bluuebunny/crossref_metadata_2025 huggingface dataset:
Die deutsche Version des AISS: Psychometrische Kennwerte und Befunde zur Reliabilität und Validität
Authors: Roth Marcus
Published: May 2003

Zusammenfassung: Als alternatives Meßinstrument zu der bekannten, in den letzten Jahren jedoch stark kritisierten Sensation Seeking Scale - Form Five (SSS-V) von Zuckerman et al. (1978) wurde von Arnett (1994) das Arnett Inventory of Sensation Seeking (AISS) vorgelegt, das Intensität und Neuigkeit als die beiden Hauptdimensionen des SS-Merkmals postuliert. In der vorliegenden Untersuchung wurde die deutsche Fassung des Instruments bezüglich psychometrischer Kennwerte, Reliabilität (interne Konsistenz) und Validität überprüft. 228 Studierende im Alter zwischen 19 und 23 Jahren bearbeiteten neben dem AISS, das NEO-Fünf-Faktoren-Inventar (NEO-FFI) sowie die SSS-V. Die Befunde stützen die angenommene zweidimensionale Struktur, zeigen jedoch auch, daß zur Verbesserung der internen Konsistenz der Verzicht auf einige Items notwendig erscheint. Hinweise auf die Kriteriumsvalidität ergaben sich unter anderem aus der Vorhersage des Drogenkonsums und riskanten Fahrverhaltens. Die Ergebnisse einer Analyse der konvergenten und diskriminanten Validitäten des Verfahrens waren sehr zufriedenstellend. Insgesamt ergaben die Ergebnisse eine hinreichende Unterstützung für die Validität des AISS, indizieren jedoch auch die Notwendigkeit einiger Modifikationen.
Zur internen Struktur des globalen Selbstwertgefühls nach Rosenberg
Authors: von Collani Gernot , Herzberg Philipp Yorck
Published: May 2003

Zusammenfassung: Es wird eine Prüfung der internen Struktur einer deutschsprachigen Fassung der Skala zum globalen Selbstwertgefühl nach Rosenberg vorgenommen. Explorative und vor allem konfirmatorischen Faktorenanalysen zeigen, dass das Konstrukt des globalen Selbstwertes, operationalisiert mittels der Selbstwert-Skala von Rosenberg, als mehrdimensional angenommen werden muss. Es finden sich Belege für ein Modell mit den Komponenten “Selbstabwertung” und “Selbstakzeptanz”, letztere unterteilt in zwei Unterkomponenten. Validitätshinweise für dieses Modell werden präsentiert. Unterschiedlich ausgeprägtes Sprachverständnis der Probanden scheint allerdings nicht für die bivariate Struktur verantwortlich zu sein. Ein einheitliches Konstrukt “Selbstwertgefühl” kann jedoch zumindest auf der Stufe eines Faktors 2.Ordnung angenommen werden.
Face-ism Effect and Head Canting in One's Own and Others' Photographs
Authors: Costa Marco , Bitti Pio Enrico Ricci
Published: May 2003

The influence of face-ism (i.e., the attribution of positive characteristics to people in close-up shots) in photographs picturing oneself and others was assessed in 51 female and 28 male university students. Three different shots (portrait, half-figure, and whole figure) were taken of all subjects. After rating their own physical attractiveness, subjects were asked to assess attractiveness and rate each shot on an analog scale. The same procedure was used for the pictures of two individuals, chosen randomly from those previously tested (one male and one female) and with whom the subject was not familiar. Analyses with ANOVA revealed that unfamiliar male subjects received lower evaluations in attractiveness compared to self and unfamiliar female rating. As to pictures of nonfamiliar individuals, there was a clear preference for short-distance shots (portrait), whereas for pictures portraying oneself there was a tendency to prefer medium-distance shots (half-figure, whole figure). Multiple regression analyses revealed a positive relationship between the general attractiveness evaluation of the subject and the rating of each shot for both one's own and others' photographs. Seventy-one percent of all subjects, independent of gender, exhibited head canting with a mean angle of 5.1°. This is much higher than that found in natural settings and media portraits and may be explained by the sense of embarrassment and discomfort usually experienced in a photographic setting.
Coping with Loneliness
Authors: Rokach Ami , Bacanli Hasan , Ramberan Gina
Published: May 2003

The present study examined the influence of cultural background on coping with loneliness. 711 participants from Canada, 568 from Turkey, and 389 from Argentina answered an 86-item questionnaire examining the beneficial strategies they used to cope with loneliness. Those strategies included acceptance and reflection, self-development and understanding, social support network, distancing and denial, religion and faith, and increased activity. Results indicated that cultural background affects the strategies one uses to cope with loneliness. North Americans had the highest mean scores on all six subscales, while Argentinians had the lowest scores on five out of the six subscales.
Analysis of satellite gravity and bathymetry data over Ninety‐East Ridge: Variation in the compensation mechanism and implication for emplacement process
Authors: Tiwari V. M. , Diament M. , Singh S. C.
Published: May 2003

We investigate the mode of compensation, emplacement history and deep density structure of the Ninety‐East Ridge (Indian Ocean) using spectral analyses and forward modeling of satellite gravity and bathymetry data. We find that the northern (0–10°N) and the southern (20–30°S) parts of the ridge are flexurally compensated with an effective elastic thickness >15 km, whereas the central part (0–20°S) is locally compensated. Furthermore, we find that for a part of central block (10–20°S, over Osborn Knoll) the compensation depth is unreasonably very high (30–40 km). Therefore we favor a model with subsurface loading and interpret this to be due to underplating of mafic material at the base of the crust, a hypothesis that is supported by seismic results and direct modeling of gravity data along some profiles. These results suggest that the northern and southern parts of Ninety‐East Ridge were emplaced off to a ridge axis compared to the central one, which might have been emplaced on or near a spreading center. Locally compensated large topography, thick underplated crust in the central part (near Osborn Knoll), might result from an interaction of a hot spot with the extinct Wharton spreading ridge.
Upper mantle beneath Southeast Asia from S velocity tomography
Authors: Lebedev Sergei , Nolet Guust
Published: May 2003

We present a three‐dimensional, S velocity model of the SE Asian‐western Pacific upper mantle with 400‐km lateral resolution. Using the novel Automated Multimode Inversion technique, we processed 4038 vertical‐component seismograms and extracted 22,708 linear equations with uncorrelated uncertainties that constrain upper mantle structure. We used time‐frequency windows to select signal with negligible proportion of scattered energy. The windows included the fundamental Rayleigh mode and S and multiple S waves. The observed range of S velocity variations is the widest (17–18%) in the upper 150 km of the mantle. High‐velocity continental roots can reach beyond the present extent of the overlying Archean‐Proterozoic crust by 500 km. Beneath some Precambrian units the roots are absent, which can be attributed to deformation and gradual destruction of the ancient lithosphere. At 120–150 km, S velocity beneath some cratons reaches 4.8 km/s; this can be accounted for by thermal and compositional effects. Beneath the Hainan Island area a low‐velocity anomaly is observed from near the surface to the bottom of our model; the hot spot‐type volcanism here may be caused by the deep‐mantle Hainan plume. A low‐velocity mantle domain underlies the south central Sea of Japan, surrounded on the surface by intraplate volcanoes. A deep‐seismicity gap is present near 40°N in the Pacific slab subducting below and may result from a plume‐slab interaction. A high‐velocity anomaly is present in the transition zone beneath the northern boundary of the Yangtze Craton. We propose that the anomaly corresponds to subducted continental lithosphere, stagnant atop the 660‐km discontinuity.
A constitutive scaling law and a unified comprehension for frictional slip failure, shear fracture of intact rock, and earthquake rupture
Authors: Ohnaka Mitiyasu
Published: May 2003

It is widely recognized that some of the physical quantities inherent in a rupture are scale‐dependent, and the scale dependence is one of the most no facts and features of rupture phenomena. The paper addresses how such scale‐dependent shear rupture of a broad range from laboratory‐scale frictional slip failure and shear fracture of intact rock to field‐scale rupture as an earthquake source can be unified by a single constitutive law. Noting that the earthquake rupture is a mixed process between frictional slip failure and the shear fracture of intact rock, it is concluded that the constitutive law for the earthquake rupture be formulated as a unifying law that governs both frictional slip failure and shear fracture of intact rock. It is demonstrated that the slip‐dependent constitutive law is such a unifying law, and a constitutive scaling law is derived from laboratory data on both frictional slip failure and shear fracture of intact rock. This constitutive scaling law enables one to provide a consistent and unified comprehension for scale‐dependent physical quantities inherent in the rupture, over a broad range from small‐scale frictional slip failure and shear fracture in the laboratory to large‐scale earthquake rupture in the field.
Geochemical variability in a single flow from northern Iceland
Authors: Maclennan J. , McKenzie D. , Hilton F. , Gronvöld K. , Shimizu N.
Published: May 2003

Compositional variability is present for almost every element analyzed in 70 whole rock samples and 40 olivine‐hosted melt inclusions from the Borgarhraun lava flow in NE Iceland. The variation of incompatible element concentrations can be produced by incomplete mixing of fractional melts, while the compatible element variations in the whole rock samples can be explained by addition/removal of crystals found in the flow. The melt inclusion incompatible element compositions are more variable than the whole rock compositions, and the magnitude of variability of the whole rock samples can be matched if each hand specimen is made of magma that was formed by mixing of 20–30 batches of melt with the composition of the inclusions. Clinopyroxene barometry and the major element composition of the whole rock samples suggest that mixing took place at pressures of ∼0.9 GPa in sub‐Moho magma chambers. The spatial distribution of the concentrations of incompatible elements is not random in Borgarhraun and samples with a separation of <4 km have concentrations that are more similar than expected from a random distribution of geochemistry. This separation distance corresponds to a lava volume of 0.014–0.14 km3. This volume may be controlled by magma mixing and episodic eruption of melts from a sub‐Moho chamber. The concentration variations of compatible elements with position in the flow are little different to those expected for random variation. It is likely that the crystal removal and addition processes that control major element compositions generate variability on short length scales.
Carbon dioxide along WOCE line A14: Water masses characterization and anthropogenic entry
Authors: Ríos A. F. , Álvarez‐Salgado X. A. , Pérez F. F. , Bingler L. S. , Arístegui J. , Mémery L.
Published: May 2003

The meridional WOCE line A14, just east of the South Atlantic Mid‐Atlantic Ridge, was surveyed during the austral summer of 1995 from 4°N to 45°S. Full‐depth profiles of pH, total alkalinity (TA), and total inorganic carbon (CT) were measured, allowing a test of the internal consistency of the CO2 system parameters. The correlation between CT measured and calculated from pH and TA was very good (r2 = 0.998), with an insignificant average difference of 0.1 ± 3.0 μmol kg−1 (n = 964 data). CO2 certified reference materials (CRMs) and a collection of selected samples subsequently analyzed at the Scripps Institution of Oceanography were used to assess the accuracy of our measurements at sea with satisfactory results. The three measured CO2 system variables were then used to identify the characteristic array of zonal flows throughout the South Atlantic intersected by A14. Equatorial, subequatorial, subtropical, and subantarctic domains were identified at the depth range of the surface water, South Atlantic Central Water (SACW), Antarctic Intermediate Water (AAIW), Upper Circumpolar Water (UCPW), North Atlantic Deep Water (NADW) and Antarctic Bottom Water (AABW). The nonconservative CO2 system parameters (pH, TA, CT) have been useful in identifying the transition from aged subequatorial to ventilated subtropical surface, central and intermediate waters. They have been identified as good tracers of the zonal circulation of NADW, with marked flows at the equator, 13°S, and 22°S (the “Namib Col Current”) and the sharp transition from UNADW to UCPW at 23°S. The anthropogenic CO2 inventory (CANT) was estimated and compared with CFC‐derived apparent ages for different water masses along A14. The anthropogenic entry reached maximum in the relatively young and ventilated subantarctic and subtropical domains where AAIW was the most efficient CO2 trap. The calculated annual rate of CANT entry by AAIW was 0.82 μmol kg−1 y−1, in agreement with the annual rate estimated from the equilibrium between the atmospheric pCO2 increase and the upper mixed layer.
Atmospheric teleconnections involving the Southern Ocean
Authors: Carleton Andrew M.
Published: May 2003

I review the characteristic patterns of low‐frequency (interannual and subdecadal) variation in atmospheric circulation over the Southern Hemisphere (SH) extratropics and their climatic associations (e.g., temperature, precipitation, winds, sea surface temperatures (SSTs), and sea ice conditions) for the Southern Ocean. The considerable spatial and temporal limitations of the observational database have strongly conditioned the pace of our understanding of SH teleconnections, particularly for the Pacific sector, where the tropical El Niño–Southern Oscillation (ENSO) exerts a dominant influence: an ENSO signal appears in the intensity interannual variations of the Amundsen Sea mean low pressure (ASL), jet streams, and long waves. These variations comprise the so‐called Pacific–South America (PSA) teleconnection. Patterns of low‐frequency variability in SH circulation that are mostly extratropical in origin, but which can interact with ENSO, are dominated by the zonally symmetric “high‐latitude mode” or Antarctic Oscillation (AAO). The AAO involves an alternation of atmospheric mass between middle and high southern latitudes. A zonally asymmetric mode of wave number 1 is represented by an oscillation in pressure/height between Australian and South American sectors, depicted by a “Trans‐Polar” circulation index. A significant wave number 2 oscillation in the coupled atmosphere–ocean–ice system or Antarctic circumpolar wave (ACW) has a similar periodicity to ENSO and is strongest in the Pacific–SW Atlantic sectors. Atmospheric teleconnections involving the Southern Ocean, including those to ENSO, show evidence of recent changes, and the climatic implications of these are discussed.
Model study of the cross‐frontal water exchange on Georges Bank: A three‐dimensional Lagrangian experiment
Authors: Chen Changsheng , Xu Qichun , Beardsley Robert C. , Franks Peter J. S.
Published: May 2003

Characteristics of the cross‐frontal water exchange over Georges Bank are investigated through a sequence of numerical model experiments featuring realistic three‐dimensional (3‐D) bathmetry, bi‐monthly averaged climatological stratification, tidal forcing, and mean and observed wind‐forcing. The model used in this study is the ECOM‐si version of the Blumberg and Mellor [1987] primitive equation model with Mellor‐Yamada [1982] level 2.5 turbulence closure. The model domain includes Georges Bank and the Gulf of Maine, and is forced at the open ocean boundary by the semidurnal M2 tide. Fluid particles were tracked in the 3‐D, time‐dependent Eulerian flow field to examine the Lagrangian flow field, and passive tracer experiments were conducted to investigate the relative roles of advection and turbulent diffusion on cross‐frontal exchange. Two distinct paths for the on‐bank water movement were detected on Georges Bank: one is over the northwestern flank of the bank where the bottom topography changes sharply in both along‐ and cross‐bank directions, and the other is near the bottom around the bank where the tidal mixing front is located. Over the northern flank, the cross‐bank component of the Lagrangian residual current is generally opposite in direction to that of the Eulerian residual current, resulting in an on‐bank, cross‐frontal water transport near the bottom. Over the southern flank, the near‐bottom water tends to converge toward the tidal mixing and shelf‐break fronts, so that the near‐bottom flow over the shelf between these two fronts is divergent. The response to wind‐forcing varied with ambient stratification and water depth. In winter, strong winds can drive a significant off‐bank water transport, tending to “wash out” the bank. In summer, winds are generally too weak to alter the general pattern of tidal‐driven particle motion within the mixed region on the crest of the bank and the surrounding tidal mixing front. Some wind‐driven off‐bank transport occurs near the surface in the stratified region on the outer southern flank, but this has little influence on water movement near the bottom. Passive tracer experiments reveal that the net cross‐frontal water flux near the bottom is caused primarily by advection and horizontal diffusion. Tidal‐induced vertical diffusion tends to make the tracer mix rapidly upward, thus reducing the percent of the cross‐frontal flux due to advection. Our new model results are consistent with previous model studies of Georges Bank, and agree in general with drifter and dye patches observed in the U.S. GLOBEC NW Atlantic/Georges Bank program.
Biogeochemistry of a Southern Ocean plankton ecosystem: Using natural variability in community composition to study the role of metazooplankton in carbon and nitrogen cycles
Authors: Priddle Julian , Whitehouse Michael J. , Ward Peter , Shreeve Rachael S. , Brierley Andrew S. , Atkinson Angus , Watkins Jonathan L. , Brandon Mark A. , Cripps Geoffrey C.
Published: May 2003

The pelagic ecosystem around the island of South Georgia is subject to significant interannual variability, and changes in zooplankton community composition can be used as natural ecosystem experiments to examine biogeochemical cycles. The biomass of the large euphausiid Antarctic krill may range from ca. 2 to 150 g fresh mass (FM) m−2. When krill biomass is low, copepod biomass may be correspondingly higher and overall zooplankton biomass remains more or less unchanged. Krill are omnivorous, feeding facultatively either as grazers on microplankton or as predators on smaller zooplankton. This leads to complex feedbacks within the plankton. A simple model of the phytoplankton–copepod–krill system is used to simulate two scenarios of zooplankton composition. For the “low krill‐high copepod” scenario, the model predicts higher phytoplankton biomass and production, lower mixed layer (ML) ammonium, nitrate and silicate concentrations, and higher detrital carbon production than in the “high krill‐low copepod” scenario. Nitrogen cycling provides the most explicit demonstration of the differences between the scenarios. For the “low krill‐high copepod” scenario, ML ammonium concentration decreased by 25% over 20 days, but excretion by metazooplankton supplied 30% of phytoplankton nitrogen demand. In the “high krill‐low copepod” scenario, ML ammonium only declined by 10% over 20 days, but metazooplankton excretion was much lower, at 10% of phytoplankton N demand. These predictions are compared with data from several surveys covering krill biomass in the range 10–55 g FM m−2. Phytoplankton chlorophyll biomass is negatively related to krill biomass, and ML nutrients are positively correlated with krill biomass in these data. Both observations and model results suggest that variation in biogeochemical carbon and nitrogen cycles in the South Georgia pelagic ecosystem is determined largely by changes in zooplankton community composition and its impact on phytoplankton dynamics.
Helium 3 and dissolved oxygen balances in the upper waters of the Weddell Sea: Implications for oceanic heat fluxes
Authors: Hohmann R. , Schlosser P. , Huber B.
Published: May 2003

We present helium 3 (3He) and dissolved oxygen (DO) distributions in the upper waters of the central Weddell Sea obtained from samples collected during the Winter Weddell Sea Project (WWSP, July to September 1986), and the Antarctic Zone Flux Experiment (ANZFLUX, July to August 1994). The data are discussed in terms of apparent entrainment rates of Weddell Deep Water (WDW) into the Winter Mixed Layer (WML) and the associated apparent heat flux. The fraction of WDW in the WML derived from the 3He excess (Δδ3He) and DO deficit in the mixed layer increases with latitude and reaches 10–20% at 68°S. The corresponding apparent heat flux during the winter entrainment period is 14 ± 4 W m−2, and the apparent annual heat flux is 6 ± 4 W m−2. Significantly larger heat fluxes (winter ocean heat flux of 25 W m−2; average annual heat flux of 15 W m−2) are observed near Maud Rise and in the region southwest of the rise in features that are associated with a Taylor column that apparently forms over the seamount. The entrainment rates and heat fluxes obtained from a one‐dimensional numerical model exceed those calculated from the WDW fraction in the WML by about a factor of two, mainly because of the effect of gas exchange through leads on the mass balance of 3He and DO in the WML. The best agreement between model calculations performed for 62.5°S, 65°S, and 67.5°S and observations is achieved for entrainment rates of 25–35 m yr−1, 30–40 m yr−1, and 35–45 m yr−1, respectively. Daily entrainment rates are practically identical (0.28–0.39 m d−1) for the three latitudes. Corresponding simulated heat fluxes for the winter entrainment period and the annual average are 36–50 W m−2 and 10–17 W m−2, respectively. Extrapolation of the annual average heat flux to the seasonally ice‐covered Weddell Sea yields a value of 0.04–0.07 PW.
Two‐dimensional numerical simulations of Arctic leads: Plume penetration height
Authors: Zulauf Michael A. , Krueger Steven K.
Published: May 2003

During the Arctic winter, leads can be a significant source of heat and water vapor for the atmosphere due to the extreme temperature differences between the sea surface and the atmosphere. Because of their relatively small scales, however, these openings in the pack ice cannot be explicitly resolved by large‐scale models. In the present study, a two‐dimensional cloud‐resolving model is employed to examine the development of the convective plumes that can form in the vicinity of leads. Two important considerations with respect to leads are the enhanced surface fluxes over the warm water surface and the height to which the resulting plumes penetrate, which represents the depth of the atmosphere that is directly affected by these enhanced fluxes. The dependence of plume height on ambient wind speed, orientation, and lead width is investigated. Comparisons to earlier large‐eddy simulation results generally show good agreement, while comparisons with simple analytical expressions for plume height show good agreement for cases with no cross‐lead large‐scale flow and poor agreement for cases with significant cross‐lead winds. Sensitivity experiments are run to gauge the impacts of interactive microphysical and radiative processes. When these processes are included in the simulations, plume depths increase up to 20% over the baseline case, which is in general agreement with earlier one‐dimensional results. Finally, it was found that by generalizing the surface buoyancy flux to include latent and radiative fluxes, the analytical expression for plume height could be successfully applied to the case where there is no large‐scale cross‐lead wind.
Spatial/temporal patterns in Weddell gyre characteristics and their relationship to global climate
Authors: Martinson Douglas G. , Iannuzzi Richard A.
Published: May 2003

We examine the spatiotemporal variability of the upper ocean sea ice system of the Atlantic sector of the Southern Ocean subpolar seas (Weddell gyre) and the nature of its covariability with extrapolar climate. To systematically evaluate the sporadic and sparse distribution of subpolar data, we employed an optimal analysis involving empirical orthogonal functions (EOFs). The EOFs reveal that the pattern of spatial covariability of Weddell gyre characteristics is dominated by high interannual variability near the northern (circumpolar) rim of the gyre and lesser variability (10–20% of the variance) in the gyre's central core region. We find considerable, statistically significant teleconnections between subpolar and extrapolar climate. The dominant link is with El Niño–Southern Oscillation. Our analysis of the gyre characteristics suggest that during El Niño, the Atlantic subpolar (Weddell) gyre spins up while the eastern Pacific subpolar gyre spins down; the opposite occurs for La Niña. This regional subpolar response is consistent with recent GCM modeling analyses. These show that equatorial warm anomalies drive changes in the meridional and zonal atmospheric circulation cells. This results in opposite shifts of the subpolar jets in the Pacific and Atlantic oceans that lead to a change in the interaction (especially in cyclones) between the subtropical and polar front jets in those basins, and ultimately in the cyclonic forcing of the subpolar gyres. We also find that the Weddell gyre interior upper ocean characteristics covary positively with sea ice extent in the Atlantic region and negatively with the sea ice extent in the Amundsen/Bellingshausen regions, reflecting a strong Antarctic dipole.
Global characterization of Rossby waves at several spectral bands
Authors: Polito Paulo S. , Liu W. Timothy
Published: May 2003

Global sea surface height anomaly signals from the TOPEX/Poseidon satellite altimeter from 1992 to 2000 are filtered into several spectral bands. These bands include propagating (Rossby, Kelvin, and tropical instability waves) and nonpropagating (annual and interannual basin‐scale variability and eddies) signals. These signals are decomposed through a series of finite impulse response band‐pass filters. Phase speed, period, wavelength, and amplitude are estimated. Signal‐to‐noise ratio, methodological errors, and natural variability are also estimated. Results are shown for the Pacific, Atlantic, and Indian basins for four Rossby wave components with periods between 3 and 24 months. Equatorial Kelvin waves and tropical instability waves are shown as peripheral results. The clearest and most energetic wave signals are generally observed for annual Rossby waves. Semiannual Rossby waves often have the largest amplitudes near the tropics. The Rossby wave phase speeds are in agreement with the linear theory, except for a ∼25% bias toward high speeds found in mid to high latitudes. This revitalizes the idea that on the average the Rossby wave signal in the ocean is in the form of free waves.
Mixed layer depth variability over the global ocean
Authors: Kara A. Birol , Rochford Peter A. , Hurlburt Harley E.
Published: May 2003

The spatial and monthly variability of the climatological mixed layer depth (MLD) for the global ocean is examined using the recently developed Naval Research Laboratory (NRL) Ocean Mixed Layer Depth (NMLD) climatologies. The MLD fields are constructed using the subsurface temperature and salinity data from the World Ocean Atlas 1994 [Levitus et al., 1994; Levitus and Boyer, 1994]. To minimize the limitations of these global data in the MLD determination, a simple mixing scheme is introduced to form a stable water column. Using these new data sets, global MLD characteristics are produced on the basis of an optimal definition that employs a density‐based criterion having a fixed temperature difference of ΔT = 0.8°C and variable salinity. Strong seasonality of MLD is found in the subtropical Pacific Ocean and at high latitudes, as well as a very deep mixed layer in the North Atlantic Ocean in winter and a very shallow mixed layer in the Antarctic in all months. Using the climatological monthly MLD and isothermal layer depth (ILD) fields from the NMLD climatologies, an annual mean ΔT field is presented, providing criteria for determining an ILD that is approximately equivalent to the optimal MLD. This enables MLD to be determined in cases where salinity data are not available. The validity of the correspondence between ILD and MLD is demonstrated using daily averaged subsurface temperature and salinity from two moorings: a Tropical Atmosphere Ocean array mooring in the western equatorial Pacific warm pool, where salinity stratification is important, and a Woods Hole Oceanographic Institute (WHOI) mooring in the Arabian Sea, where strongly reversing seasonal monsoon winds prevail. In the western equatorial Pacific warm pool the use of ILD criterion with an annual mean ΔT value of 0.3°C yields comparable results with the optimal MLD, while large ΔT values yield an overestimated MLD. An analysis of ILD and MLD in the WHOI mooring show that use of an incorrect ΔT criterion for the ILD may underestimate or overestimate the optimal MLD. Finally, use of the spatial annual mean ΔT values constructed from the NMLD climatologies can be used to estimate the optimal MLD from only subsurface temperature data via an equivalent ILD for any location over the global ocean.
Description of the Mesoscale Nonhydrostatic Chemistry model and application to a transboundary pollution episode between northern France and southern England
Authors: Tulet Pierre , Crassier Vincent , Solmon Fabien , Guedalia Daniel , Rosset Robert
Published: May 2003

The mesoscale air quality Mesoscale Nonhydrostatic Chemistry (Meso‐NH‐C) model is applied to a complex pollution episode over Western Europe during the period 11 to 12 August 1997. As observed in satellite pictures and as simulated, the complexity of this episode is related to the presence of anticyclonic clear‐sky areas and regions with deep convective activity in the simulation domain. A brief presentation of the model is made that covers in particular the on‐line coupling capability for calculating meteorological and chemical concentration fields at each time step. Then, emphasis is put upon the simulation of transboundary pollution fluxes from London to northern France in a zone of large horizontal wind gradients. Comparison with data from the French Agence De l'Environnement et de la Maitrise de l'Energie (ADEME) pollution network indicates that ozone concentrations and time of arrival of the pollution plume are correctly predicted at surface stations in northern France. A sensitivity analysis relying upon local ozone production and pollution transport has shown that ∼30% of ozone maxima levels could be attributed to regional transboundary fluxes.
Comprehensive mass modeling of the Moon from spectrally correlated free‐air and terrain gravity data
Authors: Potts Laramie V. , von Frese Ralph R. B.
Published: May 2003

A lunar crust‐to‐core mass model for the region ±64° latitude was developed using gravity components evaluated from available spherical harmonic gravity and topographic field models that include Lunar Prospector, Clementine, and earlier satellite observations. Terrain gravity effects were computed at 100‐km altitude in spherical coordinates from 1° topography (GLTM 2) by Gauss‐Legendre quadrature integration. Corresponding free‐air gravity anomalies (LP75G) were spectrally correlated with the terrain effects to differentiate the terrain‐correlated and terrain‐decorrelated free‐air components. The absence of correlation between these free‐air components was interpreted for a Moho that may involve over 120 km of relief, assuming the lunar crust was mainly compensated by its thickness variations. Lacking the strong regional gravity effects of the terrain, the terrain‐decorrelated anomalies may be interpreted for their subcrustal components on the basis of their correlation spectrum with the free‐air anomalies. Inversions of the subcrustal anomalies inferred boundary undulations for the core‐mantle, asthenosphere‐lithosphere, and middle‐upper mantle that are remarkably correlated with surface impacts. The elevated core topography revealed beneath the Procellarum basin is consistent with the uplifting effects of the Imbrium impact and the development of the great lunar hotspot. Topographic undulations inferred for the lower and middle mantle reflect the dichotomized thermal evolution of the lunar near and far sides during bombardment time. On the nearside the results support the development of relatively thinner and hotter lithosphere by mantle convection that facilitated the diapiric rise of magma and mare flooding of the basins. For the farside the results favor the development of thicker and cooler lithosphere by viscous entrainment of lower density material into the lower mantle that limited basin flooding.
Eastern Mediterranean surface water temperatures and δ18O composition during deposition of sapropels in the late Quaternary
Authors: Emeis K.‐C. , Schulz H. , Struck U. , Rossignol‐Strick M. , Erlenkeuser H. , Howell M. W. , Kroon D. , Mackensen A. , Ishizuka S. , Oba T. , Sakamoto T. , Koizumi I.
Published: May 2003

Water column stratification increased at climatic transitions from cold to warm periods during the late Quaternary and led to anoxic conditions and sapropel formation in the deep eastern Mediterranean basins. High‐resolution data sets on sea‐surface temperatures (SST) (estimated from U37k′ indices) and δ18O of planktonic foraminifer calcite (δ18Ofc) across late Pleistocene sapropel intervals show that δ18Ofc decreased (between 1 and 4.6‰) and SST increased (between 0.7° and 6.7°C). Maximal δ18Oseawater depletion of eastern Mediterranean surface waters at the transition is between 0.5 and 3.0‰, and in all but one case exceeded the depletion seen in a western Mediterranean core. The depletion in δ18Oseawater is most pronounced at sapropel bases, in agreement with an initial sudden input of monsoon‐derived freshwater. Most sapropels coincide with warming trends of SST. The density decrease by initial freshwater input and continued warming of the sea surface pooled fresh water in the surface layer and prohibited deep convection down to ageing deep water emplaced during cold and arid glacial conditions. An exception to this pattern is “glacial” sapropel S6; its largest δ18Oseawater depletion (3‰) is almost matched by the depletion in the western Mediterranean Sea, and it is accompanied by surface water cooling following an initially rapid warming phase. A second period of significant isotopic depletion is in isotope stage 6 at the 150 kyr insolation maximum. While not expressed as a sapropel due to cold SST, it is in accord with a strengthened monsoon in the southern catchment.
Singular value decomposition methods for wave propagation analysis
Authors: Santolík O. , Parrot M. , Lefeuvre F.
Published: May 2003

We describe several newly developed methods for propagation analysis of electromagnetic plasma waves. We make use of singular value decomposition (SVD) technique and we determine the wave vector direction, ellipticity and directions of axes of the polarization ellipse, wave refractive index, transfer function of electric antennas, estimators of the planarity of polarization, and electromagnetic planarity. Simulations of Z‐mode waves, which simultaneously propagate with different wave vectors, indicate that the SVD methods give reasonable results even if the assumption on the presence of a single plane wave is invalid. Simulations of whistler mode waves show that these methods can be used to recognize cases when the waves simultaneously propagate with wave vectors in two opposite hemispheres. Finally, we show an example of analysis of natural whistler mode and Z‐mode emissions measured in the high‐altitude auroral region by the MEMO experiment onboard the INTERBALL spacecraft.
Simultaneous MST radar and radiosonde measurements at Gadanki (13.5°N, 79.2°E) 1. Causative mechanism and characteristics of radar backscatterers at VHF
Authors: Jain A. R. , Ghosh A. K. , Sivakumar V. , Kumar K. K.
Published: May 2003

Simultaneous MST radar and radiosonde observations have been carried out from Gadanki (13.5°N, 79.2°E), a tropical station in India. The radar measurements are used to obtain winds, vertical shear of horizontal winds (S), reflectivity (η), aspect sensitivity and horizontal correlation length (ζ) of the radar backscatterers. The radiosonde measurements of pressure, temperature and humidity are utilized for the computations of Brunt Vaisala frequency (N) and potential refractive index gradient (M). These measurements are used to understand the characteristics of the radar backscatterers in terms of prevailing background atmospheric conditions. Observations show strong vertical shears of horizontal winds in the height range of 16–18 km, at the upper edge of the tropical easterly jet (TEJ) associated winds. Results show that these shears and N2 both contribute to enhance the echo power in oblique directions (χ = 10°). The oblique beam observed enhancement of echo power, due to enhanced wind shears, is noticed to be confined to a narrow height range and associated backscatterers are more or less isotropic. At the height where N2 (or MD2) contribution to oblique echo power is significant, the radar backscatterers appear to be relatively more anisotropic with the horizontal correlation length (ζ) of 16–20 m. Present observations thus bring out clearly that even at oblique beam with zenith angle χ = 10° contribution of enhanced N2 to radar reflectivity (η) from refractivity structure with correlation length of ∼10–20 m can be very significant especially at the height above 17.5 km. These results have to be necessarily taken into account while interpreting the observed radar reflectivity observations.
Scattering from dielectric frequency selective structures
Authors: Forslund O. , Karlsson A. , Poulsen S.
Published: May 2003

A plane wave impinges on a laterally double‐periodic inhomogeneous lossy dielectric structure. Using a wave splitting approach, and an expansion of the fields and permittivity in entire domain basis functions, the scattered fields are determined via a propagator. The formulation is originally intended for constitutive parameters which vary continuously but is here applied to structures with an abruptly varying permittivity. The method resembles the so called coupled‐wave analysis method. Calculated results are compared with experimental data for a slab with domains of a piecewise homogeneous permittivity. The agreement is good considering the error sources in the experiment. The results are compared with calculated results obtained by an entirely different method showing very good agreement for the examples given. The method is also used on a pyramidal absorber‐like structure.
Modeling the effects of ionospheric scintillation on GPS/Satellite‐Based Augmentation System availability
Authors: Conker Robert S. , El‐Arini M. Bakry , Hegarty Christopher J. , Hsiao Thomas
Published: May 2003

Ionospheric scintillation is a rapid change in the phase and/or amplitude of a radio signal as it passes through small‐scale plasma density irregularities in the ionosphere. These scintillations not only can reduce the accuracy of GPS/Satellite‐Based Augmentation System (SBAS) receiver pseudorange and carrier phase measurements but also can result in a complete loss of lock on a satellite. In a worst case scenario, loss of lock on enough satellites could result in lost positioning service. Scintillation has not had a major effect on midlatitude regions (e.g., the continental United States) since most severe scintillation occurs in a band approximately 20° on either side of the magnetic equator and to a lesser extent in the polar and auroral regions. Most scintillation occurs for a few hours after sunset during the peak years of the solar cycle. Typical delay locked loop/phase locked loop designs of GPS/SBAS receivers enable them to handle moderate amounts of scintillation. Consequently, any attempt to determine the effects of scintillation on GPS/SBAS must consider both predictions of scintillation activity in the ionosphere and the residual effect of this activity after processing by a receiver. This paper estimates the effects of scintillation on the availability of GPS and SBAS for L1 C/A and L2 semicodeless receivers. These effects are described in terms of loss of lock and degradation of accuracy and are related to different times, ionospheric conditions, and positions on the Earth. Sample results are presented using WAAS in the western hemisphere.
Dry deposition of trace elements to the western North Atlantic
Authors: Arimoto R. , Duce R. A. , Ray B. J. , Tomza U.
Published: May 2003

Data for Al, Fe, Na, Sb, Se V, and Zn in aerosol particles from Bermuda are used in combination with parameterized dry deposition velocities to investigate trace element recycling on atmospheric sea salt. During July and August, which are in the high dust season, >10% of the monthly mean aerosol Na can be ascribed to crustal sources rather than sea salt, but in general the contribution of mineral dust to Na dry deposition is small (∼1%) relative to that from sea salt. In fall and winter, ∼10 to 20% of the aerosol Al, a commonly used indicator of mineral dust, is attributable to recycled sea salt, but the dust fluxes then are small, and longer‐term averages show a recycling effect of only 1 to 5% on dry deposition. The percentage of recycled Fe appears to be even less than for Al. Noncrustal/non‐sea‐salt (NC/NSS) sources account for >70% of the aerosol Sb, Se, V, and Zn, but differences in the dry deposition velocities for three particle types strongly affect their air/sea exchange. Dust can account for more than half of the new dry deposition inputs of V and Zn while the amounts of Sb and Se recycled on sea spray approach or exceed their new inputs from dust and the NSS/NC sources.
Relationship between anthropogenic CO2and the13C Suess effect in the North Atlantic Ocean
Authors: Körtzinger Arne , Quay Paul D. , Sonnerup Rolf E.
Published: May 2003

Temporal trends in oceanic dissolved inorganic carbon (DIC) and δ13C‐DIC were reconstructed along five isopycnals in the upper 1000 m of the North Atlantic Ocean using a back‐calculation approach. The mean anthropogenic DIC increase was 1.21 ± 0.07 μmol kg−1yr−1and the mean13C decrease was −0.026 ± 0.002‰ yr−1, both in good agreement with the results from previous studies. The observed δ13C‐DIC perturbation ratio is −0.024 ± 0.003‰ (μmol kg−1)−1. Our results indicate that the North Atlantic is able to maintain equilibrium with the anthropogenic perturbation for DIC and follows it with decadal time lag for δ13C. A CFC‐calibrated one‐dimensional isopycnal advection‐diffusion model is used to evaluate temporal DIC and δ13C trends and perturbation ratios of the reconstructions. We investigate the time history of the air‐sea CO2and13C disequilibria in the North Atlantic and discuss the importance of physical and biological processes in maintaining them. We find evidence that the North Atlantic Ocean is characterized by enhanced uptake of anthropogenic CO2. Also, we use the model to examine how the time rate of change of δ13C depends on changes in the temporal evolution of δ13C in the atmosphere. The model evolution explains the curious result that the time rate of change of surface water δ13C in the North Atlantic Ocean can exceed that observed concurrently in the atmosphere. Finally we introduce a powerful way of estimating the global air‐seapCO2disequilibrium based on the oceanic δ13C‐DIC perturbation ratio.
Simulating past and future dynamics of natural ecosystems in the United States
Authors: Bachelet Dominique , Neilson Ronald P. , Hickler Thomas , Drapek Raymond J. , Lenihan James M. , Sykes Martin T. , Smith Benjamin , Sitch Stephen , Thonicke Kirsten
Published: May 2003

Simulations of potential vegetation distribution, natural fire frequency, carbon pools, and fluxes are presented for two DGVMs (Dynamic Global Vegetation Models) from the second phase of the Vegetation/Ecosystem Modeling and Analysis Project. Results link vegetation dynamics to biogeochemical cycling for the conterminous United States. Two climate change scenarios were used: a moderately warm scenario from the Hadley Climate Centre and a warmer scenario from the Canadian Climate Center. Both include sulfate aerosols and assume a gradual CO2 increase. Both DGVMs simulate a reduction of southwestern desert areas, a westward expansion of eastern deciduous forests, and the expansion of forests in the western part of the Pacific Northwest and in north‐central California. Both DGVMs predict an increase in total biomass burnt in the next century, with a more pronounced increase under the Canadian scenario. Under the Hadley scenario, both DGVMs simulate increases in total carbon stocks. Under the Canadian scenario, both DGVMs simulate a decrease in live vegetation carbon. We identify similarities in model behavior due to the climate forcing and explain differences by the different structure of the models and their different sensitivity to CO2. We compare model output with data to enhance our confidence in their ability to simulate potential vegetation distribution and ecosystem processes. We compare changes in the area of drought‐induced decreases in vegetation density with a spatial index derived from the Palmer Drought Severity Index to illustrate the ability of the vegetation to cope with water limitations in the future and the role of the CO2 fertilization effect.
Coupled Al‐Si geochemistry in an ocean general circulation model: A tool for the validation of oceanic dust deposition fields?
Authors: Gehlen M. , Heinze C. , Maier‐Reimer E. , Measures C. I.
Published: May 2003

We introduced the marine cycle of Al into a geochemical ocean general circulation model in order to assess the potential of modeled surface ocean dissolved Al as a tracer for dust input to the world ocean. The geochemical cycles of Si and Al have been coupled through the dynamics of diatoms. Aluminum is added to the ocean by deposition of continental aerosols followed by partial dissolution of the aluminosilicate fraction. Dissolved Al interacts with suspended siliceous particles according to a reversible first‐order scavenging reaction. Dust fields are provided by Atmospheric General Circulation Models. A database of marine dissolved Al measurements was collated. The ocean model results for two different dust deposition fields [Andersen et al., 1998; Mahowald et al., 1999] are compared with these data. The model confirms a solubility of the aluminosilicate fraction between 1.5 and 3.0%. Modeled levels of dissolved Al in surface waters mirror the delivery of dust to the surface ocean. Comparing dissolved Al distributions resulting from the two different dust fields, yields significant differences in ocean dissolved Al distributions, which reflect a differential contribution of individual source regions. Model results suggest a significant overestimation of the North African‐Arabian desert source region for the dust field after Mahowald et al. [1999]; dust input to the central Pacific Ocean appears to be of the correct order of magnitude. This approach allows for a direct comparison of dust fields and proposes an independent check of the underlying parameterization of uplift, transport and deposition of dust.