Change search
Refine search result
1 - 19 of 19
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1. Belova, E.
    et al.
    Kirkwood, S.
    Latteck, R.
    Zecha, M.
    Pinedo, H.
    Hedin, Jonas
    Stockholm University, Faculty of Science, Department of Meteorology .
    Gumbel, Jörg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Multi-radar observations of polar mesosphere summer echoes during the PHOCUS campaign on 20-22 July 20112014In: Journal of Atmospheric and Solar-Terrestrial Physics, ISSN 1364-6826, E-ISSN 1879-1824, Vol. 118, p. 199-205Article in journal (Refereed)
    Abstract [en]

    During the PHOCUS rocket campaign, on 20-22 July 2011, the observations of polar mesosphere summer echoes (PMSE) were made by three mesosphere-stratosphere-troposphere radars, operating at about 50 MHz. One radar, ESRAD is located at Esrange in Sweden, where the rocket was launched, two other radars, MAARSY and MORRO, are located 250 km north-west and 200 km north of the ESRAD, respectively, on the other side of the Scandinavian mountain ridge. We compared PMSE as measured by these three radars in terms of their strength, spectral width and wave modulation. Time-altitude maps of PMSE strength look very similar for all three radars. Cross-correlations with maximum values 0.5-0.6 were found between the signal powers over the three days of observations for each pair of radars. By using cross-spectrum analysis of PMSE signals, we show that some waves with periods of a few hours were observed by all three radars. Unlike the strengths, simultaneous values of PMSE spectral width, which is related to turbulence, sometimes differ significantly between the radars. For interpretation of the results we suggested that large-scale fields of neutral temperature, ice particles and electron density, which are more or less uniform over 150-250 km horizontal extent were 'modulated' by waves and smaller patches of turbulence.

  • 2. Dawkins, E. C. M.
    et al.
    Plane, J. M. C.
    Chipperfield, M. P.
    Feng, W.
    Gumbel, Jörg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Hedin, Jonas
    Stockholm University, Faculty of Science, Department of Meteorology .
    Höffner, J.
    Friedman, J. S.
    First global observations of the mesospheric potassium layer2014In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 41, no 15, p. 5653-5661Article in journal (Refereed)
    Abstract [en]

    Metal species, produced by meteoric ablation, act as useful tracers of upper atmosphere dynamics and chemistry. Of these meteoric metals, K is an enigma: at extratropical latitudes, limited available lidar data show that the K layer displays a semiannual seasonal variability, rather than the annual pattern seen in other metals such as Na and Fe. Here we present the first near-global K retrieval, where K atom number density profiles are derived from dayglow measurements made by the Optical Spectrograph and Infrared Imager System spectrometer on board the Odin satellite. This robust retrieval produces density profiles with typical layer peak errors of 15% and a 2km vertical grid resolution. We demonstrate that these retrieved profiles compare well with available lidar data and show for the first time that the unusual semiannual behavior is near-global in extent. This new data set has wider applications for improving understanding of the K chemistry and of related upper atmosphere processes.

  • 3. Enell, Carl-Fredrik
    et al.
    Hedin, Jonas
    Stockholm University, Faculty of Science, Department of Meteorology .
    Stegman, Jacek
    Stockholm University, Faculty of Science, Department of Meteorology .
    Witt, Georg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Friedrich, Martin
    Singer, Werner
    Baumgarten, Gerd
    Kaifler, Bernd
    Hoppe, Ulf-Peter
    Gustavsson, Björn
    Brandström, Urban
    Khaplanov, Mikhail
    Stockholm University, Faculty of Science, Department of Meteorology .
    Kero, Antti
    Ulich, Thomas
    Turunen, Esa
    The Hotel Payload 2 campaign: Overview of NO, O and electron density measurements in the upper mesosphere and lower thermosphere2011In: Journal of Atmospheric and Solar-Terrestrial Physics, ISSN 1364-6826, E-ISSN 1879-1824, Vol. 73, no 14-15, p. 2228-2236Article in journal (Refereed)
    Abstract [en]

    The ALOMAR eARI Hotel Payload 2 (HotPay 2) rocket campaign took place at Andoya Rocket Range, Norway, in January 2008. The rocket was launched on January 31, 2008 at 19:14 UT, when auroral activity appeared after a long geomagnetically quiet period. In this paper we present an overview of the HotPay 2 measurements of upper mesospheric and lower thermospheric (UMLT) electron, atomic oxygen (O) and nitric oxide (NO) densities. [O] and [NO] were retrieved from a set of three photometers, Night-Time Emissions from the Mesosphere and Ionosphere (NEMI). Faraday rotation receivers on the rocket and the EISCAT UHF incoherent scatter radar provided simultaneous electron density profiles, whereas the ALOMAR Na lidar and meteor radar measured the temperature profile and wind. The aurora was also observed with ground-based imagers. The retrieved oxygen number density profile has a maximum at 89 km, some 10 km lower than expected from earlier measurements and modelled profiles based on climatological averages (such as the MSIS model), and the retrieved NO densities are also lower than the expected. Satellite measurements indicate that subsidence over the winter pole controlled the densities. Quantitative chemistry model results based on climatological average atmospheric density and temperature profiles were, therefore, not in good agreement with the measured profiles. The Hotel Payload 2 measurements thus confirm the importance of downward transport from the thermosphere into the winter polar vortex.

  • 4. Guineva, V.
    et al.
    Witt, Georg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Gumbel, Jörg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Khaplanov, Mikhail
    Stockholm University, Faculty of Science, Department of Meteorology .
    Werner, R.
    Hedin, Jonas
    Stockholm University, Faculty of Science, Department of Meteorology .
    Neichev, S.
    Kirov, B.
    Bankov, L.
    Gramatikov, P.
    Tashev, V.
    Popov, M.
    Hauglund, K.
    Hansen, G.
    Ilstad, J.
    Wold, H.
    O-2 density and temperature profiles retrieving from direct solar Lyman-alpha radiation measurements2009In: Geomagnetism and Aeronomy, ISSN 0016-7932, E-ISSN 1555-645X, Vol. 49, no 8, p. 1292-1295Article in journal (Refereed)
    Abstract [en]

    The resonance transition P-2-S-2 of the atomic hydrogen (Lyman-alpha emission) is the strongest and most conspicuous feature in the solar EUV spectrum. The Lyman-alpha radiation transfer depends on the resonance scattering from the hydrogen atoms in the atmosphere and on the O-2 absorption. Since the Lyman-alpha extinction in the atmosphere is a measure for the column density of the oxygen molecules, the atmospheric O-2 density and temperature profiles can be calculated thereof. A detector of solar Lyman-alpha radiation was manufactured in the Stara Zagora Department of the Solar-Terrestrial Influences Laboratory (STIL). Its basic part is an ionization camera, filled in with NO. A 60 V power supply is applied to the chamber. The produced photoelectric current from the sensor is fed to a two-channel amplifier, providing analog signal. The characteristics of the Lyman-alpha detector were studied. It passed successfully all tests and the results showed that the so-designed instrument could be used in rocket experiments to measure the Lymanalpha flux. From the measurements of the detector, the Lyman-alpha vertical profile can be obtained. Programs are created to compute the O-2 density, atmospheric power and temperature profiles based on Lymanalpha data. The detector design appertained to ASLAF project (Attenuation of the Solar Lyman-Alpha Flux), a scientific cooperation between STIL-Bul.Acad.Sci., Stara Zagora Department and the Atmospheric Physics Group at the Department of Meteorology (MISU), Stockholm University, Sweden. The joint project was part of the rocket experiment HotPay I, in the ALOMAR eARI Project, EU's 6th Framework Programme, Andoya Rocket Range, Andenes, Norway. The project is partly financed by the Bulgarian Ministry of Science and Education.

  • 5. Havnes, O.
    et al.
    Gumbel, Jörg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Antonsen, T.
    Hedin, Jonas
    Stockholm University, Faculty of Science, Department of Meteorology .
    La Hoz, C.
    On the size distribution of collision fragments of NLC dust particles and their relevance to meteoric smoke particles2014In: Journal of Atmospheric and Solar-Terrestrial Physics, ISSN 1364-6826, E-ISSN 1879-1824, Vol. 118, p. 190-198Article in journal (Refereed)
    Abstract [en]

    We present the results from a new dust probe MUDD on the PHOCUS payload which was launched in July 2011. In the interior of MUDD all the incoming NLC/PMSE icy dust particles will collide, at an impact angle similar to 70 degrees to the surface normal, with a grid constructed such that no dust particles can directly hit the bottom plate of the probe. Only collision fragments will continue down towards the bottom plate. We determine an energy distribution of the charged fragments by applying a variable electric field between the impact grid and the bottom plate of MUDD. We find that similar to 30% of the charged fragments have kinetic energies less than 10 eV, similar to 20% have energies between 10 and 20 eV while similar to 50% have energies above 20 eV. The transformation of limits in kinetic energy for ice or meteoric smoke particles (MSP) to radius is dependent on many assumptions, the most crucial being fragment velocity. We find, however, that the sizes of the charged fragments most probably are in the range of 1 to 2 nm if meteoric smoke particles (MSP), and slightly higher if ice particles. The observed high charging fraction and the dominance of fragment sizes below a few nm makes it very unlikely that the fragments can consist mainly of ice but that they must be predominantly MSP as predicted by Havnes and N ae sheim (2007) and recently observed by Hervig et al. (2012). The MUDD results indicate that MSP are embedded in NLC/PMSE ice particles with a minimum volume filling factor of similar to.05% in the unlikely case that all embedded MSP are released and charged. A few % volume filling factor (Hervig et al., 2012) can easily be reached if similar to 10% of the MSP are released and that their charging probability is similar to 0.1.

  • 6.
    Hedin, Jonas
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Giovane, Frank
    Waldemarsson, Tomas
    Stockholm University, Faculty of Science, Department of Meteorology . Naval Research Laboratory, USA.
    Gumbel, Jörg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Blum, Jürgen
    Stroud, Rhonda M.
    Marlin, Layne
    Moser, John
    Siskind, David E.
    Jansson, Kjell
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Saunders, Russell W.
    Summers, Michael E.
    Reissaus, Philipp
    Stegman, Jacek
    Stockholm University, Faculty of Science, Department of Meteorology .
    Plane, John M. C.
    Horanyi, Mihaly
    The MAGIC meteoric smoke particle sampler2014In: Journal of Atmospheric and Solar-Terrestrial Physics, ISSN 1364-6826, E-ISSN 1879-1824, Vol. 118, p. 127-144Article in journal (Refereed)
    Abstract [en]

    Between a few tons to several hundred tons of meteoric material enters the Earth's atmosphere each day, and most of this material is ablated and vaporized in the 70-120 km altitude region. The subsequent chemical conversion, re-condensation and coagulation of this evaporated material are thought to form nanometre sized meteoric smoke particles (MSPs). These smoke particles are then subject to further coagulation, sedimentation and global transport by the mesospheric circulation. MSPs have been proposed as a key player in the formation and evolution of ice particle layers around the mesopause region, i.e. noctilucent clouds (NLC) and polar mesosphere summer echoes (PMSE). MSPs have also been implicated in mesospheric heterogeneous chemistry to influence the mesospheric odd oxygen/odd hydrogen (O-x/HOx) chemistry, to play an important role in the mesospheric charge balance, and to be a significant component of stratospheric aerosol and enhance the depletion of O-3. Despite their apparent importance, little is known about the properties of MSPs and none of the hypotheses can be verified without direct evidence of the existence, altitude and size distribution, shape and elemental composition. The aim of the MAGIC project (Mesospheric Aerosol - Genesis, Interaction and Composition) was to develop an instrument and analysis techniques to sample for the first time MSPs in the mesosphere and return them to the ground for detailed analysis in the laboratory. MAGIC meteoric smoke particle samplers have been flown on several sounding rocket payloads between 2005 and 2011. Several of these flights concerned non-summer mesosphere conditions when pure MSP populations can be expected. Other flights concerned high latitude summer conditions when MSPs are expected to be contained in ice particles in the upper mesosphere. In this paper we present the MAGIC project and describe the MAGIC MSP sampler, the measurement procedure and laboratory analysis. We also present the attempts to retrieve MSPs from these flights, the challenges inherent to the sampling of nanometre sized particles and the subsequent analysis of the sampled material, and thoughts for the future. Despite substantial experimental efforts, the MAGIC project has so far failed to provide conclusive results. While particles with elemental composition similar to what is to be expected from MSPs have been found, the analysis has been compromised by challenges with different types of contamination and uncertainties in the sticking efficiency of the particles on the sampling surfaces.

  • 7.
    Hedin, Jonas
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Gumbel, Jörg
    Stockholm University, Faculty of Science, Department of Meteorology .
    The global mesospheric sodium layer observed by Odin/OSIRIS in 2004-20092011In: Journal of Atmospheric and Solar-Terrestrial Physics, ISSN 1364-6826, E-ISSN 1879-1824, Vol. 73, no 14-15, p. 2221-2227Article in journal (Refereed)
    Abstract [en]

    The source of the mesospheric sodium layer is the daily ablation of 10-100 tons of meteoric material in Earth's atmosphere. Global studies of this layer yield important information about the chemistry and dynamics of Earth's mesosphere and lower thermosphere (MLT). For nine years the Optical Spectrograph and Infra-Red Imager System (OSIRIS) on-board the Odin satellite has observed Earth's middle atmosphere by limb measurements of scattered sunlight from the ultraviolet to the infrared. In its aeronomy mode, Odin performs limb scans during 15 near-polar sun-synchronous orbits each day. The current measurement programme provides scans up to 110 km on about 300 days per year. Above 70 km, Na D resonance scattering at 589 nm results in a strong limb signal. Retrievals from this dayglow feature have provided a global database of the mesospheric sodium layer. We present an updated sodium climatology from the Odin mission, including latitudinal and seasonal dependence, and interannual variability. We find a weak seasonal variation at low latitudes and an annual variation at mid- and high-latitudes with a clear summer minimum. An interesting feature is an interhemispheric asymmetry in the global dataset with larger sodium abundances during fall in the northern hemisphere and during spring in the southern hemisphere.

  • 8.
    Hedin, Jonas
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Gumbel, Jörg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Khaplanov, Mikhail
    Stockholm University, Faculty of Science, Department of Meteorology .
    Witt, Georg
    Stegman, Jacek
    Stockholm University, Faculty of Science, Department of Meteorology .
    Optical studies of noctilucent clouds in the extreme ultraviolet2008In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 26, no 5, p. 1109-1119Article in journal (Refereed)
    Abstract [en]

    In order to better understand noctilucent clouds (NLC) and their sensitivity to the variable environment of the polar mesosphere, more needs to be learned about the actual cloud particle population. Optical measurements are today the only means of obtaining information about the size of mesospheric ice particles. In order to efficiently access particle sizes, scattering experiments need to be performed in the Mie scattering regime, thus requiring wavelengths of the order of the particle size. Previous studies of NLC have been performed at wavelengths down to 355 nm from the ground and down to about 200 nm from rockets and satellites. However, from these measurements it is not possible to access the smaller particles in the mesospheric ice population. This current lack of knowledge is a major limitation when studying important questions about the nucleation and growth processes governing NLC and related particle phenomena in the mesosphere. We show that NLC measurements in the extreme ultraviolet, in particular using solar Lyman-α radiation at 121.57 nm, are an efficient way to further promote our understanding of NLC particle size distributions. This applies both to global measurements from satellites and to detailed in situ studies from sounding rockets. Here, we present examples from recent rocket-borne studies that demonstrate how ambiguities in the size retrieval at longer wavelengths can be removed by invoking Lyman-α. We discuss basic requirements and instrument concepts for future rocket-borne NLC missions. In order for Lyman-α radiation to reach NLC altitudes, high solar elevation and, hence, daytime conditions are needed. Considering the effects of Lyman-α on NLC in general, we argue that the traditional focus of rocket-borne NLC missions on twilight conditions has limited our ability to study the full complexity of the summer mesopause environment.

  • 9.
    Hedin, Jonas
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Gumbel, Jörg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Rapp, Markus
    On the efficiency of rocket-borne particle detection in the mesosphere2007In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 7, no 14, p. 3701-3711Article in journal (Refereed)
    Abstract [en]

    Meteoric smoke particles have been proposed as a key player in the formation and evolution of mesospheric phenomena. Despite their apparent importance still very little is known about these particles. Important questions concern the smoke number density and size distribution as a function of altitude as well as the fraction of charged particles. Sounding rockets are used to measure smoke in situ, but aerodynamics has remained a major challenge. Basically, the small smoke particles tend to follow the gas flow around the payload rather than reaching the detector if aerodynamics is not considered carefully in the detector design. So far only indirect evidence for the existence of meteoric smoke has been available from measurements of heavy charge carriers. Quantitative ways are needed that relate these measured particle population to the atmospheric particle population. This requires in particular knowledge about the size-dependent, altitude-dependent and charge-dependent detection efficiency for a given instrument. In this paper, we investigate the aerodynamics for a typical electrostatic detector design. We first quantify the flow field of the background gas, then introduce particles in the flow field and determine their trajectories around the payload structure. We use two different models to trace particles in the flow field, a Continuous motion model and a Brownian motion model. Brownian motion is shown to be of basic importance for the smallest particles. Detection efficiencies are determined for three detector designs, including two with ventilation holes to allow airflow through the detector. Results from this investigation show that rocket-borne smoke detection with conventional detectors is largely limited to altitudes above 75 km. The flow through a ventilated detector has to be relatively large in order to significantly improve the detection efficiency.

  • 10.
    Hedin, Jonas
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Gumbel, Jörg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Stegman, Jacek
    Stockholm University, Faculty of Science, Department of Meteorology .
    Witt, Georg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Use of O2 airglow for calibrating direct atomic oxygen measurements from sounding rockets2009In: Atmospheric Measurement Techniques, ISSN 1867-1381, Vol. 2, p. 801-812Article in journal (Refereed)
    Abstract [en]

    Accurate knowledge about the distribution of atomic oxygen is crucial for many studies of the mesosphere and lower thermosphere. Direct measurements of atomic oxygen by the resonance fluorescence technique at 130 nm have been made from many sounding rocket payloads in the past. This measurement technique yields atomic oxygen profiles with good sensitivity and altitude resolution. However, accuracy is a problem as calibration and aerodynamics make the quantitative analysis challenging. Most often, accuracies better than a factor 2 are not to be expected from direct atomic oxygen measurements. As an example, we present results from the NLTE (Non Local Thermodynamic Equilibrium) sounding rocket campaign at Esrange, Sweden, in 1998, with simultaneous O2 airglow and O resonance fluorescence measurements. O number densities are found to be consistent with the nightglow analysis, but only within the uncertainty limits of the resonance fluorescence technique. Based on these results, we here describe how better atomic oxygen number densities can be obtained by calibrating direct techniques with complementary airglow photometer measurements and detailed aerodynamic analysis. Night-time direct O measurements can be complemented by photometric detection of the O2 (b1g+X3g-) Atmospheric Band at 762 nm, while during daytime the O2 (a1ΔgX3g-) Infrared Atmospheric Band at 1.27 μm can be used. The combination of a photometer and a rather simple resonance fluorescence probe can provide atomic oxygen profiles with both good accuracy and good height resolution.

  • 11.
    Hedin, Jonas
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Gumbel, Jörg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Waldemarsson, Tomas
    Stockholm University, Faculty of Science, Department of Meteorology .
    Giovane, Frank
    Naval Research Laboratory, Washington, DC.
    The aerodynamics of the MAGIC meteoric smoke sampler2007In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 40, no 6, p. 818-824Article in journal (Refereed)
    Abstract [en]

    The detection of nanometre-sized meteoric smoke particles in the Earth’s mesosphere and lower thermosphere is difficult. The particles are too small for optical detection and so far only the charged fraction of the particles has been probed by rocket-borne instruments. One way to obtain maximum information about the smoke particles is direct sampling with rocket-borne particle samplers. The MAGIC project (Mesospheric Aerosol – Genesis, Interaction and Composition) aims to quantitatively answer fundamental questions about the properties of smoke in the atmosphere. The first launch of such particle samplers was performed during the MAGIC rocket campaign from Esrange, Sweden, in January 2005. In order to characterise the sampling process, we have performed simulations of the trajectories of nanometre-sized dust particles towards the MAGIC detectors with a new particle motion model. An important feature of this model is the Brownian motion of the particles due to thermal collisions of the gas molecules. As a result, we obtain the detection efficiency for the MAGIC detectors as a function of altitude and particle size. Our simulations confirm that particles of radii down to 0.75 nm impact on the sampling surface with an efficiency exceeding 80% over the entire mesospheric altitude range of interest.

  • 12.
    Hedin, Jonas
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Rapp, Markus
    Deutsches Zentrum für Luft und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany.
    Khaplanov, Mikhail
    Stockholm University, Faculty of Science, Department of Meteorology .
    Stegman, Jacek
    Stockholm University, Faculty of Science, Department of Meteorology .
    Witt, Georg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Observations of NO in the upper mesosphere and lower thermosphere during ECOMA 20102012In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 30, p. 1611-1621Article in journal (Refereed)
    Abstract [en]

    In December 2010 the last campaign of the German-Norwegian sounding rocket project ECOMA (Existence and Charge state Of Meteoric smoke particles in the middle Atmosphere) was conducted from Andøya Rocket Range in northern Norway (69° N, 16° E) in connection with the Geminid meteor shower. The main instrument on board the rocket payloads was the ECOMA detector for studying meteoric smoke particles (MSPs) by active photoionization and subsequent detection of the produced charges (particles and photoelectrons). In addition to photoionizing MSPs, the energy of the emitted photons from the ECOMA flash-lamp is high enough to also photoionize nitric oxide (NO). Thus, around the peak of the NO layer, at and above the main MSP layer, photoelectrons produced by the photoionization of NO are expected to contribute to, or even dominate above the main MSP-layer, the total measured photoelectron current. Among the other instruments on board was a set of two photometers to study the O2(b1Σg+X3Σg-) Atmospheric band and NO2 continuum nightglow emissions. In the absence of auroral emissions, these two nightglow features can be used together to infer NO number densities. This will provide a way to quantify the contribution of NO photoelectrons to the photoelectron current measured by the ECOMA instrument and, above the MSP layer, a simultaneous measurement of NO with two different and independent techniques. This work is still on-going due to the uncertainties, especially in the effort to quantitatively infer NO densities from the ECOMA photoelectron current, and the lack of simultaneous measurements of temperature and density for the photometric study. In this paper we describe these two techniques to infer NO densities and discuss the uncertainties. The peak NO number density inferred from the two photometers on ascent was 3.9 × 108 cm−3 at an altitude of about 99 km, while the concentration inferred from the ECOMA photoelectron measurement at this altitude was a factor of 5 smaller.

  • 13. Kalogerakis, Konstantinos S.
    et al.
    Matsiev, Daniel
    Cosby, Philip C.
    Dodd, James A.
    Falcinelli, Stefano
    Hedin, Jonas
    Stockholm University, Faculty of Science, Department of Meteorology .
    Kutepov, Alexander A.
    Noll, Stefan
    Panka, Peter A.
    Romanescu, Constantin
    Thiebaud, Jérôme E.
    New insights for mesospheric OH: multi-quantum vibrational relaxation as a driver for non-local thermodynamic equilibrium2018In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 36, no 1, p. 13-24Article in journal (Refereed)
    Abstract [en]

    The question of whether mesospheric OH(v) rotational population distributions are in equilibrium with the local kinetic temperature has been debated over several decades. Despite several indications for the existence of non-equilibrium effects, the general consensus has been that emissions originating from low rotational levels are thermalized. Sky spectra simultaneously observing several vibrational levels demonstrated reproducible trends in the extracted OH(v) rotational temperatures as a function of vibrational excitation. Laboratory experiments provided information on rotational energy transfer and direct evidence for fast multi-quantum OH(high-v) vibrational relaxation by O atoms. We examine the relationship of the new relaxation pathways with the behavior exhibited by OH(v) rotational population distributions. Rapid OH(high-v) + O multi-quantum vibrational relaxation connects high and low vibrational levels and enhances the hot tail of the OH(low-v) rotational distributions. The effective rotational temperatures of mesospheric OH(v) are found to deviate from local thermodynamic equilibrium for all observed vibrational levels. Dedicated to Tom G. Slanger in celebration of his 5 decades of research in aeronomy.

  • 14. Plane, John M. C.
    et al.
    Saunders, Russell W.
    Hedin, Jonas
    Stockholm University, Faculty of Science, Department of Meteorology .
    Stegman, Jacek
    Stockholm University, Faculty of Science, Department of Meteorology .
    Khaplanov, Misha
    Stockholm University, Faculty of Science, Department of Meteorology .
    Gumbel, Jörg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Lynch, Kristina A.
    Bracikowski, Phillip J.
    Gelinas, Lynette J.
    Friedrich, Martin
    Blindheim, Sandra
    Gausa, Michael
    Williams, Bifford P.
    A combined rocket-borne and ground-based study of the sodium layer and charged dust in the upper mesosphere2014In: Journal of Atmospheric and Solar-Terrestrial Physics, ISSN 1364-6826, E-ISSN 1879-1824, Vol. 118, p. 151-160Article in journal (Refereed)
    Abstract [en]

    The Hotel Payload 2 rocket was launched on January 31st 2008 at 20.14 LT from the Andoya Rocket Range in northern Norway (69.31 degrees N, 16.01 degrees E). Measurements in the 75-105 km region of atomic O, negatively-charged dust, positive ions and electrons with a suite of instruments on the payload were complemented by lidar measurements of atomic Na and temperature from the nearby ALOMAR observatory. The payload passed within 2.58 km of the lidar at an altitude of 90 km. A series of coupled models is used to explore the observations, leading to two significant conclusions. First, the atomic Na layer and the vertical profiles of negatively-charged dust (assumed to be meteoric smoke particles), electrons and positive ions, can be modelled using a self-consistent meteoric input flux. Second, electronic structure calculations and Rice-Ramsperger-Kassel-Markus theory are used to show that even small Fe-Mg-silicates are able to attach electrons rapidly and form stable negatively-charged particles, compared with electron attachment to O-2 and O-3. This explains the substantial electron depletion between 80 and 90 km, where the presence of atomic O at concentrations in excess of 10(10) cm(-3) prevents the formation of stable negative ions.

  • 15.
    Rapp, Markus
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Hedin, Jonas
    Stockholm University, Faculty of Science, Department of Meteorology .
    Strelnikova, Irina
    Friedrich, Martin
    Gumbel, Jörg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Lübken, Franz-Josef
    Observations of positively charged nanoparticles in the nighttime polar mesosphere2005In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 32, p. L23821-Article in journal (Refereed)
    Abstract [en]

    We present results of in situ measurements of charged nanoparticles, electrons, and positive ions obtained during a sounding rocket flight in October 2004 from Kiruna, Sweden, under nighttime conditions. The particle measurement reveals positive charge signatures in the altitude range between 80 and 90 km corresponding to peak charge number densities of ∼100 e/cm3 at around 86 km. Aerodynamical analysis of the sampling efficiency of our instrument reveals that the particles must have been larger than 2 nm assuming spherical particles with a density of 3 g/cm3. The plasma environment of the observed particles is dominated by negative and positive ions, with only few free electrons. A calculation of the mean particle charge expected for particles in a plasma consisting of electrons and positive and negative ions shows that the presence of sufficiently heavy and numerous negative ions (i.e., m n > 300 amu and λ ≥ 50) can explain the observed positive particle charge.

  • 16.
    Rapp, Markus
    et al.
    Deutsches Zentrum für Luft und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany.
    Plane, J. M. C.
    School of Chemistry, University of Leeds, UK.
    Strelnikov, B.
    Leibnitz-Institut of Atmospheric Physics, Kühlungsborn, Germany.
    Stober, G.
    Leibnitz-Institut of Atmospheric Physics, Kühlungsborn, Germany.
    Ernst, S.
    Leibnitz-Institut of Atmospheric Physics, Kühlungsborn, Germany.
    Hedin, Jonas
    Stockholm University, Faculty of Science, Department of Meteorology .
    Friedrich, M.
    Graz University of Technology, Austria.
    Hoppe, U.-P-
    University of Oslo, Department of Physics, Norway.
    In situ observations of meteor smoke particles (MSP) during the Geminids 2010: contraints on MSP size, work function and composition2012In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 30, p. 1611-1622Article in journal (Refereed)
  • 17. Sternovsky, Z.
    et al.
    Robertson, S.
    Dickson, S.
    Gumbel, Jörg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Hedin, Jonas
    Stockholm University, Faculty of Science, Department of Meteorology .
    Strelnikov, B.
    Asmus, H.
    Havnes, O.
    In-situ detection of noctilucent cloud particles by the Colorado Dust Detectors onboard the PHOCUS sounding rocket2014In: Journal of Atmospheric and Solar-Terrestrial Physics, ISSN 1364-6826, E-ISSN 1879-1824, Vol. 118, p. 145-150Article in journal (Refereed)
    Abstract [en]

    The Particles, Hydrogen and Oxygen Chemistry in the Upper Summer mesosphere (PHOCUS) sounding rocket campaign is a payload that carried multiple in-situ instruments for the detection of charged icy particles of noctilucent clouds (NLCs). The PHOCUS payload was launched on July 21st, 2011 and carried 18 scientific instruments. Three of these instruments were dedicated to the detection of the charged aerosol particles. All three instruments detected a narrow ice layer at around 81.5 km altitude. The Colorado Dust Detectors (CDDs) collected the net charge from the impact of aerosol particles on two graphite surfaces mounted flush with the payload skin. A combination of a small bias potential and permanent magnets were used to suppress the collection of plasma particles. The efficiency of the magnetic shielding improves with increasing altitude where there are fewer scattering collisions with neutrals. The data analysis shows that the net collected current can be decomposed into contributions from photoelectron emission, plasma electrons and ions, and the aerosol particles. The results show that the current corresponding to the collection of aerosol particles is positive, which is due to secondary charging effects.

  • 18. Strelnikov, Boris
    et al.
    Szewczyk, Artur
    Strelnikova, Irina
    Latteck, Ralph
    Baumgarten, Gerd
    Lubken, Franz-Josef
    Rapp, Markus
    Fasoulas, Stefanos
    Lohle, Stefan
    Eberhart, Martin
    Hoppe, Ulf-Peter
    Dunker, Tim
    Friedrich, Martin
    Hedin, Jonas
    Stockholm University, Faculty of Science, Department of Meteorology .
    Khaplanov, Mikhail
    Stockholm University, Faculty of Science, Department of Meteorology .
    Gumbel, Jörg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Barjatya, Aroh
    Spatial and temporal variability in MLT turbulence inferred from in situ and ground-based observations during the WADIS-1 sounding rocket campaign2017In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 35, no 3, p. 547-565Article in journal (Refereed)
    Abstract [en]

    In summer 2013 the WADIS-1 sounding rocket campaign was conducted at the Andoya Space Center (ACS) in northern Norway (69 degrees N, 16 degrees E). Among other things, it addressed the question of the variability in mesosphere/lower thermosphere (MLT) turbulence, both in time and space. A unique feature of the WADIS project was multi-point turbulence sounding applying different measurement techniques including rocket-borne ionization gauges, VHF MAARSY radar, and VHF EISCAT radar near Tromso. This allowed for horizontal variability to be observed in the turbulence field in the MLT at scales from a few to 100 km. We found that the turbulence dissipation rate, epsilon varied in space in a wavelike manner both horizontally and in the vertical direction. This wavelike modulation reveals the same vertical wavelengths as those seen in gravity waves. We also found that the vertical mean value of radar observations of epsilon agrees reasonably with rocket-borne measurements. In this way defined <epsilon(radar)> value reveals clear tidal modulation and results in variation by up to 2 orders of magnitude with periods of 24 h. The <epsilon(radar)> value also shows 12 h and shorter (1 to a few hours) modulations resulting in one decade of variation in <epsilon(radar)> magnitude. The 24 h modulation appeared to be in phase with tidal change of horizontal wind observed by SAURA-MF radar. Such wavelike and, in particular, tidal modulation of the turbulence dissipation field in the MLT region inferred from our analysis is a new finding of this work.

  • 19. Tsuda, T. T.
    et al.
    Nakamura, T.
    Ejiri, M. K.
    Nishiyama, T.
    Hosokawa, K.
    Takahashi, T.
    Gumbel, Jörg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Hedin, Jonas
    Stockholm University, Faculty of Science, Department of Meteorology .
    Statistical investigation of Na layer response to geomagnetic activity using resonance scattering measurements by Odin/OSIRIS2017In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 44, no 12, p. 5943-5950Article in journal (Refereed)
    Abstract [en]

    We have performed a statistical investigation of the global response of the Na layer to geomagnetic activity using Na density data from 2004 to 2010 obtained using the Optical Spectrograph and Infrared Imager System (OSIRIS) on board the Odin satellite. In the analysis, we categorized the Na density data according to the auroral electrojet (AE) index and then compared the resulting data sets. Regarding the results, we found a significant decrease in the Na density above a height of similar to 95 km in both the southern and northern polar regions with an increase in the AE index. The cause of the decrease in the Na density is discussed, and we conclude that the decrease in the Na density was mainly due to the effect of energetic particle precipitation.

1 - 19 of 19
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf