Layered Phenomena in the Mesopause Region

Transcription

1 LPMR-10 The Tenth International Workshop on Layered Phenomena in the Mesopause Region October 24-27, 2011 Blacksburg, Virginia

2 LPMR-10 The Tenth International Workshop on LAYERED PHENOMENA IN THE MESOPAUSE REGION October 24-27, 2011 Blacksburg, Virginia Workshop Program SPONSERED BY: International Commission on the Middle Atmosphere (ICMA) Scientific Committee on Solar-Terrestrial Physics (SCOSTEP) National Aeronautics and Space Administration (NASA) National Science Foundation (NSF) Center for Space Science and Engineering Research, Virginia Tech Bradley Department of Electrical and Computer Engineering, Virginia Tech LPMR-10 Agenda 1 5

3 Monday, 24 October :30 pm - Welcome Gathering LATHAM BALLROOM D&E AT THE INN AT VIRGINIA TECH Tuesday, 25 October 2011 SOLITUDE CONFERENCE ROOM AT THE INN AT VIRGINIA TECH (Posters will be on Display Through Thursday in Cascade Conference Room) 8:30 9:00 Registration and Breakfast 9:00 9:05 Welcome and Opening Remarks Bailey Session 1: New Observations and Techniques 9:05 9:25 AIM/CIPS Observations: An Overview Randall 9:25 9:45 Lidar Observations of Polar Mesospheric Clouds, Fe Layers and Temperatures from McMurdo, Antarctica Chu 9:45 10:05 First results from the IAP Fe-Lidar in Davis, Antarctica Lübken 10:05 10:25 Nadir and Limb Viewing Observations of Polar Mesospheric Clouds from the Aeronomy of Ice in the Mesosphere (AIM) Explorer Bailey 10:25 10:50 Break and Refreshments Session 2: Sources and Formation of Ice Clouds 10:50 11:10 NLC interannual variability - who's in charge? Gumbel 11:10 11:30 Minimal impact of condensation nuclei characteristics on observable Mesospheric ice properties Megner 11:30 11:50 The PHOCUS Project: First Results Hedin 11:50 12:10 In-situ measurements of meteroric smoke properties during the Geminids 2010 Rapp 12:10 1:00 Lunch 1:00 1:20 Investigation of Dusty Space Plasmas in the Near-Earth Space Environment 1:20 1:40 The variability of PMCs and their environment in both hemispheres from SOFIE observations Mahmoudian Hervig LPMR-10 Agenda 2 5

4 1:40 2:00 Bright Arctic PMCs Formed by Exhaust from the Space Shuttle's Final Launch 2:00 2:20 Daily spatial correspondences between CIPS/AIM PMC structures and satellite measured temperature and water vapor 2:20 2:40 PMC Observations from OMI Compared with Coincident Temperature and Water Vapor Measurements from MLS 2:40 3:00 On the onset of polar mesospheric cloud seasons as observed by SBUV Stevens Rong Shettle Benze 3:00 3:30 Break and Refreshments Session 3: Horizontal Structure and Dynamics 3:30 3:50 Nadir Observations in the Limb Llewellyn 3:50 4:10 CIPS Orbit to Orbit Correlation McNabb 4:10 4:30 Small scale structures in NLC observed by lidar Kaifler 4:30-4:50 Horizontally resolved structures of polar mesospheric echoes obtained with MAARSY Latteck 4:50-5:10 Comparing OSIRIS tomography with CIPS imaging Hultgren 5:10-5:30 Aircraft & satellite observations of NLC Reimuller 6:00 pm Dinner at Lane Stadium in the South End Zone LPMR-10 Agenda 3 5

5 Wednesday, 26 October 2011 SOLITUDE CONFERENCE ROOM AT THE INN AT VIRGINIA TECH 8:30 9:00 Registration and Breakfast Session 4: Dynamic Influences 9:00 9:20 Coupling processes of the middle atmosphere circulation in a simple model 9:20 9:40 On the onset of polar mesospheric clouds and the breakdown of the stratospheric polar vortex in the southern hemisphere 9:40 10:00 Gravity Wave Fine Structure Dynamics and Instability in the MLT 10:00 10:20 Implications of Gravity Wave Fine Structure Interactions for NLC Distributions as Tracers of Small-Scale Dynamics 10:20 10:50 Break and Refreshments 10:50-11:10 Gravity waves and ozone perturbations near the stratopause observed from the CIPS instrument Körnich Karlsson Fritts Fritts Carstens 11:10 11:30 Morphology of Polar Mesospheric Clouds as Seen From Space Thurairajah 11:30 11:50 Comparison of northern and southern hemisphere gravity wave activity and characteristics as observed in polar mesospheric clouds imaged by the AIM satellite 11:50-12:10 Seasonal and nocturnal variations of the OH emission layer at low latitudes 12:10-12:30 Noctilucent clouds and the background atmosphere above ALOMAR 12:30-02:00 Lunch and Poster Session Posters Cascade Conference Room P1.1 Relationships between meteoric smoke extinctions in the mesosphere and polar mesospheric clouds using measurements made by the SOFIE instrument on the AIM satellite P1.2 CIPS observation of PMCs during the Northern Hemisphere and Southern Hemisphere Seasons 2:00-3:00 Keynote Talk: Observations of PMC/NLC Science Over Four Decades 3:30 pm Excursion to Chateau Morrisette Taylor Zhao Fiedler Ramirez Thurairajah John Olivero LPMR-10 Agenda 4 5

6 Thursday, 27 October 2011 SOLITUDE CONFERENCE ROOM AT THE INN AT VIRGINIA TECH 8:30 9:00 Registration and Breakfast Session 5: Long Term Trends 9:00 9:20 45 years optical NLC observations from space platforms - what have we learned? 9:20 9:40 Temperature and ice layer trends from LIMA Lübken 9:40 10:00 Ice Water Content from SME to AIM: Some Preliminary Results Thomas 10:00 10:20 Updated PMC Trends Derived from SBUV Data DeLand 10:20 10:50 Break and Refreshments 10:50-11:10 A unified PMC/NLC Database: Some issues and a Proposal Thomas 11:10 12:00 General discussion and Business Meeting 12:00 1:00 Lunch Witt LPMR-10 Agenda 5 5

7 LPMR-10 The Tenth International Workshop on LAYERED PHENOMENA IN THE MESOPAUSE REGION October 24-27, 2011 Blacksburg, Virginia Workshop Abstracts (in alphabetic order) SPONSERED BY: International Commission on the Middle Atmosphere (ICMA) Scientific Committee on Solar-Terrestrial Physics (SCOSTEP) National Aeronautics and Space Administration (NASA) National Science Foundation (NSF) Center for Space Science and Engineering Research, Virginia Tech Bradley Department of Electrical and Computer Engineering, Virginia Tech LPMR-10 Abstracts 1 36

8 Nadir and Limb Viewing Observations of Polar Mesospheric Clouds from the Aeronomy of Ice in the Mesosphere (AIM) Explorer (Session 1: 25 October 2011, Tuesday Morning) Scott M. Bailey, Cora E. Randall, Gary E. Thomas, Jerry D. Lumpe, Mark E. Hervig & James M. Russell, III The Cloud Imaging and Particle Size (CIPS) instrument on the AIM spacecraft is a 4-camera nadir pointed imager with a bandpass centered at 265 nm and a field of view of 120 by 80 degrees. CIPS observes Polar Mesospheric Clouds (PMCs) against the sunlit Rayleigh-scattered background. At individual polar locations approximately 5km by 5km in area, CIPS observes the same volume of air multiple times over a range of scattering angles from about 35 to 150 degrees. These multi-angle observations allow the identification and extraction of the PMC scattered radiance from the Rayleigh-scattered background. From this is obtained the ice albedo and particle size. At the summer terminator on each orbit, the Solar Occultation For Ice Experiment (SOFIE) views a common cloud volume with CIPS. SOFIE uses IR solar occultation in 16 channels (.3 to 5 microns) to obtain ice properties in addition to temperature, water vapor abundance, and other environmental parameters. In this talk, we discuss comparisons of the CIPS and SOFIE observations. We show that CIPS reveals significant structure along the limb path observed by SOFIE. We use SOFIE retrieved cloud parameters to make predictions of CIPS common volume-average observations and compare those to the actual CIPS data. The data show excellent correlation, but some systematic differences. We present evidence that those systematic differences are related to the use of laboratory-measured ice properties in the CIPS and SOFIE retrievals. Corresponding Author: Scott Bailey, Virginia Tech, baileys@vt.edu LPMR-10 Abstracts 2 36

9 On the onset of polar mesospheric cloud seasons as observed by SBUV (Session 2: 25 October 2011, Tuesday Afternoon) Ms. Susanne Benze, Mrs. Cora E. Randall, Mrs. Bodil Karlsson, Ms. Lynn Harvey, Mr. Gary E. Thomas, Mr. Eric P. Shettle & Mr. Matthew T. DeLand This presentation describes an investigation using data from the Solar Backscatter Ultraviolet (SBUV) satellite instruments to explore and understand variations in the timing of the onset of Polar Mesospheric Cloud (PMC) seasons. Previous work has shown that for several recent southern hemisphere (SH) seasons observed by the Aeronomy of Ice in the Mesosphere (AIM) mission [Karlsson et al., 2011] and the Optical Spectrograph and InfraRed Imaging System (OSIRIS) [Gumbel and Karlsson, 2011], the PMC season onset was controlled by the timing of the shift from winter to summer zonal wind flow in the SH stratosphere. This work places those results into a historical context by extending the analysis to 27 years of PMC observations from the SBUV instruments, including both hemispheres. The start date of the SH seasons correlates very well with the timing of the SH stratospheric zonal wind shift, over the entire 27-year period. Additional results show that the solar cycle plays a minor role in modulating the SH PMC season onset. Neither the northern hemisphere (NH) stratospheric wind strength at PMC season start nor the timing of the wind switch correlate with the NH season start. In the NH, the solar cycle seems to be the dominant controlling factor, but other processes cause higher frequency variations in the NH PMC season onset. References: Gumbel, J. and Karlsson, B., Intra- and inter-hemispheric coupling effects on the polar summer mesosphere. Geophysical Research Letters, Vol. 38, L14804, doi: /2011gl Karlsson, B., Randall, C. E., Shepherd, T. G., Harvey, V. L., Lumpe, J. D., Nielsen, K., Bailey, S. M., Hervig, M. E., and Russell III, J. M., On the seasonal onset of polar mesospheric clouds and the breakdown of the stratospheric polar vortex in the southern hemisphere. Journal of Geophysical Research, doi: /2011jd015989, in press. Corresponding Author: Susanne Benze, Laboratory for Atmospheric and Space Physics, University of Colorado, susanne.benze@lasp.colorado.edu LPMR-10 Abstracts 3 36

10 Gravity waves and ozone perturbations near the stratopause observed from the CIPS instrument (Session 4: 26 October 2011, Wednesday Morning) Mr. Justin N. Carstens, Dr. Michael J. Taylor, Dr. Yucheng Zhao, Dr. Scott Bailey, Dr. Jerry Lumpe, Dr. Cora Randall, Dr. Brentha Thurairajah & Dr. James M. Russell Observations from the Cloud Imaging and Particle Size (CIPS) instrument have been analyzed for the presence of gravity waves and other perturbations in the ozone signal near the stratopause. The CIPS instrument is onboard the Aeronomy of Ice in the Mesosphere (AIM) satellite. CIPS is a nadir imager with an approximately 2000 km along track by 1000 km cross track field of view, and it observes at the UV wavelength of 265nm with a spatial resolution of 1km by 2km. The primary goal of CIPS is to image and determine the particle size of ice in Polar Mesospheric Clouds (PMCs), so observations are made in the spring and summer hemisphere at latitudes poleward of approximately 35 degrees. When PMCs are not present, the observed signal is due to Rayleigh scattered sunlight and is strongly controlled by ozone absorption. Perturbations in the ozone density near 55 km show up as structures in the non-pmc images. This work will present an initial analysis of the perturbation in the observed ozone column density at a horizontal resolution of 20 km. Structures in the images are common, ranging from 60 km horizontal wavelength gravity waves to large scale structures spanning the polar cap. Many waves tend to appear in hot spots such as over the Antarctic Peninsula indicating mountain waves, while others can be correlated with large storms. Corresponding Author: Justin Carstens, Virginia Tech, jcar@vt.edu LPMR-10 Abstracts 4 36

11 Lidar Observations of Polar Mesospheric Clouds, Fe Layers and Temperatures from McMurdo, Antarctica (Session 1: 25 October 2011, Tuesday Morning) Professor Xinzhao Chu, Dr. Wentao Huang, Mr. Zhibin Yu, Mr. Weichun Fong, Mr. Cao Chen, Mr. Zhangjun Wang, Mr. John A. Smith & Professor Chester S. Gardner Despite the success of lidar observations at the South Pole and near the Antarctic Circle at Rothera, Davis and Syowa stations, a critical data gap existed in latitude between 90 S and 69 S. To help fill this gap, during the austral summer of , we deployed an Fe Boltzmann temperature lidar to McMurdo Station (77.83 S, E), half way between the South Pole and Antarctic Circle. This lidar was originally developed at the University of Illinois by Chu, Gardner and co-workers and deployed to the South Pole ( ) and Rothera ( ). Recently it was refurbished and upgraded at the University of Colorado. With the support and collaboration of the United States Antarctic Program (USAP) and the Antarctic New Zealand (AntNZ), the University of Colorado lidar group installed the Fe lidar into the AntNZ facility at Arrival Heights, McMurdo in late This lidar has full diurnal coverage and is capable of detecting polar mesospheric clouds (PMCs), meteoric Fe layers, and temperatures under full sunlight. Following installation, it was operated around the clock, weather permitting. In this paper we report the first lidar observations of polar middle and upper atmosphere at McMurdo, Antarctica, and present the newest science discoveries. PMC data in the first summer season of confirm previous reports of the inter-hemispheric difference in PMC mean centroid altitude. By combining the McMurdo observations with those obtained at the South Pole and Rothera, we find that the latitudinal dependence of mean PMC altitude is statistically significant with a slope of 40 ± 3 m/deg. Lidar observations provide direct evidence that the cold phase of wave-induced temperature oscillations facilitates PMC formation and Fe depletion. Frequent occurrence of sporadic Fe layers and extremely active variations of main Fe layers are also unique among other lidar observations of metal species. Some of these results challenge our understanding of the upper atmosphere composition, chemistry, dynamics and thermal structure. Corresponding Author: Xinzhao Chu, University of Colorado, xinzhao.chu@colorado.edu LPMR-10 Abstracts 5 36

12 Updated PMC Trends Derived from SBUV Data (Session 5: 27 October 2011, Thursday Morning) Mr. Matthew T. DeLand, Mr. Eric P. Shettle, Dr. Gary E. Thomas & Dr. John J. Olivero SBUV instruments have been observing PMCs from space continuously since November This data record now covers more than 32 years, and four such instruments are currently operating to extend these data into the future. While each instrument is nominally launched into a Sun-synchronous orbit, spacecraft drift leads to significant changes in local time and viewing conditions (i.e. scattering angle) for the PMC measurements during the lifetime of each instrument. These changes need to be considered in the creation of a merged data set suitable for determining long-term trends. Our previous analysis of the SBUV PMC data found that longterm variations in PMC brightness and occurrence frequency were anti-correlated with solar activity, and that an increasing secular trend was present at most latitudes. We have recently revised the SBUV PMC detection algorithm to use a brightness threshold that varies with scattering angle, rather than with latitude. This represents a simplified implementation of the variation in PMC brightness predicted by Mie scattering theory for small ice particles. We will use these results to re-examine the local time adjustments determined from SBUV data that were applied in our previous trend analysis. We will also consider the local time dependence results that we recently derived from OMI PMC measurements. This paper will show updated trend results using SBUV data through the NH 2011 season. Corresponding Author: Matthew DeLand, Science Systems and Applications Inc. (SSAI), matthew_deland@ssaihq.com LPMR-10 Abstracts 6 36

13 Noctilucent clouds and the background atmosphere above ALOMAR (Session 4: 26 October 2011, Wednesday Morning) Dr. Jens Fiedler, Dr. Gerd Baumgarten, Dr. Uwe Berger, Dr. Peter Hoffmann, Mrs. Natalie Kaifler & Professor Franz-Josef Lübken Noctilucent clouds (NLC) are the visible manifestation of ice particles persistently present in the polar summer mesopause region. Their formation is a rather complicated physical process depending on atmospheric background parameters, such as temperature and water vapor, which are hardly to measure directly at the altitudes of interest. This makes NLC an attractive tracer for dynamic processes in the atmosphere. Between 1997 and 2010 NLC have been observed by the ALOMAR Rayleigh/Mie/Raman (RMR) lidar in Northern Norway at 69N, 16E. During a total of 4340 measurement hours NLC were detected for more than 1850 hours on 440 different days, which is the largest NLC data base acquired by lidar. Collocated MF-radar measurements and calculations with the Leibniz- Institute Middle Atmosphere (LIMA-) model are used to characterize the background atmosphere. Temperature as well as horizontal winds at 83 km altitude show distinct differences during NLC observations compared to when NLC are absent: On seasonal mean it is colder and the winds are stronger westward when NLC are detected. The wind separation shows up in measurement as well as model and it is consistent with the current understanding that lower temperatures support the existence of ice particles. For the whole 14-years data set there is no statistically significant relation between NLC occurrence and solar Lyman-alpha radiation. The reason is that between 2005 and 2008 both parameters were almost in-phase, contrary to the other years. On the other hand NLC occurrence and temperature at 83 km show a significant anti-correlation, which suggests that the thermal state plays a major role for the existence of ice particles and dominates the pure Lyman-alpha influence on water vapor during certain years. NLC above ALOMAR are strongly influenced by atmospheric tides. Faint clouds occur most often compared to the other cloud classes but the occurrence variability is largest for strong clouds. The cloud water content varies by a factor of 2.8 over the diurnal cycle. Depending on the NLC parameter, diurnal and semidiurnal amplitudes and phases have different and partly strong year-to-year variations. Most striking features are shown by the NLC brightness: The semidiurnal amplitude has very low values during solar maximum and is over a period of 10 years significantly anti-correlated to Lyman-alpha radiation. The diurnal phase increases monotonic over the whole time series. In general, amplitudes as well as phases of NLC parameters are not constant over the years. They rather vary in a different manner: Amplitudes can change by a factor of more than 3 and phases show changes up to 7 hours. Such variability could impact long-term NLC observations which do not cover the full diurnal cycle. Corresponding Author: Jens Fiedler, Leibniz Institute of Atmospheric Physics, fiedler@iap-kborn.de LPMR-10 Abstracts 7 36

14 Gravity Wave Fine Structure Dynamics and Instability in the MLT (Session 4: 26 October 2011, Wednesday Morning) Dr. Dave Fritts This talk will describe the consequences of the superposition of a large-scale gravity wave and oscillatory fine structure shears representative of inertia-gravity waves at smaller vertical scales. The dynamics of such flows have important implications for fine structure and turbulence evolutions, which depend very strongly on the relative orientations of the initial motions. When the gravity wave propagation direction and fine structure shears are aligned, strong deformations result which drive strong wave-wave interactions and excitation of other larger-scale motions, but with relatively weak turbulence generation. When the gravity wave propagation direction and fine structure shears are orthogonal, flow deformation and wave-wave interactions are weak, but turbulence generation is very strong, due to stretching of fine-structure vorticity by the gravity wave. The resulting turbulence is highly anisotropic, with various implications for measurements of these dynamics. Corresponding Author: David Fritts, Colorado Research Associates, Northwest Research Associates, dave@cora.nwra.com LPMR-10 Abstracts 8 36

15 Implications of Gravity Wave Fine Structure Interactions for NLC Distributions as Tracers of Small-Scale Dynamics (Session 4: 26 October 2011, Wednesday Morning) Dr. Dave Fritts My first talk described the dynamics accompanying gravity wave fine structure superpositions and interactions. These were seen to yield various instabilities, including localized shear instability and wave breaking, occasionally occurring at the same time in different locations within the flow. The nature of these instabilities often compresses layers in the atmosphere, enabling NLC layers having finite nominal widths in the right locations to nevertheless provide sensitivity to instability dynamics at relatively small spatial scales. We explore the implications of NLC optical depth (or brightness) as a tracer of such motions in the limit where motions occur sufficiently rapidly to preclude changes in particle radius. If these prove useful as diagnostics of small-scale instabilities and turbulence, particle tracking methods will enable us to expand such studies to include multiple influences on cloud particles, including sedimentation, ablation due to warming, and growth due to cooling and increasing vapor pressure. Corresponding Author: David Fritts, Colorado Research Associates, Northwest Research Associates, dave@cora.nwra.com LPMR-10 Abstracts 9 36

16 NLC interannual variability - who's in charge? (Session 2: 25 October 2011, Tuesday Morning) Dr. Jörg Gumbel, Dr. Bodil Karlsson, Dr. Linda Megner, Mr. Kristoffer Hultgren & Dr. Heiner Körnich What controls the interannual variability of noctilucent clouds? There are datasets showing a dominant effect of the solar cycle. There are datasets showing a dominant effect of global dynamical coupling. Is there a contradiction? We use ten years of Odin data to take a closer look. Corresponding Author: Jörg Gumbel, Stockholm University, gumbel@misu.su.se LPMR-10 Abstracts 10 36

17 The PHOCUS Project: First Results (Session 2: 25 October 2011, Tuesday Morning) Dr. Jonas Hedin and the PHOCUS team On the morning of July 21, 2011, the PHOCUS sounding rocket was launched from Esrange, Sweden, into a strong noctilucent cloud observed by the EsrangeLidar. The aim with the PHOCUS project (Particles, Hydrogen and Oxygen Chemistry in the Upper Summer mesosphere) is to study mesospheric particles (ice and 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. Here we will describe the PHOCUS experiments and present first 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 groundbased instrumentation included the Esrangelidar, the ESRAD MST radar, the SkiYMET meteor radar and EISCAT. Corresponding Author: Jonas Hedin, Stockholm University, jonash@misu.su.se LPMR-10 Abstracts 11 36

18 The variability of PMCs and their environment in both hemispheres from SOFIE observations (Session 2: 25 October 2011, Tuesday Afternoon) Dr. Mark Hervig The variability of polar mesospheric clouds (PMC) and their environment is examined for nine summer seasons observed by the Solar Occultation For Ice Experiment (SOFIE) in both hemispheres. The results indicate that higher column ice water content (IWC) is associated with both lower temperatures and higher clear sky water vapor. Comparing polar summer observations in clear skies to those with PMCs present, indicates that column water vapor is higher (9% in the South and 18% in the North) and that temperatures are warmer (~6 K in the South and ~3 K in the North) in clear skies. The observed IWC variability is broadly explained using temperature and water vapor in terms of saturation ratio. However, the saturation difference (water vapor mixing ratio saturation mixing ratio) is found to reliably explain the observed IWC variability. Corresponding Author: Mark Hervig, GATS Inc, m.e.hervig@gats-inc.com LPMR-10 Abstracts 12 36

19 Comparing OSIRIS tomography with CIPS imaging (Session 3: 25 October 2011, Tuesday Afternoon) Mr. Kristoffer Hultgren, Professor Jörg Gumbel, Professor Doug Degenstein, Professor Adam Bourassa & Dr. Nick Lloyd The Optical Spectrograph and InfraRed Imager System (OSIRIS) onboard Odin and the Cloud Imager and Particle Size instrument (CIPS) onboard AIM provide complementary scattered light measurements of polar mesospheric clouds. While OSIRIS applies limb geometry and spectral analysis, CIPS applies downward observations and phase function analysis. On a total of twelwe days during the northern hemisphere summers 2010 and 2011, Odin was operated in a special mesospheric mode with short limb scans limited to altitude range of polar mesospheric clouds. For OSIRIS this provides multiple views through a given cloud volume and, thus, a basis for tomographic analysis of the vertical/horizontal cloud structure. Here we present retrieved cloud structures by Odin/OSIRIS and compare these with common volume measurements by AIM/CIPS. Corresponding Author: Kristoffer Hultgren, Stockholm University, kristofferh@misu.su.se LPMR-10 Abstracts 13 36

20 Small scale structures in NLC observed by lidar (Session 3: 25 October 2011, Tuesday Afternoon) Mrs. Natalie Kaifler, Dr. Gerd Baumgarten, Dr. Jens Fiedler & Professor Franz-Josef Lübken Since the early observations noctilucent clouds (NLC) are known for the rich fine structure that can be observed even by eye and was later studied using cameras. Small scale structures can be generated by e.g. breaking gravity waves, a process relevant to the energy budget of the summer mesopause region. Observations in high resolution therefore allow to study small scale processes that contribute to the understanding of the physical processes relevant in this part of the atmosphere. The exact determination of the NLC altitude is however difficult with cameras as well as satellite instruments. With lidar technology a technique has become available that allows to determine the altitude and brightness of NLC directly at a single location. We want to address the question of how high a temporal resolution we can achieve today and what can be learned from it. We use data obtained by the Rayleigh-/Mie-/Raman lidar at the ALOMAR facility in Northern Norway (69N). During the years , the lidar was run in a 30 s integration mode which allows to study small scale structures in greater detail than before. Being a twin lidar with two beams separated by 40 km at NLC altitude, it is possible to compare NLC altitudes at two different locations and we find that on average the NLC layer is at the same altitude, meaning there is no general tilt of the NLC layers that are advected with the wind speed through the lidar beams. At single times however the altitudes can be different by up to 1 km. Time series of NLC altitude also reveal fast changes with a period of minutes and amplitudes in the order of or greater than the NLC layer width. Additionally, brightness profiles show structures in the vertical as well, e.g. double peaks that occur in approximately 10 % of all NLC observations and a mean vertical seperation of about 1.6 km. We detect these structures and analyze time series of NLC layer altitude and variations in brightness using wavelet analysis, revealing spectral slopes in agreement with a -5/3 slope. To find the maximum temporal resolution possible with this instrument, we have recently installed a single shot acquisition system and present first results of spectral signals down to a range of 10 seconds. Corresponding Author: Natalie Kaifler, Leibniz Institute of Atmospheric Physics, n.kaifler@iap-kborn.de LPMR-10 Abstracts 14 36

21 On the onset of polar mesospheric clouds and the breakdown of the stratospheric polar vortex in the southern hemisphere (Session 4: 26 October 2011, Wednesday Morning) Dr. Bodil Karlsson, Professor Cora Randall & Professor Theodore Shepherd Southern hemisphere (SH) polar mesospheric clouds have been observed to be more variable and, in general, dimmer than their northern hemisphere (NH) counterpart. The precise cause of these hemispheric differences is not well understood. This presentation discusses observations from the AIM satellite, which indicate that in recent years the date on which the PMC season begins varies much more in the SH than in the NH. Using the Canadian Middle Atmosphere Model, we show that the generation of sufficiently low temperatures necessary for cloud formation in the SH summer polar mesosphere is perturbed by variations in the timing of the late-spring breakdown of the SH stratospheric polar vortex. These stratospheric variations influence the propagation of gravity waves up to the mesosphere, thereby adding a stratospheric control to the temperatures in the summer polar mesopause region, which causes the onset of PMCs to vary from one year to another. This effect is much stronger in the SH than in the NH because the breakdown of the polar vortex occurs much later in the SH, closer in time to the PMC season. The same effect may help explain why PMCs are generally dimmer in the SH than in the NH. Corresponding Author: Bodil Karlsson, Stockholm University, bodil@misu.su.se LPMR-10 Abstracts 15 36

22 Coupling processes of the middle atmosphere circulation in a simple model (Session 4: 26 October 2011, Wednesday Morning) Dr. Heiner Körnich, Dr. Bodil Karlsson & Dr. Jörg Gumbel The mesospheric pole-to-pole circulation gives rise to polar temperatures which are far from the radiative equilibrium. In the summer mesopause region the very low temperatures allow noctilucent clouds to form. The mesospheric circulation is mainly driven by breaking gravity waves which propagate upwards from the lower atmosphere. During the propagation, the gravity waves are subject to filtering in the stratospheric flow. This filtering exerts a remote forcing on the mesospheric circulation and can lead to substantial variations in the strength of the mesospheric circulation and corresponding noctilucent cloud occurrence. An idealized model of the mesospheric general circulation was constructed to contain the main ingredients of this vertical coupling, i.e. parametrized gravity waves launched in the lower atmosphere, a prescribed stratospheric mean flow, and a zonally symmetric mesospheric circulation. The model was successfully applied to prove the mechanism of the so-called interhemispheric coupling which plays a dominant role for the interannual variability of the mean mid-season noctilucent cloud occurrence. In the current work, we apply the model to examine further details of the interhemispheric coupling, e.g. the time-scale, and how other background anomalies can affect the mesospheric pole-to-pole circulation. Specifically, we are interested in the dynamical response of the circulation to intrahemispheric differences in the stratospheric flow, the Quasi-Biennial Oscillation, and stratospheric wind changes due to the solar cycle. Corresponding Author: Heiner Körnich, Stockholm University, heiner@misu.su.se LPMR-10 Abstracts 16 36

23 Horizontally resolved structures of polar mesospheric echoes obtained with MAARSY (Session 3: 25 October 2011, Tuesday Afternoon) Dr. Ralph Latteck, Professor Markus Rapp, Dr. Werner Singer & Dr. Gunter Stober The Leibniz-Institute of Atmospheric Physics in Kühlungsborn, Germany (IAP) installed a new powerful VHF radar on the North-Norwegian island Andøya (69.30N, 16.04E) in 2009/2010. The new Middle Atmosphere Alomar Radar System (MAARSY) replaces the existing ALWIN radar which has been in continuous operation on Andøya for more than 10 years. MAARSY is a monostatic radar operated at 53.5MHz with an active phased array antenna consisting of 433 Yagi antennas each connected to its own transceiver with independent control of frequency, phase and power of the transmitted signal. This arrangement provides a very high flexibility of beam forming and beam steering and allows classical beam swinging operation as well as experiments with simultaneous multiple beams and the use of modern interferometric applications for improved studies of the Arctic atmosphere from the troposphere up to the lower thermosphere with high spatial-temporal resolution. The installation of the antenna array was completed in August The radar control and data acquisition hardware as well as an initial expansion stage of 196 transceiver modules was installed in spring 2010, upgraded to 343 transceiver modules in December 2010 and was completed to full operation in spring Beside standard observations of tropospheric winds and Polar Mesosphere Summer Echoes, the first multi-beam experiments using up to 91 beams quasi-simultaneously in the mesosphere have been carried out using the different expansion stages of the system in summer and winter These results provide a first insight into the horizontal variability of Polar Mesosphere Summer and Winter Echoes in an area of about 80 km by 80 km with time resolutions between 3 and 9 minutes. Corresponding Author: Ralph Latteck, Leibniz Institute of Atmospheric Physics, latteck@iapkborn.de LPMR-10 Abstracts 17 36

24 Nadir Observations in the Limb (Session 3: 25 October 2011, Tuesday Afternoon) E.J. Llewellyn, L. Rieger, A.E. Bourassa, P.E. Sheese, R.L. Gattinger, N.D. Lloyd, I.C. McDade, W.F.J. Evans, and D.A. Degenstein The OSIRIS instrument on the Odin satellite has provided almost continuous atmospheric limb observations since it was launched in February During that time it has provided new information on Polar Mesospheric Clouds (PMC). The early mission observations provided information on PMC frequency and altitude in both the northern and southern hemispheres as well as data on particle size. Recently the observations of the oxygen airglow A-band emission at 762 nm have been used to derive atmospheric temperature profiles; these observations have shown that the temperature above PMC is much colder than previously supposed. However, while we have also used the OSIRIS observations in the vicinity of PMC to study the spectrum of the radiation scattered from the clouds. This radiation includes airglow emissions as well as PMC scattering of the upwelling albedo radiation and the illuminating solar radiation. Thus it is expected that the spectral signature of the PMC radiation will include both albedo information as well that of any absorbing gases in the atmospheric column below the PMC. In this presentation we will report on the latest mesospheric temperature measurements in the vicinity of PMC. We will also present some very new, and very surprising, results that we have obtained from a DOAS analysis of spectra of the PMC scattered light. Corresponding Author: E.J. Llewellyn, ISAS, University of Saskatchewan, edward.llewellyn@usask.ca LPMR-10 Abstracts 18 36

25 First results from the IAP Fe-Lidar in Davis, Antarctica (Session 1: 25 October 2011, Tuesday Morning) Professor Franz-Josef Lübken, Dr. Josef Höffner, Mr. Bernd Kaifler, Mr. Timo Viehl & Dr. Ray Morris We report the first simultaneous measurements of temperatures by a mobile Fe resonance lidar and polar mesosphere summer echoes (PMSE) by a VHF radar both located at Davis, Antarctica (69 S, 78 E). The lidar was installed at Davis in December 2010 and measures temperatures in the iron layer, i. e. approximately from 80 to 100~km. It is based on probing the Doppler broadened resonance line of iron atoms and can operate under daylight conditions. Typical values for temperature uncertainty, altitude and time resolutions are 3-5 K, 1 km, and 1 hour, respectively. The 55 MHz VHF radar performs measurements since February Several hours of simultaneous lidar/radar observations are now available from the Antarctic summer season 2010/2011. Ice particles in the summer mesosphere can be detected by lidar (`noctilucent clouds', NLC) and also create strong radar echoes known as PMSE. The existence of ice particles relies on temperatures being lower than the frost point temperature. Temperatures measured by our Fe lidar are generally very low in the mesopause region but occasionally show some unexpected features. For example, we sometimes find the mesopause at significantly higher altitudes compared to similar latitudes in the northern hemisphere. The VHF radar frequently detects PMSE. Temperatures are below the frost point at PMSE altitudes assuming reasonable water vapor concentrations. To our surprise PMSE were persistently absent at altitudes where temperatures are much lower than the frost point. We note that (apart from low temperatures) more ingredients are required for PMSE, for example, charged ice particles of sufficient size, background electrons, neutral air turbulence etc. We present a first overview of our measurements at Davis and discuss potential explanations for the presence and absence of PMSE. We also compare with the general circulation at lower altitudes and present first measurements of thermal tides in Davis and comparison with corresponding NH observations. Corresponding Author: Franz-Josef Lübken, Leibniz Institute of Atmospheric Physics, luebken@iap-kborn.de LPMR-10 Abstracts 19 36

26 Temperature and ice layer trends from LIMA (Session 5: 27 October 2011, Thursday Morning) Professor Franz-Josef Lübken, Dr. Uwe Berger, Mr. Johannes Kiliani, Dr. Gerd Baumgarten & Dr. Jens Fiedler Ice layers in the summer mesosphere known as `noctilucent clouds' (NLC) are very sensitive to background conditions and are therefore considered to be appropriate tracers for long term variations in the middle atmosphere. We present results from our LIMA model (Leibniz Institute Middle Atmosphere Model) which nicely reproduces mean conditions of the summer mesopause region and also mean characteristics of ice layers. LIMA nudges to ECMWF data in the troposphere and lower stratosphere which influences the background conditions in the mesosphere and thereby the morphology of ice clouds. We compare our results with measurements, for example with albedos from the SBUV satellites. For trend analysis we use nearly 50 years of LIMA simulations of ice clouds in the northern and southern hemisphere, again using ECMWF data in the lower part of the model. In a first run trace gas concentrations are kept constant except for water vapor which is modified by solar radiation varying from year to year. Long term trends in temperatures and ice layer parameters are observed in the mesosphere due to stratospheric effects on the mesosphere (shrinking). We discuss results from the northern and southern hemisphere. We find, for example, that larger trends in NLC brightness or occurrence rates are not necessarily associated with larger (more negative) temperature trends. They can also be caused by larger trends of water vapor caused by larger freeze drying, which in turn can be caused by generally lower temperatures and/or more background water. We expand our simulations by including solar cycle effects on mesospheric temperatures and winds, and also long term trends in carbon dioxide and ozone in the middle atmosphere. We will present first results from these calculations. More recently we have used LIMA to study temperature trends in the mesosphere at mid latitudes and compared with trends from satellite, lidar, and phase height observations. For the first time large temperature trends in the summer mesosphere can be reproduced and explained by a model. As is shown in the presentation, stratospheric ozone has a major impact on temperature trends in the summer mesosphere. Corresponding Author: Franz-Josef Lübken, Leibniz Institute of Atmospheric Physics, luebken@iap-kborn.de LPMR-10 Abstracts 20 36

27 CIPS Orbit to Orbit Correlation (Session 3: 25 October 2011, Tuesday Afternoon) Dr. John McNabb, Dr. Scott Bailey & Dr. Cora Randall This presentation will show results of a study of measurements from the Cloud Imaging and Particle Size (CIPS) instrument on the Aeronomy of Ice in the Mesosphere (AIM) satellite. CIPS measures 265 nm radiation in a series of images during each approximately 90 minute orbit. Several overlapping images from an orbit are used to calculate the cloud albedo versus scattering angle at each geolocation and produce an albedo normalized to 90 degree scattering angle. The time between the first and last images used to calculate albedo in a single CIPS measurement is approximately 5 minutes. The correlation of measurements of this normalized albedo in regions of overlap of consecutive orbits is analyzed as a function of the number of orbits from the first of the consecutive measurements and averaged over a season. The two time scales, 5 and 90 minutes, combined with the observed correlation, provides insight into the time scales on which change occurs in Polar Mesospheric Clouds. Preliminary results will be shown, along with a discussion of implications for the understanding of Polar Mesospheric Cloud formation and plans for future work. Corresponding Author: John McNabb, Hampton University, john.mcnabb@hamptonu.edu LPMR-10 Abstracts 21 36

28 Minimal impact of condensation nuclei characteristics on observable Mesospheric ice properties (Session 2: 25 October 2011, Tuesday Morning) Dr. Linda Megner Noctilucent clouds and polar mesospheric summer echoes are both manifestations of ice particles near the summer polar mesopause. These ice particles are believed to form mainly on preexisting ice condensation nuclei. The characteristics and especially the concentrations of such nuclei have been considered important factors in determining ice properties. More ice condensation nuclei would, given the limited amount of water vapor, yield more but smaller ice particles, and thus a dimmer noctilucent cloud. However, here it is shown that the sensitivity of observable ice properties to condensation nuclei concentration is much less than one would expect from the simple situation described above. In particular, both ice mass and cloud brightness is close to independent of condensation nuclei concentration. The reason for this lack of sensitivity is investigated and leads to a picture of noctilucent cloud formation as a two step process. The first step, nucleation, is controlled by the temperature conditions at the mesopause, whereas the second step, growth of the ice particles, is controlled primarily by the water content slightly below the mesopause. Corresponding Author: Linda Megner, Stockholm University, linda@misu.su.se LPMR-10 Abstracts 22 36

29 Investigation of Dusty Space Plasmas in the Near-Earth Space Environment (Session 2: 25 October 2011, Tuesday Afternoon) Alireza Mahmoudian & Wayne Scales Dusty plasmas are rather common in space, being found in planetary rings, interstellar clouds, cometary plasma tails, and the ionosphere of the Earth and other planets. Over 40 metric tons of meteoric dust enters the earth s atmosphere every day. This dust settles and creates natural dust layers in the altitude range between 80 and 100 kilometers which spans the earth s upper mesosphere to lower thermosphere. Since these dust layers are immersed in the earth s upper atmosphere, they become charged due to collection of electrons and ions from the earth s ionospheric plasma. Noctilucent Clouds NLCs are a fascinating visual manifestation of these dust layers. So-called Polar Mesospheric Summer Echoes PMSEs are radar echoes that are a direct consequence of the sub-visible charged dust that exists at altitudes above NLC regions. Polar Mesospheric Summer Echoes (PMSE) are strong echoes that have been typically observed in the frequency range from 50MHz to 1.3GHz and in the altitude about 85km. PMSEs are produced by scattering from electron irregularities due to electron charging on the irregular subvisible mesospheric dust layer. The radar echoes occur at half the radar wavelength therefore the wavelength of the irregularities are roughly in the range of 10cm to 10m. The cause of dust density structures and their persistence over relatively long intervals (10s to 100s of milliseconds) had been an open scientific question and longtime controversial topic. The first objective of this presentation is to consider the temporal behavior of electron irregularity amplitude after turn-on and turn-off of radio wave heating. The variation of plasma parameters and their effect on electron irregularity amplitude is studied. The results described in this presentation obtained using mesospheric parameters measured in recent in-situ experiments and are based on the radar facilities frequencies which are available at EISCAT and HAARP for actual experimental predictions. The results will be compared with the data from recent active modification of PMSE experiments at 56MHz, 224MHz and 930MHz. In particular, the effect of positive dust particles on the electron irregularity amplitude has been investigated. The measured positive and negative dust particles in recent in-situ experiments are considered to study the anticorrelation and correlation of the irregularities in the electron and ion densities which shows good agreement with the experimental data. In the second part of the presentation, an analytical model to validate the computational model will be introduced and possible diagnostic information regarding the charged dust layer and plasma parameters is investigated. In the last part of the presentation, dust acoustic waves generated at the boundary layer of charged dust clouds are studied using a computational model. The similarity of these excited waves at the boundary with the data from recent in-situ experiments at the PMSE source region is discussed. Other applications will be discussed including radar echoes observed during the aerosol release space experiments and laboratory plasma experiments. Corresponding Author: Alireza Mahmoudian, Virginia Tech, mahmoudian.a@gmail.com LPMR-10 Abstracts 23 36

30 Relationships between meteoric smoke extinctions in the mesosphere and polar mesospheric clouds using measurements made by the SOFIE instrument on the AIM satellite (Poster Session: 26 October 2011, Wednesday Afternoon) Mr. David Gomez Ramirez, Dr. James M. Russell III, PhD., Dr. John W. McNabb, PhD., Dr. Mark E. Hervig, PhD. & Mr. Lance E. Deaver, M.S. Polar mesospheric clouds (PMCs) constitute a beautiful phenomenon of the upper mesosphere, one of the least accessible and studied regions of the atmosphere. These clouds have gained notoriety over the past decades because they have been varying in ways that suggest they could be an indicator of climate change. PMCs are extremely sensitive to local conditions, and it is thought that small long-term variations in their environment may lead to observable effects on the clouds. The clouds are made of water ice particles, and a crucial mechanism in their formation is nucleation. The nucleation of mesospheric ice remains an open question, and the current candidates include homogeneous nucleation and heterogeneous nucleation on meteoric smoke, sodium bicarbonate, sodium hydroxide, soot, sulfuric acid, and proton hydrates. The present consensus is that heterogeneous nucleation on meteoric smoke is the most viable candidate for the formation of PMCs. However, measurements of meteoric smoke are scarce given the small size of the particles, and until recently it has been impossible to experimentally examine any relationship between PMCs and the smoke. The Solar Occultation for Ice Experiment (SOFIE), on board the Aeronomy of Ice in the Mesosphere (AIM) satellite, performs broadband extinction measurements in 16 spectral bands organized by pairs into eight channels. Channels two and five were specifically designed to measure particle extinctions. The bands in channel two perform broadband measurements centered at the wavelengths of µm and µm while the channel five bands are centered at µm and µm. The instrument also provides broadband differential measurements between the closely adjacent spectral bands in the channel, greatly reducing errors in the signal due to instrumental, atmospheric and solar effects. Differential broadband measurements provide unprecedented accuracy in the retrieved meteoric smoke extinction even in the presence of PMCs. In an effort to better understand the nucleation mechanism for PMC formation, studies have been underway to search for possible correlations between aerosol extinction in the mesosphere and ice extinction in the cloud layer. This paper describes the data, the methodology and interim results. Corresponding Author: David Gomez Ramirez, Hampton University, david02_gr@yahoo.com.mx LPMR-10 Abstracts 24 36