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  • 1.
    Arvelius, Johan
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Rymdvetenskap.
    Calibration and quality assessment of DESCARTES: grabsampler for stratospheric tracers2005Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    DESCARTES is a light-weight, balloon-borne grab sampler for stratospheric long-lived tracers developed at the University of Cambridge. 33 flights have been performed with two versions of the instrument at northern latitudes by the DESCARTES team at the Swedish Institute of Space Physics (IRF) in Kiruna during the years 1997-2000.

    The general interest in long-lived stratospheric tracers is to study the general global circulation of air in the stratosphere and the exchange between the stratosphere and troposphere. In the study of chemical ozone depletion in the stratosphere, long-lived tracers serve as an important reference to distinguish between the variations in ozone of dynamical and chemical origin.

    This thesis focuses on calibrations and quality assessment of the measurements made with the third version of the DESCARTES instrument based at IRF. Two different general approaches to make calibrations are discussed. Uncertainty estimations for both of these methods are made and the results are tested by laboratory methods and by comparisons to other instruments, including comparisons between two versions of DESCARTES. Analyzed and calibrated flight data for all successful flights are presented.

    The basic principle of the instrument is to chemically adsorb a number of tracers (in practice only CFC-11 is measured) in an adsorption bed of Carboxen in a micro trap through which the sampled air is driven by a pump. After recovery the adsorbed species in the trap is desorbed by electrical heating of the trap and analysed by gas chromatography.

    The resulting estimated mixing ratios from the instrument are directly dependent on the adsorption of the sampled species being quantitative in the traps. Laboratory experiments are described using two traps in series, where the performance of the first is tested by sampling the breakthrough by the second. A model is developed to recreate these tests in order to be able to compensate for breakthrough during flights. The model showed that the adsorption in the traps is not explained by simple chromatographic theory and the results allow us only to give an estimation of the uncertainty due to breakthrough.

  • 2.
    Arvelius, S.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Rymdvetenskap.
    Yamauchi, M.
    Nilsson, H.
    Lundin, R.
    Hobara, Y.
    Rème, H.
    Bavassano- Cattaneo, M. B.
    Paschmann, G.
    Korth, A.
    Kistler, L. M.
    Parks, G. K.
    Statistical study of relationships between dayside high-altitude and high-latitude O+ ion outflows, solar winds, and geomagnetic activity2005Inngår i: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 23, 1909-1916 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The persistent outflows of O+ ions observed by the Cluster CIS/CODIF instrument were studied statistically in the high-altitude (from 3 up to 11 RE) and high-latitude (from 70 to ~90 deg invariant latitude, ILAT) polar region. The principal results are: (1) Outflowing O+ ions with more than 1keV are observed above 10 RE geocentric distance and above 85deg ILAT location; (2) at 6-8 RE geocentric distance, the latitudinal distribution of O+ ion outflow is consistent with velocity filter dispersion from a source equatorward and below the spacecraft (e.g. the cusp/cleft); (3) however, at 8-12 RE geocentric distance the distribution of O+ outflows cannot be explained by velocity filter only. The results suggest that additional energization or acceleration processes for outflowing O+ ions occur at high altitudes and high latitudes in the dayside polar region.

  • 3.
    Arvelius, S.
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Rymdvetenskap.
    Yamauchi, M.
    Nilsson, H.
    Lundin, R.
    Y., Hobara
    Rème, H.
    Bavassano- Cattaneo, M. B.
    Paschmann, G.
    Korth, A.
    Kistler, L. M.
    Parks, G. K.
    Statistics of high-altitude and high-latitude O+ ion outflows observed by Cluster/ CIS2005Inngår i: Annales Geophysicae, Vol. 23, 1909–1916- s.Artikkel i tidsskrift (Fagfellevurdert)
  • 4.
    Arvelius, Sachiko
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Rymdvetenskap.
    Energization and Acceleration of Dayside Polar Outflowing Oxygen2005Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis deals with energetic oxygen ions (i.e. single-charged atomic oxygen ions, O+) at altitudes higher than 5 Earth radii (RE) and at latitudes above 75 (toward 90) degrees invariant latitude (deg ILAT) in the dayside polar magnetosphere observed by Cluster. The instrument used in this study is CIS (Cluster Ion Spectrometry experiment) / CODIF (a time-of-flight ion COmposition and DIstribution Function analyser), which covers an energy range from »10 eV up to 38 keV. Cluster detected O+ with energies more than 1 keV (hereafter termed “keV O+”), indicating that energization and/or acceleration process(es) take place in the dayside high-altitude (inside magnetopause) and high-latitude region. These O+ are outflowing (precisely, upward-going along the geomagnetic field lines), and these outflowing keV O+ show a heated (or energized) signature in the velocity distribution as well.

    First, outflowing O+ are observed at the poleward cusp and/or the mantle formed a partial shell-like configuration seen in the velocity distribution. Second, the latitudinal distribution of outflowing O+ (most of them have energies less than 1 keV statistically) observed below 7 RE is consistent with velocity filter effect by the polar convection, while the latitudinal distribution of outflowing keV O+ observed above 7 RE cannot be explained by velocity filter effect only, i.e. this indicates that additional energization and/or acceleration takes place at higher altitudes in the dayside polar region. Thirdly, a tendency to observe outflowing keV O+ for during different geomagnetic conditions is studied. The keV O+ above 9 RE is more often for K p¸5 rather than for K p•3. However the energy of O+ is not dependent on ASY /SYM indices.

    Finally, the dependence on the solar wind conditions is also studied. The energization and/or acceleration of outflowing O+ is controlled by both solar wind moments (except solar wind electric field) and strong southward interplanetary magnetic field (IMF) at the time scale of tens of minutes at only higher altitudes. Further examination shows that solar wind dependence is different at three regions: one is the poleward cusp, another is the low-altitude polar cap, and finally the high-altitude polar cap, combining all the results. There is (a) new energization and/or acceleration process(es) at the high-altitude polar cap. On the other hand, flux enhancement of O+ observed above 5 RE is also controlled by solar wind moments (e.g. solar wind electric field) and strong southward IMF, however the ionospheric changes play a more important role on the flux enhancement of O+.

  • 5.
    Brinkfeldt, Klas
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Rymdvetenskap.
    Instrumentation for energetic Neutral atom measurements at Mars, Venus and The Earth2005Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    This thesis deals with the development and calibrations of sensors to measure energetic neutral atoms (ENAs) at Mars, Venus, and the Earth. ENAs are formed in charge exchange processes between energetic, singly--charged ions and a cold neutral gas. Since ENAs can travel in long straight trajectories, unaffected by electric or magnetic fields, they can be used to remotely image plasma interactions with neutral atmospheres. ENA instrument techniques have matured over the last decade and ENA images of the Earth's ring current for example, have successfully been analyzed to extract ion distributions and characterize plasma flows and currents in the inner magnetosphere.

    Three different ENA sensors have been developed to image ENAs at Mars, Venus, and the Earth. Two of them, the nearly identical Neutral Particle imagers (NPIs) are on-board the Mars Express and Venus Express spacecraft as a part of the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3 and 4) instruments. The third is the Neutral Atom Detector Unit, NUADU, aboard the TC-2 spacecraft of the Double Star mission. The NPI design is based on a surface reflection technique to measure low energy (~0.3-60 keV) ENAs, while the NUADU instrument is based on a simple design with large geometrical factor and solid state detectors to measure high energy ENAs (~20-300 keV).

    The calibration approach of both NPI sensors were to define the detailed response, including properties such as the angular response function and efficiency of one reference sensor direction then find the relative response of the other sensor directions. Because of the simple geometry of the NUADU instrument, the calibration strategy involved simulations to find the cutoff energy, geometrical factor and angular response. The NUADU sensor head was then calibrated to find the response to particles of different mass and energy. The NPI sensor for the Mars Express mission revealed a so-called priority effect in the sensor that lowers the angular resolution at high detector bias. During the calibration of the Venus Express NPI sensor tests were made which showed that the priority effect is a result of low amplitude (noise) pulses generated in the detector system. The conclusion is that the effect is caused by capacitive couplings between different anode sectors of the sensor. The thresholds on the preamplifiers were set higher on the Venus Express NPI, which removed the priority effect.

    Two of the three ENA experiments, the Double Star NUADU instrument and the Mars Express NPI sensor, have successfully measured ENAs that are briefly described in the thesis. The first ENA measurements at Mars were performed with Mars Express. Initial results from the NPI include measurements of ENAs formed in the Martian magnetosheath and solar wind ENAs penetrating to the nightside of Mars. The first results from NUADU in Earth orbit show the expected ENA emissions from a storm time ring current. Also, together with the HENA instrument on the IMAGE spacecraft, NUADU have produced the first multi-point ENA image of the ring current.

  • 6.
    Brändström, Urban
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Rymdvetenskap.
    The Auroral Large Imaging System: design, operation and scientific results2003Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    The Auroral Large Imaging System (ALIS) was proposed in 1989 by Åke Steen as a joint Scandinavian ground-based nework of automated auroral imaging stations. The primary scientic objective was in the field of auroral physics, but it was soon realised that ALIS could be used in other fields, for example, studies of Polar Stratospheric Clouds (PSC), meteors, as well as other atmospheric phenomena.

    This report describes the design, operation and scientic results from a Swedish prototype of ALIS consisting of six unmanned remote-controlled stations located in a grid of about 50 km in northern Sweden. Each station is equipped with a sensitive high-resolution (1024 x 1024 pixels) unintensified monochromatic CCDimager. A six-position filter-wheel for narrow-band interference filters facilitates absolute spectroscopic measurements of, for example, auroral and airglow emissions. Overlapping fields-of-view resulting from the station baseline of about 50 km combined with the station field-of-view of 50° to 60°, enable triangulation as well as tomographic methods to be employed for obtaining altitude information of the observed phenomena.

    ALIS was probably one of the first instruments to take advantage of unintensi- fied (i.e. no image-intensifier) scientific-grade CCDs as detectors for spectroscopic imaging studies with multiple stations of faint phenomena such as aurora, airglow, etc. This makes absolute calibration a task that is as important as it is dificult.

    Although ALIS was primarily designed for auroral studies, the majority of the scientific results so far have, quite unexpectedly, been obtained from observations of HF pump-enhanced airglow (recently renamed Radio-Induced Aurora). ALIS made the first unambiguous observation of this phenomena at high-latitudes and the first tomography-like inversion of height profiles of the airglow regions. The scientific results so far include tomographic estimates of the auroral electron spectra, coordinated observations with satellite and radar, as well as studies of polar stratospheric clouds. An ALIS imager also participated in a joint project that produced the first ground-based daytime auroral images. Recently ALIS made spectroscopic observations of a Leonid meteor-trail and preliminary analysis indicates the possible detection of water in the Leonid.

  • 7.
    Grigoriev, Alexander
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Rymdvetenskap.
    The Neutral Particle Detector on the Mars and Venus Express missions2007Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    The Neutral Particle Detector (NPD) is a new type of instrumentation for energetic neutral atom (ENA) diagnostics. This thesis deals with development of the NPD sensor designed as a part of the plasma and neutral particle packages ASPERA-3 and ASPERA-4 on board Mars Express and Venus Express, the European Space Agency (ESA) satellites to Mars and Venus, respectively. It describes how the NPD sensors were designed, developed, tested and calibrated.

    It also presents the first scientific results obtained with NPD during its operation at Mars.

    The NPD package consists of two identical detectors, NPD1 and NPD2. Each detector has a 9o x 90o intrinsic field-of-view divided into three sectors. The ENA detection principle is based on the surface interaction technique. NPD detects ENA differential fluxes within the energy range of 100 eV to 10 keV and is capable of resolving hydrogen and oxygen atoms by time-of-flight (TOF) measurements or pulse height analysis.

    During the calibration process the detailed response of the sensor was defined, including properties such as an angular response function and energy dependent efficiency of each of the sensor sectors for different ENA species.

    Based on the NPD measurements at Mars the main scientific results reported so far are:

    - observation of the Martian H-ENA jet / cone and its dynamics,

    - observations of ENA emissions from the Martian upper atmosphere,

    - measurements of the hydrogen exosphere density profile at Mars,

    - observations of the response of the Martian plasma environment to an interplanetary shock,

    - observations of the H-ENA fluxes in the interplanetary medium.

  • 8.
    Inga, Mikael
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Rymdvetenskap.
    REXUS II: rocket borne experiments for university students2005Inngår i: 17th ESA symposium on European rocket and balloon programmes and related research, Paris: European Space Agency, 2005, Vol. 590, 81-85 s.Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    This paper is about the student part of REXUS II. Students at the Department of Space Science were invited to join a EUROLAUNCH rocket campaign. This was done with a short time of notice but we accepted the offer and have tried to do our best despite the lack of time. The attendees are spread over several programs at the Umea University, Lulea University of Technology and Upper Secondary Space School, Kiruna which has lead to some interesting and challenging problems for the project managers. The launch of the rocket, an improved Orion rocket, was a success. It was launched from SSC, Esrange at 21:53 local time the 28(th) of October 2004. All of the experiments didn't deliver the expected data or didn't even work but still the members of the experiment teams did learn a lot. So, despite the faults it was still a success if the participators someday use the gained knowledge and experience.

  • 9. Karpetchko, Alexei
    et al.
    Nikulin, Grigory
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Rymdvetenskap.
    Influence of early winter upward wave activity flux on midwinter circulation in the stratosphere and troposphere2004Inngår i: Journal of Climate, ISSN 1520-0442, Vol. 17, nr 22, 4443-4452 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 10.
    Nikulin, Grigory
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Rymdvetenskap.
    Impact of Rossby waves on ozone distribution and dynamics of the stratosphere and troposphere2005Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Several physical mechanisms concerning the impact of Rossby waves on ozone distribution and circulation in the stratosphere and troposphere are studied in the thesis.

    Summertime total ozone variability over Middle Asia and Northern Scandinavia shows similar wave-like behaviour with typical periods of 10-20 days and amplitudes of 20-50 Dobson units. These variations are caused by eastward travelling Rossby waves in the lower stratosphere. The same mechanism plays the primary role in the formation of an intense low ozone episode over Scandinavia in August 2003. A strong anticyclone was formed in the troposphere over Europe as a part of a Rossby wave train. The anticyclone coincides with a displaced Artic pool of low-ozone air in the stratosphere aloft of the anticyclone. A combination of the two above-mentioned processes results in the total ozone minimum over Northern Europe for summer 2003.

    Interannual variability of the atmospheric circulation and total ozone during winter is strongly controlled by the diabatic (Brewer-Dobson) circulation which is driven by upward propagating waves from the troposphere. In the Northern Hemisphere midlatitudes, wintertime total ozone shows antiphase behaviour with the Arctic Oscillation (AO) index on interannual and decadal time-scales. Weaker (stronger) wave activity leads to less (more) northward ozone transport and to a stronger (weaker) AO.

    Rossby wave activity occurs as episodic wave events and this wave forcing is not uniform during winter. The November-December stratospheric eddy heat flux is strongly anticorrelated with the January-February eddy heat flux in the midlatitude stratosphere and troposphere. Weaker upward wave fluxes in early winter lead to stronger upward wave fluxes from the troposphere as well as to a stronger polar night jet during midwinter and vice versa. Hence upward wave activity fluxes in early winter define, to a considerable extent, the subsequent evolution of the midwinter circulation in the stratosphere and troposphere.

  • 11.
    Nikulin, Grigory
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Rymdvetenskap.
    Karpechko, Alexei
    The mean meridional circulation and midlatitude ozone buildup2005Inngår i: Atmospheric Chemistry and Physics Discussions, ISSN 1680-7367, E-ISSN 1680-7375, Vol. 5, 3159-3172 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The wintertime ozone buildup over the Northern Hemisphere (NH) midlatitudes and its connection with the mean meridional circulation in the stratosphere are examined statistically on a monthly basis from October to March ( 1980 - 2002). The ozone buildup begins locally in October with positive total ozone tendencies over the North Pacific, which spread eastward and westward in November and finally cover all midlatitudes in December. The local onset of the buildup in October is not evident in zonal mean ozone tendency, which is close to zero. From November to March, zonal mean total ozone tendency (50 degrees - 60 degrees N) shows a strong correlation (|r|= 0.7) with several zonal mean parameters associated to the mean meridional circulation, namely: eddy heat flux, temperature tendency, the vertical residual velocity and the residual streamfunction. At the same time, on the latitude-altitude cross section, correlation patterns between ozone tendency and widely used eddy heat flux are not uniform during winter. The strongest correlations are located equatorward ( almost throughout the stratosphere) or poleward ( only in the lower stratosphere) of the edge of the polar vortex. Such distribution may depend on the existence of the midlatitude and polar waveguides which defined refraction of upward propagating waves from the troposphere either to the midlatitude stratosphere or to the polar stratosphere. As a consequence of the nonuniform correlation patterns, heat flux averaged over the common region 45 degrees - 75 degrees N, 100 hPa is not always an optimum proxy for statistical models describing total ozone variability in midlatitudes. Other parameters approximating the strength of the mean meridional circulation have more uniform and stable correlation patterns with ozone tendency during winter. We show that the NH midlatitude ozone buildup has a stable statistical relationship with the mean meridional circulation in all months from October to March and half of the interannual variability in monthly ozone tendencies can be explained by applying different proxies of the mean meridional circulation.

  • 12.
    Nikulin, Grigory
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Rymdvetenskap.
    Repinskya, Raisa P.
    Modulation of total ozone anomalies in the midlatitude Northern Hemesphere by the Arctic oscillation2001Inngår i: Izvestia - Atmospheric and Oceanic Physics, ISSN 0001-4338, Vol. 37, nr 5, 633-643 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 13.
    Norberg, Carol
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Rymdvetenskap.
    Recent developments in space education in Kiruna, Sweden2005Inngår i: 17th ESA Symposium on European Rocket and Balloon Programmes and Related Research, Paris: European Space Agency, 2005, 61-62 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The two most northern universities in Sweden, Lulea University of Technology and Umea University have formed a joint Department of Space Science located in Kiruna. The department is responsible for programmes covering a wide spectrum, practically oriented and more theoretical, leading to Bachelor's and Master's degrees in space engineering. In addition the universities have graduate education in space and atmospheric physics and space technology. Recent developments include the award by the European Commission of funding for an Erasmus Mundus Space Master Course, which is a cooperative project with five other European universities and an expansion of the department's summer programme to include a course in manned space flight.

  • 14. Orsolin, Yvan J.
    et al.
    Nikulin, Grigory
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Rymdvetenskap.
    A low-ozone episode during the European heat wave of August 20032006Inngår i: Quarterly Journal of the Royal Meteorological Society, ISSN 0035-9009, E-ISSN 1477-870X, Vol. 132, nr 615, 667-680 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An intense low-ozone episode (LOE) was observed over Scandinavia and the North Sea in the middle of August 2003. The LOE occurred under exceptional meteorological conditions, associated with a severe heatwave over Europe. The column ozone minimum for summer (June, July and August) 2003 was reached during the event.

    Using meteorological analyses, satellite ozone observations from the Total Ozone Mapping Spectrometer and the Michelson Interferometer for Passive Atmospheric Sounding aboard the Environment Satellite, we demonstrate that the LOE results from the conjunction of a deep tropospheric blocking over Europe, and a displaced Arctic pool of low-ozone air in the stratosphere, above the anticyclone. The anticyclonic anomaly is part of a Rossby wave train that is apparent throughout the troposphere, and whose influence is felt up to 50 hPa. In the mid-stratosphere (e.g. 30 hPa) long-period westward propagating planetary waves dominate, with a ridge extending over northern Europe in mid-August.

    We band-pass filtered the geopotential field to isolate sub-monthly fluctuations, and calculated three-dimensional wave activity fluxes for quasi-stationary, quasi-geostrophic disturbances embedded in a zonally asymmetric basic state. Results clearly indicate that upward wave fluxes in the lower stratosphere originate from the Atlantic sector, upstream of the maturing blocking.

  • 15. Roldugin, Valentin
    et al.
    Nikulin, Grigory
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Rymdvetenskap.
    Henriksen, Kjell
    Wave-like ozone movements2000Inngår i: Physics and Chemistry of the Earth, Part B: Hydrology, Oceans and Atmosphere, ISSN 1474-7065, Vol. 25, nr 5-6, 511-514 s.Artikkel i tidsskrift (Fagfellevurdert)
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