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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. Local stratification control of marine productivity in the subtropical North Pacific

    NASA Astrophysics Data System (ADS)

    Dave, Apurva C.; Lozier, M. Susan

    2010-12-01

    Strengthened stratification of the upper ocean due to global warming is generally expected to inhibit marine primary productivity in the subtropics, based on the supposition that increased water column stability will decrease vertical mixing and consequently the entrainment of deep nutrients into the euphotic zone. A recent analysis of observational data from the subtropical North Atlantic, however, demonstrates that productivity in this region is not correlated with stratification on interannual time scales over the modern observational record, but is instead impacted by other dynamics that affect vertical mixing and nutrient supply. Herein, we examine data from the Hawaiian Ocean Time series program's Station ALOHA (A Long-Term Oligotrophic Habitat Assessment) in the subtropical North Pacific. We find that stratification and productivity are not strongly correlated at this location over the observational record. In contrast to the North Atlantic, the weakness of correlation observed at ALOHA may reflect the strongly stratified ecosystem of the eastern subtropical North Pacific and a lack of sufficiently strong interannual forcing in this region. Although basin-wide climate processes (namely El Niño-Southern Oscillation and Pacific Decadel Oscillation) have previously been suggested to impact local stratification and vertical nutrient supply at ALOHA, we find no evidence of a strong or consistent linkage. Comparing local ecosystem variability to the recently identified North Pacific Gyre Oscillation, however, we observe a correlation with local subsurface productivity and salinity. The correlations have similar structure in both space (i.e., depth) and time and are possibly linked to dynamics associated with the formation and advection of water masses in the central gyre.

  5. Nitrogen fixation by Trichodesmium spp. and unicellular diazotrophs in the North Pacific Subtropical Gyre

    NASA Astrophysics Data System (ADS)

    Sohm, Jill A.; Subramaniam, Ajit; Gunderson, Troy E.; Carpenter, Edward J.; Capone, Douglas G.

    2011-09-01

    Nitrogen (N2) fixation is an important process that fuels export production in the North Pacific Ocean, as evidenced by seasonally low δ15N of sinking organic nitrogen (N) at the Hawaii Ocean Time series station. However, relatively few direct measurements of N2 fixation exist across the North Pacific. On two cruises there in fall 2002 and summer 2003, the abundance and N2 fixation rate of Trichodesmium spp. and Richelia, as well as bulk water samples, were measured. Trichodesmium spp. were only detected in the area near the Hawaiian Islands, in similar densities on both cruises. Despite similar densities, the areal N2 fixation rate of Trichodesmium spp. in fall 2002 was nearly four times greater than in summer 2003 at stations proximal to the Hawaiian Islands. In the central North Pacific Gyre far from the Hawaiian Islands, where Trichodesmium spp. was not present, whole water N2 fixation rates were relatively high (˜100 μmol N m-2 d-1). Presumably unicellular diazotrophs were responsible for activity there. Our studies show a geographical variation in the dominant diazotroph in the North Pacific Subtropical Gyre in the summer with Trichodesmium being dominant around the Hawaiian Islands, Richelia associated with diatoms to be found in high numbers to the south of the islands while unicellular diazotrophs dominated to the west, away from the islands and evidence from the literature suggests iron may play a role.

  6. 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.

  7. 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.

  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. Summer Diatom Blooms in the North Pacific Subtropical Gyre: 2008–2009

    PubMed Central

    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 102–103 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 102–103 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

  10. 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.

  11. 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.

  12. How can anomalous western North Pacific Subtropical High intensify in late summer?

    NASA Astrophysics Data System (ADS)

    Xiang, Baoqiang; Wang, Bin; Yu, Weidong; Xu, Shibin

    2013-05-01

    The western North Pacific (WNP) Subtropical High (WNPSH) is a controlling system for East Asian Summer monsoon and tropical storm activities, whereas what maintains the anomalous summertime WNPSH has been a long-standing riddle. Here we demonstrate that the local convection-wind-evaporation-SST (CWES) feedback relying on both mean flows and mean precipitation is key in maintaining the WNPSH, while the remote forcing from the development of the El Niño/Southern Oscillation is secondary. Strikingly, the majority of strong WNPSH cases exhibit anomalous intensification in late summer (August), which is dominantly determined by the seasonal march of the mean state. That is, enhanced mean precipitation associated with strong WNP monsoon trough in late summer makes atmospheric response much more sensitive to local SST forcing than early summer.

  13. 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

  14. 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.

  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. Relationships between the tropical SST and summertime subtropical high over the western North Pacific

    NASA Astrophysics Data System (ADS)

    Chung, Pei-Hsuan; Sui, Chung-Hsiung; Li, Tim

    2010-05-01

    The interannual variability of the western North Pacific Subtropical High (WNPSH) in summer is investigated with the use of the NCEP/NCAR reanalysis data for the period of 1958-2005. The most significant change appears at the western edge of WNPSH, with dominant 2-3-yr and 3-5-yr power spectrum peaks. The 2-3-yr oscillation of WNPSH and associated circulation and sea surface temperature (SST) patterns possess a coherent eastward-propagating feature, with a warm SST anomaly (SSTA) and anomalous ascending motion migrating from the tropical Indian Ocean in the preceding winter to the maritime continent in the concurrent summer of a strong WNPSH. A strong WNPSH is characterized by anomalous anticyclonic circulation and maximum subsidence in the western North Pacific (WNP). The anomalous WNPSH circulation has an equivalent barotropic vertical structure and resides in the sinking branch of local Hadley circulation, triggered by enhanced convection over the maritime continent in the summer. A heat budget analysis reveals that WNPSH is maintained by radiative cooling, which overcomes the decent induced adiabatic warming. The 3-5-yr oscillation of WNPSH exhibits a quasi stationary feature, with a warm SSTA (anomalous ascending motion) located in the equatorial central-eastern Pacific and Indian Ocean and a cold SSTA (anomalous descending motion) located in the western Pacific. The anomaly pattern persists from the preceding winter to the concurrent summer of a high WNPSH. The maximum descent is located to the east of the anomalous anticyclone center, where a baroclinic vertical structure is identified. The anomalous anticyclone on this timescale is a Rossby wave response to a negative convective heating associated with the local cold SSTA.

  17. 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

  18. 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

  19. Biogenic silica cycling during summer phytoplankton blooms in the North Pacific subtropical gyre

    NASA Astrophysics Data System (ADS)

    Krause, Jeffrey W.; Brzezinski, Mark A.; Villareal, Tracy A.; Wilson, Cara

    2013-01-01

    Biogenic silica (bSiO2) cycling, diatom abundance and floristics were examined within summer-period diatom blooms in the North Pacific Subtropical Gyre (NPSG) in 2008 and 2009. Hemiaulus hauckii was the most abundant diatom observed in an expansive (100,000 km2) bloom near the subtropical front in the northeastern NPSG in 2008 and the small pennate diatom Mastogloia woodiana dominated a smaller (30,000 km2) bloom sampled in 2009 in the gyre interior. In both blooms, the bSiO2 stock and production rates were up to an order of magnitude higher relative to non-bloom areas. Remnants of a bSiO2 export event was sampled in the H. hauckii bloom area where the export rate at 300 m exceeded that at 150 m, and was among the highest values recorded in the NPSG. The M. woodiana bloom was very active with specific bSiO2 production rates of 0.50-0.75 d-1 and net bSiO2 production rates were among the highest observed in any subtropical-gyre diatom bloom to date. Net silica production rates in the euphotic zone were strongly positive within blooms and near zero outside of blooms, consistent with an important role for blooms in bSiO2 export. The difference in the areal extent of the H. hauckii and M. woodiana blooms was consistent with remote-sensing observations that blooms in the northeastern portion of the NPSG, near the subtropical front, are typically more extensive than those in the gyre interior near Hawaii Ocean Time-series station ALOHA. Initial estimates suggest that blooms in the northeast region produced 3-25 times more bSiO2 in 2008 and 2009, respectively, than did blooms in the gyre interior; and due to the large areal extent these blooms, their area-integrated production of bSiO2 is similar to intense diatom blooms coastal upwelling systems (e.g. Monterey Bay, Santa Barbara Channel) despite significantly lower production rates and standing stock.

  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. 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.

  2. Interannual variability of primary production and dissolved organic nitrogen storage in the North Pacific Subtropical Gyre

    NASA Astrophysics Data System (ADS)

    Luo, Ya-Wei; Ducklow, Hugh W.; Friedrichs, Marjorie A. M.; Church, Matthew J.; Karl, David M.; Doney, Scott C.

    2012-09-01

    The upper ocean primary production measurements from the Hawaii Ocean Time series (HOT) at Station ALOHA in the North Pacific Subtropical Gyre showed substantial variability over the last two decades. The annual average primary production varied within a limited range over 1991-1998, significantly increased in 1999-2000 and then gradually decreased afterwards. This variability was investigated using a one-dimensional ecosystem model. The long-term HOT observations were used to constrain the model by prescribing physical forcings and lower boundary conditions and optimizing the model parameters against data using data assimilation. The model reproduced the general interannual pattern in the observed primary production, and mesoscale variability in vertical velocity was identified as a major contributing factor to the interannual variability in the simulation. Several strong upwelling events occurred in 1999, which brought up nitrate at rates several times higher than other years and elevated the model primary production. Our model results suggested a hypothesis for the observed interannual variability pattern of primary production at Station ALOHA: Part of the upwelled nitrate input in 1999 was converted to and accumulated as semilabile dissolved organic nitrogen (DON), and subsequent recycling of this semilabile DON supported enhanced primary productivity for the next several years as the semilabile DON perturbation was gradually removed via export.

  3. Modelling the vertical distribution of Prochlorococcus and Synechococcus in the North Pacific Subtropical Ocean.

    PubMed

    Rabouille, Sophie; Edwards, Christopher A; Zehr, Jonathan P

    2007-10-01

    A simple model was developed to examine the vertical distribution of Prochlorococcus and Synechococcus ecotypes in the water column, based on their adaptation to light intensity. Model simulations were compared with a 14-year time series of Prochlorococcus and Synechococcus cell abundances at Station ALOHA in the North Pacific Subtropical Gyre. Data were analysed to examine spatial and temporal patterns in abundances and their ranges of variability in the euphotic zone, the surface mixed layer and the layer in the euphotic zone but below the base of the mixed layer. Model simulations show that the apparent occupation of the whole euphotic zone by a genus can be the result of a co-occurrence of different ecotypes that segregate vertically. The segregation of ecotypes can result simply from differences in light response. A sensitivity analysis of the model, performed on the parameter alpha (initial slope of the light-response curve) and the DIN concentration in the upper water column, demonstrates that the model successfully reproduces the observed range of vertical distributions. Results support the idea that intermittent mixing events may have important ecological and geochemical impacts on the phytoplankton community at Station ALOHA. PMID:17803782

  4. What factors are driving summer phytoplankton blooms in the North Pacific Subtropical Gyre?

    NASA Astrophysics Data System (ADS)

    White, Angelicque E.; Spitz, Yvette H.; Letelier, Ricardo M.

    2007-12-01

    Annually recurrent summer to fall surface blooms of the dinitrogen (N2) fixing genera Trichodesmium and Richelia have a significant impact on biogeochemical cycling in the North Pacific Subtropical Gyre (NPSG). Yet the environmental determinants of these blooms have not been thoroughly resolved. Here, we combine remote sensing of ocean color, sea surface temperature (SST), sea surface height anomalies (SSHa), wind forcing, and integrated irradiance with the vessel-based time series of the Hawaii Ocean Time-series (HOT) program at Station ALOHA (22.75°N, 158.00°W) and mooring data derived from the National Data Buoy Center (NDBC) buoy 51001 (23.42°N, 162.2°W). With these data sets we attempt to constrain the environmental window under which blooms of large cell-sized N2 fixing organisms increase in abundance in NPSG surface waters using phycoerythrin (PE) as a proxy. For identified blooms, our analyses indicate that these events are confined to the months of June-October, SST in the range of 25°-27°C, and mixed layer depths less than 70 m. Neither wind forcing nor SSHa are correlated (directly or time-lagged) with increases in PE concentrations. Furthermore, blooms do not consistently result in increases of in situ or remotely sensed chlorophyll a. Additional higher-resolution data sets of physical forcing, diazotroph abundance, and biochemical properties, sampled on the timescale of bloom development (days-weeks), will be necessary to the environmental conditions supporting annual summer-fall blooms.

  5. 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.

  6. 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

  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. Bacterial dimethylsulfoniopropionate degradation genes in the oligotrophic north pacific subtropical gyre.

    PubMed

    Varaljay, Vanessa A; Gifford, Scott M; Wilson, Samuel T; Sharma, Shalabh; Karl, David M; Moran, Mary Ann

    2012-04-01

    Dimethylsulfoniopropionate (DMSP) is an organic sulfur compound that is rapidly metabolized by marine bacteria either by cleavage to dimethylsulfide (DMS) or demethylation to 3-methiolpropionate. The abundance and diversity of genes encoding bacterial DMS production (dddP) and demethylation (dmdA) were measured in the North Pacific subtropical gyre (NPSG) between May 2008 and February 2009 at Station ALOHA (22°45'N, 158°00'W) at two depths: 25 m and the deep chlorophyll maximum (DCM; ∼100 m). The highest abundance of dmdA genes was in May 2008 at 25 m, with ∼16.5% of cells harboring a gene in one of the eight subclades surveyed, while the highest abundance of dddP genes was in July 2008 at 25 m, with ∼2% of cells harboring a gene. The dmdA gene pool was consistently dominated by homologs from SAR11 subclades, which was supported by findings in metagenomic data sets derived from Station ALOHA. Expression of the SAR11 dmdA genes was low, with typical transcript:gene ratios between 1:350 and 1:1,400. The abundance of DMSP genes was statistically different between 25 m and the DCM and correlated with a number of environmental variables, including primary production, photosynthetically active radiation, particulate DMSP, and DMS concentrations. At 25 m, dddP abundance was positively correlated with pigments that are diagnostic of diatoms; at the DCM, dmdA abundance was positively correlated with temperature. Based on gene abundance, we hypothesize that SAR11 bacterioplankton dominate DMSP cycling in the oligotrophic NPSG, with lesser but consistent involvement of other members of the bacterioplankton community. PMID:22327587

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. Growth rates and production of heterotrophic bacteria and phytoplankton in the North Pacific subtropical gyre

    NASA Astrophysics Data System (ADS)

    Jones, David R.; Karl, David M.; Laws, Edward A.

    1996-10-01

    In field work conducted at 26°N, 155°W, in the North Pacific subtropical gyre, phytoplankton growth rates μp estimated from 14C labeling of chlorophyll a (chl a) averaged approximately one doubling per day in the euphotic zone (0-150 m). Microbial (microalgal plus heterotrophic bacterial) growth rates μm calculated from the incorporation of 3H-adenine into DNA were comparable to or exceeded phytoplankton growth rates at most depths in the euphotic zone. Photosynthetic rates averaged 727 mg C m -2 day -1 Phytoplankton carbon biomass, calculated from 14C labeling of chl a, averaged 7.2 mg m -3 in the euphotic zone. Vertical profiles of particulate DNA and ATP suggested that no more than 15% of particulate DNA was associated with actively growing cells. Heterotrophic bacterial carbon biomass was estimated from a two-year average at station ALOHA (22°45'N, 158°W) of flow cytometric counts of unpigmented, bacteria-size particles which bound DAPI on the assumption that 15% of the particles were actively growing cells and that heterotrophic bacterial cells contained 20 fg C cell -1 The heterotrophic bacterial carbon so calculated averaged 1.1 mg m -3 in the euphotic zone. Heterotrophic bacterial production was estimated to be 164 mg C m -2 day -1 or 23% of the calculated photosynthetic rate. Estimated heterotrophic bacterial growth rates averaged 0.97 day -1 in the euphotic zone and reached 4.7 day - at a depth of 20 m. Most heterotrophic bacterial production occurred in the upper 40 m of the euphotic zone, suggesting that direct excretion by phytoplankton, perhaps due to photorespiration or ultraviolet light effects, was a significant source of dissolved organic carbon for the bacteria.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

    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 15N/14N isotopic ratios (δ15N) 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, δ15N decreases between 1850 and the present. The total shift in δ15N of -2 per mil over this period is comparable to the total change in global mean sedimentary δ15N 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.

  16. 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

  17. Physical and biological controls of nitrate concentrations in the upper subtropical North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Ascani, François; Richards, Kelvin J.; Firing, Eric; Grant, Scott; Johnson, Kenneth S.; Jia, Yanli; Lukas, Roger; Karl, David M.

    2013-09-01

    Vertical profiles of nitrate down to 1000 m depth were obtained about every 5 days and over several years by four profiling floats deployed near Station ALOHA in the North Pacific subtropical gyre. As a first step, we study the episodic and rapid (10-30 days) changes in the depth of constant-nitrate surfaces observed in the float records. These changes are in general correlated with similar changes in the depth of isopycnal surfaces and have a small horizontal scale (horizontal wavelength less than 2°). They are furthermore observed over the whole water column sampled by the floats and throughout the year, with no apparent seasonal cycle. Using these characteristics as well as a 7-year high-resolution time series of potential density at Station ALOHA and a high-resolution numerical simulation of the circulation around the station, we conclude that these episodic changes correspond to the depth anomalies associated with the rapid changes and/or small-scale features of the eddy field. Large vertical velocities associated with submesoscale frontal processes are confined to the surface mixed layer (SML) and play no role in the episodic nitrate events except, perhaps, in late winter to early spring when the SML reaches the top of the nutricline. As a second step, we study the variations of nitrate concentration along isopycnal surfaces, which enables us to isolate the effects of biological processes. In the lower euphotic zone (125-200 m), the nitrate variations reflect the response of the ecosystem to the eddy variability: the shallower the isopycnal surface, the lower the nitrate concentration, and conversely, with nitrate varying in Redfield stoichiometric proportions with oxygen anomaly (defined here as dissolved oxygen minus oxygen saturation). In the upper euphotic zone (0-125 m), in contrast, eddy-induced variations in along-isopycnal oxygen anomaly do not conform with current knowledge about supply and variability of nitrate, ammonium and dissolved organic

  18. 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

  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. Interannual relationships between the tropical sea surface temperature and summertime subtropical anticyclone over the western North Pacific

    NASA Astrophysics Data System (ADS)

    Chung, Pei-Hsuan; Sui, Chung-Hsiung; Li, Tim

    2011-07-01

    The interannual variability of the Western North Pacific Subtropical High (WNPSH) in boreal summer is investigated with the use of the NCEP/NCAR Reanalysis Data. The most significant change of the 500 hPa geopotential height field appears at the western edge of the WNPSH, with dominant 2-3 year and 3-5 year power spectrum peaks. The 2-3 year oscillation of the WNPSH and associated circulation and sea surface temperature (SST) patterns possess a coherent eastward propagating feature, with a warm SST anomaly (SSTA) and anomalous ascending motion migrating from the tropical Indian Ocean in the preceding autumn to the maritime continent in the concurrent summer of a strong WNPSH. A strong WNPSH is characterized by anomalous anticyclonic circulation and maximum subsidence in the western North Pacific (WNP). The anomalous WNPSH circulation has an equivalent barotropic vertical structure and resides in the sinking branch of the local Hadley circulation, triggered by enhanced convection over the maritime continent. A heat budget analysis reveals that the WNPSH is maintained by radiative cooling. The 3-5 year oscillation of the WNPSH exhibits a quasi-stationary feature, with a warm SSTA (anomalous ascending motion) located in the equatorial central eastern Pacific and Indian Ocean and a cold SSTA (anomalous descending motion) located in the western Pacific. The anomaly pattern persists from the preceding winter to the concurrent summer of a high WNPSH. The greatest descent is located to the southeast of the anomalous anticyclone center, where a baroclinic vertical structure is identified. The zonal phase difference and the baroclinic vertical structure suggest that the anomalous anticyclone on this timescale is a Rossby wave response to a negative latent heating associated with the persistent local cold SSTA. ECHAM4 model experiments further confirm that the 2-3 year mode is driven by the SSTA forcing over the maritime continent, while the 3-5 year mode is driven by the

  1. The impact of meso-scale eddies on the Subtropical Mode Water in the western North Pacific

    NASA Astrophysics Data System (ADS)

    Liu, Cong; Li, Peiliang

    2013-06-01

    Based on the temperature and salinity from the Argo profiling floats and altimeter-derived geostrophic velocity anomaly (GVA) data in the western North Pacific during 2002-2011, the North Pacific Subtropical Mode Water (NPSTMW) distribution is investigated and cyclonic and anti-cyclonic eddies (CEs and AEs) are constructed to study the influence of their vertical structures on maintaining NPSTMW. Combining eddies identified by the GVA data and Argo profiling float data, it is found that the average NPSTMW thickness of AEs is about 60 dbar, which is thicker than that of CEs. The NPSTMW thicker than 150 dbar in AEs accounts for 18%, whereas that in CEs accounts for only 1%. About 3377 (3517) profiles, which located within one diameter of the nearest CEs (AEs) are used to construct the CE (AE). The composite AE traps low-PV water in the center and with a convex shape in the vertical section. The `trapped depth' of the composite CE (AE) is 300 m (550 m) where the rotational velocity exceeds the transitional velocity. The present study suggests that the anticyclonic eddies are not only likely to form larger amounts of NPSTMW, but also trap more NPSTMW than cyclonic eddies.

  2. 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.

  3. 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

  4. 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.

  5. Benthic community responses to pulses in pelagic food supply: North Pacific Subtropical Gyre

    NASA Astrophysics Data System (ADS)

    Smith, K. L.; Baldwin, R. J.; Karl, D. M.; Boetius, A.

    2002-06-01

    Time-series measurements of particulate organic carbon (POC) and particulate nitrogen (PN) fluxes, sediment community composition, and sediment community oxygen consumption (SCOC) were made at the Hawaii Ocean Time-series station (Sta. ALOHA, 4730 m depth) between December 1997 and January 1999. POC and PN fluxes, estimated from sediment trap collections made at 4000 m depth (730 m above bottom), peaked in late August and early September 1998. SCOC was measured in situ using a free vehicle grab respirometer that also recovered sediments for chemical and biological analyses on six cruises during the 1-year study. Surface sediment organic carbon, total nitrogen and phaeopigments significantly increased in September, corresponding to the pulses in particulate matter fluxes. Bacterial abundance in the surface sediment was highest in September with a subsurface high in November. Sediment macrofauna were numerically dominated by agglutinating Foraminifera fragments with highest density in September. Metazoan abundance, dominated by nematodes was also highest in September. SCOC significantly increased from a low in February to a high in September. POC and PN fluxes at 730 m above bottom were significantly correlated with SCOC with a lag time of ⩽14 days, linking pelagic food supply with benthic processes in the oligotrophic North Pacific gyre. The annual supply of POC into the abyss compared to the estimated annual demand by the sediment community (POC:SCOC) indicates that only 65% of the food demand is met by the supply of organic carbon.

  6. 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.

  7. GROWTH AND CARBON CONTENT OF THREE DIFFERENT-SIZED DIAZOTROPHIC CYANOBACTERIA OBSERVED IN THE SUBTROPICAL NORTH PACIFIC(1).

    PubMed

    Goebel, Nicole L; Edwards, Christopher A; Carter, Brandon J; Achilles, Katherine M; Zehr, Jonathan P

    2008-10-01

    To develop tools for modeling diazotrophic growth in the open ocean, we determined the maximum growth rate and carbon content for three diazotrophic cyanobacteria commonly observed at Station ALOHA (A Long-term Oligotrophic Habitat Assessment) in the subtropical North Pacific: filamentous nonheterocyst-forming Trichodesmium and unicellular Groups A and B. Growth-irradiance responses of Trichodesmium erythraeum Ehrenb. strain IMS101 and Crocosphaera watsonii J. Waterbury strain WH8501 were measured in the laboratory. No significant differences were detected between their fitted parameters (±CI) for maximum growth rate (0.51 ± 0.09 vs. 0.49 ± 0.17 d(-1) ), half-light saturation (73 ± 29 vs. 66 ± 37 μmol quanta · m(-2)  · s(-1) ), and photoinhibition (0 and 0.00043 ± 0.00087 [μmol quanta · m(-2)  · s(-1) ](-1) ). Maximum growth rates and carbon contents of Trichodesmium and Crocosphaera cultures conformed to published allometric relationships, demonstrating that these relationships apply to oceanic diazotrophic microorganisms. This agreement promoted the use of allometric models to approximate unknown parameters of maximum growth rate (0.77 d(-1) ) and carbon content (480 fg C · μm(-3) ) for the uncultivated, unicellular Group A cyanobacteria. The size of Group A was characterized from samples from the North Pacific Ocean using fluorescence-activated cell sorting and real-time quantitative PCR techniques. Knowledge of growth and carbon content properties of these organisms facilitates the incorporation of different types of cyanobacteria in modeling efforts aimed at assessing the relative importance of filamentous and unicellular diazotrophs to carbon and nitrogen cycling in the open ocean. PMID:27041718

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. Biogeochemical Evidence of Large Vertical Eddy Diffusivity Associated With Subtropical Mode Water of the North Pacific

    NASA Astrophysics Data System (ADS)

    Suga, T.; Sukigara, C.; Saino, T.; Toyama, K.; Yanagimoto, D.; Hanawa, K.; Shikama, N.; Ishizu, M.

    2008-12-01

    Based on the extensive profiling float observation carried out as part of the Kuroshio Extension System Study (KESS), Qiu et al. (2006) reported large vertical eddy diffusivity (2-5 x10-4 m2s-1) near the upper boundary of Subtropical Mode Water (STMW). This large diffusivity possibly have an impact on subsurface redistribution of heat, nutrients and dissolved gas components, etc., in the subtropical ocean. On the other hand, recent measurement of turbulent kinetic energy dissipation rate by Mori et al. (2008) indicates much smaller vertical eddy diffusivity (10-7 - 10-5 m2s-1) over the whole depth range of STMW. However, the direct comparison between the estimation by Qiu et al. and that by Mori et al. is possibly inappropriate because the former is based on the PV change over a couple of months and the latter on the instantaneous turbulent measurements. We carried out physical and biogeochemical observation to examine the vertical diffusivity near the top of STMW using a profiling float. The profiling float, which was equipped with a fluorometer and a dissolved oxygen sensor along with temperature and salinity sensors, was deployed in the STMW formation region and acquired quasi-Lagrangian, 5-day-interval time-series records from March to July in 2006. The time-series distribution of chl.a showed a sustained and sizable deep chlorophyll maximum just above the upper boundary of the STMW throughout early summer. Vertically integrated chlorophyll in this period was consistently ranging from 15-30 mgm-2, indicating sustained primary production and a continuous supply of nutrients ranging from 10-20 mgNm-2day-1. The time-series data indicate no sporadic events to supply nutrients and instead support, along with vertical profiles of nitrate obtained by ship-board measurements near the float, the large vertical diffusivity reported by Qiu et al. Since our estimation of vertical diffusivity is based on temporal evolution of primary production over several weeks, it is

  13. Does eddy-eddy interaction control surface phytoplankton distribution and carbon export in the North Pacific Subtropical Gyre?

    NASA Astrophysics Data System (ADS)

    Guidi, Lionel; Calil, Paulo H. R.; Duhamel, Solange; BjöRkman, Karin M.; Doney, Scott C.; Jackson, George A.; Li, Binglin; Church, Matthew J.; Tozzi, Sasha; Kolber, Zbigniew S.; Richards, Kelvin J.; Fong, Allison A.; Letelier, Ricardo M.; Gorsky, Gabriel; Stemmann, Lars; Karl, David M.

    2012-06-01

    In the North Pacific Subtropical Gyre (NPSG), the regular occurrence of summer phytoplankton blooms contributes to marine ecosystem productivity and the annual carbon export. The mechanisms underlying the formation, maintenance, and decay of these blooms remain largely unknown; nitrogen fixation, episodic vertical mixing of nutrients, and meso- (<100 km) and submesoscale (<10 km) physical processes are all hypothesized to contribute to bloom dynamics. In addition, zones of convergence in the ocean's surface layers are known to generate downwelling and/or converging currents that affect plankton distributions. It has been difficult to quantify the importance of these convergence zones in the export flux of particulate organic carbon (POC) in the open ocean. Here we use two high-resolution ocean transects across a pair of mesoscale eddies in the vicinity of Station ALOHA (22° 45'N, 158° 00'W) to show that horizontal turbulent stirring may have been a dominant control on the spatial distribution of the nitrogen fixing cyanobacteriumTrichodesmium spp. Fast repetition rate fluorometry measurements suggested that this distribution stimulated new primary production; this conclusion was not confirmed by 14C-based measurements, possibly because of different sampling scales for the two methods. Our observations of particle size distributions along the two transects showed that stretching by the mesoscale eddy field produced submesoscale features that mediated POC export via frontogenetically generated downwelling currents. This study highlights the need to combine high-resolution biogeochemical and physical data sets to understand the links betweenTrichodesmium spp. surface distribution and POC export in the NPSG at the submesoscale level.

  14. 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.

  15. Seasonal, interannual and decadal variations in particulate matter concentrations and composition in the subtropical North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Hebel, Dale V.; Karl, David M.

    The mean distributions of particulate carbon (PC), nitrogen (PN) and phosphorus (PP) in the euphotic zone (EZ) at Sta. ALOHA (22°45'N, 158°W) in the North Pacific Subtropical Gyre (NPSG) reveal a two-layered system with distinct upper (0-75 m) and lower (75-175 m) EZ dynamics. Particulate matter mean concentrations in the upper EZ were relatively constant with depth, and those in the lower EZ decreased significantly with increasing water depth. The vertical partitioning of particulate matter was approximately 60% in the upper EZ and 40% in the lower EZ. Significant temporal variability, both seasonal and interannual, was observed within both regions. PC and PN inventories in the upper EZ displayed a distinct annual cycle with variable interannual amplitude. The annual cycle was characterized by PC and PN maxima in summer and fall, and minima in winter. PP exhibited a smaller variation with season but also had a distinct wintertime minimum. These variations in particulate matter concentrations were accompanied by seasonal changes in elemental composition; summer and fall conditions were characterized by high C : P and N : P ratios exceeding 140 : 1 and 20 : 1, respectively. It is hypothesized that these concentration and composition patterns result from a net seasonal accumulation of non-living particulate matter throughout the summer and fall periods, and a rapid export during transition to winter conditions. Data also suggest that PN inventories in the NPSG have increased during the past three decades in response to changes in habitat, community composition or both. These temporally decoupled seasonal, interannual and decadal-scale ecological processes will complicate attempts to achieve mass balance or to derive mechanistic biogeochemical models.

  16. 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

  17. 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.

  18. 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.

  19. 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. PMID:19490029

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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

  6. 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

  7. North Pacific Acoustic Laboratory.

    PubMed

    Worcester, Peter F; Spindel, Robert C

    2005-03-01

    A series of long-range acoustic propagation experiments have been conducted in the North Pacific Ocean during the last 15 years using various combinations of low-frequency, wide-bandwidth transmitters and horizontal and vertical line array receivers, including a 2-dimensional array with a maximum vertical aperture of 1400 m and a horizontal aperture of 3600 m. These measurements were undertaken to further our understanding of the physics of low-frequency, broadband propagation and the effects of environmental variability on signal stability and coherence. In this volume some of the results are presented. In the present paper the central issues these experiments have addressed are briefly summarized. PMID:15810685

  8. 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.

  9. Identifying role of subtropical southeast Pacific SST anomalies on precipitation dynamics in Central Chile

    NASA Astrophysics Data System (ADS)

    Bozkurt, D.; Garreaud, R.

    2014-12-01

    Central Chile (CC, western South America coasts, 28°S- 38°S) is the heartland of Chile with the highest population and important economic activities. The region is characterized by semiarid Mediterranean climate with a marked precipitation gradient along the coast from north to south, mostly due to the positioning of the South Pacific Subtropical Anticyclone and the midlatitude westerlies belt. Although there are several diagnostic studies that focus on the impact of tropical Pacific SST on CC precipitation variability via atmospheric teleconnections, less attention has been placed on impacts of subtropical southeast (SE) Pacific SST on precipitation. The later region is immediately adjacent to CC and it interferes with the overpassing atmospheric systems. In particular we want to assess the impact of a consistent cooling over the SE Pacific during the last 30 years. This study is being tackled by a combination of observational and reanalysis datasets together with numerical simulations. Observational dataset includes gridded dataset of CRU, TRMM and GPCP. Moreover, Reynolds SST data V2 based on AVHRR infrared satellite SST data is used for analyzing spatial and temporal changes in SST. Current modelling experiment includes a control simulation, used as reference, and sensitivity simulation that involves perturbations to SST over subtropical SE Pacific for a normal year austral winter (2001) season. A number of simulations with different initial conditions have been carried out by employing ICTP-RegCM4. The domain for simulations was centered at 82oW and 32oW with 288x288 grid cells on 20 km spatial resolution. Preliminary results indicate that the response of precipitation in CC to SST anomalies in the subtropical SE Pacific exhibits more or less linear behavior. In the colder SST experiments, drier conditions dominate over CC, which is possibly related with the intensification of South Pacific Subtropical Anticyclone (SPSA) or a reduction in the available

  10. 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

  11. Comparative metagenomic analysis of a microbial community residing at a depth of 4,000 meters at station ALOHA in the North Pacific subtropical gyre.

    PubMed

    Konstantinidis, Konstantinos T; Braff, Jennifer; Karl, David M; DeLong, Edward F

    2009-08-01

    The deep sea (water depth of >2,000 m) represents the largest biome on Earth. Yet relatively little is known about its microbial community's structure, function, and adaptation to the cold and deep biosphere. To provide further genomic insights into deep-sea planktonic microbes, we sequenced a total of approximately 200 Mbp of a random whole-genome shotgun (WGS) library from a microbial community residing at a depth of 4,000 m at Station ALOHA in the Pacific Ocean and compared it to other available WGS sequence data from surface and deep waters. Our analyses indicated that the deep-sea lifestyle is likely facilitated by a collection of very subtle adaptations, as opposed to dramatic alterations of gene content or structure. These adaptations appear to include higher metabolic versatility and genomic plasticity to cope with the sparse and sporadic energy resources available, a preference for hydrophobic and smaller-volume amino acids in protein sequences, unique proteins not found in surface-dwelling species, and adaptations at the gene expression level. The deep-sea community is also characterized by a larger average genome size and a higher content of "selfish" genetic elements, such as transposases and prophages, whose propagation is apparently favored by more relaxed purifying (negative) selection in deeper waters. PMID:19542347

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. 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

  17. 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

  18. The subsurface water in the North Pacific tropical gyre

    NASA Astrophysics Data System (ADS)

    Wang, Fan; Li, Yuanlong; Zhang, Yanhui; Hu, Dunxin

    2013-05-01

    The subsurface water (22.5-25.5 σθ) in the North Pacific tropical gyre (NPTG; 130°E-150°W, 5°-10°N), addressed as the North Pacific tropical subsurface water (TSSW), features a lateral salinity minimum and vertical salinity maximum in the western and central Pacific Ocean. In this study this water body is investigated using Argo float profiles and Word Ocean Atlas 2009 (WOA09) dataset. Comparing with the North Pacific Tropical water (NPTW), the TSSW is of lower salinity, lower oxygen, higher nutrient concentration, and denser vertical salinity maximum Smax. Subtropical ventilation and local ocean dynamics are both important in setting up its unique characteristics. Our analysis shows that its properties, structure, and seasonal variations are diverse at different longitudes. In the western Pacific, the TSSW is mainly of North Pacific water origin. Its high salinity core is formed by the southward intrusion of the NPTW. Diapycnal mixing with the surface-layer fresh water reduces its salinity and lowers its Smax to denser isopycnals. The TSSW in the western Pacific can be regarded as a diluted portion of the NPTW. In the central Pacific, advection of salty water masses from both hemispheres and westward invasion of the eastern Pacific fresh water are all important in regulating its characteristics. The TSSW in the central Pacific is a mixture of various water sources formed under highly variable flow pattern and intensive mixing. The TSSW should be regarded as an important subsurface water body connecting North/South Pacific thermocline water, although it might not be a water mass by traditional definition.

  19. Silicon isotope fractionation during nutrient utilization in the North Pacific

    NASA Astrophysics Data System (ADS)

    Reynolds, Ben C.; Frank, M.; Halliday, A. N.

    2006-04-01

    The distribution of silicon in the North Pacific is controlled by the utilization of silicic acid by diatoms, a process that fractionates silicon (Si) isotopic compositions. Silicon isotope variations are presented for six water column profiles from the surface mixed layer down to the deep waters of the North Pacific Ocean. Although the observed Si isotopic variations display an apparently simple inverse relationship with dissolved nutrient concentrations, in fact they reflect mixing of surface waters undergoing active Si isotope fractionation and deep-waters with more uniform concentrations and isotope compositions. Samples from the surface of the subtropical gyre have the lowest dissolved Si concentrations and heaviest Si isotope compositions of marine waters measured thus far. Fractionation in the surface waters follows a typical Rayleigh-type distillation curve for a 'closed' surface water reservoir resulting from stratification of the surface layer in the subarctic region. In contrast, an 'open' system prevails within the subtropical gyre where there is significant recycling of silicic acid in the upper water column and lateral transport of silicon within surface currents. For deep waters, the Si isotope composition distinguishes between the northern North Pacific Deep Water (NPDW) and the southerly-derived bottom water. The relatively light Si isotope compositions measured from waters within the subarctic gyre provides evidence for isolation of the nutrient pool in the North Pacific.

  20. The pathway and circulation of North Pacific Intermediate Water

    NASA Astrophysics Data System (ADS)

    You, Yuzhu

    2003-12-01

    It has been speculated that the subtropical North Pacific Intermediate Water (NPIW) was formed by a shortcut of Okhotsk Sea source into the western subtropical gyre because this is the geographically shortest distance, and based on incomplete data. This mechanism is contradictory to the distribution of seawater properties, and, dynamically, is inconsistent with a basin-wide distribution of NPIW and associated gyre circulation. A lengthy transpacific pathway has been identified for the transformed NPIW source waters that first enter the eastern subtropical gyre, which is robust in a water-mass age distribution. Using an updated hydrography and a water-mass mixing scheme combining property distribution with flow streamfunction the present study establishes a dynamically self-consistent gyre circulation of NPIW and its pathway from the subpolar formation regions (source) to the Indonesian Throughflow (sink).

  1. 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.

  2. 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

  3. Wet Mercury Deposition to a Remote Islet (Pengjiayu) in the Subtropical Northwest Pacific Ocean in 2009-2013

    NASA Astrophysics Data System (ADS)

    Sheu, G. R.; Lin, N. H.

    2014-12-01

    One hundred and ninety-one weekly rainwater samples were collected between 2009 and 2013 at a weather station (25º37'46"N, 122º4'16.5"E, 101.7 m a.s.l.) in Pengjiayu, a remote islet in the subtropical Northwest (NW) Pacific Ocean with an area of 1.14 km2, to study the distribution of rainwater mercury (Hg) concentrations and associated wet deposition fluxes. This is likely one of the longest dataset 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 1.32 to 49.56 ng L-1, with an overall volume-weighted mean (VWM) concentration of 7.78 ng L-1. The annual VWM Hg concentrations were 8.85, 9.16, 7.08, 8.01 and 5.78 ng L-1 for 2009, 2010, 2011, 2012 and 2013, respectively. The annual wet Hg deposition fluxes were 13.54, 20.19, 10.84, 15.57 and 11.46 μg m-2, respectively, about 2.7-5 times the fluxes measured at sites on the Pacific coast of the USA and 1.5-2.8 times the flux measured in Bermuda, indicating higher wet Hg deposition to the NW Pacific Ocean than to the NE Pacific Ocean and the North Atlantic Ocean.

  4. 76 FR 58472 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-21

    ... National Oceanic and Atmospheric Administration RIN 0648-XA716 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ACTION: Notice of a public meeting of the North Pacific Fishery Management Council's (Council) Pacific Northwest Crab Industry Advisory Committee. SUMMARY: The Pacific...

  5. 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

  6. Mesoscale eddies in the NE Pacific tropical-subtropical zone.

    NASA Astrophysics Data System (ADS)

    Kurczyn, J. A.; Beier, E.; Lavín, M. F.; Chaigneau, A.

    2012-04-01

    Mesoscale eddy characteristics in the NE Pacific tropical-subtropical zone (16-30N) are analyzed using nearly 20 years of satellite altimetry maps and an automated eddy detection algorithm known as "the closed contours of sea-level anomaly (SLA)". The mean eddy characteristics of the study region are described based on the analysis of 1055 anticyclonic and 1097 cyclonic eddy trajectories. Eddies are preferentially formed near the coast in three main subregions: Punta Eugenia, Cabo San Lucas and Cabo Corrientes. The seasonally highest eddy generation occurs during spring in the three subregions, when surface winds are upwelling-favorable and strong upwelling events occur, thus promoting strong vertical shear between currents. Being highly non-linear and propagating toward the open ocean, mesoscale eddies can thus transport near-coastal seawater properties and plankton toward remote regions. In general, Punta Eugenia and Cabo San Lucas show the highest eddy occurrence. Long-lived eddies, having a life span greater than 16 weeks, are preferentially formed in Punta Eugenia. On average, eddy radii are larger than the Rossby internal radius of deformation, probably due to an up-scale energy cascade of geostrophic turbulence. Mean eddy propagation speeds in Cabo San Lucas and Punta Eugenia regions show higher values than the first baroclinic Rossby waves, while eddies south of ~19N travel slightly slower. The seasonal eddy generation and the eddy-prolific areas can be explained by the climatology of surface currents, where the eddy-prolific areas coincide with sites of strongest surface speeds, and the timing of the highest seasonal eddy generation corresponds with the strongest seasonal surface currents. Although relatively strong interannual variability is observed in terms of the local eddy activity index, no clear correlation is observed between eddy-generation events and large-scale climate indices such as the Pacific Decadal Oscillation index or the Multivariate

  7. 77 FR 29593 - North Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-18

    ... National Oceanic and Atmospheric Administration RIN 0648-XC027 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ACTION: Notice of public meetings. SUMMARY: The North Pacific Fishery Management... Harbor Convention Center, 236 Rezanof Drive, Kodiak, AK. Council address: North Pacific...

  8. 75 FR 1752 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-13

    ... National Oceanic and Atmospheric Administration RIN 0648-XT68 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ACTION: Notice of public meetings of the North Pacific Fishery Management Council Ecosystem Committee. SUMMARY: The North Pacific Fishery Management Council (Council)...

  9. 78 FR 4391 - North Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-22

    ... National Oceanic and Atmospheric Administration RIN 0648-XC447 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ACTION: Meetings of the North Pacific Fishery Management Council and its advisory committees. SUMMARY: The North Pacific Fishery Management Council (Council) and its...

  10. 77 FR 14350 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-09

    ... National Oceanic and Atmospheric Administration RIN 0648-XB072 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ACTION: Notice of meetings of the North Pacific Fishery Management Council Individual Fishing Quota (IFQ) Implementation Team. SUMMARY: The North Pacific Fishery Management...

  11. 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.

  12. Decadal variability of the Pacific Subtropical Cells and its relevance to the sea surface height in the western tropical Pacific during recent decades

    NASA Astrophysics Data System (ADS)

    Yamanaka, Goro; Tsujino, Hiroyuki; Nakano, Hideyuki; Hirabara, Mikitoshi

    2015-01-01

    variability of the Pacific Subtropical Cells (STCs) and associated sea surface height (SSH) in the western tropical Pacific during recent decades are examined by using an historical OGCM simulation. The model represents decadal variations of the STCs concurrent with tropical Pacific thermal anomalies: the eastern tropical Pacific is warmer when the STCs are weaker and cooler when they are stronger. The spatial patterns of the SSH in the western tropical Pacific show different features, depending on events associated with decadal variability. During the warm phase (1977-1987), the SSH anomalies exhibit deviations from a meridionally symmetric distribution, with weakly positive (strongly negative) anomalies in the western tropical North (South) Pacific. Analysis of the heat budget in the upper tropical Pacific indicates that the termination of the warm phase around 1985 results from a poleward heat transport anomaly that is induced by a horizontal gyre associated with the SSH anomalies. During the cold phase (1996-2006), in contrast, the SSH anomalies are nearly meridionally symmetric, with positive anomalies in both hemispheres. Enhanced easterly wind anomalies contribute to the development of the cold phase after the late 1990s.

  13. Massive icebergs & freshening of the subtropical North Atlantic

    NASA Astrophysics Data System (ADS)

    Hill, J. C.; Condron, A.

    2013-12-01

    New evidence from high-resolution seafloor bathymetry and a state-of-the-art numerical ocean circulation model shows that a significant amount of iceberg-laden meltwater flowed south from northern hemisphere ice sheets in a narrow coastal boundary current along the U.S. Atlantic margin, to the southern tip of Florida, following the Last Glacial Maximum (LGM). It is commonly assumed that meltwater would freshen the subpolar North Atlantic (50° - 70°N), but have little or no penetration to subtropical latitudes, south of 40°N. Using a combination of high-resolution multibeam bathymetry data and a state-of-the-art, high-resolution numerical ocean model, we are able to trace the pathway of icebergs and meltwater released from the Laurentide Ice Sheet (LIS) along the southern U.S. Atlantic margin. The bathymetry data show numerous well-defined relict iceberg scours from Cape Hatteras to the southern tip of Florida (~24.5°N) in water depths of 170 - 380 m, and are traceable for more than 30 km along the margin, suggesting that icebergs up to 300m thick reached these subtropical locations. The scour marks are oriented SSW along regional bathymetric contours and decrease in size and abundance moving south along the margin, concordant with increased iceberg melt as the distance from the ice calving margin increased. Our numerical model simulations confirm that iceberg laden meltwater can penetrate into the subtropical North Atlantic by flowing south, inshore of the Gulf Stream, as a narrow coastal boundary current that can significantly freshen this region and reduce the northward heat transport of the Gulf Stream. This evidence suggests a stronger influence of cold meltwater in the southern latitudes than previously recognized and highlights a distinct shift in paleocirculation patterns, including major adjustments in the Gulf Stream, since the LGM. Our findings strongly indicate that the freshening of the subtropical North Atlantic by icebergs and meltwater played an

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. 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.

  19. Subthermocline eddies observed by rapid-sampling Argo floats in the subtropical northwestern Pacific Ocean in Spring 2014

    NASA Astrophysics Data System (ADS)

    Zhang, Zhiwei; Li, Peiliang; Xu, Lixiao; Li, Cheng; Zhao, Wei; Tian, Jiwei; Qu, Tangdong

    2015-08-01

    In Spring 2014, two subthermocline eddies (STEs) were observed by rapid-sampling Argo floats in the subtropical northwestern Pacific (STNWP). The first one is a warm, salty, and oxygen-poor lens, with its temperature/salinity /dissolved oxygen (T/S/DO) anomalies reaching 1.16°C/0.21 practical salinity unit (psu)/-29.9 µmol/kg, respectively, near the 26.62σ0 surface. The other is a cold, fresh, and oxygen-rich lens, with its T/S/DO anomalies reaching -1.95°C/-0.34 psu/88.0 µmol/kg, respectively, near the 26.54σ0 surface. The vertical extent of the water mass anomalies in the warm (cold) STE is about 190 m (150 m), and its horizontal length scale is 22 ± 7 km (18 ± 10 km). According to their water mass properties, we speculate that the warm and cold STEs are generated in the North Pacific Subtropical and Subarctic Front region, respectively. The observed STEs may play an important role in modifying the intermediate-layer water properties in the STNWP, and this needs to be confirmed by more focused observations in the future.

  20. Spin-up of South Pacific Subtropical Gyre Freshens and Cools the Upper Layer of the Eastern South Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Schneider, W.; Fukasawa, M.; Garcés-Vargas, J.; Bravo, L.

    2007-05-01

    The general circulation in the South Pacific Ocean is dominated by the subtropical gyre, which manifests itself through elevated mean dynamic topography at its center. Gyre circulation consists of the westward South Equatorial Current, a narrow poleward western boundary current, the East Australian current, the eastward South Pacific Current streaming along the South Tropical Front (centered at around 40°S in the western ocean basin and at 30-35°S in the eastern basin), and the Humboldt Current System, a broad equatorward eastern boundary current, (in the literature, also referred to as the Peru/Chile Current) (Tomczak and Godfrey 1994; Levitus 1982; Reid 1986). The volume transport of upper water (700 m) between the Pacific coast of South America and the East Pacific Rise amounted to 18 Sv across 32.5°S (WOCE section P06) and 14 Sv across 17°S (WOCE section P21) (Tsimplis et al. 1998), emphasizing the importance of equatorward transport by this eastern boundary current system. This boundary current also plays a vital role in the fresh water budget by advecting fresher Subantarctic Surface Water northward thus forming Eastern South Pacific Transition Water (Emery and Meincke 1986). Here, temperature and salinity from the upper 200 m of the water column in the South Pacific Ocean were compared basin wide along 32°30'S between 2003 and 1992, based on two vertically and horizontally high resolution hydrographic repeat-sections involving 227 station pairs (WOCE, BEAGLE). Additionally, the seasonal cycles of the upper water column temperature and salinity between 90- 140°W and 30-35°S were established utilizing more than 1500 ARGO profiles from 2003 to 2006. The surface waters (0-200 m) of the eastern South Pacific Ocean, on average and seasonally adjusted, were clearly fresher in 2003 by 0.14 PSU. The seasonally adjusted, depth integrated temperature was 0.25°C colder in the same region. We further concluded a spin-up of the South Pacific subtropical gyre

  1. Geological history of the western North Pacific

    USGS Publications Warehouse

    Fischer, A.G.; Heezen, B.C.; Boyce, R.E.; Bukry, D.; Douglas, R.G.; Garrison, R.E.; Kling, S.A.; Krasheninnikov, V.; Lisitzin, A.P.; Pimm, A.C.

    1970-01-01

    A considerable portion of the abyssal floor of the western North Pacific was already receiving pelagic sediment in late Jurassic time. Carbonate sediments were later replaced by abyssal clays as the basin deepened and bottom waters became more aggressive. The resulting facies boundary, which can be recognized on seismic profiles, is broadly transgressive; it ranges in age from mid-Cretaceous in the western Pacific to Oligocene in the central Pacific. Cherts are encountered at and below the major facies boundary and appear to have been formed by postdepositional processes.

  2. 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...

  3. 77 FR 49781 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-17

    ... Lion Protection Measures EIS (77 FR 22750, April 17, 2012). Information on EIS development, potential... National Oceanic and Atmospheric Administration North Pacific Fishery Management Council; Public Meeting...), Commerce. ACTION: Notice of a public committee meeting. SUMMARY: The North Pacific Fishery...

  4. 78 FR 13867 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-01

    ... National Oceanic and Atmospheric Administration RIN 0648-XC524 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ACTION: Notice of public meetings. SUMMARY: The North Pacific Fishery Management Council (Council) Ecosystem Committee will meet by teleconference in Anchorage, AK. DATES:...

  5. 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...

  6. 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...

  7. SeaWiFS: North Pacific Storm

    NASA Technical Reports Server (NTRS)

    2002-01-01

    An extratropical storm can be seen swirling over the North Pacific just south of Alaska. This SeaWiFS image was collected yesterday at 23:20 GMT. Credit: Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  8. 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.

  9. 76 FR 23996 - North Pacific Fishery Management Council Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-29

    ... National Oceanic and Atmospheric Administration North Pacific Fishery Management Council Public Meeting ACTION: Notice of public meetings. SUMMARY: The North Pacific Fishery Management Council (Council) and.... Council address: North Pacific Fishery Management Council, 605 W. 4th Avenue, Suite 306, Anchorage,...

  10. 77 FR 67342 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-09

    ... National Oceanic and Atmospheric Administration RIN 0648-XC339 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ACTION: Notice of a public meeting. SUMMARY: The North Pacific Fishery.... Council address: North Pacific Fishery Management Council, 605 W. 4th Ave., Suite 306, Anchorage, AK...

  11. 78 FR 6811 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-31

    ... National Oceanic and Atmospheric Administration RIN 0648-XC472 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ACTION: Notice of a public meeting. SUMMARY: The North Pacific Fishery... Hall, 403 Marina Way, Kodiak, AK. Council address: North Pacific Fishery Management Council, 605 W....

  12. 76 FR 53416 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-26

    ... National Oceanic and Atmospheric Administration RIN 0648-XA667 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ACTION: Notice of a public meeting of the North Pacific Fishery Management.... Council address: North Pacific Fishery Management Council, 605 W. 4th Avenue, Suite 306, Anchorage,...

  13. 77 FR 56611 - North Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-13

    ... National Oceanic and Atmospheric Administration RIN 0648-XC230 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ACTION: Notice of public meetings. SUMMARY: The North Pacific Fishery Management... the Anchorage Hilton Hotel, 500 W. 3rd Avenue, Anchorage, AK. Council address: North Pacific...

  14. 77 FR 35359 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-13

    ... National Oceanic and Atmospheric Administration North Pacific Fishery Management Council; Public Meeting...), Commerce. ACTION: Notice of a public meeting. SUMMARY: The North Pacific Fishery Management Council's (Council) Golden King Crab Price Formula Committee is holding a meeting at the North Pacific...

  15. 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... Administration (NOAA), Commerce. ACTION: Notice of public meetings. SUMMARY: The North Pacific Fishery Management... address: North Pacific Fishery Management Council, 605 W. 4th Ave., Suite 306, Anchorage, AK...

  16. 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... Administration (NOAA), Commerce. ACTION: Notice of a public meeting. SUMMARY: The North Pacific Fishery..., Seattle, WA. Council address: North Pacific Fishery Management Council, 605 W. 4th Avenue, Suite...

  17. 78 FR 8110 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-05

    ... National Oceanic and Atmospheric Administration RIN 0648-XC483 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ACTION: Notice of a public workshop. SUMMARY: The North Pacific Fishery..., Birch/Willow room, 500 West 3rd Avenue, Anchorage, AK. Council address: North Pacific Fishery...

  18. 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....

  19. 77 FR 14351 - North Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-09

    ... 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 and its advisory committees. SUMMARY: The North Pacific Fishery Management Council (Council) and...

  20. 78 FR 15934 - North Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-13

    ... National Oceanic and Atmospheric Administration RIN 0648-XC557 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ACTION: Notice of public meetings. SUMMARY: The North Pacific Fishery Management.... Council address: North Pacific Fishery Management Council, 605 W. 4th Avenue, Suite 306, Anchorage,...

  1. 75 FR 2111 - North Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-14

    ... National Oceanic and Atmospheric Administration RIN 0648-XT73 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ACTION: Notice of public meetings. SUMMARY: The North Pacific Fishery Management... Benson Hotel, 309 SW Broadway, Portland, OR 97205. Council address: North Pacific Fishery...

  2. 75 FR 69632 - North Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-15

    ... National Oceanic and Atmospheric Administration RIN 0648-XA037 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ACTION: Notice of public meetings. SUMMARY: The North Pacific Fishery Management..., AK. Council address: North Pacific Fishery Management Council, 605 W. 4th Avenue, Suite...

  3. 76 FR 13360 - North Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-11

    ... National Oceanic and Atmospheric Administration RIN 0648-XA283 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ACTION: Notice of public meetings. SUMMARY: The North Pacific Fishery Management... Hotel, 500 West 3rd Avenue, Anchorage, AK. Council address: North Pacific Fishery Management...

  4. A Subtropical North Atlantic Regional Atmospheric Moisture Budget

    NASA Astrophysics Data System (ADS)

    Bingham, F.; D'Addezio, J. M.

    2014-12-01

    The synergistic effects of evaporation (E), precipitation (P), and Ekman transport make the SPURS (Salinity Processes in the Upper Ocean Regional Study) region in the subtropical North Atlantic (15-30°N, 30-45°W) the ideal location for the world's highest open ocean sea surface salinity. Using the MERRA and ERA-Interim atmospheric reanalyses, we reproduce the mean hydrologic state of the atmosphere over the SPURS region since 1979 and roughly deduce the change in salinity across the meridional domain due solely to interactions between E-P and Ekman transport. Our findings suggest a region that is highly evaporative at a mean rate of 4.87 mm/day with a standard deviation of 1.2 mm/day and little seasonality. Precipitation is much more variable with an annual fall maximum around 3 mm/day but only a mean rate of 1.37 mm/day with a standard deviation of 1.46 mm/day. The resulting E-P variable has a mean rate of 3.50 mm/day with a standard deviation of 1.92 mm/day and matches well with the moisture flux divergence term although the former is typically larger by a small margin. Strong prevailing easterly trade winds generate northward Ekman transports that advect water northward to the salinity maximum around 25°N. A short calculation shows that atmospheric moisture dynamics could potentially account for almost half of the change in salinity between 15°N and 25°N giving an estimate of the role that surface freshwater flux plays in the maintenance of the salinity maximum.

  5. A subtropical North Atlantic regional atmospheric moisture budget

    NASA Astrophysics Data System (ADS)

    D'Addezio, Joseph M.; Bingham, Frederick M.

    2014-12-01

    The synergistic effects of evaporation (E), precipitation (P), and Ekman transport make the Salinity Processes in the Upper Ocean Regional Study (SPURS-1) region in the subtropical North Atlantic (15-30°N, 30-45°W) the natural location for the world's highest open ocean SSS maximum. Using the MERRA and ERA-Interim atmospheric reanalyses, we reproduce the mean hydrologic state of the atmosphere over the SPURS-1 region since 1979 and roughly deduce the change in salinity across the meridional domain due solely to interactions between E-P and Ekman transport. Our findings suggest a region that is highly evaporative at a mean rate of 4.87 mm/d with a standard deviation of 1.2 mm/d and little seasonality. Precipitation is much more variable with an annual fall maximum around 3 mm/d but only a mean rate of 1.37 mm/d with a standard deviation of 1.46 mm/d. The resulting E-P variable has a mean rate of 3.50 mm/d with a standard deviation of 1.92 mm/d and matches well with the moisture flux divergence term although the former is typically larger by a small margin. Strong prevailing easterly trade winds generate northward Ekman transports that advect water toward the salinity maximum around 25°N. A short calculation shows that atmospheric moisture dynamics could potentially account for about one third of the change in salinity between 15°N and 25°N giving an estimate of the role that surface freshwater flux plays in the maintenance of the salinity maximum.

  6. Salinity Exchange through the Quasi-Stationary Jet from the Subtropical to the Subpolar Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Miyama, T.; Mitsudera, H.

    2014-12-01

    It is known that a quasi-stationary jet-like current [referred to as J1 in Isoguchi et al. (2006)] flows along the northern part of the Kuroshio/Oyashio mixed water region in the western Pacific Ocean. Observations (Isoguchi et al. 2006, Wagawa et al. 2014) have shown that the jet transports saline water in the subtropical Pacific Ocean to the subpolar region. To investigate how the subtropical water is transported through the quasi-stationary jet, numerical particle were tracked using a high resolution ocean reanalysis dataset, the Japan Coastal Ocean Predictability Experiment (JCOPE2). Particle released from the region near the quasi-stationary jet (152-158°E, 42-45°N) are tracked for one year from 15th day of every month and every year (1993-2013) with daily velocity of the JCOPE2 reanalysis at 30 m depth. Backward particle tracking shows that the particles near the jet come from wide southward area, which suggests that eddies are important in the transport process of the saline subtropical water. The number of particles that go back to the region south of 36°N within one year varies greatly in time, from 0.002% to 20% of the total particles. Forward particle tracking shows that the part of particles flows northeastward, which indicates the western subpolar gyre, while part of the particles are trapped in another jet-like current [referred to as J2 in Isoguchi et al. (2006)].

  7. 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.

  8. 75 FR 11134 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-10

    ... National Oceanic and Atmospheric Administration RIN 0648-XU98 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ] ACTION: Notice of a public meeting of the North Pacific Fishery Management... Pacific Fishery Management Council, 605 W. 4th Avenue, Suite 306, Anchorage, AK 99501-2252. FOR...

  9. 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.

  10. 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

  11. 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

  12. 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.

  13. 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

  14. 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

  15. 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.

  16. Characterizations of wet mercury deposition to a remote islet (Pengjiayu) in the subtropical Northwest Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Sheu, Guey-Rong; Lin, Neng-Huei

    2013-10-01

    Thirty-four weekly rainwater samples were collected in 2009 at Pengjiayu, a remote islet in the subtropical Northwest (NW) Pacific Ocean, 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 Hg0 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 Hg0 emissions could be transported to the upper troposphere or marine boundary layer (MBL) where they can be oxidized to produce RGM, which will then be effectively scavenged by cloud water and rainwater.

  17. 77 FR 12814 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-02

    ... National Oceanic and Atmospheric Administration RIN 0648-XB055 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ACTION: Notice of a meeting of the North Pacific Fishery Management Council (Council) and Alaska Board of Fisheries (AK BOF) Joint Protocol Committee. SUMMARY: The North...

  18. 76 FR 22677 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-22

    ... National Oceanic and Atmospheric Administration RIN 0648-XA388 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ACTION: Notice of a public meeting. SUMMARY: The North Pacific Fishery... Science Center (AFSC), Traynor Room, 7600 Sand Point Way NE., Seattle, WA. Council address: North...

  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. 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.

  1. 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

  2. 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.

  3. 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.

  4. Ocean salinity changes in the northwest Pacific subtropical gyre: The quasi-decadal oscillation and the freshening trend

    NASA Astrophysics Data System (ADS)

    Nan, Feng; Yu, Fei; Xue, Huijie; Wang, Ran; Si, Guangcheng

    2015-03-01

    Ocean salinity changes play an important role in modulating ocean and climate variability. Analyses of the repeating observations along PN, TK, and 137°E sections reveal that both surface and subsurface salinity in the Northwest Pacific Subtropical Gyre (NPSG) had clear quasi-decadal oscillation (QDO) of ˜10 year and a sustained freshening trend during 1987-2012. Surface salinity in the NPSG troughed in 1989, 1999, and 2008, and peaked in 1993, and 2003. The peak-to-tough range of surface salinity oscillation can reach 0.3 psu. Meanwhile, surface salinity decreased about 0.10 psu from 1987 to 2012 with a freshening trend of -0.0042 psu yr-1. These surface salinity anomalies were subducted into the subsurface layer mainly in the ventilated zone along the Kuroshio Extension, and advected over the NPSG. The QDO of the subsurface salinity maximum (Smax) lagged that of the surface salinity by about 1˜2 years. Both the peak-to-tough range of the Smax oscillation (0.15 psu) and its freshening trend (-0.0036 psu yr-1) are smaller than those of the surface salinity. Salinity changes in the NPSG likely began in the mid-1970s associated with the North Pacific regime shift during 1976/1977. Analyses of mixed layer salinity budget indicated that air-sea freshwater flux change in the NPSG is the leading factor controlling the surface salinity anomalies, while change of large-scale ocean circulation (Geostrophic advection) also plays a minor role. Salinity and air-sea freshwater flux changes in the NPSG are all closely related to the Pacific Decadal Oscillation, indicating the large-scale ocean-atmosphere interaction.

  5. 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.

  6. Superoxide production and decay in the subtropical North Pacific

    NASA Astrophysics Data System (ADS)

    Roe, K.; Voelker, B. M.; Hansel, C. M.

    2012-12-01

    Reactive oxygen species (ROS), which include superoxide and hydrogen peroxide, can be generated through photochemical reactions or biological activity in seawater. The generation of ROS, especially superoxide, by photochemical or biological processes can influence trace metal speciation and cycling in the ocean since superoxide can react quickly with metals (Cu and Fe) and is capable of both oxidation and reduction of trace metals. In this study superoxide was detected and measured in the oligotrophic waters at station ALOHA by a MCLA chemiluminescence flow injection method. The superoxide concentrations ranged between 0.037-0.099 nM, had observed decay rates of 0.004-0.014 s-1, and production rates of 0.88-4.81 nM hr-1 during a 16 day period during July 2012. The influence of biological activity vs photochemical production on superoxide concentration, decay and production rates are discussed.

  7. 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.

  8. 77 FR 38773 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-29

    ... meeting will occur during the scoping period for the Steller Sea Lion Protection Measures EIS (77 FR 22750... National Oceanic and Atmospheric Administration North Pacific Fishery Management Council; Public Meeting...), Commerce. ACTION: Notice of committee meeting. SUMMARY: The North Pacific Fishery Management...

  9. 78 FR 29116 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-17

    ... National Oceanic and Atmospheric Administration RIN 0648-XC679 North Pacific Fishery Management Council... Administration (NOAA), Commerce. ACTION: Meeting of the North Pacific Fishery Management Council (Council) and... Management Council Joint Protocol ] Committee of the AK B0F and Council will meet in Juneau, AK. DATES:...

  10. 78 FR 13867 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-01

    ... National Oceanic and Atmospheric Administration RIN 0648-XC530 North Pacific Fishery Management Council... Management Council's (Council) Steller Sea Lion Mitigation Committee (SSLMC) will meet in Anchorage, AK..., Anchorage, AK. Council address: North Pacific Fishery Management Council, 605 W. 4th Ave., Suite...

  11. Impact of the winter North-Atlantic weather regimes on subtropical sea-surface height variability

    NASA Astrophysics Data System (ADS)

    Barrier, Nicolas; Treguier, Anne-Marie; Cassou, Christophe; Deshayes, Julie

    2013-09-01

    Interannual variability of subtropical sea-surface-height (SSH) anomalies, estimated by satellite and tide-gauge data, is investigated in relation to wintertime daily North-Atlantic weather regimes. Sea-level anomalies can be viewed as proxies for the subtropical gyre intensity because of the intrinsic baroclinic structure of the circulation. Our results show that the strongest correlation between SSH and weather regimes is found with the so-called Atlantic-Ridge (AR) while no significant values are obtained for the other regimes, including those related to the North Atlantic Oscillation (NAO), known as the primary actor of the Atlantic dynamics. Wintertime AR events are characterized by anticyclonic wind anomalies off Europe leading to a northward shift of the climatological wind-stress curl. The latter affects subtropical SSH annual variability by altered Sverdrup balance and ocean Rossby wave dynamics propagating westward from the African coast towards the Caribbean. The use of a simple linear planetary geostrophic model allows to quantify those effects and confirms the primary importance of the winter season to explain the largest part of SSH interannual variability in the Atlantic subtropical gyre. Our results open new perspectives in the comprehension of North-Atlantic Ocean variability emphasizing the role of AR as a driver of interannual variability at least of comparable importance to NAO.

  12. 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

  13. Fishery-induced changes in the subtropical Pacific pelagic ecosystem size structure: observations and theory.

    PubMed

    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

  14. 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.

  15. 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

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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

  1. An oceanic mechanism for decadal variability in the North Pacific

    NASA Astrophysics Data System (ADS)

    Dawson, Andrew; Stevens, David; Matthews, Adrian

    2013-04-01

    Many studies have noted decadal scale sea surface temperature (SST) variability in the North Pacific Ocean. The spatial SST pattern has a cold anomaly in the central North Pacific that extends to the Pacific western boundary and resembles a broader and weaker El Nino signal in the tropics. This pattern of variability is often referred to as the Pacific Decadal Oscillation (PDO). Despite extensive research, the nature of the apparent oscillation between warm and cold SST anomalies in the central North Pacific is still surrounded by much uncertainty. A generally agreed upon point is that decadal-scale SST variability appears to be somehow linked to El Nino. However, the mechanism by which such variability is generated, be it an independent dynamical process or a stochastic reddening of other climate signals, is not well understood. Decadal variability in the North Pacific has impacts both locally and remotely. Temperature changes in the North Pacific can have a significant effect on the local ecosystem. Remote effects of the PDO include changes to the surface climate (e.g., temperature and precipitation) in Australia, South and North America, the Russian Far East, much of eastern Asia, and the maritime continent. Improved understanding of decadal variability in the North Pacific could lead to a better understanding of climate variability in these remote regions. Here we use a state-of-the-art high-resolution coupled climate model, HiGEM, to show that anomalous ocean transport in the North Pacific can largely account for the decadal-scale SST variability. We also demonstrate that it is likely that the same mechanism occurs in the real ocean, and therefore that internal ocean dynamics play a key role in regulating decadal-scale variability in the North Pacific.

  2. Mesoscale contribution to salinity transport in the North Atlantic subtropics (2011-2013)

    NASA Astrophysics Data System (ADS)

    Reverdin, Gilles; Boutin, Jacqueline; Centurioni, Luca; Hormann, Verena; Kolodziejczyk, Nicolas; Font, Jordi; Salvador, Joaquin; Sommer, Anna; Martin, Nicolas; Morisset, Simon

    2014-05-01

    Mesoscale activity is expected to contribute to transport salt horizontally out of the region of maximum salinity of the North Atlantic subtropical gyre. Using in situ and satellite observations, we investigate the contribution of mesoscale activity to the salinity budget in the central part of the subtropical gyre. Surface current data originate from close to 150 surface drifters deployed for SPURS, as well as satellite altimetry from Aviso products, and salinity data originate mostly from Argo floats, over 100 drifters and thermosalinographs, in particular from the SSS observing system ships Coriolis and Toucan (www.legos.obs-mip.fr/fr/soa/ore-sss/distribution). The period investigated is from 2011 to 2013. Near 30°N, north of the subtropics, as well as near 20°N, SMOS data indicate significant meridional transport, despite the large noise on the data, and the filtering of the smaller scales (100 km) of the transport. Closer to the core of the subtropical gyre, we find evidence in the drifter data of significant meridional transport, but that is highly irregular in time, as it seems associated with a few specific events. Whether this is due to the inhomogneous and Lagrangian nature of the sampling is discussed. We also check the budget at a smaller spatial scale using a dedicated meso-scale cruise (Strasse) in August 2012.

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

    NASA Astrophysics Data System (ADS)

    Huang, Yanyan; Li, Xiaofan; Wang, Huijun

    2015-10-01

    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.

  4. 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.

  5. 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.

  6. NO2 seasonal evolution in the north subtropical free troposphere

    NASA Astrophysics Data System (ADS)

    Gil-Ojeda, M.; Navarro-Comas, M.; Gómez-Martín, L.; Adame, J. A.; Saiz-Lopez, A.; Cuevas, C. A.; González, Y.; Puentedura, O.; Cuevas, E.; Lamarque, J.-F.; Kinninson, D.; Tilmes, S.

    2015-09-01

    Three years of multi-axis differential optical absorption spectroscopy (MAXDOAS) measurements (2011-2013) have been used for estimating the NO2 mixing ratio along a horizontal line of sight from the high mountain subtropical observatory of Izaña, at 2370 m a.s.l. (NDACC station, 28.3° N, 16.5° W). The method is based on horizontal path calculation from the O2-O2 collisional complex at the 477 nm absorption band which is measured simultaneously to the NO2 column density, and is applicable under low aerosol-loading conditions. The MAXDOAS technique, applied in horizontal mode in the free troposphere, minimizes the impact of the NO2 contamination resulting from the arrival of marine boundary layer (MBL) air masses from thermally forced upwelling breeze during middle hours of the day. Comparisons with in situ observations show that during most of the measuring period, the MAXDOAS is insensitive or very slightly sensitive to the upwelling breeze. Exceptions are found for pollution events during southern wind conditions. On these occasions, evidence of fast, efficient and irreversible transport from the surface to the free troposphere is found. Background NO2 volume mixing ratio (vmr), representative of the remote free troposphere, is in the range of 20-45 pptv. The observed seasonal evolution shows an annual wave where the peak is in phase with the solar radiation. Model simulations with the chemistry-climate CAM-Chem model are in good agreement with the NO2 measurements, and are used to further investigate the possible drivers of the NO2 seasonality observed at Izaña.

  7. Fluctuating sea surface temperatures in the subtropical North Atlantic during Oceanic Anoxic Event 1a at DSDP Site 398 and ODP Site 641

    NASA Astrophysics Data System (ADS)

    Hofmann, P.; Wiegand, R.; Handley, L.; Wagner, T.; Talbot, H. M.; Mcanena, A.

    2012-04-01

    The early Aptian is characterized by a perturbation of the global carbon cycle which occurred during Oceanic Anoxic Event 1a (OAE 1a, Selli-Event, ca. 120 Ma). OAE 1a is well documented by organic carbon-rich sediments from marine and terrestrial localities worldwide. The trigger mechanism and the environmental consequences of OAE 1a are still under dispute. Here we present sea surface temperature estimates based on TEX 86 measurements (tetraether index of tetraethers containing 86 carbons) from the Galicia Margin (subtropical North Atlantic) at DSDP Site 398 and ODP Site 641C. The investigated sites are approximately 350 km apart and located on the slope of the Vigo seamount (Site 398) and the Galicia Bank (Site 641). Sea surface temperature (SST) records at both Sites suggest a significant and sustained warming of the Galica Margin surface waters during OAE 1a. The observed warming during OAE 1a is disrupted by several SST decreases which vary in magnitude from site to site. Similar surface water cooling episodes but with different magnitudes have been reported from the central Pacific region. The exact nature and timing of these intermittent cooling periods remains to be discovered but the occurrence in both the North Atlantic and Pacific may point towards a global trigger mechanism. We speculate that the thermal development of the surface waters of the subtropical North Atlantic during OAE 1a may reflect global fluctuations in pCO2 in response to variations in the intensity of Pacific volcanic activity in the Pacific Ontong Java area with superimposed local adjustments in the oceanic circulation pattern of the North Atlantic.

  8. 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.

  9. Response of the subtropical North Atlantic surface hydrography on deglacial and Holocene AMOC changes

    NASA Astrophysics Data System (ADS)

    Repschläger, Janne; Weinelt, Mara; Kinkel, Hanno; Andersen, Nils; Garbe-Schönberg, Dieter; Schwab, Christian

    2015-05-01

    The North Atlantic subtropical gyre (STG) circulates warm waters between 10 and 40°N and is a potential area of heat storage during periods of reduced North Atlantic Meridional Overturning Circulation (AMOC), when warm salt-rich waters are retained in the subtropics. In this study, we investigated multicentennial to millennial scale changes in subtropical North Atlantic hydrography in response to AMOC changes during the last deglaciation and early Holocene, using sediment cores MD08-3180 and GEOFAR KF16. The coring site (38°N) is situated near the boundary between transitional eastern North Atlantic waters and STG waters that is formed by the Azores Front. Hydrographic changes are reconstructed using new stable isotope data of benthic and subsurface dwelling planktonic foraminifera, Mg/Ca measurements on planktonic foraminifera, and planktonic foraminifera abundances that are supplemented with published sea surface temperature and stable isotope data. These multiproxy data indicate a close coupling between the latitudinal position of the northern STG boundary and deglacial AMOC modes. During weak AMOC phases (Heinrich event 1, Younger Dryas (YD), 8.2 ka event), Northern Hemisphere subpolar water reached down to the northern STG boundary, displacing the boundary southward. During the Bølling-Allerød warm period, a strong warming trend of the subtropical region to 19°C is observed. A cooling of the sea surface temperature by 6°C during the YD is accompanied by ongoing northward transport of warm subsurface water that might have contributed to the restart of AMOC.

  10. 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

  11. 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.

  12. 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.

  13. Assemblages of phytoplankton pigments along a shipping line through the North Atlantic and tropical Pacific

    NASA Astrophysics Data System (ADS)

    Dandonneau, Yves; Niang, Awa

    2007-05-01

    A set of phytoplankton pigment measurements collected on eight quarterly transects from France to New Caledonia is analyzed in order to identify the main assemblages of phytoplankton and to relate their occurrence to oceanic conditions. Pigment concentrations are first divided by the sum [monovinyl chlorophyll a plus divinyl chlorophyll a] to remove the effect of biomass, and second are normalized to give an equal weight to all pigments. The resulting 17 pigments × 799 observations matrix is then classified into 10 clusters using neural methodology. Eight out of these 10 clusters have a well marked regional or seasonal character, thus evidencing adapted responses of the phytoplankton communities. The main gradient opposes two clusters with high fucoxanthin and chlorophyll c1+2 in the North Atlantic in January, April and July, to three clusters in the South Pacific Subtropical Gyre with high divinyl chlorophyll a, zeaxanthin and phycoerythrin. One of the clusters in the South Pacific Subtropical Gyre has relatively high zeaxanthin and phycoerythrin contents and dominates in November and February (austral summer), while another with relatively high divinyl chlorophylls a and b dominates in May and August (austral winter). The third one in the South Pacific is characterized by high carotene concentration and its occurrence peaks in February and May. In the equatorial current system, one cluster, rich in chlorophylls b and c1+2, is strictly located in a narrow zone centred at the equator, while another with relatively high violaxanthin concentration is restricted to the high nutrient - low chlorophyll waters in only the southern part of the South Equatorial Current. One cluster with relatively high prasinoxanthin content has a spatial distribution spanning the entire South Equatorial Current. Two clusters have a ubiquitous distribution: one in the equatorial Pacific, the Carribbean Sea and the North Atlantic during summer has pigment concentrations close to the

  14. 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.

  15. 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.

  16. 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.

  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

    2016-01-01

    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. PMID:26915424

  18. 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.

  19. 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

  20. 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...

  1. 76 FR 71321 - North Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-17

    ... Anchorage Hilton Hotel. DATES: The Council will begin its plenary session at 8 a.m. on Wednesday, December 7... Hilton Hotel, 500 West Third Avenue, Anchorage, AK. Council address: North Pacific Fishery...

  2. 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

  3. 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.

  4. 76 FR 22081 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-20

    ... National Oceanic and Atmospheric Administration RIN 0648-XA380 North Pacific Fishery Management Council... Fishery Management Council's (NPFMC) Crab Plan Team (CPT) will meet in Juneau, AK. DATES: The meeting will... Pacific Fishery Management Council, 605 W. 4th Avenue, Suite 306, Anchorage, AK 99501-2252. FOR...

  5. 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...

  6. 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.

  7. 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. PMID:22873743

  8. 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.

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

    PubMed Central

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

    2015-01-01

    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

  10. 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

  11. 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., Jr.; 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

  12. The impact of South Pacific extratropical forcing on ENSO and comparisons with the North Pacific

    NASA Astrophysics Data System (ADS)

    Ding, Ruiqiang; Li, Jianping; Tseng, Yu-heng

    2015-04-01

    Previous studies suggest that North Pacific extratropical atmospheric variability influences ENSO via the seasonal footprinting mechanism (SFM). This study confirms that quadrapole sea surface temperature (SST) variability in the extratropical South Pacific triggered by mid-latitude South Pacific atmospheric variability may also have an additional influence on ENSO. The response of the evolution of the ENSO-related zonal wind and SST anomalies in the tropics to the South Pacific extratropical forcing is consistent with the SFM hypothesis. That is, the Pacific-South American (PSA) pattern of the South Pacific extratropical sea level pressure (SLP) anomalies imparts an SST footprint (i.e., a quadrapole SST pattern) onto the ocean during austral summer. This SST footprint subsequently forces the zonal wind anomalies along the equator in the following austral winter that ultimately result in ENSO events during the following austral summer via ocean-atmosphere coupling in the tropics. The present study demonstrates that the influences of extratropical atmospheric variability in the South Pacific and North Pacific on ENSO are different and relatively independent. It is possible that they may, together or separately, influence the occurrence of ENSO events, and the importance of the South Pacific forcing in initiating ENSO events is comparable with that of the North Pacific forcing. An empirical model was established to predict the Niño3.4 index based on the combined South Pacific and North Pacific signals, and results show that it can be used to produce skillful forecasts of the Niño3.4 index with a leading time of up to 1 year.

  13. 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

  14. North Pacific climate variability and Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Linkin, Megan E.

    Boreal winter North Pacific climate variability strongly influences North American hydroclimate and Arctic sea ice distribution in the marginal Arctic seas. Two modes of atmospheric variability explaining 53% of the variance in the Pacific Ocean sea level pressure (SLP) field are extracted and identified: the Pacific-North American (PNA) teleconnection and the North Pacific Oscillation/West Pacific (NPO/WP) teleconnection. The NPO/WP, a dipole in North Pacific SLP and geopotential heights, is affiliated with latitudinal displacements of the Asian Pacific jet and an intensification of the Pacific stormtrack. The North American hydroclimate impacts of the NPO/WP are substantial; its impact on Alaska, Pacific Northwest and Great Plains precipitation is more influential than both the PNA and the El Nino-Southern Oscillation (ENSO). The NPO/WP is also strongly associated with a contemporaneous extension of the marginal ice zone (MIZ) in the western Bering Sea and Sea of Okhotsk and MIZ retreat in the eastern Bering Sea. Wintertime climate variability also significantly impacts the distribution of Arctic sea ice during the subsequent summer months, due to the hysteretic nature of the ice cap. The North Atlantic Oscillation (NAO) is known for its effects on summer sea ice distribution; this study extends into the Pacific and finds that circulation anomalies related to Pacific sea surface temperature (SST) variability also strongly impact summer Arctic sea ice. The NAO and ENSO are related to sea ice decline in the Eastern Siberian Sea, where the linear trend since 1979 is 25% per decade. PDV affects sea ice in the eastern Arctic, a region which displays no linear trend since 1979. The low frequency of PDV variability and the persistent positive NAO during the 1980s and 1990s results in natural variability being aliased into the total linear trend in summer sea ice calculated from satellite-based sea ice concentration. Since 1979, natural variability accounts for 30% of

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Variability in the Correlation between Asian Dust Storms and Chlorophyll a Concentration from the North to Equatorial Pacific

    PubMed Central

    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

  20. 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

  1. The Latitudinal and Vertical Thermal Distribution Change from the Last Glacial Maximum in the Western North Pacific

    NASA Astrophysics Data System (ADS)

    Sagawa, T.; Murayama, M.; Ikehara, M.; Okamura, K.; Oba, T.

    2008-12-01

    We conducted multi-species analysis of planktonic foraminiferal oxygen isotope and Mg/Ca in the tropical and subtropical western North Pacific sediment core in order to investigate latitudinal and vertical thermal structure change from the LGM. A box core 3cBX was collected from the west Caroline Basin (8 01 N, 139 38 E), and a piston core ASM5 was collected from the Amami Sea Mount (28 23 N, 132 45 E). Eight and seven species of planktonic foraminifera were picked from 3cBX and ASM5, respectively, in order to analyze oxygen isotope. In the tropics, the glacial-interglacial amplitude of G. ruber oxygen isotope was approximately 1.0 per mil between LGM and Holocene. On the other hand, the amplitude in the subtropics was approximately 1.5per mil. Because G. ruber prefers summer warmest temperature, the oxygen isotope difference suggested that the latitudinal summer surface temperature/salinity gradient in the last glacial period was steeper than that of modern. Multi-species approach reveals that the vertical thermal structure variations in the North Pacific. The vertical thermal gradient in the subtropic region was gentler in the LGM and steeper in the last deglaciation than modern condition. We will discuss about Mg/Ca temperature and salinity variation in the presentation.

  2. 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

  3. High-resolution migration history of the Subtropical High/Trade Wind system of the northeastern Pacific during the last ~55 years: Implications for glacial atmospheric reorganization

    NASA Astrophysics Data System (ADS)

    Cheshire, Heather; Thurow, Juergen

    2013-06-01

    Guaymas Basin, Gulf of California, is a restricted basin located under the present-day wet/dry subtropical divide (~27°N) and is ideally circumstanced for detecting variations in the North Pacific Subtropical High (NPSH)/Trade Wind system. Controlled by climate cell boundary displacement, NPSH midwinter location was the primary influence on timing and intensity of upwelling seasons in Guaymas Basin. Analysis of high-resolution X-ray fluoresence data and sediment fabric log from 75% laminated Core MD02-2517/2515, western Guaymas Basin, reveals systematic changes in NPSH behavior over the last ~55 kyr BP. Southward displacement of the wet/dry subtropical divide controlled upwelling-related diatom productivity, while sea level and regional rainfall controlled terrigenous supply. The basin was oxic during the glacial, and preservation was ensured by high burial rate due to the increased deposition of terrigenous sediment. Sediment fabric style (number and/or thickness of laminae, plus color banding and homogeneous intervals) changes systematically through the core and gives insights into the number of seasons occurring in Guaymas Basin, and the occurrence and intensity of the upwelling season. Five millennial-scale low flux events with close timing to Heinrich events and ten decadal/centennial-scale low biogenic silica events occurring in the interval ~33-16.5000 years Before Present (kyr BP) are interpreted as times of extreme aridity. At ~16.5 kyr BP, a regime shift from terrigenous-dominated oxic to evenly balanced biogenic-terrigenous dysoxic conditions occurred. Although there was a further extreme arid event at ~11.5 kyr BP, ~16.5 kyr BP was essentially the beginning of the interglacial.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Simulation and Prediction of North Pacific Sea Surface Temperature

    NASA Astrophysics Data System (ADS)

    Lienert, Fabian

    The first part of this thesis is an assessment of the ability of global climate models to reproduce observed features of the leading Empirical Orthogonal Function (EOF) mode of North Pacific sea surface temperature (SST) anomalies known as the Pacific Decadal Oscillation (PDO). My results are that 1) the models as group produce a realistic pattern of the PDO. The simulated variance of the PDO index is overestimated by roughly 30%. 2) The tropical influence on North Pacific SSTs is biased systematically in these models. The simulated response to El Nino-Southern Oscillation (ENSO) forcing is delayed compared to the observed response. This tendency is consistent with model biases toward deeper oceanic mixed layers in winter and spring and weaker air-sea feedbacks in the winter half-year. Model biases in mixed layer depths and air-sea feedbacks are also associated with a model mean ENSO-related signal in the North Pacific whose amplitude is overestimated by roughly 30%. Finally, model power spectra of the PDO signal and its ENSO-forced component are "redder" than observed due to errors originating in the tropics and extratropics. 3) The models are quite successful at capturing the influence of both the tropical Pacific related and the extratropical part of the PDO on North American surface temperature. 4) The models capture some of the influence of the PDO on North American precipitation mainly due to its tropical Pacific related part. In the second part of this thesis, I investigate the ability of one such coupled ocean-atmosphere climate model, carefully initialized with observations, to dynamically predict the future evolution of the PDO on seasonal to decadal time scales. I find that 1) CHFP2 is successful at predicting the PDO at the seasonal time scale measured by mean-square skill score and correlation skill. Weather "noise" unpredictable at the seasonal time scale generated by substantial North Pacific storm track activity that coincides with a shallow oceanic

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. 77 FR 53179 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-31

    ... National Oceanic and Atmospheric Administration RIN 0648-XC195 North Pacific Fishery Management Council... Management Council's (NPFMC) Crab Plan Team (CPT) will meet in Seattle, WA. DATES: The meeting will be held... Management Council, 605 W. 4th Avenue, Suite 306, Anchorage, AK 99501-2252. FOR FURTHER INFORMATION...

  17. 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...

  18. 75 FR 35443 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-22

    ... National Oceanic and Atmospheric Administration RIN 0648-XX01 North Pacific Fishery Management Council... Management Council's Scientific and Statistical Committee (SSC), and Groundfish Plan Team members will hold a workshop via Web-Ex, July 8, 2010, beginning at 12:30 p.m. Alaska Standard Time (AST) to review methods...

  19. 75 FR 23244 - North Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-03

    ...; Public Meeting AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION: Notice of a public meeting. SUMMARY: North Pacific Fishery Management... 305(c) of the Magnuson-Stevens Act, provided the public has been notified of the Council's intent...

  20. 77 FR 51521 - North Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-24

    ... 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 Fishery... interpretation or other auxiliary aids should be directed to Gail Bendixen, (907) 271-2809, at least 5...

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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

  6. 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

  7. 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.

  8. Glider observations of the North Equatorial Current in the western tropical Pacific

    NASA Astrophysics Data System (ADS)

    Schönau, Martha C.; Rudnick, Daniel L.

    2015-05-01

    The North Equatorial Current (NEC) of the Pacific Ocean advects subtropical, subpolar, and tropical water masses. Repeat underwater glider observations of the NEC from June 2009 to January 2014 along 134.3°E provide absolute zonal geostrophic velocity, transport, and water mass structure at length scales of 10-1000 km. The NEC is strongest near the surface and persistent eastward undercurrents are identified deeper than potential density surface 26 kg m-3 at 9.6°N and 13.1°N. Mean transport from the surface to 27.3 kg m-3 and 8.5°N-16.5°N is 37.6 Sv (106 m3 s-1), with a standard deviation of 15.6 Sv. The transport variability is greatest deeper than 26 kg m-3 due to undercurrent variability. Wavelet analysis at scales of 10-80 km reveals extrema of fine-scale salinity variance along isopycnals (spice variance). High spice variance is found in the North Pacific Tropical Water (NPTW) and the North Pacific Intermediate Water (NPIW), with a spice variance minimum between water masses at 25.5 kg m-3. A horizontal Cox number, CH, relates salinity variance at fine scales (10-80 km) to that at greater length scales (120-200 km). As a function of density, CH is nearly vertically uniform, indicating that the stirring of mean salinity gradients enhances fine-scale salinity variance. NPTW, with an estimated horizontal eddy diffusivity of order 104 m s-2, is a useful tracer for the region and may be used to relate the fine-scale salinity variance to an eddy diffusivity.

  9. 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

  10. 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.

  11. 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:...

  12. 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:...

  13. 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

  14. Climatic Variation in the Western Part of Subtropical North America during Late Last Glacial and Deglaciation: Some New Records and a Synthesis

    NASA Astrophysics Data System (ADS)

    Roy, P. D.; Quiroz-Jiménez, J. D.; Chávez Lara, C. M.; Sánchez Zavala, J. L.; Lozano-Santacruz, R.; Lopez-Balbiaux, N.

    2014-12-01

    Late Quaternary climate of western subtropical North America is related to the dynamics of summer as well as winter precipitation. During the last glacial maximum, it was hypothesized that the frequent winter storms provided more precipitation (COHMAP members, 1988) as the southern branch of the jet streams carried more moisture into the region (Kutzbach and Wright, 1985). However, the new global climate simulations do not provide indication of the jet stream split and some even suggest that the southern branch of the jet was weaker (Kim et al., 2008; Toracinta et al., 2004). In the last few years, the proxy records from the region have provided new information and suggested new hypothesis (Barron et al., 2012; Lyle et al., 2012; Roy et al., 2013). We present some new records of paleohydrological changes occurred over the late last glacial and deglaciation from the northwestern México. A compilation of all the important records from the region provides information about the geographic coverage of summer and winter precipitation. Minimal influence of summer as well as winter precipitation caused drier conditions over a large part of northern and northwestern Mexico (i.e. 29°-31°N) during the late last glacial (27-18 cal ka BP). Summer precipitation was restricted to the southern part of subtropical North America during >18 cal ka BP and it expanded to higher latitudes and covered different regions over the deglaciation (18-10 cal ka BP). We relate the different geographical coverage of summer precipitation to moisture flow sourced from the tropical and subtropical Pacific and Gulf of California during different intervals.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. Detecting the progression of ocean acidification from the saturation state of CaCO3 in the subtropical South Pacific

    NASA Astrophysics Data System (ADS)

    Murata, Akihiko; Hayashi, Kazuhiko; Kumamoto, Yuichiro; Sasaki, Ken-ichi

    2015-04-01

    Progression of ocean acidification in the subtropical South Pacific was investigated by using high-quality data from trans-Pacific zonal section at 17°S (World Ocean Circulation Experiment section P21) collected in 1994 and 2009. During this 15 year period, the CaCO3 saturation state of seawater with respect to calcite (Ωcal) and aragonite (Ωarg) in the upper water column (<400 dbar) decreased at rates of 0.037 a-1 and 0.025 a-1, respectively, east of 145°W longitude; these rates are among the fastest in the world's oceans. In contrast, at longitudes 170°E-145°W, Ωcal and Ωarg decreased relatively slowly, at 0.008 a-1 and 0.005 a-1, respectively. The Ωarg saturation horizon occurred at a depth of about 1200 dbar at the westernmost end of the section and shoaled eastward to about 20 dbar. From 1994 to 2009, it migrated upward at a rate of 5.2 dbar a-1 west of 145°W. Decomposition of the temporal changes of Ω (ΔΩ) showed that the accumulation of anthropogenic CO2 in the ocean accounted for more than half of ΔΩ. The more rapid rate of decline of Ω in the eastern section was attributable to a relatively large contribution of organic matter remineralization, whereas the slower rate in the central section was attributed to a decrease of anthropogenic CO2 uptake caused by rising water temperatures. An important finding of this study was that acidification of the upper water column was enhanced by processes related to the oxygen minimum zone in the eastern subtropical South Pacific Ocean.

  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. 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.

  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. 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

  6. 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

  7. 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

  8. 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

  9. Seasonal Variations in Alkenone Concentration and Production in the Oligotrophic North Pacific

    NASA Astrophysics Data System (ADS)

    Popp, B.; Prahl, F.; Sparrow, M.; Rust, T.

    2003-04-01

    Since its introduction in 1986, the alkenone unsaturation index (UK37) has been used extensively by the paleoceanographic community to determine variations in past sea-surface temperature (SST). Despite this widespread use, however, surprisingly little is yet known about where and when the UK37 signal exported to sediments is produced in the euphotic zone. Independent lines of empirical evidence suggest subsurface production within the euphotic zone to be an important source of alkenone export in subtropical regions of the Pacific and perhaps other oligotrophic parts of the world ocean. In the present study, we examined evidence for subsurface alkenone production in the oligotrophic subtropical North Pacific gyre at the Hawaii Ocean Time-series station ALOHA (22o 45N, 158oW) in three different seasons. Highest alkenone production rates, as determined by uptake of 13C-labeled inorganic carbon into alkenones during 24-hour in situ incubations, and highest alkenone standing stocks were found within (Spring, Fall) or just below (Summer) the surface mixed layer. Lowest alkenone standing stocks and lowest production rates were found within the deep chlorophyll maximum (DCM). Measured UK37 values were converted into growth temperature (gT) estimates using a culture-based calibration equation (UK37 = 0.034 T + 0.039; Prahl et al., 1988) and compared with water temperatures actually measured by CTD at the depth of sample collection. In most cases, alkenone gT under-estimated actual water temperature by 2-3oC when alkenone production rates were high and over-estimated actual water temperature by 3-4oC when production rates were low. These results suggest a non-thermal, physiological control on alkenone unsaturation and indicate that light-limited alkenone production at the DCM in the oligotrophic North Pacific is quantitatively unimportant. The physiological mechanisms responsible for these observations and the implication of these results for improved confidence in UK37

  10. 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

  11. 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.

  12. Interannual variability of the mixed layer winter convection and spiciness generation in the Eastern Subtropical North Atlantic

    NASA Astrophysics Data System (ADS)

    Kolodziejczyk, Nicolas; Reverdin, Gilles; Lazar, Alban

    2014-05-01

    The Argo data set is used to study the winter conditions in the north-eastern subtropical-tropical Atlantic during 2006-2012. During winter 2010, the mixed layer depth is abnormally shallow and a strong negative anomaly of density compensated salinity ('spiciness') is generated in the permanent pycnocline. This is primary explained by unusual weak buoyancy flux during the late winter in the subtropical north-eastern Atlantic (NEA). These conditions contrast with the 5 other studied winters, that show deeper mixed layer and positive spiciness anomalies in the permanent pycnocline. Particularly deep mixed layer and strong spiciness anomalies are observed during late winter 2012. The conditions during winter 2010 are likely explained by historically low North Atlantic Oscillation (NAO) and high Tropical North Atlantic index (TNA). Interannual variability of the eastern subtropical mixed layer is investigated using a simple 1-D bulk model including a mean thermohaline (temperature and salinity) linear profiles, and turbulent kinetic energy (TKE) conservation in the upper ocean layer, and interannual air-sea buoyancy forcing during the fall-winters 2006-2012. The mixed layer depth and the thermohaline ('spiciness') anomalies generated in a strongly compensated layer at the base of the mixed layer and in the permanent pycnocline are associated with the convective mixing driven by the atmospheric buoyancy flux during the boreal winter season.

  13. 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.

  14. 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

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

    NASA Astrophysics Data System (ADS)

    Li, Wenhong; Li, Laifang; Deng, Yi

    2015-07-01

    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.

  16. 75 FR 68756 - Eastern North Pacific Gray Whale; Notice of Petition Availability

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-09

    ... National Oceanic and Atmospheric Administration RIN 0648-XA018 Eastern North Pacific Gray Whale; Notice of... Pacific population of gray whales (Eschrichtius robustus) as a depleted stock under the Marine Mammal... assessment report for Eastern North Pacific gray whales is available on the Internet at the following...

  17. 77 FR 64490 - North Pacific Fishery Management Council (NPFMC); Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-22

    ... National Oceanic and Atmospheric Administration RIN 0648-XC307 North Pacific Fishery Management Council... Pacific Fishery Management Council's (Council) Steller Sea Lion Mitigation Committee (SSLMC) will meet in... Street, Juneau, AK. Council address: North Pacific Fishery Management Council, 605 W. 4th Ave., Suite...

  18. 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.

  19. 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.

  20. 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

  1. Nitrogen fixation rates at BATS and along the North Atlantic subtropical front

    NASA Astrophysics Data System (ADS)

    Charoenpong, C.; Larkum, J.; Lee, E. M.; Moisander, P.; Altabet, M. A.

    2012-12-01

    Nitrogen fixation is one of the major inputs of new N into the oligotrophic gyre of North Atlantic. In the Bermuda Atlantic Time-series Study (BATS), Trichodesmium spp. and diatom symbiont Richelia have been regarded as a major contributor to the newly fixed N. However, studies using nitrogenase gene (nifH) sequences have indicated a more diverse diazotroph assemblages including unicellular cyanobacteria in this oligotrophic system. Here, we report N2 fixation rates from diazotrophs of the size fraction that includes unicellular cyanobacteria and other bacteria. Samples were taken from BATS and several stations along the meridional transect from BATS southward to the area of the subtropical front (~27oN). Whole water samples were enriched with 15N-labelled N2, and incubated for 12-24 hours in simulated in situ conditions. Post-incubation filtration by using 20 micron size fractionation excluded Trichodesmium and potential diatom symbionts and constrained our rates to smaller non-filamentous N2-fixers. Sampling was conducted on two cruises during July and August 2012. 13C incorporation rates are also presented to show the photosynthetic activity. In addition, the 15N-enrichment of dissolved organic N (DON) was investigated in order to demonstrate the contribution of the diazotrophy to the regenerated nutrient and the potential link to the heterotrophic bacterial production.

  2. 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

  3. 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.

  4. Carbon disulfide in the North Atlantic and Pacific Oceans

    NASA Astrophysics Data System (ADS)

    Xie, Huixiang; Moore, Robert M.

    1999-03-01

    Carbon disulfide (CS2) was determined in surface waters of the North Atlantic and Pacific Oceans. The mean concentrations (and ranges) of CS2 in open ocean waters were 13.4 (7.8-26.1) pM S (picomol sulfur per liter) for the North Atlantic and 14.6 (7.2-27.5) pM S for the Pacific. The concentrations in the coastal waters of the North Atlantic averaged 26.4 pM S and ranged from 17.9 to 40.4 pM S. Warm waters generally contained higher levels of CS2 than did cold waters. All the study areas were found to be supersaturated in CS2 relative to the atmosphere based on calculations from published CS2 mixing ratios in the marine boundary layer and their Henry's law constants. Sea-to-air fluxes of CS2 were estimated using exchange velocities for spot and climatological wind speeds. The global oceanic flux extrapolated from this study is 0.18 Tg CS2 yr-1 and in the range 0.13-0.24 Tg CS2 yr-1. It is suggested that microbial processes, photochemical reactions, and phytoplankton activity are potential sources for oceanic CS2.

  5. 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.

  6. 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.


  7. 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.

  8. 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.

  9. 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...

  10. 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...

  11. 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...

  12. 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

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. Increasing coccolithophore abundance in the subtropical North Atlantic from 1990 to 2014

    NASA Astrophysics Data System (ADS)

    Krumhardt, K. M.; Lovenduski, N. S.; Freeman, N. M.; Bates, N. R.

    2015-11-01

    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 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) to show that coccolithophore populations in the North Atlantic Subtropical Gyre have been increasing significantly over the past two decades. Over 1991-2012, we observe a 37 % increase in euphotic zone-integrated coccolithophore abundance at BATS. We further demonstrate that variability in coccolithophore abundance here is positively correlated with variability in 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 1991 to 2012, we speculate that coccolithophore photosynthesis and perhaps calcification may have increased in response to anthropogenic CO2 input.

  18. Miocene biochronology and paleoceanography of the North Pacific

    USGS Publications Warehouse

    Keller, G.

    1981-01-01

    Biostratigraphic correlation based on microfossil datum levels, directly or indirectly tied to the paleomagnetic time scale, provides a high resolution time control for the Miocene in the equatorial and middle latitude North Pacific. Faunal changes and abundance fluctuations of planktic foraminiferal species combined with the oxygen Pacific. Faunal changes and abundance fluctuations of planktic foraminiferal species combined with the oxygen isotope record of foraminifers, reveal the paleoclimatic and paleoceanographic history. The planktic foraminiferal assemblage change in the early Miocene, extinction of Oligocene fauna and rise of a highly diverse Neogene fauna, appears to be related to increased water mass stratification in the world oceans presumably resulting from the establishment of circum-Antarctic circulation. An increase in the siliceous productivity in the eastern equatorial Pacific region between 20 and 18 Ma suggests that the vertical and horizontal circulation was intensified at that time. Climates cooled rapidly during the middle Miocene between 14 and 13 Ma suggesting the growth of a major east Antarctic ice sheet. Paleoclimatic conditions remained generally cool, although oscillating, during the late Miocene. In the late early to middle Miocene faunal provincialism developed between low and middle latitudes, and by late Miocene time a distinct provincialism similar to the present was established. ?? 1981.

  19. 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

  20. 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

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. A decade of acoustic thermometry in the North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Dushaw, B. D.; Worcester, P. F.; Munk, W. H.; Spindel, R. C.; Mercer, J. A.; Howe, B. M.; Metzger, K.; Birdsall, T. G.; Andrew, R. K.; Dzieciuch, M. A.; Cornuelle, B. D.; Menemenlis, D.

    2009-07-01

    Over the decade 1996-2006, acoustic sources located off central California (1996-1999) and north of Kauai (1997-1999, 2002-2006) transmitted to receivers distributed throughout the northeast and north central Pacific. The acoustic travel times are inherently spatially integrating, which suppresses mesoscale variability and provides a precise measure of ray-averaged temperature. Daily average travel times at 4-day intervals provide excellent temporal resolution of the large-scale thermal field. The interannual, seasonal, and shorter-period variability is large, with substantial changes sometimes occurring in only a few weeks. Linear trends estimated over the decade are small compared to the interannual variability and inconsistent from path to path, with some acoustic paths warming slightly and others cooling slightly. The measured travel times are compared with travel times derived from four independent estimates of the North Pacific: (1) climatology, as represented by the World Ocean Atlas 2005 (WOA05); (2) objective analysis of the upper-ocean temperature field derived from satellite altimetry and in situ profiles; (3) an analysis provided by the Estimating the Circulation and Climate of the Ocean project, as implemented at the Jet Propulsion Laboratory (JPL-ECCO); and (4) simulation results from a high-resolution configuration of the Parallel Ocean Program (POP) model. The acoustic data show that WOA05 is a better estimate of the time mean hydrography than either the JPL-ECCO or the POP estimates, both of which proved incapable of reproducing the observed acoustic arrival patterns. The comparisons of time series provide a stringent test of the large-scale temperature variability in the models. The differences are sometimes substantial, indicating that acoustic thermometry data can provide significant additional constraints for numerical ocean models.

  8. [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

  9. 77 FR 59900 - North Pacific Fishery Management Council (NPFMC); Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-01

    ... National Oceanic and Atmospheric Administration RIN 0648-XC258 North Pacific Fishery Management Council... Fishery Management Council's (Council) Steller Sea Lion Mitigation Committee (SSLMC) will meet in Juneau... Street, Juneau, AK. Council address: North Pacific Fishery Management Council, 605 W. 4th Ave., Suite...

  10. Mid-late Holocene North Pacific trade winds as inferred from deep-sea coral skeletal δ15N and δ13C biogeochemistry

    NASA Astrophysics Data System (ADS)

    Guilderson, T. P.; Mccarthy, M. D.; Dunbar, R. B.; Englebrecht, A.; Roark, E.

    2013-12-01

    δ15N and δ13C data obtained from samples of proteinaceous deep-sea corals collected from the North Pacific Subtropical Gyre (Hawai'ian archipelago) and the central equatorial Pacific (Line Islands) document multi-decadal to century scale variability in the isotopic composition of surface-produced particulate organic matter exported to the deep sea. Comparison of the δ13C data, where Line Island samples are 0.6‰ more positive than the Hawai'ian samples, support the contention that the North Pacific Subtropical Gyre is more efficient than the tropical upwelling system at trapping and/or recycling nutrients within the mixed layer. δ15N values from the Line Island samples are also more positive than those from the central gyre, and within the Hawai'ian samples there is a gradient with more positive δ15N values in samples from the main Hawai'ian Islands versus French Frigate Shoals in the Northwestern Hawai'ian Islands. The gradient in the Hawai'ian samples likely reflects the relative importance of algal acquisition of metabolic N via dissolved seawater nitrate uptake versus nitrogen fixation. The Hawai'ian sample set also exhibits a strong decrease in δ15N values from the mid-Holocene to present. We hypothesize that this decrease is most likely the result of decreasing tradewinds, and possibly a commensurate decrease in entrainment of more positive δ15N-NO3 subthermocline water masses.

  11. 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

  12. 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.

  13. Quasi-stationary North Equatorial Undercurrent jets across the tropical North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Qiu, Bo; Rudnick, Daniel L.; Chen, Shuiming; Kashino, Yuji

    2013-05-01

    Subthermocline circulation in the tropical North Pacific Ocean (2°N-30°N) is investigated using profiling float temperature-salinity data from the International Argo and the Origins of the Kuroshio and Mindanao Current (OKMC) projects. Three well-defined eastward jets are detected beneath the wind-driven, westward flowing North Equatorial Current. Dubbed the North Equatorial Undercurrent (NEUC) jets, these subthermocline jets have a typical core velocity of 2-5 cms-1 and are spatially coherent from the western boundary to about 120°W across the North Pacific basin. Centered around 9°N, 13°N, and 18°N in the western basin, the NEUC jet cores tend to migrate northward by ˜4° in the eastern basin. Vertically, the cores of the southern, central, and northern NEUC jets reside on the 26.9, 27.2, and 27.3 σθsurfaces, respectively, and they tend to shoal to lighter density surfaces, by about 0.2 σθ, as the jets progress eastward.

  14. 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. PMID:23231094

  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

    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 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

  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. Simulated rapid warming of abyssal North Pacific waters.

    PubMed

    Masuda, Shuhei; Awaji, Toshiyuki; Sugiura, Nozomi; Matthews, John Philip; Toyoda, Takahiro; Kawai, Yoshimi; Doi, Toshimasa; Kouketsu, Shinya; Igarashi, Hiromichi; Katsumata, Katsuro; Uchida, Hiroshi; Kawano, Takeshi; Fukasawa, Masao

    2010-07-16

    Recent observational surveys have shown significant oceanic bottom-water warming. However, the mechanisms causing such warming remain poorly understood, and their time scales are uncertain. Here, we report computer simulations that reveal a fast teleconnection between changes in the surface air-sea heat flux off the Adélie Coast of Antarctica and the bottom-water warming in the North Pacific. In contrast to conventional estimates of a multicentennial time scale, this link is established over only four decades through the action of internal waves. Changes in the heat content of the deep ocean are thus far more sensitive to the air-sea thermal interchanges than previously considered. Our findings require a reassessment of the role of the Southern Ocean in determining the impact of atmospheric warming on deep oceanic waters. PMID:20576848

  20. 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

  1. 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.

  2. 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.

  3. The Mexican Coastal Current: A subsurface seasonal bridge that connects the tropical and subtropical Northeastern Pacific

    NASA Astrophysics Data System (ADS)

    Gómez-Valdivia, F.; Parés-Sierra, A.; Flores-Morales, A. L.

    2015-11-01

    We used a three-dimensional numerical model to analyze the seasonal variability of the coastal circulation off SW Mexico. In agreement with previous research, our model reproduced a Mexican Coastal Current (MCC) that dominates the regional poleward circulation. The modeled dynamics evidenced an energetic semiannual component that governed the subsurface seasonal variability of this poleward flow. Below the thermocline the MCC was stronger during spring and fall, when it reached subsurface seasonal-averaged velocities of ∼10 cms-1 and flowed continuously from the Gulf of Tehuantepec to the entrance of the Gulf of California. There, the subsurface MCC bifurcated in one branch that continued along the coast of mainland Mexico and a second branch that crossed the gulf and joined the California Undercurrent. Instead of the local wind, the semiannual MCC variability was induced by the transit of equatorial Kelvin waves whose upwelling (downwelling) phase propagation strengthen (weakened) the subsurface poleward circulation along the Tropical Pacific off Mexico. The MCC dynamics reported in this study accounts for the, previously reported, semiannual variability of the alongshore transport and salinity content in the southern Gulf of California. Moreover, the subsurface bridge between the MCC and the California Current System represents an external source of momentum that helps to explain the intensification of the California Undercurrent during spring and fall.

  4. Deepwater formation in the North Pacific during the Last Glacial Termination.

    PubMed

    Okazaki, Y; Timmermann, A; Menviel, L; Harada, N; Abe-Ouchi, A; Chikamoto, M O; Mouchet, A; Asahi, H

    2010-07-01

    Between approximately 17,500 and 15,000 years ago, the Atlantic meridional overturning circulation weakened substantially in response to meltwater discharges from disintegrating Northern Hemispheric glacial ice sheets. The global effects of this reorganization of poleward heat flow in the North Atlantic extended to Antarctica and the North Pacific. Here we present evidence from North Pacific paleo surface proxy data, a compilation of marine radiocarbon age ventilation records, and global climate model simulations to suggest that during the early stages of the Last Glacial Termination, deep water extending to a depth of approximately 2500 to 3000 meters was formed in the North Pacific. A switch of deepwater formation between the North Atlantic and the North Pacific played a key role in regulating poleward oceanic heat transport during the Last Glacial Termination. PMID:20616275

  5. 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.

  6. 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.

  7. 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. PMID:25333462

  8. 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

  9. 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.

  10. Marine boundary layer over the subtropical southeast Pacific during VOCALS-REx - Part 1: Mean structure and diurnal cycle

    NASA Astrophysics Data System (ADS)

    Rahn, D. A.; Garreaud, R. D.

    2009-12-01

    Atmospheric subsidence over the subtropical southeast Pacific (SEP) leads to a low-level anticyclonic circulation, a cool sea surface and a cloud-topped marine boundary layer (MBL). Observations in this region from a major field campaign during October and November 2008, the VOCALS Regional Experiment, provide ample data to characterize the lower atmospheric features over the SEP. The observations are also useful to test the ability of an area-limited, high-resolution atmospheric model to simulate the SEP conditions. Observations and model-results (where appropriate) improve the characterization of the mean state (Part 1) and variability (Part 2) of the lower troposphere including circulation, MBL characteristics and the upsidence wave. Along 20° S the MBL is generally deeper offshore (1600 m at 85° W) but there is also considerable variability. MBL depth and variability decrease towards the coast and maximum inversion strength is detected between 74-76° W. Southeasterly trades prevail within the MBL although the wind speed decreases toward the coast. Above the MBL along the coast of Chile, flow is northerly, has a maximum at 3 km, and extends westward to ~74° W, apparently due to the mechanical blocking exerted by the Andes upon the westerly flow aloft. Mean MBL features along northern Chile (18-25° S) are remarkably similar (e.g., MBL depth just below 1 km) in spite of different SST. Observed diurnal cycles of the temperature at the coast and further offshore exhibit a number of conspicuous features that are consistent with the southwestward propagation of an upsidence wave initiated during late evening along the south Peru coast. Furthermore, the passage of the vertical motion results in either constructive or deconstructive interference with the radiatively-forced diurnal cycle of MBL depth.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Living benthic foraminifera of the Hess Rise and Suiko Seamount, central North Pacific

    NASA Astrophysics Data System (ADS)

    Ohkushi, Ken'ichi; Natori, Hiro'o.

    2001-05-01

    Rose-Bengal-stained benthic foraminifera in six pilot-core samples and one multicore sample collected from the Hess Rise and Suiko Seamount in August 1994 were studied in order to understand foraminiferal distributions between two areas divided by an oceanic front in the central North Pacific. Samples from the Hess Rise were collected in depths of 2167-3354 m under the warm, saline Kuroshio Extension, while samples from Suiko Seamount came from depths of 1811-1955 m under the cold, less-saline subarctic current. Sediment-trap results for the year prior to our sediment sampling show that organic matter fluxes were about 2.5 times greater at Suiko Seamount than at the Hess Rise. However, the hydrographic structure between 1800 and 3400 m, based on CTD observations, is almost the same at both sites. Temperature decreases from 2.2 to 1.7°C over the depth range of 1800-3400 m, salinity increases from 34.5 to 34.7, and the dissolved oxygen content gradually increases from 1.5 to 3.0 ml l -1. The faunal populations at the Hess Rise are quite different from those at Suiko Seamount. The abundant species at the Hess Rise are Epistominella exigua, Brizalina pacifica, Fursenkoina cedrosensis and Alabaminella weddellensis. These species characteristically inhabit phytodetrital aggregates deposited on an oligotrophic seafloor. The populations at Suiko Seamount are dominated by Triloculina frigida, Lagenammina cf. arenulata, Reophax subfusiformis, and Reophax scorpiurus. The reason for differences between these populations is unclear. However, the typical phytodetritus-dwelling species E. exigua is dominant at the Hess Rise, which is located in a subtropical area that has a pulsed supply of settling organic matter in the spring. On the other hand, E. exigua is rare at Suiko Seamount, a subarctic site where there are more stable and greater fluxes of organic matter in summer and autumn. Occurrences of this species may be related to the seasonally short supply of organic matter

  16. 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.

  17. Frequency of marine heatwaves in the North Atlantic and North Pacific since 1950

    NASA Astrophysics Data System (ADS)

    Scannell, Hillary A.; Pershing, Andrew J.; Alexander, Michael A.; Thomas, Andrew C.; Mills, Katherine E.

    2016-03-01

    Extreme and large-scale warming events in the ocean have been dubbed marine heatwaves, and these have been documented in both the Northern and Southern Hemispheres. This paper examines the intensity, duration, and frequency of positive sea surface temperature anomalies in the North Atlantic and North Pacific Oceans over the period 1950-2014 using an objective definition for marine heatwaves based on their probability of occurrence. Small-area anomalies occur more frequently than large-area anomalies, and this relationship can be characterized by a power law distribution. The relative frequency of large- versus small-area anomalies, represented by the power law slope parameter, is modulated by basin-scale modes of natural climate variability and anthropogenic warming. Findings suggest that the probability of marine heatwaves is a trade-off between size, intensity, and duration and that region specific variability modulates the frequency of these events.

  18. 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

  19. Dissolved iron anomaly in the deep tropical-subtropical Pacific: Evidence for long-range transport of hydrothermal iron

    NASA Astrophysics Data System (ADS)

    Wu, Jingfeng; Wells, Mark L.; Rember, Robert

    2011-01-01

    Dissolved iron profiles along a north-south transect along 158°W in the tropical Pacific show evidence of two deepwater anomalies. The first extends from Station ALOHA (22.78°N) to the equator at ˜1000-1500 m and lies below the maximum apparent oxygen utilization and nutrient (N, P) concentrations. The feature is not supported by vertical export processes, but instead corresponds with the lateral dilution field of δ 3He derived from the Loihi seamount, Hawaii, though a sediment source associated with the Hawaiian Island Chain cannot be entirely ruled out. The second, deeper (2000-3000 m) anomaly occurs in tropical South Pacific waters (7°S) and also does not correlate with the depths of maximum nutrient concentrations or apparent oxygen utilization, but it does coincide closely with δ 3He emanating from the East Pacific Rise, more than 5000 km to the east. We hypothesize that these anomalies represent the long-range (>2000 km) transport of hydrothermal iron residuals, stabilized against scavenging by complexation with excess organic ligands in the plume source regions. Such trace leakage of hydrothermal iron to distal plume regions would have been difficult to identify in most hydrothermal vent mapping studies because low analytical detection limits were not needed for the proximal plume regions. These findings suggest that hydrothermal activity may represent a major source of dissolved iron throughout the South Pacific deep basin today, as well as other regions having high mid-ocean spreading rates in the geologic past. In particular, we hypothesize that high spreading rates along the South Atlantic and Southern Ocean mid-oceanic ridges, combined with the upwelling ventilation of these distal hydrothermal plumes, may have increased ocean productivity and carbon export in the Southern Ocean. Assessing the magnitude and persistence of dissolved hydrothermal iron in basin scale deep waters will be important for understanding the marine biogeochemistry of iron

  20. Interdecadal changes in the storm track activity over the North Pacific and North Atlantic

    NASA Astrophysics Data System (ADS)

    Lee, Sun-Seon; Lee, June-Yi; Wang, Bin; Ha, Kyung-Ja; Heo, Ki-Young; Jin, Fei-Fei; Straus, David M.; Shukla, Jagadish

    2012-07-01

    Analysis of NCEP-NCAR I reanalysis data of 1948-2009 and ECMWF ERA-40 reanalysis data of 1958-2001 reveals several significant interdecadal changes in the storm track activity and mean flow-transient eddy interaction in the extratropics of Northern Hemisphere. First, the most remarkable transition in the North Pacific storm track (PST) and the North Atlantic storm track (AST) activities during the boreal cold season (from November to March) occurred around early-to-mid 1970s with the characteristics of global intensification that has been noticed in previous studies. Second, the PST activity in midwinter underwent decadal change from a weak regime in the early 1980s to a strong regime in the late 1980s. Third, during recent decade, the PST intensity has been enhanced in early spring whereas the AST intensity has been weakened in midwinter. Finally, interdecadal change has been also noted in the relationship between the PST and AST activities and between the storm track activity and climate indices. The variability of storm track activity is well correlated with the Pacific Decadal Oscillation and North Atlantic Oscillation prior to the early 1980s, but this relationship has disappeared afterward and a significant linkage between the PST and AST activity has also been decoupled. For a better understanding of the mid-1970s' shift in storm track activity and mean flow-transient eddy interaction, further investigation is made by analyzing local barotropic and baroclinic energetics. The intensification of global storm track activity after the mid-1970s is mainly associated with the enhancement of mean meridional temperature gradient resulting in favorable condition for baroclinic eddy growth. Consistent with the change in storm track activity, the baroclinic energy conversion is significantly increased in the North Pacific and North Atlantic. The intensification of the PST and AST activity, in turn, helps to reinforce the changes in the middle-to-upper tropospheric

  1. 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

  2. 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.

  3. The Variation of Tropical Cyclone Rainfall within the North Atlantic and Pacific as Observed from Satellites

    NASA Technical Reports Server (NTRS)

    Rodgers, Edward; Pierce, Harold; Adler, Robert

    1999-01-01

    Tropical cyclone monthly rainfall amounts are estimated from passive microwave satellite observations in the North Atlantic and in three equal geographical regions of the North Pacific (i.e., Western, Central, and Eastern North Pacific). 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 1987-1989, 1991-1998 North Atlantic and Pacific rainfall during June-November when tropical cyclones are most abundant. To estimate these tropical cyclone rainfall amounts, mean monthly rain rates are derived from the Defence Meteorological Satellite Program (DMSP) Special Sensor Microwave/ Radiometer (SSM/I) observations within 444 km radius of the center of those North Atlantic and Pacific tropical cyclones that reached storm stage and greater. These rain rate observations are then multiplied by the number of hours in a given month. Mean monthly rainfall amounts are also constructed for all the other North Atlantic and Pacific raining systems during this eleven year period for the purpose of estimating the geographical distribution and intensity of rainfall contributed by non-tropical cyclone systems. Further, the combination of the non-tropical cyclone and tropical cyclone (i.e., total) rainfall is constructed to delineate the fractional amount that tropical cyclones contributed to the total North Pacific rainfall.

  4. 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.

  5. Movements of pacific bluefin tuna ( Thunnus orientalis) in the Eastern North Pacific revealed with archival tags

    NASA Astrophysics Data System (ADS)

    Boustany, Andre M.; Matteson, Robyn; Castleton, Michael; Farwell, Charles; Block, Barbara A.

    2010-07-01

    In this study, 253 Pacific bluefin tuna were archivally tagged off the coast of California, USA and Baja California, Mexico between August 2002 and August 2005. One hundred and fifty-seven fish were recaptured and 143 datasets were obtained and analyzed, yielding electronic tag datasets of up to 1203 days. Mean days at large for the 143 fish was 359 ± 248 (SD) days. A total of 38,012 geolocations were calculated from light-based longitude and SST-based latitude estimates, allowing us to examine the seasonal movement of juvenile bluefin tuna off the west coast of North America. Electronic tagged bluefin tuna showed repeatable seasonal movements along the west coast of North America. Bluefin tuna were found farthest south in the spring when they were located off southern Baja California, Mexico and farthest north in the fall when fish were found predominately off central and northern California. Fish showed latitudinal movement patterns that were correlated with peaks in coastal upwelling-induced primary productivity. Interannual variation in the locality of these productivity peaks was linked with a corresponding movement in the distribution of tagged fish. Overall geographical area occupied by tagged bluefin varied with primary productivity, with fish being more tightly clustered in areas of high productivity and more dispersed in regions of low productivity. In the spring through fall, bluefin tuna were located in areas with the highest levels of primary productivity available in the California Current ecosystem. However, in the winter months, tagged bluefin tuna were found in areas with lower productivity compared to other regions along the coast at that time of year suggesting that during the winter, bluefin tuna are feeding on aggregations of pelagic red crabs, sardines and anchovies that preferentially spawn in areas of reduced coastal upwelling.

  6. 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

  7. Marine boundary layer over the subtropical southeast Pacific during VOCALS-REx - Part 1: Mean structure and diurnal cycle

    NASA Astrophysics Data System (ADS)

    Rahn, D. A.; Garreaud, R.

    2010-05-01

    Atmospheric subsidence over the subtropical southeast Pacific (SEP) leads to a low-level anticyclonic circulation, a cool sea surface and a cloud-topped marine boundary layer (MBL). Observations in this region from a major field campaign during October and November 2008, the VOCALS Regional Experiment, provide ample data to characterize the lower atmospheric features over the SEP. The observations are also useful to test the ability of an area-limited, high-resolution atmospheric model to simulate the SEP conditions. Observations and model-results (where appropriate) improve the characterization of the mean state (Part 1) and variability (Part 2) of the lower troposphere including circulation, MBL characteristics and the upsidence wave. Along 20° S the MBL is generally deeper offshore (1600 m at 85° W) but there is also considerable variability. MBL depth and variability decrease towards the coast and maximum inversion strength is detected between 74-76° W. Weather Research and Forecasting (WRF) simulations underestimate MBL height the most near the coast but improve offshore. Southeasterly trades prevail within the MBL although the wind speed decreases toward the coast. Above the MBL along the coast of Chile, flow is northerly, has a maximum at 3 km, and extends westward to ~74° W, apparently due to the mechanical blocking exerted by the Andes upon the westerly flow aloft. Mean MBL features along northern Chile (18-25° S) are remarkably similar (e.g., MBL depth just below 1 km) in spite of different SST. Observed diurnal cycles of the temperature at the coast and further offshore exhibit a number of conspicuous features that are consistent with the southwestward propagation of an upsidence wave initiated during late evening along the south Peru coast. Furthermore, the passage of the vertical motion results in either constructive or deconstructive interference with the radiatively-forced diurnal cycle of MBL depth. Interference is clearly seen in the soundings

  8. 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.

  9. Vertical velocity estimates in the North Pacific using Argo floats

    NASA Astrophysics Data System (ADS)

    Freeland, Howard J.

    2013-01-01

    Vertical velocity in the oceans is critical for maintenance of the structure of the main thermoclines and the transport of nutrients from deepwater towards the surface and thus is an important variable for understanding the dynamics of the ocean and the transport of scalar variables. In the mid 1970s the author was engaged in discussions with Tom Rossby about how SOFAR floats might be used to observe the vertical component of velocity. This paper in some sense follows on from those discussions almost 40 years later. In this paper the Argo array is used to compute the horizontal volume divergence in a control volume in the North Pacific. Divergence is found and this must be related to a volume flux through the base of the control volume. The implied vertical velocity is large and various tests are proposed to determine whether or not the estimate is plausible. The first test shows that a vertical velocity this large is necessary to close the salt budget. The second test shows that the vertical velocity balances about half of the observed heat divergence, the remainder is then accounted for by heat flux at the sea surface. Finally the time variable vertical velocity is computed and used to compute the evolution of the salt content in the control volume. Thus though the estimated vertical velocity is surprisingly large, it passes plausibility tests.

  10. 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

  11. 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. PMID:18309359

  12. 76 FR 66274 - North Pacific Fishery Management Council (NPFMC); Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-26

    ... Fishery Management Council's (Council) Gulf of Alaska (GOA) and Bering Sea/Aleutian Islands (BS/AI... (GOA Plan Team) and Traynor Room (BS/AI Plan Team), Seattle, WA. Council address: North Pacific...

  13. 77 FR 31329 - North Pacific Fishery Management Council (NPFMC); Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-25

    ... Steller Sea Lion Protection Measures EIS (77 FR 22750, April 17, 2012). Information on EIS development... National Oceanic and Atmospheric Administration RIN 0648-XC047 North Pacific Fishery Management Council... Pacific Fishery Management Council's (Council) Steller Sea Lion Mitigation Committee (SSLMC) will meet...

  14. Decadal oscillation of autumn precipitation in Central Vietnam modulated by the East Pacific-North Pacific (EP-NP) teleconnection

    NASA Astrophysics Data System (ADS)

    Li, R.; Wang, S.-Y.; Gillies, R. R.; Buckley, B. M.; Truong, L. H.; Cho, C.

    2015-02-01

    Autumn precipitation over Central Vietnam is associated with an increase in the occurrence of tropical cyclones that lead to frequent flooding and pose a significant threat to lives and property. The present analyses reveal a pronounced decadal oscillation of autumn precipitation in Central Vietnam within the 8-11 year frequency band that is modulated by the East Pacific-North Pacific (EP-NP) teleconnection. The negative phase of the EP-NP pattern is associated with a positive sea surface temperature (SST) anomaly in the South China Sea (SCS) that induces low-level convergence, enhances convection, and increases precipitation over Central Vietnam and adjacent islands including Hainan (China) and the Philippines. This circulation feature around the SCS is embedded in a large-scale circulation associated with SST anomalies across the Pacific Ocean—i.e., cooling in the Eastern and Central tropical Pacific sandwiched by warming in the North and South Pacific as well as the Western Pacific Ocean. The positive phase of the EP-NP features opposite SST and circulation anomalies, with the result being reduced rainfall in Central Vietnam. This out-of-phase relationship and shared decadal spectral coherence between the EP-NP index and autumn precipitation in Central Vietnam might be useful for future climate predictions and flood management.

  15. 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

  16. 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

  17. Estimating Historical Eastern North Pacific Blue Whale Catches Using Spatial Calling Patterns

    PubMed Central

    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

  18. 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

  19. 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. PMID:26642318

  20. 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

  1. 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.

  2. 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.

  3. 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

  4. 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

  5. Variations in intermediate and deep ocean circulation in the subtropical northwestern Pacific from 26 ka to present based on a new calibration for Mg/Ca in benthic foraminifera

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    To understand variations in intermediate and deep ocean circulation in the North Pacific, bottom water temperatures (BWT), carbon isotopes (δ13C) of benthic foraminifera, and oxygen isotopes (δ18O) of seawater at a water depth of 1166 m were reconstructed from 26 ka to present. A new regional Mg/Ca calibration for the benthic foraminifera Cibicidoides wuellerstorfi was established to convert the benthic Mg/Ca value to BWT, based on twenty-six surface sediment samples and a core top sample retrieved around Okinawa Island. In addition, core GH08-2004, retrieved from 1166 m water depth east of Okinawa Island, was used to reconstruct water properties from 26 ka to present. During the Last Glacial Maximum (LGM), from 24 to 18 ka, BWT appeared to be relatively constant at approximately 2 °C, which is ~1.5-2 °C lower than today. One of the prominent features of our BWT records was a millennial-scale variation in BWT during the last deglaciation, with BWT higher during Heinrich event 1 (H1; ~17 ka) and the Younger Dryas (YD; ~12 ka) and lower during the Bølling/Allerød (B/A; ~14 ka). The record of seawater δ18O in core GH08-2004 exhibited a rapid increase in association with the rapid warming of BWT at 17 ka, likely due to the reduced precipitation in the North Pacific in response to less moisture transport from the equatorial Atlantic as a result of the collapse of the Atlantic Meridional Overturning Circulation. During the interval from 17 to 15 ka, the bottom water temperature tended to decrease in association with a decrease in the carbon isotope values of C. wuellerstorfi, likely as a result of increased upwelling of the older water mass that was stored in the abyssal Pacific during the glacial time. The timing of the increased upwelling coincided with the deglacial atmospheric CO2 rise initiated at ~17 ka, and suggested that the increased upwelling in the subtropical northwestern Pacific from 17 to 15 ka contributed to the carbon release from the Pacific into

  6. 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.

  7. 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

  8. 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

  9. Vertical distribution of scandium in the north central Pacific

    NASA Astrophysics Data System (ADS)

    Amakawa, Hiroshi; Nomura, Miho; Sasaki, Kazunori; Oura, Yasuji; Ebihara, Mitsuru

    2007-06-01

    The concentrations of scandium (Sc) in seawater, which have remained unreported since the early 1970s, were determined together with those of yttrium (Y) and lanthanides (Ln) with samples from the north central Pacific Ocean (St. BO-3). The Sc concentration shows a so-called nutrient-like profile: it increases gradually from the surface (about 2 pmol/kg) to the ocean floor (about 20 pmol/kg). That pattern closely resembles those of Y and Ln (correlation coefficient (r) > 0.92). Some light-to-middle Ln (Pr-Tb) exhibit a closer correlation with Sc than do Y, La, or heavy Ln (Ho-Lu). In contrast, Y/Sc and Ln/Sc ratios (elemental abundance ratios) indicate that Sc is depleted compared to either Y or Ln in seawater more than in loess, which represents chemical compositions of crustal material. These observations offer a conflicting view of chemical reactivity related Y, Ln, and Sc: r values show that the chemical reactivity of Sc resembles those of Y and Ln, but differences of Y/Sc and Ln/Sc ratios in seawater and in loess suggest that the chemical reactivity of Sc differs from those of Y and Ln. More Sc data for seawater are necessary to clarify the chemical reactivity of Sc in the ocean. We also propose that comparative studies of vertical profiles of Sc and such elements as Fe, Ti, Zr, and Hf showing so-called nutrient-like profiles at the same oceanic stations would be helpful and effective for clarifying the behavior of Sc in the ocean.

  10. 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

  11. 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

  12. 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.

  13. 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).

  14. 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

  15. Bulk and Compound-Specific Stable Nitrogen Isotopes in Plankton Reveal Large Impact of Diazotrophy across the Subtropical North Atlantic

    NASA Astrophysics Data System (ADS)

    Mompean de la Rosa, M.; McCarthy, M.; Bode, A.

    2012-12-01

    Enhanced stratification linked to global warming is predicted to decrease nutrient input from deep waters, and may therefore increase oligotrophy in the subtropical ocean. However, nitrogen fixation in many subtropical regions also supports a significant fraction of primary production, a process likely to be enhanced by the same warm/stratified conditions. The shifting balance between major nutrient sources with global change may alter subtropical food webs, possibly strongly affecting the production and export of organic matter. In this study we examined the spatial variability of stable nitrogen isotopes in plankton size fractions in the upper 200 m in a high spatial resolution transect across the Atlantic (24N) during the Malaspina-2010. Our main goal was to determine the major origin of nitrogen for plankton production. Bulk stable isotopes in all size fractions showed a nearly symmetrical spatial distribution, with the lowest values (σ15N <1‰) in the central zone, and were inversely correlated to the abundance of the nitrogen-fixer Trichodesmium. Diazotrophy was estimated to account for >50% of organic nitrogen in the central zone, however it was also very significant (>30%) in eastern and western zones. The relative nitrogen contribution from diazotrophy also increased with increasing plankton size fraction, suggesting the increasing concentration (importance) of recently fixed nitrogen at higher trophic levels, with potential implication for sources of exported organic N. To further explore a possible linkage with trophic position, we also measured compound-specific σ15N values of amino acids, which allowed us to explicitly calculate average trophic position for different plankton size classes. The σ15N value of Phe was then used as direct molecular-level proxy for σ15N value of primary production across the plankton size spectrum. These results indicate that the zone influenced by diazotrophy in the North Atlantic is much larger than reported in

  16. 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.

  17. 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.

  18. Seasonal forecasting of intense tropical cyclones over the North Atlantic and the western North Pacific basins

    NASA Astrophysics Data System (ADS)

    Choi, Woosuk; Ho, Chang-Hoi; Jin, Chun-Sil; Kim, Jinwon; Feng, Song; Park, Doo-Sun R.; Schemm, Jae-Kyung E.

    2016-02-01

    Intense tropical cyclones (TCs) accompanying torrential rain and powerful wind gusts often cause substantial socio-economic losses in the regions around their landfall. This study analyzes intense TCs in the North Atlantic (NA) and the western North Pacific (WNP) basins during the period 1982-2013. Different intensity criteria are used to define intense TCs for these two basins, category 1 and above for NA and category 3 and above for WNP, because the number of TCs in the NA basin is much smaller than that in the WNP basin. Using a fuzzy clustering method, intense TC tracks in the NA and the WNP basins are classified into two and three representative patterns, respectively. On the basis of the clustering results, a track-pattern-based model is then developed for forecasting the seasonal activities of intense TCs in the two basins. Cross-validation of the model skill for 1982-2013 as well as verification of a forecast for the 2014 TC season suggest that our intense TC model is applicable to operational uses.

  19. Origin of millennial-scale climate signals in the subtropical North Atlantic

    NASA Astrophysics Data System (ADS)

    Billups, K.

    2011-12-01

    In this study, I am testing the hypothesis that millennial-scale climate signals in the northwestern subtropical Atlantic are linked to external driving factors such as the harmonics of precession. The test is based on the observation that the precession period is not stationary through time. For example, between 900 and 340 Ka the time interval between successive precession minima (or maxima) ranges primarily from 17 kyr to 21 kyr with discrete intervals lasting up to ~30 kyr (spectral power centered on the 23 kyr and 19 kyr periodicities). After 340 Ka, however, precession minima (or maxima) consistently occur at longer intervals, between 21 kyr and 25 kyr (spectral power focused at the 23 kyr period). If in proxy records millennial-scale variations reflect the harmonics of precession, I expect that the millennial-scale periodicity associated with the 19 kyr precession period (e.g., the 4.8 kyr peak) loses power as the primary orbital peak loses power at 340 Ka. First order tests of this idea can be made using published planktic foraminiferal δ18O records from ODP Site 1059 (Hagen and Keigwin, 2002; Oppo et al., 2001) in the northwestern subtropical Atlantic spanning Marine Isotope Stages 2-6 (~20-150 Ka) and Site 1058 spanning MIS 12-22 (~450-900 Ka, Weirauch et al., 2008). After filtering the records to remove the 100 kyr cycle, the older time slice contains both precession peaks (23 and 19 kyr). Significant (95% confidence interval) suborbital peaks occur at 12 kyr, 5.7 kyr and 5.0 kyr, which are close to the periodicities of the expected harmonics. The younger time slice shows only one precession peak centered at ~23 kyr and significant (95% confidence interval) sub-orbital peaks at 11.2 kyr, and 5 kyr. Only the 11.2 kyr peak agrees with the expected period of the second harmonic of the 23 kyr precession peak. We are currently generating high resolution planktic foraminiferal stable isotope records in this region to span MIS 7, which, together with data from

  20. Variability of oceanic carbon cycle in the North Pacific from seasonal to decadal scales

    NASA Astrophysics Data System (ADS)

    Xiu, Peng; Chai, Fei

    2014-08-01

    Variability of upper-ocean carbon cycle in the North Pacific during 1958-2010 period is investigated using a physical-biogeochemical model. Comparisons with in situ data from five different oceanographic environments in the South China Sea, Monterey Bay, North Pacific gyre, northwestern Pacific, and Gulf of Alaska indicate that the model usually captures observed seasonal and interannual variability in both sea surface pCO2 and sea-air CO2 flux. Seasonal variability of pCO2 and CO2 flux in the North Pacific follows the change in sea surface temperature (SST) closely with high and low values in summer and winter, respectively. Total CO2 modifies pCO2 seasonal pattern in an opposite manner with respect to SST, and surface wind speed modifies the magnitude of CO2 flux variations. On interannual and decadal time scales, sea surface pCO2 is primarily controlled by anthropogenic CO2, followed by modulations by the El Niño-Southern Oscillation and the Pacific Decadal Oscillation (PDO), while sea-air CO2 flux is significantly regulated by the PDO and the North Pacific Gyre Oscillation (NPGO). We show that anthropogenic CO2 tends to amplify the influence on CO2 flux from the PDO but to damp the influence from the NPGO.

  1. Interannual Variability of the Asian Summer Monsoon: Contrasts between the Indian and the Western North Pacific-East Asian Monsoons(.

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Wu, Renguang; Lau, K.-M.

    2001-10-01

    Analyses of 50-yr NCEP-NCAR reanalysis data reveal remarkably different interannual variability between the Indian summer monsoon (ISM) and western North Pacific summer monsoon (WNPSM) in their temporal-spatial structures, relationships to El Niño, and teleconnections with midlatitude circulations. Thus, two circulation indices are necessary, which measure the variability of the ISM and WNPSM, respectively. A weak WNPSM features suppressed convection along 10°-20°N and enhanced rainfall along the mei-yu/baiu front. So the WNPSM index also provides a measure for the east Asian summer monsoon. An anomalous WNPSM exhibits a prominent meridional coupling among the Australian high, cross-equatorial flows, WNP monsoon trough, WNP subtropical high, east Asian subtropical front, and Okhotsk high. The WNP monsoon has leading spectral peaks at 50 and 16 months, whereas the Indian monsoon displays a primary peak around 30 months. The WNPSM is weak during the decay of an El Niño, whereas the ISM tends to abate when an El Niño develops. Since the late 1970s, the WNPSM has become more variable, but its relationship with El Niño remained steady; in contrast, the ISM has become less variable and its linkage with El Niño has dramatically declined. These contrasting features are in part attributed to the differing processes of monsoon-ocean interaction.Also found is a teleconnection between a suppressed WNPSM and deficient summer rainfall over the Great Plains of the United States. This boreal summer teleconnection is forced by the heat source fluctuation associated with the WNPSM and appears to be established through excitation of Rossby wave trains and perturbation of the jet stream that further excites downstream optimum unstable modes.

  2. 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

  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. Evaluating the opposing wave interaction hypothesis for the generation of microbaroms in the eastern North Pacific

    NASA Astrophysics Data System (ADS)

    Walker, Kristoffer T.

    2012-12-01

    Two microphone arrays were deployed in California during 2010 to record microbaroms, quasi-continuous atmospheric pressure oscillations with a period of ˜5 s. In this paper a time-progressive, frequency domain beamforming method is developed and used to analyze microbaroms recorded by these and 10 other infrasonic arrays along the North Pacific rim. Common pelagic microbarom sources that move around the North Pacific are observed during the boreal winter. Summertime North Pacific sources are only observed by western Pacific arrays, presumably a result of weaker microbarom radiation and westward stratospheric winds. A well-defined source is resolved ˜2000 km off the coast of California in January 2011 that moves closer to land over several days. The source locations are corrected for deflection by horizontal winds using acoustic ray trace modeling with range-dependent atmospheric specifications provided by ground-to-space models. The observed source locations do not correlate with anomalies in NOAA Wave Watch 3 (NWW3) model field data. However, application of the opposing wave, microbarom source model of Waxler and Gilbert (2006) to the NWW3 directional wave height spectra output at buoy locations within 1100 km of the western North America coastline predicts microbarom radiation in locations that correlate with observed locations. These results suggest that pelagic North Pacific microbarom radiation detected by infrasonic arrays during the boreal winter could be routinely used to validate NWW3 results in regions with poor sensor coverage.

  5. The role and production of polar/subtropical jet superpositions in two high-impact weather events over North America

    NASA Astrophysics Data System (ADS)

    Winters, Andrew C.

    Careful observational work has demonstrated that the tropopause is typically characterized by a three-step pole-to-equator structure, with each break between steps in the tropopause height associated with a jet stream. While the two jet streams, the polar and subtropical jets, typically occupy different latitude bands, their separation can occasionally vanish, resulting in a vertical superposition of the two jets. A cursory examination of a number of historical and recent high-impact weather events over North America and the North Atlantic indicates that superposed jets can be an important component of their evolution. Consequently, this dissertation examines two recent jet superposition cases, the 18--20 December 2009 Mid-Atlantic Blizzard and the 1--3 May 2010 Nashville Flood, in an effort (1) to determine the specific influence that a superposed jet can have on the development of a high-impact weather event and (2) to illuminate the processes that facilitated the production of a superposition in each case. An examination of these cases from a basic-state variable and PV inversion perspective demonstrates that elements of both the remote and local synoptic environment are important to consider while diagnosing the development of a jet superposition. Specifically, the process of jet superposition begins with the remote production of a cyclonic (anticyclonic) tropopause disturbance at high (low) latitudes. The cyclonic circulation typically originates at polar latitudes, while organized tropical convection can encourage the development of an anticyclonic circulation anomaly within the tropical upper-troposphere. The concurrent advection of both anomalies towards middle latitudes subsequently allows their individual circulations to laterally displace the location of the individual tropopause breaks. Once the two circulation anomalies position the polar and subtropical tropopause breaks in close proximity to one another, elements within the local environment, such as

  6. Age Dependent 3-D Magnetic Modeling of the North Pacific and North Atlantic Oceanic Crust at Intermediate Wavelengths

    NASA Technical Reports Server (NTRS)

    Yanez, Gonzalo A.; LaBrecque, John L.

    1996-01-01

    Three-dimensional magnetic modeling of the North Atlantic and Northeast pacific is performed at intermediate wavelengths using three models for the acquisition of a natural remanent magnetization. It is shown that a remanent magnetization which is dependent on the rustal age is the dominant source for the intermediate wavelength pattern in both basins.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  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. 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

  15. Paleotemperature and paleosalinity inferences and chemostratigraphy across the Aptian/Albian boundary in the subtropical North Atlantic

    NASA Astrophysics Data System (ADS)

    Huber, Brian T.; MacLeod, Kenneth G.; GröCke, Darren R.; Kucera, Michal

    2011-12-01

    Geochemical analyses of extraordinarily well preserved late Aptian-early Albian foraminifera from Blake Nose (Ocean Drilling Program Site 1049) reveal rapid shifts of δ18O, δ13C, and 87Sr/88Sr in the subtropical North Atlantic that may be linked to a major planktic foraminifer extinction event across the Aptian/Albian boundary. The abruptness of the observed geochemical shifts and their coincidence with a sharp lithologic contact is explained as an artifact of a previously undetected hiatus of 0.8-1.4 million years at the boundary contact, but the values before and after the hiatus indicate that major oceanographic changes occurred at this time. 87Sr/88Sr increase by ˜0.000 200, δ13C values decrease by 1.5‰ to 2.2‰, and δ18O values decrease by ˜1.0‰ (planktics) to 0.5‰ (benthics) across the hiatus. Further, both 87Sr/88Sr ratios and δ18O values during the Albian are anomalously high. The 87Sr/88Sr values deviate from known patterns to such a degree that an explanation requires either the presence of inter-basin differences in seawater 87Sr/88Sr during the Albian or revision of the seawater curve. For δ18O, planktic values in some Aptian samples likely reflect a diagenetic overprint, but preservation is excellent in the rest of the section. In well preserved material, benthic foraminiferal values are largely between 0.5 and 0.0‰ and planktic samples are largely between 0.0‰ to -1.0‰, with a brief excursion to -2.0‰ during OAE 1b. Using standard assumptions for Cretaceous isotopic paleotemperature calculations, the δ18O values suggest bottom water temperatures (at ˜1000 -1500 m) of 8-10°C and surface temperatures of 10-14°C, which are 4-6°C and 10-16°C cooler, respectively, than present-day conditions at the same latitude. The cool subtropical sea surface temperature estimates are especially problematic because other paleoclimate proxy data for the mid-Cretaceous and climate model predictions suggest that subtropical sea surface

  16. Organic nutrients and excess nitrogen in the North Atlantic subtropical gyre

    NASA Astrophysics Data System (ADS)

    Landolfi, A.; Oschlies, A.; Sanders, R.

    2008-02-01

    To enable an accurate estimate of total excess nitrogen (N) in the North Atlantic a new tracer, TNxs, is defined which includes the contribution of organic nutrients to the assessment of N:P stoichiometric anomalies. We estimate the spatial distribution of TNxs within the North Atlantic using data from a trans-Atlantic section across 24.5° N conducted in 2004. We then employ three different approaches to infer rates of total excess nitrogen accumulation using pCFC-12 derived ventilation ages (a TNxs vertical integration, a one end-member and a two-end member mixing model). Despite some variability among the different methods the dissolved organic nutrient fraction always contributes to about half of the TNxs accumulation, which is in the order of 9.38±4.18×1011 mol N y-1. Here we suggest that neglecting organic nutrients in stoichiometric balances of the marine N and P inventories can lead to systematic errors when estimating a nitrogen excess or deficit relative to the Redfield ratio in the oceans. For the North Atlantic the inclusion of the organic fraction leads to an upward revision of the N supply by N2 fixation to 10.2±6.9×1011 mol N y-1. This enhanced estimate of nitrogen fixation reconciles the geochemical estimates of N2 fixation derived from excess nitrate and the direct estimates from N2 fixation measurements.

  17. 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

  18. 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.

  19. 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.

  20. The spring relationship between the Pacific-North American pattern and the North Atlantic Oscillation

    NASA Astrophysics Data System (ADS)

    Soulard, Nicholas; Lin, Hai

    2016-03-01

    The Pacific-North American pattern (PNA) and North Atlantic Oscillation (NAO) are two dominant modes of low-frequency variability in the Northern Hemisphere winter. Generally these two patterns are separable and uncorrelated in both space and time. However, dating back to the 1970s there have been studies which have linked the Aleutian and Icelandic low intensities, and shown that a significant temporal correlation does, on occasion, occur. Each of these semi-permanent low pressure systems is a part of the PNA and NAO patterns, respectively, and therefore, given a link between the two semi-permanent low pressure systems, we explore whether a link between the PNA and NAO also appears. Recently studies have found such a link during the winters of certain decades. The present study, documents an observed relationship between the PNA and NAO which is consistently present during the spring and early summer. This relationship is shown to be due to the fact that the PNA and NAO are spatially overlapping projections of the same pattern of variability, given by the first EOF of 500 hPa geopotential height. Both the PNA and NAO patterns correlate more strongly to the first EOF's spatial pattern, resembling the Aleutian low-Icelandic low seesaw pattern, than the rotated EOF (REOF) loading patterns used to compute their respective indices. Furthermore, when the two patterns are correlated, the effect of El-Nino on the Northern Hemisphere is separate from the pattern associated with the PNA. Finally, we examine a 21-year period in the winter for which the PNA and NAO are significantly correlated, and find that the conclusions drawn from the spring hold true. The results presented herein demonstrate that defining the PNA and NAO based upon typical loading patterns may not be the ideal approach; especially given that the patterns are spatially similar and covary in time.

  1. 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

  2. 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.

  3. 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

  4. 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

  5. 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.

  6. 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

  7. Invasive range expansion by the Humboldt squid, Dosidicus gigas, in the eastern North Pacific.

    PubMed

    Zeidberg, Louis D; Robison, Bruce H

    2007-07-31

    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. Reconstructing dust input to the Subarctic North Pacific - Past and Present

    NASA Astrophysics Data System (ADS)

    Winckler, G.; Serno, S.; Anderson, R. F.; Hayes, C. T.; Gersonde, R.; Haug, G. H.

    2011-12-01

    The Subarctic North Pacific constitutes one of the high-nutrient-low chlorophyll (HNLC) regions of the modern ocean, where the biological pump is relatively inefficient at transferring carbon from the atmosphere to the deep sea. Iron limitation is traditionally suggested as the main controlling factor of biological production/the HNLC status of the Subarctic North Pacific, with iron thought to be primarily delivered by atmospheric dust transport from the East Asian desert areas. However, our understanding of the links between dust, biological production and climate is hampered by the lack of reliable dust flux records in the Subarctic North Pacific as well as longstanding discrepancies among specific techniques that have been used in previous research to reconstruct biological productivity. The lack of reliable dust flux reconstructions from North Pacific sediments is due a variety of reasons, among them sparsity of sediment cores, uncertain age control of the sediments as well as the impact of sediment input other than dust, such as hemipelagic and volcanic material as well as ice-rafted debris. Here, we map and compare spatial patterns of two proxies of eolian dust fluxes (230Thxs-normalized 232Th and 4He fluxes) as well as REE elements (e.g., La/Yb and Th/Sc ratios to deconvolve eolian and volcanic input to the sediments) from 37 multicore core-top sediments across the Subarctic North Pacific, obtained during the INOPEX cruise in 2009. We will present spatial patterns of these tracers to test their validity as proxies of mineral dust and to deconvolve dust and volcanic input to the sediments. The spatial patterns of the reconstructed dust fluxes will be compared to results of published reconstructions of modern dust trajectories to test the validity of these methods to capture modern dust flux patterns to the Subarctic North Pacific. The results from this study will be used for future research focusing on dust flux and productivity changes during the abrupt

  9. 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

  10. 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

  11. Transport of desert dust mixed with North African industrial pollutants in the subtropical Saharan Air Layer

    NASA Astrophysics Data System (ADS)

    Rodríguez, S.; Alastuey, A.; Alonso-Pérez, S.; Querol, X.; Cuevas, E.; Abreu-Afonso, J.; Viana, M.; Pérez, N.; Pandolfi, M.; de La Rosa, J.

    2011-07-01

    An analysis of chemical composition data of particulate matter samples (TSP, PM10 and PM2.5) collected from 2002 to 2008 in the North Atlantic free troposphere at the Izaña Global Atmospheric Watch (GAW) observatory (Tenerife, Canary Islands) shows that desert dust is very frequently mixed with particulate pollutants in the Saharan Air Layer (SAL). The study of this data set with Median Concentrations At Receptor (MCAR) plots allowed the identification of the potential source regions of the dust and particulate pollutants. Areas located at the south of the southern slope of the Atlas mountains emerge as the most frequent source of the soil desert dust advected to the northern edge of the SAL in summer. Industrial emissions occurring in Northern Algeria, Eastern Algeria, Tunisia and the Atlantic coast of Morocco appear as the most important source of the nitrate, ammonium and a fraction of sulphate (at least 60 % of the sulphate <10 μm transported from some regions) observed in the SAL. These emissions are mostly linked to crude oil refineries, phosphate-based fertilizer industry and power plants. Although desert dust emissions appear as the most frequent source of the phosphorous observed in the SAL, high P concentrations are observed when the SAL is affected by emissions from open mines of phosphate and phosphate based fertilizer industry. The results also show that a significant fraction of the sulphate (up to 90 % of sulphate <10 μm transported from some regions) observed in the SAL may be influenced by soil emissions of evaporite minerals in well defined regions where dry saline lakes (chotts) are present. These interpretations of the MCAR plots are consistent with the results obtained with the Positive Matrix Factorization (PMF2) receptor modelling. The results of this study show that North African industrial pollutants may be mixed with desert dust and exported to the North Atlantic in the Saharan Air Layer.

  12. Transport of desert dust mixed with North African industrial pollutants in the subtropical Saharan Air Layer

    NASA Astrophysics Data System (ADS)

    Rodríguez, S.; Alastuey, A.; Alonso-Pérez, S.; Querol, X.; Cuevas, E.; Abreu-Afonso, J.; Viana, M.; Pandolfi, M.; de La Rosa, J.

    2011-03-01

    The chemical composition of particulate matter samples (TSP, PM10 and PM2.5) collected from 2002 to 2008 in the North Atlantic free troposphere at Izaña Global Atmospheric Watch (GAW) observatory (Tenerife, The Canary Islands) was studied. The analysis of the samples collected in the Saharan Air Layer (SAL) shows that soil desert dust is very frequently mixed with particulate pollutants. An analysis of this data set with Median Concentrations At Receptor (MCAR) plots allowed to identify the potential source regions of the dust and particulate pollutants. Areas located at the south of the Southern slope of Atlas emerge as the most frequent source of the soil desert dust advected to the northern edge of the SAL in summer. Industrial emissions occurring along the Atlantic coast of Morocco, Northern Algeria, Eastern Algeria and Tunisia appear as the most important source of the nitrate, ammonium and a fraction of sulphate (at least a 60% of the sulphate <10 μm transported from some regions) observed in the SAL. These emissions are mostly linked to crude oil refineries, phosphate-based fertilizer industry and power plants. Although desert dust emissions appear as the most frequent source of the phosphorous observed in the SAL, high P concentrations are observed when the SAL is affected by emissions from open mines of phosphate and phosphate based fertilizer industry. The results also show that a significant fraction of the sulphate (up to 90% of sulphate <10 μm transported from some regions) observed in the SAL is linked to soil emissions of evaporite minerals in well defined regions where dry saline lakes (chotts) are present. These interpretations of the MCAR plots are consistent with the results obtained with the Positive Matrix Factorization receptor modelling. The results of this study show that North African industrial pollutants may be mixed with desert dust and exported to the North Atlantic in the Saharan Air Layer.

  13. Heterotrophic bacterial production and extracellular enzymatic activity in sinking particulate matter in the western North Pacific Ocean

    PubMed Central

    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 (HBPSW) and SPM (HBPSPM) 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 HBPSW from the surface to 500 m was comparable between the locations, whereas HBPSPM 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. New Carbon Source From Microbial Degradation of Pre-Production Resin Pellets from the North Pacific Gyre

    NASA Astrophysics Data System (ADS)

    Neal, A.; Mielke, R.; Stam, C. N.; Gonsior, M.; Tsapin, A. I.; Lee, G.; Leftwich, B.; Narayan, R.; Coleman, H.; Argyropoulos, N.; Sheavly, S. B.; Gorby, Y. A.

    2011-12-01

    Numerous pollutants are transported through the world's oceans that impact oceanic health. Diffuse sources include land-based runoff, atmospheric depositions, shipping industry wastes, and others. Synthetic polymer marine debris is a multi-faceted problem that includes interactions with environmental toxins, carbon cycling systems, ocean surface chemistry, fine minerals deposition, and nano-particles. The impact that synthetic polymer-microbe interactions have on carbon input into the open ocean is poorly understood. Here we demonstrate that both biotic and abiotic processes contribute to degradation of pre-production resin pellets (PRPs), in open ocean environments and new methodologies to determine carbon loss from this synthetic polymer debris. Our data shows that material degradation of environmental polyethylene PRPs can potentially deposit 13 mg/g to 65 mg/g of carbon per PRP into our marine environments. Environmental pre-production resin pellets were collected on the S/V Kaisei cruise in 2009 which covered over 3,000 nautical miles and sampled over 102,000 m3 of the first 15cm of the water column in the Subtropical Convergence Zone of the North Pacific Gyre. Environmental PRP degradation and the role microbial communities play in this was evaluated using a combination of Fourier transform infrared spectroscopy, environmental scanning electron microscopy, scanning transmission electron microscopy, X-ray microtomography, and ArcGIS mapping. More research is needed to understand the environmental impact of this new carbon source arising from synthetic polymers as they degrade in oceanic environments.

  15. 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.

  16. Recent metalliferous sediment in the North Pacific manganese nodule area

    USGS Publications Warehouse

    Bischoff, J.L.; Rosenbauer, R.J.

    1977-01-01

    Quaternary sediments cored in the northeast Pacific nodule area (DOMES site C, 14??N, 126??W) contain a significant amount of hydrothermal metalliferous mud. Water content, color, mineralogy, and chemical composition are analogous to metalliferous sediments of the subequatorial East Pacific Rise. Correction for contribution of pelagic clay indicates the metalliferous fraction to be about 40% of the sediment. SiO2 and Mg are major components in the corrected composition, as they are for other metalliferous sediments similarly corrected from a variety of East Pacific Rise and DSDP metalliferous sediments. A correlation between Mg and SiO2 for these corrected sediments could indicate a hydrothermal origin for a significant portion of the SiO2. Results from DSDP in the nodule area suggest that metalliferous globules are a ubiquitous minor component of the Clipperton Oceanic Formation, which underlies much of the Pacific ferromanganese nodule belt. This indicates that deposition of hydrothermal precipitates is not confined to spreading centers. ?? 1977.

  17. 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.

  18. 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).

  19. 75 FR 70903 - Eastern North Pacific Gray Whale; Notice of Extension of Public Comment Period on Marine Mammal...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-19

    ... on the petition (75 FR 68756). That Federal Register notice began NMFS' 15-day public comment period... National Oceanic and Atmospheric Administration RIN 0648-XA018 Eastern North Pacific Gray Whale; Notice of... petition to designate the Eastern North Pacific population of gray whales (Eschrichtius robustus) as...

  20. 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.

  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. Variability of the Heat and Salt Budget in the Subtropical South-Eastern Pacific Mixed Layer between 2004 and 2010: Spice Injection Mechanism

    NASA Astrophysics Data System (ADS)

    Kolodziejczyk, Nicolas; Gaillard, Fabienne

    2013-04-01

    The mixed layer heat and salt budget in the southeastern subtropical Pacific is estimated using 7 years (2004-2010) of Argo profiling float data, surface fluxes, precipitation, surface velocity data and wind stress observations and reanalysis. In this region the mixed layer heat budget is characterized by a strong annual cycle mainly modulated by the shortwave radiation annual cycle. During the austral fall and winter the shortwave radiation input minimum is overwhelmed by the heat loss mainly due to the latent heat flux. The mixed layer salt budget presents also a strong annual cycle with a minimum of salt content during the late austral winter. In contrast with the heat budget, the salt budget is mainly driven by the unresolved terms computed as the residual of the budget. Among these missing terms, the most likely candidate is the vertical eddy mixing due to convection caused by the heat surface buoyancy loss and the destabilizing vertical gradient of salinity at the base of the mixed layer. This downward flux of salt at the base of the mixed layer could explain the annual spiciness injection and interannual spiciness variability in the permanent thermocline in the southeastern Pacific.

  3. Tropical forcing of the North Pacific climate shift in the 1920s

    NASA Astrophysics Data System (ADS)

    Tokinaga, H.

    2015-12-01

    The North Pacific climate has undergone interdecadal regime shifts during the twentieth century, such as in the mid-1920s, the mid-1970s, and the late-1990s. These climate shifts are closely related to phase changes in the Pacific Decadal Oscillation. A strong linkage between changes in the tropical Pacific SST and the Aleutian low is evident in the 1970s and 1990s climate shifts but has remained unclear in the 1920s due to limited in situ observations in the tropical Pacific. We revisit the tropical influence on the North Pacific climate shift in the 1920s by utilizing an atmospheric general circulation model (AGCM) and a series of new historical climate data sets that incorporate the updated data source of in situ observations not available in the conventional climate data sets. New SST data sets such as COBE-SST2 improve data coverage in the tropical Pacific during the early twentieth century compared with their previous versions. These new SST data sets exhibit a pronounced equatorial Pacific warming in the mid-1920s, consistent with observed weakening of the equatorial trade winds and the zonal SLP gradient between the tropical Pacific and Indian Ocean. This feature cannot be captured in conventional SST data sets such as HadISST1 and COBE-SST1. An AGCM forced by the new SST data sets successfully simulate not only the weakening of the Walker circulation but also a significant deepening of the Aleutian low observed in the mid-1920s. TOGA experiments suggest that the SST warming in the tropical Pacific is key to strengthen the Aleutian low as observed in the mid-1970s regime shift.

  4. North Atlantic subpolar and subtropical gyres variability during the last 2000 years: a contribution to the THOR project.

    NASA Astrophysics Data System (ADS)

    Bouinot, Thomas; Cortijo, Elsa; Govin, Aline; Mulder, Thierry; Gonthier, Eliane

    2010-05-01

    Recent oceanographic measurements showed that the Atlantic Meridional Overturning Circulation (AMOC) underwent fluctuations in decadal period of time over the past. The causes of these fluctuations are still poorly understood, and available observations are too limited in time (few decades only) to investigate the detailed mechanisms. The Gulf Stream (GS), which actively transports heat from low to high latitudes, mainly in the first few hundred meters of the water column, could play an important role in the natural variability of the AMOC. This study aims at better constraining the variability of North Atlantic surface and subsurface waters over the last 2000 years, in order to improve our understanding of the links between AMOC oscillations and variations in the upper Atlantic heat content. This work is part of the European THOR (Thermohaline Overturning - at Risk?) project. Three cores are considered in key areas of the North Atlantic: (1) IMAGES core MD08-3182 (52°41.99'N, 35°56.15'W, 3757m) is located in the main pathway of the Gulf Stream in the Charlie Gibbs Fracture Zone, a key location for monitoring the subpolar gyre dynamics. (2) IMAGES core MD99-2203 (34°58.38N, 75°12.06'W-620m) off Cape Hatteras is well located to record the past variability of the GS. (3) Core CADI2KS12 (36°42.79'N, 08°31.39'W-1120m), from the Gulf of Cádiz, monitors the return current of the subtropical gyre. All cores are radiocarbon dated by AMS. In each core, the upper water column characteristics are reconstructed by complementary geochemical analysis: paired measurements of oxygen isotopic composition and trace elements ratio (Mg/Ca) in planktonic foraminifera are combined to reconstruct the seawater temperature and oxygen isotopic composition. Both surface and deep-dwelling species are considered to obtain temperature and oxygen isotopic composition records of the first few hundred meters of the water column. We will present our first results of the variability of the

  5. Oceanographic characteristics of biological hot spots in the North Pacific: A remote sensing perspective

    NASA Astrophysics Data System (ADS)

    Palacios, Daniel M.; Bograd, Steven J.; Foley, David G.; Schwing, Franklin B.

    2006-02-01

    Biological hot spots in the ocean are likely created by physical processes and have distinct oceanographic signatures. Marine predators, including large pelagic fish, marine mammals, seabirds, and fishing vessels, recognize that prey organisms congregate at ocean fronts, eddies, and other physical features. Here we use remote sensing observations from multiple satellite platforms to characterize physical oceanographic processes in four regions of the North Pacific Ocean that are recognized as biological hot spots. We use data from the central North Pacific, the northeastern tropical Pacific, the California Current System, and the Galápagos Islands to identify and quantify dynamic features in terms of spatial scale, degree of persistence or recurrence, forcing mechanism, and biological impact. The dominant timescales of these processes vary from interannual (Rossby wave interactions in the central North Pacific) to annual (spring-summer intensification of alongshore winds in the California Current System; winter wind outflow events through mountain gaps into the northeastern tropical Pacific), to intraseasonal (high-frequency equatorial waves at the Galápagos). Satellite oceanographic monitoring, combined with data from large-scale electronic tagging experiments, can be used to conduct a census of biological hot spots, to understand behavioral changes and species interactions within hot spots, and to differentiate the preferred pelagic habitats of different species. The identification and monitoring of biological hot spots could constitute an effective approach to marine conservation and resource management.

  6. 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

  7. 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...

  8. Mechanisms and predictability of multiyear ecosystem variability in the North Pacific

    NASA Astrophysics Data System (ADS)

    Chikamoto, Megumi O.; Timmermann, Axel; Chikamoto, Yoshimitsu; Tokinaga, Hiroki; Harada, Naomi

    2015-11-01

    Aleutian Low variations provide vorticity, buoyancy, and heat-flux forcing to the North Pacific Ocean, which in turn cause changes in ocean circulation, mixed layer characteristics and sea ice coverage. In this process the white noise atmospheric characteristics are integrated dynamically and thermodynamically to generate red noise ocean spectra. Using the Community Earth System Model (version 1.0.3) we study the resulting biogeochemical and ecosystem responses in the North Pacific. We find that ocean dynamical variables have an impact on the tendencies of key nutrients and biological production, which leads to a further reddening of biogeochemical spectra resulting in potential predictability on time scales of 2-4 years. However, this low-pass filtering does not apply to all biogeochemical variables and is regionally dependent. It is shown that phytoplankton biomass in the Central North Pacific adjusts to the much shorter-term variability associated with changes in mixed layer depth, light availability, and zooplankton grazing, thus limiting the predictability of phytoplankton anomalies to about 1 year. In the eastern North Pacific the slow advection of anomalous nutrient concentrations leads to longer persistence of phytoplankton variability and increased potential predictability of up to 3 years.

  9. Pacific/North American teleconnection controls on precipitation isotope ratios across the contiguous United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Large-scale climate teleconnections such as the Pacific/North American (PNA) pattern stronglyinfluence atmospheric processes and continental climate. Here we show that precipitation deltaO-18 values in the contiguous United States are correlated with an index of the PNA pattern. The deltaO-18/PNA re...

  10. 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...

  11. 77 FR 41972 - North Pacific Fishery Management Council (NPFMC); Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-17

    ... scoping period for the Steller Sea Lion Protection Measures EIS (77 FR 22750, April 17, 2012). Information... National Oceanic and Atmospheric Administration North Pacific Fishery Management Council (NPFMC); Public... Management Council's (Council) Steller Sea Lion Mitigation Committee (SSLMC) will meet in Seattle, WA....

  12. High mortality of Pacific oysters in a cold winter in the North-Frisian Wadden Sea

    NASA Astrophysics Data System (ADS)

    Büttger, Heike; Nehls, Georg; Witte, Sophia

    2011-12-01

    Mortality of introduced Pacific oysters ( Crassostrea gigas) was studied in the northern Wadden Sea in response to an ice winter. After a decade of mild winters, in January and February 2010, the first severe winter occurred since the Pacific oysters became dominant on former intertidal blue mussel ( Mytilus edulis) beds in the North-Frisian Wadden Sea. After the ice winter, mortality of Pacific oysters on densely populated beds in the List tidal basin reached about 90%, indicating much higher losses in comparison to former mild winters. At lower densities between the islands of Amrum and Föhr, oysters were less or even not affected. Although Pacific oysters are assumed to be very tolerant to frost, the duration of cold water- and air temperatures accompanied by mechanical stress of the ice burden might have caused the high mortality in the winter 2009/2010 in formerly dense beds.

  13. 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.

  14. Characterization of the Marine Boundary Layer and the Trade-Wind Inversion over the Sub-tropical North Atlantic

    NASA Astrophysics Data System (ADS)

    Carrillo, J.; Guerra, J. C.; Cuevas, E.; Barrancos, J.

    2016-02-01

    The stability of the lower troposphere along the east side of the sub-tropical North Atlantic is analyzed and characterized using upper air meteorological long-term records at the Canary Islands (Tenerife), Madeira (Madeira) and Azores (Terceira) archipelagos. The most remarkable characteristic is the strong stratification observed in the lower troposphere, with a strengthening of stability centred at levels near 900 and 800 hPa in a significant percentage of soundings (ranging from 17 % in Azores to 33 % in Güimar, Canary Islands). We show that this double structure is associated with the top of the marine boundary layer (MBL) and the trade-wind inversion (TWI) respectively. The top of the MBL coincides with the base of the first temperature inversion (≈ 900 hPa) where a sharp change in water vapour mixing ratio is observed. A second temperature inversion is found near 800 hPa, which is characterized by a large directional wind shear just above the inversion layer, tied to the TWI. We find that seasonal and latitudinal variations of the height and strength of both temperature inversions are driven by large-scale subsiding air from the upper troposphere associated with the descent branch of the Hadley cell. Increased general subsidence in summertime enhances stability in the lower troposphere, more markedly in the southern stations, where the inversion-layer heights are found at lower levels enhancing the main features of these two temperature inversions. A simple conceptual model that explains the lower tropospheric inversion enhancement by subsidence is proposed.

  15. Climatology of new particle formation events in the subtropical North Atlantic free troposphere at Izaña GAW observatory

    NASA Astrophysics Data System (ADS)

    García, M. I.; Rodríguez, S.; González, Y.; García, R. D.

    2013-09-01

    A climatology of new particle formation (NPF) events in the subtropical North Atlantic free troposphere is presented. A four year data set (June 2008-June 2012), which includes number size distributions (10-600 nm), reactive gases (SO2, NOx, and O3), several components of solar radiation and meteorological parameters, measured at Izaña Global Atmospheric Watch observatory (2400 m above sea level; Tenerife, Canary Islands) was analysed. On average, NPF occurred during 30% of the days,the mean values of the formation and growth rates during the study period were 0.49 cm-3 s-1 and 0.42 nm h-1, correspondingly. There is a clearly marked NPF season (May to August), when these events account for 50 to 60% of the days/month. Monthly mean values of the formation and growth rates exhibit higher values during this season (0.50-0.95 cm-3 s-1 and 0.48-0.58 nm h-1, respectively) than during other periods. The two steps (formation and growth) of the NPF process mostly occur under the prevailing northern winds typical of this region. Sulphur dioxide and UV radiation show higher levels during NPF events than in other type of episodes. The presence of Saharan dust in the free troposphere is associated with a decrease in the formation rates of new particles. In the analysis of the year-to-year variability, mean sulphur dioxide concentration (within the range 60-300 ppt) was the parameter that exhibited the highest correlation with the frequency of NPF episodes. The availability of this trace gas (i.e. their oxidation products) seems also to have a influence on the duration of the events, number of formed nucleation particles, formation rates and growth rates. We identified a set of NPF events in which two nucleation modes (that may evolve at different rates) occur simultaneously and for which further investigations are necessary.

  16. Argo data assimilation and its effect on climate state estimation and forecasting in the western North Pacific using a coupled model

    NASA Astrophysics Data System (ADS)

    Nishikawa, Shiro; Ishikawa, Yoichi; Masuda, Shuhei; Hiyoshi, Yoshihisa; Sasaki, Yuji; Igarashi, Hiromichi

    2015-04-01

    In this study, we investigated the effects of ocean subsurface data (Argo data) on climate state estimation and forecasting, focusing on the reproduction of North Pacific subtropical mode water (STMW) using a four-dimensional variational data assimilation system with a coupled model. We produced two reanalysis plus forecast data sets for the ocean and atmosphere in 2010 using a 3 month assimilation period: the first including Argo data (Argo case) and the second did not include Argo data (control case). In the control case, the Kuroshio, Kuroshio Extension front, and recirculation gyres along the front were not adequately reproduced. Consequently, there were large biases in temperature and salinity in the western North Pacific. The assimilation of Argo data effectively corrected these biases and significantly improved reproduction of the Kuroshio fronts and recirculation gyres, resulting in a more realistic reproduction of the winter mixed layer and STMW. The correction of these biases is critical to the 1-3 year predictions of the STMW core properties, and the assimilation of Argo data enables prediction of these properties for more than a year. We showed that assimilation of Argo data affects the surface atmospheric temperature above the STMW formation region.

  17. 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.

  18. 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.

  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. Contribution of the North Atlantic Subtropical High to Regional Climate Model (RCM) Skill in Simulating Southeastern United States Summer Precipitation

    NASA Astrophysics Data System (ADS)

    Li, L.; Li, W.; Jin, J.

    2014-12-01

    This study assesses the skill of advanced regional climate models (RCMs) in simulating Southeastern United States (SE US) summer precipitation and explores the mechanisms responsible for the simulation skill at a process level. Analysis of the RCM output for the North American Regional Climate Change Assessment Program (NARCCAP) indicates that the RCM simulations of summer precipitation show large biases and a remarkable spread over the SE US. The causes of such a spread are investigated by performing simulations using the Weather Research and Forecasting (WRF) model, a next-generation RCM developed by the US National Center for Atmospheric Research. The results show that the simulated biases in SE US summer precipitation are due mainly to the misrepresentation of the modeled North Atlantic Subtropical High (NASH) western ridge. In WRF simulations, the NASH western ridge shifts 7-deg northwestward compared to that in the reanalysis ensemble, leading to a dry bias in the simulated precipitation according to the "NASH western ridge - Southeast summer precipitation" relationship. Experiments utilizing the Four Dimensional Data Assimilation technique further suggest that the improved representation of the circulation patterns associated with the NASH western ridge substantially reduces the bias in simulating SE US summer precipitation. Our analysis of circulation dynamics indicates that the NASH western ridge in the WRF simulations is significantly influenced by planetary boundary layer (PBL) processes over the Gulf of Mexico. Specifically, a decrease (increase) in the simulated PBL height tends to stabilize (destabilize) the lower troposphere over the Gulf of Mexico, and thus inhibits (favors) the onset and/or development of convection. The changes in tropical convecton induce a tropical-extratropical teleconnection pattern, which modulates the circulation along the NASH western ridge in the WRF simulations and contributes to the precipitation biases over the SE US

  2. Contribution of the North Atlantic subtropical high to regional climate model (RCM) skill in simulating southeastern United States summer precipitation

    NASA Astrophysics Data System (ADS)

    Li, Laifang; Li, Wenhong; Jin, Jiming

    2015-07-01

    This study assesses the skill of advanced regional climate models (RCMs) in simulating southeastern United States (SE US) summer precipitation and explores the physical mechanisms responsible for the simulation skill at a process level. Analysis of the RCM output for the North American Regional Climate Change Assessment Program indicates that the RCM simulations of summer precipitation show the largest biases and a remarkable spread over the SE US compared to other regions in the contiguous US. The causes of such a spread are investigated by performing simulations using the Weather Research and Forecasting (WRF) model, a next-generation RCM developed by the US National Center for Atmospheric Research. The results show that the simulated biases in SE US summer precipitation are due mainly to the misrepresentation of the modeled North Atlantic subtropical high (NASH) western ridge. In the WRF simulations, the NASH western ridge shifts 7° northwestward when compared to that in the reanalysis ensemble, leading to a dry bias in the simulated summer precipitation according to the relationship between the NASH western ridge and summer precipitation over the southeast. Experiments utilizing the four dimensional data assimilation technique further suggest that the improved representation of the circulation patterns (i.e., wind fields) associated with the NASH western ridge substantially reduces the bias in the simulated SE US summer precipitation. Our analysis of circulation dynamics indicates that the NASH western ridge in the WRF simulations is significantly influenced by the simulated planetary boundary layer (PBL) processes over the Gulf of Mexico. Specifically, a decrease (increase) in the simulated PBL height tends to stabilize (destabilize) the lower troposphere over the Gulf of Mexico, and thus inhibits (favors) the onset and/or development of convection. Such changes in tropical convection induce a tropical-extratropical teleconnection pattern, which modulates the

  3. Sear surface salinity variability in subtropical North Atlantic from Aquarius satellite mission and historical in-situ data

    NASA Astrophysics Data System (ADS)

    Melnichenko, O.; Maximenko, N. A.; Hacker, P. W.; Potemra, J. T.

    2012-12-01

    Sea surface salinity (SSS) variability in the North Atlantic is studied using the first year of Aquarius observations and historical thermosalinograph (TSG) data, collected by the Global Ocean Surface Underway Data Pilot Project (GOSUD). The particular focus of this study is on the subtropical maximum of SSS, where the Salinity Processes in the Upper Ocean Regional Study (SPURS) experiment is about to start. Spatial maps of SSS, based on the Aquarius remote-sensing, are constructed using the optimal interpolation technique. A novel approach utilizes the long-wavelength error correlation, specified for each Aquarius track (beam) and for a given cycle. This results in much reduced inter-beam biases (which, if not treated, produce characteristic stripes in the SSS maps) and ascending-descending differences. The analysis demonstrates a consistent pattern of seasonal variability which is most pronounced in the tropical band and off the north-east coast of South America, extending as far as 25N. Other kinds of variability, characterized by strong spatial gradients, include rapid temporal changes on time scales as short as one month in some cases. Over the SPURS domain, the seasonal cycle, measured by Aquarius, is relatively weak with the amplitude of about 0.4 psu, consistent with the climatological data. The mesoscale variability of SSS is investigated using high-resolution TSG data. Wavenumber power density spectra of SSS are computed to determine the spatial decorrelation scales as well as other statistical parameters required (e.g.) for optimal interpolation of the high-resolution SSS data from Aquarius, and to assess errors due to the components of variability not resolved by the Aquarius measurements. In the wavelength range from 15 km to 400 km, the spectral energy density of SSS follows a power law with the slope n=-1.9. This slope is much steeper than the theoretical arguments of geostrophic turbulence predict under the assumption that SSS is a passive tracer

  4. 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.

  5. Tropical and Subtropical Cloud Transitions in Weather and Climate Prediction Models: The GCSS/WGNE Pacific Cross-Section Intercomparison (GPCI)

    NASA Technical Reports Server (NTRS)

    Teixeira, J.; Cardoso, S.; Bonazzola, M.; Cole, J.; DeGenio, A.; DeMott, C.; Franklin, C.; Hannay, C.; Jakob, C.; Jiao, Y.; Karlsson, J.; Kitagawa, H.; Kohler, M.; Kuwano-Yoshida, A.; LeDrian, C.; Turk, F. J.

    2011-01-01

    A model evaluation approach is proposed in which weather and climate prediction models are analyzed along a Pacific Ocean cross section, from the stratocumulus regions off the coast of California, across the shallow convection dominated trade winds, to the deep convection regions of the ITCZ the Global Energy and Water Cycle Experiment Cloud System Study/Working Group on Numerical Experimentation (GCSS/ WGNE) Pacific Cross-Section Intercomparison (GPCI). The main goal of GPCI is to evaluate and help understand and improve the representation of tropical and subtropical cloud processes in weather and climate prediction models. In this paper, a detailed analysis of cloud regime transitions along the cross section from the subtropics to the tropics for the season June July August of 1998 is presented. This GPCI study confirms many of the typical weather and climate prediction model problems in the representation of clouds: underestimation of clouds in the stratocumulus regime by most models with the corresponding consequences in terms of shortwave radiation biases; overestimation of clouds by the 40-yr ECMWF Re-Analysis (ERA-40) in the deep tropics (in particular) with the corresponding impact in the outgoing longwave radiation; large spread between the different models in terms of cloud cover, liquid water path and shortwave radiation; significant differences between the models in terms of vertical cross sections of cloud properties (in particular), vertical velocity, and relative humidity. An alternative analysis of cloud cover mean statistics is proposed where sharp gradients in cloud cover along the GPCI transect are taken into account. This analysis shows that the negative cloud bias of some models and ERA-40 in the stratocumulus regions [as compared to the first International Satellite Cloud Climatology Project (ISCCP)] is associated not only with lower values of cloud cover in these regimes, but also with a stratocumulus-to-cumulus transition that occurs too

  6. Tropical and subtropical cloud transitions in weather and climate prediction models: the GCSS/WGNE Pacific Cross-Section Intercomparison (GPCI)

    SciTech Connect

    Teixeira, J.; Cardoso, S.; Bonazzola, M.; Cole, Jason N.; DelGenio, Anthony D.; DeMott, C.; Franklin, A.; Hannay, Cecile; Jakob, Christian; Jiao, Y.; Karlsson, J.; Kitagawa, H.; Koehler, M.; Kuwano-Yoshida, A.; LeDrian, C.; Lock, Adrian; Miller, M.; Marquet, P.; Martins, J.; Mechoso, C. R.; Meijgaard, E. V.; Meinke, I.; Miranda, P.; Mironov, D.; Neggers, Roel; Pan, H. L.; Randall, David A.; Rasch, Philip J.; Rockel, B.; Rossow, William B.; Ritter, B.; Siebesma, A. P.; Soares, P.; Turk, F. J.; Vaillancourt, P.; Von Engeln, A.; Zhao, M.

    2011-11-01

    A model evaluation approach is proposed where weather and climate prediction models are analyzed along a Pacific Ocean cross-section, from the stratocumulus regions off the coast of California, across the shallow convection dominated trade-winds, to the deep convection regions of the ITCZ: the GCSS/WGNE Pacific Cross-section Intercomparison (GPCI). The main goal of GPCI is to evaluate, and help understand and improve the representation of tropical and sub-tropical cloud processes in weather and climate prediction models. In this paper, a detailed analysis of cloud regime transitions along the cross-section from the sub-tropics to the tropics for the season JJA of 1998 is presented. This GPCI study confirms many of the typical weather and climate prediction model problems in the representation of clouds: underestimation of clouds in the stratocumulus regime by most models with the corresponding consequences in terms of shortwave radiation biases; overestimation of clouds by the ECMWF Re-Analysis (ERA40) in the deep tropics (in particular) with the corresponding impact in the outgoing longwave radiation; large spread between the different models in terms of cloud cover, liquid water path and shortwave radiation; significant differences between the models in terms of vertical crosssections of cloud properties (in particular), vertical velocity and relative humidity. An alternative analysis of cloud cover mean statistics is proposed where sharp gradients in cloud cover along the GPCI transect are taken into account. This analysis shows that the negative cloud bias of some models and ERA40 in the stratocumulus regions (as compared to ISCCP) is associated not only with lower values of cloud cover in these regimes, but also with a stratocumulus-to-cumulus transition that occurs too early along the trade-wind Lagrangian trajectory. Histograms of cloud cover along the cross-section differ significantly between models. Some models exhibit a quasi-bimodal structure with cloud

  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. North Pacific decadal variability in the CMIP5 last millennium simulations

    NASA Astrophysics Data System (ADS)

    Fleming, Laura E.; Anchukaitis, Kevin J.

    2016-02-01

    The Pacific ocean-atmosphere system exerts an important influence on the climate of Asia and North America, but the limited length of the observational record prevents a complete understanding of its bidecadal and multidecadal time scales. Paleoclimate reconstructions provide one source of information on longer time scales, although they differ in their estimation of the behavior of the Pacific decadal oscillation (PDO) prior to the instrumental period. Forced general circulation model simulations offer complementary long-term perspectives on both the history and dynamics of this important mode of variability. Here, we analyze the PDO in the ensemble of CMIP5/PMIP3 last millennium (past1000 + historical) simulations. We evaluate the modeled spatial, temporal, and spectral characteristics of this mode, as well as teleconnections between North Pacific variability and global climate. All models produce a mode of North Pacific variability over the last millennium with spatial patterns and spectral power density similar to observations. CCSM, FGOALS, and IPSL best reproduce observed spatial patterns, spectral characteristics, and teleconnections to terrestrial regions used in paleoclimate proxy reconstructions. In these simulations, the PDO shows no consistent response to solar or volcanic forcing.

  9. Multiproxy Comparison of Climatic and Oceanographic Conditions in the Subtropical North Atlantic During the Last 20,000 Years

    NASA Astrophysics Data System (ADS)

    Yanchilina, A. G.; McManus, J. F.; Eglinton, T. I.; Montlucon, D. B.

    2009-05-01

    . Together, they demonstrate that the climate was colder during the deglacial Heinrich iceberg discharge event (H1) than during the Last Glacial Maximum (LGM) by approximately 5°C at the Bermuda Rise and 7°C at the Iberian Margin. The 231Pa/230Th at Bermuda Rise illustrates that the ocean circulation was slower during H1 than the LGM. In fact, the 231Pa/230Th approached 0.093, its production ratio and suggests a dramatic reduction in ocean heat transport. The δ18O reconstruction is also characterized by an increase near H1 from approximately 1.75 to 2.5 ‰, equivalent to several degrees cooling. The comparison of these several proxies in two different regions of the subtropical North Atlantic provides strong evidence that the climate was more extreme during a time interval in the deglaciation than during LGM, most likely due to greatly diminished oceanic meridional overturning circulation.

  10. 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.

  11. 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.

  12. 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.

  13. Decadal variability in the oxygen inventory of North Atlantic subtropical underwater captured by sustained, long-term oceanographic time series observations

    NASA Astrophysics Data System (ADS)

    Montes, Enrique; Muller-Karger, Frank E.; Cianca, Andrés.; Lomas, Michael W.; Lorenzoni, Laura; Habtes, Sennai

    2016-03-01

    Historical observations of potential temperature (θ), salinity (S), and dissolved oxygen concentrations (O2) in the tropical and subtropical North Atlantic (0-500 m; 0-40°N, 10-90°W) were examined to understand decadal-scale changes in O2 in subtropical underwater (STUW). STUW is observed at four of the longest, sustained ocean biogeochemical and ecological time series stations, namely, the CArbon Retention In A Colored Ocean (CARIACO) Ocean Time Series Program (10.5°N, 64.7°W), the Bermuda Atlantic Time-series Study (BATS; 31.7°N, 64.2°W), Hydrostation "S" (32.1°N, 64.4°W), and the European Station for Time-series in the Ocean, Canary Islands (ESTOC; 29.2°N, 15.5°W). Observations over similar time periods at CARIACO (1996-2013), BATS (1988-2011), and Hydrostation S (1980-2013) show that STUW O2 has decreased approximately 0.71, 0.28, and 0.37 µmol kg-1 yr-1, respectively. No apparent change in STUW O2 was observed at ESTOC over the course of the time series (1994-2013). Ship observation data for the tropical and subtropical North Atlantic archived at NOAA National Oceanographic Data Center show that between 1980 and 2013, STUW O2 (upper ~300 m) declined 0.58 µmol kg-1 yr-1 in the southeastern Caribbean Sea (10-15°N, 60-70°W) and 0.68 µmol kg-1 yr-1 in the western subtropical North Atlantic (30-35°N, 60-65°W). A declining O2 trend was not observed in the eastern subtropical North Atlantic (25-30°N, 15-20°W) over the same period. Most of the observed O2 loss seems to result from shifts in ventilation associated with decreased wind-driven mixing and a slowing down of STUW formation rates, rather than changes in diffusive air-sea O2 gas exchange or changes in the biological oceanography of the North Atlantic. Variability of STUW O2 showed a significant relationship with the wintertime (January-March) Atlantic Multidecadal Oscillation index (AMO, R2 = 0.32). During negative wintertime AMO years trade winds are typically stronger between 10°N and 30

  14. 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.

  15. Linear relation of central and eastern North American precipitation to tropical Pacific Sea surface temperature anomalies

    SciTech Connect

    Montroy, D.L.

    1997-04-01

    In past research the Southern Oscillation index has often been used as an indicator of the tropical Pacific climate, notably for El Nino and La Nina event occurrences. This study identifies calendar monthly teleconnection signals in central and eastern North American precipitation associated with an alternative tropical Pacific indicator, sea surface temperature anomaly (SSTA) patterns. Using an approximate 1{degrees} resolution set of monthly precipitation totals for 1950-92, the work identifies monthly teleconnection relationships and their intraseasonal evolution. This builds upon previous studies that were limited to seasonal timescales. Here, a unique two-way statistical analysis is used to delineate linear SSTA-precipitation teleconnection patterns.

  16. Inversion of the western Pacific subtropical high dynamic model and analysis of dynamic characteristics for its abnormality

    NASA Astrophysics Data System (ADS)

    Hong, M.; Zhang, R.; Li, J. X.; Ge, J. J.; Liu, K. F.

    2013-02-01

    Based on time series data of 500 hPa potential field from NCEP/NCAR (National Center for Environmental Forecast of American/National Center for Atmospheric Research), a novel consideration of empirical orthogonal function (EOF) time-space separation and dynamic system reconstruction for time series is introduced. This method consists of two parts: first, the dynamical model inversion and model parameter optimization are carried out on the EOF time coefficient series using the genetic algorithm (GA), and, second, a nonlinear dynamic model representing the subtropical high (SH) activity and its abnormality is established. The SH activity and its abnormal mechanism is studied using the developed dynamical model. Results show that the configuration and diversification of the SH equilibriums have good correspondence with the actual short-medium term abnormal activity of the SH. Change of SH potential field brought by the combination of equilibriums is more complex than that by mutation, and their exhibition patterns are different. The mutation behavior from high-value to low-value equilibriums of the SH in summer corresponds with the southward drop of the SH in the observed weather process. The combination behavior of the two steady equilibriums corresponds with disappearance of the "double-ridge" phenomenon of the SH. Dynamical mechanisms of these phenomena are explained.

  17. Distribution of copper, nickel, and cadmium in the surface waters of the North Atlantic and North Pacific Ocean

    SciTech Connect

    Boyle, E.A.; Huested, S.S.; Jones, S.P.

    1981-09-20

    Concentrations of copper, nickel, and cadmium have been determined for about 250 surface water samples. Nonupwelling open-ocean concentrations of these metals are Cu, 0.5-1.4 nmol/kg: Ni, 1-2 nmol/kg; and Cd, less than 10 pmol/kg. In the equatorial Pacific upwelling zone, concentrations of Ni (3 nmol/kg) and Cd (80 pmol/kg) are higher than in the open ocean, but Cu (0.9 nmol/kg) is not significantly enriched. Metal concentrations are higher in cool, nutrient-rich eastern boundary currents: Cu, 1.5 nmol/kg: Ni, 3.5 nmol/kg and Cd, 30-50 pmol/kg. Copper is distinctly higher in the coastal waters of the Gulf of Panama (3--4 nmol/kg) and also higher in the shelf waters north of the Gulf Stream (2.5 nmol/kg): these copper enrichments may be caused by copper remobilized from mildly reducing shelf sediments and maintained by a coastal nutrient trap. In the open ocean, events of high-Cu water (1.5--3.5 nmol/kg) are seen on scales up to 60 km; presumably, these are due to the advection of coastal water into the ocean interior. The lowest copper concentrations in the North Pacific central gyre (0.5 nmol/kg: (Bruland, 1980) are lower than in the Sargasso Sea (1.3 nmol/kg), while for nickel the lowest concentrations are 2 nmol/kg in both the North Pacific and the North Atlantic. Nickel and cadmium, while generally correlated with the nutrients in surface waters, show distinct regional changes in their element-nutrient correlations. The residual concentrations of trace metals in the surface waters of the ocean can be explained if biological discrimination against trace metals relative to phosphorus increases as productivity decreases.

  18. Bifurcations and catastrophes in a nonlinear dynamical model of the western Pacific subtropical high ridge line index and its evolution mechanism

    NASA Astrophysics Data System (ADS)

    Hong, Mei; Zhang, Ren; Li, Ming; Wang, Shuo; Zeng, Wenhua; Wang, Zhengxin

    2016-04-01

    Despite much previous effort, the establishment of an accurate model of the western Pacific subtropical high (WPSH) and analysis of its chaotic behavior has proved to be difficult. Based on a phase-space technique, a nonlinear dynamical model of the WPSH ridge line and summer monsoon factors is constructed here from 50 years of data. Using a genetic algorithm, model inversion and parameter optimization are performed. The Lyapunov spectrum, phase portraits, time history, and Poincaré surface of section of the model are analyzed and an initial-value sensitivity test is performed, showing that the model and data have similar phase portraits and that the model is robust. Based on equilibrium stability criteria, four types of equilibria of the model are analyzed. Bifurcations and catastrophes of the equilibria are studied and related to the physical mechanism and actual weather phenomena. The results show that the onset and enhancement of the Somali low-level jet and the latent heat flux of the Indian monsoon are among the most important reasons for the appearance and maintenance of the double-ridge phenomenon. Violent breakout and enhancement of the Mascarene cold high will cause the WPSH to jump northward, resulting in the "empty plum" phenomenon. In the context of bifurcation and catastrophe in the dynamical system, the influence of the factors considered here on the WPSH has theoretical and practical significance. This work also opens the way to new lines of research on the interaction between the WPSH and the summer monsoon system.

  19. Variations of surface O3 in August at a rural site near Shanghai: influences from the West Pacific subtropical high and anthropogenic emissions.

    PubMed

    He, Jingwei; Wang, Yuxuan; Hao, Jiming; Shen, Lulu; Wang, Long

    2012-11-01

    Large day-to-day variability in O(3) and CO was observed at Chongming, a remote rural site east of Shanghai, in August 2010. High ozone periods (HOPs) that typically lasted for 3-5 days with daily maximum ozone exceeding 102 ppb were intermittent with low ozone periods (LOPs) with daily maximum ozone less than 20 ppb. The correlation analysis of ozone with meteorological factors suggests that the large variations of surface ozone are driven by meteorological conditions correlated with the changes in the location and intensity of the west Pacific subtropical high (WPSH) associated with the East Asian summer monsoon (EASM). When the center of WPSH with weaker intensity is to the southeast of Chongming site, the mixing ratios and variability of surface ozone are higher. When the center of WPSH with stronger intensity is to the northeast of Chongming site, the mixing ratios and variability of surface ozone are lower. Sensitivity simulations using the GEOS-Chem chemical transport model indicate that meteorological condition associated with WPSH is the primary factor controlling surface ozone at Chongming in August, while local anthropogenic emissions make significant contributions to surface ozone concentrations only during HOP. PMID:22648346

  20. Climatology of new particle formation at Izaña mountain GAW observatory in the subtropical North Atlantic

    NASA Astrophysics Data System (ADS)

    García, M. I.; Rodríguez, S.; González, Y.; García, R. D.

    2014-04-01

    A climatology of new particle formation (NPF) events at high altitude in the subtropical North Atlantic is presented. A 4-year data set (June 2008-June 2012), which includes number size distributions (10-600 nm), reactive gases (SO2, NOx, and O3), several components of solar radiation and meteorological parameters, measured at Izaña Global Atmosphere Watch (GAW) observatory (2373 m above sea level; Tenerife, Canary Islands) was analysed. NPF is associated with the transport of gaseous precursors from the boundary layer by orographic buoyant upward flows that perturb the low free troposphere during daytime. On average, 30% of the days contained an NPF event. Mean values of the formation and growth rates during the study period were 0.46 cm-3 s-1 and 0.42 nm h-1, correspondingly. There is a clearly marked NPF season (May-August), when these events account for 50-60% of the days per month. Monthly mean values of the formation and growth rates exhibit higher values in this season, 0.49-0.92 cm-3 s-1 and 0.48-0.58 nm h-1, respectively. During NPF events, SO2, UV radiation and upslope winds showed higher values than during non-events. The overall data set indicates that SO2 plays a key role as precursor, although other species seem to contribute during some periods. Condensation of sulfuric acid vapour accounts for most of the measured particle growth during most of the year (~70%), except for some periods. In May, the highest mean growth rates (~0.6 nm h-1) and the lowest contribution of sulfuric acid (~13%) were measured, suggesting a significant involvement of other condensing vapours. The SO2 availability seems also to be the most influencing parameter in the year-to-year variability in the frequency of NPF events. The condensation sink showed similar features to other mountain sites, showing high values during NPF events. Summertime observations, when Izaña is within the Saharan Air Layer, suggest that dust particles may play a significant role acting as

  1. Distant Influence of Kuroshio Eddies on North Pacific Weather Patterns?

    PubMed

    Ma, Xiaohui; Chang, Ping; Saravanan, R; Montuoro, Raffaele; Hsieh, Jen-Shan; Wu, Dexing; Lin, Xiaopei; Wu, Lixin; Jing, Zhao

    2015-01-01

    High-resolution satellite measurements of surface winds and sea-surface temperature (SST) reveal strong coupling between meso-scale ocean eddies and near-surface atmospheric flow over eddy-rich oceanic regions, such as the Kuroshio and Gulf Stream, highlighting the importance of meso-scale oceanic features in forcing the atmospheric planetary boundary layer (PBL). Here, we present high-resolution regional climate modeling results, supported by observational analyses, demonstrating that meso-scale SST variability, largely confined in the Kuroshio-Oyashio confluence region (KOCR), can further exert a significant distant influence on winter rainfall variability along the U.S. Northern Pacific coast. The presence of meso-scale SST anomalies enhances the diabatic conversion of latent heat energy to transient eddy energy, intensifying winter cyclogenesis via moist baroclinic instability, which in turn leads to an equivalent barotropic downstream anticyclone anomaly with reduced rainfall. The finding points to the potential of improving forecasts of extratropical winter cyclones and storm systems and projections of their response to future climate change, which are known to have major social and economic impacts, by improving the representation of ocean eddy-atmosphere interaction in forecast and climate models. PMID:26635077

  2. Distant Influence of Kuroshio Eddies on North Pacific Weather Patterns?

    NASA Astrophysics Data System (ADS)

    Ma, Xiaohui; Chang, Ping; Saravanan, R.; Montuoro, Raffaele; Hsieh, Jen-Shan; Wu, Dexing; Lin, Xiaopei; Wu, Lixin; Jing, Zhao

    2015-12-01

    High-resolution satellite measurements of surface winds and sea-surface temperature (SST) reveal strong coupling between meso-scale ocean eddies and near-surface atmospheric flow over eddy-rich oceanic regions, such as the Kuroshio and Gulf Stream, highlighting the importance of meso-scale oceanic features in forcing the atmospheric planetary boundary layer (PBL). Here, we present high-resolution regional climate modeling results, supported by observational analyses, demonstrating that meso-scale SST variability, largely confined in the Kuroshio-Oyashio confluence region (KOCR), can further exert a significant distant influence on winter rainfall variability along the U.S. Northern Pacific coast. The presence of meso-scale SST anomalies enhances the diabatic conversion of latent heat energy to transient eddy energy, intensifying winter cyclogenesis via moist baroclinic instability, which in turn leads to an equivalent barotropic downstream anticyclone anomaly with reduced rainfall. The finding points to the potential of improving forecasts of extratropical winter cyclones and storm systems and projections of their response to future climate change, which are known to have major social and economic impacts, by improving the representation of ocean eddy-atmosphere interaction in forecast and climate models.

  3. Distant Influence of Kuroshio Eddies on North Pacific Weather Patterns?

    PubMed Central

    Ma, Xiaohui; Chang, Ping; Saravanan, R.; Montuoro, Raffaele; Hsieh, Jen-Shan; Wu, Dexing; Lin, Xiaopei; Wu, Lixin; Jing, Zhao

    2015-01-01

    High-resolution satellite measurements of surface winds and sea-surface temperature (SST) reveal strong coupling between meso-scale ocean eddies and near-surface atmospheric flow over eddy-rich oceanic regions, such as the Kuroshio and Gulf Stream, highlighting the importance of meso-scale oceanic features in forcing the atmospheric planetary boundary layer (PBL). Here, we present high-resolution regional climate modeling results, supported by observational analyses, demonstrating that meso-scale SST variability, largely confined in the Kuroshio-Oyashio confluence region (KOCR), can further exert a significant distant influence on winter rainfall variability along the U.S. Northern Pacific coast. The presence of meso-scale SST anomalies enhances the diabatic conversion of latent heat energy to transient eddy energy, intensifying winter cyclogenesis via moist baroclinic instability, which in turn leads to an equivalent barotropic downstream anticyclone anomaly with reduced rainfall. The finding points to the potential of improving forecasts of extratropical winter cyclones and storm systems and projections of their response to future climate change, which are known to have major social and economic impacts, by improving the representation of ocean eddy–atmosphere interaction in forecast and climate models. PMID:26635077

  4. Tropically mediated global responses to cataclysmic flooding in the eastern North Pacific by Glacial Lake Missoula (and variations in response based on initial onset)

    NASA Astrophysics Data System (ADS)

    Gambs, M. F.; Thompson, L.; Hautala, S. L.; Bitz, C. M.

    2012-12-01

    The Missoula Floods (18.6 to 14.5 ka) were a series of jökulhlaups (freshwater glacial-outburst floods) from proglacial Lake Missoula, during the Last Glacial Maximum (LGM). These episodic floods carved the Quaternary landscape of Eastern Washington and northern Oregon, flowing rapidly into the Pacific Ocean via the Columbia River. This study investigates the short-term global ocean and climate response to the freshwater discharge from the Missoula Floods into the eastern North Pacific Ocean. We simulate the floods by adding freshwater north of 42°N and east of 140°W, from the surface, tapering to 920 m and restarting a run of the Community Climate System Model, version 3 (CCSM3) configured for Last Glacial Maximum conditions. The method is similar to that used in freshwater hosing experiments in the North Atlantic. Fourteen runs were completed, seven initialize during El Niño conditions, and seven during La Niña conditions as defined by the Niño 3.4 index (5°S to 5°N and 170°W to 120°W). Ensemble means are made and compared against control ensembles without the freshwater input. We find a global response within one year of freshwater input, with warming to the west of the hosing region and cooling to the south. The response is larger for La Niña conditions, with warming in the tropical Pacific of more than 0.5°C and an even larger warming throughout Antarctica with warming of more than 1.5°C, in the first year following freshening. The Southern Ocean also warms, particularly in the Atlantic sector. During El Niño conditions, Greenland warms by more than 1°C and there is warming confined to the Pacific Sector over Greenland and the Southern Ocean. The changes in surface temperatures are accompanied by changes in sea-ice extent in both hemispheres. Changes in the Tropical Pacific are initiated by sea surface temperature gradients associated with the freshwater input that then modify the winds in the subtropics.

  5. Status Assessment of Laysan and Black-Footed Albatrosses, North Pacific Ocean, 1923-2005

    USGS Publications Warehouse

    Arata, Javier A.; Sievert, Paul R.; Naughton, Maura B.

    2009-01-01

    Over the past century, Laysan (Phoebastria immutabilis) and black-footed (Phoebastria nigripes) albatrosses have been subjected to high rates of mortality and disturbance at the breeding colonies and at sea. Populations were greatly reduced and many colonies were extirpated around the turn of the 20th century as a result of feather hunting. Populations were recovering when military occupation of several breeding islands during World War II led to new population declines at these islands and additional colony extirpations. At sea, thousands of Laysan and black-footed albatrosses were killed each year in high-seas driftnet fisheries, especially from 1978 until the fisheries were banned in 1992. Through the 1990s, there was a growing awareness of the large numbers of albatrosses that were being killed in longline fisheries. During the 1990s, other anthropogenic factors, such as predation by non-native mammals and exposure to contaminants, also were documented to reduce productivity or increase mortality. In response to the growing concerns over the impacts of these threats on albatross populations, the U.S. Fish and Wildlife Service contracted with the U.S. Geological Survey to conduct an assessment of Laysan and black-footed albatross populations. This assessment includes a review of the taxonomy, legal status, geographic distribution, natural history, habitat requirements, threats, and monitoring and management activities for these two species. The second part of the assessment is an analysis of population status and trends from 1923 to 2005. Laysan and black-footed albatrosses forage throughout the North Pacific Ocean and nest on tropical and sub-tropical oceanic islands from Mexico to Japan. As of 2005, 21 islands support breeding colonies of one or both species. The core breeding range is the Hawaiian Islands, where greater than 99 percent of the World's Laysan albatrosses and greater than 95 percent of the black-footed albatrosses nest on the small islands and

  6. Oceanography. Centennial changes in North Pacific anoxia linked to tropical trade winds.

    PubMed

    Deutsch, Curtis; Berelson, William; Thunell, Robert; Weber, Thomas; Tems, Caitlin; McManus, James; Crusius, John; Ito, Taka; Baumgartner, Timothy; Ferreira, Vicente; Mey, Jacob; van Geen, Alexander

    2014-08-01

    Climate warming is expected to reduce oxygen (O2) supply to the ocean and expand its oxygen minimum zones (OMZs). We reconstructed variations in the extent of North Pacific anoxia since 1850 using a geochemical proxy for denitrification (δ(15)N) from multiple sediment cores. Increasing δ(15)N since ~1990 records an expansion of anoxia, consistent with observed O2 trends. However, this was preceded by a longer declining δ(15)N trend that implies that the anoxic zone was shrinking for most of the 20th century. Both periods can be explained by changes in winds over the tropical Pacific that drive upwelling, biological productivity, and O2 demand within the OMZ. If equatorial Pacific winds resume their predicted weakening trend, the ocean's largest anoxic zone will contract despite a global O2 decline. PMID:25104384

  7. Centennial changes in North Pacific anoxia linked to tropical trade winds

    USGS Publications Warehouse

    Deutsch, Curtis; Berelson, William; Thunell, Robert; Weber, Thomas; Tems, Caitlin; McManus, James; Crusius, John; Ito, Taka; Baumgartner, Timothy; Ferreira, Vicente; Mey, Jacob; van Geen, Alexander

    2014-01-01

    Climate warming is expected to reduce oxygen (O2) supply to the ocean and expand its oxygen minimum zones (OMZs). We reconstructed variations in the extent of North Pacific anoxia since 1850 using a geochemical proxy for denitrification (δ15N) from multiple sediment cores. Increasing δ15N since ~1990 records an expansion of anoxia, consistent with observed O2 trends. However, this was preceded by a longer declining δ15N trend that implies that the anoxic zone was shrinking for most of the 20th century. Both periods can be explained by changes in winds over the tropical Pacific that drive upwelling, biological productivity, and O2 demand within the OMZ. If equatorial Pacific winds resume their predicted weakening trend, the ocean’s largest anoxic zone will contract despite a global O2 decline.

  8. Understanding Abrupt, Natural Climate Variability Post-Industrial Revolution from the Subtropical Eastern Pacific: A Novel High Resolution Alkenone-derived Sea Surface Temperature Record

    NASA Astrophysics Data System (ADS)

    Kelly, C. S.; O'Mara, N. A.; Herbert, T.; Abella-Gutiérrez, J. L.; Herguera, J. C.

    2015-12-01

    Despite the ocean's importance in global biogeochemical feedbacks and heat storage, there is still a paucity of decadally-resolved sea surface temperature (SST) records to complement lacustrine and dendrological records of recent paleoclimate. Natural climate variability on multidecadal timescales is dominated by internal ocean circulation dynamics and feedbacks, and it is therefore imperative to employ marine proxies to reconstruct high resolution climate change. The timescales of this ocean-induced natural climate variability can be broken down into a few characteristic climate modes. Pressing questions about these modes include their stationarity in frequency and amplitude over time, in addition to the hypothesis that anthropogenic climate change has altered their behavior in comparison to natural variability. To pursue these questions, we must discern and analyze suitable climate archives in regions where modes of interest dominate modern climate variability. The region of Baja California, Mexico exhibits exceptional teleconnection to the El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). Local, dramatic effects of ENSO and PDO on the marine biology and economy underline the importance of regional paleoclimate records from the Baja peninsula. Here, we present a high-resolution alkenone-derived SST reconstruction from the Industrial Revolution through the year 2000 by analysis of laminated box and Kasten sediment cores at Site PCM 00-78 (25.18°N, 112.66°W) in the subtropical eastern Pacific at a depth of 540 meters. Our SST record corresponds with NOAA extended reconstructed sea surface temperature, providing a robust basis for organic geochemical marine climatic reconstructions on timescales usually accessible only through speleothems, coral density bands, tree rings, and the like. Accordingly, based on this comparison to the historical data we expect our SST record may provide a more robust record of inter and multidecadal

  9. Anisotropy from SKS splitting across the Pacific-North America plate boundary offshore southern California

    NASA Astrophysics Data System (ADS)

    Ramsay, Joseph; Kohler, Monica D.; Davis, Paul M.; Wang, Xinguo; Holt, William; Weeraratne, Dayanthie S.

    2016-07-01

    SKS arrivals from ocean bottom seismometer (OBS) data from an offshore southern California deployment are analyzed for shear-wave splitting. The project involved 34 OBSs deployed for 12 months in a region extending up to 500 kilometers west of the coastline into the oceanic Pacific plate. The measurement process consisted of removing the effects of anisotropy using a range of values for splitting fast directions and delay times to minimize energy along the transverse seismometer axis. Computed splitting parameters are unexpectedly similar to onland parameters, exhibiting WSW-ENE fast polarization directions and delays between 0.8 and 1.8 s, even for oceanic plate sites. This is the first SKS splitting study to extend across the entire boundary between the North America and Pacific plates, into the oceanic part of the Pacific plate. The splitting results show that the fast direction of anisotropy on the Pacific plate does not align with absolute plate motion (APM), and they extend the trend of anisotropy in southern California an additional 500 km west, well onto the oceanic Pacific plate. We model the finite strain and anisotropy within the asthenosphere associated with density-buoyancy driven mantle flow and the effects of APM. In the absence of plate motion effects, such buoyancy driven mantle flow would be NE-directed beneath the Pacific plate observations. The best-fit patterns of mantle flow are inferred from the tomography-based models that show primary influences from foundering higher-density zones associated with the history of subduction beneath North America. The new offshore SKS measurements, when combined with measurements onshore within the plate boundary zone, indicate that dramatic lateral variations in density-driven upper mantle flow are required from offshore California into the plate boundary zone in California and western Basin and Range.

  10. Iron deficiency limits phytoplankton growth in the north-east Pacific subarctic

    NASA Astrophysics Data System (ADS)

    Martin, John H.; Fitzwater, Steve E.

    1988-01-01

    An interesting oceanographic problem concerns the excess major plant nutrients (PO4, NO3, SiO3) occurring in offshore surface waters of the Antarctic1-3 and north-east Pacific subarctic Oceans4. In a previous study5, we presented indirect evidence suggesting that inadequate Fe input was responsible for this limitation of growth; recently we had the opportunity to seek direct evidence for this hypothesis in the north-east Pacific subarctic. We report here that the addition of nmol amounts of dissolved iron resulted in the nearly complete utilization of excess NO3, whereas in the controls-without added Fe-only 25% of the available NO3 was used. We also observed that the amounts of chlorophyll in the phytoplankton increased in proportion to the Fe added. We conclude that Fe deficiency is limiting phytoplankton growth in these major-nutrient-rich waters.