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Author |
Legrand, M.; Preunkert, S.; Galy-Lacaux, C.; Liousse, C.; Wagenbach, D. |
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Title |
Atmospheric year-round records of dicarboxylic acids and sulfate at three French sites located between 630 and 4360 m elevation |
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Journal Article |
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Year |
2005 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
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110 |
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Keywords |
dicarboxylates; secondary production; high-elevated sites; 0365 Atmospheric Composition and Structure: Troposphere: composition and chemistry; 0368 Atmospheric Composition and Structure: Troposphere: constituent transport and chemistry; 0322 Atmospheric Composition and Structure: Constituent sources and sinks |
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An atmospheric year-round study of C2–C5 dicarboxylic acids (oxalic, malonic, succinic, malic, and glutaric) and sulfate was conducted in 2002 and 2003 at three remote western Europe continental sites located at different elevations (from 630 to 4360 m asl). Whatever the site and the season, oxalic acid is always the dominant diacid (average 64% of total dicarboxylic acids) followed by malonic acid (15% of total dicarboxylic acids). High correlation coefficients are observed between C3 (malonic), C4 (malic and succinic), and C5 (glutaric) acids and oxalic acid. These strong relationships between C2–C5 diacids support the hypothesis of a common production of these diacids through the aqueous phase chemistry of glutaric acid. Data gained at different elevations are here useful to compare the mass formation rates of sulfate and dicarboxylic acids. It is shown that in summer the decrease of the sum of dicarboxylic acids with height is far less pronounced than the decrease of sulfate (a factor of 2 instead of 6.8 from 630 to 4360 m asl). That demonstrates that the production of dicarboxylic acids occurs at up to 4300 m elevation while the production of sulfate from SO2 mainly takes place between the boundary layer and 3000 m elevation. With respect to summer 2002 the sum of dicarboxylic acids was enhanced in summer 2003 (from 136 to 331 ng m?3 STP at 2870 m asl, for instance) whereas a weaker increase is observed for sulfate (from 1700 to 2500 ng m?3 STP at 2870 m asl). These changes are attributed to the particular summer 2003 conditions which led to enhanced level of oxidants (strengthened secondary productions) and warmer temperatures (enhanced emissions of biogenic precursors of diacids). |
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414 |
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American Geophysical Union |
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0148-0227 |
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yes |
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IPEV @ Thierry.Lemaire @ |
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5575 |
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Pazmiño, A.F.; Godin-Beekmann, S.; Ginzburg, M.; Bekki, S.; Hauchecorne, A.; Piacentini, R.D.; Quel, E.J. |
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Title |
Impact of Antarctic polar vortex occurrences on total ozone and UVB radiation at southern Argentinean and Antarctic stations during 1997–2003 period |
Type |
Journal Article |
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Year |
2005 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
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Volume |
110 |
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Keywords |
polar ozone loss; UV radiation; polar vortex; 1610 Global Change: Atmosphere; 0341 Atmospheric Composition and Structure: Middle atmosphere: constituent transport and chemistry; 0340 Atmospheric Composition and Structure: Middle atmosphere: composition and chemistry |
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Abstract |
The evolution of total ozone and surface UV radiation over some stations in the southern region of South America and in Antarctica in relationship with polar vortex occurrences is analyzed using Total Ozone Mapping Spectrometer total ozone measurements and local surface UV data for the 1997–2003 period. The data are classified as a function of the position of the stations with respect to the polar vortex using equivalent latitude at 550 K isentropic level. The study of vortex occurrences showed that Ushuaia station (54.9°S) was located ?40% of the cases in the edge of the vortex and 5% inside the vortex core during the winter-spring period. Concerning the Marambio (62.2°S) and Dumont d'Urville (66.4°S) stations, located on the shore of the Antarctic continent, the analysis shows a zonal asymmetry with respect to the center of the vortex. Marambio is located around 60% of the time inside the vortex, while Dumont d'Urville is predominantly at the edge of or outside the vortex. The evolution of the equivalent latitude of the stations in the anomalous 2002 winter presents a different behavior with respect to other years in the 1997–2003 period. The persistence of the vortex core above the stations is in average 1.8 days over Ushuaia and 7.1 days over Marambio in October during the 1997–2003 period with corresponding mean total ozone columns of 208.2 and 181.4 Dobson units, respectively. When the stations are inside the vortex, the total ozone columns are generally larger at Ushuaia than at Marambio in October during the 1997–2003 period. Finally, the impact of ozone-depleted air mass occurrences on ultraviolet radiation is evaluated by relating total ozone and UV erythemal dose measured at the stations. Twofold or threefold UV dose increases were reached in the 55°–65° southern latitude region during vortex overpasses, reaching maximum UV dose around 5 kJ/m2. The average increase of UV dose could be computed at the stations considered in the study when the measurement sampling and the number of vortex occurrences was sufficient. An average increase of 67.6% of the erythemal UV dose was found in October at Ushuaia over the years 1997, 1998, and 2000. This value is strongly weighted by vortex occurrences over the station in 2000. At Marambio an average UV increase of 47.4% was found over the years 1999 and 2000. Midlatitude stations like Comodoro Rivadavia (45.8°S) are generally little affected by vortex intrusions. Nevertheless, the maximum UV dose can increase by more than 50% when the vortex passes over the station. |
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209 |
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American Geophysical Union |
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0148-0227 |
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yes |
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IPEV @ Thierry.Lemaire @ |
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5601 |
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Meijer, Y.J.; Swart, D.P.J.; Allaart, M.; Andersen, S.B.; Bodeker, G.; Boyd, I.; Braathen, G.; Calisesi, Y.; Claude, H.; Dorokhov, V.; von der Gathen, P.; Gil, M.; Godin-Beekmann, S.; Goutail, F.; Hansen, G.; Karpetchko, A.; Keckhut, P.; Kelder, H.M.; Koelemeijer, R.; Kois, B.; Koopman, R.M.; Kopp, G.; Lambert, J.-C.; Leblanc, T.; McDermid, I.S.; Pal, S.; Schets, H.; Stubi, R.; Suortti, T.; Visconti, G.; Yela, M. |
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Title |
Pole-to-pole validation of Envisat GOMOS ozone profiles using data from ground-based and balloon sonde measurements |
Type |
Journal Article |
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Year |
2004 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
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Volume |
109 |
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Keywords |
GOMOS; Envisat; ozone profile; validation; stratosphere; remote sensing; 0365 Atmospheric Composition and Structure: Troposphere—composition and chemistry; 0394 Atmospheric Composition and Structure: Instruments and techniques; 3360 Meteorology and Atmospheric Dynamics: Remote sensing; 3394 Meteorology and Atmospheric Dynamics: Instruments and techniques |
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Abstract |
In March 2002 the European Space Agency (ESA) launched the polar-orbiting environmental satellite Envisat. One of its nine instruments is the Global Ozone Monitoring by Occultation of Stars (GOMOS) instrument, which is a medium-resolution stellar occultation spectrometer measuring vertical profiles of ozone. In the first year after launch a large group of scientists performed additional measurements and validation activities to assess the quality of Envisat observations. In this paper, we present validation results of GOMOS ozone profiles from comparisons to microwave radiometer, balloon ozonesonde, and lidar measurements worldwide. Thirty-one instruments/launch sites at twenty-five stations ranging from the Arctic to the Antarctic joined in this activity. We identified 6747 collocated observations that were performed within an 800-km radius and a maximum 20-hour time difference of a satellite observation, for the period between 1 July 2002 and 1 April 2003. The GOMOS data analyzed here have been generated with a prototype processor that corresponds to version 4.02 of the operational GOMOS processor. The GOMOS data initially contained many obviously unrealistic values, most of which were successfully removed by imposing data quality criteria. Analyzing the effect of these criteria indicated, among other things, that for some specific stars, only less than 10% of their occultations yield an acceptable profile. The total number of useful collocated observations was reduced to 2502 because of GOMOS data unavailability, the imposed data quality criteria, and lack of altitude overlap. These collocated profiles were compared, and the results were analyzed for possible dependencies on several geophysical (e.g., latitude) and GOMOS observational (e.g., star characteristics) parameters. We find that GOMOS data quality is strongly dependent on the illumination of the limb through which the star is observed. Data measured under bright limb conditions, and to a certain extent also in twilight limb, should be used with caution, as their usability is doubtful. In dark limb the GOMOS data agree very well with the correlative data, and between 14- and 64-km altitude their differences only show a small (2.5–7.5%) insignificant negative bias with a standard deviation of 11–16% (19–63 km). This conclusion was demonstrated to be independent of the star temperature and magnitude and the latitudinal region of the GOMOS observation, with the exception of a slightly larger bias in the polar regions at altitudes between 35 and 45 km. |
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209 |
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American Geophysical Union |
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0148-0227 |
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yes |
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IPEV @ Thierry.Lemaire @ |
Serial |
5620 |
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Author |
Parrenin, F.; Rémy, F.; Ritz, C.; Siegert, M.J.; Jouzel, J. |
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Title |
New modeling of the Vostok ice flow line and implication for the glaciological chronology of the Vostok ice core |
Type |
Journal Article |
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Year |
2004 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
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109 |
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Keywords |
glaciology; paleoclimatology; Antarctica; inverse theory; 1827 Hydrology: Glaciology; 3344 Meteorology and Atmospheric Dynamics: Paleoclimatology; 3260 Mathematical Geophysics: Inverse theory; 9310 Information Related to Geographic Region: Antarctica |
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Abstract |
We have used new spaceborne (elevation) and airborne (ice thickness) data to constrain a 2D1/2 model of snow accumulation and ice flow along the Ridge B-Vostok station ice flow line (East Antarctica). We show that new evaluations of the ice flow line geometry (from the surface elevation), ice thickness (from low-frequency radar data), and basal melting and sliding change significantly the chronology of the Vostok ice core. This new Vostok dating model reconciles orbital and glaciological timescales and is in good agreement with the Dome Fuji glaciological timescale. At the same time, the new model shows significantly older ages than the previous GT4 timescale for the last glacial part, being thus in better agreement with the GRIP and GISP2 chronologies. |
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355 |
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American Geophysical Union |
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0148-0227 |
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yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5618 |
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Author |
Bouruet-Aubertot, P.; Mercier, H.; Gaillard, F.; Lherminier, P. |
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Title |
Evidence of strong inertia-gravity wave activity during the POMME experiment |
Type |
Journal Article |
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Year |
2005 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
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Volume |
110 |
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Keywords |
inertia-gravity waves, turbulent mixing; 4544 Oceanography: Physical: Internal and inertial waves; 4568 Oceanography: Physical: Turbulence, diffusion, and mixing processes; 4572 Oceanography: Physical: Upper ocean and mixed layer processes |
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Abstract |
The purpose of this paper is to characterize inertia-gravity waves (IGW) activity and to investigate the variability of these waves in relationship to atmospheric forcing and larger-scale motions. To this aim, we analyzed Eulerian measurements of horizontal currents and temperature collected over 1 year during the Programme Océan Multidisciplinaire Méso Echelle (POMME). We focused on the main frequency components of the IGW spectrum, namely the inertial frequency f and the semidiurnal frequency M2. Time evolution of the relative energy of these two components gave evidence of isolated events of high intensity. We performed a detailed analysis of these events and identified mechanisms of generation of these waves. Localized spots of intense, near-inertial IGW were observed in winter. During the mixed layer deepening, one event was correlated with plume-like structures resulting from peaks of intense surface cooling. This suggests a local generation process driven by strong downward vertical motions. Instead, other events of strong IGW could be related to submesoscale features, characteristic of a frontal region, in particular, wave trapping within anticyclonic eddies. In contrast, a downward energy propagation down to about 500 m below the mixed layer was isolated after a stormy period. Eventually, internal tidal beams, possibly generated at a nearby seamount, intermittently crossed the mooring, though less energetically than the previous events. Last, we estimated the eddy diffusivity from the velocity vertical shear. Large variations were obtained, from 10?6 m2/s up to 10?3 m2/s, consistent with the intense events previously isolated. |
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417 |
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American Geophysical Union |
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0148-0227 |
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yes |
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IPEV @ Thierry.Lemaire @ |
Serial |
5590 |
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Thuillier, G.; Perrin, J.-M.; Lathuillère, C.; Hersé, M.; Fuller-Rowell, T.; Codrescu, M.; Huppert, F.; Fehrenbach, M. |
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Title |
Dynamics in the polar thermosphere after the coronal mass ejection of 28 October 2003 observed with the EPIS interferometer at Svalbard |
Type |
Journal Article |
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Year |
2005 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
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Volume |
110 |
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Keywords |
thermosphere; CME; neutral winds; EPIS; ESR; 0310 Atmospheric Composition and Structure: Airglow and aurora; 0358 Atmospheric Composition and Structure: Thermosphere: energy deposition; 7513 Solar Physics, Astrophysics, and Astronomy: Coronal mass ejections |
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The upper atmosphere dynamics in the polar cap is mainly driven by ion-drag momentum sources imposed by the mapping of magnetosphere convection into the thermosphere/ionosphere and by Joule and auroral particle heating. Auroral particles also enhance conductivity particularly in the middle and lower ionosphere. Changes in the magnetospheric energy and momentum sources can significantly modify the wind circulation during geomagnetic storms. To observe these effects, a Michelson interferometer has been installed in Svalbard to measure winds in the thermosphere. Prior to 30 October 2003, cloud cover over Svalbard rendered the conditions unfavorable for optical observation. However, meteorological conditions improved after this date to enable the thermospheric response to the 28 October coronal mass ejection to be made. During quiet geomagnetic conditions measured wind velocities were in good agreement with those predicted by the Horizontal Wind Model (HWM). During disturbed geomagnetic conditions, HWM tended to underestimate the observed velocities. Comparison of the wind observations with a physical model tended to show reasonable agreement during both the strongly driven and recovery phase of the storm. Although the physical model did not always capture the timing of the rapid changes in the wind response in the early phase of the storm, the amplitudes of the fluctuations were in good agreement. After the initial phase the physical model agreed well with both the timing and amplitude of the meridional and zonal wind fluctuations. The meridional wind component was also derived from the EISCAT Svalbard Radar ion velocity and was found to be in close agreement with the optical winds observations. |
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384 |
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American Geophysical Union |
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0148-0227 |
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yes |
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IPEV @ Thierry.Lemaire @ |
Serial |
5585 |
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Cerisier, J.-C.; Marchaudon, A.; Bosqued, J.-M.; McWilliams, K.; Frey, H.U.; Bouhram, M.; Laakso, H.; Dunlop, M.; Förster, M.; Fazakerley, A. |
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Title |
Ionospheric signatures of plasma injections in the cusp triggered by solar wind pressure pulses |
Type |
Journal Article |
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Year |
2005 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
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Volume |
110 |
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Keywords |
flux transfer events; cusp; reconnection; flow bursts; solar wind pressure; 2463 Ionosphere: Plasma convection; 2712 Magnetospheric Physics: Electric fields; 2716 Magnetospheric Physics: Energetic particles: precipitating; 2736 Magnetospheric Physics: Magnetosphere/ionosphere interactions; 2784 Magnetospheric Physics: Solar wind/magnetosphere interactions |
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Abstract |
We describe coordinated observations made on 14 July 2001 simultaneously in the midaltitude cusp by Cluster and at the cusp's ionospheric magnetic footprint by Super Dual Auroral Radar Network (SuperDARN) and Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) during a period of three successive solar wind dynamic pressure pulses. In association with each of these pulses, Cluster observes plasma injections while auroral images from the IMAGE spacecraft show enhanced precipitation in the cusp. Following these plasma injections, channels of fast convection flows are observed in the ionosphere by the SuperDARN radars. On the basis of the spatial and temporal relationships between these various signatures, we analyze the response of the dayside magnetosphere and ionosphere to the pressure pulses as follows: (1) the solar wind dynamic pressure pulses are the drivers of plasma injections from the magnetosheath into the cusp; (2) the ionospheric convection bursts start shortly after the auroral intensifications and their duration is much longer (10 min versus 4–6 min for the auroral intensifications); (3) the convection bursts occur on the poleward side of the cusp precipitation; and (4) the Alfvén waves that are responsible of the transmission of the magnetic stress from the reconnection site to the ionosphere are strongly reflected in the upper ionosphere. This, in addition to possible parallel potential drops, may explain the imperfect mapping of the magnetospheric electric field into the ionosphere during the injections. These observations demonstrate that the convection bursts are “fossil” signatures of the compression–injection process, which is also a signature of reconnection at the dayside magnetopause driven by the interplanetary magnetic field alone. |
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312;911 |
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American Geophysical Union |
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0148-0227 |
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yes |
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IPEV @ Thierry.Lemaire @ |
Serial |
5608 |
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Miroshnichenko, L.I.; Klein, K.-L.; Trottet, G.; Lantos, P.; Vashenyuk, E.V.; Balabin, Y.V.; Gvozdevsky, B.B. |
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Title |
Relativistic nucleon and electron production in the 2003 October 28 solar event |
Type |
Journal Article |
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Year |
2005 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
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Volume |
110 |
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Keywords |
relativistic solar cosmic rays; GLE modeling; interplanetary propagation; solar radioemissions; flare ejecta; IMF loop structures; 2104 Interplanetary Physics: Cosmic rays; 2111 Interplanetary Physics: Ejecta, driver gases, and magnetic clouds; 2114 Interplanetary Physics: Energetic particles; 7534 Solar Physics, Astrophysics, and Astronomy: Radio emissions; 7519 Solar Physics, Astrophysics, and Astronomy: Flares |
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Abstract |
A flare on 2003 October 28 produced a relativistic particle event at Earth, although the active region AR 10486 was located to the east of the central meridian of the Sun. The paper considers features related to the acceleration at the Sun and the propagation to the Earth of energetic particles in this event, which occurred on a disturbed interplanetary background caused by preceding activity on the Sun and a corotating high-speed solar wind stream. From a study of the onset times of the event at different neutron monitors, we conclude that the earliest arriving solar particles were neutrons. The first relativistic protons arrived a few minutes later. Among relativistic solar protons (RSP), two populations could clearly be distinguished: prompt and delayed ones. The prompt solar protons caused an impulse-like increase at a few neutron monitor stations. The delayed solar protons arrived at Earth 0.5 hours later. Both prompt and delayed relativistic protons arrived at Earth from the antisunward direction. On the other hand, subrelativistic electrons that were traced by their radio emission from meter waves (Nançay Radioheliograph and Decametric Array) to kilometer waves (Wind/WAVES) are accompanied by metric radio emission in the western solar hemisphere, far from the flaring active region. We propose a scenario that reconciles the unusual features of energetic particles at the Earth with the observed structure of the interplanetary magnetic field, which suggests the Earth is at the interface between an interplanetary coronal mass ejection (ICME) and a corotating stream during the event. In this scenario the high-energy protons and electrons are accelerated in the flaring active region, injected into the eastern leg of an ICME loop rooted in the active region, and reach the Earth from the antisunward direction after passing through the summit of the loop. We attribute the promptly escaping subrelativistic electrons to acceleration in the western solar hemisphere and propagation along the nominal Parker spiral. |
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227 |
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American Geophysical Union |
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0148-0227 |
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yes |
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IPEV @ Thierry.Lemaire @ |
Serial |
5625 |
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Author |
Francia, P.; Lanzerotti, L.J.; Villante, U.; Lepidi, S.; Di Memmo, D. |
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Title |
A statistical analysis of low-frequency magnetic pulsations at cusp and cap latitudes in Antarctica |
Type |
Journal Article |
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Year |
2005 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
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Volume |
110 |
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Pages |
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Keywords |
polar cap and cusp pulsations; magnetospheric wave guide modes; field line resonances; open/closed field line boundary; 2784 Magnetospheric Physics: Solar wind/magnetosphere interactions; 2740 Magnetospheric Physics: Magnetospheric configuration and dynamics; 2776 Magnetospheric Physics: Polar cap phenomena; 2706 Magnetospheric Physics: Cusp; 2752 Magnetospheric Physics: MHD waves and instabilities |
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Abstract |
We report a statistical analysis of low-frequency magnetic variations (magnetic pulsations, 0.8–7 mHz) at South Pole (74°S corrected geomagnetic latitude) and Terra Nova Bay (80°S) during 1996. The results show that at South Pole (at cusp latitudes) the pulsation power exhibits two maxima during the day, one in the local premidnight and the other in the morning. The first maximum disappears when the analysis is restricted to northward interplanetary magnetic field conditions (B z > 1 nT), suggesting that it might be associated to substorm phenomena. During closed magnetospheric conditions, when the cusp is expected to be located poleward with respect to the station, the spectral and polarization characteristics of pulsations between 1 and 3 mHz suggest that resonant oscillations of the outermost closed field lines commonly occur at South Pole in the local morning. At Terra Nova Bay, in the polar cap, the pulsation power is much lower and its diurnal variation is characterized by a single maximum, which occurs around local noon, when the station approaches the cusp. The corresponding polarization pattern indicates that Terra Nova Bay is always located poleward with respect to resonant field lines. |
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1130 |
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American Geophysical Union |
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ISSN |
0148-0227 |
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Approved |
yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5495 |
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Author |
Chulliat, A.; Blanter, E.; Le Mouël, J.-L.; Shnirman, M. |
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Title |
On the seasonal asymmetry of the diurnal and semidiurnal geomagnetic variations |
Type |
Journal Article |
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Year |
2005 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
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Volume |
110 |
Issue |
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Pages |
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Keywords |
daily variation; lower thermospheric winds; ionospheric dynamo; current system; geomagnetic activity; equinoxes; 1555 Geomagnetism and Paleomagnetism: Time variations: diurnal to decadal; 2437 Ionosphere: Ionospheric dynamics; 3369 Atmospheric Processes: Thermospheric dynamics; 3389 Atmospheric Processes: Tides and planetary waves |
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Abstract |
The diurnal and semidiurnal variations of the geomagnetic field are investigated at 18 observatories using long series of hourly values (up to 97 years at Sitka). The seasonal variations of amplitude of the 12-hour and 24-hour lines are obtained for the H and Z components using a 28-day sliding window. The Fourier analysis is performed using either all days within the window or only the five quietest days. At midlatitudes a strong lack of symmetry about the summer solstice is observed for both lines and both components. This effect is enhanced when selecting quiet days. When averaged over the entire series, the sign of this seasonal asymmetry is the same at 9 out of 10 midlatitude observatories for both lines and for a given component; it is opposite for the H and Z components. Such a coherent seasonal asymmetry is not found at low and high latitudes. At high latitudes a strong annual variation is found inside the polar caps, while a strong semiannual variation is found in the auroral zones. When selecting quiet days, these two effects are weaker, and the seasonal asymmetry becomes comparable to that at midlatitudes. At all latitudes the year-to-year variations of the seasonal asymmetry are uncorrelated with solar activity. It is suggested that lower thermospheric winds may have a similar seasonal asymmetry between spring and autumn equinoxes. Such an asymmetry is present in the published literature but has been overlooked. Possible causes for this wind asymmetry are reviewed. |
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Programme |
139 |
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Publisher |
American Geophysical Union |
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Abbreviated Series Title |
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ISSN |
0148-0227 |
ISBN |
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Conference |
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Notes |
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Approved |
yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5485 |
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| Permanent link to this record |
