M. Rapp

Technische Universität München, München, Bavaria, Germany

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Publications (214)278.67 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The EISCAT (European Incoherent SCATer) Scientific Association has provided versatile incoherent scatter (IS) radar facilities on the mainland of northern Scandinavia (the EISCAT UHF and VHF radar systems) and on Svalbard (the electronically scanning radar ESR (EISCAT Svalbard Radar) for studies of the high-latitude ionised upper atmosphere (the ionosphere). The mainland radars were constructed about 30 years ago, based on technological solutions of that time. The science drivers of today, however, require a more flexible instrument, which allows measurements to be made from the troposphere to the topside ionosphere and gives the measured parameters in three dimensions, not just along a single radar beam. The possibility for continuous operation is also an essential feature. To facilitatefuture science work with a world-leading IS radar facility, planning of a new radar system started first with an EU-funded Design Study (2005-2009) and has continued with a follow-up EU FP7 EISCAT_3D Preparatory Phase project (2010-2014). The radar facility will be realised by using phased arrays, and a key aspect is the use of advanced software and data processing techniques. This type of software radar will act as a pathfinder for other facilities worldwide. The new radar facility will enable the EISCAT_3D science community to address new, significant science questions as well as to serve society, which is increasingly dependent on space-based technology and issues related to space weather. The location of the radar within the auroral oval and at the edge of the stratospheric polar vortex is also ideal for studies of the long-term variability in the atmosphere and global change. This paper is a summary of the EISCAT_3D science case, which was prepared as part of the EU-funded Preparatory Phase project for the new facility. Three science working groups, drawn from the EISCAT user community, participated in preparing this document. In addition to these working group members, who are listed as authors, thanks are due to many others in the EISCAT scientific community for useful contributions, discussions, and support.
    11/2015; 2(1). DOI:10.1186/s40645-015-0051-8
  • Journal of Atmospheric and Solar-Terrestrial Physics 04/2015; 127. DOI:10.1016/j.jastp.2015.04.008 · 1.75 Impact Factor
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    ABSTRACT: Sudden stratospheric warmings (SSWs) are the most prominent vertical coupling process in the middle atmosphere, which occur during winter and are caused by the interaction of planetary waves (PWs) with the zonal mean flow. Vertical coupling has also been identified during the equinox transitions, and is similarly associated with PWs. We argue that there is a characteristic aspect of the autumn transition in northern high latitudes, which we call the "hiccup", and which acts like a "mini SSW", i.e. like a small minor warming. We study the average characteristics of the hiccup based on a superimposed epoch analysis using a nudged version of the Canadian Middle Atmosphere Model, representing 30 years of historical data. Hiccups can be identified in about half the years studied. The mesospheric zonal wind results are compared to radar observations over Andenes (69 degrees N, 16 degrees E) for the years 2000-2013. A comparison of the average characteristics of hiccups and SSWs shows both similarities and differences between the two vertical coupling processes.
    Annales Geophysicae 02/2015; 33(2):199-206. DOI:10.5194/angeo-33-199-2015 · 1.68 Impact Factor
  • T. Dunker · U.-P. Hoppe · G. Stober · M. Rapp
    Annales Geophysicae 02/2015; 33(2):197-197. DOI:10.5194/angeo-33-197-2015 · 1.68 Impact Factor
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    ABSTRACT: Annual cycles of horizontal winds and gravity wave (GW) momentum fluxes in the mesosphere and lower thermosphere (MLT) are presented for the medium frequency Doppler radar at Saura (SMF radar, located at 69°N, 16°E) for the first time. 4-year mean wind and momentum flux fields for 2008 through 2011 clearly show the coupling and interactions between GWs and the mean flow especially in the summer months. GW breaking at mesopause heights results in momentum flux divergence and affects the wind field by forcing a reversal of the wind profile in summer. Height-time cross-sections for the individual years (2008 to 2011) illustrate the year-to-year variation of horizontal winds and the vertical fluxes of zonal and meridional momentum. They show similar annual patterns from year to year which are more consistent in the summer months than during winter and have maximum absolute values in 2009. Furthermore, the precise SMF radar measurements give an excellent possibility to evaluate momentum flux estimates from the co-located meteor radar at Andenes. Both radars have different capabilities, and different techniques are applied to derive momentum fluxes. They show comparable results for the 4-year mean annual cycles of horizontal winds and momentum fluxes especially in summer. This holds for both structure and magnitudes in the overlapping heights, where the SMF radar data provides a wider vertical coverage. The best agreement is found for the zonal components of both radars whereas there are some larger discrepancies in the meridional components, especially in the vertical flux of meridional momentum.
    Journal of Geophysical Research: Space Physics 12/2014; 120(1). DOI:10.1002/2014JA020460 · 3.44 Impact Factor
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    ABSTRACT: Meteor smoke particles (MSP), which are thought to be the nucleation germs for mesospheric ice are currently discussed to consist of highly absorbing materials such as magnesiowüstite, hematite or magnesium-iron-silicates and may therefore be warmer than the ambient atmosphere. In order to quantify the temperature difference between MSPs and the atmosphere we developed a model to calculate the MSP equilibrium temperature in radiational and collisonal balance. The temperature difference between MSP and the surrounding atmosphere strongly depends on the composition of the MSP, especially on the relative iron content, where a higher iron content leads to warmer MSP. We then derive an expression of the nucleation rate of mesospheric ice particles which explicitly accounts for this temperature difference. We find that the nucleation rate is strongly reduced by several orders of magnitude if the germ temperature is increased by only a few Kelvin. Implementing this nucleation rate depending on the germ temperature into CARMA, the Community Aerosol and Radiation Model for Atmospheres, we find that fewer but larger ice particles are formed compared to a reference scenario with no temperature difference between MSP and ambient atmosphere. This may indicate that iron-rich MSP are not ideal ice nuclei and that either other MSP-types or other nucleation pathways (e.g. wave induced heterogeneous nucleation or even homogeneous nucleation) are responsible for ice formation at the mesopause.
    Journal of Atmospheric and Solar-Terrestrial Physics 10/2014; 118. DOI:10.1016/j.jastp.2014.03.009 · 1.75 Impact Factor
  • International Dust Conference; 06/2014
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    ABSTRACT: Long-term observations from medium-frequency and meteor radars (1993–2012) and rocket soundings (1979–1990 and 2002–2007) are used to study mesosphere and lower thermosphere (MLT) zonal wind variations in relation to the stratospheric winds over northern low latitudes. The combined data set provides a complete height profile of amplitude of semiannual oscillation (SAO) up to 100 km, with an exception around 75–80 km. The SAO signal has maxima around 50 km and 82 km and a minimum around 65 km. The MLT zonal winds show remarkable interannual variability during northern hemispheric spring equinox and much less during fall equinox. Zonal wind mesospheric spring equinox enhancements (MSEE) appear with a periodicity of 2–3 years, suggesting a modulation by the quasi-biennial oscillation, which we identified with the strength of stratospheric westward winds. Out of 20 years of observations, the stratospheric westward winds are strong during 11 years (non-MSEE) and weak during 9 years. Six of these 9 years show large MLT winds (MSEE), and 3 years (1999, 2004, and 2006) show small MLT winds (missing MSEE). These unexpected small winds occur in years with global circulation anomalies associated with strong sudden stratospheric warmings and an early spring transition of zonal winds. With the proposed three MSEE classes, we take into account local and global forcing factors.
    Journal of Geophysical Research Atmospheres 05/2014; 119(10):5913–5927. DOI:10.1002/2014JD021610 · 3.44 Impact Factor
  • EarthCARE Workshop 2014; 01/2014
  • EarthCARE Workshop 2014; 01/2014
  • Qiang Li · Markus Rapp
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    ABSTRACT: It is now well understood that the occurrence of PMSE is closely connected to the presence of ice particles. These ice particles modify the ambient electron density by electron attachment which occasionally leads to large electron density depletions which have also been called ‘biteouts’. There has been some debate in the literature regarding the relative depth of such depletions which is usually expressed by the parameter Λ=|ZA|NA/neΛ=|ZA|NA/ne. Here, |ZA|NA|ZA|NA is the charge number density of ice particles and ne is the electron density. In this paper, we present, for the first time, the statistical distribution of ΛΛ using measurements with the EISCAT VHF- and UHF-radars. Based on 25 h of simultaneous observations, we derived a total of 757 ΛΛ values based on 15 min of data each. In each of these cases, PMSE were observed with the EISCAT VHF-radar but not with the UHF-radar and the UHF-measurement were hence used to determine the electron density profile. From these 757 cases, there are 699 cases with Λ⪡1Λ⪡1, and only 33 cases with Λ>0.5Λ>0.5 (21 cases with Λ>1Λ>1). A correlation analysis of ΛΛ versus PMSE volume reflectivities further reveals that there is no strong dependence between the two parameters. This is in accordance with current PMSE-theory based on turbulence in combination with a large Schmidt-number. The maxima of ΛΛ from each profile show a negative relationship with the undisturbed electron densities deduced at the same altitudes. This reveals that the variability of ΛΛ mainly depends on the variability of the electron densities. In addition, variations of aerosol number densities may also play a role. Although part of the observations were conducted during the HF heating experiments, the so-called overshoot effects did not significantly bias our statistical results. In order to avoid missing biteouts because of a superposition of coherent and incoherent scatter in the UHF-data, we finally calculated spectral parameters n by applying a simple fit to auto-correlation functions as introduced by Strelnikova and Rapp (2010). Corresponding statistical results of the parameter n indicate that charged ice particles do exist in the vicinity of PMSE (i.e., n<1n<1) but they did not efficiently modify ambient electron densities so that clear ‘biteouts’ are observed.
    Journal of Atmospheric and Solar-Terrestrial Physics 11/2013; 104. DOI:10.1016/j.jastp.2012.10.015 · 1.75 Impact Factor
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    ABSTRACT: The Northern Hemispheric winter is disturbed by large scale variability mainly caused by Planetary Waves (PWs), which interact with the mean flow and thus result in Sudden Stratospheric Warmings (SSWs). The effects of a SSW on the middle atmosphere are an increase of stratospheric and a simultaneous decrease of mesospheric temperature as well as a wind reversal to westward wind from the mesosphere to the stratosphere. In most cases these disturbances are strongest at polar latitudes, get weaker toward the south and vanish at mid-latitudes around 50� to 60� N as for example during the winter 2005/06. However, other events like in 2009, 2010 and 2012 show a similar or even stronger westward wind at mid- than at polar latitudes either in the mesosphere or in the stratosphere during the SSW. This study uses local meteor and MF-radar measurements, global satellite observations from the Microwave Limb Sounder (MLS) and assimilated model data from MERRA (Modern- ERA Retrospective analysis for research and Applications). We compare differences in the latitudinal structure of the zonal wind, temperature and PW activity between a “normal” event, where the event in 2006 was chosen representatively, and the latitudinal displaced events in 2009, 2010 and 2012. A continuous westward wind band between the pole and 20� N is observed during the displaced events. Furthermore, distinctive temperature differences at mid-latitudes occur before the displaced warmings compared to 2006 as well as a southward extended stratospheric warming afterwards. These differences between the normal SSW in 2006 and the displaced events in 2009, 2010 and 2012 are linked to an increased PWactivity between 30� N and 50� N and the changed stationary wave flux in the stratosphere around the displaced events compared to 2006.
    Annales Geophysicae 08/2013; 31:1397--1415. DOI:10.5194/angeo-31-1397-2013 · 1.68 Impact Factor
  • Heiner Asmus · Boris Strelnikov · Markus Rapp
    21st ESA Symposium European Rocket & Balloon Programmes and Related Research, Thun; 06/2013
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    ABSTRACT: From 19 November to 19 December 2010 the fourth and final ECOMA rocket campaign was conducted at Andøya Rocket Range (69° N, 16° E) in northern Norway. We present and discuss measurement results obtained during the last rocket launch labelled ECOMA09 when simultaneous and true common volume in situ measurements of temperature and turbulence supported by ground-based lidar observations reveal two Mesospheric Inversion Layers (MIL) at heights between 71 and 73 km and between 86 and 89 km. Strong turbulence was measured in the region of the upper inversion layer, with the turbulent energy dissipation rates maximising at 2 W kg-1. This upper MIL was observed by the ALOMAR Weber Na lidar over the period of several hours. The spatial extension of this MIL as observed by the MLS instrument onboard AURA satellite was found to be more than two thousand kilometres. Our analysis suggests that both observed MILs could possibly have been produced by neutral air turbulence.
    Annales Geophysicae 05/2013; 31(5):775-785. DOI:10.5194/angeo-31-775-2013 · 1.68 Impact Factor
  • Andreas Dörnbrack · Markus Rapp · Ralph Latteck
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    ABSTRACT: Recently, first three-dimensionally resolved observations of polar mesospheric winter echeos (PMWEs) by a multi-beam experiment of the Middle Atmosphere Alomar Radar system (MAARSY) were published by Rapp et al. (2011). The observed PMWE at about 75 km altitude was tilted in the main flow direction (west to east). The origin of the PMWE was explained by two disparate concepts of gravity wave dynamics. On the one hand, the tilted PMWE was assumed to be aligned with the phase line of a linear gravity wave (?z ? 23 km, ?x ? 460 km) propagating at an intrinsic phase speed of - 73 m/s against the westerly wind. On the other hand, turbulence generated by breaking gravity waves was a necessary element to explain the existence of backscattering fluctuations. In addition to a thorough analysis of the synoptic meteorological conditions, high-resolution numerical simulations are performed with the all-scale geophysical flow solver EULAG (Prusa et al., 2008). The anelastic and pseudo-incompressible approximated equations are solved in a 3D computational domain covers a 1500 km long slice of Scandinavia and spans from the surface to 100 km altitude. Multiple numerical experiments are performed to explore the origin of the observed PMWE. Various hypotheses are tested. The presentation will discuss if the PMWEs were the result of breaking mountain waves excited by the flow over Scandinavia or if dynamical instabilities occuring in the highly sheared mesospheric flow led to the observed turbulence. Rapp, M., R. Latteck, G. Stober, et al., 2011: First three-dimensional observations of polar mesosphere winter echoes: Resolving space-time ambiguity. J. Geophys. Res., 116, A11307, doi:10.1029/2011JA016858. Prusa, J.M., P.K. Smolarkiewicz, A.A. Wyszogrodzki, 2008: EULAG, a computational model for multiscale flows, Comput. Fluids 37, 1193-1207.
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    ABSTRACT: The ECOMA (Existence of Charge state Of meteoric smoke particles in the Middle Atmosphere) sounding rocket campaign was conducted during the Geminid meteor shower in December 2010 in order to explore whether there is a change of the properties of meteoric smoke particles due to the stream. In parallel to the rocket flights, three radars monitored the Geminid activity located at the launch site in Northern Norway and in Northern Germany to gain information about the meteor flux into the atmosphere. The results presented here are based on specular meteor radar observations measuring the radiant position, the velocity and the meteor flux into the atmosphere during the Geminids. Further, the MAARSY (Middle Atmosphere Alomar Radar System) radar was operated to conduct meteor head echo experiments. The interferometric capabilities of MAARSY permit measuring the meteor trajectories within the radar beam and to determine the source radiant and geocentric meteor velocity, as well as to compute the meteor orbit.
    Annales Geophysicae 03/2013; 31(3):473-487. DOI:10.5194/angeo-31-473-2013 · 1.68 Impact Factor
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    ABSTRACT: Three sounding rockets were launched from Andøya Rocket Range in the ECOMA campaign in December 2010. The aim was to study the evolution of meteoric smoke particles during a major meteor shower. Of the various instruments onboard the rocket payload, this paper presents the data from a multi-Needle Langmuir Probe (m-NLP) and a charged dust detector. The payload floating potential, as observed using the m-NLP instrument, shows charging events on two of the three flights. These charging events cannot be explained using a simple charging model, and have implications towards the use of fixed bias Langmuir probes on sounding rockets investigating mesospheric altitudes. We show that for a reliable use of a single fixed bias Langmuir probe as a high spatial resolution relative density measurement, each payload should also carry an additional instrument to measure payload floating potential, and an instrument that is immune to spacecraft charging and measures absolute plasma density.
    Annales Geophysicae 02/2013; 31(2):187-196. DOI:10.5194/angeo-31-187-2013 · 1.68 Impact Factor
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    I. Strelnikova · M. Rapp
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    ABSTRACT: In the present paper ~ 32.5 h of EISCAT VHF PMWE observations were analyzed with focus on spectral properties like spectral width, doppler shift and spectral shape. Examples from two days of observations with weak and strong polar mesosphere winter echo (PMWE) signals are presented and discussed in detail. These examples reveal a large variability from one case to the other. That is, some features like an observed change of vertical wind direction and spectral broadening can be very prominent in one case, but unnoticeable in the other case. However, for all observations a change of spectral shape inside the layer relative to the incoherent background is noticed.
    Annales Geophysicae 02/2013; 31(2):359-375. DOI:10.5194/angeo-31-359-2013 · 1.68 Impact Factor
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    ABSTRACT: Linear gravity wave (GW) theory is tested on the basis of simultaneous measurements of horizontal winds from a medium frequency (MF) radar at Juliusruh (54.6°N, 13.4°E) and temperatures from combined Potassium (K) and Rayleigh-Mie-Raman (RMR) lidars at Kühlungsborn (54.1°N, 11.8°E). The applicability of linear GW theory to mesospheric observations is far from obvious given the fact that typically a whole spectrum of waves is observed which may interact non-linearly. Before analyzing our experimental dataset for its fit to expectations from linear GW theory, the chosen methodology is tested with model data from the Kühlungsborn Mechanistic general Circulation Model (KMCM). This model is a mechanistic general circulation model with high spatial resolution such that waves with horizontal wavelengths in excess of ˜350km are explicitly resolved yielding a semi-realistic wave motion field. This may be considered as a suitable test-bed for defining and optimizing wave analysis approaches. This effort reveals that Stokes parameters analysis of filtered time series of GW-induced wind and temperature fluctuations in comparison to wave amplitudes directly retrieved from the filtered time series allows us to demonstrate the validity of polarization relations based on linear wave theory. Indeed, applying the same methodology to the observations yields similarly conclusive results thus giving evidence for the applicability of linear wave theory to mesospheric observations after appropriate filtering. These investigations are complemented by a comparison of kinetic and potential energy per unit mass for model and measured data. This reveals that the ratio of kinetic and potential energy also roughly follows expectations from linear wave theory.
    Journal of Atmospheric and Solar-Terrestrial Physics 02/2013; 93:57-69. DOI:10.1016/j.jastp.2012.11.012 · 1.75 Impact Factor
  • T. Dunker · U.-P. Hoppe · G. Stober · M. Rapp
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    ABSTRACT: The ECOMA sounding rocket campaign in 2010 was performed to investigate the charge state and number density of meteoric smoke particles during the Geminids meteor shower in December 2010. The ALOMAR Na lidar contributed to the campaign with measurements of sodium number density, temperature and line-of-sight wind between 80 and 110 km altitude over Andøya in northern Norway. This paper investigates a possible connection between the Geminids meteor shower and the mesospheric sodium layer. We compare with data from a meteor radar and from a rocket-borne in situ particle instrument on three days. Our main result is that the sodium column density is smaller during the Geminids meteor shower than the winter average at the same latitude. Moreover, during two of the three years considered, the sodium column density decreased steadily during these three weeks of the year. Both the observed decrease of Na column density by 30% and of meteoric smoke particle column density correlate well with a corresponding decrease of sporadic meteor echoes. We found no correlation between Geminids meteor flux rates and sodium column density, nor between sporadic meteors and Na column density (R = 0.25). In general, we found the Na column density to be at very low values for winter, between 1.8 and 2.6 × 1013 m-2. We detected two meteor trails containing sodium, on 13 December 2010 at 87.1 km and on 19 December 2010 at 84 km. From these meteor trails, we estimate a global meteoric Na flux of 121 kg d-1 and a global total meteoric influx of 20.2 t d-1.
    Annales Geophysicae 01/2013; 31(1):61-73. DOI:10.5194/angeo-31-61-2013 · 1.68 Impact Factor

Publication Stats

2k Citations
278.67 Total Impact Points

Institutions

  • 2013–2015
    • Technische Universität München
      München, Bavaria, Germany
    • University of Oslo
      • Department of Physics
      Kristiania (historical), Oslo, Norway
  • 2014
    • Ludwig-Maximilians-University of Munich
      München, Bavaria, Germany
  • 2009–2013
    • University of Rostock
      Rostock, Mecklenburg-Vorpommern, Germany
  • 1029–2012
    • Leibniz-Institute of Atmospheric Physics
      Rostock, Mecklenburg-Vorpommern, Germany
  • 2005–2006
    • Stockholm University
      • Department of Meteorology (MISU)
      Tukholma, Stockholm, Sweden
  • 2001
    • George Mason University
      • Department of Computational and Data Sciences
      페어팩스, Virginia, United States
  • 1998–1999
    • University of Bonn
      • Physics Institute
      Bonn, North Rhine-Westphalia, Germany