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.

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

Spatial Heterodyne Imager for Mesospheric Radicals on STPSat-1

DTIC Science & Technology

2010-10-22

mesospheric OH density profiles. It also measured the Rayleigh scattered background from the clear atmosphere and solar scattering from polar mesospheric... Microwave Limb Sounder OH data shows good agreement between 60 and 90 km altitude for several latitudes and seasons. We also find good agreement of the... background signals observed by SHIMMER and MAHRSI under similar lighting conditions revealed that MAHRSI radiances are systematically smaller than

Long-term variations of polar mesospheric summer echoes observed at Andøya (69°N)

NASA Astrophysics Data System (ADS)

Latteck, R.; Bremer, J.

2017-10-01

Polar mesosphere summer echoes (PMSE) are strong radar signals received at very high radar frequencies at altitudes between about 80 and 95 km at polar latitudes during summer. PMSE are caused by inhomogeneities in the electron density of the radar Bragg scale within the plasma of the cold summer mesopause region in the presence of negatively charged ice particles. Therefore, the occurrence of PMSE depends on the ionisation due to solar wave radiation and precipitating high energetic particle fluxes but also contains information about mesospheric temperature and water vapour content. Long-time observations of these echoes can be used to conclude on long-term changes of these atmospheric parameters. Continuous observations of PMSE have been carried out on the North-Norwegian island And/oya (69.3°N, 16.0°E) using the ALOMAR SOUSY radar (1994-1997), the ALWIN VHF radar (1999-2008) and the Middle Atmosphere Alomar Radar System MAARSY (since 2011). Since both the ALWIN radar and MAARSY are calibrated systems, the received echo strength of PMSE from 17 years of mesospheric observations (1999-2016) could be converted into absolute signal power. This data series could be extended to the years 1994 until 1997 on the basis of signal-to-noise ratio values derived during the years between 1994 and 2008. Seasonal mean values of PMSE occurrence for the time period from 1 June until 31 July have been derived and the resulting 23 years long data set was analyzed in dependence on solar and geomagnetic activity as well as analyzed for long-term trends. The PMSE occurrence rate is positively correlated with the solar Lyman α radiation (however low significance level) and the geomagnetic Ap index. After elimination of the solar and geomagnetically induced parts using different regression analysis methods, the PMSE data show a significant (χ = 92%-97%) positive trend during the observation period 1994 until 2016.

Effects of Major Sudden Stratospheric Warmings Identified in Midlatitude Mesospheric Rayleigh-Scatter Lidar Temperatures

NASA Astrophysics Data System (ADS)

Sox, L.; Wickwar, V. B.; Fish, C. S.; Herron, J. P.

2014-12-01

Mesospheric temperature anomalies associated with Sudden Stratospheric Warmings (SSWs) have been observed extensively in the polar regions. However, observations of these anomalies at midlatitudes are sparse. The very dense 11-year data set, collected between 1993-2004, with the Rayleigh-scatter lidar at the Atmospheric Lidar Observatory (ALO; 41.7°N, 111.8°W) at the Center for Atmospheric and Space Sciences (CASS) on the campus of Utah State University (USU), has been carefully examined for such anomalies. The temperatures derived from these data extend over the mesosphere, from 45 to 90 km. During this period extensive data were acquired during seven major SSW events. In this work we aim to determine the characteristics of the midlatitude mesospheric temperatures during these seven major SSWs. To do this, comparisons were made between the temperature profiles on individual nights before, during, and after the SSW events and the corresponding derived climatological temperature profiles (31-day by 11-year average) for those nights. A consistent disturbance pattern was observed in the mesospheric temperatures during these SSWs. A distinct shift from the nominal winter temperature pattern to a pattern more characteristic of summer temperatures was seen in the midlatitude mesosphere close to when the zonal winds in the polar stratosphere (at 10 hPa, 60° N) reversed from eastward to westward. This shift lasted for several days. This change in pattern included coolings in the upper mesosphere, comparable to those seen in the polar regions, and warmings in the lower mesosphere.

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.

Investigating Gravity Waves in Polar Mesospheric Clouds Using Tomographic Reconstructions of AIM Satellite Imagery

NASA Astrophysics Data System (ADS)

Hart, V. P.; Taylor, M. J.; Doyle, T. E.; Zhao, Y.; Pautet, P.-D.; Carruth, B. L.; Rusch, D. W.; Russell, J. M.

2018-01-01

This research presents the first application of tomographic techniques for investigating gravity wave structures in polar mesospheric clouds (PMCs) imaged by the Cloud Imaging and Particle Size instrument on the NASA AIM satellite. Albedo data comprising consecutive PMC scenes were used to tomographically reconstruct a 3-D layer using the Partially Constrained Algebraic Reconstruction Technique algorithm and a previously developed "fanning" technique. For this pilot study, a large region (760 × 148 km) of the PMC layer (altitude 83 km) was sampled with a 2 km horizontal resolution, and an intensity weighted centroid technique was developed to create novel 2-D surface maps, characterizing the individual gravity waves as well as their altitude variability. Spectral analysis of seven selected wave events observed during the Northern Hemisphere 2007 PMC season exhibited dominant horizontal wavelengths of 60-90 km, consistent with previous studies. These tomographic analyses have enabled a broad range of new investigations. For example, a clear spatial anticorrelation was observed between the PMC albedo and wave-induced altitude changes, with higher-albedo structures aligning well with wave troughs, while low-intensity regions aligned with wave crests. This result appears to be consistent with current theories of PMC development in the mesopause region. This new tomographic imaging technique also provides valuable wave amplitude information enabling further mesospheric gravity wave investigations, including quantitative analysis of their hemispheric and interannual characteristics and variations.

Satellite observations of polar mesospheric clouds by the solar backscattered ultraviolet spectral radiometer - Evidence of a solar cycle dependence

NASA Technical Reports Server (NTRS)

Thomas, Gary E.; Mcpeters, Richard D.; Jensen, Eric J.

1991-01-01

Results are presented on eight years of satellite observations of the polar mesospheric clouds (PMCs) by the SBUV spectral radiometer, showing that PMCs occur in the summertime polar cap regions of both hemispheres and that they exhibit year-to-year variability. It was also found that the increase in the PMC occurrence frequency was inversely correlated with solar activity. Two kinds of hemispherical asymmetries could be identified: (1) PMCs in the Northern Hemisphere were significantly brighter than in the Southern Hemisphere, in accordance with previous results derived from SME data; and (2) the solar cycle response in the south is more pronounced than in the north. The paper also describes the cloud detection algorithm.

Mesospheric gravity-wave climatology at Adelaide

NASA Technical Reports Server (NTRS)

Vincent, R. A.

1986-01-01

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

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.

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

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.

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

NASA Astrophysics Data System (ADS)

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

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

Stratospheric effects on trends of mesospheric ice clouds (Invited)

NASA Astrophysics Data System (ADS)

Luebken, F.; Baumgarten, G.; Berger, U.

2009-12-01

Ice layers in the summer mesosphere at middle and polar latitudes appear as `noctilucent clouds' (NLC) and `polar mesosphere clouds'(PMC) when observed by optical methods from the ground or from satellites, respectively. A newly developed model of the atmosphere called LIMA (Leibniz Institute Middle Atmosphere Model) nicely reproduces the mean conditions of the summer mesopause region and is used to study the ice layer morphology (LIMA/ice). LIMA nudges to ECMWF data in the troposphere and lower stratosphere which influences the background conditions in the mesosphere and ice cloud morphology. Since ice layer formation is very sensitive to the thermal structure of the mesopause region the morphology of NLC and PMC is frequently discussed in terms of long term variations. Model runs of LIMA/ice are now available for 1961 until 2008. A strong correlation between temperatures and PMC altitudes is observed. Applied to historical measurements this gives negligible temperature trends at PMC altitudes (approximately 0.01-0.02 K/y). Trace gas concentrations are kept constant in LIMA except for water vapor which is modified by variable solar radiation. Still, long term trends in temperatures and ice layer parameters are observed, consistent with observations. We present results regarding inter-annual variability of upper mesosphere temperatures, water vapor, and ice clouds, and also long term variations. We compare our model results with satellite borne and lidar observations including some record high NLC parameters measured in the summer season of 2009. The latitudinal dependence of trends and ice layer parameters is discussed, including a NH/SH comparison. We will present an explanation of the trends in the background atmosphere and ice layer parameters.

Solar cycle variations in mesospheric carbon monoxide

NASA Astrophysics Data System (ADS)

Lee, Jae N.; Wu, Dong L.; Ruzmaikin, Alexander; Fontenla, Juan

2018-05-01

As an extension of Lee et al. (2013), solar cycle variation of carbon monoxide (CO) is analyzed with MLS observation, which covers more than thirteen years (2004-2017) including maximum of solar cycle 24. Being produced primarily by the carbon dioxide (CO2) photolysis in the lower thermosphere, the variations of the mesospheric CO concentration are largely driven by the solar cycle modulated ultraviolet (UV) variation. This solar signal extends down to the lower altitudes by the dynamical descent in the winter polar vortex, showing a time lag that is consistent with the average descent velocity. To characterize a global distribution of the solar impact, MLS CO is correlated with the SORCE measured total solar irradiance (TSI) and UV. As high as 0.8 in most of the polar mesosphere, the linear correlation coefficients between CO and UV/TSI are more robust than those found in the previous work. The photochemical contribution explains most (68%) of the total variance of CO while the dynamical contribution accounts for 21% of the total variance at upper mesosphere. The photochemistry driven CO anomaly signal is extended in the tropics by vertical mixing. The solar cycle signal in CO is further examined with the Whole Atmosphere Community Climate Model (WACCM) 3.5 simulation by implementing two different modeled Spectral Solar Irradiances (SSIs): SRPM 2012 and NRLSSI. The model simulations underestimate the mean CO amount and solar cycle variations of CO, by a factor of 3, compared to those obtained from MLS observation. Different inputs of the solar spectrum have small impacts on CO variation.

On the origin of the mesospheric quasi-stationary planetary waves in the unusual Arctic winter 2015/2016

NASA Astrophysics Data System (ADS)

Matthias, Vivien; Ern, Manfred

2018-04-01

The midwinter 2015/2016 was characterized by an unusually strong polar night jet (PNJ) and extraordinarily large stationary planetary wave (SPW) amplitudes in the subtropical mesosphere. The aim of this study is, therefore, to find the origin of these mesospheric SPWs in the midwinter 2015/2016 study period. The study duration is split into two periods: the first period runs from late December 2015 until early January 2016 (Period I), and the second period from early January until mid-January 2016 (Period II). While the SPW 1 dominates in the subtropical mesosphere in Period I, it is the SPW 2 that dominates in Period II. There are three possibilities explaining how SPWs can occur in the mesosphere: (1) they propagate upward from the stratosphere, (2) they are generated in situ by longitudinally variable gravity wave (GW) drag, or (3) they are generated in situ by barotropic and/or baroclinic instabilities. Using global satellite observations from the Microwave Limb Sounder (MLS) and the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) the origin of the mesospheric SPWs is investigated for both time periods. We find that due to the strong PNJ the SPWs were not able to propagate upward into the mesosphere northward of 50° N but were deflected upward and equatorward into the subtropical mesosphere. We show that the SPWs observed in the subtropical mesosphere are the same SPWs as in the mid-latitudinal stratosphere. Simultaneously, we find evidence that the mesospheric SPWs in polar latitudes were generated in situ by longitudinally variable GW drag and that there is a mixture of in situ generation by longitudinally variable GW drag and by instabilities at mid-latitudes. Our results, based on observations, show that the abovementioned three mechanisms can act at the same time which confirms earlier model studies. Additionally, the possible contribution from, or impact of, unusually strong SPWs in the subtropical mesosphere to the disruption of

Solar cycle and long term variations of mesospheric ice layers

NASA Astrophysics Data System (ADS)

Lübken, Franz-Josef; Berger, Uwe; Kiliani, Johannes; Baumgarten, Gerd; Fiedler, Jens; Gerding, Michael

2010-05-01

Ice layers in the summer mesosphere at middle and polar latitudes, frequently called `noctilucent clouds' (NLC) or `polar mesosphere clouds'(PMC), are considered to be sensitive indicators of long term changes in the middle atmosphere. We present a summary of long term observations from the ground and from satellites and compare with results from the LIMA model (Leibniz Institute Middle Atmosphere Model). LIMA 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. A strong correlation between temperatures and PMC altitudes is observed. Applied to historical measurements this give s negligible temperature trends at PMC altitudes (approximately 0.01-0.02 K/y). Trace gas concentrations are kept constant in LIMA except for water vapor which is modified by variable solar radiation. Still, long term trends in temperatures and ice layer parameters are observed, consistent with observations. As will be shown, these trends originate in the stratosphere. Solar cycle effects are expected in ice layers due to variations in background temperatures and water paper. We will present results from LIMA regarding solar cycle variations and compare with NLC observations at our lidar stations in Kühlungsborn (54°N) and ALOMAR (69°N), and also with satellite measurements.

Consequences of Recent Southern Hemisphere Winter Variability on Polar Mesospheric Clouds

DTIC Science & Technology

2011-01-01

summer latitudes. Recent observations of a link between the QBO and inter-hemispheric coupling (Espy et al., 2011) are also consistent with these...The role of the QBO in the inter-hemispheric coupling of summer mesospheric tempera- tures. Atmospheric Chemistry and Physics. 11, 495–502. Fiedler, J

SMM mesospheric ozone measurements

NASA Technical Reports Server (NTRS)

Aikin, A. C.

1990-01-01

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

The subtropical mesospheric jet observed by the Nimbus 7 Limb Infrared Monitor of the Stratosphere

NASA Technical Reports Server (NTRS)

Dunkerton, T. J.; Delisi, D. P.

1985-01-01

Nimbus 7 Limb Infrared Monitor of the Stratosphere observations of wave-mean flow interactions in the winter 1978-1979 middle atmosphere are surveyed, extending up to 0.05 mbar. These observations describe the evolution of the subtropical mesospheric jet and its polar mixed layer. Quasi-steady mean wind patterns are disrupted by three transitions in this winter: one primarily affecting the mesosphere (December 15, 1978), a minor warming affecting both regions (January 26-February 8, 1979), and a major warming largely confined to the stratosphere (February 22, 1979). The zonally averaged flow is barotropically unstable in the wings of the subtropical mesospheric jet. All the major decelerations of the mean flow are correlated with D(F), the body force per unit mass directly attributable to planetary Rossby waves, indicating that these waves make a significant contribution to the momentum budget in the lower half of the mesosphere.

The Aeronomy of Ice in the Mesosphere (AIM) mission: Overview and early science results

NASA Astrophysics Data System (ADS)

Russell, James M., III; Bailey, Scott M.; Gordley, Larry L.; Rusch, David W.; Horányi, Mihály; Hervig, Mark E.; Thomas, Gary E.; Randall, Cora E.; Siskind, David E.; Stevens, Michael H.; Summers, Michael E.; Taylor, Michael J.; Englert, Christoph R.; Espy, Patrick J.; McClintock, William E.; Merkel, Aimee W.

2009-03-01

The Aeronomy of Ice in the Mesosphere (AIM) mission was launched from Vandenberg Air Force Base in California at 1:26:03 PDT on April 25, 2007 becoming the first satellite mission dedicated to the study of polar mesospheric clouds. A Pegasus XL rocket launched the satellite into a near perfectly circular 600 km sun synchronous orbit. AIM carries three instruments selected because of their ability to provide key measurements needed to address the AIM goal which is to determine why these clouds form and vary. The instrument payload includes a nadir imager, a solar occultation instrument and an in-situ cosmic dust detector. Detailed descriptions of the science, instruments and observation scenario are presented. Early science results from the first northern and southern hemisphere seasons show a highly variable cloud morphology, clouds that are ten times brighter than measured by previous space-based instruments, and complex features that are reminiscent of tropospheric weather phenomena. The observations also confirm a previously theorized but never before directly observed population of small ice particles in the altitude region above the main Polar Mesospheric Cloud (PMC) layer that are widely believed to be the indirect cause of summertime radar echoes.

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.

Universal power law of the gravity wave manifestation in the AIM CIPS polar mesospheric cloud images

NASA Astrophysics Data System (ADS)

Rong, Pingping; Yue, Jia; Russell, James M., III; Siskind, David E.; Randall, Cora E.

2018-01-01

We aim to extract a universal law that governs the gravity wave manifestation in polar mesospheric clouds (PMCs). Gravity wave morphology and the clarity level of display vary throughout the wave population manifested by the PMC albedo data. Higher clarity refers to more distinct exhibition of the features, which often correspond to larger variances and a better-organized nature. A gravity wave tracking algorithm based on the continuous Morlet wavelet transform is applied to the PMC albedo data at 83 km altitude taken by the Aeronomy of Ice in the Mesosphere (AIM) Cloud Imaging and Particle Size (CIPS) instrument to obtain a large ensemble of the gravity wave detections. The horizontal wavelengths in the range of ˜ 20-60 km are the focus of the study. It shows that the albedo (wave) power statistically increases as the background gets brighter. We resample the wave detections to conform to a normal distribution to examine the wave morphology and display clarity beyond the cloud brightness impact. Sample cases are selected at the two tails and the peak of the normal distribution to represent the full set of wave detections. For these cases the albedo power spectra follow exponential decay toward smaller scales. The high-albedo-power category has the most rapid decay (i.e., exponent = -3.2) and corresponds to the most distinct wave display. The wave display becomes increasingly blurrier for the medium- and low-power categories, which hold the monotonically decreasing spectral exponents of -2.9 and -2.5, respectively. The majority of waves are straight waves whose clarity levels can collapse between the different brightness levels, but in the brighter background the wave signatures seem to exhibit mildly turbulent-like behavior.

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.

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

NASA Astrophysics Data System (ADS)

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

2016-12-01

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

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

NASA Astrophysics Data System (ADS)

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

2009-12-01

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

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.

The Aeronomy of Ice in the Mesosphere Mission: Science Results After Three PMC Seasons

NASA Astrophysics Data System (ADS)

Russell, J. M.; Bailey, S. M.; Rusch, D.; Thomas, G. E.; Gordley, L. L.; Hervig, M. E.; Horanyi, M.

2008-12-01

The Aeronomy of Ice in the Mesosphere (AIM) satellite was launched from Vandenberg Air Force Base in California at 1:26:03 PDT on April 25, 2007 becoming the first satellite mission dedicated to the study of Polar Mesospheric Clouds (PMCs). A Pegasus XL rocket launched the satellite into a near perfect 600 km sun synchronous circular orbit. AIM carries three instruments - a nadir imager, a solar occultation sounder and an in-situ cosmic dust detector. Brief instrument descriptions, data quality and key science results will be presented. AIM has observed three PMC seasons at this point in time including two in the northern hemisphere (2007 and 2008) and one in the south (2007/2008). The observations are providing extraordinary detail on the horizontal and vertical extent of PMCs and their variability. Results show that the mesospheric ice layer extends up to the mesopause, there are voids in the PMC fields of both hemispheres and for the two northern seasons, temporal trends are remarkably similar.

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

NASA Astrophysics Data System (ADS)

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

2017-09-01

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

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

NASA Technical Reports Server (NTRS)

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

2017-01-01

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

Prospects for detecting a net photon circular polarization produced by decaying dark matter

NASA Astrophysics Data System (ADS)

Elagin, Andrey; Kumar, Jason; Sandick, Pearl; Teng, Fei

2017-11-01

If dark matter interactions with Standard Model particles are C P violating, then dark matter annihilation/decay can produce photons with a net circular polarization. We consider the prospects for experimentally detecting evidence for such a circular polarization. We identify optimal models for dark matter interactions with the Standard Model, from the point of view of detectability of the net polarization, for the case of either symmetric or asymmetric dark matter. We find that, for symmetric dark matter, evidence for net polarization could be found by a search of the Galactic center by an instrument sensitive to circular polarization with an efficiency-weighted exposure of at least 50 ,000 cm2 yr , provided the systematic detector uncertainties are constrained at the 1% level. Better sensitivity can be obtained in the case of asymmetric dark matter. We discuss the prospects for achieving the needed level of performance using possible detector technologies.

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

NASA Astrophysics Data System (ADS)

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

2016-12-01

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

Mesospheric Ice particle sizes derived from two-color SME (1982-1986) and SNOE (1998- 2002) UV satellite measurements

NASA Astrophysics Data System (ADS)

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

2006-12-01

The UV spectrum of scattering from mesospheric ice particles (Polar Mesospheric Clouds) contains information on particle size, and on the microphysics of the cold summertime mesopause region. Nearly identical Ultraviolet Spectrometers were flown on both the Solar Mesosphere Explorer (SME) and Student Nitric Oxide Explorer (SNOE) satellites, both in sun-synchronous orbits reaching deep within the cold polar regions where PMC occur. The instruments measured two wavelengths simultaneously (265 and 296 nm for SME, 215 and 237 nm for SNOE), and detected PMC over a grand total of twenty PMC seasons, each covering five year periods (1982-1986 for SME) and (1998-2002 for SNOE). Using the well well-known wavelength dependence of Rayleigh scattering from thje cloud-free mesosphere we calibrate the two channels with respect to each other . The resulting accurate color ratios are then analyzed taking the brightness of the clouds into account, etc. Previous studies of the available spectral data (Rapp et al., 2006) suggested that non-spherical particles of large aspect ratios are required for consistency with the data then available. We test their results on a much more extensive data set for a large number of PMC seasons. Through the use of modern scattering theory, and predictions of the size distribution from microphysical models, such as the CARMA model, we report particle size and shape regimes which are consistent with the color ratios, obtained with different scattering geometries in both northern and southern hemispheres.

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

NASA Astrophysics Data System (ADS)

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

2017-01-01

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

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

NASA Astrophysics Data System (ADS)

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

2017-09-01

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

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

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.

The ASSET intercomparison of stratosphere and lower mesosphere humidity analyses

NASA Astrophysics Data System (ADS)

Thornton, H. E.; Jackson, D. R.; Bekki, S.; Bormann, N.; Errera, Q.; Geer, A. J.; Lahoz, W. A.; Rharmili, S.

2008-07-01

This paper presents results from the first detailed intercomparison of stratosphere-lower mesosphere water vapour analyses; it builds on earlier results from the "Assimilation of ENVISAT Data" (ASSET) project. With the availability of high resolution, good quality Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) water vapour profiles, the ability of four different atmospheric models to assimilate these data is tested. MIPAS data have been assimilated over September 2003 into the models of the European Centre for Medium Range Weather Forecasts (ECMWF), the Belgian Institute for Space and Aeronomy (BIRA-IASB), the French Service d'Aéronomie (SA-IPSL) and the UK Met Office. The resultant middle atmosphere humidity analyses are compared against independent satellite data from the Halogen Occultation Experiment (HALOE), the Polar Ozone and Aerosol Measurement (POAM III) and the Stratospheric Aerosol and Gas Experiment (SAGE II). The MIPAS water vapour profiles are generally well assimilated in the ECMWF, BIRA-IASB and SA systems, producing stratosphere-mesosphere water vapour fields where the main features compare favourably with the independent observations. However, the models are less capable of assimilating the MIPAS data where water vapour values are locally extreme or in regions of strong humidity gradients, such as the Southern Hemisphere lower stratosphere polar vortex. Differences in the analyses can be attributed to the choice of humidity control variable, how the background error covariance matrix is generated, the model resolution and its complexity, the degree of quality control of the observations and the use of observations near the model boundaries. Due to the poor performance of the Met Office analyses the results are not included in the intercomparison, but are discussed separately. The Met Office results highlight the pitfalls in humidity assimilation, and provide lessons that should be learnt by developers of stratospheric humidity

Characterization of a Double Mesospheric Bore Over Europe

NASA Astrophysics Data System (ADS)

Smith, Steven M.; Stober, Gunter; Jacobi, Christoph; Chau, Jorge L.; Gerding, Michael; Mlynczak, Martin G.; Russell, James M.; Baumgardner, Jeffrey L.; Mendillo, Michael; Lazzarin, Monica; Umbriaco, Gabriel

2017-09-01

Observations of a pair of mesospheric bore disturbances that propagated through the nighttime mesosphere over Europe are presented. The observations were made at the Padua Observatory, Asiago (45.9°N, 11.5°E), by the Boston University all-sky imager on 11 March 2013. The bores appeared over the northwest horizon, approximately 30 min apart, and propagated toward the southeast. Using additional satellite and radar data, we present evidence indicating the bores originated in the mesosphere from a single, larger-scale mesospheric disturbance propagating through the mesopause region. Furthermore, the large-scale mesospheric disturbance appeared to be associated with an intense weather disturbance that moved southeastward over the United Kingdom and western Europe during 10 and 11 March.

Remote sensing of mesospheric electric fields using MF radars

NASA Astrophysics Data System (ADS)

Meek, C. E.; Manson, A. H.; Martynenko, S. I.; Rozumenko, V. T.; Tyrnov, O. F.

2004-07-01

Large mesospheric electric fields can play an essential role in middle atmospheric electrodynamics (see, e.g., Goldberg, R. A., Middle Atmospheric Electrodynamics during MAP, Adv. Space Res. 10 (10) (1990) 209). The V/m electric fields of atmospheric origin can be the possible cause of large variations in the electron collision frequency at mesospheric altitudes, and this provides a unique opportunity to take measurements of electric fields in the lower ionosphere by using remote sensing instruments employing radiowave techniques. A technique has been proposed for making estimates of large mesospheric electric field intensities on the lower edge of the ionosphere by using MF radar data and the inherent effective electron collision frequency. To do this, data collected in Canada and Ukraine were utilized. The developed technique permits the changes in mesospheric electric field intensities to be derived from MF radar data in real time. The statistical analysis of data consistent with large mesospheric electric field intensities in the 60-67km region resulted in the following inferences. There are at least two mechanisms for the generation of large mesospheric electric fields in the mesosphere. The most likely mechanism, with a probability of 60-70%, is the summation of random fields from a large number of elementary small-scale mesospheric generators, which results in a one-parameter Rayleigh distribution of the total large mesospheric electric field intensity E with a mean value of approximately 0.7-0.9V/m in the 60-67km altitude region, or in the corresponding one-parameter exponential distribution of the intensity squared E2 of large mesospheric electric fields. The second mechanism of unknown nature, with 5-15% probability, gives rise to the sporadic appearance of large mesospheric electric field intensities E>2.5V/m with a mean of 4V/m. Statistically significant seasonal differences in the averaged large mesospheric electric field parameters have not been

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

NASA Astrophysics Data System (ADS)

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

2017-09-01

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

The PMC-Turbo Balloon Mission to Study Gravity Waves and Turbulence through High-Resolution Imaging of Polar Mesospheric Clouds

NASA Astrophysics Data System (ADS)

Williams, B. P.; Kjellstrand, B.; Jones, G.; Reimuller, J. D.; Fritts, D. C.; Miller, A.; Geach, C.; Limon, M.; Hanany, S.; Kaifler, B.; Wang, L.; Taylor, M. J.

2017-12-01

PMC-Turbo is a NASA long-duration, high-altitude balloon mission that will deploy 7 high-resolution cameras to image polar mesospheric clouds (PMC) and measure gravity wave breakdown and turbulence. The mission has been enhanced by the addition of the DLR Balloon Lidar Experiment (BOLIDE) and an OH imager from Utah State University. This instrument suite will provide high horizontal and vertical resolution of the wave-modified PMC structure along a several thousand kilometer flight track. We have requested a flight from Kiruna, Sweden to Canada in June 2017 or McMurdo Base, Antarctica in Dec 2017. Three of the PMC camera systems were deployed on an aircraft and two tomographic ground sites for the High Level campaign in Canada in June/July 2017. On several nights the cameras observed PMC's with strong gravity wave breaking signatures. One PMC camera will piggyback on the Super Tiger mission scheduled to be launched in Dec 2017 from McMurdo, so we will obtain PMC images and wave/turbulence data from both the northern and southern hemispheres.

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

Vorticity and Λ polarization in baryon rich matter

NASA Astrophysics Data System (ADS)

Baznat, Mircea; Gudima, Konstantin; Prokhorov, George; Sorin, Alexander; Teryaev, Oleg; Zakharov, Valentin

2018-02-01

The polarization of Λ hyperons due to axial chiral vortical effect is discussed. The effect is proportional to (strange) chemical potential and is pronounced at lower energies in baryon-rich matter. The polarization of ¯ has the same sihn and larger magnitude. The emergence of vortical structures is observed in kinetic QGSM models. The hydrodynamical helicity separation receives the contribution of longitudinal velocity and vorticity implying the quadrupole structure of the latter. The transition from the quark vortical effects to baryons in confined phase may be achieved by exploring the axial charge. At the hadronic level the polarization corresponds to the cores of quantized vortices in pionic superfluid. The chiral vortical effects may be also studied in the frmework of Wigner function establishing the relation to the thermodynamical approach to polarization.

Formation of Mesospheric Clouds on Mars

NASA Astrophysics Data System (ADS)

Plane, J. M. C.; Audouard, J.; Listowski, C.; Mangan, T.; Maattanen, A. E.; Montmessin, F.; Forget, F.; Millour, E.; Spiga, A.; Crismani, M. M. J.; Schneider, N. M.

2017-12-01

Martian Mesospheric Clouds (MMCs) are observed intermittently in the Martian atmosphere between 60 and 100 km, occurring particularly at low latitudes. The clouds consist mainly of CO2-ice particles around 1 mm in radius. Explaining the nucleation and growth of these particles is challenging: it has been assumed that - by analogy with polar mesospheric clouds in the terrestrial atmosphere - nucleation occurs on meteoric smoke particles (very small metal-silicate particles resulting from the condensation of the vapor produced by cosmic dust ablation). Indeed, 1D modeling of CO2 microphysics suggests that an exogenous source of nuclei is necessary to model CO2 MMCs, in agreement with observations in cold pockets produced by the coupling of gravity waves and thermal tides. However, a recent laboratory study has shown that smoke particles, which would be around 1 nm in size - require extremely high CO2 supersaturations to nucleate CO2 ice. Here we present an alternative picture of the nucleation of CO2-ice particles. The major meteoric metals - Mg and Fe - should form MgCO3 and FeCO3 molecules in the Mars atmosphere below 90 km. These molecules have enormous electric dipole moments (11.6 and 9.3 Debye, respectively), and so will immediately form stable clusters with 3 CO2 molecules, which then slowly exchange with H2O to produce hexa-hydrated carbonate molecules. These primary particles polymerize readily to form a background population of "dirty" water-ice particles. Using MAVEN-IUVS measurements of the background Mg+ ion layer to constrain the injection rates of Mg and Fe from meteoric ablation, and a 1D model of metal chemistry coupled to an aerosol coagulation model, we show that the population of these water-ice particles with radii greater than 10 nm should be around 200 cm-3 at 80 km, thus providing a population of effective CO2-ice nuclei. When these nuclei are input in the Laboratoire de Météorologie Dynamique (LMD) Mars GCM, first results show that they can

The ASSET intercomparison of stratosphere and lower mesosphere humidity analyses

NASA Astrophysics Data System (ADS)

Thornton, H. E.; Jackson, D. R.; Bekki, S.; Bormann, N.; Errera, Q.; Geer, A. J.; Lahoz, W. A.; Rharmili, S.

2009-02-01

This paper presents results from the first detailed intercomparison of stratosphere-lower mesosphere water vapour analyses; it builds on earlier results from the EU funded framework V "Assimilation of ENVISAT Data" (ASSET) project. Stratospheric water vapour plays an important role in many key atmospheric processes and therefore an improved understanding of its daily variability is desirable. With the availability of high resolution, good quality Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) water vapour profiles, the ability of four different atmospheric models to assimilate these data is tested. MIPAS data have been assimilated over September 2003 into the models of the European Centre for Medium Range Weather Forecasts (ECMWF), the Belgian Institute for Space and Aeronomy (BIRA-IASB), the French Service d'Aéronomie (SA-IPSL) and the UK Met Office. The resultant middle atmosphere humidity analyses are compared against independent satellite data from the Halogen Occultation Experiment (HALOE), the Polar Ozone and Aerosol Measurement (POAM III) and the Stratospheric Aerosol and Gas Experiment (SAGE II). The MIPAS water vapour profiles are generally well assimilated in the ECMWF, BIRA-IASB and SA systems, producing stratosphere-mesosphere water vapour fields where the main features compare favourably with the independent observations. However, the models are less capable of assimilating the MIPAS data where water vapour values are locally extreme or in regions of strong humidity gradients, such as the southern hemisphere lower stratosphere polar vortex. Differences in the analyses can be attributed to the choice of humidity control variable, how the background error covariance matrix is generated, the model resolution and its complexity, the degree of quality control of the observations and the use of observations near the model boundaries. Due to the poor performance of the Met Office analyses the results are not included in the intercomparison

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

NASA Astrophysics Data System (ADS)

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

2016-12-01

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

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.

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

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

NASA Astrophysics Data System (ADS)

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

2009-11-01

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

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

NASA Astrophysics Data System (ADS)

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

2009-01-01

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

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

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.

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.

Improved spatial and temporal characteristics of ionospheric irregularities and polar mesospheric summer echoes using coherent MIMO and aperture synthesis radar imaging

NASA Astrophysics Data System (ADS)

Chau, J. L.; Urco, J. M.; Milla, M. A.; Vierinen, J.

2017-12-01

We have recently implemented Multiple-input multiple-output (MIMO) radar techniques to resolve temporal and spatial ambiguities of ionospheric and atmospheric irregularities, with improve capabilities than previously experiments using single-input multi-output (SIMO) techniques. SIMO techniques in the atmospheric and ionospheric coherent scatter radar field are usually called aperture synthesis radar imaging. Our implementations have done at the Jicamarca Radio Observatory (JRO) in Lima, Peru, and at the Middle Atmosphere Alomar Radar System (MAARSY) in Andenes, Norway, to study equatorial electrojet (EEJ) field-aligned irregularities and polar mesospheric summer echoes (PMSE), respectively. Figure 1 shows an example of a configuration used at MAARSY and the comparison between the SIMO and MIMO resulting antenna point spread functions, respectively. Although in this work we present the details of the implementations at each facility, we will focus on the observed peculiarities of each phenomenon, making emphasis in the underlying physical mechanisms that govern their existence and their spatial and temporal modulation. For example, what are the typical horizontal scales of PMSE variability in both intensity and wind field?

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.

Latitudinal and interhemispheric variation of stratospheric effects on mesospheric ice layer trends

NASA Astrophysics Data System (ADS)

Lübken, F.-J.; Berger, U.

2011-02-01

Latitudinal and interhemispheric differences of model results on trends in mesospheric ice layers and background conditions are analyzed. The model nudges to European Centre for Medium-Range Weather Forecasts data below ˜45 km. Greenhouse gas concentrations in the mesosphere are kept constant. Temperature trends in the mesosphere mainly come from shrinking of the stratosphere and from dynamical effects. Water vapor increases at noctilucent cloud (NLC) heights and decreases above due to increased freeze drying caused by temperature trends. There is no tendency for ice clouds in the Northern Hemisphere for extending farther southward with time. Trends of NLC albedo are similar to satellite measurements, but only if a time period longer than observations is considered. Ice cloud trends get smaller if albedo thresholds relevant to satellite instruments are applied, in particular at high polar latitudes. This implies that weak and moderate NLC is favored when background conditions improve for NLC formation, whereas strong NLC benefits less. Trends of ice cloud parameters are generally smaller in the Southern Hemisphere (SH) compared to the Northern Hemisphere (NH), consistent with observations. Trends in background conditions have counteracting effects on NLC: temperature trends would suggest stronger ice increase in the SH, and water vapor trends would suggest a weaker increase. 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. Trends of NLC brightness and occurrence rates decrease with decreasing latitude in both hemispheres. The latitudinal variation of these trends is primarily determined by induced water vapor trends. Trends in NLC altitudes are generally small. Stratospheric temperature trends vary

Synthesis and characterization of drug loaded albumin mesospheres for intratumoral chemotherapy

NASA Astrophysics Data System (ADS)

Freeman, Shema Taian

Conventional chemotherapy is problematic due to toxic complications. Intratumoral (IT) drug delivery, offers a new, less toxic, potentially more effective treatment concept. The objectives of this research encompassed (1) an investigation of the synthesis of BSA mesospheres (MS) employing genipin (GEN) as a novel crosslinking agent, (2) comparison with glutaraldehyde (GTA) crosslinked mesosphere, (3) a study of process parameters to define conditions for the synthesis of 1-10microm drug loaded mesospheres, and (4) investigation of the drug delivery properties of such mesospheres for IT chemotherapy. Smooth, spherical BSA-MS, crosslinked with glutaraldehyde and genipin, were prepared in a dry particle size range of 1microm to 10microm. It was shown that increasing dispersion stirring rate, crosslinking time and GEN/BSA ratio led to a decrease in particle size and a narrower particle distribution. It was also shown that increasing crosslinking time, GEN/BSA ratio, BSA concentrations, GEN concentration slowed enzymatic degradation. Post-loading and in situ drug loading methods were studied for the incorporation of cyclophosphamide and cisplatin into mesospheres. Maximum post loading of cisplatin was 3.2% (w/w) and 2.6% (w/w) with GEN and with GTA crosslinking. For cyclophosphamide 8.2% (w/w) and 7.1% (w/w) loading was achieved with GEN and GTA respectively. In situ drug loaded MS genipin and glutaraldehyde crosslinked mesospheres were also synthesized with 1.8% (w/w) cisplatin (using GEN) and 1.2% (w/w) (using GTA). Maximum loading of 13.3% (w/w) was achieved for cyclophosphamide in genipin crosslinked mesospheres. The cytotoxicity of in situ loaded genipin and glutaraldehyde crosslinked cisplatin mesospheres was evaluated using a murine Lewis lung model. Both genipin and glutaraldehyde crosslinked BSA-cisplatin mesospheres proved to be cytotoxic during a 48 hour test. Ultimately a standard set of processing parameters (BSA concentration, CAB concentration, GEN

Tracing the Inter-Hemispheric Coupling During Polar Summer Periods of 2002-2010 Using TIMED/SABER Measurements

NASA Technical Reports Server (NTRS)

Goldberg, Richard; Feoflow, Artem; Pesnell, Dean; Kutepov, Alexander

2010-01-01

It has been found that for more than one polar summer season between 2002-2010, the northern polar mesospheric region near and above the mesospheric maximum was warmer than normal. The strongest warming effect of this type was observed to occur during northern summer 2002. Theoretical studies have implied that these "anomalies" were preceded by unusual dynamical processes occurring in the southern hemisphere. We have analyzed temperature distributions measured by the SABER limb scanning infrared radiometer aboard the NASA TIMED satellite between 2002-2010 at altitudes from 15 to 110 km and for latitudes between 83 deg. S to 83 deg. N. We describe the approach to trace the inter-hemispheric temperature correlatoins and to identify the global features that were unique for the "anomalous" northern polar summers.

Mesospheric turbulence and related parameters over the low latitude region

NASA Astrophysics Data System (ADS)

Chakravarty, S.; Datta, J.; Kamala, S.; Gupta, S.

Recently a number of studies have been carried out primarily by using ground based radar techniques to understand the phenomena of wave dynamics and turbulence in the mesosphere. While such studies have covered the middle and high latitude region quite well there is a lack of such data for the low latitude region. Extensive studies using MST radar conducted from middle and high latitude stations have resulted in providing a clear picture of the mesospheric dynamics and related structures (? n) responsible for radar backscattered echoes from mesosphere. The experiments have also enabled determination of various turbulence related parameters such as e , , LB, uz etc. A major discovery in this region is the, occurrence of PMSE layers in the mesopause regions which considerably enhances the SNR of radar return power. Only in recent times MST radar systems have been set up over the low latitude region even though the technique itself was first demonstrated at equatorial station Jicamarca using the available incoherent backscatter radar. Using these facilities broad characteristics of the turbulence structures in the mesosphere have been brought out showing similarities and differences of such results when compared with middle and high latitude stations. In all these observations it has not been possible to characterise the mesospheric turbulence with respect to the energy spectrum and its micro structure. Rocket measurements have been carried out to study the ionization parameters such as electron density irregularities in the mesosphere ( Ne) either independently or? simultaneously with MST radar observations wherever possible. Some consistency has been noticed in the occurrence of ? Ne and simultaneous radar return echo power from the height range of these irregularities. The main aim of this paper is to analyse the existing results on mesospheric dynamics and turbulence with the associated modulation in mesospheric ionization from sounding rockets launched from

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.

Global variability of mesospheric temperature: Mean temperature field

NASA Astrophysics Data System (ADS)

Shepherd, Marianna G.; Evans, Wayne F. J.; Hernandez, G.; Offermann, Dirk; Takahashi, Hisao

2004-12-01

Daytime zonally (longitudinally) averaged temperatures from the Wind Imaging Interferometer (WINDII) on the Upper Atmosphere Research Satellite (UARS) and nightly temperatures from various ground-based hydroxyl airglow observations are employed in the study of the global and seasonal variability of the upper mesospheric temperature field. The study examines the latitudinal variability of the annual cycle of mesospheric temperature at 75, 82, and 87 km employing 7 years (1991-1997) of WINDII mesospheric temperature data at latitudes from 20°S to 65°N at 75 km, 35°S to 65°N at 82 km, and from 45°S to 65°N at 87 km height. Particular attention is given to the latitude region of ±40° around the equator. Harmonic analysis of the 7-year temperature time series reveals the presence of a dominant annual, ˜90- and 60-day oscillations at high northern latitudes and a strong semiannual oscillation (SAO) at equatorial and tropical latitudes. A quasi-biennial oscillation (QBO) is also identified extending from 45°S to 65°N. At 75 km the SAO is manifested as minima in the temperature composites at spring and fall equinox and maxima at winter and summer solstice; at 87 km the SAO is out of phase with respect to the 75-km SAO, with maxima at equinox and minima around the solstice periods. The phase reversal takes place around 82 km and is associated with a mesospheric temperature inversion between 77 and 86 km height. Accounting for tidal contribution by adopting tidal predictions by the Extended Canadian Middle Atmosphere Model (CMAM) shows that a strong temperature decrease (˜35 K) seen during the 1993 March equinox at equatorial and tropical latitudes is not associated with solar migrating tides. WINDII global climatology derived at 75, 82, and 87 km revealed mesospheric SAO asymmetry with a stronger September equinox and interhemispheric asymmetry with a quieter and colder southern hemisphere. Comparisons with independent ground-based observations and the Solar

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).

Secondary Gravity Waves in the Winter Mesosphere: Results From a High-Resolution Global Circulation Model

NASA Astrophysics Data System (ADS)

Becker, Erich; Vadas, Sharon L.

2018-03-01

This study analyzes a new high-resolution general circulation model with regard to secondary gravity waves in the mesosphere during austral winter. The model resolves gravity waves down to horizontal and vertical wavelengths of 165 and 1.5 km, respectively. The resolved mean wave drag agrees well with that from a conventional model with parameterized gravity waves up to the midmesosphere in winter and up to the upper mesosphere in summer. About half of the zonal-mean vertical flux of westward momentum in the southern winter stratosphere is due to orographic gravity waves. The high intermittency of the primary orographic gravity waves gives rise to secondary waves that result in a substantial eastward drag in the winter mesopause region. This induces an additional eastward maximum of the mean zonal wind at z ˜ 100 km. Radar and lidar measurements at polar latitudes and results from other high-resolution global models are consistent with this finding. Hence, secondary gravity waves may play a significant role in the general circulation of the winter mesopause region.

Thermosphere-Ionosphere-Mesosphere Modeling Using the TIME-GCM

DTIC Science & Technology

2014-09-30

respectively. The CCM3 is the NCAR Community Climate Model, Version 3.6, a GCM of the troposphere and stratosphere. All models include self-consistent...middle atmosphere version of the NCAR Community Climate Model, (2) the NCAR TIME-GCM, and (3) the Model for Ozone and Related Chemical Tracers (MOZART... troposphere , but the impacts of such events extend well into the mesosphere. The coupled NCAR thermosphere-ionosphere-mesosphere- electrodynamics general

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

NASA Astrophysics Data System (ADS)

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

2015-07-01

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.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

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.

Global simulations and observations of O(1S), O2(1Σ) and OH mesospheric nightglow emissions

NASA Astrophysics Data System (ADS)

Yee, Jeng-Hwa; Crowley, G.; Roble, R. G.; Skinner, W. R.; Burrage, M. D.; Hays, P. B.

1997-09-01

Despite a large number of observations of mesospheric nightglow emissions in the past, the quantitative comparison between theoretical and experimental brightnesses is rather poor, owing primarily to the short duration of the observations, the strong variability of the tides, and the influence of short-timescale gravity waves. The high-resolution Doppler imager (HRDI) instrument onboard the upper atmosphere research satellite (UARS) provides nearly simultaneous, near-global observations of O(1S) green line, O2(0-1) atmospheric band, and OH Meinel band nightglow emissions. Three days of these observations near the September equinox of 1993 are presented to show the general characteristics of the three emissions, including the emission brightness, peak emission altitude, and their temporal and spatial variabilities. The global distribution of these emissions is simulated on the basis of atmospheric parameters from the recently developed National Center for Atmospheric Research (NCAR) thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (TIME-GCM). The most striking features revealed by the global simulation are the structuring of the mesospheric nightglow by the diurnal tides and enhancements of the airglow at high latitudes. The model reproduces the inverse relationship observed by HRDI between the nightglow brightness and peak emission altitude. Analysis of our model results shows that the large-scale latitudinal/tidal nightglow brightness variations are a direct result of a complex interplay between mesospheric and lower thermospheric diffusive and advective processes, acting mainly on the atomic oxygen concentrations. The inclination of the UARS spacecraft precluded observations of high latitude nightglow emissions by HRDI. However, our predicted high-latitude brightness enhancements confirm previous limited groundbased observations in the polar region. This work provides an initial validation of the NCAR-TIMEGCM using airglow data.

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.

The Polar Mesopause Sulfate Aerosol Layer

NASA Astrophysics Data System (ADS)

Mills, M. J.; Toon, O. B.; Thomas, G.; Solomon, S.

2001-05-01

Noctilucent ("night-luminous") clouds (NLC), or as seen from space, Polar Mesospheric Clouds (PMC), are typically 1 to 2 km thick and located at altitudes of 80 to 85 km, where the temperature is near 150K. NLC generally occur between 50 degrees latitude to the pole from May to August in the Northern Hemisphere, with occasional sightings at lower latitudes. An extraordinary low-latitude sighting occurred on June 21, 1999 at 41oN. Direct evidence that PMC are composed of water ice was recently reported from satellite observations made in the near infrared. The formation of ice clouds in the upper atmosphere has been studied extensively as a result of the role of Polar Stratospheric Clouds (PSC) in polar ozone depletion. There exists ample evidence that preexisting stratospheric liquid sulfate aerosol plays an important role in the formation of solid PSC particles. Until recent laboratory measurements showed otherwise, however, it was believed that photolysis of sulfuric acid in the upper stratosphere would prevent the formation of such aerosol in the mesosphere. We present here calculations from a microphysical atmospheric model which point to sulfate from volcanic and non-volcanic sources alike as the origin of nuclei on which PMC and NLC form. Current theories have relied on meteor 'smoke' particles arising from meteor ablation and recondensation to explain the nucleation of NLC/PMC ice particles. Our calculated sizes and concentrations of high latitude summer mesosphere sulfate aerosol particles are comparable to or exceed those expected of the meteor source. The model shows that large volcanic eruptions will add significantly to this particle population, several years following the injection. The record of the number of NLC sightings in response to large volcanic eruptions is contradictory. However, microphysical models show that injections of particles may result in positive, negative or neutral response in the visual brightness of NLC, depending on sulfur

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.

'Downward control' of the mean meridional circulation and temperature distribution of the polar winter stratosphere

NASA Technical Reports Server (NTRS)

Garcia, Rolando R.; Boville, Byron A.

1994-01-01

According to the 'downward control' principle, the extratropical mean vertical velocity on a given pressure level is approximately proportional to the meridional gradient of the vertically integrated zonal force per unit mass exerted by waves above that level. In this paper, a simple numerical model that includes parameterizations of both planetary and gravity wave breaking is used to explore the influence of gravity wave breaking in the mesosphere on the mean meridional circulation and temperature distribution at lower levels in the polar winter stratosphere. The results of these calculations suggest that gravity wave drag in the mesosphere can affect the state of the polar winter stratosphere down to altitudes below 30 km. The effect is most important when planetary wave driving is relatively weak: that is, during southern winter and in early northern winter. In southern winter, downwelling weakens by a factor of 2 near the stratospause and by 20% at 30 km when gravity wave drag is not included in the calculations. As a consequence, temperatures decrease considerably throughout the polar winter stratosphere (over 20 K above 40 km and as much as 8 K at 30 km, where the effect is enhanced by the long radiative relaxation timescale). The polar winter states obtained when gravity wave drag is omitted in this simple model resemble the results of simulations with some general circulation models and suggest that some of the shortcomings of the latter may be due to a deficit in mesospheric momentum deposition by small-scale gravity waves.

Influence of Solar and Lunar Tides on the Mesopause Region as Observed in Polar Mesosphere Summer Echoes Characteristics

NASA Astrophysics Data System (ADS)

Dalin, P.; Kirkwood, S.; Pertsev, N.; Perminov, V.

2017-10-01

Long-term observations of polar mesosphere summer echoes (PMSE) from 2002 to 2012 are investigated with the aim to statistically study the effects of solar thermal migrating and lunar gravitational tides on aerosol layers and their environment at altitudes 80-90 km. The solar and lunar tidal periodicities are clearly present in PMSE data. For the first time, both amplitudes and phases of solar and lunar tides are estimated using PMSE data from the ESRAD radar located at Esrange (Sweden). The diurnal, semidiurnal, and terdiurnal solar migrating tides show pronounced periodicities in the PMSE strength and wind velocity components. Lunar tides demonstrate clear oscillations in the PMSE strength and wind velocities as well. "canonical" lunar gravitational tides, corresponding to the lunar gravitational potential, produce rather large amplitudes and are comparable to the solar thermal tides, whereas "noncanonical" lunar oscillations have minor effects on PMSE layers, but are still statistically significant. The influence of diurnal/semidiurnal tides and monthly/semimonthly tidal components is studied separately. Our estimations of solar thermal and lunar tidal amplitudes are in good agreement with those of previous model and experimental studies. A new mechanism of quadratic demodulation of the solar semidiurnal and lunar semidiurnal tides is shown to be valid at the summer mesopause and can explain periodical PMSE oscillations due to the lunar synodic semimonthly tide with period of 14.77 days. Two harmonics with periods of 27.0 and 13.5 days supposedly representing the solar rotation cycle are also clearly present in PMSE data.

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.

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.

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.

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.

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.

Mesospheric temperature trends derived from standard phase-height measurements

NASA Astrophysics Data System (ADS)

Peters, Dieter H. W.; Entzian, Günter; Keckhut, Philippe

2017-10-01

New homogeneous time series of daily standard phase-height (SPH) and daily plasma scale-height (PSH) have been derived from a 50-year long-radio-wave measurement of the broadcasting station Allouis (France, 162 kHz). The signal was received at Kühlungsborn (54°N, 12°E, Mecklenburg, Germany) and the present series is a third release. The daily time series of SPH shows in its spectrum dominant modes which are typical for the solar cycle (SC), for El Niño-Southern Oscillation (ENSO) and for quasi-biannual oscillation (QBO), indicating solar and lower atmospheric influences. Surprisingly, the time series of daily PSH shows a band of dominant cycles larger than 16 years. In order to exclude the influence of the winter anomaly in the determination of column-integrated mesospheric temperature trends the phase-height-temperature procedure is confined to summer months. The derived thickness temperature of the mesosphere decreased statistically significant over the period 1959-2008 after pre-whitening with summer mean of solar sun spot numbers. The trend value is in the order of about -1.05 K/decade if the stratopause trend is excluded. The linear regression is more pronounced, -1.35 K/decade for the period of 1963-1985 (2 SCs), but weaker, -0.51 K/decade during 1986-2008 (last 2 SCs). The linear regression is in very good agreement with a mean column-integrated mesospheric trend derived from OHP-Lidar temperatures on a monthly mean basis for the last two SCs. This clearly shows that the thickness temperature of the mesosphere derived from phase-height measurement is a useful proxy for the long-term summer temperature change in the mesosphere from 1959 until 2008.

Observed Responses of Mesospheric Water Vapor to Solar Cycle and Dynamical Forcings

NASA Astrophysics Data System (ADS)

Remsberg, Ellis; Damadeo, Robert; Natarajan, Murali; Bhatt, Praful

2018-04-01

This study focuses on responses of mesospheric water vapor (H2O) to the solar cycle flux at Lyman-α wavelength and to dynamical forcings according to the multivariate El-Nino/Southern Oscillation (ENSO) index. The zonal-averaged responses are for latitudes from 60°S to 60°N and pressure-altitudes from 0.01 to 1.0 hPa, as obtained from multiple linear regression analyses of time series of H2O from the Halogen Occultation Experiment for July 1992 to November 2005. The results compare very well with those from a separate simultaneous temporal and spatial (STS) method that also confirms that there are no significant sampling biases affecting both sets of results. Distributions of the seasonal amplitudes for temperature and H2O are in accord with the seasonal net circulation. In general, the responses of H2O to ENSO are anticorrelated with those of temperature. H2O responses to multivariate ENSO index are negative in the upper mesosphere and largest in the Northern Hemisphere; responses in the lower mesosphere are more symmetric with latitude. H2O responses to the Lyman-α flux (Lya) vary from strong negative values in the uppermost mesosphere to very weak, positive values in the tropical lowermost mesosphere. However, the effects of those H2O responses to the solar activity extend to the rest of the mesosphere via dynamical processes. Profiles of the responses to ENSO and Lya also agree reasonably with published results for H2O at the low latitudes from the Microwave Limb Sounder.

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.

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.

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

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

NASA Astrophysics Data System (ADS)

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

2016-12-01

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

The Compositions, Particle Sizes, and Distributions of Ice Aerosols in the Mars Mesosphere from 2009-2016 CRISM Visible-NearIR Limb Spectra

NASA Astrophysics Data System (ADS)

Clancy, R. T.; Smith, M. D.; Wolff, M. J.; Toigo, A. D.; Seelos, K. D.; Murchie, S. L.

2016-12-01

Since 2009, the CRISM visible-nearIR imaging spectrometer onboard the Mars Reconnaissance Orbiter (MRO) has returned over 70 orbits of Mars limb image scans over the 0-130 km altitude range. Pole-to-pole latitudinal coverage is obtained from the near-polar, sun-synchronous (LT 3pm) MRO orbit for a limited set of surface longitudes centered on Tharsis, Valles Mariners, Meridioni, and Hellas regions. Seasonal coverage extends over the full seasonal range (Ls=0-360°), as accumulated over 2009-2016 (MY 29-33), supporting a range of aerosol and airglow studies (Smith et al., 2013; Clancy et al., 2012, 2013). The 0.4-4.0 μm wavelength range of these CRISM limb observations proves particularly suitable to characterizing aerosol composition and particle sizes, particularly for the Mars mesosphere (z=50-100 km), which has only recently been observed with any dedication by MCS (Sefton-Nash et al, 2013) and CRISM limb measurements. Dust and H2O, CO2 ice aerosols are clearly distinguished by their distinct scattering and absorption behaviors over the key 2-4 μm wavelength region, and their particle sizes are well determined by the 0.4-3 μm wavelength region. Several key attributes are determined for Mars mesospheric aerosols. Dust aerosols are largely undetected, and are apparently injected to such heights only during global dust storms (Clancy et al, 2010). Ice clouds are generally common at 55-75 km altitudes, although in separate halves of the Mars year. CO2 and H2O ice clouds are most prominent during the aphelion and perihelion portions of the Mars orbit, respectively. CO2 ice clouds, which occur at low latitudes over specific surface longitudes, present distinct particle size populations ranging from 0.5 to 1.5 μm (Reff). Mesospheric H2O ice clouds exhibit somewhat smaller particle sizes (Reff=0.3-1 μm) and extend over low to mid latitudes. This orbital dependence for mesospheric ice aerosol composition indicates extreme annual (orbital) variation in mesospheric

International Polar Year Observations From the International Space Station

NASA Technical Reports Server (NTRS)

Pettit, Donald R.; Runco, Susan; Byrne, Gregory; Willis, Kim; Heydorn, James; Stefanov, William L.; Wilkinson, M. Justin; Trenchard, Michael

2006-01-01

Astronauts aboard the International Space Station (ISS) have several opportunities each day to observe and document high-latitude phenomena. Although lighting conditions, ground track and other viewing parameters change with orbital precessions and season, the 51.6 degree orbital inclination and 400 km altitude of the ISS provide the crew an excellent vantage point for collecting image-based data for IPY investigators. To date, the database of imagery acquired by the Crew Earth Observations (CEO) experiment aboard the ISS (http://eol.jsc.nasa.gov) contains more than 12,000 images of high latitude (above 50 degrees) events such as aurora, mesospheric clouds, sea-ice, high-latitude plankton blooms, volcanic eruptions, and snow cover. The ISS Program will formally participate in IPY through an activity coordinated through CEO entitled Synchronized Observations of Polar Mesospheric Clouds, Aurora and Other Large-scale Polar Phenomena from the ISS and Ground Sites. The activity will augment the existing collection of Earth images taken from the ISS by focusing astronaut observations on polar phenomena. NASA s CEO experiment will solicit requests by IPY investigators for ISS observations that are coordinated with or complement ground-based polar studies. The CEO imagery website (http://eol.jsc.nasa.gov) will provide an on-line form for IPY investigators to interact with CEO scientists and define their imagery requests. This information will be integrated into daily communications with the ISS crews about their Earth Observations targets. All data collected will be cataloged and posted on the website for downloading and assimilation into IPY projects.

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

NASA Astrophysics Data System (ADS)

Abakumov, Evgeny

2017-04-01

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

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.

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.

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.

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.

First Results From the Spatial Heterodyne Imager for Mesospheric Radicals (SHIMMER): Diurnal Variation of Mesospheric Hydroxyl

DTIC Science & Technology

2008-10-08

L01808, doi:10.1029/ 2005GL024048. Pickett, H. M., W. G. Read, K. K. Lee , and Y. L. Yung (2006b), Observa- tion of night OH in the mesosphere, Geophys. Res...Offermann, M. Riese, P. Preusse, D. F. Strobel , and J. M. Russell III (1997), Implica- tions of satellite OH observations for middle atmospheric H2O

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.

What is missing between model and Aura MLS observations in mesospheric OH?

NASA Astrophysics Data System (ADS)

Wang, S.; Li, K. F.; Zeng, Z.; Sander, S. P.; Shia, R. L.; Yung, Y. L.

2017-12-01

Recent Aura Microwave Limb Souder observations show higher mesospheric OH levels than earlier versions and previous satellite observations. The current photochemical model with standard chemistry is not able to accurately simulate MLS OH in the mesosphere. In particular, the model significantly underestimates OH over the altitude range of 60-80km. In the standard middle atmospheric chemistry, HOx over this altitude range is controled mainly through the reactions of H2O + hv (< 205 nm) → H + OH; H + O2 + M → HO2 + M; and OH + HO2 → H2O + O2. In an attempt to resolve the model-observation discrepancy, we adjust the rate coefficients of these reactions within recommended uncertainty ranges using an objective Bayesian approach. However, reasonable perturbations to these reactions are not capable of resolving the mesospheric discrepancy without introducing disagreements in other regions of the atmosphere. We explore possible new reactions in the Earth's atmosphere that are not included in current standard models. Some candidate reactions and their potential impacts on mesospheric HOx chemistry will be discussed. Our results urge new laboratory studies of these candidate reactions, whose rate coefficients have never been measured for the atmospheric conditions.

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.

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.

Constraints on vertical transport near the polar summer mesopause from PMC observations and modelling

NASA Astrophysics Data System (ADS)

Wilms, H.; Rapp, M.; Kirsch, A.

2016-12-01

The comparison of microphysical simulations of polar mesospheric cloud properties with ground based and satellite borne observations suggests that vertical wind variance imposed by gravity waves is an important prerequisite to realistically model PMC properties. This paper reviews the available observational evidence of vertical wind measurements at the polar summer mesopause (including their frequency content). Corresponding results are compared to vertical wind variance from several global models and implications for the transport of trace constituents in this altitude region are discussed.

Quasi-12 h inertia-gravity waves in the lower mesosphere observed by the PANSY radar at Syowa Station (39.6° E, 69.0° S)

NASA Astrophysics Data System (ADS)

Shibuya, Ryosuke; Sato, Kaoru; Tsutsumi, Masaki; Sato, Toru; Tomikawa, Yoshihiro; Nishimura, Koji; Kohma, Masashi

2017-05-01

The first observations made by a complete PANSY radar system (Program of the Antarctic Syowa MST/IS Radar) installed at Syowa Station (39.6° E, 69.0° S) were successfully performed from 16 to 24 March 2015. Over this period, quasi-half-day period (12 h) disturbances in the lower mesosphere at heights of 70 to 80 km were observed. Estimated vertical wavelengths, wave periods and vertical phase velocities of the disturbances were approximately 13.7 km, 12.3 h and -0.3 m s-1, respectively. Under the working hypothesis that such disturbances are attributable to inertia-gravity waves, wave parameters are estimated using a hodograph analysis. The estimated horizontal wavelengths are longer than 1100 km, and the wavenumber vectors tend to point northeastward or southwestward. Using the nonhydrostatic numerical model with a model top of 87 km, quasi-12 h disturbances in the mesosphere were successfully simulated. We show that quasi-12 h disturbances are due to wave-like disturbances with horizontal wavelengths longer than 1400 km and are not due to semidiurnal migrating tides. Wave parameters, such as horizontal wavelengths, vertical wavelengths and wave periods, simulated by the model agree well with those estimated by the PANSY radar observations under the abovementioned assumption. The parameters of the simulated waves are consistent with the dispersion relationship of the inertia-gravity wave. These results indicate that the quasi-12 h disturbances observed by the PANSY radar are attributable to large-scale inertia-gravity waves. By examining a residual of the nonlinear balance equation, it is inferred that the inertia-gravity waves are likely generated by the spontaneous radiation mechanism of two different jet streams. One is the midlatitude tropospheric jet around the tropopause while the other is the polar night jet. Large vertical fluxes of zonal and meridional momentum associated with large-scale inertia-gravity waves are distributed across a slanted region

Energy balance constraints on gravity wave induced eddy diffusion in the mesosphere and lower thermosphere

NASA Technical Reports Server (NTRS)

Strobel, D. F.; Apruzese, J. P.; Schoeberl, M. R.

1985-01-01

The constraints on turbulence improved by the mesospheric heat budget are reexamined, and the sufficiency of the theoretical evidence to support the hypothesis that the eddy Prandtl number is greater than one in the mesosphere is considered. The mesopause thermal structure is calculated with turbulent diffusion coefficients commonly used in chemical models and deduced from mean zonal wind deceleration. It is shown that extreme mesopause temperatures of less than 100 K are produced by the large net cooling. The results demonstrate the importance of the Prandtl number for mesospheric turbulence.

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.

Statistical parameters of nonisothermal lower ionospheric plasma in the electrically active mesosphere

NASA Astrophysics Data System (ADS)

Martynenko, S. I.; Rozumenko, V. T.; Tyrnov, O. F.; Manson, A. H.; Meek, C. E.

The large V/m electric fields inherent in the lower mesosphere play an essential role in lower ionospheric electrodynamics. They must be the cause of large variations in the electron temperature and the electron collision frequency and consequently of the transition of the ionospheric plasma in the lower part of the D region into a nonisothermal state. This study is based on the datasets on large mesospheric electric fields collected with the 2.2-MHz radar of the Institute of Space and Atmospheric Studies, University of Saskatchewan, Canada (52°N geographic latitude, 60.4°N geomagnetic latitude), and with the 2.3-MHz radar of the Kharkiv V. Karazin National University, Ukraine (49.6°N geographic latitude, 45.6°N geomagnetic latitude). The statistical analysis of these data is presented by [Meek, C.E., Manson, A.H., Martynenko, S.I., Rozumenko, V.T., Tyrnov, O.F. Remote sensing of mesospheric electric fields using MF radars. J. Atmos. Solar-Terr. Phys. 66, 881-890, 2004. 10.1016/j.jastp.2004.02.002]. The large mesospheric electric fields in the 60-67-km altitude range are experimentally established to follow a Rayleigh distribution in the 0 < E < 2.5 V/m interval. These data have permitted the resulting differential distributions of relative disturbances in the electron temperature, θ, and the effective electron collision frequency, η, to be determined. The most probable θ and η values are found to be in the 1.4-2.2 interval, and hence the nonstationary state of the lower part of the D region needs to be accounted for in studying processes coupling the electrically active mesosphere and the lower ionospheric plasma.

Mesospheric dust observations during the MAXIDUSTY campaign

NASA Astrophysics Data System (ADS)

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

2017-04-01

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

Solar mesosphere explorer: Experiment description

NASA Technical Reports Server (NTRS)

1977-01-01

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

Stratospheric and Mesospheric Trace Gas Studies Using Ground-Based mm-Wave Receivers

NASA Technical Reports Server (NTRS)

daZafra, Robert L.

1997-01-01

The goal of the proposed work was to understand the latitude structure of nitric oxide in the mesosphere and lower thermosphere. The problem was portrayed by a clear difference between predictions of the nitric oxide distribution from chemical/dynamical models and data from observations made by the Solar Mesosphere Explorer (SMEE) in the early to mid eighties. The data exhibits a flat latitude structure of NO, the models tend to produce at equatorial maximum.

Mesospheric signatures observed during 2010 minor stratospheric warming at King Sejong Station (62°S, 59°W)

NASA Astrophysics Data System (ADS)

Eswaraiah, S.; Kim, Yong Ha; Hong, Junseok; Kim, Jeong-Han; Ratnam, M. Venkat; Chandran, A.; Rao, S. V. B.; Riggin, Dennis

2016-03-01

A minor stratospheric sudden warming (SSW) event was noticed in the southern hemisphere (SH) during September (day 259) 2010 along with two episodic warmings in early August (day 212) and late October (day 300) 2010. Among the three warming events, the signature of mesosphere response was detected only for the September event in the mesospheric wind dataset from both meteor radar and MF radar located at King Sejong Station (62°S, 59°W) and Rothera (68°S, 68°W), Antarctica, respectively. The zonal winds in the mesosphere reversed approximately a week before the September SSW event, as has been observed in the 2002 major SSW. Signatures of mesospheric cooling (MC) in association with stratospheric warmings are found in temperatures measured by the Microwave Limb Sounder (MLS). Simulations of specified dynamics version of Whole Atmosphere Community Climate Model (SD-WACCM) are able to reproduce these observed features. The mesospheric wind field was found to differ significantly from that of normal years probably due to enhanced planetary wave (PW) activity before the SSW. From the wavelet analysis of wind data of both stations, we find that strong 14-16 day PWs prevailed prior to the SSW and disappeared suddenly after the SSW in the mesosphere. Our study provides evidence that minor SSWs in SH can result in significant effects on the mesospheric dynamics as in the northern hemisphere.

Does Polar Research Matter? (Invited)

NASA Astrophysics Data System (ADS)

Holmes, R.

2009-12-01

Climate change is one of the most serious challenges facing humanity. The polar regions are being disproportionately impacted, particularly in the Arctic where warming is greatly amplified. Moreover, there are strong feedbacks from the polar regions to the global climate system and sea level, so changes at the poles have global ramifications. Not surprisingly, polar research is often justified because of its relevance to global climate change. In spite of this, where are the “solutions” in the polar regions? For example, a scientist interested in climate change who studies tropical forests can work toward preserving the forests since deforestation is one of the main contributors to anthropogenic climate change. Are there similar direct solutions in polar regions? I will suggest that the answer is no, since the human controlled causes of climate change take place far removed from the poles. On the other hand, polar research has been absolutely essential for educating the public about climate change: the combination of important science and dramatic stories and images have captured the public’s attention more than for science originating in other regions. I will draw examples from several IPY projects that reached a broad public audience, and suggest that public education and outreach is the most important thing polar scientists can do to “make a difference” with respect to solving the climate crisis because environmental literacy (and an educated electorate) has been the factor that has most limited progress.

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).

The polar thermosphere of Venus

NASA Astrophysics Data System (ADS)

Mueller-Wodarg, Ingo; Rosenblatt, Pascal; Bruinsma, Sean; Yelle, Roger; Svedhem, Håkan; Forbes, Jeffrey M.; Withers, Paul; Keating Sci. Gerald, Sr.; Lopez-Valverde, Miguel Angel

The thermosphere of Venus has been extensively observed in-situ primarily by the Pioneer Venus Orbiter, but those measurements concentrated on the low latitude regions. Until recently, no in-situ observations were made of the polar thermosphere of Venus, and reference atmospheres such as the VTS3 and VIRA models relied on solar zenith angle trends inferred at low latitudes in order to extrapolate to polar latitudes. The Venus Express Atmospheric Drag Experiment (VExADE) carries out accurate orbital tracking in order to infer for the first time ever the densities in Venus' polar thermosphere near 180 km altitude at solar minimum. During 3 recent tracking campaigns we obtained density measurements that allow us to compare actual densities in those regions with those predicted by the reference atmosphere models. We constructed a hydrostatic diffusive equilibrium at-mosphere model that interpolates between the Venus Express remote sensing measurements in the upper mesosphere and lower thermosphere region and the in-situ drag measurements by VExADE. This paper will present and discuss our latest findings.

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

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

Climatic changes in the troposphere, stratosphere and lower mesosphere in 1979-2016

NASA Astrophysics Data System (ADS)

Perevedentsev, Y. P.; Shantalinskiy, K. M.; Guryanov, V. V.

2018-01-01

Changes in thermal characteristics in the atmospheric layer from 1000 to 0,1hPa are studied based on reanalysis data. It was demonstrated that during 1979-2016 temperature increased in the troposphere in January and July, while cooling was observed in the stratosphere, and air warming in lower mesosphere in summer. Most pronounced long-period cyclic changes were registered for temperature in the upper stratosphere and the lower mesosphere, and for ozone mixing ratio in the middle stratosphere.

Ozone Measurements in the Mesosphere During a Solar Proton Event

NASA Technical Reports Server (NTRS)

Lippert, W.; Felske, D.

1984-01-01

Charged particle precipitation in the Earth's atmosphere produces odd nitrogen and odd hydrogen. These species take part in catalytic reactions which destroy atmospheric ozone in the stratosphere and mesosphere. Modeling efforts regarding the impact of these ionization events on the neutral atmosphere describe ozone depletions in good agreement with observations in the stratosphere and mesosphere. The photochemical effects of the solar proton event (SPE) of August 1972 are discussed, and calculations for higher altitudes (70 to 90 km) are presented that indicate after a brief reduction during and immediately following intense particle precipitation, ozone will later reach higher concentrations than those present before the event.

Simultaneous mesosphere-thermosphere-ionosphere parameter measurements over Gadanki (13.5°N, 79.2°E): First results

NASA Astrophysics Data System (ADS)

Taori, A.; Dashora, N.; Raghunath, K.; Russell, J. M., III; Mlynczak, Martin G.

2011-07-01

We report first simultaneous airglow, lidar, and total electron content measurements in the mesosphere-thermosphere-ionosphere system behavior from Gadanki (13.5°N, 79.2°E). The observed variability in mesospheric temperatures and 630 nm thermospheric emission intensity shows large variations from one night to another with clear upward propagating waves at mesospheric altitudes. The deduced mesospheric temperatures compare well with Sounding of the Atmosphere Using Broadband Emission Radiometry (SABER)-derived temperatures, while the variability agrees well with lidar temperatures (on the night of simultaneous observations). The 630.0 nm thermospheric emission intensity and GPS-total electron content data exhibit occurrence of plasma depletions on the nights of 22-23 October and 22-23 May 2009, while no depletions are noted on the nearby nights of 23-24 October and 21-22 May 2009. These first simultaneous data reveal strong gravity-wave growth at upper mesospheric altitudes on the nights when plasma depletions were noted.

New measurements of vertical thermal structure and wind velocities in the Venusian mesosphere

NASA Astrophysics Data System (ADS)

Widemann, T.; Sandor, B. J.; Clancy, R. T.; Lellouch, E.

2009-04-01

The Venus mesosphere is a highly variable transition region, in latitude, local time and over short time scales, between the zonal circulation of the lower atmosphere and the diurnal, sub-solar to anti-solar circulation in the upper atmosphere. In the framework of European Space Agency's second campaign of ground-based observations (Feb 8-22, 2009) in support of the Venus-Express mission, we coordinated new observations sampling a large range of altitudes in the Venus mesosphere on Feb. 7-8 and Feb. 14-15 : (1) James Clerk Maxwell Submillimeter Telescope (JCMT) submillimeter lines observations of mesospheric CO spectral lines measurements of temperature, CO mixing ratio and winds over the 95-115 km altitude range (Clancy et al., 2008), while SO2, SO and HDO observations were also probed in the 70-100 km range ; (2) Canada-France-Hawaii Telescope (CFHT) optical spectropolarimeter ESPaDOnS observations of visible Solar Fraunhofer lines measuring the winds at cloud tops near 70 km and visible CO2 lines 1-2 scale heights above (Widemann et al., 2007, 2008). Synchronization of wind measurements helps characterize possible correlation patterns between wind variations in the lower and middle mesosphere over a day time scale. Preliminary results will be presented at the meeting. Clancy, R.T., Sandor, B.J., and Moriarty-Schieven, G.H. 2008, Planet. Space Sci. 56, 1320-1334. Widemann, T., Lellouch, E., and Campargue, A. 2007, New Wind Measurements in Venus' Lower Mesosphere From Visible Spectroscopy, Planet. Space Sci. 55, 1741-1756 Widemann, T., Lellouch, E., Donati, J.-F., 2008, Venus Doppler winds at Cloud Tops Observed with ESPaDOnS at CFHT, Planet. Space Sci. 56, 1320-133 --

Statistics on the parameters of nonisothermal ionospheric plasma in large mesospheric electric fields

NASA Astrophysics Data System (ADS)

Martynenko, S.; Rozumenko, V.; Tyrnov, O.; Manson, A.; Meek, C.

The large V/m electric fields inherent in the mesosphere play an essential role in lower ionospheric electrodynamics. They must be the cause of large variations in the electron temperature and the electron collision frequency at D region altitudes, and consequently the ionospheric plasma in the lower part of the D region undergoes a transition into a nonisothermal state. This study is based on the databases on large mesospheric electric fields collected with the 2.2-MHz radar of the Institute of Space and Atmospheric Studies, University of Saskatchewan, Canada (52°N geographic latitude, 60.4°N geomagnetic latitude) and with the 2.3-MHz radar of the Kharkiv V. Karazin National University (49.6°N geographic latitude, 45.6°N geomagnetic latitude). The statistical analysis of these data is presented in Meek, C. E., A. H. Manson, S. I. Martynenko, V. T. Rozumenko, O. F. Tyrnov, Remote sensing of mesospheric electric fields using MF radars, Journal of Atmospheric and Solar-Terrestrial Physics, in press. The large mesospheric electric fields is experimentally established to follow a Rayleigh distribution in the interval 0 mesosphere and the lower ionospheric plasma.

Mesospheric effects of solar ultraviolet variations - Further analysis of SME IR ozone and Nimbus 7 SAMS temperature data

NASA Astrophysics Data System (ADS)

Hood, L. L.; Huang, Z.; Bougher, S. W.

1991-07-01

In order to improve the constraints on models of the mesospheric response to solar UV variations, an analysis is conducted of the Solar Mesosphere Explorer (SME) IR ozone data and Nimbus 7 stratosphere and mesosphere sounder (SAMS) temperature data. Maximum low-altitude ozone and temperature-response amplitudes occur at about the same altitude, where a strong coupling between photochemical and thermal components of the mesospheric response is suggested by the simultaneous positive temperature and negative ozone response maxima. Increased Lyman-alpha dissociation of water vapor and temperature feedback are theorized to account for the negative ozone response. HO(x) chemical heating can increase as ozone destruction increases, and can therefore account for the positive temperature response.

Mesospheric effects of solar ultraviolet variations - Further analysis of SME IR ozone and Nimbus 7 SAMS temperature data

NASA Technical Reports Server (NTRS)

Hood, L. L.; Huang, Z.; Bougher, S. W.

1991-01-01

In order to improve the constraints on models of the mesospheric response to solar UV variations, an analysis is conducted of the Solar Mesosphere Explorer (SME) IR ozone data and Nimbus 7 stratosphere and mesosphere sounder (SAMS) temperature data. Maximum low-altitude ozone and temperature-response amplitudes occur at about the same altitude, where a strong coupling between photochemical and thermal components of the mesospheric response is suggested by the simultaneous positive temperature and negative ozone response maxima. Increased Lyman-alpha dissociation of water vapor and temperature feedback are theorized to account for the negative ozone response. HO(x) chemical heating can increase as ozone destruction increases, and can therefore account for the positive temperature response.

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.;

Mesospheric heating due to intense tropospheric convection

NASA Technical Reports Server (NTRS)

Taylor, L. L.

1979-01-01

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

Spherical solitons in Earth'S mesosphere plasma

NASA Astrophysics Data System (ADS)

Annou, K.; Annou, R.

2016-01-01

Soliton formation in Earth's mesosphere plasma is described. Nonlinear acoustic waves in plasmas with two-temperature ions and a variable dust charge where transverse perturbation is dealt with are studied in bounded spherical geometry. Using the perturbation method, a spherical Kadomtsev-Petviashvili equation that describes dust acoustic waves is derived. It is found that the parameters taken into account have significant effects on the properties of nonlinear waves in spherical geometry.

Investigating mesospheric mountain wave characteristics over New Zealand during DEEPWAVE

NASA Astrophysics Data System (ADS)

McLaughlin, P.; Taylor, M. J.; Pautet, P. D.; Kaifler, B.; Smith, S. M.

2017-12-01

The Deep Propagating Gravity Wave Experiment, "DEEPWAVE" was an international measurement and modelling program designed to characterize and predict the generation and propagation of a broad range of atmospheric gravity waves (GWs) with measurements extending from the ground to 100 km altitude. An analysis of 2 months of GW image data obtained during 2014 in New Zealand by a ground-based Advanced Mesospheric Temperature Mapper (AMTM) identified 19 events with clear signatures of orographic forcing. This is by far the largest occurrence of MW activity ever recorded at MLT heights. The observed events were quasi-stationary, exhibited a variety of horizontal wavelengths and lasted for > 1 hour. One prior study has reported such waves in the mesosphere over the Andes Mountain Range. We utilize data obtained by a collection of ground-based instrumentation operated at NIWA Lauder Station, NZ [45.0°S] to perform a detailed investigation of the generation and propagation of mountain waves into the upper mesosphere and to quantify their impact on this region using their measured momentum fluxes (MF). Instruments included an AMTM, a Rayleigh Lidar and an all-sky imager. The results focus on the derived MFs, comparing and contrasting their magnitudes and variability under different forcing conditions.

Energetic electrons and their effects on upper stratospheric and mesospheric ozone in May 1992

NASA Astrophysics Data System (ADS)

Pesnell, W. Dean; Goldberg, Richard A.; Chenette, D. L.; Gaines, E. E.; Jackman, Charles H.

The increased fluxes of precipitating energetic electrons (E>1 MeV) during highly relativistic electron events (HREs) produce ion concentrations in the upper stratosphere and lower mesosphere that exceed the background concentrations. Coupled ion-neutral chemistry models predict that this increased ionization should drive HOχ reactions and deplete mesospheric ozone by up to roughly 25%. As HREs become more intense and frequent during the declining phase of the solar cycle, it was also predicted that mesospheric ozone would show a solar cycle modulation as a result of these events. To calibrate the effect HREs have on mesospheric ozone, we have studied the May 1992 HRE with several instruments on the UARS. Electron fluxes measured with HEPS give the duration and spatial coverage of the HRE. Ozone data from MLS, CLAES, and HRDI were examined for the chemical signature of the HRE, ozone depletions within the magnetic L-shell limits of 3≤L<4. Using the multiple viewing angles of HRDI, we can compare mesospheric ozone at similar local solar times before, during, and after the HRE. This removes some of the ambiguity caused by progressive sampling of the diurnal cycle over a yaw cycle of the satellite. Although we analyzed one of the most intense HREs in the UARS database, we did not find HRE-induced changes in the ozone mixing ratio between altitudes of 55-75 km. Detecting a long-term trend in the ozone driven by precipitating electrons appears to require a substantial increase in the signal-to-noise ratio of the satellite measurements.

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.

Solar Mesosphere Explorer near-infrared spectrometer Measurements of 1.27-micron radiances and the inference of mesospheric ozone

NASA Astrophysics Data System (ADS)

Thomas, R. J.; Barth, C. A.; Rusch, W.; Sanders, R. W.

1984-10-01

Ozone in the mesosphere is determined from observations made by the near-infrared spectrometer experiment on the Solar Mesosphere Explorer satellite (SME) between 50 and 90 km over most latitudes at 3:00 p.m. local time. The spectrometer measures emission from 02 (1 Delta g) at 1.27 microns that is primarily due to the photodissociation of ozone. The instrument consists of a parabolic telescope that limits the field of view to less than 0.1 degrees, an Ebert-Fastie spectrometer, and a passively cooled lead sulfide detector system. The limb radiances, measured as the spacecraft spins, are inverted, producing volume emission rate profiles from which ozone densities are inferred. The vertical resolution is better than 3.5 km. The calculation of ozone accounts for quenching and atmospheric transmission of both solar radiation and 1.27 microns radiation. The existence of a secondary maximum of ozone density near 80 km is established. An error analysis shows that the effects of random errors in the data and in the analysis on the final ozone profile are less than 10 percent between 50 and 82 km.

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.

Unexpected Occurrence of Mesospheric Frontal Gravity Wave Events Over South Pole (90°S)

NASA Astrophysics Data System (ADS)

Pautet, P.-D.; Taylor, M. J.; Snively, J. B.; Solorio, C.

2018-01-01

Since 2010, Utah State University has operated an infrared Advanced Mesospheric Temperature Mapper at the Amundsen-Scott South Pole station to investigate the upper atmosphere dynamics and temperature deep within the vortex. A surprising number of "frontal" gravity wave events (86) were recorded in the mesospheric OH(3,1) band intensity and rotational temperature images (typical altitude of 87 km) during four austral winters (2012-2015). These events are gravity waves (GWs) characterized by a sharp leading wave front followed by a quasi-monochromatic wave train that grows with time. A particular subset of frontal gravity wave events has been identified in the past (Dewan & Picard, 1998) as "bores." These are usually associated with wave ducting within stable mesospheric inversion layers, which allow them to propagate over very large distances. They have been observed on numerous occasions from low-latitude and midlatitude sites, but to date, very few have been reported at high latitudes. This study provides new analyses of the characteristics of frontal events at high latitudes and shows that most of them are likely ducted. The occurrence of these frontal GW events over this isolated region strongly supports the existence of horizontally extensive mesospheric thermal inversion layers over Antarctica, leading to regions of enhanced stability necessary for GW trapping and ducting.

Space-borne observation of mesospheric bore by Visible and near Infrared Spectral Imager onboard the International Space Station

NASA Astrophysics Data System (ADS)

Hozumi, Y.; Saito, A.; Sakanoi, T.; Yamazaki, A.; Hosokawa, K.

2017-12-01

Mesospheric bores were observed by Visible and near Infrared Spectral Imager (VISI) of the ISS-IMAP mission (Ionosphere, Mesosphere, upper Atmosphere and Plasmasphere mapping mission from the International Space Station) in O2 airglow at 762 nm wavelength. The mesospheric bore is moving front of sharp jump followed by undulations or turbulence in the mesopause region. Since previous studies of mesospheric bore were mainly based on ground-based airglow imaging that is limited in field-of-view and observing site, little is known about its horizontal extent and global behavior. Space-borne imaging by ISS-IMAP/VISI provides an opportunity to study the mesospheric bore with a wide field-of-view and global coverage. A mesospheric bore was captured by VISI in two consecutive paths on 9 July 2015 over the south of African continent (48ºS - 54ºS and 15ºE). The wave front aligned with south-north direction and propagated to west. The phase velocity and wave length of the following undulation were estimated to 100 m/s and 30 km, respectively. Those parameters are similar to those reported by previous studies. 30º anti-clockwise rotation of the wave front was recognized in 100 min. Another mesospheric bore was captured on 9 May 2013 over the south Atlantic ocean (35ºS - 43ºS and 24ºW - 1ºE) with more than 2,200 km horizontal extent of wave front. The wave front aligned with southeast-northwest direction. Because the following undulation is recognized in the southwest side of the wave front, it is estimated to propagate to northeast direction. The wave front was modulated with 1,000 km wave length. This modulation implies inhomogeneity of the phase velocity.

Mars’ seasonal mesospheric transport seen through nitric oxide nightglow

NASA Astrophysics Data System (ADS)

Milby, Zachariah; Stiepen, Arnaud; Jain, Sonal; Schneider, Nicholas M.; Deighan, Justin; Gonzalez-Galindo, Francisco; Gerard, Jean-Claude; Stevens, Michael H.; Bougher, Stephen W.; Evans, J. Scott; Stewart, A. Ian; Chaffin, Michael; Crismani, Matteo; McClintock, William E.; Clarke, John T.; Holsclaw, Greg; Montmessin, Franck; Lefevre, Franck; Forget, Francois; Lo, Daniel Y.; Hubert, Benoît; Jakosky, Bruce

2017-10-01

We analyze the ultraviolet nightglow in the atmosphere of Mars through nitric oxide (NO) δ and γ band emissions as observed by the Imaging UltraViolet Spectrograph (IUVS) instrument onboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft when it is at apoapse and periapse.In the dayside thermosphere of Mars, solar extreme-ultraviolet radiation dissociates CO2 and N2 molecules. O(3P) and N(4S) atoms are carried from the dayside to the nightside by the day-night hemispheric transport process, where they descend through the nightside mesosphere and can radiatively recombine to form NO(C2Π). The excited molecules rapidly relax by emitting photons in the UV δ and γ bands. These emissions are indicators of the N and O atom fluxes from the dayside to Mars’ nightside and the descending circulation pattern from the nightside thermosphere to the mesosphere (e.g. Bertaux et al., 2005 ; Bougher et al., 1990 ; Cox et al., 2008 ; Gagné et al., 2013 ; Gérard et al., 2008 ; Stiepen et al., 2015, 2017).Observations of these emissions are gathered from a large dataset spanning different seasonal conditions.We present discussion on the variability in the brightness and altitude of the emission with season, geographical position (longitude), and local time, along with possible interpretation by local and global changes in the mesosphere dynamics. We show the possible impact of atmospheric waves forcing longitudinal variability and data-to-model comparisons indicating a wave-3 structure in Mars’ nightside mesosphere. Quantitative comparison with calculations of the Laboratoire de Météorologie Dynamique-Mars Global Climate Model (LMD-MGCM) suggests the model reproduces both the global trend of NO nightglow emission and its seasonal variation. However, it also indicates large discrepancies, with the emission up to a factor 50 times fainter in the model, suggesting that the predicted transport is too efficient toward the night winter pole in the thermosphere by

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

Statistical analysis of solar wind stream interface induced temperature effects on the upper mesosphere and lower thermosphere over SANAE IV, Antarctica

NASA Astrophysics Data System (ADS)

Ogunjobi, Olakunle; Sivakumar, Venkataraman; William; Sivla, T.

Using superposed epoch techniques, the TIMED (Thermosphere Ionosphere Mesosphere Energetic and Dynamics) and NOAA 15-18 (National Oceanic and Atmospheric Administration) satellites measurements are used to examine the response of the polar MLT (Mesosphere and Lower Thermosphere) temperature to energetic electron precipitation during solar wind stream interfaces (SI). We first investigate the relationship between the ionospheric absorption from the ground based riometer and degree of energetic electron precipitation from the MEPED (Medium Energy Proton and Electron Detectors) on board the NOAA satellites. By interpolating the energetic electron measurements from MEPED instruments, we can obtain the electron precipitation rates close in time to the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) temperature retrieval. Using measurements sorted over the vicinity of SANAE IV (South Africa National Antarctic Expedition IV), we investigate if there are significant temperature effects in the MLT altitude on SI arrival at Earth. The preliminary analysis indicate that there are no temperature increase below 100 km prior to the SI triggered precipitation; whereas a clear temperature increase is observed at 95 km immediately after the SI impact. The analysis on the SI geophysical properties indicates that an enhanced magnetospheric convection resulting to heating could be responsible for the temperature modification on SI arrival.

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.

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.

Studies of high latitude mesospheric turbulence by radar and rocket. I - Energy deposition and wave structure

NASA Technical Reports Server (NTRS)

Goldberg, R. A.; Fritts, D. C.; Chou, H.-G.; Schmidlin, F. J.; Barcus, J. R.

1988-01-01

The origin of wintertime mesospheric echoes observed with the mesosphere-stratosphere-troposphere radar at Poker Flat, Alaska, was studied by probing the mesosphere with in situ rocket measurements during echo occurrences in the early spring, 1985. Within the height range 65-75 km, the structure of the large scale wave field was identified. In this region, a gravity wave with a vertical wavelength of about 2 km was found superimposed on a wave with a larger amplitude and a vertical wavelength of about 6.6 km. Because of the close correlation between the smaller amplitude wave and the modulation observed in the S/N profiles, it is concluded that the smaller wave was dominant in generating turbulence within the middle atmosphere.

Ice surfaces in the mesosphere: Absence of dangling bonds in the presence of atomic oxygen

NASA Astrophysics Data System (ADS)

Boulter, James E.; Morgan, Christopher G.; Marschall, Jochen

2005-07-01

Ice deposition experiments in the presence of microwave discharge-dissociated molecular oxygen suggest heterogeneous interactions between dangling OH bonds on the ice surface and atomic oxygen. Ice films deposited on a gold substrate at temperatures of 115, 130, and 140 K from oxygen/water gas mixtures representative of the summertime polar mesosphere exhibit infrared absorption features characteristic of dangling bonds, whereas films grown in the presence of atomic oxygen do not. Dangling bond spectral features are shown to diminish rapidly when the microwave discharge is activated during ice deposition. Similar decreases were not seen when the gas stream was heated or when the ice film was slowly annealed from 130 to 160 K. One interpretation of these results is that atomic oxygen binds to dangling bond sites during ice growth, a phenomenon that may also occur during the formation of ice particles observed just below the cold summertime mesopause.

General relativistic razor-thin disks with magnetically polarized matter

NASA Astrophysics Data System (ADS)

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

2018-06-01

The origin of magnetic fields in the universe still remains unknown and constitutes one of the most intriguing questions in astronomy and astrophysics. Their significance is enormous since they have a strong influence on many astrophysical phenomena. In regards of this motivation, theoretical models of galactic disks with sources of magnetic field may contribute to understand the physics behind them. Inspired by this, we present a new family of analytical models for thin disks composed by magnetized material. The solutions are axially symmetric, conformastatic and are obtained by solving the Einstein-Maxwell Field Equations for continuum media without the test field approximation, and assuming that the sources are razor-thin disk of magnetically polarized matter. We find analytical expressions for the surface energy density, the pressure, the polarization vector, the electromagnetic fields, the mass and the rotational velocity for circular orbits, for two particular solutions. In each case, the energy-momentum tensor agrees with the energy conditions and also the convergence of the mass for all the solutions is proved. Since the solutions are well-behaved, they may be used to model astrophysical thin disks, and also may contribute as initial data in numerical simulations. In addition, the process to obtain the solutions is described in detail, which may be used as a guide to find solutions with magnetized material in General Relativity.

Spin polarized phases in strongly interacting matter: Interplay between axial-vector and tensor mean fields

NASA Astrophysics Data System (ADS)

Maruyama, Tomoyuki; Nakano, Eiji; Yanase, Kota; Yoshinaga, Naotaka

2018-06-01

The spontaneous spin polarization of strongly interacting matter due to axial-vector- and tensor-type interactions is studied at zero temperature and high baryon-number densities. We start with the mean-field Lagrangian for the axial-vector and tensor interaction channels and find in the chiral limit that the spin polarization due to the tensor mean field (U ) takes place first as the density increases for sufficiently strong coupling constants, and then the spin polarization due to the axial-vector mean field (A ) emerges in the region of the finite tensor mean field. This can be understood as making the axial-vector mean-field finite requires a broken chiral symmetry somehow, which is achieved by the finite tensor mean field in the present case. It is also found from the symmetry argument that there appear the type I (II) Nambu-Goldstone modes with a linear (quadratic) dispersion in the spin polarized phase with U ≠0 and A =0 (U ≠0 and A ≠0 ), although these two phases exhibit the same symmetry breaking pattern.

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

Spherical solitons in Earth’S mesosphere plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Annou, K., E-mail: kannou@cdta.dz; Annou, R.

2016-01-15

Soliton formation in Earth’s mesosphere plasma is described. Nonlinear acoustic waves in plasmas with two-temperature ions and a variable dust charge where transverse perturbation is dealt with are studied in bounded spherical geometry. Using the perturbation method, a spherical Kadomtsev–Petviashvili equation that describes dust acoustic waves is derived. It is found that the parameters taken into account have significant effects on the properties of nonlinear waves in spherical geometry.

Investigation of Mesospheric Metal Emission Signals from SCIAMACHY Limb Measurements

DTIC Science & Technology

2013-10-31

Mg seasonal variations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 5.3 Mg annual mean...19 5.4 Mg+ monthly means . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 5.5 Mg+ seasonal variations ...ground, which have a good vertical and tempo - ral resolution. Valuable information on mesospheric temperatures, wind speeds and wave propagation effects

Remote sensing of mesospheric dust layers using active modulation of PMWE by high-power radio-waves

NASA Astrophysics Data System (ADS)

Cohen, M.; Zhang, X.; Cohen, M.; Mahmoudian, A.; Scales, W.; Kosch, M. J.; M Farahani, M.; Mohebalhojeh, A.

2016-12-01

So-called polar mesospheric winter echoes (PMWE) are radar echoes observed during winter at altitudes around 50-80 km and are much weaker than their PMSE (Polar Mesospheric Summer Echoes) counterpart. Unlike PMSE, PMWE are less studied and understood. Breaking of gravity waves and the associated turbulence are proposed as the major source for PMWE echoes. The action of neutral turbulence alone does not appear to give a good explanation for PMWE. PMWE is also attributed to Bragg scatter from electron irregularities which result from charging of free electrons onto sub-visible particles. The temporal behavior of PMWE response to HF pump heating can be employed to diagnose the charged dust layer. Specifically, the rise and fall time of radar echo strength as well as relaxation and recovery time after heater turn-on and off are distinct parameters that are a function of radar frequency. This work presents the first study of the modulation of PMWE by artificial radiowave heating using computational modeling and experimental observation in different radar frequency bands. Variation of dust plasma parameters associated with PMWE such as dust radius, dust density, recombination rate, electron- and dust-neutral collision frequencies, photo-detachment current and electron temperature enhancement ratio are included. Computational results derived from different sets of parameters are considered and compared with recent observations at EISCAT using 224 MHz and 56 MHz radars. The agreement between the model results and the observations show the high potential of remote sensing of dust and plasma parameters associated with PMWE. Measurement of Te/Ti using ISR and simultaneous observations in two frequency bands may lead to a more accurate estimation of dust density and radius. The enhancement of backscattered signal in the HF band during PMWE heating is predicted for the first time. The required background dust-plasma parameters as well as heater power (Te/Ti) for the observation

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.

Dynamics of the Mesopause Region as Revealed in Images of Polar Mesospheric Clouds

NASA Astrophysics Data System (ADS)

Bailey, Scott; Thurairajah, Brentha; Nielsen, Kim; Lumpe, Jerry; Randall, Cora; Taylor, Michael J.; Zhao, Yucheng

Studying the geospace response to variable inputs and waves from the lower atmosphere is particularly important since the induced variability competes with the solar and magnetic driving from above. Consequences for telecommunications, re-entry and satellite operations still need to be explored. The extent to which the effects of this quiescent atmospheric variability are transmitted to the magnetosphere is yet to be resolved. We thus stand right now at an exciting research frontier: understanding the cause-and-effect chain that connects tropospheric and strato-/mesospheric variability with geospace processes. CAWSES-II Task Group 4 (TG4) will therefore elucidate the dynamical coupling from the low and middle atmosphere to geospace including the upper atmosphere, ionosphere, and magnetosphere, for various frequencies and scales, such as gravity waves, tides, and planetary waves, and for equatorial, middle, and high latitudes. Attacking the problem clearly requires a systems approach involving experimentalists, data analysts and modelers from different communities. For that purpose, the most essential part of TG4 is to encourage interactions between atmospheric scientists and plasma scientists on all occasions. Four project are established in TG4, i.e., Project 1: How do atmospheric waves connect tropospheric weather with ITM variability?, Project 2: What is the relation between atmospheric waves and ionospheric instabilities?, Project 3: How do the different types of waves interact as they propagate through the stratosphere to the ionosphere?, and Project 4: How do thermospheric disturbances generated by auroral processes interact with the neutral and ionized atmosphere? A joint project with TG2 is also proposed for the topic of Project 5: How does climate change affects atmospheric waves in the ITM? In this presentation we show current status and future plan of CAWSES-II TG4 activities of 2009-2013.

Satellite-based observations of tsunami-induced mesosphere airglow perturbations

NASA Astrophysics Data System (ADS)

Yang, Yu-Ming; Verkhoglyadova, Olga; Mlynczak, Martin G.; Mannucci, Anthony J.; Meng, Xing; Langley, Richard B.; Hunt, Linda A.

2017-01-01

Tsunami-induced airglow emission perturbations were retrieved by using space-based measurements made by the Sounding of the Atmosphere using Broad-band Emission Radiometry (SABER) instrument on board the Thermosphere-Ionosphere-Mesosphere Energetics Dynamics spacecraft. At and after the time of the Tohoku-Oki earthquake on 11 March 2011, and the Chile earthquake on 16 September 2015, the spacecraft was performing scans over the Pacific Ocean. Significant ( 10% relative to the ambient emission profiles) and coherent nighttime airglow perturbations were observed in the mesosphere following Sounding of the Atmosphere using Broad-band Emission Radiometry limb scans intercepting tsunami-induced atmospheric gravity waves. Simulations of emission variations are consistent with the physical characteristics of the disturbances at the locations of the corresponding SABER scans. Airglow observations and model simulations suggest that atmospheric neutral density and temperature perturbations can lead to the observed amplitude variations and multipeak structures in the emission profiles. This is the first time that airglow emission rate perturbations associated with tsunamis have been detected with space-based measurements.

Diurnal observations of HCl altitude variation in the 70-100 km mesosphere of Venus

NASA Astrophysics Data System (ADS)

Sandor, Brad J.; Todd Clancy, R.

2017-07-01

First submm spectroscopic observations of the 625.9 GHz H35Cl absorption lines of the Venus dayside atmosphere were obtained with the James Clerk Maxwell Telescope (JCMT) on March 2, 2013. These data, which support retrieval of HCl altitude distributions in the Venus mesosphere (70-100 km), are presented here and compared with previously reported JCMT observations of Venus nightside HCl (Sandor et al., 2012). The measured dayside profile agrees with that of the nightside, indicating no diurnal variation is present. More specifically, the nightside spectra revealed a secular decrease of upper mesospheric HCl between observations one month apart, at fixed latitude and local time. The dayside profile reported here presents upper mesospheric abundances that are bracketed by the two previously measured nightside profiles, indicating that if diurnal variation is present, it must be weaker than the secular variations occurring at fixed local time. The previous study, which measured nightside HCl abundances above 85 km to be much smaller than predicted from photochemical modeling, suggested a dynamical explanation for the disagreement wherein nightside downwelling associated with the SubSolar to AntiSolar (SSAS) atmospheric circulation might suppress upper mesospheric abundances predicted purely from photochemistry. However a straightforward prediction from the proposed mechanism is that HCl abundance on the dayside, where the SSAS drives upward rather than downward transport should at least agree with, and perhaps exceed that of the photochemical model. The finding that dayside HCl abundance agrees with that of the nightside, hence also is much smaller than that of the model shows the SSAS hypothesis to be incorrect.

Origin of refractive index fluctuations in the mesosphere as opposed to the stratosphere and troposphere

NASA Technical Reports Server (NTRS)

Rottger, J.

1983-01-01

Mesospheric echoes are strongly influenced by the electron density profile of the ionospheric D region. These echoes therefore are only observed during daylight hours or high energy particle precipitation. The turbulence occurs in layers, which often confines the radar echoes to rather thin regions of several 100 m vertical extent, although layers as thick as several kilometers are also observed. Evaluable echoes are not observed through the entire altitude region of the mesosphere for the given power aperture product. The echoes indicate temporal variation.

Asymmetries in ozone depressions between the polar stratospheres following a solar proton event

NASA Technical Reports Server (NTRS)

Maeda, K.; Heath, D. F.

1978-01-01

Ozone depletions in the polar stratosphere during the energetic solar proton event on 4 August 1972 were observed by the backscattered ultraviolet (BUV) experiments on the Nimbus 4 satellite. The observed ozone contents, the ozone depressions and their temporal variations above the 4 mb level exhibited distinct asymmetries between the northern and southern hemispheres. Since the ozone destroying solar particles precipitate rather symmetrically into the two polar atmospheres, due to the geomagnetic dipole field, it is suggested that these asymmetries may be explained in terms of the differences in dynamics between the summer and the winter polar atmospheres. In the summer (northern) hemisphere, the stratospheric and mesospheric ozone depletion and recovery are smooth functions of time due to the preponderance of undistributed orderly flow in this region. On the other hand, the temporal variation of the upper stratospheric ozone in the winter polar atmosphere (southern hemisphere) exhibits large amplitude irregularities. These characteristic differences between the two polar atmospheres are also evident in the vertical distributions of temperatures and winds observed by balloons and rocket soundings.

Temperature minima in the average thermal structure of the middle mesosphere (70 - 80 km) from analysis of 40- to 92-km SME global temperature profiles

NASA Technical Reports Server (NTRS)

Clancy, R. Todd; Rusch, David W.; Callan, Michael T.

1994-01-01

Global temperatures have been derived for the upper stratosphere and mesosphere from analysis of Solar Mesosphere Explorer (SME) limb radiance profiles. The SME temperature represent fixed local time observations at 1400 - 1500 LT, with partial zonal coverage of 3 - 5 longitudes per day over the 1982-1986 period. These new SME temperatures are compared to the COSPAR International Ionosphere Reference Atmosphere 86 (CIRA 86) climatology (Fleming et al., 1990) as well as stratospheric and mesospheric sounder (SAMS); Barnett and Corney, 1984), National Meteorological Center (NMC); (Gelman et al., 1986), and individual lidar and rocket observations. Significant areas of disagreement between the SME and CIRA 86 mesospheric temperatures are 10 K warmer SME temperatures at altitudes above 80 km. The 1981-1982 SAMS temperatures are in much closer agreement with the SME temperatures between 40 and 75 km. Although much of the SME-CIRA 86 disagreement probably stems from the poor vertical resolution of the observations comprising the CIRA 86 modelm, some portion of the differences may reflect 5- to 10-year temporal variations in mesospheric temperatures. The CIRA 86 climatology is based on 1973-1978 measurements. Relatively large (1 K/yr) 5- to 10-year trends in temperatures as functions of longitude, latitude, and altitude have been observed for both the upper stratosphere (Clancy and Rusch, 1989a) and mesosphere (Clancy and Rusch, 1989b; Hauchecorne et al., 1991). The SME temperatures also exhibit enhanced amplitudes for the semiannual oscillation (SAO) of upper mesospheric temperatures at low latitudes, which are not evident in the CIRA 86 climatology. The so-called mesospheric `temperature inversions' at wintertime midlatitudes, which have been observed by ground-based lidar (Hauschecorne et al., 1987) and rocket in situ measurements (Schmidlin, 1976), are shown to be a climatological aspect of the mesosphere, based on the SME observations.

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.

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).

Laboratory Studies Offer New Insights for Mesospheric Nightglow

NASA Astrophysics Data System (ADS)

Kalogerakis, K. S.; Matsiev, D.

2017-12-01

The hydroxyl radical has a key role in the chemistry and energetics of the Earth's middle atmosphere. A detailed knowledge of the rate constants and relevant pathways for OH(high v) vibrational relaxation by atomic and molecular oxygen and their temperature dependence is absolutely critical for understanding mesospheric OH and extracting reliable chemical heating rates from atmospheric observations. We have developed laser-based experimental approaches to study the complex collisional energy transfer processes involving the OH radical and other relevant atmospheric species. 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. Our recent laboratory measurements corroborated the aforementioned result for OH(v = 9) + O and provided important new insights on the multi-quantum energy transfer pathways involved. We will discuss relevant atmospheric implications, including warranted revisions of mesospheric nightglow models. Research supported by SRI International Internal R&D and NSF Aeronomy Grant AGS-1441896. Previously funded by NASA Geospace Science Grant NNX12AD09G.

iss031e116058

NASA Image and Video Library

2012-06-13

ISS031-E-116058 (13 June 2012) --- Polar mesospheric clouds in the Northern Hemisphere are featured in this image photographed by an Expedition 31 crew member on the International Space Station. In both the Northern and Southern Hemisphere, during their respective late spring and early summer seasons, polar mesospheric clouds are at the peak of their visibility. Visible from the ground during twilight, aircraft in flight, and the International Space Station, they typically appear as delicate shining threads against the darkness of space?hence their other name of noctilucent or ?night-shining? clouds. On the same day this image was taken from the space station while it was passing over the night-darkened Tibetan Plateau, polar mesospheric clouds were also visible to aircraft flying above Canada. In addition to this still image, the space station crew took a time-lapse image sequence of polar mesospheric clouds several days earlier (June 5, 2012) while passing over western Asia; this is first such sequence of images of the phenomena taken from orbit. Polar mesospheric clouds form between 76-85 kilometers above the Earth?s surface, when there is sufficient water vapor at these high altitudes to freeze into ice crystals. The clouds are illuminated by the setting sun while the ground surface below is in darkness, lending them their night-shining properties. In addition to the illuminated tracery of polar mesospheric clouds trending across the center of the image, lower layers of the atmosphere are also illuminated; the lowest layer of the atmosphere, the stratosphere, is indicated by dim orange and red tones. While the exact cause of formation of polar mesospheric clouds is still debated?dust from meteors, global warming, and rocket exhaust have all been suggested as contributing factors?recent research suggests that changes in atmospheric gas composition or temperature has caused the clouds to become brighter over time.

Seasonal Transport in Mars' Mesosphere-Thermosphere revealed by Nitric Oxide nightglow

NASA Astrophysics Data System (ADS)

Royer, E. M.; Stiepen, A.; Schneider, N. M.; Jain, S.; Milby, Z.; Deighan, J.; Gonzalez-Galindo, F.; Bougher, S. W.; Gerard, J. C. M. C.; Stevens, M. H.; Evans, J. S.; Stewart, I. F.; Chaffin, M.; McClintock, B.; Clarke, J. T.; Montmessin, F.; Holsclaw, G.; Lefèvre, F.; Forget, F.; Lo, D.; Hubert, B. A.; Jakosky, B. M.

2017-12-01

We analyze the ultraviolet nightglow in the atmosphere of Mars through the Nitric Oxide (NO) δ and γ band emissions observed by the Imaging Ultraviolet Spectrograph (IUVS, McClintock et al., 2015) when the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft is at apoapsis and periapsis. On the dayside thermosphere of Mars, solar extreme ultraviolet radiation dissociates CO2 and N2 molecules. O(3P) and N(4S) atoms are carried by the day-to-night hemispheric transport. They descend in the nightside mesosphere, where they can radiatively recombine to form NO(C2Π). The excited molecules rapidly relax by emitting UV photons in the δ and γ bands. These emissions are thus indicators of the N and O atom fluxes transported from the dayside to Mars' nightside and the descending circulation pattern from the nightside thermosphere to the mesosphere (e.g. Bertaux et al., 2005 ; Bougher et al., 1990 ; Cox et al., 2008 ; Gagné et al., 2013 ; Gérard et al., 2008 ; Stiepen et al., 2015, 2017). A large dataset of nightside disk images and vertical limb scans during southern winter, fall equinox and southern summer conditions have been accumulated since the beginning of the mission. We will present a discussion regarding the variability of the brightness and altitude of the emission with season, geographical position (longitude) and local time and possible interpretation for local and global changes in the mesosphere dynamics. We show the possible impact of atmospheric waves structuring the emission longitudinally and indicating a wave-3 structure in Mars' nightside mesosphere. Quantitative comparison with calculations from the LMD-MGCM (Laboratoire de Météorologie Dynamique-Mars Global Climate Model) show that the model globally reproduces the trends of the NO nightglow emission and its seasonal variation but also indicates large discrepancies (up to a factor 50 fainter in the model) suggesting that the predicted transport is too efficient toward the night winter pole

Spatial and Seasonal Variability of Temperature in CO2 Emission from Mars' Mesosphere

NASA Astrophysics Data System (ADS)

Livengood, Timothy A.; Kostiuk, Theodor; Hewagama, Tilak; Kolasinski, John R.; Henning, Wade; Fast, Kelly Elizabeth; Sonnabend, Guido; Sornig, Manuela

2017-10-01

We have observed non-local thermodynamic equilibrium (non-LTE) emission of carbon dioxide that probes Mars’ mesosphere in 2001, 2003, 2007, 2012, 2014, and 2016. These measurements were conducted at 10.6 μm wavelength using the Goddard Space Flight Center Heterodyne Instrument for Planetary Winds and Composition (HIPWAC) from the NASA Infrared Telescope Facility (IRTF) at resolving power (1-33)×106. The Maxwellian broadening of the emission line can be measured at this resolution, providing a direct determination of temperature in the mesosphere. The nonLTE line appears as a narrow emission core within a broad absorption formed by tropospheric CO2, which provides temperature information reaching down to the martian surface, while the mesospheric line probes temperature at about 60-80 km altitude. We will report on the spatial distribution of temperature and emission line strength with local solar time on Mars, with latitude, as well as long-term variability including seasonal effects that modify the overall thermal structure of the atmosphere. These remote measurements complement results from orbital spacecraft through access to a broad range of local solar time on each occasion.This work has been supported by the NASA Planetary Astronomy and Solar Systems Observations Programs

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.

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.

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.

Earth Observations

NASA Image and Video Library

2010-06-16

ISS024-E-006136 (16 June 2010) --- Polar mesospheric clouds, illuminated by an orbital sunrise, are featured in this image photographed by an Expedition 24 crew member on the International Space Station. Polar mesospheric, or noctilucent (?night shining?), clouds are observed from both Earth?s surface and in orbit by crew members aboard the space station. They are called night-shining clouds as they are usually seen at twilight. Following the setting of the sun below the horizon and darkening of Earth?s surface, these high clouds are still briefly illuminated by sunlight. Occasionally the ISS orbital track becomes nearly parallel to Earth?s day/night terminator for a time, allowing polar mesospheric clouds to be visible to the crew at times other than the usual twilight due to the space station altitude. This unusual photograph shows polar mesospheric clouds illuminated by the rising, rather than setting, sun at center right. Low clouds on the horizon appear yellow and orange, while higher clouds and aerosols are illuminated a brilliant white. Polar mesospheric clouds appear as light blue ribbons extending across the top of the image. These clouds typically occur at high latitudes of both the Northern and Southern Hemispheres, and at fairly high altitudes of 76?85 kilometers (near the boundary between the mesosphere and thermosphere atmospheric layers). The ISS was located over the Greek island of Kos in the Aegean Sea (near the southwestern coastline of Turkey) when the image was taken at approximately midnight local time. The orbital complex was tracking northeastward, nearly parallel to the terminator, making it possible to observe an apparent ?sunrise? located almost due north. A similar unusual alignment of the ISS orbit track, terminator position, and seasonal position of Earth?s orbit around the sun allowed for striking imagery of polar mesospheric clouds over the Southern Hemisphere earlier this year.

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

Do minor sudden stratospheric warmings in the Southern Hemisphere (SH) impact coupling between stratosphere and mesosphere-lower thermosphere (MLT) like major warmings?

NASA Astrophysics Data System (ADS)

Eswaraiah, S.; Kim, Yong Ha; Liu, Huixin; Ratnam, M. Venkat; Lee, Jaewook

2017-08-01

We have investigated the coupling between the stratosphere and mesosphere-lower thermosphere (MLT) in the Southern Hemisphere (SH) during 2010 minor sudden stratospheric warmings (SSWs). Three episodic SSWs were noticed in 2010. Mesospheric zonal winds between 82 and 92 km obtained from King Sejong Station (62.22°S, 58.78°W) meteor radar showed the significant difference from usual trend. The zonal wind reversal in the mesosphere is noticed a week before the associated SSW similar to 2002 major SSW. The mesosphere wind reversal is also noticed in "Specified Dynamics" version of Whole Atmosphere Community Climate Model (SD-WACCM) and Ground-to-topside model of Atmosphere and Ionosphere for Aeronomy (GAIA) simulations. The similar zonal wind weakening/reversal in the lower thermosphere between 100 and 140 km is simulated by GAIA. Further, we observed the mesospheric cooling in consistency with SSWs using Microwave Limb Sounder data. However, the GAIA simulations showed warming between 130 and 140 km after few days of SSW. Thus, the observation and model simulation indicate for the first time that the 2010 minor SSW also affects dynamics of the MLT region over SH in a manner similar to 2002 major SSW.[Figure not available: see fulltext.

Modification of mesospheric OH and O3 during a measured highly relativistic electron precipitation event

NASA Technical Reports Server (NTRS)

Goldberg, R. A.; Jackman, C. H.; Backer, D. N.; Herrero, F. A.

1994-01-01

Highly relativistic electron precipitation events (HRE's) can provide a major source of energy affecting mesospheric constituents and ionization. Based on satellite data, these events are most pronounced near the minimum of the solar sunspot cycle, increasing in intensity, spectral hardness, and frequency of occurrence as the solar cycle declines. Since such events can be sustained up to several days, their integrated effect in the mesosphere can dominate over those of other energy sources such as relativistic electron precipitation events (REP's) and auroral precipitation. The energy deposition data to be discussed and analyzed were obtained by rocket at Poker Flat, Alaska, in May 1990 during a modest HRE observed at midday near the peak of the sunspot cycle. Using a NASA two dimensional model, significant enhancement of OH and depletion of O3 at 75 +/- 10 km altitude from the measured radiation are found. Estimates of enhanced effects were made for more intense HRE events, as might be expected during solar minimum. By causing O3 depletion, the electron precipitation can also regulate the penetration of solar UV radiation, which could affect the thermal properties of the mesosphere.

Changes in the concentration of mesospheric O3 and OH during a highly relativistic electron precipitation event

NASA Astrophysics Data System (ADS)

Goldberg, R. A.; Jackman, C. H.; Baker, D. N.; Herrero, F. A.

Highly relativistic electron precipitation events (HREs) can provide a major source of energy affecting ionization levels and minor constituents in the mesosphere. Based on satellite data, these events are most pronounced during the minimum of the solar sunspot cycle, increasing in intensity, spectral hardness and frequency of occurrence as solar activity declines. Furthermore, although the precipitating flux is modulated diurnally in local time, the noontime maximum is very broad, exceeding several hours. Since such events can be sustained up to several days, their integrated effect in the mesosphere can dominate over those of other external sources such as relativistic electron precipitation events (REPs) and auroral precipitation. In this work, the effects of HRE relativistic electrons on the neutral minor constituents OH and O3 are modeled during a modest HRE, to estimate their anticipated impact on mesospheric heating and dynamics. The data to be discussed and analyzed were obtained by rocket at Poker Flat, Alaska on May 13, 1990 during an HRE observed at midday near the peak of the sunspot cycle. Solid state detectors were used to measure the electron fluxes and their energy spectra. An x-ray scintillator was included to measure bremsstrahlung x-rays produced by energetic electrons impacting the upper atmosphere; however, these were found to make a negligible contribution to the energy deposition during this particular HRE event. Hence, the energy deposition produced by the highly relativistic electrons dominated within the mesosphere and was used exclusively to infer changes in the middle atmospheric minor constituent abundances. By employing a two-dimensional photochemical model developed for this region at Goddard Space Fight Center, it has been found that for this event, peak modifications in the neutral minor species occurred near 80 km. A maximum enhancement for OH was calculated to be over 40% at the latitude of the launch site, which in turn induced a

[Analysis of mechanism of transition zones among β, δ and γ dispersions in brain white matter and grey matter].

PubMed

Tian, Rui; Lu, Mai

2017-08-01

In order to explore the application of the dielectric properties of white matter and grey matter in β, δ and γ dispersion transition zones used in clinical medicine and microwave imaging technology, we calculated the dielectric constant and its increment by using Cole-Cole equation. Based on the mutation of the increment of dielectric constant, the frequency range of three dispersions were evaluated. The dominate dispersion and the corresponding polarization mechanism were analyzed by using Cole-Cole circle. The results showed that there are 3 transition zones in brain white matter, which occur between β and δ dispersion, δ and γ dispersion and β and γ dispersion respectively. In grey matter, there are only 2 transition zones, which are between β and δ dispersion and δ and γ dispersion respectively. By comparing the frequency range of white matter and grey matter, the frequency range in white matter is broader than that in grey matter for the transition zone of β and δ dispersion with the β dispersion occupying dominate position in both tissues, and the corresponding polarization mechanism is interfacial polarization. For the transition zone of δ and γ dispersion, the frequency range in white matter is also broader than that in grey matter with the δ dispersion occupying dominate position in both tissues, and the corresponding polarization mechanism is orientation polarization. This study can provide basic theory and reference for diagnosis of brain diseases and microwave imaging technology.

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.

The distribution of minor constituents in the stratosphere and lower mesosphere

NASA Technical Reports Server (NTRS)

Martell, E. A.

1973-01-01

The complex circulation processes within the stratosphere and mesosphere have been clarified by recent studies. The distribution of minor constituents in the middle atmosphere is significantly influenced by these transport processes. Rocket sampling results are discussed, giving attention to the sampling method, noble gases, methane, water vapor, molecular hydrogen, and carbon dioxide.

Impacts of Horizontal Propagation of Orographic Gravity Waves on the Wave Drag in the Stratosphere and Lower Mesosphere

NASA Astrophysics Data System (ADS)

Xu, Xin; Wang, Yuan; Xue, Ming; Zhu, Kefeng

2017-11-01

The impact of horizontal propagation of mountain waves on the orographic gravity wave drag (OGWD) in the stratosphere and lower mesosphere of the Northern Hemisphere is evaluated for the first time. Using a fine-resolution (1 arc min) terrain and 2.5°×2.5° European Centre for Medium-Range Weather Forecasts ERA-Interim reanalysis data during 2011-2016, two sets of OGWD are calculated offline according to a traditional parameterization scheme (without horizontal propagation) and a newly proposed scheme (with horizontal propagation). In both cases, the zonal mean OGWDs show similar spatial patterns and undergo a notable seasonal variation. In winter, the OGWD is mainly distributed in the upper stratosphere and lower mesosphere of middle to high latitudes, whereas the summertime OGWD is confined in the lower stratosphere. Comparison between the two sets of OGWD reveal that the horizontal propagation of mountain waves tends to decrease (increase) the OGWD in the lower stratosphere (middle to upper stratosphere and lower mesosphere). Consequently, including the horizontal propagation of mountain waves in the parameterization of OGWD can reduce the excessive OGWD in the lower stratosphere and strengthen the insufficient gravity wave forcing in the mesosphere, which are the known problems of traditional OGWD schemes. The impact of horizontal propagation is more prominent in winter than in summer, with the OGWD in western Tibetan Plateau, Rocky Mountains, and Greenland notably affected.

A thermosphere-ionosphere-mesosphere-electrodynamic general circulation model (time-GCM): Equinox solar cycle minimum simulations (30-500 km)

NASA Technical Reports Server (NTRS)

Roble, R. G.; Ridley, E. C.

1994-01-01

A new simulation model of the mesosphere, thermosphere, and ionosphere with coupled electrodynamics has been developed and used to calculate the global circulation, temperature and compositional structure between 30-500 km for equinox, solar cycle minimum, geomagnetic quiet conditions. The model incorporates all of the features of the National Center for Atmospheric Research (NCAR) thermosphere-ionosphere- electrodynamics general circulation model (TIE-GCM) but the lower boundary has been extended downward from 97 to 30 km (10 mb) and it includes the physical and chemical processes appropriate for the mesosphere and upper stratosphere. The first simulation used Rayleigh friction to represent gravity wave drag in the middle atmosphere and although it was able to close the mesospheric jets it severely damped the diurnal tide. Reduced Rayleigh friction allowed the tide to penetrate to thermospheric heights but did not close the jets. A gravity wave parameterization developed by Fritts and Lu (1993) allows both features to exist simultaneously with the structure of tides and mean flow dependent upon the strength of the gravity wave source. The model calculates a changing dynamic structure with the mean flow and diurnal tide dominant in the mesosphere, the in-situ generated semi-diurnal tide dominating the lower thermosphere and an in-situ generated diurnal tide in the upper thermosphere. The results also show considerable interaction between dynamics and composition, especially atomic oxygen between 85 and 120 km.

Night side distribution of SO2 content in Venus' upper mesosphere

NASA Astrophysics Data System (ADS)

Belyaev, D. A.; Evdokimova, D. G.; Montmessin, F.; Bertaux, J.-L.; Korablev, O. I.; Fedorova, A. A.; Marcq, E.; Soret, L.; Luginin, M. S.

2017-09-01

In this paper we present the first night side distribution of SO2 content in Venus' upper mesosphere (altitudes from 85 to 105 km). The dataset is based on the SPICAV UV stellar occultation experiment which took place onboard ESA's Venus Express (VEX) orbiter in 2006-2014. The UV channel of SPICAV spectrometer detected absorption bands of SO2 and CO2 in the spectral range 180-300 nm with a resolution of 1-2 nm while stellar light was occulted by the mesosphere. Altitude profiles of sulfur dioxide's volume mixing ratio (VMR) could be retrieved in the upper part of the mesosphere covering the whole night side on Venus. In parallel, we have reprocessed the terminator UV solar occultations dataset (Belyaev et al., 2012. Icarus 217, 740-751) in the same altitude range and extended its statistics until 2014. On average the SO2 VMR increases with altitude from 10-30 ppb at 85 km to 100-300 ppb at 100 km in both regimes of occultation. The midnight SO2 abundance appears to be 3-4 times higher than in the terminator region: 150-200 ppbv versus 50 pppv at altitude around 95 km. These new results were compared with the distribution of oxygen atoms, which are tracers of the global subsolar-antisolar (SS-AS) circulation at ∼100 km (the data provided by Soret et al., 2012 Icarus, 217, 849-855). The night time behavior looks similar for SO2 molecules and O atoms with a correlation coefficient Rcorr = 0.73. Moreover, the retrieved SO2 enrichment above 85 km appears to correlate with the density of H2SO4 droplets (Luginin et al., 2016; Icarus 277, 154-170).

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

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.

The role of the winter residual circulation in the summer mesopause regions in WACCM

NASA Astrophysics Data System (ADS)

Sanne Kuilman, Maartje; Karlsson, Bodil

2018-03-01

High winter planetary wave activity warms the summer polar mesopause via a link between the two hemispheres. Complex wave-mean-flow interactions take place on a global scale, involving sharpening and weakening of the summer zonal flow. Changes in the wind shear occasionally generate flow instabilities. Additionally, an altering zonal wind modifies the breaking of vertically propagating gravity waves. A crucial component for changes in the summer zonal flow is the equatorial temperature, as it modifies latitudinal gradients. Since several mechanisms drive variability in the summer zonal flow, it can be hard to distinguish which one is dominant. In the mechanism coined interhemispheric coupling, the mesospheric zonal flow is suggested to be a key player for how the summer polar mesosphere responds to planetary wave activity in the winter hemisphere. We here use the Whole Atmosphere Community Climate Model (WACCM) to investigate the role of the summer stratosphere in shaping the conditions of the summer polar mesosphere. Using composite analyses, we show that in the absence of an anomalous summer mesospheric temperature gradient between the equator and the polar region, weak planetary wave forcing in the winter would lead to a warming of the summer mesosphere region instead of a cooling, and vice versa. This is opposing the temperature signal of the interhemispheric coupling that takes place in the mesosphere, in which a cold and calm winter stratosphere goes together with a cold summer mesopause. We hereby strengthen the evidence that the variability in the summer mesopause region is mainly driven by changes in the summer mesosphere rather than in the summer stratosphere.

Ground-based microwave observations of ozone in the upper stratosphere and mesosphere

NASA Technical Reports Server (NTRS)

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

1994-01-01

A 9-month-long series of mesurements of ozone in the upper stratosphere and mesosphere is reported. The measurements are presented as monthly averages of profiles in blocks of roughly 20 min local time and as night-to-day ratios. An error analysis predicts accuracies of 5-26% for the monthly profiles and 2.5-9% for the ratios. The data are compared to historical data from Solar Mesosphere Explorer (SME) and limb infrared monitor of the stratosphere (LIMS), and it is shown how to remove the effect of different vertical resolution from the comparisons. The microwave data typically agree to better than 10% with SMF and nighttime LIMS ozone at all altitudes below the 0.1-mbar surface. Comparison of the microwave night-to-day ratio with the corresponding ratio from LIMS suggests that nonlocal thermodynamic equilibrium effects in the LIMS daytime data exceed 10% at all pressures less than or equal to 1 mbar.

Quasi 18 h wave activity in ground-based observed mesospheric H2O over Bern, Switzerland

NASA Astrophysics Data System (ADS)

Lainer, Martin; Hocke, Klemens; Rüfenacht, Rolf; Kämpfer, Niklaus

2017-12-01

Observations of oscillations in the abundance of middle-atmospheric trace gases can provide insight into the dynamics of the middle atmosphere. Long-term, high-temporal-resolution and continuous measurements of dynamical tracers within the strato- and mesosphere are rare but would facilitate better understanding of the impact of atmospheric waves on the middle atmosphere. Here we report on water vapor measurements from the ground-based microwave radiometer MIAWARA (MIddle Atmospheric WAter vapor RAdiometer) located close to Bern during two winter periods of 6 months from October to March. Oscillations with periods between 6 and 30 h are analyzed in the pressure range 0.02-2 hPa. Seven out of 12 months have the highest wave amplitudes between 15 and 21 h periods in the mesosphere above 0.1 hPa. The quasi 18 h wave signature in the water vapor tracer is studied in more detail by analyzing its temporal evolution in the mesosphere up to an altitude of 75 km. Eighteen-hour oscillations in midlatitude zonal wind observations from the microwave Doppler wind radiometer WIRA (WInd RAdiometer) could be identified within the pressure range 0.1-1 hPa during an ARISE (Atmospheric dynamics Research InfraStructure in Europe)-affiliated measurement campaign at the Observatoire de Haute-Provence (355 km from Bern) in France in 2013. The origin of the observed upper-mesospheric quasi 18 h oscillations is uncertain and could not be determined with our available data sets. Possible drivers could be low-frequency inertia-gravity waves or a nonlinear wave-wave interaction between the quasi 2-day wave and the diurnal tide.

Scattering cross section of mesospheric echoes and turbulence parameters from Gadanki radar observations

NASA Astrophysics Data System (ADS)

Selvaraj, D.; Patra, A. K.; Chandra, H.; Sinha, H. S. S.; Das, U.

2014-11-01

We present a comprehensive study on radar scattering cross section of mesospheric echoes and mesospheric turbulence parameters based on several days of observations made during two rocket-radar campaigns, one in July 2004 and another in April 2005, meant for studying mesospheric turbulence. Radar scattering cross section was found to have large local time and day-to-day variability and was found to be as low as 3.1×10-18 m-1 and as high as 1×10-14 m-1 and the median values were in the range of 4.4×10-18-4.7×10-16 m-1. Echoes connected with the low value of scattering cross section could be detected only when a long pulse width was used. Turbulence parameters were found to vary remarkably with time of the day and also from one day to another. In July, the turbulent kinetic energy (TKE) dissipation rate, outer scale and inner scale were in the range of 0.08-150 mW/kg, 33-1500 m, and 1.9-50 m, respectively, and their median values were in the range of 5-52 mW/kg, 293-977 m, and 2-31 m, respectively. In April, these estimates were in the range of 0.9-69 mW/kg, 38-1081 m, and 4-21 m, respectively, and their median values were in the range of 1-12 mW/kg, 140-378 m, and 8-13 m, respectively. These parameters are found to agree quite well with those estimated from rocket-borne observations, which were in the range of 4-117 mW/kg, 220-1475 m, and 15-31 m, respectively, in July and 2-36 mW/kg, 170-680 m, and 17-37 m, respectively, in April. Interestingly, the inner and outer scales estimated using both radar and rocket observations agree exceedingly well with model values. These results are compared in detail with those reported from low, middle and high latitudes including model and discussed in the light of current knowledge of mesospheric turbulence.

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.

Understanding the Latitude Structure of Nitric Oxide in the Mesosphere and Lower Thermosphere

NASA Technical Reports Server (NTRS)

Fuller-Rowell, T.J.

1997-01-01

The goal of the proposed work was to understand the latitude structure of nitric oxide in the mesosphere and lower thermosphere. The problem was portrayed by a clear difference between predictions of the nitric oxide distribution from chemical/dynamical models and data from observations made by the Solar Mesosphere Explorer (SMEE) in the early to mid eighties. The data exhibits a flat latitude structure of NO, the models tend to produce at equatorial maximum. The first task was to use the UARS-HALOE data to confirm the SME observations. The purpose of this first phase was to verify the UARS-NO structure is consistent with the SME data. The next task was to determine the cause of the discrepancy between modeled and observed nitric oxide latitude structure. The result from the final phase indicated that the latitude structure in the Photo-Electron (PE) production rate was the most important.

Climatology and inter-annual variability of the polar mesospheric winds inferred from meteor radar observations over Sodankylä (67N, 26E) during solar cycle 24

NASA Astrophysics Data System (ADS)

Lukianova, Renata; Kozlovsky, Alexander; Lester, Mark

2018-06-01

The inter-annual variability, climatological mean wind and tide fields in the northern polar mesosphere/lower thermosphere region of 82-98 km height are studied using observations by the meteor radar which has operated continuously during solar cycle 24 (from December 2008 onward) at the Sodankylä Geophysical Observatory (67N, 26E). Summer mean zonal winds are characterized by westward flow, up to 25 m/s, at lower heights and eastward flow, up to 30 m/s, at upper heights. In the winter an eastward flow, up to 10 m/s, dominates at all heights. The meridional winds are characterized by a relatively weak poleward flow (few m/s) in the winter and equatorward flow in the summer, with a jet core (∼15 m/s) located slightly below 90 km. These systematically varying winds are dominated by the semidiurnal tides. The largest amplitudes, up to 30 m/s, are observed at higher altitudes in winter and a secondary maximum is seen in August-September. The diurnal tides are almost a factor of two weaker and peak in summer. The variability of individual years is dominated by the winter perturbations. During the period of observations major sudden stratospheric warmings (SSW) occurred in January 2009 and 2013. During these events the wind fields were strongly modified. The lowest altitude eastward winds maximized up to 25 m/s, that is by more twice that of the non-SSW years. The poleward flow considerably increases (up 10 m/s) and extends from the lower heights throughout the whole altitude range. The annual pattern in temperature at ∼90 km height over Sodankyla consists of warm winters (up to 200 K) and cold summers (∼120 K).

Laboratory Studies of Vibrational Relaxation: Important Insights for Mesospheric OH

NASA Astrophysics Data System (ADS)

Kalogerakis, K. S.; Matsiev, D.

2016-12-01

The hydroxyl radical has a key role in the chemistry and energetics of the Earth's middle atmosphere. A detailed knowledge of the rate constants and relevant pathways for OH(high v) vibrational relaxation by atomic and molecular oxygen and their temperature dependence is absolutely critical for understanding mesospheric OH and extracting reliable chemical heating rates from atmospheric observations. We have developed laser-based experimental approaches to study the complex collisional energy transfer processes involving the OH radical and other relevant atmospheric species. Previous work in our laboratory indicated that the total removal rate constant for OH(v = 9) + O at room temperature is more than one order of magnitude larger than that for removal by O2. Thus, O atoms are expected to significantly influence the intensity and vibrational distribution extracted from the Meinel OH(v) emissions. We will report our most recent laboratory experiments that corroborate the aforementioned result for fast OH(v = 9) + O and provide important new insights on the mechanistic pathways involved. We will also highlight relevant atmospheric implications, including warranted revisions of current mesospheric OH models. Research supported by SRI International Internal R&D and NSF Aeronomy grant AGS-1441896. Previously supported by NASA Geospace Science grant NNX12AD09G.

Lidar Probing of the Mesosphere: Simultaneous Observations of Sporadic Sodium and Iron Formations, Calcium Ion Layers, Neutral Temperature and Winds

NASA Technical Reports Server (NTRS)

Kane, Timothy J.; Qian, Jun; Scherrer, Daniel R.; Senft, Daniel C.; Pfenninger, W. Matthew; Papen, George C.; Gardner, Chester S.

1992-01-01

Meteoritic ablation in the upper atmosphere is the commonly accepted source of the mesospheric metals between 80 and 105 km. The vertical and temporal behavior of some of these metals can be probed with high accuracy and resolution using resonance fluorescence lidar techniques. Of considerable interest in recent years has been the sporadic and rapid formation of thin, dense enhancements in these metallic layers. Since late Mar. 1991, the UIUC CEDAR lidar system, located at the Urbana Atmospheric Observatory, has been routinely operating at the Fe resonance line of 372 nm in order to probe the mesospheric Fe layer. In Nov. 1991, the capability to investigate mesospheric Ca(+) at the resonance line of 393.4 nm was added. The lidar's eximer-pumped dye laser uses Exciton QUI laser dye dissolved in p-dioxane, which can lase at both the Fe and Ca(+) frequencies. Various aspects of this investigation are discussed.

Performance evaluation of low-cost airglow cameras for mesospheric gravity wave measurements

NASA Astrophysics Data System (ADS)

Suzuki, S.; Shiokawa, K.

2016-12-01

Atmospheric gravity waves significantly contribute to the wind/thermal balances in the mesosphere and lower thermosphere (MLT) through their vertical transport of horizontal momentum. It has been reported that the gravity wave momentum flux preferentially associated with the scale of the waves; the momentum fluxes of the waves with a horizontal scale of 10-100 km are particularly significant. Airglow imaging is a useful technique to observe two-dimensional structure of small-scale (<100 km) gravity waves in the MLT region and has been used to investigate global behaviour of the waves. Recent studies with simultaneous/multiple airglow cameras have derived spatial extent of the MLT waves. Such network imaging observations are advantageous to ever better understanding of coupling between the lower and upper atmosphere via gravity waves. In this study, we newly developed low-cost airglow cameras to enlarge the airglow imaging network. Each of the cameras has a fish-eye lens with a 185-deg field-of-view and equipped with a CCD video camera (WATEC WAT-910HX) ; the camera is small (W35.5 x H36.0 x D63.5 mm) and inexpensive, much more than the airglow camera used for the existing ground-based network (Optical Mesosphere Thermosphere Imagers (OMTI) operated by Solar-Terrestrial Environmental Laboratory, Nagoya University), and has a CCD sensor with 768 x 494 pixels that is highly sensitive enough to detect the mesospheric OH airglow emission perturbations. In this presentation, we will report some results of performance evaluation of this camera made at Shigaraki (35-deg N, 136-deg E), Japan, where is one of the OMTI station. By summing 15-images (i.e., 1-min composition of the images) we recognised clear gravity wave patterns in the images with comparable quality to the OMTI's image. Outreach and educational activities based on this research will be also reported.

Vertical temperature and density patterns in the Arctic mesosphere analyzed as gravity waves

NASA Technical Reports Server (NTRS)

Eberstein, I. J.; Theon, J. S.

1975-01-01

Rocket soundings conducted from high latitude sites in the Arctic mesosphere are described. Temperature and wind profiles and one density profile were observed independently to obtain the thermodynamic structure, the wind structure, and their interdependence in the mesosphere. Temperature profiles from all soundings were averaged, and a smooth curve (or series of smooth curves) drawn through the points. A hydrostatic atmosphere based on the average, measured temperature profile was computed, and deviations from the mean atmosphere were analyzed in terms of gravity wave theory. The vertical wavelengths of the deviations were 10-20 km, and the wave amplitudes slowly increased with height. The experimental data were matched by calculated gravity waves having a period of 15-20 minutes and a horizontal wavelength of 60-80 km. The wind measurements are consistent with the thermodynamic measurements. The results also suggest that gravity waves travel from East to West with a horizontal phase velocity of approximately 60 m sec-1.

Six years of mesospheric CO estimated from ground-based frequency-switched microwave radiometry at 57° N compared with satellite instruments

NASA Astrophysics Data System (ADS)

Forkman, P.; Christensen, O. M.; Eriksson, P.; Urban, J.; Funke, B.

2012-06-01

Measurements of mesospheric carbon monoxide, CO, provide important information about the dynamics in the mesosphere region since CO has a long lifetime at these altitudes. Ground-based measurements of mesospheric CO made at the Onsala Space Observatory, OSO, (57° N, 12° E) are presented. The dataset covers the period 2002-2008 and is hence uniquely long. The simple and stable 115 GHz frequency-switched radiometer, calibration method, retrieval procedure and error characterization are described. A comparison between our measurements and co-located CO measurements from the satellite sensors ACE-FTS on Scisat (v2.2), MLS on Aura (v3-3), MIPAS on Envisat (V3O_CO_12 + 13 and V4O_CO_200) and SMR on Odin (v225 and v021) is done. Our instrument, OSO, and the four satellite instruments show the same general variation of the vertical distribution of mesospheric CO in both the annual cycle and in shorter time period events with high CO mixing ratios during winter and very low amounts during summer in the observed 55-85 km altitude range. During 2004-2008 the agreement of the OSO instrument and the satellite sensors ACE-FTS, MLS and MIPAS(200) is good in the altitude range 55-70 km. Above 70 km OSO show up to 25% higher CO column values compared to both ACE and MLS. For the time period 2002-2003 CO from MIPAS(12 + 13) is up to 60% lower than OSO between 55 and 70 km. Mesospheric CO from the two versions of SMR deviates up to ±65% when compared to OSO, but the analysis is based on only a few co-locations.

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

Modeling Study of Planetary Waves in the Mesosphere Lower Thermosphere (MLT)

NASA Technical Reports Server (NTRS)

Mengel, J. G.; Mayr, H. g.; Drob, D.; Porter, H. S.; Hines, C. O.

2003-01-01

For comparison with measurements from the TIMED satellite and coordinated ground based observations, we present results from our Numerical Spectral Model (NSM) that incorporates the Doppler Spread Parameterization (Hines, 1997) for small-scale gravity waves (GWs). We discuss the planetary waves (PWs) that are purely generated by dynamical interactions, i.e., without explicitly specifying excitation sources related for example to tropospheric convection or topography. With tropospheric heating that reproduces the observed zonal jets near the tropopause and the accompanying reversal in the latitudinal temperature variation, which is conducive to baroclinic instability, long period PWs are produced that propagate up into the stratosphere to affect the wave driven equatorial oscillations (QBO and SAO) extending into the upper mesosphere. The PWs in the model that dominate higher up in the MLT region, however, are to a large extent produced by instabilities under the influence of the zonal circulation and temperature variations in the middle atmosphere and they are amplified by GW interactions. Three classes of PWs are generated there. (1) Rossby waves that slowly propagate westward but are carried by the zonal mean (m = 0) winds to produce eastward and westward propagating PWs respectively in the winter and summer hemispheres below 80 km. Depending on the zonal wave number and magnitudes of the zonal winds under the influence of the equatorial oscillations, the PWs typically have periods between 2 and 20 days and their horizontal wind amplitudes can exceed 40 m/s in the lower mesosphere. (2) Rossby gravity waves that propagate westward at low latitudes, having periods around 2 days for zonal wave numbers m = 2 to 4. (3) Eastward propagating equatorial Kelvin waves generated in the upper mesosphere with periods between 2 and 3 days for m = 1 & 2. The seasonal variations of the PWs reveal that the largest wind amplitudes tend to occur below 80 km in the winter hemisphere

Preface to special issue: Layered Phenomena in the Mesopause Region

NASA Astrophysics Data System (ADS)

Chu, Xinzhao; Marsh, Daniel R.

2017-09-01

Historically, the Layered Phenomena in the Mesopause Region (LPMR) workshops have focused on studies of mesospheric clouds and their related science, including spectacular noctilucent clouds (NLCs), polar mesospheric clouds (PMCs), and polar mesospheric summer echoes (PMSEs). This is because, in the pre-technology era, these high-altitude ( 85 km) clouds revealed the existence of substance above the 'normal atmosphere' - our near-space environment is not empty! The occurrence and nature of these clouds have commanded the attention of atmospheric and space scientists for generations. Modern technologies developed in the last 50 years have enabled scientists to significantly advance our understanding of these layered phenomena. Satellite observations expanded these studies to global scales, while lidar and radar observations from the ground enabled fine-scale studies. The launch of the Aeronomy of Ice in the Mesosphere (AIM) satellite in 2007 brought mesospheric cloud research to a more mature level.

A 2D Microphysical Analysis of Aerosol Nucleation in the Polar Winter Stratosphere: Implications for H2SO4 Photolysis and Nucleation Mechanisms

NASA Technical Reports Server (NTRS)

Mills, Michael J.; Toon, Owen B.; Mills, Michael J.; Solomon, Susan

1997-01-01

Each spring a layer of small particles forms between 20 and 30 km in the polar regions. Results are presented from a 2D microphysical model of sulfate aerosol, which provide the first self-consistent explanation of the observed "CN layer." Photochemical conversion of sulfuric acid to SO2 in the upper stratosphere and mesosphere is necessary for this layer to form. Recent laboratory measurements of H2SO4 and SO3 photolysis rates are consistent with such conversion, though an additional source of SO2 may be required. Nucleation throughout the polar winter extends the top of the aerosol layer to higher altitudes, despite strong downward transport of ambient air. This finding may be important to heterogeneous chemistry at the top of the aerosol layer in polar winter and spring.

A cluster ion chemistry for the mesospheric sodium layer

NASA Technical Reports Server (NTRS)

Richter, E. S.; Sechrist, C. F., Jr.

1979-01-01

A cluster ion chemistry for sodium is developed which relates the Na(+) profile to the Na profile using reactions involving Na(+).N2, Na(+).CO2, and Na(+).H2O. Removal of sodium from the mesosphere is accomplished by the formation of higher order clusters of the form Na(+).(H2O)n which presumably precipitate to the lower atmosphere. This sink is most effective in the 80-85 km altitude range. The chemical equilibrium model is applied to experimental observations of the Na and Na(+) layers.

A case study of convectively generated gravity waves coupling of the lower atmosphere and mesosphere-lower thermosphere (MLT) over the tropical region: An observational evidence

NASA Astrophysics Data System (ADS)

Eswaraiah, S.; Venkata Chalapathi, G.; Niranjan Kumar, K.; Venkat Ratnam, M.; Kim, Yong Ha; Vishnu Prasanth, P.; Lee, Jaewook; Rao, S. V. B.

2018-04-01

We have utilized the Gadanki MST Radar and Rayleigh LIDAR to understand the vertical coupling between the lower atmosphere and mesosphere through the short-period gravity waves (GWs). The short-period GWs (20 min-2 h) are noticed both in the troposphere and in the mesosphere during the deep convection. During the convection, the large vertical velocities (>5 m/s) and significant variations in the momentum flux (∼3 m2/s2) are noticed in the troposphere and higher fluxes (∼45 m2/s2) are evidenced in the mesosphere. The observations suggest the vertical coupling between the lower and middle atmosphere during convection.

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

PubMed

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

2016-12-01

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

Mesospheric Temperature Measurements over Scandinavia During the Gravity Wave Life Cycle Campaign (GW-LCYCLE)

NASA Astrophysics Data System (ADS)

Pautet, P. D.; Taylor, M.; Kaifler, B.

2016-12-01

The Gravity Wave Life Cycle (GW-LCYCLE) project took place in Northern Scandinavia during the winter 2015-16. This international program focused on investigating the generation and deep propagation of atmospheric gravity waves, especially the orographic waves generated over the Scandinavian mountain range. A series of instruments was operated at several ground-based locations and on-board the DLR HALO Gulfstream V and Falcon aircrafts. As part of this project, Utah State University (USU) deployed 3 Advanced Mesospheric Temperature Mappers (AMTM) at the ALOMAR facility, Norway (operational since December 2010), at the IRF institute in Kiruna, Sweden, and at the FMI institute in Sodankylä, Finland. Each of these instruments measures the OH (3,1) rotational temperature over a large region (200x160km) at 87km altitude. During the campaign, their total coverage extended across the Scandinavian Mountain Range, from the wind side in the west to 500 km to the east in the lee of the mountains, allowing the investigation of the occurrence and evolution of gravity waves (GWs) over this part of Scandinavia. Furthermore, the AMTM in Sodankylä operated in the container housing a DLR Rayleigh lidar. Both instruments ran simultaneously and autonomously from November 2015 to April 2016, providing an unprecedented complementary high-quality data set. This presentation will introduce preliminary results obtained during this campaign, in particular the evolution of the mesospheric temperature through the winter, the analysis of mountain waves occurrence and dynamics at mesospheric altitude, as well as the investigation of interesting individual GW cases.

Subcritical water extraction of organic matter from sedimentary rocks.

PubMed

Luong, Duy; Sephton, Mark A; Watson, Jonathan S

2015-06-16

Subcritical water extraction of organic matter containing sedimentary rocks at 300°C and 1500 psi produces extracts comparable to conventional solvent extraction. Subcritical water extraction of previously solvent extracted samples confirms that high molecular weight organic matter (kerogen) degradation is not occurring and that only low molecular weight organic matter (free compounds) are being accessed in analogy to solvent extraction procedures. The sedimentary rocks chosen for extraction span the classic geochemical organic matter types. A type I organic matter-containing sedimentary rock produces n-alkanes and isoprenoidal hydrocarbons at 300°C and 1500 psi that indicate an algal source for the organic matter. Extraction of a rock containing type II organic matter at the same temperature and pressure produces aliphatic hydrocarbons but also aromatic compounds reflecting the increased contributions from terrestrial organic matter in this sample. A type III organic matter-containing sample produces a range of non-polar and polar compounds including polycyclic aromatic hydrocarbons and oxygenated aromatic compounds at 300°C and 1500 psi reflecting a dominantly terrestrial origin for the organic materials. Although extraction at 300°C and 1500 psi produces extracts that are comparable to solvent extraction, lower temperature steps display differences related to organic solubility. The type I organic matter produces no products below 300°C and 1500 psi, reflecting its dominantly aliphatic character, while type II and type III organic matter contribute some polar components to the lower temperature steps, reflecting the chemical heterogeneity of their organic inventory. The separation of polar and non-polar organic compounds by using different temperatures provides the potential for selective extraction that may obviate the need for subsequent preparative chromatography steps. Our results indicate that subcritical water extraction can act as a suitable

Six years of mesospheric CO estimated from ground-based frequency-switched microwave radiometry at 57° N compared with satellite instruments

NASA Astrophysics Data System (ADS)

Forkman, P.; Christensen, O. M.; Eriksson, P.; Urban, J.; Funke, B.

2012-11-01

Measurements of mesospheric carbon monoxide, CO, provide important information about the dynamics in the mesosphere region since CO has a long lifetime at these altitudes. Ground-based measurements of mesospheric CO made at the Onsala Space Observatory, OSO, (57° N, 12° E) are presented. The dataset covers the period 2002-2008 and is hence uniquely long for ground-based observations. The simple and stable 115 GHz frequency-switched radiometer, calibration method, retrieval procedure and error characterization are described. A comparison between our measurements and co-located CO measurements from the satellite sensors ACE-FTS on Scisat (v2.2), MLS on Aura (v3-3), MIPAS on Envisat (V3O_CO_12 + 13 and V4O_CO_200) and SMR on Odin (v225 and v021) is carried out. Our instrument, OSO, and the four satellite instruments show the same general variation of the vertical distribution of mesospheric CO in both the annual cycle and in shorter time period events, with high CO mixing ratios during winter and very low amounts during summer in the observed 55-100 km altitude range. During 2004-2008 the agreement of the OSO instrument and the satellite sensors ACE-FTS, MLS and MIPAS (200) is good in the altitude range 55-70 km. Above 70 km, OSO shows up to 25% higher CO column values compared to both ACE and MLS. For the time period 2002-2004, CO from MIPAS (12 + 13) is up to 50% lower than OSO between 55 and 70 km. Mesospheric CO from the two versions of SMR deviates up to ±65% when compared to OSO, but the analysis is based on only a few co-locations.

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.

The validation of ozone measurements from the improved stratospheric and mesospheric sounder

NASA Technical Reports Server (NTRS)

Connor, Brian J.; Scheuer, Christopher J.; Chu, D. A.; Remedios, John J.; Marks, C. J.; Rodgers, Clive D.; Taylor, Fredric W.

1994-01-01

We present preliminary results of the validation of ozone measurements from the Improved Stratospheric and Mesospheric Sounder (ISAMS). The indications are that the ISAMS provides ozone data which generally agrees with other experiments and climatological values, except in regions of large thermal gradients or high aerosol loading. Corrections for these effects will be included in future reprocessing of the data.

Collaborative analysis of Planetary Waves in the Mesospheric Neutral Winds with SuperDARN and TIMED Observations

NASA Astrophysics Data System (ADS)

Ruohoniemi, J. M.

2004-12-01

The SuperDARN HF radars are best known for observing the ExB drift of ionospheric plasma in the high-latitude F region. At mesospheric altitudes the trails of ionization produced by meteors provide another kind of target for radar backscatter, and the motions imparted to these trails by winds in the neutral atmosphere can be measured. In the northern hemisphere the coverage of mesospheric winds currently extends over a 180 deg longitude sector but is confined by propagation conditions to latitudes near 55 deg geographic. We have analyzed several extended periods of simultaneous observations of the neutral wind involving SuperDARN and the TIMED suite of instruments. Often, the winds show clear evidence of large-scale wave events. The quasi 2-day planetary waves are prominent and their occurrence is seen to depend on season. By comparing the wave characteristics between the satellite and ground observations we obtain a complete breakdown of the wave activity in terms of wave periods and zonal wavenumbers. In addition, the semidiurnal tide is a ubiquitous feature of the mid-latitude mesosphere. A single radar station cannot resolve the sun-synchronous component from other contributions at the semidiurnal frequency. We show that with a chain of radars along a latitude band, the true sun-synchronous, or migrating, component can be inferred. Joint analysis can be performed chiefly with data from the SABRE and TIDI instruments.

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

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.

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.

Nighttime mesospheric ozone enhancements during the 2002 southern hemispheric major stratospheric warming

NASA Astrophysics Data System (ADS)

Smith-Johnsen, Christine; Orsolini, Yvan; Stordal, Frode; Limpasuvan, Varavut; Pérot, Kristell

2018-03-01

Sudden Stratospheric Warmings (SSW) affect the chemistry and dynamics of the middle atmosphere. Major warmings occur roughly every second winter in the Northern Hemisphere (NH), but has only been observed once in the Southern Hemisphere (SH), during the Antarctic winter of 2002. Observations by the Global Ozone Monitoring by Occultation of Stars (GOMOS, an instrument on board Envisat) during this rare event, show a 40% increase of ozone in the nighttime secondary ozone layer at subpolar latitudes compared to non-SSW years. This study investigates the cause of the mesospheric nighttime ozone increase, using the National Center for Atmospheric Research (NCAR) Whole Atmosphere Community Climate Model with specified dynamics (SD-WACCM). The 2002 SH winter was characterized by several reductions of the strength of the polar night jet in the upper stratosphere before the jet reversed completely, marking the onset of the major SSW. At the time of these wind reductions, corresponding episodic increases can be seen in the modelled nighttime secondary ozone layer. This ozone increase is attributed largely to enhanced upwelling and the associated cooling of the altitude region in conjunction with the wind reversal. This is in correspondence to similar studies of SSW induced ozone enhancements in NH. But unlike its NH counterpart, the SH secondary ozone layer appeared to be impacted less by episodic variations in atomic hydrogen. Seasonally decreasing atomic hydrogen plays however a larger role in SH compared to NH.

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.

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.

Flight experience of Solar Mesosphere Explorer's two nickel-cadmium batteries

NASA Technical Reports Server (NTRS)

Faber, J.

1985-01-01

The performance of the power system on the solar mesosphere explorer (SME) since launch is discussed. Predictions for continued operation for the rest of the project mission are also discussed. The SME satellite's power system was characterized by both insufficient loading and excessive battery charging during the first year of the mission. These conditions affected battery performance and jeopardized the long-term mission. Increased loading on selected orbits has improved battery performance. Long term projections indicate steadily increasing temperatures for the remainder of the mission.

Large scale atmospheric waves in the Venus mesosphere as seen by the VeRa Radio Science instrument on Venus Express

NASA Astrophysics Data System (ADS)

Tellmann, Silvia; Häusler, Bernd; Hinson, David P.; Tyler, G. Leonard; Andert, Thomas P.; Bird, Michael K.; Imamura, Takeshi; Pätzold, Martin; Remus, Stefan

2015-04-01

Atmospheric waves on all spatial scales play a crucial role in the redistribution of energy, momentum, and atmospheric constituent in planetary atmosphere and are thought to be involved in the development and maintenance of the atmospheric superrotation on Venus. The Venus Express Radio-Science Experiment VeRa sounded the Venus neutral atmosphere and ionosphere in Earth occultation geometry using the spacecraft radio subsystem at two coherent frequencies. Radial profiles of neutral number density, covering the altitude range 40-90 km, are then converted to vertical profiles of temperature and pressure, assuming hydrostatic equilibrium. The extensive VeRa data set enables us to study global scale atmospheric wave phenomena like thermal tides in the mesosphere and troposphere. A pronounced local time dependency of the temperature is found in the mesosphere at different altitude levels. Wave-2 structures dominate the low latitude range in the upper mesosphere while the higher latitudes show a strong wave-1 structure at the top of the cloud layer. The investigation of these wave structures provides valuable information about the energy transport in the atmosphere.

The importance of dynamical feedback on doubled CO{sub 2}-induced changes in the thermal structure of the mesosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Portmann, R.W.; Thomas, G.E.; Solomon, S.

The Garcia-Solomon two-dimensional model was used to study the effect of doubled carbon-dioxide on the middle atmosphere. The model has been improved to include non-LTE CO{sub 2} cooling in the 15 micron band above 70 km and new chemical heating and heating efficiencies. The effect of doubling CO{sub 2} on the temperature is found to be large at the stratopause (about 10-12K cooling) and at the mesopause (about 6-12K cooling). In the stratosphere, dynamical feedbacks on the heating rate caused by the temperature changes are small compared to the radiative changes while in the mesosphere they can be large. Inmore » fact, calculations with the present dynamical heating rate used in the doubled CO{sub 2} energy equation indicate that the radiative forcing alone could cause a temperature increase of about 10K in the polar summer mesopause region. The dynamical feedbacks which oppose this positive radiative forcing are discussed. 18 refs., 3 figs.« less

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.

Vortical susceptibility of finite-density QCD matter

DOE PAGES

Aristova, A.; Frenklakh, D.; Gorsky, A.; ...

2016-10-07

Here, the susceptibility of finite-density QCD matter to vorticity is introduced, as an analog of magnetic susceptibility. It describes the spin polarization of quarks and antiquarks in finite-density QCD matter induced by rotation. We estimate this quantity in the chirally broken phase using the mixed gauge-gravity anomaly at finite baryon density. It is proposed that the vortical susceptibility of QCD matter is responsible for the polarization of Λ and Λ¯ hyperons observed recently in heavy ion collisions at RHIC by the STAR collaboration.

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

A latitudinal survey of mesospheric and upper stratospheric water vapor

NASA Technical Reports Server (NTRS)

Croskey, C. L.; Martone, J. P.; Olivero, J. J.; Puliafito, S. E.

1994-01-01

As part of the LAtitudinal DIstribution of Middle Atmosphere Structure (LADIMAS) campaign, measurements of mesospheric and upper stratospheric water vapor concentration were made over a latitudinal range from 53 N to 63 S. The 22-GHz emission line of water vapor was observed by a new, portable, cryogenically cooled microwave radiometer that was carried on board the German research vessel Polarstern as it sailed from Bremerhaven, Germany, to the Antarctic during November and December, 1991. Water vapor profiles were obtained at approximately 5 deg latitude intervals for an altitude range of 40 to 80 km.

Case Studies of the Mesospheric Response to Recent Minor, Major, and Extended Stratospheric Warmings

DTIC Science & Technology

2010-06-06

Pawson, J. N. Lee , W. H. Daffer, R. A. Fuller, and N. J. Livesey (2009b), Aura Micro- wave Limb Sounder observations of dynamics and transport during...Schoeberl, M., D. Strobel , and J. Apruzese (1983), A numerical model of gravity wave breaking and stress in the mesosphere, J. Geophys. Res., 88(C9

Gravity Wave Dynamics in a Mesospheric Inversion Layer: 1. Reflection, Trapping, and Instability Dynamics

PubMed Central

Laughman, Brian; Wang, Ling; Lund, Thomas S.; Collins, Richard L.

2018-01-01

Abstract An anelastic numerical model is employed to explore the dynamics of gravity waves (GWs) encountering a mesosphere inversion layer (MIL) having a moderate static stability enhancement and a layer of weaker static stability above. Instabilities occur within the MIL when the GW amplitude approaches that required for GW breaking due to compression of the vertical wavelength accompanying the increasing static stability. Thus, MILs can cause large‐amplitude GWs to yield instabilities and turbulence below the altitude where they would otherwise arise. Smaller‐amplitude GWs encountering a MIL do not lead to instability and turbulence but do exhibit partial reflection and transmission, and the transmission is a smaller fraction of the incident GW when instabilities and turbulence arise within the MIL. Additionally, greater GW transmission occurs for weaker MILs and for GWs having larger vertical wavelengths relative to the MIL depth and for lower GW intrinsic frequencies. These results imply similar dynamics for inversions due to other sources, including the tropopause inversion layer, the high stability capping the polar summer mesopause, and lower frequency GWs or tides having sufficient amplitudes to yield significant variations in stability at large and small vertical scales. MILs also imply much stronger reflections and less coherent GW propagation in environments having significant fine structure in the stability and velocity fields than in environments that are smoothly varying. PMID:29576994

Gravity Wave Dynamics in a Mesospheric Inversion Layer: 1. Reflection, Trapping, and Instability Dynamics

NASA Astrophysics Data System (ADS)

Fritts, David C.; Laughman, Brian; Wang, Ling; Lund, Thomas S.; Collins, Richard L.

2018-01-01

An anelastic numerical model is employed to explore the dynamics of gravity waves (GWs) encountering a mesosphere inversion layer (MIL) having a moderate static stability enhancement and a layer of weaker static stability above. Instabilities occur within the MIL when the GW amplitude approaches that required for GW breaking due to compression of the vertical wavelength accompanying the increasing static stability. Thus, MILs can cause large-amplitude GWs to yield instabilities and turbulence below the altitude where they would otherwise arise. Smaller-amplitude GWs encountering a MIL do not lead to instability and turbulence but do exhibit partial reflection and transmission, and the transmission is a smaller fraction of the incident GW when instabilities and turbulence arise within the MIL. Additionally, greater GW transmission occurs for weaker MILs and for GWs having larger vertical wavelengths relative to the MIL depth and for lower GW intrinsic frequencies. These results imply similar dynamics for inversions due to other sources, including the tropopause inversion layer, the high stability capping the polar summer mesopause, and lower frequency GWs or tides having sufficient amplitudes to yield significant variations in stability at large and small vertical scales. MILs also imply much stronger reflections and less coherent GW propagation in environments having significant fine structure in the stability and velocity fields than in environments that are smoothly varying.

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.

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

PubMed

Sulzberger, Barbara; Arey, J Samuel

2016-07-05

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

Response of equatorial and low latitude mesosphere lower thermospheric dynamics to the northern hemispheric sudden stratospheric warming events

NASA Astrophysics Data System (ADS)

Koushik, N.; Kumar, Karanam Kishore; Ramkumar, Geetha; Subrahmanyam, K. V.

2018-04-01

The changes in zonal mean circulation and meridional temperature gradient brought about by Sudden Stratospheric Warming (SSW) events in polar middle atmosphere are found to significantly affect the low latitude counterparts. Several studies have revealed the signatures of SSW events in the low latitude Mesosphere- Lower Thermosphere (MLT) region. Using meteor wind radar observations, the present study investigates the response of semidiurnal oscillations and quasi 2-day waves in the MLT region, simultaneously over low latitude and equatorial stations Thumba (8.5oN, 76.5oE) and Kototabang (0.2oS, 100oE). Unlike many case studies, the present analysis examines the response of low and equatorial latitude MLT region to typical polar stratospheric conditions viz., Quiet winter, Major SSW winter and Minor SSW winter. The present results show that (i) the amplitudes of semidiurnal oscillations and quasi 2-day waves in the equatorial and low latitude MLT region enhance in association with major SSW events, (ii) the semidiurnal oscillations show significant enhancement selectively in the zonal and meridional components over the Northern Hemispheric low latitude and the equatorial stations, respectively (iii) The minor SSW event of January 2012 resulted in anomalously large amplitudes of quasi 2- day waves without any notable increase in the amplitude of semidiurnal oscillations. The significance of the present study lies in comprehensively bringing out the signatures of SSW events in the semidiurnal oscillations and quasi 2-day waves in low latitude and equatorial MLT region, simultaneously for the first time over these latitudes.

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.

The double seismic zone in downgoing slabs and the viscosity of the mesosphere

NASA Technical Reports Server (NTRS)

Sleep, N. H.

1979-01-01

The seismic zone beneath several island arcs between about 100 and 200 km depth consists of an upper zone having down-dip compression and a lower zone having down-dip tension. Several numerical models of the Aleutian arc were computed to test the hypothesis that these double seismic zones are due to sagging of the slab under its own weight. This sagging occurs because the asthenosphere (between about 100 and 200 km) provides little support or resistance to the slab, which is supported from below by the more viscous mesosphere and from above by the lithosphere. The viscosity of the mesosphere was constrained to the interval between 0.25 x 10 to the 22nd and 0.5 x 10 to the 22nd P by noting that the slab would have mainly down-dip compression at higher viscosities and mainly down-dip tension at lower viscosities. The deviatoric stress in the slab and the fault plane between the slab and the island arc is about 200-300 bars (expressed as shear stress). The models were calibrated to the observed depth and gravity anomalies in the trench.

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.

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

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.

An all-reflective polarization rotator

NASA Astrophysics Data System (ADS)

Bohus, J.; Budai, Judit; Kalashnikov, M.; Osvay, K.

2017-05-01

The conceptual design and proof of principle experimental results of a polarization rotator based on mirrors are presented. The device is suitable for any-angle, online rotation of the plane of polarization of high peak intensity ultrashort laser pulses. Controllable rotation of the polarization vector of short laser pulses with a broad bandwidth requires achromatic retarding plates which have a limited scalability and the substantial plate thickness can lead to pulse broadening and inaccurate polarization rotation. Polarization rotators based on reflective optical elements are preferable alternatives to wave plates especially when used in high average power or high peak intensity ultra-short laser systems. The control of the polarization state is desirable in many laser-matter interaction experiments e.g., high harmonic and attosecond pulse generation, electron, proton and ion acceleration, electron-positron pair creating, vacuum nonlinear polarization effect. The device can also serve as a beam attenuator, in combination with a linear polarizer.

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.

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 No.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

Validation of the MIPAS CO2 volume mixing ratio in the mesosphere and lower thermosphere and comparison with WACCM simulations

NASA Astrophysics Data System (ADS)

López-Puertas, Manuel; Funke, B.; Jurado-Navarro, Á. A.; García-Comas, M.; Gardini, A.; Boone, C. D.; Rezac, L.; Garcia, R. R.

2017-08-01

We present the validation of Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) CO2 daytime concentration in the mesosphere and lower thermosphere by comparing with Atmospheric Chemistry Experiment (ACE) Fourier transform spectrometer and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) data. MIPAS shows a very good agreement with ACE below 100 km with differences of ˜5%. Above 100 km, MIPAS CO2 is generally lower than ACE with differences growing from ˜5% at 100 km to 20-40% near 110-120 km. Part of this disagreement can be explained by the lack of a nonlocal thermodynamic equilibrium correction in ACE. MIPAS also agrees very well (˜5%) with SABER below 100 km. At 90-105 km, MIPAS is generally smaller than SABER by 10-30% in the polar summers. At 100-120 km, MIPAS and SABER CO2 agree within ˜10% during equinox but, for solstice, MIPAS is larger by 10-25%, except near the polar summer. Whole Atmosphere Community Climate Model (WACCM) CO2 shows the major MIPAS features. At 75-100 km, the agreement is very good (˜5%), with maximum differences of ˜10%. At 95-115 km MIPAS CO2 is larger than WACCM by 20-30% in the winter hemisphere but smaller (20-40%) in the summer. Above 95-100 km WACCM generally overestimates MIPAS CO2 by about 20-80% except in the polar summer where underestimates it by 20-40%. MIPAS CO2 favors a large eddy diffusion below 100 km and suggests that the meridional circulation of the lower thermosphere is stronger than in WACCM. The three instruments and WACCM show a clear increase of CO2 with time, more markedly at 90-100 km.

The Evolution of the Stratopause during the 2006 Major Warming: Satellite Data and Assimilated Meteorological Analyses

NASA Technical Reports Server (NTRS)

Manney, Gloria L.; Krueger, Kirstin; Pawson, Steven; Minschwaner, Ken; Schwartz, Michael J.; Daffer, William H.; Livesey, Nathaniel J.; Mlynczak, Martin G.; Remsberg, Ellis E.; Russell, James M., III;

Characterization of polar organics in airborne particulate matter

NASA Astrophysics Data System (ADS)

Yokouchi, Y.; Ambe, Y.

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

Tropical behavior of mesospheric ozone as observed by SMM

NASA Technical Reports Server (NTRS)

Aikin, A. C.; Kendig, D. J.

1992-01-01

The seasonal behavior of low latitude mesospheric ozone, as observed by the SMM satellite solar occultation experiment, is detailed for the 1985-1989 period. Annual as well as semi-annual waves are observed in the 50-70 km altitude region. In the latitude range of +/- 30 deg the ozone phase and amplitude are functions of temperature and seasonal changes in solar flux. Temperature is the controlling factor for the equatorial region and seasonal changes in solar flux become more dominant at latitudes outside the equatorial zone (greater than +/- 15 deg). There is a hemispheric asymmetry in the ozone annual wave in the 20-30 deg region, with Northern Hemispheric ozone having a larger amplitude than Southern Hemispheric ozone.

Polarization in Nanophotonics

NASA Astrophysics Data System (ADS)

Mueller, Jan Philipp Balthasar

In the last three or so decades, optical scientists have begun to capitalize in earnest on the advances in nanofabrication that is owed to the explosive rise of miniaturized semiconductor electronics. The resulting field, nanophotonics, has opened a vast design space for applied researchers and required revisiting some of the oldest problems and assumptions of optical physics. Polarization, meaning, in the context of light, the direction of oscillation of the electromagnetic field in space, is a particularly malleable property of light that can be used to shape and direct wave fronts, to measure and control light-matter interactions, and to encode information. It remains an underexplored and underutilized feature of nature, though the new methods of nanophotonics can harness its potential to a much greater extent than any previous optical technology platform. This thesis explores some aspects of the role light's polarization plays at the interface of optics and nanotechnology. In particular, it will touch upon the way polarization may be used to control the generation of optical nearfields, how the polarization structure of evanescent waves leads to unusual optical forces, and how nanoscale polarization-transformations enable a new class of polarization-sensitive optical elements. It will also show how nanophotonics may address the problem of measuring polarization based on a new polarimeter architecture.

Characteristics of 3-D transport simulations of the stratosphere and mesosphere

NASA Technical Reports Server (NTRS)

Fairlie, T. D. A.; Siskind, D. E.; Turner, R. E.; Fisher, M.

1992-01-01

A 3D mechanistic, primitive-equation model of the stratosphere and mesosphere is coupled to an offline spectral transport model. The dynamics model is initialized with and forced by observations so that the coupled models may be used to study specific episodes. Results are compared with those obtained by transport online in the dynamics model. Although some differences are apparent, the results suggest that coupling of the models to a comprehensive photochemical package will provide a useful tool for studying the evolution of constituents in the middle atmosphere during specific episodes.

Vertical propagation of information in a middle atmosphere data assimilation system by gravity-wave drag feedbacks

NASA Astrophysics Data System (ADS)

Ren, Shuzhan; Polavarapu, Saroja M.; Shepherd, Theodore G.

2008-03-01

The mesospheric response to the 2002 Antarctic Stratospheric Sudden Warming (SSW) is analysed using the Canadian Middle Atmosphere Model Data Assimilation System (CMAM-DAS), where it represents a vertical propagation of information from the observations into the data-free mesosphere. The CMAM-DAS simulates a cooling in the lowest part of the mesosphere which is accomplished by resolved motions, but which is extended to the mid- to upper mesosphere by the response of the model's non-orographic gravity-wave drag parameterization to the change in zonal winds. The basic mechanism is that elucidated by Holton consisting of a net eastward wave-drag anomaly in the mesosphere during the SSW, although in this case there is a net upwelling in the polar mesosphere. Since the zonal-mean mesospheric response is shown to be predictable, this demonstrates that variations in the mesospheric state can be slaved to the lower atmosphere through gravity-wave drag.

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

NASA Astrophysics Data System (ADS)

Aoki, S.; Sato, Y.; Giuranna, M.; Wolkenberg, P.; Sato, T. M.; Nakagawa, H.; Kasaba, Y.

2018-03-01

We have investigated mesospheric CO2 ice clouds on Mars through analysis of near-infrared spectra acquired by Planetary Fourier Spectrometer (PFS) onboard the Mars Express (MEx) from MY 27 to MY 32. With the highest spectral resolution achieved thus far in the relevant spectral range among remote-sensing experiments orbiting Mars, PFS enables precise identification of the scattering peak of CO2 ice at the bottom of the 4.3 μm CO2 band. A total of 111 occurrences of CO2 ice cloud features have been detected over the period investigated. Data from the OMEGA imaging spectrometer onboard MEx confirm all of PFS detections from times when OMEGA operated simultaneously with PFS. The spatial and seasonal distributions of the CO2 ice clouds detected by PFS are consistent with previous observations by other instruments. We find CO2 ice clouds between Ls = 0° and 140° in distinct longitudinal corridors around the equatorial region (± 20°N). Moreover, CO2 ice clouds were preferentially detected at the observational LT range between 15-16 h in MY 29. However, observational biases prevent from distinguishing local time dependency from inter-annual variation. PFS also enables us to investigate the shape of mesospheric CO2 ice cloud spectral features in detail. In all cases, peaks were found between 4.240 and 4.265 μm. Relatively small secondary peaks were occasionally observed around 4.28 μm (8 occurrences). These spectral features cannot be reproduced using our radiative transfer model, which may be because the available CO2 ice refractive indices are inappropriate for the mesospheric temperatures of Mars, or because of the assumption in our model that the CO2 ice crystals are spherical and composed by pure CO2 ice.

A rocket-borne mass analyzer for charged aerosol particles in the mesosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knappmiller, Scott; Robertson, Scott; Sternovsky, Zoltan

2008-10-15

An electrostatic mass spectrometer for nanometer-sized charged aerosol particles in the mesosphere has been developed and tested. The analyzer is mounted on the forward end of a rocket and has a slit opening for admitting a continuous sample of air that is exhausted through ports at the sides. Within the instrument housing are two sets of four collection plates that are biased with positive and negative voltages for the collection of negative and positive aerosol particles, respectively. Each collection plate spans about an order of magnitude in mass which corresponds to a factor of 2 in radius. The number densitymore » of the charge is calculated from the current collected by the plates. The mean free path for molecular collisions in the mesosphere is comparable to the size of the instrument opening; thus, the analyzer performance is modeled by a Monte Carlo computer code that finds the aerosol particles trajectories within the instrument including both the electrostatic force and the forces from collisions of the aerosol particles with air molecules. Mass sensitivity curves obtained using the computer models are near to those obtained in the laboratory using an ion source. The first two flights of the instrument returned data showing the charge number densities of both positive and negative aerosol particles in four mass ranges.« less

Observations of the 10-micron natural laser emission from the mesospheres of Mars and Venus

NASA Technical Reports Server (NTRS)

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

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 percent 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.

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.

Three-dimensional orientation-unlimited polarization encryption by a single optically configured vectorial beam.

PubMed

Li, Xiangping; Lan, Tzu-Hsiang; Tien, Chung-Hao; Gu, Min

2012-01-01

The interplay between light polarization and matter is the basis of many fundamental physical processes and applications. However, the electromagnetic wave nature of light in free space sets a fundamental limit on the three-dimensional polarization orientation of a light beam. Although a high numerical aperture objective can be used to bend the wavefront of a radially polarized beam to generate the longitudinal polarization state in the focal volume, the arbitrary three-dimensional polarization orientation of a beam has not been achieved yet. Here we present a novel technique for generating arbitrary three-dimensional polarization orientation by a single optically configured vectorial beam. As a consequence, by applying this technique to gold nanorods, orientation-unlimited polarization encryption with ultra-security is demonstrated. These results represent a new landmark of the orientation-unlimited three-dimensional polarization control of the light-matter interaction.

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.

The polar-ring galaxies NGC 2685 and NGC 3808B (VV 300)

NASA Technical Reports Server (NTRS)

Reshetnikov, V. P.; Yakovleva, V. A.

1990-01-01

Polar-ring galaxies (PRG) are among the most interesting examples of interaction between galaxies. A PRG is a galaxy with an elongated main body surrounded by a ring (or a disk) of stars, gas, and dust rotating in a near-polar plane (Schweizer, Whitmore, and Rubin, 1983). Accretion of matter by a massive lenticular galaxy from either intergalactic medium or a companion galaxy is usually considered as an explanation of the observed structure of PRG. In the latter case there are two possibilities: capture and merging of a neighbor galaxy, and accretion of mass from a companion galaxy during a close encounter. Two PRG formation scenarios just mentioned are illustrated here by the results of our observations of the peculiar galaxies NGC 2685 and NGC 3808B.

Earth Observations taken by Expedition 34 crewmember

NASA Image and Video Library

2013-01-05

ISS034-E-024622 (5 Jan. 2013) --- Polar mesospheric clouds over the South Pacific Ocean are featured in this image photographed by an Expedition 34 crew member on the International Space Station. Polar mesospheric clouds—also known as noctilucent, or “night shining” clouds—are formed 76 to 85 kilometers above Earth’s surface near the mesosphere-thermosphere boundary of the atmosphere, a region known as the mesopause. At these altitudes, water vapor can freeze into clouds of ice crystals. When the sun is below the horizon such that the ground is in darkness, these high clouds may still be illuminated—lending them their ethereal, “night shining” qualities. Noctilucent clouds have been observed from all human vantage points in both the Northern and Southern Hemispheres – from the surface, in aircraft, and in orbit from the space station—and tend to be most visible during the late spring and early summer seasons. Polar mesospheric clouds also are of interest to scientists studying the atmosphere. While some scientists seek to understand their mechanisms of formation, others have identified them as potential indicators of atmospheric changes resulting from increases in greenhouse gas concentrations. This photograph was taken when the station was over the Pacific Ocean south of French Polynesia. While most polar mesospheric cloud images are taken from the orbital complex with relatively short focal length lens to maximize the field of view, this image was taken with a long lens (400 mm) allowing for additional detail of the cloud forms to be seen. Below the brightly-lit noctilucent clouds in the center of the image, the pale orange band indicates the stratosphere.

Spin-analyzed SANS for soft matter applications

NASA Astrophysics Data System (ADS)

Chen, W. C.; Barker, J. G.; Jones, R.; Krycka, K. L.; Watson, S. M.; Gagnon, C.; Perevozchivoka, T.; Butler, P.; Gentile, T. R.

2017-06-01

The small angle neutron scattering (SANS) of nearly Q-independent nuclear spin-incoherent scattering from hydrogen present in most soft matter and biology samples may raise an issue in structure determination in certain soft matter applications. This is true at high wave vector transfer Q where coherent scattering is much weaker than the nearly Q-independent spin-incoherent scattering background. Polarization analysis is capable of separating coherent scattering from spin-incoherent scattering, hence potentially removing the nearly Q-independent background. Here we demonstrate SANS polarization analysis in conjunction with the time-of-flight technique for separation of coherent and nuclear spin-incoherent scattering for a sample of silver behenate back-filled with light water. We describe a complete procedure for SANS polarization analysis for separating coherent from incoherent scattering for soft matter samples that show inelastic scattering. Polarization efficiency correction and subsequent separation of the coherent and incoherent scattering have been done with and without a time-of-flight technique for direct comparisons. In addition, we have accounted for the effect of multiple scattering from light water to determine the contribution of nuclear spin-incoherent scattering in both the spin flip channel and non-spin flip channel when performing SANS polarization analysis. We discuss the possible gain in the signal-to-noise ratio for the measured coherent scattering signal using polarization analysis with the time-of-flight technique compared with routine unpolarized SANS measurements.

Many-particle theory of nuclear systems with application to neutron star matter

NASA Technical Reports Server (NTRS)

Chakkalakal, D. A.; Yang, C.

1973-01-01

The research is reported concerning energy-density relation for the normal state of neutron star matter, and the effects of superfluidity and polarization on neutron star matter. Considering constraints on variation, and the theory of quantum fluids, three methods for calculating the energy-density range are presented. The effects of polarization on neutron star structure, and polarization effects on condensation and superfluid-state energy are discussed.

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.

Laboratory Investigations of Mesospheric Ice Surfaces: Absence of Dangling Bonds in the Presence of Atomic Oxygen

NASA Astrophysics Data System (ADS)

Boulter, J. E.; Morgan, C. G.; Marschall, J.

2006-05-01

Remote observations of PMCs have become more sophisticated and have increased in geographic and temporal coverage, while numerical models have advanced in detail and predictive power. Together, these advances enable new questions of PMC morphology, optical properties, and microphysical processes in their formation and dissipation. Laboratory investigations also advance this understanding, simulating physical and chemical processes unique to this atmospheric region under comparable conditions. In this work, ice deposition experiments in the presence of microwave discharge-dissociated molecular oxygen suggest heterogeneous interactions between dangling OH bonds on the ice surface and atomic oxygen. Ice films deposited on a gold substrate at temperatures of 115, 130, and 140 K from oxygen/water gas mixtures representative of the summertime polar mesosphere exhibit infrared absorption features characteristic of dangling bonds, whereas films grown in the presence of atomic oxygen do not. Dangling bond spectral features are shown to diminish rapidly when the microwave discharge is activated during ice deposition. Similar decreases were not seen when the gas stream was heated or when the ice film was slowly annealed from 130 to 160 K. One interpretation of these results is that atomic oxygen binds to dangling bond sites during ice growth, a phenomenon that may also occur during the formation of ice particles observed just below the cold summertime mesopause.

New insights for mesospheric OH: multi-quantum vibrational relaxation as a driver for non-local thermodynamic equilibrium

PubMed Central

Kalogerakis, Konstantinos S.; Matsiev, Daniel; Cosby, Philip C.; Dodd, James A.; Falcinelli, Stefano; Hedin, Jonas; Kutepov, Alexander A.; Noll, Stefan; Panka, Peter A.; Romanescu, Constantin; Thiebaud, Jérôme E.

2018-01-01

The question of whether mesospheric OH(υ) rotational population distributions are in equilibrium with the local kinetic temperature has been debated over several decades. Despite several indications for the existence of non-equilibrium effects, the general consensus has been that emissions originating from low rotational levels are thermalized. Sky spectra simultaneously observing several vibrational levels demonstrated reproducible trends in the extracted OH(υ) rotational temperatures as a function of vibrational excitation. Laboratory experiments provided information on rotational energy transfer and direct evidence for fast multi-quantum OH(high-υ) vibrational relaxation by O atoms. We examine the relationship of the new relaxation pathways with the behavior exhibited by OH(υ) rotational population distributions. Rapid OH(high-υ) + O multi-quantum vibrational relaxation connects high and low vibrational levels and enhances the hot tail of the OH(low-υ) rotational distributions. The effective rotational temperatures of mesospheric OH(υ) are found to deviate from local thermodynamic equilibrium for all observed vibrational levels. PMID:29503514

A stationary phase solution for mountain waves with application to mesospheric mountain waves generated by Auckland Island

NASA Astrophysics Data System (ADS)

Broutman, Dave; Eckermann, Stephen D.; Knight, Harold; Ma, Jun

2017-01-01

A relatively general stationary phase solution is derived for mountain waves from localized topography. It applies to hydrostatic, nonhydrostatic, or anelastic dispersion relations, to arbitrary localized topography, and to arbitrary smooth vertically varying background temperature and vector wind profiles. A simple method is introduced to compute the ray Jacobian that quantifies the effects of horizontal geometrical spreading in the stationary phase solution. The stationary phase solution is applied to mesospheric mountain waves generated by Auckland Island during the Deep Propagating Gravity Wave Experiment. The results are compared to a Fourier solution. The emphasis is on interpretations involving horizontal geometrical spreading. The results show larger horizontal geometrical spreading for nonhydrostatic waves than for hydrostatic waves in the region directly above the island; the dominant effect of horizontal geometrical spreading in the lower ˜30 km of the atmosphere, compared to the effects of refraction and background density variation; and the enhanced geometrical spreading due to directional wind in the approach to a critical layer in the mesosphere.

Retrieval of O2(1Σ) and O2(1Δ) volume emission rates in the mesosphere and lower thermosphere using SCIAMACHY MLT limb scans

NASA Astrophysics Data System (ADS)

Zarboo, Amirmahdi; Bender, Stefan; Burrows, John P.; Orphal, Johannes; Sinnhuber, Miriam

2018-01-01

We present the retrieved volume emission rates (VERs) from the airglow of both the daytime and twilight O2(1Σ) band and O2(1Δ) band emissions in the mesosphere and lower thermosphere (MLT). The SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIAMACHY) onboard the European Space Agency Envisat satellite observes upwelling radiances in limb-viewing geometry during its special MLT mode over the range 50-150 km. In this study we use the limb observations in the visible (595-811 nm) and near-infrared (1200-1360 nm) bands. We have investigated the daily mean latitudinal distributions and the time series of the retrieved VER in the altitude range from 53 to 149 km. The maximal observed VERs of O2(1Δ) during daytime are typically 1 to 2 orders of magnitude larger than those of O2(1Σ). The latter peaks at around 90 km, whereas the O2(1Δ) emissivity decreases with altitude, with the largest values at the lower edge of the observations (about 53 km). The VER values in the upper mesosphere (above 80 km) are found to depend on the position of the sun, with pronounced high values occurring during summer for O2(1Δ). O2(1Σ) emissions show additional high values at polar latitudes during winter and spring. These additional high values are presumably related to the downwelling of atomic oxygen after large sudden stratospheric warmings (SSWs). Accurate measurements of the O2(1Σ) and O2(1Δ) airglow, provided that the mechanism of their production is understood, yield valuable information about both the chemistry and dynamics in the MLT. For example, they can be used to infer the amounts and distribution of ozone, solar heating rates, and temperature in the MLT.

Laboratory measurements of heterogeneous CO2 ice nucleation on nanoparticles under conditions relevant to the Martian mesosphere

NASA Astrophysics Data System (ADS)

Nachbar, Mario; Duft, Denis; Mangan, Thomas Peter; Martin, Juan Carlos Gomez; Plane, John M. C.; Leisner, Thomas

2016-05-01

Clouds of CO2 ice particles have been observed in the Martian mesosphere. These clouds are believed to be formed through heterogeneous nucleation of CO2 on nanometer-sized meteoric smoke particles (MSPs) or upward propagated Martian dust particles (MDPs). Large uncertainties still exist in parameterizing the microphysical formation process of these clouds as key physicochemical parameters are not well known. We present measurements on the nucleation and growth of CO2 ice on sub-4 nm radius iron oxide and silica particles representing MSPs at conditions close to the mesosphere of Mars. For both particle materials we determine the desorption energy of CO2 to be ΔFdes = (18.5 ± 0.2) kJ mol-1 corresponding to ΔFdes = (0.192 ± 0.002) eV and obtain m = 0.78 ± 0.02 for the contact parameter that governs heterogeneous nucleation by analyzing the measurements using classical heterogeneous nucleation theory. We did not find any temperature dependence for the contact parameter in the temperature range examined (64 K to 73 K). By applying these values for MSPs in the Martian mesosphere, we derive characteristic temperatures for the onset of CO2 ice nucleation, which are 8-18 K below the CO2 frost point temperature, depending on particle size. This is in line with the occurrence of highly supersaturated conditions extending to 20 K below frost point temperature without the observation of clouds. Moreover, the sticking coefficient of CO2 on solid CO2 was determined to be near unity. We further argue that the same parameters can be applied to CO2 nucleation on upward propagated MDPs.

Inter-Hemispheric Coupling During Northern Polar Summer Periods of 2002-2010 using TIMED/SABER Measurements

NASA Technical Reports Server (NTRS)

Goldberg, Richard A.; Feofilov, A. G.; Pesnell, W. D.; Kutepov, A. A.

2012-01-01

It has been found that for more than one polar summer season between 2002-2010, the northern polar mesospheric region near and above about 80 km was warmer than normal. The strongest warming effect of this type was observed to occur during northern summer 2002. Theoretical studies have implied that these "anomalies" were preceded by unusual dynamical processes in the southern hemisphere. We have analyzed temperature distributions measured by the SABER limb scanning infrared radiometer aboard the NASA TIMED satellite between 2002-2010 at altitudes from 15 to 110 km and for latitudes between 83 S to 83 N. We describe the approach to trace the inter-hemispheric temperature correlations demonstrating the global features that were unique for the "anomalous" northern polar summers. From our analysis of SABER data from 2002-2010, the anomalous heating for the northern mesopause region during northern summer was accompanied by stratospheric heating in the equatorial region. In the winter hemisphere it is accompanied by heating in the lower stratosphere and mesopause region, and cooling in the stratopause region. Also, all the elements of the temperature anomaly structure appear to develop and fade away nearly simultaneously, thereby suggesting either a global influence or a rapid exchange.

Measurement of the cosmic microwave background polarization lensing power spectrum with the POLARBEAR experiment.

PubMed

Ade, P A R; Akiba, Y; Anthony, A E; Arnold, K; Atlas, M; Barron, D; Boettger, D; Borrill, J; Chapman, S; Chinone, Y; Dobbs, M; Elleflot, T; Errard, J; Fabbian, G; Feng, C; Flanigan, D; Gilbert, A; Grainger, W; Halverson, N W; Hasegawa, M; Hattori, K; Hazumi, M; Holzapfel, W L; Hori, Y; Howard, J; Hyland, P; Inoue, Y; Jaehnig, G C; Jaffe, A; Keating, B; Kermish, Z; Keskitalo, R; Kisner, T; Le Jeune, M; Lee, A T; Linder, E; Leitch, E M; Lungu, M; Matsuda, F; Matsumura, T; Meng, X; Miller, N J; Morii, H; Moyerman, S; Myers, M J; Navaroli, M; Nishino, H; Paar, H; Peloton, J; Quealy, E; Rebeiz, G; Reichardt, C L; Richards, P L; Ross, C; Schanning, I; Schenck, D E; Sherwin, B; Shimizu, A; Shimmin, C; Shimon, M; Siritanasak, P; Smecher, G; Spieler, H; Stebor, N; Steinbach, B; Stompor, R; Suzuki, A; Takakura, S; Tomaru, T; Wilson, B; Yadav, A; Zahn, O

2014-07-11

Gravitational lensing due to the large-scale distribution of matter in the cosmos distorts the primordial cosmic microwave background (CMB) and thereby induces new, small-scale B-mode polarization. This signal carries detailed information about the distribution of all the gravitating matter between the observer and CMB last scattering surface. We report the first direct evidence for polarization lensing based on purely CMB information, from using the four-point correlations of even- and odd-parity E- and B-mode polarization mapped over ∼30 square degrees of the sky measured by the POLARBEAR experiment. These data were analyzed using a blind analysis framework and checked for spurious systematic contamination using null tests and simulations. Evidence for the signal of polarization lensing and lensing B modes is found at 4.2σ (stat+sys) significance. The amplitude of matter fluctuations is measured with a precision of 27%, and is found to be consistent with the Lambda cold dark matter cosmological model. This measurement demonstrates a new technique, capable of mapping all gravitating matter in the Universe, sensitive to the sum of neutrino masses, and essential for cleaning the lensing B-mode signal in searches for primordial gravitational waves.

Measurements of the structure and circulation of the stratosphere and mesosphere, 1970

NASA Technical Reports Server (NTRS)

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

1972-01-01

Complete data from a total of 26 meteorological rocket soundings of the stratosphere and mesosphere conducted from Barrow, Alaska; Churchill, Canada; and Wallops Island, Va., are presented. These data consist of temperature, pressure, density, and wind profiles from 16 acoustic grenade soundings that cover the 30- to 90-km altitude range, and temperature, pressure, and density profiles from 10 pitot probe soundings that cover the 25- to 120-km altitude range. Errors for each of the 16 grenade soundings are also included. No analysis of the meteorological significance of the data is attempted.

NASA Aims to Create First-Ever Space-Based Sodium Lidar to Study Poorly Understood Mesosphere

NASA Image and Video Library

2017-12-08

Caption: Mike Krainak (left) and Diego Janches recently won NASA follow-on funding to advance a spaceborne sodium lidar needed to probe Earth’s poorly understood mesosphere. Credits: NASA/W. Hrybyk More: A team of NASA scientists and engineers now believes it can leverage recent advances in a greenhouse-detecting instrument to build the world’s first space-based sodium lidar to study Earth’s poorly understood mesosphere. Scientist Diego Janches and laser experts Mike Krainak and Tony Yu, all of whom work at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, are leading a research-and-development effort to further advance the sodium lidar, which the group plans to deploy on the International Space Station if it succeeds in proving its flightworthiness. Read more: go.nasa.gov/2rcGpSM NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

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.

Polar Northern Hemisphere Middle Atmospheric Influence due to Energetic Particle Precipitation in January 2005

NASA Technical Reports Server (NTRS)

Jackman, Charles H.

2010-01-01

Solar eruptions and geomagnetic activity led to energetic particle precipitation in early 2005, primarily during the January 16-21 period. Production of OH and destruction of ozone have been documented due to the enhanced energetic solar proton flux in January 2005 [e.g., Verronen et al., Geophys. Res. Lett.,33,L24811,doi:10.1029/2006GL028115, 2006; Seppala et al., Geophys. Res. Lett.,33,L07804, doi:10.1029/2005GL025571,2006]. These solar protons as well as precipitating electrons also led to the production of NO(x) (NO, NO2). Our simulations with the Whole Atmosphere Community Climate Model (WACCM) show that NO(x) is enhanced by 20-50 ppbv in the polar Northern Hemisphere middle mesosphere (approx.60-70 km) by January 18. Both the SCISAT-1 Atmospheric Chemistry Experiment (ACE) NO(x) measurements and Envisat Michelson Interferometer for Passive Atmospheric Sounding (MIP AS) nighttime NO2 observations show large increases during this period, in reasonable agreement with WACCM predictions. Such enhancements are considerable for the mesosphere and led to simulated increases in polar Northern Hemisphere upper stratospheric odd nitrogen (NO(y)) of2-5 ppbv into February 2005. The largest ground level enhancement (GLE) of solar cycle 23 occurred on January 20, 2005 with a neutron monitor increase of about 270 percent [Gopalswamy et al., 29th International Cosmic Ray Conference, Pune,00,101-104,2005]. We found that protons of energies 300 to 20,000 MeV, not normally included in our computations, led to enhanced stratospheric NO(y) of less than 1 percent as a result of this GLE. The atmospheric impact of precipitating middle energy electrons (30-2,500 keV) during the January 16-21, 2005 period is also of interest, and an effort is ongoing to include these in WACCM computations. This presentation will show both short- and longer-term changes due to the January 2005 energetic particle precipitation.

Unveiling Mars nightside mesosphere dynamics by IUVS/MAVEN global images of NO nightglow

NASA Astrophysics Data System (ADS)

Stiepen, A.; Jain, S. K.; Schneider, N. M.; Milby, Z.; Deighan, J. I.; Gonzàlez-Galindo, F.; Gérard, J.-C.; Forget, F.; Bougher, S.; Stewart, A. I. F.; Royer, E.; Stevens, M. H.; Evans, J. S.; Chaffin, M. S.; Crismani, M.; McClintock, W. E.; Clarke, J. T.; Holsclaw, G. W.; Montmessin, F.; Lo, D. Y.

2017-09-01

We analyze the morphology of the ultraviolet nightglow in the Martian upper atmosphere through Nitric Oxide (NO) δ and γ bands emissions observed by the Imaging Ultraviolet Spectrograph instrument on the Mars Atmosphere and Volatile EvolutioN spacecraft. The seasonal dynamics of the Martian thermosphere-mesosphere can be constrained based on the distribution of these emissions. We show evidence for local (emission streaks and splotches) and global (longitudinal and seasonal) variability in brightness of the emission and provide quantitative comparisons to GCM simulations.

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.

Mesospheric temperatures estimated from the meteor radar observations at Mohe, China

NASA Astrophysics Data System (ADS)

Liu, Libo; Liu, Huixin; Le, Huijun; Chen, Yiding; Sun, Yang-Yi; Ning, Baiqi; Hu, Lianhuan; Wan, Weixing; Li, Na; Xiong, Jiangang

2017-02-01

In this work, we report the estimation of mesospheric temperatures at 90 km height from the observations of the VHF all-sky meteor radar operated at Mohe (53.5°N, 122.3°E), China, since August 2011. The kinetic temperature profiles retrieved from the observations of Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) on board the Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics satellite are processed to provide the temperature (TSABER) and temperature gradient (dT/dh) at 90 km height. Based on the SABER temperature profile data an empirical dT/dh model is developed for the Mohe latitude. First, we derive the temperatures from the meteor decay times (Tmeteor) and the Mohe dT/dh model gives prior information of temperature gradients. Second, the full width at half maximum (FWHM) of the meteor height profiles is calculated and further used to deduce the temperatures (TFWHM) based on the strong linear relationship between FWHM and TSABER. The temperatures at 90 km deduced from the decay times (Tmeteor) and from the meteor height distributions (TFWHM) at Mohe are validated/calibrated with TSABER. The temperatures present a considerable annual variation, being maximum in winter and minimum in summer. Harmonic analyses reveal that the temperatures have an annual variation consistent with TSABER. Our work suggests that FWHM has a good performance in routine estimation of the temperatures. It should be pointed out that the slope of FWHM as a function of TSABER is 10.1 at Mohe, which is different from that of 15.71 at King Sejong (62.2°S, 58.8°E) station.

The Effect of the Madden-Julian Oscillation on the Mesospheric Migrating Diurnal Tide: A Study Using SD-WACCM

NASA Astrophysics Data System (ADS)

Yang, Chengyun; Smith, Anne K.; Li, Tao; Dou, Xiankang

2018-05-01

The response of the mesospheric migrating diurnal (DW1) tide to the Madden-Julian oscillation (MJO) is investigated for the first time using a simulation from the Specified-Dynamic Whole Atmosphere Community Climate Model (SD-WACCM), which is driven by reanalysis data. Analysis shows that a significant connection exists between the MJO and the mesospheric DW1 tidal amplitude. During MJO phases 2 and 3, the convection anomalies are associated with enhancement in both the solar insolation absorption and latent heat release in the equatorial troposphere; these in turn lead to stronger DW1 forcing. Conversely, the forcing of DW1 by solar and latent heating in the troposphere is weaker during MJO phase 8. The difference of the tidal amplitude during the opposite MJO phases from the boreal winter mean state is 15-20%. The parameterized gravity wave variations are found to have a significant impact on the DW1 tidal response in some phases of the MJO.

Microwave Observations and Modeling of O2 (1-delta(sub g)) and O3 Diurnal Variation in the Mesosphere

NASA Technical Reports Server (NTRS)

Sandor, Brad J.; Clancy, R. Todd; Rusch, David W.; Randall, Cora E.; Eckman, Richard S.; Siskind, David S.; Muhleman, Duane O.

1997-01-01

The first microwave measurements of an electronically excited molecular species in the Earth's atmosphere are presented. Local thermodynamic equilibrium (LTE) rotational line emission from mesospheric O2(1-del(sub g)) was observed at a frequency of 255.01794 GHz (lambda is approx. 1.2 mm), employing the National Radio Astronomy Observatory (NRAO) millimeter facility at Kitt Peak, Arizona (32 N, 111 W). The pressure broadened line shapes of the O2(1-del(sub g)) spectra, which were obtained in January and April 1992 and in January and November 1993, are inverted to retrieve O2(1-del(sub g)) mixing profiles over the 50-70 km altitude region. The observed daytime abundances exceed ozone abundances in the lower mesosphere, which are separately retrieved with coincident O3 spectral line (249.7886 GHz) observations. The January and November 1993 observations are binned into 20-60 min time intervals to study O2(1-del(sub g)) diurnal behavior. Derived abundances of O2(1-del(sub g)) between 50 and 70 km for the four observation dates are 9%, 31%, 3%, and 26%, respectively, each +/- 10% higher than predicted, based on the simple photochemistry of lower mesospheric O2(1-del(sub g)). Modeled variation of [O2(1-del(sub g))] with time of day agrees with observed variation in that the observed difference between model and data abundances is constant throughout the daylight hours of each observation date. Model underprediction Of [02(lAg)] is consistent with similar model underprediction of mesospheric [O3]. A perturbation to the photochemical model that forces decreased ozone chemical loss brings brings both model [O3] and [O2(1-del(sub g))] into agreement with the observations. O2(1-del(sub g)) abundances derived from these 1.2 mm observations agree with [O2(1-del(sub g))] values derived from comparable SME observations of the 1.27 micrometers emission, with assumption of a 3880 sec O2(1-del(sub g)) radiative lifetime. The 6800 sec O2(1-del(sub g)) radiative lifetime proposed by

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

NASA Astrophysics Data System (ADS)

Lipnicky, Andrew; Chakrabarti, Sukanya

2017-06-01

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

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.

Mesospheric ozone destruction by high-energy electron precipitation associated with pulsating aurora

NASA Astrophysics Data System (ADS)

Turunen, Esa; Kero, Antti; Verronen, Pekka T.; Miyoshi, Yoshizumi; Oyama, Shin-Ichiro; Saito, Shinji

2016-10-01

Energetic particle precipitation into the upper atmosphere creates excess amounts of odd nitrogen and odd hydrogen. These destroy mesospheric and upper stratospheric ozone in catalytic reaction chains, either in situ at the altitude of the energy deposition or indirectly due to transport to other altitudes and latitudes. Recent statistical analysis of satellite data on mesospheric ozone reveals that the variations during energetic electron precipitation from Earth's radiation belts can be tens of percent. Here we report model calculations of ozone destruction due to a single event of pulsating aurora early in the morning on 17 November 2012. The presence of high-energy component in the precipitating electron flux (>200 keV) was detected as ionization down to 68 km altitude, by the VHF incoherent scatter radar of European Incoherent Scatter (EISCAT) Scientific Association (EISCAT VHF) in Tromsø, Norway. Observations by the Van Allen Probes satellite B showed the occurrence of rising tone lower band chorus waves, which cause the precipitation. We model the effect of high-energy electron precipitation on ozone concentration using a detailed coupled ion and neutral chemistry model. Due to a 30 min, recorded electron precipitation event we find 14% odd oxygen depletion at 75 km altitude. The uncertainty of the higher-energy electron fluxes leads to different possible energy deposition estimates during the pulsating aurora event. We find depletion of odd oxygen by several tens of percent, depending on the precipitation characteristics used in modeling. The effect is notably maximized at the sunset time following the occurrence of the precipitation.

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.

Thermal zonal winds in the Venus mesosphere from the Venus Express temperature soundings

NASA Astrophysics Data System (ADS)

Piccialli, Arianna; Titov, Dmitri; Tellmann, Silvia; Migliorini, Alessandra; Read, Peter; Grassi, Davide; Paetzold, Martin; Haeusler, Bernd; Piccioni, Giuseppe; Drossart, Pierre

The Venus mesosphere (60-100 km altitude) is a transition region characterized by extremely complex dynamics: strong retrograde zonal winds dominate in the troposphere and lower meso-sphere while a solar-antisolar circulation can be observed in the upper mesosphere. The super-rotation extends from the surface up to the cloud top (˜65 km altitude) with wind speeds of only a few meters per second near the surface and reaching a maximum value of ˜100 m s-1 at cloud top, corresponding to a rotation period of ˜4 Earth days (˜60 times faster than Venus itself). The solar-antisolar circulation is driven by the day-night contrast in solar heating, and occurs above 110 km altitude with speeds of 120 m s-1 . The processes responsible for maintain-ing the zonal super-rotation in the lower atmosphere and its transition to the solar-antisolar circulation in the upper atmosphere are still poorly understood (Schubert et al.,2007). Different techniques have been used to obtain direct observations of wind at various altitudes: tracking of clouds in ultraviolet (UV) and near infrared (NIR) images give information on wind speeds at the cloud top (Moissl et al., 2009; Sanchez-Lavega et al., 2008) and within the clouds (˜47 km, ˜61 km) (Sanchez-Lavega et al., 2008) while ground-based measurements of Doppler shifts in the CO2 band at 10 µm (Sornig et al., 2008) and in several CO millimiter lines (Rengel et al., 2008) provide wind speeds above the clouds up to ˜110 km altitude. The deep atmosphere from the surface up to the cloud top has been investigated through the Doppler tracking of descent probes and balloons (Counselman et al., 1980; Kerzhanovich and Limaye, 1985). In the mesosphere, between 45-85 km of altitude, where direct observations of wind are not possible, the zonal wind field can be derived from the vertical temperature structure using a special approximation of the thermal wind equation: based on cyclostrophic balance. Previous studies (Leovy, 1973; Newman et al

Oblique propagation of monsoon gravity waves during the northern hemisphere 2007 summer

NASA Astrophysics Data System (ADS)

Thurairajah, Brentha; Siskind, David E.; Bailey, Scott M.; Carstens, Justin N.; Russell, James M.; Mlynczak, Martin G.

2017-05-01

We present a combination of satellite observation and high-resolution model output to understand monsoon convection as a source of high-latitude mesospheric gravity waves (GWs). The GWs generated over the Northern Hemisphere (NH) monsoon region during the 2007 summer and the role of the winds in focusing these GWs toward the high-latitude middle atmosphere are analyzed using the Sounding of the Atmosphere using Broadband Emission Radiometry/Thermosphere Ionosphere Mesosphere Energetics and Dynamics (SABER/TIMED) satellite temperature data and the high-resolution Navy Operational Global Atmospheric Prediction System-Advanced Level Physics High Altitude (NOGAPS/ALPHA) model results. In the NH, above the stratosphere, the monsoon GW Momentum Flux (GWMF) exhibits a poleward tilt that follows the slanted structure of the easterly jet. The correlation coefficients (>0.5) between the time series of NH tropical stratospheric GWMF and the global winds also have a slanted structure that coincide with the easterly jet, confirming the modeling theory that stratospheric monsoon GWs are refracted into the summer easterly jet and can reach the high-latitude mesosphere. Since Polar Mesospheric Clouds (PMCs) are sensitive indicators of changes in the polar summer mesosphere, we compared the time series of tropical stratospheric GWMF to the PMC occurrence frequency (OF) obtained from the Cloud Imaging and Particle Size/Aeronomy of Ice in the Mesosphere satellite data to assess the influence of this wave focusing in the mesosphere. There is a significant positive correlation between the high-latitude PMC OF and the tropical stratospheric GWMF suggesting a definite influence of monsoon GWs on the high-latitude mesosphere. The disagreement in correlation at the end of the PMC season is attributed to the enhancement of the quasi 5 day planetary wave dominating over the influence of monsoon GWs on PMCs.

Improving the twilight model for polar cap absorption nowcasts

NASA Astrophysics Data System (ADS)

Rogers, N. C.; Kero, A.; Honary, F.; Verronen, P. T.; Warrington, E. M.; Danskin, D. W.

2016-11-01

During solar proton events (SPE), energetic protons ionize the polar mesosphere causing HF radio wave attenuation, more strongly on the dayside where the effective recombination coefficient, αeff, is low. Polar cap absorption models predict the 30 MHz cosmic noise absorption, A, measured by riometers, based on real-time measurements of the integrated proton flux-energy spectrum, J. However, empirical models in common use cannot account for regional and day-to-day variations in the daytime and nighttime profiles of αeff(z) or the related sensitivity parameter, m=A>/&sqrt;J. Large prediction errors occur during twilight when m changes rapidly, and due to errors locating the rigidity cutoff latitude. Modeling the twilight change in m as a linear or Gauss error-function transition over a range of solar-zenith angles (χl < χ < χu) provides a better fit to measurements than selecting day or night αeff profiles based on the Earth-shadow height. Optimal model parameters were determined for several polar cap riometers for large SPEs in 1998-2005. The optimal χl parameter was found to be most variable, with smaller values (as low as 60°) postsunrise compared with presunset and with positive correlation between riometers over a wide area. Day and night values of m exhibited higher correlation for closely spaced riometers. A nowcast simulation is presented in which rigidity boundary latitude and twilight model parameters are optimized by assimilating age-weighted measurements from 25 riometers. The technique reduces model bias, and root-mean-square errors are reduced by up to 30% compared with a model employing no riometer data assimilation.

Mesospheric sodium structure variability on horizontal scales relevant to laser guide star asterisms

NASA Astrophysics Data System (ADS)

Pfrommer, Thomas; Hickson, Paul

2012-07-01

Adaptive optics (AO) systems of modern telescopes use laser guide stars, produced by resonant excitation of sodium atoms in the mesosphere at around 92 km. Wavefront sensor subapertures, if sufficiently far away from the primary mirror center, resolve the internal structure of the sodium layer. The variability of this structure is caused by the influence of gravity waves and wind shear turbulence. The relevance of such dynamics to AO has been investigated over the past four years. A high-resolution lidar system, employed at the 6-m liquid mirror telescope, which is located near Vancouver, Canada, has been used to study mesospheric dynamics, such as the temporal behavior of the mean altitude. The main results from this study have been published elsewhere and will be summarized here. Along with the temporal variability, the mean altitude on horizontal scales of order IOs of meters has been studied by introducing a tip/tilt stage in the experimental setup. This enables us to swap the laser pulse within a 1 arcmin field of view. The horizontal mean altitude structure function has been measured on 10 observing nights between July and August 2011. Results reveal severe structural differences and a strong horizontal anisotropy. Individual laser beacons in a laser guide star asterism will therefore have at the same time significantly different focus heights. By propagating this 2d structure function to the entrance pupil of a 39 m telescope, we derive a differential focus wavefront error map.

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.

Latitudinal Dependence of the Energy Input into the Mesosphere by High Energy Electrons

NASA Technical Reports Server (NTRS)

Wagner, C. U.; Nikutowski, B.; Ranta, H.

1984-01-01

Night-time ionspheric absorption measurements give the possibility to study the precipitation of high energy electrons into the mesosphere during and after magnetospheric storms. The uniform Finnish riometer network was used together with measurements from Kuhlungsborn and Collm (GDR) to investigate the night-time absorption as a function of latitude (L=6.5 to 2.5) and storm-time for seven storms. The common trends visible in all these events are summarized in a schematic average picture, showing the distribution of increased ionospheric absorption as a function of latitude (L value) and storm-time.

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.

Cytotoxicity and genotoxicity induced in vitro by solvent-extractable organic matter of size-segregated urban particulate matter.

PubMed

Velali, Ekaterini; Papachristou, Eleni; Pantazaki, Anastasia; Choli-Papadopoulou, Theodora; Argyrou, Nikoleta; Tsourouktsoglou, Theodora; Lialiaris, Stergios; Constantinidis, Alexandros; Lykidis, Dimitrios; Lialiaris, Thedore S; Besis, Athanasios; Voutsa, Dimitra; Samara, Constantini

2016-11-01

Three organic fractions of different polarity, including a non polar organic fraction (NPOF), a moderately polar organic fraction (MPOF), and a polar organic fraction (POF) were obtained from size-segregated (<0.49, 0.49-0.97, 0.97-3 and >3 μm) urban particulate matter (PM) samples, and tested for cytotoxicity and genotoxicity using a battery of in vitro assays. The cytotoxicity induced by the organic PM fractions was measured by the mitochondrial dehydrogenase (MTT) cell viability assay applied on MRC-5 human lung epithelial cells. DNA damages were evaluated through the comet assay, determination of the poly(ADP-Ribose) polymerase (PARP) activity, and the oxidative DNA adduct 8-hydroxy-deoxyguanosine (8-OHdG) formation, while pro-inflammatory effects were assessed by determination of the tumor necrosis factor-alpha (TNF-α) mediator release. In addition, the Sister Chromatid Exchange (SCE) inducibility of the solvent-extractable organic matter was measured on human peripheral lymphocyte. Variations of responses were assessed in relation to the polarity (hence the expected composition) of the organic PM fractions, particle size, locality, and season. Organic PM fractions were found to induce rather comparable Cytotoxicity and genotoxicity of PM appeared to be rather independent from the polarity of the extractable organic PM matter (EOM) with POF often being relatively more toxic than NPOF or MPOF. All assays indicated stronger mass-normalized bioactivity for fine than coarse particles peaking in the 0.97-3 and/or the 0.49-0.97 μm size ranges. Nevertheless, the air volume-normalized bioactivity in all assays was highest for the <0.49 μm size range highlighting the important human health risk posed by the inhalation of these quasi-ultrafine particles. Copyright © 2016 Elsevier Ltd. All rights reserved.

Earth Observation

NASA Image and Video Library

2011-08-02

ISS028-E-020276 (2 Aug. 2011) --- This photograph of polar mesospheric clouds was acquired at an altitude of just over 202 nautical miles (about 322 kilometers) in the evening hours (03:19:54 Greenwich Mean Time) on Aug. 2, 2011, as the International Space Station was passing over the English Channel. The nadir coordinates of the station were 49.1 degrees north latitude and 5.5 degrees west longitude. Polar mesospheric clouds (also known as noctilucent, or ?night-shining? clouds) are transient, upper atmospheric phenomena that are usually observed in the summer months at high latitudes (greater than 50 degrees) of both the Northern and Southern Hemispheres. They appear bright and cloudlike while in deep twilight. They are illuminated by sunlight when the lower layers of the atmosphere are in the darkness of Earth?s shadow. The horizon of Earth appears at the bottom of the image, with some layers of the lower atmosphere already illuminated by the rising sun. The higher, bluish-colored clouds look much like wispy cirrus clouds, which can be found as high as 60,000 feet (18 kilometers) in the atmosphere. However noctilucent clouds, as seen here, are observed in the mesosphere at altitudes of 250,000 to 280,000 feet (about 76 to 85 kilometers). Astronaut observations of polar mesospheric clouds over northern Europe in the summer are not uncommon.

Observations of mesospheric turbulence by rocket probe and VHF radar, part 2.4A

NASA Astrophysics Data System (ADS)

Royrvik, O.; Smith, L. G.

1984-12-01

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.

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.

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

Gravity Waves and Mesospheric Clouds in the Summer Middle Atmosphere: A Comparison of Lidar Measurements and Ray Modeling of Gravity Waves Over Sondrestrom, Greenland

NASA Technical Reports Server (NTRS)

Gerrard, Andrew J.; Kane, Timothy J.; Eckermann, Stephen D.; Thayer, Jeffrey P.

2004-01-01

We conducted gravity wave ray-tracing experiments within an atmospheric region centered near the ARCLITE lidar system at Sondrestrom, Greenland (67N, 310 deg E), in efforts to understand lidar observations of both upper stratospheric gravity wave activity and mesospheric clouds during August 1996 and the summer of 2001. The ray model was used to trace gravity waves through realistic three-dimensional daily-varying background atmospheres in the region, based on forecasts and analyses in the troposphere and stratosphere and climatologies higher up. Reverse ray tracing based on upper stratospheric lidar observations at Sondrestrom was also used to try to objectively identify wave source regions in the troposphere. A source spectrum specified by reverse ray tracing experiments in early August 1996 (when atmospheric flow patterns produced enhanced transmission of waves into the upper stratosphere) yielded model results throughout the remainder of August 1996 that agreed best with the lidar observations. The model also simulated increased vertical group propagation of waves between 40 km and 80 km due to intensifying mean easterlies, which allowed many of the gravity waves observed at 40 km over Sondrestrom to propagate quasi-vertically from 40-80 km and then interact with any mesospheric clouds at 80 km near Sondrestrom, supporting earlier experimentally-inferred correlations between upper stratospheric gravity wave activity and mesospheric cloud backscatter from Sondrestrom lidar observations. A pilot experiment of real-time runs with the model in 2001 using weather forecast data as a low-level background produced less agreement with lidar observations. We believe this is due to limitations in our specified tropospheric source spectrum, the use of climatological winds and temperatures in the upper stratosphere and mesosphere, and missing lidar data from important time periods.

Spatio-temporal dynamics of an active, polar, viscoelastic ring.

PubMed

Marcq, Philippe

2014-04-01

Constitutive equations for a one-dimensional, active, polar, viscoelastic liquid are derived by treating the strain field as a slow hydrodynamic variable. Taking into account the couplings between strain and polarity allowed by symmetry, the hydrodynamics of an active, polar, viscoelastic body include an evolution equation for the polarity field that generalizes the damped Kuramoto-Sivashinsky equation. Beyond thresholds of the active coupling coefficients between the polarity and the stress or the strain rate, bifurcations of the homogeneous state lead first to stationary waves, then to propagating waves of the strain, stress and polarity fields. I argue that these results are relevant to living matter, and may explain rotating actomyosin rings in cells and mechanical waves in epithelial cell monolayers.

Statistical analysis of mesospheric gravity waves over King Sejong Station, Antarctica (62.2°S, 58.8°W)

NASA Astrophysics Data System (ADS)

Kam, Hosik; Jee, Geonhwa; Kim, Yong; Ham, Young-bae; Song, In-Sun

2017-03-01

We have investigated the characteristics of mesospheric short period (<1 h) gravity waves which were observed with all-sky images of OH Meinel band and OI 557 nm airglows over King Sejong Station (KSS) (62.22°S, 58.78°W) during a period of 2008-2015. By applying 2-dimensional FFT to time differenced images, we derived horizontal wavelengths, phase speeds, and propagating directions (188 and 173 quasi-monochromatic waves from OH and OI airglow images, respectively). The majority of the observed waves propagated predominantly westward, implying that eastward waves were filtered out by strong eastward stratospheric winds. In order to obtain the intrinsic properties of the observed waves, we utilized winds simultaneously measured by KSS Meteor Radar and temperatures from Aura Microwave Limb Sounder (MLS). More than half the waves propagated horizontally, as waves were in Doppler duct or evanescent in the vertical direction. This might be due to strong eastward background wind field in the mesosphere over KSS. For freely propagating waves, the vertical wavelengths were in the interquartile range of 9-33 km with a median value of 15 km. The vertical wavelengths are shorter than those observed at Halley station (76°S, 27°W) where the majority of the observed waves were freely propagating. The difference in the wave propagating characteristics between KSS and Halley station suggests that gravity waves may affect mesospheric dynamics in this part of the Antarctic Peninsula more strongly than over the Antarctic continent. Furthermore, strong wind shear over KSS played an important role in changing the vertical wavenumbers as the waves propagated upward between two airglow layers (87 and 96 km).

Mesospheric Na Variability and Dependence on Geomagnetic and Solar Activity over Arecibo

NASA Astrophysics Data System (ADS)

Jain, K.; Raizada, S.; Brum, C. G. M.

2017-12-01

The Sodium (Na) resonance lidars located at the Arecibo Observatory offer an excellent opportunity to study the mesosphere/lower thermosphere(MLT) region. Different metals like Fe, Mg, Na, K, Ca and their ions are deposited in the 80 - 120 km altitude range due to the ablation of meteors caused by frictional heating during their entry into the Earth's atmosphere. We present an investigation of the neutral mesospheric Na atom layers over Arecibo. Data on the Na concentrations was collected using a resonance lidar tuned to the of Na wavelength at 589 nm. This wavelength is achieved with a dye-laser pumped by the second harmonic (532 nm) generated from a state-of-the-art commercial Nd:YAG laser. The backscattered signal is received on a 0.8 m (diameter) Cassegrain telescope. The study is based on this data acquired from 1998-2017 and its relation to variations in geomagnetic and solar conditions. We also investigate seasonal and long term trends in the data. The nightly-averaged altitude profiles were modeled as Gaussian curves. From this modeled data we obtain parameters such as the peak, abundance, centroid and width of the main Na layer. Preliminary results show that the Na abundance is more sensitive to changes in geomagnetic and solar variations as compared to the width and centroid height. The seasonal variation exhibits higher peak densities during the local summer and has a secondary maximum during the winter [as shown in the attached figure]. Our analysis demonstrates a decrease in the peak and the abundance of Na atoms with the increase of solar and geomagnetic activity.

Annual and Semi-Annual Temperature Oscillations in the Upper Mesosphere

NASA Technical Reports Server (NTRS)

Niciejewski, R. J.; Killeen, T. L.

1995-01-01

Fourier transform spectrometer observations of the mesosphere have been performed at the University of Michigan (latitude: 42.5 N) on a long term basis. A database of near infrared Meinel hydroxyl spectra has been accumulated from which rotational temperatures have been determined. Harmonic analysis of one-day averaged temperatures for the period 1992.0 to 1994.5 has shown a distinct annual and semi-annual variation. Subsequent fitting of a five term periodic function characterizing the annual and semi-annual temperature oscillations to the daily averaged temperatures was performed. The resultant mean temperature and the amplitudes and phases of the annual and semi-annual variations are shown to coincide with an emission height slightly above 85 km which is consistent with the mean rocket derived altitude for peak nocturnal hydroxyl emission.

Arctic Strato-Mesospheric Temperature and Wind Variations

NASA Technical Reports Server (NTRS)

Schmidlin, F. J.; Goldberg, R. A.

2004-01-01

Upper stratosphere and mesosphere rocket measurements are actively used to investigate interaction between the neutral, electrical, and chemical atmospheres and between lower and upper layers of these regions. Satellite temperature measurements from HALOE and from inflatable falling spheres complement each other and allow illustrations of the annual cycle to 85 km altitude. Falling sphere wind and temperature measurements reveal variability that differs as a function of altitude, location, and time. We discuss the state of the Arctic atmosphere during the summer 2002 (Andoya, Norway) and winter 2003 (ESRANGE, Sweden) campaigns of MaCWAVE. Balloon-borne profiles to 30 km altitude and sphere profiles between 50 and 90 km show unique small-scale structure. Nonetheless, there are practical implications that additional measurements are very much needed to complete the full vertical profile picture. Our discussion concentrates on the distribution of temperature and wind and their variability. However, reliable measurements from other high latitude NASA programs over a number of years are available to help properly calculate mean values and the distribution of the individual measurements. Since the available rocket data in the Arctic's upper atmosphere are sparse the results we present are basically a snapshot of atmospheric structure.

A two-dimensional model of odd nitrogen in the thermosphere and mesosphere

NASA Technical Reports Server (NTRS)

Gerard, J. C.; Roble, R. G.; Rusch, D. W.

1980-01-01

Satellite measurements of the global nitric oxide distribution demonstrating the need for a two dimensional model of odd nitrogen photochemistry and transport in the thermosphere and mesosphere are reviewed. The main characteristics of a new code solving the transport equation for N(4S), N(2D), and N0 are given. This model extends from pole to pole between 75 and 275 km and reacts to the magnetic activity, the ultraviolet solar flux, and the neutral wind field. The effects of ionization and subsequent odd nitrogen production by high latitude particle precipitation are also included. Preliminary results are illustrated for a magnetically quiet solar minimum period with no neutral wind.

The Aeronomy of Ice in the Mesosphere Mission: Overview and Early Results

NASA Astrophysics Data System (ADS)

Russell, J. M.; Bailey, S. M.; Thomas, G.; Rusch, D.; Gordley, L. L.; Hervig, M.; Horanyi, M.; Randall, C.; McClintock, W.; Siskind, D. E.; Stevens, M.; Englert, C.; Taylor, M.; Summeers, M.; Merkel, A.

2007-12-01

The Aeronomy of Ice in the Mesosphere (AIM) mission was launched from Vandenberg Air Force Base in California at 1:26:03 PDT on April 25, 2007 becoming the first satellite mission dedicated to the study of noctilucent clouds. A Pegasus XL rocket launched the satellite into a near perfect 600 km sun synchronous circular orbit. AIM carries three instruments - a nadir imager, a solar occultation instrument and in-situ cosmic dust detectors - that were specifically selected because of their ability to provide key measurements needed to address the six AIM science objectives. Brief descriptions of the science, instruments and observation scenario will be presented along with early science results.

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.

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.

Comparison of Mesospheric Winds From a High-Altitude Meteorological Analysis System and Meteor Radar Observations During the Boreal Winters of 2009-2010 and 2012-2013

NASA Technical Reports Server (NTRS)

McCormack, J.; Hoppel, K.; Kuhl, D.; de Wit, R.; Stober, G.; Espy, P.; Baker, N.; Brown, P.; Fritts, D.; Jacobi, C.;

Sensitivity of Middle Atmospheric Temperature and Circulation in the UIUC Mesosphere-Stratosphere-Troposphere GCM to the Treatment of Subgrid-Scale Gravity-Wave Breaking

NASA Technical Reports Server (NTRS)

Yang, Fanglin; Schlesinger, Michael E.; Andranova, Natasha; Zubov, Vladimir A.; Rozanov, Eugene V.; Callis, Lin B.

2003-01-01

The sensitivity of the middle atmospheric temperature and circulation to the treatment of mean- flow forcing due to breaking gravity waves was investigated using the University of Illinois at Urbana-Champaign 40-layer Mesosphere-Stratosphere-Troposphere General Circulation Model (MST-GCM). Three GCM experiments were performed. The gravity-wave forcing was represented first by Rayleigh friction, and then by the Alexander and Dunkerton (AD) parameterization with weak and strong breaking effects of gravity waves. In all experiments, the Palmer et al. parameterization was included to treat the breaking of topographic gravity waves in the troposphere and lower stratosphere. Overall, the experiment with the strong breaking effect simulates best the middle atmospheric temperature and circulation. With Rayleigh friction and the weak breaking effect, a large warm bias of up to 60 C was found in the summer upper mesosphere and lower thermosphere. This warm bias was linked to the inability of the GCM to simulate the reversal of the zonal winds from easterly to westerly crossing the mesopause in the summer hemisphere. With the strong breaking effect, the GCM was able to simulate this reversal, and essentially eliminated the warm bias. This improvement was the result of a much stronger meridional transport circulation that possesses a strong vertical ascending branch in the summer upper mesosphere, and hence large adiabatic cooling. Budget analysis indicates that 'in the middle atmosphere the forces that act to maintain a steady zonal-mean zonal wind are primarily those associated with the meridional transport circulation and breaking gravity waves. Contributions from the interaction of the model-resolved eddies with the mean flow are small. To obtain a transport circulation in the mesosphere of the UIUC MST-GCM that is strong enough to produce the observed cold summer mesopause, gravity-wave forcing larger than 100 m/s/day in magnitude is required near the summer mesopause. In

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.;

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.

Equatorial Mesosphere and Lower Thermosphere/Ionosphere (MLTI) Response to Severe Cyclonic Storm `Aila' and `Ward' observed over North Indian Ocean

NASA Astrophysics Data System (ADS)

G J, B.

2016-12-01

The present work investigates the Equatorial Mesosphere Lower Thermosphere/Ionosphere (MLTI) response to severe cyclonic storm `Aila (23-26 May 2009)' and `Ward (10-16 December 2009)' which were observed over north Indian Ocean during the extended solar minimum of the year 2009. This report reveals the coupling between Tropical Cyclone and MLTI region. Tropical cyclone track and data can be obtained from Indian Meteorological Department (IMD), New Delhi. Mesospheric and Ionospheric variation can be examined with the help of ground based Mesosphere Lower Thermosphere (MLT) radar and Digisonde located at equatorial low latitude station, Tirunelveli (8.7oN, 77.8oE). The Outgoing Long wave Radiation (OLR) data is used as a proxy for identifying the convective activity, which are retrieved from NOAA Climate Data Centre. It is observed that the tropical cyclone induced convection as the driving agent for the increased gravity wave activity in the lower atmosphere. These upward propagating gravity waves deposit their energy and momentum into the upper region of atmosphere as `Travelling Ionospheric Disturbances (TIDs). During the cyclonic storm periods, we found increased gravity wave amplitude with upward propagation in the MLT region. Ionospheric response to severe cyclonic storm is examined with the dynamical parameters, foF2, hmF2, h'F2 and Total Election Content (TEC). Significant increase of foF2 frequency is observed during `Ward' cyclonic storm. Drastic variation in foF2 and h'F2 is observed during Aila cyclonic storm than ward event. More statistical analysis has been done for finding the correlation between cyclonic storm and Ionospheric parameters. Detailed results will be presented in the meeting.

Radiative-photochemical response of the mesosphere to dynamical forcing

NASA Technical Reports Server (NTRS)

Frederick, J. E.

1981-01-01

Combination of the chemical continuity equation for odd oxygen with the second law of thermodynamics yields analytic solutions which describe the coupled behavior of temperature and ozone perturbations in response to an externally specified forcing. The results appear in a form which allows easy physical interpretation of the coupling between radiative and photochemical processes. When the forcing is chosen to mimic a planetary scale wave, the theory shows that photochemical acceleration of radiative damping reduces the amplitude of the temperature perturbation by an amount which increases with the wave period. Although ozone fluctuations are anti-correlated with those in temperature, minima in ozone do not coincide exactly in longitude with temperature maxima. The percentage variation in ozone increases upward and is always larger than that in temperature at the same pressure. This demonstrates that variations in ozone on constant pressure surfaces may serve as a sensitive indicator of wave activity in the mesosphere.

Relationship between dissolved organic matter quality and microbial community composition across polar glacial environments.

PubMed

Smith, H J; Dieser, M; McKnight, D M; SanClements, M D; Foreman, C M

2018-05-14

Vast expanses of Earth's surface are covered by ice, with microorganisms in these systems affecting local and global biogeochemical cycles. We examined microbial assemblages from habitats fed by glacial meltwater within the McMurdo Dry Valleys, Antarctica, and on the west Greenland Ice Sheet, (GrIS) evaluating potential physicochemical factors explaining trends in community structure. Microbial assemblages present in the different Antarctic dry valley habitats were dominated by Sphingobacteria and Flavobacteria, while Gammaproteobacteria and Sphingobacteria prevailed in west GrIS supraglacial environments. Microbial assemblages clustered by location (Canada Glacier, Cotton Glacier, west GrIS) and were separated by habitat type (i.e. ice, cryoconite holes, supraglacial lakes, sediment, and stream water). Community dissimilarities were strongly correlated with dissolved organic matter (DOM) quality. Microbial meltwater assemblages were most closely associated with different protein-like components of the DOM pool. Microbes in environments with mineral particles (i.e. stream sediments, cryoconite holes) were linked to DOM containing more humic-like fluorescence. Our results demonstrate the establishment of distinct microbial communities within ephemeral glacial meltwater habitats, with DOM-microbe interactions playing an integral role in shaping communities on local and polar spatial scales.

Polarized Light Microscopy

NASA Technical Reports Server (NTRS)

Frandsen, Athela F.

2016-01-01

Polarized light microscopy (PLM) is a technique which employs the use of polarizing filters to obtain substantial optical property information about the material which is being observed. This information can be combined with other microscopy techniques to confirm or elucidate the identity of an unknown material, determine whether a particular contaminant is present (as with asbestos analysis), or to provide important information that can be used to refine a manufacturing or chemical process. PLM was the major microscopy technique in use for identification of materials for nearly a century since its introduction in 1834 by William Fox Talbot, as other techniques such as SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared spectroscopy), XPD (X-ray Powder Diffraction), and TEM (Transmission Electron Microscopy) had not yet been developed. Today, it is still the only technique approved by the Environmental Protection Agency (EPA) for asbestos analysis, and is often the technique first applied for identification of unknown materials. PLM uses different configurations in order to determine different material properties. With each configuration additional clues can be gathered, leading to a conclusion of material identity. With no polarizing filter, the microscope can be used just as a stereo optical microscope, and view qualities such as morphology, size, and number of phases. With a single polarizing filter (single polars), additional properties can be established, such as pleochroism, individual refractive indices, and dispersion staining. With two polarizing filters (crossed polars), even more can be deduced: isotropy vs. anisotropy, extinction angle, birefringence/degree of birefringence, sign of elongation, and anomalous polarization colors, among others. With the use of PLM many of these properties can be determined in a matter of seconds, even for those who are not highly trained. McCrone, a leader in the field of polarized light microscopy, often

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.

Evolution of the Antarctic polar vortex in spring: Response of a GCM to a prescribed Antarctic ozone hole

NASA Technical Reports Server (NTRS)

Boville, B. A.; Kiehl, J. T.; Briegleb, B. P.

1988-01-01

The possible effect of the Antartic ozone hole on the evolution of the polar vortex during late winter and spring using a general circulation model (GCM) is examined. The GCM is a version of the NCAR Community Climate Model whose domain extends from the surface to the mesosphere and is similar to that described on Boville and Randel (1986). Ozone is not a predicted variable in the model. A zonally averaged ozone distribution is specified as a function of latitude, pressure and month for the radiation parameterization. Rather that explicitly address reasons for the formation of the ozone hole, researchers postulate its existence and ask what effect it has on the subsequent evolution of the vortex. The evolution of the model when an ozone hole is imposed is then discussed.

Lambda polarization feasibility study at BM@N

NASA Astrophysics Data System (ADS)

Suvarieva, Dilyna; Gudima, Konstantin; Zinchenko, Alexander

2017-03-01

Heavy strange objects (hyperons) could provide essential signatures of the excited and compressed baryonic matter. At NICA, it is planned to study hyperons both in the collider mode (MPD detector) and the fixed-target one (BM@N setup). Measurements of strange hyperons polarization could give additional information on the strong interaction mechanisms. In heavy-ion collisions, such measurements are even more valuable since the polarization is expected to be sensitive to characteristics of the QCD medium (vorticity, hydrodynamic helicity) and to QCD anomalous transport. In this analysis, the possibility to measure at BM@N the polarization of the lightest strange hyperon Λ is studied in Monte Carlo event samples produced with the DCM-QGSM generator. It is shown that the detector will allow to measure Λ polarization with a precision required to check the model predictions.

Videographic Education: Owning the Polar Crisis

NASA Astrophysics Data System (ADS)

Vachon, R. W.; Buhr, S. M.

2007-12-01

Television and internet-served video is an increasingly important media tool for reaching into society. This talk will present clips from a film designed to educate the public about warming in the polar regions, the socioeconomic and environmental implications of this warming; and the actions we can take to slow down human contributions to climate change. This talk will present a short film Owning the Polar Crisis, which is drawn from footage for Polar Visions, a four segment film available for educational audiences and the public.. The films are unique in that they draw from the perspectives of well-known climate scientists, citizens from all over the planet and natives of the Arctic. The compelling images were taken from numerous locations around the Arctic, including Alaska and Greenland. Owning the Polar Crisis was filmed, directed and produced by Dr. Ryan Vachon, a climate scientist and videographer with an intimate knowledge of the subject matter.

Technical note: Evaluation of the simultaneous measurements of mesospheric OH, HO2, and O3 under a photochemical equilibrium assumption - a statistical approach

NASA Astrophysics Data System (ADS)

Kulikov, Mikhail Y.; Nechaev, Anton A.; Belikovich, Mikhail V.; Ermakova, Tatiana S.; Feigin, Alexander M.

2018-05-01

This Technical Note presents a statistical approach to evaluating simultaneous measurements of several atmospheric components under the assumption of photochemical equilibrium. We consider simultaneous measurements of OH, HO2, and O3 at the altitudes of the mesosphere as a specific example and their daytime photochemical equilibrium as an evaluating relationship. A simplified algebraic equation relating local concentrations of these components in the 50-100 km altitude range has been derived. The parameters of the equation are temperature, neutral density, local zenith angle, and the rates of eight reactions. We have performed a one-year simulation of the mesosphere and lower thermosphere using a 3-D chemical-transport model. The simulation shows that the discrepancy between the calculated evolution of the components and the equilibrium value given by the equation does not exceed 3-4 % in the full range of altitudes independent of season or latitude. We have developed a statistical Bayesian evaluation technique for simultaneous measurements of OH, HO2, and O3 based on the equilibrium equation taking into account the measurement error. The first results of the application of the technique to MLS/Aura data (Microwave Limb Sounder) are presented in this Technical Note. It has been found that the satellite data of the HO2 distribution regularly demonstrate lower altitudes of this component's mesospheric maximum. This has also been confirmed by model HO2 distributions and comparison with offline retrieval of HO2 from the daily zonal means MLS radiance.

On the composite response of the MLT to major sudden stratospheric warming events with elevated stratopause

NASA Astrophysics Data System (ADS)

Limpasuvan, Varavut; Orsolini, Yvan J.; Chandran, Amal; Garcia, Rolando R.; Smith, Anne K.

2016-05-01

Based on a climate-chemistry model (constrained by reanalyses below ~50 km), the zonal-mean composite response of the mesosphere and lower thermosphere (MLT) to major sudden stratospheric warming events with elevated stratopauses demonstrates the role of planetary waves (PWs) in driving the mean circulation in the presence of gravity waves (GWs), helping the polar vortex recover and communicating the sudden stratospheric warming (SSW) impact across the equator. With the SSW onset, strong westward PW drag appears above 80 km primarily from the dissipation of wave number 1 perturbations with westward period of 5-12 days, generated from below by the unstable westward polar stratospheric jet that develops as a result of the SSW. The filtering effect of this jet also allows eastward propagating GWs to saturate in the winter MLT, providing eastward drag that promotes winter polar mesospheric cooling. The dominant PW forcing translates to a net westward drag above the eastward mesospheric jet, which initiates downwelling over the winter pole. As the eastward polar stratospheric jet returns, this westward PW drag persists above 80 km and acts synergistically with the return of westward GW drag to drive a stronger polar downwelling that warms the pole adiabatically and helps reform the stratopause at an elevated altitude. With the polar wind reversal during the SSW onset, the westward drag by the quasi-stationary PW in the winter stratosphere drives an anomalous equatorial upwelling and cooling that enhance tropical stratospheric ozone. Along with equatorial wind anomalies, this ozone enhancement subsequently amplifies the migrating semidiurnal tide amplitude in the winter midlatitudes.

Waves in the Mesosphere of Venus as seen by the Venus Express Radio Science Experiment VeRa

NASA Astrophysics Data System (ADS)

Tellmann, Silvia; Häusler, B.; Hinson, D. P.; Tyler, G.; Andert, T. P.; Bird, M. K.; Imamura, T.; Pätzold, M.; Remus, S.

2013-10-01

The Venus Express Radio Science Experiment (VeRa) has retrieved more than 700 profiles of the mesosphere and troposphere of Venus. These profiles cover a wide range of latitudes and local times, enabling study of atmospheric wave phenomena over a range spatial scales at altitudes of 40-90 km. In addition to quasi-horizontal waves and eddies on near planetary scales, diurnally forced eddies and thermal tides, small-scale gravity waves, and turbulence play a significant role in the development and maintenance of atmospheric super-rotation. Small-scale temperature variations with vertical wavelengths of 4 km or less have wave amplitudes reaching TBD km in the stable atmosphere above the tropopause, in contrast with much weaker temperature perturbations observed in the middle cloud layer below. The strength of gravity waves increases with latitude in both hemispheres. The results suggest that convection at low latitudes and topographical forcing at high northern latitudes—possibly in combination with convection and/or Kelvin-Helmholtz instabilities—play key roles in the genesis of gravity waves. Further, thermal tides also play an important role in the mesosphere. Diurnal and semi-diurnal wave modes are observed at different latitudes and altitudes. The latitudinal and height dependence of the thermal tide modes will be investigated.

Kinetic Requirements for the Measurement of Mesospheric Water Vapor at 6.8 (microns) under Non-LTE Conditions

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Mlynczak, Martin G.; Lopez-Puertas, Manuel; Russell, James M., III

1999-01-01

We present accuracy requirements for specific kinetic parameters used to calculate the populations and vibrational temperatures of the H2O(010) and H2O(020) states in the terrestrial mesosphere. The requirements are based on rigorous simulations of the retrieval of mesospheric water vapor profiles from measurements of water vapor infrared emission made by limb scanning instruments on orbiting satellites. Major improvements in the rate constants that describe vibration-to- vibration exchange between the H2O(010) and 02(1) states are required in addition to improved specification of the rate of quenching Of O2(1) by atomic oxygen (0). It is also necessary to more accurately determine the yield of vibrationally excited O2(l) resulting from ozone photolysis. A contemporary measurement of the rate of quenching of H2O(010) by N2 and O2 is also desirable. These rates are either highly uncertain or have never before been measured at atmospheric temperatures. The suggested improvements are necessary for the interpretation of water vapor emission measurements at 6.8 microns to be made from a new spaceflight experiment in less than 2 years. The approach to retrieving water vapor under non-LTE conditions is also presented.

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.

Electric and magnetic target polarization in quantum radar

NASA Astrophysics Data System (ADS)

Brandsema, Matthew J.; Narayanan, Ram M.; Lanzagorta, Marco

2017-05-01

In this paper, we discuss the effect that photon polarization has on the quantum radar cross section (QRCS) during the special case scenario of when the target is enveloped in either a uniform electric field or magnetic field and all of its atomic electric/magnetic dipole moments become aligned (target polarization). This target polarization causes the coupling between the photon and the matter to change and alter the scattering characteristics of the target. Most notably, it causes scattering to be very near zero at a specified angle. We also investigate the relationship between electric and magnetic types of coupling and find that the electric contribution dominates the QRCS response.

Rayleigh lidar observation of tropical mesospheric inversion layer: a comparison between dynamics and chemistry

NASA Astrophysics Data System (ADS)

Ramesh, K.; Sridharan, S.; Raghunath, K.

2018-04-01

The Rayleigh lidar at National Atmospheric Research Laboratory, Gadanki (13.5°N, 79.2°E), India operates at 532 nm green laser with 600 mJ/pulse since 2007. The vertical temperature profiles are derived above 30 km by assuming the atmosphere is in hydrostatic equilibrium and obeys ideal gas law. A large mesospheric inversion layer (MIL) is observed at 77.4-84.6 km on the night of 22 March 2007 over Gadanki. Although dynamics and chemistry play vital role, both the mechanisms are compared for the occurrence of the MIL in the present study.

Pulsar polarization measurements and the nonsymmetric gravitational theory

NASA Technical Reports Server (NTRS)

Krisher, Timothy P.

1991-01-01

Because of the breakdown of the Einstein equivalence principle in the nonsymmetric gravitational theory (NGT) of Moffat, orthogonally polarized electromagnetic waves can propagate at different velocities in a gravitational field. Moffat has proposed that galactic dark matter, in the form of cosmions, may act as a significant source of gravity in the NGT. We discuss how observations of the highly polarized radiation from distant pulsars could provide significant limits on the strength of the coupling of cosmions in the NGT.

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.

The effect of breaking gravity waves on the dynamics and chemistry of the mesosphere and lower thermosphere (invited review)

NASA Technical Reports Server (NTRS)

Garcia, R. R.

1986-01-01

The influence of breaking gravity waves on the dynamics and chemical composition of the 60 to 110 km region is investigated with a two dimensional model that includes a parameterization of gravity wave momentum deposition and diffusion. The dynamical model is described by Garcia and Solomon (1983) and Solomon and Garcia (1983) and includes a complete chemical scheme for the mesosphere and lower thermosphere. The parameterization of Lindzen (1981) is used to calculate the momentum deposited and the turbulent diffusion produced by the gravity waves. It is found that wave momentum deposition drives a very vigorous mean meridional circulation, produces a very cold summer mesopause and reverse the zonal wind jets above about 85 km. The seasonal variation of the turbulent diffusion coefficient is consistent with the behavior of mesospheric turbulences inferred from MST radar echoes. The large degree of consistency between model results and various types of dynamical and chemical data supports very strongly the hypothesis that breaking gravity waves play a major role in determining the zonally-averaged dynamical and chemical structure of the 60 to 110 km region of the atmosphere.

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

Response of mesospheric ozone to the heating of the lower ionosphere by high-power HF radio emission

NASA Astrophysics Data System (ADS)

Kulilov, Yu. Yu.; Frolov, V. L.; Grigor'ev, G. I.; Demkin, V. M.; Komrakov, G. P.; Krasilnokov, A. A.; Ryskin, V. G.

2013-01-01

We detected a decrease in the intensity of microwave radiation at the atmospheric ozone line at a frequency of 110836.04 MHz during ionospheric modification by high-power HF radiowaves radiated by the Sura Ionospheric Heating Facility. The obtained experimental data allowed us to hypothesize that this effect was caused by the fact that mesospheric ozone was affected by internal gravity waves generated in the E region of the ionosphere during its high-power HF radiowave heating.

Mesospheric sodium over Gadanki during Geminid meteor shower 2007

NASA Astrophysics Data System (ADS)

Lokanadham, B.; Rakesh Chandra, N.; Bhaskara Rao, S. Vijaya; Raghunath, K.; Yellaiah, G.

Resonance LIDAR system at Gadanki has been used for observing the mesospheric sodium during the night of 12-13 Dec 2007 when the peak activity of Geminid meteor shower occurred. Geminid meteor shower is observed along with the co-located MST radar in the altitude range 80-110 km. Sodium density profiles have been obtained with a vertical resolution of 300 m and a temporal resolution of 120 s with sodium resonance scattering LIDAR system. The sodium layers were found to exist in the altitude range 90-100 km. The enhanced Geminid meteor rates were recorded with the co-located MST radar in the same altitude range. The sodium concentration in the atmospheric altitude of ~93 km is estimated to be 2000 per cc where the meteoric concentration of Geminid is maximum and reduced to around 800 on the non activity of Geminid. These observations showed that the sodium levels in the E-region are found to be increasing during meteor shower nights at least by a factor of two.

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.

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.

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.

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.

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.

Antarctic Polar Descent and Planetary Wave Activity Observed in ISAMS CO from April to July 1992

NASA Technical Reports Server (NTRS)

Allen, D. R.; Stanford, J. L.; Nakamura, N.; Lopez-Valverde, M. A.; Lopez-Puertas, M.; Taylor, F. W.; Remedios, J. J.

2000-01-01

Antarctic polar descent and planetary wave activity in the upper stratosphere and lower mesosphere are observed in ISAMS CO data from April to July 1992. CO-derived mean April-to-May upper stratosphere descent rates of 15 K/day (0.25 km/day) at 60 S and 20 K/day (0.33 km/day) at 80 S are compared with descent rates from diabatic trajectory analyses. At 60 S there is excellent agreement, while at 80 S the trajectory-derived descent is significantly larger in early April. Zonal wavenumber 1 enhancement of CO is observed on 9 and 28 May, coincident with enhanced wave 1 in UKMO geopotential height. The 9 May event extends from 40 to 70 km and shows westward phase tilt with height, while the 28 May event extends from 40 to 50 km and shows virtually no phase tilt with height.

Central powering of the largest Lyman-α nebula is revealed by polarized radiation.

PubMed

Hayes, Matthew; Scarlata, Claudia; Siana, Brian

2011-08-17

High-redshift Lyman-α (Lyα) blobs are extended, luminous but rare structures that seem to be associated with the highest peaks in the matter density of the Universe. Their energy output and morphology are similar to those of powerful radio galaxies, but the source of the luminosity is unclear. Some blobs are associated with ultraviolet or infrared bright galaxies, suggesting an extreme starburst event or accretion onto a central black hole. Another possibility is gas that is shock-excited by supernovae. But not all blobs are associated with galaxies, and these ones may instead be heated by gas falling into a dark-matter halo. The polarization of the Lyα emission can in principle distinguish between these options, but a previous attempt to detect this signature returned a null detection. Here we report observations of polarized Lyα from the blob LAB1 (ref. 2). Although the central region shows no measurable polarization, the polarized fraction (P) increases to ∼20 per cent at a radius of 45 kiloparsecs, forming an almost complete polarized ring. The detection of polarized radiation is inconsistent with the in situ production of Lyα photons, and we conclude that they must have been produced in the galaxies hosted within the nebula, and re-scattered by neutral hydrogen.

Mesospheric front observations by the OH airglow imager carried out at Ferraz Station on King George Island, Antarctic Peninsula, in 2011

NASA Astrophysics Data System (ADS)

Giongo, Gabriel Augusto; Valentin Bageston, José; Prado Batista, Paulo; Wrasse, Cristiano Max; Dornelles Bittencourt, Gabriela; Paulino, Igo; Paes Leme, Neusa Maria; Fritts, David C.; Janches, Diego; Hocking, Wayne; Schuch, Nelson Jorge

2018-02-01

The main goals of this work are to characterize and investigate the potential wave sources of four mesospheric fronts identified in the hydroxyl near-infrared (OH-NIR) airglow images, obtained with an all-sky airglow imager installed at Comandante Ferraz Antarctic Station (EACF, as per its Portuguese acronym) located on King George Island in the Antarctic Peninsula. We identified and analyzed four mesospheric fronts in 2011 over King George Island. In addition, we investigate the atmospheric background environment between 80 and 100 km altitude and discuss the ducts and propagation conditions for these waves. For that, we used wind data obtained from a meteor radar operated at EACF and temperature data obtained from the TIMED/SABER satellite. The vertical wavenumber squared, m2, was calculated for each of the four waves. Even though no clearly defined duct (indicated by positive values of m2 sandwiched between layers above and below with m2 < 0) was found in any of the events, favorable propagation conditions for horizontal propagation of the fronts were found in three cases. In the fourth case, the wave front did not find any duct support and it appeared to dissipate near the zenith, transferring energy and momentum to the medium and, consequently, accelerating the wind in the wave propagation direction (near to south) above the OH peak (88-92 km). The likely wave sources for these four cases were investigated by using meteorological satellite images and in two cases we could find that strong instabilities were potential sources, i.e., a cyclonic activity and a large convective cloud cell. In the other two cases it was not possible to associate troposphere sources as potential candidates for the generation of such wave fronts observed in the mesosphere and secondary wave sources were attributed to these cases.

Gravity Wave Mixing and Effective Diffusivity for Minor Chemical Constituents in the Mesosphere/Lower Thermosphere

NASA Astrophysics Data System (ADS)

Grygalashvyly, M.; Becker, E.; Sonnemann, G. R.

2012-06-01

The influence of gravity waves (GWs) on the distributions of minor chemical constituents in the mesosphere-lower thermosphere (MLT) is studied on the basis of the effective diffusivity concept. The mixing ratios of chemical species used for calculations of the effective diffusivity are obtained from numerical experiments with an off-line coupled model of the dynamics and chemistry abbreviated as KMCM-MECTM (Kuehlungsborn Mechanistic general Circulation Model—MEsospheric Chemistry-Transport Model). In our control simulation the MECTM is driven with the full dynamical fields from an annual cycle simulation with the KMCM, where mid-frequency GWs down to horizontal wavelengths of 350 km are resolved and their wave-mean flow interaction is self-consistently induced by an advanced turbulence model. A perturbation simulation with the MECTM is defined by eliminating all meso-scale variations with horizontal wavelengths shorter than 1000 km from the dynamical fields by means of spectral filtering before running the MECTM. The response of the MECTM to GWs perturbations reveals strong effects on the minor chemical constituents. We show by theoretical arguments and numerical diagnostics that GWs have direct, down-gradient mixing effects on all long-lived minor chemical species that possess a mean vertical gradient in the MLT. Introducing the term wave diffusion (WD) and showing that wave mixing yields approximately the same WD coefficient for different chemical constituents, we argue that it is a useful tool for diagnostic irreversible transport processes. We also present a detailed discussion of the gravity-wave mixing effects on the photochemistry and highlight the consequences for the general circulation of the MLT.

El Niño-Southern Oscillation effect on quasi-biennial oscillations of temperature diurnal tides in the mesosphere and lower thermosphere

NASA Astrophysics Data System (ADS)

Sun, Yang-Yi; Liu, Huixin; Miyoshi, Yasunobu; Liu, Libo; Chang, Loren C.

2018-05-01

In this study, we evaluate the El Niño-Southern Oscillation (ENSO) signals in the two dominant temperature diurnal tides, diurnal westward wavenumber 1 (DW1) and diurnal eastward wavenumber 3 (DE3) on the quasi-biennial oscillation (QBO) scale (18-34 months) from 50 to 100 km altitudes. The tides are derived from the 21-year (January 1996-February 2017) Ground-to-Topside model of Atmosphere and Ionosphere for Aeronomy (GAIA) temperature simulations and 15-year (February 2002-February 2017) Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED)/Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) temperature observations. The results show that ENSO warm phases shorten the period ( 2 years) of the QBO in DW1 amplitude near the equator and DE3 amplitude at low latitudes of the Northern Hemisphere. In contrast, the QBO period lengthens ( 2.5 years) during the ENSO neutral and cold phases. Correlation analysis shows the long-lasting effect of ENSO on the tidal QBO in the mesosphere and lower thermosphere.[Figure not available: see fulltext.

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.

Long-term temperature observations from the troposphere to upper mesosphere over Mauna Loa, HI (19.5N, 155.6W) and Table Mountain, CA (34.4N, 117.7W) by JPL Lidars and nearby Radiosondes

NASA Astrophysics Data System (ADS)

Li, T.; Leblanc, T.; McDermid, S.; Wu, D. L.

2007-12-01

The JPL Rayleigh lidars at Mauna Loa Observatory (MLO), HI (19.5N, 155.6W) and Table Mountain Observatory (TMO), CA (34.4N, 117.7W) have been operated for the regular nighttime data acquisition of temperature since 1994 and 1989 respectively. Using the monthly mean temperature vertical profiles observed by the JPL lidars (35- 85km) and nearby radiosondes (5-30km), and with the linear regression analysis, we are able to extract the temperature trend, solar cycle, El Nino South Oscillation (ENSO), and Quasi-Biennial Oscillation (QBO) signals from the troposphere to upper mesosphere over MLO and TMO. The temperature trends show different behaviors at two sites, minor trend at MLO, but more negative trend at TMO. The solar cycle responses in temperature are generally positive above the middle stratosphere at both sites, but negative response at MLO and positive at TMO below. During the El Nino events, the warmer temperatures in the troposphere and upper mesosphere, and the colder temperatures in the stratosphere and lower mesosphere were observed at MLO and almost visa verse at TMO. The significant QBO oscillations were observed in the stratosphere with amplitudes of ~2-3K and with clearer downward phase progression at MLO than that at TMO. The mesospheric QBO near 75-85km is clearly present at both sites with amplitude of ~2K and with longer vertical wavelength than that in stratosphere. In addition, we calculated the GW variances using lidar temperature profiles with 30min and 1km resolutions in the upper stratosphere (38-50km) and lower mesosphere (50-62km), and nearby radiosondes in the lower stratosphere (18-30km). The monthly mean GW variances clearly show an annual oscillation with a maximum in the winter and minimum in the summer. The QBO signature could be clearly seen in the lower stratosphere. In the upper stratosphere, a longer period oscillation (~5-6 years) with maxima in 2000-2001 and 2006 was revealed to synchronize with the solar maximum and minimum

A numerical model of gravity wave breaking and stress in the mesosphere

NASA Technical Reports Server (NTRS)

Schoeberl, M. R.; Strobel, D. F.; Apruzese, J. P.

1983-01-01

The goal of the study is to calculate numerically the deceleration and heating caused by breaking gravity waves. The effect of the radiative dissipation of the wave is included as vertical-wavelength-dependent Newtonian cooling. The parameterization for zonal deceleration is extended by breaking gravity waves (Lindzen, 1981) to include the turbulent diffusion of heat and momentum. After describing the numerical model, the numerical results are presented and compared with the parameterizations in a noninteractive model of the mean zonal wind. Attention is then given to the transport of constituents by gravity waves and the attendant turbulent zone. It is noted that if gravity wave breaking were not an intermittent process, gravity wave stresses would produce an adiabatic mesosphere with a zonal mean velocity close to the phase speed of the breaking wave.

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.

Photoemission from sodium on ice: a mechanism for positive and negative charge coexistence in the mesosphere.

PubMed

Vondrak, Tomas; Plane, John M C; Meech, Stephen R

2006-03-09

Photoemission from sodium deposited on ice films is described. Deposition of 0.02 ML of sodium is found to dramatically reduce the threshold for photoemission from the ice film to (2.3+/-0.2) eV. Thus, the cross-section for photoemission reaches >10(-18) cm2 in the visible region of the spectrum. It is proposed that the initial state is a solvated electron on the ice surface, which is supported by optical transmission spectroscopy. The potential significance of these results in understanding unexplained charging phenomena in the mesosphere is discussed.

Mesospheric temperatures estimated from the meteor radar observations at Mohe, China

NASA Astrophysics Data System (ADS)

Liu, Libo; Liu, Huixin; Chen, Yiding; Le, Huijun

2017-04-01

In this work, we report the estimation of mesospheric temperatures at 90 km height from the observations of the VHF all-sky meteor radar operated at Mohe (53.5 °N, 122.3° E), China, since August 2011. The kinetic temperature profiles retrieved from the observations of Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) onboard the Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics (TIMED) satellite are processed to provide the temperature (TSABER) and temperature gradient (dT/dh) at 90 km height. Based on the SABER temperature profile data an empirical dT/dh model is developed for the Mohe latitude. First, we derive the temperatures from the meteor decay times (Tmeteor) and the Mohe dT/dh model gives prior information of temperature gradients. Secondly, the full-width of half maximum (FWHM) of the meteor height profiles is calculated and further used to deduce the temperatures (TFWHM) based on the strong linear relationship between FWHM and TSABER. The temperatures at 90 km deduced from the decay times (Tmeteor) and from the meteor height distributions (TFWHM) at Mohe are validated/calibrated with TSABER. The temperatures present a considerable annual variation, being maximum in winter and minimum in summer. Harmonic analyses reveal that the temperatures have an annual variation consistent with TSABER. Our work suggests that the FWHM has a good performance in routine estimation of the temperatures. It should be pointed out that the slope of FWHM and TSABER is 10.1 at Mohe, which is different from that of 15.71 at King Sejong (62.2° S, 58.8° E) station. Acknowledgments The TIMED/SABER kinetic temperature (version 2.0) data are provided by the SABER team through http://saber.gats-inc.com/. The temperatures from the NRLMSISE-00 model are calculated using Aerospace Blockset toolbox of MATLAB (2016a). This research was supported by National Natural Science Foundation of China (41231065, 41321003). We acknowledge the use of meteor radar

Influence of soil organic matter composition on the partition of organic compounds

USGS Publications Warehouse

Rutherford, D.W.; Chiou, C.T.; Klle, D.E.

1992-01-01

The sorption at room temperature of benzene and carbon tetrachloride from water on three high-organic-content soils (muck, peat, and extracted peat) and on cellulose was determined in order to evaluate the effect of sorbent polarity on the solute partition coefficients. The isotherms are highly linear for both solutes on all the organic matter samples, which is consistent with a partition model. For both solutes, the extracted peat shows the greatest sorption capacity while the cellulose shows the lowest capacity; the difference correlates with the polar-to-nonpolar group ratio [(O + N)/C] of the sorbent samples. The relative increase of solute partition coefficient (Kom) with a decrease of sample polar content is similar for both solutes, and the limiting sorption capacity on a given organic matter sample is comparable between the solutes. This observation suggests that one can estimate the polarity effect of a sample of soil organic matter (SOM) on Kom of various nonpolar solutes by determining the partition coefficient of single nonpolar solute when compositional analysis of the SOM is not available. The observed dependence of Kom on sample polarity is used to account for the variation of Kom values of individual compounds on different soils that results from change in the polar group content of SOM. On the assumption that the carbon content of SOM in "ordinary soils" is 53-63%, the calculated variation of Kom is a factor of ???3. This value is in agreement with the limit of variation of most Kom data with soils of relatively high SOM contents.

Planetary wave-gravity wave interactions during mesospheric inversion layer events

NASA Astrophysics Data System (ADS)

Ramesh, K.; Sridharan, S.; Raghunath, K.; Vijaya Bhaskara Rao, S.; Bhavani Kumar, Y.

2013-07-01

lidar temperature observations over Gadanki (13.5°N, 79.2°E) show a few mesospheric inversion layer (MIL) events during 20-25 January 2007. The zonal mean removed SABER temperature shows warm anomalies around 50°E and 275°E indicating the presence of planetary wave of zonal wave number 2. The MIL amplitudes in SABER temperature averaged for 10°N-15°N and 70°E-90°E show a clear 2 day wave modulation during 20-28 January 2007. Prior to 20 January 2007, a strong 2day wave (zonal wave number 2) is observed in the height region of 80-90 km and it gets largely suppressed during 20-26 January 2007 as the condition for vertical propagation is not favorable, though it prevails at lower heights. The 10 day mean zonal wind over Tirunelveli (8.7°N, 77.8°E) shows deceleration of eastward winds indicating the westward drag due to wave dissipation. The nightly mean MF radar observed zonal winds show the presence of alternating eastward and westward winds during the period of 20-26 January 2007. The two dimensional spectrum of Rayleigh lidar temperature observations available for the nights of 20, 22, and 24 January 2007 shows the presence of gravity wave activity with periods 18 min, 38 min, 38 min, and vertical wavelengths 6.4 km, 4.0 km, 6.4 km respectively. From the dispersion relation of gravity waves, it is inferred that these waves are internal gravity waves rather than inertia gravity waves with the horizontal phase speeds of ~40 m/s, ~37 m/s, and ~50 m/s respectively. Assuming the gravity waves are eastward propagating waves, they get absorbed only in the eastward local wind fields of the planetary wave thereby causing turbulence and eddy diffusion which can be inferred from the estimation of large drag force due to the breaking of gravity wave leading to the formation of large amplitude inversion events in alternate nights. The present study shows that, the mesospheric temperature inversion is caused mainly due to the gravity wave breaking and the inversion

Chemistry of Singlet Oxygen [O2(a1DELTAg)] in the Upper Atmosphere

DTIC Science & Technology

2012-02-06

mesosphere and stratosphere, J. Atmos. Sci., 37, 1342-1357. Kalashnikova, O., M. Horanyi, G. E. Thomas , and O. B. Toon (2000), Meteoric Smoke production in...Approved for public release; distribution is unlimitd. 17 Midey, A. J., I. Dotan, J. V. Seeley , and A. A. Viggiano (2009), Reactions of Small Negative...P., M. T. DeLand, G. E. Thomas , and J. J. Olivero (2009), Long term variation in the frequency of polar mesospheric clouds in the Northern Hemisphere

Trends and Solar Cycle Effects in Temperature Versus Altitude From the Halogen Occultation Experiment for the Mesosphere and Upper Stratosphere

NASA Technical Reports Server (NTRS)

Remsberg, Ellis E.

2009-01-01

Fourteen-year time series of mesospheric and upper stratospheric temperatures from the Halogen Occultation Experiment (HALOE) are analyzed and reported. The data have been binned according to ten-degree wide latitude zones from 40S to 40N and at 10 altitudes from 43 to 80 km-a total of 90 separate time series. Multiple linear regression (MLR) analysis techniques have been applied to those time series. This study focuses on resolving their 11-yr solar cycle (or SC-like) responses and their linear trend terms. Findings for T(z) from HALOE are compared directly with published results from ground-based Rayleigh lidar and rocketsonde measurements. SC-like responses from HALOE compare well with those from lidar station data at low latitudes. The cooling trends from HALOE also agree reasonably well with those from the lidar data for the concurrent decade. Cooling trends of the lower mesosphere from HALOE are not as large as those from rocketsondes and from lidar station time series of the previous two decades, presumably because the changes in the upper stratospheric ozone were near zero during the HALOE time period and did not affect those trends.

Atmospheric Gravity Waves and Turbulent Processes in the Mesopause Region Based on PMSE MAARSY Observations

NASA Astrophysics Data System (ADS)

Gudadze, N.; Chau, J. L.; Stober, G.; Latteck, R.

2016-12-01

Mesosphere-lower-thermosphere (MLT) polar dynamics are interesting and important subject for study in atmospheric physic. It is considered that mesopause region is where the main part of the Atmospheric gravity waves breaks and/or dissipates. However this region is difficult to observe. Continuous Observations of the polar summer mesosphere with the Middle Atmosphere Alomar Radar System (MAARSY) and its predecessor the ALOMAR-Wind-Radar (ALWIN) (before 2010), have been used to investigate dynamical structures of well-known phenomenon - Polar Mesosphere Summer Echoes (PMSE) which is an important tracer in the summer polar mesopause region. Signal to Noise Ratio (SNR) and Doppler radial velocity from the PMSE are used to investigate the wave-like motions with periods larger than 5 minutes. Such oscillations are studied in terms of atmospheric gravity waves (AGWs). Processes also connected with AGWs as PMSE layering, are studied in connection with the background conditions of the neutral atmosphere as well. Background winds are obtained from collocated meteor radar (MR). We used local enhancement method for the processing of altitude-time SNR images to detect layers in the PMSEs and characterised them. Our preliminary results indicate that PMSE strength and behaviour is correlated with the meridional wind. Furthermore we found that the spectral width (SW), which is a proxy of turbulence, is most of the time weakly dependent on SNR strength. However, there are some events where SW is highly dependent on SNR intensity indicating that they could be associated to turbulent-dominated events.

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.

Polarization of photons in matter–antimatter annihilation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moskaliuk, S.S.

2015-03-10

In this work we demonstrate the possibility of generation of linear polarization of the electromagnetic field (EMF) due to the quantum effects in matter-antimatter annihilation process for anisotropic space of the I type according to Bianchi. We study the dynamics of this process to estimate the degree of polarisation of the EMF in the external gravitational field of the anisotropic Bianchi I model. It has been established that the quantum effects in matter-antimatter annihilation process in the external gravitational field of the anisotropic Bianchi I model provide contribution to the degree of polarisation of the EMF in quadrupole harmonics.

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.

Aeronomy of Ice in the Mesosphere Mission Overview and Collaborative Studies Using the AIM and TIMED Data Sets

NASA Astrophysics Data System (ADS)

Rusell, J. M.; Bailey, S. M.; Rusch, D.; Gordley, L. L.; Hervig, M. E.; Merkel, A.

2007-12-01

The Aeronomy of Ice in the Mesosphere (AIM) mission was launched from Vandenberg Air Force Base in California on April 25, 2007 becoming the first satellite mission dedicated to the study of noctilucent clouds that occur at approximately 83km altitude. A Pegasus XL rocket launched the satellite into a near perfect 600 km sun synchronous circular orbit. AIM carries three instruments - a nadir imager, a solar occultation instrument and an in-situ cosmic dust detector - that were specifically selected because of their ability to provide key measurements needed to address the six AIM science objectives. The Thermosphere Ionosphere Mesosphere Energetics and Dynamics mission was launched from Vandenberg Air Force Base on December 7, 2001 and is dedicated to the study of the structure, chemistry, energetics and dynamics of the atmospheric region between 60 km and 180 km altitude. TIMED carries four instruments including an infrared limb sounder to characteristic the temperature, chemistry, energetics and dynamics of the region; a global ultraviolet imager; a solar flux monitor and an instrument to measure winds. Together AIM and TIMED form an important component of the Heliophysics Great Observatory. This paper will provide an overview of the AIM mission and will discuss collaborative studies using the combined AIM/TIMED data sets in a synergistic way to advance our knowledge of this region where the sun first interacts with Earth's atmosphere.

Temperature responses to the 11 year solar cycle in the mesosphere from the 31 year (1979-2010) extended Canadian Middle Atmosphere Model simulations and a comparison with the 14 year (2002-2015) TIMED/SABER observations

NASA Astrophysics Data System (ADS)

Gan, Quan; Du, Jian; Fomichev, Victor I.; Ward, William E.; Beagley, Stephen R.; Zhang, Shaodong; Yue, Jia

2017-04-01

A recent 31 year simulation (1979-2010) by extended Canadian Middle Atmosphere Model (eCMAM30) and the 14 year (2002-2015) observation by the Thermosphere Ionosphere Mesosphere and Dynamics/Sounding of the Atmosphere using Broadband Emssion Radiometry (TIMED/SABER) are utilized to investigate the temperature response to the 11 year solar cycle on the mesosphere. Overall, the zonal mean responses tend to increase with height, and the amplitudes are on the order of 1-2 K/100 solar flux unit (1 sfu = 10-22 W m-2 Hz-1) below 80 km and 2-4 K/100 sfu in the mesopause region (80-100 km) from the eCMAM30, comparatively weaker than those from the SABER except in the midlatitude lower mesosphere. A pretty good consistence takes place at around 75-80 km with a response of 1.5 K/100 sfu within 10°S/N. Also, a symmetric pattern of the responses about the equator agrees reasonably well between the two. It is noteworthy that the eCMAM30 displays an alternate structure with the upper stratospheric cooling and the lower mesospheric warming at midlatitudes of the winter hemisphere, in favor of the long-term Rayleigh lidar observation reported by the previous studies. Through diagnosing multiple dynamical parameters, it is manifested that this localized feature is induced by the anomalous residual circulation as a consequence of the wave-mean flow interaction during the solar maximum year.

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.

The Mesospheric Sodium Layer as a Remotely, Optically Pumped Magnetometer for Investigation of Birkeland Currents

NASA Astrophysics Data System (ADS)

Matzka, J.; Johnsen, M. G.; Hoppe, U. P.; Serrano, A.

2016-12-01

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.

Interferometric observations of the J(0,1) CO line on Venus: Upper mesospheric winds and CO abundance

NASA Astrophysics Data System (ADS)

Shah, Kathryn Pierce

1992-01-01

In 1988, we observed Venus with the millimeter interferometer at the Owens Valley Radio Astronomy Observatory at 115.2712 GHz, the first rotational transition of CO-12. The 33.4 inches diameter disk was spatially resolved by a synthesized beam having a full-width-half-maximum of 2.8 inches. Local time ranged from afternoon on the eastern limb, 2 PM, to just past midnight on the western limb, 12:30 AM. The CO absorption line was finely resolved in frequency by two 32-channel filterbanks having channel widths of 50 kHz and 1 MHz. The 1 MHz and 50 kHz filterbank data were merged to examine the entire CO line. These spectra show a decided local time dependency, becoming progressively deeper from the afternoon to the evening hours. A constrained least-squares inversion algorithm was used to solve for local CO mixing ratio profiles. The resultant profiles appear constant with height at several 10-5 in the late afternoon hours but increase from 10-4 at 80 km to 10-3 at 100 km in the night hours. The highest CO abundances occurred after local 10 PM and centered about the equator between 40 deg N and 40 deg S. This CO distribution fulfills predictions from research based on disk-average CO spectra and photochemical models. Only the late afternoon profiles are surprising, showing small CO abundances rather than expected moderate CO abundances via dayside photodissociation of CO2. The 50 KHz filterbank resolved the inner core of the CO absorption line. This yielded the first measurement of Doppler shifts across Venus caused by strong winds in the upper mesosphere. Calculated weighting functions showed sampling of the mesosphere over a 12 km layer centered at roughly 99 km. The Doppler shifts have a signature which matches that of westward, horizontal winds--being strongly 'blue' on the east/dayside limb, zero near the center, and strongly 'red' on the west/nightside limb of the planet disk. Smoothed wind measurements were best fitted in a least squares sense for a mean zonal

Vector dark matter annihilation with internal bremsstrahlung

DOE PAGES

Bambhaniya, Gulab; Kumar, Jason; Marfatia, Danny; ...

2017-01-10

We consider scenarios in which the annihilation of self-conjugate spin-1 dark matter to a Standard Model fermion-antifermion final state is chirality suppressed, but where this suppression can be lifted by the emission of an additional photon via internal bremsstrahlung. We find that this scenario can only arise if the initial dark matter state is polarized, which can occur in the context of self-interacting dark matter. In particular, this is possible if the dark matter pair forms a bound state that decays to its ground state before the constituents annihilate. We show that the shape of the resulting photon spectrum ismore » the same as for self-conjugate spin-0 and spin-1/2 dark matter, but the normalization is less heavily suppressed in the limit of heavy mediators.« less

Ground-based microwave radiometry to determine stratospheric and mesospheric ozone profiles

NASA Astrophysics Data System (ADS)

Lobsiger, E.

1987-05-01

From April 1984 to April 1985 a microwave radiometer was operated at Bern measuring the thermal emission of the rotational ozone transition at 142.2 GHz to determine stratospheric and mesospheric ozone abundances in the range 25-75 km altitude. From a total of 334 retrieved daytime profiles, monthly mean ozone partial pressures for Umkehr layers 6-10 were calculated. On this basis ozone variations compare favorably with Umkehr data from the nearby Arosa station and with a monthly zonal mean model compiled from satellite data by Keating and Young (1985). From the microwave data, an annual mean ozone distribution was determined. The method retrieves somewhat larger ozone volume mixing ratios between 25 and 30 km altitude. For the rest of the measurement range of the sensor there is good agreement with 20-year annual mean ozone values from Arosa, with the Krueger and Minzner profile and with the respective annual mean data given by Keating and Young.

Climatology and trends of mesospheric (58-90) temperatures based upon 1982-1986 SME limb scattering profiles

NASA Technical Reports Server (NTRS)

Clancy, R. Todd; Rusch, David W.

1989-01-01

Atmospheric temperature profiles for the altitude range 58-90 km were calculated using data on global UV limb radiances from the SME satellite. The major elements of this climatology include a high vertical resolution (about 4 km) and the coverage of the 70-90 km altitude region. The analysis of this extensive data set provides a global definition of mesospheric-lower thermospheric temperature trends over the 1982-1986 period. The observations suggest a pattern of 1-2 K/year decreases in temperatures at 80-90-km altitudes accompanied by 0.5-1.5 K/year increases in temperatures at 65-80-km altitudes.

Resolving the mesospheric nighttime 4.3 µm emission puzzle: comparison of the CO2(ν3) and OH(ν) emission models

NASA Astrophysics Data System (ADS)

Panka, Peter A.; Kutepov, Alexander A.; Kalogerakis, Konstantinos S.; Janches, Diego; Russell, James M.; Rezac, Ladislav; Feofilov, Artem G.; Mlynczak, Martin G.; Yiğit, Erdal

2017-08-01

In the 1970s, the mechanism of vibrational energy transfer from chemically produced OH(ν) in the nighttime mesosphere to the CO2(ν3) vibration, OH(ν) ⇒ N2(ν) ⇒ CO2(ν3), was proposed. In later studies it was shown that this "direct" mechanism for simulated nighttime 4.3 µm emissions of the mesosphere is not sufficient to explain space observations. In order to better simulate these observations, an additional enhancement is needed that would be equivalent to the production of 2.8-3 N2(1) molecules instead of one N2(1) molecule in each quenching reaction of OH(ν) + N2(0). Recently a new "indirect" channel of the OH(ν) energy transfer to N2(ν) vibrations, OH(ν) ⇒ O(1D) ⇒ N2(ν), was suggested and then confirmed in a laboratory experiment, where its rate for OH(ν = 9) + O(3P) was measured. We studied in detail the impact of the "direct" and "indirect" mechanisms on CO2(ν3) and OH(ν) vibrational level populations and emissions. We also compared our calculations with (a) the SABER/TIMED nighttime 4.3 µm CO2 and OH 1.6 and 2.0 µm limb radiances of the mesosphere-lower thermosphere (MLT) and (b) with ground- and space-based observations of OH(ν) densities in the nighttime mesosphere. We found that the new "indirect" channel provides a strong enhancement of the 4.3 µm CO2 emission, which is comparable to that obtained with the "direct" mechanism alone but assuming an efficiency that is 3 times higher. The model based on the "indirect" channel also produces OH(ν) density distributions which are in good agreement with both SABER limb OH emission observations and ground and space measurements. This is, however, not true for the model which relies on the "direct" mechanism alone. This discrepancy is caused by the lack of an efficient redistribution of the OH(ν) energy from higher vibrational levels emitting at 2.0 µm to lower levels emitting at 1.6 µm. In contrast, the new  indirect  mechanism efficiently removes at least five

Solar Mesosphere Explorer satellite measurements of el Chichon stratospheric aerosols. 1: Cloud morphology

NASA Technical Reports Server (NTRS)

Rusch, D. W.; Clancy, R. T.; Eparvier, F. G.; Thomas, G. E.; Thomas, R. J.

1994-01-01

Data from the Solar Mesosphere Explorer (SME) is used to track the time, latitude, and altitude (above 18 km) development of the aerosol cloud injected into the stratosphere by the eruption of el Chichon. This unique data set, using scattering data from the near-infrared (1.27 and 1.87 microns) and visible (440 nm) spectrometers on SME, covers the period from the initial injection in April 1982 through the end of 1986. Although the bulk of the mass is contained in the latitude band from 10 deg S to 30 deg N for the entire duration of the measurements, transport of material to high latitudes is apparent in the data in the post eruption period. The times aerosol density maxima vary greatly as a function of altitude and latitude.

Vacuum polarization near a distorted black hole

NASA Astrophysics Data System (ADS)

Frolov, V. P.; Alberto García, D.

1983-12-01

The vacuum polarization near a black hole distorted by the axially symmetric gravitational field of external matter is studied. The explicit expression for <φ2> at the pole of the distorted horizon is obtained. Also at Sección de Graduados, Escuela Superior de Ingeniería Mecánica y Eléctrica del IPN, México DF, México.

Using Meteoric Ablation to Constrain Vertical Transport in the Upper Mesosphere

NASA Astrophysics Data System (ADS)

Plane, J. M. C.; Carrillo-Sánchez, J. D.; Nesvorny, D.; Pokorný, P.; Janches, D.

2016-12-01

Meteoric ablation injects a variety of metals into the upper mesosphere and lower thermosphere, giving rise to layers of metal atoms centered around 90 km. The Na, Fe, K and Ca atom densities are measured accurately using resonance lidars. Since the reaction kinetics of many of the chemical reactions which produce these layers have now been studied in the laboratory, chemistry modules for each of the metals have been developed with a reasonable degree of confidence. When these modules are put into a global high-top model such as NCAR's Whole Atmosphere Community Climate Model (WACCM), a major problem emerges: the injection flux of each of the metals, termed the Meteoric Input Function (MIF), has to be reduced substantially in order to model the observed metal atom densities. For instance, the Na and Fe MIFs need to be reduced by factors of 8 and 14, respectively, compared with the MIFs determined from the lidar-measured vertical fluxes of Na and Fe atoms. The accumulation of meteoric smoke particles in polar ice cores also indicates that the meteoric ablation flux is significantly larger that can be handled in models where vertical transport is solely due to eddy diffusional mixing. Here we derive new Na and Fe MIFs by determining the relative contributions of the known dust sources in the near-Earth environment: Jupiter Family Comets (JFCs), the main asteroid belt, Halley Type comets, and Oort Cloud comets. The mass/velocity/radiant distributions of these cosmic dust populations are Monte Carlo sampled and the elemental ablation rates calculated with the Leeds Chemical Ablation Model. The contribution of each dust source in the Earth's atmosphere is then determined by fitting the measured cosmic spherule accretion rate at the South Pole, and the measured vertical Na and Fe fluxes above 86 km. We conclude that JFCs contribute either 85% or 93% to the total incoming mass, depending on whether infra-red observations of the Zodiacal Dust Cloud by the IRAS or Planck

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

Silicon Chemistry in the Mesosphere and Lower Thermosphere

NASA Technical Reports Server (NTRS)

Plane, John M. C.; Gomez-Martin, Juan Carlos; Feng, Wuhu; Janches, Diego

2016-01-01

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 S(exp +). 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(exp +)Fe(exp +) ratio are shown to be in good agreement with rocket-borne mass spectrometric measurements between 90 and 110 km. Si(exp +) 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 the irrelative 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.

In-flight calibration of mesospheric rocket plasma probes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Havnes, Ove; University Studies Svalbard; Hartquist, Thomas W.

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 effectivemore » 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.« less

Earth Limb taken by the Expedition 17 Crew

NASA Image and Video Library

2008-07-22

ISS017-E-011603 (22 July 2008) --- Layers of Earth's atmosphere, brightly colored as the sun rises over central Asia, and Polar Mesospheric Clouds (also known as noctilucent clouds) are featured in this image photographed by an Expedition 17 crewmember on the International Space Station. The image was acquired in support of International Polar Year research.

Particle Events as a Possible Source of Large Ozone Loss during Magnetic Polarity Transitions

NASA Technical Reports Server (NTRS)

vonKoenig, M.; Burrows, J. P.; Chipperfield, M. P.; Jackman, C. H.; Kallenrode, M.-B.; Kuenzi, K. F.; Quack, M.

2002-01-01

The energy deposition in the mesosphere and stratosphere during large extraterrestrial charged particle precipitation events has been known for some time to contribute to ozone losses due to the formation of potential ozone destroying species like NO(sub x), and HO(sub x). These impacts have been measured and can be reproduced with chemistry models fairly well. In the recent past, however, even the impact of the largest solar proton events on the total amount of ozone has been small compared to the dynamical variability of ozone, and to the anthropogenic induced impacts like the Antarctic 'ozone hole'. This is due to the shielding effect of the magnetic field. However, there is evidence that the earth's magnetic field may approach a reversal. This could lead to a decrease of magnetic field strength to less than 25% of its usual value over a period of several centuries . We show that with realistic estimates of very large solar proton events, scenarios similar to the Antarctic ozone hole of the 1990s may occur during a magnetic polarity transition.

Gravity Wave Interactions with Fine Structures in the Mesosphere and Lower Thermosphere

NASA Astrophysics Data System (ADS)

Mixa, Tyler; Fritts, David; Bossert, Katrina; Laughman, Brian; Wang, Ling; Lund, Thomas; Kantha, Lakshmi

2017-04-01

An anelastic numerical model is used to probe the influences of fine layering structures on gravity wave propagation in the Mesosphere and Lower Thermosphere (MLT). Recent lidar observations confirm the presence of persistent layered structures in the MLT that have sharp stratification and vertical scales below 1km. Gravity waves propagating through finely layered environments can excite and modulate the evolution of small scale instabilities that redefine the layering structure in these regions. Such layers in turn filter the outgoing wave spectra, promote ducting or reflection, hasten the onset of self-acceleration dynamics, and encourage wave/mean-flow interactions via energy and momentum transport. Using high resolution simulations of a localized gravity wave packet in a deep atmosphere, we identify the relative impacts of various wave and mean flow parameters to improve our understanding of these dynamics and complement recent state-of-the-art observations.

One-step solution fabrication of magnetic chains consisting of jingle-bell-shaped cobalt mesospheres

NASA Astrophysics Data System (ADS)

Liang, Fang; Guo, Lin; Zhong, QunPeng; Wen, Xiaogang; Yang, Shihe; Zheng, Wangzhi; Chen, Chinping; Zhang, Nina; Chu, Weiguo

2006-09-01

Using a one-step solution phase approach, the authors have synthesized uniform jingle bell-shaped cobalt mesopheres (550-750nm) and assembled the mesospheres into long magnetic chains (20-30μm). All of the cobalt spheres are hollow with ˜40nm thick shells but each contains an ˜200nm diameter solid ball. The nano- to mesoscale structures were realized via reaction of CoCl2•6H2O and N2H4•H2O in the presence of polyvinylpyrrolidone (PVP) in an ethylene glycol solution. Magnetic measurements show a coercivity of about 75Oe with a remnance of 9.6emu /g at 300K. We propose a possible mechanism for the formation of the nanoto mesoscale structures.

Magnetic compound refractive lens for focusing and polarizing cold neutron beams.

PubMed

Littrell, K C; te Velthuis, S G E; Felcher, G P; Park, S; Kirby, B J; Fitzsimmons, M R

2007-03-01

Biconcave cylindrical lenses are used to focus beams of x rays or neutrons using the refractive properties of matter. In the case of neutrons, the refractive properties of magnetic induction can similarly focus and simultaneously polarize the neutron beam without the concomitant attenuation of matter. This concept of a magnetic refractive lens was tested using a compound lens consisting of 99 pairs of cylindrical permanent magnets. The assembly successfully focused the intensity of a white beam of cold neutrons of one spin state at the detector, while defocusing the other. This experiment confirmed that a lens of this nature may boost the intensity locally by almost an order of magnitude and create a polarized beam. An estimate of the performance of a more practically dimensioned device suitable for incorporation in reflectometers and slit-geometry small angle scattering instruments is given.

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.

2015-07-01

An algorithm has been developed for the retrieval of sodium atom (Na) number density on a latitude and altitude grid from SCIAMACHY 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 analysed. 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. The Na layer has a nearly constant altitude of 90-93 km for all latitudes and seasons, and has a full width at half maximum of 5-15 km. Small but substantial seasonal variations in Na are identified for latitudes less than 40°, where the maximum Na number densities are 3000-4000 atoms cm-3. At mid 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 mid latitudes. The results are compared with other observations and models and there is overall a good agreement with these.

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.

Modeling and parameterization of photoelectrons emitted in condensed matter by linearly polarized synchrotron radiation

NASA Astrophysics Data System (ADS)

Jablonski, A.

2018-01-01

Growing availability of synchrotron facilities stimulates an interest in quantitative applications of hard X-ray photoemission spectroscopy (HAXPES) using linearly polarized radiation. An advantage of this approach is the possibility of continuous variation of radiation energy that makes it possible to control the sampling depth for a measurement. Quantitative applications are based on accurate and reliable theory relating the measured spectral features to needed characteristics of the surface region of solids. A major complication in the case of polarized radiation is an involved structure of the photoemission cross-section for hard X-rays. In the present work, details of the relevant formalism are described and algorithms implementing this formalism for different experimental configurations are proposed. The photoelectron signal intensity may be considerably affected by variation in the positioning of the polarization vector with respect to the surface plane. This information is critical for any quantitative application of HAXPES by polarized X-rays. Different quantitative applications based on photoelectrons with energies up to 10 keV are considered here: (i) determination of surface composition, (ii) estimation of sampling depth, and (iii) measurements of an overlayer thickness. Parameters facilitating these applications (mean escape depths, information depths, effective attenuation lengths) were calculated for a number of photoelectron lines in four elemental solids (Si, Cu, Ag and Au) in different experimental configurations and locations of the polarization vector. One of the considered configurations, with polarization vector located in a plane perpendicular to the surface, was recommended for quantitative applications of HAXPES. In this configurations, it was found that the considered parameters vary weakly in the range of photoelectron emission angles from normal emission to about 50° with respect to the surface normal. The averaged values of the mean

Earth Observation taken by STS-117 crewmember on Space Shuttle Atlantis

NASA Image and Video Library

2007-06-10

S117-E-06998 (10 June 2007) --- Polar Mesospheric Clouds are featured in this image photographed by a STS-117 crewmember onboard Space Shuttle Atlantis. Sometimes in the summertime in the far northern (or southern) latitudes, high in the Earth's atmosphere at the edge of space, thin silvery clouds form and are observed just after sunset. These high clouds, occurring at altitudes of about 80 kilometers (50 miles), are called Polar Mesospheric Clouds (PMC) or noctilucent clouds, and are the subject of new studies to determine whether their occurrence is related to global climate change. Observations over the past few years suggest that PMC are now observed more frequently and at lower latitudes than historical observations. Several studies related to the International Polar Year (IPY), and the AIM (Aeronomy of Ice in the Mesosphere) spacecraft are underway to collect relevant data on the chemistry and physics of the mesosphere that might explain the occurrence of PMC. Astronauts in orbiting spacecraft frequently observe PMC over Canada, northern Europe and Asia during June, July and August. While PMC also occur over the high latitudes in the southern hemisphere in December, January and February, astronaut observations of southern PMC are less frequent. Earlier in June 2007, the shuttle crew visiting the International Space Station observed spectacular PMC over north-central Asia. This image was taken looking north while the shuttle and station were docking and flying over the border between western China, Mongolia and Kazakhstan. The red-to-dark region at the bottom of the image is the dense part of the Earth's atmosphere. Because this image was taken with a long lens (180mm), the entire profile of the Earth's limb is not captured. To support IPY research over the next 2 years, station crewmembers will be looking for and documenting PMC in both hemispheres.

Interface control of bulk ferroelectric polarization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, P; Luo, Weidong; Yi, D.

2012-01-01

The control of material interfaces at the atomic level has led to no- vel interfacial properties and functionalities. In particular, the study of polar discontinuities at interfaces between complex oxides lies at the frontier of modern condensed matter research. Here we em- ploy a combination of experimental measurements and theoretical calculations to demonstrate the control of a bulk property, namely ferroelectric polarization, of a heteroepitaxial bilayer by precise atomic-scale interface engineering. More specifically, the control is achieved by exploiting the interfacial valence mismatch to influence the electrostatic potential step across the interface, which manifests itself as the biased-voltage in ferroelectricmore » hysteresis loops and determines the ferroelectric state. A broad study of diverse systems comprising different ferroelectrics and conducting perovskite un- derlayers extends the generality of this phenomenon.« less

The Response of the Southern Hemisphere Middle Atmosphere to the Madden-Julian oscillation during Austral Winter Using the Specified-Dynamics Whole Atmosphere Community Climate Model

NASA Astrophysics Data System (ADS)

Yang, C.; Li, T.; Smith, A. K.; Dou, X.

2017-12-01

Using the Specified-Dynamic (SD) Whole Atmosphere Community Climate Model (WACCM), we investigated the effects of the Madden-Julian oscillation (MJO) on the mid-winter stratosphere and mesosphere in the southern hemisphere (SH). The most significant responses of the SH polar cap temperature to the MJO are found 30 days after MJO Phase 1 (P1) and 10 days after the MJO Phase 5 (P5) in both the ERA-interim reanalysis and the SD-WACCM simulation. The 200 and 500 hPa geopotential height anomalies in the SH reveal that wave trains emanate from the Indian and Pacific Oceans when the MJO convection is enhanced in the eastern Indian Ocean and the western Pacific. As a result, the upward propagation and dissipation of planetary waves (PWs) in the mid- and high- latitude of the SH stratosphere is significantly enhanced, the Brewer-Dobson (BD) circulation in the SH stratosphere strengthens, and temperatures in the SH polar stratosphere increase. Wavenumber 1 in the stratosphere is the dominant component of the PW perturbation induced by the MJO convection. Filtering by the modified SH stratospheric winds alters the gravity waves (GWs) that propagate to the mesosphere. The dissipation and breaking of these waves causes anomalous downwelling in the mid- and high- latitudes of the mesosphere. The circulation changes, in turn, result in significant anomalous cooling in the mesosphere in response to MJO P1 and P5 at lags of 10 days and 30 days, respectively.

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).

Primordial features and Planck polarization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hazra, Dhiraj Kumar; Smoot, George F.; Shafieloo, Arman

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 inflationarymore » 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 χ{sup 2} 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).« less

Near InfraRed Imaging Spectrograph (NIRIS) for ground-based mesospheric OH(6-2) and O2(0-1) intensity and temperature measurements

NASA Astrophysics Data System (ADS)

Singh, Ravindra P.; Pallamraju, Duggirala

2017-08-01

This paper describes the development of a new Near InfraRed Imaging Spectrograph (NIRIS) which is capable of simultaneous measurements of OH(6-2) Meinel and O2(0-1) atmospheric band nightglow emission intensities. In this spectrographic technique, rotational line ratios are obtained to derive temperatures corresponding to the emission altitudes of 87 and 94 km. NIRIS has been commissioned for continuous operation from optical aeronomy observatory, Gurushikhar, Mount Abu (24.6°N, 72.8°E) since January 2013. NIRIS uses a diffraction grating of 1200 lines mm^{-1} and 1024× 1024 pixels thermoelectrically cooled CCD camera and has a large field-of-view (FOV) of 80° along the slit orientation. The data analysis methodology adopted for the derivation of mesospheric temperatures is also described in detail. The observed NIRIS temperatures show good correspondence with satellite (SABER) derived temperatures and exhibit both tidal and gravity waves (GW) like features. From the time taken for phase propagation in the emission intensities between these two altitudes, vertical phase speed of gravity waves, cz, is calculated and along with the coherent GW time period `τ ', the vertical wavelength, λ z, is obtained. Using large FOV observations from NIRIS, the meridional wavelengths, λ y, are also calculated. We have used one year of data to study the possible cause(s) for the occurrences of mesospheric temperature inversions (MTIs). From the statistics obtained for 234 nights, it appears that in situ chemical heating is mainly responsible for the observed MTIs than the vertical propagation of the waves. Thus, this paper describes a novel near infrared imaging spectrograph, its working principle, data analysis method for deriving OH and O2 emission intensities and the corresponding rotational temperatures at these altitudes, derivation of gravity wave parameters (τ , cz, λ z, and λ y), and results on the statistical study of MTIs that exist in the earth's mesospheric

Lidar measurements of mesospheric temperature inversion at a low latitude

NASA Astrophysics Data System (ADS)

Siva Kumar, V.; Bhavani Kumar, Y.; Raghunath, K.; Rao, P. B.; Krishnaiah, M.; Mizutani, K.; Aoki, T.; Yasui, M.; Itabe, T.

2001-08-01

The Rayleigh lidar data collected on 119 nights from March 1998 to February 2000 were used to study the statistical characteristics of the low latitude mesospheric temperature inversion observed over Gadanki (13.5° N, 79.2° E), India. The occurrence frequency of the inversion showed semiannual variation with maxima in the equinoxes and minima in the summer and winter, which was quite different from that reported for the mid-latitudes. The peak of the inversion layer was found to be confined to the height range of 73 to 79 km with the maximum occurrence centered around 76 km, with a weak seasonal dependence that fits well to an annual cycle with a maximum in June and a minimum in December. The magnitude of the temperature deviation associated with the inversion was found to be as high as 32 K, with the most probable value occurring at about 20 K. Its seasonal dependence seems to follow an annual cycle with a maximum in April and a minimum in October. The observed characteristics of the inversion layer are compared with that of the mid-latitudes and discussed in light of the current understanding of the source mechanisms.

Temperature estimation from hydroxyl airglow emission in the Venus night side mesosphere

NASA Astrophysics Data System (ADS)

Migliorini, A.; Snels, M.; Gérard, J.-C.; Soret, L.; Piccioni, G.; Drossart, P.

2018-01-01

The temperature of the night side of Venus at about 95 km has been determined by using spectral features of the hydroxyl airglow emission around 3 μm, recorded from July 2006 to July 2008 by VIRTIS onboard Venus Express. The retrieved temperatures vary from 145.5 to about 198.1 K with an average value of 176.3 ± 14.3 K and are in good agreement with previous ground-based and space observations. The variability with respect to latitude and local time has been studied, showing a minimum of temperature at equatorial latitudes, while temperature values increase toward mid latitudes with a local maximum at about 35°N. The present work provides an independent contribution to the temperature estimation in the transition region between the Venus upper mesosphere and the lower thermosphere, by using the OH emission as a thermometer, following the technique previously applied to the high-resolution O2(a1Δg) airglow emissions observed from ground.

Direct Probing of Polarization Charge at Nanoscale Level

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kwon, Owoong; Seol, Daehee; Lee, Dongkyu

Ferroelectric materials possess spontaneous polarization that can be used for multiple applications. Owing to a long-term development of reducing the sizes of devices, the preparation of ferroelectric materials and devices is entering the nanometer-scale regime. In order to evaluate the ferroelectricity, there is a need to investigate the polarization charge at the nanoscale. Nonetheless, it is generally accepted that the detection of polarization charges using a conventional conductive atomic force microscopy (CAFM) without a top electrode is not feasible because the nanometer-scale radius of an atomic force microscopy (AFM) tip yields a very low signal-to-noise ratio. But, the detection ismore » unrelated to the radius of an AFM tip and, in fact, a matter of the switched area. In this work, the direct probing of the polarization charge at the nanoscale is demonstrated using the positive-up-negative-down method based on the conventional CAFM approach without additional corrections or circuits to reduce the parasitic capacitance. The polarization charge densities of 73.7 and 119.0 µC cm -2 are successfully probed in ferroelectric nanocapacitors and thin films, respectively. The results we obtained show the feasibility of the evaluation of polarization charge at the nanoscale and provide a new guideline for evaluating the ferroelectricity at the nanoscale.« less

Production of odd nitrogen in the stratosphere and mesosphere - An intercomparison of source strengths

NASA Technical Reports Server (NTRS)

Jackman, C. H.; Frederick, J. E.; Stolarski, R. S.

1980-01-01

Galactic cosmic rays (GCRs), nuclear explosions, lightning, solar proton events (SPEs), relativistic electron precipitation, and meteors are related to the oxidation of nitrous oxide by comparing several sources of odd nitrogen (ON) in the stratosphere and mesosphere. Published O3 and N2O data show that ON produced by the reaction of O(1D) with N2O peaks between 25 and 35 km; the GCRs add approximately the same amount of ON as N2O oxidation at the solar minimum for geographic latitudes over 50 deg. Nuclear explosions in 1961-1962 added 1.1 and 2.2 x 10 to the 34th NO molecules each, and SPEs produced greater amounts of ON above 50 deg than N2O oxidation during 1958 through 1960, and in 1972.

Many-particle theory of nuclear systems with application to neutron star matter

NASA Technical Reports Server (NTRS)

Chakkalakal, D. A.; Yang, C. H.

1974-01-01

The energy-density relation was calculated for pure neutron matter in the density range relevant for neutron stars, using four different hard-core potentials. Calculations are also presented of the properties of the superfluid state of the neutron component, along with the superconducting state of the proton component and the effects of polarization in neutron star matter.

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

A Monte Carlo Study of Lambda Hyperon Polarization at BM@N

NASA Astrophysics Data System (ADS)

Suvarieva, D.; Gudima, K.; Zinchenko, A.

2018-03-01

Heavy strange objects (hyperons) can provide essential signatures of the excited and compressed baryonic matter. At NICA, it is planned to study hyperons both in the collider mode (MPD detector) and the fixed-target one (BM@N setup). Measurements of strange hyperon polarization can give additional information on the strong interaction mechanisms. In heavy-ion collisions, such measurements are even more valuable since the polarization is expected to be sensitive to characteristics of the QCD medium (vorticity, hydrodynamic helicity) and to QCD anomalous transport. In this analysis, the possibility to measure at BM@N the polarization of the lightest strange hyperon Λ is studied in Monte Carlo event samples of Au + Au collisions produced with the DCM-QGSM generator. It is shown that the detector will allow to measure polarization with a precision required to check the model predictions.

Northern Hemisphere Atmospheric Influence of the Solar Proton Events and Ground Level Enhancement in January 2005

NASA Technical Reports Server (NTRS)

Jackman, C. H.; Marsh, D. R.; Vitt, F. M.; Roble, R. G.; Randall, C. E.; Bernath, P. F.; Funke, B.; Lopez-Puertas, M.; Versick, S.; Stiller, G. P.;

Circularly polarized attosecond pulse generation and applications to ultrafast magnetism

NASA Astrophysics Data System (ADS)

Bandrauk, André D.; Guo, Jing; Yuan, Kai-Jun

2017-12-01

Attosecond science is a growing new field of research and potential applications which relies on the development of attosecond light sources. Achievements in the generation and application of attosecond pulses enable to investigate electron dynamics in the nonlinear nonperturbative regime of laser-matter interactions on the electron’s natural time scale, the attosecond. In this review, we describe the generation of circularly polarized attosecond pulses and their applications to induce attosecond magnetic fields, new tools for ultrafast magnetism. Simulations are performed on aligned one-electron molecular ions by using nonperturbative nonlinear solutions of the time-dependent Schrödinger equation. We discuss how bichromatic circularly polarized laser pulses with co-rotating or counter-rotating components induce electron-parent ion recollisions, thus producing circularly polarized high-order harmonic generation, the source of circularly polarized attosecond pulses. Ultrafast quantum electron currents created by the generated attosecond pulses give rise to attosecond magnetic field pulses. The results provide a guiding principle for producing circularly polarized attosecond pulses and ultrafast magnetic fields in complex molecular systems for future research in ultrafast magneto-optics.

Interferometric Observations of the J(0,1) Carbon Monoxide Line on Venus: Upper Mesospheric Winds and Carbon Monoxide Abundance

NASA Astrophysics Data System (ADS)

Shah, Kathryn Pierce

In 1988, we observed Venus with the millimeter interferometer at the Owens Valley Radio Astronomy Observatory at 115.2712 GHz, the first rotational transition of ^{12}CO. The 33."4 diameter disk was spatially resolved by a synthesized beam having a full -width-half-maximum of 2."8. Local time ranged from afternoon on the eastern limb, 2 PM, to just past midnight on the western limb, 12:30 AM. The CO absorption line was finely resolved in frequency by two 32-channel filterbanks having channel widths of 50 kHz and 1 MHz. The 1 MHz and 50 kHz filterbank data were merged to examine the entire CO line. These spectra show a decided local time dependency, becoming progressively deeper from the afternoon to the evening hours. A constrained least -squares inversion algorithm was used to solve for local CO mixing ratio profiles. The resultant profiles appear constant with height at several 10^{ -5} in the late afternoon hours but increase from 10^{-4} at 80 km to 10^{-3} at 100 km in the night hours. The highest CO abundances occurred after local 10 PM and centered about the equator between 40 ^circN and 40^circ S. This CO distribution fulfills predictions from research based on disk-average CO spectra and photochemical models. Only the late afternoon profiles are surprising, showing small CO abundances rather than expected moderate CO abundances via dayside photodissociation of CO _2. The 50 KHz filterbank resolved the inner core of the CO absorption line. This yielded the first measurement of doppler shifts across Venus caused by strong winds in the upper mesosphere. Calculated weighting functions showed sampling of the mesosphere over a 12 km layer centered at roughly 99 km. The doppler shifts have a signature which matches that of westward, horizontal winds--being strongly "blue" on the east/dayside limb, zero near the center and strongly "red" on the west/nightside limb of the planet disk. Smoothed wind measurements were best fitted in a least squares sense for a mean

Cosmological Parameters from the QUAD CMB Polarization Experiment

NASA Astrophysics Data System (ADS)

Castro, P. G.; Ade, P.; Bock, J.; Bowden, M.; Brown, M. L.; Cahill, G.; Church, S.; Culverhouse, T.; Friedman, R. B.; Ganga, K.; Gear, W. K.; Gupta, S.; Hinderks, J.; Kovac, J.; Lange, A. E.; Leitch, E.; Melhuish, S. J.; Memari, Y.; Murphy, J. A.; Orlando, A.; Pryke, C.; Schwarz, R.; O'Sullivan, C.; Piccirillo, L.; Rajguru, N.; Rusholme, B.; Taylor, A. N.; Thompson, K. L.; Turner, A. H.; Wu, E. Y. S.; Zemcov, M.; QUa D Collaboration

2009-08-01

In this paper, we present a parameter estimation analysis of the polarization and temperature power spectra from the second and third season of observations with the QUaD experiment. QUaD has for the first time detected multiple acoustic peaks in the E-mode polarization spectrum with high significance. Although QUaD-only parameter constraints are not competitive with previous results for the standard six-parameter ΛCDM cosmology, they do allow meaningful polarization-only parameter analyses for the first time. In a standard six-parameter ΛCDM analysis, we find the QUaD TT power spectrum to be in good agreement with previous results. However, the QUaD polarization data show some tension with ΛCDM. The origin of this 1σ-2σ tension remains unclear, and may point to new physics, residual systematics, or simple random chance. We also combine QUaD with the five-year WMAP data set and the SDSS luminous red galaxies 4th data release power spectrum, and extend our analysis to constrain individual isocurvature mode fractions, constraining cold dark matter density, αcdmi < 0.11 (95% confidence limit (CL)), neutrino density, αndi < 0.26 (95% CL), and neutrino velocity, αnvi < 0.23 (95% CL), modes. Our analysis sets a benchmark for future polarization experiments.

Simulation of the October-November 2003 solar proton event in the CMAM GCM: Comparison with observations

NASA Technical Reports Server (NTRS)

Semeniuk, K.; McConnell, J. C.; Jackman, C. H.

2005-01-01

The FTS instrument on SciSat-I observed a very large NO(x) anomaly in mid February of 2004 near 80 N in the lower mesosphere. It has been proposed that the most likely origin of the lower mesosphere anomaly in February is transport, from the lower thermosphere or upper mesosphere, of high levels of NO(x) associated with high levels of solar activity in 0ct.-Nov. 2003. There was no major solar flare activity during January and February to cause ionization in the mesosphere. Using a middle atmosphere GCM we investigate whether the NO(x) produced directly by the 0ct.-Nov. 2003 solar flares or indirectly via enhanced auroral ionization as a result of magnetospheric precipitation can explain the ACE observations. We find that the solar proton events associated with the solar explosions in 0ct.-Nov. 2003 produce insufficient amounts of NO(x), in the mesosphere and thermosphere (less than 2 ppm at 90 km) to give rise to the observed anomaly. However. there is evidence that intense aurorae caused by the 0ct.-Nov. 2003 solar storms produced thermospheric values of NO(x) reaching hundreds of ppm. The NO(x) created by the auroral particles appears to have lasted much longer than the immediate period of the 0ct.-Nov. 2003 solar storms. It appears that NO(x) rich air experienced confined polar night descent into the middle mesosphere during November and December, prior to the onset of the strong mesospheric vortex in January 2004.

On the construction of a direct numerical simulation of a breaking inertia-gravity wave in the upper mesosphere

NASA Astrophysics Data System (ADS)

Fruman, Mark D.; Remmler, Sebastian; Achatz, Ulrich; Hickel, Stefan

2014-10-01

A systematic approach to the direct numerical simulation (DNS) of breaking upper mesospheric inertia-gravity waves of amplitude close to or above the threshold for static instability is presented. Normal mode or singular vector analysis applied in a frame of reference moving with the phase velocity of the wave (in which the wave is a steady solution) is used to determine the most likely scale and structure of the primary instability and to initialize nonlinear "2.5-D" simulations (with three-dimensional velocity and vorticity fields but depending only on two spatial coordinates). Singular vector analysis is then applied to the time-dependent 2.5-D solution to predict the transition of the breaking event to three-dimensional turbulence and to initialize three-dimensional DNS. The careful choice of the computational domain and the relatively low Reynolds numbers, on the order of 25,000, relevant to breaking waves in the upper mesosphere, makes the three-dimensional DNS tractable with present-day computing clusters. Three test cases are presented: a statically unstable low-frequency inertia-gravity wave, a statically and dynamically stable inertia-gravity wave, and a statically unstable high-frequency gravity wave. The three-dimensional DNS are compared to ensembles of 2.5-D simulations. In general, the decay of the wave and generation of turbulence is faster in three dimensions, but the results are otherwise qualitatively and quantitatively similar, suggesting that results of 2.5-D simulations are meaningful if the domain and initial condition are chosen properly.

Mesospheric Precursors to the Major Stratospheric Sudden Warming of 2009: Validation and Dynamical Attribution using a Ground-to-Edge-of-Space Data Assimilation System

DTIC Science & Technology

2011-01-01

et al., 2008). Since wind observations are sparse and standard data assimilation systems ( DASs ) do not extend through the mesosphere, we have far...et al., 2008). Figure 1f plots a time-height cross section of wave- 2 F z at 60◦N, scaled by exp(z/2H), where z is pres- sure altitude and H =7 km. As

Seasonal Transport in Mars' Mesosphere revealed by Nitric Oxide Nightglow vertical profiles and global images from IUVS/MAVEN

NASA Astrophysics Data System (ADS)

Stiepen, Arnaud; Stewart, Ian; Jain, Sonal; Schneider, Nicholas; Deighan, Justin; Gonzàlez-Galindo, Francisco; Gérard, Jean-Claude; Stevens, Michael; Bougher, Stephen; Milby, Zachariah; Evans, Scott; Chaffin, Michael; McClintock, William; Clarke, John; Holsclaw, Greg; Montmessin, Franck; Lefèvre, Franck; Lo, Daniel; Jakosky, Bruce

2017-04-01

We analyze the ultraviolet nightglow in the atmosphere of Mars through Nitric Oxide (NO) δ and γ bands emissions. On the dayside thermosphere of Mars, solar extreme ultraviolet radiation partly dissociates CO2 and N2 molecules. O(3P) and N(4S) atoms are carried by the day-to-night hemispheric transport. They preferentially descend in the nightside mesosphere in the winter hemisphere, where they can radiatively recombine to form NO(C2Π). The excited molecules promptly relax by emitting photons in the UV δ bands and in the γ bands through cascades via the A2Σ, v' = 0 state. These emissions are thus indicators of the N and O atom fluxes transported from the dayside to Mars' nightside and the winter descending circulation pattern from the nightside thermosphere to the mesosphere (e.g. Bertaux et al., 2005 ; Bougher et al., 1990 ; Cox et al., 2008 ; Gagné et al., 2013 ; Gérard et al., 2008 ; Stiepen et al., 2015). Observations of these emissions have been accumulated on a large dataset of nightside disk images and vertical profiles obtained at the limb by the Imaging Ultraviolet Spectrograph (IUVS, McClintock et al., 2015) instrument when the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft is at its apoapsis and its periapsis phases along its orbit, respectively. We present discussion on the variability in the brightness, altitude and topside scale height of the emission with season, geographical position and local time and possible interpretation for local and global changes in the mesosphere dynamics. IUVS images and limb scans reveal unexpected complex structure of the emission. The brightest emission is observed close to the winter pole. The emission is also surprisingly more intense in some sectors located close to the equator : at 120˚ and 150˚ longitude. Observations also reveal spots and streaks, indicating irregularities in the wind circulation pattern and possible impact of waves and tides. The disk images and limb profiles are compared to

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.

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.

The third stage of the Orbital Sciences Pegasus XL rocket is bei

NASA Image and Video Library

2007-04-03

At Vandenberg Air Force Base in California, the Orbital Sciences Pegasus XL rocket is ready for mating to the AIM spacecraft. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. Launch from the Pegasus XL rocket is scheduled for April 25.

The third stage of the Orbital Sciences Pegasus XL rocket is bei

NASA Image and Video Library

2007-04-03

At Vandenberg Air Force Base in California, a technician mates the AIM spacecraft, at left, to the Orbital Sciences Pegasus XL rocket, at right. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. Launch from the Pegasus XL rocket is scheduled for April 25.

Fractionation and characterization of organic matter in wastewater from a swine waste-retention basin

USGS Publications Warehouse

Leenheer, Jerry A.; Rostad, Colleen E.

2004-01-01

Organic matter in wastewater sampled from a swine waste-retention basin in Iowa was fractionated into 14 fractions on the basis of size (particulate, colloid, and dissolved); volatility; polarity (hydrophobic, transphilic, hydrophilic); acid, base, neutral characteristics; and precipitate or flocculates (floc) formation upon acidification. The compound-class composition of each of these fractions was determined by infrared and 13C-NMR spectral analyses. Volatile acids were the largest fraction with acetic acid being the major component of this fraction. The second most abundant fraction was fine particulate organic matter that consisted of bacterial cells that were subfractionated into extractable lipids consisting of straight chain fatty acids, peptidoglycans components of bacterial cell walls, and protein globulin components of cellular plasma. The large lipid content of the particulate fraction indicates that non-polar contaminants, such as certain pharmaceuticals added to swine feed, likely associate with the particulate fraction through partitioning interactions. Hydrocinnamic acid is a major component of the hydrophobic acid fraction, and its presence is an indication of anaerobic degradation of lignin originally present in swine feed. This is the first study to combine particulate organic matter with dissolved organic matter fractionation into a total organic matter fractionation and characterization.

Representation of solar tides in the stratosphere and lower mesosphere in state-of-the-art reanalyses and in satellite observations

NASA Astrophysics Data System (ADS)

Sakazaki, Takatoshi; Fujiwara, Masatomo; Shiotani, Masato

2018-02-01

Atmospheric solar tides in the stratosphere and the lower mesosphere are investigated using temperature data from five state-of-the-art reanalysis data sets (MERRA-2, MERRA, JRA-55, ERA-Interim, and CFSR) as well as TIMED SABER and Aura MLS satellite measurements. The main focus is on the period 2006-2012 during which the satellite observations are available for direct comparison with the reanalyses. Diurnal migrating tides, semidiurnal migrating tides, and nonmigrating tides are diagnosed. Overall the reanalyses agree reasonably well with each other and with the satellite observations for both migrating and nonmigrating components, including their vertical structure and the seasonality. However, the agreement among reanalyses is more pronounced in the lower stratosphere and relatively weaker in the upper stratosphere and mesosphere. A systematic difference between SABER and the reanalyses is found for diurnal migrating tides in the upper stratosphere and the lower mesosphere; specifically, the amplitude of trapped modes in reanalyses is significantly smaller than that in SABER, although such difference is less clear between MLS and the reanalyses. The interannual variability and the possibility of long-term changes in migrating tides are also examined using the reanalyses during 1980-2012. All the reanalyses agree in exhibiting a clear quasi-biennial oscillation (QBO) in the tides, but the most significant indications of long-term changes in the tides represented in the reanalyses are most plausibly explained by the evolution of the satellite observing systems during this period. The tides are also compared in the full reanalyses produced by the Japan Meteorological Agency (i.e., JRA-55) and in two parallel data sets from this agency: one (JRA-55C) that repeats the reanalysis procedure but without any satellite data assimilated and one (JRA-55AMIP) that is a free-running integration of the model constrained only by observed sea surface temperatures. Many aspects

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.

Mesospheric gravity wave momentum flux estimation using hybrid Doppler interferometry

NASA Astrophysics Data System (ADS)

Spargo, Andrew J.; Reid, Iain M.; MacKinnon, Andrew D.; Holdsworth, David A.

2017-06-01

Mesospheric gravity wave (GW) momentum flux estimates using data from multibeam Buckland Park MF radar (34.6° S, 138.5° E) experiments (conducted from July 1997 to June 1998) are presented. On transmission, five Doppler beams were symmetrically steered about the zenith (one zenith beam and four off-zenith beams in the cardinal directions). The received beams were analysed with hybrid Doppler interferometry (HDI) (Holdsworth and Reid, 1998), principally to determine the radial velocities of the effective scattering centres illuminated by the radar. The methodology of Thorsen et al. (1997), later re-introduced by Hocking (2005) and since extensively applied to meteor radar returns, was used to estimate components of Reynolds stress due to propagating GWs and/or turbulence in the radar resolution volume. Physically reasonable momentum flux estimates are derived from the Reynolds stress components, which are also verified using a simple radar model incorporating GW-induced wind perturbations. On the basis of these results, we recommend the intercomparison of momentum flux estimates between co-located meteor radars and vertical-beam interferometric MF radars. It is envisaged that such intercomparisons will assist with the clarification of recent concerns (e.g. Vincent et al., 2010) of the accuracy of the meteor radar technique.

Tracer evolution in winds generated by a global spectral mechanistic model

NASA Technical Reports Server (NTRS)

Nielsen, J. E.; Rood, Richard B.; Couglass, Anne R.; Cerniglia, Mark C.; Allen, Dale J.; Rosenfield, Joan E.

1994-01-01

The lower boundary of a spectral mechanistic model is prescribed with 100 hPa geopotentials, and its performance during a November 1989 through March 1990 integration is compared with National Meteorological Center observations. Although the stratopause temperatures quickly become biased near the pole in both hemispheres, the model develops a residual mean circulation which shows significant descent over the winter pole and ascent in the tropics and over the summer pole at pressures less than 10 hPa. The daily correspondence of observed to modeled features in the upper stratosphere and mesosphere degrades after one month. However, the long-term variability qualitatively follows the observations. The results of off-line transport experiments are also described. A passive tracer is instantaneously injected into the flow over the poles and evolves in a manner which is consistent with the residual mean circulation. It demonstrates a significant cross-equatorial flux in the mesosphere near solstice, and air which originates in the southern hemisphere polar mesosphere can be found descending deep into the nothern polar stratosphere at the end of the integration. Nitrous oxide is also transported, and its ability to act as a dynamical tracer is evaluated by comparison to the evolution of the passive tracer.

Airborne Polarized Lidar Detection of Scattering Layers in the Ocean

NASA Astrophysics Data System (ADS)

Vasilkov, Alexander P.; Goldin, Yury A.; Gureev, Boris A.; Hoge, Frank E.; Swift, Robert N.; Wright, C. Wayne

2001-08-01

A polarized lidar technique based on measurements of waveforms of the two orthogonal-polarized components of the backscattered light pulse is proposed to retrieve vertical profiles of the seawater scattering coefficient. The physical rationale for the polarized technique is that depolarization of backscattered light originating from a linearly polarized laser beam is caused largely by multiple small-angle scattering from particulate matter in seawater. The magnitude of the small-angle scattering is determined by the scattering coefficient. Therefore information on the vertical distribution of the scattering coefficient can be derived potentially from measurements of the timedepth dependence of depolarization in the backscattered laser pulse. The polarized technique was verified by field measurements conducted in the Middle Atlantic Bight of the western North Atlantic Ocean that were supported by in situ measurements of the beam attenuation coefficient. The airborne polarized lidar measured the timedepth dependence of the backscattered laser pulse in two orthogonal-polarized components. Vertical profiles of the scattering coefficient retrieved from the timedepth depolarization of the backscattered laser pulse were compared with measured profiles of the beam attenuation coefficient. The comparison showed that retrieved profiles of the scattering coefficient clearly reproduce the main features of the measured profiles of the beam attenuation coefficient. Underwater scattering layers were detected at depths of 2025 m in turbid coastal waters. The improvement in dynamic range afforded by the polarized lidar technique offers a strong potential benefit for airborne lidar bathymetric applications.

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.

Formation and occurrence of new polar iodinated disinfection byproducts in drinking water.

PubMed

Pan, Yang; Li, Wenbin; An, Hao; Cui, Hao; Wang, Ying

2016-02-01

During drinking water disinfection, iodinated disinfection byproducts (I-DBPs) can be generated through reactions between iodide, disinfectants, and natural organic matter. Drinking water I-DBPs have been increasingly attracting attention as emerging organic pollutants as a result of their significantly higher toxicity and growth inhibition than their chloro- and bromo-analogues. In this study, by adopting ultra performance liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry precursor ion scan, multiple reaction monitoring, and product ion scan analyses, 11 new polar I-DBPs with confirmed structures and eight new polar I-DBPs with proposed structures were detected in simulated drinking water samples. Chloramination of simulated raw waters containing natural organic matter with higher aromaticity produced higher levels of new phenolic I-DBPs. Formation of new polar I-DBPs and total organic iodine (TOI) was most favored in chloramination, followed by chlorine dioxide treatment, and relatively minor in chlorination. Lower pH in chloramination substantially enhanced the formation of new polar I-DBPs and TOI. NH2Cl and dissolved organic nitrogen could be important nitrogen sources and precursors for formation of the two new nitrogenous phenolic I-DBPs. Notably, in tap water samples collected from nine major cities located in the Yangtze River Delta region of China, seven of the 11 new polar I-DBPs with confirmed structures were detected at levels from 0.11 to 28 ng/L, and the two new nitrogenous phenolic I-DBPs were ubiquitous with concentrations from 0.12 to 24 ng/L, likely due to the relatively high dissolved organic nitrogen levels in regional source waters. Copyright © 2015 Elsevier Ltd. All rights reserved.

TIME after TIMED - A perspective on Thermosphere-Ionosphere Mesosphere science and future observational needs after the TIMED mission epoch

NASA Astrophysics Data System (ADS)

Mlynczak, M. G.; Russell, J. M., III; Hunt, L. A.; Christensen, A. B.; Paxton, L. J.; Woods, T. N.; Niciejewski, R.; Yee, J. H.

2016-12-01

The past 40 years have been a true golden age for space-based observations of the Earth's middle atmosphere (stratosphere to thermosphere). Numerous instruments and missions have been developed and flown to explore the thermal structure, chemical composition, and energy budget of the middle atmosphere. A primary motivation for these observations was the need to understand the photochemistry of stratospheric ozone and its potential depletion by anthropogenic means. As technology evolved, observations were extended higher and higher, into regions previously unobserved from space by optical remote sensing techniques. In the 1990's, NASA initiated the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamcis (TIMED) mission to explore one of the last frontiers of the atmosphere - the region between 60 and 180 km - then referred to as "the ignorosphere." Today, we have 15 years of detailed observations from this remarkable satellite and its 4 instruments, and are recognizing rapid climate change that is occurring above 60 km. The upcoming ICON and GOLD missions will afford new opportunities for scientific discovery by combining data from all three missions. However, it has become clear that continued observations beyond TIMED are required to understand the upper atmosphere as a system that is fully coupled from the edge of Space to the surface of the Earth. In this talk we will review the current status of knowledge of the basic state properties of the thermosphere-ionosphere-mesosphere (TIME) system and will discuss future observations that are required to obtain a comprehensive understanding of the entire TIME system, especially the effects of long term change that are already underway.

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.

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.

Solar Cycle Response and Long-Term Trends in the Mesospheric Metal Layers

NASA Technical Reports Server (NTRS)

Dawkins, E. C. M.; Plane, J. M. C.; Chipperfield, M.; Feng, W.; Marsh, D. R.; Hoffner, J.; Janches, D.

2016-01-01

The meteoric metal layers (Na, Fe, and K) 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. In this work, we examine whether these metal layers are sensitive Fe indicators of decadal long-term changes within the upper atmosphere. Output from a whole-atmosphere climate model is used to assess the response of the Na, K, and Fe layers across a 50 year period (1955-2005). At short timescales, the K layer has previously been shown to exhibit a very different seasonal behavior compared to the other metals. Here we show that this unusual behavior is also exhibited at longer time scales (both the 11 year solar cycle and 50 year periods), where K displays a much more pronounced response to atmospheric temperature changes than either Na or Fe. The contrasting solar cycle behavior of the K and Na layers predicted by the model is confirmed using satellite and lidar observations for the period 2004-2013.

Inter-annual and Long-term Temperature Variations in the Mesopause Region at High Latitudes Generated by the Stratospheric QBO

NASA Technical Reports Server (NTRS)

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

2007-01-01

The Numerical Spectral Model (NSM) simulates the Quasi-biennial Oscillation (QBO) that dominates the zonal circulation of the lower stratosphere at low latitudes. In the model, the QBO is generated with parameterized small-scale gravity waves (GW), which are partially augmented in 3D with planetary waves owing to baroclinic instability. Due to GW filtering, the QBO extends into the upper mesosphere, evident in UARS zonal wind and TIMED temperature measurements. While the QBO zonal winds are confined to equatorial latitudes, even in simulations with latitude-independent wave source, the associated temperature variations extend to high latitudes. The meridional circulation redistributes some of the QBO energy to focus it partially onto the Polar Regions. The resulting QBO temperature variations away from the equator tend to increase at higher altitudes to produce inter-annual variations that can exceed 5 K in the polar mesopause region -- and our 3D model simulations show that the effect is variable from year to year and can produce large differences between the two hemispheres, presumably due to interactions involving the seasonal variations. Modeling studies with the NSM have shown that long-term variations can also be generated by the QBO interacting with the seasonal cycles through OW node-filtering. A 30-month QBO, optimally synchronized by the 6-month Semi-Annual Oscillation (SAO), thus produces a 5-year or semi-decadal (SD) oscillation -- and observational evidence for that has been provided by a recent analysis of stratospheric NCEP data. In a simulation with the 2D version of the NSM, this SD oscillation extends into the upper mesosphere, and we present results to show that the related temperature variations could contribute significantly to the long-term variations of the polar mesopause region. Quasi-decadal variations could furthermore arise from the modeled solar cycle modulations of the QBO and 12-month annual oscillation. Our numerical results are

Observation of macroscopic valley-polarized monolayer exciton-polaritons at room temperature

NASA Astrophysics Data System (ADS)

Lundt, N.; Stoll, S.; Nagler, P.; Nalitov, A.; Klembt, S.; Betzold, S.; Goddard, J.; Frieling, E.; Kavokin, A. V.; Schüller, C.; Korn, T.; Höfling, S.; Schneider, C.

2017-12-01

In this Rapid Communication, we address the chiral properties of valley exciton-polaritons in a monolayer of W S2 in the regime of strong light-matter coupling with a Tamm-plasmon resonance. We observe that the effect of valley polarization, which manifests in the circular polarization of the emitted photoluminescence as the sample is driven by a circularly polarized laser, is strongly enhanced in comparison to bare W S2 monolayers and can even be observed under strongly nonresonant excitation at ambient conditions. In order to explain this effect in more detail, we study the relaxation and decay dynamics of exciton-polaritons in our device, elaborate the role of the dark state, and present a microscopic model to explain the wave-vector-dependent valley depolarization by the linear polarization splitting inherent to the microcavity. We believe that our findings are crucial for designing novel polariton-valleytronic devices which can be operated at room temperature.

Earth-from-Luna Limb Imager (ELLI) for Deep Space Gateway

NASA Astrophysics Data System (ADS)

Gorkavyi, N.; DeLand, M.

2018-02-01

The new type of limb imager with a high-frequency imaging proposed for Deep Space Gateway. Each day this CubeSat' scale imager will generate the global 3D model of the aerosol component of the Earth's atmosphere and Polar Mesospheric Clouds.

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.

The Case Against Charge Transfer Interactions in Dissolved Organic Matter Photophysics.

PubMed

McKay, Garrett; Korak, Julie A; Erickson, Paul R; Latch, Douglas E; McNeill, Kristopher; Rosario-Ortiz, Fernando L

2018-01-16

The optical properties of dissolved organic matter influence chemical and biological processes in all aquatic ecosystems. Dissolved organic matter optical properties have been attributed to a charge-transfer model in which donor-acceptor complexes play a primary role. This model was evaluated by measuring the absorbance and fluorescence response of organic matter isolates to changes in solvent temperature, viscosity, and polarity, which affect the position and intensity of spectra for known donor-acceptor complexes of organic molecules. Absorbance and fluorescence spectral shape were largely unaffected by these changes, indicating that the distribution of absorbing and emitting species was unchanged. Overall, these results call into question the wide applicability of the charge-transfer model for explaining organic matter optical properties and suggest that future research should explore other models for dissolved organic matter photophysics.

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.

Illuminating the Background: Topics in Cosmic Microwave Background Polarization Research

NASA Astrophysics Data System (ADS)

Miller, Nathan J.

The cosmic microwave background provides a wealth of information about the origin and history of the universe. The statistics of the anisotropy and the polarization of the cosmic microwave background, among other things, can tell us about the distribution of matter, the redshift of reionization, and the nature of the primordial uctuations. From the lensing of cosmic microwave background due to intervening matter, we can extract information about neutrinos and the equation of state of dark energy. A measurement of the large angular scale B-mode polarization has been called the "smoking gun" of in ation, a theory that describes a possible early rapid expansion of the universe. The focus of current experiments is to measure this B-mode polarization, while several experiments, such as POLARBEAR, are also looking to measure the lensing of the cosmic microwave background. This dissertation will discuss several different topics in cosmic microwave background polarization research. I will make predictions for future experiments and I will also show analysis for two current experiments, POLARBEAR and BICEP. I will show how beam systematics affect the measurement of cosmological parameters and how well we must limit these systematics in order to get unbiased constraints on cosmological parameters for future experiments. I will discuss a novel way of using the temperature-polarization cross correlation to constrain the amount of inflationary gravitational waves. Through Markov Chain Monte Carlo methods, I will determine how well future experiments will be able to constrain the neutrino masses and their degeneracy parameters. I will show results from current data analysis and calibration being done on the Cedar Flat deployment for the POLARBEAR experiment which is currently being constructed in the Atacama desert in Chile. Finally, I will analyze the claim of detection of cosmological birefringence in the BICEP data and show that there is reason to believe it is due to

Spatio-temporal observations of tertiary ozone maximum

NASA Astrophysics Data System (ADS)

Sofieva, V. F.; Kyrölä, E.; Verronen, P. T.; Seppälä, A.; Tamminen, J.; Marsh, D. R.; Smith, A. K.; Bertaux, J.-L.; Hauchecorne, A.; Dalaudier, F.; Fussen, D.; Vanhellemont, F.; Fanton D'Andon, O.; Barrot, G.; Guirlet, M.; Fehr, T.; Saavedra, L.

2009-03-01

We present spatio-temporal distributions of tertiary ozone maximum (TOM), based on GOMOS (Global Ozone Monitoring by Occultation of Stars) ozone measurements in 2002-2006. The tertiary ozone maximum is typically observed in the high-latitude winter mesosphere at altitude ~72 km. Although the explanation for this phenomenon has been found recently - low concentrations of odd-hydrogen cause the subsequent decrease in odd-oxygen losses - models have had significant deviations from existing observations until recently. Good coverage of polar night regions by GOMOS data has allowed for the first time obtaining spatial and temporal observational distributions of night-time ozone mixing ratio in the mesosphere. The distributions obtained from GOMOS data have specific features, which are variable from year to year. In particular, due to a long lifetime of ozone in polar night conditions, the downward transport of polar air by the meridional circulation is clearly observed in the tertiary ozone maximum time series. Although the maximum tertiary ozone mixing ratio is achieved close to the polar night terminator (as predicted by the theory), TOM can be observed also at very high latitudes, not only in the beginning and at the end, but also in the middle of winter. We have compared the observational spatio-temporal distributions of tertiary ozone maximum with that obtained using WACCM (Whole Atmosphere Community Climate Model) and found that the specific features are reproduced satisfactorily by the model. Since ozone in the mesosphere is very sensitive to HOx concentrations, energetic particle precipitation can significantly modify the shape of the ozone profiles. In particular, GOMOS observations have shown that the tertiary ozone maximum was temporarily destroyed during the January 2005 and December 2006 solar proton events as a result of the HOx enhancement from the increased ionization.

Spatio-temporal observations of the tertiary ozone maximum

NASA Astrophysics Data System (ADS)

Sofieva, V. F.; Kyrölä, E.; Verronen, P. T.; Seppälä, A.; Tamminen, J.; Marsh, D. R.; Smith, A. K.; Bertaux, J.-L.; Hauchecorne, A.; Dalaudier, F.; Fussen, D.; Vanhellemont, F.; Fanton D'Andon, O.; Barrot, G.; Guirlet, M.; Fehr, T.; Saavedra, L.

2009-07-01

We present spatio-temporal distributions of the tertiary ozone maximum (TOM), based on GOMOS (Global Ozone Monitoring by Occultation of Stars) ozone measurements in 2002-2006. The tertiary ozone maximum is typically observed in the high-latitude winter mesosphere at an altitude of ~72 km. Although the explanation for this phenomenon has been found recently - low concentrations of odd-hydrogen cause the subsequent decrease in odd-oxygen losses - models have had significant deviations from existing observations until recently. Good coverage of polar night regions by GOMOS data has allowed for the first time to obtain spatial and temporal observational distributions of night-time ozone mixing ratio in the mesosphere. The distributions obtained from GOMOS data have specific features, which are variable from year to year. In particular, due to a long lifetime of ozone in polar night conditions, the downward transport of polar air by the meridional circulation is clearly observed in the tertiary ozone maximum time series. Although the maximum tertiary ozone mixing ratio is achieved close to the polar night terminator (as predicted by the theory), TOM can be observed also at very high latitudes, not only in the beginning and at the end, but also in the middle of winter. We have compared the observational spatio-temporal distributions of the tertiary ozone maximum with that obtained using WACCM (Whole Atmosphere Community Climate Model) and found that the specific features are reproduced satisfactorily by the model. Since ozone in the mesosphere is very sensitive to HOx concentrations, energetic particle precipitation can significantly modify the shape of the ozone profiles. In particular, GOMOS observations have shown that the tertiary ozone maximum was temporarily destroyed during the January 2005 and December 2006 solar proton events as a result of the HOx enhancement from the increased ionization.

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

PubMed

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

2017-06-01

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

Ozone-Temperature Diurnal and Longer Term Correlations, in the Lower Thermosphere, Mesosphere and Stratosphere, Based on Measurements from SABER on TIMED

NASA Technical Reports Server (NTRS)

Huang, Frank T.; Mayr, Hans G.; Russell, James M., III; Mlynczak, Martin G.

2012-01-01

The analysis of mutual ozone-temperature variations can provide useful information on their interdependencies relative to the photochemistry and dynamics governing their behavior. Previous studies have mostly been based on satellite measurements taken at a fixed local time in the stratosphere and lower mesosphere. For these data, it is shown that the zonal mean ozone amounts and temperatures in the lower stratosphere are mostly positively correlated, while they are mostly negatively correlated in the upper stratosphere and in the lower mesosphere. The negative correlation, due to the dependence of photochemical reaction rates on temperature, indicates that ozone photochemistry is more important than dynamics in determining the ozone amounts. In this study, we provide new results by extending the analysis to include diurnal variations over 24 hrs of local time, and to larger spatial regimes, to include the upper mesosphere and lower thermosphere (MLT). The results are based on measurements by the SABER instrument on the TIMED satellite. For mean variations (i.e., averages over local time and longitude) in the MLT, our results show that there is a sharp reversal in the correlation near 80 km altitude, above which the ozone mixing ratio and temperature are mostly positively correlated, while they are mostly negatively correlated below 80 km. This is consistent with the view that above -80 km, effects due to dynamics are more important compared to photochemistry. For diurnal variations, both the ozone and temperature show phase progressions in local time, as a function of altitude and latitude. For temperature, the phase progression is as expected, as they represent migrating tides. For day time ozone, we also find regular phase progression in local time over the whole altitude range of our analysis, 25 to 105 km, at least for low latitudes. This was not previously known, although phase progressions had been noted by us and by others at lower altitudes. For diurnal

The third stage of the Orbital Sciences Pegasus XL rocket is bei

NASA Image and Video Library

2007-04-03

At Vandenberg Air Force Base in California, the third stage of the Orbital Sciences Pegasus XL rocket is being mated to the AIM spacecraft, at right. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. Launch from the Pegasus XL rocket is scheduled for April 25.

The mated Pegasus XL rocket - AIM spacecraft leaves Building 165

NASA Image and Video Library

2007-04-16

The mated Pegasus XL rocket - AIM spacecraft is secured onto a transporter at Vandenberg Air Force Base in California. The rocket will be transferred to a waiting Orbital Sciences Stargazer L-1011 aircraft for launch. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. Launch is scheduled for April 25.

KSC-07pd0993

NASA Image and Video Library

2007-04-04

KENNEDY SPACE CENTER, FLA. -- At Vandenberg Air Force Base in California, a technician mates the AIM spacecraft, at left, to the Orbital Sciences Pegasus XL rocket, at right. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. Launch from the Pegasus XL rocket is scheduled for April 25.

KSC-07pd0991

NASA Image and Video Library

2007-04-03

KENNEDY SPACE CENTER, FLA. -- At Vandenberg Air Force Base in California, the third stage of the Orbital Sciences Pegasus XL rocket is being mated to the AIM spacecraft, at right. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. Launch from the Pegasus XL rocket is scheduled for April 25.

The mated Pegasus XL rocket - AIM spacecraft leaves Building 165

NASA Image and Video Library

2007-04-16

The mated Pegasus XL rocket - AIM spacecraft leaves Building 1655 at Vandenberg Air Force Base in California. The rocket will be transferred to a waiting Orbital Sciences Stargazer L-1011 aircraft for launch. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. Launch is scheduled for April 25.

Quantum storage of a photonic polarization qubit in a solid.

PubMed

Gündoğan, Mustafa; Ledingham, Patrick M; Almasi, Attaallah; Cristiani, Matteo; de Riedmatten, Hugues

2012-05-11

We report on the quantum storage and retrieval of photonic polarization quantum bits onto and out of a solid state storage device. The qubits are implemented with weak coherent states at the single photon level, and are stored for a predetermined time of 500 ns in a praseodymium doped crystal with a storage and retrieval efficiency of 10%, using the atomic frequency comb scheme. We characterize the storage by using quantum state tomography, and find that the average conditional fidelity of the retrieved qubits exceeds 95% for a mean photon number μ=0.4. This is significantly higher than a classical benchmark, taking into account the poissonian statistics and finite memory efficiency, which proves that our crystal functions as a quantum storage device for polarization qubits. These results extend the storage capabilities of solid state quantum light matter interfaces to polarization encoding, which is widely used in quantum information science.

Condition of The Stratospheric and Mesospheric Ozone Layer Over Bulgaria for the Period 1996-2012

NASA Astrophysics Data System (ADS)

Kaleyna, Petya; Mukhtarov, Plamen; Miloshev, Nikolay

2014-05-01

A detailed analysis of the variations of the stratospheric and mesospheric ozone over Bulgaria, in the period 1996-2012, is presented in the article on the basis of ground and satellite measurements of the Total Ozone Content (TOC). The move of the most important components: yearly running mean values, amplitudes and phases of the first four harmonics of the seasonal cycle. Their mean values for the period and the existing long term trends have been found. An evaluation of the general characteristics of the short term variability of the Total Ozone Content (TOC) over Bulgaria also has been made in the article. The impact of the planetary wave activity of the stratosphere on the total ozone has been studied and the climatology of the oscillation amplitudes with periods of 4, 7, 11 and 25 days has been defined.

Temporal Variations of Titan's Middle-Atmospheric Temperatures From 2004-2009 Observed by Cassini/CIRS

NASA Technical Reports Server (NTRS)

Achterberg, Richard K.; Gierasch, Peter J.; Flasar, F. Michael; Nixon, Conor A.

2010-01-01

We use five and one-half years of limb- and nadir-viewing temperature mapping observations by the Composite Infrared Radiometer-Spectrometer (CIRS) on the Cassini Saturn orbiter, taken between July 2004 and December 2009 (Ls from 293deg to 4deg; northern mid-winter to just after northern spring equinox), to monitor temperature changes in the upper stratosphere and lower mesosphere of Titan. The largest changes are in the northern (winter) polar stratopause, which has declined in temperature by over 20 K between 2005 and 2009. Throughout the rest of the mid to upper stratosphere and lower mesosphere, temperature changes are less than 5 K. In the southern hemisphere, temperatures in the middle stratosphere near 1 mbar increased by 1 to 2K from 2004 through early 2007, then declined by 2 to 4K throughout 2008 and 2009, with the changes, being larger at more, polar latitudes. Middle stratospheric temperatures at mid-northern latitudes show a small 1 to 2K increase, from 2005 through 2009. At north polar latitudes within the polar vortex, temperatures in the middle stratosphe=re show a approx. 4 K increase during 2007, followed by a comparable decrease in temperatures in 2008 and into early 2009. The observed temperature. changes in the north polar region are consistent with a weakening of the subsidence within the descending branch of the middle atmosphere meridional circulation.

Temporal Variations of Titan's Middle-Atmospheric Temperatures from 2004 to 2009 Observed by Cassini/CIRS

NASA Technical Reports Server (NTRS)

Achterberg, Richard K.; Gierasch, Peter J.; Conrath, Barney J.; Flasar, F. Michael; Nixon, Conor A.

2011-01-01

We use five and one-half years of limb- and nadir-viewing temperature mapping observations by the Composite Infrared Radiometer-Spectrometer (CIRS) on the Cassini Saturn orbiter, taken between July 2004 and December 2009 (Ls from 293 deg. to 48 deg.; northern mid-winter to just after northern spring equinox), to monitor temperature changes in the upper stratosphere and lower mesosphere of Titan. The largest changes are in the northern (winter) polar stratopause, which has declined in temperature by over 20 K between 2005 and 2009. Throughout the rest of the mid to upper stratosphere and lower mesosphere, temperature changes are less than 5 K. In the southern hemisphere, temperatures in the middle stratosphere near 1 mbar increased by 1-2 K from 2004 through early 2007, then declined by 2-4 K throughout 2008 and 2009, with the changes being larger at more polar latitudes. Middle stratospheric temperatures at mid-northern latitudes show a small 1-2 K increase from 2005 through 2009, at north polar latitudes within the polar vortex, temperatures in the middle stratosphere show an approximately 4 K increase during 2007, followed by a comparable decrease in temperatures in 2008 and into early 2009. The observed temperature changes in the north polar region are consistent with a weakening of the subsidence within the descending branch of the middle atmosphere meridional circulation.

On inter-hemispheric coupling in the middle atmosphere

NASA Astrophysics Data System (ADS)

Karlsson, Bodil; Bailey, S.; Benze, S.; Gumbel, J.; Harvey, V. L.; Kürnich, H.; Lossow, S.; McLandress, D. Marsh, C.; Merkel, A. W.; Mills, M.; Randall, C. E.; Russell, J.; Shepherd, T. G.

On inter-hemispheric coupling in the middle atmosphere From recent studies it is evident that planetary wave activity in the winter hemisphere influences the high-latitude summer mesosphere on the opposite side of the globe. This is an extraordinary example of multi-scale wave-mean flow interaction. The first indication of this inter-hemispheric coupling came from a model study by Becker and Schmitz (2003). Since then, the results have been reproduced in several models, and observations have confirmed the existence of this link. We present current understanding of inter-hemispheric coupling and its consequences for the middle atmosphere, focusing on the summer mesosphere where polar mesospheric clouds (PMCs) form. The results shown are based on year-to-year and intra-seasonal variability in PMCs ob-served by the Odin satellite and the Aeronomy of Ice in the Mesosphere (AIM) satellite, as well as on model results from the extended Canadian Middle Atmosphere Model (CMAM), the Whole Atmosphere Community Climate Model (WACCM) and the Kühlungsborn Mechanis-u tic general Circulation Model (KMCM). The latter has been used to pinpoint the proposed mechanism behind the inter-hemispheric coupling.

Seasonal variability of atmospheric tides in the mesosphere and lower thermosphere: meteor radar data and simulations

NASA Astrophysics Data System (ADS)

Pokhotelov, Dimitry; Becker, Erich; Stober, Gunter; Chau, Jorge L.

2018-06-01

Thermal tides play an important role in the global atmospheric dynamics and provide a key mechanism for the forcing of thermosphere-ionosphere dynamics from below. A method for extracting tidal contributions, based on the adaptive filtering, is applied to analyse multi-year observations of mesospheric winds from ground-based meteor radars located in northern Germany and Norway. The observed seasonal variability of tides is compared to simulations with the Kühlungsborn Mechanistic Circulation Model (KMCM). It is demonstrated that the model provides reasonable representation of the tidal amplitudes, though substantial differences from observations are also noticed. The limitations of applying a conventionally coarse-resolution model in combination with parametrisation of gravity waves are discussed. The work is aimed towards the development of an ionospheric model driven by the dynamics of the KMCM.

Periodic variations in stratospheric-mesospheric temperature from 20-65 km at 80 N to 30 S

NASA Technical Reports Server (NTRS)

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

1975-01-01

Results on large-scale periodic variations of the stratospheric-mesospheric temperature field based on Meteorological Rocket Network (MRN) measurements are reported for a long-term (12-year) mean, the quasi-biennial oscillation (QBO), and the first three harmonics of the annual wave (annual wave, semi-annual wave, and terannual wave or 4-month variation). Station-to-station comparisons are tabulated and charted for amplitude and phase of periodic variations in the temperature field. Masking and biasing factors, such as diurnal tides, solar radiation variations, mean monthly variations, instrument lag, aerodynamic heating, are singled out for attention. Models of the stratosphere will have to account for these oscillations of different periods in the thermal field and related properties of the wind fields, with multilayered horizontal stratification with height taken into account.-

Estimates of the Size Distribution of Meteoric Smoke Particles From Rocket-Borne Impact Probes

NASA Astrophysics Data System (ADS)

Antonsen, Tarjei; Havnes, Ove; Mann, Ingrid

2017-11-01

Ice particles populating noctilucent clouds and being responsible for polar mesospheric summer echoes exist around the mesopause in the altitude range from 80 to 90 km during polar summer. The particles are observed when temperatures around the mesopause reach a minimum, and it is presumed that they consist of water ice with inclusions of smaller mesospheric smoke particles (MSPs). This work provides estimates of the mean size distribution of MSPs through analysis of collision fragments of the ice particles populating the mesospheric dust layers. We have analyzed data from two triplets of mechanically identical rocket probes, MUltiple Dust Detector (MUDD), which are Faraday bucket detectors with impact grids that partly fragments incoming ice particles. The MUDD probes were launched from Andøya Space Center (69°17'N, 16°1'E) on two payloads during the MAXIDUSTY campaign on 30 June and 8 July 2016, respectively. Our analysis shows that it is unlikely that ice particles produce significant current to the detector, and that MSPs dominate the recorded current. The size distributions obtained from these currents, which reflect the MSP sizes, are described by inverse power laws with exponents of k˜ [3.3 ± 0.7, 3.7 ± 0.5] and k˜ [3.6 ± 0.8, 4.4 ± 0.3] for the respective flights. We derived two k values for each flight depending on whether the charging probability is proportional to area or volume of fragments. We also confirm that MSPs are probably abundant inside mesospheric ice particles larger than a few nanometers, and the volume filling factor can be a few percent for reasonable assumptions of particle properties.

A new numerical model of the middle atmosphere. 2: Ozone and related species

NASA Technical Reports Server (NTRS)

Garcia, Rolando R.; Solomon, Susan

1994-01-01

A new two-dimensional model with detailed photochemistry is presented. The model includes descriptions of planetary wave and gravity wave propagation and dissipation to characterize the wave forcing and associated mixing in the stratosphere and mesosphere. Such a representation allows for explicit calculation of the regions of strong mixing in the middle atmosphere required for accurate simulation of trace gas transport. The new model also includes a detailed description of photochemical processes in the stratosphere and mesosphere. The downward transport of H2, H2O, and NO(y) from the mesosphere to the stratosphere is examined, and it is shown that mesospheric processes can influence the distributions of these chemical species in polar regions. For HNO3 we also find that small concentrations of liquid aerosols above 30 km could play a major role in determining the abundance in polar winter at high latitudes. The model is also used to examine the chemical budget of ozone in the midlatitude stratosphere and to set constraints on the effectiveness of bromine relative to chlorine for ozone loss and the role of the HO2 + BrO reaction. Recent laboratory data used in this modeling study suggest that this process greatly enhances the effectiveness of bromine for ozone destruction, making bromine-catalyzed chemistry second only to HO(x)-catalyzed ozone destruction in the contemporary stratosphere at midlatitudes below about 18 km. The calculated vertical distribution of ozone in the lower stratosphere agrees well with observations, as does the total column ozone during most seasons and latitudes, with the important exception of southern hemisphere winter and spring.

Mesopause Jumps: Observations and Explanation

NASA Astrophysics Data System (ADS)

Luebken, F. J.; Becker, E.; Höffner, J.; Viehl, T. P.; Latteck, R.

2017-12-01

Recent high resolution temperature measurements by resonance lidar at Davis (69°S) occasionally showed a sudden mesopause altitude increase by 5km and an associated mesopause temperature decrease by 10K. We present further observations which are closely related to this `mesopause jump', namely the increase of mean height of polar mesospheric summer echoes (PMSE) observed by a VHF radar, very strong westward winds in the upper mesosphere measured by an MF radar, and relatively large eastward winds in the stratosphere taken from reanalysis. We compare to similar observations in the Northern Hemisphere, namely at ALOMAR (69°N) where such mesopause jumps have never been observed. We present a detailed explanation of mesopause jumps. They occur only when stratospheric winds are moderately eastward and mesospheric winds are very large (westward). Under these conditions, gravity waves with comparatively large eastward phase speeds can pass the stratosphere and propagate to the lower thermosphere because their vertical wavelengths in the mesosphere are rather large which implies reduced dynamical stability. When finally breaking in the lower thermosphere, these waves drive an enhanced residual circulation that causes a cold and high-altitude mesopause. The conditions for a mesopause jump occur only in the Southern Hemisphere (SH) and are associated with the late breakdown of the polar vortex.Mesopause jumps are primarily, but not only, observed prior and close to solstice. We also show that during the onset of PMSE in the SH, stratospheric zonal winds are still eastward (up to 30m/s), and that the onset is not closely related to the transition of the stratospheric circulation.

Amplification and polarization of supernovae by gravitational lensing

NASA Technical Reports Server (NTRS)

Schneider, P.; Wagoner, Robert V.

1987-01-01

The gravitational lensing of supernovae by individual masses which could comprise the dark matter is analyzed. Detailed predictions of the amplification and polarization are presented, including effects of a galactic environment. Their time dependence is produced by the expansion of the supernovae beam within the lens. The fraction of supernovae which might thus be identified as being lensed in surveys at proposed limiting magnitudes is estimated. These two effects could provide the only known unique signature of microlensing.

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.

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.

Nonlocal thermodynamic equilibrium processes in ozone - Implications for the energy budget of the mesosphere and lower thermosphere

NASA Technical Reports Server (NTRS)

Milynczak, Martin G.

1991-01-01

The conversion of chemical potential energy and infrared radiative energy to kinetic energy by non-LTE processes involving ozone is a potentially significant source of heat in the terrestrial upper mesosphere and lower thermosphere. Heating rates are calculated and compared using two different statistical equilibrium models previously applied in the analysis of measurements of limb emission from ozone. The calculated heating depends strongly on the assumed distribution and relaxation of energy in the quasi-nascent ozone molecule. Finally, in the absence of a detailed data base of rate coefficients it may be possible to estimate the heating rate due to non-LTE processes in ozone from appropriate satellite measurements of the ozone concentration and of the infrared emission from ozone in the 9-12 micron spectral interval.

Rosiglitazone Promotes White Matter Integrity and Long-Term Functional Recovery After Focal Cerebral Ischemia.

PubMed

Han, Lijuan; Cai, Wei; Mao, Leilei; Liu, Jia; Li, Peiying; Leak, Rehana K; Xu, Yun; Hu, Xiaoming; Chen, Jun

2015-09-01

Oligodendrogenesis is essential for white matter repair after stroke. Although agonists of peroxisome proliferator-activated receptors γ confer neuroprotection in models of cerebral ischemia, it is not known whether this effect extends to white matter protection. This study tested the hypothesis that the peroxisome proliferator-activated receptors γ agonist rosiglitazone enhances oligodendrogenesis and improves long-term white matter integrity after ischemia/reperfusion. Male adult C57/BL6 mice (25-30 g) were subjected to 60-minute middle cerebral artery occlusion and reperfusion. Rosiglitazone (3 mg/kg) was injected intraperitoneally once daily for 14 days beginning 2 hours after reperfusion. Sensorimotor and cognitive functions were evaluated ≤21 days after middle cerebral artery occlusion. Immunostaining was used to assess infarct volume, myelin loss, and microglial activation. Bromodeoxyuridine (BrdU) was injected for measurements of proliferating NG2(+) oligodendrocyte precursor cells (OPCs) and newly generated adenomatous polyposis coli(+) oligodendrocytes. Mixed glial cultures were used to confirm the effect of rosiglitazone on oligodendrocyte differentiation and microglial polarization. Rosiglitazone significantly reduced brain tissue loss, ameliorated white matter injury, and improved sensorimotor and cognitive functions for at least 21 days after middle cerebral artery occlusion. Rosiglitazone enhanced OPC proliferation and increased the numbers of newly generated mature oligodendrocytes after middle cerebral artery occlusion. Rosiglitazone treatment also reduced the numbers of Iba1(+)/CD16(+) M1 microglia and increased the numbers of Iba1(+)/CD206(+) M2 microglia after stroke. Glial culture experiments confirmed that rosiglitazone promoted oligodendrocyte differentiation, perhaps by promoting microglial M2 polarization. Rosiglitazone treatment improves long-term white matter integrity after cerebral ischemia, at least, in part, by promoting

Emergent chirality in the electric polarization texture of titanate superlattices.

PubMed

Shafer, Padraic; García-Fernández, Pablo; Aguado-Puente, Pablo; Damodaran, Anoop R; Yadav, Ajay K; Nelson, Christopher T; Hsu, Shang-Lin; Wojdeł, Jacek C; Íñiguez, Jorge; Martin, Lane W; Arenholz, Elke; Junquera, Javier; Ramesh, Ramamoorthy

2018-01-30

Chirality is a geometrical property by which an object is not superimposable onto its mirror image, thereby imparting a handedness. Chirality determines many important properties in nature-from the strength of the weak interactions according to the electroweak theory in particle physics to the binding of enzymes with naturally occurring amino acids or sugars, reactions that are fundamental for life. In condensed matter physics, the prediction of topologically protected magnetic skyrmions and related spin textures in chiral magnets has stimulated significant research. If the magnetic dipoles were replaced by their electrical counterparts, then electrically controllable chiral devices could be designed. Complex oxide BaTiO 3 /SrTiO 3 nanocomposites and PbTiO 3 /SrTiO 3 superlattices are perfect candidates, since "polar vortices," in which a continuous rotation of ferroelectric polarization spontaneously forms, have been recently discovered. Using resonant soft X-ray diffraction, we report the observation of a strong circular dichroism from the interaction between circularly polarized light and the chiral electric polarization texture that emerges in PbTiO 3 /SrTiO 3 superlattices. This hallmark of chirality is explained by a helical rotation of electric polarization that second-principles simulations predict to reside within complex 3D polarization textures comprising ordered topological line defects. The handedness of the texture can be topologically characterized by the sign of the helicity number of the chiral line defects. This coupling between the optical and novel polar properties could be exploited to encode chiral signatures into photon or electron beams for information processing.

Numerical modeling of polar mesocyclones generation mechanisms

NASA Astrophysics Data System (ADS)

Sergeev, Dennis; Stepanenko, Victor

2013-04-01

Polar mesocyclones, commonly referred to as polar lows, remain of great interest due to their complicated dynamics. These mesoscale vortices are small short-living objects that are formed over the observation-sparse high-latitude oceans, and therefore, their evolution can hardly be observed and predicted numerically. The origin of polar mesoscale cyclones is still a matter of uncertainty, though the recent numerical investigations [3] have exposed a strong dependence of the polar mesocyclone development upon the magnitude of baroclinicity. Nevertheless, most of the previous studies focused on the individual polar low (the so-called case studies), with too many factors affecting it simultaneously. None of the earlier studies suggested a clear picture of polar mesocyclone generation within an idealized experiment, where it is possible to look deeper into each single physical process. The present paper concentrates on the initial triggering mechanism of the polar mesocyclone. As it is reported by many researchers, some mesocyclones are formed by the surface forcing, namely the uneven distribution of heat fluxes. That feature is common on the ice boundaries [2], where intense air stream flows from the cold ice surface to the warm sea surface. Hence, the resulting conditions are shallow baroclinicity and strong surface heat fluxes, which provide an arising polar mesocyclone with potential energy source converting it to the kinetic energy of the vortex. It is shown in this paper that different surface characteristics, including thermal parameters and, for example, the shape of an ice edge, determine an initial phase of a polar low life cycle. Moreover, it is shown what initial atmospheric state is most preferable for the formation of a new polar mesocyclone or in maintaining and reinforcing the existing one. The study is based on idealized high-resolution (~2 km) numerical experiment in which baroclinicity, stratification, initial wind profile and disturbance, surface

Probing sub-GeV dark matter-baryon scattering with cosmological observables

NASA Astrophysics Data System (ADS)

Xu, Weishuang Linda; Dvorkin, Cora; Chael, Andrew

2018-05-01

We derive new limits on the elastic scattering cross section between baryons and dark matter using cosmic microwave background data from the Planck satellite and measurements of the Lyman-alpha forest flux power spectrum from the Sloan Digital Sky Survey. Our analysis addresses generic cross sections of the form σ ∝vn , where v is the dark matter-baryon relative velocity, allowing for constraints on the cross section independent of specific particle physics models. We include high-ℓ polarization data from Planck in our analysis, improving over previous constraints. We apply a more careful treatment of dark matter thermal evolution than previously done, allowing us to extend our constraints down to dark matter masses of ˜MeV . We show in this work that cosmological probes are complementary to current direct detection and astrophysical searches.

AIM being prepared for integrated testing and flight simulation

NASA Image and Video Library

2007-03-24

At North Vandenberg Air Force Base in California, the AIM spacecraft has been rotated to horizontal prior to its move to the clean room for testing. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to its launch vehicle, Orbital Sciences' Pegasus XL, during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

AIM being prepared for integrated testing and flight simulation

NASA Image and Video Library

2007-03-24

Flight simulation No. 3 is on the schedule for the Pegasus XL launch vehicle, seen here in Building 1555 on North Vandenberg Air Force Base in California. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to its launch vehicle, Orbital Sciences' Pegasus XL, during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

KSC-07pd0973

NASA Image and Video Library

2007-04-16

KENNEDY SPACE CENTER, FLA. -- The mated Pegasus XL rocket - AIM spacecraft is moved onto a transporter in Building 1655 at Vandenberg Air Force Base in California. The launch vehicle will be transferred to a waiting Orbital Sciences Stargazer L-1011 aircraft for launch. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. Launch is scheduled for April 25.

AIM being prepared for integrated testing and flight simulation

NASA Image and Video Library

2007-03-24

In Building 1555 on North Vandenberg Air Force Base in California, technicians work on the separation system to be mated to the AIM spacecraft. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to its launch vehicle, Orbital Sciences' Pegasus XL, during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

AIM being prepared for integrated testing and flight simulation

NASA Image and Video Library

2007-03-24

In Building 1555 on North Vandenberg Air Force Base in California, technicians look over the spacecraft handling fixture that will be used to lift the AIM spacecraft. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to its launch vehicle, Orbital Sciences' Pegasus XL, during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

KSC-07pd0793

NASA Image and Video Library

2007-03-27

KENNEDY SPACE CENTER, FLA. -- At North Vandenberg Air Force Base in California, the AIM spacecraft is prepared for its move to the clean room for testing. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to its launch vehicle, Orbital Sciences' Pegasus XL, during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

Orbital Sciences Pegasus XL AIM Processing

NASA Image and Video Library

2007-03-10

Inside a clean room at Vandenberg Air Force Base in California, NASA's Aeronomy of Ice in the Mesosphere, or AIM, spacecraft is weighed. AIM is the seventh Small Explorers mission under NASA's Explorer Program. The program provides frequent flight opportunities for world-class scientific investigations from space within heliophysics and astrophysics. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to the Pegasus XL during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

KSC-07pd0794

NASA Image and Video Library

2007-03-27

KENNEDY SPACE CENTER, FLA. -- At North Vandenberg Air Force Base in California, the AIM spacecraft is moved into a clean room for testing. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to its launch vehicle, Orbital Sciences' Pegasus XL, during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

KSC-07pd0791

NASA Image and Video Library

2007-03-24

KENNEDY SPACE CENTER, FLA. -- In Building 1555 on North Vandenberg Air Force Base in California, technicians roll the AIM spacecraft back under the protective clean tent. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to its launch vehicle, Orbital Sciences' Pegasus XL, during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

AIM being prepared for integrated testing and flight simulation

NASA Image and Video Library

2007-03-24

In Building 1555 on North Vandenberg Air Force Base in California, technicians work on the separation system to be mated to the AIM spacecraft, hovering above it. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to its launch vehicle, Orbital Sciences' Pegasus XL, during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

The mated Pegasus XL rocket - AIM spacecraft leaves Building 165

NASA Image and Video Library

2007-04-16

The mated Pegasus XL rocket - AIM spacecraft is moved onto a transporter in Building 1655 at Vandenberg Air Force Base in California. The launch vehicle will be transferred to a waiting Orbital Sciences Stargazer L-1011 aircraft for launch. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. Launch is scheduled for April 25.

AIM being prepared for integrated testing and flight simulation

NASA Image and Video Library

2007-03-24

In Building 1555 on North Vandenberg Air Force Base in California, technicians lift the AIM spacecraft via the spacecraft handling fixture attached to it. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to its launch vehicle, Orbital Sciences' Pegasus XL, during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

AIM being prepared for integrated testing and flight simulation

NASA Image and Video Library

2007-03-24

In Building 1555 on North Vandenberg Air Force Base in California, technicians roll the AIM spacecraft back under the protective clean tent. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to its launch vehicle, Orbital Sciences' Pegasus XL, during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

AIM being prepared for integrated testing and flight simulation

NASA Image and Video Library

2007-03-24

In Building 1555 on North Vandenberg Air Force Base in California, technicians maneuver the spacecraft handling fixture toward the AIM spacecraft. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to its launch vehicle, Orbital Sciences' Pegasus XL, during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

Orbital Sciences Pegasus XL AIM Arrival

NASA Image and Video Library

2007-03-10

NASA's Aeronomy of Ice in the Mesosphere, or AIM, spacecraft arrives in a clean room at Vandenberg Air Force Base in California. AIM is the seventh Small Explorers mission under NASA's Explorer Program. The program provides frequent flight opportunities for world-class scientific investigations from space within heliophysics and astrophysics. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to the Pegasus XL during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

AIM being prepared for integrated testing and flight simulation

NASA Image and Video Library

2007-03-24

At North Vandenberg Air Force Base in California, the AIM spacecraft is prepared for its move to the clean room for testing. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to its launch vehicle, Orbital Sciences' Pegasus XL, during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

AIM being prepared for integrated testing and flight simulation

NASA Image and Video Library

2007-03-24

In Building 1555 on North Vandenberg Air Force Base in California, technicians lower the spacecraft handling fixture around the AIM spacecraft. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to its launch vehicle, Orbital Sciences' Pegasus XL, during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

The third stage of the Orbital Sciences Pegasus XL rocket is bei

NASA Image and Video Library

2007-04-03

At Vandenberg Air Force Base in California, technicians prepare to mate the AIM spacecraft (at left) to the SoftRide isolation system on the Orbital Sciences Pegasus XL rocket. The Cosmic Dust Experiment surfaces can be clearly seen as 12 rectangular areas on the aft portion of the spacecraft. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. Launch from the Pegasus XL rocket is scheduled for April 25.

KSC-07pd0974

NASA Image and Video Library

2007-04-16

KENNEDY SPACE CENTER, FLA. -- The mated Pegasus XL rocket - AIM spacecraft is secured onto a transporter at Vandenberg Air Force Base in California. The rocket will be transferred to a waiting Orbital Sciences Stargazer L-1011 aircraft for launch. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. Launch is scheduled for April 25.

KSC-07pd0786

NASA Image and Video Library

2007-03-24

KENNEDY SPACE CENTER, FLA. -- In Building 1555 on North Vandenberg Air Force Base in California, technicians lower the spacecraft handling fixture around the AIM spacecraft. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to its launch vehicle, Orbital Sciences' Pegasus XL, during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

AIM being prepared for integrated testing and flight simulation

NASA Image and Video Library

2007-03-24

In Building 1555 on North Vandenberg Air Force Base in California, technicians lower the AIM spacecraft onto a moveable stand. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to its launch vehicle, Orbital Sciences' Pegasus XL, during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

AIM being prepared for integrated testing and flight simulation

NASA Image and Video Library

2007-03-24

At North Vandenberg Air Force Base in California, the AIM spacecraft is moved into a clean room for testing. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to its launch vehicle, Orbital Sciences' Pegasus XL, during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

AIM being prepared for integrated testing and flight simulation

NASA Image and Video Library

2007-03-24

In Building 1555 on North Vandenberg Air Force Base in California, technicians move a mobile stand toward the AIM spacecraft suspended via a crane at left. . AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to its launch vehicle, Orbital Sciences' Pegasus XL, during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

KSC-07pd0789

NASA Image and Video Library

2007-03-24

KENNEDY SPACE CENTER, FLA. -- In Building 1555 on North Vandenberg Air Force Base in California, technicians lower the AIM spacecraft onto a moveable stand. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to its launch vehicle, Orbital Sciences' Pegasus XL, during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

KSC-07pd0785

NASA Image and Video Library

2007-03-24

KENNEDY SPACE CENTER, FLA. -- In Building 1555 on North Vandenberg Air Force Base in California, technicians maneuver the spacecraft handling fixture toward the AIM spacecraft. AIM, which stands for Aeronomy of Ice in the Mesosphere, is being prepared for integrated testing and a flight simulation. The AIM spacecraft will fly three instruments designed to study polar mesospheric clouds located at the edge of space, 50 miles above the Earth's surface in the coldest part of the planet's atmosphere. The mission's primary goal is to explain why these clouds form and what has caused them to become brighter and more numerous and appear at lower latitudes in recent years. AIM's results will provide the basis for the study of long-term variability in the mesospheric climate and its relationship to global climate change. AIM is scheduled to be mated to its launch vehicle, Orbital Sciences' Pegasus XL, during the second week of April, after which final inspections will be conducted. Launch is scheduled for April 25.

Indirect searches of dark matter via polynomial spectral features

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia-Cely, Camilo; Heeck, Julian

2016-08-11

We derive the spectra arising from non-relativistic dark matter annihilations or decays into intermediary particles with arbitrary spin, which subsequently produce neutrinos or photons via two-body decays. Our approach is model independent and predicts spectral features restricted to a kinematic box. The overall shape within that box is a polynomial determined by the polarization of the decaying particle. We illustrate our findings with two examples. First, with the neutrino spectra arising from dark matter annihilations into the massive Standard Model gauge bosons. Second, with the gamma-ray and neutrino spectra generated by dark matter annihilations into hypothetical massive spin-2 particles. Ourmore » results are in particular applicable to the 750 GeV diphoton excess observed at the LHC if interpreted as a spin-0 or spin-2 particle coupled to dark matter. We also derive limits on the dark matter annihilation cross section into this resonance from the non-observation of the associated gamma-ray spectral features by the H.E.S.S. telescope.« less

JPL Closeup

NASA Technical Reports Server (NTRS)

1983-01-01

Voyager, Infrared Astronomical Satellite, Galileo, Viking, Solar Mesosphere Explorer, Wide-field/Planetary Camera, Venus Mapper, International Solar Polar Mission - Solar Interplanetary Satellite, Extreme Ultraviolet Explores, Starprobe, International Halley Watch, Marine Mark II, Samex, Shuttle Imaging Radar-A, Deep Space Network, Biomedical Technology, Ocean Studies and Robotics are summarized.

Estimating pesticide sampling rates by the polar organic chemical integrative sampler (POCIS) in the presence of natural organic matter and varying hydrodynamic conditions.

PubMed

Charlestra, Lucner; Amirbahman, Aria; Courtemanch, David L; Alvarez, David A; Patterson, Howard

2012-10-01

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 (R(s)) was evaluated in microcosms containing <0.1-5 mg L(-1) of total organic carbon (TOC). The effect of hydrodynamics was studied by comparing R(s) 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. Copyright © 2012 Elsevier Ltd. All rights reserved.

Cosmic Ray Experiments and the Implications for Indirect Detection of Dark Matter

NASA Technical Reports Server (NTRS)

Mitchell, John W.; Ormes, Jonathan F.; Streitmatter, Robert E.

2013-01-01

Detection of cosmic-ray antiprotons was first reported by Golden et al. in 1979 and their existence was firmly established by the BESS and IMAX collaborations in the early 1990s. Increasingly precise measurements of the antiproton spectrum, most recently from BESS-Polar and PAMELA, have made it an important tool for investigating cosmic-ray transport in the galaxy and heliosphere and for constraining dark-matter models. The history of antiproton measurements will be briefly reviewed. The current status will be discussed, focusing on the results of BESS-Polar II and their implications for the possibility of antiprotons from primordial black hole evaporation. The current results of the BESS-Polar II antihelium search are also presented.

What can we learn from simulating Stratospheric Sudden Warming periods with the Thermosphere-Ionosphere-Mesosphere-Electrodynamics GCM?

NASA Astrophysics Data System (ADS)

Maute, A. I.; Hagan, M. E.; Roble, R. G.; Richmond, A. D.; Yudin, V. A.; Liu, H.; Goncharenko, L. P.; Burns, A. G.; Maruyama, N.

2013-12-01

The ionosphere-thermosphere system is not only influenced from geospace but also by meteorological variability. Ionospheric observations of GPS TEC during the current solar cycle have shown that the meteorological variability is important during solar minimum, but also can have significant ionospheric effects during solar medium to maximum conditions. Numerical models can be used to help understand the mechanisms that couple the lower and upper atmosphere over the solar cycle. Numerical modelers invoke different methods to simulate realistic, specified events of meteorological variability, e.g. specify the lower boundary forcing, nudge the middle atmosphere, data assimilation. To study the vertical coupling, we first need to assess the numerical models and the various methods used to simulate realistic events with respect to the dynamics of the mesosphere-lower thermosphere (MLT) region, the electrodynamics, and the ionosphere. This study focuses on Stratospheric Sudden Warming (SSW) periods since these are associated with a strongly disturbed middle atmosphere which can have effects up to the ionosphere. We will use the NCAR Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation model (TIME-GCM) to examine several recent SSW periods, e.g. 2009, 2012, and 2013. The SSW period in TIME-GCM will be specified in three different ways: 1. using reanalysis data to specify the lower boundary; 2. nudging the neutral atmosphere (temperature and winds) with the Whole Atmosphere Community Climate Model (WACCM)/Goddard Earth Observing System Model, Version 5 (GEOS-5) results; 3. nudging the background atmosphere (temperature and winds) with WACCM/GEOS5 results. The different forcing methods will be evaluated for the SSW periods with respect to the dynamics of the MLT region, the low latitude vertical drift changes, and the ionospheric effects for the different SSW periods. With the help of ionospheric data at different longitudinal sectors it will be possible to

Daily estimates of the migrating tide and zonal mean temperature in the mesosphere and lower thermosphere derived from SABER data

NASA Astrophysics Data System (ADS)

Ortland, David A.

2017-04-01

Satellites provide a global view of the structure in the fields that they measure. In the mesosphere and lower thermosphere, the dominant features in these fields at low zonal wave number are contained in the zonal mean, quasi-stationary planetary waves, and tide components. Due to the nature of the satellite sampling pattern, stationary, diurnal, and semidiurnal components are aliased and spectral methods are typically unable to separate the aliased waves over short time periods. This paper presents a data processing scheme that is able to recover the daily structure of these waves and the zonal mean state. The method is validated by using simulated data constructed from a mechanistic model, and then applied to Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) temperature measurements. The migrating diurnal tide extracted from SABER temperatures for 2009 has a seasonal variability with peak amplitude (20 K at 95 km) in February and March and minimum amplitude (less than 5 K at 95 km) in early June and early December. Higher frequency variability includes a change in vertical structure and amplitude during the major stratospheric warming in January. The migrating semidiurnal tide extracted from SABER has variability on a monthly time scale during January through March, minimum amplitude in April, and largest steady amplitudes from May through September. Modeling experiments were performed that show that much of the variability on seasonal time scales in the migrating tides is due to changes in the mean flow structure and the superposition of the tidal responses to water vapor heating in the troposphere and ozone heating in the stratosphere and lower mesosphere.

Hydrodynamics of soft active matter

NASA Astrophysics Data System (ADS)

Marchetti, M. C.; Joanny, J. F.; Ramaswamy, S.; Liverpool, T. B.; Prost, J.; Rao, Madan; Simha, R. Aditi

2013-07-01

This review summarizes theoretical progress in the field of active matter, placing it in the context of recent experiments. This approach offers a unified framework for the mechanical and statistical properties of living matter: biofilaments and molecular motors in vitro or in vivo, collections of motile microorganisms, animal flocks, and chemical or mechanical imitations. A major goal of this review is to integrate several approaches proposed in the literature, from semimicroscopic to phenomenological. In particular, first considered are “dry” systems, defined as those where momentum is not conserved due to friction with a substrate or an embedding porous medium. The differences and similarities between two types of orientationally ordered states, the nematic and the polar, are clarified. Next, the active hydrodynamics of suspensions or “wet” systems is discussed and the relation with and difference from the dry case, as well as various large-scale instabilities of these nonequilibrium states of matter, are highlighted. Further highlighted are various large-scale instabilities of these nonequilibrium states of matter. Various semimicroscopic derivations of the continuum theory are discussed and connected, highlighting the unifying and generic nature of the continuum model. Throughout the review, the experimental relevance of these theories for describing bacterial swarms and suspensions, the cytoskeleton of living cells, and vibrated granular material is discussed. Promising extensions toward greater realism in specific contexts from cell biology to animal behavior are suggested, and remarks are given on some exotic active-matter analogs. Last, the outlook for a quantitative understanding of active matter, through the interplay of detailed theory with controlled experiments on simplified systems, with living or artificial constituents, is summarized.

Quasi two day wave-related variability in the background dynamics and composition of the mesosphere/thermosphere and the ionosphere

PubMed Central

Chang, Loren C; Yue, Jia; Wang, Wenbin; Wu, Qian; Meier, R R

2014-01-01

Dissipating planetary waves in the mesosphere/lower thermosphere (MLT) region may cause changes in the background dynamics of that region, subsequently driving variability throughout the broader thermosphere/ionosphere system via mixing due to the induced circulation changes. We report the results of case studies examining the possibility of such coupling during the northern winter in the context of the quasi two day wave (QTDW)—a planetary wave that recurrently grows to large amplitudes from the summer MLT during the postsolstice period. Six distinct QTDW events between 2003 and 2011 are identified in the MLT using Sounding of the Atmosphere using Broadband Emission Radiometry temperature observations. Concurrent changes to the background zonal winds, zonal mean column O/N2 density ratio, and ionospheric total electron content (TEC) are examined using data sets from Thermosphere Ionosphere Mesosphere Energetics and Dynamics Doppler Interferometer, Global Ultraviolet Imager, and Global Ionospheric Maps, respectively. We find that in the 5–10 days following a QTDW event, the background zonal winds in the MLT show patterns of eastward and westward anomalies in the low and middle latitudes consistent with past modeling studies on QTDW-induced mean wind forcing, both below and at turbopause altitudes. This is accompanied by potentially related decreases in zonal mean thermospheric column O/N2, as well as to low-latitude TECs. The recurrent nature of the above changes during the six QTDW events examined point to an avenue for vertical coupling via background dynamics and chemistry of the thermosphere/ionosphere not previously observed. Key Points Dissipating planetary waves (PWs) in the MLT can drive background wind changes Mixing from dissipating PWs drive thermosphere/ionosphere composition changes First observations of QTDW-driven variability from this mechanism PMID:26312201

Quasi two day wave-related variability in the background dynamics and composition of the mesosphere/thermosphere and the ionosphere.

PubMed

Chang, Loren C; Yue, Jia; Wang, Wenbin; Wu, Qian; Meier, R R

2014-06-01

Dissipating planetary waves in the mesosphere/lower thermosphere (MLT) region may cause changes in the background dynamics of that region, subsequently driving variability throughout the broader thermosphere/ionosphere system via mixing due to the induced circulation changes. We report the results of case studies examining the possibility of such coupling during the northern winter in the context of the quasi two day wave (QTDW)-a planetary wave that recurrently grows to large amplitudes from the summer MLT during the postsolstice period. Six distinct QTDW events between 2003 and 2011 are identified in the MLT using Sounding of the Atmosphere using Broadband Emission Radiometry temperature observations. Concurrent changes to the background zonal winds, zonal mean column O/N 2 density ratio, and ionospheric total electron content (TEC) are examined using data sets from Thermosphere Ionosphere Mesosphere Energetics and Dynamics Doppler Interferometer, Global Ultraviolet Imager, and Global Ionospheric Maps, respectively. We find that in the 5-10 days following a QTDW event, the background zonal winds in the MLT show patterns of eastward and westward anomalies in the low and middle latitudes consistent with past modeling studies on QTDW-induced mean wind forcing, both below and at turbopause altitudes. This is accompanied by potentially related decreases in zonal mean thermospheric column O/N 2 , as well as to low-latitude TECs. The recurrent nature of the above changes during the six QTDW events examined point to an avenue for vertical coupling via background dynamics and chemistry of the thermosphere/ionosphere not previously observed. Dissipating planetary waves (PWs) in the MLT can drive background wind changesMixing from dissipating PWs drive thermosphere/ionosphere composition changesFirst observations of QTDW-driven variability from this mechanism.

Numerical simulations of the seasonal/latitudinal variations of atomic oxygen and nitric oxide in the lower thermosphere and mesosphere

NASA Technical Reports Server (NTRS)

Rees, D.; Fuller-Rowell, T. J.

1989-01-01

A 2-Dimensional zonally-averaged thermospheric model and the global University College London (UCL) thermospheric model have been used to investigate the seasonal, solar activity and geomagnetic variation of atomic oxygen and nitric oxide. The 2-dimensional model includes detailed oxygen and nitrogen chemistry, with appropriate completion of the energy equation, by adding the thermal infrared cooling by O and NO. This solution includes solar and auroral production of odd nitrogen compounds and metastable species. This model has been used for three investigations; firstly, to study the interactions between atmospheric dynamics and minor species transport and density; secondly, to examine the seasonal variations of atomic oxygen and nitric oxide within the upper mesosphere and thermosphere and their response to solar and geomagnetic activity variations; thirdly, to study the factor of 7 to 8 peak nitric oxide density increase as solar F sub 10.7 cm flux increases from 70 to 240 reported from the Solar Mesospheric Explorer. Auroral production of NO is shown to be the dominant source at high latitudes, generating peak NO densities a factor of 10 greater than typical number densities at low latitudes. At low latitudes, the predicted variation of the peak NO density, near 110 km, with the solar F sub 10.7 cm flux is rather smaller than is observed. This is most likely due to an overestimate of the soft X-ray flux at low solar activity, for times of extremely low support number, as occurred in June 1986. As observed on pressure levels, the variation of O density is small. The global circulation during solstice and periods of elevated geomagnetic activity causes depletion of O in regions of upwelling, and enhancements in regions of downwelling.

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.;

Multiwaveband Polarimetric Observations of 15 Active Galactic Nuclei at High Frequencies: Correlated Polarization Behavior

NASA Astrophysics Data System (ADS)

Jorstad, Svetlana G.; Marscher, Alan P.; Stevens, Jason A.; Smith, Paul S.; Forster, James R.; Gear, Walter K.; Cawthorne, Timothy V.; Lister, Matthew L.; Stirling, Alastair M.; Gómez, José L.; Greaves, Jane S.; Robson, E. Ian

2007-08-01

We report on multifrequency linear polarization monitoring of 15 active galactic nuclei containing highly relativistic jets with apparent speeds from ~4c to >40c. The measurements were obtained at optical, 1 mm, and 3 mm wavelengths, and at 7 mm with the Very Long Baseline Array. The data show a wide range in degree of linear polarization among the sources, from <1% to >30%, and interday polarization variability in individual sources. The polarization properties suggest separation of the sample into three groups with low, intermediate, and high variability of polarization in the core at 7 mm (LVP, IVP, and HVP, respectively). The groups are partially associated with the common classification of active galactic nuclei as radio galaxies and quasars with low optical polarization (LVP), BL Lacertae objects (IVP), and highly optically polarized quasars (HVP). Our study investigates correlations between total flux, fractional polarization, and polarization position angle at the different wavelengths. We interpret the polarization properties of the sources in the sample through models in which weak shocks compress turbulent plasma in the jet. The differences in the orientation of sources with respect to the observer, jet kinematics, and abundance of thermal matter external to the jet near the core can account for the diversity in the polarization properties. The results provide strong evidence that the optical polarized emission originates in shocks, most likely situated between the 3 and 7 mm VLBI cores. They also support the idea that the 1 mm core lies at the edge of the transition zone between electromagnetically dominated and turbulent hydrodynamic sections of the jet.

Measurement of winds in Venus' upper mesosphere based on Doppler shifts of the 2.6-mm (C-12)O line

NASA Technical Reports Server (NTRS)

Shah, Kathryn P.; Muhleman, Duane O.; Berge, Glenn L.

1991-01-01

Venus observations conducted in 1988 at the first rotational transition of (C-12)O finely sampled this absorption line by means of a 32-channel filter bank; with this spatial and spectral resolution, it proved possible to measure Doppler shifts of the absorption line across the planet due to strong winds in Venus' upper mesosphere. The Doppler shifts change in a way that is indicative of westward horizontal winds. The radial wind speeds from the Doppler shifts were smoothed to reduce noise and then fitted in least-squares fashion to canonical forms of the lower atmosphere's westward zonal flow. The two flows exhibit a high correlation in orientation.

Telecom-Wavelength Atomic Quantum Memory in Optical Fiber for Heralded Polarization Qubits.

PubMed

Jin, Jeongwan; Saglamyurek, Erhan; Puigibert, Marcel lí Grimau; Verma, Varun; Marsili, Francesco; Nam, Sae Woo; Oblak, Daniel; Tittel, Wolfgang

2015-10-02

Polarization-encoded photons at telecommunication wavelengths provide a compelling platform for practical realizations of photonic quantum information technologies due to the ease of performing single qubit manipulations, the availability of polarization-entangled photon-pair sources, and the possibility of leveraging existing fiber-optic links for distributing qubits over long distances. An optical quantum memory compatible with this platform could serve as a building block for these technologies. Here we present the first experimental demonstration of an atomic quantum memory that directly allows for reversible mapping of quantum states encoded in the polarization degree of freedom of a telecom-wavelength photon. We show that heralded polarization qubits at a telecom wavelength are stored and retrieved with near-unity fidelity by implementing the atomic frequency comb protocol in an ensemble of erbium atoms doped into an optical fiber. Despite remaining limitations in our proof-of-principle demonstration such as small storage efficiency and storage time, our broadband light-matter interface reveals the potential for use in future quantum information processing.

A dual polarized antenna system using a meanderline polarizer

NASA Technical Reports Server (NTRS)

Burger, H. A.

1978-01-01

Certain applications of synthetic aperture radars require transmitting on one linear polarization and receiving on two orthogonal linear polarizations for adequate characterization of the surface. To meet the current need at minimum cost, it was desirable to use two identical horizontally polarized shaped beam antennas and to change the polarization of one of them by a polarization conversion plate. The plate was realized as a four-layer meanderline polarizer designed to convert horizontal polarization to vertical.

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

Large-amplitude mesospheric response to an orographic wave generated over the Southern Ocean Auckland Islands (50.7°S) during the DEEPWAVE project

NASA Astrophysics Data System (ADS)

Pautet, P.-D.; Taylor, M. J.; Fritts, D. C.; Bossert, K.; Williams, B. P.; Broutman, D.; Ma, J.; Eckermann, S. D.; Doyle, J. D.

2016-02-01

The Deep Propagating Gravity Wave Experiment (DEEPWAVE) project was conducted over New Zealand and the surrounding regions during June and July 2014, to more fully understand the generation, propagation, and effects of atmospheric gravity waves. A large suite of instruments collected data from the ground to the upper atmosphere (~100 km), with several new remote-sensing instruments operating on board the NSF Gulfstream V (GV) research aircraft, which was the central measurement platform of the project. On 14 July, during one of the research flights (research flight 23), a spectacular event was observed as the GV flew in the lee of the sub-Antarctic Auckland Islands (50.7°S). An apparent "ship wave" pattern was imaged in the OH layer (at ~83.5 km) by the Utah State University Advanced Mesospheric Temperature Mapper and evolved significantly over four successive passes spanning more than 4 h. The waves were associated with orographic forcing generated by relatively strong (15-20 m/s) near-surface wind flowing over the rugged island topography. The mountain wave had an amplitude T' ~ 10 K, a dominant horizontal wavelength ~40 km, achieved a momentum flux exceeding 300 m2 s-2, and eventually exhibited instability and breaking at the OH altitude. This case of deep mountain wave propagation demonstrates the potential for strong responses in the mesosphere arising from a small source under suitable propagation conditions and suggests that such cases may be more common than previously believed.

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.

Three-dimensional polarization algebra for all polarization sensitive optical systems.

PubMed

Li, Yahong; Fu, Yuegang; Liu, Zhiying; Zhou, Jianhong; Bryanston-Cross, P J; Li, Yan; He, Wenjun

2018-05-28

Using three-dimensional (3D) coherency vector (9 × 1), we develop a new 3D polarization algebra to calculate the polarization properties of all polarization sensitive optical systems, especially when the incident optical field is partially polarized or un-polarized. The polarization properties of a high numerical aperture (NA) microscope objective (NA = 1.25 immersed in oil) are analyzed based on the proposed 3D polarization algebra. Correspondingly, the polarization simulation of this high NA optical system is performed by the commercial software VirtualLAB Fusion. By comparing the theoretical calculations with polarization simulations, a perfect matching relation is obtained, which demonstrates that this 3D polarization algebra is valid to quantify the 3D polarization properties for all polarization sensitive optical systems.

Using fluorescent dissolved organic matter to trace and distinguish the origin of Arctic surface waters

PubMed Central

Gonçalves-Araujo, Rafael; Granskog, Mats A.; Bracher, Astrid; Azetsu-Scott, Kumiko; Dodd, Paul A.; Stedmon, Colin A.

2016-01-01

Climate change affects the Arctic with regards to permafrost thaw, sea-ice melt, alterations to the freshwater budget and increased export of terrestrial material to the Arctic Ocean. The Fram and Davis Straits represent the major gateways connecting the Arctic and Atlantic. Oceanographic surveys were performed in the Fram and Davis Straits, and on the east Greenland Shelf (EGS), in late summer 2012/2013. Meteoric (fmw), sea-ice melt, Atlantic and Pacific water fractions were determined and the fluorescence properties of dissolved organic matter (FDOM) were characterized. In Fram Strait and EGS, a robust correlation between visible wavelength fluorescence and fmw was apparent, suggesting it as a reliable tracer of polar waters. However, a pattern was observed which linked the organic matter characteristics to the origin of polar waters. At depth in Davis Strait, visible wavelength FDOM was correlated to apparent oxygen utilization (AOU) and traced deep-water DOM turnover. In surface waters FDOM characteristics could distinguish between surface waters from eastern (Atlantic + modified polar waters) and western (Canada-basin polar waters) Arctic sectors. The findings highlight the potential of designing in situ multi-channel DOM fluorometers to trace the freshwater origins and decipher water mass mixing dynamics in the region without laborious samples analyses. PMID:27667721

Imaging of polarized target in underwater environment

NASA Astrophysics Data System (ADS)

Carrizo, Carlos; Foster, Robert; El-Habashi, Ahmed; Gray, Deric; Gilerson, Alex

2017-10-01

Imaging of underwater targets is challenging because of the significant attenuation of the propagating light field due to the absorption and scattering by water and suspended/dissolved matter. Some living and manmade objects in water have surfaces which partially polarize the light, whose properties can be used to camouflage or, conversely, to detect such objects. The attenuation of light by the intervening water (so-called veiling light) changes both the intensity and polarization characteristics at each pixel of the image, but does not contain any information about the target and contributes to image degradation and blurring. Its properties need to be understood in order to isolate the true optical signature of the target. The main goal of this study is to retrieve the polarization characteristics of the target from the image in different water environmental and illumination conditions by taking into account coincidentally measured inherent water optical properties (IOPs) during recent field campaigns outside the Chesapeake Bay and in New York Bight. Data, in the form of images and videos, were acquired using a green-band full-Stokes polarimetric video camera. Analysis of the acquired images show reasonable agreement in Stokes vector components with the measurements by the underwater polarimeter and modeled polarized signals. In addition, Stokes vector components of the veiling light were also estimated and compared with the models. Finally, retrieval of the attenuation coefficient for the light from the target is attempted from the measurements and compared with the results of the independent measurements of IOPs.

Dark Matter in the Universe and in the Galaxy

NASA Technical Reports Server (NTRS)

Kamionkowski, Marc

1999-01-01

During the past four years, Prof. Kamionkowski and collaborators have made progress in research on the nature and distribution of dark-matter in the Universe and in the Galaxy, and on related topics in astrophysics and cosmology. We have made progress on research on the cosmic microwave background, large-scale structure, issues related to particle dark matter, and the gamma-ray-burst enigma. A significant fraction of the research supported by this ATP has been on the cosmic microwave background (CMB). Prof. Kamionkowski and collaborators showed how the polarization of the CMB could be used to detect long-wavelength gravitational waves, such as those produced by inflation. With Kosowsky, Prof. Kamionkowski calculated the amplitude of a stochastic gravitational-wave background that could be detected for a satellite experiment of a given sensitivity and angular resolution. They showed that polarization should improve the sensitivity oa MAP to these gravity waves, and that the Planck Surveyor should do even better. Prof. Kamionkowski, Caldwell, and a student calculated and illustrated the CMB temperature/polarization pattern produced by a single plane-wave gravitational wave. They calculated the amplitude of such a wave that would be detectable with MAP and Planck, and compared that with the sensitivity of traditional gravitational-wave detectors like LIGO and LISA. With Lue and Wang, the PI showed how parity violation from new high-energy physics could conceivably give rise to an observable signature in the CMB polarization. With Loeb, Prof. Kamionkowski showed how measurement of the polarization of CMB photons scattered by hot gas in a cluster could be used to determine the quadrupole moment of the CMB incident on that cluster. Prof. Kamionkowski and Jaffe calculated the amplitude of secondary anisotropies produced by scattering of CMB photons from reionized regions. Research has also been carried out on probing the large-scale distribution of mass in the Universe

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.

Rayleigh-scatter lidar measurements of the mesosphere and thermosphere and their connections to sudden stratospheric warmings

NASA Astrophysics Data System (ADS)

Sox, Leda

The Earth's middle atmosphere (10-110 km) has long been a region in which measurement techniques are limited. Many ground-based and remote sensing satellite instruments have been developed over the past several decades, which strive to provide good coverage of this region. However, each of the different techniques has its own measurement limitations in the extent of its coverage in altitude, time, or global-scale. In order for researchers to trace geophysical dynamics and phenomena across the three regions in the middle atmosphere, measurements from many instruments often have to be spliced together. Rayleigh-scatter lidar is a ground-based remote sensing technique that has been used to acquire relative density and absolute temperature measurements throughout the 35-90 km region at several sites for the past four decades. Rayleigh lidars have a unique advantage over many other middle-atmosphere instruments in that their measurements do not have a theoretical limit to their altitude coverage. Their upper altitude limits are only constrained by technological advances in instrumentation and their lower limits are only constrained by the presence of aerosols (below about 35 km). However, Mie and Raman scatter detectors can be added to extend their measurements down to ground level. The Rayleigh lidar on the campus of Utah State University has recently been upgraded in such a way as to extend its upper altitude limit 25 km higher, into the lower thermosphere. The first year (2014-2015) of data acquired with this new system has been analyzed to obtain temperatures in the 70-115 km region. Numerical experiments were carried out that showed it was possible to compensate for changing atmospheric composition above 90 km with minimal effects on the derived Rayleigh temperatures. These new temperatures were in good agreement with temperatures from the previous version of the system and well-established results of the thermal structure in the mesosphere-lower thermosphere

Humic supramolecular structures have polar surfaces and unpolar cores in native soil.

PubMed

Fischer, Thomas

2017-09-01

It was the aim of our study to prove the hypothesis that humic substances (HS) in native soil are spatially arranged in descending order of polarity, meaning that highly polar supramolecular subunits shield less polar subunits against the free soil solution and form layers of descending polarity. To address this aim, we consecutively extracted humic substances from soil with 8 M (HS1), 4 M (HS2), 2 M (HS3), 1 M (HS4) and 0.5 M LiCl (HS5) solution in 0.2 M LiOH after Cu 2+ adsorption in batch soil column experiments. Adsorption was performed for 1, 10 and 60 min with concentrations ranging from 9.5 to 110 mg L -1 Cu 2+ in 0.02 M CaCl 2 solution. We assumed that high ionic strength facilitates extraction of most polar organic compounds, with polarity of the extracted HS decreasing with decreasing ionic strength, and that Cu extracted together with the successive HS solely formed coordination complexes, facilitating its use as a tracer for organic matter studies. We hypothesized a delayed Cu adsorption on the less polar fractions in case of spatial shielding due to interception on overlying fractions, and a concurrent Cu adsorption in case of random spatial arrangement. It was concluded that humic substances are shielded against each other in the order of descending polarity of the supramolecular subunits (free soil solution | HS1 | HS2 | HS3 | HS4 | HS5). Copyright © 2017 Elsevier Ltd. All rights reserved.

Continuum Foreground Polarization and Na I Absorption in Type Ia SNe

NASA Astrophysics Data System (ADS)

Zelaya, P.; Clocchiatti, A.; Baade, D.; Höflich, P.; Maund, J.; Patat, F.; Quinn, J. R.; Reilly, E.; Wang, L.; Wheeler, J. C.; Förster, F.; González-Gaitán, S.

2017-02-01

We present a study of the continuum polarization over the 400-600 nm range of 19 SNe Ia obtained with FORS at the VLT. We separate them into those that show Na I D lines at the velocity of their hosts and those that do not. Continuum polarization of the sodium sample near maximum light displays a broad range of values, from extremely polarized cases like SN 2006X to almost unpolarized ones like SN 2011ae. The non-sodium sample shows, typically, smaller polarization values. The continuum polarization of the sodium sample in the 400-600 nm range is linear with wavelength and can be characterized by the mean polarization ({P}{mean}). Its values span a wide range and show a linear correlation with color, color excess, and extinction in the visual band. Larger dispersion correlations were found with the equivalent width of the Na I D and Ca II H and K lines, and also a noisy relation between {P}{mean} and R V , the ratio of total to selective extinction. Redder SNe show stronger continuum polarization, with larger color excesses and extinctions. We also confirm that high continuum polarization is associated with small values of R V . The correlation between extinction and polarization—and polarization angles—suggest that the dominant fraction of dust polarization is imprinted in interstellar regions of the host galaxies. We show that Na I D lines from foreground matter in the SN host are usually associated with non-galactic ISM, challenging the typical assumptions in foreground interstellar polarization models. Based on observations made with ESO Telescopes at the Paranal Observatory under programs 068.D-0571(A), 069.D-0438(A), 070.D-0111(A), 076.D-0178(A), 079.D-0090(A), 080.D-0108(A), 081.D-0558(A), 085.D-0731(A), and 086.D-0262(A). Also based on observations collected at the German-Spanish Astronomical Center, Calar Alto (Spain).

Global Geospace Science/Polar Plasma Laboratory: POLAR

NASA Technical Reports Server (NTRS)

1996-01-01

The Global Geospace Science (GGS) Project is discussed as part of the International Solar-Terrestrial Physics (ISTP) Science Initiative. The objectives of Polar Plasma Laboratory (POLAR), one of the two spacecraft to be used by the Project to fill critical gaps in the scientific understanding of solar and plasma physics, are outlined. POLAR Laboratory is described, along with POLAR instrumentation, support subsystems, and orbits. Launch vehicle and injection into orbit are also addressed.

Structure and seasonal variations of the nocturnal mesospheric K layer at Arecibo

NASA Astrophysics Data System (ADS)

Yue, Xianchang; Friedman, Jonathan S.; Wu, Xiongbin; Zhou, Qihou H.

2017-07-01

We present the seasonal variations of the nocturnal mesospheric potassium (K) layer at Arecibo, Puerto Rico (18.35°N, 66.75°W) from 160 nights of K Doppler lidar observations between December 2003 and January 2010, during which the solar activity is mostly low. The background temperature is also measured simultaneously by the lidar and shows a strong semiannual oscillation with maxima occurring during equinoxes at all altitudes. The annual mean K density profile is approximately Gaussian with a peak altitude of 91.7 km. The K column abundance and the centroid height have strong semiannual variations, with maxima at the solstices. Both parameters are negatively correlated to the mean background temperature with a correlation coefficient < -0.5. The root-mean-square (RMS) width has a distinct annual oscillation with the largest width occurring in May. The seasonal variation of the centroid height is similar to that of the Fe layer at the same site. The seasonal temperature variation indicates significant enhanced wave-induced downward transport for both species during spring and autumn. This explains the metal layer centroid height and column abundance variations at Arecibo and provides a general mechanism to account for the seasonal variations in the centroid height of all metal species measured at low-latitude and midlatitude sites.

Case study of mesospheric front dissipation observed over the northeast of Brazil

NASA Astrophysics Data System (ADS)

Fragoso Medeiros, Amauri; Paulino, Igo; Wrasse, Cristiano Max; Fechine, Joaquim; Takahashi, Hisao; Valentin Bageston, José; Paulino, Ana Roberta; Arlen Buriti, Ricardo

2018-03-01

On 3 October 2005 a mesospheric front was observed over São João do Cariri (7.4° S, 36.5° W). This front propagated to the northeast and appeared in the airglow images on the west side of the observatory. By about 1.5 h later, it dissipated completely when the front crossed the local zenith. Ahead of the front, several ripple structures appeared during the dissipative process of the front. Using coincident temperature profile from the TIMED/SABER satellite and wind profiles from a meteor radar at São João do Cariri, the background of the atmosphere was investigated in detail. On the one hand, it was noted that a strong vertical wind shear in the propagation direction of the front produced by a semidiunal thermal tide was mainly responsible for the formation of duct (Doppler duct), in which the front propagated up to the zenith of the images. On the other hand, the evolution of the Richardson number as well as the appearance of ripples ahead of the main front suggested that a presence of instability in the airglow layer that did not allow the propagation of the front to the other side of the local zenith.

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.

When measured spin polarization is not spin polarization

NASA Astrophysics Data System (ADS)

Dowben, P. A.; Wu, Ning; Binek, Christian

2011-05-01

Spin polarization is an unusually ambiguous scientific idiom and, as such, is rarely well defined. A given experimental methodology may allow one to quantify a spin polarization but only in its particular context. As one might expect, these ambiguities sometimes give rise to inappropriate interpretations when comparing the spin polarizations determined through different methods. The spin polarization of CrO2 and Cr2O3 illustrate some of the complications which hinders comparisons of spin polarization values.