bluuebunny/crossref_metadata_2025 huggingface dataset:
Individual and familial characteristics of youths involved in street corner gangs in Singapore
Authors: Kee C , Sim K , Teoh J , Tian C.S , Ng K.H
Published: July 2003

Thirty‐six youths involved in street corner gangs in Singapore were compared with 91 age‐matched controls on measures of self‐esteem, aggression, dysfunctional parenting and parent–adolescent communication. Results revealed that gang youths had lower self‐esteem and higher levels of aggression than controls. Of note were the findings that gang youths reported a relative absence of parental abuse and indifference, and experienced less open communication and higher levels of over‐control with their mothers, but not fathers. These findings diverge from anticipated familial correlates of antisocial activity in youths and were discussed with reference to cultural factors and their implications on prevention and intervention.
Gender differences in changes in and stability of conduct problems from early adolescence to early adulthood
Authors: Storvoll Elisabet E. , Wichstrøm Lars
Published: July 2003

The present paper examines whether there are gender differences in changes in the aggregate level and individual stability of conduct problems from early adolescence to early adulthood. We analysed self‐reported data collected as part of a longitudinal general population study of Norwegian adolescents (n=1234). The analyses showed that involvement in conduct problems for both genders peaked in mid‐adolescence. The extent to which this peak reflected changes in the number of participants or differences in the frequency of problems among the participants varied according to gender. In most cases, the individual stability of involvement in conduct problems was similar for girls and boys. However, in the long term, relative involvement was more stable for boys than for girls. Moreover, the proportion of boys who showed a high level of involvement both during adolescence and early adulthood was greater than for girls.
Communication about contraception and knowledge of oral contraceptives amongst Norwegian high school students
Authors: Hansen Thomas , Skjeldestad Finn Egil
Published: July 2003

Communication about contraception and specific knowledge of oral contraceptives (OCs) were examined in a sample (n=4650) of Norwegian high school students. Data were collected through a 44‐item questionnaire especially developed for the study. The response rate was 73% and data from a total of 1714 girls and 1389 boys were eligible for analyses. More females (83%) than males (54%) discussed contraception at least monthly. Discussions were predominantly held with peers and not adults. Females were far more knowledgeable about OCs than males. Respondents knew more about side effects and the pill's relative efficacy than about risks of cancer and tromboembolism. The most significant predictors of high knowledge scores were gender and OC use (females). Also predictive of high knowledge scores were frequent discussions about contraception with peers. Talks about contraception with health workers were unrelated to knowledge scores.
Parental practices in late adolescence, a comparison of three countries: Canada, France and Italy
Authors: Claes Michel , Lacourse Eric , Bouchard Céline , Perucchini Paula
Published: July 2003

The objective of this study was to examine parental practices, such as affection, control and conflict, in three countries: Canada, France and Italy. The sample was composed of more than 900 late adolescents with an average age of 17 years, from three large cities: Montreal, Paris and Rome. Participants answered a self‐report questionnaire that assessed five measures: emotional bonds with the father and mother, parental supervision, tolerance towards friends, punitiveness for violation of rules, and conflict frequency. Analyses of the results indicated that the country of origin discriminated for most of the parental practice dimensions. Canadian adolescents considered their parents to be more tolerant and rated them as using less punitive measures when rules were broken. Canadian parents also seemed to adopt comparable norms for boys and girls, which could be interpreted as a form of sexual egalitarianism, whereas Italian and French parents appeared less tolerant towards girls. Italian adolescents reported strong emotional bonds with each parent, and also identified more conflicts in their relationships with parents. French adolescents reported weaker emotional bonds with each parent and less parental supervision. Results were interpreted in the light of studies that have reported an influence of cultural background on both parental practices and parental decisions in each of these countries.
Differing susceptibility of anadromous brown trout (Salmo trutta L.) populations to salmon louse (Lepeophtheirus salmonis (Krøyer, 1837)) infection
Authors: Glover K.A , Skaala Ø , Nilsen F , Olsen R , Teale A.J , Taggart J.B
Published: July 2003

Three Norwegian sea trout (Salmo trutta L.) stocks and a farmed Atlantic salmon (Salmo salar L.) stock were challenged with salmon lice (Lepeophtheirus salmonis (Krøyer, 1837)), in a “common garden” experiment. Sea trout from the River Guddal exhibited a significantly lower level of infection, as measured by louse abundance and louse density, than other stocks. In addition, salmon lice developed significantly more slowly on the Guddal stock than on the other stocks. Salmon louse abundance and density were similar for the Rivers Fortun and Sima stocks of sea trout, and abundance of lice, though not density, was highest for farmed Atlantic salmon. Within stocks, there were no differences in infection levels of salmon louse between mature and immature fish, between sexes, or between anal-fin-clipped and non-clipped salmon. Differences in infection level among the sea trout stocks may, it is suggested, reflect genetic differences.
An ecosystem model of food web and fisheries interactions in the Baltic Sea
Authors: Harvey Chris J , Cox Sean P , Essington Timothy E , Hansson Sture , Kitchell James F
Published: July 2003

Because fisheries operate within a complex array of species interactions, scientists increasingly recommend multispecies approaches to fisheries management. We created a food web model for the Baltic Sea proper, using the Ecopath with Ecosim software, to evaluate interactions between fisheries and the food web from 1974 to 2000. The model was based largely on values generated by multispecies virtual population analysis (MSVPA). Ecosim outputs closely reproduced MSVPA biomass estimates and catch data for sprat (Sprattus sprattus), herring (Clupea harengus), and cod (Gadus morhua), but only after making adjustments to cod recruitment, to vulnerability to predation of specific species, and to foraging times. Among the necessary adjustments were divergent trophic relationships between cod and clupeids: cod exhibited top-down control on sprat biomass, but had little influence on herring. Fishing, the chief source of mortality for cod and herring, and cod reproduction, as driven by oceanographic conditions as well as unexplained variability, were also key structuring forces. The model generated many hypotheses about relationships between key biota in the Baltic Sea food web and may ultimately provide a basis for estimating community responses to management actions.
GLIA: A reassessment based on novel data on the developing and mature central nervous system
Authors: Villegas Santiago Nahuel , Poletta Fernando Adrián , Carri Néstor Gabriel
Published: July 2003

Several studies on neurobiology have contributed to our understanding of the genesis, survival and death of neurons, unquestionably the stars of the Central Nervous System (CNS). However, they would not be so famous without their close associates: the glial cells. Since novel studies have demonstrated new and important functions for glial cells, they are beginning to gain significant importance in brain research to allow us to reinterpret long known functions on the basis of new concepts. Here, we review recent progress in our understanding of the role of glial cells in the biology of tissue development and maturation.
Uterine Rupture During VBAC Trial of Labor: Risk Factors and Fetal Response
Authors: O'Brien‐Abel Nancy
Published: July 2003

For the woman with a prior uterine scar, neither repeat elective cesarean birth nor vaginal birth after cesarean birth (VBAC) trial of labor (TOL) is risk‐free. When VBAC‐TOL is successful, it is associated with less morbidity than repeat cesarean birth. However, when VBAC‐TOL fails due to uterine rupture, severe consequences often ensue. The challenge for clinicians today is to provide women who desire TOL after cesarean birth, a more individualized risk assessment of uterine rupture, thereby enhancing success and optimizing outcome. This article examines major risk factors for uterine rupture during VBAC‐TOL. In addition, fetal response to uterine rupture and neonatal outcomes are reviewed.
Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk, 6th Edition
Authors: Van Hoover Cheri , Briggs Gerald G. , Freeman Roger K. , Yaffe Sumner J. , Williams Lippincott , Wilkins
Published: July 2003

Reviewed by: Mary Brucker, CNM, DNSc, Parkland School of Nurse‐Midwifery, Dallas, TX.
Giving Birth: A Journey Into the World of Mothers and Midwives
Authors: Taylor Catherine , Churchill Robyn
Published: July 2003

New York: Berkley Publishing Group, 2002. 300 pages. $14.95, paperback. Reviewed by: Robyn Churchill, BA, BSN, MSN, CNM, WomenCare, Arlington, MA.
Internal wave variability in the Beaufort Sea during the winter of 1993/1994
Authors: Halle Chris , Pinkel Robert
Published: July 2003

Acoustic Doppler current profiler observations were obtained at the Sea Ice Mechanics Initiative Ice Camp as it drifted through the Beaufort Sea over the winter of 1993–1994. In this paper, the variability of the internal wave field is examined. Initially (December 1993–January 1994), the camp drifted westward through the central Canada Basin (75°N, 139°–153°W). Numerous anticyclonic baroclinic eddies were encountered. Internal wave energy levels averaged 1/25 of the Garrett‐Munk (GM) standard. Shear variance averaged 1/17 GM. During February–March 1994, the camp drifted meridionally along 156°W (near the Northwind Ridge), reversing direction several times. Large baroclinic vortices were not detected. Internal wave energy levels were significantly greater during this period, peaking at 1/6 GM. Shear variance peaked at 1/3 GM. The waves were predominantly near inertial, resulting from three distinct surface generation events. Downward vertical energy fluxes ranged from typical values of 0.02 mW/m2 to a peak value of 0.15 mW/m2. Two thirds of the downward flux was associated with waves of vertical scale greater than 55 m; the remainder with smaller‐scale waves. Upward energy fluxes ranged from 0.02 mW/m2 (typical) to 0.10 mW/m2 (peak), supported almost entirely by the larger‐scale waves. High ice‐water relative velocities (atmospheric storms), accompanied by ice deformation, appear to be necessary, but not sufficient, to assure a downward propagating wave generation event. The highly variable mesoscale has a significant effect on the near‐inertial wave field propagation. The data suggest that the vertical propagation of near‐inertial waves is strongly affected by the depth variation of the vertical component of mesoscale vorticity. The large Beaufort Sea vortices appear to have a dual effect on the wave field. Enhanced vertical propagation speed (and decreased energy density) is found in the negative vorticity cores. Propagation into the positive vorticity regions surrounding the cores is inhibited. The increase in wave energy experienced as the ice camp left the central Beaufort Sea is jointly associated with the passage of storms and the absence of large baroclinic vortices over the Northwind Ridge.
Variations in the light absorption coefficients of phytoplankton, nonalgal particles, and dissolved organic matter in coastal waters around Europe
Authors: Babin Marcel , Stramski Dariusz , Ferrari Giovanni M. , Claustre Herve , Bricaud Annick , Obolensky Grigor , Hoepffner Nicolas
Published: July 2003

We measured the absorption properties of phytoplankton, nonalgal particles (NAP), and colored dissolved organic matter (CDOM) at about 350 stations in various coastal waters around Europe including the English Channel, Adriatic Sea, Baltic Sea, Mediterranean Sea, and North Sea. For comparison, we also collected data in the open ocean waters of North Atlantic. The exponential slope of the CDOM absorption spectrum varied within a narrow range around 0.0176 nm−1 (SD = 0.0020 nm−1). When data from all the regions were considered altogether, the relationship between phytoplankton absorption and chlorophyll concentration was generally similar to the one previously established for open oceanic waters. Our coastal data, however, show that significant departures from the general trend may occur due to peculiar pigment composition and cell size. In some coastal areas, high phaeopigment concentrations gave rise to especially high blue‐to‐red ratio of phytoplankton absorption. The NAP absorption covaried with the particle dry weight. Most absorption spectra of these particles were well described by an exponential function with a slope averaging 0.0123 nm−1 (SD = 0.0013 nm−1). In some highly turbid waters, the spectra exhibited a signature possibly associated with iron oxides. In the Baltic Sea, NAP absorption systematically showed lower values at wavelengths shorter than 440 nm than predicted from the fitted exponential function. Overall, the variability in the absorption properties of European coastal waters showed some consistent patterns despite the high diversity of the examined waters. Distinct features were identified in the phytoplankton and NAP components. An absorption budget is presented and parameterizations are proposed.
Estimation of heat and salt storage variability in the Indian Ocean from TOPEX/Poseidon altimetry
Authors: Shi Wei , Subrahmanyam Bulusu , Morrison John M.
Published: July 2003

Heat and salt storage variability in the upper 1000 m of the Indian Ocean is investigated using a combination of sea level anomalies derived from TOPEX/Poseidon altimetry (1993–2000), Reynold's sea surface temperature and monthly climatological hydrographic data (World Ocean Atlas 1998) [Antonov et al., 1998; Boyer et al., 1998]. This new technique allows extension of surface information from altimetric observations to study subsurface variability. Hydrographic data collected in the Indian Ocean during the World Ocean Circulation Experiment are used to evaluate and validate this technique. The results show that the Indian Ocean experienced larger changes in heat storage than in salt storage. Significant differences are found between the 8‐year mean seasonal heat storage and the climatological seasonal heat storage, which are attributed to interannual variability, while the 8‐year mean seasonal salt storage agrees well with the climatological seasonal salt storage. The variabilities of heat and salt storages are not synchronized in either space or time because of different control mechanisms. The first four empirical orthogonal function (EOF) modes explain nearly 60% of total variance of heat storage variability with the Indian Ocean dipole outweighing the other processes. The dominant first EOF mode for salt storage, which is attributed to the seasonal variability, explains 33% of its total variance. The heat (salt) storage dipole index, representing the heat (salt) storage difference between the west and east equatorial Indian Ocean during the 1994–1995 and 1997–1998 dipole periods, is of the same order as that of the seasonal heat (salt) storage variability.
Quasigeostrophic models of convection in rotating spherical shells
Authors: Aubert Julien , Gillet Nicolas , Cardin Philippe
Published: July 2003

The use of a quasigeostrophic, two‐dimensional approximation in the problem of convection in a rapidly rotating spherical shell has been limited so far to investigations of the qualitative behavior of the solution. In this study, we build a quasigeostrophic model that agrees quantitatively with full three‐dimensional solutions of the onset of convection in the case of differential heating. Reducing the dimensionality of the problem also permits the simulation of finite amplitude regimes of convection, up to quasigeostrophic turbulence. The nonlinear behavior of the system is studied in detail and compared to ultrasonic Doppler velocimetry measurements performed in a convecting, rapidly rotating spherical shell filled with water and liquid gallium. The results are quantitatively satisfactory and open the way to less computer‐demanding, and still accurate, simulations of the geodynamo.
Fate of mantle plume material trapped within a lithospheric catchment with reference to Brazil
Authors: Sleep Norman H.
Published: July 2003

Local regions of thin lithosphere act as catchments of hot buoyant plume material. Unless replenished, the trapped plume material cools by convection to the mantle adiabat by several tens of million years. In particular, currently hot material from the ∼130 Ma, Paraná starting plume head is unlikely to supply 85 Ma to recent volcanism on the mainland of Brazil and the Martin Vaz and Fernando hot spots. Rather, a plume tail may now underlie southern Brazil where tomographic studies detect conduit‐shaped velocity anomaly through the upper mantle. If the tomographic study in fact found a plume tail, the track crossed the Amazon rift at ∼85 Ma and (since then) lateral flow along thin regions of the lithosphere from the tail fed widespread feeble volcanism including the flow line hot spots of Martin Vaz and Fernando.
Climate change of Mars‐like planets due to obliquity variations: implications for Mars
Authors: Nakamura Takasumi , Tajika Eiichi
Published: July 2003

The obliquities of the terrestrial planets could have undergone large‐amplitude fluctuations. Because the obliquity changes affect the latitudinal distribution of solar radiation, they may have played important roles in the climatic evolution of the planets. We have investigated the effects of obliquity changes on the climate of Mars‐like planets with CO2 atmosphere by using a one‐dimensional energy balance climate model. Our numerical results show that the obliquity changes would result in the drastic changes of atmospheric pressure (climate jumps) by runaway sublimation of permanent CO2 ice. We also found that given a small solar constant and large obliquity, “ring‐shaped” regions with permanent CO2 ice forms at the mid‐latitude.
Solar variations in extremely low frequency propagation parameters: 2. Observations of Schumann resonances and computation of the ELF attenuation parameter
Authors: Kulak A. , Kubisz J. , Michalec A. , Zięba S. , Nieckarz Z.
Published: July 2003

Observations of resonant electromagnetic fields caused by global lightning activity are employed in determining the averaged parameters of the lower ionosphere. Using the two‐dimensional telegraph equation (TDTE) transmission line model described by Kuak et al. [2003], we have computed the attenuation rate of the Earth‐ionosphere waveguide from diurnal observations of the N‐S magnetic component of the ELF field performed irregularly for 6 years in the East Carpathian mountains. As the measurements were carried out during both the minimum and the maximum of the solar cycle 23 we present how solar activity influence the first Schumann resonance frequency and the attenuation rate. The analysis of all the data indicates that the first Schumann resonance frequency increases from 7.75 Hz at solar minimum to about 7.95 Hz at solar maximum while the global mean attenuation rate α at 8 Hz varies from 0.31 dB/Mm at minimum to about 0.26 dB/Mm at maximum.
Conjugate phase studies of ULF waves in the Pc5 band near the cusp
Authors: Liu Y. H. , Fraser B. J. , Liu R. Y. , Ponomarenko P. V.
Published: July 2003

Conjugation of geomagnetic field lines at magnetic high latitude is variable, depending on solar wind and interplanetary magnetic field conditions. In this paper the geomagnetic conjugate point of a location under closed field lines near the cusp has been determined dynamically by examining the conjugate phase relation of ultra low frequency (ULF) waves in the Pc5 band using magnetometer data from high‐latitude ground stations at Longyearben (LYR), Hornsund (HOR), and Hopen Island (HOP) in the Northern Hemisphere and Davis (DAV), Zhongshan (ZHS), and Mawson (MAW) in the Southern Hemisphere. Cross‐spectral and coherency analysis methods are used to select conjugate Pc5 events and derive phase relations. The results show that near the cusp the geomagnetic field lines resonate mainly in the odd mode with the D component out of phase and the H component in phase, when observed at the two ends of the field line. Assuming this phase characteristic, the conjugate of LYR is typically located in the DAV/ZHS‐region and mainly east of Davis by about 10° CGM longitude. In a reverse mapping analysis the conjugates of ZHS and DAV are located in the LYR region, mainly west of LYR by 10°. These results are qualitatively consistent with corresponding locations derived from the Tsyganenko [1996] (T96) model. The relationship of the longitude movement of the conjugate of LYR with respect to the variation of IMF By is quantitatively consistent with the T96 model. However, the expected position of the conjugate site of LYR (DAV/ZHS) derived from Pc5 phase for By = 0 is moved westward (eastward) by about 10° CGM in longitude or ∼300 km from that predicted by the T96 model.
Electrodynamics of a substorm‐related field line resonance observed by the Polar satellite in comparison with ground Pi2 pulsations
Authors: Keiling A. , Kim K.‐H. , Wygant J. R. , Cattell C. , Russell C. T. , Kletzing C. A.
Published: July 2003

Observations from the Polar satellite during a substorm on 29 August 1996 are used to characterize electrodynamic properties of a nightside field line resonance (FLR). A negative H bay and Pi2 pulsations were simultaneously observed at midlatitude SAMNET ground stations (L = 2.6 − 4.5, ∼0000 MLT). During the pulsations, Polar was moving outbound on a 0330 MLT meridian and crossing L shells from 4 to 5.3. While in the central plasma sheet and outside the plasmasphere, Polar recorded toroidal standing waves for ∼20 min starting simultaneously with the ground pulsations. The magnetic‐field‐aligned Poynting flux associated with the FLR was ≤4 μW m−2. Whereas on the ground at L ≤ 4, the Pi2 frequency remained nearly constant and was similar for all stations, the toroidal frequency of the in situ FLR (L ≥ 4) decreased as the satellite crossed field lines with increasing L value. Although this L dependence of frequency of in situ FLR has been inferred in previous studies using multiple satellites at different local times, the 29 August 1996 event directly confirms this frequency dependence for substorm‐related FLR over a large L range on the same meridian. Furthermore, ground (L ≤ 4) and satellite (L ≥ 4) observations allow for the possibility that the oscillations were manifestations of two different magnetospheric oscillation modes, resulting from the same initial magnetospheric disturbance.
The extreme magnetic storm of 1–2 September 1859
Authors: Tsurutani B. T. , Gonzalez W. D. , Lakhina G. S. , Alex S.
Published: July 2003

The 1–2 September 1859 magnetic storm was the most intense in recorded history on the basis of previously reported ground observations and on newly reduced ground‐based magnetic field data. Using empirical results on the interplanetary magnetic field strengths of magnetic clouds versus velocities, we show that the 1 September 1859 Carrington solar flare most likely had an associated intense magnetic cloud ejection which led to a storm on Earth of DST ∼ −1760 nT. This is consistent with the Colaba, India local noon magnetic response of ΔH = 1600 ± 10 nT. It is found that both the 1–2 September 1859 solar flare energy and the associated coronal mass ejection speed were extremely high but not unique. Other events with more intense properties have been detected; thus a storm of this or even greater intensity may occur again. Because the data for the high‐energy tails of solar flares and magnetic storms are extremely sparse, the tail distributions and therefore the probabilities of occurrence cannot be assigned with any reasonable accuracy. A further complication is a lack of knowledge of the saturation mechanisms of flares and magnetic storms. These topics are discussed in some detail.
Aluminum in magnesium silicate perovskite: Formation, structure, and energetics of magnesium‐rich defect solid solutions
Authors: Navrotsky Alexandra , Schoenitz Mirko , Kojitani Hiroshi , Xu Hongwu , Zhang Jianzhong , Weidner Donald J. , Jeanloz Raymond
Published: July 2003

MgSiO3‐rich perovskite is expected to dominate Earth's lower mantle (pressures >25 GPa) with iron and aluminum as significant substituents. The incorporation of trivalent ions, M3+, may occur by two competing mechanisms: MgA + SiB = MA + MB and SiB = AlB + 0.5 (vacancy)O. Phase synthesis studies show that both substitutions do occur and the nonstoichiometric or defect substitution is prevalent along the MgSiO3‐MgAlO2.5 join. Lattice parameters associated with the first substitution (stoichiometric) show more rapid increases with increasing Al content than those for the second substitution (nonstoichiometric), consistent with the differences in size of substituting ions. Oxide melt solution calorimetry has been used to compare the energetics of both substitutions. The stoichiometric substitution, represented by the reaction 0.95 MgSiO3 (perovskite) + 0.05 Al2O3 (corundum) = Mg0.95Al0.10Si0.95O3 (perovskite), has an enthalpy of −0.8 ± 2.2 kJ/mol. The nonstoichiometric reaction, 0.90 MgSiO3 (perovskite) + 0.10 MgO (rocksalt) + 0.05 Al2O3 (corundum) = MgSi0.9Al0.1O2.95 (perovskite) has a small positive enthalpy of 8.5 ± 4.6 kJ/mol. Configurational T ΔS terms play a role in both substitutions. The defect substitution is not prohibitive in enthalpy, entropy, or volume, is favored in perovskite coexisting with magnesiowüstite and may significantly affect the elasticity, rheology, and water retention of silicate perovskite in Earth.
Mantle metasomatism and rapid ascent of slab components beneath island arcs: Evidence from 238U‐230Th‐226Ra disequilibria of Miyakejima volcano, Izu arc, Japan
Authors: Yokoyama Tetsuya , Kobayashi Katsura , Kuritani Takeshi , Nakamura Eizo
Published: July 2003

238U‐230Th‐226Ra systematics in lavas from Miyakejima volcano, Japan, are presented to estimate the timescale of magmatic processes beneath an island arc. Miyakejima volcano has four recent eruptive stages (Stages 1–4) starting >7000 BP. 238U‐230Th‐226Ra disequilibria observed in lavas with large 238U and 226Ra excesses imply metasomatism of depleted mantle by fluid‐related processes. This metasomatism is also suggested by trace element and Sr‐Nd‐Pb isotopic systematics in the same lavas. In the equiline diagram, the trends for two magmatic stages (Stages 1 and 2) are regarded as two different isochrons with a common initial (230Th/232Th) ratio, although the trend for Stages 3 and 4 is a magma mixing line. Our model calculations show that slab‐derived fluids can deliver some Th and a very rapid ascent time of the slab components in the mantle wedge (< 7 kyr) is inferred. This rapid ascent can be explained by nearly instantaneous material transport in the mantle wedge by a hydrofracture model for fluid and a channel flow model for melt. Such a timescale estimate is not increased even if melting processes that enhance 226Ra are taken into account. The age difference in the equiline diagram corresponds to the interval of individual fluid‐release events (13 kyr between Stages 1 and 2, and 5 kyr between Stages 2 and 3). Thus fluid release from the slab and subsequent magma generation occur as episodic events on a several‐kiloyear timescale.
Diurnal variations of sea surface temperature over the wide‐ranging ocean using VISSR on board GMS
Authors: Tanahashi Shuichi , Kawamura Hiroshi , Takahashi Tomoyuki , Yusa Hiroyuki
Published: July 2003

Sea surface temperature (SST) diurnal warming caused by insolation is investigated using wide‐ranging hourly insolation and SST derived from the Geostationary Meteorological Satellite/Visible and Infrared Spin Scan Radiometer (GMS/VISSR). Using SST diurnal variations (ΔSSTgms) derived from the hourly VISSR SSTs and insolation, and the wind velocity derived from the Advanced Earth Observing Satellite/NASA Scatterometer (ADEOS/NSCAT), it is verified that the SST warming occurs under conditions of high insolation and weak wind. To investigate the ΔSSTgms, two simple models are applied. One SST diurnal warming estimation model (Model A) is developed with reference to Price et al. [1986, 1987] introducing the latitudinal heat loss estimated from climatic values. Another model (Model B) was proposed by Webster et al. [1996]. Because SST diurnal warming is dependent on meteorological conditions, the areas of SST warming change from day to day. However, areas of weak wind and high insolation can be specified by large‐scale atmospheric systems. Both distributions of the monthly averaged ΔSSTmodel‐A (SST diurnal warming estimated by Model A) and ΔSSTgms agree well with each other. Large SST diurnal warming has occurred at middle latitudes in the summer hemisphere and tropical regions near the land. Through this study, it is demonstrated that the combination of satellite observation and numerical models enables us to investigate the diurnal SST warming over the wide‐ranging ocean.
An anomalous late‐season change in the regional sea ice regime in the vicinity of the Mertz Glacier Polynya, East Antarctica
Authors: Massom R. A. , Jacka K. , Pook M. J. , Fowler C. , Adams N. , Bindoff N.
Published: July 2003

This paper examines a major late‐season shift in atmospheric circulation over the East Antarctic sea ice zone that occurred in October 1999. The mean wind direction at 65°S, 145°E changed from south‐southeasterly to west‐southwesterly, resulting in almost a complete reversal of the climatological East Wind Drift pattern in large‐scale sea ice advection over the Southern Ocean sector 135°–170°E. By comparison with National Centers for Environmental Prediction/National Center for Atmospheric Research Reanalysis time series from 1980 to 2000, this shift is shown to be unusual in terms of both its persistence and impact, although similar though less prolonged patterns occurred in 1984 and 1985. Lasting from October 1999 to February 2000, it had a profound impact on sea ice concentration and extent over a vast area. By coinciding with the period of maximum ice extent and persisting through to the springtime melt phase, it also contributed to the rapid annual meltback of sea ice. It also had a large and complex effect on the behavior of the globally important Mertz Glacier Polynya and on the areal extent of thick perennial sea ice to the east. While a midlatitude blocking high pattern provided the initial impetus for the “shift” in 1999, the persistence of west‐southwesterly winds through February 2000 appears to relate to an unusually persistent southward migration of the Antarctic Circumpolar Trough (ACT). In addition to the prolonged 1999 episode, a strong seasonal signal is apparent throughout the mean wind speed and direction time series, related to the ACT migration. Although less persistent than in 1999, this annual shift has implications for the observed dramatic annual meltback of East Antarctic sea ice.
A two‐dimensional Monte Carlo model of radiative transfer in sea ice
Authors: Light B. , Maykut G. A. , Grenfell T. C.
Published: July 2003

A two‐dimensional, Monte Carlo radiative transfer model was developed for the analysis of optical data from cylindrical samples of sea ice. The backward Monte Carlo method was used to solve the radiative transfer equation in a cylindrical, azimuthally symmetric domain. Horizontal layers between two depths and vertical shells between two radii can be used to simulate spatial gradients in scattering, absorption, and refractive index in the model. The top of the cylinder can be illuminated by either normally incident, collimated radiation or by diffuse radiation. Irradiance and radiance detectors can be located anywhere within or on the cylindrical domain. The model was tested by comparing predicted apparent optical properties with solutions from existing one‐dimensional and two‐dimensional radiative transfer models. Domains with the largest optical depths and smallest radii were found to be impacted most by the horizontally finite geometry. The model was used to interpret backscattered and transmitted spectral radiance data taken in the laboratory from cylindrical core samples of first‐year sea ice at −15°C. Use of a similarity parameter facilitated comparison between observations and model predictions by reducing the number of independent variables by one. Concurrent observations of ice microstructure indicated that light scattering due to inclusions of brine, gas, and precipitated salts should result in a scattering coefficient of ∼4.6 cm−1 in our samples. Combining this value with the inferred similarity parameter yielded an asymmetry parameter of 0.98 for first‐year sea ice at −15°C. Agreement between observed and predicted spectral radiances demonstrates the viability of this model as a tool for analyzing the optical properties of samples with finite geometry.
Measurements of turbulent transfer in the near‐surface layer over a rice paddy in China
Authors: Gao Zhiqiu , Bian Lingen , Zhou Xiuji
Published: July 2003

Eddy covariance measurements were conducted on fluxes of moisture, heat, and CO2 in a near‐surface layer over a rice paddy in the central plain of China from 10 June to 20 July 2001. During this period, the canopy height increased from 0.16 to 0.65 m. The study site, typical of the agricultural region in China, was ∼600 m × 600 m, was surrounded by similar rice paddies and was flooded throughout the entire experiment. We estimated the zero plane displacement and the roughness length at the end of the experiment to be 0.43 m and 0.027 m, respectively. Aerodynamic roughness length increased with increasing wind speed when the rice height was >0.5 m. On the basis of footprint analysis, we expected >90% of the measured flux (at a height of 3 m above water) to occur within the nearest 600 m of upwind area. We examined daily and seasonal variations in the components of the surface energy balance and in CO2 flux. Results show that the pattern of energy partition had no obvious variation during the season. Daytime absorption and nighttime release of CO2 flux by the rice paddy gradually increased as the rice grew. We examined the energy budget closure and found it to be around 0.91. We tested the extended Louis scheme using eddy covariance techniques. It estimated surface stress in good agreement with direct measurements. However, on average, this scheme underestimated sensible heat flux by 10% and latent heat flux by 11%.
Structural characteristics of rain fields
Authors: Mesnard Frédéric , Sauvageot Henri
Published: July 2003

This paper analyzes the shape of rain area size distributions (RASDs) observed by radar in tropical and midlatitude regions. The rain area is defined, with respect to a rain threshold τ, as the area, inside a contour, where the rain rate is higher than τ. The size considered is the diameter of the equivalent circular area D. The reflectivity peaks inside the rain areas are numbered and the rain areas put together by classes having the same peak number. The size distributions of the rain areas containing the same number of peaks p are well fitted by lognormal functions, the parameters of which, μp and σp, are weakly dependent on the conditions of the peak determination. The parameters μp and σp are found to be linked by a power relation. For D < 6 km most of the rain areas are single peaked. The RASD without peak number distinction is a lognormal mixture. Using the relations obtained for μp, σp, and the rain area number as functions of p enables one to simulate RASDs with results in good agreement with the observations. Because of the limitation in the radar sampling at both ends of the RASD and the decrease of area number with increasing size, the radar‐observed RASDs are severely truncated. The possibility of an approximate fitting of the truncated RASD with diverse functions is discussed. At the intermediary values of the threshold, i.e., for τ ranging between 3 and 12 mm h−1, where the RASD is easiest to compute, the slope of these truncated distributions is not strongly dependent on the threshold. This slope appears not to be very sensitive to the minimum and maximum distances bounding the domain where the rain field is observed. The RASD is found to be sloping more over sea than over land. The slope of the RASDs shows a small diurnal variation but no significant annual variation. The “perimeter to area” (fractal) dimension of the rain area for the sample without peak number distinction is around 1.35. Single‐peaked and multipeaked rain areas have different perimeter to area dimensions, ∼1.23 and 1.38, respectively. These values are almost independent from the threshold and from the location of the domain observed.
Gaseous emissions from flooded rice paddy agriculture
Authors: Redeker K. R. , Meinardi S. , Blake D. , Sass R.
Published: July 2003

Modification of continental land for agricultural use has increased over the last century. Atmospheric impact of this land use change has only been addressed for a few ecosystems and compounds. This paper provides, to date, the most comprehensive examination of gaseous emissions from rice paddies. We report seasonal emission ranges and integrated emission totals for 55 chemical species. This paper is the first to report emissions of isoprene, ethyl chloride, bromoform, alkyl nitrates, bromodichloromethane, hexane, and benzene from rice paddies. Emissions of alkyl nitrates, bromoform, ethyl chloride, and bromodichloromethane by terrestrial ecosystems have never before been observed. For species where emissions were observed we tentatively ascribe possible mechanisms of production; photochemical or biological production in the water column or rice plant mediated. For some compounds, during periods of maximum emissions, ambient rice paddy air concentrations may be concentrated enough to affect regional atmospheric chemistry.
Assessment of multiple scattering and horizontal inhomogeneity in IR radiative transfer calculations of observed thin cirrus clouds
Authors: Joseph Everette , Min Qilong
Published: July 2003

Outgoing longwave (LW) radiation (OLR) and infrared heating rate errors due to the neglect of multiple scattering by clouds and horizontal cloud inhomogeneity in infrared radiative transfer parameterizations are assessed with a modified version of the Fu and Liou [1992] radiative transfer model and field measurements of optically thin cirrus that were observed during the fall 1997 and spring 2000 intensive observation periods conducted at the Atmospheric Radiation Measurement Southern Great Plains site in Oklahoma. A rigorous method is first introduced for incorporating atmospheric and cloud optical and geometric properties derived from measurements in radiative transfer calculations and for ensuring the consistency of these calculations with observations. Part of that method is the use of optical depth derived from measurements of a Multi Filter Rotating Shadowband Radiometer (MFRSR) at 415 nm to determine the cloud ice water content for the longwave and shortwave radiative transfer calculations. The optical depth is corrected to account for forward scattering by cirrus crystals, which is dominant under the thin cirrus conditions observed. Surface downwelling fluxes from the radiative transfer calculations are compared against observations from the Baseline Surface Radiation Network for consistency, with primary emphasis placed on achieving good agreement between the observed and calculated direct normal components. For all cases considered, there is very good agreement in the solar direct irradiance and reasonably good agreement in the solar diffuse irradiance, but without the forward scattering correction the agreement for both would degrade; the diffuse agreement, in particular, would do so by 12 W m−2 (>30%). Very good agreement is achieved in the LW with an absolute mean difference of 0.02 W m−2. For the observed cases considered, neglecting multiple scattering of LW by thin cirrus overestimates OLR by 6–8 W m−2 or less (depending on cloud optical depth and particle size) because of exclusion of reflection of upwelling LW at the cloud base and results in heating rate errors of as much as 0.2 K d−1. The effect of horizontally homogeneous clouds is approximated by employing the half hourly mean of the derived optical and geometric properties in the calculation. The impact of the combined effect on OLR and LW heating rates is shown from these calculations to be as high as 30 to 35 W m−2, and heating rate errors are on the order of 0.5 to over 1 K d−1, which are very significant errors.
A stratospheric aerosol climatology from SAGE II and CLAES measurements: 2. Results and comparisons, 1984–1999
Authors: Bauman J. J. , Russell P. B. , Geller M. A. , Hamill Patrick
Published: July 2003

This paper presents a climatology of the stratospheric aerosol produced with our look‐up table (LUT) technique using data from the Stratospheric Aerosol and Gas Experiment (SAGE II) and the Cryogenic Limb Array Etalon Spectrometer (CLAES) instruments. The LUT climatology spans the period from December 1984 to August 1999. It includes values and uncertainties of measured extinction and optical depth at four SAGE II wavelengths (0.385–1.02 μm) and supplements these with results from the CLAES 12.82 μm wavelength during the key period January 1992 through May 1993, when the large particle sizes from the Pinatubo volcanic injection made many SAGE II extinction and optical depth spectra wavelength independent. Also included are retrieved values of effective radius Reff, distribution width σg, surface area S, and volume V. Aerosol retrievals show notable increases in all these parameters after major volcanic eruptions, with increases in Reff lagging increases in the others. Postvolcanic increases in σg, indicative of broader size distributions, are consistent with sudden increases in numbers of both small and large particles that exceed increases in intermediate‐size particles. After Pinatubo, retrieved Reff and σg took nearly 5 years to return to pre‐eruption values, while slightly shorter recovery times were obtained for S and V. During low‐aerosol‐loading periods, size distributions narrow in going from the tropical core to higher latitudes at altitudes between 20 and 22 km. Seasonal variations in S and V are observed at high latitudes for several altitude bands, but are less obvious in Reff. With some exceptions, LUT retrievals agree well with most previous climatologies. For example, agreement is good between LUT retrieved surface area and results from balloon‐borne measurements, where available. However, there are a few noteworthy discrepancies. For example, values of surface area from principal component analysis of SAGE II data are less than LUT retrievals during near‐background periods (e.g., 1989 to mid‐1991, and after 1996) and greater than LUT retrievals in the peak of the Pinatubo plume. The smaller LUT‐derived surface areas during the Pinatubo peak result from the constraint provided by the CLAES 12.82 μm extinction measurements.
A fast, flexible, approximate technique for computing radiative transfer in inhomogeneous cloud fields
Authors: Pincus Robert , Barker Howard W. , Morcrette Jean‐Jacques
Published: July 2003

Radiative transfer schemes in large‐scale models tightly couple assumptions about cloud structure to methods for solving the radiative transfer equation, which makes these schemes inflexible, difficult to extend, and potentially susceptible to biases. A new technique, based on simultaneously sampling cloud state and spectral interval, provides radiative fluxes that are guaranteed to be unbiased with respect to the benchmark Independent Column Approximation and works equally well no matter how cloud structure is specified. Fluxes computed in this way are subject to random, uncorrelated errors that depend on the distribution of cloud optical properties. Seasonal forecasts, however, are not sensitive to this noise, making the method useful in weather and climate prediction models.
Ages and stratigraphy of mare basalts in Oceanus Procellarum, Mare Nubium, Mare Cognitum, and Mare Insularum
Authors: Hiesinger H. , Head J. W. , Wolf U. , Jaumann R. , Neukum G.
Published: July 2003

Accurate estimates of mare basalt ages are necessary to place constraints on the duration and the flux of lunar volcanism as well as on the petrogenesis of lunar mare basalts and their relationship to the thermal evolution of the Moon. We performed new crater size‐frequency distribution measurements in order to investigate the stratigraphy of mare basalts in Oceanus Procellarum and related regions such as Mare Nubium, Mare Cognitum, and Mare Insularum. We used high‐resolution Clementine color data to define 86 spectrally homogeneous units within these basins, which were then dated with crater counts on Lunar Orbiter IV images. Our crater size‐frequency distribution measurements define mineralogical and spectral surface units and offer significant improvements in accuracy over previous analyses. Our data show that volcanism in the investigated region was active over a long period of time from ∼3.93 to 1.2 b.y., a total of ∼2.7 b.y. Volumetrically, most of the basalts erupted in the Late Imbrian Period between ∼3.3 and 3.7 b.y., and we see evidence that numerous units have been resurfaced. During the Eratosthenian Period, significantly less basalt was erupted. Depending on the absolute model ages that one can assign to the lunar chronostratigraphic systems, five units might be of Copernican age. Younger basalts are generally exposed in the center of the investigated area, that is, closer to the volcanic centers of the Aristarchus Plateau and Marius Hills. Older basalts occur preferentially along the northwestern margin of Oceanus Procellarum and in the southeastern regions of the studied area, i.e., in Mare Cognitum and Mare Nubium. Combining the new data with our previously measured ages for basalts in Mare Imbrium, Serenitatis, Tranquillitatis, Humorum, Australe, and Humboldtianum, we find that the period of active volcanism on the Moon lasted ∼2.8 b.y., from ∼4 b.y. to ∼1.2 b.y. On the basis of the basalts dated so far, which do not yet include the potentially young basalts of Mare Smythii e.g.,all investigated basins but probably also is the location of some of the youngest basalts on the lunar surface.
Hydrothermal activity on the eastern SWIR (50°–70°E): Evidence from core‐top geochemistry, 1887 and 1998
Authors: German Christopher R.
Published: July 2003

Evidence for hydrothermal activity on the eastern SWIR has been reported previously in the form of optical‐backscatter anomalies interpreted to indicate the presence of hydrothermal plumes. Here, I report on a brief reconnaissance analysis of the geochemical composition of core‐top samples collected from sites both beneath and away from those previously‐reported plume signals to determine whether evidence for fall‐out of hydrothermal plume material is discernible. Samples used for this study were collected using the deep‐diving submersible SHINKAI 6500 in 1998 and from the tallow‐coatings applied to lead sounding lines, 111 years earlier, aboard HMS Egeria. The data indicate hydrothermal input to all but one of eight SHINKAI 6500 cores along the length of the eastern SWIR rift‐valley, including the site of strongest previously reported plume anomalies. Comparison with a recent MAR study suggests that the cores analyzed here, however, may predominantly lie distant from any current or recently‐active source of venting.