bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effectiveness and Efficacy of an Intensive Cardiac Rehabilitation Program in 24 Sites
Authors: Silberman Anna , Banthia Rajni , Estay Ivette S. , Kemp Colleen , Studley Joli , Hareras Dennis , Ornish Dean
Published: June 2010

Purpose.

The purpose of this study is to test the efficacy and effectiveness of an intensive cardiac rehabilitation program in improving health outcomes in multiple sites.

Methods.

This study employs a nonexperimental (prospective time series) design to investigate changes in cardiovascular disease in 2974 men and women from 24 socioeconomically diverse sites who participated in an intensive cardiac rehabilitation program at baseline, 12 weeks, and 1 year. Paired t-tests were used to assess differences by comparing baseline values to those after 12 weeks, baseline values to those after 1 year, and values after 12 weeks to those after 1 year.

Results.

Eighty-eight percent of patients remained enrolled in the program after 12 weeks, and 78.1% remained enrolled in the program after 1 year. Patients showed statistically significant improvements after 12 weeks in body mass index (BMI), triglycerides, low density lipoprotein cholesterol, total cholesterol, hemoglobin A1c, systolic blood pressure, diastolic blood pressure, depression, hostility, exercise, and functional capacity. These differences also remained significant after 1 year. There was additional significant improvement between 12 weeks and 1 year only in BMI, high density lipoprotein cholesterol, functional capacity, and hostility, and significant recidivism between 12 weeks and 1 year in all other measures (except triglycerides) and depression, yet improvements from baseline to 1 year remained significant in all measures (except HDL, which was unchanged) (p < .005).

Conclusions.

This intensive cardiac rehabilitation program was feasible and sustainable for most patients who enrolled and was associated with numerous subjective and objective improvements in health outcomes. It demonstrates that the intervention works when it is administered by staff at multiple clinical/community sites in four different states. These improvements were also seen in patients 65 years of age or older.
Milk production of pseudopregnant multiparous does.
Authors: Szendrő  Zs. , Matics Zs. , Brecchia G. , Theau-Clément M. , Nagy Z. , Princz Z. , Biró-Németh E. , Radnai I. , Nagy I.
Published: June 2010

The aim of the experiment was to evaluate the milk production of pseudopregnant does. In this experiment, data of multiparous, inseminated, pregnant (IP, n=15) does and two groups of presumably pseudopregnant multiparous does: inseminated, non-pregnant (INP, n=17) and induced to ovulation by GnRH (1.5 μg per animal) at the day of insemination (11 d after parturition) (non-inseminated, ovulating: NIO, n=15) were analysed. The progesterone level was measured at the 12th d after treatment to determine if females were pseudopregnant. All IP and NIO does were pregnant and pseudopregnant, respectively. Within the INP group, 10 and 7 does were diagnosed as positive (INPO) or negative (INPNO) for pseudopregnancy. Two of the INPNO does perished during lactation. The average milk production of groups IP, INP and NIO was 212, 92 and 72 g/d, respectively (P<0.001). The proportion of rabbit does reaching daily milk yields of <10, 10-50, 50-100, 100-160, >160 g in the various groups were: IP=0, 0, 0, 0 and 100%, NIO=20, 13, 27, 40 and 0%, INP=15, 15, 15, 55 and 0%, respectively. The daily milk yield of the 5 INPNO does was 2, 6, 27, 84 and 139 g, respectively. These results demonstrated that multiparous empty does, pseudopregnant or non-pseudopregnant, can produce milk, but in lower quantities than multiparous does after kindling.
Descriptive characterization of a nigerian heterogeneous rabbit population - factors affecting litter traits.
Authors: Oseni S.O. , Ajayi B.A.
Published: June 2010

Thi study evaluated the effect of female body weight at conception (FWC), season of mating (SM), type of mating (TM) and litter size at birth (LSB) on the litter performance in a heterogeneous Nigerian population of rabbits. Data on 116 litters from 10 bucks and 48 does across three parities were analysed. Reproductive traits evaluated included LSB, number born alive (NBA), litter sizes and weights at 7, 14 and 21 d post-kindling, pre-weaning survival rate (SR) and daily weight gain of kits from kindling to weaning (DWG). A fi xed linear model that included FWC (light and heavy does), TM (homospermic and heterospermic matings), LSB classes (low, medium and large) and SM (rainy or dry) was used. Results showed that heavier does at concenption showed higher performance for LSB and NBA (P<0.05) than lighter does. Average weight of kits at kindling and at 28 d, as well as kit SR and DWG, were signifi cantly higher in low-sized litters, when compared with intermediate- and large-sized litters (P<0.05). LSB, NBA and litter size at weaning were higher in litters produced by heterospermically mated does compared with homospermically mated does. Season of mating affected LSB and NBA (P<0.05), being signifi cantly larger the litters in the rainy season.
Variability of the nighttime OH layer and mesospheric ozone at high latitudes during northern winter: influence of meteorology
Authors: Damiani A. , Storini M. , Santee M. L. , Wang S.
Published: June 2010

Abstract. Analyses of OH zonal means, recorded at boreal high latitudes by the Aura Microwave Limb Sounder (MLS), have shown medium- (weeks) and short-term (days) variability of the nighttime OH layer. Because of the exceptional descent of air from the mesosphere-lower thermosphere region, medium-term variability occurred during February 2006 and February/March 2009. The layer normally situated at about 82 km descended by about 5–7 km, and its density increased to more than twice January values. In these periods and location the abundance of the lowered OH layer is comparable with the OH values induced by Solar Energetic Particle (SEP) forcing (e.g. SEP events of January 2005) at the same altitudes. In both years, the drop of the OH layer was coupled with increased mesospheric temperatures, elevated carbon monoxide and an almost complete disappearance of ozone at the altitude of the descended layer (which was not observed in other years). Moreover, under these exceptional atmospheric conditions, the third ozone peak is shown descending to lower altitude and increasing its abundance, with maximum values recorded during February 2009. Short-term variability occurred during Sudden Stratospheric Warming (SSW) events, in particular in January 2006, February 2008 and January 2009, when dynamics led to a smaller abundance of the OH layer at its typical altitude. The upward extension of the OH layer coupled to changes in ozone and carbon monoxide is shown to be strongest during the SSW of January 2009, coincident with the lowest upper mesospheric temperatures recorded at that time of year during 2005–2009. Finally, the series of SSW events that occurred in late January/February 2008 induced noticeable short-term variability in ozone at altitudes of both the ozone minimum and the third ozone peak. These phenomena, confined inside the polar vortex, are an additional tool that can be used to investigate mesospheric vortex dynamics.
Variation of particle number size distributions and chemical compositions at the urban and downwind regional sites in the Pearl River Delta during summertime pollution episodes
Authors: Yue D. L. , Hu M. , Wu Z. J. , Guo S. , Wen M. T. , Nowak A. , Wehner B. , Wiedensohler A. , Takegawa N. , Kondo Y. , Wang X. S. , Li Y. P. , Zeng L. M. , Zhang Y. H.
Published: June 2010

Abstract. In order to characterize the features of particulate pollution in the Pearl River Delta (PRD) in the summer, continuous measurements of particle number size distributions and chemical compositions were simultaneously performed at Guangzhou urban site (GZ) and Back-garden downwind regional site (BG) in July 2006. Particle number concentration from 20 nm to 10 μm at BG was (1.7±0.8)×104 cm−3, about 40% lower than that at GZ, (2.9±1.1)×104 cm−3 with intensive traffic emissions. The total particle volume concentration at BG was 94±34 μm3 cm−3, similar to that at GZ, 96±43 μm3 cm−3. More 20–100 nm particles, significantly affected by the traffic emissions, were observed at GZ, while 100–660 nm particle number concentrations were similar at both sites as they are more regional. PM2.5 values were also similar at GZ (69±43 μg m−3) and BG (69±58 μg m−3), indicating the fine particulate pollution in the PRD region to be regional. Two kinds of pollution episodes, the accumulation pollution episode and the regional transport pollution episode, were observed. Fine particles over 100 nm dominated both number and volume concentrations of total particles during the late periods of these pollution episodes. Accumulation and secondary transformations are two main reasons for the nighttime accumulation pollution episode. SO4−2, NO3−, and NH4+ accounted for about 60% in 100–660 nm particle mass and PM2.5. When south or south-southeast wind prevailed in the PRD region, regional transport of pollutants takes place. Regional transport contributed about 30% to fine particulate pollution at BG during a regional transport case. Secondary transformation played an important role during regional transport, causing higher increase rates of secondary ions in PM1.0 than other species and shifting the peaks of sulfate and ammonium mass size distributions to larger sizes. SO4−2, NO3−, and NH4+ accounted for about 70% and 40% of PM1.0 and PM2.5, respectively.
Turbulence characteristics in the tropical mesosphere as obtained by MST radar at Gadanki (13.5° N, 79.2° E)
Authors: Sasi M. N. , Vijayan L.
Published: June 2010

Abstract. Turbulent kinetic energy dissipation rates (ε) and eddy diffusion coefficients (Kz) in the tropical mesosphere over Gadanki (13.5° N, 79.2° E), estimated from Doppler widths of MST radar echoes (vertical beam), observed over a 3-year period, show a seasonal variation with a dominant summer maximum. The observed seasonal variation of ε and Kz in the mesosphere is only partially consistent with that of gravity wave activity inferred from mesospheric winds and temperatures measured by rockets for a period of 9 years at Trivandrum (8.5° N, 77° E) (which shows two equinox and one summer maxima) lying close to Gadanki. The summer maximum of mesospheric ε and Kz values appears to be related to the enhanced gravity wave activity over the low-latitude Indian subcontinent during the southwest monsoon period (June – September). Both ε and Kz in the mesosphere over Gadanki show an increase with an increase in height during all seasons. The absolute values of observed ε and Kz in the mesosphere (above ~80 km) does not show significant differences from those reported for high latitudes. Comparison of observed Kz values during the winter above Gadanki with those over Arecibo (18.5° N, 66° W) shows that they are not significantly different from each other above the ~80 km altitude.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; tropical meteorology; wave and tides)
Evidence of transport, sedimentation and coagulation mechanisms in the relaxation of post-volcanic stratospheric aerosols
Authors: Fussen D. , Vanhellemont F. , Bingen C.
Published: June 2010

Abstract. Spatio-temporal distributions of stratospheric aerosols, measured by the ORA instrument from August 1992 until May 1993, are presented in the latitude range (40° S–40° N). Particle total number density, mode radius and distribution width are derived and interpreted. The respective roles of advection, sedimentation and coagulation are discussed. We also identify clear transport/sedimentation patterns and we show the enhancement of coagulation in stagnation regions. Efficient transport of aerosol particles up to 50 km is suggested.Key words. Atmospheric composition and structure (aerosols and particles; middle atmosphere-composition and chemistry; volcanic effects)
The Cluster Magnetic Field Investigation: overview of in-flight performance and initial results
Authors: Balogh A. , Carr C. M. , Acuña M. H. , Dunlop M. W. , Beek T. J. , Brown P. , Fornacon K.-H. , Georgescu E. , Glassmeier K.-H. , Harris J. , Musmann G. , Oddy T. , Schwingenschuh K.
Published: June 2010

Abstract. The accurate measurement of the magnetic field along the orbits of the four Cluster spacecraft is a primary objective of the mission. The magnetic field is a key constituent of the plasma in and around the magnetosphere, and it plays an active role in all physical processes that define the structure and dynamics of magnetospheric phenomena on all scales. With the four-point measurements on Cluster, it has become possible to study the three-dimensional aspects of space plasma phenomena on scales commeasurable with the size of the spacecraft constellation, and to distinguish temporal and spatial dependences of small-scale processes. We present an overview of the instrumentation used to measure the magnetic field on the four Cluster spacecraft and an overview the performance of the operational modes used in flight. We also report on the results of the preliminary in-orbit calibration of the magnetometers; these results show that all components of the magnetic field are measured with an accuracy approaching 0.1 nT. Further data analysis is expected to bring an even more accurate determination of the calibration parameters. Several examples of the capabilities of the investigation are presented from the commissioning phase of the mission, and from the different regions visited by the spacecraft to date: the tail current sheet, the dusk side magnetopause and magnetosheath, the bow shock and the cusp. We also describe the data processing flow and the implementation of data distribution to other Cluster investigations and to the scientific community in general.Key words. Interplanetary physics (instruments and techniques) – magnetospheric physics (magnetospheric configuration and dynamics) – space plasma physics (shock waves)
Compressional Pc5 type pulsations in the morningside plasma sheet
Authors: Vaivads A. , Baumjohann W. , Haerendel G. , Nakamura R. , Kucharek H. , Klecker B. , Lessard M. R. , Kistler L. M. , Mukai T. , Nishida A.
Published: June 2010

Abstract. We study compressional pulsations in Pc5 frequency range observed in the dawn-side at distances of about 10 RE , close to the magnetic equator. We use data obtained during two events of conjunctions between Equator-S and Geotail: 1000–1700 UT on 9 March 1998, and 0200–0600 UT on 25 April 1998. In both events, pulsations are observed after substorm activity. The pulsations are antisymmetric with respect to the equatorial plane (even mode), and move eastward with phase velocity close to plasma velocity. The pulsations tend to be pressure balanced. We also discuss possible generation mechanisms of the pulsations.Key words. Magnetospheric physics (magnetospheric configuration and dynamics; MHD waves and instabilities; plasma sheet)
Magnetospheric response to the solar wind as indicated by the cross-polar potential drop and the low-latitude asymmetric disturbance field
Authors: Eriksson S. , Blomberg L. G. , Ivchenko N. , Karlsson T. , Marklund G. T.
Published: June 2010

Abstract. The cross-polar potential drop Φpc and the low-latitude asymmetric geomagnetic disturbance field, as indicated by the mid-latitude ASY-H magnetic index, are used to study the average magnetospheric response to the solar wind forcing for southward interplanetary magnetic field conditions. The state of the solar wind is monitored by the ACE spacecraft and the ionospheric convection is measured by the double probe electric field instrument on the Astrid-2 satellite. The solar wind-magnetosphere coupling is examined for 77 cases in February and from mid-May to mid-June 1999 by using the interplanetary magnetic field Bz component and the reconnection electric field. Our results show that the maximum correlation between Φpc  and the reconnection electric field is obtained approximately 25 min after the solar wind has reached a distance of 11 RE from the Earth, which is the assumed average position of the magnetopause. The corresponding correlation for ASY-H shows two separate responses to the reconnection electric field, delayed by about 35 and 65 min, respectively. We suggest that the combination of the occurrence of a large magnetic storm on 18 February 1999 and the enhanced level of geomagnetic activity which peaks at Kp = 7- may explain the fast direct response of ASY-H to the solar wind at 35 min, as well as the lack of any clear secondary responses of Φpc  to the driving solar wind at time delays longer than 25 min.Key words. Magnetospheric physics (solar wind-magnetosphere interactions; plasma convection) – Ionosphere (electric fields and currents)
Characteristics of episodes with extremely low ozone values in the northern middle latitudes 1957−2000
Authors: Bojkov R. D. , Balis D. S.
Published: June 2010

Abstract. A number of episodes are observed when the total ozone for 2 to 3 days has fallen below 220 matm-cm in the northern mid- and polar latitudes in autumn. The occurrences of such episodes represent ozone deviations of about one-third from the pre-1976 Oct-Nov-Dec monthly mean! By using primarily quality checked Dobson data, a clear identification was made of more than three dozen short spells with extremely low ozone in the 1957–1978 period. In the following twenty-two years (1979–2000), using mainly TOMS data, one can identify ~ 46 cases with ozone values falling below 220 matm-cm for longer than 1 day, with each time over an area greater than 500,000 km2 . The Ozone Mass Deficiency (O3MD) from the pre-1976 average ozone values over the affected area was ~2.8 Mt per day, i.e. four to seven times greater than it would be, assuming only a long-term trend in the Oct-Nov-Dec period. The Extremely Low Ozone (ELO3) events on the day of their appearance over the N. Atlantic/European region contribute to the O3MD by representing 16% of the deficiency due to the Oct-Nov trend in the entire 40–65° N latitudinal belt. The O3MD of the greater pool with low ozone (here taken as <260 matm-cm) surrounding the area of the lowest events could contribute on the day of their appearance in Oct-Nov up to 60% and in December, ~30% to the deficiency due to the trend over the entire 40–65° N belt. Analysis of synoptic charts, supported by a backward trajectory on the isentropic surfaces 350 and 380 K, shows that in most of the events, subtropical air masses with low ozone content were transported from the Atlantic toward the UK, Scandinavia, and in many cases, further to the western sub-polar regions of Russia. This transport was sometimes combined with upward motions above a tropospheric anticyclone which lifted low ozone mixing ratios to higher altitudes. The ELO3 events cause a significant deficiency above the tropopause where, in general, the subtropical air is injected. In fact, the overall amount of ozone is not depleted, but redistributed on the hemispheric scale. Review of low ozone events, defined as days with negative deviations from the pre-1976 averages greater than 25% show, in general, similar origin. The seasonally averaged area with ELO3 and the associated O3MD, as well as for the cases with deviations > –25%, has increased during the 1990s, which could be an indication of stronger and/or more frequent subtropical air intrusions. Their occurrences could contribute noticeably to the ozone deficiency of the middle latitude ozone during the days of ELO3 appearances; however, their contribution to the long-term trend of the ozone seasonal decline is of the order of ~10%.Key words. Atmospheric composition and structure (middle atmosphere - composition and chemistry) Meteorology and atmospheric dynamics (middle atmosphere dynamics)
Plasma and wave phenomena induced by neutral gas releases in the solar wind
Authors: Laakso H. , Grard R. , Janhunen P. , Trotignon J.-G.
Published: June 2010

Abstract. We investigate plasma and wave disturbances generated by nitrogen (N2) gas releases from the cooling system of an IR-camera on board the Vega 1 and Vega 2 spacecraft, during their flybys of comet Halley in March 1986. N2 molecules are ionized by solar UV radiation at a rate of ~ 7 · 10-7 s-1 and give rise to a plasma cloud expanding around the spacecraft. Strong disturbances due to the interaction of the solar wind with the N+2 ion cloud are observed with a plasma and wave experiment (APV-V instrument). Three gas releases are accompanied by increases in cold electron density and simultaneous decreases of the spacecraft potential; this study shows that the spacecraft potential can be monitored with a reference sensor mounted on a short boom. The comparison between the model and observations suggests that the gas expands as an exhaust plume, and approximately only 1% of the ions can escape the beam within the first meters. The releases are also associated with significant increases in wave electric field emission (8 Hz–300 kHz); this phenomenon lasts for more than one hour after the end of the release, which is most likely due to the temporary contamination of the spacecraft surface by nitrogen gas. DC electric fields associated with the events are complex but interesting. No magnetic field perturbations are detected, suggesting that no significant diamagnetic effect (i.e. magnetic cavity) is associated with these events.Key words. Ionosphere (planetary ionosphere) – Space plasma physics (active perturbation experiments; instruments and techniques)
OVATION: Oval variation, assessment, tracking, intensity, and online nowcasting
Authors: Newell P. T. , Sotirelis T. , Ruohoniemi J. M. , Carbary J. F. , Liou K. , Skura J. P. , Meng C.-I. , Deehr C. , Wilkinson D. , Rich F. J.
Published: June 2010

Abstract. The location of the auroral oval and the intensity of the auroral precipitation within it are basic elements in any adequate characterization of the state of the magnetosphere. Yet despite the many ground-based and spacecraft-borne instruments monitoring various aspects of auroral behavior, there are no clear and consistent answers available to those wishing to locate the auroral oval or to quantify its intensity. The purpose of OVATION is to create a tool which does so. OVATION is useful both for archival purposes and for space weather nowcasting. The long-running DMSP particle data set, which covers both hemispheres, and has operated since the early 1980s, and which will continue to operate well into the next decade, is chosen as a calibration standard. Other data sets, including global images from Polar UVI, SuperDARN boundaries, and meridian scanning photometer images, are cross-calibrated to the DMSP standard. Each incorporated instrument has its average offset from the DMSP standard determined as a function of MLT, along with the standard deviations. The various data can, therefore, be combined in a meaningful manner, with the weight attached to a given boundary measurement varying inversely with the variance (square of the standard deviation). OVATION currently spans from December 1983 through the present, including real-time data. Participation of additional experimenters is highly welcomed. The only prerequisites are a willingness to conduct the prescribed cross-calibration procedure, and to make the data available online. The real-time auroral oval location can be found here: http://sd-www.jhuapl.edu/Aurora/ovation live/northdisplay.html.Key words. Magnetospheric physics (auroral phenomena; energetic particles, precipitating; magnetosphere – ionosphere interactions)
A model of mid-latitude E-region plasma convergence inside a planetary wave cyclonic vortex
Authors: Shalimov S. , Haldoupis C.
Published: June 2010

Abstract. Recently, Shalimov et al. (1999) proposed a new mechanism for large-scale accumulation of long-lived metallic ions in the mid-latitude ionosphere driven by planetary waves in the lower thermosphere. In this mechanism, the combined action of frictional and horizontal magnetic field forces at E-region altitudes causes the plasma to converge and accumulate in large areas of positive neutral wind vorticity within a propagating planetary wave. The present paper provides a theoretical formulation for this mechanism by modelling both horizontal and vertical plasma transport effects within a planetary wave vortex, of cyclonic neutral wind. Non-steady-state numerical solutions of the ion continuity equation show that the proposed accumulation process can enhance the ionization significantly inside the planetary wave vortex but its efficiency depends strongly on altitude, whereas on the other hand, it can be complicated by vertical plasma motions. The latter, which are driven by the same planetary wave wind field under the action of the vertical Lorentz force and meridional wind forcing along the magnetic field lines, can lead to either plasma compressions or depletions, depending on the prevailing wind direction. We conclude that, for shorter times, vertical plasma transport may act constructively to the horizontal gathering process to produce considerable E-region plasma accumulation over large sectors of a planetary wave vortex of cyclonic winds.Key words. Ionosphere (ionosphere-atmosphere interactions; mid-latitude ionosphere; sporadic E-layers) – Meteorology and atmospheric dynamics (waves and tides)
Estimation of the characteristic energy of electron precipitation
Authors: del Pozo C. F. , Kosch M. J. , Honary F.
Published: June 2010

Abstract. Data from simultaneous observations (on 13 February 1996, 9 November 1998, and 12 February 1999) with the IRIS, DASI and EISCAT systems are employed in the study of the energy distribution of the electron precipitation during substorm activity. The estimation of the characteristic energy of the electron precipitation over the common field of view of IRIS and DASI is discussed. In particular, we look closely at the physical basis of the correspondence between the characteristic energy, the flux-averaged energy, as defined below, and the logarithm of the ratio of the green-light intensity to the square of absorption. This study expands and corrects results presented in the paper by Kosch et al. (2001). It is noticed, moreover, that acceleration associated with diffusion processes in the magnetosphere long before precipitation may be controlling the shape of the energy spectrum. We propose and test a "mixed" distribution for the energy-flux spectrum, exponential at the lower energies and Maxwellian or modified power-law at the higher energies, with a threshold energy separating these two regimes. The energy-flux spectrum at Tromsø, in the 1–320 keV range, is derived from EISCAT electron density profiles in the 70–140 km altitude range and is applied in the "calibration" of the optical intensity and absorption distributions, in order to extrapolate the flux and characteristic energy maps.Key words. Ionosphere (auroral ionosphere; particle precipitation; particle acceleration)
Cluster magnetic field observations at a quasi-parallel bow shock
Authors: Lucek E. A. , Horbury T. S. , Dunlop M. W. , Cargill P. J. , Schwartz S. J. , Balogh A. , Brown P. , Carr C. , Fornacon K.-H. , Georgescu E.
Published: June 2010

Abstract. We present four-point Cluster magnetic field data from a quasi-parallel shock crossing which allows us to probe the three-dimensional structure of this type of shock for the first time. We find that steepened ULF waves typically have a scale larger than the spacecraft separation ( ~ 400–1000 km), while SLAMS-like magnetic field enhancements have different signatures in | B | at the four spacecraft, suggesting that they have a smaller scale size. In the latter case, however, the angular variations of B are similar, consistent with the space-craft making different trajectories through the same structure. The field enhancements have different orientations relative to a model bow shock normal, which might arise from different degrees of deceleration and deflection of the surrounding solar wind plasma. The observed rotation of the magnetic field rising from a direction approximately parallel to the model bow shock normal to a direction more perpendicular to the model normal across the field enhancement is consistent with previously published results. Successive magnetic field enhancements or ULF waves, and the leading and trailing edges of the same structure, are found to have different orientations.Key words. Interplanetary physics (planetary bow shocks)
A Statistical study of the Doppler spectral width of high-latitude ionospheric F-region echoes recorded with SuperDARN coherent HF radars
Authors: Villain J.-P. , André R. , Pinnock M. , Greenwald R. A. , Hanuise C.
Published: June 2010

Abstract. The HF radars of the Super Dual Auroral Radar Network (SuperDARN) provide measurements of the E × B drift of ionospheric plasma over extended regions of the high-latitude ionosphere. We have conducted a statistical study of the associated Doppler spectral width of ionospheric F-region echoes. The study has been conducted with all available radars from the Northern Hemisphere for 2 specific periods of time. Period 1 corresponds to the winter months of 1994, while period 2 covers October 1996 to March 1997. The distributions of data points and average spectral width are presented as a function of Magnetic Latitude and Magnetic Local Time. The databases are very consistent and exhibit the same features. The most stringent features are: a region of very high spectral width, collocated with the ionospheric LLBL/cusp/mantle region; an oval shaped region of high spectral width, whose equator-ward boundary matches the poleward limit of the Holzworth and Meng auroral oval. A simulation has been conducted to evaluate the geometrical and instrumental effects on the spectral width. It shows that these effects cannot account for the observed spectral features. It is then concluded that these specific spectral width characteristics are the signature of ionospheric/magnetospheric coupling phenomena.Key words. Ionosphere (auroral ionosphere; ionosphere-magnetosphere interactions; ionospheric irregularities)
The 16-day variation in tidal amplitudes at Grahamstown (33.3° S, 26.5° E)
Authors: Malinga S. B. , Poole L. M. G.
Published: June 2010

Abstract. Meteor wind data at Grahamstown (33.3° S, 26.5° E) have been used to study the short-term (planetary scale) variations of the diurnal and semidiurnal tidal amplitudes at ~ 90 km altitude. Wavelet multi-resolution and spectral techniques reveal that planetary periodicities of ~ 10 and ~ 16 days dominate the wave spectrum in the ~ 2–20-day period range. The quasi-16-day oscillation is thought to be related to similar oscillations in the lower atmosphere. Also, there seems to be a link between the winter/equinox 16-day oscillation in the mean flow and that in the semidiurnal tidal amplitudes. It is thought that this is probably due to either the coupling between the normal mode-mean flow interactions and the gravity wave-tidal interactions, or to direct nonlinear interactions between planetary waves and the tide. On the other hand, a comparison of the mean flow and the diurnal tide does not show evidence of correlation. Possible reasons for this disparity are discussed briefly.Key words. Meteorology and atmospheric dynamics (waves and tides)
An explanation for some fallstreak clouds
Authors: Worthington R. M.
Published: June 2010

Abstract. Fallstreak cirrus clouds are associated with super-saturated air, together with waves, instabilities and/or turbulence; however, their precise cause is usually uncertain. This paper uses already-published satellite, radiosonde and radar data, reanalysed to study some large fallstreaks which had been previously overlooked. The fallstreaks – up to 60 km long with a parent cloud 20 km wide – are caused by lifting and/or turbulence from a mountain wave, rather than, for example, Kelvin-Helmholtz instabilities. If turbulent breaking of mountain waves affects ice particle formation, this may be relevant for the seeder-feeder effect on orographic rain, and the efficiency of mountain-wave polar stratospheric clouds for ozone depletion.Key words. Meteorology and atmospheric dynamics (turbulence; waves and tides) – Atmospheric composition and structure (cloud physics and chemistry)
Interhemispheric comparison of spectral width boundary as observed by SuperDARN radars
Authors: Hosokawa K. , Woodfield E. E. , Lester M. , Milan S. E. , Sato N. , Yukimatu A. S. , Iyemori T.
Published: June 2010

Abstract. Previous studies have shown that dayside equatorward edge of coherent HF radar backscatter having broad Doppler spectral width is coincident with the equatorward edge of the cusp particle precipitation. This enables the boundary between broad and narrow spectral width backscatters (spectral width boundary) in the dayside magnetic local time sector to be used as a proxy for the open/closed field line boundary. The present case study employs magnetically conjugate SuperDARN coherent HF radars to make an inter-hemispheric comparison of the location and variation of the spectral width boundaries. Agreement between the magnetic latitudes of the boundaries in both hemispheres is remarkable. Correlation coefficients between the latitudes of the boundaries are larger than 0.70. Temporal variation of the spectral width boundary follows the same equatorward trend in both hemispheres. This is consistent with the accumulation of open flux in the polar cap by dayside low-latitude magnetopause reconnection, expected when IMF Bz is negative. Boundaries in both hemispheres also exhibit short-lived poleward motions superposed on the general equator-ward trend, which follows the onset of substorm expansion phase and a temporary northward excursion of IMF Bz during substorm recovery phase. There is an interhemispheric difference in response time to the substorm occurrence between two hemispheres. The spectral width boundary in the Southern Hemisphere starts to move poleward 10 min earlier than that in the Northern Hemisphere. We discuss this difference in terms of interhemispheric asymmetry of the substorm breakup region in the longitudinal direction associated with the effect of IMF By.Key words. Ionosphere (ionosphere-magnetosphere interactions; plasma convection) – Magnetospheric physics (magnetopause, cusp, boundary layers)
An efficient algorithm for the large-scale smoothing of scattered data retrieved from remote sounding experiments
Authors: Fussen D.
Published: June 2010

Abstract. We present a new algorithm for smoothing/interpolation of two-dimensional fields applicable to noisy data observed at scattered sites. The technique is based on a special statistics allowing one to simultaneously minimize the fit residual and the correlation between residuals of adjacent points. The principle of the method is first explained in the 1-D case and then extended to the 2-D case by adjunction of a regularization operator. The method is compared with different algorithms (Loess-Renka, Biharmonic Spline and kriging) in three test cases related to remote sounding of the Earth’s atmosphere by space-borne experiments.Key words. Atmospheric composition and structure (evolution of the atmosphere; instruments and techniques; general or miscellaneous)
The penetration of ions into the magnetosphere through the magnetopause turbulent current sheet
Authors: Taktakishvili A. , Greco A. , Zimbardo G. , Veltri P. , Cimino G. , Zelenyi L. , Lopez R. E.
Published: June 2010

Abstract. This paper reports the results of numerical modeling of magnetosheath ion motion in the magnetopause current sheet (MCS) in the presence of magnetic fluctuations. Our model of magnetic field turbulence has a power law spectrum in the wave vector space, reaches maximum intensity in the center of MCS, and decreases towards the magnetosheath and magnetosphere boundaries. We calculated the density profile across the MCS. We also calculated the number of particles entering the magnetosphere, reflected from the magnetopause and escaping from the flanks, as a function of the fluctuation level of the turbulence and magnetic field shear parameter. All of these quantities appeared to be strongly dependent on the fluctuation level, but not on the magnetic field shear parameter. For the highest fluctuation levels the number of particles entering the magnetosphere does not exceed 15% of the total number of particles launched from the magnetosheath side of the MCS; the modeling also reproduced the effective reflection of the magnetosheath flow from very high levels of magnetic fluctuations.Key words. Magnetospheric physics (magnetosheath; magnetospheric configuration and dynamics; turbulence)
Space-borne clear air lidar measurements in the presence of broken cloud
Authors: Astin I. , Kiemle C.
Published: June 2010

Abstract. A number of proposed lidar systems, such as ESA’s AEOLUS (formerly ADM) and DIAL missions (e.g. WALES) are to make use of lidar returns in clear air. However, on average, two-thirds of the globe is covered in cloud. Hence, there is a strong likelihood that data from these instruments may be contaminated by cloud. Similarly, optically thick cloud may not be penetrated by a lidar pulse, resulting in unobservable regions that are overshadowed by the cloud. To address this, it is suggested, for example, in AEOLUS, that a number of consecutive short sections of lidar data (between 1 and 3.5 km in length) be tested for cloud contamination or for overshadowing and only those that are unaffected by cloud be used to derive atmospheric profiles. The prob-ability of obtaining profiles to near ground level using this technique is investigated both analytically and using UV air-borne lidar data recorded during the CLARE’98 campaign. These data were measured in the presence of broken cloud on a number of flights over southern England over a four-day period and were chosen because the lidar used has the same wavelength, footprint and could match the along-track spacing of the proposed AEOLUS lidar.Key words. Atmospheric composition and structure (aerosols and particles) Meteorology and atmospheric dynamics (instruments and techniques; general circulation)
Optical signatures of auroral arcs produced by field line resonances: comparison with satellite observations and modeling
Authors: Samson J. C. , Rankin R. , Tikhonchuk V. T.
Published: June 2010

Abstract. We show two examples from the CANOPUS array of the optical signatures of auroral arcs produced by field line resonances on the night of 31 January 1997. The first example occurs during local evening at about 18:00 MLT (Magnetic Local Time), where CANOPUS meridian scanning photometer data show all the classic features of field line resonances. There are two, near-monochromatic resonances (at approximately 2.0 and 2.5 mHz) and both show latitudinal peaks in amplitude with an approximately 180 degree latitudinal phase shift across the maximum. The second field line resonance event occurs closer to local midnight, between approximately 22:00 and 22:40 MLT. Magnetometer and optical data show that the field line resonance has a very low frequency, near 1.3 mHz. All-sky imager data from CANOPUS show that in this event the field line resonances produce auroral arcs with westward propagation, with arc widths of about 10 km. Electron energies are on the order of 1 keV. This event was also seen in data from the FAST satellite (Lotko et al., 1998), and we compare our observations with those of Lotko et al. (1998). A remarkable feature of this field line resonance is that the latitudinal phase shift was substantially greater than 180 degrees. In our discussion, we present a model of field line resonances which accounts for the dominant physical effects and which is in good agreement with the observations. We emphasize three points. First, the low frequency of the field line resonance in the second event is likely due to the stretched topology of the magnetotail field lines, with the field line resonance on field lines threading the earthward edge of the plasma sheet. Second, the latitudinal phase structure may indicate dispersive effects due to electron trapping or finite ion gyroradius. Third, we show that a nonlocal conductivity model can easily explain the parallel electric fields and the precipitating electron energies seen in the field line resonance.Key words. Magnetospheric physics (electric fields; energetic particles precipitating; current systems)
Interferometric radar observations of filamented structures due to plasma instabilities and their relation to dynamic auroral rays
Authors: Grydeland T. , Blixt E. M. , Løvhaug U. P. , Hagfors T. , La Hoz C. , Trondsen T. S.
Published: June 2010

Abstract. Several explanations have been proposed for Naturally Enhanced ion-acoustic Echoes observed at mid- and high-latitude Incoherent Scatter observatories. A decisive measure for distinguishing between these explanations is whether or not simultaneously observed up- and down-shifted enhancement occur simultaneously, or if they are the result of temporal and/or spatial averaging. The EISCAT Svalbard Radar has two antennas in the same radar system, which can be used as an interferometer when pointed parallel. In observations from 17 January 2002, between 06:46:10 and 06:46:30 UT, we used this possibility, in combination with direct sampling of the received signals, to yield measurements of "naturally enhanced ion-acoustic echoes" with sufficiently high resolution to resolve such averaging, if any. For the first time, radar interferometry has been employed to estimate the sizes of coherent structures. The observations were coordinated with an image intensified video camera with a narrow field of view. Together, this forms the initial study on the causal relationships between enhanced echoes and fine structure in the auroral activity on sub-kilometer, sub-second scales. The results confirm that the enhanced echoes originate from very localised regions (~300m perpendicular to the magnetic field at 500km altitude) with varying range distribution, and with high time variability (≈200ms). The corresponding increase in scattering cross section, up to 50dB above incoherent scattering, eliminates theoretical explanations based on marginal stability. The simultaneously observed up- and down-shifted enhanced shoulders, when caused by sufficiently narrow structures to be detected by the interferometer technique, originate predominantly from the same volume. These results have significant impact on theories attempting to explain the enhancements, in particular it is found that the ion-electron two-stream mechanism favoured by many authors is an unlikely candidate to explain the observations. The video data has helped establish a clear correlation between the enhanced echoes and auroral activity, on sub-second time scales, showing a threshold connection between the auroral intensity and the triggering of the radar enhancements. It appears that the up- and down-shifted enhanced echoes correlate with fine auroral structures in different ways. Key words. Ionosphere (auroral ionosphere; plasma waves and instabilities) – Radio science (interferometry)
Quantitative modelling of the closure of meso-scale parallel currents in the nightside ionosphere
Authors: Marchaudon A. , Cerisier J.-C. , Amm O. , Lester M. , Carlson C. W. , Parks G. K.
Published: June 2010

Abstract. On 12 January 2000, during a northward IMF period, two successive conjunctions occur between the CUTLASS SuperDARN radar pair and the two satellites Ørsted and FAST. This situation is used to describe and model the electrodynamic of a nightside meso-scale arc associated with a convection shear. Three field-aligned current sheets, one upward and two downward on both sides, are observed. Based on the measurements of the parallel currents and either the conductance or the electric field profile, a model of the ionospheric current closure is developed along each satellite orbit. This model is one-dimensional, in a first attempt and a two-dimensional model is tested for the Ørsted case. These models allow one to quantify the balance between electric field gradients and ionospheric conductance gradients in the closure of the field-aligned currents. These radar and satellite data are also combined with images from Polar-UVI, allowing for a description of the time evolution of the arc between the two satellite passes. The arc is very dynamic, in spite of quiet solar wind conditions. Periodic enhancements of the convection and of electron precipitation associated with the arc are observed, probably associated with quasi-periodic injections of particles due to reconnection in the magnetotail. Also, a northward shift and a reorganisation of the precipitation pattern are observed, together with a southward shift of the convection shear. Key words. Ionosphere (auroral ionosphere; electric fields and currents; particle precipitation) – Magnetospheric physics (magnetosphere-ionosphere interactions)
The impact of PMSE and NLC particles on VLF propagation
Authors: Nunn D. , Clilverd M. A. , Rodger C. J. , Thomson N. R.
Published: June 2010

Abstract. PMSE or Polar Mesosphere Summer Echoes are a well-known phenomenon in the summer northern polar regions, in which anomalous VHF/UHF radar echoes are returned from heights ~85km. Noctilucent clouds and electron density biteouts are two phenomena that sometimes occur together with PMSE. Electron density biteouts are electron density depletion layers of up to 90%, which may be several kms thick. Using the NOSC Modefndr code based on Wait's modal theory for subionospheric propagation, we calculate the shifts in received VLF amplitude and phase that occur as a result of electron density biteouts. The code assumes a homogeneous background ionosphere and a homogeneous biteout layer along the Great Circle Path (GCP) corridor, for transmitter receiver path lengths in the range of 500–6000km. For profiles during the 10h about midnight and under quiet geomagnetic conditions, where the electron density at 85km would normally be less than 500el/cc, it was found that received signal perturbations were significant, of the order of 1–4dB and 5–40° of phase. Perturbation amplitudes increase roughly as the square root of frequency. At short range perturbations are rather erratic, but more consistent at large ranges, readily interpretable in terms of the shifts in excitation factor, attenuation factor and v/c ratios for Wait's modes. Under these conditions such shifts should be detectable by a well constituted experiment involving multiple paths and multiple frequencies in the north polar region in summer. It is anticipated that VLF propagation could be a valuable diagnostic for biteout/PMSE when electron density at 85km is under 500el/cc, under which circumstances PMSE are not directly detectable by VHF/UHF radars. Key words. Electromagnetism (wave propagation) – Ionosphere (polar ionosphere) – Radioscience (ionospheric propagation)