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  • 1.
    Ehard, Benedikt
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Achtert, Peggy
    Stockholm University, Faculty of Science, Department of Meteorology . Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Gumbel, Jörg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Long-term lidar observations of wintertime gravity wave activity over northern Sweden2014In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 32, no 11, p. 1395-1405Article in journal (Refereed)
    Abstract [en]

    This paper presents an analysis of gravity wave activity over northern Sweden as deduced from 18 years of wintertime lidar measurements at Esrange (68ºN, 21ºE). Gravity wave potential energy density (GWPED) was used to characterize the strength of gravity waves in the altitude regions 30–40km and 40–50 km. The obtained values ex- ceed previous observations reported in the literature. This is suggested to be due to Esrange’s location downwind of the Scandinavian mountain range and due to differences in the various methods that are currently used to retrieve gravity wave parameters. The analysis method restricted the identification of the dominating vertical wavelengths to a range from 2 to 13 km. No preference was found for any wavelength in this window. Monthly mean values of GW- PED show that most of the gravity waves’ energy dissipates well below the stratopause and that higher altitude regions show only small dissipation rates of GWPED. Our analy- sis does not reproduce the previously reported negative trend in gravity wave activity over Esrange. The observed inter-annual variability of GWPED is connected to the occurrence of stratospheric warmings with generally lower wintertime mean GWPED during years with major stratospheric warmings. A bimodal GWPED occurrence frequency indicates that gravitywave activity at Esrange is affected by both ubiq- uitous wave sources and orographic forcing.

  • 2.
    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.

  • 3.
    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.

  • 4. 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.

  • 5.
    Megner, Linda
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Khaplanov, Mikhail
    Stockholm University, Faculty of Science, Department of Meteorology .
    Baumgarten, G.
    Leibniz-Institute of Atmospheric Physics.
    Gumbel, Jörg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Stegman, Jacek
    Stockholm University, Faculty of Science, Department of Meteorology .
    Strelnikov, B.
    Leibniz-Institute of Atmospheric Physics.
    Robertson, S.
    University of Colorado. Department of Physics .
    Large mesospheric ice particles at exceptionally high altitudes2009In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 27, p. 943-951Article in journal (Refereed)
    Abstract [en]

    We here report on the characteristics of exceptionally high Noctilucent clouds (NLC) that were detected with rocket photometers during the ECOMA/MASS campaign at Andøya, Norway 2007. The results from three separate flights are shown and discussed in connection to lidar measurements. Both the lidar measurements and the large difference between various rocket passages through the NLC show that the cloud layer was inhomogeneous on large scales. Two passages showed a particularly high, bright and vertically extended cloud, reaching to approximately 88 km. Long time series of lidar measurements show that NLC this high are very rare, only one NLC measurement out of thousand reaches above 87 km. The NLC is found to consist of three distinct layers. All three were bright enough to allow for particle size retrieval by phase function analysis, even though the lowest layer proved too horizontally inhomogeneous to obtain a trustworthy result. Large particles, corresponding to an effective radius of 50 nm, were observed both in the middle and top of the NLC. The present cloud does not comply with the conventional picture that NLC ice particles nucleate near the temperature minimum and grow to larger sizes as they sediment to lower altitudes. Strong up-welling, likely caused by gravity wave activity, is required to explain its characteristics.

  • 6.
    Rapp, M.
    et al.
    Leibniz Institute for Atmospheric Physics.
    Strelnikova, I.
    Leibniz Institute for Atmospheric Physics.
    Strelnikov, B.
    Leibniz Institute for Atmospheric Physics.
    Latteck, R.
    Leibniz Institute for Atmospheric Physics.
    Baumgarten, G.
    Leibniz Institute for Atmospheric Physics.
    Li, Q.
    Leibniz Institute for Atmospheric Physics.
    Megner, Linda
    Stockholm University, Faculty of Science, Department of Meteorology .
    Gumbel, Jörg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Friedrich, M.
    Graz University of Technology. Institute of Communication Networks and Satellite Communications.
    Hoppe, U.-P.
    Norwegian Defence Research Establishment (FFI), .
    Robertson, S.
    University of Colorado. Department of Physics.
    First in situ measurement of the vertical distribution of ice volume in a mesospheric ice cloud during the ECOMA/MASS rocket-campaign2009In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, no 27, p. 755-766Article in journal (Refereed)
    Abstract [en]

    We present in situ observations of mesospheric ice particles with a new particle detector which combines a classical Faraday cup with the active photoionization of particles and subsequent detection of photoelectrons. Our observations of charged particles and free electrons within a decaying PMSE-layer reveal that the presence of charged particles is a necessary but not sufficient condition for the presence of PMSE. That is, additional requirements like a sufficiently large electron density – which we here estimate to be on the order of ~100 cm−3 – and the presence of small scale structures (commonly assumed to be caused by turbulence) need to be satisfied. Our photoelectron measurements reveal a very strong horizontal structuring of the investigated ice layer, i.e., a very broad layer (82–88 km) seen on the upleg is replaced by a narrow layer from 84.5–86 km only 50 km apart on the downleg of the rocket flight. Importantly, the qualitative structure of these photoelectron profiles is in remarkable qualitative agreement with photometer measurements on the same rocket thus demonstrating the reliability of this new technique. We then show that the photoelectron currents are a unique function of the ice particle volume density (and hence ice mass) within an uncertainty of only 15% and we derive corresponding altitude profiles of ice volume densities. Derived values are in the range ~2–8×10−14 cm3/cm3 (corresponding to mass densities of ~20–80 ng/m3, and water vapor mixing ratios of 3–12 ppm) and are the first such estimates with the unique spatial resolution of an in situ measurement.

  • 7.
    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)
  • 8.
    Robertson, S.
    et al.
    University of Colorado. Laboratory for Atmospheric and Space Physics.
    Horányi, M.
    University of Colorado. Laboratory for Atmospheric and Space Physics.
    Knappmiller, S.
    University of Colorado. Laboratory for Atmospheric and Space Physics.
    Sternovsky, Z.
    University of Colorado. Laboratory for Atmospheric and Space Physics.
    Holzworth, R.
    University of Washington. Earth and Space Sciences.
    Shimogawa, M.
    University of Washington. Earth and Space Sciences.
    Friedrich, M.
    Graz University of Technology. Institute of Communication Networks and Satellite Communications.
    Torkar, K.
    Austrian Academy of Sciences. Space Research Institute.
    Gumbel, Jörg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Megner, Linda
    Stockholm University, Faculty of Science, Department of Meteorology .
    Baumgarten, G.
    Leibniz Institute for Atmospheric Physics.
    Latteck, R.
    Leibniz Institute for Atmospheric Physics.
    Rapp, M.
    Leibniz Institute for Atmospheric Physics.
    Hoppe, U.-P.
    Norwegian Defence Research Establishment (FFI), .
    Hervig, M. E.
    GATS, Inc.
    Mass analysis of charged aerosol particles in NLC and PMSE during the ECOMA/MASS campaign2009In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, no 27, p. 1213-1232Article in journal (Refereed)
    Abstract [en]

    MASS (Mesospheric Aerosol Sampling Spectrometer) is a multichannel mass spectrometer for charged aerosol particles, which was flown from the Andøya Rocket Range, Norway, through NLC and PMSE on 3 August 2007 and through PMSE on 6 August 2007. The eight-channel analyzers provided for the first time simultaneous measurements of the charge density residing on aerosol particles in four mass ranges, corresponding to ice particles with radii <0.5 nm (including ions), 0.5–1 nm, 1–2 nm, and >3 nm (approximately). Positive and negative particles were recorded on separate channels. Faraday rotation measurements provided electron density and a means of checking charge density measurements made by the spectrometer. Additional complementary measurements were made by rocket-borne dust impact detectors, electric field booms, a photometer and ground-based radar and lidar. The MASS data from the first flight showed negative charge number densities of 1500–3000 cm−3 for particles with radii >3 nm from 83–88 km approximately coincident with PMSE observed by the ALWIN radar and NLC observed by the ALOMAR lidar. For particles in the 1–2 nm range, number densities of positive and negative charge were similar in magnitude (~2000 cm−3) and for smaller particles, 0.5–1 nm in radius, positive charge was dominant. The occurrence of positive charge on the aerosol particles of the smallest size and predominately negative charge on the particles of largest size suggests that nucleation occurs on positive condensation nuclei and is followed by collection of negative charge during subsequent growth to larger size. Faraday rotation measurements show a bite-out in electron density that increases the time for positive aerosol particles to be neutralized and charged negatively. The larger particles (>3 nm) are observed throughout the NLC region, 83–88 km, and the smaller particles are observed primarily at the high end of the range, 86–88 km. The second flight into PMSE alone at 84–88 km, found only small number densities (~500 cm−3) of particles >3 nm in a narrow altitude range, 86.5–87.5 km. Both positive (~2000 cm−3) and negative (~4500 cm−3) particles with radii 1–2 nm were detected from 85–87.5 km.

  • 9. 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.

  • 10.
    Tjernström, Michael
    Stockholm University, Faculty of Science, Department of Meteorology .
    A study of flow over complex terrain using a three-dimensional model1987In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 5, p. 469-486Article in journal (Refereed)
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