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Sample records for matter polar mesosphere

  1. Detecting Aerosols in the Polar Mesosphere

    NASA Astrophysics Data System (ADS)

    Robertson, S.; Sternovsky, Z.; Horanyi, M.

    2005-12-01

    Two instruments have been developed to detect charged aerosol particles in the mesosphere. The first is a flat charge collecting graphite surface on the skin of the rocket that has returned data in several sounding rocket campaigns. The collection surfaces have permanent magnets behind them to provide shielding from electrons. Some of the probes also have an electrical bias to repel light positive ions. Two probes, one with and one without an electric bias, have been launched in January 2005 from Esrange, Sweden, as a part of the MAGIC campaign. The probes have detected a distinct layer of aerosols at around 82 km altitude. The second instrument has been developed to detect charged, sub-visible aerosol particles in the upper atmosphere. The instrument is designed to fly on a sounding rocket and has a 30 square centimeter entrance slit. Venting ports are placed lower on the detector in order to let the air out and reduce pressure buildup inside the detector. The air sample flows between four pairs of graphite electrodes biased symmetrically with increasing bias potentials. Electrons, light ions, cluster ions and heavy charged aerosol particles of both polarities are collected mass-selectively on the electrodes that are connected to sensitive electrometers. Direct Simulation Monte Carlo (DSMC) codes have been used to optimize the supersonic airflow within and around the instrument. A laboratory prototype of the instrument has been fabricated and calibrated using low energy ion beams. The instrument is scheduled for launch in the summer of 2007 from Andoya, Norway. These in-situ measurements are planned to coincide with the Aeronomy of Ice in the Mesosphere (AIM) mission. Acknowledgement: The project is supported by NASA.

  2. Measuring the Polar Mesosphere With Radio Telescopes

    NASA Astrophysics Data System (ADS)

    Martin, C. L.; Burrows, S. M.

    2004-12-01

    The 1957 IGY launched a program of upper atmosphere observations that continues to this day. However in 1957, observations of the upper atmosphere were limited to the tools available at the time. As we head toward the 2007 IPY we can take advantage of the tools developed in the past 50 years to continue and expand upon this extensive dataset, as well as consider novel uses for the tools already available on the continent. Over the past ten years, the polar plateau has been established as one of the preeminent sites on Earth from which to perform radio astronomy observations at frequencies ranging from 100 to 2000 GHz. As a by-product of their astronomical observations, these telescopes often collect high quality aeronomy data that is frequently overlooked. By using data from a radio telescope located at the Amundsen-Scott South Pole Station, we have measured the J=2 -> 1 (230 GHz), J=4-> 3 (461 GHz), and J=7 -> 6 (807 GHz) rotational transitions of carbon monoxide (CO) at altitudes from 50 to 90 km above the Earth's surface. These high frequency data provide a surprisingly high resolution window into the dynamics and structure of the mesosphere. With a time series extending over multiple years, these data allow us to study the dynamics of an altitude range difficult to access with other methods. The IPY provides us with an opportunity to expand these interdisciplinary collaborations and use the resources invested in the Antarctic continent to further the scientific aims of a broad range of researchers.

  3. Dusty plasma processes in Earth's polar summer mesosphere

    NASA Astrophysics Data System (ADS)

    Popel, S. I.; Dubinsky, A. Yu.; Dubinsky

    2013-08-01

    A self-consistent model for the description of dusty plasma structures, such as noctilucent clouds (NLC) and polar mesosphere summer echoes (PMSE), which are frequently grouped together under the common term polar mesospheric clouds, is presented. The model takes into account the processes of condensation of water vapor, ionization, recombination, action of solar radiation, sedimentation, dust particle growth, dust particle charging, electric fields, etc. Using the model, we explain the basic data of observations on the behavior of charged component in polar summer mesosphere. Furthermore, we show the influence of initial distributions of fine particles as well as that of the processes of condensation and water molecule absorption by fine particles on the formation of NLC and PMSE. We also illustrate the possibility of the formation of layered structure and sharp boundaries of NLC.

  4. NLC-91: An experimental study of the polar summer mesosphere

    NASA Technical Reports Server (NTRS)

    Goldberg, R. A.; Kopp, E.; Witt, G.

    1994-01-01

    In the summer of 1991, a major scientific campaign (NLC-91) involving 31 rocket flights was conducted from ESRANGE, Kiruna, Sweden and from Heiss Island, Russia to investigate the chemical, dynamical, and electrodynamical properties of the polar summer mesosphere. The rocket flights were also coordinated with two coherent radar facilities, EISCAT (European Incoherent Scatter Scientific Association) and CUPRI (Cornell University Portable Radar Instrument), as well as other ground facilities, to provide continual monitoring of the mesosphere by remote sensing techniques. The primary objectives of the campaign were to study noctilucent clouds (NLC's) and polar mesospheric summer echoes (PMSE's), including their possible relationship to local aerosols and/or small scale turbulence. The program involved scientific participation from eight countries, and promises to produce many results during the next few years. This overview considers the scientific campaign and briefly discusses preliminary results. These results are provided in more detail in papers following this overview.

  5. NLC-91: An experimental study of the polar summer mesosphere

    NASA Technical Reports Server (NTRS)

    Goldberg, R. A.; Kopp, E.; Witt, G.

    1994-01-01

    In the summer of 1991, a major scientific campaign (NLC-91) involving 31 rocket flights was conducted from ESRANGE, Kiruna, Sweden and from Heiss Island, Russia to investigate the chemical, dynamical, and electrodynamical properties of the polar summer mesosphere. The rocket flights were also coordinated with two coherent radar facilities, EISCAT (European Incoherent Scatter Scientific Association) and CUPRI (Cornell University Portable Radar Instrument), as well as other ground facilities, to provide continual monitoring of the mesosphere by remote sensing techniques. The primary objectives of the campaign were to study noctilucent clouds (NLC's) and polar mesospheric summer echoes (PMSE's), including their possible relationship to local aerosols and/or small scale turbulence. The program involved scientific participation from eight countries, and promises to produce many results during the next few years. This overview considers the scientific campaign and briefly discusses preliminary results. These results are provided in more detail in papers following this overview.

  6. Polar mesosphere summer echoes (PMSE) a southern hemisphere perspective

    NASA Astrophysics Data System (ADS)

    Morris, R. J.; Murphy, D. J.; Klekociuk, A. R.; Holdsworth, D. A.

    The existence of Polar Mesosphere Summer Echoes PMSE in the Southern Hemisphere SH has recently been confirmed using HF radar Ogawa et al 2002 MST radar Morris et al 2004 and a Dynasonde Jarvis et al 2005 following earlier observations using MST radar Woodman et al 1999 These studies spanned the geographic latitudes 62 1 r S Machu Picchu 68 6 r S Davis 69 0 r S Syowa and 75 5 r S Halley Bay The emerging array of SH SuperDARN radars provide an opportunity to extend the spatial coverage of PMSE observations An understanding of the occurrence and intensity of PMSE against latitude in the SH is needed to facilitate a comparison with the better spatial coverage of Northern Hemisphere NH PMSE observations Such a comparison will contribute to the ongoing debate as to whether PMSE can provide a proxy for mesosphere temperature and thus shed light on the existence of any interhemispheric asymmetry or otherwise in the polar mesosphere regions The argument for different polar mesosphere environments spawned in part by the reported lack of SH PMSE observations Recent PMSE reflectivity and intensity results from Davis 68 6 r S and Andenes 69 0 r N are given The characteristics and morphology of PMSE events above these Antarctic stations are considered in the context of the thermal and dynamical state of the mesosphere as deduced from satellite i e SABER and AURA and radar i e MF and MST observations respectively A brief account of recent coincident PMSE MST radar and Polar Mesospheric Cloud PMC

  7. Investigating seasonal gravity wave activity in the summer polar mesosphere

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Taylor, M. J.; Randall, C. E.; Lumpe, J. D.; Siskind, D. E.; Bailey, S. M.; Russell, J. M.

    2015-05-01

    The NASA Aeronomy of Ice in the Mesosphere (AIM) satellite is the first spaceborne mission dedicated to studying high-altitude (~83 km) Polar Mesospheric Clouds (PMCs). Since its launch in 2007, the Cloud Imaging and Particle Size (CIPS) instrument onboard AIM has obtained large-field, high resolution (25 km2/pixel) images of the PMCs, enabling a unique investigation of mesospheric gravity wave activity in the summer polar mesosphere where previous measurements have been sparse. In this study, we have analyzed 12 consecutive seasons of AIM/CIPS PMC albedo data to determine the statistical properties of medium and large horizontal scale (>100 km) gravity waves present in the PMC data. Over 60,000 wave events with horizontal scale-sizes ranging up to >2000 km have been identified and measured, revealing a wealth of wave events particularly in the ~300-800 km range where our analysis sensitivity is largest. These data are ideal for investigating the intra-seasonal, inter-annual and hemispheric variability of these waves as observed over the whole summer polar cap regions. Throughout this 6 year study, the wave activity in the southern hemisphere was found to be consistently 10-15% higher than in the northern hemisphere and both the northern and southern hemisphere wave activity was determined to decrease systematically (by ~15%) during the course of each summer season. This decrease agrees well with previous seasonal stratospheric studies of variations in the wave energy, suggesting a direct influence of the lower atmospheric sources on polar mesospheric dynamics. Very similar and consistent results were also found from season to season in both hemispheres providing new information for gravity wave modeling and dynamical studies of the high-latitude summer-time mesosphere.

  8. Long-term changes of (polar) mesosphere summer echoes

    NASA Astrophysics Data System (ADS)

    Bremer, J.; Hoffmann, P.; Latteck, R.; Singer, W.; Zecha, M.

    2009-10-01

    Strong VHF radar echoes have been observed not only during summer months at polar latitudes (polar mesosphere summer echoes, PMSE) but also at middle latitudes (mesosphere summer echoes, MSE). These echoes are closely connected with small ice particles, thus containing information about mesospheric temperature and water vapour content. But the (P)MSE also depend on the ionisation due to solar wave radiation and precipitating high energetic particles. Observations with VHF radars at Andenes (69.3°N; 16.0°E) since 1994 and at Kühlungsborn (54.6°N; 11.8°E) since 1998 are used for investigations of the solar and geomagnetic control of the (P)MSE as well as of possible long-term changes. The (P)MSE are positively correlated with the solar Lyman [alpha] radiation and the geomagnetic activity and have slightly positive trends. Due to the limited measuring period, the significance levels of the detected (P)MSE trends are small. Positive trends in noctilucent clouds (NLC) and polar mesospheric clouds (PMC) are in general agreement with (P)MSE trends.

  9. Kinetics of ice particles growth in the polar summer mesosphere

    NASA Astrophysics Data System (ADS)

    Zasetsky, A. Y.; Petelina, S. V.

    2009-05-01

    The growth kinetics of ice particles in the polar summer mesosphere is discussed. The particle growth time is calculated using the temperature, water vapor density, and ice number density simultaneously measured by the infrared Fourier Transform Spectrometer on the Atmospheric Chemistry Experiment (ACE-FTS) satellite. The formation rate for ice particles is a very strong function of temperature and water vapor concentration. We found the equilibrium radius of ice particles to be in the range from 20 to 70 nm, and the formation time - from about 2 hours at 150 K to about 18 hours at 125 K. Our results imply that in addition to the commonly accepted particle growth during their sedimentation from higher altitudes, in-situ growth to radii of 50-70 nm at mesospheric temperatures near 150 K in two hours or less may also be possible. Our analysis of possible shapes for mesospheric ice particles using the band shape of ice absorption feature measured by ACE-FTS suggests that cubes or compact hexagonal prisms (with an aspect ratio of 1.1) are the best candidates to represent the crystalline ice particles in the polar summer mesosphere.

  10. Power spectra of mesospheric velocities in polar regions

    NASA Technical Reports Server (NTRS)

    Czechowsky, P.; Ruster, R.

    1985-01-01

    The mobile SOUSY radar was operated on Andoya in Northern Norway during the MAP/WINE campaign from November 1983 to February 1984 and for about two weeks in June 1984 to study the seasonal dependence of mesospheric structures and dynamics at polar latitudes. During the winter period, measurements were carried out on 57 days, primarily in coordination with the schedule of the rocket experiments. Echoes were detected in the troposphere and stratosphere up to 30 km and at mesospheric heights from about 50 to 90 km with a distinct maximum around noon. In summer, the radar system was operated continuously from 19th to the 28th of June 1984. Echoes occurred almost for 24 hours in the height range from 70 to 95 km showing no recognizable diurnal variation. Similar observations in polar latitudes were carried out for several years with the Poker Flat Radar in Alaska.

  11. Power spectra of mesospheric velocities in polar regions

    NASA Technical Reports Server (NTRS)

    Czechowsky, P.; Ruster, R.

    1985-01-01

    The mobile SOUSY radar was operated on Andoya in Northern Norway during the MAP/WINE campaign from November 1983 to February 1984 and for about two weeks in June 1984 to study the seasonal dependence of mesospheric structures and dynamics at polar latitudes. During the winter period, measurements were carried out on 57 days, primarily in coordination with the schedule of the rocket experiments. Echoes were detected in the troposphere and stratosphere up to 30 km and at mesospheric heights from about 50 to 90 km with a distinct maximum around noon. In summer, the radar system was operated continuously from 19th to the 28th of June 1984. Echoes occurred almost for 24 hours in the height range from 70 to 95 km showing no recognizable diurnal variation. Similar observations in polar latitudes were carried out for several years with the Poker Flat Radar in Alaska.

  12. Charged questions concerning noctilucent clouds and polar mesospheric summer echoes

    NASA Astrophysics Data System (ADS)

    Gumbel, J.

    2012-12-01

    Noctilucent clouds (NLC) and polar mesosphere summer echoes (PMSE) are prominent phenomena related to ice layers in the Earth's atmosphere at 80-90 km. These phenomena have been recognized as important tracers for interactions and variability in this part of the atmosphere. In order to draw proper conclusions from global observations, a better understanding of the microphysics of mesospheric ice grains is needed. This presentation provides an overview of current research topics concerning NLC and PMSE, with an emphasis is on charging pocesses. NLC and PMSE coincide with the ionospheric D-region, thus constituting a weakly ionized dusty plasma. Prominent open questions concern the efficiency of charge capture and photoionization, the role of charges in ice nucleation, charge diffusion, and interactions between ice and meteoric material.

  13. Radar scattering from the summer polar mesosphere: Theory and observations

    NASA Astrophysics Data System (ADS)

    Cho, John Yungdo Nagamichi

    1993-12-01

    The anomalously large radar reflectivities observed in the summer polar mesosphere have eluded satisfactory explanation until now. We propose that the following chain of causality is responsible for the so-called polar mesosphere summer echoes (PMSE): The uniquely low temperatures in the summer mesopause produce ice aerosols. Because the aerosols exist in a plasma, they become electrically charged. The ambient electrons become coupled to the aerosols through electric fields and their effective diffusivity is retarded due to the large size of the aerosols. The reduction in diffusivity allows electron density inhomogeneities to be maintained at the radar Bragg scales. The radar waves are then scattered by the inhomogeneities. We support the above concept by developing a quantitative theory of ambipolar diffusion in the mesosphere. We then apply the results to isotropic turbulence and Fresnel radar scatter to show that the observed radar reflectivities can be explained by the theory. We show that the presence of realistic charged aerosols are sufficient to explain PMSE. We also show that dressed aerosol radar scatter, proposed by others as a generation mechanism for PMSE, can only apply to echoes detected by UHF radars. We present data taken with the Sondrestrom 1.29-GHz radar and attribute it to dressed aerosol scatter. In the summer of 1991, we used the Cornell University portable radar interferometer (CUPRI) to observe the mesosphere while rockets carrying in situ sensors were flown through two PMSE occurrences and a noctilucent cloud/PMSE event. We present a selection of first results from this campaign (NLC-91). The first simultaneous height comparison between noctilucent clouds and PMSE show that the radar scattering region was near or slightly above the visible cloud layer. We also infer from aspect sensitivity measurements and Doppler spectrograms that there were two distinct types of PMSE: enhanced turbulent scatter and partial (Fresnel) reflection from steep

  14. PoSSUM: Polar Suborbital Science in the Upper Mesosphere

    NASA Astrophysics Data System (ADS)

    Reimuller, J. D.; Fritts, D. C.; Thomas, G. E.; Taylor, M. J.; Mitchell, S.; Lehmacher, G. A.; Watchorn, S. R.; Baumgarten, G.; Plane, J. M.

    2013-12-01

    Project PoSSUM (www.projectpossum.org) is a suborbital research project leveraging imaging and remote sensing techniques from Reusable Suborbital Launch Vehicles (rSLVs) to gather critical climate data through use of the PoSSUM Observatory and the PoSSUM Aeronomy Laboratory. An acronym for Polar Suborbital Science in the Upper Mesosphere, PoSSUM grew from the opportunity created by the Noctilucent Cloud Imagery and Tomography Experiment, selected by the NASA Flight Opportunities Program as Experiment 46-S in March 2012. This experiment will employ an rSLV (e.g. the XCOR Lynx Mark II) launched from a high-latitude spaceport (e.g. Eielson AFB, Alaska or Kiruna, Sweden) during a week-long deployment scheduled for July 2015 to address critical questions concerning noctilucent clouds (NLCs) through flights that transition the cloud layer where the clouds will be under direct illumination from the sun. The 2015 Project PoSSUM NLC campaign will use the unique capability of rSLVs to address key under-answered questions pertaining to NLCs. Specifically, PoSSUM will answer: 1) What are the small-scale dynamics of NLCs and what does this tell us about the energy and momentum deposition from the lower atmosphere? 2) What is the seasonal variability of NLCs, mesospheric dynamics, and temperatures? 3) Are structures observed in the OH layer coupled with NLC structures? 4) How do NLCs nucleate? and 5) What is the geometry of NLC particles and how do they stratify? Instrumentation will include video and still-frame visible cameras (PoSSUMCam), infrared cameras, a mesospheric temperatures experiment, a depolarization LiDAR, a mesospheric density and temperatures experiment (MCAT), a mesospheric winds experiment, and a meteoric smoke detector (MASS). The instrument suite used on PoSSUM will mature through subsequent campaigns to develop an integrated, modular laboratory (the ';PoSSUM Observatory') that will provide repeatable, low cost, in-situ NLC and aeronomy observations as well

  15. The Influence of Planetary Waves on Polar Mesospheric Clouds

    NASA Astrophysics Data System (ADS)

    France, J. A.; Randall, C. E.; Harvey, L.; Siskind, D. E.; Lumpe, J. D.; Bailey, S. M.; Carstens, J. N.; Russell, J. M., III

    2016-12-01

    Polar mesospheric clouds (PMCs) form as a result of low temperatures and enhanced water vapor near the polar summer mesospause. These conditions occur as a result of upwelling associated with the upper branch of the gravity wave-driven global residual circulation, and are sensitive to changes in planetary wave breaking in the winter hemisphere through interhemispheric coupling (IHC). Observations by the Cloud Imaging and Particle Size (CIPS) instrument on the Aeronomy of Ice in the Mesosphere (AIM) satellite show an anomalous decline in northern hemisphere PMCs in August 2014. The decline is attributed to IHC triggered by planetary wave activity in the Antarctic stratosphere. The results indicate that the IHC in 2014 occurred via a pathway that previous studies have not emphasized. Based on Aura Microwave Limb Sounder data, we suggest that shifts in zonal winds in the summer stratosphere triggered a circulation change that led to the observed PMC decline. We also show that the 5-day planetary wave modulates the response to IHC, in that PMCs persist in the trough when zonal mean temperatures are too high to support PMCs, and are absent in the ridge when mean temperatures are low enough to support PMCs.

  16. Five-day Waves in Polar Stratosphere and Mesosphere Temperature and Mesospheric Ice Water Measured by SOFIE/AIM

    NASA Astrophysics Data System (ADS)

    Yue, J.; Liu, X.

    2015-12-01

    The temperature and column ice water content (IWC) of polar mesospheric clouds (PMCs) have been simultaneously measured by the Solar Occultation for Ice Experiment (SOFIE) onboard NASA's Aeronomy of Ice in the Mesosphere (AIM) satellite since April 2007. The 8-year (2007-2014) data of the temperature and IWC are used to extract the 5-day planetary waves (PWs) with zonal wavenumbers ranging from -1 to -3 (eastward propagating mode, E1-E3), 0 (stationary mode, W0), and 1 to 3 (westward propagating mode, W1-W3) in the polar stratosphere and mesosphere. The 5-day PWs in temperature are stronger in the polar winter stratosphere and mesosphere and exhibit substantial inter-hemispheric asymmetry. The date-height distributions of the 5-day waves coincide with those of the eastward jet in each hemisphere. This indicates that the 5-day PWs might be generated from barotropic/baroclinic instability in the polar stratosphere. The relative strengths of 5-day PWs decrease with increasing wavenumbers. The E1 (W1) 5-day PW is stronger than any other mode in the winter stratosphere and lower mesosphere (summer upper mesosphere). SOFIE temperature and IWC data are derived from simultaneous measurements in the same air column and thus provide a good opportunity to study the phase relationship between the 5-day PWs in temperature and IWC. Our analyses show that the phase shifts of W1 5-day PW in temperature relative to that in IWC have a mean of -2.0 h (0.3 h) with a standard deviation of 3.8 h (4.2 h) in the northern (southern) polar region. This indicates that the formation of the W1 5-day PW in PMCs is controlled mainly by the W1 5-day PW in temperature and influenced by other factors and is consistent with previous studies.

  17. Five-day waves in polar stratosphere and mesosphere temperature and mesospheric ice water measured by SOFIE/AIM

    NASA Astrophysics Data System (ADS)

    Liu, Xiao; Yue, Jia; Xu, Jiyao; Yuan, Wei; Russell, James M., III; Hervig, Mark E.

    2015-05-01

    The temperature and column ice water content (IWC) of polar mesospheric clouds (PMCs) have been simultaneously measured by the Solar Occultation for Ice Experiment (SOFIE) on board NASA's Aeronomy of Ice in the Mesosphere satellite since April 2007. The 8 year (2007-2014) data of the temperature and IWC are used to extract the 5 day planetary waves (PWs) with zonal wave numbers ranging from -1 to -3 (eastward propagating mode, E1-E3), 0 (stationary mode, W0), and 1 to 3 (westward propagating mode, W1-W3) in the polar stratosphere and mesosphere. The 5 day PWs in temperature are stronger in the polar winter stratosphere and mesosphere and exhibit substantial interhemispheric asymmetry. The date-height distributions of the 5 day waves coincide with those of the eastward jet in each hemisphere. This indicates that the 5 day PWs might be generated from barotropic/baroclinic instability in the polar stratosphere. The relative strengths of 5 day PWs decrease with increasing wave numbers. The E1 (W1) 5 day PW is stronger than any other mode in the winter stratosphere and lower mesosphere (summer upper mesosphere). SOFIE temperature and IWC data are derived from simultaneous measurements in the same air column and thus provide a good opportunity to study the phase relationship between the 5 day PWs in temperature and IWC. Our analyses show that the phase shifts of W1 5 day PW in temperature relative to that in IWC have a mean of -2.0 h (0.3 h) with a standard deviation of 3.8 h (4.2 h) in the northern (southern) polar region. This indicates that the formation of the W1 5 day PW in PMCs is controlled mainly by the W1 5 day PW in temperature and influenced by other factors and is consistent with previous studies.

  18. Radar Scattering from the Summer Polar Mesosphere: Theory and Observations

    NASA Astrophysics Data System (ADS)

    Cho, John Yungdo Nagamichi

    The anomalously large radar reflectivities observed in the summer polar mesosphere have eluded satisfactory explanation until now. We propose that the following chain of causality is responsible for the so-called polar mesosphere summer echoes (PMSE): The uniquely low temperatures in the summer mesopause produce ice aerosols. Because the aerosols exist in a plasma, they become electrically charged. The ambient electrons become coupled to the aerosols through electric fields and their effective diffusivity is retarded due to the large size of the aerosols. The reduction in diffusivity allows electron density inhomogeneities to be maintained at the radar Bragg scales. The radar waves are then scattered by the inhomogeneities. We support the above concept by developing a quantitative theory of ambipolar diffusion in the mesosphere. We then apply the results to isotropic turbulence and Fresnel radar scatter to show that the observed radar reflectivities can be explained by the theory. We show that the presence of realistic charged aerosols are sufficient to explain PMSE. We also show that dressed aerosol radar scatter, proposed by others as a generation mechanism for PMSE, can only apply to echoes detected by UHF radars. We present data taken with the Sondrestrom 1.29-GHz radar, which we believe to be the first PMSE event observed above one gigahertz, and attribute it to dressed aerosol scatter. In the summer of 1991, we used the Cornell University portable radar interferometer (CUPRI) to observe the mesosphere while rockets carrying in situ sensors were flown through two PMSE occurrences and a noctilucent cloud/PMSE event. We present a selection of first results from this campaign (NLC-91). The first simultaneous height comparison between noctilucent clouds and PMSE show that the radar scattering region was near or slightly above the visible cloud layer. We also infer from aspect sensitivity measurements and Doppler spectrograms that there were two distinct types of

  19. The PHOCUS Project: Particle Interactions in the Polar Summer Mesosphere

    NASA Astrophysics Data System (ADS)

    Gumbel, J.; Hedin, J.; Khaplanov, M.

    2012-12-01

    On the morning of July 21, 2011, the PHOCUS sounding rocket was launched from Esrange, Sweden, into strong noctilucent clouds (NLC) and polar mesosphere summer echoes (PMSE) observed by the Esrange lidar and the ESRAD MST radar. The aim of the PHOCUS project (Particles, Hydrogen and Oxygen Chemistry in the Upper Summer mesosphere) is to study mesospheric particles (ice and meteoric smoke) and their interaction with their neutral and charged environment. Starting out from first ideas in 2005, PHOCUS has developed into a comprehensive venture that connects to a number of new and renewed scientific questions. Interactions of interest comprise the charging and nucleation of particles, the relationship between meteoric smoke and ice, and the influence of these particles on gas-phase chemistry. This presentation gives an overview of the campaign and scientific results. The backbone of the campaign was a sounding rocket with 18 instruments from 8 scientific groups in Sweden, Norway, Germany, Austria and the USA. Atmospheric composition and ice particle properties were probed by a set of optical instruments from Stockholm University, in collaboration with the University in Trondheim. Exciting new instrument developments concerned microwave radiometers for in situ measurements of water vapour at 183 and 558 GHz by Chalmers University of Technology. Charged particles were probed by impact detectors from the University of Colorado, the University of Tromsø and the Leibniz Institute of Atmospheric Physics (IAP), complemented by direct particle sampling from Stockholm University. The neutral and charged background state of the atmosphere was quantified by the Technical University Graz, IAP, and the Norwegian Defence Research Establishment. Important ground-based instrumentation included the Esrange lidar, the ESRAD MST radar, the SkiYMET meteor radar and EISCAT.

  20. Using polar mesosphere summer echoes and stratospheric/mesospheric winds to explain summer mesopause jumps in Antarctica

    NASA Astrophysics Data System (ADS)

    Lübken, Franz-Josef; Latteck, Ralph; Becker, Erich; Höffner, Josef; Murphy, Damian

    2017-09-01

    Recent high resolution temperature measurements by resonance lidar occasionally showed a sudden mesopause altitude increase by ∼5 km and an associated mesopause temperature decrease by ∼10 K at Davis (69°S). In this paper we present further observations which are closely related to this 'mesopause jump', namely the increase of mean height of polar mesospheric summer echoes (PMSE) observed by a VHF radar, very strong westward winds in the upper mesosphere measured by an MF radar, and relatively large eastward winds in the stratosphere taken from reanalysis. We present a detailed explanation of mesopause jumps. They occur only when stratospheric winds are moderately eastward and mesospheric winds are strongly westward. Under these conditions, gravity waves with comparatively large eastward phase speeds can pass the stratosphere and propagate to the lower thermosphere because their vertical wavelengths in the mesosphere are rather large which implies enhanced dynamical stability. When finally breaking in the lower thermosphere, these waves drive an enhanced residual circulation that causes a cold and high-altitude mesopause. The conditions for a mesopause jump occur only in the Southern Hemisphere (SH) and are associated with the late breakdown of the polar vortex. Mesopause jumps are primarily, but not only, observed prior and close to solstice. Our study also shows that during the onset of PMSE in the SH, stratospheric zonal winds are still eastward (up to 30 m/s), and that the onset is not closely related to the transition of the stratospheric circulation. Unlike previously published results with polar mesospheric clouds, we find an overall poor correlation between PMSE onset and the date of the vortex breakdown.

  1. Radar Observations and Dynamics of the Polar Summer Mesosphere.

    NASA Astrophysics Data System (ADS)

    Hall, Timothy Mather

    The lowest temperatures and the highest clouds on Earth, complex ion chemistry, large amplitude waves, and intense radar scatter make the summer polar mesosphere a fascinating atmospheric region. In this work, we tackle two puzzles of the region related to radar echoing and detection: the role of the Stokes drift in measurements of the seasonal circulation, and the extension of the electron density variance spectrum to length scales smaller than those of the driving turbulence. Although the mass flux rate at the summer polar mesopause must be about 1 cm/s upward to be consistent with the temperature, radars measure 20 to 30 cm/s downward (Balsley and Riddle 1984; Meek and Manson, 1989). We have verified this surprising result with four years of radar data, the longest analysis performed to date. Coy et al. (1986) argue that the Stokes drift associated with acoustic-gravity waves can resolve this discrepancy by inducing an Eulerian mean velocity opposite to the mass flux rate. However, for a reliable estimate of this Stokes drift effect, the calculation must include a realistic spectrum of waves. In this work, after discussing the Stokes drift in detail, we generalize the calculation to include such a spectrum. The results indicate that the Stokes drift is not large enough to explain the radar measurements. As an alternative, eve suggest the radar is detecting the fall speed of charged aerosols. Structuring of the polar summer mesospheric electron density at scales shorter than the inner scale of turbulence is necessary to explain the intensity of VHF radar echoes. As the second major topic of this work, we describe a combined rocket-radar experiment measuring simultaneous mesopause region profiles of the electron diffusive-inner scale and the turbulence inner scale. The results imply a reduction in the effective diffusion coefficient at least 100 times below other atmospheric regions. We believe ice aerosols, the same aerosols implicated in the vertical velocity

  2. Modulation of Madden-Julian Oscillation on the polar mesospheric clouds

    NASA Astrophysics Data System (ADS)

    Li, T.; Yang, C.; Liu, X.; Yue, J.; Russell, J. M., III; Dou, X.

    2016-12-01

    The Madden-Julian Oscillation (MJO) is a dominant intra-seasonal variability in the equatorial troposphere, and is characterized by eastward propagation of tropical deep convection with a speed of 5 m/s from Indian ocean to central Pacific ocean, and with a intra-seasonal period of 30-90 days [Madden and Julian, 1994]. The MJO could significantly impact the global weather and climate [Zhang, 2005]. Recent studies also suggested that the Northern Hemisphere (NH) stratospheric polar vortex could be modulated by the MJO with strengthened (weakened) polar vortex during the enhanced (suppressed) convection in the tropical central Pacific Ocean [Garfinkel et al., 2014]. Using the Aura/Microwave Limb Sounder (MLS) and Aeronomy of Ice in the Mesosphere (AIM) observations, the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis interim dataset, and Specified Dynamics of Whole Atmosphere Community Climate Model (SD-WACCM) simulations, we study the influences of MJO in the mesosphere during the Northern winter and on the southern hemisphere summer polar mesospheric cloud (PMC). The anomalous PMC occurrence frequency is clearly correlated with anomalous water vapor and anti-correlated with anomalous temperature in the southern hemisphere polar mesosphere, suggesting that the MJO modulates the summer polar mesospheric temperature and water vapor and thus the formation of PMC. We will also discuss the possible mechanism of the mesosphere responses to MJO using SD-WACCM and ECMWF.

  3. Characterization of Polar Mesospheric Clouds Using Infrared Measurements From HALOE

    NASA Technical Reports Server (NTRS)

    Hervig, Mark E.

    2002-01-01

    Measurements from the Halogen Occultation Experiment (HALOE) revealed the infrared signature of polar mesospheric clouds (PMCs), for the first time, HALOE PMC observations at eight wavelengths (2.45 - 10 microns) show remarkable agreement with model PMC spectra based on ice particle extinction, and thus provide the first confirmation that water ice is the primary component of PMCs. Because PMCs respond to changes in temperature and water vapor, they are considered an indicator of global climate change. We propose to further the understanding of PMCs using a decade of infrared measurements form HALOE. This effort will characterize PMC spectral properties, extinction profiles, and size distributions. Using this information, HALOE measurements will be used to make simultaneous retrievals of H2O, O3, and temperature, in the presence of PMCs. The simultaneous retrievals of particle properties, H2O, O3, and temperature will be used with HALOE NO data to provide a significant step forward in the knowledge of PMC characteristics and formation conditions. We will challenge fundamental theories of PMC formation, and investigate changes in PMC properties and related conditions over the length of the HALOE measurement record. HALOE has been operating without flaw since it was launched on October 11, 1991. Consequently, ten southern and ten northern PMC seasons have been observed thus far, providing a wealth of data for the study of PMCs and related parameters.

  4. Characterization of Polar Mesospheric Clouds Using Infrared Measurements from HALOE

    NASA Technical Reports Server (NTRS)

    Hervig, Mark E.

    2002-01-01

    Measurements from the Halogen Occultation Experiment (HALOE) revealed the infrared signature of polar mesospheric clouds (PMCs), for the first time, HALOE PMC observations at eight wavelengths (2.45 - 10 microns) show remarkable agreement with model PMC spectra based on ice particle extinction, and thus provide the first confirmation that water ice is the primary component of PMCs. Because PMCs respond to changes in temperature and water vapor, they are considered an indicator of global climate change. We propose to further the understanding of PMCs using a decade of infrared measurements form HALOE. This effort will characterize PMC spectral properties, extinction profiles, and size distributions. Using this information, HALOE measurements will be used to make simultaneous retrievals of H2O3, and temperature, in the presence of PMCs. The simultaneous retrievals of particle properties, H2O3, and temperature will be used with HALOE NO data to provide a significant step forward in the knowledge of PMC characteristics and formation conditions. We will challenge fundamental theories of PMC formation, and investigate changes in PMC properties and related conditions over the length of the HALOE measurement record. HALOE has been operating without flaw since it was launched on October 11, 1991. Consequently, ten southern and ten northern PMC seasons have been observed thus far, providing a wealth of data for the study of PMC and related parameters.

  5. Range imaging results from polar mesosphere summer echoes

    NASA Astrophysics Data System (ADS)

    Zecha, Marius; Hoffmann, Peter; Rapp, Markus; Chen, Jenn-Shyong

    The range resolution of pulsed radars is usually limited by the transmitting pulse length and the sampling time. The so-called range imaging (RIM) has been developed to reduce these lim-itations. To apply this method the radar operates alternately over a set of distinct frequencies. Then the phase differences of the receiving signals can be used for optimization methods to generate high-resolution maps of reflections as function of range insight the pulse length. The technique has been implemented on the ALWIN VHF radar in Andenes (69) and the OSWIN VHF radar in Kühlungsborn (54N). Here we present results of the RIM method from measurements in polar mesosphere summer echoes -PMSE. These strong radar echoes are linked to ice particle clouds in the mesopause region. The dynamic of the PMSE can be reflected very well by RIM. The movement of PMSE and the edges of the extension can be tracked with a high altitude resolution. Comparisons between simultaneous measurements by RIM and by standard radar techniques demonstrate the advan-tages of RIM. Wave structures can be identified with RIM whereas they are not detectable with the lesser resolution of the standard measurements. Gravity wave parameter associated with these variations are estimated using the simultaneous measured velocity field.

  6. Retrieving mesospheric winds and gravity waves using high resolution radar measurements of polar mesospheric summer echoes with MAARSY

    NASA Astrophysics Data System (ADS)

    Stober, G.; Sommer, S.; Schult, C.; Chau, J. L.; Latteck, R.

    2013-12-01

    The Middle Atmosphere Alomar Radar System (MAARSY) located at the northern Norwegian island of Andøya (69.3 ° N, 16° E) observes polar mesosphere summer echoes (PMSE) on a regular basis. This backscatter turned out to be an ideal tracer of atmospheric dynamics and to investigate the wind field at the mesosphere/lower thermosphere (MLT) at high spatial and temporal scales. MAARSY is dedicated to explore the polar mesosphere at such high resolution and employs an active phased array antenna with the capability to steer the beam on a pulse-to-pulse basis, which permits to perform systematic scanning of PMSE and to investigate the horizontal structure of the backscatter. The radar also uses a 16 channel receiver system for interferometric applications e.g. mean angle of arrival analysis or coherent radar imaging. Here we present measurements using these features of MAARSY to study the wind field at the MLT applying sophisticated wind analysis algorithms such as velocity azimuth display or volume velocity processing to derive gravity wave parameters such as horizontal wave length, phase speed and propagation direction. Further, we compare the interferometrically corrected and uncorrected wind measurements to emphasize the importance to account for likely edge effects using PMSE as tracer of the dynamics. The observations indicate huge deviations from the nominal beam pointing direction at the upper and lower edges of the PMSE altering the wind analysis.

  7. Polar Mesospheric Cloud properties derived from the NASA Aeronomy of Ice in the Mesosphere Mission (2007-2008)

    NASA Astrophysics Data System (ADS)

    Thomas, Gary; Russell, J. M., III; Bailey, Scott

    The Aeronomy of Ice in the Mesosphere (AIM) is the first satellite experiment dedicated solely to the study of polar mesospheric clouds (PMC) and their atmospheric environment. Launched on April 25, 2007 into a 600-km circular sun-synchronous orbit, the three AIM instruments have performed flawlessly. The three instruments on board are (1) the Cloud Imaging and Particle Size (CIPS) experiment, (2) the Solar Occultation for Ice (SOFIE) experiment, and (3) the Cosmic Dust Experiment (CDE). CIPS consists of an array of four cameras, viewing downward and providing wide-field coverage of the polar regions in the UV at spatial resolutions of 5 km. SOFIE uses the technique of satellite solar occultation to measure vertical profiles of limb path atmospheric transmission within 16 spectral bands between wavelengths of 0.29 and 5.32 µm. The Cosmic Dust Experiment (CDE) on the AIM satellite is an impact detector designed to monitor the influx of micrometeorite particles greater than approximately 1 µm in radius. The overall goal of the two-year baseline mission is to determine why PMCs form and vary. AIM has provided the most detailed picture of NH clouds ever collected. The major results to date are: The clouds are highly-structured, are widespread and are variable on hourly to daily time scales. PMC brightness varies over horizontal scales of a few kilometers, and with the superior horizontal resolution of the images, highly-localized regions occur where the clouds are ten times brighter than measured by previous space-based instruments viewing the limb. As previously suspected, but never before seen, a population of very small ice particles was measured that is believed to be responsible for strong radar echoes from the summertime mesosphere. Mesospheric ice occurs in one continuous layer extending from below the main peak at 83 km up to around 90 km. Mesospheric cloud structures, resolved for the first time by the CIPS imager, exhibit complex features present in normal

  8. Studies of Polar Mesospheric Clouds from Observations by the Student Nitric Oxide Explorer

    NASA Technical Reports Server (NTRS)

    Bailey, Scott M.

    2005-01-01

    The Geospace Sciences SR&T award NAG5-12648 "Studies of polar mesospheric clouds from observations by the Student Nitric Oxide Explorer" has been completed. The project was very successful in completing the proposed objectives and brought forth unexpected results in the study of Polar Mesospheric Clouds (PMCs). This work has provided key results to the community, provided valuable experience to two students, and inspired new research and collaborations with other research groups. Here we briefly summarize the progress and the scientific results.

  9. Temperature Trends in the Polar Mesosphere between 2002-2007 using TIMED/SABER Data

    NASA Technical Reports Server (NTRS)

    Goldberg, Richard A.; Kutepov, Alexander A.; Pesnell, William Dean; Latteck, Ralph; Russell, James M.

    2008-01-01

    The TIMED Satellite was launched on December 7, 2001 to study the dynamics and energy of the mesosphere and lower thermosphere. The TIMED/SABER instrument is a limb scanning infrared radiometer designed to measure a large number of minor constituents as well as the temperature of the region. In this study, we have concentrated on the polar mesosphere, to investigate the temperature characteristics as a function of spatial and temporal considerations. We used the recently revised SABER dataset (1.07) that contains improved temperature retrievals in the Earth polar summer regions. Weekly averages are used to make comparisons between the winter and summer, as well as to study the variability in different quadrants of each hemisphere. For each year studied, the duration of polar summer based on temperature measurements compares favorably with the PMSE (Polar Mesospheric Summer Echoes) season measured by radar at the ALOMAR Observatory in Norway (69 N). The PMSE period should also define the summer period suitable for the occurrence of polar mesospheric clouds. The unusual short and relatively warm polar summer in the northern hemisphere

  10. Temperature Trends in the Polar Mesosphere between 2002-2007 using TIMED/SABER Data

    NASA Technical Reports Server (NTRS)

    Goldberg, Richard A.; Kutepov, Alexander A.; Pesnell, William Dean; Latteck, Ralph; Russell, James M.

    2008-01-01

    The TIMED Satellite was launched on December 7, 2001 to study the dynamics and energy of the mesosphere and lower thermosphere. The TIMED/SABER instrument is a limb scanning infrared radiometer designed to measure a large number of minor constituents as well as the temperature of the region. In this study, we have concentrated on the polar mesosphere, to investigate the temperature characteristics as a function of spatial and temporal considerations. We used the recently revised SABER dataset (1.07) that contains improved temperature retrievals in the Earth polar summer regions. Weekly averages are used to make comparisons between the winter and summer, as well as to study the variability in different quadrants of each hemisphere. For each year studied, the duration of polar summer based on temperature measurements compares favorably with the PMSE (Polar Mesospheric Summer Echoes) season measured by radar at the ALOMAR Observatory in Norway (69 N). The PMSE period should also define the summer period suitable for the occurrence of polar mesospheric clouds. The unusual short and relatively warm polar summer in the northern hemisphere

  11. The DROPPS Program: A Rocket/Lidar/Radar Study of the Polar Summer Mesosphere

    NASA Technical Reports Server (NTRS)

    Goldberg, Richard A.; Holzworth, R. H.; Schmidlin, F. J.; Voss, H. D.; Tuzzolino, A. J.; Croskey, C. L.; Mitchell, J. D.; vonZhan, U.; Singer, W.

    1999-01-01

    During July of 1999, two sequences of rockets were launched from the Norwegian rocket range in Andoya, Norway. The purpose of these studies was to investigate the properties of the polar summer mesosphere, particularly relating to polar mesospheric summer echoes (PMSE) and their possible relationship to noctilucent clouds (NLC). Each of two sequences was anchored with a DROPPS Black Brant payload, consisting of 20 instruments to measure the electrodynamic and optical structure of the mesosphere and lower thermosphere. These were provided by participants from five American and two European scientific laboratories. The DROPPS (Distribution and Role of Particles in the Polar Summer) payloads were each accompanied by a sequence of meteorological rockets, and by several European payloads designed to study electrodynamics structure of the same region. ALOMAR (Arctic Lidar Observatory for Middle Atmosphere Research) Lidars, and MF (Medium Frequency) and MST (Mesosphere, Stratosphere, and Troposphere) Radars were used to continuously monitor the mesosphere for NLCs and PMSEs respectively. EISCAT VHF (European Incoherent Scatter Radar Very High Frequency) radar provided similar information about PMSEs downstream from the launch site. Sequence 1 was launched on the night of 5-6 July into a strong PMSE display coupled with a weak NLC at the low end of the PMSE. Sequence 2 was launched on the early morning of 14 July into a strong NLC with no PMSE evident. Here we describe the details of the program along with preliminary results.

  12. The DROPPS Program: A Rocket/Lidar/Radar Study of the Polar Summer Mesosphere

    NASA Technical Reports Server (NTRS)

    Goldberg, Richard A.; Holzworth, R. H.; Schmidlin, F. J.; Voss, H. D.; Tuzzolino, A. J.; Croskey, C. L.; Mitchell, J. D.; vonZhan, U.; Singer, W.

    1999-01-01

    During July of 1999, two sequences of rockets were launched from the Norwegian rocket range in Andoya, Norway. The purpose of these studies was to investigate the properties of the polar summer mesosphere, particularly relating to polar mesospheric summer echoes (PMSE) and their possible relationship to noctilucent clouds (NLC). Each of two sequences was anchored with a DROPPS Black Brant payload, consisting of 20 instruments to measure the electrodynamic and optical structure of the mesosphere and lower thermosphere. These were provided by participants from five American and two European scientific laboratories. The DROPPS (Distribution and Role of Particles in the Polar Summer) payloads were each accompanied by a sequence of meteorological rockets, and by several European payloads designed to study electrodynamics structure of the same region. ALOMAR (Arctic Lidar Observatory for Middle Atmosphere Research) Lidars, and MF (Medium Frequency) and MST (Mesosphere, Stratosphere, and Troposphere) Radars were used to continuously monitor the mesosphere for NLCs and PMSEs respectively. EISCAT VHF (European Incoherent Scatter Radar Very High Frequency) radar provided similar information about PMSEs downstream from the launch site. Sequence 1 was launched on the night of 5-6 July into a strong PMSE display coupled with a weak NLC at the low end of the PMSE. Sequence 2 was launched on the early morning of 14 July into a strong NLC with no PMSE evident. Here we describe the details of the program along with preliminary results.

  13. Characterizing Polar Mesospheric Summer Echo Edge Effect Formation

    NASA Astrophysics Data System (ADS)

    Yee, J.; Bahcivan, H.

    2013-12-01

    Polar Mesospheric Summer Echoes (PMSEs) form in the summer mesopause region, between altitudes of 80 and 90 km. This phenomenon occurs in this region because of the extremely cold temperatures that allow for ice particles to develop, sediment, and grow to sizes as large as ~20 nm. Because these ice particles are immersed in the plasma of the D-region, electrons can attach to the ice surfaces and charge them. There are two trains of thought when it comes to the backscatter seen in sounding rocket and radar measurements of PMSEs. The first assumes that the structure of the PMSEs is driven by turbulent velocity fields and that radar detections are due to turbulent scattering. The second theory on the scatter from PMSE structures is that the echoes result from multiple sharp small-scale ledges that produce an edge scatter. In decomposing sounding rocket data, results have indicated that both scattering mechanisms play a role in PMSE backscatter. However, whereas the turbulent scatter theory is well developed, the physics behind the sharp-edge phenomena in the edge scattering theory has not been explained to date. We investigate the formation of the sharp edges in electron density detected by sounding rockets and in backscattered power detected by ground-based radars during PMSE regions by exploring the initial process by which PMSEs form using a one dimensional (1D) particle-in-cell (PIC) simulation. The simulation, adapted from the Plasma Theory and Simulation Group at UC Berkley, starts with the ice particles immersed in a warm electron-ion plasma and allows for the charging process of the ice particles. Starting with an initial Gaussian distribution of ice particles, we show that as the ice particles charge, they increase in mass more quickly (i.e. accumulate more electrons and ions) at the edges of the PMSE structure. This increased mass decreases the diffusion rates of the edges and 'freezes' the edges of the PMSE. This result demonstrates that the reason for the

  14. An overview of NLC-91: A rocket/radar study of the polar summer mesosphere

    NASA Technical Reports Server (NTRS)

    Goldberg, R. A.; Kopp, E.; Witt, G.; Swartz, W. E.

    1993-01-01

    In late July and early August of 1991, a major suborbital scientific campaign (NLC-91) involving scientists from eight countries was conducted as ESRANGE, Kiruna, Sweden and at Heiss Island, Russia. The purpose of the program was to investigate the chemical, dynamical, and electrodynamical properties of the polar summer mesosphere. Thirty one rocket flights were coordinated with two coherent radar facilities, EISCAT and CUPRI, and with other ground-based observatories and facilities. This permitted direct comparison between the in situ measurements and those obtained by remote sensing of the mesosphere via continuous ground-based monitoring. The primary objectives of the campaign were to study noctilucent clouds (NLCs) and polar mesospheric summer echoes (PMSEs), including their possible relationship to local aerosols and/or small scale turbulence. This overview describes the scientific program, discusses the geophysical conditions during launch activities, and reviews some of the preliminary results. More detailed results can be found in the papers which follow.

  15. Long term observations of polar mesospheric echoes at Andøya

    NASA Astrophysics Data System (ADS)

    Latteck, Ralph; Strelnikova, Irina; Renkwitz, Toralf; Sommer, Svenja

    2016-04-01

    Polar mesosphere summer echoes (PMSE) are strong enhancements of received signal power at very high radar frequencies occurring at altitudes between about 80 and 95 km at polar latitudes during summer. These echoes are caused by inhomogeneities in the electron density of the radar Bragg scale within the plasma of the cold summer mesopause region in the presence of negatively charged ice particles. Thus the occurrence of PMSE contains information about mesospheric temperature and water vapour content but also depends on the ionisation due to solar electromagnetic radiation and precipitating high energetic particles. Continuous observations of PMSE have been done on the North-Norwegian island Andøya (69.3°N, 16.0°E) since 1994 using different VHF radars. The PMSE occurrence rate is positively correlated with the geomagnetic Ap index, however not correlated with the solar Lyman α radiation and shows a significant positive trend during the time interval from 1994 until 2012. VHF radar echoes have been observed also during winter times but in the mid mesosphere from about 55 to 85 km altitude. These so called polar mesosphere winter echoes (PMWE) have been observed continuously at Andøya since 2004 using the ALWIN VHF radar (until 2008) and the Middle Atmosphere Alomar Radar System MAARSY (since 2011). Using the more sensitive MAARSY compared to the previous VHF radar systems operated at the site, results in more detections characterized by smaller volume reflectivity values down to 4 ṡ 10-18m-1. The end of the winter season is now hard to determine since mesospheric echoes have also been observed below altitudes of 80 km during non winter months, particularly around the end of May, i.e. the beginning of the polar mesospheric summer echo season. These observations indicate that the physical mechanism for creating the lower mesospheric echoes is present during the early summer months as well. We present results from long term observations of polar mesospheric

  16. Long-term changes of mesospheric summer echoes at polar and middle latitudes

    NASA Astrophysics Data System (ADS)

    Bremer, J.; Hoffmann, P.; Höffner, J.; Latteck, R.; Singer, W.; Zecha, M.; Zeller, O.

    2006-12-01

    Strong mesospheric VHF radar echoes can be observed during summer months mainly at polar latitudes (polar mesosphere summer echoes, PMSE) but with a reduced echo power also at middle latitudes (mesosphere summer echoes, MSE). This phenomenon of unexpected strong radar echoes is closely connected with the existence of small ice particles in the upper mesosphere and mesopause region. Therefore, these echoes contain information about the mesospheric temperature and water vapour content. But the strength of (P)MSE also depends on the level of ionisation due to incident solar wave radiation and precipitating high energetic particle fluxes. Using observations with VHF radars at Andenes (69.3°N, 16.0°E) since 1994 and at Kühlungsborn (54.6°N, 11.8°E) since 1998, the dependence of the strength of the (P)MSE on the solar and geomagnetic activity has been analysed and, in addition, possible long-term variations were derived. The special behaviour of the year 2002 is discussed in connection with an interhemispheric coupling due to enhanced planetary wave activity at the southern hemisphere winter season. There are some hints of small trends with increasing radar echo power and duration of the (P)MSE season in qualitative agreement with some changes of the observed occurrences rate of noctilucent clouds (NLC) and of the brightness of polar mesospheric clouds (PMC). However, the significance levels of the derived trends are low, and in most cases the trends are not significantly different from zero.

  17. Contribution to polar albedo from a mesospheric aerosol layer

    NASA Technical Reports Server (NTRS)

    Hummel, J. R.

    1977-01-01

    An examination is made of the impact of a layer of particulate matter, assumed to be ice crystals, on the albedo of the polar region. The model is time dependent, includes the growth of the layer, and incorporates the diffuse nature of radiation reflected from the surface and atmosphere. Although the magnitude of the effect is about an order of magnitude less than previous results, the impact is one of heating instead of cooling. It is also shown that ignoring the diffuse nature of the radiation reflected from the underlying earth-atmosphere system, as has been done in many previous simple models, can result in overestimation of the climatological impact of aerosols in sign and magnitude by a factor of up to 4-6.

  18. Inter-hemispheric asymmetry in polar mesosphere summer echoes and temperature at 69° latitude

    NASA Astrophysics Data System (ADS)

    Morris, Ray J.; Klekociuk, Andrew R.; Latteck, Ralph; Singer, Werner; Holdsworth, David A.; Murphy, Damian J.

    2009-03-01

    An inter-hemispheric asymmetry is found in the characteristics of polar mesosphere summer echoes (PMSE) and upper mesosphere temperatures at conjugate latitudes (~69°) above Antarctica and the Arctic. The second complete mesosphere-stratosphere-troposphere (MST) radar summer observation season at Davis (68.6°S) revealed that PMSE occur less frequently, with lower strength and on average 1 km higher compared with their northern counterparts at Andenes (69.3°N). We consider the thermodynamic state of the mesosphere for conjoining hemispheric summers based on satellite and ground-based radar measurements, and show the mesopause region near ~80-87 km of the Southern Hemisphere (SH) to be up to 7.5 K warmer than its Northern Hemisphere (NH) counterpart. We show that this is consistent with our observation of asymmetries in the characteristics of PMSE and demonstrate how the mesosphere meridional wind field influences the existence and strength of the echoes in both hemispheres.

  19. The Mesospheric OH* layer above Spitsbergen: Investigation of polar mesospheric dynamics and temperature trends by means of ground based OH* airglow measurements and model studies

    NASA Astrophysics Data System (ADS)

    Kowalewski, S.; Palm, M.; Notholt, J.

    2012-04-01

    The hydroxyl (OH*) emission layer is one of the dominant features of the mesopause region. It is primarily formed via the reaction of ozone and atomic hydrogen, which results in vibrationally excited OH* radicals. Due to radiative deexcitation, these radicals contribute to the airglow, which we can observe at different emission bands. For low excitation levels (ν≤6) of OH*, its lifetime can be sufficient to become thermalized by collision with the surrounding molecules, hence its emission can serve as a measure of ambient temperature. Because of the remoteness of the mesosphere, this offers a valuable source of information on mesospheric temperatures. While satellite based observations of the OH* layer offer comprehensive data sets on global scales, the spatial as well as the temporal resolution is limited by the corresponding orbits. Ground based measurements can fill this gap and enable us to study mesospheric disturbances at shorter time scales. Particularly the polar mesospheric region can be subject to large variability, which becomes apparent in the brightness and temperature signals from the OH* emission layer. In this poster we present temperatures derived from measurements taken from a Fourier Transform Spectrometer (FTS), which is located at the AWIPEV Arctic Research Base in Ny-Ålesund, Spitsbergen (79°). Measurements are available since 2007 and cover various emission bands of OH* in the spectral region from 5900 cm^-1 to 6500 cm^-1. We illustrate large scale polar mesospheric warming events, which have a striking impact on mesospheric dynamics and the coupling to the lower atmosphere. In addition to satellite based observations that we compare with our data, we illustrate the ability of our instrument to resolve short term perturbations. We discuss how we will combine these observations to model studies, in order to shed more light on the associated polar mesospheric dynamics in an upcoming analyis.

  20. How Temperature and Water levels affect Polar Mesospheric Cloud Formation

    NASA Astrophysics Data System (ADS)

    Smith, L. L.; Randall, C. E.; Harvey, V.

    2012-12-01

    Using the Cloud Imaging and Particle Size (CIPS) instrument data, which is part of the Aeronomy in the Mesosphere (AIM) mission, we compare the albedo and ice water content measurements of CIPS with the Navy Operation Global Atmospheric Prediction System - Advanced Level Phyiscs and High Altitude (NOGAPS-ALPHA) temperature and water vapor data in order to derive a greater understanding of cloud formation and physics. We particularly focus on data from June 2007 and July 2007 in this case study because of particular cloud structures and formations during this time period for future studies.

  1. Horizontally resolved structures of polar mesospheric echoes obtained with the Middle Atmosphere Alomar Radar System

    NASA Astrophysics Data System (ADS)

    Latteck, Ralph; Zecha, Marius; Rapp, Markus; Stober, Gunter; Singer, Werner

    2012-07-01

    Polar Mesosphere Summer Echoes have been observed in Andenes/Norway (69°N, 16°E) for more than 18 years using the Alomar SOUSY and the ALWIN VHF radars. In 2011 the Leibniz-Institute of Atmospheric Physics in Kühlungsborn completed the installation of the Middle Atmosphere Alomar Radar System ({MAARSY}). The new radar is designed for atmospheric studies from the troposphere up to the lower thermosphere, especially for the investigation of horizontal structures of polar mesospheric echoes. The system is composed of an active phased antenna consisting of 433 array elements and an identical number of transceiver modules individually controllable in frequency, phase, and output power on a pulse-to-pulse basis. This arrangement allows very high flexibility of beam forming and beam steering with a symmetric 3.6° small radar beam and arbitrary beam pointing directions down to 30° off-zenith. The monitoring of polar mesosphere echoes using a vertical pointed radar beam has been continued already during the construction period of MAARSY in order to complete the long term data base available for Andenes. Additionally first multi-beam scanning experiments using up to 97 beams quasi-simultaneously in the mesosphere have been carried out during several campaigns starting in summer 2010. Sophisticated wind analysis methods such as an extended velocity azimuth display have been applied to retrieve additional parameters from the wind field, e.g. horizontal divergence, vertical velocity, stretching and shearing deformation. The results provide a first insight into the strong horizontal variability of scattering structures occurring in the polar mesosphere over Andenes during summer and winter time. The implementation of interferometric radar imaging methods offers further improvement of the horizontal and the vertical resolution.

  2. Statistical Characteristics of Polar Mesospheric Gravity Waves Observed Over Alaska

    NASA Astrophysics Data System (ADS)

    Negale, M.; Nielsen, K.; Taylor, M. J.; Pautet, P.; Dyrland, M. E.; Suzuki, S.

    2013-12-01

    Short-period (<1 hr) gravity wave observations over the Arctic region are few and their impact on the Arctic mesosphere lower thermosphere (MLT) region via momentum deposition is of high interest, but has yet to be determined. The Mesospheric Airglow Imaging and Dynamics (MAID) project was initiated in January 2011 to investigate the presence and dynamics of these waves over the interior of Alaska. Observations were made from the Davis Building at Poker Flat Research Range (PFRR) (65N) using an all-sky imager. This site provides an exceptional opportunity to establish a long-term climatology of short-period gravity waves in the Arctic. Here, we present summary measurements of prominent gravity waves focusing on their winter-time spatial and temporal characteristics. Measurements were made over two consecutive winters in 2011 and 2012 yielding 117 quasi-monochromatic wave events obtained from sequential OH (715-930 nm) images. Their characteristics are compared with recent gravity wave observations at Resolute Bay, Canada (75N), ALOMAR Station, Norway (69N), Svalbard (78N) in the Arctic, and with Rothera Station (76S) in Antarctic. The distributions of the wave parameters measured at PFRR were found to be similar to those of the other high-latitude sites, except for the direction of propagation. The wave headings observed at PFRR exhibited dominant preference for motion towards the east, while the other high-latitude observations reported westward motion. To investigate the preferred wave directionality, we look at the effects of critical level filtering using zonal and meridional winds obtained from NASA's Modern-Era Retrospective Analysis for Research and Applications (MERRA) and the Horizontal Wind Model 2007 (HWM07).

  3. Generation of waves by jet-stream instabilities in winter polar stratosphere/mesosphere

    NASA Astrophysics Data System (ADS)

    Shpynev, B. G.; Churilov, S. M.; Chernigovskaya, M. A.

    2015-12-01

    In the paper we investigate the manifestation of large-scale and middle-scale atmospheric irregularities observed on stratosphere/mesosphere heights. We consider typical patterns of circulation in stratosphere and lower mesosphere which are formed due to a difference of air potential energy between equatorial and polar latitudes, especially in polar night conditions. On the base of ECMWF Era Interim reanalysis data we consider the dynamics of midlatitude winter jet-streams which transfer heat from low latitudes to polar region and which develop due to equator/pole baroclinic instabilities. We consider typical patterns of general circulation in stratosphere/lower mesosphere and reasons for creation of flaky structure of polar stratosphere. Also we analyze conditions that are favorable for splitting of winter circumpolar vortex during sudden stratosphere warming events and role of phase difference tides in this process. The analysis of vertical structure of the stratosphere wind shows the presence of regions with significant shear of horizontal velocity which favors for inducing of shear-layer instability that appears as gravity wave on boundary surface. During powerful sudden stratosphere warming events the main jet-stream can amplify these gravity waves to very high amplitudes that causes wave overturning and releasing of wave energy into the heat due to the cascade breakdown and turbulence. For the dynamics observed in reanalysis data we consider physical mechanisms responsible for observed phenomena.

  4. Evidence for Interhemispheric Coupling during the Unusual Northern Polar Summer Mesosphere of 2002

    NASA Technical Reports Server (NTRS)

    Goldberg, Richard A.; Feofilov, Artem; Kutepov, Alexandr; Schmidlin, Francis J.; Russell, James M.

    2009-01-01

    Data from the MaCWAVE MIDAS Rocket Program launched during July, 2002, from Andoya Rocket Range (ARR) in Norway have demonstrated that the temperature structure of the summer polar mesosphere during this period was atypical, at least above ARR. The summer polar mesopause region was warmer than normal and of shorter duration than for other years analyzed. Theoretical studies have since been published that imply that the abnormal characteristics of this polar summer were generated by unusual dynamical processes occurring in the southern polar winter hemisphere. We have used data from the SABER instrument aboard the NASA TIMED Satellite to study these characteristics on a global scale and compare them with the features observed in the ensuing seven years. For background, The TIMED Satellite was launched on December 7, 2001 to study the dynamics and energy of the mesosphere and lower thermosphere (MLT). The SABER instrument on TIMED is a limb scanning infrared radiometer designed to measure a large number of minor constituents as well as temperature of the MLT. In this study, we have investigated the temperature characteristics of the polar mesosphere as a function of spatial and temporal considerations. We have used the most recent SABER dataset (1.07) that includes the improved temperature retrievals in Earth polar regions, Weekly averages were used 10 make the comparisons between the winter and summer hemispheres. The unusually short polar summer in the northern hemisphere during 2002 is clearly defined by this analysis and is shown to be unique for the 7 years analyzed. Furthermore, the data analysis agrees with recent theoretical studies showing that this behavior is a result of anomalous heating events in the southern polar stratosphere. The time sequence of the coupling process, as predicted by recent theoretical models, is well defined in a sequence of weekly temperature contour maps measured by SABER.

  5. Evidence for Interhemispheric Coupling during the Unusual Northern Polar Summer Mesosphere of 2002

    NASA Technical Reports Server (NTRS)

    Goldberg, Richard A.; Feofilov, Artem; Kutepov, Alexandr; Schmidlin, Francis J.; Russell, James M.

    2009-01-01

    Data from the MaCWAVE MIDAS Rocket Program launched during July, 2002, from Andoya Rocket Range (ARR) in Norway have demonstrated that the temperature structure of the summer polar mesosphere during this period was atypical, at least above ARR. The summer polar mesopause region was warmer than normal and of shorter duration than for other years analyzed. Theoretical studies have since been published that imply that the abnormal characteristics of this polar summer were generated by unusual dynamical processes occurring in the southern polar winter hemisphere. We have used data from the SABER instrument aboard the NASA TIMED Satellite to study these characteristics on a global scale and compare them with the features observed in the ensuing seven years. For background, The TIMED Satellite was launched on December 7, 2001 to study the dynamics and energy of the mesosphere and lower thermosphere (MLT). The SABER instrument on TIMED is a limb scanning infrared radiometer designed to measure a large number of minor constituents as well as temperature of the MLT. In this study, we have investigated the temperature characteristics of the polar mesosphere as a function of spatial and temporal considerations. We have used the most recent SABER dataset (1.07) that includes the improved temperature retrievals in Earth polar regions, Weekly averages were used 10 make the comparisons between the winter and summer hemispheres. The unusually short polar summer in the northern hemisphere during 2002 is clearly defined by this analysis and is shown to be unique for the 7 years analyzed. Furthermore, the data analysis agrees with recent theoretical studies showing that this behavior is a result of anomalous heating events in the southern polar stratosphere. The time sequence of the coupling process, as predicted by recent theoretical models, is well defined in a sequence of weekly temperature contour maps measured by SABER.

  6. Long-term changes of mesospheric summer echoes at polar and middle latitudes

    NASA Astrophysics Data System (ADS)

    Bremer, J.; Hoffmann, P.; Latteck, R.; Singer, W.; Zecha, M.

    During summer season unexpectedly strong radar echoes from an altitude range between about 80-90 km can regularly be observed at polar latitudes (polar mesosphere echoes, PMSE), but with markedly reduced amplitudes also at middle latitudes (mesosphere summer echoes, MSE). These (P)MSE are strongly coupled with the existence of small ice particles and are therefore dependent on mesospheric temperature and water vapour content. On the other side the strength of the (P)MSE depends also on the level of ionization in the mesopause region. Using VHF radar observations at Andenes (69.3N, 16.0E) between 1994 and 2003 as well as at Kühlungsborn (54.6N, 11.8E) between 1998 and 2003 a clear influence of solar and geomagnetic activity upon (P)MSE has been found. The reasons of the detected correlations are discussed for polar and middle latitudes. After elimination of the solar and geomagnetically induced parts by a twofold regression analysis long-term trends of (P)MSE are estimated. There are indication of slightly positive trends of PMSE as well as MSE occurrence rates. Due to the relatively short data series available the derived trends are however not statistically significant. Nevertheless some qualitative agreement has been found with long-term variations of the occurrence rate and brightness of noctilucent clouds (NLC).

  7. VHF radar measurements in the summer polar mesosphere

    NASA Technical Reports Server (NTRS)

    Ruester, R.; Reid, I. M.; Czechowsky, P.; Schmidt, G.

    1989-01-01

    Measurements in the mesosphere over Andoya/Norway (69 N, 16 E) were carried out using the mobile SOUSY-VHF radar with an extended beam configuration during the MAC/SINE campaign in summer 1987. First results of a 48 h and a 3 h observational period for heights between about 83 and 91 km are presented. Zonal mean winds are characterized by a strong westward flow of up to 50/ms, whereas the equatorward directed meridional component is weaker. The dominating semidiurnal tide has amplitudes up to 30/ms and a vertical wavelength of about 55 km. The diurnal tide is less pronounced. The total upward flux of horizontal momentum takes values of -2 sq m/sq s near 84 km and increases with increasing height, reaching a maximum value of 22 sq m/sqs for both the zonal and meridional components. However, measurements of the horizontal isotropy of the wave field suggest significant anisotropy. The major contribution to the momentum flux is from the 10 min to 1 h period range below about 87 km, and from the 1 to 6 h period range above this height.

  8. Study of the mesosphere using wide-field twilight polarization measurements: Early results beyond the polar circle

    NASA Astrophysics Data System (ADS)

    Ugolnikov, O. S.; Kozelov, B. V.

    2016-07-01

    This paper discusses the results of early measurements of temperature and dust in the mesosphere on the basis of wide-field twilight sky polarimetry, which began in 2015 in Apatity (North of Russia, 67.6° N, 33.4° E) using the original entire-sky camera. These measurements have been performed for the first time beyond the Polar Circle in the winter and early spring period. The general polarization properties of the twilight sky and the procedure for identifying single scattering are described. The key results of the study include the Boltzmann temperature values at altitudes higher than 70 km and the conclusion on a weak effect of dust on scattering properties of the mesosphere during this period.

  9. Radar Observations of Polar Mesospheric Clouds Over Alaska during Summer 2001

    NASA Astrophysics Data System (ADS)

    Kelley, M. C.; Chen, C. Y.; Ramos, C.

    2001-12-01

    Radar observations of the Arctic mesopause region were conducted in Alaska during the summer of 2001 at the High Power Auroral Stimulation (HIPAS) Observatory and at the High Frequency Active Auroral Research Program (HAARP) Facility. HIPAS, operating at 4.53 MHz, probed the mesosphere above Fairbanks from 80 to 90 km with 2 km height resolution and was sensitive to polar mesospheric summer echoes (PMSE). PMSE were seen for at least 50 % of the observation period. Two campaigns were carried out at HAARP, { ~} 300 km south of HIPAS, near Gakona, Alaska. The purpose of the experiments was to create a seasonal database of these phenomena. We describe the scientific program, discuss the geophysical conditions during the observations, and present some of the preliminary results.

  10. On the occurrence and formation of multiple layers of polar mesosphere summer echoes

    NASA Astrophysics Data System (ADS)

    Hoffmann, P.; Rapp, M.; Serafimovich, A.; Latteck, R.

    2005-03-01

    Polar Mesosphere Summer Echoes (PMSE) have been studied at Andenes (69°N, 16°E), Norway, using VHF radar observations from 1994-1997 and since 1999. One remarkable feature of all PMSE is the fact that the radar echoes often occur in the form of two or more distinct layers that can persist for periods of up to several hours. Until now, the layering mechanism leading to these multiple structures is not well understood. Here we are studying the occurrence and the mean altitude distribution of these multiple layer events. To discuss the processes that are potentially responsible for the creation of these multiple structures, we apply a microphysical model of the generation and growth of mesospheric ice particles under the influence of temperature and wind variations caused by a long period gravity wave. Finally, this model approach is tested with gravity wave characteristics derived from MF and VHF radar wind measurements during the PMSE observations.

  11. Long-term changes of polar mesosphere summer echoes at 69°N

    NASA Astrophysics Data System (ADS)

    Latteck, R.; Bremer, J.

    2013-09-01

    Polar mesosphere summer echoes (PMSE) are strong enhancements of received signal power at very high radar frequencies occurring at altitudes between about 80 and 95km at polar latitudes during summer. PMSE are caused by inhomogeneities in the electron density of the radar Bragg scale within the plasma of the cold summer mesopause region in the presence of negatively charged ice particles. Thus, the occurrence of PMSE contains information about mesospheric temperature and water vapor content but also depends on the ionization due to solar electromagnetic radiation and precipitating high energetic particles. Continuous and homogeneous observations of PMSE have been done on the North-Norwegian Island Andøya (69.3°N, 16.0°E) from 1994 until 2008 using the ALOMAR SOUSY and the ALWIN radar at 53.5MHz. In 2009, the Leibniz-Institute of Atmospheric Physics in Kühlungsborn, Germany started the installation of the Middle Atmosphere ALOMAR Radar System (MAARSY) at the same location. The observation of mesospheric echoes could be continued in spring 2010 starting with an initial stage of expansion of MAARSY and is carried out with the completed installation of the radar since May 2011. Since both the ALWIN radar and MAARSY are calibrated, the received echo strength of PMSE from 14 years of mesospheric observations (1999-2012) could be converted into absolute signal power. This data series could be extended to the years 1994 until 1997 on the basis of signal-to-noise ratio values derived during the years between 1994 and 2008. The PMSE occurrence rate is positively correlated with the geomagnetic Ap index (significance level χ=85-95%), however, is not correlated with the solar Lyman α radiation. Using different regression analysis methods, the PMSE occurrence rates show a significant positive trend during the time interval from 1994 until 2012 (χ=95-99%).

  12. Gravity Waves in the Polar Stratosphere and Mesosphere and Their Relations with Ice Cloud Observed Sofie/AIM

    NASA Astrophysics Data System (ADS)

    Liu, X.; Yue, J.; Xu, J.; Wang, L.; Yuan, W.; Russell, J. M., III; Hervig, M. E.

    2014-12-01

    A six-years (2007-2013) temperature dataset from the Solar Occultation for Ice Experiment (SOFIE) onboard the Aeronomy of Ice in the Mesosphere (AIM) satellite is used to extract gravity waves (GWs) in the polar stratosphere and mesosphere of both hemispheres. These data are continuous in the polar regions. The monthly mean GW potential energy (PE) increases exponentially with a scale height of ~13 km in the upper stratosphere and mesosphere. GWs are stronger in the winter than in the summer and exhibit strong annual variation. GWs are stronger in the southern polar region (SPR) than in the northern polar region (NPR) except in the summer months. This is likely because there are stronger and longer-lasting zonal wind jets in the SPR stratosphere, as revealed from Modern-Era Retrospective analysis for Research and Applications (MERRA) wind data. The longitudinal variations of PE in the winter polar stratosphere are consistent with the elevated regions. In the mesosphere, the longitudinal variations of PE do not vary with height significantly. The correlations between GW PE and the column ice water content (IWC, an indicator of the polar mesosphere cloud) exhibit longitudinal and annual variations.

  13. The MaCWAVE program to study gravity wave influences on the polar mesosphere

    NASA Astrophysics Data System (ADS)

    Goldberg, R. A.; Fritts, D. C.; Schmidlin, F. J.; Williams, B. P.; Croskey, C. L.; Mitchell, J. D.; Friedrich, M.; Russell, J. M., III; Blum, U.; Fricke, K. H.

    2006-07-01

    MaCWAVE (Mountain and Convective Waves Ascending VErtically) was a highly coordinated rocket, ground-based, and satellite program designed to address gravity wave forcing of the mesosphere and lower thermosphere (MLT). The MaCWAVE program was conducted at the Norwegian Andøya Rocket Range (ARR, 69.3° N) in July 2002, and continued at the Swedish Rocket Range (Esrange, 67.9° N) during January 2003. Correlative instrumentation included the ALOMAR MF and MST radars and RMR and Na lidars, Esrange MST and meteor radars and RMR lidar, radiosondes, and TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics) satellite measurements of thermal structures. The data have been used to define both the mean fields and the wave field structures and turbulence generation leading to forcing of the large-scale flow. In summer, launch sequences coupled with ground-based measurements at ARR addressed the forcing of the summer mesopause environment by anticipated convective and shear generated gravity waves. These motions were measured with two 12-h rocket sequences, each involving one Terrier-Orion payload accompanied by a mix of MET rockets, all at ARR in Norway. The MET rockets were used to define the temperature and wind structure of the stratosphere and mesosphere. The Terrier-Orions were designed to measure small-scale plasma fluctuations and turbulence that might be induced by wave breaking in the mesosphere. For the summer series, three European MIDAS (Middle Atmosphere Dynamics and Structure) rockets were also launched from ARR in coordination with the MaCWAVE payloads. These were designed to measure plasma and neutral turbulence within the MLT. The summer program exhibited a number of indications of significant departures of the mean wind and temperature structures from ``normal" polar summer conditions, including an unusually warm mesopause and a slowing of the formation of polar mesospheric summer echoes (PMSE) and noctilucent clouds (NLC). This was suggested

  14. First Measurements of Polar Mesospheric Summer Echoes by a Tri-static Radar System

    NASA Astrophysics Data System (ADS)

    La Hoz, C.

    2015-12-01

    Polar Mesospheric Summer Echoes (PMSE) have been observed for the first time by a tri-static radar system comprising the EISCAT VHF (224 MHz, 0.67 m Bragg wavelength) active radar in Tromso (Norway) and passive receiving stations in Kiruna, (Sweden) and Sodankyla (Finland). The antennas at the receiving stations, originally part of the EISCAT tri-static UHF radar system at 930 MHz, have been refitted with new feeder systems at the VHF frequency of the transmitter in Tromso. The refitted radar system opens new opportunities to study PMSE for its own sake and as a tracer of the dynamics of the polar mesosphere, a region that is difficult to investigate by other means. The measurements show that very frequently both remote receiving antennas detect coherent signals that are much greater than the regular incoherent scattering due to thermal electrons and coinciding in time and space with PMSE measured by the transmitter station in Tromso. This represents further evidence that PMSE is not aspect sensitive, as was already indicated by a less sensitive radar system in a bi-static configuration, and implying that the underlying atmospheric turbulence, at least at sub-meter scales, is isotropic in agreement with Kolmogorov's hypothesis. Measurements also show that the vertical rate of fall of persistent features of PMSE is the same as the vertical line of sight velocity inferred from the doppler shift of the PMSE signals. This equivalence forms the basis for using PMSE as a tracer of the dynamics of the background mesosphere. Thus, it is possible to measure the 3-dimensional velocity field in the PMSE layer over the intersection volume of the three antennas. Since the signals have large signal-to-noise ratios (up to 30 dB), the inferred velocities have high accuracies and good time resolutions. This affords the possibility to make estimates of momentum flux in the mesosphere deposited by overturning gravity waves. Gravity wave momentum flux is believed to be the engine of a

  15. The Climatology of Polar Mesospheric Clouds From the Student Nitric Oxide Explorer

    NASA Astrophysics Data System (ADS)

    Bailey, S. M.; Thomas, G. E.; Merkel, A. W.

    2001-05-01

    Polar Mesospheric Clouds (PMCs) are a high latitude phenomenon known to occur at altitudes near 83 km at times near the summer solstice, and are related to the phenomenon of Noctilucent Clouds (NLCs). The first recorded siting of an NLC occurred in 1885 and there is evidence that the frequency of occurrence of NLCs is increasing, suggesting long term change in the mesosphere. The first climatology of PMCs was derived from observations by the Solar Mesospheric Explorer (SME) made during 1981 through 1986. SME observations showed seasonal variations with a typical PMC season lasting from approximately 90 days beginning 21 days before summer solstice. The Student Nitric Oxide Explorer (SNOE), like SME, observes the Earth's UV limb radiance and thus also observes PMCs. The instrumentation on SNOE and SME are nearly identical making the observations comparable. SNOE was launched on February 27, 1998; thus, the combination of SNOE and SME measurements cover a span of nearly two decades. To date, SNOE has observed three northern and three southern PMC seasons. In this talk we will present the algorithms for determining PMC scattering properties from the background limb radiance. We will present the derived rates of occurrence of PMCs from the SNOE measurements, and we will show how the variation of cloud brightness and latitudinal extent vary through the season. These results will be compared to those from SME.

  16. Highlights of the MaCWAVE program to study the polar mesosphere

    NASA Astrophysics Data System (ADS)

    Goldberg, R. A.; Fritts, D. C.

    MaCWAVE M ountain A nd C onvective W aves A scending Ve rtically was a highly coordinated rocket ground-based and satellite program designed to address gravity wave forcing of the mesosphere and lower thermosphere MLT The MaCWAVE program was conducted at the Norwegian And o ya Rocket Range ARR 69 3 r N in July 2002 and continued at the Swedish Rocket Range ESRANGE 67 9 r N during January 2003 Correlative instrumentation included the ALOMAR MF and MST radars and RMR and Na lidars ESRANGE MST and meteor radars and RMR lidar radiosondes and TIMED satellite measurements of thermal and constituent structures The data have been used to define the wave field structure fluxes and turbulence generation leading to forcing of the large-scale flow down to a description of small-scale turbulence In summer launch sequences coupled with ground-based measurements at ARR addressed the forcing of the summer mesopause environment by anticipated convective and shear generated gravity waves The summer program demonstrated that the mean state of the upper mesosphere was unusually warm slowing the formation of Polar Mesospheric Summer echoes PMSE and noctilucent clouds NLC The winter program was designed to study the upward propagation and penetration of mountain waves from northern Norway into the MLT at a site favored for such penetration As the major response was expected to be downstream east of Norway these motions were measured with rocket sequences and ground-based instrumentation

  17. A comparison of Polar Mesosphere Summer Echo observations from locations in the Arctic and Antarctica

    NASA Astrophysics Data System (ADS)

    Latteck, Ralph; Sato, Kaoru; Nishimura, Koji; Renkwitz, Toralf

    2017-04-01

    Polar Mesosphere Summer Echoes (PMSE) are observed with 50-MHz VHF radars at various locations in the Northern Hemisphere for more than 20 years. Continuous and homogeneous observations of PMSE have been done on the North-Norwegian island Andøya (69.3°N, 16.0°E) from 1999 until 2009 using the ALWIN radar and since 2011 using the Middle Atmosphere Alomar Radar System (MAARSY) at the same location. In 2011 the PANSY radar - a Mesosphere-Stratosphere-Troposphere/Incoherent Scattering (MST/IS) radar - was installed at Syowa Station, Antartica (69.0°S, 39.4°E) and continues observation of PMSE were started in the austral summer period 2013/2014. Since both MAARSY and PANSY are high-power-large aperture radars mesospheric echoes are observed almost continuously during the summer seasons in the Northern and Southern Hemisphere now. We present a first comparison of PMSE observations obtained at both radar sites during a period of 6 boreal summers (Andøya, NH) and 3 austral summers (Syowa, SH) and discuss similarities and differences of seasonal and diurnal variations of PMSE occurrence frequencies and echo intensity.

  18. Impact of the January 2012 solar proton event on polar mesospheric clouds

    NASA Astrophysics Data System (ADS)

    Bardeen, C. G.; Marsh, D. R.; Jackman, C. H.; Hervig, M. E.; Randall, C. E.

    2016-08-01

    We use data from the Aeronomy of Ice in the Mesosphere mission and simulations using the Whole Atmosphere Community Climate Model to determine the impact of the 23-30 January 2012 solar proton event (SPE) on polar mesospheric clouds (PMCs) and mesospheric water vapor. We see a small heating and loss of ice mass on 26 January that is consistent with prior results but is not statistically significant. We also find a previously unreported but statistically significant ~10% increase in ice mass and in water vapor in the sublimation area in the model that occurs in the 7 to 14 days following the start of the event. The magnitude of the response to the January 2012 SPE is small compared to other sources of variability like gravity waves and planetary waves; however, sensitivity tests suggest that with larger SPEs this delayed increase in ice mass will increase, while there is little change in the loss of ice mass early in the event. The PMC response to SPEs in models is dependent on the gravity wave parameterization, and temperature anomalies from SPEs may be useful in evaluating and tuning gravity wave parameterizations.

  19. Polar Cap Disturbances: Mesosphere and Thermosphere-Ionosphere Response to Solar-Terrestrial Interactions

    NASA Technical Reports Server (NTRS)

    Sivjee, G.; McEwen, D.; Walterscheid, R.

    2003-01-01

    The Polar Cap is the Upper-Atmosphere cum Mag-netosphere region which is enclosed by the poleward boundary of the Auroral Oval and is threaded by open geomagnetic tield lines. In this region, there is normally a steady precipition (Polar "drizzle") of low energy (w 300eV) electrons that excite optical emissions from the ionosphere. At times, enhanced ionization patches are formed near the Dayside Cusp regions that drift across the Polar Cap towards the Night Sector of the Auroral Oval. Discrete auroral arcs and auroras formed during Solar Magnetic Cloud (SMC)/Coronal Mass Ejection (CME) events are also observed in the Polar Cap. Spectrophotometric observations of all these Polar Cap phenomena provide a measure of the average energy as well a energy flux of the electrons precipitating in the Polar Cap region during these disturbances. Such measurements also point to modulations of the Polar Cap Mesosphere-Lower Thermosphere (MLT) air density and temperature by zonally symmetric tides whose Hough functions peak in the Polar region. MLT cooling during Stratospheric Warming events and their relation to Polar Vortex and associated Gravity wave activities are also observed at the Polar Cap sites.

  20. Water Vapor, Temperature, and Ice Particles in Polar Mesosphere as Measured by SABER/TIMED and OSIRIS/Odin Instruments

    NASA Technical Reports Server (NTRS)

    Feofilov, A. G.; Petelina, S. V.; Kutepov, A. A.; Pesnell, W. D.; Goldberg, R. A.

    2009-01-01

    Although many new details on the properties of mesospheric ice particles that farm Polar Mesospheric Clouds (PMCs) and also cause polar mesospheric summer echoes have been recently revealed, certain aspects of mesospheric ice microphysics and dynamics still remain open. The detailed relation between PMC parameters and properties of their environment, as well as interseasonal and interhemispheric differences and trends in PMC properties that are possibly related to global change, are among those open questions. In this work, mesospheric temperature and water vapor concentration measured by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite are used to study the properties of PMCs with respect to the surrounding atmosphere. The cloud parameters, namely location, brightness, and altitude, are obtained from the observations made by the Optical Spectrograph and Infrared Imager System (OSIRIS) on the Odin satellite. About a thousand of simultaneous common volume measurements made by SABER and OSIRIS in both hemispheres from 2002 until 2008 are used. The correlation between PMC brightness (and occurrence rate) and temperatures at PMC altitudes and at the mesopause is analysed. The relation between PMC parameters, frost point temperature, and gaseous water vapor content in and below the cloud is also discussed. Interseasonal and interhemispheric differences and trends in the above parameters, as well as in PMC peak altitudes and mesopause altitudes are evaluated.

  1. Polar mesosphere and lower thermosphere dynamics: 1. Mean wind and gravity wave climatologies

    NASA Astrophysics Data System (ADS)

    Dowdy, Andrew J.; Vincent, Robert A.; Tsutsumi, Masaki; Igarashi, Kiyoshi; Murayama, Yasuhiro; Singer, Werner; Murphy, Damian J.

    2007-09-01

    Mean wind and gravity wave climatologies are presented for the polar mesosphere and lower thermosphere (MLT). The data were derived using MF radars at Davis (69°S, 78°E) and Syowa (69°S, 40°E) in the Antarctic and Poker Flat (65°N, 147°W) and Andenes (69°N, 16°E) in the Arctic. The dynamics of the Antarctic MLT are found to be significantly different from the Arctic MLT. Summer maxima in both the westward and equatorward winds occur closer to the solstice in the Antarctic than in the Arctic. The greater symmetry around the solstice suggests radiative effects may play a greater role in controlling the state of the Antarctic MLT than in the Arctic, where dynamical effects appear to be more important. Gravity wave observations also suggest that wave drag may be greater in the Arctic than in the Antarctic. The equatorward flow near the mesopause persists later in summer in the Arctic than in the Antarctic, as do observations of polar mesospheric clouds and polar mesospheric summer echoes. All three phenomena begin at about the same time in each hemisphere, but end later in the Arctic than in the Antarctic. It is proposed that the magnitude of the meridional winds can be used as a proxy for gravity wave driving and the consequent adiabatic cooling in the MLT. Seasonal variations in gravity wave activity are predominately combinations of annual and semiannual components. Significant hemispheric differences are observed for both the timing and magnitude of these seasonal variations.

  2. First modulation of high-frequency polar mesospheric summer echoes by radio heating of the ionosphere

    NASA Astrophysics Data System (ADS)

    Senior, A.; Mahmoudian, A.; Pinedo, H.; La Hoz, C.; Rietveld, M. T.; Scales, W. A.; Kosch, M. J.

    2014-08-01

    The first high-frequency (HF, 8 MHz) observations of the modulation of polar mesospheric summer echoes (PMSE) by artificial radio heating of the ionosphere are presented and compared to observations at 224 MHz and model predictions. The experiments were performed at the European Incoherent Scatter facility in northern Norway. It is shown that model results are in qualitative and partial quantitative agreement with the observations, supporting the prediction that with certain ranges of ice particle radii and concentration, PMSE at HF radar wavelengths can be enhanced by heating due to the dominance of dust charging over plasma diffusion.

  3. Polar mesosphere summer echo observations at HF frequencies using the HAARP Gakona Ionospheric Observatory

    NASA Astrophysics Data System (ADS)

    Kelley, Michael C.; Huaman, Mercedes; Chen, Charlie Y.; Ramos, Camilo; Djuth, Frank; Kennedy, Edward

    2002-06-01

    We present initial polar mesosphere summer echo (PMSE) observations over Alaska in the HF band. Echoes were detected near 85 km over 50% of the observation time even though it was late in the PMSE season. The signal-to-noise ratio sometimes exceeded 25 dB. We also present the effects of different transmitted powers and antenna pointing directions on PMSE strength and occurrence. There is some evidence that using 4.5 MHz electron heating occurred, even at the low duty cycle used.

  4. Three-satellite comparison of polar mesospheric clouds: Evidence for long-term change

    NASA Astrophysics Data System (ADS)

    Shettle, E. P.; Thomas, G. E.; Olivero, J. J.; Evans, W. F. J.; Debrestian, D. J.; Chardon, L.

    2002-06-01

    Measurements of polar mesospheric clouds (PMCs) from three different satellite instruments are compared. These instruments are the Solar Mesospheric Explorer (SME), the Wind Imaging Interferometer (WINDII), and the Polar Ozone and Aerosol Measurement (POAM II). These measurements have been put on a common basis, correcting for differences in the wavelengths and measurement techniques used. This common basis is the probability distribution of the excess extinction ratio (EER) at a standard wavelength of 265 nm, where the EER is the ratio of the PMC extinction coefficient to the background molecular Rayleigh scattering coefficient. The results indicate that the POAM and WINDII measurements in the Southern Hemisphere had a higher probability of observing bright PMCs during the 1993-1996 time period than SME did a decade earlier in 1983-1986. Local time variations identified in WINDII data are interpreted in terms of a diurnal and semidiurnal component of average EER. These results are qualitatively similar to those found from lidar soundings of noctilucent cloud at sites in Norway and at the South Pole. Differences in interannual variability, local time of the measurements, assumed particle size distributions, and solar cycle effects are ruled out as possible explanations of the differences.

  5. Dusty space plasma diagnosis using temporal behavior of polar mesospheric summer echoes during active modification

    NASA Astrophysics Data System (ADS)

    Mahmoudian, A.; Scales, W. A.; Kosch, M. J.; Senior, A.; Rietveld, M.

    2011-11-01

    The objective of this paper is to study the effect of different plasma and dust parameters on Polar Mesospheric Summer Echoes (PMSE) temporal behavior after turn-on and turn-off of radio wave heating and to use these responses to diagnose the properties of the dust layer. The threshold radar frequency and dust parameters for the enhancement or suppression of radar echoes after radio wave heating turn-on are investigated for measured mesospheric plasma parameters. The effect of parameters such as the electron temperature enhancement during heating, dust density, dust charge polarity, ion-neutral collision frequency, electron density and dust radius on the temporal evolution of electron irregularities associated with PMSE are investigated. The possible diagnostic information for various charged dust and background plasma quantities using the temporal behavior of backscattered radar power in active experiments is discussed. The computational results are used to make predictions for PMSE active modification experiments at 7.9, 56, 139, 224 and 930 MHz corresponding to existing radar facilities. Data from a 2009 VHF (224 MHz) experiment at EISCAT is compared with the computational model to obtain dust parameters in the PMSE.

  6. Calibration of a Rocket-borne Probe for Aerosol Particles in the Polar Mesosphere

    NASA Astrophysics Data System (ADS)

    Knappmiller, S.; Robertson, S.; Sternovsky, Z.; Horanyi, M.

    2006-12-01

    An instrument has been developed to detect charged, sub-visible aerosol particles in the polar mesosphere. This instrument has a 30 square centimeter entrance slit that admits a continuous flow of air. Venting ports are placed lower on the detector in order to let the air out and reduce pressure buildup. The air sample flows between four pairs of graphite electrodes biased symmetrically with increasing bias potentials. Electrons, light ions, cluster ions and heavy charged aerosol particles of both polarities are collected mass-selectively on the electrodes that are connected to sensitive electrometers. Direct Simulation Monte Carlo (DSMC) codes have been used to optimize the supersonic airflow within and around the instrument. A laboratory prototype of the instrument has been fabricated and calibrated using low energy ion beams. The calibration shows that the mass ranges that are collected by the plates are approximately those from the simulations. Two of these instruments are scheduled for launch in the summer of 2007 from Andoya, Norway. These in-situ measurements are planned to coincide with measurements by the Aeronomy of Ice in the Mesosphere (AIM) satellite. Acknowledgement: The project is supported by NASA.

  7. Effect of Gravity Waves Generated in the Monsoon Region on Polar Mesospheric Clouds

    NASA Astrophysics Data System (ADS)

    Thurairajah, B.; Bailey, S. M.; Carstens, J. N.; Siskind, D. E.

    2015-12-01

    Gravity Waves (GWs) play an important role in both the formation and destruction of polar mesospheric clouds. In summer, while vertically propagating GWs induce a residual circulation that cools the summer mesosphere and therefore supports the formation of PMCs, observation and modeling studies have also shown that short period GWs can additionally destroy PMCs. In this study we analyze the effect of non-vertical propagation of GWs on PMCs using temperature data from the SABER instrument on TIMED satellite and PMC occurrence frequency from the CIPS instrument on the AIM satellite. During the 2007 PMC season, time series of GWs over the monsoon region at 50 km and PMCs over the polar region at 84 km have a correlation coefficient of 0.9. SABER GW amplitude and momentum flux over the monsoon region show a poleward tilt with altitude. This slanted structure suggests a poleward, but non-vertical, propagation of GWs facilitated by the easterly winds associated with the monsoon circulation, thus indicating a possible source of high latitude middle atmospheric GWs.

  8. Electron-ion temperature ratio estimations in the summer polar mesosphere when subject to HF radio wave heating

    NASA Astrophysics Data System (ADS)

    Pinedo, H.; La Hoz, C.; Havnes, O.; Rietveld, M.

    2014-10-01

    We have inferred the electron temperature enhancements above mesospheric altitudes under Polar Mesospheric Summer Echoes (PMSE) conditions when the ionosphere is exposed to artificial HF radio wave heating. The proposed method uses the dependence of the radar cross section on the electron-to-ion temperature ratio to infer the heating factor from incoherent scatter radar (ISR) power measurements above 90 km. Model heating temperatures match our ISR estimations between 90 and 130 km with 0.94 Pearson correlation index. The PMSE strength measured by the MORRO MST radar is about 50% weaker during the heater-on period when the modeled electron-to-ion mesospheric temperature is approximately 10 times greater than the unperturbed value. No PMSE weakening is found when the mesospheric temperature enhancement is by a factor of three or less. The PMSE weakening and its absence are consistent with the modeled mesospheric electron temperatures. This consistency supports to the proposed method for estimating mesospheric electron temperatures achieved by independent MST and ISR radar measurements.

  9. The influence of geomagnetic activity on mesospheric summer echoes in middle and polar latitudes

    NASA Astrophysics Data System (ADS)

    Zeller, O.; Bremer, J.

    2009-02-01

    The dependence of mesospheric VHF radar echoes during summer months on geomagnetic activity has been investigated with observation data of the OSWIN radar in Kühlungsborn (54° N) and of the ALWIN radar in Andenes (69° N). Using daily mean values of VHF radar echoes and of geomagnetic activity indices in superimposed epoch analyses, the comparison of both data sets shows in general stronger radar echoes on the day of the maximum geomagnetic activity, the maximum value one day after the geomagnetic disturbance, and enhanced radar echoes also on the following 2-3 days. This phenomenon is observed at middle and polar latitudes and can be explained by precipitating particle fluxes during the ionospheric post storm effect. At polar latitudes, the radar echoes decrease however during and one day after very strong geomagnetic disturbances. The possible reason of this surprising effect is discussed.

  10. Polar Mesospheric Clouds (PMCs) Observed by the Ozone Monitoring Instrument (OMI) on Aura

    NASA Technical Reports Server (NTRS)

    DeLand, Matthew T.; Shettle, Eric P.; Levelt, Pieternel F.; Kowalewski, Matthew G.

    2010-01-01

    Backscattered ultraviolet (BUV) instruments designed for measuring stratospheric ozone profiles have proven to be robust tools for observing polar mesospheric clouds (PMCs). These measurements are available for more than 30 years, and have been used to demonstrate the existence of long-term variations in PMC occurrence frequency and brightness. The Ozone Monitoring Instrument (OMI) on the EOS Aura satellite provides new and improved capabilities for PMC characterization. OMI uses smaller pixels than previous BUV instruments, which increases its ability to identify PMCs and discern more spatial structure, and its wide cross-track viewing swath provides full polar coverage up to 90 latitude every day in both hemispheres. This cross-track coverage allows the evolution of PMC regions to be followed over several consecutive orbits. Localized PMC variations determined from OMI measurements are consistent with coincident SBUV/2 measurements. Nine seasons of PMC observations from OMI are now available, and clearly demonstrate the advantages of these measurements for PMC analysis.

  11. Extreme stratospheric springs and their consequences for the onset of polar mesospheric clouds

    NASA Astrophysics Data System (ADS)

    Siskind, David E.; Allen, Douglas R.; Randall, Cora E.; Harvey, V. Lynn; Hervig, Mark E.; Lumpe, Jerry; Thurairajah, Brentha; Bailey, Scott M.; Russell, James M.

    2015-09-01

    We use data from the Aeronomy of Ice in the Mesosphere (AIM) explorer and from the NASA Modern Era Retrospective Analysis for Research and Applications (MERRA) stratospheric analysis to explore the variability in the onset of the Northern Hemisphere (NH) Polar Mesospheric Cloud (PMC) season. Consistent with recently published results, we show that the early onset of the NH PMC season in 2013 was accompanied by a warm springtime stratosphere; conversely, we show that the late onset in 2008 coincides with a very cold springtime stratosphere. Similar stratospheric temperature anomalies for 1997 and 2011 also are connected either directly, through observed temperatures, or indirectly, through an early PMC onset, to conditions near the mesopause. These 4 years, 2008, 1997, 2011, and 2013 represent the extremes of stratospheric springtime temperatures seen in the MERRA analysis and correspond to analogous extrema in planetary wave activity. The three years with enhanced planetary wave activity (1997, 2011 and 2013) are shown to coincide with the recently identified stratospheric Frozen In Anticyclone (FrIAC) phenomenon. FrIACs in 1997 and 2013 are associated with early PMC onsets; however, the dramatic FrIAC of 2011 is not. This may be because the 2011 FrIAC occurred too early in the spring. The link between NH PMC onset and stratospheric FrIAC occurrences represents a new mode of coupling between the stratosphere and mesosphere. Since FrIACs appear to be more frequent in recent years, we speculate that as a result, PMCs may occur earlier as well. Finally we compare the zonal mean zonal winds and observed gravity wave activity for the FrIACs of 2011 and 2013. We find no evidence that gravity wave activity was favored in 2013 relative to 2011, thus suggesting that direct forcing by planetary waves was the key mechanism in accelerating the cooling and moistening of the NH mesopause region in May of 2013.

  12. 3D measurements in the polar mesosphere using coherent radar imaging

    NASA Astrophysics Data System (ADS)

    Zecha, M.; Sommer, S.; Rapp, M.; Stober, G.; Latteck, R.

    2012-12-01

    Radars provide the opportunity of continuous measurements in the interesting area of the polar mesosphere. Usually the spatial resolution of measurements by pulsed VHF radars is limited by the radar beam width, transmitting pulse length, and sampling time. Due to these technical restrictions the typical small-scale structures in the mesosphere often cannot be resolved. Furthermore the quality of the estimation of dynamic atmosphere parameters is reduced if the position and direction of scatter returns cannot determined exactly. Radar interferometry methods have been developed to reduce these limitations. The coherent radar imaging method gives a high resolving image of the scatter structure insight the radar beam volume. In recent years the VHF radar MAARSY was installed in Andenes/Norway (69°N). This new radar was designed to allow improved three-dimensional observations in the atmosphere. It consists of 433 Yagis and allows a minimum beam width of about 4 degree. The beam direction can be changed pulse-by-pulse freely in azimuth angle and practicable up to 40 degree in zenith angle. The pulse length can be varied from a couple of km down to 50 m. Up to 16 receiving channels of spaced antennas can be used. In this presentation we show the detection of the angles-of-arrival of radar echoes and the correction of the wind measurements. We demonstrate the improvement of measurement results by using coherent radar imaging. The differences to the results of conventional methods depend on the beam width, range resolution, antenna distances, and beam tilting. We show that the application of interferometry is necessary to improve considerably the quality of 3D-measurement results. Furthermore we demonstrate the synthesis of high resolved images to get a real 3D image of the mesosphere.

  13. Comparison of Satellite and Ground-based Measurements of Polar Mesospheric Clouds

    NASA Astrophysics Data System (ADS)

    Barker-Tvedtnes, J.; Taylor, M.; Deland, M.

    2008-12-01

    Polar Mesospheric Clouds (PMCs) are tenuous ice clouds that form near the cold (<150K) summer mesopause region (80-85 km). From the ground, these clouds are seen during twilight hours as Noctilucent or "night shining" Clouds (NLCs) and are typically seen from latitudes from 50° to 65°. Observations by the Solar Backscatter Ultraviolet (SBUV) instruments on the NOAA satellites have shown that the occurrence and brightness of NLCs have been increasing over the last several decades prompting speculation concerning their possible role in climate change. Recently the Aeronomy of Ice in the Mesosphere (AIM) satellite was launched (April 2007) and is the first satellite dedicated to the study of NLCs. In this presentation, we compare SBUV and AIM PMC observations with ground-based image data collected during two campaigns from Edmonton, Canada (June 30-July 17, 2007) and Delta Junction, Alaska (July 29- August 17, 2007). Four nights of data are presented where coincident measurements were obtained by AIM, SBUV and ground-based imagers. The results show good spatial or temporal agreement, but rarely both, and illustrate the importance of coordinated measurements for better understanding the geographic and local time variability of PMCs.

  14. Gravity waves in polar mesospheric clouds measured by Odin/OSIRIS since 2002

    NASA Astrophysics Data System (ADS)

    Petelina, S. V.

    2009-05-01

    The Optical Spectrograph and InfraRed Imager System instrument (OSIRIS) on the limb-viewing Odin satellite observes Polar Mesospheric Clouds (PMCs) in both hemispheres since November, 2001. The orbit period of Odin is 96 minutes and the maximum latitudinal coverage in the orbit plane is between 82.2 N and 82.2 S. In this work, the longitudinal distribution of Odin/OSIRIS PMC brightness in each hemisphere during a 4-week period around the summer solstice from 2002 until 2009 is analyzed. It is found that in the southern hemisphere, the cloud brightness was consistently up to 30% lower around 250-300°E (70-120°W) - above the Antarctic peninsular. In the northern hemisphere, the PMC brightness was systematically 20-30% lower around 50-130°E - above Ural Mountains. Similar results have been obtained for the PMC 2007-08 season in Antarctica and PMC-2007 Arctic season by one of the instruments on a recently launched Aeronomy of Ice in the Mesosphere (AIM) satellite. We attribute this effect to the influence of gravity waves generated by the Earth's terrain.

  15. Polar mesosphere and lower thermosphere dynamics: 2. Response to sudden stratospheric warmings

    NASA Astrophysics Data System (ADS)

    Dowdy, Andrew J.; Vincent, Robert A.; Tsutsumi, Masaki; Igarashi, Kiyoshi; Murayama, Yasuhiro; Singer, Werner; Murphy, Damian J.; Riggin, D. M.

    2007-09-01

    The dynamical response of the polar mesosphere and lower thermosphere (MLT) to sudden stratospheric warmings is investigated using MF radars at Davis (69°S, 78°E), Syowa (69°S, 40°E) and Rothera (68°S, 68°W) in the Antarctic and Poker Flat (65°N, 147°W) and Andenes (69°N, 16°E) in the Arctic. Mean winds, gravity waves and planetary waves are investigated during sudden stratospheric warmings, and comparisons are made with climatological means. The available MF radar data set includes six major sudden stratospheric warmings in the Northern Hemisphere and the unprecedented 2002 Southern Hemisphere major stratospheric warming. Three of the six northern events are relatively weak and could almost be classed as minor warmings, while the larger three have similar characteristics to the event in the Southern Hemisphere. Zonal wind reversals associated with the major warmings in both hemispheres are generally weaker and earlier by several days in the mesosphere than in the stratosphere. There are, however, significant differences between locations in their response to stratospheric warmings. The zonal winds are remarkably weaker than average during both winter and spring around the time of the southern major warming of 2002, but these effects are not observed for the Northern Hemisphere events. Gravity wave activity is found to vary significantly between individual stratospheric warming events and also between individual locations.

  16. Thermodynamics of polarized relativistic matter

    NASA Astrophysics Data System (ADS)

    Kovtun, Pavel

    2016-07-01

    We give the free energy of equilibrium relativistic matter subject to external gravitational and electromagnetic fields, to one-derivative order in the gradients of the external fields. The free energy allows for a straightforward derivation of bound currents and bound momenta in equilibrium. At leading order, the energy-momentum tensor admits a simple expression in terms of the polarization tensor. Beyond the leading order, electric and magnetic polarization vectors are intrinsically ambiguous. The physical effects of polarization, such as the correlation between the magneto-vortically induced surface charge and the electro-vortically induced surface current, are not ambiguous.

  17. A Review of Recent Lidar Studies of the Diurnal and Seasonal Variations of Polar Mesospheric Clouds

    NASA Astrophysics Data System (ADS)

    Gardner, C. S.; Chu, X.

    2001-05-01

    Lidar observations during the past decade have contributed enormously to our understanding of the structure of polar mesospheric clouds. Multi-wavelength observations have provided key insights into the size distribution and concentration of the PMC particles while 24 hour measurements have revealed the strong influence of tidal perturbations on the height and volume backscatter properties of the cloud layers. We summarize pioneering observations in the Northern Hemisphere at Andoya, Norway and Sondrestromfjord, Greenland. We also discuss seasonal trends emerging from the first lidar measurments of PMCs in the Southern Hemisphere. These data, obtained at the Amundsen-Scott South Pole Station, provide new insights into possible hemispherical differences in mesopause region dynamics and temperature structure.

  18. On the angular dependence and scattering model of polar mesospheric summer echoes at VHF

    NASA Astrophysics Data System (ADS)

    Sommer, Svenja; Stober, Gunter; Chau, Jorge L.

    2016-01-01

    We present measurements of the angular dependence of polar mesospheric summer echoes (PMSE) with the Middle Atmosphere Alomar Radar System in Northern Norway (69.30° N, 16.04° E). Our results are based on multireceiver and multibeam observations using beam pointing directions with off-zenith angles up to 25° as well as on spatial correlation analysis (SCA) from vertical beam observations. We consider a beam filling effect at the upper and lower boundaries of PMSE in tilted beams, which determines the effective mean angle of arrival. Comparing the average power of the vertical beam to the oblique beams suggests that PMSE are mainly not as aspect sensitive as in contrast to previous studies. However, from SCA, times of enhanced correlation are found, indicating aspect sensitivity or a localized scattering mechanism. Our results suggest that PMSE consist of nonhomogeneous isotropic scattering and previously reported aspect sensitivity values might have been influenced by the inhomogeneous nature of PMSE.

  19. Studies of Polar Mesosphere Summer Echoes by VHF radar and rocket probes

    NASA Technical Reports Server (NTRS)

    Hoppe, U. -P.; Blix, T. A.; Thrane, E. V.; Lubken, F. -J.; Cho, J. Y. N.; Swartz, W. E.

    1994-01-01

    At radar frequencies in the range 50 MHz to 250 MHz, at times even to over 1 GHz, strong enhancements of scattering cross section occur between approximately equal to 80 km and approximately 95 km altitude in summer at high latitudes. These echoes, termed 'Polar Mesosphere Summer Echoes' (PMSE) have attracted considerable experimental effort. Observations of this phenomenon are reviewed in the context of atmospheric dynamics and of scattering processes. Recent rocket and radar measurements indicate that a partial reflection from a multitude of ion layers and constructive interference causes at least some of the PMSE. It is discussed which further observations are necessary and some possible practical consequences of PMSE are pointed out.

  20. Local time dependence of polar mesospheric clouds and model validation with satellite data

    NASA Astrophysics Data System (ADS)

    Schmidt, Francie; Berger, Uwe; Lübken, Franz-Josef

    2016-04-01

    Polar mesospheric clouds (PMCs), also known as noctilucent clouds (NLCs), consist of water-ice cystals. They occur at high latitudes in the summer mesopause region at very low temperatures below 150 K. In this case PMCs are highly sensitive to atmospheric conditions. Therefore, PMCs are thought to be sensitive indicators of climate changes in the middle atmosphere. The ice clouds show spatial and temporal variations. We present a model that can help to understand the variability of mesospheric clouds. The model is called Mesospheric Ice Microphysics And tranSport model (MIMAS) and is a threedimensional Lagrangian transport model, which can be used on multiple dynamic fields. MIMAS is a good instrument to check observations and also to fill some gaps that are included in satellite observations, e.g., the local time dependence of PMCs. The ice model is used to study local time dependencies of the PMC occurrence frequency, brightness and ice water content. At the station ALOMAR in Northern Norway (69°N, 16°E) we have the most ice water content with a total mean of around 90 g/km² (July 2008) in the morning hours. In the afternoons the ice water content decreases to 10 g/km² and increases again in the evening hours to 50 g/km². Tidal variability will impact results of long-term PMC observations which do not cover the full diurnal cycle. To investigate the local time dependence of PMCs in its entirety, ground-based remote sensing instruments, e.g., lidars are usefull. Variations in PMCs relating to occurrence frequency and brightness as function of local time had been already observed with the ALOMAR Rayleigh/Mie/Raman lidar. But lidar measurements offer only observations at a single local station. Models give the opportunity of a global perspective on a possible local time dependence of PMCs. In this context we will present latitudinal variations regarding to local time dependence. The combination of further observations and modeling studies can help to understand

  1. Characterization of High Frequency Polar Mesospheric Summer Echoes during Heating Experiments

    NASA Astrophysics Data System (ADS)

    Scales, Wayne; Mahmoudian, Alireza

    It has been experimentally observed for some time now that the Polar Mesospheric Summer Echo PMSE strength can be artificially modified by using a ground-based ionospheric heating facility to perturb the electron irregularity source region that is believed to produce PMSE. It is evident that significant diagnostic information may be available to characterize the charged sub-visible dust layer from the temporal behavior of the electron irregularities during the heating process which ultimately modifies the mesospheric electron temperature. Particularly impor-tant time periods of the irregularity temporal behavior are during the turn-on and turn-off of the radio wave heating in which interesting and important behavior has been predicted and observed. Most past experiments have been performed using radar measurements in the VHF frequency range, i.e. consideration of VHF PMSE. Recently measurements have begun to be made using HF radars for investigation of heating of HF PMSE. The objective of this presen-tation is to discuss the physical processes that control the evolution of electron irregularities associated with mesospheric dust layers during radio wave heating for these new HF radar measurements. First, the two dominant processes that control electron irregularity evolution during ionospheric heating, dust charging and ambipolar diffusion will be discussed. It will be shown that a fundamental parameter that controls the temporal behavior is the ratio of the dust charging to ambipolar diffusion time during the turn-on and turn-off period. Computational and analytical models will be introduced that may be used to directly investigate the electron irregularity temporal evolution with particular emphasis placed on modeling the electron ir-regularity temporal evolution during the time periods when the radio wave heating is turned on and off. These models will be used to investigate the evolution predicted for measurements with HF radars. Guided by the results, possible

  2. Layered Polar Mesospheric Summer Echoes Observed with the Tri-Static Eiscat VHF

    NASA Astrophysics Data System (ADS)

    Mann, I.; Anyairo, C.; Häggström, I.; Tjulin, A.

    2014-12-01

    Polar mesospheric summer echoes (PMSE) are strong radar echoes that are typically observed at 50 to 500 MHz. They are often discussed in the context of dusty plasma studies and linked to e.g. the existence of charged ice particles, neutral atmospheric turbulence and atmospheric stratification. The PMSE are observed at mesospheric temperature minimum when ice particles form, though the exact path of formation is still a topic for research. Mesospheric smoke particles that are assumed to form after or during the meteor ablation process possibly contribute to the formation of the ice particles. For understanding the formation of the radar echoes their variation with scattering angle is an important parameter. We analyze PMSE observations with the tri-static EISCAT VHF radar (224 MHz) during one day in June when PMSE were observed almost continuously from 7:00 to 13:00 UT. The radar signal was transmitted and received in zenith direction with the EISCAT VHF antenna near Tromsø. The receivers in Kiruna and Sodankylä were pointed at typical PMSE heights above the Tromsø transmitter and detected radar reflections at the same time and altitude as the Tromsø radar. The altitude of the PMSE changed with time and the extension of the echoes in altitude was smaller toward the end of the observation. These observations are among the first tri-static observations of PMSE. The observations suggest that the scattering process underlying the PMSE occurs over a broad range of scattering angles. Based on the observations we will show that the spectral width of the received echoes is most likely determined by the variations within the observed volume rather than by the scattering process. The observed frequency shifts suggest a layer structure and horizontal motions that vary with altitude. UHF (933 MHz) radar observations were carried out in parallel, they display predominantly incoherent scatter and an electron density typical for the altitude. Some other studies, have in

  3. Solar-induced 27-day variations of mesospheric temperature and water vapor from the AIM SOFIE experiment: Drivers of polar mesospheric cloud variability

    NASA Astrophysics Data System (ADS)

    Thomas, Gary E.; Thurairajah, Brentha; Hervig, Mark E.; von Savigny, Christian; Snow, Martin

    2015-11-01

    Polar Mesospheric Clouds (PMCs) are known to be influenced by changes in water vapor and temperature in the cold summertime mesopause. Solar variability of these constituents has been held responsible for 11-year and 27-day variability of PMC activity, although the detailed mechanisms are not yet understood. It is also known that the solar influence on PMC variability is a minor contributor to the overall day-to-day variability, which is dominated by effects of gravity waves, planetary waves, and inter-hemispheric coupling. To address this issue, we have analyzed 15 seasons of data taken from the Solar Occultation for Ice Experiment (SOFIE) on the Aeronomy of Ice in the Mesosphere (AIM) satellite. The SOFIE data contain precise measurements of water vapor, temperature and ice water content (among other quantities). These high-latitude measurements are made during the PMC season at the terminator, and therefore directly relate to the simultaneous measurements of mesospheric ice. Using a composite data set of Lyman-α irradiance, we correlated the time variation of the atmospheric variables with the 27-day variability of solar ultraviolet irradiance. We used a combination of time-lagged linear regression and Superposed Epoch Analysis to extract the solar contribution as sensitivity values (response/forcing) vs. height. We compare these results to previously published results, and show that the temperature sensitivity is somewhat higher, whereas the water sensitivity is nearly the same as published values. The time lags are shorter than that expected from direct solar heating and photodissociation, suggesting that the responses are due to 27-day variations of vertical winds. An analytic solution for temperature changes forced by solar irradiance variations suggests that if the response is due purely to Lyman-α heating and Newtonian cooling, the response should vary throughout the summertime season and depend primarily upon the height-dependent column density of

  4. Rocket-borne Probes for Aerosol Particles in the Polar Mesosphere

    NASA Astrophysics Data System (ADS)

    Robertson, S.; Knappmiller, S.; Sternovsky, Z.; Horanyi, M.

    2006-05-01

    Two instruments have been developed to detect charged aerosol particles in the mesosphere. The first is a flat charge-collecting graphite surface on the skin of the rocket that has returned data in several sounding rocket campaigns. The collection surfaces have permanent magnets behind them to provide shielding from electrons, and have a positive voltage bias that repels light ions. Probes with and without an electric bias were launched in January 2005 from Esrange, Sweden, as a part of the MAGIC campaign. The probes detected a distinct layer of positive aerosols at around 82 km altitude. A second instrument has been developed to detect charged, sub-visible aerosol particles in the upper atmosphere. This instrument has a 30 square centimeter entrance slit that admits a continuous flow of air. Venting ports are placed lower on the detector in order to let the air out and reduce pressure buildup. The air sample flows between four pairs of graphite electrodes biased symmetrically with increasing bias potentials. Electrons, light ions, cluster ions and heavy charged aerosol particles of both polarities are collected mass-selectively on the electrodes that are connected to sensitive electrometers. Direct Simulation Monte Carlo (DSMC) codes have been used to optimize the supersonic airflow within and around the instrument. A laboratory prototype of the instrument has been fabricated and calibrated using low energy ion beams. Two of these instruments are scheduled for launch in the summer of 2007 from Andoya, Norway. These in-situ measurements are planned to coincide with measurements by the Aeronomy of Ice in the Mesosphere (AIM) satellite.

  5. First Measurements of Aspect Sensitivity of Polar Mesospheric Summer Echoes by a Bistatic Radar System

    NASA Astrophysics Data System (ADS)

    La Hoz, C.; Pinedo, H.; Havnes, O.; Kosch, M. J.; Senior, A.; Rietveld, M. T.

    2014-12-01

    Polar Mesospheric Summer Echoes (PMSE) have been observed for the first time by a bistatic radar system comprising the EISCAT VHF (224 MHz) active radar in Tromso (Norway) and the receiving EISCAT_3D demonstrator array located in Kiruna, (Sweden). The receiving system is 234 km southeast from the transmitting radar and its line of sight to the mesosphere above Tromso has an elevation angle of 21 degrees implying an aspect angle of the scattered signals in that direction of 69 degrees. This is the first time that a truly bistatic configuration has been employed to measure the angle dependence of the scattering mechanism of PMSE which otherwise has been measured only in monostatic configurations. The bistatic configuration is unencumbered by drawbacks of the monostatic configuration that cannot reach angles greater than about 20 degrees due to antenna beam pattern degradation and the use of models to extrapolate the angle dependence of the scattered signals. Strong scattering was observed over prolonged periods on several days by the demonstrator array in July of 2011. These measurements are at variance with previous aspect angle measurements that have reported aspect angles no greater than about 15 degrees. These results indicate that the turbulent irregularities that produce the scattering have a high degree of isotropy, which is more in line with Kolmogorov's hypothesis of a universal scaling of turbulence based on the assumption of homogeneity and isotropy in the inertial regime of turbulence which applies also to the Batchelor regime (due to large Schmidt numbers) believed to be the case for PMSE.

  6. Similarities and differences in polar mesosphere summer echoes observed in the Arctic and Antarctica

    NASA Astrophysics Data System (ADS)

    Latteck, R.; Singer, W.; Morris, R. J.; Hocking, W. K.; Murphy, D. J.; Holdsworth, D. A.; Swarnalingam, N.

    2008-09-01

    Polar Mesosphere Summer Echoes (PMSE) have been observed in the high latitudes of the Northern and Southern Hemisphere for several years using VHF radars located at Andenes/Norway (69° N, 16° E), Resolute Bay/Canada (75° N, 95° W), and Davis/Antarctica (69° S, 78° E). The VHF radars at the three sites were calibrated using the same methods (noise source and delayed transmitting signal) and identical equipment. Volume reflectivity was derived from the calibrated echo power and the characteristics of the seasonal variation of PMSE were estimated at the sites for the years 2004 to 2007. The largest peak volume reflectivity of about 2×10-9 m-1 was observed at Andenes compared with their counterparts at Davis (~4×10-11 m-1) and Resolute Bay (~6×10-12 m-1). The peak of the PMSE height distribution is 85.6 km at Davis which is about 1 km higher than at Andenes. At Resolute Bay the height distribution peaks at about 85 km but only a few layers were found below 84 km. The mean PMSE occurrence rate is 83% at Andenes, 38% at Davis with larger variability and only 18% at Resolute Bay (in late summer). The duration of the PMSE season varies at Andenes from 104 to 113 days and at Davis from 88 to 93 days. In general the PMSE seasons starts about 5 days later at Davis and ends about 10 days earlier compared to Andenes. In all three seasons the PMSE occurrence suddenly drops to a much lower level at Davis about 32 days after solstice whereas the PMSE season decays smoothly at Andenes. The duration of the PMSE season at Andenes and Davis is highly correlated with the presence of equatorward directed winds, the observed differences in PMSE occurrence are related to the mesospheric temperatures at both sites.

  7. Persistent longitudinal variations in 8 years of CIPS/AIM polar mesospheric clouds

    NASA Astrophysics Data System (ADS)

    Liu, Xiao; Yue, Jia; Xu, Jiyao; Yuan, Wei; Russell, James M.; Hervig, M. E.; Nakamura, Takuji

    2016-07-01

    The Cloud Imaging and Particle Size (CIPS) instrument on the Aeronomy of Ice in the Mesosphere (AIM) satellite provides an opportunity to study the longitudinal variation in polar mesospheric cloud (PMC). We examined the longitudinal variation in PMC albedo using 8 years (2007-2014) of observations from the CIPS instrument. The results show that the PMC albedo in the Southern Hemisphere (SH), especially in the latitude band of 80°S-85°S, is persistently low ( 65% relative to the rest of the hemisphere) within 60°W to 150°W longitude. In the Northern Hemisphere (NH), however, PMC albedo is found to be relatively zonally asymmetry. Harmonic analyses show that the persistent longitudinal variation in the SH PMC albedo is due to zonal wave numbers 1 through 4 (WN1-WN4) processes with minima in the longitude range of 60°W-150°W. The influence of temperature and H2O on the longitudinal variation of the PMC albedo is discussed based on results obtained using a simple 0-D PMC model and temperature from the Microwave Limb Sounder (MLS) and the Sounding of the Atmosphere with Broadband Emission Radiometry (SABER) and H2O from MLS. The modeled region of low ice mass in the SH is generally consistent with that of low PMC albedo seen in CIPS. Tidal analyses using the SABER temperatures indicate that the nonmigrating semidiurnal tides with modes of S0, W1, and E1 might be the main drivers of the persistent longitudinal variations of PMC albedo in the SH. Nonmigrating tides are much weaker in the NH and consistent with the observed lack of longitudinal variability in PMC albedo.

  8. Polar summer mesospheric extreme horizontal drift speeds during interplanetary corotating interaction regions (CIRs) and high-speed solar wind streams: Coupling between the solar wind and the mesosphere

    NASA Astrophysics Data System (ADS)

    Lee, Young-Sook; Kirkwood, Sheila; Kwak, Young-Sil; Kim, Kyung-Chan; Shepherd, Gordon G.

    2014-05-01

    We report the observation of echo extreme horizontal drift speed (EEHS, ≥ 300 m s-1) during polar mesospheric (80-90 km) summer echoes (PMSEs) by the VHF (52 MHz) radar at Esrange, Sweden, in years of 2006 and 2008. The EEHS occur in PMSEs as correlated with high-speed solar wind streams (HSSs), observed at least once in 12-17% of all hours of observation for the two summers. The EEHS rate peaks occur either during high solar wind speed in the early part of the PMSE season or during the arrival of interplanetary corotating interaction regions (CIRs) followed by peaks in PMSE occurrence rate after 1-4 days, in the latter part of the 2006 summer. The cause of EEHS rate peaks is likely under the competition between the interval of the CIR and HSS passage over the magnetosphere. A candidate process in producing EEHS is suggested to be localized strong electric field, which is caused by solar wind energy transfer from the interaction of CIR and HSS with the magnetosphere in a sequential manner. We suggest that EEHS are created by strong electric field, estimated as > 10-30 V m-1 at 85 km altitude, exceeding the mesospheric breakdown threshold field.

  9. Observation of Polar Mesosphere Summer Echoes using the Northernmost MST Radar at Eureka (80 deg N)

    NASA Technical Reports Server (NTRS)

    Swarnalingam, N.; Hocking, W.; Janches, D.; Drummond, J.

    2017-01-01

    We investigate long-term Polar Mesosphere Summer Echoes (PMSEs) observations conducted by the northern most geographically located MST radar at Eureka (80 deg N, 86 deg W). While PMSEs are a well recognized summer phenomenon in the polar regions, previous calibrated studies at Resolute Bay and Eureka using 51.5 MHz and33 MHz radars respectively, showed that PMSE backscatter signal strengths are relatively weak in the polar cap sites, compared to the auroral zone sites (Swarnalingam et al., 2009b; Singer et al., 2010). Complications arise with PMSEs in which the echo strength is controlled by the electrons, which are, in turn, influenced by heavily charged ice particles as well as the variability in the D-region plasma. In recent years, PMSE experiments were conducted inside the polar cap utilizing a 51 MHz radar located at Eureka. In this paper, we investigate calibrated observations, conducted during 2009-2015. Seasonal and diurnal variations of the backscatter signal strengths are discussed and compared to previously published results from the ALOMAR radar, which is a radar of similar design located in the auroral zone at Andenes, Norway (69 deg N, 16 deg E). At Eureka, while PMSEs are present with a daily occurrence rate which is comparable to the rate observed at the auroral zone site for at least two seasons, they show a great level of inter-annual variability. The occurrence rate for the strong echoes tends to be low. Furthermore, comparison of the absolute backscatter signal strengths at these two sites clearly indicates that the PMSE backscatter signal strength at Eureka is weak. Although this difference could be caused by several factors, we investigate the intensity of the neutral air turbulence at Eureka from the measurements of the Doppler spectrum of the PMSE backscatter signals. We found that the level of the turbulence intensity at Eureka is weak relative to previously reported results from three high latitude sites.

  10. Wave Driven Disturbances of the Thermal Structure in the Polar Winter Upper Stratosphere and Lower Mesosphere

    NASA Astrophysics Data System (ADS)

    Greer, Katelynn R.

    The polar winter middle atmosphere is a dynamically active region that is driven primarily by wave activity. Planetary waves intermittently disturbed the region at different levels and the most spectacular type of disturbance is a major Sudden Stratospheric Warming (SSW). However, other types of extreme disturbances occur on a more frequent, intraseasonal basis. One such disturbance is a synoptic-scale "weather event" observed in lidar and rocket soundings, soundings from the TIMED/SABER instrument and UK Meteorological Office (MetO) assimilated data. These disturbances are most easily identified near 42 km where temperatures are elevated over baseline conditions by a remarkable 50 K and an associated cooling is observed near 75 km. As these disturbances have a coupled vertical structure extending into the lower mesosphere, they are termed Upper Stratospheric/Lower Mesospheric (USLM) disturbances. This research begins with description of the phenomenology of USLM events in observations and the assimilated data set MetO, develops a description of the dynamics responsible for their development and places them in the context of the family of polar winter middle atmospheric disturbances. Climatologies indicates that USLM disturbances are commonly occurring polar wintertime disturbances of the middle atmosphere, have a remarkably repeating thermal structure, are located on the East side of the polar low and are related planetary wave activity. Using the same methodology for identifying USLM events and building climatologies of these events, the Whole Atmosphere Community Climate Model WACCM version 4 is established to spontaneously and internally generate USLM disturbances. Planetary waves are seen to break at a level just above the stratopause and convergence of the EP-flux vector is occurring in this region, decelerating the eastward zonal-mean wind and inducing ageostrophic vertical motion to maintain mass continuity. The descending air increases the horizontal

  11. 27-day solar forcing of mesospheric temperature, water vapor and polar mesospheric clouds from the AIM SOFIE and CIPS satellite experiments

    NASA Astrophysics Data System (ADS)

    Thomas, Gary; Thurairajah, Brentha; von Savigny, Christian; Hervig, Mark; Snow, Martin

    2016-04-01

    Solar cycle variations of ultraviolet radiation have been implicated in the 11-year and 27-day variations of Polar Mesospheric Cloud (PMC) properties. Both of these variations have been attributed to variable solar ultraviolet heating and photolysis, but no definitive studies of the mechanisms are available. The solar forcing issue is critical toward answering the broader question of whether PMC's have undergone long-term changes, and if so, what is the nature of the responsible long-term climate forcings? One of the principal goals of the Aeronomy of Ice in the Mesosphere satellite mission was to answer the question: "How does changing solar irradiance affect PMCs and the environment in which they form?" We describe an eight-year data set from the AIM Solar Occultation for Ice Experiment (SOFIE) and the AIM Cloud Imaging and Particle Size (CIPS) experiment. Together, these instruments provide high-precision measurements of high-latitude summertime temperature (T), water vapor (H2O), and PMC ice properties for the period 2007-present. The complete temporal coverage of the summertime polar cap region for both the primary atmospheric forcings of PMC (T and H2O), together with a continually updated time series of Lyman-alpha solar irradiance, allows an in-depth study of the causes and effects of 27-day PMC variability. The small responses of these variables, relative to larger day-to-day changes from gravity waves, tides, inter-hemispheric coupling, etc. require a careful statistical analysis to isolate the solar influence. We present results for the 27-day responses of T, H2O and PMC for a total of 15 PMC seasons, (30 days before summer solstice to 60 days afterward, for both hemispheres). We find that the amplitudes and phase relationships are not consistent with the expected mechanisms of solar UV heating and photolysis - instead we postulate a primarily dynamical response, in which a periodic vertical wind heats/cools the upper mesosphere, and modulates PMC

  12. Simulation of particle size distributions in Polar Mesospheric Clouds from Microphysical Models

    NASA Astrophysics Data System (ADS)

    Thomas, G. E.; Merkel, A.; Bardeen, C.; Rusch, D. W.; Lumpe, J. D.

    2009-12-01

    The size distribution of ice particles is perhaps the most important observable aspect of microphysical processes in Polar Mesospheric Cloud (PMC) formation and evolution. A conventional technique to derive such information is from optical observation of scattering, either passive solar scattering from photometric or spectrometric techniques, or active backscattering by lidar. We present simulated size distributions from two state-of-the-art models using CARMA sectional microphysics: WACCM/CARMA, in which CARMA is interactively coupled with WACCM3 (Bardeen et al, 2009), and stand-alone CARMA forced by WACCM3 meteorology (Merkel et al, this meeting). Both models provide well-resolved size distributions of ice particles as a function of height, location and time for realistic high-latitude summertime conditions. In this paper we present calculations of the UV scattered brightness at multiple scattering angles as viewed by the AIM Cloud Imaging and Particle Size (CIPS) satellite experiment. These simulations are then considered discretely-sampled “data” for the scattering phase function, which are inverted using a technique (Lumpe et al, this meeting) to retrieve particle size information. We employ a T-matrix scattering code which applies to a wide range of non-sphericity of the ice particles, using the conventional idealized prolate/oblate spheroidal shape. This end-to-end test of the relatively new scattering phase function technique provides insight into both the retrieval accuracy and the information content in passive remote sensing of PMC.

  13. Tomographic and spectral views on the lifecycle of polar mesospheric clouds from Odin/OSIRIS

    NASA Astrophysics Data System (ADS)

    Hultgren, Kristoffer; Gumbel, Jörg

    2014-12-01

    Vertical and horizontal structures of Polar Mesospheric Clouds (PMC) have been recovered by tomographic retrieval from the OSIRIS instrument aboard the Odin satellite. The tomographic algorithm has been used to return local scattering coefficients at seven wavelengths in the ultraviolet. This spectral information is used to retrieve PMC particle sizes, number density, and ice mass density. While substantial horizontal variations are found, local vertical structures are overall consistent with the idea of a growth-sedimentation process leading to a visible cloud. Large numbers of small particles are present near the top of the observed cloud layer. Toward lower altitudes, particle sizes increase while particle number densities decrease. A close relationship is found between the distribution of local PMC scattering coefficient and ice mass density. The bottom of the cloud often features large particles with mode radii exceeding 70 nm that rain out of the cloud before sublimating. The number density of these large particles is small, and they do not contribute significantly to the overall cloud brightness. As a consequence, the presence of these large particles can be difficult to identify for remote sensing techniques that integrate over the entire cloud column. When it comes to deriving absolute values of particle mode radius and number density, there is a strong sensitivity to assumptions on the mathematical form of the particle size distribution. We see a continued strong need to resolve this issue by co-analysis of various remote sensing techniques and observation geometries.

  14. Double-layer structure in polar mesospheric clouds observed from SOFIE/AIM

    NASA Astrophysics Data System (ADS)

    Gao, Haiyang; Shepherd, Gordon G.; Tang, Yuanhe; Bu, Lingbing; Wang, Zhen

    2017-02-01

    Double-layer structures in polar mesospheric clouds (PMCs) are observed by using Solar Occultation for Ice Experiment (SOFIE) data between 2007 and 2014. We find 816 and 301 events of double-layer structure with percentages of 10.32 and 7.25 % compared to total PMC events, and the mean distances between two peaks are 3.06 and 2.73 km for the Northern Hemisphere (NH) and Southern Hemisphere (SH) respectively. Double-layer PMCs almost always have less mean ice water content (IWC) than daily IWC during the core of the season, but they are close to each other at the beginning and the end. The result by averaging over all events shows that the particle concentration has obvious double peaks, while the particle radius exhibits an unexpected monotonic increase with decreasing altitude. By further analysis of the background temperature and water vapour residual profiles, we conclude that the lower layer is a reproduced one formed at the bottom of the upper layer. 56.00 and 47.51 % of all double-layer events for the NH and SH respectively have temperature enhancements larger than 2 K locating between their double peaks. The longitudinal anti-correlation between the gravity waves' (GWs') potential energies and occurrence frequencies of double-layer PMCs suggests that the double-layer PMCs tend to form in an environment where the GWs have weaker intensities.

  15. Multi-Frequency Observations of Polar Mesospheric Summer Echoes (PMSE) Under Artificial Electron Heating at EISCAT

    NASA Astrophysics Data System (ADS)

    La Hoz, C.; Kosch, M.; Senior, A.; Pinedo, H.; Havnes, O.; Rietveld, M. T.; Häggström, I.

    2011-12-01

    In a unique experiment at EISCAT, located in northern Norway and executed in July 2011, Polar Mesospheric Summer Echoes (PMSE) have been observed in the zenith at four different radar frequencies (933, 224, 56 and 7.9 MHz) simultaneously whilst artificially heating the electrons with high-frequency radio waves. Increasing the electron temperature reduces PMSE backscatter power at VHF but may increase it at HF, while the opposite may happen during the relaxation period following heater off. The PMSE backscatter power depends on many parameters, including dust size and charge, radar frequency and electron temperature. By observing the artificially modified PMSE at multiple radar frequencies, it may be possible to uniquely determine dust parameters as a function of altitude. Validation of PMSE theories and its behaviour under electron heating employing this unique set of observations are underway. In addition, high aspect angle observations of the PMSE were obtained at 224 MHz with 66 degrees zenith angle. These clearly show that PMSE can be observed at very high aspect angle, at least for VHF, contrary to results from earlier attempts to investigate PMSE's aspect sensitivity behaviour that has a bearing on the geometry of the electron density irregularities that cause the scattering. Preliminary results from the campaign are presented.

  16. First SuperDARN polar mesosphere summer echoes observed at SANAE IV, Antarctica

    NASA Astrophysics Data System (ADS)

    Ogunjobi, Olakunle; Sivakumar, Venkataraman; Judy; Stephenson, A. E.

    For over 3 decades studies on Polar mesosphere summer echo (PMSE) is ongoing. Its causative mechanism in the Antarctic and Arctic mesopause altitude is yet to be completely understood and is partly due to few observations from Antarctica. Also important were the varied influencing factors across the observable locations. For the first time, we report the PMSE occurrence probability rates over South African National Antarctic Expedition IV (SANAE IV). A comparison is made with observation from SANAE IV magnetic conjugate vicinity, Goose Bay in Arctic region. Here, a new matching coincidence method allowing filtration of possible contaminating echoes is described and implemented for extraction of PMSE during the 2005-2007 summers. In this method, Riometer and Super Dual Auroral Radar Network (SuperDARN) measurements from SANAE IV location are matched to obtain PMSE occurrence probability rate. Whereas the seasonal and diurnal variations followed the known features of PMSE, the percentage difference in probability occurrence rate is found to be remarkable. The SANAE IV probability rate is found to be high for the summer months reaching about 50% peak around the summer solstice. When the coincidence algorithm is relaxed, we found a substantial 30% increase in PMSE occurrence rate at SANAE IV. At this time, about 100% peak is found for Goose Bay. The contribution from the ionospheric D region electron density enhancements to SuperDARN PMSE occurrence rates at locations under auroral regions will be presented.

  17. Patches of polar mesospheric summer echoes characterized from radar imaging observations with MAARSY

    NASA Astrophysics Data System (ADS)

    Sommer, Svenja; Chau, Jorge L.

    2016-12-01

    A recent study has hypothesized that polar mesospheric summer echoes (PMSEs) might consist mainly of localized isotropic scattering. These results have been inferred from indirect measurements. Using radar imaging with the Middle Atmosphere Alomar Radar System (MAARSY), we observed horizontal structures that support our previous findings. We observe that small-scale irregularities, causing isotropic scattering, are organized in patches. We find that patches of PMSEs, as observed by the radar, are usually smaller than 1 km. These patches occur throughout the illuminated volume, supporting that PMSEs are caused by localized isotropic or inhomogeneous scattering. Furthermore, we show that imaging can be used to identify side lobe detections, which have a significant influence even for narrow beam observations. Improved spectra estimations are obtained by selecting the desired volume to study parameters such as spectral width and to estimate the derived energy dissipation rates. In addition, a combined wide beam experiment and radar imaging is used to resolve the radial velocity and spectral width at different volumes within the illuminated volume.

  18. On the necessary complexity of modeling of the Polar Mesosphere Summer Echo Overshoot Effect

    NASA Astrophysics Data System (ADS)

    Biebricher, Alexander; Havnes, Ove; Bast, Radovan

    2012-06-01

    Recent numerical studies of the Polar Mesosphere Summer Echo (PMSE) Overshoot Effect predict the basic shape of the Overshoot Characteristic Curve (OCC) to undergo dramatic changes as the frequency of the radar decreases. Principally, this may render earlier modeling, which assumed near-instantaneous diffusion of electrons and ions, moot and exacerbate algebraic analysis of OCC obtained in the future with, e.g. the MORRO-radar (56 MHz) and a synchronized radio wave emitter, both at or near the European Incoherent Scatter (EISCAT) Scientific Association's site in Ramfjordmoen near Tromsø, Norway. Since, however, by far the most observational results on the PMSE Overshoot Effect have been assembled with the help of the Very High Frequency (VHF, 224 MHz) radar and the an Ultra High Frequency (UHF, 929 MHz) radar, both at the EISCAT site, we examine more closely whether near-instantaneous diffusion is a valid assumption for these particular frequencies. We show that, indeed, the earlier less complex and analytically more accessible model can still be considered sufficient for most, if not all, existing experimental data.

  19. Wave influence on polar mesosphere summer echoes above Wasa: experimental and model studies

    NASA Astrophysics Data System (ADS)

    Dalin, P.; Kirkwood, S.; Hervig, M.; Mihalikova, M.; Mikhaylova, D.; Wolf, I.; Osepian, A.

    2012-08-01

    Comprehensive analysis of the wave activity in the Antarctic summer mesopause is performed using polar mesospheric summer echoes (PMSE) measurements for December 2010-January 2011. The 2-day planetary wave is a statistically significant periodic oscillation in the power spectrum density of PMSE power. The strongest periodic oscillation in the power spectrum belongs to the diurnal solar tide; the semi-diurnal solar tide is found to be a highly significant harmonic oscillation as well. The inertial-gravity waves are extensively studied by means of PMSE power and wind components. The strongest gravity waves are observed at periods of about 1, 1.4, 2.5 and 4 h, with characteristic horizontal wavelengths of 28, 36, 157 and 252 km, respectively. The gravity waves propagate approximately in the west-east direction over Wasa (Antarctica). A detailed comparison between theoretical and experimental volume reflectivity of PMSE, measured at Wasa, is made. It is demonstrated that a new expression for PMSE reflectivity derived by Varney et al. (2011) is able to adequately describe PMSE profiles both in the magnitude and in height variations. The best agreement, within 30%, is achieved when mean values of neutral atmospheric parameters are utilized. The largest contribution to the formation and variability of the PMSE layer is explained by the ice number density and its height gradient, followed by wave-induced perturbations in buoyancy period and the turbulent energy dissipation rate.

  20. Geometric considerations of polar mesospheric summer echoes in tilted beams using coherent radar imaging

    NASA Astrophysics Data System (ADS)

    Sommer, S.; Stober, G.; Chau, J. L.; Latteck, R.

    2014-11-01

    We present observations of polar mesospheric summer echoes (PMSE) using the Middle Atmosphere Alomar Radar System in Northern Norway (69.30° N, 16.04° E). The radar is able to resolve PMSE at high spatial and temporal resolution and to perform pulse-to-pulse beam steering. In this experiment, 81 oblique beam directions were used with off-zenith angles up to 25°. For each beam pointing direction and range gate, coherent radar imaging was applied to determine the mean backscatter location. The location of the mean scatterer in the beam volume was calculated by the deviation from the nominal off-zenith angle of the brightest pixel. It shows that in tilted beams with an off-zenith angle greater than 5°, structures appear at the altitudinal edges of the PMSE layer. Our results indicate that the mean influence of the location of the maximum depends on the tilt of the beam and on the observed area of the PMSE layer. At the upper/lower edge of the PMSE layer, the mean backscatter has a greater/smaller off-zenith angle than the nominal off-zenith angle. This effect intensifies with greater off-zenith beam pointing direction, so the beam filling factor plays an important role in the observation of PMSE layers for oblique beams.

  1. Multi-frequency observations of Polar Mesospheric Summer Echoes and their aspect sensitivity at EISCAT

    NASA Astrophysics Data System (ADS)

    La Hoz, Cesar; Rietveld, Michael; Havnes, Ove; Senior, Andrew; Haggstrom, Ingemar; Kosch, Michael; Pinedo, Henry

    2012-07-01

    In a unique experiment at EISCAT in northern Norway, executed in July 2011, Polar Mesospheric Summer Echoes (PMSE) have been observed in the zenith at four different radar frequencies (933, 224, 56 and 7.9 MHz) simultaneously whilst artificially heating the electrons with high-frequency radio waves. In addition, measurements of the scattering layers were also made for the first time by the EISCAT_3D demonstrator array at 224 MHz located in Kiruna, Sweden, which is 234 km away from the transmitting site and obtains measurements at an aspect angle of 69 degrees. Strong scattering was observed over prolonged periods on several days by the demonstrator array. These measurements are at variance with previous aspect angle measurements that have reported aspect angles no greater than about 15 degrees. These results indicate that the turbulent irregularities that produce the scattering have a high degree of isotropy, which is more in line with Kolmogorov'a hypothesis of a universal scaling of turbulence based precisely on the assumption of homogeneity and isotropy in the inertial regime of turbulence which applies also, naturally, to the Batchelor regime due to large Schmidt numbers which is believed to be the case for PMSE. An interseting question arises, namely, what is the mechanism or process that controls the level of isotropy of the turbulent irregularities in the small scale regime, i.e., inertial or Batchelor, that the radars detect?

  2. Bright polar mesospheric clouds formed by main engine exhaust from the space shuttle's final launch

    NASA Astrophysics Data System (ADS)

    Stevens, Michael H.; Lossow, Stefan; Fiedler, Jens; Baumgarten, Gerd; Lübken, Franz-Josef; Hallgren, Kristofer; Hartogh, Paul; Randall, Cora E.; Lumpe, Jerry; Bailey, Scott M.; Niciejewski, R.; Meier, R. R.; Plane, John M. C.; Kochenash, Andrew J.; Murtagh, Donal P.; Englert, Christoph R.

    2012-10-01

    The space shuttle launched for the last time on 8 July 2011. As with most shuttle launches, the three main engines injected about 350 t of water vapor between 100 and 115 km off the east coast of the United States during its ascent to orbit. We follow the motion of this exhaust with a variety of satellite and ground-based data sets and find that (1) the shuttle water vapor plume spread out horizontally in all directions over a distance of 3000 to 4000 km in 18 h, (2) a portion of the plume reached northern Europe in 21 h to form polar mesospheric clouds (PMCs) that are brighter than over 99% of all PMCs observed in that region, and (3) the observed altitude dependence of the particle size is reversed with larger particles above smaller particles. We use a one-dimensional cloud formation model initialized with predictions of a plume diffusion model to simulate the unusually bright PMCs. We find that eddy mixing can move the plume water vapor down to the mesopause near 90 km where ice particles can form. If the eddy diffusion coefficient is 400 to 1000 m2/s, the predicted integrated cloud brightness is in agreement with both satellite and ground-based observations of the shuttle PMCs. The propellant mass of the shuttle is about 20% of that from all vehicles launched during the northern 2011 PMC season. We suggest that the brightest PMC population near 70°N is formed by space traffic exhaust.

  3. Seasonal Variation of turbulent Energy Dissipation Rates in the Polar Mesosphere

    NASA Astrophysics Data System (ADS)

    Singer, W.; Latteck, R.; Becker, E.

    Turbulent energy dissipation rates have been derived from the width of the observed signal spectra obtained with a narrow beam Doppler radar operated at 3 17 MHz in Andenes 69 r N using a computationally intensive correction method to remove contributions from non-turbulent processes Vertical and oblique beams with a minimum half-power full-beam width of 6 6 r are used The radar provides estimates of turbulent energy dissipation rates in an altitude range from 50 to about 90 km with a time resolution of 1 h and a range resolution of 1 km since September 2003 Turbulent energy dissipation rates based on radar observations vary in the order of 2-10 mW kg around 70 km and between about 10 and 200 mW kg around 85 km in dependence on season During the occurrence of strong polar mesosphere winter echoes in January 2005 energy dissipation rates between 30 and about 100 mW kg are observed at altitudes from 55 to 65 km The radar estimates of turbulent energy dissipation rates are in reasonable agreement with climatologically winter and summer data from previous rocket soundings at Andenes as well as with time-resolved results 1-h resolution from the Kuehlungsborn Mechanistic General Circulation Model KMCM model for summer and winter conditions

  4. Tomographic retrieval of water vapour and temperature around polar mesospheric clouds using Odin-SMR

    NASA Astrophysics Data System (ADS)

    Christensen, O. M.; Eriksson, P.; Urban, J.; Murtagh, D.; Hultgren, K.; Gumbel, J.

    2014-11-01

    A special observation mode of the Odin satellite provides the first simultaneous measurements of water vapour, temperature and polar mesospheric cloud (PMC) brightness over a large geographical area while still resolving both horizontal and vertical structures in the clouds and background atmosphere. The observation mode has been activated during June, July and August of 2010, 2011 and 2014, and for latitudes between 50 and 82° N. This paper focuses on the water vapour and temperature measurements carried out with Odin's sub-millimetre radiometer (SMR). The tomographic retrieval approach used provides water vapour and temperature between 75-90 km with a vertical resolution of about 2.5 km and a horizontal resolution of about 200 km. The precision of the measurements is estimated to 0.5 ppm for water vapour and 3 K for temperature. Due to limited information about the pressure at the measured altitudes, the results have large uncertainties (> 3 ppm) in the retrieved water vapour. These errors, however, influence mainly the mean atmosphere retrieved for each orbit, and variations around this mean are still reliably captured by the measurements. SMR measurements are performed using two different mixer chains, denoted as frequency mode 19 and 13. Systematic differences between the two frontends have been noted. A first comparison with the Solar Occultation For Ice Experiment instrument (SOFIE) on-board the Aeronomy of Ice in the Mesosphere (AIM) satellite and the Fourier Transform Spectrometer of the Atmospheric Chemistry Experiment (ACE-FTS) on-board SCISAT indicates that the measurements using the frequency mode 19 have a significant low bias in both temperature (> 20 K) and water vapour (> 1 ppm), while the measurements using frequency mode 13 agree with the other instruments considering estimated errors. PMC brightness data are provided by the OSIRIS, Odin's other sensor. Combined SMR and OSIRIS data for some example orbits are considered. For these orbits

  5. Tomographic retrieval of water vapour and temperature around polar mesospheric clouds using Odin-SMR

    NASA Astrophysics Data System (ADS)

    Christensen, O. M.; Eriksson, P.; Urban, J.; Murtagh, D.; Hultgren, K.; Gumbel, J.

    2015-05-01

    A special observation mode of the Odin satellite provides the first simultaneous measurements of water vapour, temperature and polar mesospheric cloud (PMC) brightness over a large geographical area while still resolving both horizontal and vertical structures in the clouds and background atmosphere. The observation mode was activated during June, July and August of 2010 and 2011, and for latitudes between 50 and 82° N. This paper focuses on the water vapour and temperature measurements carried out with Odin's sub-millimetre radiometer (SMR). The tomographic retrieval approach used provides water vapour and temperature between 75 and 90 km with a vertical resolution of about 2.5 km and a horizontal resolution of about 200 km. The precision of the measurements is estimated to 0.2 ppmv for water vapour and 2 K for temperature. Due to limited information about the pressure at the measured altitudes, the results have large uncertainties (> 3 ppmv) in the retrieved water vapour. These errors, however, influence mainly the mean atmosphere retrieved for each orbit, and variations around this mean are still reliably captured by the measurements. SMR measurements are performed using two different mixer chains, denoted as frequency mode 19 and 13. Systematic differences between the two frontends have been noted. A first comparison with the Solar Occultation For Ice Experiment instrument (SOFIE) on-board the Aeronomy of Ice in the Mesosphere (AIM) satellite and the Fourier Transform Spectrometer of the Atmospheric Chemistry Experiment (ACE-FTS) on-board SCISAT indicates that the measurements using the frequency mode 19 have a significant low bias in both temperature (> 15 K) and water vapour (> 0.5 ppmv), while the measurements using frequency mode 13 agree with the other instruments considering estimated errors. PMC brightness data is provided by OSIRIS, Odin's other sensor. Combined SMR and OSIRIS data for some example orbits is considered. For these orbits, effects of

  6. Occurrence frequencies of polar mesosphere summer echoes observed at 69° N during a full solar cycle

    NASA Astrophysics Data System (ADS)

    Latteck, R.; Bremer, J.

    2013-07-01

    Polar mesosphere summer echoes (PMSE) are strong enhancements of received signal power at very high radar frequencies occurring at altitudes between about 80 and 95 km at polar latitudes during summer. PMSE are caused by inhomogeneities in the electron density of the radar Bragg scale within the plasma of the cold summer mesopause region in the presence of negatively charged ice particles. Thus the occurrence of PMSE contains information about mesospheric temperature and water vapour content but also depends on the ionisation due to solar wave radiation and precipitating high energetic particles. Continuous and homogeneous observations of PMSE have been done on the North-Norwegian island Andøya (69.3° N, 16.0° E) from 1999 until 2008 using the ALWIN VHF radar at 53.5 MHz. In 2009 the Leibniz-Institute of Atmospheric Physics in Kühlungsborn, Germany (IAP) started the installation of the Middle Atmosphere Alomar Radar System (MAARSY) at the same location. The observation of mesospheric echoes could be continued in spring 2010 starting with an initial stage of expansion of MAARSY and is carried out with the completed installation of the radar since May 2011. Since both the ALWIN radar and MAARSY are calibrated, the received echo strength of PMSE from 14 yr of mesospheric observations could be converted to absolute signal power. Occurrence frequencies based on different common thresholds of PMSE echo strength were used for investigations of the solar and geomagnetic control of the PMSE as well as of possible long-term changes. The PMSE are positively correlated with the solar Lyman α radiation and the geomagnetic activity. The occurrence frequencies of the PMSE show slightly positive trends but with marginal significance levels.

  7. Studies of polar mesosphere summer echoes at multiple sites using calibrated radars

    NASA Astrophysics Data System (ADS)

    Swarnalingam, Nimalan

    A 51.5 MHz VHF radar system, located at Resolute Bay in northern Canada has been monitoring Polar Mesosphere Summer Echoes (PMSE) since 1997. This is currently the northernmost radar used to monitor PMSE in the North American sector. It has been recording a lower level of PMSE activity in this region, compared with the PMSE activity recorded by other high latitudes radars operating at similar frequencies. To investigate the reason for this, the radar system has been absolutely calibrated by means of cosmic sky noise variations along with the help of a calibrated noise source. A general theory is developed in such a way that the calibration procedure can be directly applied to any MST radar system anywhere in the world, provided the sky noise variations are known. PMSE backscatter cross-sections for the Resolute Bay radar are estimated, converted into an equivalent electron density structure function constant, C2N , and compared with three other radars located at Yellowknife and Andenes during simultaneous measurements. It was found that the estimated C2N for Resolute Bay is at least an order of magnitude lower than the estimated values at the other two locations. This leads us to conclude that the reason why PMSE strengths at Resolute Bay are weak compared with other sites is geophysical in origin, and not due to instrumental effects. The seasonal and diurnal variations of PMSE at Resolute Bay, and their connection to cold mesopause temperatures, are investigated on a long term basis, and compared with the observations at Andenes on a short term basis. Although the PMSE season is relatively short at Resolute Bay, the PMSE temporal variation pattern agrees with Andenes for at least one season. On the other hand, the two sites show a completely different picture for diurnal variations. While PMSE at Andenes show a clear diurnal variation, PMSE at Resolute Bay are modulated by high frequency oscillations. For the first time, a group of near identical SKiYMET meteor

  8. Polar and apolar active matter

    NASA Astrophysics Data System (ADS)

    Marchetti, M. Cristina

    2008-03-01

    Assemblies of interacting self-driven units form a new type of active soft matter with collective behavior qualitatively different from that of its individual constituents, nonequilibrium phase transitions, and unusual mechanical and rheological properties. Examples include cytoskeletal filaments crosslinked by motor proteins, bacterial colonies, migrating cells, and vibrated layers of granular rods. In this talk I will review our work on using nonequilibrium statistical physics to derive a continuum description of these systems from specific models of single particle dynamics. This approach aims at understanding the interplay between physical mechanisms (such as formation or loss of physical connections, excluded volume effects, directional forces) and biochemical or other processes in regulating the large-scale organization and function of active matter. I will contrast the behavior of units with a head and a tail that can exhibit a macroscopic polar state, where all organisms move coherently in a preferred direction, with that of units with head-tail symmetry, that can order in a nematic state, with no net motion on macroscopic scale. Finally, I will use a simple model of active rods on a substrate to discuss the interplay between equilibrium steric effects and self-propulsion in controlling order and fluctuations in active fluids.

  9. Improvement of OMI ozone profile retrievals by simultaneously fitting polar mesospheric clouds

    NASA Astrophysics Data System (ADS)

    Bak, Juseon; Liu, Xiong; Kim, Jae H.; Deland, Matthew T.; Chance, Kelly

    2016-09-01

    The presence of polar mesospheric clouds (PMCs) at summer high latitudes could affect the retrieval of ozone profiles using backscattered ultraviolet (UV) measurements. PMC-induced errors in ozone profile retrievals from Ozone Monitoring Instrument (OMI) backscattered UV measurements are investigated through comparisons with Microwave Limb Sounder (MLS) ozone measurements. This comparison demonstrates that the presence of PMCs leads to systematic biases for pressures smaller than 6 hPa; the biases increase from ˜ -2 % at 2 hPa to ˜ -20 % at 0.5 hPa on average and are significantly correlated with brightness of PMCs. Sensitivity studies show that the radiance sensitivity to PMCs strongly depends on wavelength, increasing by a factor of ˜ 4 from 300 to 265 nm. It also strongly depends on the PMC scattering, thus depending on viewing geometry. The optimal estimation-based retrieval sensitivity analysis shows that PMCs located at 80-85 km have the greatest effect on ozone retrievals at ˜ 0.2 hPa ( ˜ 60 km), where the retrieval errors range from -2.5 % with PMC vertical optical depth (POD) of 10-4 to -20 % with 10-3 POD at backscattering angles. The impacts increase by a factor of ˜ 5 at forward-scattering angles due to stronger PMC sensitivities. To reduce the interference of PMCs on ozone retrievals, we perform simultaneous retrievals of POD and ozone with a loose constraint of 10-3 for POD, which results in retrieval errors of 1-4 × 10-4. It is demonstrated that the negative bias of OMI ozone retrievals relative to MLS can be improved by including the PMC in the forward-model calculation and retrieval.

  10. Simultaneous Retrievals of Polar Mesospheric Clouds (PMCs) with Ozone from OMI UV measurements

    NASA Astrophysics Data System (ADS)

    Bak, J.; Liu, X.; Kim, J. H.; Deland, M. T.; Chance, K.

    2015-09-01

    The presence of polar mesospheric clouds (PMCs) at high latitudes could affect the retrieval of ozone profiles using backscattered ultraviolet (BUV) measurements. PMC-induced errors in ozone profile retrievals from Ozone Monitoring Instrument (OMI) BUV measurements are investigated through comparisons with Microwave Limb Sounder (MLS) ozone measurements. This comparison demonstrates that the presence of PMCs leads to systematic biases at altitudes above 6 hPa in summer high latitudes; the biases increase from ~ -2 % at 2 hPa to ~ -20 % at 0.5 hPa on average, and are significantly correlated with brightness of PMCs. Sensitivity studies show that the radiance sensitivity to PMCs strongly depends on wavelengths, increasing by a factor of ~ 4 from 300 to 265 nm. It also strongly depends on the PMC scattering, thus depending on viewing geometry. The optimal estimation-based retrieval sensitivity analysis shows that PMCs located at 80-85 km have the greatest effect on ozone retrievals at ~ 0.2 hPa (~ 60 km), where the retrieval errors range from -2.5 % with PMC optical depth (POD) of 10-4 to -20 % with 10-3 at back scattering angles, and the impacts increase by a factor of ~ 5 at forward scattering angles due to stronger PMC sensitivities. To reduce the interference of PMCs on ozone retrievals, we perform simultaneous retrievals of POD and ozone with a loose constraint of 10-3 for POD, which results in retrieval errors of 1-4 × 10-4. It is demonstrated that the negative bias of OMI ozone retrievals relative to MLS could be improved by including the PMC in the forward model calculation and retrieval.

  11. Measurements of global distributions of polar mesospheric clouds during 2005-2012 by MIPAS/Envisat

    NASA Astrophysics Data System (ADS)

    García-Comas, Maya; López-Puertas, Manuel; Funke, Bernd; Aythami Jurado-Navarro, Á.; Gardini, Angela; Stiller, Gabriele P.; von Clarmann, Thomas; Höpfner, Michael

    2016-06-01

    We have analysed MIPAS (Michelson Interferometer for Passive Atmopheric Sounding) infrared measurements of PMCs for the summer seasons in the Northern (NH) and Southern (SH) hemispheres from 2005 to 2012. Measurements of PMCs using this technique are very useful because they are sensitive to the total ice volume and independent of particle size. For the first time, MIPAS has provided coverage of the PMC total ice volume from midlatitudes to the poles. MIPAS measurements indicate the existence of a continuous layer of mesospheric ice, extending from about ˜ 81 km up to about 88-89 km on average and from the poles to about 50-60° in each hemisphere, increasing in concentration with proximity to the poles. We have found that the ice concentration is larger in the Northern Hemisphere than in the Southern Hemisphere. The ratio between the ice water content (IWC) in both hemispheres is also latitude-dependent, varying from a NH / SH ratio of 1.4 close to the poles to a factor of 2.1 around 60°. This also implies that PMCs extend to lower latitudes in the NH. A very clear feature of the MIPAS observations is that PMCs tend to be at higher altitudes with increasing distance from the polar region (in both hemispheres), particularly equatorwards of 70°, and that they are about 1 km higher in the SH than in the NH. The difference between the mean altitude of the PMC layer and the mesopause altitude increases towards the poles and is larger in the NH than in the SH. The PMC layers are denser and wider when the frost-point temperature occurs at lower altitudes. The layered water vapour structure caused by sequestration and sublimation of PMCs is present at latitudes northwards of 70° N and more pronounced towards the pole. Finally, MIPAS observations have also shown a clear impact of the migrating diurnal tide on the diurnal variation of the PMC volume ice density.

  12. Light in condensed matter in the upper atmosphere as the origin of homochirality: circularly polarized light from Rydberg matter.

    PubMed

    Holmlid, Leif

    2009-01-01

    Clouds of the condensed excited Rydberg matter (RM) exist in the atmospheres of comets and planetary bodies (most easily observed at Mercury and the Moon), where they surround the entire bodies. Vast such clouds are recently proposed to exist in the upper atmosphere of Earth (giving rise to the enormous features called noctilucent clouds, polar mesospheric clouds, and polar mesospheric summer radar echoes). It has been shown in experiments with RM that linearly polarized visible light scattered from an RM layer is transformed to circularly polarized light with a probability of approximately 50%. The circular Rydberg electrons in the magnetic field in the RM may be chiral scatterers. The magnetic and anisotropic RM medium acts as a circular polarizer probably by delaying one of the perpendicular components of the light wave. The delay process involved is called Rabi-flopping and gives delays of the order of femtoseconds. This strong effect thus gives intense circularly polarized visible and UV light within RM clouds. Amino acids and other chiral molecules will experience a strong interaction with this light field in the upper atmospheres of planets. The interaction will vary with the stereogenic conformation of the molecules and in all probability promote the survival of one enantiomer. Here, this strong effect is proposed to be the origin of homochirality. The formation of amino acids in the RM clouds is probably facilitated by the catalytic effect of RM.

  13. High-speed solar wind streams and polar mesosphere winter echoes at Troll, Antarctica

    NASA Astrophysics Data System (ADS)

    Kirkwood, S.; Osepian, A.; Belova, E.; Lee, Y.-S.

    2015-06-01

    A small, 54 MHz wind-profiler radar, MARA, was operated at Troll, Antarctica (72° S, 2.5° E), continuously from November 2011 to January 2014, covering two complete Antarctic winters. Despite very low power, MARA observed echoes from heights of 55-80 km (polar mesosphere winter echoes, PMWE) on 60% of all winter days (from March to October). This contrasts with previous reports from radars at high northern latitudes, where PWME have been reported only by very high power radars or during rare periods of unusually high electron density at PMWE heights, such as during solar proton events. Analysis shows that PWME at Troll were not related to solar proton events but were often closely related to the arrival of high-speed solar wind streams (HSS) at the Earth, with PWME appearing at heights as low as 56 km and persisting for up to 15 days following HSS arrival. This demonstrates that HSS effects penetrate directly to below 60 km height in the polar atmosphere. Using local observations of cosmic-noise absorption (CNA), a theoretical ionization/ion-chemistry model and a statistical model of precipitating energetic electrons associated with HSS, the electron density conditions during the HSS events are estimated. We find that PMWE detectability cannot be explained by these variations in electron density and molecular-ion chemistry alone. PWME become detectable at different thresholds depending on solar illumination and height. In darkness, PWME are detected only when the modelled electron density is above a threshold of about 1000 cm-3, and only above 75 km height, where negative ions are few. In daylight, the electron density threshold falls by at least 2 orders of magnitude and PWME are found primarily below 75 km height, even in conditions when a large proportion of negative ions is expected. There is also a strong dawn-dusk asymmetry with PWME detected very rarely during morning twilight but often during evening twilight. This behaviour cannot be explained if PMWE

  14. Remote Sensing of PMCs with the Polar Suborbital Science in the Upper Mesosphere (PoSSUM) Lidar

    NASA Astrophysics Data System (ADS)

    Mitchell, S.; Thayer, J. P.; Reimuller, J. D.

    2013-12-01

    The Polar Suborbital Science in the Upper Mesosphere (PoSSUM) experiment is a modular observatory readily integrated into commercial manned Reusable Suborbital Launch Vehicles (RSLV) for aeronomy, remote sensing, solar physics, astronomy/astrophysics, and Earth observations. The proposed observatory, scheduled for deployment in July 2015, is being designed to operate onboard the XCOR Lynx and Virgin Galactic SpaceShipTwo vehicles. The observatory will enable unprecedented capabilities to dedicate low-cost suborbital campaigns for the study of the small-scale dynamics of polar mesospheric clouds (PMC) by obtaining imagery and remotely sensed data from apogee altitudes in excess of 100 km. A key component of the observatory is the PoSSUM Lidar, a Rayleigh/Mie backscatter lidar currently being designed at the University of Colorado at Boulder. The proposed instrument transmitter consists of a 532 nm linearly polarized laser coupled with conditioning and steering optics. The receiver employs a photon counting approach to detect the received optical signals backscattered from PMCs during flight operations. The design of the PoSSUM Lidar will be presented, including the unique challenges associated with developing a lidar instrument for operations onboard a RSLV. Initial simulation data will be explored, including a discussion of the expected science products output by the lidar, such as PMC height and density, as well as the potential for depolarization measurements to evaluate PMC asphericity.

  15. Near-simultaneous Observations of Polar Mesospheric Clouds from the International Space Station and from Orbiting Optical Instruments

    NASA Astrophysics Data System (ADS)

    Pettit, D.; Rusch, D. W.; Thomas, G. E.; Merkel, A.; Bailey, S. M.; Russell, J. M.; Deland, M.

    2004-12-01

    The orbit of the International Space Station (ISS) carried the spacecraft to latitudes high enough for observations of Polar Mesospheric Clouds (PMC). During the PMC southern-hemisphere season 2002-2003, a series of digital images and visual observations were taken over the Antarctic continent of PMC at the sunlit limb. Approximately twenty such observations, available through the ISS LAB window towards the summer pole, revealed the PMC as a distinct narrow scattering layer in the upper mesosphere, often many thousands of kilometers in horizontal expanse. The field of view from the ISS covered a sufficiently wide area of the polar region, that it was possible to co-locate measurements taken by instruments on board unmanned spacecraft in the near vicinity of the Space Station (but taken from a higher altitude). This provided an opportunity to combine accurate limb scans and nadir views of PMC with high-resolution information on the horizontal spatial structure. The SNOE and NOAA-16 and NOAA-17 SBUV/2 instruments obtained 15 orbits per day of PMC measurements at UV wavelengths. In addition, the SABER experiment on board the TIMED satellite obtained temperature profiles in the same vicinity. We will report on the first comparisons of these data, and describe the specific advantages of this unique combination of data.

  16. Studies of stratospheric and mesospheric chemistry in polar regions with the Berlin Climate Middle Atmosphere Model (CMAM CHEM)

    NASA Astrophysics Data System (ADS)

    Grenfell, J. L.; Mieth, P.; Kruger, K.; Langematz, U.; Labitzke, K.; Steil, B.

    2001-12-01

    The Berlin Climate Middle Atmosphere model (CMAM) with resolution T21 and lid at 84km (Langematz and Pawson, 1997) has been interactively coupled with the chemistry module of Steil et al., (1998). Chemical tracer fields from a test run which used the Palmer gravity wave drag (GWD) scheme have been found to compare well both with observations and other models (e.g. MA-ECHAM4-CHEM). However, in this run the model pole has a warm bias and dynamical variability is not well reproduced. Therefore we are currently testing a suite of orographic and non-orographic GWD schemes in the model. Preliminary results from these latter runs are presented here and focus on stratospheric and mesospheric chemical processes during polar winter, particularly those affecting ozone. The contrast between hemispheres, the springtime 'recovery' of polar stratospheric ozone and relevant chemical diurnal cycles are explored. Bibliography U. Langematz, and Pawson S., The Berlin troposphere-stratosphere-mesosphere GCM: Climatology and forcing mechanisms, Q. J. R. Meteorol. Soc., 123, 1075-1096, 1997 B. Steil, Dameris M., Brühl C., Crutzen P. J., Grewe V., Ponater M., and Sausen R., Development of a chemistry module for GCMs: first results of a multiannual integration, Ann. Geophys., 16, 205-228, 1998

  17. Multi-radar observations of polar mesosphere summer echoes during the PHOCUS campaign on 20-22 July 2011

    NASA Astrophysics Data System (ADS)

    Belova, E.; Kirkwood, S.; Latteck, R.; Zecha, M.; Pinedo, H.; Hedin, J.; Gumbel, J.

    2014-10-01

    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.

  18. Preliminary Study on Active Modulation of Polar Mesosphere Summer Echoes with the Radio Propagation in Layered Space Dusty Plasma

    NASA Astrophysics Data System (ADS)

    Zhou, Shengguo; Li, Hailong; Fu, Luyao; Wang, Maoyan

    2016-06-01

    Radar echoes intensity of polar mesosphere summer echoes (PMSE) is greatly affected by the temperature of dusty plasma and the frequency of electromagnetic wave about the radar. In this paper, a new method is developed to explain the active experiment results of PMSE. The theory of wave propagation in a layered media is used to study the propagation characteristics of an electromagnetic wave at different electron temperatures. The simulation results show that the variation tendency of the reflected power fraction almost agrees with the results observed by radar in the European Incoherent Scatter Scientific Association (EISCAT). The radar echoes intensity of PMSE greatly decreases with the increase of the radio frequency and the enhancement of the electron temperature. supported by National Natural Science Foundation of China (Nos. 41104097 and 41304119) and by the National Key Laboratory of Electromagnetic Environment, China Research Institute of Radiowave Propagation (CRIRP)

  19. Rocket observations of positive ions during polar mesosphere winter echo conditions at Andenes in January 2005; first analysis and interpretations

    NASA Astrophysics Data System (ADS)

    Brattli, A.; Rapp, M.; Singer, W.; Lattek, R.; Friedrich, M.; Havnes, O.; Blix, T. A.; Svenes, K. R.

    2005-08-01

    On Janurary 18, 2005, two instrumented miniaturised rocket payloads, each with a Positive Ion Probe (PIP) and a Faraday rotation/differential absorption experiment, were launched from Andøya Rocket Range (69°N). The instrumented payloads were launched into conditions with Polar Mesosphere Winter Echoes (PMWE) as part of a salvo of meteorological rockets measuring temperature and wind using falling spheres and chaff. Layers of PMWE were detected in the altitude range 55-77 km by the 53.5 MHz ALWIN radar. Fluctuations in the ion density, as measured in situ by the instrumented payloads, show that there was turbulence inside the PMWE layers, but not above/below and between. Data from the PIPs are analysed and related to the geophysical conditions, as observed with the ALWIN radar and meteorological rockets.

  20. Seasonal transitions and possible polar mesospheric cloud regions calculated by a zonally averaged model of the middle atmosphere

    NASA Astrophysics Data System (ADS)

    Memmesheimer, M.; Gaertner, V.; Blum, P. W.

    1986-12-01

    A global, zonally averaged dynamical model of the middle atmosphere is used to calculate the seasonal variations of winds and temperature from 10 to 110 km. The main purpose of the study is to search for the existence of regions where noctilucent or polar mesospheric clouds (NLC/PMC) may be formed. For this purpose the difference between the actual temperature and the frost point is calculated based on a fixed water vapor mixing ratio. A value of 10 ppmV is chosen, which is in the upper range of the data obtained by different measurement techniques. Possible cloud existence regions (PCR) are defined by the condition that the actual temperature is below the frost point inside the PCR. It is found that this is the case for the summer polar mesopause during May-August (in the northern hemisphere) and November-February (in the southern hemisphere). The PCR extends from the pole to approximately 60° latitude at a height of about 85 km. In addition, in the lower stratosphere during winter the temperature also falls below the frost point, approximately at an altitude where stratospheric clouds are observed. The time-dependent behaviour of the PCR is investigated and compared with the data of the ultraviolet spectrometer on board the SME satellite and with ground-based observations of noctilucent clouds. It can be shown that the time of the NLC/PMC season is in good agreement with the time span covered by the estimated possible cloud region. The fast changes in atmospheric circulation and temperatures at mesospheric heights during late spring/early summer and late summer/beginning of autumn are an interesting fact. This may be responsible for the sudden start/end of the cloud season. The study shows that two dimensional modeling may be a good approach to get more insight into the development of large-scale atmospheric background conditions necessary for PMC/NLC formation.

  1. Laboratory studies of VUV photochemistry of water ice: measurements of photodesorption rates and implication for Polar Mesospheric Clouds

    NASA Astrophysics Data System (ADS)

    Kulikov, Mikhail; Feigin, Alexander; Ignatov, Stanislav; Sennikov, Petr; Schrems, Otto

    Polar Mesospheric Clouds (PMC) are the highest clouds of the Earth's atmosphere. They are formed during summer at middle to high latitudes in an altitude range between 80 and 90 km when the air temperature drops below 150K. The particles of PMC consist primarily of ice [1] and are formed as a result of water vapor condensation. In the day time, PMC are subjected to strong solar Lyman -α irradiation with the wavelength of 121.6 nm which penetrates into ice particles and is absorbed essentially. This leads to photodissociation of H2 O molecules and to formation of mobile and chemically active components in the solid phase. As a result, a whole spectrum of physicochemical processes can be initiated inside the particles: diffusion of primary products, chemical formation of secondary products, accumulation of both type of products in the ice matrix and their escaping into gas-phase. Murray and Plane [2] hypothesized that the last process is dominant, i.e. each Lyman -α photon absorbed by a particle of PMC results in the ejection of one H atom and one OH radical into gas phase that provides essential enhancement of HOx concentration with a corresponding increase in Ox removal. Nevertheless, they justly pointed to the need of laboratory measurements of the H and OH yield from ice under conditions pertinent to the summer mesosphere. We have carried out first laboratory studies of water ice photochemistry to acquiring knowledge about physicochemical processes inside particles of PMC initiated by solar irradiation. The experimental set-up used includes a high-vacuum chamber, a gas-inlet system, a refrigerator-cryostat with temperature controller, a FTIR spectrometer, a vacuum ultraviolet hydrogen lamp and a microwave generator. This work presents results of measurements of the absolute photodesorption rate (loss of substance due to the escape of photoproducts into gas phase) from thin (20-100nm) water ice samples at temperatures of 120-150 K. The data obtained demonstrate

  2. Aspect sensitivity of polar mesosphere summer echoes based on ESRAD MST radar measurements in Kiruna, Sweden in 1997-2010

    NASA Astrophysics Data System (ADS)

    Smirnova, M.; Belova, E.; Kirkwood, S.

    2012-03-01

    Aspect sensitivities of polar mesosphere summer echoes (PMSE) measured with the ESRAD 50 MHz radar in 1997-2010 are studied using the full correlation analysis technique. Half of PMSE detected each year are found to be highly aspect sensitive. Yearly median values of the aspect sensitivity parameter θs, characterising the half-width of the scatterers' polar diagram, are 2.9-3.7° depending on the year. The other half of the PMSE have θs values larger than 9-11° and cannot be evaluated using the ESRAD vertical beam only. PMSE aspect sensitivity reveals an altitude dependence, namely, the scatter becomes more isotropic with increasing height. This result is consistent with that reported in other studies. No dependence of PMSE aspect sensitivity on backscattered power for any year was identified. In the paper the limitations of the in-beam and off-vertical beam methods for estimation of PMSE aspect sensitivity are discussed. We conclude that both methods should be combined in order to get complete information about PMSE aspect sensitivity and to estimate correctly PMSE absolute strength.

  3. Imaging of Polar Mesosphere Summer Echoes with the 450 MHz Poker Flat Advanced Modular Incoherent Scatter Radar

    NASA Astrophysics Data System (ADS)

    Nicolls, M. J.; Heinselman, C. J.; Hope, E. A.; Ranjan, S.; Kelley, M. C.; Kelly, J. D.

    2007-10-01

    Polar Mesosphere Summer Echoes (PMSE) occur near the mesopause during the polar summer months. PMSE are primarily studied at VHF, however there have been some detections at higher frequencies. Here, we report on some of the first detections of PMSE with the 450 MHz (67 cm) Poker Flat Advanced Modular Incoherent Scatter Radar (PFISR). Echoes were observed with volume reflectivities (radar scattering cross section per unit volume) near 2-3 × 10-17 m-1. On 11 June 2007, PFISR was operating in a 26-beam position mode, with look directions spread over an approximately 80 by 80 km2 region at 85 km altitude with elevation angles as low as ~50°. The measurements showed patchy (tens of kilometer) irregularity regions drifting in from the north, in addition to smaller, more localized structures. There was no evidence for strong aspect sensitivity of these UHF echoes, as PMSE was observed in all look directions with relatively uniform intensity. The observations indicate the presence of fossilized irregularities drifting with the background wind field as well as areas of developing irregularities possibly associated with the presence of active neutral air turbulence.

  4. Observation of Polar Mesosphere Summer Echoes using the northernmost MST radar at Eureka (80°N)

    NASA Astrophysics Data System (ADS)

    Swarnalingam, N.; Hocking, W.; Janches, D.; Drummond, J.

    2017-09-01

    We investigate long-term Polar Mesosphere Summer Echoes (PMSEs) observations conducted by the northernmost geographically located MST radar at Eureka (80°N, 86°W). While PMSEs are a well recognized summer phenomenon in the polar regions, previous calibrated studies at Resolute Bay and Eureka using 51.5 MHz and 33 MHz radars respectively, showed that PMSE backscatter signal strengths are relatively weak in the polar cap sites, compared to the auroral zone sites (Swarnalingam et al., 2009b; Singer et al., 2010). Complications arise with PMSEs in which the echo strength is controlled by the electrons, which are, in turn, influenced by heavily charged ice particles as well as the variability in the D-region plasma. In recent years, PMSE experiments were conducted inside the polar cap utilizing a 51 MHz radar located at Eureka. In this paper, we investigate calibrated observations, conducted during 2009-2015. Seasonal and diurnal variations of the backscatter signal strengths are discussed and compared to previously published results from the ALOMAR radar, which is a radar of similar design located in the auroral zone at Andenes, Norway (69°N, 16°E). At Eureka, while PMSEs are present with a daily occurrence rate which is comparable to the rate observed at the auroral zone site for at least two seasons, they show a great level of inter-annual variability. The occurrence rate for the strong echoes tends to be low. Furthermore, comparison of the absolute backscatter signal strengths at these two sites clearly indicates that the PMSE backscatter signal strength at Eureka is weak. Although this difference could be caused by several factors, we investigate the intensity of the neutral air turbulence at Eureka from the measurements of the Doppler spectrum of the PMSE backscatter signals. We found that the level of the turbulence intensity at Eureka is weak relative to previously reported results from three high latitude sites.

  5. Polar mesosphere summer echoes observed with the EISCAT 933-MHz radar and the CUPRI 46.9-MHz radar, their similarity to 224-MHz radar echoes, and their relation to turbulence and electron density profiles

    NASA Astrophysics Data System (ADS)

    Roettger, J.; Rietveld, M. T.; La Hoz, C.; Hall, T.; Kelley, M. C.

    1990-08-01

    The relation of the coherent echoes from the mesosphere detected by an incoherent scatter UHF radar to the echoes registered simultaneously with a portable radar interferometer is analyzed. It is demonstrated that these 933-MHz echoes are of the same character as the VHF radar polar mesosphere summer echoes. It is also noted that a narrow electron density observed in the incoherent scatter UHF radar data occurs at the comparable altitude as the portable radar interferometer polar mesosphere summer echoes (PMSE). Potential origins of the scattering process of the PMSEs observed in VHF and UHF are discussed, with focus placed on enhanced electron density fluctuations as well as steep electron density gradients in the presence of cluster ions in the cold polar mesosphere.

  6. Super Soaker: A Sounding Rocket Mission to Study Transport, Chemistry, and Energetics of Water in the Mesosphere and Lower Thermosphere and Implications for Polar Mesospheric Cloud Occurrence

    NASA Astrophysics Data System (ADS)

    Azeem, S. I.; Collins, R. L.; Larsen, M. F.; Stevens, M. H.; Taylor, M. J.

    2016-12-01

    Water deposition in the Mesosphere and Lower Thermosphere (MLT) from space traffic can lead to significant variations in the composition and dynamics of the region. Stevens et al., 2005 and Kelley et al., 2010, for example, showed that the fast global-scale plume transport from NASA's Space Shuttle launches can lead to the formation of PMCs. This is an important finding because PMCs have been implicated as possible indicators of long-term climate change [e.g. Thomas and Olivero, 2001 and references therein]. The water plume phenomenon raises a number of important questions about lower thermospheric and mesospheric processes, ranging from dynamics and chemistry to PMC formation and climatology. The Super Soaker rocket mission, funded by the NASA Heliophysics Technology and Instrument Development for Science (H-TIDes) program, seeks to investigate the time-dependent neutral chemistry and transport of water in the MLT and to determine the resultant impact on the local temperature and ice cloud formation. Super Soaker is tentatively scheduled for launch in April 2018 from the Poker Flat Rocket Range (PFRR), Alaska. The mission is designed to release a plume of water vapor from a rocket payload and observe how the atmosphere responds both during and after the release. The rocket experiment will be supported on the ground by lidar observations of temperature and PMCs, temperature maps using the Advanced Mesosphere Temperature Mapper (AMTM), ground-based wind observations using TMA releases, PFISR observations of electron density, and data from the NASA AIM and TIMED satellites. In this paper we review the Super Soaker rocket mission and describe initial numerical modeling results to provide a semi-quantitative view of the response of chemistry and energetic to the water plume deposition in the lower thermosphere.

  7. Polar mesosphere summer echoes at Wasa, Antarctica (73°S): First observations and comparison with 68°N

    NASA Astrophysics Data System (ADS)

    Kirkwood, S.; Wolf, I.; Nilsson, H.; Dalin, P.; Mikhaylova, D.; Belova, E.

    2007-08-01

    Polar mesosphere summer echoes (PMSE) have been observed for the first time at Wasa, Antarctica (73°S, 13°W, 61° geomagnetic). A new 54.5 MHz radar, MARA, operated first in Kiruna (68°N) during late summer 2006 and then at Wasa between 18 January and 5 February 2007. Operation in Kiruna allowed accurate cross calibration with the permanent 52 MHz radar ESRAD. PMSE at 73°S are found to have very similar characteristics to PMSE at 68°N. When observations from the same part of the summer season are compared, volume reflectivities show very similar distributions over different intensities, over height and over local-time. PMSE at 68°N (65° geomagnetic) are stronger in the midnight sector, likely due to the different geomagnetic latitudes. Above 85 km altitude, weak PMSE have a higher occurrence rate at 73°S. The height of peak PMSE occurrence is ~1 km higher at 73°S compared to 68°N.

  8. Solar-induced 27-day variations of polar mesospheric clouds from the AIM SOFIE and CIPS experiments

    NASA Astrophysics Data System (ADS)

    Thurairajah, Brentha; Thomas, Gary E.; von Savigny, Christian; Snow, Martin; Hervig, Mark E.; Bailey, Scott M.; Randall, Cora E.

    2017-09-01

    Polar Mesospheric Cloud (PMC) observations from the Solar Occultation for Ice Experiment (SOFIE) and the Cloud Imaging and Particle Size (CIPS) experiment are used to investigate the response of PMCs to forcing associated with the 27-day solar rotation. We quantify the PMC response in terms of sensitivity values. Analysis of PMC data from 14 seasons indicate a large seasonal variability in sensitivity with both correlation and anti-correlation between PMC properties and Lyman-alpha irradiance for individual seasons. However, a superposed epoch analysis reveals the expected anti-correlation between variations in solar Lyman-alpha and variations in PMC ice water content, albedo, and frequency of occurrence. The PMC height is found to significantly correlate with 27-day variations in solar Lyman-alpha in the Southern Hemisphere (SH), but not in the Northern hemisphere (NH). Depending on instrument and property, the time lag between variations in PMC properties and solar Lyman-alpha ranges from 0 to 3 days in the NH and from 6 to 7 days in the SH. These hemispheric differences in PMC height and time lag are not understood, but it is speculated that they result from dynamical forcing that is controlled by the 27-day solar cycle.

  9. Evidence for two different structuring and scattering mechanisms and the associated role of aerosols in the polar summer mesosphere

    NASA Technical Reports Server (NTRS)

    Ulwick, J. C.; Kelley, M. C.; Alcala, C.; Blix, T. A.; Thrane, E. V.

    1993-01-01

    A Super Arcas rocket, MISTI B, was launched as part of the Polar Mesospheric Summer Echoes (PMSE) salvo to measure electron density irregularities using rf and dc probes. Large and small scale structures in the electron density were measured on rocket ascent and descent at the altitudes of 86.5 and 88.5 +/- .5 km. Since the rocket apogee was 89 km, the rocket was in the height range 88.5 +/- .5 km for 30 seconds giving us an unusual measurement of horizontal structure over a distance of 5.5 km. A power spectrum of the fluctuations for the upper layer gives further evidence that turbulent mixing is an important process in PMSE. The power spectrum of the lower layer, however, gives evidence that this layer is characterized by a form of partial or Fresnel scattering. Both spectra are in excellent agreement with similar analysis of electron fluctuation spectra measured in the same layers on the TURBO-B rocket flown 12 minutes later and the analysis of Cornell University Portable Radar Interferometer (CUPRI) data by Cho et al., 1993A. Thus two different structuring and scattering mechanisms exist at altitudes only 1 km apart. Using the simultaneous dc and rf probe measurements of electron depletions and sharp gradients in the lower layer, we speculate on the role of aerosols in creating these depletions and gradients.

  10. A statistical study of the polar mesosphere summer echoes overshoot effect with EISCAT VHF during the present solar cycle

    NASA Astrophysics Data System (ADS)

    Pinedo, H.; La Hoz, C.; Havnes, O.; Rietveld, M. T.

    2013-12-01

    We have conducted observational campaigns using EISCAT radars and the heater to modify the strength of the polar mesosphere summer echoes (PMSE). In 2003, Havnes et al. predicted and measured a PMSE overshoot effect. The overshoot effect was strong and frequently observed in the next years following its discovery, but afterwards it has become weaker and rarely observed. However, it seems that this effect has reappeared in our most recent summer campaign in 2013. We will show a statistical study of the occurrence and strength of the heating and the overshoot effect based on observations around the PMSE peak season in the years 2003-2013, this corresponds to approximately a solar cycle. It is know that a major factor controlling the electron heating at the PMSE layer is the electron density below it. It is plausible that the electron density has been unfavorable in the case when the PMSE overshoot was absent. The aim of this study is to verify if the occurrence of the PMSE overshoot and heating effects are correlated with changes in the electron density as determined by the phase of the solar cycle. However, we cannot exclude that other factors are at play.

  11. Observation of polar mesosphere summer echoes with calibrated VHF radars at 69° in the Northern and Southern hemispheres

    NASA Astrophysics Data System (ADS)

    Latteck, R.; Singer, W.; Morris, R. J.; Holdsworth, D. A.; Murphy, D. J.

    2007-07-01

    Polar Mesosphere Summer Echoes (PMSE) observed in the northern and southern hemisphere were studied using continuous measurements obtained by calibrated VHF radars located at Andenes (69.3°N) and Davis (68.6°S) during the boreal summer 2004 and the austral summer 2004/2005. The PMSE observed at Davis have a lower peak volume reflectivity of approximately 4 . 10-11 m-1 compared with their counterparts (7 . 10-10 m-1) observed at Andenes. The duration of the PMSE season is correlated with the dynamical and thermal state of the mesopause region supported by recent studies using meridional winds and temperatures. PMSE occurred less frequently but with greater variability above Davis. The diurnal variation of PMSE occurrence has a maximum around 11-16 LT in both hemispheres, and a minimum occurs during late evening with a longer duration in the southern hemisphere. The mean PMSE season at both sites started around 34 days before solstice, but the duration of the Davis PMSE season is about 9 days shorter than at Andenes. The maximum occurrence height of PMSE at Davis is 86 km which is about 1 km higher than at Andenes.

  12. Evidence for two different structuring and scattering mechanisms and the associated role of aerosols in the polar summer mesosphere

    NASA Astrophysics Data System (ADS)

    Ulwick, J. C.; Kelley, M. C.; Alcala, C.; Blix, T. A.; Thrane, E. V.

    1993-10-01

    A Super Arcas rocket, MISTI B, was launched as part of the Polar Mesospheric Summer Echoes (PMSE) salvo to measure electron density irregularities using rf and dc probes. Large and small scale structures in the electron density were measured on rocket ascent and descent at the altitudes of 86.5 and 88.5 +/- .5 km. Since the rocket apogee was 89 km, the rocket was in the height range 88.5 +/- .5 km for 30 seconds giving us an unusual measurement of horizontal structure over a distance of 5.5 km. A power spectrum of the fluctuations for the upper layer gives further evidence that turbulent mixing is an important process in PMSE. The power spectrum of the lower layer, however, gives evidence that this layer is characterized by a form of partial or Fresnel scattering. Both spectra are in excellent agreement with similar analysis of electron fluctuation spectra measured in the same layers on the TURBO-B rocket flown 12 minutes later and the analysis of Cornell University Portable Radar Interferometer (CUPRI) data by Cho et al., 1993A. Thus two different structuring and scattering mechanisms exist at altitudes only 1 km apart. Using the simultaneous dc and rf probe measurements of electron depletions and sharp gradients in the lower layer, we speculate on the role of aerosols in creating these depletions and gradients.

  13. Comparing nadir and limb observations of polar mesospheric clouds: The effect of the assumed particle size distribution

    NASA Astrophysics Data System (ADS)

    Bailey, Scott M.; Thomas, Gary E.; Hervig, Mark E.; Lumpe, Jerry D.; Randall, Cora E.; Carstens, Justin N.; Thurairajah, Brentha; Rusch, David W.; Russell, James M.; Gordley, Larry L.

    2015-05-01

    Nadir viewing observations of Polar Mesospheric Clouds (PMCs) from the Cloud Imaging and Particle Size (CIPS) instrument on the Aeronomy of Ice in the Mesosphere (AIM) spacecraft are compared to Common Volume (CV), limb-viewing observations by the Solar Occultation For Ice Experiment (SOFIE) also on AIM. CIPS makes multiple observations of PMC-scattered UV sunlight from a given location at a variety of geometries and uses the variation of the radiance with scattering angle to determine a cloud albedo, particle size distribution, and Ice Water Content (IWC). SOFIE uses IR solar occultation in 16 channels (0.3-5 μm) to obtain altitude profiles of ice properties including the particle size distribution and IWC in addition to temperature, water vapor abundance, and other environmental parameters. CIPS and SOFIE made CV observations from 2007 to 2009. In order to compare the CV observations from the two instruments, SOFIE observations are used to predict the mean PMC properties observed by CIPS. Initial agreement is poor with SOFIE predicting particle size distributions with systematically smaller mean radii and a factor of two more albedo and IWC than observed by CIPS. We show that significantly improved agreement is obtained if the PMC ice is assumed to contain 0.5% meteoric smoke by mass, in agreement with previous studies. We show that the comparison is further improved if an adjustment is made in the CIPS data processing regarding the removal of Rayleigh scattered sunlight below the clouds. This change has an effect on the CV PMC, but is negligible for most of the observed clouds outside the CV. Finally, we examine the role of the assumed shape of the ice particle size distribution. Both experiments nominally assume the shape is Gaussian with a width parameter roughly half of the mean radius. We analyze modeled ice particle distributions and show that, for the column integrated ice distribution, Log-normal and Exponential distributions better represent the range

  14. Polar mesosphere summer echoes (PMSE) studied at Bragg wavelengths of 2.8 m, 67 cm, and 16 cm

    NASA Astrophysics Data System (ADS)

    Rapp, Markus; Strelnikova, Irina; Latteck, Ralph; Hoffmann, Peter; Hoppe, Ulf-Peter; Häggström, Ingemar; Rietveld, Michael T.

    2008-05-01

    We present observations of radar volume reflectivities under conditions of polar mesosphere summer echoes (PMSE) at three frequencies, i.e., 53.5, 224, and 930 MHz corresponding to Bragg wavelengths of 2.8, 0.67, and 0.16 m. These measurements were made with the ALWIN radar in Andenes and the EISCAT VHF and UHF radars in Tromsø. Contributions to the signal at 930 MHz by incoherent scatter are used to estimate electron number densities and their gradient at PMSE altitudes, and spectral width measurements of Doppler spectra recorded at 224 MHz are used to estimate the turbulent energy dissipation rate. We further derive a theoretical expression for the radar volume reflectivity for the case of turbulent scatter aided by a large Schmidt number (i.e., the current standard theory of PMSE) and show that our observations quantitatively agree with this theory if Schmidt numbers between 2500 and 5000 are assumed. We then show that these Schmidt numbers correspond to ice particles with radii in the range 20-30 nm which should frequently occur in the polar summer mesopause region. In addition, we show that for the short period when PMSE was observed at UHF frequencies the volume reflectivity is proportional to a factor determined by the turbulent energy dissipation rate, electron number density, and the electron number density gradient in agreement with theory. We consider our findings as strong support that PMSE at all considered frequencies is indeed created by turbulent scatter in the presence of a large Schmidt number. We finally highlight that ultimate proof of this concept will require the direct measurement of ice particle sizes in a PMSE environment probed by radars covering frequencies between 50 MHz and 1 GHz.

  15. Studying the Inter-Hemispheric Coupling During Polar Summer Mesosphere Warming in 2002

    NASA Technical Reports Server (NTRS)

    Goldberg, Richard A.; Feofilov, Artem; Pesnell, William; Kutepov, Alexander A.

    2010-01-01

    It has been found that the northern summer polar mesopause region in 2002 was warmer than normal and of shorter duration than for other years analyzed. Theoretical studies have implied that the abnormal characteristics of this polar summer were generated by unusual dynamical processes occurring in the southern polar winter hemisphere. We have used data from the SABER instrument aboard the NASA TIMED Satellite to study these processes for polar summer periods of 2002-2009. For background, SABER is a broadband limb scanning radiometer that measures a large number of minor atmospheric constituents as well as pressure and temperature in the 13-110 km altitude range over most of the globe.We will use SABER temperature data to illustrate the correlated heating seen between the southern and northern hemispheres during June and July 2002. We will then describe the approach to study the wave characteristics of the atmospheric temperature profiles and demonstrate the features that were unique for 2002 compared to the other years.

  16. Studying the Inter-Hemispheric Coupling During Polar Summer Mesosphere Warming in 2002

    NASA Technical Reports Server (NTRS)

    Goldberg, Richard A.; Feofilov, Artem; Pesnell, William; Kutepov, Alexander A.

    2010-01-01

    It has been found that the northern summer polar mesopause region in 2002 was warmer than normal and of shorter duration than for other years analyzed. Theoretical studies have implied that the abnormal characteristics of this polar summer were generated by unusual dynamical processes occurring in the southern polar winter hemisphere. We have used data from the SABER instrument aboard the NASA TIMED Satellite to study these processes for polar summer periods of 2002-2009. For background, SABER is a broadband limb scanning radiometer that measures a large number of minor atmospheric constituents as well as pressure and temperature in the 13-110 km altitude range over most of the globe.We will use SABER temperature data to illustrate the correlated heating seen between the southern and northern hemispheres during June and July 2002. We will then describe the approach to study the wave characteristics of the atmospheric temperature profiles and demonstrate the features that were unique for 2002 compared to the other years.

  17. The relationship between polar mesospheric clouds and their background atmosphere as observed by Odin-SMR and Odin-OSIRIS

    NASA Astrophysics Data System (ADS)

    Christensen, Ole Martin; Benze, Susanne; Eriksson, Patrick; Gumbel, Jörg; Megner, Linda; Murtagh, Donal P.

    2016-10-01

    In this study the properties of polar mesospheric clouds (PMCs) and the background atmosphere in which they exist are studied using measurements from two instruments, OSIRIS and SMR, on board the Odin satellite. The data comes from a set of tomographic measurements conducted by the satellite during 2010 and 2011. The expected ice mass density and cloud frequency for conditions of thermodynamic equilibrium, calculated using the temperature and water vapour as measured by SMR, are compared to the ice mass density and cloud frequency as measured by OSIRIS. We find that assuming thermodynamic equilibrium reproduces the seasonal, latitudinal and vertical variations in ice mass density and cloud frequency, but with a high bias of a factor of 2 in ice mass density. To investigate this bias, we use a simple ice particle growth model to estimate the time it would take for the observed clouds to sublimate completely and the time it takes for these clouds to reform. We find a difference in the median sublimation time (1.8 h) and the reformation time (3.2 h) at peak cloud altitudes (82-84 km). This difference implies that temperature variations on these timescales have a tendency to reduce the ice content of the clouds, possibly explaining the high bias of the equilibrium model. Finally, we detect and are, for the first time, able to positively identify cloud features with horizontal scales of 100 to 300 km extending far below the region of supersaturation ( > 2 km). Using the growth model, we conclude these features cannot be explained by sedimentation alone and suggest that these events may be an indication of strong vertical transport.

  18. Small-scale structure of O2(+) and proton hydrates in a Noctilucent Cloud and polar mesospheric summer echo of August 9/10 1991 above Kiruna

    NASA Technical Reports Server (NTRS)

    Balsiger, F.; Kopp, E.; Friedrich, M.; Torkar, K. M.; Walchli, U.

    1993-01-01

    A novel mass spectrometer designed to measure simultaneously positive ion composition in the mesosphere, was successfully launched during the NLC-91 project. Instruments supporting the mass spectrometer were a probed to measure both electrons and positive ions as well as a wave propagation experiment. The location of the Noctilucent Clouds (NLC) was determined by a particle impact sensor to detect secondary electrons and ions from the impact of NLC particle. The density of proton hydrates and of the related total ions is depleted in the NLC region at 83 km. An improved detection limit of 5 x 10(exp 4)/cu m for positive ions and improved height resolution revealed for the first time large gradients in the O2(+), H(+)(H2O)2 and H(+)(H2O)6 densities within a small height range of the order of 50 m. Such gradients at the altitude of NLC and Polar Mesospheric Summer Echoes (PMSE) are associated with strong variability of mesospheric water vapor, temperature and neutral air density.

  19. Seasonal variations of the Na and Fe layers at the South Pole and their implications for the chemistry and general circulation of the polar mesosphere

    NASA Astrophysics Data System (ADS)

    Gardner, Chester S.; Plane, John M. C.; Pan, Weilin; Vondrak, Tomas; Murray, Benjamin J.; Chu, Xinzhao

    2005-05-01

    Lidar observations, conducted at the South Pole by University of Illinois researchers, are used to characterize the seasonal variations of mesospheric Na and Fe above the site. The annual mean layer abundances are virtually identical to midlatitude values, and the mean centroid height is just 100 m higher for Na and 450 m higher for Fe compared with 40°N. The most striking feature of the metal profiles is the almost complete absence of Na and Fe below 90 km during midsummer. This leads to summertime layers with significantly higher peaks, narrower widths, and smaller abundances than are observed at lower latitudes. The measurements are compared with detailed chemical models of these species that were developed at the University of East Anglia. The models accurately reproduce most features of these observations and demonstrate the importance of rapid uptake of the metallic species on the surfaces of polar mesospheric clouds and meteoric smoke particles. The models show that vertical downwelling in winter, associated with the meridional circulation system, must be less than about 1 cm s-1 in the upper mesosphere in order to avoid displacing the minor constituents O, H, and the metal layers too far below 85 km. They also show that an additional source of gas-phase metallic species, that is comparable to the meteoric input, is required during winter to correctly model the Na and Fe abundances. This source appears to arise from the wintertime convergence of the meridional flow over the South Pole.

  20. Small-scale structure of O2(+) and proton hydrates in a Noctilucent Cloud and polar mesospheric summer echo of August 9/10 1991 above Kiruna

    NASA Technical Reports Server (NTRS)

    Balsiger, F.; Kopp, E.; Friedrich, M.; Torkar, K. M.; Walchli, U.

    1993-01-01

    A novel mass spectrometer designed to measure simultaneously positive ion composition in the mesosphere, was successfully launched during the NLC-91 project. Instruments supporting the mass spectrometer were a probed to measure both electrons and positive ions as well as a wave propagation experiment. The location of the Noctilucent Clouds (NLC) was determined by a particle impact sensor to detect secondary electrons and ions from the impact of NLC particle. The density of proton hydrates and of the related total ions is depleted in the NLC region at 83 km. An improved detection limit of 5 x 10(exp 4)/cu m for positive ions and improved height resolution revealed for the first time large gradients in the O2(+), H(+)(H2O)2 and H(+)(H2O)6 densities within a small height range of the order of 50 m. Such gradients at the altitude of NLC and Polar Mesospheric Summer Echoes (PMSE) are associated with strong variability of mesospheric water vapor, temperature and neutral air density.

  1. Quantification of the SF6 lifetime based on mesospheric loss measured in the stratospheric polar vortex

    NASA Astrophysics Data System (ADS)

    Ray, Eric A.; Moore, Fred L.; Elkins, James W.; Rosenlof, Karen H.; Laube, Johannes C.; Röckmann, Thomas; Marsh, Daniel R.; Andrews, Arlyn E.

    2017-04-01

    Sulfur hexafluoride (SF6) is a greenhouse gas with one of the highest radiative efficiencies in the atmosphere as well as an important indicator of transport time scales in the stratosphere. The current widely used estimate of the atmospheric lifetime of SF6 is 3200 years. In this study we use in situ measurements in the 2000 Arctic polar vortex that sampled air with up to 50% SF6 loss to calculate an SF6 lifetime. Comparison of these measurements with output from the Whole Atmosphere Community Climate Model (WACCM) shows that WACCM transport into the vortex is accurate and that an important SF6 loss mechanism, believed to be electron attachment, is missing in the model. Based on the measurements and estimates of the size of the vortex, we calculate an SF6 lifetime of 850 years with an uncertainty range of 580-1400 years. The amount of SF6 loss is shown to be consistent with that of HFC-227ea, which has a lifetime of 670-780 years, adding independent support to our new SF6 lifetime estimate. Based on the revised lifetime the global warming potential of SF6 will decrease only slightly for short time horizons (<100 years) but will decrease substantially for time horizons longer than 2000 years. Also, the use of SF6 measurements as an indicator of transport time scales in the stratosphere clearly must account for potential influence from polar vortex air.

  2. Polar thermospheric Joule heating, and redistribution of recombination energy in the upper mesosphere

    NASA Technical Reports Server (NTRS)

    Mayr, H. G.; Harris, I.; Dube, M.

    1990-01-01

    Kellogg (1961), suggested that transport of atomic oxygen from the summer into the winter hemisphere and subsequent release of energy by three body recombination, O+O+N2 yields O2+N2+E, may contribute significantly to the so-called mesopause temperature anomaly. Earlier model calculations have shown that Kellogg's mechanism produces about a 10-percent increase in the temperature from summer to winter at 90 km. This process, however, is partly compensated by differential heating from absorption of UV radiation associated with dissociation of O2. In the auroral region of the thermosphere, there is a steady energy dissipation by Joule heating causing a redistribution and depletion of atomic oxygen due to wind-induced diffusion. With the removal of O, latent chemical energy normally released by three body recombination is also removed, and the result is that the temperature decreases by almost 2 percent near 90 km. Through dynamic feedback, this process reduces the depletion of atomic oxygen by about 25 percent and the temperature perturbation in the exosphere from 10 to 7 percent at polar latitudes. Under the influence of the internal dynamo interaction, the prevailing zonal circulation in the upper thermosphere changes direction when the redistribution of recombination energy is considered.

  3. Polar thermospheric Joule heating, and redistribution of recombination energy in the upper mesosphere

    NASA Technical Reports Server (NTRS)

    Mayr, H. G.; Harris, I.; Dube, M.

    1990-01-01

    Kellogg (1961), suggested that transport of atomic oxygen from the summer into the winter hemisphere and subsequent release of energy by three body recombination, O+O+N2 yields O2+N2+E, may contribute significantly to the so-called mesopause temperature anomaly. Earlier model calculations have shown that Kellogg's mechanism produces about a 10-percent increase in the temperature from summer to winter at 90 km. This process, however, is partly compensated by differential heating from absorption of UV radiation associated with dissociation of O2. In the auroral region of the thermosphere, there is a steady energy dissipation by Joule heating causing a redistribution and depletion of atomic oxygen due to wind-induced diffusion. With the removal of O, latent chemical energy normally released by three body recombination is also removed, and the result is that the temperature decreases by almost 2 percent near 90 km. Through dynamic feedback, this process reduces the depletion of atomic oxygen by about 25 percent and the temperature perturbation in the exosphere from 10 to 7 percent at polar latitudes. Under the influence of the internal dynamo interaction, the prevailing zonal circulation in the upper thermosphere changes direction when the redistribution of recombination energy is considered.

  4. A comparison of overshoot modelling with observations of polar mesospheric summer echoes at radar frequencies of 56 and 224 MHz

    NASA Astrophysics Data System (ADS)

    Havnes, O.; Pinedo, H.; La Hoz, C.; Senior, A.; Hartquist, T. W.; Rietveld, M. T.; Kosch, M. J.

    2015-06-01

    We have compared radar observations of polar mesospheric summer echoes (PMSEs) modulated by artificial electron heating, at frequencies of 224 MHz (EISCAT VHF) and 56 MHz (MORRO). We have concentrated on 1 day of observation, lasting ~ 3.8 h. The MORRO radar, with its much wider beam, observes one or more PMSE layers all the time while the VHF radar observes PMSEs in 69% of the time. Statistically there is a clear difference between how the MORRO and the VHF radar backscatter reacts to the heater cycling (48 s heater on and 168 s heater off). While MORRO often reacts by having its backscatter level increased when the heater is switched on, as predicted by Scales and Chen (2008), the VHF radar nearly always sees the "normal" VHF overshoot behaviour with an initial rapid reduction of backscatter. However, in some heater cycles we do see a substantial recovery of the VHF backscatter after its initial reduction to levels several times above that just before the heater was switched on. For the MORRO radar a recovery during the heater-on phase is much more common. The reaction when the heater was switched off was a clear overshoot for nearly all VHF cases but less so for MORRO. A comparison of individual curves for the backscatter values as a function of time shows, at least for this particular day, that in high layers above ~ 85 km height, both radars see a reduction of the backscatter as the heater is switched on, with little recovery during the heater-on time. These variations are well described by present models. On the other hand, the backscatter in low layers at 81-82 km can be quite different, with modest or no reduction in backscatter as the heater is switched on, followed by a strong recovery for both radars to levels several times above that of the undisturbed PMSEs. This simultaneous, nearly identical behaviour at the two very different radar frequencies is not well described by present modelling.

  5. Response of polar mesosphere summer echoes to geomagnetic disturbances in the Southern and Northern Hemispheres: the importance of nitric oxide

    NASA Astrophysics Data System (ADS)

    Kirkwood, S.; Belova, E.; Dalin, P.; Mihalikova, M.; Mikhaylova, D.; Murtagh, D.; Nilsson, H.; Satheesan, K.; Urban, J.; Wolf, I.

    2013-02-01

    The relationship between polar mesosphere summer echoes (PMSE) and geomagnetic disturbances (represented by magnetic K indices) is examined. Calibrated PMSE reflectivities for the period May 2006-February 2012 are used from two 52.0/54.5 MHz radars located in Arctic Sweden (68° N, geomagnetic latitude 65°) and at two different sites in Queen Maud Land, Antarctica (73°/72° S, geomagnetic latitudes 62°/63°). In both the Northern Hemisphere (NH) and the Southern Hemisphere (SH) there is a strong increase in mean PMSE reflectivity between quiet and disturbed geomagnetic conditions. Mean volume reflectivities are slightly lower at the SH locations compared to the NH, but the position of the peak in the lognormal distribution of PMSE reflectivities is close to the same at both NH and SH locations, and varies only slightly with magnetic disturbance level. Differences between the sites, and between geomagnetic disturbance levels, are primarily due to differences in the high-reflectivity tail of the distribution. PMSE occurrence rates are essentially the same at both NH and SH locations during most of the PMSE season when a sufficiently low detection threshold is used so that the peak in the lognormal distribution is included. When the local-time dependence of the PMSE response to geomagnetic disturbance level is considered, the response in the NH is found to be immediate at most local times, but delayed by several hours in the afternoon sector and absent in the early evening. At the SH sites, at lower magnetic latitude, there is a delayed response (by several hours) at almost all local times. At the NH (auroral zone) site, the dependence on magnetic disturbance is highest during evening-to-morning hours. At the SH (sub-auroral) sites the response to magnetic disturbance is weaker but persists throughout the day. While the immediate response to magnetic activity can be qualitatively explained by changes in electron density resulting from energetic particle

  6. Polarization of photons emitted by decaying dark matter

    NASA Astrophysics Data System (ADS)

    Bonivento, W.; Gorbunov, D.; Shaposhnikov, M.; Tokareva, A.

    2017-02-01

    Radiatively decaying dark matter may be searched through investigating the photon spectrum of galaxies and galaxy clusters. We explore whether the properties of dark matter can be constrained through the study of a polarization state of emitted photons. Starting from the basic principles of quantum mechanics we show that the models of symmetric dark matter are indiscernible by the photon polarization. However, we find that the asymmetric dark matter consisted of Dirac fermions is a source of circularly polarized photons, calling for the experimental determination of the photon state.

  7. Source for the traveling planetary waves in the polar winter mesosphere and lower thermosphere: vertical coupling versus in-situ instability.

    NASA Astrophysics Data System (ADS)

    Lu, X.; Chen, C.; Chu, X.; Nguyen, V.; Smith, A. K.

    2016-12-01

    In the polar winter stratosphere, a group of eastward propagating planetary waves (relative to ground) are generated by the instability of the polar vortex and dominate the variability of chemistry and dynamics of the atmosphere. The strong polar vortex consisting of strong eastward winds support the propagation of these planetary waves until they reach the critical filtering level in the upper stratosphere. However, lidar measurements at McMurdo (78S), Antarctica illustrate the significant signatures of the planetary waves up to 110 km, making it intriguring to identify the wave source. The SD-WACCM well reproduces both local and global structure of these planeaty waves as compared with the ground-based lidar and satellite (MLS), which is thus used to derive the EP flux induced by these planetary waves. In addition to a region of positive EP flux divergence in the stratosphere where we expect to have the stratospheric planetary waves generated, a localized EP flux divergence is also found in the mesosphere and lower thermosphere (MLT) at high latitudes, which likely triggers the generation the waves locally or amplifies those waves that survive from the critical level filtering. By incorporating the background winds from SD-WACCM, a stand-alone mechanistic model with gravity wave effect parameterized is applied to investigate the relative importance of the vertical propagation and in-situ instability to the generation of the planetary waves in the mesosphere and lower thermosphere and whether and how there two processes are coupled together. The gravity wave effect on planetary waves is also addressed. This study provides insights on the vertical wave coupling via wave-wave and wave-mean interactions in the polar winter region.

  8. Large ice particles associated with small ice water content observed by AIM CIPS imagery of polar mesospheric clouds: Evidence for microphysical coupling with small-scale dynamics

    NASA Astrophysics Data System (ADS)

    Rusch, D.; Thomas, G.; Merkel, A.; Olivero, J.; Chandran, A.; Lumpe, J.; Carstans, J.; Randall, C.; Bailey, S.; Russell, J.

    2017-09-01

    Observations by the Cloud Imaging and Particle Size (CIPS) instrument on the Aeronomy of Ice in the Mesosphere (AIM) satellite have demonstrated the existence of Polar Mesospheric Cloud (PMC) regions populated by particles whose mean sizes range between 60 and 100 nm (radii of equivalent volume spheres). It is known from numerous satellite experiments that typical mean PMC particle sizes are of the order of 40-50 nm. Determination of particle size by CIPS is accomplished by measuring the scattering of solar radiation at various scattering angles at a spatial resolution of 25 km2. In this size range we find a robust anti-correlation between mean particle size and albedo. These very-large particle-low-ice (VLP-LI) clouds occur over spatially coherent areas. The surprising result is that VLP-LI are frequently present either in the troughs of gravity wave-like features or at the edges of PMC voids. We postulate that an association with gravity waves exists in the low-temperature summertime mesopause region, and illustrate the mechanism by a gravity wave simulation through use of the 2D Community Aerosol and Radiation Model for Atmospheres (CARMA). The model results are consistent with a VLP-LI population in the cold troughs of monochromatic gravity waves. In addition, we find such events in Whole Earth Community Climate Model/CARMA simulations, suggesting the possible importance of sporadic downward winds in heating the upper cloud regions. This newly-discovered association enhances our understanding of the interaction of ice microphysics with dynamical processes in the upper mesosphere.

  9. Fault system polarity: A matter of chance?

    NASA Astrophysics Data System (ADS)

    Schöpfer, Martin; Childs, Conrad; Manzocchi, Tom; Walsh, John; Nicol, Andy; Grasemann, Bernhard

    2015-04-01

    Many normal fault systems and, on a smaller scale, fracture boudinage exhibit asymmetry so that one fault dip direction dominates. The fraction of throw (or heave) accommodated by faults with the same dip direction in relation to the total fault system throw (or heave) is a quantitative measure of fault system asymmetry and termed 'polarity'. It is a common belief that the formation of domino and shear band boudinage with a monoclinic symmetry requires a component of layer parallel shearing, whereas torn boudins reflect coaxial flow. Moreover, domains of parallel faults are frequently used to infer the presence of a common décollement. Here we show, using Distinct Element Method (DEM) models in which rock is represented by an assemblage of bonded circular particles, that asymmetric fault systems can emerge under symmetric boundary conditions. The pre-requisite for the development of domains of parallel faults is however that the medium surrounding the brittle layer has a very low strength. We demonstrate that, if the 'competence' contrast between the brittle layer and the surrounding material ('jacket', or 'matrix') is high, the fault dip directions and hence fault system polarity can be explained using a random process. The results imply that domains of parallel faults are, for the conditions and properties used in our models, in fact a matter of chance. Our models suggest that domino and shear band boudinage can be an unreliable shear-sense indicator. Moreover, the presence of a décollement should not be inferred on the basis of a domain of parallel faults only.

  10. On the formation of sharp gradients in electron density resulting from an ice-plasma feedback instabilities in the polar summer mesosphere

    NASA Astrophysics Data System (ADS)

    Yee, J.; Bahcivan, H.

    2014-12-01

    Polar Mesospheric Summer Echoes (PMSEs) have commonly been attributed to scattering from (1) volume-filled electron density turbulence and (2) extremely sharp (meter-scale) gradients in electron density. In-situ sounding rockets have measured both extended regions of turbulence as well as electron density ledges. Unlike the turbulence theory, which has been extensively studied, a theory on the formation of sharp edges has yet to be explored. In this study, we reconsider the study of Gumbel et al. [2002] on the influences of ice particles on the ion chemistry and propose a theory of ice-plasma feedback instability in order to explain the origin of sharp electron density gradients. A one-dimensional particle-in-cell simulation of a multi-constituent weakly-ionized plasma has been developed to capture the physics of proton-hydrates (H+[H20]n), ice, and plasma interactions on a spatial grid of approximately 25 m. The simulation captures (1) the development of the proton-hydrate chain starting at n=4 via Thomson's model and Natanson's recombination scheme, (2) the formation of ice nucleation on large cluster proton-hydrates (n > 73), (3) the attachment of electrons (and ions) to ice particles, and resulting depletion of the plasma density, which significantly accelerates the proton-hydrate chain and ionic nucleation of new ice particles, (4) and the development of an ice-plasma feedback instability whereby the repeated process of developing new ice particles leads to capture of even more electrons and further depletion of existing regions of lower plasma density. Since this feedback instability process is faster than typical aerosol diffusion rates in this region, existing gradients steepen to produce electron density ledges. Although ionic nucleation is not feasible as the major mesospheric nucleation process, it can become efficient locally, near the coldest parts of the mesosphere because the proton-hydrate chain development is extremely sensitive to ambient

  11. Possible link of sudden onset and short-time periodic pulsation of polar mesosphere summer echoes to ULF Pc5 geomagnetic pulsations and solar wind dynamic pressure enhancement

    NASA Astrophysics Data System (ADS)

    Lee, Y.; Kirkwood, S.; Kwak, Y. S.

    2016-12-01

    The EISCAT VHF incoherent scatter radar in Tromsö, Norway, makes occasional observations of electron densities and Polar Mesosphere Summer Echoes, in the summer polar D-region ionosphere. In one of those datasets, pulsating polar mesospheric summer echoes (PMSE) are observed, with periodicities in the ultra-low frequency (ULF) Pc5 band (1.6-6.7 mHz), following an abrupt increase of the radar reflectivity when a geomagnetic field excursion is started, in turn linked to dynamic pressure (Pdyn) enhancement in the solar wind. At the excursion of the magnetic field, at auroral altitudes of 90 km and above, electron density is abruptly enhanced, followed by a series of short-lived peaks, superimposed on an enhanced level. The short-lived peaks are likely a signature of transient Pc5 geomagnetic pulsations and associated energetic electron precipitation from pitch-angle scattering into the loss cone in the magnetosphere. At the same time, at altitudes around 80-90 km, a sharp increase of PMSE reflectivity occurs, 100 times greater than the increase of electron density, and is followed by pulsating PMSE reflectivity with periodicities in the Pc5 band, increasing and decreasing in magnitude during the course of the next hour. The increase of the pulsation magnitude may be attributed to an increase of high-energy electron precipitation flux ( >30 keV) penetrating to at least the height of maximum PMSE reflectivity. This study suggests that Pc5 pulsation bursts in both magnetic field and high energy electron precipitation could play a crucial role in producing PMSE fluctuations on minute-to-minute time scales.

  12. Proof-of-Concept Study for Ground-based Millimetre-wave Observations of Horizontal Winds in the Polar Stratosphere and Mesosphere

    NASA Astrophysics Data System (ADS)

    Newnham, D.; Ford, G. P.; Moffat-Griffin, T.; Pumphrey, H. C.

    2015-12-01

    Detailed observations of horizontal winds in the Polar Regions are essential to understand chemical transport, atmospheric dynamics, waves and tides, and improve knowledge of polar and global climate systems. New measurement techniques for the altitude range 20-70 km are needed to address the current sparse wind observations for the upper stratosphere and mesosphere that limits our understanding of vertical wave propagation and its impact on planetary-scale circulation. We demonstrate the feasibility of remote sensing stratospheric and mesospheric zonal and meridional winds using ground-based passive millimetre wave spectroradiometry. Vertical profiles of horizontal winds are retrieved from simulations of line-of-sight Doppler-shifted atmospheric emission lines above Halley station (75°37'S, 26°14'W), Antarctica. Using the 231.28 GHz ozone line, or the pair of ozone lines at 249.79 GHz and 249.96 GHz, and a radiometer system temperature of 1400 K we estimate that daily mean wind profiles over the altitude range 25-75 km could be observed with a measurement uncertainty of 4-8 ms-1 and vertical resolution of 10-15 km. Under optimal observing conditions at Halley the temporal resolution is predicted to improve to 1-3 hrs, allowing studies of planetary and large-scale gravity waves. Combining observations of the 231.28 GHz ozone line and the 230.54 GHz carbon monoxide line extends the altitude coverage to ~95 km. The effects of clear-sky seasonal mean winter/summer conditions, zenith angle of the received atmospheric emission, and spectrometer frequency resolution on the altitude coverage, measurement uncertainty, and height and time resolution of the retrieved wind profiles have been determined.

  13. Does cell polarity matter during spermatogenesis?

    PubMed

    Gao, Ying; Cheng, C Yan

    2016-01-01

    Cell polarity is crucial to development since apico-basal polarity conferred by the 3 polarity protein modules (or complexes) is essential during embryogenesis, namely the Par (partition defective)-, the CRB (Crumbs)-, and the Scribble-based polarity protein modules. While these protein complexes and their component proteins have been extensively studied in Drosophila and C. elegans and also other mammalian tissues and/or cells, their presence and physiological significance in the testis remain unexplored until the first paper on the Par-based protein published in 2008. Since then, the Par-, the Scribble- and the CRB-based protein complexes and their component proteins in the testis have been studied. These proteins are known to confer Sertoli and spermatid polarity in the seminiferous epithelium, and they are also integrated components of the tight junction (TJ) and the basal ectoplasmic specialization (ES) at the Sertoli cell-cell interface near the basement membrane, which in turn constitute the blood-testis barrier (BTB). These proteins are also found at the apical ES at the Sertoli-spermatid interface. Thus, these polarity proteins also play a significant role in regulating Sertoli and spermatid adhesion in the testis through their actions on actin-based cytoskeletal function. Recent studies have shown that these polarity proteins are having antagonistic effects on the BTB integrity in which the Par6- and CRB3-based polarity complexes promotes the integrity of the Sertoli cell TJ-permeability barrier, whereas the Scribble-based complex promotes restructuring/remodeling of the Sertoli TJ-barrier function. Herein, we carefully evaluate these findings and provide a hypothetic model regarding their role in the testis in the context of the functions of these polarity proteins in other epithelia, so that better experiments can be designed in future studies to explore their significance in spermatogenesis.

  14. PERSPECTIVE: Snow matters in the polar regions

    NASA Astrophysics Data System (ADS)

    Sodeau, John

    2010-03-01

    to 30 times greater than those found in ice-free areas. The main question to ask is: how might the bromine have become released to the atmosphere? Many ideas have, in fact, been put forward over the last few years as to how such polar ocean-troposphere exchanges can take place. Much of the interest was driven by the so-called 'sudden' ozone depletion episodes first detected in Arctic air during the 1990s alongside simultaneous bromine 'explosions' which were monitored by ground-based instrumentation and satellite (as the radical BrO) over sea-ice covered by snowpack (Hausmann and Platt 1994, Schonhardt et al 2008). The likely precursors suggested, to date, have been sea-salt, frost-flowers and anthropogenic contents rather than organo- bromine matter (Simpson et al 2007). Associated processing routes including the formation of HOBr, the need for acidity, the involvement of trihalide ions and the potential role of freezing processes and the quasi-liquid layer have all been discussed in this context (Abbatt 1994, Neshyba et al 2009, O'Driscoll et al 2006). Computational work has also led to suggestions that preferential surface dispersion of the more highly polarizable halides (iodide and bromide ions) may lead to their direct interfacial reaction with atmospheric ozone leading to BrO or IO formation (Jungwirth and Winter 2008). The involvement of snow micro-algae in the production of halo-compounds such as CHBr3 and CH2Br2 in Antarctica cannot, of course, be ignored following the measurement of these compounds by Sturges and co-workers over 15 years ago (Sturges et al 1993). And the measurement of high levels of nutrient discussed in the recent work by Antony et al (2010) in the ice-cap areas do provide a basis for understanding why micro- algae growth in snow might be promoted. However the question still comes back to: how are these halo-compounds processed to produce 'active' species like BrO radicals, HOBr, Br atoms, Br2 gas or interhalogens such as BrCl? The

  15. Role of correlations in spin-polarized neutron matter

    NASA Astrophysics Data System (ADS)

    Vidaña, Isaac; Polls, Artur; Durant, Victoria

    2016-11-01

    Background: The possible existence of a phase transition to a ferromagnetic state in neutron matter as origin of the extremely high magnetic fields of neutron stars is still an open issue. Whereas many phenomenological interactions predict this transition at densities accessible in neutron stars, microscopic calculations based on realistic interactions show no indication of it. The existence or non-existence of this transition is a consequence of the different role of nucleon-nucleon correlations in polarized and unpolarized neutron matter. Therefore, to give a definite answer to this issue it is necessary to analyze the behavior of these correlations. Purpose: Using the Hellmann-Feynman theorem we analyze the contribution of the different terms of the nucleon-nucleon interaction to the spin symmetry energy of neutron matter with the purpose of identifying the nature and role of correlations in polarized and unpolarized neutron matter. Methods: The analysis is performed within the microscopic Brueckner-Hartree-Fock approach using the Argonne V18 realistic potential plus the Urbana IX three-body force. Results: Our results show no indication of a ferromagnetic transition as the spin symmetry energy of neutron matter is always an increasing function of density. They show also that the main contribution to it comes from the S =0 channel, acting only in non-polarized neutron matter, in particular from the 1S0 and the 1D2 partial waves. Three-body forces are found to play a secondary role in the determination of the spin symmetry energy. Conclusions: By evaluating the kinetic energy difference between the correlated system and the underlying Fermi sea to estimate the importance of correlations in spin-polarized neutron matter, we conclude that non-polarized neutron matter is more correlated than totally polarized one.

  16. Electrodynamics of the high-latitude mesosphere

    NASA Technical Reports Server (NTRS)

    Goldberg, Richard A.

    1989-01-01

    The discovery of apparent large (V/m) electric fields within the mesosphere suggests that this region is more active electrically than originally suspected. High-latitude observations have been particularly productive in developing new concepts regarding mesospheric electrodynamics. Several high-latitude observations of large mesospheric fields have been made under both quiet and aurorally active conditions but always below heights where enhanced ionizing radiations could significantly penetrate. Two measurements from Andoya, Norway, have also produced an anticorrelation of horizontal electric field directions with neutral wind velocities, leading to the theoretical description of a newly defined mechanism for V/m electric field generation involving wind-induced separation of charged aerosols. Evidence for mesospheric aerosols and winds exists at all latitudes but is most evident at high latitudes during the appearance of noctilucent and/or polar mesospheric clouds.

  17. Spin Polarization in High Density Quark Matter

    NASA Astrophysics Data System (ADS)

    Bohr, Henrik; Panda, Prafulla K.; Providência, Constança; da Providência, João

    2013-04-01

    We investigate the occurrence of a ferromagnetic phase transition in high density hadronic matter (e.g., in the interior of a neutron star). This could be induced by a four-fermion interaction analogous to the one which is responsible for chiral symmetry breaking in the Nambu-Jona-Lasinio model, to which it is related through a Fierz transformation. Flavor SU(2) and flavor SU(3) quark matter are considered. A second-order phase transition is predicted at densities about 5 times the normal nuclear matter density. It is also found that in flavor SU(3) quark matter, a first-order transition from the so-called 2 flavor super-conducting phase to the ferromagnetic phase arises. The color-flavor-locked phase may be completely hidden by the FP.

  18. Polar cap mesosphere wind observations: comparisons of simultaneous measurements with a Fabry-Perot interferometer and a field-widened Michelson interferometer.

    PubMed

    Fisher, G M; Killeen, T L; Wu, Q; Reeves, J M; Hays, P B; Gault, W A; Brown, S; Shepherd, G G

    2000-08-20

    Polar cap mesospheric winds observed with a Fabry-Perot interferometer with a circle-to-line interferometer optical (FPI/CLIO) system have been compared with measurements from a field-widened Michelson interferometer optimized for E-region winds (ERWIN). Both instruments observed the Meinel OH emission emanating from the mesopause region (approximately 86 km) at Resolute Bay, Canada (74.9 degrees N, 94.9 degrees W). This is the first time, to our knowledge, that winds measured simultaneously from a ground-based Fabry-Perot interferometer and a ground-based Michelson interferometer have been compared at the same location. The FPI/CLIO and ERWIN instruments both have a capability for high temporal resolution (less than 10 min for a full scan in the four cardinal directions and the zenith). Statistical comparisons of hourly mean winds for both instruments by scatterplots show excellent agreement, indicating that the two optical techniques provide equivalent observations of mesopause winds. Small deviations in the measured wind can be ascribed to the different zenith angles used by the two instruments. The combined measurements illustrate the dominance of the 12-h wave in the mesopause winds at Resolute Bay, with additional evidence for strong gravity wave activity with much shorter periods (tens of minutes). Future operations of the two instruments will focus on observation of complementary emissions, providing a unique passive optical capability for the determination of neutral winds in the geomagnetic polar cap at various altitudes near the mesopause.

  19. Polarizing matter and antimatter: A new method

    SciTech Connect

    Onel, Y.

    1992-02-01

    Several years ago a self-polarization effect for stored (anti)- protons and ions was investigated theoretically. The effect is based on the well-known Stern-Gerlach effect in gradient fields. The aim of the ongoing measurements at the Indiana University Cyclotron Facility (IUCF) is to verify experimentally the various assumptions on which this effect is based. The final goal is to demonstrate this new polarization effect. The proposed effect could be a powerful tool to produce polarized stored hadron beams both in the low-energy range and at SSC and LHC energies. In this progress report we will describe our progress in three parts: (A) Experimental work at IUCF Cooler Ring; (B) Our extensive computer simulations of the spin stability for the IUCF Cooler Ring; and (C) Theoretical studies.

  20. Relativistic Static Thin Disks of Polarized Matter

    NASA Astrophysics Data System (ADS)

    Navarro, Anamaria; Lora-Clavijo, F. D.; González, Guillermo A.

    2017-03-01

    An infinite family of exact solutions of the electrovacuum Einstein-Maxwell equations is presented. The family is static, axially symmetric and describe thin disks composed by electrically polarized material in a conformastatic spacetime. The form of the conformastatic metric allows us to write down the metric functions and the electromagnetic potentials in terms of a solution of the Laplace equation. We find a general expression for the surface energy density of the disk, the pressure, the polarization vector, the electromagnetic fields and the velocity rotation for circular orbits. As an example, we present the first model of the family and show the behavior of the different physical variables.

  1. Seasonal variations of stratospheric gravity waves in Antarctica and correlations to polar mesospheric cloud brightness in summer

    NASA Astrophysics Data System (ADS)

    Yamashita, C.; Chu, X.; Huang, W.; Nott, G. J.; Espy, P. J.

    2007-12-01

    Gravity waves (GWs) play an important role in the dynamics of global middle and upper atmosphere. However, quantitative characterization of GWs in the upper stratosphere is still rare in Antarctica. Here we present a study of stratospheric GW parameters and seasonal variations using the data obtained with the University of Illinois Fe Boltzmann/Rayleigh lidar at the South Pole (90°S) from December 1999 to January 2001 and at Rothera (67.5°S, 68.0°W) from December 2002 to March 2005. Through analyzing the Rayleigh lidar density data in 30-60 km, GW parameters are derived for the South Pole and Rothera, and the results are comparable. The annual mean GW vertical wavelength is 4.3 +/- 1.5 km, vertical phase speed is 0.33 +/- 0.15 m/s, and the period is 245 +/- 110 min. We characterize the stratospheric GW strength with the root- mean-square (RMS) relative density perturbation. The seasonal variation of GW strength is clear at Rothera, with the maximum in winter and the minimum in summer. No significant seasonal variations are observed at the South Pole. The data also show that the GW period is shorter in summer than in winter at Rothera. In addition, the stratospheric GW strength is negatively correlated with PMC brightness at Rothera but no significant correlation at the South Pole. Two important factors, i.e., the wind filtering effect and topographical GW source difference, are investigated in order to explain the GW seasonal variations. We then apply a GW ray-tracing model to analyze the GW source and propagation. The correlation between GW strength and PMC brightness also provides a clue of GW propagation from the stratosphere to the mesosphere.

  2. Medium polarization and pairing in asymmetric nuclear matter

    NASA Astrophysics Data System (ADS)

    Dong, J. M.; Lombardo, U.; Zhang, H. F.; Zuo, W.

    2017-01-01

    The many-body theory of asymmetric nuclear matter is developed beyond the Brueckner-Hartree-Fock approximation to incorporate the medium polarization effects. The extension is performed within the Babu-Brown induced interaction theory. After deriving the particle-hole interaction in the form of Landau-Migdal parameters, the effects of the induced component on the symmetry energy are investigated along with the screening of 1 S 0 proton-proton and 3 PF 2 neutron-neutron pairing, which are relevant for the neutron-star cooling. The crossover from repulsive (screening) to attractive (anti-screening) interaction going from pure neutron matter to symmetric nuclear matter is discussed.

  3. Thermal and dynamical perturbations in the winter polar mesosphere-lower thermosphere region associated with sudden stratospheric warmings under conditions of low solar activity

    NASA Astrophysics Data System (ADS)

    Lukianova, Renata; Kozlovsky, Alexander; Shalimov, Sergey; Ulich, Thomas; Lester, Mark

    2015-06-01

    The upper mesospheric neutral winds and temperatures have been derived from continuous meteor radar (MR) measurements over Sodankyla, Finland, in 2008-2014. Under conditions of low solar activity pronounced sudden mesospheric coolings linked to the major stratospheric warming (SSW) in 2009 and a medium SSW in 2010 are observed while there is no observed thermal signature of the major SSW in 2013 occurred during the solar maximum. Mesosphere-ionosphere anomalies observed simultaneously by the MR, the Aura satellite, and the rapid-run ionosonde during a period of major SSW include the following features. The mesospheric temperature minimum occurs 1 day ahead of the stratospheric maximum, and the mesospheric cooling is almost of the same value as the stratospheric warming (~50 K), the former decay faster than the latter. In the course of SSW, a strong mesospheric wind shear of ~70 m/s/km occurs. The wind turns clockwise (anticlockwise) from north-eastward (south-eastward) to south-westward (north-westward) above (below) 90 km. As the mesospheric temperature reaches its minimum, the gravity waves (GW) in the ionosphere with periods of 10-60 min decay abruptly while the GWs with longer periods are not affected. The effect is explained by selective filtering and/or increased turbulence near the mesopause.

  4. First simultaneous and co-located measurements of the overshoot effect in the Polar Mesosphere Summer Echoes at 56 and 224 MHz

    NASA Astrophysics Data System (ADS)

    Pinedo, H.; La Hoz, C.; Senior, A.; Havnes, O.; Rietveld, M.; Kosch, M. J.

    2014-12-01

    We report the first observations at 56 MHz (MORRO radar) of the overshoot effect in the polar mesosphere summer echoes (PMSE) when they are subject to artificial high power HF pulsed waves (Heating). Statistics indicate that there is an overall overshoot at this frequency despite of the high fluctuation of the backscatter. Simultaneous and co-located PMSE measurements at 224 MHz (EISCAT VHF radar) show also the overshoot effect. This experimental campaign was done around the peak of the PMSE season in 2013. The overall effect of the active modification of the PMSE strength is studied through the overshoot characteristic curve (OCC). At 224 MHz, available PMSE OCC measurements and modeling results indicate that during Heating the time scale of electron diffusion is shorter than the charging of dust particles. In this way, the free electron Bragg scatter structures surrounding dust particles are dispersed right after the Heating is turned on and leading to a decrease of the PMSE strength which can be followed by a recovery due to a slight increase of dust particle charging while the pulse is still active. Once the Heating is turned-off, the electrons cool down almost instantaneously and adopt the spatial distribution defined by dust particles, which at this time they are expected to be more charged due to influx of electrons. A highlight in this study is that we found some particular cases at 56MHz and 224MHz indicating that dust charging may overcome the diffusion process. This condition is known as the onset overshoot in which the backscatter increases after the heater was switched on. We have resorted to available models of the PMSE OCC at these two frequencies for finding similarities with our observations; especially those related to the onset overshoot. Through this evaluation we provide discussions about the differences between present measurements and model results, and plausible interpretation of physical conditions of particles and processes constituting

  5. Effect of polarization on superfluidity in low density neutron matter

    NASA Technical Reports Server (NTRS)

    Clark, J. W.; Kallman, C.-G.; Yang, C.-H.; Chakkalakal, D. A.

    1976-01-01

    The singlet-state quasi-particle interaction in neutron matter is examined on the basis of results of a detailed evaluation of the Landau Fermi-liquid parameters for pure neutron effects, including polarization effects. This means that the interaction induced by exchange of density and spin-density excitations is taken into account. It is shown that polarization actually works to suppress the pairing matrix elements, owing to the spin dependence of the quasi-particle interaction and, ultimately, the balance of attraction, repulsion, and spin dependence in the fundamental two-neutron interaction. Since the isotropic energy gap and the condensation energy in low-density neutron-star matter are extremely sensitive functions of the pairing matrix elements, they will also be suppressed by the polarizability of the neutron medium.

  6. Nonthermal dark matter and the top polarization at collider

    SciTech Connect

    Gao, Yu

    2016-06-21

    We discuss the characteristic collider signatures, in particular a highly polarized resonant single-top channel for a minimal color triplet extension to the Standard Model. This extension provides baryogensis and a non-thermal production history of a dark matter candidate. We further discuss the implementation of both completely left and right-handed chiral interaction in the model and the difference in phenomenology between the two scenarios. If the color triplets are isospin singlets, the dark matter candidate mass is 1 GeV and the single-top quarks are strictly right-handed polarized. Alternatively, the isospin-doublet color triplets lead to strictly left-handed single top events and a more extended particle spectrum.

  7. Spectral Induced Polarization Signature of Soil Organic Matter

    NASA Astrophysics Data System (ADS)

    Schwartz, Nimrod; Furman, Alex

    2015-04-01

    Although often composing a non-negligible fraction of soil cation exchange capacity (CEC), the impact of soil organic matter (OM) on the electrical properties of soil has not been thoroughly investigated. In this research the impact of soil OM on the spectral induced polarization (SIP) signature of soil was investigated. Electrical and chemical measurements for two experiments using the same soil, one with calcium as the dominant cation and the other with sodium, with different concentration of OM were performed. Our results show that despite the high CEC of OM, a decrease in polarization and an increase in relaxation time with increasing concentration of OM is observed. For the soil with calcium as the dominant cation, the decreases in polarization and the increase in relaxation time were stronger. We explain these non-trivial results by accounting for the interactions between the OM and the soil minerals. We suggest that the formation of organo-mineral complexes reduce ionic mobility, explaining both the decrease in polarization and the increase in relaxation time. These results demonstrate the important role of OM on SIP response of soil, and call for a further research in order to establish a new polarization model that will include the impact of OM on soil polarization.

  8. On the spectral induced polarization signature of soil organic matter

    NASA Astrophysics Data System (ADS)

    Schwartz, N.; Furman, A.

    2015-01-01

    Although often composing a non-negligible fraction of soil cation exchange capacity (CEC), the impact of soil organic matter (OM) on the electrical properties of soil has not been thoroughly investigated. In this research the impact of soil OM on the spectral induced polarization (SIP) signature of soil was investigated. Electrical and chemical measurements for two experiments using the same soil, one with calcium as the dominant cation and the other with sodium, with different concentration of OM were performed. Our results show that despite the high CEC of OM, a decrease in polarization and an increase in relaxation time with increasing concentration of OM is observed. For the soil with calcium as the dominant cation, the decreases in polarization and the increase in relaxation time were stronger. We explain these non-trivial results by accounting for the interactions between the OM and the soil minerals. We suggest that the formation of organo-mineral complexes reduce ionic mobility, explaining both the decrease in polarization and the increase in relaxation time. These results demonstrate the important role of OM on SIP response of soil, and call for a further research in order to establish a new polarization model that will include the impact of OM on soil polarization.

  9. SMM mesospheric ozone measurements

    NASA Technical Reports Server (NTRS)

    Aikin, A. C.

    1990-01-01

    The main objective was to understand the secular and seasonal behavior of ozone in the lower mesosphere, 50 to 70 km. This altitude region is important in understanding the factors which determine ozone behavior. A secondary objective is the study of stratospheric ozone in the polar regions. Use is made of results from the SBUV satellite borne instrument. In the Arctic the interaction between chlorine compounds and low molecular weight hydrocarbons is studied. More than 30,000 profiles were obtained using the UVSP instrument on the SMM spacecraft. Several orbits of ozone data per day were obtained allowing study of the current rise in solar activity from the minimum until the present. Analysis of Nimbus 7 SBUV data in Antarctic spring indicates that ozone is depleted within the polar vortex relative to ozone outside the vortex. This depletion confirms the picture of ozone loss at altitudes where polar stratospheric clouds exist. In addition, there is ozone loss above the cloud level indicating that there is another mechanism in addition to ozone loss initiated by heterogeneous chlorine reactions on cloud particles.

  10. Simulataneous observations of polar mesosphere winter echo and cosmic noise absorption based on the PANSY radar in the Antarctic (69.0°S, 39.6°E)

    NASA Astrophysics Data System (ADS)

    Nishiyama, Takanori; Nakamura, Takuji; Tsutsumi, Masaki; Tanaka, Yoshi; Sato, Toru; Nishimura, Koji; Sato, Kaoru; Tomikawa, Yoshihiro; Kohma, Masashi

    2016-07-01

    In the Mesosphere and lower Thermosphere, both neutral turbulence and ionization of atmosphere due to solar radiations cause irregularities of refractive index, and as a result back scatter echoes from that altitude are frequently observed by radars on the ground. In the mesosphere, Polar Mesosphere Winter Echo (PMWE) is known as back scatter echo from 55 to 85 km in the mesosphere, and it has been observed by MST and IS radar in polar region during non-summer period. PMWE occurrence rate is known to be quite low (2.9%) [Zeller et al., 2006], partly because density of free electrons as scatterer is low in the dark mesosphere during winter. Thus, it is suggested that PMWE requires strong ionization of neutral atmosphere associated with Energetic Particles Precipitations (EPPs) during Solar Proton Events [Kirkwood et al., 2002] or during geomagnetically disturbed periods [Nishiyama et al., 2015]. However, direct comparison between occurrence of PMWE and background electron density by in-situ measurements has been limited yet [e.g., Luebken et al., 2006]. Neutral turbulence associated with breaking of atmospheric gravity waves is also important and its contribution to PMWE generation should be evaluated. The PANSY (Program of the Antarctic Syowa MST/IS) radar, which is the largest MST radar in Antarctica, observed many PMWE events since it has started mesosphere observations in June 2012. In addition, we established an application method of the PANSY radar as riometer, which makes it possible to estimate Cosmic Noise Absorptions (CNA) as proxy of relative variations on background electron density. In addition, electron density profiles from 60 to 150 km altitude are calculated by Ionospheric Model for the Auroral Zone (IMAZ) [McKinnell and Friedrich, 2007] and CNA estimated by the PANSY radar. In this presentation, we would like to focus on simultaneous PMWE and CNA observation on May 23, 2013 when large SPE took place in order to evaluate contributions of relative

  11. Observation of atomic oxygen O(1S) green-line emission in the summer polar upper mesosphere associated with high-energy (≥30 keV) electron precipitation during high-speed solar wind streams

    NASA Astrophysics Data System (ADS)

    Lee, Young-Sook; Kwak, Young-Sil; Kim, Kyung-Chan; Solheim, Brian; Lee, Regina; Lee, Jaejin

    2017-01-01

    The auroral green-line emission at 557.7 nm wavelength as arising from the atomic oxygen O(1S → 1D) transition typically peaks at an altitude of 100 km specifically in the nightside oval, induced by auroral electrons within an energy range of 100 eV-30 keV. Intense aurora is known as being suppressed by sunlight in summer daytime but usually occurs in low electrical background conductivity. However, in the present study in summer (July) sunlit condition, enhancements of O(1S) emission rates observed by using the Wind Imaging Interferometer/UARS were frequently observed at low altitudes below 90 km, where ice particles are created initially as subvisible and detected as polar mesosphere summer echoes, emerging to be an optical phenomenon of polar mesospheric clouds. The intense O(1S) emission occurring in summer exceeds those occurring in the daytime in other seasons both in occurrence and in intensity, frequently accompanied by occurrences of supersonic neutral velocity (300-1500 m s-1). In the mesosphere, ion motion is controlled by electric field and the momentum is transferred to neutrals. The intense O(1S) emission is well associated with high-energy electron precipitation as observed during an event of high-speed solar wind streams. Meanwhile, since the minimum occurrences of O(1S) emission and supersonic velocity are maintained even in the low precipitation flux, the mechanism responsible is not only related to high-energy electron precipitation but also presumably to the local conditions, including the composition of meteoric-charged ice particles and charge separation expected in extremely low temperatures (<150 K).

  12. A study of the origin, nature, and behavior of particulate matter and metallic atoms in the mesosphere, lower thermosphere, and at the mesopause. [using lidar data

    NASA Technical Reports Server (NTRS)

    Poultney, S. K.

    1973-01-01

    In a study of particulate matter and metallic atoms in the vicinity of the mesopause, three areas have received the most effort. These areas are: the significance of cometary dust influxes to the earth's atmosphere; the relation of nightglows to atmospheric motions and aerosols; and the feasibility of using an airborne resonant scatter lidar to study polar noctilucent clouds, the sodium layer, and fireball dust.

  13. Polar Mesospheric Waves and Structure

    DTIC Science & Technology

    1993-05-01

    1 1 1 4:1 93--1.2336 i .* .:: *• lIIlIli hiiIIIl~lii SDL/93-039 Page i May 1993 FORWORD * The Department of the Navy/Office of Naval Research awarded...that the inner scale of the electron fluctuation spectrum decreases at least as fast as e- 1/4, which is the case for neutral turbulence. ŔI I SDL

  14. Aeronomy of Ice in the Mesosphere (AIM)

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The overall goal of the Aeronomy of Ice in the Mesosphere (AIM) experiment is to resolve why Polar Mesospheric Clouds form and why they vary. By measuring PMCs and the thermal, chemical and dynamical environment in which they form, we will quanti@ the connection between these clouds and the meteorology of the polar mesosphere. In the end, this will provide the basis for study of long-term variability in the mesospheric climate and its relationship to global change. The results of AIM will be a rigorous validation of predictive models that can reliably use past PMC changes and present trends as indicators of global change. The AIM goal will be achieved by measuring PMC extinction, brightness, spatial distribution, particle size distributions, gravity wave activity, dust influx to the atmosphere and precise, vertical profile measurements of temperature, H20, C&, 0 3 , C02, NO. and aerosols. These data can only be obtained by a complement of instruments on an orbiting spacecraft (S/C).

  15. Enhanced horizontal extreme-echo speed occurrence leading to polar mesospheric summer echoes (PMSE) increase at solar-wind pressure enhancement during high-speed solar wind stream events

    NASA Astrophysics Data System (ADS)

    Lee, Y.; Kirkwood, S.; Kwak, Y.; Kim, K.; Shepherd, G. G.

    2013-12-01

    We report on horizontal extreme echo speeds (HEES, ≥ 300 ms^{-1}) observed in long-periodic polar mesospheric summer echoes (PMSE) correlated with solar-wind speed in high speed solar wind streams (HSS) events. The observations were made from VHF 52 MHz radar measurements at Esrange (67.8°N, 20.4°E) between June 1-August 8 in 2006 and 2008. The periodicities of PMSE counts and the volume reflectivity primarily occur at 7, 9 and 13.5 days possibly by the effects of HSS, while the periodicities at 4-6 days are competitively coherent between planetary waves appearing in temperature and solar-wind speed during HSS events. The peaks of both HEES occurrence rate relative to PMSE and turbulence dominantly occur at solar-wind pressure enhancement with minor peaks continued under the passage of HSS over the magnetopause, followed by PMSE peaks in 1-3 days later. This study gives the results that the precipitating high-energetic particles (> 30 keV) during HSS likely induce D-region ionization involved with the consecutive processes of HEES, turbulence and PMSE. The turbulence evolved from the HEES can be explained with the Kelvin-Helmholtz instability, which was observed in PMSE by Röttger et al. [11th International Workshop on technical and scientific aspects of MST Radar, 2006] and firstly simulated for PMSE generation by Hill et al. [Earth Planets Space, 1999]. The HEES is understood as the speed of fast moving ions, accelerated by strong electric field as Lee & Shepherd [JGR, 2010] suggested with the supersonic velocities persisting in polar mesospheric clouds (PMC) region observed at enhanced O(^1S) emission rate ( 10 kR) by WINDII/UARS satellite.

  16. Towards a quantitative kinetic theory of polar active matter

    NASA Astrophysics Data System (ADS)

    Ihle, T.

    2014-06-01

    A recent kinetic approach for Vicsek-like models of active particles is reviewed. The theory is based on an exact Chapman- Kolmogorov equation in phase space. It can handle discrete time dynamics and "exotic" multi-particle interactions. A nonlocal mean-field theory for the one-particle distribution function is obtained by assuming molecular chaos. The Boltzmann approach of Bertin, et al., Phys. Rev. E 74, 022101 (2006) and J. Phys. A 42, 445001 (2009), is critically assessed and compared to the current approach. In Boltzmann theory, a collision starts when two particles enter each others action spheres and is finished when their distance exceeds the interaction radius. The average duration of such a collision, τ0, is measured for the Vicsek model with continuous time-evolution. If the noise is chosen to be close to the flocking threshold, the average time between collisions is found to be roughly equal to τ0 at low densities. Thus, the continuous-time Vicsek-model near the flocking threshold cannot be accurately described by a Boltzmann equation, even at very small density because collisions take so long that typically other particles join in, rendering Boltzmann's binary collision assumption invalid. Hydrodynamic equations for the phase space approach are derived by means of a Chapman-Enskog expansion. The equations are compared to the Toner-Tu theory of polar active matter. New terms, absent in the Toner-Tu theory, are highlighted. Convergence problems of Chapman-Enskog and similar gradient expansions are discussed.

  17. Thermodynamics of homogeneous nucleation of mesospheric ice particles

    NASA Astrophysics Data System (ADS)

    Zasetsky, A. Y.; Petelina, S. V.

    2009-05-01

    Although our knowledge of the upper mesospheric region is continuously improving, many aspects of mesospheric dynamics and thermodynamics are still unclear. We address some of these open questions related to the thermodynamics of water at the conditions intrinsic for the polar summer mesosphere. For this we use recently published theoretical and laboratory results on the properties of water at very low temperatures. We present the hypothesis of homogeneous nucleation of ice nano-particles in the polar summer mesosphere. The nucleation of condensed phase is traced back to the first step on the formation pathway, which is assumed to be the transition of water vapor to amorphous cluster. Amorphous clusters then freeze into water ice, likely metastable cubic ice, when they reach the critical size. The estimates based on the equilibrium thermodynamics give the critical size (radius) of amorphous water clusters as about 1.0 nm. The same estimates for the final transition step, that is the transformation of cubic to hexagonal ice, give the critical size of about 15 nm at typical upper mesospheric conditions during the polar summer (about 150K temperature and about 109cm-3 water vapor density).

  18. Investigation of Mesospheric Metal Emission Signals from SCIAMACHY Limb Measurements

    DTIC Science & Technology

    2013-10-31

    descend into the stratosphere the metal atom and ion clusters may also be condensation nuclei for polar stratospheric clouds in winter and spring at high...latitudes and have an impact on the chemistry of stratospheric ozone. After entry into the troposphere, the metals and their compounds are eventually...polar mesospheric cloud PSC – polar stratospheric cloud Distribution A: Approved for public release; distribution is unlimited. 31 SCD – slant column

  19. The Mega Mesospheric Parachute

    NASA Technical Reports Server (NTRS)

    Kloesel, Kurt J.; Oberto, Robert; Kinsey, Robert

    2005-01-01

    The current understanding and modeling of the upper reaches of the atmosphere is incomplete. Upper atmospheric interactions with the lower atmosphere, effects of ionizing radiation, high altitude cloud phenomena, and the dynamical interaction with the magnetosphere require greater definition. The scientific objective of obtaining a greater understanding of the upper atmosphere can be achieved by designing, implementing, testing, and utilizing a facility that provides long period in-situ measurements of the mesosphere. Current direct sub-sonic measurements of the upper atmosphere are hampered by the approximately one minute sub-sonic observation window of a ballistic sounding rocket regardless of the launch angle. In-situ measurements at greater than transonic speeds impart energy into the molecular atmospheric system and distort the true atmospheric chemistry. A long duration, sub-sonic capability will significantly enhance our ability to observe and measure: (1) mesospheric lightning phenomena (sprites and blue jets) (2) composition, structure and stratification of noctilucent clouds (3) physics of seasonal radar echoes, gravity wave phenomena (4) chemistry of mesospheric gaseous ratio mixing (5) mesospheric interaction of ionizing radiation (6) dynamic electric and magnetic fields This new facility will also provide local field measurements which complement those that can be obtained through external measurements from satellite and ground-based platforms. The 400 foot (approximately 130 meter) diameter lightweight mega-mesospheric parachute system, deployed with a sounding rocket, is proposed herein as a method to increase sub-sonic mesospheric measurement time periods by more than an order of magnitude. The report outlines a multi-year evolving science instrumentation suite in parallel with the development of the mega meso-chute facility. The developmental issues surrounding the meso-chute are chiefly materials selection (thermal and structural) and deployment

  20. Coherent control of light-matter interactions in polarization standing waves

    PubMed Central

    Fang, Xu; MacDonald, Kevin F.; Plum, Eric; Zheludev, Nikolay I.

    2016-01-01

    We experimentally demonstrate that standing waves formed by two coherent counter-propagating light waves can take a variety of forms, offering new approaches to the interrogation and control of polarization-sensitive light-matter interactions in ultrathin (subwavelength thickness) media. In contrast to familiar energy standing waves, polarization standing waves have constant electric and magnetic energy densities and a periodically varying polarization state along the wave axis. counterintuitively, anisotropic ultrathin (meta)materials can be made sensitive or insensitive to such polarization variations by adjusting their azimuthal angle. PMID:27514307

  1. Coherent control of light-matter interactions in polarization standing waves

    NASA Astrophysics Data System (ADS)

    Fang, Xu; MacDonald, Kevin F.; Plum, Eric; Zheludev, Nikolay I.

    2016-08-01

    We experimentally demonstrate that standing waves formed by two coherent counter-propagating light waves can take a variety of forms, offering new approaches to the interrogation and control of polarization-sensitive light-matter interactions in ultrathin (subwavelength thickness) media. In contrast to familiar energy standing waves, polarization standing waves have constant electric and magnetic energy densities and a periodically varying polarization state along the wave axis. counterintuitively, anisotropic ultrathin (meta)materials can be made sensitive or insensitive to such polarization variations by adjusting their azimuthal angle.

  2. Can spin-polarized photoemission measure spin properties in condensed matter?

    PubMed

    Osterwalder, Jürg

    2012-05-02

    Photoemitted electrons move in a vacuum; their quantum state can be completely characterized in terms of energy, momentum and spin polarization by spin-polarized photoemission experiments. A review article in this issue by Heinzmann and Dil (2012 J. Phys.: Condens. Matter 24 173001) considers whether the measured spin properties, i.e. the magnitude and direction of the spin polarization vector, can be traced back to the quantum state from which these electrons originate. The careful conclusion is that they can, which is highly relevant in view of the current interest in these experiments and their application to topological insulators, where the spin-orbit interaction produces spin-polarized surface states.

  3. Stratospheric Impact on the Onset of the Mesospheric Ice Season

    NASA Astrophysics Data System (ADS)

    Fiedler, J.; Baumgarten, G.; Berger, U.; Gabriel, A.; Latteck, R.; Luebken, F. J.

    2014-12-01

    Mesospheric ice layers, observed as noctilucent clouds (NLC) from ground, are the visible manifestation of extreme conditions in the polar summer mesopause region. Temperatures fall very low so that water vapor can freeze condence, which at 69°N usually occurs beginning of June. However, in 2013 the ALOMAR RMR lidar observed the first NLC on 21 May and the clouds reoccured during the following days. These were the earliest detections since 20 years and indicated an about 10 days earlier onset of the mesospheric ice season. This is supported by the colocated MAARSY radar which showed the occurrence rates of polar mesospheric summer echoes (PMSE) increasing faster than usual.The exceptional case was accompanied by ˜6 K lower temperatures and higher water vapor mixing ratios at NLC altitudes above ALOMAR from end of April until beginning of June as measured by the MLS instrument onboard the AURA satellite. Using MERRA reanalysis data we will show that the zonal mean temperature as well as the dynamic conditions in the Arctic middle atmosphere deviated in spring 2013 significantly from the mean conditions of the last 20 years. The planetary wave activity in the high latitude stratosphere was enhanced from 20 April to beginning of May. The colder and wetter upper mesosphere in May 2013 is attributed to this unusual late planetary wave activity in the stratosphere, introducing a strong upwelling in the mesosphere, lower temperatures and an upward transport of water vapor, which finally resulted into earlier existence conditions for mesospheric ice particles. For the southern hemisphere a high correlation between winter/summer transition in the stratosphere and onset of mesospheric ice is known as intra-hemispheric coupling. We regard the processes in the Arctic middle atmosphere in spring 2013 as a first evidence for intra-hemispheric coupling in the northern hemisphere, extending from the stratosphere into the mesopause region.

  4. Characterization of polar organics in airborne particulate matter

    NASA Astrophysics Data System (ADS)

    Yokouchi, Y.; Ambe, Y.

    The methanol-extractable highly polar organics in atmospheric aerosol were characterized using GC-MS. Dicarboxylic acids having 2-16 carbon numbers were detected with a total concentration of 172 ng m -3. Azelaic acid ( C9) was the most abundant diacid and it possibly originated from the ozonolysis of unsaturated carboxylic acids such as oleic acid and linoleic acid, which mainly originate from terrestrial plants. A compound, which was tentatively identified as tetrahydrofuroic acid, contributed to about 10% of the highly polar organics. Other polyfunctional compounds found in the samples included some ketocarboxylic acids and aromatic acids such as phthalic acids, anisic acid and vanillic acid.

  5. Mesospheric gravity-wave climatology at Adelaide

    NASA Technical Reports Server (NTRS)

    Vincent, R. A.

    1986-01-01

    The MF Adelaide partial-reflection radar has been operating continuously since November 1983. This has enabled a climatology of gravity-wave activity to be constructed for the mesosphere. The data have been analyzed for a medium-period range of 1 to 8 hr. and a longer period range between 8 and 24 hr. covering the inertio-period waves. The tidal motions have been filtered out prior to analysis. For the data analyses so far (Nov. 1983 to Dec. 1984), a number of interesting features emerged. Firstly, the wave activity at heights above 80 km shows a small seimannual variation with season with the activity being strongest in summer and winter. At heights below 80 km however, there is a similar but more marked variation with the weakest amplitudes occurring at the time of the changeovers in the prevailing circulation. If breaking gravity waves are responsible for much of the turbulence in the mesosphere, then the periods March to April and September to October might also be expected to be periods of weak turbulence. The wave field appears to be partially polarized. The meridional amplitudes are larger than the zonal amplitudes, especially in water. It is found that the degree of polarization is about 15% in summer and 30% in winter. The polarized component is found to propagate in the opposite direction to the background flow in the stratosphere, which suggests that the polarization arises through directional filtering of the waves as they propagate up from below.

  6. Sounding Rocket Particle Sampling in the Mesosphere

    NASA Astrophysics Data System (ADS)

    Waldemarsson, T.; Giovane, F.; Stroud, R. M.; Gumbel, J.; Hedin, J.; Blum, J.; Reissaus, P.; Siskind, D. E.; Stegman, J.; Khaplanov, M.

    Current estimates suggest that somewhere between 10 and 100 tons of meteoric material enters the Earth atmosphere each day It is well known that the ablation of this incoming material is the source of metal atoms and ions regularly observed in the upper atmosphere by remote sensing techniques such as lidar and satellite limb measurements What happens next is more uncertain but subsequent condensation and coagulation of the ablated material is thought to form nanometer-size particles also denoted meteoric smoke It has been suggested that meteoric smoke plays a key role in a number of mesospheric processes related to e g noctilucent clouds NLC and polar mesosphere summer echos PMSE We will present a recently developed instrument MAGIC Mesospheric Aerosol - Genesis Interaction and Composition designed for in situ sampling of smoke particles during a sounding rocket flight The MAGIC instrument has been built at the Naval Research Laboratory with particular emphasis on aerodynamic challenges imposed by the tiny size of the particles By sampling smoke particles and making them available for laboratory analysis their existence and properties can be studied Basic questions concern their number density size altitude distribution and composition The first flights of the MAGIC instrument took place at Esrange Sweden in January 2005 and at Wallops Island USA in May 2005 An overview of the campaigns will be presented together with preliminary results from the transmission electron microscopy analysis carried out on these first flown collection

  7. Joule heating in the high-latitude mesosphere

    NASA Technical Reports Server (NTRS)

    Banks, P. M.

    1979-01-01

    The contribution made by Joule dissipation to heating of the daytime high-latitude upper mesosphere is discussed. During solar proton precipitation events in regions of large electric fields, Joule dissipation can be substantially larger than the local solar heating rate. Altitude profiles of Joule dissipation are presented for the polar cleft region for the August 4, 1972, solar proton event.

  8. Spin polarization versus color-flavor locking in high-density quark matter

    NASA Astrophysics Data System (ADS)

    Tsue, Yasuhiko; da Providência, João; Providência, Constança; Yamamura, Masatoshi; Bohr, Henrik

    2015-01-01

    It is shown that spin polarization with respect to each flavor in three-flavor quark matter occurs instead of color-flavor locking at high baryon density by using the Nambu-Jona-Lasinio model with four-point tensor-type interaction. Also, it is indicated that the order of phase transition between the color-flavor-locked phase and the spin-polarized phase is the first order by means of second-order perturbation theory.

  9. Characterization and origin of polar dissolved organic matter from the Great Salt Lake

    USGS Publications Warehouse

    Leenheer, J.A.; Noyes, T.I.; Rostad, C.E.; Davisson, M.L.

    2004-01-01

    Polar dissolved organic matter (DOM) was isolated from a surface-water sample from the Great Salt Lake by separating it from colloidal organic matter by membrane dialysis, from less-polar DOM fractions by resin sorbents, and from inorganic salts by a combination of sodium cation exchange followed by precipitation of sodium salts by acetic acid during evaporative concentration. Polar DOM was the most abundant DOM fraction, accounting for 56% of the isolated DOM. Colloidal organic matter was 14C-age dated to be about 100% modern carbon and all of the DOM fractions were 14C-age dated to be between 94 and 95% modern carbon. Average structural models of each DOM fraction were derived that incorporated quantitative elemental and infrared, 13C-NMR, and electrospray/mass spectrometric data. The polar DOM model consisted of open-chain N-acetyl hydroxy carboxylic acids likely derived from N-acetyl heteropolysaccharides that constituted the colloidal organic matter. The less polar DOM fraction models consisted of aliphatic alicyclic ring structures substituted with carboxyl, hydroxyl, ether, ester, and methyl groups. These ring structures had characteristics similar to terpenoid precursors. All DOM fractions in the Great Salt Lake are derived from algae and bacteria that dominate DOM inputs in this lake.

  10. Equation of state of hot polarized nuclear matter using the generalized Skyrme interaction

    NASA Astrophysics Data System (ADS)

    Abd-Alla, M.; Hager, S. A.

    2000-04-01

    We used the generalized Skyrme potential to study the equation of state of polarized nuclear matter in the frame of the Thomas-Fermi model. The critical temperature of the liquid-gas phase transition is found to be Tc=16.2 MeV. This critical temperature was found to decease with the asymmetry, spin, and spin-isospin excess parameters. The isothermal compressibility of polarized nuclear matter was also studied. The volume compressibility Kv was found to decrease with temperature. The symmetry compressibility Kx, the spin symmetry compressibility Ky, and the spin-isospin symmetry compressibility Kz were found to have a little increasing behavior with temperature.

  11. Polar Ring Galaxies Favor Milgromian Dynamics over Standard Dark-Matter-Based Models

    NASA Astrophysics Data System (ADS)

    Lüghausen, F.; Famaey, B.; Kroupa, P.

    2014-05-01

    Polar ring galaxies are ideal objects with which to study the 3-dimensional shapes of galactic gravitational potentials since two rotation curves can be measured in two perpendicular planes. Observational studies have uncovered systematically larger rotation velocities in the extended polar rings than in the associated host galaxies. In the dark matter context, this can only be explained through dark halos that are systematically flattened along the polar rings. Here, we point out that these objects can also be used as very effective tests of gravity theories, such as those based on Milgromian dynamics. We run a set of polar ring models using both Milgromian and Newtonian dynamics to predict the expected shapes of the rotation curves in both planes, varying the total mass of the system, the mass of the ring with respect to the host, as well as the size of the hole at the center of the ring. We find that Milgromian dynamics not only naturally leads to rotation velocities being typically higher in the extended polar rings than in the hosts, as would be the case in Newtonian dynamics without dark matter, but that it also gets the shape and amplitude of velocities correct. Observational data on polar ring galaxies thus favour Milgromian dynamics over Newtonian dynamics plus dark matter.

  12. Magnetometry with mesospheric sodium

    PubMed Central

    Higbie, James M.; Rochester, Simon M.; Patton, Brian; Holzlöhner, Ronald; Bonaccini Calia, Domenico; Budker, Dmitry

    2011-01-01

    Measurement of magnetic fields on the few 100-km length scale is significant for many geophysical applications including mapping of crustal magnetism and ocean circulation measurements, yet available techniques for such measurements are very expensive or of limited accuracy. We propose a method for remote detection of magnetic fields using the naturally occurring atomic sodium-rich layer in the mesosphere and existing high-power lasers developed for laser guide star applications. The proposed method offers a dramatic reduction in cost and opens the way to large-scale, parallel magnetic mapping and monitoring for atmospheric science, navigation, and geophysics. PMID:21321235

  13. Solar Mesosphere Explorer

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Five experiments and the instruments packages designed for use in studying reactions between sunlight, ozone, and other chemicals in the atmosphere as well as for determining how ozone concentrations are transported in the mesosphere are described. The spin-stabilized satellite carrying the experiments consists of an observatory module and a spacecraft bus. Powered by a solar array which charges the nickel-cadmium batteries, the satellite is to be inserted into a sun synchronous orbit by a two stage Delta 2310 launch vehicle. The mission objectives, spacecraft configurations, and various subsystems are described as well as the ground support and prelaunch operations.

  14. Mesospheric and thermospheric tides

    NASA Astrophysics Data System (ADS)

    Forbes, J. M.

    1980-08-01

    Recent calculations of atmospheric solar tides in the mesosphere and thermosphere are reviewed. The numerical models considered consist of a full three-dimensional solution of the tidal equations in a rotating viscous spherical atmosphere (Forbes and Garret 1976, 1978), and an approximate solution for some modes given by an equivalent gravity wave on a rotating plane (Forbes and Hagan 1979, 1980). Both models take into account eddy and molecular diffusion of heating and momentum, rotation, and hydromagnetic coupling, and use new calculations of thermal forcing by insolation absorption due to H2O and O3 below 70 km.

  15. Correlation of soil and sediment organic matter polarity to aqueous sorption of nonionic compounds

    USGS Publications Warehouse

    Kile, D.E.; Wershaw, R. L.; Chiou, C.T.

    1999-01-01

    Polarities of the soiL/sediment organic matter (SOM) in 19 soil and 9 freshwater sediment sam pies were determined from solid-state 13C-CP/MAS NMR spectra and compared with published partition coefficients (K(oc)) of carbon tetrachloride (CT) from aqueous solution. Nondestructive analysis of whole samples by solid-state NMR permits a direct assessment of the polarity of SOM that is not possible by elemental analysis. The percent of organic carbon associated with polar functional groups was estimated from the combined fraction of carbohydrate and carboxylamide-ester carbons. A plot of the measured partition coefficients (K(oc)) of carbon tetrachloride (CT) vs. percent polar organic carbon (POC) shows distinctly different populations of soils and sediments as well as a roughly inverse trend among the soil/sediment populations. Plots of K(oc) values for CT against other structural group carbon fractions did not yield distinct populations. The results indicate that the polarity of SOM is a significant factor in accounting for differences in K(oc) between the organic matter in soils and sediments. The alternate direct correlation of the sum of aliphatic and aromatic structural carbons with K(oc) illustrates the influence of nonpolar hydrocarbon on solute partition interaction. Additional elemental analysis data of selected samples further substantiate the effect of the organic matter polarity on the partition efficiency of nonpolar solutes. The separation between soil and sediment samples based on percent POC reflects definite differences of the properties of soil and sediment organic matters that are attributable to diagenesis.Polarities of the soil/sediment organic matter (SOM) in 19 soil and 9 freshwater sediment samples were determined from solid-state 13C-CP/MAS NMR spectra and compared with published partition coefficients (Koc) of carbon tetrachloride (CT) from aqueous solution. Nondestructive analysis of whole samples by solid-state NMR permits a direct

  16. Correlation of soil and sediment organic matter polarity to aqueous sorption of nonionic compounds

    SciTech Connect

    Kile, D.E. ); Wershaw, R.L.; Chiou, C.T. )

    1999-06-15

    Polarities of the soil/sediment organic matter (SOM) in 19 soil and 9 freshwater sediment samples were determined from solid-state [sup 13]C-CP/MAS NMR spectra and compared with published partition coefficients (K[sub oc]) of carbon tetrachloride (CT) from aqueous solution. Nondestructive analysis of whole samples by solid-state NMR permits a direct assessment of the polarity of SOM that is not possible by elemental analysis. The percent of organic carbon associated with polar functional groups was estimated from the combined fraction of carbohydrate and carboxyl-amide-ester carbons. A plot of the measured partition coefficients (K[sub oc]) of carbon tetrachloride (CT) vs. percent polar organic carbon (POC) shows distinctly different populations of soils and sediments as well as a roughly inverse trend among the soil/sediment populations. Plots of K[sub oc] values for CT against other structural group carbon fractions did not yield distinct populations. The results indicate that the polarity of SOM is a significant factor in accounting for differences in K[sub oc] between the organic matter in soils and sediments. The alternate direct correlation of the sum of aliphatic and aromatic structural carbons with K[sub oc] illustrates the influence of nonpolar hydrocarbon on solute partition interaction. Additional elemental analysis data of selected samples further substantiate the effect of the organic matter polarity on the partition efficiency of nonpolar solutes. The separation between soil and sediment samples based on percent POC reflects definite differences of the properties of soil and sediment organic matters that are attributable to diagenesis.

  17. High-latitude remote sensing of mesospheric wind speeds and carbon monoxide

    NASA Astrophysics Data System (ADS)

    Burrows, S. M.; Martin, C. L.; Roberts, E. A.

    2007-09-01

    We present high-resolution ground-based measurements of mesospheric carbon monoxide (CO) taken in the years 2002-5 from the AST/RO sub-millimeter telescope, located at Amundsen-Scott South Pole Station. These include the first winter measurements of CO directly from one of the geographic poles, which agree well with expected high concentrations within the polar vortex. We also use CO as a tracer to estimate mesospheric neutral wind speeds, by measuring small Doppler shifts in the rotational emission spectrum. We highlight the potential of high-resolution radiometric measurements mesospheric winds to fill a significant experimental data gap.

  18. Impact of molecular diffusion on the CO2 distribution and the temperature in the mesosphere

    NASA Astrophysics Data System (ADS)

    Chabrillat, Simon; Kockarts, Gaston; Fonteyn, Dominique; Brasseur, Guy

    2002-08-01

    Modelling the energy budget in the mesosphere and lower thermosphere requires a precise evaluation of CO2 distribution in this region. This distribution is primarily determined by competition between vertical eddy diffusion and molecular diffusion. A simple algorithm is proposed to take into account both processes, at all altitudes. Using the SOCRATES bi-dimensional model of the middle atmosphere, we show that molecular diffusion has a direct impact on CO2 vertical distribution down to approximately 80 km altitude, i.e. well into the mesosphere and below the turbopause altitude. A sensitivity study with regard to different aeronomical processes shows that molecular diffusion has the deepest influence in the mesospheric polar night region. Our model shows that molecular diffusion of CO2 is responsible for a polar night mesopause 12 K warmer than if this process was neglected. Hence, dynamical models should take this process in account across the whole mesospheric altitude range.

  19. High time resolution observations of the polar stratosphere and mesosphere using a ground-based 230-250 GHz microwave radiometer

    NASA Astrophysics Data System (ADS)

    Newnham, D. A.; Espy, P. J.; Clilverd, M. A.; Maxfield, D. J.; Hartogh, P.; Holmén, K.; Blindheim, S.; Horne, R. B.

    2012-04-01

    Microwave radiometry is used to measure thermal emission by the Doppler- and pressure-broadened molecular rotational lines of atmospheric gases, from which vertical abundance profiles can be determined. Since solar radiation is not required for the measurement, the technique has the advantage that continuous observations are possible including throughout the polar winter. We describe the development of a passive microwave radiometer [Espy, P. J., P. Hartogh, and K. Holmen (2006), Proc. SPIE, 6362, 63620P, doi:10.1117/12.688953] for ground-based remote sensing of the polar middle atmosphere. The instrument measures nitric oxide (NO), ozone (O3), and carbon monoxide (CO) vertical profiles over the altitude range 35-90 km with time resolution as high as 15 minutes, allowing the diurnal variability of trace chemical species to be investigated. Heterodyne detection of atmospheric emission at 230 GHz and 250 GHz (wavelength ~1.25 mm) with a receiver noise temperature of 300 K is achieved using a superconductor-insulator-superconductor (SIS) mixer cooled to 4 K. The down-converted signals at 1.35 GHz and 2.10 GHz are analysed using both a moderate-resolution (28 kHz, 220 MHz bandwidth) and a high-resolution (14 kHz, 40 MHz bandwidth) chirp-transform spectrometer (CTS). The instrument was operated semi-autonomously at Troll station (72° 01'S 02° 32'E, 1270 m above sea level), Antarctica during 2008-10 and at the Arctic LIDAR Observatory for Middle Atmosphere Research (ALOMAR, 69° 16'N, 16° 00'E, 380 m above sea level), northern Norway during 2011-12. NO volume mixing ratio (VMR) profiles have been inverted from calibrated brightness temperature spectra of the NO line centred at 250.796 GHz, observed above Troll station, using the Microwave Observation Line Estimation and Retrieval (MOLIERE) version 5 code. A priori pressure, temperature, ozone, water vapour, and NO profiles above 30 km were calculated using the Sodankylä Ion and Neutral Chemistry (SIC, version 6

  20. Spin-polarized neutron matter: Critical unpairing and BCS-BEC precursor

    NASA Astrophysics Data System (ADS)

    Stein, Martin; Sedrakian, Armen; Huang, Xu-Guang; Clark, John W.

    2016-01-01

    We obtain the critical magnetic field required for complete destruction of S -wave pairing in neutron matter, thereby setting limits on the pairing and superfluidity of neutrons in the crust and outer core of magnetars. We find that for fields B ≥1017 G the neutron fluid is nonsuperfluid—if weaker spin 1 superfluidity does not intervene—a result with profound consequences for the thermal, rotational, and oscillatory behavior of magnetars. Because the dineutron is not bound in vacuum, cold dilute neutron matter cannot exhibit a proper BCS-BEC crossover. Nevertheless, owing to the strongly resonant behavior of the n n interaction at low densities, neutron matter shows a precursor of the BEC state, as manifested in Cooper-pair correlation lengths being comparable to the interparticle distance. We make a systematic quantitative study of this type of BCS-BEC crossover in the presence of neutron fluid spin polarization induced by an ultrastrong magnetic field. We evaluate the Cooper-pair wave function, quasiparticle occupation numbers, and quasiparticle spectra for densities and temperatures spanning the BCS-BEC crossover region. The phase diagram of spin-polarized neutron matter is constructed and explored at different polarizations.

  1. Effects of polar and nonpolar groups on the solubility of organic compounds in soil organic matter

    USGS Publications Warehouse

    Chiou, C.T.; Kile, D.E.

    1994-01-01

    Vapor sorption capacities on a high-organic-content peat, a model for soil organic matter (SOM), were determined at room temperature for the following liquids: n-hexane, 1,4-dioxane, nitroethane, acetone, acetonitrile, 1-propanol, ethanol, and methanol. The linear organic vapor sorption is in keeping with the dominance of vapor partition in peat SOM. These data and similar results of carbon tetrachloride (CT), trichloroethylene (TCE), benzene, ethylene glycol monoethyl ether (EGME), and water on the same peat from earlier studies are used to evaluate the effect of polarity on the vapor partition in SOM. The extrapolated liquid solubility from the vapor isotherm increases sharply from 3-6 wt % for low-polarity liquids (hexane, CT, and benzene) to 62 wt % for polar methanol and correlates positively with the liquid's component solubility parameters for polar interaction (??P) and hydrogen bonding (??h). The same polarity effect may be expected to influence the relative solubilities of a variety of contaminants in SOM and, therefore, the relative deviations between the SOM-water partition coefficients (Kom) and corresponding octanol-water partition coefficients (Kow) for different classes of compounds. The large solubility disparity in SOM between polar and nonpolar solutes suggests that the accurate prediction of Kom from Kow or Sw (solute water solubility) would be limited to compounds of similar polarity.

  2. Ionization and NO production in the polar mesosphere during high-speed solar wind streams: model validation and comparison with NO enhancements observed by Odin-SMR

    NASA Astrophysics Data System (ADS)

    Kirkwood, S.; Osepian, A.; Belova, E.; Urban, J.; Perot, K.; Sinha, A. K.

    2015-05-01

    Precipitation of high-energy electrons (EEP) into the polar middle atmosphere is a potential source of significant production of odd nitrogen, which may play a role in stratospheric ozone destruction and in perturbing large-scale atmospheric circulation patterns. High-speed streams of solar wind (HSS) are a major source of energization and precipitation of electrons from the Earth's radiation belts, but it remains to be determined whether these electrons make a significant contribution to the odd-nitrogen budget in the middle atmosphere when compared to production by solar protons or by lower-energy (auroral) electrons at higher altitudes, with subsequent downward transport. Satellite observations of EEP are available, but their accuracy is not well established. Studies of the ionization of the atmosphere in response to EEP, in terms of cosmic-noise absorption (CNA), have indicated an unexplained seasonal variation in HSS-related effects and have suggested possible order-of-magnitude underestimates of the EEP fluxes by the satellite observations in some circumstances. Here we use a model of ionization by EEP coupled with an ion chemistry model to show that published average EEP fluxes, during HSS events, from satellite measurements (Meredith et al., 2011), are fully consistent with the published average CNA response (Kavanagh et al., 2012). The seasonal variation of CNA response can be explained by ion chemistry with no need for any seasonal variation in EEP. Average EEP fluxes are used to estimate production rate profiles of nitric oxide between 60 and 100 km heights over Antarctica for a series of unusually well separated HSS events in austral winter 2010. These are compared to observations of changes in nitric oxide during the events, made by the sub-millimetre microwave radiometer on the Odin spacecraft. The observations show strong increases of nitric oxide amounts between 75 and 90 km heights, at all latitudes poleward of 60° S, about 10 days after the

  3. The PHOCUS Project: Mesospheric Ice Particle Properties

    NASA Astrophysics Data System (ADS)

    Khaplanov, M.; Hedin, J.; Gumbel, J.

    2012-12-01

    On the morning of July 21, 2011, the PHOCUS sounding rocket was launched from Esrange, Sweden, intostrong noctilucent clouds (NLC) and polar mesosphere summer echoes (PMSE). The aim of the PHOCUS project (Particles, Hydrogen and Oxygen Chemistry in the Upper Summer mesosphere) is to study mesospheric particles (ice and meteoric smoke) and their interaction with their neutral and charged environment. Interactions of interest comprise the charging and nucleation of particles, the relationship between meteoric smoke and ice, and the influence of these particles on gas-phase chemistry. Here we will describe the optical measurements of the ice particlesand present first results including comparison to the other simultaneous measurements.Ice particle properties were probed with a set of three NLC photometers from Stockholm University. NLC photometry is currently the best technique available for determining altitude ranges of NLC in situ. At the same time, UV photometry allows a study of particle properties like size and shape by analysing the spectral dependence (colour ratio), angle dependence (phase function), and polarisation of the scattering. The set of NLC photometer flown on PHOCUS was a unique photometer package that for the first time investigated all three parameters simultaneously. Two forward-viewing photometers measured at different wavelengths (one in the UV at 220 nm and the other in the visible at 440 nm) and were both equipped with fixed linear polarisers. The payload spin was utilised to scan through the polarisation direction, thus providing us with the Stokes vectors I, Q and U at both wavelengths. The third photometer (also measured in the UV at 220 nm)was mounted sideways, viewing the overhead sky at an angle of 40°from the rocket spin axis. Due to the payload spin, the NLC was observed under varying scattering geometries as the payload approached the cloud layer. Thus, this set of NLC photometers provided a complete optical characterization of the

  4. Methanogenesis, Mesospheric Clouds, and Global Habitability

    NASA Technical Reports Server (NTRS)

    Pueschel, Rudolf F.; Condon, Estelle P. (Technical Monitor)

    2000-01-01

    Hyperthermophilic methanogens can exist in a deep hot biosphere up to 110 C, or 10 km deep. Methane (CH4) itself is thermodynamically stable to depths of 300 km. Geologic (microbial plus abiogenic thermal) methane is transported upward, attested to by its association with helium, to form petroleum pools. Near or at the surface, geologic CH4 mixes with other natural and with anthropogenic CH4 yielding annual emissions into the atmosphere of 500 Tg, of which 200 Tg are natural and 300 Tg are man-made. The atmospheric lifetime of CH4, a greenhouse gas 20 times more effective than CO2 in raising global temperatures, is approximately 10 years. It is removed from the atmosphere mainly by reactions with hydroxyl radical (OH) to form CO2, but also by dry soil and by conversion to H2O in the stratosphere and middle atmosphere. A sudden rise in atmospheric temperatures by 9-12 C some 55 million years ago has been explained by the release in a few thousand years of three trillion tons of CH4 out of 15 trillion tons that had formed beneath the sea floor. What prevented this CH4-induced greenhouse effect from running away? An analog to the CH4-burp of 55 million years ago is the CH4-doubling over the past century which resulted in a increase in upper level H2O from 4.3 ppmv to 6 ppmv. This 30% increase in H2O vapor yielded a tenfold increase in brightness of polar mesospheric clouds because of a strong dependence of the ice particle nucleation rate on the water saturation ratios. Models show that at a given temperature the optical depth of mesospheric clouds scales as [H2O]beta with beta varying between 4 and 8. Radiative transfer tools applied to mesospheric particles suggest that an optical depth of approximately one, or 1000 times the current mesospheric cloud optical depth, would result in tropospheric cooling of about 10 K. Assuming beta=6, a thousandfold increase in optical thickness would require a three-fold increase of H2O, or a 20-fold increase of CH4. At the current

  5. Methanogenesis, Mesospheric Clouds, and Global Habitability

    NASA Technical Reports Server (NTRS)

    Pueschel, Rudolf F.; Condon, Estelle P. (Technical Monitor)

    2000-01-01

    Hyperthermophilic methanogens can exist in a deep hot biosphere up to 110 C, or 10 km deep. Methane (CH4) itself is thermodynamically stable to depths of 300 km. Geologic (microbial plus abiogenic thermal) methane is transported upward, attested to by its association with helium, to form petroleum pools. Near or at the surface, geologic CH4 mixes with other natural and with anthropogenic CH4 yielding annual emissions into the atmosphere of 500 Tg, of which 200 Tg are natural and 300 Tg are man-made. The atmospheric lifetime of CH4, a greenhouse gas 20 times more effective than CO2 in raising global temperatures, is approximately 10 years. It is removed from the atmosphere mainly by reactions with hydroxyl radical (OH) to form CO2, but also by dry soil and by conversion to H2O in the stratosphere and middle atmosphere. A sudden rise in atmospheric temperatures by 9-12 C some 55 million years ago has been explained by the release in a few thousand years of three trillion tons of CH4 out of 15 trillion tons that had formed beneath the sea floor. What prevented this CH4-induced greenhouse effect from running away? An analog to the CH4-burp of 55 million years ago is the CH4-doubling over the past century which resulted in a increase in upper level H2O from 4.3 ppmv to 6 ppmv. This 30% increase in H2O vapor yielded a tenfold increase in brightness of polar mesospheric clouds because of a strong dependence of the ice particle nucleation rate on the water saturation ratios. Models show that at a given temperature the optical depth of mesospheric clouds scales as [H2O]beta with beta varying between 4 and 8. Radiative transfer tools applied to mesospheric particles suggest that an optical depth of approximately one, or 1000 times the current mesospheric cloud optical depth, would result in tropospheric cooling of about 10 K. Assuming beta=6, a thousandfold increase in optical thickness would require a three-fold increase of H2O, or a 20-fold increase of CH4. At the current

  6. HF radar observations of a quasi-biennial oscillation in midlatitude mesospheric winds

    NASA Astrophysics Data System (ADS)

    Malhotra, Garima; Ruohoniemi, J. M.; Baker, J. B. H.; Hibbins, R. E.; McWilliams, K. A.

    2016-11-01

    The equatorial quasi-biennial oscillation (QBO) is known to be an important source of interannual variability in the middle- and high-latitude stratosphere. The influence of the QBO on the stratospheric polar vortex in particular has been extensively studied. However, the impact of the QBO on the winds of the midlatitude mesosphere is much less clear. We have applied 13 years (2002-2014) of data from the Saskatoon Super Dual Auroral Radar Network HF radar to show that there is a strong QBO signature in the midlatitude mesospheric zonal winds during the late winter months. We find that the Saskatoon mesospheric winds are related to the winds of the equatorial QBO at 50 hPa such that the westerly mesospheric winds strengthen when QBO is easterly, and vice versa. We also consider the situation in the late winter Saskatoon stratosphere using the European Centre for Medium-Range Weather Forecasts ERA-Interim reanalysis data set. We find that the Saskatoon stratospheric winds between 7 hPa and 70 hPa weaken when the equatorial QBO at 50 hPa is easterly, and vice versa. We speculate that gravity wave filtering from the QBO-modulated stratospheric winds and subsequent opposite momentum deposition in the mesosphere plays a major role in the appearance of the QBO signature in the late winter Saskatoon mesospheric winds, thereby coupling the equatorial stratosphere and the midlatitude mesosphere.

  7. Antarctic Mesospheric Clouds Formed From Space Shuttle Exhaust

    DTIC Science & Technology

    2005-07-06

    Antarctica identify iron ablated from the shuttle’s main engines. Additional satellite observations of polar mesospheric clouds (PMCs) show a burst...evidence heretofore that a shuttle plume can reach Antarctica . Any significant global-scale impact to PMCs has therefore been unsupported by...ground-based lidar observations of both Fe and PMCs from Antarctica that show rapid inter-hemispheric transport of the plume and its arrival in

  8. Ice particulates in the mesosphere

    NASA Technical Reports Server (NTRS)

    Chesworth, E. T.; Hale, L. C.

    1974-01-01

    The observations of noctilucent clouds, the measurements of hydrated and of large immobile ions, and the light-scattering layer detected by the OGO-6 satellite suggest the presence of particulates, probably ice, in the mesosphere. The correlation between temperature and positive ion conductivity where the vapor pressure over ice becomes greater than atmospheric pressure in the stratopause region indicates the presence of ice crystals throughout the mesosphere over a wide range of latitudes during all seasons. Between one and ten billion ice crystals per cubic meter of order 10 nanometers in diameter can dominate ionization loss processes in the mesosphere, and can explain a variety of experimental observations, including observed solar angle dependence and seasonal variability of electron density.

  9. Attosecond nonlinear polarization and light-matter energy transfer in solids.

    PubMed

    Sommer, A; Bothschafter, E M; Sato, S A; Jakubeit, C; Latka, T; Razskazovskaya, O; Fattahi, H; Jobst, M; Schweinberger, W; Shirvanyan, V; Yakovlev, V S; Kienberger, R; Yabana, K; Karpowicz, N; Schultze, M; Krausz, F

    2016-06-02

    Electric-field-induced charge separation (polarization) is the most fundamental manifestation of the interaction of light with matter and a phenomenon of great technological relevance. Nonlinear optical polarization produces coherent radiation in spectral ranges inaccessible by lasers and constitutes the key to ultimate-speed signal manipulation. Terahertz techniques have provided experimental access to this important observable up to frequencies of several terahertz. Here we demonstrate that attosecond metrology extends the resolution to petahertz frequencies of visible light. Attosecond polarization spectroscopy allows measurement of the response of the electronic system of silica to strong (more than one volt per ångström) few-cycle optical (about 750 nanometres) fields. Our proof-of-concept study provides time-resolved insight into the attosecond nonlinear polarization and the light-matter energy transfer dynamics behind the optical Kerr effect and multi-photon absorption. Timing the nonlinear polarization relative to the driving laser electric field with sub-30-attosecond accuracy yields direct quantitative access to both the reversible and irreversible energy exchange between visible-infrared light and electrons. Quantitative determination of dissipation within a signal manipulation cycle of only a few femtoseconds duration (by measurement and ab initio calculation) reveals the feasibility of dielectric optical switching at clock rates above 100 terahertz. The observed sub-femtosecond rise of energy transfer from the field to the material (for a peak electric field strength exceeding 2.5 volts per ångström) in turn indicates the viability of petahertz-bandwidth metrology with a solid-state device.

  10. Attosecond nonlinear polarization and light-matter energy transfer in solids

    NASA Astrophysics Data System (ADS)

    Sommer, A.; Bothschafter, E. M.; Sato, S. A.; Jakubeit, C.; Latka, T.; Razskazovskaya, O.; Fattahi, H.; Jobst, M.; Schweinberger, W.; Shirvanyan, V.; Yakovlev, V. S.; Kienberger, R.; Yabana, K.; Karpowicz, N.; Schultze, M.; Krausz, F.

    2016-06-01

    Electric-field-induced charge separation (polarization) is the most fundamental manifestation of the interaction of light with matter and a phenomenon of great technological relevance. Nonlinear optical polarization produces coherent radiation in spectral ranges inaccessible by lasers and constitutes the key to ultimate-speed signal manipulation. Terahertz techniques have provided experimental access to this important observable up to frequencies of several terahertz. Here we demonstrate that attosecond metrology extends the resolution to petahertz frequencies of visible light. Attosecond polarization spectroscopy allows measurement of the response of the electronic system of silica to strong (more than one volt per ångström) few-cycle optical (about 750 nanometres) fields. Our proof-of-concept study provides time-resolved insight into the attosecond nonlinear polarization and the light-matter energy transfer dynamics behind the optical Kerr effect and multi-photon absorption. Timing the nonlinear polarization relative to the driving laser electric field with sub-30-attosecond accuracy yields direct quantitative access to both the reversible and irreversible energy exchange between visible-infrared light and electrons. Quantitative determination of dissipation within a signal manipulation cycle of only a few femtoseconds duration (by measurement and ab initio calculation) reveals the feasibility of dielectric optical switching at clock rates above 100 terahertz. The observed sub-femtosecond rise of energy transfer from the field to the material (for a peak electric field strength exceeding 2.5 volts per ångström) in turn indicates the viability of petahertz-bandwidth metrology with a solid-state device.

  11. Temperature trends in the mesosphere

    NASA Astrophysics Data System (ADS)

    Lübken, Franz-Josef; Berger, Uwe

    2013-04-01

    We have performed trend studies in the mesosphere in the period 1961-2009 with LIMA (Leibniz-Institute Middle Atmosphere model) which is based on ECMWF below approximately 40 km and adapts temporal variations of CO2 and O3 according to observations. There is general agreement between LIMA and observations. Temperatures in the mesosphere/lower thermosphere vary non-uniformly with time, mainly due to the influence of ozone. We have therefore separated the influence of CO2(t) and O3(t) when determining trends. It is important to distinguish between trends on pressure altitudes, zp, and geometric altitudes, zgeo, where the latter includes the effect of shrinking due to cooling at lower heights. Maximum total temperature trends reach approximately -1,3 K/dec at zp ~60 km and -1.8 K/dec at zgeo ~70 km, respectively. Carbon dioxide is the main driver of these trends in the mesosphere, whereas ozone contributes approximately one third, both on geometric and pressure heights. Depending on the time period chosen, the ozone effect on trends can be significantly smaller or larger. Temperature trends on geometric and pressure altitudes can differ by as much as -0.9 K/dec in the mesosphere. The altitudes of pressure levels in the mesosphere decrease up to several hundred meters. The shift maximizes at mesopause levels where it accumulates to more than 1 km. Most of the shrinking occurs in the mesosphere and a smaller fraction (~20%) in the stratosphere. For the first time, we have performed long term runs with LIMA applying the 20th Century Reanalysis from NCEP/NCAR dating back to 1871. Again, trends are non-uniform with time. Since the late 19th century temperatures in the mesosphere have dropped by approximately 5-7 K on pressure altitudes, and up to 10-12 K on geometric altitudes. This is much more then typical trends in the troposphere and stratosphere. It is therefore justified to summarize that the mesosphere (at least in summer and at middle latitudes) reacts

  12. Inertio Gravity Waves in the Upper Mesosphere

    NASA Technical Reports Server (NTRS)

    Mayr, H. G.; Mengel, J. G.; Talaat, E. L.; Porter, H. S.; Chan, K. L.

    2003-01-01

    In the polar region of the upper mesosphere, horizontal wind oscillations have been observed with periods around 10 hours (Hernandez et al., 1992). Such waves are generated in our Numerical Spectral Model (NSM) and appear to be inertio gravity waves (IGW). Like the planetary waves (PW) in the model, the IGWs are generated by instabilities that arise in the mean zonal circulation. In addition to stationary waves for m = 0, eastward and westward propagating waves for m = 1 to 4 appear above 70 km that grow in magnitude up to about 110 km, having periods between 9 and 11 hours. The m = 1 westward propagating IGWs have the largest amplitudes, which can reach at the poles 30 m/s. Like PWs, the IGWs are intermittent but reveal systematic seasonal variations, with the largest amplitudes occurring generally in winter and spring. The IGWs propagate upward with a vertical wavelength of about 20 km.

  13. Spatial Heterodyne Imager for Mesospheric Radicals on STPSat-1

    NASA Astrophysics Data System (ADS)

    Englert, Christoph R.; Stevens, Michael H.; Siskind, David E.; Harlander, John M.; Roesler, Frederick L.

    2010-10-01

    The Spatial Heterodyne Imager for Mesospheric Radicals (SHIMMER) was a high-resolution, near ultraviolet spectrometer that imaged the Earth's limb for 2.5 years between March 2007 and October 2009. The instrument used the Spatial Heterodyne Spectroscopy technique for the first time on a satellite and successfully demonstrated its capabilities. SHIMMER measured the solar resonance fluorescence of the OH A2Σ+-X2Π (0, 0) band around 309 nm, which allows the retrieval of mesospheric OH density profiles. It also measured the Rayleigh scattered background from the clear atmosphere and solar scattering from polar mesospheric cloud particles. We present details on the SHIMMER mission, the payload design, and the data analysis. A comparison between SHIMMER and concurrent Microwave Limb Sounder OH data shows good agreement between 60 and 90 km altitude for several latitudes and seasons. We also find good agreement of the SHIMMER OH densities and standard photochemical model calculations between 60 and 80 km. We find no evidence of a 25%-35% mesospheric OH deficit, previously reported using Middle Atmosphere High-Resolution Spectrograph Investigation (MAHRSI) OH data. However, independent analysis of Rayleigh scattered background signals observed by SHIMMER and MAHRSI under similar lighting conditions revealed that MAHRSI radiances are systematically smaller than SHIMMER radiances by 24%. Although this difference is well outside of the combined uncertainties for both experiments, the agreement of SHIMMER OH with Microwave Limb Sounder OH and standard photochemistry results, together with our Rayleigh scattering comparison, suggests an unidentified MAHRSI calibration problem that effectively eliminates the mesospheric OH deficit reported using MAHRSI observations.

  14. Spin polarization in high density quark matter under a strong external magnetic field

    NASA Astrophysics Data System (ADS)

    Tsue, Yasuhiko; da Providência, João; Providência, Constança; Yamamura, Masatoshi; Bohr, Henrik

    In high density quark matter under a strong external magnetic field, possible phases are investigated by using the two-flavor Nambu-Jona-Lasinio (NJL) model with tensor-type four-point interaction between quarks, as well as the axial-vector-type four-point interaction. In the tensor-type interaction under the strong external magnetic field, it is shown that a quark spin polarized phase is realized in all regions of the quark chemical potential under consideration within the lowest Landau level approximation. In the axial-vector-type interaction, it is also shown that the quark spin polarized phase appears in the wide range of the quark chemical potential. In both the interactions, the quark mass in zero and small chemical potential regions increases which indicates that the chiral symmetry breaking is enhanced, namely the magnetic catalysis occurs.

  15. Stabilization of polar soils organic matter: insights from 13-C NMR and ESR spectroscopy

    NASA Astrophysics Data System (ADS)

    Abakumov, Evgeny

    2017-04-01

    Polar soils play a key role in the global carbon balance, as they contain maximum stocks of soil organic matter (SOM) within the whole pedosphere. Low temperature and severe conditions provides the accumulation of large amounts of organic matter in permafrost soils over thousands of years. The quality and composition of organic matter of polar soils is underestimated. In order to better understand the implication of permafrost SOM to greenhouse gas emissions, an accurate knowledge of its spatial distribution, both in terms of quantity and quality (i.e. biodegradability, chemical composition and humification degree) is needed. The chemical composition of SOM determines its decomposability and, therefore, it determines the rate at which carbon may be transferred from soils to the atmosphere under warming conditions. Biodegradability of SOM has been related to humification degree, as more advanced stages in the humification process imply a depletion of the labile molecules, as well as an increase in the bulk aromaticity, which provides a higher stability of the SOM. Soils from Antarctic and different sectors of Arctic biome were investigated by 13-C NMR and electron spin resonance spectroscopy. It was shown, that the characteristic feature of polar soils humic acids is the dominance of aliphatic compounds on the aromatic one. This is related to the humification precursors component composition, namely to dominance of the remnants of lower plants, especially in Antarctic and low period of biological activity, which regulates the humification rate. Humic acids of Antarctic and various Arctic soils show the portion of aromatic components not more than 30 %. ESR spectroscopy shown that the concentration of free radicals is proportional to the humic acids stabilization degree. Less humified organic materials show the highest portion of free radical content, while the most developed soils and buried organic layers show decreased contents of free radicals. The database on

  16. Model of dark matter and dark energy based on gravitational polarization

    SciTech Connect

    Blanchet, Luc; Le Tiec, Alexandre

    2008-07-15

    A model of dark matter and dark energy based on the concept of gravitational polarization is investigated. We propose an action in standard general relativity for describing, at some effective or phenomenological level, the dynamics of a dipolar medium, i.e. one endowed with a dipole moment vector, and polarizable in a gravitational field. Using first-order cosmological perturbations, we show that the dipolar fluid is undistinguishable from standard dark energy (a cosmological constant {lambda}) plus standard dark matter (a pressureless perfect fluid), and therefore benefits from the successes of the {lambda}-cold-dark-matter scenario at cosmological scales. Invoking an argument of 'weak clusterization' of the mass distribution of dipole moments, we find that the dipolar dark matter reproduces the phenomenology of the modified Newtonian dynamics at galactic scales. The dipolar medium action naturally contains a cosmological constant, and we show that if the model is to come from some fundamental underlying physics, the cosmological constant {lambda} should be of the order of a{sub 0}{sup 2}/c{sup 4}, where a{sub 0} denotes the modified Newtonian dynamics constant acceleration scale, in good agreement with observations.

  17. Antimatter and Dark Matter Search in Space: BESS-Polar Results

    NASA Technical Reports Server (NTRS)

    Mitchell, John W.; Yamamoto, Akira

    2009-01-01

    The apex of the Balloon-borne Experiment with a Superconducting Spectrometer program was reached with the Antarctic flight of BESS-Polar II, during the 2007-2008 Austral Summer, that obtained 24.5 days of data on over 4.7 billion cosmic-ray events. The US-Japan BESS Collaboration uses elementary particle measurements to study the early Universe and provides fundamental data on the spectra of light cosmic-ray elements and isotopes. BESS measures the energy spectra of cosmic-ray antiprotons to investigate signatures of possible exotic sources, such as dark-matter candidates, and searches for heavier anti-nuclei that might reach Earth from antimatter domains formed during symmetry breaking processes in the early Universe. Since 1993, BESS has carried out eleven high-latitude balloon flights, two of long duration, that together have defined the study of antiprotons below about 4 GeV, provided standard references for light element and isotope spectra, and set the most sensitive limits on the existence of anti-deuterons and anti-helium, The BESS-Polar II flight took place at Solar Minimum, when the sensitivity of the low-energy antiproton measurements to a primary source is greatest. The rich BESS-Polar II dataset more than doubles the combined data from all earlier BESS flights and has 10-20 times the statistics of BESS data from the previous Solar Minimum. Here, we summarize the scientific results of BESS program, focusing on the results obtained using data from the long-duration flights of BESS-Polar I (2004) and BESS-Polar II.

  18. Antimatter and Dark Matter Search in Space: BESS-Polar Results

    NASA Technical Reports Server (NTRS)

    Mitchell, John W.; Yamamoto, Akira

    2009-01-01

    The apex of the Balloon-borne Experiment with a Superconducting Spectrometer program was reached with the Antarctic flight of BESS-Polar II, during the 2007-2008 Austral Summer, that obtained 24.5 days of data on over 4.7 billion cosmic-ray events. The US-Japan BESS Collaboration uses elementary particle measurements to study the early Universe and provides fundamental data on the spectra of light cosmic-ray elements and isotopes. BESS measures the energy spectra of cosmic-ray antiprotons to investigate signatures of possible exotic sources, such as dark-matter candidates, and searches for heavier anti-nuclei that might reach Earth from antimatter domains formed during symmetry breaking processes in the early Universe. Since 1993, BESS has carried out eleven high-latitude balloon flights, two of long duration, that together have defined the study of antiprotons below about 4 GeV, provided standard references for light element and isotope spectra, and set the most sensitive limits on the existence of anti-deuterons and anti-helium, The BESS-Polar II flight took place at Solar Minimum, when the sensitivity of the low-energy antiproton measurements to a primary source is greatest. The rich BESS-Polar II dataset more than doubles the combined data from all earlier BESS flights and has 10-20 times the statistics of BESS data from the previous Solar Minimum. Here, we summarize the scientific results of BESS program, focusing on the results obtained using data from the long-duration flights of BESS-Polar I (2004) and BESS-Polar II.

  19. Charging of mesospheric particles - Implications for electron density and particle coagulation

    NASA Technical Reports Server (NTRS)

    Jensen, Eric J.; Thomas, Gary E.

    1991-01-01

    The relationship between N(e) and mesospheric aerosols near the mesopause is studied. The full distribution of charges on mesospheric aerosols is calculated, including dust and ice particles with radii ranging from 1 to 400 nm. The N(e) and ion density N(i) are obtained and ionization height profiles are calculated. The effects of dust and ice particles on N(e) and N(i) are studied for a wide range of assumed conditions. The results indicate that aerosol concentrations associated with visible polar mesospheric clouds are unlikely to cause a severe N(e) depletion. The pronounced 'bite-out' of N(e) at about 87 km in the summertime may be caused by a large concentration of small ice particles in a narrow cold layer near the mesosphere. Net negative charge on mesospheric aerosols may severely inihibit coagulation, so that mesospheric dust would not grow significantly. A higher supersaturation with respect to water vapor would be needed for heterogeneous nucleation of ice crystals.

  20. Automatic identification of gray and white matter components in polarized light imaging.

    PubMed

    Dammers, Jürgen; Breuer, Lukas; Axer, Markus; Kleiner, Melanie; Eiben, Björn; Grässel, David; Dickscheid, Timo; Zilles, Karl; Amunts, Katrin; Shah, N Joni; Pietrzyk, Uwe

    2012-01-16

    Polarized light imaging (PLI) enables the visualization of fiber tracts with high spatial resolution in microtome sections of postmortem brains. Vectors of the fiber orientation defined by inclination and direction angles can directly be derived from the optical signals employed by PLI analysis. The polarization state of light propagating through a rotating polarimeter is varied in such a way that the detected signal of each spatial unit describes a sinusoidal signal. Noise, light scatter and filter inhomogeneities, however, interfere with the original sinusoidal PLI signals, which in turn have direct impact on the accuracy of subsequent fiber tracking. Recently we showed that the primary sinusoidal signals can effectively be restored after noise and artifact rejection utilizing independent component analysis (ICA). In particular, regions with weak intensities are greatly enhanced after ICA based artifact rejection and signal restoration. Here, we propose a user independent way of identifying the components of interest after decomposition; i.e., components that are related to gray and white matter. Depending on the size of the postmortem brain and the section thickness, the number of independent component maps can easily be in the range of a few ten thousand components for one brain. Therefore, we developed an automatic and, more importantly, user independent way of extracting the signal of interest. The automatic identification of gray and white matter components is based on the evaluation of the statistical properties of the so-called feature vectors of each individual component map, which, in the ideal case, shows a sinusoidal waveform. Our method enables large-scale analysis (i.e., the analysis of thousands of whole brain sections) of nerve fiber orientations in the human brain using polarized light imaging.

  1. Solar mesosphere explorer: Experiment description

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The Solar Mesosphere Explorer (SME) satellite experiments will provide a comprehensive study of atmospheric ozone and the processes which form and destroy it. Five instruments to be carried on the spacecraft will measure the ozone density and altitude distribution, monitor the incoming solar radiation, and measure other atmospheric constituents which affect ozone. The investigative approach concept, methods and procedures, preflight studies, and orbits and mission lifetime are presented. Descriptions of the instruments are also presented.

  2. Is the vast polar structure of dwarf galaxies a serious problem for Λ cold dark matter?

    NASA Astrophysics Data System (ADS)

    Lipnicky, Andrew; Chakrabarti, Sukanya

    2017-06-01

    The dwarf galaxies around the Milky Way are distributed in a so-called vast polar structure (VPOS) that may be in conflict with Λ cold dark matter (ΛCDM) simulations. Here, we seek to determine if the VPOS poses a serious challenge to the ΛCDM paradigm on galactic scales. Specifically, we investigate if the VPOS remains coherent as a function of time. Using the measured Hubble Space Telescope (HST) proper motions and associated uncertainties, we integrate the orbits of the classical Milky Way satellites backwards in time and find that the structure disperses well before a dynamical time. We also examine, in particular, Leo I and Leo II using their most recent proper motion data, both of which have extreme kinematic properties, but these satellites do not appear to drive the polar fit that is seen at the present day. We have studied the effect of the uncertainties on the HST proper motions on the coherence of the VPOS as a function of time. We find that 8 of the 11 classical dwarfs have reliable proper motions; for these eight, the VPOS also loses significance in less than a dynamical time, indicating that the VPOS is not a dynamically stable structure. Obtaining more accurate proper motion measurements of Ursa Minor, Sculptor and Carina would bolster these conclusions.

  3. Cisplatin loaded albumin mesospheres for lung cancer treatment

    PubMed Central

    Lee, Hung-Yen; Mohammed, Kamal A; Goldberg, Eugene P; Kaye, Frederic; Nasreen, Najmunnisa

    2015-01-01

    The low solubility of cisplatin in aqueous solution limits the treatment effectiveness and the application of cisplatin in various kinds of drug-eluting devices. Although cisplatin has a high solubility in Dimethyl sulfoxide (DMSO), the toxicity of cisplatin can be greatly reduced while dissolved in DMSO. In this study, the solid powder of cisplatin-loaded albumin mesospheres (CDDP/DMSO-AMS), in a size range of 1 to 10 µm, were post-loaded with cisplatin and showed high cisplatin content (16% w/w) and effective cytotoxicity to lung cancer cells. Cisplatin were efficiently absorbed into the albumin mesospheres (AMS) in DMSO and, most importantly, the toxicity of cisplatin was remained at 100% after the loading process. This CDDP/DMSO-AMS was designed for the intratumoral injection through the bronchoscopic catheter or dry powder inhalation (DPI) due to its high stability in air or in solution. This CDDP/DMSO-AMS showed a fast cisplatin release within 24 hours. In the in vitro study, CDDP/DMSO-AMS showed high effectiveness on killing the lung cancer cells including the non-small cell lung cancer (NCL-H23 and A549), malignant mesothelioma (CRL-2081) and the mouse lung carcinoma (Lewis lung carcinoma) cell lines. The albumin based mesospheres provide an ideal loading matrix for cisplatin and other metal-based drugs due to the high swelling degree and fast uptake rate in the organic solvents with high polarity. In addition, to investigate the effects of polysaccharides, such as chitosan and chondroitin, on enhancing loading efficiency and lasting cytotoxicity of cisplatin, the polysaccharide-modified albumin mesospheres were synthesized and loaded with cisplatin in this study. PMID:25973300

  4. Evaluating fibre orientation dispersion in white matter: Comparison of diffusion MRI, histology and polarized light imaging.

    PubMed

    Mollink, Jeroen; Kleinnijenhuis, Michiel; Cappellen van Walsum, Anne-Marie van; Sotiropoulos, Stamatios N; Cottaar, Michiel; Mirfin, Christopher; Heinrich, Mattias P; Jenkinson, Mark; Pallebage-Gamarallage, Menuka; Ansorge, Olaf; Jbabdi, Saad; Miller, Karla L

    2017-08-15

    Diffusion MRI is an exquisitely sensitive probe of tissue microstructure, and is currently the only non-invasive measure of the brain's fibre architecture. As this technique becomes more sophisticated and microstructurally informative, there is increasing value in comparing diffusion MRI with microscopic imaging in the same tissue samples. This study compared estimates of fibre orientation dispersion in white matter derived from diffusion MRI to reference measures of dispersion obtained from polarized light imaging and histology. Three post-mortem brain specimens were scanned with diffusion MRI and analyzed with a two-compartment dispersion model. The specimens were then sectioned for microscopy, including polarized light imaging estimates of fibre orientation and histological quantitative estimates of myelin and astrocytes. Dispersion estimates were correlated on region - and voxel-wise levels in the corpus callosum, the centrum semiovale and the corticospinal tract. The region-wise analysis yielded correlation coefficients of r = 0.79 for the diffusion MRI and histology comparison, while r = 0.60 was reported for the comparison with polarized light imaging. In the corpus callosum, we observed a pattern of higher dispersion at the midline compared to its lateral aspects. This pattern was present in all modalities and the dispersion profiles from microscopy and diffusion MRI were highly correlated. The astrocytes appeared to have minor contribution to dispersion observed with diffusion MRI. These results demonstrate that fibre orientation dispersion estimates from diffusion MRI represents the tissue architecture well. Dispersion models might be improved by more faithfully incorporating an informed mapping based on microscopy data. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  5. Impacts of Polar Changes on the UV-induced Mineralization of Terrigenous Dissolved Organic Matter.

    PubMed

    Sulzberger, Barbara; Arey, J Samuel

    2016-07-05

    Local climates in the Northern and Southern Hemisphere are influenced by Arctic Amplification and by interactions of the Antarctic ozone hole with climate change, respectively. Polar changes may affect hydroclimatic conditions in temperate regions, for example, by increasing the length and intensity of precipitation events at Northern Hemisphere midlatitudes. Additionally, global warming has led to the thawing of ancient permafrost soils, particularly in Arctic regions, due to Arctic Amplification. Both heavy precipitation events and thawing of permafrost are increasing the net transfer of terrestrially derived dissolved organic matter (DOM) from land to surface waters. In aquatic ecosystems, UV-induced oxidation of terrigenous DOM (tDOM) produces atmospheric CO2 and this process is one of several mechanisms by which natural organic matter in aquatic and soil environments may play an important role in climate feedbacks. The Arctic is particularly affected by these processes: for example, melting of Arctic sea ice allows solar UV radiation to penetrate into the ice-free Arctic Ocean and to cause photochemical reactions that result in bleaching and mineralization of tDOM. Open questions, in addition to those shown in the Graphical Abstract, remain regarding the resulting contributions of tDOM photomineralization to CO2 production and global warming.

  6. Diurnal variation of mesospheric ozone

    NASA Astrophysics Data System (ADS)

    Vaughan, G.

    1982-03-01

    Four Petrel rockets were flown from South Uist on October 2, 1979, to investigate the ozone concentration variation predicted by photochemical models between day and night in the mesosphere by means of interference filters that defined an approximately 10 nm bandwidth. The first two rockets contained photometers with wavebands centered at 265 and 290 nm, while the last two employed a single waveband at 265 nm. Results show significant diurnal variation above 54 km, which exceeds a factor of 2 above 65 km and reaches a factor of 10 between night and sunrise at 90 km.

  7. Missing driver in the Sun–Earth connection from energetic electron precipitation impacts mesospheric ozone

    PubMed Central

    Andersson, M. E.; Verronen, P. T.; Rodger, C. J.; Clilverd, M. A.; Seppälä, A.

    2014-01-01

    Energetic electron precipitation (EEP) from the Earth’s outer radiation belt continuously affects the chemical composition of the polar mesosphere. EEP can contribute to catalytic ozone loss in the mesosphere through ionization and enhanced production of odd hydrogen. However, the long-term mesospheric ozone variability caused by EEP has not been quantified or confirmed to date. Here we show, using observations from three different satellite instruments, that EEP events strongly affect ozone at 60–80 km, leading to extremely large (up to 90%) short-term ozone depletion. This impact is comparable to that of large, but much less frequent, solar proton events. On solar cycle timescales, we find that EEP causes ozone variations of up to 34% at 70–80 km. With such a magnitude, it is reasonable to suspect that EEP could be an important part of solar influence on the atmosphere and climate system. PMID:25312693

  8. Analysis of Trends at Mesospheric Heights in the Northern Hemisphere during 1961-2013

    NASA Astrophysics Data System (ADS)

    Berger, Uwe; Baumgarten, Gerd; Luebken, Franz Josef

    2016-04-01

    We have performed trend studies in the mesosphere in the period 1961-2013 with Leibniz-Institute Middle Atmosphere (LIMA) model driven by European Centre for Medium-Range Weather Forecasts reanalysis (ERA-interim) below approximately 45 km. LIMA adapts temporal variations of CO2 and O3 according to observations, and observed daily Lyman alpha fluxes. The simulation of the thermal state at the summer upper mesosphere allows to investigate the impact on the morphology of ice particle related phenomena such as polar mesosphere clouds (PMC). The PMC characteristics deduced from LIMA are validated with various data sets from satellite (NOAA-SBUV, AIM-SOFIE) observations. Generally good agreement is found between the modeled long-term PMC variations and that derived from SBUV observations. We investigate the role of trends in mesospheric water vapor and temperature that mainly force PMC trends. We show that water vapor and temperatures in the stratosphere/meso- sphere/lower thermosphere vary none-uniformly with time. Especially, we analyze the contribution of varying concentrations of CO2 and O3 to the temperature trend in the mesosphere. It is important to distinguish between trends on pressure altitudes and geometrical altitudes, where the latter includes the effect of shrinking due to cooling at lower heights. As a highlight, we will present first results in analyzing the very first appearance of NLC in 1885 observed after the volcanic eruption of Krakatao in August 1883 that injected a tremendous mass of water vapor into the stratosphere.

  9. Mesospheric Dynamical Changes Induced by the Solar Proton Events in October-November 2003

    NASA Technical Reports Server (NTRS)

    Jackman, Charles H.; Roble, Raymond G.; Fleming, Eric L.

    2007-01-01

    The very large solar storms in October-November 2003 caused solar proton events (SPEs) at the Earth that impacted the upper atmospheric polar cap regions. The Thermosphere Ionosphere Mesosphere Electrodynamic General Circulation Model (TIME-GCM) was used to study the atmospheric dynamical influence of the solar protons that occurred in Oct-Nov 2003, the fourth largest period of SPEs measured in the past 40 years. The highly energetic solar protons caused ionization, as well as dissociation processes, and ultimately produced odd hydrogen (HOx) and odd nitrogen (NOy). Significant short-lived ozone decreases (10-70%) followed these enhancements of HOx and NOy and led to a cooling of most of the lower mesosphere. This cooling caused an atmospheric circulation change that led to adiabatic heating of the upper mesosphere. Temperature changes up to plus or minus 2.6 K were computed as well as wind (zonal, meridional, vertical) perturbations up to 20-25% of the background winds as a result of 22 the solar protons. The solar proton-induced mesospheric temperature and wind perturbations diminished over a period of 4-6 weeks after the SPEs. The Joule heating in the mesosphere, induced by the solar protons, was computed to be relatively insignificant for these solar storms with most of the temperature and circulation perturbations caused by ozone depletion in the sunlit hemisphere.

  10. Exposure to atmospheric particulate matter enhances Th17 polarization through the aryl hydrocarbon receptor.

    PubMed

    van Voorhis, Michael; Knopp, Samantha; Julliard, Walker; Fechner, John H; Zhang, Xiaoji; Schauer, James J; Mezrich, Joshua D

    2013-01-01

    Lung diseases, including asthma, COPD, and other autoimmune lung pathologies are aggravated by exposure to particulate matter (PM) found in air pollution. IL-17 has been shown to exacerbate airway disease in animal models. As PM is known to contain aryl hydrocarbon receptor (AHR) ligands and the AHR has recently been shown to play a role in differentiation of Th17 T cells, the aim of this study was to determine whether exposure to PM could impact Th17 polarization in an AHR-dependent manner. This study used both cell culture techniques and in vivo exposure in mice to examine the response of T cells to PM. Initially experiments were conducted with urban dust particles from a standard reference material, and ultimately repeated with freshly collected samples of diesel exhaust and cigarette smoke. The readout for the assays was increased T cell differentiation as indicated by increased generation of IL-17A in culture, and increased populations of IL-17 producing cells by intracellular flow cytometry. The data illustrate that Th17 polarization was significantly enhanced by addition of urban dust in a dose dependent fashion in cultures of wild-type but not AHR(-/-) mice. The data further suggest that polycyclic aromatic hydrocarbons played a primary role in this enhancement. There was both an increase of Th17 cell differentiation, and also an increase in the amount of IL-17 secreted by the cells. In summary, this paper identifies a novel mechanism whereby PM can directly act on the AHR in T cells, leading to enhanced Th17 differentiation. Further understanding of the molecular mechanisms responsible for pathologic Th17 differentiation and autoimmunity seen after exposure to pollution will allow direct targeting of proteins involved in AHR activation and function for treatment of PM exposures.

  11. Characteristics of mesosphere echoes over Antarctica obtained using PANSY and MF radars

    NASA Astrophysics Data System (ADS)

    Tsutsumi, Masaki; Nakamura, Takuji; Sato, Toru; Nishimura, Koji; Sato, Kaoru; Tomikawa, Yoshihiro; Kohma, Masashi

    2016-07-01

    In the polar region characteristic radar echoes are observed from the mesosphere by using a VHF system. The nature of the echoes is distinctively different between summer and winter and those echoes are called Polar Mesosphere Summer Echoes (PMSEs) and Polar Mesosphere Winter Echoes (PMWEs), respectively. Since the PMSEs are usually very strong and can be easily measured with a small radar system, their nature is relatively well understood. On the other hand PMWEs are much weaker and they are still only poorly understood. The PANSY radar (47MHz) at Syowa station (69S) is the only large aperture atmospheric radar in the Antarctic, and can continuously survey the dynamics of the middle atmosphere with high time and height resolutions [Sato et al., 2014]. Nishiyama et al [2014] reported the first study of PMWEs using PANSY radar and showed a seasonal and local time dependence of these echoes. An MF radar system (2.4MHz) is co-located at Syowa, and has been operating for mesosphere and lower thermosphere observations. Although the MF radar has only a much poorer height resolution and is incapable of vertical wind measurement, it can almost continuously measure mesosphere day and night. In this study the nature of the mesosphere echoes, mainly PMWEs, are being studied using the two radars based on the observation made in 2015. These radars are operated using largely different radio frequencies and can provide complementary information with each other such as wind velocities and also echo scattering mechanisms. Horizontal wind velocities have been compared between the two radars with a great care mostly in the MF radar winds in order to avoid possible biases inherent in the correlation analysis technique employed for the MF radar wind measurement. A careful analysis has shown that the horizontal wind velocities agree well between the two systems with a high correlation coefficient around 0.8 throughout the height region of 65-85km. Aspect sensitivities estimated using

  12. Numerical modeling of mesospheric bores

    NASA Astrophysics Data System (ADS)

    Laughman, Brian Joseph

    Mesospheric bores were first observed in 1993 and since then there have been few efforts to characterize them. Early results invoked weakly nonlinear hydraulic theory to explain these observed bores and numerical results have reproduced the essential nonlinearities of bore evolution. Internal bores have been demonstrated to exist in density stratified fluids, such as the oceanic thermocline and tropospheric inversion layers, and have been approximated by the Benjamin-Davis-Ono (BDO) equation (the KdV analogue for internal waves). This thesis considers these earlier theories and explores the limits of their validity with two numerical models. The first is a one-dimensional solver of the KdV and BDO equations. The second model describes the nonlinear incompressible dynamics of the Navier-Stokes equations for thermal ducting environments. The results of both models are directly compared to constrain the validity of the weakly nonlinear theory. These results are also compared with spatial and velocity scales of airglow observations and demonstrate the viability of simple mesopausal thermal ducting environments to support realistic bore evolution. Based on observations and on the dependence of the dispersion relationship on the mean horizontal wind, Doppler ducting structures are posed and also demonstrate nonlinear bore evolution. The direction of future studies is then discussed, including extensions to more complex and realistic ducting environments characteristic of the mesosphere and lower thermosphere (MLT), the viability of forcing mechanisms beyond the long wave perturbations considered in these studies, and applications to observed bore events.

  13. Solar Mesosphere Explorer observations of stratospheric and mesospheric water vapor

    NASA Astrophysics Data System (ADS)

    Jakosky, Bruce M.; Thomas, Gary E.; Rusch, David W.; Barth, Charles A.; Lawrence, George M.; Olivero, John J.; Clancy, R. Todd; Sanders, Ryan W.; Knapp, Barry G.

    It is noted that while the SME (Solar Mesosphere Explorer) data is consistent with the earlier LIMS (Limb Infrared Monitor of the Stratosphere) results, its interpretation is complicated by aerosol contamination, particularly at altitudes below 35 km. This contamination arose from several volcanic eruptions, including that of El Chichon. Analyses are reported of a subset of data from the SME satellite, concentrating primarily on the period January through March 1982 so as to avoid contamination from the El Chichon volcanic aerosol. The SME observations of water vapor between 20 and 60 km were inverted for the first three months of 1982 as well as for selected additional periods. Reasonable results are obtained at locations where no contamination by aerosol is suspected.

  14. Mesosphere-Stratosphere Coupling: Implications for Climate Variability and Trends

    NASA Technical Reports Server (NTRS)

    Baldwin, Mark P.

    2004-01-01

    A key aspect of this project is the establishment of a causal link from circulation anomalies in the lower mesosphere and stratopause region downward through the stratosphere to the troposphere. The observational link for stratospheric sudden warmings and surface climate is fairly clear. However, our understanding of the dynamics is incomplete. We have been making significant progress in the area of dynamical mechanisms by which circulation anomalies in the stratosphere affect the troposphere. We are trying to understand the details and sequence of events that occur when a middle atmosphere (wind) anomaly propagates downward to near the tropopause. The wind anomaly could be caused by a warming or solar variations in the low-latitude stratopause region, or could have other causes. The observations show a picture that is consistent with a circulation anomaly that descends to the tropopause region, and can be detected as low as the mid-troposphere. Processes near the stratopause in the tropics appear to be important precursors to the wintertime development of the northern polar vortex. This may affect significantly our understanding of the process by which low-latitude wind anomalies in the low mesosphere and upper stratosphere evolve through the winter and affect the polar vortex.

  15. Spin-orbit-induced photoelectron spin polarization in angle-resolved photoemission from both atomic and condensed matter targets.

    PubMed

    Heinzmann, Ulrich; Dil, J Hugo

    2012-05-02

    The existence of highly spin polarized photoelectrons emitted from non-magnetic solids as well as from unpolarized atoms and molecules has been found to be very common in many studies over the past 40 years. This so-called Fano effect is based upon the influence of the spin-orbit interaction in the photoionization or the photoemission process. In a non-angle-resolved photoemission experiment, circularly polarized radiation has to be used to create spin polarized photoelectrons, while in angle-resolved photoemission even unpolarized or linearly polarized radiation is sufficient to get a high spin polarization. In past years the Rashba effect has become very important in the angle-resolved photoemission of solid surfaces, also with an observed high photoelectron spin polarization. It is the purpose of the present topical review to cross-compare the spin polarization experimentally found in angle-resolved photoelectron emission spectroscopy of condensed matter with that of free atoms, to compare it with the Rashba effect and topological insulators to describe the influence and the importance of the spin-orbit interaction and to show and disentangle the matrix element and phase shift effects therein.The relationship between the energy dispersion of these phase shifts and the emission delay of photoelectron emission in attosecond-resolved photoemission is also discussed. Furthermore the influence of chiral structures of the photo-effect target on the spin polarization, the interferences of different spin components in coherent superpositions in photoemission and a cross-comparison of spin polarization in photoemission from non-magnetic solids with XMCD on magnetic materials are presented; these are all based upon the influence of the spin-orbit interaction in angle-resolved photoemission.

  16. Simulation study for measurement of horizontal wind profiles in the polar stratosphere and mesosphere using ground-based observations of ozone and carbon monoxide lines in the 230-250 GHz region

    NASA Astrophysics Data System (ADS)

    Newnham, David A.; Ford, George P.; Moffat-Griffin, Tracy; Pumphrey, Hugh C.

    2016-07-01

    Meteorological and atmospheric models are being extended up to 80 km altitude but there are very few observing techniques that can measure stratospheric-mesospheric winds at altitudes between 20 and 80 km to verify model datasets. Here we demonstrate the feasibility of horizontal wind profile measurements using ground-based passive millimetre-wave spectroradiometric observations of ozone lines centred at 231.28, 249.79, and 249.96 GHz. Vertical profiles of horizontal winds are retrieved from forward and inverse modelling simulations of the line-of-sight Doppler-shifted atmospheric emission lines above Halley station (75°37' S, 26°14' W), Antarctica. For a radiometer with a system temperature of 1400 K and 30 kHz spectral resolution observing the ozone 231.28 GHz line we estimate that 12 h zonal and meridional wind profiles could be determined over the altitude range 25-74 km in winter, and 28-66 km in summer. Height-dependent measurement uncertainties are in the range 3-8 m s-1 and vertical resolution ˜ 8-16 km. Under optimum observing conditions at Halley a temporal resolution of 1.5 h for measuring either zonal or meridional winds is possible, reducing to 0.5 h for a radiometer with a 700 K system temperature. Combining observations of the 231.28 GHz ozone line and the 230.54 GHz carbon monoxide line gives additional altitude coverage at 85 ± 12 km. The effects of clear-sky seasonal mean winter/summer conditions, zenith angle of the received atmospheric emission, and spectrometer frequency resolution on the altitude coverage, measurement uncertainty, and height and time resolution of the retrieved wind profiles have been determined.

  17. Vertical constituent transport in the mesosphere

    NASA Technical Reports Server (NTRS)

    Strobel, Darrell F.; Summers, Michael E.; Bevilacqua, Richard M.; Deland, Matthew T.; Allen, Mark

    1987-01-01

    Ground-based microwave spectroscopy measurements of mesospheric CO and H2O vertical mixing ratio profiles are used to infer vertical mixing rates in the upper mesosphere. The CO and H2O data consistently imply vertical eddy diffusion coefficients in the 70- to 85-km region of 100,000-200,000 sq cm/s during spring through summer at midlatidues. Although chemical acceleration of vertical transport is substantial for O and O3, below the mesopause, the divergences of their associated fluxes are modest, with at most a factor of 2 effect on the concentrations of O and O3 for measured variability in gravity wave activity. Comparison of Solar Mesosphere Explorer (SME) O3 data with model results reinforces the conclusions of slow vertical mixing in the upper mesosphere as a consequence of the reduced HO(x) catalytic loss of odd oxygen. The changes in chemical rate constants recommended by Rusch and Eckman (1985), in conjunction with slow vertical mixing, yield good agreement with SME O3 data. The slow vertical mixing deduced in this study is consistent with upper limits obtained from studies of the mesospheric heat budget and could be construed as evidence for an advectively controlled mesosphere. A comparison of the vertical eddy diffusion coefficients for momentum stresses, constituent transport, and heat transport suggests that the eddy Prandtl number must be of order 10.

  18. Vertical constituent transport in the mesosphere

    NASA Astrophysics Data System (ADS)

    Strobel, Darrell F.; Summers, Michael E.; Bevilacqua, Richard M.; Deland, Matthew T.; Allen, Mark

    1987-06-01

    Ground-based microwave spectroscopy measurements of mesospheric CO and H2O vertical mixing ratio profiles are used to infer vertical mixing rates in the upper mesosphere. The CO and H2O data consistently imply vertical eddy diffusion coefficients in the 70- to 85-km region of 100,000-200,000 sq cm/s during spring through summer at midlatidues. Although chemical acceleration of vertical transport is substantial for O and O3, below the mesopause, the divergences of their associated fluxes are modest, with at most a factor of 2 effect on the concentrations of O and O3 for measured variability in gravity wave activity. Comparison of Solar Mesosphere Explorer (SME) O3 data with model results reinforces the conclusions of slow vertical mixing in the upper mesosphere as a consequence of the reduced HO(x) catalytic loss of odd oxygen. The changes in chemical rate constants recommended by Rusch and Eckman (1985), in conjunction with slow vertical mixing, yield good agreement with SME O3 data. The slow vertical mixing deduced in this study is consistent with upper limits obtained from studies of the mesospheric heat budget and could be construed as evidence for an advectively controlled mesosphere. A comparison of the vertical eddy diffusion coefficients for momentum stresses, constituent transport, and heat transport suggests that the eddy Prandtl number must be of order 10.

  19. Mean characteristics of mesosphere winter echoes at mid- and high-latitudes

    NASA Astrophysics Data System (ADS)

    Zeller, O.; Zecha, M.; Bremer, J.; Latteck, R.; Singer, W.

    2006-06-01

    VHF radar observations are used to investigate different regions of the Earth's atmosphere. Strong echoes from the mesosphere are mainly observed during summer months at polar latitudes (polar mesosphere summer echoes [PMSE]), and less often at mid-latitudes (mesosphere summer echoes [MSE]). Interestingly, in recent years similar echoes have been observed during winter months ([polar] mesosphere winter echoes (P)MWE). This paper reports on VHF radar measurements between September and April at Andenes (2001 2005) and Kühlungsborn (2003 2005) to determine the mean features of (P)MWE at polar and mid-latitudes. The (P)MWE are a rare phenomenon with mean occurrence rates of about 2.9% in polar and only 0.3% in mid-latitudes, with a maximum occurrence height at 70.5 km for daytime and 77.5 km for nighttime echoes. The diurnal variation is characterised by a maximum near noon and minimum during nighttime. The seasonal variation of (P)MWE is weak with some indication of an increased number of PMWE during mid-winter. The occurrence rate of (P)MWE is positively correlated with the ionisation level of the D region of the ionosphere. Mainly high-energetic proton (and electron) fluxes and enhanced X-ray radiation are important for the existence of (P)MWE. The second factor for the existence of (P)MWE are irregularities of the refraction index of half the radar wavelength (about 3 m for the radars used in this paper). Neutral air turbulence due to breaking gravity waves seems to be an important process. Whether charged aerosol particles or partial reflections of infrasound have additionally to be considered to explain (P)MWE is currently a point of discussion in the literature.

  20. Temperature trends in the midlatitude summer mesosphere

    NASA Astrophysics Data System (ADS)

    Lübken, F.-J.; Berger, U.; Baumgarten, G.

    2013-12-01

    We have performed trend studies in the mesosphere in the period 1961-2009 with Leibniz-Institute Middle Atmosphere (LIMA) model driven by European Centre for Medium-Range Weather Forecasts reanalysis below approximately 40 km and adapts temporal variations of CO2 and O3 according to observations. Temperatures in the mesosphere/lower thermosphere vary nonuniformly with time, mainly due to the influence of O3. Here we analyze the contribution of varying concentrations of CO2 and O3 to the temperature trend in the mesosphere. It is important to distinguish between trends on pressure altitudes, zp, and geometrical altitudes, zgeo, where the latter includes the effect of shrinking due to cooling at lower heights. For the period 1961-2009, temperature trends on geometrical and pressure altitudes can differ by as much as -0.9 K/dec in the mesosphere. Temperature trends reach approximately -1.3±0.11 K/dec at zp˜60 km and -1.8±0.18 K/dec at zgeo˜70 km, respectively. CO2 is the main driver of these trends in the mesosphere, whereas O3 contributes approximately one third, both on geometrical and pressure heights. Depending on the time period chosen, linear temperature trends can vary substantially. Altitudes of pressure levels in the mesosphere decrease by up to several hundred meters. We have performed long-term runs with LIMA applying twentieth century reanalysis dating back to 1871. Again, trends are nonuniform with time. Since the late nineteenth century, temperatures in the mesosphere have dropped by approximately 5-7 K on pressure altitudes and up to 10-12 K on geometrical altitudes.

  1. Nitrogen isotopic relationship between diatom-bound and bulk organic matter of cultured polar diatoms

    NASA Astrophysics Data System (ADS)

    Horn, Matthew G.; Robinson, Rebecca S.; Rynearson, Tatiana A.; Sigman, Daniel M.

    2011-09-01

    Using batch cultures, the 15N/14N (hereafter δ15N) of diatom-bound organic matter was measured and compared to the δ15N of total diatom biomass during the progressive consumption of a nitrate pool in four polar diatom species (Fragilariopsis cylindrus, Fragilariopsis kerguelensis, Pseudo-nitzschia seriata, and Thalassiosira nordenskioeldii) and one temperate species (Thalassiosira aestivalis). In general, the δ15N of the dissolved nitrate in seawater was greater than that of the biomass, which was greater than that of the diatom-bound N. Rayleigh-type relationships were observed, allowing for estimation of the isotope effect (ɛ) for each species, with a range from 1.0‰ to 14.0‰ across all species. For all cultured strains, the δ15N values of the diatom-bound (δ15NDB) fraction was lower than those of the total diatom biomass (δ15Nbiomass). The isotopic offset between the biomass and diatom-bound N (δ15NDBoffset = δ15Nbiomass - δ15NDB) was relatively constant along the growth curve for each individual species but varied among species, with a range of 1.9‰-11.2‰. Weak relationships were determined when ɛ and the δ15NDBoffset were compared to cellular size and surface area:volume ratio. More significantly, with the exception of Pseudo-nitzschia seriata, a strong positive relationship was found between ɛ and δ15NDBoffset. While the culture data indicate a positive δ15NDBoffset across all studied diatom species, surface sediment data suggest a negative δ15NDBoffset for sedimentary assemblages. This indicates that either (1) the growth conditions of our cultures had some effect on δ15NDBoffset or (2) a low-δ15N component of the N that we measure as diatom frustule-bound is lost during early diagenesis. Given documented assemblage changes, our culture data for relevant species do not suggest that the higher δ15NDB observed in the Antarctic during ice ages can be explained by species related changes in the sedimentary bulk-to-diatom-bound isotopic

  2. Nanodust shedding and its potential influence on dust-related phenomena in the mesosphere

    NASA Astrophysics Data System (ADS)

    Havnes, O.; Hartquist, T. W.

    2016-10-01

    We explore the possibility that some meteoric smoke particles that collide with larger nanoparticles near the mesopause can escape from the larger particles by capturing surface electrons. If the process were sufficiently efficient, under certain conditions it would influence the responses of polar mesospheric summer echoes to artificial heating in a manner that is compatible with observations that are unexplained with previous models. The process would have a number of other possible consequences for nanoparticles near the mesopause.

  3. Decadal Variability in PMCs and Implications for Changing Temperature and Water Vapor in the Upper Mesosphere

    NASA Astrophysics Data System (ADS)

    Hervig, M. E.; Berger, U.; Siskind, D. E.

    2016-12-01

    Observations of polar mesospheric clouds (PMC) from the Solar Backscatter Ultraviolet (SBUV) satellite instruments are used to characterize variability and trends from 1979 - 2014. The SBUV PMC record indicates decadal oscillations during the 1980's and 90's, which are expected to result from the 11-year solar cycle. This oscillation is absent in the recent decade, however, and we speculate that solar cycle effects at PMC altitudes during the 1980's and 90's may have been fortuitously amplified by stratospheric warming due to volcanic eruptions which occurred near solar maximum. SBUV trend results are compared with temperature, water vapor, and PMCs from the Mesospheric Ice Microphysics and Transport (MIMAS) model. Both SBUV and the model indicate positive trends in PMC vertically integrated water content (IWC), which increase towards higher latitudes. Using analysis of Solar Occultation for Ice Experiment (SOFIE) observations, the SBUV IWC trends are expressed in terms of the underlying changes in temperature and water vapor in the upper mesosphere. The SBUV / SOFIE PMC analysis indicates cooling trends that increase towards higher latitudes (-0.5 K / decade at 77N), consistent with the MIMAS model and scant observations. The analysis further indicates increasing water vapor in the NH upper mesosphere ( 1 % / decade at 77N, insignificant in the SH), with values that are consistent with MIMAS but less than expected due to increasing methane.

  4. Seasonal and interannual variability of mesospheric gravity wave activity at high and mid-latitudes

    NASA Astrophysics Data System (ADS)

    Hoffmann, Peter; Singer, Werner; Becker, Erich; Latteck, Ralph; Keuer, Dieter

    The seasonal variation and interannual variability of the gravity wave activity in the mesosphere/lower thermosphere (MLT) region at high and mid-latitudes is investigated. Variations of the gravity wave activity are examined in relation to the filtering processes due to the changes of the background winds, tides and planetary waves. Our studies are basing on wind measurements from meteor and MF radars at Andenes (69° N, 16° E) and Juliusruh (55° N, 13° E). These measurements are supplemented by mesospheric temperatures derived from meteor decay times. Additionally, turbulent energy dissipation rates have been estimated from spectral width measurements using a 3 MHz Doppler radar near Andenes. Particular attention is directed to the influence of the solar activity on the gravity wave activity during the summer months when the mesospheric winds show the strongest correlation with the solar activity. Possible dependencies between the occurrence rates of polar mesospheric summer echoes (PMSE) and the gravity wave activity are discussed. Furthermore, the activity of gravity waves and their dissipation are investigated in winter in relation with wind changes during sudden stratospheric warming (SSW) events. The summer/ winter behavior of the gravity wave activity will be compared to simulations with the simple general circulation model KMCM (K¨hlungsborn Mechanistic u Circulation Model) that extends up to 100 km. In all cases, the percentage rates of the kinetic energy of defined period ranges in relation to the total variances of the horizontal wind fluctuations are estimated.

  5. The effect of natural organic matter polarity and molecular weight on NDMA formation from two antibiotics containing dimethylamine functional groups.

    PubMed

    Leavey-Roback, Shannon L; Krasner, Stuart W; Suffet, Irwin H Mel

    2016-12-01

    N-nitrosodimethylamine (NDMA) is a disinfection byproduct preferentially formed in chloraminated water. NDMA may be formed from certain chemicals containing dimethylamine (DMA) functional groups. This reaction may be slowed by the presence of natural organic matter (NOM). In this study, NOM fractionated by size or polarity was tested for its ability to slow or impede the formation of NDMA from two DMA-containing precursors, the antibiotics tetracycline and spiramycin. The high molecular weight NOM fractions (>10KDa) were shown to be the most effective in reducing the amount of NDMA formed from the precursor chemicals. The filtrate of a C-18 non-polar cartridge was also effective at reducing NDMA formation from tetracycline (spyramycin not tested). Therefore, polar and charged NOM components may be responsible for the reduction in NDMA formation. A possible mechanism for the reduction of NDMA formation from tetracycline is complexation due to the hydrogen bonding of the DMA functional group on tetracycline to polar phenolic functional groups in the NOM. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Active Dust Experiment in the Mesosphere

    SciTech Connect

    Norberg, Carol; Pellinen-Wannberg, Asta

    2008-09-07

    The mesosphere stretches from an altitude of about 50 to 90 km above the Earth's surface. Meteors entering the Earth's atmosphere are believed to ablate and hence give rise to a thin layer of dust particles in the upper part of the Earth's mesosphere. It seems that the dust is most dense in a layer that lies between 80 and 90 km. The dust particles are thought to have sizes of a few to tens of nanometers. Efforts have been made to measure these particles using rockets and radar techniques with limited success. We propose to release dust into the mesosphere over northern Sweden at a height of about 90 km and observe the released dust using the EISCAT radar system. The dust will be launched from the Swedish Space Corporation Esrange Space Centre on a single-stage Improved-Orion rocket that will be launched so that its flight path will be in the radar field of view.

  7. Collision between variably polarized plane gravitational wave and a shell of null matter

    NASA Astrophysics Data System (ADS)

    Feinstein, Alexander; Senovilla, Josém. M.

    1989-06-01

    We construct a solution to the Einstein field equations which describes the collision between a variably polarized gravitational wave and a shell of null dust. Depending on the choice of the parameters the variably polarized wave can have an arbitrarily smooth wavefront. The shell of null dust is followed by a constantly polarized plane gravitational wave. Also Grupo de Física Teórica, Departamento de Física, Ingeniería y Radiología Médica, Facultad de Ciencias, Universidad de Salamanca, 37008 Salamanca, Spain.

  8. The anomalous solid state decomposition of ammonium dinitramide: a matter of surface polarization.

    PubMed

    Rahm, Martin; Brinck, Tore

    2009-05-28

    Polarized dinitramide anions on the surface of solid ammonium dinitramide (ADN) have a decomposition barrier that is reduced by 16 kcal mol(-1) and explain the anomalous solid state decomposition of ADN.

  9. Mesosphere and Lower Thermosphere Wind Models

    NASA Astrophysics Data System (ADS)

    Rees, David

    An overview of existing empirical middle atmosphere wind models is presented, with special emphasis on the widely used CIRA-86 and HWM-93 models. We especially focus on the mesosphere/lower thermosphere (MLT) region. We present results of the recently established Global Empirical Wind Model (GEWM), a new wind climatology (0-120 km) based upon the GEWM, stratospheric reanalysis data, and a numerical model. Supplementary information on the interannual variability of winds, planetary wave activity, tides, and possible trends in the stratosphere and mesosphere is provided.

  10. Mesospheric dynamics and chemistry from SME data

    NASA Technical Reports Server (NTRS)

    Strobel, Darrell F.

    1987-01-01

    A fast Curtis matrix calculation of cooling rates due to the 15 micron band of CO2 is modified to parameterize the detailed calculations by Dickinson (1984) of infrared cooling by CO2 in the mesosphere and lower thermosphere. The calculations included separate NLTE treatment of the different 15 micron bands likely to be important for cooling. The goal was to compress the detailed properties of the different bands into a modified Curtis matrix, which represents one composite band with appropriate averaged radiative properties to allow for a simple and quick calculation of cooling rates given a temperature profile. Vertical constituent transport in the mesosphere was also studied.

  11. A review of mesospheric dynamics and chemistry

    SciTech Connect

    Viereck, R.A. )

    1991-01-01

    Advances made in understanding the chemistry and dynamics of the atmosphere in the approximate altitude range of 50 to 90 km are addressed. Attention is given to mesospheric structure and seasonal variations, gravity waves and gravity wave saturation, the effects of gravity waves on thermal, momentum and constituent fluxes, and the effect of gravity waves on airglow emissions. A review of research on tides and planetary waves and their effects on the mesosphere are presented as well as discussions on ozone hydroxyl, water vapor, and noctilucent cloud research. 217 refs.

  12. Mesospheric gravity waves and their sources at the South Pole

    NASA Astrophysics Data System (ADS)

    Mehta, D.

    2016-12-01

    The sourcing locations and mechanisms for short period, long vertical wavelength upward-propagating gravity waves at high polar latitudes remain largely unknown. Using all-sky imager data from the Amundsen-Scott South Pole Station we determine the spatial and temporal characteristics of 94 observed small-scale waves in three austral winter months in 2003 and 2004. These data, together with background atmospheres from synoptic and/or climatological empirical models, are used to model gravity wave propagation from the polar mesosphere to each wave's source using a ray-tracing model. Our results provide a compelling case that a significant proportion of the observed waves are launched in several discrete layers in the tropopause and/or stratosphere. Analyses of synoptic geopotentials and temperatures indicate that wave formation is a result of baroclinic instability processes in the stratosphere and the interaction of planetary waves with the background wind fields in the tropopause. These results are significant for defining the influences of the polar vortex on the production of these small-scale, upward propagating gravity waves at the highest polar latitudes.

  13. Planetary-scale inertio gravity waves in the Mesosphere

    NASA Astrophysics Data System (ADS)

    Mayr, H. G.; Mengel, J. G.; Talaat, E. R.; Porter, H. S.; Chan, K. L.

    2003-12-01

    In the polar region of the upper mesosphere, horizontal wind oscillations have been observed with periods around 10 hours. Waves with such periods are generated in our Numerical Spectral Model (NSM), and they are identified as planetary-scale inertio gravity waves (IGW). These waves have periods between 9 and 11 hours and appear above 70 km in the zonal mean (m = 0), as well as in m = 1 to 4 propagating eastward and westward. They grow in magnitude to altitudes near 100 km and have vertical wavelengths of about 25 km. The m = 1 westward IGWs have the largest amplitudes, up to 30 m/s at the poles. The IGWs occur intermittently but reveal systematic seasonal variations. Their amplitudes generally are largest in late winter and spring. Numerical experiments show that the waves also appear without tidal excitation. Like the planetary waves in the model, the IGWs are produced by instabilities that arise in the mean zonal circulation.

  14. Micrometeoroid ablation: metal abundances and fate of mesospheric metals

    NASA Astrophysics Data System (ADS)

    Rietmeijer, Frans

    Extraterrestrial materials ~20 micometer to ~1 cm in size entering the Earth's atmosphere include aggregate interplanetary dust particles (IDPs), cluster IDPs, CI and CM type micro-meteorites from periodic comets, the asteroid belt and near-Earth asteroids. This dust interacts with the atmosphere, ablation and evaporation, and causes steady-state mesospheric metal abundances that can be locally perturbed by meteor storms and (meteorite-producing) bolides. Solar system accretion was hierarchical and involved a few recycled non-chondritic dust types, viz. principal components (PCs), Fe,Ni-sulfides, Fe-oxides, (Mg,Fe)-olivine, (Mg,Fe,Ca)-pyroxenes, anorthite, and refractory Al,Ti-rich minerals. The PCs (0.1 - 2.0 micrometer) are carbonaceous units, C-bearing ferro-magnesiosilica, and Ca,Al-bearing ferromagnesiosilica units (i.e. CHON, mixed and silicate dust in comet Halley). Liberation from the parent body by ice sublimation, fragmentation, impact and others, will! disrupt this accretion hierarchy at the weakest textural bond. Micrometeoroid compositions are thus a function of size (the smallest dust is non-chondritic), the nature of their accretion environments and post-accretion textural modification. Collectively Zodiacal dust has the average composition of the combined accretion environments of the contributing sources. Within variations caused by the ablation process itself, mesospheric metals have almost chondritic abundances. I will discuss the mesospheric sodium abundance and Fe/Ni ratio. Sodium is difficult to analyze but there are indications that cometary Na-abundances exceed the cosmic value. Extraterrestrial matter has a unique Fe/Ni ratio. Despite its range due to natural variations among micrometeoroids, it is a diagnostic signature. The first tentative observation of condensed and coagulated meteoric matter included Fe/Ni-dust that was adhered to terrestrial dust in the upper stratosphere at ~35 km altitude along with Ti-oxides, Fe-oxides, silica and

  15. Cell polarity in fission yeast: a matter of confining, positioning, and switching growth zones.

    PubMed

    Huisman, Stephen M; Brunner, Damian

    2011-10-01

    The two key processes in growth polarisation are the generation of a confined region and the correct positioning of that region. Fission yeast has greatly contributed to the study of cell polarisation, particularly in the aspect of growth site positioning, which involves the interphase microtubule cytoskeleton. Here we review the mechanisms of growth polarity in vegetatively growing fission yeast cells. These seemingly simple cells show astonishingly complex growth polarity behaviour, including polarity switching and integrating multiple levels of control by the cell cycle machinery. We aim to extract and highlight the underlying concepts and discuss these in context of current understanding; showing how relevant proteins are networked to integrate the various machineries. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. Getting to the root of plant iron uptake and cell-cell transport: Polarity matters!

    PubMed

    Dubeaux, Guillaume; Zelazny, Enric; Vert, Grégory

    2015-01-01

    Plasma membrane proteins play pivotal roles in mediating responses to endogenous and environmental cues. Regulation of membrane protein levels and establishment of polarity are fundamental for many cellular processes. In plants, IRON-REGULATED TRANSPORTER 1 (IRT1) is the major root iron transporter but is also responsible for the absorption of other divalent metals such as manganese, zinc and cobalt. We recently uncovered that IRT1 is polarly localized to the outer plasma membrane domain of plant root epidermal cells upon depletion of its secondary metal substrates. The endosome-recruited FYVE1 protein interacts with IRT1 in the endocytic pathway and plays a crucial role in the establishment of IRT1 polarity, likely through its recycling to the cell surface. Our work sheds light on the mechanisms of radial transport of nutrients across the different cell types of plant roots toward the vascular tissues and raises interesting parallel with iron transport in mammals.

  17. Seasonal variations of long period oscillations in the mesosphere at high- and mid-latitudes and their relation to mesospheric summer echoes

    NASA Astrophysics Data System (ADS)

    Zeller, Olof; Hoffmann, Peter; Bremer, Juergen; Singer, Werner

    Continuous MF and meteor radar observations allow detailed studies of the wind field in the mesosphere and lower thermosphere, which is characterized by a high variability due to the presence of gravity and tidal waves as well as planetary waves. Here the seasonal variation of long period oscillations (periods of few days) is used to indicate the presence of transient planetary waves in the mesosphere at high and mid-latitudes. Our studies are based on wind measurements from meteor and MF radars at Andenes (69° N, 16° E) and Juliusruh (55° N, 13° E). These measurements are supplemented by mesospheric temperatures derived from meteor decay times. For investigations of wind and temperature oscillations wavelet analyses have been performed showing the seasonal varations of their preferred periods and amplitudes. The activity of oscillations with a period in the range 2 - 4 d have their maximum during summer while the long period ones (˜10 d) occur preferably in winter. Oscillations with periods of 4 - 7 d occur in every season. Such periods are not only observed in wind and temperature variations, but also in variations of (polar) mesosphere summer echos (P)MSE observed by VHF radars in Kuehlungsborn (54° N, 12° E) and Andenes. (P)MSE are connected with very cold temperatures where ice particles can exist. Due to an equatorward directed meridional temperature gradient variations of meridional wind and temperature are positively correlated. Generally radar echoes at mid latitudes are strongly affected by meridional wind variations due to a mean temperature around the frost point of water vapour. In contrast there is mostly no significant impact of the meridional wind on radar echoes at polar latitudes. A mean temperature well below the frost point and a weaker meridional temperature gradient than at mid latitudes are reasons for this reduced impact. But because of higher temperatures in 2002 long period temperature and meridional wind variations impact the PMSE

  18. Ultracold Polar Molecules: New Phases of Matter for Quantum Information and Quantum Control

    DTIC Science & Technology

    2013-06-01

    Devil’s staircase” where Mott solids appear at rational fillings of the lattice.   Studied 1D  fermionic  and bosonic gases with repulsive power‐law...superfluid transition in single‐component  fermionic  gas in a trap with dipole  moments polarized in perpendicular layers, finding that many‐body effects...Zoller, Bilayer superfluidity of fermionic polar molecules: Many‐Body effects, Phys. Rev. A 83, 043602 (2011).  2012 Phase   1) N. Henkel, F. Cinti, P

  19. Anisotropic Optical Response of Dense Quark Matter under Rotation: Compact Stars as Cosmic Polarizers

    NASA Astrophysics Data System (ADS)

    Hirono, Yuji; Nitta, Muneto

    2012-08-01

    Quantum vortices in the color-flavor locked phase of QCD have bosonic degrees of freedom, called the orientational zero modes, localized on them. We show that the orientational zero modes are electromagnetically charged. As a result, a vortex in the color-flavor locked phase nontrivially interacts with photons. We show that a lattice of vortices acts as a polarizer of photons with wavelengths larger than some critical length.

  20. Ground-based Observations and Atmospheric Modelling of Energetic Electron Precipitation Effects on Antarctic Mesospheric Chemistry

    NASA Astrophysics Data System (ADS)

    Newnham, D.; Clilverd, M. A.; Horne, R. B.; Rodger, C. J.; Seppälä, A.; Verronen, P. T.; Andersson, M. E.; Marsh, D. R.; Hendrickx, K.; Megner, L. S.; Kovacs, T.; Feng, W.; Plane, J. M. C.

    2016-12-01

    The effect of energetic electron precipitation (EEP) on the seasonal and diurnal abundances of nitric oxide (NO) and ozone in the Antarctic middle atmosphere during March 2013 to July 2014 is investigated. Geomagnetic storm activity during this period, close to solar maximum, was driven primarily by impulsive coronal mass ejections. Near-continuous ground-based atmospheric measurements have been made by a passive millimetre-wave radiometer deployed at Halley station (75°37'S, 26°14'W, L = 4.6), Antarctica. This location is directly under the region of radiation-belt EEP, at the extremity of magnetospheric substorm-driven EEP, and deep within the polar vortex during Austral winter. Superposed epoch analyses of the ground based data, together with NO observations made by the Solar Occultation For Ice Experiment (SOFIE) onboard the Aeronomy of Ice in the Mesosphere (AIM) satellite, show enhanced mesospheric NO following moderate geomagnetic storms (Dst ≤ -50 nT). Measurements by co-located 30 MHz riometers indicate simultaneous increases in ionisation at 75-90 km directly above Halley when Kp index ≥ 4. Direct NO production by EEP in the upper mesosphere, versus downward transport of NO from the lower thermosphere, is evaluated using a new version of the Whole Atmosphere Community Climate Model incorporating the full Sodankylä Ion Neutral Chemistry Model (WACCM SIC). Model ionization rates are derived from the Polar orbiting Operational Environmental Satellites (POES) second generation Space Environment Monitor (SEM 2) Medium Energy Proton and Electron Detector instrument (MEPED). The model data are compared with observations to quantify the impact of EEP on stratospheric and mesospheric odd nitrogen (NOx), odd hydrogen (HOx), and ozone.

  1. Possibilities of Diagnosing Mesospheric Dust Layers During Ionospheric Heating Experiments

    NASA Astrophysics Data System (ADS)

    Scales, Wayne; Mahmoudian, Alireza

    2012-07-01

    Over the past decade, significant advances have been made in understanding physical processes associated with heating mesospheric dust layers with high power radiowaves. The principal signature associated with this heating, which increases the electron temperature, is the modulation of Polar Mesospheric Summer Echoes PMSEs which are strong radar echoes from electron irregularities due to the presence of the charged dust layer. Particularly important is the modulation of PMSE strength during the periods after the turn-on and turn-off of the radiowave heating. Such periods have been proposed to provide significant diagnostic information about the dust layer and have lead to this being a vigorous field of investigation. At this time, several computational models have been developed that can reproduce important aspects of the temporal behavior during the experiments, however, a key objective to furthering experimental progress is to continue to develop strategies to obtain critical diagnostic information on the dust layer. The focus of this talk is to present simplified analytical models that 1) elucidate the fundamental dusty plasma physics of the processes during the turn-on and turn-off of radiowave heating and 2) are much more amenable to directly providing diagnostic information on the dust layer than the complicated computational models of the past. During the first part of the presentation, the formulation and application of the simplified models are discussed. It is then shown that using a multi-frequency experimental measurement is expected to provide enough observables to determine critical diagnostic information on the dust layer such as the dust density altitude profile, average charge state, and electron temperature in the heated volume.

  2. Comparison of two polarity measurements of hydrophobic organic matter for the evaluation of water treatment processes: XAD resin and PRAM.

    PubMed

    Philibert, Marc; Rosario-Ortiz, Fernando; Suffet, Mel

    2012-01-01

    Dissolved organic matter (DOM) is a mixture of thousands of organic molecules wide-ranging in molecular weight, polarity and physicochemical properties. DOM is responsible for multiple water treatment issues such as trihalomethane (THM) formation potential and membrane fouling. Two methods of evaluating the polarity of DOM are being used for water treatment application: a serial XAD resin adsorption method at acid pH and the polarity rapid assessment method (PRAM) by parallel solid phase extraction (SPE) cartridges at natural pH. These two methods have been described by their authors as able to define a hydrophobic fraction though they do so by sorption onto different types of material at different pHs. The first part of this study compared the PRAM and XAD methods and showed that the hydrophobic fractions defined by the two approaches were not correlated. This result highlighted the difficulties in defining fractions as 'hydrophobic material'. It appeared that the sorbents for XAD-8 (an acrylic polymer containing oxygen) at pH <3 and C-18 (a pure hydrocarbon polymer coating on silica particles) at neutral or pH <3 did not retain similar hydrophobic fractions. This hypothesis was verified by fluorescence spectroscopy of the effluent of the XAD-8 resin and PRAM C-18 SPE cartridge. Finally the study concentrated on the use of fluorescence and ultrafiltration methods in series with PRAM to gain more insight into the structure and characteristics of the hydrophobic DOM present in drinking water sources. This evaluation showed that the smaller molecular weight fraction of DOM (<1 kDa) had a higher percentage of hydrophobic character and that the fluorescence-defined aromatic protein fraction was the most hydrophilic.

  3. The impact of emotion intensity on recognition memory: Valence polarity matters.

    PubMed

    Meng, Xianxin; Zhang, Ling; Liu, Wenwen; Ding, XinSheng; Li, Hong; Yang, Jiemin; Yuan, JiaJin

    2017-06-01

    Although the effects of emotion of different emotional intensity on memory have been investigated, it remain unclear whether the influence of emotional intensity on memory varies depending on the stimulus valence polarity (i.e., positive or negative). To address this, event-related potentials were recorded when subjects performed a continuous old/new discrimination task, for highly negative (HN), mildly negative (MN) and neutral pictures in the negative session; and for highly positive (HP), mildly positive (MP) and neutral pictures in the positive session. The results showed that relative to neutral stimuli, both HN and MN stimuli showed increased memory discrimination scores, and enhanced old/new effect in early FN400 (Frontal Negativity), but not late positive component (LPC) amplitudes. By contrast, relative to MP stimuli, HP and neutral stimuli showed increased memory discrimination scores and enhanced old/new effect in LPC but not FN400 amplitudes. Additionally, we observed a significant positive correlation between the memory discrimination score and the old/new effect in the amplitudes of the FN400 and LPC, respectively. These results indicate that both HN and MN stimuli were remembered better than neutral stimuli; whereas the recognition was worse for MP stimuli than Neutral and HP stimuli. In conclusion, in the present study, we observed that the effect of emotion intensity on memory depends on the stimulus valence polarity. Copyright © 2017. Published by Elsevier B.V.

  4. Sprite streamer initiation from natural mesospheric structures.

    PubMed

    Liu, Ningyu; Dwyer, Joseph R; Stenbaek-Nielsen, Hans C; McHarg, Matthew G

    2015-06-29

    Sprites are large, luminous electrical discharges in the upper atmosphere caused by intense cloud-to-ground lightning flashes, manifesting an impulsive coupling mechanism between lower and upper atmospheric regions. Their dynamics are governed by filamentary streamer discharges whose propagation properties have been well studied by past work. However, how they are initiated is still under active debate. It has recently been concluded that ionospheric/mesospheric inhomogeneities are required for their initiation, but it is an open question as to what the sources of those inhomogeneities are. Here we present numerical simulation results to demonstrate that naturally-existing, small-scale mesospheric structures such as those created by gravity waves via instability and breaking are viable sources. The proposed theory is supported by a recent, unique high-speed observation from aircraft flying at 14-km altitude. The theory naturally explains many aspects of observed sprite streamer initiation and has important implications for future observational work.

  5. Mesospheric dust observations during the MAXIDUSTY campaign

    NASA Astrophysics Data System (ADS)

    Antonsen, Tarjei; Havnes, Ove; Fredriksen, Åshild; Friedrich, Martin; Sternovsky, Zoltan; Plane, John; Hartquist, Tom; Olsen, Sveinung; Eilertsen, Yngve; Trondsen, Espen; Mann, Ingrid; Hedin, Jonas; Gumbel, Jörg; Moen, Jøran; Latteck, Ralph; Baumgarten, Gerd; Höffner, Josef; Williams, Bifford; Hoppe, Ulf-Peter; Karlberg, Jan-Ove

    2017-04-01

    The MAXIDUSTY rocket payloads, launched from Andøya June 30 and July 8 2016, were equipped with dust impact detectors aiming to characterize mesospheric dust charge state, mass distribution of impact fragments and NLC/PMSE structure. One of the main scientific objectives for the campaign was to confirm that material of meteoric origin is abundant inside the icy mesospheric dust particles. The rockets were launched simultaneously with PMSE and NLC (MAXIDUSTY-1) and PMSE (MAXIDUSTY-1B) respectively, and radar measurements were made coincident with the rocket flight path. We report here on the initial results from the rocket probes and remote soundings, with emphasis on the dust impact detector results. Results from the Multiple Dust Detector (MUDD) confirm that NLC ice particles probably have a relatively high content of meteoric smoke particles with a filling factor of up to several percent. Comparisons of the DUSTY faraday bucket and PMSE show that there is no simple correlation between the two.

  6. Model ozone photochemistry on the basis of Solar Mesosphere Explorer mesospheric observations

    NASA Technical Reports Server (NTRS)

    Clancy, R. T.; Rusch, D. W.; Thomas, R. J.; Allen, M.; Eckman, R. S.

    1987-01-01

    Morning and afternoon mesospheric ozone profiles (50-90 km) measured by the Solar Mesosphere Explorer (SME) satellite are analyzed with one-dimensional photochemical models. The observed ozone abundances are 40 percent and 100 percent greater than the model ozone abundances at 50 and 80 km, respectively. Diurnal model calculations are compared with SME observations of ozone profiles at about 0400 and 1400 LT for high northern summer latitudes. Analysis of the ratios of these early morning and midafternoon ozone profiles provides the additional constraint that larger odd-oxygen production rates are required if lower odd-hydrogen activity is invoked to increase model O3 abundances. The increase in odd-oxygen production must be solar zenith angle independent in the mesosphere, ruling out significant changes in the Schumann-Runge band O2 opacities from Allen and Frederrick (1982).

  7. Model ozone photochemistry on the basis of Solar Mesosphere Explorer mesospheric observations

    NASA Technical Reports Server (NTRS)

    Clancy, R. T.; Rusch, D. W.; Thomas, R. J.; Allen, M.; Eckman, R. S.

    1987-01-01

    Morning and afternoon mesospheric ozone profiles (50-90 km) measured by the Solar Mesosphere Explorer (SME) satellite are analyzed with one-dimensional photochemical models. The observed ozone abundances are 40 percent and 100 percent greater than the model ozone abundances at 50 and 80 km, respectively. Diurnal model calculations are compared with SME observations of ozone profiles at about 0400 and 1400 LT for high northern summer latitudes. Analysis of the ratios of these early morning and midafternoon ozone profiles provides the additional constraint that larger odd-oxygen production rates are required if lower odd-hydrogen activity is invoked to increase model O3 abundances. The increase in odd-oxygen production must be solar zenith angle independent in the mesosphere, ruling out significant changes in the Schumann-Runge band O2 opacities from Allen and Frederrick (1982).

  8. Spin-dependent structure functions in nuclear matter and the polarized EMC effect

    SciTech Connect

    I.C. Cloet; W. Bentz; A.W. Thomas

    2005-04-01

    An excellent description of both spin-independent and spin-dependent quark distributions and structure functions has been obtained with a modified Nambu-Jona-Lasinio model, which is free of unphysical thresholds for nucleon decay into quarks--hence incorporating an important aspect of confinement. We utilize this model to investigate nuclear medium modifications to structure functions, and find that we are readily able to reproduce both nuclear matter saturation and the experimental F{sub 2N}{sup A}/F{sub 2N} ratio, that is, the EMC effect. Applying this framework to determine g{sub 1p}{sup A}, we find that the ratio g{sub 1p}{sup A}/g{sub 1p} differs significantly from 1, with the quenching caused by the nuclear medium being about twice that of the spin-independent case. This represents an exciting result, which if confirmed experimentally, will reveal much about the quark structure of nuclear matter.

  9. Circulation Changes in the Mesosphere and the Lower Thermosphere Associated with Sudden Stratospheric Warmings

    NASA Astrophysics Data System (ADS)

    Hirooka, T.; Iwao, K.

    2016-12-01

    Influences of sudden stratospheric warmings (SSWs) reach the mesosphere and the thermosphere. Recently, significant global cooling during SSWs in the thermosphere have been reported on the basis of numerical simulations. However, observational studies are insufficient for the region, so that detailed 3-dimendional structure and the dynamical mechanism are still unclear. Hence, we investigate circulation changes in the mesosphere and thermosphere along with in the stratosphere during SSWs by using TIMED/SABER satellite data and radar data. The SABER observes the atmospheric temperature field in high altitudes up to the lower thermosphere (ca. 120km). Time series of the SABER data includes tidal components, because the satellite orbit is not sun-synchronous and the local time of observation gradually decreases at a specific latitude. The perfect separation of the time series data into tidal and daily changes is difficult especially when diurnal components are amplified. Therefore, we additionally analyze the radar data at some selected stations. Resultantly, north polar temperatures during SSWs show lower thermosphere warming and mesospheric cooling along with the anti-correlated temperature changes in the wide region except over the north pole. In the presentation, we discuss further detailed features of circulation changes associated with SSWs.

  10. Mesospheric intrusion and anomalous chemistry during and after a major stratospheric sudden warming

    NASA Astrophysics Data System (ADS)

    Kvissel, Ole-Kristian; Orsolini, Yvan J.; Stordal, Frode; Limpasuvan, Varavut; Richter, Jadwiga; Marsh, Dan R.

    2012-04-01

    Several major stratospheric sudden warmings (SSWs) characterized by a rapid vertical displacement of the winter polar stratopause are simulated in the National Center for Atmospheric Research's Whole Atmosphere Community Climate Model. The stratopause descends into the mid-stratosphere at the onset of the SSW, and then abruptly reforms near 70 km. The SSWs are accompanied by a strong equatorward and downward residual circulation between 40 and 60 km. The descent occurs mainly through the core of the highly displaced vortex, and is accompanied by an intrusion of air rich in carbon monoxide (CO) from the mesosphere into the mid-stratosphere. Around the periods when the stratopause undergoes rapid vertical displacement, the simulation shows that the air of mesospheric origin is being cut off and remains distinct from surrounding stratospheric air masses for at least a month after SSW onset. Such mesospheric cut-off intrusion of CO-rich appears to be a defining signature of winters with major SSWs. Due to its strong temperature dependency, the secondary ozone maximum (between 90 and 110 km) abruptly decreases in amplitude at the time of the high-altitude stratopause reformation that influences the thermal structure at these altitudes. The vertical location of the tertiary ozone maximum (between 70 and 75 km) shows significant variations in response to the changing vertical motion during SSW.

  11. High-Resolution Infra-Red Imaging Studies of Mesospheric Gravity Waves (Invited)

    NASA Astrophysics Data System (ADS)

    Taylor, M. J.; Pautet, P.; Zhao, Y.; Pendleton, W. R.; Yuan, T.; Esplin, R.; McLain, D.; Fritts, D. C.; Stober, G.

    2013-12-01

    This presentation highlights new research capabilities and recent results focusing on polar latitudes using two new infra-red imaging systems operating at the ALOMAR Arctic Observatory, Norway and at the Amundsen-Scott Base, South Pole, Antarctica. The Advanced Mesospheric Temperature Mapper (AMTM) is a novel infrared digital imaging system that measures selected emission lines in the mesospheric OH (3,1) band (at ~1.5μm) to create high-quality intensity and temperature maps of a broad spectrum of mesospheric gravity waves (with periods ranging from several minutes to many hours). The data are obtained with an unprecedented spatial (~0.5 km) and temporal (typically 30 sec) resolution over a large 120° field of view enabling detailed measurements of wave propagation and dissipation at the ~87 km level, even in the presence of strong aurora. Several new results will be presented and discussed, including high-resolution imaging studies of gravity wave breaking, first evidence of gravity wave 'self-acceleration' and new coordinated lidar, radar and AMTM measurements of gravity wave propagation and ducting at mid-latitudes.

  12. Evolution of stationary wave patterns in mesospheric water vapor due to climate change

    NASA Astrophysics Data System (ADS)

    Demirhan Barı, Deniz; Gabriel, Axel; Sezginer Ünal, Yurdanur

    2016-07-01

    The variability in the observed stationary wave patterns of the mesospheric water vapor (H2O) is investigated using CMIP5 RCP 4.5 and RCP 8.5 projections. The change in the vertical and meridional wave structure at northern mid- and polar latitudes associated to the zonal and meridional eddy heat fluxes is discussed by analyzing the advection of H2O due to residual wind components. The alteration in the characteristics of the stationary wave-1 pattern of the lower mesospheric H2O (up to about 75km) related to change in the projected radiative forcing is observed for the years from 2006 to 2100. Additionally the remarkable effect of the increase in global temperature on the zonal asymmetries in small-scale transient waves and parameterized gravity waves, which largely contribute to the observed stationary wave patterns of H2O in the upper mesosphere, is analyzed. For validation purposes, the derived stratospheric patterns are verified against the eddy heat fluxes and residual advection terms derived from Aura/MLS satellite data between 2004-2010 and the reference period of the CMIP5 MPI dataset (1976-2005) providing confidence in the applied method.

  13. Circulation Changes in the Mesosphere and the Lower Thermosphere Associated with Sudden Stratospheric Warmings

    NASA Astrophysics Data System (ADS)

    Hirooka, Toshihiko; Iwao, Koki

    2016-07-01

    Influences of sudden stratospheric warmings (SSWs) reach the mesosphere and the thermosphere. Recently, significant global cooling during SSWs in the thermosphere have been reported on the basis of numerical simulations. However, observational studies are insufficient for the region, so that detailed 3-dimendional structure and the dynamical mechanism are still unclear. Hence, we investigate circulation changes in the mesosphere and thermosphere along with in the stratosphere during SSWs by using TIMED/SABER satellite data and radar data. The SABER observes the atmospheric temperature field in high altitudes up to the lower thermosphere (~120km). Time series of the SABER data includes tidal components, because the satellite orbit is not sun-synchronous and the local time of observation gradually decreases at a specific latitude. The perfect separation of the time series data into tidal and daily changes is difficult especially when diurnal components are amplified. Therefore, we additionally analyze the radar data at some selected stations. Resultantly, north polar temperatures during SSWs show lower thermosphere warming and mesospheric cooling along with the anti-correlated temperature changes in the wide region except over the north pole. In the presentation, we discuss further detailed features of circulation changes associated with SSWs.

  14. Stratospheric and solar cycle effects on long-term variability of mesospheric ice clouds

    NASA Astrophysics Data System (ADS)

    Lübken, F.-J.; Berger, U.; Baumgarten, G.

    2009-01-01

    Model results of mesospheric ice layers and background conditions at 69°N from 1961 to 2008 are analyzed. The model nudges to European Centre for Medium-Range Weather Forecasts data below ˜45 km. Greenhouse gas concentrations in the mesosphere are kept constant. At polar mesospheric cloud (PMC) altitudes (83 km) temperatures decrease until the mid 1990s by -0.08 K/yr resulting in trends of PMC brightness, occurrence rates, and, to a lesser extent, in PMC altitudes (-0.0166 km/yr). Ice layer trends are consistent with observations by ground-based and satellite instruments. Water vapor increases at PMC heights and decreases above due to increased freeze-drying caused by the temperature trend. Temperature trends in the mesosphere mainly come from shrinking of the stratosphere and from dynamical effects. A solar cycle modulation of H2O is observed in the model consistent with satellite observations. The effect on ice layers is reduced because of redistribution of H2O by freeze-drying. The accidental coincidence of low temperatures and solar cycle minimum in the mid 1990s leads to an overestimation of solar effects on ice layers. A strong correlation between temperatures and PMC altitudes is observed. Applied to historical measurements this gives negligible temperature trends at PMC altitudes (˜0.01-0.02 K/yr). Strong correlations between PMC parameters and background conditions deduced from the model confirm the standard scenario of PMC formation. The PMC sensitivity on temperatures, water vapor, and Ly-α is investigated. PMC heights show little variation with background parameters whereas brightness and occurrence rates show large variations. None of the background parameters can be ignored regarding its influence on ice layers.

  15. Stratospheric and solar cycle effects on long-term variability of mesospheric ice clouds

    NASA Astrophysics Data System (ADS)

    Lübken, F.-J.; Berger, U.; Baumgarten, G.

    2009-11-01

    Model results of mesospheric ice layers and background conditions at 69°N from 1961 to 2008 are analyzed. The model nudges to European Centre for Medium-Range Weather Forecasts data below ˜45 km. Greenhouse gas concentrations in the mesosphere are kept constant. At polar mesospheric cloud (PMC) altitudes (83 km) temperatures decrease until the mid 1990s by -0.08 K/yr resulting in trends of PMC brightness, occurrence rates, and, to a lesser extent, in PMC altitudes (-0.0166 km/yr). Ice layer trends are consistent with observations by ground-based and satellite instruments. Water vapor increases at PMC heights and decreases above due to increased freeze-drying caused by the temperature trend. Temperature trends in the mesosphere mainly come from shrinking of the stratosphere and from dynamical effects. A solar cycle modulation of H2O is observed in the model consistent with satellite observations. The effect on ice layers is reduced because of redistribution of H2O by freeze-drying. The accidental coincidence of low temperatures and solar cycle minimum in the mid 1990s leads to an overestimation of solar effects on ice layers. A strong correlation between temperatures and PMC altitudes is observed. Applied to historical measurements this gives negligible temperature trends at PMC altitudes (˜0.01-0.02 K/yr). Strong correlations between PMC parameters and background conditions deduced from the model confirm the standard scenario of PMC formation. The PMC sensitivity on temperatures, water vapor, and Ly-α is investigated. PMC heights show little variation with background parameters whereas brightness and occurrence rates show large variations. None of the background parameters can be ignored regarding its influence on ice layers.

  16. Polar Mesosphere Winter Echoes: Turbulence Versus Acoustic Waves

    NASA Astrophysics Data System (ADS)

    Belova, E.; Kirkwood, S.; Dalin, P. A.

    2013-12-01

    PMWE are strong echoes from 50-80 km altitudes seen by VHF radars in the equinox and winter seasons. The PMWE observational facts are controversial and the echo origin is still under debate. Two main hypotheses were proposed: one explains PMWE by scattering on turbulent structures and another one suggests these structures to be created by sound waves propagated from below. Strong PMWE are relatively rare phenomena, in most cases the radars observe them during extra ionisation in the lower ionosphere. The current solar maximum provides favourable conditions for PMWE observations and in winter 2012-2013 we collected PMWE data using a 50-MHz radar ESRAD located in the Northern Sweden. We will discuss how main characteristics of the echoes support turbulent or non-turbulent origin of PMWE.

  17. Infrared and Ionization Structure of the Polar Mesosphere

    DTIC Science & Technology

    1988-08-01

    FY85; $100,231, FY86; $94,218, FY87 SENIOR RESEARCH PERSONNEL: Dr. Kay D. Baker Dr. Michael Kelley JUNIOR RESEARCH PERSONNEL: Mr. Glenn Berg PUBLICATIONS...00 CD In Q 0 0 in C) in-n CL C’! 1-4C OU3 0 %V 0 00 C#4 -u C) o 00 I-H jt44 Cl u’s D inCC cra Go P- t BOMM ~00 13- and density measurements and the

  18. Observation of 27 day solar cycles in the production and mesospheric descent of EPP-produced NO

    NASA Astrophysics Data System (ADS)

    Hendrickx, K.; Megner, L.; Gumbel, J.; Siskind, D. E.; Orsolini, Y. J.; Tyssøy, H. Nesse; Hervig, M.

    2015-10-01

    Nitric oxide (NO) is produced by energetic particle precipitation (EPP) in the mesosphere-lower thermosphere (MLT) region, and during the polar winter, NO can descend to stratospheric altitudes where it destroys ozone. In this paper, we study the general scenario, as opposed to a case study, of NO production in the thermosphere due to energetic particles in the auroral region. We first investigate the relationship between NO production and two geomagnetic indices. The analysis indicates that the auroral electrojet index is a more suitable proxy for EPP-produced NO than the typically used midlatitude Ap index. In order to study the production and downward transport of NO from the lower thermosphere to the mesosphere, we perform superposed epoch analyses on NO observations made by the Solar Occultation For Ice Experiment instrument on board the Aeronomy of Ice in the Mesosphere satellite. The epoch analysis clearly shows the impact of the 27 day solar cycle on NO production. The effect is observed down to an altitude range of about 50 km to 65 km, depending on the hemisphere and the occurrence of stratospheric warmings. Initially, a rapid downward transport is noted during the first 10 days after EPP onset to an altitude of about 80-85 km, which is then followed by a slower downward transport of approximately 1-1.2 km/d to lower mesospheric altitudes in the order of 30 days.

  19. An analysis of Solar Mesospheric Explorer temperatures for the upper stratosphere and mesosphere

    NASA Technical Reports Server (NTRS)

    Clancy, R. Todd; Rusch, David W.

    1993-01-01

    We proposed to analyze Solar Mesosphere Explorer (SME) limb profiles of Rayleigh scattered solar flux at wavelengths of 304, 313, and 443 nm to retrieve atmospheric temperature profiles over the 40-65 km altitude region. These temperatures can be combined with the previous analysis of SME 296 nm limb radiances to construct a monthly average climatology of atmospheric temperatures over the 40-90 km, upper stratosphere-mesosphere region, with approximately 4 km vertical resolution. We proposed to investigate the detailed nature of the global temperature structure of this poorly measured region, based on these 1982-1986 SME temperatures. The average vertical structure of temperatures between the stratopause and mesopause has never been determined globally with vertical resolution sufficient to retrieve even scale-height structures. Hence, the SME temperatures provided a unique opportunity to study the detailed thermal structure of the mesosphere, in advance of Upper Atmosphere Research Satellite (UARS) measurements and the Thermosphere Ionosphere Mesosphere Energy and Dynamics (TIMED) mission.

  20. Characterizing the compositional variation of dissolved organic matter over hydrophobicity and polarity using fluorescence spectra combined with principal component analysis and two-dimensional correlation technique.

    PubMed

    Su, Ben-Sheng; Qu, Zhen; He, Xiao-Song; Song, Ying-Hao; Jia, Li-Min

    2016-05-01

    Dissolved organic matter (DOM) obtained from three leachates with different landfill ages was fractionated, and its compositional variation based on hydrophobicity and polarity was characterized by synchronous fluorescence spectra combined with principal component analysis (PCA) and two-dimensional correlation technique. The results showed that the bulk DOM and its fractions were comprised of tryosine-, tryptophan-, fulvic-, and humic-like substances. Tyrosine-like matter was dominant in the young leachate DOM and its fractions, while tryptophan-, fulvic-, and humic-like substances were the main components in the intermediate and old leachate DOMs and their fractions. Tryosine-, tryptophan-, fulvic-, and humic-like substances varied concurrently with the hydrophobicity and polarity. However, the change ratio of these substances was different for the three leachates. Tyrosine-like matter, humic-like materials, and fulvic-like substances were the most sensitive to the hydrophobicity and polarity in the young, intermediate, and old leachates, respectively. Such an integrated approach jointly enhances the characterization of the hydrophobicity- and polarity-dependent DOM fractions and provides a promising way to elucidate the environmental behaviors of different DOM species.

  1. Nanofiltration and Tight Ultrafiltration Membranes for Natural Organic Matter Removal—Contribution of Fouling and Concentration Polarization to Filtration Resistance

    PubMed Central

    Winter, Joerg; Bérubé, Pierre

    2017-01-01

    Nanofiltration (NF) and tight ultrafiltration (tight UF) membranes are a viable treatment option for high quality drinking water production from sources with high concentrations of contaminants. To date, there is limited knowledge regarding the contribution of concentration polarization (CP) and fouling to the increase in resistance during filtration of natural organic matter (NOM) with NF and tight UF. Filtration tests were conducted with NF and tight UF membranes with molecular weight cut offs (MWCOs) of 300, 2000 and 8000 Da, and model raw waters containing different constituents of NOM. When filtering model raw waters containing high concentrations of polysaccharides (i.e., higher molecular weight NOM), the increase in resistance was dominated by fouling. When filtering model raw waters containing humic substances (i.e., lower molecular weight NOM), the increase in filtration resistance was dominated by CP. The results indicate that low MWCO membranes are better suited for NOM removal, because most of the NOM in surface waters consist mainly of humic substances, which were only effectively rejected by the lower MWCO membranes. However, when humic substances are effectively rejected, CP can become extensive, leading to a significant increase in filtration resistance by the formation of a cake/gel layer at the membrane surface. For this reason, cross-flow operation, which reduces CP, is recommended. PMID:28671604

  2. Rocket measurements of mesospheric ionization irregularities

    NASA Technical Reports Server (NTRS)

    Stoltzfus, R. B.; Bowhill, S. A.

    1985-01-01

    The Langmuir probe technique for measurement of electron concentration in the mesosphere is capable of excellent altitude resolution, of order 1 m. Measurements from nine daytime rocket flights carrying an electron density fine structure experiment frequently show small scale ionization structures in the altitude region 70 to 90 km. The irregularities are believed to be the result of turbulent advection of ions and electrons. The fine structure experiment flown by the University of Illinois is described and methods of analyzing the collected data is presented. Theories of homogeneous, isotropic turbulence are reviewed. Power spectra of the measured irregularities are calculated and compared to spectra predicted by turbulence theories.

  3. HDAC inhibition prevents white matter injury by modulating microglia/macrophage polarization through the GSK3β/PTEN/Akt axis

    PubMed Central

    Wang, Guohua; Shi, Yejie; Jiang, Xiaoyan; Leak, Rehana K.; Hu, Xiaoming; Wu, Yun; Pu, Hongjian; Li, Wei-Wei; Tang, Bo; Wang, Yun; Gao, Yanqin; Zheng, Ping; Bennett, Michael V. L.; Chen, Jun

    2015-01-01

    Severe traumatic brain injury (TBI) elicits destruction of both gray and white matter, which is exacerbated by secondary proinflammatory responses. Although white matter injury (WMI) is strongly correlated with poor neurological status, the maintenance of white matter integrity is poorly understood, and no current therapies protect both gray and white matter. One candidate approach that may fulfill this role is inhibition of class I/II histone deacetylases (HDACs). Here we demonstrate that the HDAC inhibitor Scriptaid protects white matter up to 35 d after TBI, as shown by reductions in abnormally dephosphorylated neurofilament protein, increases in myelin basic protein, anatomic preservation of myelinated axons, and improved nerve conduction. Furthermore, Scriptaid shifted microglia/macrophage polarization toward the protective M2 phenotype and mitigated inflammation. In primary cocultures of microglia and oligodendrocytes, Scriptaid increased expression of microglial glycogen synthase kinase 3 beta (GSK3β), which phosphorylated and inactivated phosphatase and tensin homologue (PTEN), thereby enhancing phosphatidylinositide 3-kinases (PI3K)/Akt signaling and polarizing microglia toward M2. The increase in GSK3β in microglia and their phenotypic switch to M2 was associated with increased preservation of neighboring oligodendrocytes. These findings are consistent with recent findings that microglial phenotypic switching modulates white matter repair and axonal remyelination and highlight a previously unexplored role for HDAC activity in this process. Furthermore, the functions of GSK3β may be more subtle than previously thought, in that GSK3β can modulate microglial functions via the PTEN/PI3K/Akt signaling pathway and preserve white matter homeostasis. Thus, inhibition of HDACs in microglia is a potential future therapy in TBI and other neurological conditions with white matter destruction. PMID:25691750

  4. The near‐global mesospheric potassium layer: Observations and modeling

    PubMed Central

    Dawkins, E. C. M.; Chipperfield, M. P.; Feng, W.

    2015-01-01

    Abstract The meteoric metal layers act as unique tracers of chemistry and dynamics in the upper atmosphere. Existing lidar studies from a few locations show that K exhibits a semiannual seasonality (winter and summer maxima), quite unlike the annual seasonality (winter maximum and summer minimum) seen with Na and Fe. This work uses spaceborne observations made with the Optical Spectrograph and InfraRed Imager System instrument on the Odin satellite to retrieve the near‐global K layer for the first time. The satellite data (2004 to mid‐2013) are used to validate the implementation of a recently proposed potassium chemistry scheme in a whole atmosphere chemistry climate model, which provides a chemical basis for this semiannual seasonal behavior. The satellite and model data show that this semiannual seasonality is near global in extent, with the strongest variation at middle and high latitudes. The column abundance, centroid layer height, and root‐mean‐square width of the K layer are consistent with the limited available lidar record. The K data set is then used to investigate the impact of polar mesospheric clouds on the metal layers at high latitudes during summer. Finally, the occurrence frequency of sporadic K layers and their possible link to sporadic E layers are examined. PMID:27478716

  5. The near-global mesospheric potassium layer: Observations and modeling

    NASA Astrophysics Data System (ADS)

    Dawkins, E. C. M.; Plane, J. M. C.; Chipperfield, M. P.; Feng, W.

    2015-08-01

    The meteoric metal layers act as unique tracers of chemistry and dynamics in the upper atmosphere. Existing lidar studies from a few locations show that K exhibits a semiannual seasonality (winter and summer maxima), quite unlike the annual seasonality (winter maximum and summer minimum) seen with Na and Fe. This work uses spaceborne observations made with the Optical Spectrograph and InfraRed Imager System instrument on the Odin satellite to retrieve the near-global K layer for the first time. The satellite data (2004 to mid-2013) are used to validate the implementation of a recently proposed potassium chemistry scheme in a whole atmosphere chemistry climate model, which provides a chemical basis for this semiannual seasonal behavior. The satellite and model data show that this semiannual seasonality is near global in extent, with the strongest variation at middle and high latitudes. The column abundance, centroid layer height, and root-mean-square width of the K layer are consistent with the limited available lidar record. The K data set is then used to investigate the impact of polar mesospheric clouds on the metal layers at high latitudes during summer. Finally, the occurrence frequency of sporadic K layers and their possible link to sporadic E layers are examined.

  6. Space Shuttle Impacts on Mesospheric Clouds and Iron Layers as Observed by Lidars and Satellites in the Antarctic and Arctic

    NASA Astrophysics Data System (ADS)

    Chu, X.; Collins, R. L.; Stevens, M. H.; Plane, J. M.; Meier, R. R.; Deland, M. T.; Kelley, M. C.; Nicolls, M. J.; Thurairajah, B.; Varney, R. H.; Mizutani, K.; Yu, Z.

    2009-12-01

    Meteoric iron layers and mesospheric clouds are two layered phenomena that have been used as tracers to study the global thermal and dynamic structures in the mesosphere and lower thermosphere. In January 2003, three days after the Columbia Space Shuttle was launched from the Kennedy Space Center, an iron (Fe) Boltzmann lidar detected strong sporadic Fe layers in the altitude range from 105 to 115 km at Rothera (67.5 S, 68.0 W), Antarctica. Located ~20 km above the peak of meteoric iron layers (near 90 km), these sporadic Fe layers were believed to be from the relocated shuttle exhaust plume and produced by the normal ablation of main engine components during the shuttle launch. This hypothesis was supported by Lyman-alpha observations from the Global Ultraviolet Imager on NASA’s TIMED satellite, showing a major portion of the shuttle plume transported to Antarctica. Enhanced polar mesospheric cloud (PMC) occurrence was observed by the same lidar at Rothera after the shuttle launch, and confirmed by the SBUV data. Such an enhancement of PMC occurrence has been attributed to the large amount of water vapor injected by the shuttle’s main engines near 110 km altitude. Similar phenomena were observed in the Arctic by a resonance Fe lidar and a Rayleigh lidar at Chatanika, Alaska (65 N, 147 W) after the launch of Space Shuttle Endeavor in August 2007. An intense sporadic E layer was co-located with the atom layer indicating a steady state in which iron atoms and ions are in some type of equilibrium. Initial analysis indicates the water vapor plays an important role in the chemistry. In this paper through detailed study of these examples, we demonstrate the impacts of Space Shuttle traffic on the ice mass of mesospheric clouds and on the mesosphere environment.

  7. Ozone in the upper stratosphere and mesosphere

    SciTech Connect

    Prather, M.J.

    1981-06-20

    A detailed photochemical model of the upper stratosphere and mesosphere is compared with three extensive sets of ozone observations: Atmospheric Explorer-E backscattered ultraviolet experiment (BUV), Nimbus-4 BUV, and rocket flights from Wallops Flight Center (ROCOZ). The Nimbus-4 and rocket observations are most sensitive to ozone between 30 and 50 km, whereas observations from AE-E measure the abundance of ozone up to 70 km. The photochemical model accurately reproduces the observed relationship between BUV intensity and local solar zenith angle, although the absolute calibration on AE-E appears to be in error. The AE-E observations and the model both exhibit a morning-afternoon asymmetry, with more ozone in the morning owing to the build up of HO/sub x/ species in the afternoon. Seasonal changes in atmospheric temperature produce an annual maximum in tropical mesospheric ozone during June-July-August. The amplitude of the observed effect is somewhat larger than calculated by the model. Some problems appear to remain with the presently accepted kinetic rates for HO/sub x/ species in the atmosphere. 71 references, 19 figures, 6 tables.

  8. Mesospheric heating due to intense tropospheric convection

    NASA Technical Reports Server (NTRS)

    Taylor, L. L.

    1979-01-01

    A series of rocket measurements made twice daily at Wallops Island, Va., revealed a rapid heating of the mesosphere on the order of 10 K on days when thunderstorms or squall lines were in the area. This heating is explained as the result of frictional dissipation of vertically propagating internal gravity waves generated by intense tropospheric convection. Ray-tracing theory is used to determine the spectrum of gravity wave groups that actually reach mesospheric heights. This knowledge is used in an equation describing the spectral energy density of a penetrative convective element to calculate the fraction of the total energy initially available to excite those waves that do reach the level of heating. This value, converted into a vertical velocity, is used as the lower boundary condition for a multilayer model used to determine the detailed structure of the vertically propagating waves. The amount of frictional dissipation produced by the waves is calculated from the solutions of the frictionless model by use of a vertically varying eddy viscosity coefficient. The heating produced by the dissipation is then calculated from the thermodynamic equation.

  9. UV-screening Organic Matter (CDOM and MAA) as indicators for monitoring changes of the polar marine ecosystem

    NASA Astrophysics Data System (ADS)

    PARK, M. O.; Kang, S. H.; Ha, S. Y.

    2014-12-01

    At Kongsfjorden bay, DOC, CDOM, FDOM, composition of phytoplankton and MAAs were measured from seawater. The relationship between CDOM, DOC vs Chl a was also investigated. DOC of seawater in 2010 and 2011 was increased 68% and 34% respectively in average compared to DOC in 2009. CDOM was in the range of acdom(375): 0.1855 m-1 ~ 0.0965 m-1, and it showed clear decreasing gradient form inside bay to offshore. CDOM vs DOC and Chl a was inversely related in the study area. Biomass of phytoplankton during 2009~2011 was 0.43~ 0.76 mg/m3 and little change was observed, but the composition and dominant classes have changed. Phaeocystis sp. was rare and diatom and cryptophyte were dominant in the center of bay and coastal area, respectively. 5 different MAAs, shinorine, palythine, mycosporine-glycine, porphyra-334, asterine-330 are identified and separated from Arctic phytoplanktons by HPLC and an unknown MAA was identified from Phaeocystis pouchetti. The spatial distribution pattern of MAAs in the study area was similar with the distribution of Phaeocystis sp. in 2009. The concentration of MAA in 2011 was decreased upto 50% with maximum concentration and seems to related with very low abundance of Phaeocystis sp. in the bay. The results from UV B exposure experiment with Phaeocystis pouchetti. and Porosira glacialis revealed clear discrepancy in the response to carbon uptake rate and photo-inhibition, and also the organic matter from these phytoplankton showed a different photo reactivity. Porosira glacialis, larger than Phaeocystis pouchetti. was more resistant to harmful UV B effect and result of carbon uptake rate using 13C support this tendency. In case Phaeocystis pouchetti becomes the dominant species, it is likely CDOM will be easily degraded and the UV screening effect of seawater will be reduced. acdom(375) 0.14m-1in spring in the arctic was higher than 0.11m-1 in the antarctic at monitoring station. These 3 year monitoring in the arctic Kongsfjorden showed a

  10. Connecting small-scale turbulence to large-scale dynamics in the mesosphere using the Mesosphere-Lower Thermosphere Turbulence Experiment (MTeX)

    NASA Astrophysics Data System (ADS)

    Triplett, C. C.; Collins, R. L.; Lehmacher, G. A.; Barjatya, A.; Fritts, D. C.; Luebken, F. J.; Thurairajah, B.; Harvey, V. L.

    2015-12-01

    The general circulation of the middle and upper atmosphere is determined by waves that form in the lower atmosphere. Large-scale Rossby waves and small-scale gravity waves propagate upward and release their energy in regions of instability such as critical layers. Rossby wave breaking leads to large scale disturbances in the wind and temperature fields known as a sudden stratospheric warming (SSW). These have a great impact on the seasonal weather and climate of the middle atmosphere. SSW events have a particular relationship with gravity waves in the Arctic middle atmosphere. During these events gravity waves reestablish geostrophic balance in the wind field, i.e. the stratospheric polar jet. This return to geostrophic balance, called geostrophic adjustment, generates gravity waves. We used the data from a recent rocket mission, lidar measurements, satellites, and MERRA to understand the coupling of small scale turbulent motions to large scale wave motions in the atmosphere. The Mesosphere-Lower Thermosphere Turbulence Experiment (MTeX) rocket investigation was composed of two rockets launched from Poker Flat Research Range on 25-26 January 2015. MTeX was launched into a mesospheric inversion layer (MIL) giving us a known meteorology. A neutral density sensor that measured turbulence at 20 cm scales flew on both MTeX payloads. Rayleigh lidar measurements of the stratosphere and mesosphere give us the temperature and density structure at kilometer scales characterized the mean environment as well as gravity waves and the MIL. Satellite measurements allow us to characterize the planetary wave activity. MERRA reanalysis gives us a characterization of the winds and planetary waves and their effect on the generation and propagation of waves from scales of tens to thousands of km. The combination of these three data sources and MERRA reanalysis gives us a view of the waves from the synoptic-scale generation and propagation of waves to the small-scale generation of

  11. An Overview of the Impact of Energetic Particle Precipitation on the Mesosphere and Stratosphere

    NASA Technical Reports Server (NTRS)

    Jackman, Charles H.

    2008-01-01

    Energetic precipitating particles (EPPs) can cause significant constituent changes in the polar mesosphere and stratosphere (middle atmosphere) during certain periods. Both protons and electrons can influence the polar middle atmosphere through ionization and dissociation processes. EPPs can enhance HOx (H, OH, HO2) through the formation of positive ions followed by complex ion chemistry and NOx (N, NO, NO2) through the dissociation of molecular nitrogen. The HO, increases can lead to ozone destruction in the mesosphere and upper stratosphere via several catalytic loss cycles. Such middle atmospheric HOx,-caused ozone loss is rather short-lived due to the relatively short lifetime (hours) of the HOx constituents. The HOx,-caused ozone depletion has been observed during several solar proton events (SPEs) in the past 40 years. HOx enhancements due to SPEs were confirmed by observations in the past solar cycle. A number of modeling studies have been undertaken over this time period that show predictions of enhanced HO, accompanied by decreased ozone due to energetic particles. The NO, family has a longer lifetime than the HOx family and can also lead to catalytic ozone destruction. EPP-caused enhancements of the NOx family can affect ozone promptly, if produced in the stratosphere, or subsequently, if produced in the 1ow.er thermosphere or mesosphere and transported to the stratosphere. NOx enhancements due to auroral electrons, medium and high energy electrons, relativistic electron precipitation (REP) events, and SPEs have been measured and/or modeled for decades Only a small number of SPEs (less than 10) in each solar cycle have sufficient flux of high energy protons (greater than 30 MeV) to produce a significant amount of NOx directly in the stratosphere to cause a measurable ozone destruction. Very high energy electrons (greater than 1500 keV) during REP events can also produce NOx directly in the stratosphere, however, the frequency and intensity of these

  12. NOx fluxes from the mesosphere and lower thermosphere and their impact on the middle atmosphere composition

    NASA Astrophysics Data System (ADS)

    Stiller, Gabriele

    NOx production in the mesosphere and lower thermosphere (MLT) due to EEPs and SPEs, its subsequent downward transport within polar winter vortices, and its impact on stratospheric NOy and ozone chemistry is currently in the focus of interest. Various publications suggest a link between solar activity and the MLT NOx production, as well as a link and/or possible feedback between man-made climate change and downward transport mechanisms. An overview on the contributions from the MIPAS/ENVISAT observations to this topic, combined with data from other instruments and 2D- and 3D-CTM and CCM studies, will be presented. Enhanced levels of NOx in the upper stratosphere and lower mesosphere have been found for several winters within polar vortices, and after the Halloween SPE in fall 2003. NOx was subsequently transformed to N2 O and other NOy species, leading, for example, to a secondary upper stratospheric HNO3 maximum. The impact of upper stratospheric enhanced NOx levels on the stratospheric NOy budget, the mechanisms of their transformation to other NOy species, and their effect on stratospheric ozone has been studied. The MIPAS data have been compared to results from several chemical models (CCM and CTMs), some of them including ion cluster chemistry. We will present the MIPAS observations and will analyse the comparisons to the various atmospheric models.

  13. The MATS Satellite Mission - Tomographic Perspectives on the Mesosphere

    NASA Astrophysics Data System (ADS)

    Karlsson, B.; Gumbel, J.

    2015-12-01

    Tomography in combination with space-borne limb imaging opens exciting new ways of probing atmospheric structures. MATS (Mesospheric Airglow/Aerosol Tomography and Spectroscopy) is a new Swedish satellite mission that applies these ideas to the mesosphere. MATS science questions focus on mesospheric wave activity and noctilucent clouds. Primary measurement targets are O2 Atmospheric band dayglow and nightglow in the near infrared (759-767 nm) and sunlight scattered from noctilucent clouds in the ultraviolet (270-300 nm). While tomography provides horizontally and vertically resolved data, spectroscopy allows analysis in terms of mesospheric composition, temperature and cloud properties. This poster introduces instrument and analysis ideas, and discusses scientific perspectives and connections to other missions. MATS is being prepared for a launch in 2018.

  14. Response of neutral mesospheric density to geomagnetic forcing

    NASA Astrophysics Data System (ADS)

    Yi, Wen; Reid, Iain M.; Xue, Xianghui; Younger, Joel P.; Murphy, Damian J.; Chen, Tingdi; Dou, Xiankang

    2017-08-01

    We report an analysis of the neutral mesosphere density response to geomagnetic activity from January 2016 to February 2017 over Antarctica. Neutral mesospheric densities from 85 to 95 km are derived using data from the Davis meteor radar (68.5°S, 77.9°E) and the Microwave Limb Sounder on the Aura satellite. Spectral and Morlet wavelet analyses indicate that a prominent oscillation with a periodicity of 13.5 days is observed in the mesospheric density during the declining phase of solar cycle 24 and is associated with variations in solar wind high-speed streams and recurrent geomagnetic activity. The periodic oscillation in density shows a strong anticorrelation with periodic changes in the auroral electrojet index. These results indicate that a significant decrease in neutral mesospheric density as the geomagnetic activity enhances.

  15. Polarizing matter and antimatter: A new method. The study of a repetitive Stern-Gerlach on stored polarized protons and the spin-splitter experiment: Progress report

    SciTech Connect

    Onel, Y.

    1992-02-01

    Several years ago a self-polarization effect for stored (anti)- protons and ions was investigated theoretically. The effect is based on the well-known Stern-Gerlach effect in gradient fields. The aim of the ongoing measurements at the Indiana University Cyclotron Facility (IUCF) is to verify experimentally the various assumptions on which this effect is based. The final goal is to demonstrate this new polarization effect. The proposed effect could be a powerful tool to produce polarized stored hadron beams both in the low-energy range and at SSC and LHC energies. In this progress report we will describe our progress in three parts: (A) Experimental work at IUCF Cooler Ring; (B) Our extensive computer simulations of the spin stability for the IUCF Cooler Ring; and (C) Theoretical studies.

  16. Upper mesospheric lunar tides over middle and high latitudes during sudden stratospheric warming events

    NASA Astrophysics Data System (ADS)

    Chau, J. L.; Hoffmann, P.; Pedatella, N. M.; Matthias, V.; Stober, G.

    2015-04-01

    In recent years there have been a series of reported ground- and satellite-based observations of lunar tide signatures in the equatorial and low latitude ionosphere/thermosphere around sudden stratospheric warming (SSW) events. This lower atmosphere/ionosphere coupling has been suggested to be via the E region dynamo. In this work we present the results of analyzing 6 years of hourly upper mesospheric winds from specular meteor radars over a midlatitude (54°N) station and a high latitude (69°N) station. Instead of correlating our results with typical definitions of SSWs, we use the definition of polar vortex weaking (PVW) used by Zhang and Forbes. This definition provides a better representation of the strength in middle atmospheric dynamics that should be responsible for the waves propagating to the E region. We have performed a wave decomposition on hourly wind data in 21 day segments, shifted by 1 day. In addition to the radar wind data, the analysis has been applied to simulations from Whole Atmosphere Community Climate Model Extended version and the thermosphere-ionosphere-mesosphere electrodynamics general circulation model. Our results indicate that the semidiurnal lunar tide (M2) enhances in northern hemispheric winter months, over both middle and high latitudes. The time and magnitude of M2 are highly correlated with the time and associated zonal wind of PVW. At middle/high latitudes, M2 in the upper mesosphere occurs after/before the PVW. At both latitudes, the maximum amplitude of M2 is directly proportional to the strength of PVW westward wind. We have found that M2 amplitudes could be comparable to semidiurnal solar tide amplitudes, particularly around PVW and equinoxes. Besides these general results, we have also found peculiarities in some events, particularly at high latitudes. These peculiarities point to the need of considering the longitudinal features of the polar stratosphere and the upper mesosphere and lower thermosphere regions. For

  17. Seasonal variability of mesospheric water vapor

    NASA Technical Reports Server (NTRS)

    Schwartz, P. R.; Bevilacqua, R. M.; Wilson, W. J.; Ricketts, W. B.; Howard, R. J.

    1985-01-01

    Ground-based spectral line measurements of the 22.2 GHz atmospheric water vapor line in emission were made at the JPL in order to obtain data in a dry climate, and to confirm similar measurements made at the Haystack Observatory. The results obtained from March 1984 to July 1984 and from December 1984 to May 1985, were based on data recorded by a HP9816 microcomputer. The instrument spectrometer was a 64 channel, 62.5 kHz resolution filter bank. Data indicates the existence of a seasonal variation in the abundance of water vapor in the upper mesosphere, with mixing ratios higher in summer than in spring. This is consistent with recent theoretical and observational results. In the area of semiannual oscillation, Haystack data are more consistent than those of JPL, indicating an annual cycle with abundances at maximum in summer and minimum in winter.

  18. The stability of the mesospheric plasma layer

    SciTech Connect

    Pandey, B. P.; Vladimirov, S. V.

    2011-12-15

    The presence of micron and sub-micron size dust in the Earth's summer mesopause are a possible cause of electron density depletion. Whereas electrons in this weakly ionized and weakly magnetized layer are frozen in the magnetic field, the ions and dust are highly diffusive. This relative drift between the plasma particles will cause a current in the medium. The presence of such a current can destabilize the plasma layer with a growth rate of the order of Alfven frequency. Since required current density for the onset of this instability is on the order of J > or approx. 0.03A/m{sup 2}, it is quite unlikely that such a strong current is present in the mesosphere. However, owing to the prevailing ambiguity of measurements, the existence of such a current is not completely ruled out.

  19. The effects of dissolved organic matter and pH on sampling rates for polar organic chemical integrative samplers (POCIS).

    PubMed

    Li, Hongxia; Helm, Paul A; Paterson, Gordon; Metcalfe, Chris D

    2011-04-01

    The effect of solution pH and levels of dissolved organic matter (DOM) on the sampling rates for model pharmaceuticals and personal care products (PPCPs) and endocrine disrupting substance (EDS) by polar organic chemical integrative samplers (POCIS) was investigated in laboratory experiments. A commercially available POCIS configuration containing neutral Oasis HLB (hydrophilic-lipophilic balance) resin (i.e. pharmaceutical POCIS) and two POCIS configurations prepared in-house containing MAX and MCX anion and cation exchange resins, respectively were tested for uptake of 21 model PPCPs and EDS, including acidic, phenolic, basic and neutral compounds. Laboratory experiments were conducted with dechlorinated tap water over a pH range of 3, 7 and 9. The effects of DOM were studied using natural water from an oligotrophic lake in Ontario, Canada (i.e. Plastic Lake) spiked with different amounts of DOM (the concentration of dissolved organic carbon ranged from 3 to 5mgL(-1) in uptake experiments). In experiments with the commercial (HLB) POCIS, the MCX-POCIS and the MAX-POCIS, the sampling rates generally increased with pH for basic compounds and declined with pH for acidic compounds. However, the sampling rates were relatively constant across the pH range for phenols with high pKa values (i.e. bisphenol A, estrone, estradiol, triclosan) and for the neutral pharmaceutical, carbamazepine. Thus, uptake was greatest when the amount of the neutral species in solution was maximized relative to the ionized species. Although the solution pH affected the uptake of some model ionic compounds, the effect was by less than a factor of 3. There was no significant effect of DOM on sampling rates from Plastic Lake. However, uptake rates in different aqueous matrixes declined in the order of deionized water>Plastic Lake water>dechlorinated tap water, so other parameters must affect uptake into POCIS, although this influence will be minor. MAX-POCIS and MCX-POCIS showed little advantage

  20. Coordinated Ground-Based and AIM Satellite Measurements of Mesospheric and Stratospheric Waves over South America

    NASA Astrophysics Data System (ADS)

    Taylor, M. J.; Zhao, Y.; Pautet, P. D.; Carstens, J. N.; Pugmire, J. R.; Smith, S. M.; Liu, A. Z.; Vargas, F.; Swenson, G. R.; Randall, C. E.; Bailey, S. M.; Russell, J. M., III

    2016-12-01

    To date, the primary research goals of the Aeronomy of Ice in the Mesosphere (AIM) satellite have focussed on investigating the occurrence, properties and dynamics of high-latitude Polar Mesospheric Clouds (PMC). With the evolution of the AIM orbit beta angle the opportunity now exists to make measurements outside the PMC region covering mid-low and equatorial latitudes. As part of the extended AIM mission science program, the AIM platform in conjunction with auxiliary ground-based measurements will be used to better understand upper atmospheric dynamics and vertical coupling due to gravity waves. Over the next 2 years AIM will take advantage of a new imaging capability of the on-board large-field CIPS UV imager to capture new data on the characteristics and spatial extents of stratospheric gravity waves near the 50 km level and their variation with latitude and season. In this study we report on initial coordinated ground-based measurements with the Andes Lidar Observatory (ALO) at Cerro Pachon, Chile ( 30°S) and nearby El Leoncito Observatory, Argentina, high in the Andes Mountains, where regular remote-sensing measurements are made using meteor radar, mesospheric airglow imagers, temperature mappers and an Na wind-temperature lidar (on a campaign basis). First coordinated measurements were made during the winter period in June 2016. AIM daytime overpasses have been analysed to search for and characterize extensive stratospheric wave events, as well as long-lived "Mountain Waves" over South America. Subsequent night-time ground-based measurements have been used to quantify wave characteristics in the mesopause region ( 80-100 km) to investigate vertical coupling. These measurements are continuing and it is planned to extend the new AIM stratospheric gravity wave data set for similar studies from a number of well-instrumented ground sites around the world.

  1. Observed Seasonal to Decadal-Scale Responses in Mesospheric Water Vapor

    NASA Technical Reports Server (NTRS)

    Remsberg, Ellis

    2010-01-01

    The 14-yr (1991-2005) time series of mesospheric water vapor from the Halogen Occultation Experiment (HALOE) are analyzed using multiple linear regression (MLR) techniques for their6 seasonal and longer-period terms from 45S to 45N. The distribution of annual average water vapor shows a decrease from a maximum of 6.5 ppmv at 0.2 hPa to about 3.2 ppmv at 0.01 hPa, in accord with the effects of the photolysis of water vapor due to the Lyman-flux. The distribution of the semi-annual cycle amplitudes is nearly hemispherically symmetric at the low latitudes, while that of the annual cycles show larger amplitudes in the northern hemisphere. The diagnosed 11-yr, or solar cycle, max minus min, water vapor values are of the order of several percent at 0.2 hPa to about 23% at 0.01 hPa. The solar cycle terms have larger values in the northern than in the southern hemisphere, particularly in the middle mesosphere, and the associated linear trend terms are anomalously large in the same region. Those anomalies are due, at least in part, to the fact that the amplitudes of the seasonal cycles were varying at northern mid latitudes during 1991-2005, while the corresponding seasonal terms of the MLR model do not allow for that possibility. Although the 11-yr variation in water vapor is essentially hemispherically-symmetric and anti-phased with the solar cycle flux near 0.01 hPa, the concurrent temperature variations produce slightly colder conditions at the northern high latitudes at solar minimum. It is concluded that this temperature difference is most likely the reason for the greater occurrence of polar mesospheric clouds at the northern versus the southern high latitudes at solar minimum during the HALOE time period.

  2. Reduced meteoric smoke particle density at the summer pole - implications for mesospheric ice particle nucleation

    NASA Astrophysics Data System (ADS)

    Megner, L.; Gumbel, J.; Rapp, M.; Siskind, D.

    2007-12-01

    Noctilucent clouds (NLC) and polar mesospheric summer echoes (PMSE) are phenomena that occur in the summertime polar regions due to the presence of ice particles around the mesopause. That ice particles are able to form in a region with such low water vapor concentration as the mesopause is noteworthy. Even though the summer mesopause is the coldest region on earth, temperatures are generally not low enough for homogeneous nucleation to occur, which necessitates the presence of pre-existing condensation nuclei. The nature of these nuclei has long puzzled the scientific community and many candidates have been suggested, such as particles of meteoric origin, ion clusters, sodium bi-carbonate, sulfate aerosols and soot particles. Out of these the so called "smoke particles", i. e. particles re-condensed from ablated meteoritic material, have long been considered the most likely. Generally, it has been believed that these particles exist in numbers of the order of thousands per cubic centimeter at the mesopause. This belief is based on 1-dimensional studies of meteoric material. A recent 2-dimensional model study, which includes the atmospheric circulation from summer to winter pole however, suggests much lower number densities at the summer mesopause. We here investigate the implications of low number densities for the formation of ice particles. We find that even though resulting ice particle distribution may produce typical NLC brightness, the number density of ice particles is not consistent with what is expected for NLC and PMSE. In particular, it is much lower than the ice particle concentration (>1000 cm-3) typically expected to explain the "electron bite-outs" that are frequently observed in the vicinity of PMSE's. We therefore re-examine the assumptions and parameters that determine the smoke distribution. We show that even though the number of condensation nuclei at the polar summer mesopause can be increased within the uncertainties, the results in most

  3. Retrieving mesospheric water vapour from observations of volume scattering radiances

    NASA Astrophysics Data System (ADS)

    Vergados, P.; Shepherd, M. G.

    2009-02-01

    This study examines the possibility for a theoretical approach in the estimation of water vapour mixing ratios in the vicinity of polar mesospheric clouds (PMC) using satellite observations of Volume Scattering Radiances (VSR) obtained at the wavelength of 553 nm. The PMC scattering properties perturb the underlying molecular Rayleigh scattered solar radiance of the background atmosphere. As a result, the presence of PMC leads to an enhancement in the observed VSR at the altitude of the layer; the PMC VSRs are superimposed on the exponentially decreasing with height Rayleigh VSR, of the PMC-free atmosphere. The ratio between the observed and the Rayleigh VSR of the background atmosphere is used to simulate the environment in which the cloud layer is formed. In addition, a microphysical model of ice particle formation is employed to predict the PMC VSRs. The initial water vapour profile is perturbed until the modelled VSRs match the observed, at which point the corresponding temperature and water vapour profiles can be considered as a first approximation of those describing the atmosphere at the time of the observations. The role of temperature and water vapour in the cloud formation is examined by a number of sensitivity tests suggesting that the water vapour plays a dominant role in the cloud formation in agreement with experimental results. The estimated water vapour profiles are compared with independent observations to examine the model capability in the context of this study. The results obtained are in a good agreement at the peak of the PMC layer although the radiance rapidly decreases with height below the peak. This simplified scenario indicates that the technique employed can give a first approximation estimate of the water vapour mixing ratio, giving rise to the VSR observed in the presence of PMC.

  4. First detection of charged dust particles in the Earth's mesosphere

    NASA Astrophysics Data System (ADS)

    Havnes, O.; Trøim, J.; Blix, T.; Mortensen, W.; Næsheim, L. I.; Thrane, E.; Tønnesen, T.

    1996-05-01

    Some theories for the observed anomalous radar backscatter during the summer (polar mesospheric summer echoes, or PMSE) and electron bite outs measured by rockets require the presence of charged dust. To investigate this, two dust probes have been launched in 1994 from Andyøa Rocket Range and we here report the results from the dust and an electron probe on the two payloads. The dust probes were designed to block out the electron and ion components at the mesopause but to detect primary currents due to impacts of charged dust and also to detect secondary plasma production during dust impacts. The results indicate that both during PMSE and noctilucent cloud (NLC) conditions, large amounts of dust, with average sizes apparently of about 0.1 μm and less, were present. The number densities Nd can be up to many thousand per cubic centimeter, and the charge density NdZd likewise. Large local gradients in density and charge density of dust are detected. Dust carrying both positive and negative charges can apparently be present on different occasions. In some parts of the NLC/PMSE layers we find that the negative charge density locked in grains is so large that the number of free electrons is significantly reduced there because the dust acts like sinks for electrons, and an electron bite out results. We also find that in one case the presence of positive dust leads to an increase in the local electron density by photoionization. The main uncertainties in the data analysis are the structure of the dust and the secondary plasma production at the comparatively low dust impact velocities (1 kms-1) in the experiment.

  5. First results from the Spatial Heterodyne Imager for Mesospheric Radicals (SHIMMER): Diurnal variation of mesospheric hydroxyl

    NASA Astrophysics Data System (ADS)

    Englert, Christoph R.; Stevens, Michael H.; Siskind, David E.; Harlander, John M.; Roesler, Fred L.; Pickett, Herbert M.; von Savigny, Christian; Kochenash, Andrew J.

    2008-10-01

    We present the first SHIMMER observations of the diurnal variation of mesospheric hydroxyl (OH). We compare our data with Aura Microwave Limb Sounder (MLS) observations at about 13h local time near 55°N and find very good agreement. This validates the Spatial Heterodyne Spectroscopy technique for space-borne optical remote sensing applications. We extend our analysis to other local times, not observed by MLS, for latitudes near 55°N in the summer of 2007. At 74 km, we find excellent agreement with a photochemical model, but above 76 km, significant model/data differences in the shape of the OH diurnal variation are observed.

  6. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Spin-Polarized Carriers Injection from Ferromagnetic Metal into Organic Semiconductor

    NASA Astrophysics Data System (ADS)

    Qiao, Shi-Zhu; Zhao, Jun-Qing; Jia, Zhen-Feng; Zhang, Tian-You

    2010-10-01

    Charge carriers in organic semiconductor are different from that of traditional inorganic semiconductor. Based on three-current model, considering electrical field effect, we present a theoretical model to discuss spin-polarized injection from ferromagnetic electrode into organic semiconductor by analyzing electrochemical potential both in ferromagnetic electrode and organic semiconductors. The calculated result of this model shows effects of electrode's spin polarization, equilibrium value of polarons ratio, interfacial conductance, bulk conductivity of materials and electrical field. It is found that we could get decent spin polarization with common ferromagnetic electrode by increasing equilibrium value of polarons ratio. We also find that large and matched bulk conductivity of organic semiconductor and electrode, small spin-dependent interfacial conductance, and enough large electrical field are critical factors for increasing spin polarization.

  7. Heterogeneous nucleation and growth of water vapor on meteoric smoke particle analogues at mesospheric conditions

    NASA Astrophysics Data System (ADS)

    Nachbar, Mario; Duft, Denis; Leisner, Thomas

    2016-04-01

    Sub 2 nm meteoric smoke particles (MSP) produced from the ablation and recondensation of meteoric material are believed to be the major kind of nuclei causing the formation of water ice particles in the mesopause of Earth at heights of 80-90 km. These so called noctiLucent clouds (NLC) are frequently detected during polar summer, whereas the microphysical nucleation process and subsequent growth on such small particles are understood only poorly. Parameterizing these processes results in large uncertainties especially due to a lack of experimental data on desorption energies and critical saturation for the activation of nucleation under realistic mesospheric conditions, which states the need of laboratory measurements. We produce charged nanometer sized (2-3 nm) MSP analogues in a microwave plasma particle source and transfer them to a novel linear ion trap which allows us to trap the particles under typical mesospheric temperatures and H2O concentrations. The adsorption of H2O molecules on the particles surface followed by nucleation and growth can be examined by analyzing the mass distribution of the particles with a time-of-flight mass spectrometer as function of the residence time under supersaturated conditions. In this contribution we present such measurements for single positively as well as negatively charged particles which allow us to determine the desorption energy of water vapor on the investigated nanoparticles as well as the critical saturation needed to activate nucleation and subsequent growth.

  8. Secondary gravity waves in the winter mesosphere: Results from a high-resolution global circulation model

    NASA Astrophysics Data System (ADS)

    Becker, Erich; Vadas, Sharon

    2017-04-01

    General circulation models that simulate gravity waves (GWs) explicitly are expected to capture the spatial and temporal variability of the GW sources. Moreover, secondary GWs that result from the nonlinearity and intermittency of the primary GWs in the middle atmosphere can be studied. In this study we describe a new high-resolution version of the Kuehlungsborn Mechanistic general Circulation Model (KMCM). The model includes no GW parameterization, and unresolved dynamical scales are parameterized by a macro-turbulent diffusion scheme that accounts for damping of resolved waves in a self-consistent fashion. We analyze the model with regard to secondary GWs in the mesosphere during Austral winter. The westward GW drag in the lower winter mesosphere agrees well with that from conventional models with parameterized GWs, and it is strongly due to orographic GWs generated by the Andes and the Antartic Pensiula. Due to the high temporal and spatial intermittency of the primary GWs in the southern winter stratopause region, secondary GWs are generated and propagate to higher altitudes. These secondary GWs impose a substantial eastward drag in the mesopause region where they dissipate. The eastward GW drag results in an additional eastward maximum of the mean zonal wind around 90-100 km. We propose that when the polar night jet is strong, secondary GWs may play a significant role in the general circulation of the winter mesopause region. Radar measurements in the northern hemisphere during January 2016 are consistent with this finding.

  9. Analysis of charged aerosols in the mesosphere during the MASS/ECOMA rocket campaign

    NASA Astrophysics Data System (ADS)

    Knappmiller, Scott Robert

    In the polar summer mesosphere ice particles grow sufficiently large to scatter sunlight, giving rise to visible cloud displays called Noctilucent Clouds (NLC). In August of 2007, two sounding rockets were launched from the Andoya Rocket Range, Norway carrying the newly developed MASS instrument (Mesospheric Aerosol Sampling Spectrometer) to study NLC. The instrument detects charged aerosols in four different mass ranges on four pairs of biased collector plates, one set for positive particles and one set for negative particles. The first sounding rocket was launched into a Polar Mesospheric Summer echo (PMSE) and into a NLC on 3 August. The solar zenith angle was 93 degrees and NLC were seen in the previous hour at 83 km by the ALOMAR RMR lidar. NLC were also detected at the same altitude by rocket-borne photometer measurements. The data from the MASS instrument shows a negatively charged population with radii >3 nm in the 83--89 km altitude range, which is collocated with PMSE detected by the ALWIN radar. Smaller particles, 1--2 nm in radius with both positive and negative polarity were detected between 86--88 km. Positively charged particles <1 nm in radius were detected at the same altitude. This is the first time the charge number densities of positive and negative NLC particles have been measured simultaneously. A charging model is developed to investigate the coexistence of positively and negatively charged aerosols in the NLC environment as measured by the MASS instrument. Natanson's rate equations are used for the attachment of free electrons and ions and the model includes charging by photo-electron emission and photo-detachment. Although the MASS flight occurred during twilight conditions, the solar UV flux was still sufficient to affect the charge state of the aerosols. The calculations are done assuming three types of particles with different photo-electron charging properties: (1) Icy NLC particles, (2) Hematite particles of meteoric origin as

  10. Advanced mesospheric temperature mapper for high-latitude airglow studies.

    PubMed

    Pautet, P-D; Taylor, M J; Pendleton, W R; Zhao, Y; Yuan, T; Esplin, R; McLain, D

    2014-09-10

    Over the past 60 years, ground-based remote sensing measurements of the Earth's mesospheric temperature have been performed using the nighttime hydroxyl (OH) emission, which originates at an altitude of ∼87  km. Several types of instruments have been employed to date: spectrometers, Fabry-Perot or Michelson interferometers, scanning-radiometers, and more recently temperature mappers. Most of them measure the mesospheric temperature in a few sample directions and/or with a limited temporal resolution, restricting their research capabilities to the investigation of larger-scale perturbations such as inertial waves, tides, or planetary waves. The Advanced Mesospheric Temperature Mapper (AMTM) is a novel infrared digital imaging system that measures selected emission lines in the mesospheric OH (3,1) band (at ∼1.5  μm) to create intensity and temperature maps of the mesosphere around 87 km. The data are obtained with an unprecedented spatial (∼0.5  km) and temporal (typically 30″) resolution over a large 120° field of view, allowing detailed measurements of wave propagation and dissipation at the ∼87  km level, even in the presence of strong aurora or under full moon conditions. This paper describes the AMTM characteristics, compares measured temperatures with values obtained by a collocated Na lidar instrument, and presents several examples of temperature maps and nightly keogram representations to illustrate the excellent capabilities of this new instrument.

  11. Mesospheric Temperature Inversion Layers: Recent Observations from UARS ISAMS and MLS

    NASA Technical Reports Server (NTRS)

    Wu, D.

    1999-01-01

    This paper presents an observational study of the mesospheric temperature inversion layer with Upper Atmosphere Research Satellite (UARS) Improved Stratospheric and Mesospheric Sounder (ISAMS) and Microwave Limb Sounder (MLS). The satellite data show that the temperature inversion layer can be generated from deep penetration of planetary waves in the mesosphere.

  12. Mesospheric wave number spectra from Poker Flat MST radar measurements compared with gravity-wave model

    NASA Technical Reports Server (NTRS)

    Smith, S. A.; Fritts, D. C.; Vanzandt, T. E.

    1986-01-01

    The results of a comparison of mesospheric wind fluctuation spectra computed from radial wind velocity estimates made by the Poker Flat mesosphere-stratosphere-troposphere (MST) radar are compared with a gravity-wave model developed by VanZandt (1982, 1985). The principal conclusion of this comparison is that gravity waves can account for 80% of the mesospheric power spectral density.

  13. Mesospheric ozone measurements by SAGE II

    NASA Technical Reports Server (NTRS)

    Chu, D. A.; Cunnold, D. M.

    1994-01-01

    SAGE II observations of ozone at sunrise and sunset (solar zenith angle = 90 deg) at approximately the same tropical latitude and on the same day exhibit larger concentrations at sunrise than at sunset between 55 and 65 km. Because of the rapid conversion between atomic oxygen and ozone, the onion-peeling scheme used in SAGE II retrievals, which is based on an assumption of constant ozone, is invalid. A one-dimensional photochemical model is used to simulate the diurnal variation of ozone particularly within the solar zenith angle of 80 deg - 100 deg. This model indicates that the retrieved SAGE II sunrise and sunset ozone values are both overestimated. The Chapman reactions produce an adequate simulation of the ozone sunrise/sunset ratio only below 60 km, while above 60 km this ratio is highly affected by the odd oxygen loss due to odd hydrogen reactions, particularly OH. The SAGE II ozone measurements are in excellent agreement with model results to which an onion peeling procedure is applied. The SAGE II ozone observations provide information on the mesospheric chemistry not only through the ozone profile averages but also from the sunrise/sunset ratio.

  14. An experimental investigation of mesospheric ionization

    NASA Technical Reports Server (NTRS)

    Mitchell, J. D.

    1973-01-01

    Mesospheric ionization and its variability are examined. Data were obtained primarily by the parachute-borne blunt probe technique conducted in coordinated rocket experiments at White Sands Missile Range, New Mexico and Wallops Island, Virginia. Electrical conductivity measurements and deduced charge density values from ten rocket launches are presented and discussed. Positive ion conductivity and electron density were found to be relatively invariant with height between 45 and 60 km. Variations in positive conductivity of a factor of two and enhancements in negative conductivity by as much as a factor of four were measured by the blunt probe. A simple lumped parameter ion chemistry model is shown to satisfactorily explain the charge density values for the undisturbed lower D-region. Implications of the data in terms of this model are considered. The principal loss mechanism for positive ions in the 45 to 60 km. region is concluded to be dissociative recombination. Electron densities deduced from the conductivity data are explained by detachment involving a minor neutral constituent which is mixed between 65 and 45 km. and then cuts off sharply below 45 km. A correlation study involving blunt probe measurements shows relatively good agreement between variations in positive conductivity and temperature.

  15. Observations of mesosphere summer echoes with calibrated VHF radars at latitudes between 54°N and 69°N in summer 2004

    NASA Astrophysics Data System (ADS)

    Latteck, R.; Singer, W.; Kirkwood, S.; Jönsson, L. O.; Eriksson, Håkan

    2005-08-01

    Mesosphere Summer Echoes (MSE) have been observed with 50-MHz VHF radars at middle (MSE) and polar latitudes (PMSE) for more than 20 years. The occurrence and seasonal variation of these radar echoes as well as their dependence on solar and geomagnetic activity are mostly studied basing on relative signal strength measurements (signal-to-noise ratios). The latitudinal dependence of the appearance and intensity of mesospheric summer echoes is still an open question as the widely used relative signal strength observations are determined by the atmospheric properties as well as by the individual radar characteristics. The use of absolutely calibrated echo powers allows a system in-depended comparison of mesospheric summer echoes observed at different sites by different systems. We present two different radar calibration methods. One applies a noise source to calibrate the receive path of the radar only, a second uses the radar signal itself to calibrate the complete transmitting and receiving path of the radar system. Both techniques and the same calibration hardware have been applied to the ALWIN VHF radar at Andenes/Norway (69°N), the ESRAD radar at Kiruna/Sweden (68deg;N) and OSWIN radar at Kühlungsborn/Germany (54°N). The sensitivity of the different radar systems and the seasonal and diurnal variation of the occurrence of mesospheric summer echoes at different locations are discussed on the basis of radar backscatter cross-sections.

  16. The MATS satellite mission - tomographic perspectives on the mesosphere

    NASA Astrophysics Data System (ADS)

    Christensen, Ole Martin; Gumbel, Jörg; Megner, Linda; Murtagh, Donal P.; Ivchenko, Nickolay

    2016-04-01

    MATS (Mesospheric Airglow/Aerosol Tomography and Spectroscopy) is a Swedish satellite mission scheduled for launch in 2019. MATS science focuses on mesospheric wave activity and noctilucent clouds. Primary measurement targets are O2 Atmospheric band dayglow and nightglow in the near infrared (759-767 nm) and sunlight scattered from noctilucent clouds in the ultraviolet (270-300 nm). While tomography provides horizontally and vertically resolved data, spectroscopy allows analysis in terms of mesospheric composition, temperature and cloud properties. During 2015, the design of the MATS instrument was finalized, and the first complete instrument design will be shown in this presentation. As a part of this work, simulated measurements were performed and inverted using a 3 dimensional tomographic algorithm based on the optimal estimation method. As a result, the first quantitative estimation of the instruments capabilities and performance figures can now be presented, and hence give a more accurate picture of the scientific opportunities that the MATS mission provides.

  17. Experimental evidence of a stratospheric circulation influence on mesospheric temperatures and ice-particles during the 2010-2011 austral summer at 69°S

    NASA Astrophysics Data System (ADS)

    Morris, Ray J.; Höffner, Josef; Lübken, Franz-Josef; Viehl, Timo P.; Kaifler, Bernd; Klekociuk, Andrew R.

    2012-11-01

    A significant inter-annual decrease in polar mesosphere ice-particles, i.e., PMSE and PMC, during 2010-2011 is compared with earlier austral summers, in particular with 2009-2010. The first IAP iron lidar temperature measurement at Davis (68.6°S), Antarctica from 14 December 2010 are used to assess thermal effects of atmospheric processes on the mesopause region. We report low average temperatures of ˜125 K measured by Fe-lidar near 90 km when the PMSE season commenced, whereas temperatures were warmer in 2010-2011 compared to 2009-2010 at altitudes where PMSE normally occur (around 86 km). Summer mesopause region temperature anomalies are derived using Aura MLS records. We reveal that the late break-down of the Antarctic stratospheric polar vortex on 5 January 2010, coupled with enhanced early summer mesospheric zonal wind field, provide a barrier to upward propagation of atmospheric gravity waves to be the main mechanism for the observed warm early summer season below the mesopause. The mesopause in 2010-2011 was unusually high and cold. We conclude that the timing of the annual break-down of the southern polar stratospheric vortex as manifest in zonal winds at 30 hPa impacts mesosphere temperature and ice-particle formation early in the austral summer.

  18. Solar Mesosphere Explorer optical-mechanical systems engineering

    NASA Technical Reports Server (NTRS)

    Gause, K. A.; Stuart, J. R.

    1979-01-01

    Mission overview of the Solar Mesosphere Explorer is presented along with design analysis and summaries of results. The Solar Mesosphere Explorer is a spin stabilized satellite carrying a complement of four Ebert-Fastie spectrometers and a four-channel Mersenne radiometer. Description of the spectrometer is given including a telescope and its aberrations. The radiometer is also described with consideration given to isothermal and thermal design, a Winston paraboloid, and optical tolerances. These five instruments are for measuring the earth's ozone density and distribution and providing quantitative data about those processes which govern the formation and destruction of ozone.

  19. Resonance lidar detection of the mesospheric nickel layer

    NASA Astrophysics Data System (ADS)

    Martus, C. M.; Collins, R. L.

    2013-12-01

    We present the first reported detection of the mesospheric nickel (Ni) layer with resonance lidar. Ni is abundant in meteorites, the source of the metal layers, but has not been previously detected in the mesosphere. We detail the wavelength search we used to find the Ni absorption line and the SNR technique we used to extract the low resonance signal. Simulation results based on measurements of sodium (Na) with our system show that the signals received are as expected. We present an initial estimate of the Ni layer density and spatial parameters and find that the Ni layer characteristics are similar to those of the sodium layer.

  20. Solar Mesosphere Explorer optical-mechanical systems engineering

    NASA Technical Reports Server (NTRS)

    Gause, K. A.; Stuart, J. R.

    1979-01-01

    Mission overview of the Solar Mesosphere Explorer is presented along with design analysis and summaries of results. The Solar Mesosphere Explorer is a spin stabilized satellite carrying a complement of four Ebert-Fastie spectrometers and a four-channel Mersenne radiometer. Description of the spectrometer is given including a telescope and its aberrations. The radiometer is also described with consideration given to isothermal and thermal design, a Winston paraboloid, and optical tolerances. These five instruments are for measuring the earth's ozone density and distribution and providing quantitative data about those processes which govern the formation and destruction of ozone.

  1. Mesospheric electron detachment and LORE recovery times

    NASA Astrophysics Data System (ADS)

    Gordillo-Vazquez, Francisco J.; Haldoupis, Christos; Luque, Alejandro

    2015-04-01

    We present new results concerning the recovery times (> 10 minutes) of LOng Recovery Early VLF events (LORE) in the upper mesosphere connected to electromagnetic pulses (EMP) of large (> 250 kA km) charge moment change (CMC) ± CG (cloud to ground) lightning capable of producing elves or elve-sprite pairs (in the case of +CG parent lightning) [1], [2]. We have modeled two possible scenarios considering first the relaxation of slightly perturbed ambient electron densities (ne0 + Δne) without an impulsive ionization source and another scenario where the ambient electron density is considerably enhanced due to an impulsive ionization source (the lightning EMP). The full non-equilibrium kinetic and 2D EMP modelling of the perturbed mesosphere in the 76 km - 92 km range during LORE occurring conditions indicates that the electron density relaxation time (defined as the time the perturbed electron density, Δne, takes to decay a factor 1/e of the way to the ambient electron density (ne0)) is critically controlled at each altitude by the relative importance of associative detachment (of O- by, respectively, O and CO and of O2- by O) with respect to electron loss mechanisms (mainly 3-body, 2-body attachment and electron-ion recombination at the highest altitudes). We found that the maximum electron density relaxation time (> 15000 s) occur between 80 km and 82 km while it decreases with increasing altitudes to 12000 s (at 85 km) and about 2000 s (at 92 km). However, LORES are presumably due to VLF scattering from electron density enhancements caused by lightning-induced EMPs in the uppermost D region ionosphere (85 - 92 km). Thus the observed VLF signal recoveries (LORE recovery times) should associate with the relaxation of the maximum enhanced electron densities produced by elves between 85 km and 92 km [3]. Finally, our results for the lowest altitudes considered (76 km and 77 km) are in good agreement with the recovery times (between 20 s and 120 s) of the typical

  2. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Controllable Spin Polarization of Charge Current by Rashba Spin Orbital Coupling

    NASA Astrophysics Data System (ADS)

    Cui, Juan; Yang, Yong-Hong; Wang, Jun

    2009-11-01

    We report a theoretic study on modulating the spin polarization of charge current in a mesoscopic four-terminal device of cross structure by using the inverse spin hall effect. The scattering region of device is a two-dimensional electron gas (2DEG) with Rashba spin orbital interaction (RSOI), one of lead is ferromagnetic metal and other three leads are spin-degenerate normal metals. By using Landauer-Büttiker formalism, we found that when a longitudinal charge current flows through 2DEG scattering region from FM lead by external bias, the transverse current can be either a pure spin current or full-polarized charge current due to the combined effect of spin hall effect and its inverse process, and the polarization of this transverse current can be easily controlled by several device parameters such as the Fermi energy, ferromagnetic magnetization, and the RSOI constant. Our method may pave a new way to control the spin polarization of a charge current.

  3. Short-period mesospheric gravity waves and their sources at the South Pole

    NASA Astrophysics Data System (ADS)

    Mehta, Dhvanit; Gerrard, Andrew J.; Ebihara, Yusuke; Weatherwax, Allan T.; Lanzerotti, Louis J.

    2017-01-01

    The sourcing locations and mechanisms for short-period, upward-propagating gravity waves at high polar latitudes remain largely unknown. Using all-sky imager data from the Amundsen-Scott South Pole Station, we determine the spatial and temporal characteristics of 94 observed small-scale waves in 3 austral winter months in 2003 and 2004. These data, together with background atmospheres from synoptic and/or climatological empirical models, are used to model gravity wave propagation from the polar mesosphere to each wave's source using a ray-tracing model. Our results provide a compelling case that a significant proportion of the observed waves are launched in several discrete layers in the tropopause and/or stratosphere. Analyses of synoptic geopotentials and temperatures indicate that wave formation is a result of baroclinic instability processes in the stratosphere and the interaction of planetary waves with the background wind fields in the tropopause. These results are significant for defining the influences of the polar vortex on the production of these small-scale, upward-propagating gravity waves at the highest polar latitudes.

  4. Electrical structure and E-fields in the high-latitude mesosphere

    NASA Technical Reports Server (NTRS)

    Mitchell, John D.; Walter, Deborah J.; Croskey, Charles L.; Goldberg, Richard A.

    1995-01-01

    A description of the electric structure as observed during a rocket sounding noctilucent cloud (NLC) observation program in the summer of 1991, is presented. Both NLC and polar mesosphere summer echo (PMSE) conditions were determined. The observable effects on ions and electrons were measured in the NLC and PMSE regions and associated electric field (E-fields) measurements indicated small alternating current vertical fields. The following findings are reported: small and large scale electron density structure is noticeable in the NLC regions; above 82 km, the occurrence of very low-mobility positive ions directly demonstrates the existence of charged aerosols, and small alternating current vertical electric fields were observed in the NLC and PMSE region.

  5. Electrical structure and E-fields in the high-latitude mesosphere

    NASA Technical Reports Server (NTRS)

    Mitchell, John D.; Walter, Deborah J.; Croskey, Charles L.; Goldberg, Richard A.

    1995-01-01

    A description of the electric structure as observed during a rocket sounding noctilucent cloud (NLC) observation program in the summer of 1991, is presented. Both NLC and polar mesosphere summer echo (PMSE) conditions were determined. The observable effects on ions and electrons were measured in the NLC and PMSE regions and associated electric field (E-fields) measurements indicated small alternating current vertical fields. The following findings are reported: small and large scale electron density structure is noticeable in the NLC regions; above 82 km, the occurrence of very low-mobility positive ions directly demonstrates the existence of charged aerosols, and small alternating current vertical electric fields were observed in the NLC and PMSE region.

  6. Model of Semidiurnal Pseudo Tide in the High-Latitude Upper Mesosphere

    NASA Technical Reports Server (NTRS)

    Talaat, E. R.; Mayr, H. G.

    2011-01-01

    We present numerical results for the m = 1 meridional winds of semi diurnal oscillations in the high-latitude upper mesosphere, which are generated in the Numerical Spectral Model (NSM) without solar excitations of the tides. Identified with heuristic computer runs, the pseudo tides attain amplitudes that are, at times, as large as the non-migrating tides produced with standard solar forcing. Under the influence of parameterized gravity waves, the nonlinear NSM generates internal oscillations like the quasi-biennial oscillation, that are produced with periods favored by the dynamical properties of the system. The Coriolis force would favor at polar latitudes the excitation of the 12-hour periodicity. This oscillation may help explain the large non-migrating semidiurnal tides that are observed in the region with ground-based and satellite measurements.

  7. Metals in the mesosphere: chemistry and change

    NASA Astrophysics Data System (ADS)

    Plane, John; Marsh, Daniel; Höffner, Josef; Janches, Diego; Dawkins, Erin; Gomez-Martin, Juan Carlos; Bones, David; Feng, Wuhu; Chipperfield, Martyn

    2016-07-01

    The meteoric metal layers (e.g. Na, Fe, K and Ca) - which form as a result of the ablation of incoming meteors - act as unique tracers for chemical and dynamical processes that occur within the upper mesosphere/lower thermosphere region. This presentation examines whether these metal layers are sensitive indicators of longer-term changes within the upper atmosphere. Output from the Whole Atmosphere Community Climate Model (WACCM) is used to assess the response of the Na, K and Fe layers across a 50-year period (1955-2005), while both model and observational data (satellite and lidar) is used to assess the response of the Na and K layers to the 11-year solar cycle extending between 2004-2013. On short time-scales, the K layer exhibits a very different seasonal behaviour compared to the other metals. This unusual behaviour is also exhibited at longer time-scales (both the 11-yr solar cycle and 50-yr periods); K displays a much more pronounced response to atmospheric changes at a 50-yr time scale than either Na or Fe. Underpinning this modelling work are two new laboratory systems developed at Leeds. First, a time-of-flight mass spectrometer with laser photo-ionization has been used to study the reactions of neutral metallic compounds in the gas phase which are not detectable by conventional spectroscopic probes. This has enabled significant advances in Na layer chemistry to be made. The second is a flowing afterglow/laser ablation experiment which has been used to study the dissociative recombination of metallic ions such as FeO ^{+} and CaO ^{+} with electrons; these processes are particularly important for modelling the phenomenon of sporadic metal layers.

  8. Revised Correlation between Odin/OSIRIS PMC Properties and Coincident TIMED/SABER Mesospheric Temperatures

    NASA Technical Reports Server (NTRS)

    Feofilov, A. G.; Petelina, S. V.; Kutepov, A. A.; Pesnell, W. D.; Goldberg, R. A.; Llewellyn, E. J.; Russell, J. M.

    2006-01-01

    The Optical Spectrograph and Infrared Imaging System (OSIRIS) instrument on board the Odin satellite detects Polar Mesospheric Clouds (PMCs) through the enhancement in the limb-scattered solar radiance. The Sounding of the Atmosphere using the Broadband Emission Radiometry (SABER) instrument on board the TIMED satellite is a limb scanning infrared radiometer that measures temperature and vertical profiles and energetic parameters for minor constituents in the mesosphere and lower thermosphere. The combination of OSIRIS and SABER data has been previously used to statistically derive thermal conditions for PMC existence [Petelina et al., 2005]. a, A.A. Kutepov, W.D. Pesnell, In this work, we employ the simultaneous common volume measurements of PMCs by OSIRIS and temperature profiles measured by SABER for the Northern Hemisphere summers of 2002-2005 and corrected in the polar region by accounting for the vibrational-vibrational energy exchange among the CO2 isotopes [Kutepov et al., 2006]. For each of 20 coincidences identified within plus or minus 1 degree latitude, plus or minus 2 degrees longitude and less than 1 hour time the frost point temperatures were calculated using the corresponding SABER temperature profile and water vapor densities of 1,3, and 10 ppmv. We found that the PMC presence and brightness correlated only with the temperature threshold that corresponds to the frost point. The absolute value of the temperature below the frost point, however, didn't play a significant role in the intensity of PMC signal for the majority of selected coincidences. The presence of several bright clouds at temperatures above the frost point is obviously related to the limitation of the limb geometry when some near- or far-field PMCs located at higher (and warmer) altitudes appear to be at lower altitudes.

  9. Revised Correlation between Odin/OSIRIS PMC Properties and Coincident TIMED/SABER Mesospheric Temperatures

    NASA Technical Reports Server (NTRS)

    Feofilov, A. G.; Petelina, S V.; Kutepov, A. A.; Pesnell, W. D.; Goldberg, R. A.; Llewellyn, E. J.; Russell, J. M.

    2006-01-01

    The Optical Spectrograph and Infrared Imaging System (OSIRIS) instrument on board the Odin satellite detects Polar Mesospheric Clouds (PMCs) through the enhancement in the limb scattered solar radiance. The Sounding of the Atmosphere using the Broadband Emission Radiometry (SABER) instrument on board the TIMED satellite is a limb scanning infrared radiometer that measures temperature and vertical profiles and energetic parameters for minor constituents in the mesosphere and lower thermosphere. The combination of OSIRIS and SABER data has been previously used to statistically derive thermal conditions for PMC existence [Petelina et al., 2005]. In this work, we employ the simultaneous common volume measurements of PMCs by OSIRIS and temperature profiles measured by SABER for the Northern Hemisphere summers of 2002-2005 and corrected in the polar region by accounting for the vibrational-vibrational energy exchange among the CO2 isotopes [Kutepov et al., 2006]. For each of 20 coincidences identified within plus or minus 1 degree latitude, plus or minus 2 degrees longitude and less than 1 hour time the frost point temperatures were calculated using the corresponding SABER temperature profile and water vapor densities of 1,3, and 10 ppmv. We found that the PMC presence and brightness correlated only with the temperature threshold that corresponds to the frost point. The absolute value of the temperature below the frost point, however, didn't play a significant role in the intensity of PMC signal for the majority of selected coincidences. The presence of several bright clouds at temperatures above the frost point is obviously related to the limitation of the limb geometry when some near- or far-field PMCs located at higher (and warmer) altitudes appear to be at lower altitudes.

  10. Seasonal and interannual variations of mesospheric gravity waves and background winds

    NASA Astrophysics Data System (ADS)

    Hoffmann, P.; Rapp, M.; Becker, E.; Placke, M.

    2011-12-01

    The seasonal variation of the activity of gravity waves (GW) in the mesosphere/lower thermosphere is investigated using wind measurements with meteor and MF radars at Juliusruh (55°N, 13°E) and Andenes (69°N, 16°E), as well as on the basis of the simulated annual cycle using a gravity-wave resolving mechanistic general circulation model. Observational and computational results show the strongest GW energy during winter and a secondary maximum during summer. Additional observational analysis of short-period GWs yields a more pronounced summer maximum. The semi-annual variation is consistent with the selective filtering of westward and eastward GWs by the mean zonal wind. The latitudinal dependence during summer is characterized by stronger GW energy between 65 and 85 km at middle latitudes than at polar latitudes, and a corresponding upward shift of the wind reversal towards the pole which is also reflected by the simulated GW drag. Based on long term measurements of mesospheric winds at mid and polar altitudes, the interannual variations of the activity of GW with different periods and their dependence from the background winds are investigated. First results indicate that the observed zonal wind trend at about 75 km during summer at mid latitudes goes along with an enhanced activity of GW with periods between 3 - 6 hours at altitudes between 80 and 88 km. We will continue our studies of GW trends for other seasons at both latitudes to illuminate the contribution of the selective GW filtering by the background winds.

  11. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Transport Through a Precessing Spin Coupled to Noncollinearly Polarized Ferromagnetic Leads

    NASA Astrophysics Data System (ADS)

    Wang, Xian-Chao; Xin, Zi-Hua; Feng, Li-Ya

    2010-02-01

    The quantum electronic transport through a precessing magnetic spin coupled to noncollinearly polarized ferromagnetic leads (F-MS-F) has been studied in this paper. The nonequilibrium Green function approach is used to calculate local density of states (LDOS) and current in the presence of external bias. The characters of LDOS and the electronic current are obtained. The tunneling current is investigated for different precessing angle and different configurations of the magnetization of the leads. The investigation reveals that when the precessing angle takes θ < π/2 and negative bias is applied, the resonant tunneling current appears, otherwise, it appears when positive bias is applied. When the leads are totally polarized and the precessing angel takes 0, the tunneling current changes with the configuration of two leads; and it becomes zero when the two leads are antiparallel.

  12. Evidence for parallel elongated structures in the mesosphere

    NASA Technical Reports Server (NTRS)

    Adams, G. W.; Brosnahan, J. W.; Walden, D. C.

    1983-01-01

    The physical cause of partial reflection from the mesosphere is of interest. Data are presented from an image-forming radar at Brighton, Colorado, that suggest that some of the radar scattering is caused by parallel elongated structures lying almost directly overhead. Possible physical sources for such structures include gravity waves and roll vortices.

  13. Influence of El Nino Southern Oscillation on the Mesospheric Temperature

    NASA Technical Reports Server (NTRS)

    Li, Tao; Calvo, Natalia; Yue, Jia; Dou, Xiankang; Russell, J. M, III; Mlynczak, M. G.; She, Chiao-Yao; Xue, Xianghui

    2013-01-01

    Using the middle atmosphere temperature data set observed by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) satellite experiment between 2002 and 2012, and temperatures simulated by the Whole Atmospheric Community Climate Model version 3.5 (WACCM3.5) between 1953 and 2005, we studied the influence of El Niño-Southern Oscillation (ENSO) on middle atmosphere temperature during the Northern Hemisphere (NH) wintertime. For the first time, a significant winter temperature response to ENSO in the middle mesosphere has been observed, with an anomalous warming of approximately 1.0 K/MEI (Multivariate ENSO Index) in the tropics and an anomalous cooling of approximately 2.0 K/MEI in the NH middle latitudes. The observed temperature responses to ENSO in the mesosphere are opposite to those in the stratosphere, in agreement with previous modeling studies. Temperature responses to ENSO observed by SABER show similar patterns to those simulated by the WACCM3.5 model. Analysis of the WACCM3.5 residual mean meridional circulation response to ENSO reveals a significant downwelling in the tropical mesosphere and upwelling in the NH middle and high latitudes during warm ENSO events, which is mostly driven by anomalous eastward gravity wave forcing in the NH mesosphere.

  14. Influence of El Nino Southern Oscillation on the Mesospheric Temperature

    NASA Technical Reports Server (NTRS)

    Li, Tao; Calvo, Natalia; Yue, Jia; Dou, Xiankang; Russell, J. M, III; Mlynczak, M. G.; She, Chiao-Yao; Xue, Xianghui

    2013-01-01

    Using the middle atmosphere temperature data set observed by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) satellite experiment between 2002 and 2012, and temperatures simulated by the Whole Atmospheric Community Climate Model version 3.5 (WACCM3.5) between 1953 and 2005, we studied the influence of El Niño-Southern Oscillation (ENSO) on middle atmosphere temperature during the Northern Hemisphere (NH) wintertime. For the first time, a significant winter temperature response to ENSO in the middle mesosphere has been observed, with an anomalous warming of approximately 1.0 K/MEI (Multivariate ENSO Index) in the tropics and an anomalous cooling of approximately 2.0 K/MEI in the NH middle latitudes. The observed temperature responses to ENSO in the mesosphere are opposite to those in the stratosphere, in agreement with previous modeling studies. Temperature responses to ENSO observed by SABER show similar patterns to those simulated by the WACCM3.5 model. Analysis of the WACCM3.5 residual mean meridional circulation response to ENSO reveals a significant downwelling in the tropical mesosphere and upwelling in the NH middle and high latitudes during warm ENSO events, which is mostly driven by anomalous eastward gravity wave forcing in the NH mesosphere.

  15. Spatial Heterodyne Imager for Mesospheric Radicals on STPSat-1

    DTIC Science & Technology

    2010-10-22

    by many other sat- ellite experiments such as MLS, OSIRIS, or the suite of instruments on the NASA Aeronomy of Ice in the Meso- sphere (AIM... Aeronomy of Ice in the Mesosphere (AIM) mission: Overview and early science results, J. Atmos. Sol. Terr. Phys., 71, 289–299. Sander, S. P., et al

  16. Estimating pesticide sampling rates by the polar organic chemical integrative sampler (POCIS) in the presence of natural organic matter and varying hydrodynamic conditions

    USGS Publications Warehouse

    Charlestra, Lucner; Amirbahman, Aria; Courtemanch, David L.; Alvarez, David A.; Patterson, Howard

    2012-01-01

    The polar organic chemical integrative sampler (POCIS) was calibrated to monitor pesticides in water under controlled laboratory conditions. The effect of natural organic matter (NOM) on the sampling rates (Rs) was evaluated in microcosms containing -1 of total organic carbon (TOC). The effect of hydrodynamics was studied by comparing Rs values measured in stirred (SBE) and quiescent (QBE) batch experiments and a flow-through system (FTS). The level of NOM in the water used in these experiments had no effect on the magnitude of the pesticide sampling rates (p > 0.05). However, flow velocity and turbulence significantly increased the sampling rates of the pesticides in the FTS and SBE compared to the QBE (p < 0.001). The calibration data generated can be used to derive pesticide concentrations in water from POCIS deployed in stagnant and turbulent environmental systems without correction for NOM.

  17. Mesospheric Mountain Wave Breaking and Oceanic Wave Signatures During DEEPWAVE

    NASA Astrophysics Data System (ADS)

    Taylor, M. J.; Pautet, P. D.; Fritts, D. C.; Doyle, J. D.; Eckermann, S. D.; Williams, B. P.; Kaifler, B.; Bossert, K.; Criddle, N.

    2015-12-01

    DEEPWAVE is an international program designed to quantify gravity wave (GW) dynamics and effects from the ground to the upper mesosphere in unprecedented detail utilizing a range of airborne and ground-based measurements. DEEPWAVE was based on the South Island, New Zealand, to provide access to well-documented, but little understood, New Zealand and Tasmania "hotspots" as identified in satellite stratospheric measurements. Deep orographic GWs over New Zealand were a primary target, but multiple flights were also conducted over the Southern Ocean and Tasman Sea to quantify deep GW arising from convection, jet streams, and frontal systems. This presentation highlights new airborne and ground-based results obtained using an Advanced OH Mesospheric Temperature Mapper (AMTM) which creates high-quality intensity and temperature maps of a broad spectrum of mesospheric GWs. Two AMTM's were employed, one sited at the NIWA Observatory, Lauder (45°S), on the South Island, and one on the NSF GV Gulfstream aircraft which was supplemented by two side viewing IR OH imagers providing large field, ~900 km cross-track, GW maps. These instruments formed part of a comprehensive measurements capability including airborne Rayleigh and Na lidars, dropsondes, ground-based Rayleigh lidar, all-sky imagers and wind measurements. A total of 25 long duration (typically 7-8 hours) nighttime flights were conducted creating an exceptionally rich data set. Here we focus on two key initial findings (a) discovery of large amplitude, mesospheric mountain waves and their intermittent wave breaking signatures, and (b) first measurements of large-field open-ocean mesospheric GW and their near-identical stratospheric wave signatures using AIRS satellite and model forecasting data.

  18. Choosing the polarity of the phase-encoding direction in diffusion MRI: Does it matter for group analysis?

    PubMed Central

    Kennis, M.; van Rooij, S.J.H.; Kahn, R.S.; Geuze, E.; Leemans, A.

    2016-01-01

    Notorious for degrading diffusion MRI data quality are so-called susceptibility-induced off-resonance fields, which cause non-linear geometric image deformations. While acquiring additional data to correct for these distortions alleviates the adverse effects of this artifact drastically – e.g., by reversing the polarity of the phase-encoding (PE) direction – this strategy is often not an option due to scan time constraints. Especially in a clinical context, where patient comfort and safety are of paramount importance, acquisition specifications are preferred that minimize scan time, typically resulting in data obtained with only one PE direction. In this work, we investigated whether choosing a different polarity of the PE direction would affect the outcome of a specific clinical research study. To address this methodological question, fractional anisotropy (FA) estimates of FreeSurfer brain regions were obtained in civilian and combat controls, remitted posttraumatic stress disorder (PTSD) patients, and persistent PTSD patients before and after trauma-focused therapy and were compared between diffusion MRI data sets acquired with different polarities of the PE direction (posterior-to-anterior, PA and anterior-to-posterior, AP). Our results demonstrate that regional FA estimates differ on average in the order of 5% between AP and PA PE data. In addition, when comparing FA estimates between different subject groups for specific cingulum subdivisions, the conclusions for AP and PA PE data were not in agreement. These findings increase our understanding of how one of the most pronounced data artifacts in diffusion MRI can impact group analyses and should encourage users to be more cautious when interpreting and reporting study outcomes derived from data acquired along a single PE direction. PMID:27158586

  19. Choosing the polarity of the phase-encoding direction in diffusion MRI: Does it matter for group analysis?

    PubMed

    Kennis, M; van Rooij, S J H; Kahn, R S; Geuze, E; Leemans, A

    2016-01-01

    Notorious for degrading diffusion MRI data quality are so-called susceptibility-induced off-resonance fields, which cause non-linear geometric image deformations. While acquiring additional data to correct for these distortions alleviates the adverse effects of this artifact drastically - e.g., by reversing the polarity of the phase-encoding (PE) direction - this strategy is often not an option due to scan time constraints. Especially in a clinical context, where patient comfort and safety are of paramount importance, acquisition specifications are preferred that minimize scan time, typically resulting in data obtained with only one PE direction. In this work, we investigated whether choosing a different polarity of the PE direction would affect the outcome of a specific clinical research study. To address this methodological question, fractional anisotropy (FA) estimates of FreeSurfer brain regions were obtained in civilian and combat controls, remitted posttraumatic stress disorder (PTSD) patients, and persistent PTSD patients before and after trauma-focused therapy and were compared between diffusion MRI data sets acquired with different polarities of the PE direction (posterior-to-anterior, PA and anterior-to-posterior, AP). Our results demonstrate that regional FA estimates differ on average in the order of 5% between AP and PA PE data. In addition, when comparing FA estimates between different subject groups for specific cingulum subdivisions, the conclusions for AP and PA PE data were not in agreement. These findings increase our understanding of how one of the most pronounced data artifacts in diffusion MRI can impact group analyses and should encourage users to be more cautious when interpreting and reporting study outcomes derived from data acquired along a single PE direction.

  20. Subseasonal variability of water vapor in the upper stratosphere/lower mesosphere over Northern Europe in winter 2009/2010

    NASA Astrophysics Data System (ADS)

    Peters, D. H. W.; Hallgren, K.; Lübken, F.-J.; Hartogh, P.

    2014-07-01

    For the upper stratosphere and lower mesosphere (USLM) we used microwave spectrometer measurements of water vapor to investigate the cause of subseasonal variability over Northern Europe: at ALOMAR (Andenes, 69.3° N, 16.1° E), Northern Norway, and at the Leibniz Institute of Atmospheric Physics (Kühlungsborn, 54.2° N, 11.8° E), Northern Germany, for winter 2009/2010. The MERRA data set of NASA is applied to study the dynamical link between the local variability of H2O and transport in the USLM. Besides a slow increase in January and a stronger decrease in February and March 2010, episodes of significant increase and decrease of H2O were found over Northern Germany. These structural changes are in good agreement with MERRA which show similar patterns induced by a dominant conservative horizontal transport of H2O. Due to the strong negative meridional gradient and mixing barrier, higher values of water vapor have been observed outside the polar vortex and lower values inside. We found that the complex polar vortex evolution over Northern Germany during the minor stratospheric sudden warming (mSSW) in the beginning of December 2009 and the major warming (MSSW) at the end of January 2010, as well as between the two, fits well into this relationship. An episode of strong increase in water vapor over ALOMAR at about 55-60 km altitude was observed during the MSSW on the 27th of January 2010 resulting in a significant double peak in altitude. Based on MERRA data we show that this dual peak was caused by a relatively strong regional northward propagation of more moist air in the lower mesosphere. In the lower mesosphere strong polar intrusion of warm and moist air occurred mainly over Northern Europe resulting in a well-mixed polar anticyclone on the 30th of January. In comparison with observations the local maxima of H2O in MERRA are underestimated by approximately 1-2 ppmv. After the MSSW, the vertical descent rate of the MERRA reanalysis is half as much as the

  1. The Detached Haze Layer in Titan's Mesosphere

    NASA Astrophysics Data System (ADS)

    Lavvas, P.; Yelle, R. V.; Vuitton, V.

    2008-12-01

    The Cassini observations reveal the presence of a detached haze layer in Titan's mesosphere at an altitude of 520 km, well above the stratosphere. Observations of scattered light made by the Imaging Science Subsystem (ISS) reveal a clearly defined layer encircling low and mid-latitude regions. The aerosol layer is also detected in stellar occultation measurements of UV extinction by the UltraViolet Imaging Spectrometer (UVIS). The haze is a global and permanent feature of Titan's atmosphere. Furthermore the location of the detached haze layer is coincident with and the likely cause of a local maximum in the temperature profile measured by the Huygens Atmospheric Structure Instrument (HASI). This temperature inversion is also permanent and global, having been detected in ground-based stellar occultations. The correlation between the extinction profile and the temperature maximum imply that the detached haze cannot be due to condensation, as previously suggested. Previously, Voyager high phase angle images at 500 nm revealed a detached haze layer near 350 km, more than 150 km lower than the Cassini layer. Close examination of the Voyager images suggests that the Cassini detached layer at 520 km is a separate phenomenon rather than a change in the Voyager detached layer. Analysis of the observed optical properties suggests that the average size of particles in the Cassini detached layer is < 45 nm, with an imaginary index k < 0.3 at 187.5 nm, while Non-LTE calculations of the temperature perturbation induced by the detached haze show that the average particle size must be greater than 35 nm for reproducing the heating rate implied by the HASI temperature profile. Calculation of the sedimentation velocity of the particles, coupled with the derived number density, imply a mass flux of 1.9-3.2 × 10-14 g cm-2 s-1. This is approximately equal to the mass flux required to explain the main haze layer and suggests that the stratospheric haze is formed primarily by

  2. SWAS observations of water vapor in the Venus mesosphere

    NASA Astrophysics Data System (ADS)

    Gurwell, Mark A.; Melnick, Gary J.; Tolls, Volker; Bergin, Edwin A.; Patten, Brian M.

    2007-06-01

    We present the first detections of the ground-state H 216O ( 1-1) rotational transition (at 556.9 GHz) and the 13CO (5-4) rotational transition from the atmosphere of Venus, measured with the Submillimeter Wave Astronomy Satellite (SWAS). The observed spectral features of these submillimeter transitions originate primarily from the 70-100 km altitude range, within the Venus mesosphere. Observations were obtained in December 2002, and January, March, and July 2004, coarsely sampling one Venus diurnal period as seen from Earth. The measured water vapor absorption line depth shows large variability among the four observing periods, with strong detections of the line in December 2002 and July 2004, and no detections in January and March 2004. Retrieval of atmospheric parameters was performed using a multi-transition inversion algorithm, combining simultaneous retrievals of temperature, carbon monoxide, and water profiles under imposed constraints. Analysis of the SWAS spectra resulted in measurements or upper limits for the globally averaged mesospheric water vapor abundance for each of the four observation periods, finding variability over at least two orders of magnitude. The results are consistent with both temporal and diurnal variability, but with short-term fluctuations clearly dominating. These results are fully consistent with the long-term study of mesospheric water vapor from millimeter and submillimeter observations of HDO [Sandor, B.J., Clancy, R.T., 2005. Icarus 177, 129-143]. The December 2002 observations detected very rapid change in the mesospheric water abundance. Over five days, a deep water absorption feature consistent with a water vapor abundance of 4.5±1.5 parts per million suddenly gave way to a significantly shallower absorption, implying a decrease in the water vapor abundance by a factor of nearly 50 in less that 48 h. In 2004, similar changes in the water vapor abundance were measured between the March and July SWAS observing periods, but

  3. The Sensitivity of Venus' Oxygen Budget to Venus' Mesospheric Temperature

    NASA Astrophysics Data System (ADS)

    Jessup, K.; Mills, F.; Yung, Y.; Allen, M.

    2009-05-01

    The dominant chemical cycle in Venus' mesosphere above the clouds (70-110 km altitude) is the CO2 cycle. The primary steps of this cycle are photodissociation of CO2 to produce CO and O on the day side, transport of CO and O from the day side to the night side, formation of O2 on the day and night sides, and production of CO2 from CO and O2. Many photochemical models have attempted to identify the mechanisms by which CO2 is produced, but none has satisfactorily reproduced the observational upper limit on the O2 abundance (Trauger and Lunine 1983, Krasnopolsky 2006). In these models (Yung and DeMore 1982, Krasnopolsky and Parshev 1983, Pernice et al 2004) the assumed mesospheric vertical pressure and temperature profiles were derived from Pioneer Venus data. However, recent SPICAV observations (Bertaux et al. 2007) indicate mesospheric temperatures at 110 km may be up to 50 K warmer than the standard values adopted from the Pioneer Venus data. The CO2 cross section is sensitive to temperature, so an increase in temperature in the upper part of the mesosphere will increase photodissociation in the upper part of the mesosphere and decrease photodissociation at lower altitudes. These changes should, in turn, affect the abundances and vertical profiles of CO, O2 and O. We have developed a simplified version of the Caltech/JPL photochemical model (Allen et al. 1981) which limits the mesospheric chemistry solely to carbon and oxygen species. Using temperature dependent CO2 cross-section data in this model, we will investigate the impact of temperature on the vertical profile of CO2 photodissociation and the calculated abundances of CO, O, and O2. Two sets of temperature dependent CO2 cross section data a) Lewis and Carver 1983, and b) Yoshino et al. 1996; Parkinson et al 2003 will be utilized in this study. The sensitivity of the model results to differences between the two sets of cross section measurements will be quantified.

  4. Interaction of polar and nonpolar organic pollutants with soil organic matter: sorption experiments and molecular dynamics simulation.

    PubMed

    Ahmed, Ashour A; Thiele-Bruhn, Sören; Aziz, Saadullah G; Hilal, Rifaat H; Elroby, Shaaban A; Al-Youbi, Abdulrahman O; Leinweber, Peter; Kühn, Oliver

    2015-03-01

    The fate of organic pollutants in the environment is influenced by several factors including the type and strength of their interactions with soil components especially SOM. However, a molecular level answer to the question "How organic pollutants interact with SOM?" is still lacking. In order to explore mechanisms of this interaction, we have developed a new SOM model and carried out molecular dynamics (MD) simulations in parallel with sorption experiments. The new SOM model comprises free SOM functional groups (carboxylic acid and naphthalene) as well as SOM cavities (with two different sizes), simulating the soil voids, containing the same SOM functional groups. To examine the effect of the hydrophobicity on the interaction, the organic pollutants hexachlorobenzene (HCB, non-polar) and sulfanilamide (SAA, polar) were considered. The experimental and theoretical investigations explored four major points regarding sorption of SAA and HCB on soil, yielding the following results. 1--The interaction depends on the SOM chemical composition more than the SOM content. 2--The interaction causes a site-specific adsorption on the soil surfaces. 3--Sorption hysteresis occurs, which can be explained by inclusion of these pollutants inside soil voids. 4--The hydrophobic HCB is adsorbed on soil stronger than the hydrophilic SAA. Moreover, the theoretical results showed that HCB forms stable complexes with all SOM models in the aqueous solution, while most of SAA-SOM complexes are accompanied by dissociation into SAA and the free SOM models. The SOM-cavity modeling had a significant effect on binding of organic pollutants to SOM. Both HCB and SAA bind to the SOM models in the order of models with a small cavity>a large cavity>no cavity. Although HCB binds to all SOM models stronger than SAA, the latter is more affected by the presence of the cavity. Finally, HCB and SAA bind to the hydrophobic functional group (naphthalene) stronger than to the hydrophilic one (carboxylic acid

  5. Frequency spectra and vertical profiles of wind fluctuations in the summer Antarctic mesosphere revealed by MST radar observations

    NASA Astrophysics Data System (ADS)

    Sato, Kaoru; Kohma, Masashi; Tsutsumi, Masaki; Sato, Toru

    2017-01-01

    Continuous observations of polar mesosphere summer echoes at heights from 81-93 km were performed using the first Mesosphere-Stratosphere-Troposphere/Incoherent Scatter radar in the Antarctic over the three summer periods of 2013/2014, 2014/2015, and 2015/2016. Power spectra of horizontal and vertical wind fluctuations, and momentum flux spectra in a wide-frequency range from (8 min)-1 to (20 days) -1 were first estimated for the Antarctic summer mesosphere. The horizontal (vertical) wind power spectra obey a power law with an exponent of approximately -2 (-1) at frequencies higher than the inertial frequency of (13 h)-1 and have isolated peaks at about 1 day and a half day. In addition, an isolated peak of a quasi-2 day period is observed in the horizontal wind spectra but is absent from the vertical wind spectra, which is consistent with the characteristics of a normal-mode Rossby-gravity wave. Zonal (meridional) momentum flux spectra are mainly positive (negative), and large fluxes are observed in a relatively low-frequency range from (1 day)-1 to (1 h)-1. A case study was performed to investigate vertical profiles of momentum fluxes associated with gravity waves and time mean winds on and around 3 January 2015 when a minor stratospheric warming occurred in the Northern Hemisphere. A significant momentum flux convergence corresponding to an eastward acceleration of 200 m s-1 d-1 was observed before the warming and became stronger after the warming when mean zonal wind weakened. The strong wave forcing roughly accorded with the Coriolis force of mean meridional winds.

  6. The crystal structure of ice under mesospheric conditions

    NASA Astrophysics Data System (ADS)

    Murray, Benjamin J.; Malkin, Tamsin L.; Salzmann, Christoph G.

    2015-05-01

    Ice clouds form in the summer high latitude mesopause region, which is the coldest part of the Earth's atmosphere. At these very low temperatures (<150 K) ice can exist in metastable forms, but the nature of these ices remains poorly understood. In this paper we show that ice which is grown at mesospherically relevant temperatures does not have a structure corresponding to the well-known hexagonal form or the metastable cubic form. Instead, the ice which forms under mesospheric conditions is a material in which cubic and hexagonal sequences of ice are randomly arranged to produce stacking disordered ice (ice Isd). The structure of this ice is in the trigonal crystal system, rather than the cubic or hexagonal systems, and is expected to produce crystals with aspect ratios consistent with lidar observations.

  7. The accuracy of Nimbus 7 LIMS temperatures in the mesosphere

    NASA Astrophysics Data System (ADS)

    Remsberg, E. E.

    1986-04-01

    Zonal-mean temperatures from the Nimbus 7 Limb Infrared Monitor of the Stratosphere (LIMS) experiment are compared with a temperature 'climatology' derived from 4 years of Rayleigh backscatter lidar measurements at 44 N and for the months of March, April, and May, when wave activity and thus atmospheric variability is very weak. The mean difference between the two data sets is less than 3.5 K between 37 and 64 km and is consistent with the theoretical estimates of accuracy reported for the LIMS data. The effects of longitudinal and year-to-year variaiations in this comparison were considered, but they do not change the conclusions significantly. These validation results extend the altitude range of accurate LIMS temperatures in the mesosphere some 10 km higher than previously reported. It also means the LIMS ozone and NO2 retrievals in the lower mesosphere should be free of any major temperature bias error effects.

  8. Report of the Ionosphere-Thermosphere-Mesosphere Panel

    NASA Technical Reports Server (NTRS)

    Szuszczewicz, Edward P.; Killeen, Tim L.; Arnoldy, Roger L.; Brace, Larry H.; Christensen, Andrew B.; Fejer, B.; Heelis, Roderick A.; Keskinen, Michael J.; Maynard, Nelson C.; Mayr, Hans G.

    1991-01-01

    The scientific objectives and mission concept that emerged from the discussions of this panel are presented. The overall scientific theme of this report is the investigation of the ionosphere, thermosphere, and mesosphere (near Earth space environment) as a global, dynamic, and coupled system. Among the specific goals of this area of research are: (1) understanding the consequences of transition between turbulent and laminar flow and collisional and collisionless media; (2) understanding the thermospheric/mesospheric coupling due to gravity wave, tidal, and trace constituent transport processes; (3) understanding the electrodynamical coupling between the thermosphere/ionosphere and magnetosphere; (4) understanding the coupling processes between small scale plasma structures; and (5) determining the real-time evolution of the global ionosphere electric field in response to solar wind and magnetosphere coupling.

  9. Summary of Sessions: Ionosphere - Thermosphere - Mesosphere Working Group

    NASA Technical Reports Server (NTRS)

    Spann, J. F.; Bhattacharyya, A.

    2006-01-01

    The topics covered by the sessions under the working group on Ionosphere-Thermosphere-Mesosphere dealt with various aspects of the response of the ionosphere-thermosphere coupled system and the middle atmosphere to solar variability. There were four plenary talks related to the theme of this working group, thirteen oral presentations in three sessions and six poster presentations. A number of issues related to effects of solar variability on the ionosphere-thermosphere, observed using satellite and ground-based data including ground magnetometer observations, radio beacon studies of equatorial spread F, and modeling of some of these effects, were discussed. Radar observations of the mesosphere-lower thermosphere region and a future mission to study the coupling of thunderstorm processes to this region, the ionosphere, and magnetosphere were also presented.

  10. Equatorial Enhancement of the Nighttime OH Mesospheric Infrared Airglow

    NASA Technical Reports Server (NTRS)

    Baker, D. J.; Mlynczak, M. G.; Russell, J. M.

    2007-01-01

    Global measurements of the hydroxyl mesospheric airglow over an extended period of time have been made possible by the NASA SABER infrared sensor aboard the TIMED satellite which has been functioning since December of 2001. The orbital mission has continued over a significant portion of a solar cycle. Experimental data from SABER for several years have exhibited equatorial enhancements of the nighttime mesospheric OH (delta v = 2) airglow layer consistent with the high average diurnal solar flux. The brightening of the OH airglow typically means more H + O3 is being reacted. At both the spring and autumn seasonal equinoxes when the equatorial solar UV irradiance mean is greatest, the peak volume emission rate (VER) of the nighttime Meinel infrared airglow typically appears to be both significantly brighter plus lower in altitude by several kilometres at low latitudes compared with midlatitude findings.

  11. Seasonal Characteristics of Mesospheric Plasma and Their Transitions

    NASA Technical Reports Server (NTRS)

    Lauter, E. A.

    1984-01-01

    The main seasonal features of the middle atmosphere are arising from the different dynamical basic states in winter and summer. The development of the two controversial circulation systems and the also different peculiarities of transition between them in spring and autumn create the completely dominant seasonal variations in strato- and mesosphere. Even in the plasma structures of the mesospheric D-region the seasonal variation is towering above the amplitudes of extraterrestrial influences. From standard ionospheric sounding, significant seasonal D- and E-region effects, adhering to equally significant structure changes in the neutral gas in the height region from 20 to 100 km were discovered. Results about such typical seasonal features are summarized.

  12. Report of the Ionosphere-Thermosphere-Mesosphere Panel

    NASA Technical Reports Server (NTRS)

    Szuszczewicz, Edward P.; Killeen, Tim L.; Arnoldy, Roger L.; Brace, Larry H.; Christensen, Andrew B.; Fejer, B.; Heelis, Roderick A.; Keskinen, Michael J.; Maynard, Nelson C.; Mayr, Hans G.

    1991-01-01

    The scientific objectives and mission concept that emerged from the discussions of this panel are presented. The overall scientific theme of this report is the investigation of the ionosphere, thermosphere, and mesosphere (near Earth space environment) as a global, dynamic, and coupled system. Among the specific goals of this area of research are: (1) understanding the consequences of transition between turbulent and laminar flow and collisional and collisionless media; (2) understanding the thermospheric/mesospheric coupling due to gravity wave, tidal, and trace constituent transport processes; (3) understanding the electrodynamical coupling between the thermosphere/ionosphere and magnetosphere; (4) understanding the coupling processes between small scale plasma structures; and (5) determining the real-time evolution of the global ionosphere electric field in response to solar wind and magnetosphere coupling.

  13. Spherical solitons in Earth’S mesosphere plasma

    SciTech Connect

    Annou, K.; Annou, R.

    2016-01-15

    Soliton formation in Earth’s mesosphere plasma is described. Nonlinear acoustic waves in plasmas with two-temperature ions and a variable dust charge where transverse perturbation is dealt with are studied in bounded spherical geometry. Using the perturbation method, a spherical Kadomtsev–Petviashvili equation that describes dust acoustic waves is derived. It is found that the parameters taken into account have significant effects on the properties of nonlinear waves in spherical geometry.

  14. Thermosphere-Ionosphere-Mesosphere Modeling Using the TIME-GCM

    DTIC Science & Technology

    2014-09-30

    Systems Modeling effort in examining the couplings between the upper and lower atmospheres and in an attempt to understand the effects of the variable...Thermosphere-Ionosphere-Mesosphere Modeling Using the TIME-GCM Raymond G. Roble High Altitude Observatory National Center for Atmospheric ...http://www.hao.ucar.edu/ LONG-TERM GOALS A major goal of the research is to understand how elements in the coupled upper atmosphere

  15. Mesospheric optical signatures of possible lightning on Venus

    NASA Astrophysics Data System (ADS)

    Pérez-Invernón, F. J.; Luque, A.; Gordillo-Vázquez, F. J.

    2016-07-01

    A self-consistent two-dimensional model is proposed to account for the transient mesospheric nighttime optical emissions associated to possible intracloud (IC) lightning occurring in the Venusian troposphere. The model calculates the mesospheric (between 75 km and 120 km in altitude) quasi-elestrostatic electric field and electron density produced in response to IC lightning activity located between 40 km and 65 km in the Venusian cloud layer. The optical signatures and the densities of perturbed excited atomic and molecular neutral and ionic species in the mesosphere of Venus are also calculated using a basic kinetic scheme. The calculations were performed for different IC lightning discharge properties. We found that the calculated electric fields in the mesosphere of Venus are above breakdown values and that, consequently, visible transient glows (similar to terrestrial Halos produced by lightning) right above the parent IC lightning are predicted. The transient optical emissions result from radiative deexcitation of excited electronic states of N2 (in the ultraviolet, visible and near-infrared ranges) and of O(1S) and of O(1D) in, respectively, the green (557 nm) and red (630 nm) wavelengths. The predicted transient lightning-induced glows from O(1S) can reach an intensity higher than 167 R and, consequently, be above the detection threshold of the Lightning and Airglow Camera instrument aboard the Japanese Akatsuki probe orbiting Venus since December 2015. However, according to our model, successful observations of transient lightning-induced optical glows could only be possible for sufficiently close (300 km or maximum 1000 km) distances.

  16. New numerical model of mesospheric bores: Observational implications

    NASA Astrophysics Data System (ADS)

    Picard, R. H.; Cohen, E.; Dewan, E. M.; Winick, J. R.; Taylor, M. J.; She, C.-Y.

    Mesospheric bores are space-time varying frontal structures that may play a role in transport and coupling between horizontally separated regions. We examine the observational implications of a new numerical model of the generation and propagation of mesospheric bores. The bores develop as long-wave excitations in mesospheric wave ducts, formed by the temperature and wind structure, in much the same way as they do in the tropospheric boundary-layer duct. However, while the boundary-layer duct has a clamped ground boundary (zero vertical displacement), the embedded mesospheric duct has two free boundaries, which results in some differences in behavior. With a separability assumption valid in the long-wave limit, the fluid equations separate into a product of solutions of the Taylor-Goldstein equation describing the vertical dependence of the mode function and of the Benjamin-Davis-Ono (BDO) equation describing the horizontal and time behavior. We compare results of the numerical model with the analytic model of Dewan and Picard (1998) that is based on Lighthill's channel-bore solutions. The numerical model leads to predictions of new or as-yet-unobserved phenomena, including (1) the conceivable existence of bores in Doppler ducts, (2) the existence of a fast sinuous-mode bore with no channel-bore analogue having phase speeds of 150-180 m/s, and (3) the possibility of foaming or turbulent (non-undular) bores. Following Christie (1989), we model the turbulent dissipation processes in the latter case by including a Burgers-type term in the BDO equation. We also discuss the response of emitted radiance to bores and compare model predictions with recent bore observations accompanied by simultaneous lidar data [Smith et al., 2001; She et al., 2004].

  17. Ozone and Wind Variations in the Stratosphere and Mesosphere.

    DTIC Science & Technology

    1978-12-31

    75 km NTIS GF"I DWC TAB R. J. Lucas Unannounced _4 Justification Department of Physics and Astronomy, By University College London, Distribuy...for the Umkehr results these were ± one standard deviation divided by the root of the nimber of observations (the standard error of the mean). This...diurnal multiplication factors for the mesospheric ozone model. Column I gives the time in twentieths of the interval between sunrise and sunset. 7g

  18. First UV Satellite Observations of Mesospheric Water Vapor

    DTIC Science & Technology

    2008-06-21

    Rottman et al., 1993] on UARS, which has an absolute accuracy of about 3.5% near 280 nm [ Woods et al., 1996]. We degrade the Kohl et al. [1978... near 280 nm [ Woods et al., 1996] and 3% for the wavelength uncertainty of the solar atlas [Kohl et al., 1978]. The total root-sum-squared 1-s...Finally, previous satellite observations of mesospheric water vapor have been made at infrared and microwave wavelengths. There have been no UV

  19. Inter-seasonal observations of Mesospheric Hydroxyl by SHIMMER (Invited)

    NASA Astrophysics Data System (ADS)

    Englert, C. R.; Stevens, M. H.; Siskind, D. E.; Harlander, J.; Roesler, F. L.

    2009-12-01

    The Spatial Heterodyne Imager for Mesospheric Radicals (SHIMMER) on STPSat-1 is a high resolution, UV, mesospheric, limb sounder that uses the innovative optical technique of Spatial Heterodyne Spectroscopy (SHS). For extended sources, SHS facilitates significant size and weight savings when compared to conventional grating spectrographs with similar spectral resolution and sensitivity. SHIMMER images the limb near 309nm with a spectral resolution of ~250mÅ, which allows for the observation of the OH A2Σ+--X2Π(0,0) band. From these observations we retrieve OH density profiles from 90 to 60 km altitude. SHIMMER data covers more than 2.5 years starting in April 2007. The low inclination orbit and seasonal yaw cycle allow SHIMMER to measure up to about 58° latitude in the summer hemisphere and up to about 12° in the winter hemisphere. The orbit precesses approximately 30 minutes per day, allowing the investigation of diurnal variations. In this presentation we compare SHIMMER OH profiles with coincident Microwave Limb Sounder (MLS) data from the Aura mission and photochemical model calculations for different latitudes and seasons. We will also compare the SHIMMER OH results with measurements taken by the Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI) in 1997. In particular, we will revisit the previously reported mesospheric OH model excess and what impact the new SHIMMER data-set has on this problem.

  20. Morphology and sources of turbulence in the mesosphere during DYANA

    NASA Astrophysics Data System (ADS)

    Lubken, F.-J.; Hillert, W.; Lehmacher, G.; von Zahn, U.; Blix, T. A.; Thrane, E. V.; Widdel, H.-U.; Kokin, G. A.; Knyazev, A. K.

    1994-12-01

    During the DYnamics Adapted Network for the Atmosphere (DYANA) campaign in early 1990 turbulent parameters were measured at various places by means of in situ and ground supported techniques. Rocket borne instruments detected small-scale fluctuations of neutral (TOTAL instrument) and ion (PIP instrument) number densities in the mesosphere and lower thermosphere. A total of six flights was successfully performed in Andoya (69 deg N) and two in Biscarosse (44 deg N). Altitude profiles of turbulent parameters, such as turbulent energy dissipation rates epsilon and turbulent diffusion coefficients Kappa were derived from the fluctuations. Thanks to improvements in the instrumental capabilities, the reliability of the absolute values is unprecedented. The mean turbulent energy dissipation rates measured both by TOTAL and PIP in Andoya show very low values (less than 1 mW/kg) in the lower mesosphere, increasing to approximately 10 W/kg in the upper mesosphere. The corresponding heating rates are approximately 0.05 and 1 K/day, respectively. The two flights performed in Biscarosse showed similar low values. In addition to the in situ measurements, energy dissipation rates were measured around 75 km by the chaff dispersion technique at Heiss Island (81 deg N) and at Volgograd (48 deg N). Much higher epsilon values were observed (typically 100 mW/kg) using this procedure than those values obtained by in situ measurements.

  1. Simulations of a mesospheric source of nitrous oxide in WACCM

    NASA Astrophysics Data System (ADS)

    Kelly, Christopher; Chipperfield, Martyn; Plane, John; Feng, Wuhu; Jackson, David

    2017-04-01

    The UK Met Office are 'raising the roof' of the Unified Model (UM) from 85 km to 100-140 km. At this increased altitude the impacts of space weather on atmospheric chemistry become more significant. We plan to add a detailed description of the mesosphere/lower thermosphere (MLT) neutral and ion chemistry to this extended UM. The NCAR Whole Atmosphere Community Climate Model (WACCM) has an efficient neutral and ion chemistry scheme that will provide a template for this part of the development. Nitrous oxide (N2O) is the third most significant greenhouse gas associated with climate change. Additionally, when transported down into the stratosphere, N2O has a significant role in the depletion of ozone. It was previously assumed to only be produced at the Earth's surface, however a mesospheric source has since been identified. This was first postulated by Zipf and Prasad (1982), and more recently Sheese et al. (2016) reported satellite observations of large N2O mixing ratios in the upper atmosphere. The likely mechanism for this is energetic electron precipitation (EPP) which promotes N2 to the excited triplet state, followed by a reaction with O2. Currently, WACCM does not include this mesospheric source of N2O. As a first stage in this work we will describe the inclusion of this additional source of N2O in WACCM. We will also compare results from WACCM simulations with and without this additional N2O source.

  2. Mesospheric Winds and Magnetic Fields from the South Pole

    NASA Astrophysics Data System (ADS)

    Martin, C. L.; Burrows, S. M.; Brown, M. J.; Roberts, E. A.

    2007-12-01

    We show how carbon monoxide (CO) can be used as a tracer of mesospheric neutral wind speeds, by measuring small Doppler shifts in its rotational emission spectrum. Since the altitude range we are most sensitive to is generally inaccessible to many other measurement techniques, this fills a significant experimental gap. Using this method, high-resolution ground-based measurements of mesospheric CO taken from the AST/RO sub-millimeter telescope, located at Amundsen-Scott South Pole Station have been used to calculate wind speeds and column densities over the Antarctic from 2002 to 2005. For more information see Burrows et al. JGR-Atmospheres doi:10.1029/2006JD007993. In addition, the 2→ 1 rotational transition of O18O has been measured and used as a tracer of the mesospheric magnetic field over the Antarctic. We demonstrate how the Zeeman splitting of this molecule was used to measure the Earth's magnetic field during the geomagnetic storm of January 2003.

  3. In Situ Sampling of Meteoric Smoke in the Mesosphere

    NASA Astrophysics Data System (ADS)

    Waldemarsson, T.; Giovane, F.; Gumbel, J.; Stroud, R. M.; Hedin, J.; Siskind, D.

    2005-12-01

    The fate of meteoric material in the mesosphere has been a longstanding scientific challenge. Ablated metal compounds undergo complex chemical processes and are thought to ultimately recondense into nanometer-size smoke particles. This meteoric smoke has been suggested as a key player in the mesosphere, but the actual existence of the particles has never been proven. We will present a recently developed instrument, MAGIC (Mesospheric Aerosol - Genesis, Interaction and Composition), designed to sample smoke particles in situ during a rocket flight. The MAGIC instrument has been built at the Naval Research Laboratory with particular emphasis on aerodynamic challenges imposed by the tiny size of the particles. By sampling smoke particles and making them available for laboratory analysis, their existence and properties can be studied. Basic questions concern their number density, size, altitude distribution and composition. The first flight of the MAGIC instrument took place during a rocket campaign at Esrange, Sweden, in January 2005. In May 2005 the second flight took place in collaboration with the Virginia Polytechnic Institute, with launch at Wallops Island, USA. An overview of the campaigns will be presented.

  4. Seasonal variation in equatorial mesospheric temperatures observed by SME

    NASA Astrophysics Data System (ADS)

    Garcia, Rolando R.; Clancy, R. Todd

    1990-07-01

    Observations made by the Solar Mesosphere Explorer (SME) satellite from 1982 through 1986 are used to examine the seasonal variation of temperature in the equatorial mesosphere between 58.5 and 90 km. Near the equator, seasonal variability is dominated by a strong semiannual oscillation (SAO) whose amplitude increases from about 3 K in the lower mesosphere to 7.3 K near 80 km. Above 80 k, the SAO amplitude decreases to a minimum at 83 km, but increases again sharply above that level, reaching 16.6 K at 90 km. The structure of the temperature SAO is consistent with previous observations of the SAOs in temperature and zonal wind, although the very large amplitude at 90 km may be due in part to contamination by the diurnal tide. Just below 80 km, temperatures are warm (cold) near the solstices (equinoxes), implying westerly (easterly) accelerations above; the behavior at 58.5 km lags that at 80 km by about 2 months.

  5. White matter injury and microglia/macrophage polarization are strongly linked with age-related long-term deficits in neurological function after stroke.

    PubMed

    Suenaga, Jun; Hu, Xiaoming; Pu, Hongjian; Shi, Yejie; Hassan, Sulaiman Habib; Xu, Mingyue; Leak, Rehana K; Stetler, R Anne; Gao, Yanqin; Chen, Jun

    2015-10-01

    , aged mice exhibited significantly reduced M2 polarization compared to young adults. Remarkably, we discovered a strong positive correlation between favorable neurological outcomes after dMCAO and MBP levels or the number of M2 microglia/macrophages. In conclusion, our studies suggest that the distal MCAO stroke model consistently results in ischemic brain injury with long-term behavioral deficits, and is therefore suitable for the evaluation of long-term stroke outcomes. Furthermore, aged mice exhibit deterioration of functional outcomes after stroke and this deterioration is linked to white matter damage and reductions in M2 microglia/macrophage polarization.

  6. On the signature of positively charged dust particles on plasma irregularities in the mesosphere

    NASA Astrophysics Data System (ADS)

    Mahmoudian, A.; Scales, W. A.

    2013-11-01

    Recent rocket payloads have studied the properties of aerosol particles within the ambient plasma environment in the polar mesopause region and measured the signature of the positively charged particles with number densities of (2000 cm-3) for particles of 0.5-1 nm in radius. The measurement of significant numbers of positively charged aerosol particles is unexpected from the standard theory of aerosol charging in plasma. Nucleation on the cluster ions is one of the most probable hypotheses for the positive charge on the smallest particles. This work attempts to study the correlation and anti-correlation of fluctuations in the electron and ion densities in the background plasma by adopting the proposed hypothesis of positive dust particle formation. The utility being that it may provide a test for determining the presence of positive dust particles. The results of the model described show good agreement with observed rocket data. As an application, the model is also applied to investigate the electron irregularity behavior during radiowave heating assuming the presence of positive dust particles. It is shown that the positive dust produces important changes in the behavior during Polar Mesospheric Summer Echo PMSE heating experiments that can be described by the fluctuation correlation and anti-correlation properties.

  7. The extraordinarily strong and cold polar vortex in the early northern winter 2015/2016

    NASA Astrophysics Data System (ADS)

    Matthias, V.; Dörnbrack, A.; Stober, G.

    2016-12-01

    The Arctic polar vortex in the early winter 2015/2016 was the strongest and coldest of the last 68 years. Using global reanalysis data, satellite observations, and mesospheric radar wind measurements over northern Scandinavia we investigate the characteristics of the early stage polar vortex and relate them to previous winters. We found a correlation between the planetary wave (PW) activity and the strength and temperature of the northern polar vortex in the stratosphere and mesosphere. In November/December 2015, a reduced PW generation in the troposphere and a stronger PW filtering in the troposphere and stratosphere, caused by stronger zonal winds in midlatitudes, resulted in a stronger polar vortex. This effect was strengthened by the equatorward shift of PWs due to the strong zonal wind in polar latitudes resulting in a southward shift of the Eliassen-Palm flux divergence and hence inducing a decreased deceleration of the polar vortex by PWs.

  8. Impact of horizontal transport, temperature, and PMC uptake on mesospheric Fe at high latitudes

    NASA Astrophysics Data System (ADS)

    Gardner, Chester S.; Huang, Wentao

    2016-06-01

    We analyze year-round Fe lidar observations made in Antarctica at Rothera (67.7°S), South Pole (90°S), and McMurdo (77.8°S). During midsummer, when the mesopause region is continuously sunlit, the Fe density between 84 and 88 km is independent of temperature, because photolysis of FeOH is so fast that virtually all of the FeOH is converted to Fe via this path, rather than via the temperature-dependent FeOH + H reaction. The extremely low summertime densities at Rothera and South Pole are caused primarily by meridional transport northward out of the polar cap and, to a lesser extent, by uptake of Fe species on polar mesospheric cloud (PMC) ice particles. In midwinter, both meridional transport and temperature dominate Fe variations. The temperature sensitivity of Fe during winter is 2.2%/K at Rothera and 3.0%/K at South Pole. The annual mean Fe abundance at McMurdo is more than 50% larger than that observed at any other lidar site in both the Northern and Southern Hemispheres. McMurdo is located at the magnetic poleward edge of the auroral oval, just north of the deep polar cap. We hypothesize that southward transport of Fe+ out of the auroral oval in winter and northward transport of Fe+ out of the deep polar cap and auroral zone in summer, to McMurdo where it is neutralized, could be the source of the enhanced Fe. Theoretical calculations show that Fe+ densities of ~13,000 cm-3 in midwinter and ~1600 cm-3 in midsummer, between 84 and 88 km, are required to account for the high Fe densities at McMurdo.

  9. The investigation of noctilucent clouds and other mesospheric phenomena using ground-based instrumentation and rockets

    NASA Astrophysics Data System (ADS)

    East, Sally Anne

    1993-01-01

    The optical and dynamical properties of the summer phenomena known as Noctilucent Clouds (NLC) have been studied globally since the early 1960s. These clouds only occur naturally in the Earth's mesosphere, and are presently studied using remote sensing from rockets, and satellites in addition to ground-based observations. Direct evidence of the topology, and structure of an aerosol layer, such as a NLC can be achieved using non-imaging photodiode/photometers housed on a rocket payload. The APL designed photometers utilize the spin of the rocket payload, therefore scanning the entire sky laterally, and producing a two- dimensional image of the aerosol layer traversed during the upleg and downleg flights. The APL photodiode/photometers were flown during the MAED (Middle Atmospheric ElectroDynamics) and NLC-91 (NoctiLucent Clouds 1991) summer rocket campaigns respectively. These multinational rocket campaigns were coordinated with ground-based and satellite observations. The resultant APL data provides a complementary data source to be compared and contrasted with other rocket experiments flown during the absence/presence of NLC and/or PMSE (Polar Mesospheric Summer Echoes). A Bomem Michelson Interferometer (MI) was stationed in Sweden during the summer rocket campaign, NLC-91 provided measurements of the hydroxyl (3,1) band emission from a layer positioned ~87 km. The presented data were kindly provided by the Space Dynamics Laboratory, Utah State University; analyzed and interpreted by the author. The data gave a measure of the upper mesospheric conditions during the presence and absence of NLC during the rocket campaign. The interpretation of the raw data gave an indication of stratospheric filtering of upward propagating waves whose diminution could produce the upward forcing that may be involved in the NLC formation processes. Intensity and rotational temperature profiles deduced during the absence/presence of NLC gave clear results of small- and large

  10. Observations of HCl altitude dependence and temporal variation in the 70-100 km mesosphere of Venus

    NASA Astrophysics Data System (ADS)

    Sandor, Brad J.; Clancy, R. Todd

    2012-08-01

    Spectroscopically resolved observations of the 625.9 GHz H35Cl absorption lines were obtained with the James Clerk Maxwell Telescope on October 23, November 7, and December 5, 2010. The nightside atmosphere was observed on all three dates, and the dayside morning crescent was also observed on December 5. Shape of the pressure-broadened absorption constrains altitude distribution of HCl over 70-100 km. Retrieved abundances at 70-80 km are consistent with 74 km values reported by Krasnopolsky (Krasnopolsky, V.A. [2010]. Icarus 208, 539-547), and do not agree with smaller abundances measured at the North polar terminator with Venus Express (Vandaele, A.C. [2008]. J. Geophys. Res. 113(E00B23), 1-16). Observed HCl mixing ratios decrease rapidly with altitude above 80 km, with 90 km abundances decreased by a factor of two or more relative to those in the lower mesosphere. This behavior is distinctly different from photochemical model profiles, which predict 90 and 110 km mixing ratios only 10% and 25% smaller, respectively, than cloud top values. While model photochemistry indicates HCl should be the dominant chlorine reservoir in the mesosphere and lower thermosphere, observations show HCl abundance is less than half that of total chlorine above 90 km. It directly follows that at least one other chlorine containing molecule must be present in the upper mesosphere at abundances far higher than predicted, which in turn suggests chlorine chemistry in this region differs significantly from the current theoretical understanding. Above 85 km, the equatorial HCl abundances reported here are consistent with polar vortex values from Venus Express, suggesting that the unknown mechanism depleting HCl above 80 km at low latitudes may be important throughout the mesosphere at high latitude. The polar vortex (Venus Express) and equatorial nightside (this study) of Venus are regions of dynamical downwelling, such that downward transport of air from a thermospheric region of HCl

  11. SOIR/VEX mesospheric aerosols observations and modelling

    NASA Astrophysics Data System (ADS)

    Wilquet, Valérie; Carine Vandaele, Ann; Drummond, Rachel; Mahieux, Arnaud; Robert, Séverine; Daerden, Frank; Neary, Lori; Bertaux, Jean-Loup

    2013-04-01

    SPICAV/SOIR on-board Venus Express is able to target the layer of aerosols above the cloud layer at the terminator (Wilquet et al., 2009). A high temporal variability in the aerosol content in Venus' atmosphere was inferred from SOIR observations, as well as a latitudinal dependency of the aerosol loading (Wilquet et al., 2012). This is in agreement with results from previous missions and with the facts that (i) H2SO4 aerosol particles are formed through SO2 photo-oxidation and hydration at the cloud top of Venus, (ii) SO2 photolysis is more efficient at low latitudes, (iii) the altitude of the cloud top is up to one scale height lower in the polar region than at the equator. A increasing SO2 abundance with increasing altitude was recently observed with SPICAV-UV at altitudes of ~ 85-105 km (Belyaev et al., 2012) but also from microwave ground-based spectra in the Venus mesosphere (Sandor et al., 2010), which suggest a source of SO2 at high altitudes. Zhang et al. (2012) proposed a one dimensional photochemistry-diffusion model in order to reconcile these puzzling findings; he suggested that H2SO4 might be a source of SO2 above 90 km through aerosol evaporation followed by SO3 photolysis. This model and the observations are however disputed by others demonstrating the necessity for a more global interpretation of the observations and for modelling of the upper haze layer. For example, the variations in aerosol loading can be compared to other key parameters of the atmosphere retrieved from the same SOIR spectra such as water and SO2 composition or temperature. In addition, a microphysical model is being developed that will calculate the time dependent haze particle size distributions assuming an initial size distribution of background sulphate aerosols. The model will simulate the formation, growth, evaporation, and sedimentation of particles. Results of this on-going research will be presented and discussed. References : Belyaev, D.A., F. Montmessin, J.-L. Bertaux

  12. Remote sensing of mesospheric dust layers using active modulation of PMWE by high-power radio waves

    NASA Astrophysics Data System (ADS)

    Mahmoudian, A.; Mohebalhojeh, A. R.; Farahani, M. M.; Scales, W. A.; Kosch, M.

    2017-01-01

    This paper presents the first study of the modulation of polar mesospheric winter echoes (PMWE) by artificial radio wave heating using computational modeling and experimental observation in different radar frequency bands. The temporal behavior of PMWE response to HF pump heating can be employed to diagnose the charged dust layer associated with mesospheric smoke particles. Specifically, the rise and fall time of radar echo strength as well as relaxation and recovery time after heater turn-on and turnoff are distinct parameters that are a function of radar frequency. The variation of PMWE strength with PMWE source region parameters such as electron-neutral collision frequency, photodetachment current, electron temperature enhancement ratio, dust density, and radius is considered. The comparison of recent PMWE measurements at 56 MHz and 224 MHz with computational results is discussed, and dust parameters in the PMWE generation regime are estimated. Predictions for HF PMWE modification and its connection to the dust charging process by free electrons is investigated. The possibility for remote sensing of dust and plasma parameters in artificially modified PMWE regions using simultaneous measurements in multiple frequency bands are discussed.

  13. On the kinetic and thermal fluctuations of gravity waves in the strato- and mesosphere as observed by Doppler lidar

    NASA Astrophysics Data System (ADS)

    Baumgarten, G.; Fiedler, J.; Hildebrand, J.; Höffner, J.; Luebken, F. J.; Strelnikova, I.

    2016-12-01

    The observation of wind and temperature in the stratosphere and mesosphere is crucial for understanding the dynamics in the middle atmosphere. Especially wind measurements are a challenging task. Only very few methods are capable to derive winds and temperatures in the entire stratosphere and mesosphere with vertical and temporal resolutions reasonable for gravity-wave studies. The Doppler Rayleigh/Mie/Raman lidar at the ALOMAR research station located in Northern Norway (69N, 16E) is capable to observe very variably dynamical situations at the edge of the polar vortex. The observations are performed even under sunlit conditions, which is essential for measuring atmospheric perturbations over several days and during summer at this location. We will present evidence for persistent inertia gravity wave signatures in horizontal wind and temperature and also show that they repeatedly occur as observed in the winters from 2012 to 2015. The measurements are of high quality from 20 km to about 80 km altitude during night and up to about 70 km during daytime. Both the kinetic and potential gravity-wave energy density can be derived and yield information about ensemble mean properties of gravity waves. We will present results from our analysis ranging from 5 minute temporal and 150 m vertical resolution and show that strong vertical and horizontal gradients are frequently observed. Such gradients challenge our understanding of wave propagation to the upper atmosphere and give rise to study wave-wave interactions in the winter stratopause region.

  14. Correlation between mesospheric ozone and Energetic Particle Precipitation over Troll, Antarctica in the years 2008 and 2009

    NASA Astrophysics Data System (ADS)

    Daae, M.; Espy, P. J.; Nesse Tyssøy, H.; Newnham, D. A.

    2013-12-01

    The British Antarctic Survey radiometer stationed at Troll, Antarctica (72S, 2.5E, L=4.76) measured ozone in the lower mesosphere and upper stratosphere from February 2008 until February 2010. By looking at anomalies in the polar-winter nighttime ozone, we are able to quantify the influence of Energetic Particle Precipitation (EPP) on ozone during these two years. Time-lagged correlations between geomagnetic indices (AE, Kp and Dst) and ozone anomalies as a function of height have been calculated to quantify which of the indices best accounts for the variability in the ozone. In addition, the MEPED instruments aboard the NOAA satellites have been used to quantify the EPP flux precipitating over Troll. Since the solar activity in 2008 undergoes a strong periodicity, which is linked to rotating coronal holes, this periodicity is also manifested in the EPP and the geomagnetic indices. A correlation analysis between the ozone over Troll and the periodic solar activity that is reflected in the EPP is also carried out, resulting in a statistical quantification of the EPP effects on mesospheric ozone as measured over Troll, Antarctica.

  15. Comparison of wind measurements in the troposphere and mesosphere by VHF/MF radars and in-situ techniques

    NASA Astrophysics Data System (ADS)

    Engler, N.; Singer, W.; Latteck, R.; Strelnikov, B.

    2008-11-01

    Radar wind observations at frequencies between 1.98 and 53.5 MHz obtained at polar latitudes were compared to in-situ wind measurements by radiosondes at tropospheric altitudes and to winds from falling spheres at mesospheric altitudes. Comparisons are shown for several campaigns of radiosonde and falling sphere observations. The radar wind directions agree well to the radiosonde and falling sphere observations and are highly correlated. The winds estimated from radar measurements are less than the radiosonde data by about 15% for spaced antenna observations and by about 10% for the Doppler beam swinging experiment. At mesospheric altitudes the spaced antenna winds obtained from the wide-beam Andenes MF radar are underestimated in the order of 35% and winds from the narrow-beam Saura MF radar are underestimated by about 20% compared to falling sphere winds at altitudes between 70 and 80 km. Furthermore, the relation between wind measurements using narrow-beam and wide-beam antenna arrangements for the MF radars is discussed and VHF radar observations are compared to the wide-beam MF radar.

  16. Wintertime Polar Ozone Evolution during Stratospheric Vortex Break-Down

    NASA Astrophysics Data System (ADS)

    Tweedy, O.; Limpasuvan, V.; Smith, A. K.; Richter, J. H.; Orsolini, Y.; Stordal, F.; Kvissel, O.

    2011-12-01

    Stratospheric Sudden Warming (SSW) is characterized by the rapid warming of the winter polar stratosphere and the weakening of the circumpolar flow. During the onset of a major SSW (when the circumpolar flow reverses direction), the warm stratopause layer (SL) descends from its climatological position to the mid-stratosphere level. As the vortex recovers from SSW, a "new" SL forms in the mid-mesosphere region before returning to its typical level. This SL discontinuity appears in conjunction with enhanced downward intrusion of chemical species from the lower thermosphere/upper mesosphere to the stratosphere. The descended species can potentially impact polar ozone. In this study, the NCAR's Whole Atmosphere Community Climate Model (WACCM) is used to investigate the behavior of polar ozone related to major SSWs. Specifically, dynamical evolution and chemistry of NOx, CO, and O3 are examined during three realistic major SSWs and compared with a non-SSW winter season. The simulated (zonal-mean) polar ozone distribution exhibits a "primary" maximum near 40 km, a "secondary" maximum between 90-105 km, and a "tertiary" maximum near 70 km. The concentration of the secondary maximum reduces by ~1.5 parts per million by volume (ppmv) as the vortex recovers and the upper mesospheric polar easterlies return. Enhanced downwelling above the newly formed SL extends up to just above this secondary maximum (~110 km). With an averaged concentration of 2 ppmv, the tertiary ozone maximum layer displaces upward with enhanced upwelling during SSW in conjunction with the lower mesospheric cooling. The downward propagation of the stratospheric wind reversal is accompanied by CO intrusion toward the lowermost stratosphere and anomalous behavior in the primary ozone maximum. Overall, the major SSW, SL, and polar ozone evolution mimic recently reported satellite observations.

  17. MAARSY - the new MST radar on Andøya: first results of spaced antenna and Doppler measurements of atmospheric winds in the troposphere and mesosphere using a partial array

    NASA Astrophysics Data System (ADS)

    Stober, G.; Latteck, R.; Rapp, M.; Singer, W.; Zecha, M.

    2012-09-01

    MST radars have been used to study the troposphere, stratosphere and mesosphere over decades. These radars have proven to be a valuable tool to investigate atmospheric dynamics. MAARSY, the new MST radar at the island of Andøya uses a phased array antenna and is able to perform spaced antenna and Doppler measurements at the same time with high temporal and spatial resolution. Here we present first wind observations using the initial expansion stage during summer 2010. The tropospheric spaced antenna and Doppler beam swinging experiments are compared to radiosonde measurements, which were launched at the nearby Andøya Rocket Range (ARR). The mesospheric wind observations are evaluated versus common volume meteor radar wind measurements. The beam steering capabilities of MAARSY are demonstrated by performing systematic scans of polar mesospheric summer echoes (PMSE) using 25 and 91 beam directions. These wind observations permit to evaluate the new radar against independent measurements from radiosondes and meteor radar measurements to demonstrate its capabilities to provide reliable wind data from the troposphere up to the mesosphere.

  18. [Review] Polarization and Polarimetry

    NASA Astrophysics Data System (ADS)

    Trippe, Sascha

    2014-02-01

    Polarization is a basic property of light and is fundamentally linked to the internal geometry of a source of radiation. Polarimetry complements photometric, spectroscopic, and imaging analyses of sources of radiation and has made possible multiple astrophysical discoveries. In this article I review (i) the physical basics of polarization: electromagnetic waves, photons, and parameterizations; (ii) astrophysical sources of polarization: scattering, synchrotron radiation, active media, and the Zeeman, Goldreich-Kylafis, and Hanle effects, as well as interactions between polarization and matter (like birefringence, Faraday rotation, or the Chandrasekhar-Fermi effect); (iii) observational methodology: on-sky geometry, influence of atmosphere and instrumental polarization, polarization statistics, and observational techniques for radio, optical, and X/γ wavelengths; and (iv) science cases for astronomical polarimetry: solar and stellar physics, planetary system bodies, interstellar matter, astrobiology, astronomical masers, pulsars, galactic magnetic fields, gamma-ray bursts, active galactic nuclei, and cosmic microwave background radiation.

  19. A superposed epoch study of the effects of solar wind stream interface events on the upper mesospheric and lower thermospheric temperature

    NASA Astrophysics Data System (ADS)

    Ogunjobi, O.; Sivakumar, V.; Sivla, W. T.

    2014-11-01

    The response of mesosphere and lower thermosphere (MLT) temperature to energetic particle precipitation over the Earth’s polar regions is not uniform due to complex phenomena within the MLT environment. Nevertheless, the modification of MLT temperatures may require an event-based study to be better observed. This work examines the influence of precipitation, triggered by solar wind stream interfaces (SI) event from 2002 to 2007, on polar MLT temperature. We first test the relationship between the ionospheric absorption measured by the SANAE IV (South African National Antarctic Expedition IV) riometer and the layer of energetic particle precipitation from POES (Polar Orbiting Environmental Satellites). The combined particle measurements from POES 15, 16, 17 and 18 were obtained close in time to the pass of the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) temperature retrieval. Here, a superposed epoch technique is described and implemented to obtain average temperature profiles during SI-triggered particle precipitation. The superposed epoch average shows no significant temperature decrease below 100 km prior to the onset of SI-triggered precipitation, whereas a clear superposed average temperature decrease is observed at 95 km after the SI impact. A case study of SI event also yields similar observations. Results indicate that cooling effects due to the production of mesospheric odd hydrogen might be major contributors to temperature decrease under compressed solar wind stream.

  20. Mesospheric observations by a forward scattering meteor radar basic setup

    NASA Astrophysics Data System (ADS)

    Madkour, Waleed; Yamamoto, Masa-yuki

    2016-08-01

    The durations of radio echo signals scattered from meteor ionized trails might not show a consistent increase corresponding to higher density trails due to the rapid removal of meteor ions at certain heights. Several studies have concluded the dominant role of the secondary ozone layer over diffusion in the removal of the meteor trails below 95 km through chemical oxidization of the meteor ions. Using a basic setup configuration of a forward scattering receiver, a trial to observe the mesospheric ozone concentration was performed by analyzing the meteor echo duration distributions. The forward scattered meteor echoes have the advantage of long durations that can enable observing the transition from the diffusion-removal regime to the chemistry-removal regime. The cumulative meteor echo duration distribution of two meteor showers, the Perseids and the Geminids, were analyzed over 10 years and the chemistry-removal regime in each shower was observed. The knee duration position at which a drop in the number of long overdense meteor echoes starts differed by around 30 seconds between the two showers. As the secondary ozone concentration is inversely related to the solar activity level, the Geminids 2011 corresponding to a high solar activity level showed a significant higher counts of long duration echoes compared to the Geminids 2006 during a low activity level, with the knee position shifted to longer duration. The knee positions obtained during the two distinct meteor showers and the two half solar cycle points are generally in agreement with the mesospheric ozone conditions expected in each case. However, continuous data record is required for the other meteor showers and the sporadic meteors at different heights to observe the mesospheric ozone concentration vertically and the full 11-years solar cycle.

  1. Submillimeter mapping of mesospheric minor species on Venus with ALMA

    NASA Astrophysics Data System (ADS)

    Encrenaz, Therese; Moreno, Raphael; Moullet, Arielle; Lellouch, Emmanuel; Fouchet, Thierry

    2014-05-01

    ALMA offers a unique opportunity to map mesospheric species on Venus. During Cycle 0, we have observed Venus on November 14 and 15, 2011, using the compact configuration of ALMA. The diameter of Venus was 11 arcsec and the illumination factor was about 90 percent. Maps of CO, SO, SO2, and HDO have been built from transitions recorded in the 335-347 GHz frequency range. The mesospheric thermal profile has been inferred using the CO transition at 345.795 GHz. From the integrated spectrum of SO recorded on Nov. 14 at 346.528 GHz, we find that the best fit is obtained with a cut-off in the SO vertical distribution at about 88 km and a mean mixing ratio of about 8.0 ppb above this level. In the case of SO2, as for SO, we find that the best fit is obtained with a cut-off at about 88 km; the SO2 mixing ratio above this level is about 12 ppb. The map of HDO is retrieved from the 335.395 GHz transition. Assuming a typical D/H ratio of 200 times the terrestrial value in the mesosphere of Venus, we find that the disk averaged HDO spectrum is consistent with a H2O mixing ratio of about 2.5 ppm, constant with altitude. Our results are in good agreement with previous single dish submillimeter observations (Sandor and Clancy, Icarus 177, 129, 2005; Gurwell et al. Icarus 188, 288, 2007; Sandor et al. Icarus 208, 49, 2010; Icarus 217, 836, 2012), as well as with the predictions of photochemical models (Zhang et al. Icarus 217, 714, 2012).

  2. Observational Implications of a New Model of Mesospheric Bores

    NASA Astrophysics Data System (ADS)

    Picard, R. H.; Cohen, E.; Dewan, E. M.; Winick, J. R.; Taylor, M. J.; She, C. Y.

    2004-05-01

    We examine the observational implications of a new numerical model of the generation and propagation of mesospheric bores. The bores develop as long-wave excitations in mesospheric wave ducts, formed by the temperature and wind structure, in much the same way as they do in the tropospheric boundary-layer duct. However, while the boundary-layer duct has a clamped ground boundary (zero vertical displacement), the embedded mesospheric duct has two free boundaries, which results in some differences in behavior. With a separability assumption valid in the long-wave limit, the fluid equations separate into a product of solutions of the Taylor-Goldstein equation describing the vertical dependence of the mode function and of the Benjamin-Davis-Ono (BDO) equation describing the horizontal and time behavior. We compare results of the numerical model with the analytic model of Dewan and Picard (1998) that is based on Lighthill's channel-bore solutions. The numerical model leads to predictions of new and/or as-yet-unobserved phenomena, including (1) the possible existence of bores in Doppler ducts, (2) the existence of a fast sinuous-mode bore with no channel-bore analogue having phase speeds of 150-180 m/s, and (3) the possibility of foaming or turbulent (non-undular) bores. Following Christie (1989), we model the turbulent dissipation processes in the latter case by including a Burgers-type term in the BDO equation. We also compare model predictions with recent bore observations accompanied by simultaneous lidar data [Smith et al., 2001; She et al., 2004].

  3. Metals in the mesosphere: meteoroids, satellite retrievals and modelling

    NASA Astrophysics Data System (ADS)

    Dawkins, E.; Plane, J. M.; Chipperfield, M.; FENG, W.; Gumbel, J.; Hedin, J.; Höffner, J.; Friedman, J. S.

    2013-12-01

    Changes in the mesosphere may be an important signal of climate change and there is increasing evidence that accurate simulations of changes to the Earth's climate require models with a well resolved and accurate stratosphere and mesosphere. Following the ablation of meteoroids, the resulting metal species which are injected into the mesosphere/lower thermosphere region (80-110 km) offer a unique way of observing this region and of testing the accuracy of climate models in this domain. An earlier sodium retrieval algorithm has been extended, and modified to retrieve potassium densities using data from the OSIRIS spectrometer on-board the Odin satellite. Here we present an overview of the new potassium retrieval scheme, along with the first ever climatology of the global potassium layer from space for 2004-2012. These layers have been validated using lidar data and successfully capture the unusual semi-annual seasonal behaviour of potassium, which is starkly different to the other metals. Unlike sodium and iron which both display early wintertime density maxima, potassium also displays a summertime maximum which points to some unique and surprising features in the chemistry and the way it interacts with other atmospheric species. A detailed potassium chemistry scheme, developed by a team at Leeds (modules for Na, Fe, Ca, Si and Mg already added), has now been included in a version of the NCAR Whole Atmosphere Community Climate Model (WACCM). The annual, latitudinal and long-term variation of these modelled potassium layers are compared with the retrieved datasets to evaluate model chemistry and dynamics.

  4. A New Measurement Capability Using the CEDAR Mesospheric Temperature Mapper

    NASA Astrophysics Data System (ADS)

    Taylor, M. J.; Pendleton, W. R.

    2001-12-01

    The CEDAR Mesospheric Temperature Mapper (MTM) was developed at Utah State University in 1996/7 as part of the CEDAR Phase III initiative for new research instrumentation. The MTM uses a sensitive bare CCD detector to obtain high signal-to-noise ratio ( ~100:1) images of selected emission lines in the near infrared OH (6,2) band to determine intensity and temperature perturbations induced by a wide range of atmospheric waves (periods ~10 min - ~10 hrs) with a precision of better than 2K in 3-min (or 0.5 K in 30 min). The high precision and stability of the MTM make it very well suited for long-term field measurements and extensive data sets have been obtained alongside two powerful Na lidar systems: at Ft Collins, CO (1997/98), and at the Starfire Optical Range, NM (1998/2000). These joint data sets have revealed a wealth of new information on gravity wave and tidal propagation at mesospheric heights and to date our analyses have focused on characterizing the 8-hr tide at mid-latitudes and the identification of a fall equinox transition signature associated with the penetration of stationary planetary wave energy into the upper mesosphere during the seasonal reversal of the stratospheric wind field. In this presentation we will summarize these results and will then focus on recent measurements of wave propagation (phase) and growth (amplitude) from Bear Lake Observatory, UT using an enhanced MTM capable of measuring wave signatures in the both the near infrared OH (peak altitude ~87 km) and the 02(0,1) (altitude ~94 km) emission layers. New observations using the enhanced MTM are planned as part of the NASA/NSF TIMED coordinated ground-based measurements program and the AFOSR/NSF Maui-MALT initiative.

  5. Upper mesosphere temperatures from OH(asterisk)-emissions

    NASA Astrophysics Data System (ADS)

    Offermann, D.; Gerndt, R.

    Ground-based NIR spectrometers were operated at Wuppertal (FRG) and Oslo to detect seasonal and latitudinal mesospheric temperature variations by measuring the emission of metastable OH molecules. The measurement accuracy was + or - 2.5 K. The results are compared with various atmosphere models (Cole and Kantor, 1972; Barnett and Corney, 1985; Groves, 1985) in graphs, and good general agreement is found with the two 1985 models, with smaller discrepancies in winter than in summer. The relevance of the OH-based data for the 1986 COSPAR International Reference Atmosphere is briefly indicated.

  6. In situ measurements of the mesosphere and stratosphere

    NASA Technical Reports Server (NTRS)

    Crosky, C.

    1976-01-01

    The operation of a subsonic, Gerdien condenser probe for in situ measurements of the mesosphere and stratosphere is presented. The inclusion of a flashing Lyman alpha ultraviolet source provides an artifically produced ionization of particular constituents. Detailed theory of operation is presented and the data results from two flights are shown. A great deal of fine structure in mobility is observed due to the presence of various hydrated positive ions. The effect of the Lyman alpha source in the 35 km region was to dissociate a light hydrate ion rather than produce additional ionization. At the 70 km region, photodissociation of the heaviest ions (probably ice crystals) was also observed.

  7. The Polar Summer MLT Plasma Environment as Seen by the DROPPS Sounding Rockets

    NASA Technical Reports Server (NTRS)

    Assis, Michael P.; Goldberg, Richard A.; Webb, Phillip A.; Pesnell, William D.; Voss, H. D.

    2006-01-01

    During early July, 1999, the DROPPS (Distribution and Role of Particles in the Polar Summer Mesosphere) campaign launched two rocket payloads whose purpose was to study the polar summer MLT (mesosphere and lower thermosphere), particularly PMSEs (polar mesospheric summer echoes) and PMCs (polar mesospheric clouds). The rockets were launched from the Anderya Rocket Range in Norway the nights of the 5th and 14th of July. Both payloads included a front-mounted PID (Particle Impact Detector) consisting of charge and mass telescopes to measure aerosol and dust mass distributions. Ice particles of nanometer size are believed to be responsible for PMSEs through the process of electron scavenging. Evidence for this process is suggested, for example, by the presence of an electron "biteout" simultaneously measured by several instruments at an altitude of approx. 82 - 87km during the first DROPPS launch. This presentation will characterize similarities and differences between both flights as seen by the charge and mass telescopes, starting at launch until the loss of data on the downleg of each flight. Various stages of the flights will be considered in detail, such as the PMSE layer and the apogee at 117 km, as well as the calibration of the data before launch.

  8. The Polar Summer MLT Plasma Environment as seen by the DROPPS Sounding Rockets

    NASA Technical Reports Server (NTRS)

    Assis, Michael P.; Goldberg, Richard A.; Webb, Phillip; Pesnell, W. Dean; Voss, Henry D.

    2006-01-01

    During early July, 1999, the DROPPS (Distribution and Role of Particles in the Polar Summer Mesosphere) campaign launched two rocket payloads whose purpose was to study the polar summer MLT (mesosphere and lower thermosphere), particularly PMSEs (polar mesospheric summer echoes) and PMCs (polar mesospheric clouds). The rockets were launched from the And(\\o)ya Rocket Range in Norway the nights of the 5th and 14th of July. Both payloads included a front-mounted PID (Particle Impact Detector) consisting of charge and mass telescopes to measure aerosol and dust mass distributions. Ice particles of nanometer size are believed to be responsible for PMSEs through the process of electron scavenging. Evidence for this process is suggested, for example, by the presence of an electron "biteout" simultaneously measured by several instruments at an altitude of $\\sim$82-87 km during the first DROPPS launch. This presentation will characterize similarities and differences between both flights as seen by the charge and mass telescopes, starting at launch until the loss of data on the downleg of each flight. Various stages of the flights will be considered in detail, such as the PMSE layer and the apogee at 117 km, as well as the calibration of the data before launch.

  9. Simultaneous Observations fo Polar Stratospheric Clouds and HNO3 over Scandinavia in January, 1992

    NASA Technical Reports Server (NTRS)

    Massie, S. T.; Santee, M. L.; Read, W. G.; Grainger, R. G.; Lambert, A.; Mergenthaler, J. L.; Dye, J. E.; Baumbardner, D.; Randel, W. J.; Tabazadeh, A.; hide

    1996-01-01

    Simultaneous observations of Polar Stratospheric Cloud aerosol extinction and HNO3 mixing ratios over Scandinavia are examined for January 9-10, 1992. Data measured by the Microwave Limb Sounder (MLS), Cryogenic Limb Array Etalon, Spectrometer (CLAES), and Improved Stratospheric and Mesospheric Sounder (ISAMA) experiments on the Upper Atmosphere Research Satellite (UARS) are examined at locations adjacent to parcel trajectory positions.

  10. Identification of water-soluble polar organics in air and vehicular emitted particulate matter using ultrahigh resolution mass spectrometry and Capillary electrophoresis - mass spectrometry.

    NASA Astrophysics Data System (ADS)

    Schmitt-Kopplin, P.; Yassine, M.; Gebefugi, I.; Hertkorn, N.; Dabek-Zlotorzynska, E.

    2009-04-01

    The effects of aerosols on human health, atmospheric chemistry, and climate are among the central topics in current environmental health research. Detailed and accurate measurements of the chemical composition of air particulate matter (PM) represent a challenging analytical task. Minute sample amounts are usually composed of several main constituents and hundreds of minor and trace constituents. Moreover, the composition of individual particles can be fairly uniform or very different (internally or externally mixed aerosols), depending on their origin and atmospheric aging processes (coagulation, condensation / evaporation, chemical reaction). The aim of the presentation was the characterization of the organic matter (OM) fraction of environmental aerosols which is not accessible by GC-methods, either because of their high molecular weight, their polarity or due to thermal instability. We also describe the main chemical characteristics of complexe oligomeric organic fraction extracted from different aerosols collected in urban and rural area in Germany and Canada. Mass spectrometry (MS) became an essential tool used by many prominent leaders of the biological research community and the importance of MS to the future of biological research is now clearly evident as in the fields of Proteomics and Metabolomics. Especially Fourier Transform Ion Cyclotron Mass Spectrometry (ICR-FT/MS) is an ultrahigh resolution MS that allows new approach in the analysis of complex mixtures. The mass resolution (< 200 ppb) allowed assigning the elemental composition (C, H, O, N, S…) to each of the obtained mass peaks and thus already a description of the mixture in terms of molecular composition. This possibility is used by the authors together with a high resolution separation method of charged compounds: capillary electrophoresis. A CE-ESI-MS method using an ammonium acetate based background electrolyte (pH 4.7) was developed for the determination of isomeric benzoic acids in

  11. Temperature, shape, and phase of mesospheric ice from Solar Occultation for Ice Experiment observations

    NASA Astrophysics Data System (ADS)

    Hervig, Mark E.; Gordley, Larry L.

    2010-08-01

    The temperature and shape of ice particles in polar mesospheric clouds (PMCs) were determined using observations near 3 μm wavelength from the Solar Occultation for Ice Experiment (SOFIE). The resulting ice temperatures are 5-20 K colder than the current SOFIE temperatures retrieved from CO2 transmission measurements. Particle shape is described using oblate spheroids, and the axial ratios determined in this study are slightly more spherical than previous results obtained using SOFIE observations assuming constant temperature (1.9 at the altitude of peak mass density compared to 2.3 previously). Using ice temperatures in an equilibrium PMC model results in ice mass densities that are much higher than observed. SOFIE observations indicate that the amount of H2O that can enter the ice phase is related to ice concentration, suggesting that ice nucleation plays an important role in determining PMC formation and variability. This result may also imply that the neglect of transient phenomena in the equilibrium PMC model may be a large source of error. SOFIE observations do not support the existence of amorphous ice particles near the summer mesopause but rather indicate that cubic ice is ubiquitous.

  12. Global observations of the mesospheric sodium layer from the OSIRIS instrument on ODIN

    NASA Astrophysics Data System (ADS)

    Fan, Z.; Plane, J.; Gumbel, J.; Llywellyn, E.; She, C.

    Limb-scanning observations of the Na D -line radiance at 589 nm in the earth s dayglow made from the OSIRIS instrument on the ODIN satellite have been used to retrieve absolute Na density profiles These have been ground-truthed using a Na lidar at Ft Collins Colorado Two years of data 2003 2004 have been analyzed to characterize the seasonal and latitudinal dependence of the global Na layer This paper will first describe the retrieval algorithm and error analysis and then discuss some of the important findings First is a pronounced diurnal variation in the equatorial region with the morning Na density being much lower than in early evening This is almost certainly caused by the effect of the strong diurnal tide on the local atomic oxygen density Second there is substantial depletion of Na in the presence of polar mesospheric clouds at high latitudes during summer which leads to a very marked seasonal variation in the layer Finally the vertical resolution in the retrieved profiles is good enough to resolve sporadic or sudden Na layers SSLs The global probability distribution of SSLs is rather unexpected with a much higher probability at mid- to high latitudes in the southern hemisphere

  13. HRDI Observations of Inertia-Gravity Waves in the Mesosphere and Lower Thermosphere

    NASA Technical Reports Server (NTRS)

    Lieberman, Ruth S.

    1999-01-01

    Vertical profiles of High-resolution Doppler imager (HRDI) mesospheric winds have small-scale structure (vertical wavelengths between 10 and 20 km) that is virtually always present. Fourier analysis of HRDI zonal and meridional wind profiles have been carried out, and the spectral characteristics are sorted by latitude, month and local time. Power spectral density (PSD) exhibits a universal exp(-km) structure in the 10-20km wavelength regime, with K lying between 2 and 3. The observed PSD for wavelengths between 10 and 20 km is a factor of 3 higher than a null spectrum constructed from HRDI reported error bars multiplied by randomly varying numbers between -1 and +1. Stokes parameters were consolidated by month into Northern and Southern hemisphere middle and high latitudes belts (40-72 degrees), tidal belts (32-16 degrees) and a tropical belt (8S-8N). Vertical waves between 10 and 15 km in wavelength are about 10-15% polarized everywhere. The inferred propagation direction in the middle and high latitude Southern hemisphere is predominantly meridional during solstice, and significantly more zonal during equinoxes. In the tropical belt, the wave orientations are nearly North-South during solstices, with a slightly higher east-west component during equinox. In the tidal belts where the background wind includes a strong meridional tidal wind, the preferred wave orientation has a significant zonal component during equinox. These findings are consistent with the interpretation of wave filtering by the background wind.

  14. Seasonal variation of mesospheric waves at northern middle and high latitudes

    NASA Astrophysics Data System (ADS)

    Hoffmann, Peter; Becker, Erich; Singer, Werner; Placke, Manja

    2010-09-01

    The seasonal variation of the wave activity in the mesosphere/lower thermosphere is investigated using wind measurements with meteor and MF radars at Juliusruh (55°N, 13°E) and Andenes (69°N, 16°E), as well as on the basis of the simulated annual cycle using a gravity-wave resolving mechanistic general circulation model. For the observations, proxies for the activity of gravity waves (GWs) and waves with longer periods are computed from wind variances for defined bandwidths. Our corresponding proxy for the simulated GWs is the non-rotational kinetic energy due to the resolved mesoscales. Both observational and computational results show the strongest GW energy during winter and a secondary maximum during summer. Additional observational analysis of short-period GWs yields a more pronounced summer maximum. The semi-annual variation is consistent with the selective filtering of westward and eastward GWs by the mean zonal wind. The latitudinal dependence during summer is characterized by stronger GW energy between 65 and 85 km at middle latitudes than at polar latitudes, and a corresponding upward shift of the wind reversal towards the pole which is also reflected by the simulated GW drag. Also the observed oscillations with periods from 2 to 4 days show a latitudinal dependence and a clear seasonal cycle which is related to the mean zonal wind shear.

  15. Joule heating in the mesosphere and thermosphere during the July 13, 1982, solar proton event

    NASA Technical Reports Server (NTRS)

    Roble, R. G.; Emery, B. A.; Garcia, R. R.; Killeen, T. L.; Hays, P. B.; Reid, G. C.; Solomon, S.; Evans, D. S.; Spencer, N. W.; Brace, L. H.

    1987-01-01

    The solar proton event of July 13, 1982 produced considerable ionization in the polar-cap mesosphere. Energetic solar proton fluxes were measured by the NOAA-6 satellite. The DE-2 satellite measured the low-energy electrons, the ion drift velocity, and other atmospheric and ionospheric properties during the event in the region of the measured maximum electric field (189 mV/m at 2215 UT near 60 deg N), a Joule heating rate of 1-3 K/day is calculated between 70 and 80 km, exceeding the heating due to ozone absorption at noon in the summer hemisphere in that altitude range. The Joule heating rate above 90 km greatly exceeded 20 K/day. The calculated height-integrated Joule heating rate above 100 km in the same region exceeded 400 ergs/sq cm sec, and DE-2 near 350 km measured neutral winds of nearly 1000 m/s and neutral gas temperatures of over 2000 K. The overall ionospheric structure calculated below the DE-2 satellite is described.

  16. The Role and Importance of Gravity Waves in the Mesosphere and Thermosphere of Mars

    NASA Astrophysics Data System (ADS)

    Medvedev, A. S.; Yigit, E.

    2015-12-01

    Gravity waves are generated in the lower Martian atmosphere by flow over topography, strong convection, and volatile instabilities of weather systems. Upward propagation and the resulting dissipation of gravity waves produce a substantial amount of momentum deposition and heating/cooling rates in the middle atmosphere (50-100 km) and above the mesopause (~100 km). These waves have horizontal wavelengths usually smaller than the conventional resolution of general circulation models (GCMs), and, thus, their effects have to be parameterized. Simulations with the Max Planck Institute Mars GCM using the interactively implemented nonlinear spectral parameterization have revealed a very important role of gravity waves in the dynamics of the middle and upper atmosphere of Mars. They close, and even reverse, the zonal jets, enhance the meridional circulation and middle atmosphere polar warmings, facilitate the formation of CO2 ice clouds, and modulate the upper atmospheric response to dust storms. Gravity wave-induced cooling is as strong in the mesosphere and thermosphere as the major radiative cooling mechanism - the radiative transfer in the IR bands of CO2 molecules, and can explain the observed temperatures in the lower thermosphere.

  17. The Optical Mesosphere Thermosphere Imagers (OMTIs) for network measurements of aurora and airglow

    NASA Astrophysics Data System (ADS)

    Shiokawa, K.; Hosokawa, K.; Sakaguchi, K.; Ieda, A.; Otsuka, Y.; Ogawa, T.; Connors, M.

    2009-06-01

    The Optical Mesosphere Thermosphere Imagers (OMTIs) currently consist of eight all-sky cooled-CCD imagers and several interferometers and spectrometers. They are making routine observations of aurora and airglow in Japan, Australia, Indonesia, and Canada. Here we show recent results of OMTIs particularly from the two Canadian stations at Resolute Bay (RSB) and Athabasca (ATH). At RSB, we observe polar-cap plasma patches almost always during southward IMF periods. From two-dimensional cross-correlation analyses, we determine velocity vectors of the patches, which indicates the ionospheric convection vector, showing high correlation with the IMF-By and-Bz variations. At ATH, we often observe isolated proton arcs and Stable Auroral Red (SAR) arcs, which are located equatorward of the auroral oval. The appearance of the isolated proton arcs is highly correlated with the Pc 1 geomagnetic pulsations measured simultaneously at ATH, suggesting interactions between the electromagnetic ion cyclotron (EMIC) waves and protons in the vicinity of the plasmapause and the ring current. Similar interactions without waves are also suggested for the SAR arcs, which appear after the substorm expansion phase even without geomagnetic storms. These observations show promising capability to monitor magnetospheric processes from the ground stations, which would contribute to the future satellite projects, such as THEMIS, ERG, and Scope/Xscale.

  18. Joule heating in the mesosphere and thermosphere during the July 13, 1982, solar proton event

    NASA Technical Reports Server (NTRS)

    Roble, R. G.; Emery, B. A.; Garcia, R. R.; Killeen, T. L.; Hays, P. B.; Reid, G. C.; Solomon, S.; Evans, D. S.; Spencer, N. W.; Brace, L. H.

    1987-01-01

    The solar proton event of July 13, 1982 produced considerable ionization in the polar-cap mesosphere. Energetic solar proton fluxes were measured by the NOAA-6 satellite. The DE-2 satellite measured the low-energy electrons, the ion drift velocity, and other atmospheric and ionospheric properties during the event in the region of the measured maximum electric field (189 mV/m at 2215 UT near 60 deg N), a Joule heating rate of 1-3 K/day is calculated between 70 and 80 km, exceeding the heating due to ozone absorption at noon in the summer hemisphere in that altitude range. The Joule heating rate above 90 km greatly exceeded 20 K/day. The calculated height-integrated Joule heating rate above 100 km in the same region exceeded 400 ergs/sq cm sec, and DE-2 near 350 km measured neutral winds of nearly 1000 m/s and neutral gas temperatures of over 2000 K. The overall ionospheric structure calculated below the DE-2 satellite is described.

  19. All Aboard! The Polar Express Is Traveling to Science--Understanding the States of Matter While Differentiating Instruction for Young Learners

    ERIC Educational Resources Information Center

    Vowell, Julie; Phillips, Marianne

    2015-01-01

    This standards-based science lesson introduces young learners to scientific inquiry and critical thinking by using activities to demonstrate three phases of matter (solid, liquid, and gas). By learning about the states of matter through a 5E instructional approach, students are encouraged to observe changes in the states of matter and to discuss…

  20. All Aboard! The Polar Express Is Traveling to Science--Understanding the States of Matter While Differentiating Instruction for Young Learners

    ERIC Educational Resources Information Center

    Vowell, Julie; Phillips, Marianne

    2015-01-01

    This standards-based science lesson introduces young learners to scientific inquiry and critical thinking by using activities to demonstrate three phases of matter (solid, liquid, and gas). By learning about the states of matter through a 5E instructional approach, students are encouraged to observe changes in the states of matter and to discuss…

  1. Evidence of Meteor Smoke Particles as precursors for formation of mesospheric clouds on Mars

    NASA Astrophysics Data System (ADS)

    Määttänen, Anni; Listowski, Constantino

    2017-04-01

    Mesospheric clouds have been systematically observed in the Martian mesosphere for about a decade. Not all of the observations allow for the cloud composition to be defined. However, several observations have revealed clouds formed of CO2 ice crystals, although in some cases a water ice composition has been detected as well. The condensation of the main component of the atmosphere is a fairly unique phenomenon. Although the lower atmosphere of Mars is very dusty and rich in ice nuclei, the mesosphere should be fairly devoid of dust lifted from lower layers (due to weak probability of lifting to high altitudes and low atmospheric densities favouring sedimentation). A very interesting candidate as a source of ice nuclei in the mesosphere comes from a terrestrial analogue. Meteor Smoke Particles have been shown to play a role in the formation of the mesospheric clouds on the Earth, and in a recent modelling study we have been able to show that an exogenous source of ice nuclei is required in the Martian mesosphere to be able to model clouds with observed properties. We will present a short review of observations and a summary of the cloud properties, and then discuss the model results pointing towards Meteor Smoke Particles as a necessary ingredient for the formation of mesospheric clouds on Mars.

  2. Modeling Study of Mesospheric Planetary Waves: Genesis and Characteristics

    NASA Technical Reports Server (NTRS)

    Mayr, H. G.; Mengel, J. G.; Talaat, E. L.; Porter, H. S.; Chan, K. L.

    2003-01-01

    In preparation for the measurements from the TIMED mission and coordinated ground based observations, we discuss results for the planetary waves (PWs) that appear in our Numerical Spectral Model (NSM). The present model accounts for a tropospheric heat source in the zonal mean (m = 0), which reproduces qualitatively the observed zonal jets near the tropopause and the accompanying reversal in the latitudinal temperature variations. We discuss the PWs that are solely generated internally, i.e., without the explicit excitation sources related to tropospheric convection or topography. Our analysis shows that PWs are not produced when the zonally averaged heat source into the atmosphere is artificially suppressed, and that the PWs generally are significantly weaker when the tropospheric source is not applied. Instabilities associated with the zonal mean temperature, pressure and wind fields, which still need to be explored, are exciting PWs that have amplitudes in the mesosphere comparable to those observed. Three classes of PWs are generated in the NSM. (1) Rossby waves, (2) Rossby gravity waves propagating westward at low latitudes, and (3) Eastward propagating equatorial Kelvin waves. A survey of the PWs reveals that the largest wind amplitudes tend to occur below 80 km in the winter hemisphere, but above that altitude they occur in the summer hemisphere where the amplitudes can approach 50 meters per second. It is shown that the non-migrating tides in the mesosphere, generated by non-linear coupling between migrating tides and PWs, are significantly larger for the model with the tropospheric heat source.

  3. Bite-outs and other depletions of mesospheric electrons

    NASA Astrophysics Data System (ADS)

    Friedrich, Martin; Rapp, Markus; Plane, John M. C.; Torkar, Klaus M.

    2011-09-01

    The ionised mesosphere is less understood than other parts of the ionosphere because of the challenges of making appropriate measurements in this complex region. We use rocket borne in situ measurements of absolute electron density by the Faraday rotation technique and accompanying DC-probe measurements to study the effect of particles on the D-region charge balance. Several examples of electron bite-outs, their actual depth as well as simultaneous observations of positive ions are presented. For a better understanding of the various dependencies we use the ratio β/αi (attachment rate over ion-ion recombination coefficient), derived from the electron and ion density profiles by applying a simplified ion-chemical scheme, and correlate this term with solar zenith angle and moon brightness. The probable causes are different for day and night; recent in situ measurements support existing hypotheses for daytime cases, but also reveal behaviour at night hitherto not reported in the literature. Within the large range of β/αi values obtained from the analysis of 28 high latitude night flights one finds that the intensity of scattered sunlight after sunset, and even moonlight, apparently can photodetach electrons from meteoric smoke particles (MSP) and molecular anions. The large range of values itself can best be explained by the variability of the MSPs and by occasionally occurring atomic oxygen impacting on the negative ion chemistry in the night-time mesosphere under disturbed conditions.

  4. Bite-outs and other depletions of mesospheric electrons.

    PubMed

    Friedrich, Martin; Rapp, Markus; Plane, John M C; Torkar, Klaus M

    2011-09-01

    The ionised mesosphere is less understood than other parts of the ionosphere because of the challenges of making appropriate measurements in this complex region. We use rocket borne in situ measurements of absolute electron density by the Faraday rotation technique and accompanying DC-probe measurements to study the effect of particles on the D-region charge balance. Several examples of electron bite-outs, their actual depth as well as simultaneous observations of positive ions are presented. For a better understanding of the various dependencies we use the ratio β/αi (attachment rate over ion-ion recombination coefficient), derived from the electron and ion density profiles by applying a simplified ion-chemical scheme, and correlate this term with solar zenith angle and moon brightness. The probable causes are different for day and night; recent in situ measurements support existing hypotheses for daytime cases, but also reveal behaviour at night hitherto not reported in the literature. Within the large range of β/αi values obtained from the analysis of 28 high latitude night flights one finds that the intensity of scattered sunlight after sunset, and even moonlight, apparently can photodetach electrons from meteoric smoke particles (MSP) and molecular anions. The large range of values itself can best be explained by the variability of the MSPs and by occasionally occurring atomic oxygen impacting on the negative ion chemistry in the night-time mesosphere under disturbed conditions.

  5. Carbon Dioxide Ice Structure and Density in the Martian Mesosphere

    NASA Astrophysics Data System (ADS)

    Mangan, Thomas; Murray, Benjamin

    2016-04-01

    CO2 ice has been grown experimentally via deposition in order to mimic ice formation in Martian mesospheric CO2 clouds. This is achieved through the use of a low temperature and low pressure controlled stage mounted within an X-ray diffractomer (XRD). XRD patterns of CO2 deposited at temperatures of 80 - 130 K and pressures below 1 mbar were analysed using a Rietveld refinement method and fitted to a crystalline cubic structure (space group Pa3). This crystal structure is consistent with XRD patterns also taken of dry ice. CO2 ice densities were then determined from the refined lattice parameters across the 80 - 130 K range and extrapolated using literature values resulting in a temperature dependent density parameter valid over 80 - 195 K. This temperature dependent parameter for CO2 ice density was applied to nucleation, sedimentation and growth rates of CO2 ice particles under conditions relevant to the Martian mesosphere. The results were then compared to commonly used literature values, illustrating the need for the use of temperature dependent CO2 ice densities.

  6. A climatology of nitric oxide in the mesosphere and thermosphere

    NASA Astrophysics Data System (ADS)

    Global measurements of nitric oxide (NO) in the earth's upper atmosphere have now been obtained by two satellite experiments during the declining phases of the last two solar cycles. In the 1980's, NO was measured by the Solar Mesosphere Explorer while in the 1990's, NO has been observed by the Halogen Occultation Experiment (HALOE) on board the UARS satellite. The SME data cover the altitude range from 95 to 160 km and extend from pole to pole. The HALOE data used here cover the altitude range from 50 to 125 km and extend from 70N to 70S. Both datasets show a well defined decrease in NO during the decline of solar activity. Also, large perturbations due to auroral activity are seen at middle and high latitudes. In addition, the HALOE data show large increases in the high latitude winter mesosphere which are associated with downward transport from the thermosphere. This paper presents a reference NO model which is based upon the two datasets and which covers a wide range of solar, geomagnetic and seasonal conditions.

  7. Laboratory Studies of Vibrational Relaxation: Important Insights for Mesospheric OH

    NASA Astrophysics Data System (ADS)

    Kalogerakis, K. S.; Matsiev, D.

    2016-12-01

    The hydroxyl radical has a key role in the chemistry and energetics of the Earth's middle atmosphere. A detailed knowledge of the rate constants and relevant pathways for OH(high v) vibrational relaxation by atomic and molecular oxygen and their temperature dependence is absolutely critical for understanding mesospheric OH and extracting reliable chemical heating rates from atmospheric observations. We have developed laser-based experimental approaches to study the complex collisional energy transfer processes involving the OH radical and other relevant atmospheric species. Previous work in our laboratory indicated that the total removal rate constant for OH(v = 9) + O at room temperature is more than one order of magnitude larger than that for removal by O2. Thus, O atoms are expected to significantly influence the intensity and vibrational distribution extracted from the Meinel OH(v) emissions. We will report our most recent laboratory experiments that corroborate the aforementioned result for fast OH(v = 9) + O and provide important new insights on the mechanistic pathways involved. We will also highlight relevant atmospheric implications, including warranted revisions of current mesospheric OH models. Research supported by SRI International Internal R&D and NSF Aeronomy grant AGS-1441896. Previously supported by NASA Geospace Science grant NNX12AD09G.

  8. Nucleation of Mesospheric Cloud Particles: Model and Laboratory Results

    NASA Astrophysics Data System (ADS)

    Wilms, H.; Kirsch, A.; Rapp, M.; Duft, D.; Nachbar, M.; Leisner, T.

    2014-12-01

    Nucleation of mesospheric ice is assumed to occur on meteor smoke particles (MSP). Classical nucleation theory however includes several insufficiently known parameters when applied to the conditions at the mesopause for heterogeneous nucleation on MSP. This leads to a great uncertainty in the nucleation rate for mesospheric ice particles. By determining the parameters with the largest impact and comparing different theories we identified a possible range of nucleation rates. These nucleation rates were implemented in the Community Aerosol and Radiation Model for Atmospheres (CARMA). To study the principal effects, CARMA was run in a one-dimensional setup with static background fields and also with dynamically driven fields from the Kühlungsborn Mechanistic Circulation Model (KMCM) for 69°N. The ice particle properties from both runs are compared with observational data from ALOMAR (69°N). We find that while the static background conditions lead to ice particles comparable to those measured by lidar above ALOMAR, the ice particles in the dynamically driven fields do not evolve to detectable populations. To account for the horizontal transport of ice particles, we extended the model to three dimensions and added a tracer algorithm, which enables us to follow the ice particles from their genesis to final evaporation and to analyse the whole life cycle of the ice particles.The modelling studies are completed by a comparison to initial laboratory results for ice nucleation rates on nanometer sized particles under realistic mesopause conditions.

  9. Bite-outs and other depletions of mesospheric electrons

    PubMed Central

    Friedrich, Martin; Rapp, Markus; Plane, John M.C.; Torkar, Klaus M.

    2011-01-01

    The ionised mesosphere is less understood than other parts of the ionosphere because of the challenges of making appropriate measurements in this complex region. We use rocket borne in situ measurements of absolute electron density by the Faraday rotation technique and accompanying DC-probe measurements to study the effect of particles on the D-region charge balance. Several examples of electron bite-outs, their actual depth as well as simultaneous observations of positive ions are presented. For a better understanding of the various dependencies we use the ratio β/αi (attachment rate over ion–ion recombination coefficient), derived from the electron and ion density profiles by applying a simplified ion-chemical scheme, and correlate this term with solar zenith angle and moon brightness. The probable causes are different for day and night; recent in situ measurements support existing hypotheses for daytime cases, but also reveal behaviour at night hitherto not reported in the literature. Within the large range of β/αi values obtained from the analysis of 28 high latitude night flights one finds that the intensity of scattered sunlight after sunset, and even moonlight, apparently can photodetach electrons from meteoric smoke particles (MSP) and molecular anions. The large range of values itself can best be explained by the variability of the MSPs and by occasionally occurring atomic oxygen impacting on the negative ion chemistry in the night-time mesosphere under disturbed conditions. PMID:27570472

  10. Laboratory Studies of Vibrational Relaxation: Important Insights for Mesospheric OH

    NASA Astrophysics Data System (ADS)

    Kalogerakis, Konstantinos S.; Matsiev, Daniel

    2016-04-01

    The hydroxyl radical has a key role in the chemistry and energetics of the Earth's middle atmosphere. A detailed knowledge of the rate constants and relevant pathways for OH(high v) vibrational relaxation by atomic and molecular oxygen and their temperature dependence is absolutely critical for understanding mesospheric OH and extracting reliable chemical heating rates from atmospheric observations. We have developed laser-based experimental approaches to study the complex collisional energy transfer processes involving the OH radical and other relevant atmospheric species. Previous work in our laboratory indicated that the total removal rate constant for OH(v = 9) + O at room temperature is more than one order of magnitude larger than that for removal by O2. Thus, O atoms are expected to significantly influence the intensity and vibrational distribution extracted from the Meinel OH(v) emissions. We will report our most recent laboratory experiments that corroborate the aforementioned result for OH(v = 9) + O and provide important new insights on the mechanistic pathways involved. We will also highlight relevant atmospheric implications, including warranted revisions of current mesospheric OH models. Research supported by SRI International Internal R&D and NSF Aeronomy grant AGS-1441896. Previously supported by NASA Geospace Science grant NNX12AD09G.

  11. The Mesosphere-Lower Thermosphere Turbulence Experiment (MTeX)

    NASA Astrophysics Data System (ADS)

    Collins, R. L.; Barjatya, A.; Lehmacher, G. A.; Fritts, D. C.; Luebken, F.

    2013-12-01

    The Mesosphere-Lower Thermosphere Turbulence Experiment (MTeX), is designed is to contribute to answering one of the key questions in solar-terrestrial science: How do meteorological processes control the impact of solar processes on the Earth's atmosphere? The goal of MTeX is to answer the specific question: What is the contribution of wave-generated turbulence to energetics and mixing in the mesosphere and lower thermosphere (MLT) in the presence of persistent regions of stability and instability? During recent Arctic winters, satellite observations have revealed significant transport of nitrogen oxides (produced by energetic particle precipitation) downward from the thermosphere into the mesosphere, stratosphere and ozone layer. These events have been associated with sudden stratospheric warming events (SSWs) where strong downward transport is observed in the recovery phase of the SSW. However, simulations with current coupled chemistry circulation models indicate that the observed transport cannot be explained by mean flow advection alone. Simulation of the observed transport of nitrogen oxides requires diffusive transport from the thermosphere where the magnitude of the diffusive transport is on order of the mean flow transport. Turbulence is both characterized and measured in terms of energy dissipation rates (used in circulation studies) and eddy diffusion coefficients (used in chemical transport studies). Variability over several orders of magnitude has been reported in turbulence measurements due to both the variety of background conditions present and methods used. High-resolution fluid dynamic simulations continue to raise questions about the physical and statistical assumptions used in determining turbulent characteristics. We propose to make repeated measurements of turbulence in the presence of a Mesospheric Inversion Layer (MIL) in January-February 2015 at Poker Flat Research Range, Chatanika, Alaska. The MIL (~70-90 km) and gravity wave activity in

  12. A semi-empirical model for mesospheric and stratospheric NOy produced by energetic particle precipitation

    NASA Astrophysics Data System (ADS)

    Funke, Bernd; López-Puertas, Manuel; Stiller, Gabriele P.; Versick, Stefan; von Clarmann, Thomas

    2016-07-01

    The MIPAS Fourier transform spectrometer on board Envisat has measured global distributions of the six principal reactive nitrogen (NOy) compounds (HNO3, NO2, NO, N2O5, ClONO2, and HNO4) during 2002-2012. These observations were used previously to detect regular polar winter descent of reactive nitrogen produced by energetic particle precipitation (EPP) down to the lower stratosphere, often called the EPP indirect effect. It has further been shown that the observed fraction of NOy produced by EPP (EPP-NOy) has a nearly linear relationship with the geomagnetic Ap index when taking into account the time lag introduced by transport. Here we exploit these results in a semi-empirical model for computation of EPP-modulated NOy densities and wintertime downward fluxes through stratospheric and mesospheric pressure levels. Since the Ap dependence of EPP-NOy is distorted during episodes of strong descent in Arctic winters associated with elevated stratopause events, a specific parameterization has been developed for these episodes. This model accurately reproduces the observations from MIPAS and is also consistent with estimates from other satellite instruments. Since stratospheric EPP-NOy depositions lead to changes in stratospheric ozone with possible implications for climate, the model presented here can be utilized in climate simulations without the need to incorporate many thermospheric and upper mesospheric processes. By employing historical geomagnetic indices, the model also allows for reconstruction of the EPP indirect effect since 1850. We found secular variations of solar cycle-averaged stratospheric EPP-NOy depositions on the order of 1 GM. In particular, we model a reduction of the EPP-NOy deposition rate during the last 3 decades, related to the coincident decline of geomagnetic activity that corresponds to 1.8 % of the NOy production rate by N2O oxidation. As the decline of the geomagnetic activity level is expected to continue in the coming decades, this is

  13. The Transfer Function Model (TFM) as a Tool for Simulating Gravity Wave Phenomena in the Mesosphere

    NASA Astrophysics Data System (ADS)

    Porter, H.; Mayr, H.; Moore, J.; Wilson, S.; Armaly, A.

    2008-12-01

    The Transfer Function Model (TFM) is semi-analytical and linear, and it is designed to describe the acoustic gravity waves (GW) propagating over the globe and from the ground to 600 km under the influence of vertical temperature variations. Wave interactions with the flow are not accounted for. With an expansion in terms of frequency-dependent spherical harmonics, the time consuming vertical integration of the conservation equations is reduced to computing the transfer function (TF). (The applied lower and upper boundary conditions assure that spurious wave reflections will not occur.) The TF describes the dynamical properties of the medium divorced from the complexities of the temporal and horizontal variations of the excitation source. Given the TF, the atmospheric response to a chosen source is then obtained in short order to simulate the GW propagating through the atmosphere over the globe. In the past, this model has been applied to study auroral processes, which produce distinct wave phenomena such as: (1) standing lamb modes that propagate horizontally in the viscous medium of the thermosphere, (2) waves generated in the auroral oval that experience geometric amplification propagating to the pole where constructive interference generates secondary waves that propagate equatorward, (3) ducted modes propagating through the middle atmosphere that leak back into the thermosphere, and (4) GWs reflected from the Earth's surface that reach the thermosphere in a narrow propagation cone. Well-defined spectral features characterize these wave modes in the TF to provide analytical understanding. We propose the TFM as a tool for simulating GW in the mesosphere and in particular the features observed in Polar Mesospheric Clouds (PMC). With present-day computers, it takes less than one hour to compute the TF, so that there is virtually no practical limitation on the source configurations that can be applied and tested in the lower atmosphere. And there is no limitation on

  14. Mesospheric potassium layer observation by a frequency-tunable resonance scattering lidar system

    NASA Astrophysics Data System (ADS)

    Ejiri, Mitsumu K.; Nakamura, Takuji; Kawahara, Takuya D.; Abo, Makoto; Nishiyama, Takanori; Tsuda, Takuo T.

    The National Institute of Polar Research (NIPR) is leading a six year prioritized project of the Antarctic research observations since 2010. One of the sub-project is entitled "the global environmental change revealed through the Antarctic middle and upper atmosphere". Profiling dynamical parameters such as temperature and wind, as well as minor constituents is the key component of observations in this project, together with a long term observations using existent various instruments in Syowa, the Antarctic (69S, 39E). As a part of the sub-project, Rayleigh/Raman lidar was installed at Syowa Station in January, 2011 and has measured temperature profiles more than 3000 hours by February, 2014. In order to extend the height coverage to include mesosphere and lower thermosphere region, and also to extend the parameters observed, a new resonance scattering lidar system with tunable wavelengths is developed at NIPR in Tokyo (36N, 139E), Japan. The lidar transmitter is based on injection-seeded, pulsed alexandrite laser for 768-788 nm (fundamental wavelengths) and a second-harmonic generation (SHG) unit for 384-394 nm (second harmonic wavelengths). The laser wavelengths are tuned in to the resonance wavelengths by a wavemeter that is well calibrated using a wavelength-stabilized He-Ne laser. The new lidar has capabilities to measure density variations of minor constituents such as atomic iron (Fe, 386 nm), atomic potassium (K, 770 nm), calcium ion (Ca+, 393 nm), and aurorally excited nitrogen ion (N2+, 390-391 nm) and temperature profiles in the mesosphere and lower thermosphere (MLT) region using resonance scatter of K. This unique observation is expected to make important contribution to studies on the atmospheric vertical coupling process and the neutral and charged particle interaction. The resonance scattering lidar system is being developed at NIPR in Tokyo and conducting observations at the mid-latitude. The fundamental laser pulses are transmitted with 120-160 m

  15. Stratosphere/mesosphere coupling during the winter/summer transition at Davis, Antarctica

    NASA Astrophysics Data System (ADS)

    Lübken, Franz-Josef; Höffner, Josef; Viehl, Timo P.; Becker, Erich; Latteck, Ralph; Kaifler, Bernd; Morris, Ray J.

    2015-04-01

    The mobile scanning iron lidar of the Leibniz Institute of Atmospheric Physics in Kühlungsborn (IAP) was in operation at Davis, Antarctica, from December 15, 2010, until December 31, 2012. It measured iron densities, vertical winds, and temperatures in the iron layer, i. e. from approximately 80 to 100 km. The measurement principle is based on probing the Doppler broadened resonance line of iron atoms at 386 nm. The lidar can operate under daylight conditions. Typical values for temperature uncertainty, altitude and time resolution are 3-5 K, 1 km, and 1 hour, respectively. At Davis, the lidar has achieved at total of 2900 hours of temperature measurements which is presumably the largest nearly continuous data set in Antarctica. In this presentation we concentrate on the winter/summer transition in three consecutive years and compare with circulation changes in the stratosphere derived from MERRA (NASA's Modern-Era Retrospective analysis for Research and Applications). We also compare with the northern hemisphere (NH). We find that the thermal structure around the mesopause at Davis is closely coupled to the general circulation in the stratosphere, more precisely to the transition from winter to summer conditions. In contrast to theoretical expectations we occasionally find the mesopause significantly higher and colder(!) compared to the NH. The mesopause altitude changes by several kilometers throughout the summer season, which is significantly different from the summer in the northern hemispheric. Depending on altitude, temperatures can be warmer or colder compared to the NH summer. The Australian Antarctic Division has been operating a 55 MHz VHF radar at Davis since February 2003. We have studied the seasonal variation of polar mesosphere summer echoes (PMSE). PMSE are strong radar echoes related to ice particles and therefore require atmospheric temperatures lower than the frost point temperature. We note that (apart from low temperatures) more ingredients

  16. Energy balance constraints on gravity wave induced eddy diffusion in the mesosphere and lower thermosphere

    NASA Technical Reports Server (NTRS)

    Strobel, D. F.; Apruzese, J. P.; Schoeberl, M. R.

    1985-01-01

    The constraints on turbulence improved by the mesospheric heat budget are reexamined, and the sufficiency of the theoretical evidence to support the hypothesis that the eddy Prandtl number is greater than one in the mesosphere is considered. The mesopause thermal structure is calculated with turbulent diffusion coefficients commonly used in chemical models and deduced from mean zonal wind deceleration. It is shown that extreme mesopause temperatures of less than 100 K are produced by the large net cooling. The results demonstrate the importance of the Prandtl number for mesospheric turbulence.

  17. Exceptionally strong summer-like zonal wind reversal in the upper mesosphere during winter 2015/16

    NASA Astrophysics Data System (ADS)

    Stober, Gunter; Matthias, Vivien; Jacobi, Christoph; Wilhelm, Sven; Höffner, Josef; Chau, Jorge L.

    2017-06-01

    The 2015/16 Northern Hemisphere winter season was marked by peculiarities in the circulation pattern in the high-latitude mesopause region. Wind measurements from the Andenes (69° N, 13° E) meteor radar show westward winds below 84 km and eastward winds above. This wind pattern in the zonal wind was observable between the end of December 2015 and the end of January 2016, i.e., conditions that are typical for the summer were found during winter. Additional meteor radar measurements at midlatitude stations did not show such a zonal wind reversal but indicate, together with the polar latitude stations, a reversal of the horizontal temperature gradient. This is confirmed by global satellite measurements. Therefore, it is plausible that the polar latitude summer-like zonal wind reversal in December-January is in accordance with the reversed horizontal temperature gradient assuming a thermal wind balance between mid- and polar latitudes. The reversed horizontal temperature gradient itself is induced by stationary planetary waves at lower and midlatitudes in the mesosphere, leading to a weakening of the residual circulation above the European sector.

  18. Mesosphere Dynamics with Gravity Wave Forcing. 2; Planetary Waves

    NASA Technical Reports Server (NTRS)

    Mayr, H. G.; Mengel, J. G.; Chan, K. L.; Porter, H. S.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    We present results from a non-linear, 3D, time dependent numerical spectral model (NSM) which extends from the ground up into the thermosphere and incorporates Hines' Doppler Spread Parameterization for small-scale gravity waves (GW). Our focal point is the mesosphere where wave interactions are playing a dominant role. We discuss planetary waves in the present paper and diurnal and semi-diurnal tides in the companion paper. Without external time dependent energy or momentum sources, planetary waves (PWs) are generated in the model for zonal wavenumbers 1 to 4, which have amplitudes in the mesosphere above 50 km as large as 30 m/s and periods between 2 and 50 days. The waves are generated primarily during solstice conditions, which indicates that the baroclinic instability (associated with the GW driven reversal in the latitudinal temperature gradient) is playing an important role. Results from a numerical experiment show that GWs are also involved directly in generating the PWs. For the zonal wavenumber m = 1, the predominant wave periods in summer are around 4 days and in winter between 6 and 10 days. For m = 2, the periods are in summer and close to 2.5 and 3.5 days respectively For m = 3, 4 the predominant wave periods are in both seasons close to two days. The latter waves have the characteristics of Rossby gravity waves with meridional winds at equatorial latitudes. A common feature of the PWs (m = 1 to 4) generated in summer and winter is that their vertical wavelengths throughout the mesosphere are large which indicates that the waves are not propagating freely but are generated throughout the region. Another common feature is that the PWs propagate preferentially westward in summer and eastward in winter, being launched from the westward and eastward zonal winds that prevail respectively in summer and winter altitudes below 80 km. During spring and fall, for m = 1 and 2 eastward propagating long period PWs are generated that are launched from the smaller

  19. Mesospheric imaging Michelson interferometer instrument development and observations

    NASA Astrophysics Data System (ADS)

    Babcock, David D.

    This dissertation demonstrated the capability of the Mesospheric Imaging Michelson Interferometer (MIMI) instrument to passively measure wind velocities from Doppler-shifted atmospheric airglow emissions. The work consisted of two parts, (i) laboratory work focused on the measurement of simulated atmospheric winds with both Doppler-shifted visible and near-IR wavelengths and (ii) the development of a field instrument based on a lab prototype to investigate the potential of measuring Mesospheric winds from the ground. The primary component of the MIMI instrument was a custom built Michelson interferometer which was field widened, chromatically compensated, thermally compensated, and monolithic with no moving parts. The Michelson interferometer, used together with a novel four-point wind retrieval algorithm, provides simultaneous emission rate and wind velocity data over a single integration time. Simultaneously measuring the emission rate over the FOV and measuring wind velocity relative to the observer, of an air parcel containing an emitting chemical species, is a unique feature of the MIMI instrument. Eliminating sequential scanning of the Michelson to measure wind velocities (or being able to take a 'snapshot' of the atmosphere) and provide data on the emission rates and wind velocities, renders the instrument insensitive to scene changes over the integration time, which is an advantage over traditional scanning Michelson interferometers. Spectral lines from visible and near-IR sources were Doppler shifted in a controllable procedure to provide known velocities which were compared to the velocities measured by the interferometer. Wind simulations completed in the visible wavelength region retrieved velocities to within a standard deviation of +/-1ms-1. Wind simulations in the near-IR retrieved wind velocities to within a standard deviation of +/-2ms -1. These standard deviations are acceptable when compared to typical Mesospheric winds of 10 to 100ms-1 and when

  20. Charged aerosols and electrical structure of the polar summer mesopause region

    NASA Technical Reports Server (NTRS)

    Mitchell, John D.; Walter, Deborah J.; Croskey, Charles L.

    1997-01-01

    The results of observations carried out in the framework of two programs, the middle atmosphere electrodynamics campaign and the noctilucent cloud (NLC) campaign, are reported. The measurements performed during overhead NLC and polar mesosphere summer echo (PMSE) conditions revealed a number of aerosol-related layering effects on the region's electrical structure. It was found that both polar components of electrical conductivity can be affected in NLC regions.

  1. Charged aerosols and electrical structure of the polar summer mesopause region

    NASA Technical Reports Server (NTRS)

    Mitchell, John D.; Walter, Deborah J.; Croskey, Charles L.

    1997-01-01

    The results of observations carried out in the framework of two programs, the middle atmosphere electrodynamics campaign and the noctilucent cloud (NLC) campaign, are reported. The measurements performed during overhead NLC and polar mesosphere summer echo (PMSE) conditions revealed a number of aerosol-related layering effects on the region's electrical structure. It was found that both polar components of electrical conductivity can be affected in NLC regions.

  2. Noctilucent clouds observed from the ground: sensitivity to mesospheric parameters and long-term time series

    NASA Astrophysics Data System (ADS)

    Pertsev, Nikolay; Dalin, Peter; Perminov, Vladimir; Romejko, Vitaly; Dubietis, Audrius; Balčiunas, Ričardas; Černis, Kazimieras; Zalcik, Mark

    2014-12-01

    Long-term systematic observations of noctilucent clouds in the regions of Moscow (Russia), Vilnius (Lithuania), and La Ronge (Canada) are considered. Variables, describing the seasonal activity of noctilucent clouds, are discussed. It is shown that there are no statistically significant trends within time intervals of several recent decades. This result is compared to other known findings on trends in mesospheric clouds. Based on the data of the modern ground-based noctilucent cloud observing network in the northern hemisphere and simultaneous satellite data on mesospheric temperature and humidity, we estimate sensitivity of noctilucent clouds to the relative humidity of the upper mesosphere. Such an approach allows us to discuss possible changes of the upper-mesospheric relative humidity, which are consistent with a zero secular trend in noctilucent cloud activity.

  3. Overview of the Temperature Response in the Mesosphere and Lower Thermosphere to Solar Activity

    NASA Technical Reports Server (NTRS)

    Beig, Gufran; Scheer, Juergen; Mlynczak, Martin G.; Keckhut, Philippe

    2008-01-01

    The natural variability in the terrestrial mesosphere needs to be known to correctly quantify global change. The response of the thermal structure to solar activity variations is an important factor. Some of the earlier studies highly overestimated the mesospheric solar response. Modeling of the mesospheric temperature response to solar activity has evolved in recent years, and measurement techniques as well as the amount of data have improved. Recent investigations revealed much smaller solar signatures and in some case no significant solar signal at all. However, not much effort has been made to synthesize the results available so far. This article presents an overview of the energy budget of the mesosphere and lower thermosphere (MLT) and an up-to-date status of solar response in temperature structure based on recently available observational data. An objective evaluation of the data sets is attempted and important factors of uncertainty are discussed.

  4. Mesospheric Odd Nitrogen Enhancements During Relativistic Electron Precipitation Events

    NASA Technical Reports Server (NTRS)

    Aikin, A. C.; Smith, H. J. P.

    1999-01-01

    The behavior of mesospheric odd nitrogen species during and following relativistic and diffuse auroral precipitation events is simulated, Below 75 km nitric oxide is enhanced in proportion to the ion pair production function associated with the electron precipitation and the length of the event. Nitrogen dioxide and nitric acid are also enhanced. At 65 km the percentage of odd nitrogen for N is 0.1%, HNO3 is 1.6%, NO2 is 15%, and NO is 83.3%. Between 75 and 85 km NO is depleted during particle events due to the faster destruction of NO by N relative to the production of NO by N reacting with O2. Recovery of NO depends on transport from the lower thermosphere, where NO is produced in abundant amounts during particle events.

  5. Minor constituents in the upper stratosphere and mesosphere

    NASA Astrophysics Data System (ADS)

    Rusch, David W.; Clancy, R. Todd

    1987-04-01

    The paper highlights the research of the period 1983-1986 on the physical processes responsible for the control of the odd oxyen (Ox) content of the mesosphere. The findings obtained from satellite data sets of LIMS (on ozone, stratospheric water vapor, and NO2), SAMS (on CH4, N2O, and temperature), SBUV (on the UV radiance scattered from the atmosphere), SME, and Spacelab 1 and 'ATMOS' experiments (furnishing data on ozone, stratospheric water vapor, NO2, NO, and temperature) are presented together with the findings based on ground and laboratory observations. Consideration is also given to the results obtained by modeling of the ozone abundances; the solar-induced diurnal variations of ozone; and the transport of NOx, H2O, and CO molecules.

  6. Submillimeter mapping of mesospheric minor species on Venus with ALMA

    NASA Astrophysics Data System (ADS)

    Encrenaz, T.; Moreno, R.; Moullet, A.; Lellouch, E.; Fouchet, T.

    2015-08-01

    Millimeter and submillimeter heterodyne spectroscopy offers the possibility of probing the mesosphere of Venus and monitoring minor species and winds. ALMA presents a unique opportunity to map mesospheric species of Venus. During Cycle 0, we have observed Venus on November 14 and 15, 2011, using the compact configuration of ALMA. The diameter of Venus was 11″ and the illumination factor was about 90%. Maps of CO, SO, SO2 and HDO have been built from transitions recorded in the 335-347 GHz frequency range. A mean mesospheric thermal profile has been inferred from the analysis of the CO transition at the disk center, to be used in support of minor species retrieval. Maps of SO and SO2 abundance show significant local variations over the disk and contrast variations by as much as a factor 4. In the case of SO2, the spatial distribution appears more "patchy", i.e. shows short-scale structures apparently disconnected from day-side and latitudinal variations. For both molecules, significant changes occur over a timescale of one day. From the disk averaged spectrum of SO recorded on November 14 at 346.528 GHz, we find that the best fit is obtained with a cutoff in the SO vertical distribution at 88±2 km and a uniform mixing ratio of 8.0±2.0 ppb above this level. The SO2 map of November 14, derived from the weaker transition at 346.652 GHz, shows a clear maximum in the morning side at low latitudes, which is less visible in the map of November 15. We find that the best fit for SO2 is obtained for a cutoff in the vertical distribution at 88±3 km and a uniform mixing ratio of 12.0±3.5 ppb above this level. The HDO maps retrieved from the 335.395 GHz show some enhancement in the northern hemisphere, but less contrasted variations than for the sulfur species maps, with little change between November 14 and 15. Assuming a typical D/H ratio of 200 times the terrestrial value in the mesosphere of Venus, we find that the disk averaged HDO spectrum is best fitted with a

  7. Tropical behavior of mesospheric ozone as observed by SMM

    NASA Technical Reports Server (NTRS)

    Aikin, A. C.; Kendig, D. J.

    1992-01-01

    The seasonal behavior of low latitude mesospheric ozone, as observed by the SMM satellite solar occultation experiment, is detailed for the 1985-1989 period. Annual as well as semi-annual waves are observed in the 50-70 km altitude region. In the latitude range of +/- 30 deg the ozone phase and amplitude are functions of temperature and seasonal changes in solar flux. Temperature is the controlling factor for the equatorial region and seasonal changes in solar flux become more dominant at latitudes outside the equatorial zone (greater than +/- 15 deg). There is a hemispheric asymmetry in the ozone annual wave in the 20-30 deg region, with Northern Hemispheric ozone having a larger amplitude than Southern Hemispheric ozone.

  8. Rapid space/time variations in mesospheric ozone

    NASA Technical Reports Server (NTRS)

    Buhl, D.; Brown, L. W.; Lovas, F. J.

    1978-01-01

    A 5 meter telescope was used to observe variations in the narrow emission line which is present in the nightime emission spectrum of ozone. The line was measured for several nights on two different transitions of the ozone molecule at 110.8 GHz and 142.2 GHz. Individual spectra with a time resolution of 5 minutes were taken. The narrow emission line showed considerable variation in intensity indicating that the ozone layer from which its arises has a rather detailed structure. Analysis of the line profile shows that the emission is coming from an ozone layer in the 55-75 km region of the mesosphere. This layer has a column density of 2 x 10 to the 16th power molecules/sq cm in a vertical path through the region.

  9. Passive remote sensing of stratospheric and mesospheric winds

    NASA Technical Reports Server (NTRS)

    Mccleese, Daniel J.; Margolis, Jack S.

    1985-01-01

    A passive infrared sensor is described for remote sounding of the wind field in the stratosphere and mesosphere from near Earth orbital spacecraft. The instrument uses gas correlation spectroscopy together with electro-optic phase modulation techniques to measure winds in the 20- to 120-km altitude range globally, both in the day and at night, and with a vertical resolution of better than the atmospheric scale height. Measurement of temperature and the amounts of key atmospheric species may also be made simultaneously and in coincident fields of view with the wind observations. The sensor is currently being developed at the Jet Propulsion Laboratory as a candidate for the upcoming NASA Earth Observation System.

  10. Long-term changes in the mesosphere calculated by a two-dimensional model

    NASA Astrophysics Data System (ADS)

    Gruzdev, Aleksandr N.; Brasseur, Guy P.

    2005-02-01

    We have used the interactive two-dimensional model SOCRATES to investigate the thermal and the chemical response of the mesosphere to the changes in greenhouse gas concentrations observed in the past 50 years (CO2, CH4, water vapor, N2O, CFCs), and to specified changes in gravity wave drag and diffusion in the upper mesosphere. When considering the observed increase in the abundances of greenhouse gases for the past 50 years, a cooling of 3-7 K is calculated in the mesopause region together with a cooling of 4-6 K in the middle mesosphere. Changes in the meridional circulation of the mesosphere damp the pure radiative thermal effect of the greenhouse gases. The largest cooling in the winter upper mesosphere-mesopause region occurs when the observed increase in concentrations of greenhouse gases and the strengthening of the gravity wave drag and diffusion are considered simultaneously. Depending on the adopted strengthening of the gravity wave drag and diffusion, a cooling varying from typically 6-10 K to 10-20 K over the past 50 years is predicted in the extratropical upper mesosphere during wintertime. In summer, however, consistently with observations, the thermal response calculated by the model is insignificant in the vicinity of the mesopause. Although the calculated cooling of the winter mesopause is still less than suggested by some observations, these results lead to the conclusion that the increase in the abundances of greenhouse gases alone may not entirely explain the observed temperature trends in the mesosphere. Long-term changes in the dynamics of the middle atmosphere (and the troposphere), including changes in gravity wave activity may have contributed significantly to the observed long-term changes in thermal structure and chemical composition of the mesosphere.

  11. Variabilities of low latitude mesospheric and E region echoes: linked to common sources?

    NASA Astrophysics Data System (ADS)

    Dharmalingam, Selvaraj; Patra, Amit; Sathishkumar, Sundararaman; Narayana Rao, D.

    2016-07-01

    Variability in dynamics of the mesospheric and E region echoes have been studied in isolation. Both echoing phenomena are directly or indirectly coupled with each other through neutral dynamics. This is especially so for the low-latitudes outside the equatorial electrojet belt, where E region plasma irregularities causing radar echoes are governed by neutral dynamics, such as tides and gravity waves. Although these regions are close to each other, no effort has been made yet to understand the dynamical coupling processes manifesting the observed variabilities in the two echoing phenomena. To investigate linkage between the two phenomena, if any, we conducted systematic observations of low latitude mesospheric and E region echoes during 2011-2012 using the Gadanki MST radar and used these in conjunction with SABER temperature, MF radar wind, and sporadic E observations. Both echoes are found to occur in the height regions where temperature observations show negative gradients. Mesospheric echoes are collocated with temperature gradient associated with mesospheric temperature inversion while the E region echoes are collocated with negative temperature gradient close to the mesopause. Observations have revealed a common signature of semi-annual variations in the occurrence of both mesospheric and ionospheric E-region - occurrences peak in the equinoxes. The E region echoes have an additional peak occurring in the summer and this occurrence is well correlated with the enhancement in the diurnal tidal amplitude. We surmise that the enhancement in the diurnal tidal amplitude is linked with non-migrating tide of tropospheric weather phenomena in summer. Intriguingly, mesospheric echoing layers display descending pattern quite similar to the E region echoes and sporadic E layer, which have been used to invoke tidal dynamics in manifesting similar morphology in both mesospheric and E region echoes. These results will be presented and the role of tidal dynamics on the

  12. Stratospheric and Mesospheric Trace Gas Studies Using Ground-Based mm-Wave Receivers

    NASA Technical Reports Server (NTRS)

    daZafra, Robert L.

    1997-01-01

    The goal of the proposed work was to understand the latitude structure of nitric oxide in the mesosphere and lower thermosphere. The problem was portrayed by a clear difference between predictions of the nitric oxide distribution from chemical/dynamical models and data from observations made by the Solar Mesosphere Explorer (SMEE) in the early to mid eighties. The data exhibits a flat latitude structure of NO, the models tend to produce at equatorial maximum.

  13. High-Altitude Data Assimilation System Experiments for the Northern Summer Mesosphere Season of 2007

    DTIC Science & Technology

    2009-01-01

    variations in PMC frequency measured from the aeronomy of ice in the mesosphere (AIM) satellite. Synoptic maps of these diagnostic saturation ratios...compare well with seasonal variations in PM Cfrequency measured from the aeronomy of ice in themesosphere (AIM )satellite. Synoptic maps of these...data, such as provided by the aeronomy of ice in the mesosphere (AIM) satellite (Russell et al., 2008), are particularly valuable, either for direct

  14. Mesospheric water vapor measurements from Penn State - Monthly mean observations (1984-1987)

    NASA Technical Reports Server (NTRS)

    Bevilacqua, Richard M.; Olivero, John J.; Croskey, Charles L.

    1989-01-01

    Mesospheric water vapor measurements obtained by ground-based microwave spectroscopy between November 1984 and July 1987 are examined. Monthly mean water vapor profiles are used to establish annual and interannual variability. The results suggest that the seasonal variation of upper mesospheric water vapor is dominated by an annual component with low mixing ratios in winter and high mixing ratios in summer. The results are compared with those reported by Bevilacqua et al. (1987).

  15. A review of mesospheric and lower thermosphere models

    NASA Astrophysics Data System (ADS)

    Portnyagin, Yuri

    2006-01-01

    The empirical mesosphere/lower thermosphere (MLT) models, in particular Fleming et al. [Fleming, E.L., Chandra, S., Schoeberl, M.R., Barnett, J.J. Monthly mean global climatology of temperature, wind, geopotential height and pressure for 0-120 km. NASA Technical Memorandum 100697, 1988; Fleming, E.L., Chandra, S., Barnett, J.J., Corney, M. Zonal mean temperature, pressure, zonal wind and geopotential height as function of latitude. Adv. Space Res., 10 (12), 11-59, 1990.], HWM-93 [Hedin, A.E., Fleming, E.L., Manson, A.H., Schmidlin, F.J., Avery, S.K., Clark, R.R., Franke, S.J., Fraser, G.J., Tsuda, T., Vial, F., Vincent, R.A. Empirical wind model for the middle and lower atmosphere. J. Atmos.Terr. Phys., 58, 1421-1447, 1996] and GEWM [Portnyagin, Yu.I, Solovjova, T., Merzlyakov, E., et al., Mesosphere/lower thermosphere prevailing wind model. Adv. Space Res., 34, 1755-1762, 2004] models, are compared. The main reasons of the differences between the models are discussed. These reasons are mainly connected with the differences between the used ground- and space-based datasets, including the systematic biases between the ground-based and space-based measurements, and with the different methods of the data assimilation. The effects of year-to-year wind variations and the longitudinal prevailing wind variability, as well as the effects of non-migrating tides in construction of the climatic empirical models is not so strong. The recommendation to construct a new and updated CIRA wind model for the MLT region has been followed.

  16. Trends and solar cycle effects in mesospheric ice clouds

    NASA Astrophysics Data System (ADS)

    Lübken, Franz-Josef; Berger, Uwe; Fiedler, Jens; Baumgarten, Gerd; Gerding, Michael

    Lidar observations of mesospheric ice layers (noctilucent clouds, NLC) are now available since 12 years which allows to study solar cycle effects on NLC parameters such as altitudes, bright-ness, and occurrence rates. We present observations from our lidar stations in Kuehlungsborn (54N) and ALOMAR (69N). Different from general expectations the mean layer characteris-tics at ALOMAR do not show a persistent anti-correlation with solar cycle. Although a nice anti-correlation of Ly-alpha and occurrence rates is detected in the first half of the solar cycle, occurrence rates decreased with decreasing solar activity thereafter. Interestingly, in summer 2009 record high NLC parameters were detected as expected in solar minimum conditions. The morphology of NLC suggests that other processes except solar radiation may affect NLC. We have recently applied our LIMA model to study in detail the solar cycle effects on tempera-tures and water vapor concentration the middle atmosphere and its subsequent influence on mesospheric ice clouds. Furthermore, lower atmosphere effects are implicitly included because LIMA nudges to the conditions in the troposphere and lower stratosphere. We compare LIMA results regarding solar cycle effects on temperatures and ice layers with observations at ALO-MAR as well as satellite borne measurements. We will also present LIMA results regarding the latitude variation of solar cycle and trends, including a comparison of northern and southern hemisphere. We have adapted the observation conditions from SBUV (wavelength and scatter-ing angle) in LIMA for a detailed comparison with long term observations of ice clouds from satellites.

  17. Potential causes for the extraordinarily cold and strong Arctic polar vortex in winter 2015/16

    NASA Astrophysics Data System (ADS)

    Matthias, Vivien; Dörnbrack, Andreas; Stober, Gunter

    2017-04-01

    The Arctic polar vortex was extraordinarily cold and strong at the beginning of the winter 2015/16, strong and displaced in mid-winter and broke down in early March 2016. We investigate the characteristics of the polar vortex using global reanalysis data, satellite observations, and mesospheric radar wind measurements over northern Scandinavia. The results are related to previous winters of the last decades. The focus of this study is on finding the causes for the extraordinary behavior of the Arctic polar vortex in the early and late winter 2015/16. In early winter we found a correlation between the planetary wave (PW) activity and the strength and temperature of the Arctic polar vortex in the stratosphere and mesosphere. In Nov/Dec 2015, a reduced PW generation in the troposphere and a stronger PW filtering in the troposphere and stratosphere, caused by stronger zonal winds in mid-latitudes, resulted in a stronger polar vortex. Another peculiarity of the winter 2015/16 occurred after the unusually early breakdown of the Arctic polar vortex. Typically the zonal mean zonal wind remains easterly until autumn. However, the zonal wind in the mesosphere between 50 and 80 km became westerly again after the "final warming" for over 30 days. During this phenomenon there is no sign of planetary wave activity why other possible causes will be discussed.

  18. Radar studies of turbulence and lidar studies of the nickel layer in the arctic mesosphere

    NASA Astrophysics Data System (ADS)

    Li, Jintai

    This thesis presents studies of the Arctic middle atmosphere using Incoherent Scatter Radar (ISR) and resonance lidar at Poker Flat Research Range (PFRR), Chatanika, Alaska. The Poker Flat Incoherent Scatter Radar (PFISR) provides measurements of mesospheric turbulence and the resonance lidar provides measurements of mesospheric nickel layer. We develop retrieval and analysis techniques to determine the characteristics of the turbulence and the nickel layer. We present measurements of mesospheric turbulence with PFISR on 23 April 2008 and 18 February 2013. We characterize mesospheric turbulence in terms of the energy dissipation rate as a function of altitude and time on these days. We present an extensive analysis of the radar measurements to show that the use of high quality PFISR data and an accurate characterization of the geophysical conditions are essential to achieve accurate turbulent measurements. We find that the retrieved values of the energy dissipation rate vary significantly based on how the data is selected. We present measurements of mesospheric nickel layer with resonance lidar on the night of 27-28 November 2012 and 20-21 December 2012. We characterize the mesospheric nickel layer in terms of the nickel concentration as a function of altitude on these days. We find that our nickel concentrations are significantly higher than expected from studies of meteors. We present an extensive analysis of the lidar measurements to show that these measurements of unexpectedly high values of the nickel concentrations are accurate and not biased by the lidar measurements.

  19. Temporal evolution of radar echoes associated with mesospheric dust clouds after turn-on of radio wave heating

    NASA Astrophysics Data System (ADS)

    Mahmoudian, A.; Scales, W. A.

    2012-03-01

    The initial perturbation of polar mesospheric summer echoes PMSEs during radio wave heating provides significant diagnostic information about the charged dust layer associated with the irregularity source region. Comparison between the results of computational models and the observation data can be used as a tool to estimate charged dust layer parameters. An analytical model is developed and compared to a more accurate computational model as a reference to investigate the possibilities for diagnostic information as well as insight into the physical processes after heater turn-on. During radio wave heating of the mesosphere, which modifies the background electron temperature, various temporal evolution characteristics of irregularity amplitude may be observed which depend on the background plasma parameters and the characteristics of the dust layer. Turn-on overshoot due to the dominant electron charging process and turn-on undershoot resulting from the dominant ambipolar diffusion process, that can occur simultaneously at different radar frequencies, have been studied. The maximum and minimum of the electron density irregularity amplitude and the time at which this amplitude has been achieved as well as the decay time of irregularity amplitude after the maximum amplitude are unique observables that can shed light on the physical processes after the turn-on of the pump heating and to diagnose the charged dust layer. The agreement between the computational and analytical results are good and indicate the simplified analytical model may be used to provide considerable insight into the heating process and serve as the basis for a diagnostic model after heater turn-on. Moreover, the work proposes that conducting PMSE active experiments in the HF and VHF band simultaneously may allow estimation of the dust density altitude profile, dust charge state variation during pump heating, and ratio of electron temperature enhancement in the irregularity source region.

  20. CONDENSED MATTER: STRUCTURE, THERMAL AND MECHANICAL PROPERTIES: Polarized spin transport in mesoscopic quantum rings with electron-phonon and Rashba spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Liu, Ping; Xiong, Shi-Jie

    2009-12-01

    The influence of electron-phonon (EP) scattering on spin polarization of current output from a mesoscopic ring with Rashba spin-orbit (SO) interaction is numerically investigated. There are three leads connecting to the ring at different positions; unpolarized current is injected to one of them, and the other two are output channels with different bias voltages. The spin polarization of current in the outgoing leads shows oscillations as a function of EP coupling strength owing to the quantum interference of EP states in the ring region. As temperature increases, the oscillations are evidently suppressed, implying decoherence of the EP states. The simulation shows that the magnitude of polarized current is sensitive to the location of the lead. The polarized current depends on the connecting position of the lead in a complicated way due to the spin-sensitive quantum interference effects caused by different phases accumulated by transmitting electrons with opposite spin states along different paths.

  1. Wave-coupling from the troposphere to the mesosphere and thermosphere observed by the Optical Mesosphere Thermosphere Imagers (OMTIs)

    NASA Astrophysics Data System (ADS)

    Shiokawa, Kazuo; Otsuka, Yuichi; Takeo, Daiki; Fujinami, Hatsuki

    2016-07-01

    The airglow emissions from the mesopause region and the thermosphere are very useful to monitor dynamical variations of the neutral and plasma atmosphere in the upper atmosphere. The Optical Mesosphere Thermosphere Imagers (OMTIs) measure two-dimensional pattern, Doppler wind, and temperature through airglow emissions from oxygen (wavelength: 557.7 nm) and OH (near infrared band) in the mesopause region (80-100 km) and from oxygen (630.0 nm) in the thermosphere/ionosphere (200-300 km) at various locations in the world. Station information and quick look plots are available at http://stdb2.stelab.nagoya-u.ac.jp/omti/. In this presentation we show recent observations by OMTIs for the vertical coupling of atmospheric gravity waves from the troposphere to the mesopause region and to the thermosphere/ionosphere.

  2. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Spin Polarizations of Electron with Rashba Couplings in T-Shaped Devices: A Finite Element Approach

    NASA Astrophysics Data System (ADS)

    Zhu, Song; Liu, Hui-Ping; Yi, Lin

    2010-09-01

    A generalized finite element formulation is proposed for the study of the spin-dependent ballistic transport of electron through the two-dimensional quantum structures with Rashba spin-orbit interactions (SOI). The transmission coefficient, conductance, the total and local polarization are numerically calculated and discussed as the Rashba coefficient, the geometric sizes, and incident energy are changed in the T-shaped devices. Some interesting features are found in the proper parameter regime. The polarization has an enhancement as the Rashba coefficient becomes stronger. The polarization valley is rigid in the regime of the conductance plateaus since the local interference among the polarized multi-wave modes. The Rashba interactions coupling to geometry in sizes could form the structure-induced Fano-Rashba resonance. In the wider stub, the localized spin lattice of electron could be produced. The conductance plateaus correspond to weak polarizations. Strong polarizations appear when the stub sizes, incident energy, and the Rashba coupling coefficient are matched. The resonances are formed in a wide Fermi energy segment easily.

  3. Observations of the global structure of the stratosphere and mesosphere with sounding rockets and with remote sensing techniques from satellites

    NASA Technical Reports Server (NTRS)

    Heath, D. F.; Hilsenrath, E.; Krueger, A. J.; Nordberg, W.; Prabhakara, C.; Theon, J. S.

    1972-01-01

    Brief descriptions are given of the techniques involved in determining the global structure of the mesosphere and stratosphere based on sounding rocket observations and satellite remotely sensed measurements.

  4. SCIAMACHY’s View of the Polar Atmosphere

    USGS Publications Warehouse

    Gottwald, M.; Krieg, E.; von Savigny, C.; Noël, S.; Reichl, A.; Bovensmann, H.; Burrows, J.P.

    2007-01-01

    The instrument SCIAMACHY onboard the European ENVISAT mission provides unique capabilities for deriving atmospheric geophysical parameters. Since its launch in early 2002 it has operated successfully in orbit. Due to ENVISAT’s high inclination orbit the polar regions are monitored continuously. We report here results about the status of the polar atmosphere in the past 5 years with special emphasis on the southern hemisphere. This part of the atmosphere is considered to be highly sensitive to anthropogenic impacts on the Earth system and thus to climate change. The acquired data permit retrieving information on the Earth’s atmosphere from troposphere up to the mesosphere

  5. Mesospheric temperature soundings with the new, daylight-capable IAP RMR lidar

    NASA Astrophysics Data System (ADS)

    Gerding, Michael; Kopp, Maren; Höffner, Josef; Baumgarten, Kathrin; Lübken, Franz-Josef

    2016-08-01

    Temperature measurements by lidar are an important tool for the understanding of the mean state of the atmosphere as well as the propagation of gravity waves and thermal tides. Though, mesospheric lidar soundings are often limited to nighttime conditions (e.g., solar zenith angle > 96°) due to the low signal-to-noise ratio during the day. By this, examination of long-period gravity waves and tides is inhibited, as well as soundings in summer at polar latitudes. We developed a new daylight-capable Rayleigh-Mie-Raman (RMR) lidar at our site in Kühlungsborn, Germany (54° N, 12° E), that is in routine operation since 2010 for temperature soundings up to 90 km or ˜ 75 km (night or day) and soundings of noctilucent clouds. Here we describe the setup of the system with special emphasis on the daylight suppression methods like spatial and spectral filtering. The small bandwidth of the Fabry-Pérot etalons for spectral filtering of the received signal induces an altitude-dependent transmission of the detector. As a result, the signal is no longer proportional to the air density and the hydrostatic integration of the profile results in systematic temperature errors of up to 4 K. We demonstrate a correction method and the validity of correction by comparison with data obtained by our co-located, nighttime-only RMR lidar where no etalon is installed. As a further example a time series of temperature profiles between 20 and 80 km is presented for day and night of 9-10 March 2014. Together with the other data of March 2014 these profiles are used to calculate tidal amplitudes. It is found that tidal amplitudes vary between ˜ 1 and 5 K depending on altitude.

  6. High-resolution observations and modeling of turbulence sources, structures, and intensities in the upper mesosphere

    NASA Astrophysics Data System (ADS)

    Fritts, David C.; Wang, Ling; Baumgarten, Gerd; Miller, Amber D.; Geller, Marvin A.; Jones, Glenn; Limon, Michele; Chapman, Daniel; Didier, Joy; Kjellstrand, Carl B.; Araujo, Derek; Hillbrand, Seth; Korotkov, Andrei; Tucker, Gregory; Vinokurov, Jerry

    2017-09-01

    New capabilities for imaging small-scale instabilities and turbulence and for modeling gravity wave (GW), instability, and turbulence dynamics at high Reynolds numbers are employed to identify the major instabilities and quantify turbulence intensities near the summer mesopause. High-resolution imaging of polar mesospheric clouds (PMCs) reveal a range of instability dynamics and turbulence sources that have their roots in multi-scale GW dynamics at larger spatial scales. Direct numerical simulations (DNS) of these dynamics exhibit a range of instability types that closely resemble instabilities and turbulence seen in PMC imaging and by ground-based and in-situ instruments at all times and altitudes. The DNS also exhibit the development of ;sheet-and-layer; (S&L) structures in the horizontal wind and thermal stability fields that resemble observed flows near the mesopause and at lower altitudes. Both observations and modeling suggest major roles for GW breaking, Kelvin-Helmholtz instabilities (KHI), and intrusions in turbulence generation and energy dissipation. Of these, larger-scale GW breaking and KHI play the major roles in energetic flows leading to strong turbulence. GW propagation and breaking can span several S&L features and induce KHI ranging from GW to turbulence scales. Intrusions make comparable contributions to turbulence generation as instabilities become weaker and more intermittent. Turbulence intensities are highly variable in the vertical and typically span 3 or more decades. DNS results that closely resemble observed flows suggest a range of mechanical energy dissipation rates of ε 10-3-10 W kg-1 that is consistent with the range of in-situ measurements at 80-90 km in summer.

  7. Infrared radiation in the mesosphere and lower thermosphere: energetic effects and coupling with lower atmosphere

    NASA Astrophysics Data System (ADS)

    Feofilov, Artem; Kutepov, Alexander; Rezac, Ladislav

    2013-04-01

    The translational degrees of freedom of atmospheric molecular and atomic gaseous compounds represent the heat reservoir. This reservoir obtains or loses energy due to a number of sources and sinks, among them heating and cooling related to various types of mass motions, redistribution of energy released in the course of various photochemical reactions (the translational energy, the chemical energy and the nascent electronic, vibration and rotational energy of the reaction products), and absorption and emission of the infrared (IR) radiation. In the latter case, one deals with interaction between matter and the IR radiative field, which, for the case of the mesosphere/lower thermosphere (MLT), includes the atmospheric radiation formed in these layers, the upwelling radiation from the ground and lower atmosphere, and, during daytime, the IR solar radiation. In this talk, we address the energetic effects of IR radiation in the MLT and its radiative coupling with lower atmosphere by analyzing the interaction between IR radiation and matter. In the MLT, this interaction is strongly affected by the situation when vibrational (and in its upper part also rotational) excitation of the molecules does not obey Boltzmann's law with the local kinetic temperature. As a result, the IR radiation emitted in these layers does not reflect the thermal state of matter. This situation is referred to as the breakdown of local thermodynamic equilibrium (LTE) for the vibrational (or rotational-vibrational) degrees of freedom. Detailed treatment of non-LTE plays a crucial role for estimating thermal effects of the IR radiation as well as for the diagnostics of space-based IR observations. We discuss the peculiarities of the non-LTE radiation formation in the IR bands of CO2, O3, and H2O molecules, estimate radiative cooling/heating rates for typical atmospheric scenarios, and analyze sensitivity of the MLT radiative energy balance to various mechanisms of populating/depopulating molecular

  8. Coordinated investigation of midlatitude upper mesospheric temperature inversion layers and the associated gravity wave forcing by Na lidar and Advanced Mesospheric Temperature Mapper in Logan, Utah

    NASA Astrophysics Data System (ADS)

    Yuan, Tao; Pautet, P.-D.; Zhao, Y.; Cai, X.; Criddle, N. R.; Taylor, M. J.; Pendleton, W. R.

    2014-04-01

    Mesospheric inversion layers (MIL) are well studied in the literature but their relationship to the dynamic feature associated with the breaking of atmospheric waves in the mesosphere/lower thermosphere (MLT) region are not well understood. Two strong MIL events (ΔT ~30 K) were observed above 90 km during a 6 day full diurnal cycle Na lidar campaign conducted from 6 August to 13 August Logan, Utah (42°N, 112°W). Colocated Advanced Mesospheric Temperature Mapper observations provided key information on concurrent gravity wave (GW) events and their characteristics during the nighttime observations. The study found both MILs were well correlated with the development and presence of an unstable region ~2 km above the MIL peak altitudes and a highly stable region below, implicating the strengthening of MIL is likely due to the increase of downward heat flux by the enhanced saturation of gravity wave, when it propagates through a highly stable layer. Each MIL event also exhibited distinct features: one showed a downward progression most likely due to tidal-GW interaction, while the peak height of the other event remained constant. During further investigation of atmospheric stability surrounding the MIL structure, lidar measurements indicate a sharp enhancement of the convective stability below the peak altitude of each MIL. We postulate that the sources of these stable layers were different; one was potentially triggered by concurrent large tidal wave activity and the other during the passage of a strong mesospheric bore.

  9. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Spin-Polarized Transport through a Quantum Dot Coupled to Ferromagnetic Leads and a Mesoscopic Ring

    NASA Astrophysics Data System (ADS)

    Huang, Rui; Wu, Shao-Quan

    2010-02-01

    Using an equation of motion technique, we investigate the spin-polarized transport through a quantum dot coupled to ferromagnetic leads and a mesoscopic ring by the Anderson Hamiltonian. We analyze the transmission probability of this system in both the equilibrium and nonequilibrium cases, and our results reveal that the transport properties show some noticeable characteristics depending upon the spin-polarized strength p, the magnetic flux Φ and the number of lattice sites NR in the mesoscopic ring. These effects might have some potential applications in spintronics.

  10. Rapid Variability of Water Vapor Abundance in the Venus Mesosphere

    NASA Astrophysics Data System (ADS)

    Gurwell, Mark A.; Melnick, G. J.; Tolls, V.; Bergin, E. A.; Patten, B. M.

    2006-09-01

    We present the first detections of the water vapor ground-state rotational transition (at 556.9 GHz) and the 13CO(5-4) rotational transition (at 550.9 GHz) from the atmosphere of Venus, obtained with the Submillimeter Wave Astronomy Satellite (SWAS). These submillimeter transitions originate primarily from the 70-100 km altitude range, within the Venus mesosphere. Observations were obtained in December 2002, and January, March, and July 2004, coarsely sampling one Venus diurnal period as seen from Earth. Complementary observations of the 12CO(2-1) rotational transition (at 230.5 GHz) were obtained concurrently with the Submillimeter Array (SMA) to help constrain global atmospheric parameters. The water vapor absorption line depth shows large variability among the four observing periods, with strong detections of the water line in December 2002 and July 2004, and no detections in January and March of 2004. Using a multi-transition inversion algorithm (combining temperature, carbon monoxide, and water profile retrieval under some constraints), we retrieved or found upper limits for the globally averaged mesospheric water vapor abundance for each period, finding variability over at least two orders of magnitude. The results are consistent with both temporal and diurnal variability, but with short-term fluctuations clearly dominating. The observations from December 2002 detected very rapid changes in water vapor abundance. Over five days, a deep ground-state water absorption feature consistent with a water abundance of 4.5±1.5 ppm suddenly gave way to a significantly shallower absorption, implying a decrease in the water abundance by a factor of nearly 50 in less than 48 hours. In 2004 similar changes in water vapor abundance are seen between the March and July SWAS observing periods, but variability on timescales of less than a week was not detected. M.A.G. gratefully acknowledges support from NASA contract NAG5-7946. G.J.M., V.T., E.A.B, and B.M.P. were supported by

  11. Analysis of a temperature inversion event in the lower mesosphere

    NASA Astrophysics Data System (ADS)

    Liu, Han-Li; Meriwether, John W.

    2004-01-01

    Rayleigh lidar measurements of stratospheric and lower mesospheric temperatures obtained at the Urbana Atmospheric Observatory (40.1°N, 88.1°W) on 17/18 November 1997 revealed large temperature inversions at altitudes between 55 to 65 km. Prior to and during a large increase (by up to about 50K) in the amplitude of the mesosphere inversion layer (MIL), a clear and persistent vertical wave structure between 30 and 65 km was observed. The wave has a vertical wavelength of about 12 km and an apparent period of about 12 hours. However, the intrinsic characteristics of the wave are uncertain due to the lack of information regarding the background wind profile and the relative direction of the wave propagation vector with respect to the background wind vector. Two different cases, corresponding to small and large background wind speeds projected onto the horizontal direction of wave propagation, are studied numerically to represent two scenarios with different intrinsic wave characteristics devised to explain the development of the MIL event observed. When the projected background wind is small, the wave is likely to be an inertial-gravity wave. It is shown that the breaking of such a wave does not produce the large heating rate observed. However, the numerical modeling shows that such an inertial-gravity wave can modulate the stability of a separate internal gravity wave, and the breaking of this internal gravity wave produces a heating rate similar to the observed rate. When the projected background wind is large, however, the observed wave could be an internal gravity wave with a large intrinsic phase speed. The analysis shows that the breaking of this wave can generate a large heating rate and a MIL that is similar to the observed event. We close with a discussion of the observational implications of these two scenarios. Possible wave sources are also discussed, and it appears that the observed MIL event might be related to a developing frontal system in the

  12. MTeX: The Mesosphere-Lower Thermosphere Turbulence Experiment

    NASA Astrophysics Data System (ADS)

    Collins, R. L.; Triplett, C. C.; Barjatya, A.; Lehmacher, G. A.; Fritts, D. C.; Luebken, F. J.; Strelnikov, B.; Nicolls, M. J.

    2015-12-01

    The Mesosphere-Lower Thermosphere Turbulence Experiment (MTeX) is a rocket-based experiment that was conducted on the night of the 25-26 January 2015 at Poker Flat Research Range (PFRR), Chatanika, Alaska (65°N, 147°W). The experiment required two key elements: the ability to measure turbulence in well-defined meteorological conditions and the ability to measure fluctuations in the atmosphere at sub-meter scales. Modern lidar (or laser radar) systems provided the first element. Rocket-borne ionization gauges and ionization probes provided the second element. We used the established rocket launching and lidar facilities at PFRR to study this turbulence. The specific weather condition we required to frame our turbulence measurement was a Mesospheric Inversion Layer. MILs are a signature of large-scale planetary wave breaking in the upper atmosphere, where a region with a temperature inversion lies below a region with an adiabatic lapse rate. The region with the inversion allows small-scale waves to become unstable, break, and generate turbulence. The region with the adiabatic lapse rate is indicative of a well-mixed layer and the presence of turbulence. The Rayleigh lidar observations began at 18:37 25 January local time. By 20:30 we had acquired sufficient lidar signal to detect a MIL between 80-85 km. The first MTeX rocket was launched at 00:13 and the second one at 00:46. The lidar temperature soundings show that the atmosphere was disturbed with temperatures in the stratosphere being cooler than expected from climatology with no clear stratopause. Our preliminary analysis of the rocket measurements shows spectral characteristics typical of layers of strong turbulence. Measurements were made both on the upleg and downleg of each rocket flight. In this presentation we present the technical details of the rocket flight, key data from the flight, and show how that data from different instruments is combined to characterize the waves and turbulence present during

  13. Consequences of Recent Southern Hemisphere Winter Variability on Polar Mesospheric Clouds

    DTIC Science & Technology

    2011-01-01

    to the latitude region where ground based observers see these clouds as noctilucent clouds ( NLCs ). We also only considered clouds, which occurred at...cloudy (colder) and clear (warmer) airmasses. However, even ground based data (Hoffner et al., 2003) have recorded NLCs at temperatures as warm as 157 K...Baumgarten, G., Berger, U., Hoffmann, P., Kaifler, N., Lubken, F.-J., 2011. NLC and the background atmosphere above ALOMAR. Atmospheric Chemistry

  14. First observations of polar mesosphere summer echoes by SuperDARN Zhongshan radar

    NASA Astrophysics Data System (ADS)

    Liu, E. X.; Hu, H. Q.; Hosokawa, K.; Liu, R. Y.; Wu, Z. S.; Xing, Z. Y.

    2013-11-01

    We report the first observations of PMSE by SuperDARN Zhongshan radar in Antarctica and present a statistical analysis of PMSE from 2010 to 2012. The seasonal variations of occurrence are consistent with those before, with an obvious enhancement at the beginning of summer and a maximum several days after summer solstice. The special features of diurnal variations were observed because of high geomagnetic latitude of Zhongshan Station, which is that the maximum is near local midnight and the secondary maximum appears 1-2 h after the local noon. The results proved that the auroral particle precipitation plays a fairly important role in the PMSE occurrence.

  15. On the Possible Anticorrelation of Polar Mesospheric (Noctilucent) Clouds and Aurorae.

    DTIC Science & Technology

    1986-08-01

    that sudden aurorally induced heating may generate these waves. Testud (1970) made some numerical computations which show that heating can create...Nitrogen from 50-120 km, II. D-region ion chemistry and the winter anomaly. J. Geophys. Res., 87, 7206. Testud , J., 1970: Gravity waves generated during

  16. Polar Mesospheric Cloud Mass and the Ice Budget: 2. Application to Satellite Data Sets

    DTIC Science & Technology

    2007-04-20

    now indicate that the environment over Antarctica is less conducive to PMC formation than over the Arctic [Thomas et al., 1991; Bailey et al., 2005...satellites operating at vari- ous times since November 1978 [DeLand et al., 2006]. SBUV PMC albedos are reported at 252.0 nm and the ice mass from one northern...2007]. Such high frequencies can lead to a negative bias in SBUV cloud frequencies and albedos because there are not enough clear air data to reliably

  17. Statistical analysis of solar wind stream interface induced temperature effects on the upper mesosphere and lower thermosphere over SANAE IV, Antarctica

    NASA Astrophysics Data System (ADS)

    Ogunjobi, Olakunle; Sivakumar, Venkataraman; William; Sivla, T.

    Using superposed epoch techniques, the TIMED (Thermosphere Ionosphere Mesosphere Energetic and Dynamics) and NOAA 15-18 (National Oceanic and Atmospheric Administration) satellites measurements are used to examine the response of the polar MLT (Mesosphere and Lower Thermosphere) temperature to energetic electron precipitation during solar wind stream interfaces (SI). We first investigate the relationship between the ionospheric absorption from the ground based riometer and degree of energetic electron precipitation from the MEPED (Medium Energy Proton and Electron Detectors) on board the NOAA satellites. By interpolating the energetic electron measurements from MEPED instruments, we can obtain the electron precipitation rates close in time to the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) temperature retrieval. Using measurements sorted over the vicinity of SANAE IV (South Africa National Antarctic Expedition IV), we investigate if there are significant temperature effects in the MLT altitude on SI arrival at Earth. The preliminary analysis indicate that there are no temperature increase below 100 km prior to the SI triggered precipitation; whereas a clear temperature increase is observed at 95 km immediately after the SI impact. The analysis on the SI geophysical properties indicates that an enhanced magnetospheric convection resulting to heating could be responsible for the temperature modification on SI arrival.

  18. Titan's winter polar vortex structure revealed by chemical tracers

    NASA Astrophysics Data System (ADS)

    Teanby, N. A.; de Kok, R.; Irwin, P. G. J.; Osprey, S.; Vinatier, S.; Gierasch, P. J.; Read, P. L.; Flasar, F. M.; Conrath, B. J.; Achterberg, R. K.; Bézard, B.; Nixon, C. A.; Calcutt, S. B.

    2008-12-01

    The winter polar vortex on Saturn's largest moon Titan has profound effects on atmospheric circulation and chemistry and for the current northern midwinter season is the major dynamical feature of Titan's stratosphere and mesosphere. We use 2 years of observations from Cassini's composite infrared spectrometer to determine cross sections of five independent chemical tracers (HCN, HC3N, C2H2, C3H4, and C4H2), which are then used to probe dynamical processes occurring within the vortex. Our results provide compelling evidence that the vortex acts as a strong mixing barrier in the stratosphere and mesosphere, effectively separating a tracer-enriched air mass in the north from air at lower latitudes. In the mesosphere, above the level of the vortex jet, a tracer-depleted zone extends away from the north pole toward the equator and enrichment is confined to high northern latitudes. However, below this level, mixing processes cause tongues of gas to extend away from the polar region toward the equator. These features are not reproduced by current general circulation models and suggest that a residual polar circulation is present and that waves and instabilities form a more important part of Titan's atmospheric dynamics than previously thought. We also observe an unexpected enrichment of C4H2 in the northern stratosphere, which suggests photochemical polymerization of C2H2. Our observations provide stringent new constraints for dynamical and photochemical models and identify key polar processes for the first time. Some of the processes we see have analogues in Earth's polar vortex, while others are unique to Titan.

  19. Modeling of long-term change in the mesosphere: Radiative and dynamical mechanisms

    NASA Astrophysics Data System (ADS)

    Gruzdev, A.; Brasseur, G.

    We have used the interactive two-dimensional model, SOCRATES, to investigate the response of the thermal structure and chemical composition of the mesosphere to the changes in greenhouse gas concentrations (CO2, CH4, water vapor, N2O, CFCs) observed for the past 50 years, and the response to specified changes in gravity wave drag and diffusion in the upper mesosphere. When considering the observed increase in the abundances of greenhouse gases for the past 50 years, a cooling of 3-7 K has been calculated in the mesopause region together with a cooling of 4-6 K in the middle mesosphere. These effects are significantly lower than the cooling suggested by observations. Increased gravity wave drag and diffusion in the upper mesosphere results in a calculated cooling of several Kelvin in this region of the atmosphere. Larger cooling occurs in the winter upper mesosphere-mesopause region when the observed increase in concentrations of greenhouse gases and the strengthening of the gravity wave drag and diffusion are considered simultaneously in the model. In summer, consistently with observations, a thermal effect in this layer is insignificant, while a significant cooling (˜ 10 K and more) occurs in the middle mesosphere. Depending on the adopted strengthening of the gravity wave drag and diffusion, the cooling in the northern hemisphere extratropical mesopause layer in winter varies from 6-10 K to 10-20 K. The cooling of the mesopause is associated with the significant predicted increase in abundances of methane and water vapor in the upper mesosphere, and with the increase in the divergence of the vertical diffusive flux of heat (downward) in this region, due to enhanced diffusive transport of heat and species in the region of intense gravity wave breaking. Although the calculated cooling of the winter mesopause is still less than suggested by observations, these results lead to the conclusion that the increase in abundances of greenhouse gases alone could not explain

  20. Development of ultra thin polyethylene balloons for research at mesospheric altitude

    NASA Astrophysics Data System (ADS)

    Buduru, Suneel Kumar; Shankarnarayan, Sreenivasan; Ojha, Devendra; Korra, Sakram; Godi, Stalin Peter; Neerudu, Nagendra; Vasudevan, Rajagopalan

    TIFR Balloon facility had initiated development work during 2011 on ultra-thin polyethylene film balloons capable of penetrating mesosphere to meet the needs of user scientists working in the area of atmospheric dynamics. Pursuant to the successful trials with 61,000 cubic meter balloon made out of 3.8 micro meter Antrix film reaching strato-pause (48 kilometers) for the first time in the history of Balloon facility in the year 2012, fine tuning of launch parameters like percentage free lift, launch technique were carried out to take the same volume balloons to higher altitudes in mesosphere. Three successful balloon flights with a total suspended load of 10 kilograms using 61,000 cubic meter balloon were carried out in the month of January 2014 and all the three balloons crossed in to the mesosphere reaching altitudes of over 51 kilometers. All the balloons flown so far are closed system with no escape ducts. A larger single capped balloon of volume 152,000 cubic meter fabricated out of 5.2 micro meter Antrix film as shell and 8 micro meter Antrix film as external cap having length of 25 meters with side escape ducts and 22 kilogram breaking strength load tapes, capable of carrying 15 kilograms suspended load to penetrate mesosphere is awaiting launch during summer 2014 flight program. Balloon fabrication, development of launch hardware, flight control instruments and launch technique for these mesosphere balloon flights is discussed in this paper.

  1. Polarized cells, polar actions.

    PubMed

    Maddock, J R; Alley, M R; Shapiro, L

    1993-11-01

    The recognition of polar bacterial organization is just emerging. The examples of polar localization given here are from a variety of bacterial species and concern a disparate array of cellular functions. A number of well-characterized instances of polar localization of bacterial proteins, including the chemoreceptor complex in both C. crescentus and E. coli, the maltose-binding protein in E. coli, the B. japonicum surface attachment proteins, and the actin tail of L. monocytogenes within a mammalian cell, involve proteins or protein complexes that facilitate bacterial interaction with the environment, either the extracellular milieux or that within a plant or mammalian host. The significance of this observation remains unclear. Polarity in bacteria poses many problems, including the necessity for a mechanism for asymmetrically distributing proteins as well as a mechanism by which polar localization is maintained. Large structures, such as a flagellum, are anchored at the pole by means of the basal body that traverses the peptidoglycan wall. But for proteins and small complexes, whether in the periplasm or the membrane, one must invoke a mechanism that prevents the diffusion of these proteins away from the cell pole. Perhaps the periplasmic proteins are retained at the pole by the presence of the periseptal annulus (35). The constraining features for membrane components are not known. For large aggregates, such as the clusters of MCP, CheA, and CheW complexes, perhaps the size of the aggregate alone prevents displacement. In most cases of cellular asymmetry, bacteria are able to discriminate between the new pole and the old pole and to utilize this information for localization specificity. The maturation of new pole to old pole appears to be a common theme as well. Given numerous examples reported thus far, we propose that bacterial polarity displays specific rules and is a more general phenomenon than has been previously recognized.

  2. In-flight calibration of mesospheric rocket plasma probes

    SciTech Connect

    Havnes, Ove; Hartquist, Thomas W.; Kassa, Meseret; Morfill, Gregor E.

    2011-07-15

    Many effects and factors can influence the efficiency of a rocket plasma probe. These include payload charging, solar illumination, rocket payload orientation and rotation, and dust impact induced secondary charge production. As a consequence, considerable uncertainties can arise in the determination of the effective cross sections of plasma probes and measured electron and ion densities. We present a new method for calibrating mesospheric rocket plasma probes and obtaining reliable measurements of plasma densities. This method can be used if a payload also carries a probe for measuring the dust charge density. It is based on that a dust probe's effective cross section for measuring the charged component of dust normally is nearly equal to its geometric cross section, and it involves the comparison of variations in the dust charge density measured with the dust detector to the corresponding current variations measured with the electron and/or ion probes. In cases in which the dust charge density is significantly smaller than the electron density, the relation between plasma and dust charge density variations can be simplified and used to infer the effective cross sections of the plasma probes. We illustrate the utility of the method by analysing the data from a specific rocket flight of a payload containing both dust and electron probes.

  3. In-flight calibration of mesospheric rocket plasma probes.

    PubMed

    Havnes, Ove; Hartquist, Thomas W; Kassa, Meseret; Morfill, Gregor E

    2011-07-01

    Many effects and factors can influence the efficiency of a rocket plasma probe. These include payload charging, solar illumination, rocket payload orientation and rotation, and dust impact induced secondary charge production. As a consequence, considerable uncertainties can arise in the determination of the effective cross sections of plasma probes and measured electron and ion densities. We present a new method for calibrating mesospheric rocket plasma probes and obtaining reliable measurements of plasma densities. This method can be used if a payload also carries a probe for measuring the dust charge density. It is based on that a dust probe's effective cross section for measuring the charged component of dust normally is nearly equal to its geometric cross section, and it involves the comparison of variations in the dust charge density measured with the dust detector to the corresponding current variations measured with the electron and/or ion probes. In cases in which the dust charge density is significantly smaller than the electron density, the relation between plasma and dust charge density variations can be simplified and used to infer the effective cross sections of the plasma probes. We illustrate the utility of the method by analysing the data from a specific rocket flight of a payload containing both dust and electron probes.

  4. Mesospheric gravity wave momentum flux estimation using hybrid Doppler interferometry

    NASA Astrophysics Data System (ADS)

    Spargo, Andrew J.; Reid, Iain M.; MacKinnon, Andrew D.; Holdsworth, David A.

    2017-06-01

    Mesospheric gravity wave (GW) momentum flux estimates using data from multibeam Buckland Park MF radar (34.6° S, 138.5° E) experiments (conducted from July 1997 to June 1998) are presented. On transmission, five Doppler beams were symmetrically steered about the zenith (one zenith beam and four off-zenith beams in the cardinal directions). The received beams were analysed with hybrid Doppler interferometry (HDI) (Holdsworth and Reid, 1998), principally to determine the radial velocities of the effective scattering centres illuminated by the radar. The methodology of Thorsen et al. (1997), later re-introduced by Hocking (2005) and since extensively applied to meteor radar returns, was used to estimate components of Reynolds stress due to propagating GWs and/or turbulence in the radar resolution volume. Physically reasonable momentum flux estimates are derived from the Reynolds stress components, which are also verified using a simple radar model incorporating GW-induced wind perturbations. On the basis of these results, we recommend the intercomparison of momentum flux estimates between co-located meteor radars and vertical-beam interferometric MF radars. It is envisaged that such intercomparisons will assist with the clarification of recent concerns (e.g. Vincent et al., 2010) of the accuracy of the meteor radar technique.

  5. Arctic Strato-Mesospheric Temperature and Wind Variations

    NASA Technical Reports Server (NTRS)

    Schmidlin, F. J.; Goldberg, R. A.

    2004-01-01

    Upper stratosphere and mesosphere rocket measurements are actively used to investigate interaction between the neutral, electrical, and chemical atmospheres and between lower and upper layers of these regions. Satellite temperature measurements from HALOE and from inflatable falling spheres complement each other and allow illustrations of the annual cycle to 85 km altitude. Falling sphere wind and temperature measurements reveal variability that differs as a function of altitude, location, and time. We discuss the state of the Arctic atmosphere during the summer 2002 (Andoya, Norway) and winter 2003 (ESRANGE, Sweden) campaigns of MaCWAVE. Balloon-borne profiles to 30 km altitude and sphere profiles between 50 and 90 km show unique small-scale structure. Nonetheless, there are practical implications that additional measurements are very much needed to complete the full vertical profile picture. Our discussion concentrates on the distribution of temperature and wind and their variability. However, reliable measurements from other high latitude NASA programs over a number of years are available to help properly calculate mean values and the distribution of the individual measurements. Since the available rocket data in the Arctic's upper atmosphere are sparse the results we present are basically a snapshot of atmospheric structure.

  6. Mesospheric Water Vapor Retrieved from SABER/TIMED Measurements

    NASA Technical Reports Server (NTRS)

    Feofilov, Arte, G.; Yankovsky, Valentine A.; Marshall, Benjamin T.; Russell, J. M., III; Pesnell, W. D.; Kutepov, Alexander A.; Goldberg, Richard A.; Gordley, Larry L.; Petelina, Svetlama; Mauilova, Rada O.; Garaci-A-Comas, M.

    2007-01-01

    The SABER instrument on board the TIMED satellite is a limb scanning infrared radiometer designed to measure temperature and minor constituent vertical profiles and energetics parameters in the mesosphere and lower thermosphere (MLT) The H2O concentrations are retrieved from 6.3 micron band radiances. The interpretation of this radiance requires developing a non-LTE H2O model that includes energy exchange processes with the system of O3 and O2 vibrational levels populated at the daytime through a number of photoabsorption and photodissociation processes. We developed a research model base on an extended H2O non-LTE model of Manuilova coupled with the novel model of the electronic kinetics of the O2 and O3 photolysis products suggested by Yankosvky and Manuilova. The performed study of this model helped u to develop and test an optimized operational model for interpretation of SABER 6.3 micron band radiances. The sensitivity of retrievals to the parameters of the model is discussed. The H2O retrievals are compared to other measurements for different seasons and locations.

  7. Global and Seasonal Distributions of Mesospheric OH Emissions from SABER

    NASA Astrophysics Data System (ADS)

    Baker, D. J.; Fielding, R. L.; Aston, R. C.; Hancock, J. J.; Reese, K. B.; Mlynczak, M. G.; Russell, J. M.

    2004-12-01

    On December 7, 2001, SABER, a cooled multichannel radiometer, was launched aboard the TIMED satellite. In January of 2002 the SABER instrument began returning airglow limb scan measurements from around the globe. Data now available include 65% of 2002, 75% of 2003, and 40% of 2004. Experimental data were taken from SABER for two radiometric channels centered at λ =1.6 μ m and 2.06 μ m. Volume emission rates (VER) were computed at the peaks of the OH layer profiles and then the magnitudes were displayed as a function of the latitude and longitude of the tangent point of the observation. The Mlynczak unfiltering algorithm for OH emissions was used to obtain absolute values for the maximum VER of the total sequence of OH vibration-rotation band emissions. The maximum VER was found to be greater near the equator compared with high latitudes. In addition, seasonal effects on the global distribution of the nighttime OH airglow were explored for the available data in 2002, 2003, and part of 2004. Algorithmic methods of optimized geographic visualization for this unprecedented wealth of mesospheric airglow data were also explored.

  8. Silicon chemistry in the mesosphere and lower thermosphere

    PubMed Central

    Gómez‐Martín, Juan Carlos; Feng, Wuhu; Janches, Diego

    2016-01-01

    Abstract Silicon is one of the most abundant elements in cosmic dust, and meteoric ablation injects a significant amount of Si into the atmosphere above 80 km. In this study, a new model for silicon chemistry in the mesosphere/lower thermosphere is described, based on recent laboratory kinetic studies of Si, SiO, SiO2, and Si+. Electronic structure calculations and statistical rate theory are used to show that the likely fate of SiO2 is a two‐step hydration to silicic acid (Si(OH)4), which then polymerizes with metal oxides and hydroxides to form meteoric smoke particles. This chemistry is then incorporated into a whole atmosphere chemistry‐climate model. The vertical profiles of Si+ and the Si+/Fe+ ratio are shown to be in good agreement with rocket‐borne mass spectrometric measurements between 90 and 110 km. Si+ has consistently been observed to be the major meteoric ion around 110 km; this implies that the relative injection rate of Si from meteoric ablation, compared to metals such as Fe and Mg, is significantly larger than expected based on their relative chondritic abundances. Finally, the global abundances of SiO and Si(OH)4 show clear evidence of the seasonal meteoric input function, which is much less pronounced in the case of other meteoric species. PMID:27668138

  9. Mesospheric Water Vapor Retrieved from SABER/TIMED Measurements

    NASA Technical Reports Server (NTRS)

    Feofilov, Arte, G.; Yankovsky, Valentine A.; Marshall, Benjamin T.; Russell, J. M., III; Pesnell, W. D.; Kutepov, Alexander A.; Goldberg, Richard A.; Gordley, Larry L.; Petelina, Svetlama; Mauilova, Rada O.; hide

    2007-01-01

    The SABER instrument on board the TIMED satellite is a limb scanning infrared radiometer designed to measure temperature and minor constituent vertical profiles and energetics parameters in the mesosphere and lower thermosphere (MLT) The H2O concentrations are retrieved from 6.3 micron band radiances. The interpretation of this radiance requires developing a non-LTE H2O model that includes energy exchange processes with the system of O3 and O2 vibrational levels populated at the daytime through a number of photoabsorption and photodissociation processes. We developed a research model base on an extended H2O non-LTE model of Manuilova coupled with the novel model of the electronic kinetics of the O2 and O3 photolysis products suggested by Yankosvky and Manuilova. The performed study of this model helped u to develop and test an optimized operational model for interpretation of SABER 6.3 micron band radiances. The sensitivity of retrievals to the parameters of the model is discussed. The H2O retrievals are compared to other measurements for different seasons and locations.

  10. Development of Mesospheric Sodium Laser Beacon for Atmospheric Adaptive Optics

    NASA Technical Reports Server (NTRS)

    Jeys, T. H.

    1992-01-01

    A solid-state source of long pulse length, sodium-resonance radiation was developed for the purpose of generating an artificial star in the earth's mesospheric sodium layer. This radiation is generated by sum-frequency mixing the output of a 1.064 micron Nd:YAG laser with the output of a 1.319-micron Nd:YAG laser. By operating these lasers at wavelengths very close to the peak of their tuning curves, it is possible to match the wavelength of the sum-frequency radiation to that of the sodium D2