bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular genetic characterization of the Fennoscandian cervid strain, a new genotypic group (G10) ofEchinococcus granulosus
Authors: LAVIKAINEN A. , LEHTINEN M. J. , MERI T. , HIRVELÄ-KOSKI V. , MERI S.
Published: August 2003

The northern biotype ofEchinococcus granulosusoccurs in North America and northern Eurasia in life-cycles involving cervids. Previously, cervid isolates ofE. granulosusfrom North America have been characterized using molecular genetic techniques as the G8 genotype. In this study, 5 isolates ofE. granulosuswere collected from 4 reindeer and 1 moose in north-eastern Finland. DNA sequences within regions of mitochondrial cytochromecoxidase I (COI) and NADH dehydrogenase I (NDI) genes and the internal transcribed spacer 1 (ITS-1) fragment of the ribosomal DNA were analysed. The mitochondrial nucleotide sequences were identical in all isolates, but high sequence variation was found in the ITS-1 region. Mitochondrial and nuclear sequences of the Finnish cervidE. granulosusand the camel strain (G6) ofE. granulosusresembled closely each other. According to phylogenetic analyses, the Finnish isolates have close relationships also with the pig (G7) and cattle (G5) strains. Although some similarities were found with the previously published North American cervid strain (G8), particularly in the NDI sequence and some of the ITS-1 clones, the FinnishE. granulosusform represents a distinct, previously undescribed genotype ofE. granulosus. The novel genotype is hereby named as the Fennoscandian cervid strain (G10).
A Life Less Ordinary: the Ritualization of the Domestic Sphere in Later Prehistoric Europe
Authors: Bradley Richard
Published: August 2003

This article, which is based on the fourteenth McDonald Lecture, considers two tensions in contemporary archaeology. One is between interpretations of specific structures, monuments and deposits as the result of either ‘ritual’ or ‘practical’ activities in the past, and the other is between an archaeology that focuses on subsistence and adaptation and one that emphasizes cognition, meaning, and agency. It suggests that these tensions arise from an inadequate conception of ritual itself. Drawing on recent studies of ritualization, it suggests that it might be more helpful to consider how aspects of domestic life took on special qualities in later prehistoric Europe. The discussion is based mainly on Neolithic enclosures and other monuments, Bronze Age and Iron Age settlement sites and the Viereckschanzen of central Europe. It may have implications for field archaeology as well as social archaeology, and also for those who study the formation of the archaeological record.
From Inscribed Bodies to Distributed Persons: Contextualizing Tairona Figural Images in Performance
Authors: Looper Matthew G.
Published: August 2003

Following trends in anthropology, the human body has recently become an important topic of discourse in archaeology. While some anthropologists consider the body as a social metaphor or site of symbolic inscription, others have questioned the validity of approaches based on the dichotomization and hierarchization of the mind and body. Semasiology, in particular, offers an epistemologically sound basis for interpreting the body, by grounding agency in the socially-structured actions that constitute corporeal space. This article applies the semasiological concept of the action-sign to archaeological problems through an examination of the interrelationship between Tairona anthropomorphic imagery and remains of ceremonial architecture at Pueblito, an archaeological site in Colombia. In both cases, physical remains constitute the traces of the actions through which agential persons created sacred spaces, and the meanings of these spaces may be more fully reconstructed by comparing diverse modes of embodiment. Tairona figural art and architecture constitute a creative technology, serving as an indexically-bound nexus of embodied social action.
Seafaring in the Pleistocene
Authors: Bednarik Robert G.
Published: August 2003

Archaeological data from Wallacea (Indonesia) and elsewhere are summarized to show that the history of seafaring begins in the Early Pleistocene, and that this human capability eventually led to Middle Palaeolithic ocean crossings in the general region of Australia. To understand better the technological magnitude of these many maritime accomplishments, a series of replicative experiments are described, and the theoretical conditions of these experiments are examined. The proposition is advanced that hominid cognitive and cultural evolution during the Middle and early Late Pleistocene have been severely misjudged. The navigational feats of Pleistocene seafarers confirm the cultural evidence of sophistication available from the study of palaeoart.

With comments from Mike Morwood, Michael Rowland, Matthew Spriggs, Iain Davidson, Ursula Mania, and G.A. Clark and followed by a reply from the author.
Pleistocene Exchange Networks as Evidence for the Evolution of Language
Authors: Marwick Ben
Published: August 2003

Distances of raw material transportation reflect how hominid groups gather and exchange information. Early hominids moved raw materials short distances, suggesting a home range size, social complexity and communication system similar to primates in equivalent environments. After about 1.0 million years ago there was a large increase in raw material transfer distances, possibly a result of the emergence of the ability to pool information by using a protolanguage. Another increase in raw material transfer occurred during the late Middle Stone Age in Africa (after about 130,000 years ago), suggesting the operation of exchange networks. Exchange networks require a communication system with syntax, the use of symbols in social contexts and the ability to express displacement, which are the features of human language. Taking the Neanderthals as a case study, biological evidence and the results of computer simulations of the evolution of language, I argue for a gradual rather than catastrophic emergence of language coinciding with the first evidence of exchange networks.
PPNA Jericho: a Socio-political Perspective
Authors: Naveh Danny
Published: August 2003

A reexamination of the published data concerning PPNA Jericho is used to demonstrate that various building operations, especially the monumental buildings, were actively functioning in several social spheres, both at the inter-group and intra-group levels. At the inter-group level, the monumental buildings served as a means to establish a hold over an area with favourable resources. At the intra-group level, they functioned in founding and regulating new types of socioeconomic relations. Central themes in the changes occurring at this level include production intensification and the growing prominence of long-term delayed-return obligations within the socioeconomic system
Seeing the ‘Unseen’: Fragmented Cues and the Implicit in Palaeolithic Art
Authors: Hodgson Derek
Published: August 2003

Palaeolithic Art is generally thought to be based primarily upon the explicit conscious aspects of recognition and memory. Recent research into perception and cognition, however, has revealed a ‘hidden’ substructure of processing, known as implicit perception and memory, that functions in a different way to overt modes of cognisance but, yet, by dovetailing with consciously defined determinants helps to define how these are structured. As the making of Palaeolithic Art would have been contingent on the perceptual/recognition/visual memory system, it is therefore admirably suited to an understanding from the standpoint of implicit processes. Here I will demonstrate how the enduring features of this art can be investigated from the perspective of implicit, or covert, psychological factors and the consequences of this approach for the genesis of this art.
The Fragility of Imperialist Ideology and the End of Local Traditions, an Inca Example
Authors: Jennings Justin
Published: August 2003

Imperial expansions tend to be legitimated by myths of empire that support the position of a particular group of ruling élite. In order to maintain their power, these élites must take this ideology seriously or risk losing their positions to those that will. In the Inca Empire of the Andes, expansion was justified in large part as a divine mandate to spread a true religion to the people. Although the Inca generally strove to maintain local religions, a long-standing ritual tradition involving painted tablets ended with the Inca conquest of southern Peru. The demise of this practice suggests a greater imperial concern for providing proper gifts to the gods than can be gleaned from the historical records.
A multiprocessor coupled ice‐ocean model for the Baltic Sea: Application to salt inflow
Authors: Meier H. E. Markus , Döscher Ralf , Faxén Torgny
Published: August 2003

Within the Swedish Regional Climate Modeling Program, SWECLIM, a three‐dimensional (3‐D) coupled ice‐ocean model for the Baltic Sea has been developed to simulate physical processes on timescales of hours to decades. The code has been developed based on the massively parallel version of the Ocean Circulation Climate Advanced Modeling (OCCAM) project of the Bryan‐Cox‐Semtner model. An elastic‐viscous‐plastic ice rheology is employed, resulting in a fully explicit numerical scheme that improves computational efficiency. An improved two‐equation turbulence model has been embedded to simulate the seasonal cycle of surface mixed layer depths as well as deepwater mixing on decadal timescale. The model has open boundaries in the northern Kattegat and is forced with realistic atmospheric fields and river runoff. Optimized computational performance and advanced algorithms to calculate processor maps make the code fast and suitable for multi‐year, high‐resolution simulations. As test cases, the major salt water inflow event in January 1993 and the stagnation period 1980–1992, have been selected. The agreement between model results and observations is regarded as good. Especially, the time evolution of the halocline in the Baltic proper is realistically simulated also for the longer period without flux correction, data assimilation, or reinitialization. However, in particular, smaller salt water inflows into the Bornholm Basin are underestimated, independent of the horizontal model resolution used. It is suggested that the mixing parameterization still needs improvements. In addition, a series of process studies of the inflow period 1992/1993 have been performed to show the impact of river runoff, wind speed, and sea level in Kattegat. Natural interannual runoff variations control salt water inflows into the Bornholm Basin effectively. The effect of wind speed variation on the salt water flux from the Arkona Basin to the Bornholm Basin is minor.
Modeling the formation and circulation processes of water masses and sea ice in the Gulf of St. Lawrence, Canada
Authors: Saucier François J. , Roy François , Gilbert Denis , Pellerin Pierre , Ritchie Harold
Published: August 2003

The seasonal cycle of water masses and sea ice in the Gulf of St. Lawrence is examined using a three‐dimensional coastal ice‐ocean model with realistic tidal, atmospheric, hydrologic, and oceanic forcing. The model includes a level 2.5 turbulent kinetic energy equation. A model simulation over 1997–1998 is verified against available data on sea ice, temperature, and salinity. The results demonstrate a consistent seasonal cycle in atmosphere‐ocean exchanges and the formation and circulation of water masses and sea ice. The accuracy of radiative, momentum, and sensible heat exchanges at the sea surface, and the production of turbulent kinetic energy from winds and tides, are critical to the accuracy of the modeled circulation. The analysis of the mean error on near‐surface temperature and salinity in the late summer and fall using standard bulk exchange coefficients and radiation (about 1°C too cold and 1 salinity unit too fresh) shows the tradeoff between tidal mixing at the head of the Laurentian Channel, and wind‐driven circulation and mixing in the surface waters. The results suggest year‐long stratification in the estuary and northwestern Gulf, with little mixing except near the head region, where relatively deep warmer waters are mixed to the surface during winter, and cold intermediate waters are efficiently withdrawn during summer. The results suggest that the summer cold waters found at intermediate depths in the estuary and northwestern Gulf are not formed in situ. A significant fraction of these waters enters through the Strait of Belle Isle in wintertime, eventually reaching the estuary within about 6 months.
Characterization of the mean and seasonal flow regime on Georges Bank from shipboard acoustic Doppler current profiler data
Authors: Flagg Charles N. , Dunn Maureen
Published: August 2003

From 1995 through 1999 the Northwest Atlantic GLOBEC program sponsored over 100 oceanographic cruises to Georges Bank and the surrounding waters. About 12,000 hours of shipboard acoustic Doppler current profiler (ADCP) data were collected during the program on more than 80 of these cruises, forming one of the most extensive three‐dimensional current measurement data sets ever collected. These data have been used here to examine the seasonal variability of the bank’s barotropic flow field. The variability has been described using the 5 years of ADCP observations to derive both small area statistics and seasonal least squares fits, and a more flexible description based upon interpolating functions describing the spatial and temporal dependence of the bank‐wide stream functions. Both methods show the seasonal acceleration of the bank gyre in the summer with larger velocities along the north flank and smaller seasonal variations over the southern flank. The stream functions show the seasonal change from a winter condition with on‐bank flow from the northwest through to the acceleration and ecologically critical closure of the anticyclonic Georges Bank gyre during the summer. On the basis of annual and semiannual decompositions of the seasonal progression, the closure of the gyre in the area of the Great South Channel appears to occur by June, first in the shallow waters and then progressively southward, but it does not extend as far as the middle of the southern flank. A series of monthly Lagrangian drift predictions based upon the stream function analysis, suggest that the observed seasonal movement of the larval fish from their spawning grounds over the Northeast Peak in March, through to their late summer concentration over the central bank, can generally be ascribed to the seasonal barotropic flow over the inner portion of the bank. The analysis also showed that those larvae found over the outer part of the bank are, almost certainly, doomed to be swept out of the banks’ ecosystem, to either the west or south.
A theoretical analysis of sliding of rough surfaces
Authors: Walsh J. B.
Published: August 2003

I used a model proposed by Greenwood and Williamson [1966], who analyzed closure between a rough surface and a smooth surface under normal stress, to analyze the growth of slip under increasing shear stress, normal stress remaining constant. The two bodies are elastic half‐spaces, one rough and one smooth, and Coulomb friction resists slip at sliding contacts. The elastic and dissipative components of the constitutive relation in shear depend upon statistical parameters which describe the topography of the rough surface. I made a parametric study of the effect of topography on the constitutive relations in shear by comparing a model in which the progress of slip at a contact is continuous with one in which the contact goes discontinuously from “stuck” to sliding. The effect of topography was also studied by assuming that the probability density distribution of the heights of asperities is Gaussian or, alternatively, a negative exponential. These variations in topography produced only minor differences in the constitutive behavior. This insensitivity of the constitutive behavior to differences in the statistical description of the topography arises in part because, only relatively, a small range of asperity heights is active in typical experiments. Work done against friction introduces a dissipative component into the constitutive behavior which I evaluated analytically; I show that the components have a simple graphical construction on plots of shear stress versus displacement developed from experimental observations. Sliding in the reverse sense which occurs when the applied shear stress is relaxed is analyzed, resulting in expressions which describe the shape of hysteresis loops formed when shear stress is cycled. Introducing measurements made on surfaces of specimens of granite and quartzite into the theoretical relations, I found reasonable agreement with experimental data.
Rheology of the lithosphere inferred from postseismic uplift following the 1959 Hebgen Lake earthquake
Authors: Nishimura Takuya , Thatcher Wayne
Published: August 2003

We have modeled the broad postseismic uplift measured by geodetic leveling in the epicentral area of the 1959 Mw = 7.3 Hebgen Lake, Montana earthquake, a normal faulting event in the northern Basin and Range province. To fit the observed uplift we calculate synthetic postseismic deformation using the relaxation response of a gravitational viscoelastic Earth to the earthquake. For a model with an elastic plate overlying a viscoelastic half‐space, we find that the elastic thickness is 38 ± 8 km, which is close to the local crustal thickness. The half‐space viscosity is estimated at 4 × 1018±0.5 Pa s. The leveling data do not require a viscous lower crust but permit a lower bound viscosity of 1020 Pa s. The observed broad uplift cannot be explained by physically plausible afterslip on and below the coseismic fault. However, local deformation across the coseismic surface rupture requires shallow afterslip reaching the surface. The postseismic deformation induced by the estimated viscoelastic structure decays exponentially with a time constant of ∼15 years. Because of coupling between the elastic layer and the viscoelastic substrate, this relaxation time is significantly longer than the 2 year Maxwell relaxation time of the viscous half‐space itself. Our result suggests the importance of postseismic relaxation in interpreting high‐precision global positioning system velocities. For example, our model results suggest that postseismic transient velocities from both the 1959 Hebgen Lake and the 1983 Mw = 6.9 Borah Peak earthquakes are currently as large as 1–2 mm/yr.
Monitoring landslide displacements by using ground‐based synthetic aperture radar interferometry: Application to the Ruinon landslide in the Italian Alps
Authors: Tarchi Dario , Casagli Nicola , Moretti Sandro , Leva Davide , Sieber Alois J.
Published: August 2003

Synthetic aperture radar (SAR) data are collected by a ground‐based radar system forming the synthetic aperture by the sliding of the antennas on a linear rail. Coherent SAR processing converts the raw data into a complex image. The phase of each image pixel contains information on the target‐sensor distance and can be exploited as a ranging tool. The interferometric technique, based on the comparison between paired and coherent SAR images taken at different times, permits the quantitative extraction of this information, thus allowing the monitoring of the morphological changes. The portable device used in this application was developed by the Joint Research Center, Ispra, Italy, specifically for measurements in the field. It is known as Linear SAR, and it is able to provide 17 GHz measurements with a 2.8 m synthetic aperture. A measurement campaign, lasting about 1 week, was performed between July and August 2000 for monitoring superficial displacements at the Ruinon landslide, a 30 million m3 rockslide in the Italian Alps. Two sequences of interferograms are presented and discussed. The interpretation of the sequences has allowed us to derive multitemporal deformation maps of the test area, thus showing the entire displacement field of those landslide sectors characterized by higher radar reflectivity and coherence. Displacement rates up to 1.2 mm h−1 have been measured with a pixel resolution of 5 m and a measurement precision of 0.75 mm. The results have been validated by using ground truth data obtained through automatic extensometers and topographic measurements. Discrepancies are limited to a few millimeters.
A mechanism for sustained groundwater pressure changes induced by distant earthquakes
Authors: Brodsky Emily E. , Roeloffs Evelyn , Woodcock Douglas , Gall Ivan , Manga Michael
Published: August 2003

Large, sustained well water level changes (>10 cm) in response to distant (more than hundreds of kilometers) earthquakes have proven enigmatic for over 30 years. Here we use high sampling rates at a well near Grants Pass, Oregon, to perform the first simultaneous analysis of both the dynamic response of water level and sustained changes, or steps. We observe a factor of 40 increase in the ratio of water level amplitude to seismic wave ground velocity during a sudden coseismic step. On the basis of this observation we propose a new model for coseismic pore pressure steps in which a temporary barrier deposited by groundwater flow is entrained and removed by the more rapid flow induced by the seismic waves. In hydrothermal areas, this mechanism could lead to 4 × 10−2 MPa pressure changes and triggered seismicity.
Three‐dimensional effects in shear waves
Authors: Zhao Qun , Svendsen I. A. , Haas Kevin
Published: August 2003

Most studies on shear waves to date have assumed the flow is depth uniform (two dimensional). In the present study, we utilize the quasi‐three‐dimensional (quasi‐3D) nearshore circulation model SHORECIRC to study shear waves. Our results show that shear wave flow is more organized in the quasi‐3D simulation than in the 2D simulation. In the 2D simulation, the vortices are moving farther offshore of the bar, while in the quasi‐3D simulation, they are more confined to the shoreward side of the bar. Moreover, the shear waves in the quasi‐3D simulation are much less energetic than in the 2D simulation, though the total momentum mixing for the two cases is not significantly different. To understand which mechanisms cause the differences in the 2D and the quasi‐3D simulation, the momentum, kinetic energy, and enstrophy equations for the mean flow and the shear waves are derived. The momentum, energy, and enstrophy balances are discussed using the numerical results from the idealized SUPERDUCK topography and the wave conditions on October 16, 1986. The effects of the quasi‐3D dispersion due to the depth varying currents on shear waves are illustrated. Analysis of the mean momentum balance shows that both the shear waves and the quasi‐3D current pattern contribute to the momentum transfer, and the momentum transfer provided by the shear waves is sometimes larger than that by the quasi‐3D dispersive terms. The kinetic energy balance of the shear waves shows that the quasi‐3D dispersive terms will extract kinetic energy from the depth‐averaged shear waves. Furthermore, the enstrophy equation demonstrates that the quasi‐3D dispersion terms provide vortex tilting, which allows three‐dimensional vortex interactions.
Generation and unstable evolution of a density‐driven Eastern Poleward Current: The Iberian Poleward Current
Authors: Peliz Álvaro , Dubert Jesus , Haidvogel Dale B. , Le Cann Bernard
Published: August 2003

The generation and evolution of a density‐driven Eastern Poleward Current is investigated using a high‐resolution primitive equation numerical model. The simulations focus on the Iberian Poleward Current (IPC) as a case study. The flow is generated by a meridional upper ocean density gradient balanced by an eastward surface‐intensified flow that adjusts at the coastal margin. The resulting current system has a baroclinic character with poleward flow at the surface layer, and equatorward flow underneath. A few weeks after initialization, the sheared along‐slope flow generates several vorticity structures downstream of the main topographic features. In the lee of the topography, persistent anticyclones are observed and deep cyclogenesis is induced in relation to the meandering of the upper layer jet. These structures evolve preferentially as cyclone/anticyclone eddy pairs, and after interaction some dipoles are ejected offslope. Within a period of a few months, the initial meridional gradient evolves into a complex system of fronts, eddies and slope flows. The dynamics of flow topography interaction is analyzed. A comparison with satellite imagery of the IPC is conducted and similarity in scales and patterns is noted.
Detection of large‐scale climate signals in spring vegetation index (normalized difference vegetation index) over the Northern Hemisphere
Authors: Gong Dao‐Yi , Ho Chang‐Hoi
Published: August 2003

Climate is one of the determinants driving ecosystems on both local and global scales. During the last two decades, there has occurred a dramatic temperature increase in the northern midlatitudes to high latitudes. The rapid warming has resulted in the promotion of bioactivity and an early growing season. However, the temperature and vegetation changes are not uniform in geographical distribution. In the present study, we analyze the spatial features in the normalized difference vegetation index (NDVI)‐temperature relationship over Eurasia and North America in spring for the period 1982–2000. The NDVI data are derived from the Earth Observing System Pathfinder advanced very high resolution radiometer data sets. A singular value decomposition analysis is applied to the covariance matrix of the NDVI and temperature. Most of the squared covariance, 91.6%, is captured by the first seven paired modes. The result clearly indicates that the temperature is a focal factor influencing vegetation activity. Furthermore, those seven paired modes show large‐scale features and well‐defined patterns. The atmospheric circulation systems, such as the Southern Oscillation, North Atlantic Oscillation/Arctic Oscillation, Pacific/North American pattern, Eurasian pattern, western Pacific pattern, western Atlantic pattern, eastern Atlantic pattern, and North Pacific index, are found to be associated with that. The time coefficient corresponding to the first paired modes, centered on western Siberia, is correlated significantly with the Eurasian teleconnection pattern. Their correlation coefficients are 0.72 and 0.78 for vegetation and temperature, respectively, for the data period. Other modes are also correlated with one or more circulation indices. This implies that the large‐scale circulation is essential for understanding the regional response of vegetation to global climate change. Taking all nine circulation indices and time lags into account, a large portion (71%) of the satellite‐sensed variance in NDVI could be explained. The temperature‐NDVI relationships did not change significantly when the NDVI was rescaled from 1 to 5 degrees, indicating that the singular value decomposition analysis is an appropriate technique for detecting the degree of coupling between vegetation and climate and that the vegetation‐temperature relationship presented in this study is robust.
Ozone profile retrieval from Global Ozone Monitoring Experiment (GOME) data using a neural network approach (Neural Network Ozone Retrieval System (NNORSY))
Authors: Müller M. D. , Kaifel A. K. , Weber M. , Tellmann S. , Burrows J. P. , Loyola D.
Published: August 2003

The inverse radiative transfer equation to retrieve atmospheric ozone distribution from the UV‐visible satellite spectrometer Global Ozone Monitoring Experiment (GOME) has been modeled by means of a feed forward neural network. This Neural Network Ozone Retrieval System (NNORSY) was trained exclusively on a data set of GOME radiances collocated with ozone measurements from ozonesondes, Halogen Occultation Experiment, Stratospheric Aerosol and Gas Experiment II, and Polar Ozone and Aerosol Measurement III. Network input consists of a combination of spectral, geolocation, and climatological information (time and latitude). In the stratosphere the method globally reduces standard deviation with respect to an ozone climatology by around 40%. Tropospheric ozone can also be retrieved in many cases with corresponding reduction of 10–30%. All GOME data from January 1996 to July 2001 were processed. In a number of case studies involving comparisons with ozonesondes from Hohenpeissenberg, Syowa, and results from the classical Full Retrieval Method, we found good agreement with our results. The neural network was found capable of implicitly correcting for instrument degradation, pixel cloudiness, and scan angle effects. Integrated profiles generally agree to within ±5% with the monthly Total Ozone Mapping Spectrometer version 7 total ozone field. However, some problems remain at high solar zenith angles and very low ozone values, where local deviations of 10–20% have been observed in some cases. In order to better characterize individual ozone profiles, two local error estimation methods are presented. Vertical resolution of the profiles was assessed empirically and seems to be of the order of 4–6 km. Since neural network retrieval is a mathematically simple, one‐step procedure, NNORSY is about 103–105times faster than classical retrieval techniques based upon optimal estimation.
Effects of spatial and temporal variability in soil moisture on widths and δ13C values of eastern Siberian tree rings
Authors: Kagawa A. , Naito D. , Sugimoto A. , Maximov T. C.
Published: August 2003

We studied the relationships between earlywood/latewood width, stable carbon isotope ratio (δ13C) of cellulose, and soil moisture at a dry and a wet site in Yakutsk, eastern Siberia, which differed considerably in soil water conditions. Recharge of soil water by snowmelt in spring and subsequent drought in summer provided a marked seasonal contrast in soil water conditions between the earlywood and latewood formation period. Ring index was calculated by dividing each earlywood/latewood width by the 5‐year averaged width for each individual. In order to determine whether drought influenced the ring index‐δ13C relation, the ring index time series were compared with δ13C time series. We collected wood samples from eight Larix gmelinii (Rupr.) Rupr. and four Pinus sylvestris L. trees from the two sites and measured the earlywood and latewood widths and δ13C of earlywood and latewood formed during the years 1996–2000. At the dry site, seasonal soil water content variation corresponded to seasonal δ13C variation of tree rings. We found negative ring index‐δ13C correlations in latewood for both species at the dry site mainly dominated by Pinus but not in latewood of Larix at the wet site dominated by Larix. Decrease and/or early cessation of latewood growth and increase in δ13C under drought conditions possibly explain this negative correlation. This suggests the growth limitation of trees in this region by drought and the prospects of reconstructing past drought with latewood δ13C of the dry site.
A model for the radiative forcing during ACE‐Asia derived from CIRPAS Twin Otter and R/V Ronald H. Brown data and comparison with observations
Authors: Conant William C. , Seinfeld John H. , Wang Jian , Carmichael Gregory R. , Tang Youhua , Uno Itsushi , Flatau Piotr J. , Markowicz Krzysztof M. , Quinn Patricia K.
Published: August 2003

Vertical profiles of aerosol size, composition, and hygroscopic behavior from Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) Twin Otter and National Oceanic and Atmospheric Administration R/V Ronald H. Brown observations are used to construct a generic optical model of the Asian Pacific Regional Aerosol Characterization Experiment (ACE‐Asia) aerosol. The model accounts for sulfate, black carbon, organic carbon, sea salt, and mineral dust. The effects of relative humidity and mixing assumptions (internal versus external, coating of dust by pollutants) are explicitly accounted for. The aerosol model is integrated with a Monte Carlo radiative transfer model to compute direct radiative forcing in the solar spectrum. The predicted regional average surface aerosol forcing efficiency (change in clear‐sky radiative flux per unit aerosol optical depth at 500 nm) during the ACE‐Asia intensive period is −65 Wm−2 for pure dust and −60 Wm−2 for pure pollution aerosol (clear skies). A three‐dimensional atmospheric chemical transport model (Chemical Weather Forecast System (CFORS)) is used with the radiative transfer model to derive regional radiative forcing during ACE‐Asia in clear and cloudy skies. Net regional solar direct radiative forcing during the 5–15 April 2001 dust storm period is −3 Wm−2 at the top of the atmosphere and −17 W m−2 at the surface for the region from 20°N to 50°N and 100°E to 150°E when the effects of clouds on the direct forcing are included. The model fluxes and forcing efficiencies are found to be in good agreement with surface radiometric observations made aboard the R.H. Brown. Mean cloud conditions are found to moderate the top of atmosphere (TOA) radiative forcing by a factor of ∼3 compared to clear‐sky calculations, but atmospheric absorption by aerosol is not strongly affected by clouds in this study. The regional aerosol effect at the TOA (“climate forcing”) of −3 Wm−2 is comparable in magnitude, but of opposite sign, to present‐day anthropogenic greenhouse gas forcing. The forcing observed during ACE‐Asia is similar in character to that seen during other major field experiments downwind of industrial and biomass black carbon sources (e.g., the Indian Ocean Experiment (INDOEX)), insofar as the primary effect of aerosol is to redistribute solar heating from the surface to the atmosphere.
Comparison of two fitting methods for the log‐logistic distribution
Authors: Ashkar Fahim , Mahdi Smail
Published: August 2003

We investigate generalized probability weighted moments (GPWM) and maximum likelihood (ML) fitting methods in the two‐parameter log‐logistic (LL) model. Parameter and quantiles estimators are computed along with their asymptotic variances and covariances. A comparison of these methods is done by simulation. It is concluded that for estimating β, GPWM can provide better results than the ML method. However, for estimating quantiles, GPWM provides better results only for very small sample sizes, especially when the distribution is quite asymmetrical. Although presently, LL is not one of the distributions frequently used in hydrology, we agree with some authors that it merits wider use in hydrological practice. For a clearer idea on the merits of LL, we compare it with three other distributions for fitting flood data from 114 hydrometric stations in Canada. The results support our view regarding the good fitting potential of the LL distribution to extreme hydrologic data.
Effective and efficient algorithm for multiobjective optimization of hydrologic models
Authors: Vrugt Jasper A. , Gupta Hoshin V. , Bastidas Luis A. , Bouten Willem , Sorooshian Soroosh
Published: August 2003

Practical experience with the calibration of hydrologic models suggests that any single‐objective function, no matter how carefully chosen, is often inadequate to properly measure all of the characteristics of the observed data deemed to be important. One strategy to circumvent this problem is to define several optimization criteria (objective functions) that measure different (complementary) aspects of the system behavior and to use multicriteria optimization to identify the set of nondominated, efficient, or Pareto optimal solutions. In this paper, we present an efficient and effective Markov Chain Monte Carlo sampler, entitled the Multiobjective Shuffled Complex Evolution Metropolis (MOSCEM) algorithm, which is capable of solving the multiobjective optimization problem for hydrologic models. MOSCEM is an improvement over the Shuffled Complex Evolution Metropolis (SCEM‐UA) global optimization algorithm, using the concept of Pareto dominance (rather than direct single‐objective function evaluation) to evolve the initial population of points toward a set of solutions stemming from a stable distribution (Pareto set). The efficacy of the MOSCEM‐UA algorithm is compared with the original MOCOM‐UA algorithm for three hydrologic modeling case studies of increasing complexity.
Transport behavior in three‐dimensional fracture intersections
Authors: Park Young‐Jin , Lee Kang‐Kun , Kosakowski Georg , Berkowitz Brian
Published: August 2003

Flow and transport patterns in three‐dimensional fracture intersections are investigated, with emphasis on the occurrence and effects of local flows around each intersection. Flow and transport simulations indicate that local flow circulations (referred to as “local flow cells”) arise because of an interplay between intersection geometry and corresponding boundary conditions for flow along the fracture boundaries. Local flow cells are thus unique features in three‐dimensional fracture networks. The analysis here suggests that local flow cells have little effect on the overall fluid flow in a fracture network but may constitute an effective mechanism which contributes to the long breakthrough tailing and retardation often observed in transport through discrete fracture networks.
Can continuous streamflow data support flood frequency analysis? An alternative to the partial duration series approach
Authors: Claps P. , Laio F.
Published: August 2003

Common procedures for flood frequency modeling are based on analysis of series of annual maxima (AMS) of the instantaneous discharge. A practical alternative to AMS series is usually considered when the record length is short. In this case, analysis of partial duration series (PDS) on continuous streamflow records allows one to increase the available information by using more than one flood peak per year. In this paper, the analysis of continuous streamflow data is reconsidered from the beginning: a filtered peaks over threshold (FPOT) procedure is proposed as an alternative to the PDS approach, and objective criteria are devised for choosing a reasonable threshold and for determining the average annual number of events λ. The revised procedure demonstrates that there is no need for specific limitations on the magnitude of λ to preserve the basic hypotheses of the marked point process build in the PDS procedure. The proposed FPOT method is applied to 33 time series of daily runoff from rivers of northwestern Italy. Significant advantages over the classical PDS method are demonstrated, both in terms of physical interpretability of the parameters and efficiency of the estimates.
Backarc volcanism along the en echelon seamounts: The Enpo seamount chain in the northern Izu‐Ogasawara arc
Authors: Machida Shiki , Ishii Teruaki
Published: August 2003

We report results of detailed petrological analyses of volcanic rocks from the Enpo seamount chain that reveal the characteristics of volcanism in a backarc en echelon seamount chain in an oceanic island arc setting. We identified two types volcanic rock suites in the Enpo seamount chain based on bulk rock trace element chemistry and compositions of chrome spinels included in olivine phenocrysts of primitive basalts. “More Enriched Suites” (MES) have enriched HFSE compositions (such as Nb, Ta), higher Nb/Zr values, and low Cr# in spinel. “Less Enriched Suites” (LES) have depleted HFSE compositions, lower Nb/Zr values, and high Cr# in spinel. These results require distinct mantle sources with different for the volcanic rocks constituting the Enpo seamount chain. Mineralogical and geochemical analyses show that petrological variations within LES lavas are explained by fractionation with open system magma mixing. In contrast, variations between MES lavas require different mechanisms of magma genesis because petrological variation within this suite cannot be explained by fractionation. MES basalts also exhibit mineralogical evidence for magma mixing. Volcanism on the Enpo seamount chain is characterized by complex spatial and temporal relationships between MES lavas consisting of subalkaline basalt, alkaline andesite, and hornblende (water rich) andesite, and LES lavas consisting of subalkaline basalt and fractionated andesite. We suggest that these features are characteristic of variability within magma systems that feed backarc seamount chains in oceanic island arcs.
Sulfate oxygen‐17 anomaly in an Oligocene ash bed in mid‐North America: Was it the dry fogs?
Authors: Bao Huiming , Thiemens Mark H. , Loope David B. , Yuan Xun‐Lai
Published: August 2003

The oxygen and sulfur isotope compositions of sulfate, particularly the oxygen‐17 anomaly, provide clues to the origin of sulfate. We report a variable oxygen‐17 anomaly for water‐ and acid‐leached sulfate from an Oligocene volcanic ash bed in the northern High Plains, U.S.A. We find no sulfate O‐17 anomaly, however, in freshly collected ashes from recent eruptions around the world. The Oligocene paleoclimatic and sedimentary evidence argues against a hyperarid condition in the High Plains, thus a long‐term background atmospheric sulfate accumulation is less likely the origin. Combining sulfur isotope data, we suggest that the anomalous sulfate was associated with volcanic eruptions in the west, but was not directly carried by ash‐falls. Extreme dry‐fog (sulfate haze) events resulting from tropospheric oxidation of volcanic sulfur gases might provide a viable explanation for the sulfates in the ash bed that carry the oxygen‐17 anomaly.
Deposition of acetonitrile to the Atlantic Ocean off Namibia and Angola and its implications for the atmospheric budget of acetonitrile
Authors: Jost C. , Trentmann J. , Sprung D. , Andreae M. O. , Dewey K.
Published: August 2003

We performed airborne measurements of acetonitrile, carbon monoxide, and meteorological parameters in the marine boundary layer and the free troposphere over the South Atlantic Ocean off the Namibian and Angolan coast. The acetonitrile molar mixing ratio in the free troposphere was enhanced due to biomass burning emissions from the continent. In sharp contrast, the marine boundary layer was strongly depleted in acetonitrile with mixing ratios markedly below typical background conditions. This points to significant uptake of acetonitrile by the Atlantic Ocean near Namibia and Angola. We estimate the dry deposition velocity of acetonitrile to be of the order of 0.4 cm s−1. Based on these results and other acetonitrile measurements, we examine the global budget of acetonitrile. This budget is not balanced when the known source and sink strengths are applied, suggesting a missing source of acetonitrile of ∼0.6 Tg a−1(equivalent to 0.2 Tg a−1 nitrogen).
Critical grid size for simulating convective storms: A case study of the Del City supercell storm
Authors: Noda A. , Niino H.
Published: August 2003

The dependence of a numerically‐simulated ‘Del City’ supercell storm on grid size is studied. A reference run with the grid size of 0.5 km successfully reproduces the supercell as demonstrated in the previous studies. In this sensitivity study, the grid size is varied from 1.0 km to 3.0 km with an interval of 100 m. When the grid size is less than 2.5 km, the storm evolves in a manner qualitatively similar to the reference run. When it is larger than 2.5 km, however, the evolution of the storm changes drastically because of an insufficient estimation of the shear‐induced dynamic pressure. The present “critical grid size” is much smaller than that expected from the former sensitivity studies. Thus, one has to be more careful in choosing the grid size when performing a prediction of mesoscale convective systems, the behavior of which depends strongly on the behavior of individual meso‐γ‐scale convective storms.
The Tibetan Plateau as amplifier of orbital‐scale variability of the East Asian monsoon
Authors: Liu Xiaodong , Kutzbach John E. , Liu Zhengyu , An Zhisheng , Li Li
Published: August 2003

Asian monsoon climate variability at geological time scales is modulated by both the Earth's orbital changes and tectonic uplift of the Tibetan Plateau (TP). Here, using bandpass‐filtered versions of previously‐published high‐resolution geological records from Chinese loess, we show that the orbital‐scale variability of the East Asian summer monsoon (EASM) has increased dramatically since the late Pliocene. Climate model simulations indicate that the increase in the variability of the northern EASM at both precession and tilt periods may be, at least partially, attributed to the uplift of the TP.
Detection of a D″ discontinuity in the south Atlantic using PKKP
Authors: Rost Sebastian , Revenaugh Justin
Published: August 2003

A strong arrival in the early coda of major‐arc PKKPab is observed on recordings of earthquakes in the Banda Sea region from the short‐period, small‐aperture Yellowknife array. The arrival has a move‐out close to PKKPab with an average delay of ∼12 s. We show that the phase is most likely an underside reflection from a D″ discontinuity above the PKKP reflection point at the core‐mantle boundary beneath the southern Atlantic on the edge of the African superplume. Differential travel times between PKKPab and PKdKP (the underside reflection at the D″ discontinuity) is used to constrain potential D″ velocity models. The high amplitude of PKdKP requires proximity to the b‐caustic adding further velocity control. We find that a P‐velocity model with a sharp positive velocity jump ∼280 km above the core‐mantle boundary, and a negative velocity gradient closer to the core‐mantle boundary, fits the data well.
Inner magnetospheric plasma pressure distribution and its local time asymmetry
Authors: Lui A. T. Y.
Published: August 2003

Distribution of plasma pressure in the inner magnetosphere for protons and oxygen ions is constructed using measurements from two particle instruments on AMPTE/CCE covering an energy range of ∼1 keV to 4 MeV. Data within the L shells from 2 to 9 in the equatorial region are sorted into low and high activity levels based on the Kp index. It is found that (1) the pressure peak of protons, the dominant contributor to the total plasma pressure typically, occurs at a lower L shell than that of oxygen ions at all local times, (2) proton pressure is generally higher in the dusk‐midnight sector than in the post‐midnight sector during high Kp, a feature reinforced by the expected local time asymmetry in the magnetic field strength, and (3) a minimum magnetic field region seems to exist at L ∼ 8 in the night sector during high Kp but is apparently absent during low Kp. These results suggest that the plasma pressure peak lies in the dusk‐midnight sector during active periods, in contrast to the plasma pressure distribution inferred from energetic neutral atom observations during active times. Possible resolutions to this apparent discrepancy are suggested. This study also indicates that within L ∼ 9 a minimum magnetic field region does not develop during low Kp but appears at high Kp.
Conductivity structure of the San Andreas fault, Parkfield, revisited
Authors: Park Stephen K. , Roberts Jeffery J.
Published: August 2003

A previous interpretation of a high resolution magnetotelluric profile across the San Andreas fault at Parkfield attributed an anomalously conductive region just west of the fault and extending to depths of 3 km to fractured rock saturated with brines. Laboratory measured electrical resistivities of samples of sedimentary rocks known to border the fault to the east are comparable to resistivities of the anomalous zone. We suggest that the anomalous region results from conductive sedimentary rocks in a plunging syncline that is adjacent to the fault, rather than caused by fractured rock. If correct, the current surface trace of the San Andreas fault at Middle Mountain does not form the boundary between the Salinian block and the North American plate. Instead, that boundary is ∼1 km west and collocated with current seismicity.