Stations North Research Articles

Stoichiometry of carbon, hydrogen, nitrogen, sulfur and oxygen in the particulate matter of the western North Pacific marginal seas

Abstract The suspended particulate matter (SPM) in surface seawater was collected from 19 stations in the Sea of Japan, 42 stations in the East China Sea, 7 stations North of Taiwan and 6 stations in the Philippine Sea and the Bashi Channel. The particulate organic carbon (POC), particulate organic hydrogen (POH), particulate organic nitrogen (PON), particulate organic sulfur (POS), particulate organic oxygen (POO), particulate phosphorus (PP) and total organic matter (TOM) concentrations were determined. In the Sea of Japan these concentrations were generally lower in the region affected by the Kuroshio branch. In the East China Sea high concentrations of SPM and other organic components were found at stations nearest the Yangtze River mouth, reflecting the terrestrial input. On the other hand, the values were lower in regions influenced by the Kuroshio. In the Philippine Sea and the Bashi Channel, the effect of terrestrial input was not obvious, resulting in lower concentrations of organic matter. The average molar ratios for all samples were C:H:N:S:O = 7.69(± 0.33): 8.73(± 1.62): 1.0: 0.16(± 0.014): 4.12(± 0.64).

Arctic sediments (Svalbard): pore water and solid phase distributions of C, N, P and Si

Pore water and solid phase distributions of C, N, P and Si in sediments of the Arctic Ocean (Svalbard area) have been investigated. Concentrations of organic carbon (Corg) in the solid phase of the sediment varied from 1.3 to 2.8% (mean 1.9%), with highest concentrations found at shallow stations south/southwest of Svalbard. Relatively low concentrations were obtained at the deeper stations north/northeast of Svalbard. Atomic carbon to nitrogen ratios in the surface sediment ranged from below 8 to above 10. For some stations, high C/N ratios together with high concentrations of Corg suggest that sedimentary organic matter is mainly of terrigenous origin and not from overall biological activity in the water column. Organic matter reactivity (defined as the total sediment oxygen consumption rate normalized to the organic carbon content of the surface sediment) correlated with water depth at all investigated stations. However, the stations could be divided into two separate groups with different reactivity characteristics, representing the two most dominant hydrographic regimes: the region west of Svalbard mainly influenced by the West Spitsbergen Current, and the area east of Svalbard where Arctic polar water set the environmental conditions. Decreasing sediment reactivity with water depth was confirmed by the partitioning between organic and inorganic carbon of the surface sediment. The ratio between organic and inorganic carbon at the sediment-water interface decreased exponentially with water depth: from indefinite values at shallow stations in the central Barents Sea, to approximately 1 at deep stations north of Svalbard. At stations east of Svalbard there was an inverse linear correlation between the organic matter reactivity (as defined above) and concentration of dissolved organic carbon (DOC) in the pore water. The more reactive the sediment, the less DOC existed in the pore water and the more total carbonate (Ct or ΣCO2) was present. This observation suggests that DOC produced in reactive sediments is easily metabolizable to CO2. Sediment accumulation rates of opaline silica ranged from 0.35 to 5.7 µmol SiO2 m−2d−1 (mean 1.3 µmol SiO2 m−2d−1), i.e. almost 300 times lower than rates previously reported for the Ross Sea, Antarctica. Concentrations of ammonium and nitrate in the pore water at the sediment-water interface were related to organic matter input and water depth. In shallow regions with highly reactive organic matter, a pool of ammonium was present in the pore water, while nitrate conoentrations were low. In areas where less reactive organic matter was deposited at the sediment surface, the deeper zone of nitrification caused a build-up of nitrate in the pore water while ammonium was almost depleted. Nitrate penetrated from 1.8 to ≥ 5.8 cm into the investigated sediments. Significantly higher concentrations of “total” dissolved nitrogen (defined as the sum of NO3, NO2, NH4 and urea) in sediment pore water were found west compared to east of Svalbard. The differences in organic matter reactivity, as well as in pore water distribution patterns of “total” dissolved nitrogen between the two areas, probably reflect hydrographic factors (such as ice coverage and production/import of particulate organic material) related to the dominant water mass (Atlantic or Arctic Polar) in each of the two areas.

Total amount of oceanic excess CO2 taken from the North Pacific subpolar region

Concentrations of total carbonate, alkalinity and dissolved oxygen were obtained near the 1973 GEOSECS stations in the North Pacific subpolar region north of 40°N along 175°E between 1993 and 1994. A difference of excess CO2 content between the GEOSECS and our expeditions was estimated. The maximum difference in water column inventory of excess CO2 has increased by about 280 gC m−2 above 2000 m depth which apparently means an uptake of excess CO2 taken from air to sea during the last two decades. An averaged value of the annual flux of excess CO2 at 75–1000 m depth was 8.63±2.01 gC m−2yr−1 in the North Pacific subpolar region. By introducing the annual flux of excess CO2 into a two-box model for the North Pacific subpolar region, a penetration factor of excess CO2 from air to sea was obtained to be 1.08×10−2 gC m−3ppm−1 in the North Pacific subpolar region. Based on this factor, the surface concentration of excess CO2 in the North Pacific subpolar region was estimated to be 68 μmole I−1, suggesting that the North Pacific subpolar region absorbed atmospheric excess CO2 more than the saturated concentration of excess CO2. Total amount of excess CO2 taken from the North Pacific subpolar region by 1993 was estimated to be 36.2×1015 gC, which was equal to about one tenth of that released by human activities after the preindustrial era.

Co-seismic Displacements of the 1995 Hyogo-ken Nanbu Earthquake.

We present co-seismic displacements of the Hyogo-ken Nanbu earthquake of January 17, 1995, detected by continuous GPS (Global Positioning System) observation, campaign type GPS survey and leveling. Continuous GPS observation gives a consistent pattern of displacements with those expected from a right lateral slip on a NE-SW trending vertical fault in far field: stations about 50 km east and west of the epicenter moved toward the epicenter by about 4 cm, while stations north and south moved away from the epicenter. By comparing with line lengths obtained by geodolite about 10 years ago, the campaign type GPS revealed most control points on Awaji Island moved to the southwest or south, which may be attributed to the movement of the Nojima Fault which cut the surface. On the other hand, control points northwest of the Rokko fault system moved toward the northeast and those on the other side moved slightly to the west, in and around Kobe. Leveling data revealed uplift of 19 cm on the northwestern side of the Suma Fault, a member of the Rokko fault system, and subsidence of 7 cm just east of this fault. Furthermore, uplift of about 5 cm was observed in the central part of Kobe City, and subsidence of 5 cm was detected east of Kobe. There is no significant gap in horizontal and vertical displacements around the northern extension of the Nojima Fault, which implies a complicated rupture process of this event. Leveling on the east coast of Awaji Island revealed a significant uplift of about 20 cm with slight subsidence at both edges of this uplift region during the past 20 years. By fitting the above geodetic data, we searched for an optimal set of parameters of a dislocation model. We assumed six nearly vertical faults trending NE-SW from Kobe to Awaji Island on the basis of aftershock distribution and focal mechanism. About 250 cm of the right lateral slip for the fault on Awaji Island is derived from large horizontal displacements near the Nojima Fault. The fault in Kobe may be divided into two segments with 100-200 cm slip by a slip-free zone which roughly corresponds to the cluster of aftershocks. The southern part of the Nojima Fault, segments near the Akashi Strait, and north of central Kobe may have significantly large thrust components of 100 cm. We also examined the possibility of buried faults beneath the zones of severe damage. Since this model cannot explain the observed geodetic data and the estimated slips are inconsistent with focal mechanism, these possible buried faults may not play a significant role, if any.

A Utility Perspective on Subchannel Analysis

Utility nuclear engineering organizations are among the primary end users of subchannel analysis technology. Typically there is only a limited involvement by utility staff in the actual development of subchannel software other than the addition of user convenience features such as editing routines and automated execution of multiple cases. There is, however, a large and increasing number of applications of subchannel codes, which indicates the continuing need for software improvements to meet the needs of the end user. The subchannel code has been and will continue to be an integral part of the analysis technology maintained by utilities to ensure safe and economical design and operation of reactors. An overview of the status of the application of subchannel analysis codes at one particular utility is presented. The utility is Duke Power which operates the Oconee, McGuire, and Catawba Nuclear Stations in North and South Carolina.

Probability studies of rainfall and crop production in coastal Tamil Nadu

Studies are made of the probability of Occurrence of annual and seasonal rainfall, wet and dry spells on monthly basis throughout the year and on weekly basis during the northeast monsoon season for various stations in coastal Tamil Nadu. It has been observed that amount of rainfall received is more in the stations north of Alangudi and north of Tondi in the northeast and southwest monsoon seasons respectively at all the probability levels. However, the quantum of rainfall is more in stations south of Adiramapattinam during the hot weather period. Number of wet spells are more from July to September in the stations of north costal Tamil Nadu. During the northeast monsoon season also wet weeks are mainly confined to the stations of north coastal Tamil Nadu. Analysis of production figures of some rainfed crops shows more productivity (k8I1\a) in north than in south coastal Tamil Nadu.

Atmospheric Water Vapor Characteristics at 70°N

Using an extensive rawinsonde archive, characteristics of Arctic water vapor and its transports at 70°N are examined for the period 1974–1991. Monthly-mean profiles and vertically integrated values of specific humidity and meridional vapor fluxes are computed for land stations north of 65°N for the surface up to 300 mb using once to twice daily soundings. Mean values at 70°N for these and other variables, including temperature and meridional winds, are obtained through an objective analysis of the monthly station means. The annual zonal mean specific humidity at 70°N ranges from 2.4 g kg−1 at the surface to 0.02 g kg−1 at 300 mb. Zonal-mean precipitable water ranges from 2.9 mm in February and March to 16.2 mm in July. For all months, over 95% of water vapor is found below 500 mb. Although mean winds are equatorward up to about 400 mb, the tendency for poleward winds to transport more water vapor results in a poleward annual-mean flux at all levels except at the surface, peaking at 1.5 g kg−1 m s−1 at 850 mb. Whereas over 85% of the integrated zonal-mean meridional flux is found below 500 mb for all months, a smaller percentage is found at lower levels during summer due to stronger equatorward winds. The flux convergence across 70°N is positive in all months, peaking in September at an equivalent monthly water depth of 22.1 mm averaged over the region north of 70°N. Aerological estimates of precipitation minus evaporation (P - E) for the area north of 70°N that account for changes in water storage also peak in September (26.1 mm), with the annual total of 163 mm larger than previous estimates by up to 36%. Integrated vapor transports exhibit marked longitudinal variations, with maximum annual poleward transports of 16–25 kg s−1 m−1 found over the Norwegian Sea and Baffin Bay. The Canadian Arctic archipelago is the only sector where mean integrated transports are equatorward, ranging from 1 to 10 kg s−1 m−1 depending on longitude. The September peak in P - E results from a circulation shift yielding poleward fluxes along a broad zone from near the prime meridian to 15O°E.

Seismic guided waves trapped in the fault zone of the Landers, California, earthquake of 1992

A mobile seismic array of seven stations was deployed at 11 sites along the fault trace of the M7.4 Landers earthquake of June 28, 1992, with a maximum offset of 1 km from the trace. We found a distinct wave train with a relatively long period following the S waves that shows up only when both the stations and the events are close to the fault trace. This wave train is interpreted as a seismic guided wave trapped in a low‐velocity fault zone. To study the distribution of amplitude of the guided waves with distance from the fault trace and also their attenuation with travel distance along the fault zone, we eliminated source and recording site effects by the coda normalization method. The normalized amplitudes of guided waves show a spectral peak at 3–4 Hz, which decays sharply with distance from the fault trace. Spectral amplitudes at high frequencies (8–15 Hz) show an opposite trend, increasing with distance from the fault trace. The normalized amplitudes of guided waves at 3–4 Hz also show a systematic decrease with hypocentral distance along the fault zone, from which we infer an apparent Q of 50. In order to confirm the existence of the guided waves, a dense array of 31 stations was deployed at one of the 11 sites. The resultant records revealed unequivocal evidence for the existence of guided waves associated with the fault zone. By modeling the waveforms as S waves trapped in a low‐velocity waveguide sandwiched between two homogeneous half‐spaces with velocity Vs = 3.0 km/s, we infer a waveguide width of about 180 m, a shear velocity of 2.0–2.2 km/s, and a Q of ∼50. Hypocenters of aftershocks with clear guided waves show a systematic distribution both laterally and with depth delineating the extent of the low‐velocity fault zone in three dimensions. We find that the zone extends to a depth of at least 10 km. This zone apparently continues to the south across the Pinto Mountain fault because guided waves are observed at stations north of the Pinto Mountain fault for earthquakes with epicenters south of it. On the other hand, the zone appears to be discontinuous at the fault bend located about 20 km north of the mainshock epicenter; guided waves were observed for stations and epicenters which are located on the same sides of the fault bend but not for those on the opposite sides.

On the spatio-temporal variations of the tropopause height over india and indian summer monsoon activity

The spatio-temporal variation of the tropopause height (TH) over the Indian region (5°N-35°N, 70°E-95°E) has been studied using monthly mean TH data, for 22-year period, 1965 to 1986. The study revealed that the stations south of 20°N showed maximum TH in April/May and minimum in September. This variation in TH has been attributed to the corresponding variation of average sea surface temperature (SST) over ±20° latitudinal belt over Indian Ocean, Arabian Sea and Bay of Bengal. Further the stations north of 20°N showed maximum in June and minimum in October/November. This maximum in TH has primarily been attributed to the increased insolation and convection. Furthermore it is noticed that the anomaly of TH moved northwards during the period April to July.

Effect of the abundance of three predominating copepod species on adequate sample volume and sample size in Bransfield Strait (Antarctic Peninsula) and waters north of the Weddell Sea

The effect on adequate sample size and sample volume of the abundances of three predominant copepod species, Metridia gerlachei, Calanus propinquus and Calanoides acutus, were studied in Bransfield Strait (Antarctic Peninsula) in the austral summer of 1988–1989 and waters north of the Weddell Sea in 1989–1990. Copepod abundances were higher in the area north of the Weddell Sea, with the exception of Metridia gerlachei, which was evenly distributed over both areas. Local (intra-station) patchiness was not found, indicating random distribution over small areas. In the assessment of inter-station variability in Bransfield Strait, with standard error of the mean set arbitrarily at 20% of the average abundance and a sampling volume of 150 m3, the theoretical minimum sample size (number of sampling stations) ranged from 6 to 17 for juvenile copepods and from 11 to 25 for adults. The minimum number of stations in the area north of the Weddell Sea reached from 5 to 7, and from 7 to 10 respectively.

Compliance Testing for Ocean Outfall Performance Utilising Natural Fluorescence of Effluent in Seawater Mixtures

Water samples were collected from public beaches at Sydney, Australia. The beaches were situated at various distances from the three major shoreline ocean outfalls discharging primary effluent. The samples were tested for faecal conform and faecal streptococci indicator bacteria. The same samples were also analysed for natural fluorescence. Excitation wavelength used was 280 nm and fluorescence emission from seawater effluent mixtures was observed at 445 nm. Indicator bacteria densities correlated well with fluorescence intensities for beach monitoring stations north of Sydney Harbour. Best correlations were observed for the stations situated within 5 kilometres from the outfall. Indicator bacteria densities were not as well correlated with fluorescence intensities for the stations south of Sydney Harbour. However, similar emission spectra were observed for all samples collected from stations both north and south of Sydney Harbour. Nevertheless, indicator bacteria densities for southern stations were observed to be better correlated with fluorescence intensities on particular days. The stations north of Sydney Harbour are believed to be impacted only by the one outfall at North Head. However the system south of Sydney Harbour is more complex. The southern stations are known to be impacted by any, or all of the three major outfalls at Bondi, Malabar, and North Head. Fluorescence can be used to determine effluent concentration in ocean waters where the origin of the effluent is known. There should also be opportunities for the development of fluorescence as an alternative indicator for “real time” public health monitoring of recreational waters.

Spatial and temporal distribution of phytoplankton and primary production in the western Bransfield Strait region

Studies on phytoplankton were one component of the multi-disciplinary RACER program which had 69 stations within a 100 × 250-km rectangle in the southwestern Bransfield Strait and contiguous waters. Data were acquired during eight cruises between December 1986 and March 1987. All deep stations north of the continental shelf break were low in phytoplankton biomass (<41 mg Chl a m −2) and in rates of primary production (mean of 0.34 g C m −2 day −1) as compared to stations in continental shelf waters. Phytoplankton biomass exceeded 700 mg Chl a m −2 at some stations in shelf waters, with rates of primary production in December exceeding 3.0 g C m −2 day −1. The mean rate of primary production at the shelf stations for the 4-month period was 1.05 g C m −2 day −1. Greatest phytoplankton biomass was found at stations in Gerlache Strait and in nearby Bransfield Strait. Dramatic seasonality in phytoplankton crop size was observed, as massive blooms during December to January declined abruptly to low levels in February to March. As the decrease in phytoplankton biomass was much more abrupt than the corresponding decrease in incident solar irradiation, light does not appear to be the major factor involved in decline of the bloom. Except for stations in Gerlache Strait, nutrient levels remained sufficiently high (> 10 μM inorganic nitrogen) that nutrient depletion is not likely to have caused the rapid decline of the phytoplankton bloom. Grazing, sinking and advection all appear to be important mechanisms of massive bloom decline. Phytoplankton populations appeared to be low-light adapted, as they showed low P max values (1.1 mg C mg Chl a −1 h −1), low saturating ligh values ( I k ∼ 18 μEins m −2 s −1), high initial slope [ α = 0.06 (mg C mg Chl a −1h −1/ μEin m −2 s −1)] and a compensation point for net light-activated fixation of CO 2 of ≈ 1.0 μEin m −2 s −1.

THERMAL PATTERNS OF PACIFIC SOUTH AMERICA ASSOCIATED WITH EL NIÑTO/SOUTHERN OSCILLATION

AbstractThis study quantifies the magnitude of temperature anomalies associated with extremes of the Southern Oscillation (SO) for 12 long‐record stations and five shorter‐record stations along the west coast of South America. Analysis of t‐tests indicates that nine stations north of 35°S have a strong inverse relationship between their mean annual temperature and the sign of the Tahiti–Darwin Southern Oscillation Index (SOI). Significant inverse relationships are determined between the phase of the Southern Oscillation and (i) summer temperatures (five stations), (ii) autumn temperatures (eight stations), (iii) winter temperatures (eight stations), and (iv) spring temperatures (four stations) for the region north of 35°S. In particular, the northern mid‐latitude stations (18°S–33°S) along the‐west coast of South America show a pronounced seasonal pattern in temperature differences between extremes in the SO. The summer temperature increases associated with negative SOI values may be due to warm air advection from the equatorial regions. The increase in winter temperatures may be caused by warm air advection from the mid‐latitudes associated with greater zonal flow caused by weakening of the South Pacific subtropical high. Stations south of 35°S display little temperature contrast between extremes of the SO.

Correlations of Sea Level Pressure Fields for Objective Analysis

Spatial correlations for sea level pressures, during the Canadian Atlantic Storms Program of January-April 1986, were computed. We initially modeled these correlations using isotropic negative squared exponential, and second- and third-order autoregressive correlation functions. Allowances for variations due to latitude were made by partitioning the pressure stations north of 44°N from those south of 44°N and parameterizing observed correlations in each group using isotropic correlation functions. Tomporal variations were accommodated by separating pressure reports of the period early January to middle February from the period middle February to early April and parameterizing as before. Anisotropy was displayed by modeling the whole dataset using anisotropic second- and third-order autoregressive correlation functions. These model correlation functions, which are used in optimal statistical estimation methods for the assimilation of data, were related to dynamical processes of the planetary boundary layer.

Underground connection line between south and north stations Beijing : Gao Quqing; Tu Shugen Proc 6th Australian tunnelling conference, Melbourne, March 1987V1, P89–95. Publ Parkville: AusIMM, 1987

Underground connection line between south and north stations Beijing : Gao Quqing; Tu Shugen Proc 6th Australian tunnelling conference, Melbourne, March 1987V1, P89–95. Publ Parkville: AusIMM, 1987

A comparison of SAGE 1, SBUV, and Umkehr ozone profiles including a search for Umkehr aerosol effects

Using a spatially weighted average of SAGE 1 measurements, we find 337 colocated SAGE 1 and Umkehr ozone profiles. The total column ozone above 250 mbar measured by SAGE 1 averages 5% higher than that measured by Umkehr. This difference is concentrated in the lower stratosphere and, for latitudes poleward of 30°N, the difference depends on both the total column ozone and the season. The difference, however, is insensitive to the stratospheric aerosol optical depth measured by SAGE 1. Intercomparison of SAGE 1, SBUV, and Umkehr ozone at stations north of 30° indicates that in layer six (approximately 10 mbar) Umkehr values are approximately 10% high, and in layer eight (approximately 3 mbar) SBUV ozone is approximately 10% high. In the upper stratosphere, the SAGE 1‐ Umkehr ozone differences are small for low stratospheric aerosol optical depth cases (less than 0.025 at 0.3 μm) but vary from −3% in layer six to −8% in layer nine for high optical depth cases (greater than 0.025). This tendency is opposite to that predicted by empirical studies, which included large amounts of volcanic aerosols, and by theoretical model studies.

The use of precipitation data to identify soil moisture patterns and the growing seasons in Eastern Kenya

Eight stations with 36 years of rainfall record were selected in the dry region of Kenya, east of 37°E longitude, so as to study the nature of the moisture patterns during the Short and the Long rains (October through June). The rainfall data were reduced to soil moisture based upon area-wide assumptions concerning soil characteristics. The start, end and duration of the rainy seasons were determined and tested for normality of distribution using a 10 mm soil moisture threshold value at each station. Mean-year conditions were computed and comparisons were made between the two growing seasons at each station and among all the stations. Stations were grouped according to the magnitude of the coefficient of determination between the start and duration of the seasons with sufficient soil moisture for plant growth, and regression equation were developed to predict season duration using the starting dates. Equations are also derived to estimate the probable length of the season for various levels of soil moisture requirements. The important findings that have relevance for the farmer in the area so as to assist in his decision-making are: (1) The distributions of the start, end and duration of the growing seasons are not significantly skewed or significantly different from the normal distribution; (2) the start and end times of the Short rains season show a southward trend; (3) the Short rains growing season is found to last longer, be more reliable, and to have a higher soil moisture content than the Long rains season for stations located south of the equator; and (4) the opposite is true for stations north of the equator.

Fluoride distribution in the Jordan gulf of Aqaba (Red Sea)

In order to evaluate the magnitude and effect of phosphate (fluorapatite) rock particles on the distribution of fluoride in the Jordanian sector of the Gulf of Aqaba, sea water and sediment samples were collected from six stations north and south of Aqaba Port. The fluoride concentrations of the water and sediments were determined, together with the concentrations of calcium, calcium carbonate, total phosphorus, magnesium and organic matter in the sediments. Normal fluoride concentrations were found in the sea water samples, whereas abnormally high values were found in the phosphate-polluted sediments. These findings and the correlations between fluoride concentrations and those of other measured parameters are discussed.

The Composition of Phytobezoars (Felt Balls) from Sheep in Western Australia.

Bezoars (felt balls) from sheep on Jeedamya and Adelong stations north of Kalgoorlie, and on a farm near York, Western Australia, were examined microscopically and found to consist principally of a dense mass of sclerenchyme fibres. In size, colour and texture the bezoars closely resemble bezoars composed of plant epidermal hairs, described by South African workers. Acacra ramulosa is suggested as the likely source of bezoar fibres at Jeedamya and Adelong. The source of fibres from York was not determined. The identification of plant species from which bezoar fibres are derived may make possible the control of bezoariasis by grazing management.

Time series analyses of annual rainfall over India

The available rainfall series extending to more than 100 years for 23 stations representing different parts of India have been examined with different types of low pass filters in order to find out trends and periodicities in these series. The long period trend shown by some of the series has been compared with that shown by sunspot numbers the series of which from 1940 onwards was treated with the same low pass filter. The rainfall series have also been treated with band pass filter and power spectrum analysis for finding out of periodicities in them. It is seen that rainfall of west coast stations north of Trivandrum as well as the sunspot cycles have shown an increasing trend from the beginning of the century till the sixties, the trends for Veraval, Bombay, Ratnagiri and Vengurla being statistically significant. Other results of the study have been given in the conclusion.