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Sample records for subtropical north pacific

  1. Impacts of ENSO diversity on the western Pacific and North Pacific subtropical highs during boreal summer

    NASA Astrophysics Data System (ADS)

    Paek, Houk; Yu, Jin-Yi; Zheng, Fei; Lu, Mong-Ming

    2016-07-01

    This study examines the interannual variability of the North Pacific high during boreal summer of 1979-2008 to understand how its leading modes are related to the two types of El Niño-Southern Oscillation (ENSO). In the observations, the first empirical orthogonal function mode (EOF1) is characterized by an in-phase variation between the western Pacific subtropical high (WPSH) and the northeastern Pacific subtropical high (NPSH), while the second mode (EOF2) is characterized by an out-of-phase WPSH-NPSH variation. The EOF1 mode dominates during the post early-1990s period and is a forced response to sea surface temperature (SST) variations over the maritime continent and tropical central Pacific (CP) regions related to developing CP ENSOs. Its in-phase WPSH-NPSH relationship is established through the ENSO-induced meridional atmospheric circulation, Pacific-North American pattern and eddy-zonal flow interaction over the North Pacific. In contrast, the EOF2 mode dominates prior to the early-1990s and is partially a forced response to tropical Indian Ocean (IO) and eastern Pacific (EP) SST variations related to decaying EP ENSOs and partially a coupled atmosphere-ocean response to western North Pacific SST variations. Of the 28 Atmospheric Model Intercomparison Project models, most (71 %) realistically simulate the EOF1 mode but only a few (14 %) simulate the EOF2 mode. The roughly 50 % underestimation in the strength of the EOF2 mode is due to model deficiencies in properly representing the atmospheric circulation responses to the IO and EP SST variations. This deficiency may be related to underestimations of the strength of the mean Walker circulation in the models.

  2. The annual silica cycle of the North Pacific subtropical gyre

    NASA Astrophysics Data System (ADS)

    Brzezinski, Mark A.; Krause, Jeffrey W.; Church, Matthew J.; Karl, David M.; Li, Binglin; Jones, Janice L.; Updyke, Brett

    2011-10-01

    Silica cycling in the upper 175 m of the North Pacific Subtropical Gyre was examined over a two year period (January 2008-December 2009) at the Hawaii Ocean Time-series (HOT) station ALOHA. Silicic acid concentrations in surface waters ranged from 0.6 to 1.6 μM, exhibiting no clear seasonal trends. Biogenic silica concentrations and silica production rates increased by an order of magnitude each summer following stratification of the upper 50 m reaching values of 157 nmol Si L -1 and 81 nmol Si L -1 d -1, in 2008 and 2009, respectively. Sea surface height anomalies together with analyses of variability in isothermal surfaces at 150-175 m indicated that the summer periods of elevated biogenic silica were associated with anticyclonic mesoscale features during both years. Lithogenic silica concentrations increased in the spring during the known period of maximum atmospheric dust concentrations with maximum values of 36 nmol Si L -1 in the upper 10 m. Dust deposition would enhance levels of dissolved iron in surface waters, but there was no response of diatom biomass or silica production to increases in near-surface ocean lithogenic silica concentrations suggesting iron sufficiency of diatom silica production rates. Low ambient silicic acid concentrations restricted silica production rates to an average of 43% of maximum potential rates. Si sufficiency only occurred during the summer period when diatom biomass was elevated suggesting that bloom diatoms are adapted to exploit low silicic acid concentrations. Annual silica production at HOT is estimated to be 63 mmol Si m -2 a -1 with summer blooms contributing 29% of the annual total. Diatoms are estimated to account for 3-7% of total phytoplankton primary productivity, but 9-20% of organic carbon export confirming past suggestions that diatoms are relatively minor contributors to primary productivity and autotrophic biomass, but important contributors to new and export production in oligotrophic open-ocean ecosystems

  3. Variability of chromophytic phytoplankton in the North Pacific Subtropical Gyre

    NASA Astrophysics Data System (ADS)

    Li, Binglin; Karl, David M.; Letelier, Ricardo M.; Bidigare, Robert R.; Church, Matthew J.

    2013-09-01

    Eukaryotic phytoplankton play important roles in regulating productivity and material export in oligotrophic ocean ecosystems. In this study, we examined the vertical and temporal variability in planktonic Chromalveolate (hereafter chromophyte) assemblages over a 2-year period (2007-2009) at Station ALOHA (22°45'N, 158°W) in the North Pacific Subtropical Gyre (NPSG). Polymerase chain reaction (PCR) amplification, cloning, and sequencing of form ID rbcL genes from samples collected at nearly monthly intervals provided information on the diversity, abundances, and variability associated with chromophytic phytoplankton. Despite persistently oligotrophic conditions, the euphotic zone of this habitat supported a phylogenetically diverse assemblage of chromophytic algae, including representatives of various genera of diatoms, pelagophytes, prymnesiophytes, and dinoflagellates. Quantitative PCR (qPCR) amplification of diatom, prymnesiophyte, and pelagophyte rbcL phylotypes revealed that the population structure of these assemblages was highly variable in time, with gene abundances often varying more than an order of magnitude between successive months. Diatom rbcL genes were typically the most abundant in both the upper and lower regions of the euphotic zone, while rbcL gene abundances of the prymnesiophytes and pelagophytes were significantly greater (One-way ANOVA, P<0.05) in the lower regions of the euphotic zone (75-125 m) than in the upper euphotic zone (5-45 m). Similarly, we observed elevated concentrations of 19-hexanoxyfucoxanthin and 19-butanoxyfucoxanin (diagnostic pigments of prymnesiophytes and pelagophytes, respectively) in the lower euphotic zone, while concentrations of fucoxanthin (a diagnostic diatom pigment) demonstrated less vertical structure. Analyses of samples collected using sediment traps deployed at 150 m revealed that members of diatoms, prymnesiophytes, and pelagophytes all contributed to material export out of the upper ocean. None of the

  4. Concurrent Decadal Mesoscale Eddy Modulations in the Western North Pacific Subtropical Gyre

    NASA Astrophysics Data System (ADS)

    Qiu, B.; Chen, S.

    2012-12-01

    Satellite altimeter data of the past two decades are used to investigate the low-frequency mesoscale eddy variability inside the western North Pacific subtropical gyre. Eddy activity modulations with a decadal timescale are detected concurrently within the 18-28N band, including the three branches of the Subtropical Countercurrent (STCC) and the Hawaiian Lee Countercurrent (HLCC). In close connection with the Pacific decadal oscillation (PDO) index, enhanced eddy activities were detected in 1995-98 and 2003-06, whereas the eddy activities were below the average in 1999-2001 and 2009-11. Analysis of the temperature and salinity data that became available after 2001 via the International Argo Program reveals that the modulating eddy activities are due to the decadal change in the upper ocean eastward shear in the broad-scale STCC/HLCC band. By conducting an upper ocean temperature budget analysis, we found that this observed eastward shear change can be effectively accounted for by the decadally-varying surface heat flux forcing. Using the Argo-based temperature and salinity data, it is further found that the decadal subsurface potential vorticity (PV) signals to the north and beneath the STCC/HLCC were vertically coherent and not confined to the mode water isopycnals. Adjusting to the PDO-related surface forcing, these subsurface PV anomalies lagged behind the upper ocean eastward shear signals and likely made minor contributions to generate the decadally-varying eddy signals observed in the western North Pacific subtropical gyre.

  5. Intermediate water circulation in the North Pacific subarctic and northern subtropical regions

    NASA Astrophysics Data System (ADS)

    Ueno, Hiromichi; Yasuda, Ichiro

    2003-11-01

    The intermediate water circulation in the North Pacific subarctic and northern subtropical regions is investigated through inverse analysis, focusing on the volume and heat transports from the subtropical to the subarctic regions. The inverse method we adopted is a hybrid method of β-spiral and box inverse methods which permits diapycnal flux. The isopycnal velocities estimated through the inverse analysis are mostly consistent with the oxygen distribution and support the hypothesis that warm and saline intermediate water is transported from the transition domain east of Japan to the northern Gulf of Alaska. The northward volume transport across 46°N between 158°E and 130°W is estimated to be -0.2 to 5.3 Sv in the density range of 26.7-27.2σθ. The upward diapycnal transports in the open subarctic North Pacific (region N) across 26.7 and 27.2σθ isopycnal surfaces are estimated to be 0.2 to 1.5 Sv and -0.2 to 0.9 Sv, respectively. Part of the water transported upward across 26.7σθ might outcrop and be carried to the subtropical region by the southward Ekman drift. Through the examination of heat balance of the intermediate layer in the subarctic region, it is suggested quantitatively that the intermediate heat transport from the south plays an essential role in maintaining the heat of the mesothermal waters in the subarctic region.

  6. Seasonal variability in the phytoplankton community of the North Pacific Subtropical Gyre

    SciTech Connect

    Winn, C.D.; Campbell, L.; Christian, J.R.

    1995-12-01

    This study was performed to assess seasonal cycles in fluorescence and chlorophyll concentrations in the North Pacific Subtropical Gyre. Flow cytometry and continuous in situ flash fluorescence were used to measureme in situ fluorescence, extracted chlorophyll a, primary productivity, extracted adenosine 5-triphosphate, and fluorescence per cell. Chlorophyll a concentrations increased in winter and decreased in summer in the upper euphotic zone. In the lower euphotic zone, however, chlorophyll a concentrations increased in spring and decreased in fall. The winter increase in the upper zone appeared to be caused by photoadaptation to decreased light intensity. The seasonal variation in the lower zone was indicative of a change in primary production rate and phytoplankton biomass due to increased light intensity. Based on the similarities of these observations to satellite data and other regional data, the seasonal patterns identified in this study may be common to large areas of subtropical oceans. 52 refs., 7 figs., 2 tabs.

  7. Enhancement of phytoplankton chlorophyll by submesoscale frontal dynamics in the North Pacific Subtropical Gyre

    NASA Astrophysics Data System (ADS)

    Liu, Xiao; Levine, Naomi M.

    2016-02-01

    Subtropical gyres contribute significantly to global ocean productivity. As the climate warms, the strength of these gyres as a biological carbon pump is predicted to diminish due to increased stratification and depleted surface nutrients. We present results suggesting that the impact of submesoscale physics on phytoplankton in the oligotrophic ocean is substantial and may either compensate or exacerbate future changes in carbon cycling. A new statistical tool was developed to quantify surface patchiness from sea surface temperatures. Chlorophyll concentrations in the North Pacific Subtropical Gyre were shown to be enhanced by submesoscale frontal dynamics with an average increase of 38% (maximum of 83%) during late winter. The magnitude of this enhancement is comparable to the observed decline in chlorophyll due to a warming of ~1.1°C. These results highlight the need for an improved understanding of fine-scale physical variability in order to predict the response of marine ecosystems to projected climate changes.

  8. Uncertainty in future projections of the North Pacific subtropical high and its implication for California winter precipitation change

    NASA Astrophysics Data System (ADS)

    Choi, Jung; Lu, Jian; Son, Seok-Woo; Frierson, Dargan M. W.; Yoon, Jin-Ho

    2016-01-01

    This study examines future projections of sea level pressure change in the North Pacific and its impact on winter precipitation changes in California. The multimodel analysis, based on the Coupled Model Intercomparison Project phase 5 models under the Representative Concentration Pathway 8.5 scenario, shows a robust sea level pressure change in the late 21st century over the western North Pacific in which both the Aleutian Low and the North Pacific subtropical high (NPSH) shift poleward in concert with a widening of the Hadley cell. This change is partly explained by a systematic increase of static stability in the subtropics. Despite its robustness, the projected NPSH changes over the eastern North Pacific exhibit a substantial intermodel spread, contributing as a cause for uncertain projections of precipitation changes in California. This intermodel spread in the eastern North Pacific is associated with a Pacific Decadal Oscillation-like surface temperature change in the western North Pacific and the resulting meridional temperature gradient change. This study points to a major source of uncertainty for the response of winter precipitation to global warming over the West Coast of North America: atmosphere-ocean coupling in the North Pacific.

  9. Enhanced or Weakened Western North Pacific Subtropical High under Global Warming?

    PubMed

    He, Chao; Zhou, Tianjun; Lin, Ailan; Wu, Bo; Gu, Dejun; Li, Chunhui; Zheng, Bin

    2015-01-01

    The Western North Pacific Subtropical High (WNPSH) regulates East Asian climate in summer. Anomalous WNPSH causes floods, droughts and heat waves in China, Japan and Korea. The potential change of the WNPSH under global warming is concerned by Asian people, but whether the WNPSH would be enhanced or weakened remains inconclusive. Based on the multi-model climate change projection from the 5th phase of Coupled Model Intercomparison Project (CMIP5), we show evidences that the WNPSH tends to weaken and retreat eastward in the mid-troposphere in response to global warming, accompanied by an eastward expansion of East Asian rain belt along the northwestern flank of WNPSH. Weakened meridional temperature gradient on the northern flank of WNPSH and the associated thermal wind account for the weakened WNPSH in the mid troposphere. We recommend the WNPSH be measured by eddy geopotential height (He) instead of traditionally used geopotential height, especially in climate change studies. PMID:26608354

  10. Enhanced or Weakened Western North Pacific Subtropical High under Global Warming?

    NASA Astrophysics Data System (ADS)

    He, Chao; Zhou, Tianjun; Lin, Ailan; Wu, Bo; Gu, Dejun; Li, Chunhui; Zheng, Bin

    2015-11-01

    The Western North Pacific Subtropical High (WNPSH) regulates East Asian climate in summer. Anomalous WNPSH causes floods, droughts and heat waves in China, Japan and Korea. The potential change of the WNPSH under global warming is concerned by Asian people, but whether the WNPSH would be enhanced or weakened remains inconclusive. Based on the multi-model climate change projection from the 5th phase of Coupled Model Intercomparison Project (CMIP5), we show evidences that the WNPSH tends to weaken and retreat eastward in the mid-troposphere in response to global warming, accompanied by an eastward expansion of East Asian rain belt along the northwestern flank of WNPSH. Weakened meridional temperature gradient on the northern flank of WNPSH and the associated thermal wind account for the weakened WNPSH in the mid troposphere. We recommend the WNPSH be measured by eddy geopotential height (He) instead of traditionally used geopotential height, especially in climate change studies.

  11. Multicore structure of the North Pacific subtropical mode water from enhanced Argo observations

    NASA Astrophysics Data System (ADS)

    Gao, Wendian; Li, Peiliang; Xie, Shang-Ping; Xu, Lixiao; Liu, Cong

    2016-02-01

    Seventeen Argo profiling floats with enhanced vertical and temporal sampling were deployed in the Kuroshio recirculation gyre in the western North Pacific in late March 2014. The Subtropical Mode Water (STMW) observed in many profiles displays a "multicore structure" with more than one minima in potential vorticity (PV), corroborated by vertical covariations in apparent oxygen utilization (AOU). These cores are classified into four submodes according to density and AOU. The submode waters are typically 100 m thick, in which PV varies by 1 × 10-10 m-1 s-1 and AOU by 10 µmole/kg. The STMW multicore structure is most frequently observed in spring, gradually taken over by single-core profiles into summer. The seasonal evolution is suggestive of vertical mixing, especially in STMW of lower density.

  12. Response of North Pacific eastern subtropical mode water to greenhouse gas versus aerosol forcing

    NASA Astrophysics Data System (ADS)

    Li, Xiang; Luo, Yiyong

    2016-04-01

    Mode water is a distinct water mass characterized by a near vertical homogeneous layer or low potential vorticity, and is considered essential for understanding ocean climate variability. Based on the output of GFDL CM3, this study investigates the response of eastern subtropical mode water (ESTMW) in the North Pacific to two different single forcings: greenhouse gases (GHGs) and aerosol. Under GHG forcing, ESTMW is produced on lighter isopycnal surfaces and is decreased in volume. Under aerosol forcing, in sharp contrast, it is produced on denser isopycnal surfaces and is increased in volume. The main reason for the opposite response is because surface ocean-to-atmosphere latent heat flux change over the ESTMW formation region shoals the mixed layer and thus weakens the lateral induction under GHG forcing, but deepens the mixed layer and thus strengthens the lateral induction under aerosol forcing. In addition, local wind changes are also favorable to the opposite response of ESTMW production to GHG versus aerosol.

  13. The Relationship between the Western North Pacific Subtropical High and the East Asian Surface Ozone

    NASA Astrophysics Data System (ADS)

    Wie, Jieun; Kim, Ga-Young; Moon, Byung-Kwon

    2016-04-01

    The tropospheric ozone is known as one of the short-lived climate pollutants and the greenhouse gases, but little is known about it. The purpose of this study is to diagnose the relationship between the western North Pacific subtropical high and the East Asian surface ozone. For the study, we used the trajectory enhanced tropospheric ozone residual (TTOR) for 9 years (2005-2013) and GEOS-Chem model data for 41 years (1971-2011). Despite the short period, the observation well shows the ozone concentration changes according to the WNPSH strength and the model as well. WNPSH enhances the convection along the East Asian monsoon band and the surface ozone concentration decreases. The ozone concentration increases in the area around the rainband. Depending on the location of the rain band, the ozone concentration changes. This study indicates that the ozone concentration is affected by not only the emission of ozone precursors and but also the meteorological condition.

  14. Enhanced or Weakened Western North Pacific Subtropical High under Global Warming?

    PubMed

    He, Chao; Zhou, Tianjun; Lin, Ailan; Wu, Bo; Gu, Dejun; Li, Chunhui; Zheng, Bin

    2015-11-26

    The Western North Pacific Subtropical High (WNPSH) regulates East Asian climate in summer. Anomalous WNPSH causes floods, droughts and heat waves in China, Japan and Korea. The potential change of the WNPSH under global warming is concerned by Asian people, but whether the WNPSH would be enhanced or weakened remains inconclusive. Based on the multi-model climate change projection from the 5th phase of Coupled Model Intercomparison Project (CMIP5), we show evidences that the WNPSH tends to weaken and retreat eastward in the mid-troposphere in response to global warming, accompanied by an eastward expansion of East Asian rain belt along the northwestern flank of WNPSH. Weakened meridional temperature gradient on the northern flank of WNPSH and the associated thermal wind account for the weakened WNPSH in the mid troposphere. We recommend the WNPSH be measured by eddy geopotential height (He) instead of traditionally used geopotential height, especially in climate change studies.

  15. Diatoms in the desert: Plankton community response to a mesoscale eddy in the subtropical North Pacific

    NASA Astrophysics Data System (ADS)

    Brown, Susan L.; Landry, Michael R.; Selph, Karen E.; Jin Yang, Eun; Rii, Yoshimi M.; Bidigare, R. R.

    2008-05-01

    As part of the E-Flux project, we documented spatial variability and temporal changes in plankton community structure in a cold-core cyclonic eddy in the lee of the Hawaiian Islands. Cyclone Opal spanned 200 km in diameter, with sharply uplifted isopycnals (80-100 m relative to surrounding waters) and a strongly expressed deep chlorophyll a maximum (DCM) in its central core region of 40 km diameter. Microscopic and flow cytometric analyses of samples from across the eddy revealed dramatic transitions in phytoplankton community structure, reflecting Opal's well-developed physical structure. Upper mixed-layer populations in the eddy resembled those outside the eddy and were dominated by picophytoplankton. In contrast, the DCM was composed of large chain-forming diatoms dominated by Chaetoceros and Rhizosolenia spp. Diatoms attained unprecedented levels of biomass (nearly 90 μg C l -1) in the center of the eddy, accounting for 85% of photosynthetic biomass. Protozoan grazers displayed two- to three-fold higher biomass levels in the eddy center as well. We also found a distinct and persistent layer of senescent diatom cells overlying healthy populations, often separated by less than 10 m, indicating that we were sampling a bloom in a state of decline. Time-series sampling over 8 days showed a successional shift in community structure within the central diatom bloom, from the unexpected large chain-forming species to smaller forms more typical of the subtropical North Pacific. The diatom bloom of Cyclone Opal was a unique, and possibly extreme, example of biological response to physical forcing in the North Pacific subtropical gyre, and its detailed study may therefore help to improve our predictive understanding of environmental controls on plankton community structure.

  16. Gooseneck barnacles (Lepas spp.) ingest microplastic debris in the North Pacific Subtropical Gyre.

    PubMed

    Goldstein, Miriam C; Goodwin, Deborah S

    2013-01-01

    Substantial quantities of small plastic particles, termed "microplastic," have been found in many areas of the world ocean, and have accumulated in particularly high densities on the surface of the subtropical gyres. While plastic debris has been documented on the surface of the North Pacific Subtropical Gyre (NPSG) since the early 1970s, the ecological implications remain poorly understood. Organisms associated with floating objects, termed the "rafting assemblage," are an important component of the NPSG ecosystem. These objects are often dominated by abundant and fast-growing gooseneck barnacles (Lepas spp.), which predate on plankton and larval fishes at the sea surface. To assess the potential effects of microplastic on the rafting community, we examined the gastrointestinal tracts of 385 barnacles collected from the NPSG for evidence of plastic ingestion. We found that 33.5% of the barnacles had plastic particles present in their gastrointestinal tract, ranging from one plastic particle to a maximum of 30 particles. Particle ingestion was positively correlated to capitulum length, and no blockage of the stomach or intestines was observed. The majority of ingested plastic was polyethylene, with polypropylene and polystyrene also present. Our results suggest that barnacle ingestion of microplastic is relatively common, with unknown trophic impacts on the rafting community and the NPSG ecosystem.

  17. Gooseneck barnacles (Lepas spp.) ingest microplastic debris in the North Pacific Subtropical Gyre.

    PubMed

    Goldstein, Miriam C; Goodwin, Deborah S

    2013-01-01

    Substantial quantities of small plastic particles, termed "microplastic," have been found in many areas of the world ocean, and have accumulated in particularly high densities on the surface of the subtropical gyres. While plastic debris has been documented on the surface of the North Pacific Subtropical Gyre (NPSG) since the early 1970s, the ecological implications remain poorly understood. Organisms associated with floating objects, termed the "rafting assemblage," are an important component of the NPSG ecosystem. These objects are often dominated by abundant and fast-growing gooseneck barnacles (Lepas spp.), which predate on plankton and larval fishes at the sea surface. To assess the potential effects of microplastic on the rafting community, we examined the gastrointestinal tracts of 385 barnacles collected from the NPSG for evidence of plastic ingestion. We found that 33.5% of the barnacles had plastic particles present in their gastrointestinal tract, ranging from one plastic particle to a maximum of 30 particles. Particle ingestion was positively correlated to capitulum length, and no blockage of the stomach or intestines was observed. The majority of ingested plastic was polyethylene, with polypropylene and polystyrene also present. Our results suggest that barnacle ingestion of microplastic is relatively common, with unknown trophic impacts on the rafting community and the NPSG ecosystem. PMID:24167779

  18. Gooseneck barnacles (Lepas spp.) ingest microplastic debris in the North Pacific Subtropical Gyre

    PubMed Central

    Goodwin, Deborah S.

    2013-01-01

    Substantial quantities of small plastic particles, termed “microplastic,” have been found in many areas of the world ocean, and have accumulated in particularly high densities on the surface of the subtropical gyres. While plastic debris has been documented on the surface of the North Pacific Subtropical Gyre (NPSG) since the early 1970s, the ecological implications remain poorly understood. Organisms associated with floating objects, termed the “rafting assemblage,” are an important component of the NPSG ecosystem. These objects are often dominated by abundant and fast-growing gooseneck barnacles (Lepas spp.), which predate on plankton and larval fishes at the sea surface. To assess the potential effects of microplastic on the rafting community, we examined the gastrointestinal tracts of 385 barnacles collected from the NPSG for evidence of plastic ingestion. We found that 33.5% of the barnacles had plastic particles present in their gastrointestinal tract, ranging from one plastic particle to a maximum of 30 particles. Particle ingestion was positively correlated to capitulum length, and no blockage of the stomach or intestines was observed. The majority of ingested plastic was polyethylene, with polypropylene and polystyrene also present. Our results suggest that barnacle ingestion of microplastic is relatively common, with unknown trophic impacts on the rafting community and the NPSG ecosystem. PMID:24167779

  19. Summer diatom blooms in the North Pacific subtropical gyre: 2008-2009.

    PubMed

    Villareal, Tracy A; Brown, Colbi G; Brzezinski, Mark A; Krause, Jeffrey W; Wilson, Cara

    2012-01-01

    The summertime North Pacific subtropical gyre has widespread phytoplankton blooms between Hawaii and the subtropical front (∼30°N) that appear as chlorophyll (chl) increases in satellite ocean color data. Nitrogen-fixing diatom symbioses (diatom-diazotroph associations: DDAs) often increase 10(2)-10(3) fold in these blooms and contribute to elevated export flux. In 2008 and 2009, two cruises targeted satellite chlorophyll blooms to examine DDA species abundance, chlorophyll concentration, biogenic silica concentration, and hydrography. Generalized observations that DDA blooms occur when the mixed layer depth is < 70 m are supported, but there is no consistent relationship between mixed layer depth, bloom intensity, or composition; regional blooms between 22-34°N occur within a broader temperature range (21-26°C) than previously reported. In both years, the Hemiaulus-Richelia and Rhizosolenia-Richelia DDAs increased 10(2)-10(3) over background concentrations within satellite-defined bloom features. The two years share a common trend of Hemiaulus dominance of the DDAs and substantial increases in the >10 µm chl a fraction (∼40-90+% of total chl a). Integrated diatom abundance varied 10-fold over <10 km. Biogenic silica concentration tracked diatom abundance, was dominated by the >10 µm size fraction, and increased up to 5-fold in the blooms. The two years differed in the magnitude of the surface chl a increase (2009>2008), the abundance of pennate diatoms within the bloom (2009>2008), and the substantially greater mixed layer depth in 2009. Only the 2009 bloom had sufficient chl a in the >10 µm fraction to produce the observed ocean color chl increase. Blooms had high spatial variability; ocean color images likely average over numerous small events over time and space scales that exceed the individual event scale. Summertime DDA export flux noted at the Hawaii time-series Sta. ALOHA is probably a generalized feature of the eastern N. Pacific north to the

  20. Scale interaction between typhoons and the North Pacific subtropical high and associated remote effects during the Baiu/Meiyu season

    NASA Astrophysics Data System (ADS)

    Hirata, Hidetaka; Kawamura, Ryuichi

    2014-05-01

    The interaction between typhoons and the North Pacific subtropical high and the associated remote impact on East Asian and North Pacific anomalous weather during the Baiu/Meiyu season have been investigated using the Japanese long-term Reanalysis project data aided by the Japan Meteorological Agency Climate Data Assimilation System. The typhoons that appeared in July have been categorized into two primary tracks, the Hainan Island course (HC) and the Okinawa Island course (OC). A typhoon gives rise to negative absolute vorticity advection along its eastern periphery, which locally reinforces the western ridge of the North Pacific subtropical high, whereas the resultant anomalous high stimulates the westward (northward) migration of the HC (OC) typhoon through its combination with the background flow. A combined effect of the typhoon and its induced anomalous anticyclonic circulation increases the transportation of moisture into the Baiu/Meiyu frontal zone in the vicinity of Japan. Over the East China Sea and the Sea of Japan, northward or northeastward moisture flux is pronounced along the western periphery of the typhoon-induced anticyclonic circulation anomaly in the HC category, triggering heavy rainfall on central Japan's Sea of Japan coast. Similar remote effects also operate in the OC category, which is responsible for the occurrence of extremely heavy rainfall along the Pacific coast of western Japan. When an OC typhoon approaches the Asian jet, it is capable of giving rise to anticyclonic vorticity within the jet, leading to the downstream development of stationary Rossby wave packets via the North Pacific waveguide.

  1. Non-random assembly of bacterioplankton communities in the subtropical north pacific ocean.

    PubMed

    Eiler, Alexander; Hayakawa, Darin H; Rappé, Michael S

    2011-01-01

    The exploration of bacterial diversity in the global ocean has revealed new taxa and previously unrecognized metabolic potential; however, our understanding of what regulates this diversity is limited. Using terminal restriction fragment length polymorphism (T-RFLP) data from bacterial small-subunit ribosomal RNA genes we show that, independent of depth and time, a large fraction of bacterioplankton co-occurrence patterns are non-random in the oligotrophic North Pacific subtropical gyre (NPSG). Pair-wise correlations of all identified operational taxonomic units (OTUs) revealed a high degree of significance, with 6.6% of the pair-wise co-occurrences being negatively correlated and 20.7% of them being positive. The most abundant OTUs, putatively identified as Prochlorococcus, SAR11, and SAR116 bacteria, were among the most correlated OTUs. As expected, bacterial community composition lacked statistically significant patterns of seasonality in the mostly stratified water column except in a few depth horizons of the sunlit surface waters, with higher frequency variations in community structure apparently related to populations associated with the deep chlorophyll maximum. Communities were structured vertically into epipelagic, mesopelagic, and bathypelagic populations. Permutation-based statistical analyses of T-RFLP data and their corresponding metadata revealed a broad range of putative environmental drivers controlling bacterioplankton community composition in the NPSG, including concentrations of inorganic nutrients and phytoplankton pigments. Together, our results suggest that deterministic forces such as environmental filtering and interactions among taxa determine bacterioplankton community patterns, and consequently affect ecosystem functions in the NPSG.

  2. Quantifying subtropical North Pacific gyre mixed layer primary productivity from Seaglider observations of diel oxygen cycles

    NASA Astrophysics Data System (ADS)

    Nicholson, David P.; Wilson, Samuel T.; Doney, Scott C.; Karl, David M.

    2015-05-01

    Using autonomous underwater gliders, we quantified diurnal periodicity in dissolved oxygen, chlorophyll, and temperature in the subtropical North Pacific near the Hawaii Ocean Time-series (HOT) Station ALOHA during summer 2012. Oxygen optodes provided sufficient stability and precision to quantify diel cycles of average amplitude of 0.6 µmol kg-1. A theoretical diel curve was fit to daily observations to infer an average mixed layer gross primary productivity (GPP) of 1.8 mmol O2 m-3 d-1. Cumulative net community production (NCP) over 110 days was 500 mmol O2 m-2 for the mixed layer, which averaged 57 m in depth. Both GPP and NCP estimates indicated a significant period of below-average productivity at Station ALOHA in 2012, an observation confirmed by 14C productivity incubations and O2/Ar ratios. Given our success in an oligotrophic gyre where biological signals are small, our diel GPP approach holds promise for remote characterization of productivity across the spectrum of marine environments.

  3. Non-Random Assembly of Bacterioplankton Communities in the Subtropical North Pacific Ocean

    PubMed Central

    Eiler, Alexander; Hayakawa, Darin H.; Rappé, Michael S.

    2011-01-01

    The exploration of bacterial diversity in the global ocean has revealed new taxa and previously unrecognized metabolic potential; however, our understanding of what regulates this diversity is limited. Using terminal restriction fragment length polymorphism (T-RFLP) data from bacterial small-subunit ribosomal RNA genes we show that, independent of depth and time, a large fraction of bacterioplankton co-occurrence patterns are non-random in the oligotrophic North Pacific subtropical gyre (NPSG). Pair-wise correlations of all identified operational taxonomic units (OTUs) revealed a high degree of significance, with 6.6% of the pair-wise co-occurrences being negatively correlated and 20.7% of them being positive. The most abundant OTUs, putatively identified as Prochlorococcus, SAR11, and SAR116 bacteria, were among the most correlated OTUs. As expected, bacterial community composition lacked statistically significant patterns of seasonality in the mostly stratified water column except in a few depth horizons of the sunlit surface waters, with higher frequency variations in community structure apparently related to populations associated with the deep chlorophyll maximum. Communities were structured vertically into epipelagic, mesopelagic, and bathypelagic populations. Permutation-based statistical analyses of T-RFLP data and their corresponding metadata revealed a broad range of putative environmental drivers controlling bacterioplankton community composition in the NPSG, including concentrations of inorganic nutrients and phytoplankton pigments. Together, our results suggest that deterministic forces such as environmental filtering and interactions among taxa determine bacterioplankton community patterns, and consequently affect ecosystem functions in the NPSG. PMID:21747815

  4. Wind and sunlight shape microbial diversity in surface waters of the North Pacific Subtropical Gyre

    PubMed Central

    Bryant, Jessica A; Aylward, Frank O; Eppley, John M; Karl, David M; Church, Matthew J; DeLong, Edward F

    2016-01-01

    Few microbial time-series studies have been conducted in open ocean habitats having low seasonal variability such as the North Pacific Subtropical Gyre (NPSG), where surface waters experience comparatively mild seasonal variation. To better describe microbial seasonal variability in this habitat, we analyzed rRNA amplicon and shotgun metagenomic data over two years at the Hawaii Ocean Time-series Station ALOHA. We postulated that this relatively stable habitat might reveal different environmental factors that influence planktonic microbial community diversity than those previously observed in more seasonally dynamic habitats. Unexpectedly, the data showed that microbial diversity at 25 m was positively correlated with average wind speed 3 to 10 days prior to sampling. In addition, microbial community composition at 25 m exhibited significant correlations with solar irradiance. Many bacterial groups whose relative abundances varied with solar radiation corresponded to taxa known to exhibit strong seasonality in other oceanic regions. Network co-correlation analysis of 25 m communities showed seasonal transitions in composition, and distinct successional cohorts of co-occurring phylogenetic groups. Similar network analyses of metagenomic data also indicated distinct seasonality in genes originating from cyanophage, and several bacterial clades including SAR116 and SAR324. At 500 m, microbial community diversity and composition did not vary significantly with any measured environmental parameters. The minimal seasonal variability in the NPSG facilitated detection of more subtle environmental influences, such as episodic wind variation, on surface water microbial diversity. Community composition in NPSG surface waters varied in response to solar irradiance, but less dramatically than reported in other ocean provinces. PMID:26645474

  5. Nitrate supply from deep to near-surface waters of the North Pacific subtropical gyre.

    PubMed

    Johnson, Kenneth S; Riser, Stephen C; Karl, David M

    2010-06-24

    Concentrations of dissolved inorganic carbon (DIC) decrease in the surface mixed layers during spring and summer in most of the oligotrophic ocean. Mass balance calculations require that the missing DIC is converted into particulate carbon by photosynthesis. This DIC uptake represents one of the largest components of net community production in the world ocean. However, mixed-layer waters in these regions of the ocean typically contain negligible concentrations of plant nutrients such as nitrate and phosphate. Combined nutrient supply mechanisms including nitrogen fixation, diffusive transport and vertical entrainment are believed to be insufficient to supply the required nutrients for photosynthesis. The basin-scale potential for episodic nutrient transport by eddy events is unresolved. As a result, it is not understood how biologically mediated DIC uptake can be supported in the absence of nutrients. Here we report on high-resolution measurements of nitrate (NO(3)(-)) and oxygen (O(2)) concentration made over 21 months using a profiling float deployed near the Hawaii Ocean Time-series station in the North Pacific subtropical gyre. Our measurements demonstrate that as O(2) was produced and DIC was consumed over two annual cycles, a corresponding seasonal deficit in dissolved NO(3)(-) appeared in water at depths from 100 to 250 m. The deep-water deficit in NO(3)(-) was in near-stoichiometric balance with the fixed nitrogen exported to depth. Thus, when the water column from the surface to 250 m is considered as a whole, there is near equivalence between nutrient supply and demand. Short-lived transport events (<10 days) that connect deep stocks of nitrate to nutrient-poor surface waters were clearly present in 12 of the 127 vertical profiles. PMID:20577212

  6. Typhoon-induced phytoplankton blooms and primary productivity increase in the western North Pacific subtropical ocean

    NASA Astrophysics Data System (ADS)

    Lin, I.-I.

    2012-03-01

    Using multiple satellite observations and series of numerical experiments, this work systematically studied phytoplankton blooms induced by tropical cyclones in the western North Pacific subtropical ocean (WNPSO) because WNPSO is among the world oceans where most number of intense tropical cyclones are found. All eleven typhoon cases passing the study domain in 2003 were examined in detail. It was observed that only two typhoons (18%) were able to induce phytoplankton blooms (chlorophyll-a concentration increased from ≦0.1 mg m-3 to 0.4-0.8 mg m-3) and strong sea surface temperature cooling of -2.5 to -6°C. The other nine typhoons, including the most intense tropical cyclone on Earth in 2003 (i.e., supertyphoon Maemi), were not able to induce phytoplankton blooms and the associated sea surface temperature cooling was weak (0 to -1.5°C). Using series of numerical experiments, it was found that the presence of warm ocean eddy can effectively isolate the cold, nutrient-rich water to be entrained to the surface ocean. Under this situation, even category 5 typhoon Maemi at its peak intensity of 150 kts could not induce phytoplankton bloom in the WNPSO. The weak responses of the other eight typhoons were due to insufficient wind intensity and transit time (caused by relatively small storm size and fast translation speed) in this deep nutricline/mixed layer ocean. As a result, the total annual primary production increase induced by typhoons in the WNPSO was estimated to be ˜3.27 × 1012 g C (0.00327 Pg), equivalent to 0.15% of the global annual anthropogenic CO2 uptake. This suggests that though WNPSO has the highest number and intensity of tropical cyclones among the world oceans, tropical cyclones in the WNPSO have little contribution to enhance biological carbon fixation in the context of global carbon-climate system.

  7. Microbial community structure and function on sinking particles in the North Pacific Subtropical Gyre

    SciTech Connect

    Fontanez, Kristina M.; Eppley, John M.; Samo, Ty J.; Karl, David M.; DeLong, Edward F.

    2015-05-19

    Sinking particles mediate the transport of carbon and energy to the deep-sea, yet the specific microbes associated with sedimenting particles in the ocean's interior remain largely uncharacterized. In this study, we used particle interceptor traps (PITs) to assess the nature of particle-associated microbial communities collected at a variety of depths in the North Pacific Subtropical Gyre. Comparative metagenomics was used to assess differences in microbial taxa and functional gene repertoires in PITs containing a preservative (poisoned traps) compared to preservative-free traps where growth was allowed to continue in situ (live traps). Live trap microbial communities shared taxonomic and functional similarities with bacteria previously reported to be enriched in dissolved organic matter (DOM) microcosms (e.g., Alteromonas and Methylophaga), in addition to other particle and eukaryote-associated bacteria (e.g., Flavobacteriales and Pseudoalteromonas). Poisoned trap microbial assemblages were enriched in Vibrio and Campylobacterales likely associated with eukaryotic surfaces and intestinal tracts as symbionts, pathogens, or saprophytes. The functional gene content of microbial assemblages in poisoned traps included a variety of genes involved in virulence, anaerobic metabolism, attachment to chitinaceaous surfaces, and chitin degradation. The presence of chitinaceaous surfaces was also accompanied by the co-existence of bacteria which encoded the capacity to attach to, transport and metabolize chitin and its derivatives. Distinctly different microbial assemblages predominated in live traps, which were largely represented by copiotrophs and eukaryote-associated bacterial communities. Predominant sediment trap-assocaited eukaryotic phyla included Dinoflagellata, Metazoa (mostly copepods), Protalveolata, Retaria, and Stramenopiles. In conclusion, these data indicate the central role of eukaryotic taxa in structuring sinking particle microbial assemblages, as well as

  8. Microbial community structure and function on sinking particles in the North Pacific Subtropical Gyre

    DOE PAGESBeta

    Fontanez, Kristina M.; Eppley, John M.; Samo, Ty J.; Karl, David M.; DeLong, Edward F.

    2015-05-19

    Sinking particles mediate the transport of carbon and energy to the deep-sea, yet the specific microbes associated with sedimenting particles in the ocean's interior remain largely uncharacterized. In this study, we used particle interceptor traps (PITs) to assess the nature of particle-associated microbial communities collected at a variety of depths in the North Pacific Subtropical Gyre. Comparative metagenomics was used to assess differences in microbial taxa and functional gene repertoires in PITs containing a preservative (poisoned traps) compared to preservative-free traps where growth was allowed to continue in situ (live traps). Live trap microbial communities shared taxonomic and functional similaritiesmore » with bacteria previously reported to be enriched in dissolved organic matter (DOM) microcosms (e.g., Alteromonas and Methylophaga), in addition to other particle and eukaryote-associated bacteria (e.g., Flavobacteriales and Pseudoalteromonas). Poisoned trap microbial assemblages were enriched in Vibrio and Campylobacterales likely associated with eukaryotic surfaces and intestinal tracts as symbionts, pathogens, or saprophytes. The functional gene content of microbial assemblages in poisoned traps included a variety of genes involved in virulence, anaerobic metabolism, attachment to chitinaceaous surfaces, and chitin degradation. The presence of chitinaceaous surfaces was also accompanied by the co-existence of bacteria which encoded the capacity to attach to, transport and metabolize chitin and its derivatives. Distinctly different microbial assemblages predominated in live traps, which were largely represented by copiotrophs and eukaryote-associated bacterial communities. Predominant sediment trap-assocaited eukaryotic phyla included Dinoflagellata, Metazoa (mostly copepods), Protalveolata, Retaria, and Stramenopiles. In conclusion, these data indicate the central role of eukaryotic taxa in structuring sinking particle microbial assemblages, as

  9. Wind and sunlight shape microbial diversity in surface waters of the North Pacific Subtropical Gyre.

    PubMed

    Bryant, Jessica A; Aylward, Frank O; Eppley, John M; Karl, David M; Church, Matthew J; DeLong, Edward F

    2016-06-01

    Few microbial time-series studies have been conducted in open ocean habitats having low seasonal variability such as the North Pacific Subtropical Gyre (NPSG), where surface waters experience comparatively mild seasonal variation. To better describe microbial seasonal variability in this habitat, we analyzed rRNA amplicon and shotgun metagenomic data over two years at the Hawaii Ocean Time-series Station ALOHA. We postulated that this relatively stable habitat might reveal different environmental factors that influence planktonic microbial community diversity than those previously observed in more seasonally dynamic habitats. Unexpectedly, the data showed that microbial diversity at 25 m was positively correlated with average wind speed 3 to 10 days prior to sampling. In addition, microbial community composition at 25 m exhibited significant correlations with solar irradiance. Many bacterial groups whose relative abundances varied with solar radiation corresponded to taxa known to exhibit strong seasonality in other oceanic regions. Network co-correlation analysis of 25 m communities showed seasonal transitions in composition, and distinct successional cohorts of co-occurring phylogenetic groups. Similar network analyses of metagenomic data also indicated distinct seasonality in genes originating from cyanophage, and several bacterial clades including SAR116 and SAR324. At 500 m, microbial community diversity and composition did not vary significantly with any measured environmental parameters. The minimal seasonal variability in the NPSG facilitated detection of more subtle environmental influences, such as episodic wind variation, on surface water microbial diversity. Community composition in NPSG surface waters varied in response to solar irradiance, but less dramatically than reported in other ocean provinces. PMID:26645474

  10. Particle distributions and dynamics in the euphotic zone of the North Pacific Subtropical Gyre

    NASA Astrophysics Data System (ADS)

    Barone, Benedetto; Bidigare, Robert R.; Church, Matthew J.; Karl, David M.; Letelier, Ricardo M.; White, Angelicque E.

    2015-05-01

    During the summer of 2012, we used laser diffractometry to investigate the temporal and vertical variability of the particle size spectrum (1.25-100 µm in equivalent diameter) in the euphotic zone of the North Pacific Subtropical Gyre. Particles measured with this optical method accounted for ˜40% of the particulate carbon stocks (<202 µm) in the upper euphotic zone (25-75 m), as estimated using an empirical formula to transform particle volume to carbon concentrations. Over the entire vertical layer considered (20-180 m), the largest contribution to particle volume corresponded to particles between 3 and 10 µm in diameter. Although the exponent of a power law parameterization suggested that larger particles had a lower relative abundance than in other regions of the global ocean, this parameter and hence conclusions about relative particle abundance are sensitive to the shape of the size distribution and to the curve fitting method. Results on the vertical distribution of particles indicate that different size fractions varied independently with depth. Particles between 1.25 and 2 µm reached maximal abundances coincident with the depth of the chlorophyll a maximum (averaging 121 ± 10 m), where eukaryotic phytoplankton abundances increased. In contrast, particles between 2 and 20 µm tended to accumulate just below the base of the mixed layer (41 ± 14 m). Variability in particle size tracked changes in the abundance of specific photoautotrophic organisms (measured with flow cytometry and pigment concentration), suggesting that phytoplankton population dynamics are an important control of the spatiotemporal variability in particle concentration in this ecosystem.

  11. Phenology of particle size distributions and primary productivity in the North Pacific subtropical gyre (Station ALOHA)

    NASA Astrophysics Data System (ADS)

    White, Angelicque E.; Letelier, Ricardo M.; Whitmire, Amanda L.; Barone, Benedetto; Bidigare, Robert R.; Church, Matthew J.; Karl, David M.

    2015-11-01

    The particle size distribution (PSD) is a critical aspect of the oceanic ecosystem. Local variability in the PSD can be indicative of shifts in microbial community structure and reveal patterns in cell growth and loss. The PSD also plays a central role in particle export by influencing settling speed. Satellite-based models of primary productivity (PP) often rely on aspects of photophysiology that are directly related to community size structure. In an effort to better understand how variability in particle size relates to PP in an oligotrophic ecosystem, we collected laser diffraction-based depth profiles of the PSD and pigment-based classifications of phytoplankton functional types (PFTs) on an approximately monthly basis at the Hawaii Ocean Time-series Station ALOHA, in the North Pacific subtropical gyre. We found a relatively stable PSD in the upper water column. However, clear seasonality is apparent in the vertical distribution of distinct particle size classes. Neither laser diffraction-based estimations of relative particle size nor pigment-based PFTs was found to be significantly related to the rate of 14C-based PP in the light-saturated upper euphotic zone. This finding indicates that satellite retrievals of particle size, based on particle scattering or ocean color would not improve parameterizations of present-day bio-optical PP models for this region. However, at depths of 100-125 m where irradiance exerts strong control on PP, we do observe a significant linear relationship between PP and the estimated carbon content of 2-20 μm particles.

  12. Microbial community structure and function on sinking particles in the North Pacific Subtropical Gyre.

    PubMed

    Fontanez, Kristina M; Eppley, John M; Samo, Ty J; Karl, David M; DeLong, Edward F

    2015-01-01

    Sinking particles mediate the transport of carbon and energy to the deep-sea, yet the specific microbes associated with sedimenting particles in the ocean's interior remain largely uncharacterized. In this study, we used particle interceptor traps (PITs) to assess the nature of particle-associated microbial communities collected at a variety of depths in the North Pacific Subtropical Gyre. Comparative metagenomics was used to assess differences in microbial taxa and functional gene repertoires in PITs containing a preservative (poisoned traps) compared to preservative-free traps where growth was allowed to continue in situ (live traps). Live trap microbial communities shared taxonomic and functional similarities with bacteria previously reported to be enriched in dissolved organic matter (DOM) microcosms (e.g., Alteromonas and Methylophaga), in addition to other particle and eukaryote-associated bacteria (e.g., Flavobacteriales and Pseudoalteromonas). Poisoned trap microbial assemblages were enriched in Vibrio and Campylobacterales likely associated with eukaryotic surfaces and intestinal tracts as symbionts, pathogens, or saprophytes. The functional gene content of microbial assemblages in poisoned traps included a variety of genes involved in virulence, anaerobic metabolism, attachment to chitinaceaous surfaces, and chitin degradation. The presence of chitinaceaous surfaces was also accompanied by the co-existence of bacteria which encoded the capacity to attach to, transport and metabolize chitin and its derivatives. Distinctly different microbial assemblages predominated in live traps, which were largely represented by copiotrophs and eukaryote-associated bacterial communities. Predominant sediment trap-assocaited eukaryotic phyla included Dinoflagellata, Metazoa (mostly copepods), Protalveolata, Retaria, and Stramenopiles. These data indicate the central role of eukaryotic taxa in structuring sinking particle microbial assemblages, as well as the rapid

  13. Increasing subtropical North Pacific Ocean nitrogen fixation since the Little Ice Age.

    PubMed

    Sherwood, Owen A; Guilderson, Thomas P; Batista, Fabian C; Schiff, John T; McCarthy, Matthew D

    2014-01-01

    The North Pacific subtropical gyre (NPSG) plays a major part in the export of carbon and other nutrients to the deep ocean. Primary production in the NPSG has increased in recent decades despite a reduction in nutrient supply to surface waters. It is thought that this apparent paradox can be explained by a shift in plankton community structure from mostly eukaryotes to mostly nitrogen-fixing prokaryotes. It remains uncertain, however, whether the plankton community domain shift can be linked to cyclical climate variability or a long-term global warming trend. Here we analyse records of bulk and amino-acid-specific (15)N/(14)N isotopic ratios (δ(15)N) preserved in the skeletons of long-lived deep-sea proteinaceous corals collected from the Hawaiian archipelago; these isotopic records serve as a proxy for the source of nitrogen-supported export production through time. We find that the recent increase in nitrogen fixation is the continuation of a much larger, centennial-scale trend. After a millennium of relatively minor fluctuation, δ(15)N decreases between 1850 and the present. The total shift in δ(15)N of -2 per mil over this period is comparable to the total change in global mean sedimentary δ(15)N across the Pleistocene-Holocene transition, but it is happening an order of magnitude faster. We use a steady-state model and find that the isotopic mass balance between nitrate and nitrogen fixation implies a 17 to 27 per cent increase in nitrogen fixation over this time period. A comparison with independent records suggests that the increase in nitrogen fixation might be linked to Northern Hemisphere climate change since the end of the Little Ice Age. PMID:24336216

  14. Physical forcing of nitrogen fixation and diazotroph community structure in the North Pacific subtropical gyre

    NASA Astrophysics Data System (ADS)

    Church, Matthew J.; Mahaffey, Claire; Letelier, Ricardo M.; Lukas, Roger; Zehr, Jonathan P.; Karl, David M.

    2009-06-01

    Dinitrogen (N2) fixing microorganisms (termed diazotrophs) exert important control on the ocean carbon cycle. However, despite increased awareness on the roles of these microorganisms in ocean biogeochemistry and ecology, the processes controlling variability in diazotroph distributions, abundances, and activities remain largely unknown. In this study, we examine 3 years (2004-2007) of approximately monthly measurements of upper ocean diazotroph community structure and rates of N2 fixation at Station ALOHA (22°45'N, 158°W), the field site for the Hawaii Ocean Time-series program in the central North Pacific subtropical gyre (NPSG). The structure of the N2-fixing microorganism assemblage varied widely in time with unicellular N2-fixing microorganisms frequently dominating diazotroph abundances in the late winter and early spring, while filamentous microorganisms (specifically various heterocyst-forming cyanobacteria and Trichodesmium spp.) fluctuated episodically during the summer. On average, a large fraction (˜80%) of the daily N2 fixation was partitioned into the biomass of <10 μm microorganisms. Rates of N2 fixation were variable in time, with peak N2 fixation frequently coinciding with periods when heterocystous N2-fixing cyanobacteria were abundant. During the summer months when sea surface temperatures exceeded 25.2°C and concentrations of nitrate plus nitrite were at their annual minimum, rates of N2 fixation often increased during periods of positive sea surface height anomalies, as reflected in satellite altimetry. Our results suggest mesoscale physical forcing may comprise an important control on variability in N2 fixation and diazotroph community structure in the NPSG.

  15. Microbial community structure and function on sinking particles in the North Pacific Subtropical Gyre

    PubMed Central

    Fontanez, Kristina M.; Eppley, John M.; Samo, Ty J.; Karl, David M.; DeLong, Edward F.

    2015-01-01

    Sinking particles mediate the transport of carbon and energy to the deep-sea, yet the specific microbes associated with sedimenting particles in the ocean's interior remain largely uncharacterized. In this study, we used particle interceptor traps (PITs) to assess the nature of particle-associated microbial communities collected at a variety of depths in the North Pacific Subtropical Gyre. Comparative metagenomics was used to assess differences in microbial taxa and functional gene repertoires in PITs containing a preservative (poisoned traps) compared to preservative-free traps where growth was allowed to continue in situ (live traps). Live trap microbial communities shared taxonomic and functional similarities with bacteria previously reported to be enriched in dissolved organic matter (DOM) microcosms (e.g., Alteromonas and Methylophaga), in addition to other particle and eukaryote-associated bacteria (e.g., Flavobacteriales and Pseudoalteromonas). Poisoned trap microbial assemblages were enriched in Vibrio and Campylobacterales likely associated with eukaryotic surfaces and intestinal tracts as symbionts, pathogens, or saprophytes. The functional gene content of microbial assemblages in poisoned traps included a variety of genes involved in virulence, anaerobic metabolism, attachment to chitinaceaous surfaces, and chitin degradation. The presence of chitinaceaous surfaces was also accompanied by the co-existence of bacteria which encoded the capacity to attach to, transport and metabolize chitin and its derivatives. Distinctly different microbial assemblages predominated in live traps, which were largely represented by copiotrophs and eukaryote-associated bacterial communities. Predominant sediment trap-assocaited eukaryotic phyla included Dinoflagellata, Metazoa (mostly copepods), Protalveolata, Retaria, and Stramenopiles. These data indicate the central role of eukaryotic taxa in structuring sinking particle microbial assemblages, as well as the rapid

  16. Increasing subtropical North Pacific Ocean nitrogen fixation since the Little Ice Age.

    PubMed

    Sherwood, Owen A; Guilderson, Thomas P; Batista, Fabian C; Schiff, John T; McCarthy, Matthew D

    2014-01-01

    The North Pacific subtropical gyre (NPSG) plays a major part in the export of carbon and other nutrients to the deep ocean. Primary production in the NPSG has increased in recent decades despite a reduction in nutrient supply to surface waters. It is thought that this apparent paradox can be explained by a shift in plankton community structure from mostly eukaryotes to mostly nitrogen-fixing prokaryotes. It remains uncertain, however, whether the plankton community domain shift can be linked to cyclical climate variability or a long-term global warming trend. Here we analyse records of bulk and amino-acid-specific (15)N/(14)N isotopic ratios (δ(15)N) preserved in the skeletons of long-lived deep-sea proteinaceous corals collected from the Hawaiian archipelago; these isotopic records serve as a proxy for the source of nitrogen-supported export production through time. We find that the recent increase in nitrogen fixation is the continuation of a much larger, centennial-scale trend. After a millennium of relatively minor fluctuation, δ(15)N decreases between 1850 and the present. The total shift in δ(15)N of -2 per mil over this period is comparable to the total change in global mean sedimentary δ(15)N across the Pleistocene-Holocene transition, but it is happening an order of magnitude faster. We use a steady-state model and find that the isotopic mass balance between nitrate and nitrogen fixation implies a 17 to 27 per cent increase in nitrogen fixation over this time period. A comparison with independent records suggests that the increase in nitrogen fixation might be linked to Northern Hemisphere climate change since the end of the Little Ice Age.

  17. Phenology of particle size distributions and primary productivity in the North Pacific subtropical gyre (Station ALOHA)

    PubMed Central

    Letelier, Ricardo M.; Whitmire, Amanda L.; Barone, Benedetto; Bidigare, Robert R.; Church, Matthew J.; Karl, David M.

    2015-01-01

    Abstract The particle size distribution (PSD) is a critical aspect of the oceanic ecosystem. Local variability in the PSD can be indicative of shifts in microbial community structure and reveal patterns in cell growth and loss. The PSD also plays a central role in particle export by influencing settling speed. Satellite‐based models of primary productivity (PP) often rely on aspects of photophysiology that are directly related to community size structure. In an effort to better understand how variability in particle size relates to PP in an oligotrophic ecosystem, we collected laser diffraction‐based depth profiles of the PSD and pigment‐based classifications of phytoplankton functional types (PFTs) on an approximately monthly basis at the Hawaii Ocean Time‐series Station ALOHA, in the North Pacific subtropical gyre. We found a relatively stable PSD in the upper water column. However, clear seasonality is apparent in the vertical distribution of distinct particle size classes. Neither laser diffraction‐based estimations of relative particle size nor pigment‐based PFTs was found to be significantly related to the rate of 14C‐based PP in the light‐saturated upper euphotic zone. This finding indicates that satellite retrievals of particle size, based on particle scattering or ocean color would not improve parameterizations of present‐day bio‐optical PP models for this region. However, at depths of 100–125 m where irradiance exerts strong control on PP, we do observe a significant linear relationship between PP and the estimated carbon content of 2–20 μm particles. PMID:27812434

  18. Export stoichiometry and migrant-mediated flux of phosphorus in the North Pacific Subtropical Gyre

    NASA Astrophysics Data System (ADS)

    Hannides, Cecelia C. S.; Landry, Michael R.; Benitez-Nelson, Claudia R.; Styles, Renée M.; Montoya, Joseph P.; Karl, David M.

    2009-01-01

    Export processes play a major role in regulating global marine primary production by reducing the efficiency of nutrient cycling and turnover in surface waters. Most studies of euphotic zone export focus on passive fluxes, that is, sinking particles. However, active transport, the vertical transfer of material by migrating zooplankton, can also be an important component of carbon (C) and nitrogen (N) removal from the surface ocean. Here we demonstrate that active transport is an especially important mechanism for phosphorus (P) removal from the euphotic zone at Station ALOHA (Hawaii Ocean Time-series program; 22°45'N, 158°W), a P-stressed site in the North Pacific Subtropical Gyre. Migrant excretions in this region are P-rich (C 51:N 12:P 1) relative to sinking particles (C 250:N 31:P 1), and migrant-mediated P fluxes are almost equal in magnitude (82%) to P fluxes from sediment traps. Migrant zooplankton biomass and therefore the importance of this P removal pathway relative to sinking fluxes has increased significantly over the past 12 years, suggesting that active transport may be a major driving force for enhanced P-limitation of biological production in the NPSG. We further assess the C:N:P composition of zooplankton size fractions at Station ALOHA (C 88:N 18:P 1, on average) and discuss migrant-mediated P export in light of the balance between zooplankton and suspended particle stoichiometries. We conclude that, because active transport is such a large component of the total P flux and significantly impacts ecosystem stoichiometry, export processes involving migrant zooplankton must be included in large-scale efforts to understand biogeochemical cycles.

  19. Differential Assimilation of Inorganic Carbon and Leucine by Prochlorococcus in the Oligotrophic North Pacific Subtropical Gyre

    PubMed Central

    Björkman, Karin M.; Church, Matthew J.; Doggett, Joseph K.; Karl, David M.

    2015-01-01

    The light effect on photoheterotrophic processes in Prochlorococcus, and primary and bacterial productivity in the oligotrophic North Pacific Subtropical Gyre was investigated using 14C-bicarbonate and 3H-leucine. Light and dark incubation experiments were conducted in situ throughout the euphotic zone (0–175 m) on nine expeditions to Station ALOHA over a 3-year period. Photosynthetrons were also used to elucidate rate responses in leucine and inorganic carbon assimilation as a function of light intensity. Taxonomic group and cell-specific rates were assessed using flow cytometric sorting. The light:dark assimilation rate ratios of leucine in the top 150 m were ∼7:1 for Prochlorococcus, whereas the light:dark ratios for the non-pigmented bacteria (NPB) were not significant different from 1:1. Prochlorococcus assimilated leucine in the dark at per cell rates similar to the NPB, with a contribution to the total community bacterial production, integrated over the euphotic zone, of approximately 20% in the dark and 60% in the light. Depth-resolved primary productivity and leucine incorporation showed that the ratio of Prochlorococcus leucine:primary production peaked at 100 m then declined steeply below the deep chlorophyll maximum (DCM). The photosynthetron experiments revealed that, for Prochlorococcus at the DCM, the saturating irradiance (Ek) for leucine incorporation was reached at approximately half the light intensity required for light saturation of 14C-bicarbonate assimilation. Additionally, high and low red fluorescing Prochlorococcus populations (HRF and LRF), co-occurring at the DCM, had similar Ek values for their respective substrates, however, maximum assimilation rates, for both leucine and inorganic carbon, were two times greater for HRF cells. Our results show that Prochlorococcus contributes significantly to bacterial production estimates using 3H-leucine, whether or not the incubations are conducted in the dark or light, and this should be

  20. Anomalous chlorofluorocarbons at the bottom of the eastern subtropical North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Min, D.; Bullister, J. L.; Fine, R. A.; Mecking, S.; Smethie, W. M., Jr.; Swift, J. H.

    2014-12-01

    Chlorofluorocarbons (CFCs) are man-made compounds which have been widely used as decadal-scale transient tracers for ocean circulation and ventilation processes. These compounds have well-known atmospheric histories and solubilities. Information derived from CFC concentration and ratio measurements in the global ocean allows us to infer the past history of deep water formation and the rates of spreading and mixing processes. These tracers have also been extensively used to compare and calibrate large-scale ocean circulation models and to estimate the oceanic uptake of anthropogenic CO2. During the P02 CLIVAR/CO2 Repeat Hydrography section along 30°N in 2004, low but detectable levels (>0.005 picomole kg-1) of CFCs (esp. CFC-12) were unexpectedly observed in deep waters (>3000-4000m) along an extensive area between Hawaii and California in the subtropical North Pacific Ocean. Near-bottom CFC concentrations tended to be higher toward the California outer continental shelf region (i.e. Southern California Borderland Basins or SCBB). Potential analytical errors or sampling contamination possibilities were carefully checked during the expedition. These anomalous bottom CFC features were observed again in the same region during the P02 revisit cruise in 2013 by an independent group. The presence of CFCs at the levels measured is inconsistent with presently understood rates and pathways of deep ventilation processes in this region. Potential mechanisms for generating these anomalous features will be discussed, including: a) previously unknown deep ventilation processes in this region; b) release of CFCs from sunken ships or other objects; c) spreading of high-CFC content deep waters from the SCBB along the continental slope; d) vertical transport of CFCs by adsorption/uptake by sinking particulates (including particulate organic matter and/or plastic debris) originating in the surface ocean and re-release in the bottom waters. Studies of sediment trap, sediment cores

  1. Differential Assimilation of Inorganic Carbon and Leucine by Prochlorococcus in the Oligotrophic North Pacific Subtropical Gyre.

    PubMed

    Björkman, Karin M; Church, Matthew J; Doggett, Joseph K; Karl, David M

    2015-01-01

    The light effect on photoheterotrophic processes in Prochlorococcus, and primary and bacterial productivity in the oligotrophic North Pacific Subtropical Gyre was investigated using (14)C-bicarbonate and (3)H-leucine. Light and dark incubation experiments were conducted in situ throughout the euphotic zone (0-175 m) on nine expeditions to Station ALOHA over a 3-year period. Photosynthetrons were also used to elucidate rate responses in leucine and inorganic carbon assimilation as a function of light intensity. Taxonomic group and cell-specific rates were assessed using flow cytometric sorting. The light:dark assimilation rate ratios of leucine in the top 150 m were ∼7:1 for Prochlorococcus, whereas the light:dark ratios for the non-pigmented bacteria (NPB) were not significant different from 1:1. Prochlorococcus assimilated leucine in the dark at per cell rates similar to the NPB, with a contribution to the total community bacterial production, integrated over the euphotic zone, of approximately 20% in the dark and 60% in the light. Depth-resolved primary productivity and leucine incorporation showed that the ratio of Prochlorococcus leucine:primary production peaked at 100 m then declined steeply below the deep chlorophyll maximum (DCM). The photosynthetron experiments revealed that, for Prochlorococcus at the DCM, the saturating irradiance (E k) for leucine incorporation was reached at approximately half the light intensity required for light saturation of (14)C-bicarbonate assimilation. Additionally, high and low red fluorescing Prochlorococcus populations (HRF and LRF), co-occurring at the DCM, had similar E k values for their respective substrates, however, maximum assimilation rates, for both leucine and inorganic carbon, were two times greater for HRF cells. Our results show that Prochlorococcus contributes significantly to bacterial production estimates using (3)H-leucine, whether or not the incubations are conducted in the dark or light, and this should

  2. Summer phytoplankton blooms in the oligotrophic North Pacific Subtropical Gyre: Historical perspective and recent observations

    NASA Astrophysics Data System (ADS)

    Dore, John E.; Letelier, Ricardo M.; Church, Matthew J.; Lukas, Roger; Karl, David M.

    2008-01-01

    The export of organic matter from the oceanic euphotic zone is a critical process in the global biogeochemical cycling of bioelements (C, N, P, Si). Much of this export occurs in the form of sinking particles, which rain down into the unlit waters of the deep sea. Classical models of oceanic production and export balance this gravitational loss of particulate bioelements with an upward flux of dissolved nutrients, and they describe reasonably well those areas of the ocean where deep winter mixing occurs. The surface waters of the North Pacific Subtropical Gyre (NPSG), however, are strongly stratified and chronically nutrient-depleted, especially in summer. Nevertheless, there is ample evidence that blooms of phytoplankton and subsequent pulses of particle export occur during the height of summer stratification in these waters, especially to the northeast of the Hawaiian Islands. These blooms impact regional bioelemental cycling and act as a food source to the deep-sea benthos. We review here numerous published observations of these events in the NPSG, and present new data collected at Station ALOHA (22.75°N, 158°W) during the first 176 cruises of the Hawaii Ocean Time-series program (1988-2005), along with results from transect cruises conducted in the region in 1996 and 2005. We suggest that the summer phytoplankton bloom can be considered a frequent, perhaps annual feature in the northeastern NPSG, and that its perceived stochastic nature is a manifestation of chronic undersampling in time and space. The bloom is typically dominated by only a few genera of large diatoms and the cyanobacterium Trichodesmium. It appears to be consistently supported by dinitrogen fixation, but the fate of the organic matter produced during the summer depends critically on the species composition of the responsible diazotrophs. We estimate that the summer bloom is responsible for up to 38% of N 2 fixation and up to 18% of N-based new production annually at Station ALOHA. We

  3. Air-sea carbon dioxide exchange in the North Pacific subtropical Gyre: Implications for the global carbon budget

    SciTech Connect

    Winn, C.D.; Mackenzie, F.T.; Carrillo, C.J.; Karl, D.M. ); Sabine, C.L. )

    1994-06-01

    After 20 years of investigation the scientific community has been unable to resolve the magnitudes and direction of carbon dioxide fluxes involving oceans and terrestrial biomass. Studies of the authors over the last four years measuring inorganic carbon parameters suggest that the North Pacific Subtropical Cyre (NPSG) is a sink for atmospheric carbon dioxide. This paper presents a mechanism by which the NPSG can be a net sink for atmospheric carbon dioxide and the magnitude of this sink is calculated as approximately 0.2 Gt C yr. The authors note that this sink is still approximately an order of magnitude smaller than that needed to balance the global carbon budget. 41 refs., 3 figs., 1 tab.

  4. Millennial-scale plankton regime shifts in the subtropical North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    McMahon, Kelton W.; McCarthy, Matthew D.; Sherwood, Owen A.; Larsen, Thomas; Guilderson, Thomas P.

    2015-12-01

    Climate change is predicted to alter marine phytoplankton communities and affect productivity, biogeochemistry, and the efficacy of the biological pump. We reconstructed high-resolution records of changing plankton community composition in the North Pacific Ocean over the past millennium. Amino acid-specific δ13C records preserved in long-lived deep-sea corals revealed three major plankton regimes corresponding to Northern Hemisphere climate periods. Non-dinitrogen-fixing cyanobacteria dominated during the Medieval Climate Anomaly (950-1250 Common Era) before giving way to a new regime in which eukaryotic microalgae contributed nearly half of all export production during the Little Ice Age (~1400-1850 Common Era). The third regime, unprecedented in the past millennium, began in the industrial era and is characterized by increasing production by dinitrogen-fixing cyanobacteria. This picoplankton community shift may provide a negative feedback to rising atmospheric carbon dioxide concentrations.

  5. Millennial-scale plankton regime shifts in the subtropical North Pacific Ocean.

    PubMed

    McMahon, Kelton W; McCarthy, Matthew D; Sherwood, Owen A; Larsen, Thomas; Guilderson, Thomas P

    2015-12-18

    Climate change is predicted to alter marine phytoplankton communities and affect productivity, biogeochemistry, and the efficacy of the biological pump. We reconstructed high-resolution records of changing plankton community composition in the North Pacific Ocean over the past millennium. Amino acid-specific δ(13)C records preserved in long-lived deep-sea corals revealed three major plankton regimes corresponding to Northern Hemisphere climate periods. Non-dinitrogen-fixing cyanobacteria dominated during the Medieval Climate Anomaly (950-1250 Common Era) before giving way to a new regime in which eukaryotic microalgae contributed nearly half of all export production during the Little Ice Age (~1400-1850 Common Era). The third regime, unprecedented in the past millennium, began in the industrial era and is characterized by increasing production by dinitrogen-fixing cyanobacteria. This picoplankton community shift may provide a negative feedback to rising atmospheric carbon dioxide concentrations. PMID:26612834

  6. Millennial-scale plankton regime shifts in the subtropical North Pacific Ocean.

    PubMed

    McMahon, Kelton W; McCarthy, Matthew D; Sherwood, Owen A; Larsen, Thomas; Guilderson, Thomas P

    2015-12-18

    Climate change is predicted to alter marine phytoplankton communities and affect productivity, biogeochemistry, and the efficacy of the biological pump. We reconstructed high-resolution records of changing plankton community composition in the North Pacific Ocean over the past millennium. Amino acid-specific δ(13)C records preserved in long-lived deep-sea corals revealed three major plankton regimes corresponding to Northern Hemisphere climate periods. Non-dinitrogen-fixing cyanobacteria dominated during the Medieval Climate Anomaly (950-1250 Common Era) before giving way to a new regime in which eukaryotic microalgae contributed nearly half of all export production during the Little Ice Age (~1400-1850 Common Era). The third regime, unprecedented in the past millennium, began in the industrial era and is characterized by increasing production by dinitrogen-fixing cyanobacteria. This picoplankton community shift may provide a negative feedback to rising atmospheric carbon dioxide concentrations.

  7. Zooplankton abundance, biovolume and size spectra at western boundary currents in the subtropical North Pacific during winter 2012

    NASA Astrophysics Data System (ADS)

    Dai, Luping; Li, Chaolun; Yang, Guang; Sun, Xiaoxia

    2016-03-01

    Horizontal changes in mesozooplankton abundance, biovolume and size spectra at western boundary currents in the subtropical North Pacific during winter 2012 were evaluated by ZooScan measurement on samples collected by net towing from 23 stations. Zooplankton abundance and biovolume ranged from 35.1 to 456.8 ind. m- 3 and 4.3 to 231.7 mm3 m- 3, respectively. Copepoda were the most dominant species, followed by Chaetognatha and Tunicata. According to the Bray-Curtis cluster analysis based on biovolume of zooplankton size classes of each taxonomic group at intervals of 1 (log2 mm3 ind.- 1) between - 6 and 12 and considering the effect of regional factors, zooplankton communities were classified into four groups, which basically coincided with the geographical patterns of different currents: the North Equatorial Current (NEC), the North Equatorial Counter Current (NECC), the Kuroshio Current (KC), and the Mindanao Eddy (ME), respectively. The largest and lowest biovolumes were observed in the NECC region and the NEC region, respectively, and both were dominated by the 0.3 to 1 mm equivalent spherical diameter (ESD) size class, while the ME region was dominant by the 1 to 2 mm ESD size class. The slopes of the normalized biovolume size spectra for each group were slightly lower than - 1 (range from - 0.85 to - 0.92), which indicates that zooplankton communities in the study area were characterized by low productivity and high energy transfer efficiency.

  8. Non-cyanobacterial nifH phylotypes in the North Pacific Subtropical Gyre detected by flow-cytometry cell sorting.

    PubMed

    Bombar, Deniz; Turk-Kubo, Kendra A; Robidart, Julie; Carter, Brandon J; Zehr, Jonathan P

    2013-10-01

    In contrast to cyanobacteria, the significance of bacteria and archaea in oceanic N2 fixation remains unknown, apart from the knowledge that their nitrogenase (nifH) genes are diverse, present in all oceans and at least occasionally expressed. Non-cyanobacterial nifH sequences often occur as contamination from reagents and other sources, complicating the detection and interpretation of environmental phylotypes. We amplified and sequenced partial nifH gene fragments directly from cell populations sorted by fluorescence activated cell sorting from water collected in the North Pacific Subtropical Gyre (NPSG). Sequences recovered (195 total) included presumed heterotrophic or photoheterotrophic non-cyanobacterial nifH phylotypes previously unreported in the NPSG. A nifH sequence previously found in the South Pacific Gyre (HM210397) was exclusively recovered from sorted picoeukaryote populations, and was detected in water column samples using quantitative PCR (qPCR), with 60% of samples detected in the > 10 μm size fraction in addition to the 0.2-10 μm size fraction. A novel cluster 3-like nifH sequence was also recovered from discrete cell sorts and detected by qPCR in environmental samples. This approach enables the detection of rare nifH phylotypes, identifies possible associations with larger cells or particles and offers a possible solution for distinguishing reagent contaminants from real microbial community components. PMID:24115621

  9. Effect of horizontal grid resolution on simulations of the subtropical mode water in the North Pacific

    NASA Astrophysics Data System (ADS)

    Lee, Ho Jin; Yeop Kim, Sang; Lee, Kyung Eun

    2016-04-01

    We investigate how the Subtopical Mode Water (STMW) can be simulated differently in the North Pacific using a global Ocean General Circulation Model (OGCM) with non-eddying and eddy permitting resolution. The OGCM used in this study is the MOM version 4.1 and has a total of 50 levels along the vertical direction with enhanced resolution near the surface. The CORE version 2 (normal year forcing) data derived from the air-sea flux climatology averaged over 60 years (1948‑2007) are used to calculate heat, salt and momentum fluxes with a bulk formula at the sea surface. The sea surface salinity is restored to the climatological monthly mean surface salinity of the Polar Science Center Hydrographic Climatology on a 60-day timescale, to make up the fresh water flux at the sea surface. Two models that have horizontal resolutions of 1° and 1/4 °, respectively, are integrated during 50 years. The inter-annual variation of the STMW volume was well reproduced with the eddy-permitting grid resolution although the model was forced by a climatological atmospheric forcing. The annual formation and erosion volume of STMW varies by 7% and 9% of the mean volume, respectively.

  10. Dissolved hydrogen and nitrogen fixation in the oligotrophic North Pacific Subtropical Gyre.

    PubMed

    Wilson, Samuel T; del Valle, Daniela A; Robidart, Julie C; Zehr, Jonathan P; Karl, David M

    2013-10-01

    The production of hydrogen (H2) is an inherent component of biological dinitrogen (N2) fixation, and there have been several studies quantifying H2 production relative to N2 fixation in cultures of diazotrophs. However, conducting the relevant measurements for a field population is more complex as shown by this study of N2 fixation, H2 consumption and dissolved H2 concentrations in the oligotrophic North Pacific Ocean. Measurements of H2 oxidation revealed microbial consumption of H2 was equivalent to 1-7% of ethylene produced during the acetylene reduction assay and 11-63% of (15)N2 assimilation on a molar scale. Varying abundances of Crocosphaera and Trichodesmium as revealed by nifH gene abundances broadly corresponded with diel changes observed in both N2 fixation and H2 oxidation. However, no corresponding changes were observed in the dissolved H2 concentrations which remained consistently supersaturated (147-560%) relative to atmospheric equilibrium. The results from this field study allow the efficiency of H2 cycling by natural populations of diazotrophs to be compared to cultured representatives. The findings indicate that dissolved H2 concentrations may depend not only on the community composition of diazotrophs but also upon relevant environmental parameters such as light intensity or the presence of other H2-metabolizing microorganisms. PMID:24115620

  11. Dissolved hydrogen and nitrogen fixation in the oligotrophic North Pacific Subtropical Gyre.

    PubMed

    Wilson, Samuel T; del Valle, Daniela A; Robidart, Julie C; Zehr, Jonathan P; Karl, David M

    2013-10-01

    The production of hydrogen (H2) is an inherent component of biological dinitrogen (N2) fixation, and there have been several studies quantifying H2 production relative to N2 fixation in cultures of diazotrophs. However, conducting the relevant measurements for a field population is more complex as shown by this study of N2 fixation, H2 consumption and dissolved H2 concentrations in the oligotrophic North Pacific Ocean. Measurements of H2 oxidation revealed microbial consumption of H2 was equivalent to 1-7% of ethylene produced during the acetylene reduction assay and 11-63% of (15)N2 assimilation on a molar scale. Varying abundances of Crocosphaera and Trichodesmium as revealed by nifH gene abundances broadly corresponded with diel changes observed in both N2 fixation and H2 oxidation. However, no corresponding changes were observed in the dissolved H2 concentrations which remained consistently supersaturated (147-560%) relative to atmospheric equilibrium. The results from this field study allow the efficiency of H2 cycling by natural populations of diazotrophs to be compared to cultured representatives. The findings indicate that dissolved H2 concentrations may depend not only on the community composition of diazotrophs but also upon relevant environmental parameters such as light intensity or the presence of other H2-metabolizing microorganisms.

  12. Relationship between the seasonal change in fluorescent dissolved organic matter and mixed layer depth in the subtropical western North Pacific

    NASA Astrophysics Data System (ADS)

    Omori, Yuko; Hama, Takeo; Ishii, Masao; Saito, Shu

    2010-06-01

    Spatial and temporal distributions of marine humic-like fluorescent dissolved organic matter (FDOMM) were determined in the subtropical western North Pacific to evaluate the controlling factors of FDOMM behaviors. The observations were conducted at 4 stations (15-30°N) along 137°E in a subtropical area between January 2006 and April 2007. The florescence intensity of FDOMM was low (0.14-0.25 quinine sulfate units (QSU)) in the surface layer probably due to photodegradation, and increased with depth (0.90-1.10 QSU at 1000 m), irrespective of season and station. In the surface layer, the thickness of the water mass with low fluorescence intensity (<0.3 QSU) showed the seasonal change by being deeper in winter and shallower in summer, depending on the mixed layer depth (MLD). The average fluorescence intensity within the mixed layer also varied seasonally at midlatitudes; the intensity in summer was 40.8-53.8% of that in winter. Since the MLD was very much shallower in summer than in winter, FDOMM in the mixed layer would be kept within a shallow depth during the summer where intensive photodegradation could occur. The concentration of total organic carbon (TOC) was at its maximum at the water surface and decreased with depth, being adverse to FDOMM. Thus, the ratio of fluorescence intensity to TOC concentration was lowest (0.002-0.003) in surface water, which implies that FDOMM is not quantitatively important to the dissolved organic carbon pool. However, considering the possible difference in the stabilities of FDOMM against photochemical and microbial degradation, it is conceivable that photobleached FDOMM is one of the important organic groups constituting marine dissolved organic matter.

  13. Constraints on nitrogen cycling at the subtropical North Pacific Station ALOHA from isotopic measurements of nitrate and particulate nitrogen

    NASA Astrophysics Data System (ADS)

    Casciotti, K. L.; Trull, T. W.; Glover, D. M.; Davies, D.

    2008-07-01

    Nitrogen supply to surface waters can play an important role in the productivity and ecology of subtropical ecosystems. As part of the Vertical Transport in the Global Ocean (VERTIGO) program, we examined the fluxes of nitrogen into and out of the euphotic zone at station ALOHA in the North Pacific Subtropical Gyre using natural abundance stable isotopic measurements of nitrate ( δN and δO), as well as sinking and suspended particulate nitrogen (δ 15N PN). Paralleling the steep gradient in nitrate concentration in the upper thermocline at ALOHA, we observed a steep gradient in δN, decreasing from a maximum of +7.1‰ at 500 meters (m) to +1.5-2.4‰ at 150 m. δO values also decreased from +3.0‰ at 300 m to +0.7-0.9‰ at 150 m. The decreases in both δN and δO require inputs of isotopically "light" nitrate to balance the upward flux of nitrate with high δN (and δO). We conclude that both nitrogen fixation and diagenetic alteration of the sinking flux contribute to the decrease in δN and δO in the upper thermocline at station ALOHA. While nitrogen fixation is required to explain the nitrogen isotope patterns, the rates of nitrogen fixation may be lower than previously estimated. By including high-resolution nitrate isotope measurements in the nitrogen isotope budget for the euphotic zone at ALOHA, we estimate that approximately 25%, rather than 50%, of export production was fueled by N 2 fixation during our study. On the other hand, this input of N 2-derived production accumulates in the upper thermocline over time, playing a significant role in subtropical nutrient cycling through maintenance of the subsurface nitrate pool. An increase in sinking δ 15N PN between 150 and 300 m, also suggests that fractionation during remineralization contributed to the low δN values observed in this depth range by introducing a subsurface nitrate source that is 0.5‰ lower in δ 15N than the particle flux exported from the euphotic zone. While the time scale of these

  14. Distribution depth of the transforming stage larvae of myctophid fishes in the subtropical tropical waters of the western North Pacific

    NASA Astrophysics Data System (ADS)

    Sassa, Chiyuki; Kawaguchi, Kouichi; Hirota, Yuichi; Ishida, Minoru

    2007-12-01

    We describe the day-night vertical distribution patterns of 18 species or types of myctophid fish larvae at the transforming stage based on discrete depth sampling from the surface down to 1000-m depth in the subtropical-tropical western North Pacific. A total of 551 transforming stage larvae were collected at the 19 sampling stations. Except for the Diaphus species and Notolychnus valdiviae, all of the transforming stage larvae (including genera Benthosema, Bolinichthys, Centrobranchus, Ceratoscopelus, Diogenichthys, Hygophum, Lampanyctus, Lobianchia, Myctophum, Symbolophorus, and Triphoturus) were collected in the lower mesopelagic zone from 600- to 900-m depth during both day and night, showing no diel vertical migration (DVM). On the contrary, the Diaphus species and N. valdiviae larvae undergo DVM during the transforming stage, occurring below 200-m layer during the daytime and migrating up to the upper 150-m layer at night, i.e., they show earlier adaptation to juvenile-adult behaviors. Most myctophid fish larvae are known to undertake substantial ontogenetic vertical migration (OVM) from the epipelagic to mesopelagic zones during their early life stage. Although considerable sampling effort was carried out in this study, transforming larvae, except for the above two migratory ones, were not collected in the epipelagic and upper mesopelagic zones, strongly suggesting that their sinking speed would be high. It would be advantageous for survival to spend their highly vulnerable transforming stage in the lower mesopelagic zone, where predation pressures are lower and physical conditions are more stable than in the upper layers.

  15. A comparison of mesopelagic mesozooplankton community structure in the subtropical and subarctic North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Steinberg, Deborah K.; Cope, Joseph S.; Wilson, Stephanie E.; Kobari, T.

    2008-07-01

    Mesopelagic mesozooplankton communities of an oligotrophic (Hawaii Ocean Time series-HOT station ALOHA) and a mesotrophic (Japanese time-series station K2) environment in the North Pacific Ocean are compared as part of a research program investigating the factors that control the efficiency of particle export to the deep sea (VERtical Transport In the Global Ocean—VERTIGO). We analyzed zooplankton (>350 μm) collected from net tows taken between 0 and 1000 m at each site to investigate the biomass size structure and the abundance of the major taxonomic groups in discrete depth intervals throughout the water column. Biomass of zooplankton at K2 over all depths was approximately an order of a magnitude higher than at ALOHA, with a significantly higher proportion of the biomass at K2 in the larger (>2 mm) size classes. This difference was mostly due to the abundance at K2 of the large calanoid copepods Neocalanus spp. and Eucalanus bungii, which undergo ontogenetic (seasonal) vertical migration. The overall strength of diel vertical migration was higher at K2, with a mean night:day biomass ratio in the upper 150 m of 2.5, vs. a ratio of 1.7 at ALOHA. However, the amplitude of the diel migration (change in weighted mean depth between day and night) was higher at ALOHA for all biomass size classes, perhaps due to deeper light penetration causing deeper migration to avoid visual predators. A number of taxa known to feed on suspended or sinking detritus showed distinct peaks in the mesopelagic zone, which affects particle transport efficiency at both sites. These taxa include calanoid and poecilostomatoid (e.g., Oncaea spp.) copepods, salps, polychaetes, and phaeodarian radiolaria at K2, harpacticoid copepods at ALOHA, and ostracods at both sites. We found distinct layers of carnivores (mainly gelatinous zooplankton) in the mesopelagic at K2 including chaetognaths, hydrozoan medusae, polychaetes, and gymnosome pteropods, and, in the upper mesopelagic zone, of

  16. Use of Satellite-Derived Water Vapor Data to Investigate Northwestward Expansion of North Pacific Subtropical High During 1995 Summer: Westward Propagating Moisture Pattern

    NASA Technical Reports Server (NTRS)

    Sohn, Byung-Ju; Chung, Hyo-Sang; Kim, Do-Hyung; Perkey, Donald; Robertson, Franklin R.; Smith, Eric A.; Arnold, James E. (Technical Monitor)

    2001-01-01

    The spatial and temporal evolution of the moisture field over the subtropical northwest Pacific during the summer of 1995 is investigated using daily total precipitable water from combined SSM/I-TOVS data and pentad upper tropospheric humidity (UTH) data, in conjunction with NCEP reanalysis data. From analysis of the combined water vapor field, the westward movement of a dry airmass is observed along the 20-30 degrees N latitude zone from near the dateline to the south of Japan throughout the summer of 1995. Extended EOF analysis of total precipitable water reveals that the westward moving pattern takes place in conjunction with an expanding North Pacific subtropical high maintaining an oscillatory component exhibiting a period of some 15-25 days. A concomitant dipole-like oscillating anomalous circulation with approximately a 20-day period between the South China Sea and south of Japan appears to influence the westward expansion of the subtropical high. The analysis also suggests that the fluctuations of the North Pacific high are in response to a local Hadley-type circulation which is induced by westward-moving anomalous convection episodes along 10-20 degrees N.

  17. Experimental assessment of diazotroph responses to elevated seawater pCO2 in the North Pacific Subtropical Gyre

    NASA Astrophysics Data System (ADS)

    Böttjer, Daniela; Karl, David M.; Letelier, Ricardo M.; Viviani, Donn A.; Church, Matthew J.

    2014-06-01

    We examined short-term (24-72 h) responses of naturally occurring marine N2 fixing microorganisms (termed diazotrophs) to abrupt increases in the partial pressure of carbon dioxide (pCO2) in seawater during nine incubation experiments conducted between May 2010 and September 2012 at Station ALOHA (A Long-term Oligotrophic Habitat Assessment) (22°45'N, 158°W) in the North Pacific Subtropical Gyre (NPSG). Rates of N2 fixation, nitrogenase (nifH) gene abundances and transcripts of six major groups of cyanobacterial diazotrophs (including both unicellular and filamentous phylotypes), and rates of primary productivity (as measured by 14C-bicarbonate assimilation into plankton biomass) were determined under contemporary (~390 ppm) and elevated pCO2 conditions (~1100 ppm). Quantitative polymerase chain reaction (QPCR) amplification of planktonic nifH genes revealed that unicellular cyanobacteria phylotypes dominated gene abundances during these experiments. In the majority of experiments (seven out of nine), elevated pCO2 did not significantly influence rates of dinitrogen (N2) fixation or primary productivity (two-way analysis of variance (ANOVA), P > 0.05). During two experiments, rates of N2 fixation and primary productivity were significantly lower (by 79 to 82% and 52 to 72%, respectively) in the elevated pCO2 treatments relative to the ambient controls (two-way ANOVA, P < 0.05). QPCR amplification of nifH genes and gene transcripts revealed that diazotroph abundances and nifH gene expression were largely unchanged by the perturbation of the seawater pCO2. Our results suggest that naturally occurring N2 fixing plankton assemblages in the NPSG are relatively resilient to large, short-term increases in pCO2.

  18. Microbial group specific uptake kinetics of inorganic phosphate and adenosine-5'-triphosphate (ATP) in the north pacific subtropical gyre.

    PubMed

    Björkman, Karin; Duhamel, Solange; Karl, David M

    2012-01-01

    We investigated the concentration dependent uptake of inorganic phosphate (Pi) and adenosine-5'-triphosphate (ATP) in microbial populations in the North Pacific Subtropical Gyre (NPSG). We used radiotracers to measure substrate uptake into whole water communities, differentiated microbial size classes, and two flow sorted groups; Prochlorococcus (PRO) and non-pigmented bacteria (NPB). The Pi concentrations, uptake rates, and Pi pool turnover times (Tt) were (mean, ±SD); 54.9 ± 35.0 nmol L(-1) (n = 22), 4.8 ± 1.9 nmol L(-1) day(-1) (n = 19), and 14.7 ± 10.2 days (n = 19), respectively. Pi uptake into >2 μm cells was on average 12 ± 7% (n = 15) of the total uptake. The kinetic response to Pi (10-500 nmol L(-1)) was small, indicating that the microorganisms were close to their maximum uptake velocity (V(max)). V(max) averaged 8.0 ± 3.6 nmol L(-1) day(-1) (n = 19) in the >0.2 μm group, with half saturation constants (K(m)) of 40 ± 28 nmol L(-1) (n = 19). PRO had three times the cell specific Pi uptake rate of NPB, at ambient concentrations, but when adjusted to cells L(-1) the rates were similar, and these two groups were equally competitive for Pi. The Tt of γ-P-ATP in the >0.2 μm group were shorter than for the Pi pool (4.4 ± 1.0 days; n = 6), but this difference diminished in the larger size classes. The kinetic response to ATP was large in the >0.2 μm class with V(max) exceeding the rates at ambient concentrations (mean 62 ± 27 times; n = 6) with a mean V(max) for γ-P-ATP of 2.8 ± 1.0 nmol L(-1) day(-1), and K(m) at 11.5 ± 5.4 nmol L(-1) (n = 6). The NPB contribution to γ-P-ATP uptake was high (95 ± 3%, n = 4) at ambient concentrations but decreased to ∼50% at the highest ATP amendment. PRO had K(m) values 5-10 times greater than NPB. The above indicates that PRO and NPB were in close competition in terms of Pi

  19. Feeding ecology of mesopelagic zooplankton of the subtropical and subarctic North Pacific Ocean determined with fatty acid biomarkers

    NASA Astrophysics Data System (ADS)

    Wilson, S. E.; Steinberg, D. K.; Chu, F.-L. E.; Bishop, J. K. B.

    2010-10-01

    Mesopelagic zooplankton may meet their nutritional and metabolic requirements in a number of ways including consumption of sinking particles, carnivory, and vertical migration. How these feeding modes change with depth or location, however, is poorly known. We analyzed fatty acid (FA) profiles to characterize zooplankton diet and large particle (>51 μm) composition in the mesopelagic zone (base of euphotic zone -1000 m) at two contrasting time-series sites in the subarctic (station K2) and subtropical (station ALOHA) Pacific Ocean. Total FA concentration was 15.5 times higher in zooplankton tissue at K2, largely due to FA storage by seasonal vertical migrators such as Neocalanus and Eucalanus. FA biomarkers specific to herbivory implied a higher plant-derived food source at mesotrophic K2 than at oligotrophic ALOHA. Zooplankton FA biomarkers specific to dinoflagellates and diatoms indicated that diatoms, and to a lesser extent, dinoflagellates were important food sources at K2. At ALOHA, dinoflagellate FAs were more prominent. Bacteria-specific FA biomarkers in zooplankton tissue were used as an indicator of particle feeding, and peaks were recorded at depths where known particle feeders were present at ALOHA (e.g., ostracods at 100-300 m). In contrast, depth profiles of bacterial FA were relatively constant with depth at K2. Diatom, dinoflagellate, and bacterial biomarkers were found in similar proportions in both zooplankton and particles with depth at both locations, providing additional evidence that mesopelagic zooplankton consume sinking particles. Carnivory indices were higher and increased significantly with depth at ALOHA, and exhibited distinct peaks at K2, representing an increase in dependence on other zooplankton for food in deep waters. Our results indicate that feeding ecology changes with depth as well as by location. These changes in zooplankton feeding ecology from the surface through the mesopelagic zone, and between contrasting environments

  20. Heterotrophic prokaryote distribution along a 2300 km transect in the North Pacific subtropical gyre during strong La Niña conditions: relationship between distribution and hydrological conditions

    NASA Astrophysics Data System (ADS)

    Girault, M.; Arakawa, H.; Barani, A.; Ceccaldi, H. J.; Hashihama, F.; Gregori, G.

    2014-11-01

    The spatial distribution of heterotrophic prokaryotes was investigated during the Tokyo-Palau cruise in the western part of the North Pacific subtropical gyre (NPSG) along a north-south transect between 33.60 and 13.25° N. The cruise was conducted in three different hydrological areas identified as the Kuroshio region, the Subtropical gyre area and the Transition zone. Two eddies were crossed along the transect: one cold core cyclonic eddy and one warm core anticyclonic eddy and distributions of the heterotrophic prokaryotes were recorded. By using analytical flow cytometry and a nucleic acid staining protocol, heterotrophic prokaryotes were discriminated into three subgroups depending on their nucleic acid content (low, high and very high nucleic acid contents labeled LNA, HNA and VHNA, respectively). Statistical analyses performed on the dataset showed that LNA, mainly associated with temperature and salinity, were dominant in all the hydrological regions. In contrast, HNA distribution seemed to be associated with temperature, salinity, Chl a and silicic acid. A latitudinal increase in the HNA / LNA ratio was observed along the north-south transect and was related to higher phosphate and nitrate concentrations. In the Kuroshio Current, it is suggested that the high concentration of heterotrophic prokaryotes observed at station 4 was linked to the path of the cold cyclonic eddy core. In contrast, it is thought that low concentrations of heterotrophic prokaryotes in the warm core of the anticyclonic gyre (Sta. 9) are related to the low nutrient concentrations measured in the seawater column. Our results showed that the high variability between the various heterotrophic prokaryote cluster abundances depend both on the mesoscale structures and the oligotrophic gradient.

  1. Distribution of sei whales (Balaenoptera borealis) in the subarctic-subtropical transition area of the western North Pacific in relation to oceanic fronts

    NASA Astrophysics Data System (ADS)

    Murase, Hiroto; Hakamada, Takashi; Matsuoka, Koji; Nishiwaki, Shigetoshi; Inagake, Denzo; Okazaki, Makoto; Tojo, Naoki; Kitakado, Toshihide

    2014-09-01

    The subarctic-subtropical transition area of the western North Pacific is an important summer feeding grounds of sei whales. The oceanographic structure and circulation of this area are largely determined by strong oceanic fronts and associated geostrophic currents, namely the Polar Front (PF), Subarctic Front (SAF) and Kuroshio Extension Front (KEF). The relationship between the distribution of sei whales and oceanographic fronts was investigated using a generalized additive model (GAM), and the cetacean sighting survey data and oceanographic observations in July from 2000 to 2007 were used in the analysis. The number of individual sei whales was used as the response variable while the distances from the PF, SAF, and KEF to the whales were used as explanatory variables along with the longitude values. Sei whales were concentrated north and south of the SAF and the areas from 250 to 300 km north and from 100 to 200 km south of the SAF were estimated as high-density areas of sei whales. The entire inter-frontal zone between the PF and SAF featured an elevated concentration of sei whales, and the area south of the PF and along the SAF was identified as an important feeding ground of sei whales in July from 2000 to 2007.

  2. Dynamics of the SAR11 bacterioplankton lineage in relation to environmental conditions in the oligotrophic North Pacific subtropical gyre.

    PubMed

    Eiler, Alexander; Hayakawa, Darin H; Church, Matthew J; Karl, David M; Rappé, Michael S

    2009-09-01

    A quantitative PCR assay for the SAR11 clade of marine Alphaproteobacteria was applied to nucleic acids extracted from monthly depth profiles sampled over a 3-year period (2004-2007) at the open-ocean Station ALOHA (A Long-term Oligotrophic Habitat Assessment; 22 degrees 45'N, 158 degrees 00'W) in the oligotrophic North Pacific Ocean. This analysis revealed a high contribution (averaging 36% of 16S rRNA gene copies) of SAR11 to the total detected 16S rRNA gene copies over depths ranging from the surface layer to 4000 m, and revealed consistent spatial and temporal variation in the relative abundance of SAR11 16S rRNA gene copies. On average, a higher proportion of SAR11 rRNA gene copies were detected in the photic zone (< 175 m depth; mean = 38%) compared with aphotic (> 175 m depth; mean = 30%), and in the winter months compared with the summer (mean = 44% versus 33%, integrated over 175 m depth). Partial least square to latent structure projections identified environmental variables that correlate with variation in the absolute abundance of SAR11, and provided tools for developing a predictive model to explain time and depth-dependent variations in SAR11. Moreover, this information was used to hindcast temporal dynamics of the SAR11 clade between 1997 and 2006 using the existing HOT data set, which suggested that interannual variations in upper ocean SAR11 abundances were related to ocean-climate variability such as the El Niño Southern Oscillation.

  3. Silicate:nitrate ratios of upwelled waters control the phytoplankton community sustained by mesoscale eddies in sub-tropical North Atlantic and Pacific

    NASA Astrophysics Data System (ADS)

    Bibby, T. S.; Moore, C. M.

    2011-03-01

    Mesoscale eddies in sub-tropical gyres physically perturb the water column and can introduce macronutrients to the euphotic zone, stimulating a biological response in which phytoplankton communities can become dominated by large phytoplankton. Mesoscale eddies may therefore be important in driving export in oligotrophic regions of the modern ocean. However, the character and magnitude of the biological response sustained by eddies is variable. Here we present data from mesoscale eddies in the Sargasso Sea (Atlantic) and the waters off Hawai'i (Pacific), alongside mesoscale events that affected the Bermuda Atlantic Time-Series Study (BATS) over the past decade. From this analysis, we suggest that the phytoplankton community structure sustained by mesoscale eddies is predetermined by the relative abundance of silicate over nitrate (Si*) in the upwelled waters. We present data that demonstrate that mode-water eddies (MWE) in the Sargasso Sea upwell locally formed waters with relatively high Si* to the euphotic zone, and that cyclonic eddies in the Sargasso Sea introduce waters with relatively low Si*, a signature that originated in the iron-limited Southern Ocean. We propose that this phenomenon can explain the observed dominance of the phytoplankton community by large-diatom species in MWE and by small prokaryotic phytoplankton in cyclonic features. In contrast to the Atlantic, North Pacific Intermediate Water (NPIW) with high Si* may influence the cyclonic eddies in waters off Hawai'i, which also appear capable of sustaining diatom populations. These observations suggest that the structure of phytoplankton communities sustained by eddies may be related to the chemical composition of the upwelled waters in addition to the physical nature of the eddy.

  4. Silicate:nitrate ratios of upwelled waters control the phytoplankton community sustained by mesoscale eddies in sub-tropical North Atlantic and Pacific

    NASA Astrophysics Data System (ADS)

    Bibby, T. S.; Moore, C. M.

    2010-10-01

    Mesoscale eddies in sub-tropical gyres physically perturb the water column and can introduce macronutrients to the euphotic zone, stimulating a biological response by which phytoplankton communities can become dominated by large phytoplankton. Mesoscale eddies are therefore important in driving export in oligotrophic regions of the modern ocean. The character and magnitude of the biological response sustained by eddies are, however, variable. Here we present data from mesoscale eddies in the Sargasso Sea (Atlantic) and the waters off Hawai'i (Pacific), alongside mesoscale events that affected the Bermuda Atlantic Time Series (BATS) over the past decade. From this analysis, we suggest that the phytoplankton community structure sustained by mesoscale eddies is predetermined by the relative abundance of silicate over nitrate (Si*) in the upwelled waters. We present data that demonstrate that mode-water eddies (MWE) in the Sargasso Sea upwell locally formed waters with high Si* to the euphotic zone, and that cyclonic eddies in the Sargasso Sea introduce waters with low Si*, a signature that originated in the iron-limited Southern Ocean. We propose that this phenomenon can explain the observed abundance of large-diatom species in MWE and small prokaryotic phytoplankton in cyclonic features. In contrast to the Atlantic, cyclonic eddies in waters off Hawai'i induce North Pacific Intermediate Water (NPIW) that has high Si* and therefore also appears capable of establishing diatom populations. These observations suggest that the structure of phytoplankton communities sustained by eddies may not be directly related to the physical nature of the eddy but rather to the chemical composition of the upwelled waters. This paper links the biological production and export efficiency of mesoscale eddies to events in spatially and temporally disparate locations.

  5. Organic tracers of primary biological aerosol particles at subtropical Okinawa Island in the western North Pacific Rim

    NASA Astrophysics Data System (ADS)

    Zhu, Chunmao; Kawamura, Kimitaka; Kunwar, Bhagawati

    2015-06-01

    Primary biological aerosol particles (PBAPs) play an important role in affecting atmospheric physical and chemical properties. Aerosol samples were collected at Cape Hedo, Okinawa Island, Japan, from October 2009 to February 2012 and analyzed for five primary saccharides and four sugar alcohols as PBAP tracers. We detected high levels of sucrose in spring when blossoming of plants happens and prolifically emits pollen to the air. Concentrations of glucose, fructose, and trehalose showed levels higher than the other saccharides in spring in 2010. In comparison, primary saccharide levels were mutually comparable in spring, summer, and autumn in 2011, indicating the interannual variability of their local production in subtropical forests, which is driven by local temperature and radiation. High trehalose events were found to be associated with Asian dust outflows, indicating that Asian dust also contributes to PBAPs at Okinawa. Sugar alcohols peaked in summer and correlated with local precipitation and temperature, indicating high microbial activities. Positive matrix factorization analysis confirmed that the PBAPs are mainly derived from local vegetation, pollen, and fungal spores. A higher contribution of PBAP tracers to water-soluble organic carbon (WSOC) was found in summer (14.9%). The annual mean ambient loadings of fungal spores and PBAPs were estimated as 0.49 µg m-3 and 4.12 µg m-3, respectively, using the tracer method. We report, for the first time, year-round biomarkers of PBAP and soil dust and their contributions to WSOC in the subtropical outflow region of the Asian continent.

  6. Millennial scale oscillations in bulk δ15N and δ13C over the Mid- to Late Holocene seen in proteinaceous corals from the North Pacific Subtropical Gyre

    NASA Astrophysics Data System (ADS)

    Glynn, D. S.; Mccarthy, M. D.; McMahon, K.; Guilderson, T. P.

    2014-12-01

    The North Pacific Subtropical Gyre (NPSG) is the largest continuous ecosystem on this planet and is an important regulator of biogeochemical cycling and carbon sequestration. With evidence of its expansion in a warming climate, it is necessary to develop a more complete understanding of the variability in productivity and nutrient dynamics in this important ecosystem through time. We constructed a long-term, high resolution record of bulk record of stable nitrogen (δ15N) and carbon isotopes (δ13C) from multiple proteinaceous deep sea corals around Hawaii extending back ~5300 years with few gaps. Our data confirms the decreasing trend in δ15N since the Little Ice Age (1850s), which matches previously published results in part attributed to anthropogenic climate change (e.g. Sherwood et al. 2014). However, while the rate of change since the Little Ice Age (δ15N declines ~1‰ over ~150yrs) remains by far the most rapid throughout the longer record, there also appear to be longer-term (near-millennial scale) climatic oscillations of even greater magnitude (δ15N shifts ~1.5-2‰ over ~1000yrs). After removal of the Seuss Effect, δ13C values also declined ~1.5‰ since the Little Ice Age. Furthermore, there also appear to be oscillations in δ13C of ~1-2‰ over millennial timescales. These results reveal the existence of previously unrecognized long-term oscillations in NPSG biogeochemical cycles, which are likely linked to changes in phytoplankton species composition, food web dynamics, and/or variability in source nutrients and productivity possibly caused by changes in climate. This study provides insight into nutrient dynamics in the NPSG over the past five millennia, and offers a historical baseline to better analyze the effects of current anthropogenic climate forcing.

  7. Ocean noise in the tropical and subtropical Pacific Ocean.

    PubMed

    Sirović, Ana; Wiggins, Sean M; Oleson, Erin M

    2013-10-01

    Ocean ambient noise is well studied in the North Pacific and North Atlantic but is poorly described for most of the worlds' oceans. Calibrated passive acoustic recordings were collected during 2009-2010 at seven locations in the central and western tropical and subtropical Pacific. Monthly and hourly mean power spectra (15-1000 Hz) were calculated in addition to their skewness, kurtosis, and percentile distributions. Overall, ambient noise at these seven sites was 10-20 dB lower than reported recently for most other locations in the North Pacific. At frequencies <100 Hz, spectrum levels were equivalent to those predicted for remote or light shipping. Noise levels in the 40 Hz band were compared to the presence of nearby and distant ships as reported to the World Meteorological Organization Voluntary Observing Ship Scheme (VOS) project. There was a positive, but nonsignificant correlation between distant shipping and low frequency noise (at 40 Hz). There was a seasonal variation in ambient noise at frequencies >200 Hz with higher levels recorded in the winter than in the summer. Several species of baleen whales, humpback (Megaptera novaeangliae), blue (Balaenoptera musculus), and fin (B. physalus) whales, also contributed seasonally to ambient noise in characteristic frequency bands. PMID:24116406

  8. Ocean noise in the tropical and subtropical Pacific Ocean.

    PubMed

    Sirović, Ana; Wiggins, Sean M; Oleson, Erin M

    2013-10-01

    Ocean ambient noise is well studied in the North Pacific and North Atlantic but is poorly described for most of the worlds' oceans. Calibrated passive acoustic recordings were collected during 2009-2010 at seven locations in the central and western tropical and subtropical Pacific. Monthly and hourly mean power spectra (15-1000 Hz) were calculated in addition to their skewness, kurtosis, and percentile distributions. Overall, ambient noise at these seven sites was 10-20 dB lower than reported recently for most other locations in the North Pacific. At frequencies <100 Hz, spectrum levels were equivalent to those predicted for remote or light shipping. Noise levels in the 40 Hz band were compared to the presence of nearby and distant ships as reported to the World Meteorological Organization Voluntary Observing Ship Scheme (VOS) project. There was a positive, but nonsignificant correlation between distant shipping and low frequency noise (at 40 Hz). There was a seasonal variation in ambient noise at frequencies >200 Hz with higher levels recorded in the winter than in the summer. Several species of baleen whales, humpback (Megaptera novaeangliae), blue (Balaenoptera musculus), and fin (B. physalus) whales, also contributed seasonally to ambient noise in characteristic frequency bands.

  9. Microbial Group Specific Uptake Kinetics of Inorganic Phosphate and Adenosine-5′-Triphosphate (ATP) in the North Pacific Subtropical Gyre

    PubMed Central

    Björkman, Karin; Duhamel, Solange; Karl, David M.

    2012-01-01

    We investigated the concentration dependent uptake of inorganic phosphate (Pi) and adenosine-5′-triphosphate (ATP) in microbial populations in the North Pacific Subtropical Gyre (NPSG). We used radiotracers to measure substrate uptake into whole water communities, differentiated microbial size classes, and two flow sorted groups; Prochlorococcus (PRO) and non-pigmented bacteria (NPB). The Pi concentrations, uptake rates, and Pi pool turnover times (Tt) were (mean, ±SD); 54.9 ± 35.0 nmol L−1 (n = 22), 4.8 ± 1.9 nmol L−1 day−1 (n = 19), and 14.7 ± 10.2 days (n = 19), respectively. Pi uptake into >2 μm cells was on average 12 ± 7% (n = 15) of the total uptake. The kinetic response to Pi (10–500 nmol L−1) was small, indicating that the microorganisms were close to their maximum uptake velocity (Vmax). Vmax averaged 8.0 ± 3.6 nmol L−1 day−1 (n = 19) in the >0.2 μm group, with half saturation constants (Km) of 40 ± 28 nmol L−1 (n = 19). PRO had three times the cell specific Pi uptake rate of NPB, at ambient concentrations, but when adjusted to cells L−1 the rates were similar, and these two groups were equally competitive for Pi. The Tt of γ-P-ATP in the >0.2 μm group were shorter than for the Pi pool (4.4 ± 1.0 days; n = 6), but this difference diminished in the larger size classes. The kinetic response to ATP was large in the >0.2 μm class with Vmax exceeding the rates at ambient concentrations (mean 62 ± 27 times; n = 6) with a mean Vmax for γ-P-ATP of 2.8 ± 1.0 nmol L−1 day−1, and Km at 11.5 ± 5.4 nmol L−1 (n = 6). The NPB contribution to γ-P-ATP uptake was high (95 ± 3%, n = 4) at ambient concentrations but decreased to ∼50% at the highest ATP amendment. PRO had Km values 5–10 times greater than NPB. The above indicates that PRO and NPB were in close competition in terms of Pi acquisition

  10. Spatial and Temporal Variability in the Concentration and Turnover of the Inorganic Phosphate and Adenosine-5'-triphosphate pools in the North Pacific Subtropical Gyre

    NASA Astrophysics Data System (ADS)

    Björkman, Karin; Church, Matthew; Karl, David

    2015-04-01

    The microbial community's utilization of inorganic phosphate (Pi) and adenosine-5'-triphosphate (ATP) as a function of the Pi pool concentration was studied over a multi-year period at Station ALOHA (22.75˚N, 158˚W) in the North Pacific Subtropical Gyre (NPSG). Additionally, the spatial variability in these same properties was investigated along an east-west transect from California to Hawaii in the Fall of 2014. We used radiotracer techniques to determine the turnover times of the Pi or ATP pools respectively, and assessed the net production of dissolved organic phosphorus, and Pi hydrolysis rate from ATP. Pi concentrations in the upper water column at Station ALOHA are temporally highly dynamic, with periods of <10 nM-P to near 200 nM-P recorded within the top 50 m over the past decades of observations. During the California to Hawaii transect Pi concentrations showed a similarly large range (<10 to >200 nM-P), emphasizing the spatially and temporally mosaic nature of the upper ocean of this large biome. The Pi-pool turnover time ranged from a few hours to several weeks, and was strongly correlated with measured Pi pool concentrations (r2=0.8; n=30 Station ALOHA; n=15 transect). The calculated Pi uptake rates at Station ALOHA averaged 3.7±1.3 nM-P d-1 (n=30), reflecting the typically low maximum Pi uptake rates of the Prochlorococcus dominated community and the predominantly non-limiting Pi conditions. The Pi uptake rates along the transect were more variable than Station ALOHA (averaging 9.2±4.7 nM=P d-1, n=15), possibly due to a more diverse planktonic community structure, including stations with elevated concentrations of chlorophyll and primary productivity. The turnover time of the dissolved ATP pool was typically substantially shorter than for the Pi-pool (2-5 days at Station ALOHA; 0.3-2.5 days along the transect), likely reflecting its low nanomolar to picomolar ambient pool concentrations. However, at stations with the lowest SRP concentrations the

  11. Anomalous convective activity over sub-tropical east Pacific during 2015 and associated boreal summer monsoon teleconnections

    NASA Astrophysics Data System (ADS)

    Mujumdar, Milind; Sooraj, K. P.; Krishnan, R.; Preethi, B.; Joshi, Manish K.; Varikoden, Hamza; Singh, Bhupendra B.; Rajeevan, M.

    2016-08-01

    The eastern Pacific Ocean received a record highest number of sub-tropical convective activities during boreal summer (June-September) of 2015, since last four decades. The associated rainfall distribution was also atypical with anomalously enhanced rainfall extending from equator to sub-tropical central-eastern Pacific. The present analysis reveals a pronounced meridional sea surface temperature (SST) gradient across central-eastern Pacific, with the mean SST exceeding 28 °C over sub-tropical north Pacific, setting up favorable conditions for these enhanced convective activities. It is found that these anomalous features promoted northward spanning of westerly anomalies and drastically modified the east-west circulation over sub-tropical north Pacific. This seems to induce large-scale subsidence over the off-equatorial monsoon regions of south and south-east Asia, thus constituting an east-west asymmetry over sub-tropical Indo-Pacific region. Based on our observational study, it can be concluded that the sub-tropical convective activities over east Pacific may play a pivotal role in mediating the Pacific-monsoon teleconnection through the unexplored meridional SST gradient across Pacific.

  12. Heterotrophic prokaryote distribution along a 2300 km transect in the North Pacific subtropical gyre during a strong La Niña conditions: relationship between distribution and hydrological conditions

    NASA Astrophysics Data System (ADS)

    Girault, M.; Arakawa, H.; Barani, A.; Ceccaldi, H. J.; Hashihama, F.; Gregori, G.

    2015-06-01

    The spatial distribution of heterotrophic prokaryotes was investigated during the Tokyo-Palau cruise in the western part of the North Pacific subtropical gyre (NPSG) along a north-south transect between 33.60 and 13.25° N. The cruise was conducted in three different hydrological areas identified as the Kuroshio region, the subtropical gyre area and the transition zone. Two eddies were crossed along the transect: one cold-core cyclonic eddy and one warm-core anticyclonic eddy and distributions of the heterotrophic prokaryotes were recorded. By using analytical flow cytometry and a nucleic acid staining protocol, heterotrophic prokaryotes were discriminated into three subgroups depending on their nucleic acid content (low, high and very high nucleic acid contents labelled LNA, HNA and VHNA, respectively). Statistical analyses performed on the data set showed that LNA, mainly associated with low temperature and low salinity, were dominant in all the hydrological regions. In contrast, HNA distribution seemed to be associated with temperature, salinity, Chl a and silicic acid. A latitudinal increase in the HNA / LNA ratio was observed along the north-south transect and was related to higher phosphate and nitrate concentrations. However, the opposite relationship observed for the VHNA / HNA ratio suggested that the link between nucleic acid content and oligotrophic conditions is not linear, underlying the complexity of the biodiversity in the VHNA, HNA and LNA subgroups. In the Kuroshio Current, it is suggested that the high concentration of heterotrophic prokaryotes observed at station 4 was linked to the path of the cold cyclonic eddy core. In contrast, it is thought that low concentrations of heterotrophic prokaryotes in the warm core of the anticyclonic gyre (Sta. 9) are related to the low nutrient concentrations measured in the seawater column. Our results showed that the high variability between the various heterotrophic prokaryote cluster abundances depend both

  13. Long-range transport of the April 2001 dust clouds over the subtropical East Asia and the North Pacific and its impacts on ground-level air pollution: A Lagrangian simulation

    NASA Astrophysics Data System (ADS)

    Wang, Kuo-Ying

    2007-05-01

    One of the most remarkable Asian dust storms occurred in April 2001, during the periods of the Aerosol Characterization Experiment (ACE)-Asia and the Transport and Chemical Evolution Over the Pacific (TRACE-P) field experiments. Our high-resolution Lagrangian simulations and the detailed comparisons with the Total Ozone Mapping Spectrometer (TOMS)-Aerosol Index (AI) data, the Geostationary Meteorological Satellite (GMS)-5 derived dust distribution, and the ground-level ambient air particulate matter measurements over Taiwan in the subtropical East Asia reveal several features which were not reported before. We found that (1) the trans-Pacific long-range transport was dominated by the dust emissions from the natural source over the Gobi desert and the anthropogenic source over east China before 6-7 April, while the southward long-range transport to the subtropical East Asia were mainly contributed by the dust emissions from natural source over the Taklamakan and the Gobi, and the anthropogenic source over east China after 6-7 April; (2) the southward long-range transport implies that the anthropogenic pollution is ahead of the cold front (where the precipitation washes out the particulate matter), while the dust is behind the cold front. (3) The dust emissions from the Gobi during 7-9 April, anthropogenic emissions from east China during 9-10 April, and dust emissions from the Taklamakan during 1-4 April appear to have the most significant impacts on the ground-level particulate matter concentrations over Taiwan. The simulated particle emitted from desert regions before 6-7 April mainly confined to the Gobi and the Taklamakan regions until 6 April when they became highly mobile for the long-range transport by the large-scale cyclonic activity and its associated cold air outbreak. The southward transport characteristics simulated here are consistent with the aerosol characterization observed at Taiwan during this period. Our simulations reveal that the rapid trans-Pacific

  14. Nitrous oxide cycling in the water column and sediments of the oxygen minimum zone, eastern subtropical North Pacific, Southern California, and Northern Mexico (23°N-34°N)

    NASA Astrophysics Data System (ADS)

    Townsend-Small, Amy; Prokopenko, Maria G.; Berelson, William M.

    2014-05-01

    Identifying sources and sinks of N2O can illuminate N cycling processes in marine systems, particularly where changes in dissolved O2 can lead to changes in N cycling pathways (i.e., nitrification versus denitrification). We measured N2O and NO3- concentration and their stable isotope ratios (δ15N and δ18O) in the water column and sediments of the oxygen minimum zone in the nearshore eastern subtropical North Pacific (23°N-34°N). Atmospheric efflux of N2O ranged from 2.2 to 17.9 μmol m-2 d-1 or about 2-20 times higher than in oxygenated regions of the North Pacific. Surface waters were a source of 15N-depleted and 18O-enriched N2O to the atmosphere, indicating a bacterial, not archaeal, nitrification N2O source. Stable isotopes indicated that nitrification in both surface and intermediate waters (˜0-200 m) was the major source of N2O in this study area, with denitrification acting as a small N2O sink in strongly O2-depleted waters. Denitrification had a larger impact on observed patterns of N2O and NO3- concentrations and isotope ratios in the southern oxygen minimum zone. Sediments were generally neutral or a weak sink for N2O, with only one site (Soledad basin) showing a positive efflux of +3.5 ± 1.0 μmol N2O-N m-2 d-1. Sediment fluxes of N2O at all sites were several orders of magnitude smaller than fluxes of dinitrogen, nitrate, and ammonium measured in previous studies and did not appear to impact water column N2O concentrations. N2O was less than 0.1% of the N2 efflux from sedimentary denitrification.

  15. The North Pacific Gyre Mode

    NASA Astrophysics Data System (ADS)

    Schneider, N.; di Lorenzo, E.

    2007-12-01

    Discussion of North Pacific Decadal decadal variability has focused primarily on the Pacific Decadal Oscillation, the leading mode of sea surface temperature anomalies north of the tropics. The PDO appears to result from a superposition of SST pattern forced by the North Pacific atmosphere due to its intrinsic dynamics and teleconnected from the tropics, with a regional impact of the ocean circulation in the frontal regions associated with the Kuroshio/Oyashio and their extensions into the interior. Recent modeling, however, suggest that previously unexplained decadal changes of salinity, nutrient upwelling and chlorophyl in the California Current are not dominated by the PDO. Rather, these are associated with a mode of variability associated with wind driven changes of the North Pacific Gyre. Consideration of this mode variability may thus be important to understand present and future variations of the North Pacific ecosystem, and in the interpretation of climate proxies.

  16. Late Holocene Plankton Domain Shifts in the North Pacific Subtropical Gyre Revealed by Amino Acid Specific δ13C and δ15N Records from Proteinaceous Deep-Sea Corals

    NASA Astrophysics Data System (ADS)

    Sherwood, O.; McMahon, K.; Guilderson, T. P.; Mccarthy, M. D.

    2014-12-01

    Recent observations from station ALOHA have framed a new paradigm about the dynamic nature of subtropical ocean gyres. These vast regions are now known to vary physically and biologically, over a range of timescales, with important implications for the export of carbon to the deep ocean. In the largest of these gyres, the North Pacific subtropical gyre (NPSG), primary production has increased in recent decades despite a reduction in nutrient supply to surface waters. This is thought to be the result of a shift in plankton community structure from mostly eukaryotes to mostly dinitrogen-fixing prokaryotes. It remains uncertain, however, whether the recent plankton community domain shift can be linked to cyclical climate variability or a long-term global warming trend. To establish historical trends, we analyzed nitrogen (δ15N) and carbon (δ13C) isotopic records preserved in the skeletons of extraordinarily long-lived, proteinaceous deep-sea corals, which feed on, and therefore serve as a proxy for, exported productivity. Specimens of Hawaiian gold coral (Kulamanamana haumeaae) were collected from the Hawaiian archipelago and sampled across the skeletal growth rings to generate high-resolution (5 yr), millennial-length records of "bulk" δ15N and δ13C. After a millennium of relatively minor fluctuation, δ15N decreased by up to 2 per mil between 1850 and the present. Analysis of amino-acid-specific δ15N on a subset of the samples, combined with isotopic mass balance between nitrate and nitrogen fixation, implied a 17 to 27 % increase in nitrogen fixation as the underlying cause for the observed trends. This interpretation is supported by analysis of the δ13C of essential amino acids, which serve as isotopic fingerprints of primary producer origin. Together, these independent lines of evidence describe a domain shift from a dominantly eukaryotic to dinitrogen-fixing prokaryotic plankton community. This shift has been ongoing since the end of the Little Ice Age

  17. Measurement of dark, particle-generated superoxide and hydrogen peroxide production and decay in the subtropical and temperate North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Roe, Kelly L.; Schneider, Robin J.; Hansel, Colleen M.; Voelker, Bettina M.

    2016-01-01

    chemiluminescence detection, using dark incubations of unfiltered water samples to simultaneously determine production and decay rates. H2O2 concentrations at Station ALOHA ranged from 7 to 88 nM. Dark production rates and decay rate coefficients were low (mostly <1.5 nM hr-1 and <0.03 h-1, respectively); higher values were detected when biota were pre-concentrated with net tows. These rates of ROS production are lower than those reported by previous studies in other regions of the Pacific Ocean, but could still be significant compared to photochemical production.

  18. Changes in fecal pellet characteristics with depth as indicators of zooplankton repackaging of particles in the mesopelagic zone of the subtropical and subarctic North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Wilson, Stephanie E.; Steinberg, Deborah K.; Buesseler, Ken O.

    2008-07-01

    We investigated how fecal pellet characteristics change with depth in order to quantify the extent of particle repackaging by mesopelagic zooplankton in two contrasting open-ocean systems. Material from neutrally buoyant sediment traps deployed in the summer of 2004 and 2005 at 150, 300, and 500 m was analyzed from both a mesotrophic (Japanese time-series station K2) and an oligotrophic (Hawaii Ocean Time series—HOT station ALOHA) environment in the Pacific Ocean as part of the VERtical Transport In the Global Ocean (VERTIGO) project. We quantified changes in the flux, size, shape, and color of particles recognizable as zooplankton fecal pellets to determine how these parameters varied with depth and location. Flux of K2 fecal pellet particulate organic carbon (POC) at 150 and 300 m was four to five times higher than at ALOHA, and at all depths, fecal pellets were two to five times larger at K2, reflective of the disparate zooplankton community structure at the two sites. At K2, the proportion of POC flux that consisted of fecal pellets generally decreased with depth from 20% at 150 m to 5% at 500 m, whereas at ALOHA this proportion increased with depth (and was more variable) from 14% to 35%. This difference in the fecal fraction of POC with increasing depth is hypothesized to be due to differences in the extent of zooplankton-mediated fragmentation (coprohexy) and in zooplankton community structure between the two locations. Both regions provided indications of sinking particle repackaging and zooplankton carnivory in the mesopelagic. At ALOHA, this was reflected in a significant increase in the mean flux of larvacean fecal pellets from 150 to 500 m of 3-46 μg C m -2 d -1, respectively, and at K2 a large peak in larvacean mean pellet flux at 300 m of 3.1 mg C m -2 d -1. Peaks in red pellets produced by carnivores occurred at 300 m at K2, and a variety of other fecal pellet classes showed significant changes in their distribution with depth. There was also

  19. Causes of Decadal Climate Variability over the North Pacific and North America.

    PubMed

    Latif, M; Barnett, T P

    1994-10-28

    The cause of decadal climate variability over the North Pacific Ocean and North America is investigated by the analysis of data from a multidecadal integration with a state-of-the-art coupled ocean-atmosphere model and observations. About one-third of the low-frequency climate variability in the region of interest can be attributed to a cycle involving unstable air-sea interactions between the subtropical gyre circulation in the North Pacific and the Aleutian low-pressure system. The existence of this cycle provides a basis for long-range climate forecasting over the western United States at decadal time scales. PMID:17793457

  20. Causes of decadal climate variability over the North Pacific and North America

    SciTech Connect

    Latif, M. ); Barnett, T.P. )

    1994-10-28

    The cause of decadal climate variability over the North Pacific Ocean and North America is investigated by the analysis of data from a multidecadal integration with a state-of-the-art coupled ocean-atmosphere model and observations. About one-third of the low-frequency climate variability in the region of interest can be attributed to a cycle involving unstable air-sea interactions between the subtropical gyre circulation in the North Pacific and the Aleutian low-pressure system. The existence of this cycle provides a basis for long-range climate forecasting over the western United States at decadal time scales. 17 refs., 5 figs.

  1. Role of horizontal density advection in seasonal deepening of the mixed layer in the subtropical Southeast Pacific

    NASA Astrophysics Data System (ADS)

    Liu, Qinyu; Lu, Yiqun

    2016-04-01

    The mechanisms behind the seasonal deepening of the mixed layer (ML) in the subtropical Southeast Pacific were investigated using the monthly Argo data from 2004 to 2012. The region with a deep ML (more than 175 m) was found in the region of (22°-30°S, 105°-90°W), reaching its maximum depth (~200 m) near (27°-28°S, 100°W) in September. The relative importance of horizontal density advection in determining the maximum ML location is discussed qualitatively. Downward Ekman pumping is key to determining the eastern boundary of the deep ML region. In addition, zonal density advection by the subtropical countercurrent (STCC) in the subtropical Southwest Pacific determines its western boundary, by carrying lighter water to strengthen the stratification and form a "shallow tongue" of ML depth to block the westward extension of the deep ML in the STCC region. The temperature advection by the STCC is the main source for large heat loss from the subtropical Southwest Pacific. Finally, the combined effect of net surface heat flux and meridional density advection by the subtropical gyre determines the northern and southern boundaries of the deep ML region: the ocean heat loss at the surface gradually increases from 22?S to 35?S, while the meridional density advection by the subtropical gyre strengthens the stratification south of the maximum ML depth and weakens the stratification to the north. The freshwater flux contribution to deepening the ML during austral winter is limited. The results are useful for understanding the role of ocean dynamics in the ML formation in the subtropical Southeast Pacific.

  2. Paleoceanography/climate and taphonomy at intermediate water depth in the Subtropical Western North Pacific Ocean over the last 1 Ma from IODP Exp 350 Sites U1436C and U1437B, Izu arc area.

    NASA Astrophysics Data System (ADS)

    Vautravers, Maryline

    2015-04-01

    IODP Expedition 350 Site U1436C lies in the western part of the Izu fore arc basin, ~60 km east of the arc front volcano Aogashima, at 1776 m water depth. This site is a technical hole (only a 150 m long record) for a potential future deep drilling by Chikyu. Site U1437 is located in the Izu rear arc, ~90 km west of the arc front volcanoes Myojinsho and Myojin Knoll, at 2117 m water depth. At this site in order to study the evolution of the IZU rear arc crust we recovered a 1800 meter long sequence of mud and volcaniclastic sediments. These sites provide a rich and well-preserved record of volcanic eruptions within the area of the Izu Bonin-Arc. However, the material recovered, mostly mud with ash containing generally abundant planktonic foraminifera, can support additional paleoceanographic goals in an area affected by the Kuroshio Current. Also, the hydrographic divide created by the Izu rise provides a rare opportunity to gain some insight into the operation of the global intermediate circulation. The Antarctic Intermediate Water Mass is more influential at the depth of U1437B in the West and the North Pacific Intermediate Water at Site U1436C to the East. We analyzed 460 samples recovered at Sites U1436C and U1437B for a quantitative planktonic foraminifer study, and also for carbonate preservation indices, including: shell weight, percent planktonic foraminifera fragments planktonic foraminifer concentrations, various faunal proxies, and benthic/planktonic ratio. We measured the stable isotopes for a similar number of samples using the thermocline dwelling Neogloboquadrina dutertrei. The dataset presented here covers the last 1 Ma at Site U1437B and 0.9 Ma at Site U1436C. The age models for the two sites are largely established through stable isotope stratigraphy (this study). On their respective age models we evidence based on polar/subpolar versus subtropical faunal assemblages changes qualitative surface water temperature variations recording the changing

  3. Thousand Year Archives of the Bulk and Compound-Specific δ15N of Export Production From the North Pacific Subtropical Gyre Indicate Increasing Nitrogen Fixation Over the Past 150 Years

    NASA Astrophysics Data System (ADS)

    Sherwood, O.; Batista, F. C.; Brown, J. T.; Guilderson, T. P.; McCarthy, M.

    2012-12-01

    Stable nitrogen isotopic analysis of amino acids (δ15N-AA) preserved in proteins has emerged as a powerful new tool to explore trophic levels and nutrient cycling in nature. To date, little has been done to explore δ15N-AA in paleo-studies of the marine nitrogen cycle. We analysed the bulk and AA-specific δ15N in the long-lived, deep-sea, proteinaceous coral Gerardia. By feeding on sinking particulate organic matter, proteinaceous corals integrate the biogeochemical signature of recently exported production within discrete skeletal growth layers. Sub-decadal resolution time-series records spanning the time period 1000 AD to present were generated from specimens of Gerardia collected from the main Hawaiian Islands, Cross Seamount, and French Frigate Shoals in the North Pacific Subtropical Gyre (NPSG). Records of bulk δ15N from the three different locations, geographically separated by up to 1000 km, showed remarkably similar long term trends. Bulk δ15N remained relatively stable from ~1000-1850 years AD, and then decreased by a total of 2 ‰ from ~1850 AD to the present. The δ15N-AA of the "trophic" group of amino acids indicated no significant changes in trophic level or microbial re-synthesis of export production over this time period. The δ15N of "source" amino acids was significantly correlated with corresponding values of bulk δ15N, with the δ15N of phenylalanine decreasing from 4.2 to 2.1‰. The latter value is similar to recent measurements of subsurface nitrate δ15N near Hawaii, suggesting that the δ15N of phenylalanine may be used to quantitatively track changes in the isotopic signature of nitrate at the base of the food web. Using a simple isotopic mass balance between upwelled nitrate and nitrogen fixation we calculate a 30% increase in nitrogen fixation in the NPSG since ~1850. These results provide invaluable long-term context for recent observations, and highlight profound changes in the marine biogeochemical cycling of nitrogen over the

  4. Covariability of western tropical Pacific-North Pacific atmospheric circulation during summer

    PubMed Central

    Yun, Kyung-Sook; Yeh, Sang-Wook; Ha, Kyung-Ja

    2015-01-01

    North Pacific subtropical high (NPSH) is permanent high-pressure system over the Northern Pacific Ocean and it extends to the western North Pacific during the boreal summer (June-July-August), which is so called the western North Pacific subtropical high (WNPSH). Here, we examine the covariability of the NPSH-WNPSH during summer using both observation and Coupled Model Intercomparison Project phase 5 (CMIP5) model data. The statistical analyses indicate that the NPSH-WNPSH covariability shows significant decadal variability in the observations, in addition, the in-phase relationship of NPSH-WNPSH is enhanced after the mid-to-late 1990s. A dipole-like sea surface temperature (SST) pattern, i.e., a warming in the western Pacific and a cooling in the eastern Pacific, is dominant after the mid-to-late 1990s, which acts to enhance the covariability of NPSH-WNPSH by modulating the atmospheric teleconnections. However, the covariability of NPSH-WNPSH in the future climate is not much influenced by the anthropogenic forcing but it is largely characterized by the natural decadal-to-interdecadal variability, implying that the enhancement of NPSH-WNPSH covariability after the mid-to-late 1990s could be considered as part of decadal-to-interdecadal variability. PMID:26594044

  5. Formation Mechanism of Barrier Layer in the Subtropical Pacific

    NASA Astrophysics Data System (ADS)

    Katsura, S.; Oka, E.; Sato, K.

    2014-12-01

    Formation mechanism of barrier layers (BLs) in the subtropical Pacific was investigated by using Argo profiling float data and shipboard hydrographic section data. In this region, BLs were formed mainly in winter in association with the sea surface salinity (SSS) front, which was located on the equator side of the SSS maximum region. While BLs from gridded Argo data were broadly distributed, their distribution from raw Argo profiles was patchy and their temporal scale was shorter than 10 days. Formation mechanism of BLs was attributed to two processes: freshening near the sea surface and salinification in the subsurface. As for the former process, poleward Ekman advection of fresher water from the tropics across the SSS front was dominant, while the effect of precipitation was small. As for the latter process, inflow of high salinity water into mixed layers associated with the SSS front can contribute to the BL formation, but actually the core of subducted Tropical Water was too deep to affect salinity structure in the mixed layers across the seasonal thermocline. These features strongly suggest that tilting of the SSS front is essentially important for the BL formation in the subtropical Pacific. This tilting process can only occur where the contribution of horizontal SSS gradient to the horizontal density gradient is strong, and explains why spatial distribution of BLs corresponded to the SSS front. Seasonal variation of BLs corresponded well to that of mixed layer depth, indicating that the deeper mixed layers are before the BL formation, the thicker BLs are formed when the SSS front is tilted.

  6. Decadal climate variability over the North Pacific and North America: Dynamics and predictability

    SciTech Connect

    Latif, M.; Barnett, T.P.

    1996-10-01

    The dynamics and predictability of decadal climate variability over the North Pacific and North America are investigated by analyzing various observation datasets and the output of a state of the art coupled ocean-atmosphere general circulation model that was integrated for 125 years. Both the observations and model results support the picture that the decadal variability in the regional of interest is based on a cycle involving unstable ocean-atmosphere interactions over the North Pacific. The period of this cycle is of the order of a few decades. The cycle involves the two major circulation regimes in the North Pacific climate system, the subtropical ocean gyre, and the Aleutian low. 41 refs., 18 figs.

  7. North Pacific High: an hypothesis

    NASA Astrophysics Data System (ADS)

    Kenyon, Kern E.

    An hypothesis is offered for the cause and maintenance of the North Pacific High (NPH). Over a broad but well defined open ocean area, in the mid-latitude North Pacific, the ocean heats the atmosphere from below, and outside the boundaries of the heat source the ocean cools the air at the sea surface. Vertical thermal convection in the air over the heat source brings down relatively cool dry air, producing a horizontal contrast mainly in relative humidity inside and outside the heat source region. Consequently relatively high density air is produced over the heat source, and if the temperature is approximately constant, then the barometric pressure will be high over the heat source as well. Being unstable, due to a horizontal pressure gradient, the high density air will try to move radially outward from the heat source, and the Coriolis force will bend the outward flow into a clockwise circulation around the center of high pressure. The heat source is provided by a broad northeastward warm surface current, previously described, that crosses mid-latitudes on the eastern side of the North Pacific at all times of the year. Given the known characteristics of the warm current, the heat source mechanism can explain the observed seasonal variations of the NPH also. A more complete substantiation (or refutation) of the general hypothesis for the origin of the NPH must await the accumulation of additional oceanic and atmospheric data.

  8. Eastern tropical north Pacific coral radiocarbon reveals North Pacific Gyre Oscillation variability

    NASA Astrophysics Data System (ADS)

    Rafter, P. A.; Ferguson, J. E.; Sanchez, S. C.; Druffel, E. R. M.; Southon, J. R.; Graven, H. D.; Carriquiry, J. D.

    2015-12-01

    The North Pacific Oscillation (NPO) is possibly a major influence on global climate through its influence on the El Niño-Southern Oscillation (ENSO), but the decadal-scale cyclicity and limited observations (≈50 years) of the NPO make it difficult to explore this relationship. One approach to this problem is to use marine archives (e.g., corals and sediments) to build significantly longer records of the oceanic expression of the NPO—the North Pacific Gyre Oscillation (NPGO). For example, the strengthened winds associated with positive NPO sea level pressure distributions increase gyre circulation, increasing upwelling in the coastal northeastern Pacific and equatorward flow of the California Current. However, marine archives along the coast are potentially influenced by both NPGO and ENSO and are not ideal. Here we demonstrate that corals from the Revillagigedo Islands—in the Eastern Tropical North Pacific (ETNP)—provide a relatively "clean" record of NPGO variability. In particular, coral Δ14C and δ18O show fluctuations between salty / Δ14C "young" waters (native to the ETNP) and fresh / Δ14C "old" waters (similar to those upwelled off the California margin). This variability is highly coherent and consistent with the NPGO index, such that positive NPGO (and therefore NPO) corresponds to a increased presence of California Current waters in the ETNP. ENSO appears to have little influence on this record, probably because of minimal change in seawater Δ14C associated with the poleward propagating Kelvin waves associated with ENSO. Pre-instrumental records of NPGO, like these from the Revillagigedo Island corals, are necessary to begin understanding the tropical-subtropical drivers of NPO, ENSO, and other ocean-atmosphere climate phenomena.

  9. Plastic pollution in the South Pacific subtropical gyre.

    PubMed

    Eriksen, Marcus; Maximenko, Nikolai; Thiel, Martin; Cummins, Anna; Lattin, Gwen; Wilson, Stiv; Hafner, Jan; Zellers, Ann; Rifman, Samuel

    2013-03-15

    Plastic marine pollution in the open ocean of the southern hemisphere is largely undocumented. Here, we report the result of a (4489 km) 2424 nautical mile transect through the South Pacific subtropical gyre, carried out in March-April 2011. Neuston samples were collected at 48 sites, averaging 50 nautical miles apart, using a manta trawl lined with a 333 μm mesh. The transect bisected a predicted accumulation zone associated with the convergence of surface currents, driven by local winds. The results show an increase in surface abundance of plastic pollution as we neared the center and decrease as we moved away, verifying the presence of a garbage patch. The average abundance and mass was 26,898 particles km(-2) and 70.96 g km(-2), respectively. 88.8% of the plastic pollution was found in the middle third of the samples with the highest value of 396,342 particles km(-2) occurring near the center of the predicted accumulation zone. PMID:23324543

  10. Plastic pollution in the South Pacific subtropical gyre.

    PubMed

    Eriksen, Marcus; Maximenko, Nikolai; Thiel, Martin; Cummins, Anna; Lattin, Gwen; Wilson, Stiv; Hafner, Jan; Zellers, Ann; Rifman, Samuel

    2013-03-15

    Plastic marine pollution in the open ocean of the southern hemisphere is largely undocumented. Here, we report the result of a (4489 km) 2424 nautical mile transect through the South Pacific subtropical gyre, carried out in March-April 2011. Neuston samples were collected at 48 sites, averaging 50 nautical miles apart, using a manta trawl lined with a 333 μm mesh. The transect bisected a predicted accumulation zone associated with the convergence of surface currents, driven by local winds. The results show an increase in surface abundance of plastic pollution as we neared the center and decrease as we moved away, verifying the presence of a garbage patch. The average abundance and mass was 26,898 particles km(-2) and 70.96 g km(-2), respectively. 88.8% of the plastic pollution was found in the middle third of the samples with the highest value of 396,342 particles km(-2) occurring near the center of the predicted accumulation zone.

  11. Decadal variability in the abundance of Pacific saury and its response to climatic/oceanic regime shifts in the northwestern subtropical Pacific during the last half century

    NASA Astrophysics Data System (ADS)

    Tian, Yongjun; Ueno, Yasuhiro; Suda, Maki; Akamine, Taturo

    2004-12-01

    Pacific saury ( Cololabis saira) is one of the most important, small-sized, pelagic fishes in the North Pacific. Using correlation analysis and principal component analysis (PCA), we examined the relationships between climatic/oceanographic indices (Asian monsoon index (MOI), Southern Oscillation Index (SOI), North Pacific Index (NPI), Arctic Oscillation Index (AOI), Pacific Decadal Oscillation (PDO) index, air temperature, wind velocity, sea surface temperature (SST), and surface current velocity (SCV) in the Kuroshio axis), and abundance/biological indices of Pacific saury (adult catch, catch per unit effort, i.e., CPUE, condition factor, and body length and larval density) in order to detect the response of Pacific saury abundance to the recent climatic/oceanic regime shifts (1976/1977, 1987/1988, and 1997/1998). Our oceanographic analyses show that notable regime shifts occurred in 1987/1988 and possibly 1997/1998 in the Kuroshio region, while the same kind of regime shift was not readily apparent there in 1976/1977. Results of our oceanographic/biological analyses show that the decadal-scale variation pattern in Pacific saury abundance responded well to the regime shifts of 1987/1988 and 1997/1998. These results indicate that only the regime shifts which occurred in the Kuroshio region can affect Pacific saury abundance. Our results also showed that the abundance and biological indices of saury significantly correlated with both the SSTs in the northwestern Kuroshio waters and the SCV in the Kuroshio axis in winter. These correlations suggest that winter oceanographic conditions in the Kuroshio region strongly affect the early survival process and determine the recruitment success of Pacific saury. The abundance of other major small pelagic species also changed greatly around 1989, suggesting that the regime shift in the late 1980s occurred in the pelagic ecosystem basin. We concluded that Pacific saury could be used as a bio-indicator of regime shifts in the

  12. Southward spreading of the Fukushima-derived radiocesium across the Kuroshio Extension in the North Pacific

    NASA Astrophysics Data System (ADS)

    Kumamoto, Yuichiro; Aoyama, Michio; Hamajima, Yasunori; Aono, Tatsuo; Kouketsu, Shinya; Murata, Akihiko; Kawano, Takeshi

    2014-03-01

    The accident of the Fukushima Dai-ichi nuclear power plant in March 2011 released a large amount of radiocesium into the North Pacific Ocean. Vertical distributions of Fukushima-derived radiocesium were measured at stations along the 149°E meridian in the western North Pacific during the winter of 2012. In the subtropical region, to the south of the Kuroshio Extension, we found a subsurface radiocesium maximum at a depth of about 300 m. It is concluded that atmospheric-deposited radiocesium south of the Kuroshio Extension just after the accident had been transported not only eastward along with surface currents but also southward due to formation/subduction of subtropical mode waters within about 10 months after the accident. The total amount of decay-corrected 134Cs in the mode water was an estimated about 6 PBq corresponding to 10-60% of the total inventory of Fukushima-derived 134Cs in the North Pacific Ocean.

  13. The role of the cold Okhotsk Sea in the strengthening the Pacific subtropical high and Baiu precipitation

    NASA Astrophysics Data System (ADS)

    Kawasaki, Kenta; Tachibana, Yoshihiro; Nakamura, Tetsu; Yamazaki, Koji; Kodera, Kunihiko

    2016-04-01

    It is commonly known that the formation of a stationery precipitation zone in association with the Baiu front is influenced by the existence of the warm Tibetan Plateau. Some GCM studies in which the Tibetan Plateau is removed pointed out that without the Tibetan Plateau, the Baiu front wound not appear. The cold Okhotsk Sea, which is located to the north of Japan, is also important in forming cold air for the Bai front. This study focused on the role of the Okhotsk Sea in the formation of the Baiu front by using an atmospheric GCM. One GCM is executed without the Okhotsk Sea, in which was changed to an eastern part of the Eurasian continent as if the Okhotsk Sea was totally landfilled (land run). The other (sea run) is a control run under the boundary condition of climatic seasonal changes of the SST over the globe. The comparison of the land run with the sea run showed that precipitation over Japan would weaken in the Baiu season without the Okhotsk Sea, indicating that the existence of the Okhotsk Sea has an impact on the increase in precipitation. The precipitation increase in the sea run is directly accounted by the strengthening of southeast wind in association with the strengthening of the subtropical high located over the Pacific Ocean. The westerly jet, which is located at the northern part of the subtropical high, was also accelerated in the sea run. The subtropical high in association with the accelerated jet was strengthened by meridional atmospheric thermal gradient caused by underlying cold Okhotsk Sea and the warm Pacific Ocean. The strengthened thermal gradient also activated the storm track that extends zonally over the Okhotsk Sea, and the activated storm track further strengthened the jet and subtropical high by wave-mean flow feedback. This feedback loop could further strengthen the Baiu precipitation. In consequence, the Okhotsk plays a significant role in the strengthening the subtropical high and its associated Baiu precipitation.

  14. Heat and salt transport throughout the North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Yang, Lina; Yuan, Dongliang

    2016-11-01

    Absolute geostrophic currents in the North Pacific Ocean are calculated using the P-vector method and gridded Argo profiling data from January 2004 to December 2012. Three-dimensional structures and seasonal variability of meridional heat transport (MHT) and meridional salt transport (MST) are analyzed. The results show that geostrophic and Ekman components are generally opposite in sign, with the southward geostrophic component dominating in the subtropics and the northward Ekman component dominating in the tropics. In combination with the net surface heat flux and the MST through the Bering Strait, the MHT and MST of the western boundary currents (WBCs) are estimated for the first time. The results suggest that the WBCs are of great importance in maintaining the heat and salt balance of the North Pacific. The total interior MHT and MST in the tropics show nearly the same seasonal variability as that of the Ekman components, consistent with the variability of zonal wind stress. The geostrophic MHT in the tropics is mainly concentrated in the upper layers, while MST with large amplitude and annual variation can extend much deeper. This suggests that shallow processes dominate MHT in the North Pacific, while MST can be affected by deep ocean circulation. In the extratropical ocean, both MHT and MST are weak. However, there is relatively large and irregular seasonal variability of geostrophic MST, suggesting the importance of the geostrophic circulation in the MST of that area.

  15. Heat and salt transport throughout the North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Yang, Lina; Yuan, Dongliang

    2016-03-01

    Absolute geostrophic currents in the North Pacific Ocean are calculated using the P-vector method and gridded Argo profiling data from January 2004 to December 2012. Three-dimensional structures and seasonal variability of meridional heat transport (MHT) and meridional salt transport (MST) are analyzed. The results show that geostrophic and Ekman components are generally opposite in sign, with the southward geostrophic component dominating in the subtropics and the northward Ekman component dominating in the tropics. In combination with the net surface heat flux and the MST through the Bering Strait, the MHT and MST of the western boundary currents (WBCs) are estimated for the first time. The results suggest that the WBCs are of great importance in maintaining the heat and salt balance of the North Pacific. The total interior MHT and MST in the tropics show nearly the same seasonal variability as that of the Ekman components, consistent with the variability of zonal wind stress. The geostrophic MHT in the tropics is mainly concentrated in the upper layers, while MST with large amplitude and annual variation can extend much deeper. This suggests that shallow processes dominate MHT in the North Pacific, while MST can be affected by deep ocean circulation. In the extratropical ocean, both MHT and MST are weak. However, there is relatively large and irregular seasonal variability of geostrophic MST, suggesting the importance of the geostrophic circulation in the MST of that area.

  16. Two centuries of coherent decadal climate variability across the Pacific North American region

    NASA Astrophysics Data System (ADS)

    Sanchez, S. C.; Charles, C. D.; Carriquiry, J. D.; Villaescusa, J. A.

    2016-09-01

    The decadal variability of the Pacific Ocean and North American hydroclimate are subjects of immediate concern for society, yet the length of the instrumental record limits full mechanistic understanding of this variability. Here we introduce a 178 year, seasonally resolved coral oxygen isotopic record from Clarion Island (18°N, 115°W), a sampling a subtropical region that is strongly influenced by the decadal-scale fluctuations of the North Pacific Gyre Oscillation and a region that serves as a critical locus for the communication of climate anomalies with the tropics. This Mexican Pacific coral record is highly correlated to coral records from the central tropical Pacific and tree ring records from western North America. Significant changes in the amplitude of oceanic decadal variability in the early nineteenth century are mirrored in the drought reconstructions in western North America. The spatial manifestation of this relationship was relatively invariant, despite notable changes in the climatic mean state.

  17. Plastic Accumulation in the North Atlantic Subtropical Gyre

    NASA Astrophysics Data System (ADS)

    Law, Kara Lavender; Morét-Ferguson, Skye; Maximenko, Nikolai A.; Proskurowski, Giora; Peacock, Emily E.; Hafner, Jan; Reddy, Christopher M.

    2010-09-01

    Plastic marine pollution is a major environmental concern, yet a quantitative description of the scope of this problem in the open ocean is lacking. Here, we present a time series of plastic content at the surface of the western North Atlantic Ocean and Caribbean Sea from 1986 to 2008. More than 60% of 6136 surface plankton net tows collected buoyant plastic pieces, typically millimeters in size. The highest concentration of plastic debris was observed in subtropical latitudes and associated with the observed large-scale convergence in surface currents predicted by Ekman dynamics. Despite a rapid increase in plastic production and disposal during this time period, no trend in plastic concentration was observed in the region of highest accumulation.

  18. Number-size distribution of aerosol particles and new particle formation events in tropical and subtropical Pacific Oceans

    NASA Astrophysics Data System (ADS)

    Ueda, S.; Miura, K.; Kawata, R.; Furutani, H.; Uematsu, M.; Omori, Y.; Tanimoto, H.

    2016-10-01

    Number-size distributions of aerosol particles with diameters of 10-500 nm in the marine boundary layer were observed continually onboard the R/V Hakuho Maru over the equatorial and subtropical North Pacific and South Pacific during December 2011-March 2012. Number-size distributions over each area were parameterized using a sum of up to three lognormal functions. Bi-modal size distributions with peak diameters at 30-80 nm (Aitken mode) and 100-200 nm (accumulation mode) were observed frequently. Larger peak diameters of Aitken and accumulation modes were observed over the eastern equator, where 5-day backward trajectories showed that the air masses had derived from high-chlorophyll oceanic regions without precipitation. Smaller peak diameters and low concentrations were often observed over the North Pacific. The trajectories show that such air mass originated from oceanic regions with less chlorophyll, exhibiting high precipitation frequency. New particle formation (NPF) events have often been observed over the mid-latitude eastern South Pacific with a low condensation sink (CS) and some dimethyl sulfide, although none was observed over the equator, where CS was higher. The lesser CS condition at NPF events was mostly correlated with local precipitation or precipitation along the trajectories within 1 day. These results suggest that differences of the number-size distribution and occasions of NPF events among sea areas most closely accord with precipitation along the trajectories.

  19. Possible relationship between East Asian summer monsoon and western North Pacific tropical cyclone genesis frequency

    NASA Astrophysics Data System (ADS)

    Choi, Ki-Seon; Cha, Yumi; Kim, Hae-Dong; Kang, Sung-Dae

    2016-04-01

    In the present study, the fact that strong positive correlations have existed between East Asian summer monsoons (EASMs) and western North Pacific tropical cyclone (TC) genesis frequency over the last 37 years was found. To figure out the cause of these correlations, 7 years (positive East Asian summer monsoon index (EASMI) phase) that have the highest values and 7 years (negative EASMI phase) that have the lowest values in the normalized EASM index were selected and the differences in averages between the two phases were analyzed. In the positive EASMI phase, TCs mainly occurred in the northwestern waters of the tropical and subtropical western North Pacific and showed a tendency to move from the far eastern waters of the Philippines, pass the East China Sea, and move northward toward Korea and Japan. On the 500 hPa streamline, whereas anomalous anticyclones developed in the East Asia middle-latitude region, anomalous cyclones developed in the tropical and subtropical western North Pacific. Therefore, in this phase, whereas EASMs were weakened, western North Pacific summer monsoons (WNPSMs) were strengthened so that some more TCs could occur. In addition, in the case of the East China Sea and the southern waters of Japan located between the two anomalous pressure systems, TCs could move some more toward the East Asia middle-latitude region in this phase. According to an analysis of the 850 hPa relative vorticity, negative anomalies were strengthened in the East Asia middle-latitude region while positive anomalies were strengthened in the region south to 25 N. Therefore, in the positive EASMI phase, whereas EASMs were weakened, WNPSMs were strengthened so that some more TCs could occur. According to an analysis of the 850 and 200 hPa horizontal divergence, whereas anomalous downward flows were strengthened in the East Asia middle-latitude region, anomalous upward flows were strengthened in the tropical and subtropical western North Pacific. According to an analysis

  20. Two different deglaciation processes in the subtropical Pacific at MIS 5/6 and 1/2

    NASA Astrophysics Data System (ADS)

    Ujiie, Y.; Asahi, H.

    2011-12-01

    Deglaciation process is one of the results that the tropical climate forcing impact on the global changes by its large heat capacity. However, the deglacial fluctuation has poorly been explored in the tropical Pacific area due to less resolution records from the marine deposits. The Okinawa region is available to represent the high-resolution paleocenographic records of the tropical-subtropical Pacific during the late Quaternary, because of the oscillation between the Kuroshio Current continuing from the North Equatorial Current and central water of the subtropical gyre in this region. Two IMAGES cores were collected from the Okinawa Trough (under the Kuroshio Current) and Ryukyu Trench (under the central water of the subtropical gyre), respectively. Both cores MD982196 (Okinawa Trough) and MD012398 (Ryukyu Trench) covered over the records until Marine Isotope Stage (MIS) 7. Here, we aim to demonstrate the deglacial fluctuations of the surface and intermediate waters during two glacial-interglacial shifts, MIS 6 to 5 and MIS 2 to 1, based on the comprehensive analyses of the oxygen isotopes, Mg/Ca ratios of two planktic foraminiferal faunas (surface and upper intermediate species), and faunal assemblages of planktic foraminifera. The glacial-interglacial cycles were clearly confirmed in whole of the Okinawa region by the planktic δ18O curves. Surface Mg/Ca paleo-temperature showed a same trend as the δ18O curve. However, the paleo-temperature of the upper intermediate water showed unique fluctuation: temperature increased from late MIS 6 to 5e, whereas decreased from MIS 2 to Holocene. Moreover, the temperature difference (dT) between the surface and intermediate layers defined these phenomena. Fast warming of intermediate layer proitor to the deglaciation MIS 5/6 delayed a stratification of water column, while cooling of this layer make a large dT during MIS 1/2. Intriguingly, the faunal compositions of planktic foraminifera changed through the shifts of the

  1. Tropospheric Ozone Over the North Pacific from Ozonesdonde Observations

    NASA Technical Reports Server (NTRS)

    Oltmans, S. J.; Johnson, B. J.; Harris, J. M.; Thompson, A. M.; Liu, H. Y.; Voemel, H.; Chan, C. Y.; Fujimoto, T.; Brackett, V. G.; Chang, W. L.

    2003-01-01

    As part of the TRACE-P mission, ozone vertical profile measurements were made at a number of locations in the North Pacific. At most of the sites there is also a multi-year record of ozonesonde observations. From seven locations in the western Pacific (Hong Kong; Taipei; Jeju Island, Korea; and Naha, Kagoshima, Tsukuba, and Sapporo, Japan), a site in the central Pacific (Hilo, HI), and a site on the west coast of the U.S. (Trinidad Head, CA) both a seasonal and event specific picture of tropospheric ozone over the North Pacific emerges. At all of the sites there is a pronounced spring maximum through the troposphere. There are, however, differences in the timing and strength of this feature. Over Japan the northward movement of the jet during the spring and summer influences the timing of the seasonal maximum. The ozone profiles suggest that transport of ozone rich air from the stratosphere plays a strong role in the development of this maximum. During March and April at Hong Kong ozone is enhanced in a layer that extends from the lower free troposphere into the upper troposphere that likely has its origin in biomass burning in northern Southeast Asia and equatorial Africa. During the winter the Pacific subtropical sites (latitude -25N) are dominated by air with a low-latitude, marine source that gives low ozone amounts particularly in the upper troposphere. In the summer in the boundary layer at all of the sites marine air dominates and ozone amounts are generally quite low (less than 25 ppb). The exception is near large population centers (Tokyo and Taipei but not Hong Kong) where pollution events can give amounts in excess of 80 ppb. During the TRACE-P intensive campaign period (February-April 2001) tropospheric ozone amounts were rather typical of those seen in the long-term records of the stations with multi-year soundings.

  2. 77 FR 14351 - North Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-09

    .... Miscellaneous Issues: Bering Sea Integrated Ecosystem Research Program (BSIERP) Management Strategy Evaluation... National Oceanic and Atmospheric Administration RIN 0648-XB071 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ACTION: Notice of meetings of the North Pacific Fishery Management Council...

  3. 77 FR 65535 - North Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-29

    ... National Oceanic and Atmospheric Administration RIN 0648-XC314 North Pacific Fishery Management Council; Public Meetings AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION: Notice of public meetings. SUMMARY: The North Pacific Fishery...

  4. 77 FR 2961 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-20

    ... National Oceanic and Atmospheric Administration RIN 0648-XA945 North Pacific Fishery Management Council; Public Meeting AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION: Meeting of the North Pacific Fishery Management Council Golden King...

  5. 76 FR 49453 - North Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-10

    ... National Oceanic and Atmospheric Administration RIN 0648-XA624 North Pacific Fishery Management Council; Public Meetings AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION: Notice of public meetings. SUMMARY: The North Pacific Fishery...

  6. 78 FR 54240 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-03

    ... National Oceanic and Atmospheric Administration RIN 0648-XC844 North Pacific Fishery Management Council; Public Meeting AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION: Notice of a public meeting. SUMMARY: The North Pacific...

  7. 77 FR 67633 - North Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-13

    ... National Oceanic and Atmospheric Administration RIN 0648-XC349 North Pacific Fishery Management Council; Public Meetings AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION: Notice of public meetings. SUMMARY: The North Pacific Fishery...

  8. 78 FR 54239 - North Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-03

    ... National Oceanic and Atmospheric Administration RIN 0648-XC845 North Pacific Fishery Management Council; Public Meetings AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION: Notice of public meetings. SUMMARY: The North Pacific Fishery...

  9. 75 FR 23243 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-03

    ... National Oceanic and Atmospheric Administration RIN 0648-XW18 North Pacific Fishery Management Council; Public Meeting AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION: Notice of public meeting. SUMMARY: The North Pacific Fishery...

  10. Seasonal variability of eddy kinetic energy in the North Atlantic subtropical gyre: A high-resolution ocean model analysis

    NASA Astrophysics Data System (ADS)

    Rieck, Jan Klaus; Böning, Claus W.; Greatbatch, Richard J.; Scheinert, Markus

    2016-04-01

    A global ocean model with 1/12° horizontal resolution is used to assess the seasonal cycle of surface eddy kinetic energy (EKE) in the North Atlantic. The model reproduces the salient features of the observed mean surface EKE, including amplitude and phase of its seasonal cycle in most parts of the basin. In the interior North Atlantic subtropical gyre, EKE peaks in summer down to a depth of ˜200 m, below which the seasonal cycle is weak. Investigation of the possible driving mechanisms reveals the seasonal changes in the thermal interactions with the atmosphere to be the most likely cause of the summer maximum of EKE. The development of the seasonal thermocline in spring and summer is accompanied by stronger mesoscale variations in the horizontal temperature gradients near the surface which corresponds, by thermal wind balance, to an intensification of mesoscale velocity anomalies toward the surface. An extension of the analysis leads to similar results in the South Atlantic, North Pacific and South Pacific subtropical gyres.

  11. Measurements of deep currents in the Central North Pacific

    SciTech Connect

    Taft, B.A.; Ramp, S.R.; Dworski, J.G.; Holloway, G.

    1981-03-20

    Two deep arrays of current meters at heights of 1200 and 100 m above the bottom were set under the North Pacific Subtropical Gyre near 30 /sup 0/30'N, 157 /sup 0/45'W; the maximum record length obtained was 19 months. Autospectra show the following characteristics: strong peaks at the M2, S2 tidal frequencies; a broad peak at the diurnal-inertial peak; a spectral gap centered at 0.02 c h/sup -1/; and a regular increase in energy with decreasing frequency below the gap. Rotary components tend to be counterclockwise below 10/sup -2/ c h/sup -1/ and clockwise above the diurnal-inertial frequency. The M2 tidal amplitude ranged between 1.0 and 1.6 cm s/sup -1/; phase relationships suggest that a significant part of the motion is due to internal wave motion at this frequency. Low-pass filtered velocity statistics show the following; evidence of nonstationarity in the variances between the first (9 month) and second (10 month) arrays; significant horizontal variation of mean kinetic energy on scales of 100 km; and time-space averaged eddy kinetic energy is comparable in magnitude to the lowest values measured under the Subtropical Gyre in the western North Atlantic. Currents at 1200 m tended to be greater than at 100 m above the bottom. Spectra of the 100-m records indicate the presence of two peaks at low frequency; a dominant and ubiquitous peak in the 1/105--1/175 c d/sup -1/ frequency band; and a secondary peak, which is shown in three of four moorings, in the 1/58--1/75 c d/sup -1/ freuqncy band. Point estimates of the periods of the peaks give average values of 154 and 67 days. Comparison with subtropic western North Altantic spectra shows that the 'temporal mesoscale' period (approx.150 d) is somewhat higher in the Pacific data and it does not show the dominance of meridional motions observed in the Altantic spectra. Plane wave fits to the 154-day oscillation show the longest wave which closely fits the data has a wave length of 170 km and propagates toward 197

  12. Longitudinal Displacement of the Subtropical High in the Western Pacific in Summer and its Influence

    NASA Astrophysics Data System (ADS)

    Yang, Hui; Sun, Shuqing

    2013-04-01

    Using the relative vorticity averaged over a certain area, a new index for measuring the longitudinal position of the subtropical high (SH) in the western Pacific is proposed to avoid the increasing trend of heights in the previous indices based on geopotential height. The years of extreme westward and eastward extension of SH using the new index are in good agreement with those defined by height index. There exists a distinct difference in large-scale circulation between the eastward and westward extension of SH under the new definition, which includes not only the circulation in the middle latitudes but also the flow in the lower latitudes. It seems that when the SH extends far to the east (west), the summer monsoon in the South China Sea is stronger (weaker) and established earlier (later). In addition, there exists a good relationship between the longitudinal position of SH and the summer rainfall in China. A remarkable negative correlation area appears in the Changjiang River valley, indicating that when the SH extends westward (eastward), the precipitation in that region increases (decreases). A positive correlation region is found in South China, showing the decrease of rainfall when the SH extends westward. On the other hand, the rainfall is heavier when the SH retreats eastward. However, the anomalous longitudinal position of SH is not significantly related to the precipitation in North China. The calculation of correlation coefficients between the index of longitudinal position of SH and surface temperature in China shows that a large area of positive values, higher than 0.6 in the center, covers the whole of North China, even extending eastward to the Korean Peninsula and Japan Islands when using NCEP/NCAR reanalysis data to do the correlation calculation. This means that when the longitudinal position of the SH withdraws eastward in summer, the temperature over North China is higher. On the other hand, when it moves westward, the temperature there is

  13. 75 FR 7233 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-18

    ... National Oceanic and Atmospheric Administration RIN 0648-XU43 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ACTION: Notice of a public meeting. SUMMARY: The North Pacific Fishery...: North Pacific Fishery Management Council, 605 W. 4th Ave., Suite 306, Anchorage, AK 99501-2252....

  14. Interannual variability in the North Pacific meridional overturning circulation

    NASA Astrophysics Data System (ADS)

    Liu, Hongwei; Zhang, Qilong; Hou, Yijun; Duan, Yongliang

    2013-05-01

    We analyzed the temporal and spatial variation, and interannual variability of the North Pacific meridional overturning circulation using an empirical orthogonal function method, and calculated mass transport using Simple Ocean Data Assimilation Data from 1958-2008. The meridional streamfunction field in the North Pacific tilts N-S; the Tropical Cell (TC), Subtropical Cell (STC), and Deep Tropical Cell (DTC) may be in phase on an annual time scale; the TC and the STC are out of phase on an interannual time scale, but the interannual variability of the DTC is complex. The TC and STC interannual variability is associated with ENSO (El Niño-Southern Oscillation). The TC northward, southward, upward, and downward transports all weaken in El Niños and strengthen in La Niñas. The STC northward and southward transports are out of phase, while the STC northward and downward transports are in phase. Sea-surface water that reaches the middle latitude and is subducted may not completely return to the tropics. The zonal wind anomalies over the central North Pacific, which control Ekman transport, and the east-west slope of the sea level may be major factors causing the TC northward and southward transport interannual variability and the STC northward and southward transports on the interannual time scale. The DTC northward and southward transports decrease during strong El Niños and increase during strong La Niñas. DTC upward and downward transports are not strongly correlated with the Niño-3 index and may not be completely controlled by ENSO.

  15. Late-Quaternary climatic change on the American North Pacific Coast

    NASA Technical Reports Server (NTRS)

    Heusser, C. J.; Heusser, L. E.; Peteet, D. M.

    1985-01-01

    The late Quaternary climate of the North Pacific, where according to modelling the solar radiation in the early Holocene at the time of the summer solstice is high and in the late Holocene is relatively low, is investigated. Quantitative temperature and precipitation estimates from southern Alaska are compared with estimates from western Washington and British Columbia. Data extending over more than 10,000 years show a broadly consistent pattern of climatic change in general agreement with predicted variations in solar radiation and their effect on atmospheric circulation and seasonal duration of pressure systems over the North Pacific Ocean. In the early Holocene, the subtropical North Pacific anticyclone annually regulated climate for a longer period at higher latitudes than at present, so that warmth and dryness increased in southern Alaska. The Aleutian low-pressure center intensified during the late Holocene, resulting in colder and more humid coastal climate and increased frequency of glacier growth in the cordillera.

  16. Sensors detect biological change in mid-latitude North Pacific

    NASA Astrophysics Data System (ADS)

    Polovina, Jeffrey J.; Seki, Michael P.; Howell, Evan

    High temporal and spatial resolution ocean color data for the global ocean were collected for January-June 1997 by the Ocean Color and Temperature Scanner (OCTS) from the Japanese ADEOS satellite and for September 1997 to the present by the Sea-viewing Wide Field-of-view sensor (SeaWiFS). These sensors show the North Pacific Subtropical Gyre characterized by surface chlorophyll less than 0.15 mg/m3, while to the north, the Transition Zone and Subarctic Gyre exhibit surface chlorophyll in excess of 0.25 mg/m3 (Figure 1). The boundary between the low and high chlorophyll domains can be characterized by the 0.2 mg/m3 chlorophyll contour line (Figure l). This boundary is termed the Transition Zone Chlorophyll Front (TZCF) because it moves seasonally between the southern and northern limits of the Transition Zone, coinciding with the convergence of cool, vertically mixed, high chlorophyll water found to the north with warmer, stratified, low chlorophyll water on the south. In addition to simply marking the separation between high and low chlorophyll regions, the TZCF is used as a migratory and forage habitat by apex predators including sea turtles and tunas [Polovina et al., 2000].

  17. Satellite remote sounding of atmospheric boundary layer temperature inversions over the subtropical eastern Pacific

    NASA Astrophysics Data System (ADS)

    Fetzer, Eric J.; Teixeira, Joao; Olsen, Edward T.; Fishbein, Evan F.

    2004-09-01

    We describe atmospheric temperature inversions and height-resolved water vapor fields over the wintertime subtropical northeastern Pacific Ocean in observations by the satellite-borne Atmospheric Infrared Sounder (AIRS) experiment. A comparison with model analyses shows good agreement in temperature. Water vapor comparisons with operational radiosondes at four sites in California and Hawaii during December 2002-January 2003 have low biases in the 1000-700 and 700-500 hPa layers. Maps of inversion frequency, and, water vapor at 1000-700 and 700-500 hPa over the subtropical northeast Pacific during 1-16 January 2003-when high pressure and clear conditions prevail-show inversions occurring at a local minimum in water vapor at 1000-700 hPa. Water vapor at 700-500 hPa has a broad minimum extending from Baja California to Hawaii, with inversions found on its eastern half. These observations illustrate the potential of the AIRS data for describing a climatology of temperature and water vapor in subtropical oceanic regions.

  18. News insights of the hydrology of the Northwestern subtropical Pacific Ocean from ɛNd investigations of the South China Sea sediments

    NASA Astrophysics Data System (ADS)

    Wu, Q.; Christophe, C.; Liu, Z.; Douville, E.; Dubois-Dauphin, Q.

    2015-12-01

    Seawater Nd isotopic composition (ɛNd) extracted from planktonic foraminifera G. ruber have been investigated on core MD05-2904 located on the northwestern margin of the South China Sea (SCS) at 2000 m water depth to reconstruct hydrological variations since the Last Glacial Maximum (LGM) of the western subtropical North Pacific that still poorly documented. For the last 25 kyr, ɛNd values obtained on foraminifera present large range from -4 to -6.7 suggesting large changes in the contribution of the NPDW (ɛNd = -4) and the UCDW (ɛNd -6 to -8) in the western Pacific. The glacial ɛNd values (~ -6.5) are interestingly similar to those obtained in the South Atlantic and in the Indian Ocean during the LGM and indicate a strong northward propagation of the Southern Sourced Water (SSW) in the subtropical western North Pacific. During the deglaciation, ɛNd records indicate a relatively decreased proportion of the SSW in the deep-water component of the western subtropical Pacific interrupted by two negative excursions of the ɛNd implying higher proportion of SSW during the time intervals 17 - 15 cal kyr BP and 10 - 8 cal kyr BP coeval to the Heinrich Statial 1 (HS1) and the early Holocene. The seawater ɛNd record is also well correlated to δ13C record obtained on benthic foraminifera Cibicides wuellerstorfi of the SCS and Southern Ocean confirming that ɛNd record reflect global circulation changes. The negative shifts centered on the Heinrich Statial 1 (HS1) is coeval with an enhanced upwelling in the Southern Ocean associated to pole wards shifts of the southern westerly inducing a enhanced formation of the SSW that propagate to the subtropical western Pacific. The negative excursion of the ɛNd during the Early Holocene (~10 - 8 cal kyr BP) indicate a relatively higher proportion of the SSW that could be associated to a higher production of the SSW as it was already recently observed in the South Atlantic and/or a possible reduction of the NPIW in the North

  19. Characteristics and mechanism of sub-seasonal zonal oscillation of western Pacific subtropical high and South Asian high

    NASA Astrophysics Data System (ADS)

    Ren, Xuejuan

    2016-04-01

    The Asian monsoon circulations, like the western Pacific subtropical high (WPSH) at 500hPa and South Asian high (SAH) in the upper level, demonstrate sub-seasonal zonal oscillation. The WPSH is characterized by anomalously westward extension of its western edge with anomalous low-level anti-cyclonic circulation over the coastal region prior and eastward retreat with low-level cyclonic anomalies afterward, contributing persistent heavy rainfall over the Middle-lower reaches of the Yangtze River Valley. The coastal SST anomalies linked with zonal movement of WPSH shows cooling phase to warming phase variations. A local air-sea interaction on sub-seasonal time-scale in the western North Pacific region, which may be responsible for generating WPSH's sub-seasonal zonal oscillation. The SAH's eastward extension is featured by eastward propagation of wavetrain across the Eurasian continent. When the SAH extends to its easternmost position, a strong negative PV (positive geopotential height) center prevails to the east of the Tibetan Plateau at 200hPa. The causes of SAH's eastward extension are examined by performing potential vorticity (PV) diagnosis with emphasis on the joint role of diabatic heating feedback/rainfall and midlatitude wavetrain. The PV diagnosis indicates that the anomalous heating/rainfall and ascending motion generate negative PV anomalies at 200hPa directly over north China-east Mongolia. While anomalous cooling and descending motion produce positive PV anomalies over south China. Those south/north dipolar structure of PV generation indicates large value of meridional gradient of PV anomalies. As a consequence, the negative PV anomalies over the north lobe are transported southwardly by the advection of climatological northerly located to the east and southeast of the Tibetan Plateau.

  20. Evaluating the impacts of eastern North Pacific tropical cyclones on North America utilizing remotely-sensed and reanalysis data

    NASA Astrophysics Data System (ADS)

    Wood, Kimberly M.

    The eastern North Pacific Ocean has the highest density of tropical cyclone genesis events of any tropical basin in the world, and many of these systems form near land before moving westward. However, despite the level of tropical cyclone activity in this basin, and the proximity of the main genesis region to land, tropical cyclone behavior in the eastern North Pacific has been relatively unexplored. When synoptic conditions are favorable, moisture from northward-moving tropical cyclones can be advected into northern Mexico and the southwestern United States, often leading to the development of summertime thunderstorms during the North American monsoon season. An interaction with a mid-latitude trough produces the most rainfall, and the spatial variability of precipitation is greatly affected by the complex topography of the region. Moisture can be advected from a tropical cyclone around the subtropical ridge in place for much of the eastern North Pacific hurricane season and contribute to precipitation. This ridge, when it extends westward over the Pacific Ocean, can also prevent tropical cyclone moisture from impacting the southwestern United States. Northward-moving tropical cyclones often enter an environment with decreasing sea surface temperatures, increasing vertical wind shear, and meridional air temperature and moisture gradients. These key ingredients for extratropical transition are generally present in the eastern North Pacific, but the subtropical ridge prevents many named systems from moving northward, and only 9% of eastern North Pacific tropical cyclones from 1970 to 2011 complete ET according to cyclone phase space. However, over half of the systems that do not complete ET dissipate as cold core cyclones, a structural change that has yet to be explored in other tropical basins. It is difficult to estimate tropical cyclone intensity in a vast ocean area with few direct measurements available. The deviation angle variance technique, an objective

  1. Subtropical Potential Vorticity Intrusion Drives Increasing Tropospheric Ozone over the Tropical Central Pacific.

    PubMed

    Nath, Debashis; Chen, Wen; Graf, Hans-F; Lan, Xiaoqing; Gong, Hainan; Nath, Reshmita; Hu, Kaiming; Wang, Lin

    2016-02-12

    Drawn from multiple reanalysis datasets, an increasing trend and westward shift in the number of Potential Vorticity intrusion events over the Pacific are evident. The increased frequency can be linked to a long-term trend in upper tropospheric equatorial westerly wind and subtropical jets during boreal winter to spring. These may be resulting from anomalous warming and cooling over the western Pacific warm pool and the tropical eastern Pacific, respectively. The intrusions brought dry and ozone rich air of stratospheric origin deep into the tropics. In the tropical upper troposphere, interannual ozone variability is mainly related to convection associated with El Niño/Southern Oscillation. Zonal mean stratospheric overturning circulation organizes the transport of ozone rich air poleward and downward to the high and midlatitudes leading there to higher ozone concentration. In addition to these well described mechanisms, we observe a long-term increasing trend in ozone flux over the northern hemispheric outer tropical (10-25°N) central Pacific that results from equatorward transport and downward mixing from the midlatitude upper troposphere and lower stratosphere during PV intrusions. This increase in tropospheric ozone flux over the Pacific Ocean may affect the radiative processes and changes the budget of atmospheric hydroxyl radicals.

  2. Subtropical Potential Vorticity Intrusion Drives Increasing Tropospheric Ozone over the Tropical Central Pacific

    NASA Astrophysics Data System (ADS)

    Nath, Debashis; Chen, Wen; Graf, Hans-F.; Lan, Xiaoqing; Gong, Hainan; Nath, Reshmita; Hu, Kaiming; Wang, Lin

    2016-02-01

    Drawn from multiple reanalysis datasets, an increasing trend and westward shift in the number of Potential Vorticity intrusion events over the Pacific are evident. The increased frequency can be linked to a long-term trend in upper tropospheric equatorial westerly wind and subtropical jets during boreal winter to spring. These may be resulting from anomalous warming and cooling over the western Pacific warm pool and the tropical eastern Pacific, respectively. The intrusions brought dry and ozone rich air of stratospheric origin deep into the tropics. In the tropical upper troposphere, interannual ozone variability is mainly related to convection associated with El Niño/Southern Oscillation. Zonal mean stratospheric overturning circulation organizes the transport of ozone rich air poleward and downward to the high and midlatitudes leading there to higher ozone concentration. In addition to these well described mechanisms, we observe a long-term increasing trend in ozone flux over the northern hemispheric outer tropical (10-25°N) central Pacific that results from equatorward transport and downward mixing from the midlatitude upper troposphere and lower stratosphere during PV intrusions. This increase in tropospheric ozone flux over the Pacific Ocean may affect the radiative processes and changes the budget of atmospheric hydroxyl radicals.

  3. Subtropical Potential Vorticity Intrusion Drives Increasing Tropospheric Ozone over the Tropical Central Pacific

    PubMed Central

    Nath, Debashis; Chen, Wen; Graf, Hans-F.; Lan, Xiaoqing; Gong, Hainan; Nath, Reshmita; Hu, Kaiming; Wang, Lin

    2016-01-01

    Drawn from multiple reanalysis datasets, an increasing trend and westward shift in the number of Potential Vorticity intrusion events over the Pacific are evident. The increased frequency can be linked to a long-term trend in upper tropospheric equatorial westerly wind and subtropical jets during boreal winter to spring. These may be resulting from anomalous warming and cooling over the western Pacific warm pool and the tropical eastern Pacific, respectively. The intrusions brought dry and ozone rich air of stratospheric origin deep into the tropics. In the tropical upper troposphere, interannual ozone variability is mainly related to convection associated with El Niño/Southern Oscillation. Zonal mean stratospheric overturning circulation organizes the transport of ozone rich air poleward and downward to the high and midlatitudes leading there to higher ozone concentration. In addition to these well described mechanisms, we observe a long-term increasing trend in ozone flux over the northern hemispheric outer tropical (10–25°N) central Pacific that results from equatorward transport and downward mixing from the midlatitude upper troposphere and lower stratosphere during PV intrusions. This increase in tropospheric ozone flux over the Pacific Ocean may affect the radiative processes and changes the budget of atmospheric hydroxyl radicals. PMID:26868836

  4. Subtropical Potential Vorticity Intrusion Drives Increasing Tropospheric Ozone over the Tropical Central Pacific.

    PubMed

    Nath, Debashis; Chen, Wen; Graf, Hans-F; Lan, Xiaoqing; Gong, Hainan; Nath, Reshmita; Hu, Kaiming; Wang, Lin

    2016-01-01

    Drawn from multiple reanalysis datasets, an increasing trend and westward shift in the number of Potential Vorticity intrusion events over the Pacific are evident. The increased frequency can be linked to a long-term trend in upper tropospheric equatorial westerly wind and subtropical jets during boreal winter to spring. These may be resulting from anomalous warming and cooling over the western Pacific warm pool and the tropical eastern Pacific, respectively. The intrusions brought dry and ozone rich air of stratospheric origin deep into the tropics. In the tropical upper troposphere, interannual ozone variability is mainly related to convection associated with El Niño/Southern Oscillation. Zonal mean stratospheric overturning circulation organizes the transport of ozone rich air poleward and downward to the high and midlatitudes leading there to higher ozone concentration. In addition to these well described mechanisms, we observe a long-term increasing trend in ozone flux over the northern hemispheric outer tropical (10-25°N) central Pacific that results from equatorward transport and downward mixing from the midlatitude upper troposphere and lower stratosphere during PV intrusions. This increase in tropospheric ozone flux over the Pacific Ocean may affect the radiative processes and changes the budget of atmospheric hydroxyl radicals. PMID:26868836

  5. Subtropical Low Cloud Responses to Central and Eastern Pacific El Nino Events

    NASA Astrophysics Data System (ADS)

    Rapp, A. D.; Bennartz, R.; Jiang, J. H.; Kato, S.; Olson, W. S.; Pinker, R. T.; Su, H.; Taylor, P. C.

    2014-12-01

    The eastern Pacific El Niño event in 2006-2007 and the central Pacific El Niño event during 2009-2010 exhibit opposite responses in the top of atmosphere (TOA) cloud radiative effects. These responses are driven by differences in large-scale circulation that result in significant low cloud anomalies in the subtropical southeastern Pacific. Both the vertical profile of cloud fraction and cloud water content are reduced during the eastern Pacific El Niño; however, the shift in the distribution of cloud characteristics and the physical processes underlying these changes need further analysis. The NASA Energy and Water Cycle Study (NEWS) Clouds and Radiation Working Group will use a synthesis of NEWS data products, A-Train satellite measurements, reanalysis, and modeling approaches to further explore the differences in the low cloud response to changes in the large-scale forcing, as well as try to understand the physical mechanism driving the observed changes in the low clouds for the 2006/07 and 2009/10 distinct El Niño events. The distributions of cloud macrophysical, microphysical, and radiative properties over the southeast Pacific will first be compared for these two events using a combination of MODIS, CloudSat/CALIPSO, and CERES data. Satellite and reanalysis estimates of changes in the vertical temperature and moisture profiles, lower tropospheric stability, winds, and surface heat fluxes are then used to identify the drivers for observed differences in the clouds and TOA radiative effects.

  6. 78 FR 16660 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-18

    ... National Oceanic and Atmospheric Administration RIN 0648-XC556 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ACTION: Notice of public meetings. SUMMARY: The North Pacific Fishery Management... Hilton Hotel, Dillingham/Katmai Room, 500 West 3rd Avenue, Anchorage, AK. Council address: North...

  7. Rapid subtropical North Atlantic salinity oscillations across Dansgaard-Oeschger cycles.

    PubMed

    Schmidt, Matthew W; Vautravers, Maryline J; Spero, Howard J

    2006-10-01

    Geochemical and sedimentological evidence suggest that the rapid climate warming oscillations of the last ice age, the Dansgaard-Oeschger cycles, were coupled to fluctuations in North Atlantic meridional overturning circulation through its regulation of poleward heat flux. The balance between cold meltwater from the north and warm, salty subtropical gyre waters from the south influenced the strength and location of North Atlantic overturning circulation during this period of highly variable climate. Here we investigate how rapid reorganizations of the ocean-atmosphere system across these cycles are linked to salinity changes in the subtropical North Atlantic gyre. We combine Mg/Ca palaeothermometry and oxygen isotope ratio measurements on planktonic foraminifera across four Dansgaard-Oeschger cycles (spanning 45.9-59.2 kyr ago) to generate a seawater salinity proxy record from a subtropical gyre deep-sea sediment core. We show that North Atlantic gyre surface salinities oscillated rapidly between saltier stadial conditions and fresher interstadials, covarying with inferred shifts in the Tropical Atlantic hydrologic cycle and North Atlantic overturning circulation. These salinity oscillations suggest a reduction in precipitation into the North Atlantic and/or reduced export of deep salty thermohaline waters during stadials. We hypothesize that increased stadial salinities preconditioned the North Atlantic Ocean for a rapid return to deep overturning circulation and high-latitude warming by contributing to increased North Atlantic surface-water density on interstadial transitions.

  8. Rapid subtropical North Atlantic salinity oscillations across Dansgaard-Oeschger cycles.

    PubMed

    Schmidt, Matthew W; Vautravers, Maryline J; Spero, Howard J

    2006-10-01

    Geochemical and sedimentological evidence suggest that the rapid climate warming oscillations of the last ice age, the Dansgaard-Oeschger cycles, were coupled to fluctuations in North Atlantic meridional overturning circulation through its regulation of poleward heat flux. The balance between cold meltwater from the north and warm, salty subtropical gyre waters from the south influenced the strength and location of North Atlantic overturning circulation during this period of highly variable climate. Here we investigate how rapid reorganizations of the ocean-atmosphere system across these cycles are linked to salinity changes in the subtropical North Atlantic gyre. We combine Mg/Ca palaeothermometry and oxygen isotope ratio measurements on planktonic foraminifera across four Dansgaard-Oeschger cycles (spanning 45.9-59.2 kyr ago) to generate a seawater salinity proxy record from a subtropical gyre deep-sea sediment core. We show that North Atlantic gyre surface salinities oscillated rapidly between saltier stadial conditions and fresher interstadials, covarying with inferred shifts in the Tropical Atlantic hydrologic cycle and North Atlantic overturning circulation. These salinity oscillations suggest a reduction in precipitation into the North Atlantic and/or reduced export of deep salty thermohaline waters during stadials. We hypothesize that increased stadial salinities preconditioned the North Atlantic Ocean for a rapid return to deep overturning circulation and high-latitude warming by contributing to increased North Atlantic surface-water density on interstadial transitions. PMID:17024090

  9. Variability in subtropical-tropical cells drives oxygen levels in the tropical Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Duteil, Olaf; Böning, Claus W.; Oschlies, Andreas

    2014-12-01

    Previous studies found a negative trend in oxygen concentrations in tropical regions during the last decades. Employing a biogeochemical circulation model, we highlight the importance of wind-driven ocean transport associated with the Subtropical-Tropical Cells (STCs) in setting the oxygen levels in the tropical ocean. The observed and simulated slowdown of the STCs by 30% from the 1960s to the 1990s caused a decrease in oxygen transport to the tropics. Transport of phosphate was similarly reduced, decreasing export production and respiration. The effects of physical transport and biological consumption partly compensate, damping oxygen interannual and decadal variability. Our results suggest that the observed residual oxygen trend in the tropical Pacific is mainly driven by changes in oxygen transport. Accordingly, the observed recent strengthening of the STCs leads us to expect a pause in the oxygen decrease or even an increase of tropical Pacific oxygen values in the near future.

  10. Variability in subtropical-tropical cells drives oxygen levels in the tropical Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Duteil, Olaf; Böning, Claus W.; Oschlies, Andreas

    2015-04-01

    Previous studies found a negative trend in oxygen concentrations in tropical regions during the last decades. Employing a biogeochemical circulation model, we highlight the importance of wind-driven ocean transport associated with the Subtropical-Tropical Cells (STCs) in setting the oxygen levels in the tropical ocean. The observed and simulated slowdown of the STCs by 30% from the 1960s to the 1990s caused a decrease in oxygen transport to the tropics. Transport of phosphate was similarly reduced, decreasing export production and respiration. The effects of physical transport and biological consumption partly compensate, damping oxygen interannual and decadal variability. Our results suggest that the observed residual oxygen trend in the tropical Pacific is mainly driven by changes in oxygen transport. Accordingly, the observed recent strengthening of the STCs leads us to expect a pause in the oxygen decrease or even an increase of tropical Pacific oxygen values in the near future.

  11. Orbital control of the western North Pacific summer monsoon

    NASA Astrophysics Data System (ADS)

    Wu, Chi-Hua; Chiang, John C. H.; Hsu, Huang-Hsiung; Lee, Shih-Yu

    2016-02-01

    Orbital forcing exerts a strong influence on global monsoon systems, with higher summer insolation leading to stronger summer monsoons in the Northern Hemisphere. However, the associated regional and seasonal changes, particularly the interaction between regional monsoon systems, remain unclear. Simulations using the Community Earth System Model demonstrate that the western North Pacific (WNP) summer monsoon responds to orbital forcing opposite to that of other major Northern Hemisphere monsoon systems. Compared with its current climate state, the simulated WNP monsoon and associated lower-tropospheric trough is absent in the early Holocene when the precession-modulated Northern Hemisphere summer insolation is higher, whereas the summer monsoons in South and East Asia are stronger and shift farther northward. We attribute the weaker WNP monsoon to the stronger diabatic heating of the summer Asian monsoon—in particular over the southern Tibetan Plateau and Maritime Continent—that in turn strengthens the North Pacific subtropical high through atmospheric teleconnections. By contrast, the impact of the midlatitude circulation changes on the WNP monsoon is weaker when the solar insolation is higher. Prior to the present WNP monsoon onset, the upper-tropospheric East Asian jet stream weakens and shifts northward; the monsoon onset is highly affected by the jet-induced high potential vorticity intrusion. In the instance of the extreme perihelion-summer, the WNP monsoon is suppressed despite a stronger midlatitude precursor than present-day, and the midlatitude circulation response to the enhanced South Asian precipitation is considerable. These conditions indicate internal monsoon interactions of an orbital scale, implying a potential mechanistic control of the WNP monsoon.

  12. Relationship Between Intraseasonal Oscillation and Subtropical Wind Maxima Over the South Pacific Ocean

    NASA Technical Reports Server (NTRS)

    Vincent, Dayton G.; Hurrell, James W.; Speth, P.; Sperling, T.; Funk, A.; Zube, S.

    1991-01-01

    The significance of tropical heat sources on higher latitude jet streams has been examined by numerous investigators. Hurrell and Vincent (1990) provide a summary of many of these investigations in their observational case study of the relationship between tropical heating and subtropical wind maxima in the Southern Hemisphere during SOP-1, FGGE. They showed that the divergent outflow from tropical heating associated with the South Pacific Convergence Zone (SPCZ), acted on by the coriolis force, was an important factor in maintaining the subtropical jet on the poleward side of the SPCZ during the period, 6-20 January 1979. They found a similar, but weaker relationship, over the southern Indian Ocean from 3-17 February 1979, a period when the SPCZ heating was greatly reduced and the jet was essentially non-existent. Since their findings were based on a case study and involved the use of the highly-specialized FGGE data set, the natural questions which arose were: (1) Is this relationship a regular feature of the circulation over the South Pacific? and, (2) If so, can it be detected with a routine data set? Another question posed by Hurrell and Vincent in their papers was:(3) How important was the intraseasonal oscillation in causing the enhanced heating and divergent outflow in the Pacific Ocean in January and southern Indian Ocean in February? The purpose of the present paper is to address the answer to these three questions. To accomplish this, some circulation features for an entire warm season in the Southern Hemisphere were examined. The year selected was 1984-85, and the warm season consisted of the 6-month period, 1 November 1984 - 30 April 1985. This period was chosen because there were numerous cases of the westerly wind maxima over the South Pacific and the intraseasonal oscillation was well documented.

  13. [Costa Rica mangroves: the north Pacific].

    PubMed

    Zamora-Trejos, Priscilla; Cortés, Jorge

    2009-09-01

    Costa Rica has mangrove forests on both the Caribbean and Pacific coasts. The Pacific side has 99% of the mangrove area of the country. In this review we compile available information on the mangroves of the north Pacific coast of Costa Rica, from Bahía Salinas, on the border with Nicaragua, to the tip of the Peninsula de Nicoya at Cabo Blanco. We provide information on the location of the mangroves and all available information for each mangrove forest. These mangrove communities are smaller in extension and tree sizes, and have lower diversity compared to the mangroves on the southern section of the Pacific coast of Costa Rica. The dominant species are Rhizophora mangle and Rhizophora racemosa along the canal edges, backed by Avicennia germinans, and farther inland Avicennia bicolor, Laguncularia racemosa and Conocarpus erectus. At Potrero Grande a healthy population of Pelliciera rhizophorae, a rare species, has been reported. We recognized 38 mangrove communities in this part of the country, based on the National Wetland Inventory, published papers, field observations, theses, technical reports, and the national topographic maps (1:50,000, Instituto Geográfico Nacional). Relatively detailed information could be found for only five mangrove forests, for 14 more only prelimary and incomplete lists of plants and in some cases of animal species are available, for nine there is even less information, and for nine more only their location is known, which in some cases was not correct. Detail mapping, characterization of the vegetation and fauna, physiological studies, analyses of biogeochemical and physical processes, economic valuations, and determination of the health status of the mangrove of the northern Pacific coast, as well as for the rest of Costa Rica, are neccesary and urgent.

  14. [Costa Rica mangroves: the north Pacific].

    PubMed

    Zamora-Trejos, Priscilla; Cortés, Jorge

    2009-09-01

    Costa Rica has mangrove forests on both the Caribbean and Pacific coasts. The Pacific side has 99% of the mangrove area of the country. In this review we compile available information on the mangroves of the north Pacific coast of Costa Rica, from Bahía Salinas, on the border with Nicaragua, to the tip of the Peninsula de Nicoya at Cabo Blanco. We provide information on the location of the mangroves and all available information for each mangrove forest. These mangrove communities are smaller in extension and tree sizes, and have lower diversity compared to the mangroves on the southern section of the Pacific coast of Costa Rica. The dominant species are Rhizophora mangle and Rhizophora racemosa along the canal edges, backed by Avicennia germinans, and farther inland Avicennia bicolor, Laguncularia racemosa and Conocarpus erectus. At Potrero Grande a healthy population of Pelliciera rhizophorae, a rare species, has been reported. We recognized 38 mangrove communities in this part of the country, based on the National Wetland Inventory, published papers, field observations, theses, technical reports, and the national topographic maps (1:50,000, Instituto Geográfico Nacional). Relatively detailed information could be found for only five mangrove forests, for 14 more only prelimary and incomplete lists of plants and in some cases of animal species are available, for nine there is even less information, and for nine more only their location is known, which in some cases was not correct. Detail mapping, characterization of the vegetation and fauna, physiological studies, analyses of biogeochemical and physical processes, economic valuations, and determination of the health status of the mangrove of the northern Pacific coast, as well as for the rest of Costa Rica, are neccesary and urgent. PMID:19928448

  15. A Decadal-Scale Teleconnection between the North Atlantic Oscillation and Subtropical Eastern Australian Rainfall

    NASA Astrophysics Data System (ADS)

    Li, J.

    2015-12-01

    The time series of twentieth-century subtropical eastern Australian rainfall (SEAR) shows evident fluctuations over decadal to multidecadal time scales. Using observations from the period 1900-2013, it was found that SEAR is connected to the North Atlantic Oscillation (NAO) over decadal time scales, with the NAO leading by around 15 yr. The physical mechanism underlying this relationship was investigated. The NAO can have a delayed impact on sea surface temperature (SST) fluctuations in the subpolar Southern Ocean (SO), and these SST changes could in turn contribute to the decadal variability in SEAR through their impacts on the Southern Hemisphere atmospheric circulation. This observed lead of the NAO relative to SO SST and the interhemispheric SST seesaw mechanism are reasonably reproduced in a long-term control simulation of an ocean-atmosphere coupled model. The NAO exerts a delayed effect on the variation of Atlantic meridional overturning circulation that further induces seesaw SST anomalies in the subpolar North Atlantic and SO. With evidence that the NAO precedes SEAR decadal variability via a delayed SO bridge, a linear model for SEAR decadal variability was developed by combination of the NAO and Pacific decadal oscillation (PDO). The observed SEAR decadal variability is considerably well simulated by the linear model, and the relationship between the simulation and observation is stable. SEAR over the coming decade may increase slightly, because of the recent NAO weakening and the return of negative PDO phase.The time series of twentieth-century subtropical eastern Australian rainfall (SEAR) shows evident fluctuations over decadal to multidecadal time scales. Using observations from the period 1900-2013, it was found that SEAR is connected to the North Atlantic Oscillation (NAO) over decadal time scales, with the NAO leading by around 15 yr. The physical mechanism underlying this relationship was investigated. The NAO can have a delayed impact on sea

  16. Southward spreading of the Fukushima-derived radiocesium across the Kuroshio Extension in the North Pacific.

    PubMed

    Kumamoto, Yuichiro; Aoyama, Michio; Hamajima, Yasunori; Aono, Tatsuo; Kouketsu, Shinya; Murata, Akihiko; Kawano, Takeshi

    2014-03-04

    The accident of the Fukushima Dai-ichi nuclear power plant in March 2011 released a large amount of radiocesium into the North Pacific Ocean. Vertical distributions of Fukushima-derived radiocesium were measured at stations along the 149°E meridian in the western North Pacific during the winter of 2012. In the subtropical region, to the south of the Kuroshio Extension, we found a subsurface radiocesium maximum at a depth of about 300 m. It is concluded that atmospheric-deposited radiocesium south of the Kuroshio Extension just after the accident had been transported not only eastward along with surface currents but also southward due to formation/subduction of subtropical mode waters within about 10 months after the accident. The total amount of decay-corrected (134)Cs in the mode water was an estimated about 6 PBq corresponding to 10-60% of the total inventory of Fukushima-derived (134)Cs in the North Pacific Ocean.

  17. Southward spreading of the Fukushima-derived radiocesium across the Kuroshio Extension in the North Pacific

    PubMed Central

    Kumamoto, Yuichiro; Aoyama, Michio; Hamajima, Yasunori; Aono, Tatsuo; Kouketsu, Shinya; Murata, Akihiko; Kawano, Takeshi

    2014-01-01

    The accident of the Fukushima Dai-ichi nuclear power plant in March 2011 released a large amount of radiocesium into the North Pacific Ocean. Vertical distributions of Fukushima-derived radiocesium were measured at stations along the 149°E meridian in the western North Pacific during the winter of 2012. In the subtropical region, to the south of the Kuroshio Extension, we found a subsurface radiocesium maximum at a depth of about 300 m. It is concluded that atmospheric-deposited radiocesium south of the Kuroshio Extension just after the accident had been transported not only eastward along with surface currents but also southward due to formation/subduction of subtropical mode waters within about 10 months after the accident. The total amount of decay-corrected 134Cs in the mode water was an estimated about 6 PBq corresponding to 10–60% of the total inventory of Fukushima-derived 134Cs in the North Pacific Ocean. PMID:24589762

  18. Bottom water variability in the subtropical northwestern Pacific from 26 kyr BP to present based on Mg / Ca and stable carbon and oxygen isotopes of benthic foraminifera

    NASA Astrophysics Data System (ADS)

    Kubota, Y.; Kimoto, K.; Itaki, T.; Yokoyama, Y.; Miyairi, Y.; Matsuzaki, H.

    2015-06-01

    To understand bottom water variability in the subtropical northwestern Pacific, bottom water temperatures (BWTs), carbon isotopes (δ13C), and oxygen isotopes of seawater (δ18Ow) at a water depth of 1166 m were reconstructed from 26 kyr BP to present. A new regional Mg / Ca calibration for the benthic foraminifera Cibicidoides wuellerstorfi (type B) was established to convert the benthic Mg / Ca value to BWT, based on 26 surface sediment samples and two core-top samples retrieved around Okinawa Island. During the Last Glacial Maximum (LGM), the δ18Ow in the intermediate water in the northwestern South Pacific was ~0.4‰ lower than in the deep South Pacific, indicating a greater vertical salinity gradient than at present. This salinity (and probably density) structure would have led to stratification in the intermediate and deep Pacific, which would, in turn, have greatly influenced carbon storage during the glacial time. The benthic Mg / Ca and δ18Ow records suggest changes that seem to follow Heinrich event 1 (H1) and the Bølling-Alleød (B/A) and Younger Dryas (YD) intervals, with BWT higher during H1 (~17 kyr BP) and YD (~12 kyr BP) and lower during B/A (~14 kyr BP). The warming in the bottom water during H1 suggests increased contribution of North Pacific Intermediate Water (NPIW) to the subtropical northwestern Pacific and decreased upwelling of cooler waters from the abyssal North Pacific. During the interval from 17 to 14.5 kyr BP, the BWT tended to decrease successively in association with a decrease in δ13C values, presumably as a result of increased upwelling of the abyssal waters to the intermediate depths of the North Pacific caused by shoaling and enhancement of the southward return flow of Pacific Deep Water (PDW). During the Holocene, the millennial- to sub-millennial-scale variations in the BWT generally correlate with the sea surface temperatures in the Okhotsk Sea, the source region of the NPIW, suggesting that changes in the BWT are linked

  19. BrO in the Tropical and Subtropical UTLS: Longitudinal Gradients over the Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Volkamer, R. M.; Dix, B. K.; Baidar, S.; Koenig, T. K.; Coburn, S.; Ortega, I.; Chen, D.; Huey, L. G.; Tanner, D.; Sherwen, T.; Evans, M. J.; Apel, E. C.; Hornbrook, R. S.; Blake, N. J.; Hills, A. J.; Kinnison, D. E.; Lamarque, J. F.; Saiz-Lopez, A.; Pierce, R. B.; Schmidt, J.; Jacob, D. J.; Atlas, E. L.; Pan, L.; Salawitch, R. J.

    2014-12-01

    Bromine oxide (BrO) is a halogen radical that catalytically destroys ozone, modifies the oxidative capacity of the atmosphere and oxidizes atmospheric mercury. About 75% of the global tropospheric ozone loss occurs at tropical latitudes, where the ozone radiative forcing is most sensitive to changes in the ozone concentration. Here we report on BrO observations in the tropical and sub-tropical free troposphere and UTLS. Airborne measurements of BrO vertical profiles were performed by the University of Colorado Airborne Multi Axis DOAS (CU AMAX-DOAS) instrument aboard the NSF/NCAR GV aircraft. We compare BrO profiles measured at tropical and subtropical latitudes over the Western Pacific (CONvective TRansport of Active Species in the Tropics, CONTRAST, field campaign) with tropical BrO profiles measured over the Central (Mauna Loa Observatory fly-by) and Eastern Pacific ocean (Tropical Ocean tRoposphere Exchange of Reactive halogen species and Oxygenated VOC, TORERO, experiment). For selected case studies we compare BrO profiles from three independent instruments, i.e., CU AMAX-DOAS, mountain-top MAX-DOAS at Mauna Loa Observatory, and Chemical Ionization Mass Spectrometry and BrO predictions from global models (CAM-Chem, GEOS-Chem and RAQMS).

  20. What drives seasonal change in oligotrophic area in the subtropical North Atlantic?

    NASA Astrophysics Data System (ADS)

    Dave, Apurva C.; Barton, Andrew D.; Lozier, M. Susan; McKinley, Galen A.

    2015-06-01

    The oligotrophic regions of the subtropical gyres cover a significant portion of the global ocean, and exhibit considerable but poorly understood intraseasonal, interannual, and longer-term variations in spatial extent. Here using historical observations of surface ocean nitrate, wind, and currents, we have investigated how horizontal and vertical supplies of nitrate control seasonal changes in the size and shape of oligotrophic regions of the subtropical North Atlantic. In general, the oligotrophic region of the subtropical North Atlantic is associated with the region of weak vertical supply of nitrate. Though the total vertical supply of nitrate here is generally greater than the total horizontal supply, we find that seasonal expansion and contraction of the oligotrophic region is consistent with changes in horizontal supply of nitrate. In this dynamic periphery of the subtropical gyre, the seasonal variations in chlorophyll are linked to variations in horizontal nitrate supply that facilitate changes in intracellular pigment concentrations, and to a lesser extent, phytoplankton biomass. Our results suggest that horizontal transports of nutrient are crucial in setting seasonal cycles of chlorophyll in large expanses of the subtropical North Atlantic, and may play a key and underappreciated role in regulating interannual variations in these globally important marine ecosystems.

  1. Nitrogen isotope ratios of nitrate and N* anomalies in the subtropical South Pacific

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Chisato; Makabe, Akiko; Shiozaki, Takuhei; Toyoda, Sakae; Yoshida, Osamu; Furuya, Ken; Yoshida, Naohiro

    2015-05-01

    Nitrogen isotopic ratios of nitrate (δ15N-NO3-) were analyzed above 1000 m water depth along 17°S in the subtropical South Pacific during the revisit WOCE P21 cruise in 2009. The δ15N-NO3- and N* values were as high as 17‰ and as low as -18 μmol N L-1, respectively, at depths around 250 m east of 115°W, but were as low as 5‰ and as high as +1 μmol N L-1, respectively, in subsurface waters west of 170°W. The relationships among NO3- concentrations, N* values, δ15N-NO3- values, and oxygen and nitrite concentrations suggest that a few samples east of 90°W were from suboxic and nitrite-accumulated conditions and were possibly affected by in situ water column denitrification. Most of the high-δ15N-NO3- and negative-N* waters were probably generated by mixing between Subantarctic Mode Water from the Southern Ocean and Oxygen Deficit Zone Water from the eastern tropical South Pacific, with remineralization of organic matter occurring during transportation. Moreover, the relationship between δ15N-NO3- and N* values, as well as Trichodesmium abundances and size-specific nitrogen fixation rates at the surface, suggest that the low-δ15N-NO3- and positive-N* subsurface waters between 160°E and 170°W were generated by the input of remineralized particles created by in situ nitrogen fixation, mainly by Trichodesmium spp. Therefore, the δ15N values of sediments in this region are expected to reveal past changes in nitrogen fixation or denitrification rates in the subtropical South Pacific. The copyright line for this article was changed on 5 JUN 2015 after original online publication.

  2. Holocene precipitation in the subtropical Pacific inferred from the carbon isotope composition of Melaleuca quinquenervia (The Broad-leaved Paper Bark tree) leaves

    NASA Astrophysics Data System (ADS)

    Tibby, John; Barr, Cameron; Henderson, Andrew; Leng, Melanie; Marshall, Jon; McGregor, Glenn

    2013-04-01

    Holocene records of the amounts of subtropical precipitation are rare, particularly in the Southern Hemisphere. Yet such information is vital for a comprehensive understanding of global climate system dynamics. We present a precipitation record inferred from the δ13C composition of Melaleuca quinquenervia leaves retrieved from the Holocene sediments of Swallow Lagoon, North Stradbroke Island, in the subtropics of Australia. The modern relationship between rainfall and δ13C was quantified using a collection of monthly leaf falls between 1992 and 2003 and climate data. We then used the calibration to reconstruct precipitation variability from 7500 to 600 cal. yr BP. Dry phases at Swallow Lagoon in the early to mid Holocene are correlated with cooling in the North Atlantic Ocean (i.e. "Bond" events). This relationship breaks down after ~3500 cal. yr BP. From 3500 cal. yr BP there is increased aridity (and variability) associated with the mid- to late Holocene establishment of modern El Niño Southern Oscillation conditions. Overall, these data show linkages between precipitation in the low latitudes of the Southern Hemisphere and Northern Hemisphere cooling events, with a shift to internal forcing of subtropical climate via the Pacific Ocean in the late Holocene.

  3. Impacts of central Pacific and eastern Pacific El Niños on tropical cyclone tracks over the western North Pacific

    NASA Astrophysics Data System (ADS)

    Hong, Chi-Cherng; Li, Yuan-Hsing; Li, Tim; Lee, Ming-Ying

    2011-08-01

    This study examines the different impacts of two types of El Niños, the eastern Pacific El Niño (EP-EN) and the central Pacific El Niño (CP-EN), on tropical cyclone (TC) tracks over the western North Pacific (WNP) based on observational data. Whereas TC tracks between CP-EN and EP-EN show a small difference in boreal summer (JJA), they do exhibit a great difference in boreal autumn (SON), that is, TCs recurve northward at a further westward location near the coastline of East Asia during CP-EN. As a consequence, more TCs make landfall to Taiwan and South China during CP-EN. A further observational analysis indicates that the westward shift of the subtropical high and associated steering flow during CP-EN is a key factor that causes the difference in the TC tracks in autumn. Numerical experiments further suggest that the difference of local SST in the WNP between CP-EN and EP-EN accounts for the distinctive differences in the local Hadley circulation, the subtropical high and the TC steering flow.

  4. 78 FR 18962 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-28

    ... National Oceanic and Atmospheric Administration RIN 0648-XC591 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ACTION: Notice of a public workshop. SUMMARY: The North Pacific Fishery...Wkshop413.pdf . Interested parties also may participate in the workshop via Webex. Details will be posted...

  5. 75 FR 23244 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-03

    ... National Oceanic and Atmospheric Administration RIN 0648-XW17 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ACTION: Notice of a public meeting. SUMMARY: North Pacific Fishery Management Council will host a meeting of the Council Coordination Committee (CCC), consisting of the...

  6. From the subtropics to the equator in the Southwest Pacific: Continental material fluxes quantified using neodymium data along modeled thermocline water pathways

    NASA Astrophysics Data System (ADS)

    Grenier, Mélanie; Jeandel, Catherine; Cravatte, Sophie

    2014-06-01

    The southwestern tropical Pacific, part of a major pathway for waters feeding the Equatorial Undercurrent, is a region of important geochemical enrichment through land-ocean boundary exchange. Here we develop an original method based on the coupling between dynamical modeling and geochemical tracer data to identify regions of enrichment along the water pathways from the subtropics to the equator, and to allow a refined quantification of continental material fluxes. Neodymium data are interpreted with the help of modeled Lagrangian trajectories of an Ocean General Circulation Model. We reveal that upper and lower thermocline waters have different pathways together with different geochemical evolutions. The upper thermocline waters entering the Solomon Sea mainly originate from the central subtropical gyre, enter the Coral Sea in the North Vanuatu Jet and likely receive radiogenic neodymium from the basaltic island margins encountered along their route. The lower thermocline waters entering the Solomon Sea mainly originate from northeast of New Zealand and enter the Coral Sea in the North Caledonian Jet. Depletion of their neodymium content likely occurs when flowing along the Australian and Papua coasts. Downstream from the Solomon Sea, waters flowing along the Papua New Guinea margins near the Sepik river mouth become surprisingly depleted in their neodymium content in the upper thermocline while enriched in the lower thermocline. This coupled approach is proposed as strong support to interpret the origin of the equatorial Pacific natural fertilization through a better understanding of the circulation, important objectives of the international GEOTRACES and SPICE programs, respectively.

  7. Enhanced Late Holocene ENSO/PDO expression along the margins of the eastern North Pacific

    USGS Publications Warehouse

    Barron, J.A.; Anderson, L.

    2011-01-01

    Pacific climate is known to have varied during the Holocene, but spatial patterns remain poorly defined. This paper compiles terrestrial and marine proxy data from sites along the northeastern Pacific margins and proposes that they indicate 1) suppressed ENSO conditions during the middle Holocene between ~8000 and 4000 cal BP with a North Pacific that generally resembled a La Ni??a-like or more negative PDO phase and 2) a climate transition between ~4200 and 3000 cal BP that appears to be the teleconnected expression to a more modern-like ENSO Pacific. Compared to modern day conditions, the compiled data suggest that during the middle Holocene, the Aleutian Low was generally weaker during the winter and/or located more to the west, while the North Pacific High was stronger during the summer and located more to the north. Coastal upwelling off California was more enhanced during the summer and fall but suppressed during the spring. Oregon and California sea surface temperatures (SSTs) were cooler. The Santa Barbara Basin had an anomalous record, suggesting warmer SSTs.Late Holocene records indicate a more variable, El Ni??o-like, and more positive PDO Pacific. The Aleutian Low became more intensified during the winter and/or located more to the east. The North Pacific High became weaker and/or displaced more to the south. Coastal upwelling off California intensified during the spring but decreased during the fall. Oregon and California SSTs became warmer, recording the shoreward migration of sub-tropical gyre waters during the fall, while spring upwelling (cooler SST) increased in the Santa Barbara Basin. The high-resolution proxy records indicate enhanced ENSO and PDO variability after ~4000 cal BP off southern California, ~3400 cal BP off northern California, and by ~2000 cal BP in southwestern Yukon. A progressively northward migration of the ENSO teleconnection during the late Holocene is proposed. ?? 2010.

  8. North and equatorial Pacific Ocean circulation in the CORE-II hindcast simulations

    NASA Astrophysics Data System (ADS)

    Tseng, Yu-heng; Lin, Hongyang; Chen, Han-ching; Thompson, Keith; Bentsen, Mats; Böning, Claus W.; Bozec, Alexandra; Cassou, Christophe; Chassignet, Eric; Chow, Chun Hoe; Danabasoglu, Gokhan; Danilov, Sergey; Farneti, Riccardo; Fogli, Pier Giuseppe; Fujii, Yosuke; Griffies, Stephen M.; Ilicak, Mehmet; Jung, Thomas; Masina, Simona; Navarra, Antonio; Patara, Lavinia; Samuels, Bonita L.; Scheinert, Markus; Sidorenko, Dmitry; Sui, Chung-Hsiung; Tsujino, Hiroyuki; Valcke, Sophie; Voldoire, Aurore; Wang, Qiang; Yeager, Steve G.

    2016-08-01

    We evaluate the mean circulation patterns, water mass distributions, and tropical dynamics of the North and Equatorial Pacific Ocean based on a suite of global ocean-sea ice simulations driven by the CORE-II atmospheric forcing from 1963-2007. The first three moments (mean, standard deviation and skewness) of sea surface height and surface temperature variability are assessed against observations. Large discrepancies are found in the variance and skewness of sea surface height and in the skewness of sea surface temperature. Comparing with the observation, most models underestimate the Kuroshio transport in the Asian Marginal seas due to the missing influence of the unresolved western boundary current and meso-scale eddies. In terms of the Mixed Layer Depths (MLDs) in the North Pacific, the two observed maxima associated with Subtropical Mode Water and Central Mode Water formation coalesce into a large pool of deep MLDs in all participating models, but another local maximum associated with the formation of Eastern Subtropical Mode Water can be found in all models with different magnitudes. The main model bias of deep MLDs results from excessive Subtropical Mode Water formation due to inaccurate representation of the Kuroshio separation and of the associated excessively warm and salty Kuroshio water. Further water mass analysis shows that the North Pacific Intermediate Water can penetrate southward in most models, but its distribution greatly varies among models depending not only on grid resolution and vertical coordinate but also on the model dynamics. All simulations show overall similar large scale tropical current system, but with differences in the structures of the Equatorial Undercurrent. We also confirm the key role of the meridional gradient of the wind stress curl in driving the equatorial transport, leading to a generally weak North Equatorial Counter Current in all models due to inaccurate CORE-II equatorial wind fields. Most models show a larger

  9. Fishery-Induced Changes in the Subtropical Pacific Pelagic Ecosystem Size Structure: Observations and Theory

    PubMed Central

    Polovina, Jeffrey J.; Woodworth-Jefcoats, Phoebe A.

    2013-01-01

    We analyzed a 16-year (1996–2011) time series of catch and effort data for 23 species with mean weights ranging from 0.8 kg to 224 kg, recorded by observers in the Hawaii-based deep-set longline fishery. Over this time period, domestic fishing effort, as numbers of hooks set in the core Hawaii-based fishing ground, has increased fourfold. The standardized aggregated annual catch rate for 9 small (<15 kg) species increased about 25% while for 14 large species (>15 kg) it decreased about 50% over the 16-year period. A size-based ecosystem model for the subtropical Pacific captures this pattern well as a response to increased fishing effort. Further, the model projects a decline in the abundance of fishes larger than 15 kg results in an increase in abundance of animals from 0.1 to 15 kg but with minimal subsequent cascade to sizes smaller than 0.1 kg. These results suggest that size-based predation plays a key role in structuring the subtropical ecosystem. These changes in ecosystem size structure show up in the fishery in various ways. The non-commercial species lancetfish (mean weight 7 kg) has now surpassed the target species, bigeye tuna, as the species with the highest annual catch rate. Based on the increase in snake mackerel (mean weight 0.8 kg) and lancetfish catches, the discards in the fishery are estimated to have increased from 30 to 40% of the total catch. PMID:23620824

  10. Is seasonal net community production in the South Pacific Subtropical Gyre anomalously low?

    NASA Astrophysics Data System (ADS)

    Bender, Michael L.; Jönsson, Bror

    2016-09-01

    The region of the South Pacific Subtropical Gyre (SPSG) at 20°-30°S, 140°-110°W is the oceanic area with the lowest chlorophyll concentration and the deepest nutricline, O2 saturation horizon, and euphotic zone. We analyze the limited available data from this region to determine if rates of net community production (NCP) are systematically lower than elsewhere. We present limited mixed layer O2/Ar data constraining mixed layer NCP, examine hydrographic data from the CLIVAR repeat hydrography P18 line to assess seasonal dissolved inorganic carbon drawdown, and review results from the literature. While it is not possible to formalize uncertainties, the evidence suggests that euphotic zone NCP is around the lower end (~1 mol m-2 yr-1) of rates observed elsewhere. However, NCP is shifted to unusually deep depths, a change enabled by the very low extinction coefficients of these waters.

  11. Oxidation of mercury by bromine in the subtropical Pacific free troposphere

    NASA Astrophysics Data System (ADS)

    Gratz, L. E.; Ambrose, J. L.; Jaffe, D. A.; Shah, V.; Jaeglé, L.; Stutz, J.; Festa, J.; Spolaor, M.; Tsai, C.; Selin, N. E.; Song, S.; Zhou, X.; Weinheimer, A. J.; Knapp, D. J.; Montzka, D. D.; Flocke, F. M.; Campos, T. L.; Apel, E.; Hornbrook, R.; Blake, N. J.; Hall, S.; Tyndall, G. S.; Reeves, M.; Stechman, D.; Stell, M.

    2015-12-01

    Mercury is a global toxin that can be introduced to ecosystems through atmospheric deposition. Mercury oxidation is thought to occur in the free troposphere by bromine radicals, but direct observational evidence for this process is currently unavailable. During the 2013 Nitrogen, Oxidants, Mercury and Aerosol Distributions, Sources and Sinks campaign, we measured enhanced oxidized mercury and bromine monoxide in a free tropospheric air mass over Texas. We use trace gas measurements, air mass back trajectories, and a chemical box model to confirm the origin and chemical history of the sampled air mass. We find the presence of elevated oxidized mercury to be consistent with oxidation of elemental mercury by bromine atoms in this subsiding upper tropospheric air mass within the subtropical Pacific High, where dry atmospheric conditions are conducive to oxidized mercury accumulation. Our results support the role of bromine as the dominant oxidant of mercury in the upper troposphere.

  12. Latitudinal variation in the recruitment dynamics of small pelagic fishes in the western North Pacific

    NASA Astrophysics Data System (ADS)

    Watanabe, Yoshiro

    2007-07-01

    The subarctic Oyashio Current flows south-westward and the subtropical Kuroshio Current flows north-eastward in the western North Pacific, converging in the waters off northern Japan to form the Kuroshio-Oyashio transition region. Some small pelagic fishes inhabit the subarctic or subtropical waters, and others seasonally migrate north and south across the major ocean fronts. Environmental conditions in the subarctic and transition waters are variable, whereas in the subtropical Kuroshio waters conditions are relatively stable. Latitudinally different environmental conditions may affect vital parameters and recruitment variability of small pelagic fishes inhabiting the various waters. Pacific saury Cololabis saira migrate seasonally from the Kuroshio to Oyashio waters and spawn in the transition waters in autumn and spring and in the Kuroshio waters in winter. During 1990-1999, the coefficients of variation (CVs) of daily growth rates (G) and instantaneous mortality coefficients (M) were large for larvae and juveniles spawned in the northern transition waters, but relatively small for those from the southern Kuroshio waters. The Pacific stock of chub mackerel Scomber japonicus spawns in the Kuroshio waters in spring and early summer and migrates to the subarctic Oyashio waters in summer for feeding, whereas the Tsushima Warm Current stock spawns in the East China Sea in spring and fish remain in the subtropical warm waters throughout their lifetime. The Pacific stock had CVs > 100% for the fish aged 0-5 during 1970-2002. In contrast, the Tsushima Warm Current stock had CVs of 34-40% during 1973-2002. Pacific herring Clupea pallasii, which inhabits subarctic waters, had CVs of 118-178% for the fish aged 3-8 y during 1910-1954. Japanese sardine Sardinops melanostictus, which spawn in the subtropical Kuroshio waters and migrate to the subarctic Oyashio waters in summer for feeding, had CVs > 120% for the fish aged 0-4 during 1976-2003. Contrasting with these subarctic

  13. Atmospheric Mercury Deposition to a Remote Islet in the Subtropical Northwest Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Sheu, G.; Lin, N.

    2013-12-01

    Thirty-four weekly rainwater samples were collected in 2009 at Pengjiayu, a remote islet in the subtropical Northwest (NW) Pacific Ocean with an area of 1.14 km^2, to study the distribution of rainwater mercury (Hg) concentrations and associated wet deposition fluxes. This is the first study concerning wet Hg deposition to the subtropical NW Pacific Ocean downwind of the East Asian continent, which is the major source region for Hg emissions worldwide. Sample Hg concentrations ranged from 2.25 to 22.33 ng L^-1, with a volume-weighted mean (VWM) concentration of 8.85 ng L^-1. The annual wet Hg deposition flux was 10.18 μg m^-2, about 2.5 times the fluxes measured at sites on the Pacific coast of the USA, supporting the hypothesis that deposition is higher in the western than in the eastern Pacific. Seasonal VWM concentrations were 7.23, 11.58, 7.82, and 9.84 ng L^-1, whereas seasonal wet deposition fluxes were 2.14, 3.45, 2.38, and 2.21 μg m^-2, for spring, summer, fall and winter, respectively. Higher summer wet Hg deposition was a function of both higher rainwater Hg concentration and greater rainfall. The seasonal pattern of rainwater Hg concentrations was the opposite of the general seasonal pattern of the East Asian air pollutant export. Since there is no significant anthropogenic Hg emission source on the islet of Pengjiayu, the observed high summertime rainwater Hg concentration hints at the importance of Hg(0) oxidation and/or scavenging of upper-altitude reactive gaseous Hg (RGM) by deep convection. Direct anthropogenic RGM emissions from the East Asian continent may not contribute significantly to the rainwater Hg concentrations, but anthropogenic Hg(0) emissions could be transported to the upper troposphere or marine boundary layer where they can be oxidized to produce RGM, which will then be effectively scavenged by cloud water and rainwater.

  14. Possible influence of western North Pacific monsoon on TC activity in mid-latitudes of East Asia

    NASA Astrophysics Data System (ADS)

    Choi, Ki-Seon; Cha, Yumi; Kim, Hae-Dong; Kang, Sung-Dae

    2016-01-01

    This study analyzed the correlation between tropical cyclone (TC) frequency and the Western North Pacific monsoon index (WNPMI), which have both been influential in East Asia's mid-latitude regions during the summer season over the past 37 years (1977-2013). A high positive correlation existed between these two variables, which was not reduced even if El Niño-Southern Oscillation (ENSO) years were excluded. To determine the cause of this positive correlation, the highest (positive WNPMI phase) and lowest WNPMIs (negative WNPMI phase) during a nine-year period were selected to analyze the mean difference between them, excluding ENSO years. In the positive WNPMI phase, TCs were mainly generated in the eastern seas of the tropical and subtropical western North Pacific, passing through the East China Sea and moving northward toward Korea and Japan. In the negative phase, TCs were mainly generated in the western seas of the tropical and subtropical western North Pacific, passing through the South China Sea and moving westward toward China's southern regions. Therefore, TC intensity in the positive phase was stronger due to the acquisition of sufficient energy from the sea while moving a long distance up to East Asia's mid-latitude. Additionally, TCs occurred more in the positive phase. Regarding the difference of the two phases between the 850 and 500-hPa streamlines, anomalous cyclones were strengthened in the tropical and subtropical western North Pacific, whereas anomalous anticyclones were strengthened in East Asia's mid-latitude regions. Due to these two anomalous pressure systems, anomalous southeasterlies developed in East Asia's mid-latitude regions, which played a role in the anomalous steering flows that moved TCs into these regions. Furthermore, due to the anomalous cyclones that developed in the tropical and subtropical western North Pacific, more TCs could be generated in the positive phase. Both the lower and upper tropospheric layers had warm anomalies

  15. Ventilation time scales of the North Atlantic subtropical cell revealed by coral radiocarbon from the Cape Verde Islands

    NASA Astrophysics Data System (ADS)

    Fernandez, Alvaro; Lapen, Thomas J.; Andreasen, Rasmus; Swart, Peter K.; White, Christopher D.; Rosenheim, Brad E.

    2015-07-01

    We present coral- and sclerosponge-based reconstructions of the 14C content in North Atlantic dissolved inorganic carbon (DIC) during the last ~100 years from the subtropical cells (STCs). These waters are sensitive to the dynamics of the shallow overturning meridional circulation that transports heat and water masses from the subtropics to the tropics. We use these records to investigate the circulation patterns of the off-equatorial upwelling regions of the STCs, which are not well understood. Coral and sclerosponge skeletons provide long time series of ocean DIC 14C content, a tracer of oceanic circulation, effectively extending the observational record back in time. Sclerosponge data from the Bahamas were used to extend the existing subtropical 14C time series to the 21st century. Coral 14C data from the Cape Verde Islands (1890-2002) captured the 14C signature of water brought to the surface in the off-equatorial regions of the STC present near the West African coast. We observe a unique postbomb trend at Cape Verde that is similar to the upwelling regions in the Pacific, and we interpret this trend as the result of the slow penetration of bomb 14C into the interior ocean as part of the STC circulation. Using a multibox mixing model we constrain the time history of bomb 14C in the eastern tropical Atlantic, and we estimate a 20 year time scale for ventilation of the thermocline in this area of the ocean. The similarity between the Atlantic and Pacific 14C-based records of upwelling suggests that both are caused by bomb 14C penetration rather than more complex explanations that invoke changes in thermocline depth (e.g., related to El Niño-Southern Oscillation variability) or changes in the strength of the subtropical cells. Our results offer constraints for models of tropical ocean circulation and anthropogenic CO2 uptake that attempt to reproduce the characteristics of the shallow wind-driven circulation in the Atlantic.

  16. Evidence for production and lateral transport of dissolved organic phosphorus in the eastern subtropical North Atlantic

    NASA Astrophysics Data System (ADS)

    Reynolds, Sarah; Mahaffey, Claire; Roussenov, Vassil; Williams, Richard G.

    2014-08-01

    The concentration of phosphate and dissolved organic phosphorus (DOP) is chronically low and limits phytoplankton growth in the subtropical North Atlantic relative to other ocean basins. Transport of phosphate and DOP from the productive flanks of the gyre to its interior has been hypothesized as an important phosphorus supply pathway. During a cruise in the eastern Atlantic in spring 2011, the rates of phosphate uptake, alkaline phosphatase activity (APA), and DOP production were measured in the northwest African shelf region, subtropics, and tropics. Rates of DOP production were sixfold higher in the shelf region (43 ± 41 nM d-1) relative to the subtropics (6.9 ± 4.4 nM d-1). In contrast, APA was threefold higher in the subtropics (8.0 ± 7.3 nM d-1), indicative of enhanced DOP utilization, relative to the shelf region (2.6 ± 2.1 nM d-1). Hence, observations suggest net production of DOP in the shelf region and either net consumption of DOP or a near balance in DOP production and consumption in the gyre interior. Eddy-permitting model experiments demonstrate that (i) DOP accounts for over half the total phosphorus in surface waters, (ii) DOP is transported westward from the shelf region by a combination of gyre and eddy circulations, and (iii) advected DOP supports up to 70% of the particle export over much of the subtropical gyre. Our combined observational and modeling study supports the view that the horizontal transport of DOP from the shelf region is an important mechanism supplying phosphorus to the surface subtropical North Atlantic.

  17. A decadal precession of atmospheric pressures over the North Pacific

    NASA Astrophysics Data System (ADS)

    Anderson, Bruce T.; Gianotti, Daniel J. S.; Furtado, Jason C.; Di Lorenzo, Emanuele

    2016-04-01

    Sustained droughts over the Northwestern U.S. can alter water availability to the region's agricultural, hydroelectric, and ecosystem service sectors. Here we analyze decadal variations in precipitation across this region and reveal their relation to the slow (~10 year) progression of an atmospheric pressure pattern around the North Pacific, which we term the Pacific Decadal Precession (PDP). Observations corroborate that leading patterns of atmospheric pressure variability over the North Pacific evolve in a manner consistent with the PDP and manifest as different phases in its evolution. Further analysis of the data indicates that low-frequency fluctuations of the tropical Pacific Ocean state energize one phase of the PDP and possibly the other through coupling with the polar stratosphere. Evidence that many recent climate variations influencing the North Pacific/North American sector over the last few years are consistent with the current phase of the PDP confirms the need to enhance our predictive understanding of its behavior.

  18. Will the western Pacific subtropical high constantly intensify in the future?

    NASA Astrophysics Data System (ADS)

    Huang, Yanyan; Li, Xiaofan; Wang, Huijun

    2016-07-01

    The western Pacific subtropical high (WPSH) features lower-level southerlies or southwesterlies at its western and southern edges that transport amount of water vapor into East Asia, and it exerts a large influence on the East Asian summer climate. This paper evaluates the historical (1950-2005) spatial distribution and variability in the summer WPSH at 850 hPa using 28 general circulation models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) relative to the NCEP-NCAR reanalysis data. To avoid the artificial influence caused by global warming, this study primarily investigates the 850-hPa eddy geopotential height and the horizontal winds. The results show that most of the CMIP5 models reliably reproduce the geographical distribution and spatial variability in the WPSH. Four models (bcc-csm1-1, CESM1-CAM5, GFDL-ESM2G and inmcm4) generally perform well in simulating the eastward-recessed interdecadal variation in the WPSH during 1979-2005 relative to 1950-1978, with a significant cyclone anomaly appearing over the western Pacific and a decreasing trend in the WPSH index. Based on these four models, a multi-model ensemble projects a weaker WPSH during 2026-2070 relative to 2010-2025 and 2071-2100 under the representative concentration pathway 8.5 scenario.

  19. The response of winter Pacific North American pattern to strong volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Liu, Zhongfang; Yoshimura, Kei; Buenning, Nikolaus H.; Jian, Zhimin; Zhao, Liang

    2016-07-01

    The impact of volcanic eruptions on large-scale atmospheric circulation patterns has been well studied, but very little effort has been made on relating the response of Pacific North American (PNA) pattern to strong volcanic eruptions. Here we investigate the response of winter PNA to the largest volcanic eruptions using three different reanalysis datasets. We demonstrate a significant positive PNA circulation response to strong volcanic forcing in the first winter following the eruptions. This circulation pattern is associated with enhanced southwesterly winds advecting warm air from the tropical/subtropical Pacific into northwestern North America and leads to a significant warming in the region. However, no significant PNA signal is found for the second post-eruption winter. The PNA responses to volcanic forcing depend partly upon the modulation of the El Niño Southern Oscillation (ENSO) events. When the ENSO influence is linearly removed, this positive PNA signal is still robust during the first post-eruption winter, albeit with slightly decreased magnitude and significance. Our findings provide new evidence for volcanic forcing of the Pacific and North American climates. The results presented here may contribute to deconvolving modern and past continental-scale climate changes over North America.

  20. Sea-air of CO2 in the North Pacific using shipboard and satellite data

    NASA Technical Reports Server (NTRS)

    Stephens, Mark P.; Samuels, Geoffrey; Olson, Donald B.; Fine, Rana A.; Takahashi, Taro

    1995-01-01

    A method has been developed to produce high-resolution maps of pCO2 in surface water for the North Pacific using satellite sea surface temperature (SST) data and statistical relationships between measured pCO2 and temperature. In the subtropical North Pacific the pCO in seawater is controlled primarily by temperature. Accordingly, pCO2 values that are calculated from the satellite SST data have good agreement with the measured values (rms deviation of +/- microatm). In the northwestern subpolar region the pCO2 is controlled not only by temperature, but also by significant seasonal changes in the total CO2 concentration, which are caused by seasonal changes in primary production, mixing with subsurface waters and sea-air exchange. Consequently, the parameterization of oceanic p CO2 based on SST data alone is not totally successful in the northwestern region (rms deviation of +/- 40 microatm). The use of additional satellite products, such as wind and ocean color data, as planned for a future study, is considered necessary to account for the pCO2 variability caused by seasonal changes in the total CO2 concentration. The net CO2 flux for the area of the North Pacific included in this study (north of 10 deg N) has been calculated using the monthly pCO2 distributions computed, and monthly wind speeds from the European Centre for Medium-Range Weather Forecasts. The region is found to be a net source to the atmosphere of 1.9 x 10(exp 12) to 5.8 x 10(exp 12) moles of CO2 per year (or 0.02-0.07 Gt C/yr), most of the outflux occurring in the subtropics.

  1. What maintains the central North Pacific genetic discontinuity in Pacific herring?

    PubMed

    Liu, Ming; Lin, Longshan; Gao, Tianxiang; Yanagimoto, Takashi; Sakurai, Yasunori; Grant, W Stewart

    2012-01-01

    Pacific herring show an abrupt genetic discontinuity in the central North Pacific that represents secondary contact between refuge populations previously isolated during Pleistocene glaciations. Paradoxically, high levels of gene flow produce genetic homogeneity among ocean-type populations within each group. Here, we surveyed variability in mtDNA control-region sequences (463 bp) and nine microsatellite loci in Pacific herring from sites across the North Pacific to further explore the nature of the genetic discontinuity around the Alaska Peninsula. Consistent with previous studies, little divergence (Φ(ST)  = 0.011) was detected between ocean-type populations of Pacific herring in the North West Pacific, except for a population in the Yellow Sea (Φ(ST)  = 0.065). A moderate reduction in genetic diversity for both mtDNA and microsatellites in the Yellow Sea likely reflects founder effects during the last colonization of this sea. Reciprocal monophyly between divergent mtDNA lineages (Φ(ST)  = 0.391) across the Alaska Peninsula defines the discontinuity across the North Pacific. However, microsatellites did not show a strong break, as eastern Bering Sea (EBS) herring were more closely related to NE Pacific than to NW Pacific herring. This discordance between mtDNA and microsatellites may be due to microsatellite allelic convergence or to sex-biased dispersal across the secondary contact zone. The sharp discontinuity between Pacific herring populations may be maintained by high-density blocking, competitive exclusion or hybrid inferiority.

  2. Impact of effective ocean optical properties on the Pacific subtropical cell: a CGCM study

    NASA Astrophysics Data System (ADS)

    Yamanaka, G.; Tsujino, H.; Ishizaki, H.; Nakano, H.; Hirabara, M.

    2012-12-01

    The choice of ocean radiant scheme is important for modeling the upper ocean. According to the ocean-only simulation (Yamanaka et al., 2012), introduction of the chlorophyll-a dependent ocean radiant scheme results in the decreased mixed layer depth (MLD), the enhanced subtropical cell (STC), and the cooling of the eastern tropical Pacific sea surface temperature (SST). They also found that the enhanced STC results from the velocity profile change associated with the decreased Ekman boundary layer. However, the impact is not well understood when the air-sea feedback process is at work. This study examines the impact of the effective ocean optical properties on the Pacific mean fields, especially focusing on the STC, using a coupled general circulation model (CGCM). The CGCM we employed is the Meteorological Research Institute Earth System Model (MRI-ESM1). The atmospheric model is TL159L48, and the ocean model has a horizontal resolution of 1 x 0.5 deg. with 51 levels in vertical. Experimental design basically follows the CMIP5 protocol. Two experiments (CTL and SLR runs) are performed to investigate the impact of the effective ocean optical properties. In the CTL run, a conventional ocean radiant heating scheme (Paul and Simpson, 1977) is used, whereas a new ocean radiant heating scheme is used in the SLR run, where the satellite-derived chlorophyll-a distribution is taken into consideration based on Morel and Antoine (1994) as well as the effect of the varying solar angle (Ishizaki and Yamanaka, 2010). Each experiment is integrated during the period from 1985 to 2005. It is found that introduction of the new ocean radiant scheme (SLR run) changes the long-term mean wind pattern in the Pacific: easterly winds are strengthened in the equatorial Pacific, but weakened in the off-equatorial region. In the tropical Pacific, the enhanced equatorial upwelling cools the equatorial SST and the MLD becomes shallower. This is similar to the ocean-only simulation, but is more

  3. Temperature-dependence of planktonic metabolism in the Subtropical North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    García-Corral, L. S.; Barber, E.; Regaudie-de-Gioux, A.; Sal, S.; Holding, J.; Agustí, S.; Navarro, N.; Serret, P.; Mozetič, P.; Duarte, C. M.

    2014-02-01

    The temperature dependence of planktonic metabolism in the Subtropical North Atlantic Ocean was assessed on the basis of measurements of gross primary production (GPP), community respiration (CR) and net community production (NCP), as well as experimental assessments of the response of CR to temperature manipulations. Metabolic rates were measured at 68 stations along three consecutive longitudinal transects completed during the Malaspina 2010 Expedition, in three different seasons. Temperatures gradients were observed in depth and at basin and seasonal scale. The results showed seasonal variability in the metabolic rates, being the highest rates observed during the spring transect. The overall mean integrated GPP/CR ratio was of 1.39 ± 0.27 decreasing from winter to summer and the NCP for the Subtropical North Atlantic Ocean during this cruises, was net autotrophy (NCP > 0) in about two-thirds of the total sampled communities (68.2%). Here, we reported the activation energies describing the temperature-dependence of planktonic community metabolism, which generally was higher for CR than for GPP in the Subtropical North Atlantic Ocean, as the metabolic theory of ecology predicts. Also, we performed an assessment of the activation energies describing the responses to in situ temperature at field (EaCR = 1.64 ± 0.36 eV) and those derive experimentally by temperature manipulations (EaCR = 1.45 ± 0.6 eV), which showed a great consistency.

  4. Reconstruction of the springtime East Asian Subtropical Jet and Western Pacific pattern from a millennial-length Taiwanese tree-ring chronology

    NASA Astrophysics Data System (ADS)

    Wright, W. E.; Guan, B. T.; Tseng, Y.-H.; Cook, E. R.; Wei, K.-Y.; Chang, S.-T.

    2015-03-01

    The East Asian subtropical jet (EAJ) and the closely related Western Pacific pattern (WP) are among the most important features in global atmospheric dynamics, but little is known about their long-term variability. This study presents reconstructions of the Spring EAJ index (EAJI) and the Spring WP index (WPI) based on significant relationships identified between mean values for these features and a millennial length tree-ring width chronology of Chamaecyparis obtusa var. formosana, a high-mountain cloud forest species from northeastern Taiwan. Tree-ring based reconstructions of high pass filtered versions of the EAJI and WPI (EAJI 5YR and WPI 5YR) presented herein explain 42 and 31 % of the WPI 5YR and EAJI 5YR, respectively, and display acceptable reliability back to A.D. 1237. A significant trend present in the long-term variance of the reconstructed EAJI and WPI after A.D. 1860 suggests long-term increasing variability in the spring mean latitudinal placement and/or the strength/breadth of the EAJ core region near Taiwan and Japan and in the trajectory of the EAJ over the North Pacific. Related features affected by changes in the EAJ include the North Pacific storm track and Asian Dust transport.

  5. Clustering analysis of western North Pacific Tropical Cyclone tracks using the Self Organizing Map

    NASA Astrophysics Data System (ADS)

    Kim, H.; Seo, K.

    2013-12-01

    A cluster analysis using Self Organizing Map (SOM) is used to characterize tropical cyclone (TC) tracks over the western North Pacific. A False Discovery Rate (FDR) method is used to objectively determine an optimum cluster number. For 620 TC tracks over the WNP from June-October during 1979-2010, the five clusters for TC tracks are selected. These can further be categorized into three major patterns: straight-moving track, recurving track, and quasi-random pattern. Each pattern is characterized by land falling regions: near South and East China, East Asia, and off-shore of Japan. In addition, each pattern shows distinctive properties in its traveling distance, lifetime, intensity (mean minimum sea level pressure), and genesis location. It is revealed that these three patterns are associated with the large-scale dynamics such as variability of the western Pacific subtropical high and the Madden-Julian Oscillation. The impacts of El Nino and NAO will be discussed.

  6. Enhanced Late Holocene ENSO/PDO expression along the margins of the eastern North Pacific

    USGS Publications Warehouse

    Barron, John A.; Anderson, Lesleigh

    2011-01-01

    Late Holocene records indicate a more variable, El Niño-like, and more positive PDO Pacific. The Aleutian Low became more intensified during the winter and/or located more to the east. The North Pacific High became weaker and/or displaced more to the south. Coastal upwelling off California intensified during the spring but decreased during the fall. Oregon and California SSTs became warmer, recording the shoreward migration of sub-tropical gyre waters during the fall, while spring upwelling (cooler SST) increased in the Santa Barbara Basin. The high-resolution proxy records indicate enhanced ENSO and PDO variability after ∼4000 cal BP off southern California, ∼3400 cal BP off northern California, and by ∼2000 cal BP in southwestern Yukon. A progressively northward migration of the ENSO teleconnection during the late Holocene is proposed.

  7. Communicating Volcanic Hazards in the North Pacific

    NASA Astrophysics Data System (ADS)

    Dehn, J.; Webley, P.; Cunningham, K. W.

    2014-12-01

    For over 25 years, effective hazard communication has been key to effective mitigation of volcanic hazards in the North Pacific. These hazards are omnipresent, with a large event happening in Alaska every few years to a decade, though in many cases can happen with little or no warning (e.g. Kasatochi and Okmok in 2008). Here a useful hazard mitigation strategy has been built on (1) a large database of historic activity from many datasets, (2) an operational alert system with graduated levels of concern, (3) scenario planning, and (4) routine checks and communication with emergency managers and the public. These baseline efforts are then enhanced in the time of crisis with coordinated talking points, targeted studies and public outreach. Scientists naturally tend to target other scientists as their audience, whereas in effective monitoring of hazards that may only occur on year to decadal timescales, details can distract from the essentially important information. Creating talking points and practice in public communications can help make hazard response a part of the culture. Promoting situational awareness and familiarity can relieve indecision and concerns at the time of a crisis.

  8. 75 FR 53951 - North Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-02

    ... Council;s Gulf of Alaska (GOA) and Bering Sea/Aleutian Islands (BS/AI) Groundfish Plan Teams will meet in... (GOA Plan Team) and Traynor Room (BS/AI Plan Team), Seattle, WA. Council address: North Pacific...

  9. Along-isopycnal variability of spice in the North Pacific

    NASA Astrophysics Data System (ADS)

    Klymak, Jody M.; Crawford, William; Alford, Matthew H.; MacKinnon, Jennifer A.; Pinkel, Robert

    2015-03-01

    Two hydrographic surveys in the Gulf of Alaska and the North Pacific subtropical gyre are presented. Both surveys are roughly perpendicular to lateral temperature gradients, and were collected in the summer when there was a shallow mixed layer and a seasonal thermocline. Isopycnal displacements and horizontal velocities are dominated by internal waves. Spice anomalies along isopycnals are examined to diagnose lateral stirring mechanisms. The spectra of spice anomaly gradients along near-surface isopycnals roughly follow power laws of ˜kx0.6±0.2 (variance spectra power laws of ˜kx-1.4±0.2), and in most cases, the spectra become redder at depth. The near-surface spectra are possibly consistent with the predictions of quasi-geostrophic turbulence theory (when surface buoyancy effects are accounted for), but the spectra at depth are inconsistent with any quasi-geostrophic theory. Probability distributions of spice gradients exhibit a large peak at low gradients and long tails for large gradients, symptomatic of fronts. Vertical coherence of the spice signal falls off with a decorrelation depth scale that has a maximum of about 80 m at 100 km wavelengths and depends on horizontal wavelength with a power law of approximately kx-1/2. Lateral decorrelation length scales are 20-40 km, close to the baroclinic Rossby radius. Lateral stirring occurs over large scales, with average lateral displacements of about 200 km in the upper 75 m, decreasing to 100 km at greater depths. The depth variation of the statistics indicates that time history of tracer stirring on each isopycnal is important, or that there are unconsidered depth-dependent stirring mechanisms.

  10. Effects of tropical North Atlantic SST on tropical cyclone genesis in the western North Pacific

    NASA Astrophysics Data System (ADS)

    Yu, Jinhua; Li, Tim; Tan, Zhemin; Zhu, Zhiwei

    2016-02-01

    The tropical cyclone genesis number (TCGN) in July-October (JASO) over the western North Pacific (WNP) exhibits a robust interannual variation. It shows a longitudinally tri-pole pattern with a high in the eastern WNP and South China Sea (SCS) and a low in the western WNP, which explain 42.2 and 23.4 % of total TCGN variance in the eastern WNP and SCS, respectively. The high-low-high pattern is similar to that derived from a TC genesis potential index (GPI). To understand the cause of the longitudinal distribution of the dominant interannual mode, we examine the contributions of environmental parameters associated with GPI. It is found that relative humidity and relative vorticity are important factors responsible for TC variability in the SCS, while vertical shear and relative vorticity are crucial in determining TC activity in eastern WNP. A simultaneous correlation analysis shows that the WNP TCGN in JASO is significantly negatively correlated (with a correlation coefficient of -0.5) with sea surface temperature anomalies (SSTA) in the tropical North Atlantic (TNA). The longitudinal distribution of TC genesis frequency regressed onto TNA SSTA resembles that regressed upon the WNP TCGN series. The spatial patterns of regressed environmental variables onto the SSTA over the TNA also resemble those onto TCGN in the WNP, that is, an increase of relative humidity in the SCS and a weakening of vertical shear in the eastern WNP are all associated with cold SSTA in the TNA. Further analyses show that the cold SSTA in the TNA induce a negative heating in situ. In response to this negative heating, a low (upper)-level anomalous aniti-cyclonic (cyclonic) flows appear over the subtropical North Atlantic and eastern North Pacific, and to east of the cold SSTA, anomalous low-level westerlies appear in the tropical Indian Ocean. Given pronounced mean westerlies in northern Indian Ocean in boreal summer, the anomalous westerly flows increase local surface wind speed and surface

  11. NORTH PACIFIC SALMON MONITORING WORKSHOP I - SUMMARY REPORT

    EPA Science Inventory

    The intent of the first North Pacific Salmon Monitoring Workshop was to initiate development of an economically feasible monitoring strategy that could serve as a warning system for detecting changes in the status of Pacific Rim salmon. This is a summary of the workshop held Fe...

  12. Prediction of dominant intraseasonal modes in the East Asian-western North Pacific summer monsoon

    NASA Astrophysics Data System (ADS)

    Oh, Hyoeun; Ha, Kyung-Ja

    2016-10-01

    Intraseasonal monsoon prediction is the most imperative task, but there remains an enduring challenge in climate science. The present study aims to provide a physical understanding of the sources for prediction of dominant intraseasonal modes in the East Asian-western North Pacific summer monsoon (EA-WNPSM): pre-Meiyu&Baiu, Changma&Meiyu, WNPSM, and monsoon gyre modes classified by the self-organizing map analysis. Here, we use stepwise regression to determine the predictors for the four modes in the EA-WNPSM. The selected predictors are based on the persistent and tendency signals of the sea surface temperature (SST)/2m air temperature and sea level pressure fields, which reflect the asymmetric response to the El Niño Southern Oscillation (ENSO) and the ocean and land surface anomalous conditions. For the pre-Meiyu&Baiu mode, the SST cooling tendency over the western North Pacific (WNP), which persists into summer, is the distinguishing contributor that results in strong baroclinic instability. A major precursor for the Changma&Meiyu mode is related to the WNP subtropical high, induced by the persistent SST difference between the Indian Ocean and the western Pacific. The WNPSM mode is mostly affected by the Pacific-Japan pattern, and monsoon gyre mode is primarily associated with a persistent SST cooling over the tropical Indian Ocean by the preceding ENSO signal. This study carries important implications for prediction by establishing valuable precursors of the four modes including nonlinear characteristics.

  13. Prediction of dominant intraseasonal modes in the East Asian-western North Pacific summer monsoon

    NASA Astrophysics Data System (ADS)

    Oh, Hyoeun; Ha, Kyung-Ja

    2015-12-01

    Intraseasonal monsoon prediction is the most imperative task, but there remains an enduring challenge in climate science. The present study aims to provide a physical understanding of the sources for prediction of dominant intraseasonal modes in the East Asian-western North Pacific summer monsoon (EA-WNPSM): pre-Meiyu&Baiu, Changma&Meiyu, WNPSM, and monsoon gyre modes classified by the self-organizing map analysis. Here, we use stepwise regression to determine the predictors for the four modes in the EA-WNPSM. The selected predictors are based on the persistent and tendency signals of the sea surface temperature (SST)/2m air temperature and sea level pressure fields, which reflect the asymmetric response to the El Niño Southern Oscillation (ENSO) and the ocean and land surface anomalous conditions. For the pre-Meiyu&Baiu mode, the SST cooling tendency over the western North Pacific (WNP), which persists into summer, is the distinguishing contributor that results in strong baroclinic instability. A major precursor for the Changma&Meiyu mode is related to the WNP subtropical high, induced by the persistent SST difference between the Indian Ocean and the western Pacific. The WNPSM mode is mostly affected by the Pacific-Japan pattern, and monsoon gyre mode is primarily associated with a persistent SST cooling over the tropical Indian Ocean by the preceding ENSO signal. This study carries important implications for prediction by establishing valuable precursors of the four modes including nonlinear characteristics.

  14. Abyssal echinoid and asteroid fauna of the North Pacific

    NASA Astrophysics Data System (ADS)

    Mironov, A. N.; Minin, K. V.; Dilman, A. B.

    2015-01-01

    Echinoidea and Asteroidea collected in the Kuril-Kamchatka Trench area by the KuramBio Expedition were examined. Altogether 20 species belonging to 16 genera were found, among them six species and two genera were recorded in the North Pacific for the first time. Morphological variability of Abyssaster tara suggests that this species is congeneric with Styracaster transitivus and Styracaster paucispinus. Complete age series of the echinoid Echinosigra amphora and the asteroid Eremicaster crassus are described. The juveniles of E. amphora (>0.5 mm in length) are characterized by unique ophicephalous pedicellaria in the centre of aboral side of the test. The abyssal echinoid and asteroid fauna of the North Pacific (north of 30°N and deeper than 3000 m) comprises 62 species of 36 genera; 22 species (35%) and 3 genera are endemic to this region. Global distribution patterns of genera support the hypothesis that there were two stages of dispersal from the Antarctic to the North Pacific: at earlier stage the dispersal occurred via the East Pacific and at the later stage - via the West Pacific. The genera that had dispersed at earlier stage are represented only in the North and East Pacific and Antarctic. Distribution ranges of these genera in the East Pacific are limited to the narrow zone extending meridionally along the base of the American continental slope. Genera with such distribution pattern are likely adapted to highly eutrophic conditions.

  15. Intrusion of Fukushima-derived radiocaesium into subsurface water due to formation of mode waters in the North Pacific

    PubMed Central

    Kaeriyama, Hideki; Shimizu, Yugo; Setou, Takashi; Kumamoto, Yuichiro; Okazaki, Makoto; Ambe, Daisuke; Ono, Tsuneo

    2016-01-01

    The Fukushima Dai-ichi Nuclear Power Plant accident in March 2011 released radiocaesium (137Cs and 134Cs) into the North Pacific Ocean. Meridional transects of the vertical distribution of radiocaesium in seawater were measured along 147 °E and 155 °E in October–November 2012, 19 months after the accident. These measurements revealed subsurface peaks in radiocaesium concentrations at locations corresponding to two mode waters, Subtropical Mode Water and Central Mode Water. Mode water is a layer of almost vertically homogeneous water found over a large geographical area. Here we show that repeated formation of mode water during the two winter seasons after the Fukushima accident and subsequent outcropping into surface water transported radiocaesium downward and southward to subtropical regions of the North Pacific. The total amount of Fukushima-derived 134Cs within Subtropical Mode Water, decay-corrected to April 2011, was estimated to be 4.2 ± 1.1 PBq in October–November 2012. This amount of 134Cs corresponds to 22–28% of the total amount of 134Cs released to the Pacific Ocean. PMID:26915424

  16. Intrusion of Fukushima-derived radiocaesium into subsurface water due to formation of mode waters in the North Pacific

    NASA Astrophysics Data System (ADS)

    Kaeriyama, Hideki; Shimizu, Yugo; Setou, Takashi; Kumamoto, Yuichiro; Okazaki, Makoto; Ambe, Daisuke; Ono, Tsuneo

    2016-02-01

    The Fukushima Dai-ichi Nuclear Power Plant accident in March 2011 released radiocaesium (137Cs and 134Cs) into the North Pacific Ocean. Meridional transects of the vertical distribution of radiocaesium in seawater were measured along 147 °E and 155 °E in October–November 2012, 19 months after the accident. These measurements revealed subsurface peaks in radiocaesium concentrations at locations corresponding to two mode waters, Subtropical Mode Water and Central Mode Water. Mode water is a layer of almost vertically homogeneous water found over a large geographical area. Here we show that repeated formation of mode water during the two winter seasons after the Fukushima accident and subsequent outcropping into surface water transported radiocaesium downward and southward to subtropical regions of the North Pacific. The total amount of Fukushima-derived 134Cs within Subtropical Mode Water, decay-corrected to April 2011, was estimated to be 4.2 ± 1.1 PBq in October–November 2012. This amount of 134Cs corresponds to 22–28% of the total amount of 134Cs released to the Pacific Ocean.

  17. Intrusion of Fukushima-derived radiocaesium into subsurface water due to formation of mode waters in the North Pacific.

    PubMed

    Kaeriyama, Hideki; Shimizu, Yugo; Setou, Takashi; Kumamoto, Yuichiro; Okazaki, Makoto; Ambe, Daisuke; Ono, Tsuneo

    2016-02-26

    The Fukushima Dai-ichi Nuclear Power Plant accident in March 2011 released radiocaesium ((137)Cs and (134)Cs) into the North Pacific Ocean. Meridional transects of the vertical distribution of radiocaesium in seawater were measured along 147 °E and 155 °E in October-November 2012, 19 months after the accident. These measurements revealed subsurface peaks in radiocaesium concentrations at locations corresponding to two mode waters, Subtropical Mode Water and Central Mode Water. Mode water is a layer of almost vertically homogeneous water found over a large geographical area. Here we show that repeated formation of mode water during the two winter seasons after the Fukushima accident and subsequent outcropping into surface water transported radiocaesium downward and southward to subtropical regions of the North Pacific. The total amount of Fukushima-derived (134)Cs within Subtropical Mode Water, decay-corrected to April 2011, was estimated to be 4.2 ± 1.1 PBq in October-November 2012. This amount of (134)Cs corresponds to 22-28% of the total amount of (134)Cs released to the Pacific Ocean.

  18. Peat Formation on Minjerribah (North Stradbroke Island), subtropical eastern Australia

    NASA Astrophysics Data System (ADS)

    Moss, Patrick; Tibby, John; Barr, Cameron; Weerensena, Chagi; Gontz, Allen; Petherick, Lynda

    2016-04-01

    Minjerribah (North Stradbroke Island) is the second largest sand island in the world and contains extensive peat dominated wetlands, comprising ~20% of the total area of the island. These wetland systems include large areas of estuarine swamps [mainly mangrove forest (~16% of the island's wetland area)], freshwater swamps [both herb (~58% of the island's wetland area) and tree dominated (~20% of the island's wetland area)] and numerous lake systems [both perched and window lakes (~2% of the island's wetland area)]. This presentation will examine peat formation processes at four wetland sites: a late Holocene prograding beach system (Flinders Beach); a 150,000 year lacustrine system (Welsby Lagoon 1), as well as a late Holocene lacustrine/palustrine system (Welsby Lagoon 2); and a late Quaternary lacustrine/palustrine system (Tortoise Lagoon), as well as discussing broader environmental characteristics of Minjerribah's nationally and internationally important wetland systems.

  19. Radiostrontium in the western North Pacific: characteristics, behavior, and the Fukushima impact.

    PubMed

    Povinec, Pavel P; Hirose, Katsumi; Aoyama, Michio

    2012-09-18

    The impact of the Fukushima-derived radiostrontium ((90)Sr and (89)Sr) on the western North Pacific Ocean has not been well established, although (90)Sr concentrations recorded in surface seawater offshore of the damaged Fukushima Dai-ichi nuclear power plant were in some areas comparable to or even higher than (as those in December 2011 with 400 kBq m(-3)(90)Sr) the (137)Cs levels. The total amount of (90)Sr released to the marine environment in the form of highly radioactive wastewater could reach about 1 PBq. Long-term series (1960-2010) of (90)Sr concentration measurements in subtropical surface waters of the western North Pacific indicated that its concentration has been decreasing gradually with a half-life of 14 y. The pre-Fukushima (90)Sr levels in surface waters, including coastal waters near Fukushima, were estimated to be 1 Bq m(-3). To better assess the impact of about 4-5 orders of magnitude increased radiostrontium levels on the marine environment, more detail measurements in seawater and biota of the western North Pacific are required.

  20. An interdecadal change in the relationship between January-March Arctic Oscillation and North Pacific Precipitation

    NASA Astrophysics Data System (ADS)

    Hu, Miao

    2014-05-01

    An analysis of variability in the relationships between the winter (January-March) Arctic Oscillation and precipitation over the Northern Pacific during the period of 1979 to 2011 is presented based on the monthly precipitation data (CMAP) and NCEP/NCAR Reanalysis, after subtracting ENSO signals from all datasets. The sliding correlation analysis demonstrates there is a prominent weakening in the AO-precipitation relation around the early 1990s. In the total 33 years a high (low) AO phase more likely accompanies with a stronger (weaker) precipitation in the subtropical Pacific, and the mainly significant correlation area ranges from 10°-30°N,150°E-190°W. During the year 1979 to 1989, the positive correlations over the tropical Pacific are significant and widely-ranged; however, the correlations weaken over the whole region and even negative over the central Pacific after the early 1990s. In addition, the Model BCCR-BCM2 is capable of simulating the correct overall AO-precipitation relation over North Pacific.

  1. Circum-North Pacific tectonostratigraphic terrane map

    USGS Publications Warehouse

    Nokleberg, Warren J.; Parfenov, Leonid M.; Monger, James W.H.; Baranov, Boris B.; Byalobzhesky, Stanislav G.; Bundtzen, Thomas K.; Feeney, Tracey D.; Fujita, Kazuya; Gordey, Steven P.; Grantz, Arthur; Khanchuk, Alexander I.; Natal'in, Boris A.; Natapov, Lev M.; Norton, Ian O.; Patton, William W.; Plafker, George; Scholl, David W.; Sokolov, Sergei D.; Sosunov, Gleb M.; Stone, David B.; Tabor, Rowland W.; Tsukanov, Nickolai V.; Vallier, Tracy L.; Wakita, Koji

    1994-01-01

    after accretion of most terranes in the region; (2) Cenozoic and Mesozoic basinal deposits that occur within a terrane or on the craton; (3) plutonic rocks. The postaccretion igneous units are identified by age-lithologic abbreviations and by name. These overlap assemblages and basinal deposits formed mainly during sedimentation and magmatism that occurred after accretion of terranes to each other or to a continental margin. Overlap assemblages provide minimum ages on the timing of accretion of terranes. Some Cenozoic and Mesozoic overlap assemblages and basinal deposits, as well as fragments of terranes, are extensively offset by movement along postaccretion faults. In addition, in onshore areas, the map depicts major preaccretion plutonic rocks that are limited to individual terranes. and in offshore areas. the map depicts major oceanic plates,-ocean floor magnetic lineations. oceanic spreading ridges, and seamounts. The map consists of five sheets. Sheets I and 2 depict, at a scale of I :5.000.000. the tectonostratigraphic terranes. preaccretion plutonic rocks, and postaccretion Cenozoic and Mesozoic overlap sedimentary, volcanic. and plutonic assemblages, and basinal deposits for the Circum- orth Pacific including the Russian Far East, northern Hokkaido Island of Japan, Alaska. the Canadian Cordillera, part of the U.S.A. Pacific Northwest. and adjacent offshore areas. Sheet 3 provides the list of map units for Sheets I and 2. Sheet 4 is a index map showing generalized onshore terranes and overlap assemblages for onshore parts of the Circum-North Pacific at a scale of I: I 0,000,000. Sheet 4 is a guide to the more complicated onshore features depicted on Sheets I and 2. Sheet 5 is an index map showing the major geographic regions for the Circum-North Pacific. Significant differences exist between the representation of onshore and offshore geology on Sheets I and 2. These are: (I) compared to the onshore part of the map, the offshore part is depicted in a more

  2. Light-driven synchrony of Prochlorococcus growth and mortality in the subtropical Pacific gyre.

    PubMed

    Ribalet, Francois; Swalwell, Jarred; Clayton, Sophie; Jiménez, Valeria; Sudek, Sebastian; Lin, Yajuan; Johnson, Zackary I; Worden, Alexandra Z; Armbrust, E Virginia

    2015-06-30

    Theoretical studies predict that competition for limited resources reduces biodiversity to the point of ecological instability, whereas strong predator/prey interactions enhance the number of coexisting species and limit fluctuations in abundances. In open ocean ecosystems, competition for low availability of essential nutrients results in relatively few abundant microbial species. The remarkable stability in overall cell abundance of the dominant photosynthetic cyanobacterium Prochlorococcus is assumed to reflect a simple food web structure strongly controlled by grazers and/or viruses. This hypothesized link between stability and ecological interactions, however, has been difficult to test with open ocean microbes because sampling methods commonly have poor temporal and spatial resolution. Here we use continuous techniques on two different winter-time cruises to show that Prochlorococcus cell production and mortality rates are tightly synchronized to the day/night cycle across the subtropical Pacific Ocean. In warmer waters, we observed harmonic oscillations in cell production and mortality rates, with a peak in mortality rate consistently occurring ∼6 h after the peak in cell production. Essentially no cell mortality was observed during daylight. Our results are best explained as a synchronized two-component trophic interaction with the per-capita rates of Prochlorococcus consumption driven either directly by the day/night cycle or indirectly by Prochlorococcus cell production. Light-driven synchrony of food web dynamics in which most of the newly produced Prochlorococcus cells are consumed each night likely enforces ecosystem stability across vast expanses of the open ocean. PMID:26080407

  3. Light-driven synchrony of Prochlorococcus growth and mortality in the subtropical Pacific gyre.

    PubMed

    Ribalet, Francois; Swalwell, Jarred; Clayton, Sophie; Jiménez, Valeria; Sudek, Sebastian; Lin, Yajuan; Johnson, Zackary I; Worden, Alexandra Z; Armbrust, E Virginia

    2015-06-30

    Theoretical studies predict that competition for limited resources reduces biodiversity to the point of ecological instability, whereas strong predator/prey interactions enhance the number of coexisting species and limit fluctuations in abundances. In open ocean ecosystems, competition for low availability of essential nutrients results in relatively few abundant microbial species. The remarkable stability in overall cell abundance of the dominant photosynthetic cyanobacterium Prochlorococcus is assumed to reflect a simple food web structure strongly controlled by grazers and/or viruses. This hypothesized link between stability and ecological interactions, however, has been difficult to test with open ocean microbes because sampling methods commonly have poor temporal and spatial resolution. Here we use continuous techniques on two different winter-time cruises to show that Prochlorococcus cell production and mortality rates are tightly synchronized to the day/night cycle across the subtropical Pacific Ocean. In warmer waters, we observed harmonic oscillations in cell production and mortality rates, with a peak in mortality rate consistently occurring ∼6 h after the peak in cell production. Essentially no cell mortality was observed during daylight. Our results are best explained as a synchronized two-component trophic interaction with the per-capita rates of Prochlorococcus consumption driven either directly by the day/night cycle or indirectly by Prochlorococcus cell production. Light-driven synchrony of food web dynamics in which most of the newly produced Prochlorococcus cells are consumed each night likely enforces ecosystem stability across vast expanses of the open ocean.

  4. Surface heat storage in the subtropical North Atlantic during the LGM

    NASA Astrophysics Data System (ADS)

    Repschlaeger, Janne; Weinelt, Mara; Garbe-Schönberg, Dieter; Andersen, Nils; Schneider, Ralph

    2016-04-01

    The transport of warm saline waters from the subtropical into the subpolar North Atlantic plays a major role in the stabilization of AMOC. During the Late Pleistocene this system experienced millennial scale variability with weak AMOC phases that are associated with heat and salt storage within the subtropics. The subsequent onset of AMOC is supposed to be fueled by the release and transport of the warm saline water into the northern hemisphere deepwater convection sites. Despite this conceptual model, contradicting reconstructions for such warm water storage exist for the Deglaciation to early Holocene and full glacial periods, either asserting a southward movement of the Subtropical gyre (STG) and subsurface heat storage or northward extension of the STG with warming of the surface waters. Here we investigate the heat and salt storage patterns and extension of the warm subtropical gyre (STG) during MIS 2 well into MIS 3 (16- 30 ka BP) at centennial scale resolution using sediment core MD08-3181 (38°N; 31.13°W, 3060 m w.d.) retrieved immediately east of the Mid Atlantic Ridge south of the Azores Islands with sedimentation rates up to 100 cm/ ka. At present, this site is located at the northern rim of the Azores Current, which delineates the STG, recirculating warm waters of the North Atlantic Current. Due to its position at the boundary between temperate Northeast Atlantic waters and warm STG waters, the coring site is ideal to trace past changes in the influence of both water masses. Parallel stable-oxygen isotope and Mg/Ca temperature records of surface-water dwelling foraminifera Globigerina bulloides (habitat depth 0-200 m) and subsurface dweller Globorotalia inflata (habitat depth 100-300 m) and foraminiferal transfer functions are used to reconstruct the temperature and salinity structure of the mixed layer. Additionally, the AF position is reconstructed using the abundance of the tropical to subtropical species Globigerinoides ruber white. Preliminary

  5. Interannual-decadal variability of wintertime mixed layer depths in the North Pacific detected by an ensemble of ocean syntheses

    NASA Astrophysics Data System (ADS)

    Toyoda, Takahiro; Fujii, Yosuke; Kuragano, Tsurane; Kosugi, Naohiro; Sasano, Daisuke; Kamachi, Masafumi; Ishikawa, Yoichi; Masuda, Shuhei; Sato, Kanako; Awaji, Toshiyuki; Hernandez, Fabrice; Ferry, Nicolas; Guinehut, Stéphanie; Martin, Matthew; Andrew Peterson, K.; Good, Simon A.; Valdivieso, Maria; Haines, Keith; Storto, Andrea; Masina, Simona; Köhl, Armin; Yin, Yonghong; Shi, Li; Alves, Oscar; Smith, Gregory; Chang, You-Soon; Vernieres, Guillaume; Wang, Xiaochun; Forget, Gael; Heimbach, Patrick; Wang, Ou; Fukumori, Ichiro; Lee, Tong; Zuo, Hao; Balmaseda, Magdalena

    2015-08-01

    The interannual-decadal variability of the wintertime mixed layer depths (MLDs) over the North Pacific is investigated from an empirical orthogonal function (EOF) analysis of an ensemble of global ocean reanalyses. The first leading EOF mode represents the interannual MLD anomalies centered in the eastern part of the central mode water formation region in phase opposition with those in the eastern subtropics and the central Alaskan Gyre. This first EOF mode is highly correlated with the Pacific decadal oscillation index on both the interannual and decadal time scales. The second leading EOF mode represents the MLD variability in the subtropical mode water (STMW) formation region and has a good correlation with the wintertime West Pacific (WP) index with time lag of 3 years, suggesting the importance of the oceanic dynamical response to the change in the surface wind field associated with the meridional shifts of the Aleutian Low. The above MLD variabilities are in basic agreement with previous observational and modeling findings. Moreover the reanalysis ensemble provides uncertainty estimates. The interannual MLD anomalies in the first and second EOF modes are consistently represented by the individual reanalyses and the amplitudes of the variabilities generally exceed the ensemble spread of the reanalyses. Besides, the resulting MLD variability indices, spanning the 1948-2012 period, should be helpful for characterizing the North Pacific climate variability. In particular, a 6-year oscillation including the WP teleconnection pattern in the atmosphere and the oceanic MLD variability in the STMW formation region is first detected.

  6. The change features of the west boundary bifurcation line of the North Equatorial Current in the Pacific

    NASA Astrophysics Data System (ADS)

    Guo, Junru; Liu, Yulong; Song, Jun; Bao, Xianwen; Li, Yan; Chen, Shaoyang; Yang, Jinkun

    2015-12-01

    The equatorial Current in the North Pacific (NEC) is an upper layer westward ocean current, which flows to the west boundary of the ocean, east of the Philippines, and bifurcates into the northerly Kuroshio and the main body of the southerly Mindanao current. Thus, NEC is both the south branch of the Subtropical Circulation and the north branch of the Tropical Circulation. The junction of the two branches extends to the west boundary to connect the bifurcation points forming the bifurcation line. The position of the North Pacific Equatorial Current bifurcation line of the surface determines the exchange between and the distribution of subtropical and tropical circulations, thus affecting the local or global climate. A new identification method to track the line and the bifurcation channel was used in this study, focusing on the climatological characteristics of the western boundary of the North Equatorial Current bifurcation line. The long-term average NEC west boundary bifurcation line shifts northwards with depth. In terms of seasonal variation, the average position of the western boundary of the bifurcation line is southernmost in June and northernmost in December, while in terms of interannual variation, from spring to winter in the years when ENSO is developing, the position of the west boundary bifurcation line of NEC is relatively to the north (south) in EI Niño (La Niña) years as compared to normal years.

  7. The influence of north Pacific atmospheric circulation on streamflow in the west

    USGS Publications Warehouse

    Cayan, Daniel R.; Peterson, David H.

    1989-01-01

    Pacific). This index, beginning in 1899, is taken to be the average of the SLP anomaly south of the Aleutians and the western Gulf of Alaska. Correlations between PNA or CNP and regional anomalies reflect streamflow the alternations in strength and position of the mean North Pacific storm track entering North America as well as shifts in the trade winds over the subtropical North Pacific. Regions whose streamflow is best tuned to the PNA or CNP include coastal Alaska, the northwestern United States, and Hawaii; the latter two regions have the opposite sign anomaly as the former. The pattern of streamflow variations associated with El Niño is similar, but the El Niño signal also includes a tendency for greater than normal streamflow in the southwestern United States. These indices are significantly correlated with streamflow at one to two seasons in advance of the December–August period, which may allow modestly skillful forecasts. It is important to note that streamflow variability in some areas, such as British Columbia and California, does not respond consistently to these broad scale Pacific atmospheric circulation indices, but is related to regional atmospheric anomaly features over the eastern North Pacific. Spatially, streamflow anomalies are fairly well correlated over scales of several hundred kilometers. Inspection of the spatial anomalies of stream-flow in this study suggest an asymmetry in the spatial pattern of positive versus negative streamflow anomalies in the western United States: dry patterns have tended to be larger and more spatially coherent than wet patterns.

  8. A reassessment of the integrated impact of tropical cyclones on surface chlorophyll in the western subtropical North Atlantic

    NASA Astrophysics Data System (ADS)

    Foltz, Gregory R.; Balaguru, Karthik; Leung, L. Ruby

    2015-02-01

    The impact of tropical cyclones on surface chlorophyll concentration is assessed in the western subtropical North Atlantic Ocean during 1998-2011. Previous studies in this area focused on individual cyclones and gave mixed results regarding the importance of tropical cyclone-induced mixing for changes in surface chlorophyll. Using a more integrated and comprehensive approach that includes quantification of cyclone-induced changes in mixed layer depth, here it is shown that accumulated cyclone energy explains 22% of the interannual variability in seasonally averaged (June-November) chlorophyll concentration in the western subtropical North Atlantic, after removing the influence of the North Atlantic Oscillation (NAO). The variance explained by tropical cyclones is thus about 70% of that explained by the NAO, which has well-known impacts in this region. It is therefore likely that tropical cyclones contribute significantly to interannual variations of primary productivity in the western subtropical North Atlantic during the hurricane season.

  9. A Reassessment of the Integrated Impact of Tropical Cyclones on Surface Chlorophyll in the Western Subtropical North Atlantic

    SciTech Connect

    Foltz, Gregory R.; Balaguru, Karthik; Leung, Lai-Yung R.

    2015-02-28

    The impact of tropical cyclones on surface chlorophyll concentration is assessed in the western subtropical North Atlantic Ocean during 1998–2011. Previous studies in this area focused on individual cyclones and gave mixed results regarding the importance of tropical cyclone-induced mixing for changes in surface chlorophyll. Using a more integrated and comprehensive approach that includes quantification of cyclone-induced changes in mixed layer depth, here it is shown that accumulated cyclone energy explains 22% of the interannual variability in seasonally-averaged (June–November) chlorophyll concentration in the western subtropical North Atlantic, after removing the influence of the North Atlantic Oscillation (NAO). The variance explained by tropical cyclones is thus about 70% of that explained by the NAO, which has well-known impacts in this region. It is therefore likely that tropical cyclones contribute significantly to interannual variations of primary productivity in the western subtropical North Atlantic during the hurricane season.

  10. Wave power variability and trends across the North Pacific

    NASA Astrophysics Data System (ADS)

    Bromirski, Peter D.; Cayan, Daniel R.; Helly, John; Wittmann, Paul

    2013-12-01

    Multiyear climate variations influence North Pacific storm intensity and resultant variations in wave energy levels. The timing of these decadal fluctuations and strong El Niño's have had a strong influence on long-term trends. Here we investigate variations in the North Pacific wave power, PW, determined from WAVEWATCH III (WW3) wave model significant wave height, Hs, and peak period data forced by NRA-1 winds spanning the 1948-2008 epoch. Over the entire hindcast, upward trends in Hs and PW, especially in winter, are observed over much of the North Pacific, strongly influenced by an apparent storm intensification after the mid-1970s regime shift. Heightened PW is concentrated in particular regions of the basin, and is associated with increased wave activity during the warm phase of the Pacific Decadal Oscillation (PDO). Wave power events, PE, defined as episodes when Hs exceeded the 90th percentile threshold for at least 12 h, exhibit significant upward trends along much of the U.S. Pacific coast during winter months. Importantly, the hindcast exhibits a recent decrease in PW across much of the North Pacific, in contrast to the long-term increase of PW and Hs. This recent decrease is associated with the prevalent PDO cool phase that developed after the late 1990s. Variability and intensification of coastal PW and PE have important practical implications for shoreline and beach erosion, coastal wetlands inundation, storm-surge flooding, and coastal planning. These considerations will become increasingly important as sea level rises.

  11. Physical drivers of interannual chlorophyll variability in the eastern subtropical North Atlantic

    NASA Astrophysics Data System (ADS)

    Pastor, M. V.; Palter, J. B.; Pelegrí, J. L.; Dunne, J. P.

    2013-08-01

    Interannual chlorophyll variability and its driving mechanisms are evaluated in the eastern subtropical North Atlantic, where elevated surface chlorophyll concentrations regularly extend more than 1500 km into the central subtropical North Atlantic and modulate the areal extent of the North Atlantic's lowest chlorophyll waters. We first characterize the considerable interannual variability in the size of the high chlorophyll region using SeaWiFS satellite data. We then evaluate the relationship between satellite chlorophyll and sea surface height (SSH), which are anticorrelated in the study region, most likely as a result of the inverse relationship between SSH and nutricline depth. To put these results in a longer temporal context, we study a hindcast simulation of a global ocean model with biogeochemistry (GFDL's MOM4.1 with TOPAZ biogeochemistry), after evaluating the model's skill at simulating chlorophyll and SSH relative to observations. In the simulation, the variability seen during the satellite era appears to be imbedded in a much larger multidecadal modulation. The drivers of such variability are assessed by evaluating all the terms in the nutrient budget of the euphotic zone. Because diffusive processes are not a dominant control on nutrient supply, stratification is not a good indicator of nutrient supply. Rather, vertical advection of nutrients, strongly tied to Ekman pumping, is the leading driver of variability in the size of the high chlorophyll region and the productivity within the study area.

  12. Variability in the correlation between Asian dust storms and chlorophyll a concentration from the North to Equatorial Pacific.

    PubMed

    Tan, Sai-Chun; Yao, Xiaohong; Gao, Hui-Wang; Shi, Guang-Yu; Yue, Xu

    2013-01-01

    A long-term record of Asian dust storms showed seven high-occurrence-frequency centers in China. The intrusion of Asian dust into the downwind seas, including the China seas, the Sea of Japan, the subarctic North Pacific, the North Pacific subtropical gyre, and the western and eastern Equatorial Pacific, has been shown to add nutrients to ocean ecosystems and enhance their biological activities. To explore the relationship between the transported dust from various sources to the six seas and oceanic biological activities with different nutrient conditions, the correlation between monthly chlorophyll a concentration in each sea and monthly dust storm occurrence frequencies reaching the sea during 1997-2007 was examined in this study. No correlations were observed between dust and chlorophyll a concentration in the <50 m China seas because atmospheric deposition is commonly believed to exert less impact on coastal seas. Significant correlations existed between dust sources and many sea areas, suggesting a link between dust and chlorophyll a concentration in those seas. However, the correlation coefficients were highly variable. In general, the correlation coefficients (0.54-0.63) for the Sea of Japan were highest, except for that between the subarctic Pacific and the Taklimakan Desert, where it was as high as 0.7. For the >50 m China seas and the North Pacific subtropical gyre, the correlation coefficients were in the range 0.32-0.57. The correlation coefficients for the western and eastern Equatorial Pacific were relatively low (<0.36). These correlation coefficients were further interpreted in terms of the geographical distributions of dust sources, the transport pathways, the dust deposition, the nutrient conditions of oceans, and the probability of dust storms reaching the seas.

  13. Variability in the correlation between Asian dust storms and chlorophyll a concentration from the North to Equatorial Pacific.

    PubMed

    Tan, Sai-Chun; Yao, Xiaohong; Gao, Hui-Wang; Shi, Guang-Yu; Yue, Xu

    2013-01-01

    A long-term record of Asian dust storms showed seven high-occurrence-frequency centers in China. The intrusion of Asian dust into the downwind seas, including the China seas, the Sea of Japan, the subarctic North Pacific, the North Pacific subtropical gyre, and the western and eastern Equatorial Pacific, has been shown to add nutrients to ocean ecosystems and enhance their biological activities. To explore the relationship between the transported dust from various sources to the six seas and oceanic biological activities with different nutrient conditions, the correlation between monthly chlorophyll a concentration in each sea and monthly dust storm occurrence frequencies reaching the sea during 1997-2007 was examined in this study. No correlations were observed between dust and chlorophyll a concentration in the <50 m China seas because atmospheric deposition is commonly believed to exert less impact on coastal seas. Significant correlations existed between dust sources and many sea areas, suggesting a link between dust and chlorophyll a concentration in those seas. However, the correlation coefficients were highly variable. In general, the correlation coefficients (0.54-0.63) for the Sea of Japan were highest, except for that between the subarctic Pacific and the Taklimakan Desert, where it was as high as 0.7. For the >50 m China seas and the North Pacific subtropical gyre, the correlation coefficients were in the range 0.32-0.57. The correlation coefficients for the western and eastern Equatorial Pacific were relatively low (<0.36). These correlation coefficients were further interpreted in terms of the geographical distributions of dust sources, the transport pathways, the dust deposition, the nutrient conditions of oceans, and the probability of dust storms reaching the seas. PMID:23460892

  14. What Maintains the Central North Pacific Genetic Discontinuity in Pacific Herring?

    PubMed Central

    Liu, Ming; Lin, Longshan; Gao, Tianxiang; Yanagimoto, Takashi; Sakurai, Yasunori; Grant, W. Stewart

    2012-01-01

    Pacific herring show an abrupt genetic discontinuity in the central North Pacific that represents secondary contact between refuge populations previously isolated during Pleistocene glaciations. Paradoxically, high levels of gene flow produce genetic homogeneity among ocean-type populations within each group. Here, we surveyed variability in mtDNA control-region sequences (463 bp) and nine microsatellite loci in Pacific herring from sites across the North Pacific to further explore the nature of the genetic discontinuity around the Alaska Peninsula. Consistent with previous studies, little divergence (ΦST  = 0.011) was detected between ocean-type populations of Pacific herring in the North West Pacific, except for a population in the Yellow Sea (ΦST  = 0.065). A moderate reduction in genetic diversity for both mtDNA and microsatellites in the Yellow Sea likely reflects founder effects during the last colonization of this sea. Reciprocal monophyly between divergent mtDNA lineages (ΦST  = 0.391) across the Alaska Peninsula defines the discontinuity across the North Pacific. However, microsatellites did not show a strong break, as eastern Bering Sea (EBS) herring were more closely related to NE Pacific than to NW Pacific herring. This discordance between mtDNA and microsatellites may be due to microsatellite allelic convergence or to sex-biased dispersal across the secondary contact zone. The sharp discontinuity between Pacific herring populations may be maintained by high-density blocking, competitive exclusion or hybrid inferiority. PMID:23300525

  15. Holocene subsurface transport between subpolar and subtropical gyre in the North Atlantic

    NASA Astrophysics Data System (ADS)

    Repschläger, J.; Garbe-Schoenberg, C. D.; Weinelt, M.; Schneider, R. R.

    2014-12-01

    The transport of warm waters from the subtropics into the subpolar North Atlantic (NA) strongly affects the climate variability of Europe and governs the strength of NA deepwater convection and the resulting AMOC strength. Modern oceanographic studies and climate models propose that this transport is mainly driven by the interaction between the subtropical (STG) and the subpolar (STG) gyre via subsurface pathways. Paleoceanographic studies postulate that subsurface transport of warm saline water from the STG may counterbalance freshening of the SPG and stabilize the Holocene AMOC mode. We tested this hypothesis, with new stable isotope and Mg/Ca analyses from surface and subsurface dwelling foraminifera obtained from a core site situated at the northern boundary of the STG. Our new dataset indicates stable sea surface conditions and stronger variability in the subsurface temperature and salinities. During early Holocene similar subsurface temperatures and salinities in STG and SPG indicate that both regions were directly influenced by the same water mass that probably originated from NH meltwater discharges (e.g. Thornalley et al., 2009). This period is followed by a strong Mid-Holocene divergence between subpolar and STG salinity and temperature records, while the latter two properties in the STG converge towards the records from the subtropical source region (Bahr et al., 2013). We infer that this convergence was driven by a change in the source of subsurface waters due to the expansion of subtropical water masses in the Mid-Holocene. The Mid- to late Holocene (after 6 ka BP) is characterized again by in phase variations of subsurface subpolar and STG records although both temperatures and salinities differ in absolute values. This resemblance indicates a strong connection via subsurface transport between the STG and the subpolar region that probably stabilized the late Holocene NA gyre circulation.

  16. Late Tectonic history of Beaufort Sea - North Pacific area

    SciTech Connect

    McWhae, J.R.H.

    1985-02-01

    The Kaltag fault (and its northern associated splay, the Rapid fault array) is the sheared suture between the Eurasian-Alaskan plate and the North American plate in the area between the Mackenzie Delta and the Alaskan Border. This condition has been maintained throughout considerable additional phases of faulting and folding from mid-Cretaceous to the present. Previously, the Alaskan plate had been the northwestern nose of the North America plate. The interplate suture was deflected to the north as the Canadian Shield was approached. The Kaltag fault continued northeastward 2000 km seaward of the Sverdrup rim, northwest of the Canadian Arctic Island, and north of Greenland. The driving force was directed from the southwest by the Eurasian plate after its collision in Early Cretaceous (Hauterivian) with the North American plate and the docking of north-moving exotic terranes from the Pacific. During the early Tertiary, perhaps in concert with the accretion of the Okhotsk block to the Asian plate north of Japan, the northern Pacific subduction zone jumped southward to the Aleutian Arc where it has persisted until today. A distance of 800 km separates the stable shelf of the Canadian craton, at the Alberta Foothills thrust belt, from the subduction zone off Vancouver Island. The foreland thrust belt and the accretion of exotic terranes in Mesozoic and Tertiary times extended the continental crust of the North American plate westward to the present active transform margin with the Pacific plate along the Queen Charlotte fault zone.

  17. Legacy and contemporary persistent organic pollutants in North Pacific albatross.

    PubMed

    Harwani, Suhash; Henry, Robert W; Rhee, Alexandra; Kappes, Michelle A; Croll, Donald A; Petreas, Myrto; Park, June-Soo

    2011-11-01

    Here we report the first measurements of polybrominated diphenyl ethers (PBDE 47, 99, and 153) alongside 11 organochlorine pesticides (OCPs) and 28 polychlorinated biphenyls (PCBs) in the plasma of albatross from breeding colonies distributed across a large spatial east-west gradient in the North Pacific Ocean. North Pacific albatross are wide-ranging, top-level consumers that forage in pelagic regions of the North Pacific Ocean, making them an ideal sentinel species for detection and distribution of marine contaminants. Our work on contaminant burdens in albatross tissue provides information on transport of persistent organic pollutants (POPs) to the remote North Pacific and serves as a proxy for regional environmental quality. We sampled black-footed (Phoebastria nigripes; n = 20) and Laysan albatross (P. immutabilis; n = 19) nesting on Tern Island, Hawaii, USA, and Laysan albatross (n = 16) nesting on Guadalupe Island, Mexico. Our results indicate that North Pacific albatross are highly exposed to both PCBs and OCPs, with levels ranging from 8.8 to 86.9 ng/ml wet weight and 7.4 to 162.3 ng/ml wet weight, respectively. A strong significant gradient exists between Laysan albatross breeding in the Eastern Pacific, having approximately 1.5-fold and 2.5-fold higher levels for PCBs and OCPs, respectively, compared to those from the Central Pacific. Interspecies levels of contaminants within the same breeding site also showed high variation, with Tern black-footed albatross having approximately threefold higher levels of both PCBs and OCPs than Tern Laysan albatross. Surprisingly, while PBDEs are known to travel long distances and bioaccumulate in wildlife of high trophic status, we detected these three PBDE congeners only at trace levels ranging from not detectable (ND) to 0.74 ng/ml wet weight in these albatross. PMID:21898564

  18. Tropical Pacific impacts on cooling North American winters

    NASA Astrophysics Data System (ADS)

    Sigmond, Michael; Fyfe, John C.

    2016-10-01

    The North American continent generally experienced a cooling trend in winter over the early 2000s. This cooling trend represented a significant deviation from expected anthropogenic warming and so requires explanation. Previous studies indicate that climate variations in the tropical Pacific contributed to many mid-latitude climate variations over the early twenty-first century. Here we show using large ensembles of fully coupled, partially coupled and uncoupled model simulations that in northwest North America the winter cooling was primarily a remote response to climate fluctuations in the tropical Pacific. By contrast, in central North America the winter cooling appears to have resulted from a relatively rare fluctuation in mid-latitude circulation that was unrelated to the tropical Pacific. Our results highlight how decadal climate signals--both remote and local in origin--can together offset anthropogenic warming to produce continental-scale cooling.

  19. Late Neogene changes in diatom sedimentation in the North Pacific

    USGS Publications Warehouse

    Barron, J.A.

    1998-01-01

    During the late Neogene, North Pacific diatom sedimentation underwent major changes in response to high-latitude cooling and changes in surface and deep water circulation. At 9 Ma diatom mass accumulation rates (MARs) increased in the NW Pacific and off northeast Japan, possibly due to shoaling of the Isthmus of Panama, which lead to an enrichment of nutrients in North Pacific deep waters. During the latest Miocene, diatom MARs increased progressively off southern California (6.5 Ma), at high latitudes of the North Pacific (6.2 Ma), and off northeastern Japan (5.5 Ma), presumably in response to high latitude cooling. At about 4.5 Ma diatom sedimentation abruptly increased in the NW Pacific but declined off Japan and California, coincident with the onset of a prolonged period of high-latitude warmth. Enhanced upwelling of nutrient-rich deep waters in the NW Pacific probably stimulated diatom production there. A major step in high latitude cooling at 2.7 Ma caused a reversal of these mid Pliocene diatom sedimentation patterns. Upwelling of deep, nutrient-rich waters waned at higher latitudes, leading to a decline in diatom productivity; while wind-driven, coastal upwelling increased off southern California and stimulated diatom growth.

  20. Different responses of Sea Surface Temperature in the North Pacific to greenhouse gas and aerosol forcing

    NASA Astrophysics Data System (ADS)

    Wang, Liyi; Liu, Qinyu

    2015-12-01

    The responses of Sea Surface Temperature (SST) to greenhouse gas (GHG) and anthropogenic aerosol in the North Pacific are compared based on the historical single and all-forcing simulations with Geophysical Fluid Dynamics Laboratory Climate Model version 3 (GFDL CM3). During 1860-2005, the effect of GHG forcing on the North Pacific SST is opposite to that of the aerosol forcing. Specifically, the aerosol cooling effect exceeds the GHG warming effect in the Kuroshio Extension (KE) region during 1950-2004 in the CM3 single forcing. The mid-latitude response of ocean circulation to the GHG (aerosol) forcing is to enhance (weaken) the Subtropical Gyre. Then the SST warming (cooling) lies on the zonal band of 40°N because of the increased (reduced) KE warm advection effect in the GHG (aerosol) forcing simulations, and the cooling effect to SST will surpass the warming effect in the KE region in the historical all-forcing simulations. Besides, the positive feedback between cold SST and cloud can also strengthen the aerosol cooling effect in the KE region during boreal summer, when the mixed layer depth is shallow. In the GHG (aerosol) forcing simulations, corresponding to warming (cooling) SST in the KE region, the weakened (enhanced) Aleutian Low appears in the Northeast Pacific. Consequently, the SST responses to all-forcing in the historical simulations are similar to the responses to aerosol forcing in sign and spatial pattern, hence the aerosol effect is quite important to the SST cooling in the mid-latitude North Pacific during the past 55 years.

  1. The cycle of atmospheric cadmium in the remote North Pacific

    SciTech Connect

    Patterson, T.L.

    1989-01-01

    Bulk aerosol, cascade impactor, rain and seawater samples were specially collected for cadmium, lead, aluminum and sodium measurements during the spring season. The samples were collected during the SEAREX (Sea-Air Exchange) Program's North Pacific Westerlies Cruises and at the SEAREX Asian Dust Sampling network station on the island of Oahu, Hawaii. Aerosol samples were also collected at a third station located on the Pacific Coast of the Olympic Peninsula in the state of Washington. The data indicate that the most likely primary source of cadmium over the central North Pacific is pollutant aerosol produced in Asia that has been rapidly transported through the upper troposphere to the remote North Pacific boundary layer. The deposition rate of atmospheric cadmium was estimated using wet and dry deposition models coupled with cadmium concentration data. Based on these estimates, the net deposition of pollutant cadmium comprises between 90 and 100% of the gross flux, and wet deposition represents between 80 and 90% of the flux. The flux of cadmium from the atmosphere to the ocean during the spring is estimated to be an insignificant source of cadmium in the surface waters of the central North Pacific Ocean compared to the horizontal and vertical advection and diffusion of dissolved cadmium. The dissolvability of cadmium from aerosols into seawater was also measured as a part of this research. Based on the results of a limited number of replicate experiments, greater than approximately 90% of the cadmium in the bulk aerosol dissolves in seawater within six hours.

  2. Conservation of native Pacific trout diversity in western North America

    USGS Publications Warehouse

    Penaluna, Brooke E.; Abadía-Cardoso, Alicia; Dunham, Jason; García de León, Francisco J; Gresswell, Robert E.; Luna, Arturo Ruiz; Taylor, Eric B.; Shepard, Bradley B.; Al-Chokhachy, Robert K.; Muhlfeld, Clint C.; Bestgen, Kevin R.; Rogers, Kevin H.; Escalante, Marco A; Keeley, Ernest R; Temple, Gabriel; Williams, Jack E.; Matthews, Kathleen; Pierce, Ron; Mayden, Richard L.; Kovach, Ryan; Garza, John Carlos; Fausch, Kurt D.

    2016-01-01

    Pacific trout Oncorhynchus spp. in western North America are strongly valued in ecological, socioeconomic, and cultural views, and have been the subject of substantial research and conservation efforts. Despite this, the understanding of their evolutionary histories, overall diversity, and challenges to their conservation is incomplete. We review the state of knowledge on these important issues, focusing on Pacific trout in the genus Oncorhynchus. Although most research on salmonid fishes emphasizes Pacific salmon, we focus on Pacific trout because they share a common evolutionary history, and many taxa in western North America have not been formally described, particularly in the southern extent of their ranges. Research in recent decades has led to the revision of many hypotheses concerning the origin and diversification of Pacific trout throughout their range. Although there has been significant success at addressing past threats to Pacific trout, contemporary and future threats represented by nonnative species, land and water use activities, and climate change pose challenges and uncertainties. Ultimately, conservation of Pacific trout depends on how well these issues are understood and addressed, and on solutions that allow these species to coexist with a growing scope of human influences.

  3. Insight into the Pacific Sea Surface Temperature- North American Hydroclimate Connection from an Eastern Tropical North Pacific Coral Record

    NASA Astrophysics Data System (ADS)

    Svendsen, J. I.; Briner, J. P.; Mangerud, J.; Hughes, A. L. C.; Young, N. E.; Vasskog, K.

    2014-12-01

    The last few years of record-breaking climate anomalies across North America--a resilient atmospheric ridge and extreme drought over the West Coast, and severe winters across the Midwest and East Coast regions--have been linked to anomalous Pacific sea surface temperatures (Seager et al. 2014, Wang et al. 2014, Hartmann 2015). The synoptic associations prompt important questions on the relation between these unusual phenomena and extreme expressions of known Pacific decadal modes, such as the North Pacific Gyre Oscillation (NPGO). These questions motivate our pursuit to document multiple realizations of decadal variability in the Pacific-North American region through periods of varied radiative forcing. Here we introduce a 178 year, seasonally resolved Porites coral record from Clarion Island (18N, 115W), the westernmost island of the Revillagigedo Archipelago, a region both highly influenced by NPGO SST and SSS variability and critical for NPGO tropical-extratropical communication via the Seasonal Footprinting Mechanism (Vimont et al. 2003). When coupled with tree ring records from the western United States (Griffin and Anchukaitis 2014, MacDonald and Case 2005) and coral records from the central tropical Pacific (Cobb et al. 2001), the δ18O signal from the Clarion coral offers an extended framework of coherent continental hydroclimate and oceanic variability across the Pacific basin beyond the instrumental record. Over the last 200 years, we find clear commonality in the timing, magnitude and spatial expression of variability (illustrated through the NADA Atlas, Cook et al. 2004) amongst the proxy records. The strong relationship between Northeastern Pacific Clarion and the Central Pacific Palmyra record with the North American hydroclimate records can be viewed within the mechanistic framework of the NPGO; this framework is then explored over the last millennium across intervals of varied radiative forcing.

  4. Insight into the Pacific Sea Surface Temperature- North American Hydroclimate Connection from an Eastern Tropical North Pacific Coral Record

    NASA Astrophysics Data System (ADS)

    Sanchez, S. C.; Charles, C. D.; Carriquiry, J. D.

    2015-12-01

    The last few years of record-breaking climate anomalies across North America--a resilient atmospheric ridge and extreme drought over the West Coast, and severe winters across the Midwest and East Coast regions--have been linked to anomalous Pacific sea surface temperatures (Seager et al. 2014, Wang et al. 2014, Hartmann 2015). The synoptic associations prompt important questions on the relation between these unusual phenomena and extreme expressions of known Pacific decadal modes, such as the North Pacific Gyre Oscillation (NPGO). These questions motivate our pursuit to document multiple realizations of decadal variability in the Pacific-North American region through periods of varied radiative forcing. Here we introduce a 178 year, seasonally resolved Porites coral record from Clarion Island (18N, 115W), the westernmost island of the Revillagigedo Archipelago, a region both highly influenced by NPGO SST and SSS variability and critical for NPGO tropical-extratropical communication via the Seasonal Footprinting Mechanism (Vimont et al. 2003). When coupled with tree ring records from the western United States (Griffin and Anchukaitis 2014, MacDonald and Case 2005) and coral records from the central tropical Pacific (Cobb et al. 2001), the δ18O signal from the Clarion coral offers an extended framework of coherent continental hydroclimate and oceanic variability across the Pacific basin beyond the instrumental record. Over the last 200 years, we find clear commonality in the timing, magnitude and spatial expression of variability (illustrated through the NADA Atlas, Cook et al. 2004) amongst the proxy records. The strong relationship between Northeastern Pacific Clarion and the Central Pacific Palmyra record with the North American hydroclimate records can be viewed within the mechanistic framework of the NPGO; this framework is then explored over the last millennium across intervals of varied radiative forcing.

  5. Albatross species demonstrate regional differences in North Pacific marine contamination

    USGS Publications Warehouse

    Finkelstein, M.; Keitt, B.S.; Croll, D.A.; Tershy, B.; Jarman, Walter M.; Rodriguez-Pastor, S.; Anderson, D.J.; Sievert, P.R.; Smith, D.R.

    2006-01-01

    Recent concern about negative effects on human health from elevated organochlorine and mercury concentrations in marine foods has highlighted the need to understand temporal and spatial patterns of marine pollution. Seabirds, long-lived pelagic predators with wide foraging ranges, can be used as indicators of regional contaminant patterns across large temporal and spatial scales. Here we evaluate contaminant levels, carbon and nitrogen stable isotope ratios, and satellite telemetry data from two sympatrically breeding North Pacific albatross species to demonstrate that (1) organochlorine and mercury contaminant levels are significantly higher in the California Current compared to levels in the high-latitude North Pacific and (2) levels of organochlorine contaminants in the North Paci.c are increasing over time. Black-footed Albatrosses (Phoebastria nigripes) had 370-460% higher organochlorine (polychlorinated biphenyls [PCBs], dichlorodiphenyltrichloroethanes [DDTs]) and mercury body burdens than a closely related species, the Laysan Albatross (P. immutabilis), primarily due to regional segregation of their North Pacific foraging areas. PCBs (the sum of the individual PCB congeners analyzed) and DDE concentrations in both albatross species were 130-360% higher than concentrations measured a decade ago. Our results demonstrate dramatically high and increasing contaminant concentrations in the eastern North Pacific Ocean, a finding relevant to other marine predators, including humans. ?? 2006 by the Ecological Society of America.

  6. Modeling the drift of massive icebergs to the subtropical North Atlantic

    NASA Astrophysics Data System (ADS)

    Condron, A.; Hill, J. C.

    2013-12-01

    New evidence from high-resolution seafloor bathymetry data indicates that massive (>300m thick) icebergs from the Laurentide Ice Sheet (LIS) drifted south to the tip of Florida during the last deglaciation. This finding is particularly exciting as it contradicts evidence from marine sediments that icebergs were mainly confined to the subpolar North Atlantic (50 - 70N) at this time. Indeed, the freshwater released from icebergs melting in the subpolar gyre is repeatedly cited as a main trigger for a slow-down of the Atlantic MOC in the past, and the possible cause of any climate cooling related to the melting of the Greenland Ice Sheet in the future. Using a sophisticated iceberg model (MITberg), coupled to a high (18-km; 1/6 deg.) resolution ocean model (MITgcm), we investigate the ocean circulation dynamics required to allow icebergs to drift to the southern tip of Florida. We find that icebergs only reach this location if they turn right at the Grand Banks of Newfoundland, and stay inshore of the Gulf Stream all the way to Florida. Modern-day circulation dynamics do not readily allow this to happen as cold, southward flowing, Labrador Current Water (important for iceberg survival) has little penetration south of Cape Hatteras. However, when a liquid meltwater flood is released from Hudson Bay at the same time, icebergs are rapidly transported (inshore of the Gulf Stream) in a narrow, buoyant, coastal current all the way to southern Florida. The meltwater and icebergs result in a significant freshening of the subtropical North Atlantic and weaken the strength of the Gulf Stream, suggesting such an event would have a large cooling effect on climate. We are only able to simulate the flow of meltwater and icebergs to the subtropics by modeling ocean circulation at a resolution that is 5 - 10 times higher than the majority of existing paleoclimate models; at lower resolutions the narrow, coastal boundary currents important for iceberg transport to the subtropics are

  7. Composite and case study analyses of the large-scale environments associated with West Pacific Polar and subtropical vertical jet superposition events

    NASA Astrophysics Data System (ADS)

    Handlos, Zachary J.

    Though considerable research attention has been devoted to examination of the Northern Hemispheric polar and subtropical jet streams, relatively little has been directed toward understanding the circumstances that conspire to produce the relatively rare vertical superposition of these usually separate features. This dissertation investigates the structure and evolution of large-scale environments associated with jet superposition events in the northwest Pacific. An objective identification scheme, using NCEP/NCAR Reanalysis 1 data, is employed to identify all jet superpositions in the west Pacific (30-40°N, 135-175°E) for boreal winters (DJF) between 1979/80 - 2009/10. The analysis reveals that environments conducive to west Pacific jet superposition share several large-scale features usually associated with East Asian Winter Monsoon (EAWM) northerly cold surges, including the presence of an enhanced Hadley Cell-like circulation within the jet entrance region. It is further demonstrated that several EAWM indices are statistically significantly correlated with jet superposition frequency in the west Pacific. The life cycle of EAWM cold surges promotes interaction between tropical convection and internal jet dynamics. Low potential vorticity (PV), high theta e tropical boundary layer air, exhausted by anomalous convection in the west Pacific lower latitudes, is advected poleward towards the equatorward side of the jet in upper tropospheric isentropic layers resulting in anomalous anticyclonic wind shear that accelerates the jet. This, along with geostrophic cold air advection in the left jet entrance region that drives the polar tropopause downward through the jet core, promotes the development of the deep, vertical PV wall characteristic of superposed jets. West Pacific jet superpositions preferentially form within an environment favoring the aforementioned characteristics regardless of EAWM seasonal strength. Post-superposition, it is shown that the west Pacific

  8. 75 FR 20566 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-20

    ... National Oceanic and Atmospheric Administration RIN 0648-XV88 North Pacific Fishery Management Council... Management Council's Gulf of Alaska (GOA) and Bering Sea/Aleutian Islands (BSAI) groundfish plan teams will meet via teleconference May 6, 2010, 12:30 p.m. Alaska Standard Time (AST) to review proposals...

  9. 77 FR 51521 - North Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-24

    ... Council's (Council) Gulf of Alaska (GOA) and Bering Sea/Aleutian Islands (BS/AI) groundfish plan teams... Science Center, 7600 Sand Point Way NE., Building 4, National Marine Mammal Lab Room 2039 (GOA Plan Team) and Traynor Room 2076 (BS/AI Plan Team), Seattle, WA. Council address: North Pacific...

  10. 77 FR 35359 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-13

    ... (Council) Golden King Crab Price Formula Committee is holding a meeting at the North Pacific Fishery... meeting concerning the arbitration system that is part of the Bering Sea and Aleutian Islands crab... golden king crab under the arbitration system. Additional information is posted on the Council Web...

  11. 77 FR 59901 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-01

    ... potential management measures, using the status quo management measures of one fish less than 45 inches or... National Oceanic and Atmospheric Administration RIN 0648-XC259 North Pacific Fishery Management Council... Management Council (Council) Charter Management Implementation Committee will convene via a conference...

  12. 78 FR 70018 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-22

    ... fish with a maximum size limit; and (4) Status quo management of one fish less than 45 inches or greater than 68 inches. For Regulatory Area 3A: (1) Status quo management of a bag limit of two fish, with... National Oceanic and Atmospheric Administration RIN 0648-XC990 North Pacific Fishery Management...

  13. 77 FR 12814 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-02

    ... (Council) and Alaska Board of Fisheries (AK BOF) Joint Protocol Committee. SUMMARY: The North Pacific Fishery Management Council Joint Protocol Committee of the AK BOF and Council will meet in March in.../ . Although non-emergency issues not contained in this agenda may come before this group for discussion,...

  14. 77 FR 56611 - North Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-13

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE... the Anchorage Hilton Hotel, 500 W. 3rd Avenue, Anchorage, AK. Council address: North Pacific Fishery...; Final action on Halibut Catch Share Plan; Charter Halibut: Review Methodology for 2013 limits (SSC...

  15. 76 FR 13360 - North Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-11

    .../approve salmon excluder EFP; review discussion paper on AFA impacts on Bering Sea cod trawlers. 10. Staff... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE... Hotel, 500 West 3rd Avenue, Anchorage, AK. Council address: North Pacific Fishery Management...

  16. 75 FR 970 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-07

    ... Alaska Fishery Science Center, 7600 Sand Point Way NE, Bldg 4, Traynor Conference Center, Seattle, WA... National Oceanic and Atmospheric Administration RIN: 0648-XT58 North Pacific Fishery Management Council; Public Meeting AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and...

  17. 78 FR 27366 - North Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-10

    ... Hall, 101 Egan Drive, Juneau, AK. DATES: The Council will begin its plenary session at 8 a.m. on..., June 4, from 1 p.m. to 5 p.m. at the Goldbelt Hotel, 51 Egan Drive, Chilkat Room, Juneau, AK. All... Centennial Hall, 101 Egan Drive, Juneau, AK. Council address: North Pacific Fishery Management Council, 605...

  18. Eolian dust input to the Subarctic North Pacific

    NASA Astrophysics Data System (ADS)

    Serno, Sascha; Winckler, Gisela; Anderson, Robert F.; Hayes, Christopher T.; McGee, David; Machalett, Björn; Ren, Haojia; Straub, Susanne M.; Gersonde, Rainer; Haug, Gerald H.

    2014-02-01

    Eolian dust is a significant source of iron and other nutrients that are essential for the health of marine ecosystems and potentially a controlling factor of the high nutrient-low chlorophyll status of the Subarctic North Pacific. We map the spatial distribution of dust input using three different geochemical tracers of eolian dust, 4He, 232Th and rare earth elements, in combination with grain size distribution data, from a set of core-top sediments covering the entire Subarctic North Pacific. Using the suite of geochemical proxies to fingerprint different lithogenic components, we deconvolve eolian dust input from other lithogenic inputs such as volcanic ash, ice-rafted debris, riverine and hemipelagic input. While the open ocean sites far away from the volcanic arcs are dominantly composed of pure eolian dust, lithogenic components other than eolian dust play a more crucial role along the arcs. In sites dominated by dust, eolian dust input appears to be characterized by a nearly uniform grain size mode at ∼4 μm. Applying the 230Th-normalization technique, our proxies yield a consistent pattern of uniform dust fluxes of 1-2 g/m2/yr across the Subarctic North Pacific. Elevated eolian dust fluxes of 2-4 g/m2/yr characterize the westernmost region off Japan and the southern Kurile Islands south of 45° N and west of 165° E along the main pathway of the westerly winds. The core-top based dust flux reconstruction is consistent with recent estimates based on dissolved thorium isotope concentrations in seawater from the Subarctic North Pacific. The dust flux pattern compares well with state-of-the-art dust model predictions in the western and central Subarctic North Pacific, but we find that dust fluxes are higher than modeled fluxes by 0.5-1 g/m2/yr in the northwest, northeast and eastern Subarctic North Pacific. Our results provide an important benchmark for biogeochemical models and a robust approach for downcore studies testing dust-induced iron fertilization of

  19. Estimating diffusivity from the mixed layer heat and salt balances in the North Pacific

    NASA Astrophysics Data System (ADS)

    Cronin, M. F.; Pelland, N.; Emerson, S. R.; Crawford, W. R.

    2015-12-01

    Data from two National Oceanographic and Atmospheric Administration (NOAA) surface moorings in the North Pacific, in combination with data from satellite, Argo floats and glider (when available), are used to evaluate the residual diffusive flux of heat across the base of the mixed layer from the surface mixed layer heat budget. The diffusion coefficient (i.e., diffusivity) is then computed by dividing the diffusive flux by the temperature gradient in the 20-m transition layer just below the base of the mixed layer. At Station Papa in the NE Pacific subpolar gyre, this diffusivity is 1×10-4 m2/s during summer, increasing to ~3×10-4 m2/s during fall. During late winter and early spring, diffusivity has large errors. At other times, diffusivity computed from the mixed layer salt budget at Papa correlate with those from the heat budget, giving confidence that the results are robust for all seasons except late winter-early spring and can be used for other tracers. In comparison, at the Kuroshio Extension Observatory (KEO) in the NW Pacific subtropical recirculation gyre, somewhat larger diffusivity are found based upon the mixed layer heat budget: ~ 3×10-4 m2/s during the warm season and more than an order of magnitude larger during the winter, although again, wintertime errors are large. These larger values at KEO appear to be due to the increased turbulence associated with the summertime typhoons, and weaker wintertime stratification.

  20. Estimating diffusivity from the mixed layer heat and salt balances in the North Pacific

    NASA Astrophysics Data System (ADS)

    Cronin, Meghan F.; Pelland, Noel A.; Emerson, Steven R.; Crawford, William R.

    2015-11-01

    Data from two National Oceanographic and Atmospheric Administration (NOAA) surface moorings in the North Pacific, in combination with data from satellite, Argo floats and glider (when available), are used to evaluate the residual diffusive flux of heat across the base of the mixed layer from the surface mixed layer heat budget. The diffusion coefficient (i.e., diffusivity) is then computed by dividing the diffusive flux by the temperature gradient in the 20 m transition layer just below the base of the mixed layer. At Station Papa in the NE Pacific subpolar gyre, this diffusivity is 1 × 10-4 m2/s during summer, increasing to ˜3 × 10-4 m2/s during fall. During late winter and early spring, diffusivity has large errors. At other times, diffusivity computed from the mixed layer salt budget at Papa correlate with those from the heat budget, giving confidence that the results are robust for all seasons except late winter-early spring and can be used for other tracers. In comparison, at the Kuroshio Extension Observatory (KEO) in the NW Pacific subtropical recirculation gyre, somewhat larger diffusivities are found based upon the mixed layer heat budget: ˜ 3 × 10-4 m2/s during the warm season and more than an order of magnitude larger during the winter, although again, wintertime errors are large. These larger values at KEO appear to be due to the increased turbulence associated with the summertime typhoons, and weaker wintertime stratification.

  1. Precessional forced extratropical North Pacific mode and associated atmospheric dynamics

    NASA Astrophysics Data System (ADS)

    Wang, Yue; Zhao, Ping; Jian, Zhimin; Xiao, Dong; Chen, Junming

    2014-06-01

    Using transient accelerated simulations of the Community Climate System Model version 3 and an Earth System Model of Intermediate Complexity as well as equilibrium experiments of the Community Earth System Model, we identified a response of the extratropical air-ocean coupled system to the precessional insolation changes at orbital timescales and named this extratropical response pattern as the North Pacific mode (NPM). Corresponding to the increased/decreased boreal winter/summer insolation at 22 ka (relative to 10-8 ka), the NPM is characterized by a western warm-eastern cold seesaw pattern of sea surface temperature (SST) over the extratropical North Pacific from November to April, a weakened winter Aleutian low and an anomalous anticyclonic circulation throughout the troposphere. This feature forms a barotropic warm-ridge response of tropospheric temperature and geopotential height to the precessional insolation. At the surface, rainfall increases over East Asia and the Northwest Pacific, which indicates a weakened East Asian winter monsoon, while drier conditions appear over the Northeast Pacific and the western coasts of North America. Associated with a negative phase of NPM is a weaker warming over the equatorial Pacific during winter. The increased winter insolation at precessional band not only induces the in-phase SST warming over the Northwest Pacific and the tropical Pacific, but also explains those extratropical atmospheric changes associated with NPM. The latter might be associated with the warm SST-induced tropospheric downstream ridge response through transient eddy activities. Besides the vital role of air-ocean interactions, the decreased summer insolation is also essential to the zonal SST seesaw of NPM at precessional band.

  2. Abstracting the Pacific Ocean's Impact on North Atlantic Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Faghmous, J.; Le, M.; Liess, S.; Mesquita, M.; Kumar, V.

    2012-12-01

    The warming anomalies of sea surface temperatures (SSTs) along the near- equatorial Pacific Ocean (ENSO) have well documented global long-range weather teleconnections from rainfall in southern India to mudslides in the western United States. In this work, we focus on ENSO's teleconnections with North Atlantic tropical cyclone (TC) activity. Traditionally, ENSO's impact on Atlantic TCs has been abstracted by monitoring the warming of static regions along the equatorial Pacific Ocean. We propose that the spatial distribution of Pacific Ocean warming might provide better predictive insights into ENSO-Atlantic TC impact than warming anomalies alone. We present a distance-based ENSO index (S-ENSO for spatial ENSO) that tracks the location of the maximum near-tropical Pacific warming anomaly instead the absolute warming of a static region. Our spatial ENSO index correlates better with seasonal TC activity than standard ENSO indices, especially with increased lead times.

  3. Nimbus-7 total ozone observations of western North Pacific tropical cyclones

    NASA Technical Reports Server (NTRS)

    Stout, John; Rodgers, Edward B.

    1992-01-01

    The Nimbus-7 Total Ozone Mapping Spectrometer (TOMS) was used to map the distribution of total ozone around western North Pacific tropical cyclones from 1979 to 1982. The strong correlation between total ozone distribution and tropopause height found in the subtropical and midlatitudes made it possible for TOMS to monitor the propagation of upper-tropospheric waves and the mutual adjustment between these waves and tropical cyclones during their interaction. Changes in these total ozone patterns reflect the 3D upper-tropospheric transport processes that are involved in tropical cyclone intensity and intensity and motion changes. The total ozone distributions indicate that: (1) the mean upper-tropospheric circulations associated with western North Pacific and Atlantic tropical cyclones are similar; (2) more intense tropical cyclones have higher tropopauses around their centers; (3) more intense tropical cyclones have higher tropopauses on the anticyclonic-shear side of their outflow jets, which indicate that the more intense tropical cyclones have stronger outflow channels than less intense systems; (4) tropical cyclones that intensify (do not intensify) are within 10 deg (15 deg) latitude of weak (strong) upper-tropospheric troughs that are moderately rich (very rich) in total ozone; and (5) tropical cyclones turn to the left (right) when they move within approximately 15 deg latitude downstream of an ozone-poor (ozone-rich) upper-tropospheric ridge (trough).

  4. 50 CFR 226.215 - Critical habitat for the North Pacific Right Whale (Eubalaena japonica).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 10 2013-10-01 2013-10-01 false Critical habitat for the North Pacific... DESIGNATED CRITICAL HABITAT § 226.215 Critical habitat for the North Pacific Right Whale (Eubalaena japonica... 57°03′ N/153°00′ W. (d) Maps of critical habitat for the North Pacific right whale follow:...

  5. 50 CFR 226.215 - Critical habitat for the North Pacific Right Whale (Eubalaena japonica).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 10 2014-10-01 2014-10-01 false Critical habitat for the North Pacific... DESIGNATED CRITICAL HABITAT § 226.215 Critical habitat for the North Pacific Right Whale (Eubalaena japonica... 57°03′ N/153°00′ W. (d) Maps of critical habitat for the North Pacific right whale follow:...

  6. Microphysical properties of low clouds over the North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Maruyama, Takumi; Hayasaka, Tadahiro

    2012-11-01

    Low clouds are widespread over the North Pacific Ocean during summer. Past ship observations, which were carried out in the western region of the North Pacific Ocean, suggested that low clouds (stratus and fog) are likely to occur when sea surface temperature (SST) is lower than surface air temperature (SAT). In this study, we investigated the SST-SAT relationship and microphysical properties of low clouds for the first step of understanding the mechanism of cloud occurrence, maintenance and disappearance by using MODIS satellite observations, JAMSTEC ship observations and MERRA reanalysis data. We divided the North Pacific into four regions according to meteorological condition and made basic statistical analysis about cloud properties in each region by using monthly mean data for July 2011. The statistical analysis indicates that in the central region of the North Pacific where SST-SAT value is negative and the difference is the largest, cloud effective particle radius (re) is larger than those in other regions. We also used ship observation data and simultaneous satellite observation data to examine the relationship between SST-SAT and cloud microphysical properties in detail. This analysis indicates that re in the positive SST-SAT area is larger than that in the negative SSTSAT area. This feature is opposite to the monthly mean results. It suggests that other factors such as humidity and aerosols as well as SST-SAT have to be taken into account, although the SST-SAT relationship can be one of the important factors determining cloud microphysical properties in the summer North Pacific region.

  7. Structure and dynamics of decadal anomalies in the wintertime midlatitude North Pacific ocean-atmosphere system

    NASA Astrophysics Data System (ADS)

    Fang, Jiabei; Yang, Xiu-Qun

    2015-12-01

    The structure and dynamics of decadal anomalies in the wintertime midlatitude North Pacific ocean-atmosphere system are examined in this study, using the NCEP/NCAR atmospheric reanalysis, HadISST SST and Simple Ocean Data Assimilation data for 1960-2010. The midlatitude decadal anomalies associated with the Pacific Decadal Oscillation are identified, being characterized by an equivalent barotropic atmospheric low (high) pressure over a cold (warm) oceanic surface. Such a unique configuration of decadal anomalies can be maintained by an unstable ocean-atmosphere interaction mechanism in the midlatitudes, which is hypothesized as follows. Associated with a warm PDO phase, an initial midlatitude surface westerly anomaly accompanied with intensified Aleutian low tends to force a negative SST anomaly by increasing upward surface heat fluxes and driving southward Ekman current anomaly. The SST cooling tends to increase the meridional SST gradient, thus enhancing the subtropical oceanic front. As an adjustment of the atmospheric boundary layer to the enhanced oceanic front, the low-level atmospheric meridional temperature gradient and thus the low-level atmospheric baroclinicity tend to be strengthened, inducing more active transient eddy activities that increase transient eddy vorticity forcing. The vorticity forcing that dominates the total atmospheric forcing tends to produce an equivalent barotropic atmospheric low pressure north of the initial westerly anomaly, intensifying the initial anomalies of the midlatitude surface westerly and Aleutian low. Therefore, it is suggested that the midlatitude ocean-atmosphere interaction can provide a positive feedback mechanism for the development of initial anomaly, in which the oceanic front and the atmospheric transient eddy are the indispensable ingredients. Such a positive ocean-atmosphere feedback mechanism is fundamentally responsible for the observed decadal anomalies in the midlatitude North Pacific ocean

  8. Structure and dynamics of decadal anomalies in the wintertime midlatitude North Pacific ocean-atmosphere system

    NASA Astrophysics Data System (ADS)

    Fang, Jiabei; Yang, Xiu-Qun

    2016-09-01

    The structure and dynamics of decadal anomalies in the wintertime midlatitude North Pacific ocean-atmosphere system are examined in this study, using the NCEP/NCAR atmospheric reanalysis, HadISST SST and Simple Ocean Data Assimilation data for 1960-2010. The midlatitude decadal anomalies associated with the Pacific Decadal Oscillation are identified, being characterized by an equivalent barotropic atmospheric low (high) pressure over a cold (warm) oceanic surface. Such a unique configuration of decadal anomalies can be maintained by an unstable ocean-atmosphere interaction mechanism in the midlatitudes, which is hypothesized as follows. Associated with a warm PDO phase, an initial midlatitude surface westerly anomaly accompanied with intensified Aleutian low tends to force a negative SST anomaly by increasing upward surface heat fluxes and driving southward Ekman current anomaly. The SST cooling tends to increase the meridional SST gradient, thus enhancing the subtropical oceanic front. As an adjustment of the atmospheric boundary layer to the enhanced oceanic front, the low-level atmospheric meridional temperature gradient and thus the low-level atmospheric baroclinicity tend to be strengthened, inducing more active transient eddy activities that increase transient eddy vorticity forcing. The vorticity forcing that dominates the total atmospheric forcing tends to produce an equivalent barotropic atmospheric low pressure north of the initial westerly anomaly, intensifying the initial anomalies of the midlatitude surface westerly and Aleutian low. Therefore, it is suggested that the midlatitude ocean-atmosphere interaction can provide a positive feedback mechanism for the development of initial anomaly, in which the oceanic front and the atmospheric transient eddy are the indispensable ingredients. Such a positive ocean-atmosphere feedback mechanism is fundamentally responsible for the observed decadal anomalies in the midlatitude North Pacific ocean

  9. Orientation behaviour of leatherback sea turtles within the North Atlantic subtropical gyre

    PubMed Central

    Dodge, Kara L.; Galuardi, Benjamin; Lutcavage, Molly E.

    2015-01-01

    Leatherback sea turtles (Dermochelys coriacea) travel thousands of kilometres between temperate feeding and tropical breeding/over-wintering grounds, with adult turtles able to pinpoint specific nesting beaches after multi-year absences. Their extensive migrations often occur in oceanic habitat where limited known sensory information is available to aid in orientation. Here, we examined the migratory orientation of adult male, adult female and subadult leatherbacks during their open-ocean movements within the North Atlantic subtropical gyre by analysing satellite-derived tracks from fifteen individuals over a 2-year period. To determine the turtles' true headings, we corrected the reconstructed tracks for current drift and found negligible differences between current-corrected and observed tracks within the gyre. Individual leatherback headings were remarkably consistent throughout the subtropical gyre, with turtles significantly oriented to the south-southeast. Adult leatherbacks of both sexes maintained similar mean headings and showed greater orientation precision overall. The consistent headings maintained by adult and subadult leatherbacks within the gyre suggest use of a common compass sense. PMID:25761714

  10. Orientation behaviour of leatherback sea turtles within the North Atlantic subtropical gyre.

    PubMed

    Dodge, Kara L; Galuardi, Benjamin; Lutcavage, Molly E

    2015-04-01

    Leatherback sea turtles (Dermochelys coriacea) travel thousands of kilometres between temperate feeding and tropical breeding/over-wintering grounds, with adult turtles able to pinpoint specific nesting beaches after multi-year absences. Their extensive migrations often occur in oceanic habitat where limited known sensory information is available to aid in orientation. Here, we examined the migratory orientation of adult male, adult female and subadult leatherbacks during their open-ocean movements within the North Atlantic subtropical gyre by analysing satellite-derived tracks from fifteen individuals over a 2-year period. To determine the turtles' true headings, we corrected the reconstructed tracks for current drift and found negligible differences between current-corrected and observed tracks within the gyre. Individual leatherback headings were remarkably consistent throughout the subtropical gyre, with turtles significantly oriented to the south-southeast. Adult leatherbacks of both sexes maintained similar mean headings and showed greater orientation precision overall. The consistent headings maintained by adult and subadult leatherbacks within the gyre suggest use of a common compass sense.

  11. Orientation behaviour of leatherback sea turtles within the North Atlantic subtropical gyre.

    PubMed

    Dodge, Kara L; Galuardi, Benjamin; Lutcavage, Molly E

    2015-04-01

    Leatherback sea turtles (Dermochelys coriacea) travel thousands of kilometres between temperate feeding and tropical breeding/over-wintering grounds, with adult turtles able to pinpoint specific nesting beaches after multi-year absences. Their extensive migrations often occur in oceanic habitat where limited known sensory information is available to aid in orientation. Here, we examined the migratory orientation of adult male, adult female and subadult leatherbacks during their open-ocean movements within the North Atlantic subtropical gyre by analysing satellite-derived tracks from fifteen individuals over a 2-year period. To determine the turtles' true headings, we corrected the reconstructed tracks for current drift and found negligible differences between current-corrected and observed tracks within the gyre. Individual leatherback headings were remarkably consistent throughout the subtropical gyre, with turtles significantly oriented to the south-southeast. Adult leatherbacks of both sexes maintained similar mean headings and showed greater orientation precision overall. The consistent headings maintained by adult and subadult leatherbacks within the gyre suggest use of a common compass sense. PMID:25761714

  12. Eolian inputs of lead to the North Pacific

    SciTech Connect

    Jones, C.E.; Halliday, A.N.; Rea, D.K.; Owen, R.M.

    2000-04-01

    The authors evaluate the importance of natural eolian Pb to the dissolved oceanic Pb budget by measuring the isotopic composition of Pb in 35 Holocene and late Quaternary sediment samples from the North Pacific and in 10 samples of Chinese loess. When the Pacific is divided into sediments provinces based on published {var_epsilon}{sub Nd} and sedimentological data, Pb from the central North Pacific tends to be the most radiogenic and homogeneous due to the dominance of eolian Chinese loess. Lead from the marginal North Pacific and the sparsely sampled regions south of 5{degree}N are less radiogenic and more variable owing to hemipelagic inputs from various volcanic arcs and older continental crust located around the Pacific Rim. {sup 208}Pb/{sup 204}Pb ratios provide the most distinctive provenance information due to the relatively high ratios in Chinese loess. The Chinese loess samples come from 3 localities and span up to 2 Myr of time. Acetic-acid leachate, bulk loess, and loess silicate fractions were analyzed separately. Leachate Pb is considerably less radiogenic than silicate Pb. The isotopic composition of the silicate component closely matches the sediment data from the central North Pacific, confirming the dominance of eolian loess in this region. The authors divided up a suite of published hydrogenous Pb-isotope data from the Pacific Ocean according to their locations within the three independently defined sediment provinces. These data define three distinct fields differentiated primarily by their {sup 206}Pb/{sup 204}Pb ratios, which increase going form the Central to Southern to Marginal provinces. This relationship with sediment province strongly suggests that natural eolian and probably hemipelagic inputs significantly impact the seawater Pb budget. Direct support for the dominance of eolian Chinese loess in the central North Pacific dissolved Pb budget comes from the close match between loess leachate Pb and the Central Province hydrogenous Pb data

  13. Regional variations of heavy metal concentrations in tissues of barnacles from the subtropical Pacific Coast of Mexico

    SciTech Connect

    Paez-Osuna, F.; Bojorquez-Leyva, H.; Ruelas-Inzunza, J.

    1999-07-01

    Concentrations of Cd, Cu, Cr, Fe, Mn, Ni, Ag, Pb, and Zn in soft and hard tissues of barnacles from eight sampling sites in six harbors on the subtropical Pacific Coast of Mexico were determined by atomic absorption spectrophotometry. Some inter-regional differences in metal concentrations, especially concerning Zn, Mn, Fe, Cd, and Pb, were identified. The lowest concentrations of Cu, Cr, Fe, and Ag were observed in the barnacle populations from Ceuta Lagoon, an uncontaminated site with rural agriculture and semi-intensive shrimp farms in the surroundings. Conversely, the highest concentrations of: (1) Zn, Cu, and Ag were found in the soft tissues of Balanus eburneus from Mazatlan piers; (2) Pb, Ni, and Cd in the soft tissue of Megabalanus coccopoma from Puerto Vallarta; (3) Fe in the hard tissue of Balanus sp. from Guaymas Harbour; and (4) Mn in the hard tissue of M. coccopoma from Mazatlan Harbour. Inter-comparison of the present data indicates that the soft (mainly Cd, Cu, Pb, and Zn) and the hard (mainly for Fe and Mn) tissues are useful in detecting areas of selected metallic contaminants. Barnacles such as B. eburneus, M. coccopoma, and Fistulobalanus dentivarians appear to be convenient biomonitors for identification of coastal waters exposed to Cd, Pb, Cu, Zn, Ni, Mn, Fe, and Ag in the American region of the subtropical Pacific.

  14. Persistent millennial-scale climate variability in the eastern tropical North Pacific over the last two glacial cycles

    NASA Astrophysics Data System (ADS)

    Arellano-Torres, Elsa; Ganeshram, Raja S.; Pichevin, Laetitia E.; Salas-de-Leon, David Alberto

    2015-06-01

    High-resolution sediment records from the eastern tropical North Pacific (ETNP) spanning the last ~240 ka B.P. were studied to document the nature of millennial-scale climatic events in the tropical Pacific and to investigate teleconnection mechanisms. We present organic carbon (%OC) and diffuse spectral reflectivity records as indicative of upwelling and productivity changes off NW Mexico over the middle to late Pleistocene. The new productivity records document the persistence of abrupt millennial-scale changes over the last two glacial cycles. Detailed spectral and wavelet time series analyses show the predominance of longer climatic cycles (2-6 ka) during the last and the penultimate glacial periods. The persistence of millennial variability during the penultimate glacial, in absence of large ice rafted debris events in the North Atlantic, suggests that freshwater input through ice sheet dynamics is not essential for millennial-scale climate variability. Given the worldwide emerging picture of remarkable similar millennial-scale records over long time periods, we suggest that the pacing of this climate variability may represent a natural resonance in the climate system, amplified by a tightly coupled oceanic and atmospheric teleconnection processes. We present a schematic scenario of millennial-scale climate change depicting the role of the tropical Pacific in this global teleconnection system by linking productivity and upwelling changes in the ETNP with shifts in the position of the Intertropical Convergence Zone and the strength of the subtropical North Pacific High.

  15. Direct observation of subtropical mode water circulation in the western North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Fratantoni, David M.; Kwon, Young-Oh; Hodges, Benjamin A.

    2013-07-01

    Eighteen Degree Water (EDW) is the dominant subtropical mode water of the North Atlantic subtropical gyre and is hypothesized as an interannual reservoir of anomalous heat, nutrients and CO2. Although isolated beneath the stratified upper-ocean at the end of each winter, EDW may re-emerge in subsequent years to influence mixed layer properties and consequently air-sea interaction and primary productivity. Here we report on recent quasi-Lagrangian measurements of EDW circulation and stratification in the western subtropical gyre using an array of acoustically-tracked, isotherm-following, bobbing profiling floats programmed to track and intensively sample the vertically homogenized EDW layer and directly measure velocity on the 18.5 °C isothermal surface. The majority of the CLIVAR Mode Water Dynamics Experiment (CLIMODE) bobbers drifted within the subtropical gyre for 2.5-3.5 years, many exhibiting complex looping patterns indicative of an energetic eddy field. Bobber-derived Lagrangian integral time and length scales (3 days, 68 km) associated with motion on 18.5 °C were consistent with previous measurements in the Gulf Stream extension region and fall between previous estimates at the ocean surface and thermocline depth. Several bobbers provided evidence of long-lived submesoscale coherent vortices associated with substantial EDW thickness. While the relative importance of such vortices remains to be determined, our observations indicate that these features can have a profound effect on EDW distribution. EDW thickness (defined using a vertical temperature gradient criterion) exhibits seasonal changes in opposition to a layer bounded by the 17 °C and 19 °C isotherms. In particular, EDW thickness is generally greatest in winter (as a result of buoyancy-forced convection), while the 17°-19 °C layer is thickest in summer consistent with seasonal Ekman pumping. Contrary to previous hypotheses, the bobber data suggest that a substantial fraction of subducted EDW

  16. Enhanced Particulate Organic Carbon Export at Eddy Edges in the Oligotrophic Western North Pacific Ocean

    PubMed Central

    Shih, Yung-Yen; Hung, Chin-Chang; Gong, Gwo-Ching; Chung, Wan-Chen; Wang, Yu-Huai; Lee, I-Huan; Chen, Kuo-Shu; Ho, Chuang-Yi

    2015-01-01

    Mesoscale eddies in the subtropical oligotrophic ocean are ubiquitous and play an important role in nutrient supply and oceanic primary production. However, it is still unclear whether these mesoscale eddies can efficiently transfer CO2 from the atmosphere to deep waters via biological pump because of the sampling difficulty due to their transient nature. In 2007, particulate organic carbon (POC) fluxes, measured below the euphotic zone at the edge of warm eddy were 136–194 mg-C m−2 d−1 which was greatly elevated over that (POC flux = 26–35 mg-C m−2 d−1) determined in the nutrient-depleted oligotrophic waters in the Western North Pacific (WNP). In 2010, higher POC fluxes (83–115 mg-C m−2 d−1) were also observed at the boundary of mesoscale eddies in the WNP. The enhanced POC flux at the edge of eddies was mainly attributed to both large denuded diatom frustules and zooplankton fecal pellets based on scanning electron microscopy (SEM) examination. The result suggests that mesoscale eddies in the oligotrophic waters in the subtropical WNP can efficiently increase the oceanic carbon export flux and the eddy edge is a crucial conduit in carbon sequestration to deep waters. PMID:26171611

  17. Atmospheric peroxides over the North Pacific during IOC 2002 shipboard experiment.

    PubMed

    Kim, Young-Mi; Lee, Meehye; Chang, Wonil; Lee, Gangwoong; Kim, Kyung-Ryul; Kato, Shungo

    2007-11-01

    Atmospheric hydrogen peroxide and methyl hydroperoxide were determined onboard the Melville over the North Pacific from Osaka to Honolulu during May-June 2002. The concentrations of H(2)O(2) and CH(3)OOH increased from 0.64+/-0.57 ppbv and 0.27+/-0.59 ppbv in subpolar region (30-50 degrees N) to 1.96+/-0.95 ppbv and 1.56+/-1.3 ppbv in subtropical region (24-30 degrees N). The increase in concentrations towards the Equator was more pronounced for CH(3)OOH than H(2)O(2). In contrast, the levels of O(3) and CO were decreased at lower latitudes as air mass was more aged, denoted by the ratios of C(2)H(2)/CO and C(3)H(8)/C(2)H(6). CH(3)OOH concentrations showed a clear diurnal variation with a maximum around noon and minimum before sunrise. Frequently, the concentrations of peroxides remained over 1 ppbv in the dark and even gradually increased after sunset. In addition, the ratios of C(2)H(4)/C(2)H(6) and C(3)H(6)/C(3)H(8) were increased in aged subtropical air, which implies that these alkenes were emitted from the ocean surface. As a result, the reaction of these biogenic alkenes with O(3) was suggested to be a potential source for peroxides in aged marine air at lower latitudes.

  18. Diversity and distribution of microbial eukaryotes in the deep tropical and subtropical North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Morgan-Smith, Danielle; Clouse, Melissa A.; Herndl, Gerhard J.; Bochdansky, Alexander B.

    2013-08-01

    Employing a combination of 4',6-diamidino-2-phenylindole and fluorescein isothiocyanate (DAPI-FITC) staining and catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH), we distinguished a variety of taxonomic and morphological types of eukaryotic microbes in the central and deep water masses of the tropical and subtropical North Atlantic Ocean. Samples were taken along a transect across the tropical Atlantic, along the equatorial upwelling and into the West-African upwelling region. Samples were collected as deep as 7000 m in the Romanche Fracture Zone within the Mid-Atlantic Ridge. Approximately 50-70% of FISH-identified eukaryotes in deep water masses belong to one of seven groups: kinetoplastids, labyrinthulomycetes, fungi, diplonemids, group II alveolates, MAST 4 (stramenopiles), and an unidentified organism with a peculiar nuclear morphology. A smaller percentage of total eukaryotes was identified in the Central Water, especially in the oxygen minimum zone, than in deep water masses. CARD-FISH probes designed to identify broad taxonomic groups revealed kinetoplastids and fungi were more abundant than noted in previous studies employing 18S rRNA gene clone libraries. Group II alveolates, in contrast, were much less prevalent than previously reported. On a second survey, eukaryotic microbes were enumerated in the deep-sea basins below the North Atlantic subtropical gyre including the Vema Fracture Zone, which is another prominent trench in the Mid-Atlantic Ridge. The abundance of eukaryotes and chlorophyll concentrations were significantly different between the two cruises, which covered very different hydrographic regimes with associated high and low levels of primary production, respectively.

  19. Subtropical iceberg scours: Tracking the path of meltwater in the deglacial North Atlantic

    NASA Astrophysics Data System (ADS)

    Hill, J. C.; Condron, A.

    2015-12-01

    Over 700 individual iceberg scours have been identified in seafloor bathymetry spanning the southern U.S. Atlantic margin, from Cape Hatteras, North Carolina to the Florida Keys, in water depths from 170-380m. These iceberg scours represent the plowing path of iceberg keels transported southward along the margin in a cold, coastal boundary current derived from the Laurentide Ice Sheet. Despite limited regional multibeam bathymetry data, the scours are traceable along the seafloor for >30 km and exhibit characteristic morphology of iceberg keel marks documented along glaciated continental margins. Many of the scours are flanked by lateral berms that are several meters high and often terminate in semi-circular pits ringed by several meter high ridges (i.e. grounding pits or iceberg plow ridges). The scours decrease in size and abundance moving southward, in accordance with increased iceberg melting farther from the ice calving margin. For example, the scours offshore of South Carolina (~32.5°N) are ~10-100m wide and incised 10-20m into the sediment, whereas scours off the Florida margin (31°N- 24.5°N) are narrower (10-50m wide) and incised 2-5m into the sea floor. Icebergs at these subtropical latitudes would likely have been comparable in size (up 300 m thick) to those calving from the modern-day Greenland Ice Sheet margin. Results from numerical simulations using MITgcm, a high-resolution, eddy-permitting, coupled ice-ocean model configured for the LGM suggest that cold, freshwater and small (≤90m thick) icebergs could have seasonally drifted to South Carolina, but iceberg transport to southern Florida requires much larger (5Sv) meltwater floods to overcome the northward flowing Gulf Stream. These meltwater flood events would most likely have been short-lived (<1 yr), but may have diverted a significant volume of freshwater away from the subpolar regions into the subtropical North Atlantic.

  20. Mapping the Origins of Chromophoric Dissolved Organic Matter in the North Atlantic Subtropical Gyre

    NASA Astrophysics Data System (ADS)

    McDonald, N.; Logendran, V.; Evans, D. G.; Peters, A.; Nelson, N. B.

    2010-12-01

    The chromophoric or "light-absorbing" fraction of dissolved organic matter plays a significant role in the regulation of the underwater light field. In the North Atlantic subtropical gyre, it's origins vary, and include contributions from both terrestrial and marine sources. Furthermore, within the fraction of marine-origin CDOM, there are distinctions between that of local origin and that coming from other regions via transport through water masses or through atmospheric deposition. As the optical and chemical properties of CDOM depend largely on its source, an analysis of its origins could lead to a better understanding of processes in the North Atlantic subtropical gyre. For this analysis, we have used absorption data from CDOM measurements collected repeatedly for a number of years at the BATS site in the Sargasso Sea. Samples have been collected at the same series of depths ranging from surface waters to 4200 meters. The samples were analyzed using a dual beam spectrophotometer to obtain absorption spectra. The slope parameter, S, provides more in depth information about the source of CDOM than does the absorption spectra alone, and thus we have used it as well as the slope ratio, Sr, for differentiating between different types of CDOM. Slope ratios were obtained by selecting portions of the spectral slope at wavelength ranges, which have been found to be indicative of CDOM originating from a particular source. For example, it can be used to distinguish marine CDOM formed locally in the Sargasso Sea from that which has been formed further north in the Atlantic and then subducted and transported to the Sargasso. There are various other methods for ascertaining the sources of CDOM, and the most comprehensive model for CDOM in the North Atlantic is likely obtained using a combination of all of them. Excitation-emission matrix spectra (EEMS) have been performed on samples from the same site in the Sargasso Sea to corroborate findings from the S and Sr analyses

  1. Northerly surface winds over the eastern North Pacific Ocean in spring and summer

    USGS Publications Warehouse

    Taylor, S.V.; Cayan, D.R.; Graham, N.E.; Georgakakos, K.P.

    2008-01-01

    Persistent spring and summer northerly surface winds are the defining climatological feature of the western coast of North America, especially south of the Oregon coast. Northerly surface winds are important for upwelling and a vast array of other biological, oceanic, and atmospheric processes. Intermittence in northerly coastal surface wind is characterized and wind events are quantitatively defined using coastal buoy data south of Cape Mendocino on the northern California coast. The defined wind events are then used as a basis for composites in order to explain the spatial evolution of various atmospheric and oceanic processes. Wind events involve large-scale changes in the three-dimensional atmospheric circulation including the eastern North Pacific subtropical anticyclone and southeast trade winds. Composites of QSCAT satellite scatterometer wind estimates from 1999 to 2005 based on a single coastal buoy indicate that wind events typically last 72-96 h and result in anomalies in surface wind and Ekman pumping that extend over 1000 kin from the west coast of North America. It may be useful to consider ocean circulation and dependent ecosystem dynamics and the distribution of temperature, moisture, and aerosols in the atmospheric boundary layer in the context of wind events defined herein. Copyright 2008 by the American Geophysical Union.

  2. Variation of the Tropical Upper-tropospheric Trough and Its Linkage to the Asian-Pacific-North American Summer Climate

    NASA Astrophysics Data System (ADS)

    Deng, Kaiqiang; Yang, Song

    2016-04-01

    The tropical upper-tropospheric trough (TUTT) is one of the most prominent features in Northern Hemisphere (NH) summer, which peaks at 200-150 hPa in July and August. It is found that the TUTT varies largely from year to year, which indicates that the TUTT may exert great effects on the NH summer climate. In order to explore the causes that lead to the interannual variations of the TUTT, an area-weighted empirical orthogonal function decomposition analysis was applied to. The first mode reflects the northeastward-southwestward displacement of the TUTT, which is significantly related to the planetary wave originating from the Indo-western Pacific during a developing La Niña. The second mode presents the intensity change of the TUTT, which is attributed to the enhanced convection over the central Pacific where the anomalous warming sea surface temperature is appearing. The third mode shows the northwestward-southeastward displacement of the TUTT, which is correlated well with the north-south direction shift of east Asian westerly jet. Anomalous warming over the midlatitudes and cooling over the subtropics suggests a decreased meridional temperature gradient, which results in the northward displacement of westerly jet. The variations of TUTT's location and strength have distinct effects on the variation of South Asian high, the northwestern Pacific subtropical high, and the Mexican high, which subsequently modulate the climate anomalies in different regions.

  3. Tropospheric ozone over the North Pacific from ozonesonde observations

    NASA Astrophysics Data System (ADS)

    Oltmans, S. J.; Johnson, B. J.; Harris, J. M.; Thompson, A. M.; Liu, H. Y.; Chan, C. Y.; VöMel, H.; Fujimoto, T.; Brackett, V. G.; Chang, W. L.; Chen, J.-P.; Kim, J. H.; Chan, L. Y.; Chang, H.-W.

    2004-08-01

    As part of the Transport and Chemical Evolution over the Pacific (TRACE-P) mission, ozonesondes were used to make ozone vertical profile measurements at nine locations in the North Pacific. At most of the sites there is a multiyear record of observations. From locations in the western Pacific (Hong Kong; Taipei; Jeju Island, Korea; and Naha, Kagoshima, Tsukuba, and Sapporo, Japan), a site in the central Pacific (Hilo, Hawaii), and a site on the west coast of the United States (Trinidad Head, California) both a seasonal and event specific picture of tropospheric ozone over the North Pacific emerges. Ozone profiles over the North Pacific generally show a prominent spring maximum throughout the troposphere. This maximum is tied to the location of the jet stream and its influence on stratosphere-troposphere exchange and the increase in photochemical ozone production through the spring. Prominent layers of enhanced ozone in the middle and upper troposphere north of about 30°N seem to be more closely tied to stratospheric intrusions while biomass burning leads to layers of enhanced ozone in the lower and upper troposphere at Hong Kong (22°N) and Taipei (25°N). The lower free tropospheric layers at Hong Kong are associated with burning in SE Asia, but the upper layer may be associated with either equatorial Northern Hemisphere burning in Africa or SE Asian biomass burning. In the boundary layer at Taipei very high mixing ratios of ozone were observed that result from pollution transport from China in the spring and local urban pollution during the summer. At the ozonesonde site near Tokyo (Tsukuba, 36°N) very large enhancements of ozone are seen in the boundary layer in the summer that are characteristic of urban air pollution. At sites in the mid and eastern Pacific the signature of transport of polluted air from Asia is not readily identifiable from the ozonesonde profile. This is likely due to the more subtle signal and the fact that from the ozone profile and

  4. The biogeography of the North Pacific right whale ( Eubalaena japonica)

    NASA Astrophysics Data System (ADS)

    Gregr, Edward J.; Coyle, Kenneth O.

    2009-03-01

    The eastern North Pacific population of right whales ( Eubalaena japonica) is among the most endangered whale populations, with an estimated size of only 10s of individuals. The effectiveness of measures (e.g., protected areas, abundance surveys) intended to promote recovery of this population will be enhanced by understanding its distribution, habitat use, and habitat characteristics. In order to facilitate such understanding, we summarized relevant right whale biology, reviewed the life history of their zooplankton prey species, and related North Pacific oceanography to the production, distribution, and concentration of these prey at three scales of variability. We discuss how ocean processes may drive zooplankton distribution and concentration, and present hypotheses about how prey patches suitable for right whale foraging might be formed. Such hypotheses, combined with available distributional data and descriptions of the ocean environment, would be suitable for predicting potential right whale foraging habitat.

  5. Current inventory of anthropogenic carbon dioxide in the North Pacific

    SciTech Connect

    Cline, J.D.; Feely, R.A.; Kelly-Hansen, K.; Gendron, J.F.; Wisegarver, D.P.

    1985-01-01

    The atmospheric increase of carbon dioxide is the result of the burning of fossil fuels and massive deforestation currently underway. Since 1958, the atmosphere CO/sub 2/ concentration has risen from about 315 ppm to about 343 ppm. The major repositories for anthropogenic CO/sub 2/ are the oceans and the atmosphere. The distributions of freon-11, as a surrogate tracer, have been combined with precise measurements of total carbon dioxide, total alkalinity oxygen, nutrient and hydrography in order to estimate the amount of excess CO/sub 2/ in the subarctic water of the north Pacific gyre. Calculations indicate that approximately 4 x 10 to the 1B power G of excess carbon, or about 2% of the total estimated fossil-fuel derived carbon input now resides in the mixed layer and thermocline waters of the north Pacific gyre.

  6. The Relation between Sea Surface Temperature at the Subtropical South-Central Pacific and Precipitation in Southeastern South America.

    NASA Astrophysics Data System (ADS)

    Barros, Vicente R.; Silvestri, Gabriel E.

    2002-02-01

    This paper deals with the relationship between the interannual variability of sea surface temperature (SST) and its associated atmospheric circulation and rainfall variability over southeastern South America (SSA), namely the subtropical region east of the Andes between 20° and 40°S, during the austral spring. Rainfall in SSA and SST interannual variability is studied using canonical correlation analysis. The first two modes show the well-known warm-wet and cold-dry pattern between the equatorial SST and rainfall over most of this part of the world. However, SST in the equatorial regions does not modulate rainfall variability among El Niño (EN) years or among La Niña (LN) years. On the other hand, it does modulate this variability between EN and LN cases as a whole and among neutral cases indicating that the SSA rainfall response to equatorial Pacific SST is not linear over the observed SST range, having no dependence on the extremes of this range. In contrast, among EN events, SST in the subtropical south-central Pacific (SSCP) modulates the seasonal rainfall over most of SSA. Also, when all the years are considered, this SST has a correlation with precipitation of magnitude similar to those corresponding to the SST in EN regions. Consistent with this, the circulation field has enhanced cyclonic (anticyclonic) advection over subtropical SSA when SST in the SSCP is cold (warm).SSTs in EN-3 or EN-3.4 regions and in the SSCP are negatively correlated, but their correlation is practically zero when only EN cases or only neutral cases are considered, and very small in LN cases. This allows a stratification analysis composing cases according to different SSTs in EN-3 and EN-3.4 regions with almost constant SST in the SSCP and similarly according to different SST in the SSCP with approximately constant SST in EN regions. The composite difference fields with constant equatorial SST and with constant SST in the SSCP have a wave train in the Pacific similar to the ENSO

  7. Phanerozoic tectonic evolution of the Circum-North Pacific

    USGS Publications Warehouse

    Nokleberg, Warren J.; Parfenov, Leonid M.; Monger, James W.H.; Norton, Ian O.; Khanchuk, Alexander I.; Stone, David B.; Scotese, Christopher R.; Scholl, David W.; Fujita, Kazuya

    2000-01-01

    The Phanerozoic tectonic evolution of the Circum-North Pacific is recorded mainly in the orogenic collages of the Circum-North Pacific mountain belts that separate the North Pacific from the eastern part of the North Asian Craton and the western part of the North American Craton. These collages consist of tectonostratigraphic terranes that are composed of fragments of igneous arcs, accretionary-wedge and subduction-zone complexes, passive continental margins, and cratons; they are overlapped by continental-margin-arc and sedimentary-basin assemblages. The geologic history of the terranes and overlap assemblages is highly complex because of postaccretionary dismemberment and translation during strike-slip faulting that occurred subparallel to continental margins.We analyze the complex tectonics of this region by the following steps. (1) We assign tectonic environments for the orogenic collages from regional compilation and synthesis of stratigraphic and faunal data. The types of tectonic environments include cratonal, passive continental margin, metamorphosed continental margin, continental-margin arc, island arc, oceanic crust, seamount, ophiolite, accretionary wedge, subduction zone, turbidite basin, and metamorphic. (2) We make correlations between terranes. (3) We group coeval terranes into a single tectonic origin, for example, a single island arc or subduction zone. (4) We group igneous-arc and subduction- zone terranes, which are interpreted as being tectonically linked, into coeval, curvilinear arc/subduction-zone complexes. (5) We interpret the original positions of terranes, using geologic, faunal, and paleomagnetic data. (6) We construct the paths of tectonic migration. Six processes overlapping in time were responsible for most of the complexities of the collage of terranes and overlap assemblages around the Circum-North Pacific, as follows. (1) During the Late Proterozoic, Late Devonian, and Early Carboniferous, major periods of rifting occurred along

  8. North Pacific Mesoscale Coupled Air-Ocean Simulations Compared with Observations

    SciTech Connect

    Koracin, Darko; Cerovecki, Ivana; Vellore, Ramesh; Mejia, John; Hatchett, Benjamin; McCord, Travis; McLean, Julie; Dorman, Clive

    2013-04-11

    Executive summary The main objective of the study was to investigate atmospheric and ocean interaction processes in the western Pacific and, in particular, effects of significant ocean heat loss in the Kuroshio and Kuroshio Extension regions on the lower and upper atmosphere. It is yet to be determined how significant are these processes are on climate scales. The understanding of these processes led us also to development of the methodology of coupling the Weather and Research Forecasting model with the Parallel Ocean Program model for western Pacific regional weather and climate simulations. We tested NCAR-developed research software Coupler 7 for coupling of the WRF and POP models and assessed its usability for regional-scale applications. We completed test simulations using the Coupler 7 framework, but implemented a standard WRF model code with options for both one- and two-way mode coupling. This type of coupling will allow us to seamlessly incorporate new WRF updates and versions in the future. We also performed a long-term WRF simulation (15 years) covering the entire North Pacific as well as high-resolution simulations of a case study which included extreme ocean heat losses in the Kuroshio and Kuroshio Extension regions. Since the extreme ocean heat loss occurs during winter cold air outbreaks (CAO), we simulated and analyzed a case study of a severe CAO event in January 2000 in detail. We found that the ocean heat loss induced by CAOs is amplified by additional advection from mesocyclones forming on the southern part of the Japan Sea. Large scale synoptic patterns with anomalously strong anticyclone over Siberia and Mongolia, deep Aleutian Low, and the Pacific subtropical ridge are a crucial setup for the CAO. It was found that the onset of the CAO is related to the breaking of atmospheric Rossby waves and vertical transport of vorticity that facilitates meridional advection. The study also indicates that intrinsic parameterization of the surface fluxes

  9. Trends in Western North Pacific Tropical Cyclone Intensity

    NASA Astrophysics Data System (ADS)

    Wu, Man-Chi; Yeung, Kai-Hing; Chang, Wen-Lam

    2006-11-01

    Using the tropical cyclone best track data from the U.S. Department of Defense's Joint Typhoon Warning Center (JTWC), Webster et al. found that between the two consecutive 15-year periods of 1975-1989 and 1990-2004, the percentage of typhoons in the western North Pacific meeting the definition of categories 4 and 5 on the Saffir-Simpson Hurricane Scale has increased from 25% to 41% of all typhoons in that ocean basin

  10. Decadal Drought and Wetness Reconstructed for Subtropical North America in the Mexican Drought Atlas

    NASA Astrophysics Data System (ADS)

    Burnette, D. J.; Stahle, D. W.; Cook, E. R.; Villanueva Diaz, J.; Griffin, D.; Cook, B.

    2014-12-01

    A new drought atlas has been developed for subtropical North America, including the entire Republic of Mexico. This Mexican Drought Atlas (MXDA) is based on 251 tree-ring chronologies, including 82 from Mexico and another 169 from the southern U.S. and western Guatemala. Point-by-point principal components regression was used to reconstruct the self-calibrating Palmer Drought Severity Index (PDSI) for June-August. Calibration and verification statistics were improved over what was previously possible with the North American Drought Atlas, which was based on fewer chronologies only in Mexico. The MXDA will be served on the web with analytical tools for composite, correlation, and congruence analyses. The new PDSI reconstructions provide a more detailed estimation of decadal moisture regimes over the past 2000 years, but are most robust after 1400 AD, when several chronologies are available across Mexico. Droughts previously identified in a subset of chronologies are confirmed and their spatial impact quantified in the new reconstructions. This includes the intense drought of the mid-15th Century described in Aztec legend, the 16th Century megadrought, and "El Año del Hambre", one of the worst famines in Mexican history. We also use the best replicated portion of the MXDA in the 18th and 19th Centuries to reconstruct moisture anomalies during key time periods of Mexican turmoil (e.g., the Mexican War of Independence).

  11. Longitudinal variability of organic nutrients in the North Atlantic subtropical gyre

    NASA Astrophysics Data System (ADS)

    Landolfi, A.; Dietze, H.; Volpe, G.

    2016-05-01

    We combine modelled timescales of ocean circulation with satellite-retrieved and in situ biogeochemical observations collected in spring along 24.5°N in the subtropical North Atlantic. Longitudinal gradients in the distribution of dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) and in other biogeochemical parameters are associated with the longitudinal variability in physical forcing and in the eastward increase of the timescale of advective transport. The western (West of 70°W) and eastern (East of 30°W) margins of the subtropical gyre appear influenced by the productive regions of the Gulf Stream and upwelling zones off Africa, respectively. Within the oligotrophic zone between 70 and 31°W, at approximately 46°W there is a change in the nutrient-controlling factors from the western ultraoligotrophic with barely any seasonal cycle to an eastern oligotrophic environment with a more intense mixed layer dynamics. The allochthonous supply of semilabile-DOP may be important in the western sector of the oligotrophic gyre (approx. 70-46°W) where, together with the combination of shallow mixed layers, almost permanent stratification and high water temperatures create a niche for the growth of diazotrophs, which we detect from space. Turnover estimates exceeding 3 yr suggest that even reactive fractions of DON are unlikely to be a significant N source. In the eastern sector of the oligotrophic gyre (46-31°W), transit timescales longer than 3 years suggest that the allochthonous supply of the semilabile DOP is negligible due to its exhaustion. Here, an intense mixed layer dynamics favours nutrient supply from below the mixed layer. We speculate that longitudinal variability in physical forcing and gradients in the timescale of advection, combined with distinct turnover timescales of reactive fractions of DON and DOP, drive diverse phytoplankton assemblages and surface nitrogen fixation gradients across our region of investigation.

  12. Venereal diseases in the islands of the North Pacific.

    PubMed Central

    Willcox, R R

    1980-01-01

    Apart from the Japanese islands, and those of Karabati (lately Gilbert Islands), which lie just north of the equator, the islands of the northern Pacific Ocean are either American owned or otherwise administered. Even the Japanese islands were controlled by the USA for varying numbers of years after the second world war. Venereal disease statistics from Guam, the Trust Territory of the Pacific Islands, and the Gilbert Islands have been collated by the South Pacific Commission and will be presented in a second paper. Those from the Hawaiian Islands (the fiftieth state of the USA) are published by the United States Public Health Service and include those from Honolulu, the capital. While the rates per 100 000 for both syphilis and gonorrhoea are lower than those for the USA as a whole, the trends since 1970 have been less satisfactory in the state of Hawaii than for the whole of the United States. While the disturbing increasing incidence of primary and secondary syphilis was checked in 1977, that of gonorrhoea has continued to rise. The number of cases of gonorrhoea also increased in Guam and the Trust Territory of the Pacific Islands but there has been a recent fall from earlier peak figures. The pattern of venereal disease in the most developed Pacific islands is thus gradually approaching what may be expected elsewhere in modern western society and it would seem logical to expect that this trend will continue. PMID:6893564

  13. Are Greenhouse Gases Changing ENSO Precursors in the Western North Pacific?

    SciTech Connect

    Wang, S-Y; Heureux, Michelle L.; Yoon, Jin-Ho

    2013-09-01

    Using multiple observational and modeling datasets, we document a strengthening relationship between boreal winter sea surface temperature anomalies (SSTA) in the western North Pacific (WNP) and the development of the El Nino-Southern Oscillation (ENSO) one year later. The increased WNP-ENSO association emerged in the mid 20th century and has grown through the present, reaching correlation coefficients as high as ~0.70 in recent decades. Fully coupled climate experiments with the Community Earth System Model (CESM) replicate the WNP-ENSO association and indicate that greenhouse gases (GHG) are largely responsible for the observed increase. We speculate that shifts in the location and amplitudes of positive SST trends in the subtropical-tropical western Pacific impacts the low-level circulation so that WNP variability is increasingly influencing the development of ENSO one year later. A strengthened GHG-driven relationship between the WNP and ENSO provides an example of how anthropogenic climate change can potentially improve the skill of intraseasonal-to-interannual climate prediction.

  14. Inter-comparison of deep convection over the Tibetan Plateau-Asian Monsoon Region and subtropical North America in boreal summer using CloudSat/CALIPSO data

    NASA Astrophysics Data System (ADS)

    Luo, Y.; Zhang, R.; Qian, W.; Luo, Z.

    2010-12-01

    Deep convection at the Tibetan Plateau-Southern Asian Monsoon Region (TP-SAMR) is analyzed using CloudSat and CALIPSO data for the boreal summer season (June-August) from 2006 to 2009. Three sub-regions - the Tibetan Plateau (TP), southern slope of the Plateau (PSS), and southern Asian monsoon region (SAMR) - are defined and deep convection properties are compared among these sub-regions. To cast them in a broader context, we also bring in four additional regions that bear some similarity to the TP-SAMR: East Asia (EA), tropical northwestern Pacific (NWP), west and east North America (WNA, ENA). The principal findings are as follows: 1) Compared to the other two sub-regions of the TP-SAMR, deep convection at the TP is shallower, less frequent, and embedded in smaller-size convection systems, but the cloud tops are more densely packed. These characteristics of deep convection at the TP are closely related to the significantly lower level of neutral buoyancy (LNB) and much drier atmosphere. 2) In a broader context where all seven regions are brought together, deep convection at the two tropical regions (NWP and SAMR; mostly over ocean) is similar in many regards. Similar conclusion can be drawn among the four subtropical continental regions (TP, EA, WNA, and ENA). However, tropical oceanic and subtropical land regions present some significant contrasts: deep convection in the latter region occurs less frequently, has lower cloud tops but comparable or slightly higher tops of large radar echo, and is embedded in smaller systems. The cloud tops of the subtropical land regions are generally more densely packed. Hence, the difference between TP and SAMR is more of a general contrast between subtropical land regions and tropical oceanic regions during the boreal summer. 3) Deep convection at the PSS possesses some uniqueness of its own because of the distinctive terrain (slopes) and moist low-level monsoon flow. 4) Results from comparison between the daytime and the

  15. Intercomparison of Deep Convection over the Tibetan Plateau-Asian Monsoon Region and Subtropical North America in Boreal Summer Using CloudSat/CALIPSO Data

    NASA Astrophysics Data System (ADS)

    Luo, Y.; Zhang, R.; Qian, W.; Luo, Z.

    2012-04-01

    Deep convection in the Tibetan Plateau-southern Asian monsoon region (TP-SAMR) is analyzed using CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data for the boreal summer season (June-August) from 2006 to 2009. Three subregions are defined—the TP, the southern slope of the plateau (PSS), and the SAMR—and deep convection properties (such as occurrence frequency, internal vertical structure, system size, and local environment) are compared among these subregions. To cast them in a broader context, four additional regions that bear some similarity to the TP-SAMR are also discussed: East Asia (EA), tropical northwestern Pacific (NWP), and western and eastern North America (WNA and ENA, respectively). The principal findings are as follows: 1) Compared to the other two subregions of the TP-SAMR, deep convection over the TP is shallower, less frequent, and embedded in smaller-size convection systems, but the cloud tops are more densely packed. These characteristics of deep convection over the TP are closely related to the unique local environment, namely, a significantly lower level of neutral buoyancy (LNB) and much drier atmosphere. 2) In a broader context in which all seven regions are brought together, deep convection in the two tropical regions (NWP and SAMR; mostly over ocean) is similar in many regards. A similar conclusion can be drawn among the four subtropical continental regions (TP, EA, WNA, and ENA). However, tropical oceanic and subtropical land regions present some significant contrasts: deep convection in the latter region occurs less frequently, has lower cloud tops but comparable or slightly higher tops of large radar echo (e.g., 0 and 10 dBZ), and is embedded in smaller systems. The cloud tops of the subtropical land regions are generally more densely packed.Hence, the difference between the TP and SAMRismore of a general contrast between subtropical land regions and tropical oceanic regions during the

  16. Observed recent trends in tropical cyclone rainfall over the North Atlantic and the North Pacific

    NASA Astrophysics Data System (ADS)

    Lau, William K. M.; Zhou, Y. P.

    2012-02-01

    In this study, we use Tropical Rainfall Measurement Mission and Global Precipitation Climatology Project rainfall data together with historical storm track records to examine the trend of tropical cyclone (TC) rainfall in the North Atlantic and the northeast and northwest Pacific during two recent decades (1988-1997 and 1998-2007). We find that there is an approximate linear relationship between TC rain (defined as accumulated total rainfall along storm tracks) and storm intensity as classified by the Saffir-Simpson scheme. During the data period, total TC rain has trended upward at a rate of 23.8% ± 23.5% per decade over the North Atlantic but downward with a rate of 25.1% ± 19.7% per decade over the northeast Pacific. Over the northwest Pacific, there is a reduction in TC rain of approximately 20.9% ± 13.5% per decade, possibly associated with a strong interdecadal-scale oscillation. Storm characteristics such as duration and TC rain energy per storm (EPS) remain unchanged for the North Atlantic and the northeast Pacific. For the northwest Pacific, a 28% ± 18% reduction in EPS from the first decade (1988-1997) to the second decade (1998-2007) is found with the track data from the Joint Typhoon Warning Center. Analyses of the probability distribution function of TC rain show that there is an overall increase in TC frequency across the entire TC rainfall spectrum over the North Atlantic but an overall decrease for the northeast Pacific. In the northwest Pacific, we find a redistribution in EPS with decreased frequency in heavy-rain storms and increased frequency in light-rain storms. Overall, trends in TC rain in the different ocean basins are consistent with long-term relative changes in the ambient large-scale sea surface temperature and vertical wind shear and, to a lesser extent, tropical cyclone Maximum Potential Intensity.

  17. Impact of the Interdecadal Pacific Oscillation on Tropical Cyclone Activity in the North Atlantic and Eastern North Pacific.

    PubMed

    Li, Wenhong; Li, Laifang; Deng, Yi

    2015-01-01

    Tropical cyclones (TCs) are among the most devastating weather systems affecting the United States and Central America (USCA). Here we show that the Interdecadal Pacific Oscillation (IPO) strongly modulates TC activity over the North Atlantic (NA) and eastern North Pacific (eNP). During positive IPO phases, less (more) TCs were observed over NA (eNP), likely due to the presence of stronger (weaker) vertical wind shear and the resulting changes in genesis potential. Furthermore, TCs over NA tend to keep their tracks more eastward and recurve at lower latitudes during positive IPO phases. Such variations are largely determined by changes in steering flow instead of changes in genesis locations. Over the eNP, smaller track variations are observed at different IPO phases with stable, westward movements of TCs prevailing. These findings have substantial implications for understanding decadal to inter-decadal fluctuations in the risk of TC landfalls along USCA coasts. PMID:26205462

  18. Impact of the Interdecadal Pacific Oscillation on Tropical Cyclone Activity in the North Atlantic and Eastern North Pacific

    PubMed Central

    Li, Wenhong; Li, Laifang; Deng, Yi

    2015-01-01

    Tropical cyclones (TCs) are among the most devastating weather systems affecting the United States and Central America (USCA). Here we show that the Interdecadal Pacific Oscillation (IPO) strongly modulates TC activity over the North Atlantic (NA) and eastern North Pacific (eNP). During positive IPO phases, less (more) TCs were observed over NA (eNP), likely due to the presence of stronger (weaker) vertical wind shear and the resulting changes in genesis potential. Furthermore, TCs over NA tend to keep their tracks more eastward and recurve at lower latitudes during positive IPO phases. Such variations are largely determined by changes in steering flow instead of changes in genesis locations. Over the eNP, smaller track variations are observed at different IPO phases with stable, westward movements of TCs prevailing. These findings have substantial implications for understanding decadal to inter-decadal fluctuations in the risk of TC landfalls along USCA coasts. PMID:26205462

  19. Constraining the Sources of Neodymium in the North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Goldstein, S. L.; Pena, L.; Hayes, C. T.; Anderson, R. F.; Gersonde, R.

    2015-12-01

    The high Nd isotope ratios of North Pacific Deep Water (NPDW, ɛNd ~ -4) have been difficult to reconcile with the eolian inputs as reflected in surface waters (e.g. Jones et al. 2008 EPSL), which have much lower ɛNd (~ -10), indicating potential addition of volcanic component. In order to constrain the Nd sources in the North Pacific, we measured ɛNd on seawater from 5 stations across the North Pacific sampled by the INOPEX Cruise (2009). Below ~ 2000m, measured ɛNd values in the North Pacific match previously published data and correspond with NPDW values. Easternmost Sta. 32 (45.5°N 158.5°W) shows higher ɛNd (~ -3) than corresponding potential density (ρ) layers of other stations. This may indicate addition of a high-ɛNd source from Aleutians-Kamchatka volcanic margin along the transport path of Lower Circumpolar Deep Water (LCDW) from westernmost Sta. 44 (39.8°N 152.4°E) to Sta. 32. As a result, NPDW at Sta. 32, formed from the LCDW, also shows higher ɛNd than the other stations. Above ~ 2000m, samples at Sta. 5 (52.7°N 164.9°E) near the Aleutian-Kamchatka intersection have higher ɛNd than corresponding density layers of other stations, consistent with higher contributions from regional volcanoes. From the surface to ρ = 27.17 (250 - 750m, depending on location), a peak of ɛNd ~ -1.4 at ~ 100m (ρ = 26.56) at Sta. 5 coincides with a peak of dissolved 232Th, which indicates high lithogenic input from the Aleutian-Kamchatka margin (Hayes et al. 2014 EPSL). Thus the ɛNd peak likely reflects the remineralization of volcanic ash. ɛNd values of Sta. 32, 39 (38.0°N 164.5°E), 41 (38.4°N 160.3°E), and 44 generally increase with increasing density over this interval. Since the surface ɛNd at these stations (-4.8 to -4.0) indicates eolian dust input from the Asian deserts, an explanation for the increasing ɛNd is that the addition of a high-ɛNd volcanic source prevails over the remineralization of eolian desert dusts. Our results are consistent

  20. TRMM-observed summer warm rain over the tropical and subtropical Pacific Ocean: Characteristics and regional differences

    NASA Astrophysics Data System (ADS)

    Qin, Fang; Fu, Yunfei

    2016-06-01

    Based on the merged measurements from the TRMM Precipitation Radar and Visible and Infrared Scanner, refined characteristics (intensity, frequency, vertical structure, and diurnal variation) and regional differences of the warm rain over the tropical and subtropical Pacific Ocean (40ffiS-40ffiN, 120ffiE-70ffiW) in boreal summer are investigated for the period 1998-2012. The results reveal that three warm rain types (phased, pure, and mixed) exist over these regions. The phased warm rain, which occurs during the developing or declining stage of precipitation weather systems, is located over the central to western Intertropical Convergence Zone, South Pacific Convergence Zone, and Northwest Pacific. Its occurrence frequency peaks at midnight and minimizes during daytime with a 5.5-km maximum echo top. The frequency of this warm rain type is about 2.2%, and it contributes to 40% of the regional total rainfall. The pure warm rain is characterized by typical stable precipitation with an echo top lower than 4 km, and mostly occurs in Southeast Pacific. Although its frequency is less than 1.3%, this type of warm rain accounts for 95% of the regional total rainfall. Its occurrence peaks before dawn and it usually disappears in the afternoon. For the mixed warm rain, some may develop into deep convective precipitation, while most are similar to those of the pure type. The mixed warm rain is mainly located over the ocean east of Hawaii. Its frequency is 1.2%, but this type of warm rain could contribute to 80% of the regional total rainfall. The results also uncover that the mixed and pure types occur over the regions where SST ranges from 295 to 299 K, accompanied by relatively strong downdrafts at 500 hPa. Both the mixed and pure warm rains happen in a more unstable atmosphere, compared with the phased warm rain.

  1. Features of the short-term position variation of the west Pacific subtropical high during the torrential rain in Yangtze-Huaihe river valley and its possible cause

    NASA Astrophysics Data System (ADS)

    Guan, Zhaoyong; Yu, Bo; Wang, Lijuan; He, Jielin; Zeng, Gang

    2009-08-01

    By using the NCEP/NCAR daily reanalysis data, CMAP precipitation data , daily precipitation data of 740 stations in China and some remote sensing data, features of the short-term position variation of the west Pacific subtropical high(WPSH) during the torrential rain in Yangtze-Huaihe river valley and its possible cause are analyzed. Results show that the short-term position variation of WPSH is closely associated with the diabatic heating. During the torrential rain period, the apparent heating source and apparent moisture sink are exceptionally strong over Yangtze-Huaihe river valley( on the northwest side of WPSH )and the Bay of Bengal (to the west of WPSH). Based on the complete form of vertical vorticity tendency equation, it is found that the heating field over Yangtze-Huaihe river valley during the torrential rain period, which is in favor of the increase of cyclonic vorticity on the north side of WPSH, is unfavorable to the WPSH moving northward. And the heat source over the Bay of Bengal ,which is in favor of the increase of anti-cyclonic vorticity on the west of WPSH, may induce the westward extension of WPSH.

  2. Acoustic thermometry time series in the North Pacific

    NASA Astrophysics Data System (ADS)

    Dushaw, B. D.; Howe, B. M.; Mercer, J. A.; Worcester; Npal Group*, P. F.

    2002-12-01

    Acoustic measurements of large-scale, depth-averaged temperatures are continuing in the North Pacific as a follow on to the Acoustic Thermometry of Ocean Climate (ATOC) project. An acoustic source is located just north of Kauai. It transmits to six receivers to the east at 1-4-Mm ranges and one receiver to the northwest at about 4-Mm range. The transmission schedule is six times per day at four-day intervals. The time series were obtained from 1998 through 1999 and, after a two-year interruption because of permitting issues, began again in January 2002 to continue for at least another five years. The intense mesoscale thermal variability around Hawaii is evident in all time series; this variability is much greater than that observed near the California coast. The paths to the east, particularly those paths to the California coast, show cooling this year relative to the earlier data. The path to the northwest shows a modest warming. The acoustic rays sample depths below the mixed layer near Hawaii and to the surface as they near the California coast or extend north of the sub-arctic front. The temperatures measured acoustically are compared with those inferred from TOPEX altimetry, ARGO float data, and with ECCO (Estimating the Circulation and Climate of the Ocean) model output. This on-going data collection effort, to be augmented over the next years with a more complete observing array, can be used for, e.g., separating whole-basin climate change from low-mode spatial variability such as the Pacific Decadal Oscillation (PDO). [*NPAL (North Pacific Acoustic Laboratory) Group: J. A. Colosi, B. D. Cornuelle, B. D. Dushaw, M. A. Dzieciuch, B. M. Howe, J. A. Mercer, R. C. Spindel, and P. F. Worcester. Work supported by the Office of Naval Research.

  3. Reactive trace metals in the stratified central North Pacific

    SciTech Connect

    Bruland, K.W. ); Orians, K.J. ); Cowen, J.P. )

    1994-08-01

    Vertical concentration profiles of the dissolved and suspended particulate phases were determined for a suite of reactive trace metals, Al, Fe, Mn, Zn, and Cd, during summertime at a station in the center of the North Pacific gyre. During summer the euphotic zone becomes stratified, forming a shallow (0-25 m), oligotrophic, mixed layer overlying a subsurface (25-140 m), strongly-stratified region. The physical, biological, and chemical structure within the euphotic zone during this period enhanced the effect of atmospheric inputs of Al, Fe, and Mn on mixed layer concentrations. For example, the concentration of dissolved Fe in the surface mixed layer was eighteen times that observed at a depth of 100 m. The observed aeolian signature of these metals matched that predicted from estimates of atmospheric input during the period between the onset of stratification and sampling. The distributions of suspended particulate Al, Fe, and Mn all exhibited minima in the euphotic zone and increased with depth into the main thermocline. Particulate Al and Fe were then uniform with depth below 1000 m before increasing in the near bottom nepheloid layer. Average particulate phase concentrations in intermediate and deep waters of the central North Pacific were 1.0, 0.31, and 0.055 nmol[center dot]kg[sup [minus]1] for Al, Fe, and Mn, respectively. The distribution of particulate Cd exhibited a maximum within the subsurface euphotic zone. Particulate zinc also exhibited a surface maximum, albeit a smaller one. Concentrations of particulate Zn and Cd in intermediate and deep waters were 17 and 0.2 pmol[center dot]kg[sup [minus]1]. Substantial interbasin differences in particulate trace metals occur. Concentrations of suspended particulate Al, Fe, and Mn were three to four times lower in the central North Pacific than recently reported for the central North Atlantic gyre, consistent with differences in atmospheric input to these two regions.

  4. Gyre-scale Circulation and Coupling in the North Atlantic and North Pacific Oceans

    NASA Technical Reports Server (NTRS)

    Kelly, Kathryn A.

    1996-01-01

    I proposed to examine the annual cycle of intensity, latitudinal position and amount of meandering in the Gulf Stream, and compare the altimetric cycle with seasonal transport estimates from hydrographic data. We also proposed to examine large-scale fluctuations which alter the strength and location of the currents at gyre boundaries in the North Pacific.

  5. Two centuries of limited variability in subtropical North Atlantic thermocline ventilation.

    PubMed

    Goodkin, Nathalie F; Druffel, Ellen R M; Hughen, Konrad A; Doney, Scott C

    2012-01-01

    Ventilation and mixing of oceanic gyres is important to ocean-atmosphere heat and gas transfer, and to mid-latitude nutrient supply. The rates of mode water formation are believed to impact climate and carbon exchange between the surface and mid-depth water over decadal periods. Here, a record of (14)C/(12)C (1780-1940), which is a proxy for vertical ocean mixing, from an annually banded coral from Bermuda, shows limited inter-annual variability and a substantial Suess Effect (the decrease in (14)C/(12)C since 1900). The Sargasso Sea mixing rates between the surface and thermocline varied minimally over the past two centuries, despite changes to mean-hemispheric climate, including the Little Ice Age and variability in the North Atlantic Oscillation. This result indicates that regional formation rates of sub-tropical mode water are stable over decades, and that anthropogenic carbon absorbed by the ocean does not return to the surface at a variable rate. PMID:22549832

  6. Two centuries of limited variability in subtropical North Atlantic thermocline ventilation.

    PubMed

    Goodkin, Nathalie F; Druffel, Ellen R M; Hughen, Konrad A; Doney, Scott C

    2012-05-01

    Ventilation and mixing of oceanic gyres is important to ocean-atmosphere heat and gas transfer, and to mid-latitude nutrient supply. The rates of mode water formation are believed to impact climate and carbon exchange between the surface and mid-depth water over decadal periods. Here, a record of (14)C/(12)C (1780-1940), which is a proxy for vertical ocean mixing, from an annually banded coral from Bermuda, shows limited inter-annual variability and a substantial Suess Effect (the decrease in (14)C/(12)C since 1900). The Sargasso Sea mixing rates between the surface and thermocline varied minimally over the past two centuries, despite changes to mean-hemispheric climate, including the Little Ice Age and variability in the North Atlantic Oscillation. This result indicates that regional formation rates of sub-tropical mode water are stable over decades, and that anthropogenic carbon absorbed by the ocean does not return to the surface at a variable rate.

  7. Abundance and diversity of heterotrophic bacterial cells assimilating phosphate in the subtropical North Atlantic Ocean.

    PubMed

    Longnecker, Krista; Lomas, Michael W; Van Mooy, Benjamin A S

    2010-10-01

    Microorganisms play key roles in the cycles of carbon and nutrients in the ocean, and identifying the extent to which specific taxa contribute to these cycles will establish their ecological function. We examined the use of (33)P-phosphate to identify heterotrophic bacteria actively involved in the cycling of phosphate, an essential inorganic nutrient. Seawater from the sub-tropical North Atlantic Ocean was incubated with (33)P-phosphate and analysed by microautoradiography to determine the proportion and diversity of the bacterial community-assimilating phosphate. Complementary incubations using (3)H-leucine and (3)H-thymidine were also conducted. We found that a higher proportion of total heterotrophic bacterial cells in surface water samples assimilated phosphate compared with leucine or thymidine. Bacteria from all of the phylogenetic groups we identified by CARD-FISH were able to assimilate phosphate, although the abundances of cells within each group did not scale directly with the number found to assimilate phosphate. Furthermore, a significantly higher proportion of Alphaproteobacteria, Gammaproteobacteria and Cytophaga-like cells assimilated phosphate compared with leucine or thymidine. Our results suggest that a greater proportion of bacterial cells in surface waters are actively participating in the biogeochemical cycling of phosphorus, and possibly other elements, than is currently estimated through the use of (3)H-leucine or (3)H-thymidine.

  8. A composite study of the quasi-periodic subtropical wind maxima over the South Pacific during November 1984-April 1985

    NASA Technical Reports Server (NTRS)

    Ko, Ken-Chung; Vincent, Dayton G.

    1995-01-01

    A composite of 10 cases of zonal wind maxima at 200 hPa over the subtropical region stretching from Australia to the central Pacific is examined for the six-month period, November 1984-April 1985. This region is unique in that distinct westerly jets frequently form and propagate eastward at latitudes between 20 deg and 35 deg S in the summer season. Some statistical tests were applied and suggest that the flow patterns are quasi periodic, consisting of a tendency for new jet streaks to develop over the eastern Australian region approximately every one to two weeks. These jets then take about 10 days to propagate across the western Pacific before dissipating or, perhaps, moving toward higher latitudes. Their average propagation speed is approximately 4 m/s. An examination of the case-to-case variability of the jets provides additional evidence that they are significant features. A diagnosis of the trough/ridge systems at 200 and 850 hPa, together with calculations of the vertically integrated mean and shear kinetic energies suggests that baroclinic processes dominate in the entrance and center regions of the jet, whereas barotropic processes dominate in the exit and downstream regions.

  9. Bottom water warming in the North Pacific Ocean.

    PubMed

    Fukasawa, Masao; Freeland, Howard; Perkin, Ron; Watanabe, Tomowo; Uchida, Hiroshi; Nishina, Ayako

    2004-02-26

    Observations of changes in the properties of ocean waters have been restricted to surface or intermediate-depth waters, because the detection of change in bottom water is extremely difficult owing to the small magnitude of the expected signals. Nevertheless, temporal changes in the properties of such deep waters across an ocean basin are of particular interest, as they can be used to constrain the transport of water at the bottom of the ocean and to detect changes in the global thermohaline circulation. Here we present a comparison of a trans-Pacific survey completed in 1985 (refs 4, 5) and its repetition in 1999 (ref. 6). We find that the deepest waters of the North Pacific Ocean have warmed significantly across the entire width of the ocean basin. Our observations imply that changes in water properties are now detectable in water masses that have long been insulated from heat exchange with the atmosphere.

  10. Bottom water warming in the North Pacific Ocean.

    PubMed

    Fukasawa, Masao; Freeland, Howard; Perkin, Ron; Watanabe, Tomowo; Uchida, Hiroshi; Nishina, Ayako

    2004-02-26

    Observations of changes in the properties of ocean waters have been restricted to surface or intermediate-depth waters, because the detection of change in bottom water is extremely difficult owing to the small magnitude of the expected signals. Nevertheless, temporal changes in the properties of such deep waters across an ocean basin are of particular interest, as they can be used to constrain the transport of water at the bottom of the ocean and to detect changes in the global thermohaline circulation. Here we present a comparison of a trans-Pacific survey completed in 1985 (refs 4, 5) and its repetition in 1999 (ref. 6). We find that the deepest waters of the North Pacific Ocean have warmed significantly across the entire width of the ocean basin. Our observations imply that changes in water properties are now detectable in water masses that have long been insulated from heat exchange with the atmosphere. PMID:14985757

  11. Oligocene biogeography of the North Pacific (Implications of Mollusks)

    NASA Astrophysics Data System (ADS)

    Gladenkov, Yu. B.; Sinel'Nikova, V. N.

    2009-02-01

    First biogeographic maps are proposed for the late Eocene-Oligocene of the North Pacific. The maps are compiled based on distribution of 120 molluscan species studied in 30 reference sections of the region. The analyzed Machigar (Sakhalin), Rategin, Amanina-Gakh (western Kamchatka), Asagai-Momidziyama (Japan) type assemblages and their age analogues are well known and described long ago. Over 50 schematic biogeographic maps illustrate distribution areas of different taxa in the late Eocene, early Oligocene, and late Oligocene epochs. Some of them characterize distribution areas of individual species, while the others depict habitat areas of typical (Machigar and Rategin) assemblages or certain genera different in terms of their thermotropism. Analysis of the maps resulted in recognition of the Japan-Kamchatka and Kamchatka-North American paleoprovinces, and indications of general gradual seawater temperature decrease during the Oligocene are defined. The attention is paid to the commenced diversification of North Pacific biota that leads to formation of boreal communities and also to different-rank the amphipacific dusjunctions.

  12. Arctic-North Pacific coupled impacts on the late autumn cold in North America

    NASA Astrophysics Data System (ADS)

    Sung, Mi-Kyung; Kim, Baek-Min; Baek, Eun-Hyuk; Lim, Young-Kwon; Kim, Seong-Joong

    2016-08-01

    The Pacific decadal oscillation (PDO) is known to bring an anomalously cold (warm) period to southeastern (northwestern) North America during the cold season of its positive phase through a Rossby wave linkage. This study provides evidence that the remote connection between the North Pacific and the downstream temperature over central North America is strengthened by the warm arctic conditions over the Chukchi and East Siberian Sea, especially in the late autumn season. The modulation effect of the Arctic manifests itself as an altered Rossby wave response to a transient vorticity forcing that results from an equatorward storm track shift, which is induced collaboratively by the PDO and the warm Arctic. This observational finding is supported by two independent modeling experiments: (1) an idealized coupled GCM experiment being nudged toward the warm arctic surface condition and (2) a simple stationary wave model experiment forced by transient eddy forcing.

  13. Pacific Interdecadal Climate Variability: Linkages between the Tropics and the North Pacific during Boreal Winter since 1900.

    NASA Astrophysics Data System (ADS)

    Deser, Clara; Phillips, Adam S.; Hurrell, James W.

    2004-08-01

    This study examines the tropical linkages to interdecadal climate fluctuations over the North Pacific during boreal winter through a comprehensive and physically based analysis of a wide variety of observational datasets spanning the twentieth century. Simple difference maps between epochs of high sea level pressure over the North Pacific (1900 24 and 1947 76) and epochs of low pressure (1925 46 and 1977 97) are presented for numerous climate variables throughout the tropical Indo-Pacific region, including rainfall, cloudiness, sea surface temperature (SST), and sea level pressure. The results support the notion that the Tropics play a key role in North Pacific interdecadal climate variability. In particular, SST anomalies in the tropical Indian Ocean and southeast Pacific Ocean, rainfall and cloudiness anomalies in the vicinity of the South Pacific convergence zone, stratus clouds in the eastern tropical Pacific, and sea level pressure differences between the tropical southeast Pacific and Indian Oceans all exhibit prominent interdecadal fluctuations that are coherent with those in sea level pressure over the North Pacific. The spatial patterns of the interdecadal tropical climate anomalies are compared with those associated with ENSO, a predominantly interannual phenomenon; in general, the two are similar with some differences in relative spatial emphasis. Finally, a published 194-yr coral record in the western tropical Indian Ocean is shown to compare favorably with the twentieth-century instrumental records, indicating the potential for extending knowledge of tropical interdecadal climate variability to earlier time periods.


  14. 50 CFR 226.215 - Critical habitat for the North Pacific Right Whale (Eubalaena japonica).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 9 2011-10-01 2011-10-01 false Critical habitat for the North Pacific... DESIGNATED CRITICAL HABITAT § 226.215 Critical habitat for the North Pacific Right Whale (Eubalaena japonica... 56° 45′ N/153° 00′ W 57° 03′ N/153° 00′ W. (d) Maps of critical habitat for the North Pacific...

  15. 50 CFR 226.215 - Critical habitat for the North Pacific Right Whale (Eubalaena japonica).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 7 2010-10-01 2010-10-01 false Critical habitat for the North Pacific... DESIGNATED CRITICAL HABITAT § 226.215 Critical habitat for the North Pacific Right Whale (Eubalaena japonica... 56° 45′ N/153° 00′ W 57° 03′ N/153° 00′ W. (d) Maps of critical habitat for the North Pacific...

  16. 50 CFR 226.215 - Critical habitat for the North Pacific Right Whale (Eubalaena japonica).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 10 2012-10-01 2012-10-01 false Critical habitat for the North Pacific... DESIGNATED CRITICAL HABITAT § 226.215 Critical habitat for the North Pacific Right Whale (Eubalaena japonica... 56° 45′ N/153° 00′ W 57° 03′ N/153° 00′ W. (d) Maps of critical habitat for the North Pacific...

  17. Semidirect Dynamical and Radiative Impact of North African Dust Transport on Lower Tropospheric Clouds over the Subtropical North Atlantic in CESM 1.0

    SciTech Connect

    DeFlorio, Mike; Ghan, Steven J.; Singh, Balwinder; Miller, Arthur J.; Cayan, Dan; Russell, Lynn M.; Somerville, Richard C.

    2014-07-16

    This study uses a century length pre-industrial climate simulation by the Community Earth System Model (CESM 1.0) to explore statistical relationships between dust, clouds and atmospheric circulation, and to suggest a dynamical, rather than microphysical, mechanism linking subtropical North Atlantic lower tropospheric cloud cover with North African dust transport. The length of the run allows us to account for interannual variability of dust emissions and transport downstream of North Africa in the model. CESM’s mean climatology and probability distribution of aerosol optical depth in this region agrees well with available AERONET observations. In addition, CESM shows strong seasonal cycles of dust burden and lower tropospheric cloud fraction, with maximum values occurring during boreal summer, when a strong correlation between these two variables exists downstream of North Africa over the subtropical North Atlantic. Calculations of Estimated Inversion Strength (EIS) and composites of EIS on high and low downstream North Africa dust months during boreal summer reveal that dust is likely increasing inversion strength over this region due to both solar absorption and reflection. We find no evidence for a microphysical link between dust and lower tropospheric clouds in this region. These results yield new insight over an extensive period of time into the complex relationship between North African dust and lower tropospheric clouds over the open ocean, which has previously been hindered by spatiotemporal constraints of observations. Our findings lay a framework for future analyses using sub-monthly data over regions with different underlying dynamics.

  18. Impacts of decaying eastern and central Pacific El Niños on tropical cyclone activities over the western North Pacific in summer

    NASA Astrophysics Data System (ADS)

    Yang, Yuxing; Xie, Ruihuang; Wang, Faming; Huang, Fei

    2016-04-01

    We investigate the influences of the decaying eastern Pacific El Niño (EP - El Niño) and central Pacific El Niño (CP - El Niño) on tropical cyclone (TC) activities in the western North Pacific (WNP) during July, August and September (JAS). During this period, TC geneses and tracks are reduced in the central and eastern WNP. However, TC tracks reaching the Philippines increase, and more TC geneses appear west of 145°E during EP - El Niño. During CP - El Niño, tracks reaching the South China Sea (SCS) and southeast coast of China increase, and positive anomalies of TC genesis are found in the southern part of the central WNP and southern SCS. It is possible that the different variation of the anomalous anticyclone over east of the Philippines in the WNP induced by El Niños are instrumental to different TC variations in the two types of decaying El Niños during JAS. Compared with EP - El Niño, strengthening and northward expansion of the anomalous anticyclone during CP - El Niño cause a westward shift of the western Pacific subtropical high in summer, which is responsible for more westward TC tracks over the SCS and southeast coast of China. This northward expansion can cause the center of suppressed TC geneses in the central WNP to migrate further north during CP - El Niño. A decreased magnitude of vertical shear dominates the southern part of the central WNP and southern SCS, which enhances TC formation in these regions during CP - El Niño.

  19. Impacts of decaying eastern and central Pacific El Niños on tropical cyclone activities over the western North Pacific in summer

    NASA Astrophysics Data System (ADS)

    Yang, Yuxing; Xie, Ruihuang; Wang, Faming; Huang, Fei

    2016-07-01

    We investigate the influences of the decaying eastern Pacific El Niño (EP-El Niño) and central Pacific El Niño (CP-El Niño) on tropical cyclone (TC) activities in the western North Pacific (WNP) during July, August, and September (JAS). During this period, TC geneses and tracks are reduced in the central and eastern WNP. However, TC tracks reaching the Philippines increase, and more TC geneses appear west of 145°E during EP-El Niño. During CP-El Niño, tracks reaching the South China Sea (SCS) and southeast coast of China increase, and positive anomalies of TC genesis are found in the southern part of the central WNP and southern SCS. It is possible that the different variations of the anomalous anticyclone over east of the Philippines in the WNP induced by El Niños are instrumental to the different TC variations in the two types of decaying El Niños during JAS. Compared with EP-El Niño, strengthening and northward expansion of the anomalous anticyclone during CP-El Niño cause a westward shift of the western Pacific subtropical high in summer, which is responsible for more westward TC tracks over the SCS and southeast coast of China. This northward expansion can cause the center of suppressed TC geneses in the central WNP to migrate further north during CP-El Niño. A decreased magnitude of vertical shear dominates the southern part of the central WNP and southern SCS, which enhances TC formation in these regions during CP-El Niño.

  20. Offshore spawning of Conger myriaster in the western North Pacific: evidence for convergent migration strategies of anguilliform eels in the Atlantic and Pacific.

    PubMed

    Miller, Michael J; Yoshinaga, Tatsuki; Aoyama, Jun; Otake, Tsuguo; Mochioka, Noritaka; Kurogi, Hiroaki; Tsukamoto, Katsumi

    2011-06-01

    The spawning area of the common Japanese conger, Conger myriaster, had remained unknown because spawning adults or its newly hatched larvae were never collected. Using genetic identification, we determined that C. myriaster spawns far offshore in the western North Pacific, just west of the spawning area of the Japanese eel, Anguilla japonica. In June 2008, six newly hatched C. myriaster larvae, 5.6-6.9 mm, were collected at the eastern edge of where many small unidentified Conger leptocephali (7-20 mm) were collected previously. The offshore spawning location of C. myriaster is analogous to that of the American conger eel, Conger oceanicus, and the American eel, Anguilla rostrata, in the Sargasso Sea, suggesting that convergent evolution of large-scale reproductive migration strategies in both anguillid and conger eels has occurred in the north Atlantic and Pacific subtropical gyres. The realization that two anguillids, A. rostrata and A. japonica, and two congers, C. oceanicus and C. myriaster, have evolved almost identical migration strategies in widely separated ocean basins suggests that natural selection for larval survival and recruitment success has resulted in long offshore spawning migrations in two phylogenetically distant taxa of anguilliform eels. PMID:21509576

  1. Offshore spawning of Conger myriaster in the western North Pacific: evidence for convergent migration strategies of anguilliform eels in the Atlantic and Pacific

    NASA Astrophysics Data System (ADS)

    Miller, Michael J.; Yoshinaga, Tatsuki; Aoyama, Jun; Otake, Tsuguo; Mochioka, Noritaka; Kurogi, Hiroaki; Tsukamoto, Katsumi

    2011-06-01

    The spawning area of the common Japanese conger, Conger myriaster, had remained unknown because spawning adults or its newly hatched larvae were never collected. Using genetic identification, we determined that C. myriaster spawns far offshore in the western North Pacific, just west of the spawning area of the Japanese eel, Anguilla japonica. In June 2008, six newly hatched C. myriaster larvae, 5.6-6.9 mm, were collected at the eastern edge of where many small unidentified Conger leptocephali (7-20 mm) were collected previously. The offshore spawning location of C. myriaster is analogous to that of the American conger eel, Conger oceanicus, and the American eel, Anguilla rostrata, in the Sargasso Sea, suggesting that convergent evolution of large-scale reproductive migration strategies in both anguillid and conger eels has occurred in the north Atlantic and Pacific subtropical gyres. The realization that two anguillids, A. rostrata and A. japonica, and two congers, C. oceanicus and C. myriaster, have evolved almost identical migration strategies in widely separated ocean basins suggests that natural selection for larval survival and recruitment success has resulted in long offshore spawning migrations in two phylogenetically distant taxa of anguilliform eels.

  2. Geographic variation in Pacific herring growth in response to regime shifts in the North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Ito, Shin-ichi; Rose, Kenneth A.; Megrey, Bernard A.; Schweigert, Jake; Hay, Douglas; Werner, Francisco E.; Aita, Maki Noguchi

    2015-11-01

    Pacific herring populations at eight North Pacific Rim locations were simulated to compare basin-wide geographic variations in age-specific growth due to environmental influences on marine productivity and population-specific responses to regime shifts. Temperature and zooplankton abundance from a three-dimensional lower-trophic ecosystem model (NEMURO: North Pacific Ecosystem Model for Understanding Regional Oceanography) simulation from 1948 to 2002 were used as inputs to a herring bioenergetics growth model. Herring populations from California, the west coast of Vancouver Island (WCVI), Prince William Sound (PWS), Togiak Alaska, the western Bering Sea (WBS), the Sea of Okhotsk (SO), Sakhalin, and Peter the Great Bay (PGB) were examined. The half-saturation coefficients of herring feeding were calibrated to climatological conditions at each of the eight locations to reproduce averaged size-at-age data. The depth of averaging used for water temperature and zooplankton, and the maximum consumption rate parameter, were made specific to each location. Using the calibrated half-saturation coefficients, the 1948-2002 period was then simulated using daily values of water temperature and zooplankton densities interpolated from monthly model output. To detect regime shifts in simulated temperatures, zooplankton and herring growth rates, we applied sequential t-test analyses on the 54 years of hindcast simulation values. The detected shifts of herring age-5 growth showed closest match (69%) to the regime shift years (1957/58, 1970/71, 1976/77, 1988/89, 1998/99). We explored relationships among locations using cluster and principal component analyses. The first principal component of water temperature showed good correspondence to the Pacific Decadal Oscillation and all zooplankton groups showed a pan-Pacific decrease after the 1976/77 regime shift. However, the first principal component of herring growth rate showed decreased growth at the SO, PWS, WCVI and California

  3. Denali Ice Core Record of North Pacific Sea Surface Temperatures and the Pacific Decadal Oscillation

    NASA Astrophysics Data System (ADS)

    Polashenski, D.; Osterberg, E. C.; Winski, D.; Ferris, D. G.; Kreutz, K. J.; Wake, C. P.; Introne, D.

    2015-12-01

    Ice cores collected from high elevation alpine glaciers in the Alaska Range provide a unique opportunity to investigate changes in the regional climate of southern Alaska and the north Pacific over the past millennium. In this study, we seek to investigate changes in sea surface temperature (SST) in the north-central Pacific Ocean using the deuterium excess (d-excess) record from the Mt. Hunter ice cores collected in Denali National Park, Alaska. A collaborative research team from Dartmouth College and the Universities of Maine and New Hampshire collected two parallel ice cores to bedrock (208 m long) in May-June 2013 from the Mt. Hunter summit plateau (63º N, 151º W, 4,000 m above sea level). The cores were melted on a continuous melter system in the Dartmouth ice core lab and then analyzed for concentrations of major ions and trace elements, as well as stable water isotope ratios. The depth-age scale of the cores was determined using annual layer counting of δ18O and the concentrations of Mg, NH4, and Methanesulfonic acid (MSA) obtained by ion chromatography. The depth-age scale was validated using large, well-dated volcanic eruptions and the spike in 137Cs concentrations associated with nuclear weapons testing in 1963. Preliminary analyses indicate that the full record spans the past millennium. Analysis of the isotope data set extending back to 1938 using reanalysis data shows a positive correlation (p<0.05) between d-excess at the core site and the north-central Pacific SST. The north-central Pacific region of positive SST-d-excess correlation occurs at one node of the Pacific Decadal Oscillation (PDO), and thus the Denali cores are sensitive to PDO variability with low (high) d-excess associated with positive (negative) PDO index values. We also note a significant (p<0.05) declining trend in d-excess from 1938-2012, which we hypothesize to represent a rising proportion of Arctic moisture sources influencing Denali as Arctic temperatures and evaporation

  4. Paleonutrient and productivity records from the subarctic North Pacific for Pleistocene glacial terminations I to V

    NASA Astrophysics Data System (ADS)

    Gebhardt, Holger; Sarnthein, Michael; Grootes, Pieter M.; Kiefer, Thorsten; Kuehn, Hartmut; Schmieder, Frank; RöHl, Ursula

    2008-12-01

    Our study addresses fundamental questions of the mode and timing of orbital and millennial-scale changes in the meridional overturning circulation (MOC) of the subarctic North Pacific. Particular concerns are the vertical mixing, the present and past abundance of nutrients in surface waters despite strong stratification, and the North Pacific-North Atlantic seesaw of oscillations in sea surface temperature (SST). We do this by generating and interpreting multiple records for glacial terminations I-V down two long piston cores, one each from the western and eastern subarctic Pacific. Chlorins and biogenic opal are proxies for surface water productivity; δ13C of epibenthic foraminifera is a record of deepwater ventilation; and the δ13C of N. pachyderma sin. is a tracer of nutrients in subsurface waters that extend up to the sea surface during times of vertical mixing. The degree of mixing is traced by pairing SST and δ18O records of planktic surface and subsurface (pycnocline) dwellers. Tight age control is deduced from a suite of age-calibrated 14C plateau boundaries for Termination I and benthic δ18O and geomagnetic events for the last 800 ka. Carbon 14 paleoreservoir ages record the ages of surface and deep waters to uncover short-term changes in MOC over Termination I. We have defined a standard sequence of short-term productivity events for Termination I, also evident during terminations II to V and subsequent interglacials over the last 450 ka. The peak glacial regime of stable stratification and low productivity terminated, together with the end of ice rafting and melting, near 17 ka, ˜2000 years after the onset of Termination I. Pulses of vertical mixing and incursion of warm surface waters from the subtropics followed. Convected young water masses finally penetrated down to 3600-m water depth at 17.0 to less than 14.5 ka, significantly improving bottom water ventilation through the late deglacial and earliest interglacial. Mixing with upwelled nutrients

  5. North Pacific deglacial hypoxic events linked to abrupt ocean warming.

    PubMed

    Praetorius, S K; Mix, A C; Walczak, M H; Wolhowe, M D; Addison, J A; Prahl, F G

    2015-11-19

    Marine sediments from the North Pacific document two episodes of expansion and strengthening of the subsurface oxygen minimum zone (OMZ) accompanied by seafloor hypoxia during the last deglacial transition. The mechanisms driving this hypoxia remain under debate. We present a new high-resolution alkenone palaeotemperature reconstruction from the Gulf of Alaska that reveals two abrupt warming events of 4-5 degrees Celsius at the onset of the Bølling and Holocene intervals that coincide with sudden shifts to hypoxia at intermediate depths. The presence of diatomaceous laminations and hypoxia-tolerant benthic foraminiferal species, peaks in redox-sensitive trace metals, and enhanced (15)N/(14)N ratio of organic matter, collectively suggest association with high export production. A decrease in (18)O/(16)O values of benthic foraminifera accompanying the most severe deoxygenation event indicates subsurface warming of up to about 2 degrees Celsius. We infer that abrupt warming triggered expansion of the North Pacific OMZ through reduced oxygen solubility and increased marine productivity via physiological effects; following initiation of hypoxia, remobilization of iron from hypoxic sediments could have provided a positive feedback on ocean deoxygenation through increased nutrient utilization and carbon export. Such a biogeochemical amplification process implies high sensitivity of OMZ expansion to warming.

  6. The cycle of atmospheric cadmium over the North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Patterson, Thomas L.; Duce, Robert A.

    1991-02-01

    Bulk aerosol, cascade impactor, precipitation, and seawater samples were collected for a study of atmospheric cadmium at two sites in the Central North Pacific Ocean. The results of the analyses of these samples strongly suggest that the primary source of atmospheric Cd is the long-range transport of anthropogenic pollutant aerosol from Asia and Japan. The atmospheric concentration of Cd ranged from 1 to 60pg m-3 and was strongly correlated with the atmospheric Pb concentration. The deposition rate of atmospheric Cd was estimated to be between 6 and 70ng m-2 d-1 during the spring, and this flux is an insignificant source of Cd found in the surface waters of the Central North Pacific. The dissolubility of atmospheric Cd in seawater was determined. Virtually all of the Cd was released into an operationally defined dissolved state within 6h.

  7. North Pacific deglacial hypoxic events linked to abrupt ocean warming.

    PubMed

    Praetorius, S K; Mix, A C; Walczak, M H; Wolhowe, M D; Addison, J A; Prahl, F G

    2015-11-19

    Marine sediments from the North Pacific document two episodes of expansion and strengthening of the subsurface oxygen minimum zone (OMZ) accompanied by seafloor hypoxia during the last deglacial transition. The mechanisms driving this hypoxia remain under debate. We present a new high-resolution alkenone palaeotemperature reconstruction from the Gulf of Alaska that reveals two abrupt warming events of 4-5 degrees Celsius at the onset of the Bølling and Holocene intervals that coincide with sudden shifts to hypoxia at intermediate depths. The presence of diatomaceous laminations and hypoxia-tolerant benthic foraminiferal species, peaks in redox-sensitive trace metals, and enhanced (15)N/(14)N ratio of organic matter, collectively suggest association with high export production. A decrease in (18)O/(16)O values of benthic foraminifera accompanying the most severe deoxygenation event indicates subsurface warming of up to about 2 degrees Celsius. We infer that abrupt warming triggered expansion of the North Pacific OMZ through reduced oxygen solubility and increased marine productivity via physiological effects; following initiation of hypoxia, remobilization of iron from hypoxic sediments could have provided a positive feedback on ocean deoxygenation through increased nutrient utilization and carbon export. Such a biogeochemical amplification process implies high sensitivity of OMZ expansion to warming. PMID:26581293

  8. Apparent increase in coccolithophore abundance in the subtropical North Atlantic from 1990 to 2014

    NASA Astrophysics Data System (ADS)

    Krumhardt, Kristen M.; Lovenduski, Nicole S.; Freeman, Natalie M.; Bates, Nicholas R.

    2016-02-01

    As environmental conditions evolve with rapidly increasing atmospheric CO2, biological communities will change as species reorient their distributions, adapt, or alter their abundance. In the surface ocean, dissolved inorganic carbon (DIC) has been increasing over the past several decades as anthropogenic CO2 dissolves into seawater, causing acidification (decreases in pH and carbonate ion concentration). Calcifying phytoplankton, such as coccolithophores, are thought to be especially vulnerable to ocean acidification. How coccolithophores will respond to increasing carbon input has been a subject of much speculation and inspired numerous laboratory and mesocosm experiments, but how they are currently responding in situ is less well documented. In this study, we use coccolithophore (haptophyte) pigment data collected at the Bermuda Atlantic Time-series Study (BATS) site together with satellite estimates (1998-2014) of surface chlorophyll and particulate inorganic carbon (PIC) as a proxy for coccolithophore abundance to show that coccolithophore populations in the North Atlantic subtropical gyre have been increasing significantly over the past 2 decades. Over 1990-2012, we observe a 37 % increase in euphotic zone-integrated coccolithophore pigment abundance at BATS, though we note that this is sensitive to the period being analyzed. We further demonstrate that variability in coccolithophore chlorophyll a here is positively correlated with variability in nitrate and DIC (and especially the bicarbonate ion) in the upper 30 m of the water column. Previous studies have suggested that coccolithophore photosynthesis may benefit from increasing CO2, but calcification may eventually be hindered by low pHT (< 7.7). Given that DIC has been increasing at BATS by ˜ 1.4 µmol kg-1 yr-1 over the period of 1991-2012, we speculate that coccolithophore photosynthesis and perhaps calcification may have increased in response to anthropogenic CO2 input.

  9. A review of interaction between neon flying squid ( Ommastrephes bartramii) and oceanographic variability in the North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Yu, Wei; Chen, Xinjun; Yi, Qian; Tian, Siquan

    2015-08-01

    The neon flying squid ( Ommastrephes bartramii) is a short-lived opportunistic species widely distributed in subtropical and temperate waters in the North Pacific Ocean. The life cycle of O. bartramii from planktonic eggs to nektonic adults is closely linked to oceanographic conditions. The fluctuations in O. bartramii abundance and distribution tend to increase and widen continuously due to the heavy influences of ocean-climate events on various spatio-temporal scales. In this study, we reviewed the interaction between O. bartramii and oceanography variability in the North Pacific with respect to large-scale climatic-oceanic phenomena including El Niño, La Niña, Kuroshio, Oyashio and Pacific Decadal Oscillation (PDO), as well as regional environmental variables such as sea surface temperature (SST), sea surface height (SSH), sea surface salinity (SSS), chlorophyll-a (Chl- a) concentration, and plankton density. The population dynamics of O. bartramii is mediated mainly by meso- and large-scale climatic-oceanic events ( e.g., Kuroshio and Oyashio Currents) rather than other local environmental conditions ( e.g., SST and Chl- a concentration), because all of the oceanographic influences are imposed on the context of large-scale climate changes ( e.g., PDO). An unstructured-grid finite-volume coastal ocean model coupled with an individual-based model is proposed to simulate relevant physical-biological oceanographic processes for identifying ocean-climate influence and predicting O. bartramii distribution and abundance in the North Pacific. Future research needs to be focused on improving the knowledge about early life history of O. bartramii and evaluating the relationship between marine physical environment and two separate passive drifting life stages of O. bartramii including free-floating eggs and planktonic paralarvae.

  10. North Pacific Intermediate Water circulation enhanced by the closure of the Bering Strait

    NASA Astrophysics Data System (ADS)

    Knudson, Karla P.; Ravelo, Ana Christina

    2015-10-01

    The Bering Strait provides a shallow connection that allows freshwater to flow from the North Pacific into the North Atlantic, but this passage was closed during past glacials when sea level was at least 50 m lower than at present. Climate models investigating Bering Strait closure predict that this mechanism increases the salinity in the North Atlantic and reduces the salinity in the North Pacific, inducing a Pacific-Atlantic seesaw in meridional overturning circulation and poleward heat flux. However, the Pacific circulation response to Bering Strait closure, and thus the seesaw theory, has not been tested by long paleoceanographic records. We present long records of foraminiferal δ18O and δ13C from Integrated Ocean Drilling Program Site U1342 in the Bering Sea, which provide the first evidence of enhanced North Pacific Intermediate Water when the Bering Strait was closed during each of the extreme glacials of the last 1.2 Myr. These results suggest that orbital-scale variations in North Pacific Intermediate Water are coherent and in phase with variations in upper North Atlantic Deep Water but are unrelated to changes in lower North Atlantic Deep Water. Together, these results provide evidence for systematic, orbital-scale variability in North Pacific Ocean circulation and may challenge the idea of an orbital-scale Pacific-Atlantic seesaw.

  11. Environmental Forcing of Nitrogen Fixation in the Eastern Tropical and Sub-Tropical North Atlantic Ocean

    PubMed Central

    Rijkenberg, Micha J. A.; Langlois, Rebecca J.; Mills, Matthew M.; Patey, Matthew D.; Hill, Polly G.; Nielsdóttir, Maria C.; Compton, Tanya J.; LaRoche, Julie; Achterberg, Eric P.

    2011-01-01

    During the winter of 2006 we measured nifH gene abundances, dinitrogen (N2) fixation rates and carbon fixation rates in the eastern tropical and sub-tropical North Atlantic Ocean. The dominant diazotrophic phylotypes were filamentous cyanobacteria, which may include Trichodesmium and Katagnymene, with up to 106 L−1 nifH gene copies, unicellular group A cyanobacteria with up to 105 L−1 nifH gene copies and gamma A proteobacteria with up to 104 L−1 nifH gene copies. N2 fixation rates were low and ranged between 0.032–1.28 nmol N L−1 d−1 with a mean of 0.30±0.29 nmol N L−1 d−1 (1σ, n = 65). CO2-fixation rates, representing primary production, appeared to be nitrogen limited as suggested by low dissolved inorganic nitrogen to phosphate ratios (DIN:DIP) of about 2±3.2 in surface waters. Nevertheless, N2 fixation rates contributed only 0.55±0.87% (range 0.03–5.24%) of the N required for primary production. Boosted regression trees analysis (BRT) showed that the distribution of the gamma A proteobacteria and filamentous cyanobacteria nifH genes was mainly predicted by the distribution of Prochlorococcus, Synechococcus, picoeukaryotes and heterotrophic bacteria. In addition, BRT indicated that multiple a-biotic environmental variables including nutrients DIN, dissolved organic nitrogen (DON) and DIP, trace metals like dissolved aluminum (DAl), as a proxy of dust inputs, dissolved iron (DFe) and Fe-binding ligands as well as oxygen and temperature influenced N2 fixation rates and the distribution of the dominant diazotrophic phylotypes. Our results suggest that lower predicted oxygen concentrations and higher temperatures due to climate warming may increase N2 fixation rates. However, the balance between a decreased supply of DIP and DFe from deep waters as a result of more pronounced stratification and an enhanced supply of these nutrients with a predicted increase in deposition of Saharan dust may ultimately determine the consequences of climate

  12. Environmental forcing of nitrogen fixation in the eastern tropical and sub-tropical North Atlantic Ocean.

    PubMed

    Rijkenberg, Micha J A; Langlois, Rebecca J; Mills, Matthew M; Patey, Matthew D; Hill, Polly G; Nielsdóttir, Maria C; Compton, Tanya J; Laroche, Julie; Achterberg, Eric P

    2011-01-01

    During the winter of 2006 we measured nifH gene abundances, dinitrogen (N(2)) fixation rates and carbon fixation rates in the eastern tropical and sub-tropical North Atlantic Ocean. The dominant diazotrophic phylotypes were filamentous cyanobacteria, which may include Trichodesmium and Katagnymene, with up to 10(6) L(-1)nifH gene copies, unicellular group A cyanobacteria with up to 10(5) L(-1)nifH gene copies and gamma A proteobacteria with up to 10(4) L(-1)nifH gene copies. N(2) fixation rates were low and ranged between 0.032-1.28 nmol N L(-1) d(-1) with a mean of 0.30 ± 0.29 nmol N L(-1) d(-1) (1σ, n = 65). CO(2)-fixation rates, representing primary production, appeared to be nitrogen limited as suggested by low dissolved inorganic nitrogen to phosphate ratios (DIN:DIP) of about 2 ± 3.2 in surface waters. Nevertheless, N(2) fixation rates contributed only 0.55 ± 0.87% (range 0.03-5.24%) of the N required for primary production. Boosted regression trees analysis (BRT) showed that the distribution of the gamma A proteobacteria and filamentous cyanobacteria nifH genes was mainly predicted by the distribution of Prochlorococcus, Synechococcus, picoeukaryotes and heterotrophic bacteria. In addition, BRT indicated that multiple a-biotic environmental variables including nutrients DIN, dissolved organic nitrogen (DON) and DIP, trace metals like dissolved aluminum (DAl), as a proxy of dust inputs, dissolved iron (DFe) and Fe-binding ligands as well as oxygen and temperature influenced N(2) fixation rates and the distribution of the dominant diazotrophic phylotypes. Our results suggest that lower predicted oxygen concentrations and higher temperatures due to climate warming may increase N(2) fixation rates. However, the balance between a decreased supply of DIP and DFe from deep waters as a result of more pronounced stratification and an enhanced supply of these nutrients with a predicted increase in deposition of Saharan dust may ultimately determine the

  13. Surface water mixing estimated from 228Ra and 226Ra in the northwestern North Pacific.

    PubMed

    Kawakami, Hajime; Kusakabe, Masashi

    2008-08-01

    We investigated the horizontal distributions of (228)Ra and (226)Ra in surface waters of the northwestern North Pacific Ocean and Okhotsk Sea. Ratios of (228)Ra/(226)Ra were relatively large in the Tsugaru Current (0.6-0.8) and Okhotsk Sea (0.4-0.5), and small in the Western Subarctic Gyre (<0.2) and the Oyashio (0.25-0.3). (228)Ra/(226)Ra ratios in western Subarctic Water (SAW) rose slightly upon mixing with Okhotsk Water (OKW), before becoming the Oyashio Water (OYW). Also, ratios in the OYW increased during mixing with Tsugaru Current Water (TCW). Estimating from (228)Ra/(226)Ra ratios and (226)Ra activities with a simple two-end members-mixing model, we assumed that approximately 23% of the OYW originated from the OKW and the coastal region off northern Honshu (Japan) was strongly influenced by the TCW. From a diagram of (228)Ra activities against salinity, we could roughly divide surface seawater in the study area into the five water masses, which were SAW, OYW, OKW, TCW, and Subtropical Water (STW).

  14. Methylmercury production below the mixed layer in the North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Blum, Joel D.; Popp, Brian N.; Drazen, Jeffrey C.; Anela Choy, C.; Johnson, Marcus W.

    2013-10-01

    Mercury enters marine food webs in the form of microbially generated monomethylmercury. Microbial methylation of inorganic mercury, generating monomethylmercury, is widespread in low-oxygen coastal sediments. The degree to which microbes also methylate mercury in the open ocean has remained uncertain, however. Here, we present measurements of the stable isotopic composition of mercury in nine species of marine fish that feed at different depths in the central North Pacific Subtropical Gyre. We document a systematic decline in δ202Hg, Δ199Hg and Δ201Hg values with the depth at which fish feed. We show that these mercury isotope trends can be explained only if monomethylmercury is produced below the surface mixed layer, including in the underlying oxygen minimum zone, that is, between 50 and more than 400m depth. Specifically, we estimate that about 20-40% of the monomethylmercury detected below the surface mixed layer originates from the surface and enters deeper waters either attached to sinking particles, or in zooplankton and micronekton that migrate to depth. We suggest that the remaining monomethylmercury found at depth is produced below the surface mixed layer by methylating microbes that live on sinking particles. We suggest that microbial production of monomethylmercury below the surface mixed later contributes significantly to anthropogenic mercury uptake into marine food webs.

  15. North Pacific Cloud Feedbacks Inferred from Synoptic-Scale Dynamic and Thermodynamic Relationships

    NASA Technical Reports Server (NTRS)

    Norris, Joel R.; Iacobellis, Sam F.

    2005-01-01

    This study analyzed daily satellite cloud observations and reanalysis dynamical parameters to determine how mid-tropospheric vertical velocity and advection over the sea surface temperature gradient control midlatitude North Pacific cloud properties. Optically thick clouds with high tops are generated by synoptic ascent, but two different cloud regimes occur under synoptic descent. When vertical motion is downward during summer, extensive stratocumulus cloudiness is associated with near surface northerly wind, while frequent cloudless pixels occur with southerly wind. Examinations of ship-reported cloud types indicates that midlatitude stratocumulus breaks up as the the boundary level decouples when it is advected equatorward over warmer water. Cumulus is prevalent under conditions of synoptic descent and cold advection during winter. Poleward advection of subtropical air over colder water causes stratification of the near-surface layer that inhibits upward mixing of moisture and suppresses cloudiness until a fog eventually forms. Averaging of cloud and radiation data into intervals of 500-hPa vertical velocity and advection over the SST gradient enables the cloud response to changes in temperature and the stratification of the lower troposphere to be investigated independent of the dynamics.

  16. [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. PMID:17205791

  17. [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.

  18. Pigmented nanoflagellates grazing on Synechococcus: seasonal variations and effect of flagellate size in the coastal ecosystem of subtropical Western Pacific.

    PubMed

    Chan, Ya-Fan; Tsai, An-Yi; Chiang, Kuo-Ping; Hsieh, Chih-Hao

    2009-10-01

    We investigated seasonal variation of grazing impact of the pigmented nanoflagellates (PNF) with different sizes upon Synechococcus in the subtropical western Pacific coastal waters using grazing experiments with fluorescently labeled Synechococcus (FLS). For total PNF, conspicuous seasonal variations of ingestion rates on Synechococcus were found, and a functional response was observed. To further investigate the impact of different size groups, we separated the PNF into four categories (<3, 3-5, 5-10, and >10 microm). Our results indicated that the smallest PNF (<3 microm PNF) did not ingest FLS and was considered autotrophic. PNF of 3-5 microm in size made up most of the PNF community; however, their ingestion on Synechococcus was too low (0.1-1.9 Syn PNF(-1) h(-1)) to support their growth, and they had to depend on other prey or photosynthesis to survive. The ingestion rate of the 3-5 microm group exhibited no significant seasonal variation; by contrast, the ingestion rates of 5-10 and >10 microm PNFs showed significant seasonal variation. During the warm season, 3-5 microm PNF were responsible for the grazing of 12% of Synechococcus production, 5-10 microm PNF for 48%, and >10 microm PNF for 2%. Taken together, our results demonstrate that the PNF of 3-10 microm consumed most Synechococcus during the warm season and exhibited a significant functional response to the increase in prey concentration. PMID:19655080

  19. Ducting and Boundary Layer Refractivity Bias Correction in GPS Radio Occultation Soundings with MODIS over the Subtropical Eastern Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Xie, F.; Ao, C. O.; Adhikari, L.; Yu, X.

    2015-12-01

    Over the subtropical eastern Pacific, a large stratus cloud deck is often trapped below a strong inversion layer resulting from the combination of strong free tropospheric subsidence and the cool sea surface temperature underneath. The stable inversion leads to a sharp moisture decrease and a large negative refractivity gradient that often causes ducting right above the cloudy boundary layer (CBL). The presence of duct results in systematically negative biases in the GPS radio occultation (RO) refractivity (i.e., N-bias) inside the CBL due to a non-unique retrieval problem. An independent physical constraint is required to extract a unique and bias-free RO refractivity observation. In the overcast scenario, the inversion base temperature corresponds well to the cloud-top-temperature (CTT) of the stratus, which can be precisely measured from MODIS (Moderate Resolution Imaging Spectroradiometer) longwave infrared window channel. In this presentation, the MODIS CTT measurements are used as an independent constraint to correct the systematic biases in the near co-incident RO refractivity soundings from COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate). The sensitivity analysis on the reconstruction technique and the comparison of the reconstructed (bias-free) RO profiles with the radiosonde and ECMWF reanalysis will be presented. The synergy of GPS RO and MODIS cloud measurements provides model-independent observation of CBL thermodynamic structures that are crucial for understanding the boundary layer and low cloud processes in global weather and climate model simulations.

  20. Track-pattern-based seasonal prediction model for intense tropical cyclone activities over the North Atlantic and the western North Pacific basins

    NASA Astrophysics Data System (ADS)

    Choi, W.; Ho, C. H.

    2015-12-01

    Intense tropical cyclones (TCs) accompanying heavy rainfall and destructive wind gusts sometimes cause incredible socio-economic damages in the regions near their landfall. This study aims to analyze intense TC activities in the North Atlantic (NA) and the western North Pacific (WNP) basins and develop their track propensity seasonal prediction model. Considering that the number of TCs in the NA basin is much smaller than that in the WNP basin, different intensity criteria are used; category 1 and above for NA and category 3 and above for WNP based on Saffir-Simpson hurricane wind scale. By using a fuzzy clustering method, intense TC tracks in the NA and the WNP basins are classified into two and three representative patterns, respectively. Each pattern shows empirical relationships with climate variabilities such as sea surface temperature distribution associated with El Niño/La Niña or Atlantic Meridional Mode, Pacific decadal oscillation, upper and low level zonal wind, and strength of subtropical high. The hybrid statistical-dynamical method has been used to develop the seasonal prediction model for each pattern based on statistical relationships between the intense TC activity and seasonal averaged key predictors. The model performance is statistically assessed by cross validation for the training period (1982-2013) and has been applied for the 2014 and 2015 prediction. This study suggests applicability of this model to real prediction work and provide bridgehead of attempt for intense TC prediction.

  1. Reconstruction of deglacial Antarctic Intermediate Water variations in the subtropical North Atlantic

    NASA Astrophysics Data System (ADS)

    Xie, R. C.; Marcantonio, F.; Schmidt, M. W.

    2012-12-01

    Understanding intermediate water circulation across the last deglaciation is critical in assessing the role of oceanic heat transport associated with Atlantic Meridional Overturning Circulation (AMOC) variability across abrupt climate events. Abrupt changes in the northward flow of Antarctic Intermediate Water (AAIW) associated with AMOC reduction during the Younger Dryas (YD) and Heinrich Event 1 (H1) have been hypothesized, suggesting a potential connection between the Southern Ocean and high-latitude North Atlantic climate change. However, controversy persists as to whether the northward flow of AAIW is stronger or weaker during these abrupt cold events. One school maintains that there is an increase in the northward penetration of AAIW associated with weaker AMOC during both the YD and H1 cold events (e.g., [1-2]). However, each of these previous studies analyzed sediment cores retrieved from depths deeper than the modern depth range of AAIW (500-1100 m in the tropical and subtropical North Atlantic). Another school comes to the opposite conclusion, namely that there is a weakening of AAIW at least during one of the deglacial events (e.g., [3-4]). Here, we reconstruct deglacial AAIW variations using authigenic Nd isotope ratios from sediment recovered from core VM12-107 (11.33°N, 66.63°W; 1079 m) in the Southern Caribbean Sea. VM12-107 lies at the boundary between modern AAIW and modern upper NADW and thus is ideal for investigating the shoaling/deepening of the competing water masses as well as the variations of AAIW across abrupt climate events during the last deglaciation. We measured authigenic Nd isotope compositions in three different fractions in core VM12-107: the Fe-Mn oxyhydroxide leachate of the bulk sediment, the uncleaned planktonic foraminifera (mixed species), and fish debris wherever possible. Preliminary authigenic Nd isotope results from the Fe-Mn leachate show little variability in the ɛNd values, ranging from -9.6 to -10.6, during the

  2. Effect of a Pacific sea surface temperature anomaly on the circulation over North America

    NASA Technical Reports Server (NTRS)

    Shukla, J.; Bangaru, B.

    1979-01-01

    During the fall and winter of 1976-1977, sea surface temperature (SST) in the north Pacific was characterized by abnormally cold temperatures in the central and western portions of the north Pacific with a warm pool located off the west coast of the U.S. It was suggested that the north Pacific SST anomalies were one of the multiple causes of the abnormally cold temperatures in eastern North America during the 1976-1977 winter. An attempt was made to test this hypothesis by conducting a numerical experiment with the GLAS general circulation model.

  3. Ultrasonic whistles of killer whales (Orcinus orca) recorded in the North Pacific (L).

    PubMed

    Filatova, Olga A; Ford, John K B; Matkin, Craig O; Barrett-Lennard, Lance G; Burdin, Alexander M; Hoyt, Erich

    2012-12-01

    Ultrasonic whistles were previously found in North Atlantic killer whales and were suggested to occur in eastern North Pacific killer whales based on the data from autonomous recorders. In this study ultrasonic whistles were found in the recordings from two encounters with the eastern North Pacific offshore ecotype killer whales and one encounter with the western North Pacific killer whales of unknown ecotype. All ultrasonic whistles were highly stereotyped and all but two had downsweep contours. These results demonstrate that specific sound categories can be shared by killer whales from different ocean basins.

  4. Chemical oceanography. Increasing anthropogenic nitrogen in the North Pacific Ocean.

    PubMed

    Kim, Il-Nam; Lee, Kitack; Gruber, Nicolas; Karl, David M; Bullister, John L; Yang, Simon; Kim, Tae-Wook

    2014-11-28

    The recent increase in anthropogenic emissions of reactive nitrogen from northeastern Asia and the subsequent enhanced deposition over the extensive regions of the North Pacific Ocean (NPO) have led to a detectable increase in the nitrate (N) concentration of the upper ocean. The rate of increase of excess N relative to phosphate (P) was found to be highest (~0.24 micromoles per kilogram per year) in the vicinity of the Asian source continent, with rates decreasing eastward across the NPO, consistent with the magnitude and distribution of atmospheric nitrogen deposition. This anthropogenically driven increase in the N content of the upper NPO may enhance primary production in this N-limited region, potentially leading to a long-term change of the NPO from being N-limited to P-limited.

  5. Chemical oceanography. Increasing anthropogenic nitrogen in the North Pacific Ocean.

    PubMed

    Kim, Il-Nam; Lee, Kitack; Gruber, Nicolas; Karl, David M; Bullister, John L; Yang, Simon; Kim, Tae-Wook

    2014-11-28

    The recent increase in anthropogenic emissions of reactive nitrogen from northeastern Asia and the subsequent enhanced deposition over the extensive regions of the North Pacific Ocean (NPO) have led to a detectable increase in the nitrate (N) concentration of the upper ocean. The rate of increase of excess N relative to phosphate (P) was found to be highest (~0.24 micromoles per kilogram per year) in the vicinity of the Asian source continent, with rates decreasing eastward across the NPO, consistent with the magnitude and distribution of atmospheric nitrogen deposition. This anthropogenically driven increase in the N content of the upper NPO may enhance primary production in this N-limited region, potentially leading to a long-term change of the NPO from being N-limited to P-limited. PMID:25430767

  6. Increasing anthropogenic nitrogen in the North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Kim, Il-Nam; Lee, Kitack; Gruber, Nicolas; Karl, David M.; Bullister, John L.; Yang, Simon; Kim, Tae-Wook

    2014-11-01

    The recent increase in anthropogenic emissions of reactive nitrogen from northeastern Asia and the subsequent enhanced deposition over the extensive regions of the North Pacific Ocean (NPO) have led to a detectable increase in the nitrate (N) concentration of the upper ocean. The rate of increase of excess N relative to phosphate (P) was found to be highest (∼0.24 micromoles per kilogram per year) in the vicinity of the Asian source continent, with rates decreasing eastward across the NPO, consistent with the magnitude and distribution of atmospheric nitrogen deposition. This anthropogenically driven increase in the N content of the upper NPO may enhance primary production in this N-limited region, potentially leading to a long-term change of the NPO from being N-limited to P-limited.

  7. The plastic-associated microorganisms of the North Pacific Gyre.

    PubMed

    Carson, Henry S; Nerheim, Magnus S; Carroll, Katherine A; Eriksen, Marcus

    2013-10-15

    Microorganisms likely mediate processes affecting the fate and impacts of marine plastic pollution, including degradation, chemical adsorption, and colonization or ingestion by macroorganisms. We investigated the relationship between plastic-associated microorganism communities and factors such as location, temperature, salinity, plankton abundance, plastic concentration, item size, surface roughness, and polymer type. Small plastic items from the surface of the North Pacific Gyre in 2011 were examined using scanning electron microscopy. Bacillus bacteria (mean 1664 ± 247 individuals mm(-2)) and pennate diatoms (1097 ± 154 mm(-2)) were most abundant, with coccoid bacteria, centric diatoms, dinoflagellates, coccolithophores, and radiolarians present. Bacterial abundance was patchy, but increased on foamed polystyrene. Diatom abundance increased on items with rough surfaces and at sites with high plastic concentrations. Morphotype richness increased slightly on larger fragments, and a biogeographic transition occurred between pennate diatom groups. Better characterizing this community will aid in understanding how it interacts with plastic pollution. PMID:23993070

  8. The aluminosilicate fraction of North Pacific manganese nodules

    USGS Publications Warehouse

    Bischoff, J.L.; Piper, D.Z.; Leong, K.

    1981-01-01

    Nine nodules collected from throughout the deep North Pacific were analyzed for their mineralogy and major-element composition before and after leaching with Chester-Hughes solution. Data indicate that the mineral phillipsite accounts for the major part (> 75%) of the aluminosilicate fraction of all nodules. It is suggested that formation of phillipsite takes place on growing nodule surfaces coupled with the oxidation of absorbed manganous ion. All the nodules could be described as ternary mixtures of amorphous iron fraction (Fe-Ti-P), manganese oxide fraction (Mn-Mg Cu-Ni), and phillipsite fraction (Al-Si-K-Na), these fractions accounting for 96% of the variability of the chemical composition. ?? 1981.

  9. The plastic-associated microorganisms of the North Pacific Gyre.

    PubMed

    Carson, Henry S; Nerheim, Magnus S; Carroll, Katherine A; Eriksen, Marcus

    2013-10-15

    Microorganisms likely mediate processes affecting the fate and impacts of marine plastic pollution, including degradation, chemical adsorption, and colonization or ingestion by macroorganisms. We investigated the relationship between plastic-associated microorganism communities and factors such as location, temperature, salinity, plankton abundance, plastic concentration, item size, surface roughness, and polymer type. Small plastic items from the surface of the North Pacific Gyre in 2011 were examined using scanning electron microscopy. Bacillus bacteria (mean 1664 ± 247 individuals mm(-2)) and pennate diatoms (1097 ± 154 mm(-2)) were most abundant, with coccoid bacteria, centric diatoms, dinoflagellates, coccolithophores, and radiolarians present. Bacterial abundance was patchy, but increased on foamed polystyrene. Diatom abundance increased on items with rough surfaces and at sites with high plastic concentrations. Morphotype richness increased slightly on larger fragments, and a biogeographic transition occurred between pennate diatom groups. Better characterizing this community will aid in understanding how it interacts with plastic pollution.

  10. Environmental Influences on the Intensity Changes of Tropical Cyclones over the Western North Pacific

    NASA Astrophysics Data System (ADS)

    Shu, Shoujuan; Zhang, Fuqing; Wang, Yuan

    2015-04-01

    The influence of environmental conditions on the intensity changes of tropical cyclones (TCs) over the western North Pacific (WNP) is investigated through examination of 37 TCs during 2000-2011 that interacted directly with the western North Pacific subtropical high (WNPSH). Comprehensive composite analysis of the environmental conditions is performed for two stages of storms: one is categorized as intensifying events (maximum wind speed increases by 15 kts over 48 h) and the other is categorized as weakening events (maximum wind speed decreases by 15 kts over 48 h). Comparison of the composite analysis of these two cases show that environmental conditions associated with the WNPSH play important roles in the intensity changes of TCs over the WNP. When a TC moves along the southern periphery of the WNPSH, the relatively weaker easterly environmental vertical wind shear helps bring warm moist air from the south and southeast to its southeast quadrant within 500 km , which is favourable for the TC to intensify. On the other hand, when a TC moves along the western edge of the WNPSH, under the combined influences of the WNPSH and an upper-level westerly trough, a strong westerly vertical shear promotes the intrusion of dry environmental air associated with the WNPSH from the north and northwest, which may lead to the inhibition of moisture supply and convection over the west half of the TC and thus its weakening. These composite results are consistent with those with additonal geographic restrictions, suggesting that the dry air intrusion and the vertical wind shear (VWS) associated with the WNPSH, indeed affect the intensity changes of TCs over the WNP beyond the difference related solely to variations in geographical locations. The average sea surface temperature (SST) of 27.6° for the weakening events is also lower than an average of 28.9° for the strengthening events, but remains above the critical value of 27° for TC intensification, suggesting that the SST may

  11. Environmental influences on the intensity changes of tropical cyclones over the western North Pacific

    NASA Astrophysics Data System (ADS)

    Shu, Shoujuan; Zhang, Fuqing; Ming, Jie; Wang, Yuan

    2014-06-01

    The influence of environmental conditions on the intensity changes of tropical cyclones (TCs) over the western North Pacific (WNP) is investigated through examination of 37 TCs during 2000-2011 that interacted directly with the western North Pacific subtropical high (WNPSH). Comprehensive composite analysis of the environmental conditions is performed for two stages of storms: one is categorized as intensifying events (maximum wind speed increases by 15 kn over 48 h) and the other is categorized as weakening events (maximum wind speed decreases by 15 kn over 48 h). Comparison of the composite analysis of these two cases show that environmental conditions associated with the WNPSH play important roles in the intensity changes of TCs over the WNP. When a TC moves along the southern periphery of the WNPSH, the relatively weaker easterly environmental vertical wind shear helps bring warm moist air from the south and southeast to its southeast quadrant within 500 km, which is favorable for the TC to intensify. However, when a TC moves along the western edge of the WNPSH, under the combined influences of the WNPSH and an upper-level westerly trough, a strong westerly vertical shear promotes the intrusion of dry environmental air associated with the WNPSH from the north and northwest, which may lead to the inhibition of moisture supply and convection over the western half of the TC and thus its weakening. These composite results are consistent with those with additional geographic restrictions, suggesting that the dry air intrusion and the vertical wind shear (VWS) associated with the WNPSH, indeed affect the intensity changes of TCs over the WNP beyond the difference related solely to variations in geographical locations. The average sea surface temperature (SST) of 27.6 °C for the weakening events is also lower than an average of 28.9 °C for the strengthening events, but remains above the critical value of 27 °C for TC intensification, suggesting that the SST may be

  12. Annual and longitudinal variations of the Pacific North Equatorial Countercurrent

    NASA Technical Reports Server (NTRS)

    Lolk, Nina K.

    1992-01-01

    The climatological annual cycle of the Pacific North Equatorial Countercurrent (NECC) simulated by an ocean general circulation model (OGCM) was studied. The longitudinal variation of transports, degree of geostrophy, and the relationship between Ekman pumping and vertical displacement of the thermocline were emphasized. The longitudinal variation was explored using six sections along 150 deg E, 180 deg, 160 deg W, 140 deg W, 125 deg W, and 110 deg W. A primitive equation OGCM of the Pacific Ocean was run for three years and the fields used were from the third year. The fields consisted of zonal, meridional, and vertical current components and temperature and salinity averaged every three days. The model was forced with the Hellerman and Rosenstein climatological wind stress. The mean annual eastward transport (19.9 Sv) was largest at 160 deg W. The maximum-current boundaries along 160 deg W were 9.2 deg N (1.0 deg), 5.1 deg N (1.1 deg), and 187 m (90.6 m). The annual-cycle amplitude of the NECC was greatest between 160 deg W and 140 deg W. Although the NECC is geostrophic to the first order, deviations from geostrophy were found in the boreal spring and summer near the southern boundary and near the surface. Meridional local acceleration played a role between 3 deg N-5 deg N.

  13. Phytoplankton across Tropical and Subtropical Regions of the Atlantic, Indian and Pacific Oceans.

    PubMed

    Estrada, Marta; Delgado, Maximino; Blasco, Dolors; Latasa, Mikel; Cabello, Ana María; Benítez-Barrios, Verónica; Fraile-Nuez, Eugenio; Mozetič, Patricija; Vidal, Montserrat

    2016-01-01

    We examine the large-scale distribution patterns of the nano- and microphytoplankton collected from 145 oceanic stations, at 3 m depth, the 20% light level and the depth of the subsurface chlorophyll maximum, during the Malaspina-2010 Expedition (December 2010-July 2011), which covered 15 biogeographical provinces across the Atlantic, Indian and Pacific oceans, between 35°N and 40°S. In general, the water column was stratified, the surface layers were nutrient-poor and the nano- and microplankton (hereafter phytoplankton, for simplicity, although it included also heterotrophic protists) community was dominated by dinoflagellates, other flagellates and coccolithophores, while the contribution of diatoms was only important in zones with shallow nutriclines such as the equatorial upwelling regions. We applied a principal component analysis to the correlation matrix among the abundances (after logarithmic transform) of the 76 most frequent taxa to synthesize the information contained in the phytoplankton data set. The main trends of variability identified consisted of: 1) A contrast between the community composition of the upper and the lower parts of the euphotic zone, expressed respectively by positive or negative scores of the first principal component, which was positively correlated with taxa such as the dinoflagellates Oxytoxum minutum and Scrippsiella spp., and the coccolithophores Discosphaera tubifera and Syracosphaera pulchra (HOL and HET), and negatively correlated with taxa like Ophiaster hydroideus (coccolithophore) and several diatoms, 2) a general abundance gradient between phytoplankton-rich regions with high abundances of dinoflagellate, coccolithophore and ciliate taxa, and phytoplankton-poor regions (second principal component), 3) differences in dominant phytoplankton and ciliate taxa among the Atlantic, the Indian and the Pacific oceans (third principal component) and 4) the occurrence of a diatom-dominated assemblage (the fourth principal

  14. Gross and microscopic pathology of lesions in Pocillopora spp. from the subtropical eastern Pacific.

    PubMed

    Rodríguez-Villalobos, Jenny Carolina; Rocha-Olivares, Axayácatl; Work, Thierry Martin; Calderon-Aguilera, Luis Eduardo; Cáceres-Martínez, Jorge Abelardo

    2014-07-01

    Coral reefs are threatened by a variety of factors including diseases that have caused significant damage in some regions such as in the Caribbean. At present, no data are available on coral diseases in the Mexican Pacific where Pocillopora spp. is a dominant component of coral communities. Here, we describe gross and microscopic morphology of lesions found in pocilloporids at four sites in the Mexican Pacific. Corals were identified and their lesions photographed and quantified in the field. Tissue samples were collected from healthy and affected colonies for histopathology. We recorded seven species of pocilloporids at the study sites with Isla Isabel being the location with the highest coral diversity (H'=1.27). Lesions were present in 42% of the colonies and included discoloration (32%), predation-induced tissue loss (30%), unexplained tissue loss (3%) and overgrowth by sponges or algae (35%). The most affected species, P. damicornis (50%), was also one of the most common in the region. No species was more prone to a particular lesion, but there was a significant association between location and the presence of lesions. Northern Islas Marietas (61%) and Isla Isabel (41%) had the highest prevalence of lesions, followed by Manzanillo (37%) and Bahías de Huatulco (23%). Histological changes included atrophy of the surface body wall with depletion of zooxanthellae (91%) in corals with discoloration (bleaching). Ablation of tissue from mesoglea (18%) was also observed. Colonies with unexplained tissue loss showed atrophy and thinning of the epidermis (89%), characterized by cuboidal instead of pseudocolumnar cells normally found in healthy pseudocolumnar ciliated epithelium. Bacterial aggregates between the mesoglea and gastrodermis (11%) were very conspicuous in healthy and diseased corals. Lesions produced by fish bites and gastropods were associated with tissue atrophy (40%) and, in some cases, algal overgrowth near the lesion (20%). No infectious agents

  15. Gross and microscopic pathology of lesions in Pocillopora spp. from the subtropical eastern Pacific.

    PubMed

    Rodríguez-Villalobos, Jenny Carolina; Rocha-Olivares, Axayácatl; Work, Thierry Martin; Calderon-Aguilera, Luis Eduardo; Cáceres-Martínez, Jorge Abelardo

    2014-07-01

    Coral reefs are threatened by a variety of factors including diseases that have caused significant damage in some regions such as in the Caribbean. At present, no data are available on coral diseases in the Mexican Pacific where Pocillopora spp. is a dominant component of coral communities. Here, we describe gross and microscopic morphology of lesions found in pocilloporids at four sites in the Mexican Pacific. Corals were identified and their lesions photographed and quantified in the field. Tissue samples were collected from healthy and affected colonies for histopathology. We recorded seven species of pocilloporids at the study sites with Isla Isabel being the location with the highest coral diversity (H'=1.27). Lesions were present in 42% of the colonies and included discoloration (32%), predation-induced tissue loss (30%), unexplained tissue loss (3%) and overgrowth by sponges or algae (35%). The most affected species, P. damicornis (50%), was also one of the most common in the region. No species was more prone to a particular lesion, but there was a significant association between location and the presence of lesions. Northern Islas Marietas (61%) and Isla Isabel (41%) had the highest prevalence of lesions, followed by Manzanillo (37%) and Bahías de Huatulco (23%). Histological changes included atrophy of the surface body wall with depletion of zooxanthellae (91%) in corals with discoloration (bleaching). Ablation of tissue from mesoglea (18%) was also observed. Colonies with unexplained tissue loss showed atrophy and thinning of the epidermis (89%), characterized by cuboidal instead of pseudocolumnar cells normally found in healthy pseudocolumnar ciliated epithelium. Bacterial aggregates between the mesoglea and gastrodermis (11%) were very conspicuous in healthy and diseased corals. Lesions produced by fish bites and gastropods were associated with tissue atrophy (40%) and, in some cases, algal overgrowth near the lesion (20%). No infectious agents

  16. Phytoplankton across Tropical and Subtropical Regions of the Atlantic, Indian and Pacific Oceans

    PubMed Central

    Estrada, Marta; Delgado, Maximino; Blasco, Dolors; Latasa, Mikel; Cabello, Ana María; Benítez-Barrios, Verónica; Fraile-Nuez, Eugenio; Mozetič, Patricija; Vidal, Montserrat

    2016-01-01

    We examine the large-scale distribution patterns of the nano- and microphytoplankton collected from 145 oceanic stations, at 3 m depth, the 20% light level and the depth of the subsurface chlorophyll maximum, during the Malaspina-2010 Expedition (December 2010-July 2011), which covered 15 biogeographical provinces across the Atlantic, Indian and Pacific oceans, between 35°N and 40°S. In general, the water column was stratified, the surface layers were nutrient-poor and the nano- and microplankton (hereafter phytoplankton, for simplicity, although it included also heterotrophic protists) community was dominated by dinoflagellates, other flagellates and coccolithophores, while the contribution of diatoms was only important in zones with shallow nutriclines such as the equatorial upwelling regions. We applied a principal component analysis to the correlation matrix among the abundances (after logarithmic transform) of the 76 most frequent taxa to synthesize the information contained in the phytoplankton data set. The main trends of variability identified consisted of: 1) A contrast between the community composition of the upper and the lower parts of the euphotic zone, expressed respectively by positive or negative scores of the first principal component, which was positively correlated with taxa such as the dinoflagellates Oxytoxum minutum and Scrippsiella spp., and the coccolithophores Discosphaera tubifera and Syracosphaera pulchra (HOL and HET), and negatively correlated with taxa like Ophiaster hydroideus (coccolithophore) and several diatoms, 2) a general abundance gradient between phytoplankton-rich regions with high abundances of dinoflagellate, coccolithophore and ciliate taxa, and phytoplankton-poor regions (second principal component), 3) differences in dominant phytoplankton and ciliate taxa among the Atlantic, the Indian and the Pacific oceans (third principal component) and 4) the occurrence of a diatom-dominated assemblage (the fourth principal

  17. Phytoplankton across Tropical and Subtropical Regions of the Atlantic, Indian and Pacific Oceans.

    PubMed

    Estrada, Marta; Delgado, Maximino; Blasco, Dolors; Latasa, Mikel; Cabello, Ana María; Benítez-Barrios, Verónica; Fraile-Nuez, Eugenio; Mozetič, Patricija; Vidal, Montserrat

    2016-01-01

    We examine the large-scale distribution patterns of the nano- and microphytoplankton collected from 145 oceanic stations, at 3 m depth, the 20% light level and the depth of the subsurface chlorophyll maximum, during the Malaspina-2010 Expedition (December 2010-July 2011), which covered 15 biogeographical provinces across the Atlantic, Indian and Pacific oceans, between 35°N and 40°S. In general, the water column was stratified, the surface layers were nutrient-poor and the nano- and microplankton (hereafter phytoplankton, for simplicity, although it included also heterotrophic protists) community was dominated by dinoflagellates, other flagellates and coccolithophores, while the contribution of diatoms was only important in zones with shallow nutriclines such as the equatorial upwelling regions. We applied a principal component analysis to the correlation matrix among the abundances (after logarithmic transform) of the 76 most frequent taxa to synthesize the information contained in the phytoplankton data set. The main trends of variability identified consisted of: 1) A contrast between the community composition of the upper and the lower parts of the euphotic zone, expressed respectively by positive or negative scores of the first principal component, which was positively correlated with taxa such as the dinoflagellates Oxytoxum minutum and Scrippsiella spp., and the coccolithophores Discosphaera tubifera and Syracosphaera pulchra (HOL and HET), and negatively correlated with taxa like Ophiaster hydroideus (coccolithophore) and several diatoms, 2) a general abundance gradient between phytoplankton-rich regions with high abundances of dinoflagellate, coccolithophore and ciliate taxa, and phytoplankton-poor regions (second principal component), 3) differences in dominant phytoplankton and ciliate taxa among the Atlantic, the Indian and the Pacific oceans (third principal component) and 4) the occurrence of a diatom-dominated assemblage (the fourth principal

  18. Gross and microscopic pathology of lesions in Pocillopora spp. from the subtropical eastern Pacific

    USGS Publications Warehouse

    Rodríguez-Villalobos, Jenny Carolina; Rocha-Olivares, Axayácatl; Work, Thierry Martin; Calderon-Aguilera, Luis Eduardo; Cáceres-Martínez, Jorge Abelardo

    2014-01-01

    Coral reefs are threatened by a variety of factors including diseases that have caused significant damage in some regions such as in the Caribbean. At present, no data are available on coral diseases in the Mexican Pacific where Pocillopora spp. is a dominant component of coral communities. Here, we describe gross and microscopic morphology of lesions found in pocilloporids at four sites in the Mexican Pacific. Corals were identified and their lesions photographed and quantified in the field. Tissue samples were collected from healthy and affected colonies for histopathology. We recorded seven species of pocilloporids at the study sites with Isla Isabel being the location with the highest coral diversity (H′ = 1.27). Lesions were present in 42% of the colonies and included discoloration (32%), predation-induced tissue loss (30%), unexplained tissue loss (3%) and overgrowth by sponges or algae (35%). The most affected species, P. damicornis (50%), was also one of the most common in the region. No species was more prone to a particular lesion, but there was a significant association between location and the presence of lesions. Northern Islas Marietas (61%) and Isla Isabel (41%) had the highest prevalence of lesions, followed by Manzanillo (37%) and Bahías de Huatulco (23%). Histological changes included atrophy of the surface body wall with depletion of zooxanthellae (91%) in corals with discoloration (bleaching). Ablation of tissue from mesoglea (18%) was also observed. Colonies with unexplained tissue loss showed atrophy and thinning of the epidermis (89%), characterized by cuboidal instead of pseudocolumnar cells normally found in healthy pseudocolumnar ciliated epithelium. Bacterial aggregates between the mesoglea and gastrodermis (11%) were very conspicuous in healthy and diseased corals. Lesions produced by fish bites and gastropods were associated with tissue atrophy (40%) and, in some cases, algal overgrowth near the lesion (20%). No infectious agents

  19. Reduction of systematic errors in regional climate simulations of the summer monsoon over East Asia and the western North Pacific by applying the spectral nudging technique

    NASA Astrophysics Data System (ADS)

    Cha, Dong-Hyun; Lee, Dong-Kyou

    2009-07-01

    In this study, the systematic errors in regional climate simulation of 28-year summer monsoon over East Asia and the western North Pacific (WNP) and the impact of the spectral nudging technique (SNT) on the reduction of the systematic errors are investigated. The experiment in which the SNT is not applied (the CLT run) has large systematic errors in seasonal mean climatology such as overestimated precipitation, weakened subtropical high, and enhanced low-level southwesterly over the subtropical WNP, while in the experiment using the SNT (the SP run) considerably smaller systematic errors are resulted. In the CTL run, the systematic error of simulated precipitation over the ocean increases significantly after mid-June, since the CTL run cannot reproduce the principal intraseasonal variation of summer monsoon precipitation. The SP run can appropriately capture the spatial distribution as well as temporal variation of the principal empirical orthogonal function mode, and therefore, the systematic error over the ocean does not increase after mid-June. The systematic error of simulated precipitation over the subtropical WNP in the CTL run results from the unreasonable positive feedback between precipitation and surface latent heat flux induced by the warm sea surface temperature anomaly. Since the SNT plays a role in decreasing the positive feedback by improving monsoon circulations, the SP run can considerably reduce the systematic errors of simulated precipitation as well as atmospheric fields over the subtropical WNP region.

  20. Similarity in microbial amino acid uptake in surface waters of the North and South Atlantic (sub-)tropical gyres

    NASA Astrophysics Data System (ADS)

    Hill, Polly G.; Mary, Isabelle; Purdie, Duncan A.; Zubkov, Mikhail V.

    2011-12-01

    The Earth’s most extensive biomes - the oceanic subtropical gyres - are considered to be expanding with current surface ocean warming. Although it is well established that microbial communities control gyre biogeochemistry, comparisons of their metabolic activities between gyres are limited. In order to estimate metabolic activities including production of microbial communities, the uptake rates of amino acids leucine, methionine and tyrosine at ambient concentrations were estimated in surface waters of the Atlantic Ocean using radioisotopically labelled tracers. Data were acquired during six research cruises covering main oceanic provinces herein termed: North and South Atlantic Gyres, Bermuda Atlantic Time-series Study site (BATS), Equatorial region, and Mauritanian Upwelling (off Cape Blanc). Data were divided between provinces, the extents of which were identified by ocean colour data, in order to achieve provincial mean uptake rates. Leucine and methionine uptake rates did not differ between sampling periods, and were comparable between the North and South subtropical gyres. Furthermore, variation in uptake rates measured throughout the two oligotrophic gyres, where sampling covered ∼4 × 10 6 km 2, was considerably lower than that measured within the Mauritanian Upwelling and Equatorial regions, and even at the BATS site. Tyrosine was generally the slowest of the amino acids to be taken up, however, it was assimilated faster than methionine within the Mauritanian Upwelling region. Thus, we propose that one value for leucine (12.6 ± 3.2 pmol L -1 h -1) and methionine (10.0 ± 3.3 pmol L -1 h -1) uptake could be applied to the oligotrophic subtropical gyres of the Atlantic Ocean. However, with the significantly lower uptake rates observed at the BATS site, we would not advise extrapolation to the Sargasso Sea.

  1. Origin and fluxes of nitrous oxide along a latitudinal transect in western North Pacific: Controls and regional significance

    NASA Astrophysics Data System (ADS)

    Breider, Florian; Yoshikawa, Chisato; Abe, Hitomi; Toyoda, Sakae; Yoshida, Naohiro

    2015-07-01

    Nitrous oxide (N2O) is an atmospheric trace gas playing an important role in both radiative forcing and stratospheric ozone depletion. The oceans are the second most important natural source of N2O. The magnitude of the flux of this source is poorly constrained. Moreover, the relative importance of the microbial processes leading to the formation or the consumption of N2O in oceans remains unclear. We present here fluxes and isotope and isotopomer signatures of N2O measured at three stations located along a latitudinal transect in subtropical and subarctic western North Pacific. These results indicate that about 30% to 55% of the oceanic flux of N2O to the atmosphere originates from the deep euphotic and shallow aphotic zones. The sea-to-air fluxes of N2O calculated using an isotope mass balance model indicate that the emission rate of N2O in subarctic waters is about 2 times higher than in oligotrophic subtropical waters suggesting that nutrient-rich water coming from the western subarctic gyre stimulates the N2O production. Moreover, isotopomer analysis has revealed that in shallow water N2O originates from nitrification and nitrifier denitrification processes, and its distribution in the water column is partly controlled by the incident solar radiation. The results of this study contribute to better constrain the global N2O budget and provide important information to better predict the future evolution of the oceanic emissions of N2O.

  2. Genomes and gene expression across light and productivity gradients in eastern subtropical Pacific microbial communities.

    PubMed

    Dupont, Chris L; McCrow, John P; Valas, Ruben; Moustafa, Ahmed; Walworth, Nathan; Goodenough, Ursula; Roth, Robyn; Hogle, Shane L; Bai, Jing; Johnson, Zackary I; Mann, Elizabeth; Palenik, Brian; Barbeau, Katherine A; Venter, J Craig; Allen, Andrew E

    2015-05-01

    Transitions in community genomic features and biogeochemical processes were examined in surface and subsurface chlorophyll maximum (SCM) microbial communities across a trophic gradient from mesotrophic waters near San Diego, California to the oligotrophic Pacific. Transect end points contrasted in thermocline depth, rates of nitrogen and CO2 uptake, new production and SCM light intensity. Relative to surface waters, bacterial SCM communities displayed greater genetic diversity and enrichment in putative sulfur oxidizers, multiple actinomycetes, low-light-adapted Prochlorococcus and cell-associated viruses. Metagenomic coverage was not correlated with transcriptional activity for several key taxa within Bacteria. Low-light-adapted Prochlorococcus, Synechococcus, and low abundance gamma-proteobacteria enriched in the>3.0-μm size fraction contributed disproportionally to global transcription. The abundance of these groups also correlated with community functions, such as primary production or nitrate uptake. In contrast, many of the most abundant bacterioplankton, including SAR11, SAR86, SAR112 and high-light-adapted Prochlorococcus, exhibited low levels of transcriptional activity and were uncorrelated with rate processes. Eukaryotes such as Haptophytes and non-photosynthetic Aveolates were prevalent in surface samples while Mamielles and Pelagophytes dominated the SCM. Metatranscriptomes generated with ribosomal RNA-depleted mRNA (total mRNA) coupled to in vitro polyadenylation compared with polyA-enriched mRNA revealed a trade-off in detection eukaryotic organelle and eukaryotic nuclear origin transcripts, respectively. Gene expression profiles of SCM eukaryote populations, highly similar in sequence identity to the model pelagophyte Pelagomonas sp. CCMP1756, suggest that pelagophytes are responsible for a majority of nitrate assimilation within the SCM.

  3. Genomes and gene expression across light and productivity gradients in eastern subtropical Pacific microbial communities

    PubMed Central

    Dupont, Chris L; McCrow, John P; Valas, Ruben; Moustafa, Ahmed; Walworth, Nathan; Goodenough, Ursula; Roth, Robyn; Hogle, Shane L; Bai, Jing; Johnson, Zackary I; Mann, Elizabeth; Palenik, Brian; Barbeau, Katherine A; Craig Venter, J; Allen, Andrew E

    2015-01-01

    Transitions in community genomic features and biogeochemical processes were examined in surface and subsurface chlorophyll maximum (SCM) microbial communities across a trophic gradient from mesotrophic waters near San Diego, California to the oligotrophic Pacific. Transect end points contrasted in thermocline depth, rates of nitrogen and CO2 uptake, new production and SCM light intensity. Relative to surface waters, bacterial SCM communities displayed greater genetic diversity and enrichment in putative sulfur oxidizers, multiple actinomycetes, low-light-adapted Prochlorococcus and cell-associated viruses. Metagenomic coverage was not correlated with transcriptional activity for several key taxa within Bacteria. Low-light-adapted Prochlorococcus, Synechococcus, and low abundance gamma-proteobacteria enriched in the>3.0-μm size fraction contributed disproportionally to global transcription. The abundance of these groups also correlated with community functions, such as primary production or nitrate uptake. In contrast, many of the most abundant bacterioplankton, including SAR11, SAR86, SAR112 and high-light-adapted Prochlorococcus, exhibited low levels of transcriptional activity and were uncorrelated with rate processes. Eukaryotes such as Haptophytes and non-photosynthetic Aveolates were prevalent in surface samples while Mamielles and Pelagophytes dominated the SCM. Metatranscriptomes generated with ribosomal RNA-depleted mRNA (total mRNA) coupled to in vitro polyadenylation compared with polyA-enriched mRNA revealed a trade-off in detection eukaryotic organelle and eukaryotic nuclear origin transcripts, respectively. Gene expression profiles of SCM eukaryote populations, highly similar in sequence identity to the model pelagophyte Pelagomonas sp. CCMP1756, suggest that pelagophytes are responsible for a majority of nitrate assimilation within the SCM. PMID:25333462

  4. Millennial-scale precipitation variability over Easter Island (South Pacific) during MIS 3: inter-hemispheric teleconnections with North Atlantic abrupt cold events

    NASA Astrophysics Data System (ADS)

    Margalef, O.; Cacho, I.; Pla-Rabes, S.; Cañellas-Boltà, N.; Pueyo, J. J.; Sáez, A.; Pena, L. D.; Valero-Garcés, B. L.; Rull, V.; Giralt, S.

    2015-04-01

    Marine Isotope Stage 3 (MIS 3, 59.4-27.8 kyr BP) is characterized by the occurrence of rapid millennial-scale climate oscillations known as Dansgaard-Oeschger cycles (DO) and by abrupt cooling events in the North Atlantic known as Heinrich events. Although both the timing and dynamics of these events have been broadly explored in North Atlantic records, the response of the tropical and subtropical latitudes to these rapid climatic excursions, particularly in the Southern Hemisphere, still remains unclear. The Rano Aroi peat record (Easter Island, 27° S) provides a unique opportunity to understand atmospheric and oceanic changes in the South Pacific during these DO cycles because of its singular location, which is influenced by the South Pacific Anticyclone (SPA), the Southern Westerlies (SW), and the Intertropical Convergence Zone (ITCZ) linked to the South Pacific Convergence Zone (SPCZ). The Rano Aroi sequence records 6 major events of enhanced precipitation between 38 and 65 kyr BP. These events are compared with other hydrological records from the tropical and subtropical band supporting a coherent regional picture, with the dominance of humid conditions in Southern Hemisphere tropical band during Heinrich Stadials (HS) 5, 5a and 6 and other Stadials while dry conditions prevailed in the Northern tropics. This antiphased hydrological pattern between hemispheres has been attributed to ITCZ migration, which in turn might be associated with an eastward expansion of the SPCZ storm track, leading to an increased intensity of cyclogenic storms reaching Easter Island. Low Pacific Sea Surface Temperature (SST) gradients across the Equator were coincident with the here-defined Rano Aroi humid events and consistent with a reorganization of Southern Pacific atmospheric and oceanic circulation also at higher latitudes during Heinrich and Dansgaard-Oeschger stadials.

  5. Role of the North Pacific sea surface temperature in the East Asian winter monsoon decadal variability

    NASA Astrophysics Data System (ADS)

    Sun, Jianqi; Wu, Sha; Ao, Juan

    2016-06-01

    In this study, a possible mechanism for the decadal variability in the East Asian winter monsoon (EAWM) is proposed. Specifically, the North Pacific sea surface temperature (SST) may play an important role. An analysis of the observations shows that the North Pacific SST has a remarkable decadal pattern whose phase shifted around the mid-1980s. This North Pacific SST decadal pattern can weaken the East Asian trough and enhance the North Pacific Oscillation through changing air-sea interactions over the North Pacific. The weak East Asian trough enhances the zonal circulation and weakens the meridional circulation over East Asia, consequently leading to a weaker southward cold surge and East Asia warming around the mid-1980s. The numerical experiment further confirms the pronounced physical processes. In addition, over the longer period of 1871-2012, the indices of the EAWM and North Pacific SST decadal pattern are also highly consistent on the decadal timescale, which further confirms the impact of the North Pacific SST decadal pattern on the EAWM decadal variability.

  6. Annual cycles of deep-ocean biogeochemical export fluxes in subtropical and subantarctic waters, southwest Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Nodder, Scott D.; Chiswell, Stephen M.; Northcote, Lisa C.

    2016-04-01

    The annual cycles of particle fluxes derived from moored sediment trap data collected during 2000-2012 in subtropical (STW) and subantarctic waters (SAW) east of New Zealand are presented. These observations are the most comprehensive export flux time series from temperate Southern Hemisphere latitudes to date. With high levels of variability, fluxes in SAW were markedly lower than in STW, reflecting the picophytoplankton-dominated communities in the iron-limited, high nutrient-low chlorophyll SAW. Austral spring chlorophyll blooms in surface STW were near synchronous with elevated fluxes of bio-siliceous, carbonate, and organic carbon-rich materials to the deep ocean, probably facilitated by diatom and/or coccolithophorid sedimentation. Lithogenic fluxes were also high in STW, compared to SAW, reflecting proximity to the New Zealand landmass. In contrast, the highest biogenic fluxes in SAW occurred in spring when surface chlorophyll concentrations were low, while highest annual chlorophyll concentrations were in summer with no associated flux increase. We hypothesize that the high spring export in SAW results from subsurface chlorophyll accumulation that is not evident from remote-sensing satellites. This material was also rich in biogenic silica, perhaps related to the preferential export of diatoms and other silica-producing organisms, such as silicoflagellates and radiolarians. Organic carbon fluxes in STW are similar to that of other mesotrophic to oligotrophic waters (˜6-7 mg C m-2 d-1), whereas export from SAW is below the global average (˜3 mg C m-2 d-1). Regional differences in flux across the SW Pacific and Tasman region reflect variations in physical processes and ecosystem structure and function.

  7. Influence of the Western Pacific teleconnection pattern on Western North Pacific tropical cyclone activity

    NASA Astrophysics Data System (ADS)

    Choi, Ki-Seon; Moon, Il-Ju

    2012-09-01

    This study analyzes the characteristics of Western North Pacific (WNP) tropical cyclone (TC) activity and large-scale environments according to the Western Pacific (WP) teleconnection pattern in summer. In the positive WP phase, an anomalous cyclone and an anomalous anticyclone develop in the low and middle latitudes of the East Asia area, respectively. As a result, southeasterlies are reinforced in the northeast area of East Asia (including Korea and Japan), which facilitates the movement of TC to this area, whereas northwesterlies are reinforced in the southwest area of East Asia (including southern China and the Indochina Peninsula) which blocks the movement of TC to that area. Due to the spatial distribution of this reinforced pressure system, TCs that develop during the positive WP phase move and turn more to the northeast of the WNP than TCs which develop during the negative WP phase. The characteristics of this TC activity during the positive WP phase are associated with the upper tropospheric jet being located farther to the northeast. TCs during the negative WP phase mainly move to the west from the Philippines toward southern China and the Indochina Peninsula. Due to the terrain effect caused by the passage of TCs in mainland China, the intensity of TCs during the negative WP phase is weaker than those during the positive WP phase.

  8. Change of tropical cyclone activity by Pacific-Japan teleconnection pattern in the western North Pacific

    NASA Astrophysics Data System (ADS)

    Choi, Ki-Seon; Wu, Chun-Chieh; Cha, Eun-Jeong

    2010-10-01

    This study shows that the Pacific-Japan (PJ) teleconnection pattern has a significant influence on tropical cyclone (TC) activities over the western North Pacific (WNP) during the boreal summer (July, August, and September). During positive (negative) PJ phase, TCs form at a more northward (southward) location, recurve at a more northeastward (southwestward) location, and frequently pass over the northeast Asian (southeast Asian) region, including Korea and Japan (South China Sea and southern China). In particular, this difference in the TC track between the two phases is observed as a dipole-like pattern between the regions of Southeast and Northeast Asia. The TC characteristics during the positive PJ phase are caused by the following two stronger atmospheric circulations over the WNP: an anticyclonic circulation centered to the east of Japan and a cyclonic circulation centered to the east of Taiwan. The southeasterly between these two circulations serves as steering flow that TCs move northward toward Korea and Japan from the northeast of the Philippines. Conversely, TCs during the negative PJ phase mainly move westward toward the South China Sea and southern China by the easterly from a stronger anticyclonic circulation centered to the east of Taiwan. As a result of this feature of TC track during the negative PJ phase, TC lifetime is shorter and TC intensity is weaker.

  9. Effect of subtropical mode water on the decadal variability of the subsurface transport through the Luzon Strait in the western Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Yu, Kai; Qu, Tangdong; Dong, Changming; Yan, Youfang

    2015-10-01

    Analysis of the 62 year hindcast outputs from an eddy-resolving ocean general circulation model shows a good correspondence of the Luzon Strait subsurface transport to the Pacific Decadal Oscillation (PDO) index on a decadal time scale, with the latter leading by about 5 years. The backward particle tracing experiments indicate that the part of the subsurface water in the Luzon Strait generated by the subduction processes comes from the Subtropical Mode Water (STMW). The model results also show a strong PDO signal in the subduction rate, as well as the subsurface low potential vorticity (PV), in the formation region of the STMW, and these decadal signals can be traced all the way to the Luzon Strait as PV anomalies follow the subtropical gyre circulation in about 5 years. The PV anomalies from the STMW affect the subsurface net transport in the Luzon Strait through changing the subsurface density structure and then zonal velocity.

  10. The flooding of Beringia and North Pacific Intermediate Water formation

    NASA Astrophysics Data System (ADS)

    Davies, M. H.; Mix, A. C.; Stoner, J. S.; Southon, J. R.; Cheseby, M.; Xuan, C.

    2011-12-01

    We reconstruct Northeast Pacific paleoventilation over the last 17,000 ybp from radiocarbon dates in a sediment core (EW0408-85JC) 682 m deep on the Southeast Alaska margin, evaluating the implications of three standard chronologies: 1) calibrated planktonic foraminiferal 14C dates assuming a constant reservoir correction, 2) calibrated benthic foraminiferal 14C dates assuming a constant reservoir correction, and 3) correlation of δ18O in planktonic foraminifera (N. pachyderma sinistral) to δ18O in a layer-counted Greenland ice core (NGRIP). The assumption of constant benthic reservoir age implies negative reservoir ages for coexisting planktonic foraminifera during deglaciation, and is rejected. The δ18O-tuned age model reproduces two episodes of extremely old intermediate water, similar to those inferred during Termination 1 off Baja California (Marchitto et al., 2007), but predicts co-varying reservoir ages for planktonic foraminifera of >2,500 years. Such very high planktonic reservoir ages, on a predominantly downwelling margin, may imply the apparent subsurface ventilation anomalies are an artifact of the age model tuning. The age model based on calibrated planktonic dates indicates a modest increase in intermediate water reservoir age to 2,670 ± 180 during Termination 1, implying reduced ventilation prior to the Holocene. A shift to lower ventilation ages at ~10,500 cal ybp is coeval with flooding of Beringia (Elias et al., 1996), suggesting that flooded shelves and net northward export of low-salinity surface waters through Bering Strait enhanced ventilation of the North Pacific in the early Holocene.

  11. A definition for rapid weakening of North Atlantic and eastern North Pacific tropical cyclones

    NASA Astrophysics Data System (ADS)

    Wood, Kimberly M.; Ritchie, Elizabeth A.

    2015-11-01

    Periods of 24 h over-water weakening during 1982-2013 for North Atlantic (NAL) and eastern North Pacific (ENP) tropical cyclones (TCs) are examined to determine a threshold for rapid weakening (RW). These periods are defined by consistent weakening while the TC center remained more than 50 km from land. Weakening thresholds of 25, 30, and 35 kt represent the 87th (69th), 94th (80th), and 97th (89th) percentile in the NAL (ENP). Based on these statistics, the 30 kt threshold is chosen to define RW. Compared to all weakening periods, RW events are generally associated with greater 24 h official forecast errors, and these errors tend to be overestimates in both basins. These events usually occur as the TC crosses a sharp sea surface temperature gradient, encounters greater vertical wind shear, and entrains drier air. These metrics may be useful to forecasters assessing the likelihood of RW.

  12. The cycling of iron, zinc and cadmium in the North East Pacific Ocean - Insights from stable isotopes

    NASA Astrophysics Data System (ADS)

    Conway, Tim M.; John, Seth G.

    2015-09-01

    Dissolved stable isotope ratios of the transition metals provide useful information, both for understanding the cycling of these bioactive trace elements through the oceans, and tracing their marine sources and sinks. Here, we present seawater dissolved Fe, Zn and Cd concentration and stable isotope ratio (δ56Fe, δ66Zn, and δ114Cd) profiles from two stations in the Pacific Ocean, the SAFe Station (30°N 140°W) in the subtropical North East Pacific from the GEOTRACES IC2 cruise, and the marginal San Pedro Basin (33.8°N 118.4°W) within the South California Bight. These data represent, to our knowledge, the first full-water column profiles for δ66Zn and δ56Fe from the open-ocean North Pacific, and the first observations of dissolved δ66Zn and δ114Cd in a low-oxygen marginal basin. At the SAFe station, δ56Fe is isotopically lighter throughout the water column (-0.6 to +0.1‰, relative to IRRM-014) compared to the North Atlantic, suggesting significant differences in Fe sources or Fe cycling between these two ocean basins. A broad minimum in δ56Fe associated with the North Pacific oxygen minimum zone (OMZ; <75 μmol kg-1 dissolved oxygen; ∼550-2000 m depth) is consistent with reductive sediments along the California margin being an important source of dissolved Fe to the North Pacific. Other processes which may influence δ56Fe at SAFe include biological cycling in the upper ocean, and input of Fe from hydrothermal vents and oxic sediments below the OMZ. Zn and Cd concentration profiles at both stations broadly match the distribution of the macronutrients silicate and phosphate, respectively. At SAFe, δ114Cd increases towards the surface, reflecting the biological preference for assimilation of lighter Cd isotopes, while negative Cd∗ (-0.12) associated with low oxygen waters supports the recently proposed hypothesis of water-column CdS precipitation. In contrast to δ114Cd, δ66Zn at SAFe decreases towards the surface ocean, perhaps due to scavenging

  13. Slowing down of North Pacific climate variability and its implications for abrupt ecosystem change.

    PubMed

    Boulton, Chris A; Lenton, Timothy M

    2015-09-15

    Marine ecosystems are sensitive to stochastic environmental variability, with higher-amplitude, lower-frequency--i.e., "redder"--variability posing a greater threat of triggering large ecosystem changes. Here we show that fluctuations in the Pacific Decadal Oscillation (PDO) index have slowed down markedly over the observational record (1900-present), as indicated by a robust increase in autocorrelation. This "reddening" of the spectrum of climate variability is also found in regionally averaged North Pacific sea surface temperatures (SSTs), and can be at least partly explained by observed deepening of the ocean mixed layer. The progressive reddening of North Pacific climate variability has important implications for marine ecosystems. Ecosystem variables that respond linearly to climate forcing will have become prone to much larger variations over the observational record, whereas ecosystem variables that respond nonlinearly to climate forcing will have become prone to more frequent "regime shifts." Thus, slowing down of North Pacific climate variability can help explain the large magnitude and potentially the quick succession of well-known abrupt changes in North Pacific ecosystems in 1977 and 1989. When looking ahead, despite model limitations in simulating mixed layer depth (MLD) in the North Pacific, global warming is robustly expected to decrease MLD. This could potentially reverse the observed trend of slowing down of North Pacific climate variability and its effects on marine ecosystems.

  14. Slowing down of North Pacific climate variability and its implications for abrupt ecosystem change

    PubMed Central

    Boulton, Chris A.; Lenton, Timothy M.

    2015-01-01

    Marine ecosystems are sensitive to stochastic environmental variability, with higher-amplitude, lower-frequency––i.e., “redder”––variability posing a greater threat of triggering large ecosystem changes. Here we show that fluctuations in the Pacific Decadal Oscillation (PDO) index have slowed down markedly over the observational record (1900–present), as indicated by a robust increase in autocorrelation. This “reddening” of the spectrum of climate variability is also found in regionally averaged North Pacific sea surface temperatures (SSTs), and can be at least partly explained by observed deepening of the ocean mixed layer. The progressive reddening of North Pacific climate variability has important implications for marine ecosystems. Ecosystem variables that respond linearly to climate forcing will have become prone to much larger variations over the observational record, whereas ecosystem variables that respond nonlinearly to climate forcing will have become prone to more frequent “regime shifts.” Thus, slowing down of North Pacific climate variability can help explain the large magnitude and potentially the quick succession of well-known abrupt changes in North Pacific ecosystems in 1977 and 1989. When looking ahead, despite model limitations in simulating mixed layer depth (MLD) in the North Pacific, global warming is robustly expected to decrease MLD. This could potentially reverse the observed trend of slowing down of North Pacific climate variability and its effects on marine ecosystems. PMID:26324900

  15. Variability in transport processes of Pacific saury Cololabis saira larvae leading to their broad dispersal: Implications for their ecological role in the western North Pacific

    NASA Astrophysics Data System (ADS)

    Oozeki, Yoshioki; Okunishi, Takeshi; Takasuka, Akinori; Ambe, Daisuke

    2015-11-01

    Transport of Pacific saury Cololabis saira larvae from spawning to nursery grounds was examined based on datasets from larval distribution surveys during winter seasons 1990-2011. In the surveys, a neuston net was towed for 10 min over broad areas off the southern Pacific coast of Japan. Transport trajectories of saury larvae and temperature they experienced were analyzed based on a numerical particle-tracking model from 1993 to 2011 using satellite-based sea surface current and temperature data. Larval growth during the transport was estimated from the relationship of larval growth to environmental factors obtained in a previous study. Results of the particle tracking experiments indicated that a large amount of saury juveniles (knob length, KnL, 40 mm) were transported to an area south of the Kuroshio axis. Only a relatively small amount (14.6%) of the 40 mm KnL stage juveniles were transported in and around the Kuroshio extension, although it has previously been considered important that the juveniles are transported to the area north of the Kuroshio extension. Abundance of juveniles transported to the area north of the Kuroshio extension indicated a positive relationship to the abundance of medium size class saury in the autumn fishing season. Even though a very small part (3.9%) of hatched larvae were transported to this area, recruitment of the saury population depends on this amount of transported hatched larvae. On the other hand, the high juvenile transport rate to the areas south of the Kuroshio axis may suggest a broad dispersal mechanism to ensure that some larvae find a suitable habitat. Subsequently, the importance of saury in the marine ecosystem as a food item for predatory species in the sub-tropical region is discussed.

  16. The Tropical Pacific and Sub-Arctic Weather in North America

    NASA Astrophysics Data System (ADS)

    Hartmann, D. L.

    2015-12-01

    In addition to the classical El Niño, other structures in tropical Pacific SST anomalies have a strong influence on extratropical weather. Since 1979 the second EOF of global SST is a mode with warm SST in the western equatorial Pacific and cool SST in the eastern equatorial Pacific. This pattern has a strong signal in the extratropical North Pacific associated with the Rossby wave anomalies that are forced in the tropics and propagate over North America, and has been termed the North Pacific Mode. This mode is associated with a ridge on the west coast of North American and a trough downstream of the Rocky Mountains. This mode of variability had a strong influence on the winters of 2014 and 2015, and appears to have played a strong role in the cold winter of 2014 in central and eastern North America. This pattern persisted from the middle of 2013 through at least July of 2015, and also seems to have an effect on summer weather anomalies of the same nature. In the past the strength of the North Pacific Mode has preceded strong El Niño events, after which point it went into a strongly negative phase. This history suggests a transition to a more classical El Niño anomaly pattern for the winter of 2016, which would produce a warmer winter in central and eastern North America and cool and moist conditions over the Gulf of Mexico.

  17. Subtropical versus subpolar freshwater routing: The pathways of icebergs and meltwater in the North Atlantic during deglaciation

    NASA Astrophysics Data System (ADS)

    Condron, A.; Hill, J. C.

    2015-12-01

    Marine sediment records reveal episodes of increased ice rafted debris (IRD) to the subpolar N. Atlantic (40N-50N) during deglaciation that are linked to the calving of enormous numbers of icebergs from the Northern Hemisphere ice sheets. There is considerable interest, and uncertainty, as to whether meltwater from these icebergs freshened the ocean sufficiently to weaken the Atlantic Meridional Overturning Circulation (AMOC). Very recently, hundreds of iceberg scours have been observed along the east coast of the United States as far south as Florida. The iceberg scours are oriented SSW along the coast and are observed in water depths up to several hundred meters deep, indicating that massive (up to 300m thick) icebergs once drifted along the east coast of N. America into the subtropics during deglaciation. A newly developed iceberg model (MITberg) is coupled to an eddy-permitting ocean model to show that icebergs are carried south to Florida by coastally-confined meltwater currents caused by the sudden release of large volumes of meltwater from Hudson Bay and/or Gulf of St. Lawrence. When meltwater fluxes exceed 2.5Sv simulated icebergs drift as far south as Miami, Florida, and thousands are carried into the center of the subtropical gyre by narrow meltwater filaments and instabilities along the boundary current. When the meltwater flood ends, icebergs can no longer drift into the subtropics, and quickly become confined to the subpolar gyre where the majority of IRD is found. Our results indicate that icebergs and meltwater from the north did not always directly freshening the subpolar gyre, but were periodically transported south of the main subpolar deep water formation regions that regulate AMOC strength and climate. Dating the observed iceberg scours will tell us exactly how active and persistent this coastally-confined meltwater pathway was during deglaciation and help us unravel why there is not always a clear relationship between increased high latitude

  18. Ammonia and nitrite oxidation in the Eastern Tropical North Pacific

    NASA Astrophysics Data System (ADS)

    Peng, Xuefeng; Fuchsman, Clara A.; Jayakumar, Amal; Oleynik, Sergey; Martens-Habbena, Willm; Devol, Allan H.; Ward, Bess B.

    2015-12-01

    Nitrification plays a key role in the marine nitrogen (N) cycle, including in oceanic oxygen minimum zones (OMZs), which are hot spots for denitrification and anaerobic ammonia oxidation (anammox). Recent evidence suggests that nitrification links the source (remineralized organic matter) and sink (denitrification and anammox) of fixed N directly in the steep oxycline in the OMZs. We performed shipboard incubations with 15N tracers to characterize the depth distribution of nitrification in the Eastern Tropical North Pacific (ETNP). Additional experiments were conducted to investigate photoinhibition. Allylthiourea (ATU) was used to distinguish the contribution of archaeal and bacterial ammonia oxidation. The abundance of archaeal and β-proteobacterial ammonia monooxygenase gene subunit A (amoA) was determined by quantitative polymerase chain reaction. The rates of ammonia and nitrite oxidation showed distinct subsurface maxima, with the latter slightly deeper than the former. The ammonia oxidation maximum coincided with the primary nitrite concentration maximum, archaeal amoA gene maximum, and the subsurface nitrous oxide maximum. Negligible rates of ammonia oxidation were found at anoxic depths, where high rates of nitrite oxidation were measured. Archaeal amoA gene abundance was generally 1 to 2 orders of magnitude higher than bacterial amoA gene abundance, and inhibition of ammonia-oxidizing bacteria with 10 μM ATU did not affect ammonia oxidation rates, indicating the dominance of archaea in ammonia oxidation. These results depict highly dynamic activities of ammonia and nitrite oxidation in the oxycline of the ETNP OMZ.

  19. Northern fulmars as biological monitors of trends of plastic pollution in the eastern North Pacific.

    PubMed

    Avery-Gomm, Stephanie; O'Hara, Patrick D; Kleine, Lydia; Bowes, Victoria; Wilson, Laurie K; Barry, Karen L

    2012-09-01

    Marine plastic debris is a global issue, which highlights the need for internationally standardized methods of monitoring plastic pollution. The stomach contents of beached northern fulmar (Fulmarus glacialis) have proven a cost-effective biomonitor in Europe. However, recent information on northern fulmar plastic ingestion is lacking in the North Pacific. We quantified the stomach contents of 67 fulmars from beaches in the eastern North Pacific in 2009-2010 and found that 92.5% of fulmars had ingested an average of 36.8 pieces, or 0.385 g of plastic. Plastic ingestion in these fulmars is among the highest recorded globally. Compared to earlier studies in the North Pacific, our findings indicate an increase in plastic ingestion over the past 40 years. This study substantiates the use of northern fulmar as biomonitors of plastic pollution in the North Pacific and suggests that the high levels of plastic pollution in this region warrant further monitoring.

  20. The way we were: surgical practice at the dawn of the North Pacific Surgical Association.

    PubMed

    Carter, Preston L

    2014-05-01

    The North Pacific Surgical Association Historian's centennial lecture, with review of the geographic challenges for members of this society at the time of its founding and selected insights into surgical practices and philosophies of a century ago.

  1. Nitrogen fixation in an anticyclonic eddy in the oligotrophic North Pacific Ocean.

    PubMed

    Fong, Allison A; Karl, David M; Lukas, Roger; Letelier, Ricardo M; Zehr, Jonathan P; Church, Matthew J

    2008-06-01

    Mesoscale physical processes (for example eddies, frontal meanders and planetary waves) can play important roles in controlling ocean biogeochemistry. We examined spatial variations in upper ocean (0-100 m) nutrient inventories, N(2) fixing microorganism diversity and abundance, and rates of N(2) fixation in an anticyclonic eddy near Station ALOHA (22 degrees 45' N, 158 degrees 00' W) in the North Pacific Subtropical Gyre (NPSG). In July 2005, satellite-based sea surface altimetry and ocean color observation revealed an anticyclonic eddy with enhanced chlorophyll in the upper ocean in the vicinity of Station ALOHA. Within the eddy, near-surface ocean chlorophyll concentrations were approximately 5-fold greater than in the surrounding waters. Inventories of nitrate and phosphate in the eddy were similar to the concentrations historically observed at Station ALOHA, while silicic acid inventories were significantly depleted (one-way analysis of variance, P<0.01). Quantitative PCR determinations of nifH gene copies revealed relatively high abundances of several N(2) fixing cyanobacteria, including Trichodesmium spp., Crocosphaera watsonii and Richelia intracellularis. Reverse transcriptase PCR (RT-PCR) amplified nitrogenase (nifH) gene transcripts were cloned and sequenced to examine the diversity of active N(2) fixing microorganisms; these clone libraries were dominated by sequence-types 97%-99% identical to the filamentous cyanobacteria Trichodesmium spp. Near-surface ocean rates of N(2) fixation were 2-18 times greater (averaging 8.6+/-5.6 nmol N per l per day) than previously reported measurements at Station ALOHA. These results suggest that mesoscale physical variability can play an important role in modifying the abundances of N(2) fixing microorganisms and associated rates of N(2) fixation in open ocean ecosystems.

  2. Comparative Assessment of Nitrogen Fixation Methodologies, Conducted in the Oligotrophic North Pacific Ocean

    PubMed Central

    Böttjer, Daniela; Church, Matthew J.; Karl, David M.

    2012-01-01

    Resolution of the nitrogen (N) cycle in the marine environment requires an accurate assessment of dinitrogen (N2) fixation. We present here an update on progress in conducting field measurements of acetylene reduction (AR) and 15N2 tracer assimilation in the oligotrophic North Pacific Subtropical Gyre (NPSG). The AR assay was conducted on discrete seawater samples using a headspace analysis system, followed by quantification of ethylene (C2H4) with a reducing compound photodetector. The rates of C2H4 production were measurable for nonconcentrated seawater samples after an incubation period of 3 to 4 h. The 15N2 tracer measurements compared the addition of 15N2 as a gas bubble and dissolved as 15N2 enriched seawater. On all sampling occasions and at all depths, a 2- to 6-fold increase in the rate of 15N2 assimilation was measured when 15N2-enriched seawater was added to the seawater sample compared to the addition of 15N2 as a gas bubble. In addition, we show that the 15N2-enriched seawater can be prepared prior to its use with no detectable loss (<1.7%) of dissolved 15N2 during 4 weeks of storage, facilitating its use in the field. The ratio of C2H4 production to 15N2 assimilation varied from 7 to 27 when measured simultaneously in surface seawater samples. Collectively, the modifications to the AR assay and the 15N2 assimilation technique present opportunities for more accurate and high frequency measurements (e.g., diel scale) of N2 fixation, providing further insight into the contribution of different groups of diazotrophs to the input of N in the global oceans. PMID:22773638

  3. Predictable and efficient carbon sequestration in the North Pacific Ocean supported by symbiotic nitrogen fixation

    PubMed Central

    Karl, David M.; Church, Matthew J.; Dore, John E.; Letelier, Ricardo M.; Mahaffey, Claire

    2012-01-01

    The atmospheric and deep sea reservoirs of carbon dioxide are linked via physical, chemical, and biological processes. The last of these include photosynthesis, particle settling, and organic matter remineralization, and are collectively termed the “biological carbon pump.” Herein, we present results from a 13-y (1992–2004) sediment trap experiment conducted in the permanently oligotrophic North Pacific Subtropical Gyre that document a large, rapid, and predictable summertime (July 15–August 15) pulse in particulate matter export to the deep sea (4,000 m). Peak daily fluxes of particulate matter during the summer export pulse (SEP) average 408, 283, 24.1, 1.1, and 67.5 μmol·m−2·d−1 for total carbon, organic carbon, nitrogen, phosphorus (PP), and biogenic silica, respectively. The SEP is approximately threefold greater than mean wintertime particle fluxes and fuels more efficient carbon sequestration because of low remineralization during downward transit that leads to elevated total carbon/PP and organic carbon/PP particle stoichiometry (371:1 and 250:1, respectively). Our long-term observations suggest that seasonal changes in the microbial assemblage, namely, summertime increases in the biomass and productivity of symbiotic nitrogen-fixing cyanobacteria in association with diatoms, are the main cause of the prominent SEP. The recurrent SEP is enigmatic because it is focused in time despite the absence of any obvious predictable stimulus or habitat condition. We hypothesize that changes in day length (photoperiodism) may be an important environmental cue to initiate aggregation and subsequent export of organic matter to the deep sea. PMID:22308450

  4. Comparative assessment of nitrogen fixation methodologies, conducted in the oligotrophic North Pacific Ocean.

    PubMed

    Wilson, Samuel T; Böttjer, Daniela; Church, Matthew J; Karl, David M

    2012-09-01

    Resolution of the nitrogen (N) cycle in the marine environment requires an accurate assessment of dinitrogen (N(2)) fixation. We present here an update on progress in conducting field measurements of acetylene reduction (AR) and (15)N(2) tracer assimilation in the oligotrophic North Pacific Subtropical Gyre (NPSG). The AR assay was conducted on discrete seawater samples using a headspace analysis system, followed by quantification of ethylene (C(2)H(4)) with a reducing compound photodetector. The rates of C(2)H(4) production were measurable for nonconcentrated seawater samples after an incubation period of 3 to 4 h. The (15)N(2) tracer measurements compared the addition of (15)N(2) as a gas bubble and dissolved as (15)N(2) enriched seawater. On all sampling occasions and at all depths, a 2- to 6-fold increase in the rate of (15)N(2) assimilation was measured when (15)N(2)-enriched seawater was added to the seawater sample compared to the addition of (15)N(2) as a gas bubble. In addition, we show that the (15)N(2)-enriched seawater can be prepared prior to its use with no detectable loss (<1.7%) of dissolved (15)N(2) during 4 weeks of storage, facilitating its use in the field. The ratio of C(2)H(4) production to (15)N(2) assimilation varied from 7 to 27 when measured simultaneously in surface seawater samples. Collectively, the modifications to the AR assay and the (15)N(2) assimilation technique present opportunities for more accurate and high frequency measurements (e.g., diel scale) of N(2) fixation, providing further insight into the contribution of different groups of diazotrophs to the input of N in the global oceans. PMID:22773638

  5. Distribution patterns and phylogeny of marine stramenopiles in the north pacific ocean.

    PubMed

    Lin, Yun-Chi; Campbell, Tracy; Chung, Chih-Ching; Gong, Gwo-Ching; Chiang, Kuo-Ping; Worden, Alexandra Z

    2012-05-01

    Marine stramenopiles (MASTs) are a diverse suite of eukaryotic microbes found in marine environments. Several MAST lineages are thought to contain heterotrophic nanoflagellates. However, MASTs remain uncultured and data on distributions and trophic modes are limited. We investigated MASTs in provinces on the west and east sides of the North Pacific Subtropical Gyre, specifically the East China Sea (ECS) and the California Current system (CALC). For each province, DNA was sampled from three zones: coastal, mesotrophic transitional, and more oligotrophic euphotic waters. Along with diatoms, chrysophytes, and other stramenopiles, sequences were recovered from nine MAST lineages in the six ECS and four CALC 18S rRNA gene clone libraries. All but one of these libraries were from surface samples. MAST clusters 1, 3, 7, 8, and 11 were identified in both provinces, with MAST cluster 3 (MAST-3) being found the most frequently. Additionally, MAST-2 was detected in the ECS and MAST-4, -9, and -12 were detected in the CALC. Phylogenetic analysis indicated that some subclades within these lineages differ along latitudinal gradients. MAST-1A, -1B, and -1C and MAST-4 size and abundance estimates obtained using fluorescence in situ hybridization on 79 spring and summer ECS samples showed a negative correlation between size of MAST-1B and MAST-4 cells and temperature. MAST-1A was rarely detected, but MAST-1B and -1C and MAST-4 were abundant in summer and MAST-1C and MAST-4 were more so at the coast, with maximum abundances of 543 and 1,896 cells ml(-1), respectively. MAST-4 and Synechococcus abundances were correlated, and experimental work showed that MAST-4 ingests Synechococcus. Together with previous studies, this study helps refine hypotheses on distribution and trophic modes of MAST lineages.

  6. Light dependence of [3H]leucine incorporation in the oligotrophic North Pacific ocean.

    PubMed

    Church, Matthew J; Ducklow, Hugh W; Karl, David M

    2004-07-01

    The influence of irradiance on bacterial incorporation of [(3)H]leucine was evaluated at Station ALOHA in the oligotrophic North Pacific subtropical gyre. Six experiments were conducted on three cruises to Station ALOHA to examine how [(3)H]leucine incorporation varied as a function of irradiance. Two experiments were also conducted to assess the photoautotrophic response to irradiance (based on photosynthetic uptake of [(14)C]bicarbonate) in both the upper and lower photic zones. Rates of [(3)H]leucine incorporation responded to irradiance in a photosynthesis-like manner, increasing sharply at low light and then saturating and sometimes declining with increasing light intensity. The influence of irradiance on bacterial growth was evaluated in both the well-lit (5 to 25 m) and dimly lit regions of the upper ocean (75 to 100 m) to determine whether the bacterial response to irradiance differed along the depth-dependent light gradient of the photic zone. [(3)H]leucine incorporation rates were analyzed with a photosynthesis-irradiance model for a quantitative description of the relationships between [(3)H]leucine incorporation and irradiance. Maximum rates of [(3)H]leucine incorporation in the upper photic zone increased 48 to 92% relative to those of dark-incubated samples, with [(3)H]leucine incorporation saturating at light intensities between 58 and 363 micromol of quanta m(-2) s(-1). Rates of [(3)H]leucine incorporation in the deep photic zone were photostimulated 53 to 114% and were susceptible to photoinhibition, with rates declining at light intensities of >100 micromol of quanta m(-2) s(-1). The results of these experiments revealed that sunlight directly influences bacterial growth in this open-ocean ecosystem.

  7. Ocean-to-Ocean Dissimilarities of Salty Subtropical Surface Water

    NASA Astrophysics Data System (ADS)

    Gordon, A. L.

    2014-12-01

    Each ocean basin displays its own 'personality', reflecting its degree of isolation or connectivity to the global ocean, its place in the interocean exchange network and associated ocean overturning circulation systems, as well as regional circulation and air-sea exchange patterns. While dissimilarities are most notable in the northern hemisphere (the salty North Atlantic vs the fresher North Pacific; as well as the salty Arabian and the fresher Bay of Bengal, a miniature Atlantic/Pacific analog?) far removed from the grand equalizing interocean link of the circum-Antarctic belt, and where large continental blocks impose contrasting forcing, the southern hemisphere ocean basins also display differences. Ocean to ocean dissimilarities are evident in the dry subtropical climate belt, marked by deserts on land and salty surface ocean water. The subtropical sea surface salinity maximum (SSS-max) patterns of 5 the subtropical regimes (the North and South Atlantic, North and South Pacific, and the southern Indian Ocean) display significant dissimilarities in their relative position within their ocean basin, in the structure and seasonality of the SSS-max pattern. The near synoptic coverage of Aquarius and Argo profilers are further defining interannual variability. The South Atlantic SSS-max is pressed against the western boundary, whereas in the other regimes the SSS-max falls within the eastern half of the ocean basin, though the western South Pacific displays a secondary SSS-max. For further details see: A. Gordon, C. Giulivi, J. Busecke, F. Bingham, submitted to the SPURS Oceanography special issue.

  8. Comparison of phosphate uptake rates by the smallest plastidic and aplastidic protists in the North Atlantic subtropical gyre.

    PubMed

    Hartmann, Manuela; Grob, Carolina; Scanlan, David J; Martin, Adrian P; Burkill, Peter H; Zubkov, Mikhail V

    2011-11-01

    The smallest phototrophic protists (<3 μm) are important primary producers in oligotrophic subtropical gyres - the Earth's largest ecosystems. In order to elucidate how these protists meet their inorganic nutrient requirements, we compared the phosphate uptake rates of plastidic and aplastidic protists in the phosphate-depleted subtropical and tropical North Atlantic (4-29°N) using a combination of radiotracers and flow cytometric sorting on two Atlantic Meridional Transect cruises. Plastidic protists were divided into two groups according to their size (<2 and 2-3 μm). Both groups of plastidic protists showed higher phosphate uptake rates per cell than the aplastidic protists. Although the phosphate uptake rates of protist cells were on average seven times (P<0.001) higher than those of bacterioplankton, the biomass-specific phosphate uptake rates of protists were one fourth to one twentieth of an average bacterioplankton cell. The unsustainably low biomass-specific phosphate uptake by both plastidic and aplastidic protists suggests the existence of a common alternative means of phosphorus acquisition - predation on phosphorus-rich bacterioplankton cells. PMID:21696408

  9. Comparison of phosphate uptake rates by the smallest plastidic and aplastidic protists in the North Atlantic subtropical gyre.

    PubMed

    Hartmann, Manuela; Grob, Carolina; Scanlan, David J; Martin, Adrian P; Burkill, Peter H; Zubkov, Mikhail V

    2011-11-01

    The smallest phototrophic protists (<3 μm) are important primary producers in oligotrophic subtropical gyres - the Earth's largest ecosystems. In order to elucidate how these protists meet their inorganic nutrient requirements, we compared the phosphate uptake rates of plastidic and aplastidic protists in the phosphate-depleted subtropical and tropical North Atlantic (4-29°N) using a combination of radiotracers and flow cytometric sorting on two Atlantic Meridional Transect cruises. Plastidic protists were divided into two groups according to their size (<2 and 2-3 μm). Both groups of plastidic protists showed higher phosphate uptake rates per cell than the aplastidic protists. Although the phosphate uptake rates of protist cells were on average seven times (P<0.001) higher than those of bacterioplankton, the biomass-specific phosphate uptake rates of protists were one fourth to one twentieth of an average bacterioplankton cell. The unsustainably low biomass-specific phosphate uptake by both plastidic and aplastidic protists suggests the existence of a common alternative means of phosphorus acquisition - predation on phosphorus-rich bacterioplankton cells.

  10. Estimating historical eastern North Pacific blue whale catches using spatial calling patterns.

    PubMed

    Monnahan, Cole C; Branch, Trevor A; Stafford, Kathleen M; Ivashchenko, Yulia V; Oleson, Erin M

    2014-01-01

    Blue whales (Balaenoptera musculus) were exploited extensively around the world and remain endangered. In the North Pacific their population structure is unclear and current status unknown, with the exception of a well-studied eastern North Pacific (ENP) population. Despite existing abundance estimates for the ENP population, it is difficult to estimate pre-exploitation abundance levels and gauge their recovery because historical catches of the ENP population are difficult to separate from catches of other populations in the North Pacific. We collated previously unreported Soviet catches and combined these with known catches to form the most current estimates of North Pacific blue whale catches. We split these conflated catches using recorded acoustic calls from throughout the North Pacific, the knowledge that the ENP population produces a different call than blue whales in the western North Pacific (WNP). The catches were split by estimating spatiotemporal occurrence of blue whales with generalized additive models fitted to acoustic call patterns, which predict the probability a catch belonged to the ENP population based on the proportion of calls of each population recorded by latitude, longitude, and month. When applied to the conflated historical catches, which totaled 9,773, we estimate that ENP blue whale catches totaled 3,411 (95% range 2,593 to 4,114) from 1905-1971, and amounted to 35% (95% range 27% to 42%) of all catches in the North Pacific. Thus most catches in the North Pacific were for WNP blue whales, totaling 6,362 (95% range 5,659 to 7,180). The uncertainty in the acoustic data influence the results substantially more than uncertainty in catch locations and dates, but the results are fairly insensitive to the ecological assumptions made in the analysis. The results of this study provide information for future studies investigating the recovery of these populations and the impact of continuing and future sources of anthropogenic mortality. PMID

  11. Estimating historical eastern North Pacific blue whale catches using spatial calling patterns.

    PubMed

    Monnahan, Cole C; Branch, Trevor A; Stafford, Kathleen M; Ivashchenko, Yulia V; Oleson, Erin M

    2014-01-01

    Blue whales (Balaenoptera musculus) were exploited extensively around the world and remain endangered. In the North Pacific their population structure is unclear and current status unknown, with the exception of a well-studied eastern North Pacific (ENP) population. Despite existing abundance estimates for the ENP population, it is difficult to estimate pre-exploitation abundance levels and gauge their recovery because historical catches of the ENP population are difficult to separate from catches of other populations in the North Pacific. We collated previously unreported Soviet catches and combined these with known catches to form the most current estimates of North Pacific blue whale catches. We split these conflated catches using recorded acoustic calls from throughout the North Pacific, the knowledge that the ENP population produces a different call than blue whales in the western North Pacific (WNP). The catches were split by estimating spatiotemporal occurrence of blue whales with generalized additive models fitted to acoustic call patterns, which predict the probability a catch belonged to the ENP population based on the proportion of calls of each population recorded by latitude, longitude, and month. When applied to the conflated historical catches, which totaled 9,773, we estimate that ENP blue whale catches totaled 3,411 (95% range 2,593 to 4,114) from 1905-1971, and amounted to 35% (95% range 27% to 42%) of all catches in the North Pacific. Thus most catches in the North Pacific were for WNP blue whales, totaling 6,362 (95% range 5,659 to 7,180). The uncertainty in the acoustic data influence the results substantially more than uncertainty in catch locations and dates, but the results are fairly insensitive to the ecological assumptions made in the analysis. The results of this study provide information for future studies investigating the recovery of these populations and the impact of continuing and future sources of anthropogenic mortality.

  12. North Pacific Origins of Northern Hemisphere Glaciations: The View from the Kuroshio Extension

    NASA Astrophysics Data System (ADS)

    Venti, N. L.; Billups, K.; Herbert, T.

    2013-12-01

    In modern climate, westerly winds augmented by the East Asian winter monsoon (EAWM) cause prodigious ocean-atmosphere heat flux (>100 Wm-2) and provide the primary source of iron to the micronutrient-limited North Pacific. Here we present a suite of high-resolution (2500-year time step) Plio-Pleistocene (3.00-1.76 Ma) proxy records generated in the Kuroshio Current Extension (KCE; Ocean Drilling Program Site 1208). These suggest regularly increased interaction of the EAWM with the North Pacific Ocean prior to obliquity-paced Northern Hemisphere glaciations (NHG). We propose that in the Pleistocene, obliquity-paced EAWM intensification caused NHG by 1) advecting heat and moisture to the atmosphere for snow fall over North America and 2) delivering iron via dust to fertilize the basin, thereby increasing primary productivity and reducing atmospheric CO2 concentrations. To further test this hypothesis, we are exploring appropriate dust proxies and high-resolution CO2 reconstruction. To examine heat transfer, we reconstruct seasonal sea surface temperature (SST) by comparing summer hydrography (salinity and temperature) to a mean annual SST estimate. Planktic foraminifer (warm-water dwelling Globigerinoides ruber) Δδ18O values reflect summer hydrography--KCE warmth. An alkenone-based annual mean SST estimate, on the other hand, incorporates winter cooling from EAWM-enhanced westerlies. With NHG onset at 2.73 Ma, summer SST increases while mean annual SST decreases, suggesting increased heat loss from the subtropical ocean to the mid-latitude atmosphere. On the orbital scale, summer hydrography varies with summer/fall overhead insolation at the 19-kyr precessional band, but not obliquity, a common low-latitude pattern. In contrast, mean annual SST varies primarily at the 41-kyr obliquity period, SST cycles leading high-latitude climate (benthic foraminifer δ18O values). This consistent relationship implies that increased ocean-atmosphere heat transfer in the NW

  13. Towards understanding North Pacific climate variabilty with instrumental and ice core records

    NASA Astrophysics Data System (ADS)

    Kelsey, Eric P.

    Reconstructing climate variability prior to the instrumental era is critical to advance our understanding of the Earth's climate system. Although many paleoclimate records from the North Atlantic basin have been studied, relatively few paleoclimate records have been recovered in the North Pacific leaving a gap in our knowledge concerning North Pacific climate variability. The Eclipse and Mount Logan Prospector-Russell ice cores are favorably located in the St. Elias Mountains, Yukon, Canada to document North Pacific climate variability over the late Holocene. Detailed analysis reveals a consistent relationship of surface air temperature (SAT) anomalies associated with extreme Arctic Oscillation (AO) and Pacific-North America (PNA) index values, and a consistent relationship of North Pacific sea level pressure (SLP) anomalies associated with extreme Mt. Logan annual [Na+] and Eclipse cold season accumulation values. Spatial SAT anomaly patterns are most consistent for AO and PNA index values ≥1.5 and ≤-1.5 during the period 1872-2010. The highest and lowest ˜10% of Eclipse warm and cold season stable isotopes are associated with distinct atmospheric circulation patterns. The most-fractionated isotope values occur with a weaker Aleutian Low, and the least-fractionated isotope values occur with an amplification of the Aleutian Low and northwestern North American ridge. The assumption of stationarity between ice core records and sea-level pressure was tested for the Eclipse cold season accumulation and Mt. Logan annual sodium concentration records for 1872-2001. A stationary relationship was found for ≥95% of years when Mt. Logan sodium concentrations were ≤1.32 microg/L, with positive SLP anomalies in the eastern North Pacific. This high frequency supports the use of low sodium values at Mt. Logan for a reconstruction of SLP prior to 1872. Negative SLP anomalies in the North Pacific occurred for extreme high sodium concentration years and positive SLP

  14. Impacts of Interannual Ocean Circulation Variability on Japanese Eel Larval Migration in the Western North Pacific Ocean

    PubMed Central

    Chang, Yu-Lin; Sheng, Jinyu; Ohashi, Kyoko; Béguer-Pon, Mélanie; Miyazawa, Yasumasa

    2015-01-01

    The Japanese eel larvae hatch near the West Mariana Ridge seamount chain and travel through the North Equatorial Current (NEC), the Kuroshio, and the Subtropical Countercurrent (STCC) region during their shoreward migration toward East Asia. The interannual variability of circulation over the subtropical and tropical regions of the western North Pacific Ocean is affected by the Philippines–Taiwan Oscillation (PTO). This study examines the effect of the PTO on the Japanese eel larval migration routes using a three-dimensional (3D) particle tracking method, including vertical and horizontal swimming behavior. The 3D circulation and hydrography used for particle tracking are from the ocean circulation reanalysis produced by the Japan Coastal Ocean Predictability Experiment 2 (JCOPE2). Our results demonstrate that bifurcation of the NEC and the strength and spatial variation of the Kuroshio affect the distribution and migration of eel larvae. During the positive phase of PTO, more virtual eels (“v-eels”) can enter the Kuroshio to reach the south coast of Japan and more v-eels reach the South China Sea through the Luzon Strait; the stronger and more offshore swing of the Kuroshio in the East China Sea leads to fewer eels entering the East China Sea and the onshore movement of the Kuroshio to the south of Japan brings the eels closer to the Japanese coast. Significant differences in eel migration routes and distributions regulated by ocean circulation in different PTO phases can also affect the otolith increment. The estimated otolith increment suggests that eel age tends to be underestimated after six months of simulation due to the cooler lower layer temperature. Underestimation is more significant in the positive PTO years due to the wide distribution in higher latitudes than in the negative PTO years. PMID:26642318

  15. Impacts of Interannual Ocean Circulation Variability on Japanese Eel Larval Migration in the Western North Pacific Ocean.

    PubMed

    Chang, Yu-Lin; Sheng, Jinyu; Ohashi, Kyoko; Béguer-Pon, Mélanie; Miyazawa, Yasumasa

    2015-01-01

    The Japanese eel larvae hatch near the West Mariana Ridge seamount chain and travel through the North Equatorial Current (NEC), the Kuroshio, and the Subtropical Countercurrent (STCC) region during their shoreward migration toward East Asia. The interannual variability of circulation over the subtropical and tropical regions of the western North Pacific Ocean is affected by the Philippines-Taiwan Oscillation (PTO). This study examines the effect of the PTO on the Japanese eel larval migration routes using a three-dimensional (3D) particle tracking method, including vertical and horizontal swimming behavior. The 3D circulation and hydrography used for particle tracking are from the ocean circulation reanalysis produced by the Japan Coastal Ocean Predictability Experiment 2 (JCOPE2). Our results demonstrate that bifurcation of the NEC and the strength and spatial variation of the Kuroshio affect the distribution and migration of eel larvae. During the positive phase of PTO, more virtual eels ("v-eels") can enter the Kuroshio to reach the south coast of Japan and more v-eels reach the South China Sea through the Luzon Strait; the stronger and more offshore swing of the Kuroshio in the East China Sea leads to fewer eels entering the East China Sea and the onshore movement of the Kuroshio to the south of Japan brings the eels closer to the Japanese coast. Significant differences in eel migration routes and distributions regulated by ocean circulation in different PTO phases can also affect the otolith increment. The estimated otolith increment suggests that eel age tends to be underestimated after six months of simulation due to the cooler lower layer temperature. Underestimation is more significant in the positive PTO years due to the wide distribution in higher latitudes than in the negative PTO years.

  16. Hindcast of 137Cs in the North Pacific Ocean from 1945 to 2013 by eddy-resolving ROMS

    NASA Astrophysics Data System (ADS)

    Tsubono, Takaki; Misumi, Kazuhiro; Tsumune, Daisuke; Aoyama, Michio; Hirose, Katsumi

    2014-05-01

    We conducted the hindcast of 137Cs activity in the North Pacific Ocean from 1945 to 2013, before and after the Fukushima Dai-ichi Nuclear Power Plant (1F NPP) accident. We used the Regional Ocean Model System (ROMS) with high resolution (1/12°-1/4° in horizontal, 45 levels in vertical), of which domain was the North Pacific Ocean. This model employed the CORE normal year forcing data for a driving forcing and the 50 years averaged SODA data for boundary conditions. The reconstructed global fallout due to atmospheric nuclear weapons' tests and Chernobyl accident was employed for atmospheric input flux of 137Cs from 1945 to 2013. After the accident, the atmospheric deposition and direct release of 137Cs from 1F NPP were also employed for input condition. Five ensemble calculations of 137Cs activity were conducted by moving the start period of the input flux for one year. The simulated vertical distributions of 137Cs activity along 165°E represented the overall patterns of the observed 137Cs activity before (in 2002) and after (in 2012) the accident, in particular the high activity core of the 137Cs around North Pacific Subtropical Mode Water and Central Mode Water, indicating that this model can represent the subduction process and formation of the Mode Waters. The simulated 137Cs activity in the surface ranged from 0.75 to 2.Bq m-3 in the north of Kuroshio Extension in 2011 before the accident. The main body of high 137Cs activity water from 1F NPP was transported in the northern part of Kuroshio Extension after the accident. In Sep. 2012, 18 months after the accident, the main body of high 137Cs activity water (≥ 10 Bq m-3) was located at around 40°N, 150°E-160°W. The water over 10 Bq m-3 of 137Cs activity was not detected in surface layer, but in the layer of σθ=25.8-26.2 at two small areas (44°N, 180°W-165°W and 48°N, 160°W-140°W). This model simulation suggests that the main body of high 137Cs activity water from 1F NPP has never reached the

  17. Impact of Fukushima-derived radiocesium in the western North Pacific Ocean about ten months after the Fukushima Dai-ichi nuclear power plant accident.

    PubMed

    Kumamoto, Yuichiro; Aoyama, Michio; Hamajima, Yasunori; Murata, Akihiko; Kawano, Takeshi

    2015-02-01

    We measured vertical distributions of radiocesium ((134)Cs and (137)Cs) at stations along the 149°E meridian in the western North Pacific during winter 2012, about ten months after the Fukushima Dai-ichi Nuclear Power Plant (FNPP1) accident. The Fukushima-derived (134)Cs activity concentration and water-column inventory were largest in the transition region between 35 and 40°N approximately due to the directed discharge of the contaminated water from the FNPP1. The bomb-derived (137)Cs activity concentration just before the FNPP1 accident was derived from the excess (137)Cs activity concentration relative to the (134)Cs activity concentration. The water-column inventory of the bomb-derived (137)Cs was largest in the subtropical region south of 35°N, which implies that the Fukushima-derived (134)Cs will also be transported from the transition region to the subtropical region in the coming decades. Mean values of the water-column inventories decay-corrected for the Fukushima-derived (134)Cs and the bomb-derived (137)Cs were estimated to be 1020 ± 80 and 820 ± 120 Bq m(-2), respectively, suggesting that in winter 2012 the impact of the FNPP1 accident in the western North Pacific Ocean was nearly the same as that of nuclear weapons testing. Relationship between the water-column inventory and the activity concentration in surface water for the radiocesium is essential information for future evaluation of the total amount of Fukushima-derived radiocesium released into the North Pacific Ocean.

  18. Impact of Fukushima-derived radiocesium in the western North Pacific Ocean about ten months after the Fukushima Dai-ichi nuclear power plant accident.

    PubMed

    Kumamoto, Yuichiro; Aoyama, Michio; Hamajima, Yasunori; Murata, Akihiko; Kawano, Takeshi

    2015-02-01

    We measured vertical distributions of radiocesium ((134)Cs and (137)Cs) at stations along the 149°E meridian in the western North Pacific during winter 2012, about ten months after the Fukushima Dai-ichi Nuclear Power Plant (FNPP1) accident. The Fukushima-derived (134)Cs activity concentration and water-column inventory were largest in the transition region between 35 and 40°N approximately due to the directed discharge of the contaminated water from the FNPP1. The bomb-derived (137)Cs activity concentration just before the FNPP1 accident was derived from the excess (137)Cs activity concentration relative to the (134)Cs activity concentration. The water-column inventory of the bomb-derived (137)Cs was largest in the subtropical region south of 35°N, which implies that the Fukushima-derived (134)Cs will also be transported from the transition region to the subtropical region in the coming decades. Mean values of the water-column inventories decay-corrected for the Fukushima-derived (134)Cs and the bomb-derived (137)Cs were estimated to be 1020 ± 80 and 820 ± 120 Bq m(-2), respectively, suggesting that in winter 2012 the impact of the FNPP1 accident in the western North Pacific Ocean was nearly the same as that of nuclear weapons testing. Relationship between the water-column inventory and the activity concentration in surface water for the radiocesium is essential information for future evaluation of the total amount of Fukushima-derived radiocesium released into the North Pacific Ocean. PMID:25461523

  19. Importance of boundary layer mixing for the isotopic composition of surface vapor over the subtropical North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Benetti, Marion; Aloisi, Giovanni; Reverdin, Gilles; Risi, Camille; Sèze, Geneviève

    2015-03-01

    During the summer 2012, we carried out continuous measurements of the isotopic composition (δ) of water vapor over the near-surface subtropical North Atlantic Ocean (STRASSE cruise). In this region of excess evaporation, we investigate the control of evaporation and mixing with a lower troposphere-derived, isotopically depleted air mass on the near-surface δ. We use a simple model to simulate the near-surface δ as the result of a two end-member mixing of the evaporative flux with free tropospheric air. The evaporative flux δ was estimated by the Craig and Gordon equation while the δ of the lower troposphere was taken from the LMDZ-iso global atmospheric circulation model. This simulation considers instantaneous mixing of lower tropospheric air with the evaporated flux and neglects lateral advection. Despite these simplifications, the simulations allow to identify the controls on the near-surface δ. The d-excess variability is largely a consequence of varying kinetic effects during evaporation, even during a convection event when the input of tropospheric vapor was strong. Kinetic effects and mixing processes affect simultaneously the near-surface δ and result in the vapor occupying distinct domains in the δ18O-δD space. The relative humidity-d-excess relationship shows that the closure assumption overestimates the d-excess variability at short time scales (less than a day). We interpret this as due to an effect of the residence time of the near-surface water vapor on the d-excess. Finally, we highlight the importance of reproducing mixing processes in models simulating isotopes over the subtropical North Atlantic Ocean and propose an extension of the closure assumption for use in initial conditions of distillation calculations.

  20. Millennial-scale versus long-term dynamics in the surface and subsurface of the western North Atlantic Subtropical Gyre during Marine Isotope Stage 5

    NASA Astrophysics Data System (ADS)

    Bahr, André; Nürnberg, Dirk; Karas, Cyrus; Grützner, Jens

    2013-12-01

    Subtropical Gyres are an important constituent of the ocean-atmosphere system due to their capacity to store vast amounts of warm and saline waters. Here we decipher the sensitivity of the (sub)surface North Atlantic Subtropical Gyre with respect to orbital and millennial scale climate variability between ~ 140 and 70 ka, Marine Isotope Stage (MIS) 5. Using (isotope) geochemical proxy data from surface and thermocline dwelling foraminifers from Blake Ridge off the west coast of North America (ODP Site 1058) we show that the oceanographic development at subsurface (thermocline) level is substantially different from the surface ocean. Most notably, surface temperatures and salinities peak during the penultimate deglaciation (Termination II) and early MIS 5e, implying that subtropical surface ocean heat and salt accumulation might have resulted from a sluggish northward heat transport. In contrast, maximum thermocline temperatures are reached during late MIS 5e when surface temperatures are already declining. We argue that the subsurface warming originated from intensified Ekman downwelling in the Subtropical Gyre due to enhanced wind stress. During MIS 5a-d a tight interplay of the subtropical upper ocean hydrography to high latitude millennial-scale cold events can be observed. At Blake Ridge, the most pronounced of these high latitude cold events are related to surface warming and salt accumulation in the (sub)surface. Similar to Termination II, heat accumulated in the Subtropical Gyre probably due to a reduced Atlantic Meridional Overturning Circulation. Additionally, a southward shift and intensification of the subtropical wind belts lead to a decrease of on-site precipitation and enhanced evaporation, coupled to intensified gyre circulation. Subsequently, the northward advection of this warm and saline water likely contributed to the fast resumption of the overturning circulation at the end of these high latitude cold events.

  1. Pacific-North America plate motions - New results from very long baseline interferometry

    NASA Technical Reports Server (NTRS)

    Ward, Steven N.

    1990-01-01

    The state of Pacific-North America plate interaction is updated using newest VLBI measurements and newly developed rigid plate tectonic models. Particular attention is given to examining the extent of relative motion between the Pacific plate and the North America plate as measured from their stable interiors, the evidence of Pacific plate deformation off the central California coast, and the distribution of path integrated deformaton east of the San Andreas fault. The information obtained on these questions is discussed in the framework of implications for lithospheric rheology and earthquake hazard.

  2. The probability of tropical cyclone landfalls in Western North Pacific

    NASA Astrophysics Data System (ADS)

    Bonazzi, A.; Bellone, E.; Khare, S.

    2012-04-01

    The Western North Pacific (WNP) is the most active basin in terms of tropical cyclone and typhoon occurrences. The densely populated countries that form the western boundary of WNP basin -- e.g. China, Japan and the Philippines -- are exposed to extreme wind gusts, storm surge and fresh water flooding eventually triggered by Tropical Cyclones (TC) events. Event-based catastrophe models (hereafter cat models) are extensively used by the insurance industry to manage their exposure against low-frequency/high-consequence events such as natural catastrophes. Cat models provide their users with a realistic set of stochastic events that expands the scope of a historical catalogue. Confidence in a cat model ability to extrapolate peril and loss statistics beyond the period covered by observational data requires good agreement between stochastic and historical peril characteristics at shorter return periods. In WNP risk management practitioners are faced with highly uncertain data to base their decisions. Albeit 4 national agencies maintain best track catalogues, data are generally based on satellite imageries with very limited central pressure (CP) and maximum velocity (VMAX) measurements -- regular flight reconnaissance missions stopped in 1987. As a result differences up to 20 knots are found in estimates of VMAX from different agencies as documented in experiment IOP-10 during Typhoon Megi in 2010. In this work we present a comprehensive analysis of CP and VMAX probability distributions at landfall across the WNP basin along a set of 150 gates (100 km coast segments) based on best track catalogues from Japan Meteorological Agency, Joint Typhoon Warning Center, China Meteorological Agency and Hong Meteorological Agency. Landfall distributions are then used to calibrate a random-walk statistical track model. A long simulation of 100,000 years of statistical TC tracks will ultimately constitute the central building block of a basin-wide stochastic catalogue of synthetic TC

  3. Spatial segregation in eastern North Pacific skate assemblages.

    PubMed

    Bizzarro, Joseph J; Broms, Kristin M; Logsdon, Miles G; Ebert, David A; Yoklavich, Mary M; Kuhnz, Linda A; Summers, Adam P

    2014-01-01

    Skates (Rajiformes: Rajoidei) are common mesopredators in marine benthic communities. The spatial associations of individual species and the structure of assemblages are of considerable importance for effective monitoring and management of exploited skate populations. This study investigated the spatial associations of eastern North Pacific (ENP) skates in continental shelf and upper continental slope waters of two regions: central California and the western Gulf of Alaska. Long-term survey data were analyzed using GIS/spatial analysis techniques and regression models to determine distribution (by depth, temperature, and latitude/longitude) and relative abundance of the dominant species in each region. Submersible video data were incorporated for California to facilitate habitat association analysis. We addressed three main questions: 1) Are there regions of differential importance to skates?, 2) Are ENP skate assemblages spatially segregated?, and 3) When skates co-occur, do they differ in size? Skate populations were highly clustered in both regions, on scales of 10s of kilometers; however, high-density regions (i.e., hot spots) were segregated among species. Skate densities and frequencies of occurrence were substantially lower in Alaska as compared to California. Although skates are generally found on soft sediment habitats, Raja rhina exhibited the strongest association with mixed substrates, and R. stellulata catches were greatest on rocky reefs. Size segregation was evident in regions where species overlapped substantially in geographic and depth distribution (e.g., R. rhina and Bathyraja kincaidii off California; B. aleutica and B. interrupta in the Gulf of Alaska). Spatial niche differentiation in skates appears to be more pronounced than previously reported.

  4. Spatial Segregation in Eastern North Pacific Skate Assemblages

    PubMed Central

    Bizzarro, Joseph J.; Broms, Kristin M.; Logsdon, Miles G.; Ebert, David A.; Yoklavich, Mary M.; Kuhnz, Linda A.; Summers, Adam P.

    2014-01-01

    Skates (Rajiformes: Rajoidei) are common mesopredators in marine benthic communities. The spatial associations of individual species and the structure of assemblages are of considerable importance for effective monitoring and management of exploited skate populations. This study investigated the spatial associations of eastern North Pacific (ENP) skates in continental shelf and upper continental slope waters of two regions: central California and the western Gulf of Alaska. Long-term survey data were analyzed using GIS/spatial analysis techniques and regression models to determine distribution (by depth, temperature, and latitude/longitude) and relative abundance of the dominant species in each region. Submersible video data were incorporated for California to facilitate habitat association analysis. We addressed three main questions: 1) Are there regions of differential importance to skates?, 2) Are ENP skate assemblages spatially segregated?, and 3) When skates co-occur, do they differ in size? Skate populations were highly clustered in both regions, on scales of 10s of kilometers; however, high-density regions (i.e., hot spots) were segregated among species. Skate densities and frequencies of occurrence were substantially lower in Alaska as compared to California. Although skates are generally found on soft sediment habitats, Raja rhina exhibited the strongest association with mixed substrates, and R. stellulata catches were greatest on rocky reefs. Size segregation was evident in regions where species overlapped substantially in geographic and depth distribution (e.g., R. rhina and Bathyraja kincaidii off California; B. aleutica and B. interrupta in the Gulf of Alaska). Spatial niche differentiation in skates appears to be more pronounced than previously reported. PMID:25329312

  5. Spatial segregation in eastern North Pacific skate assemblages.

    PubMed

    Bizzarro, Joseph J; Broms, Kristin M; Logsdon, Miles G; Ebert, David A; Yoklavich, Mary M; Kuhnz, Linda A; Summers, Adam P

    2014-01-01

    Skates (Rajiformes: Rajoidei) are common mesopredators in marine benthic communities. The spatial associations of individual species and the structure of assemblages are of considerable importance for effective monitoring and management of exploited skate populations. This study investigated the spatial associations of eastern North Pacific (ENP) skates in continental shelf and upper continental slope waters of two regions: central California and the western Gulf of Alaska. Long-term survey data were analyzed using GIS/spatial analysis techniques and regression models to determine distribution (by depth, temperature, and latitude/longitude) and relative abundance of the dominant species in each region. Submersible video data were incorporated for California to facilitate habitat association analysis. We addressed three main questions: 1) Are there regions of differential importance to skates?, 2) Are ENP skate assemblages spatially segregated?, and 3) When skates co-occur, do they differ in size? Skate populations were highly clustered in both regions, on scales of 10s of kilometers; however, high-density regions (i.e., hot spots) were segregated among species. Skate densities and frequencies of occurrence were substantially lower in Alaska as compared to California. Although skates are generally found on soft sediment habitats, Raja rhina exhibited the strongest association with mixed substrates, and R. stellulata catches were greatest on rocky reefs. Size segregation was evident in regions where species overlapped substantially in geographic and depth distribution (e.g., R. rhina and Bathyraja kincaidii off California; B. aleutica and B. interrupta in the Gulf of Alaska). Spatial niche differentiation in skates appears to be more pronounced than previously reported. PMID:25329312

  6. Ecological context for the North Pacific Landscape Conservation Cooperative

    USGS Publications Warehouse

    Woodward, Andrea; Taylor, Audrey; Weekes, Anne

    2012-01-01

    The North Pacific Landscape Conservation Cooperative (NPLCC) encompasses the temperate coastal rainforest and extends from the coastal mountains to the near-shore from the Kenai Peninsula, Alaska to Bodega Bay, California. The area spans multiple agency, state, and international boundaries over more than 22 degrees of latitude, including a wide range of type and intensity of human land-use activities. Development of NPLCC goals and administrative structures will be facilitated by a shared ecological context for discussing this expansive, diverse, and complex landscape. In support of activities to organize the NPLCC, we provided conceptual models to describe the ecological structure of the NPLCC. Recognizing that the boundaries of LCCs were primarily based on Level 2 of the hierarchical ecoregional classification of Omernik (Comission for Environmental Cooperation 1997), we used nested Level 3 ecoregions to define subregions within the NPLCC. Rather than develop conceptual models for all nine constituent subregions, we opted to consider five groups: Puget-Georgia Basin Lowland and Willamette Valley, Alaska-British Columbia Coast, Alaska-British Columbia Mountains, Klamath-Olympic-Cascade Mountains, and Washington-Oregon-Northern California Coast. At the conclusion of the project, we felt that the close relationship between mountain and coastal areas support combining them to create three major subregions: Alaska-British Columbia coast and mountains, Washington-Oregon-Northern California coast and mountains, and the lowlands of the Georgia Basin and Willamette Valley. The following figures present the Omernik Level 3 ecoregions comprising the NPLCC; how the ecoregions were grouped to create conceptual models; and conceptual models for each group. The five models each consist of a table listing resources, stressors, potential climate change impacts; a landcover map; and a cartoon to summarize the table and evoke the landscape. A final figure summarizes resources

  7. Foods of Buller's shearwaters (Puffinus bulleri) associated with driftnet fisheries in the central North Pacific Ocean

    USGS Publications Warehouse

    Gould, P.; Ostrom, P.; Walker, W.

    1998-01-01

    We examined digestive tract contents and stable nitrogen isotope ratios (??15N) in breast muscles of Buller's shearwaters (Puffinus bulleri) salvaged from squid and largemesh driftnets in the central North Pacific Ocean. The epipelagic Pacific saury (Cololabis saira) was the predominant prey, making up 71% of prey mass in digestive tracts. The remainder of the diet included small numbers of crustaceans, small fishes, and squids. The high degree of specialization in the diet seems to indicate that in the North Pacific, Buller's Shearwaters usually feed at or near the water surface and rarely pursue food under water. Although these birds have been observed feeding on scraps from fishing vessels, our data suggest that offal comprises less than 10% of the diet. Stable nitrogen isotope values provided quantified information on the timing of arrival of migrants into the North Pacific.

  8. Long-term variability of surface nutrient concentrations in the North Pacific

    NASA Astrophysics Data System (ADS)

    Yasunaka, S.; Ono, T.; Nojiri, Y.; Whitney, F. A.; Wada, C.; Murata, A.; Nakaoka, S.; Hosoda, S.

    2016-04-01

    We present the spatial distributions and temporal changes of the long-term variability of surface nutrient concentrations in the North Pacific by using nutrient samples collected by volunteer ships and research vessels from 1961 to 2012. Nutrient samples are optimally interpolated onto 1° × 1° monthly grid boxes. When the Pacific Decadal Oscillation is in its positive phase, nutrient concentrations in the western North Pacific are significantly higher than the climatological means, and those in the eastern North Pacific are significantly lower. When the North Pacific Gyre Oscillation is in its positive phase, nutrient concentrations in the subarctic are significantly higher than the climatological means. The trends of phosphate and silicate averaged over the North Pacific are -0.012 ± 0.005 µmol l-1 decade-1 and -0.38 ± 0.13 µmol l-1 decade-1, whereas the nitrate trend is not significant (0.01 ± 0.13 µmol l-1 decade-1).

  9. Midlatitude atmosphere-ocean interaction during El Nino. Part I. The north Pacific ocean

    SciTech Connect

    Alexander, M.A. )

    1992-09-01

    Atmosphere-ocean modeling experiments are used to investigate the formation of sea surface temperature (SST) anomalies in the North Pacific Ocean during fall and winter of the El Nino year. Experiments in which the NCAR Community Climate Model (CCM) surface fields are used to force a mixed-layer ocean model in the North Pacific (no air-sea feedback) are compared to simulations in which the CCM and North Pacific Ocean model are coupled. Anomalies in the atmosphere and the North Pacific Ocean during El Nino are obtained from the difference between simulations with and without prescribed warm SST anomalies in the tropical Pacific. In both the forced and coupled experiments, the anomaly pattern resembles a composite of the actual SST anomaly field during El Nino: warm SSTs develop along the coast of North America and cold SSTs form in the central Pacific. In the coupled simulations, air-sea interaction results in a 25% to 50% reduction in the magnitude of the SST and mixed-layer depth anomalies, resulting in more realistic SST fields. Coupling also decreases the SST anomaly variance; as a result, the anomaly centers remain statistically significant even though the magnitude of the anomalies is reduced. Three additional sensitivity studies indicate that air-sea feedback and entrainment act to damp SST anomalies while Ekman pumping has a negligible effect on mixed-layer depth and SST anomalies in midatitudes.

  10. 76 FR 58472 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-21

    ... Council's (Council) Pacific Northwest Crab Industry Advisory Committee. SUMMARY: The Pacific Northwest Crab Industry Advisory Committee will meet October 13, 2011 at the Leif Erickson Hall in Ballard, WA... information on these ] fisheries topics: Review total allowable catch (TAC) limits for the 2011/12 crab...

  11. Nutrient regulation of bacterial production and ectoenzyme activities in the subtropical North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Donachie, Stuart P.; Christian, James R.; Karl, David M.

    Interactions between Bacteria and dissolved organic matter (DOM) in the open ocean are poorly understood. While it is likely that particular compounds may disproportionately regulate heterotrophic activity, very little is known about the underlying processes. Through 10 cruises between December 1996 and April 1998 we investigated how heterotrophic (non-pigmented) Bacteria cell production, per cell α- and β-glucosidase and leucine aminopeptidase (LAPase) activities, and 14C-glucose uptake in 0.8 μm filtered seawater (fsw) cultures at Station ALOHA (22°45'N, 158°W) responded to organic and inorganic nutrient additions (glucose, single amino acids, NH 4+, NO 3-). Bacterial cell production did not change significantly in fsw with glucose (1 μM) or single exogenous N sources (1 μM N) compared to that in fsw alone. Furthermore, there was no significant difference in heterotrophic bacterial cell production in fsw amended with organic or inorganic N, nor between that in fsw with organic N and glucose, or inorganic N and glucose. Cell production did increase significantly, however, in fsw with exogenous glucose (0.38 μM) plus 1 μM inorganic N (NH 4+) relative to that in fsw only, in fsw with glucose, and in fsw with 1 μM N as amino acids (His, Tyr, Leu). There was no significant difference between heterotrophic bacterial cell production in fsw with glucose, glucose plus amino acids, and that in fsw alone. Cell-specific LAPase activity increased significantly relative to that in unamended fsw when exogenous glucose plus NH 4+ or NO 3- were provided, but amino acids, glucose, NH 4+ or NO 3- alone had little or no effect. α-Glucosidase activity tended to increase with exogenous His and Tyr additions. Our results suggest that heterotrophic activity at Station ALOHA can be regulated by the abundance of particular compounds, regardless of their total concentrations. It appears that auxotrophy and de novo synthesis of cell protein from glucose may coexist among Bacteria at Station ALOHA, and that regulation of ectoenzyme expression is independent of product availability.

  12. Unicellular cyanobacteria fix N2 in the subtropical North Pacific Ocean.

    PubMed

    Zehr, J P; Waterbury, J B; Turner, P J; Montoya, J P; Omoregie, E; Steward, G F; Hansen, A; Karl, D M

    2001-08-01

    Fixed nitrogen (N) often limits the growth of organisms in terrestrial and aquatic biomes, and N availability has been important in controlling the CO2 balance of modern and ancient oceans. The fixation of atmospheric dinitrogen gas (N2) to ammonia is catalysed by nitrogenase and provides a fixed N for N-limited environments. The filamentous cyanobacterium Trichodesmium has been assumed to be the predominant oceanic N2-fixing microorganism since the discovery of N2 fixation in Trichodesmium in 1961 (ref. 6). Attention has recently focused on oceanic N2 fixation because nitrogen availability is generally limiting in many oceans, and attempts to constrain the global atmosphere-ocean fluxes of CO2 are based on basin-scale N balances. Biogeochemical studies and models have suggested that total N2-fixation rates may be substantially greater than previously believed but cannot be reconciled with observed Trichodesmium abundances. It is curious that there are so few known N2-fixing microorganisms in oligotrophic oceans when it is clearly ecologically advantageous. Here we show that there are unicellular cyanobacteria in the open ocean that are expressing nitrogenase, and are abundant enough to potentially have a significant role in N dynamics. PMID:11493920

  13. Observations of wind-forced deep ocean currents in the North Pacific

    NASA Technical Reports Server (NTRS)

    Koblinsky, C. J.; Niiler, P. P.; Schmitz, W. J., Jr.

    1989-01-01

    The role of the quasi-steady Sverdrup balance in the midlatitude atmospheric response in the North Pacific was investigated by examining 200 instrument-years of moored current measurements in the deep ocean across the breadth of the midlatitude North Pacific. These data provide evidence of a seasonal modulation in the ocean eddy kinetic energy beneath the thermocline at several locations north of 35 deg N, which was often found to be in phase with the local atmospheric forcing function. Results of the measurements indicate that, throughout the midlatitude North Pacific, topography plays a crucial role in the wind forced response; the bottom slope tends to enhance the beta effect in this basin. Topography narrows the available bandwidth for forced barotropic Rossby waves, facilitating a quasi-steady topographic Sverdrup response over most of the basin. However, the enhanced beta effect reduces the magnitude of the ocean's response to wind forcing.

  14. High latitude control on tropical North Pacific thermocline oxygen via deep ocean circulation: implications for atmospheric CO2 and N2O concentrations over TERM1.

    NASA Astrophysics Data System (ADS)

    Jaccard, S. L.; Eric, G. D.; Haug, G. H.; Sigman, D. M.; Francois, R.; Dulski, P.

    2006-12-01

    Low-latitude Pacific Ocean records of past changes in productivity and denitrification have often been ascribed to local processes, including changes in local wind forcing, with some recent hypothesis calling on remote control by thermocline ventilation processes. Here we show that deep thermohaline circulation, a fundamentally high-latitude process, is also linked to the low-latitude thermocline biogeochemistry through its impact on nutrient and dissolved oxygen distributions. We present new, multi-proxy evidence from sediment records from the abyssal subarctic North Pacific, including sedimentary redox-sensitive trace metal distribution, Th-normalized biogenic barium, calcium carbonate, and opal mass accumulation rates, and bulk sedimentary 15N measurements. These proxies show that the abyss was significantly depleted in oxygen, and low 13C, all consistent with high DIC concentrations. Meanwhile, above a deep chemical divide, the overlying waters were relatively well-oxygenated and nutrient-poor. At the mid-point of the deglaciation, the glacial deep water mass dissipated upwards in the water column, releasing deeply-sequestered CO2 to the atmosphere and shifting nutrients into the thermocline. The flux of regenerated nutrients to the sunlit surface ocean associated with this breakdown of the deep water mass enhanced primary productivity throughout the subarctic Pacific, while records from lower latitudes of the North Pacific show a parallel boom in export production. The accelerated flux of organic matter from the surface contributed towards an intensification of the thermocline oxygen minimum zone, accelerating denitrification in the Eastern (sub)tropical North Pacific and the production of nitrous oxide. These observations, taken together with our evidence for changes in the deep North Pacific, suggest that the flux of nutrients from the deep North Pacific into the upper water column increased at the end of the ice age. This release may have occurred via the

  15. Effect of biomass burning over the western North Pacific Rim: wintertime maxima of anhydrosugars in ambient aerosols from Okinawa

    NASA Astrophysics Data System (ADS)

    Zhu, C.; Kawamura, K.

    2014-10-01

    Biomass burning (BB) largely modifies the chemical compositions of atmospheric aerosols on the globe. We collected aerosol samples (TSP) at Cape Hedo, subtropical Okinawa Island from October 2009 to February 2012 to study anhydrosugars as BB tracers. Levoglucosan was detected as the dominant anhydrosugar followed by its isomers, mannosan and galactosan. We found a clear seasonal trend of levoglucosan and mannosan with winter maxima and summer minima. Positive correlation was found between levoglucosan and nss-K+ (r = 0.38, p < 0.001); the latter is another BB tracer. The analyses of air mass trajectories and fire spots demonstrated that the seasonal variations of anhydrsosugsars are caused by a long-range transport of BB emissions from the Asian continent. We found winter maxima of anhydrosugars, which may be associated with open burning and domestic heating and cooking in north and northeast China, Mongolia and Russia and with the enhanced westerly. The monthly averaged levoglucosan/mannosan ratios were lower (2.1-4.8) in May-June and higher (13.3-13.9) in November-December. The lower values may be associated with softwood burning in north China, Korea and southwest Japan whereas the higher values are probably caused by agriculture waste burning of maize straw in the North China Plain. Anhydrosugars comprised 0.22% of water-soluble organic carbon (WSOC) and 0.13% of organic carbon (OC). The highest values to WSOC (0.37%) and OC (0.25%) were found in winter, again indicating an important BB contribution to Okinawa aerosols in winter. This study provides useful information to better understand the effect of East Asian biomass burning on the air quality in the western North Pacific Rim.

  16. Dissolved phosphorus pools and alkaline phosphatase activity in the euphotic zone of the Western north pacific ocean.

    PubMed

    Suzumura, Masahiro; Hashihama, Fuminori; Yamada, Namiha; Kinouchi, Shinko

    2012-01-01

    We measured pools of dissolved phosphorus (P), including dissolved inorganic P (DIP), dissolved organic P (DOP) and alkaline phosphatase (AP)-hydrolyzable labile DOP (L-DOP), and kinetic parameters of AP activity (APA) in the euphotic zone in the western North Pacific Ocean. Samples were collected from one coastal station in Sagami Bay, Japan, and three offshore stations between the North Pacific subtropical gyre (NPSG) and the Kuroshio region. Although DIP concentrations in the euphotic zone at all stations were equally low, around the nominal method detection limit of 20 nmol L(-1), chlorophyll a (Chl a) concentrations were one order of magnitude greater at the coastal station. DOP was the dominant P pool, comprising 62-92% of total dissolved P at and above the Chl a maximum layer (CML). L-DOP represented 22-39% of the total DOP at the offshore stations, whereas it accounted for a much higher proportion (about 85%) in the coastal surface layers. Significant correlations between maximum potential AP hydrolysis rates and DIP concentrations or bacterial cell abundance in the offshore euphotic zone suggest that major APA in the oligotrophic surface ocean is from bacterial activity and regulated largely by DIP availability. Although the range of maximum potential APA was comparable among the environmental conditions, the in situ hydrolysis rate of L-DOP in the coastal station was 10 times those in the offshore stations. L-DOP turnover time at the CML ranged from 4.5 days at the coastal station to 84.4 days in the NPSG. The ratio of the APA half-saturation constant to the ambient L-DOP concentration decreased markedly from the NPSG to the coastal station. There were substantial differences in the rate and efficiency of DOP remineralization and its contribution as the potential P source between the low-phosphate/high-biomass coastal ecosystem and the low-phosphate/low biomass oligotrophic ocean. PMID:22457661

  17. Organic matter transformations in the upper mesopelagic zone of the North Pacific: Chemical composition and linkages to microbial community structure

    NASA Astrophysics Data System (ADS)

    Kaiser, Karl; Benner, Ronald

    2012-01-01

    Transformation processes in the euphotic and mesopelagic zones are of crucial importance to the biological pump and global elemental cycles. In this study, elemental stoichiometries and chemical compositions of particulate and dissolved organic matter (DOM) were investigated in the euphotic and upper mesopelagic zones of the North Pacific Subtropical Gyre. The distributions of bacterial biomarkers (D-amino acids, muramic acid) and major biochemicals (amino acids, neutral sugars, amino sugars) indicated a direct link between microbial community structure and the biochemical composition of organic matter. Bacteria were major sources of organic C, N, and P in the upper mesopelagic zone. Heterotrophic bacterial transformations were important in the formation of biorefractory organic matter that is retained in the ocean on timescales of decades to millennia. Net removal rates for dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and major biochemicals were calculated for the upper mesopelagic zone (110-300 m). Dissolved hydrolyzable amino acids, neutral sugars, and amino sugars comprised 5-18% of DOC and 4-5% of DON removed in the upper mesopelagic zone, indicating these biochemicals were important components of semilabile DOM. Net removal rates of neutral sugars were 3-10 times higher than net removal rates of amino acids and amino sugars. This suggested that neutral sugars were the most reactive component among the three classes of biochemicals. Depth-integrated net DOC removal rates indicated that DOC comprised 19-31% of total carbon export flux in the North Pacific gyre and supplied 27-93% of bacterial carbon demand in the upper mesopelagic zone.

  18. Dissolved phosphorus pools and alkaline phosphatase activity in the euphotic zone of the Western north pacific ocean.

    PubMed

    Suzumura, Masahiro; Hashihama, Fuminori; Yamada, Namiha; Kinouchi, Shinko

    2012-01-01

    We measured pools of dissolved phosphorus (P), including dissolved inorganic P (DIP), dissolved organic P (DOP) and alkaline phosphatase (AP)-hydrolyzable labile DOP (L-DOP), and kinetic parameters of AP activity (APA) in the euphotic zone in the western North Pacific Ocean. Samples were collected from one coastal station in Sagami Bay, Japan, and three offshore stations between the North Pacific subtropical gyre (NPSG) and the Kuroshio region. Although DIP concentrations in the euphotic zone at all stations were equally low, around the nominal method detection limit of 20 nmol L(-1), chlorophyll a (Chl a) concentrations were one order of magnitude greater at the coastal station. DOP was the dominant P pool, comprising 62-92% of total dissolved P at and above the Chl a maximum layer (CML). L-DOP represented 22-39% of the total DOP at the offshore stations, whereas it accounted for a much higher proportion (about 85%) in the coastal surface layers. Significant correlations between maximum potential AP hydrolysis rates and DIP concentrations or bacterial cell abundance in the offshore euphotic zone suggest that major APA in the oligotrophic surface ocean is from bacterial activity and regulated largely by DIP availability. Although the range of maximum potential APA was comparable among the environmental conditions, the in situ hydrolysis rate of L-DOP in the coastal station was 10 times those in the offshore stations. L-DOP turnover time at the CML ranged from 4.5 days at the coastal station to 84.4 days in the NPSG. The ratio of the APA half-saturation constant to the ambient L-DOP concentration decreased markedly from the NPSG to the coastal station. There were substantial differences in the rate and efficiency of DOP remineralization and its contribution as the potential P source between the low-phosphate/high-biomass coastal ecosystem and the low-phosphate/low biomass oligotrophic ocean.

  19. Decadal changes in multi-scale water vapor transport and atmospheric river associated with the Pacific Decadal Oscillation and the North Pacific Gyre Oscillation

    NASA Astrophysics Data System (ADS)

    Ren, X.

    2015-12-01

    This study investigates the features of atmospheric circulation and moisture transport associated with two modes of decadal variability in the North Pacific: the Pacific Decadal Oscillation (PDO) and the North Pacific Gyre Oscillation (NPGO), with emphasis on the multi-scale water vapor transport and atmospheric river (AR) over the North Pacific region. During the positive phase of PDO, the geopotential height anomaly at 500 hPa exhibits a Pacific-North American like pattern. During the positive phase of NPGO, the geopotential height anomaly at 500 hPa features a dipole pattern with a negative anomaly north of 40°N and a positive anomaly south of 40°N over the North Pacific. Associated with the positive PDO phase, the ocean-to-land moisture transport is enhanced between 25°N and 35°N and reduced over the Northeast Pacific for the time-mean integrated vapor transport (IVT). The synoptic poleward transport is suppressed north of 40°N and enhanced south of 40°N. In the positive NPGO phase, the zonal moisture transport is intensified south of 20°N and between 40°N and 50°N for the time-mean IVT and weakened over the west coast of North America for the low-frequency IVT. The synoptic poleward transport is suppressed south of 30°N. The eastern part of the North Pacific AR belt moves southward during positive PDO as the entire North Pacific AR belt shifts slightly northward during positive NPGO. An investigation on AR anomalies during a period over which the PDO and NPGO coexist demonstrates that the AR frequency over the North American western coastal regions is significantly influenced by the conjunction of the PDO and NPGO modes.

  20. Temperature and zooplankton size structure: climate control and basin-scale comparison in the North Pacific

    PubMed Central

    Chiba, Sanae; Batten, Sonia D; Yoshiki, Tomoko; Sasaki, Yuka; Sasaoka, Kosei; Sugisaki, Hiroya; Ichikawa, Tadafumi

    2015-01-01

    The global distribution of zooplankton community structure is known to follow latitudinal temperature gradients: larger species in cooler, higher latitudinal regions. However, interspecific relationships between temperature and size in zooplankton communities have not been fully examined in terms of temporal variation. To re-examine the relationship on a temporal scale and the effects of climate control thereon, we investigated the variation in copepod size structure in the eastern and western subarctic North Pacific in 2000–2011. This report presents the first basin-scale comparison of zooplankton community changes in the North Pacific based on a fully standardized data set obtained from the Continuous Plankton Recorder (CPR) survey. We found an increase in copepod community size (CCS) after 2006–2007 in the both regions because of the increased dominance of large cold-water species. Sea surface temperature varied in an east–west dipole manner, showing the typical Pacific Decadal Oscillation pattern: cooling in the east and warming in the west after 2006–2007. The observed positive correlation between CCS and sea surface temperature in the western North Pacific was inconsistent with the conventional interspecific temperature–size relationship. We explained this discrepancy by the geographical shift of the upper boundary of the thermal niche, the 9°C isotherm, of large cold-water species. In the eastern North Pacific, the boundary stretched northeast, to cover a large part of the sampling area after 2006–2007. In contrast, in the western North Pacific, the isotherm location hardly changed and the sampling area remained within its thermal niche throughout the study period, despite the warming that occurred. Our study suggests that while a climate-induced basin-scale cool–warm cycle can alter copepod community size and might subsequently impact the functions of the marine ecosystem in the North Pacific, the interspecific temperature–size relationship

  1. Temperature and zooplankton size structure: climate control and basin-scale comparison in the North Pacific.

    PubMed

    Chiba, Sanae; Batten, Sonia D; Yoshiki, Tomoko; Sasaki, Yuka; Sasaoka, Kosei; Sugisaki, Hiroya; Ichikawa, Tadafumi

    2015-02-01

    The global distribution of zooplankton community structure is known to follow latitudinal temperature gradients: larger species in cooler, higher latitudinal regions. However, interspecific relationships between temperature and size in zooplankton communities have not been fully examined in terms of temporal variation. To re-examine the relationship on a temporal scale and the effects of climate control thereon, we investigated the variation in copepod size structure in the eastern and western subarctic North Pacific in 2000-2011. This report presents the first basin-scale comparison of zooplankton community changes in the North Pacific based on a fully standardized data set obtained from the Continuous Plankton Recorder (CPR) survey. We found an increase in copepod community size (CCS) after 2006-2007 in the both regions because of the increased dominance of large cold-water species. Sea surface temperature varied in an east-west dipole manner, showing the typical Pacific Decadal Oscillation pattern: cooling in the east and warming in the west after 2006-2007. The observed positive correlation between CCS and sea surface temperature in the western North Pacific was inconsistent with the conventional interspecific temperature-size relationship. We explained this discrepancy by the geographical shift of the upper boundary of the thermal niche, the 9°C isotherm, of large cold-water species. In the eastern North Pacific, the boundary stretched northeast, to cover a large part of the sampling area after 2006-2007. In contrast, in the western North Pacific, the isotherm location hardly changed and the sampling area remained within its thermal niche throughout the study period, despite the warming that occurred. Our study suggests that while a climate-induced basin-scale cool-warm cycle can alter copepod community size and might subsequently impact the functions of the marine ecosystem in the North Pacific, the interspecific temperature-size relationship is not

  2. Temporal variation of 137Cs water column inventory in the North Pacific since the 1960s.

    PubMed

    Aoyama, M; Hirose, K

    2003-01-01

    The temporal variation of water column inventories of 137Cs in the North Pacific since the 1960s was examined based on the analysis of the 137Cs profiles in HAM database. 137Cs in seawater in the North Pacific have originated mainly from global fallout from atmospheric nuclear weapons tests, which occurred in the early 1960s. In the 1960s, both the meridional distribution of 137Cs inventory in the North Pacific and that of fallout on land stations showed mid-latitude maximum. The region with higher deposition at land stations, however, was more northern than the latitudes where the 137Cs inventory in the North Pacific showed a maximum. The difference of the latitude where maximum 137Cs deposition/inventory was observed reflects the difference of the geographical distribution of the precipitation amount in the Pacific and Atlantic Oceans followed by the different warm current systems in each ocean. A good positive relation between 137Cs inventory and annual precipitation amount was discovered in the ocean stations at the middle latitude in the North Pacific. The horizontal distribution of 137Cs inventories at the middle latitudes in the North Pacific is characterized as west-high and east-low in the early 1960s, which was basically controlled by the distribution of annual precipitation amount. Eastward advection, then, modified it to be less difference in 1966-1967 after the highest deposition periods in 1963-1965. In the 1970s and 1980s, increases of the 137Cs inventory at the lower latitude of 10-20 deg. N are found. Surface and subsurface southward transports are considered as the source of this increasing 137Cs inventory.

  3. Temperature and zooplankton size structure: climate control and basin-scale comparison in the North Pacific.

    PubMed

    Chiba, Sanae; Batten, Sonia D; Yoshiki, Tomoko; Sasaki, Yuka; Sasaoka, Kosei; Sugisaki, Hiroya; Ichikawa, Tadafumi

    2015-02-01

    The global distribution of zooplankton community structure is known to follow latitudinal temperature gradients: larger species in cooler, higher latitudinal regions. However, interspecific relationships between temperature and size in zooplankton communities have not been fully examined in terms of temporal variation. To re-examine the relationship on a temporal scale and the effects of climate control thereon, we investigated the variation in copepod size structure in the eastern and western subarctic North Pacific in 2000-2011. This report presents the first basin-scale comparison of zooplankton community changes in the North Pacific based on a fully standardized data set obtained from the Continuous Plankton Recorder (CPR) survey. We found an increase in copepod community size (CCS) after 2006-2007 in the both regions because of the increased dominance of large cold-water species. Sea surface temperature varied in an east-west dipole manner, showing the typical Pacific Decadal Oscillation pattern: cooling in the east and warming in the west after 2006-2007. The observed positive correlation between CCS and sea surface temperature in the western North Pacific was inconsistent with the conventional interspecific temperature-size relationship. We explained this discrepancy by the geographical shift of the upper boundary of the thermal niche, the 9°C isotherm, of large cold-water species. In the eastern North Pacific, the boundary stretched northeast, to cover a large part of the sampling area after 2006-2007. In contrast, in the western North Pacific, the isotherm location hardly changed and the sampling area remained within its thermal niche throughout the study period, despite the warming that occurred. Our study suggests that while a climate-induced basin-scale cool-warm cycle can alter copepod community size and might subsequently impact the functions of the marine ecosystem in the North Pacific, the interspecific temperature-size relationship is not

  4. Dynamics and Thermodynamics of the North Pacific Ocean

    NASA Technical Reports Server (NTRS)

    Kelly, Kathryn A.

    2002-01-01

    Observations from the TOPEX/POSEIDON (T/P) radar altimeter, along with other observations and meteorological products, were used to examine the relationship between ocean dynamics and thermodynamics in the Pacific Ocean.

  5. 76 FR 71321 - North Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-17

    ... (CIE) Terms of Reference). 2. Pacific Cod Jig Fishery Management: Report on Board of Fisheries action... Committees and tasking. 10. Other Business The SSC agenda will include the following issues: 1....

  6. 76 FR 60806 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-30

    ... (also known as the ``CSP'') for the charter and commercial Pacific halibut sectors and (2) developing... maximum size, which is currently proposed under the management tier of the CSP that is associated with...

  7. A Mid-Holocene Shift and Millennial-Scale Variations in Mesopelagic North Pacific Ventilation

    NASA Astrophysics Data System (ADS)

    Lembke-Jene, Lester; Tiedemann, Ralf; Nuernberg, Dirk

    2014-05-01

    The modern subarctic North Pacific Ocean is one major region of the world ocean, where a halocline prevents the existence of a deep meridional overturning cell, and the formation of new deepwater masses in the North Pacific today. Only mid-depth water layers are ventilated by North Pacific Intermediate Water (NPIW) that receives its comparably high oxygen content from water masses formed by brine rejection in the Okhotsk Sea. In this presentation, we report on multi-proxy sediment records from such intermediate water depths in the Okhotsk Sea. High primary productivity, sea ice dynamics and patterns, highly variable hydrographic conditions, and fluvial terrigenous sediment supply closely interact in these regions and precondition the formation and ventilation pattern of intermediate waters. Founded on a coherent, AMS 14C-derived regional stratigraphic framework, high sedimentation rates in select cores (20-200 cm/kyr enable us to decipher rapid changes in North Pacific Intermediate Water dynamics on interdecadal to millennial time scales over the Holocene. We provide the first high-resolution stable isotope datasets from epibenthic foraminifera combined with productivity proxies to reconstruct changes in paleo-hydrography and ventilation patterns. We maintain that the current ventilation pattern of the mid-depth North Pacific has only been prevalent for the last c. 2,000 years before present. We further provide evidence for a mid-Holocene shift in ventilation patterns, changing the natural baseline NPIW oxygen characteristics around 4,000 to 6,000 years before present.

  8. Processes and mechanisms for the model SST biases in the North Atlantic and North Pacific: A link with the Atlantic meridional overturning circulation

    NASA Astrophysics Data System (ADS)

    Zhang, Liping; Zhao, Chuanhu

    2015-06-01

    Almost all of CMIP5 climate models show cold SST biases in the extratropical North Atlantic (ENA) and tropical North Atlantic (TNA) as well as in the North Pacific which are commonly linked with the weak simulated Atlantic meridional overturning circulation (AMOC). A weak AMOC and its associated reduced northward oceanic heat transport are associated with a cooling of the ENA Ocean, whereas the TNA cooling is attributable to both weak AMOC and surface heat flux. The cold biases in the ENA and TNA have remote impacts on the SST bias in the North Pacific. Here we use coupled ocean-atmosphere model experiments to show the mechanisms and pathways by which the ENA and TNA affect the North Pacific. The model simulations demonstrate that the cooling SST bias in the North Pacific is largely due to the remote effect of the cooling SST bias in the ENA, while the remote impact of the TNA cooling SST bias is of secondary importance. The ENA cooling bias triggers the circumglobal teleconnection via the Northern Hemisphere annular mode, producing a strengthening of the Aleutian low, an enhancement of the southward Ekman and Oyashio cold advection, and thus a cooling SST in the North Pacific. In contrast, the TNA cooling produces a surface high extending to the eastern tropical North Pacific, inducing the northeasterly wind anomalies north, northerly cross-equatorial wind anomalies, and northwesterly wind anomalies south of the equator. This C-shape wind anomaly pattern generates an SST warming in the tropical southeastern Pacific, which eventually leads to an SST warming in the tropical central and western Pacific by the wind-evaporation-SST feedback. The tropical Pacific warming in turn leads to an SST cooling in the North Pacific by the Pacific North American teleconnection pattern.

  9. Overview of surface ozone variability in East Asia-North Pacific region during IGAC/APARE (1994--1996).

    PubMed

    Lam, K S; Wang, T J; Wang, T; Tang, J; Kajii, Y; Liu, C M; Shim, S G

    2004-01-01

    Surface ozone (O3) was measured at Oki Island (Japan), Cheju Island (South Korea), Lanyu Island (Taiwan Province, China), Cape D'Aguilar (Hong Kong SAR) and Lin'an, Longfenshan, Waliguan (China mainland) during January 1994--December 1996 as a component of IGAC/APARE (International Global Atmospheric Chemistry/East Asia-North Pacific Regional Experiment). This paper gave a joint discussion on the observational results at these stations over the study region. Investigations showed that the average of surface O3 mixing ratios at the seven sites are 47.9+/-15.8, 48.1+/-17.9, 30.2+/-16.4, 31.6+/-17.5, 36.3+/-17.5, 34.8+/-11.5 and 48.2+/-9.5 ppbv, respectively. Significant diurnal variations of surface O3 have been observed at Oki, Cheju, D'Aguilar, Lin'an and Longfenshan. Their annual averaged diurnal differences range from 8 to 23 ppbv and differ in each season. Surface O3 at Lanyu and Waliguan do not show strong diurnal variability. Seasonal cycles of surface O3 showed difference at the temperate and the subtropical remote sites. Oki has a summer minimum-spring maximum, while Lanyu has a summer minimum-autumn maximum. The suburban sites at D'Aguilar and Lin'an report high-level O3 in autumn and low level O3 in summer. Surface O3 remains-high in autumn and low in winter at the rural site Longfenshan. For the global background station Waliguan, surface O3 exhibits a broad spring-summer maximum and autumn-winter minimum. The backward air trajectories to these sites have shown different pathways of long-range transport of air pollution from East Asia Continent to North Pacific Ocean. Surface O3 was found to be strongly and positively correlated with CO at Oki and Lanyu, especially in spring and autumn, reflecting the substantial photochemical buildup of O3 on a regional scale. It is believed that the regional sources of pollution in East Asia have enhanced the average surface O3 concentrations in the background atmosphere of North Pacific. PMID:15495964

  10. Century-scale variability of Coralline Algal Calcification Rates in the North Pacific and North Atlantic

    NASA Astrophysics Data System (ADS)

    Halfar, J.; Chan, P.; Adey, W.; Hetzinger, S.; Williams, B.; Steneck, R.; Lebednik, P.

    2012-04-01

    Ocean acidification may inhibit calcification pathways of marine plants and animals. Recently, it has been suggested that aragonitic tropical corals and other marine calcifiers already exhibit declining calcification rates. Greater oceanic CO2 uptake at mid-to-high latitudes may result in greater inhibition of calcium carbonate secretion in subarctic organisms than in those at lower latitudes. Such inhibition may be particularly evident in the metabolically expensive high Mg-calcite skeletons of the shallow-water, habitat-forming coralline algae. It has been shown that biogenic high Mg-calcites exceed the solubility of aragonite at approximately 12 mol% MgCO3. Here we present the first century-scale records of calcification rates in the coralline alga Clathromorphum sp. from the North Pacific/Bering Sea region and the subarctic NW Atlantic. Clathromorphum forms annual growth increments in its massive skeleton and is known to have a lifespan of up to several centuries. The seasonal MgCO3 range in Clathromorphum from our subarctic collection sites fluctuates between 10-15 mol%. Century-long time series of calcification rates - the product of skeletal density and linear extension - were generated at submonthly resolution using Micro Computer Tomography. Results indicate that coralline algal calcification rates display multidecadal cycles that covary with regional climate indices such as the Pacific Decadal Oscillation. Unlike studies of other marine calcifiers, this study has not detected a significant decline in calcification rates during the past decades. This is likely attributable to Clathromorphum calcification being metabolically driven, with the organism maintaining significant physiological control over both placement and dissolution of carbonate. Most carbonate in Clathromorphum cells is deposited along an inner wall embedded in an organic matrix of very small, radially-placed high magnesium calcite crystals.

  11. North Pacific seasonality and the glaciation of North America 2.7 million years ago

    NASA Astrophysics Data System (ADS)

    Haug, G. H.; Ganopolski, A.; Sigman, D. M.; Rosell-Mele, A.; Swann, G. E.; Tiedemann, R.; Jaccard, S. L.; Bollmann, J.; Maslin, M. A.; Leng, M. J.; Eglinton, G.

    2006-12-01

    To initiate and sustain the large Northern Hemisphere ice sheets of the Plio-Pleistocene ice ages, in particular the large Laurentide ice masses on North America, two requirements are broadly recognized. First, the more polar continental areas must be sufficiently cold for precipitation to fall as snow rather than rain and for snow and ice to survive the warm summer melting season. Second, adequate moisture must be introduced to high northern latitudes to promote the accumulation of glacial ice. In attempts to explain the initiation of major Northern Hemisphere Glaciation 2.7 Myr ago, much attention has been given to the temperature requirements of continental glaciation. The time interval between 4.5 and 3.1 Myr was dominated by a pronounced long-term minimum in the amplitude of the 41 kyr cycle in the obliquity of Earth's rotation which would have failed to produce particularly cold northern hemisphere summers, the key requirement posited by Milankovitch for the onset of northern hemisphere glaciation. During this time interval, there may have been several aborted shifts toward glaciation, for example between 4.1 - 3.9 Myr and 3.5 - 3.3 Myr. During the late Pliocene and early Pleistocene, a high amplitude in the obliquity cycle resulted in periods of low tilt angle, which, in turn, would have yielded periods with cold summers in the Northern Hemisphere. Thus, it has been suggested that the progressive increase in the amplitude of the obliquity cycle tipped the scale between 3.1 - 2.5 Myr, allowing for long-term expansion of Northern Hemisphere ice. In short, our long-held view of the temperature requirement of glaciation is largely consistent with the timing of the onset of Northern Hemisphere Glaciation. However, the onset of Northern Hemisphere glaciation has proven to be inconsistent with ideas regarding the water vapor requirement. The subarctic Pacific represents a major source of water vapor to boreal North America yet has largely been overlooked in efforts

  12. Paleoclimate. Synchronization of North Pacific and Greenland climates preceded abrupt deglacial warming.

    PubMed

    Praetorius, Summer K; Mix, Alan C

    2014-07-25

    Some proposed mechanisms for transmission of major climate change events between the North Pacific and North Atlantic predict opposing patterns of variations; others suggest synchronization. Resolving this conflict has implications for regulation of poleward heat transport and global climate change. New multidecadal-resolution foraminiferal oxygen isotope records from the Gulf of Alaska (GOA) reveal sudden shifts between intervals of synchroneity and asynchroneity with the North Greenland Ice Core Project (NGRIP) δ(18)O record over the past 18,000 years. Synchronization of these regions occurred 15,500 to 11,000 years ago, just prior to and throughout the most abrupt climate transitions of the last 20,000 years, suggesting that dynamic coupling of North Pacific and North Atlantic climates may lead to critical transitions in Earth's climate system. PMID:25061208

  13. Deformation across the western United States: A local estimate of Pacific-North America transform deformation

    NASA Technical Reports Server (NTRS)

    Humphreys, Eugene D.; Weldon, Ray J., II

    1994-01-01

    We obtain a locally based estimate of Pacific-North America relative motion and an uncertainly in this estimate by integrating deformation rate along three different paths leading west across southwestern North America from east of the Rio Grande Rift to near the continental escarpment. Data are primarily Quatenary geologic slip rates estimates, and resulting deformation determinations therefore are 'instantaneous' in a geologic sense but 'long term' with respect to earthquake cycles. We deduce a rate of motion of the Pacific plane relative to North America that is 48 +/- 2 mm/yr, a rate indistinguishable from that predicted by the global kinematics models RM2 and NUVEL-1; however, we obtain an orientation that is 5-9 deg counterclockwise of these models. A more westerly motion of the Pacific plate, with respect to North America, is calculated from all three paths. The relatively westerly motion of the Pacific plate is accomodated by deformation in the North American continent that includes slip on relatively counterclockwise-oriented strike-slip faults (including the San Andreas fault), whic is especially relevant in and south of the Transverse Ranges, and a margin-normal component of net extension across the continent, which is especially relevant north of the Transverse Ranges. Deformation of the SW United States occurs in regionally coherent domains within the style of deformation is approximately uniform.

  14. Origin of millennial-scale climate signals in the subtropical North Atlantic

    NASA Astrophysics Data System (ADS)

    Billups, Katharina; Scheinwald, Andre

    2014-06-01

    We present a high-resolution planktonic foraminiferal stable isotope record (Globigerinoides ruber) spanning marine oxygen isotope stages (MISs) 6 through 8 in the northwestern subtropical Atlantic Ocean (Ocean Drilling Program Leg 172 Site 1059). The record fills a gap to produce an about 1.3 Myr long continuous time series of high-frequency (> ~1/12 kyr) surface ocean hydrography, the first of this kind. We test the hypothesis that the suborbital climate signals (i.e., half and quarter precession cycles) are linked to precession forcing in tropical latitudes. Semiprecession cycles present between 0 and 320 ka are of the right periodicity to relate to the dominant precession forcing (23 kyr). These cycles are evident as double peaks within the given precession framework, and there is good match in the amplitude modulation of the filter output and the δ18O time series. Quarter precession cycles dominate the suborbital spectra between 320 ka and 1.3 Ma. Periodicities are close to those expected from the harmonics of the dominant precession peaks in the δ18O record, but present in the time series only intermittently, and their amplitude modulation does not match that of the primary precession period. Thus, only the half precession cycles evidence a response to low-latitude insolation such as that introduced by insolation maxima at the equinoxes or solstices during the course of a precession cycle. Additionally, we find well-defined, rapid (~1.5-2 kyr) variations across the first of the interglacial maxima of MIS 7 adding to evidence of non-ice sheet-related forcing factors in driving climate instabilities.

  15. Dependency of the North Pacific winter storm tracks on the zonal distribution of MJO convection

    NASA Astrophysics Data System (ADS)

    Lee, Yun-Young; Lim, Gyu-Ho

    2012-07-01

    We investigate the effects of the tropical Madden Julian Oscillation (MJO) convection on the zonal location and intensity of storm activity during the boreal cool season (Nov. 1 to Feb. 28, 120 days) over the Pacific Ocean. As tropical convection shifts eastward from the eastern Indian Ocean to the western North Pacific, MJO-induced local Hadley circulation leads to an eastward displacement of extratropical Rossby Wave Source (RWS). Consequently, this influence leads to an eastward shift of the peak area of the storm track. The storm track is strongest with the MJO convection over the eastern Indian Ocean (phase 3), and it experiences the suppression when MJO convection is located over the Maritime continents (phase 4), and it increases again when the MJO propagates to the western Pacific (phase 5), after which it weakens again (phase 6). The intensity of the storm track, particularly over the western North Pacific (120°E-180°), is determined by the integrated effects of three factors: the midlatitude convective forcing (MCF), the jet stream, and RWS. These factors are associated with the locations of MJO convections. It is estimated that MJO-induced suppression accounts for only 2.5% of the total observed midwinter suppression (MWS). However, the pattern generated by the MJO is remarkably similar to the observed meridional displacement of North Pacific storm track associated with sub-seasonal variation. We conclude that the spatial distribution of MJO affects the variation of the Pacific storm track, but is not a cause of the MWS.

  16. Retrieval the statistical-dynamical model of western Pacific subtropical high ridge line index and key members of Asian summer monsoon system

    NASA Astrophysics Data System (ADS)

    Hong, Mei; Zhang, Ren; Wang, Dong; Chen, Xi; Shi, Jian; Singh, Vijay

    2014-12-01

    The western Pacific subtropical high (WPSH) is closely correlated with the East Asian climate. To date, the underlying mechanisms and sustaining factors have not been positively elucidated. Based on the concept of dynamical system model reconstruction, this paper presents a nonlinear statistical-dynamical model of the subtropical high ridge line (SHRL) in concurrence with four summer monsoon factors. SHRL variations from 1990 to 2011 are subdivided into three categories, while parameter differences relating to three differing models are examined. Dynamical characteristics of SHRL are analyzed and an aberrance mechanism subsequently developed. Modeling suggests that different parameters may lead to significant variance pertaining to monsoon variables corresponding with numerous WPSH activities. Dynamical system bifurcation and mutation indicates that the South China Sea monsoon trough is a significant factor with respect to the occurrence and maintenance of the 'double-ridge' phenomenon. Moreover, the occurrence of the Mascarene cold high is predicted to cause an abnormal northward location of WPSH, resulting in the “empty plum” phenomenon.

  17. Dependence of the relationship between the tropical cyclone track and western Pacific subtropical high intensity on initial storm size: A numerical investigation

    NASA Astrophysics Data System (ADS)

    Sun, Yuan; Zhong, Zhong; Yi, Lan; Li, Tim; Chen, Ming; Wan, Hongchao; Wang, Yuxing; Zhong, Kai

    2015-11-01

    A suite of numerical experiments were conducted to investigate the sensitivity of the tropical cyclone (TC) motion—western Pacific subtropical high (WPSH) intensity relationship to initial storm size. Two TC cases, Songda (2004) and Megi (2010), were studied. It was found that with the increase of initial storm size, the main body of the WPSH tends to withdraw eastward and the TC tends to turn northward earlier. The involved physical mechanism was investigated. Rather than the change of the beta effect due to storm size change, it is the change of the geopotential height in the TC outer region that is critical for the different TC tracks between the sensitivity experiments. Due to increase of the initial storm size, the inflow mass flux entering the TC region increases, leading to a significant decrease in 500 hPa geopotential height in the TC outer region after 2-3 day integration. As a result, the simulated intensity of the WPSH over its fringe close to the TC decreases notably when the WPSH edge is within the TC outer region. Such a decrease leads to a break of WPSH. Subsequently, the TC turns northward toward the break of the subtropical high. This further weakens the intensity of the WPSH over the region close to the TC. The result helps us better understand the relationship between the TC track and WPSH intensity. It also indicates that a proper representation of initial storm size is important for realistic prediction of TC track and the change of the WPSH.

  18. Contribution of Tropical Cyclones to the North Pacific Climatological Rainfall as Observed from Satellites

    NASA Technical Reports Server (NTRS)

    Rodgers, Edward B.; Adler, Robert F.; Pierce, Harold F.

    1997-01-01

    Tropical cyclone monthly rainfall amounts are estimated from passive microwave satellite observations for an eleven year period. These satellite-derived rainfall amounts are used to assess the impact of tropical cyclone rainfall in altering the geographical, seasonal, and inter-annual distribution of the North Pacific Ocean total rainfall during June-November when tropical cyclones are most important. To estimate these tropical cyclone rainfall amounts, mean monthly rain rates are derived from passive microwave satellite observations within 444 km radius of the center of those North Pacific tropical cyclones that reached storm stage and greater. These rain rate observations are converted to monthly rainfall amounts and then compared to those for non-tropical cyclone systems. The main results of this study indicate that: 1) tropical cyclones contribute 7% of the rainfall to the entire domain of the North Pacific during the tropical cyclone season and 12%, 3%, and 4% when the study area is limited to, respectively, the western, central, and eastern third of the ocean; 2) the maxima in tropical cyclone rainfall are poleward (5 deg to 10 deg latitude depending on longitude) of the maxima in non-tropical cyclone rainfall; 3) tropical cyclones contribute a maximum of 30% northeast of the Philippine Islands and 40% of the lower Baja California coast; 4) in the western North Pacific, the tropical cyclone rainfall lags the total rainfall by approximately two months and shows seasonal latitudinal variation following the ITCZ; and 5) in general, tropical cyclone rainfall is enhanced during the El Nino years by warm SSTs in the eastern North Pacific and by the monsoon trough in the western and central North Pacific.

  19. On the Influence of North Pacific Sea Surface Temperature on the Arctic Winter Climate

    NASA Technical Reports Server (NTRS)

    Hurwitz, Margaret M.; Newman, P. A.; Garfinkel, C. I.

    2012-01-01

    Differences between two ensembles of Goddard Earth Observing System Chemistry-Climate Model simulations isolate the impact of North Pacific sea surface temperatures (SSTs) on the Arctic winter climate. One ensemble of extended winter season forecasts is forced by unusually high SSTs in the North Pacific, while in the second ensemble SSTs in the North Pacific are unusually low. High Low differences are consistent with a weakened Western Pacific atmospheric teleconnection pattern, and in particular, a weakening of the Aleutian low. This relative change in tropospheric circulation inhibits planetary wave propagation into the stratosphere, in turn reducing polar stratospheric temperature in mid- and late winter. The number of winters with sudden stratospheric warmings is approximately tripled in the Low ensemble as compared with the High ensemble. Enhanced North Pacific SSTs, and thus a more stable and persistent Arctic vortex, lead to a relative decrease in lower stratospheric ozone in late winter, affecting the April clear-sky UV index at Northern Hemisphere mid-latitudes.

  20. Dynamical response of the North Pacific Ocean to the tropical variability and its decadal modulation

    NASA Astrophysics Data System (ADS)

    Nonaka, M.; Taguchi, B.; Schneider, N.

    2015-12-01

    While teleconnections from the tropical Pacific to the North Pacific sea surface temperature are well known, the dynamical response of the North Pacific Ocean to the tropical atmosphere-ocean variability is not well investigated. Based on observed and reanalysis data, we investigate this link through a correlation analysis using the indices of Nino3, Nino3.4, and El Nino Modoki Index (EMI). The simultaneous correlation maps of the wind-stress curl indicate that the signal associated with EMI in the eastern North Pacific is stronger than the counterparts with Nino3 and Nino3.4. Responding to these signals in wind-stress curl, sea surface height (SSH) anomalies develop following EMI, but almost no SSH responses are found to Nino3 and Nino3.4. As El Nino Modoki lasts for a longer period than canonical El Nino, the stronger wind-stress curl signal to EMI drives the ocean more persistently, and induces substantial SSH signals. The induced SSH signals propagate westward to the western boundary region around 35N, affecting variability in the Kuroshio Extension, which might further exert feedback on the atmosphere aloft. The teleconnection from EMI to the North Pacific, however, was not found before the 1990s, indicating its clear decadal modulation.

  1. Aeolian contamination of Se and Ag in the North Pacific from Asian fossil fuel combustion.

    PubMed

    Ranville, Mara A; Cutter, Gregory A; Buck, Clifton S; Landing, William M; Cutter, Lynda S; Resing, Joseph A; Flegal, A Russell

    2010-03-01

    Energy production from fossil fuels, and in particular the burning of coal in China, creates atmospheric contamination that is transported across the remote North Pacific with prevailing westerly winds. In recent years this pollution from within Asia has increased dramatically, as a consequence of vigorous economic growth and corresponding energy consumption. During the fourth Intergovernmental Oceanographic Commission baseline contaminant survey in the western Pacific Ocean from May to June, 2002, surface waters and aerosol samples were measured to investigate whether atmospheric deposition of trace elements to the surface North Pacific was altering trace element biogeochemical cycling. Results show a presumably anthropogenic enrichment of Ag and of Se, which is a known tracer of coal combustion, in the North Pacific atmosphere and surface waters. Additionally, a strong correlation was seen between dissolved Ag and Se concentrations in surface waters. This suggests that Ag should now also be considered a geochemical tracer for coal combustion, and provides further evidence that Ag exhibits a disturbed biogeochemical cycle as the result of atmospheric deposition to the North Pacific.

  2. Changing central Pacific El Niños reduce stability of North American salmon survival rates

    PubMed Central

    Kilduff, D. Patrick; Di Lorenzo, Emanuele; Botsford, Louis W.; Teo, Steven L. H.

    2015-01-01

    Pacific salmon are a dominant component of the northeast Pacific ecosystem. Their status is of concern because salmon abundance is highly variable—including protected stocks, a recently closed fishery, and actively managed fisheries that provide substantial ecosystem services. Variable ocean conditions, such as the Pacific Decadal Oscillation (PDO), have influenced these fisheries, while diminished diversity of freshwater habitats have increased variability via the portfolio effect. We address the question of how recent changes in ocean conditions will affect populations of two salmon species. Since the 1980s, El Niño Southern Oscillation (ENSO) events have been more frequently associated with central tropical Pacific warming (CPW) rather than the canonical eastern Pacific warming ENSO (EPW). CPW is linked to the North Pacific Gyre Oscillation (NPGO), whereas EPW is linked to the PDO, different indicators of northeast Pacific Ocean ecosystem productivity. Here we show that both coho and Chinook salmon survival rates along western North America indicate that the NPGO, rather than the PDO, explains salmon survival since the 1980s. The observed increase in NPGO variance in recent decades was accompanied by an increase in coherence of local survival rates of these two species, increasing salmon variability via the portfolio effect. Such increases in coherence among salmon stocks are usually attributed to controllable freshwater influences such as hatcheries and habitat degradation, but the unknown mechanism underlying the ocean climate effect identified here is not directly subject to management actions. PMID:26240365

  3. Changing central Pacific El Niños reduce stability of North American salmon survival rates.

    PubMed

    Kilduff, D Patrick; Di Lorenzo, Emanuele; Botsford, Louis W; Teo, Steven L H

    2015-09-01

    Pacific salmon are a dominant component of the northeast Pacific ecosystem. Their status is of concern because salmon abundance is highly variable--including protected stocks, a recently closed fishery, and actively managed fisheries that provide substantial ecosystem services. Variable ocean conditions, such as the Pacific Decadal Oscillation (PDO), have influenced these fisheries, while diminished diversity of freshwater habitats have increased variability via the portfolio effect. We address the question of how recent changes in ocean conditions will affect populations of two salmon species. Since the 1980s, El Niño Southern Oscillation (ENSO) events have been more frequently associated with central tropical Pacific warming (CPW) rather than the canonical eastern Pacific warming ENSO (EPW). CPW is linked to the North Pacific Gyre Oscillation (NPGO), whereas EPW is linked to the PDO, different indicators of northeast Pacific Ocean ecosystem productivity. Here we show that both coho and Chinook salmon survival rates along western North America indicate that the NPGO, rather than the PDO, explains salmon survival since the 1980s. The observed increase in NPGO variance in recent decades was accompanied by an increase in coherence of local survival rates of these two species, increasing salmon variability via the portfolio effect. Such increases in coherence among salmon stocks are usually attributed to controllable freshwater influences such as hatcheries and habitat degradation, but the unknown mechanism underlying the ocean climate effect identified here is not directly subject to management actions. PMID:26240365

  4. Progress in the study on the formation of the summertime subtropical anticyclone

    NASA Astrophysics Data System (ADS)

    Liu, Yimin; Wu, Guoxiong

    2004-06-01

    The studies in China on the formation of the summertime subtropical anticyclone on the climate timescale are reviewed. New insights in resent studies are introduced. It is stressed that either in the free atmosphere or in the planetary boundary, the descending arm of the Hadley cell cannot be considered as a mechanism for the formation of the subtropical anticyclone. Then the theories of thermal adaptation of the atmosphere to external thermal forcing and the potential vorticity forcing are developed to understand the formation of the subtropical anticyclone in the three-dimensional domain. Numerical experiments are designed to verify these theories. Results show that in the boreal summer, the formation of the strong South Asian High in the upper troposphere and the subtropical anticyclone over the western Pacific in the middle and lower troposphere is, to a great extent, due to the convective latent heating associated with the Asian monsoon, but affected by orography and the surface sensible heating over the continents. On the other hand, the formation of the subtropical anticyclone at the surface over the northern Pacific and in the upper troposphere over North America is mainly due to the strong surface sensible heating over North America, but affected by radiation cooling over the eastern North Pacific. Moreover, in the real atmosphere such individual thermal forcing is well organized. By considering the different diabatic heating in synthesis, a quadruple heating pattern is found over each subtropical continent and its adjacent oceans in summer. A distinct circulation pattern accompanies this heating pattern. The global summer subtropical heating and circulation may be viewed as “mosaics” of such quadruplet heating and circulation patterns respectively. At last, some important issues for further research in understanding and predicting the variations of the subtropical anticyclone are raised.

  5. Abundance and Distribution of Dimethylsulfoniopropionate Degradation Genes and the Corresponding Bacterial Community Structure at Dimethyl Sulfide Hot Spots in the Tropical and Subtropical Pacific Ocean

    PubMed Central

    Suzuki, Shotaro; Omori, Yuko; Wong, Shu-Kuan; Ijichi, Minoru; Kaneko, Ryo; Kameyama, Sohiko; Tanimoto, Hiroshi; Hamasaki, Koji

    2015-01-01

    Dimethylsulfoniopropionate (DMSP) is mainly produced by marine phytoplankton but is released into the microbial food web and degraded by marine bacteria to dimethyl sulfide (DMS) and other products. To reveal the abundance and distribution of bacterial DMSP degradation genes and the corresponding bacterial communities in relation to DMS and DMSP concentrations in seawater, we collected surface seawater samples from DMS hot spot sites during a cruise across the Pacific Ocean. We analyzed the genes encoding DMSP lyase (dddP) and DMSP demethylase (dmdA), which are responsible for the transformation of DMSP to DMS and DMSP assimilation, respectively. The averaged abundance (±standard deviation) of these DMSP degradation genes relative to that of the 16S rRNA genes was 33% ± 12%. The abundances of these genes showed large spatial variations. dddP genes showed more variation in abundances than dmdA genes. Multidimensional analysis based on the abundances of DMSP degradation genes and environmental factors revealed that the distribution pattern of these genes was influenced by chlorophyll a concentrations and temperatures. dddP genes, dmdA subclade C/2 genes, and dmdA subclade D genes exhibited significant correlations with the marine Roseobacter clade, SAR11 subgroup Ib, and SAR11 subgroup Ia, respectively. SAR11 subgroups Ia and Ib, which possessed dmdA genes, were suggested to be the main potential DMSP consumers. The Roseobacter clade members possessing dddP genes in oligotrophic subtropical regions were possible DMS producers. These results suggest that DMSP degradation genes are abundant and widely distributed in the surface seawater and that the marine bacteria possessing these genes influence the degradation of DMSP and regulate the emissions of DMS in subtropical gyres of the Pacific Ocean. PMID:25862229

  6. Abundance and distribution of dimethylsulfoniopropionate degradation genes and the corresponding bacterial community structure at dimethyl sulfide hot spots in the tropical and subtropical pacific ocean.

    PubMed

    Cui, Yingshun; Suzuki, Shotaro; Omori, Yuko; Wong, Shu-Kuan; Ijichi, Minoru; Kaneko, Ryo; Kameyama, Sohiko; Tanimoto, Hiroshi; Hamasaki, Koji

    2015-06-15

    Dimethylsulfoniopropionate (DMSP) is mainly produced by marine phytoplankton but is released into the microbial food web and degraded by marine bacteria to dimethyl sulfide (DMS) and other products. To reveal the abundance and distribution of bacterial DMSP degradation genes and the corresponding bacterial communities in relation to DMS and DMSP concentrations in seawater, we collected surface seawater samples from DMS hot spot sites during a cruise across the Pacific Ocean. We analyzed the genes encoding DMSP lyase (dddP) and DMSP demethylase (dmdA), which are responsible for the transformation of DMSP to DMS and DMSP assimilation, respectively. The averaged abundance (±standard deviation) of these DMSP degradation genes relative to that of the 16S rRNA genes was 33% ± 12%. The abundances of these genes showed large spatial variations. dddP genes showed more variation in abundances than dmdA genes. Multidimensional analysis based on the abundances of DMSP degradation genes and environmental factors revealed that the distribution pattern of these genes was influenced by chlorophyll a concentrations and temperatures. dddP genes, dmdA subclade C/2 genes, and dmdA subclade D genes exhibited significant correlations with the marine Roseobacter clade, SAR11 subgroup Ib, and SAR11 subgroup Ia, respectively. SAR11 subgroups Ia and Ib, which possessed dmdA genes, were suggested to be the main potential DMSP consumers. The Roseobacter clade members possessing dddP genes in oligotrophic subtropical regions were possible DMS producers. These results suggest that DMSP degradation genes are abundant and widely distributed in the surface seawater and that the marine bacteria possessing these genes influence the degradation of DMSP and regulate the emissions of DMS in subtropical gyres of the Pacific Ocean.

  7. Invasive range expansion by the Humboldt squid, Dosidicus gigas, in the eastern North Pacific

    PubMed Central

    Zeidberg, Louis D.; Robison, Bruce H.

    2007-01-01

    A unique 16-year time series of deep video surveys in Monterey Bay reveals that the Humboldt squid, Dosidicus gigas, has substantially expanded its perennial geographic range in the eastern North Pacific by invading the waters off central California. This sustained range expansion coincides with changes in climate-linked oceanographic conditions and a reduction in competing top predators. It is also coincident with a decline in the abundance of Pacific hake, the most important commercial groundfish species off western North America. Recognizing the interactive effects of multiple changes in the environment is an issue of growing concern in ocean conservation and sustainability research. PMID:17646649

  8. North Pacific Mesoscale Coupled Air-Ocean Simulations Compared with Observations

    SciTech Connect

    Cerovecki, Ivana; McClean, Julie; Koracin, Darko

    2014-11-14

    The overall objective of this study was to improve the representation of regional ocean circulation in the North Pacific by using high resolution atmospheric forcing that accurately represents mesoscale processes in ocean-atmosphere regional (North Pacific) model configuration. The goal was to assess the importance of accurate representation of mesoscale processes in the atmosphere and the ocean on large scale circulation. This is an important question, as mesoscale processes in the atmosphere which are resolved by the high resolution mesoscale atmospheric models such as Weather Research and Forecasting (WRF), are absent in commonly used atmospheric forcing such as CORE forcing, employed in e.g. the Community Climate System Model (CCSM).

  9. Deglacial pulses of deep-ocean silicate into the subtropical North Atlantic Ocean.

    PubMed

    Meckler, A N; Sigman, D M; Gibson, K A; François, R; Martínez-García, A; Jaccard, S L; Röhl, U; Peterson, L C; Tiedemann, R; Haug, G H

    2013-03-28

    Growing evidence suggests that the low atmospheric CO2 concentration of the ice ages resulted from enhanced storage of CO2 in the ocean interior, largely as a result of changes in the Southern Ocean. Early in the most recent deglaciation, a reduction in North Atlantic overturning circulation seems to have driven CO2 release from the Southern Ocean, but the mechanism connecting the North Atlantic and the Southern Ocean remains unclear. Biogenic opal export in the low-latitude ocean relies on silicate from the underlying thermocline, the concentration of which is affected by the circulation of the ocean interior. Here we report a record of biogenic opal export from a coastal upwelling system off the coast of northwest Africa that shows pronounced opal maxima during each glacial termination over the past 550,000 years. These opal peaks are consistent with a strong deglacial reduction in the formation of silicate-poor glacial North Atlantic intermediate water (GNAIW). The loss of GNAIW allowed mixing with underlying silicate-rich deep water to increase the silicate supply to the surface ocean. An increase in westerly-wind-driven upwelling in the Southern Ocean in response to the North Atlantic change has been proposed to drive the deglacial rise in atmospheric CO2 (refs 3, 4). However, such a circulation change would have accelerated the formation of Antarctic intermediate water and sub-Antarctic mode water, which today have as little silicate as North Atlantic Deep Water and would have thus maintained low silicate concentrations in the Atlantic thermocline. The deglacial opal maxima reported here suggest an alternative mechanism for the deglacial CO2 release. Just as the reduction in GNAIW led to upward silicate transport, it should also have allowed the downward mixing of warm, low-density surface water to reach into the deep ocean. The resulting decrease in the density of the deep Atlantic relative to the Southern Ocean surface promoted Antarctic overturning

  10. Changes in the relationship in the SST variability between the tropical Pacific and the North Pacific across 1998/99 regime shift

    NASA Astrophysics Data System (ADS)

    Jo, H. S.; Yeh, S. W.; Lee, S. K.

    2014-12-01

    This study examines why the relationship in the sea surface temperature (SST) variability between the tropical Pacific and the North Pacific during the boreal winter (Dec.-Jan.) has been changed across the 1998/99 regime shift. While, the SST variability in the central-to-eastern tropical Pacific is highly negatively correlated with that in the central-to-eastern North Pacific after the 1998/99 regime shift, it is not before the 1998/99 regime shift. It is found that the anomalous Aleutian low pressure in response to the tropical SST forcing becomes stronger and its center is shifted to the south and to the west after the 1998/99 to regime shift, which plays a key role to tighten the relationship in the tropical Pacific-North Pacific SST variability. Such a modulation of Aleutian low pressure is mainly due to the location of tropical heating, which is shifted to the west around the dateline in the tropical Pacific across the 1998/99 regime shift. Simple atmospheric model experiments also support this hypothesis that the shift of tropical heating to the west is responsible for strengthening the relationship in the tropical Pacific-North Pacific SST variability via the modulation of atmospheric teleconnections.

  11. Rates of dissolved organic carbon (DOC) production and bacterial activity in the eastern North Atlantic Subtropical Gyre during summer

    NASA Astrophysics Data System (ADS)

    Teira, E.; Pazó, M. J.; Quevedo, M.; Fuentes, M. V.; Niell, F. X.; Fernández, E.

    2003-04-01

    Rates of particulate organic carbon production, dissolved organic carbon production (DOC) and bacterial production were measured at 8 stations located in the eastern North Atlantic Subtropical Gyre during August 1998. Euphotic-depth-integrated particulate organic carbon (POC) production rate was on average 27 mg C m-2 h-1. The corresponding averaged integrated DOC production rate was 5 mg C m-2 h-1, i.e., about 20 % of total primary production. No statistically significant relationship was found between the rates of DOC and POC production, suggesting that other processes besides phytoplankton exudation, such as cell lysis or protist grazing, could substantially contribute to the release of DOC. Euphotic-depth-integrated bacterial biomass and production were, on average, 214 mg C m-2 and 1.4 mg C m-2 h-1, respectively. The lack of correlation between the rates of DOC release and bacterial activity, and a bacterial carbon demand (BCD, calculated by using an estimated bacterial growth efficiency ranging from 11 to 18%) in excess of DOC production suggest the existence of additional organic carbon sources (both allochthonous and/or autochthonous reservoirs), apart from in situ phytoplankton-derived DOC production, for the maintenance of bacterial activity in this region during summer.

  12. Annual and decadal variability in the western subtropical North Atlantic: signal characteristics and sampling methodologies

    NASA Astrophysics Data System (ADS)

    Molinari, Robert L.

    2004-07-01

    Upper ocean (above 750 m) temperature structure of the northwestern subtropical Atlantic, including the Gulf Stream and a recirculation gyre south of the Stream, is characterized using primarily bathythermograph (BT) data collected between 1950 and 2003. Geostrophic calculations, using mean temperature-salinity relationships to compute dynamic height, are used to estimate velocities and transports. The mean annual Gulf Stream transport at 72° W relative to 750 m, 36.1 Sv, is approximately equal to the sum of the transport of the Florida Current, 32.0 Sv, and a shallow recirculation gyre described by Wang and Koblinsky [Journal of Physical Oceanography 26 (1996) 2462-2479], 5.5 Sv. The annual cycle of geostrophic transport relative to 750 m at 72° W is in phase with both an earlier published annual cycle of transport relative to 2000 m derived from hydrographic observations and the annual cycle of Florida Current transport measured indirectly by a submarine cable (i.e., maximum transports are observed in the summer and minimum in the fall, early winter). However, simple Sverdrup dynamics are inadequate to explain these cycles as maximum Sverdrup transports extend from winter to summer, while observed transports are minimum (maximum) in fall/winter (summer). The annual cycles derived from the BT data of the size of the shallow southern recirculation gyre, Gulf Stream position and upper layer transport (relative to 300 m) are in phase (maximum size, northern position and transport in fall) and consistent with the WK results derived from altimetry. However, the shallower annual cycles are out of phase with the deeper signals (i.e., maximum for the former (latter) are observed in fall (summer)). Decadal signals after 1965 in Gulf Stream position, geostrophic transport relative to 450 m, and the size of a recirculation gyre south of the Stream are approximately in phase as observed for the annual signal. This gyre and the shallow WK gyre exhibit the same horizontal

  13. Heterotrophic bacterial production and extracellular enzymatic activity in sinking particulate matter in the western North Pacific Ocean.

    PubMed

    Yamada, Namiha; Fukuda, Hideki; Ogawa, Hiroshi; Saito, Hiroaki; Suzumura, Masahiro

    2012-01-01

    Heterotrophic activities on sinking particulate matter (SPM) play an important role in SPM fluxes in the ocean. To demonstrate regional differences in heterotrophic activities on SPM, we measured heterotrophic bacterial production (HBP) in seawater (HBP(SW)) and SPM (HBP(SPM)) as well as potential extracellular enzyme activity (EEA) in SPM on a transect along 155°E in the western North Pacific Ocean in the subarctic (44°N), the Kuroshio Extension area (35°N), and the subtropical gyre (20°N). Depth-integrated HBP(SW) from the surface to 500 m was comparable between the locations, whereas HBP(SPM) at 44°N was substantially lower than at the other sites. We found the highest particulate organic carbon (POC) export flux and export efficiency to bathypelagic depths, and the lowest water temperatures, at 44°N. We found significant correlations between leucine aminopeptidase (LAPase) activity, β-glucosidase (BGase) activity, POC flux and particulate organic nitrogen flux. LAPase activity was two orders of magnitude higher than BGase activity, with a BGase:LAPase activity ratio of 0.027. There were no significant correlations between HBP and EEA in SPM except for lipase, and lipase activity was significantly correlated with temperature. We propose that hydrographic conditions are an important factor controlling heterotrophic bacterial activity and export efficiency of organic carbon to the deep ocean, as are the sources and abundance of SPM produced in the euphotic zone via primary production. PMID:23109933

  14. Decreasing trend of tropical cyclone genesis frequency in July-August over the western North Pacific in the last 20 years

    NASA Astrophysics Data System (ADS)

    Choi, Ki-Seon; Kim, Hae-Dong; Kang, Sung-Dae; Shim, Chang-Sup

    2016-07-01

    This study analyzed the frequency of tropical cyclones (TCs) that occurred in each month of July to September, which is when most TCs occur during a year, in the western North Pacific for the last 20 years. Since the mid-1990s, the TC genesis frequency has tended to decrease during July to August but to increase during September. Therefore, the time series of the TC genesis frequency during July to August was analyzed. The average TC genesis frequency during July to August was 10TCs. Until 2006, a greater number of years had a TC genesis frequency more than 10TCs; however, from 2006, a greater number of years had a TC genesis frequency less than 10TCs. To determine why the TC genesis frequency showed this change in the mid-2000s, the difference between the average of July and August 2007 to 2014 (0714) and that of July and August 1995 to 2006 (9506) was analyzed. With regard to the TC genesis frequency, TCs occurred largely in the eastern sea of the Philippines during 0714 and in the distant eastern sea of the Philippines during 9506. With regard to the TC passage frequency, TCs came ashore at the southeastern area of China via the South China Sea from the Philippines during 0714 and tended to go north toward Korea and Japan through the East China Sea from the distant eastern sea of the Philippines during 9506. The cause of the differences in TC tracks between the two periods was verified through an analysis of the 850- and 500-hPa streamlines. During 0714, anomalous anticyclonic circulations were strengthened in most areas of the western North Pacific. Therefore, the TC genesis frequency during 0714 was lower than that during 9506 in the tropical and subtropical western North Pacific; in particular, in this area, anomalous easterlies were strengthened, which caused TCs to go toward the southeastern area of China.

  15. Transient Tracer Evidence for an Internal Flow Path of Denmark Strait Overflow Water from the Subpolar to the Subtropical Western North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Smethie, W. M.; Smith, J. N.; Curry, R. G.

    2012-12-01

    The Deep Western Boundary Current is a well known conduit for transporting dense water formed in the northern North Atlantic Ocean southward to the subtropical and tropical North Atlantic Ocean. However, hydrographic and tracer observations suggest that there is also an interior pathway transporting these dense waters to the subtropical North Atlantic. Climatological potential vorticity fields indicate interior flow in the Denmark Strait Overflow Water (DSOW) density horizon from the Grand Banks to the Bermuda Rise. Observations of CFCs and I-129 along a line of stations occupied to the southeast of Bermuda in 2010 as part of the DynAMITE project, reveal a core of elevated tracer concentrations in DSOW to the southeast of Bermuda, which supports an interior flow path. Comparison of hydrographic properties and tracer concentrations along this line and Line W, which crosses the DWBC to the northwest of Bermuda, indicate somewhat longer transport times from the subpolar region to the subtropics for the interior pathway and greater dilution of the tracer concentration by mixing.

  16. Marine biogenic source of atmospheric organic nitrogen in the subtropical North Atlantic.

    PubMed

    Altieri, Katye E; Fawcett, Sarah E; Peters, Andrew J; Sigman, Daniel M; Hastings, Meredith G

    2016-01-26

    Global models estimate that the anthropogenic component of atmospheric nitrogen (N) deposition to the ocean accounts for up to a third of the ocean's external N supply and 10% of anthropogenic CO2 uptake. However, there are few observational constraints from the marine atmospheric environment to validate these findings. Due to the paucity of atmospheric organic N data, the largest uncertainties related to atmospheric N deposition are the sources and cycling of organic N, which is 20-80% of total N deposition. We studied the concentration and chemical composition of rainwater and aerosol organic N collected on the island of Bermuda in the western North Atlantic Ocean over 18 mo. Here, we show that the water-soluble organic N concentration ([WSON]) in marine aerosol is strongly correlated with surface ocean primary productivity and wind speed, suggesting a marine biogenic source for aerosol WSON. The chemical composition of high-[WSON] aerosols also indicates a primary marine source. We find that the WSON in marine rain is compositionally different from that in concurrently collected aerosols, suggesting that in-cloud scavenging (as opposed to below-cloud "washout") is the main contributor to rain WSON. We conclude that anthropogenic activity is not a significant source of organic N to the marine atmosphere over the North Atlantic, despite downwind transport from large pollution sources in North America. This, in conjunction with previous work on ammonium and nitrate, leads to the conclusion that only 27% of total N deposition to the global ocean is anthropogenic, in contrast to the 80% estimated previously. PMID:26739561

  17. Marine biogenic source of atmospheric organic nitrogen in the subtropical North Atlantic

    PubMed Central

    Altieri, Katye E.; Fawcett, Sarah E.; Peters, Andrew J.; Sigman, Daniel M.; Hastings, Meredith G.

    2016-01-01

    Global models estimate that the anthropogenic component of atmospheric nitrogen (N) deposition to the ocean accounts for up to a third of the ocean’s external N supply and 10% of anthropogenic CO2 uptake. However, there are few observational constraints from the marine atmospheric environment to validate these findings. Due to the paucity of atmospheric organic N data, the largest uncertainties related to atmospheric N deposition are the sources and cycling of organic N, which is 20–80% of total N deposition. We studied the concentration and chemical composition of rainwater and aerosol organic N collected on the island of Bermuda in the western North Atlantic Ocean over 18 mo. Here, we show that the water-soluble organic N concentration ([WSON]) in marine aerosol is strongly correlated with surface ocean primary productivity and wind speed, suggesting a marine biogenic source for aerosol WSON. The chemical composition of high-[WSON] aerosols also indicates a primary marine source. We find that the WSON in marine rain is compositionally different from that in concurrently collected aerosols, suggesting that in-cloud scavenging (as opposed to below-cloud “washout”) is the main contributor to rain WSON. We conclude that anthropogenic activity is not a significant source of organic N to the marine atmosphere over the North Atlantic, despite downwind transport from large pollution sources in North America. This, in conjunction with previous work on ammonium and nitrate, leads to the conclusion that only 27% of total N deposition to the global ocean is anthropogenic, in contrast to the 80% estimated previously. PMID:26739561

  18. Interdecadal changes in the co-variability of North Pacific Oscillation and Pacific Meridional Mode and their impact on the tropical Pacific climate variability

    NASA Astrophysics Data System (ADS)

    Shin, So-Jung; An, Soon-Il

    2016-04-01

    North Pacific Oscillation (NPO) and Pacific Meridional Mode (PMM) are known as the representatives of extratropical stochastic forcings to influence the tropical Pacific climate, especially El Nino-Southern Oscillation (ENSO), through a wind-evaporation-SST (WES) feedback mechanism (a.k.a. 'seasonal footprinting'). NPO and PMM are obviously independent phenomena, but sometimes they occur together. Here, we explore the concurrence of NPO and PMM for the period of 1872 - 2012, and found that the concurrence of NPO and PMM is related to the eastward migration of Aleutian Low. A conditional composite analysis showed that only when NPO and PMM occurred together, the El Nino-like SST anomalies were significantly induced in the following winter. Furthermore, the co-variability between NPO and PMM shows the noticeable interdecadal variations, which is somehow related to the change in the mean North Pacific upper-level jet stream. This is because the mean jet stream affects the location and intensity of Aleutian Low. We further analyzed the various coupled model simulations, and found that the model simulations provide consistent results to the observation.

  19. An interdecadal change in the relationship between the western North Pacific Ocean and the East Asian summer monsoon

    NASA Astrophysics Data System (ADS)

    Yu, Peilong; Zhang, Lifeng; Zhong, Quanjia

    2016-09-01

    This study reveals that the relationship between the western North Pacific Ocean (WNPO; 0-55°N, 100-165°E) and the East Asian summer monsoon (EASM) experiences a well-defined interdecadal change in the late 1980s and early 1990s. The EASM-related WNPO sea surface temperature anomaly (SSTA) pattern changes from the dipole pattern [WNPO dipole (WNPOD)] that develops over the period between 1968 and 1987 (P1) to a tripole pattern [WNPO tripole (WNPOT)] between 1991 and 2010 (P2). The positive (negative) phase of the WNPOD is characterized by warm (cold) SSTAs in the Japan Sea and Kuroshio-Oyashio Extension region, and cold (warm) SSTAs in the subtropical WNPO, whereas the positive (negative) phase of the WNPOT shows warming (cooling) in the Kuroshio Extension region (KER), and cooling (warming) in the south of Kamchatka Peninsula (SKP) and Philippine Sea (PS). During P1 (P2), the WNPOD (WNPOT) can be regarded as the first (second) leading mode of summer WNPO SST variability, and its positive phase is associated with a weakened WNPO subtropical high and thereby the deficient summer rainfall in the Yangtze River valley, together with a strong EASM, and vice versa. The change in the WNPO-EASM relationship may be caused by interdecadal changes in the relationship of the equatorial central Pacific (ECP) with the WNPO and EASM, and an increase in summer KER SST variability. During P2, because the ECP warming-induced cyclonic anomalies move northwestwards and intensify, summertime ECP warming is able to generate a strong EASM and significant cooling over the two poles of the WNPOT (SKP and PS). These strengthened impacts of the ECP on the WNPOT and EASM contribute to the strengthened WNPOT-EASM relationship during P2. In addition, summer KER SST variability increases between 1991 and 2010, and this may have enhanced the impact of the KER on the EASM during P2. These two factors probably cause the EASM-related WNPO SSTA pattern to change from the WNPOD in P1 to the WNPOT in

  20. Variability of Atmospheric CO2 over the western North Pacific: Influence of Asian outflow during March-April 2001

    NASA Astrophysics Data System (ADS)

    Vay, S. A.; Woo, J.; Anderson, B. E.; Thornhill, K. L.; Kiley, C.; Avery, M. A.; Sachse, G. W.; Blake, D. R.; Streets, D. G.; Nolf, S. R.

    2002-12-01

    We report here tropospheric CO2 measurements made as part of the airborne component of NASA's Transport and Chemical Evolution over the Pacific (TRACE-P) Mission during March and April in 2001. CO2 mixing ratios, sampled in the subtropics (23.5-45.5° N) west of 150° E, exhibited a decreasing trend with height (0.5-12 km), were highly correlated with latitude showing a distinct north to south gradient, and peaked between 35-40° N within the planetary boundary layer. Near the Asian continent, discrete plumes encountered below 4 km contained up to 393.6 ppmv CO2 and were augmented with the combustion and industrial tracers CO, C2H6, C3H8, CH3Cl, C2Cl4, and C6H6. A chemically based air mass classification scheme using the combustion products CO and C2H2 as tracers of continental source emissions was employed in this analysis. Results show an excellent positive correlation for CO2 (r2=0.98) with respect to this ratio in the lower to mid free troposphere (4-8 km) providing evidence of continental outflow. South of the Tropic of Cancer, mean and median CO2 values derived from samples obtained below 8 km are less than those calculated for the subtropics. However, within the upper troposphere (UT) of both regions, similar values were determined and enhancements in combustion-derived species in the 8-12 km altitude range were observed. The relationship revealed between CO2 and the C2H2/CO ratio, particularly for the tropics, suggests recent inputs from the surface to the UT. In order to elucidate the processes determining the variations of CO2 in the Asian Pacific rim region during TRACE-P, a CO2 emissions data base developed for Asia was examined in conjunction with the chemistry and 5 day backward trajectories in an attempt to link CO2 enhancements observed in pollution plumes to source regions. From these data acquired downwind of the Asian continent when CO2 concentrations at the surface were approaching their seasonal maximum, we estimate a net export flux on the

  1. Reorganization of North Pacific Ocean Circulation at ~1300 AD during the Terminal American SW Drought of the Medieval Climate Anomaly

    NASA Astrophysics Data System (ADS)

    Hendy, I. L.; Pak, D. K.; Schimmelmann, A.

    2012-12-01

    Southern California has a Mediterranean-type climate characterized by warm, dry summers associated with the seasonal position of the North Pacific High and cool, wet winters primarily associated with cyclonic storms originating in the high latitude North Pacific. Extreme precipitation events in the region are associated, however, with strong zonal flow that brings warm, moist tropical air across the Pacific (atmospheric rivers). Here we present an ultra-high resolution reconstruction of riverine input (via scanning XRF elemental composition of bulk sediments) into Santa Barbara Basin during the Medieval Climate Anomaly (MCA) and transition into the Little Ice Age (LIA) from a series of kasten cores collected in 2009 by the RV Sproul. We compare precipitation shifts in the region with the response of marine biota to ocean circulation change during the same interval to demonstrate that not all droughts in the America Southwest are associated with the same atmospheric and ocean circulation conditions. Droughts are expressed in Santa Barbara Basin sediments by low concentrations of elements associated with lithogenic sediment (Ti, K, Al and Fe) and were centered at 890, 980, 1140 and 1450 AD. The SBB droughts of the MCA were interrupted by flood events at ˜1270 AD and ˜1380 AD ± 15 which were associated with a dramatic increase in the abundance of the subpolar planktonic foraminiferal sp. Neoglobogerina pachyderma (sinistral). Although variable, this interval dominated by a foraminiferal species preferring water <10°C lasted from ˜1275 to 1340 AD with a brief return to dominantly subtropical planktonic foraminferal species between 1340 and 1400 AD before the foraminiferal assemblage shifted toward cooler subpolar species again until >1500 AD. Of the major Native American population declines during the MCA coincident with drought conditions (990-1060 AD, 1135-1170 AD and 1276-1297 AD) in the Western US (Benson et al., 2007), only the last decline associated with

  2. Bloom Chasing With a Wave Glider: The MAGI (Mesoscale Features Aggregates Interaction) Project in the North Pacific

    NASA Astrophysics Data System (ADS)

    Wilson, C.; Villareal, T. A.; Anderson, E.

    2015-12-01

    Satellite ocean color data over the past decade has revealed the existence of large phytoplankton blooms in the North Pacific Ocean - specifically in the region NE of Hawai´I near 30°N. These blooms cover thousands of km2, persist for weeks or longer, and are often dominated by nitrogen-fixing diatom symbioses. These events have proven difficult to study outside of the time series station ALOHA at Hawai´i. The limited data indicates that the 30°N blooms are longer-lived, larger, and occur at a greater temperature range than the blooms that develop closer to Hawai´i. In the NE Pacific, at least some of these blooms occur at or near the subtropical front, a salinity-defined temperature compensated frontal zone that has a number of fronts imbedded in it. Here we will report on the results from the MAGI (Mesoscale features Aggregates Interaction) project. In this project, we deployed a Liquid Robotics SV2 Wave Glider® in June, 2015 for a multiple (up to 6) month mission to sample these features and assist in characterizing the bloom dynamics of this region. The Wave Gliders are the first unmanned autonomous marine robots to use only the ocean's wave energy for propulsion. The gliders are navigated remotely allowing a dynamic route through the keying of unique waypoints. Waypoints can be changed to sample features as they develop in the near-real time satellite imagery. The wave glider named Honey Badger is equipped with a CTD, two C3 fluorometers (one with an anti-biofouling coating applied), a Turner Designs PhytoFlash, meteorology and wave sensors, a downward facing camera, a Vengmar passive acoustic monitor, and a towed LISST-Holo.

  3. Metabolic balance in the mixed layer of the oligotrophic North Pacific Ocean from diel changes in O2/Ar saturation ratios

    NASA Astrophysics Data System (ADS)

    Ferrón, Sara; Wilson, Samuel T.; Martínez-García, Sandra; Quay, Paul D.; Karl, David M.

    2015-05-01

    In situ measurements were made to determine oxygen (O2) metabolic balance in the upper oligotrophic ocean from diel changes in O2 to argon (Ar) ratios. The study took place during 13-24 March 2014, at the Hawaii Ocean Time-series Station ALOHA (A Long-term Oligotrophic Habitat Assessment), in the North Pacific Subtropical Gyre. Microbial community respiration and gross O2 production, estimated from in situ diel changes in O2/Ar saturation, agreed well with those calculated using other independent methods. Net oxygen production (NOP), estimated from in situ diel changes in O2/Ar saturation, showed large day-to-day variability. However, when averaged over the entire observational period, mean diel NOP was in relatively good agreement with the estimated mean steady state NOP (9.2 ± 9.3 mmol O2 m-2 d-1 compared to 11.7 ± 1.1 mmol O2 m-2 d-1, respectively).

  4. Discrepant estimates of primary and export production from satellite algorithms, a biogeochemical model, and geochemical tracer measurements in the North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Palevsky, Hilary I.; Quay, Paul D.; Nicholson, David P.

    2016-08-01

    Estimates of primary and export production (PP and EP) based on satellite remote sensing algorithms and global biogeochemical models are widely used to provide year-round global coverage not available from direct observations. However, observational data to validate these approaches are limited. We find that no single satellite algorithm or model can reproduce seasonal and annual geochemically determined PP, export efficiency (EP/PP), and EP rates throughout the North Pacific basin, based on comparisons throughout the full annual cycle at time series stations in the subarctic and subtropical gyres and basin-wide regions sampled by container ship transects. The high-latitude regions show large PP discrepancies in winter and spring and strong effects of deep winter mixed layers on annual EP that cannot be accounted for in current satellite-based approaches. These results underscore the need to evaluate satellite- and model-based estimates using multiple productivity parameters measured over broad ocean regions throughout the annual cycle.

  5. Distribution of Rn-222 over the north Pacific - Implications for continental influences

    NASA Astrophysics Data System (ADS)

    Balkanski, Yves J.; Jacob, Daniel J.; Arimoto, Richard; Kritz, Mark A.

    1992-04-01

    The atmospheric distribution of Rn-222 over the north Pacific is simulated with a three-dimensional chemical tracer model using meteorological input from the NASA-GISS general circulation model (4 deg x 5 deg resolution). Radon-222 (half-life 3.8 days) is a tracer of continental air. Model results are in good agreement with measurements from ships and aircraft. Strong Asian influence is found throughout the tropospheric column over the north Pacific in spring, reflecting a combination of frequent convection over the continent, strong westerly winds at altitude, and subsidence over the ocean. In summer, the upper troposphere over the north Pacific is heavily affected by deep convection over China; however, Asian influences at the surface are then at their yearly minimum. In winter, strong Asian influence is found near the surface but not at high altitudes. Transport of American air over the Pacific is important only at low latitudes. American sources account for 11 percent of total Rn-222 in the model at Midway, 30 percent at Mauna Loa and 59 percent at Oahu. Results for Hawaii indicate two seasonal peaks of American influence, one in summer and one in winter. The tropical western Pacific is particularly remote from continental influences year round.

  6. A new species of Nezumia (Gadiformes: Macrouridae) from Fieberling Guyot, eastern North Pacific Ocean.

    PubMed

    Wilson, R R

    2001-07-01

    A new species of the macrourine genus Nezumia is described from specimens collected from the crest of Fieberling Guyot in the eastern North Pacific Ocean. The new species is distinguishable from all other Nezumia species chiefly on the basis of a high number of pelvic fin rays, a relatively high number of first dorsal fin soft rays, a steep blunt snout lacking scales ventrally, a relatively weak suborbital ridge, and a moderately long, thin barbel. Although possibly endemic to the Baja California Seamount Province, the new species appears to lack close relatives among the other Nezumia species of the eastern North Pacific Ocean. It might have arrived there either from a disjunct Tethyan distribution, thus retaining close relatives among the Atlantic Ocean species of Nezumia, or by way of stepping-stone dispersal from the Indo-west Pacific Ocean.

  7. Tectonic implications of post-30 Ma Pacific and North American relative plate motions

    USGS Publications Warehouse

    Bohannon, R.G.; Parsons, T.

    1995-01-01

    The Pacific plate moved northwest relative to North America since 42 Ma. The rapid half rate of Pacific-Farallon spreading allowed the ridge to approach the continent at about 29 Ma. Extinct spreading ridges that occur offshore along 65% of the margin document that fragments of the subducted Farallon slab became captured by the Pacific plate and assumed its motion proper to the actual subduction of the spreading ridge. This plate-capture process can be used to explain much of the post-29 Ma Cordilleran North America extension, strike slip, and the inland jump of oceanic spreading in the Gulf of California. Much of the post-29 Ma continental tectonism is the result of the strong traction imposed on the deep part of the continental crust by the gently inclined slab of subducted oceanic lithosphere as it moved to the northwest relative to the overlying continent. -from Authors

  8. 76 FR 66274 - North Pacific Fishery Management Council (NPFMC); Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-26

    ...) Groundfish Plan Teams will meet in Seattle. DATES: November 14-18, 2011. The meetings will begin at 9 a.m... (GOA Plan Team) and Traynor Room (BS/AI Plan Team), Seattle, WA. Council address: North Pacific Fishery... Teams will compile and review the annual Groundfish Stock Assessment and Fishery Evaluation Report...

  9. North Pacific region in the Paleogene and Neogene as an example of a semiclosed marine system

    NASA Astrophysics Data System (ADS)

    Gladenkov, Yu. B.

    2015-07-01

    Scenarios of different geological events in the Paleogene and Neogene evolution of the North Pacific ecosystem are considered with definition of five large stages in its development. The formation of biotic communities of large semiclosed systems in paratropical and boreal paleoenvironmemts, rates of their evolution, and influence of migration on their development are reconstructed.

  10. Atlas of Nonindigenous Marine and Estuarine Species in the North Pacific

    EPA Science Inventory

    The product consists of a report synthesizing available information on nonindigenous species in the North Pacific. We note that while this product focuses on invasive species, the tools and approaches developed for this research are the precursors on how we will address identifyi...

  11. Evolution of biogeography in the 21st Century - Development of a North Pacific Nonindigenous Species Database

    EPA Science Inventory

    Aquatic invasive species are one of the major ecological threats to the ecological integrity of estuarine and near-coastal waters. However, lack of systematic inventories of nonindigenous species across the North Pacific countries limits our ability to assess how the extent of i...

  12. Carbon Cycling in the Arctic Archipelago: The Export of Pacific Carbon to the North Atlantic

    NASA Astrophysics Data System (ADS)

    Shadwick, E. H.; Papakyriakou, T.; Prowe, A. E. F.; Leong, D.; Moore, S.; Thomas, H.

    2009-04-01

    The Arctic Ocean is expected to be disproportionately sensitive to climatic changes, and thought to be an area where such changes might be detected. The Arctic hydrological cycle is influenced by: runoff and precipitation, sea ice formation/melting, and the inflow of saline waters from Bering and Fram Straits and the Barents Sea Shelf. Pacific water is recognizable as low salinity water, with high concentrations of dissolved inorganic carbon (DIC), flowing from the Arctic Ocean to the North Atlantic via the Canadian Arctic Archipelago. We present DIC data from an east-west section through the Archipelago, as part of the Canadian International Polar Year initiatives. The fractions of Pacific and Arctic Ocean waters leaving the Archipelago and entering Baffin Bay, and subsequently the North Atlantic, are computed. The eastward transport of carbon from the Pacific, via the Arctic, to the North Atlantic is estimated. Altered mixing ratios of Pacific and freshwater in the Arctic Ocean have been recorded in recent decades. Any climatically driven alterations in the composition of waters leaving the Arctic Archipelago may have implications for anthropogenic CO2 uptake, and hence ocean acidification, in the subpolar and temperate North Atlantic.

  13. Carbon cycling in the Arctic Archipelago: the export of Pacific carbon to the North Atlantic

    NASA Astrophysics Data System (ADS)

    Shadwick, E. H.; Papakyriakou, T.; Prowe, A. E. F.; Leong, D.; Moore, S. A.; Thomas, H.

    2009-01-01

    The Arctic Ocean is expected to be disproportionately sensitive to climatic changes, and is thought to be an area where such changes might be detected. The Arctic hydrological cycle is influenced by: runoff and precipitation, sea ice formation/melting, and the inflow of saline waters from Bering and Fram Straits and the Barents Sea Shelf. Pacific water is recognizable as intermediate salinity water, with high concentrations of dissolved inorganic carbon (DIC), flowing from the Arctic Ocean to the North Atlantic via the Canadian Arctic Archipelago. We present DIC data from an east-west section through the Archipelago, as part of the Canadian International Polar Year initiatives. The fractions of Pacific and Arctic Ocean waters leaving the Archipelago and entering Baffin Bay, and subsequently the North Atlantic, are computed. The eastward transport of carbon from the Pacific, via the Arctic, to the North Atlantic is estimated. Altered mixing ratios of Pacific and freshwater in the Arctic Ocean have been recorded in recent decades. Any climatically driven alterations in the composition of waters leaving the Arctic Archipelago may have implications for anthropogenic CO2 uptake, and hence ocean acidification, in the subpolar and temperate North Atlantic.

  14. Changes in size and trends of North American sea duck populations associated with North Pacific oceanic regime shifts

    USGS Publications Warehouse

    Flint, Paul L.

    2013-01-01

    Broad-scale multi-species declines in populations of North American sea ducks for unknown reasons is cause for management concern. Oceanic regime shifts have been associated with rapid changes in ecosystem structure of the North Pacific and Bering Sea. However, relatively little is known about potential effects of these changes in oceanic conditions on marine bird populations at broad scales. I examined changes in North American breeding populations of sea ducks from 1957 to 2011 in relation to potential oceanic regime shifts in the North Pacific in 1977, 1989, and 1998. There was strong support for population-level effects of regime shifts in 1977 and 1989, but little support for an effect of the 1998 shift. The continental-level effects of these regime shifts differed across species groups and time. Based on patterns of sea duck population dynamics associated with regime shifts, it is unclear if the mechanism of change relates to survival or reproduction. Results of this analysis support the hypothesis that population size and trends of North American sea ducks are strongly influenced by oceanic conditions. The perceived population declines appear to have halted >20 years ago, and populations have been relatively stable or increasing since that time. Given these results, we should reasonably expect dramatic changes in sea duck population status and trends with future oceanic regime shifts.

  15. A revised estimate of Pacific-North America motion and implications for Western North America plate boundary zone tectonics

    NASA Technical Reports Server (NTRS)

    Demets, Charles; Gordon, Richard G.; Stein, Seth; Argus, Donald F.

    1987-01-01

    Marine magnetic profiles from the Gulf of Californa are studied in order to revise the estimate of Pacific-North America motion. It is found that since 3 Ma spreading has averaged 48 mm/yr, consistent with a new global plate motion model derived without any data. The present data suggest that strike-slip motion on faults west of the San Andreas is less than previously thought, reducing the San Andreas discrepancy with geodetic, seismological, and other geologic observations.

  16. 78 FR 41033 - Fisheries of the Northeast Region, Southeast Region, North Pacific Region, Pacific Region...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-09

    ... experiencing overfishing and is now in an overfished condition. The Southwest Fisheries Science Center affirmed that the ISC stock assessment was the best available science. Pacific bluefin tuna is considered to be... (ii) the IATTC and WCPFC have inadequate measures in place to correct the problem. Therefore,...

  17. North Atlantic summer to winter rainfall response to the Atlantic-Pacific tropical connection

    NASA Astrophysics Data System (ADS)

    Rodríguez-Fonseca, Belen; Losada Doval, Teresa; Mohino Harris, Elsa; Polo Sánchez, Irene; Garcia Serrano, Javier

    2010-05-01

    Recent observational and GCM studies have shown, following the results of Polo et al. (2008), how the Atlantic and Pacific Niños present a dynamical link during the last decades of the XX century (Rodriguez-Fonseca et al., 2009). In this way, the positive (negative) phase of the summer Pacific Niño signal has been found to be connected with a negative (positive) phase of the Equatorial Atlantic mode (EM or Atlantic Niño, Polo et al., 2008); a pattern which leads the summer Atlantic variability. The determinant impact of this connection on the WA monsoon has been addressed by defining a global summer tropical mode accounting for more than the 60% of the rainfall variance. The rainfall response to an isolated Pacific forcing has been documented to be a decrease of rainfall over Sahel whilst, the response associated to an isolated EM is a Guinean-Sahel rainfall dipolar pattern. Nevertheless, the rainfall response to the Pacific ENSO- Atlantic Niña forcing observed from the 70's has a unified behavior in the WA region. In order to deeply analyse the dynamics involved in the concomitant action of the Atlantic and Pacific in summer and in the subsequent months, different sensitivity experiments have been performed separating the global Atlantic-IndoPacific contribution to the independent Pacific and Atlantic ones. Some dynamical aspects in relation to the extratropical North Atlantic teleconnections in the following seasons are also included.

  18. Effect of biomass burning over the western North Pacific Rim: wintertime maxima of anhydrosugars in ambient aerosols from Okinawa

    NASA Astrophysics Data System (ADS)

    Zhu, C.; Kawamura, K.; Kunwar, B.

    2015-02-01

    Biomass burning (BB) largely modifies the chemical composition of atmospheric aerosols on the globe. We collected aerosol samples (TSP) at Cape Hedo, on subtropical Okinawa Island, from October 2009 to February 2012 to study anhydrosugars as BB tracers. Levoglucosan was detected as the dominant anhydrosugar followed by its isomers, mannosan and galactosan. We found a clear seasonal trend of levoglucosan and mannosan with winter maxima and summer minima. Positive correlation was found between levoglucosan and nss-K+ (r = 0.38, p < 0.001); the latter is another BB tracer. The analyses of air mass trajectories and fire spots demonstrated that the seasonal variations of anhydrosugars are caused by long-range transport of BB emissions from the Asian continent. We found winter maxima of anhydrosugars, which may be associated with open burning and domestic heating and cooking in northern and northeastern China, Mongolia and Russia and with the enhanced westerly winds. The monthly averaged levoglucosan / mannosan ratios were lower (2.1-4.8) in May-June and higher (13.3-13.9) in November-December. The lower values may be associated with softwood burning in northern China, Korea and southwestern Japan whereas the higher values are probably caused by agricultural waste burning of maize straw in the North China Plain. Anhydrosugars comprised 0.22% of water-soluble organic carbon (WSOC) and 0.13% of organic carbon (OC). The highest values to WSOC (0.37%) and OC (0.25%) were found in winter, again indicating an important BB contribution to Okinawa aerosols in winter. This study provides useful information to better understand the effect of East Asian biomass burning on the air quality in the western North Pacific Rim.

  19. Variability within the ocean-atmospheric system over the North Pacific

    SciTech Connect

    Ciesielski, P E

    1980-01-01

    Characteristics of the oceanic mixed layer over the North Pacific were examined utilizing a number of statistical methods. Based on the analyses of twelve years of data, a quasi-meridional differentiation (QMD) in sea surface temperature (SST) spectra across the North Pacific was observed. The SST spectra became increasingly red as an increasing function of latitude. A strong 21 to 26 day cycle in SST anomalies is discussed which may be a reflection of heat fluxes. These fluxes also vacillate significantly on this time-scale in conjunction with cycles observed in the atmospheric energy modes of available potential and kinetic energy. Examination of an oceanic heat budget on a spatial and temporal basis suggest that the impact of latent and sensible heat fluxes upon ..delta..SST is partially a function of the magnitude of the heat fluxes as well as of the depth to which their effects are mixed. The heat budget analyses and the fitting of power spectra of SST anomalies over the North Pacific to a two-parameter oceanic model, suggest that SST behavior over the mid-oceanic regions of the North Pacific is dominated by the influence of latent and sensible heat fluxes. On the other hand, over the remainder of the North Pacific one could surmise that other processes, such as advection of heat within the ocean, the entrainment heat flux at the base of the mixed layer, and radiation are at least as important in determining the behavior of SST's. By analyzing anomalous patterns of atmospheric thickness and SST's, it appears that the modification of air masses as they are advected over oceanic waters, as well as the stability of the lower atmosphere, are instrumental factors in determining the nature of large-scale air-sea heat exchange processes.

  20. Diversity and composition of sediment bacteria in subtropical coastal wetlands of North Stradbroke Island, Queensland, Australia

    NASA Astrophysics Data System (ADS)

    Chuvochina, Maria; Sampayo, Eugenia; Welti, Nina; Hayes, Matthew; Lu, Yang; Lovelock, Catherine; Lockington, David

    2013-04-01

    Coastal wetlands provide a wide variety of important ecosystem services but continue to suffer disturbance, degradation and deforestation. Sediment bacteria are responsible for major nutrient transformation and recycling in these ecosystems. Insight into microbial community composition and the factors that determine them may improve our understanding of biogeochemical processes, food web dynamics, biodegradation processes and, thus, help to develop the management strategies for preserving the ecosystem health and services. Characterizing shifts in community taxa along environmental gradients has been shown to provide a useful tool for determining the major drivers affecting community structure and function. North Stradbroke Island (NSI) in Southern Queensland presents considerable habitat diversity including variety of groundwater dependent ecosystems such as lakes, swamps, sedge-like salt marshes and mangroves. Ecological responses of continuous groundwater extraction for municipal purposes and sand mining operations on NSI are still need to be assessed in order to protect its unique environment. Changes in coastal hydrology due to either climate change or human activity may directly affect microbial populations and, thus, biogeochemical cycles of nutrients. These may result in altering/losing some ecosystem services provided by coastal wetlands. In this study we examine microbial diversity and determine environmental controls on bacterial community structure along a natural transition from freshwater forested wetland (melaleuca woodland), sedge-like salt marsh and into mangroves located at NSI. The study area is characterized by significant groundwater flow, nutrient limitation and sharp transition from one ecosystem type to another. Sediment cores (0-5 cm and 20-25 cm depth) were collected from three representative sites of each zone (mangroves - salt marsh - freshwater wetland) along the salinity gradient in August 2012. Subsamples were set aside for use in

  1. 75 FR 66071 - North Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-27

    ... Council's (NPFMC) Gulf of Alaska (GOA) and Bering Sea/Aleutian Islands (BS/AI) Groundfish plan teams will... Training Room (GOA Plan Team) and Traynor Room (BS/AI Plan Team), Seattle, WA. Council address: North...: The plan teams will prepare and review the stock ] assessments for groundfish fisheries in the...

  2. Exploring Paleoclimatic and -Oceanographic Consequences for Arctic Beringia by the Eocene Formation and Progressive E-W Lengthening of the Aleutian Ridge (arc) Across the North Pacific Basin

    NASA Astrophysics Data System (ADS)

    Scholl, D. W.

    2013-12-01

    westward toward Kamchatka. Water-exchange passes were created between them as the AR tectonically lengthened to ~2200 km at an estimated average speed of ~40-50 km/Myr. PALEOCEANOGRPAIC WONDERMENTS FOR PACIFIC SECTOR OF ARCTIC: The Arctic Ocean presently receives low salinity water entering the BS from the east. Prior to Northern Hemisphere glaciation, fossil plant and animal taxa document the BS was far more temperature than the cold, foggy, rawness of today, and surface waters were saltier and warmer than now. Although the BSB is today effectively closed to north-bound western Pacific circulation, during much of Tertiary it was open to the west. It can be posited that subtopical, western Pacific boundary currents (e.g., the Kuroshio Current) formerly entered the BS from the west and exited eastward--the reverse of now. Salty surface water in the BSB could have supported THC to begin construction of the Meiji drift body by southward outflow of abyssal BS water through Kamchatka Strait. To the north, when the Tertiary Bering Strait was open, BS water entering the Arctic Ocean may well have been sourced from the western subtropical Pacific rather than, as now, from the subboreal NE Pacific.

  3. Diversity of Diazotrophic Unicellular Cyanobacteria in the Tropical North Atlantic Ocean

    PubMed Central

    Falcón, Luisa I.; Cipriano, Frank; Chistoserdov, Andrei Y.; Carpenter, Edward J.

    2002-01-01

    We present data on the genetic diversity and phylogenetic affinities of N2-fixing unicellular cyanobacteria in the plankton of the tropical North Atlantic Ocean. Our dinitrogenase gene (nifH) sequences grouped together with a group of cyanobacteria from the subtropical North Pacific; another subtropical North Pacific group was only distantly related. Most of the 16S ribosomal DNA sequences from our tropical North Atlantic samples were closely allied with sequences from a symbiont of the diatom Climacodium frauenfeldianum. These findings suggest a complex pattern of evolutionary and ecological divergence among unicellular cyanobacteria within and between ocean basins. PMID:12406777

  4. Pathways of the North Pacific Intermediate Water identified through the tangent linear and adjoint models of an ocean general circulation model

    NASA Astrophysics Data System (ADS)

    Fujii, Y.; Nakano, T.; Usui, N.; Matsumoto, S.; Tsujino, H.; Kamachi, M.

    2014-12-01

    This study develops a strategy for tracing a target water mass, and applies it to analyzing the pathway of the North Pacific Intermediate Water (NPIW) from the subarctic gyre to the northwestern part of the subtropical gyre south of Japan in a simulation of an ocean general circulation model. This strategy estimates the pathway of the water mass that travels from an origin to a destination area during a specific period using a conservation property concerning tangent linear and adjoint models. In our analysis, a large fraction of the low salinity origin water mass of NPIW initially comes from the Okhotsk or Bering Sea, flows through the southeastern side of the Kuril Islands, and is advected to the Mixed Water Region (MWR) by the Oyashio current. It then enters the Kuroshio Extension (KE) at the first KE ridge, and is advected eastward by the KE current. However, it deviates southward from the KE axis around 158°E over the Shatsky Rise, or around 170ºE on the western side of the Emperor Seamount Chain, and enters the subtropical gyre. It is finally transported westward by the recirculation flow. This pathway corresponds well to the shortcut route of NPIW from MWR to the region south of Japan inferred from analysis of the long-term freshening trend of NPIW observation.

  5. Southwest intrusion of 134Cs and 137Cs derived from the Fukushima Dai-ichi nuclear power plant accident in the Western North Pacific.

    PubMed

    Kaeriyama, Hideki; Shimizu, Yugo; Ambe, Daisuke; Masujima, Masachika; Shigenobu, Yuya; Fujimoto, Ken; Ono, Tsuneo; Nishiuchi, Kou; Taneda, Takeshi; Kurogi, Hiroaki; Setou, Takashi; Sugisaki, Hiroya; Ichikawa, Tadafumi; Hidaka, Kiyotaka; Hiroe, Yutaka; Kusaka, Akira; Kodama, Taketoshi; Kuriyama, Mikiko; Morita, Hiroshi; Nakata, Kaoru; Morinaga, Kenji; Morita, Takami; Watanabe, Tomowo

    2014-03-18

    Enormous quantities of radionuclides were released into the ocean via both atmospheric deposition and direct release as a result of the Fukushima Dai-ichi Nuclear Power Plant (FNPP) accident. This study discusses the southward dispersion of FNPP-derived radioactive cesium (Cs) in subsurface waters. The southernmost point where we found the FNPP-derived (134)Cs (1.5-6.8 Bq m(-3)) was 18 °N, 135 °E, in September 2012. The potential density at the subsurface peaks of (134)Cs (100-500 m) and the increased water column inventories of (137)Cs between 0 and 500 m after the winter of 2011-2012 suggested that the main water mass containing FNPP-derived radioactive Cs was the North Pacific Subtropical Mode Water (NPSTMW), formed as a result of winter convection. We estimated the amount of (134)Cs in core waters of the western part of the NPSTMW to be 0.99 PBq (decay-corrected on 11 March 2011). This accounts for 9.0% of the (134)Cs released from the FNPP, with our estimation revealing that a considerable amount of FNPP-derived radioactive Cs has been transported to the subtropical region by the formation and circulation of the mode water.

  6. Concentration and toxic potential of polychlorinated biphenyl congeners in migratory oceanic birds from the North Pacific and the Southern Ocean.

    PubMed

    Guruge, K S; Tanaka, H; Tanabe, S

    2001-09-01

    Concentrations of PCBs and their toxic potential were examined in subcutaneous fat of eight albatross and one petrel species collected from the North Pacific and the Southern Oceans. Among all the species analyzed, high PCB levels were found in adult male blackfooted albatross from the North Pacific with the mean value of 92 microg/g wet weight. No significant gender difference in PCB accumulation was observed (P>0.1). The mean PCB levels in Southern Oceanic birds were 1 or 2 orders of magnitude lower than those from the North Pacific albatrosses. A regional-specific accumulation of non-ortho coplanar congeners were observed, most birds from the Southern Ocean had higher IUPAC 169 levels while IUPAC 126 concentrations were higher in those from the North Pacific. The estimated toxic equivalents for black-footed and Laysan albatrosses from the North Pacific were in the same range of some fish-eating birds, which were highly contaminated by PCBs. The correlation between ratio of IUPAC 169/126 concentration and total PCBs concentration indicated the possibility of induction in cytochrome P450 activities in North Pacific albatrosses (P<0.01). The calculated hazard indices indicated that black-footed and Laysan albatrosses inhabiting in the North Pacific had similar threshold levels which were known to cause toxic effects in some populations of fish-eating birds. PMID:11570807

  7. Seasonal Storminess in the North Pacific, Bering Sea, and Alaskan Regions

    NASA Astrophysics Data System (ADS)

    Shippee, N. J.; Atkinson, D. E.; Walsh, J. E.; Partain, J.; Gottschalck, J.; Marra, J.

    2012-12-01

    Annually, extra-tropical cyclones present a high impact natural hazard to the North Pacific, Bering Sea, and Alaskan regions. In these regions, extensive subsistence and commercial fishing, new oil and gas field development, tourism, growing interest in and exploitation of new commercial shipping potential, and increasing military and Coast Guard activity, all represent potential parties impacted by storms in these waters. It is of interest to many parties to begin developing capacity to provide some indication of storm activity at a monthly- to seasonal-outlook (30 to 90 days) timeframe. Using storm track data from NOAA's Climate Prediction Center for the North Pacific and Alaskan region, an experimental seasonal storminess outlook product, using eigen-based methods similar to the operational seasonal temperature and precipitation products currently produced at NOAA CPC, has been created and tested in hindcast mode using predicted states of ENSO, the Pacific Decadal Oscillation (PDO), the Pacific-North American Pattern (PNA), and the Arctic Oscillation (AO). A sample of the seasonal storminess outlook product will be shown along with a discussion of the utility of individual teleconnection patterns in the generation of the product.

  8. Sinking velocity of particulate radiocesium in the northwestern North Pacific

    NASA Astrophysics Data System (ADS)

    Honda, Makio C.; Kawakami, Hajime

    2014-06-01

    Sinking particles (SP) were collected by time series sediment traps at two depths in the northwestern Pacific before and after the Fukushima Daiichi Nuclear Power Plant accident, and accident-derived particulate radiocesium was measured. Radiocesium (137Cs) was first detected at 500 m (4810 m) about 2 weeks (1 month) after the accident. 137Cs of SP collected over 1 year revealed that the time lag between two depths was larger than that for the first 137Cs detection (about 2 weeks). We estimated the transient sinking velocity (SV) from the cumulative temporal 137Cs flux and the time lags at the two depths. Although the SV of SP collected in very early period was large, the estimated SV of most particulate 137Cs (about 80%) was about 50 m d-1. Based on comparison of 137Cs concentration in total SP with that in SP without organic materials, we suspect that most of the 137Cs was likely incorporated into aluminosilicates.

  9. Observation-based estimate of the Fukushima radionuclide in the North Pacific

    NASA Astrophysics Data System (ADS)

    Yoshida, Sachiko; Jayne, Steven; Macdonald, Alison; Buesseler, Ken; Rypina, Irina

    2014-05-01

    Contaminated waters from Fukushima nuclear power plant (FNPP) were discharged directly into the North Pacific Ocean in March 2011. Coastal current system in this region and time scale of the water exchange with the open ocean is not well understood, however both observational evidence and numerical model simulation results indicate relatively rapid advection of contaminants eastward into the highly energetic mixed water region in the confluence of the Kuroshio and Oyashio. Surface drifters deployed near the FNPP in early summer 2011 show trajectories crossing the North Pacific generally following the large scale ocean circulation after one year. Previously obtained cesium (Cs) samples from multiple cruises near FNPP and off shore region between 2011 and 2013 are collected and evaluated to diagnose the propagating Cs signal crossing North Pacific Ocean. In this presentation, we use radionuclides of Fukushima origin as a tracer to understand the North Pacific circulation and mixing process after two years of release. Large numbers of the observation are repeatedly took place near shore where Cs shows still relatively higher about 10-30 Bq/m3 in 2013. Temperature-salinity (T-S) properties for the available hydrographic data indicate that the majority of the samples were obtained in the region where the water is highly influenced by the warm-salty Kuroshio origin water. Depth profiles of 35N section in March-May 2013 cruise of the U.S. Climate Variability and Predictability and Carbon (CLIVAR) repeat Hydrography sections are examined to track the radionuclide penetration into the subsurface ocean and the subduction pathways along isopycnal surfaces. Available large drifter datasets that accumulated over decades of field work can guide us in estimating the spread of these radionuclides. By applying an innovative statistical analysis to the drifter data, we investigate the spreading of radionuclides in the Pacific Ocean over 5-year time scales.

  10. Accretion and hydrothermalism in North Fiji basin, Southwest Pacific

    SciTech Connect

    Auzende, J.M.; Eissen, J.P.

    1986-07-01

    The North Fiji basin is a marginal basin surrounded by: (1) the New Hebrides island arc in the west, which ends at the Matthew-Hunter Ridge in the south; (2) the Hunter fracture zone in the southeast; (3) the Fiji Islands in the east; and (4) the complex Vitiaz Trench system in the north. The investigations in this area suggest a complex opening has been active for approximately the past 10 m.y. The detailed bathymetry and the structure of the central part of this basin are still poorly known. The major element consists of an axial ridge. The trend of this ridge is imprecise, but it is probably oriented north-south near 173.5/sup 0/E, at least between 21/sup 0/ and 15/sup 0/S. The other remarkable feature consists of a complex system of ridges and faulted blocks running along the western edge of the Fiji Archipelago. This system has been interpreted by some authors as an accretion ridge. The purposes of the third leg of SEAPSO cruise onboard the R/V Jean-Charcot (December 2-24, 1985) are as follows: (1) to explore the typical structures of the North Fiji basin between 21/sup 0/ and 17/sup 0/S (axial ridge, seamounts, fracture zones, and the complex border west of Fiji), using multibeam echo-sounder (Seabeam), seismic reflection, magnetic, and gravimetric surveys; and (2) to complete Seabeam coverage and samplings (such as dredging, coring, water sampling, and bottom photographs) of two to three small box-shaped areas on the axial ridge, in order to localize and eventually characterize hydrothermal vents. The various morphotectonic, petrologic, chemical, and geodynamic results of this survey will be discussed.

  11. Ocean eddies generated by seamounts in the north pacific.

    PubMed

    Royer, T C

    1978-03-10

    Small-scale (diameters of about 37 kilometers) fluctuations in dynamic topography north of Hawaii along 158 degrees W are well correlated with upstream seamounts. The fluctuations are subsurface but are manifested as baroclinic eddies at the sea surface. These eddies are confirmed by direct observations and supported by theoretical considerations. The eddies cause small-scale variability in the currents and hydrographic structures in this area, and they should be considered in any sampling programs of the region.

  12. Relationship of boreal summer 10-20-day and 30-60-day intraseasonal oscillation intensity over the tropical western North Pacific to tropical Indo-Pacific SST

    NASA Astrophysics Data System (ADS)

    Wu, Renguang; Cao, Xi

    2016-07-01

    The present study contrasts interannual variations in the intensity of boreal summer 10-20-day and 30-60-day intraseasonal oscillations (ISOs) over the tropical western North Pacific and their factors. A pronounced difference is found in the relationship of the two ISOs to El Niño-Southern Oscillation. The 10-20-day ISO intensity is enhanced during El Niño developing summer, whereas the 30-60-day ISO intensity is enhanced during La Niña decaying summer. The above different relationship is interpreted as follows. The equatorial central and eastern Pacific SST anomalies modify vertical wind shear, lower-level moisture, and vertical motion in a southeast-northwest oriented band from the equatorial western Pacific to the tropical western North Pacific where the 10-20-day ISOs originate and propagate. These background field changes modulate the amplitude of 10-20-day ISOs. Preceding equatorial central and eastern Pacific SST anomalies induce SST anomalies in the North Indian Ocean in summer, which in turn modify vertical wind shear and vertical motion over the tropical western North Pacific. The modified background fields influence the amplitude of the 30-60-day ISOs when they reach the tropical western North Pacific from the equatorial region. A feedback of ISO intensity on local SST change is identified in the tropical western North Pacific likely due to a net effect of ISOs on surface heat flux anomalies. This feedback is more prominent from the 10-20-day than the 30-60-day ISO intensity change.