, Laurent; Gademer, Antoine; Roux, Michel

    2016-05-17

    Tasks such as distinguishing or identifying individual objects of interest require the production of dense local clouds at the scale of these individual objects of interest. Due to the physical and dynamic properties of an underwater environment, the usual dense matching algorithms must be rethought in order to be adaptive. These properties also imply that the scene must be observed at close range. Classic robotized acquisition systems are oversized for local studies in shallow water while the systematic acquisition of data is not guaranteed with divers. We address these two major issues through a multidisciplinary approach. To efficiently acquire on-demand stereoscopic pairs using simple logistics in small areas of shallow water, we devised an agile light-weight dedicated system which is easy to reproduce. To densely match two views in a reliable way, we devised a reconstruction algorithm that automatically accounts for the dynamics, variability and light absorption of the underwater environment. Field experiments in the Mediterranean Sea were used to assess the results.

  17. Analysis of nonlinear shallow water waves in a tank by concentrated mass model

    NASA Astrophysics Data System (ADS)

    Ishikawa, Satoshi; Kondou, Takahiro; Matsuzaki, Kenichiro; Yamamura, Satoshi

    2016-06-01

    The sloshing of liquid in a tank is an important engineering problem. For example, liquid storage tanks in industrial facilities can be damaged by earthquakes, and conversely liquid tanks, called tuned liquid damper, are often used as passive mechanical dampers. The water depth is less often than the horizontal length of the tank. In this case, shallow water wave theory can be applied, and the results indicate that the surface waveform in a shallow excited tank exhibits complex behavior caused by nonlinearity and dispersion of the liquid. This study aims to establish a practical analytical model for this phenomenon. A model is proposed that consists of masses, connecting nonlinear springs, connecting dampers, base support dampers, and base support springs. The characteristics of the connecting nonlinear springs are derived from the static and dynamic pressures. The advantages of the proposed model are that nonlinear dispersion is considered and that the problem of non-uniform water depth can be addressed. To confirm the validity of the model, numerical results obtained from the model are compared with theoretical values of the natural frequencies of rectangular and triangular tanks. Numerical results are also compared with experimental results for a rectangular tank. All computational results agree well with the theoretical and experimental results. Therefore, it is concluded that the proposed model is valid for the numerical analysis of nonlinear shallow water wave problems.

  18. A standard test set for numerical approximations to the shallow water equations in spherical geometry

    SciTech Connect

    Williamson, D.L.; Hack, J.J.; Jakob, R.; Swarztrauber, P.N. ); Drake, J.B. )

    1991-08-01

    A suite of seven test cases is proposed for the evaluation of numerical methods intended for the solution of the shallow water equations in spherical geometry. The shallow water equations exhibit the major difficulties associated with the horizontal dynamical aspects of atmospheric modeling on the spherical earth. These cases are designed for use in the evaluation of numerical methods proposed for climate modeling and to identify the potential trade-offs which must always be made in numerical modeling. Before a proposed scheme is applied to a full baroclinic atmospheric model it must perform well on these problems in comparison with other currently accepted numerical methods. The cases are presented in order of complexity. They consist of advection across the poles, steady state geostrophically balanced flow of both global and local scales, forced nonlinear advection of an isolated low, zonal flow impinging on an isolated mountain, Rossby-Haurwitz waves and observed atmospheric states. One of the cases is also identified as a computer performance/algorithm efficiency benchmark for assessing the performance of algorithms adapted to massively parallel computers. 31 refs.

  19. Airborne mapping of shallow water bathymetry in the optically complex waters of the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Vahtmäe, Ele; Kutser, Tiit

    2016-04-01

    Accurate determination of the water depth is important for marine spatial planning, producing maritime charts for navigation, seabed morphology studies, and carrying out different activities in the coastal waters. Bathymetric data are lacking foremost in the shallow water regions as those areas are often inaccessible to the hydrographic ships carrying out echo sounding measurements. Remote sensing technology can be used as an alternative for shallow water bathymetry mapping. Varieties of empirical methods have been proposed for bathymetry retrieval, where the relationship between remotely sensed radiance of the water body and the water depth at sampled locations was established empirically. Two most widely used depth derivation methods, the linear band model proposed by Lyzenga (1978, 1985, 2006), and the log-transformed band ratio model proposed by Stumpf et al. (2003), were applied to the different preprocessing level airborne Hyspex hyperspectral images from the optically complex Baltic Sea area and evaluated for accuracy. Results showed that the Lyzenga linear band model outperformed the Stumpf log-transformed band ratio model. The best results were achieved with the atmospherically corrected images. The application of glint correction did not improve, but even reduced the accuracy of bathymetric maps.

  20. Shallow water benthic imaging and substrate characterization using recreational-grade sidescan-sonar

    USGS Publications Warehouse

    Buscombe, Daniel D.

    2017-01-01

    In recent years, lightweight, inexpensive, vessel-mounted ‘recreational grade’ sonar systems have rapidly grown in popularity among aquatic scientists, for swath imaging of benthic substrates. To promote an ongoing ‘democratization’ of acoustical imaging of shallow water environments, methods to carry out geometric and radiometric correction and georectification of sonar echograms are presented, based on simplified models for sonar-target geometry and acoustic backscattering and attenuation in shallow water. Procedures are described for automated removal of the acoustic shadows, identification of bed-water interface for situations when the water is too turbid or turbulent for reliable depth echosounding, and for automated bed substrate classification based on singlebeam full-waveform analysis. These methods are encoded in an open-source and freely-available software package, which should further facilitate use of recreational-grade sidescan sonar, in a fully automated and objective manner. The sequential correction, mapping, and analysis steps are demonstrated using a data set from a shallow freshwater environment.

  1. A Vorticity-Divergence Global Semi-Lagrangian Spectral Model for the Shallow Water Equations

    SciTech Connect

    Drake, JB

    2001-11-30

    The shallow water equations modeling flow on a sphere are useful for the development and testing of numerical algorithms for atmospheric climate and weather models. A new formulation of the shallow water equations is derived which exhibits an advective form for the vorticity and divergence. This form is particularly well suited for numerical computations using a semi-Lagrangian spectral discretization. A set of test problems, standard for the shallow water equations on a sphere, are solved and results compared with an Eulerian spectral model. The semi-Lagrangian transport method was introduced into atmospheric modeling by Robert, Henderson, and Turnbull. A formulation based on a three time level integration scheme in conjunction with a finite difference spatial discretization was studied by Ritchie. Two time level grid point schemes were derived by Bates et al. Staniforth and Cote survey developments of the application of semi-Lagrangian transport (SLT) methods for shallow water models and for numerical weather prediction. The spectral (or spherical harmonic transform) method when combined with a SLT method is particularly effective because it allows for long time steps avoiding the Courant-Friedrichs-Lewy (CFL) restriction of Eulerian methods, while retaining accurate (spectral) treatment of the spatial derivatives. A semi-implicit, semi-Lagrangian formulation with spectral spatial discretization is very effective because the Helmholz problem arising from the semi-implicit time integration can be solved cheaply in the course of the spherical harmonic transform. The combination of spectral, semi-Lagrangian transport with a semi-implicit time integration schemes was first proposed by Ritchie. A advective formulation using vorticity and divergence was introduced by Williamson and Olson. They introduce the vorticity and divergence after the application of the semi-Lagrangian discretization. The semi-Lagrangian formulation of Williamson and Olson and Bates et al. has

  2. Effects of UV radiation on the growth, photosynthetic and photoprotective components, and reproduction of the Caribbean shallow-water coral Porites furcata

    NASA Astrophysics Data System (ADS)

    Torres-Pérez, J. L.; Armstrong, R. A.

    2012-12-01

    Shallow reef corals can frequently be subjected to high doses of ultraviolet radiation [280-400 nm (UVR)] and have developed mechanisms to cope with this. Nevertheless, slight changes in this stressor may impact their physiology and ultimately their survival. Here, we present results on the effects of artificially enhanced UVR on the growth, reproduction, production of photosynthetic pigments and photoprotective compounds of the Caribbean shallow-water branching coral Porites furcata. Corals were randomly located in one of the three different treatments: normal photosynthetically active radiation (PAR) + UVR; normal PAR+ enhanced UVR; normal PAR+ depleted UVR. Growth rates were measured using the Alizarin red staining method, photosynthetic pigments as well as mycosporine-like amino acids (MAAs) were quantified through high-performance liquid chromatography, and fecundity was estimated after histological analyses. Growth and photosynthetic pigment concentration were negatively correlated with increased UVR, compared to controls exposed to normal UVR. A significant increase in MAAs was also found in colonies under enhanced UVR. Based on their respective concentrations, the primary mycosporine-glycine (λmax = 310 nm) and shinorine (λmax = 333 nm) are the main contributors to UVR absorption in this species, while the levels of the secondary MAA palythine (λmax = 320 nm) tripled toward the end of the 128 days of the experimental period. While several physical factors may influence reef coral physiology, the results suggest that slight increases in UVR can debilitate the skeletal constitution and severely reduce the fecundity of corals living in shallow waters.

  3. Hawkweed Control in Alaska

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several hawkweed species from Europe have escaped ornamental planting and have colonized roadsides and grasslands in south central and southeast Alaska. These plants form near monotypic stands, reducing plant diversity and decreasing pasture productivity. A replicated greenhouse study was conducted ...

  4. Twig and foliar biomass estimation equations for major plant species in the Tanana River basin of interior Alaska. Forest Service research paper

    SciTech Connect

    Yarie, J.; Mead, B.R.

    1988-09-01

    Equations are presented for estimating the twig, foliage, and combined biomass for 58 plant species in interior Alaska. The equations can be used for estimating biomass from percentage of the foliar cover of 10-centimeter layers in a vertical profile from 0 to 6 meters. Few differences were found in regressions of the same species between layers except when the ratio of foliar-to-twig biomass changed drastically between layers, for example, Rosa acicularis Lindl. Eighteen species were tested for regression differences between years. Thirteen showed no significant differences, five were different. Of these five, three were feather mosses for which live and dead biomass are easily confused when measured.

  5. Selected marine mammals of Alaska: species accounts with research and management recommendations

    SciTech Connect

    Lentfer, J.W.

    1988-01-01

    This book is the result of a need seen by the Marine Mammal Commission for a current summary of the biology and status of ten species of Alaskan marine mammals, including recommendations for research and management. Its purpose is to serve as a reference and working document as conservation and management plans are developed and implemented for the ten species.

  6. The role of Argopecten purpuratus shells structuring the soft bottom community in shallow waters of southern Peru

    NASA Astrophysics Data System (ADS)

    Lomovasky, Betina J.; Gamero, Patricia A.; Romero, Leonardo; Firstater, Fausto N.; Gamarra Salazar, Alex; Hidalgo, Fernando; Tarazona, Juan; Iribarne, Oscar O.

    2015-12-01

    Accumulation of Argopecten purpuratus shells often occurs after El Niño events in shallow waters of Independencia Bay (14°17‧S-76°10‧W; Pisco, Peru). Here we experimentally investigate the effects of their shell accumulation on macrobenthos assemblages in soft bottom, shallow areas of the bay. A field experiment (from May 2006 to May 2007), including four treatments with different coverage levels of empty shells of A. purpuratus, were randomly arranged in: (1) areas devoid of shells ("Empty" treatment: experimental control), (2) 50% of the plot area covered with shells haphazardly distributed over the bottom ("medium" treatment), (3) 100% of the plot area covered with shells, forming a 10 cm valve layer ("full" treatment) and (4) "natural control". We found a total of 124 taxa throughout the experiment. Polychaetes, crustaceans and mollusks were the most abundant groups in "natural controls", dominated by the gastropod Nassarius gayi and the polychaetes Prionospio peruana, Platynereis bicanaliculata and Mediomastus branchiferus. The abundance of individuals (N) and the species richness (S) were higher in the "medium" treatment, but only in one month under positive sea bottom thermal anomalies. Similarity analysis (Bray-Curtis) showed that "natural control", "empty" and "full" treatments were more similar among them than the "medium" treatment. Multidimensional analysis showed no clear species association among treatments and a higher grouping among the samplings of Jun-06, Aug-06 and Nov-06. Our results also showed that the commercial crab Romaleon polyodon and the polyplacophora Tonicia elegans were positively affected by shell accumulations ("medium" treatment), while the limpet Fissurella crassa was negatively affected. Our study shows that directly by changing habitat structure or indirectly by changing sediment characteristics, the addition of scallop shells to the soft bottom can modify the macrobenthic assemblage; however, the seasonal oceanographic

  7. Metagenetic community analysis of microbial eukaryotes illuminates biogeographic patterns in deep-sea and shallow water sediments

    PubMed Central

    Bik, Holly M.; Sung, Way; De Ley, Paul; Baldwin, James G.; Sharma, Jyotsna; Rocha-Olivares, Axayácatl; Thomas, W. Kelley

    2011-01-01

    Summary Microbial eukaryotes (nematodes, protists, fungi, etc., loosely referred to as meiofauna) are ubiquitous in marine sediments and likely play pivotal roles in maintaining ecosystem function. Although the deep-sea benthos represents one of the world’s largest habitats, we lack a firm understanding of the biodiversity and community interactions amongst meiobenthic organisms in this ecosystem. Within this vast environment key questions concerning the historical genetic structure of species remain a mystery, yet have profound implications for our understanding of global biodiversity and how we perceive and mitigate the impact of environmental change and anthropogenic disturbance. Using a metagenetic approach, we present an assessment of microbial eukaryote communities across depth (shallow water to abyssal) and ocean basins (deep-sea Pacific and Atlantic). Within the 12 sites examined, our results suggest that some taxa can maintain eurybathic ranges and cosmopolitan deep-sea distributions, but the majority of species appear to be regionally restricted. For OCTUs reporting wide distributions, there appears to be a taxonomic bias towards a small subset of taxa in most phyla; such bias may be driven by specific life history traits amongst these organisms. In addition, low genetic divergence between geographically disparate deep-sea sites suggests either a shorter coalescence time between deep-sea regions or slower rates of evolution across this vast oceanic ecosystem. While high-throughput studies allow for broad assessment of genetic patterns across microbial eukaryote communities, intragenomic variation in rRNA gene copies and the patchy coverage of reference databases currently present substantial challenges for robust taxonomic interpretations of eukaryotic datasets. PMID:21985648

  8. Evolution and origin of sympatric shallow-water morphotypes of Lake Trout, Salvelinus namaycush, in Canada's Great Bear Lake.

    PubMed

    Harris, L N; Chavarie, L; Bajno, R; Howland, K L; Wiley, S H; Tonn, W M; Taylor, E B

    2015-01-01

    Range expansion in north-temperate fishes subsequent to the retreat of the Wisconsinan glaciers has resulted in the rapid colonization of previously unexploited, heterogeneous habitats and, in many situations, secondary contact among conspecific lineages that were once previously isolated. Such ecological opportunity coupled with reduced competition likely promoted morphological and genetic differentiation within and among post-glacial fish populations. Discrete morphological forms existing in sympatry, for example, have now been described in many species, yet few studies have directly assessed the association between morphological and genetic variation. Morphotypes of Lake Trout, Salvelinus namaycush, are found in several large-lake systems including Great Bear Lake (GBL), Northwest Territories, Canada, where several shallow-water forms are known. Here, we assess microsatellite and mitochondrial DNA variation among four morphotypes of Lake Trout from the five distinct arms of GBL, and also from locations outside of this system to evaluate several hypotheses concerning the evolution of morphological variation in this species. Our data indicate that morphotypes of Lake Trout from GBL are genetically differentiated from one another, yet the morphotypes are still genetically more similar to one another compared with populations from outside of this system. Furthermore, our data suggest that Lake Trout colonized GBL following dispersal from a single glacial refugium (the Mississippian) and support an intra-lake model of divergence. Overall, our study provides insights into the origins of morphological and genetic variation in post-glacial populations of fishes and provides benchmarks important for monitoring Lake Trout biodiversity in a region thought to be disproportionately susceptible to impacts from climate change.

  9. Evolution and origin of sympatric shallow-water morphotypes of Lake Trout, Salvelinus namaycush, in Canada's Great Bear Lake

    PubMed Central

    Harris, L N; Chavarie, L; Bajno, R; Howland, K L; Wiley, S H; Tonn, W M; Taylor, E B

    2015-01-01

    Range expansion in north-temperate fishes subsequent to the retreat of the Wisconsinan glaciers has resulted in the rapid colonization of previously unexploited, heterogeneous habitats and, in many situations, secondary contact among conspecific lineages that were once previously isolated. Such ecological opportunity coupled with reduced competition likely promoted morphological and genetic differentiation within and among post-glacial fish populations. Discrete morphological forms existing in sympatry, for example, have now been described in many species, yet few studies have directly assessed the association between morphological and genetic variation. Morphotypes of Lake Trout, Salvelinus namaycush, are found in several large-lake systems including Great Bear Lake (GBL), Northwest Territories, Canada, where several shallow-water forms are known. Here, we assess microsatellite and mitochondrial DNA variation among four morphotypes of Lake Trout from the five distinct arms of GBL, and also from locations outside of this system to evaluate several hypotheses concerning the evolution of morphological variation in this species. Our data indicate that morphotypes of Lake Trout from GBL are genetically differentiated from one another, yet the morphotypes are still genetically more similar to one another compared with populations from outside of this system. Furthermore, our data suggest that Lake Trout colonized GBL following dispersal from a single glacial refugium (the Mississippian) and support an intra-lake model of divergence. Overall, our study provides insights into the origins of morphological and genetic variation in post-glacial populations of fishes and provides benchmarks important for monitoring Lake Trout biodiversity in a region thought to be disproportionately susceptible to impacts from climate change. PMID:25204304

  10. Seasonal use of shallow water habitat in the Lower Snake River reservoirs by juvenile fall Chinook salmon

    USGS Publications Warehouse

    Tiffan, Kenneth F.; Connor, William P.

    2012-01-01

    The U.S. Army Corps of Engineers (COE) is preparing a long term management plan for sediments that affect the authorized project purposes of the Lower Granite, Little Goose, Lower Monumental, and Ice Harbor reservoirs (hereafter, the lower Snake River reservoirs), and the area from the mouth of the Snake River to Ice Harbor Dam. We conducted a study from spring 2010 through winter 2011 to describe the habitat use by juvenile Chinook salmon within a selected group of shallow water habitat complexes (< 6 m deep) in the lower Snake River reservoirs to help inform the long-term plan. Natural fry and parr were present within all four shallow water habitat complexes that we studied from early spring through early summer, and parr ( = 40,345 ± 18,800 [error bound]) were more abundant than fry ( = 24,615 ± 5,701). Water < 2 m deep was highly used for rearing by natural fall Chinook salmon subyearlings (fry and parr combined; hereafter natural subyearlings) based on duration of use and relative group abundances during spring and summer, whereas the 2–6 m depth interval was more highly used by migratory hatchery fall Chinook salmon subyearlings and spring, summer, and fall Chinook salmon yearlings. Overall mean spring-summer apparent density of natural subyearlings was 15.5 times higher within the < 2 m depth interval than within the 2–6 m depth interval. Density of natural subyearlings also decreased as the distance a given shallow water habitat complex was located from the riverine spawning areas increased. Reservoir-type juveniles (or fish likely destined to become reservoir-type juveniles) were present in the lower Snake River reservoirs from fall 2010 through winter 2011; however, use of shallow water habitat by reservoir-type juveniles was limited during our study. We only collected 38 reservoir-type juveniles in shallow water habitat sites in beach and lampara seines during the fall. Radiotelemetry data revealed that though many tagged fish passed shallow water

  11. Toward the Application of the Implicit Particle Filter to Real Data in a Shallow Water Model of the Nearshore Ocean

    NASA Astrophysics Data System (ADS)

    Miller, R.

    2015-12-01

    Following the success of the implicit particle filter in twin experiments with a shallow water model of the nearshore environment, the planned next step is application to the intensive Sandy Duck data set, gathered at Duck, NC. Adaptation of the present system to the Sandy Duck data set will require construction and evaluation of error models for both the model and the data, as well as significant modification of the system to allow for the properties of the data set. Successful implementation of the particle filter promises to shed light on the details of the capabilities and limitations of shallow water models of the nearshore ocean relative to more detailed models. Since the shallow water model admits distinct dynamical regimes, reliable parameter estimation will be important. Previous work by other groups give cause for optimism. In this talk I will describe my progress toward implementation of the new system, including problems solved, pitfalls remaining and preliminary results

  12. Observation of dispersive shock waves developing from initial depressions in shallow water

    NASA Astrophysics Data System (ADS)

    Trillo, S.; Klein, M.; Clauss, G. F.; Onorato, M.

    2016-10-01

    We investigate surface gravity waves in a shallow water tank, in the limit of long wavelengths. We report the observation of non-stationary dispersive shock waves rapidly expanding over a 90 m flume. They are excited by means of a wave maker that allows us to launch a controlled smooth (single well) depression with respect to the unperturbed surface of the still water, a case that contains no solitons. The dynamics of the shock waves are observed at different levels of nonlinearity equivalent to a different relative smallness of the dispersive effect. The observed undulatory behavior is found to be in good agreement with the dynamics described in terms of a Korteweg-de Vries equation with evolution in space, though in the most nonlinear cases the description turns out to be improved over the quasi linear trailing edge of the shock by modeling the evolution in terms of the integro-differential (nonlocal) Whitham equation.

  13. An unstructured grid, three-dimensional model based on the shallow water equations

    USGS Publications Warehouse

    Casulli, V.; Walters, R.A.

    2000-01-01

    A semi-implicit finite difference model based on the three-dimensional shallow water equations is modified to use unstructured grids. There are obvious advantages in using unstructured grids in problems with a complicated geometry. In this development, the concept of unstructured orthogonal grids is introduced and applied to this model. The governing differential equations are discretized by means of a semi-implicit algorithm that is robust, stable and very efficient. The resulting model is relatively simple, conserves mass, can fit complicated boundaries and yet is sufficiently flexible to permit local mesh refinements in areas of interest. Moreover, the simulation of the flooding and drying is included in a natural and straightforward manner. These features are illustrated by a test case for studies of convergence rates and by examples of flooding on a river plain and flow in a shallow estuary. Copyright ?? 2000 John Wiley & Sons, Ltd.

  14. Sloshing-induced slamming in screen-equipped rectangular tanks in shallow-water conditions

    NASA Astrophysics Data System (ADS)

    Wei, Zhi-Jun; Faltinsen, Odd Magnus; Lugni, Claudio; Yue, Qian-Jin

    2015-03-01

    Sloshing-induced slamming in a rectangular tank with centralized slat-screens with high solidity ratios was experimentally studied under nearly two-dimensional shallow-water conditions with large-amplitude harmonic lateral excitation. The main objective was to identify the solidity ratio that provides an optimal suppressing function on the free-surface elevation and slamming pressure on the vertical tank walls with a frequency domain containing the three lowest natural sloshing frequencies in a clean tank with a water depth-to-tank length ratio of h/l = 0.125 and a high forced sway amplitude. The experiments show that the optimal solidity ratio among four considered slat-screens is approximately 0.6-0.7 for the applied filling level and excitation amplitude in the examined forced frequency range. The results have potential applications in areas such as swash bulkhead design and liquefied-cargo tank design in ship and offshore engineering.

  15. Accelerating Time Integration for the Shallow Water Equations on the Sphere Using GPUs

    SciTech Connect

    Archibald, R.; Evans, K. J.; Salinger, A.

    2015-06-01

    The push towards larger and larger computational platforms has made it possible for climate simulations to resolve climate dynamics across multiple spatial and temporal scales. This direction in climate simulation has created a strong need to develop scalable time-stepping methods capable of accelerating throughput on high performance computing. This work details the recent advances in the implementation of implicit time stepping on a spectral element cube-sphere grid using graphical processing units (GPU) based machines. We demonstrate how solvers in the Trilinos project are interfaced with ACME and GPU kernels can significantly increase computational speed of the residual calculations in the implicit time stepping method for the shallow water equations on the sphere. We show the optimization gains and data structure reorganization that facilitates the performance improvements.

  16. Shallow-water acoustic tomography from angle measurements instead of travel-time measurements.

    PubMed

    Aulanier, Florian; Nicolas, Barbara; Mars, Jérôme I; Roux, Philippe; Brossier, Romain

    2013-10-01

    For shallow-water waveguides and mid-frequency broadband acoustic signals, ocean acoustic tomography (OAT) is based on the multi-path aspect of wave propagation. Using arrays in emission and reception and advanced array processing, every acoustic arrival can be isolated and matched to an eigenray that is defined not only by its travel time but also by its launch and reception angles. Classically, OAT uses travel-time variations to retrieve sound-speed perturbations; this assumes very accurate source-to-receiver clock synchronization. This letter uses numerical simulations to demonstrate that launch-and-reception-angle tomography gives similar results to travel-time tomography without the same requirement for high-precision synchronization.

  17. A Kalman filter for a two-dimensional shallow-water model

    NASA Technical Reports Server (NTRS)

    Parrish, D. F.; Cohn, S. E.

    1985-01-01

    A two-dimensional Kalman filter is described for data assimilation for making weather forecasts. The filter is regarded as superior to the optimal interpolation method because the filter determines the forecast error covariance matrix exactly instead of using an approximation. A generalized time step is defined which includes expressions for one time step of the forecast model, the error covariance matrix, the gain matrix, and the evolution of the covariance matrix. Subsequent time steps are achieved by quantifying the forecast variables or employing a linear extrapolation from a current variable set, assuming the forecast dynamics are linear. Calculations for the evolution of the error covariance matrix are banded, i.e., are performed only with the elements significantly different from zero. Experimental results are provided from an application of the filter to a shallow-water simulation covering a 6000 x 6000 km grid.

  18. Solving Two-Mode Shallow Water Equations Using Finite Volume Methods

    NASA Astrophysics Data System (ADS)

    Cheng, Y.

    2015-12-01

    We develop and study numerical methods for the two-mode shallow water equations recently proposed in [S. STECHMANN, A. MAJDA, and B. KHOUIDER, Theor. Comput. Fluid Dynamics, 22 (2008), pp. 407-432]. Designing a reliable numerical method for this system is a challenging task due to its conditional hyperbolicity and the presence of nonconservative terms. We present several numerical approaches — two operator splitting methods (based on either Roe-type upwind or central-upwind scheme), a central-upwind scheme and a path-conservative central-upwind scheme — and test their performance in a number of numerical experiments. The obtained results demonstrate that a careful numerical treatment of nonconservative terms is crucial for designing a robust and highly accurate numerical method. This is a joint work with M. J. Castro Díaz, A. Chertock and A. Kurganov.

  19. Semi-Lagrangian integration of a grid-point shallow water model on the sphere

    NASA Technical Reports Server (NTRS)

    Mcdonald, A.; Bates, J. R.

    1988-01-01

    This paper describes a semi-Lagrangian technique for integrating the equations of motion on the global domain. The technique uses an auxiliary spherical coordinate system at each near-polar gridpoint of the latitude-longitude grid; the auxiliary system is obtained by a rotation such that the new equator passes through the gridpoint in question and the new coordinate directions coincide with those of the original system at that point. The technique was applied to the shallow water equations, incorporating a semiimplicit treatment of the adjustment terms on a C-grid, with two-time levels. A five day integration was successfully carried out for a situation involving strong cross-polar flow. No filtering or diffusion was required to maintain stability over a five day period.

  20. Multiquadric and Compactly Supported Radial Basis Functions for Shallow Water Equations

    NASA Astrophysics Data System (ADS)

    Alhuri, Y.; Taik, A.; Naji, A.

    2009-04-01

    Meshfree methods have gained much attention in recent years, not only in the mathematics but also in the engineering community. The computer and numerical methods are powerful tools of analysing wide rang of engineering and industrial application. For long time researchers recognised problems when using a mesh-based method. Developing the meshless methods overcome these problems. In the present paper, we present the application of both the global and the compactly supported radial basis functions (CSRBFs) for solving a system of shallow water hydrodynamic model for marine environments. As the technique is based on the collocation formulation and does not require the generation of a grid and any integral evaluation, the technique is considered as purely meshless method. The Computational efficiency and accuracy of both used functions are verified by comparing the analytic and observed solution.

  1. Thermal regime of shallow water bodies in the coastal tundra zone of the Hudson Bay Lowlands

    NASA Astrophysics Data System (ADS)

    Duguay, C. R.; Soliman, A. S.; Macrae, M. L.

    2011-12-01

    Many shallow lakes and ponds of the Arctic/sub-Arctic contain thick, organic-rich sediments, which have the potential to release significant amounts of CO2 or CH4 to the atmosphere if sediment decomposition rates increase in response to warmer temperatures caused by global warming. This may be exacerbated by a deepening of the seasonal sediment thaw depth in small water bodies that are underlain by permafrost. An important step in linking climatic conditions to rates of organic matter decomposition and gas production from shallow water bodies is an improved understanding of the thermal properties of lake sediments and how sediment temperatures fluctuate in response to changing air temperatures. This knowledge is also important if the ratio of terrestrial to aquatic landscape units in cold regions changes under a warmer climate. One approach that has been used in terrestrial permafrost environments is the examination of how mean annual permafrost surface temperature deviates from mean annual 2-m screen height air temperature (MAAT). The offset between MAAT and the mean annual sediment surface temperature (MASST) has been found to be much larger in deep aquatic systems (greater than 10 m) than in terrestrial permafrost systems due to the presence of the water column that can efficiently transfer heat through mixing. However, the efficiency of heat transfer in shallow water bodies is expected to larger in summer (thawed) than in winter (frozen) conditions, when thermal energy must move by conduction alone. The present study examined the efficiency of sediment heat transfer in shallow water bodies (less than 3 m) during summer and winter periods. Air, sediment and water temperatures of three shallow water bodies in the coastal tundra zone of the Hudson Bay Lowlands near Churchill, Manitoba, Canada were monitored (December 2009-August 2011). Arrays of thermistors and heat pulse probes were placed at 10 cm increments between 20 cm above the water/sediment interface and

  2. Accelerating Time Integration for the Shallow Water Equations on the Sphere Using GPUs

    DOE PAGES

    Archibald, R.; Evans, K. J.; Salinger, A.

    2015-06-01

    The push towards larger and larger computational platforms has made it possible for climate simulations to resolve climate dynamics across multiple spatial and temporal scales. This direction in climate simulation has created a strong need to develop scalable time-stepping methods capable of accelerating throughput on high performance computing. This work details the recent advances in the implementation of implicit time stepping on a spectral element cube-sphere grid using graphical processing units (GPU) based machines. We demonstrate how solvers in the Trilinos project are interfaced with ACME and GPU kernels can significantly increase computational speed of the residual calculations in themore » implicit time stepping method for the shallow water equations on the sphere. We show the optimization gains and data structure reorganization that facilitates the performance improvements.« less

  3. A potential enstrophy and energy conserving scheme for the shallow water equations

    NASA Technical Reports Server (NTRS)

    Arakawa, A.; Lamb, V. R.

    1981-01-01

    To improve the simulation of nonlinear aspects of the flow over steep topography, a potential enstrophy and energy conserving scheme for the shallow water equations is derived. It is pointed out that a family of schemes can conserve total energy for general flow and potential enstrophy for flow with no mass flux divergence. The newly derived scheme is a unique member of this family, that conserves both potential enstrophy and energy for general flow. Comparison by means of numerical experiment with a scheme that conserves (potential) enstrophy for purely horizontal nondivergent flow demonstrated the considerable superiority of the newly derived potential enstrophy and energy conserving scheme, not only in suppressing a spurious energy cascade but also in determining the overall flow regime. The potential enstrophy and energy conserving scheme for a spherical grid is also presented.

  4. Lagrangian-Eulerian dynamics of breaking shallow water waves through tracer tracking of fluid elements.

    PubMed

    Pen, Ue-Yu; Chang, Mei-Chu; I, Lin

    2013-02-01

    We experimentally investigate the Lagrangian-Eulerian dynamics of fluid motion and wave-form evolution for a breaking shallow water wave approaching a slope by tracking tracer motions. It is found that, before breaking, the surface element can climb over the crest and exhibits cyclic oscillation with small forward drift. The increasing asymmetric tangential compression (accumulation) and rarefaction (depletion) in the crest front and the crest are the keys for the crest front steepening with the increasing particle cyclic excursion and forward Stoke drift. Eventually, the surface layer cannot climb over the crest with the vertical front. It curls up and forms an overhanging plunging jet leading the crest, while the lower flow still can reach the crest rear. This process leads to wave breaking with the rapid drop of crest height and the transition from slow divergence to rapid divergence of the adjacent fluid trajectories.

  5. Observations of the R reflector and sediment interface reflection at the Shallow Water '06 Central Site.

    PubMed

    Choi, Jee Woong; Dahl, Peter H; Goff, John A

    2008-09-01

    Acoustic bottom-interacting measurements from the Shallow Water '06 experiment experiment (frequency range 1-20 kHz) are presented. These are co-located with coring and stratigraphic studies showing a thin (approximately 20 cm) higher sound speed layer overlaying a thicker (approximately 20 m) lower sound speed layer ending at a high-impedance reflector (R reflector). Reflections from the R reflector and analysis of the bottom reflection coefficient magnitude for the upper two sediment layers confirm both these features. Geoacoustic parameters are estimated, dispersion effects addressed, and forward modeling using the parabolic wave equation undertaken. The reflection coefficient measurements suggest a nonlinear attenuation law for the thin layer of sandy sediments.

  6. Method of moving frames to solve the shallow water equations on arbitrary rotating curved surfaces

    NASA Astrophysics Data System (ADS)

    Chun, S.; Eskilsson, C.

    2017-03-01

    A novel numerical scheme is proposed to solve the shallow water equations (SWEs) on arbitrary rotating curved surfaces. Based on the method of moving frames (MMF) in which the geometry is represented by orthonormal vectors, the proposed scheme not only has the fewest dimensionality both in space and time, but also does not require either of metric tensors, composite meshes, or the ambient space. The MMF-SWE formulation is numerically discretized using the discontinuous Galerkin method of arbitrary polynomial order p in space and an explicit Runge-Kutta scheme in time. The numerical model is validated against six standard tests on the sphere and the optimal order of convergence of p + 1 is numerically demonstrated. The MMF-SWE scheme is also demonstrated for its efficiency and stability on the general rotating surfaces such as ellipsoid, irregular, and non-convex surfaces.

  7. An unstructured grid, three-dimensional model based on the shallow water equations

    NASA Astrophysics Data System (ADS)

    Casulli, Vincenzo; Walters, Roy A.

    2000-02-01

    A semi-implicit finite difference model based on the three-dimensional shallow water equations is modified to use unstructured grids. There are obvious advantages in using unstructured grids in problems with a complicated geometry. In this development, the concept of unstructured orthogonal grids is introduced and applied to this model. The governing differential equations are discretized by means of a semi-implicit algorithm that is robust, stable and very efficient. The resulting model is relatively simple, conserves mass, can fit complicated boundaries and yet is sufficiently flexible to permit local mesh refinements in areas of interest. Moreover, the simulation of the flooding and drying is included in a natural and straightforward manner. These features are illustrated by a test case for studies of convergence rates and by examples of flooding on a river plain and flow in a shallow estuary. Copyright

  8. On the solutions of a model equation for shallow water waves of moderate amplitude

    NASA Astrophysics Data System (ADS)

    Mi, Yongsheng; Mu, Chunlai

    This paper is concerned with the Cauchy problem of a model equation for shallow water waves of moderate amplitude, which was proposed by A. Constantin and D. Lannes [The hydrodynamical relevance of the Camassa-Holmand Degasperis-Procesi equations, Arch. Ration. Mech. Anal. 192 (2009) 165-186]. First, the local well-posedness of the model equation is obtained in Besov spaces Bp,rs, p,r∈[1,∞], s>max{3/2,1+1/p} (which generalize the Sobolev spaces Hs) by using Littlewood-Paley decomposition and transport equation theory. Second, the local well-posedness in critical case (with s=3/2, p=2, r=1) is considered. Moreover, with analytic initial data, we show that its solutions are analytic in both variables, globally in space and locally in time. Finally, persistence properties on strong solutions are also investigated.

  9. Discontinuous Galerkin Method with Numerical Roe Flux for Spherical Shallow Water Equations

    NASA Astrophysics Data System (ADS)

    Yi, T.; Choi, S.; Kang, S.

    2013-12-01

    In developing the dynamic core of a numerical weather prediction model with discontinuous Galerkin method, a numerical flux at the boundaries of grid elements plays a vital role since it preserves the local conservation properties and has a significant impact on the accuracy and stability of numerical solutions. Due to these reasons, we developed the numerical Roe flux based on an approximate Riemann problem for spherical shallow water equations in Cartesian coordinates [1] to find out its stability and accuracy. In order to compare the performance with its counterpart flux, we used the Lax-Friedrichs flux, which has been used in many dynamic cores such as NUMA [1], CAM-DG [2] and MCore [3] because of its simplicity. The Lax-Friedrichs flux is implemented by a flux difference between left and right states plus the maximum characteristic wave speed across the boundaries of elements. It has been shown that the Lax-Friedrichs flux with the finite volume method is more dissipative and unstable than other numerical fluxes such as HLLC, AUSM+ and Roe. The Roe flux implemented in this study is based on the decomposition of flux difference over the element boundaries where the nonlinear equations are linearized. It is rarely used in dynamic cores due to its complexity and thus computational expensiveness. To compare the stability and accuracy of the Roe flux with the Lax-Friedrichs, two- and three-dimensional test cases are performed on a plane and cubed-sphere, respectively, with various numbers of element and polynomial order. For the two-dimensional case, the Gaussian bell is simulated on the plane with two different numbers of elements at the fixed polynomial orders. In three-dimensional cases on the cubed-sphere, we performed the test cases of a zonal flow over an isolated mountain and a Rossby-Haurwitz wave, of which initial conditions are the same as those of Williamson [4]. This study presented that the Roe flux with the discontinuous Galerkin method is less

  10. On the assimilation of SWOT type data into 2D shallow-water models

    NASA Astrophysics Data System (ADS)

    Frédéric, Couderc; Denis, Dartus; Pierre-André, Garambois; Ronan, Madec; Jérôme, Monnier; Jean-Paul, Villa

    2013-04-01

    In river hydraulics, assimilation of water level measurements at gauging stations is well controlled, while assimilation of images is still delicate. In the present talk, we address the richness of satellite mapped information to constrain a 2D shallow-water model, but also related difficulties. 2D shallow models may be necessary for small scale modelling in particular for low-water and flood plain flows. Since in both cases, the dynamics of the wet-dry front is essential, one has to elaborate robust and accurate solvers. In this contribution we introduce robust second order, stable finite volume scheme [CoMaMoViDaLa]. Comparisons of real like tests cases with more classical solvers highlight the importance of an accurate flood plain modelling. A preliminary inverse study is presented in a flood plain flow case, [LaMo] [HoLaMoPu]. As a first step, a 0th order data processing model improves observation operator and produces more reliable water level derived from rough measurements [PuRa]. Then, both model and flow behaviours can be better understood thanks to variational sensitivities based on a gradient computation and adjoint equations. It can reveal several difficulties that a model designer has to tackle. Next, a 4D-Var data assimilation algorithm used with spatialized data leads to improved model calibration and potentially leads to identify river discharges. All the algorithms are implemented into DassFlow software (Fortran, MPI, adjoint) [Da]. All these results and experiments (accurate wet-dry front dynamics, sensitivities analysis, identification of discharges and calibration of model) are currently performed in view to use data from the future SWOT mission. [CoMaMoViDaLa] F. Couderc, R. Madec, J. Monnier, J.-P. Vila, D. Dartus, K. Larnier. "Sensitivity analysis and variational data assimilation for geophysical shallow water flows". Submitted. [Da] DassFlow - Data Assimilation for Free Surface Flows. Computational software http

  11. Parametric instabilities in shallow water magnetohydrodynamics of astrophysical plasma in external magnetic field

    NASA Astrophysics Data System (ADS)

    Klimachkov, D. A.; Petrosyan, A. S.

    2017-01-01

    This article deals with magnetohydrodynamic (MHD) flows of a thin rotating layer of astrophysical plasma in external magnetic field. We use the shallow water approximation to describe thin rotating plasma layer with a free surface in a vertical external magnetic field. The MHD shallow water equations with external vertical magnetic field are revised by supplementing them with the equations that are consequences of the magnetic field divergence-free conditions and reveal the existence of third component of the magnetic field in such approximation providing its relation with the horizontal magnetic field. It is shown that the presence of a vertical magnetic field significantly changes the dynamics of the wave processes in astrophysical plasma compared to the neutral fluid and plasma layer in a toroidal magnetic field. The equations for the nonlinear wave packets interactions are derived using the asymptotic multiscale method. The equations for three magneto-Poincare waves interactions, for three magnetostrophic waves interactions, for the interactions of two magneto-Poincare waves and for one magnetostrophic wave and two magnetostrophic wave and one magneto-Poincare wave interactions are obtained. The existence of parametric decay and parametric amplifications is predicted. We found following four types of parametric decay instabilities: magneto-Poincare wave decays into two magneto-Poincare waves, magnetostrophic wave decays into two magnetostrophic waves, magneto-Poincare wave decays into one magneto-Poincare wave and one magnetostrophic wave, magnetostrophic wave decays into one magnetostrophic wave and one magneto-Poincare wave. Following mechanisms of parametric amplifications are found: parametric amplification of magneto-Poincare waves, parametric amplification of magnetostrophic waves, magneto-Poincare wave amplification in magnetostrophic wave presence and magnetostrophic wave amplification in magneto-Poincare wave presence. The instabilities growth rates

  12. Bottom Roughness and Bathymetry Estimation of 1-D Shallow Water Equations Model Using Ensemble Kalman Filter

    NASA Astrophysics Data System (ADS)

    Hooshyar, M.; Hagen, S. C.; Wang, D.

    2014-12-01

    Hydrodynamic models are widely applied to coastal areas in order to predict water levels and flood inundation and typically involve solving a form of the Shallow Water Equations (SWE). The SWE are routinely discretized by applying numerical methods, such as the finite element method. Like other numerical models, hydrodynamic models include uncertainty. Uncertainties are generated due to errors in the discrete approximation of coastal geometry, bathymetry, bottom friction and forcing functions such as tides and wind fields. Methods to counteract these uncertainties should always begin with improvements to physical characterization of: the geometric description through increased resolution, parameters that describe land cover variations in the natural and urban environment, parameters that enhance transfer of surface forcings to the water surface, open boundary forcings, and the wetting/drying brought upon by flood and ebb cycles. When the best possible physical representation is achieved, we are left with calibration and data assimilation to reduce model uncertainty. Data assimilation has been applied to coastal hydrodynamic models to better estimate system states and/or system parameters by incorporating observed data into the model. Kalman Filter is one of the most studied data assimilation methods that minimizes the mean square errors between model state estimations and the observed data in linear systems (Kalman , 1960). For nonlinear systems, as with hydrodynamic models, a variation of Kalman filter called Ensemble Kalman Filter (EnKF), is applied to update the system state according to error statistics in the context of Monte Carlo simulations (Evensen , 2003) & (Hitoshi et. al, 2014). In this research, Kalman Filter is incorporated to simultaneously estimate an influential parameter used in the shallow water equations, bottom roughness, and to adjust the physical feature of bathymetry. Starting from an initial estimate of bottom roughness and bathymetry, and

  13. Extreme Sea Conditions in Shallow Water: Estimation based on in-situ measurements

    NASA Astrophysics Data System (ADS)

    Le Crom, Izan; Saulnier, Jean-Baptiste

    2013-04-01

    The design of marine renewable energy devices and components is based, among others, on the assessment of the environmental extreme conditions (winds, currents, waves, and water level) that must be combined together in order to evaluate the maximal loads on a floating/fixed structure, and on the anchoring system over a determined return period. Measuring devices are generally deployed at sea over relatively short durations (a few months to a few years), typically when describing water free surface elevation, and extrapolation methods based on hindcast data (and therefore on wave simulation models) have to be used. How to combine, in a realistic way, the action of the different loads (winds and waves for instance) and which correlation of return periods should be used are highly topical issues. However, the assessment of the extreme condition itself remains a not-fully-solved, crucial, and sensitive task. Above all in shallow water, extreme wave height, Hmax, is the most significant contribution in the dimensioning process of EMR devices. As a case study, existing methodologies for deep water have been applied to SEMREV, the French marine energy test site. The interest of this study, especially at this location, goes beyond the simple application to SEMREV's WEC and floating wind turbines deployment as it could also be extended to the Banc de Guérande offshore wind farm that are planned close by. More generally to pipes and communication cables as it is a redundant problematic. The paper will first present the existing measurements (wave and wind on site), the prediction chain that has been developed via wave models, the extrapolation methods applied to hindcast data, and will try to formulate recommendations for improving this assessment in shallow water.

  14. Nonhydrostatic correction for shallow water equations with quadratic vertical pressure distribution: A Boussinesq-type equation

    NASA Astrophysics Data System (ADS)

    Jeschke, Anja; Behrens, Jörn

    2015-04-01

    In tsunami modeling, two different systems of dispersive long wave equations are common: The nonhydrostatic pressure correction for the shallow water equations derived out of the depth-integrated 3D Reynolds-averaged Navier-Stokes equations, and the category of Boussinesq-type equations obtained by an expansion in the nondimensional parameters for nonlinearity and dispersion in the Euler equations. The first system uses as an assumption a linear vertical interpolation of the nonhydrostatic pressure, whereas the second system's derivation includes an quadratic vertical interpolation for the nonhydrostatic pressure. In this case the analytical dispersion relations do not coincide. We show that the nonhydrostatic correction with a quadratic vertical interpolation yields an equation set equivalent to the Serre equations, which are 1D Boussinesq-type equations for the case of a horizontal bottom. Now, both systems yield the same analytical dispersion relation according up to the first order with the reference dispersion relation of the linear wave theory. The adjusted model is also compared to other Boussinesq-type equations. The numerical model with the nonhydrostatic correction for the shallow water equations uses Leapfrog timestepping stabilized with the Asselin filter and the P1-PNC1 finite element space discretization. The numerical dispersion relations are computed and compared by employing a testcase of a standing wave in a closed basin. All numerical values match their theoretical expectations. This work is funded by project ASTARTE - Assessment, Strategy And Risk Reduction for Tsunamis in Europe - FP7-ENV2013 6.4-3, Grant 603839. We acknowledge the support given by Geir K. Petersen from the University of Oslo.

  15. Shallow-water habitats as sources of fallback foods for hominins.

    PubMed

    Wrangham, Richard; Cheney, Dorothy; Seyfarth, Robert; Sarmiento, Esteban

    2009-12-01

    Underground storage organs (USOs) have been proposed as critical fallback foods for early hominins in savanna, but there has been little discussion as to which habitats would have been important sources of USOs. USOs consumed by hominins could have included both underwater and underground storage organs, i.e., from both aquatic and terrestrial habitats. Shallow aquatic habitats tend to offer high plant growth rates, high USO densities, and relatively continuous USO availability throughout the year. Baboons in the Okavango delta use aquatic USOs as a fallback food, and aquatic or semiaquatic USOs support high-density human populations in various parts of the world. As expected given fossilization requisites, the African early- to mid-Pleistocene shows an association of Homo and Paranthropus fossils with shallow-water and flooded habitats where high densities of plant-bearing USOs are likely to have occurred. Given that early hominins in the tropics lived in relatively dry habitats, while others occupied temperate latitudes, ripe, fleshy fruits of the type preferred by African apes would not normally have been available year round. We therefore suggest that water-associated USOs were likely to have been key fallback foods, and that dry-season access to aquatic habitats would have been an important predictor of hominin home range quality. This study differs from traditional savanna chimpanzee models of hominin origins by proposing that access to aquatic habitats was a necessary condition for adaptation to savanna habitats. It also raises the possibility that harvesting efficiency in shallow water promoted adaptations for habitual bipedality in early hominins.

  16. High-order finite-volume methods for the shallow-water equations on the sphere

    NASA Astrophysics Data System (ADS)

    Ullrich, Paul A.; Jablonowski, Christiane; van Leer, Bram

    2010-08-01

    This paper presents a third-order and fourth-order finite-volume method for solving the shallow-water equations on a non-orthogonal equiangular cubed-sphere grid. Such a grid is built upon an inflated cube placed inside a sphere and provides an almost uniform grid point distribution. The numerical schemes are based on a high-order variant of the Monotone Upstream-centered Schemes for Conservation Laws (MUSCL) pioneered by van Leer. In each cell the reconstructed left and right states are either obtained via a dimension-split piecewise-parabolic method or a piecewise-cubic reconstruction. The reconstructed states then serve as input to an approximate Riemann solver that determines the numerical fluxes at two Gaussian quadrature points along the cell boundary. The use of multiple quadrature points renders the resulting flux high-order. Three types of approximate Riemann solvers are compared, including the widely used solver of Rusanov, the solver of Roe and the new AUSM +-up solver of Liou that has been designed for low-Mach number flows. Spatial discretizations are paired with either a third-order or fourth-order total-variation-diminishing Runge-Kutta timestepping scheme to match the order of the spatial discretization. The numerical schemes are evaluated with several standard shallow-water test cases that emphasize accuracy and conservation properties. These tests show that the AUSM +-up flux provides the best overall accuracy, followed closely by the Roe solver. The Rusanov flux, with its simplicity, provides significantly larger errors by comparison. A brief discussion on extending the method to arbitrary order-of-accuracy is included.

  17. Competing turbulent cascades and eddy-wave interactions in shallow water equilibria

    NASA Astrophysics Data System (ADS)

    Weichman, Peter B.

    2017-03-01

    In recent work, Renaud, Venaille, and Bouchet (RVB) [Renaud et al., J. Stat. Phys. 163, 784 (2016), 10.1007/s10955-016-1496-x] revisit the equilibrium statistical mechanics theory of the shallow water equations, within a microcanonical approach, focusing on a more careful treatment of the energy partition between inertial gravity wave and eddy motions in the equilibrium state and deriving joint probability distributions for the corresponding dynamical degrees of freedom. The authors derive a Liouville theorem that determines the underlying phase space statistical measure, but then, through some physical arguments, actually compute the equilibrium statistics using a measure that violates this theorem, choosing equal volume vs equal area fluid parcels. Here, using a more convenient, but essentially equivalent, grand canonical approach, the full statistical theory consistent with the Liouville theorem is derived. The results reveal several significant differences from the previous results (1) The microscale wave motions lead to a strongly fluctuating thermodynamics, including long-range correlations, in contrast to the mean-field-like behavior found by RVB. The final effective model is equivalent to that of an elastic membrane with a nonlinear wave-renormalized surface tension. (2) Even when a mean-field approximation is made, a rather more complex joint probability distribution is revealed. Alternative physical arguments fully support the consistency of the results. Of course, the true fluid final steady state relies on dissipative processes not included in the shallow water equations, such as wave breaking and viscous effects, but it is argued that the current theory provides a more mathematically consistent starting point for future work aimed at assessing their impacts.

  18. Fracturing and flow: Investigations on the formation of shallow water sills on Europa

    NASA Astrophysics Data System (ADS)

    Craft, Kathleen L.; Patterson, G. Wes; Lowell, Robert P.; Germanovich, Leonid

    2016-08-01

    Double ridge tectonic features appear prominently and ubiquitously across the surface of Jupiter's icy moon Europa. Previous studies have interpreted flanking fractures observed along some of the ridges as indicators of stress resulting from the ridge loading and flexing of the ice shell above a shallow water body. Here, we investigate a shallow water sill emplacement process at a time when the shell is cooling and thickening and explore the conditions that would make such a system feasible on timescales of ridge formation. Results show that fracture initiation and transport of ocean water to shallow depths can realistically occur, although horizontal fracturing and sill lifetimes prove challenging. Finite element models demonstrate that mechanical layering or a fractured shell do not provide enough stress change to promote horizontal fracturing, but tidal forcing does result in a small amount of turn. Assuming it is possible for a shallow sill to form, a sill would convect internally and conduct heat out quickly, resulting in a short lifetime in comparison to an estimated flexure timeframe of 100 kyr suggested required for double ridge formation. Consideration of heat transfer and residence in the overlying ice, however, extends the flexure timeframe and multiple sill intrusions or replenishment with warm ocean water could prolong the effective sill lifetime. Though challenges still remain for sill formation at Europa, these analyses constrain the potential mechanisms for emplacement and indicate sills can act as viable options for supplying the heat needed for surface flexure. Further analyses and future missions to Europa will help to increase our understanding of these enigmatic processes.

  19. Airborne Laser Bathymetry for Documentation of Submerged Archaeological Sites in Shallow Water

    NASA Astrophysics Data System (ADS)

    Doneus, M.; Miholjek, I.; Mandlburger, G.; Doneus, N.; Verhoeven, G.; Briese, Ch.; Pregesbauer, M.

    2015-04-01

    Knowledge of underwater topography is essential to the understanding of the organisation and distribution of archaeological sites along and in water bodies. Special attention has to be paid to intertidal and inshore zones where, due to sea-level rise, coastlines have changed and many former coastal sites are now submerged in shallow water. Mapping the detailed inshore topography is therefore important to reconstruct former coastlines, identify sunken archaeological structures and locate potential former harbour sites. However, until recently archaeology has lacked suitable methods to provide the required topographical data of shallow underwater bodies. Our research shows that airborne topo-bathymetric laser scanner systems are able to measure surfaces above and below the water table over large areas in high detail using very short and narrow green laser pulses, even revealing sunken archaeological structures in shallow water. Using an airborne laser scanner operating at a wavelength in the green visible spectrum (532 nm) two case study areas in different environmental settings (Kolone, Croatia, with clear sea water; Lake Keutschach, Austria, with turbid water) were scanned. In both cases, a digital model of the underwater topography with a planimetric resolution of a few decimeters was measured. While in the clear waters of Kolone penetration depth was up to 11 meters, turbid Lake Keutschach allowed only to document the upper 1.6 meters of its underwater topography. Our results demonstrate the potential of this technique to map submerged archaeological structures over large areas in high detail providing the possibility for systematic, large scale archaeological investigation of this environment.

  20. Correlating Mediterranean shallow water deposits with global Oligocene-Miocene stratigraphy and oceanic events.

    PubMed

    Reuter, Markus; Piller, Werner E; Brandano, Marco; Harzhauser, Mathias

    2013-12-01

    Shallow-marine sediment records have the strong potential to display sensitive environmental changes in sedimentary geometries and skeletal content. However, the time resolution of most neritic carbonate records is not high enough to be compared with climatic events as recorded in the deep-sea sediment archives. In order to resolve the paleoceanographic and paleoclimatic changes during the Oligocene-Miocene transition in the Mediterranean shallow water carbonate systems with the best possible time resolution, we re-evaluated the Decontra section on the Maiella Platform (central Apennines, Italy), which acts as a reference for the correlation of Oligocene-Miocene shallow water deposits in the Mediterranean region. The 120-m-thick late Oligocene-late Miocene carbonate succession is composed of larger foraminiferal, bryozoan and corallinacean limestones interlayered with distinct planktonic foraminiferal carbonates representing a mostly outer neritic setting. Integrated multi-proxy and facies analyses indicate that CaCO3 and total organic carbon contents as well as gamma-ray display only local to regional processes on the carbonate platform and are not suited for stratigraphic correlation on a wider scale. In contrast, new biostratigraphic data correlate the Decontra stable carbon isotope record to the global deep-sea carbon isotope record. This links relative sea level fluctuations, which are reflected by facies and magnetic susceptibility changes, to third-order eustatic cycles. The new integrated bio-, chemo-, and sequence stratigraphic framework enables a more precise timing of environmental changes within the studied time interval and identifies Decontra as an important locality for correlating not only shallow and deep water sediments of the Mediterranean region but also on a global scale.

  1. Correlating Mediterranean shallow water deposits with global Oligocene–Miocene stratigraphy and oceanic events☆

    PubMed Central

    Reuter, Markus; Piller, Werner E.; Brandano, Marco; Harzhauser, Mathias

    2013-01-01

    Shallow-marine sediment records have the strong potential to display sensitive environmental changes in sedimentary geometries and skeletal content. However, the time resolution of most neritic carbonate records is not high enough to be compared with climatic events as recorded in the deep-sea sediment archives. In order to resolve the paleoceanographic and paleoclimatic changes during the Oligocene–Miocene transition in the Mediterranean shallow water carbonate systems with the best possible time resolution, we re-evaluated the Decontra section on the Maiella Platform (central Apennines, Italy), which acts as a reference for the correlation of Oligocene–Miocene shallow water deposits in the Mediterranean region. The 120-m-thick late Oligocene–late Miocene carbonate succession is composed of larger foraminiferal, bryozoan and corallinacean limestones interlayered with distinct planktonic foraminiferal carbonates representing a mostly outer neritic setting. Integrated multi-proxy and facies analyses indicate that CaCO3 and total organic carbon contents as well as gamma-ray display only local to regional processes on the carbonate platform and are not suited for stratigraphic correlation on a wider scale. In contrast, new biostratigraphic data correlate the Decontra stable carbon isotope record to the global deep-sea carbon isotope record. This links relative sea level fluctuations, which are reflected by facies and magnetic susceptibility changes, to third-order eustatic cycles. The new integrated bio-, chemo-, and sequence stratigraphic framework enables a more precise timing of environmental changes within the studied time interval and identifies Decontra as an important locality for correlating not only shallow and deep water sediments of the Mediterranean region but also on a global scale. PMID:25844021

  2. An adaptive multiblock high-order finite-volume method for solving the shallow-water equations on the sphere

    DOE PAGES

    McCorquodale, Peter; Ullrich, Paul; Johansen, Hans; ...

    2015-09-04

    We present a high-order finite-volume approach for solving the shallow-water equations on the sphere, using multiblock grids on the cubed-sphere. This approach combines a Runge--Kutta time discretization with a fourth-order accurate spatial discretization, and includes adaptive mesh refinement and refinement in time. Results of tests show fourth-order convergence for the shallow-water equations as well as for advection in a highly deformational flow. Hierarchical adaptive mesh refinement allows solution error to be achieved that is comparable to that obtained with uniform resolution of the most refined level of the hierarchy, but with many fewer operations.

  3. A Well-Balanced Central-Upwind Scheme for the 2D Shallow Water Equations on Triangular Meshes

    NASA Technical Reports Server (NTRS)

    Bryson, Steve; Levy, Doron

    2004-01-01

    We are interested in approximating solutions of the two-dimensional shallow water equations with a bottom topography on triangular meshes. We show that there is a certain flexibility in choosing the numerical fluxes in the design of semi-discrete Godunov-type central schemes. We take advantage of this fact to generate a new second-order, central-upwind method for the two-dimensional shallow water equations that is well-balanced. We demonstrate the accuracy of our method as well as its balance properties in a variety of examples.

  4. Shallow water analogue of the standing accretion shock instability: experimental demonstration and a two-dimensional model.

    PubMed

    Foglizzo, Thierry; Masset, Frédéric; Guilet, Jérôme; Durand, Gilles

    2012-02-03

    Despite the sphericity of the collapsing stellar core, the birth conditions of neutron stars can be highly nonspherical due to a hydrodynamical instability of the shocked accretion flow. Here we report the first laboratory experiment of a shallow water analogue, based on the physics of hydraulic jumps. Both the experiment and its shallow water modeling demonstrate a robust linear instability and nonlinear properties of symmetry breaking, in a system which is one million times smaller and about one hundred times slower than its astrophysical analogue.

  5. Species of coccidia (Apicomplexa: Eimeriidae) in shrews from Alaska, U.S.A., and northeastern Siberia, Russia, with description of two new species.

    PubMed

    Lynch, A J; Duszynski, D W

    2008-08-01

    Fecal samples (n = 636) from 10 species of shrews collected in Alaska (n = 540) and northeastern Siberia (n = 96) were examined for the presence of coccidia (Apicomplexa: Eimeriidae). Five distinct oocyst morphotypes were observed. Three types were consistent with oocysts of previously recognized coccidia species from other shrew hosts. These were Eimeria inyoni, E. vagrantis, and Isospora brevicauda, originally described from the inyo shrew (Sorex tenellus), dusky shrew (S. monticolus), and northern short-tailed shrew (Blarina brevicauda), respectively. We found 5 new host records for E. inyoni, 3 for E. vagrantis, and 3 for I. brevicauda. The 2 additional oocyst morphotypes, both from the tundra shrew (Sorex tundrensis), are putative new species. Sporulated oocysts of Eimeria beringiacea n. sp. are subspheroidal, 17.7 x 15.6 microm (14-24 x 13-20 microm) with a length (L)/width (W) ratio of 1.1 (1.0-1.4); these lack a micropyle (M), an oocyst residuum (OR), and a polar granule (PG). Sporocysts are ellipsoidal, 10.3 x 6.1 microm (7-14 x 4-8 microm), with a L/W ratio of 1.7 (1.3-2.3) and have a Stieda body (SB), Substieda body (SSB), and sporocyst residuum (SR). Oocysts of Eimeria tundraensis n. sp. are spheroidal to subspheroidal, 24.8 x 23.5 microm (23-26 x 22-25 microm), with a L/W ratio of 1.1 (1.0-1.2); these lack a M and OR, but a single PG is present. Sporocysts are elongate ellipsoidal, 15.4 x 8.3 microm (13-17 x 7-9 microm), with a L/W ratio of 1.9 (1.4-2.1) and have a SB, SSB, and SR.

  6. Water quality and communities associated with macrophytes in a shallow water-supply reservoir on an aquaculture farm.

    PubMed

    Sipaúba-Tavares, L H; Dias, S G

    2014-05-01

    Plankton communities and macrofauna associated to aquatic macrophyte stands in a shallow water-supply reservoir (21°14'09″S; 48°18'38″W) on an aquaculture farm were compared to evaluate the relationship between organism densities and some abiotic features of the reservoir. Water and communities associated were sampled at two sites, one in an area with the predominance of Eichhornia azurea (Sw.) Kunth and the other with the predominance of Salvinia auriculata Aublet. Communities associated with macrophytes were sampled with floating quadrants (0.5 m2); the macrophytes were washed and plankton and macrofauna were fixated with 4% formalin and 1% lugol iodine; the specimens were then identified and counted. Plankton and macrofauna communities associated with S. auriculata and E. azurea had a similar diversity of species but different (p<0.05) in the abundance of associated organisms. Eichhornia azurea had the highest contents in dry and wet weight, total phosphorus, total nitrogen and organic matter. Planktonic algae were directly correlated with biomass of E. azurea. The taxa with highest densities were Rotifera and Zygnematophyceae. Results showed that the environmental variables associated with macrophytes presence in the shallow reservoir is a strong predictor of favourable conditions to maintain great diversity plankton community and macrofauna associated with plants. The role of macrophytes is important for not only stabilising the clear-water state and maintaining high diversity of organisms associated, but also it seems to be a good alternative to maintaining desirable water-supply quality for aquaculture farms.

  7. Mortality occurrence and pathogen detection in Crassostrea gigas and Mytilus galloprovincialis close-growing in shallow waters (Goro lagoon, Italy).

    PubMed

    Domeneghetti, Stefania; Varotto, Laura; Civettini, Michele; Rosani, Umberto; Stauder, Monica; Pretto, Tobia; Pezzati, Elisabetta; Arcangeli, Giuseppe; Turolla, Edoardo; Pallavicini, Alberto; Venier, Paola

    2014-11-01

    The complex interactions occurring between farmed bivalves and their potential pathogens in the circumstances of global climate changes are current matter of study, owing to the recurrent production breakdowns reported in Europe and other regions of the world. In the frame of Project FP7-KBBE-2010-4 BIVALIFE, we investigated the occurrence of mortality and potential pathogens during the Spring-Summer transition in Crassostrea gigas and Mytilus galloprovincialis cohabiting in the shallow waters of one northern Italian lagoon (Sacca di Goro, Adriatic Sea) and regarded as susceptible and resistant species, respectively. In 2011, limited bivalve mortality was detected in the open-field trial performed with 6-12 month old spat whereas subsequent trials with 2-3 month old spat produced almost complete (2012) and considerable (2013) oyster mortality. Macroscopical examination and histology excluded the presence of notifiable pathogens but, in the sampling preceding the massive oyster spat mortality of 2012, a μdeleted variant of OsHV-1 DNA was found in wide-ranging amounts in all analyzed oysters in conjunction with substantial levels of Vibrio splendidus and Vibrio aestuarianus. The large oyster spat mortality with borderline OsHV-1 positivity recorded in 2013 supports the multi-factorial etiology of the syndrome. This is the first report of a OsHV-1 (under a form interpreted as the variant μVar) in the Goro lagoon. Transcriptional host footprints are under investigation to better understand the bivalve response to environmental factors, included viral and bacterial pathogens, in relation to the observed mortalities.

  8. Time of day of ovulation by three duck species in subarctic Alaska

    USGS Publications Warehouse

    Esler, Daniel

    1999-01-01

    I examined variation in ovulation times of Northern Pintails (Anas acuta), American Wigeon (A. americana), and Lesser Scaup (Aythya affinis) breeding in subarctic Alaskan wetlands. Ovulation times and, by extension, egg-laying times were highly variable in all three species, with ovulations occurring during all hours of the day. Only Lesser Scaup demonstrated a morning peak in ovulations, within a broad range of ovulation times. Lack of a distinct time of day of ovulation suggests that fitness is not related to egg-laying time for these species, particularly at subarctic latitudes with nearly perpetual daylight. Egg-laying interval may have more adaptive significance than egg-laying time for these species. Ovulation intervals were estimated to be approximately 24 hr, which is short relative to the range of intervals documented in birds, despite high energetic and nutritional costs of egg formation in these species. Evidence of approximately 24-hr ovulation intervals, particularly in the absence of a distinct time of day for egg laying, supports hypotheses that a shortened period of egg production in waterfowl may have selective advantage due to reduction in the period of nest exposure to predation, earlier hatch dates, reduced hatch asynchrony, or improved viability of early-laid eggs.

  9. Devonian-Mississippian carbonate sequence in the Maiyumerak Mountains, western Brooks Range, Alaska

    SciTech Connect

    Dumoulin, J.A. ); Harris, A.G. )

    1990-05-01

    Essentially continuous, dominantly carbonate sedimentation occurred from at least the Early Devonian through the Mississippian in the area that is now the Maiyumerak Mountains, western Brooks Range. This succession is in striking contrast to Paleozoic sequences in the eastern Brooks Range and in the subsurface across northern Alaska, where uppermost Devonian-Mississippian clastic and Carboniferous carbonates unconformably overlie Proterozoic or lower Paleozoic metasedimentary or sedimentary rocks. Conodonts obtained throughout the Maiyumerak Mountains sequence indicate that any hiatus is less than a stage in duration, and there is no apparent physical evidence of unconformity within the succession. The sequence is best exposed northwest of the Eli River, where Emsian-Eifelian dolostones (Baird Group) are conformably overlain by Kinderhookian-Osagian sandy limestones (Utukok Formation) and Osagian-Chesterian fossiliferous limestones (Kogruk Formation) of the Lisburne Group. Conodont species assemblages and sedimentary structures indicate deposition in a range of shallow-water shelf environments. The sequence extends at least 30 km, from the Noatak Quadrangle northeast into the Baird Mountains Quadrangle; its easternmost extent has not been definitively determined. The Ellesmerian orogeny, thought to have produced the extensive middle Paleozoic unconformity seen through much of northern Alaska apparently had little effect on this western Brooks Range sedimentary succession.

  10. Bioavailable metals and cellular effects in the digestive gland of marine limpets living close to shallow water hydrothermal vents.

    PubMed

    Cunha, Luís; Amaral, André; Medeiros, Vera; Martins, Gustavo M; Wallenstein, Francisco F M M; Couto, Ruben P; Neto, Ana I; Rodrigues, Armindo

    2008-04-01

    The pressure exerted by shallow water hydrothermal vents on edible gastropods and their cellular responses triggered by these stresses are almost unknown. The aims of this study were to evaluate the bioavailability of metals in the Macaronesian endemic limpet Patella candei gomesii living close to shallow water hydrothermal vents, and the structural differences in their digestive gland as well as the levels of apoptosis in that organ. Limpets were sampled in four sites, two with the presence of hydrothermalism and the other two without it. Whole body concentrations of several metals (Ca, Cd, Cs, Co, Cu, Fe, Hg, Mg, Mn, Pb, Rb, Se, Sr, and Zn) were obtained, morphometry analysis of the digestive gland and TUNEL test for apoptosis were also performed. Results revealed that the presence of shallow water hydrothermal vents is a source of chronic metal stress to limpets, imposing modifications in the morphometry and cell composition of the digestive gland of those limpets that may constitute cell and tissue adaptations to the environment they live in. This study sets up new baseline data for further research on the influence of shallow water hydrothermal vents over communities living in these habitats.

  11. On the existence of local strong solutions to chemotaxis-shallow water system with large data and vacuum

    NASA Astrophysics Data System (ADS)

    Che, Jiahang; Chen, Li; Duan, Ben; Luo, Zhen

    2016-12-01

    In this paper, motivated by the chemotaxis-Navier-Stokes system arising from mathematical biology [43], a modified shallow water type chemotactic model is derived. For large initial data allowing vacuum, the local existence of strong solutions together with the blow-up criterion is established.

  12. Metagenomic Analysis of Genes Encoding Nutrient Cycling Pathways in the Microbiota of Deep-Sea and Shallow-Water Sponges.

    PubMed

    Li, Zhiyong; Wang, Yuezhu; Li, Jinlong; Liu, Fang; He, Liming; He, Ying; Wang, Shenyue

    2016-12-01

    Sponges host complex symbiotic communities, but to date, the whole picture of the metabolic potential of sponge microbiota remains unclear, particularly the difference between the shallow-water and deep-sea sponge holobionts. In this study, two completely different sponges, shallow-water sponge Theonella swinhoei from the South China Sea and deep-sea sponge Neamphius huxleyi from the Indian Ocean, were selected to compare their whole symbiotic communities and metabolic potential, particularly in element transformation. Phylogenetically diverse bacteria, archaea, fungi, and algae were detected in both shallow-water sponge T. swinhoei and deep-sea sponge N. huxleyi, and different microbial community structures were indicated between these two sponges. Metagenome-based gene abundance analysis indicated that, though the two sponge microbiota have similar core functions, they showed different potential strategies in detailed metabolic processes, e.g., in the transformation and utilization of carbon, nitrogen, phosphorus, and sulfur by corresponding microbial symbionts. This study provides insight into the putative metabolic potentials of the microbiota associated with the shallow-water and deep-sea sponges at the whole community level, extending our knowledge of the sponge microbiota's functions, the association of sponge- microbes, as well as the adaption of sponge microbiota to the marine environment.

  13. A high-resolution finite volume model for shallow water flow on uneven bathymetry using quadrilateral meshes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A two-dimensional cell-centred finite volume model for quadrilateral grids is presented. The solution methodology of the depth-averaged shallow water equations is based upon a Godunov-type upwind finite volume formulation, whereby the inviscid fluxes of the system of equations are obtained using the...

  14. A variational implementation of the implicit particle filter for the shallow water equations

    NASA Astrophysics Data System (ADS)

    Souopgui, I.; Morzfeld, M.; Hussaini, M.; Chorin, A. J.

    2013-12-01

    The estimation of initial conditions for shallow water equations is a well known test problem for operational data assimilation techniques. The state-of-the-art approach to this problem is the variational method (4D-Var), i.e. the computation of the mode of the posterior probability density function (pdf) via the adjoint technique. We add a sampling step to the variational method, thus turning a computation of the conditional mode (a biased estimator) into a computation of the conditional mean (the minimum least square error estimator). Our implementation relies on implicit sampling, which is a Monte Carlo (MC) sampling scheme. The idea in implicit sampling is to first search for the high-probability region of the posterior pdf and then to find samples in this region. Because the samples are concentrated in the high-probability region, fewer samples are required than with competing MC schemes and, thus, implicit sampling can be more efficient than other MC schemes. The search for the high-probability region can be done via a numerical minimization that is very similar to the minimization in 4D-Var. Here, we use existing 4D-Var code to implement the implicit sampling scheme. Once the minimization problem is solved, we obtain samples by solving algebraic equations with a random right-hand-side. These equations can be solved efficiently, so that the additional cost of our approach, compared to 4D-Var, is small. We present numerical experiments to demonstrate the applicability and efficiency of our approach. These numerical experiments mimic physical experiments done with the CORIOLIS turntable in Grenoble (France), which are used to study the drift of a vortex. In particular we consider shallow water equations on a square domain (2.5m x 2.5m) with open boundary conditions and discretize the equations with finite differences on a staggered grid of size 256 x 256 and a fourth order Runge-Kutta time integrator. Our goal is to estimate the initial state (velocities and

  15. Shallow Water Euxinia and Density Stratification of the Cenomanian/Turonian Western Interior Seaway in Texas

    NASA Astrophysics Data System (ADS)

    Wehner, M.; Pope, M. C.; Tice, M. M.; Gardner, R.; Donovan, A. D.; Staerker, S.; Lyon, T.; Maulana, I.; Pramudito, A.; Xu, G.; Zeng, Z.

    2014-12-01

    The Eagle Ford Group was deposited at the south and east side of the Western Interior Seaway (WIS). These sediments contain evidence of anoxia and shallow-water deposition (between storm-wave and fair weather wave-base) in the proximal deposits at Lozier Canyon and Antonio Creek (LC/AC). Shallow-water (above storm wave-base) depositional conditions are mostly based on the suite of primary sedimentary structures that includes: hummocky cross-stratification (HCS), swaley cross-stratification (SCS), symmetric ripples, gutter casts and shell lags. These occur in outcrop and support the interpretation that LC/AC is the most proximal location relative to other study locations. At Hot Springs in Brewster County, Texas, sedimentary structures are limited to shell lags, a few symmetric ripples and low-angle laminations. This is consistent with the distal expression of storm deposits. The primary sedimentary structures from the core from the subsurface in McMullen County, south Texas, are limited to those of low-energy currents, scouring, and reworking, which could indicate it is in the distally steepened portion of the carbonate ramp on which Eagle Ford Groups are deposited. Pelagic foraminifera are the most microfossil and benthic foraminifera only occur in the Upper Eagle Formation at LC/AC. Molybdenum was also used as a proxy for occurrence and persistence of a sulfer-reducing zone. The geochemical data from the subsurface core suggests persistence of anoxia throughout its depositional history. At LC/AC, molybdenum is elevated (up to 5-6 times average shale value) and bioturbation in these zones is limited to the surfaces of symmetric ripples, suggesting that oxygenation events were brief and occurred only immediately after storm events. This is consistent with the hypothesis that the HCS, SCS, and symmetric ripples were caused by storms and temporarily mixed the ocean in a normally stratified water column. At LC/AC, the water column became persistently oxic from the

  16. Dynamic drivers of a shallow-water hydrothermal vent ecogeochemical system (Milos, Eastern Mediterranean)

    NASA Astrophysics Data System (ADS)

    Yücel, Mustafa; Sievert, Stefan; Giovanelli, Donato; Foustoukos, Dionysis; DeForce, Emelia; Thomas, François; Vetriani, Constantino; Le Bris, Nadine

    2014-05-01

    Shallow-water hydrothermal vents share many characteristics with their deep-sea analogs. However, despite ease of access, much less is known about the dynamics of these systems. Here, we report on the spatial and temporal chemical variability of a shallow-water vent system at Paleochori Bay, Milos Island, Greece, and on the bacterial and archaeal diversity of associated sandy sediments. Our multi-analyte voltammetric profiles of dissolved O2 and hydrothermal tracers (e.g. Fe2+, FeSaq, Mn2+) on sediment cores taken along a transect in hydrothermally affected sediments indicate three different areas: the central vent area (highest temperature) with a deeper penetration of oxygen into the sediment, and a lack of dissolved Fe2+ and Mn2+; a middle area (0.5 m away) rich in dissolved Fe2+ and Mn2+ (exceeding 2 mM) and high free sulfide with potential for microbial sulfide oxidation as suggested by the presence of white mats at the sediment surface; and, finally, an outer rim area (1-1.5 m away) with lower concentrations of Fe2+ and Mn2+ and higher signals of FeSaq, indicating an aged hydrothermal fluid contribution. In addition, high-frequency temperature series and continuous in situ H2S measurements with voltammetric sensors over a 6-day time period at a distance 0.5 m away from the vent center showed substantial temporal variability in temperature (32 to 46 ºC ) and total sulfide (488 to 1329 µM) in the upper sediment layer. Analysis of these data suggests that tides, winds, and abrupt geodynamic events generate intermittent mixing conditions lasting for several hours to days. Despite substantial variability, the concentration of sulfide available for chemoautotrophic microbes remained high. These findings are consistent with the predominance of Epsilonproteobacteria in the hydrothermally influenced sediments Diversity and metagenomic analyses on sediments and biofilm collected along a transect from the center to the outer rim of the vent provide further insights on

  17. Shallow water mud-mounds of the Early Devonian Buchan Group, East Gippsland, Australia

    NASA Astrophysics Data System (ADS)

    Tosolini, A.-M. P.; Wallace, M. W.; Gallagher, S. J.

    2012-12-01

    The Lower Devonian Rocky Camp Member of the Murrindal Limestone, Buchan Group of southeastern Australia consists of a series of carbonate mud-mounds and smaller lagoonal bioherms. The Rocky Camp mound is the best exposed of the mud-mounds and has many characteristics in common with Waulsortian (Carboniferous) mounds. Detailed paleoecological and sedimentological studies indicate that the mound initially accumulated in the photic zone, in contrast to most of the previously recorded mud-mounds. Five facies are present in the mud-mound: a Dasycladacean Wackestone Facies at the base of the mound represents a moderate energy, shallow water bank environment within the photic zone. A Crinioidal Wackestone Facies was deposited in a laterally equivalent foreslope setting. A Poriferan-Crinoidal Mudstone Facies developed in a quiet, deeper water, lee-side mound setting associated with a minor relative sea-level rise. A Stromatoporoid-Coralline Packstone Facies in the upper part of the mound deposited in a high-energy, fair-weather wave base, mound-front environment. The crest of the mound is represented by a Crinoidal-Receptaculitid Packstone Facies indicative of a moderate-energy mound-top environment in the photic zone, sheltered by the mound-front stromatoporoid-coral communities. A mound flank facies is present on the southern side of the mound and this consists of high-energy crinoidal grainstones. Mud-mound deposition was terminated by a transgression that deposited dark gray, fossil-poor marl of the overlying Taravale Formation. The Rocky Camp mound appears to have originated in shallow water photic zone conditions and grew into a high-energy environment, with the mound being eventually colonized by corals and stromatoporoids. The indications of a high-energy environment during later mound growth (growth form of colonial metazoans and grainstones of the flanking facies) suggest that the micrite in the mound was autochthonous and implies the presence of an energy

  18. Shallow water sediment properties derived from high-frequency shear and interface waves

    NASA Astrophysics Data System (ADS)

    Ewing, John; Carter, Jerry A.; Sutton, George H.; Barstow, Noel

    1992-04-01

    Low-frequency sound propagation in shallow water environments is not restricted to the water column but also involves the subbottom. Thus, as well as being important for geophysical description of the seabed, subbottom velocity/attenuation structure is essential input for predictive propagation models. To estimate this structure, bottom-mounted sources and receivers were used to make measurements of shear and compressional wave propagation in shallow water sediments of the continental shelf, usually where boreholes and high-resolution reflection profiles give substantial supporting geologic information about the subsurface. This colocation provides an opportunity to compare seismically determined estimates of physical properties of the seabed with the "ground truth" properties. Measurements were made in 1986 with source/detector offsets up to 200 m producing shear wave velocity versus depth profiles of the upper 30-50 m of the seabed (and P wave profiles to lesser depths). Measurements in 1988 were made with smaller source devices designed to emphasize higher frequencies and recorded by an array of 30 sensors spaced at 1-m intervals to improve spatial sampling and resolution of shallow structure. These investigations with shear waves have shown that significant lateral and vertical variations in the physical properties of the shallow seabed are common and are principally created by erosional and depositional processes associated with glacial cycles and sea level oscillations during the Quaternary. When the seabed structure is relatively uniform over the length of the profiles, the shear wave fields are well ordered, and the matching of the data with full waveform synthetics has been successful, producing velocity/attenuation models consistent with the subsurface lithology indicated by coring results. Both body waves and interface waves have been modeled for velocity/attenuation as a function of depth with the aid of synthetic seismograms and other analytical

  19. Formation Conditions and Sedimentary Characteristics of a Triassic Shallow Water Braided Delta in the Yanchang Formation, Southwest Ordos Basin, China

    PubMed Central

    Liu, Ziliang; Shen, Fang; Zhu, Xiaomin; Li, Fengjie; Tan, Mengqi

    2015-01-01

    A large, shallow braided river delta sedimentary system developed in the Yanchang Formation during the Triassic in the southwest of the Ordos basin. In this braided delta system, abundant oil and gas resources have been observed, and the area is a hotspot for oil and gas resource exploration. Through extensive field work on outcrops and cores and analyses of geophysical data, it was determined that developments in the Late Triassic produced favorable geological conditions for the development of shallow water braided river deltas. Such conditions included a large basin, flat terrain, and wide and shallow water areas; wet and dry cyclical climate changes; ancient water turbulence; dramatic depth cycle changes; ancient uplift development; strong weathering of parent rock; and abundant supply. The shallow water braided river delta showed grain sediment granularity, plastic debris, and sediment with mature composition and structure that reflected the strong hydrodynamic environment of large tabular cross-bedding, wedge cross-bedding, and multiple positive rhythms superimposed to form a thick sand body layer. The branch river bifurcation developed underwater, and the thickness of the sand body increased further, indicating that the slope was slow and located in shallow water. The seismic responses of the braided river delta reflected strong shallow water performance, indicated by a progradation seismic reflection phase axis that was relatively flat; in addition, the seismic reflection amplitude was strong and continuous with a low angle and extended over considerable distances (up to 50 km). The sedimentary center was close to the provenance, the width of the river was large, and a shallow sedimentary structure and a sedimentary rhythm were developed. The development of the delta was primarily controlled by tectonic activity and changes in the lake level; as a result, the river delta sedimentary system eventually presented a “small plain, big front” character. PMID

  20. Seafloor bathymetry in deep and shallow water marine CSEM responses of Nigerian Niger Delta oil field: Effects and corrections

    NASA Astrophysics Data System (ADS)

    Folorunso, Adetayo Femi; Li, Yuguo

    2015-12-01

    Topography distortions in bathymetrically acquired marine Controlled-Source Electromagnetic (mCSEM) responses are capable of misleading interpretation to the presence or absence of the target if not corrected for. For this reason, the effects and correction of bathymetry distortions on the deep and shallow seafloor mCSEM responses of the Niger Delta Oil province were examined in this paper. Marine CSEM response of the Niger Delta geological structure was modelled by using a 2.5D adaptive finite element forward modelling code. In both the deep water and shallow water cases, the bathymetry distortions in the electric field amplitude and phase were found to get smaller with increasing Tx-Rx offsets and contain short-wavelength components in the amplitude curves which persist at all Tx-Rx offsets. In the deep water, topographic effects on the reservoir signatures are not significant, but as water depth reduces, bathymetric distortions become more significant as a result of the airwave effects, masking the target signatures. The correction technique produces a good agreement between the flat-seafloor reservoir model and its equivalent bathymetric model in deep water at 0.25 Hz, while in shallow water, the corrected response only shows good agreement at shorter offsets but becomes complicated at longer offsets due to airwave effects. Transmission frequency was extended above and below 0.25 Hz in the frequency spectrum and the correction method applied. The bathymetry correction at higher frequency (1.75 Hz) is not effective in removing the topographic effects in either deep or shallow water. At 0.05 Hz for both seafloor scenarios, we obtained the best corrected amplitude profiles, removing completely the distortions from both topographic undulation and airwave effects in the shallow water model. Overall, the work shows that the correction technique is effective in reducing bathymetric effects in deep water at medium frequency and in both deep and shallow waters at a low

  1. Formation Conditions and Sedimentary Characteristics of a Triassic Shallow Water Braided Delta in the Yanchang Formation, Southwest Ordos Basin, China.

    PubMed

    Liu, Ziliang; Shen, Fang; Zhu, Xiaomin; Li, Fengjie; Tan, Mengqi

    2015-01-01

    A large, shallow braided river delta sedimentary system developed in the Yanchang Formation during the Triassic in the southwest of the Ordos basin. In this braided delta system, abundant oil and gas resources have been observed, and the area is a hotspot for oil and gas resource exploration. Through extensive field work on outcrops and cores and analyses of geophysical data, it was determined that developments in the Late Triassic produced favorable geological conditions for the development of shallow water braided river deltas. Such conditions included a large basin, flat terrain, and wide and shallow water areas; wet and dry cyclical climate changes; ancient water turbulence; dramatic depth cycle changes; ancient uplift development; strong weathering of parent rock; and abundant supply. The shallow water braided river delta showed grain sediment granularity, plastic debris, and sediment with mature composition and structure that reflected the strong hydrodynamic environment of large tabular cross-bedding, wedge cross-bedding, and multiple positive rhythms superimposed to form a thick sand body layer. The branch river bifurcation developed underwater, and the thickness of the sand body increased further, indicating that the slope was slow and located in shallow water. The seismic responses of the braided river delta reflected strong shallow water performance, indicated by a progradation seismic reflection phase axis that was relatively flat; in addition, the seismic reflection amplitude was strong and continuous with a low angle and extended over considerable distances (up to 50 km). The sedimentary center was close to the provenance, the width of the river was large, and a shallow sedimentary structure and a sedimentary rhythm were developed. The development of the delta was primarily controlled by tectonic activity and changes in the lake level; as a result, the river delta sedimentary system eventually presented a "small plain, big front" character.

  2. Shallow water sea slugs (Gastropoda: Heterobranchia) from the northwestern coast of the Sea of Japan, north of Peter the Great Bay, Russia

    PubMed Central

    2016-01-01

    The coast of northern Primorye region, north of Peter the Great Bay has been sparsely studied in regards to its molluscan fauna, with just a few works reviewing the distribution of local mollusks. This work presents a survey of the shallow water heterobranch sea slugs currently occurring around Kievka Bay to Oprichnik Bay, Russia. Thirty-nine species of sea slugs were found in this study and the new species Cadlina olgae sp. nov., described herein. Most (24) of the species occurring in the area have widespread ranges in the northern Pacific Ocean. The eight species are endemic for the Sea of Japan and adjacent part of the Sea of Okhotsk. Seven other occur also in northern Atlantic and Arctic waters. Thirteen found species are not known from Peter the Great Bay but known from adjacent northern Pacific waters. The finding of a previously undescribed species emphasizes the need of further surveys, particularly in subtidal and deeper waters, in order to improve the knowledge on this neglected fauna in Primorye. PMID:27957399

  3. An investigation into environment dependent nanomechanical properties of shallow water shrimp (Pandalus platyceros) exoskeleton.

    PubMed

    Verma, Devendra; Tomar, Vikas

    2014-11-01

    The present investigation focuses on understanding the influence of change from wet to dry environment on nanomechanical properties of shallow water shrimp exoskeleton. Scanning Electron Microscopy (SEM) based measurements suggest that the shrimp exoskeleton has Bouligand structure, a key characteristic of the crustaceans. As expected, wet samples are found to be softer than dry samples. Reduced modulus values of dry samples are found to be 24.90 ± 1.14 GPa as compared to the corresponding values of 3.79 ± 0.69 GPa in the case of wet samples. Hardness values are found to be 0.86 ± 0.06 GPa in the case of dry samples as compared to the corresponding values of 0.17 ± 0.02 GPa in the case of wet samples. In order to simulate the influence of underwater pressure on the exoskeleton strength, constant load creep experiments as a function of wet and dry environments are performed. The switch in deformation mechanism as a function of environment is explained based on the role played by water molecules in assisting interface slip and increased ductility of matrix material in wet environment in comparison to the dry environment.

  4. A well-balanced scheme for the shallow-water equations with topography or Manning friction

    NASA Astrophysics Data System (ADS)

    Michel-Dansac, Victor; Berthon, Christophe; Clain, Stéphane; Foucher, Françoise

    2017-04-01

    We consider the shallow-water equations with Manning friction or topography, as well as a combination of both these source terms. The main purpose of this work concerns the derivation of a non-negativity preserving and well-balanced scheme that approximates solutions of the system and preserves the associated steady states, including the moving ones. In addition, the scheme has to deal with vanishing water heights and transitions between wet and dry areas. To address such issues, a particular attention is paid to the study of the steady states related to the friction source term. Then, a Godunov-type scheme is obtained by using a relevant average of the source terms in order to enforce the required well-balance property. An implicit treatment of both topography and friction source terms is also exhibited to improve the scheme while dealing with vanishing water heights. A second-order well-balanced MUSCL extension is designed, as well as an extension for the two-dimensional case. Numerical experiments are performed in order to highlight the properties of the scheme.

  5. Vertical amplitude phase structure of a low-frequency acoustic field in shallow water

    NASA Astrophysics Data System (ADS)

    Kuznetsov, G. N.; Lebedev, O. V.; Stepanov, A. N.

    2016-11-01

    We obtain in integral and analytic form the relations for calculating the amplitude and phase characteristics of an interference structure of orthogonal projections of the oscillation velocity vector in shallow water. For different frequencies and receiver depths, we numerically study the source depth dependences of the effective phase velocities of an equivalent plane wave, the orthogonal projections of the sound pressure phase gradient, and the projections of the oscillation velocity vector. We establish that at low frequencies in zones of interference maxima, independently of source depth, weakly varying effective phase velocity values are observed, which exceed the sound velocity in water by 5-12%. We show that the angles of arrival of the equivalent plane wave and the oscillation velocity vector in the general case differ; however, they virtually coincide in the zone of the interference maximum of the sound pressure under the condition that the horizontal projections of the oscillation velocity appreciably exceed the value of the vertical projection. We give recommendations on using the sound field characteristics in zones with maximum values for solving rangefinding and signal-detection problems.

  6. Shallow water processes govern system-wide phytoplankton bloom dynamics: A modeling study

    USGS Publications Warehouse

    Lucas, L.V.; Koseff, Jeffrey R.; Monismith, Stephen G.; Thompson, J.K.

    2009-01-01

    A pseudo-two-dimensional numerical model of estuarine phytoplankton growth and consumption, vertical turbulent mixing, and idealized cross-estuary transport was developed and applied to South San Francisco Bay. This estuary has two bathymetrically distinct habitat types (deep channel, shallow shoal) and associated differences in local net rates of phytoplankton growth and consumption, as well as differences in the water column's tendency to stratify. Because many physical and biological time scales relevant to algal population dynamics decrease with decreasing depth, process rates can be especially fast in the shallow water. We used the model to explore the potential significance of hydrodynamic connectivity between a channel and shoal and whether lateral transport can allow physical or biological processes (e.g. stratification, benthic grazing, light attenuation) in one sub-region to control phytoplankton biomass and bloom development in the adjacent sub-region. Model results for South San Francisco Bay suggest that lateral transport from a productive shoal can result in phytoplankton biomass accumulation in an adjacent deep, unproductive channel. The model further suggests that turbidity and benthic grazing in the shoal can control the occurrence of a bloom system-wide; whereas, turbidity, benthic grazing, and vertical density stratification in the channel are likely to only control local bloom occurrence or modify system-wide bloom magnitude. Measurements from a related field program are generally consistent with model-derived conclusions. ?? 2008 Elsevier B.V.

  7. Results of an experiment using AUVs for shallow-water mine reconnaissance

    NASA Astrophysics Data System (ADS)

    Smith, Samuel M.; An, Edgar; Christensen, Reed; Kloske, John; Snowden, Scott; Kronen, David; Marquis, Larry

    1999-07-01

    As part of the South Florida Ocean Measurement Center in Ft. Lauderdale Florida, a shallow water range with mines has been set up for a series of MCM experiments using the FAU AUVs. The first experiment was conducted December of 1998. The planned objective was to quantify the performance of the Ocean Explorer AUV for mine reconnaissance tasks such as rapid environmental assessment, remote search, remote classification and remote identification of mine like objects both moored in the water column and laying on the sea floor. The primary sensors used for this test were high frequency side scan and ambient light video. In addition, a forward look sonar and a laser line scanner were fielded. A CTD and DVL/ADCP provide environmental data. The AUV first conducted a wide area side scan survey and environmental assessment. The AUV then returned and its data uploaded. Human operators post processed the side scan and manually detected and classified targets. The AUV was then programmed to revisit the targets and perform close in multiple sensor sweeps with side scan and video of each target. Manual post processing and analysis of this data proved sufficient information for more accurate classification and even identification of targets. This paper will present preliminary results of this experiment with likely implications to VSW MCM operations.

  8. Integrating Sensors into a Marine Drone for Bathymetric 3D Surveys in Shallow Waters.

    PubMed

    Giordano, Francesco; Mattei, Gaia; Parente, Claudio; Peluso, Francesco; Santamaria, Raffaele

    2015-12-29

    This paper demonstrates that accurate data concerning bathymetry as well as environmental conditions in shallow waters can be acquired using sensors that are integrated into the same marine vehicle. An open prototype of an unmanned surface vessel (USV) named MicroVeGA is described. The focus is on the main instruments installed on-board: a differential Global Position System (GPS) system and single beam echo sounder; inertial platform for attitude control; ultrasound obstacle-detection system with temperature control system; emerged and submerged video acquisition system. The results of two cases study are presented, both concerning areas (Sorrento Marina Grande and Marechiaro Harbour, both in the Gulf of Naples) characterized by a coastal physiography that impedes the execution of a bathymetric survey with traditional boats. In addition, those areas are critical because of the presence of submerged archaeological remains that produce rapid changes in depth values. The experiments confirm that the integration of the sensors improves the instruments' performance and survey accuracy.

  9. A new multichannel spatial diversity technique for long-range acoustic communications in shallow water

    NASA Astrophysics Data System (ADS)

    Beaujean, Pierre-Philippe J.; Bernault, Emmanuel P.

    2002-11-01

    A new multichannel spatial diversity technique has been developed for underwater acoustic communications in very shallow waters. This technique combines a novel synchronization method with maximum-likelihood symbol estimation. It was tested with a multichannel Mills-Cross receiver using various numbers of elements. The FAU general purpose acoustic modem source transmitted messages using four types of frequency-hopped multiple-frequency-chirp-keying (FH-MFSK) modulation: 4 hops at 221 coded bits per second (cps), 2 hops at 442 cps, or no hopping at 1172 cps. These types of modulation allowed for robust data transmission in adverse environment. The modem operated between 16 and 32 kHz at 192-dB source level, at ranges from 1 to 5 km in 40 ft of water. Using only four channels of the Mills-Cross receiver array, messages coded at 1172 cps were received with a frame error rate (FER) of 0% at a range of 3 km. In the same four-channel configuration, messages coded at 221 cps were received with no frame error at 5 km. The experimental results matched the performance predictions from the Crepeaus model. This reliable and computation-efficient method can be implemented on new generations of embedded acoustic modems, such as the four-channel FAU acoustic modem, and can provide significant improvements in communication performance.

  10. Localization of nonlinear shallow water waves over a randomly rough seabed

    NASA Astrophysics Data System (ADS)

    Mei, Chiang; Grataloup, Geraldine; Li, Yile

    2003-11-01

    Localization or spatial attenuation of sea waves can be caused by bottom friction and by radiation of scattered waves. We describe a theory of shallow-water waves scattered by a long stretch of randomly rough seabed, where the root-mean-square height of the roughness is moderately small. Boussinesq equations are used as the starting point. By using two-scale expansions and Green's functions, multiple scattering by the rough bottom and the nonlinear exchanges of energy between different frequencies are accounted for. For monochromatic incident waves, the evolution equations for all harmonics are shown to be nonlinearly coupled ordinary differential equations with damping, whose coefficients are related to the correlation functions of the roughess. Examples of localization and generation of harmonics are shown by numerical examples. For an incident soliton, the evolution equation is shown to be a KdV-Burgers equation with new diffusion and dispersion terms in integral form, implying memory. Numerical results on soliton deformation, fission and localization will be discussed. Long fetch approximation will be described. This theory differs from several existing ones where random potentials are added to the evolution equations.

  11. Positivity-preserving high order well-balanced discontinuous Galerkin methods for the shallow water equations

    SciTech Connect

    Xing, Yulong; Zhang, Xiangxiong; Shu, Chi-wang

    2010-01-01

    Shallow water equations with a non-flat bottom topography have been widely used to model flows in rivers and coastal areas. An important difficulty arising in these simulations is the appearance of dry areas where no water is present, as standard numerical methods may fail in the presence of these areas. These equations also have still water steady state solutions in which the flux gradients are nonzero but exactly balanced by the source term. In this paper we propose a high order discontinuous Galerkin method which can maintain the still water steady state exactly, and at the same time can preserve the non-negativity of the water height without loss of mass conservation. A simple positivity-preserving limiter, valid under suitable CFL condition, will be introduced in one dimension and then extended to two dimensions with rectangular meshes. Numerical tests are performed to verify the positivity-preserving property, well-balanced property, high order accuracy, and good resolution for smooth and discontinuous solutions.

  12. Balanced Central Schemes for the Shallow Water Equations on Unstructured Grids

    NASA Technical Reports Server (NTRS)

    Bryson, Steve; Levy, Doron

    2004-01-01

    We present a two-dimensional, well-balanced, central-upwind scheme for approximating solutions of the shallow water equations in the presence of a stationary bottom topography on triangular meshes. Our starting point is the recent central scheme of Kurganov and Petrova (KP) for approximating solutions of conservation laws on triangular meshes. In order to extend this scheme from systems of conservation laws to systems of balance laws one has to find an appropriate discretization of the source terms. We first show that for general triangulations there is no discretization of the source terms that corresponds to a well-balanced form of the KP scheme. We then derive a new variant of a central scheme that can be balanced on triangular meshes. We note in passing that it is straightforward to extend the KP scheme to general unstructured conformal meshes. This extension allows us to recover our previous well-balanced scheme on Cartesian grids. We conclude with several simulations, verifying the second-order accuracy of our scheme as well as its well-balanced properties.

  13. A middle Devonian temperate water limestone-isotopes, stromatoporoids and shallow water facies

    SciTech Connect

    Wolosz, T.H.

    1995-09-01

    The Edgecliff Member of the Middle Devonian Onondaga Formation has long been of interest to exploration geologists because its pinnacle reefs and bioherms are potential natural gas reservoirs. Current evidence indicates that the Edgecliff was deposited in a shallow, temperate water environment suggesting that application of standard tropical carbonate models will be misleading. Three lines of evidence support the temperate water model for the Edgecliff. Carbon and oxygen isotopic analyses performed on 29 samples from the non-luminescent portions of 15 brachiopods with prismatic ultrastructure yield {delta}{sup 18}O values which are isotopically heavier than accepted values for Devonian sea-water, suggesting cool water conditions. The distribution of stromatoporoids (assumed warm water organisms) ranges from rare and small in the eastern part of New York State, to more common in Ontario, Canada. This trend in stromatoporoids appears to represent an increase in size and abundance as the distance from the paleo-equator decreases. Finally, previously unrecognized shallow water facies in the Edgecliff including thin, dolomitized and bioturbated carbonate muds, solitary rugosan biostromes and ridge-like fringing coral bioherms negate any possibility that the isotopic and paleobiologic data reflect deposition in deep, cooler waters as opposed to an overall temperate water environment.

  14. Conservative numerical simulation of multi-component transport in two-dimensional unsteady shallow water flow

    NASA Astrophysics Data System (ADS)

    Murillo, J.; García-Navarro, P.; Burguete, J.

    2009-08-01

    An explicit finite volume model to simulate two-dimensional shallow water flow with multi-component transport is presented. The governing system of coupled conservation laws demands numerical techniques to avoid unrealistic values of the transported scalars that cannot be avoided by decreasing the size of the time step. The presence of non conservative products such as bed slope and friction terms, and other source terms like diffusion and reaction, can make necessary the reduction of the time step given by the Courant number. A suitable flux difference redistribution that prevents instability and ensures conservation at all times is used to deal with the non-conservative terms and becomes necessary in cases of transient boundaries over dry bed. The resulting method belongs to the category of well-balanced Roe schemes and is able to handle steady cases with flow in motion. Test cases with exact solution, including transient boundaries, bed slope, friction, and reaction terms are used to validate the numerical scheme. Laboratory experiments are used to validate the techniques when dealing with complex systems as the κ-ɛ model. The results of the proposed numerical schemes are compared with the ones obtained when using uncoupled formulations.

  15. A well-balanced numerical scheme for shallow water simulation on adaptive grids

    NASA Astrophysics Data System (ADS)

    Zhang, H. J.; Zhou, J. Z.; Bi, S.; Li, Q. Q.; Fan, Y.

    2014-04-01

    The efficiency of solving two-dimensional shallow-water equations (SWEs) is vital for simulation of large-scale flood inundation. For flood flows over real topography, local high-resolution method, which uses adaptable grids, is required in order to prevent the loss of accuracy of the flow pattern while saving computational cost. This paper introduces an adaptive grid model, which uses an adaptive criterion calculated on the basis of the water lever. The grid adaption is performed by manipulating subdivision levels of the computation grids. As the flow feature varies during the shallow wave propagation, the local grid density changes adaptively and the stored information of neighbor relationship updates correspondingly, achieving a balance between the model accuracy and running efficiency. In this work, a well-balanced (WB) scheme for solving SWEs is introduced. In reconstructions of Riemann state, the definition of the unique bottom elevation on grid interfaces is modified, and the numerical scheme is pre-balanced automatically. By the validation against two idealist test cases, the proposed model is applied to simulate flood inundation due to a dam-break of Zhanghe Reservoir, Hubei province, China. The results show that the presented model is robust and well-balanced, has nice computational efficiency and numerical stability, and thus has bright application prospects.

  16. Snorkelling and trampling in shallow-water fringing reefs: risk assessment and proposed management strategy.

    PubMed

    Hannak, Judith S; Kompatscher, Sarah; Stachowitsch, Michael; Herler, Jürgen

    2011-10-01

    Shallow reefs (reef flats <1.5 m) in the northern Red Sea are impacted by growing tourism that includes swimmers, snorkellers and reef walkers but have largely been neglected in past studies. We selected a fringing reef along the lagoon of Dahab (Sinai, Egypt) as a model for a management strategy. Point-intercept line transects were used to determine substrate composition, coral community and condition, and the coral damage index (CDI) was applied. Approximately 84% of the coral colonies showed signs of damage such as breakage, partial mortality or algal overgrowth, especially affecting the most frequent coral genus Acropora. Questionnaires were used to determine the visitors' socio-economic background and personal attitudes regarding snorkelling, SCUBA-diving and interest in visiting a prospective snorkelling trail. Experiencing nature (97%) was by far the strongest motivation, and interest in further education about reef ecology and skill training was high. Less experienced snorkellers and divers--the target group for further education and skill training--were those most prepared to financially support such a trail. We therefore recommend a guided underwater snorkelling trail and restricting recreational use to a less sensitive 'ecotourism zone' while protecting the shallow reef flat. Artificial structures can complete the trail and offer the opportunity to snorkel over deeper areas at unfavourable tide or wind conditions. This approach provides a strategy for the management and conservation of shallow-water reefs, which are facing increasing human impact here and elsewhere.

  17. Geoacoustic inversion with two source-receiver arrays in shallow water.

    PubMed

    Sukhovich, Alexey; Roux, Philippe; Wathelet, Marc

    2010-08-01

    A geoacoustic inversion scheme based on a double beamforming algorithm in shallow water is proposed and tested. Double beamforming allows identification of multi-reverberated eigenrays propagating between two vertical transducer arrays according to their emission and reception angles and arrival times. Analysis of eigenray intensities yields the bottom reflection coefficient as a function of angle of incidence. By fitting the experimental reflection coefficient with a theoretical prediction, values of the acoustic parameters of the waveguide bottom can be extracted. The procedure was initially tested in a small-scale tank experiment for a waveguide with a Plexiglas bottom. Inversion results for the speed of shear waves in Plexiglas are in good agreement with the table values. A similar analysis was applied to data collected during an at-sea experiment in shallow coastal waters of the Mediterranean. Bottom reflection coefficient was fitted with the theory in which bottom sediments are modeled as a multi-layered system. Retrieved bottom parameters are in quantitative agreement with those determined from a prior inversion scheme performed in the same area. The present study confirms the interest in processing source-receiver array data through the double beamforming algorithm, and indicates the potential for application of eigenray intensity analysis to geoacoustic inversion problems.

  18. Marine Electromagnetic System Development in the Shallow Water Environment for Radioactive Waste Repository Site Investigation

    NASA Astrophysics Data System (ADS)

    Yoshimura, K.; Sakashita, S.; Okubo, S.; Yamane, K.

    2006-12-01

    Radioactive Waste Management Funding and Research Center of Japan has recently conducted a program to develop an electromagnetic (EM) technology for investigating the subsurface to the depths of 1,000m below the seafloor in the near-shore environment. Potential applications include structural studies for geological disposal of radioactive wastes. The system includes both natural field by magnetotellurics and controlled source EM data was collected to evaluate the feasibility of the methods and instrumentation. The shallow water environment is challenging because of high water currents and wave motion effects contaminating the data. We demonstrate the performance test of the new type of instrument, and the field experiment that was carried out in the Monterey Bay of California, USA, in 2003 and 2004. In this paper we describe the instrumentation developed, shows some examples from field trial and finally provide some inversion results using collected and simulated data. The system consists of EM transmitter deployed on the beach in combination with a series of offshore based multicomponent receivers. Field data collected near Monterey California revealed some of the challenges associated with this type of system. Collected data showed the influence of wave and cultural noise as well. In site of these difficulties we were able to accumulate a sufficient quantity of good quality records to interpret results. We show 2-D inversion results which image the "Navy Fault zone" which strikes NW-SE offshore Monterey bay in water depths of 10 to 40m.

  19. Energy distribution in shallow water ship wakes from a spectral analysis of the wave field

    NASA Astrophysics Data System (ADS)

    Caplier, Clément; Rousseaux, Germain; Calluaud, Damien; David, Laurent

    2016-10-01

    This work presents an experimental study of the effects of finite water depth on the waves generated by a ship in a towing tank. The wakes of two hull forms representative of maritime and river ships are measured for both deep water and shallow water configurations and for several Froude numbers. The free surface deformations are measured with an optical stereo-correlation measurement method to access a full and detailed reconstruction of the wave fields. The spatial resolution of the reconstructed wakes allows us to perform a spectral analysis of the waves generated by the ships and to decompose them into a near-field hydrodynamic response and a far-field undulatory component. First, the spectral analysis method is presented and the effects of finite water depth on a theoretical point of view are studied. The analysis of subcritical, trans-critical, and supercritical ship wakes in both real space and spectral space highlights the effects of the finite water depth, of the ship speed, and of the hull shape on the energy distribution in the ship wakes through these different regimes.

  20. Modelling rapid mass movements using the shallow water equations in Cartesian coordinates

    NASA Astrophysics Data System (ADS)

    Hergarten, S.; Robl, J.

    2015-03-01

    We propose a new method to model rapid mass movements on complex topography using the shallow water equations in Cartesian coordinates. These equations are the widely used standard approximation for the flow of water in rivers and shallow lakes, but the main prerequisite for their application - an almost horizontal fluid table - is in general not satisfied for avalanches and debris flows in steep terrain. Therefore, we have developed appropriate correction terms for large topographic gradients. In this study we present the mathematical formulation of these correction terms and their implementation in the open-source flow solver GERRIS. This novel approach is evaluated by simulating avalanches on synthetic and finally natural topographies and the widely used Voellmy flow resistance law. Testing the results against analytical solutions and the proprietary avalanche model RAMMS, we found a very good agreement. As the GERRIS flow solver is freely available and open source, it can be easily extended by additional fluid models or source areas, making this model suitable for simulating several types of rapid mass movements. It therefore provides a valuable tool for assisting regional-scale natural hazard studies.

  1. On the feasibility of the use of wind SAR to downscale waves on shallow water

    NASA Astrophysics Data System (ADS)

    Gutiérrez, O. Q.; Filipponi, F.; Taramelli, A.; Valentini, E.; Camus, P.; Méndez, F. J.

    2016-01-01

    In recent years, wave reanalyses have become popular as a powerful source of information for wave climate research and engineering applications. These wave reanalyses provide continuous time series of offshore wave parameters; nevertheless, in coastal areas or shallow water, waves are poorly described because spatial resolution is not detailed. By means of wave downscaling, it is possible to increase spatial resolution in high temporal coverage simulations, using forcing from wind and offshore wave databases. Meanwhile, the reanalysis wave databases are enough to describe the wave climate at the limit of simulations; wind reanalyses at an adequate spatial resolution to describe the wind structure near the coast are not frequently available. Remote sensing synthetic aperture radar (SAR) has the ability to detect sea surface signatures and estimate wind fields at high resolution (up to 300 m) and high frequency. In this work a wave downscaling is done on the northern Adriatic Sea, using a hybrid methodology and global wave and wind reanalysis as forcing. The wave fields produced were compared to wave fields produced with SAR winds that represent the two dominant wind regimes in the area: the bora (ENE direction) and sirocco (SE direction). Results show a good correlation between the waves forced with reanalysis wind and SAR wind. In addition, a validation of reanalysis is shown. This research demonstrates how Earth observation products, such as SAR wind fields, can be successfully up-taken into oceanographic modeling, producing similar downscaled wave fields when compared to waves forced with reanalysis wind.

  2. Research on characteristics of radiated noise of large cargo ship in shallow water

    NASA Astrophysics Data System (ADS)

    Liu, Yongdong; Zhang, Liang

    2017-01-01

    With the rapid development of the shipping industry, the number of the world's ship is gradually increasing. The characteristics of the radiated noise of the ship are also of concern. Since the noise source characteristics of multichannel interference, the surface wave and the sea temperature microstructure and other reasons, the sound signal received in the time-frequency domain has varying characteristics. The signal of the radiated noise of the large cargo ship JOCHOH from horizontal hydrophone array in some shallow water of China is processed and analyzed in the summer of 2015, and the results show that a large cargo ship JOCHOH has a number of noise sources in the direction of the ship's bow and stern lines, such as host, auxiliary and propellers. The radiating sound waves generated by these sources do not meet the spherical wave law at lower frequency in the ocean, and its radiated noise has inherent spatial distribution, the variation characteristics of the radiated noise the large cargo ship in time and frequency domain are given. The research method and results are of particular importance.

  3. Snorkelling and trampling in shallow-water fringing reefs: Risk assessment and proposed management strategy

    PubMed Central

    Hannak, Judith S.; Kompatscher, Sarah; Stachowitsch, Michael; Herler, Jürgen

    2011-01-01

    Shallow reefs (reef flats <1.5 m) in the northern Red Sea are impacted by growing tourism that includes swimmers, snorkellers and reef walkers but have largely been neglected in past studies. We selected a fringing reef along the lagoon of Dahab (Sinai, Egypt) as a model for a management strategy. Point-intercept line transects were used to determine substrate composition, coral community and condition, and the coral damage index (CDI) was applied. Approximately 84% of the coral colonies showed signs of damage such as breakage, partial mortality or algal overgrowth, especially affecting the most frequent coral genus Acropora. Questionnaires were used to determine the visitors’ socio-economic background and personal attitudes regarding snorkelling, SCUBA-diving and interest in visiting a prospective snorkelling trail. Experiencing nature (97%) was by far the strongest motivation, and interest in further education about reef ecology and skill training was high. Less experienced snorkellers and divers – the target group for further education and skill training – were those most prepared to financially support such a trail. We therefore recommend a guided underwater snorkelling trail and restricting recreational use to a less sensitive ‘ecotourism zone’ while protecting the shallow reef flat. Artificial structures can complete the trail and offer the opportunity to snorkel over deeper areas at unfavourable tide or wind conditions. This approach provides a strategy for the management and conservation of shallow-water reefs, which are facing increasing human impact here and elsewhere. PMID:21708420

  4. Global change and modern coral reefs: New opportunities to understand shallow-water carbonate depositional processes

    NASA Astrophysics Data System (ADS)

    Hallock, Pamela

    2005-04-01

    Human activities are impacting coral reefs physically, biologically, and chemically. Nutrification, sedimentation, chemical pollution, and overfishing are significant local threats that are occurring worldwide. Ozone depletion and global warming are triggering mass coral-bleaching events; corals under temperature stress lose the ability to synthesize protective sunscreens and become more sensitive to sunlight. Photo-oxidative stress also reduces fitness, rendering reef-building organisms more susceptible to emerging diseases. Increasing concentration of atmospheric CO 2 has already reduced CaCO 3 saturation in surface waters by more than 10%. Doubling of atmospheric CO 2 concentration over pre-industrial concentration in the 21st century may reduce carbonate production in tropical shallow marine environments by as much as 80%. As shallow-water reefs decline worldwide, opportunities abound for researchers to expand understanding of carbonate depositional systems. Coordinated studies of carbonate geochemistry with photozoan physiology and calcification, particularly in cool subtropical-transition zones between photozoan-reef and heterotrophic carbonate-ramp communities, will contribute to understanding of carbonate sedimentation under environmental change, both in the future and in the geologic record. Cyanobacteria are becoming increasingly prominent on declining reefs, as these microbes can tolerate strong solar radiation, higher temperatures, and abundant nutrients. The responses of reef-dwelling cyanobacteria to environmental parameters associated with global change are prime topics for further research, with both ecological and geological implications.

  5. Diagenetic overprint of original depositional architecture in a shallow water carbonate reservoir, Permian Basin, Texas

    SciTech Connect

    Ruppel, S.C.; Lucia, F.J.

    1996-12-31

    Permian shallow-water carbonate reservoirs are highly heterogeneous because of complex variations in depositional facies produced by high-frequency sea level rise and fall. Accordingly, establishment of a cycle stratigraphic framework is fundamental to defining reservoir heterogeneity. Because nearly all of these reservoirs have experienced multiple episodes of dolomitization and sulfate emplacement, however, permeability is a n of diagenetic overprint. The extent to which diagenesis can affect permeability development is dramatically displayed in the Grayburg Formation (middle Permian) at South Cowden field, Weit Texas. Three scales of cyclicity contribute to original depositional facies heterogeneity in the Grayburg; high-frequency cycles, averaging 3 meters in thickness, constitute the fundamental architectural element in the main reservoir interval. Despite original depositional heterogeneity due to this cyclicity, however, permeability development is substantially the result of two diagenetic events: (1) dolomite diagenesis in vertically burrowed wackestones and packstones and (2) late alteration and removal of anhydrite. Dolomite diagenesis in vertically burrowed wackestones and packstones has produced irregular vertical zones of higher permeability in mud-dominated bases of high-frequency cycles in leeward ramp-crest highstand successions. Because dolomite diagenesis is concentrated in burrowed highstand successions, the distribution of resultant permeability trends is partly constrained by patterns of longterm accommodation and high frequency cyclicity. Anhydrite diagenesis, which is characterized by conversion to gypsum or by complete removal of sulfate, is developed along basinward margins of the field and cross cuts original depositional framework.

  6. Diagenetic overprint of original depositional architecture in a shallow water carbonate reservoir, Permian Basin, Texas

    SciTech Connect

    Ruppel, S.C.; Lucia, F.J. )

    1996-01-01

    Permian shallow-water carbonate reservoirs are highly heterogeneous because of complex variations in depositional facies produced by high-frequency sea level rise and fall. Accordingly, establishment of a cycle stratigraphic framework is fundamental to defining reservoir heterogeneity. Because nearly all of these reservoirs have experienced multiple episodes of dolomitization and sulfate emplacement, however, permeability is a n of diagenetic overprint. The extent to which diagenesis can affect permeability development is dramatically displayed in the Grayburg Formation (middle Permian) at South Cowden field, Weit Texas. Three scales of cyclicity contribute to original depositional facies heterogeneity in the Grayburg; high-frequency cycles, averaging 3 meters in thickness, constitute the fundamental architectural element in the main reservoir interval. Despite original depositional heterogeneity due to this cyclicity, however, permeability development is substantially the result of two diagenetic events: (1) dolomite diagenesis in vertically burrowed wackestones and packstones and (2) late alteration and removal of anhydrite. Dolomite diagenesis in vertically burrowed wackestones and packstones has produced irregular vertical zones of higher permeability in mud-dominated bases of high-frequency cycles in leeward ramp-crest highstand successions. Because dolomite diagenesis is concentrated in burrowed highstand successions, the distribution of resultant permeability trends is partly constrained by patterns of longterm accommodation and high frequency cyclicity. Anhydrite diagenesis, which is characterized by conversion to gypsum or by complete removal of sulfate, is developed along basinward margins of the field and cross cuts original depositional framework.

  7. Integrating Sensors into a Marine Drone for Bathymetric 3D Surveys in Shallow Waters

    PubMed Central

    Giordano, Francesco; Mattei, Gaia; Parente, Claudio; Peluso, Francesco; Santamaria, Raffaele

    2015-01-01

    This paper demonstrates that accurate data concerning bathymetry as well as environmental conditions in shallow waters can be acquired using sensors that are integrated into the same marine vehicle. An open prototype of an unmanned surface vessel (USV) named MicroVeGA is described. The focus is on the main instruments installed on-board: a differential Global Position System (GPS) system and single beam echo sounder; inertial platform for attitude control; ultrasound obstacle-detection system with temperature control system; emerged and submerged video acquisition system. The results of two cases study are presented, both concerning areas (Sorrento Marina Grande and Marechiaro Harbour, both in the Gulf of Naples) characterized by a coastal physiography that impedes the execution of a bathymetric survey with traditional boats. In addition, those areas are critical because of the presence of submerged archaeological remains that produce rapid changes in depth values. The experiments confirm that the integration of the sensors improves the instruments’ performance and survey accuracy. PMID:26729117

  8. Tomographic inversion of geoacoustic properties in a range-dependent shallow-water environment.

    PubMed

    Pignot, P; Chapman, N R

    2001-09-01

    This paper presents a matched-field tomographic method to estimate the geoacoustic properties of the ocean bottom for a range-dependent medium in shallow water. The inversion method has been developed in order to interpret experimental data from the Haro Strait PRIMER sea trial. This experiment was carried out in June '96 and used low-frequency broadband signals that were received on three vertical line arrays. Inversion of the data is particularly difficult because of the complex bathymetry of the Haro Strait experimental site. For this inversion, a range-dependent ray code was developed to solve the forward problem, allowing an arbitrarily layered bottom environment. The inversion scheme is based on modeling the propagation time and the amplitude of the recorded data, and a simple new cost function is proposed. The signal ray paths are identified automatically using a simple process that compares calculated and measured travel times. Data from multiple source positions are used to invert the range dependence of the geoacoustic model. The environment is separated into segments, and within each segment the inversion is carried out layer by layer for a multilayer geoacoustic model. Starting with the topmost layer, the range-dependent thickness and sound speed are estimated via a Monte Carlo method. Inversion results are presented for synthetic and experimental data from the Haro Strait sea trial.

  9. Analysis of triangular C-grid finite volume scheme for shallow water flows

    NASA Astrophysics Data System (ADS)

    Shirkhani, Hamidreza; Mohammadian, Abdolmajid; Seidou, Ousmane; Qiblawey, Hazim

    2015-08-01

    In this paper, a dispersion relation analysis is employed to investigate the finite volume triangular C-grid formulation for two-dimensional shallow-water equations. In addition, two proposed combinations of time-stepping methods with the C-grid spatial discretization are investigated. In the first part of this study, the C-grid spatial discretization scheme is assessed, and in the second part, fully discrete schemes are analyzed. Analysis of the semi-discretized scheme (i.e. only spatial discretization) shows that there is no damping associated with the spatial C-grid scheme, and its phase speed behavior is also acceptable for long and intermediate waves. The analytical dispersion analysis after considering the effect of time discretization shows that the Leap-Frog time stepping technique can improve the phase speed behavior of the numerical method; however it could not damp the shorter decelerated waves. The Adams-Bashforth technique leads to slower propagation of short and intermediate waves and it damps those waves with a slower propagating speed. The numerical solutions of various test problems also conform and are in good agreement with the analytical dispersion analysis. They also indicate that the Adams-Bashforth scheme exhibits faster convergence and more accurate results, respectively, when the spatial and temporal step size decreases. However, the Leap-Frog scheme is more stable with higher CFL numbers.

  10. Dynamics of turbulent western-boundary currents at low latitude in a shallow-water model

    NASA Astrophysics Data System (ADS)

    Akuetevi, C. Q. C.; Wirth, A.

    2015-06-01

    The dynamics of low latitude turbulent western-boundary currents (WBCs) crossing the Equator are considered using numerical results from integrations of a reduced-gravity shallow-water model. For viscosity values of 1000 m2 s-1 and greater, the boundary layer dynamics compares well to the analytical Munk-layer solution. When the viscosity is reduced, the boundary layer becomes turbulent and coherent structures in the form of anticyclonic eddies, bursts (violent detachments of the viscous sub-layer, VSL) and dipoles appear. Three distinct boundary layers emerge, the VSL, the advective boundary layer and the extended boundary layer. The first is characterized by a dominant vorticity balance between the viscous transport and the advective transport of vorticity; the second by a balance between the advection of planetary vorticity and the advective transport of relative vorticity. The extended boundary layer is the area to which turbulent motion from the boundary extends. The scaling of the three boundary layer thicknesses with viscosity is evaluated. Characteristic scales of the dynamics and dissipation are determined. A pragmatic approach to determine the eddy viscosity diagnostically for coarse-resolution numerical models is proposed.

  11. Chemistry of calcium carbonate-rich shallow water sediments in the Bahamas

    SciTech Connect

    Morse, J.W.; Zullig, J.J.; Bernstein, L.D.; Millero, F.J.; Milne, P.; Mucci, A.; Choppin, G.R.

    1985-02-01

    The geochemistry of calcium carbonate-rich sediments from a variety of environments throughout the Bahamas was investigated with particular emphasis on the factors that control the pore water chemistry. Most sediments are supersaturated with respect to aragonite, the most abundant carbonate component. Experimental studies indicate that the observed in situ calcium carbonate ion activity products can often be produced as reversible metastable equilibria between the sediments and seawater. This is interpreted as being the result of interactions between the solutions and the minor high Mg-calcite component present in these sediments. Although the overlying waters are more supersaturated than the pore waters, carbonate dissolution, not precipitation, dominates in these sediments as a result of organic matter oxidation and the resulting increase in P/sub CO/sub 2//. The carbonate sediments of the Bahamas are remarkable for their purity, with the exception of special environments such as mangrove swamps and tidal flats with algal mats. Organic matter and heavy metal content is extremely low. Only minor sulfate reduction is occurring in most sediments. Phosphate is undetectable in all pore waters, probably as a result of adsorption on carbonate mineral surfaces. Other dissolved pore water components such as ammonia and DOC are much lower than typically found in shallow water fine-grained terrigeneous sediments.

  12. Bistatic scattering from flush and partially buried targets in shallow water

    NASA Astrophysics Data System (ADS)

    Veljkovic, Irena; Schmidt, Henrik; Tesei, Alessandra

    2003-10-01

    GOATS'98 experiment had as one of its objectives to explore the possibility of vastly increasing the coverage rate of shallow water mine countermeasures (MCM), especially for buried targets using subcritical seabed penetration. The evanescent incident field combined with 3D bistatic configuration brought about a rich and intricate set of physical phenomena occurring in the target scattering and radiation process. Resonance of manmade elastic targets is a pivotal concept distinguishing targets from rocks or other clutter. Nevertheless, burial in sediment results in a variety of modifications to the scattered response caused by different physical mechanisms, geometric constraints, and intrinsic sediment properties. It is the goal of this work to identify, analyze, and explain the fundamental effects of the outer sediment and the proximity of the seabed interface on the scattering from elastic shells insonified at subcritical incident angles in a bistatic configuration. Using time-frequency and spectral analysis, a new, more comprehensive, understanding of GOATS'98 experimental data was obtained distinguishing the effects of the acoustics environment from the resonant signature of buried elastic targets. To achieve this, and to further investigate the details of the scattering process a new target scattering module of OASES-3D modeling framework was used. [Work supported by ONR.

  13. Advances in Shallow-Water, High-Resolution Seafloor Mapping: Integrating an Autonomous Surface Vessel (ASV) Into Nearshore Geophysical Studies

    NASA Astrophysics Data System (ADS)

    Denny, J. F.; O'Brien, T. F.; Bergeron, E.; Twichell, D.; Worley, C. R.; Danforth, W. W.; Andrews, B. A.; Irwin, B.

    2006-12-01

    The U.S. Geological Survey (USGS) has been heavily involved in geological mapping of the seafloor since the 1970s. Early mapping efforts such as GLORIA provided broad-scale imagery of deep waters (depths > 400 meters) within the Exclusive Economic Zone (EEZ). In the early 1990's, the USGS research emphasis shifted from deep- to shallow-water environments (inner continental shelf, nearshore, estuaries) to address pertinent coastal issues such as erosion, sediment availability, sediment transport, vulnerability of coastal areas to natural and anthropogenic hazards, and resource management. Geologic framework mapping in these shallow- water environments has provided valuable data used to 1) define modern sediment distribution and thickness, 2) determine underlying stratigraphic and structural controls on shoreline behavior, and 3) enable onshore-to- offshore geologic mapping within the coastal zone when coupled with subaerial techniques such as GPR and topographic LIDAR. Research in nearshore areas presents technological challenges due to the dynamics of the environment, high volume of data collected, and the geophysical limitations of operating in very shallow water. In 2004, the USGS, in collaboration with NOAA's Coastal Services Center, began a multi-year seafloor mapping effort to better define oyster habitats within Apalachicola Bay, Florida, a shallow water estuary along the northern Gulf of Mexico. The bay poses a technological challenge due to its shallow depths (< 4-m) and high turbidity that prohibits the use of bathymetric LIDAR. To address this extreme shallow water setting, the USGS incorporated an Autonomous Surface Vessel (ASV) into seafloor mapping operations, in June 2006. The ASV is configured with a chirp sub-bottom profiler (4 24 kHz), dual-frequency chirp sidescan-sonar (100/500 kHz), single-beam echosounder (235 kHz), and forward-looking digital camera, and will be used to delineate the distribution and thickness of surficial sediment, presence

  14. From Alaska to Antarctica: Species boundaries and genetic diversity of Prasiola (Trebouxiophyceae), a foliose chlorophyte associated with the bipolar lichen-forming fungus Mastodia tessellata.

    PubMed

    Garrido-Benavent, Isaac; Pérez-Ortega, Sergio; de Los Ríos, Asunción

    2017-02-01

    Symbiotic associations between green algae (Chlorophyta) and fungi give rise to morphologically and eco-physiologically distinct entities, or so-called, lichens. In one of the most peculiar of these associations, the partners are species of the macroscopic genus Prasiola (Trebouxiophyceae) and the ascomycete Mastodia tessellata (Verrucariaceae). This is the only known case of a lichen symbiosis involving a foliose green alga. Despite intense research targeted at understanding the biology of this particular association, little is known about the genetic variability of its symbionts. This study focuses on the photobiont partner of this lichen and was designed to explore and compare its genetic diversity along a latitudinal axis from Alaska to Antarctica. Molecular sequence data were generated for three loci: two nuclear markers (nrITS, RPL10A) and one plastid-encoded marker (tufA). The usefulness of the Prasiola nrITS and RPL10A data was examined at the species and intraspecific levels. We used the population assignment tests implemented in BAPS and STRUCTURE and two algorithmic species delimitation procedures (ABGD, GMYC) to generate species boundary discovery hypotheses, which were subsequently tested using Bayes factors. Population genetic differentiation and structure were also assessed through fixation indices, polymorphism statistics and haplotype networks. Based on the results of the species validation method, we propose that at least two species of Prasiola associate with the lichen-forming fungus Mastodia tessellata. Of these, P. borealis is broadly distributed in Alaska, Tierra del Fuego and the Antarctic Peninsula, whereas the second, undescribed, species is restricted to the Antarctic Peninsula. We detected significant phylogeographic substructure in P. borealis, including greater haplotype diversity in the Tierra del Fuego populations. Our findings provide new data that will be useful to unravel the cryptic diversity and phylogeographic patterns of the

  15. Comparison of broadcast and wet-blade applications of 2,4-D and triclopyr for control of woody species and off target impacts on Conservation Reserve Program lands in Alaska

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mowing every 2 to 3 yrs is not controlling woody plant species on Interior Alaska Conservation Reserve Program lands, therefore alternative methods for managing these plant species need to be developed. A new application technology, the wet-blade mower, which pumps herbicide out to the mower blades ...

  16. Aragonite precipitation induced by anaerobic oxidation of methane in shallow-water seeps, Tyrrhenian Sea, Italy

    NASA Astrophysics Data System (ADS)

    Wiedling, Johanna; Kuhfuß, Hanna; Lott, Christian; Böttcher, Michael E.; Lichtschlag, Anna; Wegener, Gunter; Deusner, Christian; Bach, Wolfgang; Weber, Miriam

    2014-05-01

    In the shallow-water organic-poor silicate sands off the West coast of Elba, Italy, we found aragonite precipitates within a radius of 10 cm to methane seeps in 20 - 40 cm sediment depth. The shallow seep site was mapped by SCUBA diving and in an area of 100 m2 nine gas emission spots were observed. The gas emission, containing 73 Vol. % methane, was measured to be 0.72 L m-2 d-1. Findings of anaerobic methane oxidizing archea (ANME 1, 2, 2a, 2b) and sulphate reducing bacteria (SRB) as well as in vitro rate measurements of anaerobic oxidation of methane (AOM) with a maximum of 67 ± 7 nmol CH4 cm-3 d-1 led to the hypothesis that carbonate precipitation is coupled to these microbial processes. Porewater analysis showed elevated concentrations of dissolved inorganic carbon (DIC) (up to 15.5 mmol L-1) and hydrogen sulfide (up to 6.6 mmol L-1). The presence of bicarbonate and the ambient temperature (14 - 25 ° C) facilitate the precipitation of needle-shaped aragonite. Oxygen isotope compositions of the mineral are consistent with the ambient temperatures and may indicate a recent diagenetic formation of this mineral. Although precipitation should not be preserved in these sandy permeable sediments, influenced by seasonality, wave action, and fluid flow, we found up to 10-50 cm3 irregular pieces of cemented sand grains, very often encrusting dead seagrass rhizomes. Commonly known carbonate structures, especially from the deep sea, are chimneys, mounds, hardgrounds and nodules. These structures are well known from seep and vent sites, usually showing the same range of stable carbon isotope fractionation as the escaping methane. The permeable sediment at the Elba site possibly allows the gas to frequently change its pathway to the sediment surface and thus precipitation can occure at several spots and more irregular than in the reported sites. Preservation of precipitates, however, requires sufficient authigenic aragonite to be formed before fluid dynamics changed the

  17. Numerical experiments with an implicit particle filter for the shallow water equations

    NASA Astrophysics Data System (ADS)

    Souopgui, I.; Chorin, A. J.; Hussaini, M.

    2012-12-01

    The estimation of initial conditions for the shallow water equations for a given set of later data is a well known test problem for data assimilation codes. A popular approach to this problem is the variational method (4D-Var), i.e. the computation of the mode of the posterior probability density function (pdf) via the adjoint technique. Here, we improve on 4D-Var by computing the conditional mean (the minimum least square error estimator) rather than the mode (a biased estimator) and we do so with implicit sampling, a Monte Carlo (MC) importance sampling method. The idea in implicit sampling is to first search for the high-probability region of the posterior pdf and then to find samples in this region. Because the samples are concentrated in the high-probability region, fewer samples are required than with competing MC schemes. The search for the high-probability region can be implemented by a minimization that is very similar to the minimization in 4D-Var, and we make use of a 4D-Var code in our implementation. The samples are obtained by solving algebraic equations with a random right-hand-side. These equations can be solved efficiently, so that the additional cost of our approach, compared to traditional 4D-Var, is small. The long-term goal is to assimilate experimental data, obtained with the CORIOLIS turntable in Grenoble (France), to study the drift of a vortex. We present results from numerical twin experiments as a first step towards our long-term goal. We discretize the shallow water equations on a square domain (2.5m× 2.5m) using finite differences on a staggered grid of size 28× 28 and a fourth order Runge-Kutta. We assume open boundary conditions and estimate the initial state (velocities and surface height) given noisy observations of the state. We solve the optimization problem using a 4D-Var code that relies on a L-BFGS method; the random algebraic equations are solved with random maps, i.e. we look for solutions in given, but random, directions

  18. Shallow water radio-magnetotelluric (RMT) measurements in urban environment: A case study from Stockholm city

    NASA Astrophysics Data System (ADS)

    Mehta, Suman; Bastani, Mehrdad; Malehmir, Alireza; Wang, Shunguo; Pedersen, Laust

    2014-05-01

    The Radio-MagnetoTelluric (RMT) method uses the electromagnetic signal from distant radio transmitters in the frequency range 15 to 250 kHz. RMT applications in near-surface studies have already been well established. Two components of electric field and three components of magnetic field are measured. These measured components are related to each other via transfer functions which contain detailed information about the variation of electrical resistivity of the subsurface. The present study is carried out in the frame of TRUST (TRansparent Underground STructure) project supported by several research and public organizations as well as industry. The study area is located close to central Stockholm in Sweden where the Swedish traffic authority has planned to construct a 21-km long motorway to bypass the city. In order to reduce the impact on natural and cultural environments, 18 km of the motorway will be located in tunnels. The main objective of this study is thus to identify potential fracture zones and faults as well as the general geological settings. The proposed path of the tunnel partly passes under the Lake Mälaren at a depth of about 60 m. Thus a challenge was posed on the applicability of RMT method in shallow water environments. Successful applications of RMT measurements using the Uppsala University's EnviroMT system on land encouraged us to modify the system to acquire data over lake water especially in urban areas. Pioneered by the Geological Survey of Sweden (SGU), RMT data were collected over the Lake Mälaren in spring 2012. The prototype acquisition system did not only turn out to be appropriate for such a challenging environment, but it was also much more efficient as compared with land surveys. Fifty two lines including 1160 stations with an average spacing of 15 m were covered in three days. Cultural noise associated with the city-related environment had to be identified and filtered out before inversion could be carried out. Reliable estimates

  19. Proximate composition and fatty acid signatures of selected forage fish species in Prince William Sound, Alaska. Exxon Valdez Oil Spill Restoration Project 95121. Final report

    SciTech Connect

    Worth, G.A.J.; Miculka, T.A.

    1997-12-31

    The proximate composition and fatty acid signatures of several prey species, which are important for sea birds and marine mammals in Prince William Sound, Alaska, were determined. Fish were collected as part of the SEA cruises in the fall of 1995 and were frozen immediately and then shipped to Galveston for analysis. Fatty acid signatures of herring, pollock, and tomcod were consistent with previously reported data, Three different species of sole (English, rock, and flathead) were also consistent with previously reported data for yellowfin sole. Detailed analyses of individual rock fish suggest that this species may exhibit trends in some specific fatty acids (20:5 n-3, 22:6 n-3) which differ from herring or pollock.

  20. ANALYTICAL MODELS OF EXOPLANETARY ATMOSPHERES. I. ATMOSPHERIC DYNAMICS VIA THE SHALLOW WATER SYSTEM

    SciTech Connect

    Heng, Kevin; Workman, Jared E-mail: jworkman@coloradomesa.edu

    2014-08-01

    Within the context of exoplanetary atmospheres, we present a comprehensive linear analysis of forced, damped, magnetized shallow water systems, exploring the effects of dimensionality, geometry (Cartesian, pseudo-spherical, and spherical), rotation, magnetic tension, and hydrodynamic and magnetic sources of friction. Across a broad range of conditions, we find that the key governing equation for atmospheres and quantum harmonic oscillators are identical, even when forcing (stellar irradiation), sources of friction (molecular viscosity, Rayleigh drag, and magnetic drag), and magnetic tension are included. The global atmospheric structure is largely controlled by a single key parameter that involves the Rossby and Prandtl numbers. This near-universality breaks down when either molecular viscosity or magnetic drag acts non-uniformly across latitude or a poloidal magnetic field is present, suggesting that these effects will introduce qualitative changes to the familiar chevron-shaped feature witnessed in simulations of atmospheric circulation. We also find that hydrodynamic and magnetic sources of friction have dissimilar phase signatures and affect the flow in fundamentally different ways, implying that using Rayleigh drag to mimic magnetic drag is inaccurate. We exhaustively lay down the theoretical formalism (dispersion relations, governing equations, and time-dependent wave solutions) for a broad suite of models. In all situations, we derive the steady state of an atmosphere, which is relevant to interpreting infrared phase and eclipse maps of exoplanetary atmospheres. We elucidate a pinching effect that confines the atmospheric structure to be near the equator. Our suite of analytical models may be used to develop decisively physical intuition and as a reference point for three-dimensional magnetohydrodynamic simulations of atmospheric circulation.

  1. Suspended-solids flux at a shallow-water site in south San Francisco Bay, California

    USGS Publications Warehouse

    Lacy, Jessica R.; Schoellhamer, David H.; Burau, Jon R.

    1996-01-01

    Time series measurements of current velocity and suspended solids-concentration (SSC) made during December 1993 and March 1994 at a shallow-water site in South San Francisco Bay were used to estimate and compare suspended-solids flux during the two periods. In December, the average residual flux at the site was 2.88 g/m/s, to the northeast, whereas in March the average residual flux was four times greater, 12.2 g/m/s, and was directed to the southeast, the direction of flood tide. Residual flux was decomposed and the three components that accounted for most of the flux were analyzed: residual advective flux (Stokes drift flux (u'h'c), and dispersive flux, which is the tidal cycle correlation between velocity and SSC (u'h'c). During both periods, the Stokes drift flux was to the north, and the dispersive flux was to the southeast. In December, these two components, with nearly opposite directions, had the greatest magnitudes, resulting in a lower total residual flux. In March, the residual advective flux was greater than the Stokes drift flux and was in the same direction as the dispersive flux because of a southeasterly residual current. Wind data indicate that the residual current in March was induced by persistent northwest winds. The southeasterly dispersive flux in March and December was due to generally higher SSC on flood than ebb tides. Increases in SSC frequently occurred at low water (before flood tides). Comparison of calculated bottom orbital velocities to SSC identified wind waves as a mechanism of resuspension.

  2. Methods for Quantifying Shallow-Water Habitat Availability in the Missouri River

    SciTech Connect

    Hanrahan, Timothy P.; Larson, Kyle B.

    2012-04-09

    As part of regulatory requirements for shallow-water habitat (SWH) restoration, the U.S. Army Corps of Engineers (USACE) completes periodic estimates of the quantity of SWH available throughout the lower 752 mi of the Missouri River. To date, these estimates have been made by various methods that consider only the water depth criterion for SWH. The USACE has completed estimates of SWH availability based on both depth and velocity criteria at four river bends (hereafter called reference bends), encompassing approximately 8 river miles within the lower 752 mi of the Missouri River. These estimates were made from the results of hydraulic modeling of water depth and velocity throughout each bend. Hydraulic modeling of additional river bends is not expected to be completed for deriving estimates of available SWH. Instead, future estimates of SWH will be based on the water depth criterion. The objective of this project, conducted by the Pacific Northwest National Laboratory for the USACE Omaha District, was to develop geographic information system methods for estimating the quantity of available SWH based on water depth only. Knowing that only a limited amount of water depth and channel geometry data would be available for all the remaining bends within the lower 752 mi of the Missouri River, the intent was to determine what information, if any, from the four reference bends could be used to develop methods for estimating SWH at the remaining bends. Specifically, we examined the relationship between cross-section channel morphology and relative differences between SWH estimates based on combined depth and velocity criteria and the depth-only criterion to determine if a correction factor could be applied to estimates of SWH based on the depth-only criterion. In developing these methods, we also explored the applicability of two commonly used geographic information system interpolation methods (TIN and ANUDEM) for estimating SWH using four different elevation data

  3. Impacts of ocean acidification on sediment processes in shallow waters of the Arctic Ocean.

    PubMed

    Gazeau, Frédéric; van Rijswijk, Pieter; Pozzato, Lara; Middelburg, Jack J

    2014-01-01

    Despite the important roles of shallow-water sediments in global biogeochemical cycling, the effects of ocean acidification on sedimentary processes have received relatively little attention. As high-latitude cold waters can absorb more CO2 and usually have a lower buffering capacity than warmer waters, acidification rates in these areas are faster than those in sub-tropical regions. The present study investigates the effects of ocean acidification on sediment composition, processes and sediment-water fluxes in an Arctic coastal system. Undisturbed sediment cores, exempt of large dwelling organisms, were collected, incubated for a period of 14 days, and subject to a gradient of pCO2 covering the range of values projected for the end of the century. On five occasions during the experimental period, the sediment cores were isolated for flux measurements (oxygen, alkalinity, dissolved inorganic carbon, ammonium, nitrate, nitrite, phosphate and silicate). At the end of the experimental period, denitrification rates were measured and sediment samples were taken at several depth intervals for solid-phase analyses. Most of the parameters and processes (i.e. mineralization, denitrification) investigated showed no relationship with the overlying seawater pH, suggesting that ocean acidification will have limited impacts on the microbial activity and associated sediment-water fluxes on Arctic shelves, in the absence of active bio-irrigating organisms. Only following a pH decrease of 1 pH unit, not foreseen in the coming 300 years, significant enhancements of calcium carbonate dissolution and anammox rates were observed. Longer-term experiments on different sediment types are still required to confirm the limited impact of ocean acidification on shallow Arctic sediment processes as observed in this study.

  4. A nodal triangle-based spectral element method for the shallow water equations on the sphere

    NASA Astrophysics Data System (ADS)

    Giraldo, F. X.; Warburton, T.

    2005-07-01

    A nodal triangle-based spectral element (SE) method for the shallow water equations on the sphere is presented. The original SE method uses quadrilateral elements and high-order nodal Lagrange polynomials, constructed from a tensor-product of the Legendre-Gauss-Lobatto points. In this work, we construct the high-order Lagrange polynomials directly on the triangle using nodal sets obtained from the electrostatics principle [J.S. Hesthaven, From electrostatics to almost optimal nodal sets for polynomial interpolation in a simplex, SIAM Journal on Numerical Analysis 35 (1998) 655-676] and Fekete points [M.A. Taylor, B.A. Wingate, R.E. Vincent, An algorithm for computing Fekete points in the triangle, SIAM Journal on Numerical Analysis 38 (2000) 1707-1720]. These points have good approximation properties and far better Lebesgue constants than any other nodal set derived for the triangle. By employing triangular elements as the basic building-blocks of the SE method and the Cartesian coordinate form of the equations, we can use any grid imaginable including adaptive unstructured grids. Results for six test cases are presented to confirm the accuracy and stability of the method. The results show that the triangle-based SE method yields the expected exponential convergence and that it can be more accurate than the quadrilateral-based SE method even while using 30-60% fewer grid points especially when adaptive grids are used to align the grid with the flow direction. However, at the moment, the quadrilateral-based SE method is twice as fast as the triangle-based SE method because the latter does not yield a diagonal mass matrix.

  5. Long range dynamics of shallow water: renormalization, modulation and long cycles.

    NASA Astrophysics Data System (ADS)

    Gurarie, David

    2000-11-01

    Long-range dynamics of rotating shallow water (RSW) in the low Rossby-Froude regime, Ro = Fr ll1, exhibits multiscale structure with oscillations on different scales, from fast (gravity), to slower ``eddy turnover" , and yet slower ``long weather cycles". We search for an effective theory, that would ``average" fast oscillations on each scale, to produce higher level ``slow evolution". The principal source of fast gravity waves - dominant linear dispersion, could be eliminated by passing to the amplitude equations. In nonlinear systems, however, it does not remove oscillations completely, but transplants them to nonlinear terms. We implement the Bogoliubov-Mitropolskii averaging (BM) to produce renormalized system (RN-RSW), made of the resonant quadratic part of RSW, plus order(Ro) - cubic, and O(Ro^2) - quartic corrections. Renormalized system evolves on the first slow scale. Next we conduct the detailed analysis of RN-RSW for a single 9D-Lorenz-type triad. The triad system allows to implement second renormalization (from ``first slow" to ``second slow" time), based on its 5 adiabatic invariants: two conserved integrals of QGS-oscillator (a 3D subsystem, solvable in Jacobi elliptic functions), and three wave-intensities. The adiabatic invariants evolve on the second slow scale, and describe slow modulation of the basic QGS (Jacobi) parameters: modulus, period, magnitude. The off-shot of our two-step renormalization (BM followed by ``adiabatic averaging") are ``modulated oscillations" of the vortical and gravity modes. We verify the modulation phenomena by numeric simulations of (i) complete RSW-triad, vs. (ii) renormalized system (RN-RSW), vs. (iii) its ``modulated (adiabatic) approximation". All three show good qualitative agreement in their gross features. The analysis of adiabatic system explains some long range phases of the RSW-dynamics, like nonlinear ``relaxation", and ``intensification" regimes, and pinpoints ``modulation" as the principal long

  6. Hybrid ensemble 4DVar assimilation of stratospheric ozone using a global shallow water model

    NASA Astrophysics Data System (ADS)

    Allen, Douglas R.; Hoppel, Karl W.; Kuhl, David D.

    2016-07-01

    Wind extraction from stratospheric ozone (O3) assimilation is examined using a hybrid ensemble 4-D variational assimilation (4DVar) shallow water model (SWM) system coupled to the tracer advection equation. Stratospheric radiance observations are simulated using global observations of the SWM fluid height (Z), while O3 observations represent sampling by a typical polar-orbiting satellite. Four ensemble sizes were examined (25, 50, 100, and 1518 members), with the largest ensemble equal to the number of dynamical state variables. The optimal length scale for ensemble localization was found by tuning an ensemble Kalman filter (EnKF). This scale was then used for localizing the ensemble covariances that were blended with conventional covariances in the hybrid 4DVar experiments. Both optimal length scale and optimal blending coefficient increase with ensemble size, with optimal blending coefficients varying from 0.2-0.5 for small ensembles to 0.5-1.0 for large ensembles. The hybrid system outperforms conventional 4DVar for all ensemble sizes, while for large ensembles the hybrid produces similar results to the offline EnKF. Assimilating O3 in addition to Z benefits the winds in the hybrid system, with the fractional improvement in global vector wind increasing from ˜ 35 % with 25 and 50 members to ˜ 50 % with 1518 members. For the smallest ensembles (25 and 50 members), the hybrid 4DVar assimilation improves the zonal wind analysis over conventional 4DVar in the Northern Hemisphere (winter-like) region and also at the Equator, where Z observations alone have difficulty constraining winds due to lack of geostrophy. For larger ensembles (100 and 1518 members), the hybrid system results in both zonal and meridional wind error reductions, relative to 4DVar, across the globe.

  7. Application of 2D-Nonlinear Shallow Water Model of Tsunami by using Adomian Decomposition Method

    SciTech Connect

    Waewcharoen, Sribudh; Boonyapibanwong, Supachai; Koonprasert, Sanoe

    2008-09-01

    One of the most important questions in tsunami modeling is the estimation of tsunami run-up heights at different points along a coastline. Methods for numerical simulation of tsunami wave propagation in deep and shallow seas are well developed and have been widely used by many scientists (2001-2008). In this paper, we consider a two-dimensional nonlinear shallow water model of tsunami given by Tivon Jacobson is work [1]. u{sub t}+uu{sub x}+{nu}u{sub y} -c{sup 2}(h{sub x}+(h{sub b}){sub x}) {nu}{sub t}+u{nu}{sub x}+{nu}{nu}{sub y} = -c{sup 2}(h{sub y}+(h{sub b}){sub y}) h{sub t}+(hu){sub x}+(h{nu}){sub y} = 0 g-shore, h is surface elevation and s, t is time, u is velocity of cross-shore, {nu} is velocity of along-shore, h is surface elevation and h{sub b} is function of shore. This is a nondimensionalized model with the gravity g and constant reference depth H factored into c = {radical}(gH). We apply the Adomian Decompostion Method (ADM) to solve the tsunami model. This powerful method has been used to obtain explicit and numerical solutions of three types of diffusion-convection-reaction (DECR) equations. The ADM results for the tsunami model yield analytical solutions in terms of a rapidly convergent infinite power series. Symbolic computation, numerical results and graphs of solutions are obtained by Maple program.

  8. A piecewise modeling approach for climate sensitivity studies: Tests with a shallow-water model

    NASA Astrophysics Data System (ADS)

    Shao, Aimei; Qiu, Chongjian; Niu, Guo-Yue

    2015-10-01

    In model-based climate sensitivity studies, model errors may grow during continuous long-term integrations in both the "reference" and "perturbed" states and hence the climate sensitivity (defined as the difference between the two states). To reduce the errors, we propose a piecewise modeling approach that splits the continuous long-term simulation into subintervals of sequential short-term simulations, and updates the modeled states through re-initialization at the end of each subinterval. In the re-initialization processes, this approach updates the reference state with analysis data and updates the perturbed states with the sum of analysis data and the difference between the perturbed and the reference states, thereby improving the credibility of the modeled climate sensitivity. We conducted a series of experiments with a shallow-water model to evaluate the advantages of the piecewise approach over the conventional continuous modeling approach. We then investigated the impacts of analysis data error and subinterval length used in the piecewise approach on the simulations of the reference and perturbed states as well as the resulting climate sensitivity. The experiments show that the piecewise approach reduces the errors produced by the conventional continuous modeling approach, more effectively when the analysis data error becomes smaller and the subinterval length is shorter. In addition, we employed a nudging assimilation technique to solve possible spin-up problems caused by re-initializations by using analysis data that contain inconsistent errors between mass and velocity. The nudging technique can effectively diminish the spin-up problem, resulting in a higher modeling skill.

  9. Field evaluation of shallow-water acoustic doppler current profiler discharge measurements

    USGS Publications Warehouse

    Rehmel, M.S.

    2007-01-01

    In 2004, the U.S. Geological Survey (USGS) Office of Surface Water staff and USGS Water Science employees began testing the StreamPro, an acoustic Doppler current profiler (ADCP) for shallow-water discharge measurements. Teledyne RD Instruments introduced the StreamPro in December of 2003. The StreamPro is designed to make a "moving boat" discharge measurement in streams with depths between 0.15 and 2 m. If the StreamPro works reliably in these conditions, it will allow for use of ADCPs in a greater number of streams than previously possible. Evaluation sites were chosen to test the StreamPro over a range of conditions. Simultaneous discharge measurements with mechanical and other acoustic meters, along with stable rating curves at established USGS streamflow-gaging stations, were used for comparisons. The StreamPro measurements ranged in mean velocity from 0.076 to 1.04 m/s and in discharge from 0.083 m 3/s to 43.4 m 3/s. Tests indicate that discharges measured with the StreamPro compare favorably to the discharges measured with the other meters when the mean channel velocity is greater than 0.25 m/s. When the mean channel velocity is less than 0.25 m/s, the StreamPro discharge measurements for individual transects have greater variability than those StreamPro measurements where the mean channel velocity is greater than 0.25 m/s. Despite this greater variation in individual transects, there is no indication that the StreamPro measured discharges (the mean discharge for all transects) are biased, provided that enough transects are used to determine the mean discharge. ?? 2007 ASCE.

  10. A new approach to macroalgal bloom control in eutrophic, shallow-water, coastal areas.

    PubMed

    Lenzi, Mauro; Salvaterra, Giulia; Gennaro, Paola; Mercatali, Isabel; Persia, Emma; Porrello, Salvatore; Sorce, Carlo

    2015-03-01

    In summer 2012, an experiment was conducted in a shallow eutrophic lagoon with poor water exchange to determine the consequences of harvesting algae on the algal mat itself, which was traversed and repeatedly disturbed by large harvester boats. Four areas with high macroalgal density, measuring half a hectare each, were selected. Two were subjected to frequent disturbance of the algal mat and sediment (12 two-hour operations over a 38-day period) and the other two were left undisturbed as control. The following variables were determined: 1) water column physical chemistry and nutrients; 2) redox potential, nutrients and organic load in sediments; 3) C, N and P content of algal thalli; 4) macroalgal biomass. In 2013, a further experiment was conducted on a larger scale. Biomass was estimated in a high-density mat measuring 235 ha, where macroalgae were harvested and stirred up by four harvesting boats, and in two high-density mats measuring 150 and 120 ha, left undisturbed as control (9.15, 9.92 and 3.68 kg/m(2), respectively). In the first experiment, no significant changes were observed in the water column. In sediment the main variation was a significant reduction in labile organic matter in the disturbed areas and a significant increase mainly in refractory organic matter in the undisturbed areas. Biomass showed a significant drastic reduction in disturbed areas and substantial stability in undisturbed areas. In the large-scale experiment, the biomass of the disturbed mat declined by about 63%, only 6.5% of which was due to harvesting. On the other hand, the undisturbed mat with higher density underwent a natural decline in biomass of about 23% and the other increased by about 50%. These results demonstrate that disturbance of high-density mat in shallow water by boats can cause decay of the mat.

  11. Bottom attenuation estimation using sound intensity fluctuations due to mode coupling by nonlinear internal waves in shallow water.

    PubMed

    Grigorev, Valery A; Katsnelson, Boris G; Lynch, James F

    2016-11-01

    Analyses of fluctuations of low frequency signals (300 ± 30 Hz) propagating in shallow water in the presence of nonlinear internal waves (NIWs) in the Shallow Water 2006 experiment are carried out. Signals were received by a vertical line array at a distance of ∼20 km from the source. A NIW train was moving totally inside of the acoustic track, and the angle between the wave front of the NIW and the acoustic track in the horizontal plane was ∼10°. It is shown that the spectrum of the sound intensity fluctuations contains peaks corresponding to the coupling of pairs of propagating modes. Analysis of spectra at different hydrophone depths, and also summed over depth allows the authors to estimate attenuation in the bottom sediments.

  12. COMPARISON OF RECORDING CURRENT METERS USED FOR MEASURING VELOCITIES IN SHALLOW WATERS OF SAN FRANCISCO BAY, CALIFORNIA.

    USGS Publications Warehouse

    Gartner, Jeffrey W.; Oltmann, Richard N.

    1985-01-01

    The authors determine the feasibility of collecting reliable current-meter data in shallow water under natural conditions. The study involved field testing four types of recording current meters (different speed sensors) and comparing data recorded by the meters under different field conditions. Speeds recorded by the current meters at slack water and during maximum flows were compared during calm and windy conditions at various tide levels.

  13. An energy and potential enstrophy conserving numerical scheme for the multi-layer shallow water equations with complete Coriolis force

    NASA Astrophysics Data System (ADS)

    Stewart, Andrew L.; Dellar, Paul J.

    2016-05-01

    We present an energy- and potential enstrophy-conserving scheme for the non-traditional shallow water equations that include the complete Coriolis force and topography. These integral conservation properties follow from material conservation of potential vorticity in the continuous shallow water equations. The latter property cannot be preserved by a discretisation on a fixed Eulerian grid, but exact conservation of a discrete energy and a discrete potential enstrophy seems to be an effective substitute that prevents any distortion of the forward and inverse cascades in quasi-two dimensional turbulence through spurious sources and sinks of energy and potential enstrophy, and also increases the robustness of the scheme against nonlinear instabilities. We exploit the existing Arakawa-Lamb scheme for the traditional shallow water equations, reformulated by Salmon as a discretisation of the Hamiltonian and Poisson bracket for this system. The non-rotating, traditional, and our non-traditional shallow water equations all share the same continuous Hamiltonian structure and Poisson bracket, provided one distinguishes between the particle velocity and the canonical momentum per unit mass. We have determined a suitable discretisation of the non-traditional canonical momentum, which includes additional coupling between the layer thickness and velocity fields, and modified the discrete kinetic energy to suppress an internal symmetric computational instability that otherwise arises for multiple layers. The resulting scheme exhibits the expected second-order convergence under spatial grid refinement. We also show that the drifts in the discrete total energy and potential enstrophy due to temporal truncation error may be reduced to machine precision under suitable refinement of the timestep using the third-order Adams-Bashforth or fourth-order Runge-Kutta integration schemes.

  14. On the transition towards slow manifold in shallow-water and 3D Euler equations in a rotating frame

    NASA Technical Reports Server (NTRS)

    Mahalov, A.

    1994-01-01

    The long-time, asymptotic state of rotating homogeneous shallow-water equations is investigated. Our analysis is based on long-time averaged rotating shallow-water equations describing interactions of large-scale, horizontal, two-dimensional motions with surface inertial-gravity waves field for a shallow, uniformly rotating fluid layer. These equations are obtained in two steps: first by introducing a Poincare/Kelvin linear propagator directly into classical shallow-water equations, then by averaging. The averaged equations describe interaction of wave fields with large-scale motions on time scales long compared to the time scale 1/f(sub o) introduced by rotation (f(sub o)/2-angular velocity of background rotation). The present analysis is similar to the one presented by Waleffe (1991) for 3D Euler equations in a rotating frame. However, since three-wave interactions in rotating shallow-water equations are forbidden, the final equations describing the asymptotic state are simplified considerably. Special emphasis is given to a new conservation law found in the asymptotic state and decoupling of the dynamics of the divergence free part of the velocity field. The possible rising of a decoupled dynamics in the asymptotic state is also investigated for homogeneous turbulence subjected to a background rotation. In our analysis we use long-time expansion, where the velocity field is decomposed into the 'slow manifold' part (the manifold which is unaffected by the linear 'rapid' effects of rotation or the inertial waves) and a formal 3D disturbance. We derive the physical space version of the long-time averaged equations and consider an invariant, basis-free derivation. This formulation can be used to generalize Waleffe's (1991) helical decomposition to viscous inhomogeneous flows (e.g. problems in cylindrical geometry with no-slip boundary conditions on the cylinder surface and homogeneous in the vertical direction).

  15. Prawn landings and their relationship with the extent of mangroves and shallow waters in western peninsular Malaysia

    NASA Astrophysics Data System (ADS)

    Loneragan, N. R.; Ahmad Adnan, N.; Connolly, R. M.; Manson, F. J.

    2005-04-01

    This study investigated changes in landings of all prawns, white prawns (mainly Penaeus merguiensis), mangrove extent, rainfall and the area of shallow water in western peninsular Malaysia. The most important state for both the landings of all prawns and white prawns was Perak where about 50% of all prawns and 35% of white prawns were landed. This is also the state with the largest, and most stable, extent of mangrove forest reserve (40 000 ha) and the largest area of shallow water (<5 m deep). Juvenile prawns from Perak may contribute to the landings of the nearby, adjacent states of Penang and Selangor, where the second highest landings for white prawns and total prawns, respectively, were found. The area of shallow water accounted for the greatest proportion of variation in landings of both all prawns and white prawns, and was the most significant variable fitted to multiple regressions of landings and coastal attributes (area of shallow water, mangrove area, length of coastline). Although there was a significant linear relationship between the landings of total prawns and mangrove area in both the 1980s and 1990s, this was not the case for the mangrove-dependent white prawns where a significant relationship was found only for the 1990s. Furthermore, landings of all prawns and white prawns in Selangor and Johor, where large losses of mangrove forest reserve have been recorded, appear to have been maintained or increased in the 1990s. The lack of a clear relationship between mangrove loss and prawn landings may be due to the migration of prawns from adjacent areas or that other attributes of mangroves, such as the length of mangrove-water interface, may be more important for the growth and survival of prawn populations than total area of mangroves.

  16. An eigenvector-based linear reconstruction scheme for the shallow-water equations on two-dimensional unstructured meshes

    NASA Astrophysics Data System (ADS)

    Soares Frazão, Sandra; Guinot, Vincent

    2007-01-01

    This paper presents a new approach to MUSCL reconstruction for solving the shallow-water equations on two-dimensional unstructured meshes. The approach takes advantage of the particular structure of the shallow-water equations. Indeed, their hyperbolic nature allows the flow variables to be expressed as a linear combination of the eigenvectors of the system. The particularity of the shallow-water equations is that the coefficients of this combination only depend upon the water depth. Reconstructing only the water depth with second-order accuracy and using only a first-order reconstruction for the flow velocity proves to be as accurate as the classical MUSCL approach. The method also appears to be more robust in cases with very strong depth gradients such as the propagation of a wave on a dry bed. Since only one reconstruction is needed (against three reconstructions in the MUSCL approach) the EVR method is shown to be 1.4-5 times as fast as the classical MUSCL scheme, depending on the computational application.

  17. Stability analysis of unstructured finite volume methods for linear shallow water flows using pseudospectra and singular value decomposition

    NASA Astrophysics Data System (ADS)

    Beljadid, Abdelaziz; Mohammadian, Abdolmajid; Qiblawey, Hazim

    2016-10-01

    The discretization of the shallow water system on unstructured grids can lead to spurious modes which usually can affect accuracy and/or cause stability problems. This paper introduces a new approach for stability analysis of unstructured linear finite volume schemes for linear shallow water equations with the Coriolis Effect using spectra, pseudospectra, and singular value decomposition. The discrete operator of the scheme is the principal parameter used in the analysis. It is shown that unstructured grids have a large influence on operator normality. In some cases the eigenvectors of the operator can be far from orthogonal, which leads to amplification of solutions and/or stability problems. Large amplifications of the solution can be observed, even for discrete operators which respect the condition of asymptotic stability, and in some cases even for Lax-Richtmyer stable methods. The pseudospectra are shown to be efficient for the verification of stability of finite volume methods for linear shallow water equations. In some cases, the singular value decomposition is employed for further analysis in order to provide more information about the existence of unstable modes. The results of the analysis can be helpful in choosing the type of mesh, the appropriate placements of the variables of the system on the grid, and the suitable discretization method which is stable for a wide range of modes.

  18. A study of electric field components in shallow water and water half-space models in seabed logging

    NASA Astrophysics Data System (ADS)

    Rostami, Amir; Soleimani, Hassan; Yahya, Noorhana; Nyamasvisva, Tadiwa Elisha; Rauf, Muhammad

    2016-11-01

    Seabed logging (SBL) is an electromagnetic (EM) method to detect hydrocarbon (HC) laid beneath the seafloor, which is a development of marine controlled source electromagnetic (CSEM) method. CSEM is a method to show resistivity log of geological layers, transmitting ultra-low frequency EM wave. In SBL a net of receivers, placed on the seafloor, detect reflected and refracted EM wave by layers with different resistivity. Contrast of electrical resistivity of layers impacts on amplitude and phase of the EM wave response. The most indispensable concern in SBL is to detect guided wave via high resistive layer under the seafloor that can be an HC reservoir. Guided wave by HC creates a remarkable difference in received signal when HC reservoir does not exist. While the major contribution of received EM wave in large offset, especially in shallow water environment, is airwave, which is refracted by sea surface due to extremely high resistivity of atmosphere, airwave can affect received guided wave, dramatically. Our objective for this work is to compare HC delineation of tangential and normal components of electric field in shallow water area, using finite element method simulation. Will be reported that, in shallow water environment, minor contribution of air wave in normal component of E field (Ey) versus its major contribution in the tangential component (Ex), causes a considerable contrast on HC delineation of Ey for deeply buried reservoirs (more than 3000 m), while Ex is unable to show different contrasts of received data for with and without HC media at the same condition.

  19. Combined Effect of Reduced Band Number and Increased Bandwidth on Shallow Water Remote Sensing: The Case of WorldView 2

    DTIC Science & Technology

    2013-05-01

    on Shallow Water Remote Sensing : The Case of WorldView 2 N/A NNH09AM26I 73-4223-01-5 ZhongPing Lee, Alan Weidemann, and Robert Arnone Naval Research...Presentation The Combined Effect of Reduced Spectral Bands and Increased Bandwidth on Shallow Water Remote Sensing : The Case of WorldView 2...ON GEOSCIENCE AND REMOTE SENSING , VOL. 51, NO. 5, MAY 2013 2577 Combined Effect of Reduced Band Number and Increased Bandwidth on Shallow Water Remote

  20. A Dynamic Eddy Viscosity Model for the Shallow Water Equations Solved by Spectral Element and Discontinuous Galerkin Methods

    NASA Astrophysics Data System (ADS)

    Marras, Simone; Suckale, Jenny; Giraldo, Francis X.; Constantinescu, Emil

    2016-04-01

    We present the solution of the viscous shallow water equations where viscosity is built as a residual-based subgrid scale model originally designed for large eddy simulation of compressible [1] and stratified flows [2]. The necessity of viscosity for a shallow water model not only finds motivation from mathematical analysis [3], but is supported by physical reasoning as can be seen by an analysis of the energetics of the solution. We simulated the flow of an idealized wave as it hits a set of obstacles. The kinetic energy spectrum of this flow shows that, although the inviscid Galerkin solutions -by spectral elements and discontinuous Galerkin [4]- preserve numerical stability in spite of the spurious oscillations in the proximity of the wave fronts, the slope of the energy cascade deviates from the theoretically expected values. We show that only a sufficiently small amount of dynamically adaptive viscosity removes the unwanted high-frequency modes while preserving the overall sharpness of the solution. In addition, it yields a physically plausible energy decay. This work is motivated by a larger interest in the application of a shallow water model to the solution of tsunami triggered coastal flows. In particular, coastal flows in regions around the world where coastal parks made of mitigation hills of different sizes and configurations are considered as a means to deviate the power of the incoming wave. References [1] M. Nazarov and J. Hoffman (2013) "Residual-based artificial viscosity for simulation of turbulent compressible flow using adaptive finite element methods" Int. J. Numer. Methods Fluids, 71:339-357 [2] S. Marras, M. Nazarov, F. X. Giraldo (2015) "Stabilized high-order Galerkin methods based on a parameter-free dynamic SGS model for LES" J. Comput. Phys. 301:77-101 [3] J. F. Gerbeau and B. Perthame (2001) "Derivation of the viscous Saint-Venant system for laminar shallow water; numerical validation" Discrete Contin. Dyn. Syst. Ser. B, 1:89?102 [4] F

  1. Promoting invasive species control and eradication in the sea: options for managing the tunicate invader Didemnum vexillum in Sitka, Alaska.

    PubMed

    McCann, Linda D; Holzer, Kimberly K; Davidson, Ian C; Ashton, Gail V; Chapman, Marnie D; Ruiz, Gregory M

    2013-12-15

    Bioinvasions are a significant force of change--and economic and ecological threat--in marine ecosystems. The threat now encroaches on Alaska, which has had relatively few invasions compared to other global regions, prompting need to develop new incursion response tools. We appraised five 'eco-friendly' immersion treatment options (dilute acetic acid, dilute bleach, freshwater, brine and hypoxia) at either minute- or hour-scale exposures to kill the invasive tunicate Didemnum vexillum. Data revealed 100% treatment efficacy after two minutes in acetic acid, ten minutes in bleach, four hours in freshwater and over four hours in brine solution. We also demonstrated the importance of monitoring D. vexillum recovery for at least three weeks, since seemingly destroyed colonies rebounded during this timeframe. Combined, these findings provide insights towards a bay-scale eradication and post-border management plan applicable to the recent D. vexillum incursion in Whiting Harbor, Alaska and other shallow, inshore invasion sites.

  2. Initial-Boundary Value Problem Solution of the Nonlinear Shallow-water Wave Equations

    NASA Astrophysics Data System (ADS)

    Kanoglu, U.; Aydin, B.

    2014-12-01

    The hodograph transformation solutions of the one-dimensional nonlinear shallow-water wave (NSW) equations are usually obtained through integral transform techniques such as Fourier-Bessel transforms. However, the original formulation of Carrier and Greenspan (1958 J Fluid Mech) and its variant Carrier et al. (2003 J Fluid Mech) involve evaluation integrals. Since elliptic integrals are highly singular as discussed in Carrier et al. (2003), this solution methodology requires either approximation of the associated integrands by smooth functions or selection of regular initial/boundary data. It should be noted that Kanoglu (2004 J Fluid Mech) partly resolves this issue by simplifying the resulting integrals in closed form. Here, the hodograph transform approach is coupled with the classical eigenfunction expansion method rather than integral transform techniques and a new analytical model for nonlinear long wave propagation over a plane beach is derived. This approach is based on the solution methodology used in Aydın & Kanoglu (2007 CMES-Comp Model Eng) for wind set-down relaxation problem. In contrast to classical initial- or boundary-value problem solutions, here, the NSW equations are formulated to yield an initial-boundary value problem (IBVP) solution. In general, initial wave profile with nonzero initial velocity distribution is assumed and the flow variables are given in the form of Fourier-Bessel series. The results reveal that the developed method allows accurate estimation of the spatial and temporal variation of the flow quantities, i.e., free-surface height and depth-averaged velocity, with much less computational effort compared to the integral transform techniques such as Carrier et al. (2003), Kanoglu (2004), Tinti & Tonini (2005 J Fluid Mech), and Kanoglu & Synolakis (2006 Phys Rev Lett). Acknowledgments: This work is funded by project ASTARTE- Assessment, STrategy And Risk Reduction for Tsunamis in Europe. Grant 603839, 7th FP (ENV.2013.6.4-3 ENV

  3. Statistical equilibria of the coupled barotropic flow and shallow water flow on a rotating sphere

    NASA Astrophysics Data System (ADS)

    Ding, Xueru

    The motivation of this research is to build equilibrium statistical models that can apply to explain two enigmatic phenomena in the atmospheres of the solar system's planets: (1) the super-rotation of the atmospheres of slowly-rotating terrestrial planets---namely Venus and Titan, and (2) the persistent anticyclonic large vortex storms on the gas giants, such as the Great Red Spot (GRS) on Jupiter. My thesis is composed of two main parts: the first part focuses on the statistical equilibrium of the coupled barotropic vorticity flow (non-divergent) on a rotating sphere; the other one has to do with the divergent shallow water flow rotating sphere system. The statistical equilibria of these two systems are simulated in a wide range of parameter space by Monte Carlo methods based on recent energy-relative enstrophy theory and extended energy-relative enstrophy theory. These kind of models remove the low temperatures defect in the old classical doubly canonical energy-enstrophy theory which cannot support any phase transitions. The other big difference of our research from previous work is that we work on the coupled fluid-sphere system, which consists of a rotating high density rigid sphere, enveloped by a thin shell of fluid. The sphere is considered to have infinite mass and angular momentum; therefore, it can serve as a reservoir of angular momentum. Unlike the fluid sphere system itself, the coupled fluid sphere system allows for the exchange of angular momentum between the atmosphere and the solid planet. This exchange is the key point in any model that is expected to capture coherent structures such as the super-rotation and GRS-like vortices problems in planetary atmospheres. We discovered that slowly-rotating planets can have super-rotation at high energy state. All known slowly-rotating cases in the solar system---Venus and Titan---have super-rotation. Moreover, we showed that the anticyclonicity in the GRS-like structures is closely associated with the

  4. Shallow water submarine hydrothermal activity - A case study in the assessment of ocean acidification and fertilization

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Yoshida, K.; Hagiwara, T.; Nagao, K.; Kusakabe, M.; Wang, B.; Chen, C. A.

    2012-12-01

    Most natural Shallow Water submarine Hydrothermal activates (SWH) along coastlines are related to hydrothermal eruptions involving heating of groundwater with the volcanic gas. These SWHs supply nutrients such as phosphorus and micro nutrients like iron to the euphotic zone, contributing to the overall natural fertility and primary productivity of coastal waters. However, SWHs also have a negative effect, dispersing toxic materials such as mercury and arsenic, and affecting the acidification of the surrounding waters. In this study, we evaluate the impact of "iron supply" and "ocean acidification" on the primary production in a coastal marine environment, at a SWH area discovered off Gueshandao Island, northeast Taiwan. In the past three years, expeditions were conducted and observations made around this SWH site. Divers, small boats and a research vessel (R/V OR1, Ocean University National Taiwan) were used to survey successively larger areas around the site. Some of the results obtained are as follows. Hydrothermal vents are located in a hilly terrain rich with hot spring water with gas erupting intermittently. There are two types of vents, roughly divided by color, yellow hot spring water with higher temperature >110 degC ejected from sulfur chimneys of various sizes, and colorless water with lower temperature ~80 degC ejected directly from the crevices of the andesitic bedrock. Natural sulfur solidifying in the mouth of a small chimney was captured by a video camera, and explosions were also observed at intervals of a few minutes. Sediment, sand and particles of sulfur were deposited on the sides to a radius of about 50 m condensing around the chimney. The bottom type changes from sand/particles to outcrop/rock away from the vents. Moreover, gas samples were collected from the vents; the ratios of gas concentrations (N2/Ar) and isotopic composition of noble gas (3He/4He) suggest that these volcanic gases are mantle-derived. Hydrothermal fluid with high p

  5. Instabilities of Tropical Cyclones and their Nonlinear Saturation in Moist-Convective Rotating Shallow Water Model

    NASA Astrophysics Data System (ADS)

    Lahaye, N.; Zeitlin, V.

    2015-12-01

    Studies of stability of tropical cyclones (TC) are mostly performed either in over-simplified (2D Euler, e.g. [1]), or in over-complexified "all-inclusive", e.g. [2], models. TC have very high Rossby numbers, so Lighthill radiation is operational and instabilities are radiative. Yet, the quantitative results for radiative instabilities of vortices are available only for simplified vortex profiles, e.g. [3]. TC evolve in the essentially moist and precipitating atmosphere, yet studies of precise dynamical role of moisture in developing instability are scarce [4]. We use the moist-convective Rotating Shallow Water model of [5], the simplest possible one which includes inertia-gravity gravity waves (IGW) and the effects of moisture and precipitation. Unstable modes are investigated by means of a linear stability analysis, then the nonlinear saturation is simulated in cases with precipitation off (dry), precipitation on but evaporation off (moist-precipitating), and precipitation and evaporation on (moist-precipitating-evaporating). Our main results are: Linear stability: Main instability: ageostrophic barotropic instability Unstable modes: mixed Rossby - inertia gravity waves. Dry saturation: Axisymmetrization of the TC Intensification of winds inside the radius of maximum wind Bursts in the IGW emission Moist-precipitating saturation: Amplification of the IGW emission with respect to the dry case Amplification of the wind intensification mechanism Moist-precipitating-evaporating saturation: Appearance of convectively-coupled IGWs Net intensification of wind (even at the radius of maximum wind) References: J.P. Kossin and W.H. Schubert, J. Atmos. Sci., 58, 2196, 2001. Y.C. Kwon and W.M. Frank, J. Atmos. Sci., 65, 106, 2008. S. Le Dizes and P. Billant, Phys. Fluids, 21, 1, 2009. D.A. Schecter and M.T. Montgomery, J. Atmos. Sci., 64, 314, 2007. F. Bouchut, J. Lambaerts, G. Lapeyre, and V. Zeitlin, Phys. Fluids, 21, 126601, 2009. Figure: Nondimensional vorticity (colors

  6. Analysis of transmission loss, signal gain, and coherence in shallow water

    NASA Astrophysics Data System (ADS)

    Rozenfeld, Ilya

    2001-08-01

    Experiments in the Strait of Korea were performed to study sound propagation in an oceanographically complex shallow water environment. First a geoacoustic model is developed based on narrowband transmission loss measurements and using estimated profiles and measured bathymetry. The comparisons between measured and calculated transmission loss are made through an effective attenuation coefficient, which measures the rate of change of mean transmission loss with range. Environmental model parameters are selected to achieve the best agreement in the comparisons. Nonlinear frequency dependence in the sediment attenuation profiles permits good agreement between the calculations and measured data. The developed geoacoustic model is then used to obtain predictions of broadband transmission loss and signal energy spread. Very good agreement between these predictions and corresponding independent measurements validates the geoacoustic model. Next signal gain measurements taken during the experiment are examined. Using the previously developed environmental profiles the signal gain is computed. The calculations are in agreement with measurements for shorter ranges. For longer ranges and higher frequencies disagreement is found between the calculations and measurements. The cause is random fluctuations in the signal induced by the random medium. These effects can be included into the signal gain through the coherence function. Using a previously developed theory preliminary calculations of coherence are made. By choosing physically reasonable parameters of the random fluctuations in the medium, close agreement with measurements is achieved. Next this theory is extended to include scattering from inhomogeneities with arbitrary correlation functions. This allows a treatment of random fluctuations described by physically based spectra. The correlation functions corresponding to these spectra for mechanisms such as internal waves, turbulence, and wind driven sea surface

  7. Process-oriented tests for validation of baroclinic shallow water models: The lock-exchange problem

    NASA Astrophysics Data System (ADS)

    Kolar, R. L.; Kibbey, T. C. G.; Szpilka, C. M.; Dresback, K. M.; Tromble, E. M.; Toohey, I. P.; Hoggan, J. L.; Atkinson, J. H.

    A first step often taken to validate prognostic baroclinic codes is a series of process-oriented tests, as those suggested by Haidvogel and Beckmann [Haidvogel, D., Beckmann, A., 1999. Numerical Ocean Circulation Modeling. Imperial College Press, London], among others. One of these tests is the so-called "lock-exchange" test or "dam break" problem, wherein water of different densities is separated by a vertical barrier, which is removed at time zero. Validation against these tests has primarily consisted of comparing the propagation speed of the wave front, as predicted by various theoretical and experimental results, to model output. In addition, inter-model comparisons of the lock-exchange test have been used to validate codes. Herein, we present a high resolution data set, taken from a laboratory-scale model, for direct and quantitative comparison of experimental and numerical results throughout the domain, not just the wave front. Data is captured every 0.2 s using high resolution digital photography, with salt concentration extracted by comparing pixel intensity of the dyed fluid against calibration standards. Two scenarios are discussed in this paper, symmetric and asymmetric mixing, depending on the proportion of dense/light water (17.5 ppt/0.0 ppt) in the experiment; the Boussinesq approximation applies to both. Front speeds, cast in terms of the dimensionless Froude number, show excellent agreement with literature-reported values. Data are also used to quantify the degree of mixing, as measured by the front thickness, which also provides an error band on the front speed. Finally, experimental results are used to validate baroclinic enhancements to the barotropic shallow water ADvanced CIRCulation (ADCIRC) model, including the effect of the vertical mixing scheme on simulation results. Based on salinity data, the model provides an average root-mean-square (rms) error of 3.43 ppt for the symmetric case and 3.74 ppt for the asymmetric case, most of which can

  8. Linear acoustic sensitivity kernels and their applications in shallow water environments

    NASA Astrophysics Data System (ADS)

    Sarkar, Bikramjit

    Time of arrival information from acoustic transmissions is the primary means through which ocean sound-speed structure is estimated. While initially limited to large scale coarse observations using ray theory to model the propagation of sound through the environment, ocean acoustic tomography evolved to incorporate a normal-mode representation of observed peak-arrivals. This wave-theoretic approach was enhanced, using the first Born approximation to perturbations in the wave equation, producing the travel-time sensitivity kernel (TSK): a linear relationship between sound-speed variations and observed changes in arrival times. This dissertation extends sensitivity kernel analysis to both the amplitude and phase of complex-demodulated broadband acoustic transmissions, producing both a qualitative and quantitative picture of how ocean sound-speed variability affects acoustic observations, and complementing prior work on travel-time sensitivity. The linearity and information content of these kernels is explored in simulation for a 3--4 kHz broadband pulse transmission through a 1 km shallow-water Pekeris waveguide, and in simulated inversions with a more realistic summer-type sound-speed profile, the results from which demonstrate the additional information amplitude contains over phase data alone. Differences in phase measurements were assumed to be directly relatable to travel-time changes, and thus the phase sensitivity kernel was expected to represent the same details as the travel-time sensitivity kernel. However, even a cursory visual inspection of the two kernel types shows that they have different spatial structures and hence different sensitivities to changes in the environment. A numerical survey was conducted comparing the performance of these sensitivity kernels (along with amplitude) to observations from perturbed simulations---including a synthetic time-evolving ocean---and the results suggest that phase and peak travel-time do indeed diverge in the

  9. An investigation into mechanical strength of exoskeleton of hydrothermal vent shrimp (Rimicaris exoculata) and shallow water shrimp (Pandalus platyceros) at elevated temperatures.

    PubMed

    Verma, Devendra; Tomar, Vikas

    2015-04-01

    This investigation reports a comparison of the exoskeleton mechanical strength of deep sea shrimp species Rimicaris exoculata and shallow water shrimp species Pandalus platyceros at temperatures ranging from 25°C to 80°C using nanoindentation experiments. Scanning Electron Microscopy (SEM) observations suggest that both shrimp exoskeletons have the Bouligand structure. Differences in the structural arrangement and chemical composition of both shrimps are highlighted by SEM and EDX (Energy Dispersive X-ray) analyses. The variation in the elastic moduli with temperature is found to be correlated with the measured compositional differences. The reduced modulus of R. exoculata is 8.26±0.89GPa at 25°C that reduces to 7.61±0.65GPa at 80°C. The corresponding decrease in the reduced modulus of P. platyceros is from 27.38±2.3GPa at 25°C to 24.58±1.71GPa at 80°C. The decrease in reduced moduli as a function of temperature is found to be dependent on the extent of calcium based minerals in exoskeleton of both types of shrimp exoskeletons.

  10. Two new cestode species of Neoskrjabinolepis Spasskii, 1947 (Cyclophyllidea: Hymenolepididae) from the tundra shrew Sorex tundrensis Merriam (Mammalia: Soricidae) in Alaska and Chukotka.

    PubMed

    Kornienko, Svetlana A; Dokuchaev, Nikolaj E

    2012-11-01

    Descriptions, illustrations and differential diagnoses for two new species of Neoskrjabinolepis Spassky, 1947, i.e. N. (Neoskrjabinolepis) fertilis n. sp. and N. (Neoskrjabinolepidoides) hobergi n. sp., are given. Neoskrjabinolepis (Neoskrjabinolepis) fertilis was found in the shrew Sorex tundrensis Merriam on the Seward Peninsula (Alaska, USA) and from the mouth of the Anadyr River (Chukotka, Russia), and N. (Neoskrjabinolepidoides) hobergi was found in Sorex tundrensis on the Seward Peninsula (Alaska, USA). Neoskrjabinolepis fertilis n. sp. is characterised by having: rostellar hooks 38-42 μm long and provided with a small epiphyseal thickening of the handle; a long cirrus (85-100 μm), consisting of a basal region with claw-shaped spines and a parabasal region with small, thin needle-shaped spines; a cirrus-sac extending well into the median field; and 55-70 eggs per gravid uterus. Neoskrjabinolepis (Neoskrjabinolepidoides) hobergi n. sp. is characterised by having: rostellar hooks 63-65 μm long and provided with a large epiphyseal thickening of the handle; a short cirrus (45-50 μm), consisting of a basal region with small claw-shaped spines and a parabasal region with thin, needle-shaped spines; cirrus-sac reaching slightly into the median field; and 36-45 eggs per gravid uterus.

  11. Application of conservative residual distribution schemes to the solution of the shallow water equations on unstructured meshes

    NASA Astrophysics Data System (ADS)

    Ricchiuto, M.; Abgrall, R.; Deconinck, H.

    2007-03-01

    We consider the numerical solution of the shallow water equations on unstructured grids. We focus on flows over wet areas. The extension to the case of dry bed will be reported elsewhere. The shallow water equations fall into the category of systems of conservation laws which can be symmetrized thanks to the existence of a mathematical entropy coinciding, in this case, with the total energy. Our aim is to show the application of a particular class of conservative residual distribution (RD) schemes to the discretization of the shallow water equations and to analyze their discrete accuracy and stability properties. We give a review of conservative RD schemes showing relations between different approaches previously published, and recall L∞ stability and accuracy criteria characterizing the schemes. In particular, the accuracy of the RD method in presence of source terms is analyzed, and conditions to construct rth order discretizations on irregular triangular grids are proved. It is shown that the RD approach gives a natural way of obtaining high order discretizations which, moreover, preserves exactly the steady lake at rest solution independently on mesh topology, nature of the variation of the bottom and polynomial order of interpolation used for the unknowns. We also consider more general analytical solutions which are less investigated from the numerical view point. On irregular grids, linearity preserving RD schemes yield a truly second order approximation. We also sketch a strategy to achieve discretizations which preserve exactly some of these solutions. Numerical results on steady and time-dependent problems involving smooth and non-smooth variations of the bottom topology show very promising features of the approach.

  12. UNIT, ALASKA.

    ERIC Educational Resources Information Center

    Louisiana Arts and Science Center, Baton Rouge.

    THE UNIT DESCRIBED IN THIS BOOKLET DEALS WITH THE GEOGRAPHY OF ALASKA. THE UNIT IS PRESENTED IN OUTLINE FORM. THE FIRST SECTION DEALS PRINCIPALLY WITH THE PHYSICAL GEOGRAPHY OF ALASKA. DISCUSSED ARE (1) THE SIZE, (2) THE MAJOR LAND REGIONS, (3) THE MOUNTAINS, VOLCANOES, GLACIERS, AND RIVERS, (4) THE NATURAL RESOURCES, AND (5) THE CLIMATE. THE…

  13. Development of a Finite-Difference Time Domain (FDTD) Model for Propagation of Transient Sounds in Very Shallow Water.

    PubMed

    Sprague, Mark W; Luczkovich, Joseph J

    2016-01-01

    This finite-difference time domain (FDTD) model for sound propagation in very shallow water uses pressure and velocity grids with both 3-dimensional Cartesian and 2-dimensional cylindrical implementations. Parameters, including water and sediment properties, can vary in each dimension. Steady-state and transient signals from discrete and distributed sources, such as the surface of a vibrating pile, can be used. The cylindrical implementation uses less computation but requires axial symmetry. The Cartesian implementation allows asymmetry. FDTD calculations compare well with those of a split-step parabolic equation. Applications include modeling the propagation of individual fish sounds, fish aggregation sounds, and distributed sources.

  14. Solving the shallow water equations on the Cray X-MP/48 and the connection machine 2

    NASA Technical Reports Server (NTRS)

    Swarztrauber, Paul N.; Sato, Richard K.

    1989-01-01

    The shallow water equations in Cartesian coordinates and 2-D are solved on the Connection Machine 2 (CM-2) using both the spectral and finite difference methods. A description of these implementations is presented together with a brief discussion of the CM-2 as it relates to these specific computations. The finite difference code was written both in C* and *LISP and the spectral code was written in *LISP. The performance of the codes is compared with a FORTRAN version that was optimized for the Cray X-MP/48.

  15. A lattice Boltzmann-finite element model for two-dimensional fluid-structure interaction problems involving shallow waters

    NASA Astrophysics Data System (ADS)

    De Rosis, Alessandro

    2014-03-01

    In this paper, a numerical method for the modeling of shallow waters interacting with slender elastic structures is presented. The fluid domain is modeled through the lattice Boltzmann method, while the solid domain is idealized by corotational beam finite elements undergoing large displacements. Structure dynamics is predicted by using the time discontinuous Galerkin method and the fluid-structure interface conditions are handled by the Immersed Boundary method. An explicit coupling strategy to combine the adopted numerical methods is proposed and its effectiveness is tested by computing the error in terms of the energy that is artificially introduced at the fluid-solid interface.

  16. Study on shallow-water delta characteristics by utilizing seismic sedimentologic methods in Zilaitun Oilfield, Huanghua Depression, East China

    NASA Astrophysics Data System (ADS)

    Liu, Shan; Wang, Jiahao

    2015-04-01

    Shallow-water delta is characterized by widely distributed distributary channels from plentiful previous studies. But how to tenuously depict its planar geomorphology remains a difficult problem at present. This paper discussed the feasibility of seismic sedimentologic methods to interpret distributary channels distribution and summarized shallow-water delta characteristics. Huanghua Depression of Bohai Bay Basin is the Cenozoic rift basin in east China. Zilaitun Oilfield lies in the Kongdian buried-hill belt of Huanghua Depression. The oil layer is mainly distributed in the Paleocene Kongdian Formation. From core samples, 1st member of Kongdian Formation mainly consists of finer grain-size sandstone and amaranth mudstone, revealing a shallow-water environment. In the sandstone of distributary channels, sedimentary structures such as erosional surface, lag deposit, parallel bedding and trough cross-bedding are developed, illustrating an intensive hydrodynamic condition. Combining logging data, shallow-water delta mainly developed delta front subfacies. Microfacies of the delta front include subaqueous distributary channel, mouth bar and interdistributary bay in study area. A vertical discontinuous sequence was formed on account of the lack of distal bar. Subaqueous distributary channels are characterized by cylinder and conical well log curves. By extraction of RMS amplitudes from 3-D seismic data, seismic strata slices reveal banding distribution of sand bodies. Cylinder and conical logging curves demonstrated that these sand bodies are developed in distributary channels. The NE-trending anastomosing and dendritic distributary channels are widely developed in 1st member of Kongdian Formation. When the lake expanded, the river frequently bifurcated and diverted due to the rise of the relative lake-level, forming deep and wide anastomosing distributary channels. These channels extended as far as 13.2 km. The width is from 600 m to 1000 m. The average thickness of

  17. New glass sponges (Porifera: Hexactinellida) from deep waters of the central Aleutian Islands, Alaska.

    PubMed

    Reiswig, Henry M; Stone, Robert P

    2013-01-01

    Hexactinellida from deep-water communities of the central Aleutian Islands, Alaska, are described. They were mostly collected by the remotely operated vehicle 'Jason II' from 494–2311 m depths during a 2004 RV 'Roger Revelle' expedition, but one shallow-water species collected with a shrimp trawl from 155 m in the same area is included. The excellent condition of the ROV-collected specimens enabled valuable redescription of some species previously known only from badly damaged specimens. New taxa include one new genus and eight new species in five families. Farreidae consist of two new species, Farrea aleutiana and F. aspondyla. Euretidae consists of only Pinulasma fistulosum n. gen., n. sp. Tretodictyidae include only Tretodictyum amchitkensis n. sp. Euplectellidae consists of only the widespread species Regadrella okinoseana Ijima, reported here over 3,700 km from its closest previously known occurrence. The most diverse family, Rossellidae, consists of Aulosaccus ijimai (Schulze), Aulosaccus schulzei Ijima, Bathydorus sp. (young stage not determinable to species), Caulophacus (Caulophacus) adakensis n. sp., Acanthascus koltuni n. sp., Staurocalyptus psilosus n. sp., Staurocalyptus tylotus n. sp. and Rhabdocalyptus mirabilis Schulze. We present argument for reinstatement of the abolished rossellid subfamily Acanthascinae and return of the subgenera  Staurocalyptus Ijima and Rhabdocalyptus Schulze to their previous generic status. These fauna provides important complexity to the hard substrate communities that likely serve as nursery areas for the young stages of commercially important fish and crab species, refuge from predation for both young and adult stages, and also as a focal source of prey for juvenile and adult stages of those same species.

  18. Shallow-water Ascidians from Matua Island (central Kuril Islands, NW Pacific).

    PubMed

    Sanamyan, Karen; Sanamyan, Nadya

    2017-02-16

    Fifteen species of ascidians were identified in the material collected at Matua Island. Two species are new, Botryllus flavus n. sp. and Distaplia matua n. sp. The first species occurs also at Kamchatka waters, while the second is probably an endemic of Kuril Islands. The genus Macrenteron Redikorzev, 1927 is synonymized with Aplidium Savigny, 1816 and a new name Aplidium macrenteron nom. nov. is proposed for its type species.

  19. Evaluating signals of oil spill impacts, climate, and species interactions in Pacific herring and Pacific salmon populations in Prince William Sound and Copper River, Alaska.

    PubMed

    Ward, Eric J; Adkison, Milo; Couture, Jessica; Dressel, Sherri C; Litzow, Michael A; Moffitt, Steve; Hoem Neher, Tammy; Trochta, John; Brenner, Rich

    2017-01-01

    The Exxon Valdez oil spill occurred in March 1989 in Prince William Sound, Alaska, and was one of the worst environmental disasters on record in the United States. Despite long-term data collection over the nearly three decades since the spill, tremendous uncertainty remains as to how significantly the spill affected fishery resources. Pacific herring (Clupea pallasii) and some wild Pacific salmon populations (Oncorhynchus spp.) in Prince William Sound declined in the early 1990s, and have not returned to the population sizes observed in the 1980s. Discerning if, or how much of, this decline resulted from the oil spill has been difficult because a number of other physical and ecological drivers are confounded temporally with the spill; some of these drivers include environmental variability or changing climate regimes, increased production of hatchery salmon in the region, and increases in populations of potential predators. Using data pre- and post-spill, we applied time-series methods to evaluate support for whether and how herring and salmon productivity has been affected by each of five drivers: (1) density dependence, (2) the EVOS event, (3) changing environmental conditions, (4) interspecific competition on juvenile fish, and (5) predation and competition from adult fish or, in the case of herring, humpback whales. Our results showed support for intraspecific density-dependent effects in herring, sockeye, and Chinook salmon, with little overall support for an oil spill effect. Of the salmon species, the largest driver was the negative impact of adult pink salmon returns on sockeye salmon productivity. Herring productivity was most strongly affected by changing environmental conditions; specifically, freshwater discharge into the Gulf of Alaska was linked to a series of recruitment failures-before, during, and after EVOS. These results highlight the need to better understand long terms impacts of pink salmon on food webs, as well as the interactions between

  20. Evaluating signals of oil spill impacts, climate, and species interactions in Pacific herring and Pacific salmon populations in Prince William Sound and Copper River, Alaska

    PubMed Central

    Adkison, Milo; Couture, Jessica; Dressel, Sherri C.; Litzow, Michael A.; Moffitt, Steve; Hoem Neher, Tammy; Trochta, John

    2017-01-01

    The Exxon Valdez oil spill occurred in March 1989 in Prince William Sound, Alaska, and was one of the worst environmental disasters on record in the United States. Despite long-term data collection over the nearly three decades since the spill, tremendous uncertainty remains as to how significantly the spill affected fishery resources. Pacific herring (Clupea pallasii) and some wild Pacific salmon populations (Oncorhynchus spp.) in Prince William Sound declined in the early 1990s, and have not returned to the population sizes observed in the 1980s. Discerning if, or how much of, this decline resulted from the oil spill has been difficult because a number of other physical and ecological drivers are confounded temporally with the spill; some of these drivers include environmental variability or changing climate regimes, increased production of hatchery salmon in the region, and increases in populations of potential predators. Using data pre- and post-spill, we applied time-series methods to evaluate support for whether and how herring and salmon productivity has been affected by each of five drivers: (1) density dependence, (2) the EVOS event, (3) changing environmental conditions, (4) interspecific competition on juvenile fish, and (5) predation and competition from adult fish or, in the case of herring, humpback whales. Our results showed support for intraspecific density-dependent effects in herring, sockeye, and Chinook salmon, with little overall support for an oil spill effect. Of the salmon species, the largest driver was the negative impact of adult pink salmon returns on sockeye salmon productivity. Herring productivity was most strongly affected by changing environmental conditions; specifically, freshwater discharge into the Gulf of Alaska was linked to a series of recruitment failures—before, during, and after EVOS. These results highlight the need to better understand long terms impacts of pink salmon on food webs, as well as the interactions between

  1. The Multitentaculate Cirratulidae of the Genera Cirriformia and Timarete (Annelida: Polychaeta) from Shallow Waters of Brazil

    PubMed Central

    Magalhães, Wagner F.; Seixas, Victor Corrêa; Paiva, Paulo Cesar; Elias, Rodolfo

    2014-01-01

    A large number multitentaculate cirratulids have been described worldwide but most are only known through the original descriptions. Type material, voucher and recently collected specimens from Brazil were revisited in order to reveal their true identity and confirm the records of widely distributed species in this region. Six species are described, three of which are new, Cirriformia capixabensis sp. nov., Cirriformia chicoi sp. nov. and Timarete ceciliae sp. nov. COI and 16S sequences were obtained and used for inter-specific comparisons. Timarete caribous is reported from several localities along the Brazilian coast and a new synonym, Cirratulus melanacanthus, is proposed. The species Timarete oculata, originally described from Brazil and lumped into the Timarete filigera species complex, is herein revalidated and redescribed. The occurrence of the species Timarete filigera and Cirriformia tentaculata is not confirmed from the Brazilian coast. Descriptions, illustrations and a key to genera and species are provided. PMID:25393759

  2. Well-balanced high-order centered schemes on unstructured meshes for shallow water equations with fixed and mobile bed

    NASA Astrophysics Data System (ADS)

    Canestrelli, Alberto; Dumbser, Michael; Siviglia, Annunziato; Toro, Eleuterio F.

    2010-03-01

    In this paper, we study the numerical approximation of the two-dimensional morphodynamic model governed by the shallow water equations and bed-load transport following a coupled solution strategy. The resulting system of governing equations contains non-conservative products and it is solved simultaneously within each time step. The numerical solution is obtained using a new high-order accurate centered scheme of the finite volume type on unstructured meshes, which is an extension of the one-dimensional PRICE-C scheme recently proposed in Canestrelli et al. (2009) [5]. The resulting first-order accurate centered method is then extended to high order of accuracy in space via a high order WENO reconstruction technique and in time via a local continuous space-time Galerkin predictor method. The scheme is applied to the shallow water equations and the well-balanced properties of the method are investigated. Finally, we apply the new scheme to different test cases with both fixed and movable bed. An attractive future of the proposed method is that it is particularly suitable for engineering applications since it allows practitioners to adopt the most suitable sediment transport formula which better fits the field data.

  3. An efficient exponential time integration method for the numerical solution of the shallow water equations on the sphere

    NASA Astrophysics Data System (ADS)

    Gaudreault, Stéphane; Pudykiewicz, Janusz A.

    2016-10-01

    The exponential propagation methods were applied in the past for accurate integration of the shallow water equations on the sphere. Despite obvious advantages related to the exact solution of the linear part of the system, their use for the solution of practical problems in geophysics has been limited because efficiency of the traditional algorithm for evaluating the exponential of Jacobian matrix is inadequate. In order to circumvent this limitation, we modify the existing scheme by using the Incomplete Orthogonalization Method instead of the Arnoldi iteration. We also propose a simple strategy to determine the initial size of the Krylov space using information from previous time instants. This strategy is ideally suited for the integration of fluid equations where the structure of the system Jacobian does not change rapidly between the subsequent time steps. A series of standard numerical tests performed with the shallow water model on a geodesic icosahedral grid shows that the new scheme achieves efficiency comparable to the semi-implicit methods. This fact, combined with the accuracy and the mass conservation of the exponential propagation scheme, makes the presented method a good candidate for solving many practical problems, including numerical weather prediction.

  4. High-frequency underwater acoustic communications using FH-FSK signaling in a reverberant shallow water environment

    NASA Astrophysics Data System (ADS)

    Yang, Wen-Bin; Yang, T. C.

    2003-10-01

    This paper describes the experimental results of frequency-hopped frequency-shift-key (FH-FSK) signaling operated at 20 kHz with a 4 kHz bandwidth for underwater acoustic communications in a reverberant shallow water environment. The data were collected during the RDS4 (Rapidly Deployable Systems) experiment in a shallow water (<80 m depth) near Halifax, Canada. The measured impulse response function showed multipaths lasting over a second, which is an order of magnitude longer than the symbol length. Time-varying Doppler shifts of 30-70 Hz were found in the data. The long multipath delay and high Doppler shift are found to have a significant impact on data processing. For example, using conventional processing that detects the symbol energy over the symbol duration, the bit error rates (BER) are of the order 30-40%. Using a longer time window allowing integration of multipath energy and using Doppler estimated from trigger signals, the uncoded BER is reduced to 10-15%. The data are error-free after error decoding using a convolutional code with a rate and constraint length of 9. Consequences for acoustic networking will be discussed. [Work supported by ONR.

  5. High frequency normal mode statistics in a shallow water waveguide: the effect of random linear internal waves.

    PubMed

    Raghukumar, Kaustubha; Colosi, John A

    2014-07-01

    Using transport theory and Monte Carlo numerical simulation, the statistical properties of mode propagation at a frequency of 1 kHz are studied in a shallow water environment with random sound-speed perturbations from linear internal waves. The environment is typical of summer conditions in the mid-Atlantic bight during the Shallow Water 2006 experiment. Observables of interest include the second and fourth moments of the mode amplitudes, which are relevant to full-field mean intensity and scintillation index. It is found that mode phase randomization has a strong adiabatic component while at the same time mode coupling rates are significant. As a consequence, a computationally efficient transport theory is presented, which models cross-mode correlation adiabatically, but accounts for mode coupling using the mode energy equations of Creamer [(1996). J. Acoust. Soc. Am. 99, 2825-2838]. The theory also has closed-form expressions for the internal wave scattering matrix and a correction for an edge effect. The hybrid transport theory is shown to accurately reproduce many statistical quantities from the Monte Carlo simulations.

  6. Fenxiang biota: a new Early Ordovician shallow-water fauna with soft-part preservation from China.

    PubMed

    Balinski, Andrzej; Sun, Yuanlin

    Our perception of biodiversity in the geological past is incomplete and biased because most organisms did not have mineralized skeletons and therefore had little chance of fossilization. This especially refers to shallow-water marine environments, rarely represented by localities with exceptional preservation of fossil material (known as taphonomic windows or Konservat-Lagerstätten). Such extraordinary "windows" may markedly broaden our knowledge of biodiversity of the past. Here, we show a review of the invertebrate fossils from recently discovered locality in the Lower Ordovician Fenxiang Formation of Hubei Province in southern China revealing exceptional preservation of soft tissues. The fauna, generally of shallow-water aspect, contains linguloid brachiopods with a remarkably preserved pedicle, the oldest traces of nematode life activities, the oldest reliable record of hydroids, the first fossil antipatharian corals, a pyritized colonial organism of unknown affinity, supposed arthropod appendages, probable phosphatized scalidophoran worm embryo and other fossils. Our discovery supports the opinion that the famous soft-bodied preservation of Burgess Shale- or Chengjiang-type did not vanish from the fossil record in post-Cambrian times. The new finding represents a prelude to the Great Ordovician Biodiversification Event and provides evidence for calibration of molecular clock of several invertebrate lineages.

  7. Application of Airborne Hydrographic Laser Scanning for Mapping Shallow Water Riverine Environments in the Pacific Northwest, United States

    NASA Astrophysics Data System (ADS)

    Cooper, C.; Nayegandhi, A.; Faux, R.

    2013-12-01

    Small-footprint, green wavelength airborne LiDAR systems can provide seamless topography across the land-water interface at very high spatial resolution. These data have the potential to improve floodplain modeling, fisheries habitat assessments, stream restoration efforts, and other applications by continuously mapping shallow water depths that are difficult or impossible to measure using traditional ground-based or water-borne survey techniques. WSI (Corvallis, Oregon) in collaboration with Dewberry, (Tampa, Florida) and Riegl (Orlando, Florida), deployed the Riegl VQ-820-G hydrographic airborne laser scanner to map riverine and lacustrine environments from Oregon to Minnesota. Discussion will focus on the ability to accurately map depth and underwater structure, as well as riparian vegetation and terrain under different conditions. Results indicate that depth penetration varies with both water (i.e. clarity and surface conditions) and bottom conditions (i.e. substrate, depth, and landform). Depth penetration was typically limited to 1 Secchi depth or less across selected project areas. As an example, the green LiDAR system effectively mapped 83% of a shallow water river system, the Sandy River, with typical depths ranging from 0-2.5 meters. WSI will show quantitative comparisons of Green LiDAR surveys against more traditional methods such as rod or sonar surveys. WSI will also discuss advantages and limitations of Green LiDAR surveys for bathymetric modeling including survey accuracy, density, and efficiency along with data processing challenges not inherent with traditional NIR LiDAR processing.

  8. Observations of shallow water marine ambient sound: the low frequency underwater soundscape of the central Oregon coast.

    PubMed

    Haxel, Joseph H; Dziak, Robert P; Matsumoto, Haru

    2013-05-01

    A year-long experiment (March 2010 to April 2011) measuring ambient sound at a shallow water site (50 m) on the central OR coast near the Port of Newport provides important baseline information for comparisons with future measurements associated with resource development along the inner continental shelf of the Pacific Northwest. Ambient levels in frequencies affected by surf-generated noise (f < 100 Hz) characterize the site as a high-energy end member within the spectrum of shallow water coastal areas influenced by breaking waves. Dominant sound sources include locally generated ship noise (66% of total hours contain local ship noise), breaking surf, wind induced wave breaking and baleen whale vocalizations. Additionally, an increase in spectral levels for frequencies ranging from 35 to 100 Hz is attributed to noise radiated from distant commercial ship commerce. One-second root mean square (rms) sound pressure level (SPLrms) estimates calculated across the 10-840 Hz frequency band for the entire year long deployment show minimum, mean, and maximum values of 84 dB, 101 dB, and 152 dB re 1 μPa.

  9. Evaluation of the heat flux on the bottom boundary in shallow waters

    NASA Astrophysics Data System (ADS)

    Debolskaya, Elena; Ivanov, Alexandre

    2014-05-01

    is so small compared to the turbulent one) at different wind velocities W , will in any case not too low values of depths where the influence of the upper boundary condition is essential. It is easy to calculate that the effect of diurnal variations of temperature at the upper boundary depends on the wind velocity as follows: at W=0.5m/s K0=10-5m2/s, H=1.6 m; at W=1 m/s K0=2.6•10-4 m2/s, H=5m; at W=5 m/s K0=3•10-3 m2/s, H=16m. Further we can estimate the ability of the soil to respond to water temperature changes and to effect on the heat content of the overlying column of fluid, i.e., to serve as a source of stored heat. We consider a set of factors, that support such accumulation, namely, the shallow water with strong winds and calculate the relation of the temperature on the surface of the reservoir with depth H = 0.5 m and on the bottom during the daily fluctuation of temperature and upon the action of the wind with velocity of W = 5m / s. We obtain T(H,t)=0.95 T0, i.e. almost the whole water column warmed uniformly. Let us consider now the soil layer, on the surface of which there is a periodic variation of temperature of the overlying water with amplitude T(H,t)=0.95 T0. This problem is also described by the one-dimensional heat conduction equation with periodic boundary conditions at the upper boundary. The coefficient of thermal diffusivity of the soil at least one order of magnitude less than that of water. Let us find the value of soil depth (distance from the boundary "bottom -water"), where decrease in the amplitude of heat exposure is 10 times at daily fluctuations. We use the expression obtained above for water column and at the value of thermal diffusivity 10-7 m2/s and daily temperature variations with 86400 s, we obtain H = 0.12m. Below this depth the temperature remains relatively constant and heat flux is absent. Thus, the daily fluctuations of temperature, even for very small and well-mixed reservoir, can not propagate in depth of sediments to

  10. A Novel Colonial Ciliate Zoothamnium ignavum sp. nov. (Ciliophora, Oligohymenophorea) and Its Ectosymbiont Candidatus Navis piranensis gen. nov., sp. nov. from Shallow-Water Wood Falls

    PubMed Central

    Schuster, Lukas; Bright, Monika

    2016-01-01

    Symbioses between ciliate hosts and prokaryote or unicellular eukaryote symbionts are widespread. Here, we report on a novel ciliate species within the genus Zoothamnium Bory de St. Vincent, 1824, isolated from shallow-water sunken wood in the North Adriatic Sea (Mediterranean Sea), proposed as Zoothamnium ignavum sp. nov. We found this ciliate species to be associated with a novel genus of bacteria, here proposed as “Candidatus Navis piranensis” gen. nov., sp. nov. The descriptions of host and symbiont species are based on morphological and ultrastructural studies, the SSU rRNA sequences, and in situ hybridization with symbiont-specific probes. The host is characterized by alternate microzooids on alternate branches arising from a long, common stalk with an adhesive disc. Three different types of zooids are present: microzooids with a bulgy oral side, roundish to ellipsoid macrozooids, and terminal zooids ellipsoid when dividing or bulgy when undividing. The oral ciliature of the microzooids runs 1¼ turns in a clockwise direction around the peristomial disc when viewed from inside the cell and runs into the infundibulum, where it makes another ¾ turn. The ciliature consists of a paroral membrane (haplokinety), three adoral membranelles (polykineties), and one stomatogenic kinety (germinal kinety). One circular row of barren kinetosomes is present aborally (trochal band). Phylogenetic analyses placed Z. ignavum sp. nov. within the clade II of the polyphyletic family Zoothamniidae (Oligohymenophorea). The ectosymbiont was found to occur in two different morphotypes, as rods with pointed ends and coccoid rods. It forms a monophyletic group with two uncultured Gammaproteobacteria within an unclassified group of Gammaproteobacteria, and is only distantly related to the ectosymbiont of the closely related peritrich Z. niveum (Hemprich and Ehrenberg, 1831) Ehrenberg, 1838. PMID:27683199

  11. An Integrated Approach to Understand Relationships Between Shallow Water Benthic Community Structure and Ecosystem Function

    DTIC Science & Technology

    2008-11-01

    Benthic Index of Biotic Integrity BPI Biomass of pollution indicative species BPS Biomass of pollution sensitive species C:N carbon to nitrogen ratio...the most developed regions of the United States . In addition to recreational and leisure activities, these areas support commercial fishing...the most developed regions of the United States . In addition to recreational and leisure activities, these areas support commercial fishing

  12. Elevated concentrations of arsenic, predominance of thioarsenates, and orpiment precipitation on the seafloor at the marine shallow-water hydrothermal system off Milos Island, Greece

    NASA Astrophysics Data System (ADS)

    Price, R. E.; Planer-Friedrich, B.; Savov, I. P.; Pichler, T.

    2009-12-01

    Marine shallow-water hydrothermal vents off Milos Island, Greece, are discharging a low pH, high temperature, highly sulfidic brine into the coastal ocean. We present here the discovery that hydrothermal fluids are extremely elevated in arsenic (maximum ~78 μM (5.9 mg/L)), or almost 3000 times sea water concentration). This is the highest concentration of arsenic reported for marine hydrothermal vents to date. Ion microprobe analysis confirmed that red hydrothermal precipitates on the seafloor are orpiment (As2S3). Two sites were investigated; Palaeochori Bay, where abundant gas discharge is surrounded by large white and red patches of hydrothermal precipitates in 3-5 meters water depth, and Spathi Bay, a deeper site (~18 meters) where large patches of white hydrothermal precipitates occur. Total arsenic was measured on the hydrothermal fluids, as well as on fluids from brown areas surrounding the white and red patches. These 4 areas contained total arsenic concentrations of 20 (brown), 640 (white), 2700 (red), and 5900 μg/L (Spathi). Arsenic speciation analysis of the hydrothermal fluids revealed arsenite, arsenate, and mono-, di-, and trithioarsenate as the major species present in hydrothermal fluids. Fluids from the red area at Palaeochori Bay contained predominantly arsenite (77 %) followed by arsenate (14 %), then monothioarsenate (7 %) and dithioarsenate (1%). The hydrothermal fluids from the Palaeochori Bay white area were dominantly arsenite (49 %) and dithioarsenate (29 %), followed by arsenate, monothioarsenate, and trithioarsenate (9, 9, and 2 %, respectively). The brown area in Palaeochori Bay contained a similar distribution of arsenic species compared to the white area, only at much lower concentrations. Finally, the Spathi Bay site, which contained overall higher H2S and lower pH, was dominated by trithioarsenate (50%), followed by arsenite (24%), dithioarsenate (22%), and low abundances of monothioarsenate (3%) and arsenate (1%). Each of the

  13. Deferrisoma paleochoriense sp. nov., a thermophilic, iron(III)-reducing bacterium from a shallow-water hydrothermal vent in the Mediterranean Sea

    USGS Publications Warehouse

    Perez-Rodriguez, Ileana M.; Rawls, Matthew; Coykendall, Dolly K.; Foustoukos, Dionysis I.

    2016-01-01

    A novel thermophilic, anaerobic, mixotrophic bacterium, designated strain MAG-PB1T, was isolated from a shallow-water hydrothermal vent system in Palaeochori Bay off the coast of the island of Milos, Greece. The cells were Gram-negative, rugose, short rods, approximately 1.0 μm long and 0.5 μm wide. Strain MAG-PB1T grew at 30–70 °C (optimum 60 °C), 0–50 g NaCl l− 1 (optimum 15–20 g l− 1) and pH 5.5–8.0 (optimum pH 6.0). Generation time under optimal conditions was 2.5 h. Optimal growth occurred under chemolithoautotrophic conditions with H2 as the energy source and CO2 as the carbon source. Fe(III), Mn(IV), arsenate and selenate were used as electron acceptors. Peptone, tryptone, Casamino acids, sucrose, yeast extract, d-fructose, α-d-glucose and ( − )-d-arabinose also served as electron donors. No growth occurred in the presence of lactate or formate. The G+C content of the genomic DNA was 66.7 mol%. Phylogenetic analysis of the 16S rRNA gene sequence indicated that this organism is closely related to Deferrisoma camini, the first species of a recently described genus in the Deltaproteobacteria. Based on the 16S rRNA gene phylogenetic analysis and on physiological, biochemical and structural characteristics, the strain was found to represent a novel species, for which the name Deferrisoma palaeochoriense sp. nov. is proposed. The type strain is MAG-PB1T ( = JCM 30394T = DSM 29363T). 

  14. Discontinuous Galerkin methods for dispersive shallow water models in closed basins: Spurious eddies and their removal using curved boundary methods

    NASA Astrophysics Data System (ADS)

    Steinmoeller, D. T.; Stastna, M.; Lamb, K. G.

    2016-11-01

    Discontinuous Galerkin methods offer a promising methodology for treating nearly hyperbolic systems such as dispersion-modified shallow water equations in complicated basins. Use of straight-edged triangular elements can lead to the generation of spurious eddies when wave fronts propagate around sharp, re-entrant obstacles such as headlands. While these eddies may be removed by adding strong artificial dissipation (e.g., eddy viscosity), for nearly inviscid simulations that focus on wave phenomena this approach is not reasonable. We demonstrate that the moderate order Discontinuous Galerkin methodology may be extended to curved triangular elements provided that the integral formulations are computed with high-order quadrature and cubature rules. Simulations with the new technique do not exhibit spurious eddy generation in idealized complex domains or real-world basins as exemplified by Pinehurst Lake, Alberta, Canada.

  15. An energy and potential enstrophy conserving scheme for the shallow water equations. [orography effects on atmospheric circulation

    NASA Technical Reports Server (NTRS)

    Arakawa, A.; Lamb, V. R.

    1979-01-01

    A three-dimensional finite difference scheme for the solution of the shallow water momentum equations which accounts for the conservation of potential enstrophy in the flow of a homogeneous incompressible shallow atmosphere over steep topography as well as for total energy conservation is presented. The scheme is derived to be consistent with a reasonable scheme for potential vorticity advection in a long-term integration for a general flow with divergent mass flux. Numerical comparisons of the characteristics of the present potential enstrophy-conserving scheme with those of a scheme that conserves potential enstrophy only for purely horizontal nondivergent flow are presented which demonstrate the reduction of computational noise in the wind field with the enstrophy-conserving scheme and its convergence even in relatively coarse grids.

  16. Fast Averaging for Long- and Short-wave Scaled Equatorial Shallow Water Equations with Coriolis Parameter Deviating from Linearity

    NASA Astrophysics Data System (ADS)

    Dutrifoy, Alexandre

    2015-04-01

    The equatorial shallow water equations at low Froude number form a symmetric hyperbolic system with large terms containing a variable coefficient, the Coriolis parameter f, which depends on the latitude. The limiting behavior of the solutions as the Froude number tends to zero was investigated rigorously a few years ago, using the common approximation that the variations of f with latitude are linear. In that case, the large terms have a peculiar structure, due to special properties of the harmonic oscillator Hamiltonian, which can be exploited to prove strong uniform a priori estimates in adapted functional spaces. It is shown here that these estimates still hold when f deviates from linearity, even though the special properties on which the proofs were based have no obvious generalization. As in the linear case, existence, uniqueness and convergence properties of the solutions corresponding to general unbalanced data are deduced from the estimates.

  17. The effects of the Asselin time filter on numerical solutions to the linearized shallow-water wave equations

    NASA Technical Reports Server (NTRS)

    Schlesinger, R. E.; Johnson, D. R.; Uccellini, L. W.

    1983-01-01

    In the present investigation, a one-dimensional linearized analysis is used to determine the effect of Asselin's (1972) time filter on both the computational stability and phase error of numerical solutions for the shallow water wave equations, in cases with diffusion but without rotation. An attempt has been made to establish the approximate optimal values of the filtering parameter nu for each of the 'lagged', Dufort-Frankel, and Crank-Nicholson diffusion schemes, suppressing the computational wave mode without materially altering the physical wave mode. It is determined that in the presence of diffusion, the optimum filter length depends on whether waves are undergoing significant propagation. When moderate propagation is present, with or without diffusion, the Asselin filter has little effect on the spatial phase lag of the physical mode for the leapfrog advection scheme of the three diffusion schemes considered.

  18. Variational data assimilation with a semi-Lagrangian semi-implicit global shallow-water equation model and its adjoint

    NASA Technical Reports Server (NTRS)

    Li, Y.; Navon, I. M.; Courtier, P.; Gauthier, P.

    1993-01-01

    An adjoint model is developed for variational data assimilation using the 2D semi-Lagrangian semi-implicit (SLSI) shallow-water equation global model of Bates et al. with special attention being paid to the linearization of the interpolation routines. It is demonstrated that with larger time steps the limit of the validity of the tangent linear model will be curtailed due to the interpolations, especially in regions where sharp gradients in the interpolated variables coupled with strong advective wind occur, a synoptic situation common in the high latitudes. This effect is particularly evident near the pole in the Northern Hemisphere during the winter season. Variational data assimilation experiments of 'identical twin' type with observations available only at the end of the assimilation period perform well with this adjoint model. It is confirmed that the computational efficiency of the semi-Lagrangian scheme is preserved during the minimization process, related to the variational data assimilation procedure.

  19. Extension of an explicit finite volume method to large time steps (CFL>1): application to shallow water flows

    NASA Astrophysics Data System (ADS)

    Murillo, J.; García-Navarro, P.; Brufau, P.; Burguete, J.

    2006-01-01

    In this work, the explicit first order upwind scheme is presented under a formalism that enables the extension of the methodology to large time steps. The number of cells in the stencil of the numerical scheme is related to the allowable size of the CFL number for numerical stability. It is shown how to increase both at the same time. The basic idea is proposed for a 1D scalar equation and extended to 1D and 2D non-linear systems with source terms. The importance of the kind of grid used is highlighted and the method is outlined for irregular grids. The good quality of the results is illustrated by means of several examples including shallow water flow test cases. The bed slope source terms are involved in the method through an upwind discretization.

  20. Coupling between shallow water and solute flow equations: analysis and management of source terms in 2D

    NASA Astrophysics Data System (ADS)

    Murillo, J.; Burguete, J.; Brufau, P.; García-Navarro, P.

    2005-09-01

    A two-dimensional model for the simulation of solute transport by convection and diffusion into shallow water flow over variable bottom is presented. It is based on a finite volume method over triangular unstructured grids. A first order upwind technique is applied to solve the flux terms in both the flow and solute equations and the bed slope source terms and a centred discretization is applied to the diffusion and friction terms. The convenience of considering the fully coupled system of equations is indicated and the methodology is well explained. Three options are suggested and compared in order to deal with the diffusion terms. Some comparisons are carried out in order to show the performance in terms of accuracy and computational effort of the different options.

  1. A primal-dual mimetic finite element scheme for the rotating shallow water equations on polygonal spherical meshes

    NASA Astrophysics Data System (ADS)

    Thuburn, John; Cotter, Colin J.

    2015-06-01

    A new numerical method is presented for solving the shallow water equations on a rotating sphere using quasi-uniform polygonal meshes. The method uses special families of finite element function spaces to mimic key mathematical properties of the continuous equations and thereby capture several desirable physical properties related to balance and conservation. The method relies on two novel features. The first is the use of compound finite elements to provide suitable finite element spaces on general polygonal meshes. The second is the use of dual finite element spaces on the dual of the original mesh, along with suitably defined discrete Hodge star operators to map between the primal and dual meshes, enabling the use of a finite volume scheme on the dual mesh to compute potential vorticity fluxes. The resulting method has the same mimetic properties as a finite volume method presented previously, but is more accurate on a number of standard test cases.

  2. On Breaking Waves and Wave-Current Interaction in Shallow Water: a 2DH Finite Element Model

    NASA Astrophysics Data System (ADS)

    Antunes Do Carmo, J. S.; Seabra-Santos, F. J.

    1996-03-01

    A two-dimensional (horizontal plane) coastal and estuarine region model, capable of predicting the combined effects of gravity surface shallow- water waves (shoaling, refraction, diffraction, reflection and breaking), and steady currents, is described and numerical results are compared with those obtained experimentally.Two series of observations within a wave flume and a combined wave-current facility were developed. In the first case, the wave was generated via a hinged paddle located within a deepened section at one end of the channel, as, in the second case, the wave propagating with or against the current was generated by a plunger-type wavemaker; the re-circulating current was introduced via one passing tank connected to a centrifugal pump.Several comparisons for a number of 1D situations and one 2D horizontal plane case are presented.

  3. Middle Cretaceous to Oligocene rise of the Middle American landbridge - documented by south-eastwards younging shallow water carbonates

    NASA Astrophysics Data System (ADS)

    Baumgartner-Mora, Claudia; Baumgartner, Peter O.; Barat, Flore

    2013-04-01

    Basements of Southern Central America are oceanic in origin, including the southern half of the classical "Chortis Block" formed by subduction/accretion mélanges named Mesquito Composite Oceanic Terrane (MCOT). The rise of these oceanic basements into the photic zone and eventual emergence was controlled by convergent, collision tectonics, and/or arc development. In this context, shallow carbonate palaeo-environments were short-lived and formed not only on uplifted basements and arcs, but also on (now accreted) volcanic edifices of Pacific oceanic seamounts. From Northern Nicaragua (NW) to Eastern Panama (SE) we observe a systematic younging of the first shallow water carbonate facies encroaching on basements and/or older deep-water formations: In the Siuna area (NE-Nicaragua) Aptian-Albian shallow water limestones dated by rudists and Orbitolina texana rest unconformably on the Jurassic/Early Cretaceous Siuna Serpentinite Mélange, part of the MCOT. In N-Costa Rica, the assembly of several terranes (Santa Elena Ultramafic Unit, Nicoya Complex s. s., Matambu and Manzanillo Terranes) is overlapped by Late Campanian-Maastrichtian shallow water facies dated by rudists and Larger Foraminifera, such as Pseudorbitoides rutteni, Pseudorbitoides israelski, Sulcoperculina sp. and Sulcoperculina globosa. Reworked Campanian-Maastrichtian shallow water material including Larger Foraminifera was found in the Herradura Promontory (central Pacific coast of Costa Rica). It could be derived from an accreted seamount. No shallow carbonates are known so far from the early Palaeocene. The Tempisque Basin (N-Costa Rica) hosts the Barra Honda carbonate Platform (originally >900 km2) dated as late Palaeocene (Thanetian) by planktonic Foraminifera, 87Sr / 86Sr ratios and Ranikothalia spp. Other late Palaeocene shallow carbonates documented in S-Costa Rica/W-Panama (Quepos, Burica) are interpreted as insular carbonate shoals (atolls?) on now accreted seamounts. To the SE of the S

  4. Analyzing sound speed fluctuations in shallow water from group-velocity versus phase-velocity data representation.

    PubMed

    Roux, Philippe; Kuperman, W A; Cornuelle, Bruce D; Aulanier, Florian; Hodgkiss, W S; Song, Hee Chun

    2013-04-01

    Data collected over more than eight consecutive hours between two source-receiver arrays in a shallow water environment are analyzed through the physics of the waveguide invariant. In particular, the use of vertical arrays on both the source and receiver sides provides source and receiver angles in addition to travel-times associated with a set of eigenray paths in the waveguide. From the travel-times and the source-receiver angles, the eigenrays are projected into a group-velocity versus phase-velocity (Vg-Vp) plot for each acquisition. The time evolution of the Vg-Vp representation over the 8.5-h long experiment is discussed. Group speed fluctuations observed for a set of eigenrays with turning points at different depths in the water column are compared to the Brunt-Väisälä frequency.

  5. Ice berg cracking events as identified from underwater ambient noise measurements in the shallow waters of Ny-Alesund, Arctic

    NASA Astrophysics Data System (ADS)

    Ashokan, M.; Latha, G.; Thirunavukkarasu, A.; Raguraman, G.; Venkatesan, R.

    2016-06-01

    This paper presents the work carried out on the analysis of preliminary underwater ambient noise measurements in the shallow waters of Kongsfjorden fjord, Arctic in the summer season, in which the ice berg cracking noise is identified. In the summer period, the melting of ice cover is fast and hence the ice bergs are free to move and float in the ocean. Underwater ambient noise has been acquired in the Kongsfjorden fjord, Arctic sea on 19th July 2015 at 5 m water depth, where the ocean depth is 50 m. Due to the tensile cracks at the surface of the sea ice by thermal expansion, ice berg calving and bobbing occurred near the experiment site. Analysis of power spectra shows that ice berg calving noise falls in the frequency band 100 Hz-500 Hz and the ice berg bobbing noise falls in the frequency band 200 Hz-400 Hz.

  6. On the advantage of well-balanced schemes for moving-water equilibria of the shallow water equations

    SciTech Connect

    Xing, Yulong; Shu, Chi-wang; Noelle, Sebastian

    2011-01-01

    This note aims at demonstrating the advantage of moving-water well-balanced schemes over still-water well-balanced schemes for the shallow water equations. We concentrate on numerical examples with solutions near a moving-water equilibrium. For such examples, still-water well-balanced methods are not capable of capturing the small perturbations of the moving-water equilibrium and may generate significant spurious oscillations, unless an extremely refined mesh is used. On the other hand, moving-water well-balanced methods perform well in these tests. The numerical examples in this note clearly demonstrate the importance of utilizing moving-water well-balanced methods for solutions near a moving-water equilibrium.

  7. Solitons and integrability for a (2+1)-dimensional generalized variable-coefficient shallow water wave equation

    NASA Astrophysics Data System (ADS)

    Wang, Ya-Le; Gao, Yi-Tian; Jia, Shu-Liang; Lan, Zhong-Zhou; Deng, Gao-Fu; Su, Jing-Jing

    2017-01-01

    Under investigation in this paper is a (2+1)-dimensional generalized variable-coefficient shallow water wave equation which can be reduced to several integrable equations, such as the Korteweg-de Vries (KdV) equation and the Calogero-Bogoyavlenskii-Schiff (CBS) equation. Bilinear forms, Bäcklund transformation, Lax pair and infinite conservation laws are derived based on the binary Bell polynomials. N-soliton solutions are constructed via the Hirota method. Propagation and interaction of the solitons are illustrated graphically: (i) variable coefficients affect the shape of the N-soliton interaction in the scaled space and time coordinates; (ii) positions of the solitons depend on the sign of wave numbers after each interaction; (iii) interaction of the solitons is elastic, i.e. the amplitude, velocity and shape of each soliton remain invariant after each interaction except for a phase shift.

  8. A mass and momentum flux-form high-order discontinuous Galerkin shallow water model on the cubed-sphere

    NASA Astrophysics Data System (ADS)

    Bao, Lei; Nair, Ramachandran D.; Tufo, Henry M.

    2014-08-01

    A well-balanced discontinuous Galerkin (DG) flux-form shallow-water (SW) model on the sphere is developed and compared with a nodal DG SW model cast in the vector-invariant form for accuracy and conservation properties. A second-order diffusion scheme based on the local discontinuous Galerkin (LDG) method is added to the viscous version of the SW model and tested for conservation behaviors. The inviscid flux-form SW model is found to have better conservation of total energy and zonal angular momentum while the vector-invariant form provides better ability of conserving potential enstrophy. The inviscid flux-form tends to generate spurious vorticity but the LDG scheme combined with a well-balanced treatment can effectively eliminate the small-scale noise and generate smooth and accurate results.

  9. Integration of the shallow water equations on the sphere using a vector semi-Lagrangian scheme with a multigrid solver

    NASA Technical Reports Server (NTRS)

    Bates, J. R.; Semazzi, F. H. M.; Higgins, R. W.; Barros, Saulo R. M.

    1990-01-01

    A vector semi-Lagrangian semi-implicit two-time-level finite-difference integration scheme for the shallow water equations on the sphere is presented. A C-grid is used for the spatial differencing. The trajectory-centered discretization of the momentum equation in vector form eliminates pole problems and, at comparable cost, gives greater accuracy than a previous semi-Lagrangian finite-difference scheme which used a rotated spherical coordinate system. In terms of the insensitivity of the results to increasing timestep, the new scheme is as successful as recent spectral semi-Lagrangian schemes. In addition, the use of a multigrid method for solving the elliptic equation for the geopotential allows efficient integration with an operation count which, at high resolution, is of lower order than in the case of the spectral models. The properties of the new scheme should allow finite-difference models to compete with spectral models more effectively than has previously been possible.

  10. Inverse algorithms for 2D shallow water equations in presence of wet dry fronts: Application to flood plain dynamics

    NASA Astrophysics Data System (ADS)

    Monnier, J.; Couderc, F.; Dartus, D.; Larnier, K.; Madec, R.; Vila, J.-P.

    2016-11-01

    The 2D shallow water equations adequately model some geophysical flows with wet-dry fronts (e.g. flood plain or tidal flows); nevertheless deriving accurate, robust and conservative numerical schemes for dynamic wet-dry fronts over complex topographies remains a challenge. Furthermore for these flows, data are generally complex, multi-scale and uncertain. Robust variational inverse algorithms, providing sensitivity maps and data assimilation processes may contribute to breakthrough shallow wet-dry front dynamics modelling. The present study aims at deriving an accurate, positive and stable finite volume scheme in presence of dynamic wet-dry fronts, and some corresponding inverse computational algorithms (variational approach). The schemes and algorithms are assessed on classical and original benchmarks plus a real flood plain test case (Lèze river, France). Original sensitivity maps with respect to the (friction, topography) pair are performed and discussed. The identification of inflow discharges (time series) or friction coefficients (spatially distributed parameters) demonstrate the algorithms efficiency.

  11. INVERSE ESTIMATION OF BED ROUGHNESS COEFFICIENTS IN OPEN-CHANNELS WITH FLOOD PLAINS BY USING ADJOINT SHALLOW-WATER MODEL

    NASA Astrophysics Data System (ADS)

    Yoshida, Keisuke

    This study describes the methodology on an inverse estimation of the bed roughness coefficients in open-channels with flood plains. The coefficients are identified by an adjoint shallow-water model and an optimal control theory. Several twin experiments were carried out with the synthetic data in order to validate the method. The data assimilated consists of values of the water level and depth-averaged velocity. The results showed that the coefficients can be accurately predicted with the velocity data, while the estimation fails with the water level data. This is because the cross-sectionally distributed bed roughness does not always influence the lateral profile of the water level, but the local velocity field. Namely, the relation between the lateral profile of the water level and the bed roughness turns out to be non-unique in open-channels with flood plains.

  12. 50 CFR 18.94 - Pacific walrus (Alaska).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 8 2011-10-01 2011-10-01 false Pacific walrus (Alaska). 18.94 Section 18... Marine Mammal Species § 18.94 Pacific walrus (Alaska). (a) Pursuant to sections 101(a)(3)(A) 103, and 109... walrus (Odobenus rosmarus) in waters or on lands subject to the jurisdiction of the State of Alaska,...

  13. 50 CFR 18.94 - Pacific walrus (Alaska).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 9 2013-10-01 2013-10-01 false Pacific walrus (Alaska). 18.94 Section 18... Marine Mammal Species § 18.94 Pacific walrus (Alaska). (a) Pursuant to sections 101(a)(3)(A) 103, and 109... walrus (Odobenus rosmarus) in waters or on lands subject to the jurisdiction of the State of Alaska,...

  14. 50 CFR 18.94 - Pacific walrus (Alaska).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 9 2012-10-01 2012-10-01 false Pacific walrus (Alaska). 18.94 Section 18... Marine Mammal Species § 18.94 Pacific walrus (Alaska). (a) Pursuant to sections 101(a)(3)(A) 103, and 109... walrus (Odobenus rosmarus) in waters or on lands subject to the jurisdiction of the State of Alaska,...

  15. Biomarkers of PAH exposure in an intertidal fish species from Prince William Sound, Alaska: 2004-2005.

    PubMed

    Huggett, Robert J; Neff, Jerry M; Stegeman, John J; Woodin, Bruce; Parker, Keith R; Brown, John S

    2006-10-15

    Polycyclic aromatic hydrocarbon (PAH) exposure biomarkers were measured in high cockscomb prickleback (Anoplarchus purpurescens) fish collected from both previously oiled and unoiled shore in Prince William Sound (PWS), Alaska, to test the hypothesis that fish living in the nearshore environment of the sound were no longer being exposed to PAH from the Exxon Valdez oil spill. Pricklebacks spend their entire lives in the intertidal zone of rocky shores with short-term movements during feeding and breeding restricted to an area of about 15 meters in diameter. Fish were assayed for the PAH exposure biomarkers, bile fluorescent aromatic compounds (FAC), and liver ethoxyresorufin O-deethylase (EROD) activity (a measure of cytochrome P450 1A (CYP1A) monooxygenase activity). Bile FAC concentrations and EROD activities were low and not significantly different in fish from previously oiled and unoiled sites. The similar low EROD activity and bile FAC concentrations in fish from oiled and unoiled shores, supports the hypothesis that these low-level biomarker responses were not caused by exposure of the fish to residues of the spilled oil.

  16. Collecting single and multichannel seismic-reflection data in shallow water near Aberdeen Proving Ground, Chesapeake Bay, Maryland

    SciTech Connect

    Haeni, F.P.; Banks, W.L.; Versteeg, R.J.

    1995-12-31

    In August and September 1994, single- and multi-channel seismic-reflection data were collected by the U.S. Geological Survey (USGS), in cooperation with the U.S. Army and the U.S. Army Corps of Engineers (COE), to support a regional hydrogeologic framework study at Aberdeen Proving Ground (APG), Maryland. Data were collected in Chesapeake Bay, as well as in the Bush, Gunpowder, and Sassafras Rivers, which are tributaries to Chesapeake Bay. Data were collected along the shoreline in very shallow water, usually less than 1 m. Approximately 100 km of single-channel seismic-reflection data were collected using a water gun and an electromechanical plate as sound sources; about 50 percent of these data contained usable geologic information. A prominent channel in the Quaternary sediments at a depth of 61 m is clearly evident, and the depth to bedrock ranges from approximately 184 to 223 m. Approximately 14 km of multi-channel data were collected in the Gunpowder and Bush Rivers and in Chesapeake Bay; about 40 percent of these data showed subsurface reflectors, often in small, discontinuous segments. Data were processed using established processing techniques. Numerous reflectors were present in the data that were continuous over long distances. The multi-channel data contained more detail and significantly less noise than the single-channel data. The quality and continuity of the single- and multi-channel data were best in shallow water (less than 1 m) where the presence of gassing organic sediments was at a minimum.

  17. Multiple Suppression and Imaging of Marine Seismic Data from The Shallow Water Area in Southern East China Sea Shelf Basin

    NASA Astrophysics Data System (ADS)

    Shi, J.; Luan, X.; Yang, C.

    2015-12-01

    Neither surface-related multiple elimination(SRME) nor predictive de-convolution method is effective to suppress the multiple of marine seismic data from the shallow water area. The former method needs the accurate reflection of seafloor, which is mixed with the direct wave in the near offset range. The other one could probably lose the primary wave when applied to the shallow water seismic data. We introduced the new method: deterministic water-layer de-multiple method (DWD) which is capable for the poor extrapolate result of near-offset traces. Firstly, the data shifts as downward continuation in tau-p domain with a water-layer period and the multiple model will be obtained. Then, the original seismic subtracts adaptively with the multiple model. Finally, we would get the de-multiple data after inverse tau-p transform. Marine seismic real data is from southern part of East China Sea Shelf Basin. This area has become the potential target for marine hydrocarbon exploration, it is located in the junction of the Eurasian plate pacific plate and Indian plate. Because the average water depth is less than 100 meters, seismic data contains abundant of multiple, especially the surface-related multiple. As a result it is difficult to distinguish the strata structure clearly. We used DWD approach to remove the water-layer multiple, cut off the seafloor reflection events and then suppressed the residual surface-related multiple by the traditional SRME. At last , the radon transform was applied to eliminate the multiple with long period . With these steps, we suppressed the multiple of marine seismic data from this area effectively. After multiple is removed , we acquired more accurate velocity to build the velocity model of migration. With the pre-stack migration technique, reflections from each geological period are shown clearly in the seismic section. This work was supported by the National Science Foundation of China(grant no. 41476053).

  18. Strangelove Ocean and Deposition of Unusual Shallow-Water Carbonates After the End-Permian Mass Extinction

    NASA Technical Reports Server (NTRS)

    Rampino, Michael R.; Caldeira, Ken

    2003-01-01

    The severe mass extinction of marine and terrestrial organisms at the end of the Permian Period (approx. 251 Ma) was accompanied by a rapid negative excursion of approx. 3 to 4 per mil in the carbon-isotope ratio of the global surface oceans and atmosphere that persisted for some 500,000 into the Early Triassic. Simulations with an ocean-atmosphere/carbon-cycle model suggest that the isotope excursion can be explained by collapse of ocean primary productivity (a Strangelove Ocean) and changes in the delivery and cycling of carbon in the ocean and on land. Model results also suggest that perturbations of the global carbon cycle resulting from the extinctions led to short-term fluctuations in atmospheric pCO2 and ocean carbonate deposition, and to a long-term (>1 Ma) decrease in sedimentary burial of organic carbon in the Triassic. Deposition of calcium carbonate is a major sink of river-derived ocean alkalinity and for CO2 from the ocean/atmosphere system. The end of the Permian was marked by extinction of most calcium carbonate secreting organisms. Therefore, the reduction of carbonate accumulation made the oceans vulnerable to a build-up of alkalinity and related fluctuations in atmospheric CO2. Our model results suggest that an increase in ocean carbonate-ion concentration should cause increased carbonate accumulation rates in shallow-water settings. After the end-Permian extinctions, early Triassic shallow-water sediments show an abundance of abiogenic and microbial carbonates that removed CaCO3 from the ocean and may have prevented a full 'ocean-alkalinity crisis' from developing.

  19. Influence of open ocean nitrogen supply on the skeletal δ15N of modern shallow-water scleractinian corals

    NASA Astrophysics Data System (ADS)

    Wang, Xingchen T.; Sigman, Daniel M.; Cohen, Anne L.; Sinclair, Daniel J.; Sherrell, Robert M.; Cobb, Kim M.; Erler, Dirk V.; Stolarski, Jarosław; Kitahara, Marcelo V.; Ren, Haojia

    2016-05-01

    The isotopic composition of skeleton-bound organic nitrogen in shallow-water scleractinian corals (hereafter, CS-δ15N) is an emerging tool for studying the marine nitrogen cycle in the past. The CS-δ15N has been shown to reflect the δ15N of nitrogen (N) sources to corals, with most applications to date focusing on the anthropogenic/terrestrial N inputs to reef environments. However, many coral reefs receive their primary N sources from the open ocean, and the CS-δ15N of these corals may provide information on past changes in the open ocean regional and global N cycle. Using a recently developed persulfate/denitrifier-based method, we measured CS-δ15N in modern shallow-water scleractinian corals from 8 sites proximal to the open ocean. At sites with low open ocean surface nitrate concentrations typical of the subtropics and tropics, measured CS-δ15N variation on seasonal and annual timescales is most often less than 2‰. In contrast, a broad range in CS-δ15N (of ∼10‰) is measured across these sites, with a strong correlation between CS-δ15N and the δ15N of the deep nitrate supply to the surface waters near the reefs. While CS-δ15N can be affected by other N sources as well and can vary in response to local reef conditions as well as coral/symbiont physiological changes, this survey indicates that, when considering corals proximal to the open ocean, the δ15N of the subsurface nitrate supply to surface waters drives most of the CS-δ15N variation across the global ocean. Thus, CS-δ15N is a promising proxy for reconstructing the open ocean N cycle in the past.

  20. Magnetostratigraphy of Mesozoic shallow-water carbonates: Preliminary results from the Middle Jurassic of the Paris basin

    SciTech Connect

    Aissaoui, D.M.; Kirschvink, J.L. )

    1991-03-01

    The use of sedimentary paleomagnetism has enhanced greatly our understanding of the timing of deposition and diagenesis of Cenozoic platform and reefal carbonates. Its application to similar but older deposits will have direct implications for economic exploration and development. The authors report here preliminary paleomagnetic results from the Middle Jurassic limestones of the Paris basin (France). The samples consist mainly of bioclastic and oolitic limestones deposited in ancient counterpart of the shallow-water environments of the Bahama platform. The Jurassic samples are stable to progressive, incremental demagnetization and exhibit magnetization patterns identical to Cenozoic rocks from the Bahama platform or Mururoa Atoll. The natural remanent magnetization of these limestones is weak and comprised between 7.7 x 10{sup {minus}9} to 1.8 x 10{sup {minus}8} AM{sup 2}/kg. Magnetic components of both normal and reversed polarity are observed. Paired isothermal remanent magnetization (IRM) and alternating field demagnetization experiments show that most of the remanence is lost between 20 and 45 mT, which is typical of single-domain biogenic magnetite or maghemite. The ratio of IRM at H{sub RG} to the saturation IRM ranges from 35 to 42% indicating a moderate to low interparticle interaction. This is confirmed by the anhysteretic remanent magnetization as compared with intact, freeze-dried cells of magnetotactic bacteria and chiton teeth. Magnetic minerals extracted from the Jurassic samples are examined to further confirm the occurrence of SD magnetite within the Middle Jurassic limestones of the Paris basin. The preliminary results suggest that the strata should be good for the paleomagnetic investigation of Mesozoic shallow-water carbonates.

  1. Investigating phenology of larval fishes in St. Louis River estuary shallow water habitats

    EPA Science Inventory

    As part of the development of an early detection monitoring strategy for non-native fishes, larval fish surveys have been conducted since 2012 in the St. Louis River estuary. Survey data demonstrates there is considerable variability in fish abundance and species assemblages acro...

  2. Shallow-water zoantharians (Cnidaria, Hexacorallia) from the Central Indo-Pacific

    PubMed Central

    Reimer, James D.; Poliseno, Angelo; Hoeksema, Bert W.

    2014-01-01

    Abstract Despite the Central Indo-Pacific (CIP) and the Indonesian Archipelago being a well-known region of coral reef biodiversity, particularly in the ‘Coral Triangle’, little published information is available on its zoantharians (Cnidaria: Hexacorallia: Zoantharia). In order to provide a basis for future research on the Indo-Pacific zoantharian fauna and facilitate comparisons between more well-studied regions such as Japan and the Great Barrier Reef, this report deals with CIP zoantharian specimens in the Naturalis collection in Leiden, the Netherlands; 106 specimens were placed into 24 morpho-species and were supplemented with 88 in situ photographic records from Indonesia, the Philippines, and Papua New Guinea. At least nine morpho-species are likely to be undescribed species, indicating that the region needs more research in order to properly understand zoantharian diversity within the CIP. The Naturalis’ zoantharian specimens are listed by species, as well as all relevant collection information, and in situ images are provided to aid in future studies on zoantharians in the CIP. PMID:25349499

  3. Shallow-water zoantharians (Cnidaria, Hexacorallia) from the Central Indo-Pacific.

    PubMed

    Reimer, James D; Poliseno, Angelo; Hoeksema, Bert W

    2014-01-01

    Despite the Central Indo-Pacific (CIP) and the Indonesian Archipelago being a well-known region of coral reef biodiversity, particularly in the 'Coral Triangle', little published information is available on its zoantharians (Cnidaria: Hexacorallia: Zoantharia). In order to provide a basis for future research on the Indo-Pacific zoantharian fauna and facilitate comparisons between more well-studied regions such as Japan and the Great Barrier Reef, this report deals with CIP zoantharian specimens in the Naturalis collection in Leiden, the Netherlands; 106 specimens were placed into 24 morpho-species and were supplemented with 88 in situ photographic records from Indonesia, the Philippines, and Papua New Guinea. At least nine morpho-species are likely to be undescribed species, indicating that the region needs more research in order to properly understand zoantharian diversity within the CIP. The Naturalis' zoantharian specimens are listed by species, as well as all relevant collection information, and in situ images are provided to aid in future studies on zoantharians in the CIP.

  4. Seabirds in Alaska

    USGS Publications Warehouse

    Hatch, Scott A.; Piatt, John F.

    1995-01-01

    Techniques for monitoring seabird populations vary according to habitat types and the breeding behavior of individual species (Hatch and Hatch 1978, 1989; Byrd et al. 1983). An affordable monitoring program can include but a few of the 1,300 seabird colonies identified in Alaska, and since the mid-1970's, monitoring effotrts have emphasized a small selection of surface-feeding and diving species, primarily kittiwakes (Rissa spp.) and murres (Uria spp.). Little or no information on trends is available for other seabirds (Hatch 1993a). The existing monitoring program occurs largely on sites within the Alaska Maritime National Wildlife Refuge, which was established primarily for the conservation of marine birds. Data are collected by refuge staff, other state and federal agencies, private organizations, university faculty, and students.

  5. Travelling-wave solutions of a weakly nonlinear two-dimensional higher-order Kadomtsev-Petviashvili dynamical equation for dispersive shallow-water waves

    NASA Astrophysics Data System (ADS)

    Seadawy, Aly R.

    2017-01-01

    The propagation of three-dimensional nonlinear irrotational flow of an inviscid and incompressible fluid of the long waves in dispersive shallow-water approximation is analyzed. The problem formulation of the long waves in dispersive shallow-water approximation lead to fifth-order Kadomtsev-Petviashvili (KP) dynamical equation by applying the reductive perturbation theory. By using an extended auxiliary equation method, the solitary travelling-wave solutions of the two-dimensional nonlinear fifth-order KP dynamical equation are derived. An analytical as well as a numerical solution of the two-dimensional nonlinear KP equation are obtained and analyzed with the effects of external pressure flow.

  6. Origins of chromite and magnetite in sedimentary rocks deposited in a shallow water environment in the 3.2 Ga Moodies Group, South Africa

    NASA Astrophysics Data System (ADS)

    Otake, T.; Sakamoto, Y.; Itoh, S.; Yurimoto, H.; Kakegawa, T.

    2012-12-01

    *Otake, T. totake@eng.hokudai.ac.jp Div. of Sustainable Resources Engineering, Hokkaido Univ., Sapporo, Japan Sakamoto, Y. yu.sakamoto12@gmail.com Dep. of Earth Science, Tohoku Univ., Sendai, Japan Itoh, S. sitoh@ep.sci.hokudai.ac.jp Dep. of Natural History Sciences, Hokkaido Univ., Sapporo, Japan Yurimoto. H. yuri@ep.sci.hokudai.ac.jp Dep. of Natural History Sciences, Hokkaido Univ., Sapporo, Japan Kakegawa, T. kakegawa@m.tohoku.ac.jp Dep. of Earth Science, Tohoku Univ., Sendai, Japan Geochemical data from ferruginous chemical sedimentary rocks (e.g., Banded Iron Formation: BIF) have been used to reconstruct the surface environments of early Earth. However, only a few studies have investigated the geochemical characteristics of BIFs deposited in a shallow water environment during the Archean, which may have differed from those deposited in a deep water environment. Therefore, we investigated geological, petrographic and geochemical characteristics of ferruginous rocks deposited in a shallow water environment in the Moodies group, in the Barberton Greenstone Belt, South Africa. We obtained ferruginous rock samples in the Moodies group from both an outcrop and underground gold mine, and compared the characteristics of these samples. The 70 sedimentary rock samples were divided into groups based on the dominant Fe minerals they contain: Hematite-rich jaspilite (HM group), Magnetite-rich iron formation/shale/sandstone (MT group), and Siderite-rich sandstone (SD group). Samples in the HM group are predominantly composed of fine-grained quartz (< 20 μm) and hematite (< 5 μm), which are interpreted to be chemical precipitates. Samples in the MT group contain quartz, magnetite, siderite, ankerite, chlorite, biotite and chromite. The grain size of magnetite is much larger (20-150 μm) than that of hematite in the HM group. The magnetite is interpreted as a secondary mineral transformed from hematite during early diagenesis. Results of in situ oxygen isotope analysis by

  7. Arsenic metabolism by microbial communities from an arsenic-rich shallow-water hydrothermal system in Ambitle Island, Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Ruiz Chancho, M.; Pichler, T.; Amend, J. P.; Akerman, N. H.

    2011-12-01

    Arsenic, although toxic, is used as an energy source by certain microbes, some of which can catalyse the reduction of arsenate by using different electron donors, while others oxidize arsenite with oxygen or nitrate as electron acceptors. The marine shallow-water hydrothermal system in Tutum Bay, Ambitle Island, Papua New Guinea is ideal for investigating the metabolism of microbes involved in arsenic cycling, because there hydrothermal vents discharge fluids with arsenite concentrations as high as 950 μg/L. Vent fluids are hot (˜100°C), slightly acidic (pH˜6) and reducing. Upon mixing with colder and oxygen-rich seawater the fluid chemistry changes rapidly within a few meters from the hydrothermal source. The objective of this work was to study arsenic metabolism due to microbial activity in Tutum Bay. Sediments collected at 7.5 and 30 m along a transect beginning at a hydrothermal vent were used as inocula in the microbial culturing experiments. Media were designed using chemical analyses of the hydrothermal fluids. Following culture experiments, arsenic species identification and quantification were performed for the growth media with HPLC-ICP(HR)MS, using anion exchange and reversed phase chromatography. Quality control included mass balance calculations and spiking experiments. A fast reduction of arsenate to arsenite was observed in the first 24 hours leading to the conclusion that the microbial communities were capable of reducing arsenic. However, mass balance calculations revealed that more than 30% of the arsenic had been transformed to one or more unknown species, which could not be detected by ion exchange chromatography. The addition of peroxide combined with reversed phase chromatography revealed the presence of several unknown species. Following the addition of peroxide some of the unknown species were identified to be thio-arsenic compounds, because they were oxidized to their oxo-analogues. Nevertheless, a significant fraction of unknown

  8. Assessment of resource selection models to predict occurrence of five juvenile flatfish species (Pleuronectidae) over the continental shelf in the western Gulf of Alaska

    NASA Astrophysics Data System (ADS)

    Wilson, Matthew T.; Mier, Kathryn L.; Cooper, Dan W.

    2016-05-01

    According to the nursery size hypothesis, flatfish recruitment is constrained by nursery area. Thus, if resource selection models can be shown to accurately predict the location and geographic extent of flatfish nursery areas, they will become important tools in the management and study of flatfish population dynamics. We demonstrate that some resource selection models derived previously to predict the presence and absence of juvenile flatfishes near shore were applicable to the broader continental shelf. For other age-species groups, derivation of new models for the continental shelf was necessary. Our study was conducted in the western Gulf of Alaska (GoA) during October 2011 on four groups of age-0 juvenile flatfishes: Pacific halibut (Hippoglossus stenolepis), arrowtooth flounder (Atheresthes stomias), northern rock sole (Lepidopsetta polyxystra), and flathead sole (Hippoglossoides elassodon); and three groups of age-1 juvenile flatfishes: northern rock sole, flathead sole, and yellowfin sole (Limanda aspera). Sampling occurred at 33 sites across the continental shelf. Fish were collected using a 3-m beam trawl, and a midwater trawl. Environmental data were collected on sediment composition and water temperature and depth. Many of the age-species groups co-occurred in the Shumagin and Barnabus sea valleys; however, age-0 arrowtooth flounder occurred at more locations than other juveniles, perhaps due to a relatively broad tolerance of environmental conditions and to the utilization of midwater habitat. Thus, the large nursery area of arrowtooth flounder may be one reason why they are currently the most abundant GoA flatfish. In fact, among all species, mean recruitment at age 3 increased with the percent occurrence of age-0 juveniles at the 33 sites, a proxy for relative nursery area, in accordance with the nursery size hypothesis, suggesting that mean recruitment among GoA flatfishes is structured by nursery size.

  9. Varunaivibrio sulfuroxidans gen. nov., sp. nov., a facultatively chemolithoautotrophic, mesophilic alphaproteobacterium from a shallow-water gas vent at Tor Caldara, Tyrrhenian Sea.

    PubMed

    Patwardhan, Sushmita; Vetriani, Costantino

    2016-09-01

    A mesophilic, facultatively anaerobic, facultatively chemolithoautotrophic bacterium, designated strain TC8T, was isolated from a sulfidic shallow-water marine gas vent located at Tor Caldara, in the Tyrrhenian Sea, Italy. Cells were Gram-stain-negative curved rods with one or more polar flagella. Cells were approximately 1-1.5 µm in length and 0.6 µm in width. Strain TC8T grew between 20 and 35 °C (optimum 30 °C), with between 5 and 45 g NaCl l-1 (optimum 15-20 g l-1) and between pH 4.5 and 8.5 (optimum pH 6.0-7.0). The generation time under optimal conditions was 8 h. Strain TC8T was a facultative chemolithoautotroph also capable of using organic substrates as electron donors and carbon sources. Chemolithoautotrophic growth occurred with sulfur and thiosulfate as the electron donors, CO2 as the carbon source, and nitrate, oxygen (5 %, v/v) and ferric iron as the electron acceptors. Chemoorganoheterotrophic growth occurred with tryptone, peptone, Casamino acids, pyruvate and glycerol as substrates, while chemolithoherotrophic growth occurred with d(+)-glucose, sucrose, yeast extract, acetate, lactate, citrate and l-glutamine. The G+C content of the genomic DNA was 59.9 mol%. Phylogenetic analysis of the 16S rRNA gene sequence of strain TC8T showed that this organism formed a lineage within the family Rhodospirillaceae, which branched separately from the two closest relatives, Magnetovibrio blakemoreiMV1T (91.25 % similarity) and Magnetospira thiophilaMMS-1T (90.13 %). Based on phylogenetic, physiological and chemotaxonomic characteristics, it is proposed that the organism represents a novel species of a new genus within the family Rhodospirillaceae,Varunaivibrio sulfuroxidans gen. nov., sp. nov. The type strain of Varunaivibrio sulfuroxidans is TC8T (=DSM 101688T=JCM 31027T).

  10. Distribution and diversity of sulfur-oxidizing Thiomicrospira spp. at a shallow-water hydrothermal vent in the Aegean Sea (Milos, Greece).

    PubMed

    Brinkhoff, T; Sievert, S M; Kuever, J; Muyzer, G

    1999-09-01

    A shallow-water hydrothermal vent system in the Aegean Sea close to the island of Milos (Greece) was chosen to study the diversity and distribution of the chemolithoautotrophic sulfur-oxidizing bacterium Thiomicrospira. Cell numbers in samples from different regions around a solitary vent decreased toward the center of the vent (horizontal distribution), as well as with depth (vertical distribution), corresponding to an increase in temperature (from ca. 25 to 60 degrees C) and a decrease in pH (from ca. pH 7 to 5). Thiomicrospira was one of the most abundant culturable sulfur oxidizers and was even dominant in one region. Phylogenetic analysis of Thiomicrospira spp. present in the highest most-probable-number (MPN) dilutions revealed that most of the obtained sequences grouped in two new closely related clusters within the Thiomicrospira branch. Two different new isolates, i.e., Milos-T1 and Milos-T2, were obtained from high-dilution (10(-5)) enrichments. Phylogenetic analysis indicated that isolate Milos-T1 is related to the recently described Thiomicrospira kuenenii and Hydrogenovibrio marinus, whereas isolate Milos-T2 grouped with the MPN sequences of cluster 2. The predominance of strain Milos-T2 was indicated by its identification in several environmental samples by hybridization analysis of denaturing gradient gel electrophoresis (DGGE) patterns and by sequencing of one of the corresponding bands, i.e., ML-1, from the DGGE gel. The results shown in this paper support earlier indications that Thiomicrospira species are important members of hydrothermal vent communities.

  11. Snailfishes of the Careproctus rastrinus complex (Liparidae): redescriptions of seven species in the North Pacific Ocean region, with the description of a new species from the Beaufort Sea.

    PubMed

    Orr, James Wilder; Kai, Yoshiaki; Nakabo, Tetsuji

    2015-09-16

    Herein we review and recognize as valid all previously described species of the Careproctus rastrinus complex based on morphological evidence, provide diagnoses and descriptions of all species, describe a new species from the Beaufort Sea, and address the misapplication of several names throughout the area. In particular, the name C. rastrinus is restricted to populations of the western Pacific and is known conclusively only from the Sea of Okhotsk. Careproctus acanthodes, from the Sea of Japan and Sea of Okhotsk, and C. pellucidus, from the Pacific Ocean side of northern Japan, are resurrected from synonymy with C. rastrinus. Populations of the eastern Pacific previously routinely identified as C. rastrinus are recognized under two names: C. scottae, a name that is applied to deeper water Bering Sea, Aleutian Islands, and eastern Pacific populations having a postorbital pore, and Careproctus phasma, applied to shallow water populations of the Bering Sea and Gulf of Alaska lacking a postorbital pore. Although we consider Careproctus spectrum valid, the species has been routinely misidentified and is presently known only from the type series. Careproctus lerikimae is a new species described from the Beaufort Sea, diagnosed from other species of the C. rastrinus complex by the absence of the postorbital pore and higher median fin and vertebral counts.

  12. [Principal stages in the Cenozoic diversification of shallow-water molluscan faunas in the North Pacific].

    PubMed

    Kafanov, A I

    2006-01-01

    Cluster analysis of bivalve species recorded in Cenozoic deposits in Sakhalin Island, western Kamchatka, Hokkaido, and California was used to determine geological age of the modem North Pacific biogeographic region and its constituent subregions (Japan-Mandchurian, Beringian, and Oregon-Sitkan). The North Pacific region developed during the Paleogene-Neogene transition due to Drake Passage opening to deep-water movement, formation of the deep-water Antarctic Circumpolar Current, and the change in climate from greenhouse to psychospheric. Differentiation of the three subregions within the North Pacific Region seems to have occurred in late Miocene-early Pliocene, about 5.6 millions years ago and was probably due to the flooding of the Bering Land Bridge and development of the present configuration of circulation in the North Pacific. In the Northwest Pacific, during Paleogene and early Neogene, the faunal diversification occurred more rapidly and was more extensive than in the Northeast Pacific.

  13. Benthic Trophic Interactions in an Antarctic Shallow Water Ecosystem Affected by Recent Glacier Retreat

    PubMed Central

    Pasotti, Francesca; Saravia, Leonardo Ariel; De Troch, Marleen; Tarantelli, Maria Soledad; Sahade, Ricardo; Vanreusel, Ann

    2015-01-01

    The western Antarctic Peninsula is experiencing strong environmental changes as a consequence of ongoing regional warming. Glaciers in the area are retreating rapidly and increased sediment-laden meltwater runoff threatens the benthic biodiversity at shallow depths. We identified three sites with a distinct glacier-retreat related history and different levels of glacial influence in the inner part of Potter Cove (King George Island, South Shetland Islands), a fjord-like embayment impacted since the 1950s by a tidewater glacier retreat. We compared the soft sediment meio- and macrofauna isotopic niche widths (δ13C and δ15N stable isotope analysis) at the three sites to investigate possible glacier retreat-related influences on benthic trophic interactions. The isotopic niches were locally shaped by the different degrees of glacier retreat-related disturbance within the Cove. Wider isotopic niche widths were found at the site that has become ice-free most recently, and narrower niches at the older ice-free sites. At an intermediate state of glacier retreat-related disturbance (e.g. via ice-growler scouring) species with different strategies could settle. The site at the earliest stage of post-retreat development was characterized by an assemblage with lower trophic redundancy. Generally, the isotopic niche widths increased with increasing size spectra of organisms within the community, excepting the youngest assemblage, where the pioneer colonizer meiofauna size class displayed the highest isotopic niche width. Meiofauna at all sites generally occupied positions in the isotopic space that suggested a detrital-pool food source and/or the presence of predatory taxa. In general ice scour and glacial impact appeared to play a two-fold role within the Cove: i) either stimulating trophic diversity by allowing continuous re-colonization of meiofaunal species or, ii) over time driving the benthic assemblages into a more compact trophic structure with increased

  14. Benthic Trophic Interactions in an Antarctic Shallow Water Ecosystem Affected by Recent Glacier Retreat.

    PubMed

    Pasotti, Francesca; Saravia, Leonardo Ariel; De Troch, Marleen; Tarantelli, Maria Soledad; Sahade, Ricardo; Vanreusel, Ann

    2015-01-01

    The western Antarctic Peninsula is experiencing strong environmental changes as a consequence of ongoing regional warming. Glaciers in the area are retreating rapidly and increased sediment-laden meltwater runoff threatens the benthic biodiversity at shallow depths. We identified three sites with a distinct glacier-retreat related history and different levels of glacial influence in the inner part of Potter Cove (King George Island, South Shetland Islands), a fjord-like embayment impacted since the 1950s by a tidewater glacier retreat. We compared the soft sediment meio- and macrofauna isotopic niche widths (δ13C and δ15N stable isotope analysis) at the three sites to investigate possible glacier retreat-related influences on benthic trophic interactions. The isotopic niches were locally shaped by the different degrees of glacier retreat-related disturbance within the Cove. Wider isotopic niche widths were found at the site that has become ice-free most recently, and narrower niches at the older ice-free sites. At an intermediate state of glacier retreat-related disturbance (e.g. via ice-growler scouring) species with different strategies could settle. The site at the earliest stage of post-retreat development was characterized by an assemblage with lower trophic redundancy. Generally, the isotopic niche widths increased with increasing size spectra of organisms within the community, excepting the youngest assemblage, where the pioneer colonizer meiofauna size class displayed the highest isotopic niche width. Meiofauna at all sites generally occupied positions in the isotopic space that suggested a detrital-pool food source and/or the presence of predatory taxa. In general ice scour and glacial impact appeared to play a two-fold role within the Cove: i) either stimulating trophic diversity by allowing continuous re-colonization of meiofaunal species or, ii) over time driving the benthic assemblages into a more compact trophic structure with increased

  15. A depth-averaged 2-D shallow water model for breaking and non-breaking long waves affected by rigid vegetation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper presents a depth-averaged two-dimensional shallow water model for simulating long waves in vegetated water bodies under breaking and non-breaking conditions. The effects of rigid vegetation are modelled in the form of drag and inertia forces as sink terms in the momentum equations. The dr...

  16. Diversity of Total Bacterial Communities and Chemoautotrophic Populations in Sulfur-Rich Sediments of Shallow-Water Hydrothermal Vents off Kueishan Island, Taiwan.

    PubMed

    Wang, Li; Cheung, Man Kit; Liu, Rulong; Wong, Chong Kim; Kwan, Hoi Shan; Hwang, Jiang-Shiou

    2017-04-01

    Shallow-water hydrothermal vents (HTVs) are an ecologically important habitat with a geographic origin similar to that of deep-sea HTVs. Studies on shallow-water HTVs have not only facilitated understanding of the influences of vents on local ecosystems but also helped to extend the knowledge on deep-sea vents. In this study, the diversity of bacterial communities in the sediments of shallow-water HTVs off Kueishan Island, Taiwan, was investigated by examining the 16S ribosomal RNA gene as well as key functional genes involved in chemoautotrophic carbon fixation (aclB, cbbL and cbbM). In the vent area, Sulfurovum and Sulfurimonas of Epsilonproteobacteria appeared to dominate the benthic bacterial community. Results of aclB gene analysis also suggested involvement of these bacteria in carbon fixation using the reductive tricarboxylic acid (rTCA) cycle. Analysis of the cbbM gene showed that Alphaproteobacterial members such as the purple non-sulfur bacteria were the major chemoautotrophic bacteria involving in carbon fixation via the Calvin-Benson-Bassham (CBB) cycle. However, they only accounted for <2% of the total bacterial community in the vent area. These findings suggest that the rTCA cycle is the major chemoautotrophic carbon fixation pathway in sediments of the shallow-water HTVs off Kueishan Island.

  17. Carbon-Isotope Stratigraphy Of A Paleogene Pacific Ocean Guyot And The Response Of The Shallow-Water Carbonate Factory To The PETM

    NASA Astrophysics Data System (ADS)

    Robinson, S. A.

    2009-12-01

    The shallow-water carbonate platforms found on many Pacific guyots potentially provide ‘dipsticks’ for shallow-water environmental and climatic conditions unhindered by the influence of clastic input. They thus represent ideal sites at which to assess the extent to which past changes in surface-ocean physical and chemical conditions (e.g. temperature, nutrification, pH) affected the sustainability of shallow-water carbonate producers. The PETM and other Paleogene hyperthermal events are associated with major carbon-cycle perturbations and deep-sea carbonate dissolution, yet the effect in shallow-water carbonate environments is more poorly constrained. This is in part due to complications arising from variations in sea level causing major facies changes in many coastal shelf settings and also difficulties in providing robust age controls for some carbonate platforms. The basaltic edifice of Limalok Guyot (ODP Site 871) in the southwest Pacific Ocean was flooded in the late Paleocene and accumulated shallow-water carbonate sediments until the middle Eocene, when the platform drowned and was buried under a pelagic cap. A new carbon-isotope stratigraphy for the platform carbonates will be presented which reveals stratigraphic variations that are consistent with the long-term late Paleocene-Eocene pattern known from deep-sea carbonates. Through a consideration of the larger benthic foraminiferal record, and other micropalaeontological datums, it will be argued that the carbon-isotope stratigraphy captures the negative carbon isotope excursion associated with the PETM thereby allowing discussion of the effects of this event on shallow-water guyot environments. Although core recovery is extremely poor, it will be suggested that Site 871 provides an opportunity to examine the response of the shallow ocean carbonate factory to changes in carbon-cycle dynamics during the Early Cenozoic and assess any associated shallow water biotic and environmental changes. Identifying

  18. Ecological values of shallow-water habitats: Implications for the restoration of disturbed ecosystems

    USGS Publications Warehouse

    Lopez, C.B.; Cloern, J.E.; Schraga, T.S.; Little, A.J.; Lucas, L.V.; Thompson, J.K.; Burau, J.R.

    2006-01-01

    A presumed value of shallow-habitat enhanced pelagic productivity derives from the principle that in nutrient-rich aquatic systems phytoplankton growth rate is controlled by light availability, which varies inversely with habitat depth. We measured a set of biological indicators across the gradient of habitat depth within the Sacramento-San Joaquin River Delta (California) to test the hypothesis that plankton biomass, production, and pelagic energy flow also vary systematically with habitat depth. Results showed that phytoplankton biomass and production were only weakly related to phytoplankton growth rates whereas other processes (transport, consumption) were important controls. Distribution of the invasive clam Corbicula fluminea was patchy, and heavily colonized habitats all supported low phytoplankton biomass and production and functioned as food sinks. Surplus primary production in shallow, uncolonized habitats provided potential subsidies to neighboring recipient habitats. Zooplankton in deeper habitats, where grazing exceeded phytoplankton production, were likely supported by significant fluxes of phytoplankton biomass from connected donor habitats. Our results provide three important lessons for ecosystem science: (a) in the absence of process measurements, derived indices provide valuable information to improve our mechanistic understanding of ecosystem function and to benefit adaptive management strategies; (b) the benefits of some ecosystem functions are displaced by water movements, so the value of individual habitat types can only be revealed through a regional perspective that includes connectedness among habitats; and (c) invasive species can act as overriding controls of habitat function, adding to the uncertainty of management outcomes. ?? 2006 Springer Science+Business Media, Inc.

  19. Eastern Alaska

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In this SeaWiFS image of eastern Alaska, the Aleutian Islands, Kodiak Island, Yukon and Tanana rivers are clearly visible. Also visible, but slightly hidden beneath the clouds, is a bloom in Bristol Bay. Credit: Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  20. Methane Seep in Shallow-Water Permeable Sediment Harbors High Diversity of Anaerobic Methanotrophic Communities, Elba, Italy.

    PubMed

    Ruff, S Emil; Kuhfuss, Hanna; Wegener, Gunter; Lott, Christian; Ramette, Alban; Wiedling, Johanna; Knittel, Katrin; Weber, Miriam

    2016-01-01

    The anaerobic oxidation of methane (AOM) is a key biogeochemical process regulating methane emission from marine sediments into the hydrosphere. AOM is largely mediated by consortia of anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB), and has mainly been investigated in deep-sea sediments. Here we studied methane seepage at four spots located at 12 m water depth in coastal, organic carbon depleted permeable sands off the Island of Elba (Italy). We combined biogeochemical measurements, sequencing-based community analyses and in situ hybridization to investigate the microbial communities of this environment. Increased alkalinity, formation of free sulfide and nearly stoichiometric methane oxidation and sulfate reduction rates up to 200 nmol g(-1) day(-1) indicated the predominance of sulfate-coupled AOM. With up to 40 cm thickness the zones of AOM activity were unusually large and occurred in deeper sediment horizons (20-50 cm below seafloor) as compared to diffusion-dominated deep-sea seeps, which is likely caused by advective flow of pore water due to the shallow water depth and permeability of the sands. Hydrodynamic forces also may be responsible for the substantial phylogenetic and unprecedented morphological diversity of AOM consortia inhabiting these sands, including the clades ANME-1a/b, ANME-2a/b/c, ANME-3, and their partner bacteria SEEP-SRB1a and SEEP-SRB2. High microbial dispersal, the availability of diverse energy sources and high habitat heterogeneity might explain that the emission spots shared few microbial taxa, despite their physical proximity. Although the biogeochemistry of this shallow methane seep was very different to that of deep-sea seeps, their key functional taxa were very closely related, which supports the global dispersal of key taxa and underlines strong selection by methane as the predominant energy source. Mesophilic, methane-fueled ecosystems in shallow-water permeable sediments may comprise distinct

  1. Methane Seep in Shallow-Water Permeable Sediment Harbors High Diversity of Anaerobic Methanotrophic Communities, Elba, Italy

    PubMed Central

    Ruff, S. Emil; Kuhfuss, Hanna; Wegener, Gunter; Lott, Christian; Ramette, Alban; Wiedling, Johanna; Knittel, Katrin; Weber, Miriam

    2016-01-01

    The anaerobic oxidation of methane (AOM) is a key biogeochemical process regulating methane emission from marine sediments into the hydrosphere. AOM is largely mediated by consortia of anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB), and has mainly been investigated in deep-sea sediments. Here we studied methane seepage at four spots located at 12 m water depth in coastal, organic carbon depleted permeable sands off the Island of Elba (Italy). We combined biogeochemical measurements, sequencing-based community analyses and in situ hybridization to investigate the microbial communities of this environment. Increased alkalinity, formation of free sulfide and nearly stoichiometric methane oxidation and sulfate reduction rates up to 200 nmol g-1 day-1 indicated the predominance of sulfate-coupled AOM. With up to 40 cm thickness the zones of AOM activity were unusually large and occurred in deeper sediment horizons (20–50 cm below seafloor) as compared to diffusion-dominated deep-sea seeps, which is likely caused by advective flow of pore water due to the shallow water depth and permeability of the sands. Hydrodynamic forces also may be responsible for the substantial phylogenetic and unprecedented morphological diversity of AOM consortia inhabiting these sands, including the clades ANME-1a/b, ANME-2a/b/c, ANME-3, and their partner bacteria SEEP-SRB1a and SEEP-SRB2. High microbial dispersal, the availability of diverse energy sources and high habitat heterogeneity might explain that the emission spots shared few microbial taxa, despite their physical proximity. Although the biogeochemistry of this shallow methane seep was very different to that of deep-sea seeps, their key functional taxa were very closely related, which supports the global dispersal of key taxa and underlines strong selection by methane as the predominant energy source. Mesophilic, methane-fueled ecosystems in shallow-water permeable sediments may comprise distinct

  2. Links between the structure of an Antarctic shallow-water community and ice-scour frequency.

    PubMed

    Brown, Kirsty M; Fraser, Keiron P P; Barnes, David K A; Peck, Lloyd S

    2004-09-01

    Ice is a major structuring force in marine and freshwater environments at high latitudes. Although recovery from scouring has been quantified in time, the frequency of scouring in the Antarctic has not. We placed grids of markers at 9-17 m depth at two sites, to study ice-scouring over 2 years at Adelaide island (Antarctic Peninsula). We quantified the time scale of scour frequencies, and linked this to community mortality, age and diversity. Markers were hit from zero to at least three times in 2 years. At the least disturbed site (South Cove) 24% of markers were destroyed per year, whereas in North Cove 60% of markers were destroyed. There were significant differences in scouring frequency between our two sites: a given area in North Cove was on average hit twice as often as one in South Cove. Compared with near shore environments elsewhere, faunas of both sites were characteristic of high disturbance regimes, exhibiting low percent cover, diversity, ages and a high proportion of pioneers. Aspects of the encrusting communities studied reflected the differences between site disturbance regimes. North Cove was scoured twice as often, and bryozoan communities there had half the number of species, two-thirds the space occupation and twice the mortality level of those in South Cove. Maximum age in North Cove bryozoans was also half that in South Cove. Although there are natural disturbance events that rival ice-scouring in either frequency or catastrophic power at lower latitudes, none do both nor across such a wide depth range. We suggest that ice scour effects on polar benthos are even more significant than the same magnitude of disturbance at lower latitudes as recovery rates of high latitude communities are very slow. Climate warming seems likely to increase iceloading of near shore polar waters, so that some of the world's most intensely disturbed faunas may soon suffer even more disturbance.

  3. Lithostratigraphic, conodont, and other faunal links between lower Paleozoic strata in northern and central Alaska and northeastern Russia

    USGS Publications Warehouse

    Dumoulin, Julie A.; Harris, Anita G.; Gagiev, Mussa; Bradley, Dwight C.; Repetski, John E.

    2002-01-01

    Lower Paleozoic platform carbonate strata in northern Alaska (parts of the Arctic Alaska, York, and Seward terranes; herein called the North Alaska carbonate platform) and central Alaska (Farewell terrane) share distinctive lithologic and faunal features, and may have formed on a single continental fragment situated between Siberia and Laurentia. Sedimentary successions in northern and central Alaska overlie Late Proterozoic metamorphosed basement; contain Late Proterozoic ooid-rich dolostones, Middle Cambrian outer shelf deposits, and Ordovician, Silurian, and Devonian shallow-water platform facies, and include fossils of both Siberian and Laurentian biotic provinces. The presence in the Alaskan terranes of Siberian forms not seen in wellstudied cratonal margin sequences of western Laurentia implies that the Alaskan rocks were not attached to Laurentia during the early Paleozoic.The Siberian cratonal succession includes Archean basement, Ordovician shallow-water siliciclastic rocks, and Upper Silurian–Devonian evaporites, none of which have counterparts in the Alaskan successions, and contains only a few of the Laurentian conodonts that occur in Alaska. Thus we conclude that the lower Paleozoic platform successions of northern and central Alaska were not part of the Siberian craton during their deposition, but may have formed on a crustal fragment rifted away from Siberia during the Late Proterozoic. The Alaskan strata have more similarities to coeval rocks in some peri-Siberian terranes of northeastern Russia (Kotelny, Chukotka, and Omulevka). Lithologic ties between northern Alaska, the Farewell terrane, and the peri-Siberian terranes diminish after the Middle Devonian, but Siberian afµnities in northern and central Alaskan biotas persist into the late Paleozoic.

  4. Total energy and potential enstrophy conserving schemes for the shallow water equations using Hamiltonian methods - Part 1: Derivation and properties

    NASA Astrophysics Data System (ADS)

    Eldred, Christopher; Randall, David

    2017-02-01

    The shallow water equations provide a useful analogue of the fully compressible Euler equations since they have similar characteristics: conservation laws, inertia-gravity and Rossby waves, and a (quasi-) balanced state. In order to obtain realistic simulation results, it is desirable that numerical models have discrete analogues of these properties. Two prototypical examples of such schemes are the 1981 Arakawa and Lamb (AL81) C-grid total energy and potential enstrophy conserving scheme, and the 2007 Salmon (S07) Z-grid total energy and potential enstrophy conserving scheme. Unfortunately, the AL81 scheme is restricted to logically square, orthogonal grids, and the S07 scheme is restricted to uniform square grids. The current work extends the AL81 scheme to arbitrary non-orthogonal polygonal grids and the S07 scheme to arbitrary orthogonal spherical polygonal grids in a manner that allows for both total energy and potential enstrophy conservation, by combining Hamiltonian methods (work done by Salmon, Gassmann, Dubos, and others) and discrete exterior calculus (Thuburn, Cotter, Dubos, Ringler, Skamarock, Klemp, and others). Detailed results of the schemes applied to standard test cases are deferred to part 2 of this series of papers.

  5. Analysis of humpback whale sounds in shallow waters of the Southeastern Arabian Sea: An indication of breeding habitat.

    PubMed

    Mahanty, Madan M; Latha, G; Thirunavukkarasu, A

    2015-06-01

    The primary objective of this work was to present the acoustical identification of humpback whales, detected by using an autonomous ambient noise measurement system, deployed in the shallow waters of the Southeastern Arabian Sea (SEAS) during the period January to May 2011. Seven types of sounds were detected. These were characteristically upsweeps and downsweeps along with harmonics. Sounds produced repeatedly in a specific pattern were referred to as phrases (PQRS and ABC). Repeated phrases in a particular pattern were referred to as themes, and from the spectrographic analysis, two themes (I and II) were identified. The variation in the acoustic characteristics such as fundamental frequency, range, duration of the sound unit, and the structure of the phrases and themes are discussed. Sound units were recorded from mid-January to mid-March, with a peak in February, when the mean SST is approx. 28 degree C, and no presence was recorded after mid-March. The temporal and thematic structures strongly determine the functions of the humpback whale song form. Given the use of song in the SEAS, this area is possibly used as an active breeding habitat by humpback whales during the winter season.

  6. Inertia–gravity wave radiation from the elliptical vortex in the f-plane shallow water system

    NASA Astrophysics Data System (ADS)

    Sugimoto, Norihiko

    2017-04-01

    Inertia–gravity wave (IGW) radiation from the elliptical vortex is investigated in the f-plane shallow water system. The far field of IGW is analytically derived for the case of an almost circular Kirchhoff vortex with a small aspect ratio. Cyclone–anticyclone asymmetry appears at finite values of the Rossby number (Ro) caused by the source originating in the Coriolis acceleration. While the intensity of IGWs from the cyclone monotonically decreases as f increases, that from the anticyclone increases as f increases for relatively smaller f and has a local maximum at intermediate f. A numerical experiment is conducted on a model using a spectral method in an unbounded domain. The numerical results agree quite well with the analytical ones for elliptical vortices with small aspect ratios, implying that the derived analytical forms are useful for the verification of the numerical model. For elliptical vortices with larger aspect ratios, however, significant deviation from the analytical estimates appears. The intensity of IGWs radiated in the numerical simulation is larger than that estimated analytically. The reason is that the source of IGWs is amplified during the time evolution because the shape of the vortex changes from ideal ellipse to elongated with filaments. Nevertheless, cyclone–anticyclone asymmetry similar to the analytical estimate appears in all the range of aspect ratios, suggesting that this asymmetry is a robust feature.

  7. WASI-2D: A software tool for regionally optimized analysis of imaging spectrometer data from deep and shallow waters

    NASA Astrophysics Data System (ADS)

    Gege, Peter

    2014-01-01

    An image processing software has been developed which allows quantitative analysis of multi- and hyperspectral data from oceanic, coastal and inland waters. It has been implemented into the Water Colour Simulator WASI, which is a tool for the simulation and analysis of optical properties and light field parameters of deep and shallow waters. The new module WASI-2D can import atmospherically corrected images from airborne sensors and satellite instruments in various data formats and units like remote sensing reflectance or radiance. It can be easily adapted by the user to different sensors and to optical properties of the studied area. Data analysis is done by inverse modelling using established analytical models. The bio-optical model of the water column accounts for gelbstoff (coloured dissolved organic matter, CDOM), detritus, and mixtures of up to 6 phytoplankton classes and 2 spectrally different types of suspended matter. The reflectance of the sea floor is treated as sum of up to 6 substrate types. An analytic model of downwelling irradiance allows wavelength dependent modelling of sun glint and sky glint at the water surface. The provided database covers the spectral range from 350 to 1000 nm in 1 nm intervals. It can be exchanged easily to represent the optical properties of water constituents, bottom types and the atmosphere of the studied area.

  8. Characteristics of sound propagation in shallow water over an elastic seabed with a thin cap-rock layer.

    PubMed

    Duncan, Alec J; Gavrilov, Alexander N; McCauley, Robert D; Parnum, Iain M; Collis, Jon M

    2013-07-01

    Measurements of low-frequency sound propagation over the areas of the Australian continental shelf, where the bottom sediments consist primarily of calcarenite, have revealed that acoustic transmission losses are generally much higher than those observed over other continental shelves and remain relatively low only in a few narrow frequency bands. This paper considers this phenomenon and provides a physical interpretation in terms of normal modes in shallow water over a layered elastic seabed with a shear wave speed comparable to but lower than the water-column sound speed. A theoretical analysis and numerical modeling show that, in such environments, low attenuation of underwater sound is expected only in narrow frequency bands just above the modal critical frequencies which in turn are governed primarily by the water depth and compressional wave speed in the seabed. In addition, the effect of a thin layer of harder cap-rock overlaying less consolidated sediments is considered. Low-frequency transmission loss data collected from an offshore seismic survey in Bass Strait on the southern Australian continental shelf are analyzed and shown to be in broad agreement with the numerical predictions based on the theoretical analysis and modeling using an elastic parabolic equation solution for range-dependent bathymetry.

  9. A marching in space and time (MAST) solver of the shallow water equations. Part II: The 2D model

    NASA Astrophysics Data System (ADS)

    Aricò, C.; Nasello, C.; Tucciarelli, T.

    2007-05-01

    A novel methodology for the solution of the 2D shallow water equations is proposed. The algorithm is based on a fractional step decomposition of the original system in (1) a convective prediction, (2) a convective correction, and (3) a diffusive correction step. The convective components are solved using a Marching in Space and Time (MAST) procedure, that solves a sequence of small ODEs systems, one for each computational cell, ordered according to the cell value of a scalar approximated potential. The scalar potential is sought after computing first the minimum of a functional via the solution of a large linear system and then refining locally the optimum search. Model results are compared with the experimental data of two laboratory tests and with the results of other simulations carried out for the same tests by different authors. A comparison with the analytical solution of the oblique jump test has been also considered. Numerical results of the proposed scheme are in good agreement with measured data, as well as with analytical and higher order approximation methods results. The growth of the CPU time versus the cell number is investigated successively refining the elements of an initially coarse mesh. The CPU specific time, per element and per time step, is found out to be almost constant and no evidence of Courant-Friedrichs-Levi (CFL) number limitation has been detected in all the numerical experiments.

  10. Using a coherent hydrophone array for observing sperm whale range, classification, and shallow-water dive profiles.

    PubMed

    Tran, Duong D; Huang, Wei; Bohn, Alexander C; Wang, Delin; Gong, Zheng; Makris, Nicholas C; Ratilal, Purnima

    2014-06-01

    Sperm whales in the New England continental shelf and slope were passively localized, in both range and bearing, and classified using a single low-frequency (<2500 Hz), densely sampled, towed horizontal coherent hydrophone array system. Whale bearings were estimated using time-domain beamforming that provided high coherent array gain in sperm whale click signal-to-noise ratio. Whale ranges from the receiver array center were estimated using the moving array triangulation technique from a sequence of whale bearing measurements. Multiple concurrently vocalizing sperm whales, in the far-field of the horizontal receiver array, were distinguished and classified based on their horizontal spatial locations and the inter-pulse intervals of their vocalized click signals. The dive profile was estimated for a sperm whale in the shallow waters of the Gulf of Maine with 160 m water-column depth located close to the array's near-field where depth estimation was feasible by employing time difference of arrival of the direct and multiply reflected click signals received on the horizontal array. By accounting for transmission loss modeled using an ocean waveguide-acoustic propagation model, the sperm whale detection range was found to exceed 60 km in low to moderate sea state conditions after coherent array processing.

  11. Identifying sensitive areas of adaptive observations for prediction of the Kuroshio large meander using a shallow-water model

    NASA Astrophysics Data System (ADS)

    Zou, Guang'an; Wang, Qiang; Mu, Mu

    2016-09-01

    Sensitive areas for prediction of the Kuroshio large meander using a 1.5-layer, shallow-water ocean model were investigated using the conditional nonlinear optimal perturbation (CNOP) and first singular vector (FSV) methods. A series of sensitivity experiments were designed to test the sensitivity of sensitive areas within the numerical model. The following results were obtained: (1) the eff ect of initial CNOP and FSV patterns in their sensitive areas is greater than that of the same patterns in randomly selected areas, with the eff ect of the initial CNOP patterns in CNOP sensitive areas being the greatest; (2) both CNOP- and FSV-type initial errors grow more quickly than random errors; (3) the eff ect of random errors superimposed on the sensitive areas is greater than that of random errors introduced into randomly selected areas, and initial errors in the CNOP sensitive areas have greater eff ects on final forecasts. These results reveal that the sensitive areas determined using the CNOP are more sensitive than those of FSV and other randomly selected areas. In addition, ideal hindcasting experiments were conducted to examine the validity of the sensitive areas. The results indicate that reduction (or elimination) of CNOP-type errors in CNOP sensitive areas at the initial time has a greater forecast benefit than the reduction (or elimination) of FSV-type errors in FSV sensitive areas. These results suggest that the CNOP method is suitable for determining sensitive areas in the prediction of the Kuroshio large-meander path.

  12. Travel-time sensitivity kernels versus diffraction patterns obtained through double beam-forming in shallow water.

    PubMed

    Iturbe, Ion; Roux, Philippe; Virieux, Jean; Nicolas, Barbara

    2009-08-01

    In recent years, the use of sensitivity kernels for tomographic purposes has been frequently discussed in the literature. Sensitivity kernels of different observables (e.g., amplitude, travel-time, and polarization for seismic waves) have been proposed, and relationships between adjoint formulation, time-reversal theory, and sensitivity kernels have been developed. In the present study, travel-time sensitivity kernels (TSKs) are derived for two source-receiver arrays in an acoustic waveguide. More precisely, the TSKs are combined with a double time-delay beam-forming algorithm performed on two source-receiver arrays to isolate and identify each eigenray of the multipath propagation between a source-receiver pair in the acoustic waveguide. A relationship is then obtained between TSKs and diffraction theory. It appears that the spatial shapes of TSKs are equivalent to the gradients of the combined direction patterns of the source and receiver arrays. In the finite-frequency regimes, the combination of TSKs and double beam-forming both simplifies the calculation of TSK and increases the domain of validity for ray theory in shallow-water ocean acoustic tomography.

  13. Sensitivity analysis of 2D steady-state shallow water flow. Application to free surface flow model calibration

    NASA Astrophysics Data System (ADS)

    Guinot, Vincent; Cappelaere, Bernard

    2009-04-01

    This paper presents the analytical properties of the solutions of the sensitivity equations for steady-state, two-dimensional shallow water flow. These analytical properties are used to provide guidelines for model calibration and validation. The sensitivity of the water depth/level and that of the longitudinal unit discharge are shown to contain redundant information. Under subcritical conditions, the sensitivities of the flow variables are shown to obey an anisotropic elliptic equation. The main directions of the contour lines for water depth and the longitudinal unit discharge sensitivity are parallel and perpendicular to the flow, while they are diagonal to the flow for the transverse unit discharge sensitivity. Moreover, the sensitivity for all three variables extends farther in the transverse direction than in the longitudinal direction, the anisotropy ratio being a function of the sole Froude number. For supercritical flow, the sensitivity obeys an anisotropic hyperbolic equation. These findings are confirmed by application examples on idealized and real-world simulations. The sensitivities to the geometry, friction coefficient or model boundary conditions are shown to behave in different ways, thus providing different types of information for model calibration and validation.

  14. Firedrake-Fluids v0.1: numerical modelling of shallow water flows using an automated solution framework

    NASA Astrophysics Data System (ADS)

    Jacobs, C. T.; Piggott, M. D.

    2015-03-01

    This model description paper introduces a new finite element model for the simulation of non-linear shallow water flows, called Firedrake-Fluids. Unlike traditional models that are written by hand in static, low-level programming languages such as Fortran or C, Firedrake-Fluids uses the Firedrake framework to automatically generate the model's code from a high-level abstract language called Unified Form Language (UFL). By coupling to the PyOP2 parallel unstructured mesh framework, Firedrake can then target the code towards a desired hardware architecture to enable the efficient parallel execution of the model over an arbitrary computational mesh. The description of the model includes the governing equations, the methods employed to discretise and solve the governing equations, and an outline of the automated solution process. The verification and validation of the model, performed using a set of well-defined test cases, is also presented along with a road map for future developments and the solution of more complex fluid dynamical systems.

  15. Conventional versus pre-balanced forms of the shallow-water equations solved using finite-volume method

    NASA Astrophysics Data System (ADS)

    Lu, Xinhua; Xie, Shengbai

    2016-05-01

    In the existing literature, various forms of governing equations have been proposed to solve the shallow-water equations (SWEs). Recently, attention has been dedicated to the so-called "pre-balanced" form, because finite-volume schemes that are designed on this basis satisfy the well-balanced property. In this study, we theoretically investigate the relationship between numerical schemes devised using approximate Riemann solvers in the framework of finite-volume methods for solving the conventional form of the SWEs and its "pre-balanced" variant. We find that the numerical schemes for solving these two forms of the SWEs turn out to be identical when some widely employed upwind or centered approximate Riemann solvers are adopted for the numerical flux evaluations, such as the HLL (Harten, Lax, and van Leer), HLLC (HLL solver with restoring the contact surface), FORCE (first-order centered), and SLIC (slope limited centered) schemes. Some numerical experiments are performed, which verify the validity of the result of our theoretical analysis. The theoretical and numerical results suggest that the "pre-balanced" SWEs variant is not superior to the conventional one for solving the SWEs using approximate Riemann solvers.

  16. The shallow water equations as a hybrid flow model for the numerical and experimental analysis of hydro power stations

    SciTech Connect

    Ostermann, Lars; Seidel, Christian

    2015-03-10

    The numerical analysis of hydro power stations is an important method of the hydraulic design and is used for the development and optimisation of hydro power stations in addition to the experiments with the physical submodel of a full model in the hydraulic laboratory. For the numerical analysis, 2D and 3D models are appropriate and commonly used.The 2D models refer mainly to the shallow water equations (SWE), since for this flow model a large experience on a wide field of applications for the flow analysis of numerous problems in hydraulic engineering already exists. Often, the flow model is verified by in situ measurements. In order to consider 3D flow phenomena close to singularities like weirs, hydro power stations etc. the development of a hybrid fluid model is advantageous to improve the quality and significance of the global model. Here, an extended hybrid flow model based on the principle of the SWE is presented. The hybrid flow model directly links the numerical model with the experimental data, which may originate from physical full models, physical submodels and in-situ measurements. Hence a wide field of application of the hybrid model emerges including the improvement of numerical models and the strong coupling of numerical and experimental analysis.

  17. Multiscale/fractional step schemes for the numerical simulation of the rotating shallow water flows with complex periodic topography

    NASA Astrophysics Data System (ADS)

    Jauberteau, F.; Temam, R. M.; Tribbia, J.

    2014-08-01

    In this paper, we study several multiscale/fractional step schemes for the numerical solution of the rotating shallow water equations with complex topography. We consider the case of periodic boundary conditions (f-plane model). Spatial discretization is obtained using a Fourier spectral Galerkin method. For the schemes presented in this paper we consider two approaches. The first approach (multiscale schemes) is based on topography scale separation and the numerical time integration is function of the scales. The second approach is based on a splitting of the operators, and the time integration method is function of the operator considered (fractional step schemes). The numerical results obtained are compared with the explicit reference scheme (Leap-Frog scheme). With these multiscale/fractional step schemes the objective is to propose new schemes giving numerical results similar to those obtained using only one uniform fine grid N×N and a time step Δt, but with a CPU time near the CPU time needed when using only one coarse grid N1×N1, N1Δt.

  18. Role of parasequence-scale sequence stratigraphic analysis in integrated reservoir characterization and modeling of shallow-water carbonate strata

    SciTech Connect

    Kerans, C.; Lucia, F.J.; Bebout, D.G.; Major, R.P.; Ruppel, S.C. )

    1991-03-01

    The predictable stacking patterns of parasequences within different systems tracts of a sequence and of facies and rock-fabric successions within parasequences provide a powerful conceptual framework for integrated analysis of carbonate reservoirs. Stratigraphic analysis using a parasequence approach emphasizes correlation through comparative mapping of genetically related facies successions rather than the classic marker bed approach. The basic shallow-water carbonate parasequence is the upward-shallowing cycle ({approximately}fifth-order cycle, average period {minus}20,000 yr) that records a single progradational event represented most often by an upward-coarsening facies/rock-fabric succession. Interpretation of depositional environment is best accomplished at the parasequence scale because lateral facies relationships within these units best approximate time-equivalent genetically related deposits. The upward-shallowing facies succession that forms a parasequence provides a natural framework for quantification of geologic descriptions through rock-fabric-oriented petrophysical analysis. Permeability and saturation are directly related to sediment grain size, sorting, and interparticle porosity. Grain-dominated rocks have higher permeability and oil-saturation values than do mud-dominated rocks with the same interparticle porosity. Grain size and sorting occur systematically and predictably in the upward-shallowing parasequences. Porosity, grain size, and sorting can be significantly altered by diagenetic processes such as dolomitization, cementation, and dissolution. Diagenetic overprints are, however, commonly controlled by the depositional textures and thus also are predictable.

  19. Assimilation of TOPEX Sea Level Measurements with a Reduced-Gravity, Shallow Water Model of the Tropical Pacific Ocean

    NASA Technical Reports Server (NTRS)

    Fukumori, Ichiro

    1995-01-01

    Sea surface height variability measured by TOPEX is analyzed in the tropical Pacific Ocean by way of assimilation into a wind-driven, reduced-gravity, shallow water model using an approximate Kalman filter and smoother. The analysis results in an optimal fit of the dynamic model to the observations, providing it dynamically consistent interpolation of sea level and estimation of the circulation. Nearly 80% of the expected signal variance is accounted for by the model within 20 deg of the equator, and estimation uncertainty is substantially reduced by the voluminous observation. Notable features resolved by the analysis include seasonal changes associated with the North Equatorial Countercurrent and equatorial Kelvin and Rossby waves. Significant discrepancies are also found between the estimate and TOPEX measurements, especially near the eastern boundary. Improvements in the estimate made by the assimilation are validated by comparisons with independent tide gauge and current meter observations. The employed filter and smoother are based on approximately computed estimation error covariance matrices, utilizing a spatial transformation and an symptotic approximation. The analysis demonstrates the practical utility of a quasi-optimal filter and smoother.

  20. Velocity and sediment surge: What do we see at times of very shallow water on intertidal mudflats?

    NASA Astrophysics Data System (ADS)

    Zhang, Qian; Gong, Zheng; Zhang, Changkuan; Townend, Ian; Jin, Chuang; Li, Huan

    2016-02-01

    A self-designed "bottom boundary layer hydrodynamic and suspended sediment concentration (SSC) measuring system" was built to observe the hydrodynamic and the SSC processes over the intertidal mudflats at the middle part of the Jiangsu coast during August 8-10, 2013. Velocity profiles within 10 cm of the mudflat surface were obtained with a vertical resolution as fine as 1 mm. An ADCP was used to extend the profile over the full water depth with a resolution of 10 cm and the vertical SSC profile was measured at intervals using Optical Backscatter Sensors (OBS). At the same time, water levels and wave conditions were measured with a Tide and Wave Recorder. Measured data suggested that the vertical structure of velocity profiles within 10 cm above the bed maintains a logarithmic distribution during the whole tidal cycle except the slack-water periods. Shallow flows during both the early-flood period and the later-ebb period are characterized by a relatively large vertical velocity gradient and a "surge" feature. We conclude that the very shallow water stages are transient and may not contribute much to the whole water and sediment transport, while they can play a significant role in the formation and evolution of micro-topographies on tidal flats.