bluuebunny/crossref_metadata_2025 huggingface dataset:
The Hedging Effectiveness of Stock Index Futures: Evidence for the S&P CNX Nifty Index Traded in India
Authors: Pradhan Kailash
Published: June 2011

The Hedging Effectiveness of Stock Index Futures: Evidence for the S&P CNX Nifty Index Traded in India

This study evaluates optimal hedge ratios and the hedging effectiveness of stock index futures. The optimal hedge ratios are estimated from the ordinary least square (OLS) regression model, the vector autoregression model (VAR), the vector error correction model (VECM) and multivariate generalized autoregressive conditional heteroskedasticity (M-GARCH) models such as VAR-GARCH and VEC-GARCH using the S&P CNX Nifty index and its futures index. Hedging effectiveness is measured in terms of within sample and out of sample risk-return trade-off at various forecasting horizons. The analysis found that the VEC-GARCH time varying hedge ratio provides the greatest portfolio risk reduction and generates the highest portfolio returns.
Differences on Organizational Practices and Preferred Leader Attributes Between Polish Managers Investigated in 1996/1997 and 2008/2009
Authors: Mączyński Jerzy , Łobodziński Andrzej , Wyspiański Dariusz , Kwiatkowski Piotr
Published: June 2011

Differences on Organizational Practices and Preferred Leader Attributes Between Polish Managers Investigated in 1996/1997 and 2008/2009

This study compares Polish managers' perceptions of their organizational culture and their beliefs concerning attributes necessary for leadership effectiveness, investigated in 1996/1997 and 2008/2009. As was unexpected, our results show that Polish managers of 2008/2009 score significantly higher than managers of 1996/1997 on Power Distance, Individualism, Masculinity and slightly lower on Future Orientation and Humane Orientation. Our findings suggest that more individualistic orientation in Polish organizations is still necessary in order to survive and be effective during the current turbulent and highly uncertain economic and business conditions. Relatively higher scores on Power Distance on the part of Polish managers being studied in the years 2008/2009 are also in line with findings concerned with attributes necessary for leadership effectiveness. Mean comparisons on beliefs concerning attributes necessary for leadership effectiveness show that Polish managers of 2008/2009 in comparison with their counterparts studied in 1996/1997 scored higher on Autocratic Orientation, Risk Avoidance, Isolationistic Orientation and Individualistic Orientation. Our findings are also consistent with regard to leadership attributes of Performance Orientation, Team Orientation, Decisiveness, Diplomatic, Humane Orientation, Integrity, Visionary and Charismatic/Inspirational, which are somewhat less strongly associated with leadership effectiveness by Polish middle managers investigated in 2008/2009 in comparison with their counterparts studied in 1996/1997.
How good gets better and bad gets worse: measuring the face of emotion
Authors: Adetoun Bolanle , Tserere Maggie , Adewuyi Modupe , Akande Titilola , Akande Williams
Published: June 2011

How good gets better and bad gets worse: measuring the face of emotion

Given the history of the past, black South African students from different settings face unique academic and emotional climate. Using the Differential Emotions Scale (DES) which focuses on ten discrete emotions, and building upon Boyle's (1984) seminal work, this study reports a repeated-measure multiple discriminant function analysis for individual items across raters. The findings further indicate that majority of the DES items are sensitive indicators of the different innate and universal facial expressions. However, the construct requires revision so that it offers the examiner maximum flexibility in assessment at diverse levels, in terms of more extensive norming and programmatic replication. In brief, the DES potentially has much to offer provided that it is adequately developed for use in non-Western nations or contexts.
Perceived social support and life-satisfaction
Authors: Kasprzak Elżbieta
Published: June 2011

Perceived social support and life-satisfaction

The article concerns the relationship between life-satisfaction and the features of interpersonal relationships and social support. The research presented in this paper concerned the satisfaction with the relationships with family members, friends, colleagues and acquaintances, the extent of the relationships among these groups, and the perceived social support. The aim of the presented research is to assess the impact of these characteristics on life-satisfaction. In addition, the changes that occurred after the social skills training in the level of life-satisfaction and its determinants were examined. The study group consisted of 60 participants. The results show that the strongest determinants of life-satisfaction are practical support and the satisfaction with the relationships with friends. After the social training the structure of the determinants changed. The factors which were relevant before the training appear to be insignificant now; however, the emotional support, satisfaction with family relationships and the number of friends gain in importance. The social skills training was also effective and increased the level of life-satisfaction.
Attention-driven bias for threat-related stimuli in implicit memory. Preliminary results from the Posner cueing paradigm
Authors: Traczyk Jakub , Matusz Paweł , Sobków Agata
Published: June 2011

Attention-driven bias for threat-related stimuli in implicit memory. Preliminary results from the Posner cueing paradigm

An implicit memory advantage for angry faces was investigated in this experiment by means of an additional cueing task. Participants were to assess the orientation of a triangle's peak, which side of presentation was cued informatively by angry and neutral face stimuli, after which they immediately completed an unexpected "old-new" task on a set of the previously presented faces and new, distractor-faces. Surprisingly, the RTs were similarly long on the invalid trials for angry and neutral facial cues in the Posner task. However, performance on the "old-new" task was better for angry than neutral faces. A strong correlation between RTs in angry-invalid trials and confidence ratings for these angry faces was observed only in highly reactive participants. These results suggest that presentation of threatening material can induce enhanced incidental encoding which can result in stronger familiarity for such material, and this effect is driven by attentional bias in highly reactive individuals.
The assessment of the fear of being laughed at in Poland: Translation and first evaluation of the Polish GELOPH<15>
Authors: Chłopicki Władysław , Radomska Anna , Proyer René , Ruch Willibald
Published: June 2011

The assessment of the fear of being laughed at in Poland: Translation and first evaluation of the Polish GELOPH<15>

The main aim of the paper was to translate and, for the first time, evaluate the Polish GELOPH<15>. This is a 15-item questionnaire for the subjective assessment of gelotophobia, the fear of being laughed at. Gelotophobia is seen as an individual differences phenomenon at a sub-clinical level. The psychometric properties of the Polish version were tested in two independently collected samples with a total N of 506 participants. The Polish GELOPH<15> yielded good psychometric properties in terms of high reliability in both samples. The fear of being laughed at existed widely independently from the participants' age, sex, or marital status (being married or living with a partner vs. being single or not living with a partner). The Polish GELOPH<15> can be seen as a reliable instrument for the subjective assessment of gelotophobia for research and practical applications.
Composite Structure of Personal Networks, Age, and Well-being in Poland
Authors: Nowak Krzysztof , Duda Tomasz
Published: June 2011

Composite Structure of Personal Networks, Age, and Well-being in Poland

Traditionally aging research focused on the disintegration of social ties, however it has recently been observed that whom we contact has a larger impact on well-being (Cacioppo et al., 2009). The authors used data from the Social Networks II module of the International Social Survey Programme to investigate the role of social network components in successful aging. A factor analysis on 1221 Polish participants revealed 4 factors that were interpreted as: close, medium, and distant family, and friends. Well-being variables were most strongly related to contact with distant family, while SS variables were most strongly related to friends. Given SS was strongly related to distant family, while perceived SS was strongly related to close family. All family contacts decreased with age, though only distant family contacts were proactively managed. These results indicate the importance of distant family in Poland, in contrast to other countries.
Experimental approach of the single pedestrian-induced excitation
Authors: Kala J. , Bajer M. , Barnat J. , Smutný J.
Published: June 2011

Experimental approach of the single pedestrian-induced excitation

Pedestrian-induced vibrations are a criterion for serviceability. This loading is significant for light-weight footbridge structures, but was established as a basic loading for the ceilings of various ordinary buildings. Wide variations of this action exist. To verify the different conclusions of various authors, vertical pressure measurements invoked during walking were performed. In the article the approaches of different design codes are also shown.
Engineering-geological conditions of the effect of a landslide from mining activity
Authors: Marschalko M. , Hofrichterová L. , Lahuta H.
Published: June 2011

Engineering-geological conditions of the effect of a landslide from mining activity

The paper deals with a slope deformation in Řepiště (Paskov), which is located between the towns of Ostrava and Frýdek Místek; Řepiště is situated in the Ostrava-Karviná District within the reach of the effects of mining activity. The deformation involves the Paskov Mine, which is the only active mine in the Ostrava section of the district. The study included mapping complemented with a geophysical survey using resistance tomography; along with the information obtained from the inspection, it provided an overview of the engineering-geological conditions of the slope deformation. The interpretation of the data obtained identified a very complicated structure, including several levels of slip surfaces. The landslide is thus a textbook example of slope movements with a very complicated geological structure occupying an extensive spatial area in the mining landscape and affecting the stability of a road running directly through its body.
Roof top extensions for multifamily houses in Slovakia
Authors: Szekeres K.
Published: June 2011

Roof top extensions for multifamily houses in Slovakia

In the countries of the European Union with the exception of Malta, approximately 100.1 million multifamily dwelling units are situated. These dwellings count for an average of 47.5% of the total housing stock in European Union countries. At present in Slovakia and also other countries of Central and Eastern Europe, there are vast housing areas which were built after World War II. Slovakia's multifamily housing stock was privatized during the 1990s. Considering that the economy of Slovakia is not capable of replacing the existing housing fund, which is located in the multifamily houses that were built after World War II, it is necessary to place an increased emphasis on the renovation of this housing fund. The expenditures for the refurbishment of multifamily housing stock in recent decades, when compared with the demand, have been at a very low level. The main problems involving the current multifamily housing stock in Slovakia are: the need for modernization, the low level of energy efficiency, and the insufficient level of building maintenance. One of the options for creating sufficient sources for the renovation of apartment buildings is to utilize the roofs of apartment buildings as construction areas for building additional floors (over - roofing). The means acquired from the sale of the new floors after deducting the costs can be used for renovation. It is a matter of a one-time possibility, which is limited by many factors that depend on the localization and constructive technical solutions for apartment buildings.

This article is an outcome of the SuReFit "Sustainable Roof Extension Retrofit for High-Rise Social Housing in Europe" international research project.
A note to a common cause in quantum logic
Authors: Al-Adilee A.
Published: June 2011

A note to a common cause in quantum logic

We study the notion of a common cause in quantum logics as a type of causal relations (see [13]). We review maps like conditional state, s-map as basic tools of our constructions. Finally, we show some properties of such notions in quantum logics.
Analysis of the development of a hydrological balance for future decades in the Senianska depression in the Eastern Slovak lowland
Authors: Tegelhoffová M.
Published: June 2011

Analysis of the development of a hydrological balance for future decades in the Senianska depression in the Eastern Slovak lowland

The goal of the article was to analyze the hydrological balance for future decades in a pilot area in the Eastern Slovak lowland. The aim was to set up the physically-based Mike SHE hydrological model for the modeling hydrological balance in the selected wetland ecosystem in the Eastern Slovak Lowland. The pilot area - the Senianska depression is located near the village of Senne, between the Laborec and Uh Rivers. Specifically, it is a traditional landscape of meadows, marshes, cultivated soil, small water control structures and forests. To get a complete model set up for simulating elements of the hydrologic balance in the pilot area, it was necessary to devise a model for a larger area, which includes the pilot area - the Senianska depression. Therefore, both the Mike SHE model was set up for the Laborec River basin (a model domain of 500 × 500 m) and the Čierna voda River basin (a model domain of 100 × 100 m), for the simulation period of 1981-2007, is order to get the boundary conditions (overland flow depth, water levels, discharges and groundwater table) for the model of the pilot area. The Mike SHE model constructed for the pilot area - the Senianska depression (a model domain of 1 × 1 m) -was used to simulate the elements of the hydrological balance for the existing conditions during the simulation period of 1983-2007 and for climate scenarios for the simulation period of 1983-2100. The results of the simulated elements of the hydrological balance for the existing conditions were used for a comparison of the evolution of the hydrologic conditions in the past, for identifying wet and flooded areas and for identifying the spatial distribution of the actual evapotranspiration in the pilot area. The built-up model with setting values was used for modeling the hydrological balance in changed conditions - climate change.
Measuring the Harm of Illicit Drug Use on Friends and Family
Authors: Melberg Hans Olav , Hakkarainen Pekka , Houborg Esben , Jääskeläinen Marke , Skretting Astrid , Ramstedt Mats , Rosenqvist Pia
Published: June 2011

AIMS

This paper explores different approaches to quantify the human costs related to drug use.

DATA AND METHODS

The data come from a representative survey of 3092 respondents above the age of 18 in four Nordic capitals: Copenhagen, Helsinki, Oslo and Stockholm.

Results

The results show that in most Nordic capitals more than half of the respondents at some time have known and worried about the drug use of somebody they know personally. Moreover, while the average reported harm was about 2 on a scale from 0 to 10, a significant minority (10%) of those knowing drug users indicated that the harm was above 5.

Conclusions

Many persons have at some time personally known somebody who uses drugs. This causes significant human harm and should be included in the estimate of the social cost of illegal drugs. These results are relevant in the debate on the size of the drug problem as well as for targeting groups that experience the highest costs.
In Control and out of Control. The Discourse on Intoxication among Young Finnish Women in the 1980s and 2000s
Authors: Simonen Jenni
Published: June 2011

AIMS

The article focuses on the discourse on intoxication and its changes among young women in Finland. According to surveys, drinking among Finnish women has been rising for decades. Especially young women have been in the front line in the raise of drinking and intoxication-oriented drinking. However, statistics are not able to explain the factors behind this change. What has happened to women's attitudes and connotations related to binge drinking during the past decades? How do young women in their twenties perceive being drunk and how has the description of their relationship to this condition changed over the last 20 years?

Methods and Data

To explore these questions, the present article compares interview materials concerning drinking collected among young adults in 1985 and 2005/2007. The article analyses how young women identify themselves with intoxication in these periods and how the way in which women describe this relationship has changed in the meantime.

Results

The greatest change has to do with how young women regard drunkenness while presenting themselves. Whereas in the 1985 material young women distanced themselves from binge drinking, 20 years later they identify themselves strongly with it. The analysis shows that this development illustrares that both the significance of drunkenness in itself and the way in which drinking-related self-expression has changed.

Conclusions

The results relate to the changes in Finnish drinking culture which have been more pronounced in the case of women than men as well as the change of acceptable and desirable images of femininity.
Activity of Monoamine Oxidases in Rat Female Genital Organs During Preimplantation Period of Pregnancy
Authors: Mihalik J. , Kravcukova P. , Hodorova I. , Vecanova J. , Rybarova S.
Published: June 2011

Activity of Monoamine Oxidases in Rat Female Genital Organs During Preimplantation Period of Pregnancy

Our objectives in the present study were to determine the activity of monoamine oxidases A and B (MAO AB) in rat ovary, oviduct and uterus during preimplantation period of pregnancy. It should help us to clarify and better understand possible involvement of both MAO enzymes in the reproductive process. Pregnant females were killed employing a lethal dose of thiopental on the first (D1), on the third (D3), and on the fifth (D5) days of pregnancy. Rats were perfused transcardially with the PBS to rinse out of the body as much blood as possible. Ovaries, oviducts and uteri were immediately removed and stored until the measurement was done. MAO activity was determined by fluorescent monoamine oxidase detection kit. In the ovaries we have found the highest MAO activity at D3, followed by D1, and the lowest levels were recorded at D5 of pregnancy. In the oviducts, the highest MAO activity was detected again at D3, followed by D5, and by D1 of pregnancy. But statistical analysis did not reveal any difference between individual days of pregnancy nor in the ovaries, neither in uterine tubes. Uteri were the only organs, in which statistically significant differences were detected (p<0.001). The highest activity of MAO was observed at D5, followed by D1, and by D3 of pregnancy. Potential mechanisms responsible for the changed MAO activity in gonads during preimplantation period of pregnancy are proposed.
Evaluation of Surfactant Function: In Vitro and In Vivo Techniques in Experimental Respirology
Authors: Calkovska A. , Mokra D.
Published: June 2011

Evaluation of Surfactant Function: In Vitro and In Vivo Techniques in Experimental Respirology

Pulmonary surfactant is present as the thin film of surface active material in the terminal airspaces and conducting airways. The major function of the surfactant film is to reduce the surface tension at the alveolar surface. Deficiency or dysfunction of pulmonary surfactant cause severe respiratory diseases that make the study of pulmonary surfactant not only of physiological but also of clinical importance.

There are three main categories of methods for assessing the properties of pulmonary surfactant: in vitro, in situ and in vivo techniques. Pulsating bubble surfactometer (PBS) and captive bubble surfactometer (CBS) enables to study surfactant properties at spherical air-liquid interphase. Capillary surfactometer in contrast to alveolar models mimics the human terminal airways and evaluates surface properties required for airway patency. Each of above-mentioned methods enables to study exogenous surfactants, as well as surface activity of lavage fluids or tracheal aspirates.

Biophysical characteristics should be reflected by lung compliance and, as a consequence, by improved blood oxygenation. Various animal models have been developed to evaluate the efficacy of surfactant replacement therapy on preterm and term animals. In vivo models can be divided in those, primarily involving surfactant deficiency, such as premature animal model, and those with secondary surfactant dysfunction or inactivation, such as meconium or acid aspiration models.

This review is restricted to the in vivo and in vitro techniques handled by the authors in their research performed within the last years at both domestic and external laboratories.
Anti-Inflammatory Drugs in the Treatment of Meconium Aspiration Syndrome
Authors: Mokra D. , Mokry J. , Calkovska A.
Published: June 2011

Anti-Inflammatory Drugs in the Treatment of Meconium Aspiration Syndrome

Meconium aspiration syndrome (MAS) is a major cause of respiratory distress in both the term and post-term neonates. Obstruction of the airways, dysfunction of pulmonary surfactant, inflammation, lung edema, pulmonary vasoconstriction and bronchoconstriction participate in the pathogenesis of this disorder. Since the inflammatory changes associated with meconium aspiration cause a severe impairment of the lung parenchyma including surfactant and influence the reactivity of both vascular and airway smooth muscle, administration of anti-inflammatory drugs may be of benefit also in the management of MAS. This article reviews effects of various anti-inflammatory drugs used in experimental models of MAS as well as in the treatment of newborns with meconium aspiration.
Quantification of Nonlinear Features in Cardiovascular Signals
Authors: Javorka M. , Tonhajzerova I. , Turianikova Z. , Chladekova L. , Javorka K. , Calkovska A.
Published: June 2011

Quantification of Nonlinear Features in Cardiovascular Signals

The analysis of spontaneous heart rate and blood pressure oscillations under standardized conditions is a rapid, sensitive, noninvasive and reproducible tool for the assessment of cardiovascular autonomic dysfunction. Since the heart and vessels are controlled by a nonlinear deterministic system, measures derived from nonlinear systems theory are increasingly used in cardiovascular variability analysis. New nonlinear methods with applicability to real biological signals are continuously developed to quantify new aspects of cardiovascular signals with the potential to reveal subtle changes in the cardiovascular control system. Nonlinear measures provide complementary information about qualitative features of the analyzed signal. Since the analysis of variability magnitude and signal nonlinear characteristics (complexity, recurrences, time irreversibility, etc.) can provide independent information on cardiovascular system control, we suggest that simultaneous use of both groups of measures can increase the information value and thus improve the sensitivity and reliability of the detection and monitoring of the cardiovascular system dysregulation during various pathological conditions.
Time Irreversibility of Heart Rate Oscillations During Orthostasis
Authors: Chladekova L. , Turianikova Z. , Tonhajzerova I. , Calkovska A. , Javorka M.
Published: June 2011

Time Irreversibility of Heart Rate Oscillations During Orthostasis

Introduction: Time irreversibility is a characteristic feature of non-equilibrium, complex systems involving cardiovascular control mediated by autonomic nervous system. Its analysis in heart rate variability (HRV) signal represents a new approach to assess cardiovascular regulatory mechanisms. The purpose of this paper was to assess the changes in various time irreversibility indices during the orthostatic test (a balance of autonomic nervous system shifted towards sympathetic predominance). In addition, we tested the behaviour of the selected irreversibility indices in relation to different lengths of analysed data and their mutual dependence.

Methods: We examined the irreversibility of HRV time series obtained from 28 healthy young subjects recorded during 20 minutes in the supine position followed by 15 minutes in the standing position. We used three different time irreversibility indices - Porta's, Guzik's and Costa's indices (P%, G% and A, respectively). The proposed irreversibility indices were derived from data segments containing 300, 600 and 1000 beat-to-beat intervals.

Results: Two of three time irreversibility indices (P% and A) were sensitive to the shift in sympathovagal balance during the orthostatic challenge even when calculated from the shortest data length. Indices were relatively insensitive to data length - there were no significant differences in relation to data length. Despite the difference in algorithms for the calculation of indices P% and A, these are closely mathematically related and do not provide mutually independent information.

Conclusion: We conclude that heart rate irreversibility indices are sensitive to the changes in autonomic tone after the orthostatic challenge even when derived from the 300 interbeat intervals. Porta's index seems to be more sensitive to autonomic nervous balance shift compared to Guzik's index. Costa's index is closely related to P% and do not provide any additional information compared to other indices.
Cardiac Vagal Control in Depression and Attention Deficit/Hyperactivity Disorder
Authors: Tonhajzerova I. , Ondrejka I. , Javorka K. , Calkovska A. , Javorka M.
Published: June 2011

Cardiac Vagal Control in Depression and Attention Deficit/Hyperactivity Disorder

The importance of the vagus nerve in the two way communication between the brain and the heart has been known for over 100 years. Recently, integrative theories that link central nervous system structures to cardiac vagal regulation, such as the polyvagal theory, have of late emerged. Based on the polyvagal theory, the respiratory sinus arrhythmia (as an index of cardiac vagal control) is considered as a psychophysiological marker of many aspects of behavioural functioning and emotion regulation in both children and adults. Although a lack of sensitive heart rate autonomic control likely reflects impaired cardiac nervous system regulation, the sophisticated brain-heart interactions are incompletely understood. Importantly, cardiac vagal dysregulation is associated with the increased risk of cardiovascular morbidity reflecting various pathophysiological states. Thus, we believe that the identifying of cardiac vagal control changes in mental disorders should represent an initial step towards the understanding of a potential pathomechanisms leading to later cardiac adverse outcomes; especially in children and adolescents.
A new snow thermodynamic scheme for large-scale sea-ice models
Authors: Lecomte Olivier , Fichefet Thierry , Vancoppenolle Martin , Nicolaus Marcel
Published: June 2011

This paper assesses the capabilities of a new one-dimensional snow scheme developed for the thermodynamic component of the Louvain-la-Neuve sea-Ice Model (LIM). the model is validated at Point Barrow, Alaska, and at Ice Station Polarstern (ISPOL) in the western Weddell Sea, Southern Ocean. the new snow thermodynamic scheme leads to better snow internal temperature profiles, with a set-up-dependent increase in the correlation between simulated and observed temperature profiles. on average over all runs, these correlations are 27% better with the six-layer configuration. the model’s ability to reproduce observed temperatures improves with the number of snow layers, but stabilizes after a threshold layer number is reached. the lowest and highest values for this threshold are 3 (at Point Barrow) and 6 (at ISPOL), respectively. Overall, the improvement of the model’s ability to simulate sea-ice thickness is not as significant as for snow temperature, probably because of the rather crude representation of the snow stratigraphy in the model.
Acceleration of sea-ice melting due to transmission of solar radiation through ponded ice area in the Arctic Ocean: results of in situ observations from icebreakers in 2006 and 2007
Authors: Itoh Motoyo , Inoue Jun , Shimada Koji , Zimmermann Sarah , Kikuchi Takashi , Hutchings Jennifer , McLaughlin Fiona , Carmack Eddy
Published: June 2011

Sea-ice melting processes were inferred from in situ sea-ice and ocean condition data obtained in the Arctic in summer 2006 and 2007. the relationship between ice concentration observed by on-board ice watches and water temperature showed negative correlations. This implies that as ice concentration decreases, the upper ocean becomes warmer due to greater absorption of solar radiation into open water, which promotes ice melting. However, heating of surface water is significant even in regions that were almost completely ice-covered, suggesting that transmitted solar radiation through the ice is also effective at melting sea ice. A simplified ice–upper-ocean coupled model was applied to examine the effect of heat input from open water, thick ice and thin ice. the ponded thin ice is estimated to transmit approximately three times more solar radiation than ponded thick ice. Model results suggest that transmission of solar radiation through ponded ice amplified the ice-albedo feedback mechanism, particularly in thin ice regions. Recently, the extent of old and thick multi-year ice in the Arctic Ocean has been rapidly reduced. As a result, heat input to the upper ocean through the ice is enhanced and ice melt is further accelerated.
Sea-ice drift characteristics revealed by measurement of acoustic Doppler current profiler and ice-profiling sonar off Hokkaido in the Sea of Okhotsk
Authors: Fukamachi Yasushi , Ohshima Kay I. , Mukai Yuji , Mizuta Genta , Wakatsuchi Masaaki
Published: June 2011

In the southwestern part of the Sea of Okhotsk off Hokkaido, sea-ice drift characteristics are investigated using the ice and water velocities obtained from a moored upward-looking acoustic Doppler current profiler (ADCP) during the winters of 1999–2001. Using hourly-mean values of these data along with the wind data measured at a nearby coastal station, the wind factor and turning angle of the relative velocity between the ice and water velocities with respect to the wind are calculated assuming free drift under various conditions. Since the simultaneous sea-ice draft data are also available from a moored ice-profiling sonar (IPS), we examine the dependence of drift characteristics on ice thickness for the first time. As ice thickness increases and wind decreases, the wind factor decreases and the turning angle increases, as predicted by the theory of free drift. This study clearly shows the utility of the moored ADCP measurement for studying sea-ice drift, especially with the simultaneous IPS measurement for ice thickness, which cannot be obtained by other methods.
Seasonal ice mass-balance buoys: adapting tools to the changing Arctic
Authors: Polashenski Chris , Perovich Don , Richter-Menge Jackie , Elder Bruce
Published: June 2011

Monitoring the local mass balance of Arctic sea ice provides opportunities to attribute the observed changes in a particular floe’s mass balance to specific forcing phenomena. A shift from multi-year to seasonal ice in large portions of the Arctic presents a challenge for the existing Lagrangian array of autonomous ice mass-balance buoys, which were designed with a perennial ice cover in mind. This work identifies the anticipated challenges of operation in seasonal ice and presents a new autonomous buoy designed to monitor ice mass balance in the seasonal ice zone. the new design presented incorporates features which allow the buoy to operate in thin ice and open water, and reduce its vulnerability to ice dynamics and wildlife damage, while enhancing ease of deployment. A test deployment undertaken from April to June 2009 is discussed and results are presented with analysis to illustrate both the features and limitations of the buoy’s abilities.
Sea-ice thickness variability in Storfjorden, Svalbard
Authors: Hendricks S. , Gerland S. , Smedsrud L.H. , Haas C. , Pfaffhuber A.A. , Nilsen F.
Published: June 2011

Results from electromagnetic induction surveys of sea-ice thickness in Storfjorden, Svalbard, reveal large interannual ice-thickness variations in a region which is typically characterized by a reoccurring polynya. the surveys were performed in March 2003, May 2006 and March 2007 with helicopter- and ship-based sensors. the thickness distributions are influenced by sea-ice and atmospheric boundary conditions 2 months prior to the surveys, which are assessed with synthetic aperture radar (SAR) images, regional QuikSCAT backscatter maps and wind information from the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis dataset. Locally formed thin ice from the Storfjorden polynya was frequently observed in 2003 and 2007 (mean thickness 0.55 and 0.37 m, respectively) because these years were characterized by prevailing northeasterly winds. In contrast, the entire fjord was covered with thick external sea ice in 2006 (mean thickness 2.21 m), when ice from the Barents Sea was driven into the fjord by predominantly southerly winds. the modal thickness of this external ice in 2006 increased from 1.2m in the northern fjord to 2.4 m in the southern fjord, indicating stronger deformation in the southern part. This dynamically thickened ice was even thicker than multi-year ice advected from the central Arctic Ocean in 2003 (mean thickness 1.83 m). the thermodynamic ice thickness of fast ice as boundary condition is investigated with a one-dimensional sea-ice growth model (1DICE) forced with meteorological data from the weather station at the island of Hopen, southeast of Storfjorden. the model results are in good agreement with the modal thicknesses of fast-ice measurements in all years.
Evaluation of a polynya flux model by means of thermal infrared satellite estimates
Authors: Krumpen Thomas , Willmes Sascha , Morales Maqueda Miguel Angel , Haas Christian , Hölemann Jens A. , Gerdes Rüdiger , Schröder David
Published: June 2011

We test the ability of a two-dimensional flux model to simulate polynya events with narrow open-water zones by comparing model results to ice-thickness and ice-production estimates derived from thermal infrared Moderate Resolution Imaging Spectroradiometer (MODIS) observations in conjunction with an atmospheric dataset. Given a polynya boundary and an atmospheric dataset, the model correctly reproduces the shape of an 11 day long event, using only a few simple conservation laws. Ice production is slightly overestimated by the model, owing to an underestimated ice thickness. We achieved best model results with the consolidation thickness parameterization developed by Biggs and others (2000). Observed regional discrepancies between model and satellite estimates might be a consequence of the missing representation of the dynamic of the thin-ice thickening (e.g. rafting). We conclude that this simplified polynya model is a valuable tool for studying polynya dynamics and estimating associated fluxes of single polynya events.
Characteristics of sea ice in the Okhotsk coastal polynyas revealed by satellites, ice-profiling sonar and digital camera observations
Authors: Nihashi Sohey , Ebuchi Naoto , Fukamachi Yasushi , Takahashi Shuhei
Published: June 2011

The characteristics of ice in the Okhotsk coastal polynyas are examined. A map of AMSR-E thin-ice thickness in the northwest shelf region shows that most of the coastal polynya area is covered by thin ice with a thickness of 0.1 m. the thickness increases sharply at the edge of the polynya. From comparisons with QuikSCAT backscatter, the thin-ice area corresponds well with the low-backscatter area during almost all the coastal polynya period. A comparison with ice thickness measured by an ice-profiling sonar in the coastal polynya region of northeastern Sakhalin shows a similar relationship, with the backscatter tending to be low when the ice is thin. the averaged backscatter of thin (≤0.1 m) ice is –19.6±2.8 dB (horizontal polarization). the backscatter of thin ice is considered to be mainly determined by the surface roughness because volume scattering of thin ice is low due to the dielectric properties associated with the high salinity. the results of this study suggest that the coastal polynya is covered with grease ice/nilas whose surface is almost mirror smooth. This is confirmed by a comparison with photographs taken at the coastal polynya region near Magadan, Russia. At the outer edge of the coastal polynya, a region of relatively high backscatter (>–16 dB) exists, probably because it has a rougher ice surface than the polynya area. This suggests that ice motion in this area may be convergent.
The interplay of dynamic and thermodynamic processes in driving the ice-edge location in the Southern Ocean
Authors: Stevens R.P. , Heil P.
Published: June 2011

A stand-alone sea-ice model (CICE4) was used to investigate the physical processes affecting the ice-edge location. Particular attention is paid to the relative contributions of dynamic and thermodynamic processes in advancing the ice edge equatorward during ice growth. Results from 10 years of an 11 year numerical simulation have been verified against satellite observations from 1998 to 2007. the autumn advance of the sea-ice edge is primarily due to thermodynamic processes, with significant dynamic contributions limited to regions such as 60–70˚ E and 310–340˚ E. In the dynamically dominated regions, winds with a southerly component cause equatorward ice advection but also induce thermodynamic growth of new ice, which occurs well poleward of the 15% ice-concentration contour where air temperature is lowest. As the ice moves into warmer water it melts, hence extending equatorward the region with ocean mixed layer at freezing point. This accelerates the northward progression of the ice edge and permits thermodynamic ice growth as soon as the air temperature reaches below the ocean freezing point. In regions where thermodynamic processes are dominant (e.g. 340–40˚ E), maximum ice production occurs just poleward of the 15% ice-concentration contour, where thin sea ice is prevalent. In these longitude bands, autumn ice melt is generally absent at the ice edge due to ineffective equatorward ice advection.
Laser altimetry sampling strategies over sea ice
Authors: Farrell Sinéad L. , Markus Thorsten , Kwok Ron , Connor Laurence
Published: June 2011

With the conclusion of the science phase of the Ice, Cloud and land Elevation Satellite (ICESat) mission in late 2009, and the planned launch of ICESat-2 in late 2015, NASA has recently established the IceBridge program to provide continuity between missions. A major goal of IceBridge is to obtain a sea-ice thickness time series via airborne surveys over the Arctic and Southern Oceans. Typically two laser altimeters, the Airborne Topographic Mapper (ATM) and the Land, Vegetation and Ice Sensor (LVIS), are utilized during IceBridge flights. Using laser altimetry simulations of conventional analogue systems such as ICESat, LVIS and ATM, with the multi-beam system proposed for ICESat-2, we investigate differences in measurements gathered at varying spatial resolutions and the impact on sea-ice freeboard. We assess the ability of each system to reproduce the elevation distributions of two sea-ice models and discuss potential biases in lead detection and sea-surface elevation, arising from variable footprint size and spacing. The conventional systems accurately reproduce mean freeboard over 25 km length scales, while ICESat-2 offers considerable improvements over its predecessor ICESat. In particular, its dense along-track sampling of the surface will allow flexibility in the algorithmic approaches taken to optimize the signal-to-noise ratio for accurate and precise freeboard retrieval.
Summer Antarctic sea ice as seen by ASAR and AMSR-E and observed during two IPY field cruises: a case study
Authors: Tekeli Ahmet E. , Kern Stefan , Ackley Stephen F. , Ozsoy-Cicek Burcu , Xie Hongjie
Published: June 2011

Envisat Advanced Synthetic Aperture Radar (ASAR) Wide Swath Mode (WSM) images are used to derive C-band HH-polarization normalized radar cross sections (NRCS). These are compared with ice-core analysis and visual ship-based observations of snow and ice properties observed according to the Antarctic Sea Ice Processes and Climate (ASPeCt) protocol during two International Polar Year summer cruises (Oden 2008 and Palmer 2009) in West Antarctica. Thick first-year (TFY) and multi-year (MY) ice were the dominant ice types. the NRCS value ranges between –16.3 ± 1.1 and –7.6 ± 1.0 dB for TFY ice, and is –12.6 ± 1.3 dB for MY ice; for TFY ice, NRCS values increase from –~15 dB to –9 dB from December/January to mid-February. In situ and ASPeCt observations are not, however, detailed enough to interpret the observed NRCS change over time. Co-located Advanced Microwave Scanning Radiometer–Earth Observing System (AMSR-E) vertically polarized 37 GHz brightness temperatures (TB37V), 7 day and 1 day averages as well as the TB37V difference between ascending and descending AMSR-E overpasses suggest the low NRCS values (–15 dB) are associated with snowmelt being still in progress, while the change towards higher NRCS values (–9 dB) is caused by commencement of melt– refreeze cycles after about mid-January.
Cross-borehole resistivity tomography of Arctic and Antarctic sea ice
Authors: Jones Keleigh , Ingham Malcolm , Pringle Daniel , Eicken Hajo
Published: June 2011

As an inhomogeneous mixture of pure ice, brine, air and solid salts the physical properties of sea ice depend on its highly temperature-dependent microstructure. Understanding the microstructure and the way it responds to variations in temperature and salinity is crucial in developing an improved understanding of the interaction between sea ice and the environment. However, measurements monitoring the internal structure of sea ice are difficult to obtain without disturbing its natural state. We have recently developed an application of cross-borehole d.c. resistivity tomography to make in situ measurements that resolve the anisotropic resistivity structure of first-year sea ice. We present results from measurements made in 2008 off Barrow, Alaska, and in 2009 off Ross Island, Antarctica. the sea ice in these two regions forms in different environments: at Barrow, relatively quiescent conditions typically lead to a predominance of columnar ice, while more turbulent conditions and underwater ice formation in McMurdo Sound tend to produce a larger component of frazil or platelet ice. Interpretation of the resistivity measurements carried out in association with temperature and salinity data collected simultaneously allows both observation of the temporal evolution of the ice structure and, in the case of the Antarctic measurements, the identification of different ice types.
Retrieval of sea-ice thickness distribution in the Sea of Okhotsk from ALOS/PALSAR backscatter data
Authors: Toyota Takenobu , Ono Shuji , Cho Kohei , Ohshima Kay I.
Published: June 2011

Although satellite data are useful for obtaining ice-thickness distribution for perennial sea ice or in stable thin-sea-ice areas, they are still largely an unresolved issue for the seasonal ice zone (SIZ). We address this problem using L-band synthetic aperture radar (SAR). In the SIZ, ice-thickness growth is closely related to deformation, so surface roughness is expected to correlate with ice thickness. L-band SAR, suitable for detecting such surface roughness, is a promising tool for obtaining thickness distribution. This idea was supported by an airborne polarimetric and interferometric SAR (Pi-SAR) validation. To extend this result to spaceborne L-band SAR with coarser resolution, we conducted in situ measurements of ice thickness and surface roughness in February 2008 in the southern Sea of Okhotsk with an icebreaker in coordination with the Advanced Land Observing Satellite (ALOS)/Phased Array-type L-band SAR (PALSAR) orbit. A helicopter-borne laser profiler was used to improve the estimation of surface roughness. It was found that backscatter coefficients (HH) correlated well with ice thickness (R = 0.86) and surface roughness (R = 0.70), which confirms the possibility of determining ice-thickness distribution in the SIZ. the interannual variation of PALSAR-derived ice-thickness distribution in the southern Sea of Okhotsk is also discussed.
Spatial and temporal characterization of sea-ice deformation
Authors: Hutchings Jennifer K. , Roberts Andrew , Geiger Cathleen A. , Richter-Menge Jacqueline
Published: June 2011

In late March 2007 an array of GPS ice drifters was deployed in the Beaufort Sea as part of the Sea Ice Experiment: Dynamic Nature of the Arctic (SEDNA). the drifters were deployed in an array designed to resolve four, nested spatial scales of sea-ice deformation, from 10 to 140 km, with the arrays maintaining appropriate shape for strain-rate calculation until mid-June. In this paper, we test whether sea-ice deformation displays fractal properties in the vicinity of SEDNA. We identify that deformation time series have different spectral properties depending on the spatial scale. At the scales around 100 km, deformation is a red-noise process, indicating the importance of the ice-pack surface forcing in determining the deformation rate of sea ice at this scale. At smaller scales, the deformation becomes an increasingly whiter process (it has pink noise properties), which suggests an increasing role of dissipative processes at smaller scales. At spatial scales of 10–100 km, and sub-daily scales, there is no deformation coherence across scales; coherence only becomes apparent at longer scales greater than 100 km. the lack of coherence at small scales aids in understanding previous observations where correlation between 10km regions adjacent to each other varied widely, with correlation coefficients between –0.3 and 1. This suggests it is not appropriate to think of sea ice as having a decorrelation length scale for deformation. We find that lead scale observations of deformation are required when estimating ice growth in leads and ridging time series. For the two SEDNA arrays, we find coherence between 140 and 20 km scale deformation up to periods of 16 days. This suggests sea-ice deformation displays coherent deformation between 100 km scale and the scale of the Beaufort Sea (of order 1000 km), over synoptic time periods (daily to weekly timescales). Organization of leads at synoptic and larger scales is an emergent feature of the deformation field that is caused by the smooth variation of surface forcing (wind) on the ice pack.