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Sample records for matter polar mesosphere

  1. Chemical definition of the mesospheric polar vortex

    NASA Astrophysics Data System (ADS)

    Harvey, V. L.; Randall, C. E.; Collins, R. L.

    2015-10-01

    We present a simple chemical definition to demark the edge of the mesospheric polar vortices. Because this vortex definition does not rely on the wind field, it is useful in the mesosphere where wind observations are sparse and reanalysis winds are unreliable. The chemical definition is also insensitive to double jets that complicate vortex identification in the mesosphere. The algorithm is based on horizontal gradients of carbon monoxide (CO) and mirrors the widely used vortex edge definition in the stratosphere based on potential vorticity (PV) gradients. Here the approach is used to identify the Arctic vortex in the mesosphere during a 10 year (2004-2014) record of Microwave Limb Sounder data. Vortex size and shape comparisons are made where the CO and PV methods overlap in the upper stratosphere. A case study is presented during the NH 2008-2009 winter that demonstrates the fidelity of the CO gradient method on individual days and emphasizes the impact of double jets on methods to identify the polar vortex. We recommend transitioning from a PV or stream function-based vortex definition in the stratosphere to using a CO gradient definition above 0.1 hPa (~60 km). The CO gradient method identifies a coherent region of high CO at 80 km that is confined to mid-to-high latitudes 99.8% of the time during Arctic winter. Taking advantage of the CO gradient method to identify the polar vortex adds ~20 km of reliable vortex information (from 60 to 80 km) in a region of the atmosphere where reanalyses are most suspect.

  2. 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.

  3. Removal of meteoric iron on polar mesospheric clouds.

    PubMed

    Plane, John M C; Murray, Benjamin J; Chu, Xinzhao; Gardner, Chester S

    2004-04-16

    Polar mesospheric clouds are thin layers of nanometer-sized ice particles that occur at altitudes between 82 and 87 kilometers in the high-latitude summer mesosphere. These clouds overlap in altitude with the layer of iron (Fe) atoms that is produced by the ablation of meteoroids entering the atmosphere. Simultaneous observations of the Fe layer and the clouds, made by lidar during midsummer at the South Pole, demonstrate that essentially complete removal of Fe atoms can occur inside the clouds. Laboratory experiments and atmospheric modeling show that this phenomenon is explained by the efficient uptake of Fe on the ice particle surface.

  4. 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.

  5. Particle size distributions in polar mesospheric clouds derived from solar mesosphere explorer measurements

    NASA Technical Reports Server (NTRS)

    Rusch, D. W.; Thomas, G. E.; Jensen, E. J.

    1991-01-01

    Data from the visible and UV spectrometers on the Solar Mesosphere Explorer are used to derive the color ratios of the reflectance at 265, 296, and 393 nm of light scattered from polar mesospheric cloud particles. This analysis extends the spectral coverage into the visible region of the spectrum. The data reduction technique compared the cloud brightness to the brightness scattered from the background atmosphere at the same wavelength. The ratios determined in this way are independent of systematic errors in instrument radiometric calibration. The data are analyzed using theoretical determinations of the color ratios from the Mie theory of small particle scattering, assuming a lognormal distribution for the particle size dispersion. Here 'size' means the average radius of the sphere having the same ice volume. The present results confirm earlier findings that the effective sizes of polar mesospheric cloud particles are less than 70 nm. Still, there exists a small number of measurements which result in particle sizes of the order of 80 nm. Even for these large particle sizes the required vertical column content of water vapor does not exceed limits imposed by the available atmospheric water vapor concentrations.

  6. 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.

  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., Jr.; Siskind, D. E.; Bailey, S. M.; Russell, J. M., III

    2014-12-01

    The NASA Aeronomy of Ice in the Mesosphere (AIM) satellite is the first satellite mission dedicated to studying polar mesospheric clouds (PMCs). In particular, the Cloud Imaging and Particle Size (CIPS) instrument onboard AIM obtains large-field PMC images enabling a unique investigation of the mesospheric gravity waves, as the satellite traverses over the summer polar regions. The high quality of CIPS data has provided an exceptional capability to investigate the gravity wave signatures in the summer polar mesosphere where previous measurements have been sparse. We have utilized 12 consecutive seasons of AIM/CIPS PMC albedo data to derive the statistical properties of a broad spectrum of gravity waves present in the PMC data. Over 60,000 waves with horizontal scale sizes ranging from ~50 to >2000 km were identified and measured, revealing a well-developed, consistent distribution for their horizontal wavelengths with a peak in occurrence frequency centered around 400 km. The same result was found from season to season and in both hemispheres. Throughout this study, the wave activity in the southern hemisphere was found to be 10-15% higher than in the northern hemisphere and both northern and southern wave activity was found to decrease systematically (average ~15%) during the course of each summer season. We present new results of the intra-seasonal, inter-annual and hemispheric variability of these waves observed over the whole summer polar cap regions. The systematic decrease in wave activity is consistent with background wind filtering in the northern hemisphere but is not apparently associated with the critical level filtering in the southern hemisphere.

  8. Polar Mesospheric Cloud Prediction and Observation

    NASA Astrophysics Data System (ADS)

    Kendra, M. J.; Griffin, J. M.

    2006-05-01

    A microphysical model for PMC formation was run within the SHARC Atmosphere Generator (SAG), a stand- alone set of empirical models used to generate atmospheric profiles for IR radiance codes. The PMC model determines the saturation ratio of water vapor over ice for a range of altitudes and conditions of interest. Model results are compared to PMC observations in the infrared by the MSX SPIRIT III radiometer. Infrared measurements of PMC were recorded in two long wavelength infrared (LWIR) radiometer bands, 11.1 to 13.2 and 18.1 to 26.0 microns, on several occasions in the northern polar region during July 1996. Recent studies based on the refractive index of water ice have shown that PMC radiance in these LWIR bands is relatively insensitive to the solar scattering angle and only moderately dependent on temperature, which allows straightforward interpretation of the MSX observations. PMC radiance in the 11.1 to 13.2 micron band was much greater than ambient background levels, facilitating detailed comparison between model prediction and IR measurement. These and other predictive results will be presented.

  9. 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

  10. Large amplitude nonlinear structures in the nighttime polar mesosphere

    NASA Astrophysics Data System (ADS)

    Maharaj, Shimul K.; Bharuthram, Ramashwar; Singh Lakhina, Gurbax; Muralikrishna, Polinaya; Singh, Satyavir

    2016-07-01

    The existence of large amplitude potential structures will be investigated for a plasma composed of negative ions, positive ions, electrons and an additional fourth component of charged (usually positive) nano-sized ions in an attempt to model the plasma composition in the nighttime polar mesosphere (˜80 - 90 km altitude) [1]. The fourth ionic component becomes positively charged if there is a high enough concentration of negative ions which are sufficiently heavy. The positive charge on the fourth component can be explained by the capture of currents, and is not a result of photo-emission and secondary electron emission processes. Consequently, if the negative ions are much lighter, then the fourth ion component will become negatively charged. The charged ion species will be treated as inertial species which are cold or adiabatic, whilst the electrons will be considered to be Boltzmann-distributed (isothermal). Taking into consideration not only the dynamics of the heaviest species (dust-acoustic) but also the lighter ions (ion-acoustic), the theoretical study will use the Sagdeev pseudo-potential formalism to explore the existence of arbitrary amplitude solitons and double layer potential structures. [1] Observations of positively charged nanoparticles in the nighttime polar mesosphere, M. Rapp, J. Hedin, I. Strelnikova, M. Friederich, J. Gumbel, and F.˜J. Lübken, Geophys. Res. Letters. 32, L23821, doi:10.1029/2005GL024676 (2005).

  11. 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.

  12. Unique High-Resolution Stratospheric Observations of Polar Mesospheric Clouds

    NASA Astrophysics Data System (ADS)

    Miller, A.; Araujo, D.; Chapman, D.; Didier, J.; Fritts, D. C.; Jones, G.; Kjellstrand, B.; Limon, M.; Lizancos, A.; Luu, T. V.; Macioce, T.; Tucker, G.; Vinokurov, J.

    2014-12-01

    We present a unique data set consisting of high-resolution optical images of Polar Mesospheric Clouds (PMCs), observed serendipitously from a stratospheric balloon platform in January of 2013. Complex morphological structures in the PMC brightness distribution provide observable consequences of the deposition of energy and momentum by atmospheric gravity waves in the mesosphere and lower thermosphere. This data set represents the highest resolution set of optical images of this phenomenon to date, and therefore provides a unique window into the poorly understood instability and turbulent dynamics on the smallest scales (between roughly a meter and a few km). Through this analysis, morphological features identified in individual images will be compared with those predicted in numerical models in order to identify key dynamical features present in the data on these small scales. Multiple spatially-overlapping sequential images will be analyzed together in order to extract cloud velocities and to measure timescales for feature permanence. These image compilations will also be used to place the observed small-scale features in a broader context by using multiple images to re-construct larger features, as well as to compare to features simultaneously observed on much larger scales by the CIPS instrument flying on the AIM satellite.

  13. 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.

  14. 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.

  15. The Mesospheric Polar Vortices in GEOS, WACCM, SABER, and EOS-MLS

    NASA Astrophysics Data System (ADS)

    Harvey, V.; Randall, C. E.; Pawson, S.; Garcia, R.; Lieberman, R.; Manney, G. L.

    2007-12-01

    Satellite data analysis is combined with global modeling to characterize the 3-D structure and day-to-day variability of the polar vortex in the mesosphere. We use satellite temperature and geopotential height data from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument and temperature, carbon monoxide, and methane data from the Microwave Limb Sounder (MLS) instrument to characterize the structure of the upper stratospheric and mesospheric polar vortex in each hemisphere on a daily basis. The mesospheric vortex, as seen by these satellite instruments, is then compared to the representation of the mesospheric vortex in the GEOS-4 and GEOS-5 data assimilation systems as well as in the Whole Atmosphere Community Climate Model (WACCM). We will show the 3-D structure of the mesospheric vortex at times when the stratospheric vortex is strong as well as how this structure is modified during stratospheric warming events. This work will conduct model/observation intercomparisons of the mesospheric vortex to further understanding of its role in the descent of EPP-NOx.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. Stratospheric Ozone Changes and Polar Mesospheric Cloud (PMC) Trends Observed in SBUV Data

    NASA Astrophysics Data System (ADS)

    DeLand, M. T.; Thomas, G. E.; Shettle, E. P.; Olivero, J. J.

    2013-12-01

    Polar mesospheric clouds (PMCs) are observed at 80-85 km altitude and high latitudes (typically > 50°) only during summer months. It has been suggested that long-term variations of PMC occurrence frequency and brightness are indicators of global climate change as represented through changes in mesospheric temperature and water vapor. The Solar Backscatter Ultraviolet (SBUV) series of satellite instruments, although designed to measure stratospheric profile and total column ozone, have made global observations of bright PMCs since November 1978. Previous analysis of SBUV data found that long-term variations in PMC brightness and occurrence frequency were anti-correlated with solar activity, and that a positive secular trend was present at most latitudes. The limited database of mesospheric temperature and water vapor data has precluded further determination of the source of this trend. Motivated by recent studies with the LIMA general circulation model [Berger and Lübken 2011], which relate mesospheric temperature trends to changes in stratospheric ozone, we have investigated the use of stratospheric ozone changes as a proxy for changes in mesospheric heating and temperature. The decrease in ozone from 1979 to the mid-1990s leads to a cooler mesosphere, and is thus consistent with the rise in PMC ice water content observed in the SBUV record during this period. Similarly, stratospheric ozone changes are smaller from the mid-1990s to the present, and PMC ice water content trends are also reduced in recent years. We will discuss these results and their implications for both previous (before 1979) and future PMC behavior.

  1. 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.

  2. 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.

  3. 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.

  4. Frequency domain interferometry of polar mesosphere summer echoes with the EISCAT VHF radar - A case study

    NASA Astrophysics Data System (ADS)

    Franke, S. J.; Roettger, J.; Lahoz, C.; Liu, C. H.

    1992-06-01

    During the polar mesosphere summer echo (PMSE) campaign in 1988 the first multiple-frequency mesospheric measurements were carried out using EISCAT 224-MHz radar. A case study of nearly simultaneous measurements of coherent backscatter, collected on two closely spaced frequencies on July 3, 1988, is presented. The data are used to investigate the frequency coherence of the radar echoes and to perform frequency domain interferometry (FDI) analysis. The FDI techniques provides precise information about the thickness and relative position of isolated scattering layers. The results indicate that scattering layers with thicknesses in the range 85-120 m are sometimes present in the polar summer mesosphere. Such a layer is shown to exist for a period of approximately 10 min, and its position is tracked as it descends over more than 1 km in altitude and transits from one range gate to the next. In addition, the FDI technique is used to study a case where a sudden frequency jump is observed in the Doppler spectrum.

  5. 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

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. Assymetry in the Polar Mesosphere Revealed by the 2012 Venus Transit Aureole

    NASA Astrophysics Data System (ADS)

    Widemann, Thomas; Tanga, P.; Reardon, K. P.; Limaye, S.; Wilson, C.; Vandaele, A.; Wilquet, V.; Mahieux, A.; Robert, S.; Pasachoff, J. M.; Schneider, G.

    2012-10-01

    Close to ingress and egress phases, the fraction of Venus disk projected outside the solar photosphere appears outlined by an irregular thin arc of light called the "aureole." We have shown that the deviation due to refraction and the aureole intensity are related to the local density scale height and the altitude of the refraction layer (Tanga et al. 2012). Since the aureole brightness is the quantity that can be measured during the transit, an appropriate model allows us to determine both parameters. We now compare this model developed for the 2004 data to the first results of 2012 campaign. Ingress pictures of NASA's SDO/HMI observations, OP-OCA/VTE coronagraph observations at Haleakala and Lowell stations, and Dunn/IBIS observations at Sacramento Peak, NM, show latitudinal structure of the aureole during the ingress phase of the Venus transit. For the HMI data, the temporal cadence is 3.75 sec and the pixel scale is 0.5 arcsec/pixel. The polar region, significantly brighter in initial phases due to the larger scale height of the polar mesosphere, appears consistently offset toward morning terminator by about 15 deg. latitude, peaking at 75N at 6:00 local time. This result reflects local latitudinal structure in the polar mesosphere, either in temperature or aerosol altitude distribution. Relation with ESA / Venus Express / SOIR simultaneous measurements and dynamical interpretation will be discussed at the meeting. Tanga et al. 2012, Icarus 218, 207-219

  11. 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.

  12. 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.

  13. 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.

  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. 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

  16. What can be learned about Polar Mesospheric Clouds from suborbital missions?

    NASA Astrophysics Data System (ADS)

    Thomas, G. E.; McClintock, W.; Fritts, D. C.

    2011-12-01

    Noctilucent clouds ('night luminous' or NLC) are the highest and coldest clouds in the atmosphere. When viewed from the ground they are referred to as NLC. Viewed from space they are called Polar Mesospheric Clouds, or PMC. Occupying a narrow (81-86 km) height zone below the high-latitude mesopause (a temperature minimum versus height, located near 88 km), NLC offer a splendid sight during summer twilights. They are made visible by scattered sunlight against the dark twilight sky, when the sun lies below the horizon at angles between 6o and 16o. The state of the science has been advanced significantly since the launches of the Odin and Aeronomy of Ice in the Mesosphere (AIM) satellite missions. The spatial scales of the clouds are evident in the Cloud Imaging and Particle Size (CIPS) experiment down to its limiting resolution of 5 km. However, from ground-based photography of NLC, and from theoretical modeling of small-scale 3D instability and turbulence dynamics in the upper mesosphere, we know that there is much structure on the sub-km scale which is yet to be explored. Turbulent breakdown is expected to occur in this sub-km range. Fortunately, on the short-time scales of turbulence, ice particles should act as passive tracers, which are advected by the wind field. Sub-orbital missions provide an ideal observing platform for extending the PMC 'spatial spectrum' ranging currently from hundreds to tens of km (which we now know from CIPS) down to tens of meters, a 'leap' of three orders of magnitude. A high resolution camera with a CMOS chip, is easily capable of sub-km resolution, with S/N ratios exceeding 100 for a bright PMC. A wide (150 nm) bandpass centered on the blue portion of the PMC spectrum isolates the most intense portion of the scattered brightness. Movies of the clouds as the sub-orbital vehicle approaches, and penetrates the cloud, would be valuable, both for the scientific goal of studying the 'transition to turbulence', but also for educational

  17. 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

  18. 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.

  19. 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

  20. 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

  1. 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.

  2. 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.

  3. 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

  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.

    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

  5. Neutral air turbulence and temperatures in the vicinity of polar mesosphere summer echoes

    NASA Astrophysics Data System (ADS)

    Lübken, Franz-Josef; Rapp, Markus; Hoffmann, Peter

    2002-08-01

    A total of 8 sounding rocket flights with measurements of neutral air turbulence in the upper mesosphere have been performed in the past 10 years with simultaneous and nearly co-located radar measurements of polar mesosphere summer echoes (PMSE). These measurements took place close to the rocket ranges in northern Norway (Andøya Rocket Range, 69°N) and in northern Sweden (Esrange, 68°N). A detailed comparison demonstrates that there is no apparent correlation between PMSE and neutral air turbulence and that in fact turbulence is absent in the majority of all PMSE events (no turbulence in 7 out of 10 PMSE layers). This suggests that neutral turbulence and other mechanisms affecting the neutral atmosphere at very small spatial scales play a minor role in creating PMSE, contrary to the speculations published in the literature. The main mechanism for creating PMSE remains unidentified. A comparison of PMSE with simultaneous temperature profiles derived from falling sphere and ionization gauge measurements shows that PMSE are practically always present at altitudes where the temperature is low enough for water ice particles to exist. This supports the general understanding that PMSE are closely related to charged water ice particles. On the other hand, the measurements also demonstrate that low enough temperatures are not sufficient for PMSE to exist. Temperature lapse rates were deduced from the high-altitude-resolution ionization gauge measurements. Within the PMSE layers the temperature lapse rate is typically +1-2 K/km with a rather large variability of +/-5-10 K/km. Adiabatic lapse rates have never been found within a PMSE layer, which suggests that turbulence cannot have been active for a substantial period. This again supports the idea that neutral air turbulence plays a minor role in creating PMSE. Probably the only common physical reason for PMSE and turbulence is the background temperature profile, which supports the creation of ice particles (since

  6. 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.

  7. 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.

  8. The roles of temperature and water vapor at different stages of the polar mesospheric cloud season

    NASA Astrophysics Data System (ADS)

    Rong, P. P.; Russell, J. M., III; Hervig, M. E.; Bailey, S. M.

    2012-02-01

    Temperature, or alternatively, saturation vapor pressure (PSAT), dominantly controls the polar mesospheric cloud (PMC) seasonal onset and termination, characterized by a strong anticorrelated relationship between the Solar Occultation for Ice Experiment (SOFIE)-observed PMC frequency and PSAT on intraseasonal time scales. SOFIE is highly sensitive to weak clouds and can obtain a nearly full spectrum of PMCs. Both the SOFIE PMC frequency and PSAT indicate a rapid onset and termination of the season. Compared to PSAT, the water vapor partial pressure (PH2O) exhibits only a slight increase from before to after the start of the season. We are able to use the PSAT daily minimum and two averaged PH2O levels taken before and after the solstice, respectively, to estimate the start and end days of the PMC season within 1-2 days uncertainty. SOFIE ice mass density and its relationship to PH2O and PSAT are examined on intraseasonal scales and for two extreme conditions, i.e., strong and weak cloud cases. In the strong cloud case, such as those bright clouds that occur during the core of the season, PH2O far exceeds PSAT and dominantly controls the ice mass density variation, while in the weak cloud case, such as those clouds that occur at the start and end of the season, PH2O and PSAThave comparable magnitudes, vary in concert, and have similar effects on the ice mass density variation. These results suggest that the long-term brightness trends reported by DeLand et al. (2007) are primarily driven by changes in water vapor (H2O), not temperature.

  9. 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.

  10. CIPS/AIM Observation of Polar Mesospheric Cloud Structures and NOGAPS-ALPHA Analysis of the Environment in Which These Structures Form

    NASA Astrophysics Data System (ADS)

    Thurairajah, B.; Bailey, S. M.; Siskind, D. E.; Lumpe, J. D.; Nielsen, K.; Randall, C. E.; Taylor, M. J.; Russell, J.

    2010-12-01

    The Cloud Imaging and Particle Size (CIPS) experiment on the Aeronomy of Ice in the Mesosphere (AIM) spacecraft images Polar Mesospheric Clouds (PMCs) using four cameras, each operating with a 15 nm passband centered at 265 nm. CIPS has provided images of PMCs containing numerous structures including the presence of 'ice voids'. These ice voids appear as a nearly circular ice free region with dark centers that are sometimes surrounded by an ice ring arc. Ice voids are also structurally similar to tropospheric cloud features and concentric gravity wave structures observed in the mesospheric airglow region. We document CIPS observations of ice voids during the Northern Hemisphere 2007 PMC season. We use the Naval Research Laboratory's Navy Operational Global Atmospheric Prediction System (NOGAPS) Advanced Level Physics and High Altitude (ALPHA) model to analyze what these ice voids can tell us about the mesospheric environment in which they form and what possible connections there may be with the lower atmosphere.

  11. 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

  12. 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.

  13. 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. PMID:19586392

  14. 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.

  15. Mesopause Horizontal wind estimates based on AIM CIPS polar mesospheric cloud pattern matching

    NASA Astrophysics Data System (ADS)

    Rong, P.; Yue, J.; Russell, J. M.; Gong, J.; Wu, D. L.; Randall, C. E.

    2013-12-01

    A cloud pattern matching approach is used to estimate horizontal winds in the mesopause region using Polar Mesospheric Cloud (PMC) albedo data measured by the Cloud Imaging and Particle Size instrument on the AIM satellite. Measurements for all 15 orbits per day throughout July 2007 are used to achieve statistical significance. For each orbit, eighteen out of the twenty-seven scenes are used for the pattern matching operation. Some scenes at the lower latitudes are not included because there is barely any cloud coverage for these scenes. The frame-size chosen is about 12 degrees in longitude and 3 degrees in latitude. There is no strict criterion in choosing the frame size since PMCs are widespread in the polar region and most local patterns do not have a clearly defined boundary. The frame moves at a step of 1/6th of the frame size in both the longitudinal and latitudinal directions to achieve as many 'snap-shots' as possible. A 70% correlation is used as a criterion to define an acceptable match between two patterns at two time frames; in this case the time difference is about 3.6 minutes that spans every 5 'bowtie' scenes. A 70% criterion appears weak if the chosen pattern is expected to act like a tracer. It is known that PMC brightness varies rapidly with a changing temperature and water vapor environment or changing nucleation conditions, especially on smaller spatial scales; therefore PMC patterns are not ideal tracers. Nevertheless, within a short time span such as 3.6 minutes a 70% correlation is sufficient to identify two cloud patterns that come from the same source region, although the two patterns may exhibit a significant difference in the actual brightness. Analysis of a large number of matched cloud patterns indicates that over the 3.6-minute time span about 70% of the patterns remain in the same locations. Given the 25-km2 horizontal resolution of CIPS data, this suggests that the overall magnitude of horizontal wind at PMC altitudes (~80-87 km) in

  16. In-situ measurement of smoke particles in the wintertime polar mesosphere between 80 and 85 km altitude

    NASA Astrophysics Data System (ADS)

    Amyx, K.; Sternovsky, Z.; Knappmiller, S.; Robertson, S.; Horanyi, M.; Gumbel, J.

    2008-01-01

    The MAGIC sounding rocket, launched in January 2005 into the polar mesosphere, carried two detectors for charged aerosol particles. The detectors are graphite patch collectors mounted flush with the skin of the payload and are connected to sensitive electrometers. The measured signal is the net current deposited on the detectors by heavy aerosol particles. The collection of electrons and ions is prevented by magnetic shielding and a small positive bias, respectively. Both instruments detected a layer of heavy aerosol particles between 80 and 85 km with a number density approximately 103 cm-3. Aerodynamic flow simulations imply that the collected particles are larger than ˜1 nm in radius. The particles are detected as a net positive charge deposited on the graphite collectors. It is suggested that the measured positive polarity is due to the electrification of the smoke particles upon impact on the graphite collectors.

  17. Dynamics in the mesosphere and lower thermosphere in the high Arctic: Observations from the Polar Environment Atmospheric Research Laboratory

    NASA Astrophysics Data System (ADS)

    Ward, William E.; Meek, Chris; Shepherd, Marianna; Manson, Alan; Drummond, James; Cho, Young-Min; Kristoffersen, Samuel; Das, Uma; Vail, Christopher

    Observations of the dynamics of the mesosphere and lower thermosphere from the Polar Environment Atmospheric Research Laboratory (PEARL) at Eureka, Nunavut, Canada (80N, 86W) were initiated in 2007. Over the past 7 winters, a suite of instruments has come on line and wind, temperature and airglow measurements from this observatory are now available (www.candac.ca). The instrumentation includes a meteor radar, a spectral airglow temperature imager, a field-widened Michelson interferometer and an all-sky imager. The radar provides hourly wind profiles from 82 to 97 km, and the other instruments provide information on temperature, wind, airglow brightness on a cadence of the order of a few minutes. Mesospheric airglow emissions observed include the oxygen green line, the O _{2} atmospheric band, hydroxyl and sodium. This set of instruments allows detailed analyses of the dynamical signatures over the observatory to be undertaken. Collaborations with observations from other stations and satellite instruments is being initiated. In this paper, the data set is described and interesting results from scientific studies undertaken at PEARL are summarized

  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. An Albedo-Ice Regression Method for Determining Ice Water Content of Polar Mesospheric Clouds from UV Observations

    NASA Astrophysics Data System (ADS)

    Thomas, G. E.; Bardeen, C.; Benze, S.

    2014-12-01

    Simulations of Polar Mesospheric Cloud (PMC) brightness and ice water content (IWC) are used to develop a simple robust method for IWC retrieval from UV satellite observations. We compare model simulations of IWC with retrievals from the UV Cloud Imaging and Particle Size (CIPS) experiment on board the satellite mission Aeronomy for Ice in the Mesosphere (AIM). This instrument remotely senses scattered brightness related to the vertically-integrated ice content. Simulations from the Whole Atmosphere Community Climate Model (WACCM), a chemistry climate model, is combined with a sectional microphysics model based on the Community Aerosol and Radiation Model for Atmospheres (CARMA). The model calculates high-resolution three-dimensional size distributions of ice particles. The internal variability is due to geographic and temporal variation of temperature and dynamics, water vapor, and meteoric dust. We examine all simulations from a single model day (we chose northern summer solstice) which contains several thousand model clouds. Accurate vertical integrations of the albedo and IWC are obtained. The ice size distributions are thus based on physical principles, rather than artificial analytic distributions that are often used in retrieval algorithms from observations. Treating the model clouds as noise-free data, we apply the CIPS algorithm to retrieve cloud particle size and IWC. The inherent "errors" in the retrievals are thus estimated. The linear dependence of IWC on albedo makes possible a method to derive IWC, called the Albedo-Ice regression method, or AIR. This method potentially unifies the variety of data from various UV experiments, with the advantages of (1) removing scattering-angle bias from cloud brightness measurements,(2) providing a physically-useful parameter (IWC),(3) deriving IWC even for faint clouds of small average particle sizes, and (4) estimating the statistical uncertainty as a random error, which bypasses the need to derive particle size.

  20. Horizontal winds derived from the polar mesospheric cloud images as observed by the CIPS instrument on the AIM satellite

    NASA Astrophysics Data System (ADS)

    Rong, P. P.; Yue, J.; Russell, J. M.; Lumpe, J. D.; Gong, J.; Wu, D. L.; Randall, C. E.

    2015-06-01

    A cloud pattern matching technique is applied to polar mesospheric cloud (PMC) images taken by the Cloud Imaging and Particle Size instrument (CIPS) to infer the wind velocities in the mesopause region. CIPS measurements are analyzed to detect patterns that repeat from one orbit to the next but are displaced in location; the displacement provides a measure of the wind velocity. Pattern matching is achieved by resampling the CIPS data to longitude and latitude grids with the grid-box size forced at ~5 km in both directions. The correlated patterns are searched within a geographic region referred to as a "frame" of ~500 km in longitude × 400 km in latitude. The histograms of the derived velocities indicate that easterly winds prevail, with a mean zonal wind of -20 to -15 m/s. Mean meridional winds are overall small, but in late summer the histogram indicated a poleward wind of ~20-30 m/s. The variability of CIPS cloud albedo on consecutive orbits is also examined at fixed geolocations. The statistical results suggest that ~86% of pairs underwent mean cloud albedo variation of < 50% on consecutive orbits, suggesting a moderate change. It is also found that the correlation of the cloud structures between two consecutive orbits at a fixed location is generally poor. These findings suggest that cloud patterns are subject to wind advection, but the cloud patches are more extended in size than the movement that occurs. Cloud voids are found to be more likely to remain at the same geolocations.

  1. 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

  2. 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.

  3. 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.

  4. EISCAT and ESRAD radars observations of polar mesosphere winter echoes during solar proton events on 11-12 November 2004

    NASA Astrophysics Data System (ADS)

    Belova, E.; Kirkwood, S.; Sergienko, T.

    2013-07-01

    Polar mesosphere winter echoes (PMWE) were detected by two radars, ESRAD at 52 MHz located near Kiruna, Sweden, and EISCAT at 224 MHz located near Tromsø, Norway, during the strong solar proton event on 11-12 November 2004. PMWE maximum volume reflectivity was estimated to be 3 × 10-15 m-1 for ESRAD and 2 × 10-18 m-1 for EISCAT. It was found that the shape of the echo power spectrum is close to Gaussian inside the PMWE layers, and outside of them it is close to Lorentzian, as for the standard ion line of incoherent scatter (IS). The EISCAT PMWE spectral width is about 5-7 m s-1 at 64-67 km and 7-10 m s-1 at 68-70 km. At the lower altitudes the PMWE spectral widths are close to those for the IS ion line derived from the EISCAT data outside the layers. At the higher altitudes the PMWE spectra are broader by 2-4 m s-1 than those for the ion line. The ESRAD PMWE spectral widths at 67-72 km altitude are 3-5 m s-1, that is, 2-4 m s-1 larger than ion line spectral widths modelled for the ESRAD radar. The PMWE spectral widths for both EISCAT and ESRAD showed no dependence on the echo strength. It was found that all these facts cannot be explained by turbulent origin of the echoes. We suggested that evanescent perturbations in the electron gas generated by the incident infrasound waves may explain the observed PMWE spectral widths. However, a complete theory of radar scatter from this kind of disturbance needs to be developed before a full conclusion can be made.

  5. 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.

  6. 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.

  7. 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.

  8. Responses of polar mesospheric cloud brightness to stratospheric gravity waves at the South Pole and Rothera, Antarctica

    NASA Astrophysics Data System (ADS)

    Chu, Xinzhao; Yamashita, Chihoko; Espy, Patrick J.; Nott, Graeme J.; Jensen, Eric J.; Liu, Han-Li; Huang, Wentao; Thayer, Jeffrey P.

    2009-03-01

    We present the first observational proof that polar mesospheric cloud (PMC) brightness responds to stratospheric gravity waves (GWs) differently at different latitudes by analyzing the Fe Boltzmann lidar data collected from the South Pole and Rothera (67.5°S, 68.0°W), Antarctica. Stratospheric GW strength is characterized by the root-mean-square (RMS) relative density perturbation in the 30-45 km region and PMC brightness is represented by the total backscatter coefficient (TBC) in austral summer from November to February. The linear correlation coefficient (LCC) between GW strength and PMC brightness is found to be +0.09 with a 42% confidence level at the South Pole and -0.49 with a 98% confidence level at Rothera. If a PMC case potentially affected by a space shuttle exhaust plume is removed from the Rothera dataset, the negative correlation coefficient and confidence level increase to -0.61 and 99%, respectively. The Rothera negative correlation increases when shorter-period waves are included while no change is observed in the South Pole correlation. Therefore, observations show statistically that Rothera PMC brightness is negatively correlated with the stratospheric GW strength but no significant correlation exists at the South Pole. A positive correlation of +0.74 with a confidence level of 99.98% is found within a distinct subset of the South Pole data but the rest of the dataset exhibits a random distribution, possibly indicating different populations of ice particles at the South Pole. Our data show that these two locations have similar GW strength and spectrum in the 30-45 km region during summer. The different responses of PMC brightness to GW perturbations are likely caused by the latitudinal differences in background temperatures in the ice crystal growth region between the PMC altitude and the mesopause. At Rothera, where temperatures in this region are relatively warm and supersaturations are not as large, GW-induced temperature perturbations can

  9. 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

  10. Cips (Cloud Imaging and Particle Size Experiment) Observations of a Newly Discovered Population of Very Large Ice Particles in Polar Mesospheric Clouds

    NASA Astrophysics Data System (ADS)

    Rusch, D. W.; Thomas, G. E.; Chandran, A.; Merkel, A. W.; Lumpe, J. D., Jr.; Randall, C. E.; Olivero, J. J.; Bailey, S. M.; Russell, J. M., III

    2014-12-01

    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 in the size range between 60 and 100 nm (radii of equivalent volume spheres). It is known from lidar, SOFIE, and CIPS measurements that typical mean PMC particle sizes are of the order of 40-50 nm. Determination of particle sizes by CIPS is accomplished by measuring the scattering of solar radiation at various scattering angles at a spatial resolution of 25 km2. PMC with ice particles principally in this 60-100 nm range are observed in 15 to 20 % of all CIPS measurements. These very large particle (VLP) events occur over spatially coherent areas. They are generally associated with regions of low cloud albedo (brightness) and ice water content. We postulate that at least part of this VLP population exists due to the action of long-period gravity waves in the low-temperature summertime mesopause region. We demonstrate the proposed mechanism through use of the 2D Community Aerosol and Radiation Model for Atmospheres (CARMA), which simulates the evolution of ice particles over several cycles of a family of modeled gravity waves. The model results are consistent with a VLP population in the cold troughs of monochromatic gravity waves with horizontal wavelengths of 600 km and periods of 10 hours (Chandran et al., 2013).

  11. Mesospheric mysteries

    SciTech Connect

    Crutzen, P.

    1997-09-26

    Although the chemistry of the upper stratosphere and mesosphere is quite simple with chemical ozone loss reactions being dominated by HOx catalysis, numerous studies have failed to find the expected agreement between odd oxygen production and destruction. This article discusses a solution to this discrepancy and how it relates to the whole understanding of upper atmosphere chemistry and the possibility of an external source of H2O. 10 refs., 1 fig.

  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. 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.

  14. Mesospheric aerosol sampling spectrometer

    NASA Astrophysics Data System (ADS)

    Knappmiller, Scott; Robertson, Scott; Sternovsky, Zoltan; Horanyi, Mihaly; Kohnert, Rick

    . The Mesospheric Aerosol Sampling Spectrometer (MASS) instrument has been launched on two sounding rockets in August, 2007 from Andoya, Norway to detect charged sub-visible aerosol particles in the polar mesosphere. The MASS instrument is designed to collect charged aerosols, cluster ions, and electrons on four pairs of graphite electrodes, three of which are biased with increasing voltage. The design of the MASS instrument was complicated by the short mean free path in the mesosphere. The opening to MASS was deliberately built to increase the mean free path and to reduce the shock wave within the instrument. The design procedure began with aerodynamics simulations of the flow through the instrument using Direct Simulation Monte Carlo (DSMC) in 3-D. The electric fields within the instrument were calculated using a Laplace solver in 3-D. With the aerodynamic and electric field simulations completed, an algorithm was created to find the trajectories of charged aerosols including collisions within MASS. Using this algorithm the collection efficiencies for each electrode was calculated as a function of the charge to mass ratio of the incoming particle. The simulation results have been confirmed experimentally using an Argon RF ion beam. The data from the August launches have been analyzed and the initial results show the MASS instrument operated as expected. Additional studies are underway to determine if there were effects from payload charging or spurious charge generation within the instrument. This project is supported by NASA.

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

    NASA Astrophysics Data System (ADS)

    Ford, George; Newnham, David; Pumphrey, Hugh

    2015-04-01

    We demonstrate the feasibility of stratosphericmesospheric zonal and meridional wind observations using ground-based passive millimetrewave radiometry with lownoise receivers and high-resolution spectrometers. Detailed observations of 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. Measurements in the altitude range 2070 km would fill the 'radar gap' and address the current sparse wind observations for the upper stratosphere and mesosphere that limits our understanding of vertical wave propagation and its impact on planetaryscale circulation. The Atmospheric Radiative Transfer Simulator (ARTS) and Qpack retrieval code is used to retrieve vertical wind profiles from simulations of lineofsight Doppler-shifted atmospheric emission lines above Halley station (75° 37'S, 26° 14'W), Antarctica. The ozone lines centred at 231.28 GHz, 249.79 GHz, and 249.96 GHz and the 230.54 GHz carbon monoxide line are used. The effect of clearsky winter/summer conditions, zenith angle, system temperature (Tsys), and spectrometer frequency resolution on the altitude coverage, measurement uncertainty, and height and time resolution of the retrieved wind profiles is presented. For radiometric observations of Dopplershifted ozone emission lines arising from horizontal winds in the range 1040 m s-1, and with Tsys = 1400 K, we estimate that daily mean zonal and meridional wind profiles covering the altitude range 2575 km with typical measurement uncertainty of 5 m s-1 and vertical resolution of ~12 km could be achieved.

  16. 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. PMID:27635303

  17. 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.

  18. 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

  19. 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

  20. 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.

  1. Uptake of Fe, Na and K atoms on low-temperature ice: implications for metal atom scavenging in the vicinity of polar mesospheric clouds.

    PubMed

    Murray, Benjamin J; Plane, John M C

    2005-12-01

    Ice clouds form in the mesosphere between 80 and 90 km, at high latitudes during summer when the temperature falls below 150 K. There is strong evidence that the water-ice particles in these clouds scavenge metal atoms that are produced in the mesosphere by meteoric ablation. In the present study the uptake of Fe, Na and K on an ice film was studied in a fast flow tube over a temperature range of 80-150 K, covering the temperatures over which ice clouds form in the upper mesosphere. The uptake was found to be highly efficient and mostly in the diffusion-limited regime, requiring accurate measurements of the diffusion coefficients of the metal atoms in He: DFeHe = 366 (+/- 17) (T/296 K)(1.85 +/- 0.07), DNaHe 286 (+/- 13) (T/296 K)(1.68 +/- 0.04) and DKHe = 247 (+/- 15) (T/296 K)(1.69 +/- 0.07) Torr cm2 s(-1). Measured values of the diffusion coefficients in N2 are 112 (+/- 4), 125 (+/- 4) and 88 (+/- 4) Torr cm2 s(-1) at 293 K for Fe, Na and K, respectively. The uptake of Na and K was observed to be extremely efficient from 80-150 K, with lower limits of gamma Na > 0.09 and gamma K > 0.05, although it is likely that gamma is much closer to unity. The uptake of Fe on cubic ice is close to unity efficiency above 135 K, but gamma Fe decreases to only 3 x 10(-3) at 80 K. Uptake of Fe on amorphous ice films is much more efficient than on cubic ice films below 130 K. These results are interpreted using quantum calculations of the metal atoms adsorbed onto a 12-H2O model ice surface. Finally, it is shown that the uptake of Fe, Na and K on low-temperature ice is sufficiently fast to explain the substantial depletions in the mesospheric metal layers that are observed in the presence of mesospheric ice clouds.

  2. Bores In The Mesosphere

    NASA Astrophysics Data System (ADS)

    Smith, S. M.

    Bores are a special type of propagating hydraulic jump. They are a relatively common wave phenomenon in the Earth's oceans, rivers and lower atmosphere but they have been observed only rarely in the mesosphere. We will review the mesospheric bore phenomenon and present wide-field imaging observations of one particularly bright bore event seen at two widely-spaced (500 km) locations in the south-western United States: McDonald Observatory (MDO), Texas and the Starfire Optical Range (SOR), New Mexico. The measurements were supplemented with radar wind measurements, also made at the SOR, and by Na resonance lidar temperature measurements made at Fort Collins, Colorado, approximately 1100 km to the north of MDO. The multi- diagnostic observations provided evidence that mesospheric bores are associated with ducting regions in the mesosphere which allow them to travel distances of over 1500 km and exhibit lifetimes of over 6 hours.

  3. 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).

  4. MAPPING THE DARK MATTER WITH POLARIZED RADIO SURVEYS

    SciTech Connect

    Brown, Michael L.; Battye, Richard A.

    2011-07-01

    In a recent paper, we proposed the use of integrated polarization measurements of background galaxies in radio weak gravitational lensing surveys and investigated the potential impact on the statistical measurement of cosmic shear. Here we extend this idea to reconstruct maps of the projected dark matter distribution or lensing convergence field. The addition of polarization can, in principle, greatly reduce shape noise due to the intrinsic dispersion in galaxy ellipticities. We show that maps reconstructed using this technique in the radio band can be competitive with those derived using standard lensing techniques which make use of many more galaxies. In addition, since the reconstruction noise is uncorrelated between these standard techniques and the polarization technique, their comparison can serve as a powerful check for systematics and their combination can reduce noise further. We examine the convergence reconstruction which could be achieved with two forthcoming facilities: (1) a deep survey, covering 1.75 deg{sup 2} using the e-MERLIN instrument currently being commissioned in the UK and (2) the high-resolution, deep wide-field surveys which will eventually be conducted with the Square Kilometre Array.

  5. Discharges in the Stratosphere and Mesosphere

    NASA Astrophysics Data System (ADS)

    Siingh, Devendraa; Singh, R. P.; Singh, Ashok K.; Kumar, Sanjay; Kulkarni, M. N.; Singh, Abhay K.

    2012-09-01

    In the present paper salient features of discharges in the stratosphere and mesosphere (namely sprites, halos, blue starters, blue jets, gigantic jets and elves), are discussed. The electrostatic field due to charge imbalance during lightning processes may lead to stratospheric/mesospheric discharges either through the conventional breakdown based on streamers and leaders or relativistic runaway mechanism. Most (not all) of the observed features of sprites, halos and jets are explained by this processes. Development and evolution of streamers are based on the local transient electrostatic field and available ambient electron density which dictate better probability in favor of positive cloud-to-ground discharges, and thus explains the polarity asymmetry in triggering sprites and streamers. Elves are generated by electromagnetic pulse radiated by return stroke currents of cloud-to-ground/inter-cloud discharges. Generation of the both donut and pancake shape elves are explained. Electrodynamic features of thunderstorms associated with stratospheric/mesospheric discharges are summarized including current and charge moment associated with relevant cloud-to-ground discharges. The hypothesis relating tropospheric generated gravity waves and mesospheric discharges are also discussed. Finally some interesting problems are listed.

  6. 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

  7. Temperature Deviations in the Midlatitude Mesosphere During Stratospheric Warmings as Measured with Rayleigh-Scatter Lidar

    NASA Astrophysics Data System (ADS)

    Sox, Leda; Wickwar, Vincent; Fish, Chad; Herron, Joshua P.

    2016-06-01

    While mesospheric temperature anomalies associated with Sudden Stratospheric Warmings (SSWs) have been observed extensively in the polar regions, observations of these anomalies at midlatitudes are sparse. The original Rayleigh-scatter lidar that operated at the Atmospheric Lidar Observatory (ALO; 41.7°N, 111.8°W) in the Center for Atmospheric and Space Sciences (CASS) on the campus of Utah State University (USU) collected an extensive set of temperature data for 11 years in the 45-90 km altitude range. This work focuses on the extensive Rayleigh lidar observations made during six major SSW events that occurred between 1993 and 2004, providing a climatological study of the midlatitude mesospheric temperatures during these SSW events. An overall disturbance pattern was observed in the mesospheric temperatures during these SSWs. It included coolings in the upper mesosphere, comparable to those seen in the polar regions during SSW events, and warmings in the lower mesosphere.

  8. Mesospheric cloud formations

    NASA Technical Reports Server (NTRS)

    Forbes, J. M.

    1980-01-01

    Formation of mesospheric clouds as a result of deposition of large amounts of H2O by the heavy lift launch vehicle (HLLV) of the solar power satellite system is discussed. The conditions which must be met in order to form and maintain clouds near the mesopause are described. The frequency and magnitude of H2O injections from the HLLV rocket exhaust are considered.

  9. 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.

  10. 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

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

    PubMed

    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

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

    PubMed

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

    2016-08-12

    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.

  13. 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.

  14. 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

  15. 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.

  16. Gravitomagnetic acceleration of accretion disk matter to polar jets

    NASA Astrophysics Data System (ADS)

    Poirier, John; Mathews, Grant

    2016-03-01

    The motion of the masses of an accretion disk around a black hole creates a general relativistic, gravitomagnetic field (GEM) from the moving matter (be it charged or uncharged) of the accretion disk. This GEM field accelerates moving masses (neutral or charged) near the accretion disk vertically upward and away from the disk, and then inward toward the axis of the disk. As the accelerated material nears the axis with approximately vertical angles, a frame dragging effect contributes to the formation of narrow jets emanating from the poles. This GEM effect is numerically evaluated in the first post Newtonian (1PN) approximation from observable quantities like the mass and velocity of the disk. This GEM force is linear in the total mass of the accretion disk matter and quadratic in the velocity of matter near to the disk with approximately the same velocity. Since these masses and velocities can be quite high in astrophysical contexts, the GEM force, which in other contexts is weak, is quite significant. This GEM effect is compared to the ordinary electromagnetic effects applied to this problem in the past.

  17. 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.

  18. 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

  19. 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

  20. Radiative transfer model for the computation of radiance and polarization in an ocean-atmosphere system: polarization properties of suspended matter for remote sensing.

    PubMed

    Chami, M; Santer, R; Dilligeard, E

    2001-05-20

    A radiative transfer code termed OSOA for the ocean-atmosphere system that is able to predict the total and the polarized signals has been developed. The successive-orders-of-scattering method is used. The air-water interface is modeled as a planar mirror. Four components grouped by their optical properties, pure seawater, phytoplankton, nonchlorophyllose matter, and yellow substances, are included in the water column. Models are validated through comparisons with standard models. The numerical accuracy of the method is better than 2%; high computational efficiency is maintained. The model is used to study the influence of polarization on the detection of suspended matter. Polarizing properties of hydrosols are discussed: phytoplankton cells exhibit weak polarization and small inorganic particles, which are strong backscatterers, contribute appreciably to the polarized signal. Therefore the use of the polarized signal to extract the sediment signature promises good results. Also, polarized radiance could improve characterization of aerosols when open ocean waters are treated.

  1. Radiative Transfer Model for the Computation of Radiance and Polarization in an Ocean -Atmosphere System: Polarization Properties of Suspended Matter for Remote Sensing

    NASA Astrophysics Data System (ADS)

    Chami, Malik; Santer, Richard; Dilligeard, Eric

    2001-05-01

    A radiative transfer code termed OSOA for the ocean -atmosphere system that is able to predict the total and the polarized signals has been developed. The successive-orders-of-scattering method is used. The air -water interface is modeled as a planar mirror. Four components grouped by their optical properties, pure seawater, phytoplankton, nonchlorophyllose matter, and yellow substances, are included in the water column. Models are validated through comparisons with standard models. The numerical accuracy of the method is better than 2%; high computational efficiency is maintained. The model is used to study the influence of polarization on the detection of suspended matter. Polarizing properties of hydrosols are discussed: phytoplankton cells exhibit weak polarization and small inorganic particles, which are strong backscatterers, contribute appreciably to the polarized signal. Therefore the use of the polarized signal to extract the sediment signature promises good results. Also, polarized radiance could improve characterization of aerosols when open ocean waters are treated.

  2. 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

  3. 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

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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

    2016-06-01

    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. PMID:27251280

  9. 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.

  10. 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

    2016-05-23

    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. 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.

  12. 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.

  13. Interhemispheric Dynamical Coupling to the Southern Mesosphere and Lower Thermosphere

    NASA Astrophysics Data System (ADS)

    Murphy, Damian; Alexander, Simon; Vincent, Robert

    The 15-year set of radar observations of Mesosphere and Lower Thermosphere (MLT) winds obtained from Davis station in Antarctica (69S, 78E) provide an opportunity for studies of interhemispheric coupling. Observations and modelling described by Becker and Fritts [2006] suggests that wintertime planetary wave activity, and the gravity wave filtering associated with it, affect the global meridional residual circulation that drives the summer mesosphere from radiative equilibrium. In this context, southern hemisphere stations have the advantage that planetary wave activity of their opposite hemisphere is of greater magnitude making a vari-able response likely. This study uses correlation and superposed epoch analysis, and proposed coupling mechanisms [e.g. Karlsson et al., 2009] to identify atmospheric regions that are po-tentially coupled to the polar MLT. The seasonal variation of that coupling and the influences on that coupling of large scale waves such as the QBO are also investigated. References: Becker, E. and Fritts, D. C., Enhanced gravity-wave activity and interhemispheric coupling during the MACWAVE/MIDAS northern summer program 2002, Ann Geophys, 24, 1175-1188, 2006. Karlsson, B, McLandress, M. and Shepherd, T. G., Inter-hemispheric mesospheric coupling in a comprehensive middle atmosphere model, J. Atmos, Sol-Terr Phys., 71, 518-530, 2009.

  14. 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.

  15. Role of polarity fractions of effluent organic matter in binding and toxicity of silver and copper.

    PubMed

    Yoo, Jisu; Shim, Taeyong; Hur, Jin; Jung, Jinho

    2016-11-01

    This study evaluates the effect of the physicochemical properties of effluent organic matter (EfOM) from industrial and sewage wastewater treatment plants (WWTPs) on the binding and toxicity of Ag and Cu. EfOM was isolated into hydrophobic, transphilic, and hydrophilic fractions depending on its polarity, and was characterized by elemental, specific ultraviolet absorbance, and fluorescence excitation-emission matrix analyses. Our results suggest that the EfOM consists of microbially derived non-humic substances that have lower aromaticity than the Suwannee River natural organic matter (SR-NOM). The Freundlich model was better at explaining the binding of Ag and Cu onto both SR-NOM and EfOM than the Langmuir model. In particular, the hydrophilic fractions of sewage EfOM showed higher binding capacities and affinities for Ag and Cu than the corresponding hydrophobic fractions, resulting in better reduction of the acute toxicity of Ag and Cu towards Daphnia magna. However, in the case of both SR-NOM and industrial EfOM, the hydrophobic fractions were more efficient at reducing metal toxicity. These findings suggest that the EfOM has different physicochemical properties compared with NOM and that the binding and toxicity of heavy metals are largely dependent on the polarity fractions of EfOM. PMID:27318731

  16. 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. PMID:21875673

  17. 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.

  18. 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.

  19. Measurements of Mesosphere and Lower Thermosphere Winds by the TIMED Doppler Interferometer

    NASA Astrophysics Data System (ADS)

    Killeen, T. L.; Gablehouse, R. D.; Johnson, R. M.; Wu, Q.; Solomon, S. C.; Gell, D. A.; Niciejewski, R. J.; Skinner, W. R.; Kafkalidis, J. F.; Ortland, D. A.

    2002-12-01

    Since the launch of the NASA Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite in December 2001, the TIMED Doppler Interferometer (TIDI) has been measuring the global wind field in the mesosphere and lower thermosphere. Validation of these data using ground-based and other space-based observations is in progress. Early analyses have focused on wind measurements in the 60 to 110 km altitude region using emissions from the O2 Atmospheric (0-0) band. We will present results showing the variability of tidal oscillations in the middle atmosphere, and new measurements of polar mesopause dynamics.

  20. Missing driver in the Sun-Earth connection from energetic electron precipitation impacts mesospheric ozone.

    PubMed

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

    2014-10-14

    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.

  1. 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

  2. The Tromsø programme of in situ and sample return studies of mesospheric nanoparticles

    NASA Astrophysics Data System (ADS)

    Havnes, O.; Antonsen, T.; Hartquist, T. W.; Fredriksen, Å.; Plane, J. M. C.

    2015-05-01

    We review some of the work performed over the past two decades with rocket-borne detectors to study mesospheric dust or nanoparticles, including meteoric smoke particles (MSPs) and water ice particles in the mesosphere. We focus on regions in which noctilucent clouds (NLCs) and polar summer mesospheric echoes (PMSEs) occur. Our primary emphasis is on several detectors designed, built and used by the Tromsø group and collaborators, and results obtained with them. These include the DUSTY, MUDD and ICON probes, the latter for which the results of laboratory tests are presented. However, we also mention, but do not address in detail, some of the investigations conducted by others and describe very briefly our preparations for sample return measurements. We consider the importance of accounting for the secondary charging occurring in detectors as nanoparticles strike them, evidence that MSPs fill up to several per cent of the volume in icy particles and measurements of the size distribution of the MSPs.

  3. Missing driver in the Sun-Earth connection from energetic electron precipitation impacts mesospheric ozone.

    PubMed

    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

  4. 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.

  5. 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.

  6. 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

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

    NASA Technical Reports Server (NTRS)

    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.

    1988-01-01

    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.

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

    PubMed

    Sulzberger, Barbara; Arey, J Samuel

    2016-07-01

    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.

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

    PubMed

    Sulzberger, Barbara; Arey, J Samuel

    2016-07-01

    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. PMID:27110903

  10. 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.

  11. 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.

  12. The influence of the residual circulation on hemispheric differences in the mesosphere

    NASA Astrophysics Data System (ADS)

    karlsson, B.

    2012-12-01

    The residual circulation in the middle atmosphere has a large impact on the temperature field in the mesosphere. Due to its upward motion at high latitudes in the summer hemisphere, this region is driven towards extremely low temperatures through adiabatic cooling. At the same time, the temperature is well above radiative equilibrium in the winter lower mesosphere, due to down welling and adiabatic heating. This gravity wave driven circulation also supplies the summer mesosphere with water vapor from the lower atmosphere and transports particles from one part of the globe to another. Intriguingly, it is the dynamics in the winter high latitude troposphere and stratosphere that determine the strength of this circulation, even in the summer polar mesopause region. Noctilucent clouds (NLC), which can be thought of as a visible part of this pole-to-pole circulation, can teach us more about how the middle atmosphere behaves. The onset of these mesospheric clouds is affected by the persistence of the winter polar vortex in the same hemisphere as the clouds (intra-hemispheric coupling), whereas the mid-seasonal variability is driven by the stratospheric winter conditions in the opposite hemisphere (inter-hemispheric coupling). In this presentation, the consequences of these coupling processes will be discussed in terms of hemispheric differences observed in the NLC.

  13. Exposure to Atmospheric Particulate Matter Enhances Th17 Polarization through the Aryl Hydrocarbon Receptor

    PubMed Central

    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. PMID:24349309

  14. 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.

  15. 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.

  16. Seasonal ozone variations in the upper mesosphere

    SciTech Connect

    Thomas, R.J. )

    1990-05-20

    The global daytime ozone was measured by the Solar Mesosphere Explorer satellite (SME) for 5 years. The measurements extend through the mesosphere, covering from 50 km to over 90 km. The ozone in the upper mesosphere varies annually by up to a factor of 3. The observed seasonal variations may be summarized in several different ways. From year to year there is a great deal of repeatability of these variations. This repeatability occurs in most of the upper mesosphere outside the tropics. Near 0.01 mbar (80 km) the mid- and high-latitude mixing ratio peaks each year in mid-April. A secondary maximum in the altitude profile of ozone density usually occurs near 85 km. Changes in this structure are directly related to the April maximum and other seasonal changes seen at 0.01 mbar. The changing seasonal structure produces a bump at the ozone mixing ratio minimum that is largest just after spring equinox. This perturbation to the mixing ratio profile seems to move upward during the first half of the year. The seasonal changes of ozone were analyzed in terms of annual and semiannual structure. The variations generally have both an annual and semiannual component depending on altitude and latitude. The phases of the variations change quickly with both altitude and latitude. The semiannual component peaks in April, over most of the upper mesosphere.

  17. Decadal variability in PMCs and implications for changing temperature and water vapor in the upper mesosphere

    NASA Astrophysics Data System (ADS)

    Hervig, Mark E.; Berger, Uwe; Siskind, David E.

    2016-03-01

    Observations of polar mesospheric clouds (PMC) from the solar backscatter ultraviolet (SBUV) satellite instruments are used to characterize variability and trends from 1979 to 2014. The SBUV PMC record indicates decadal oscillations during the 1980s and 1990s, 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 1980s and 1990s 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 toward 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. SBUV indicates cooling trends that increase toward higher latitudes (-0.5 ± 0.2 K decade-1 at 77°N), consistent with the MIMAS model and scant observations. SBUV indicates increasing water vapor in the Northern Hemisphere upper mesosphere (0.07 ± 0.03 ppmv decade-1 at 77°N, insignificant in the Southern Hemisphere), with values that are consistent with MIMAS but less than expected due to increasing methane.

  18. 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.

  19. Observational and modelling study of mesospheric bores

    NASA Astrophysics Data System (ADS)

    Loughmiller, P. J.; Kelley, M. C.; Hickey, M. P.

    In studies of the dynamics of the upper atmosphere some of the most intriguing mesospheric phenomena observed high over the Hawaiian night skies are wall waves and internal bores These events are documented in airglow images taken by high performance all-sky CCD imaging systems operating on top of Haleakala Crater as part of the ongoing collaborative Maui - Mesosphere and Lower Thermosphere MALT campaign jointly sponsored by the National Science Foundation and the Air Force Office of Scientific Research Bolstered by the Maui-MALT dataset several theories now exist for mesospheric bores agreeing in principle that they are likely nonlinear structures spawned by gravity waves and propagating within a thermal inversion layer A new investigation will model optical emissions using a robust time-dependent chemical dynamics model to explore the airglow response to ducted gravity waves and in turn the geographical and vertical coupling relationships which may exist

  20. 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.

  1. 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.

  2. Temperature, ozone, and nitric oxide experiment (TONE) for the thermosphere-ionosphere-mesosphere energetics and dynamics (TIMED) mission

    SciTech Connect

    Rusch, D.W.; Barth, C.A.; Clancy, R.T.

    1994-12-31

    The Temperature-Ozone-Nitric Oxide Experiment (TONE) on the Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics (TIMED) mission consists of two ultraviolet spectrometers and an infrared photometer. A Medium Resolution Spectrometer (MRS) covers the spectral region from 210 to 247 nm with 0.2 nm resolution, and a Low Resolution Spectrometer/Infrared Photometer (LRS/IRP) covers the 235 to 320 mn region with 2.0 nm resolution, and measures the 1.27 micron emission from molecular oxygen excited by ozone photolysis. The Earth`s limb is scanned by articulation mirrors which also serve as the field-of-view limiting elements. The TONE measures profiles of emission as a function of altitude on the Earth`s limb. The primary measurements include profiles of Rayleigh scattered sunlight and 1.27 micron emission in the mesosphere and lower thermosphere, and fluorescent emission from nitric oxide in the upper mesosphere and thermosphere. The inverted radiance measurements will yield profiles of temperature, density, and ozone in the mesosphere, and temperature and nitric oxide density in the thermosphere with 2.5 km vertical resolution and 4.5 degree spatial resolution along the orbital path. The primary TONE measurements extend from 50 to 180 km and are fundamental to the science objectives of the TIMED mission. The broad capabilities of the TONE contribute significantly to the TIMED mission with a low-cost, highly reliable instrument based on a long heritage of space instruments built at the University of Colorado`s Laboratory for Atmospheric and Space Physics. The TONE has heritage from spectrometers on Mariner 9, Pioneer Venus, the Solar Mesosphere Explorer, Galileo, and Cassini. Keywords: thermosphere, mesosphere, ozone, global change, nitric oxide, temperature, ultraviolet spectrometer, remote sensing, limb scanning, polar mesospheric clouds.

  3. Illumination of mesospheric irregularity by lightning discharge

    NASA Astrophysics Data System (ADS)

    Füllekrug, Martin; Mezentsev, Andrew; Soula, Serge; Velde, Oscar; Evans, Adrian

    2013-12-01

    Theoretical model calculations recently predicted the existence of mesospheric irregularities which assist the initiation of sprites. Here we report the experimental detection of a ˜3-19 km3 large mesospheric irregularity at ˜80-85 km height which is illuminated by the electromagnetic field of an intense positive cloud-to-ground lightning discharge. While the lightning discharge causes a prompt group of four sprites above the lightning discharge, the mesospheric irregularity is found at a horizontal distance at least ˜15-20 km away from the sprite group and it rebrightens ˜40-60 ms after the sprite group occurrence. This rebrightening is driven by a local quasi-static electric field enhancement with a charge moment ˜4-20 Ckm which causes the irregularity to develop a downward descending luminous column from ˜75-85 km height. The quasi-static electric field enhancement is caused by the reorganization of residual charge inside the thundercloud during a high-level activity of intracloud discharges with ˜10-20 pulses per ms. Such mesospheric irregularities might have an effect on the wave propagation of 100 kHz radio waves which are used for atomic time transfer and marine navigation.

  4. 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

  5. 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.

  6. Sprite streamer initiation from natural mesospheric structures.

    PubMed

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

    2015-01-01

    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. PMID:26118893

  7. Sprite streamer initiation from natural mesospheric structures

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    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.

  8. Possible seasonal variability of mesospheric water vapor

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    Ground-based spectral line measurements of the 22.2 GHz water vapor line in atmospheric emission were made at the Jet Propulsion Laboratory, which have been used to deduce the mesospheric water vapor profile. The measurements were made nearly continuously in the spring and early summer of 1984. The results indicate a temporal increase in the water vapor mixing ratio in the upper mesosphere from April through June. At 75 km, this increase is nearly by a factor of 2. Comparison of the present results with the results of a similar series of measurements made at the Haystack (radio astronomy) Observatory indicate that this temporal increase is part of a seasonal variation.

  9. A mesospheric source of nitrous oxide

    NASA Technical Reports Server (NTRS)

    Zipf, E. C.; Prasad, S. S.

    1982-01-01

    In the terrestrial atmosphere, nitrous oxide (N2O) has a major role in the chemistry of ozone. Current atmospheric models assume that N2O is produced only by fixation at the earth's surface and that there are no local sources in the stratosphere or mesosphere. It is pointed out here that a significant in situ N2O source does exist above 20 km due to the excitation of the metastable N2(A 3Sigma u +) state by resonance absorption of solar UV photons that penetrate deeply into the atmosphere through the 1,800-2,200 A O2-O3 window. This source significantly affects the NO altitude distribution in the mesosphere and, in the earth's prebiological atmosphere, made N2O an important stratospheric constituent.

  10. Minor constituents in the stratosphere and mesosphere

    NASA Technical Reports Server (NTRS)

    Hudson, R. D.

    1979-01-01

    A review of the research in minor constituents in the stratosphere and mesosphere, carried out between 1975 and 1978, is presented. Much of the theoretical research was done with the aid of one-dimensional models. Different aspects of these models are discussed. Measurements of the chlorofluoromethanes, hydrochloric acid, nitric oxide, nitrous oxide, and hydrogen oxide were conducted. It is noted that the hydrogen oxides are now assuming a larger role in stratospheric photochemistry than have been postulated before. The effect of water vapor and the hydrogen oxides on the overall chemistry of the stratosphere was investigated theoretically, along with the possible relationship between solar activity and atmospheric ozone. The mesosphere study included ozone, water vapor, nitric oxide, and odd nitrogen investigations.

  11. 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.

  12. 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. PMID:26479146

  13. 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).

  14. Total quality management: a matter of quality polarity analysis and management.

    PubMed

    Hurst, J; Keenan, M; Sipp, R

    1993-03-01

    Alvin Zander claims that group members are often more concerned with personal needs and rights than those of the organization. People tend to have their attention on only half (the upside of their preferred pole and the downside of the other) of the whole "picture" of a polarity. By making a complete, accurate diagram of the entire polarity and continually updating and using it, people can promote collaboration and effectiveness despite the automatic tendency for people to be both blind to the entire situation and individualistically undermining successful management of the polarity over time. In other words, most efforts to produce noteworthy and lasting results in successful implementation of total quality management most likely will be limited--or result in failure--due to the fact that nursing managers, staff, and administrators view autocratic management and employee empowerment as separate choices to be made and are unclear that their day-to-day action impacts both direction and empowerment continually. Polarity analysis and management tend to integrate what appear to be personal and individual needs with those of others in a collaborative partnership. When addressing any polarity, it is important to acknowledge that people at all levels of the organization potentially are paradoxically the greatest resources and the biggest barriers to unprecedented breakthrough results. Overzealous action to reduce autocratic leadership will subsequently affect empowerment negatively and thus ultimately erode direction. Likewise overzealous action to increase empowerment will promote a lack of focus and finally erode organization and compliance. As any group of people begins to experience the recurrence of the ups and downs of both poles, there is increased frustration, resignation, and sense of ineffectiveness.

  15. 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.

  16. Measurements of mesospheric aerosol particles during the ECOMA/MASS campaign 2007.

    NASA Astrophysics Data System (ADS)

    Strelnikova, Irina; Rapp, Markus; Strelnikov, Boris; Latteck, Ralph; Baumgarten, Gerd; Brattli, Alvin; Friedrich, Martin; Gumbel, Jorg; Robertson, Scott

    In August 2007 the joint European-American ECOMA/MASS (Existence and Charge state Of Meteoric smoke particles in the middle Atmosphere/Dust MASS Analyzer) sounding rocket and ground-based campaign took place at the Andøya Rocket Range (ARR) (69° N). This campaign was devoted to the investigation of mesospheric aerosol particles. During this campaign, three instrumented sounding rockets were launched under the PMSE and NLC conditions. All rockets were carrying instruments to characterize mesospheric aerosol particles and their environment. The ECOMA rocket was launched during the first salvo shortly (30 min) after the MASS payload. At that time, the EISCAT (69° N, 19° E) VHF and ALWIN radars observed a double layered PMSE. Also an NLC layer was detected by lidar and photometers onboard each rocket. The main instrument of the ECOMA payload is the "ECOMA particle detector". This instrument comprises a classical Faraday cup with a xenon-flash lamp for the active photoionization/photodetachment of mesospheric smoke particles (MSPs) and the subsequent detection of corresponding photoelectrons. Comparing direct Faraday cup measurements and photocurrents we are able to derive particle properties like number densities and particle radii. We present the results of these measurements that show the presence of aerosol particles inside the NLC and PMSE layer, but not below or above these layers. These results are consistent with model predictions, which account for global transport of meteoric smoke. This implies that ice nucleation in the polar summer needs to be reconsidered.

  17. 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.

  18. Gravitomagnetic Acceleration of Black Hole Accretion Disk Matter to Polar Jets

    NASA Astrophysics Data System (ADS)

    Poirier, John; Mathews, Grant

    2015-04-01

    It is shown that the motion of the neutral masses in an accretion disk orbiting a black hole creates a magnetic-like (gravitomagnetic) field that vertically accelerates neutral particles near the accretion disk away from the disk and then inward toward the axis of the accretion disk. Moreover, as the accelerated material nears the axis, a frame-dragging effect twists the trajectories around the axis thus contributing to the formation of a narrow polar jet emanating from the poles.

  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. SCIAMACHY long-term observations of nitric oxide in the mesosphere and lower thermosphere

    NASA Astrophysics Data System (ADS)

    Bender, Stefan; Urban, Joachim; Funke, Bernd; Lopez-Puertas, Manuel; Perot, Kristell; Sinnhuber, Miriam; Langowski, Martin; Burrows, John

    Charged particles from the solar wind produce nitric monoxide (NO) in the upper atmosphere in a number of ways. Precipitating auroral electrons produce NO in the lower thermosphere within the auroral oval. Relativistic electrons from the radiation belts may also produce NOx in the mesosphere and upper stratosphere, though there is few observational evidence so far. On the other hand, also UV photoionisation produces NO in the lower thermosphere. In polar regions, NOx from the upper atmosphere can be transported down to the stratosphere during polar winter. After reaching the stratosphere, NO then destroys ozone in catalytic cycles. Ozone contributes substantially to the radiative heating and cooling of the stratosphere. Therefore, its reduction by NO links geomagnetic activity to atmospheric dynamics, possibly down to the surface. We use SCIAMACHY data from the special MLT mode (50 km to 150 km, 2008--2012) and nominal limb scans (up to 90 km, 2002--2012) to examine the impact of solar activity on NO production. We carry out a multi-linear regression analysis considering annual, semi-annual, geomagnetic, and solar variability for both data sets. The coefficents are compared to the results of the same analysis from MIPAS and Odin/SMR NO data. We find that the NO number densities correlate clearly with solar UV variability in the lower thermosphere (100--110 km) at all latitudes. This correlation indicates NO production via photoionisation at these altitudes. We also observe a response to geomagnetic activity at high latitudes from the lower thermosphere down to the lower mesosphere. This response apparently signifies both downwelling of NO during polar winter, and a direct impact of particles not only in the auroral region but also in the mesosphere (~ 80 km).

  1. Unusual Mesospheric Bore Event Observed Over Antarctica

    NASA Astrophysics Data System (ADS)

    Taylor, M. J.; Nielsen, K.; Stockwell, R.; Picard, R. H.; Jarvis, M.

    All-sky CCD observations of mesospheric gravity waves have been made from Halley Station Antarctica (75.5 S, 26.7 W) as part of a collaborative research program between British Antarctic Survey, U.K. and Utah State University, USA. One goal of this investigation is the determination of the characteristics and sources of short-period (< 1 hour) gravity waves observed during the Antarctic winter in the absence of local tropospheric convection. This report describes an unusual mesospheric ``bore'' event that was observed near-simultaneously in three nightglow emissions: the OH (˜ 87 km), O2(0,1) (˜ 94 km) and Na (589.2 nm) (˜ 90 km), over a period of ˜ 3 hours on the 27-28 May, 2001. Mesospheric bores are rare wave events that have previously only been reported at low- and mid latitudes. This Antarctic event is particularly interesting for several reasons, (a) it was characterized by an extensive, high contrast linear wave front that rotated significantly in azimuth as it passed overhead, (b) the associated wave train was observed to grow in the number of crests, consistent with that expected for a ducted, bore-like motion, (c) the individual wave crests exhibited a spatially localized acceleration, possibly due to a sudden change in depth of the duct, and (d) the primary direction of motion of the event was due southwards towards the Antarctic pole suggesting exceptionally long range wave propagation from potential tropospheric sources close to Africa. The evolution and characteristics of this remarkable wave event will be presented together with a discussion of its possible origin.

  2. Isolating Stratospheric Warmings -- Mesosphere to Troposphere

    NASA Astrophysics Data System (ADS)

    Coughlin, K.

    Stratospheric Warming events exhibit the most drastic changes seen in the stratosphere and yet the categorization of these events continues to be adhoc Understandably the definitions of major warming minor warmings and or Canadian warmings often depend on the scientific problem at hand And yet we show here that these events are statistically separated from the rest of the days in the winter stratosphere We show how warmings can be isolated and defined in a objective manner Furthermore we are then able to show the effect of these warmings from the mesosphere down to the troposphere

  3. Radiative energy balance of the Venus mesosphere

    NASA Astrophysics Data System (ADS)

    Haus, R.; Goering, H.

    1990-03-01

    An accurate radiative transfer model for line-by-line gaseous absorption, as well as for cloud absorption and multiple scattering, is used in the present calculation of solar heating and thermal cooling rates for standard temperature profiles and temperatures yielded by the Venera 15 Fourier Spectrometer Experiment. A strong dependency is noted for heating and cooling rates on cloud-structure variations. The Venus mesosphere is characterized by main cloud-cover heating and overlying-haze cooling. These results are applicable to Venus atmosphere dynamical models.

  4. 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.

  5. Radiative energy balance of the Venus mesosphere

    SciTech Connect

    Haus, R.; Goering, H. )

    1990-03-01

    An accurate radiative transfer model for line-by-line gaseous absorption, as well as for cloud absorption and multiple scattering, is used in the present calculation of solar heating and thermal cooling rates for standard temperature profiles and temperatures yielded by the Venera 15 Fourier Spectrometer Experiment. A strong dependency is noted for heating and cooling rates on cloud-structure variations. The Venus mesosphere is characterized by main cloud-cover heating and overlying-haze cooling. These results are applicable to Venus atmosphere dynamical models. 24 refs.

  6. Possible effect of hyperthermal electrons on the charging of mesospheric dust

    NASA Astrophysics Data System (ADS)

    Rosenberg, M.; Varney, R. H.; Kelley, M. C.; Paschall, D.

    2012-01-01

    It is generally assumed that negatively charged icy dust particles in the mesosphere are charged by the collection of thermal plasma particles. However, there are some indications that there may be a population of hyperthermal electrons in the D-region under auroral activity under certain conditions (e.g. Margot-Chaker and McNamara, Planetary and Space Science 32, 391, 1984). In this brief communication, we speculate on the effect of a hyperthermal distribution of electrons on dust charging, and how this might affect prevailing turbulence scattering theory for polar summer mesophere echoes.

  7. Proposed geomagnetic control of semiannual waves in the mesospheric zonal wind

    NASA Technical Reports Server (NTRS)

    Belmont, A. D.; Nastrom, G. D.; Mayr, H. G.

    1975-01-01

    The polar semiannual oscillation in zonal wind explains midwinter weakening of the polar vortex and the relatively short stratospheric and mesospheric summer easterlies. The phase of the wind oscillation is equinoctial, as is the phase of the semiannual component in magnetic storm activity. For a given altitude, the contours of amplitude of the semiannual wind oscillation have less variability in geomagnetic than in geographic coordinates. It is suggested that the polar wind oscillations are caused by the semiannual maxima in magnetic storm activity, which lead to electron dissociation of O2 into O, in turn increasing ozone more rapidly than the dissociation of N2 destroys ozone, and inducing a semiannual variation in the thermal and wind fields. This implies that geomagnetic processes may cause or affect the development of sudden warmings. As the tropical semiannual wind oscillation is symmetric about the geomagnetic equator, the same processes may also influence the location of the tropical wind wave.

  8. 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.

  9. 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

  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. 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.

  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. Using Sun Spikes to Measure Mesospheric Conductivity

    NASA Astrophysics Data System (ADS)

    Shimogawa, M. R.; Holzworth, R. H.

    2005-12-01

    Our payload was designed to study the electrodynamics of noctilucent clouds (NLCs) using double Langmuir probes. Sun spikes in the probe voltage, which occur naturally when a probe is shadowed by the rocket body, were two to three times larger when the rocket was above the NLC than when below it, on both the upleg and downleg portions of the flight. In the low conductivity found below the NLC, the sun spikes did not saturate, so a rough conductivity measurement could be made using these sun spike data. We found the conductivity to be about 8×10-10>S/m at 80 km altitude, which is in agreement with measurements made of the positive ion conductivity during the flight. This is effectively the same as the relaxation method for measuring conductivity in the lower atmosphere, shown here to work in the mesosphere.

  15. 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.

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

    PubMed

    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

    2015-03-01

    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

  17. 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

  18. In-Situ Evidence for a Strong Seasonal Variability of Meteor Smoke at High Northern Latitudes and Implications for Mesospheric ice Nucleation

    NASA Astrophysics Data System (ADS)

    Rapp, M.; Strelnikova, I.; Strelnikov, B.; Baumgarten, G.; Gumbel, J.; Megner, L.; Friedrich, M.; Hoppe, U.; Robertson, S.; Knappmiller, S.; Sternovsky, Z.; Wolff, M.

    2008-12-01

    We report on new in situ measurements of meteor smoke particles (MSPs) and their mesospheric environment from three international field campaigns at the North-Norwegian Andoya Rocket Range. These are the ECOMA campaigns in 2006 and 2008 and the joint ECOMA/MASS campaign in 2007. During these campaigns a total of 6 sounding rockets were successfully launched. The prime instrument of the ECOMA- payload is a detector making use of active photoionization of MSPs and the subsequent detection of corresponding photoelectrons. During the first flight in September 2006, MSPs were detected throughout the mesosphere with concentrations in reasonable agreement with predictions from microphysical models. All later flights with this detector under polar summer conditions, however, do not show any detectable MSP concentration at altitudes below ~75 km, whereas the detector did detect signatures of mesospheric ice particles at about 83 km during all flights. In each of these cases, the mesospheric ice detection is unequivocally confirmed by simultaneous photometer measurements of noctilucent cloud particles on the same rocket payloads. Also, the electrostatic mass spectrometer for nanometer-sized charged aerosol particles MASS which was launched close to the ECOMA-rocket in 2007 did not detect any particle signatures outside the mesospheric ice region. We critically discuss these observations in the context of MSP- and ice particle-microphysics of the mesosphere using simultaneous measurements of the ambient plasma from the same sounding rockets as well as satellite observations of nitric oxide from the Canadian ACE satellite. Taking further into account high resolution temperature measurements from each rocket payload, we tentatively draw conclusions on the feasibility of different potential nucleation pathways such as heterogeneous nucleation on neutral and/or charged MSPs, ionic nucleation, and homogeneous nucleation in the presence of pronounced temperature fluctuations owing

  19. 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

  20. 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.

  1. a Measurement of Hydroxyl in the Daytime Mesosphere.

    NASA Astrophysics Data System (ADS)

    Cageao, Richard Philip

    Hydroxyl is a very reactive free radical which dominates the odd-hydrogen - odd-oxygen reaction chemistry in the earth's mesosphere. The objective of this thesis was the development of an instrument which would measure the concentration of hydroxyl in the mesosphere and an assessment, based on this data, of the current understanding of mesospheric chemistry. A new instrument, a coupled Ebert-Fastie spectrometer and Fabry-Perot interferometer (UV-FPI), was developed to measure spectroscopically the ultraviolet solar resonance fluorescence emission of hydroxyl. The instrument was designed to observe these emissions in the near-ultraviolet at 3087 A against the bright background of Rayleigh scattered sunlight. The background was suppressed by the high resolution Fabry-Perot interferometer operating over the narrow wavelength region defined by the Ebert -Fastie spectrometer bandpass. The remote measurement of hydroxyl was made from a sounding rocket platform with the instrument viewing the earth's limb for the maximum integrated path length of hydroxyl emission. The sounding rocket payload also carried instruments which made simultaneous in situ and remote sensing measurements of atomic oxygen and temperature, respectively. Although the UV-FPI configuration was not optimum for measurement of the desired hydroxyl emission, upper limits could be set on the hydroxyl concentrations. The hydroxyl concentration inferred from the emission measurements was 50% lower than a previous measurement. Comparison of this result and the data for mesospheric abundances of ozone and atomic oxygen with current chemical models shows that modeled odd-hydrogen activity in the middle mesosphere must be reduced and vertical advection in the upper mesosphere must be increased in order to successfully model the chemical processes occurring in the mesosphere.

  2. Mesospheric ozone measurements by SAGE II

    NASA Astrophysics Data System (ADS)

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

    1994-04-01

    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.

  3. 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.

  4. 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.

  5. Inter-hemispheric Comparison of Mesospheric Short-period Gravity Wave Propagation

    NASA Astrophysics Data System (ADS)

    Nielsen, K.; Taylor, M. J.; Collins, R. L.; Irving, B. K.; Negale, M.; Siskind, D. E.; Eckermann, S. D.; Hoppel, K.; Harvey, V.; Russell, J. M.

    2011-12-01

    Mesospheric short-period (≤1-hr) gravity waves are of great importance for dynamics in the mesosphere-lower thermosphere (MLT) region, and are typically measured by instruments capable of high temporal and/or spatial resolutions such as lidars and airglow imagers. These waves have been studied extensively at low- and mid-latitudes where known wave sources are well established. The results show strong dependence on the background wind and temperature fields, which can act as a barrier prohibiting vertical propagation of the waves, as well as providing a ducted environment in which the waves can travel large horizontal distances. In fact, results show that up to 75% of these waves may exhibit ducted wave motion. Recent airglow imaging measurements over Antarctica have revealed a large number of short-period gravity waves in absence of the prominent wave sources present at lower latitudes. In contrast to results at lower latitudes, very few waves (˜5%) observed over Halley (76°S) exhibited Doppler ducted motion. In this work, we utilize airglow imagery, SABER temperature measurements, together with the Navy's high-altitude numerical weather prediction system, NOGAPS-ALPHA, to investigate propagation conditions (particularly, the role of thermal ducting) over Rothera (68°S). Data acquired from a newly installed airglow imager operating at Poker Flat, Alaska (65°N) and the co-located lidar provide an opportunity to perform an inter-hemispheric comparison of propagation conditions over two polar sites at similar latitudes.

  6. 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.

  7. The response of mesospheric NO to geomagnetic forcing in 2002-2012 as seen by SCIAMACHY

    NASA Astrophysics Data System (ADS)

    Sinnhuber, M.; Friederich, F.; Bender, S.; Burrows, J. P.

    2016-04-01

    Daily NO number density, retrieved from measurements of the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) from 2002 to 2012 for polar summer in the mesosphere, is used to investigate the response of NO to geomagnetic activity, as expressed by the auroral electrojet (AE) index. Applying the superposed epoch analysis, we observe a clear response of NO to strong geomagnetic forcing at geomagnetic latitudes 55-75°N/S and altitudes above 66 km. The 27 day solar rotation cycle is observed, indicating that some of the observed geomagnetic events are related to solar coronal holes. We find a linear relationship between anomalies of AE and NO at geomagnetic latitudes 55-70°N/S and 70-74 km altitude. A clear auroral oval-like structure is observed on days of strong geomagnetic forcing in both hemispheres, with small longitudinal inhomogeneities, which might be related to the South Atlantic Anomaly or the magnetic local time. The NO lifetime and production rate per AE anomaly has been derived from a least squares fit to the observations. Comparisons of results from a simple model using this empirical NO production and a lifetime varying from 1.2 days in summer to 10 days in winter to SCIAMACHY observations show good agreement. In particular, the strength and interannual variability of the wintertime maximum is well captured. This suggests that direct production of NO in the upper mesosphere above 72 km contributes substantially to the so-called energetic particle precipitation indirect effect.

  8. 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. PMID:25321674

  9. 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.

  10. Revised correlation between Odin/OSIRIS PMC properties and coincident TIMED/SABER mesospheric temperatures

    NASA Astrophysics Data System (ADS)

    Feofilov, A.; Petelina, S. V.; Kutepov, A. A.; Pesnell, W. D.; Goldberg, R. A.; Llewellyn, E. J.; Russell, J. M.

    2006-12-01

    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 coincidence identified within ±1 degree latitude, ±2 degrees longitude and ≤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, actually located at higher (and colder) altitudes are detected at lower altitudes. S.V. Petelina, D.A. Degenstein, E.J. Llewellyn, N.D. Lloyd, C.J. Mertens, M.G. Mlynczak, and J.M. Russell III, "Thermal conditions for PMC existence derived from Odin/OSIRIS and TIMED/SABER data", Geophys. Res. Lett., 32, L

  11. 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.

  12. SMILES observations of mesospheric ozone during the solar eclipse

    NASA Astrophysics Data System (ADS)

    Imai, Koji; Imamura, Takashi; Takahashi, Kenshi; Akiyoshi, Hideharu; Yamashita, Yousuke; Suzuki, Makoto; Ebisawa, Ken; Shiotani, Masato

    2015-05-01

    The Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) successfully observed vertical distributions of ozone (O3) concentration in the middle atmosphere during the annular solar eclipse that occurred on 15 January 2010. In the mesosphere, where the photochemical lifetime of O3 is relatively short (approximately 100 s), altitude-dependent changes in O3 concentration under reduced solar radiation and their temporal variations were clearly observed as a function of the eclipse obscuration. This study reports the vertical distributions of mesospheric O3 during a solar eclipse event and analyzes theoretically the eclipse-induced changes. We show that simple analytical expressions for O3 concentration, which assume that O3 and O are in a photochemically steady state, can be used to describe the O3 concentration under reduced solar radiation. The SMILES data obtained during the eclipse provide a unique opportunity to test our current understanding of mesospheric O3 photochemistry.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. Long term variations and solar variability of atomic oxygen and hydrogen in the mesosphere / lower thermosphere

    NASA Astrophysics Data System (ADS)

    Ern, Manfred; Kaufmann, Martin; Lehmann, Catrin; Riese, Martin; Smith, Anne; Marsh, Daniel

    Global measurements of the hydroxyl mesospheric airglow as observed by the SCIAMACHY satellite instrument are presented. SCIAMACHY is mounted on ESA's Envisat launched in March 2002 into a polar, sun-synchronous orbit with an inclination of 98.7deg and an ascending node at 22:00 local solar time. Limb observations on the night side cover about 70 degrees in terms of latitude during each orbit, covering 30S-70N, depending on season. Based on these measurements altitude profiles of atomic oxygen and hydrogen are retrieved by means of an OH non-LTE model. These data are analyzed with respect to solar illumination conditions and global wave activity. A windowed space-time Fourier analysis is carried out to investigate seasonal changes in mesopause wave activity. First comparisons with simulations of the NCAR ROSE model are shown.

  18. 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.

  19. 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.

  20. 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.

  1. Validation of the global distribution of CO2 volume mixing ratio in the mesosphere and lower thermosphere from SABER

    NASA Astrophysics Data System (ADS)

    Rezac, L.; Jian, Y.; Yue, J.; Russell, J. M.; Kutepov, A.; Garcia, R.; Walker, K.; Bernath, P.

    2015-12-01

    The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite has been measuring the limb radiance in 10 broadband infrared channels over the altitude range from ~ 400 km to the Earth's surface since 2002. The kinetic temperatures and CO2 volume mixing ratios (VMRs) in the mesosphere and lower thermosphere have been simultaneously retrieved using SABER limb radiances at 15 and 4.3 µm under nonlocal thermodynamic equilibrium (non-LTE) conditions. This paper presents results of a validation study of the SABER CO2 VMRs obtained with a two-channel, self-consistent temperature/CO2 retrieval algorithm. Results are based on comparisons with coincident CO2 measurements made by the Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) and simulations using the Specified Dynamics version of the Whole Atmosphere Community Climate Model (SD-WACCM). The SABER CO2 VMRs are in agreement with ACE-FTS observations within reported systematic uncertainties from 65 to 110 km. The annual average SABER CO2 VMR falls off from a well-mixed value above ~80 km. Latitudinal and seasonal variations of CO2 VMRs are substantial. SABER observations and the SD-WACCM simulations are in overall agreement for CO2 seasonal variations, as well as global distributions in the mesosphere and lower thermosphere. Not surprisingly, the CO2 seasonal variation is shown to be driven by the general circulation, converging in the summer polar mesopause region and diverging in the winter polar mesopause region.

  2. 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.

  3. The cloud imaging and particle size experiment on the aeronomy of ice in the mesosphere mission: Cloud morphology for the northern 2007 season

    NASA Astrophysics Data System (ADS)

    Rusch, D. W.; Thomas, G. E.; McClintock, W.; Merkel, A. W.; Bailey, S. M.; Russell, J. M., III; Randall, C. E.; Jeppesen, C.; Callan, M.

    2009-03-01

    The Aeronomy of Ice in the Mesosphere (AIM) mission was launched from Vandenberg Air Force Base in California at 4:26:03 EDT on April 25, 2007, becoming the first satellite mission dedicated to the study of noctilucent clouds (NLCs), also known as polar mesospheric clouds (PMC) when viewed from space. We present the first results from one of the three instruments on board the satellite, the Cloud Imaging and Particle Size (CIPS) instrument. CIPS has produced detailed morphology of the Northern 2007 PMC and Southern 2007/2008 seasons with 5 km horizontal spatial resolution. CIPS, with its very large angular field of view, images cloud structures at multiple scattering angles within a narrow spectral bandpass centered at 265 nm. Spatial coverage is 100% above about 70° latitude, where camera views overlap from orbit to orbit, and terminates at about 82°. Spatial coverage decreases to about 50% at the lowest latitudes where data are collected (35°). Cloud structures have for the first time been mapped out over nearly the entire summertime polar region. These structures include [`]ice rings', spatially small but bright clouds, and large regions ([`]ice-free regions') in the heart of the cloud season essentially devoid of ice particles. The ice rings bear a close resemblance to tropospheric convective outflow events, suggesting a point source of mesospheric convection. These rings (often circular arcs) are most likely Type IV NLC ([`]whirls' in the standard World Meteorological Organization (WMO) nomenclature).

  4. TIMED/SABER observations of global gravity wave climatology and their interannual variability from stratosphere to mesosphere lower thermosphere

    NASA Astrophysics Data System (ADS)

    John, Sherine Rachel; Kumar, Karanam Kishore

    2012-09-01

    The present study for the first time reports the global gravity wave activity in terms of their potential energy derived from TIMED/SABER observations right from the stratosphere to the mesosphere lower thermosphere (MLT) region. The potential energy profiles obtained from SABER temperature are validated by comparing them with ground based LIDAR observations over a low latitude site, Gadanki (13.5° N, 79.2° E). The stratospheric and mesospheric global maps of gravity wave energy showed pronounced maxima over high and polar latitudes of the winter hemisphere. The interannual variability of the stratospheric gravity wave activity exhibited prominent annual oscillation over mid-latitudes. The equatorial gravity wave activity exhibited quasi-biennial oscillation in the lower stratosphere and semi-annual oscillation in the upper stratosphere. The MLT region maps revealed summer hemispheric maxima over polar latitudes and secondary maxima over the equatorial region. The results are discussed in the light of present understanding of global gravity wave observations. The significance of the present study lies in emphasizing the importance of satellite measurements in elucidating gravity waves, which is envisaged to have profound impact on parameterizing these waves.

  5. Impacts of Thermal and Wind structures on Mesospheric Short-period Gravity Wave Propagation at High Latitudes

    NASA Astrophysics Data System (ADS)

    Nielsen, Kim; Taylor, Michael J.; Siskind, David; Collins, Richard; Harvey, V. Lynn; Russell, James; Irving, Brita; Negale, Michael

    2012-07-01

    Mesospheric short-period (<1-hr) gravity waves are of great importance for dynamics in the mesosphere-lower thermosphere (MLT) region, and are typically measured by instruments capable of high temporal and/or spatial resolutions, such as lidars and airglow imagers. These waves have been studied extensively at low- and mid-latitudes where known wave sources are well established. The results show strong dependence on the background wind and temperature fields, which can act as a barrier prohibiting vertical propagation of the waves, as well as providing a ducted environment in which the waves can travel large horizontal distances. In fact, results show that up to 75% of these waves may exhibit ducted wave motion. Recent efforts to quantify the existence and nature of these waves over the Antarctic continent have lead to a long-term (10 years) data set obtained with airglow imagers. Our results suggest that these southern polar waves are predominantly freely propagating in the airglow region, in stark contrast to results at other latitudes. A new study in the Arctic enables a comparison between the two data sets. In this work, we investigate the propagation nature of the observed wave field and attempt to identify dominant source regions and potential sources of polar gravity waves through ray tracing.

  6. 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.

  7. Trends in mesospheric ice layers in the Northern Hemisphere during 1961-2013

    NASA Astrophysics Data System (ADS)

    Berger, U.; Lübken, F.-J.

    2015-11-01

    The MIMAS ice model is used to study the trend behavior of polar mesospheric clouds (PMCs) responding to long-term changes in mesospheric temperatures at northern high latitudes for the summer period 1961-2013. This paper presents long-term PMC variations in terms of ice water content (IWC) at northern high latitudes for monthly July averages that are compared to solar backscatter ultraviolet (SBUV) data available in the period 1979-2013. In general, good agreement is found between long-term PMC variations from the model and from satellite observations. For example, both model and SBUV data show an increase in ice water content (IWC > 40 g km-2) in the latitude band 74°-82°N with significant IWC trends of 2.8 ± 2.1 g km-2/dec and 2.4 ± 2.0 g km-2/dec, respectively. Modeled trends in IWC are latitudinally dependent. For the entire period 1961-2013 no trend exists at midlatitudes (50°-60°N) but increases poleward to highly significant values of 4.4 ± 0.9 g km-2/dec in the latitude band 74°-82°N. The analysis of trends in extreme PMC events (IWC > 300 g km-2) shows a 23%/dec increase in occurrence frequency at 74°-82°N which is by far the largest trend of all PMC parameters. We discuss the statistical properties of PMC following an exponential distribution. We derive an analytic solution of ice growth from microphysics that allows calculation of ice particle radius as a function of background conditions. As a result, the thermal conditions near 83 km height, with a cooling of -0.58 ± 0.32 K/dec, mainly determine trends in IWC whereas cooling at lower heights, induced by stratospheric ozone, controls to a large extent the long-term behavior of PMC altitudes.

  8. 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.

  9. Satellite observations of upper stratospheric and mesospheric OH: The HOxdilemma

    NASA Astrophysics Data System (ADS)

    Conway, Robert R.; Summers, Michael E.; Stevens, Michael H.; Cardon, Joel G.; Preusse, Peter; Offermann, Dirk

    2000-09-01

    We report the first observations of the vertical distribution of hydroxyl (OH) from the upper stratosphere to the mesopause. The Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI) made these measurements in August 1997. The data confirm the results from the earlier November 1994 MAHRSI mission that were confined to altitudes above 50 km, namely that mesospheric OH densities are 25 to 35% lower than predicted by standard photochemical theory. However, the new observations show that below 50 km the OH density increases rapidly and at 43 km altitude it is larger than that expected from standard theory. This represents a serious dilemma for our understanding of odd-hydrogen chemistry because the same key reactions are thought to dominate OH/HO2 partitioning in both regions. We show that neither standard photochemical theory nor any previously proposed changes are adequate to explain the OH observations in both the upper stratosphere and mesosphere.

  10. 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.

  11. 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.

  12. Twin mesospheric bores observed over Brazilian equatorial region

    NASA Astrophysics Data System (ADS)

    Medeiros, A. F.; Paulino, I.; Taylor, M. J.; Fechine, J.; Takahashi, H.; Buriti, R. A.; Lima, L. M.; Wrasse, C. M.

    2016-01-01

    Two consecutive mesospheric bores were observed simultaneously by two all-sky cameras on 19 December 2006. The observations were carried out in the northeast of Brazil at two different stations: São João do Cariri (36.5° W, 7.4° S) and Monteiro (37.1° W, 7.9° S), which are by about 85 km apart. The mesospheric bores were observed within an interval of ˜ 3 h in the NIR OH and OI557.7 nm airglow emissions. Both bores propagated to the east and showed similar characteristics. However, the first one exhibited a dark leading front with several trailing waves behind and progressed into a brighter airglow region, while the second bore, observed in the OH layer, was comprised of several bright waves propagating into a darker airglow region. This is the first paper to report events like these, called twin mesospheric bores. The background of the atmosphere during the occurrence of these events was studied by considering the temperature profiles from the TIMED/SABER satellite and wind from a meteor radar.

  13. 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.

  14. 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. PMID:27158586

  15. 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

  16. Retrieval algorithm for densities of mesospheric and lower thermospheric metal and ion species from satellite borne limb emission signals

    NASA Astrophysics Data System (ADS)

    Langowski, M.; Sinnhuber, M.; Aikin, A. C.; von Savigny, C.; Burrows, J. P.

    2013-05-01

    Meteoroids bombard the earth's atmosphere during its orbit around the sun, depositing a highly varying and significant amount of matter into the thermosphere and mesosphere. The strength of the material source needs to be characterized and its impact on atmospheric chemistry assessed. In this study an algorithm for the retrieval of metal and metal ion number densities for a two-dimensional (latitude, altitude) grid is described and explained. Dayglow emission spectra of the mesosphere and lower thermosphere are used, which are obtained by passive satellite remote sensing with the SCIAMACHY instrument on Envisat. The limb scans cover the tangent altitude range from 50 to 150 km. Metals and metal ions are strong emitters in this region and form sharply peaked layers with a FWHM of several 10 km in the mesosphere and lower thermosphere with peak altitudes between 90 to 110 km. The emission signal is first separated from the background signal, arising from Rayleigh and Raman scattering of solar radiation by air molecules. A forward radiative transfer model calculating the slant column density (SCD) from a given vertical distribution was developed. This non-linear model is inverted in an iterative procedure to yield the vertical profiles for the emitting species. Several constraints are applied to the solution, for numerical stability reasons and to get physically reasonable solutions. The algorithm is applied to SCIAMACHY limb-emission observations for the retrieval of Mg and Mg+ using emission signatures at 285.2 and 279.6/280.4 nm, respectively. Results are presented for these three lines as well as error estimations and sensitivity tests on different constraint strength and different separation approaches for the background signal.

  17. 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.

  18. An external template-free route to uniform semiconducting hollow mesospheres and their use in photocatalysis.

    PubMed

    Yang, Di; Wang, Mengye; Zou, Bin; Zhang, Gu Ling; Lin, Zhiqun

    2015-08-14

    Solid amorphous TiO2 mesospheres were synthesized by controlled hydrolysis of Ti-containing precursors. Subsequently, solid TiO2 mesospheres were exploited as scaffolds and subjected to a one-step external template-free hydrothermal treatment, yielding intriguing hollow anatase TiO2 mesospheres. The synthetic protocol was optimized by investigating the effect of buffer reagents and fluoride ions on the formation of hollow TiO2 spheres. The diameter of hollow mesospheres, ranging from 308 to 760 nm, can be readily tailored by varying the precursor concentration. The average thickness of a shell composed of TiO2 nanocrystals was approximately 40 nm with a mean crystal size of 12.4-20.0 nm. Such hollow TiO2 mesospheres possessed a large surface area and were employed in photocatalytic degradation of methylene blue under UV irradiation. Interestingly, the synthetic conditions were found to exert a significant influence on the photocatalytic ability of hollow TiO2 mesospheres. The correlation between the degradation ability of hollow TiO2 mesospheres and the precursor concentration as well as the hydrothermal time was scrutinized. The optimal photocatalytic performance of hollow TiO2 mesospheres was identified.

  19. Supersonic and subsonic measurements of mesospheric ionization.

    NASA Technical Reports Server (NTRS)

    Hale, L. C.; Nickell, L. C.; Kennedy, B.; Powell, T. A.

    1972-01-01

    An Arcas rocket-parachute system was used at night to compare supersonic and subsonic ionization measurements below 75 km. A hemispherical nose-tip probe was used on ascent and a parachute-borne blunt probe on descent to measure polar conductivities, which were due entirely to positive and negative ions. The velocity of the supersonic probe was Mach 2.5 at 50 km and 1.75 at 70 km; the blunt probe was subsonic below 71 km. Between 65 and 75 km the ratio of negative to positive conductivities (and thus of mobilities) determined by the blunt probe was about 1.2, and it approached 1 below this altitude range. The ratio obtained by the nose-tip probe varied from 1.5 at 75 km to .6 at 65 km, thus indicating a rapid variation of the effects of the shock wave on the sampled ions. The absolute values of positive conductivity measured subsonically and supersonically were essentially identical from 60 to 75 km, indicating that the sampled ions were unchanged by the shock. However, below 60 km the shock apparently 'broke up' the positive ions, as indicated by higher measured conductivities.

  20. 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

  1. 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.

  2. 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).

  3. 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.

  4. Experimental Investigations of Oxygen Atom Loss on Mesospheric Dust Surrogates

    NASA Astrophysics Data System (ADS)

    Boulter, J. E.; Marschall, J.; Spangler, E. L.

    2002-12-01

    Inconsistencies have been noted between model predictions and observations of mesospheric composition in narrow regions of the mesosphere. Several arctic rocket campaigns between 1978 and 1993 have observed oxygen atom "bite-outs," narrow layers just below 85 km depleted in atomic oxygen, correlated with NLC observations1. Separate observations from the HALOE instrument on UARS indicated the presence of a band of enhanced water vapor centered near 70 km at mid-latitudes that has not yet been adequately explained by current HOx models2. Because the upper mesosphere and lower thermosphere (MLT) contains a variety of surfaces such as ice particles and ablated meteoric dust, heterogeneous reactions might influence these observed phenomena. Reactions currently being considered are the recombination of oxygen atoms to form molecular oxygen and the reaction of molecular hydrogen with atomic oxygen to form water. To investigate these possible surface-mediated reactions, Knudsen cell experiments have been performed to quantify the oxygen atom recombination coefficient on mineral oxide powders representative of meteoritic composition. Oxygen atoms, produced by means of a microwave frequency discharge, and reagent gases are admitted to a low-pressure, well-mixed reactor in which the loss of the reactant species to a sample surface competes with escape through an exit aperture. Steady state reactant and product concentrations are measured by laser-induced fluorescence and mass spectrometry. By varying the area of the exit orifice in the presence or absence of the surface or reagent gases being investigated, atomic oxygen loss coefficients (γ) can be derived and then related to specific heterogeneous chemical reactions. Preliminary values will be reported for surface-mediated oxygen loss coefficients on several dust surrogates at room temperature and at pressures characteristic of the mesopause region. 1 Gumbel, J., Murtagh, D. P. Espy, P. J., Witt, G., and Schmidlin, F. J., J

  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. White matter injury and microglia/macrophage polarization are strongly linked with age-related long-term deficits in neurological function after stroke

    PubMed Central

    Suenaga, Jun; Hu, Xiaoming; Pu, Hongjian; Shi, Yejie; Hassan, Sulaiman Habib; Xu, Mingyue; Leak, Rehana K.; Stetler, R. Anne; Gao, Yanqin; Chen, Jun

    2015-01-01

    , 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. PMID:25836044

  7. Detection of mesospheric gravity waves in Odin/OSIRIS PMC data in 2002- 2008

    NASA Astrophysics Data System (ADS)

    Petelina, S. V.; Rusch, D. W.

    2008-12-01

    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 2008 is analysed. In the Northern Hemisphere, the PMC brightness around 60+-20 W and around 80+-20 E is up to 30 percent lower than that at other longitudes. In the Southern Hemisphere, the cloud brightness is also 30-60 percent lower around 80+-20 W. We attribute this effect to the influence of gravity waves generated by the Earth's terrain above Greenland and Ural mountains (the natural boundary between Europe and Asia) in the Northern Hemisphere and by the Antarctic Peninsula mountains in the Southern Hemisphere.

  8. 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.

  9. 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.

  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. 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.

  12. Nonmigrating tidal variability in the SABER/TIMED mesospheric ozone

    NASA Astrophysics Data System (ADS)

    Pancheva, D.; Mukhtarov, P.; Smith, A. K.

    2014-06-01

    This paper presents for the first time evidence showing nonmigrating tidal variations in the mesospheric ozone (O3) derived from the Sounding of the Atmosphere using Broadband Emission Radiometry/Thermosphere-Ionosphere-Mesosphere-Energetics and Dynamics (SABER/TIMED) for a full 11 year period, 2002-2012. The O3 tidal fields are extracted from the data by the same method as the temperature tides have been derived. The spatial distribution and seasonal variability of the three strongest nonmigrating O3 tidal variabilities, i.e., SW3, DW2, and DE3, are shown. They demonstrate repeatable presence each year. These O3 tidal variations have large amplitudes at the seasons and latitudes for which the respective temperature (T) tides amplify, i.e., near the equator and during the equinoxes. The phases of the T and O3 tidal signatures are out of phase above 95 km. This phase relationship no longer holds for tidal perturbations below about 90 km. The O3 SW3 and DW2 tidal variations have similar interannual variabilities that appear to follow El Niño-Southern Oscillation variability. The O3 DE3 tidal field, however, has a clear biyearly interannual variability as the biyearly maxima correlate with the westerly phase of the quasi-biennial oscillation in tropical stratospheric winds but only up to 2008.

  13. 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.

  14. 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

  15. Mesospheric Zonal Mean Winds Derived from Consecutive Orbits of AIM Cips Images

    NASA Astrophysics Data System (ADS)

    Rong, P. P.; Yue, J.; Russell, J. M., III; Lumpe, J. D., Jr.; Gong, J.; Wu, D. L.; Randall, C. E.

    2014-12-01

    In order to infer mesospheric wind velocities, polar mesospheric cloud (PMC) pattern variations are investigated using images from consecutive orbits taken by the Cloud Imaging and Particle Size instrument (CIPS) aboard the AIM satellite. CIPS measurements are analyzed to detect patterns that repeat from one orbit to the next, but are displaced in location; the displacement provides a measure of the wind velocity. Pattern matching is achieved by re-sampling the CIPS data to a standard geographic grid with a horizontal resolution of 0.2° longitude × 0.05° latitude (~25 km2), and correlating patterns within geographic frames of size 24° longitude × 3.6° latitude. Such a frame size is arbitrarily chosen, but it covers a hierarchy of cloud structures including scales as large as several hundred kilometers. A relatively larger frame is required because after ~90 minutes, the time of one orbit, the smaller scale features are no longer conserved. Several thousand pairs, taken from 10-14 July 2007, are matched to derive the statistics. These pairs are mostly evenly distributed at longitudes and latitudes north of 70⁰N for each given day. The results suggest that the zonal velocity probability distribution during this 5-day period was peaked at around -40m/s with a 1-σ scatter of ~35m/s. The meridional velocity distribution peaked at 0 m/s with a 1-σ scatter of ~25m/s. These prevailing velocities can be determined with high precision because the corresponding patterns are shifted by at least half of the frame size from one orbit to the next. The CIPS cloud albedo on consecutive orbits is also examined for variations at fixed locations. The statistical results suggest that the mean cloud albedo within a given frame will most likely be weakened or strengthened by < 30% on consecutive orbits, although larger variations can occur with lower probability. Such a conclusion applies to both bright and dim clouds. This indicates that within 90 minutes the cloud brightness

  16. 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

  17. 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

  18. 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

  19. 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

  20. [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.

  1. 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.; Tie, X.; Pan, L.; Figarol, F.; Wu, F.; Brasseur, G. P.

    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.

  2. Quasi 16-day oscillation in the mesosphere and lower thermosphere

    NASA Astrophysics Data System (ADS)

    Forbes, J. M.; Hagan, M. E.; Miyahara, S.; Vial, F.; Manson, A. H.; Meek, C. E.; Portnyagin, Y. I.

    1995-05-01

    A quasi-16-day wave in the mesosphere and lower thermosphere is investigated through analyses of radar data during January/February 1979 and through numerical simulations for various background wind conditions. Previous workers have examined about 19 days of tropospheric and stratospheric data during January 10-28, 1979, and present conflicting evidence as to whether a large westward propagating wavenumber 1 oscillation observed during this period can be identified in terms of the second symmetric Rossby normal mode of zonal wavenumber 1, commonly referred to as the ``16-day wave.'' In the present work we have applied spectral analysis techniques to meridional and zonal winds near 95 km altitude obtained from radar measurements over Obninsk, Russia (54°N, 38°E) and Saskatoon, Canada (52°N, 107°W). These data reveal oscillations of the order of +/-10 m s-1 with a period near 16 days as well as waves with periods near 5 and 10 days. These periodicities all correspond to expected resonant frequencies of atmospheric disturbances associated with westward propagating free Rossby modes of zonal wavenumber 1. Numerical simulations are performed which demonstrate that the 95-km measurements of the 16-day wave are consistent with upward extension of the oscillation determined from the tropospheric and stratospheric data. Noteworthy features of the model in terms of its applicability in the mesosphere/lower thermosphere regime are explicit inclusion of eddy and molecular diffusion of heat and momentum and realistic distributions of mean winds, especially between 80 and 100 km. The latter include a westerly wind regime above the summer easterly mesospheric jet, thus providing a ducting channel enabling interhemispheric penetration of the winter planetary wave disturbance. This serves to explain the appearance of a quasi-16-day wave recently reported in the high-latitude summer mesopause (Williams and Avery, 1992). However, the efficiency of this interhemispheric coupling

  3. Initiation of Sprite Streamers from Natural Mesospheric Structures

    NASA Astrophysics Data System (ADS)

    Liu, N.; Dwyer, J. R.; Stenbaek-Nielsen, H. C.; McHarg, M. G.

    2014-12-01

    Sprites are large, luminous electrical discharges in the upper atmosphere caused by intense cloud-to-ground lightning flashes. They manifest a possible, impulsive coupling mechanism between low atmospheric regions and the upper atmosphere. Their dynamics are governed by filamentary plasma discharges, of tens to hundreds of meter wide, known as streamers. The propagation properties of sprite streamers have been well studied by past work [e.g., Liu, et al., JGR, 114, A00E02, 2009; Liu et al, JGR, 114, A00E03, 2009; Luque and Ebert, Nat. Geosci., 2, 757, 2009; Liu, GRL, 37, L04102, 2010; Luque and Ebert, GRL, 37, L06806, 2010]. However, how sprite streamers are initiated is not well understood. Recent high-speed images show that mesospheric/lower ionospheric structures are frequently involved in initiation of sprite streamers [e.g., Stenbaek-Nielsen et al., Surv. Geophys., 34, 769, 2013; Qin et al., Nat. Comm., 5, 2014]. Although earlier theoretical and numerical studies routinely used strong plasma inhomogeneities to initiate streamers, it is only recently that inhomogeneities are concluded to be required for sprite streamer initiation [e.g., Qin et al., JGR, 116, A06305, 2011; Liu et al., PRL, 109, 025002, 2012; Kosar et al., JGR, 117, A08328, 2012; Kosar et al, GRL, 40, 6282, 2013]. However, the inhomogeneities used in various models are rather ad hoc and often unrealistic. In this talk, we present numerical simulations to show naturally-existing mesospheric structures, such as those produced by gravity waves via instability and breaking [e.g., Fritts and Alexander, Rev. Geophys., 41, 1003, 2003], can initiate sprite streamers under the influence of the measurement-inferred lightning field. Evidence from high-speed video observations supporting this theory is discussed. This mechanism naturally explains many aspects of observed sprite streamer initiation including variability in the delay of sprite initiation, sprites caused by weak lightning, optical signatures of

  4. 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

  5. Coupling Between Mesospheric and Lower-Thermospheric Ducted Gravity Waves

    NASA Astrophysics Data System (ADS)

    Snively, J. B.; Walterscheid, R. L.; Hickey, M. P.

    2011-12-01

    The structure of the mesosphere and lower thermosphere (MLT) region is at times able to support ducted gravity wave propagation in a dual duct system: a lower-thermospheric thermal duct (LTD) that is always present, and an upper-mesospheric thermal duct that forms from an upper-mesospheric inversion layer (MIL). The combined effects of temperature and wind structure (sometimes to the extent of causing "Doppler" ducting, where wind is the Doppler shift becomes the dominant trapping mechanism) may lead to strongly-resonant ducted wave modes that can be easily forced to large amplitude. These modes may be initially excited by mechanisms such as gravity wave breaking or nonlinear interaction at duct altitudes [e.g., Snively and Pasko, JGR, 113, A06303, 2008], or via upward propagating linear waves which tunnel through the lower duct boundaries. In the latter case, excitation to large amplitudes is favored if the wave frequency and wavenumber closely match a duct resonance mode. Even waves that are not fully resonant may tunnel effectively between ducts, leading to dissipation as the waves ascend vertically [e.g., Snively and Taylor, AGU FM, SA54A-04, 2008]. Here we investigate cases where resonant duct modes are shared between the LTD and MIL [e.g., Walterscheid and Hickey, JGR, 114, D19109, 2009], allowing strong waves in the MIL to effectively excite even stronger waves in the LTD. Using steady-state linear and nonlinear time-dependent models in combination, we examine the coupling between MIL and LTD modes, and the generation and evolution of the large amplitude ducted wave modes. The linear model is first used to identify resonance modes, and the nonlinear model is then used to investigate the evolution of waves, from moderate-amplitude quasi-linear waves to large-amplitude nonlinear waves approaching the onset of breaking. We find that waves forced in one duct can profoundly affect the other, especially under resonant conditions where large amplitudes may be

  6. 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.

  7. Cellular automaton modeling of mesospheric optical emissions: Sprites

    SciTech Connect

    Hayakawa, M.; Iudin, D. I.; Mareev, E. A.; Trakhtengerts, V. Y.

    2007-04-15

    This paper presents a new attempt to model two-dimensional mesospheric optical emissions named sprites with the use of a cellular automaton network. A large-scale model of sprites based on the phenomenological percolation-like probabilistic approach is developed to model streamer discharges in sprites. It is shown that a sprite is a self-affine structure rather than a simple fractal one, and that this self-affine structure is tightly connected with directed percolation phenomena. The system is found to evolve in the vicinity of the percolation threshold, which results in a wide variety of sprite characteristics even under similar initial conditions. The approach developed allows us to estimate a maximum size of the discharge pattern to be formed.

  8. Impact of space shuttle orbiter reentry on mesospheric NOx.

    NASA Technical Reports Server (NTRS)

    Stolarski, R. S.; Cicerone, R. J.; Nagy, A. F.

    1973-01-01

    Shuttle orbiter reentry will produce large amounts of nitric oxide (NO) through shock heating at mesospheric altitudes. The effects of this reentry are modeled by considering an impulsive source of NO in time-dependent equations including photochemistry and transport. The model uses an odd-nitrogen approach similar to Strobel's. Parameterized flux boundary conditions are imposed at the mesopause and stratopause and concentrations of the odd nitrogen species (NO, NO2, NO+, N(4S) and N(2D) are found numerically by a finite difference scheme. A localized disturbance can last many hours, depending on the effectiveness of eddy transport. Although the model is one-dimensional, effects of horizontal transport are also included approximately.

  9. 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

  10. 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.

  11. The SMILES observations of mesospheric ozone during the solar eclipse

    NASA Astrophysics Data System (ADS)

    Imai, Koji; Shiotani, Masato; Suzuki, Makoto; Akiyoshi, Hideharu; Ebisawa, Ken; Takahashi, Kenshi; Yamashita, Yousuke; Imamura, Takashi

    Solar eclipse temporally reduces the amount of solar radiation, providing an opportunity to verify the mesospheric ozone photochemistry under a changing solar radiation. During the annular solar eclipse occurred on 15 January 2010, Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) successfully observed the temporal changes in ozone concentration between at 52 and 76 km. Analysis of the data with an atmospheric chemistry box model showed that, (i) the lower the altitude is, the closer to the normal nighttime average the concentration near the maximum eclipse obscuration becomes, and (ii) even if there were the SMILES observation points under similar degrees of obscuration, the concentrations measured at an altitude differed between the sunlight increasing and decreasing phases.

  12. 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.

  13. A multidiagnostic investigation of the mesospheric bore phenomenon

    NASA Astrophysics Data System (ADS)

    Smith, Steven M.; Taylor, Michael J.; Swenson, Gary R.; She, Chiao-Yao; Hocking, Wayne; Baumgardner, Jeffrey; Mendillo, Michael

    2003-02-01

    Imaging measurements of a bright wave event in the nighttime mesosphere were made on 14 November 1999 at two sites separated by over 500 km in the southwestern United States. The event was characterized by a sharp onset of a series of extensive wavefronts that propagated across the entire sky. The waves were easily visible to the naked eye, and the entire event was observed for at least 5? hours. The event was observed using three wide-angle imaging systems located at the Boston University field station at McDonald Observatory (MDO), Fort Davis, Texas, and the Starfire Optical Range (SOR), Albuquerque, New Mexico. The spaced imaging measurements provided a unique opportunity to estimate the physical extent and time history of the disturbance. Simultaneous radar neutral wind measurements in the 82 to 98 km altitude region were also made at the SOR which indicated that a strong vertical wind shear of 19.5 ms-1km-1 occurred between 80 and 95 km just prior to the appearance of the disturbance. Simultaneous lidar temperature and density measurements made at Fort Collins, Colorado, ˜1100 km north of MDO, show the presence of a large (˜50 K) temperature inversion layer at the time of the wave event. The observations indicated that the event was most probably due to an undular mesospheric bore, a relatively uncommon disturbance which has only recently been reported [, 1995a]. Evidence is also shown to suggest that a large east-west tropospheric frontal system lying over the northern United States was the origin of the disturbance.

  14. 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.

  15. 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

  16. 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

  17. 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…

  18. 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.

  19. Jupiter's Mesospheric Structure and Shape From Occultation of SAO 92746 (HIP 9369)

    NASA Astrophysics Data System (ADS)

    Hubbard, W. B.; Hill, R.; Rieke, M. J.; Drossart, P.; Roques, F.; Sicardy, B.; Widemann, T.; Doyon, R.; Nadeau, D.; Marley, M.

    2000-10-01

    The magnitude-7 star was occulted by Jupiter's high northern atmosphere on 10 October 1999. We report results from high-quality observations obtained at VLT (Chile), Kitt Peak and Catalina Station (Arizona), and Mt. Megantic (Canada). Our observations cover a jovian latitude range from 55 deg N to 73 deg N, and, when combined with data sets from stellar occultations in 1971 and 1989, with Voyager and Galileo Probe data, and with independent astrometry, enable us to investigate the overall oblateness of the jovian mesosphere at pressures of ~ 1 μ bar. Our high-jovian-latitude data sets probe a portion of the jovian atmosphere that may be subjected to auroral heating -- we compare our observed lightcurves with lightcurves predicted for auroral temperature-pressure profiles. For the Galileo Probe temperature (T) vs. pressure (P) profile, applicable to low latitudes, a single-parameter fit to a stellar occultation lightcurve yields an effective refractivity scale height (H) of 24 km. If this same T-P profile is applied to high latitudes, the effective H is about 21 km. With auroral heating, the inferred H increases to about 28 km. There is considerable scatter in the H values obtained from the 1999 occultation data, but some indication of the higher H values consistent with auroral heating. The oblateness e for the jovian atmosphere that we infer from the data sets lies between the dynamical oblateness e=0.06493 of Lindal et al. (JGR 86, 8721-8727, 1981), and the value derived from the 1971 β Sco occultation by Hubbard and Van Flandern, e=0.060 +/- 0.001 (AJ 77, 65-74, 1972). Thus, there is evidence that the polar jovian atmosphere at microbar pressures is ~ 100 km farther from the center of mass than would be the case for a barotropic planet in hydrostatic equilibrium. Supported in part by NASA Planetary Astronomy Program.

  20. 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.

  1. A matter of symmetry: terahertz polarization detection properties of a multi-contact photoconductive antenna evaluated by a response matrix analysis.

    PubMed

    Niehues, Gudrun; Funkner, Stefan; Bulgarevich, Dmitry S; Tsuzuki, Satoshi; Furuya, Takashi; Yamamoto, Koji; Shiwa, Mitsuharu; Tani, Masahiko

    2015-06-15

    While terahertz time domain spectroscopy (THz-TDS) is a well-established technique, polarization sensitive measurements are challenging due to the need of broadband polarization devices. Here, we characterize our recently introduced multi-contact photoconductive detector antenna with a response matrix analysis. We show that the lead lines attached to electrodes reduce the antenna symmetry and thereby influence the properties of the response matrices. With a wire grid polarizer, we simulate a sample influencing the polarization angle and the intensity of the incident THz pulse. Evaluating the measurements with the response matrix analysis, our results show a well agreement of the adjusted and measured polarization angles and intensities over a frequency range from 0.25 to 0.8 THz.

  2. Retrieval algorithm for densities of mesospheric and lower thermospheric metal atom and ion species from satellite-borne limb emission signals

    NASA Astrophysics Data System (ADS)

    Langowski, M.; Sinnhuber, M.; Aikin, A. C.; von Savigny, C.; Burrows, J. P.

    2014-01-01

    Meteoroids bombard Earth's atmosphere during its orbit around the Sun, depositing a highly varying and significant amount of matter into the thermosphere and mesosphere. The strength of the material source needs to be characterized and its impact on atmospheric chemistry assessed. In this study an algorithm for the retrieval of metal atom and ion number densities for a two-dimensional (latitude, altitude) grid is described and explained. Dayglow emission spectra of the mesosphere and lower thermosphere are used, which are obtained by passive satellite remote sensing with the SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) instrument on board Envisat. The limb scans cover the tangent altitude range from 50 to 150 km. Metal atoms and ions are strong emitters in this region and form sharply peaked layers with a FWHM (full width at half maximum) of several 10 km in the mesosphere and lower thermosphere measuring peak altitudes between 90 to 110 km. The emission signal is first separated from the background signal, arising from Rayleigh and Raman scattering of solar radiation by air molecules. A forward radiative transfer model calculating the slant column density (SCD) from a given vertical distribution was developed. This nonlinear model is inverted in an iterative procedure to yield the vertical profiles for the emitting species. Several constraints are applied to the solution for numerical stability reasons and to get physically reasonable solutions. The algorithm is applied to SCIAMACHY limb-emission observations for the retrieval of Mg and Mg+ using emission signatures at 285.2 and 279.6/280.4 nm, respectively. Results are presented for these three lines as well as error estimations and sensitivity tests on different constraint strength and different separation approaches for the background signal.

  3. Error analysis for mesospheric temperature profiling by absorptive occultation sensors

    NASA Astrophysics Data System (ADS)

    Rieder, M. J.; Kirchengast, G.

    2001-01-01

    An error analysis for mesospheric profiles retrieved from absorptive occultation data has been performed, starting with realistic error assumptions as would apply to intensity data collected by available high-precision UV photodiode sensors. Propagation of statistical errors was investigated through the complete retrieval chain from measured intensity profiles to atmospheric density, pressure, and temperature profiles. We assumed unbiased errors as the occultation method is essentially self-calibrating and straight-line propagation of occulted signals as we focus on heights of 50 100 km, where refractive bending of the sensed radiation is negligible. Throughout the analysis the errors were characterized at each retrieval step by their mean profile, their covariance matrix and their probability density function (pdf). This furnishes, compared to a variance-only estimation, a much improved insight into the error propagation mechanism. We applied the procedure to a baseline analysis of the performance of a recently proposed solar UV occultation sensor (SMAS Sun Monitor and Atmospheric Sounder) and provide, using a reasonable exponential atmospheric model as background, results on error standard deviations and error correlation functions of density, pressure, and temperature profiles. Two different sensor photodiode assumptions are discussed, respectively, diamond diodes (DD) with 0.03% and silicon diodes (SD) with 0.1% (unattenuated intensity) measurement noise at 10 Hz sampling rate. A factor-of-2 margin was applied to these noise values in order to roughly account for unmodeled cross section uncertainties. Within the entire height domain (50 100 km) we find temperature to be retrieved to better than 0.3 K (DD) / 1 K (SD) accuracy, respectively, at 2 km height resolution. The results indicate that absorptive occultations acquired by a SMAS-type sensor could provide mesospheric profiles of fundamental variables such as temperature with unprecedented accuracy and

  4. 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

  5. Finland HF and Esrange MST radar observations of polar mesosphere summer echoes

    NASA Astrophysics Data System (ADS)

    Ogawa, T.; Arnold, N. F.; Kirkwood, S.; Nishitani, N.; Lester, M.

    2003-04-01

    Peculiar near range echoes observed in summer with the SuperDARN HF radar in Finland are presented. The echoes were detected at four frequencies of 9, 11, 13 and 15 MHz at slant ranges of 105 250 km for about 100 min. Interferometer measurements indicate that the echoes are returned from 80 100 km altitudes with elevation angles of 20° 60

  6. 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

  7. Density and pressure variability in the mesosphere and thermosphere

    NASA Technical Reports Server (NTRS)

    Davis, T. M.

    1986-01-01

    In an effort to isolate the essential physics of the mesosphere and the thermosphere, a steady one-dimensional density and pressure model has been developed in support of related NASA activities, i.e., projects such as the AOTV and the Space Station. The model incorporates a zeroth order basic state including both the three-dimensional wind field and its associated shear structure, etc. A first order wave field is also incorporated in period bands ranging from about one second to one day. Both basic state and perturbation quantities satsify the combined constraints of mass, linear momentum and energy conservation on the midlatitude beta plane. A numerical (iterative) technique is used to solve for the vertical wind which is coupled to the density and pressure fields. The temperature structure from 1 to 1000 km and the lower boundary conditions are specified using the U.S. Standard Atmosphere 1976. Vertical winds are initialized at the top of the Planetary Boundary Layer using Ekman pumping values over flat terrain. The model also allows for the generation of waves during the geostrophic adjustment process and incorporates wave nonlinearity effects.

  8. 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.

  9. 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.

  10. VHF power scattered from the mesosphere at mid-latitudes

    NASA Technical Reports Server (NTRS)

    Royrvik, O.; Gibbs, K. P.; Bowhill, S. A.

    1982-01-01

    Scattered power profiles from the Urbana VHF radar have been analyzed. Coherent power returns from the mesosphere (60-90 km) show that a large portion of these returns occur in well-defined stable layers lasting for more than 6 hours in some cases. It is concluded that some of these layers may be caused by standing diurnal tides. Short time variation in scattered power is attributed to internal gravity waves modifying the amplitude and altitude of maximum vertical shear in the horizontal wind. Correlation time of the scattered signal varies with altitude as well as with scattered power. Seasonal averages of the scattered power show a broad peak around 76 km. The decrease in scattered power below 76 km appears because of a decrease in the electron density gradient, while the decrease above 76 km is due to a decrease in the intensity of turbulence. The amplitude of short-period gravity waves shows a decrease with altitude below 66 km, attributed to the Brunt-Vaisala barrier, and a slight increase with altitude above 70 km. The dominant period of the vertical oscillations shows an increase above 63 km, giving further evidence that the high-frequency oscillations present below 63 km cannot propagate to higher altitudes.

  11. 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

  12. Silicon chemistry in the mesosphere and lower thermosphere

    NASA Astrophysics Data System (ADS)

    Plane, John; Gómez-Martín, Juan Carlos; Feng, Wuhu; Janches, Diego

    2016-04-01

    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 2-step hydration to silicylic 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.

  13. Silicon chemistry in the mesosphere and lower thermosphere

    NASA Astrophysics Data System (ADS)

    Plane, John M. C.; Gómez-Martín, Juan Carlos; Feng, Wuhu; Janches, Diego

    2016-04-01

    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.

  14. Planetary and Gravity Waves in the Mesosphere and Lower Thermosphere

    NASA Technical Reports Server (NTRS)

    Vincent, R. A.

    1985-01-01

    Rocket and ground based studies of the mesosphere and lower thermosphere show that waves play an important role in the dynamics of their region. The waves manifest themselves in wind, temperature, density, pressure, ionization and airglow fluctuations in the 80-120 km height range. Rockets have enabled the density and temperature structure to be measured with excellent height resolution, while long term studies of wind motions using MST, partial reflection and meteor radars and, more recently, lidar investigations of temperature and density, have enabled the temporal behaviour of the waves to be better understood. A composite of power spectra is shown of wind motions measured near the mesopause at widely separated locations and illustrates how wave energy is distributed as a function of frequency. The spectra show three distinct parts; (1) a long period section corresponding to periods longer than 24 h; (2) a section between 12 and 24 h priod where the spectra are dominated by narrow; peaks associated with the semidiurnal and diurnal tides and (3) a section at periods less than 12 h where the spectral density decreases montonically (except for the 8 h tidal peak). The long period section is associated with transient planetary scale waves while the short period motions are caused by gravity waves.

  15. 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 adsorption wavelength. Two pulsed laser systems were constructed, one producing as much as 0.6 J of sodium resonance radiation at a 10-Hz repetition rate and another producing as much as 24 mJ at a 840-Hz repetition rate. In both laser systems, the 1.06-micron and 1.32-micron Nd:YAG lasers are configured as mode-locked master oscillators followed by power amplifiers. Other aspects of this project are presented.

  16. Nighttime mesospheric returns associated with a large scale flare event

    NASA Technical Reports Server (NTRS)

    Bowhill, S. A.

    1983-01-01

    Magnetic storms associated with large flares can give D region ionization. Special measurements are made at night to evaluate the nature of mesospheric returns obtained under storm conditions. Five periods of time are tabulated varying in length from 20 min to 60 min at which scattered power is observed above the noise level. The three values of k(p) corresponding to the five periods are also given, as is the mean power over noise observed. The scattered powers from 78 to 81 km are comparable with those observed during the day, indicating that a similar ionization density is present. The peak power levels are approximately the same in both cases; but whereas the night data come from an essentially zero background, the day data arise from a substantial level of background scatter. This implies that the periods indicated are the only times at which any substantial particle precipitation is taking place; and that the consequent ionization is confined to the height region shown.

  17. 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.

  18. 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.

  19. 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

  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. Interpretation of radar returns from the mesosphere, part 2.3A

    NASA Technical Reports Server (NTRS)

    Royrvik, O.

    1984-01-01

    The study of VHF radar signals from the mesosphere has shown that neutral atmosphere turbulence plays a central role in generating the refractive index irregularities that backscatter the radio waves. It follows that an increase in the turbulent energy dissipation rate will result in a decrease in signal correlation time and an increase in scattered signal power. Thus, in turbulence-generated radar echoes a negative correlation between echo power and signal correlation time (P/C) is expected. P/C also changes as a function of altitude, i.e., it is negative in the upper mesosphere but largely positive in the lower, with the latter thought to be a manifestation of partial reflection from stratified layers of refractive index gradient. Partial reflection would also explain the vertical aspect sensitivity of the scattered signal in the lower mesosphere.

  2. Carbon dioxide and oxygen isotope anomalies in the mesosphere and stratosphere

    SciTech Connect

    Thiemens, M.H.; Jackson, T.; Zipf, E.C.

    1995-11-10

    Isotopic ({delta}{sup 17}O and {delta}{sup 18}O) measurements of stratospheric and mesospheric carbon dioxide (CO{sub 2}) and oxygen (O{sub 2}), along with trace species concentrations (N{sub 2}O, CO, and CO{sub 2}), were made in samples collected from a rocket-borne cryogenic whole air sampler. A large mass-independent isotopic anomaly was observed in CO{sub 2}, which may in part derive from photochemical coupling to ozone (O{sub 3}). The data also require an additional isotopic fractionation process, which is presently unidentified. Mesospheric O{sub 2} isotope ratios differed from those in the troposphere and stratosphere. The cause of this isotopic variation in O{sub 2} is presently unknown. The inability to account for these observations represents a fundamental gap in the understanding of the O{sub 2} chemistry in the stratosphere and mesosphere. 28 refs., 2 figs., 1 tab.

  3. Daytime lidar measurements of tidal winds in the mesospheric sodium layer at Urbana, Illinois

    NASA Technical Reports Server (NTRS)

    Kwon, K. H.; Senft, D. C.; Gardner, C. S.; Voelz, D. G.; Sechrist, C. F., Jr.; Roesler, F. L.

    1986-01-01

    For more than 15 years lidar systems have been used to study the chemistry and dynamics of the mesospheric sodium layer. Because the layer is an excellent tracer of atmospheric wave motions, sodium lidar has proven to be particularly useful for studying the influence of gravity waves and tides on mesospheric dynamics. These waves, which originate in the troposphere and stratosphere, propagate through the mesosphere and dissipate their energy near the mesopause making important contributions to the momentum and turbulence budget in this region of the atmosphere. Recently, the sodium lidar was modified for daytime operation so that wave phenomena and chemical effects could be monitored throughout the complete diurnal cycle. The results of continuous 24 hour lidar observations of the sodium layer structure are presented alond with measurement of the semidiurnal tidal winds.

  4. Model/data comparisons of ozone in the upper stratosphere and mesosphere

    NASA Technical Reports Server (NTRS)

    Siskind, David E.; Remsberg, Ellis E.; Eckman, Richard S.; Connor, Brian J.; Tsou, J. J.; Parrish, Alan

    1994-01-01

    We compare ground-based microwave observations of ozone in the upper stratosphere and mesosphere with daytime observations made from the SME (Solar Mesosphere Explorer) satellite, with nighttime data from the LIMS instrument, and with a diurnal photochemical model. The results suggest that the data are all in reasonable agreement and that the model-data discrepancy is much less than previously thought, particularly in the mesosphere. This appears to be due to the fact that the latest data are lower than earlier reports and the updated model predicts more ozone than older versions. The model and the data agree to within a factor of 1.5 at all altitudes and typically are within 20 percent.

  5. TIMED Doppler Interferometer on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite: Data product overview

    NASA Astrophysics Data System (ADS)

    Niciejewski, R.; Wu, Q.; Skinner, W.; Gell, D.; Cooper, M.; Marshall, A.; Killeen, T.; Solomon, S.; Ortland, D.

    2006-11-01

    The TIMED Doppler Interferometer (TIDI) performs the measurement of upper atmospheric winds on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite. This is an optimized single etalon Fabry Perot interferometer that records the slight Doppler shift of individual emission features of the O2 (0,0) atmospheric band. The interferometer operates at a 100% duty cycle obtaining neutral wind altitude profiles on a global basis. The measurements are synoptic and provide an uninterrupted long-term climatological record of the dynamics in the mesosphere and lower thermosphere regions. The data products from TIDI include (1) apparent line of sight winds and integrated brightness, (2) inverted line of sight winds and volume emission rate, and (3) inverted horizontal neutral wind fields on an evenly spaced track angle/altitude grid. The data products demonstrate an interannual variability in the tidal structure of the mesosphere and the lower thermosphere and an inherent daily geophysical variance.

  6. Do the OH Meinel bands provide mesospheric temperatures?

    NASA Astrophysics Data System (ADS)

    Slanger, Tom

    2016-04-01

    It is customary to determine local temperatures in the mesosphere and MLT by using Boltzmann plots based on the rotational distributions of the bands of the OH Meinel system, assuming that populations in these levels are in local thermodynamic equilibrium (LTE) with the kinetic temperature [Beig et al., Rev. Geophys., 2003; Turnbull and Lowe, PSS, 1989; von Savigny and Lednyts'kyy, GRL, 2013]. It has long been known that the higher rotational levels are not in LTE [Dodd et al., JGR,1994], so that a conventional Boltzmann plot cannot be used to obtain a temperature - only the lowest rotational levels are used, in the hope that LTE for such levels is appropriate. Because the atmosphere is dynamically active, it is important that the OH bands be observed simultaneously, particularly if the intent is to compare apparent temperatures from different vibrational levels. Using sky spectra from the Keck II telescope and the ESI echelle spectrograph, it has been shown that the LTE assumption seems to be invalid even for low rotational levels, based on earlier observations that show a reproducible pattern of apparent temperature vs OH vibrational level, with a general upward trend of temperature with increasing vibrational level, averaging 15-20 K [Cosby and Slanger, Can. J. Phys, 2007]. This work has now been repeated with a much larger database. using the X-shooter telescope and echelle spectrograph at the VLT (Very Large Telescope) in Chile [Noll et al., ACPD, 2015]. The results are in close accord with the earlier work, showing the same general pattern, with a marked temperature maximum at OH(v = 8), and an upward "temperature" trend from v = 2 to v = 9. As the OH layer lies below the mesopause, kinetic temperatures should fall from that layer ( 87 km) to the mesopause, near 95 km. Typically the modeled temperature in the OH layer is 17 K higher than that in the O2(b,v=0) layer [NRLMSIS00]. Rocket and satellite experiments indicate that there is a trend in altitude of the

  7. Nucleation of mesospheric cloud particles: Sensitivities and limits

    NASA Astrophysics Data System (ADS)

    Wilms, Henrike; Rapp, Markus; Kirsch, Annekatrin

    2016-03-01

    Nucleation of mesospheric ice particles is thought to occur via heterogeneous nucleation on meteor smoke particles. However, several factors determining the nucleation rate are poorly known. To study the effect of uncertainties in the nucleation rate on cloud properties, we use the Community Aerosol and Radiation Model for Atmospheres and systematically vary the nucleation rate over ±10 orders of magnitude. In one set of simulations, the background state of the atmosphere is described by climatological conditions. In a second set, gravity wave-perturbed profiles from the Kühlungsborn Mechanistic general Circulation Model (KMCM) are used with typical temperature (vertical wind) perturbations at the mesopause on the order of 9 K (0.45 m/s). The resulting noctilucent cloud (NLC) characteristics are compared to lidar and satellite measurements. Realistic NLCs compared to the lidar measurements can only be modeled if the nucleation rate is reduced by up to 3 orders of magnitude compared to standard assumptions. For the same cases, the simulated NLCs compare best to the satellite measurements if the nucleation rate is reduced by 2 orders of magnitude or more. Dynamical processes at the mesopause strongly influence the NLC development. In a gravity wave-perturbed atmosphere, the ice particles have only limited time for nucleation and growth. The growth time is limited by the vertical wind, because the vertical wind determines the residence time of the ice particles in the supersaturated region. Since the vertical wind amplitudes reach 1.5 m/s in KMCM (compared to a mean upwelling of ˜4 cm/s in the climatology), the ice particles remain significantly smaller in a gravity wave-perturbed atmosphere than in climatological background conditions.

  8. Correlated measurements of mesospheric density and near infrared airglow

    NASA Astrophysics Data System (ADS)

    Moreels, G.; Pautet, D.; Faivre, M.; Keckhut, P.; Hauchecorne, A.

    A program aimed at simultaneously measuring the mesospheric density and the evolution with time of the near IR emission at the mesopause level was initiated in July 2000 and July 2001. The atmospheric density is measured along a vertical line using the Rayleigh scattering lidar located at Observatoire de Haute Provence (OHP). The near IR emission, mainly due to OH, is measured along a slant path from the Pic de Château-Renard (Hautes-Alpes, altitude 2989 m). The field of view of the CCD camera encompasses an area located vertically above OHP. Rayleigh scattering by air molecules is much less efficient than fluorescence by alkaline atoms. Therefore, the lidar data could only be retrieved with a one-hour time resolution at altitudes of 65, 70, 72.5 and 75 km. The time resolution for the airglow intensity measurement was equal to three minutes. The temporal evolution over the 5-hour duration of the night appears as opposite in the density up to 75 km and in the near IR airglow. The airglow shows around 23h30 a minimum intensity about 28% lower than its maximum value. During the first part of the night the intensity decreases. During the second part, it increases. The increase during the second part cannot be explained by the evolution of the atmospheric chemical system. Given the variation in opposite phases of the air density and of the emission, it is suggested that the near IR airglow is a semi-direct tracer of the density variations at the mesopause level, the air molecules being effective quenchers of the excited OH radicals. The excitation and quenching rates will therefore be discussed. Two short movie films showing the airglow waves coming across the observation field of view will be presented.

  9. Lidar observations of mesospheric Fe and sporadic Fe layers at Urbana, Illinois

    NASA Technical Reports Server (NTRS)

    Bills, Richard E.; Gardner, Chester S.

    1990-01-01

    Lidar measurements of mesospheric Fe at Urbana, Illinois were conducted during 4 nights in October, 1989. The average Fe abundances were in the range (1.0-2.0) X 10 to the 10/sq cm. The layer centroid heights range between 89.0 and 90.5 km and the rms widths vary between 3.2 and 4.1 km. Considerable gravity wave and tidal activity are observed in the Fe profiles. The observations are compared with previous measurements of mesospheric Fe and with observations of sporadic Na (Na/S/) layers.

  10. Method for remotely measuring the spin-damping time of mesospheric sodium.

    PubMed

    Li, Lihang; Wang, Hongyan; Hua, Weihong; Ning, Yu; Xu, Xiaojun

    2016-09-01

    By using the return flux enhancement factor due to repumping, the spin-damping time of mesospheric sodium can be estimated. Because the absolute return photon number does not need to be measured, this method is independent of sodium abundance. An example of how to find the spin-damping time using this method is given. As a result, it is shown that this method is sensitive and has the potential to improve the precision of the spin-damping time estimations of mesospheric sodium. Finally, the impact of the geomagnetic field on this method is analyzed. PMID:27607983

  11. University of Michigan ground-based circle-to-line Fabry-Perot interferometer and its applications in mesosphere and lower thermosphere dynamics studies

    SciTech Connect

    Wang, J.; Wu, J.; Hays, P.B.

    1994-12-31

    An advanced Fabry-Perot interferometer with an innovative focal plane detection technique called the Circle-to-Line Interferometer Optical (CLIO) system and high quantum efficiency CCD has been developed and field tested. During the field test at Ann Arbor, Michigan, 9 interference orders were collected simultaneously for the OH(7,3) P{sub 1}(3). A signal-to-noise ratio (SNR) of 10-100 was achieved with 1-minute integration. Compared with conventional FPI, the CLIO-FPI is more sensitive and capable of collecting airglow data at much higher temporal resolution. The first operational CLIO-FPI will be deployed at the Polar Cap Observatory (PCO) at Resolute, Northwest Territories, Canada (74{degree}54{prime}N, 94{degree}54{prime}W), in 1994. This new instrument is expected to enhance the ability to study the Earth`s mesosphere and lower thermosphere.

  12. Energetic Charged Particle Component or the NO(y) Budget of the Polar Middle Atmosphere

    NASA Technical Reports Server (NTRS)

    Vitt, F. M.; Jackman, C. H.

    1999-01-01

    Analysis of nitrates measured in polar ice cap snow at a high resolution shows large variations in the nitrates. It has been shown that the nitrate signal may contain a signature of solar activity [Zeller and Dreschhoff, 19951. Reactive odd nitrogen production associated with solar particle events (SPEs) and auroral activity may be a source of some of the nitrate anomalies observed in the polar ice caps. Periods of large SPEs can lead to a production of polar atmospheric odd nitrogen in excess of the ambient sources in the polar stratosphere and mesosphere, and may leave a large nitrate signal stratified in the polar ice cap. Auroral electrons and photoelectrons produce odd nitrogen in the thermosphere, some of which may be transported to the polar (>50 degrees) mesosphere and stratosphere. Sources of odd nitrogen in the polar middle atmosphere associated with SPEs, galactic cosmic rays, and auroral electron precipitation have been quantified. The relative contributions by the energetic particles sources to the Noy budget of the polar middle atmosphere (from tropopause to 50 km, from 50 degrees to 90 degrees latitude) are compared with the nitrates observed in the polar ice sheets.

  13. Artificial electron heating of winter mesospheric radar clouds (PMWE) and the interpretation of the radar backscatter variation during the heater cycling.

    NASA Astrophysics Data System (ADS)

    Kassa Bekele, Meseret; Havnes, Ove; La Hoz, Cesar; Baroni, Giovanni; Rietveld, Mike; Biebricher, Alexander

    The effect of artificial electron heating (in our case with the EISCAT Heating Facility) on the Polar Mesospheric Winter Echoes (PMWE) the weak radar clouds which occur in the winter mesosphere between heights 55 to 80 km, is normally different from its effect on the much stronger Polar Mesospheric Summer Echoes (PMSE) which occur between 80 and 90 km height. They both show a weakening of the backscatter when the heater is switched on, sometimes close to extinguishing of the radar backscatter, signaling that the increased electron pressure has smoothed the electron density gradients which are responsible for the coherent backscatter. However, while the PMSE backscatter very often show a considerable recovery during the 20 sec the heater (normally) is on and dust particles are charged more negatively by the heated electrons, this recovery is at best very weak for PMWE. The PMWE also have weak overshoots, where the backscatter flares up only by a factor 1.1 to 1.2 when the heater is switched off, compared to the undisturbed PMWE backscatter before the heater was switched on. For PMSE the overshoot factor can be as high as 7. This demonstrate that if dust particles control the PMWE their sizes must be much smaller than the PMSE particles. Modeling has shown that the likely PMWE dust sizes are in the range 3-4 nanometer making it probable that PMWE is associated with the small meteoric smoke particles. When the heater is switched off the charge of the dust particles and the intensity of the backscatter relax back to its undisturbed values. If the decharging mechanism was the same for the larger PMSE and the small PMWE dust particles one would expect a very much longer relaxation time for the PMWE than for the PMSE. The fact that the PMWE relaxation time is comparable to the PMSE show that the small meteoric dust particles must be de-charged by a more effective mechanism than ion attachment. We find that the photodetachment effect where photons of energy less than the

  14. Nighttime mesospheric hydroxyl enhancements during SEP events and accompanying geomagnetic storms: Ionization rate modeling and Aura satellite observations

    NASA Astrophysics Data System (ADS)

    Verkhoglyadova, O. P.; Wissing, J. M.; Wang, S.; Kallenrode, M.-B.; Zank, G. P.

    2016-07-01

    We quantify the effects of combined precipitating solar protons and magnetospheric electrons on nighttime odd hydrogen density enhancements during two solar energetic particle (SEP) events accompanied by strong geomagnetic storms. We perform detailed modeling of ionization rates for 7-17 November 2004 and 20-30 August 2005 intervals with improved version 1.6 of the Atmospheric Ionization Module Osnabrück model. Particle measurements from Geostationary Operational Environmental Satellites and Polar Orbiting Environmental Satellites are sorted and combined in 2 h intervals to create realistic particle precipitation maps that are used as the modeling input. We show that modeled atmospheric ionization rates and estimated peak odd hydrogen (primarily hydroxyl) production from 0.001 hPa to 0.1 hPa atmospheric pressure levels during these intervals are consistent with enhancements in nighttime averaged zonal odd hydrogen densities derived from newly reprocessed and improved data set of Microwave Limb Sounder instrument on board Aura satellite. We show that both precipitating SEPs and magnetospheric electrons contribute to mesospheric ionization and their relative contributions change throughout the intervals. Our event-based modeling results underline the importance of the combined ionization sources for odd hydrogen chemistry in the middle atmosphere.

  15. Cross-Polarized Magic-Angle Spinning (sup13)C Nuclear Magnetic Resonance Spectroscopic Characterization of Soil Organic Matter Relative to Culturable Bacterial Species Composition and Sustained Biological Control of Pythium Root Rot.

    PubMed

    Boehm, M J; Wu, T; Stone, A G; Kraakman, B; Iannotti, D A; Wilson, G E; Madden, L V; Hoitink, H

    1997-01-01

    We report the use of a model system that examines the dynamics of biological energy availability in organic matter in a sphagnum peat potting mix critical to sustenance of microorganism-mediated biological control of pythium root rot, a soilborne plant disease caused by Pythium ultimum. The concentration of readily degradable carbohydrate in the peat, mostly present as cellulose, was characterized by cross-polarized magic-angle spinning (sup13)C nuclear magnetic resonance spectroscopy. A decrease in the carbohydrate concentration in the mix was observed during the initial 10 weeks after potting as the rate of hydrolysis of fluorescein diacetate declined below a critical threshold level required for biological control of pythium root rot. Throughout this period, total microbial biomass and activity, based on rates of [(sup14)C]acetate incorporation into phospholipids, did not change but shifts in culturable bacterial species composition occurred. Species capable of inducing biocontrol were succeeded by pleomorphic gram-positive genera and putative oligotrophs not or less effective in control. We conclude that sustained efficacy of naturally occurring biocontrol agents was limited by energy availability to this microflora within the organic matter contained in the potting mix. We propose that this critical role of organic matter may be a key factor explaining the variability in efficacy typically encountered in the control of pythium root rot with biocontrol agents. PMID:16535481

  16. Cross-Polarized Magic-Angle Spinning (sup13)C Nuclear Magnetic Resonance Spectroscopic Characterization of Soil Organic Matter Relative to Culturable Bacterial Species Composition and Sustained Biological Control of Pythium Root Rot

    PubMed Central

    Boehm, M. J.; Wu, T.; Stone, A. G.; Kraakman, B.; Iannotti, D. A.; Wilson, G. E.; Madden, L. V.; Hoitink, H.

    1997-01-01

    We report the use of a model system that examines the dynamics of biological energy availability in organic matter in a sphagnum peat potting mix critical to sustenance of microorganism-mediated biological control of pythium root rot, a soilborne plant disease caused by Pythium ultimum. The concentration of readily degradable carbohydrate in the peat, mostly present as cellulose, was characterized by cross-polarized magic-angle spinning (sup13)C nuclear magnetic resonance spectroscopy. A decrease in the carbohydrate concentration in the mix was observed during the initial 10 weeks after potting as the rate of hydrolysis of fluorescein diacetate declined below a critical threshold level required for biological control of pythium root rot. Throughout this period, total microbial biomass and activity, based on rates of [(sup14)C]acetate incorporation into phospholipids, did not change but shifts in culturable bacterial species composition occurred. Species capable of inducing biocontrol were succeeded by pleomorphic gram-positive genera and putative oligotrophs not or less effective in control. We conclude that sustained efficacy of naturally occurring biocontrol agents was limited by energy availability to this microflora within the organic matter contained in the potting mix. We propose that this critical role of organic matter may be a key factor explaining the variability in efficacy typically encountered in the control of pythium root rot with biocontrol agents. PMID:16535481

  17. Inter-Hemispheric Coupling During Recent North Polar Summer Periods as Predicted by MaCWAVE/MIDAS Rocket Data and Traced by TIMED/SABER Measurements

    NASA Technical Reports Server (NTRS)

    Goldberg, Richard A.; Feofilov, Artem G.; Kutepov, Alexander A.; Pesnell W. Dean; Schmidlin, Francis J.

    2011-01-01

    In July, 2002, the MaCWAVE-MIDAS Rocket Program was launched from Andoya Rocket Range (ARR) in Norway. Data from these flights demonstrated that the polar summer mesosphere during this period was unusual, at least above ARR. Theoretical studies have since been published that imply that the abnormal characteristics of this polar summer were generated by dynamical processes occurring in the southern polar winter hemisphere. We have used data from the SABER instrument aboard the NASA Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) Satellite to study these characteristics and compare them with the features observed in the ensuing eight years. For background, the TIMED Satellite was launched on December 7,2001 to study the dynamics and energy of the mesosphere and lower thermosphere. The SABER instrument is a limb scanning infrared radiometer designed to measure temperature of the region as well as a large number of minor constituents. In this study, we review the MaCWAVE rocket results. Next, we investigate 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). Weekly averages are used to make comparisons between the winter and summer hemispheres. Furthermore, the data analysis agrees with recent theoretical studies showing that this behavior is a result of anomalous dynamical events in the southern hemisphere. The findings discussed here clearly show the value of scientific rocket flights used in a discovery mode.

  18. Mesospheric sodium airglow emission: Modeling and first results over a mid-latitude

    NASA Astrophysics Data System (ADS)

    Bag, Tikemani; Krishna, M. V. Sunil; Singh, Vir

    2016-07-01

    Atmospheric sodium plays a very important role in the mesospheric chemistry and dynamics. We have developed a comprehensive model for mesospheric/thermospheric sodium airglow emission by incorporating all the known reaction mechanisms. The latest reaction rate coefficients and the related cross sections are obtained from the theoretical studies and experimental observations. The continuity equations are explicitly solved for the major species. Similarly, the steady-state approximation has been used for the intermediate and short lived minor species. The number densities from in-situ observations, NRLMSISE-00, and IRI-2012 have been successfully implemented to calculate the vertical volume emission rate. The modeled results compared to a good agreement with the measured profiles of Na airglow emission. The mesospheric sodium density shows a large day-to-day variability. The observed variations in the mesospheric sodium layer have been incorporated to obtain the variations in the sodium airglow intensities. The nocturnal variation of sodium airglow emissions are presented over a mid latitude location using this model.

  19. Solar and chemical reaction-induced heating in the terrestrial mesosphere and lower thermosphere

    NASA Technical Reports Server (NTRS)

    Mlynczak, Martin G.

    1992-01-01

    Airglow and chemical processes in the terrestrial mesosphere and lower thermosphere are reviewed, and initial parameterizations of the processes applicable to multidimensional models are presented. The basic processes by which absorbed solar energy participates in middle atmosphere energetics for absorption events in which photolysis occurs are illustrated. An approach that permits the heating processes to be incorporated in numerical models is presented.

  20. Characterization of Dusty Plasmas in the Earth's Mesosphere Using Radiowave Heating

    SciTech Connect

    Scales, Wayne; Chen, Chen

    2008-09-07

    Recently it has become evident that significant diagnostic information may be available to characterize charged sub-visible mesospheric dust layers from the temporal behavior of the associated electron irregularities during radiowave heating which ultimately modifies the mesospheric electron temperature. Particularly important time periods of the irregularity temporal behavior are during the turn-on and turn-off of the radio wave heating. The objective of this work is to first consider the physical processes that control the evolution of electron irregularities associated with mesospheric dust layers during radio wave heating. It is shown that two dominant processes are dust charging and ambipolar diffusion. In particular, 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. Both computational and analytical models are described that may be used to directly investigate the electron irregularity temporal evolution with particular emphasis placed on modeling the electron irregularity temporal evolution during the time periods when the radio wave heating is turned on and off. The models results may then be used to obtain diagnostic information on the characteristics of the charged dust layer, such as dust density and radius. Predictions of the models are used to describe possibilities for new experiments that may provide further diagnostic information on charged mesospheric dust layers.

  1. Mesospheric CO2 clouds at Mars: 6 Martian years of survey by OMEGA/MEx.

    NASA Astrophysics Data System (ADS)

    Gondet, B.; Bibring, JP.; Vincendon, M.

    2014-04-01

    Mesospheric clouds have been detected first from Earth (Bell et al 1996 [1]), then from Mars orbit (MGS/TES and MOC, Clancy et al 1998 [2]). Their composition (CO2) was inferred from temperature. Similar detection and temperature-inferred composition was then performed by SPICAM and PFS on board Mars Express (Montmessin et al., 2006 [3]; Formisano et al.,2006 [4]).

  2. Investigating gravity waves and mesospheric temperature variability over the Andes Mountains

    NASA Astrophysics Data System (ADS)

    Taylor, M. J.; Pautet, P.; Zhao, Y.; Pugmire, J.; Criddle, N.; Swenson, G. R.; Liu, A. Z.; Hecht, J. H.

    2011-12-01

    The Andes region provides an excellent natural laboratory for investigating gravity wave influences on the Upper Mesospheric and Lower Thermospheric (MLT) dynamics with dominant gravity wave forcing expected from deep convection during the summer months replaced by strong orographic forcing during the wintertime, due to intense prevailing zonal winds blowing over the towering Andes mountain range. The instrument suite that comprised the very successful Maui-MALT program (2000-2005) was relocated to a new Andes Lidar Observatory (ALO) located high in the Andes mountains (2,520 m) at Cerro Pachon, Chile (30.3°S, 70.7°W). As part of this instrument set the Utah State University (USU) Mesospheric Temperature Mapper (MTM) has operated continuously over the past two years (August 2009-to date) measuring the nocturnal near infrared OH(6,2) band and the O2(0,1) Atmospheric band intensity and temperature perturbations to investigate a broad range of mesospheric wave forcings, their seasonal variability and effects on the MLT environment over the Andes. This presentation focuses on the strong variability observed from this site using collaborative investigations of selected wave events, including exceptionally large tidal perturbations (70-100 K), unusual "jumps" in OH/O2 temperature possibly associated with wave breaking, mesospheric bore events, and new evidence for quasi-stationary gravity waves, all illustrating the strong wave activity and its diversity over the Andes.

  3. Lasers and the Dynamic Mesosphere/Thermosphere of Venus

    NASA Technical Reports Server (NTRS)

    Kostiuk, Theodor; Fast, Kelly E.; Livengood, Timothy A.; Schmuelling, Frank; Hewagama, Tilak; Annen, John; Buhl, David; Sonnabend, Guido; Sornig, Manuela; Kroetz, Peter; Goldstein, Jeffrey

    2010-01-01

    A review of ground based mid-infrared uniquely high spectral. resolution measurements of Venus dynamics, temperature, and chemistry will be presented. The described studies will focus on the use of CO2 absorption features and the discovery- and use of CO2 thermospheric non-thermal emission: lines as probes of Venus' atmosphere, from the cloud tops to approx.120 km in the thermosphere. The first investigations using infrared heterodyne spectroscopy with resolving power lambda/Delta(lambda) approx. 10(exp 6) to measure true emission line profiles and to determine their non-thermal nature and lasing component will be described. The use of the thermospheric non-thermal CO2 emission to directly measure sub-solar to anti-solar winds and zonal circulation near 110 km altitudes on Venus to approx.2 m/s accuracy will also be described. The measured emission lures are also used to obtain global maps of mesospheric/thermospheric kinetic and rotational temperatures as well as to obtain evidence of the natural lasing phenomena. Carbon dioxide absorption features globally probe lower altitudes in the atmosphere and can be used to determine nightside temperatures. Isotopic 13 CO2 absorption lines are used to probe deeper in the atmosphere to measure the sub-solar to anti-solar return flow at altitudes just above the cloud tops. These results provided a model for global circulation in the 65 - 120 km altitude region first proposed by Goldstein (1989, PhD.Thesis, U. Pennsylvania, Philadelphia, USA). Results of similar wind and temperature measurements made in recent years will be compared to earlier results to investigate changes in the circulation and temperatures since approx.1990. The high resolution infrared heterodyne technique was also used to investigate chemical processes above the cloud tops, specifically evidence and constraints on oxygen-based chemistry. Described measurements were made by infrared heterodyne spectroscopy using the Goddard Space Flight Center Infrared

  4. Detection of Meteoric Dust in the Mesosphere by the CHAMPS Rockets

    NASA Astrophysics Data System (ADS)

    Robertson, S. H.; Dickson, S.; Horanyi, M.; Sternovsky, Z.; Friedrich, M.; Janches, D.; Williams, B.

    2012-12-01

    In October 2011, two CHAMPS (charge and mass of meteoric smoke particles) sounding rockets were launched into the polar mesosphere, each carrying an electrostatic multichannel mass analyzer for charged aerosol particles. The payloads also carried Faraday rotation antennas and an array of plasma probes for determining electron and ion densities and the payload charging potential. The launches were from the Andøya Rocket Range, Norway, following the end of the noctilucent cloud season. One night launch (11 October 21:50 UT) and one day launch (13 October 13:50 UT) helped to elucidate the role of photo-detachment and photoelectric charging. Charge layers in two distinct altitude ranges were observed on both flights: a high altitude negative charge layer between 77 - 93 km, and low altitude positive and negative charge layers that coexist from 63 - 73 km. In a layer spanning approximately 77 - 93 km, the nighttime data show negatively charged particles with masses in the range 500 - 2,000 amu, 2,000 - 8,000 amu and 8,000 - 20,000 amu. These mass ranges occur together each with a particle density of ~400 cm-3. In this altitude range, the Faraday rotation data show that the electron density rises from about 103 cm-3 to about 105 cm-3 indicating that there are sufficient electrons for the fraction of dust that is charged to be near 100%. This negative layer from 77 - 93 km was also present during the day with approximately the same number density. From about 73 km to 63 km where data acquisition ended, the nighttime data show both positive and negative particles in the 500 - 8,000 amu mass ranges with densities of 2,500 cm-3 and 500 cm-3, respectively. The heavier particles have peak densities at lower altitudes. In this altitude range, the dust densities exceed the electron density. These layers are again present in the daytime data with approximately the same altitude distribution; however, the number densities for the positive particles are reduced by a factor of ~3

  5. Variability of mesospheric water vapor above Bern in relation to the 27-day solar rotation cycle

    NASA Astrophysics Data System (ADS)

    Lainer, Martin; Hocke, Klemens; Kämpfer, Niklaus

    2016-06-01

    Many studies investigated solar-terrestrial responses (thermal state, O3, OH, H2O) with emphasis on the tropical upper atmosphere. In this paper the focus is switched to water vapor in the mesosphere at a mid-latitudinal location. Eight years of water vapor profile measurements above Bern (46.88 ° N / 7.46 ° E) are investigated to study oscillations with the focus on periods between 10 and 50 days. Different spectral analyses revealed prominent features in the 27-day oscillation band, which are enhanced in the upper mesosphere (above 0.1 hPa, ∼ 64 km) during the rising sunspot activity of solar cycle 24. Local as well as zonal mean Aura MLS observations support these results by showing a similar behavior. The relationship between mesospheric water and the solar Lyman-α flux is studied by comparing the similarity of their temporal oscillations. The H2O oscillation is negatively correlated to solar Lyman-α oscillation with a correlation coefficient of up to - 0.3 to - 0.4, and the phase lag is 6-10 days at 0.04 hPa. The confidence level of the correlation is ≥ 99 %. This finding supports the assumption that the 27-day oscillation in Lyman-α causes a periodical photodissociation loss in mesospheric water. Wavelet power spectra, cross-wavelet transform and wavelet coherence analysis (WTC) complete our study. More periods of high common wavelet power of H2O and solar Lyman-α are present when amplitudes of the Lyman-α flux increase. Since this is not a measure of physical correlation a more detailed view on WTC is necessary, where significant (two sigma level) correlations occur intermittently in the 27 and 13-day band with variable phase lock behavior. Large Lyman-α oscillations appeared after the solar superstorm in July 2012 and the H2O oscillations show a well pronounced anti-correlation. The competition between advective transport and photodissociation loss of mesospheric water vapor may explain the sometimes variable phase relationship of mesospheric H2

  6. Four Years of Simultaneous Observations of Noctilucent Clouds and Mesospheric Summer Echoes at a Mid-Latitude Site (Kühlungsborn/Germany, 54°N)

    NASA Astrophysics Data System (ADS)

    Gerding, M.; Zoellner, J.; Zecha, M.; Luebken, F. J.

    2015-12-01

    Occurrence of ice particles in the polar summer mesopause region is an intriguing phenomenon that can be observed either optically as Noctilucent Clouds (NLC) / Polar Mesospheric Clouds (PMC) or by radar as (Polar) Mesosphere Summer Echoes ((P)MSE). The relation of both phenomena is well understood and allows insights into atmospheric properties like temperature, humidity, winds, turbulence and electron density. Simultaneous observations of NLC and PMSE require sufficient electron density (for the radar observation) and therefore daylight conditions that may hinder optical observations by lidar. Up to now, simultaneous observations of NLC and PMSE are mainly limited to polar latitudes, while data from mid-latitudes are lacking. Since 2010 we operate a new RMR lidar at our site at Kühlungsborn/Germany (54°N, 12°E). From the best of our knowledge this lidar allows for the first time observations of mid-latitude NLC independent of solar elevation, i.e. during night and day. With our new RMR lidar and the co-located OSWIN radar we are for the first time able to compare the occurrence and altitude structure of NLC and MSE at mid-latitudes. It turns out that the lower edges of simultaneously observed NLC/MSE typically agree, as expected from higher latitudes. Though, the top edge of MSE is observed about 500 m above the NLC edge, indicating the presence of particles being too small to be observed by lidar. Nevertheless, height difference is small compared to the typical layer widths and smaller than observed at higher latitudes. This hints at different size distributions and, by this, different growing conditions at mid-latitudes. We will present a statistical overview on the comparison of simultaneously observed NLC and MSE layers and their main characteristics. Simultaneous NLC and MSE are of additional importance if observed during twilight conditions. The onset or disappearance of MSE during morning and evening twilight is directly related with changing electron

  7. Sensitivity Analysis for Characterizing the Accuracy and Precision of JEM/SMILES Mesospheric O3

    NASA Astrophysics Data System (ADS)

    Esmaeili Mahani, M.; Baron, P.; Kasai, Y.; Murata, I.; Kasaba, Y.

    2011-12-01

    The main purpose of this study is to evaluate the Superconducting sub-Millimeter Limb Emission Sounder (SMILES) measurements of mesospheric ozone, O3. As the first step, the error due to the impact of Mesospheric Temperature Inversions (MTIs) on ozone retrieval has been determined. The impacts of other parameters such as pressure variability, solar events, and etc. on mesospheric O3 will also be investigated. Ozone, is known to be important due to the stratospheric O3 layer protection of life on Earth by absorbing harmful UV radiations. However, O3 chemistry can be studied purely in the mesosphere without distraction of heterogeneous situation and dynamical variations due to the short lifetime of O3 in this region. Mesospheric ozone is produced by the photo-dissociation of O2 and the subsequent reaction of O with O2. Diurnal and semi-diurnal variations of mesospheric ozone are associated with variations in solar activity. The amplitude of the diurnal variation increases from a few percent at an altitude of 50 km, to about 80 percent at 70 km. Although despite the apparent simplicity of this situation, significant disagreements exist between the predictions from the existing models and observations, which need to be resolved. SMILES is a highly sensitive radiometer with a few to several tens percent of precision from upper troposphere to the mesosphere. SMILES was developed by the Japanese Aerospace eXploration Agency (JAXA) and the National Institute of Information and Communications Technology (NICT) located at the Japanese Experiment Module (JEM) on the International Space Station (ISS). SMILES has successfully measured the vertical distributions and the diurnal variations of various atmospheric species in the latitude range of 38S to 65N from October 2009 to April 2010. A sensitivity analysis is being conducted to investigate the expected precision and accuracy of the mesospheric O3 profiles (from 50 to 90 km height) due to the impact of Mesospheric Temperature

  8. Variability of mesospheric water vapor above Bern in relation to the 27-day solar rotation cycle

    NASA Astrophysics Data System (ADS)

    Lainer, Martin; Hocke, Klemens; Kämpfer, Niklaus

    2016-04-01

    We investigate the solar-terrestrial response of mesospheric water vapor from a mid-latitudinal observation site at the 27-day solar rotation cycle time scale. Eight years of water vapor profile measurements above Bern (46.88°N/7.46°E) by the microwave radiometer MIAWARA are used to study prominent oscillation features. The spectral data analyses shows enhanced oscillations in the 27-day period band above 0.1hPa during the rising sunspot activity of solar cycle 24. Aura MLS observations of H2O support these results by showing a similar behavior. The relationship between mesospheric H2O and the solar Lyman-α flux (FLyα) is studied by comparing the similarity of their temporal oscillations. The H2O oscillation is negatively correlated to FLyα oscillation with a correlation coefficient of up to -0.3 to -0.4, and the phase lag is 6-10 days on 0.04hPa. The confidence level of the correlation is ≥ 99%. Additionally we compute wavelet power spectra, cross-wavelet transform and wavelet coherence (WTC). The latter shows significant (two σ level) correlations occurring intermittently in the 27 and 13-day band with variable phase lock behavior. Large FLyα oscillations appeared after the solar superstorm in July 2012 and the H2O oscillations show a well pronounced anti-correlation. The competition between advective transport and photo-dissociation loss of mesospheric H2O may explain the sometimes variable phase relationship of mesospheric H2O and FLyα oscillations. Generally, the WTC analysis indicates that solar variability causes observable photochemical and dynamical processes in the mid-latitude mesosphere.

  9. Is chemical heating a major cause of the mesosphere inversion layer?

    NASA Technical Reports Server (NTRS)

    Meriwether, John W.; Mlynczak, Martin G.

    1995-01-01

    A region of thermal enhancement of the mesosphere has been detected on numerous occasions by in situ measurements, remote sensing from space, and lidar techniques. The source of these 'temperature inversion layers' has been attributed in the literature to the dissipation relating to dynamical forcing by gravity wave or tidal activity. However, evidence that gravity wave breaking can produce the inversion layer with amplitude as large as that observed in lidar measurements has been limited to results of numerical modeling. An alternative source for the production of the thermal inversion layer in the mesosphere is the direct deposition of heat by exothermic chemical reactions. Two-dimensional modeling combining a comprehensive model of the mesosphere photochemistry with the dynamical transport of long-lived species shows that the region from 80 to 95 km may be heated as much as 3 to 10 K/d during the night and half this rate during the day. Given the uncertainties in our understanding of the dynamics and chemistry for the mesopause region, separating the two sources by passive observations of the mesosphere thermal structure looks to be difficult. Therefore we have considered an active means for producing a mesopause thermal layer, namely the release of ozone into the upper mesosphere from a rocket payload. The induced effects would include artificial enhancements of the OH and Na airglow intensities as well as the mesopause thermal structure. The advantages of the rocket release of ozone is that detection of these effects by ground-based imaging, radar, and lidar systems and comparison of these effects with model predictions would help quantify the partition of the artificial inversion layer production into sources of dynamical and chemical forcing.

  10. Detection of Long-Term Temperature Changes in the Stratosphere and Mesosphere

    NASA Astrophysics Data System (ADS)

    Yee, J.; Swartz, W. H.; Mlynczak, M. G.; Russell, J. M.

    2010-12-01

    Over the past five decades, temporal and spatial changes in the Earth's Stratosphere and Mesosphere have been documented by measurements by numerous rocket/satellite borne and groundbased in-situ and remote sensing instruments. These datasets have allowed us to gain physical insights into processes that control the observed changes through high-fidelity physics-based first-principle models. These processes, although being complex because of their mutual coupling nature, they, however, can generally be attributed to two distinct origins: the Sun above and the human below. NASA'S Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics (TIMED) mission, over the past eight and half years, has provided an excellent quantitative description of the upper atmosphere variabilities. Its observations, covering near an entire solar cycle, along with other worldwide network of groundbased and satellite observations of the stratosphere/mesosphere/thermosphere/ ionosphere system have transformed our understanding of this gateway region of near-Earth space by successfully characterizing its physics, dynamics, energetics, composition and thermal structures in the context of solar induced variabilities. It is clear that without measurements in at least one or more solar cycle, it is impossible to separate out the relative effects of solar driving, inter-annual lower atmosphere variability, and the long-term human-induced changes. Combining measurements covering several solar cycles are clearly needed. However, these measurements have generally been taken by different sensors on different platforms using different sensing techniques. In this paper, we will present nearly three decades of stratospheric and mesospheric temperature measurements from LIMS, HALOE/UARS, MLS/UARS, SABER/TIMED, COSMIC, CHAMP, MLS/Aura, and assess their measurement qualities for decadal-scale temperature change studies. The systematic measurement biases among these datasets will be documented, and

  11. On the Observed Changes in Upper Stratospheric and Mesospheric Temperatures from UARS HALOE

    NASA Technical Reports Server (NTRS)

    Remsberg, Ellis E.

    2006-01-01

    Temperature versus pressure or T(p) time series from the Halogen Occultation Experiment (HALOE) on the Upper Atmosphere Research Satellite (UARS) have been extended and re-analyzed for the period of 1991-2005 and for the upper stratosphere and mesosphere in 10-degree wide latitude zones from 60S to 60N. Even though sampling from a solar occultation experiment is somewhat limited, it is shown to be quite adequate for developing both the seasonal and longer-term variations in T(p). Multiple linear regression (MLR) techniques were used in the re-analyses for the seasonal and the significant interannual, solar cycle (SC-like or decadal-scale), and linear trend terms. A simple SC-like term of 11-yr period was fitted to the time series residuals after accounting for the seasonal and interannual terms. Highly significant SC-like responses were found for both the upper mesosphere and the upper stratosphere. The phases of these SC-like terms were checked for their continuity with latitude and pressure-altitude, and in almost all cases they are directly in-phase with that of standard proxies for the solar flux variations. The analyzed, max minus min, responses at low latitudes are of order 1 K, while at middle latitudes they are as large as 3 K in the upper mesosphere. Highly significant, linear cooling trends were found at middle latitudes of the middle to upper mesosphere (about -2 K/decade), at tropical latitudes of the middle mesosphere (about -1 K/decade), and at 2 hPa (or order -1 K/decade).

  12. Aura Microwave Limb Sounder observations of the polar middle atmosphere: Dynamics and transport of CO and H2O

    NASA Astrophysics Data System (ADS)

    Lee, Jae N.; Wu, Dong L.; Manney, Gloria L.; Schwartz, Michael J.; Lambert, Alyn; Livesey, Nathaniel J.; Minschwaner, Kenneth R.; Pumphrey, Hugh C.; Read, William G.

    2011-03-01

    The vertical structure and evolution of the wintertime annular modes are studied using 6 years of geopotential height, carbon monoxide (CO), and water vapor (H2O) data from Aura Microwave Limb Sounder. The Northern Hemisphere annular mode (NAM) and the Southern Hemisphere annular mode (SAM) reveal a strong coupling of the dynamics in the stratosphere and mesosphere between 316 hPa (˜9 km) and 0.002 hPa (˜90 km). CO is a good tracer throughout the middle atmosphere, while variable vertical gradients of H2O limit the regions where it is useful as a dynamical tracer. The maximum of the CO NAM and SAM (CNAM and CSAM) indices is used to monitor and characterize the evolution of wintertime polar dynamics as a function of time and height. The CNAM analysis reveals reformation of a stronger mesospheric polar vortex after significant stratospheric sudden warmings in 2006, 2009, and 2010. There is a significant anticorrelation between the mesospheric and stratospheric CNAM indices during 2005-2010 winters, supporting the hypothesis of mesosphere-stratosphere coupling through planetary-gravity wave interactions.

  13. The seasonal variation of water vapor and ozone in the upper mesosphere - Implications for vertical transport and ozone photochemistry

    NASA Technical Reports Server (NTRS)

    Bevilacqua, Richard M.; Summers, Michael E.; Strobel, Darrell F.; Olivero, John J.; Allen, Mark

    1990-01-01

    This paper reviews the data base supplied by ground-based microwave measurements of water vapor in the mesosphere obtained in three separate experiments over an eight-year period. These measurements indicate that the seasonal variation of water vapor in the mesosphere is dominated by an annual component with low values in winter and high values in summer, suggesting that the seasonal variation of water vapor in the mesosphere (below 80 km) is controlled by advective rather than diffusive processes. Both the seasonal variation and the absolute magnitude of the water vapor mixing ratios obtained in microwave measurements were corroborated by measurements obtained in the Spacelab GRILLE and ATMOS experiments, and were found to be consistent with several recent mesospheric dynamics studies.

  14. High resolution mesospheric sodium properties for adaptive optics applications

    NASA Astrophysics Data System (ADS)

    Pfrommer, T.; Hickson, P.

    2014-05-01

    Context. The performance of laser guide star adaptive optics (AO) systems for large optical and infrared telescopes is affected by variability of the sodium layer, located at altitudes between 80 and 120 km in the upper mesosphere and lower thermosphere. The abundance and density structure of the atomic sodium found in this region is subject to local and global weather effects, planetary and gravity waves and magnetic storms, and is variable on time scales down to tens of milliseconds, a range relevant to AO. Aims: It is therefore important to characterize the structure and dynamical evolution of the sodium region on small, as well as large spatial and temporal scales. Parameters of particular importance for AO are the mean sodium altitude, sodium layer width and the temporal power spectrum of the centroid altitude. Methods: We have conducted a three-year campaign employing a high-resolution lidar system installed on the 6-m Large Zenith Telescope (LZT) located near Vancouver, Canada. During this period, 112 nights of useful data were obtained. Results: The vertical density profile of atomic sodium shows remarkable structure and variability. Smooth Gaussian-shaped profiles rarely occur. Multiple internal layers are frequently found. These layers often have sharp lower edges, with scale heights of just a few hundred meters, and tend to drift downwards at a typical rate of one kilometer every two to three hours. Individual layers can persist for many hours, but their density and internal structure can be highly variable. Sporadic layers are seen reaching peak densities several times the average, often in just a few minutes. Coherent vertical oscillations are often found, typically extending over tens of kilometers in altitude. Regions of turbulence are evident and Kelvin-Helmholtz instability are sometimes seen. The mean value of the centroid altitude is found to be 90.8 ± 0.1 km. The sodium layer width was determined by computing the altitude range that contains a

  15. The detached haze layer in Titan's mesosphere: The formation process

    NASA Astrophysics Data System (ADS)

    Lavvas, P.; Yelle, R. V.; Vuitton, V.

    2008-09-01

    Cassini observations made by the Imaging Science Subsystem (ISS) [1] and by the UltraViolet Imaging Spectrometer (UVIS) [2,3] have revealed the presence of a detached haze layer in Titan's mesosphere at an altitude of 520 km. Analysis of the observed optical properties presented in the accompanying talk [5], suggests that the average size of particles in the detached layer is of ~40 nm, with an imaginary index k < 0.3 at 187.5 nm and a number density of ˜30 particles cm-3, while calculations of the sedimentation velocity of the haze 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 main haze layer in Titan's stratosphere is formed primarily by sedimentation and coagulation of particles in the detached layer [5,6]. The HASI data clearly show that the haze is coincident with a temperature maximum. This rules out condensation as the source of the detached haze. We have also considered a more complicated scenario in which the detached layer is caused by an increase in the density of condensation nuclei near 520 km. This is motivated by the fact that silicate micrometeorites ablate near 500 km [7,8]. Recondensation of the refractory vapor creates `smoke' particles that could serve as condensation nuclei. Combination of Pioneer measurements along with theoretical estimations for the particles velocity distribution, suggest a mass flux of ~10-17 g cm-2 s-1 at Saturn's region [9], while measurements from the Cassini Dust Analyser (CDA) suggest a similar magnitude at Titan's location [10]. These fluxes are ~3 orders of magnitude smaller than the lower limit of the estimated mass flux out of the detached haze layer, so meteorite ablation can not be the direct cause of the aerosol layer. However, if the ablated meteoritic material reforms 1 nm particles, the implied number flux would be 2.4 × 103 particles cm-2 s-1

  16. The thermal and dynamical state of the Antarctic mesopause region during winter/summer transition and the role of stratosphere/mesosphere coupling

    NASA Astrophysics Data System (ADS)

    Luebken, F. J.; Höffner, J.; Viehl, T. P.; Latteck, R.; Becker, E.; Kaifler, B.; Murphy, D. J.; Morris, R.

    2015-12-01

    The transition of stratospheric circulation at Antarctic latitudes from winter to summer conditions is highly variably from year to year. As has been realized recently, this also affects the winter/summer transition at mesopause altitudes. The Antarctic middle atmosphere therefore offers the unique possibility to study the physical processes involved in the vertical coupling between the stratosphere and the mesosphereduring winter/summer transition, in particular the role of gravity waves. We present new results from the mobile scanning iron lidar of the Leibniz Institute of Atmospheric Physics in Kühlungsborn (IAP) which was in operation at Davis, Antarctica, from December 15, 2010, until December 31, 2012. It measured temperatures in the iron layer (~80-100 km). The lidar can operate under daylight conditions. 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 and compare with circulation changes in the stratosphere derived from MERRA. We also compare with the northern hemisphere (NH). 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 altitudechanges 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. We studied the seasonal variation of polar mesosphere summer echoes (PMSE). PMSE are strong radar echoes related to ice particles and therefore require very low atmospheric temperatures. The VHF radar frequently detected PMSE. We compare the seasonal

  17. A compact receiver system for simultaneous measurements of mesospheric CO and O3

    NASA Astrophysics Data System (ADS)

    Forkman, P.; Christensen, O. M.; Eriksson, P.; Billade, B.; Vassilev, V.; Shulga, V. M.

    2016-02-01

    During the last decades, ground-based microwave radiometry has matured into an established remote sensing technique for measuring vertical profiles of a number of gases in the stratosphere and the mesosphere. Microwave radiometry is the only ground-based technique that can provide vertical profiles of gases in the upper stratosphere and mesosphere both day and night, and even during cloudy conditions. Except for microwave instruments placed at high-altitude sites, or at sites with dry atmospheric conditions, only molecules with significant emission lines below 150 GHz, such as CO, H2O, and O3, can be observed. Vertical profiles of these molecules can give important information about chemistry and dynamics in the middle atmosphere. Today these measurements are performed at relatively few sites; more simple and reliable instrument solutions are required to make the measurement technique more widely spread. This need is urgent today as the number of satellite sensors observing the middle atmosphere is about to decrease drastically. In this study a compact double-sideband frequency-switched radiometer system for simultaneous observations of mesospheric CO at 115.27 GHz and O3 at 110.84 GHz is presented. The radiometer, its calibration scheme, and its observation method are presented. The retrieval procedure, including compensation of the different tropospheric attenuations at the two frequencies and error characterization, are also described. The first measurement series from October 2014 until April 2015 taken at the Onsala Space Observatory, OSO (57° N, 12° E), is analysed. The retrieved vertical profiles are compared with co-located CO and O3 data from the MLS instrument on the Aura satellite. The data sets from the instruments agree well with each other. The main differences are the higher OSO volume mixing ratios of O3 in the upper mesosphere during the winter nights and the higher OSO volume mixing ratios of CO in the mesosphere during the winter. The low bias

  18. A~compact receiver system for simultaneous measurements of mesospheric CO and O3

    NASA Astrophysics Data System (ADS)

    Forkman, P.; Christensen, O. M.; Eriksson, P.; Billade, B.; Vassilev, V.; Shulga, V. M.

    2015-09-01

    During the last decades, ground-based microwave radiometry has matured to an established remote sensing technique for measuring vertical profiles of a number of gases in the stratosphere and the mesosphere. Microwave radiometry is the only ground-based technique that can provide vertical profiles of gases in the upper stratosphere and mesosphere both day and night, and even during cloudy conditions. Except for microwave instruments placed at high altitude sites, or at sites with dry atmospheric conditions, only molecules with significant emission lines below 150 GHz, such as CO, H2O and O3 can be observed. Vertical profiles of these molecules can give important information about chemistry and dynamics in the middle atmosphere. Today these measurements are performed at relatively few sites, more simple and reliable instrument solutions are required to make the measurement technique more widely spread. This need is today urgent as the number of satellite sensors observing the middle atmosphere is about to decrease drastically. In this study a compact double-sideband frequency-switched radiometer system for simultaneous observations of mesospheric CO at 115.27 GHz and O3 at 110.84 GHz is presented The radiometer, its calibration scheme and observation method are presented. The retrieval procedure, including compensation of the different tropospheric attenuation at the two frequencies, and error characterization are also described. The first measurement series from October 2014 until April 2015 taken at the Onsala Space Observatory, OSO, (57° N, 12° E) is analysed. The retrieved vertical profiles are compared with co-located CO and O3 data from the MLS instrument on the Aura satellite. The datasets from the instruments agree well to each other. The main differences are the higher OSO volume mixing ratios of O3 in the upper mesosphere during the winter nights and the higher OSO volume mixing ratios of CO in the mesosphere during the winter. The low bias of mesospheric

  19. Development of a stratospheric and mesospheric microwave temperature sounder experiment

    NASA Technical Reports Server (NTRS)

    Staelin, D. H.; Rosenkranz, P. W.; Anderson, B. G.; Kunzi, K. F.; Paroskie, R. M.; Parr, R. J.; Waters, J. W.

    1975-01-01

    A passive microwave spectrometer system for measuring global atmospheric temperature profiles from 0-75 km altitude was developed and analyzed. The system utilizes 12 channels near the 5 mm wavelength oxygen absorption band and is designed to provide global coverage by scanning perpendicular to the orbital track of a polar orbiting satellite. A significant improvement in the accuracy of theoretical atmospheric microwave transmittance functions was achieved through the development of a first-order approximation to overlapping line theory for the oxygen molecule. This approximation is particularly important in the troposphere and lower stratosphere where pressure-broadening blends nearby lines. Ground-based and aircraft observations of several resonances of stratospheric oxygen generally support the theory. The 23, 25, 29, and 31 atmospheric oxygen lines were measured and the frequencies of several such oxygen lines were measured with improved precision. The polarization and Zeeman splitting of the atmospheric 27 line was also observed.

  20. On the seasonal variations of reflectivity and turbulence characteristics of low-latitude mesospheric echoes over Gadanki

    NASA Astrophysics Data System (ADS)

    Selvaraj, D.; Patra, A. K.; Narayana Rao, D.

    2016-06-01

    Gadanki radar observations of the low-latitude mesospheric echoes studied earlier have shown that while both occurrence rate and signal-to-noise ratio of the mesospheric echoes peak in the equinoxes turbulent kinetic energy (TKE) dissipation rate and eddy diffusivity, estimated using spectral width of these echoes, peak in the summer. This seasonal difference is apparently inconsistent with the understanding that the mesospheric echoes are generated by turbulence. In this paper, we analyze Gadanki radar observations of mesospheric echoes made during 2011 and 2012 and study seasonal variations in reflectivity and TKE dissipation rate in an attempt to address the aforementioned puzzle. We show that both reflectivity and TKE dissipation rate in the mesosphere show semiannual variations peaking in the equinoxes, which are vastly different from those reported earlier. We also show that seasonal variations in reflectivity and TKE dissipation rate have a close correspondence with gravity wave activity. These results are found to be consistent with the gravity wave breaking hypothesis generating turbulence and radar echoes in the low-latitude mesosphere.

  1. Observation and Modeling of Mesospheric Frontal Events, Bores, and Nonlinear Waves

    NASA Astrophysics Data System (ADS)

    Picard, R. H.; Taylor, M. J.; Dewan, E. M.; Seo, S. H.; Cohen, E.; Winick, J. R.

    2003-12-01

    We describe and categorize observations of mesospheric frontal events in OH Meinel and atomic-oxygen green-line airglows from mid- and low-latitude sites. Such extensive and long-lasting displays were first observed by Taylor and co-workers in the ALOHA-93 Campaign and attributed by Dewan and Picard to the existence of an internal-wave undular bore, a transient phase motion in a mesospheric wave duct. Prior observations of internal-wave bores had been made on ducts in the atmospheric boundary layer and the upper ocean, and such disturbances have been found to develop into solitons under certain conditions. We examine how wave ducts supporting bores can be formed by atmospheric temperature and wind structure near the mesopause and carry out calculations of the dynamics of bore propagation and of the airglow response, comparing the result of calculations to the observations.

  2. Observation and modeling of mesospheric frontal events, bores, and nonlinear waves

    NASA Astrophysics Data System (ADS)

    Picard, R. H.; Taylor, M. J.; Dewan, E. M.; Seo, S. H.; Cohen, E.

    2003-04-01

    We describe and categorize observations of mesospheric frontal events in OH Meinel and atomic-oxygen green-line airglow layers from mid- and low-latitude sites. Such extensive and long-lasting displays were first observed by Taylor and co-workers in the ALOHA-93 Campaign and attributed by Dewan and Picard to the existence of an internal-wave undular bore, a transient phase motion in a mesospheric wave duct. Prior observations of internal-wave bores had been made on ducts in the atmospheric boundary layer and the upper ocean, and such disturbances have been found to develop into solitons under certain conditions. We examine how wave ducts supporting bores can be formed by the atmospheric temperature and wind structure near the mesopause and carry out calculations of the dynamics of bore propagation and of the airglow response, comparing the result of calculations to the observations.

  3. Mesospheric gravity waves and ionospheric plasma bubbles observed during the COPEX campaign

    NASA Astrophysics Data System (ADS)

    Paulino, I.; Takahashi, H.; Medeiros, A. F.; Wrasse, C. M.; Buriti, R. A.; Sobral, J. H. A.; Gobbi, D.

    2011-07-01

    During the Conjugate Point Experiment (COPEX) campaign performed at Boa Vista (2.80∘N;60.70∘W, dip angle21.7∘N) from October to December 2002, 15 medium-scale gravity waves in the OHNIR airglow images were observed. Using a Keogram image analysis, we estimate their parameters. Most of the waves propagate to Northwest, indicating that their main sources are Southeast of Boa Vista. Quasi-simultaneous plasma bubble activities in the OI 630 nm images were observed in seven cases. The distances between the bubble depletions have a linear relationship with the wavelengths of the gravity waves observed in the mesosphere, which suggests a direct contribution of the mesospheric medium-scale gravity waves in seeding the equatorial plasma bubbles.

  4. Some aspects of metallic ion chemistry and dynamics in the mesosphere and thermosphere

    NASA Technical Reports Server (NTRS)

    Mathews, J. D.

    1987-01-01

    The relationship between the formation of sporadic layers of metallic ion and the dumping of these ions into the upper mesosphere is discussed in terms of the tidal wind, classical (i.e., windshear) and other more complex, perhaps highly nonlinear layer formation mechanisms, and a possible circulation mechanism for these ions. Optical, incoherent scatter radar, rocket, and satellite derived evidence for various layer formation mechanisms and for the metallic ion circulation system is reviewed. The results of simple one dimensional numerical model calculations of sporadic E and intermediate layer formation are presented along with suggestions for more advanced models of intense or blanketing sporadic E. The flux of metallic ions dumped by the tidal wind system into the mesosphere is estimated and compared with estimates of total particle flux of meteoric origin. Possible effects of the metallic ion flux and of meteoric dust on D region ion chemistry are discussed.

  5. Energy balance in the mesosphere and lower thermosphere as revealed by SABER, SEE, and SORCE

    NASA Astrophysics Data System (ADS)

    Mlynczak, M. G.; Hunt, L. A.; Mast, J. C.; Mertens, C. J.; Marshall, B. T.; Russell, J. M.; Thompson, R. E.; Gordley, L. L.

    2011-12-01

    We examine the annual energy budget of the mesosphere using measurements from the SABER and SEE instruments on the TIMED satellite and from the SORCE satellite. Rates of heating due to absorption of solar radiation by ozone and molecular oxygen, rates of heating due to seven exothermic chemical reactions, and rates of cooling due to infrared emission by carbon dioxide and ozone are presented. A time series of radiative cooling by carbon dioxide in the mesosphere for the past decade is also included. While uncertainties, particularly in the rates of heating by exothermic chemical reactions, place limits on the exact knowledge of these parameters, we can show approximate balance in heating and cooling rates on annual timescales.

  6. Vertical transport and photochemistry in the terrestrial mesosphere and lower thermosphere /50-120 km/

    NASA Astrophysics Data System (ADS)

    Allen, M.; Yung, Y. L.; Waters, J. W.

    1981-05-01

    A study is conducted of the coupled effects of kinetics, solar cycle flux variations, and vertical transport on the distribution of long-lived hydrogen-carbon-oxygen compounds in the terrestrial mesosphere and lower thermosphere, using a one-dimensional aeronomy model. The calculations account for the important chemical reactions and use rocket measurements of the solar flux at solar minimum and maximum. Photodissociation rates appropriate for the mesosphere are determined with a spherical shell atmosphere formalism. Detailed corrections for the O2 Schumann-Runge bands and the temperature dependence of the CO2 cross sections are used. An eddy diffusion profile is derived which is in agreement with the Aladdin 74 mass spectral measurements of atomic O, O2, CO2, and Ar in the lower thermosphere and observations of the O3 minimum at about 80 km.

  7. SABER observations of mesospheric ozone during NH late winter 2002-2009

    NASA Astrophysics Data System (ADS)

    Smith, A. K.; López-Puertas, M.; García-Comas, M.; Tukiainen, S.

    2009-12-01

    Observations from the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) instrument on the TIMED (Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics) satellite show interannual variations of mesospheric ozone in the NH late winter. Ozone in the mid-January to mid-March period is significantly different in 2004, 2006, and 2009 than in other years (2002, 2003, 2005, 2007, 2008). The altitudes of the ozone secondary maximum (˜90-95 km), the minimum (˜80 km) and the tertiary maximum (˜72 km) are all lower by 3-5 km during the three anomalous winters. The ozone anomalies indicate enhanced downward motion and are consistent with other observations of unusual profiles of trace species. The ozone perturbations extend to at least 100 km while temperatures above 90 km are within the range found in the other years.

  8. Heating, ionization and upward discharges in the mesosphere due to intense quasi-electrostatic thundercloud fields

    NASA Technical Reports Server (NTRS)

    Pasko, Victor P.; Inan, Umran S.; Taranenko, Yuri N.; Bell, Timothy F.

    1995-01-01

    Quasi-electrostatic (QE) fields that temporarily exist at high altitudes following the sudden removal (e.g., by a lightning discharge) of thundercloud charge at low altitudes are found to significantly heat mesospheric electrons and produce ionization and light. The intensity, spatial extent, duration and spectra of optical emissions produced are consistent with the observed features of the Red Sprite type of upward discharges.

  9. Strato-mesospheric ozone measurements using ground-based millimeter-wave spectroscopy at Thule, Greenland

    NASA Astrophysics Data System (ADS)

    Muscari, Giovanni; Cesaroni, Claudio; Fiorucci, Irene; Smith, Anne K.; Froidevaux, Lucien; Mlynczak, Martin G.

    2012-04-01

    On January 2009 a ground-based millimeter-wave spectrometer (GBMS) was installed at Thule Air Base (76.5°N, 68.8°W), Greenland, for long-term winter monitoring of several stratospheric and mesospheric trace gases in the framework of the Network for the Detection of Atmospheric Composition Change. This work is aimed at characterizing the GBMS O3 vertical profiles between 35 and 80 km altitude obtained by applying the optimal estimation method to O3pressure-broadened spectral line measurements carried out during three winters. In this altitude range, GBMS O3 retrievals are highly sensitive to variations of the atmospheric state, and their accuracy is estimated to be the larger of 11% or 0.2 ppmv. Comparisons of GBMS O3profiles with colocated satellite-based measurements from Aura Microwave Limb Sounder (MLS) and Thermosphere Ionosphere Mesosphere Energetics and Dynamics Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) show a good agreement below 65 km altitude once the known 10%-20% high bias of SABER O3profiles is considered, with the GBMS displaying an averaged low bias of ˜9% and 17% with respect to MLS and SABER. In the nighttime mesosphere, the GBMS detects the ozone tertiary maximum within 0.1 ppmv (6%) on average with respect to the convolved MLS, SABER, and global 3-D ROSE model profiles but shifts its position to lower altitudes by 4-5 km compared to the height obtained by the other three data sets. In the 50-80 km altitude range, estimates of mesospheric O3 diurnal variation obtained from the GBMS and the convolved satellite measurements agree well within the ±1 standard deviation (˜0.6 ppmv) of the GBMS mean profile.

  10. The Ames two-dimensional stratosphere-mesospheric model. [chemistry and transport of SST pollution

    NASA Technical Reports Server (NTRS)

    Whitten, R. C.; Borucki, W. J.; Watson, V. R.; Capone, L. A.; Maples, A. L.; Riegel, C. A.

    1974-01-01

    A two-dimensional model of the stratosphere and mesosphere has recently been developed at Ames Research Center. The model contains chemistry based on 18 species that are solved for at each step and a seasonally-varying transport model based on both winds and eddy transport. The model is described and a preliminary assessment of the impact of supersonic aircraft flights on the ozone layer is given.

  11. Estimation of stratospheric-mesospheric density fields from satellite radiance data

    NASA Technical Reports Server (NTRS)

    Quiroz, R. S.

    1974-01-01

    Description of a method for deriving horizontal density fields at altitudes above 30 km directly from satellite radiation measurements. The method is applicable to radiation measurements from any instrument with suitable transmittance weighting functions. Data such as those acquired by the Satellite Infrared Spectrometers on satellites Nimbus 3 and 4 are employed for demonstrating the use of the method for estimating stratospheric-mesospheric density fields.

  12. Development of a mesospheric sodium laser beacon for atmospheric adaptive optics. (Reannouncement with new availability information)

    SciTech Connect

    Jeys, T.H.

    1991-12-31

    The authors have developed laser sources of sodium-resonance radiation based on the sum-frequency mixing of Nd:YAG laser radiation. The sources are suitable for generating a fluorescence spot in the earth`s mesospheric sodium layer for use in adaptive optics compensation. Taking into account the sodium fluorescence lifetime, Doppler broadening, hyperfine structure, radiative saturation, optical pumping, and radiation pressure, we can optimize the intensity of the fluorescence by using spectral and temporal tailoring of the laser radiation.

  13. Development of Ultra-Thin Polyethylene Balloons for High Altitude Research upto Mesosphere

    NASA Astrophysics Data System (ADS)

    Kumar, B. Suneel; Nagendra, N.; Ojha, D. K.; Peter, G. Stalin; Vasudevan, R.; Anand, D.; Kulkarni, P. M.; Reddy, V. Anmi; Rao, T. V.; Sreenivasan, S.

    Ever since its inception four decades back, Balloon Facility of Tata Institute of Fundamental Research (TIFR), Hyderabad has been functioning with the needs of its user scientists at its focus. During the early nineties, when the X-ray astronomy group at TIFR expressed the need for balloons capable of carrying the X-ray telescopes to altitudes up to 42 km, the balloon group initiated research and development work on indigenous balloon grade films in various thickness not only for the main experiment but also in parallel, took up the development of thin films in thickness range 5 to 6 μm for fabrication of sounding balloons required for probing the stratosphere up to 42 km as the regular 2000-gram rubber balloon ascents could not reach altitudes higher than 38 km. By the year 1999, total indigenization of sounding balloon manufacture was accomplished. The work on balloon grade ultra-thin polyethylene film in thickness range 2.8 to 3.8 μm for fabrication of balloons capable of penetrating mesosphere to meet the needs of user scientists working in the area of atmospheric dynamics commenced in 2011. Pursuant to the successful trials with 61,000-m3 balloon made of 3.8-μm Antrix film reaching stratopause (48 km) for the first time in the history of balloon facility in the year 2012, fine tuning of launch parameters like percentage free lift was carried out to take the same volume balloons to higher mesospheric altitudes. Three successful flights with a total suspended load of 10 kg using 61,000-m3 balloons were carried out in the month of January 2014 and all the three balloons crossed into the mesosphere reaching altitudes of over 51 km. All the balloons flown so far are closed system with no escape ducts. Balloon fabrication, development of launch hardware, flight control instruments and launch technique for these mesospheric balloon flights are discussed in this paper.

  14. Mesospheric wind measurements using a medium-frequency imaging Doppler interferometer

    NASA Technical Reports Server (NTRS)

    Adams, G. W.; scatterers.

    1986-01-01

    Wind results from a medium-frequency radar operated as an imaging Doppler interferometer are presented. Ten independent antennas, together with mesospheric wind motions, were used to Doppler-sort and then echo-locate individual scattering points. The three-dimensional location and radial velocity of each discrete scattering point was determined. Mean winds were then determined by a least squares fit to the radial velocities of the ensemble of scatterers.

  15. Vertical profile of δ18OOO from the middle stratosphere to lower mesosphere from SMILES spectra

    NASA Astrophysics Data System (ADS)

    Sato, T. O.; Sagawa, H.; Yoshida, N.; Kasai, Y.

    2014-04-01

    Ozone is known to have large oxygen isotopic enrichments of about 10% in the middle stratosphere; however, there have been no reports of ozone isotopic enrichments above the middle stratosphere. We derived an enrichment δ18OOO in the stratosphere and the lower mesosphere from observations of the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) onboard the International Space Station (ISS) using a retrieval algorithm optimized for the isotopic ratio. The retrieval algorithm includes (i) an a priori covariance matrix constrained by oxygen isotopic ratios in ozone, (ii) an optimization of spectral windows for ozone isotopomers and isotopologues, and (iii) common tangent height information for all windows. The δ18OOO by averaging the SMILES measurements at the latitude range of 20 to 40° N from February to March in 2010 with solar zenith angle < 80° was 13% (at 32 km) with the systematic error of about 5%. SMILES and past measurements were in good agreement, with δ18OOO increasing with altitude between 30 and 40 km. The vertical profile of δ18OOO obtained in this study showed an increase and a decrease with altitude in the stratosphere and mesosphere, respectively. The δ18OOO peak, 18%, is found at the stratopause. The δ18OOO has a positive correlation with temperature in the range of 220-255 K, indicating that temperature can be a dominant factor to control the vertical profile of δ18OOO in the stratosphere and mesosphere. This is the first report of the observation of δ18OOO over a wide altitude range extending from the stratosphere to the mesosphere (28-57 km).

  16. The detached haze layer in Titan's mesosphere: observations and analysis

    NASA Astrophysics Data System (ADS)

    Yelle, R. V.; Lavvas, P.; Vuitton, V.

    2008-09-01

    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) [1] 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) [2,3]. 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) [4]. This temperature inversion is also permanent and global, having been detected in several ground-based stellar occultations [5]. The correlation between the extinction profile and temperature profile imply that the detached haze cannot be due to condensation, as previously suggested [3]. Analysis of the observed optical properties (Fig. 2) implies that the average size of particles in the detached layer is <45 nm, with an imaginary index < 0.3 at 187.5 nm. Using the solutions shown in Fig. 2 we calculate the imaginary index, number density, sedimentation velocity, and mass flux for the detached haze. The results are shown in Fig. 3. Non-LTE calculations of the temperature perturbation due to the detached haze show that the average size of the haze particles must be greater than 35 nm or implied heating rates are far too large (Fig. 4). Calculation of a suite of thermal structure models as a function of assumed particle size show that the observed temperature rise implies a mean particle radius greater than 35 nm. Thus, we conclude that the particle radius in the detached layer must be in the 35- 45 nm range. Consideration of sources for the haze also implies larger particle sizes. As shown in Fig. 3, a mean particle radius less than 35 nm implies a mass flux greater

  17. One: Microphysics of frost metamorphism: Applications to Triton and Mars. Two: A global analysis of the ozone deficit in the upper stratosphere and lower mesosphere. Three: The diabatic circulation in the stratosphere as diagnosed from Microwave Limb Sounder data

    SciTech Connect

    Eluszkiewicz, J.B.

    1993-01-01

    The present thesis is devoted to two broad subjects, planetary frost metamorphism and the terrestrial middle atmosphere, and consists of three papers. Paper 1 considers frost metamorphism on the surfaces of Triton and Mars. Based on an analysis of the microphysical processes involved in the pressureless sintering, it is concluded that fine-grained nitrogen and carbon dioxide frosts can undergo seasonal metamorphism into semitransparent layers on the surface of Triton and in the Martian seasonal polar caps, respectively. The presence of such layers explains a host of facts about Triton's surface and about the Martian seasonal caps. Paper 2 is devoted to elucidating a long-standing issue in the terrestrial middle atmosphere chemistry, the so-called 'ozone deficit problem.' Based on an analysis of data acquired by the Limb Infrared Monitor of the Stratosphere (LIMS) instrument between October 1978 and May 1979, it is concluded that current photochemical models systematically underestimate observed ozone abundances in the upper stratosphere and lower mesosphere. Three modifications to the accepted photochemical scheme, capable of providing a global solution to this problem, are proposed and discussed. Paper 3 differs from the other two in that it reports on results from an ongoing research effort. It considers the diabatic circulation in the stratosphere and lower mesosphere, using ozone and temperature measurements acquired by the Microwave Limb Sounder (MLS) instrument onboard the Upper Atmosphere Research Satellite (UARS). The present study extends past analyses of the diabatic circulation by considering a full annual cycle, November 1991-November 1992, and by taking advantage of the high vertical resolution of MLS data. In the tropical upper stratosphere and lower mesosphere, a semiannual oscillation (SAO) is observed in the computed circulation, with the region of downwelling reaching maximum spatial extent approximately 1 month before the equinox.

  18. Comparison of mesospheric VHF radar echoes and rocket probe electron concentration measurements

    NASA Technical Reports Server (NTRS)

    Royrvik, O.; Smith, L. G.

    1984-01-01

    Refractive index irregularities in the equatorial mesosphere have been investigated using both the Jicamarca VHF radar and a rocket-borne Langmuir probe launched from Punta Lobos, Peru. On February 27, 1983, a single layer of turbulence was observed in the upper mesosphere by both experiments. There is very good agreement between the observed radar echo power and the radar scattering cross section calculated from the rocket data when these are interpreted in the context of isotropic turbulence. The inner and outer scales of turbulence have been calculated from both the radar and the rocket data, and good agreement is found. The radar data show indications of large-scale vortices in the layer of irregularities. Rocket data show that the inner scale of turbulence in the upper mesosphere is a few tens of meters and that the Jicamarca radar Bragg wavelength (3 m) is well within the viscous subrange of turbulence in this altitude range. The spectral index in the inertial subrange is close to -5/3, changing to about - 7 at higher wave numbers. Energy dissipation rate in the layer was calculated to be 0.05 W/kg, in good agreement with previous estimates.

  19. Laser Measurements of the H Atom + Ozone Rate Constant at Mesospheric Temperatures.

    PubMed

    Liu, Yingdi; Peng, Jian; Reppert, Kelsey; Callahan, Sara; Smith, Gregory P

    2016-06-01

    The exothermic H + O3 reaction produces OH(v) Meinel band emissions, used to derive mesospheric H concentrations and chemical heating rates. We remeasured its rate constant to reduce its uncertainty and extended the measurements to lower mesospheric temperatures using modern laser-induced fluorescence (LIF) techniques. H atoms were produced by pulsed ultraviolet laser trace photolysis of O3, followed by reaction of O((1)D) with added H2. A second, delayed, frequency-mixed dye laser measured the reaction decay rate with the remaining ozone using LIF. We monitored either the H atom decay by two photon excitation at 205 nm and detection of red fluorescence, or the OH (v = 9) product time evolution with excitation of the B(2)Σ(+)-X(2)Π (0,9) band at 237 nm and emission in the blue B(2)Σ(+)-A(2)Σ(+) (0,7) band. By cooling the enclosed low pressure flow cell we obtained measurements from 140 to 305 K at 20 to 200 Torr in Ar. Small kinetic modeling corrections were made for secondary regeneration of H atoms. The results are consistent with the current NASA JPL recommendation for this rate constant and establish its extrapolation down to the lower temperatures of the mesosphere. PMID:27193050

  20. Strong mesospheric signal observed by the NICT Rayleigh lidar at Poker Flat after rocket launches

    NASA Astrophysics Data System (ADS)

    Sakanoi, K.; Murayama, Y.; Collins, R. L.; Mizutani, K.

    A Rayleigh lidar is operated at Poker Flat Research Range (65.1N, 147.5W, 394m ASL) as one of the nine instruments of the Alaska Project which is conducted by NICT (National institute of Information and Communications Technology; the former CRL) and the Geophysical Institute, the University of Alaska, Fairbanks. A Rayleigh lidar is usually used to measure density and temperature of the middle atmosphere, but in this presentation we focus on strong mesospheric signals observed by the NICT Rayleigh lidar when sounding rockets were launched at Poker Flat. The signals were possibly affected by rocket exhaust trail, but were detected about 15 min after rocket launches Those signals occurred with a small vertical interval of a few km, and the layers tended to become broader with time. For three different signals, the altitude, thickness, and duration are different. Those data suggest existence of some thin layered structure in the mesosphere to diffuse or transport rocket smoke, since if prevailing winds transport the smoke then it is not likely to form a layer. We will show basic characteristics of the signals in lidar data and background condition in the mesosphere and will discuss possible candidates which would diffuse or transport rocket smoke.

  1. Stratospheric and mesospheric HO2 observations from the Aura Microwave Limb Sounder

    NASA Astrophysics Data System (ADS)

    Millán, L.; Wang, S.; Livesey, N.; Kinnison, D.; Sagawa, H.; Kasai, Y.

    2015-03-01

    This study introduces stratospheric and mesospheric hydroperoxyl radical (HO2) estimates from the Aura Microwave Limb Sounder (MLS) using an offline retrieval (i.e. run separately from the standard MLS algorithm). This new data set provides two daily zonal averages, one during daytime from 10 to 0.0032 hPa (using day-minus-night differences between 10 and 1 hPa to ameliorate systematic biases) and one during nighttime from 1 to 0.0032 hPa. The vertical resolution of this new data set varies from about 4 km at 10 hPa to around 14 km at 0.0032 hPa. A description of the methodology and an error analysis are presented. Comparisons against the Whole Atmosphere Community Climate Model (WACCM), the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) and the Far Infrared Spectrometer (FIRS-2) measurements, as well as photochemical simulations, demonstrate the robustness of the retrieval and indicate that the retrieval is sensitive enough to detect mesospheric HO2 layers during both day and night. This new data set is the first long-term HO2 stratospheric and mesospheric satellite record and it provides needed constraints to help resolve the O3 deficit problem and the "HOx dilemma".

  2. Stratospheric and mesospheric HO2 observations from the Aura Microwave Limb Sounder

    NASA Astrophysics Data System (ADS)

    Millán, L.; Wang, S.; Livesey, N.; Kinnison, D.; Sagawa, H.; Kasai, Y.

    2014-09-01

    This study introduces stratospheric and mesospheric hydroperoxyl radical (HO2) estimates from the Aura Microwave Limb Sounder (MLS) using an offline retrieval (i.e. run separately from the standard MLS algorithm). This new dataset provides two daily zonal averages, one during daytime and one during nighttime, with a varying vertical resolution from about 4 km at 10 hPa to around 14 km at 0.0032 hPa. A description of the methodology and an error analysis are presented. Comparisons against the Whole Atmosphere Community Climate Model (WACCM), the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) and the Far Infrared Spectrometer (FIRS-2) measurements, as well as, photochemical simulations demonstrate the robustness of the retrieval and indicate that the retrieval is sensitive enough to detect mesospheric HO2 layers during both day and night. This new dataset is the first long-term HO2 stratospheric and mesospheric satellite record and it provides needed constraints to help resolve the O3 deficit problem and the "HOx dilemma".

  3. Solar activity influence on climatic variations of stratosphere and mesosphere in mid-latitudes

    NASA Technical Reports Server (NTRS)

    Taubenheim, J.; Entzian, G.; Voncossart, G.

    1989-01-01

    The direct modulation of temperature of the mid-latitude mesosphere by the solar-cycle EUV variation, which leads to greater heat input at higher solar activity, is well established. Middle atmosphere temperature modulation by the solar cycle is independently confirmed by the variation of reflection heights of low frequency radio waves in the lower ionosphere, which are regularly monitored over about 30 years. As explained elsewhere in detail, these reflection heights depend on the geometric altitude of a certain isobaric surface (near 80 k), and on the solar ionizing Lyman-alpha radiation flux. Knowing the solar cycle variation of Lyman-alpha how much the measured reflection heights would be lowered with the transition from solar minimum to maximum can be calculated, if the vertical baric structure of the neutral atmosphere would remain unchanged. An discrepancy between expected and observed height change must be explained by an uplifting of the isobaric level from solar minimum to maximum, caused by the temperature rise in the mesosphere. By integrating the solar cycle temperature changes over the height region of the middle atmosphere, and assuming that the lower boundary (tropopause) has no solar cycle variation, the magnitude of this uplifting can be estimated. It is given for the Lidar-derived and for the rocket-measured temperature variations. Comparison suggests that the real amplitude of the solar cycle temperature variation in the mesosphere is underestimated when using the rocket data, but probably overestimated with the Lidar data.

  4. Mesospheric vertical thermal structure and winds on Venus from HHSMT CO spectral-line observations

    NASA Astrophysics Data System (ADS)

    Rengel, Miriam; Hartogh, Paul; Jarchow, Christopher

    2008-08-01

    We report vertical thermal structure and wind velocities in the Venusian mesosphere retrieved from carbon monoxide ( 12CO J=2-1 and 13CO J=2-1) spectral line observations obtained with the Heinrich Hertz Submillimeter Telescope (HHSMT). We observed the mesosphere of Venus from two days after the second Messenger flyby of Venus (on 5 June 2007 at 23:10 UTC) during five days. Day-to-day and day-to-night temperature variations and short-term fluctuations of the mesospheric zonal flow were evident in our data. The extensive layer of warm air detected recently by SPICAV at 90-100 km altitude is also detected in the temperature profiles reported here. These data were part of a coordinated ground-based Venus observational campaign in support of the ESA Venus Express mission. Furthermore, this study attempts to cross-calibrate space- and ground-based observations, to constrain radiative transfer and retrieval algorithms for planetary atmospheres, and to contribute to a more thorough understanding of the global patterns of circulation of the Venusian atmosphere.

  5. A Multi-Instrument Measurement of a Mesospheric Bore at the Equator

    NASA Technical Reports Server (NTRS)

    Shiokawa, K.; Suzuki, S.; Otsuka, Y.; Ogawa, T.; Nakamura, T.; Mlynczak, M. G.; Russell, J. M., III

    2005-01-01

    We have made a comprehensive measurement of mesospheric bore phenomenon at the equator at Kototabang, Indonesia (0.2 deg S, 100.3 deg E), using an airglow imager, an airglow temperature photometer, a meteor radar, and the SABER instrument on board the TIMED satellite. The bore was detected in airglow images of both OH-band (peak emission altitude: 87 km) and 557.7-nm (96 km) emissions, as east-west front-like structure propagating northward with a velocity of 52-58 m/s. Wave trains with a horizontal wavelength of 30-70 km are observed behind the bore front. The airglow intensity decreases for all the mesospheric emissions of OI (557.7 nm), OH-band, O2-band (altitude: 94 km), and Na (589.3 nm) (90 km) after the bore passage. The rotational temperatures of both OH-band and O2-band also decrease approximately 10 K after the bore passage. An intense shear in northward wind velocity of 80m/s was observed at altitudes of 84-90 km by the meteor radar. Kinetic temperature profile at altitudes of 20-120 km was observed near Kototabang by TIMED/SABER. On the basis of these observations, we discuss generation and ducting of the observed mesospheric bore.

  6. Retrieval of sodium number density profiles in the mesosphere and lower thermosphere from SCIAMACHY limb emission measurements

    NASA Astrophysics Data System (ADS)

    Langowski, M. P.; von Savigny, C.; Burrows, J. P.; Rozanov, V. V.; Dunker, T.; Hoppe, U.-P.; Sinnhuber, M.; Aikin, A. C.

    2016-01-01

    An algorithm has been developed for the retrieval of sodium atom (Na) number density on a latitude and altitude grid from SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) limb measurements of the Na resonance fluorescence. The results are obtained between 50 and 150 km altitude and the resulting global seasonal variations of Na are analyzed. The retrieval approach is adapted from that used for the retrieval of magnesium atom (Mg) and magnesium ion (Mg+) number density profiles recently reported by Langowski et al. (2014). Monthly mean values of Na are presented as a function of altitude and latitude. This data set was retrieved from the 4 years of spectroscopic limb data of the SCIAMACHY mesosphere and lower thermosphere (MLT) measurement mode (mid-2008 to early 2012). The Na layer has a nearly constant peak altitude of 90-93 km for all latitudes and seasons, and has a full width at half maximum of 5-15 km. Small but significant seasonal variations in Na are identified for latitudes less than 40°, where the maximum Na number densities are 3000-4000 atoms cm-3. At middle to high latitudes a clear seasonal variation with a winter maximum of up to 6000 atoms cm-3 is observed. The high latitudes, which are only measured in the summer hemisphere, have lower number densities, with peak densities being approximately 1000 Na atoms cm-3. The full width at half maximum of the peak varies strongly at high latitudes and is 5 km near the polar summer mesopause, while it exceeds 10 km at lower latitudes. In summer the Na atom concentration at high latitudes and at altitudes below 88 km is significantly smaller than that at middle latitudes. The results are compared with other observations and models and there is overall a good agreement with these.

  7. Is chemical heating a major cause of the mesosphere inversion layer?

    NASA Astrophysics Data System (ADS)

    Meriwether, John W.; Mlynczak, Martin G.

    1995-01-01

    A region of thermal enhancement of the mesosphere has been detected on numerous occasions by in situ measurements, remote sensing from space, and lidar techniques. The source of these "temperature inversion layers" has been attributed in the literature to the dissipation relating to dynamical forcing by gravity wave or tidal activity. However, the conclusion that the dynamics of the mesopause region is the principal source for such anomalies is open to question. While it is certain that the dynamics of gravity wave breaking plays an important role in providing the source of momentum flux required to drive the diabatic circulation, evidence that gravity wave breaking can produce the inversion layer with amplitude as large as that observed in lidar measurements has been limited to results of numerical modeling. We note that an alternative source exists for the production of the thermal inversion layer in the mesosphere, i.e., the direct deposition of heat by exothermic chemical reactions. Two-dimensional modeling combining a comprehensive model of the mesosphere photochemistry with the dynamical transport of long-lived species shows that the region from 80 to 95 km may be heated as much as 3 to 10 K/d during the night and half this rate during the day. Given the uncertainties in our understanding of the dynamics and chemistry for the mesopause region, separating the two sources by passive observations of the mesosphere thermal structure looks to be difficult. Therefore we have considered an active means for producing a mesopause thermal layer, namely the release of ozone into the upper mesosphere from a rocket payload. The induced effects would include artificial enhancements of the OH and Na airglow intensities as well as the mesopause thermal structure. The advantage of the rocket release of ozone is that detection of these effects by ground-based imaging, radar, and lidar systems and comparison of these effects with model predictions would help quantify the

  8. Strato-mesospheric ClO observations by SMILES: error analysis and diurnal variation

    NASA Astrophysics Data System (ADS)

    Sato, T. O.; Sagawa, H.; Kreyling, D.; Manabe, T.; Ochiai, S.; Kikuchi, K.; Baron, P.; Mendrok, J.; Urban, J.; Murtagh, D.; Yasui, M.; Kasai, Y.

    2012-07-01

    Chlorine monoxide (ClO) is the key species for anthropogenic ozone loss in the middle atmosphere. We observed the ClO diurnal variation using the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on the International Space Station which has a non sun-synchronous orbit. This is the first global observation of the ClO diurnal variation from the stratosphere up to the mesosphere. The SMILES observation reproduced the diurnal variation of stratospheric ClO, an enhancement during a daytime, as observed by the Microwave Limb Sounder on the Upper Atmosphere Research Satellite (UARS/MLS). Mesospheric ClO has shown a different diurnal behavior with an enhancement during nighttime. The ClO enhancement was found at a pressure of 0.02 hPa (about 70 km) with an amplitude of about 100 pptv and reached up to 0.01 hPa (80 km) in the zonal mean of 50° N-65° N in January-February 2010. The observation of mesospheric ClO was possible due to the 10-20 times better signal-to-noise ratio of the spectra than those of past microwave/submillimeter-wave limb-emission sounders. We performed a quantitative error analysis for the strato- and mesospheric ClO of the Level-2 research (L2r) product version 2.1.5 taking into account all possible error contributions; i.e. errors due to spectrum noise, smoothing and uncertainties in the radiative transfer model and instrument function. The SMILES L2r v2.1.5 ClO data are useful over the range 0.01 and 100 hPa with a total error of 10-30 pptv (about 10%) with averaging of 100 profiles. The vertical resolution is 3-5 km and 5-8 km for the stratosphere and mesosphere, respectively. The performance of the SMILES observation opens the new opportunity to investigate ClO up to the mesopause.

  9. Strato-mesospheric ClO observations by SMILES: error analysis and diurnal variation

    NASA Astrophysics Data System (ADS)

    Sato, T. O.; Sagawa, H.; Kreyling, D.; Manabe, T.; Ochiai, S.; Kikuchi, K.; Baron, P.; Mendrok, J.; Urban, J.; Murtagh, D.; Yasui, M.; Kasai, Y.

    2012-11-01

    Chlorine monoxide (ClO) is the key species for anthropogenic ozone losses in the middle atmosphere. We observed ClO diurnal variations using the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on the International Space Station, which has a non-sun-synchronous orbit. This includes the first global observations of the ClO diurnal variation from the stratosphere up to the mesosphere. The observation of mesospheric ClO was possible due to 10-20 times better signal-to-noise (S/N) ratio of the spectra than those of past or ongoing microwave/submillimeter-wave limb-emission sounders. We performed a quantitative error analysis for the strato- and mesospheric ClO from the Level-2 research (L2r) product version 2.1.5 taking into account all possible contributions of errors, i.e. errors due to spectrum noise, smoothing, and uncertainties in radiative transfer model and instrument functions. The SMILES L2r v2.1.5 ClO data are useful over the range from 0.01 and 100 hPa with a total error estimate of 10-30 pptv (about 10%) with averaging 100 profiles. The SMILES ClO vertical resolution is 3-5 km and 5-8 km for the stratosphere and mesosphere, respectively. The SMILES observations reproduced the diurnal variation of stratospheric ClO, with peak values at midday, observed previously by the Microwave Limb Sounder on the Upper Atmosphere Research Satellite (UARS/MLS). Mesospheric ClO demonstrated an opposite diurnal behavior, with nighttime values being larger than daytime values. A ClO enhancement of about 100 pptv was observed at 0.02 to 0.01 hPa (about 70-80 km) for 50° N-65° N from January-February 2010. The performance of SMILES ClO observations opens up new opportunities to investigate ClO up to the mesopause.

  10. Polar stratospheric cloud measurements by means of depolarization lidar in the Antarctic

    NASA Astrophysics Data System (ADS)

    Stefanutti, L.

    1991-02-01

    POLE (Polar Ozone Lidar Experiment) is a cooperative project between the French and Italian services. It was started with the implementation of a first depolarization backscattering lidar for measurements both of background stratospheric aerosols and Polar Stratospheric Clouds (PSCs). A complex Ozone lidar was also installed which will replace the backscattering system and extend its measurements to tropospheric and stratospheric Ozone and to stratospheric and mesospheric temperatures. This new system allows also the measurement of the backscattered and depolarized signal produced by PSCs and background aerosols. The depolarization technique seemed to be quite efficient in the detection of different types of PSCs.

  11. Polar stratospheric cloud measurements by means of depolarization lidar in the Antarctic

    NASA Technical Reports Server (NTRS)

    Stefanutti, L.

    1991-01-01

    POLE (Polar Ozone Lidar Experiment) is a cooperative project between the French and Italian services. It was started with the implementation of a first depolarization backscattering lidar for measurements both of background stratospheric aerosols and Polar Stratospheric Clouds (PSCs). A complex Ozone lidar was also installed which will replace the backscattering system and extend its measurements to tropospheric and stratospheric Ozone and to stratospheric and mesospheric temperatures. This new system allows also the measurement of the backscattered and depolarized signal produced by PSCs and background aerosols. The depolarization technique seemed to be quite efficient in the detection of different types of PSCs.

  12. Detection of meteoric smoke particles in the mesosphere by a rocket-borne mass spectrometer

    NASA Astrophysics Data System (ADS)

    Robertson, Scott; Dickson, Shannon; Horányi, Mihaly; Sternovsky, Zoltan; Friedrich, Martin; Janches, Diego; Megner, Linda; Williams, Bifford

    2014-10-01

    In October 2011, two CHAMPS (Charge And Mass of meteoric smoke ParticleS) sounding rockets were launched into the polar mesosphere, each carrying an electrostatic multichannel mass analyzer for charged meteoric smoke particles (MSPs) that operated from 60 to 100 km and returned data on the number density of the charged MSPs in several ranges of mass. The payloads also carried Faraday rotation antennas and an array of plasma probes for determining electron and ion densities and the payload charging potential, thus providing a comprehensive picture of the distribution of charges over a wide range of altitudes that can be compared with models for the vertical distribution of MSPs and for the distribution of charge. The launches were from the Andøya Rocket Range, Norway, following the end of the noctilucent cloud season to avoid detection of ice. A night launch (11 October 21:50 UT) and a day launch (13 October 13:50 UT) helped to elucidate the role of solar ultraviolet in determining the charge state of the particles. The night data show a distinct change in the charge state of MSPs at the D-region ledge (~78 km) below which the density of free electrons is greatly reduced. Above the ledge, negative MSPs are detected at up to 92 km, have number densities reaching ~200 cm-3, and positive MSPs are absent. Below the ledge, positive and negative MSPs are about equally abundant, each with densities of ~2000 cm-3 at 70 km and with slightly lower densities at 60 km. The MSPs are seen predominantly in mass bins spanning 500-2000 amu and 2000-8000 amu, with more massive particles (radii above ~1.2 nm assuming a smoke particle density of 2 g/cm3) having number densities below the detection threshold (10 cm-3) and less massive particles being indistinguishable from ions. The daytime launch data show positive MSPs present only below the ledge and their number density is reduced to below 300 cm-3. The daytime data show negative MSPs both above and below the D-region ledge and

  13. Comparisons of Na densities, Fe densities, and temperature measured over south polar cap with model predictions

    NASA Astrophysics Data System (ADS)

    Chu, X.; Gardner, C. S.; Vondrak, T.; Murray, B.; Plane, J. M.; Roble, R. G.; Espy, P. J.; Kawahara, T.

    Mesospheric Na and Fe layer densities and temperatures were measured by lidar systems at the South Pole, Syowa (69S, 39E), and Rothera (67.5S, 68.0W) during the past several years. Comparison of the wintertime temperatures measured above these sites with TIME-GCM predictions, suggests that the model over-estimates the compressional heating associated with downwelling. When simulating the winter Na and Fe densities at the pole using the UEA 1-D chemistry models, a 2-D general circulation model SOCRATES was used to predict the meridional and downward vertical transportation of O, H, etc. from the sunlit lower latitude into the polar vortex. However, the simulation indicates that the circulation, especially downward transport into the polar vortex, is overestimated by the general circulation model. Thus, the wintertime Na layer nearly disappears in the chemistry model, which does not agree with the maximum Na abundance observed in winter. In summer, the model correctly predicts the observed depletion of the metal atoms below 90 km. This results from the uptake of the metals onto ice particles, which seem to be a persistent feature of the summertime upper mesosphere at high latitudes. This paper will show that the observed seasonal behavior of the metal layers provides a rigorous test of general circulation models in the upper mesosphere.

  14. Polarization developments

    SciTech Connect

    Prescott, C.Y.

    1993-07-01

    Recent developments in laser-driven photoemission sources of polarized electrons have made prospects for highly polarized electron beams in a future linear collider very promising. This talk discusses the experiences with the SLC polarized electron source, the recent progress with research into gallium arsenide and strained gallium arsenide as a photocathode material, and the suitability of these cathode materials for a future linear collider based on the parameters of the several linear collider designs that exist.

  15. Neuronal polarization.

    PubMed

    Takano, Tetsuya; Xu, Chundi; Funahashi, Yasuhiro; Namba, Takashi; Kaibuchi, Kozo

    2015-06-15

    Neurons are highly polarized cells with structurally and functionally distinct processes called axons and dendrites. This polarization underlies the directional flow of information in the central nervous system, so the establishment and maintenance of neuronal polarization is crucial for correct development and function. Great progress in our understanding of how neurons establish their polarity has been made through the use of cultured hippocampal neurons, while recent technological advances have enabled in vivo analysis of axon specification and elongation. This short review and accompanying poster highlight recent advances in this fascinating field, with an emphasis on the signaling mechanisms underlying axon and dendrite specification in vitro and in vivo.

  16. Polar Bear

    USGS Publications Warehouse

    Amstrup, S.D.; ,; Lentfer, J.W.

    1988-01-01

    Polar bears are long-lived, late-maturing carnivores that have relatively low rates of reproduction and natural mortality. Their populations are susceptible to disturbance from human activities, such as the exploration and development of mineral resources or hunting. Polar bear populations have been an important renewable resource available to coastal communities throughout the Arctic for thousands of years.

  17. Polarized rainbow.

    PubMed

    Können, G P; de Boer, J H

    1979-06-15

    The Airy theory of the rainbow is extended to polarized light. For both polarization directions a simple analytic expression is obtained for the intensity distribution as a function of the scattering angle in terms of the Airy function and its derivative. This approach is valid at least down to droplet diameters of 0.3 mm in visible light. The degree of polarization of the rainbow is less than expected from geometrical optics; it increases with droplet size. For a droplet diameter >1 mm the locations of the supernumerary rainbows are equal for both polarization directions, but for a diameter <1 mm the supernumerary rainbows of the weaker polarization component are located between those in the strong component. PMID:20212586

  18. Resolving the mesospheric nighttime 4.3 µm emission puzzle: Laboratory demonstration of new mechanism for OH(υ) relaxation

    NASA Astrophysics Data System (ADS)

    Kalogerakis, Konstantinos S.; Matsiev, Daniel; Sharma, Ramesh D.; Wintersteiner, Peter P.

    2016-09-01

    We report laboratory results that support a recently proposed mechanism for relaxation of highly vibrationally excited hydroxyl radical by ground-state oxygen atoms (Sharma et al., GRL 42, 4639-4647 (2015)). According to this mechanism, which eventually leads to an enhancement of nocturnal 4.3 µm CO2 emissions in the mesosphere, the deactivation of OH(high υ) by O(3P) involves a fast, spin-allowed, multiquantum vibration-to-electronic (V-E) energy transfer process generating O(1D). We present laser-based experiments that demonstrate these energy transfer processes in action and discuss some implications of the new mechanism for mesospheric OH. These developments represent a breakthrough addressing the long-standing problem of unacceptably large discrepancies between models and observations of the nocturnal mesospheric 4.3 µm emission.

  19. Response of the mesosphere to human-induced perturbations and solar variability calculated by a 2-D model

    NASA Astrophysics Data System (ADS)

    Khosravi, Rashid; Brasseur, Guy; Smith, Anne; Rusch, David; Walters, Stacy; Chabrillat, Simon; Kockarts, Gaston

    2002-09-01

    We have used the improved NCAR interactive 2-D model (SOCRATES) to investigate the chemical and thermal response of the mesosphere to composition changes from the preindustrial era (˜1850) to the present, to doubling the CO2 concentration, and to the 11-year solar flux variability. The calculations show that all regions in the model mesosphere have cooled relative to the preindustrial times. The mesopause region has cooled by ˜5 K and the winter pole by up to 9 K near 60 km. Ozone mixing ratio has decreased by about 5% in the lower mesosphere and by about 30% near the summer mesopause region (caused by a dramatic increase in [OH]). Doubling the CO2 abundance cools the whole mesosphere by about 4-16 K and has a complicated effect on O3, which exhibits an alternating increase/decrease behavior from the lower mesosphere up to the mesopause region. Similar results are obtained, in both magnitude and structure, for the O3 response to a decrease in solar UV flux. Similarities are also found in the response of T, OH, and H to these two perturbations. These results lead to the conclusion that the long-term increase in the well-mixed greenhouse gases, in particular CO2, alters the thermal structure and chemical composition of the mesosphere significantly and that these anthropogenic effects are of the same magnitude as the effects associated with the 11-year solar cycle. Thus, the difference in the timescales involved suggests that the anthropogenic signal over periods of typically 10 years is smaller than the signal generated by the 11-year solar variability. Finally, analysis of the results from a simulation of the combined perturbations (2 × CO2 + 11-year solar variability) shows that, for the most part, the solar variability does not interact with increasing CO2 and vice versa; that is, the two effects are additive.

  20. Measurements of mesospheric water vapour, aerosols and temperatures with the Spectral Absorption Line Imager (SALI-AT)

    NASA Astrophysics Data System (ADS)

    Shepherd, M. G.; Mullins, M.; Brown, S.; Sargoytchev, S. I.

    2001-08-01

    Water vapour concentration is one of the most important, yet one of the least known quantities of the mesosphere. Knowledge of water vapour concentration is the key to understanding many mesospheric processes, including the one that is primary focus of our investigation, mesospheric clouds (MC). The processes of formation and occurrence parameters of MC constitute an interesting problem in their own right, but recently evidence has been provided which suggests that they are a critical indicator of atmospheric change. The aim of the SALI-AT experiment is to make simultaneous (although not strictly collocated) measurements of water vapour, aerosols and temperature in the mesosphere and the mesopause region under twilight condition in the presence of mesospheric clouds. The water vapour will be measured in the regime of solar occultation utilizing a water vapour absorption band at 936 nm wavelength employing the SALI (Spectral Absorption Line Imager) instrument concept. A three-channel zenith photometer, AT-3, with wavelengths of 385 nm, 525 nm, and 1040 nm will measure Mie and Rayleigh scattering giving both mesospheric temperature profiles and the particle size distribution. Both instruments are small, low cost and low mass. It is envisioned that the SALI-AT experiment be flown on a small rocket - the Improved Orion/Hotel payload configuration, from the Andoya Rocket range, Norway. Alternatively the instrument can be flown as a "passenger" on larger rocket carrying other experiments. In either case flight costs are relatively low. Some performance simulations are presented showing that the instrument we have designed will be sufficiently sensitive to measure water vapor in concentrations that are expected at the summer mesopause, about 85 km height.

  1. Causative Mechanisms of Tropical (10°N-15°N) Mesospheric Inversion Layers

    NASA Astrophysics Data System (ADS)

    Ramesh, Karanam; Sundararajan, Sridharan; Vijaya Bhaskara Rao, S.

    2016-07-01

    The inversion of temperature gradient from negative to positive superimposed upon the characteristically decreasing mesospheric thermal structure is known as Mesospheric Inversion Layer (MIL). Gravity wave breaking, planetary wave critical level interaction and the chemical heating have been suggested as potential causative mechanisms for the occurrence of the MILs. Although the morphological characteristics of MIL have been studied in detail at different sites using various instrumental techniques, their causative mechanisms are still unknown. In the present study, nearly all these major causative mechanisms have been addressed through a few case studies observed from Rayleigh lidar and TIMED-SABER (Thermosphere Ionosphere Mesosphere Energetics and Dynamics - Sounding of Atmosphere by Broadband Emission Radiometry) nightly temperatures over a tropical site, Gadanki (13.5°N,79.2°E). A few large MILs are observed above ˜80 km with amplitude and thickness of ˜50 K and ˜5 km respectively in 2007 and 2011 which are found to be predominantly due to gravity wave breaking and large chemical heating rate (˜15 K/day) by the exothermic reaction, H+O _{3}->OH+O _{2} respectively. It is also found that the SABER shows larger ozone (O _{3}) mixing ratios at the inversion heights (˜80-85 km) during the MIL events in 2011. In another special case study, a triple layered MIL event with three inversion layers at ˜70 km (˜11 K), 80 km (˜44 K), 90 km (˜109 K) has been observed in September 2011 over Gadanki region. It is found that these three inversion layers are respectively due to planetary wave breaking, gravity wave tidal interaction and chemical heating by the reaction, O+O+M->O _{2}+M.

  2. Short-Period Mesospheric Gravity Waves and Diurnal Tidal Interactions at a Critical Layer

    NASA Astrophysics Data System (ADS)

    Ejiri, M. K.; Taylor, M. J.; Franke, S. J.

    2007-05-01

    The US Maui-MALT program is designed to investigate the properties and dynamics of the low-latitude mesosphere and lower thermosphere region (MLT) in exceptional detail. On June 29, 2003, the University of Illinois Meteor Wind Radar (MWR) at Kihei, Maui (20.8°N, 156.4°W) observed a diurnal tidal wave with an amplitude twice as large as normal at mesospheric height (80--100 km) for 7 hours (1400--2100 UT). At the same time, the Utah State University Mesospheric Temperature Mapper (MTM) measured OH and O2 band emission intensities and temperatures at nearby Haleakala Crater, Maui (20.8°N, 156.2°W). The MTM observed a short-period gravity wave (GW) event propagating through this region for most of the night from 600 to 1500 UT. The GWs disappeared from the O2 band data (peak altitude: ~94 km) and the OH band data (~87 km) around 1400 UT and 1430 UT, respectively. Qualitative and quantitative investigations of relationship between the observed GW dissipations and the increasing background wind field show the following. 1. The wave dissipation observed in both emissions was caused by wave absorption at a critical layer (CL) when the background wind speed exceeded the wave phase speed. 2. The wave absorption at the CL appears to accelerate the background wind. 3. The acceleration occurred over a wide altitude range (80--100 km) because the CL was moving down in association with downward progression of the diurnal tidal wave. 4. The change in background wind speed caused by the GW absorption at the CL was comparable with the induced tidal effect.

  3. Model Studies of Electrical Coupling Processes in Equatorial Mesosphere and Lower Ionosphere

    NASA Astrophysics Data System (ADS)

    Tonev, Peter; Velinov, Peter

    2016-07-01

    The quasi-electrostatic response of equatorial lower ionosphere and mesosphere to forcing from below by electrical sources located in the troposphere (e.g. thunderclouds) or at surface (e.g. related to earthquakes) is studied. Such sources generate quasi-static (QS) electric fields in the lower ionosphere and mesosphere which can be large enough in nighttime conditions to cause electron heating, modifications of conductivity and electron density, etc. We demonstrate that this response to the forcing from below highly depends on the geomagnetic latitude determining the magnetic field lines inclination, and thus, the tensor of anisotropic conductivity. Our previous results show that the QS electric fields in the lower nighttime ionosphere above tropospheric sources are much bigger and have larger horizontal extension than those generated at high latitudes by otherwise same conditions. Now we estimate by modeling the electric currents and fields generated at equatorial latitudes in lower ionosphere and mesosphere above electrical charges located in the troposphere or at ground which can have different horizontal dimensions during quiet periods and of their self-consistent effects to electron heating and conductivity. Specific configurations of electric currents and distributions of related electric fields are estimated first by constant (ambient) conductivity. Then, these are evaluated self-consistently with conductivity modification. The electric currents are re-oriented above ~85 km and flow in a narrow horizontal layer where they dense. Respectively, the electric fields and their effect on conductivity have much larger horizontal scale than at middle latitudes (few hundred of kilometers). Sources of large horizontal dimensions, such as mesoscale convective structures and complexes or earthquakes, cause enhancements of electric fields and their effects due to superposition of horizontally reoriented electric currents well above 70 km. In case of thunderstorms these

  4. Thermal structure and minor species distribution of Venus mesosphere by ALMA submm observations

    NASA Astrophysics Data System (ADS)

    Piccialli, Arianna; Moreno, Raphael; Encrenaz, Therese; Fouchet, Thierry; Lellouch, Emmanuel; Moullet, Arielle; Widemann, Thomas

    2015-11-01

    Venus upper atmosphere (70-150 km altitude) is a transition region characterized by a complex dynamics: strong retrograde zonal winds dominate the lower mesosphere while a solar-to-antisolar circulation is observed in the upper mesosphere/lower thermosphere. In addition, photochemical processes play an important role at these altitudes and affect the thermal structure and chemical stability of the entire atmosphere. Sulfur dioxide and water vapor are key species in the photochemical cycles taking place in the troposphere and mesosphere of Venus. They are carried by convective transport, together with the Hadley circulation, up to about 60 km where SO2 is photodissociated and oxydated, leading to the formation of H2SO4 which condenses in the clouds enshrouding the planet. Previous observations obtained by several instruments on board Venus Express and during ground-based campaigns have shown evidence of strong temporal variations, both on day-to-day as well as longer timescales, of density, temperature and SO2 abundance. Such strong variability is still not well understood.Submillimeter observations obtained with the Atacama Large Millimeter Array (ALMA) offer the possibility of probing Venus upper mesosphere and of monitoring minor species, winds and the thermal structure. A first set of observations was obtained on November 14, 15, 26 and 27, 2011 during the first ALMA Early Science observation cycle. These observations targeted SO2, SO, HDO and CO transitions around 345 GHz during four sequences of 30 minutes each. The Venus’ disk was about 11” with an illumination factor of 90%, so that mostly the dayside of the planet was mapped.Assuming nominal night-time and dayside CO abundance profiles from Clancy et al. 2013, we retrieved vertical temperature profiles over the entire disk as a function of latitude and local time for the four days of observation. Temperature profiles were later used to derive the abundances of minor species (HDO, SO, SO2) in each pixel

  5. Influence of sprite streamers in the mesospheric chemical and thermal balance

    NASA Astrophysics Data System (ADS)

    Parra-Rojas, Francisco C.; Luque, Alejandro; Gordillo-Vázquez, Francisco J.

    2015-04-01

    We present new results to contribute to the fundamental understanding of the chemistry of non-equilibrium plasmas produced by nighttime sprite streamers in the mesosphere and their influence on the chemical composition and thermal evolution of the upper atmosphere. This contribution describes the kinetic model used and the time evolution of the concentration of many important species for the sprite and its afterglow through an upgrade of previous TLE kinetic models [1], [2]. A one-dimensional self-consistent model has been developed to study the chemical and thermal effects of a single sprite streamer in the Earth mesosphere. We have used sprite streamer profiles with three different driving current durations (5 ms, 50 ms and 100 ms) between 50 and 80 km of altitude and considering a kinetic scheme of air with 20 chemical species. Our model predicts strong increases in practically all the concentrations of the species studied at the moment of the streamer head passage. Moreover, their densities remain high during the streamer afterglow phase. The electron concentration can reach values of up to 108 cm-3 in the three cases analyzed. The model also predicts an important enhancement, of several orders of magnitude above ambient values, of nitrogen oxides (NOx and N2O) and the considered metastables species (N2(A), O2(a), O2(b)). Metastables are capable of storing energy for relatively long time (hundreds of seconds). On the other hand, we found that the 4.26 μm IR emission brightness of CO2 can exceed in 4 orders of magnitude the threshold of visibility (1 MR) at low altitudes (< 65 km) for the cases of intermediate (50 ms) and long (100 ms) driving currents. These results suggest the possibility of detecting sprite IR emissions from space with the appropriate instrumentation. Moreover, according to our model, the Meinel emission brightness of N2+ could also reach the threshold of visibility below 50 km. Finally, we found that the thermal impact of sprites in the

  6. SABER (TIMED) and MLS (UARS) Temperature Observations of Mesospheric and Stratospheric QBO and Related Tidal Variations

    NASA Technical Reports Server (NTRS)

    Huang, Frank T.; Mayr, Hans G.; Reber, Carl A.; Russell, James; Mlynczak, Marty; Mengel, John

    2006-01-01

    More than three years of temperature observations from the SABER (TIMED) and MLS WARS) instruments are analyzed to study the annual and inter-annual variations extending from the stratosphere into the upper mesosphere. The SABER measurements provide data from a wide altitude range (15 to 95 km) for the years 2002 to 2004, while the MLS data were taken in the 16 to 55 km altitude range a decade earlier. Because of the sampling properties of SABER and MLS, the variations with local solar time must be accounted for when estimating the zonal mean variations. An algorithm is thus applied that delineates with Fourier analysis the year-long variations of the migrating tides and zonal mean component. The amplitude of the diurnal tide near the equator shows a strong semiannual periodicity with maxima near equinox, which vary from year to year to indicate the influence from the Quasi-biennial Oscillation (QBO) in the zonal circulation. The zonal mean QBO temperature variations are analyzed over a range of latitudes and altitudes, and the results are presented for latitudes from 48"s to 48"N. New results are obtained for the QBO, especially in the upper stratosphere and mesosphere, and at mid-latitudes. At Equatorial latitudes, the QBO amplitudes show local peaks, albeit small, that occur at different altitudes. From about 20 to 40 km, and within about 15" of the Equator, the amplitudes can approach 3S K for the stratospheric QBO or SQBO. For the mesospheric QBO or MQBO, we find peaks near 70 km, with temperature amplitudes reaching 3.5"K, and near 85 km, the amplitudes approach 2.5OK. Morphologically, the amplitude and phase variations derived from the SABER and MLS measurements are in qualitative agreement. The QBO amplitudes tend to peak at the Equator but then increase again pole-ward of about 15" to 20'. The phase progression with altitude varies more gradually at the Equator than at mid-latitudes. A comparison of the observations with results from the Numerical Spectral

  7. Observations of the 5-day wave in the mesosphere and lower thermosphere

    NASA Technical Reports Server (NTRS)

    Wu, D. L.; Hays, P. B.; Skinner, W. R.

    1994-01-01

    The 5-day planetary wave has been detected in the winds measured by the High Resolution Doppler Imager (HRDI) on the Upper Atmosphere Research Satellite (UARS) in the mesosphere and lower thermosphere (50-110 km). The appearances of the 5-day wave are transient, with a lifetime of 10-20 days in the two-year data set. The structures of selected 5-day wave events are in generally good agreement with the (1,1) Rossby normal mode for both zonal and meridional components. A climatology of the 5-day wave is presented for an altitude of 95 km and latitudes mainly between 40 deg S and 40 deg N.

  8. The mean observed meteorological structure and circulation of the stratosphere and mesosphere

    NASA Technical Reports Server (NTRS)

    Theon, J. S.; Smith, W. S.; Casey, J. F.; Kirkwood, B. R.

    1972-01-01

    Meteorological soundings of the upper stratosphere and mesosphere, conducted with in situ rocket techniques during all seasons of the year from several sites, ranging in latitude from 8 deg S to 71 deg N, are analyzed. The resulting data are compiled into mean monthly and seasonal profiles of temperature, pressure, density, and wind for each site and are presented in graphical and tabular form. Analyses of these mean values produced time cross sections, quasi-meridional cross sections, and constant level maps which are included.

  9. Measurements of the structure and circulation of the stratosphere and mesosphere, 1971-2

    NASA Technical Reports Server (NTRS)

    Smith, W. S.; Theon, J. S.; Wright, D. U., Jr.; Ramsdale, D. J.; Horvath, J. J.

    1974-01-01

    Complete data from a total of 43 meteorological rocket soundings of the stratosphere and mesosphere conducted from Barrow, Alaska; Churchill, Canada; Wallops Island Va.; and Kourou, French Guiana are presented. These data consist of temperature, pressure, density, and wind profiles from 35 acoustic grenade soundings that cover the 30 to 90 km altitude range, and temperature, pressure, and density profiles from 8 pitot probe soundings that cover the 25 to 120 km altitude range. Errors for each of the 35 acoustic grenade soundings are also included.

  10. Venus mesosphere and thermosphere. III. Three-dimensional general circulation with coupled dynamics and composition

    SciTech Connect

    Bougher, S.W.; Roble, R.G.E.; Dickinson, R.E.; Ridley, E.C.

    1988-03-01

    The three-dimensional structure and circulation of Venus' upper mesosphere and thermosphere is examined by means of a modification of NCAR's earth thermosphere general circulation model, using the parameterizations from an earlier two-dimensional Venus model that included eddy diffusion and wave drag. Many of the observed Venus thermosphere features are found to be reproduced by the model, which thereby serves as a benchmark on which to incorporate additional minor constituents and test new self-consistent parameterizations for wave drag and superrotation. 36 references.

  11. Observations of Mesospheric Turbulence by Rocket Probe and VHF Radar, Part 2.4A

    NASA Technical Reports Server (NTRS)

    Royrvik, O.; Smith, L. G.

    1984-01-01

    Data from the Jicamarca VHF radar and from a Languir probe fine-structure on a Nike Orion rocket launched from Punto Lobos, Peru, have been compared. A single mesospheric scattering layer was observed by the radar. The Langmuir probe detected irregularities in the electron-density profile in a narrow region between 85.2 and 86.6 km. It appears from a comparison between these two data sets that turbulence in the neutral atmosphere is the mechanism generating the refractive index irregularities.

  12. Inter-Hemispheric Coupling During Recent North Polar Summer Periods as Predicted by MaCWAVE/MIDAS Rocket Data and Traced by TIMED/SABER Measurements

    NASA Technical Reports Server (NTRS)

    Goldberg, Richard A.; Feofilov, Artem G.; Kutepov, Alexander A.; Pesnell, W. Dean; Schmidlin, Francis J.

    2011-01-01

    In July, 2002, the MaCWAVE-MIDAS Rocket Program was launched from And0ya Rocket Range (ARR) in Norway. Data from these flights demonstrated that the polar summer mesosphere during this period was unusual, at least above ARR. Theoretical studies have since been published that imply that the abnormal characteristics of this polar summer were generated by 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 and compare them with the features observed in the ensuing eight years. For background, the TIMED Satellite was launched on December 7, 2001 to study the dynamics and energy of the mesosphere and lower thermosphere. The SABER instrument is a limb scanning infrared radiometer designed to measure temperature of the region as well as a large number of minor constituents. In this study, we review the MaCWAVE rocket results. Next, we investigate 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). Weekly averages are used to make comparisons between the winter and summer hemispheres. Furthermore, the data analysis agrees with recent theoretical studies showing that this behavior is a result of anomalous dynamical events in the southern hemisphere. The findings discussed here clearly show the value of scientific rocket flights used in a discovery mode.

  13. Polarizing cues.

    PubMed

    Nicholson, Stephen P

    2012-01-01

    People categorize themselves and others, creating ingroup and outgroup distinctions. In American politics, parties constitute the in- and outgroups, and party leaders hold sway in articulating party positions. A party leader's endorsement of a policy can be persuasive, inducing co-partisans to take the same position. In contrast, a party leader's endorsement may polarize opinion, inducing out-party identifiers to take a contrary position. Using survey experiments from the 2008 presidential election, I examine whether in- and out-party candidate cues—John McCain and Barack Obama—affected partisan opinion. The results indicate that in-party leader cues do not persuade but that out-party leader cues polarize. This finding holds in an experiment featuring President Bush in which his endorsement did not persuade Republicans but it polarized Democrats. Lastly, I compare the effect of party leader cues to party label cues. The results suggest that politicians, not parties, function as polarizing cues. PMID:22400143

  14. Observations of the 10 micrometer natural laser emission from the mesospheres of Mars and Venus

    NASA Technical Reports Server (NTRS)

    Deming, D.; Espenak, F.; Jennings, D.; Kostiuk, T.; Mumma, M. J.

    1983-01-01

    Observations of the total flux and center to limb dependence of the nonthermal emission occurring in the cores of the 9.4 and 10.4 micrometers CO2 bands on Mars are compared to a theoretical model based on this mechanism. The model successfully reproduces the observed center to limb dependence of this emission, to within the limits imposed by the spatial resolution of the observations of Mars and Venus. The observed flux from Mars agrees closely with the prediction of the model; the flux observed from Venus is 74% of the flux predicted by the model. This emission is used to obtain the kinetic temperatures of the Martian and Venusian mesospheres. For Mars near 70 km altitude, a rotational temperature analysis using five lines gives T = 135 + or - 20 K. The frequency width of the emission is also analyzed to derive a temperature of 126 + or - 6 K. In the case of the Venusian mesosphere near 109 km, the frequency width of the emission gives T = 204 + or - 10 K.

  15. Chemical and thermal impacts of sprite streamers in the Earth's mesosphere

    NASA Astrophysics Data System (ADS)

    Parra-Rojas, F. C.; Luque, A.; Gordillo-Vázquez, F. J.

    2015-10-01

    A one-dimensional self-consistent model has been developed to study the chemical and thermal effects of a single sprite streamer in the Earth's mesosphere. We have used sprite streamer profiles with three different driving current durations (5 ms, 50 ms, and 100 ms) between 50 and 80 km of altitude and considering a kinetic scheme of air with more than 90 chemical species. Our model predicts strong increases in practically all the concentrations of the species studied at the moment of the streamer head passage. Moreover, their densities remain high during the streamer afterglow phase. The concentration of electrons can reach values of up to 108 cm-3 in the three cases analyzed. The model also predicts an important enhancement, of several orders of magnitude above ambient values, of nitrogen oxides and several metastables species. On the other hand, we found that the 4.26 μm IR emission brightness of CO2 can reach 10 GR at low altitudes (< 65 km) for the cases of intermediate (50 ms) and long (100 ms) driving currents. These results suggest the possibility of detecting sprite IR emissions from space with the appropriate instrumentation. Finally, we found that the thermal impact of sprites in the Earth's mesosphere is proportional to the driving current duration. This produces variations of more than 40 K (in the extreme case of a 100 ms driving current) at low altitudes (< 55 km) and at about 10 s after the streamer head.

  16. Mesospheric temperature estimation from meteor decay times during Geminids meteor shower

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    Meteor radar observations at the Sodankylä Geophysical Observatory (67° 22'N, 26° 38'E, Finland) indicate that the mesospheric temperature derived from meteor decay times is systematically underestimated by 20-50 K during the Geminids meteor shower which has peak on 13 December. A very good coincidence of the minimum of routinely calculated temperature and maximum of meteor flux (the number of meteors detected per day) was observed regularly on that day in December 2008-2014. These observations are for a specific height-lifetime distribution of the Geminids meteor trails and indicate a larger percentage of overdense trails compared to that for sporadic meteors. A consequence of this is that the routine estimates of mesospheric temperature during the Geminids are in fact underestimates. The observations do, however, indicate unusual properties (e.g., mass, speed, or chemical composition) of the Geminids meteoroids. Similar properties were found also for Quadrantids in January 2009-2015, which like the Geminids has as a parent body an asteroid, but not for other meteor showers.

  17. Mesospheric Non-Migrating Tides Generated With Planetary Waves: II Influence of Gravity Waves

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    We demonstrated that, in our model, non-linear interactions between planetary waves (PW) and migrating tides could generate in the upper mesosphere non-migrating tides with amplitudes comparable to those observed. The Numerical Spectral Model (NSM) we employ incorporates Hines Doppler Spread Parameterization for small-scale gravity waves (GW), which affect in numerous ways the dynamics of the mesosphere. The latitudinal (seasonal) reversals in the temperature and zonal circulation, which are largely caused by GWs (Lindzen, 198l), filter the PWs and contribute to the instabilities that generate the PWs. The PWs in turn are amplified by the momentum deposition of upward propagating GWs, as are the migrating tides. The GWs thus affect significantly the migrating tides and PWs, the building blocks of non-migrating tides. In the present paper, we demonstrate that GW filtering also contributes to the non-linear coupling between PWs and tides. Two computer experiments are presented to make this point. In one, we simply turn off the GW source to show the effect. In the second case, we demonstrate the effect by selectively suppressing the momentum source for the m = 0 non-migrating tides.

  18. Diurnal variations of mesospheric ozone obtained by ground-based microwave radiometry

    NASA Technical Reports Server (NTRS)

    Zommerfelds, W. C.; Kunzi, K. F.; Summers, M. E.; Bevilacqua, R. M.; Strobel, D. F.

    1989-01-01

    From December 1986 until April 1987 ground-based microwave observations of the diurnal variation of mesospheric ozone were made over Bern, Switzerland. These data were of sufficient quality to define the characteristics diurnal behavior of the ozone mixing ratio during winter and equinoctial conditions. The observed diurnal variation of ozone peaks at about 74 km, where its amplitude is about a factor of 6. At 65 km the observed diurnal variation is a factor of 3, whereas at 55 km it is only a factor of 1.4. One-dimensional model calculations accurately reproduce the relative diurnal variation of ozone at equinox, suggesting that the model value of the ozone photolysis rate coefficient is accurate to better that 10 percent. For winter conditions, however, the model underpredicts the observed relative diurnal variation by a factor of 2; a major part of this discrepancy is due to an observed postmidnight increase in ozone. Various suggested changes in model parameters to better produce the ozone abundance vertical profile result in only small differences in the relative diurnal variation, indicating that these observations do not provide a sensitive test of the mesospheric chemistry controlling the abundance of odd oxygen.

  19. Atomic Oxygen and Energy Balance in the Mesosphere and Lower Thermosphere

    NASA Astrophysics Data System (ADS)

    Mlynczak, M. G.; Hunt, L. A.; Marshall, T.; Mertens, C. J.; Russell, J. M.; Mast, J. C.; Thompson, R. E.

    2012-12-01

    We use atomic oxygen concentrations measured by SABER in conjunction with measurements of infrared radiative cooling and solar heating to assess the energy balance in the Earth's mesosphere and lower thermosphere. Atomic oxygen plays a central role, particularly in the mesopause region, through heating due to exothermic chemical reactions. The SABER data reveal approximate balance in global heating and cooling on annual timescales. In the 11-year SABER record there is also clear evidence of the solar cycle variation in all of the heat budget terms including atomic oxygen. Long-term changes in heating and cooling rates appear consistent with each other. Uncertainty in the energy budget is due largely to uncertainty in recombination rate coefficients governing exothermic chemical reactions at mesospheric temperatures. In this talk we will show the multitude of energy budget terms derived from SABER observations, the global energy budget, the variability due to the solar cycle, and the uncertainty in the energy balance. We also examine the constraints on the global atomic oxygen concentration based on energy balance considerations.

  20. Variability of mesospheric diurnal tides and tropospheric diurnal heating during 1997-1998

    NASA Astrophysics Data System (ADS)

    Lieberman, R. S.; Riggin, D. M.; Ortland, D. A.; Nesbitt, S. W.; Vincent, R. A.

    2007-10-01

    This study focuses on interannual variations of diurnal tropospheric heating and the response in the mesosphere observed by radars and predicted by a model. The work is prompted by reports of interannual variability in amplitudes of tidal variables at low latitudes. Diurnal tides observed at Hawaii and Christmas Island exhibit a pronounced ``spike'' in amplitude from late 1997 to early 1998. It has been speculated that this variability may be linked to the El Niño-Southern Oscillation phenomenon. We examine diurnal solar heating due to water vapor absorption, and diurnal latent heat release due to deep convection between 1988 and 2005. Both of these heating drives exhibit anomalously higher amplitudes in the tropical central and eastern Pacific during 1997-1998. The altered heating patterns result in a stronger forcing of the migrating diurnal tide by water vapor heating, and excitation of several weaker nonmigrating modes by latent heating. A primitive equation model is used to evaluate how these drives contribute to diurnal winds in the mesosphere. Anomalous water vapor heating results in about 15% increases in model meridional wind amplitudes over climatological values at subtropical latitudes between 300°E and the Greenwich meridian. While the timing of the model amplitude enhancements is consistent with observations at Hawaii, the observed increases are significantly stronger. Our study indicates that water vapor heating is the larger contributor to tidal enhancement observed during 1997-1998.

  1. Investigating planetary wave and seasonal variability in mesospheric temperature at mid- and low-latitudes

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Taylor, M.; Gardner, C.; Liu, A.

    The Utah State University Mesospheric Temperature Mapper MTM is a high performance CCD imaging system developed as part of the US CEDAR program This imager sequentially measures the nocturnal OH 6 2 band intensity and rotational temperature peak altitude sim 87km and the O 2 0 1 Atmospheric band intensity and temperature peak altitude sim 94km with a precision of 1-2 K in 3 minutes The MTM is capable of autonomous operation and since 1998 long-term seasonal measurements were obtained from the mid-latitude Starfire Optical Range SOR facility 35 r N NM duration 14 months Subsequently the imager was relocated to the low-latitude 21 r N at USAF AEOS facility at Maui Hawaii and long-term measurements were obtained as part of the Maui-MALT program 2001-2005 Over 500 nights of quality data have been obtained to date These measurements are constitute an important dataset for seasonal studies and were obtained in coordination with the University of Illinois Na wind temperature lidar which operated on a campaign basis from both of these facilities Together these two datasets have been used to investigate the occurrence and signatures of planetary waves and to compare seasonal variability in mesospheric temperature at mid- and low-latitudes

  2. Investigating Seasonal Oscillations in Mesospheric Temperatures at Low and Mid-latitudes

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Taylor, M. J.; Pautet, P.; Pugmire, J.; Pendleton, W. R.; Franke, S. J.; Scheer, J.

    2011-12-01

    The Andes Lidar Observatory (ALO) is a new upper atmospheric observatory located high in the Andes mountains at Cerro Pachón, Chile (30.3°S, 70.7°W, 2530 m). The Utah State University (USU) Mesospheric Temperature Mapper (MTM) was deployed in August, 2009 collocated with a Na wind/temperature lidar and meteor wind radar from University of Illinois at Urbana-Champaign (UIUC) and other optical instrumentation. Two years of high quality nocturnal OH (6, 2) and O2 (0, 1) band temperature and intensity data (centered at ~87 and 94 km, respectively) have now been obtained, enabling the first seasonal study from this southern hemispheric mountain site. In this presentation, we focus on the characteristics of the annual, semi-annual and other shorter term seasonal variability that we have identified in the temperature field (primary using the OH data) over the Andes, including their signatures in coincident radar wind data (same location) and additional mesospheric temperature data from nearby El Leoncito observatory (31.8°S, 69.3°W), Argentina. These results are compared with an earlier long-term study (2000-2005) using the MTM at Haleakala, Maui (20°N), as part of very successful Maui-MALT program.

  3. Seasonal Variability and Dynamics of Mesospheric Gravity Waves Over the Andes

    NASA Astrophysics Data System (ADS)

    Criddle, Neal; Taylor, Michael; Pautet, Dominique; Zhao, Yucheng

    2011-10-01

    The ALO is a new facility developed for atmospheric research, located at the foot of the Andes in Cerro Pachon, Chile (30.2 S, 70.7 W). As part of a collaborative program, Utah State has a mesospheric temperature mapper (MTM) on site, which is used to study short period gravity wave dynamics and temperature variations in the mesosphere-lower thermosphere region. The MTM began taking measurements of the OH(6,2) and O2(0,1) spectral bands in August 2009 and a complete profile of seasonal variation in gravity wave characteristics has been created for August 2009 through August 2010 using the OH(6,2) Band. The primary goal of this program is to Quantify seasonal variability of gravity wave structures. Compare and contrast seasonal directionality with results from the Maui-MALT site. Quantify mountain wave observations, their frequency, characteristics and seasonal variability. Seasonal variability for gravity wave structures at this site is shown. Mountain waves have been exclusively observed to appear in the winter months. Future work includes verifying yearly repeatability, which is seen at other sites, and continued investigation of unique events occurring over the Andes mountain range.

  4. Seasonal Investigation of Variance in Short Period Mesospheric Wave Structure at Low Latitudes.

    NASA Astrophysics Data System (ADS)

    Karnam, Hema; Taylor, Mike; Gunther, Jake

    2006-10-01

    As a part of the Maui-MALT program, the Utah State University Mesospheric Temperature Mapper (MTM) has operated continuously at Maui-Hawaii since November 2001. Over 1000 nights of high quality data on Mesospheric temperatures using the near infra red OH and O2 emission layers (centered at 87 and 94 km respectively) have been obtained over the past four years. In this study, we have analyzed data from 2003 (295 nights) to perform an initial investigation of the variance in OH and O2 signal in the frequency band corresponding to short period (12 min- 1 hour) . This was done by spectrally filtering the data into selected bands (approximately 1 hour wide). The data have been used to study variability in wave content on a night-to-night as well as a seasonal basis. Short period waves were present throughout the year and indicate no obvious summer to winter difference in wave power. On sporadic nights throughout the year, both OH and O2 show remarkable enhancements of wave power (factor of 10). Here, we present the results of this initial study.

  5. Global structure and seasonal variability of the migrating terdiurnal tide in the mesosphere and lower thermosphere

    NASA Astrophysics Data System (ADS)

    Yue, Jia; Xu, Jiyao; Chang, Loren C.; Wu, Qian; Liu, Han-Li; Lu, Xian; Russell, James

    2013-12-01

    The morphology of the migrating terdiurnal tide with zonal wavenumber 3 (TW3) in the mesosphere and lower thermosphere (MLT) is revealed using the TIMED satellite datasets from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) and the TIMED Doppler Interferometer (TIDI) instruments from 2002 to 2009, as well as the Thermosphere Ionosphere Mesosphere Electrodynamics General Circulation Model (TIME-GCM). The annual mean structures of the TW3 from the TIME-GCM clearly resemble the first real symmetric (3,3) Hough mode. The TW3 temperature and zonal wind components have three peaks at midlatitudes and near the equator, while the TW3 meridional wind components show four peaks at mid and low latitudes. These features are consistent with those resolved in SABER temperature and TIDI zonal wind above ~95 km. TW3 components in the TIME-GCM are stronger during winter and spring months at midlatitudes, which is in agreement with previous ground-based radar measurements. On the other hand, TW3 components of temperature, zonal and meridional winds from SABER and TIDI display different seasonal variations at different altitudes and latitudes. The results presented in this paper will provide an observational basis for further modeling study of terdiurnal tide impacts on the thermosphere and ionosphere.

  6. Longitudinal structure of the northern higher latitude middle stratosphere to lower mesosphere

    NASA Astrophysics Data System (ADS)

    Lastovicka, Jan; Krizan, Peter; Kozubek, Michal

    2016-07-01

    The meridional wind is relatively little studied but important quantity in the stratosphere and mesosphere. We found a two-core longitudinal structure in meridional wind at northern higher middle latitudes based on MERRA data. The two-core structure covers the middle stratosphere (lower boundary ~50 hPa), upper stratosphere and lower mesosphere (up to at least 0.1 hPa, probably somewhat higher). It is circulation response to the appearance of the blocking Aleutian pressure high, which affects more or less also the zonal wind, temperature and ozone fields. The well-pronounced two core structure occurs only in the winter half of the year (October-March) and only at the Northern Hemisphere. The two-core longitudinal structure in meridional wind is persistent feature. Only a few winters (Januaries) reveal more complex structure; all these winters were observed during the positive phase of the Pacific PNA index. The two core structure and Aleutian pressure high display a westward shift with increasing altitude, which allows the interpretation of the blocking Aleutian pressure high as a stationary planetary wave with the two core structure of meridional wind as a response of the overall circulation to the appearance of this stationary planetary wave in pressure field. Its existence could influence the Brewer-Dobson circulation and also the zonal mean approach to investigations of the middle atmosphere.

  7. Neutron Polarizers Based on Polarized 3He

    SciTech Connect

    William M. Snow

    2005-05-01

    The goal of this work, which is a collaborative effort between Indiana University, NIST, and Hamilton College, is to extend the technique of polarized neutron scattering into new domains by the development and application of polarized 3He-based neutron spin filters. After the IPNS experiment which measured Zeeman sp[litting in surface scattered neutrons using a polarized 3He cell as a polarization analyzer transporterd by car from Bloomington to Chicago, the Indiana work focused on technical developments to improve the 3He polarization of the Indiana compression system. The compression system was rebuilt with a new valve system which allows gas trapped in the dead volume of the compressors at the end of the piston stroke to be exhausted and conducted back to the optical pumping cell where it can be repolarized. We also incorporated a new intermediate storage volume made at NIST from 1720 glass which will reduce polarization losses between the compressors. Furthermore, we improved the stability of the 1083 nm laser by cooling the LMA rod. We achieved 60% 3he polarization in the optical pumping cell and 87% preservation of the polarization during compression. In parallel we built a magnetically-shielded transport solenoid for use on neutron scattering instruments such as POSY which achieves a fractional field uniformity of better than 10-3 per cm. The field was mapped using an automated 3D field mapping system for in-situ measurement of magnetic field gradients Diluted magnetic semiconductors offer many exciting opportunities for investigation of spintronic effects in solids and are certain to be one of the most active areas of condensed matter physics over then next several years. These materials can act as efficient spin injectors for devices that make use of spin-dependent transport phenomena. We just (late July 2002) finished a neutron reflectivity experiment at NIST on a GaMnAs trilayer film. This material is a ferromagnetic semiconductor which is of interest

  8. Imaging with polarized neutrons

    NASA Astrophysics Data System (ADS)

    Dawson, Martin; Manke, Ingo; Kardjilov, Nikolay; Hilger, André; Strobl, Markus; Banhart, John

    2009-04-01

    Neutrons have zero net electrical charge and can thus penetrate deeply into matter, but their intrinsic magnetic moment makes them highly sensitive to magnetic fields. These properties have been combined with radiographic (2D) and tomographic (3D) imaging methods to provide a unique technique to probe macroscopic magnetic phenomena both within and around bulk matter. Based on the spin-rotation of a polarized neutron beam as it passes through a magnetic field, this method allows the direct, real-space visualization of magnetic field distributions. It has been used to investigate the Meissner effect in a type I (Pb) and a type II (YBCO) superconductor, flux trapping in a type I (Pb) superconductor, and the electromagnetic field associated with a direct current flowing in a solenoid. The latter results have been compared to predictions calculated using the Biot-Savart law and have been found to agree well.

  9. The CSSL (combined sporadic structures and layers) payload: In situ observations of mesospheric sodium and related parameters

    NASA Technical Reports Server (NTRS)

    Machuga, David W.; Kane, Timothy J.; Wheeler, Timothy F.; Croskey, Charles L.; Mathews, John D.; Mitchell, John D.

    1997-01-01

    The objectives, design and results of the sensor systems for the combined sporadic structures and layers (CSSL) payload are analyzed. The CSSL main objectives were to: validate current models of mesospheric sodium chemistry; explore the relationship between turbulence and Na fluctuations; and to explore the relationship between high latitude electric fields and the formation of Na anomalies.

  10. Radar observations of high-latitude lower-thermospheric and upper-mesospheric winds and their response to geomagnetic activity

    SciTech Connect

    Johnson, R.M.

    1987-01-01

    Observations made by the Chatanika, Alaska, incoherent scatter radar during the summer months of 1976 to 1081 are analyzed to obtain high resolution lower-thermospheric neutral winds. Average winds and their tidal components are presented and compared to previous observational and model results. Upper-mesospheric neutral-wind observations obtained by the Poke Flat, Alaska Mesosphere-Stratosphere-Troposphere (MST) radar during the summer months of 1980 to 1982 are investigated statistically for evidence of variations due to geomagnetic activity. Observation of upper-mesospheric neutral winds made during two energetic Solar Proton Events (SPEs) by the Poker Flat, MST radar are presented. These results allow the low-altitude limits of magnetospheric coupling to the neutral atmosphere to be determined. Lower-thermospheric neutral winds are coupled to the ion convection driven by typical magnetospheric forcing above about 100 km. Coupling to lower atmospheric levels does not occur except during intervals of extreme disturbance of the magnetosphere-ionosphere-thermosphere system which are also accompanied by dramatically increased ionization in the high-latitude mesosphere, such as SPEs.

  11. Doppler Ducting of Quasi-Ripple Wave Events in the Mesospheric OH and O2 Airglow Emissions

    NASA Astrophysics Data System (ADS)

    Simkhada, D. B.; Taylor, M. J.; Franke, S. J.

    2007-12-01

    Short-lived (< 40 min) ripple events are common and well documented phenomena in the mesospheric airglow emissions. Recent coordinated studies have determined that these small-scale wave patterns are primarily due to instabilities processes as indicated by their Richardson number (Ri < 0.25, dynamic and Ri < 0, convective instability). These events are contrasted by the frequent occurrence of well-defined, much larger scale wave patterns, termed bands that are mainly associated with the passage of freely propagating short- period (< 1 hour) gravity waves through the upper mesosphere. Here we present new coordinated imaging and meteor radar measurements of spatially extensive ripple-like events that outwardly appear to be ripple but are not directly due to instability processes. The measurements were obtained as a part of the joint NSF/AFOSR Maui-MALT program using the Utah State University Mesospheric Temperature Mapper (MTM) sequentially sampling the OH and O2 airglow emissions centered at 87 and 94 km, respectively, and the University of Illinois meteor radar providing hourly wind measurements over the altitude range of 80-100 km. Using two years of data 2003-2004, we have identified 20 quasi-ripple events where the background wind measurements clearly show the events to be strongly Doppler ducted (or evanescent) in nature. These relatively rare events provide important new information on the dynamics of wave ducting at mesospheric heights.

  12. Circulation of mesosphere of Venus according to wind tracking results obtained from VMC and VIRTIS onboard Venus Express

    NASA Astrophysics Data System (ADS)

    Patsaeva, Marina; Khatuntsev, Igor; Ignatiev, Nikolay

    2012-07-01

    Six years of permanent monitoring of the Venus' cloud layer by the ESA spacecraft Venus Express (VEx) provided the opportunity to study dynamics of various mesospheric layers. UV images provided by the VMC allowed studying the circulation at the top cloud layer. 550 orbits covering about 10 Venusian years have been processed by means of an automated cloud tracking method giving 400000 displacement vectors. Average zonal and meridional wind profiles have been calculated, and vector fields of wind velocities in latitude-time coordinates have been built. The plots show that zonal and meridional wind velocities depend on local time. A diurnal wave of zonal wind velocity at the equatorial region can be seen clearly. It has maximum at 9 a.m. which is in good agreement with data obtained by the FS onboard Venera-15. The average wind velocity at the equator is 97±2 m/s. The period of zonal rotation has maximum (about 5 terrestrial days) at the equator and minimum (3 terrestrial days) at the latitude 50S. The visual cloud tracking method, due to better sensitivity to small image details at middle and high latitudes, shows a jet at the latitude 50S±3. Having maximum at 50S, the zonal wind velocity decreases to the South pole in linear fashion. The meridional wind velocity is about 0 m/s at the equator, increases in linear fashion to -10 m/s (the negative velocity represents the flow from the equator to the South pole) at 50S, and decreases to a low positive value at 75S. Within the equatorial region, up to 35S, the zonal wind velocity oscillates with a period about 4.83 days which is close to the super-rotation period at the equator. The average oscillation amplitude is 4.28 m/s and the maximum amplitude is 17.44 m/s. The oscillation amplitude of the zonal wind velocity depends on latitude. The oscillation amplitude and phase change with time, but can be stable as long as 70 days. VIRTIS images for the 1.27 μ m spectral band (molecular oxygen airglow), obtained at the

  13. Polarization Considerations

    NASA Technical Reports Server (NTRS)

    Waluschka, Eugene

    1998-01-01

    As light passes through a optical system the reflections and refractions will in general change the polarization state of the light. If we assume that all of the materials in the thin film coatings and substrate are isotropic and homogeneous then calculating the amount of "instrumental" polarization is a relatively straight forward task. In the following sections we will present a of the steps required to perform a 'polarization ray trace' calculation for a single ray and monochromatic and hence polarized light. The thin film portion of the calculation is also shown. The reason for explicitly showing the thin film equations is that there are sign conventions imposed on the boundary value equations by the orientation and handedness of the various coordinate frames which are attached to the geometric rays. The attenuation of light through a optical system, is relatively simple, and requires at the very least a lens (average) reflectivity or transmissivity. Determining the polarization sensitivity of a optical system is still relatively straight forward requiring at least a knowledge of the behavior of the "s" and "p" components at each interface for the chief ray. Determining the thin film induced aberrations of a optical system are somewhat more demanding. Questions about the arithmetic sign of the phase factors and how this relates to the overall "OPD" of a ray are ubiquitous. Many rays are required to construct a wavefront. Thin film codes which modify the OPD's of rays are a requirement for this last mentioned computation. This requires a consistent scheme of coordinate frames and sign conventions and is probably the most demanding task of a polarization ray trace. Only the electric field will used in the discussion. This is not a restriction as the Stokes parameters are functions of the electric field. The following does not attempt to explain, but only to present all of the required concepts and formulas.

  14. Solar Energy Deposition Rates in the Mesosphere Derived from Airglow Measurements: Implications for the Ozone Model Deficit Problem

    NASA Technical Reports Server (NTRS)

    Mlynczak, Martin G.; Garcia, Rolando R.; Roble, Raymond G.; Hagan, Maura

    2000-01-01

    We derive rates of energy deposition in the mesosphere due to the absorption of solar ultraviolet radiation by ozone. The rates are derived directly from measurements of the 1.27-microns oxygen dayglow emission, independent of knowledge of the ozone abundance, the ozone absorption cross sections, and the ultraviolet solar irradiance in the ozone Hartley band. Fifty-six months of airglow data taken between 1982 and 1986 by the near-infrared spectrometer on the Solar-Mesosphere Explorer satellite are analyzed. The energy deposition rates exhibit altitude-dependent annual and semi-annual variations. We also find a positive correlation between temperatures and energy deposition rates near 90 km at low latitudes. This correlation is largely due to the semiannual oscillation in temperature and ozone and is consistent with model calculations. There is also a suggestion of possible tidal enhancement of this correlation based on recent theoretical and observational analyses. The airglow-derived rates of energy deposition are then compared with those computed by multidimensional numerical models. The observed and modeled deposition rates typically agree to within 20%. This agreement in energy deposition rates implies the same agreement exists between measured and modeled ozone volume mixing ratios in the mesosphere. Only in the upper mesosphere at midlatitudes during winter do we derive energy deposition rates (and hence ozone mixing ratios) consistently and significantly larger than the model calculations. This result is contrary to previous studies that have shown a large model deficit in the ozone abundance throughout the mesosphere. The climatology of solar energy deposition and heating presented in this paper is available to the community at the Middle Atmosphere Energy Budget Project web site at http://heat-budget.gats-inc.com.

  15. Planetary-scale hydraulic jumps and transonic jet-streaks in the MACDA reanalysis of the Martian atmosphere: a comparison with Earth's lower mesosphere

    NASA Astrophysics Data System (ADS)

    Dowling, Timothy E.; Bradley, Mary Elizabeth; Lewis, Stephen R.; Read, Peter L.

    2016-10-01

    We have analyzed the Mars MACDA V1.0 global reanalysis on potential-temperature surfaces, θ, over the range θ = 400 to 900 K (~30 to ~60 km). The strongest seasonal wind, the northern-winter polar jet, exhibits two intriguing features: i) transonic jet streaks and ii) the juxtaposition of regions of shooting and tranquil flow, in the sense of Froude-number hydraulics, which suggests a planetary-scale hydraulic jump. Mesoscale bores have been studied on Mars, but to our knowledge the above two features have not been reported elsewhere. To characterize the basic state, we examine scatter plots of Ertel potential vorticity, Q, versus Bernoulli streamfunction, B, and fit the linear model Q/Q0 = 1 - μ0 (B-B0). In autumn, winter and spring, the nondimensionalized correlation parameter, μ'0 = (NH)2 μ0, in mid-latitudes is positive and nearly constant in time. Its value is close to unity at the bottom of the study region and gradually decreases with increasing θ (increasing altitude). In northern summer it swings negative. These attributes match Earth's lower mesosphere (θ = 2000 to 3000 K; ~48 to ~62 km). In southern summer, Ls ~ 270○, a hypsometric flaring of the θ layers, which is not seen in northern summer, is associated with the previously reported reduction of Q to approximately zero across the entire southern hemisphere and northern tropics. Between each winter polar jet and pole, especially in the north, there is a large spread of Q over a small domain of B, which is unlike Earth and may be related to the aforementioned hydraulic jump. We are currently examining 3D Lagrangian fluid trajectories to better characterize the rotating hydraulics of the system as a function of season.

  16. Short-term nonmigrating tide variability in the mesosphere, thermosphere, and ionosphere

    NASA Astrophysics Data System (ADS)

    Pedatella, N. M.; Oberheide, J.; Sutton, E. K.; Liu, H.-L.; Anderson, J. L.; Raeder, K.

    2016-04-01

    The intraseasonal variability of the eastward propagating nonmigrating diurnal tide with zonal wave number 3 (DE3) during 2007 in the mesosphere, ionosphere, and thermosphere is investigated using a whole atmosphere model reanalysis and satellite observations. The atmospheric reanalysis is based on implementation of data assimilation in the Whole Atmosphere Community Climate Model (WACCM) using the Data Assimilation Research Testbed (DART) ensemble Kalman filter. The tidal variability in the WACCM+DART reanalysis is compared to the observed variability in the mesosphere and lower thermosphere (MLT) based on the Thermosphere Ionosphere Mesosphere Energetics Dynamics satellite Sounding of the Atmosphere using Broadband Emission Radiometry (TIMED/SABER) observations, in the ionosphere based on Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) observations, and in the upper thermosphere (˜475 km) based on Gravity Recovery and Climate Experiment (GRACE) neutral density observations. To obtain the short-term DE3 variability in the MLT and upper thermosphere, we apply the method of tidal deconvolution to the TIMED/SABER observations and consider the difference in the ascending and descending longitudinal wave number 4 structure in the GRACE observations. The results reveal that tidal amplitude changes of 5-10 K regularly occur on short timescales (˜10-20 days) in the MLT. Similar variability occurs in the WACCM+DART reanalysis and TIMED/SABER observations, demonstrating that the short-term variability can be captured in whole atmosphere models that employ data assimilation and in observations by the technique of tidal deconvolution. The impact of the short-term DE3 variability in the MLT on the ionosphere and thermosphere is also clearly evident in the COSMIC and GRACE observations. Analysis of the troposphere forcing in WACCM+DART and simulations of the Global Scale Wave Model (GSWM) show that the short-term DE3 variability in the MLT is

  17. Magnetic excitations and polarized neutrons

    SciTech Connect

    Shirane, G.

    1985-01-01

    We review the historical development of polarized beam techniques for studies of condensed matter physics. In particular we describe, in some detail, the recent advance of the triple axis technique with polarization analysis. It is now possible to carry out quantitative characterization of magnetic cross sections S(Q,..omega..), in absolute units, for a wide range of energy and momentum transfers. We will discuss some examples of recent inelastic measurements on 3d ferromagnets and heavy Fermions. 35 refs., 11 figs., 2 tabs.

  18. Flight experience of solar mesosphere explorer's power system over high temperatures ranges

    NASA Technical Reports Server (NTRS)

    Faber, Jack; Hurley, Daniel

    1987-01-01

    The performance of the power system on the Solar Mesosphere Explorer (SME) satellite for the life of the mission and the techniques used to ensure power system health are summarized. Early in the mission high cell imbalances in one of the batteries resulted in a loading scheme which attempted to minimize the cell imbalances without causing an undervoltage condition. A short term model of the power system allowed planners to predict depth of discharge using the latest available data. Due to expected orbital shifts the solar arrays experience extended periods of no eclipse. This has required special conditioning schemes to keep the batteries healthy when the eclipses return. Analysis of the SME data indicates long term health of the SME power system as long as the conditioning scheme is continued.

  19. Mesospheric nightglow spectral survey taken by the ISO spectral spatial imager on ATLAS 1

    NASA Technical Reports Server (NTRS)

    Owens, J. K.; Torr, D. G.; Torr, M. R.; Chang, T.; Fennelly, J. A.; Richards, P. G.; Morgan, M. F.; Baldridge, T. W.; Fellows, C. W.; Dougani, H.

    1993-01-01

    This paper reports the first comprehensive spectral survey of the mesospheric airglow between 260 and 832 nm taken by the Imaging Spectrometric Observatory on the ATLAS 1 mission. We select data taken in the spectral window between 275 and 300 nm to determine the variation with altitude of the Herzberg I bands originating from the vibrational levels v-prime = 3 to 8. These data provide the first spatially resolved spectral measurements of the system. The data are used to demonstrate that to within an uncertainty of +/- 10 percent, the vibrational distribution remains invariant with altitude. The deficit reported previously for the v-prime = 5 level is not observed although there is a suggestion of depletion in v-prime = 6. The data could be used to place tight constraints on the vibrational dependence of quenching rate coefficients, and on the abundance of atomic oxygen.

  20. Mesospheric nightglow spectral survey taken by the ISO spectral spatial imager on Atlas 1

    NASA Technical Reports Server (NTRS)

    Owens, J. K.; Torr, D. G.; Torr, M. R.; Chang, T.; Fennelly, J. A.; Richards, P. G.; Morgan, M. F.; Baldridge, T. W.; Dougani, H.; Swift, W.

    1993-01-01

    This paper reports the first comprehensive spectral survey of the mesospheric airglow between 260 and 832 nm taken by the Imaging Spectrometric Observatory (ISO) on the ATLAS I mission. We select data taken in the spectral window between 275 and 300 nm to determine the variation with altitude of the Herzberg I bands originating from the vibrational levels v' = 3 to 8. These data provide the first spatially resolved spectral measurements of the system. The data are used to demonstrate that to within an uncertainty of + 10%, the vibrational distribution remains invariant with altitude. The deficit reported previously for the v' = 5 level is not observed although there is a suggestion of depletion in v' = 6. The data could be used to place tight constraints on the vibrational dependence of quenching rate coefficients, and on the abundance of atomic oxygen.

  1. Characteristics of Thunderstorms and Lightning Flashes Which Produce Mesospheric Transient Luminous Events

    NASA Technical Reports Server (NTRS)

    Lyons, W. A.; Nelson, T. E.; Armstrong, R. A.; Williams, E. R.; Suszcynsky, D. M.; Strabley, R.; Taylor, M.; Gardner, L.

    1999-01-01

    A six year record of optical observations of lightning-induced mesospheric transient luminous events (TLEs) is available from the Yucca Ridge Field Station (YRFS) near Ft. Collins, CO. Climatological analyses reveal sprites and elves occur in a variety of convective storm types, but principally mesoscale convective systems (MCSs) and squall lines. Severe supercell storms rarely produce TLEs, except during their dissipating stage. Few TLEs are observed during storms with radar echo areas <7,500 sq km. Above this size there is a modest correlation with radar areal coverage. A typical High Plains storm produces 45 TLEs over a 143 interval. Sprites and most elves are associated with +CGs. The probability of a TLE increases with peak current. In six storms, 5.1% of +CGs produced TLEs, the number increasing to 32% of +CGs with >75 kA and 52% of +CGs with >100 kA peak current.

  2. Payload charging events in the mesosphere and their impact on Langmuir type electric probes

    NASA Astrophysics Data System (ADS)

    Bekkeng, T. A.; Barjatya, A.; Hoppe, U.-P.; Pedersen, A.; Moen, J. I.; Friedrich, M.; Rapp, M.

    2013-02-01

    Three sounding rockets were launched from Andøya Rocket Range in the ECOMA campaign in December 2010. The aim was to study the evolution of meteoric smoke particles during a major meteor shower. Of the various instruments onboard the rocket payload, this paper presents the data from a multi-Needle Langmuir Probe (m-NLP) and a charged dust detector. The payload floating potential, as observed using the m-NLP instrument, shows charging events on two of the three flights. These charging events cannot be explained using a simple charging model, and have implications towards the use of fixed bias Langmuir probes on sounding rockets investigating mesospheric altitudes. We show that for a reliable use of a single fixed bias Langmuir probe as a high spatial resolution relative density measurement, each payload should also carry an additional instrument to measure payload floating potential, and an instrument that is immune to spacecraft charging and measures absolute plasma density.

  3. Diurnal Changes of The Ion Densities In The Undisturbed Mesosphere and Lower Thermosphere

    NASA Astrophysics Data System (ADS)

    Kazil, J.; Kopp, E.; Chabrillat, S.; Bishop, J.

    Ions are produced in the undisturbed atmosphere by solar X-ray and EUV radiation and by Galactic Cosmic Rays. The production from cosmic rays is constant throughout the day, whereas the production from solar radiation depends on the solar zenith angle. In addition, direct sunlight interacts with the ions and affects the ion chemistry. At night, below approximately 80km, there is no significant contribution to the ion production from solar light. Above this level (up to approximately 160km), scattered solar Lyman- and - radiation is the main nighttime source for ions. We use the University of Bern Atmospheric Ion Model (UBAIM), fed with neutral data from the NCAR SOCRATES model, with solar flux data from the SOLAR2000 model, and with numerical nighttime Lyman- and - fluxes to investigate the diurnal changes of the ion densities in the undisturbed mesosphere and lower thermosphere (50-120km log-p altitude).

  4. A further study of gravity wave induced drag and diffusion in the mesosphere

    NASA Technical Reports Server (NTRS)

    Holton, J. R.; Zhu, X.

    1984-01-01

    Lindzen's (1967) parameterization for the drag and eddy diffusion produced by breaking internal gravity waves in the mesosphere and lower thermosphere is applied to a modified version of the beta-plane channel model of Holton (1982) in which an isotropic source spectrum of waves is specified similar to that given in 1982 by Matsuno (1982). The transmission for each wave component is influenced by Newtonian cooling and by eddy diffusion induced by the breaking of other wave components. In general the waves with smallest Doppler-shifted phase speeds break first and produce sufficient eddy diffusion to significantly raise the breaking heights for the higher speed components. Thus, the wave drag and diffusion is spread through a deep layer and the resulting mean wind profiles for both summer and winter solstice conditions are more realistic than those computed previously by Holton.

  5. The role of gravity wave induced drag and diffusion in the momentum budget of the mesosphere

    NASA Technical Reports Server (NTRS)

    Holton, J. R.

    1982-01-01

    A slight modification of the parameterization suggested by Lindzen (1981) for the zonal drag and eddy diffusion effects generated by breaking internal gravity waves in the mesosphere is tested using a severely truncated midlatitude beta-plane channel model. It is found that realistic mean zonal flow profiles with zonal wind reversals above the mesopause can be simulated for both winter and summer radiative heating conditions provided that a gravity-wave spectrum is assumed which includes both stationary waves and waves of relatively large phase speeds. These results contrast greatly with the unrealistic mean wind profiles produced when Rayleigh friction is used to parameterize the effects of small scale motions on the mean flow.

  6. Properties of water vapor relevant to its measurement in the stratosphere and mesosphere

    NASA Technical Reports Server (NTRS)

    Longbothum, R. L.

    1974-01-01

    The literature on the concentrations of water vapor in the stratosphere and mesosphere was studied. It is estimated that the concentrations in these lie in the range from 0.1 ppm to 10 ppm. A survey was made of the scattering and radiative transfer properties of water vapor and the background constituents to determine the physical properties of importance to measurements of concentrations. It was determined that absorption and emission properties provide significant increases in sensitivity compared with the various scattering phenomena considered. Microwave absorption in the region of 22 GHz and 183 GHz and infrared absorption in the vibrational rotational band systems seem to be the most attractive techniques. Various experimental configurations are analyzed and compared.

  7. Remote sensing of mesospheric winds with the High-Resolution Doppler Imager

    NASA Technical Reports Server (NTRS)

    Hays, Paul B.; Abreu, V. J.; Burrage, M. D.; Gell, D. A.; Grassi, H. J.; Marshall, A. R.; Morton, Y. T.; Ortland, D. A.; Skinner, W. R.; Wu, D. L.

    1992-01-01

    Observations of the winds in the upper atmosphere obtained with the High-Resolution Doppler Imager (HRDI) on the Upper Atmosphere Research Satellite (UARS) are discussed. This instrument is a very stable high-resolution triple-etalon Fabry-Perot interferometer, which is used to observe the slight Doppler shifts of absorption and emission lines in the O2 Atmospheric bands induced by atmospheric motions. Preliminary observations indicate that the winds in the mesosphere and lower thermosphere are a mixture of migrating and non-migrating tides, and planetary-scale waves. The mean meridional winds are dominated by the 1,1 diurnal tide which is easily extracted from the daily zonal means of the satellite observations. The daily mean zonal winds are a mixture of the diurnal tide and a zonal flow which is consistent with theoretical expectations.

  8. Mesoscale density variability in the mesosphere and thermosphere: Effects of vertical flow accelerations

    NASA Technical Reports Server (NTRS)

    Revelle, D. O.

    1987-01-01

    A mechanistic one dimensional numerical (iteration) model was developed which can be used to simulate specific types of mesoscale atmospheric density (and pressure) variability in the mesosphere and the thermosphere, namely those due to waves and those due to vertical flow accelerations. The model was developed with the idea that it could be used as a supplement to the TGCMs (thermospheric general circulation models) since such models have a very limited ability to model phenomena on small spatial scales. The simplest case to consider was the integration upward through a time averaged, height independent, horizontally divergent flow field. Vertical winds were initialized at the lower boundary using the Ekman pumping theory over flat terrain. The results of the computations are summarized.

  9. Retrieval of metal atom and ion number densities in the mesosphere and lower thermosphere

    NASA Astrophysics Data System (ADS)

    Langowski, Martin; Von Savigny, Christian; Burrows, John

    2016-07-01

    When meteoroids enter the Earth's atmosphere with velocities of several 10 km/s, they heat up due to frictional heating and meteoric material is ablated in the upper atmosphere at around 100 km. A certain part of this ablated material are metal atoms and ions, which form layers of about 10 km width at altitudes between 80 to 110 km. The metal atoms and ions are strong emitters of dayglow coming from resonance fluorescence. From satellite observations of these emission signature, densities of the metal atom and ion layers can be retrieved. From the densities of the metal layers in combination with model simulations the input rate of meteoric material can be estimated, which still shows a large uncertainty range between 1 to 300 tons per day. We will present results of the number density retrievals from the SCIAMACHY limb mesosphere and lower thermosphere measurements from 2008 to 2012 for Mg, Mg^{+} and Na.

  10. Density response of the mesospheric sodium layer to gravity wave perturbations

    NASA Technical Reports Server (NTRS)

    Shelton, J. D.; Gardner, C. S.; Sechrist, C. F., Jr.

    1980-01-01

    Lidar observations of the mesospheric sodium layer often reveal wavelike features moving through the layer. It is often assumed that these features are a layer density response to gravity waves. Chiu and Ching (1978) described the approximate form of the linear response of atmospheric layers to gravity waves. In this paper, their results are used to predict the response of the sodium layer to gravity waves. These simulations are compared with experimental observations and a good correlation is found between the two. Because of the thickness of the sodium layer and the density gradients found in it, a linear model of the layer response is not always adequate to describe gravity wave-sodium layer interactions. Inclusion of nonlinearities in the layer response is briefly discussed. Experimental data is seen to contain features consistent with the predicted nonlinearities.

  11. Radiative forcing of the Venus mesosphere. I - Solar fluxes and heating rates

    NASA Technical Reports Server (NTRS)

    Crisp, D.

    1986-01-01

    A radiative-transfer model has been used to derive the structure and amplitude of the solar fluxes and heating rates in the Venus mesosphere, accounting for absorption and scattering extinction sources that encompass CO2, H2O, SO2, and H2SO4 aerosols as well as an unidentified UV absorber. The unknown substance that causes the observed cloud-top UV contrasts is responsible for most of the absorption of sunlight within the upper cloud deck; this contributes to solar heating rates of the order of 6 K/day at levels near 65 km. These results are judged sufficiently reliable for use in numerical dynamical models of the Venus atmosphere.

  12. Characterization of SO2 abundance in Venus' night-side mesosphere from SPICAV/VEX observations

    NASA Astrophysics Data System (ADS)

    Belyaev, Denis; Fedorova, Anna; Piccialli, Arianna; Marcq, Emmanuel; Montmessin, Franck; Bertaux, Jean-Loup; Evdokimova, Daria

    Sulfur dioxide (SO _{2}) is a key component of Venus’ atmosphere since the planet is totally covered by H _{2}SO _{4} droplets clouds at altitudes 50-70 km. Any significant change in the SO _{x} oxides above and within the clouds affects the photochemistry in the mesosphere (70-120 km). Recent continuous observations from the Venus Express orbiter (Belyaev et al., 2012; Marcq et al., 2013) and ground-based telescopes (Sandor et al., 2010; Krasnopolsky, 2010; Encrenaz et al., 2012) showed high variability of SO _{2} abundance with years, diurnal time and latitude on the day-side and terminators (commonly from 20 to 500 ppbv above the clouds). In the night-side mesosphere SO _{2} is not photo dissociative but, so far, its behavior has never been explored in details. In this paper we present first results from sulfur dioxide observations made by SPICAV UV spectrometer onboard Venus Express orbiter in regime of stellar occultation (Bertaux et al., 2007). In this mode the instrument observes night-side mesosphere and can register SO _{2} absorption bands in 190-220 nm and CO _{2} bands in 120-200 nm at altitudes from 85 to 110 km (spectral resolution is ˜2 nm). As a result, vertical distribution of SO _{2} and CO _{2} concentrations has been retrieved in observation period from June 2006 to April 2012, at latitude range 60(°) S-60(°) N and Venus local time 20:00-04:00. On the average, mixing ratio of sulfur dioxide fluctuates around ˜100 ppbv along altitude range 90-100 km. Our work is supported by the Program №22 of RAS and grant of the Russian Government to MIPT. References: Belyaev D. et al., 2012. Vertical profiling of SO _{2} and SO above Venus' clouds by SPICAV/SOIR solar occultations. Icarus 217, 740-751. Bertaux J.-L. et al., 2007. SPICAV on Venus Express: three spectrometers to study the global structure and composition of Venus atmosphere. Planet. Space Sci. 55, 1673-1700. Encrenaz T. et al., 2012. HDO and SO _{2} thermal mapping on Venus: evidence for

  13. Mesosphere and Lower Thermosphere Winds from space: A decade and a half of observations

    NASA Astrophysics Data System (ADS)

    Skinner, W. R.; Niciejewski, R.; Gell, D. A.; Cooper, M.; Marshall, A. R.; Solomon, S. C.; Wu, Q.; Killeen, T. L.; Ortland, D. A.

    2006-05-01

    Continuous space borne observations of the mesosphere and lower thermosphere wind field have now been made for more than 14 years. Wind measurements commenced in late 1991 with two wind sensing instrument on the UARS spacecraft (HRDI and WINDII) and continue to the present with the TIDI instrument on TIMED. The HRDI and WINDII instruments operated simultaneously during much of the operational life of UARS and have been extensively validated. Both TIDI and HRDI obtained measurements from 2002 to 2005 providing a very desirable three year overlap to cross calibrate the instruments. The length of this combined data set permits study of the inter-annual variability of this part of the atmosphere. This paper discusses some of longer term phenomena that have been studied.

  14. A global analysis of the ozone deficit in the upper stratosphere and lower mesosphere

    NASA Technical Reports Server (NTRS)

    Eluszkiewicz, Janusz; Allen, Mark

    1993-01-01

    The global measurements of temperature, ozone, water vapor, and nitrogen dioxide acquired by the Limb Infrared Monitor of the Stratosphere (LIMS), supplemented by a precomputed distribution of chlorine monoxide, are used to test the balance between odd oxygen production and loss in the upper stratosphere and lower mesosphere. An efficient photochemical equilibrium model, whose validity is ascertained by comparison with the results from a fully time-dependent one-dimensional model at selected latitudes, is used in the calculations. The computed ozone abundances are systematically lower than observations for May 1-7, 1979, which suggests, contrary to the conclusions of other recent studies, a real problem in model simulations of stratospheric ozone.

  15. Dynamics of the equatorial mesosphere: First results with a new generation partial reflection radar

    SciTech Connect

    Vincent, R.A.; Lesicar, D. )

    1991-05-01

    The first observations of mesospheric winds made between January-August 1990 with an MF partial reflection radar located on Christmas Island (2{degree}N, 157{degree}W) in the central Pacific are described. The mean zonal winds are in general westward, but show clear evidence for a wave-driven circulation. Power spectral studies indicate that waves are present over a wide range of periods. Ultra-fast Kelvin waves are especially evident in January-March, with peak amplitudes {approximately}20 ms{sup {minus}1}, and intrinsic phase speeds of {approximately}150 ms{sup {minus}1} indicated. The Kelvin waves are estimated to contribute an eastward acceleration of up to 10 ms{sup {minus}1} day{sup {minus}1}. Gravity wave amplitudes are also found to be almost as large as those observed at mid-latitude sites, which suggests that convection is a major source of gravity wave activity.

  16. Consequences of the Superposition of Tidal Components on the Dynamics of the Mesosphere and Lower Thermosphere

    NASA Astrophysics Data System (ADS)

    Ward, W. E.; Das, U.; Du, J.

    2014-12-01

    It is now generally accepted that the superposition of tidal components results in geographic variations in their observed amplitudes in the mesosphere and lower thermosphere (MLT). This superposition also has implications for the dynamical and convective stability of the atmosphere at these heights. Spatial variations in the amplitude of the temperature and vertical displacement also have consequences for chemistry and chemical heating in this region. In this paper, these superposition effects are explored using diagnosed fields from the extended Canadian Middle Atmosphere Model and CMAM30. The nature and distribution of wind and temperature variability, the associated instabilities and chemical heating are discussed. Superposition effects have consequences for tidal dissipation and gravity wave propagation in the MLT. They also may be a cause for some of the inversion layers observed in this region of the atmosphere.

  17. HHSMT observations of the Venusian mesospheric temperature, winds, and CO abundance around the MESSENGER flyby

    NASA Astrophysics Data System (ADS)

    Rengel, Miriam; Hartogh, Paul; Jarchow, Christopher

    2008-11-01

    We present submillimeter observations of 12CO J=3-2 and 2-1, and 13CO J=2-1 lines of the Venusian mesosphere and lower thermosphere with the Heinrich Hertz Submillimeter Telescope (HHSMT) taken around the second MESSENGER flyby of Venus on 5 June 2007. The observations cover a range of Venus solar elongations with different fractional disk illuminations. Preliminary results like temperature and CO abundance profiles are presented. These data are part of a coordinated observational campaign in support of the ESA Venus Express mission. Furthermore, this study attempts to contribute to cross-calibrate space- and ground-based observations, to constrain radiative transfer and retrieval algorithms for planetary atmospheres, and to a more thorough understanding of the global patters of circulation of the Venusian atmosphere.

  18. Radar observations of the quarterdiurnal tide in the mesosphere/lower thermosphere

    NASA Astrophysics Data System (ADS)

    Jacobi, Christoph; Krug, Amelie; Lilienthal, Friederike; Lima, Lourivaldo; Merzlyakov, Eugeny

    2016-04-01

    While the diurnal, semidiurnal and terdiurnal tides in the mesosphere/lower thermosphere (MLT) have been observed from the ground and from satellites, the quarterdiurnal tide has been investigated on a few occasions only. Therefore, meteor radar observations of horizontal winds in the MLT (80-100 km) at Collm (51.1°N, 13.0°E), Obninsk (55°N, 37°E), Cariri (7.4°S, 36.5°W) and Cachoeira Paulista (22.7°S, 45.0°W) have been used to analyse the seasonal variability of the quarterdiurnal tide at middle and low latitudes. At Collm and Obninsk, the zonal amplitudes show a clear maximum in boreal winter and a weaker one during spring. Amplitudes increase with height, with up to 7 m/s in the lower thermosphere. The meridional amplitudes are weaker, but show a similar seasonal cycle. Amplitudes and phases at Collm and Obninsk are similar, indicating that most of the observed 6-hour oscillation at higher midlatitudes is due to the migrating quarterdiurnal tide. Obninsk amplitudes show an interdecadal variation with smaller values during the 1990s and larger ones during the 2000s. At low southern latitudes over Cariri, the maxima during boreal winter and spring are also visible, but there is another one during austral winter, and generally the amplitudes are smaller. Meridional amplitudes at Cariri are larger than the zonal ones, and maximize during austral winter. At Cachoeira Paulista there are two maxima at the upper altitudes during the equinoxes in both wind components, and another one during austral winter in the mesosphere, which is mainly visible in the zonal component.

  19. The mesospheric sodium layer as a remotely, optically pumped magnetometer for investigation of Birkeland currents

    NASA Astrophysics Data System (ADS)

    Johnsen, Magnar G.; Matzka, Jürgen; Hoppe, Ulf-Peter

    2016-04-01

    By means of optical pumping, it is possible to use the naturally occurring sodium layer in the mesosphere to measure Earth's scalar magnetic field at ~90 km above ground. This is an altitude not accessible by other means than rockets, which only will provide point measurements of very short time scales. We are planning to modify the sodium lidar at ALOMAR in Northern Norway to be able, for the first time, to measure and monitor the magnetic field in situ in the high latitude mesosphere over longer time scales. The planned modifications to the lidar instrument will allow alternating between the new magnetometer mode and its present mode for atmospheric temperatures and winds. The technique, which has been proposed earlier for measurements at low or mid-latitudes for studies of Earth's internal magnetic field, will in our project be applied to high latitudes in the auroral zone. This opens for a completely new domain of measurements of externally generated geomagnetic variations related to currents in the magnetosphere-ionosphere system. In particular, we aim to measure the magnetic field variations in close vicinity to Birkeland currents associated with particle precipitation events penetrating to altitudes below 90 km and small-scale, discrete auroral arcs. It is, furthermore, anticipated that it will be possible to detect horizontal current structures in the E-layer on much smaller length scales than it is presently possible from ground observations alone. During the project we plan take advantage of the rich space science infrastructure located in northern Norway, including ALOMAR, EISCAT and the Tromsø Geophysical Observatory magnetometer network. If possible, we also aim to make measurements in conjunction with overpasses of the SWARM satellites.

  20. High-resolution lidar observations of mesospheric sodium and implications for adaptive optics.

    PubMed

    Pfrommer, Thomas; Hickson, Paul

    2010-11-01

    Observations of sodium density variability in the upper mesosphere/lower thermosphere, obtained using a high-resolution lidar system, show rapid fluctuations in the sodium centroid altitude. The temporal power spectrum extends above 1 Hz and is well-fit by a power law having a slope that is -1.95±0.12. These fluctuations produce focus errors in adaptive optics systems employing continuous-wave sodium laser guide stars, which can be significant for large-aperture telescopes. For a 30 m aperture diameter, the associated rms wavefront error is approximately 4 nm per meter of altitude change and increases as the square of the aperture diameter. The vertical velocity of the sodium centroid altitude is found to be ~23 ms(-1) on a 1 s time scale. If these high-frequency fluctuations arise primarily from advection of horizontal structure by the mesospheric wind, our data imply that variations in the sodium centroid altitude on the order of tens of meters occur over the horizontal scales spanned by proposed laser guide star asterisms. This leads to substantial differential focus errors (~107 nm over a 1 arc min separation with a 30 m aperture diameter) that may impact the performance of wide-field adaptive optics systems. Short-lasting and narrow sodium density enhancements, more than 1 order of magnitude above the local sodium density, occur due to advection of meteor trails. These have the ability to change the sodium centroid altitude by as much as 1 km in less than 1 s, which could result in temporary disruption of adaptive optics systems.

  1. Mesospheric Non-Migrating Tides Generated With Planetary Waves. 1; Characteristics

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    We discuss results from a modeling study with our Numerical Spectral Model (NSM) that specifically deals with the non-migrating tides generated in the mesosphere. The NSM extends from the ground to the thermosphere, incorporates Hines' Doppler Spread Parameterization for small-scale gravity waves (GWs), and it describes the major dynamical features of the atmosphere including the wave driven equatorial oscillations (QBO and SAO), and the seasonal variations of tides and planetary waves. Accounting solely for the excitation sources of the solar migrating tides, the NSM generates through dynamical interactions also non-migrating tides in the mesosphere that are comparable in magnitude to those observed. Large non-migrating tides are produced in the diurnal and semi-diurnal oscillations for the zonal mean (m = 0) and in the semidiurnal oscillation for m = 1. In general, significant eastward and westward propagating tides are generated for all the zonal wave numbers m = 1 to 4. To identify the cause, the NSM is run without the solar heating for the zonal mean (m = 0), and the amplitudes of the resulting non-migrating tides are then negligibly small. In this case, the planetary waves are artificially suppressed, which are generated in the NSM through instabilities. This leads to the conclusion that the non-migrating tides are generated through non-linear interactions between planetary waves and migrating tides, as Forbes et al. and Talaat and Liberman had proposed. In an accompanying paper, we present results from numerical experiments, which indicate that gravity wave filtering contributes significantly to produce the non-linear coupling that is involved.

  2. Mesospheric CO2 Clouds at Mars: Seven Martian Years Survey by OMEGA/MEX

    NASA Astrophysics Data System (ADS)

    Gondet, Brigitte; Bibring, Jean-Pierre

    2016-04-01

    Mesospheric clouds have been detected first from Earth (Bell et al 1996 [1]), then from Mars orbit (MGS/TES and MOC, Clancy et al 1998 [2]). Their composition (CO2) was inferred from temperature. Similar detection and temperature-inferred composition was then performed by Spicam and PFS on board Mars Express (Monmessin et al [3], Formisano et al [4]. 2006). The first direct detection and characterization (altitude, composition, velocity) was performed by OMEGA/ Mars Express (then coupled to HRSC/ Mars Express, and confirmed by CRISM/MRO (Montmessin et al. [5], 2007, Maattanen et al [6]. Scholten et al. [7], 2010, Vincendon et al [8], 2011). Omega is a very powerful tool for the study of CO2 clouds as it is able to unambiguously identify the CO2 composition of a cloud based on a near-IR spectral feature located at 4.26 μm [5] Therefore since the beginning of the Mars Express mission (2004) OMEGA as done a systematic survey of these mesospheric clouds. Thanks to the orbit of Mars Express, we can observe this clouds from different altitudes (from apocenter to pericenter) and at different local times. We will present the result of 7 Martians years of observations, point out a correlation with the dust activity and an irregular concentration of clouds from years to years. References [1] JF Bell. et al. JGR 1996; [2] RT Clancy et al., GRL 1998 [3] F. Montmessin et al. JGR 2006; [4] V. Formisano et al., Icarus 2006; [5] F. Montmessin et al JGR 2007 [6] A. Määttänen et al. Icarus 2010; [7] F. Scholten et al. PSS 2010; [8] M. Viencendon et al. JGR 2011

  3. Observations of Altitude Dependence and Temporal Variation of ClO in the Venus Mesosphere

    NASA Astrophysics Data System (ADS)

    Sandor, Brad J.; Clancy, R. Todd

    2015-11-01

    Analysis of the first observations of ClO in the Venus mesosphere indicate ClO is present above 85 +/-3 km altitude and not below. The retrieved nightside mean abundances show a factor of 2 decrease between observation dates Oct. 23 and Nov. 11, 2015, with change between the two dates evident at more than two sigma confidence. Abundances and altitude distributions are retrieved from submm spectroscopic observations of the 352.88 GHz line of 35ClO (made with the James Clerk Maxwell Telescope - JCMT - located an Mauna Kea, Hawaii).Detection of ClO in the Venus atmosphere confirms a theory put forward by Yung and DeMore (1982) that the Venus atmosphere is stabilized as CO2 due to chlorine catalytic recombination of CO and O. (Without some form of catalysis, the Venus atmosphere would have 10s of percent CO and O2, but it is in fact 97% CO2 and 3% N2, with only trace amounts of CO and O2.) Detailed retrieval of ClO abundances and altitude distributions (the focus of this talk) provides greater insight to the catalytic process, and to other aspects of Venus atmospheric chlorine chemistry. We compare findings of our quantitave retrieval with predictions of photochemical models, and discuss the implications for chlorine photochemisty of the Venus atmosphere. We also discuss retrieved ClO temporal variation with that of upper mesospheric HCl (Sandor and Clancy, 2012).[We acknowledge funding of this project by NASA grants NNX10AB33G, NNX12AI32G, and NNX14AK05G, as well as NSF grant AST-1312985.

  4. Thermosphere-ionosphere-mesosphere energetics and dynamics (TIMED). The TIMED mission and science program report of the science definition team. Volume 1: Executive summary

    NASA Technical Reports Server (NTRS)

    1991-01-01

    A Science Definition Team was established in December 1990 by the Space Physics Division, NASA, to develop a satellite program to conduct research on the energetics, dynamics, and chemistry of the mesosphere and lower thermosphere/ionosphere. This two-volume publication describes the TIMED (Thermosphere-Ionosphere-Mesosphere, Energetics and Dynamics) mission and associated science program. The report outlines the scientific objectives of the mission, the program requirements, and the approach towards meeting these requirements.

  5. Cell polarity

    PubMed Central

    Romereim, Sarah M

    2011-01-01

    Despite extensive genetic analysis of the dynamic multi-phase process that transforms a small population of lateral plate mesoderm into the mature limb skeleton, the mechanisms by which signaling pathways regulate cellular behaviors to generate morphogenetic forces are not known. Recently, a series of papers have offered the intriguing possibility that regulated cell polarity fine-tunes the morphogenetic process via orienting cell axes, division planes and cell movements. Wnt5a-mediated non-canonical signaling, which may include planar cell polarity, has emerged as a common thread in the otherwise distinct signaling networks that regulate morphogenesis in each phase of limb development. These findings position the limb as a key model to elucidate how global tissue patterning pathways direct local differences in cell behavior that, in turn, generate growth and form. PMID:22064549

  6. Polar Diving

    NASA Technical Reports Server (NTRS)

    2006-01-01

    3 July 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layers exposed by erosion in a trough within the north polar residual cap of Mars, diving beneath a younger covering of polar materials. The layers have, since the Mariner 9 mission in 1972, been interpreted to be composed of a combination of dust and ice in unknown proportions. In this scene, a layer of solid carbon dioxide, which was deposited during the previous autumn and winter, blankets the trough as well as the adjacent terrain. Throughout northern spring, the carbon dioxide will be removed; by summer, the layers will be frost-free.

    Location near: 81.4oN, 352.2oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Spring

  7. Polar Summer

    NASA Technical Reports Server (NTRS)

    2005-01-01

    30 December 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows eroding mesas of frozen carbon dioxide in the martian south polar residual cap. During the summer season, the scarps that bound each pit and mesa in the south polar region become dark as carbon dioxide sublimes away. The darkening might result from the roughening of the surfaces from which ice is subliming, or from the concentration of trace amounts of dust on these slopes, or both.

    Location near: 84.7oS, 48.2oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  8. When matter matters

    SciTech Connect

    Easson, Damien A.; Sawicki, Ignacy; Vikman, Alexander E-mail: ignacy.sawicki@uni-heidelberg.de

    2013-07-01

    We study a recently proposed scenario for the early universe:Subluminal Galilean Genesis. We prove that without any other matter present in the spatially flat Friedmann universe, the perturbations of the Galileon scalar field propagate with a speed at most equal to the speed of light. This proof applies to all cosmological solutions — to the whole phase space. However, in a more realistic situation, when one includes any matter which is not directly coupled to the Galileon, there always exists a region of phase space where these perturbations propagate superluminally, indeed with arbitrarily high speed. We illustrate our analytic proof with numerical computations. We discuss the implications of this result for the possible UV completion of the model.

  9. A self-consistent model of halo/sprite influence on the chemical balance of the mesosphere

    NASA Astrophysics Data System (ADS)

    Mareev, E.; Kuterin, F.; Evtushenko, A.

    2013-12-01

    We develop one-dimensional plasma-chemical self-consistent model to describe influence of high altitude discharges - sprite and halo - on the chemical balance of the mesosphere. We take into account 25 neutrals including 9 excited chemical components, electrons, 24 positive ions, 11 negative ions, and use 267 chemical reactions [1,2] to describe chemical perturbation in the mesosphere. The electric field on the heights of mesosphere is determined as a solution of the differential equation depending on the conductivity of the mesosphere and the external electric field, which is created by uncompensated electric charge in the troposphere after the strong lightning discharge. Taking into account the high conductivity of the Earth's surface, we use the dipole approach for the external field. To get the electron temperature dependence on the reduced electric field, we use the freeware solver of Boltzmann equation BOLSIG+ [3]. Initial values of chemical components different from zero are obtained from the latest version (v5) of WACCM [4]. The results of modeling can be summarized as follows: Results for sprite. Maximum dipole moment of uncompensated charge 740 C×km was used. The discharge begins at the height 78 km several hundred microseconds after the beginning of electric current in a lightning channel in the troposphere and reaches a height of 70 km after one millisecond. The conductivity of mesosphere is reduced by practically 2 orders of magnitude at the beginning of the discharge (because of electron temperature and collision frequency increase), which may play a significant role for the discharge initiation. The perturbation of electron concentration reaches 500 cm-3, O2+ - 600 cm-3, H5O2+ - 500 cm-3, O2- - cm-3, and relaxation time is more than 100 s at the top of the sprite. Volume emission rate for first positive band of nitrogen reaches 2×108 cm-3s-1. Results for halo. There is no perturbation concentration of electrons and ions. The reduced elec-tric field

  10. A decrease in mesospheric water vapour detected in South-Korea in February 2008; from observation to interpretation.

    NASA Astrophysics Data System (ADS)

    de Wachter, Evelyn; Kaempfer, Niklaus; Flury, Thomas; Ka, Soohyun; Oh, Jung Jin

    Since November 2006, the University of Bern in Switzerland has been operating a ground-based microwave [GBMW] radiometer in Seoul, S-Korea [37.32N, 126.57E]. At the end of February 2008 we observed a significant decrease in mesospheric water vapour of more than 2 ppmv [around 40Trajectories were calculated and the temperature and wind field distribution in the northern hemisphere was analyzed. We validated the trajectory model results by a match tech-nique with other GBMW radiometer data from stations of the Network for the Detection of Atmospheric Composition Change [NDACC]. In addition, we investigated the possible impact of the major sudden stratospheric warming [SSW], which occured in February 2008 at midlat-itudes, to the mesospheric region, leaving signatures in the water vapour distribution at the observation site in Seoul.

  11. The photolysis of FeOH and its effect on the bottomside of the mesospheric Fe layer

    NASA Astrophysics Data System (ADS)

    Viehl, T. P.; Plane, J. M. C.; Feng, W.; Höffner, J.

    2016-02-01

    Metal layers in the upper mesosphere and lower thermosphere are created through meteoric ablation. They are important for understanding the temperature structure, dynamics, and chemistry of this atmospheric region. Recent lidar observations have shown a regular downward extension of the Fe layer bottomside which correlates with solar radiation. In this study we combine lidar observations, quantum chemical calculations, and model simulations to show that this bottomside extension is primarily caused by photolysis of FeOH. We determine the photolysis rate to be s-1. We also show that the reaction is slower at mesospheric temperatures than previous estimates. With these updated rate coefficients, we are able to significantly improve the modeling of the Fe layer bottomside. The calculations further show the nearly complete depletion of FeOH during sunlit periods. This may have implications for cloud nuclei in the middle atmosphere.

  12. Evidence of non-LTE Effects in Mesospheric Water Vapor from Spectrally-Resolved Emissions Observed by CIRRIS-1A

    NASA Technical Reports Server (NTRS)

    Zhou, D. K.; Mlynczak, M. G.; Lopez-Puertas, M.; Zaragoza, G.

    1999-01-01

    Evidence of non-LTE effects in mesospheric water vapor as determined by infrared spectral emission measurements taken from the space shuttle is reported. A cryogenic Michelson interferometer in the CIRRIS-1A shuttle payload yielded high quality, atmospheric infrared spectra. These measurements demonstrate the enhanced daytime emissions of H2O (020-010) which are the result of non-LTE processes and in agreement with non-LTE models. The radiance ratios of H2O (010 to 000) and (020 to 010) Q(1) transitions during daytime are compared with non-LTE model calculations to assess the vibration-to-vibration exchange rate between H2O and O2 in the mesosphere. An exchange rate of 1.2 x 10(exp -12)cc/s is derived.

  13. Polar Landforms

    NASA Technical Reports Server (NTRS)

    2005-01-01

    10 August 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows eroded remnants of carbon dioxide ice in the south polar residual cap of Mars. The scarps that outline each small mesa have retreated about 3 meters (10 feet) per Mars year since MGS began orbiting the red planet in 1997.

    Location near: 87.0oS, 31.9oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

  14. Polar Layers

    NASA Technical Reports Server (NTRS)

    2005-01-01

    12 August 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a slope upon which are exposed some of the layered materials that underlie the south polar cap of Mars. The layers are generally considered to be sediments--perhaps dust--that may have been cemented by water ice.

    Location near: 84.1oS, 343.9oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

  15. Effects of plasma particle trapping on dust-acoustic solitary waves in an opposite polarity dust-plasma medium

    SciTech Connect

    Ahmad, Zulfiqar; Mushtaq, A.; Mamun, A. A.

    2013-03-15

    Dust acoustic solitary waves in a dusty plasma containing dust of opposite polarity (adiabatic positive and negative dust), non-isothermal electrons and ions (following vortex like distribution) are theoretically investigated by employing pseudo-potential approach, which is valid for arbitrary amplitude structures. The propagation of small but finite amplitude solitary structures is also examined by using the reductive perturbation method. The basic properties of large (small) amplitude solitary structures are investigated by analyzing the energy integral (modified Korteweg-de Vries equation). It is shown that the effects of dust polarity, trapping of plasma particles (electrons and ions), and temperatures of dust fluids significantly modify the basic features of the dust-acoustic solitary structures that are found to exist in such an opposite polarity dust-plasma medium. The relevance of the work in opposite polarity dust-plasma, which may occur in cometary tails, upper mesosphere, Jupiter's magnetosphere, is briefly discussed.

  16. Polarization signatures of airborne particulates

    NASA Astrophysics Data System (ADS)

    Raman, Prashant; Fuller, Kirk A.; Gregory, Don A.

    2013-07-01

    Exploratory research has been conducted with the aim of completely determining the polarization signatures of selected particulates as a function of wavelength. This may lead to a better understanding of the interaction between electromagnetic radiation and such materials, perhaps leading to the point detection of bio-aerosols present in the atmosphere. To this end, a polarimeter capable of measuring the complete Mueller matrix of highly scattering samples in transmission and reflection (with good spectral resolution from 300 to 1100 nm) has been developed. The polarization properties of Bacillus subtilis (surrogate for anthrax spore) are compared to ambient particulate matter species such as pollen, dust, and soot. Differentiating features in the polarization signatures of these samples have been identified, thus demonstrating the potential applicability of this technique for the detection of bio-aerosol in the ambient atmosphere.

  17. Vertical profile of δ18OOO from middle stratosphere to lower mesosphere derived by retrieval algorithm developed for SMILES spectra

    NASA Astrophysics Data System (ADS)

    Sato, T. O.; Sagawa, H.; Yoshida, N.; Kasai, Y.

    2013-10-01

    Ozone is known to have large oxygen isotopic enrichments of about 10 % in the middle stratosphere, however, there have been no reports on ozone isotopic enrichments above the middle stratosphere. We derived an enrichment δ18OOO by a retrieval algorithm specified for the isotopic ratio from the stratosphere to the lower mesosphere based on observations from the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) onboard the International Space Station (ISS). The retrieval algorithm includes (i) an a priori covariance matrix constrained by oxygen isotopic ratios in ozone, (ii) an optimization of spectral windows for ozone isotopomers and isotopologues, and (iii) a common tangent height information for all windows. The δ18OOO obtained by averaging the SMILES measurements at the latitude range of 20° N to 40° N from February to March in 2010 with solar zenith angle <80° was 15% (at 32 km) and the systematic error was estimated to be about 5%. SMILES and past measurements were in good agreement with δ18OOO increasing with altitude between 30 and 40 km. The vertical profile of δ18OOO obtained in this study showed an increase and a decrease with altitude in the stratosphere and mesosphere, respectively. Stratopause is the peak-height of the δ18OOO value, and it rose to 18%. The δ18OOO has a positive correlation with temperature in the range of 220-255 K, indicating that temperature can be a dominant factor to control the vertical profile of δ18OOO in the stratosphere and mesosphere. This is the first report of the observation of δ18OOO over a wide range extending from the stratosphere to the mesosphere.

  18. Vertical profile of delta 18000 from middle stratosphere to lower mesosphere derived by retrieval algorithm developed for SMILES spectra

    NASA Astrophysics Data System (ADS)

    Kasai, Yasuko; Sato, Tomohiro; Sagawa, Hideo

    Ozone is known to have large oxygen isotopic enrichments of about 10% in the middle stratosphere, however, there have been no reports on ozone isotopic enrichments above the middle stratosphere. We derived an enrichment delta18OOO by a retrieval algorithm specified for the isotopic ratio from the stratosphere to the lower mesosphere based on observations from the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) onboard the International Space Station (ISS). The retrieval algorithm includes (i) an a priori covariance matrix constrained by oxygen isotopic ratios in ozone, (ii) an optimization of spectral windows for ozone isotopomers and isotopologues, and (iii) a common tangent height information for all windows. The delta18OOO obtained by averaging the SMILES measurements at the latitude range of 20N to 40N from February to March in 2010 with solar zenith angle less than 80(°) °was 15 % (at 32 km) and the systematic error was estimated to be about 5 percent. SMILES and past measurements were in good agreement with delta18OOO increasing with altitude between 30 and 40 km. The vertical profile of δ18OOO obtained in this study showed an increase and a decrease with altitude in the stratosphere and mesosphere, respectively. Stratopause is the peak-height of the delta18OOO value, and it rose to 18 %. The delta18OOO has a positive correlation with temperature in the range of 220-255 K, indicating that temperature can be a dominant factor to control the vertical profile of delta18OOO in the stratosphere and mesosphere. This is the first report of the observation of delta18OOO over a wide range extending from the stratosphere to the mesosphere.

  19. Limb Observations of Solar Scattered Light by the Imaging Ultraviolet Spectrograph on MAVEN: New Constraints on Martian Mesospheric Cloud Variability

    NASA Astrophysics Data System (ADS)

    Stevens, Michael H.; Siskind, David E.; Evans, Scott; Schneider, Nicholas M.; Stewart, A. Ian F.; Deighan, Justin; Jain, Sonal Kumar; Crismani, Matteo; Stiepen, Arnaud; Chaffin, Michael S.; McClintock, William; Holsclaw, Gregory; Lefevre, Franck; Montmessin, Franck; Lo, Daniel; Clarke, John T.; Jakosky, Bruce

    2016-10-01

    The Imaging Ultraviolet Spectrograph (IUVS) on NASA's Mars Atmosphere and Volatile Evolution (MAVEN) mission observed the Martian upper atmosphere in late 2015 (Ls ~ 70) and early 2016 (Ls ~ 150). Although designed to measure the dayglow between 90-200 km IUVS also scans the limb down to 60 km, where solar scattered light dominates the mid-ultraviolet (MUV) signal. Occasionally, this MUV light shows enhanced scattering between 60-90 km indicating the presence of aerosols in the mesosphere. We quantify the solar scattering for each daylight scan obtained between October and December, 2015 and between April and June, 2016. We then identify over 100 scans of enhanced scattering between 60-90 km and assemble them both geographically and diurnally. The geographical distribution of the enhancements in 2015 is preferentially located near the equator, consistent with previous observations of mesospheric clouds for this part of the season. A wave three pattern in equatorial cloud occurrence suggests forcing from a non-migrating tide, possibly linked to the longitudinal variation of Mars surface topography. At the same time, there are indications of a diurnal variation such that the clouds seen in 2015 and 2016 are preferentially observed in the early morning, between 0600-0900 local solar time. This suggests an important role for a migrating temperature tide controlling the formation of Martian mesospheric clouds.

  20. Radar Imaging of Equatorial Mesospheric Turbulence: A Case Study Using New Data from the Jicamarca Radar Observatory

    NASA Astrophysics Data System (ADS)

    Figg, E.; Lehmacher, G. A.

    2015-12-01

    Radar data from the mesosphere was collected with the Jicamarca Radio Observatory in Peru on May 10-11, 2011. The experiment used the full 300 m x 300 m antenna for transmission of 64-baud complementary pulses. The echoes were collected by the four north, south, east, and west quarters of the array with nominally 150 m range resolution. Then self spectra and cross spectra for different integration times were calculated from the complex voltage samples. Range time intensity (RTI) plots allow us to identify periods and regions of strong mesospheric echoes. At these locations, the coherence and phase of cross spectra were examined for pairs of the receiving channels. The slope of the interferometric phase angle allows the calculation of horizontal wind components. The recent experiment had a range resolution of 150 m which reveals details in the turbulent layers that could not be detected in a previous interferometry experiment with 1.5 km range resolution (Kudeki, JGR, 1988). We use the analysis to study the detailed motion in mesospheric echoes and search for individual scattering structures within the radar volume.

  1. MIPAS observations of longitudinal oscillations in the mesosphere and the lower thermosphere: climatology of odd-parity daily frequency modes

    NASA Astrophysics Data System (ADS)

    García-Comas, Maya; González-Galindo, Francisco; Funke, Bernd; Gardini, Angela; Jurado-Navarro, Aythami; López-Puertas, Manuel; Ward, William E.

    2016-09-01

    MIPAS global Sun-synchronous observations are almost fixed in local time. Subtraction of the descending and ascending node measurements at each longitude only includes the longitudinal oscillations with odd daily frequencies nodd from the Sun's perspective at 10:00. Contributions from the background atmosphere, daily-invariant zonal oscillations and tidal modes with even-parity daily frequencies vanish. We have determined longitudinal oscillations in MIPAS temperature with nodd and wavenumber k = 0-4 from the stratosphere to 150 km from April 2007 to March 2012. To our knowledge, this is the first time zonal oscillations in temperature have been derived pole to pole in this altitude range from a single instrument. The major findings are the detection of (1) migrating tides at northern and southern high latitudes; (2) significant k = 1 activity at extratropical and high latitudes, particularly in the Southern Hemisphere; (3) k = 3 and k = 4 eastward-propagating waves that penetrate the lower thermosphere with a significantly larger vertical wavelength than in the mesosphere; and (4) a migrating tide quasi-biennial oscillation in the stratosphere, mesosphere and lower thermosphere. MIPAS global measurements of longitudinal oscillations are useful for testing tide modeling in the mesosphere and lower thermosphere region and as a lower boundary for models extending higher up in the atmosphere.

  2. Polar Markings

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA02155 Polar Markings

    These bright and dark markings occurred near the end of summer in the south polar region. The dark material is likely dust that has been freed of frost cover.

    Image information: VIS instrument. Latitude -76.3N, Longitude 84.9E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  3. Polar Layers

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA02153 Polar Layers

    This image of the south polar region shows layered material. It is not known if the layers are formed yearly or if they form over the period of 10s to 100s of years or more.

    Image information: VIS instrument. Latitude -80.3N, Longitude 296.2E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  4. Polar Ridges

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03662 Polar Ridges

    This ridge system is located in the south polar region.

    Image information: VIS instrument. Latitude -81.7N, Longitude 296.5E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  5. Polar Textures

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03638 Polar Textures

    This image illustrates the variety of textures that appear in the south polar region during late summer.

    Image information: VIS instrument. Latitude 80.5S, Longitude 57.9E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  6. Polar ozone

    NASA Technical Reports Server (NTRS)

    Solomon, S.; Grose, W. L.; Jones, R. L.; Mccormick, M. P.; Molina, Mario J.; Oneill, A.; Poole, L. R.; Shine, K. P.; Plumb, R. A.; Pope, V.

    1990-01-01

    The observation and interpretation of a large, unexpected ozone depletion over Antarctica has changed the international scientific view of stratospheric chemistry. The observations which show the veracity, seasonal nature, and vertical structure of the Antarctic ozone hole are presented. Evidence for Arctic and midlatitude ozone loss is also discussed. The chemical theory for Antarctic ozone depletion centers around the occurrence of polar stratospheric clouds (PSCs) in Antarctic winter and spring; the climatology and radiative properties of these clouds are presented. Lab studies of the physical properties of PSCs and the chemical processes that subsequently influence ozone depletion are discussed. Observations and interpretation of the chemical composition of the Antarctic stratosphere are described. It is shown that the observed, greatly enhanced abundances of chlorine monoxide in the lower stratosphere are sufficient to explain much if not all of the ozone decrease. The dynamic meteorology of both polar regions is given, interannual and interhemispheric variations in dynamical processes are outlined, and their likely roles in ozone loss are discussed.

  7. Polar Terrains

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03577 Polar Terrains

    The region surrounding the South Polar Cap contains many different terrain types. This image shows both etched terrain and a region of 'mounds'.

    Image information: VIS instrument. Latitude 75S, Longitude 286.5E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  8. Modeling the Observed QBO and Inter-Annual Variations of the Diurnal Tide in the Mesosphere

    NASA Technical Reports Server (NTRS)

    Mayr, Hans G.; Mengel, John G.; Huang, F. T.

    2006-01-01

    In the current version of the Numerical Spectral Model (NSM), the Quasi-biennial Oscillation (QBO) is generated primarily by small-scale gravity waves (GW) from Hines' Doppler Spread Parameterization (DSP). The model does not have topography, and the planetary waves are solely generated by instabilities. We discuss a 3D modeling study that describes the QBO extending from the stratosphere into the upper mesosphere, where the oscillation produces significant inter-annual variations in the diurnal tide. The numerical results are compared with temperature measurements from the SABER (TIMED) and MLS (UARS) instruments obtained by Huang et al. (2006). With a GW source that peaks at the Equator and is taken to be isotropic and independent of season, the NSM generates a QBO with variable periods around 26 months and zonal wind amplitudes of almost 25 m/s at 30 km. As reported earlier, the NSM reproduces the observed equinoctial maxima in the diurnal tide at altitudes around 95 km. The modeled QBO modulates the tide such that the seasonal amplitude maxima can vary from one year to another by as much as 30%. To shed light on the underlying mechanisms, the relative importance of the advection terms are discussed, and they are shown to be important in the stratosphere. At altitudes above 80 km, however, the QBO-related inter-annual variations of the tide are generated primarily by GW momentum deposition. In qualitative agreement with the SABER measurements, the model generates distinct zonal-mean QBO temperature variations in the stratosphere and mesosphere. In the stratosphere, the computed amplitudes are not much smaller than those observed, and the rate of downward propagation at the Equator is reproduced. The modeled temperature amplitudes in the mesosphere, however, are much smaller than those observed. The observed and computed temperature variations of the QBO peak at the Equator but extend with phase reversals to high latitudes, in contrast to the zonal winds that are

  9. Multi-Satellite Measurements and Model Predictions of Mesospheric and Upper Stratospheric Influences from the Very Large July 14-16, 2000, Solar Proton Event

    NASA Technical Reports Server (NTRS)

    Jackman, Charles H.; McPeters, Richard D.; Russell, James M.; Bevilacqua, Richard; Labow, Gordon J.; Fleming, Eric L.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    A large solar flare with an associated coronal mass ejection occurred in mid-July and caused a very large solar proton event at the earth in the time period July 14-16, 2000. So far this is the largest solar storm of solar cycle 23. The solar proton fluxes were measured by instruments aboard the GOES-10 satellite and used in our proton energy deposition model to help quantify the energy input to the middle atmosphere during this large solar event. Using this computed energy deposition in the GSFC 2D atmospheric model resulted in a prediction of $>$ 20\\% increases in HO$-(x)$ (H, OH, HO$-(2)$) and $>$ 100\\% increases in NO$-(x)$ (N, NO, NO$-(2)$) constituents in the mesosphere and upper stratosphere at polar latitudes ($>$ 60 degrees geomagnetic). Both the HO$-(x)$ and NO$_fx)$ increases impacted ozone. Large atmospheric impacts have been measured with the NOAA 14 SBUV/2 instrument (0$_(3)$), the UARS HALOE instrument (NO, NO$-(2)$, 0$-(3)$), and the POAM III instrument (0$_{3}$, NO$-(2)$). Preliminary analysis indicates that measured (SBUV/2) and modelled 0$_{3}$ decreases from this solar event are generally in agreement in the Northern Hemisphere. Short-term ozone changes (during the event) indicate $\\sim$ 15% reduction at 2 hPa ($\\sim$ 45 km) up to $\\sim$ 40% reduction at 0.5 hPa ($\\sim$ 55 km). A longer-term ozone depletion of $\\sim$ 5% is indicated between 4 and 2 hPa ($\\sim$ 40-45 km). The middle atmospheric changes caused by this solar event were very large and occurred fairly quickly ($\\sim$ 1-2 days). Such a significant natural perturbation provides a good test of our understanding of the middle atmosphere. The measured and modelled impacts of this solar event will be compared and discussed in this paper.

  10. Evidence from the limb infrared monitor of the stratosphere for nonlocal thermodynamic equilibrium in the nu2 mode of mesospheric water vapour and the nu3 mode of stratospheric nitrogen dioxide

    NASA Technical Reports Server (NTRS)

    Kerridge, Brian J.; Remsberg, Ellis E.

    1989-01-01

    Data from the 6.9-micron H2O channel and the 6.2-micron NO2 channel of the Nimbus 7 Limb Infrared Monitor of the Stratosphere (LIMS) have been used to investigate the daytime enhancement to H2O; the high concentration of H2O sometimes observed in the polar night mesosphere; and the high ratio of daytime to nighttime NO2 in the upper stratosphere. These three phenomena deviate noticeably from the predictions of photochemical theory. The 20 to 30 percent diurnal variation in stratospheric H2O apparent in LIMS data cannot be reconciled with a photochemical lifetime in excess of four months. This is attributed to departure from local thermodynamic equilibrium of daytime emission which had not been accounted for in retrievals. Speculative possibilities of NLTE emission from the H2O nu2 and NO2 nu3 hot bands are discussed. It is found that the nonthermal emission from NO2 significantly affects retrieval of H2O in the polar nighttime and NO2 in the daytime stratosphere at low latitudes.

  11. Residual Circulation in the Stratosphere and Lower Mesosphere as Diagnosed from Microwave Limb Sounder Data.

    NASA Astrophysics Data System (ADS)

    Eluszkiewicz, Janusz; Crisp, David; Zurek, Richard; Elson, Lee; Fishbein, Evan; Froidevaux, Lucien; Waters, Joe; Grainger, R. G.; Lambert, Alyn; Harwood, Robert; Peckham, Gordon

    1996-01-01

    Results for the residual circulation in the stratosphere and lower mesosphere between September 1991 and August 1994 are reported. This circulation is diagnosed by applying an accurate radiative transfer code to temperature, ozone, and water vapor measurements acquired by the Microwave Limb Sounder (MLS) onboard the Upper Atmosphere Research Satellite (UARS), augmented by climatological distributions of methane, nitrous oxide, nitrogen dioxide, surface albedo, and cloud cover. The sensitivity of the computed heating rates to the presence of Mt. Pinatubo aerosols is explored by utilizing aerosol properties derived from the measurements obtained by the Improved Stratospheric and Mesospheric Sounder instrument, also onboard UARS. The computed vertical velocities exhibit a Semiannual oscillation (SAO) around the tropical stratopause, with the region of downward velocities reaching maximum spatial extent in February and August. This behavior reflects the semiannual oscillation in temperature and ozone and mimics that seen in past studies of the October 1978-May 1979 period based on data from the Limb Infrared Monitor of the Stratosphere onboard the Nimbus 7 satellite. The SAO vertical velocities are stronger during the northern winter phase, as expected if planetary waves from the winter hemisphere are involved in driving the SAO. A possible quasi-biennial oscillation (QBO) signal extending from the middle into the upper stratosphere is also hinted at, with the equatorial vertical velocities in the region 10-1 hPa significantly smaller (or even negative) in 1993/94 than in 1992/93. Despite the short data record, the authors believe that this pattern reflects a QBO signal rather than a coincidental interannual variability, since the time-height section of vertical velocity at the equator resembles that of the zonal wind. Wintertime high-latitude descent rates are usually greater in the Northern Hemisphere, but they also exhibit significant variability there. In the three

  12. Mesospheric CO2 ice clouds on Mars observed by Planetary Fourier Spectrometer onboard Mars Express

    NASA Astrophysics Data System (ADS)

    Aoki, Shohei; Giuranna, Marco; Sato, Yuki; Nakagawa, Hiromu; Sato, Takao M.; Wolkenberg, Paulina; Murata, Isao; Kasaba, Yasumasa

    2016-04-01

    We investigate mesospheric CO2 ice clouds on Mars detected by the Planetary Fourier Spectrometer (PFS) onboard Mars Express (MEx). The relatively high spectral resolution of PFS allows firm identification of the clouds' reflection spike. A total of 279 occurrences of the CO2 ice clouds features has been detected at the bottom of 4.3 μm CO2 band from the MEx/PFS data during the period from MY27 to MY32. 115 occurrences out of them are also confirmed by simultaneous observations by MEx/OMEGA imaging spectrometer. The spatial and seasonal distributions of the CO2 ice clouds observed by PFS are consistent with the previous studies: the CO2 ice clouds are only observed between Ls=0° and 140° at distinct longitudinal corridors around the equatorial region (±20°N). The CO2 ice clouds are preferentially detected at local time between 15-17h. The relatively high spectral resolution of PFS allows us to investigate the spectral shape of the CO2 ice clouds features. The CO2 ice clouds reflection spike is peaked between 4.24 and 4.29 μm, with no evidence of the secondary peak at 4.32-4.34 μm observed by MEx/OMEGA (Määttänen et al., 2010). In most of the cases (about 75%), the peak is present between 4.245 and 4.255 μm. Moreover, small secondary peaks are found around 4.28 μm (about 15 occurrences). These spectral features cannot be reproduced by the synthetic spectra with the assumption of a spherical particle shape in our radiative transfer model (DISORT). This can be due to the fact that the available CO2 ice reflective indexes are either inaccurate or inappropriate for the mesospheric temperatures, or that the particle shape is not spherical. Accurate measurements of the reflective index depending on temperature and detailed comparison with the model taking into account non-spherical shapes will give a clue to solve this issue.

  13. Polar Layers

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03581 Polar Layers

    This image shows just one example of the bright and dark markings that appear during summer time. The marks are related to the polar layers. If you happen to see a wild-eyed guy sticking his tongue out at you, you'll know why this image qualifies for the old 'art' category of THEMIS releases.

    Image information: VIS instrument. Latitude 80.6S, Longitude 34.1E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  14. Dynamics of the 4-day wave in the Southern Hemisphere polar stratosphere

    SciTech Connect

    Randel, W.J. ); Lait, L.R. )

    1991-12-01

    Dynamics of the 4-day wave in the Southern Hemisphere polar stratosphere is investigated using horizontal wind and temperature data. These were derived from synoptic maps of satellite-measured brightness temperatures, which were generated using the fast Fourier synoptic mapping technique of Salby. Circulation statistics from these data are compared to those from the National Meteorological Center (NMC) operational stratospheric analyses, demonstrating improvements afforded by detailed treatment of asynoptic sampling effects. The 4-day wave is isolated using temporally filtered data. Several events of wave growth and decay are observed in the upper stratosphere during August 1980. Derived zonal-mean and eddy statistics suggest that the 4-day wave results from an instability of the zonal-mean flow near 55[degrees]-60[degrees]S, at and above 1 mb. Inspection of climatological data suggests the source of the instability to be the [open quotes]double-jet[close quotes] structure in the upper stratosphere and mesosphere (the subtropical mesospheric jet near 30[degrees]S and the high-latitude extension of the polar night jet near 70[degrees]S). Contribution of the 4-day wave to the general circulation of the stratosphere is discussed: one feature attributable to the 4-day wave is a region of positive EP flux divergence in the upper stratosphere near 50[degrees]-60[degrees]S. 22 refs., 12 figs.

  15. Properties of the mesosphere and thermosphere and comparison with CIRA 72

    NASA Astrophysics Data System (ADS)

    Champion, K. S. W.

    Exospheric temperatures of several reference atmosphere are reviewed and a recommendation is made for the exospheric temperature of a proposed mean CIRA. One of the deficiencies of CIRA 72 and other present thermospheric models is the representation of density changes with geomagnetic activity. This deficiency is illustrated with samples of data. The data show the effects of geomagnetic activity, particle precipitation, a solar proton event, and gravity waves. An empirical model developed from the unique AFGL satellite density data bank using multiple linear regression is reviewed. The present model is for low to moderate solar flux and quiet geomagnetic conditions, but it is planned to extend the model to active conditions. Good progress has been made since CIRA 72 was specified in our knowledge and understanding of the properties of the lower thermosphere, although there are still some unresolved problems. The biggest progress has been made in the theory of tidal effects and of particulate energy deposition and of electrojet heating. On the other hand, it is still not possible to define adequately the systematic variations of the lower boundary conditions of thermospheric models. This is due to lack of knowledge of the systematic variations of the structure properties in the 100 to 120 km altitude region and inadequate information on the mesospheric turbulence profile and variations in the turbopause altitude.

  16. Temperature of mesospheric ice retrieved from the O-H stretch band

    NASA Astrophysics Data System (ADS)

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

    2009-08-01

    For the first time, the temperature of mesospheric ice particles is retrieved directly from ice infrared extinction spectra measured in the solar occultation regime. The position of ice O-H stretch band peak varies from 3230cm-1 at T = 120K to 3246cm-1 at T = 155K, which enables the retrieval of ice temperature by fitting a model spectrum to a measured one. The retrieved temperature is independent of cloud vertical and horizontal patchiness and has a random uncertainty of <12K. The retrieval is sensitive to chosen particle shape: cubes, hexagons and spheroids of certain forms give same result. Spheres and rectangular prisms (aspect ratio ≥2) change temperature by 3-4K. For nearly 400 ice spectra analyzed the retrieved temperature for cubes ranges from 120K to 150K with the distribution maximum centered at ˜135K. The standard temperature for same ice spectra retrieved from the gas phase differs considerably and sometimes reaches values of 200K and above.

  17. Non-Migrating Diurnal Tides Generated with Planetary Waves in the Mesosphere

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    We report here the results from a modeling study with our Numerical Spectral Model (NSM) that extends from the ground into thermosphere. The NSM incorporates Hines Doppler Spread Parameterization for small-scale gravity waves (GWs) and describes the major dynamical features of the atmosphere, including the wave driven equatorial oscillations (QBO and SAO), and the seasonal variations of tides and planetary waves. Accounting solely for the solar migrating tidal excitation sources, the NSM generates through dynamical interactions also non-migrating tides in the mesosphere that have amplitudes comparable to those observed. The model produces the diurnal (and semidiurnal) oscillations of the zonal mean (m = 0), and eastward and westward propagating tides for zonal wave numbers m = 1 to 4. To identify the mechanism of excitation for these tides, a numerical experiment is performed. The NSM is run without the heat source for the zonal-mean circulation and temperature variation, and the amplitudes of the resulting nonmigrating tides are then negligibly small. This leads to the conclusion that the planetary waves, which normally are excited in the NSM by instabilities but are suppressed in this case, generate the nonmigrating tides through nonlinear interactions with the migrating tides.

  18. Mesosphere Dynamics with Gravity Wave Forcing. 1; Diurnal and Semi-Diurnal Tides

    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 nonlinear, 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 that is dominated by wave interactions. We discuss diurnal and semi-diurnal tides ill the present paper (Part 1) and planetary waves in the companion paper (Part 2). To provide an understanding of the seasonal variations of tides, in particular with regard to gravity wave processes, numerical experiments are performed that lead to the following conclusions: 1. The large semiannual variations in tile diurnal tide (DT), with peak amplitudes observed around equinox, are produced primarily by GW interactions that involve, in part, planetary waves. 2. The DT, like planetary waves, tends to be amplified by GW momentum deposition, which reduces also the vertical wavelength. 3.Variations in eddy viscosity associated with GW interactions tend to peak in late spring and early fall and call also influence the DT. 4. The semidiurnal semidiurnal tide (SDT), and its phase in particular, is strongly influenced by the mean zonal circulation. 5. The SDT, individually, is amplified by GW's. But the DT filters out GW's such that the wave interaction effectively reduces the amplitude of the SDT, effectively producing a strong nonlinear interaction between the DT and SDT. 6.) Planetary waves generated internally by baroclinic instability and GW interaction produce large amplitude modulations of the DT and SDT.

  19. QBO Generated Inter-annual Variations of the Diurnal Tide in the Mesosphere

    NASA Technical Reports Server (NTRS)

    Mayr, Hans G.; Mengel, John G.

    2004-01-01

    We report results from a study with the Numerical Spectral Model (NSM), which produces in the mesosphere significant inter-annual variations in the diurnal tide. Applying Hines Doppler Spread Parameterization (DPS), small-scale gravity waves (GW) drive the Quasi-biennial Oscillation (QBO) and Semi-annual Oscillation (SAO). With a GW source that peaks at the equator and is taken to be isotropic and independent of season, the NSM generates near the equator a QBO with variable periods around 27 months and zonal wind amplitudes close to 20 m / s at 30 Ism. As reported earlier, the NSM reproduces the observed equinoctial maxima in the diurnal tide at altitudes around 95 km. In the present paper it is shown that the QBO modulates the tide such that the seasonal amplitude maxima can vary from one year to another by as much as 30%. Since the period of the QBO is variable, its phase relative to the seasonal cycle changes. The magnitude of the QBO modulation of the tide thus varies considerably as our long-term model simulation shows. To shed light on the underlying mechanism, the relative importance of the linearized advection terms are discussed that involve the meridional and vertical winds of the diurnal tide.

  20. Winds and temperatures in the stratosphere and mesosphere at ALOMAR derived by Doppler lidar

    NASA Astrophysics Data System (ADS)

    Hildebrand, Jens; Baumgarten, Gerd; Fiedler, Jens; Lübken, Franz-Josef

    2016-04-01

    Wind and temperature measurements in the middle atmosphere are crucial for a comprehensive understanding of atmospheric dynamics. Unfortunately, they are very challenging, especially with vertical and temporal resolutions reasonable for gravity-wave studies. The Doppler Rayleigh Iodine Spectrometer (DoRIS) of the Rayleigh/Mie/Raman lidar at the Arctic station ALOMAR in Northern Norway (69°N, 16°E) is the only remote sensing instrument that simultaneously derives temperatures and two wind components in the entire stratosphere and mesosphere, even under daylight conditions, necessarily for long-duration gravity-wave studies. The temporal and vertical resolutions are, typically, 1 h and 3 km, respectively. We are going to present case studies of middle atmospheric winds and temperatures, obtained during winter seasons 2010 - 2015. During a sounding rocket campaign in March 2015 an extensive salvo of meteorological rockets for in-situ wind measurements was launched at the Andøya Space Center close to ALOMAR. This gave the opportunity for a comprehensive comparison of winds derived by lidar and in-situ observations in the middle atmosphere, whose results we will present.

  1. Photochemical response of the nighttime mesosphere to electric field heating—Onset of electron density enhancements

    NASA Astrophysics Data System (ADS)

    Kotovsky, D. A.; Moore, R. C.

    2016-05-01

    Onsets of electron density enhancements in the upper nighttime mesosphere produced by electric field heating of electrons are examined using a photochemical model that accounts for 29 dynamic species via a set of 156 reactions. Physical mechanisms are identified which result in electron density enhancements that continuously increase for up to several seconds after electric field heating, establishing the conditions under which early VLF scattering is either "fast" (<20 ms) or slower (>20 ms, including "slow," ≥500 ms). During heating, O- ions are produced by heterolysis, e- + O2 → e- + O- + O+, and dissociative attachment, e-+ O2 → O- + O. Following heating, a significant proportion of O- ions associatively detach with molecular oxygen, O- + O2 → O3 + e-, and atomic oxygen, O- + O → O2 + e-. If enough O- ions are produced during heating such that O- detachment exceeds electron loss (predominantly attachment, e- + O3 → O2- + O, and/or electron-ion recombination), electron densities will continue to increase after heating has ended. Consequently, the total risetime of electron density enhancements produced by electric field heating is controlled by the duration of the electric field heating and (in some cases) the effects of O- detachment following heating.

  2. Variability in the Mesosphere/Thermosphere/Ionosphere System During the Quiet Time of April 2002

    NASA Astrophysics Data System (ADS)

    Goncharenko, L. P.; Salah, J.; Coster, A.; Rideout, W.; Zhang, S. R.; Paxton, L.; Zhang, Y.; Crowley, G.; Taran, V.; Reinisch, B.; Clark, R.; Manson, A.; Mitchell, N.; Murayama, Y.; Riggin, D.; Singer, W.

    2003-12-01

    We investigate the structure of the global mesosphere-thermosphere-ionosphere system using multi-instrument observations during the April 2002 period, with focus on geomagnetically quiet periods. Large variations in electron density were observed at midlatitudes by the array of incoherent scatter radars, ionosondes and GPS receivers. On April 16, 2002, electron density decreases to ~50-70% of the level observed on Apr 15, 2002. This depletion far exceeds commonly observed 10-20% quiet-time variations. At the same time, the observations from the array of MF and meteor radars show global presence of planetary wave disturbances, and a westward offset in the zonal wind of 15 m/s was noticed at locations coincident with the area of large variations in the electron density. We find that variations in ionospheric parameters have a strong relationship with neutral density, and show that an extensive area of depleted electron density as observed by GPS receivers, ISR radars and ionosondes is coincident with the area of large decrease in the column integrated O/N2 ratio measured by the GUVI instrument on board of TIMED satellite. Similar variations are also predicted by the TIMEGCM/ASPEN model in both O/N2 ratio and electron density, though the magnitude of the variations in the model is significantly smaller.

  3. Radar observations of the diurnal tide in the tropical mesosphere-lower thermosphere region: Longitudinal variabilities

    NASA Astrophysics Data System (ADS)

    Gurubaran, S.; Rajaram, R.; Nakamura, T.; Tsuda, T.; Riggin, D.; Vincent, R. A.

    2009-04-01

    Significant attention is being paid in recent times by several observational and modeling studies to quantify the spatial and temporal variabilities of diurnal tide in the mesosphere and lower thermosphere (MLT) region. These variabilities are ascribed to spatial and temporal variations in the tidal forcing or interactions between the propagating tides and background wind, planetary waves or gravity waves. The present work makes use of simultaneous ground-based radar wind observations of different durations from five equatorial/low latitude sites in the Indian, Indonesian and Pacific sectors: Tirunelveli (8.7°N, 77.8°E), Jakarta (6.4°S, 106.7°E), Pontianak (0.03°N, 109°E), Kauai (22°N, 160°W) and Christmas Island (2°N, 157°W). This study delineates the longitudinal differences in the tidal characteristics in (i) interannual time scales over Tirunelveli and Kauai during 1993-2002, (ii) seasonal time scales over Christmas Island, Jakarta and Tirunelveli for the years 1993-1997 and (iii) shorter than seasonal time scales over Christmas Island, Pontianak and Tirunelveli during 1996-1997. An important observational feature noticed in this work is the differing behavior of the long-term tidal fields over Tirunelveli and Kauai. The monthly tidal amplitudes over Tirunelveli reveal a strong QBO signature whereas a similar, strong QBO signal could not be traced in the long-term observations from Kauai.

  4. Simultaneous observations of a Mesospheric Inversion Layer and turbulence during the ECOMA-2010 rocket campaign

    NASA Astrophysics Data System (ADS)

    Szewczyk, A.; Strelnikov, B.; Rapp, M.; Strelnikova, I.; Baumgarten, G.; Kaifler, N.; Dunker, T.; Hoppe, U.-P.

    2013-05-01

    From 19 November to 19 December 2010 the fourth and final ECOMA rocket campaign was conducted at Andøya Rocket Range (69° N, 16° E) in northern Norway. We present and discuss measurement results obtained during the last rocket launch labelled ECOMA09 when simultaneous and true common volume in situ measurements of temperature and turbulence supported by ground-based lidar observations reveal two Mesospheric Inversion Layers (MIL) at heights between 71 and 73 km and between 86 and 89 km. Strong turbulence was measured in the region of the upper inversion layer, with the turbulent energy dissipation rates maximising at 2 W kg-1. This upper MIL was observed by the ALOMAR Weber Na lidar over the period of several hours. The spatial extension of this MIL as observed by the MLS instrument onboard AURA satellite was found to be more than two thousand kilometres. Our analysis suggests that both observed MILs could possibly have been produced by neutral air turbulence.

  5. Simultaneous rocket and MST radar observation of an internal gravity wave breaking in the mesosphere

    NASA Technical Reports Server (NTRS)

    Smith, S. A.; Fritts, D. C.; Balsley, B. B.; Philbrick, C. R.

    1986-01-01

    In June, 1983, the Structure and Atmospheric Turbulence Environment (STATE) rocket and Poker Flat Mesophere-Stratosphere-Troposphere radar campaign was conducted to measure the interaction between turbulence, electron density and electron density gradient that has produced unusually strong MST radar echoes from the summer mesosphere over Poker Flat, Alaska. Analysis or radar wind measurements and a concurrent wind and temperature profile obtained from a rocket probe carrying a three-axis accelerometer are given. The two data sets provide a fairly complete (and in some cases, redundant) picture of the breaking (or more correctly, the saturation) of a large-amplitude, low-frequency, long-wavelength internal gravity wave. The data show that small-scale turbulence and small-scale wave intensity is greatest at those altitudes where the large-scale wave-induced temperature lapse rate is most negative or most nearly unstable, but the wind shear due to the large-scale wave is a minimum. A brief review of linear gravity-wave theory is presented as an aid to the identification of the gravity-wave signature in the radar and rocket data. Analysis of the time and height cross sections of wind speed and turbulence intensity observed by the Poker Flat MST radar follows. Then, the vertical profile of temperature and winds measured by a rocket probe examined. Finally, the use of the independent data sets provided by the rocket and the radar are discussed and implications for theories of wave saturation are presented.

  6. The Interpretation of Sage II Ozone Measurements in the Lower Mesosphere.

    NASA Astrophysics Data System (ADS)

    Chu, Ding-Chong Allen

    SAGE II observations of ozone at sunrise and sunset (solar zenith angle = 90^circ) at approximately the same tropical latitude and on the same day exhibit larger concentrations at sunrise than at sunset between 55 km and 65 km altitude. Because of rapid conversion of atomic oxygen to ozone at sunset and the reverse at sunrise, the onion peeling assumption of constant ozone in the SAGE II retrievals is invalid in this altitude range. The observations are compared against predictions from a one-dimensional model by deriving simulated ozone profiles obtained by applying the onion peel procedure to model results. Good agreement between the observed and modeled sunrise/sunset ratios is then obtained. The results indicate that the SAGE II ozone retrievals overestimate by a factor of 1.3 at sunrise and 1.1 at sunset at 65 km (for example). Between 55 and 60 km altitude the Chapman reactions produce an adequate simulation of the sunrise and sunset ratio, but between 60 and 65 km this ratio is affected by the destruction of O_{ rm x} by HO_{rm x} during the first part of the night. SAGE II ozone profiles between 60 and 65 km altitude thus provide information on mesospheric HO_{rm x} chemistry not only through profiles averages but also through the sunrise/sunset ratio. The observations, for example, indicate an OH concentration at 65 km altitude in the tropics an hour after dark of approximately 8 times 10^6 cm ^{-3}.

  7. Short-Term Tidal Variability in the Mesosphere/Lower Thermosphere from SABER

    NASA Astrophysics Data System (ADS)

    Oberheide, J.; Pedatella, N. M.; Du, J.; Lieberman, R. S.; Siskind, D. E.

    2015-12-01

    The understanding of migrating and nonmigrating tidal propagation from the troposphere and stratosphere into the mesosphere/lower thermosphere and upper thermosphere has much improved over the past few years. Yet, space-borne diagnostics of tides from single satellites like TIMED are limited to > monthly mean averages because of the slow orbit precession and the resulting local solar time coverage. Ground-based observations and whole atmosphere models on the other hand strongly suggest a short-term tidal variability on the order of a factor of two within a few days. This paper attempts to address this challenge by presenting a different approach than the conventional wavenumber/frequency Fourier fits to the satellite data: tides are diagnosed from the vertical/longitudinal structure of ascending-descending orbit node differences. This so-called "tidal deconvolution" method is applied to SABER temperature observations over one solar cycle. The resulting diurnal amplitudes and phases have an effective time resolution of approximately one week and are compared to short-term tidal diagnostics based on Fourier fits to multiple satellites and results from the NOGAPS-ALPHA, WACCM and eCMAM30 models for various tidal components. Preliminary results suggest that tidal components forced by tropical convection respond strongly to convective precipitation changes associated with the Madden-Julian-Oscillation while other nonmigrating tides show clear signatures of wave-wave interaction.

  8. Annual variation in temperature and composition of the thermosphere and upper mesosphere

    NASA Technical Reports Server (NTRS)

    Mayr, H. G.; Harris, I.

    1977-01-01

    A three-dimensional circulation model, including UV (O2 dissociation) and EUV sources, is used to study the wind field and the effects of temperature and composition on annual thermospheric variations. The results are compared to those of OGO-6 and AE-C. Within an 800-1200 K temperature range, summer to winter temperature variation is studied as a function of solar activity. It is found that the model correctly predicts H, He, O, N2, O2, and Ar measurements. It is suggested that a small winter maximum in mesospheric temperature is caused by large-scale circulation induced by EUV heating. This effect, however, is masked by the energy released in O2 dissociation. The annual temperature amplitude and the winter oxygen bulge are noted to increase with increasing solar activity, whereas the winter helium bulge is noted to decrease with enhanced exospheric return flow. It is felt that the dependence of the F2 region winter anomaly on solar activity may be significantly affected by the solar activity effect in atomic oxygen.

  9. Equatorial X-rays and their effect on the lower mesosphere

    NASA Technical Reports Server (NTRS)

    Goldberg, R. A.; Jones, W. H.; Williamson, P. R.; Barcus, J. R.; Hale, L. C.

    1976-01-01

    On the night of May 23/24, 1975, a sequence of rocket and balloon experiments was launched from Chilca Base, Peru (12.5 deg S, 76.8 deg W, magnetic dip = - 0.7 deg). Detailed analysis and comparisons of the data yielded the first direct measurement of lower mesospheric response to a galactic X-ray source. This result could only have been determined at the equator, where cosmic ray background effects are minimal. The objective of the experiments was to seek out the equatorial energetic electron belt, sporadically reported to contain fluxes near auroral levels, measure the bremsstrahlung radiation produced by this particle belt, and determine the influence of this radiation on the middle atmosphere. High altitude rocket payloads (Nike Tomahawk 18.170 and 18.171) were launched to probe the thermosphere during and following the anticipated downward drift period. Each carried an on-axis X-ray scintillation detector and Geiger Mueller energetic electron detectors. Magnetometers and lunar sensors were used to determine payload aspect.

  10. Overturning instability in the mesosphere and lower thermosphere: analysis of instability conditions in lidar data

    NASA Astrophysics Data System (ADS)

    Hurd, L.; Larsen, M. F.; Liu, A. Z.

    2009-07-01

    Resonant sodium lidar measurements from the transition region between the mesosphere and lower thermosphere have revealed frequently-occurring overturning events characterized by vertical scales of ~3-6 km and timescales of several hours. Larsen et al. (2004) proposed that a convective roll instability, similar to that found in the planetary boundary layer, is the likely mechanism responsible for the events. This type of instability requires an inflection point in the background winds near the center of the vortex roll with a low static stability region capped by an inversion. The earlier paper argued that the conditions required to support the instability are common in the altitude range where the features are found. In this paper, we use data from the University of Illinois sodium lidar that was located at the Starfire Optical Range near Albuquerque, New Mexico, and from the Maui/MALT Lidar Facility in Hawaii and present several cases that are used to examine the behavior of the inflection point in detail as a function of time during the evolution of the overturning event. In addition, we examine the background static stability conditions using the temperature data from the lidar.

  11. Improved short-term variability in the thermosphere-ionosphere-mesosphere-electrodynamics general circulation model

    NASA Astrophysics Data System (ADS)

    Häusler, K.; Hagan, M. E.; Baumgaertner, A. J. G.; Maute, A.; Lu, G.; Doornbos, E.; Bruinsma, S.; Forbes, J. M.; Gasperini, F.

    2014-08-01

    We report on a new source of tidal variability in the National Center for Atmospheric Research thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (TIME-GCM). Lower boundary forcing of the TIME-GCM for a simulation of November-December 2009 based on 3-hourly Modern-Era Retrospective Analysis for Research and Application (MERRA) reanalysis data includes day-to-day variations in both diurnal and semidiurnal tides of tropospheric origin. Comparison with TIME-GCM results from a heretofore standard simulation that includes climatological tropospheric tides from the global-scale wave model reveal evidence of the impacts of MERRA forcing throughout the model domain, including measurable tidal variability in the TIME-GCM upper thermosphere. Additional comparisons with measurements made by the Gravity field and steady-state Ocean Circulation Explorer satellite show improved TIME-GCM capability to capture day-to-day variations in thermospheric density for the November-December 2009 period with the new MERRA lower boundary forcing.

  12. Mesospheric H2O Concentrations Retrieved from SABER/TIMED Measurements

    NASA Technical Reports Server (NTRS)

    Feofilov, A. G.; Marshall, B. T.; Garcia-Comas, M.; Kutepov, A. A.; Lopez-Puertas, M.; Manuilova, R. O.; Yankovsky, V.A.; Goldberg, R. A.; Gordley, L. L.; Petelin, S.; Russell, J. M., III

    2008-01-01

    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 populations of H2O(v2) vibrational levels are in non-Local Thermodynamic Equilibrium (non-LTE) above approximately 55 km altitude and the interpretation of 6.3 micron radiance requires utilizing non-LTE H2O model that includes various energy exchange processes in the system of H2O vibrational levels coupled with O2, N2, and CO2 vibrational levels. We incorporated these processes including kinetics of O2/O3 photolysis products to our research non-LTE H2O model and applied it for the development and optimization of SABER operational model. The latter has been validated using simultaneous SCISAT1/ACE occultation measurements. This helped us to estimate CO2(020)-O2(X,v=I), O2(X,v=I)- H2O(010), and O2(X,v=1) O rates at mesopause temperatures that is critical for an adequate interpretation of non-LTE H2O radiances in the MLT. The first distributions of seasonal and meridional H2O concentrations retrieved from SABER 6.3 micron radiances applying an updated non-LTE H2O model are demonstrated and discussed.

  13. Nimbus-7 Stratospheric and Mesospheric Sounder (SAMS) experiment data user's guide

    NASA Technical Reports Server (NTRS)

    Taylor, F. W.; Rodgers, C. D.; Nutter, S. T.; Oslik, N.

    1989-01-01

    The Stratospheric and Mesospheric Sounder (SAMS) aboard Nimbus-7 observes infrared radiation from the atmospheric limb. Global upper atmosphere temperature profiles and vertical concentrations of H2O, NO, N2O, CH4 and CO2 are derived from these measurements. The status of all channels was carefully monitored. Temperature and composition were retrieved from the measurements by linearizing the direct equation about an a priori profile and using an optimum statistical estimator to find the most likely solution. The derived temperature and composition profiles are archived on two tape products whose file structure and record formats are described in detail. The gridded retrieved temperature tape (GRID-T) contains daily day and night average temperatures at 62 pressure levels in a 2.5 degree latitude by 10 degree longitude grid extending from 67.5 degrees N to 50 degrees S. The zonal mean methane and nitrous oxide composition tape (ZMT-G) contains zonal mean day and night average CH4 and N2O mixing ratios at 31 pressure levels for 2.5 degrees latitude zones extending from 67.5 degrees N to 50 degrees S.

  14. A Rocket Investigation of Mesospheric Eddy Diffusion Effects on Airglow and Oxygen Chemistry

    NASA Technical Reports Server (NTRS)

    Ulwick, James C.

    2001-01-01

    A Terrier Orion rocket was launched at 0750 Z on 02/25/98 about seven minutes after the Clemson University chemical release rocket. Measurements made of the electron density by a dc probe calibrated by a capacitance probe showed several layers of electron density on a rocket ascent in the altitude range from 90 to 110 km. Rocket descent results showed several but not all of the ascent structure. From power spectral analysis of the measured electron densities, turbulent parameters are derived Measurements were made on rocket ascent and descent by an infrared radiometer of the OH Meinel (3-1) band and O2 singlet delta emissions. Profiles of the emissions are presented and discussed on both rocket ascent and descent an enhancement of the OH emission monitored by the OH radiometer was observed above 90 km. The glow was not defected by the O2 radiometer and was significantly reduced on rocket descent. Using these data and a mechanistic analysis, a profile proportional to atomic oxygen is obtained. This profile is compared to one from the ATOX probe on the rocket. A one-dimensional (1-D) photochemical model that solves the time-dependent continuity equations is used with the rocket data to investigate the odd-oxygen concentration in the near equatorial mesosphere.

  15. An investigation of turbulent scatter from the mesosphere as observed by coherent-scatter radar

    NASA Technical Reports Server (NTRS)

    Gibbs, K. P.; Bowhill, S. A.

    1983-01-01

    Turbulent scatter from he mesosphere is observed using the Urbana coherent-scatter radar. The variation in signal-to-noise ratio as a function of time-of-day is examined. The origin of scattering regions is investigated by comparing the variations in scattered power and Doppler velocity. Nighttime echoes are shown for periods of enhanced electron concentration. The spectrum of the returned signal is studied with a resolution of ten seconds. Spectral information is used to increase altitude resolution and observe the motion of scatterers. The expected variation in signal-to-noise ratio with solar flux is observed. It is found that variations in the scattered power generally do not correspond to the gravity waves which are simultaneously observed. Turbulent layers are observed at altitudes with high shear in the horizontal velocity and at altitudes with low shear. The ten-second resolution is necessary to distinguish meteor echoes from echoes produced by the advection of a scattering layer through the radar beam.

  16. Global Ultraviolet Imager (GUVI) for the NASA Thermosphere-Ionsphere-Mesosphere Energetics and Dynamics (TIMED) mission

    NASA Astrophysics Data System (ADS)

    Christensen, Andrew B.; Walterscheid, Richard L.; Ross, Martin N.; Meng, Ching-I.; Paxton, Larry J.; Anderson, Donald E.; Crowley, Geoffrey; Avery, Susan K.; Craven, John D.; Meier, Robert R.; Strickland, Douglas J.

    1994-09-01

    The global ultraviolet imager (GUVI) investigation is designed to provide quantitative observations and interpretation of the Earth's airglow and auroral emissions in support of the NASA thermosphere, ionosphere, mesosphere, energy and dynamics (TIMED) mission. It addresses TIMED objectives dealing with energetics, dynamics, and the specification of state variables. The instrument provides multiple-wavelength, simultaneous `monochromatic' images of the far-ultraviolet emission (115 to 180 nm) using a scan mirror to sweep the instantaneous field of view of a spectrographic imager through an arc of up to 140 degree(s) aligned perpendicular to the orbit plane of the spacecraft. The instantaneous field of view is 11.8 degree(s) by 0.37 degree(s) (adjustable) along the slit and perpendicular to the slit, respectively. The field of view is mapped to a two-dimensional image plane with up to 64 spatial pixels by 160 spectral pixels of spectral width 0.4 nm per pixel. Binning of pixels can be performed along both the spatial and spectral axes of the array to reduce the demands on the downlink telemetry. The f/3 Rowland circle scanning spectrographic imager is outfitted with a toroidal grating ruled at 1200 grooves per millimeter. The fore-optics consists of a plane scanning mirror and an off-axis parabolic telescope. The detector is a photon-counting microchannel plate with a wedge and strip anode mounted in a sealed tube.

  17. ROCKETMAS: A sounding-rocket-based remote sensing measurement of mesospheric water vapor and ozone

    NASA Technical Reports Server (NTRS)

    Croskey, C. L.; Olivero, J. J.; Puliafito, S. E.; Mitchell, J. D.

    1994-01-01

    The ROCKETMAS rocketborne technique, based on the shuttle-borne millimeter wave atmospheric sounder (MAS), to obtain water vapor and ozone measurements with vertical resolution, is described. The concentrations of mesospheric water vapor and ozone are not well known, yet both contribute significantly to the chemical and radiative structure of that region. In situ measurements of water vapor are difficult to make because water that was absorbed on the instrument surfaces outgasses in space and contaminates the local environment of the payload. However, a remote sensing technique that uses a long pathlength through the atmosphere greatly reduces the effect of such local contamination. The 183.3 GHz line of water vapor and 184.4 GHz line of ozone are good choices for spaceborne radiometer measurements because one front-end mixer assembly can be used to simultaneously observe both gases. The design of a sounding rocket based millimeter wave radiometer for measuring water vapor and ozone with a height resolution not possible by either ground based or limb sounding techniques is described.

  18. On the Origin of Polar Vortex Air

    NASA Technical Reports Server (NTRS)

    Rosenfield, J. E.; Schoeberl, M. R.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    The existence of the multi-year HALOE CH4 data set, together with some comparisons of forward with back trajectory calculations which we have carried out, has motivated us to reexamine the question of polar vortex descent. Three-dimensional diabatic trajectory calculations have been carried out for the seven month fall to spring period in both the northern hemisphere (NH) and southern hemisphere (SH) polar stratosphere for the years 1992-1999. These computations are compared to fixed descent computations where the parcels were fixed at their latitude-longitude locations and allowed to descend without circulating. The forward trajectory computed descent is always less than the fixed descent due to horizontal parcel motions and variations in heating rates with latitude and longitude. Although the forward calculations estimate the maximum amount of descent that can occur, they do not necessarily indicate the actual origin of springtime vortex air. This is because more equator-ward air can be entrained within the vortex during its formation. To examine the origin of the springtime vortex air, the trajectory model was run backward for seven months from spring to fall. The back trajectories show a complex distribution of parcels in which one population originates in the upper stratosphere and mesosphere and experiences considerable descent in the polar regions, while the remaining parcels originate at lower altitudes of the middle and lower stratosphere and are mixed into the polar regions during vortex formation without experiencing as much vertical transport. The amount of descent experienced by the first population shows little variability from year to year, while the computed descent and mixing of the remaining parcels show considerable interannual variability due to the varying polar meteorology. Because of this complex parcel distribution it is not meaningful to speak of a net amount of descent experienced over the entire winter period. Since the back trajectories

  19. Long-term Trends in Mesospheric Temperatures at high and low latitudes derived from OH airglow spectra of Kiruna FTS and Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Kim, Yongha; Kim, Jeong-Han; Kim, Gawon; Lee, Youngsun

    2016-07-01

    We have analyzed mesospheric temperatures from OH airglow measurements with Fourier Transform Spectrometer (FTS) in the period of 2003 - 2012 at Kiruna (67.9°N, 21.1°E). We also derived mesospheric temperatures from rotational emission lines of the OH airglow (8-3) band in the sky spectra of Sloan Digital Sky Survey (SDSS) in the period of 2000 - 2014. The main objective of SDSS is to make a detailed 3-dimensional map of the universe by observing images and spectra of various celestial objects at Apache Point Observatory (APO, 32°N 105°W). From both temperature sets we first estimated the solar responses of mesospheric temperatures to F10.7 variation and the seasonal variation of mesospheric temperatures. After removing the solar response, we found the long-term mesospheric temperature trends of -4 ˜-6.6 K/decade at Kiruna and -0.02 ± 0.7 K/decade at Apache Point. Our results indicate significant cooling trend at the high latitude but very little or no cooling at the low latitude. Although both trends are comparable and consistent with other studies, the temperature trend from SDSS spectra should be regarded as unique contribution to global monitoring of climate change because the SDSS project is completely independent of climate studies.

  20. Dynamics of the Polar Disk Galaxy NGC 4650A

    NASA Astrophysics Data System (ADS)

    Napolitano, N. R.; Iodice, E.; Arnaboldi, M.

    2014-05-01

    We present the dark matter distribution around the polar disk galaxy NGC 4650A. We use extended H I data along the polar disk and long slit kinematics along the spheroid and constrain the dark matter halo scales along the two directions under equilibrium assumptions and a Navarro-Frank-White profile. The different scale lengths along the two axes show that the the dark halo has an axis ratio c/a≃0.5 in agreement with expectations from cosmological simulations.

  1. Dark Matters

    ScienceCinema

    Joseph Silk

    2016-07-12

    One of the greatest mysteries in the cosmos is that it is mostly dark.  Astronomers and particle physicists today are seeking to unravel the nature of this mysterious, but pervasive dark matter which has profoundly influenced the formation of structure in the universe.  I will describe the complex interplay between galaxy formation and dark matter detectability and review recent attempts to measure particle dark matter by direct and indirect means.

  2. Dark Matters

    SciTech Connect

    Joseph Silk

    2009-09-23

    One of the greatest mysteries in the cosmos is that it is mostly dark.  Astronomers and particle physicists today are seeking to unravel the nature of this mysterious, but pervasive dark matter which has profoundly influenced the formation of structure in the universe.  I will describe the complex interplay between galaxy formation and dark matter detectability and review recent attempts to measure particle dark matter by direct and indirect means.

  3. Dark matters

    NASA Astrophysics Data System (ADS)

    Steigman, Gary

    The observational evidence for dark matter in the universe is reviewed. Constraints on the baryon density from primordial nucleosynthesis are presented and compared to the dynamical estimates of the mass on various scales. Baryons can account for the observed luminous mass as well as some, perhaps most, of the 'observed' dark mass. However if, as inflation/naturalness suggest, the total density of the universe is equal to the critical density, then nonbaryonic dark matter is required. The assets and liabilities of, as well as the candidates for, hot and cold dark matter are outlined. At present, there is no completely satisfactory candidate for nonbaryonic dark matter.

  4. Polarized internal target apparatus

    DOEpatents

    Holt, Roy J.

    1986-01-01

    A polarized internal target apparatus with a polarized gas target of improved polarization and density achieved by mixing target gas atoms with a small amount of alkali metal gas atoms, and passing a high intensity polarized light source into the mixture to cause the alkali metal gas atoms to become polarized which interact in spin exchange collisions with target gas atoms yielding polarized target gas atoms.

  5. Polarized internal target apparatus

    DOEpatents

    Holt, R.J.

    1984-10-10

    A polarized internal target apparatus with a polarized gas target of improved polarization and density (achieved by mixing target gas atoms with a small amount of alkali metal gas atoms, and passing a high intensity polarized light source into the mixture to cause the alkali metal gas atoms to become polarized which interact in spin exchange collisions with target gas atoms yielding polarized target gas atoms) is described.

  6. Investigation of in-plane- and z-polarized intersubband transitions in pyramid-shaped InAs/GaAs quantum dots coupled to wetting layer: Size and shape matter

    SciTech Connect

    Sabaeian, Mohammad Shahzadeh, Mohammadreza

    2014-07-28

    In this work, the effects of the shape and size on the intersubband electronic and optical properties of three-dimensional self-assembled pyramid-shaped InAs/GaAs quantum dots (QDs) were investigated in detail. More precisely, in-plane- and z-polarized transitions dipole moment (TDM), oscillator strength (OS), and absorption coefficients of P-to-S, WL-to-P, and WL-to-S transitions were studied as a function of the QD height. The P-to-S TDM showed to be strong and purely in-plane-polarized transition dominating two others. However, the TDMs and OSs of WL-to-P and WL-to-S transitions which are in-plane- and z-polarized transitions, respectively, showed a competition behavior for short and tall QDs. The former dominates for short QDs, and the latter for tall QDs. The physical reasons behind these interesting phenomena were also explained using the probability of finding the carriers in the pyramid region attached to the WL. The theoretical results are in good agreement with experimental data reported for short QDs [Appl. Phys. Lett. 82, 630 (2003)].

  7. Optical polarizing neutron devices designed for pulsed neutron sources

    SciTech Connect

    Takeda, M.; Kurahashi, K.; Endoh, Y.; Itoh, S.

    1997-09-01

    We have designed two polarizing neutron devices for pulsed cold neutrons. The devices have been tested at the pulsed neutron source at the Booster Synchrotron Utilization Facility of the National Laboratory for High Energy Physics. These two devices proved to have a practical use for experiments to investigate condensed matter physics using pulsed cold polarized neutrons.

  8. Lorentz and CPT Tests with Spin-Polarized Solids

    SciTech Connect

    Bluhm, Robert; Kostelecky, V. Alan

    2000-02-14

    Experiments using macroscopic samples of spin-polarized matter offer exceptional sensitivity to Lorentz and CPT violation in the electron sector. Data from existing experiments with a spin-polarized torsion pendulum provide sensitivity in this sector rivaling that of all other existing experiments and could reveal spontaneous violation of Lorentz symmetry at the Planck scale. (c) 2000 The American Physical Society.

  9. Primordial features and Planck polarization

    NASA Astrophysics Data System (ADS)

    Hazra, Dhiraj Kumar; Shafieloo, Arman; Smoot, George F.; Starobinsky, Alexei A.

    2016-09-01

    With the Planck 2015 Cosmic Microwave Background (CMB) temperature and polarization data, we search for possible features in the primordial power spectrum (PPS). We revisit the Wiggly Whipped Inflation (WWI) framework and demonstrate how generation of some particular primordial features can improve the fit to Planck data. WWI potential allows the scalar field to transit from a steeper potential to a nearly flat potential through a discontinuity either in potential or in its derivatives. WWI offers the inflaton potential parametrizations that generate a wide variety of features in the primordial power spectra incorporating most of the localized and non-local inflationary features that are obtained upon reconstruction from temperature and polarization angular power spectrum. At the same time, in a single framework it allows us to have a background parameter estimation with a nearly free-form primordial spectrum. Using Planck 2015 data, we constrain the primordial features in the context of Wiggly Whipped Inflation and present the features that are supported both by temperature and polarization. WWI model provides more than 13 improvement in χ2 fit to the data with respect to the best fit power law model considering combined temperature and polarization data from Planck and B-mode polarization data from BICEP and Planck dust map. We use 2-4 extra parameters in the WWI model compared to the featureless strict slow roll inflaton potential. We find that the differences between the temperature and polarization data in constraining background cosmological parameters such as baryon density, cold dark matter density are reduced to a good extent if we use primordial power spectra from WWI. We also discuss the extent of bispectra obtained from the best potentials in arbitrary triangular configurations using the BI-spectra and Non-Gaussianity Operator (BINGO).

  10. Effect of cyclone Nilofar on mesospheric wave dynamics as inferred from optical nightglow observations from Mount Abu, India

    NASA Astrophysics Data System (ADS)

    Singh, Ravindra P.; Pallamraju, Duggirala

    2016-06-01

    Mesospheric nightglow intensities at three emissions (O2(0-1), OH(6-2) bands, and Na(589.3 nm)) from a low-latitude location, Gurushikhar, Mount Abu (24.6°N, 72.8°E), in India, showed similar wave features on 26 October 2014 with a common periodicity of around 4 h. A convective activity due to the cyclone Nilofar, which had developed in the Arabian Sea during 25-31 October 2014, was found to be the source as this too showed a gravity wave period coherent with that of the mesospheric emissions on the 26th. The periodicities at the source region were obtained using outgoing longwave radiation fluxes (derived from Kalpana-1 satellite) which were used as a tracer of tropospheric activity. Cyclone Nilofar had two centers located at a distance of 1103 and 1665 km from the observational station. From the phase offset in time between residuals of O2 and OH emission intensities and the observed common periodicity the vertical phase speed and wavelength have been found to be 1.13 ms-1 and 16.47 km. From the wavelet analyses it is seen that the travel time of the wave from the convection region to O2 emission height was around 8.1 h. From these observations the horizontal phase speed and wavelength of the wave in the mesosphere were calculated to be 37.8 ms-1 and 553 km. These results thus provide not only unambiguous evidence on the vertical coupling of atmospheres engendered by the tropical cyclone Nilofar but also the characteristics of waves that exist during such cyclonic events.

  11. Space-time integrity of improved stratospheric and mesospheric sounder and microwave limb sounder temperature fields at Kelvin wave scales

    NASA Astrophysics Data System (ADS)

    Stone, E. M.; Stanford, J. L.; Ziemke, J. R.; Allen, D. R.; Taylor, F. W.; Rodgers, C. D.; Lawrence, B. N.; Fishbein, E. F.; Elson, L. S.; Waters, J. W.

    1995-07-01

    Space-time analyses, which are sensitive to details of retrieval and gridding processes not seen in zonal and time means, are used to investigate the integrity of version 8 gridded retrieved temperatures from the improved stratospheric and mesospheric sounder (ISAMS) on the upper atmosphere research satellite (UARS). This note presents results of such analyses applied to ISAMS tropical data. Comparisons are made with microwave limb sounder (MLS), also on UARS, temperatures. Prominent zonal wave number 1 features are observed with characteristics similar to those expected for Kelvin waves. Time versus longitude plots reveal quasi-regular eastward phase progression from November 1991 to mid-January 1992. The perturbations extend throughout the upper stratosphere and lower mesosphere (altitudes of 32-64 km), exhibiting peak-to-peak amplitudes of up to 2°-3° K and periods from ˜ 2 weeks in midstratosphere to ˜ 1 week at higher altitudes. Faster Kelvin waves with periods of 3-5 days are also found in the lower mesosphere. Height versus time plots reveal downward phase and upward group velocities, consistent with forcing from below. Vertical wavelengths are ˜ 20 km for the slower mode and about twice this scale for the faster 3 to 5-day mode. The features are trapped within ±10°-15° of the equator. Kelvin wave signatures in ISAMS and MLS temperatures are compared at 10 and 1 hPa. Good agreement is found, illustrating the internal consistency and ability of both ISAMS and MLS temperature grids to capture relatively small amplitude features with space-time scales of fast, zonally asymmetric equatorial modes.

  12. Observations of Natural and Artificial Airglow in the Mesosphere at the 56äaN latitude

    NASA Astrophysics Data System (ADS)

    Kagan, L. M.; Nicolls, M. J.; Kelley, M. C.

    In a recent paper Kagan et al Phys Rev Lett 9494 9 095004 2005 we have reported vibrationally excited OH 9-3 Meinel band emissions generated by high-power radiowaves launched by the Sura facility in Russia 56 10 r N 44 20 r E The key in these observations is that the light detected in a 2 nm wide filter centered on 630 nm was seen 1-2 s after launching radiowaves This short response and the behavior of the 630-nm emission intensity during the heating cycle rule out the 630 nm emission from atomic oxygen Several minutes after on the same night and with the same 630 0 -1 -nm filter we observed a natural phenomenon seen as an intensity depletion stretched in the east-west direction to the north of the Sura facility Next night we observed the similar event with two filters 557 7 -1 - and 630 0 -1 -nm accompanied by weak gravity wave activity There were tropospheric clouds part of the night but for the clear sky conditions the abovementioned natural phenomenon reminded mesospheric bores First reported by Taylor et al Geophys Res Lett 22 20 2849-2852 1995 as a spectacular gravity wave event this phenomenon was attributed to an internal undular bore in mesosphere by Dewan and Picard J Geophys Res 103 D6 6295-6305 1998 who later outlined the necessary conditions for mesospheric bores Dewan and Picard J Geophys Res 106 D3 2921-2927 2001 The hydroxyl and OI 557 7 nm emissions naturally occur centered on 87 km and 95 km

  13. Seasonal Variability in OH Mesospheric Temperatures at Low-Latitudes and Comparison with Timed-Saber Temperatures

    NASA Astrophysics Data System (ADS)

    Taylor,