bluuebunny/crossref_metadata_2025_split huggingface dataset:
Advances in ocean modeling for climate change research
Authors: Holland William R. , Capotondi Antonietta , Holland Marika M. 
Published: February 2004

An adequate understanding of climate variability and the eventual prediction of climate change are among the most urgent and far‐reaching efforts of the scientific community. The climate system is in an ever‐changing state with vast impact on mankind in all his activities. Both short and long‐term aspects of climate variability are of concern, and the unravelling of “natural” variability from “man‐induced” climate change is required to prepare for and ameliorate, if possible, the potentially devastating aspects of such change.In terms of scientific effort, the climate community can be thought of as the union of the disciplinary sciences of meteorology, oceanography, sea ice and glaciology, and land surface processes. Since models are based upon mathematical and numerical constructs, mathematics and computer sciences are also directly involved. In addition, some of the problems of man‐induced climate change (release of greenhouse gases, the ozone‐hole problem, etc.) are basically chemical in nature, and the expertise of the atmospheric and oceanic chemist is also required. In addition, some part of the response to climate perturbations will arise in the biological world, due to upsetting the balance in the great food web that binds communities together on both the land and the sea. Thus, the problems to be solved are extraordinarily complex and require the efforts of many kinds of scientist.
Some advances in understanding of the general circulation of the Pacific Ocean, with emphasis on recent U.S. contributions
Authors: Talley Lynne D. 
Published: February 2004

Advances in observing and understanding the general circulation of the ocean have been made continuously through the past two centuries. A recent burst of activity in the Pacific has been due to an interest and ability to understand and model the El Niño phenomenon, primarily through the Tropical Ocean Global Atmosphere (TOGA) program, and due to the interest in larger scale phenomena such as heat transport and basics of the general circulation, through activities of the World Ocean Circulation Experiment (WOCE). These experiments have built on the extensive knowledge of the Pacific Ocean derived over the previous decades; a perusal of knowledge at this point shows it to be incomplete in both observations and theory and it is hoped that the greatly increased focus on climate issues, which very much include the ocean's general circulation and its variability, will go far to improve our understanding.There have been equal or possibly greater advances in understanding the circulation of the Atlantic, and the observational base arid theory of the circulation of the Indian and Arctic Oceans have been advanced substantially. Two other reports in this volume [Fine, 1995; Hogg and Johns, 1995] survey general‐circulation related issues in the Atlantic. A review of Indian Ocean circulation at this time would be premature given the expansion of WOCE programs to the Indian Ocean in the next year. Thus in order to limit the scope of this review, the principal focus is the Pacific Ocean, emphasizing the intermediate and deep circulation and long time scales of variability. Observations are reviewed as they relate to simple theories of the circulation.
Advances in ionospheric physics: Roles, relevance and predictions in the system of solar‐terrestrial plasmas
Authors: Szuszczewicz Edward P. 
Published: February 2004

The ionosphere can be viewed as the culmination of all coupling processes in the system of solar‐terrestrial plasmas, including such diverse phenomena as coronal mass ejections, magnetospherically‐imposed electric fields, and solar‐driven thermospheric tides. It follows therefore that the accurate and self‐consistent specification of ionospheric plasma distributions represents a critical test of our understanding of the ionosphere itself and the myriad of controls and coupling mechanisms from the Sun to the Earth.There is, however, neither a code nor a model that can accurately specify the quiet‐ or storm‐time characteristics of ionospheric plasma distributions. Nor is there an adequate database to constrain the models and enforce unique quantitative solutions. Among the challenges are the ionospheric structures themselves which span eight orders of magnitude in size. Their theoretical and experimental investigation requires a broad computational grid and unique combinations of “in situ” and remote sensing techniques to define the hierarchy of sizes and cause‐effect terms. These structures range from tens‐of‐thousands of kilometers to tens‐of‐centimeters, with scale lengths that can be horizontal or vertical in the Earth's gravitational field, or parallel or perpendicular to the geomagnetic field depending on the causal mechanisms.
Toxic red tides and harmful algal blooms: A practical challenge in coastal oceanography
Authors: Anderson Donald M. 
Published: February 2004

The debate over the relative value of practical or applied versus fundamental research has heated up considerably in recent years, and oceanography has not been spared this re‐evaluation of science funding policy. Some federal agencies with marine interests have always focused their resources on practical problems, but those with a traditional commitment to basic research such as the National Science Foundation have increasingly had to fight to maintain their freedom to fund quality science without regard to practical or commercial applications.Within this context, it is instructive to highlight the extent to which certain scientific programs can satisfy both sides of this policy dilemma—i.e. address important societal issues through advances in fundamental or basic research. One clear oceanographic example of such a program involves the phenomena called “red tides” or “harmful algal blooms”. This paper describes the nature and extent of the problems caused by these outbreaks, emphasizing the alarming expansion in their incidence and their impacts in recent years, both in the U.S. and worldwide. The objective is to highlight fundamental physical, biological, and chemical oceanographic question that must be addressed if we are to achieve the practical goal of scientifically based management of fisheries resources, public health, and ecosystem health in regions threatened by toxic and harmful algae.
Global seismic tomography of the mantle
Authors: Dziewonski Adam M. 
Published: February 2004

At the end of the previous decade, a general consensus has developed that it is feasible to map on the global scale some of the largest scale 3‐D features in the Earth's deep interior and that such mapping may have fundamental significance for our understanding of the geodynamic processes, such as the flow in the mantle. General reviews of the state‐of‐the‐art for that period can be found in Dziewonski and Woodhouse [1987], Woodhouse and Dziewonski [1989] and Romanowicz [1991].In the first four years of the 1990's, significant progress has been achieved on several fronts. One of these is introduction of the new class of data: travel times measured from the long period components of digital seismograms. These data are much more accurate than, for example, those reported by the ISC, and geophysically important patterns could be detected without inversion.
Introduction to Special Section: Global Analysis, Interpretation and Modelling—Toward the Integration of Global Biogeochemical Systems
Authors: Sahagian Dork L. , Moore Berrien 
Published: February 2004

The following special section consists of papers that were presented at the First Science Conference of the Global Analysis, Interpretation and Modelling Task Force (GAIM) that was held September 24–29, 1995, in Garmisch‐Partenkirchen, Germany. The goal of GAIM is to advance the study of the coupled dynamics of the Earth system using as tools both data and models. The goal of the science conference was to provide a venue for the dissemination of scientific findings that would be steps toward developing prognostic biogeochemical models which could, in time, be coupled to models of the physical climate system.The science conference focused on papers in the areas of global data analysis and assessment, modeling of biogeochemical systems and their relationship to physical climate and hydrologic systems, and interpretation of current trends as indicated by global databases and model results for extrapolation with regard to future global change. Oral and poster session topics were grouped by time periods, including “Paleo” (<20 kyr), “Historical” (<2 kyr), “Contemporary” (<20 years), and “Future,” with an additional session concerned with global systems integration. The new and continued research directions stemming from these contributions should eventually lead to answers regarding the measurement, causes, and consequences of natural and anthropogenic global change.
Kerr microscopy of small synthetic Ti‐rich titanomagnetite grains
Authors: Ambatiello Alex , Soffel Heinrich C. 
Published: February 2004

Magnetic domain structure observations have been carried out on small synthetic Ti‐rich titanomagnetite (TM) grains (ulvöspinel content 50%–70%) employing the magneto‐optical Kerr effect (MOKE). On randomly oriented grains simple domain structures with planar domains or complex domain structures with curved domains and reverse spike domains have been observed. In addition to the description of the domain pattern, a qualitative determination of the magnetization direction within the domains is presented. Planes with a magnetization parallel to the surface show broad domains with nearly straight domain walls while planes with a magnetization normal to the surface show narrow domains and more complex patterns. With the help of the observed domain patterns on the randomly oriented grains and the knowledge about the magnetization direction within the domains a three‐dimensional (3‐D) domain structure model for Ti‐rich TM is proposed. These Ti‐rich titanomagnetites have only one easy direction of the magnetization and show a real unaxial character, although the magnetic mineral is cubic.By analysing the domain structure of more than a hundred TM particles in a range of size between 1.7 and 20 microns the transition from the single‐domain (SD) to the multidomain (MD) state is determined. The fit of the data in this study gives a critical SD size of ≈ 1.1 µm for Ti‐rich TM.
A statistical study of intense low‐altitude electric fields observed by Freja
Authors: Karlsson T. , Marklund G. T. 
Published: February 2004

Extremely intense (up to 2 V/m) and fine‐structured (1–5 km) electric fields have been observed by the Freja satellite at altitudes of 1400–1770 km. To study the occurrence and characteristics of these intense electric field events, a database was set up by searching 7 months' worth of Freja data for events with peak values greater than 200 mV/m. The intense electric field events are distributed over all local times, but they are mostly concentrated to the midnight and early morning sector of the auroral oval. The events are seen to be associated with low ambient ionospheric conductivities, but are not activity dependent. The most intense events (located in the midnight sector) are associated with the smallest scale sizes, whereas the less intense events on the day side have larger scale sizes.The findings are consistent with the interpretation that a majority of the intense electric field events observed by Freja are associated with the small‐scale, east‐west‐aligned, low‐conductivity bands devoid of auroral emissions, known as black auroral bands, or with the curls that may develop when these bands go unstable. Several observations of diverging electric fields of around 1 V/m at 800 km altitude, within the southern auroral oval, may serve as support for the prediction that intense electric fields should exist also at ionospheric altitudes.
Reply to “Inaccuracies in seismicity and magnitude data used by Varotsos and Co‐workers,” by M. Wyss
Authors: Varotsos P. , Eftaxias K. , Lazaridou M. , Dologlou E. , Hadjicontis V. 
Published: February 2004

A direct comparison of the predicted magnitude values (Mpred) to the actual magnitude values (MEQ) of the earthquakes (EQs) is allowed only when both values, i.e., Mpred and MEQ, refer to the same scale. In view of the fact that the Seismological Institute of the National Observatory of Athens (SI‐NOA) publicly announces as MEQ the ML+0.5 value (where ML the local magnitude), VAN made it clear long ago, that the predicted values Mpred (after a proper calibration) referred to ML+0.5. Therefore, a self‐consistent evaluation of VAN‐predictions should consist of a direct comparison of Mpred with the actual ML+0.5. Unfortunately, Wyss [1996] confuses the discussion by proceeding to a direct comparison of Mpred with Ms(PDE); this is not allowed because the values of ML+0.5 exceed, on the average, Ms(PDE) by 1.0 unit. An additional confusion arises from the fact that the relation suggested by Hamada [1993], i.e., ML+0.5=mb+0.3, is misinterpreted by Wyss as saying Ms(PDE)=mb+0.3. These two alterations by Wyss reveal that his Figures 1 and 2 are erroneous.Wyss [1996] also criticizes VAN, because (in an early publication) Varotsos et al. [1981b] used the Preliminary Bulletin of SI‐NOA, instead of the final one. First of all, the final bulletin could not be used by VAN at that time, because it appeared (more than one year) after the publication of the paper by Varotsos et al. [1981b]. Secondly, the correlation between SESs and EQs is evident, when we use consistently, either the preliminary, or the final bulletin of SI‐NOA. On the other hand, Wyss [1996] claims that he could not find any correlation between EQs and SESs; we show that this is due to the fact that Wyss included, in his study, small EQs that occurred several hundreds km away from the measuring VAN station (i.e., in Albania, western Turkey, etc.), but he simultaneously deleted the small magnitude EQs that occurred very close to that station. Wyss's procedure is, of course, not acceptable and hence his Appendix B is wrong. Furthermore, Wyss's claim that VAN added 25% of events to the list, is shown to be untrue.Beyond the unusual fact that Wyss quotes “VAN's statements” that have never been published by VAN, the following is also noted: although Wyss [1996] uses quotation marks (in order to indicate that he reproduced exactly what VAN said), he adds critical wording to VAN statements and hence their true meaning is drastically changed. For example, Wyss states: “Varotsos et al. [1981a] had first formulated that SESs “occurred a few minutes before each earthquake [related to that SES]” (Varotsos et al. [1981a]).” Thus, Wyss leads the reader to the wrong conclusion that VAN initially claimed that SES have a lead time of a few minutes, and that VAN changed it later. However, we show that this lead time (published by VAN) referred to another type of precursor, and not to SES, but the words in brackets (which are added by Wyss) alter the true meaning of our statement.
Carbon‐13 variations in the dissolved inorganic carbon in estuarine waters
Authors: Sackett William M. , Netratanawong Toedsit , Holmes M. Elizabeth 
Published: February 2004

The stable carbon isotope composition of dissolved inorganic carbon [DIC] was measured in Tampa Bay and Florida Bay. The dependence of isotopic composition was evaluated in terms of atmospheric CO2 exchange, carbon exchange between fresh water and seawater (i.e. salinity) and DIC derived from the reaction between calcium carbonate and organically derived CO2.The extent of organic carbon oxidation and the magnitude of organic carbon loading [pollution] in an estuary have implications for variations in the δ13C of DIC and its use as an indicator of the relative amounts of land and marine derived organic and inorganic carbon in paleogeographic studies.
Dependence of self diffusivity on P and T in molten NaAlSi2O6: Comparison of laboratory and molecular dynamics experiments
Authors: Bryce Julia G. , Spera Frank J. , Stein Daniel J. 
Published: February 2004

We have used molecular dynamics (MD) simulation to investigate ionic self‐diffusivity in NaAlSi2O6 melts and glasses at pressures of 3–58 GPa and temperatures of 2500–5000 K, to evaluate the effectiveness of a two‐body potential in reproducing pressure and temperature dependence of tracer self‐diffusivities. For each species, self‐diffusivity increased with increasing temperature; with increasing pressure up to ∼15 GPa, the self‐diffusivity of O, Si, and Al increased, while mobility of Na decreased. An Arrhenian fit to self‐diffusivity data collected from simulations at temperatures above the kinetic glass transition (up to 15 GPa) gives: Species	Ea	Va	log D*	(kJ/mol)	(×106m³/mol)	(m²/s) Na	81±14	3.5±0.5	−6.8±0.17 Al	306±31	−5.6±1.1	−6.5±0.35 Si	294±23	−6.1±0.9	−6.9±0.26 O	302±23	−5.9±0.8	−6.6±0.26 for activation energy (Ea) and activation volume (Va). The MD‐derived Ea,o and Va,o agree with laboratory results of 275±10 kJ/mol and −6.2±0.6 cm³/mol for Ea,o and Va,o respectively [Shimizu and Kushiro, 1984] measured in experiments at 1673 to 1923 K and 0.5 to 2 GPa. Agreement with the pre‐exponential factor (D*) is poorer, with MD result of ∼10−6.6 for O and laboratory value ∼10−4.7. From ∼15 GPa–25 GPa, Va is ∼0 m³/mol for O, Si, and Al; these species have a positive Va for pressures above 25 GPa (Va,o is ∼ +1 cm³/mol). For pressures ∼15 GPa the majority of the network cations are in 5‐ or 6‐ fold coordination, and more than 20% of the O is in 3‐fold coordination. With increasing pressure, 4‐fold Si and Al decrease monotonically, while 6‐fold Si and Al increase monotonically. Pentahedral Si and Al maximize at nearly the same pressure as O self‐diffusivity.
A 50–70 year climatic oscillation over the North Pacific and North America
Authors: Minobe Shoshiro 
Published: February 2004

The chronology of interdecadal climatic regime shifts is examined, using instrumental data over the North Pacific, North America and the tropical oceans, and reconstructed climate records for North America. In the North Pacific and North America, climatic regime shifts around 1890 and in the 1920s with alternating polarities are detected, whose spatial structure is similar to that of the previously‐known climatic shifts observed in the 1940s and 1970s. Sea‐surface temperatures in the tropical Indian Ocean‐maritime continent region exhibit changes corresponding to these four shifts. Spectra obtained by the Multi‐Taper‐Method suggest that these regime shifts are associated with 50–70 year climate variability over the North Pacific and North America.The leading mode of the empirical orthogonal functions of the air‐temperature reconstructed from tree‐rings in North America exhibits a spatial distribution that is reminiscent of instrumentally observed air‐temperature differences associated with the regime shifts. The temporal evolution of this mode is characterized by a 50–70 year oscillation in the eighteenth and nineteenth centuries. This result, combined with the results of the analyses of the instrumental data, indicates that the 50–70 year oscillation is prevalent from the eighteenth century to the present in North America.
Ice‐age cycles: Earth's rotation instabilities and sea‐level changes
Authors: Sabadini R. , Vermeersen L. L. A. 
Published: February 2004

A new class of multilayered, viscoelastic Earth models based on PREM is applied to the modeling of Earth's rotation instabilities and associated sea‐level changes, induced by the occurrence of Pleistocene ice‐age cycles that match the oxygen isotope records over the last 0.8 Myr. The novelty of our approach stands on the usage, for the first time in post‐glacial rebound induced sea‐level studies, of a fully analytical scheme based on normal mode theory that allows to deal with complexities of the real Earth, such as lithospheric and mantle layering, sphericity and self‐gravitation. The ice models are based on ICE‐3G.Our results show that differences in true polar wander (TPW) and TPW‐induced sea‐level changes between Earth models with a few layers and models having enough layers so that saturated continuum limits are reached, can amount factors 2 to 3. This may change conclusions derived from some earlier studies on polar wander induced changes in climate, that were based on Earth models with a limited amount of layers. The results indicate that models containing about 15 layers with a stratified lower mantle and transition zone have reached saturated continuum responses for both TPW and TPW‐induced sea‐level changes. Stratification of the lithosphere is not important. This is in contrast with the sensitivity of post‐seismic deformation models. This difference in sensitivity on the radial profile of the Earth model can be explained with simple arguments on the dependence on zonal degree.
Effects of instability waves in the mixed layer of the equatorial Pacific
Authors: Baturin N. G. , Niiler P. P. 
Published: February 2004

Data from more than 1900 Lagrangian drifters in the equatorial Pacific Ocean from 1980 to 1994 together with velocity records from two Tropical Ocean‐Global Atmosphere ‐ Tropical Atmosphere Ocean (TOGA‐TAO) equatorial moorings at 11° and 140°W, advanced very high resolution radiometer (AVHRR) sea surface temperature (SST) product, and European Centre for Medium‐Range Weather Forecasts (ECMWF) winds were used to investigate the effects and energetics of currents associated with the tropical instability waves (TIWs). Adaptive multitaper spectral analysis was used to estimate how spectral energy varied in the 15‐to‐30‐day period TIW band. The drifter data was analyzed separately for high and low values of the TIW energy in regions of 20° longitude by 20° latitude centered at 0°N, 110°W and 0°N, 140°W to construct meridional profiles of energetics of the TIW region. High TIW energy values typically occurred around October when the South Equatorial Current (SEC) and the North Equatorial Countercurrent (NECC) both became stronger and the eddy kinetic and potential energy production at 140°W was noticeably larger. At 110°W the eddy kinetic and potential energy production existed all the time without large differences between the periods of high and low TIW activity. The meridional kinetic energy was enhanced in the region between the equator and 10°N from 150° to 100°W, with the largest values occurring between 110° and 140°W in longitude and around 5°N in latitude. The largest terms in the horizontal kinetic energy production equation were
and
with maxima in the region of anticyclonic shear between SEC and NECC, from 2° to 6°N. The temperature variance, or the potential energy production, peaked closer to the equator at 3°N. The linear growth timescale of the instability was about 10 days.The time‐variable wind supplied energy to the current fluctuations during the TIW off period, but for the TIW on period the wind energy input was reduced (at 110W) or even reversed (at 140°W, between 1°S and 7°N), suggesting that air‐sea interaction was important in the total energy balance of the waves. The effect of instability was to reduce the shear of the mean current and to warm the equatorial cold tongue. These calculations suggest that there exists a balance between energy production and dissipation in the TIWs.