Science.gov

Sample records for airglow imaging observations

  1. Atmospheric gravity waves observed in OH airglow images from 78°N

    NASA Astrophysics Data System (ADS)

    Dyrland, M. E.; Holmen, S. E.; Sigernes, F.; Taylor, M. J.; Pautet, P.; Hall, C. M.; Tsutsumi, M.; Lorentzen, D. A.

    2012-12-01

    Atmospheric gravity waves play an essential role in determining the global circulation and thermal balance of the atmosphere. Airglow imagers are important tools for characterizing atmospheric gravity waves in the mesopause region and there are few placed in High Arctic locations. An airglow imager was installed at the Kjell Henriksen Observatory (KHO) located close to Longyearbyen on the Norwegian Arctic archipelago Svalbard (78°N, 16°E) in November 2010. The imager has a wide band filter and also bandpass filters to obtain the intensity of two different rotational lines of the OH(6-2) vibrational band. Two winter seasons of airglow data (2010/2011 and 2011/2012) have been analyzed. From the 395 measurement days, only about 17% had clear sky periods. Analysis of the images with low auroral contamination shows that gravity waves can be detected by the imager, however the number of wave events observed were relatively few. The characteristics of the observed waves have been found by FFT analysis. By using mesospheric wind data from the nearby Nippon/Norway Svalbard Meteor Radar (NSMR), the intrinsic properties of the gravity waves have also been retrieved. The predominant propagation direction of the gravity waves observed is northwestward. Temperatures obtained from combining the observed ratio of the bandpass images and background intensity measured by a co-located spectrometer is also presented.

  2. Concentric gravity waves over northern China observed by an airglow imager network and satellites

    NASA Astrophysics Data System (ADS)

    Xu, Jiyao; Li, Qinzeng; Yue, Jia; Hoffmann, Lars; Straka, William C.; Wang, Cuimei; Liu, Mohan; Yuan, Wei; Han, Sai; Miller, Steven D.; Sun, Longchang; Liu, Xiao; Liu, Weijun; Yang, Jing; Ning, Baiqi

    2015-11-01

    The first no-gap OH airglow all-sky imager network was established in northern China in February 2012. The network is composed of six all-sky airglow imagers that make observations of OH airglow gravity waves and cover an area of about 2000 km east and west and about 1400 km south and north. An unusual outbreak of Concentric Gravity Wave (CGW) events were observed by the network nearly every night during the first half of August 2013. These events were coincidentally observed by satellite sensors from Fengyun-2 (FY-2), Atmospheric Infrared Sounder (AIRS)/Aqua, and Visible Infrared Imaging Radiometer Suite (VIIRS)/Suomi National Polar-orbiting Partnership (NPP). Combination of the ground imager network with satellites provides multilevel observations of the CGWs from the stratosphere to the mesopause region. In this paper, two representative CGW events in August 2013 are studied in detail: first is the CGW on the night of 13 August 2013, likely launched by a single thunderstorm. The temporal and spatial analyses indicate that the CGW horizontal wavelengths follow freely propagating waves based on a GW dispersion relation within 300 km from the storm center. In contrast, the more distant observed gravity wave field exhibits a smaller horizontal wavelength of ~20 km, and our analysis strongly suggest this wave field represents a ducted wave. A second event, exhibiting multiple CGWs, was induced by two very strong thunderstorms on 9 August 2013. Multiscale waves with horizontal wavelengths ranging from less than 10 km to 200 km were observed.

  3. A fast SWIR imager for observations of transient features in OH airglow

    NASA Astrophysics Data System (ADS)

    Hannawald, Patrick; Schmidt, Carsten; Wüst, Sabine; Bittner, Michael

    2016-04-01

    Since December 2013 the new imaging system FAIM (Fast Airglow IMager) for the study of smaller-scale features (both in space and time) is in routine operation at the NDMC (Network for the Detection of Mesospheric Change) station at DLR (German Aerospace Center) in Oberpfaffenhofen (48.1° N, 11.3° E).Covering the brightest OH vibrational bands between 1 and 1.7 µm, this imaging system can acquire two frames per second. The field of view is approximately 55 km times 60 km at the mesopause heights. A mean spatial resolution of 200 m at a zenith angle of 45° and up to 120 m for zenith conditions are achieved. The observations show a large variety of atmospheric waves.This paper introduces the instrument and compares the FAIM data with spectrally resolved GRIPS (GRound-based Infrared P-branch Spectrometer) data. In addition, a case study of a breaking gravity wave event, which we assume to be associated with Kelvin-Helmholtz instabilities, is discussed.

  4. Imaging observations of lower thermospheric O(1S) and O2 airglow emissions from STS 9 - Implications of height variations

    NASA Technical Reports Server (NTRS)

    Swenson, G. R.; Mende, S. B.; Llewellyn, E. J.

    1989-01-01

    The lower thermospheric nightglow in the Southern Hemisphere was observed with the Atmospheric Emissions Photometric Imager during the Spacelab 1 mission in December, 1983. Observations of emission from O(1S) at 2972 and 5577A, O2 at 7620 A, OH near 6300 A, and the combined emission from the three upper states of O2 which lead to the Herzberg I and II and Chamberlain band emissions in B and near UV are discussed. The altitudes of peak emission heights are determined, showing that the peak heights are not constant with latitude. It is found that airglow heights varied with latitude by as much as 8 km. The observed airglow height pattern near the equator is similar to that of Wasser and Donahue (1979).

  5. Periodic waves in the lower thermosphere observed by OI630 nm airglow images

    NASA Astrophysics Data System (ADS)

    Paulino, I.; Medeiros, A. F.; Vadas, S. L.; Wrasse, C. M.; Takahashi, H.; Buriti, R. A.; Leite, D.; Filgueira, S.; Bageston, J. V.; Sobral, J. H. A.; Gobbi, D.

    2016-02-01

    Periodic wave structures in the thermosphere have been observed at São João do Cariri (geographic coordinates: 36.5° W, 7.4° S; geomagnetic coordinates based on IGRF model to 2015: 35.8° E, 0.48° N) from September 2000 to November 2010 using OI630.0 nm airglow images. During this period, which corresponds to almost one solar cycle, characteristics of 98 waves were studied. Similarities between the characteristics of these events and observations at other places around the world were noted, primarily the spectral parameters. The observed periods were mostly found between 10 and 35 min; horizontal wavelengths ranged from 100 to 200 km, and phase speed from 30 to 180 m s-1. These parameters indicated that some of the waves, presented here, are slightly faster than those observed previously at low and middle latitudes (Indonesia, Carib and Japan), indicating that the characteristics of these waves may change at different places. Most of observed waves have appeared during magnetically quiet nights, and the occurrence of those waves followed the solar activity. Another important characteristic is the quasi-monochromatic periodicity that distinguish them from the single-front medium-scale traveling ionospheric disturbances (MSTIDs) that have been observed previously over the Brazilian region. Moreover, most of the observed waves did not present a phase front parallel to the northeast-southwest direction, which is predicted by the Perkins instability process. It strongly suggests that most of these waves must have had different generation mechanisms from the Perkins instability, which have been pointed out as being a very important mechanism for the generation of MSTIDs in the lower thermosphere.

  6. WINDII atmospheric wave airglow imaging

    SciTech Connect

    Armstrong, W.T.; Hoppe, U.-P.; Solheim, B.H.; Shepherd, G.G.

    1996-12-31

    Preliminary WINDII nighttime airglow wave-imaging data in the UARS rolldown attitude has been analyzed with the goal to survey gravity waves near the upper boundary of the middle atmosphere. Wave analysis is performed on O[sub 2](0,0) emissions from a selected 1[sup 0] x 1[sup 0] oblique view of the airglow layer at approximately 95 km altitude, which has no direct earth background and only an atmospheric background which is optically thick for the 0[sub 2](0,0) emission. From a small data set, orbital imaging of atmospheric wave structures is demonstrated, with indication of large variations in wave activity across land and sea. Comparison ground-based imagery is discussed with respect to similarity of wave variations across land/sea boundaries and future orbital mosaic image construction.

  7. Concentric Gravity Waves over Northern China Observed by a No-Gap OH Airglow Imager Network and Satellites

    NASA Astrophysics Data System (ADS)

    Xu, J.; Li, Q.; Yue, J.; Hoffmann, L.; Straka, W. C.; Miller, S. D.; Yuan, W.; Liu, X.

    2015-12-01

    The first no-gap OH airglow all-sky imager network in the world was established in northern China in February 2012. The network is composed of 6 all-sky airglow imagers that make observations of OH airglow gravity waves and cover an area of about 2000 km east and west and about 1400 km south and north. A comparison of the observations in 2012, 2013, and 2014 are made, which shows that there were more strong thunderstorms take place in 2013 in the northern China and produce more Concentric Gravity Wave (CGW) events. Especially, a series of CGW events were observed by the network nearly every night during the first half of August 2013. These events were also observed by satellite sensors from FY-2, AIRS/Aqua, and VIIRS/Suomi NPP. Combination of the ground imager network with satellites provides multi-level observations of the CGWs from the stratosphere to the mesopause region. In this talk, two representative CGW events in August 2013 are studied in detail and movies of the two events are displayed. One is the CGW on the night of 13 August 2013, likely launched by a single thunderstorm. The temporal and spatial analyses indicate that the CGW horizontal wavelengths agree with the GW dispersion relation within 300 km from the storm center. A gravity wave with horizontal wavelength of about 20 km propagates horizontally to more than 800 km in the mesopause region, probably due to a ducting layer. Another CGW event was induced by two very strong thunderstorms on 09 August 2013. Multi-scale waves with horizontal wavelengths ranging from less than 10 km to 200 km were observed. Many ripples were found, probably due to the breaking of strong gravity waves with large relative OH intensity perturbations of 10%.

  8. Passive SWIR airglow illuminated imaging compared with NIR-visible for low-light nighttime observations

    NASA Astrophysics Data System (ADS)

    Dayton, David C.; Allen, Jeffery; Gonglewski, John D.; Nolasco, Rudolph; Myers, Michael; Burns, Dennis; Mons, Ishan; Maia, Francisco

    2011-05-01

    It is well known that luminance from photo-chemical reactions of hydroxyl ions in the upper atmosphere (~85 km altitude) produces a significant amount of night time radiation in the short wave infra-red (SWIR) band with wavelength between 0.9 and 1.7 μm. By examining images in an urban and a rural setting, we investigate the correlation between the appearances of passive dark of night images in the SWIR with NIR- visible. The experimental setup consists of two sensors, a NIR-visible CCD and an InGaAs array sensitive in the SWIR, both colocated on an AZ-EL mount, and both co-boresighted so that different viewing angles of the sky and terrestrial scenes are possible. By making corrections for focal length and pixel size, the visible and SWIR data can be compared. After taking several nights of data in the urban environment of Albuquerque, NM, the entire system was then re-located to a rural location on the island of Kauai in a rural setting with very low ambient light. It is shown that under most conditions the SWIR sensor produces significantly better imagery using the airglow illumination source.

  9. Lyman alpha airglow observations from SORCE SOLSTICE

    NASA Astrophysics Data System (ADS)

    Dolinar, E.; Snow, M.; Holsclaw, G.; Thomas, G. E.; Woods, T. N.

    2010-12-01

    The Solar Stellar Irradiance Comparison Experiment (SOLSTICE) instrument on board the Solar Radiation Climate Experiment (SORCE) spacecraft in low Earth orbit observes stars every orbit for in-flight calibration. It also observes several star-free regions of the sky near the wavelength of Lyman alpha to correct for airglow emission in the stellar measurements. Although the airglow measurements are only taken during the eclipse portion of the orbit, the look directions cover nearly the entire anti-sunward hemisphere. This seven-year record of Lyman alpha airglow observations (2003-2010) shows the response of the Hydrogen geocorona to changes in the solar Lyman alpha irradiance over the solar cycle.

  10. Gravity wave characteristics in the mesopause region revealed from OH airglow imager observations over Northern Colorado

    NASA Astrophysics Data System (ADS)

    Tang, Yihuan; Dou, Xiankang; Li, Tao; Nakamura, Takuji; Xue, Xianghui; Huang, Can; Manson, Alan; Meek, Chris; Thorsen, Denise; Avery, Susan

    2014-01-01

    Using 5 years of all-sky OH airglow imager data over Yucca Ridge Field Station, CO (40.7°N, 104.9°W), from September 2003 to September 2008, we extract and deduce quasi-monochromatic gravity wave (GW) characteristics in the mesopause region. The intrinsic periods are clustered between approximately 4 and 10 min, and many of them are unstable and evanescent. GW occurrence frequency exhibits a clear semiannual variation with equinoctial minima, which is likely related to the seasonal variation of background wind. The anomalous propagation direction in January 2006, with strong southward before major warming starting in 21 January and weak southward propagation afterward, was most likely affected by stratospheric sudden warming. The momentum fluxes show strongly anticorrelated with the tides, with ~180° out of phase in the zonal component. While in the meridional component, the easterly maximum occurred approximately 2-6 h after maximum easterly tidal wind. However, the anticorrelations are both weakest during the summer. The dissipating and breaking of small-scale and high-frequency GW's components could have a potential impact on the general circulation in the mesopause region.

  11. Statistical characteristics of gravity waves observed by an all-sky airglow imager at Maui, HI and Cerro Pachon, Chile

    NASA Astrophysics Data System (ADS)

    Cao, Bing; Liu, Alan Z.

    2016-07-01

    Many long-term observations, such as airglow imaging, have shown that gravity waves exist in the mesopause region most of the time. These waves deposit momentum and energy into the background atmosphere when dissipating, and thus exert strong influence to the atmosphere. In this study, we focus on (1) the climatology of gravity waves characteristics, (2) the intermittency of gravity wave momentum flux and (3) the duration/lifespan of gravity wave events. These properties have important implications for gravity wave parameterizations. This study is based on multi-year all sky OH airglow observations obtained at Maui, HI (20.7° N, 156.3° W) and the Andes Lidar Observatory in Chile (30.3° S, 70.7° W). The statistical distribution of intrinsic wave parameters and the momentum flux are analyzed. The probability density functions of gravity wave momentum flux and duration can be described by simple functions and are related to the gravity wave intermittency. The probability distributions of the two sites have some similarity but with noticeable differences, indicating different effects of the background flow and wave source on the gravity wave intermittency in the mesopause region.

  12. Seasonal hemispherical SWIR airglow imaging

    NASA Astrophysics Data System (ADS)

    Allen, Jeffrey; Dayton, David C.; Gonglewski, John D.; Myers, Michael M.; Nolasco, Rudolph

    2011-09-01

    Airglow luminescence in the SWIR region due to upper atmospheric recombination of solar excited molecules is a well accepted phenomenon. While the intensity appears broadly uniform over the whole sky hemisphere, we are interested in variations in four areas: 1) fine periodic features known as gravity waves, 2) broad patterns across the whole sky, 3) temporal variations in the hemispheric mean irradiance over the course of the night, and 4) long term seasonal variations in the mean irradiance. An experiment is described and results presented covering a full year of high resolution hemispheric SWIR irradiance images. An automated gimbal views 45 hemispheric positions, using 30 second durations, and repeats approximately every half hour through out the night. The gimbal holds co-mounted and bore-sighted visible and SWIR cameras. Measuring airglow with respect to spatial, temporal, and seasonal variations will facilitate understanding its behavior and possible benefits, such as night vision and predicting upper atmosphere turbulence. The measurements were performed in a tropical marine location on the island of Kauai Hi.

  13. Initial Observations from a Narrow-Field Ionospheric Airglow Imager at the Cerro Tololo Inter-American Observatory

    NASA Astrophysics Data System (ADS)

    Makela, J. J.; Miller, E. S.

    2006-12-01

    In August 2006, a miniaturized narrow-field ionospheric airglow imager was installed at the Cerro Tololo Inter- American Observatory (CTIO) east of La Serena, Chile (-29.9 N, 288.7 E geo; -16.46 N, 0.0388 E mag), in order to observe irregularities associated with equatorial spread-F. Two GPS L1 scintillation monitors were also installed to study the characteristics of the irregularities at the GPS Fresnel size. The imager looks north parallel to the Earth's magnetic field in the ionosphere towards the magnetic equator. By doing so, the imager can observe small-scale structure mapped along the magnetic field lines from the equatorial ionosphere to the local ionosphere. Initial observations include secondary instabilities, bifurcations, and kilometer-scale structure. Coordination with an all-sky imager near the CTIO magnetic conjugate point in Villa de Leyva, Colombia (5.57 N, 287.37 E geo; 17.79 N, -0.125 E mag), and the Jicamarca incoherent-scatter radar near Lima, Peru (-11.95 N, 283.13 E geo; 0.616 N, -5.39 E mag), are anticipated in the near future. In this way, we will be able to study the entire flux-tube geometry associated with the development of equatorial instabilities and investigate the relative roles of the equatorial and local, off-equatorial ionospheres in the severity of these scintillation-causing irregularities.

  14. Solar cycle variation of gravity waves observed in OH airglow

    NASA Astrophysics Data System (ADS)

    Gelinas, L. J.; Hecht, J. H.; Walterscheid, R. L.; Reid, I. M.; Woithe, J.; Vincent, R. A.

    2013-12-01

    Airglow imaging provides a unique means by which to study many wave-related phenomena in the 80 to 100 km altitude regime. Two-dimensional image observations reveal quasi-monochromatic disturbances associated with atmospheric gravity waves (AGWs) as well as small-scale instabilities, often called ripples. Image-averaged temperature and intensity measurements can be used to study the response of the airglow layer to tides and planetary waves, as well as monitor longer-term climatological variations. Here we present results of low and mid-latitude OH airglow observations beginning near solar max of solar cycle 23 and continuing through solar max of cycle 24. Aerospace imagers deployed at Alice Springs (23o42'S, 133o53'E) and Adelaide (34o55'S, 138o36'E) have been operating nearly continuously since ~2001. The imagers employ filters measuring OH Meinel (6, 2) and O2 Atmospheric (0, 1) band emission intensities and temperatures, as well as atmospheric gravity wave parameters. The Aerospace Corporation's Infrared Camera deployed at Maui, HI (20.7N,156.3W), collected more than 700 nights of airglow images from 2002-2005. The camera measures the OH Meinel (4,2) emission at 1.6 um using a 1 second exposure at a 3 second cadence, which allows the study of AGW and ripple features over very short temporal and spatial scales. The camera was relocated to Cerro Pachon, Chile (30.1 S, 70.8 W) and has been operating continuously since 2010. Temperature, intensity and gravity wave climatologies derived from the two Australian airglow imagers span a full solar cycle (solar max to solar max). Emission intensities have been calibrated using background stars, and temperatures have been calibrated with respect to TIMED/SABER temperatures, reducing the influence of instrument degradation on the solar cycle climatology. An automated wave detection algorithm is used to identify quasi monochromatic wave features in the airglow data, including wavelength, wave period and propagation

  15. Coordinated airglow observations between IMAP/VISI and a ground-based all-sky imager on concentric gravity wave in the mesopause

    NASA Astrophysics Data System (ADS)

    Perwitasari, S.; Sakanoi, T.; Yamazaki, A.; Otsuka, Y.; Hozumi, Y.; Akiya, Y.; Saito, A.; Shiokawa, K.; Kawamura, S.

    2015-11-01

    We present a study of concentric gravity waves (CGWs) event from the coordinated observation between Ionosphere, Mesosphere, upper Atmosphere, and Plasmasphere mapping (IMAP)/Visible and near-Infrared Spectral Imager (VISI), all-sky camera at Rikubetsu, Multi-functional Transport Satellite (MTSAT), Tropical Rainfall Measuring Mission, and MF radar at Wakkanai combined with Modern-Era Retrospective Analysis for Research and Application data. IMAP/VISI is the first space-based imager that capable of imaging the airglow in the mesosphere and lower thermosphere region in the nadir-looking direction. Therefore, it has a unique ability to observe a great extend of CGWs propagation. Arc-like shaped, part of CGWs pattern was observed around the mesopause (~95 km) in the O2 762 nm airglow emission obtained by IMAP/VISI at 1204 UT on 18 October 2012. Similar patterns were also observed by the all-sky imager at Rikubetsu (43.5°N, 143.8°E) in OI 557.7 nm and OH band airglow emissions from ~1100 to 1200 UT. Horizontal wavelengths of the observed small-scale gravity waves are ~50 km (OH band and OI 557.7 nm) and ~67 km (O2 762 nm). The source is suggested to be a deep convective activity over Honshu Island which likely was an enhanced convective activity related to a typhoon in the south of Japan. The data showed that the CGWs could propagate up to ~1400-1500 km horizontally from the source to the mesopause but not farther away. Using atmospheric temperature profiles obtained by Thermospheric Ionosphere Mesosphere Energetics Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry, we conclude that this long-distance propagation of the waves could be caused by thermal duct in the middle atmosphere. The arc-like shaped instead of full circle pattern points out that the wind filtering effect is significant for the particular direction of wave propagation.

  16. Gravity waves in mesopause region induced by thunderstorms over Northern China observed by a no-gap OH airglow imager network

    NASA Astrophysics Data System (ADS)

    Xu, Jiyao

    2016-07-01

    A no-gap OH airglow all-sky imager network was established in northern China in February 2012. The network is composed of 6 all-sky airglow imagers that make observations of OH airglow gravity waves and cover an area of about 2000 km east and west and about 1400 km south and north. A large number of gravity wave events in the mesopause region induced by thunderstorms were observed by the network during the past 4 years. A comparison of the observations in 2012, 2013, and 2014 are made, which shows that there were more strong thunderstorms take place in 2013 in the northern China and produce more Concentric Gravity Wave (CGW) events. Especially, a series of CGW events were observed by the network nearly every night during the first half of August 2013. These events were also observed by satellite sensors from FY-2, AIRS/Aqua, and VIIRS/Suomi NPP. Combination of the ground imager network with satellites provides multi-level observations of the CGWs from the stratosphere to the mesopause region. In this talk, two representative CGW events in August 2013 are studied in detail and movies of the two events are displayed. One is the CGW on the night of 13 August 2013, likely launched by a single thunderstorm. The temporal and spatial analyses indicate that the CGW horizontal wavelengths agree with the GW dispersion relation within 300 km from the storm center. A gravity wave with horizontal wavelength of about 20 km propagates horizontally to more than 800 km in the mesopause region, probably due to a ducting layer. Another CGW event was induced by two very strong thunderstorms on 09 August 2013. Multi-scale waves with horizontal wavelengths ranging from less than 10 km to 200 km were observed. Many ripples were found, probably due to the breaking of strong gravity waves with large relative OH intensity perturbations of 10%.

  17. The Michelson Interferometer for Airglow Dynamics Imaging (MIADI)

    NASA Astrophysics Data System (ADS)

    Langille, J.; Nakamura, T.; Ward, W. E.

    2009-05-01

    The Michelson Interferometer for Airglow Dynamics Imaging (MIADI) is a new implementation of the imaging field-widened Michelson interferometer concept which images airglow signatures in the mesopause region and simultaneously records wind and intensity images. The scientific purpose of this instrument is to provide unambiguous information on gravity waves since the background horizontal wind and irradiance variations will be simultaneously obtained. Calibration and characterization of instrument parameters has been completed at a field site in Shigaraki Japan and initial observations have been taken. Co-located alongside MIADI are the MU radar, Na Lidar and several All-Sky Imagers. Observation campaigns are ongoing to acquire simultaneous data sets from these instruments. In this paper, the calibration and characterization results will be summarized. The initial measurements of winds and intensity will be presented and the scientific goals of the current observing campaign outlined.

  18. Spatial relationship of nighttime medium-scale traveling ionospheric disturbances and F region field-aligned irregularities observed with two spaced all-sky airglow imagers and the middle and upper atmosphere radar

    NASA Astrophysics Data System (ADS)

    Otsuka, Y.; Shiokawa, K.; Ogawa, T.; Yokoyama, T.; Yamamoto, M.

    2009-05-01

    We report simultaneous observations of medium-scale traveling ionospheric disturbances (MSTIDs) and field-aligned irregularities (FAIs) in the F region using two all-sky airglow imagers and the middle and upper atmosphere (MU) radar. MSTIDs propagating southwestward were observed simultaneously in 630-nm airglow images over Sakata (39.0°N, 139.9°E) and Shigaraki (34.9°N, 136.1°E), Japan, on the night of 16 June 2004. By using all-sky images over both sites, we estimated the altitude of the airglow layer to be 260 km by the triangulation method. During the MSTID event, FAIs in the F region were observed by making multibeam measurements with the MU radar at Shigaraki. In order to investigate the spatial relationship between the MSTIDs and FAIs, the FAIs were mapped onto the 630-nm airglow layer (altitude, 260 km) along the geomagnetic field lines. We found that FAIs with an intense (weak) signal-to-noise ratio coincided with the airglow depletion (enhancement) caused by the MSTIDs. FAI velocity obtained from a combination of the Doppler velocities on the three radar beams oscillated in the northwest-southeast direction, with an amplitude of approximately 82 m/s. The FAI velocity was northwestward (southeastward) at the airglow depletion (enhancement). The directions of the FAI velocity were consistent with those of the E × B drifts caused by the polarized electric fields associated with the MSTIDs. The northeastward polarized electric field at the airglow depletion region strengthened the background eastward effective electric field and drove the gradient drift instability generating FAIs. This might be the reason why the FAIs preferred to occur at the airglow depletion region.

  19. Results from a high-speed imaging system for the observation of transient features in OH-Airglow with focus on small-scale structures

    NASA Astrophysics Data System (ADS)

    Hannawald, Patrick; Kazlova, Aliaksandra; Schmidt, Carsten; Wüst, Sabine; Bittner, Michael

    2016-04-01

    The OH-airglow layer in about 87 km altitude is suited to investigate atmospheric dynamics in a unique way, allowing continuous observations of the night-sky throughout the year. Especially, atmospheric gravity waves are prominent features in the data of airglow imaging systems. In the year 2014 the imaging system FAIM (Fast Airglow IMager) for the study of small-scale features (both in space and time) was operational at the NDMC (Network for the detection of mesospheric change) station Oberpfaffenhofen. The instrument covers many of the brightest OH vibrational bands between 1.0 μm and 1.7 μm and acquires images with a temporal resolution of 2 frames per second. It measures the night sky with an aperture angle of about 20° and a zenith angle of 45° oriented to the Southern Germany Alpine region. Hence, the field of view (FOV) is about 50 km times 60 km in the height of the mesopause (87 km) with a mean spatial resolution of about 200 m. With this resolution, the focus of the instrument is on small-scale wave structures ranging from about 1 km to 30 km and instability structures like so-called ripples or Kelvin-Helmholtz-Instabilities. Case studies will be presented showing dissipating gravity waves and the results of spectral analyses will give an overview of the prominent directions of propagation and the horizontal wavelengths within the year 2014. This work is funded by the Bavarian State Ministry of the Environment and Consumer Protection by grant no. TUS01UFS-67093. The project aims to analyse the influence of the Alpine region on the generation of atmospheric waves.

  20. TIMED GUVI and SEE Observations of Solar Irradiance Variations and the Terrestrial Airglow Response

    NASA Astrophysics Data System (ADS)

    Wolven, B.; Paxton, L.; Morrison, D.; Woods, T.

    2004-12-01

    Since the launch of the TIMED mission in 2001, the SEE and GUVI instruments have observed solar radiance changes during numerous solar flares, and measured their short-term impact on the terrestrial airglow, manifested as changes in both resonantly scattered and photoelectron excited emissions. The continuous coverage and higher time resolution of the GUVI airglow observations, in conjunction with the multispectral (5-color) image format, constitute a unique source of information on the time variation of the solar irradiance in different spectral regions. GUVI limb observations provide additional data on heating and composition changes in the thermosphere in response to these energy inputs. We examine changes in the observed airglow between quiet and flare conditions, and attempt to understand the differences between SEE measurements and the radiances inferred from GUVI airglow data.

  1. Tomographic imaging of airglow from airborne spectroscopic measurements.

    PubMed

    Anderson, D Scott; Swenson, Gary; Kamalabadi, Farzad; Liu, Alan

    2008-05-01

    A description is given of the methodology based on a single, aircraft-mounted spectroscopic imager to tomographically reconstruct airglow perturbations induced by atmospheric gravity waves. In this configuration, the imager passes under the airglow structure to gather multiple-angle views of the wave structure in a relatively short amount of time. Under the assumption that the airglow structure does not change significantly during the acquisition interval, the data can be tomographically inverted to estimate the 2D (horizontal-vertical) airglow structure. We develop an inversion strategy for this image formation task and illustrate its applicability by inverting time-sequential imaging data taken from different vantage points during the ALOHA-93 campaign to reconstruct atmospheric gravity wave structures. PMID:18449320

  2. Removing Milky Way from airglow images using principal component analysis

    NASA Astrophysics Data System (ADS)

    Li, Zhenhua; Liu, Alan; Sivjee, Gulamabas G.

    2014-04-01

    Airglow imaging is an effective way to obtain atmospheric gravity wave information in the airglow layers in the upper mesosphere and the lower thermosphere. Airglow images are often contaminated by the Milky Way emission. To extract gravity wave parameters correctly, the Milky Way must be removed. The paper demonstrates that principal component analysis (PCA) can effectively represent the dominant variation patterns of the intensity of airglow images that are associated with the slow moving Milky Way features. Subtracting this PCA reconstructed field reveals gravity waves that are otherwise overwhelmed by the strong spurious waves associated with the Milky Way. Numerical experiments show that nonstationary gravity waves with typical wave amplitudes and persistences are not affected by the PCA removal because the variances contributed by each wave event are much smaller than the ones in the principal components.

  3. First spaceborne observation of the entire concentric airglow structure caused by tropospheric disturbance

    NASA Astrophysics Data System (ADS)

    Akiya, Y.; Saito, A.; Sakanoi, T.; Hozumi, Y.; Yamazaki, A.; Otsuka, Y.; Nishioka, M.; Tsugawa, T.

    2014-10-01

    Spaceborne imagers are able to observe the airglow structures with wide field of views regardless of the tropospheric condition that limits the observational time of the ground-based imagers. Concentric wave structures of the O2 airglow in 762 nm wavelength were observed over North America on 1 June 2013 from the International Space Station. This was the first observation in which the entire image of the structure was captured from space, and its spatial scale size was determined to be 1200 km radius without assumptions. The apparent horizontal wavelength was 80 km, and the amplitude in the intensity was approximately 20% of the background intensity. The propagation velocity of the structure was derived as 125 ± 62 m/s and atmospheric gravity waves were estimated to be generated for 3.5 ± 1.7 h. Concentric structures observed in this event were interpreted to be generated by super cells that caused a tornado in its early phase.

  4. Imaging mesospheric winds using the Michelson interferometer for airglow dynamics imaging

    NASA Astrophysics Data System (ADS)

    Langille, Jeffery; Ward, William E.

    2016-07-01

    The first ground based images of mesospheric winds in airglow are presented and discussed in this paper. These were obtained with the Michelson Interferometer for Airglow Dynamics Imaging (MIADI)a ground based field widened Michelsoin interferometer designed to obtain two dimensional images of the line of sight Doppler wind and irradiance field in the mesosphere. The purpose of this instrument is to measure perturbations in line-of-sight wind and airglow irradiance associated with gravity waves. In its current configuration, the instrument observes an ~80 km x ~80 km region of the night sky in ~33 minutes using the O(1S) emission at 557.73 nm and the OH (6, 2) P1 (2) emission at 839.918 nm. The instrument was installed and tested at a field site outside Fredericton, NB (45.96 N, 66.65 W) during the summer of 2014. Successful measurements over a six hour period were obtained on July 31, 2014. Variations in the meridional and zonal wind were observed that are consistent with a semi-diurnal tide with an amplitude of ˜ 35 m/s. Small scale variations (< 10 m/s) were also observed that indicate the presence of gravity waves. In this paper, the instrument concept will be presented and the field measurements and their precision and accuracy discussed.

  5. The Michelson Interferometer for Airglow Dynamics Imaging: Instrument Description

    NASA Astrophysics Data System (ADS)

    Langille, Jeffery; Ward, William E.; Gault, William A.; Miller, Ian; Scott, Alan

    The Michelson Interferometer for Airglow Dynamics Imaging (MIADI) is a new implementation of the imaging field-widened Michelson interferometer concept. Airglow signatures in the mesopause region are imaged through the interferometer and wind and intensity images are simultaneously recorded. The field-of-view for this instrument is a 30 degree square region. This field will be divided into 100 bins (10 by 10) and measurements of intensity and line-of-sight wind taken for each bin. Two emissions (oxygen green line and hydroxyl) will be viewed simultaneously. The scientific purpose of this instrument is to provide unambiguous information on gravity waves since the background horizontal wind, and wind and irradiance variations will be simultaneously obtained. In the paper, the measurement principle and the characteristics of the instrument will be described and some initial results presented.

  6. Ionospheric imaging using merged ultraviolet airglow and radio occultation data

    NASA Astrophysics Data System (ADS)

    Stephan, Andrew W.; Budzien, Scott A.; Finn, Susanna C.; Cook, Timothy A.; Chakrabarti, Supriya; Powell, Steven P.; Psiaki, Mark L.

    2014-09-01

    The Limb-imaging Ionospheric and Thermospheric Extreme-ultraviolet Spectrograph (LITES) and GPS Radio Occultation and Ultraviolet Photometry-Colocated (GROUP-C) experiments are being considered for flight aboard the Space Test Program Houston 5 (STP-H5) experiment pallet to the International Space Station (ISS). LITES is a compact imaging spectrograph that makes one-dimensional images of atmospheric and ionospheric ultraviolet (60-140 nm) airglow above the limb of the Earth. The LITES optical design is advantageous in that it uses a toroidal grating as its lone optical surface to create these high-sensitivity images without the need for any moving parts. GROUP-C consists of two instruments: a nadir-viewing ultraviolet photometer that measures nighttime ionospheric airglow at 135.6 nm with unprecedented sensitivity, and a GPS receiver that measures ionospheric electron content and scintillation with the assistance of a novel antenna array designed for multipath mitigation. By flying together, these two experiments form an ionospheric observatory aboard the ISS that will provide new capability to study low- and mid-latitude ionospheric structures on a global scale. This paper presents the design and implementation of the LITES and GROUP-C experiments on the STP-H5 payload that will combine for the first time high-sensitivity in-track photometry with vertical spectrographic imagery of ionospheric airglow to create high-fidelity images of ionospheric structures. The addition of the GPS radio occultation measurement provides the unique opportunity to constrain, as well as cross-validate, the merged airglow measurements.

  7. Aerosol properties in Titan's upper atmosphere from UVIS airglow observations

    NASA Astrophysics Data System (ADS)

    Lavvas, Panayotis; Koskinen, Tommi; Royer, Emilie; Rannou, Pascal; West, Robert A.

    2015-11-01

    Multiple Cassini observations reveal that the abundant aerosol particles in Titan's atmosphere are formed at high altitudes, particularly in the thermosphere [1]. They subsequently fall towards the lower atmosphere, and in their path, their size, shape, and population change in reflection to the variable atmospheric conditions.Although multiple observations can help us retrieve information for the aerosol properties in the lower atmosphere [2], we have limited knowledge for their properties in the altitude range between their formation region in the thermosphere, and the upper region of the main haze layer. UVIS is one of a few instruments that can probe this part of the atmosphere and allow for the retrieval of the aerosol properties.Here we analyze observations of atmospheric airglow that demonstrate the signature of N2 emissions and light scattering from aerosol particles, at different altitudes above 500 km [3]. We fit these observations with a combined model of N2 airglow [4] and atmospheric scattering by gases and aerosols that allows us to separate the pure scattering component and retrieve the aerosol size (distribution) and density. We particularly focus on observations from the T32 flyby that probed high southern latitudes in 2007 and combine good altitude resolution with high signal to noise ratio. We combine these with observations at different phase angles and observing geometry conditions (nadir vs. limb) in order to set better constraints on the aerosol properties.Our preliminary results demonstrate an increase in the average particle size with decreasing altitude in the atmosphere, from about 10 nm at 800 km to ~50 nm at 500 km, and an extinction profile at 185 nm wavelength, similar to the profile derive from UVIS occultation measurements at lower latitudes [5].[1] Lavvas et al. 2013. PNAS, doi/10.1073/pnas.1217059110, and references therein.[2] Tomasko et al. 2008, PSS, 56, p.669; Bellucci et al. 2009, Icarus 201, p.198[3] Ajello et al. 2008, GRL

  8. Hemispheric asymmetry in transition from equatorial plasma bubble to blob as deduced from 630.0 nm airglow observations at low latitudes

    NASA Astrophysics Data System (ADS)

    Park, Jaeheung; Martinis, Carlos R.; Lühr, Hermann; Pfaff, Robert F.; Kwak, Young-Sil

    2016-01-01

    Transitions from depletions to enhancements of 630.0 nm nighttime airglow have been observed at Arecibo. Numerical simulations by Krall et al. (2009) predicted that they should occur only in one hemisphere, which has not yet been confirmed observationally. In this study we investigate the hemispheric conjugacy of the depletion-to-enhancement transition using multiple instruments. We focus on one event observed in the American longitude sector on 22 December 2014: 630.0 nm airglow depletions evolved into enhancements in the Northern Hemisphere while the evolution did not occur in the conjugate location in the Southern Hemisphere. Concurrent plasma density measured by low Earth orbit (LEO) satellites and 777.4 nm airglow images support that the depletions and enhancements of 630.0 nm nighttime airglow reflect plasma density decreases and increases (blobs), respectively. Characteristics of the airglow depletions, in the context of the LEO satellite data, further suggest that the plasma density depletion deduced from the airglow data represents equatorial plasma bubbles (EPBs) rather than medium-scale traveling ionospheric disturbances from midlatitudes. Hence, the event in this study can be interpreted as EPB-to-blob transition.

  9. Thermospheric aurora and airglow

    SciTech Connect

    Meier, R.R.

    1987-04-01

    New information added in the years between 1983 and 1986 to the understanding of the physics and chemistry responsible for the production of aurora and airglow emissions is presented. On auroras, the bulk of new information comes from the information obtained from satellite-based imaging (by DE1) and spectroscopy, rocket-based observations of bremsstrahlung from electrons precipitating in the auroral zone, and measurements of metastable ion species. On airglow, the DE1 photometric experiment has provided the opportunity of studying the geocorona on a global scale. A geotail was detected in the antisolar direction, confirming earlier observations. 123 references.

  10. Rocket observations of the ultraviolet airglow during morning twilight

    NASA Technical Reports Server (NTRS)

    Cebula, R. P.; Feldman, P. D.

    1984-01-01

    Rocket-borne (Astrobee) UV measurements were made of the terrestrial airglow at morning twilight from 82 and 90 deg zenith angles at altitudes of 90 and 246 km in September 1979. Data were acquired on the NO gamma and delta bands, the 2470 A O II, 1356 A and the 1304 A O I lines, the Lyman-Berge-Hopfield N2 and the Herzberg 02 lines. The zodiacal contribution was substracted to obtain pure airglow data. Spectral analyses supported a larger nighttime decrease of N(4S) than for NO, the latter being in diffusive equilibrium above 190 km altitude. The NO gamma band was directly related to the thermospheric N(4S) contribution, the latter having a density of 2-8 million/cu cm at 200 km. Finally, self-consistent photoionization and photoelectron impact ionization models were derived for the atomic and ionic oxygen emissions.

  11. Imaging and modeling the ionospheric airglow response over Hawaii to the tsunami generated by the Tohoku earthquake of 11 March 2011

    NASA Astrophysics Data System (ADS)

    Makela, J. J.; Lognonné, P.; Hébert, H.; Gehrels, T.; Rolland, L.; Allgeyer, S.; Kherani, A.; Occhipinti, G.; Astafyeva, E.; Coïsson, P.; Loevenbruck, A.; Clévédé, E.; Kelley, M. C.; Lamouroux, J.

    2011-07-01

    Although only centimeters in amplitude over the open ocean, tsunamis can generate appreciable wave amplitudes in the upper atmosphere, including the naturally occurring chemiluminescent airglow layers, due to the exponential decrease in density with altitude. Here, we present the first observation of the airglow tsunami signature, resulting from the 11 March 2011 Tohoku earthquake off the eastern coast of Japan. These images are taken using a wide-angle camera system located at the top of the Haleakala Volcano on Maui, Hawaii. They are correlated with GPS measurements of the total electron content from Hawaii GPS stations and the Jason-1 satellite. We find waves propagating in the airglow layer from the direction of the earthquake epicenter with a velocity that matches that of the ocean tsunami. The first ionospheric signature precedes the modeled ocean tsunami generated by the main shock by approximately one hour. These results demonstrate the utility of monitoring the Earth's airglow layers for tsunami detection and early warning.

  12. Space-based imaging of nighttime medium-scale traveling ionospheric disturbances using FORMOSAT-2/ISUAL 630.0 nm airglow observations

    NASA Astrophysics Data System (ADS)

    Rajesh, P. K.; Liu, J. Y.; Lin, C. H.; Chen, A. B.; Hsu, R. R.; Chen, C. H.; Huba, J. D.

    2016-05-01

    This paper reports the results of space-based imaging of nighttime medium-scale traveling ionospheric disturbances (MSTIDs) in 630.0 nm emission by Imager of Sprites and Upper Atmospheric Lightnings (ISUAL), on board FORMOSAT-2 satellite. The limb integrated measurements, after removing background, reveal multiple bands of intensity perturbation when projected to a horizontal plane corresponding to the altitude of peak emission, with distinct southwest to northeast orientation in the Southern Hemisphere. Simulations are carried out by artificially introducing MSTID fluctuations in model electron density to confirm if the MSTID could be identified in the ISUAL-viewing geometry. The ISUAL observations in year 2007 are further used to investigate the MSTID features as well as occurrence characteristics in the Southern Hemisphere, most of which are over the ocean where no ground-based observations are available. The preliminary statistics shows more MSTID occurrence in solstices with peak in June-July months. Majority of the MSTID perturbations have wavelength in the range 150-300 km, and the wavefronts are aligned at about 30°-50° from the east-west plane. The statistic results of the orientation of wavefronts indicate that Es layer instability might be important in the MSTID generation.

  13. Catalog of data summary of airglow observations obtained at Haleakala, Hawaii

    NASA Technical Reports Server (NTRS)

    Steiger, W. R.; Smith, L. L.

    1974-01-01

    The airglow studies were initiated in July 1961 in response to the discovery of unusual phenomena in the tropical airglow as observed from Algeria. Hawaii, being the southern-most area in the United States and within the tropics, and possessing high mountains with frequent clear skies well isolated from the contaminating light and dust of civilization, appeared to be an ideal location for establishing a tropical airglow station. The University of Hawaii was already developing the Mees Solar Laboratory on Haleakala on the island of Maui, so that the addition of a night sky observatory was a natural development. The collection of data covers a span of about seven and one-half years, including the minimum of the solar cycle in 1963 and just getting into the next maximum in 1968-69. It was unfortunate that financial limitations did not permit the continuation of the observations through one complete solar cycle.

  14. Limb Viewing Hyper Spectral Imager (LiVHySI) for airglow measurements onboard YOUTHSAT-1

    NASA Astrophysics Data System (ADS)

    Bisht, R. S.; Hait, A. K.; Babu, P. N.; Sarkar, S. S.; Benerji, A.; Biswas, A.; Saji, A. K.; Samudraiah, D. R. M.; Kirankumar, A. S.; Pant, T. K.; Parimalarangan, T.

    2014-08-01

    The Limb Viewing Hyper Spectral Imager (LiVHySI) is one of the Indian payloads onboard YOUTHSAT (inclination 98.73°, apogee 817 km) launched in April, 2011. The Hyper-spectral imager has been operated in Earth’s limb viewing mode to measure airglow emissions in the spectral range 550-900 nm, from terrestrial upper atmosphere (i.e. 80 km altitude and above) with a line-of-sight range of about 3200 km. The altitude coverage is about 500 km with command selectable lowest altitude. This imaging spectrometer employs a Linearly Variable Filter (LVF) to generate the spectrum and an Active Pixel Sensor (APS) area array of 256 × 512 pixels, placed in close proximity of the LVF as detector. The spectral sampling is done at 1.06 nm interval. The optics used is an eight element f/2 telecentric lens system with 80 mm effective focal length. The detector is aligned with respect to the LVF such that its 512 pixel dimension covers the spectral range. The radiometric sensitivity of the imager is about 20 Rayleigh at noise floor through the signal integration for 10 s at wavelength 630 nm. The imager is being operated during the eclipsed portion of satellite orbits. The integration in the time/spatial domain could be chosen depending upon the season, solar and geomagnetic activity and/or specific target area. This paper primarily aims at describing LiVHySI, its in-orbit operations, quality, potential of the data and its first observations. The images reveal the thermospheric airglow at 630 nm to be the most prominent. These first LiVHySI observations carried out on the night of 21st April, 2011 are presented here, while the variability exhibited by the thermospheric nightglow at O(1D) 630 nm has been described in detail.

  15. Measurement of mesospheric winds using the Michelson Interferometer for Airglow Dynamics Imaging (MIADI)

    NASA Astrophysics Data System (ADS)

    Langille, Jeffery; Ward, William E.; Nakamura, Takuji

    MIADI images the wind and irradiance fields present in mesospheric airglow signatures using a new implementation of the field widened Michelson technique. The system is unique in its ability to image the mean wind and irradiance as well as the perturbation quantities, allowing for unambiguous gravity wave parameters to be derived using a single optical element. MIADI was installed and tested at the MU radar field site in Shigaraki Japan in 2009. Several nights of observations have been obtained and the initial analysis has been completed. In this presentation, the instrument technique, calibration process and installation/testing will be described and the analysis of the initial wind and irradiance measurements will be presented.

  16. Observations of thunderstorm-related 630 nm airglow depletions

    NASA Astrophysics Data System (ADS)

    Kendall, E. A.; Bhatt, A.

    2015-12-01

    The Midlatitude All-sky imaging Network for Geophysical Observations (MANGO) is an NSF-funded network of 630 nm all-sky imagers in the continental United States. MANGO will be used to observe the generation, propagation, and dissipation of medium and large-scale wave activity in the subauroral, mid and low-latitude thermosphere. This network is actively being deployed and will ultimately consist of nine all-sky imagers. These imagers form a network providing continuous coverage over the western United States, including California, Oregon, Washington, Utah, Arizona and Texas extending south into Mexico. This network sees high levels of both medium and large scale wave activity. Apart from the widely reported northeast to southwest propagating wave fronts resulting from the so called Perkins mechanism, this network observes wave fronts propagating to the west, north and northeast. At least three of these anomalous events have been associated with thunderstorm activity. Imager data has been correlated with both GPS data and data from the AIRS (Atmospheric Infrared Sounder) instrument on board NASA's Earth Observing System Aqua satellite. We will present a comprehensive analysis of these events and discuss the potential thunderstorm source mechanism.

  17. Statistical Comparison of Gravity Wave Characteristics Obtained from Airglow All-Sky Observation at Mt. Bohyun, Korea and Shigaraki, Japan

    NASA Astrophysics Data System (ADS)

    Yang, Tae-Yong; Kwak, Young-Sil; Kim, Yong-Ha

    2015-12-01

    Previously, all-sky airglow images observed at Shigaraki (34.9° N, 136.1° E), Japan, during 2004 and 2005 were analyzed in relation to those observed at Mt. Bohyun (36.2° N, 128.9° E) for a comparison of their gravity wave characteristics (Kim et al. 2010). By applying the same selection criteria of waves and cloud coverages as in the case of Mt. Bohyun all-sky images, we derived apparent wavelengths, periods, phase velocities, and monthly occurrence rates of gravity waves at Shigaraki in this study. The distributions of wavelengths, periods, and speeds derived for Shigaraki were found to be roughly similar to those for Mt. Bohyun. However, the overall occurrence rates of gravity waves at Shigaraki were 36% and 34% for OI 557.7 nm and OH Meinel band airglow layers, respectively, which were significantly higher than those at Mt. Bohyun. The monthly occurrence rates did not show minima near equinox months, unlike those for Mt. Bohyun. Furthermore, the seasonal preferential directions that were clearly apparent for Mt. Bohyun were not seen in the wave propagation trends for Shigaraki. These differences between the two sites imply different origins of the gravity waves near the Korean peninsula and the Japanese islands. The gravity waves over the Japanese islands may originate from sources at various altitudes; therefore, wind filtering may not be effective in causing any seasonal preferential directions in the waves in the airglow layers. Our analysis of the Shigaraki data supports recent theoretical studies, according to which gravity waves can be generated from in situ sources, such as mesosphere wind shear or secondary wave formation, in the mesosphere.

  18. Optical imaging of airglow structure in equatorial plasma bubbles at radio scintillation scales

    NASA Astrophysics Data System (ADS)

    Holmes, J. M.; Pedersen, T.; Parris, R. T.; Stephens, B.; Caton, R. G.; Dao, E. V.; Kratochvil, S.; Morton, Y.; Xu, D.; Jiao, Y.; Taylor, S.; Carrano, C. S.

    2015-12-01

    Imagery of optical emissions from F-region plasma is one of the few means available todetermine plasma density structure in two dimensions. However, the smallest spatial scalesobservable with this technique are typically limited not by magnification of the lens or resolutionof the detector but rather by the optical throughput of the system, which drives the integrationtime, which in turn causes smearing of the features that are typically moving at speeds of 100m/s or more. In this paper we present high spatio-temporal imagery of equatorial plasma bubbles(EPBs) from an imaging system called the Large Aperture Ionospheric Structure Imager(LAISI), which was specifically designed to capture short-integration, high-resolution images ofF-region recombination airglow at λ557.7 nm. The imager features 8-inch diameter entranceoptics comprised of a unique F/0.87 lens, combined with a monolithic 8-inch diameterinterference filter and a 2x2-inch CCD detector. The LAISI field of view is approximately 30degrees. Filtered all-sky images at common airglow wavelengths are combined with magneticfield-aligned LAISI images, GNSS scintillation, and VHF scintillation data obtained atAscension Island (7.98S, 14.41W geographic). A custom-built, multi-constellation GNSS datacollection system was employed that sampled GPS L1, L2C, L5, GLONASS L1 and L2, BeidouB1, and Galileo E1 and E5a signals. Sophisticated processing software was able to maintainlock of all signals during strong scintillation, providing unprecedented spatial observability ofL band scintillation. The smallest-resolvable scale sizes above the noise floor in the EPBs, as viewed byLAISI, are illustrated for integration times of 1, 5 and 10 seconds, with concurrentzonal irregularity drift speeds from both spaced-receiver VHF measurements and single-stationGNSS measurements of S4 and σφ. These observable optical scale sizes are placed in thecontext of those that give rise to radio scintillation in VHF and L band signals.

  19. The O I 135.6 nm airglow observations of the midlatitude summer nighttime anomaly by TIMED/GUVI

    NASA Astrophysics Data System (ADS)

    Hsu, M. L.; Lin, C. H.; Hsu, R. R.; Liu, J. Y.; Paxton, L. J.; Su, H. T.; Tsai, H. F.; Rajesh, P. K.; Chen, C. H.

    2011-07-01

    This study presents the O I 135.6 nm airglow observation of the middle-latitude electron density enhancement during local summer nighttime by Global Ultraviolet Imager (GUVI) on board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) spacecraft. The nighttime density enhancement at magnetic middle latitudes in the Southern Hemisphere, known as the Weddell Sea Anomaly (WSA), had been studied by using multipoint observations, and a similar anomalous nighttime enhancement was also found in the Northern Hemisphere recently. The resemblance of both anomalies at magnetic middle latitudes in the Northern and Southern Hemispheres suggests that they should be categorized as the midlatitude summer nighttime anomaly (MSNA). To further explore the three-dimensional structure of the MSNA and its day-to-day variation, the two-dimensional global radiance maps and the vertical electron density profiles derived from disk and limb scans of the TIMED/GUVI 135.6 nm airglow observations are utilized in this study. These global observations show that the northern MSNA mainly occurs in Asia, Europe, and the North Atlantic Ocean regions, while the southern MSNA occurs in the South America-Antarctica region, near the WSA region. The GUVI day-to-day observations in 2006 further illustrate that the southern MSNA appears nightly in January-February and November-December, while the northern MSNA appears in 36 out of 41 total observation nights in May-June.

  20. Equatorial planetary waves in the mesosphere observed by airglow periodic oscillations

    NASA Astrophysics Data System (ADS)

    Buriti, R. A.; Takahashi, H.; Lima, L. M.; Medeiros, A. F.

    Planetary scale waves in the equatorial upper mesosphere were studied by measuring the airglow OI557.7 nm, O 2b(0,1) and OH(6,2) emission intensities and OH rotational temperature at São João do Cariri (7.4°S; 36.5°W). From four years of data, 1998-2001, periodic oscillations of the airglow emissions were analyzed using the Lomb-Scargle spectral analysis. An oscillation of 3-4 days was frequently observed, which might be ultra-fast Kelvin waves. No seasonal dependency of the wave activity was found. On some occasions we found a quasi-5-day oscillation with a phase difference between the emissions, suggesting an upward energy flow. This is interpreted as a normal mode Rossby wave.

  1. Characterization of exceptionally strong mesospheric wave events using all-sky and zenith airglow observations

    NASA Astrophysics Data System (ADS)

    Smith, Steven M.; Scheer, Jürgen; Reisin, Esteban R.; Baumgardner, Jeffrey; Mendillo, Michael

    2006-09-01

    Two unusually clear mesospheric gravity wave events were observed by the Boston University all-sky imager and the Argentine airglow spectrometer on two consecutive nights at the El Leoncito Observatory, Argentina (31.8°S, 69.3°W), during August 2001. Both events exhibited brightness amplitudes an order of magnitude above typical values. The first event had the appearance of a large-amplitude (>60% in OH(6-2), 22% in O2, and 37% in O(1S) emissions (peak to peak), compared to 1-5% typically), upward propagating gravity wave with pronounced nonlinear behavior. The waves also showed noticeably curved wavefronts, indicating that they had originated from a relatively small source region within ˜180 km of El Leoncito. Estimates of the vertical flux of horizontal energy and momentum for the wave event in the OH and O2 emissions were very large compared to typical values, and they also indicated a high degree of flux divergence over the nominal 8 km altitude between the two layers. The second event occurred on the following night and exhibited a frontal morphology and behavior consistent with an internal ducted gravity wave showing nonlinear behavior akin to a mesospheric bore. The disturbance also had several interesting characteristics; in particular, the propagation speed decreased during its passage across the sky. In addition, a strong vertical temperature gradient due to the semidiurnal tide appeared to influence the occurrence of the bore event.

  2. Tidal influence on O(1S) airglow emission rate distributions at the geographic equator as observed by WINDII

    NASA Technical Reports Server (NTRS)

    Shephere, G. G.; Mclandress, C.; Solheim, B. H.

    1995-01-01

    WINDII, the Wind Imaging Interferometer on the Upper Atmosphere Research Satellite, observes winds, temperatures and emission rates in the upper mesosphere and thermosphere. In this paper we report on nighttime observations of the vertical distribution of the O(1S) 557.7 nm emission near the geographic equator for March/April, 1993. The airglow volume emission rate distribution is found to be strongly dependent on local time. Beginning at dusk, an intense airglow emission layer descends from a mean altitude of 95 km, reaching 89 km by midnight after which the emission rapidly decays. Shortly after midnight it reappears weakly at a higher altitude and remains at this level as the emission rate gradually increases towards dawn. This strong local time dependence leads us to conclude that the effect is tidally driven. Comparison with the Forbes (1982a,b) model suggest that total density perturbations and changes in the atomic oxygen mixing ratio may the cause of the changes in emission rate distribution between dusk and midnight. The reappearance of the emission after midnight may be caused by downward winds bringing oxygen-rich air from above.

  3. Observations of non-migrating tides and ionospheric perturbations of O(1D) airglow by ISUAL instrument

    NASA Astrophysics Data System (ADS)

    Nee, Jan B.

    2014-08-01

    In this paper, we present the spatial variations of O(1D) airglow observed by the ISUAL (Imager of Sprites and Upper Atmospheric Lightning) instrument on board the FORMOSAT-2 satellite. With a CCD camera and a 630 nm filter, ISUAL can measure global atmospheric emissions lying between the heights of 80 and 300 km. In days of 3-6 September 2008 and 25-27 February 2009, ISUAL has measured the emissions of O(1D) airglow with results showing strong longitudinal peak-3 and peak-4 structures. The Lomb-Scargle analyses for these two cases show periods of longitudes of 120° and 90° supporting the DE2 and DE3 non-migrating tides. The 630 nm emissions are enhanced in equatorial regions and are lying along the equator. Over Africa its intensity can sometimes increase up to 80% relative to other longitudes. The perturbation is so strong that non-migrating tides are erased. A case of bimodal distribution with strong emissions at latitudes in equator and mid-latitude in geographic coordinates was observed.

  4. GUVI observations of the airglow response to solar flares: Results from the CAWSES campaign period

    NASA Astrophysics Data System (ADS)

    Wolven, B. C.; Paxton, L. J.; Morrison, D.

    2006-05-01

    GUVI limb and disk observations of oxygen and nitrogen airglow emissions show strong variability during solar events; both the intensity and the altitude of peak limb emission vary in response to the brightened and hardened solar spectrum. We present the observed response, and compare it to model predictions generated using a flare-type solar input spectrum. We examine the difference in atmospheric response to consecutive flare events, owing to the modification of thermospheric density and composition by the initial flare and subsequent geomagnetic disturbances.

  5. An atlas of low latitude 6300A (01) night airglow from OGO-4 observations

    NASA Technical Reports Server (NTRS)

    Reed, E. I.; Fowler, W. B.; Blamont, J. E.

    1972-01-01

    The atomic oxygen emission line at 6300 A, measured in the nadir direction by a photometer on the polar orbiting satellite OGO-4, was plotted between 40 deg N and 40 deg S latitude on a series of maps for the moon-free periods between 30 August 1967 and 10 January 1968 The longitudinal and local time variations which occur during the northern fall-winter season are indicated. The northern tropical arc is more widespread while the southern arc is not present at all longitudes. The conditions under which the observations were made are described, and four airglow maps were selected to show the local time variations.

  6. A novel approach for the extraction of cloud motion vectors using airglow imager measurements

    NASA Astrophysics Data System (ADS)

    Satheesh Kumar, S.; Narayana Rao, T.; Taori, A.

    2015-09-01

    The paper explores the possibility of implementing an advanced photogrammetric technique, generally employed for satellite measurements, on airglow imager, a ground-based remote sensing instrument primarily used for upper atmospheric studies, measurements of clouds for the extraction of cloud motion vectors (CMVs). The major steps involved in the algorithm remain the same, including image processing for better visualization of target elements and noise removal, identification of target cloud, setting a proper search window for target cloud tracking, estimation of cloud height, and employing 2-D cross-correlation to estimate the CMVs. Nevertheless, the implementation strategy at each step differs from that of satellite, mainly to suit airglow imager measurements. For instance, climatology of horizontal winds at the measured site has been used to fix the search window for target cloud tracking. The cloud height is estimated very accurately, as required by the algorithm, using simultaneous collocated lidar measurements. High-resolution, both in space and time (4 min), cloud imageries are employed to minimize the errors in retrieved CMVs. The derived winds are evaluated against MST radar-derived winds by considering it as a reference. A very good correspondence is seen between these two wind measurements, both showing similar wind variation. The agreement is also found to be good in both the zonal and meridional wind velocities with RMSEs < 2.4 m s-1. Finally, the strengths and limitations of the algorithm are discussed, with possible solutions, wherever required.

  7. Observations of airglow during injections of exhaust streams of ``Progress'' orbital maneuvering subsystem

    NASA Astrophysics Data System (ADS)

    Beletsky, Alexandr; Mikhalev, Alexander; Khakhinov, Vitaly; Lebedev, Valentin

    Observations of airglow during injections of exhaust streams of “Progress” orbital maneuvering subsystem A. Mikhalev, V. Khakhinov, A. Beletsky, V. Lebedev Institute of Solar-Terrestrial Physics of Siberian Branch of Russian Academy of Sciences (ISTP SB RAS) 664033, Lermontov str. 126a, p/o Box 291, Irkutsk, Russia ABSTRACT The effect of increasing the intensity of airglow emissions associated with spacecraft engines exhaust to the atmosphere is well-known. We carried out the "Radar-Progress" active space experiment for studying the ionosphere on April 17 2013. The exhaust products of orbital maneuvering subsystem engines of transport spacecraft “Progress” were used as a source of ionosphere disturbances. The engines run from 13:24:37 to 13:24:46 UT. The "Progress" orbit altitude was 412 km. We carried out observations of nightglow in the several spectral lines. The all-sky camera was used for obtaining spatial distribution of the 630 nm emission intensity. An increase in the emission intensity in the area of "Progress" track was observed after starting the engines. According to preliminary estimates, the rate of the glow expansion at the orbit altitude during first 60 seconds after the start was ~ 7 km/c along the orbit and ~ 3.5 km/s across the orbit. The observed glow area reached the largest size of ~ 350 km along the orbit and ~ 250 km across the orbit 120-150 s after start. The study has been supported by the grant 13-05-00456-a and 13-02-00957-a of the Russian Foundation for Basic Research and RF President Grant of Public Support for RF Leading Scientific Schools (NSh-2942.2014.5).

  8. Mesopause region wind, temperature and airglow irradiance above Eureka, Nunavut

    NASA Astrophysics Data System (ADS)

    Kristoffersen, Samuel; Ward, William E.; Vail, Christopher; Shepherd, Marianna

    2016-07-01

    The PEARL All Sky Imager (PASI, airglow images), the Spectral Airglow Temperature Imager (SATI, airglow irradiance and temperature) and the E-Region Wind Interferometer II (ERWIN2, wind, airglow irradiance and temperature) are co-located at the Polar Environment Atmospheric Research Laboratory (PEARL)in Eureka, Nunavut (80 N, 86 W). These instruments view the wind, temperature and airglow irradiance of hydroxyl (all three) O2 (ERWIN2 and SATI), sodium (PASI), and oxygen green line (PASI and ERWIN2). The viewing locations and specific emissions of the various instruments differ. Nevertheless, the co-location of these instruments provides an excellent opportunity for case studies of specific events and for intercomparison between the different techniques. In this paper we discuss the approach we are using to combine observations from the different instruments. Case studies show that at times the various instruments are in good agreement but at other times they differ. Of particular interest are situations where gravity wave signatures are evident for an extended period of time and one such situation is presented. The discussion includes consideration of the filtering effect of viewing through airglow layers and the extent to which wind, airglow and temperature variations can be associated with the same gravity wave.

  9. Seasonal dependence of MSTIDs obtained from 630.0 nm airglow imaging at Arecibo

    NASA Astrophysics Data System (ADS)

    Martinis, C.; Baumgardner, J.; Wroten, J.; Mendillo, M.

    2010-06-01

    All-sky imaging data of 630.0 nm airglow emissions are used to study the seasonal and solar activity dependence of medium-scale traveling ionospheric disturbances (MSTIDs) over Arecibo, Puerto Rico (18.3° N, 66.7° W, 28° N mag lat). MSTIDs are typical F-region signatures at midlatitudes, yet limited statistical results in the American sector hindered the progress in our understanding of these dynamical structures. This study compiles data from 2002 to 2007 and shows for the first time that optically-determined MSTIDs at Arecibo present a semiannual pattern with peak occurrence at both solstices. In the Japanese longitude sector, a similar pattern has been found, but one with a main peak during local summer. This paper explains the high occurrence rate during local winter at Arecibo via E-layer/F-layer coupling and inter-hemispheric coupling, thus accounting for a consistent morphology between the two longitude sectors.

  10. Helium 584 Å and H Lyman-α Airglow in Giant Planetary Atmospheres: Modeling, Observations, and Implications

    NASA Astrophysics Data System (ADS)

    Parkinson, Christopher; Esposito, Larry W.

    2016-07-01

    The atmosphere of the outer planets is mainly composed of H2 and neutral atomic helium. The study of He 584 Å and H Lyman-α brightnesses is interesting as the EUV and FUV (Extreme and Far Ultraviolet) planetary airglow have the potential to yield useful information about mixing and other important parameters in their thermospheres. Time variation, asymmetries, and polar enhancement of the airglow are also possible and analysis of the public archived NASA mission data sets (i.e. Voyager and Cassini) can help solve some of the outstanding problems associated with these phenomena. The comparison of observations with results from sophisticated photochemical and radiative transfer models can also help ameliorate unexplained differences in the dynamical processes operating within planetary upper atmospheres. Powerful analysis techniques allow us to extract information on atmospheric mixing, temperatures, and temporal changes due to the solar and seasonal cycles from the variations in distribution and intensity of airglow emissions that result. The presentation will discuss the implications of interpretations from comparison of modeling and observations in giant planetary atmospheres.

  11. Apollo 16 far ultraviolet imagery of the polar auroras, tropical airglow belts, and general airglow

    NASA Technical Reports Server (NTRS)

    Carruthers, G. R.; Page, T.

    1976-01-01

    Far-ultraviolet imagery of the earth in the wavelength ranges from 1050 to 1600 A and from 1250 to 1600 A was obtained from the lunar surface during the Apollo 16 mission on Apr. 21, 1972. The images have an angular resolution of about 2 arcmin (230-km linear resolution) and have been quantitatively analyzed to obtain absolute intensities and spatial distributions of the polar auroras (both wavelength ranges), the day and night airglow, and tropical airglow belts (1250-A to 1600-A wavelength range). The observations are consistent with previous results obtained from the OGO-4 spacecraft, but they have also provided details on the spatial distributions of the various emissions over an entire hemisphere at a single time. A general night airglow, at least in the Northern Hemisphere, is indicated.

  12. Kilometer-scale Structure in HF-induced Airglow at the HAARP Facility

    NASA Astrophysics Data System (ADS)

    Kendall, E.

    2008-12-01

    The High Frequency Active Auroral Research Program (HAARP) is a joint Air Force and Navy facility which is used to conduct ionospheric modification experiments. Artificial airglow was first observed at HAARP in 1999 [Pedersen and Carlson, 2001] and a successful optics campaign in 2001 showed that this airglow could be consistently produced by directing the HF beam along the magnetic field lines [Pedersen et al., 2003]. Artificial airglow experiments at HAARP since then have been used to explore the relationship of electron gyroharmonic transmissions and airglow intensity [Djuth et al., 2005; Kosch et al., 2005], compare airglow measurements to coherent and incoherent scatter radar data [Kosch et al., 2005; Kosch et al., 2007], and observe the altitude profiles and tomography of the airglow with the aid of multiple camera locations [Pedersen et al., 2008]. In 2003, a heating experiment during auroral conditions unexpectedly resulted in artificial airglow intense enough to be viewed by the naked eye [Pedersen and Gerken, 2005]. Images of small-scale features in artificial airglow serve as a passive means of measuring ionospheric structure. It is important to understand ionospheric structure not only for basic research purposes but also for applications such as improved satellite communications. Telescopic observations of artificial airglow have been conducted at HAARP since 2000, first with a prototype instrument deployed by Stanford University and then by the HAARP telescopic imaging system. Recently, bright airglow emissions were observed on multiple nights during the 2008 winter campaign. Two nights of particular interest were February 26 and 27 with small-scale structure observed by the telescope on both nights. An overview of this system's capabilities and key observations thus far will be presented.

  13. Observation of the June 22, 2015 G4 storm by HiT&MiS: an Echelle Spectrograph for Auroral and Airglow Studies

    NASA Astrophysics Data System (ADS)

    Aryal, S.; Hewawasam, K.; Maguire, R.; Chakrabarti, S.; Cook, T.; Martel, J.; Baumgardner, J. L.

    2015-12-01

    Observation of the June 22, 2015 G4 storm by HiT&MiS: an Echelle Spectrograph for Auroral and Airglow Studies Saurav Aryal1 , Kuravi Hewawasam1, Ryan Maguire1, Supriya Chakrabarti1, Timothy Cook1, Jason Martel1 and Jeffrey L Baumgardner2, (1) University of Massachusetts Lowell, Lowell, MA, United States, (2)Boston University, Boston, MA, United StatesA High-Throughput and Multi-slit Imaging Spectrograph (HiT&MIS) has been developed by our group. The spectrograph uses an echelle grating that operates at high dispersion orders (28-43) such that extended sources for airglow and auroral emissions can be observed at high resolution (about 0.02 nm). By using four slits (instead of the conventional one slit setup), with the appropriate foreoptics it images extended emissions along a long field of view of about 0.1° × 50°. It observes spectral regions around six prominent atmospheric emission lines (HI 656.3 nm, HI 486.1 nm, OI 557.7 nm, OI 630.0 nm, OI 777.4 nm and N+2 427.8 nm) using order sorting interference filters at the entrance slits and a filter mosaic on an image plane. We present observations from the instrument during the June 22, 2015 G4 storm. OI 557.7 nm (green line) and OI 630.0 nm (red line) showed strong brightness enhancements that lasted throughout the night from 8 P.M June 22, 2015 to 3 AM June 23,2015 when compared to the same times after the storm had passed.

  14. Characteristics of the O+(2P-2D) 732.0 and 733.0 nm airglow emissions observed with WINDII and simulated with the C-IAM

    NASA Astrophysics Data System (ADS)

    Shepherd, Gordon G.; Cho, Young-Min; Fomichev, Victor I.; Martynenko, Oleg V.

    2014-08-01

    This paper provides new data on the O+(2P-2D) 732 nm and 733 nm daytime airglow emissions that enhance our understanding of the role that local and conjugate photoelectrons play in the excitation of this emission, updating earlier investigations of its production by solar EUV photoionization of neutral atomic oxygen. The Wind Imaging Interferometer on the Upper Atmosphere Research Satellite, launched in 1991, retrieved these emissions using a filter primarily intended for observations of the hydroxyl P1(2) line but with invalid results. The first corrected results are presented here and compared with simulations by the Canadian Ionosphere and Atmosphere Model. Reasonable agreement is obtained in terms of vertical profiles, solar flux, and solar zenith angle variations. Observations made during local twilight demonstrate that conjugate photoelectrons do not contribute to the excitation of this emission. This paves the way for future determinations of atomic oxygen concentrations.

  15. OI 630.0 nm Night Airglow Observations during the Geomagnetic Storm on November 20, 2003 at Kolhapur (P43)

    NASA Astrophysics Data System (ADS)

    Sharma, A. K.; et al.

    2006-11-01

    sharma_ashokkumar@yahoo.com The ground based photometric observations of OI 630 nm emission line have been carried out from Kolhapur station (Geog. Lat.16.8˚N, Geo. Long 74.2˚E), India during the period of the largest geomagnetic storm of the solar cycle 23 which occurred on 20 November 2003, with minimum Dst index 472 nT occurring around mid-night hours. We observed that on 19 November 2003 which was geomagnetically quiet day, the airglow activity of OI 630 nm emission was subdued and it was decreasing monotonically. However, on the night of November 20, 2003 the enhancement is observed during geomagnetic storm due to the increased electron density at the altitude of the F region which is related to the downward transport of electron from the plasmasphere to the F-region. Airglow intensity at OI 630.0 nm showed increase around midnight on November 21, 2003 but comparatively on a smaller scale. On this night the DST index was about 100 nT. This implies that the effect of the geomagnetic storm persisted on that night also. These observations have been explained by the penetration magnetospheric electric field to the low latitude region and the subsequent modulation of meridional wind during the magnetic disturbance at night.

  16. An observation of polar auroral and airglow from the ISIS-II spacecraft.

    NASA Technical Reports Server (NTRS)

    Shepherd, G. G.; Anger, C. D.; Brace, L. H.; Maier, E. J.; Burrows, J. R.; Heikkila, W. J.; Hoffman, J.; Whitteker, J. H.

    1973-01-01

    This is a preliminary but comprehensive report on coordinated data obtained with the ISIS-II spacecraft, fourth in the ISIS series, launched 1 April 1971, into a near circular 1400 km orbit. The capabilities of the ISIS-I spacecraft have been extended in a number of ways, including the global mapping of the 3914, 5577 and 6300 A emissions. Data obtained during a 30-min pass over the south pole depict the nightside oval and polar cap, as well as mid-latitude airglow effects; these data are described and discussed.

  17. Distribution of atomic oxygen in the upper atmosphere deduced from Ogo 6 airglow observations.

    NASA Technical Reports Server (NTRS)

    Donahue, T. M.; Guenther, B.; Thomas, R. J.

    1973-01-01

    The atomic oxygen distribution as a function of altitude between 80 and 120 km and as a function of latitude has been deduced from Ogo 6 557.7-nm airglow photometer data obtained between August 1969 and April 1970. The results indicate that the density ranges from 15 to 50 billion per cu cm at 120 km; that there is a semiannual variation by a factor of 3 in the global average density near 100 km in phase with the satellite drag semiannual effect; and that large latitudinal variations occur with maximums between 40 and 60 deg in the winter hemisphere and sometimes deep minimums in the tropics. The implication of these results for meridional and vertical transport patterns is discussed.

  18. Oxygen airglow emission on Venus and Mars as seen by VIRTIS/VEX and OMEGA/MEX imaging spectrometers

    NASA Astrophysics Data System (ADS)

    Migliorini, A.; Altieri, F.; Zasova, L.; Piccioni, G.; Bellucci, G.; Cardesín Moinelo, A.; Drossart, P.; D'Aversa, E.; Carrozzo, F. G.; Gondet, B.; Bibring, J.-P.

    2011-08-01

    Imaging spectrometers are highly effective instruments for investigation of planetary atmospheres. They present the advantage of coupling the compositional information to the spatial distribution, allowing simultaneous study of chemistry and dynamics in the atmospheres of Venus and Mars. In this work, we summarize recent results about the O 2(a 1Δg) night and day glows, respectively obtained by VIRTIS/Venus Express and OMEGA/Mars Express, the imaging spectrometers currently in orbit around Venus and Mars. The case of the O 2(a 1Δg - X 3Σg-) IR emission at 1.27 μm on the night side of Venus and the day side of Mars is analyzed, pointing out dynamical aspects of these planets, like the detection of gravity waves in their atmospheres. The monitoring of seasonal and daily airglow variations provides hints about the photochemistry on these planets.

  19. Venus Night Airglow: Ground-Based Detection of OH, Observations of O2 Emissions, and Photochemical Model

    NASA Astrophysics Data System (ADS)

    Krasnopolsky, Vladimir A.

    2009-09-01

    Venus nightglow was observed at NASA IRTF using a high-resolution long-slit spectrograph CSHELL on 13/01/2009 and 21/06/2009, when Venus was near its maximum solar elongations and geocentric velocities. The instrument resolution element at resolving power of 4x104 is smaller than the Doppler shift, and careful subtraction of telluric emission and absorption lines can be made. The observations refer to LT=21:30 and 4:00 on Venus, respectively. Both total intensity of the O2 airglow at 1.27 mu and its rotational temperature are extracted from each observed spectrum. The observed O2 nightglow intensity is 0.7 MR at 21:30 and between 25°S and 25°N declining to 0.35 MR at 35°S and 35°N, and the temperature increases from 175±5 K near the equator to 210±5 K at ±35°. We have found a narrow window at 2.94 mu that covers the OH (1-0) P1(4.5) and (2-1) Q1(1.5) airglow lines. The detected line intensities are converted into the band intensities assuming the rotational temperature of 250 K from the VEX OH observations. The OH (1-0) band is 5.5±1.7 kR and 8.8±2.0 kR at LT = 21:30 and 4:00, respectively. The OH (2-1) band is 2.3±0.7 kR at 4:00. These intensities are weaker than those observed by VEX by a factor of 1.4-2. A photochemical model for the nightglow of O2, NO, and OH has been made. The model extends from 80 to 120 km and involves 54 reactions of 21 species with fluxes of O, N, and H at 120 km as input parameters. While the observed OH vibrational distribution is favorable for the nightglow excitation by O+HO2->OH*+O2, the model shows that the rate of H+O3->OH*+O2 is higher by an order of magnitude. The model agrees with the observations for preferential quenching of OH (v=4-9) to v=0-2 in collisions with CO2. This work is supported by PAST.

  20. OH(v=1 to 9) Relative Population Levels Inferred from VIRTIS/Rosetta Airglow Observations in the Earth's Atmosphere (Invited)

    NASA Astrophysics Data System (ADS)

    Migliorini, A.; Gerard, J. C.; Soret, L.; Piccioni, G.; Capaccioni, F.; Filacchione, G.; Snels, M.

    2015-08-01

    On its way to the comet 67P/Churyumov-Gerasimenko, the Rosetta spacecraft performed three flybys with the Earth, in March 2005, November 2007 and November 2009. The last one was quite suitable to observe the nightside of our planet. The Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on board Rosetta was especially adapted to study the hydroxyl nightglow emissions in the infrared spectral range. The OH v=1,2 sequences were measured simultaneously. We thus investigate the relative population levels of the v=1 to 9 vibrational levels at the same time. Results, obtained using our simple 1-dimension model, are presented for the relative population levels; in particular, the value of level v=1 is derived for the first time, relative to levels up to 9. The vibrational population decreases with increasing vibrational quantum number. Our results are in satisfactorily agreement with previous observations and models developed for mid-latitudes conditions. They favor the models where sudden death deactivation by atomic oxygen is the major process controlling the vibrational population. The observed behavior results to be distinctly different than the OH airglow observations made in the Venus atmosphere with the VIRTIS instrument on board Venus Express, where quenching by CO2 seems to occur with collisional cascades. The authors thank ESA, ASI and all the national space agencies, which support the Rosetta mission (Grants: ASI-INAF I/062/08/0 and ASI-INAF I/050/10/0).

  1. Polar BEAR UV imaging of airglow and aurora-image processing and results

    NASA Astrophysics Data System (ADS)

    Tur, Moshe; Osnovich, Israel; Ravitz, Arnoldo

    1989-09-01

    In late 1986, AFGL launched the Polar BEAR satellite, which was designed for UV imagery of the northern pole region. The AIRS scanning ultraviolet photometer aboard the satellite provides images of day and night auroral structures of unprecedented spectral and spatial resolution at 2 working spectral windows simultaneously. It is necessary to apply geometric and photometric corrections to the image in order to enhance and map it onto the ionosphere. Furthermore, satellite attitude corrections are imperative to assure that image coordinates are properly rotated to the real-time body reference system. To the best knowledge of the authors, this project is the first one to fully include geometric and photometric corrections to VUV images of the ionosphere.

  2. Cassini UVIS Observations of Titan Ultraviolet Airglow Spectra with Laboratory Modeling from Electron- and Proton-Excited N2 Emission Studies

    NASA Astrophysics Data System (ADS)

    Ajello, J. M.; West, R. A.; Malone, C. P.; Gustin, J.; Esposito, L. W.; McClintock, W. E.; Holsclaw, G. M.; Stevens, M. H.

    2011-12-01

    Joseph M. Ajello, Robert A. West, Rao S. Mangina Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 Charles P. Malone Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 & Department of Physics, California State University, Fullerton, CA 92834 Michael H. Stevens Space Science Division, Naval Research Laboratory, Washington, DC 20375 Jacques Gustin Laboratoire de Physique Atmosphérique et Planétaire, Université de Liège, Liège, Belgium A. Ian F. Stewart, Larry W. Esposito, William E. McClintock, Gregory M. Holsclaw Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303 E. Todd Bradley Department of Physics, University of Central Florida, Orlando, FL 32816 The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed photon emissions of Titan's day and night limb-airglow and disk-airglow on multiple occasions, including three eclipse observations from 2009 through 2010. The 77 airglow observations analyzed in this paper show EUV (600-1150 Å) and FUV (1150-1900 Å) atomic multiplet lines and band emissions (lifetimes less than ~100 μs), including the Lyman-Birge-Hopfield (LBH) band system, arising from photoelectron induced fluorescence and solar photo-fragmentation of molecular nitrogen (N2). The altitude of peak UV emission on the limb of Titan during daylight occurred inside the thermosphere/ionosphere (near 1000 km altitude). However, at night on the limb, the same emission features, but much weaker in intensity, arise in the lower atmosphere below 1000 km (lower thermosphere, mesosphere, haze layer) extending downwards to near the surface at ~300 km, possibly resulting from proton- and/or heavier ion-induced emissions as well as secondary-electron-induced emissions. The eclipse observations are unique. UV emissions were observed during only one of the three eclipse events, and no Vegard-Kaplan (VK) or LBH emissions were seen. Through regression analysis using

  3. Lightning induced brightening in the airglow layer

    SciTech Connect

    Boeck, W.L. ); Vaughan, O.H. Jr.; Blakeslee, R. ); Vonnegut, B. ); Brook, M. )

    1992-01-24

    This report describes a transient luminosity observed at the altitude of the airglow layer (about 95 km) in coincidence with a lightning flash in a tropical oceanic thunderstorm directly beneath it. This event provides new evidence of direct coupling between lightning and ionospheric events. This luminous event in the ionosphere was the only one of its kind observed during an examination of several thousand images of lightning recorded under suitable viewing conditions with Space Shuttle cameras. Several possible mechanisms and interpretations are discussed briefly.

  4. Gravity Wave Energetics Determined From Coincident Space-Based and Ground-Based Observations of Airglow Emissions

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Significant progress was made toward the goals of this proposal in a number of areas during the covered period. Section 5.1 contains a copy of the originally proposed schedule. The tasks listed below have been accomplished: (1) Construction of space-based observing geometry gravity wave model. This model has been described in detail in the paper accompanying this report (Section 5.2). It can simulate the observing geometry of both ground-based, and orbital instruments allowing comparisons to be made between them. (2) Comparisons of relative emission intensity, temperatures, and Krassovsky's ratio for space- and ground-based observing geometries. These quantities are used in gravity wave literature to describe the effects of the waves on the airglow. (3) Rejection of Bates [1992], and Copeland [1994] chemistries for gravity wave modeling purposes. Excessive 02(A(sup 13)(Delta)) production led to overproduction of O2(b(sup 1)(Sigma)), the state responsible for the emission of O2. Atmospheric band. Attempts were made to correct for this behavior, but could not adequately compensate for this. (4) Rejection of MSX dataset due to lack of coincident data, and resolution necessary to characterize the waves. A careful search to identify coincident data revealed only four instances, with only one of those providing usable data. Two high latitude overpasses and were contaminated by auroral emissions. Of the remaining two mid-latitude coincidences, one overflight was obscured by cloud, leaving only one ten minute segment of usable data. Aside from the statistical difficulties involved in comparing measurements taken in this short period, the instrument lacks the necessary resolution to determine the vertical wavelength of the gravity wave. This means that the wave cannot be uniquely characterized from space with this dataset. Since no observed wave can be uniquely identified, model comparisons are not possible.

  5. Spatial and temporal behavior of atomic oxygen determined by Ogo 6 airglow observations

    NASA Technical Reports Server (NTRS)

    Donahue, T. M.; Guenther, B.; Thomas, R. J.

    1974-01-01

    Maps are produced of the atomic oxygen density near 97 km showing a strong variation in latitude, longitude, universal time, and time of year. These densities are deduced from atomic oxygen green nightglow observations carried out from Ogo 6. Meridional wind patterns needed to support the asymmetries observed in local oxygen production and loss rates are deduced.

  6. SABER Observations of the OH Meinel Airglow Variability Near the Mesopause

    NASA Technical Reports Server (NTRS)

    Marsh, Daniel R.; Smith, Anne K.; Mlynczak, Martin G.

    2005-01-01

    The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument, one of four on board the TIMED satellite, observes the OH Meinel emission at 2.0 m that peaks near the mesopause. The emission results from reactions between members of the oxygen and hydrogen chemical families that can be significantly affected by mesopause dynamics. In this study we compare SABER measurements of OH Meinel emission rates and temperatures with predictions from a 3-dimensional chemical dynamical model. In general, the model is capable of reproducing both the observed diurnal and seasonal OH Meinel emission variability. The results indicate that the diurnal tide has a large effect on the overall magnitude and temporal variation of the emission in low latitudes. This tidal variability is so dominant that the seasonal cycle in the nighttime emission depends very strongly on the local time of the analysis. At higher latitudes, the emission has an annual cycle that is due mainly to transport of oxygen by the seasonally reversing mean circulation.

  7. Novel Stimulated Electromagnetic Emission Observations with Artificial Airglow Using RF Excitation with HAARP

    NASA Astrophysics Data System (ADS)

    Briczinski, S. J., Jr.; Bernhardt, P. A.; Siefring, C. L.; Michell, R.; Hampton, D. L.; Watkins, B. J.; Bristow, W. A.

    2014-12-01

    High power HF radio waves interacting with the ionosphere provide aeronomers with a unique space-based laboratory capability. The High-Frequency Active Auroral Research Program (HAARP) in Gakona, Alaksa is the world's largest heating facility, producing effective radiated powers in the gigawatt range. Experiments performed at HAARP have allowed researchers to study many non-linear effects of wave-plasma interactions. Stimulated Electromagnetic Emissions (SEE) are of interest to the ionospheric community for its diagnostic purposes. Typical SEE experiments at HAARP have focused on characterizing the parametric decay of the electromagnetic pump wave into several different wave modes such as upper and lower hybrid, ion acoustic, ion-Bernstein and electron-Bernstein. Recent HAARP experiments have used both conventional and novel techniques to excite ionospheric disturbances at gyroharmonic frequencies. Stable layers of artificial ionization have been generated using a "twisted beam" pattern with the heating array. Compared to pencil beam techniques, these layers are long-lived and produce their own unique SEE patterns. The "downshifted mass" or DSM has shown to be a strong indicator of artificial ionization generation. Additionally, several other previously uncharacterized SEE features have been observed. These emissions are under study to be linked with other heating phenomena such as enhanced optical emissions, ion and plasma line generation, HF radar backscatter and enhanced electron acceleration.

  8. Light Phenomena over the ESO Observatories I: Airglow

    NASA Astrophysics Data System (ADS)

    Christensen, L. L.; Noll, S.; Horálek, P.

    2016-03-01

    Airglow, the faint light emitted by the Earth’s atmosphere, has in recent years been frequently photographed in large field images taken at ESO’s observatories. The nature of the airglow is briefly described and example images are shown, capturing the variety of the displays.

  9. A rocket-borne airglow photometer

    NASA Technical Reports Server (NTRS)

    Paarmann, L. D.; Smith, L. G.

    1977-01-01

    The design of a rocket-borne photometer to measure the airglow emission of ionized molecular nitrogen in the 391.4 nm band is presented. This airglow is a well known and often observed phenomenon of auroras, where the principal source of ionization is energetic electrons. It is believed that at some midlatitude locations energetic electrons are also a source of nighttime ionization in the E region of the ionosphere. If this is so, then significant levels of 391.4 nm airglow should be present. The intensity of this airglow will be measured in a rocket payload which also contains instrumentation to measured in a rocket payload which also contains instrumentation to measure energetic electron differential flux and the ambient electron density. An intercomparison of the 3 experiments in a nightime launch will allow a test of the importance of energetic electrons as a nighttime source of ionization in the upper E region.

  10. Near-infrared oxygen airglow from the Venus nightside

    NASA Technical Reports Server (NTRS)

    Crisp, D.; Meadows, V. S.; Allen, D. A.; Bezard, B.; Debergh, C.; Maillard, J.-P.

    1992-01-01

    Groundbased imaging and spectroscopic observations of Venus reveal intense near-infrared oxygen airglow emission from the upper atmosphere and provide new constraints on the oxygen photochemistry and dynamics near the mesopause (approximately 100 km). Atomic oxygen is produced by the Photolysis of CO2 on the dayside of Venus. These atoms are transported by the general circulation, and eventually recombine to form molecular oxygen. Because this recombination reaction is exothermic, many of these molecules are created in an excited state known as O2(delta-1). The airglow is produced as these molecules emit a photon and return to their ground state. New imaging and spectroscopic observations acquired during the summer and fall of 1991 show unexpected spatial and temporal variations in the O2(delta-1) airglow. The implications of these observations for the composition and general circulation of the upper venusian atmosphere are not yet understood but they provide important new constraints on comprehensive dynamical and chemical models of the upper mesosphere and lower thermosphere of Venus.

  11. Mesospheric Gravity Waves over Indian Regions using Sodium Airglow Measurements

    NASA Astrophysics Data System (ADS)

    Sarkhel, Sumanta; Sekar, R.; Chakrabarty, D.; Narayanan, R.

    In order to identify the dominant modes of mesospheric gravity waves, sodium (Na) airglow mea-surements were carried out in campaign modes during November, 2006 -February, 2009 over Mt. Abu (24.6o N, 72.7o E) and Gadanki (13.5o N, 79.2o E) using a narrow-band and narrow field-of-view Na airglow photometer. The airglow observations yield the temporal variation of altitude-integrated Na airglow intensity. Spectral analyses were carried out using Lomb-Scargle technique that can handle unevenly-spaced Na airglow intensity variation. The power spectra indicate that 15-30 min periods, associated with the mesospheric gravity wave activities, are present in the Na airglow intensity variation over both Mt. Abu and Gadanki. In addition to that, the altitude profiles of upper mesospheric temperature during the observational period were obtained from SABER instrument onboard TIMED satellite over both the sites. Inter-estingly, the average mesospheric temperature profiles over both the sites reveal the mesopause height to be at 98 km. However, on a few occasions, it is observed that the mesopause heights lie a scale height below than 98 km and coincide with the typical Na airglow emission height. The dominant periods derived from the Na airglow variation are significantly different on those occasions. These results will be discussed in the light of mesospheric dynamics and its role in Na airglow intensity variation.

  12. Heater-induced ionization inferred from spectrometric airglow measurements

    NASA Astrophysics Data System (ADS)

    Hysell, D. L.; Miceli, R. J.; Varney, R. H.; Schlatter, N.; Huba, J. D.

    2013-12-01

    Spectrographic airglow measurements were made during an ionospheric modification experiment at HAARP on March 12, 2013. Artificial airglow enhancements at 427.8, 557.7, 630.0, 777.4, and 844.6 nm were observed. On the basis of these emissions and using a methodology based on the method of Backus and Gilbert [1968, 1970], we estimate the suprathermal electron population and the subsequent equilibrium electron density profile, including contributions from electron impact ionization. We find that the airglow is consistent with significant induced ionization in view of the spatial intermittency of the airglow.

  13. HF-induced airglow structure as a proxy for ionospheric irregularity detection

    NASA Astrophysics Data System (ADS)

    Kendall, E. A.

    2013-12-01

    The High Frequency Active Auroral Research Program (HAARP) heating facility allows scientists to test current theories of plasma physics to gain a better understanding of the underlying mechanisms at work in the lower ionosphere. One powerful technique for diagnosing radio frequency interactions in the ionosphere is to use ground-based optical instrumentation. High-frequency (HF), heater-induced artificial airglow observations can be used to diagnose electron energies and distributions in the heated region, illuminate natural and/or artificially induced ionospheric irregularities, determine ExB plasma drifts, and measure quenching rates by neutral species. Artificial airglow is caused by HF-accelerated electrons colliding with various atmospheric constituents, which in turn emit a photon. The most common emissions are 630.0 nm O(1D), 557.7 nm O(1S), and 427.8 nm N2+(1NG). Because more photons will be emitted in regions of higher electron energization, it may be possible to use airglow imaging to map artificial field-aligned irregularities at a particular altitude range in the ionosphere. Since fairly wide field-of-view imagers are typically deployed in airglow campaigns, it is not well-known what meter-scale features exist in the artificial airglow emissions. Rocket data show that heater-induced electron density variations, or irregularities, consist of bundles of ~10-m-wide magnetic field-aligned filaments with a mean depletion depth of 6% [Kelley et al., 1995]. These bundles themselves constitute small-scale structures with widths of 1.5 to 6 km. Telescopic imaging provides high resolution spatial coverage of ionospheric irregularities and goes hand in hand with other observing techniques such as GPS scintillation, radar, and ionosonde. Since airglow observations can presumably image ionospheric irregularities (electron density variations), they can be used to determine the spatial scale variation, the fill factor, and the lifetime characteristics of

  14. Interpretation of satellite airglow observations during the March 22, 1979, magnetic storm, using the coupled ionosphere-thermosphere model developed at University College, London

    NASA Technical Reports Server (NTRS)

    Parish, H. F.; Gladstone, G. R.; Chakrabarti, S.

    1994-01-01

    The University of California, Berkeley, extreme ultraviolet spectrometer aboard the U.S. Air Force STP 78-1 satellite measured emission features in the Earth's dayglow due to neutral and ionized species in the atmosphere, in the 35 to 140-nm range. The spectrometer was operating between March 1979 and March 1980, including the period of the magnetic storm on March 22, 1979. Some of these measurements are interpreted using the predictions of the three-dimensional time-dependent coupled ionosphere-thermosphere model developed at University College, London. The observations show a reduction in the atomic oxygen 130.4-nm airglow emission at high northern latitudes following the storm. Model simulations show that this reduction in 130.4-nm emission is associated with an increase in the O2/O ratio. Analysis of model results using electron transport and radiative transport codes show that the brightness of 130.4-nm emission at high latitudes due to resonantly scattered sunlight is approximately twice that due to photoelectron impact excitation. However, the observed decrease in the brightness at high northern latitudes is mainly due to a change in the photoelectron impact source, which contributes approximately 75% of the total, as well as its multiple scattering component; for the photoelectron impact source at 70 deg latitude and 200 km altitude, the reduction in multiple scattering is 1.5 times greater than the reduction in the initial excitation. The reduction in the airglow emission is visible only in the norther n hemisphere because the south pole was not sunlit over the storm period. The comparison of model results with observations suggests that 130.4-nm emission may be useful as a tracer for global changes in the concentration of atomic energy.

  15. Solar Irradiance and Thermospheric Airglow Rocket Experiments

    NASA Astrophysics Data System (ADS)

    Solomon, Stanley C.

    1998-01-01

    This report describes work done in support of the Solar Irradiance and Thermospheric Air-glow Rocket Experiments at the University of Colorado for NASA grant NAG5-5021 under the direction of Dr. Stanley C. Solomon. (The overall rocket program is directed by Dr. Thomas N. Woods, formerly at the National Center for Atmospheric Research, and now also at the University of Colorado, for NASA grant NAG5-5141.) Grant NAG5-5021 provided assistance to the overall program through analysis of airglow and solar data, support of two graduate students, laboratory technical services, and field support. The general goals of the rocket program were to measure the solar extreme ultraviolet spectral irradiance, measure the terrestrial far-ultraviolet airglow, and analyze their relationship at various levels of solar activity, including near solar minimum. These have been met, as shown below. In addition, we have used the attenuation of solar radiation as the rocket descends through the thermosphere to measure density changes. This work demonstrates the maturity of the observational and modeling methods connecting energetic solar photon fluxes and airglow emissions through the processes of photoionization and photoelectron production and loss. Without a simultaneous photoelectron measurement, some aspects of this relationship remain obscure, and there are still questions pertaining to cascade contributions to molecular and atomic airglow emissions. However, by removing the solar irradiance as an "adjustable parameter" in the analysis, significant progress has been made toward understanding the relationship of far-ultraviolet airglow emissions to the solar and atmospheric conditions that control them.

  16. Equatorial airglow and the ionospheric geomagnetic anomaly.

    NASA Technical Reports Server (NTRS)

    Chandra, S.; Reed, E. I.; Troy, B. E., Jr.; Blamont, J. E.

    1973-01-01

    Ogo 4 observations of the O I (6300-A) emissions have revealed a global pattern hitherto undetected from the ground-based observations. It is seen that the postsunset emission of O I (6300 A) in October 1967 is very asymmetrical with respect to the geomagnetic equator in certain longitude regions and shows poor correlation with the electron density measured simultaneously from the same spacecraft. This asymmetry is less marked in the UV airglow, O I (1356 A), which appears to vary as the square of the maximum electron density in the F region. The horizon scan data of the 6300-A airglow reveal that the latitudinal asymmetry is associated with asymmetry in the height of the O I (6300-A) emission and hence with the altitude of the F2 peak. From the correlative studies of the airglow and the ionospheric measurements the mechanisms of the UV and the 6300 A emissions are discussed in terms of the processes involving radiative and dissociative recombination. Theoretical expressions are developed which relate the airglow data to the ionospheric parameters.

  17. The global characteristics of atmosphere emissions in the lower thermosphere and their aeronomic implications. [OGO-4 airglow photometric observations of oxygen

    NASA Technical Reports Server (NTRS)

    Reed, E. I.; Chandra, S.

    1974-01-01

    The green line of atomic oxygen and the Herzberg bands of molecular oxygen as observed from the OGO-4 airglow photometer are discussed in terms of their spatial and temporal distributions and their relation to the atomic oxygen content in the lower thermosphere. Daily maps of the distribution of emissions show considerable structure (cells, patches, and bands) with appreciable daily changes. When data are averaged over periods of several days in length, the resulting patterns have occasional tendencies to follow geomagnetic parallels. The Seasonal variations are characterized by maxima in both the Northern and Southern Hemispheres in October, with the Northern Hemisphere having substantially higher emission rates. Formulae are derived relating the vertical column emission rates of the green line and the Herzberg bands to the atomic oxygen peak density. Global averages for the time period for these data (August 1967 to January 1968), when converted to maximum atomic oxygen densities near 95 km, have a range of 2.0 x 10 to the 11th power/cu cm 2.7 x 10 to the 11th power/cu cm.

  18. Jupiter's nightside airglow and aurora.

    PubMed

    Gladstone, G Randall; Stern, S Alan; Slater, David C; Versteeg, Maarten; Davis, Michael W; Retherford, Kurt D; Young, Leslie A; Steffl, Andrew J; Throop, Henry; Parker, Joel Wm; Weaver, Harold A; Cheng, Andrew F; Orton, Glenn S; Clarke, John T; Nichols, Jonathan D

    2007-10-12

    Observations of Jupiter's nightside airglow (nightglow) and aurora obtained during the flyby of the New Horizons spacecraft show an unexpected lack of ultraviolet nightglow emissions, in contrast to the case during the Voyager flybys in 1979. The flux and average energy of precipitating electrons generally decrease with increasing local time across the nightside, consistent with a possible source region along the dusk flank of Jupiter's magnetosphere. Visible emissions associated with the interaction of Jupiter and its satellite Io extend to a surprisingly high altitude, indicating localized low-energy electron precipitation. These results indicate that the interaction between Jupiter's upper atmosphere and near-space environment is variable and poorly understood; extensive observations of the day side are no guide to what goes on at night. PMID:17932286

  19. A global view of the molecular oxygen night airglow

    NASA Astrophysics Data System (ADS)

    Hays, Paul B.; Kafkalidis, Julie F.; Skinner, Wilbert R.; Roble, Raymond G.

    2003-10-01

    The High-Resolution Doppler Imager on the Upper Atmosphere Research Satellite has observed the O2 atmospheric band nightglow at extremely high spatial resolution of 50 km in the horizontal over much of Earth's surface. These observations of the oxygen nightglow are shown to be a good surrogate for atomic oxygen outflow from the thermosphere and subsequent recombination in the upper mesosphere. The distribution of enhanced airglow and recombination verify the previous observations that bright regions of the nightglow are associated with descending motion, where the tides are transporting atomic oxygen out of the thermosphere, and regions of decreased airglow are associated with ascending tidal motion. The detailed observations of the global airglow at a scale of 100 km present a much more complex picture, however. The tidally enhanced regions are extremely structured, with strong longitudinal and latitudinal variability in brightness and associated atomic oxygen recombination. These structured regions are persistent on a timescale of a day or more, with certain regions of the globe exhibiting enhanced airglow much of the time. These regions are present over the entire night side of the globe but are strongly modulated by the ascending and descending tidal motions. A theoretical study of these enhancements suggests that they are caused by the upward propagation of gravity waves, which break in the high mesosphere and induce strong vertical motion in the atmosphere. It is interesting that the primary cause of the increased transport of atomic oxygen is vertical motion rather than the conventional enhanced turbulence explanation. These gravity waves are associated with wind shear and strong convective activity in the troposphere and often appear in certain preferred locations where convective activity is expected. These observations have important implications for the basic processes by which momentum and energy are deposited in the upper mesosphere. We suggest that

  20. OGO-4 observations of the 6300 A night airglow from 40 deg N to 40 deg S: A set of 19 color maps

    NASA Technical Reports Server (NTRS)

    Reed, E. I.; Blamont, J. E.

    1972-01-01

    Data for the 6300 A line of atomic oxygen from the main body airglow photometer on the OGO-D satellite are summarized in a set of 19 maps for various local times at night between 30 August 1967 and 10 January 1968.

  1. Discovery of a new orange feature from FeO in the night airglow with the OSIRIS spectrograph

    NASA Astrophysics Data System (ADS)

    Evans, W. F.; Gattinger, R.; Llewellyn, E. J.; Degenstein, D. A.; Slanger, T. G.

    2010-12-01

    The discovery of a new airglow feature in the earth’s atmosphere is presented. The FeO orange feature has been detected in the night airglow spectrum with the OSIRIS spectrograph on the ODIN spacecraft. The orange chemiluminescent airglow has been measured in the spectral region from 530 nm to 650 nm. The OSIRIS imaging spectrograph measures the airglow spectrum over the 275 to 815 nm wavelength range. At the spectral resolution of OSIRIS, the band systems of FeO appear as a weak continuum-like structure in the 600 nm region at 85 km in the upper mesosphere. As the satellite scans, spectra are obtained of the terrestrial limb with tangent altitudes ranging between 5 km and 110 km. Since the instrument is a CCD spectrograph, all wavelengths are exposed simultaneously thus avoiding the effect of temporal intensity variations inherently present in spectrally scanning instruments. The relative spectral sensitivity over the entire wavelength range has been quantified to yield an estimated 5% precision. In order to maintain accurate on-orbit spectral calibrations an atmospheric radiation model with multiple Rayleigh scattering is employed to regularly update the OSIRIS spectral response. Averages of spectra at a series of tangent limb altitudes were assembled from numerous limb scans at low latitudes. Limb radiance altitude profiles for a number of observed spectral features were obtained from these averaged spectra. These radiance profiles were inverted to obtain volume emission rate altitude profiles. Synthetic spectra for the hydroxyl and O2 Herzberg airglow emission bands were generated and scaled with the observed band intensities to remove the known airglow components in order to isolate the underlying airglow feature. Tropical latitudes were chosen to minimize the classic green airglow continuum from the reaction of nitric oxide with atomic oxygen since nitric oxide is small at 90 km in the tropics. Other potential photochemical sources of the orange glow are

  2. Analysis of close conjunctions between dayside polar cap airglow patches and flow channels by all-sky imager and DMSP

    NASA Astrophysics Data System (ADS)

    Wang, Boyi; Nishimura, Yukitoshi; Lyons, Larry R.; Zou, Ying; Carlson, Herbert C.; Frey, Harald U.; Mende, Stephen B.

    2016-09-01

    Recent imager and radar observations in the nightside polar cap have shown evidence that polar cap patches are associated with localized flow channels. To understand how flow channels propagate from the dayside auroral oval into the polar cap, we use an all-sky imager in Antarctica and DMSP (F13, F15, F16, F17 and F18) to determine properties of density and flows associated with dayside polar cap patches. We identified 50 conjunction events during the southern winter seasons of 2007-2011. In a majority (45) of events, longitudinally narrow flow enhancements directed anti-sunward are found to be collocated with the patches, have velocities (up to a few km/s) substantially larger than the large-scale background flows (~500 m/s) and have widths comparable to patch widths (~400 km). While the patches start with poleward moving auroral forms (PMAFs) as expected, many PMAFs propagate azimuthally away from the noon over a few hours of MLT, resulting in formation of polar cap patches quite far away from the noon, as early as ~6 MLT. The MLT separation from the noon is found to be proportional to the IMF |By|. Fast polar cap flows of >~1500 m/s are predominantly seen during large IMF |By| and small |Bz|. The presence of fast, anti-sunward flow channels associated with the polar cap patches suggests that the flow channels form in the dayside auroral oval through transient reconnection and can be the source of flow channels propagating into the polar cap.

  3. Nitrogen airglow sources - Comparison of Triton, Titan, and earth

    NASA Technical Reports Server (NTRS)

    Strobel, Darrell F.; Meier, R. R.; Summers, Michael E.; Strickland, Douglas J.

    1991-01-01

    The individual contributions of direct solar excitation, photoelectron excitation, and magnetospheric electron excitation of Triton and Titan airglow observed by the Voyager Ultraviolet Spectrometer (UVS) are quantified. The principal spectral features of Triton's airglow are shown to be consistent with precipitation of magnetospheric electrons with power dissipation about 500 million W. Solar excitation rates of the dominant N2 and N(+) emission features are factors of 2-7 weaker than magnetospheric electron excitation. On Titan, the calculated disk center and bright limb N(+) 1085 A intensities due to solar excitation agree with observed values, while the 970 A feature is mostly N21 c5 band emission. The calculated LBH intensity by photoelectrons suggests that magnetospheric electrons play a minor role in Titan's UV airglow. On earth, solar/photoelectron excitation explains the observed N(+) 1085 A and LBH intensites and accounts for only 40 percent of the N(+) 916 A intensity.

  4. Recent observations of dynamic variations of the thermosphere and ionosphere by the Optical Mesosphere Thermosphere Imagers (OMTIs)

    NASA Astrophysics Data System (ADS)

    Shiokawa, Kazuo; Otsuka, Yuichi; Oyama, Shin-ichiro; Lakshmi Narayanan, Viswanathan; Ceren Moral, Aysegul

    2016-07-01

    The Optical Mesosphere Thermosphere Imagers (OMTIs) consist of fourteen all-sky cooled-CCD imagers, five Fabry-Perot interferometers (FPIs), three meridian scanning photometers, and four airglow temperature photometers. They measure two-dimensional pattern, Doppler wind, and temperature through airglow emissions from oxygen (wavelength: 557.7 nm) and OH (near infrared band) in the mesopause region (80-100 km) and from oxygen (630.0 nm) in the thermosphere/ionosphere (200-300 km). They are in automatic operation at 14 stations at Australia, Indonesia, Thailand, far-east Russia, Japan, Canada, Hawaii, Norway, and Nigeria. Station information and quick look plots are available at http://stdb2.stelab.nagoya-u.ac.jp/omti/. In this presentation we show recent observations of the dynamical variations of the thermosphere and ionosphere observed by OMTIs at various latitudes from the equator to the auroral zone.

  5. Mesospheric hydroxyl airglow signatures of acoustic and gravity waves generated by transient tropospheric forcing

    NASA Astrophysics Data System (ADS)

    Snively, J. B.

    2013-09-01

    Numerical model results demonstrate that acoustic waves generated by tropospheric sources may produce cylindrical "concentric ring" signatures in the mesospheric hydroxyl airglow layer. They may arrive as precursors to upward propagating gravity waves, generated simultaneously by the same sources, and produce strong temperature perturbations in the thermosphere above. Transient and short-lived, the acoustic wave airglow intensity and temperature signatures are predicted to be detectable by ground-based airglow imaging systems and may provide new insight into the forcing of the upper atmosphere from below.

  6. Mesoscale field-aligned irregularity structures (FAIs) of airglow associated with medium-scale traveling ionospheric disturbances (MSTIDs)

    NASA Astrophysics Data System (ADS)

    Sun, Longchang; Xu, Jiyao; Wang, Wenbin; Yue, Xinan; Yuan, Wei; Ning, Baiqi; Zhang, Donghe; Meneses, F. C.

    2015-11-01

    In this paper, we report the evolution (generation, amplification, and dissipation) of optically observed mesoscale field-aligned irregularity structures (FAIs) (~150 km) associated with a medium-scale traveling ionospheric disturbance (MSTID) event. There have not been observations of mesoscale FAIs of airglow before. The mesoscale FAIs were generated in an airglow-depleted front of southwestward propagating MSTIDs that were simultaneously observed by an all-sky imager, a GPS monitor, and a digisonde around Xinglong (40.4°N, 30.5° magnetic latitude), China, on 17/18 February 2012. A normalized cross-correlation method has been used to obtain the velocities of mesoscale FAIs and MSTIDs. The mesoscale FAIs had an obvious northwestward relative velocity to main-body MSTIDs (about 87.0 m/s on average). The direction of this relative velocity was roughly parallel to the depleted fronts. Furthermore, the evolution of the mesoscale FAIs was mostly controlled by the intensity of the depleted fronts. Occurred in a highly elevated ionosphere that had a total electron content depletion associated with large negative airglow perturbations (-25%), the mesoscale FAIs grew rapidly when they experienced southeastward wind, which had a speed of about 100 m/s and were measured by a Fabry-Perot interferometer. A northeastward polarization electric field within a depleted airglow front can play a controlling role in the development of the mesoscale FAIs. The electric field can significantly elevate the ionosphere and move the mesoscale FAIs northwestward by the E × B drift. The processes for the generation and development of the polarization electric field and the mesoscale FAIs, however, need further study.

  7. Mariner 9 ultraviolet spectrometer experiment - Mars airglow spectroscopy and variations in Lyman alpha.

    NASA Technical Reports Server (NTRS)

    Barth, C. A.; Stewart, A. I.; Hord, C. W.; Lane, A. L.

    1972-01-01

    Mariner 9 ultraviolet spectrometer observations show the Mars airglow consists principally of emissions that arise from the interaction of solar ultraviolet radiation with carbon dioxide, the principal constituent of the Mars atmosphere. Two minor constituents, atomic hydrogen and atomic oxygen, also produce airglow emissions. The airglow measurements show that ionized carbon dioxide is only a minor constituent of the ionosphere. Using the airglow measurements of atomic oxygen, it is possible to infer that the major ion is ionized molecular oxygen. The escape rate of atomic hydrogen measured by Mariner 9 is approximately the same as that measured two years earlier by Mariner 6 and 7. If the current escape rate has been operating for 4.5 billion years and if water vapor is the ultimate source, an amount of oxygen has been generated that is far in excess of that observed at present. Mariner 9 observations of Mars Lyman alpha emission over a period of 120 days show variations of 20%.

  8. Wave-coupling from the troposphere to the mesosphere and thermosphere observed by the Optical Mesosphere Thermosphere Imagers (OMTIs)

    NASA Astrophysics Data System (ADS)

    Shiokawa, Kazuo; Otsuka, Yuichi; Takeo, Daiki; Fujinami, Hatsuki

    2016-07-01

    The airglow emissions from the mesopause region and the thermosphere are very useful to monitor dynamical variations of the neutral and plasma atmosphere in the upper atmosphere. The Optical Mesosphere Thermosphere Imagers (OMTIs) measure two-dimensional pattern, Doppler wind, and temperature through airglow emissions from oxygen (wavelength: 557.7 nm) and OH (near infrared band) in the mesopause region (80-100 km) and from oxygen (630.0 nm) in the thermosphere/ionosphere (200-300 km) at various locations in the world. Station information and quick look plots are available at http://stdb2.stelab.nagoya-u.ac.jp/omti/. In this presentation we show recent observations by OMTIs for the vertical coupling of atmospheric gravity waves from the troposphere to the mesopause region and to the thermosphere/ionosphere.

  9. Mesospheric airglow and ionospheric responses to upward-propagating acoustic and gravity waves above tropospheric sources

    NASA Astrophysics Data System (ADS)

    Snively, J. B.; Zettergren, M. D.

    2013-12-01

    The existence of acoustic waves (periods ~1-5 minutes) and gravity waves (periods >4 minutes) in the ionosphere above active tropospheric convection has been appreciated for more than forty years [e.g., Georges, Rev. Geophys. and Space Phys., 11(3), 1973]. Likewise, gravity waves exhibiting cylindrical symmetry and curvature of phase fronts have been observed via imaging of the mesospheric airglow layers [e.g., Yue et al., JGR, 118(8), 2013], clearly associated with tropospheric convection; gravity wave signatures have also recently been detected above convection in ionospheric total electron content (TEC) measurements [Lay et al., GRL, 40, 2013]. We here investigate the observable features of acoustic waves, and their relationship to upward-propagating gravity waves generated by the same sources, as they arrive in the mesosphere, lower-thermosphere, and ionosphere (MLTI). Numerical simulations using a nonlinear, cylindrically-axisymmetric, compressible atmospheric dynamics model confirm that acoustic waves generated by transient tropospheric sources may produce "concentric ring" signatures in the mesospheric hydroxyl airglow layer that precede the arrival of gravity waves. As amplitudes increase with altitude and decreasing neutral density, the modeled acoustic waves achieve temperature and vertical wind perturbations on the order of ~10s of Kelvin and m/s throughout the E- and F-region. Using a coupled multi-fluid ionospheric model [Zettergren and Semeter, JGR, 117(A6), 2012], extended for low-latitudes using a 2D dipole magnetic field coordinate system, we investigate acoustic wave perturbations to the ionosphere in the meridional direction. Resulting perturbations are predicted to be detectable by ground-based radar and GPS TEC measurements, or via in situ instrumentation. Although transient and short-lived, the acoustic waves' airglow and ionospheric signatures are likely to in some cases be observable, and may provide important insight into the regional

  10. Brightening of 630.0 nm equatorial spread-F airglow depletions

    NASA Astrophysics Data System (ADS)

    Martinis, Carlos; Baumgardner, Jeffrey; Mendillo, Michael; Su, Shin-Yi; Aponte, Nestor

    2009-06-01

    Observations from the Boston University all-sky imaging system at Arecibo, Puerto Rico (18.3°N, 66.7°W, 28°N mag), show an unusual behavior of nighttime 630.0-nm airglow depletions. Associated with equatorial spread-F (ESF), these structures move eastward before reversing their motion and become airglow enhancements. Few other cases have been found, all during December solstices. For the case study presented here, data from the Arecibo incoherent scatter radar and the Republic of China Scientific Satellite (ROCSAT-1) provide supporting information. The radar shows that around local midnight the background zonal and meridional plasma motions reverse to westward and southward, respectively. ROCSAT-1 shows enhanced ion density, i.e., a low-latitude plasma blob, above the bright feature recorded by the all-sky imager, indicating a possible connection between both phenomena. Drifts parallel to the magnetic field are observed only in the region where the enhancement occurs. One possible interpretation of this change in the brightness of the depleted structure involves the influence of northward meridional winds and a reversal in the zonal drift motion, most likely caused by a zonal wind reversal.

  11. Airglow events visible to the naked eye

    NASA Technical Reports Server (NTRS)

    Peterson, A. W.

    1979-01-01

    During IR photographic airglow observations covering several years, three naked-eye events have been recorded. Two of these are moving luminous acoustic-gravity-wave groups of some 10-15-km wavelength, which occur near high lunar tide in the atmosphere. The events appear quickly, endure 0.5-1 h, then fade. Visible photos of two events appear enhanced, while little enhancement is present in the IR photos, although the structures are well correlated. If these events are due to OH, it is suggested that some unrecognized mechanism, perhaps a gravity wave interaction, enhances the visible transitions of the OH over the IR transitions. If the events are due to an unrecognized continuum emitter, perhaps NO, its emission must occur at the same height as the OH. Spectra seem to be the only reasonable approach to solving this problem.

  12. Upper Atmospheric Density Retrievals from UVIS Dayglow Observations of Titan

    NASA Astrophysics Data System (ADS)

    Stevens, Michael H.; Evans, J. S.; Ajello, J. M.; Bradley, E. T.; Meier, R. R.; Westlake, J. H.; Waite, J. H.

    2012-10-01

    The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed Titan’s dayside limb on multiple occasions between 2007-2012. The airglow observations reveal the same variety of EUV (600-1150 λ) and FUV (1150-1900 λ) emissions arising from photoelectron impact and photofragmentation of molecular nitrogen (N2) on Earth. Through spectral analysis we extract radiance profiles for each set of UVIS limb emissions in the EUV and FUV, which are attenuated by methane (CH4). Using a terrestrial airglow model adapted to Titan, we derive the N2 and CH4 density profiles using the prescribed solar irradiance for the relevant Cassini orbit and compare the calculated radiance profiles directly with observations. We find that the Titan airglow can be explained by solar driven processes to within the uncertainties of the UVIS observations. Fluctuations in the observed airglow between flybys suggest compositional changes in the background atmosphere. The source of these compositional changes is not yet known, although the interaction of Titan with Saturn’s magnetosphere has been implicated as an important contributing factor. Here we use unique UVIS airglow observations over Titan’s disk to quantify compositional fluctuations with latitude and local time. We furthermore compare N2 and CH4 densities retrieved from the UVIS airglow to in situ observations by the Cassini Ion and Neutral Mass Spectrometer (INMS) and discuss how the UVIS and INMS variations may be related to Titan’s varying plasma environment.

  13. Extensive MRO CRISM Observations of 1.27 micron O2 Airglow in Mars Polar Night and Their Comparison to MRO MCS Temperature Profiles and LMD GCM Simulations

    NASA Technical Reports Server (NTRS)

    Clancy, R. Todd; Sandor, Brad J.; Wolff, Michael J.; Smith, Michael Doyle; Lefevre, Franck; Madeleine, Jean-Baptiste; Forget, Francois; Murchie, Scott L.; Seelos, Frank P.; Seelos, Kim D.; Nair, Hari A.; Toigo, Anthony D.; Humm, David; Kass, David M.; Kleinbahl, Armin; Heavens, Nicholas

    2012-01-01

    The Martian polar night distribution of 1.27 micron (0-0) band emission from O2 singlet delta [O2(1Delta(sub g))] is determined from an extensive set of Mars Reconnaissance Orbiter (MRO) Compact Reconnaissance Imaging Spectral Mapping (CRISM) limb scans observed over a wide range of Mars seasons, high latitudes, local times, and longitudes between 2009 and 2011. This polar nightglow reflects meridional transport and winter polar descent of atomic oxygen produced from CO2 photodissociation. A distinct peak in 1.27 micron nightglow appears prominently over 70-90NS latitudes at 40-60 km altitudes, as retrieved for over 100 vertical profiles of O2(1Delta(sub g)) 1.27 micron volume emission rates (VER). We also present the first detection of much (x80+/-20) weaker 1.58 micron (0-1) band emission from Mars O2(1Delta(sub g)). Co-located polar night CRISM O2(1Delta(sub g)) and Mars Climate Sounder (MCS) (McCleese et al., 2008) temperature profiles are compared to the same profiles as simulated by the Laboratoire de Météorologie Dynamique (LMD) general circulation/photochemical model (e.g., Lefèvre et al., 2004). Both standard and interactive aerosol LMD simulations (Madeleine et al., 2011a) underproduce CRISM O2(1Delta(sub g)) total emission rates by 40%, due to inadequate transport of atomic oxygen to the winter polar emission regions. Incorporation of interactive cloud radiative forcing on the global circulation leads to distinct but insufficient improvements in modeled polar O2(1Delta(sub g)) and temperatures. The observed and modeled anti-correlations between temperatures and 1.27 mm band VER reflect the temperature dependence of the rate coefficient for O2(1Delta(sub g)) formation, as provided in Roble (1995).

  14. Moon based global field airglow: For Artemis or any common Lunar Lander

    NASA Astrophysics Data System (ADS)

    Kozlowski, R. W. H.; Sprague, A. L.; Sandel, B. R.; Hunten, D. M.; Broadfoot, A. L.

    1994-06-01

    An inexpensive, small mass, airglow experiment consisting of a suite of airglow detectors is planned for one or more lunar landers. Solid state detectors measuring light through narrow band filters or concave gratings can integrate emissions from lunar atmospheric constituents and store the information for relay to earth when convenient. The proposed instrument is a simplified version of the Shuttle-borne Arizona Imager-Spectrograph. These zenith and near horizon viewing detectors may allow us to monitor fluctuations in atomic species of oxygen, calcium, sodium, potassium, argon, and neon and OH, if present. This choice of observations would monitor outgassing from the interior (Ar), meteoritic dust flux (Na, K) solar wind sputtering (O, Ca), and outgassing from the surface (implanted Ne, Na, K). A global network could be inexpensively deployed aboard landers carrying a variety of other selenographic instrumentation. Powered by solar cells such a field network will return data applicable to a wide variety of interplanetary medium and solar-lunar interaction problems.

  15. Model studies of time-dependent ducting for high-frequency gravity waves and associated airglow responses in the upper atmosphere

    NASA Astrophysics Data System (ADS)

    Yu, Yonghui

    wave spectra and hence causes noticeable azimuthal variations at higher altitudes. In addition to the spectral analysis applied previously the wave action has been used to interpret the energy coupling between the waves and the mean flow among some atmospheric regions, where the waves are suspected to extract energy from the mean flow at some altitudes and release it to other altitudes. The fifth chapter is a concrete and substantial step connecting theoretical studies and realistic observations through nonlinearly coupling wave dynamic model with airglow chemical reactions. Simulated O (1S) (557.7 nm) airglow images are provided so that they can be compared with observational airglow images. These simulated airglow brightness variations response accordingly with minor species density fluctuations, which are due to propagating and ducting nonlinear gravity waves within related airglow layers. The thermal and wind structures plus the seasonal and geographical variabilities could significantly influence the observed airglow images. By control modeling studies the simulations can be used to collate with concurrent observed data, so that the incoherencies among them could be very useful to discover unknown physical processes behind the observed wave scenes.

  16. Ground-satellite conjugate observations of low-latitude travelling ionospheric disturbances

    NASA Astrophysics Data System (ADS)

    Ceren Moral, Aysegul; Shiokawa, Kazuo; Otsuka, Yuichi; Suzuki, Shin; Liu, Huixin; Yatini, Clara

    2016-07-01

    Equatorial travelling ionospheric disturbances (TIDs) are studied by using three CHAMP satellite overpasses on ground-based 630-nm airglow images. The airglow images are obtained from Kototabang (KTB), Indonesia (geographic coordinates: 0.2S, 100.3E, geomagnetic latitude: 10.6S). From 7-year data from October 2002 to October 2009, April 30, 2006 (event 1), September 28, 2006 (event 2) and April 12, 2004 (event 3) are the only TID events found in both ground and satellite measurements. They show southward-moving structures in 630-nm airglow images. The events 1 and 2 are single pulse with horizontal scales of ~500-1000 km and event 3 show three wave fronts with horizontal scale sizes of 500-700 km. For events 1 and 3, the neutral density in CHAMP shows out-of-phase variations with the airglow intensity, while event 2 is in-phase. For event 1, the relation between electron density and airglow intensity is out of phase, while relationships of event 2 and 3 are unclear. These unclear relationships suggest that ionospheric plasma variation is not the cause of the TIDs. In the case if gravity waves in the thermosphere is the source of the observed TIDs, in-phase and out-of-phase relationships of neutral density and airglow intensity can be explained by different vertical wavelengths of the gravity wave. We estimate possible vertical wavelengths for those events using observed wave parameters and modeled neutral winds.

  17. Radar and Optical Observation of Medium-Scale Traveling Ionospheric Disturbances and Field-Aligned Irregularities in the F Region

    NASA Astrophysics Data System (ADS)

    Otsuka, Y.; Yokoyama, T.; Shiokawa, K.; Ogawa, T.; Yamamoto, M.

    2007-05-01

    We report for the first time simultaneous observation of Medium-Scale Traveling Ionospheric Disturbances (MSTIDs) and Field-Aligned Irregularities (FAIs) in the F region using two all-sky airglow imagers and the MU radar in Japan. The all-sky imagers were operated at Sakata (39.0°N, 139.9°E) and Shigaraki (34.9°N, 136.1°E), Japan. MSTID propagating southwestward was simultaneously observed in 630- nm airglow images at the both sites. To investigate spatial relationship between MSTID and FAIs, FAIs were mapped onto the 630-nm airglow layer (260 km altitude). Altitude of the airglow layer was estimated by the triangulation using all-sky images at Sata and Shigaraki. FAIs with strong echo intensity and upward Doppler velocities coincided with the airglow depleted region due to the MSTIDs. On the other hand, FAIs with weak echo intensity and downward Doppler velocities coincided with the airglow enhancement. The directions of the Doppler velocities is consistent with that of ExB drifts caused by the polarization electric fields associated with the MSTIDs. A model calculation was carried out to simulate electron density perturbations caused by oscillating electric fields due to MSTIDs. The result suggests that FAIs could be generated by the gradient drift instability which operates at the spatial gradient of the electron density associated with the MSTIDs.

  18. Observations of the O2 atmospheric band nightglow by the High Resolution Doppler Imager

    NASA Technical Reports Server (NTRS)

    Burrage, M. D.; Arvin, N.; Skinner, W. R.; Hays, P. B.

    1994-01-01

    During nighttime operation the High Resolution Doppler Imager (HRDI) on the Upper Atmosphere Research Satellite (UARS) measures both the horizontal wind field at about 94 km altitude and the limb brightness of the O2(b(sup 1) Sigma(sup +)(sub g) - Chi(cubed)Sigma(sup +)(sub g)) (0,0) atmospheric band airglow. The dominant feature of the observed emission is a latitudinal and local time dependence which is consistent with the (1,1) diurnal tidal mode. A survey of the available data set from November 1991 to July 1993 reveals a semiannual variation in the peak brightness observed at the equator, with maxima observed at the equinoxes and minima at the solstices. These results are consistent with the long-term variations in the diurnal tidal amplitudes detected in HRDI wind measurements.

  19. Simultaneous Observation of Wave Packet of the Atmospheric Gravity Waves by ISS-IMAP and All-sky Imager

    NASA Astrophysics Data System (ADS)

    Yukino, H.; Saito, A.; Sakanoi, T.; Otsuka, Y.

    2014-12-01

    The spatial scale of the atmospheric gravity wave in the mesosphere and the lower thermosphere was analyzed using the simultaneous observational data of ISS-IMAP and an all-sky imager at Hawaii. There are a plenty of previous studies that discuss the relationship between the wave structures of the mesospheric airglow and the tropospheric events. The problem of the ground-based observation of the airglow is that it cannot distinguish spatial variations from temporal variations for the structures whose scale size is larger than its field-of-view. ISS-IMAP started the observation in October, 2012 to survey the atmospheric gravity waves whose horizontal scale size is 50 km and longer. The spatial resolution of the VIsible-light and infrared Spectrum Imager (VISI) of ISS-IMAP/VISI imaging observation is from 10 km to 25 km. Simultaneous observations start from March 14, 2013. The atmospheric gravity waves that detected by VISI in 762 nm were compared with the observations of ground-based all-sky imagers in 557.7 nm. The generation and the propagation of the atmospheric gravity waves were investigated with this simultaneous observation. The relationship between the tropospheric events and the atmospheric gravity waves in the mesosphere is studied with the wide field-of-view observation by VISI/ISS-IMAP, and the continuous observation of the ground-based imagers. VISI frequently observed wave packets whose scale size is 1,000-2,000 km. These wave packets were observed by the ground-based imager as a series of waves whose wave length is 20-40 km, and that continue for 5-6 hours. The generation, the propagation and the distraction of the atmospheric gravity waves will be discussed in this presentation.

  20. Vacuum-ultraviolet instrumentation for solar irradiance and thermospheric airglow

    NASA Astrophysics Data System (ADS)

    Woods, Thomas N.; Rottman, Gary J.; Bailey, Scott M.; Solomon, Stanley C.

    1994-02-01

    A NASA sounding rocket experiment was developed to study the solar extreme-ultraviolet (EUV) spectral irradiance and its effect on the upper atmosphere. Both the solar flux and the terrestrial molecular nitrogen via the Lyman-Birge-Hopfield bands in the far-ultraviolet (FUV) region were measured remotely from a sounding rocket on October 27, 1992. The rocket experiment also includes EUV instruments from Boston University, but only the National Center for Atmospheric Research's (NCAR)/University of Colorado's (CU) four solar instruments and one airglow instrument are discussed. The primary solar EUV instrument is a 0.25-m Rowland circle EUV spectrograph that has flown on three rockets since 1988 measuring the solar spectral irradiance from 30 to 110 nm with 0.2-nm resolution. Another solar irradiance instrument is an array of six silicon soft x-ray (XUV) photodiodes, each having different metallic filters coated directly on the photodiodes. This photodiode system provides a spectral coverage from 0.1 to 80 nm with approximately 15-nm resolution. The other solar irradiance instrument is a silicon avalanche photodiode coupled with pulse height analyzer electronics. This avalanche photodiode package measures the XUV photon energy, providing a solar spectrum from 50 to 12,400 eV (25 to 0.1 nm) with an energy resolution of about 50 eV. The fourth solar instrument is an XUV imager that images the sun at 17.5 nm with a spatial resolution of 20 arc sec. The airglow spectrograph measures the terrestrial FUV airglow emissions along the horizon from 125 to 160 nm with 0.2-nm spectral resolution. The photon-counting CODACON detectors are used for three of these instruments and consist of coded arrays of anodes behind microchannel plates.

  1. Compositional Variations from UVIS Observations of Titan's Dayglow and Comparisons with in situ INMS Observations

    NASA Astrophysics Data System (ADS)

    Stevens, M. H.; Evans, J. S.; Ajello, J. M.; Bradley, E. T.; Meier, R. R.; Westlake, J. H.; Waite, J. H., Jr.

    2012-04-01

    The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed Titan’s dayside limb on multiple occasions between 2007 and 2011. The airglow observations reveal the same variety of EUV (600-1150Å) and FUV (1150-1900Å) emissions arising from photoelectron excitation and photofragmentation of molecular nitrogen (N2) on Earth. Through spectral analysis we extract radiance profiles for each set of UVIS limb emissions in the EUV and FUV, which are attenuated by methane (CH4). Using a terrestrial airglow model adapted to Titan, we derive the N2 and CH4 density profiles using the prescribed solar irradiance for the relevant Cassini orbit and compare the calculated radiance profiles directly with observations. We find that the UVIS airglow observations can be explained by solar driven processes, although fluctuations in the observed airglow between flybys suggest compositional changes in the background atmosphere. We compare the compositional variations inferred from the UVIS airglow to in situ observations by the Cassini Ion and Neutral Mass Spectrometer (INMS) from the same Titan orbit and discuss how the variations may be related to Titan’s varying plasma environment.

  2. A new perspective on the molecular oxygen and hydroxyl airglow emissions

    NASA Astrophysics Data System (ADS)

    Mlynczak, Martin G.

    The mesospheric molecular oxygen and hydroxyl airglow emissions have traditionally been measured in order to derive minor species abundances or to diagnose dynamical phenomena. We present a new interpretation of these airglow emissions and show them to be fundamental measures of energy deposition from which rates of atmospheric heating are readily derived. The heating rate due to absorption of ultraviolet radiation in the Hartley band of ozone may be derived from simultaneous measurements of the oxygen atmospheric band and infrared atmospheric band volume emission rates independent of knowledge of the ozone density, the solar irradiance, and the ozone absorption cross sections. The heating rates due to key exothermic reactions may be derived directly from appropriate airglow observations independent of the reactant concentrations and the temperature-dependent reaction rates. The accuracy of heating rates derived directly from airglow measurements is also inherently higher than that obtained in standard approaches. We suggest that heating rates derived in this manner be treated as data products and that they be compared with numerical model computations to enhance understanding of atmospheric thermodynamics. An initial comparison of airglow-derived energy deposition rates with deposition rates traditionally computed from numerical models shows agreement to within 20% for the Hartley band of ozone in the lower and upper mesosphere.

  3. HF-induced airglow at magnetic zenith: Thermal and parametric instabilities near electron gyroharmonics

    NASA Astrophysics Data System (ADS)

    Mishin, E. V.; Kosch, M. J.; Pedersen, T. R.; Burke, W. J.

    2005-12-01

    We analyze airglow induced by intense radio waves at the High-frequency Active Auroral Research Program (HAARP) facility for pump frequencies f0 near the second and third electron gyroharmonic (fc). While passing through the double resonance in the weakening ionosphere during heating at f0 ~ 2fc, airglow intensities rose abruptly and remained elevated during four consecutive pulses. During this period both the thermal and parametric instabilities coexisted. Subsequently, the thermal parametric instability was hampered. The effectiveness of heating near the second gyroharmonic is ascribed to specific dispersion characteristics near the double resonance. The observations suggest that Langmuir waves participate in cyclotron acceleration when the local plasma and second gyroharmonic frequencies match. With f0 ~ 3fc the airglow terminated due to the suppression of cyclotron acceleration and parametric decay instability.

  4. Excitation of the Venus night airglow

    NASA Technical Reports Server (NTRS)

    Lawrence, G. M.; Barth, C. A.; Argabright, V.

    1977-01-01

    The strongest spectral features in the Venus night airglow between 3000 and 8000 A are identified as the Herzberg II bands of molecular oxygen. These bands have been produced in a laboratory afterglow by the recombination of oxygen atoms in the presence of carbon dioxide molecules. It is hypothesized that the same mechanism produces this emission in the upper atmosphere of Venus.

  5. Single vs multi-level quenching of the hydroxyl airglow

    NASA Astrophysics Data System (ADS)

    Franzen, Christoph; Espy, Patrick J.; Hibbins, Robert; Djupvik, Anlaug Amanda

    2016-04-01

    The reaction in the upper mesosphere between atomic hydrogen and ozone results in hydroxyl (OH) that is produced in excited vibrational levels 6 through 9. The vibrationally excited OH radiates in a thin (~8 km thick) layer near 87 km, giving rise to the strong near infrared airglow emission that has been used for remote sensing of the mesopause region. The interpretation of the emission relies on accurate knowledge of the population and quenching of the upper states, and open questions remain as to whether the quenching takes place through single- or multi-quantum deactivation. Here we will demonstrate how high quality spectral observations of OH (9,7) and (8,6) airglow emissions are available as background measurements during standard K-band astronomical observations from the Nordic Optical Telescope (18°W, 29°N). These emissions have been analysed to ascertain the quenching of the upper vibrational populations. Together with a steady-state model of these emissions, an estimate of the ratio of single to multi-quantum quenching efficiency and the impact on the populations of the lower vibrational levels will be presented.

  6. Geomagnetically conjugate observations of ionospheric and thermospheric variations accompanied with a midnight brightness wave at low latitudes

    NASA Astrophysics Data System (ADS)

    Fukushima, D.; Shiokawa, K.; Otsuka, Y.; Kubota, M.; Yokoyama, T.; Nishioka, M.; Komonjinda, S.; Yatini, C. Y.

    2014-12-01

    A midnight brightness wave (MBW) is the phenomenon that the OI (630-nm) airglow enhancement propagates poleward once at local midnight. In this study, we first conducted geomagnetically conjugate observations of 630nm airglow for an MBW at conjugate stations. An airglow enhancement which is considered to be an MBW was observed in the 630-nm airglow images at Kototabang, Indonesia (geomagnetic latitude (MLAT): 10.0S) at around local midnight from 1540 to 1730 UT (from 2240 to 2430 LT) on 7 February 2011. This MBW was propagating south-southwestward, which is geomagnetically poleward, with a velocity of 290 m/s. However, similar wave was not observed in the 630-nm airglow images at Chiang Mai, Thailand (MLAT: 8.9N), which is close to being conjugate point of Kototabang. This result indicates that the MBW does not have geomagnetic conjugacy. We simultaneously observed thermospheric neutral winds observed by a co-located Fabry-Perot interferometer at Kototabang. The observed meridional winds turned from northward (geomagnetically equatorward) to southward (geomagnetically poleward) just before the MBW was observed. The bottomside ionospheric heights observed by ionosondes rapidly decreased at Kototabang and slightly increased at Chiang Mai simultaneously with the MBW passage. In the presentation, we discuss the MBW generation by the observed poleward neutral winds at Kototabang, and the cause of the coinciding small height increase at Chiang Mai by the polarization electric field inside the observed MBW at Kototabang.

  7. HiT&MIS: Instrumentation for Auroral and Ionospheric Airglow Studies

    NASA Astrophysics Data System (ADS)

    Hewawasam, K.; Maguire, R.; Chakrabarti, S.; Cook, T.; Baumgardner, J. L.

    2014-12-01

    We have developed a high-throughput imaging spectrograph that uses an echelle grating operating at a high dispersion order to observe extended sources such as atmospheric airglow and auroral emissions at high spectral resolution. Instead of the conventional single slit this instrument uses four with appropriate foreoptics to image a long, narrow field of view of approximately 0.1 × 50 deg. By using interference filters for order sorting, this instrument can simultaneously observe multiple spectral features located anywhere in the visible band (approximately 300 to 1000 nm) at high resolution. The current implementation images the scene at 6 wavelengths (427.8, 486.1, 557.7, 630.0, 656.3 and 777.4 nm), but the flexibility of the design of the instrument allows varying the wavelengths of interest with minimal modifications. We have constructed two spectrographs to be located at different geomagnetic locations. This will enable tomography of atmospheric phenomena for full 3-D rendering of the volume emission. We will combine HiT&MIS data with data from LITES, GROUP-C (on ISS) and other ground based sources such as GIRO, HiTIES, HIRISE and CHIMES along with the 13 all-sky imagers operated by Boston University to form a more complete picture of the ionosphere.This work is supported by the NSF grant AGS1315354

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  9. Vacuum ultraviolet instrumentation for solar irradiance and thermospheric airglow

    NASA Astrophysics Data System (ADS)

    Woods, Thomas N.; Rottman, Gary J.; Bailey, Scott M.; Solomon, Stanley C.

    1993-08-01

    A NASA sounding rocket experiment was developed to study the solar extreme ultraviolet (EUV) spectral irradiance and its effect on the upper atmosphere. Both the solar flux and the terrestrial molecular nitrogen via the Lyman-Birge-Hopfield bands in the far ultraviolet (FUV) were measured remotely from a sounding rocket on October 27, 1992. The rocket experiment also includes EUV instruments from Boston University (Supriya Chakrabarti), but only the National Center for Atmospheric Research (NCAR)/University of Colorado (CU) four solar instruments and one airglow instrument are discussed here. The primary solar EUV instrument is a 1/4 meter Rowland circle EUV spectrograph which has flown on three rockets since 1988 measuring the solar spectral irradiance from 30 to 110 nm with 0.2 nm resolution. Another solar irradiance instrument is an array of six silicon XUV photodiodes, each having different metallic filters coated directly on the photodiodes. This photodiode system provides a spectral coverage from 0.1 to 80 nm with about 15 nm resolution. The other solar irradiance instrument is a silicon avalanche photodiode coupled with pulse height analyzer electronics. This avalanche photodiode package measures the XUV photon energy providing a solar spectrum from 50 to 12,400 eV (25 to 0.1 nm) with an energy resolution of about 50 eV. The fourth solar instrument is an XUV imager that images the sun at 17.5 nm with a spatial resolution of 20 arc-seconds. The airglow spectrograph measures the terrestrial FUV airglow emissions along the horizon from 125 to 160 nm with 0.2 nm spectral resolution. The photon-counting CODACON detectors are used for three of these instruments and consist of coded arrays of anodes behind microchannel plates. The one-dimensional and two-dimensional CODACON detectors were developed at CU by Dr. George Lawrence. The pre-flight and post-flight photometric calibrations were performed at our calibration laboratory and at the Synchrotron Ultraviolet

  10. Vacuum ultraviolet instrumentation for solar irradiance and thermospheric airglow

    NASA Technical Reports Server (NTRS)

    Woods, Thomas N.; Rottman, Gary J.; Bailey, Scott M.; Solomon, Stanley C.

    1993-01-01

    A NASA sounding rocket experiment was developed to study the solar extreme ultraviolet (EUV) spectral irradiance and its effect on the upper atmosphere. Both the solar flux and the terrestrial molecular nitrogen via the Lyman-Birge-Hopfield bands in the far ultraviolet (FUV) were measured remotely from a sounding rocket on October 27, 1992. The rocket experiment also includes EUV instruments from Boston University (Supriya Chakrabarti), but only the National Center for Atmospheric Research (NCAR)/University of Colorado (CU) four solar instruments and one airglow instrument are discussed here. The primary solar EUV instrument is a 1/4 meter Rowland circle EUV spectrograph which has flown on three rockets since 1988 measuring the solar spectral irradiance from 30 to 110 nm with 0.2 nm resolution. Another solar irradiance instrument is an array of six silicon XUV photodiodes, each having different metallic filters coated directly on the photodiodes. This photodiode system provides a spectral coverage from 0.1 to 80 nm with about 15 nm resolution. The other solar irradiance instrument is a silicon avalanche photodiode coupled with pulse height analyzer electronics. This avalanche photodiode package measures the XUV photon energy providing a solar spectrum from 50 to 12,400 eV (25 to 0.1 nm) with an energy resolution of about 50 eV. The fourth solar instrument is an XUV imager that images the sun at 17.5 nm with a spatial resolution of 20 arc-seconds. The airglow spectrograph measures the terrestrial FUV airglow emissions along the horizon from 125 to 160 nm with 0.2 nm spectral resolution. The photon-counting CODACON detectors are used for three of these instruments and consist of coded arrays of anodes behind microchannel plates. The one-dimensional and two-dimensional CODACON detectors were developed at CU by Dr. George Lawrence. The pre-flight and post-flight photometric calibrations were performed at our calibration laboratory and at the Synchrotron Ultraviolet

  11. Earth FUV Dayglow Response to the 20 January 2005 Solar Flare: TIMED and IMAGE Observations

    NASA Astrophysics Data System (ADS)

    Retherford, K. D.; Gladstone, R.; Solomon, S. C.; Immel, T. J.

    2005-05-01

    An X-class solar flare occurred on 20 January 2005 when the TIMED and IMAGE spacecraft were both well positioned to observe the response of Earth's dayglow emission intensity. Brightness enhancements during the flare relative to just before were determined at tangent altitudes of peak emission viewed toward the limb with TIMED. The TIMED observations were made at low solar zenith angles and show flare enhancements of roughly 15%, 30%, 30%, and 60%, respectively, for OI 130.4 nm, OI 135.6 nm, N2 LBH Short, and N2 LBH Long modes of the TIMED/GUVI instrument. However, GUVI observations of HI Lyman-alpha emission brightness do not show a significant brightness change. This lack of change in HI Lyman-alpha dayglow brightness is consistent with no significant change (<2%) in the solar Lyman-alpha flux observed with TIMED/SEE. Enhancements of emissions produced by photodissociation and photoelectron impact excitation sources are studied with IMAGE observations following Immel et al., JGR, 2003. Simulations of dayglow limb profiles to compare with the observations are produced using the NRLMSIS atmosphere model, the IRI90 ionosphere model, the GLOW photoelectron model, and the REDISTER radiative transfer model. The combined datasets enable a better study of the airglow sources most affected by the EUV and x-ray components of solar irradiance variability. We report our preliminary analysis of the response of FUV dayglow emissions to this event.

  12. Functional characteristics of the OGO main body airglow photometer

    NASA Technical Reports Server (NTRS)

    Reed, E. I.; Fowler, W. B.; Blamont, J. E.

    1972-01-01

    The OGO-4 main body airglow photometer used a trialkali cathode photomultiplier to sense light at selected wavelengths between 2500 and 6300A corresponding to important emissions in the aurora and night airglow at emission rates ranging from a few rayleighs to about 200 kilorayleighs. The optical, electronic, and mechanical systems are described in terms of their functional characteristics.

  13. Berkeley extreme-ultraviolet airglow rocket spectrometer - BEARS

    NASA Technical Reports Server (NTRS)

    Cotton, D. M.; Chakrabarti, S.

    1992-01-01

    The Berkeley EUV airglow rocket spectrometer (BEARS) instrument is described. The instrument was designed in particular to measure the dominant lines of atomic oxygen in the FUV and EUV dayglow at 1356, 1304, 1027, and 989 A, which is the ultimate source of airglow emissions. The optical and mechanical design of the instrument, the detector, electronics, calibration, flight operations, and results are examined.

  14. Twilight Intensity Variation of the Infrared Hydroxyl Airglow

    NASA Technical Reports Server (NTRS)

    Lowe, R. P.; Gilbert, K. L.; Niciejewski, R. J.

    1984-01-01

    The vibration rotation bands of the hydroxyl radical are the strongest features in the night airglow and are exceeded in intensity in the dayglow only by the infrared atmospheric bands of oxygen. The variation of intensity during evening twilight is discussed. Using a ground-based Fourier Transform Spectrometer (FTS), hydroxyl intensity measurements as early as 3 deg solar depression were made. Models of the twilight behavior show that this should be sufficient to provide measurement of the main portion of the twilight intensity change. The instrument was equipped with a liquid nitrogen-cooled germanium detector whose high sensitivity combined with the efficiency of the FTS technique permits spectra of the region 1.1 to 1.6 microns at high signal-to-noise to be obtained in two minutes. The use of a polarizer at the entrance aperture of the instrument reduces the intensity of scattered sunlight by a factor of at least ten for zenith observations.

  15. A mesospheric airglow multichannel photometer and an optical method to measure mesospheric AGW intrinsic parameters

    NASA Astrophysics Data System (ADS)

    Mangognia, Anthony; Swenson, Gary; Vargas, Fabio; Liu, Alan

    2016-05-01

    A multichannel photometer (MCP) instrument, designed with filters for three specific airglow emissions, OH Meinel (5-1), (6-2), 840 nm; O2 (b) (0,1), 865 nm; and O(1S), 557.7 nm, as well as background, is used to observe atmospheric wave perturbations to layers in the local zenith with high temporal resolution (∼5 s). By measuring the relative phase of propagating waves through the layers, with known altitude separation, we deduce the vertical wavelength. We describe here the instrument attributes, a unique background subtraction technique, and the validation of a new method for determining intrinsic wave parameters via MCP and imager data that can be taken from various platforms, including ground-based and spacecraft platforms. Vertical wavelengths deduced using this method are in close agreement with those measured using LIDAR temperatures as well as those calculated with the dispersion relation using a combination of all-sky imager (horizontal wavelength) and meteor radar (winds) data.

  16. Astronomical spectra as powerful source for airglow studies

    NASA Astrophysics Data System (ADS)

    Kausch, W.; Noll, S.; Unterguggenberger, S.; Proxauf, B.; Kimeswenger, S.

    2015-03-01

    Light from astronomical objects has to pass the Earth's atmosphere before it reaches ground-based telescopes. Thus, any observation taken with such facilities contains information on the chemical composition and the physical state of the atmosphere. In particular, optical and near-infrared spectra taken with such telescopes are well suited to study various airglow emissions arising in the upper atmosphere thanks to the small field-of-view of the telescopes, large mirror sizes, and the frequent usage of medium to high resolution spectrographs. We study data taken by two frequently used echelle spectrographs from the Very Large Telescope (VLT) of the European Southern Observatory at Cerro Paranal (Chile): UVES, operative since 1999, is a high-resolution (20000 R 110000) instrument covering the wavelength range from 300 to 1100 nm. Hence, several O2 band systems (Herzberg I+II, Chamberlain, atmospheric), the green and red OI lines ( 557 nm; 630 nm), the recently discovered FeO bands ( 550 to 720 nm), NaID ( 589 nm), and all hydroxyl bands up to OH(3-0) can be investigated. The high temporal coverage allows investigations for more than one solar cycle. The X-Shooter instrument is an echelle spectrograph which is able to take medium-resolution (3000 R 18000) spectra from 300 to 2480 nm within one shot. Therefore, it is well suited for a comprehensive study of OH, as it covers all bands with a vibrational level difference 2 (up to OH(9-7)) simultaneously, apart from the previously mentioned other lines and bands. X-Shooter was put into operation in 2009. In this presentation, we will give a review on the available spectra, their quality and time coverage. Moreover, we will illustrate the potential of the data for airglow studies by showing results

  17. Observations of the breakdown of an atmospheric gravity wave near the cold summer mesopause at 54N

    NASA Astrophysics Data System (ADS)

    Hecht, James H.; Fricke-Begemann, Cord; Walterscheid, Richard L.; Höffner, Josef

    2000-03-01

    Recently, it was shown from a single set of airglow/lidar observations in Urbana, Illinois (40N) that some small-scale wave-like structure seen in OH airglow images can be associated with the breakdown, via a convective instability, of an atmospheric gravity wave. A second set of simultaneous airglow/lidar observations, showing wave breakdown, has been obtained over Kühlungsborn, Germany (54N) during a period when noctilucent clouds (NLCs) were also observed. This showed that the wave breakdown process can occur under the same cold, low altitude summer mesopause conditions that support the occurrence of NLCs. This new set of data shows that the first observations were not a unique event, and give credence to the suggestion that some of the small scale structure seen in NLC displays may be due to wave breakdown.

  18. Thermospheric airglow emissions - A comparison of measurements from Atlas-1 and theory

    NASA Technical Reports Server (NTRS)

    Torr, Douglas G.; Torr, Marsha R.; Richards, P. G.

    1993-01-01

    A comprehensive thermospheric model is presently used to derive conditions appropriate to the time of the Atlas-1 Space Shuttle mission, comparing the slant-path intensities thus computed as a function of altitude, latitude, and local time with a dozen major emissions measured in the course of a specific observing sequence. The agreement thus obtained is found to be reasonably good, implying that the major thermospheric airglow-controlling processes are essentially understood.

  19. Mars dayside temperature from airglow limb profiles : comparison with in situ measurements and models

    NASA Astrophysics Data System (ADS)

    Gérard, Jean-Claude; Bougher, Stephen; Montmessin, Franck; Bertaux, Jean-Loup; Stiepen, A.

    The thermal structure of the Mars upper atmosphere is the result of the thermal balance between heating by EUV solar radiation, infrared heating and cooling, conduction and dynamic influences such as gravity waves, planetary waves, and tides. It has been derived from observations performed from different spacecraft. These include in situ measurements of orbital drag whose strength depends on the local gas density. Atmospheric temperatures were determined from the altitude variation of the density measured in situ by the Viking landers and orbital drag measurements. Another method is based on remote sensing measurements of ultraviolet airglow limb profiles obtained over 40 years ago with spectrometers during the Mariner 6 and 7 flybys and from the Mariner 9 orbiter. Comparisons with model calculations indicate that they both reflect the CO_2 scale height from which atmospheric temperatures have been deduced. Upper atmospheric temperatures varying over the wide range 270-445 K, with a mean value of 325 K were deduced from the topside scale height of the airglow vertical profile. We present an analysis of limb profiles of the CO Cameron (a(3) Pi-X(1) Sigma(+) ) and CO_2(+) doublet (B(2) Sigma_u(+) - X(2) PiΠ_g) airglows observed with the SPICAM instrument on board Mars Express. We show that the temperature in the Mars thermosphere is very variable with a mean value of 270 K, but values ranging between 150 and 400 K have been observed. These values are compared to earlier determinations and model predictions. No clear dependence on solar zenith angle, latitude or season is apparent. Similarly, exospheric variations with F10.7 in the SPICAM airglow dataset are small over the solar minimum to moderate conditions sampled by Mars Express since 2005. We conclude that an unidentified process is the cause of the large observed temperature variability, which dominates the other sources of temperature variations.

  20. Magnetic ordering of the polar airglow

    NASA Technical Reports Server (NTRS)

    Frederick, J. E.; Hays, P. B.

    1978-01-01

    The visible airglow experiment on the Atmosphere Explorer-C satellite has gathered sufficient data over the earth's polar regions to allow one to map the geographic distribution of particle precipitation using emissions at 3371 and 5200 A. Both of these features exhibit large variations in space and time. The 3371 A emission of N2(C cubed pi), excited by low energy electrons, indicates substantial energy inputs on the dayside in the vicinity of the polar cusp. More precipitation occurs in the morning than evening for the sample reported here, while the entire night sector between magnetic latitudes 65 and 77.5 deg is subjected to particle fluxes. Regions of enhanced 5200 A emission from N(D-2) are larger in horizontal extent than those at 3371 A. This smearing effect is due to ionospheric motions induced by magnetospheric convection.

  1. Measurement of atomic oxygen and related airglows in the lower thermosphere

    NASA Technical Reports Server (NTRS)

    Thomas, R. J.; Young, R. A.

    1981-01-01

    Instruments on board a sounding rocket were used to make simultaneous observations of atomic oxygen density and airglow emissions between 80 and 120 km. Atomic oxygen was measured with a resonance lamp and was found to have a peak density of 6 x 10 to the 11th at 94 km. Similar structure is seen in the oxygen density profile on both uplegs and downlegs. The following airglow emissions were measured by using vertical-viewing photometers: Herzberg I bands near 300 nm; O(1S) green line at 557.7 nm; background at 566 nm; O2(1 Delta g) bands at 1.27 microns; and OH (X 2 pi) Meinel bands near 1.7 microns.

  2. 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.

  3. Equatorial enhancement of the nighttime OH mesospheric infrared airglow

    NASA Astrophysics Data System (ADS)

    Baker, D. J.; Thurgood, B. K.; Harrison, W. K.; Mlynczak, M. G.; Russell, J. M.

    2007-05-01

    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 (Δv=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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  5. Earth Observation Services Weather Imaging

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Microprocessor-based systems for processing satellite data offer mariners real-time images of weather systems, day and night, of large areas or allow them to zoom in on a few square miles. Systems West markets these commercial image processing systems, which have significantly decreased the cost of satellite weather stations. The company was assisted by the EOCAP program, which provides government co-funding to encourage private investment in, and to broaden the use of, NASA-developed technology for analyzing information about Earth and ocean resources.

  6. HF-enhanced 4278-Å airglow: evidence of accelerated ionosphere electrons?

    NASA Astrophysics Data System (ADS)

    Fallen, C. T.; Watkins, B. J.

    2013-12-01

    We report calculations from a one-dimensional physics-based self-consistent ionosphere model (SCIM) demonstrating that HF-heating of F-region electrons can produce 4278-Å airglow enhancements comparable in magnitude to those reported during ionosphere HF modification experiments at the High-frequency Active Auroral Research Program (HAARP) observatory in Alaska. These artificial 'blue-line' emissions, also observed at the EISCAT ionosphere heating facility in Norway, have been attributed to arise solely from additional production of N2+ ions through impact ionization of N2 molecules by HF-accelerated electrons. Each N2+ ion produced by impact ionization or photoionization has a probability of being created in the N2+(1N) excited state, resulting in a blue-line emission from the allowed transition to its ground state. The ionization potential of N2 exceeds 18 eV, so enhanced impact ionization of N2 implies that significant electron acceleration processes occur in the HF-modified ionosphere. Further, because of the fast N2+ emission time, measurements of 4278-Å intensity during ionosphere HF modification experiments at HAARP have also been used to estimate artificial ionization rates. To the best of our knowledge, all observations of HF-enhanced blue-line emissions have been made during twilight conditions when resonant scattering of sunlight by N2+ ions is a significant source of 4278-Å airglow. Our model calculations show that F-region electron heating by powerful O-mode HF waves transmitted from HAARP is sufficient to increase N2+ ion densities above the shadow height through temperature-enhanced ambipolar diffusion and temperature-suppressed ion recombination. Resonant scattering from the modified sunlit region can cause a 10-20 R increase in 4278-Å airglow intensity, comparable in magnitude to artificial emissions measured during ionosphere HF-modification experiments. This thermally-induced artificial 4278-Å aurora occurs independently of any artificial

  7. Spectroscopy of the Cameron bands in the Mars airglow

    NASA Technical Reports Server (NTRS)

    Conway, R. R.

    1981-01-01

    Mars airglow spectra obtained by the ultraviolet spectrometer on board the Mariner 9 spacecraft were analyzed by using a high-resolution synthesis of the observed emissions. Bright limb observations were made of altitudes between 88 and 180 km of which the brightest features are the carbon monoxide Cameron bands in the wavelength region 1800-2600 A. The shape of these bands cannot be characterized by a single rotational temperature, but is best described by temperatures of 1600 K for lower J values and 10,000 K for higher J values. The observed zenith intensity of 16.7 kR is in good agreement with an excitation theory in which electron-impact dissociation is the most important mechanism. The observations suggest the value of the cross section for this process should be 7 x 10 to the -17th/sq cm. The first negative bands of CO(+) are not identified in the Mariner 9 spectra. This is consistent with the excitation theory for these bands.

  8. Cassini UVIS observations of Titan nightglow spectra

    NASA Astrophysics Data System (ADS)

    Ajello, Joseph M.; West, Robert A.; Gustin, Jacques; Larsen, Kristopher; Stewart, A. Ian F.; Esposito, Larry W.; McClintock, William E.; Holsclaw, Gregory M.; Bradley, E. Todd

    2012-12-01

    In this paper we present the first nightside EUV and FUV airglow limb spectra of Titan showing molecular emissions. The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed photon emissions of Titan's day and night limb-airglow and disk-airglow on multiple occasions, including during an eclipse observation. The 71 airglow observations analyzed in this paper show EUV (600-1150 Å) and FUV (1150-1900 Å) atomic multiplet lines and band emissions arising from either photoelectron induced fluorescence and solar photo-fragmentation of molecular nitrogen (N2) or excitation by magnetosphere plasma. The altitude of the peak UV emissions on the limb during daylight occurred inside the thermosphere at the altitude of the topside ionosphere (near 1000 km altitude). However, at night on the limb, a subset of emission features, much weaker in intensity, arise in the atmosphere with two different geometries. First, there is a twilight photoelectron-excited glow that persists with solar depression angle up to 25-30 degrees past the terminator, until the solar XUV shadow height passes the altitude of the topside ionosphere (1000-1200 km). The UV twilight glow spectrum is similar to the dayglow but weaker in intensity. Second, beyond 120° solar zenith angle, when the upper atmosphere of Titan is in total XUV darkness, there is indication of weak and sporadic nightside UV airglow emissions excited by magnetosphere plasma collisions with ambient thermosphere gas, with similar N2 excited features as above in the daylight or twilight glow over an extended altitude range.

  9. Berkeley extreme-ultraviolet airglow rocket spectrometer: BEARS.

    PubMed

    Cotton, D M; Chakrabarti, S

    1992-09-20

    We describe the Berkeley extreme-UV airglow rocket spectrometer, which is a payload designed to test several thermospheric remote-sensing concepts by measuring the terrestrial O I far-UV and extreme-UV dayglow and the solar extreme-UV spectrum simultaneously. The instrument consisted of two near-normal Rowland mount spectrometers and a Lyman-alpha photometer. The dayglow spectrometer covered two spectral regions from 980 to 1040 A and from 1300 to 1360 A with 1.5-A resolution. The solar spectrometer had a bandpass of 250-1150 A with an ~ 10-A resolution. All three spectra were accumulated by using a icrochannel-plate-intensified, two-dimensional imaging detector with three separate wedge-and strip anode readouts. The hydrogen Lyman-alpha photometer was included to monitor the solar Lyman-alpha irradiance and geocoronal Lyman-alpha emissions. The instrument was designed, fabricated, and calibrated at the University of California, Berkeley and was successfully launched on 30 September 1988 aboard the first test flight of a four-stage sounding rocket, Black Brant XII. PMID:20733778

  10. Observations of the far ultraviolet airflow by the Ultraviolet Limb Imaging experiment on STS-39

    NASA Technical Reports Server (NTRS)

    Budzien, S. A.; Feldman, P. D.; Conway, R. R.

    1994-01-01

    The Ultraviolet Limb Imaging (UVLIM) experiment flew on STS-39 in the spring of 1991 to observe the Earth's thermospheric airglow and included a far ultraviolet (1080-1800 A) spectrometer. We present first results from this spectrometer, including a spectroscopic analysis at 6-A resolution of H, O, N, and N2 dayglow emissions and modeling of the observed limb-scan profiles of dayglow emissions. The observed N2 Lyman-Birge-Hopfield (LBH) emission reflects a vibrational population distribution in the a(1 Pi)(sub g) state that differs significantly from those predicted for direct electron excitation and excitation with cascade from the a('1 Sigma)(sub u)(-) and w(1 Delta)(sub u) states. The vibrational population distribution and LBH brightness suggest a total cascade rate 45% that of direct excitation, in contrast to laboratory measurements. For the first time, pronounced limb brightening is observed in both the N I lambda 1200 limb emission profiles, as expected for emissions excited by N2 dissociation which produces kinetically fast N fragments; however, optically thick components of these features are also observed. Preliminary modeling of the OI lambda 1356, HI lambda 1216, and OI lambda 1304 and OI lambda 1641 emissions agrees to within roughly 10% of the observed limb-scan profiles, but the models underestimate the N2 LBH profiles by a factor of 1.4-1.6, consistent with the inferred cascade effect. Other findings include: an OI lambda 1152/lambda 1356 intensity ratio that is inconsistent with the large cascade contribution to OI lambda 1356 from np 5P states required by laboratory and nightglow observations; nightglow observations of the tropical ultraviolet arcs exhibit a wide range of OI lambda 1356/lambda 1304 intensity ratios and illustrate the complicated observing geometry and radiative transfer effects that must be modeled; and we find a 3-sigma upper limit of 8.5 R to the total LBH vehicle glow emission.

  11. Measurements of the Michigan Airglow Observatory from 1971 to 1973 at Ester Dome Alaska

    NASA Technical Reports Server (NTRS)

    Mcwatters, K. D.; Meriwether, J. W.; Hays, P. B.; Nagy, A. F.

    1973-01-01

    The Michigan Airglow Observatory (MAO) was located at Ester Dome Observatory, College, Alaska (latitude: 64 deg 53'N, longitude: 148 deg 03'W) since October, 1971. The MAO houses a 6-inch Fabry-Perot interferometer, a 2-channel monitoring photometer and a 4-channel tilting filter photometer. The Fabry-Perot interferometer was used extensively during the winter observing seasons of 1971-72 and 1972-73 to measure temperature and mass motions of the neutral atmosphere above approximately 90 kilometers altitude. Neutral wind data from the 1971-72 observing season as measured by observing the Doppler shift of the gamma 6300 A atomic oxygen emission line are presented.

  12. Comparison of Data From Far Ultraviolet Limb Scanning and Imaging Instrumentation Aboard the Advanced Research and Global Observation Satellite (ARGOS)

    NASA Astrophysics Data System (ADS)

    Walker, P. W.; Carruthers, G. R.; Dymond, K. F.; Finch, M. A.; McDonald, S. E.; Nicholas, A. C.; Thonnard, S. E.; Budzien, S. A.; McCoy, R. P.

    2001-05-01

    The ARGOS satellite includes two Naval Research Laboratory experiments that monitor naturally occurring far ultraviolet emissions in the Earth's upper atmosphere. Coincident observations between these two instruments, the Global Imaging Monitor of the Ionosphere (GIMI) and the Low Resolution Airglow and Auroral Spectrograph (LORAAS), have been obtained. The GIMI instrument produces 9 ° x 9 ° limb images with passband coverage between 131 and 200 nm. The LORAAS instrument provides the spectral distribution from 80 to 170 nm for 2.4 ° x 17 ° field of regard. The two instruments are coaligned aboard the spacecraft, aft-looking in the orbital plane. Preliminary comparisons of observations obtained from the imaging and scanning instruments under quiet geomagnetic conditions are reported, including irradiances and spectral distributions. By combining the GIMI data with that from LORAAS, the study of the dynamics of the ionosphere can be expanded to investigate both horizontal and vertical distrubutions and their variances. The improved capability can extend to the study of active periods with highly variable and disturbed ionospheres, and examples are discussed from data acquired during periods of high geomagnetic activity. These results provide the first direct comparison between near simultaneous limb scans and images from ARGOS, and show promise as a validation technique to improve capabilities for the study of ionospheric variability.

  13. Ultraviolet Imaging Telescope (UIT) observations of galaxies

    NASA Technical Reports Server (NTRS)

    Neff, S. G.

    1993-01-01

    Ultraviolet images of several galaxies were obtained during the ASTRO-1 shuttle mission in December, 1990. The images have a FWHM angular resolution of approximately 3 arcsecond and are of circular fields approximately 40 arcminutes in diameter. Most galaxies were observed in at least two and sometimes as many as four broad bands. A very few fields were observed with narrower band filters. The most basic result of these observations is that most systems look dramatically different in the UV from their well-known optical appearances. Preliminary results of these studies will be presented. Information will be available on fields observed by the UTI during the ASTRO 1 mission; when that data becomes public it can be obtained from the NSSDC. The ASTRO observatory is expected to fly again in 1994 with approximately half of the observing time from that mission devoted to guest observers. The Ultraviolet Imaging telescope is extremely well suited for galaxy studies, and the UIT term is interested in encouraging a wide range of scientific studies by guest observers. Ultraviolet Imaging telescope is extremely well suited for galaxy studies, and the UIT team is interested in encouraging a wide range of scientific studies by guest observers.

  14. Observations of Dynamics in the High Arctic Mesopause Region and Thermosphere

    NASA Astrophysics Data System (ADS)

    Ward, William E.; Meek, Chris; Manson, Alan; Hocking, Wayne; Kristoffersen, Samuel; Wu, Qian; Vail, Christopher; Shepherd, Marianna

    2016-07-01

    The Dynamics of the Neutral Thermosphere project is a three site, multiple instrument observatory. The instruments are located in the Canadian Arctic at Resolute Bay (75 N, 95 W), Eureka (80 N, 85 W at the Polar Environment Atmospheric Research Laboratory) and Yellowknife (62 N, 114 W)and include meteor radars, high resolution interferometers, and all sky imagers. Measurements include wind, temperature and airglow irradiance at both sites. Inter-instrument and inter-site comparisons of time series are being undertaken and provide insights into the dynamical processes in the high Arctic mesopause region and thermosphere, and information on the various observing techniques. Differences between the daily wind variations are seen between the mesopause region and thermosphere. Studies are under way, to determine whether common tidal and gravity wave signatures can be observed at both sites and in the mesopause region and thermosphere. Airglow irradiance, winds and temperatures are observed with several different instruments and comparisons between the associated time series are revealing the consequences of the different observing processes. For example, Doppler shift wind measurements in airglow using interferometers are irradiance weighted averages of the wind in each airglow layer whereas the meteor radar provide wind profiles. Comparisons between the winds measured by these techniques do not always agree to the extent expected and detailed examinations of whether weighted averages of the meteor radar winds improve the comparisons are being undertaken. Irradiance time series taken with the all sky imagers, interferometers and a Spectral Airglow Temperature Imager (SATI) are being combined to provide more extensive coverage of the mesopause region. This paper will describe the instrument complement and the initial results of these comparisons.

  15. A study of oxygen 6300 Å airglow production through chemical modification of the nighttime ionosphere

    NASA Astrophysics Data System (ADS)

    Semeter, Joshua; Mendillo, Michael; Baumgardner, Jeffrey; Holt, John; Hunton, Donald E.; Eccles, Vincent

    1996-09-01

    The Release Experiments to Derive Airglow Inducing Reactions (RED AIR) conducted on April 3, 1989, and December 6, 1991, offer a unique set of observations for studying the specific processes associated with the production of the O(3P--1D) emission at 6300 Å. In these experiments, sounding rockets were used to place equal quantities of CO2 above and below hmax of the nocturnal F region. CO2 leads to 6300 Å emission by a three-step process: (1) CO2+O+->O2++CO, (2) O2++e-->O*+O, (3)O*->O+hν6300. Direct measurements of plasma parameters and indirect measurements of the neutral atmosphere densities were used in conjunction with the Fluid Element Simulation (FES) computer code to model the temporal and spatial evolution of the observed 6300 Å airglow enhancement and accompanying plasma depletion. Using the currently accepted set of reaction rates relevant to F region chemistry, the quantum yield of O(1D) from reaction (2) was found to have a mild altitude dependence, decreasing by 16% from 275 to 350 km. Since the initial vibrational distribution of the nascent O2+ was the same for the two releases, this result implies an altitude dependence in the quenching of O2+ vibrational states. Building on previous evidence that O2+ is vibrationally excited in the nighttime thermosphere, we further conclude that this vibrational distribution is altitude dependent. In terms of 6300 Å airglow production, the effect is manifested in an altitude dependence of f(1D). Additionally, quenching by O(3P) was found to contribute very little to the depopulation of the nascent O(1D), with Q0=0 giving the best fit to the RED AIR observations.

  16. WIND, FERIX-2 and ISUAL F-region imaging: Ionospheric Observation Campaigns over Japan in 2007

    NASA Astrophysics Data System (ADS)

    Yamamoto, M.; Watanabe, S.; Ono, T.; Abe, T.; Yamamoto, M.; Adachi, T.; Saito, A.; Chen, A.; Hsu, R.; Bernhardt, P.

    2007-12-01

    In the middle/low latitude ionosphere, coupling processes between plasma and neutral atmosphere is important, which is a key to understand ionospheric structures of the spatial scale of 10-1000km. Under international collaboration between scientists from Japan, Taiwan and USA, we are now conducting number of observation campaigns over Japan region. WIND (Wind measurement for Ionized and Neutral atmospheric Dynamics study) is a F-region rocket experiment to study neutral-plasma coupling processes. ISAS/JAXA successfully launched the S-520-23 sounding rocket from Uchinoura Space Center on September 2, 2007. The rocket was equipped with in-situ instruments for plasma-parameters. The Li-release experiment was conducted at the rocket downleg to measure the neutral wind. A dual-band beacon (DBB) transmitter was on board of the rocket, and we received the signal at five stations including one boat under the rocket trajectory. FERIX-2 (F- and E-Region Ionosphere Coupling Study-2) is multi-radar experiment to reveal F-region and E- region coupling processes in the ionosphere. Simultaneous measurement of F-region and E-region FAIs with the MU radar and a portable VHF radar obtained much data showing the coupling through geomagnetic field line. In parallel to these observations we conducted limb imaging of the airglow in the F-region by means of ISUAL on the FORMOSAT-2 satellite in December 2006 and June 2007. Data from FORMOSAT-3/COSCMIC satellites are valuable to support these observations. In the presentation we will overview preliminary results from these observation campaigns, and discuss future collaboration for the study of middle-low latitude ionosphere.

  17. Spaced sensor measurements of artificial airglow emission at 630 nm of ionosphere caused by ``Sura'' facility radiation in November 2013

    NASA Astrophysics Data System (ADS)

    Nasyrov, Igor; Grach, Savely; Gumerov, Rustam; Shindin, Alexey; Kogogin, Denis; Dementiev, Vladislav

    Some first results on simultaneous observation artificial airglow emission at 630 nm during HF pumping of the ionosphere by “Sura” facility from two spatial situated experimental sites are reported. The measurements of artificial airglow are usually conducted in red and green lines of atomic oxygen (the radiation of levels O((1) D) and O((1) S) under their excitation by electronic impact) with wave lengths of 630 and 557.7 nm and excitation energy of 1.96 and 4.17 eV accordingly. An enhancement of airglow intensity in the red line is related at present to the electron heating by powerful radio waves. The idea of the experiment was to estimate the heated volume three-dimensional structure and drift motion one. The experiment was carried out in November 2013 at the “Sura” radio facility, situated near Nizhny Novgorod, Russia (geographical coordinates 56.13(o) N, 46.10(o) E, geomagnetic field declination and inclination are ˜ 10.0(o) east and ˜ 71.5(o) , respectively). Conditions of ionosphere were checked by means of "Cady" ionosonde during “Sura” runs. According to the ionospheric conditions, on the 7(th) of November the “Sura” facility operated at frequency 4.540 MHz. At this frequency the effective radiated power was about 120MW. The HF beam width at the “Sura” facility is ˜ 12(o) . A square wave pump modulation of 5 min on, 5 min off, was used. Measurements were carried out in the period from 14:40 to 17:30 UTC. Optical imaging was performed on two spatial experimental sites: “Vasilsursk” (situated about 500 m from antenna system of “Sura” facility); “Raifa” (situated about 170 km from “Sura” facility at the Magnetic Observatory of Kazan Federal University, geographical coordinates 55.93(o) N, 48.75(o) E). They both were fitted out Peltier-cooled front-illuminated bare CCD cameras with 16-bit slow-scan read-out (S1C3). On “Vasilsursk” site the images were binned down to 256× 256 pixels in addition to cooling, in order

  18. IMAGE-POLAR Concurrent Plasmapause Observations

    NASA Technical Reports Server (NTRS)

    Adrian, M. L.; Gallagher, D. L.; Craven, P. D.

    2004-01-01

    Two critical issues that influence the quantitative scientific value of the IMAGE Ultraviolet Camera (EUV) are: (1) the accuracy with which EUV imaging can be used to determine the position/location of the plasmapause; and (2) the sensitivity threshold of the EUV instrument. These issues are addressed through analysis of concurrent observations of the plasmasphere/plasmapause made remotely using IMAGE EUV and in-situ with the Polar/TIDE/EFI instruments. Preliminary results are presented with regards to the validity of the extraction of the plasmapause using EUV and initial in-flight, in-situ estimates of the EUV sensitivity threshold.

  19. Dynamic image fusion and general observer preference

    NASA Astrophysics Data System (ADS)

    Burks, Stephen D.; Doe, Joshua M.

    2010-04-01

    Recent developments in image fusion give the user community many options for ways of presenting the imagery to an end-user. Individuals at the US Army RDECOM CERDEC Night Vision and Electronic Sensors Directorate have developed an electronic system that allows users to quickly and efficiently determine optimal image fusion algorithms and color parameters based upon collected imagery and videos from environments that are typical to observers in a military environment. After performing multiple multi-band data collections in a variety of military-like scenarios, different waveband, fusion algorithm, image post-processing, and color choices are presented to observers as an output of the fusion system. The observer preferences can give guidelines as to how specific scenarios should affect the presentation of fused imagery.

  20. The D-Region Ledge at Nighttime: Why are Elves Collocated with the OH Meinel Band Airglow Layer?

    NASA Astrophysics Data System (ADS)

    Wu, Y. J.; Williams, E. R.; Hsu, R. R.

    2014-12-01

    The Imager of Sprite and Upper Atmosphere Lightning (ISUAL) onboard the Taiwanese satellite Formosat-2 has continuously observed transient luminous events (TLEs) within the +/-60 degree range of latitude for a decade since May 2004. The lightning electromagnetic pulse is responsible for Elves , the dominate TLE type which accounts for approximately 80% of the total TLE count according to the ISUAL global survey. By analyzing the limb-viewed images with a wavelength filter of 622.8-754nm, 72% of elves are found to be 'glued' to the OH Meinel band (~630nm) nightglow layer within its thickness of 8km, with the OH layer normally at an altitude of 87 km (Huang et al., 2010).This collocation of elves and airglow layer is frequently dismissed as coincidence, since the physical mechanisms for the formation of the two optical phenomena are macroscopically quite different. However, a common ingredient in the atmospheric chemistry is monatomic oxygen. O is needed to make O3 and ultimately hydroxyl OH, the main radiative species of the airglow layer. O is also needed to form nitric oxide NO, the species with the lowest known ionization potential (9.26 eV) in the D-region. Thomas (1990) has documented steep increases in O concentration in the 83-85 km altitude range and Hale (1985) has found steep increases in electrical conductivity in the 84-85 km range, both with rocket measurements. A great simplification of the nighttime ionosphere is the presence of a single photon energy—10.2 eV—Lyman-α, originating in monatomic H in the Earth's geocorona. A simple Chapman layer calculation for the altitude of maximum photo-dissociation of O2, using the measured absorption cross-section of O2 at the Lyman-α energy, shows an altitude of maximum O production at 85 km. Elve emission in the nitrogen first positive band is enhanced by the presence of free electrons from ionized NO, but too large a conductivity will lead to the exclusion of the radiation field from the lightning return

  1. Quantification of heterogeneity observed in medical images

    PubMed Central

    2013-01-01

    Background There has been much recent interest in the quantification of visually evident heterogeneity within functional grayscale medical images, such as those obtained via magnetic resonance or positron emission tomography. In the case of images of cancerous tumors, variations in grayscale intensity imply variations in crucial tumor biology. Despite these considerable clinical implications, there is as yet no standardized method for measuring the heterogeneity observed via these imaging modalities. Methods In this work, we motivate and derive a statistical measure of image heterogeneity. This statistic measures the distance-dependent average deviation from the smoothest intensity gradation feasible. We show how this statistic may be used to automatically rank images of in vivo human tumors in order of increasing heterogeneity. We test this method against the current practice of ranking images via expert visual inspection. Results We find that this statistic provides a means of heterogeneity quantification beyond that given by other statistics traditionally used for the same purpose. We demonstrate the effect of tumor shape upon our ranking method and find the method applicable to a wide variety of clinically relevant tumor images. We find that the automated heterogeneity rankings agree very closely with those performed visually by experts. Conclusions These results indicate that our automated method may be used reliably to rank, in order of increasing heterogeneity, tumor images whether or not object shape is considered to contribute to that heterogeneity. Automated heterogeneity ranking yields objective results which are more consistent than visual rankings. Reducing variability in image interpretation will enable more researchers to better study potential clinical implications of observed tumor heterogeneity. PMID:23453000

  2. Fixing Images Observation Dates Thanks to Asteroids

    NASA Astrophysics Data System (ADS)

    Derriere, S.

    2015-09-01

    An important piece of metadata for any astronomical image is the date and time at which it was observed (and the exposure time). Unfortunately, the values of the observation epoch found in the FITS headers of digitized photographic plates, for example, are not always accurate. There can be many different sources of error: mistakes in the original observation log, errors when converting between different dates and time format (calendar date, Julian days, decimal years, etc.). We present in this paper an analysis of the different values that can be found for the observation epoch of several image sets in various metadata sources. We show how the presence of known asteroids in the field of view can be used to recover the correct time values with a good accuracy.

  3. Modeling of Na airglow emission and first results on the nocturnal variation at midlatitude

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    A model for sodium airglow emission is developed by incorporating all the known reaction mechanisms. The neutral, ionic, and photochemical mechanisms are successfully implemented into this model. The values of reaction rate coefficients are based upon the theoretical calculations as well as from experimental observations. The densities of major species are calculated using the continuity equations, whereas for the minor, intermediating, and short-lived species steady state approximation method is used. The modeled results are validated with the rocket, lidar, and photometer observations for a branching ratio of 0.04 for the production of Na(2P) in the reaction NaO + O → Na(2P, 2S). The inputs have been obtained from other physics-based models and ground- and satellite-based observations to give the combined volume emission rate (VER) of Na airglow between 80 and 110 km altitude. In the present study, the model is used to understand the nocturnal variation of Na VER during the solstice conditions. The model results suggest a variation of peak emission layer between 85 and 90 km during summer solstice condition, indicating a lower value of peak emission rate during summer solstice. The emission rates bear a strong correlation with the O3 density during summer solstice, whereas the magnitude of VER follows the Na density during winter solstice. The altitude of peak VER shows an upward shift of 5 km during winter solstice.

  4. Antarctic Wave Dynamics Mystery Discovered by Lidar, Radar and Imager

    NASA Astrophysics Data System (ADS)

    Chen, Cao; Chu, Xinzhao; Fong, Weichun; Lu, Xian; McDonald, Adrian J.; Pautet, Dominique; Taylor, Mike

    2016-06-01

    Since the start of the McMurdo Fe lidar campaign, largeamplitude (~±30 K), long-period (4 to 9 h) waves with upward energy propagating signatures are frequently observed in the MLT temperatures. Despite its frequent appearance, such type of wave was neither widely observed nor well understood in the past. At McMurdo (77.8°S, 166.7°E), the simultaneous observations of such waves using lidar, radar and airglow imager can provide 3-D intrinsic wave-propagation properties, which are greatly needed for understanding their sources and potential impacts. This study presents the first coincident observation of these 4-9 h waves by lidar, radar and airglow imager in the Antarctic mesopause region.

  5. Imaging radar observations of frozen Arctic lakes

    NASA Technical Reports Server (NTRS)

    Elachi, C.; Bryan, M. L.; Weeks, W. F.

    1976-01-01

    A synthetic aperture imaging L-band radar flown aboard the NASA CV-990 remotely sensed a number of ice-covered lakes about 48 km northwest of Bethel, Alaska. The image obtained is a high resolution, two-dimensional representation of the surface backscatter cross section, and large differences in backscatter returns are observed: homogeneous low returns, homogeneous high returns and/or low returns near lake borders, and high returns from central areas. It is suggested that a low return indicates that the lake is frozen completely to the bottom, while a high return indicates the presence of fresh water between the ice cover and the lake bed.

  6. Granular convection observed by magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Ehrichs, E. E.; Jaeger, H. M.; Karczmar, Greg S.; Knight, James B.; Kuperman, Vadim Yu.; Nagel, Sidney R.

    1995-03-01

    Vibrations in a granular material can spontaneously produce convection rolls reminiscent of those seen in fluids. Magnetic resonance imaging provides a sensitive and noninvasive probe for the detection of these convection currents, which have otherwise been difficult to observe. A magnetic resonance imaging study of convection in a column of poppy seeds yielded data about the detailed shape of the convection rolls and the depth dependence of the convection velocity. The velocity was found to decrease exponentially with depth; a simple model for this behavior is presented here.

  7. Granular convection observed by magnetic resonance imaging

    SciTech Connect

    Ehrichs, E.E.; Jaeger, H.M.; Knight, J.B.; Nagel, S.R.; Karczmar, G.S.; Kuperman, V.Yu.

    1995-03-17

    Vibrations in a granular material can spontaneously produce convection rolls reminiscent of those seen in fluids. Magnetic resonance imaging provides a sensitive and noninvasive probe for the detection of these convection currents, which have otherwise been difficult to observe. A magnetic resonance imaging study of convection in a column of poppy seeds yielded data about the detailed shape of the convection rolls and the depth dependence of the convection velocity. The velocity was found to decrease exponentially with depth; a simple model for this behavior is presented here. 31 refs., 4 figs.

  8. Correlation of 1.65 and 2.15 micron airglow emissions

    NASA Technical Reports Server (NTRS)

    Kieffaber, L. M.

    1974-01-01

    The intense infrared airglow is due primarily to vibration-rotation bands of the OH molecule. This airglow has been observed with a 24-in. scanning photometer at two wavelengths. Narrow-band interference filters are used to limit observations to the (9,7) band at 2.15 microns and the (4,2) and (5,3) bands at 1.65 microns. If OH emission results from creation of the excited OH molecule in the v = 9 vibrational state and subsequent cascading through lower vibrational levels, the 1.65 and 2.15 micron radiation will be well correlated in space and time. However, if several mechanisms are involved in producing OH in a variety of initial excitation levels, there is no reason to expect good correlation. Sky maps obtained simultaneously at 1.65 and 2.15 microns show strongly correlated intensity fluctuations. Quantitative analysis of these maps and other investigations of smaller areas of the sky yield correlation coefficients typically in excess of 0.8.

  9. The Terrestrial O2(1delta) 1.27 micron Airglow Emissions

    NASA Astrophysics Data System (ADS)

    Smith, D.; Yee, J.; Zhu, X.; Mlynczak, M.; Russell, J.; Skinner, W.

    2007-12-01

    The O2(1Δ) 1.27 micron emission is one of the brightest airglow emissions observed in the Earth airglow spectrum and provides an ideal light source for passively sensing the atmosphere. It is known that the excited O2(1Δ) molecules in the daytime are produced by ozone photolysis by solar UV radiation. Its measured emission rates have thus been used to obtain the abundances of ozone. The exact night time excitation mechanisms, however, are still not well-understood. However, atomic oxygen recombination and oxidation of vibrationally excitation OH have been proposed. Observations by instruments onboard TIMED have provided a unique opportunity to examine the spatial and temporal morphology of this emission and its excitation mechanisms. We will use the O2(1Δ) and OH(v) measurements by SABER and O2(1Σ) measurements by TIDI to investigate the O2(1Δ) excitation mechanisms. In addition, because of its relatively long chemical relaxation time, the O2(1Δ), could potentially not be in the steady-state chemical balance. In this paper, we will discuss the importance of this effect and its impact on the utility of this emission for composition retrievals (i.e. ozone and atomic oxygen).

  10. Imaging radar observations of Askja Caldera, Iceland

    NASA Technical Reports Server (NTRS)

    Malin, M. C.; Evans, D.; Elachi, C.

    1978-01-01

    A 'blind' test involving interpretation of computer-enhanced like- and cross-polarized radar images is used to evaluate the surface roughness of Askja Caldera, a large volcanic complex in central Iceland. The 'blind' test differs from earlier analyses of radar observations in that computer-processes images and both qualitative and quantitative analyses are used. Attention is given to photogeologic examination and subsequent survey-type field observations, along with aerial photography during the field trip. The results indicate that the 'blind' test of radar interpretation of the Askja volcanic area can be considered suitable within the framework of limitations of radar data considered explicitly from the onset. The limitations of the radar techniques can be eliminated by using oblique-viewing conditions to remove geometric distortions and slope effects.

  11. Ground network observations of the thermosphere and the mesosphere by the Optical Mesosphere Thermosphere Imagers (OMTIs)

    NASA Astrophysics Data System (ADS)

    Shiokawa, Kazuo; Otsuka, Yuichi

    The Solar-Terrestrial Environment Laboratory, Nagoya University, has operated the Optical Mesosphere Thermosphere Imagers (OMTIs) since 1998. The OMTIs consist of 13 all-sky cooled-CCD imagers, four Fabry-Perot interferometers (FPIs), three meridian scanning pho-tometers, and four airglow temperature photometers. They measure two-dimensional pattern, Doppler wind, and temperature through airglow emissions from oxygen (wavelength: 557.7 nm) and OH (near infrared band) in the mesopause region (80-100 km) and from oxygen (630.0 nm) in the thermosphere/ionosphere (200-300 km). The OMTIs are in automatic operation at Norway, Australia, Indonesia, far-eastern Russia, four stations in Japan, and two stations in Canada. In 2010, three Fabry-Perot interferometers will be installed in Thailand, Indonesia, and Australia, to measure thermospheric neutral wind pattern at two pairs of geomagnetic conjugate stations at low latitudes. In this paper, we show some recent results obtained by OMTIs particularly for the dynamics of the medium-scale traveling ionospheric disturbances in the subauroral and equatorial latitudes.

  12. Correlation and Imaging of Space VLBI Observations

    NASA Astrophysics Data System (ADS)

    Romney, J. D.

    1995-05-01

    Space VLBI observations challenge conventional VLBI data-analysis systems and techniques in several areas. The correlator must obtain and evaluate an ephemeris for an orbiting ``station'' which is not fixed on the surface of the earth. The geometric delay, and its derivatives, for this element can exceed those for terrestrial stations by an order of magnitude. Imperfect knowledge of the orbit requires that the output data flow be sufficient to preserve unusually wide windows in residual delay and fringe rate. And, at least for the current generation of Space VLBI missions, the spacecraft have no on-board precision frequency standard; the phase-transfer process from a frequency standard on the ground is accompanied by errors which must be corrected in the correlator. Imaging of observations involving an orbiting element must contend with gaps in the (u,v) plane coverage for many cases of the orbit and source geometry. Projected baselines to the orbiting element change significantly more rapidly than terrestrial baselines during perigee passage of the spacecraft. Self-calibration techniques are complicated by the facts that all measurements in many regions of the (u,v) plane involve baselines to the single orbiting antenna, and that their residual delay and fringe rate may be subject to short-term variations. Since the current generation of Space VLBI missions have relatively small antennas, observations of weaker sources will be limited to sparse arrays comprising only the largest available radio telescopes on the ground, and interpretation of the results may require sophisticated image model-fitting software. NRAO's participation in the VSOP and Radioastron missions includes programs to modify the VLBA correlator and the AIPS imaging system to meet these requirements. Also included is a user-support program, to provide expert assistance in data analysis to Space VLBI observers, at a level similar to the support NRAO currently provides for ground-based VLBI

  13. Contributions of the OH airglow to space object irradiance

    NASA Astrophysics Data System (ADS)

    Gruninger, John; Duff, James W.; Brown, James H.

    2007-10-01

    We investigated the contributions of the hydroxyl (OH) airglow to the illumination of resident space objects. During nighttime, in a moonless sky, the airglow is the largest contributor to the sky brightness in the visible (vis), the near-infrared (NIR) and short-wave infrared (SWIR) spectral region. The dominant contributors to the airglow are vibrationally excited hydroxyl radicals, OH(ν). The radicals are formed in vibrational states up to υ=9 by the reaction of hydrogen atoms with ozone. The strong emissions, known as Meinel emissions, are sequences with σν= 1-6. Emissions with υ = 3, 4, 5 and 6 occur in the visible and NIR between .4 and 1.0 µm. From 1.0 to 2.5 µm there are very strong emissions from the δν= 2 sequences. The σν= 1 emissions extend into the thermal infrared to 4.5 μm. In this work, we considered four band passes, a vis-NIR band pass, two SABER band passes centered at 1.6 and 2.0 μm, respectively, and a broad band pass around 2.7 µm. SAMM2 was utilized to compute spectra and line of sight radiances. We used line of sight (LOS) radiances to compute the irradiance on a space object that was taken as a flat plate with a Lambertian surface reflectance. Profiles of irradiance versus orientation were calculated. The OH airglow will illuminate a facet even if it is pointing somewhat upward. However, the irradiance in the 2.7 μm band pass comes almost entirely from the atmosphere in the low altitude and the earth emission.

  14. First Light from Triple-Etalon Fabry-Perot Interferometer for Atmospheric OI Airglow (6300 A)

    NASA Astrophysics Data System (ADS)

    Watchorn, S.; Noto, J.; Pedersen, T.; Betremieux, Y.; Migliozzi, M.; Kerr, R. B.

    2006-05-01

    Scientific Solutions, Inc. (SSI) has developed a triple-etalon Fabry-Perot interferometer (FPI) to observe neutral winds in the ionosphere by measuring neutral oxygen (O I) emission at 630.0 nm during the day. This instrument is to be deployed in the SSI airglow building at the Cerro Tololo observatory (30.17S 70.81W) in Chile, in support of the Comm/Nav Outage Forecast System (C/NOFS) project. Post-deployment observation will be made in conjunction with two other Clemson University Fabry-Perots in Peru, creating a longitudinal chain of interferometers for thermospheric observations. These instruments will make autonomous day and night observations of thermospheric dynamics. Instruments of this type can be constructed for a global chain of autonomous airglow observatories. The FPI presented in this talk consists of three independently pressure-controlled etalons, fed collimated light by a front optical train headed by an all-sky lens with a 160-degree field of view. It can be controlled remotely via a web-based service which allows any internet-connected computer to mimic the control computer at the instrument site. In fall 2005, the SSI system was first assembled at the Millstone Hill Observatory in Westford, Massachusetts, and made day and evening observations. It was then moved to the High-frequency Active Auroral Research Project (HAARP) site in Gakona, Alaska, to participate in joint optical/ionospheric heating campaigns. Additionally, natural airglow observations were made, both locally and remotely via the internet from Massachusetts. The Millstone and HAARP observations with two etalons yielded strong 630-nm atmospheric Fraunhofer absorption lines, with some suggestion of the Ring effect. By modeling the atmospheric absorption line as the constant times the corresponding solar absorption -- itself modeled as a Gaussian plus a polynomial -- the absorption feature is subtracted, leaving only the emission feature. Software ring-summing tools developed at the

  15. Large storms: Airglow and related measurements. VLF observations, volume 4

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The data presented show the typical values and range of ionospheric and magnetospheric characteristics, as viewed from 1400 km with the ISIS 2 instruments. The definition of each data set depends partly on geophysical parameters and partly on satellite operating mode. Preceding the data set is a description of the organizational parameters and a review of the objectives and general characteristics of the data set. The data are shown as a selection from 12 different data formats. Each data set has a different selection of formats, but uniformity of a given format selection is preserved throughout each data set. Each data set consists of a selected number of passes, each comprising a format combination that is most appropriae for the particular data set. Description of ISIS 2 instruments are provided.

  16. Polarization observations with the Cosmic Background Imager.

    PubMed

    Readhead, A C S; Myers, S T; Pearson, T J; Sievers, J L; Mason, B S; Contaldi, C R; Bond, J R; Bustos, R; Altamirano, P; Achermann, C; Bronfman, L; Carlstrom, J E; Cartwright, J K; Casassus, S; Dickinson, C; Holzapfel, W L; Kovac, J M; Leitch, E M; May, J; Padin, S; Pogosyan, D; Pospieszalski, M; Pryke, C; Reeves, R; Shepherd, M C; Torres, S

    2004-10-29

    Polarization observations of the cosmic microwave background with the Cosmic Background Imager from September 2002 to May 2004 provide a significant detection of the E-mode polarization and reveal an angular power spectrum of polarized emission showing peaks and valleys that are shifted in phase by half a cycle relative to those of the total intensity spectrum. This key agreement between the phase of the observed polarization spectrum and that predicted on the basis of the total intensity spectrum provides support for the standard model of cosmology, in which dark matter and dark energy are the dominant constituents, the geometry is close to flat, and primordial density fluctuations are predominantly adiabatic with a matter power spectrum commensurate with inflationary cosmological models. PMID:15472038

  17. Localized polar cap flow enhancement tracing using airglow patches: Statistical properties, IMF dependence, and contribution to polar cap convection

    NASA Astrophysics Data System (ADS)

    Zou, Ying; Nishimura, Yukitoshi; Lyons, Larry R.; Shiokawa, Kazuo; Donovan, Eric F.; Ruohoniemi, J. Michael; McWilliams, Kathryn A.; Nishitani, Nozomu

    2015-05-01

    Recent radar observations have suggested that polar cap flows are highly structured and that localized flow enhancements can lead to nightside auroral disturbances. However, knowledge of these flows is limited to available echo regions. Utilizing wide spatial coverage by an all-sky imager at Resolute Bay and simultaneous Super Dual Auroral Radar Network measurements, we statistically determined properties of such flows and their interplanetary magnetic field (IMF) dependence. We found that narrow flow enhancements are well collocated with airglow patches with substantially larger velocities (≥200 m/s) than the weak large-scale background flows. The flow azimuthal widths are similar to the patch widths. During the evolution across the polar cap, the flow directions and speeds are consistent with the patch propagation directions and speeds. These correspondences indicate that patches can optically trace localized flow enhancements reflecting the flow width, speed, and direction. Such associations were found common (~67%) in statistics, and the typical flow speed, propagation time, and width within our observation areas are 600 m/s, tens of minutes, and 200-300 km, respectively. By examining IMF dependence of the occurrence and properties of these flows, we found that they tend to be observed under By-dominated IMF. Flow speeds are large under oscillating IMF clock angles. Localized flow enhancements are usually observed as a channel elongated in the noon-midnight meridian and directed toward premidnight (postmidnight) for +By (-By). The potential drops across localized flow enhancements account for ~10-40% of the cross polar cap potential, indicating that they significantly contribute to polar cap plasma transport.

  18. Solar EUV/UV and equatorial airglow measurements from San Marco-5

    NASA Technical Reports Server (NTRS)

    Schimdtke, G.; Doll, H.; Wita, C.; Chakrabarti, S.

    1991-01-01

    Preliminary results of the solar flux measurements performed by the Airglow-Solar Spectrometer Instrument (ASSI) aboard the San Marco-5 satellite in March-December 1988 are presented. Emphasis is placed on the in-flight performance of the ASSI, its in-flight calibration, and the planned scheme of the airglow modelling.

  19. Post sunset behavior of the 6300 A atomic oxygen airglow emission

    NASA Technical Reports Server (NTRS)

    Smith, R. E.

    1976-01-01

    A theoretical model of the 6300 A OI airglow emission was developed based on the assumptions that both the charged and neutral portions of the Earth's upper atmosphere are in steady state conditions of diffusive equilibrium. Intensities of 6300 A OI emission line were calculated using electron density true height profiles from a standard C-4 ionosonde and exospheric temperatures derived from Fabry-Perot interferometer measurements of the Doppler broadened 6300 A emission line shape as inputs to the model. Reaction rate coefficient values, production mechanism efficiencies, solar radiation fluxes, absorption cross sections, and models of the neutral atmosphere were varied parametrically to establish a set of acceptable inputs which will consistently predict 6300 A emission intensities that closely agree with intensities observed during the post-sunset twilight period by an airglow observatory consisting of a Fabry-Perot interferometer and a turret photometer. Emission intensities that can only result from the dissociative recombination of molecular oxygen ions were observed during the latter portion of the observational period. Theoretical calculations indicate that contamination of the 6300 A OI emission should be on the order of or less than 3 percent; however, these results are very sensitive to the wavelengths of the individual lines and their intensities relative to the 6300 A OI intensity. This combination of a model atmosphere, production mechanism efficiencies, and quenching coefficient values was used when the dissociative photoexcitation and direct impact excitation processes were contributing to the intensity to establish best estimates of solar radiation fluxes in the Schumann--Runge continuum and associated absorption cross sections. Results show that the Jacchia 1971 model of the upper atmosphere combined with the Ackerman recommended solar radiation fluxes and associated absorption cross sections produces theoretically calculated intensities that more

  20. Bayesian Analysis Of HMI Solar Image Observables And Comparison To TSI Variations And MWO Image Observables

    NASA Astrophysics Data System (ADS)

    Parker, D. G.; Ulrich, R. K.; Beck, J.

    2014-12-01

    We have previously applied the Bayesian automatic classification system AutoClass to solar magnetogram and intensity images from the 150 Foot Solar Tower at Mount Wilson to identify classes of solar surface features associated with variations in total solar irradiance (TSI) and, using those identifications, modeled TSI time series with improved accuracy (r > 0.96). (Ulrich, et al, 2010) AutoClass identifies classes by a two-step process in which it: (1) finds, without human supervision, a set of class definitions based on specified attributes of a sample of the image data pixels, such as magnetic field and intensity in the case of MWO images, and (2) applies the class definitions thus found to new data sets to identify automatically in them the classes found in the sample set. HMI high resolution images capture four observables-magnetic field, continuum intensity, line depth and line width-in contrast to MWO's two observables-magnetic field and intensity. In this study, we apply AutoClass to the HMI observables for images from May, 2010 to June, 2014 to identify solar surface feature classes. We use contemporaneous TSI measurements to determine whether and how variations in the HMI classes are related to TSI variations and compare the characteristic statistics of the HMI classes to those found from MWO images. We also attempt to derive scale factors between the HMI and MWO magnetic and intensity observables. The ability to categorize automatically surface features in the HMI images holds out the promise of consistent, relatively quick and manageable analysis of the large quantity of data available in these images. Given that the classes found in MWO images using AutoClass have been found to improve modeling of TSI, application of AutoClass to the more complex HMI images should enhance understanding of the physical processes at work in solar surface features and their implications for the solar-terrestrial environment. Ulrich, R.K., Parker, D, Bertello, L. and

  1. Global temperature distributions from OGO-6 6300 A airglow measurements

    NASA Technical Reports Server (NTRS)

    Blamont, J. E.; Luton, J. M.; Nisbet, J. S.

    1974-01-01

    The OGO-6 6300 A airglow temperature measurements have been used to develop models of the global temperature distributions under solstice and equinox conditions for the altitude region from 240 to 300 km and for times ranging from dawn in this altitude region to shortly after sunset. The distributions are compared with models derived from satellite orbital decay and incoherent scatter sounding. The seasonal variation of the temperature as a function of latitude is shown to be very different from that derived from static diffusion models with constant boundary conditions.

  2. Far ultraviolet Observations of Jovian low latitude regions with HST/STIS

    NASA Astrophysics Data System (ADS)

    Gustin, J.; Grodent, D.; Gerard, J. C.; Dols, V.; Gladstone, G. R.; Waite, J. H.; Trafton, L. T.

    1999-09-01

    Far ultraviolet observations of the Jovian disk were made at low and mid-latitudes with FUV MAMA/STIS on board HST in January 1999 both in the imaging and spectroscopic modes. An image was obtained with the Lyalpha filter in the hydrogen bulge region for comparison with the expected Lyman-alpha brightness distribution for Ly-alpha resonance scattering. Other images in the 1200-1700 { Angstroms} region show band structures parallel to the equator with fading contrast toward the center and the limb. Spectroscopic observations were made in the 1200-1700 { Angstroms} (G140L) and 1245-1298 { Angstroms} (G140M) regions at ~ 5 { Angstroms} resolution to map the H_2 airglow and the UV absorbents along the STIS slit. Preliminary results indicate that a C_2H_2 absorption signature is clearly observed in the solar ultraviolet reflected spectrum. The ethylene absorption may be mapped to derive variations of the acetylene abundance. The H_2 FUV airglow shows both the fluorescence and the electron impact components. Its spatial variation is described and compared with the expected airglow distribution. We acknowledge funding by NASA and by the PRODEX program of the European space agency.

  3. Satellite uv image processing. Scientific report No. 4, 1 July-10 September 1987

    SciTech Connect

    Rosenberg, N.

    1987-10-09

    The overall objective of the computer program is the photometric and geometric processing of UV satellite images. The data source is the AIRS scanning UV spectrometer aboard the POLAR BEAR satellite. The processing is designed to provide geographic-mapped images that describe the spatial and temporal variability of airglow and aurora of emitting species. The AIRS data stream provided simultaneous records from 3 detectors received at several ground stations from several passes per day. These total about 1500 useful images from launch to Feb. 1987. The major progress during the report period was development of programs to accomplish the following: 1) Statistical filtering of low-count images to provide meaningful brightness estimates; 2) Use of observed limb locations to provide attitude correction in daylit images and attitude estimation in night images to provide accurate ground positions; 3) Normalization of airglow based on column path length and solar flux which allows separation of aurora from airglow portions of the images; 4) Multi-band presentation of auroral features that clearly define differences between the location of emitting species.

  4. Laboratory Investigation of the Airglow Bands

    NASA Astrophysics Data System (ADS)

    Drouin, Brian; Yu, Shanshan; Crawford, Timothy J.; Miller, Charles E.; Yee, Jeng-Hwa

    2013-06-01

    We report the first high spectral resolution laboratory measurements of oxygen A-band night glow simulated using a static discharge cell. Our static discharge system reproduces the conditions of the mesospheric oxygen night glow - suggesting O(^1D) + O_2 as the primary source of the emission. Additionally, use of the static cell has enabled us to collect spectra for rare molecular oxygen isotopologues using isotopically enriched samples. The (0,0), (0,1), and (1,1) b-Xvibrational bands were observed with a Bruker 125 HR for all six isotopologues. The (1,2) and (2,2) bands were observed also for the main isotopologue. The frequencies of the observed (0,1) transitions resolved discrepancies in Raman data for (16-17, 17-17, and 17-18), enabling us to improve the vibrational parameterization of the ground electronic state in the global fit of Yu et al. Rotationally resolved intensities were determined for the (0,0), (0,1) and (1,1) bands. The experimental band intensity ratios I(0,0)/I(0,1) = 13.6 and I(0,0)/I(1,1) = 60 are in excellent agreement with the recent mesospheric remote sensing data. S. Yu, C.E. Miller, B.J. Drouin, H.S.P. Müller, J. Chem. Phys. 136, 024304, 2012

  5. Earth Observation Services (Image Processing Software)

    NASA Technical Reports Server (NTRS)

    1992-01-01

    San Diego State University and Environmental Systems Research Institute, with other agencies, have applied satellite imaging and image processing techniques to geographic information systems (GIS) updating. The resulting images display land use and are used by a regional planning agency for applications like mapping vegetation distribution and preserving wildlife habitats. The EOCAP program provides government co-funding to encourage private investment in, and to broaden the use of NASA-developed technology for analyzing information about Earth and ocean resources.

  6. Night airglows in Venus atmosphere and dynamics around 100 km from VIRTIS-M VEX data. Comparison with the Earth atmosphere.

    NASA Astrophysics Data System (ADS)

    Zasova, L.; Khatuntsev, I.; Shakun, A.; Piccioni, G.; Drossart, P.

    2012-04-01

    Analysis of the O2 1.27um night airglow in the Venus atmosphere is presented. Night glow is extremely variable in space and local time. However, averaged over all nadir observations for Southern hemisphere and over all nadir observations for Northern hemisphere it allows to study a global circulation around 100 km altitude. The global circulation at these levels may be presented by SS-AS, zonal retrograde, as well tides and waves may influence nightglow distribution. In Southern hemisphere in the latitude range 20-60S a maximum emission is found at 22 - 23 h local time, which correlates with minimum horizontal wind speed (downward flow) and minimum emission is observed at 2-4 h, which correlates with maximum of horizontal wind speed. In Northern hemisphere maximum emission is observed at 1 h in latitude range from equator to 40-50°N. It indicates to existence of superposition of SS-AS and zonal retrograde circulation (in the case of SS-AS maximum emission should be found at midnight). For Northern hemisphere there is no simultaneous wind measurements. Thin O3 layer (Montmessin et al. 2011) from SPICAV data was found in Southern hemisphere for latitudes and local time where high O2 airglow (and consequently OH) intensity was also found by VIRTIS. The O2 night airglow of Venus and Earth are compared.

  7. Measured branching ratios for O II2D and 2P transitions in the wavelength range 530 to 800 A. [airglow spectroscopy

    NASA Technical Reports Server (NTRS)

    Morrison, D.; Cunningham, A. J.; Christensen, A. B.

    1981-01-01

    Branching ratios for four sets of extreme ultraviolet transitions terminating on the 2D0 and 2P0 metastable levels of ionized oxygen have been measured. The emissions were excited in both an open window hollow cathode and a capillary discharge lamp, and the branching ratios were derived from the observed intensity ratios of the multiplet pairs. The results are in good agreement with theoretical values and compare favorably, within experimental uncertainties, with line ratios obtained by EUV spectroscopy of the airglow.

  8. Calibration of the Berkeley EUV Airglow Rocket Spectrometer

    NASA Technical Reports Server (NTRS)

    Cotton, Daniel M.; Chakrabarti, Supriya; Siegmund, Oswald

    1989-01-01

    The Berkeley Extreme-ultraviolet Airglow Rocket Spectrometer (BEARS), a multiinstrument sounding rocket payload, made comprehensive measurements of the earth's dayglow. The primary instruments consisted of two near-normal Rowland mount spectrometers: one channel to measure several atomic oxygen features at high spectral resolution (about 1.5 A) in the band passes 980-1040 and 1300-1360 A, and the other to measure EUV dayglow and the solar EUV simultaneously in a much broader bandpass (250-1150 A) at moderate resolution (about 10 A). The payload also included a hydrogen Lyman-alpha photometer to monitor the solar irradiance and goecoronal emissions. The instrument was calibrated at the EUV calibration facility at the University of California at Berkeley, and was subsequently launched successfully on September 30, 1988 aboard a four-stage experimental sounding rocket, Black Brant XII flight 12.041 WT. The calibration procedure and resulting data are presented.

  9. Multi-Instrument Observations of an MSTID over Arecibo Observatory

    NASA Technical Reports Server (NTRS)

    Klenzing, J. H.; Seker, I.; Pfaff, R. F.; Rowland, D. E.; Fung, S. F.; Mathews, J. D.

    2011-01-01

    The Penn State All-Sky Imager (PSASI) at Arecibo Observatory provides planar horizontal context to the vertical ionospheric profiles obtained by the Incoherent Seatter Radar (TSR). Electric field measurements from the Communication/Navigation Outage Forecast System (C/NOFS) satellite are mapped down geomagnetic field lines to the height of the airglow layer; allowing multi-instrument studies of field-aligned irregularities with radar, imager, and satellite. A Medium-Scale Traveling Ionospheric Disturbance (MSTID) was observed during such a conjunction near the December solstice of 2009.

  10. The BAA Observers' Workshops: Imaging comets

    NASA Astrophysics Data System (ADS)

    Mobberley, M. P.

    2003-10-01

    Imaging comets, especially from the UK, used to be nothing less than a battle against the insensitivity of photographic film and the inevitable arrival of cloud on those crucial moon-free nights when a bright comet was close to perihelion. In recent years the situation has changed considerably. On the positive side modern CCDs are twenty times more light-sensitive than the best photographic emulsions, and image processing is far easier than messing around for hours with revolting chemicals in a darkroom. On the negative side the modern lives of working people leave little room for learning new skills and the stress of the modern working day leaves little enthusiasm for a night-time battle with clouds and unfriendly equipment. This author firmly believes that well-thought-out observatories and patient perseverance are the key to achieving success where imaging comets is concerned. Basically, anyone who has learned to use a computer can learn to take good comet images; it is all a question of surmounting the various hurdles in a systematic fashion.

  11. Experimental imaging DOAS observations over Bremen

    NASA Astrophysics Data System (ADS)

    Peters, Enno; Ostendorf, Mareike; Meier, Andreas C.; Schönhardt, Anja; Wittrock, Folkard; Richter, Andreas; Burrows, John P.

    2015-04-01

    Ground-based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) instruments are widely used for the detection of atmospheric trace gases. While current MAX-DOAS instruments are often capable to point in any direction (2D scanner) only one viewing direction can be applied at a time and therefore full hemispheric (i.e. vertical as well as horizontal) scans are not possible as they are much too time-consuming. In this work, measurements of an experimental imaging DOAS instrument are presented. The use of an imaging spectrometer together with a special entrance optic and fibre bundle (separating the entrance optic from the spectrometer) allows simultaneous measurements of 35 vertical viewing directions. In addition, the entrance optic was mounted on a pan-tilt-head that moved the whole optics in azimuthal direction. As a result, whole hemispheric scans were achieved in 0° to 45° elevation and 0° to 360° azimuth (in 10° steps). A full scan was achieved every 6 minutes which is much shorter than lifetimes of anthropogenic pollutants like NO2, therefore providing snapshots of atmospheric pollution scenarios. The experimental imaging DOAS instrument was installed on the rooftop of the IUP building at University of Bremen, Germany, for two complete days from sunrise to sunset in summer 2014. The temporal evolution of NO2 over Bremen during these days is presented as well as the identification of sources. The results of the imaging instrument are compared to those from a (routinely operated) MAX-DOAS instrument close by. Furthermore, slant columns of O4 are presented and compared to simulated O4 slant columns using the radiative transfer model SCIATRAN.

  12. Imaging radar polarization signatures - Theory and observation

    NASA Technical Reports Server (NTRS)

    Van Zyl, Jakob J.; Zebker, Howard A.; Elachi, Charles

    1987-01-01

    Radar polarimetry theory is reviewed, and comparison between theory and experimental results obtained with an imaging radar polarimeter employing two orthogonally polarized antennas is made. Knowledge of the scattering matrix permits calculation of the scattering cross section of a scatterer for any transmit and receive polarization combination, and a new way of displaying the resulting scattering cross section as a function of polarization is introduced. Examples of polarization signatures are presented for several theoretical models of surface scattering, and these signatures are compared with experimentally measured polarization signatures. The coefficient of variation, derived from the polarization signature, may provide information regarding the amount of variation in scattering properties for a given area.

  13. Spatial and Temporal Stability of Airglow Measured in the Meinel Band Window at 1191.3 nm

    NASA Astrophysics Data System (ADS)

    Nguyen, Hien T.; Zemcov, Michael; Battle, John; Bock, James J.; Hristov, Viktor; Korngut, Phillip; Meek, Andrew

    2016-09-01

    We report on the temporal and spatial fluctuations in the atmospheric brightness in the narrow band between Meinel emission lines at 1191.3 nm using a λ/Δλ = 320 near-infrared instrument. We present the instrument design and implementation, followed by a detailed analysis of data taken over the course of a night from Table Mountain Observatory. At low airmasses, the absolute sky brightness at this wavelength is found to be 5330 ± 30 nW m‑2 sr‑1, consistent with previous measurements of the inter-band airglow at these wavelengths. This amplitude is larger than simple models of the continuum component of the airglow emission at these wavelengths, confirming that an extra emissive or scattering component is required to explain the observations. We perform a detailed investigation of the noise properties of the data and find no evidence for a noise component associated with temporal instability in the inter-line continuum. This result demonstrates that in several hours of ∼100 s integrations the noise performance of the instrument does not appear to significantly degrade from expectations, giving a proof of concept that near-infrared line intensity mapping may be feasible from ground-based sites.

  14. An Amateur's Guide to Observing and Imaging the Heavens

    NASA Astrophysics Data System (ADS)

    Morison, Ian

    2014-06-01

    Foreword; Acknowledgments; Prologue: a tale of two scopes; 1. Telescope and observing fundamentals; 2. Refractors; 3. Binoculars and spotting scopes; 4. The Newtonian telescope and its derivatives; 5. The Cassegrain telescope and its derivatives - Schmidt-Cassegrains and Maksutovs; 6. Telescope maintenance, collimation and star testing; 7. Telescope accessories: finders, eyepieces and bino-viewers; 8. Telescope mounts: alt/az and equatorial with their computerised variants; 9. The art of visual observing; 10. Visual observations of the Moon and planets; 11. Imaging the Moon and planets with DSLRs and web-cams; 12. Observing and imaging the Sun in white light and H-alpha; 13. Observing with an astro-video camera to 'see' faint objects; 14. Deep sky imaging with standard and H-alpha modified DSLR cameras; 15. Deep sky imaging with cooled CCD cameras; 16. Auto-guiding techniques and equipment; 17. Spectral studies of the Sun, stars and galaxies; 18. Improving and enhancing images in Photoshop; Index.

  15. The O2 night airglow in Venus atmosphere from VIRTIS VEX measurements: local time and temporal variation

    NASA Astrophysics Data System (ADS)

    Zasova, Ludmila; Drossart, Pierre; Piccioni, Giuseppe; Migliorini, Alessandra; Shakun, Alexey; Altieri, Francesca; Gorinov, Dmitry

    Observation of the O2 1.27 µm airglow intensity distribution on the night side of Venus is one of the methods of study of the circulation in upper mesosphere 90-100 km. VIRTIS-M on board Venus Express made these observations in nadir and limb modes in Southern and Northern hemispheres respectively. To avoid high noisy data we use for analysis only those, obtained with exposure > 3 s. It was found that intensity of emission decreases to poles and to terminators in both hemispheres which gives evidence for existence of SS-AS circulation with transport of the air masses through poles and terminators with ascending/descending flows at SS/AS areas. Asymmetry of distribution of intensity of airglow is observed in both hemispheres. Global map for southern hemisphere (from nadir data) has good statistics at φ > 10-20°S and pretty poor at lower latitudes. Maximum emission was found shifted from midnight by 1 - 2 hours to the evening (22-23h) and deep minimum of emission is found at LT=2-4 h at φ > 20°S. This asymmetry is extended up to equatorial region, however statistic is poor there. No evident indication for existence of the Retrograde Zonal Superrotation (RZS) is found: maximum emission in this case, which is resulting from downwards flow, should be shifted to the morning. VIRTIS limb observations cover the low northern latitudes and they are more sparse at higher latitudes. Intensity of airglow at φ = 0 - 20° N shows wide maximum, which is shifted by 1- 2 h from midnight to morning terminator. This obviously indicates that observed O2 night glow distribution in low North latitudes is explained by a superposition of SS-AS flow and RZS circulation at 95-100 km. This behavior is similar to the NO intensity distribution, obtained by SPICAV. Temporal wariation was found at low latitudes of the Northern hemisphere: during 820 days observations three maxima were observed separated by 150 - 200 days approximately.

  16. Sprite Imaging Results from the ROCSAT2 ISUAL Instrument

    NASA Astrophysics Data System (ADS)

    Mende, S.; Frey, H.; Hsu, R.; Su, H.; Chen, A.; Lee, L.; Fukunishi, H.; Takahashi, Y.

    2004-12-01

    For the systematic observations of Transient Luminous Events (TLE-s, sprites, elve-s, blue jets etc.) and the study of their global distribution, a satellite based camera was launched as part of the "Imager for Sprites and Upper Atmospheric Lightning" (ISUAL) instrument on the Taiwanese ROCSAT 2 satellite. In addition to being a high quality imager of TLE-s the camera is suitable for the observation of aurora and airglow. The imager is bore-sighted with two photometers and the combined instrument package images the atmospheric phenomena and measures their spectral and rapid temporal properties. The imager has a field of view of 20 degrees horizontal and 5 degrees vertical covering a region that is approximately 1000 x 250 km at the earth limb. The view direction is perpendicular to the orbital plane. The imager carries a filter wheel and it can be operated in a number of wavelength regions uninhibited by atmospheric absorption. The spectral ranges are: 427.8 nm for the detection of energetic electron induced phenomena in TLE-s (e.g. blue jets) and aurora, 557.7 nm for the observation of aurora and airglow, 630 nm for the observation of ionospheric irregularities and aurora, wide red/IR N2 1st positive band region for the quantitative observation of sprites and elve-s and 762 nm for the observation of the airglow and especially gravity wave modulated intensity fluctuations. This filter is also effective in suppressing the low altitude part of TLE-s because of the atmospheric O2 absorption. Numerous examples of elve-s were observed both in the N2 1st positive and the 762 nm filter bands. The nicest data on fully developed sprites was obtained in the N2 1st positive band. High intensity gravity waves were seen in the 762 nm band. Examples of various kinds of TLE-s, aurora and airglow that were observed by the imager illustrate its wide variety of application in aeronomy research.

  17. OI 630.0 nm all-sky image observations of medium-scale traveling ionospheric disturbances at geomagnetic conjugate points

    NASA Astrophysics Data System (ADS)

    Stefanello, M. B.; Muella, M. T. A. H.; Amorim, D. C. M.; Machado, C. S.; Bageston, J. V.; Pimenta, A. A.; Martinis, C.; Sullivan, C.; Bittencourt, J. A.; Schuch, N. J.

    2015-06-01

    This paper presents a medium-scale traveling ionospheric disturbance (MSTID) occurrence detected through the OI 630.0 nm emission all-sky images, obtained by ground-based imaging systems installed at close geomagnetic conjugate locations: one at the Southern Space Observatory-SSO/CRS/INPE-MCTI, (29.4°S, 53.8°W), in Sao Martinho da Serra, RS, Brazil, and another at the Arecibo Observatory (18.3°N, 66.7°W), in Puerto Rico. The images obtained show the optical signature of MSTIDs (low intensity regions of 630.0 nm airglow emission), propagating simultaneously in both hemispheres, during geomagnetically quiet conditions (Kp<3). Observations using digital ionosonde installed at Falkland Islands (51.4°S, 57.5°W) and Ramey, Puerto Rico (18.5°N, 67.1°W) show an abrupt upward motion of the ionospheric F region plasma and the occurrence of frequency-type spread-F that could be related to the MSTIDs observed optically. Using Global Positioning System (GPS) receiver data, we also obtained the rate of the Total Electronic Content (TEC) change (ROT) for two geomagnetically conjugated sites-Santa Maria (29.7°S, 53.7°W) and Virgin Islands (17.7° N, 64.7°W). The analysis of TEC allows us to identify an irregular ionization in the F layer associated with the passage of an MSTID. The possible effects of the South America Magnetic Anomaly (SAMA) on the electrodynamic processes that control the inter-hemispheric coupling that give origin to the conjugate MSTIDs are highlighted and discussed.

  18. New developments in observer performance methodology in medical imaging.

    PubMed

    Chakraborty, Dev P

    2011-11-01

    A common task in medical imaging is assessing whether a new imaging system, or a variant of an existing one, is an improvement over an existing imaging technology. Imaging systems are generally quite complex, consisting of several components-for example, image acquisition hardware, image processing and display hardware and software, and image interpretation by radiologists- each of which can affect performance. Although it may appear odd to include the radiologist as a "component" of the imaging chain, because the radiologist's decision determines subsequent patient care, the effect of the human interpretation has to be included. Physical measurements such as modulation transfer function, signal-to-noise ratio, are useful for characterizing the nonhuman parts of the imaging chain under idealized and often unrealistic conditions, such as uniform background phantoms and target objects with sharp edges. Measuring the performance of the entire imaging chain, including the radiologist, and using real clinical images requires different methods that fall under the rubric of observer performance methods or "ROC" analysis, that involve collecting rating data on images. The purpose of this work is to review recent developments in this field, particularly with respect to the free-response method, where location information is also collected. PMID:21978444

  19. Simulations of airglow variations induced by the CO2 increase and solar cycle variation from 1980 to 1991

    NASA Astrophysics Data System (ADS)

    Huang, Tai-Yin

    2016-09-01

    Airglow intensity and Volume Emission Rate (VER) variations induced by the increase of CO2 gas concentration and F10.7 variation (used as a proxy for the 11-year solar cycle variation) were investigated for the period from 1980 to 1991, encompassing a full solar cycle. Two airglow models are used to simulate the induced variations of O(1S) greenline, O2(0,1) atmospheric band , and OH(8,3) airglow for this study. The results show that both the airglow intensities and peak VERs correlate positively with the F10.7 solar cycle variation and display a small linear trend due to the increase of CO2 gas concentration. The solar-cycle induced airglow intensity variations show that O(1S) greenline has the largest variation (~26%) followed by the O2(0,1) atmospheric band (~23%) and then OH(8,3) airglow (~8%) over the 11 year timespan. The magnitudes of the induced airglow intensity variations by the increase of CO2 gas concentration are about an order of magnitude smaller than those by the F10.7 solar cycle variation. In general, the F10.7 solar cycle variation and CO2 increase do not seem to systematically alter the VER peak altitude of the airglow emissions, though the OH(8,3) VER peak altitude moves up slightly during the years when the F10.7 value falls under 100 SFU.

  20. Atmospheric Emissions Photometric Imaging (AEPI) experiment

    NASA Technical Reports Server (NTRS)

    Mende, S. B.

    1988-01-01

    Space plasma physics will be studied on the Atmospheric Laboratory for Applications and Science (ATLAS 1) NASA mission during the Atmospheric Emissions Photometric Imaging (AEPI) experiment. The basic scientific objective of the AEPI is the investigation of the upper atmosphere-ionosphere and the space shuttle environment. The experiment areas of the AEPI include: (1) the investigation of ionospheric transport processes by observing Mg(+) ions; (2) studies of optical properties of artificially induced electron beams; (3) measurement of electron cross sections for selected atmospheric species; (4) studies of natural airglow; and (5) studies of natural auroras. On ATLAS 1, optical emissions generated by the shuttle (shuttle ram glow) will also be investigated.

  1. Laboratory studies on the excitation and collisional deactivation of metastable atoms and molecules in the aurora and airglow

    NASA Technical Reports Server (NTRS)

    Zipf, E. C.

    1974-01-01

    The aeronomy group at the University of Pittsburgh is actively engaged in a series of coordinated satellite, sounding rocket, and laboratory studies designed to expand and clarify knowledge of the physics and chemistry of planetary atmospheres. Three major discoveries have been made that will lead ultimately to a complete and dramatic revision of our ideas on the ionospheres of Mars, Venus, and the Earth and on the origin of their vacuum ultraviolet airglows. The results have already suggested a new generation of ionosphere studies which probably can be carried out best by laser heterodyning techniques. Laboratory studies have also identified, for the first time, the physical mechanism responsible for the remarkable nitric oxide buildup observed in some auroral arcs. This development is an important break-through in auroral physics, and has military ramifications of considerable interest to the Department of Defense. This work may also shed some light on related NO and atomic nitrogen problems in the mesosphere.

  2. Digital image correlation of bone sequential microscopic observations.

    PubMed

    Budyn, Elisa; Jonvaux, Julien; Hoc, Thierry

    2012-08-01

    A method of image correlation is presented to study sequential microscopic observations of human Haversian cortical bone. Imaging biological tissues is sometimes challenging owing to their complex microstructures in particular when microcracks appear. Bone microfractures can be studied in micro compression tests where the progressive growth of small cracks is imaged by light microscopy. The two-dimensional displacement field on the sample surface is then tracked by various digital image correlation methods based on cross-correlation formulation. Because of the potential high number of sequential observations, the method calculates the displacements at given growth steps obtained either by direct comparison of the studied step and the undeformed initial state, called 'direct correlation', or by iterative comparisons of successive pairs of observations, called 'gradual correlation'. In the gradual procedure, two cases are studied, referred to as 'invariant gradual correlation' and 'varying gradual correlation', when the correlation domain is transferred till the last observation or reinitialised for each image pairs. As bone is highly heterogeneous, two types of correlation procedures are considered with or without domain partition (WDP or WODP) delimiting material and strong discontinuities. The precision of the methods is specifically evaluated for experimental observations. PMID:25099565

  3. 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.

  4. Solar energy deposition rates in the mesosphere derived from airglow measurements: Implications for the ozone model deficit problem

    NASA Astrophysics Data System (ADS)

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

    2000-07-01

    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-μm 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.

  5. Preliminary observations from the Auroral and Ionospheric Remote Sensing imager

    NASA Astrophysics Data System (ADS)

    Meng, Ching I.; Huffman, Robert E.

    1987-09-01

    The scientific objectives and the instrumentation of the Polar BEAR's Auroral and Ionospheric Remote Sensing (AIRS) experiment are described together with the techniques employed for global imaging and the results of preliminary observations. The AIRS four-color imager covers selected wavelengths in the visible/near UV and vacuum UV (VUV) ranges. The AIRS experiment also has advantages of narrow 3.0-nm VUV bandpath imaging, not possible with the use of interference filters, and of three alternative modes of operation (imaging, spectrometer, or photometer), possible by controlling the scan mirror and the spectrometer gridding motor. Because of the satellite's high altitude (about 1000 km), most of the auroral oval can be imaged.

  6. Assessment of scanning model observers with hybrid SPECT images

    NASA Astrophysics Data System (ADS)

    Gifford, H. C.; Pretorius, P. H.; King, M. A.

    2008-03-01

    The purpose of this work was to test procedures for applying scanning model observers in order to predict human-observer lesion-detection performance with hybrid images. Hybrid images consist of clinical backgrounds with simulated abnormalities. The basis for this investigation was detection and localization of solitary pulmonary nodules (SPN) in SPECT lung images, and our overall goal has been to determine the extent to which detection of SPN could be improved by proper modeling of the acquisition physics during the iterative reconstruction process. Towards this end, we conducted human-observer localization ROC (LROC) studies to optimize the number of iterations and the postfiltering of four rescaled block-iterative (RBI) reconstruction strategies with various combinations of attenuation correction (AC), scatter correction (SC), and system-resolution correction (RC). This observer data was then used to evaluate a scanning channelized nonprewhitening model observer. A standard "background-known-exactly" (BKE) task formulation overstated the prior knowledge and training that human observers had about the hybrid images. Results from a quasi-BKE task that preserved some degree of structural noise in the detection task demonstrated better agreement with the humans.

  7. Application of MCM image construction to IRAS comet observations

    NASA Technical Reports Server (NTRS)

    Schlapfer, Martin F.; Walker, Russell G.

    1994-01-01

    There is a wealth of IRAS comet data, obtained in both the survey and pointed observations modes. However, these measurements have remained largely untouched due to difficulties in removing instrumental effects from the data. We have developed a version of the Maximum Correlation Method for Image Construction algorithm (MCM) which operates in the moving coordinate system of the comet and properly treats both real cometary motion and apparent motion due to spacecraft parallax. This algorithm has been implemented on a 486/33 PC in FORTRAN and IDL codes. Preprocessing of the IRAS CRDD includes baseline removal, deglitching, and removal of long tails due to dielectric time constants of the detectors. The resulting images are virtually free from instrumental effects and have the highest possible spatial resolution consistent with the data sampling. We present examples of high resolution IRAS images constructed from survey observations of Comets P/Tempel 1 and P/Tempel 2, and pointed observations of IRAS-Araki-Alcock.

  8. Visual perception studies and observer models in medical imaging.

    PubMed

    Burgess, Arthur E

    2011-11-01

    Most academic radiologists will be familiar with receiver operating characteristic (ROC) studies. Fundamental studies of human observer performance are now usually performed by forced-choice methods. Both methods are based on signal detection theory. The ROC method gives an operating curve of true-positive versus false-positive probabilities. The area under the curve, A(Z), can be used a summary performance measure. In the forced-choice method, observers are given 2 or more images with one containing the signal. The observer's task is to select the option most likely to contain the signal. The percentage of correct responses, PC, is a summary performance measure. Precise comparison of the 2 methods is limited to very controlled experiments in which signals (simulated lesions for example) are carefully designed and detection or discrimination is limited by true random noise. Under these conditions, theory predicts a simple relationship between summary measures and human results are consistent with theory. There will be a description of forced-choice experimental methods and data analysis. There has also been considerable work on development of theoretic observer models. Human experiment results have used to evaluate the models. Models that correlate well with human performance in turn can be used for preliminary design of new imaging systems and for selection of image quality metrics for comparing equipment performance, this article will provide a summary of work during the last 30 years on evaluating human signal detection capabilities, observer models and image quality metrics. PMID:21978445

  9. Geomagnetically conjugate observation of plasma bubbles and thermospheric neutral winds at low latitudes

    NASA Astrophysics Data System (ADS)

    Fukushima, D.; Shiokawa, K.; Otsuka, Y.; Nishioka, M.; Kubota, M.; Tsugawa, T.; Nagatsuma, T.; Komonjinda, S.; Yatini, C. Y.

    2015-03-01

    This is the first paper that reports simultaneous observations of zonal drift of plasma bubbles and the thermospheric neutral winds at geomagnetically conjugate points in both hemispheres. The plasma bubbles were observed in the 630 nm nighttime airglow images taken by using highly sensitive all-sky airglow imagers at Kototabang, Indonesia (geomagnetic latitude (MLAT): 10.0°S), and Chiang Mai, Thailand (MLAT: 8.9°N), which are nearly geomagnetically conjugate stations, for 7 h from 13 to 20 UT (from 20 to 03 LT) on 5 April 2011. The bubbles continuously propagated eastward with velocities of 100-125 m/s. The 630 nm images at Chiang Mai and those mapped to the conjugate point of Kototabang fit very well, which indicates that the observed plasma bubbles were geomagnetically connected. The eastward thermospheric neutral winds measured by two Fabry-Perot interferometers were 70-130 m/s at Kototabang and 50-90 m/s at Chiang Mai. We compared the observed plasma bubble drift velocity with the velocity calculated from the observed neutral winds and the model conductivity, to investigate the F region dynamo contribution to the bubble drift velocity. The estimated drift velocities were 60-90% of the observed velocities of the plasma bubbles, suggesting that most of the plasma bubble velocity can be explained by the F region dynamo effect.

  10. Ionospheric zonal velocities at conjugate points over Brazil during the COPEX campaign: Experimental observations and theoretical validations

    NASA Astrophysics Data System (ADS)

    Sobral, J. H. A.; Abdu, M. A.; Pedersen, T. R.; Castilho, Vivian M.; Arruda, Daniela C. S.; Muella, M. T. A. H.; Batista, I. S.; Mascarenhas, M.; de Paula, E. R.; Kintner, P. M.; Kherani, E. A.; Medeiros, A. F.; Buriti, R. A.; Takahashi, H.; Schuch, N. J.; Denardini, C. M.; Zamlutti, C. J.; Pimenta, A. A.; de Souza, J. R.; Bertoni, F. C. P.

    2009-04-01

    We analyze in detail the zonal velocities of large-scale ionospheric plasma depletions over two conjugate stations inferred from OI 630 nm airglow all-sky images obtained during the Conjugate Point Equatorial Experiment (COPEX) campaign carried out in Brazil between October and November 2002. The conjugate stations were Boa Vista (BV) (geogr. 2.8N, 60.7W, dip angle 22.0°N) and Campo Grande (CG) (geogr. 20.5S, 54.7W, dip angle 22.32°S). Over Campo Grande, the zonal velocities were measured also by a system of spaced GPS scintillation receivers. The airglow zonal velocities at the conjugate sites were seen to agree very closely, except for a slightly increased velocity over CG which we attribute to the presence of the geomagnetic anomaly. The results show a high degree of alignment of the bubbles along the geomagnetic field lines during the bubble development phase and as the bubbles travel eastward, thereby suggesting that the neutral zonal wind effect in the zonal plasma motion is an integrated effect along the flux tube. The zonal velocities obtained from the GPS technique were always larger than those calculated by the airglow technique, which permitted observation of zonal plasma velocity shear between the altitudes of the airglow emitting layer and of the GPS scintillation. Theoretical ambient plasma zonal velocities calculated using the formulations by Haerendel et al. (1992) and Eccles (1998) are compared with the experimental results. Our results also reveal some degree of dependence of the zonal velocities on the solar flux (F10.7) and magnetic (Kp) indices during the COPEX period.

  11. Stellar Source Selections for Image Validation of Earth Observation Satellite

    NASA Astrophysics Data System (ADS)

    Yu, Jiwoong; Park, Sang-Young; Lim, Dongwook; Lee, Dong-Han; Sohn, Young-Jong

    2011-12-01

    A method of stellar source selection for validating the quality of image is investigated for a low Earth orbit optical remote sensing satellite. Image performance of the optical payload needs to be validated after its launch into orbit. The stellar sources are ideal source points that can be used to validate the quality of optical images. For the image validation, stellar sources should be the brightest as possible in the charge-coupled device dynamic range. The time delayed and integration technique, which is used to observe the ground, is also performed to observe the selected stars. The relations between the incident radiance at aperture and V magnitude of a star are established using Gunn & Stryker's star catalogue of spectrum. Applying this result, an appropriate image performance index is determined, and suitable stars and areas of the sky scene are selected for the optical payload on a remote sensing satellite to observe. The result of this research can be utilized to validate the quality of optical payload of a satellite in orbit.

  12. Solar and airglow measurements aboard the two suborbital flights NASA 36.098 and 36.107

    NASA Technical Reports Server (NTRS)

    Woods, Thomas N.

    1994-01-01

    This suborbital program, involving the University of Colorado (CU), National Center for Atmospheric Research (NCAR), University of California at Berkeley (UCB), and Boston University (BU), has resulted in two rocket flights from the White Sands Missile Range, one in 1992 and one in 1993 as NASA 36.098 and 36.107 respectively. The rocket payload includes five solar instruments and one airglow instrument from CU/NCAR and one solar instrument and two airglow instruments from UCB/BU. This report discusses results on solar radiation measurements and the study of thermospheric airglow, namely the photoelectron excited emissions from N2 and O, for the CU/NCAR program.

  13. Field observations using an AOTF polarimetric imaging spectrometer

    NASA Technical Reports Server (NTRS)

    Cheng, Li-Jen; Hamilton, Mike; Mahoney, Colin; Reyes, George

    1993-01-01

    This paper reports preliminary results of recent field observations using a prototype acousto-optic tunable filter (AOTF) polarimetric imaging spectrometer. The data illustrate application potentials for geoscience. The operation principle of this instrument is different from that of current airborne multispectral imaging instruments, such as AVIRIS. The AOTF instrument takes two orthogonally polarized images at a desired wavelength at one time, whereas AVIRIS takes a spectrum over a predetermined wavelength range at one pixel at a time and the image is constructed later. AVIRIS does not have any polarization measuring capability. The AOTF instrument could be a complement tool to AVIRIS. Polarization measurement is a desired capability for many applications in remote sensing. It is well know that natural light is often polarized due to various scattering phenomena in the atmosphere. Also, scattered light from canopies is reported to have a polarized component. To characterize objects of interest correctly requires a remote sensing imaging spectrometer capable of measuring object signal and background radiation in both intensity and polarization so that the characteristics of the object can be determined. The AORF instrument has the capability to do so. The AOTF instrument has other unique properties. For example, it can provide spectral images immediately after the observation. The instrument can also allow observations to be tailored in real time to perform the desired experiments and to collect only required data. Consequently, the performance in each mission can be increased with minimal resources. The prototype instrument was completed in the beginning of this year. A number of outdoor field experiments were performed with the objective to evaluate the capability of this new technology for remote sensing applications and to determine issues for further improvements.

  14. Space Telescope Imaging Spectrograph Coronagraphic Observations of β Pictoris

    NASA Astrophysics Data System (ADS)

    Heap, Sara R.; Lindler, Don J.; Lanz, Thierry M.; Cornett, Robert H.; Hubeny, Ivan; Maran, S. P.; Woodgate, Bruce

    2000-08-01

    We present new coronagraphic images of β Pictoris obtained with the Space Telescope Imaging Spectrograph (STIS) in 1997 September. The high-resolution images (0.1") clearly detect the circumstellar disk as close to the star as 0.75", corresponding to a projected radius of 15 AU. The images define the warp in the disk with greater precision and at closer radii to β Pic than do previous observations. They show that the warp can be modeled by the projection of two components: the main disk and a fainter component, which is inclined to the main component by 4°-5° and extends only as far as ~4" from the star. We interpret the main component as arising primarily in the outer disk and the tilted component as defining the inner region of the disk. The observed properties of the warped inner disk are inconsistent with a driving force from stellar radiation. However, warping induced by the gravitational potential of one or more planets is consistent with the data. Using models of planet-warped disks constructed by Larwood & Papaloizou, we derive possible masses of the perturbing object. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  15. Automated detection of meteors in observed image sequence

    NASA Astrophysics Data System (ADS)

    Šimberová, Stanislava; Suk, Tomáš

    2015-12-01

    We propose a new detection technique based on statistical characteristics of images in the video sequence. These characteristics displayed in time enable to catch any bright track during the whole sequence. We applied our method to the image datacubes that are created from camera pictures of the night sky. Meteor flying through the Earth's atmosphere leaves a light trail lasting a few seconds on the sky background. We developed a special technique to recognize this event automatically in the complete observed video sequence. For further analysis leading to the precise recognition of object we suggest to apply Fourier and Hough transformations.

  16. Earth Observing-1 Advanced Land Imager: Radiometric Response Calibration

    NASA Technical Reports Server (NTRS)

    Mendenhall, J. A.; Lencioni, D. E.; Evans, J. B.

    2000-01-01

    The Advanced Land Imager (ALI) is one of three instruments to be flown on the first Earth Observing mission (EO-1) under NASA's New Millennium Program (NMP). ALI contains a number of innovative features, including a wide field of view optical design, compact multispectral focal plane arrays, non-cryogenic HgCdTe detectors for the short wave infrared bands, and silicon carbide optics. This document outlines the techniques adopted during ground calibration of the radiometric response of the Advanced Land Imager. Results from system level measurements of the instrument response, signal-to-noise ratio, saturation radiance, and dynamic range for all detectors of every spectral band are also presented.

  17. Coordinated observations of F region 3 m field-aligned plasma irregularities associated with medium-scale traveling ionospheric disturbances

    NASA Astrophysics Data System (ADS)

    Lin, F. F.; Wang, C. Y.; Su, C. L.; Shiokawa, K.; Saito, S.; Chu, Y. H.

    2016-04-01

    Three meter field-aligned irregularities (3 m FAIs) associated with medium-scale traveling ionospheric disturbances (MSTIDs) that occurred on 5 February 2008 were observed by using the Chung-Li 52 MHz coherent scatter radar. Interferometry measurements show that the plasma structures responsible for the 3 m FAI echoes are in a clumpy shape with a horizontal dimension of about 10-78 km in a height range of 220-300 km. In order to investigate the dynamic behaviors of the plasma irregularities at different scales in the bottomside of F region, the VHF radar echo structures from the 3 m FAIs combined with the 630 nm airglow images provided by the Yonaguni all-sky imager are compared and analyzed. The results show that the radar echoes were located at the west edge of the depletion zones of the 630 nm airglow image of the MSTIDs. The bulk echo structures of the 3 m FAIs drifted eastward at a mean trace velocity of about 30 m/s that is in general agreement with the zonal trace velocity of the MSTIDs shown in the 630 nm airglow images. These results suggest that the observed F region 3 m FAIs for the present case can be regarded as the targets that are frozen in the local region of the MSTIDs. In addition, the radar-observed 3 m FAI echo intensity and spectral width bear high correlations to the percentage variations of the 630 nm emission intensity. These results seem to suggest that through the nonlinear turbulence cascade process, the MSTID-associated 3 m FAIs are very likely generated from the kilometer-scale plasma irregularities with large amplitude excited by the gradient drift instability.

  18. High-speed imaging system for observation of discharge phenomena

    NASA Astrophysics Data System (ADS)

    Tanabe, R.; Kusano, H.; Ito, Y.

    2008-11-01

    A thin metal electrode tip instantly changes its shape into a sphere or a needlelike shape in a single electrical discharge of high current. These changes occur within several hundred microseconds. To observe these high-speed phenomena in a single discharge, an imaging system using a high-speed video camera and a high repetition rate pulse laser was constructed. A nanosecond laser, the wavelength of which was 532 nm, was used as the illuminating source of a newly developed high-speed video camera, HPV-1. The time resolution of our system was determined by the laser pulse width and was about 80 nanoseconds. The system can take one hundred pictures at 16- or 64-microsecond intervals in a single discharge event. A band-pass filter at 532 nm was placed in front of the camera to block the emission of the discharge arc at other wavelengths. Therefore, clear images of the electrode were recorded even during the discharge. If the laser was not used, only images of plasma during discharge and thermal radiation from the electrode after discharge were observed. These results demonstrate that the combination of a high repetition rate and a short pulse laser with a high speed video camera provides a unique and powerful method for high speed imaging.

  19. Difference image analysis of defocused observations with CSTAR

    SciTech Connect

    Oelkers, Ryan J.; Macri, Lucas M.; Wang, Lifan; Ashley, Michael C. B.; Lawrence, Jon S.; Luong-Van, Daniel; Cui, Xiangqun; Gong, Xuefei; Qiang, Liu; Yang, Huigen; Yuan, Xiangyan; Zhou, Xu; Feng, Long-Long; Zhu, Zhenxi; Pennypacker, Carl R.; York, Donald G.

    2015-02-01

    The Chinese Small Telescope ARray carried out high-cadence time-series observations of 27 square degrees centered on the South Celestial Pole during the Antarctic winter seasons of 2008–2010. Aperture photometry of the 2008 and 2010 i-band images resulted in the discovery of over 200 variable stars. Yearly servicing left the array defocused for the 2009 winter season, during which the system also suffered from intermittent frosting and power failures. Despite these technical issues, nearly 800,000 useful images were obtained using g, r, and clear filters. We developed a combination of difference imaging and aperture photometry to compensate for the highly crowded, blended, and defocused frames. We present details of this approach, which may be useful for the analysis of time-series data from other small-aperture telescopes regardless of their image quality. Using this approach, we were able to recover 68 previously known variables and detected variability in 37 additional objects. We also have determined the observing statistics for Dome A during the 2009 winter season; we find the extinction due to clouds to be less than 0.1 and 0.4 mag for 40% and 63% of the dark time, respectively.

  20. Einstein imaging observations of clusters with a bimodal mass distribution

    NASA Technical Reports Server (NTRS)

    Forman, W.; Bechtold, J.; Blair, W.; Giacconi, R.; Van Speybroeck, L.; Jones, C.

    1981-01-01

    Einstein imaging observations of four X-ray clusters of galaxies characterized by a double X-ray surface brightness and thus mass distribution are presented. The clusters A98, A115, A1750 and SC 0627-54 were found to exhibit two enhancements in their X-ray surface brightness distributions in observations made with the Einstein Imaging Proportional Counter. Calculations of the probability that the clusters represent chance superpositions indicate that the double clusters are physically associated. The radial distributions of the components are inconsistent with those of single point sources, and have been used to derive cluster luminosities which are typical of rich clusters. Masses of the subclusters are also found to be typical of bound and virialized clusters with gas contributing 10%. Within the framework of the hierarchical theory of galactic clustering, the double clusters are suggested to represent an intermediate evolutionary stage before the merger of subclusters into a relaxed Coma-type cluster.

  1. Terrestrial Myriametric Radio Burst Observed by IMAGE and Geotail Satellites

    NASA Technical Reports Server (NTRS)

    Fung, Shing F.; Hashimoto, Kozo; Boardsen, Scott A.; Garcia, Leonard N.; Green, James L.; Matsumoto, Hiroshi; Reinisch, Bodo W.

    2010-01-01

    We report IMAGE and Geotail simultaneous observations of a terrestrial myriametric radio burst (TMRB) detected on August 19, 2001. The TMRB was confined in time (0830-1006 UT) and frequency (12-50 kHz), suggesting a fan beam-like emission pattern from a single discrete source. Analysis and comparisons with existing TMR radiations strongly suggest that the TMRB is a distinct emission perhaps resulting from dayside magnetic reconnection instigated by northward interplanetary field condition.

  2. Retinex Image Processing: Improved Fidelity To Direct Visual Observation

    NASA Technical Reports Server (NTRS)

    Jobson, Daniel J.; Rahman, Zia-Ur; Woodell, Glenn A.

    1996-01-01

    Recorded color images differ from direct human viewing by the lack of dynamic range compression and color constancy. Research is summarized which develops the center/surround retinex concept originated by Edwin Land through a single scale design to a multi-scale design with color restoration (MSRCR). The MSRCR synthesizes dynamic range compression, color constancy, and color rendition and, thereby, approaches fidelity to direct observation.

  3. Digital image processing of earth observation sensor data

    NASA Technical Reports Server (NTRS)

    Bernstein, R.

    1976-01-01

    This paper describes digital image processing techniques that were developed to precisely correct Landsat multispectral earth observation data and gives illustrations of the results achieved, e.g., geometric corrections with an error of less than one picture element, a relative error of one-fourth picture element, and no radiometric error effect. Techniques for enhancing the sensor data, digitally mosaicking multiple scenes, and extracting information are also illustrated.

  4. Comparison of Imager for Mars Pathfinder spectra with remote observations

    NASA Astrophysics Data System (ADS)

    Herkenhoff, K. E.; Johnson, J. R.; Lemmon, M.; Smith, P. H.

    2001-11-01

    The range of colors and albedos of materials at the Pathfinder landing site is similar to that observed in Viking Orbiter and HST images of Mars, but precise comparisons are hampered by the effects of atmospheric scattering in these data sets and differences in the effective wavelengths of the images. Such comparisons will allow the spectral units observed at the Pathfinder landing site to be placed into a global geologic context, and the composition, physical properties, and origins of Martian surface units to be inferred. We report our progress toward achieving these objectives by calibrating, modeling, and analyzing IMP multispectral observations of various surface materials and comparing them to the color and albedo units observed by the Viking Orbiter cameras, the WF/PC2 on HST, and the MOC wide-angle cameras on MGS. New digital terrain models (DTMs) have been derived from IMP stereo data, and new multispectral image cubes of IMP panoramas have been assembled using improved ISIS radiometric calibration, geometric registration and mosaicking software. The latest version of the IMP calibration software yields significantly different relative reflectances in some cases, but in general changes are small. We have also calibrated and assembled a mosaic of Insurance Pan images, which were losslessly compressed and taken under different illumination/viewing conditions than Super Pan; these data will be useful in better constraining the photometric and atmospheric models that are critically important to this investigation. Software tools were developed that evaluate and apply the University of Arizona atmospheric radiative transfer model. Scene reflectivity (as seen from orbit, in an arbitrary geometry) was simulated, including both direct and diffuse components to allow shadow brightness to be predicted. Surface normals from the new DTM were used to simulate sky brightness as a function of direction and predict the scene appearance for a given surface reflectivity.

  5. X-ray phase imaging-From static observation to dynamic observation-

    SciTech Connect

    Momose, A.; Yashiro, W.; Olbinado, M. P.; Harasse, S.

    2012-07-31

    We are attempting to expand the technology of X-ray grating phase imaging/tomography to enable dynamic observation. X-ray phase imaging has been performed mainly for static cases, and this challenge is significant since properties of materials (and hopefully their functions) would be understood by observing their dynamics in addition to their structure, which is an inherent advantage of X-ray imaging. Our recent activities in combination with white synchrotron radiation for this purpose are described. Taking advantage of the fact that an X-ray grating interferometer functions with X-rays of a broad energy bandwidth (and therefore high flux), movies of differential phase images and visibility images are obtained with a time resolution of a millisecond. The time resolution of X-ray phase tomography can therefore be a second. This study is performed as a part of a project to explore X-ray grating interferometry, and our other current activities are also briefly outlined.

  6. Observer detection limits for a dedicated SPECT breast imaging system

    NASA Astrophysics Data System (ADS)

    Cutler, S. J.; Perez, K. L.; Barnhart, H. X.; Tornai, M. P.

    2010-04-01

    An observer-based contrast-detail study is performed in an effort to evaluate the limits of object detectability using a dedicated CZT-based breast SPECT imaging system under various imaging conditions. A custom geometric contrast-resolution phantom was developed that can be used for both positive ('hot') and negative contrasts ('cold'). The 3 cm long fillable tubes are arranged in six sectors having equal inner diameters ranging from 1 mm to 6 mm with plastic wall thicknesses of <0.25 mm, on a pitch of twice their inner diameters. Scans of the activity filled tubes using simple circular trajectories are obtained in a 215 mL uniform water filled cylinder, varying the rod:background concentration ratios from 10:1 to 1:10 simulating a large range of biological uptake ratios. The rod phantom is then placed inside a non-uniformly shaped 500 mL breast phantom and scans are again acquired using both simple and complex 3D trajectories for similarly varying contrasts. Summed slice and contiguous multi-slice images are evaluated by five independent readers, identifying the smallest distinguishable rod for each concentration and experimental setup. Linear and quadratic regression is used to compare the resulting contrast-detail curves. Results indicate that in a moderately low-noise 500 mL background, using the SPECT camera having 2.5 mm intrinsic pixels, the mean detectable rod was ~3.4 mm at a 10:1 ratio, degrading to ~5.2 mm with the 2.5:1 concentration ratio. The smallest object detail was observed using a 45° tilted trajectory acquisition. The complex 3D projected sine wave acquisition, however, had the most consistent combined intra- and inter-observer results, making it potentially the best imaging approach for consistent results.

  7. Center determination for trailed sources in astronomical observation images

    NASA Astrophysics Data System (ADS)

    Du, Jun Ju; Hu, Shao Ming; Chen, Xu; Guo, Di Fu

    2014-11-01

    Images with trailed sources can be obtained when observing near-Earth objects, such as small astroids, space debris, major planets and their satellites, no matter the telescopes track on sidereal speed or the speed of target. The low centering accuracy of these trailed sources is one of the most important sources of the astrometric uncertainty, but how to determine the central positions of the trailed sources accurately remains a significant challenge to image processing techniques, especially in the study of faint or fast moving objects. According to the conditions of one-meter telescope at Weihai Observatory of Shandong University, moment and point-spread-function (PSF) fitting were chosen to develop the image processing pipeline for space debris. The principles and the implementations of both two methods are introduced in this paper. And some simulated images containing trailed sources are analyzed with each technique. The results show that two methods are comparable to obtain the accurate central positions of trailed sources when the signal to noise (SNR) is high. But moment tends to fail for the objects with low SNR. Compared with moment, PSF fitting seems to be more robust and versatile. However, PSF fitting is quite time-consuming. Therefore, if there are enough bright stars in the field, or the high astronometric accuracy is not necessary, moment is competent. Otherwise, the combination of moment and PSF fitting is recommended.

  8. Difference Image Analysis of De-Focused 2009 CSTAR Observations

    NASA Astrophysics Data System (ADS)

    Oelkers, Ryan J.; Macri, L. M.; Wang, L.; PLATO; CSTAR

    2014-01-01

    The Chinese Small Telescope ARray (CSTAR) carried out high-cadence time-series observations of a 27-square degree region centered on the South Celestial Pole during the Antarctic winter seasons of 2008, 2009 and 2010. Analysis of the 2008 and 2010 data using aperture photometry resulted in the discovery of 198 variables with i < 15.3 mag. Routine servicing completed after the 2008 winter season left the telescope out of focus for the 2009 winter season. The telescope also suffered a power loss after ~2 months of observation. In spite of the telescope's technical issues, nearly 250,000 usable images were taken in the 'g', 'N', and 'r' bands. We used a combination of difference imaging and aperture photometry to compensate for the highly crowded, blended and out of focus images. We are able to recover more than 100 of the variables in the 'g'-band and have discovered about 20 objects to be explored further. We discuss the analysis of all of these objects in the 'N' and 'r' bands as well. We also present the preliminary results of the application of this technique to another time-series data set taken from Tolar Grande, Argentina during the 2013 southern winter. Ryan J. Oelkers would like to acknowledge the support of a grant from the George P. and Cynthia Woods Mitchell Institute for Fundamental Physics & Astronomy.

  9. Coordinated thermospheric day-night airglow and ionospheric measurements from low latitudes—First results

    NASA Astrophysics Data System (ADS)

    Taori, Alok; Sridharan, R.; Chakrabarty, D.; Narayanan, R.; Ramarao, P. V. S.

    2001-04-01

    The Dayglow photometer which monitors the O(¹D) 630.0 nm thermospheric airglow emission, has been converted into a day-night photometer and was operated from Waltair (17.7°N, 83.3°E dip. Lat. 10.09°N) during March 1998 as a part of the Indian Solar Terrestrial Energy Programme (ISTEP) campaign. The first results on the day-night airglow measurements together with ionosonde data from the same location are scrutinized in the present exercise. The base height of the F-layer (h'F) showed a strong negative correlation with dayglow intensity similar to nighttime conditions and a new empirical relation (Barbier type) linking the F-region electron densities and the h'F with the dayglow intensity has been worked out highlighting the importance of chemical processes in OI 630.0 nm dayglow and its variabilities.

  10. Improved SOT (Hinode mission) high resolution solar imaging observations

    NASA Astrophysics Data System (ADS)

    Goodarzi, H.; Koutchmy, S.; Adjabshirizadeh, A.

    2015-08-01

    We consider the best today available observations of the Sun free of turbulent Earth atmospheric effects, taken with the Solar Optical Telescope (SOT) onboard the Hinode spacecraft. Both the instrumental smearing and the observed stray light are analyzed in order to improve the resolution. The Point Spread Function (PSF) corresponding to the blue continuum Broadband Filter Imager (BFI) near 450 nm is deduced by analyzing (i) the limb of the Sun and (ii) images taken during the transit of the planet Venus in 2012. A combination of Gaussian and Lorentzian functions is selected to construct a PSF in order to remove both smearing due to the instrumental diffraction effects (PSF core) and the large-angle stray light due to the spiders and central obscuration (wings of the PSF) that are responsible for the parasitic stray light. A Max-likelihood deconvolution procedure based on an optimum number of iterations is discussed. It is applied to several solar field images, including the granulation near the limb. The normal non-magnetic granulation is compared to the abnormal granulation which we call magnetic. A new feature appearing for the first time at the extreme- limb of the disk (the last 100 km) is discussed in the context of the definition of the solar edge and of the solar diameter. A single sunspot is considered in order to illustrate how effectively the restoration works on the sunspot core. A set of 125 consecutive deconvolved images is assembled in a 45 min long movie illustrating the complexity of the dynamical behavior inside and around the sunspot.

  11. OBSERVATIONS OF RECONNECTING FLARE LOOPS WITH THE ATMOSPHERIC IMAGING ASSEMBLY

    SciTech Connect

    Warren, Harry P.; Sheeley, Neil R. Jr.; O'Brien, Casey M.

    2011-12-01

    Perhaps the most compelling evidence for the role of magnetic reconnection in solar flares comes from the supra-arcade downflows that have been observed above many post-flare loop arcades. These downflows are thought to be related to highly non-potential field lines that have reconnected and are propagating away from the current sheet. We present new observations of supra-arcade downflows taken with the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO). The morphology and dynamics of the downflows observed with AIA provide new evidence for the role of magnetic reconnection in solar flares. With these new observations we are able to measure downflows originating at larger heights than in previous studies. We find, however, that the initial velocities measured here ({approx}144 km s{sup -1}) are well below the Alfven speed expected in the lower corona, and consistent with previous results. We also find no evidence that the downflows brighten with time, as would be expected from chromospheric evaporation. These observations suggest that simple two-dimensional models cannot explain the detailed observations of solar flares.

  12. Molecular and Ionized Hydrogen in 30 Doradus. I. Imaging Observations

    NASA Astrophysics Data System (ADS)

    Yeh, Sherry C. C.; Seaquist, Ernest R.; Matzner, Christopher D.; Pellegrini, Eric W.

    2015-07-01

    We present the first fully calibrated H2 1-0 S(1) image of the entire 30 Doradus nebula. The observations were conducted using the NOAO Extremely Wide-field Infrared Imager (NEWFIRM) on the CTIO 4 m Blanco Telescope. Together with a NEWFIRM Brγ image of 30 Doradus, our data reveal the morphologies of the warm molecular gas and ionized gas in 30 Doradus. The brightest H2-emitting area, which extends from the northeast to the southwest of R136, is a photodissociation region (PDR) viewed face-on, while many clumps and pillar features located at the outer shells of 30 Doradus are PDRs viewed edge-on. Based on the morphologies of H2, Brγ, CO, and 8 μm emission, the H2 to Brγ line ratio, and Cloudy models, we find that the H2 emission is formed inside the PDRs of 30 Doradus, 2-3 pc to the ionization front of the H ii region, in a relatively low-density environment <104 cm-3. Comparisons with Brγ, 8 μm, and CO emission indicate that H2 emission is due to fluorescence, and provide no evidence for shock excited emission of this line.

  13. A CMOS TDI image sensor for Earth observation

    NASA Astrophysics Data System (ADS)

    Rushton, Joseph E.; Stefanov, Konstantin D.; Holland, Andrew D.; Endicott, James; Mayer, Frederic; Barbier, Frederic

    2015-09-01

    Time Delay and Integration (TDI) is used to increase the Signal to Noise Ratio (SNR) in image sensors when imaging fast moving objects. One important TDI application is in Earth observation from space. In order to operate in the space radiation environment, the effect that radiation damage has on the performance of the image sensors must be understood. This work looks at prototype TDI sensor pixel designs, produced by e2v technologies. The sensor is a CCD-like charge transfer device, allowing in-pixel charge summation, produced on a CMOS process. The use of a CMOS process allows potential advantages such as lower power consumption, smaller pixels, higher line rate and extra on-chip functionality which can simplify system design. CMOS also allows a dedicated output amplifier per column allowing fewer charge transfers and helping to facilitate higher line rates than CCDs. In this work the effect on the pixels of radiation damage from high energy protons, at doses relevant to a low Earth orbit mission, is presented. This includes the resulting changes in Charge Transfer inefficiency (CTI) and dark signal.

  14. First Radio Burst Imaging Observation From Mingantu Ultrawide Spectral Radioheliograph

    NASA Astrophysics Data System (ADS)

    Yan, Yihua; Chen, Linjie; Yu, Sijie; CSRH Team

    2015-08-01

    Radio imaging spectroscopy over wide range wavelength in dm/cm-bands will open new windows on solar flares and coronal mass ejections by tracing the radio emissions from accelerated electrons. The Chinese Spectral Radioheliograph (CSRH) with two arrays in 400MHz-2GHz /2-15GHz ranges with 64/532 frequency channels have been established in Mingantu Observing Station, Inner Mongolia of China, since 2013 and is in test observations now. CSRH is renamed as MUSER (Mingantu Ultrawide SpEctral Radioheliograph) after it's accomplishment We will introduce the progress and current status of CSRH. Some preliminary results of CSRH will be presented.On 11 Nov2014, the first burst event was registered by MUSER-I array at 400MHz-2GHz waveband. According to SGD event list there was a C-class flare peaked at 04:49UT in the disk center and the radio bursts around 04:22-04:24UT was attributed to this flare. However, MUSER-I image observation of the burst indicates that the radio burst peaked around 04:22UT was due to the eruption at the east limb of the Sun and connected to a CME appeared in that direction about 1 hour later. This demonstrate the importance of the spectroscopy observation of the solar radio burst.Acknowledgement: The CSRH team includes Wei Wang, Zhijun Chen, Fei Liu, Lihong Geng and Jian Zhang and CSRH project is supported by National Major Scientific Equipment R&D Project ZDYZ2009-3. The research was also supported by NSFC grants (11433006, 11221063), MOST grant (MOST2011CB811401), CAS Pilot-B Project (XDB09000000) and Marie Curie PIRSES- GA-295272-RADIOSUN.

  15. Bayesian Analysis of Hmi Images and Comparison to Tsi Variations and MWO Image Observables

    NASA Astrophysics Data System (ADS)

    Parker, D. G.; Ulrich, R. K.; Beck, J.; Tran, T. V.

    2015-12-01

    We have previously applied the Bayesian automatic classification system AutoClass to solar magnetogram and intensity images from the 150 Foot Solar Tower at Mount Wilson to identify classes of solar surface features associated with variations in total solar irradiance (TSI) and, using those identifications, modeled TSI time series with improved accuracy (r > 0.96). (Ulrich, et al, 2010) AutoClass identifies classes by a two-step process in which it: (1) finds, without human supervision, a set of class definitions based on specified attributes of a sample of the image data pixels, such as magnetic field and intensity in the case of MWO images, and (2) applies the class definitions thus found to new data sets to identify automatically in them the classes found in the sample set. HMI high resolution images capture four observables-magnetic field, continuum intensity, line depth and line width-in contrast to MWO's two observables-magnetic field and intensity. In this study, we apply AutoClass to the HMI observables for images from June, 2010 to December, 2014 to identify solar surface feature classes. We use contemporaneous TSI measurements to determine whether and how variations in the HMI classes are related to TSI variations and compare the characteristic statistics of the HMI classes to those found from MWO images. We also attempt to derive scale factors between the HMI and MWO magnetic and intensity observables.The ability to categorize automatically surface features in the HMI images holds out the promise of consistent, relatively quick and manageable analysis of the large quantity of data available in these images. Given that the classes found in MWO images using AutoClass have been found to improve modeling of TSI, application of AutoClass to the more complex HMI images should enhance understanding of the physical processes at work in solar surface features and their implications for the solar-terrestrial environment.Ulrich, R.K., Parker, D, Bertello, L. and

  16. The Saturn System as Observed by Cassini's Ultraviolet Imaging Spectrograph

    NASA Technical Reports Server (NTRS)

    Esposito, L. W.; Hansen, C. J.; Colwell, J.; Hendrix, A. R.; McClintock, W. E.; Shemansky, D. E.

    2005-01-01

    The Cassini Ultraviolet Imaging Spectrograph (UVIS) has major new findings in all aspects of Saturn science: Saturn, its rings, Titan and the icy satellites, and the Saturn magnetosphere. Dynamic interactions between neutrals, ions, rings, moons and meteoroids produce a highly structured and time variable Saturn system. Highlights and outstanding new results will be reported, focusing on Saturn s moons and their interaction with their environment. The UVIS is one of Cassini s suite of remote sensing instruments. The UVIS instrument includes channels for extreme UV (55 to 110 nm) and far UV (110 to 190 nm) spectroscopic imaging, high speed photometry of stellar occultations, solar EUV occultation, and a hydrogen/deuterium absorption cell. UVIS has detected products of water dissociation, neutral oxygen and OH, which dominate the Saturn inner magnetosphere, in contrast to Jupiter, and H fills the entire magnetosphere apparently extending through the magnetopause at far greater density than the ion population. The O and OH and a fraction of the H are probably the products of water physical chemistry, and derived ultimately from water ice. Observed fluctuations indicate close interactions with plasma sources. Sputtering from the satellites water ice surfaces is insufficient to supply the observed mass. Stochastic events in the E ring may be the ultimate source.

  17. On the causes of plasmaspheric rotation variability: IMAGE EUV observations

    NASA Astrophysics Data System (ADS)

    Galvan, David A.; Moldwin, Mark B.; Sandel, Bill R.; Crowley, Geoff

    2010-01-01

    IMAGE EUV observations demonstrate that the plasmasphere usually does not corotate as assumed in simple convection models, even at low L shells. We carry out a statistical survey of plasmaspheric rotation rates over several months of IMAGE EUV data in 2001, using two different measurement techniques. We test the prevailing hypothesis, that subcorotation is due to enhanced auroral zone Joule heating driving equatorward thermospheric winds, by testing for correlation of rotation rates with several geomagnetic indices. Azimuthal features such as "notches" are tracked in local time over a single pass of the IMAGE satellite, both visually and using an automated cross-correlation routine. Each technique provides an estimate of the plasmasphere's rotation rate. We find a weak correlation between rotation rate and Dst, Kp, AE, the midnight boundary index (MBI), and Joule heating estimates from assimilative mapping of ionospheric electrodynamics (AMIE) at L = 2.5, but not at L = 3.5. In general, lower rotation rates correspond to higher auroral and geomagnetic activity. We also make the first direct observation of plasmaspheric superrotation. The plasmaspheric rotation rate is found to be highly variable on multiday timescales, but the typical state of the plasmasphere is subcorotation, with inferred mean values ranging from 88% to 95% of corotation, depending on L shell. In addition, a statistical analysis shows that rotation rates near dusk are generally lower than those at dawn, suggesting that local time and magnetospheric convection contribute to the variation in rotation rate as well. We conclude that the cause of variability in plasmaspheric rotation rate is a combination of storm phase, local-time-dependent convection, and westward ionospheric drift.

  18. Image quality in CT: From physical measurements to model observers.

    PubMed

    Verdun, F R; Racine, D; Ott, J G; Tapiovaara, M J; Toroi, P; Bochud, F O; Veldkamp, W J H; Schegerer, A; Bouwman, R W; Giron, I Hernandez; Marshall, N W; Edyvean, S

    2015-12-01

    Evaluation of image quality (IQ) in Computed Tomography (CT) is important to ensure that diagnostic questions are correctly answered, whilst keeping radiation dose to the patient as low as is reasonably possible. The assessment of individual aspects of IQ is already a key component of routine quality control of medical x-ray devices. These values together with standard dose indicators can be used to give rise to 'figures of merit' (FOM) to characterise the dose efficiency of the CT scanners operating in certain modes. The demand for clinically relevant IQ characterisation has naturally increased with the development of CT technology (detectors efficiency, image reconstruction and processing), resulting in the adaptation and evolution of assessment methods. The purpose of this review is to present the spectrum of various methods that have been used to characterise image quality in CT: from objective measurements of physical parameters to clinically task-based approaches (i.e. model observer (MO) approach) including pure human observer approach. When combined together with a dose indicator, a generalised dose efficiency index can be explored in a framework of system and patient dose optimisation. We will focus on the IQ methodologies that are required for dealing with standard reconstruction, but also for iterative reconstruction algorithms. With this concept the previously used FOM will be presented with a proposal to update them in order to make them relevant and up to date with technological progress. The MO that objectively assesses IQ for clinically relevant tasks represents the most promising method in terms of radiologist sensitivity performance and therefore of most relevance in the clinical environment. PMID:26459319

  19. a Three-Dimensional Acoustical Imaging System for Zooplankton Observations

    NASA Astrophysics Data System (ADS)

    McGehee, Duncan Ewell

    This dissertation describes the design, testing, and use of a three-dimensional acoustical imaging system, called Fish TV, or FTV, for tracking zooplankton swimming in situ. There is an increasing recognition that three -dimensional tracks of individual plankters are needed for some studies in behavioral ecology including, for example, the role of individual behavior in patch formation and maintenance. Fish TV was developed in part to provide a means of examining zooplankton swimming behavior in a non-invasive way. The system works by forming a set of 64 acoustic beams in an 8 by 8 pattern, each beam 2 ^circ by 2^circ , for a total coverage of 16^circ by 16^circ. The 8 by 8 beams form two dimensions of the image; range provides the third dimension. The system described in the thesis produces three-dimensional images at the rate of approximately one per second. A set of laboratory and field experiments is described that demonstrates the capabilities of the system. The final field experiment was the in situ observation of zooplankton swimming behavior at a site in the San Diego Trough, 15 nautical miles southwest of San Diego. 314 plankters were tracked for one minute. It was observed that there was no connection between the acoustic size of the animals and their repertoire of swimming behaviors. Other contributions of the dissertation include the development of two novel methods for generating acoustic beams with low side lobes. The first is the method of dense random arrays. The second is the optimum mean square quantized aperture method. Both methods were developed originally as ways to "build a better beam pattern" for Fish TV, but also have general significance with respect to aperture theory.

  20. Processing Earth Observing images with Ames Stereo Pipeline

    NASA Astrophysics Data System (ADS)

    Beyer, R. A.; Moratto, Z. M.; Alexandrov, O.; Fong, T.; Shean, D. E.; Smith, B. E.

    2013-12-01

    ICESat with its GLAS instrument provided valuable elevation measurements of glaciers. The loss of this spacecraft caused a demand for alternative elevation sources. In response to that, we have improved our Ames Stereo Pipeline (ASP) software (version 2.1+) to ingest satellite imagery from Earth satellite sources in addition to its support of planetary missions. This enables the open source community a free method to generate digital elevation models (DEM) from Digital Globe stereo imagery and alternatively other cameras using RPC camera models. Here we present details of the software. ASP is a collection of utilities written in C++ and Python that implement stereogrammetry. It contains utilities to manipulate DEMs, project imagery, create KML image quad-trees, and perform simplistic 3D rendering. However its primary application is the creation of DEMs. This is achieved by matching every pixel between the images of a stereo observation via a hierarchical coarse-to-fine template matching method. Matched pixels between images represent a single feature that is triangulated using each image's camera model. The collection of triangulated features represents a point cloud that is then grid resampled to create a DEM. In order for ASP to match pixels/features between images, it requires a search range defined in pixel units. Total processing time is proportional to the area of the first image being matched multiplied by the area of the search range. An incorrect search range for ASP causes repeated false positive matches at each level of the image pyramid and causes excessive processing times with no valid DEM output. Therefore our system contains automatic methods for deducing what the correct search range should be. In addition, we provide options for reducing the overall search range by applying affine epipolar rectification, homography transform, or by map projecting against a prior existing low resolution DEM. Depending on the size of the images, parallax, and image

  1. Polar cap patches observed during the magnetic storm of November 2003: observations and modeling

    NASA Astrophysics Data System (ADS)

    Valladares, C. E.; Pedersen, T.; Sheehan, R.

    2015-09-01

    We present multi-instrumented measurements and multi-technique analysis of polar cap patches observed early during the recovery phase of the major magnetic storm of 20 November 2003 to investigate the origin of the polar cap patches. During this event, the Qaanaaq imager observed elongated polar cap patches, some of which containing variable brightness; the Qaanaaq digisonde detected abrupt NmF2 fluctuations; the Sondrestrom incoherent scatter radar (ISR) measured patches placed close to but poleward of the auroral oval-polar cap boundary; and the DMSP-F13 satellite intersected topside density enhancements, corroborating the presence of the patches seen by the imager, the digisonde, and the Sondrestrom ISR. A 2-D cross-correlation analysis was applied to series of two consecutive red-line images, indicating that the magnitude and direction of the patch velocities were in good agreement with the SuperDARN convection patterns. We applied a back-tracing analysis to the patch locations and found that most of the patches seen between 20:41 and 21:29 UT were likely transiting the throat region near 19:41 UT. Inspection of the SuperDARN velocities at this time indicates spatial and temporal collocation of a gap region between patches and large (1.7 km s-1) line-of-sight velocities. The variable airglow brightness of the patches observed between 20:33 and 20:43 UT was investigated using the numerical Global Theoretical Ionospheric Model (GTIM) driven by the SuperDARN convection patterns and a variable upward/downward neutral wind. Our numerical results indicate that variations in the airglow intensity up to 265 R can be produced by a constant 70 m s-1 downward vertical wind.

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

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

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

  3. Sea state variability observed by high resolution satellite radar images

    NASA Astrophysics Data System (ADS)

    Pleskachevsky, A.; Lehner, S.

    2012-04-01

    The spatial variability of the wave parameters is measured and investigated using new TerraSAR-X (TS-X) satellite SAR (Synthetic Aperture Radar) images. Wave groupiness, refraction and breaking of individual wave are studied. Space borne SAR is a unique sensor providing two dimensional information of the ocean surface. Due to its daylight, weather independency and global coverage, the TS-X radar is particularly suitable for many ocean and coastal observations and it acquires images of the sea surface with up to 1m resolution; individual ocean waves with wavelength below 30m are detectable. Two-dimensional information of the ocean surface, retrieved using TS-X data, is validated for different oceanographic applications: derivation of the fine resolved wind field (XMOD algorithm) and integrated sea state parameters (XWAVE algorithm). The algorithms are capable to take into account fine-scale effects in the coastal areas. This two-dimensional information can be successfully applied to validate numerical models. For this, wind field and sea state information retrieved from SAR images are given as input for a spectral numerical wave model (wind forcing and boundary condition). The model runs and sensitivity studies are carried out at a fine spatial horizontal resolution of 100m. The model results are compared to buoy time series at one location and with spatially distributed wave parameters obtained from SAR. The comparison shows the sensitivity of waves to local wind variations and the importance of local effects on wave behavior in coastal areas. Examples for the German Bight, North Sea and Rottenest Island, Australia are shown. The wave refraction, rendered by high resolution SAR images, is also studied. The wave ray tracking technique is applied. The wave rays show the propagation of the peak waves in the SAR-scenes and are estimated using image spectral analysis by deriving peak wavelength and direction. The changing of wavelength and direction in the rays allows

  4. Images of Bottomside Irregularities Observed at Topside Altitudes

    NASA Technical Reports Server (NTRS)

    Burke, William J.; Gentile, Louise C.; Shomo, Shannon R.; Roddy, Patrick A.; Pfaff, Robert F.

    2012-01-01

    We analyzed plasma and field measurements acquired by the Communication/ Navigation Outage Forecasting System (C/NOFS) satellite during an eight-hour period on 13-14 January 2010 when strong to moderate 250 MHz scintillation activity was observed at nearby Scintillation Network Decision Aid (SCINDA) ground stations. C/NOFS consistently detected relatively small-scale density and electric field irregularities embedded within large-scale (approx 100 km) structures at topside altitudes. Significant spectral power measured at the Fresnel (approx 1 km) scale size suggests that C/NOFS was magnetically conjugate to bottomside irregularities similar to those directly responsible for the observed scintillations. Simultaneous ion drift and plasma density measurements indicate three distinct types of large-scale irregularities: (1) upward moving depletions, (2) downward moving depletions, and (3) upward moving density enhancements. The first type has the characteristics of equatorial plasma bubbles; the second and third do not. The data suggest that both downward moving depletions and upward moving density enhancements and the embedded small-scale irregularities may be regarded as Alfvenic images of bottomside irregularities. This interpretation is consistent with predictions of previously reported theoretical modeling and with satellite observations of upward-directed Poynting flux in the low-latitude ionosphere.

  5. Instrument for the monochromatic observation of all sky auroral images.

    PubMed

    Mende, S B; Eather, R H; Aamodt, E K

    1977-06-01

    To investigate the dynamics of auroras and faint upper atmospheric emissions, a new type of imaging instrument was developed. The instrument is a wide field of view, narrow-spectral-band imaging system using an intensified S.E.C. TV camera in a time exposure mode. Pictures were taken at very low light levels of a few photons per exposure per resolution element. These pictures are displayed in the form of a pseudocolor presentation in which the color represents spectral ratios of two of the observed auroral spectral emission features. The spectral ratios play an important part in the interpretation of auroral particle dynamics. A digital picture processing facility is also part of the system which enables the digital manppulation of the pictures at standard TV rates. As an example, hydrogen auroras can be displayed having been corrected for nonspectral background by subtracting a picture obtained by a suitable background filter. The instrumentation was calibrated in the laboratory and was used in several field xperiments. Elaborate exposure sequences were developed to extend the dynamic range and to cover the large range of auroral brightnesses in a fairly linear manner. PMID:20168774

  6. A method for determining the drift velocity of plasma depletions in the equatorial ionosphere using far-ultraviolet spacecraft observations: initial results

    NASA Astrophysics Data System (ADS)

    England, S. L.; Immel, T. J.; Park, S. H.; Frey, H. U.; Mende, S. B.

    2007-12-01

    The Far-Ultraviolet Imager (IMAGE-FUV) on-board the NASA IMAGE satellite has been used to observe plasma depletions in the nightside equatorial ionosphere. Observations from periods around spacecraft apogee, during which equatorial regions are visible for several hours, have allowed the velocity of these plasma depletions to be determined. A new method for determining the velocity of these depletions using an image analysis technique, Tracking Of Airglow Depletions (TOAD), has been developed. TOAD allows the objective identification and tracking of depletions. The automation of this process has also allowed for the tracking of a greater number of depletions than previously achieved without requiring any human input, which shows that TOAD is suitable for use with large data sets and for future routine monitoring of the ionosphere from space. Furthermore, this allows the drift velocities of each depletion to be determined as a function of magnetic latitude as well as local time. Previous ground-based airglow observations from a small number of locations have indicated that the drift velocities of depletions may vary rapidly with magnetic latitude. Here we shall present the first results from TOAD of this shear in drift velocities from our global sample of depletion drift velocities.

  7. Terrestrial Myriametric Radio Burst Observed by IMAGE and Geotail Satellites

    NASA Technical Reports Server (NTRS)

    Fung, Shing F.; Hashimoto, KoZo; Kojima, Hirotsugu; Boardson, Scott A.; Garcia, Leonard N.; Matsumoto, Hiroshi; Green, James L.; Reinisch, Bodo W.

    2013-01-01

    We report the simultaneous detection of a terrestrial myriametric radio burst (TMRB) by IMAGE and Geotail on 19 August 2001. The TMRB was confined in time (0830-1006 UT) and frequency (12-50kHz). Comparisons with all known nonthermal myriametric radiation components reveal that the TMRB might be a distinct radiation with a source that is unrelated to the previously known radiation. Considerations of beaming from spin-modulation analysis and observing satellite and source locations suggest that the TMRB may have a fan beamlike radiation pattern emitted by a discrete, dayside source located along the poleward edge of magnetospheric cusp field lines. TMRB responsiveness to IMF Bz and By orientations suggests that a possible source of the TMRB could be due to dayside magnetic reconnection instigated by northward interplanetary field condition.

  8. Observing and recording instantaneous images on ATM television monitors

    NASA Technical Reports Server (NTRS)

    Patterson, N. P.; Delamere, W. A.; Tousey, R.

    1977-01-01

    A persistent image-converter device was utilized to make visible to the astronaut solar images that were isolated, instantaneous flashes on the ATM TV monitors. In addition, these instantaneous images, as well as normal TV images, were recorded with a Polaroid SX-70 camera for study by the astronauts.

  9. Radio Imaging Observations of Solar Activity Cycle and Its Anomaly

    NASA Astrophysics Data System (ADS)

    Shibasaki, K.

    2011-12-01

    The 24th solar activity cycle has started and relative sunspot numbers are increasing. However, their rate of increase is rather slow compared to previous cycles. Active region sizes are small, lifetime is short, and big (X-class) flares are rare so far. We study this anomalous situation using data from Nobeyama Radioheliograph (NoRH). Radio imaging observations have been done by NoRH since 1992. Nearly 20 years of daily radio images of the Sun at 17 GHz are used to synthesize a radio butterfly diagram. Due to stable operation of the instrument and a robust calibration method, uniform datasets are available covering the whole period of observation. The radio butterfly diagram shows bright features corresponding to active region belts and their migration toward low latitude as the solar cycle progresses. In the present solar activity cycle (24), increase of radio brightness is delayed and slow. There are also bright features around both poles (polar brightening). Their brightness show solar cycle dependence but peaks around solar minimum. Comparison between the last minimum and the previous one shows decrease of its brightness. This corresponds to weakening of polar magnetic field activity between them. In the northern pole, polar brightening is already weakened in 2011, which means it is close to solar maximum in the northern hemisphere. Southern pole does not show such feature yet. Slow rise of activity in active region belt, weakening of polar activity during the minimum, and large north-south asymmetry in polar activity imply that global solar activity and its synchronization are weakening.

  10. Multitemporal observations of sugarcane by TerraSAR-X images.

    PubMed

    Baghdadi, Nicolas; Cresson, Rémi; Todoroff, Pierre; Moinet, Soizic

    2010-01-01

    The objective of this study is to investigate the potential of TerraSAR-X (X-band) in monitoring sugarcane growth on Reunion Island (located in the Indian Ocean). Multi-temporal TerraSAR data acquired at various incidence angles (17°, 31°, 37°, 47°, 58°) and polarizations (HH, HV, VV) were analyzed in order to study the behaviour of SAR (synthetic aperture radar) signal as a function of sugarcane height and NDVI (Normalized Difference Vegetation Index). The potential of TerraSAR for mapping the sugarcane harvest was also studied. Radar signal increased quickly with crop height until a threshold height, which depended on polarization and incidence angle. Beyond this threshold, the signal increased only slightly, remained constant, or even decreased. The threshold height is slightly higher with cross polarization and higher incidence angles (47° in comparison with 17° and 31°). Results also showed that the co-polarizations channels (HH and VV) were well correlated. High correlation between SAR signal and NDVI calculated from SPOT-4/5 images was observed. TerraSAR data showed that after strong rains the soil contribution to the backscattering of sugarcane fields can be important for canes with heights of terminal visible dewlap (htvd) less than 50 cm (total cane heights around 155 cm). This increase in radar signal after strong rains could involve an ambiguity between young and mature canes. Indeed, the radar signal on TerraSAR images acquired in wet soil conditions could be of the same order for fields recently harvested and mature sugarcane fields, making difficult the detection of cuts. Finally, TerraSAR data at high spatial resolution were shown to be useful for monitoring sugarcane harvest when the fields are of small size or when the cut is spread out in time. The comparison between incidence angles of 17°, 37° and 58° shows that 37° is more suitable to monitor the sugarcane harvest. The cut is easily detectable on TerraSAR images for data acquired

  11. Multitemporal Observations of Sugarcane by TerraSAR-X Images

    PubMed Central

    Baghdadi, Nicolas; Cresson, Rémi; Todoroff, Pierre; Moinet, Soizic

    2010-01-01

    The objective of this study is to investigate the potential of TerraSAR-X (X-band) in monitoring sugarcane growth on Reunion Island (located in the Indian Ocean). Multi-temporal TerraSAR data acquired at various incidence angles (17°, 31°, 37°, 47°, 58°) and polarizations (HH, HV, VV) were analyzed in order to study the behaviour of SAR (synthetic aperture radar) signal as a function of sugarcane height and NDVI (Normalized Difference Vegetation Index). The potential of TerraSAR for mapping the sugarcane harvest was also studied. Radar signal increased quickly with crop height until a threshold height, which depended on polarization and incidence angle. Beyond this threshold, the signal increased only slightly, remained constant, or even decreased. The threshold height is slightly higher with cross polarization and higher incidence angles (47° in comparison with 17° and 31°). Results also showed that the co-polarizations channels (HH and VV) were well correlated. High correlation between SAR signal and NDVI calculated from SPOT-4/5 images was observed. TerraSAR data showed that after strong rains the soil contribution to the backscattering of sugarcane fields can be important for canes with heights of terminal visible dewlap (htvd) less than 50 cm (total cane heights around 155 cm). This increase in radar signal after strong rains could involve an ambiguity between young and mature canes. Indeed, the radar signal on TerraSAR images acquired in wet soil conditions could be of the same order for fields recently harvested and mature sugarcane fields, making difficult the detection of cuts. Finally, TerraSAR data at high spatial resolution were shown to be useful for monitoring sugarcane harvest when the fields are of small size or when the cut is spread out in time. The comparison between incidence angles of 17°, 37° and 58° shows that 37° is more suitable to monitor the sugarcane harvest. The cut is easily detectable on TerraSAR images for data acquired

  12. Galileo imaging observations of Lunar Maria and related deposits

    NASA Astrophysics Data System (ADS)

    Greeley, Ronald; Kadel, Steven D.; Williams, David A.; Gaddis, Lisa R.; Head, James W.; McEwen, Alfred S.; Murchie, Scott L.; Nagel, Engelbert; Neukum, Gerhard; Pieters, Carle M.; Sunshine, Jessica M.; Wagner, Roland; Belton, Michael J. S.

    The Galileo spacecraft imaged parts of the western limb and far side of the Moon in December 1990. Ratios of 0.41/0.56 μm filter images from the Solid State Imaging (SSI) experiment provided information on the titanium content of mare deposits; ratios of the 0.76/0.99 μm images indicated 1 μm absorptions associated with Fe2+ in mafic minerals. Mare ages were derived from crater statistics obtained from Lunar Orbiter images. Results on mare compositions in western Oceanus Procellarum and the Humorum basin are consistent with previous Earth-based observations, thus providing confidence in the use of Galileo data to extract compositional information. Mare units in the Grimaldi and Riccioli basins range in age from 3.25 to 3.48 Ga and consist of medium- to medium-high titanium (<4 to 7% TiO2) content lavas. The Schiller-Zucchius basin shows a higher 0.76/0.99 μm ratio than the surrounding highlands, indicating a potentially higher mafic mineral content consistent with previous interpretations that the area includes mare deposits blanketed by highland ejecta and light plains materials. The oldest mare materials in the Orientale basin occur in south-central Mare Orientale and are 3.7 Ga old; youngest mare materials are in Lacus Autumni and are 2.85 Ga old; these units are medium- to medium-high titanium (<4 to 7% TiO2) basalts. Thus, volcanism was active in Orientale for 0.85 Ga, but lavas were relatively constant in composition. Galileo data suggest that Mendel-Rydberg mare is similar to Mare Orientale; cryptomare are present as well. Thus, the mare lavas on the western limb and far side (to 178°E) are remarkably uniform in composition, being generally of medium- to medium-high titanium content and having relatively low 0.76/0.99 μm ratios. This region of the Moon is between two postulated large impact structures, the Procellarum and the South Pole-Aitken basins, and may have a relatively thick crust. In areas underlain by an inferred thinner crust, i.e., zones

  13. WIZARD: A New System for Observing Zodiacal Light

    NASA Astrophysics Data System (ADS)

    Usui, F.; Ishiguro, M.; Kwon, S. M.; Fujino, M.; Lee, C.; Nakamura, R.; Sekiguchi, K.; Miyashita, A.; Nakagiri, M.; Ueno, M.; Mukai, T.

    Zodiacal light is sunlight scattered by the cloud of the interplanetary dust particles in our solar system. By observing the zodiacal light, we can find the origin and evolution of interplanetary dust. We have developed a new system (WIZARD: Wide-field Imager of Zodiacal light with ARray Detector) designed for zodiacal light observation. Since the zodiacal light is faint and wide-spread all over the sky, WIZARD consists of a very sensitive CCD chip and a wide-angle lens with an airglow reduction filter. WIZARD will be able to measure the absolute brightness of diffuse sources in visible wavelengths. Using this instrument, we observed the zodiacal light in 2001 February, March and 2002 March at Mauna Kea, Hawaii (4200 m). In this paper, we report the design and the current performance of the WIZARD system.

  14. Earth Observing-1 Advanced Land Imager: Imaging Performance On-Orbit

    NASA Technical Reports Server (NTRS)

    Hearn, D. R.

    2002-01-01

    This report analyzes the on-orbit imaging performance of the Advanced Land Imager (ALI) on the Earth Observing-1 satellite. The pre-flight calibrations are first summarized. The methods used to reconstruct and geometrically correct the image data from this push-broom sensor are described. The method used here does not refer to the position and attitude telemetry from the spacecraft. Rather, it is assumed that the image of the scene moves across the focal plane with a constant velocity, which can be ascertained from the image data itself. Next, an assortment of the images so reconstructed is presented. Color images sharpened with the 10-m panchromatic band data are shown, and the algorithm for producing them from the 30-m multispectral data is described. The approach taken for assessing spatial resolution is to compare the sharpness of features in the on-orbit image data with profiles predicted on the basis of the pre-flight calibrations. A large assortment of bridge profiles is analyzed, and very good fits to the predicted shapes are obtained. Lunar calibration scans are analyzed to examine the sharpness of the edge-spread function at the limb of the moon. The darkness of the space beyond the limb is better for this purpose than anything that could be simulated on the ground. From these scans, we find clear evidence of scattering in the optical system, as well as some weak ghost images. Scans of planets and stars are also analyzed. Stars are useful point sources of light at all wavelengths, and delineate the point-spread functions of the system. From a quarter-speed scan over the Pleiades, we find that the ALI can detect 6th magnitude stars. The quality of the reconstructed images verifies the capability of the ALI to produce Landsat-type multi spectral data. The signal-to-noise and panchromatic spatial resolution are considerably superior to those of the existing Landsat sensors. The spatial resolution is confirmed to be as good as it was designed to be.

  15. Far-infrared Imaging Observations of the Chamaeleon Region

    NASA Astrophysics Data System (ADS)

    Ikeda, Norio; Kitamura, Yoshimi; Takita, Satoshi; Ueno, Munetaka; Suzuki, Toyoaki; Kawamura, Akiko; Kaneda, Hidehiro

    2012-01-01

    We have carried out far-infrared imaging observations toward the Chamaeleon star-forming region by the Far-Infrared Surveyor (FIS) on board the AKARI satellite. The AKARI images cover a total area of 33.79 deg2, corresponding to 210 pc2 at the distance to the source. Using the FIS bands of 65-160 μm and the COBE/DIRBE bands of 60-240 μm, we constructed column density maps of cold (11.7 K) and warm (22.1 K) dust components with a linear resolution of 0.04 pc. On the basis of their spatial distributions and physical properties, we interpret that the cold component corresponds to the molecular clouds and the warm one the cold H I clouds, which are thought to be in a transient phase between atomic and molecular media. The warm component is shown to be uniformly distributed at a large spatial scale of ~50 pc, while a several pc-scale gradient along the east-west direction is found in the distribution of the cold component. The former is consistent with a formation scenario of the cold H I clouds through the thermal instability in the warm neutral medium triggered by a 100 pc scale supernova explosion. This scenario, however, cannot produce the latter, several pc-scale gradient in molecular cloud mass. We conclude that the gravitational fragmentation of the cold H I cloud likely created the molecular clouds with spatial scale as small as several pc.

  16. FAR-INFRARED IMAGING OBSERVATIONS OF THE CHAMAELEON REGION

    SciTech Connect

    Ikeda, Norio; Kitamura, Yoshimi; Takita, Satoshi; Ueno, Munetaka; Suzuki, Toyoaki

    2012-01-20

    We have carried out far-infrared imaging observations toward the Chamaeleon star-forming region by the Far-Infrared Surveyor (FIS) on board the AKARI satellite. The AKARI images cover a total area of 33.79 deg{sup 2}, corresponding to 210 pc{sup 2} at the distance to the source. Using the FIS bands of 65-160 {mu}m and the COBE/DIRBE bands of 60-240 {mu}m, we constructed column density maps of cold (11.7 K) and warm (22.1 K) dust components with a linear resolution of 0.04 pc. On the basis of their spatial distributions and physical properties, we interpret that the cold component corresponds to the molecular clouds and the warm one the cold H I clouds, which are thought to be in a transient phase between atomic and molecular media. The warm component is shown to be uniformly distributed at a large spatial scale of {approx}50 pc, while a several pc-scale gradient along the east-west direction is found in the distribution of the cold component. The former is consistent with a formation scenario of the cold H I clouds through the thermal instability in the warm neutral medium triggered by a 100 pc scale supernova explosion. This scenario, however, cannot produce the latter, several pc-scale gradient in molecular cloud mass. We conclude that the gravitational fragmentation of the cold H I cloud likely created the molecular clouds with spatial scale as small as several pc.

  17. Spectro-imaging observations of H3+ on Jupiter

    NASA Astrophysics Data System (ADS)

    Lellouch, Emmanuel

    2006-11-01

    Narrow-band filter, high-spectral-resolution (0.2cm-1) spectro-imaging infrared observations of Jupiter's auroral zones, acquired in October 1999 and October 2000 with the FTS/BEAR instrument at the Canada France Hawaii Telescope, have provided maps of the emission from the H2 S1(1) quadrupole line and several H3+ lines. H2 and H3+ emissions appear to be morphologically different, especially in the north, where the latter notably exhibits a ‘hot spot’ near λIII=150 170° System III longitude. The spectra include a total of 14 H3+ lines, including two hot lines from the 3ν2 ν2 band, detected on Jupiter for the first time. They can be used to determine H3+ column densities, rotational (Trot) and vibrational (Tvib) temperatures. We find the mean Tvib of the ν2=3 state to be lower (960±50K) than the mean Trot in v2=2 (1170±75K), indicating an underpopulation of the v2=3 level with respect to local thermodynamical equilibrium. Rotational temperatures and associated column densities are generally higher and lower, respectively, than inferred previously from ν2 observations. These features can be explained by the combination of both a large positive temperature gradient in the sub-microbar auroral atmosphere and non-local thermal equilibrium effects affecting preferentially hot and combination bands. Spatial variations in line intensities are mostly owing to correlated variations in the H3+ column densities. The thermostatic role played by H3+ at ionospheric levels may provide an explanation. The exception is the northern ‘hot spot’, which exhibits a Tvib about 250K higher than other regions.

  18. Lightning Imaging Sensor (LIS) for the Earth Observing System

    NASA Technical Reports Server (NTRS)

    Christian, Hugh J.; Blakeslee, Richard J.; Goodman, Steven J.

    1992-01-01

    Not only are scientific objectives and instrument characteristics given of a calibrated optical LIS for the EOS but also for the Tropical Rainfall Measuring Mission (TRMM) which was designed to acquire and study the distribution and variability of total lightning on a global basis. The LIS can be traced to a lightning mapper sensor planned for flight on the GOES meteorological satellites. The LIS consists of a staring imager optimized to detect and locate lightning. The LIS will detect and locate lightning with storm scale resolution (i.e., 5 to 10 km) over a large region of the Earth's surface along the orbital track of the satellite, mark the time of occurrence of the lightning, and measure the radiant energy. The LIS will have a nearly uniform 90 pct. detection efficiency within the area viewed by the sensor, and will detect intracloud and cloud-to-ground discharges during day and night conditions. Also, the LIS will monitor individual storms and storm systems long enough to obtain a measure of the lightning flashing rate when they are within the field of view of the LIS. The LIS attributes include low cost, low weight and power, low data rate, and important science. The LIS will study the hydrological cycle, general circulation and sea surface temperature variations, along with examinations of the electrical coupling of thunderstorms with the ionosphere and magnetosphere, and observations and modeling of the global electric circuit.

  19. Satellite observations and instrumentation for imaging energetic neutral atoms

    NASA Astrophysics Data System (ADS)

    Voss, Henry D.; Mobilia, Joseph; Collin, Henry L.; Imhof, William L.

    1992-06-01

    Direct measurements of energetic neutral atoms (ENA) and ions have been obtained with the cooled solid state detectors on the low altitude (220 km) three-axis stabilized S81-1/SEEP satellite and on the spinning 400 km X 5.5 Re CRRES satellite. During magnetic storms ENA and ion precipitation (E > 10 keV) is evident over the equatorial region from the LE spectrometer on the SEEP payload (ONR 804). The spinning motion of the CRRES satellite allows for simple mapping of the magnetosphere using the IMS-HI (ONR 307-8-3) neutral spectrometer. This instrument covers the energy range from 20 to 1000 keV and uses a 7 kG magnetic field to screen out protons less than about 50 MeV. ENA and the resulting low- altitude ion belt have been observed with the IMS-HI instrument. Recently, an advanced spectrometer (SEPS) has been developed to image electrons, ions, and neutrals on the despun platform of the POLAR satellite (approximately 1.8 X 9 Re) for launch in the mid-90's as part of the NASA ISTP/GGS program. For this instrument a 256 element solid state pixel array has been developed that interfaces to 256 amplifier strings using a custom 16 channel microcircuit chip. In addition, this instrument features a motor controlled iris wheel and anticoincidence electronics.

  20. [Right ventricular dysplasia and dilated cardiomyopathy observed by radionuclide images].

    PubMed

    Takamura, I; Ando, J; Miyamoto, A; Kobayashi, T; Sakamoto, S; Yasuda, H

    1985-12-01

    Four cases of right ventricular dysplasia (RVD) and 28 cases of dilated cardiomyopathy (DCM) were studied. RVD was characterized clinically by syncope, sustained recurrent ventricular tachycardia with left bundle branch block patterns on the surface electrocardiogram, and right heart failure. Furthermore, moderate to severe dilatation of the right ventricle and depressed right ventricular function were apparent on radionuclide angiography. However, left ventricular dilatation and depressed left ventricular function were documented in DCM. Right ventricular volume was proportional to left ventricular volume in DCM, however, right ventricular volume was disproportionately greater in RVD. On the T1-201 perfusion image, left ventricular perfusion defects were delineated in 10 of 26 patients with DCM, and in one of four RVD patients. During two to eight year follow-up periods, six patients died suddenly five of whom had left ventricular perfusion defects. However, in 19 patients without left ventricular perfusion defects, only one sudden death was observed. A connecting link between sudden death and left ventricular perfusion defect is suggested. PMID:3841888

  1. Observations and modeling of the coupled latitude-altitude patterns of equatorial plasma depletions

    NASA Astrophysics Data System (ADS)

    Mendillo, Michael; Zesta, Eftyhia; Shodhan, Sheela; Sultan, Peter J.; Doe, Richard; Sahai, Yogeshwar; Baumgardner, Jeffrey

    2005-09-01

    The equatorial ionosphere is host to the most dramatic and enigmatic plasma instability mechanism in the geospace environment. Equatorial spread F (ESF) was discovered in early ionosonde measurements and interpreted theoretically using Rayleigh-Taylor theory. Subsequent diagnostic and modeling advances have improved substantially our understanding of ESF onset and evolution and its associated effects on the ionosphere throughout the low-latitude domain. The degree to which ESF mechanisms penetrate into the lower midlatitudes is a topic of current study, a reverse of the familiar concept of high-to-low latitude coupling for space weather phenomena. Optical diagnostic systems, first ground based and now space based, reveal the presence of ESF structures via images of airglow depletions that are aligned in the approximately north-south direction spanning the geomagnetic equator. Ground-based all-sky camera systems used to capture the two-dimensional horizontal patterns of airglow depletions are the main source of observations showing that ESF processes intrude to midlatitudes in the L ˜ 1.5 domain. In this paper we review the process of mapping airglow depletions along geomagnetic field lines to the equatorial plane, hence defining the maximum apex heights achieved. A case study comparison of simultaneous radar backscatter data from Kwajalein with optical data from Wake Island, sites that share common magnetic meridians in the Pacific section, confirms the utility of the approach and its applicability to sites at other longitudes. Modeling studies based on buoyancy arguments using flux tube-integrated mean density values versus L shell apex heights show that instability-induced plasma depletions starting at F layer bottomside heights easily reach altitudes above 2000 km in the equatorial plane, implying that ESF intrusions to lower midlatitudes should be a relatively frequent occurrence.

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

    PubMed

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

    2014-09-10

    Over the past 60 years, ground-based remote sensing measurements of the Earth's mesospheric temperature have been performed using the nighttime hydroxyl (OH) emission, which originates at an altitude of ∼87  km. Several types of instruments have been employed to date: spectrometers, Fabry-Perot or Michelson interferometers, scanning-radiometers, and more recently temperature mappers. Most of them measure the mesospheric temperature in a few sample directions and/or with a limited temporal resolution, restricting their research capabilities to the investigation of larger-scale perturbations such as inertial waves, tides, or planetary waves. The Advanced Mesospheric Temperature Mapper (AMTM) is a novel infrared digital imaging system that measures selected emission lines in the mesospheric OH (3,1) band (at ∼1.5  μm) to create intensity and temperature maps of the mesosphere around 87 km. The data are obtained with an unprecedented spatial (∼0.5  km) and temporal (typically 30″) resolution over a large 120° field of view, allowing detailed measurements of wave propagation and dissipation at the ∼87  km level, even in the presence of strong aurora or under full moon conditions. This paper describes the AMTM characteristics, compares measured temperatures with values obtained by a collocated Na lidar instrument, and presents several examples of temperature maps and nightly keogram representations to illustrate the excellent capabilities of this new instrument. PMID:25321674

  3. Visualization tools for the processing of airglow data from RAIDS

    NASA Technical Reports Server (NTRS)

    Miller, Gordon J.; Thonnard, Stefan; Picone, Michael; Meesuk, Carolyn

    1995-01-01

    In anticipation of large data sets associated with a number of atmospheric imaging instruments being prepared for long term global coverage, NRL is developing graphical interfaces for all aspects of the program. For the first of these projects, RAIDS (the Remote Atmospheric and Ionospheric Detection System), a graphical approach to data handling, visualization, and analysis is envisioned and will set the stage for the satellites that follow. An overall system of hardware and a set of software 'tools,' that will allow for both the routine handling of all data and the analysis of large data sets assembled by scientists and instrument engineers, are currently being developed. The software for standard processing and visualization of instrument data is independent of computer platform and will allow for easy adaptation from one experiment to another. The processing will produce data sets that have similar characteristics, allowing for easy comparison of data obtained under similar circumstances. The visualization of both the engineering and scientific data is an important part of the system. By creating graphical environments for engineering evaluations and for scientific analysis data sets can be viewed and analyzed rapidly. This rapid analysis of data will contribute towards a greater portion of the RAIDS data being utilized.

  4. Calibration of the San Marco airglow-solar spectrometer instrument in the extreme ultraviolet

    NASA Astrophysics Data System (ADS)

    Worden, John; Woods, Thomas N.; Rottman, Gary J.; Schmidtke, Gerhard; Tai, Hongsheng; Doll, Harry G.; Solomon, Stanley C.

    1996-02-01

    The San Marco 5 carried the airglow-solar spectrometer instrument (ASSI). This 18-channel spectrometer measured the solar and terrestrial radiation in the wavelength region between 20 and 700 nm for 9 months in 1988. The ASSI extreme ultraviolet (EUV) channels showed significant sensitivity changes during the mission. The sensitivity changes of the EUV channels are quantified by comparing ASSI solar EUV irradiance measurements to the solar EUV irradiance derived from a solar proxy model. A sensitivity change model is developed that shows that exponential curves can adequately describe the sensitivity changes of the ASSI optics and detectors. The November 10 calibration parameters and the sensitivity change model can be used to derive the EUV terrestrial airglow brightness for the time period of the ASSI mission. Analysis of the solar Lyman-(alpha) irradiance measured by the ASSI, the solar mesospheric explorer (SME), and the upper atmosphere research satellite has led to a revised Lyman-(alpha) irradiance for the San Marco mission. For example, the ASSI November 10, 1988, Lyman-(alpha) measurement is 5.3 X 1011 photons cm-2 s-1 versus the reported SME measurement of 3.35 X 1011 photons cm-2 s-1.

  5. SWIR Hemispherical Air-Glow Plotting System SHAPS

    NASA Astrophysics Data System (ADS)

    Gonglewski, John D.; Myers, Michael M.; Dayton, David C.; Fertig, Gregory; Allen, Jeffrey; Nolasco, Rudolph; Maia, Franscisco

    2010-10-01

    It is well known that luminance from photo-chemical reactions of hydroxyl ions in the upper atmosphere (~85 km altitude) produces a significant amount of night time radiation in the short wave infra-red (SWIR) band of wave length 0.9 to 1.7 μm. Numerous studies of these phenomena have demonstrated that the irradiance shows significant temporal and spatial variations in the night sky. Changes in weather patterns, seasons, sun angle, moonlight, etc have the propensity to alter the SWIR air glow irradiance pattern. By performing multiple SWIR measurements a mosaic representation of the celestial hemisphere was constructed and used to investigate these variations over time and space. The experimental setup consisted of two sensors, an InGaAs SWIR detector and a visible astronomical camera, co-located and bore sighted on an AZ-EL gimbal. This gimbal was programmed to view most of the sky using forty five discrete azimuth and elevation locations. The dwell time at each location was 30 seconds with a total cycle time of less than 30 minutes. The visible astronomical camera collected image data simultaneous with the SWIR camera in order to distinguish SWIR patterns from clouds. Data was reduced through batch processing producing polar representations of the sky irradiance as a function of azimuth, elevation, and time. These spatiotemporal variations in the irradiance, both short and long term, can be used to validate and calibrate physical models of atmospheric chemistry and turbulence. In this paper we describe our experimental setup and present some results of our measurements made over several months in a rural marine environment on the Island of Kauai Hawaii.

  6. Observation of pressure ridges in SAR images of sea ice: Scattering theory and comparison with observations

    NASA Technical Reports Server (NTRS)

    Vesecky, J. F.; Daida, J. M.; Shuchman, R. A.; Onstott, R. H.; Camiso, J. C.

    1993-01-01

    Ridges and keels (hummocks and bummocks) in sea ice flows are important in sea ice research for both scientific and practical reasons. Sea ice movement and deformation is driven by internal and external stresses on the ice. Ridges and keels play important roles in both cases because they determine the external wind and current stresses via drag coefficients. For example, the drag coefficient over sea ice can vary by a factor of several depending on the fluid mechanical roughness length of the surface. This roughness length is thought to be strongly dependent on the ridge structures present. Thus, variations in ridge and keel structure can cause gradients in external stresses which must be balanced by internal stresses and possibly fracture of the ice. Ridging in sea ice is also a sign of fracture. In a practical sense, large ridges form the biggest impediment to surface travel over the ice or penetration through sea ice by ice-strengthened ships. Ridges also play an important role in the damage caused by sea ice to off-shore structures. Hence, observation and measurement of sea ice ridges is an important component of sea ice remote sensing. The research reported here builds on previous work, estimating the characteristics of ridges and leads in sea ice from SAR images. Our objective is to develop methods for quantitative measurement of sea ice ridges from SAR images. To make further progress, in particular, to estimate ridge height, a scattering model for ridges is needed. Our research approach for a ridge scattering model begins with a survey of the geometrical properties of ridges and a comparison with the characteristics of the surrounding ice. For this purpose we have used airborne optical laser (AOL) data collected during the 1987 Greenland Sea Experiment. These data were used to generate a spatial wavenumber spectrum for height variance for a typical ridge - the typical ridge is the average over 10 large ridges. Our first-order model radar scattering includes

  7. Observation of pressure ridges in SAR images of sea ice: Scattering theory and comparison with observations

    NASA Astrophysics Data System (ADS)

    Vesecky, J. F.; Daida, J. M.; Shuchman, R. A.; Onstott, R. H.; Camiso, J. C.

    Ridges and keels (hummocks and bummocks) in sea ice flows are important in sea ice research for both scientific and practical reasons. Sea ice movement and deformation is driven by internal and external stresses on the ice. Ridges and keels play important roles in both cases because they determine the external wind and current stresses via drag coefficients. For example, the drag coefficient over sea ice can vary by a factor of several depending on the fluid mechanical roughness length of the surface. This roughness length is thought to be strongly dependent on the ridge structures present. Thus, variations in ridge and keel structure can cause gradients in external stresses which must be balanced by internal stresses and possibly fracture of the ice. Ridging in sea ice is also a sign of fracture. In a practical sense, large ridges form the biggest impediment to surface travel over the ice or penetration through sea ice by ice-strengthened ships. Ridges also play an important role in the damage caused by sea ice to off-shore structures. Hence, observation and measurement of sea ice ridges is an important component of sea ice remote sensing. The research reported here builds on previous work, estimating the characteristics of ridges and leads in sea ice from SAR images. Our objective is to develop methods for quantitative measurement of sea ice ridges from SAR images. To make further progress, in particular, to estimate ridge height, a scattering model for ridges is needed. Our research approach for a ridge scattering model begins with a survey of the geometrical properties of ridges and a comparison with the characteristics of the surrounding ice. For this purpose we have used airborne optical laser (AOL) data collected during the 1987 Greenland Sea Experiment. These data were used to generate a spatial wavenumber spectrum for height variance for a typical ridge - the typical ridge is the average over 10 large ridges. Our first-order model radar scattering includes

  8. Curiosity's Mars Hand Lens Imager (MAHLI): Inital Observations and Activities

    NASA Technical Reports Server (NTRS)

    Edgett, K. S.; Yingst, R. A.; Minitti, M. E.; Robinson, M. L.; Kennedy, M. R.; Lipkaman, L. J.; Jensen, E. H.; Anderson, R. C.; Bean, K. M.; Beegle, L. W.; Carsten, J. L.; Collins, C. L.; Cooper, B.; Deen, R. G.; Gupta, S.

    2013-01-01

    MAHLI (Mars Hand Lens Imager) is a 2-megapixel focusable macro lens color camera on the turret on Curiosity's robotic arm. The investigation centers on stratigraphy, grain-scale texture, structure, mineralogy, and morphology of geologic materials at Curiosity's Gale robotic field site. MAHLI acquires focused images at working distances of 2.1 cm to infinity; for reference, at 2.1 cm the scale is 14 microns/pixel; at 6.9 cm it is 31 microns/pixel, like the Spirit and Opportunity Microscopic Imager (MI) cameras.

  9. Gemini planet imager observational calibrations VII: on-sky polarimetric performance of the Gemini planet imager

    NASA Astrophysics Data System (ADS)

    Wiktorowicz, Sloane J.; Millar-Blanchaer, Max; Perrin, Marshall D.; Graham, James R.; Fitzgerald, Michael P.; Maire, Jérôme; Ingraham, Patrick; Savransky, Dmitry; Macintosh, Bruce A.; Thomas, Sandrine J.; Chilcote, Jeffrey K.; Draper, Zachary H.; Song, Inseok; Cardwell, Andrew; Goodsell, Stephen J.; Hartung, Markus; Hibon, Pascale; Rantakyrö, Fredrik; Sadakuni, Naru

    2014-07-01

    We present on-sky polarimetric observations with the Gemini Planet Imager (GPI) obtained at straight Cassegrain focus on the Gemini South 8-m telescope. Observations of polarimetric calibrator stars, ranging from nearly un- polarized to strongly polarized, enable determination of the combined telescope and instrumental polarization. We find the conversion of Stokes I to linear and circular instrumental polarization in the instrument frame to be I --> (QIP, UIP, PIP, VIP) = (-0.037 +/- 0.010%, +0.4338 +/- 0.0075%, 0.4354 +/- 0.0075%, -6.64 +/- 0.56%). Such precise measurement of instrumental polarization enables ~0.1% absolute accuracy in measurements of linear polarization, which together with GPI's high contrast will allow GPI to explore scattered light from circumstellar disk in unprecedented detail, conduct observations of a range of other astronomical bodies, and potentially even study polarized thermal emission from young exoplanets. Observations of unpolarized standard stars also let us quantify how well GPI's differential polarimetry mode can suppress the stellar PSF halo. We show that GPI polarimetry achieves cancellation of unpolarized starlight by factors of 100-200, reaching the photon noise limit for sensitivity to circumstellar scattered light for all but the smallest separations at which the calibration for instrumental polarization currently sets the limit.

  10. Observation of a mesospheric front in a dual duct over King George Island, Antarctica

    NASA Astrophysics Data System (ADS)

    Bageston, J. V.; Wrasse, C. M.; Batista, P. P.; Hibbins, R. E.; Fritts, D. C.; Gobbi, D.; Andrioli, V. F.

    2011-05-01

    A mesospheric bore was observed with an all-sky airglow imager on the night of 9-10 July 2007 at Ferraz Station (62° S, 58° W), located on King George island on the Antarctic Peninsula. The observed bore propagated from southwest to northeast with a well defined wave front and a series of crests behind the main front. There was no evidence of dissipation during its propagation within the field of view. The wave parameters were obtained via a 2-D Fourier transform of the imager data providing a horizontal wavelength of 33 km, an observed period of 6 min, and a horizontal phase speed of 92 m s-1. Simultaneous mesospheric winds were measured with a medium frequency (MF) radar at Rothera Station (68° S, 68° W) and temperature profiles were obtained from the SABER instrument on the TIMED satellite. These wind and temperature profiles were used to estimate the propagation environment of the bore. A wavelet technique was applied to the wind in the plane of bore propagation at the OH emission height spanning three days centered on the bore event to define the dominant periodicities. Results revealed a dominance of near-inertial periods, and semi-diurnal and terdiurnal tides suggesting that the ducting structure enabling bore propagation occurred on large spatial scales. The observed tidal motions were used to reconstruct the winds employing a least-squares method, which were then compared to the observed ducting environment. Results suggest an important contribution of large-scale winds to the ducting structure, but with buoyancy frequency variations in the vertical also expected to be important. These results allow us to conclude that the bore was supported by a duct including contributions from both winds and temperature (or stability). A co-located airglow temperature imager operated simultaneously with the all-sky imager confirmed that the bore event was the dominant small-scale wave event during the analysis interval.

  11. Novel Stimulated Electromagnetic Emission Observations with Artificial Airglow Using RF Excitation with HAARP

    NASA Astrophysics Data System (ADS)

    Briczinski, S. J., Jr.; Bernhardt, P. A.; Siefring, C. L.; Michell, R.; Hampton, D. L.; Watkins, B. J.; Bristow, W. A.

    2014-12-01

    Neutral hydrogen plays an important role in determining the state of the plasmasphere and its response to forcing from geomagnetic storms. Hydrogen's solar cycle variation is counterintuitive: there is more hydrogen at solar minimum at 300 km that there is at solar maximum. Similarly there is more hydrogen in winter than in summer and hydrogen density maximizes in the morning. In this presentation we describe these variations and consider some possible causes for them.

  12. Observations of Beta Pictoris b with the Gemini Planet Imager

    NASA Astrophysics Data System (ADS)

    Chilcote, J.; Graham, J.; Barman, T.; Fitzgerald, M.; Larkin, J.; Macintosh, B.; Bauman, B.; Burrows, A.; Cardwell, A.; De Rosa, R.; Dillon, D.; Doyon, R.; Dunn, J.; Erikson, D.; Gavel, D.; Goodsell, S.; Hartung, M.; Hibon, P.; Ingraham, P.; Kalas, P.; Konopacky, Q.; Maire, J.; Marchis, F.; Marley, M.; Mcbride, J.; Millar-Blanchaer, M.; Morzinski, K.; Norton, A.; Oppenheimer, B.; Palmer, D.; Patience, J.; Pueyo, L.; Rantakyro, F.; Sadakuni, N.; Saddlemyer, L.; Savransky, D.; Serio, A.; Soummer, R.; Sivaramakrishnan, A.; Song, I.; Thomas, S.; Wallace, K.; Wiktorowicz, S.; Wolff, S.

    2014-09-01

    Using the recently installed Gemini Planet Imager (GPI), we present measurements of the planetary companion to the nearby young star beta Pic. GPI is a facility class instrument located at Gemini South designed to image and provide low-resolution spectra of Jupiter sized, self-luminous planetary companions around young nearby stars. We present the current imaged spectrum and atmospheric models of the planet based upon GPI's R ˜50 integral field spectrograph. Further, we present a joint analysis of the GPI and NACO astrometry, and the Snellen et al. (2014) radial velocity measurement of beta Pic b that provides the first constraint on the argument of periastron, providing a causal link to the infalling, evaporating bodies.

  13. Dust Transport and Deposition Observed from the Terra-Moderate Image Spectrometer (MODIS) Space Observations

    NASA Technical Reports Server (NTRS)

    Kaufman, Y.

    2004-01-01

    Meteorological observations, in situ data and satellite images of dust episodes were used already in the 1970s to estimate that 100 tg of dust are transported from Africa over the Atlantic Ocean every year between June and August and deposited in the Atlantic Ocean and the Americas. Desert dust is a main source of nutrients to oceanic biota and the Amazon forest, but deteriorates air quality and caries pathogens as shown for Florida. Dust affects the Earth radiation budget, thus participating in climate change and feedback mechanisms. There is an urgent need for new tools for quantitative evaluation of the dust distribution, transport and deposition. The Terra spacecraft launched at the dawn of the last millennium provides first systematic well calibrated multispectral measurements from the MODIS instrument, for daily global analysis of aerosol. MODIS data are used here to distinguish dust from smoke and maritime aerosols and evaluate the African dust column concentration, transport and deposition. We found that 230 plus or minus 80 tg of dust are transported annually from Africa to the Atlantic Ocean, 30 tg return to Africa and Europe, 70 tg reach the Caribbean, 45 tg fertilize the Amazon Basin, 4 times as previous estimates thus explaining a paradox regarding the source of nutrition to the Amazon forest, and 120 plus or minus 40 tg are deposited in the Atlantic Ocean. The results are compared favorably with dust transport models for particle radius less than or equal to 12 microns. This study is a first example of quantitative use of MODIS aerosol for a geophysical study.

  14. Ultraviolet Imaging Telescope observations of the Crab Nebula

    NASA Technical Reports Server (NTRS)

    Hennessy, Gregory S.; O'Connell, Robert W.; Cheng, Kwang P.; Bohlin, Ralph C.; Collins, Nicholas R.; Gull, Theodore P.; Hintzen, Paul; Isensee, Joan E.; Landsman, Wayne B.; Roberts, Morton S.

    1992-01-01

    We obtained ultraviolet images of the Crab Nebula with the Ultraviolet Imaging Telescope during the Astro-1 Space Shuttle mission in 1990 December. The UV continuum morphology of the Crab is generally similar to that in the optical region, but the wispy structures are less conspicuous in the UV and X-ray. UV line emission from the thermal filaments is not strong. UV spectral index maps with a resolution of 10 arcsecs show a significant gradient across the nebula, with the outer parts being redder, as expected from synchrotron losses. The location of the bluest synchrotron continuum does not coincide with the pulsar.

  15. Ultraviolet Imaging Telescope observations of the Crab Nebula

    NASA Astrophysics Data System (ADS)

    Hennessy, Gregory S.; O'Connell, Robert W.; Cheng, Kwang P.; Bohlin, Ralph C.; Collins, Nicholas R.; Gull, Theodore R.; Hintzen, Paul; Isensee, Joan E.; Landsman, Wayne B.; Roberts, Morton S.; Smith, Andrew M.; Smith, Eric P.; Stecher, Theodore P.

    1992-08-01

    We obtained ultraviolet images of the Crab Nebula with the Ultraviolet Imaging Telescope during the Astro-1 Space Shuttle mission in 1990 December. The UV continuum morphology of the Crab is generally similar to that in the optical region, but the wispy structures are less conspicuous in the UV and X-ray. UV line emission from the thermal filaments is not strong. UV spectral index maps with a resolution of 10 arcsecs show a significant gradient across the nebula, with the outer parts being redder, as expected from synchrotron losses. The location of the bluest synchrotron continuum does not coincide with the pulsar.

  16. Lunar and Planetary Science XXXV: Image Processing and Earth Observations

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The titles in this section include: 1) Expansion in Geographic Information Services for PIGWAD; 2) Modernization of the Integrated Software for Imagers and Spectrometers; 3) Science-based Region-of-Interest Image Compression; 4) Topographic Analysis with a Stereo Matching Tool Kit; 5) Central Avra Valley Storage and Recovery Project (CAVSARP) Site, Tucson, Arizona: Floodwater and Soil Moisture Investigations with Extraterrestrial Applications; 6) ASE Floodwater Classifier Development for EO-1 HYPERION Imagery; 7) Autonomous Sciencecraft Experiment (ASE) Operations on EO-1 in 2004; 8) Autonomous Vegetation Cover Scene Classification of EO-1 Hyperion Hyperspectral Data; 9) Long-Term Continental Areal Reduction Produced by Tectonic Processes.

  17. Observer performance with computer-generated images of /sup 201/Tl-Cl myocardial perfusion

    SciTech Connect

    Wiener, S.N.; Flynn, M.J.; Edelstein, J.

    1980-07-01

    The effect of simple image processing on the interpretation of /sup 201/Tl-Cl myocardial perfusion images was evaluated by ROC analysis. Polaroid images of the cathode ray tube of an Anger camera and computer-processed transparent images recorded in color and shades of gray were examined by multiple observers. A total of 198 observer responses was accumulated for each of five image formats. The observer responses were compared with results established by coronary angiography. Better observer performance was obtained for all computer-generated images except in the region of low false positive values. The response for color-scale formats were, in general, superior to those from the gray-scale formats. No significant improvement in observer performance resulted from the use of background subtraction with a rescaling of the 16-level gray scale to the residual information. When nine-point smoothing was applied to the color-scale display format, there was a poorer observer response.

  18. T he Analysis of the seasonal variations of equatorial plasma bubble, occurrence observed from Oukaimeden Observatory, Morroco

    NASA Astrophysics Data System (ADS)

    Amine, Lagheryeb; Zouhair, Benkhaldoun; Jonathan, Makela; Mohamed, Kaab; Aziza, Bounhir; Brian, Hardin; Dan, Fisher; Tmuthy, Duly

    2016-04-01

    T he Analysis of the seasonal variations of equatorial plasma bubble, occurrence using the 630.0 nm airglow images collected by the PICASSO imager deployed at the Oukkaimden observatory in Morocco. Data have been taken since November 2013 to december 2015. We show the monthly average of appearance of EPBs. A maximum probability for bubble development is seen in the data in January and between late February and early March. We also observe that there are a maximum period of appearance where the plasma is observed (3-5 nights successivies) and we will discuss its connection with the solar activity in storm time. Future analysis will compare the probability of bubble occurrence in our site with the data raised in other observation sites.

  19. Advanced scanners and imaging systems for earth observations. [conferences

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Assessments of present and future sensors and sensor related technology are reported along with a description of user needs and applications. Five areas are outlined: (1) electromechanical scanners, (2) self-scanned solid state sensors, (3) electron beam imagers, (4) sensor related technology, and (5) user applications. Recommendations, charts, system designs, technical approaches, and bibliographies are included for each area.

  20. Cassini Imaging Science Subsystem observations of Titan's south polar cloud

    NASA Astrophysics Data System (ADS)

    West, R. A.; Del Genio, A. D.; Barbara, J. M.; Toledo, D.; Lavvas, P.; Rannou, P.; Turtle, E. P.; Perry, J.

    2016-05-01

    In May of 2012 images of Titan obtained by the Cassini Imaging Science Subsystem (ISS) showed a newly-formed cloud patch near the southern pole. The cloud has unusual morphology and texture suggesting that it is formed by condensation at an altitude much higher than expected for any of the known organics in Titan's atmosphere. We measured the altitude to be 300 ± 10 km from images when the feature was on the limb. Limb images suggest that the initial stages of the formation began in late 2011. It was just visible in images obtained in 2014 but is not expected to be visible in the future due to enveloping darkness as the season progresses. The feature has a slightly different color than the surrounding haze. Its optical thickness is near 2 at 889 nm wavelength and the particle imaginary refractive index must be less than 5 × 10-4 at that wavelength. Wind vectors derived from a time series show that it is rotating about a center offset by 4.5° from Titan's solid-body spin axis, consistent with that found from the temperature field by Achterberg et al. (Achterberg, R.K., Conrath, B.J., Gierasch, P.J., Flasar, F.M., Nixon, C.A. [2008a]. Icarus 197, 549-555) and subsequent measurements. The feature rotates at an angular velocity near the rate expected for transport of angular momentum from the low latitudes to the pole. The clumpy texture of the feature resembles that of terrestrial cloud fields undergoing open cell convection, an unusual configuration initiated by downwelling.

  1. Observation angle and plane characterisation for ISAR imaging of LEO space objects

    NASA Astrophysics Data System (ADS)

    Chen, Jin; Fu, Tuo; Chen, Defeng; Gao, Meiguo

    2016-07-01

    For inverse synthetic aperture radar (ISAR) imaging of low Earth orbit (LEO) space objects, examining the variations in the image plane of the object over the entire visible arc period allows more direct characterisation of the variations in the object imaging. In this study, the ideal turntable model was extended to determine the observation geometry of near-circular LEO objects. Two approximations were applied to the observation model to calculate the image plane's normal and observation angles for near-circular orbit objects. One approximation treats the orbit of the space object as a standard arc relative to the Earth during the radar observation period, and the other omits the effect of the rotation of the Earth on the observations. First, the closed-form solution of the image plane normal in various attitude-stabilisation approaches was determined based on geometric models. The characteristics of the image plane and the observation angle of the near-circular orbit object were then analysed based on the common constraints of the radar line-of-sight (LOS). Subsequently, the variations in the image plane and the geometric constraints of the ISAR imaging were quantified. Based on the image plane's normal, the rotational angular velocity of the radar LOS was estimated. The cross-range direction of the ISAR image was then calibrated. Three-dimensional imaging was then reconstructed based on dual station interferometry. Finally, simulations were performed to verify the result of the three-dimensional interferometric reconstruction and to calculate the reconstruction's precision errors.

  2. The nonlinear thermodynamics of meteors, noctilucent clouds, enhanced airglow and global atmospheric circulation

    NASA Technical Reports Server (NTRS)

    Rajchl, J.

    1987-01-01

    Two types of fundamental topological junctions of elements are deduced from a nonlinear thermodynamical model. Using this scheme, the possibility of a causal relation between fireballs and faint meteors as nonlinear sources on the one hand, and noctilucent clouds (NC) and Hoffmeister's enhanced airglow (EA) as complementary formative processes in the middle atmosphere and ionosphere, on the other hand, is examined. The principal role of the global atmospheric circulation in this relation is demonstrated. Such circulation in the mesosphere appears to prevent the neutral dust dissipated by fireballs from becoming an efficient agent in NLC generation. In this case, the behavior of ionized material deposited by both the bright and faint meteors is more probably controlled, as shown from the annual variation of the E sub s layer by the darkness of lunar eclipses and the global circulation of the lower thermosphere. The role of fireballs and neutral dust might be more significant as a source of EA phenomenon.

  3. A procedure for the extraction of airglow features in the presence of strong background radiation

    NASA Astrophysics Data System (ADS)

    Swift, W. R.; Torr, D. G.; Hamilton, C.; Dougani, H.; Torr, M. R.

    1990-09-01

    A technique is developed that can be used to derive the total intensity of band emissions from twilight airglow measurements when the basic spectral signature of the band to be considered is known. The method is designed to automatically extract total band or line intensities of a signal imbedded in background radiation several orders of magnitude greater in brightness. It is shown that the technique developed can reliably measure the intensity of both weak and strong band and line emissions in the presence of strong twilight background radiation. The method of extraction is shown as part of a general purpose spectral analysis program written in VAX FORTRAN. This extraction procedure has been used successfully on emissions of Fel, Ca(+), N2(+) (1N) (0-0) and (0-1), OH in the near UV. OI red (630nm) and green (558nm) lines in the visible, and the OH Meinel bands and O(+) (2P) 732 nm in the near IR.

  4. Global Observation Information Networking: Using the Distributed Image Spreadsheet (DISS)

    NASA Technical Reports Server (NTRS)

    Hasler, Fritz

    1999-01-01

    The DISS and many other tools will be used to present visualizations which span the period from the original Suomi/Hasler animations of the first ATS-1 GEO weather satellite images in 1966 ....... to the latest 1999 NASA Earth Science Vision for the next 25 years. Hot off the SGI Onyx Graphics-Supercomputers are NASA's visualizations of Hurricanes Mitch, Georges, Fran and Linda. These storms have been recently featured on the covers of National Geographic, Time, Newsweek and Popular Science and used repeatedly this season on National and International network TV. Results will be presented from a new paper on automatic wind measurements in Hurricane Luis from 1-min GOES images that appeared in the November BAMS.

  5. Stellar Imager - Observing the Universe in High Definition

    NASA Technical Reports Server (NTRS)

    Carpenter, Kenneth

    2009-01-01

    Stellar Imager (SI) is a space-based, UV Optical Interferometer (UVOI) with over 200x the resolution of HST. It will enable 0.1 milli-arcsec spectral imaging of stellar surfaces and the Universe in general and open an enormous new 'discovery space' for Astrophysics with its combination of high angular resolution, dynamic imaging, and spectral energy resolution. SI's goal is to study the role of magnetism in the Universe and revolutionize our understanding of: 1) Solar/Stellar Magnetic Activity and their impact on Space Weather, Planetary Climates. and Life, 2) Magnetic and Accretion Processes and their roles in the Origin and Evolution of Structure and in the Transport of Matter throughout the Universe, 3) the close-in structure of Active Galactic Nuclei and their winds, and 4) Exo-Solar Planet Transits and Disks. The SI mission is targeted for the mid 2020's - thus significant technology development in the upcoming decade is critical to enabling it and future spacebased sparse aperture telescope and distributed spacecraft missions. The key technology needs include: 1) precision formation flying of many spacecraft, 2) precision metrology over km-scales, 3) closed-loop control of many-element, sparse optical arrays, 4) staged-control systems with very high dynamic ranges (nm to km-scale). It is critical that the importance of timely development of these capabilities is called out in the upcoming Astrophysics and Heliophysics Decadal Surveys, to enable the flight of such missions in the following decade. S1 is a 'Landmark/Discovery Mission' in 2005 Heliophysics Roadmap and a candidate UVOI in the 2006 Astrophysics Strategic Plan. It is a NASA Vision Mission ('NASA Space Science Vision Missions' (2008), ed. M. Allen) and has also been recommended for further study in the 2008 NRC interim report on missions potentially enabled enhanced by an Ares V' launch, although a incrementally-deployed version could be launched using smaller rockets.

  6. Imaging-based observational databases for clinical problem solving: the role of informatics

    PubMed Central

    Bui, Alex A T; Hsu, William; Arnold, Corey; El-Saden, Suzie; Aberle, Denise R; Taira, Ricky K

    2013-01-01

    Imaging has become a prevalent tool in the diagnosis and treatment of many diseases, providing a unique in vivo, multi-scale view of anatomic and physiologic processes. With the increased use of imaging and its progressive technical advances, the role of imaging informatics is now evolving—from one of managing images, to one of integrating the full scope of clinical information needed to contextualize and link observations across phenotypic and genotypic scales. Several challenges exist for imaging informatics, including the need for methods to transform clinical imaging studies and associated data into structured information that can be organized and analyzed. We examine some of these challenges in establishing imaging-based observational databases that can support the creation of comprehensive disease models. The development of these databases and ensuing models can aid in medical decision making and knowledge discovery and ultimately, transform the use of imaging to support individually-tailored patient care. PMID:23775172

  7. Planetary instrument definition and development program: 'Miniature Monochromatic Imager'

    NASA Technical Reports Server (NTRS)

    Broadfoot, A. L.

    1991-01-01

    The miniature monochromatic imager (MMI) development work became the basis for the preparation of several instruments which were built and flown on the shuttle STS-39 as well as being used in ground based experiments. The following subject areas are covered: (1) applications of the ICCD to airglow and auroral measurements and (2) a panchromatic spectrograph with supporting monochromatic imagers.

  8. Three Mars years: viking lander 1 imaging observations.

    PubMed

    Arvidson, R E; Guinness, E A; Moore, H J; Tillman, J; Wall, S D

    1983-11-01

    The Mutch Memorial Station (Viking Lander 1) on Mars acquired imaging and meteorological data over a period of 2245 martian days (3:3 martian years). This article discusses the deposition and erosion of thin deposits (ten to hundreds of micrometers) of bright red dust associated with global dust storms, and the removal of centimeter amounts of material in selected areas during a dust storm late in the third winter. Atmospheric pressure data acquired during the period of intense erosion imply that baroclinic disturbances and strong diurnal solar tidal heating combined to produce strong winds. Erosion occurred principally in areas where soil cohesion was reduced by earlier surface sampler activities. Except for redistribution of thin layers of materials, the surface appears to be remarkably stable, perhaps because of cohesion of the undisturbed surface material. PMID:17746178

  9. Some Important Observations Concerning Human Visual Image Coding

    NASA Astrophysics Data System (ADS)

    Overington, Ian

    1986-05-01

    During some 20 years of research into thresholds of visual performance we have required to explore deeply the developing knowledge in both physiology, neurophysiology and, to a lesser extent, anatomy of primate vision. Over the last few years, as interest in computer vision has grown, it has become clear to us that a number of aspects of image processing and coding by human vision are very simple yet powerful, but appear to have been largely overlooked or misrepresented in classical computer vision literature. The paper discusses some important aspects of early visual processing. It then endeavours to demonstrate some of the simple yet powerful coding procedures which we believe are or may be used by human vision and which may be applied directly to computer vision.

  10. Observing temperature fluctuations in humans using infrared imaging

    PubMed Central

    Liu, Wei-Min; Meyer, Joseph; Scully, Christopher G.; Elster, Eric; Gorbach, Alexander M.

    2013-01-01

    In this work we demonstrate that functional infrared imaging is capable of detecting low frequency temperature fluctuations in intact human skin and revealing spatial, temporal, spectral, and time-frequency based differences among three tissue classes: microvasculature, large sub-cutaneous veins, and the remaining surrounding tissue of the forearm. We found that large veins have stronger contractility in the range of 0.005-0.06 Hz compared to the other two tissue classes. Wavelet phase coherence and power spectrum correlation analysis show that microvasculature and skin areas without vessels visible by IR have high phase coherence in the lowest three frequency ranges (0.005-0.0095 Hz, 0.0095-0.02 Hz, and 0.02-0.06 Hz), whereas large veins oscillate independently. PMID:23538682

  11. Three mars years: Viking lander 1 imaging observations

    USGS Publications Warehouse

    Arvidson, R. E.; Guinness, E.A.; Moore, H.J.; Tillman, J.; Wall, S.D.

    1983-01-01

    The Mutch Memorial Station (Viking Lander 1) on Mars acquired imaging and meteorological data over a period of 2245 martian days (3:3 martian years). This article discusses the deposition and erosion of thin deposits (ten to hundreds of micrometers) of bright red dust associated with global dust storms, and the removal of centimeter amounts of material in selected areas during a dust storm late in the third winter. Atmospheric pressure data acquired during the period of intense erosion imply that baroclinic disturbances and strong diurnal solar tidal heating combined to produce strong winds. Erosion occurred principally in areas where soil cohesion was reduced by earlier surface sampler activities. Except for redistribution of thin layers of materials, the surface appears to be remarkably stable, perhaps because of cohesion of the undisturbed surface material.

  12. Radiometric Calibration of the Earth Observing System's Imaging Sensors

    NASA Technical Reports Server (NTRS)

    Slater, Philip N. (Principal Investigator)

    1997-01-01

    The work on the grant was mainly directed towards developing new, accurate, redundant methods for the in-flight, absolute radiometric calibration of satellite multispectral imaging systems and refining the accuracy of methods already in use. Initially the work was in preparation for the calibration of MODIS and HIRIS (before the development of that sensor was canceled), with the realization it would be applicable to most imaging multi- or hyper-spectral sensors provided their spatial or spectral resolutions were not too coarse. The work on the grant involved three different ground-based, in-flight calibration methods reflectance-based radiance-based and diffuse-to-global irradiance ratio used with the reflectance-based method. This continuing research had the dual advantage of: (1) developing several independent methods to create the redundancy that is essential for the identification and hopefully the elimination of systematic errors; and (2) refining the measurement techniques and algorithms that can be used not only for improving calibration accuracy but also for the reverse process of retrieving ground reflectances from calibrated remote-sensing data. The grant also provided the support necessary for us to embark on other projects such as the ratioing radiometer approach to on-board calibration (this has been further developed by SBRS as the 'solar diffuser stability monitor' and is incorporated into the most important on-board calibration system for MODIS)- another example of the work, which was a spin-off from the grant funding, was a study of solar diffuser materials. Journal citations, titles and abstracts of publications authored by faculty, staff, and students are also attached.

  13. Observation of moist convection in Jupiter's atmosphere. Galileo Imaging Team

    PubMed

    Gierasch; Ingersoll; Banfield; Ewald; Helfenstein; Simon-Miller; Vasavada; Breneman; Senske

    2000-02-10

    The energy source driving Jupiter's active meteorology is not understood. There are two main candidates: a poorly understood internal heat source and sunlight. Here we report observations of an active storm system possessing both lightning and condensation of water. The storm has a vertical extent of at least 50 km and a length of about 4,000 km. Previous observations of lightning on Jupiter have revealed both its frequency of occurrence and its spatial distribution, but they did not permit analysis of the detailed cloud structure and its dynamics. The present observations reveal the storm (on the day side of the planet) at the same location and within just a few hours of a lightning detection (on the night side). We estimate that the total vertical transport of heat by storms like the one observed here is of the same order as the planet's internal heat source. We therefore conclude that moist convection-similar to large clusters of thunderstorm cells on the Earth-is a dominant factor in converting heat flow into kinetic energy in the jovian atmosphere. PMID:10688191

  14. Improving Resolution and Depth of Astronomical Observations via Modern Mathematical Methods for Image Analysis

    NASA Astrophysics Data System (ADS)

    Castellano, M.; Ottaviani, D.; Fontana, A.; Merlin, E.; Pilo, S.; Falcone, M.

    2015-09-01

    In the past years modern mathematical methods for image analysis have led to a revolution in many fields, from computer vision to scientific imaging. However, some recently developed image processing techniques successfully exploited by other sectors have been rarely, if ever, experimented on astronomical observations. We present here tests of two classes of variational image enhancement techniques: "structure-texture decomposition" and "super-resolution" showing that they are effective in improving the quality of observations. Structure-texture decomposition allows to recover faint sources previously hidden by the background noise, effectively increasing the depth of available observations. Super-resolution yields an higher-resolution and a better sampled image out of a set of low resolution frames, thus mitigating problematics in data analysis arising from the difference in resolution/sampling between different instruments, as in the case of EUCLID VIS and NIR imagers.

  15. Highly varying daytime sodium airglow emissions over an equatorial station: a case study based on the measurements using a grating monochromator

    NASA Astrophysics Data System (ADS)

    Hossain, Md Mosarraf; Vineeth, Chandrashekheran Nair; Sumod, Sukumaran Nair Geetha Kumari; Pant, Tarun Kumar

    2014-12-01

    A case study is performed to investigate the probable reasons behind substantial daytime sodium (Na) D1 airglow intensity (589.6 nm) variations measured using a ground-based monochromator during the three near consecutive days of February 2007 from Trivandrum (8.5°N, 77°E), India. The roles of both the resonance fluorescence and the chemistry have been considered in this study. It appears that fluorescence plays only a minor role towards the observed five to nine times of large intensity variations among these days. From investigations on the role of chemistry, it seems that through the Chapman chemical scheme, Na abundance contribute favorably, while the O3 concentrations and the ambient temperature do not play any role as such for the observed intensity variations. From further investigations, it transpires that because of pressure differences (approximately 0.0002 to 0.0003 hPa/day) in the emitting altitude region among these days, the variations in collisional quenching of excited NaO*(A2Σ+) (first excited electronic state of NaO that produces D line) contribute considerably towards the observed intensity variations. From consideration of all the possible factors, it appears that whereas resonance fluorescence plays only a minor role, chemistry has contributed to greater extent towards the observed significant intensity differences among these days.

  16. Radiometric calibration of the Earth observing system's imaging sensors

    NASA Technical Reports Server (NTRS)

    Slater, P. N.

    1987-01-01

    Philosophy, requirements, and methods of calibration of multispectral space sensor systems as applicable to the Earth Observing System (EOS) are discussed. Vicarious methods for calibration of low spatial resolution systems, with respect to the Advanced Very High Resolution Radiometer (AVHRR), are then summarized. Finally, a theoretical introduction is given to a new vicarious method of calibration using the ratio of diffuse-to-global irradiance at the Earth's surfaces as the key input. This may provide an additional independent method for in-flight calibration.

  17. ALMA and the Future of Millimeter Imaging Observations

    NASA Astrophysics Data System (ADS)

    Wilner, David J.

    2016-01-01

    The Nearby Young Moving Groups sample the critical age when primordial disks around stars complete their transformation into planetary systems with associated debris. Millimeter wavelengths provide direct access to cool material in these circumstellar disks. The high angular resolution of interferometry at these long wavelengths enables resolved observations of solids in an optically thin regime, as well as the thermal, chemical, and dynamical structure of gas, if present. In this contribution, I briefly review the evolving landscape of millimeter telescopes, with emphasis on the revolutionary capabilities of the new international Atacama Large Millimeter/submillimeter Array (ALMA) and describe pertinent early science results.

  18. Data processing assessment for the Lunar Geoscience Observer imaging spectrometer

    NASA Technical Reports Server (NTRS)

    Irigoyen, R. E.; Liaw, H. M.

    1988-01-01

    On the Lunar Geoscience Observer project, a Visible and Infrared Mapping Spectrometer instrument has been proposed. This instrument will have science data input rates in the hundreds of kilobits per second (kbps) and an average telemetry output data rate of 4 kbps. Techniques that can be used to reduce the throughput of the instrument are editing, summing and averaging, data compression, data preprocessing, pattern recognition and snapshot data taking. Due to instrument limitations in the buffer memory size and processing speeds, a careful selection of the available techniques must be made.

  19. Imaging Analysis of Near-Field Recording Technique for Observation of Biological Specimens

    NASA Astrophysics Data System (ADS)

    Moriguchi, Chihiro; Ohta, Akihiro; Egami, Chikara; Kawata, Yoshimasa; Terakawa, Susumu; Tsuchimori, Masaaki; Watanabe, Osamu

    2006-07-01

    We present an analysis of the properties of an imaging based on a near-field recording technique in comparison with simulation results. In the system, the optical field distributions localized near the specimens are recorded as the surface topographic distributions of a photosensitive film. It is possible to observe both soft and moving specimens, because the system does not require a scanning probe to obtain the observed image. The imaging properties are evaluated using fine structures of paramecium, and we demonstrate that it is possible to observe minute differences of refractive indices.

  20. Generalization Evaluation of Machine Learning Numerical Observers for Image Quality Assessment.

    PubMed

    Kalayeh, Mahdi M; Marin, Thibault; Brankov, Jovan G

    2013-06-01

    In this paper, we present two new numerical observers (NO) based on machine learning for image quality assessment. The proposed NOs aim to predict human observer performance in a cardiac perfusion-defect detection task for single-photon emission computed tomography (SPECT) images. Human observer (HumO) studies are now considered to be the gold standard for task-based evaluation of medical images. However such studies are impractical for use in early stages of development for imaging devices and algorithms, because they require extensive involvement of trained human observers who must evaluate a large number of images. To address this problem, numerical observers (also called model observers) have been developed as a surrogate for human observers. The channelized Hotelling observer (CHO), with or without internal noise model, is currently the most widely used NO of this kind. In our previous work we argued that development of a NO model to predict human observers' performance can be viewed as a machine learning (or system identification) problem. This consideration led us to develop a channelized support vector machine (CSVM) observer, a kernel-based regression model that greatly outperformed the popular and widely used CHO. This was especially evident when the numerical observers were evaluated in terms of generalization performance. To evaluate generalization we used a typical situation for the practical use of a numerical observer: after optimizing the NO (which for a CHO might consist of adjusting the internal noise model) based upon a broad set of reconstructed images, we tested it on a broad (but different) set of images obtained by a different reconstruction method. In this manuscript we aim to evaluate two new regression models that achieve accuracy higher than the CHO and comparable to our earlier CSVM method, while dramatically reducing model complexity and computation time. The new models are defined in a Bayesian machine-learning framework: a channelized

  1. The advantages of using a Lucky Imaging camera for observations of microlensing events

    NASA Astrophysics Data System (ADS)

    Sajadian, Sedighe; Rahvar, Sohrab; Dominik, Martin; Hundertmark, Markus

    2016-05-01

    In this work, we study the advantages of using a Lucky Imaging camera for the observations of potential planetary microlensing events. Our aim is to reduce the blending effect and enhance exoplanet signals in binary lensing systems composed of an exoplanet and the corresponding parent star. We simulate planetary microlensing light curves based on present microlensing surveys and follow-up telescopes where one of them is equipped with a Lucky Imaging camera. This camera is used at the Danish 1.54-m follow-up telescope. Using a specific observational strategy, for an Earth-mass planet in the resonance regime, where the detection probability in crowded fields is smaller, Lucky Imaging observations improve the detection efficiency which reaches 2 per cent. Given the difficulty of detecting the signal of an Earth-mass planet in crowded-field imaging even in the resonance regime with conventional cameras, we show that Lucky Imaging can substantially improve the detection efficiency.

  2. Development of Fluorescence Imaging Lidar for Boat-Based Coral Observation

    NASA Astrophysics Data System (ADS)

    Sasano, Masahiko; Imasato, Motonobu; Yamano, Hiroya; Oguma, Hiroyuki

    2016-06-01

    A fluorescence imaging lidar system installed in a boat-towable buoy has been developed for the observation of reef-building corals. Long-range fluorescent images of the sea bed can be recorded in the daytime with this system. The viability of corals is clear in these fluorescent images because of the innate fluorescent proteins. In this study, the specifications and performance of the system are shown.

  3. Chemical contrast observed in thermal images of blood-stained fabrics exposed to steam.

    PubMed

    O'Brien, Wayne L; Boltin, Nicholas D; Lu, Zhenyu; Cassidy, Brianna M; Belliveau, Raymond G; Straub, Emory J; DeJong, Stephanie A; Morgan, Stephen L; Myrick, M L

    2015-09-21

    Thermal imaging is not ordinarily a good way to visualize chemical contrast. In recent work, however, we observed strong and reproducible images with chemical contrasts on blood-stained fabrics, especially on more hydrophobic fabrics like acrylic and polyester. PMID:26225800

  4. Asymptotic normality of kernel estimators for images observed under the radon transform in fan beam design

    NASA Astrophysics Data System (ADS)

    Proksch, Katharina

    2013-10-01

    We consider a nonparametric, two-dimensional regression model that describes observations of Radon transformed images, i.e., an inverse regression model. Reconstructions from deterministic fan beam design by a certain kind of kernel-type estimators are considered and their asymptotic properties are investigated. The problem discussed is related to medical imaging procedures such as computerized tomography (CT).

  5. Evaluation of the channelized Hotelling observer for signal detection in 2D tomographic imaging

    NASA Astrophysics Data System (ADS)

    LaRoque, Samuel J.; Sidky, Emil Y.; Edwards, Darrin C.; Pan, Xiaochuan

    2007-03-01

    Signal detection by the channelized Hotelling (ch-Hotelling) observer is studied for tomographic application by employing a small, tractable 2D model of a computed tomography (CT) system. The primary goal of this manuscript is to develop a practical method for evaluating the ch-Hotelling observer that can generalize to larger 3D cone-beam CT systems. The use of the ch-Hotelling observer for evaluating tomographic image reconstruction algorithms is also demonstrated. For a realistic model for CT, the ch-Hotelling observer can be a good approximation to the ideal observer. The ch-Hotelling observer is applied to both the projection data and the reconstructed images. The difference in signal-to-noise ratio for signal detection in both of these domains provides a metric for evaluating the image reconstruction algorithm.

  6. The need for hard X-ray imaging observations at the next solar maximum

    NASA Technical Reports Server (NTRS)

    Emslie, A. Gordon

    1988-01-01

    Canonical models of solar hard X-ray bursts; associated length and time scales; the adequacies and inadequacies of previous observations; theoretical modeling predictions; arcsecond imaging of solar hard X-rays are outlined.

  7. Numerical surrogates for human observers in myocardial motion evaluation from SPECT image

    PubMed Central

    Marin, Thibault; Kalayehis, Mahdi M.; Parages, Felipe M.; Brankov, Jovan G.

    2014-01-01

    In medical imaging, the gold standard for image-quality assessment is a task-based approach in which one evaluates human observer performance for a given diagnostic task (e.g., detection of a myocardial perfusion or motion defect). To facilitate practical task-based image-quality assessment, model observers are needed as approximate surrogates for human observers. In cardiac-gated SPECT imaging, diagnosis relies on evaluation of the myocardial motion as well as perfusion. Model observers for the perfusion-defect detection task have been studied previously, but little effort has been devoted toward development of a model observer for cardiac-motion defect detection. In this work describe two model observers for predicting human observer performance in detection of cardiac-motion defects. Both proposed methods rely on motion features extracted using previously reported deformable mesh model for myocardium motion estimation. The first method is based on a Hotelling linear discriminant that is similar in concept to that used commonly for perfusion-defect detection. In the second method, based on relevance vector machines (RVM) for regression, we compute average human observer performance by first directly predicting individual human observer scores, and then using multi reader receiver operating characteristic (ROC) analysis. Our results suggest that the proposed RVM model observer can predict human observer performance accurately, while the new Hotelling motion-defect detector is somewhat less effective. PMID:23981533

  8. Solar measurements from the Airglow-Solar Spectrometer Instrument (ASSI) on the San Marco 5 satellite

    NASA Technical Reports Server (NTRS)

    Woods, Thomas N.

    1994-01-01

    The analysis of the solar spectral irradiance from the Airglow-Solar Spectrometer Instrument (ASSI) on the San Marco 5 satellite is the focus for this research grant. A pre-print copy of the paper describing the calibrations of and results from the San Marco ASSI is attached to this report. The calibration of the ASSI included (1) transfer of photometric calibration from a rocket experiment and the Solar Mesosphere Explorer (SME), (2) use of the on-board radioactive calibration sources, (3) validation of the ASSI sensitivity over its field of view, and (4) determining the degradation of the spectrometers. We have determined that the absolute values for the solar irradiance needs adjustment in the current proxy models of the solar UV irradiance, and the amount of solar variability from the proxy models are in reasonable agreement with the ASSI measurements. This research grant also has supported the development of a new solar EUV irradiance proxy model. We expected that the magnetic flux is responsible for most of the heating, via Alfen waves, in the chromosphere, transition region, and corona. From examining time series of solar irradiance data and magnetic fields at different levels, we did indeed find that the chromospheric emissions correlate best with the large magnetic field levels.

  9. Solar measurements from the Airglow-Solar Spectrometer Instrument (ASSI) on the San Marco 5 satellite

    NASA Astrophysics Data System (ADS)

    Woods, Thomas N.

    1994-04-01

    The analysis of the solar spectral irradiance from the Airglow-Solar Spectrometer Instrument (ASSI) on the San Marco 5 satellite is the focus for this research grant. A pre-print copy of the paper describing the calibrations of and results from the San Marco ASSI is attached to this report. The calibration of the ASSI included (1) transfer of photometric calibration from a rocket experiment and the Solar Mesosphere Explorer (SME), (2) use of the on-board radioactive calibration sources, (3) validation of the ASSI sensitivity over its field of view, and (4) determining the degradation of the spectrometers. We have determined that the absolute values for the solar irradiance needs adjustment in the current proxy models of the solar UV irradiance, and the amount of solar variability from the proxy models are in reasonable agreement with the ASSI measurements. This research grant also has supported the development of a new solar EUV irradiance proxy model. We expected that the magnetic flux is responsible for most of the heating, via Alfen waves, in the chromosphere, transition region, and corona. From examining time series of solar irradiance data and magnetic fields at different levels, we did indeed find that the chromospheric emissions correlate best with the large magnetic field levels.

  10. Simultaneous measurements of the hydrogen airglow emissions of Lyman alpha, Lyman beta, and Balmer alpha.

    NASA Technical Reports Server (NTRS)

    Weller, C. S.; Meier, R. R.; Tinsley, B. A.

    1971-01-01

    Comparison of Lyman-alpha, 740- to 1050-A, and Balmer-alpha airglow measurements made at 134 deg solar-zenith angle on Oct. 13, 1969, with resonance-scattering models of solar radiation. Model comparison with Lyman-alpha data fixes the hydrogen column abundance over 215 km to 2 x 10 to the 13th per cu cm within a factor of 2. Differences between the Lyman-alpha model and data indicate a polar-equatorial departure from spherical symmetry in the hydrogen distribution. A Lyman-beta model based on the hydrogen distribution found to fit the Lyman-alpha data fits the spatial variation of the 740- to 1050-A data well from 100 to 130 km, but it does not fit the data well at higher altitudes; thus the presence of more rapidly absorbed shorter-wavelength radiation is indicated. This same resonance-scattering model yields Balmer-alpha intensities that result in good spatial agreement with the Balmer-alpha measurements, but a fivefold increase in the measured solar line center Lyman-beta flux is required (as required for the Lyman-beta measurement). The intensity ratio of Lyman-beta and Balmer-alpha at night is found to be a simple measure of the hydrogen optical depth if measurements with good accuracy can be made in the visible and ultraviolet spectrum.

  11. Model observer design for detecting multiple abnormalities in anatomical background images

    NASA Astrophysics Data System (ADS)

    Wen, Gezheng; Markey, Mia K.; Park, Subok

    2016-03-01

    As psychophysical studies are resource-intensive to conduct, model observers are commonly used to assess and optimize medical imaging quality. Existing model observers were typically designed to detect at most one signal. However, in clinical practice, there may be multiple abnormalities in a single image set (e.g., multifocal and multicentric breast cancers (MMBC)), which can impact treatment planning. Prevalence of signals can be different across anatomical regions, and human observers do not know the number or location of signals a priori. As new imaging techniques have the potential to improve multiple-signal detection (e.g., digital breast tomosynthesis may be more effective for diagnosis of MMBC than planar mammography), image quality assessment approaches addressing such tasks are needed. In this study, we present a model-observer mechanism to detect multiple signals in the same image dataset. To handle the high dimensionality of images, a novel implementation of partial least squares (PLS) was developed to estimate different sets of efficient channels directly from the images. Without any prior knowledge of the background or the signals, the PLS channels capture interactions between signals and the background which provide discriminant image information. Corresponding linear decision templates are employed to generate both image-level and location-specific scores on the presence of signals. Our preliminary results show that the model observer using PLS channels, compared to our first attempts with Laguerre-Gauss channels, can achieve high performance with a reasonably small number of channels, and the optimal design of the model observer may vary as the tasks of clinical interest change.

  12. I. Airglow on Mars: Model predictions for the oxygen IR atmospheric band at 1.27 micrometers, the hydroxyl radical Meinel bands and the hydroxyl radical A-X band system. II. Physical and chemical aeronomy of HD 209458b

    NASA Astrophysics Data System (ADS)

    Garcia Munoz, Antonio

    The first part of this dissertation is concerned with model predictions of airglow from the O2 IR atmospheric band at 1.27 mum, the OH Meinel bands and the OH A-X band system in the low-latitude neutral atmosphere of Mars. As an observable feature, airglow provides a means to remotely probe the composition, dynamics and energetics of the Martian atmosphere. The daytime emission from the O2 IR atmospheric band, a direct result of ozone photodissociation, has long been known to be a prominent emission of the Martian airglow. The motivation for pursuing the modelling of the nighttime components of the O2 IR atmospheric band and the OH Meinel bands is the potential of these two processes for characterizing the atomic oxygen profile in the 50-80 km region of the atmosphere. Likewise, the OH A-X band system may be useful to constrain the abundance of the hydroxyl radical on the illuminated side of the planet below 60 km. Both, O and OH are indicators of the photochemical state of the atmosphere. The results reported herein are expected to serve as guidelines for prospective observations of the atmosphere of Mars. The second part of the dissertation investigates the physical and chemical aeronomy of HD 209458b. The discovery of this extrasolar planet by radial velocity measurements was announced in 2000. Shortly afterwards, the inference of the mean planetary density from transit observations indicated the plausible gaseous nature of the planet. Later in-transit spectrally-resolved photometric observations revealed a cloud of hydrogen, carbon and oxygen atoms extending to a few planetary radii above the surface of the planet, which has been interpreted as evidence for an escaping atmosphere around HD 209458b. At an orbital distance of 0.05 AU, intense EUV stellar irradiation may lead to the massive escape of the atmosphere. In this work, the composition, escape and energy balance of the atmosphere are consistently modelled. Escape rates and abundances of the main hydrogen

  13. Metrics of medical image quality: task-based model observers vs. image discrimination/perceptual difference models

    NASA Astrophysics Data System (ADS)

    Eckstein, Miguel P.; Zhang, Yani; Pham, Binh T.

    2004-05-01

    There have been two distinct approaches to develop human vision models that can be used to perform automated evaluation and optimization of medical image quality: linear task based model observers vs. perceptual difference/image discrimination models. Although these two approaches are very different there has been little work directly comparing them in their ability to optimize human performance in clinically relevant tasks. We compared the effectiveness of these two types of metrics of image quality to perform automated computer optimization of JPEG 2000 image compression encoder settings using test images that combined real x-ray coronary angiogram backgrounds with simulated filling defects of 184 different size/shapes. A genetic algorithm was used to optimize the JPEG 2000 encoder settings with respect to: a) a particular task based model observer performance (non-prewhitening matched filter with an eye filter, NPWE; b) a particular perceptual difference/image discrimination model error metric (DCTune2.0; NASA Ames Research Center). A subsequent human psychophysical study was conducted to evaluate the effect of the two different optimized compression encoder settings on visual detection of the simulated filling defect in one of four locations (four alternative forced choice; 4 AFC). Results show that optimizing JPEG 2000 encoder settings with respect to both the NPWE performance and DCTune 2.0 perceptual error lead to improved human task performance relative to human performance with the default encoder settings. However, the NPWE-optimization led to much greater human performance improvement than the perceptual difference model optimization.

  14. STIS UV Imaging Spectroscopy of Io: First Results

    NASA Astrophysics Data System (ADS)

    Moos, H. W.; Retherford, K. D.; Feldman, P. D.; Strobel, D. F.; Roesler, F. L.; Hall, D. T.; McGrath, M. A.; Oliversen, R. J.

    1997-12-01

    The Space Telescope Imaging Spectrograph (STIS) obtained quasi-monochromatic images of far-UV emissions from Io's atmosphere and surrounding torus gas on September 26, 1997, when the satellite was near western elongation. The observations were acquired using the 52''{x}2'' STIS aperture centered on Io's 1.1'' diameter disk and aligned 43(deg) to the east of Jovian north. With the field of view of the detectors limiting the useful slit length to 25'', the G140M and G230M medium-dispersion STIS gratings produced isolated 25''{x}2'' images for different spectral lines. For sufficiently narrow lines the images show the spatial distribution of emissions in the dispersion direction as well as along the slit. High quality images of the OI]1355.6 Angstroms/1358.5 Angstroms and SI]1900.3 Angstroms/1914.7 Angstroms doublets were obtained along with a fainter image of the SI1388.7 Angstroms multiplet. Preliminary analysis shows a thin layer of emission outlining Io's limb with a localized brightening near Io's equatorial limbs. This airglow pattern is qualitatively consistent with recent visible-band images obtained by the Galileo spacecraft's Solid State Imager (Belton et al., Science 274, 5286 (1996)) and OI6300.3 Angstroms emission images by the Wide Field and Planetary Camera 2 (Trauger et al 1997).

  15. Spatio-temporal Hotelling observer for signal detection from image sequences

    PubMed Central

    Caucci, Luca; Barrett, Harrison H.; Rodríguez, Jeffrey J.

    2010-01-01

    Detection of signals in noisy images is necessary in many applications, including astronomy and medical imaging. The optimal linear observer for performing a detection task, called the Hotelling observer in the medical literature, can be regarded as a generalization of the familiar prewhitening matched filter. Performance on the detection task is limited by randomness in the image data, which stems from randomness in the object, randomness in the imaging system, and randomness in the detector outputs due to photon and readout noise, and the Hotelling observer accounts for all of these effects in an optimal way. If multiple temporal frames of images are acquired, the resulting data set is a spatio-temporal random process, and the Hotelling observer becomes a spatio-temporal linear operator. This paper discusses the theory of the spatio-temporal Hotelling observer and estimation of the required spatio-temporal covariance matrices. It also presents a parallel implementation of the observer on a cluster of Sony PLAYSTATION 3 gaming consoles. As an example, we consider the use of the spatio-temporal Hotelling observer for exoplanet detection. PMID:19550494

  16. Spatio-temporal Hotelling observer for signal detection from image sequences.

    PubMed

    Caucci, Luca; Barrett, Harrison H; Rodriguez, Jeffrey J

    2009-06-22

    Detection of signals in noisy images is necessary in many applications, including astronomy and medical imaging. The optimal linear observer for performing a detection task, called the Hotelling observer in the medical literature, can be regarded as a generalization of the familiar prewhitening matched filter. Performance on the detection task is limited by randomness in the image data, which stems from randomness in the object, randomness in the imaging system, and randomness in the detector outputs due to photon and readout noise, and the Hotelling observer accounts for all of these effects in an optimal way. If multiple temporal frames of images are acquired, the resulting data set is a spatio-temporal random process, and the Hotelling observer becomes a spatio-temporal linear operator. This paper discusses the theory of the spatio-temporal Hotelling observer and estimation of the required spatio-temporal covariance matrices. It also presents a parallel implementation of the observer on a cluster of Sony PLAYSTATION 3 gaming consoles. As an example, we consider the use of the spatio-temporal Hotelling observer for exoplanet detection. PMID:19550494

  17. High-Definition Television (HDTV) Images for Earth Observations and Earth Science Applications

    NASA Technical Reports Server (NTRS)

    Robinson, Julie A.; Holland, S. Douglas; Runco, Susan K.; Pitts, David E.; Whitehead, Victor S.; Andrefouet, Serge M.

    2000-01-01

    As part of Detailed Test Objective 700-17A, astronauts acquired Earth observation images from orbit using a high-definition television (HDTV) camcorder, Here we provide a summary of qualitative findings following completion of tests during missions STS (Space Transport System)-93 and STS-99. We compared HDTV imagery stills to images taken using payload bay video cameras, Hasselblad film camera, and electronic still camera. We also evaluated the potential for motion video observations of changes in sunlight and the use of multi-aspect viewing to image aerosols. Spatial resolution and color quality are far superior in HDTV images compared to National Television Systems Committee (NTSC) video images. Thus, HDTV provides the first viable option for video-based remote sensing observations of Earth from orbit. Although under ideal conditions, HDTV images have less spatial resolution than medium-format film cameras, such as the Hasselblad, under some conditions on orbit, the HDTV image acquired compared favorably with the Hasselblad. Of particular note was the quality of color reproduction in the HDTV images HDTV and electronic still camera (ESC) were not compared with matched fields of view, and so spatial resolution could not be compared for the two image types. However, the color reproduction of the HDTV stills was truer than colors in the ESC images. As HDTV becomes the operational video standard for Space Shuttle and Space Station, HDTV has great potential as a source of Earth-observation data. Planning for the conversion from NTSC to HDTV video standards should include planning for Earth data archiving and distribution.

  18. Experimental observation of sub-Rayleigh quantum imaging with a two-photon entangled source

    SciTech Connect

    Xu, De-Qin; Song, Xin-Bing; Li, Hong-Guo; Zhang, De-Jian; Wang, Hai-Bo; Xiong, Jun Wang, Kaige

    2015-04-27

    It has been theoretically predicted that N-photon quantum imaging can realize either an N-fold resolution improvement (Heisenberg-like scaling) or a √(N)-fold resolution improvement (standard quantum limit) beyond the Rayleigh diffraction bound, over classical imaging. Here, we report the experimental study on spatial sub-Rayleigh quantum imaging using a two-photon entangled source. Two experimental schemes are proposed and performed. In a Fraunhofer diffraction scheme with a lens, two-photon Airy disk pattern is observed with subwavelength diffraction property. In a lens imaging apparatus, however, two-photon sub-Rayleigh imaging for an object is realized with super-resolution property. The experimental results agree with the theoretical prediction in the two-photon quantum imaging regime.

  19. Technologies of diffractive imaging system for high-resolution earth observation from geostationary orbit

    NASA Astrophysics Data System (ADS)

    Chen, Xiaoli; Su, Yun; Jiao, Jianchao

    2013-08-01

    High-resolution earth observation from geostationary orbit (GEO) is a good way to satisfy the increased time resolution for resource, environment and disaster monitor. Earth observation from geostationary orbit will require optical remote sensor with ultra-large aperture. Given size, weight and launch ability constraints, as well as cost consideration, the traditional monolithic aperture optical system couldn't satisfy the need. This paper gives a new method, the diffractive imaging system. Diffract ive imaging system is a feasible way to realize high-resolution earth observation from geostationary orbit. The principle of diffract ive imaging system is introduced firstly, then, the primary design of remote sensor with 1m resolution from geostationary orbit using diffractive imaging system is analyzed. Finally, the key technologies are analyzed and feasible solutions are given.

  20. Observer assessment of multi-pinhole SPECT geometries for prostate cancer imaging: a simulation study

    NASA Astrophysics Data System (ADS)

    Kalantari, Faraz; Sen, Anando; Gifford, Howard C.

    2014-03-01

    SPECT imaging using In-111 ProstaScint is an FDA-approved method for diagnosing prostate cancer metastases within the pelvis. However, conventional medium-energy parallel-hole (MEPAR) collimators produce poor image quality and we are investigating the use of multipinhole (MPH) imaging as an alternative. This paper presents a method for evaluating MPH designs that makes use of sampling-sensitive (SS) mathematical model observers for tumor detectionlocalization tasks. Key to our approach is the redefinition of a normal (or background) reference image that is used with scanning model observers. We used this approach to compare different MPH configurations for the task of small-tumor detection in the prostate and surrounding lymph nodes. Four configurations used 10, 20, 30, and 60 pinholes evenly spaced over a complete circular orbit. A fixed-count acquisition protocol was assumed. Spherical tumors were placed within a digital anthropomorphic phantom having a realistic Prostascint biodistribution. Imaging data sets were generated with an analytical projector and reconstructed volumes were obtained with the OSEM algorithm. The MPH configurations were compared in a localization ROC (LROC) study with 2D pelvic images and both human and model observers. Regular and SS versions of the scanning channelized nonprewhitening (CNPW) and visual-search (VS) model observers were applied. The SS models demonstrated the highest correlations with the average human-observer results

  1. Research on Complicated Imaging Condition of GEO Optical High Resolution Earth Observing Satellite

    NASA Astrophysics Data System (ADS)

    Guo, Linghua

    2012-07-01

    The requirement for high time and space resolution of optical remote sensing satellite in disaster, land resources, environment, marine monitoring and meteorology observation, etc is getting urgent and strict. For that reason, a remote sensing satellite system solely located in MEO or LEO cannot operate continuous observation and Surveillance. GEO optical high resolution earth observing satellite in the other hand can keep the mesoscale and microscale target under continuous surveillance by controlling line of sight(LOS), and can provide imaging observation of an extensive region in a short time. The advantages of GEO satellite such as real-time observation of the mesoscale and microscale target, rapid response of key events, have been recognized by lots of countries and become a new trend of remote sensing satellite. As many advantages as the GEO remote sensing satellite has, its imaging condition is more complicated. Many new characteristics of imaging observation and imaging quality need to be discussed. We analyze each factor in the remote sensing link, using theoretical analysis and modeling simulation to get coefficient of each factor to represent its effect on imaging system. Such research achievements can provide reference for satellite mission analysis and system design.

  2. Objectively measuring signal detectability, contrast, blur and noise in medical images using channelized joint observers

    NASA Astrophysics Data System (ADS)

    Goossens, Bart; Luong, Hiêp; Platiša, Ljiljana; Philips, Wilfried

    2013-03-01

    To improve imaging systems and image processing techniques, objective image quality assessment is essential. Model observers adopting a task-based quality assessment strategy by estimating signal detectability measures, have shown to be quite successful to this end. At the same time, costly and time-consuming human observer experiments can be avoided. However, optimizing images in terms of signal detectability alone, still allows a lot of freedom in terms of the imaging parameters. More specifically, fixing the signal detectability defines a manifold in the imaging parameter space on which different "possible" solutions reside. In this article, we present measures that can be used to distinguish these possible solutions from each other, in terms of image quality factors such as signal blur, noise and signal contrast. Our approach is based on an extended channelized joint observer (CJO) that simultaneously estimates the signal amplitude, scale and detectability. As an application, we use this technique to design k-space trajectories for MRI acquisition. Our technique allows to compare the different spiral trajectories in terms of blur, noise and contrast, even when the signal detectability is estimated to be equal.

  3. Comparing Auroral Far Ultraviolet Images and Coincident Ionosonde Observations of the Auroral E Region

    NASA Astrophysics Data System (ADS)

    Knight, H. K., Jr.; Galkin, I. A.; Reinisch, B. W.

    2014-12-01

    Comparisons are being made between auroral ionospheric E region parameters derived from two types of observations: satellite-based far ultraviolet (FUV) imagers and ground-based ionosondes. The FUV imagers are: 1) NASA's Thermosphere Ionosphere Mesosphere Energetics and Dynamics Global Ultraviolet Imager (TIMED/GUVI) and 2) DMSP's Special Sensor Ultraviolet Spectrographic Imager (SSUSI). The ionosondes are five high latitude Digisondes included in the Global Ionospheric Radio Observatory (GIRO) (Reinisch and Galkin, EPS, 2011). The purpose of the comparisons is to determine whether auroral FUV remote sensing algorithms that derive E region parameters from Lyman-Birge-Hopfield (LBH) emissions are biased in the presence of proton aurora. Earlier comparisons between FUV images and in situ auroral particle flux observations (e.g., Knight et al., JGR, 2012) indicate that proton aurora is much more efficient than electron aurora in producing LBH emission, and to be consistent with these findings the FUV-ionosonde comparisons would have to show that auroral FUV-derived NmE (maximum E region electron density) is biased high in the presence of proton precipitation. The advantage of making comparisons with Digisonde observations of the E region (as opposed to incoherent scatter radar) is that Digisondes remain in operation continuously over extended periods of time (i.e. years) and record observations every few minutes, making it possible to gather large numbers of FUV image-coincident observations for statistical studies. The subject of how to interpret auroral E region traces in ionograms has not been studied much up to now, however, and we are making progress in that area. We have found that a modified version of the rules from Piggott and Rawer, U.R.S.I. Handbook of Ionogram Interpretation and Reduction(1972) gives a large number of usable ionograms and good correlation with auroral FUV observations. The figure shows an example of an auroral FUV image with the locations

  4. Image-domain sampling properties of the Hotelling Observer in CT using filtered back-projection

    NASA Astrophysics Data System (ADS)

    Sanchez, Adrian A.; Sidky, Emil Y.; Pan, Xiaochuan

    2015-03-01

    The Hotelling Observer (HO),1 along with its channelized variants,2 has been proposed for image quality evaluation in x-ray CT.3,4 In this work, we investigate HO performance for a detection task in parallel-beam FBP as a function of two image-domain sampling parameters, namely pixel size and field-of-view. These two parameters are of central importance in adapting HO methods to use in CT, since the large number of pixels in a single image makes direct computation of HO performance for a full image infeasible in most cases. Reduction of the number of image pixels and/or restriction of the image to a region-of-interest (ROI) has the potential to make direct computation of HO statistics feasible in CT, provided that the signal and noise properties lead to redundant information in some regions of the image. For small signals, we hypothesize that reduction of image pixel size and enlargement of the image field-of-view are approximately equivalent means of gaining additional information relevant to a detection task. The rationale for this hypothesis is that the backprojection operation in FBP introduces long range correlations so that, for small signals, the reconstructed signal outside of a small ROI is not linearly independent of the signal within the ROI. In this work, we perform a preliminary investigation of this hypothesis by sweeping these two sampling parameters and computing HO performance for a signal detection task.

  5. The study of enhanced earth observations on a satellite image chain

    NASA Astrophysics Data System (ADS)

    Yong, Sang-Soon; Choi, Myungjin; Ra, Sung-Woong

    2011-10-01

    The Multi-Spectral Camera (MSC) on the KOrea Multi-Propose SATellite (KOMPSAT)-2 was developed and launched as a main payload to provide a One(1) m panchromatic image and four(4) band four(4) m multi-spectral images at an altitude of 685 km covering a swath width of 15 km. These images, archived around the world, are a useful resource for space applications in agriculture, cartography, geology, forestry, regional planning, surveillance, and national security. The image quality of KOMPSAT-2 depends upon its image chain, which is comprised of an on-board system in the satellite and a processing system at the ground station. Therefore, in this study we determine the factors that have a major impact on the image quality through an investigation of the entire image chain. Consequently, two methods, involving a compression algorithm and a deconvolution technique, were determined as having a significant influence on the KOMPSAT-2 image quality. The compression algorithm of KOMPSAT-2 is rate-controlled JPEG-like algorithm that controls the mismatch between the input and output data rate. The ability to control the input/output data rate may be useful during the operation of the satellite but can also lower the overall image quality. The deconvolution technique may increase the sharpness of images, but it can also amplify the image noise level. Therefore, we propose methods of wavelet-based compression and denoising as an alternative to currently existing algorithms. Satisfactory results were obtained through experimentation with these two algorithms, and they are expected to be successfully implemented into the future KOMPSAT series to yield high-quality images for enhanced earth observation.

  6. Intriguing transmission electron microscopy images observed for perpendicularly oriented cylindrical microdomains of block copolymers

    NASA Astrophysics Data System (ADS)

    Ohnogi, Hiroshi; Isshiki, Toshiyuki; Sasaki, Sono; Sakurai, Shinichi

    2014-08-01

    Intriguing images of dislocation structures were observed by the transmission electron microscopy (TEM) technique for hexagonally packed cylindrical microdomains in a block copolymer (polystyrene-block-polyethylenebutylene-block-polystyrene triblock copolymer) film. The polystyrene (PS) cylinders were embedded in the polyethylenebutylene (PEB) matrix and oriented perpendicular to the surface of the thin section for the TEM observations. In order to understand such strange dislocation structures, we applied an image processing technique using two-dimensional Fourier transform (FT) and inverse Fourier transform (IFT) methods. It was found that these intriguing images were not ascribed to real dislocation structures but were fake ones due to the moiré effect caused by the overlapping of hexagons with a slightly mismatched orientation. Furthermore, grain boundaries in the ultrathin section can be identified by image processing using FT and IFT methods.Intriguing images of dislocation structures were observed by the transmission electron microscopy (TEM) technique for hexagonally packed cylindrical microdomains in a block copolymer (polystyrene-block-polyethylenebutylene-block-polystyrene triblock copolymer) film. The polystyrene (PS) cylinders were embedded in the polyethylenebutylene (PEB) matrix and oriented perpendicular to the surface of the thin section for the TEM observations. In order to understand such strange dislocation structures, we applied an image processing technique using two-dimensional Fourier transform (FT) and inverse Fourier transform (IFT) methods. It was found that these intriguing images were not ascribed to real dislocation structures but were fake ones due to the moiré effect caused by the overlapping of hexagons with a slightly mismatched orientation. Furthermore, grain boundaries in the ultrathin section can be identified by image processing using FT and IFT methods. Electronic supplementary information (ESI) available. See DOI: 10.1039/c

  7. Performance of PHOTONIS' low light level CMOS imaging sensor for long range observation

    NASA Astrophysics Data System (ADS)

    Bourree, Loig E.

    2014-05-01

    Identification of potential threats in low-light conditions through imaging is commonly achieved through closed-circuit television (CCTV) and surveillance cameras by combining the extended near infrared (NIR) response (800-10000nm wavelengths) of the imaging sensor with NIR LED or laser illuminators. Consequently, camera systems typically used for purposes of long-range observation often require high-power lasers in order to generate sufficient photons on targets to acquire detailed images at night. While these systems may adequately identify targets at long-range, the NIR illumination needed to achieve such functionality can easily be detected and therefore may not be suitable for covert applications. In order to reduce dependency on supplemental illumination in low-light conditions, the frame rate of the imaging sensors may be reduced to increase the photon integration time and thus improve the signal to noise ratio of the image. However, this may hinder the camera's ability to image moving objects with high fidelity. In order to address these particular drawbacks, PHOTONIS has developed a CMOS imaging sensor (CIS) with a pixel architecture and geometry designed specifically to overcome these issues in low-light level imaging. By combining this CIS with field programmable gate array (FPGA)-based image processing electronics, PHOTONIS has achieved low-read noise imaging with enhanced signal-to-noise ratio at quarter moon illumination, all at standard video frame rates. The performance of this CIS is discussed herein and compared to other commercially available CMOS and CCD for long-range observation applications.

  8. The potential of pigeons as surrogate observers in medical image perception studies

    NASA Astrophysics Data System (ADS)

    Krupinski, Elizabeth A.; Levenson, Richard M.; Navarro, Victor; Wasserman, Edward A.

    2016-03-01

    Assessment of medical image quality and how changes in image appearance impact performance are critical but assessment can be expensive and time-consuming. Could an animal (pigeon) observer with well-known visual skills and documented ability to distinguish complex visual stimuli serve as a surrogate for the human observer? Using sets of whole slide pathology (WSI) and mammographic images we trained pigeons (cohorts of 4) to detect and/or classify lesions in medical images. Standard training methods were used. A chamber equipped with a 15' display with a resistive touchscreen was used to display the images and record responses (pecks). Pigeon pellets were dispensed for correct responses. The pigeons readily learned to distinguish benign from malignant breast cancer histopathology in WSI (mean % correct responses rose 50% to 85% over 15 days) and generalized readily from 4X to 10X and 20X magnifications; to detect microcalcifications (mean % correct responses rose 50% to over 85% over 25 days); to distinguish benign from malignant breast masses (3 of 4 birds learned this task to around 80% and 60% over 10 days); and ignore compression artifacts in WSI (performance with uncompressed slides averaged 95% correct; 15:1 and 27:1 compression slides averaged 92% and 90% correct). Pigeons models may help us better understand medical image perception and may be useful in quality assessment by serving as surrogate observers for certain types of studies.

  9. Differential use of image enhancement techniques by experienced and inexperienced observers.

    PubMed

    Krupinski, Elizabeth A; Roehrig, Hans; Dallas, William; Fan, Jiahua

    2005-12-01

    Full-field digital mammography (FFDM) systems are currently being used to acquire mammograms in digital format, but digital displays are less than ideal compared to traditional film-screen display. Certain physical properties of softcopy displays [e.g., modulation transfer function (MTF)] are less than optimal compared to film. We developed methods to compensate for some of these softcopy display deficiencies, based on careful physical characterization of the displays and image-processing software. A series of 100 FFDM and 60 digitized images was shown to six observers-half experienced (mammographers) and half inexperienced (radiology residents). The observers had to decide if a mass or microcalcification cluster was present and classify it as benign or malignant. A window could be activated that brought the image detail within the window to full resolution and corrected for the nonisotropic MTF of the Cathode Ray Tube (CRT) display. Experienced readers had better diagnostic performance and took less time to view the images. Experienced readers used window/level more than inexperienced readers, but inexperienced readers used magnification and the MTF compensation tool more often. Use of the magnification and the MTF tool increased reader decision confidence. Experienced and inexperienced readers use image-processing tools differently, with certain tools increasing reader confidence. Understanding how observers use image-processing tools may help in the development of better and more automated user interfaces. PMID:16142436

  10. High-precision image aided inertial navigation with known features: observability analysis and performance evaluation.

    PubMed

    Jiang, Weiping; Wang, Li; Niu, Xiaoji; Zhang, Quan; Zhang, Hui; Tang, Min; Hu, Xiangyun

    2014-01-01

    A high-precision image-aided inertial navigation system (INS) is proposed as an alternative to the carrier-phase-based differential Global Navigation Satellite Systems (CDGNSSs) when satellite-based navigation systems are unavailable. In this paper, the image/INS integrated algorithm is modeled by a tightly-coupled iterative extended Kalman filter (IEKF). Tightly-coupled integration ensures that the integrated system is reliable, even if few known feature points (i.e., less than three) are observed in the images. A new global observability analysis of this tightly-coupled integration is presented to guarantee that the system is observable under the necessary conditions. The analysis conclusions were verified by simulations and field tests. The field tests also indicate that high-precision position (centimeter-level) and attitude (half-degree-level)-integrated solutions can be achieved in a global reference. PMID:25330046

  11. Lava flow surface textures - SIR-B radar image texture, field observations, and terrain measurements

    NASA Technical Reports Server (NTRS)

    Gaddis, Lisa R.; Mouginis-Mark, Peter J.; Hayashi, Joan N.

    1990-01-01

    SIR-B images, field observations, and small-scale (cm) terrain measurements are used to study lave flow surface textures related to emplacement processes of a single Hawaiian lava flow. Although smooth pahoehoe textures are poorly characterized on the SIR-B data, rougher pahoehoe types and the a'a flow portion show image textures attributed to spatial variations in surface roughness. Field observations of six distinct lava flow textural units are described and used to interpret modes of emplacement. The radar smooth/rough boundary between pahoehoe and a'a occurs at a vertical relief of about 10 cm on this lava flow. While direct observation and measurement most readily yield information related to lava eruption and emplacement processes, analyses of remote sensing data such as those acquired by imaging radars and altimeters can provide a means of quantifying surface texture, identifying the size and distribution of flow components, and delineating textural unit boundaries.

  12. High-Precision Image Aided Inertial Navigation with Known Features: Observability Analysis and Performance Evaluation

    PubMed Central

    Jiang, Weiping; Wang, Li; Niu, Xiaoji; Zhang, Quan; Zhang, Hui; Tang, Min; Hu, Xiangyun

    2014-01-01

    A high-precision image-aided inertial navigation system (INS) is proposed as an alternative to the carrier-phase-based differential Global Navigation Satellite Systems (CDGNSSs) when satellite-based navigation systems are unavailable. In this paper, the image/INS integrated algorithm is modeled by a tightly-coupled iterative extended Kalman filter (IEKF). Tightly-coupled integration ensures that the integrated system is reliable, even if few known feature points (i.e., less than three) are observed in the images. A new global observability analysis of this tightly-coupled integration is presented to guarantee that the system is observable under the necessary conditions. The analysis conclusions were verified by simulations and field tests. The field tests also indicate that high-precision position (centimeter-level) and attitude (half-degree-level)-integrated solutions can be achieved in a global reference. PMID:25330046

  13. Image observation of diffraction spots using FZP and coherent X-ray beam

    SciTech Connect

    Suzuki, Takuya; Yoshizuka, Kazuharu; Takano, Hidekazu; Takeuchi, Akihisa; Uesugi, Kentaro; Suzuki, Yoshio

    2004-05-12

    New small angle X-ray dispersion speckle method by the condensing optical system using FZP (Fresnel zone plate) was performed. And single crystal diffraction spot image was observed using this optical system. High photon flux with the FZP of 100-micron-diameter is obtained than that with a 5-micron-diameter pinhole. S/N ratio of data improved and measurement time also became short. The minimum beam size focused with the FZP was 0.25 {mu}m. The speckle image resulting from the non-ordering structure and periodic structure of 10nm order is successfully observed. This optical system was applicable also to diffraction spot image observation. We show a possibility that the information of the periodic and/or random structural analysis with sub-{mu}m order which were unsuitable with the conventional single crystal x-ray diffraction analysis.

  14. Observations of Io's Active Volcanoes from IRTF: Imaging and Occultation Lightcurves

    NASA Astrophysics Data System (ADS)

    Rathbun, J. A.; Spencer, J. R.

    2014-12-01

    We have been observing Ionian volcanism from NASA's Infrared Telescope Facility (IRTF) for more than two decades. The frequency of our observations increases dramatically when spacecraft are observing Io in order to complement the data returned by the spacecraft. The Japanese Space Agency's (JAXA) Hisaki (Sprint-A) mission recently observd the Jupiter system from earth orbit, monitoring the Io Plasma Torus and Jovian aurora. In order to investigate the possible influence of Io volcanism on the torus, we observed Io's volcanoes from the IRTF in Hawaii between September 2013 and May 2014. We imaged Io at 2.2, 3.5, and 4.8 microns in eclipse and reflected sunlight. We also observed Io during occultation by Jupiter, which allows us to locate and characterize individual volcanic eruptions, with greater spatial accuracy, on the Jupiter-facing hemisphere. The 2013 3.5 micron images of a sunlit Io showed no obvious bright volcanic features. However, further increases in spatial resolution is possible with shift-and-add processing of short exposure images. Preliminary occultation lightcurves from 2013 show moderate levels of activity at Kaneheliki/Janus and Loki, the two volcanic centers most often observed in occultation lightcurves. Loki was much brighter in 2013 than during the New Horizons flyby in 2007, but not as bright as during the Galileo era (see figure). From February 2014 through May 2014, due to a planned upgrade on the SPEX instrument and an unplanned required repair on the NSFCam2 instrument (both of which we have used previously), we exclusively used the CSHELL instrument as an imager. Unfortunately, CSHELL was not designed for imaging and has limited spatial resolution and photometric precision, complicating image analysis.

  15. Computational assessment of mammography accreditation phantom images and correlation with human observer analysis

    NASA Astrophysics Data System (ADS)

    Barufaldi, Bruno; Lau, Kristen C.; Schiabel, Homero; Maidment, D. A.

    2015-03-01

    Routine performance of basic test procedures and dose measurements are essential for assuring high quality of mammograms. International guidelines recommend that breast care providers ascertain that mammography systems produce a constant high quality image, using as low a radiation dose as is reasonably achievable. The main purpose of this research is to develop a framework to monitor radiation dose and image quality in a mixed breast screening and diagnostic imaging environment using an automated tracking system. This study presents a module of this framework, consisting of a computerized system to measure the image quality of the American College of Radiology mammography accreditation phantom. The methods developed combine correlation approaches, matched filters, and data mining techniques. These methods have been used to analyze radiological images of the accreditation phantom. The classification of structures of interest is based upon reports produced by four trained readers. As previously reported, human observers demonstrate great variation in their analysis due to the subjectivity of human visual inspection. The software tool was trained with three sets of 60 phantom images in order to generate decision trees using the software WEKA (Waikato Environment for Knowledge Analysis). When tested with 240 images during the classification step, the tool correctly classified 88%, 99%, and 98%, of fibers, speck groups and masses, respectively. The variation between the computer classification and human reading was comparable to the variation between human readers. This computerized system not only automates the quality control procedure in mammography, but also decreases the subjectivity in the expert evaluation of the phantom images.

  16. Combination of detection and estimation tasks using channelized scanning linear observer for CT imaging systems

    NASA Astrophysics Data System (ADS)

    Tseng, Hsin-Wu; Fan, Jiahua; Kupinski, Matthew A.

    2015-03-01

    Maintaining or even improving image quality while lowering patient dose is always the desire in clinical CT imaging. Iterative reconstruction (IR) algorithms have been designed to help reduce dose and/or provide better image quality. In this work, the channelized scanning linear observer (CSLO) is applied to study the combination of detection and estimation task performance using CT image data. The purpose of this work is to design a task-­-based approach to quantitatively evaluate image-­-quality for different reconstruction algorithms. Low-­-contrast objects embedded in head-­-size and body-­-size phantoms are imaged multiple times and reconstructed by FBP and an IR algorithm for this study. Independent signal present and absent ROIs cropped from images are channelized by Difference of Gauss channels for CSLO training and testing. Estimation receiver operating characteristic (EROC) curves and the area under EROC curve (EAUC) are calculated by CSLO as the figure of merit. The One-­- Shot method is used to compute the variance of the EAUC values. Results suggest that the IR algorithm studied in this work could efficiently reduce the dose approximately 54% to achieve an image quality comparable to conventional FBP reconstruction for the combined detection and estimation tasks.

  17. Spaceborne radar observations: A guide for Magellan radar-image analysis

    NASA Technical Reports Server (NTRS)

    Ford, J. P.; Blom, R. G.; Crisp, J. A.; Elachi, Charles; Farr, T. G.; Saunders, R. Stephen; Theilig, E. E.; Wall, S. D.; Yewell, S. B.

    1989-01-01

    Geologic analyses of spaceborne radar images of Earth are reviewed and summarized with respect to detecting, mapping, and interpreting impact craters, volcanic landforms, eolian and subsurface features, and tectonic landforms. Interpretations are illustrated mostly with Seasat synthetic aperture radar and shuttle-imaging-radar images. Analogies are drawn for the potential interpretation of radar images of Venus, with emphasis on the effects of variation in Magellan look angle with Venusian latitude. In each landform category, differences in feature perception and interpretive capability are related to variations in imaging geometry, spatial resolution, and wavelength of the imaging radar systems. Impact craters and other radially symmetrical features may show apparent bilateral symmetry parallel to the illumination vector at low look angles. The styles of eruption and the emplacement of major and minor volcanic constructs can be interpreted from morphological features observed in images. Radar responses that are governed by small-scale surface roughness may serve to distinguish flow types, but do not provide unambiguous information. Imaging of sand dunes is rigorously constrained by specific angular relations between the illumination vector and the orientation and angle of repose of the dune faces, but is independent of radar wavelength. With a single look angle, conditions that enable shallow subsurface imaging to occur do not provide the information necessary to determine whether the radar has recorded surface or subsurface features. The topographic linearity of many tectonic landforms is enhanced on images at regional and local scales, but the detection of structural detail is a strong function of illumination direction. Nontopographic tectonic lineaments may appear in response to contrasts in small-surface roughness or dielectric constant. The breakpoint for rough surfaces will vary by about 25 percent through the Magellan viewing geometries from low to high

  18. Observations of a Breakdown of a Mountain Wave Near 84 km Altitude Over Cerro Pachon Chile from the Andes Lidar Observatory

    NASA Astrophysics Data System (ADS)

    Hecht, J. H.; Gelinas, L. J.; Rudy, R. J.; Walterscheid, R. L.; Taylor, M. J.; Pautet, P. D.; Fritts, D. C.; Smith, S. M.; Franke, S. J.; Mlynczak, M. G.

    2015-12-01

    Mountain waves are produced by flow over orography. They propagate almost vertically, and are characterized by nearly zero velocity phase speed. The altitude to which they typically propagate is not well documented. They are thought to mainly dissipate by absorption in a critical layer although large-amplitude wave breakdown is also thought to occur. There have been almost no direct observations of the breakdown of mountain waves in the upper mesosphere and lower thermosphere. The region over Cerro Pachon Chile (a 2715 meter mountain in the Andes where large astronomical telescopes are located) is especially favorable to the production of mountain waves. In 2009 Smith and colleagues reported on the first observations of such waves propagating into the mesopause region (85 to 95 km) from El Leoncito Argentina, where waves over Cerro Pachon could be seen using airglow observations. The Aerospace Corporation's Nightglow Imager (ANI) is located at the Andes Lidar Observatory near the crest of Cerro Pachon. ANI observes nighttime OH emission (near 1.6 microns) every 2 seconds over an approximate 73 degree field of view. ANI had previously been used to the breakdown of Kelvin-Helmholtz instability features not associated with a specific gravity wave. Here we present OH airglow observations, originating near 84 km, from 22 UT to 3 UT on 8/9 July 2012 that show the breakdown of a mountain wave into instability features that subsequently dissipate into turbulence. These multi-hour observations provide the most detailed images to date of the breakdown of a mountain wave. The causes for, and the results of, the breakdown of this mountain wave are discussed.

  19. Magnetic resonance imaging findings in juvenile spondyloarthropathy and effects of treatment observed on subsequent imaging

    PubMed Central

    2014-01-01

    Background Magnetic resonance imaging (MRI) is often used to diagnose and monitor treatment effects of juvenile spondyloarthropathy (SpA). Our objective was to describe MRI findings in juvenile SpA and determine predictors of active sacroiliitis and response to treatment. Methods Children who had MRI of the sacroiliac (SI) joints and were referred to the pediatric rheumatology clinic from 2009 to 2012 were retrospectively studied. The clinical parameters, laboratory studies and findings on MRI were collected and a composite score ratio (CR) was calculated for both SI joints on each MRI study based on a semi-quantitative scale that included evaluation of bone marrow edema (BME), synovial enhancement (SE), and erosions (ER). The findings on MRI were correlated with clinical and laboratory values. Results 50 subjects who underwent 76 MRI for suspected or known SpA were included in the study. Sacroiliitis was seen in 48 MRIs in 32 subjects. Of the subjects with sacroiliitis, mean age ± standard deviation was 13.7 ± 2.6 years, 71% were male and 41% were HLA B27 positive. SE without BME was seen in 31% cases of sacroiliitis. In subjects with sacroiliitis, 79% also had hip arthritis and 41% had enthesitis of the pelvic region on MRI. In 38% of subjects with sacroiliitis, physical exam was not indicative of sacroiliitis or hip arthritis. Longitudinal data were available for 13 subjects. Sacroiliitis on MRI improved in 9 subjects with the greatest improvement in MRI composite score ratio after initiation of etanercept therapy. CR improvement was due to improvement of BME and SE components, while the ER score remained the same or worsened in all but 1 subject. Conclusion History, physical exam or laboratory data may not predict sacroiliitis in children. Magnetic resonance imaging plays a valuable role in the initial evaluation and later treatment monitoring of children with spondyloarthropathy. Synovial enhancement is significantly reduced after treatment, and

  20. Actual defect observation results of an extreme-ultraviolet blank mask by coherent diffraction imaging

    NASA Astrophysics Data System (ADS)

    Harada, Tetsuo; Hashimoto, Hiraku; Amano, Tsuyoshi; Kinoshita, Hiroo; Watanabe, Takeo

    2016-03-01

    Extreme-ultraviolet (EUV) lithography poses a number of challenges, one of which is the production of a defect-free mask. To observe the defects on an EUV mask in a quantitative phase image, we have developed a microcoherent EUV scatterometry microscope. The intensity and phase images of the defects are reconstructed using ptychography. We observe four actual defects on an EUV blank mask using the microscope. The reconstructed shapes of the actual defects correspond well to those measured by atomic force microscopy (AFM). Our microscope should therefore function as an essential review tool in characterizing defects.

  1. Analysis of plasmaspheric plumes: CLUSTER and IMAGE observations and numerical simulations

    NASA Technical Reports Server (NTRS)

    Darouzet, Fabien; DeKeyser, Johan; Decreau, Pierrette; Gallagher, Dennis; Pierrard, Viviane; Lemaire, Joseph; Dandouras, Iannis; Matsui, Hiroshi; Dunlop, Malcolm; Andre, Mats

    2005-01-01

    Plasmaspheric plumes have been routinely observed by CLUSTER and IMAGE. The CLUSTER mission provides high time resolution four-point measurements of the plasmasphere near perigee. Total electron density profiles can be derived from the plasma frequency and/or from the spacecraft potential (note that the electron spectrometer is usually not operating inside the plasmasphere); ion velocity is also measured onboard these satellites (but ion density is not reliable because of instrumental limitations). The EUV imager onboard the IMAGE spacecraft provides global images of the plasmasphere with a spatial resolution of 0.1 RE every 10 minutes; such images acquired near apogee from high above the pole show the geometry of plasmaspheric plumes, their evolution and motion. We present coordinated observations for 3 plume events and compare CLUSTER in-situ data (panel A) with global images of the plasmasphere obtained from IMAGE (panel B), and with numerical simulations for the formation of plumes based on a model that includes the interchange instability mechanism (panel C). In particular, we study the geometry and the orientation of plasmaspheric plumes by using a four-point analysis method, the spatial gradient. We also compare several aspects of their motion as determined by different methods: (i) inner and outer plume boundary velocity calculated from time delays of this boundary observed by the wave experiment WHISPER on the four spacecraft, (ii) ion velocity derived from the ion spectrometer CIS onboard CLUSTER, (iii) drift velocity measured by the electron drift instrument ED1 onboard CLUSTER and (iv) global velocity determined from successive EUV images. These different techniques consistently indicate that plasmaspheric plumes rotate around the Earth, with their foot fully co-rotating, but with their tip rotating slower and moving farther out.

  2. Ionospheric Studies From Low to Sub-Auroral Latitudes Using Geomagnetic Conjugate All-Sky Imagers and Satellite Data

    NASA Astrophysics Data System (ADS)

    Martinis, C. R.; Macinnis, R.; Sullivan, C.; Baumgardner, J. L.; Pfaff, R. F., Jr.; Hairston, M. R.; Mendillo, M.; Taylor, M. J.; Moffat-Griffin, T.; Heelis, R. A.; Wroten, J.; Hickey, D.

    2014-12-01

    Magnetically conjugate all-sky imagers (ASIs) from low to sub-auroral latitudes are used to investigate inter-hemispheric coupling of ionospheric processes including medium scale travelling ionospheric disturbances (MSTIDs) and, at higher latitudes, stable auroral red (SAR) arcs. The chain of imagers operated by Boston University in the American sector provide thermosphere/ionosphere information through the observation of brightness patterns in 630.0 nm airglow simultaneously at both hemispheres. Complementary information was obtained from space-based satellite data (C/NOFS, DMSP, GPS and RBSP). This study aims to present a comprehensive analysis of thermosphere/ionosphere processes and their coupling mechanisms covering L-shell values from ~ 1.1 to ~3.

  3. A Survey of All-sky Imaging Measurements of Bore- and "Wall"-like Disturbances in Mesospheric Nightglow.

    NASA Astrophysics Data System (ADS)

    Smith, S. M.

    2004-05-01

    All-sky imagers regularly record quasi-monochromatic (QM) gravity wave activity in the various night-time mesospheric emissions (Taylor et al., 1995; Wu and Killeen, 1996; Swenson et al., 1999; Smith et al., 2000, for example). There is, however, a distinct class of uncommon events - sudden and very bright all-sky airglow emission enhancements or depletions followed by a series of propagating waves that are phase-locked to the leading front and lasting several hours. Very few cases have been reported in the literature and they appear to consist of two distinct types of disturbances: "wall" events and bores. This paper will present and discuss observations of these two types of wave events recorded by the Boston University all-sky imagers at four separate locations: Millstone Hill (MA), Arecibo Observatory (PR), McDonald Observatory (TX), and El Leoncito (Argentina). A comparison of these events with those reported in the literature will also be made.

  4. Monte Carlo Radiative Transfer Modeling of Lightning Observed in Galileo Images of Jupiter

    NASA Technical Reports Server (NTRS)

    Dyudine, U. A.; Ingersoll, Andrew P.

    2002-01-01

    We study lightning on Jupiter and the clouds illuminated by the lightning using images taken by the Galileo orbiter. The Galileo images have a resolution of 25 km/pixel and axe able to resolve the shape of the single lightning spots in the images, which have full widths at half the maximum intensity in the range of 90-160 km. We compare the measured lightning flash images with simulated images produced by our ED Monte Carlo light-scattering model. The model calculates Monte Carlo scattering of photons in a ED opacity distribution. During each scattering event, light is partially absorbed. The new direction of the photon after scattering is chosen according to a Henyey-Greenstein phase function. An image from each direction is produced by accumulating photons emerging from the cloud in a small range (bins) of emission angles. Lightning bolts are modeled either as points or vertical lines. Our results suggest that some of the observed scattering patterns axe produced in a 3-D cloud rather than in a plane-parallel cloud layer. Lightning is estimated to occur at least as deep as the bottom of the expected water cloud. For the six cases studied, we find that the clouds above the lightning are optically thick (tau > 5). Jovian flashes are more regular and circular than the largest terrestrial flashes observed from space. On Jupiter there is nothing equivalent to the 30-40-km horizontal flashes which axe seen on Earth.

  5. Observation of sea-ice dynamics using synthetic aperture radar images: Automated analysis

    NASA Technical Reports Server (NTRS)

    Vesecky, John F.; Samadani, Ramin; Smith, Martha P.; Daida, Jason M.; Bracewell, Ronald N.

    1988-01-01

    The European Space Agency's ERS-1 satellite, as well as others planned to follow, is expected to carry synthetic-aperture radars (SARs) over the polar regions beginning in 1989. A key component in utilization of these SAR data is an automated scheme for extracting the sea-ice velocity field from a time sequence of SAR images of the same geographical region. Two techniques for automated sea-ice tracking, image pyramid area correlation (hierarchical correlation) and feature tracking, are described. Each technique is applied to a pair of Seasat SAR sea-ice images. The results compare well with each other and with manually tracked estimates of the ice velocity. The advantages and disadvantages of these automated methods are pointed out. Using these ice velocity field estimates it is possible to construct one sea-ice image from the other member of the pair. Comparing the reconstructed image with the observed image, errors in the estimated velocity field can be recognized and a useful probable error display created automatically to accompany ice velocity estimates. It is suggested that this error display may be useful in segmenting the sea ice observed into regions that move as rigid plates of significant ice velocity shear and distortion.

  6. PATHOLOGIC BASIS FOR RIM ENHANCEMENT OBSERVED IN COMPUTED TOMOGRAPHIC IMAGES OF FELINE NASOPHARYNGEAL POLYPS.

    PubMed

    Lamb, Christopher R; Sibbing, Kendall; Priestnall, Simon L

    2016-03-01

    In postcontrast computed tomographic (CT) images, feline nasopharyngeal polyps typically demonstrate enhancement of the peripheral rim. Computed tomographic images and histologic specimens of a case series of 22 cats with surgically removed nasopharyngeal polyps were reviewed retrospectively in an attempt to elucidate the origin of rim enhancement. Polyps were present in the tympanic cavity in 15 (68%) cats (three with extension into the nasopharynx), only in the nasopharynx in four (18%) cats, and only in the external ear canal in the remaining three (14%) cats. All polyps had variable degrees of epithelial injury. Hemorrhage and inflammatory infiltration were significantly more marked in the superficial stroma whereas edema was significantly more marked in the core stroma. In noncontrast CT images (n = 22), the tympanic bulla was thickened in all 15 cats with a polyp in the tympanic cavity and enlarged in eight (53%) of these cats. In postcontrast CT images (n = 15), an outer zone of relatively increased attenuation compatible with a rim was observed in 11 (73%) polyps. The magnitude and extent of rim enhancement in CT images was positively correlated with the histologic grade of inflammation in the superficial stroma and negatively correlated with the grade of edema in the superficial stroma. It appears that inflammation is the major determinant of contrast medium accumulation in feline nasopharyngeal polyps, and the tendency for inflammation to affect predominantly the superficial layers explains the frequent observation of a rim in postcontrast CT images. PMID:26763944

  7. Pigeons (Columba livia) as Trainable Observers of Pathology and Radiology Breast Cancer Images

    PubMed Central

    Levenson, Richard M.; Krupinski, Elizabeth A.; Navarro, Victor M.; Wasserman, Edward A.

    2015-01-01

    Pathologists and radiologists spend years acquiring and refining their medically essential visual skills, so it is of considerable interest to understand how this process actually unfolds and what image features and properties are critical for accurate diagnostic performance. Key insights into human behavioral tasks can often be obtained by using appropriate animal models. We report here that pigeons (Columba livia)—which share many visual system properties with humans—can serve as promising surrogate observers of medical images, a capability not previously documented. The birds proved to have a remarkable ability to distinguish benign from malignant human breast histopathology after training with differential food reinforcement; even more importantly, the pigeons were able to generalize what they had learned when confronted with novel image sets. The birds’ histological accuracy, like that of humans, was modestly affected by the presence or absence of color as well as by degrees of image compression, but these impacts could be ameliorated with further training. Turning to radiology, the birds proved to be similarly capable of detecting cancer-relevant microcalcifications on mammogram images. However, when given a different (and for humans quite difficult) task—namely, classification of suspicious mammographic densities (masses)—the pigeons proved to be capable only of image memorization and were unable to successfully generalize when shown novel examples. The birds’ successes and difficulties suggest that pigeons are well-suited to help us better understand human medical image perception, and may also prove useful in performance assessment and development of medical imaging hardware, image processing, and image analysis tools. PMID:26581091

  8. Pigeons (Columba livia) as Trainable Observers of Pathology and Radiology Breast Cancer Images.

    PubMed

    Levenson, Richard M; Krupinski, Elizabeth A; Navarro, Victor M; Wasserman, Edward A

    2015-01-01

    Pathologists and radiologists spend years acquiring and refining their medically essential visual skills, so it is of considerable interest to understand how this process actually unfolds and what image features and properties are critical for accurate diagnostic performance. Key insights into human behavioral tasks can often be obtained by using appropriate animal models. We report here that pigeons (Columba livia)-which share many visual system properties with humans-can serve as promising surrogate observers of medical images, a capability not previously documented. The birds proved to have a remarkable ability to distinguish benign from malignant human breast histopathology after training with differential food reinforcement; even more importantly, the pigeons were able to generalize what they had learned when confronted with novel image sets. The birds' histological accuracy, like that of humans, was modestly affected by the presence or absence of color as well as by degrees of image compression, but these impacts could be ameliorated with further training. Turning to radiology, the birds proved to be similarly capable of detecting cancer-relevant microcalcifications on mammogram images. However, when given a different (and for humans quite difficult) task-namely, classification of suspicious mammographic densities (masses)-the pigeons proved to be capable only of image memorization and were unable to successfully generalize when shown novel examples. The birds' successes and difficulties suggest that pigeons are well-suited to help us better understand human medical image perception, and may also prove useful in performance assessment and development of medical imaging hardware, image processing, and image analysis tools. PMID:26581091

  9. Image enhancement filters significantly improve reading performance for low vision observers

    NASA Technical Reports Server (NTRS)

    Lawton, T. B.

    1992-01-01

    As people age, so do their photoreceptors; many photoreceptors in central vision stop functioning when a person reaches their late sixties or early seventies. Low vision observers with losses in central vision, those with age-related maculopathies, were studied. Low vision observers no longer see high spatial frequencies, being unable to resolve fine edge detail. We developed image enhancement filters to compensate for the low vision observer's losses in contrast sensitivity to intermediate and high spatial frequencies. The filters work by boosting the amplitude of the less visible intermediate spatial frequencies. The lower spatial frequencies. These image enhancement filters not only reduce the magnification needed for reading by up to 70 percent, but they also increase the observer's reading speed by 2-4 times. A summary of this research is presented.

  10. A stereo matching model observer for stereoscopic viewing of 3D medical images

    NASA Astrophysics Data System (ADS)

    Wen, Gezheng; Markey, Mia K.; Muralidlhar, Gautam S.

    2014-03-01

    Stereoscopic viewing of 3D medical imaging data has the potential to increase the detection of abnormalities. We present a new stereo model observer inspired by the characteristics of stereopsis in human vision. Given a stereo pair of images of an object (i.e., left and right images separated by a small displacement), the model observer rst nds the corresponding points between the two views, and then fuses them together to create a 2D cyclopean view. Assuming that the cyclopean view has extracted most of the 3D information presented in the stereo pair, a channelized Hotelling observer (CHO) can be utilized to make decisions. We conduct a simulation study that attempts to mimic the detection of breast lesions on stereoscopic viewing of breast tomosynthesis projection images. We render voxel datasets that contain random 3D power-law noise to model normal breast tissues with various breast densities. 3D Gaussian signal is added to some of the datasets to model the presence of a breast lesion. By changing the separation angle between the two views, multiple stereo pairs of projection images are generated for each voxel dataset. The performance of the model is evaluated in terms of the accuracy of binary decisions on the presence of the simulated lesions.

  11. Inter- and Intra-Observer Variability in Prostate Definition With Tissue Harmonic and Brightness Mode Imaging

    SciTech Connect

    Sandhu, Gurpreet Kaur; Dunscombe, Peter; Meyer, Tyler; Pavamani, Simon; Khan, Rao

    2012-01-01

    Purpose: The objective of this study was to compare the relative utility of tissue harmonic (H) and brightness (B) transrectal ultrasound (TRUS) images of the prostate by studying interobserver and intraobserver variation in prostate delineation. Methods and Materials: Ten patients with early-stage disease were randomly selected. TRUS images of prostates were acquired using B and H modes. The prostates on all images were contoured by an experienced radiation oncologist (RO) and five equally trained observers. The observers were blinded to information regarding patient and imaging mode. The volumes of prostate glands and areas of midgland slices were calculated. Volumes contoured were compared among the observers and between observer group and RO. Contours on one patient were repeated five times by four observers to evaluate the intraobserver variability. Results: A one-sample Student t-test showed the volumes outlined by five observers are in agreement (p > 0.05) with the RO. Paired Student t-test showed prostate volumes (p = 0.008) and midgland areas (p = 0.006) with H mode were significantly smaller than that with B mode. Two-factor analysis of variances showed significant interobserver variability (p < 0.001) in prostate volumes and areas. Inter- and intraobserver consistency was quantified as the standard deviation of mean volumes and areas, and concordance indices. It was found that for small glands ({<=}35 cc) H mode provided greater interobserver consistency; however, for large glands ({>=}35 cc), B mode provided more consistent estimates. Conclusions: H mode provided superior inter- and intraobserver agreement in prostate volume definition for small to medium prostates. In large glands, H mode does not exhibit any additional advantage. Although harmonic imaging has not proven advantageous for all cases, its utilization seems to be judicious for small prostates.

  12. The SWAP EUV imager onboard PROBA2: 3 years of observations

    NASA Astrophysics Data System (ADS)

    West, Matthew; Berghmans, David; Seaton, Daniel

    The Sun Watcher with Active Pixels and Image Processing (SWAP) imager is an EUV solar telescope on board ESA's Project for Onboard Autonomy 2 (PROBA2) mission launched on 2 November 2009. SWAP has a spectral bandpass centered on 17.4 nm and provides images of the low solar corona over a 54x54 arcmin field-of-view with 3.2 arcsec pixels and an imaging cadence of about two minutes. SWAP is designed to monitor all space-weather-relevant events and features in the low solar corona. The SWAP telescope is designed with various innovative technologies, including an off-axis optical design and a CMOS-APS detector. I will present what has been learnt from 3 years of SWAP operations, the advantages of the CMOS detector and SWAPs setup, and a few unique PROBA2/SWAP observations.

  13. The Sheath Transport Observer for the Redistribution of Mass (STORM) Imager

    NASA Technical Reports Server (NTRS)

    Collier, Michael R.; Sibeck, David G.; Porter, F. Scott; Burch, J.; Carter, J. A.; Cravens, Thomas; Kuntz, Kip; Omidi, N.; Read, A.; Robertson, Ina; Sembay, S.; Snowden, Steven L.

    2010-01-01

    All of the solar wind energy that powers magnetospheric processes passes through the magnetosheath and magnetopause. Global images of the magnetosheath and magnetopause boundary layers will resolve longstanding controversies surrounding fundamental phenomena that occur at the magnetopause and provide information needed to improve operational space weather models. Recent developments showing that soft X-rays (0.15-1 keV) result from high charge state solar wind ions undergoing charge exchange recombination through collisions with exospheric neutral atoms has led to the realization that soft X-ray imaging can provide global maps of the high-density shocked solar wind within the magnetosheath and cusps, regions lying between the lower density solar wind and magnetosphere. We discuss an instrument concept called the Sheath Transport Observer for the Redistribution of Mass (STORM), an X-ray imager suitable for simultaneously imaging the dayside magnetosheath, the magnetopause boundary layers, and the cusps.

  14. The Sheath Transport Observer for the Redistribution of Mass (STORM) Image

    NASA Technical Reports Server (NTRS)

    Kuntz, Kip; Collier, Michael; Sibeck, David G.; Porter, F. Scott; Carter, J. A.; Cravens, Thomas; Omidi, N.; Robertson, Ina; Sembay, S.; Snowden, Steven L.

    2008-01-01

    All of the solar wind energy that powers magnetospheric processes passes through the magnetosheath and magnetopause. Global images of the magnetosheath and magnetopause boundary layers will resolve longstanding controversy surrounding fundamental phenomena that occur at the magnetopause and provide information needed to improve operational space weather models. Recent developments showing that soft X-rays (0.15-1 keV) result from high charge state solar wind ions undergoing charge exchange recombination through collisions with exospheric neutral atoms has led to the realization that soft X-ray imaging can provide global maps of the high-density shocked solar wind within the magnetosheath and cusps, regions lying between the lower density solar wind and magnetosphere. We discuss an instrument concept called the Sheath Transport Observer for the Redistribution of Mass (STORM), an X-ray imager suitable for simultaneously imaging the dayside magnetosheath, the magnetopause boundary layers, and the cusps.

  15. EIT: Solar corona synoptic observations from SOHO with an Extreme-ultraviolet Imaging Telescope

    NASA Technical Reports Server (NTRS)

    Delaboudiniere, J. P.; Gabriel, A. H.; Artzner, G. E.; Michels, D. J.; Dere, K. P.; Howard, R. A.; Catura, R.; Stern, R.; Lemen, J.; Neupert, W.

    1988-01-01

    The Extreme-ultraviolet Imaging Telescope (EIT) of SOHO (solar and heliospheric observatory) will provide full disk images in emission lines formed at temperatures that map solar structures ranging from the chromospheric network to the hot magnetically confined plasma in the corona. Images in four narrow bandpasses will be obtained using normal incidence multilayered optics deposited on quadrants of a Ritchey-Chretien telescope. The EIT is capable of providing a uniform one arc second resolution over its entire 50 by 50 arc min field of view. Data from the EIT will be extremely valuable for identifying and interpreting the spatial and temperature fine structures of the solar atmosphere. Temporal analysis will provide information on the stability of these structures and identify dynamical processes. EIT images, issued daily, will provide the global corona context for aid in unifying the investigations and in forming the observing plans for SOHO coronal instruments.

  16. Moderate resolution imaging spectroradiometer (MODIS) and observations of the land surface

    NASA Technical Reports Server (NTRS)

    Salomonson, V. V.; Toll, D. L.; Lawrence, W. T.

    1992-01-01

    The moderate resolution imaging spectroradiometer (MODIS) is a NASA facility instrument that is being designed for flight on the Earth Observing System (EOS) series of missions. It is designed to measure biophysical states and dynamics of the land, atmosphere, and ocean. Plans are required for use of other instruments that will be accompanying MODIS on the EOS missions, such as the High-Resolution Imaging Spectrometer (HIRIS) and the Multi-angle Imaging Spectro-Radiometer (MISR). The HIRIS instrument, a spectrometer operating in the visible to shortwave infrared parts of the spectrum, would be employed in combination with the MODIS to understand the impact of sampling the spectrum and the effects of land cover mixtures within the MODIS pixel. The MISR will help in understanding the effects of anisotropy in reflected solar radiation. Both instruments will work in combination with MODIS to better quantify the effects of the atmosphere on observations of surface properties.

  17. Performance comparison of breast imaging modalities using a 4AFC human observer study

    NASA Astrophysics Data System (ADS)

    Elangovan, Premkumar; Rashidnasab, Alaleh; Mackenzie, Alistair; Dance, David R.; Young, Kenneth C.; Bosmans, Hilde; Segars, William P.; Wells, Kevin

    2015-03-01

    This work compares the visibility of spheres and simulated masses in 2D-mammography and tomosynthesis systems using human observer studies. Performing comparison studies between breast imaging systems poses a number of practical challenges within a clinical environment. We therefore adopted a simulation approach which included synthetic breast blocks, a validated lesion simulation model and a set of validated image modelling tools as a viable alternative to clinical trials. A series of 4-alternative forced choice (4AFC) human observer experiments has been conducted for signal detection tasks using masses and spheres as targets. Five physicists participated in the study viewing images with a 5mm target at a range of contrast levels and 60 trials per experimental condition. The results showed that tomosynthesis has a lower threshold contrast than 2D-mammography for masses and spheres, and that detection studies using spheres may produce overly-optimistic threshold contrast values.

  18. Hyperspectral imaging Fourier transform spectrometers for astronomical and remote sensing observations

    NASA Astrophysics Data System (ADS)

    Rafert, J. Bruce; Sellar, R. Glenn; Holbert, Eirik; Blatt, Joel H.; Tyler, David W.; Durham, Susan E.; Newby, Harold D.

    1994-06-01

    The Florida Institue of Technology and the Phillips Laboratory have developed several advanced visible (0.4-0.8 micrometers ) imaging fourier transform spectrometer (IFTS) brassboards, which simultaneously acquire one spatial and one spectral dimension of the hyperspectral image cube. The initial versions of these instruments may be scanned across a scene or configured with a scan mirror to pick up the second spatial dimension of the image cube. The current visible hyperspectral imagers possess a combination of features, including (1) low to moderate spectral resolution for hundreds/thousands of spectral channels, (2) robust design, with no moving parts, (3) detector limited free spectral range, (4) detector-limited spatial and spectral resolution, and (5) field widened operation. The utility of this type of instrument reaches its logical conclusion however, with an instrument designed to acquire all three dimensions of the hyperspectral image cube (both spatial and one spectral) simultaneously. In this paper we present the (1) detailed optical system designs for the brassboard instruments, (2) the current data acquisition system, (3) data reduction and analysis techniques unique to hyperspectral sensor systems which operate with photometric accuracy, and (4) several methods to modify the basic instrument design to allow simultaneous acquistion of the entire hyperspectral image cube. The hyperspectral sensor systems which are being developed and whose utility is being pioneered by Florida Tech and the Phillips Laboratory are applicable to numerous DoD and civil applications including (1) space object identification, (2) radiometrically correct satellite image and spectral signature database observations, (3) simultaneous spactial/spectral observations of booster plumes for strategic and surrogate tactical missile signature identification, and (4) spatial/spectral visible and IR astronomical observations with photometric accuracy.

  19. Wide-field direct CCD observations supporting the Astro-1 Space Shuttle mission's Ultraviolet Imaging Telescope

    NASA Technical Reports Server (NTRS)

    Hintzen, Paul; Angione, Ron; Talbert, Freddie; Cheng, K.-P.; Smith, Eric; Stecher, Theodore P.

    1993-01-01

    Wide field direct CCD observations are being obtained to support and complement the vacuum-ultraviolet (VUV) images provided by Astro's Ultraviolet Imaging Telescope (UIT) during a Space Shuttle flight in December 1990. Because of the wide variety of projects addressed by UIT, the fields observed include (1) galactic supernova remnants such as the Cygnus Loop and globular clusters such as Omega Cen and M79; (2) the Magellanic Clouds, M33, M81, and other galaxies in the Local Group; and (3) rich clusters of galaxies, principally the Perseus cluster and Abell 1367. Ground-based observations have been obtained for virtually all of the Astro-1 UIT fields. The optical images allow identification of individual UV sources in each field and provide the long baseline in wavelength necessary for accurate analysis of UV-bright sources. To facilitate use of our optical images for analysis of UIT data and other projects, we plan to archive them, with the UIT images, at the National Space Science Data Center (NSSDC), where they will be universally accessible via anonymous FTP. The UIT, one of three telescopes comprising the Astro spacecraft, is a 38-cm f/9 Ritchey-Chretien telescope on which high quantum efficiency, solar-blind image tubes are used to record VUV images on photographic film. Five filters with passbands centered between 1250A and 2500A provide both VUV colors and a measurement of extinction via the 2200A dust feature. The resulting calibrated VUV pictures are 40 arcminutes in diameter at 2.5 arcseconds resolution. The capabilities of UIT, therefore, complement HST's WFPC: the latter has 40 times greater collecting area, while UIT's usable field has 170 times WFPC's field area.

  20. IMAGING AND SPECTROSCOPIC OBSERVATIONS OF MAGNETIC RECONNECTION AND CHROMOSPHERIC EVAPORATION IN A SOLAR FLARE

    SciTech Connect

    Tian, Hui; Reeves, Katharine K.; Raymond, John C.; Chen, Bin; Murphy, Nicholas A.; Li, Gang; Guo, Fan; Liu, Wei

    2014-12-20

    Magnetic reconnection is believed to be the dominant energy release mechanism in solar flares. The standard flare model predicts both downward and upward outflow plasmas with speeds close to the coronal Alfvén speed. Yet, spectroscopic observations of such outflows, especially the downflows, are extremely rare. With observations of the newly launched Interface Region Imaging Spectrograph (IRIS), we report the detection of a greatly redshifted (∼125 km s{sup –1} along the line of sight) Fe XXI 1354.08 Å emission line with a ∼100 km s{sup –1} nonthermal width at the reconnection site of a flare. The redshifted Fe XXI feature coincides spatially with the loop-top X-ray source observed by RHESSI. We interpret this large redshift as the signature of downward-moving reconnection outflow/hot retracting loops. Imaging observations from both IRIS and the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory also reveal the eruption and reconnection processes. Fast downward-propagating blobs along these loops are also found from cool emission lines (e.g., Si IV, O IV, C II, Mg II) and images of AIA and IRIS. Furthermore, the entire Fe XXI line is blueshifted by ∼260 km s{sup –1} at the loop footpoints, where the cool lines mentioned above all exhibit obvious redshift, a result that is consistent with the scenario of chromospheric evaporation induced by downward-propagating nonthermal electrons from the reconnection site.

  1. The Cassini Campaign observations of the Jupiter aurora by the Ultraviolet Imaging Spectrograph and the Space Telescope Imaging Spectrograph

    NASA Astrophysics Data System (ADS)

    Ajello, Joseph M.; Pryor, Wayne; Esposito, Larry; Stewart, Ian; McClintock, William; Gustin, Jacques; Grodent, Denis; Gérard, J.-C.; Clarke, John T.

    2005-11-01

    We have analyzed the Cassini Ultraviolet Imaging Spectrometer (UVIS) observations of the Jupiter aurora with an auroral atmosphere two-stream electron transport code. The observations of Jupiter by UVIS took place during the Cassini Campaign. The Cassini Campaign included support spectral and imaging observations by the Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS). A major result for the UVIS observations was the identification of a large color variation between the far ultraviolet (FUV: 1100-1700 Å) and extreme ultraviolet (EUV: 800-1100 Å) spectral regions. This change probably occurs because of a large variation in the ratio of the soft electron flux (10-3000 eV) responsible for the EUV aurora to the hard electron flux (˜15-22 keV) responsible for the FUV aurora. On the basis of this result a new color ratio for integrated intensities for EUV and FUV was defined ( 4πI/4πI) which varied by approximately a factor of 6. The FUV color ratio ( 4πI/4πI) was more stable with a variation of less than 50% for the observations studied. The medium resolution (0.9 Å FWHM, G140M grating) FUV observations (1295-1345 Å and 1495-1540 Å) by STIS on 13 January 2001, on the other hand, were analyzed by a spectral modeling technique using a recently developed high-spectral resolution model for the electron-excited H 2 rotational lines. The STIS FUV data were analyzed with a model that considered the Lyman band spectrum (B Σu+1→XΣg+1) as composed of an allowed direct excitation component (X Σg+1→BΣu+1) and an optically forbidden component (X Σg+1→EF,GK,HH¯,…Σg+1 followed by the cascade transition Σg+1→BΣu+1). The medium-resolution spectral regions for the Jupiter aurora were carefully chosen to emphasize the cascade component. The ratio of the two components is a direct measurement of the mean secondary electron energy of the aurora. The mean secondary electron energy of the aurora varies between 50 and 200 eV for the polar

  2. Observation of MSTIDs in Geomagnetic Conjugate Points, observed by all-sky images of OI 630.0 nm emission

    NASA Astrophysics Data System (ADS)

    Stefanello, Michel; Schuch, Nelson Jorge; Sarzi Machado, Cristiano; Pimenta, Alexandre; Vestena Bilibio, Anderson; Amorim, Danielle; Andrioli, Vania Fatima

    Medium Scale Traveling Ionospheric Disturbances (MSTIDs) are characterized as wave-like structures which propagate in the ionospheric F region of low and medium latitudes. Its origin is attributed to electrodynamics instabilities processes explained by Perkins Plasma Instability Theory. This study presents an observation of simultaneous occurrence of Medium Scale Traveling Ionospheric Disturbance (MSTID) in both hemispheres, during geomagnetically quiet nights. All-sky images of OI 630.0 nm emission were obtained with two imagers localized in geomagnetic conjugate points: Southern Space Observatory (29.4ºS, 53.8ºW), in São Martinho da Serra, Southern Brazil, and Arecibo Observatory (18.3ºN, 66.7ºW), in Puerto Rico. Using two digisondes installed at Falkland Islands (51.4ºS, 57.5ºW) and Puerto Rico (18.5ºN, 67.1ºW), it was investigated the behavior of F region during the occurrence the MSTIDs. Data from GPS receivers installed at Santa Maria (29.7ºS, 53.7ºW) and Virgin Islands (17.7ºN, 64.7ºW) were employed to calculate the variation of the Total Electronic Content (TEC). The analysis of TEC allows to identify the occurrence of ionospheric irregularities, such as MSTIDs.

  3. Development of an AutoFlat program for the acquisition of effective flat images in the automated observation system

    NASA Astrophysics Data System (ADS)

    Yoon, Joh-Na; Kim, Yonggi; Kim, Dong-Heun; Yim, Hong-Suh

    2013-12-01

    The purpose of this study is to develop an observation program for obtaining effective flat images that are necessary for photometric observation. The development of the program was achieved by improving the existing method for obtaining twilight flat images. The existing method for obtaining twilight flat images acquires flat images by observing the sky light after sunset or light before sunrise. The decision of when to observe flat images at each night is solely dependent on the judgment of an observer, and thus the obtained flat images for particular nights may not be clean. Especially, in the case of the observatories where an automated observation system is in operation, there is a difficulty that an observer should pay attention during sunrise and sunset in order to obtain flat images. In this study, a computer program is developed to improve this inconvenience and to efficiently perform photometric observation in the observatories where an automated observation system is applied. This program can obtain flat images by calculating the time for obtaining flat images automatically and the exposure time using a numerically calculated function. When obtaining twilight flat images at dusk and at dawn, the developed program performs automated observation and provides effective flat images by acquiring appropriate exposure time considering the sunrise and sunset times that vary depending on the day of observation. The code for performing this task was added to Obs Tool II (Yoon et al. 2006), which is the automated observation system of the Chungbuk National University Observatory, and the usefulness of the developed program was examined by performing an actual automated observation. If this program is applied to other observatories where automated observation is in operation, it is expected that stable and highquality flat images could be obtained, which can be used for the pre-processing of photometric observation data.

  4. Measurements of the helium 584 Å airglow during the Cassini flyby of Venus

    NASA Astrophysics Data System (ADS)

    Gérard, J.-C.; Gustin, J.; Hubert, B.; Gladstone, G. R.; Esposito, L. W.

    2011-10-01

    The helium resonance line at 584 Å has been observed with the UltraViolet Imaging Spectrograph (UVIS) Extreme Ultraviolet channel during the flyby of Venus by Cassini at a period of high solar activity. The brightness was measured along the disk from the morning terminator up to the bright limb near local noon. The mean disk intensity was ∼320 R, reaching ∼700 R at the bright limb. These values are slightly higher than those determined from previous observations. The sensitivity of the 584 Å intensity to the helium abundance is analyzed using recent cross-sections and solar irradiance measurements at 584 Å. The intensity distribution along the UVIS footprint on the disk is best reproduced using the EUVAC solar flux model and the helium density distribution from the VTS3 empirical model. It corresponds to a helium density of 8×106 cm-3 at the level of where the CO2 is 2×1010 cm-3.

  5. Supernova Remnants and Nucleosynthesis (fos 30): Augmentation Cycle 2 Observations - Imaging

    NASA Astrophysics Data System (ADS)

    Davidsen, Arthur

    1991-07-01

    Overall program: UV and optical spectra of four supernova remnants (SNRs) will be used to study a number of problems related to abundances, grain destruction, interstellar medium properties and physical conditions in SNR shocks. Representatives of three of the main classes of SNRs (Crab-nebula like, Balmer-line and "normal") will be studied in the LMC, where reasonably low reddening permits UV observations. An oxygen-rich SNR in NGC 4449 will be observed, taking advantage of the small FOS slits to isolate the SNR from surrounding H II emission. Two M33 SNRs that were previously part of this proposal have been dropped due to time limitations. This proposal is augmented time to obtain early acq images of two LMC remnants and spectra of N49, which had early acq images in Cy. 0. NOTE: SPECTROSCOPY AND IMAGING ORIGINALLY IN THE CYCLE 2 PROPOSAL 4108 HAVE BEEN SPLIT BY STSCI INTO TWO SEPARATE PROPOSALS TO ALLOW FOR SCHEDULING OF CYCLE 2 EARLY ACQ IMAGING ( THIS PROPOSAL ) SINCE CYCLE 2 SPECTROSCOPY DEPENDS ON MEASUREMENT OF EARLY ACQ IMAGING OF OTHER TARGETS FROM EARLIER CYCLES.

  6. Spatially resolved and observer-free experimental quantification of spatial resolution in tomographic images

    SciTech Connect

    Tsekenis, S. A.; McCann, H.; Tait, N.

    2015-03-15

    We present a novel framework and experimental method for the quantification of spatial resolution of a tomography system. The framework adopts the “black box” view of an imaging system, considering only its input and output. The tomography system is locally stimulated with a step input, viz., a sharp edge. The output, viz., the reconstructed images, is analysed by Fourier decomposition of their spatial frequency components, and the local limiting spatial resolution is determined using a cut-off threshold. At no point is an observer involved in the process. The framework also includes a means of translating the quantification region in the imaging space, thus creating a spatially resolved map of objectively quantified spatial resolution. As a case-study, the framework is experimentally applied using a gaseous propane phantom measured by a well-established chemical species tomography system. A spatial resolution map consisting of 28 regions is produced. In isolated regions, the indicated performance is 4-times better than that suggested in the literature and varies by 57% across the imaging space. A mechanism based on adjacent but non-interacting beams is hypothesised to explain the observed behaviour. The mechanism suggests that, as also independently concluded by other methods, a geometrically regular beam array maintains maximum objectivity in reconstructions. We believe that the proposed framework, methodology, and findings will be of value in the design and performance evaluation of tomographic imaging arrays and systems.

  7. Method for optimizing channelized quadratic observers for binary classification of large-dimensional image datasets

    PubMed Central

    Kupinski, M. K.; Clarkson, E.

    2015-01-01

    We present a new method for computing optimized channels for channelized quadratic observers (CQO) that is feasible for high-dimensional image data. The method for calculating channels is applicable in general and optimal for Gaussian distributed image data. Gradient-based algorithms for determining the channels are presented for five different information-based figures of merit (FOMs). Analytic solutions for the optimum channels for each of the five FOMs are derived for the case of equal mean data for both classes. The optimum channels for three of the FOMs under the equal mean condition are shown to be the same. This result is critical since some of the FOMs are much easier to compute. Implementing the CQO requires a set of channels and the first- and second-order statistics of channelized image data from both classes. The dimensionality reduction from M measurements to L channels is a critical advantage of CQO since estimating image statistics from channelized data requires smaller sample sizes and inverting a smaller covariance matrix is easier. In a simulation study we compare the performance of ideal and Hotelling observers to CQO. The optimal CQO channels are calculated using both eigenanalysis and a new gradient-based algorithm for maximizing Jeffrey's divergence (J). Optimal channel selection without eigenanalysis makes the J-CQO on large-dimensional image data feasible. PMID:26366764

  8. Optical observation, image-processing, and detection of space debris in geosynchronous Earth orbit

    NASA Astrophysics Data System (ADS)

    Oda, Hiroshi; Kurosaki, Hirohisa; Yanagisawa, Toshifumi; Tagawa, Makoto

    We report on optical observations and an efficient detection method of space debris in the geosynchronous Earth orbit (GEO). We operate our new Australia Remote Observatory (ARO) where an 18 cm optical telescope with a charged-coupled device (CCD) camera covering a 3.14-degree field of view is used for GEO debris survey, and analyse datasets of successive CCD images using the line detection method (Yanagisawa and Nakajima 2005). In our operation, the exposure time of each CCD image is set to be 3 seconds, and the time interval of each images is about 4.7 seconds. We can detect faint signals (down to about 1.8 sigma of background noise) by applying the line detection method to 18 CCD images. As a result, we detected about 300 GEO objects up to magnitude of 14 among 5 nights data, and found that a certain amount of our detections are new objects that are not contained in the two-line-element (TLE) data provided by the U.S. Strategic Command (USSTRATCOM). We conclude that our ARO posses a high efficiency detection of GEO objects despite the use of comparatively-inexpensive observation and analysis system. We also describe the image-processing method specialised for the detection of GEO objects (not for usual astronomical objects like stars) in this paper.

  9. Solid Hydrogen Experiments for Atomic Propellants: Particle Formation, Imaging, Observations, and Analyses

    NASA Technical Reports Server (NTRS)

    Palaszewski, Bryan

    2005-01-01

    This report presents particle formation observations and detailed analyses of the images from experiments that were conducted on the formation of solid hydrogen particles in liquid helium. Hydrogen was frozen into particles in liquid helium, and observed with a video camera. The solid hydrogen particle sizes and the total mass of hydrogen particles were estimated. These newly analyzed data are from the test series held on February 28, 2001. Particle sizes from previous testing in 1999 and the testing in 2001 were similar. Though the 2001 testing created similar particles sizes, many new particle formation phenomena were observed: microparticles and delayed particle formation. These experiment image analyses are some of the first steps toward visually characterizing these particles, and they allow designers to understand what issues must be addressed in atomic propellant feed system designs for future aerospace vehicles.

  10. VLBI observations of SN 2011dh: imaging of the youngest radio supernova

    NASA Astrophysics Data System (ADS)

    Martí-Vidal, I.; Tudose, V.; Paragi, Z.; Yang, J.; Marcaide, J. M.; Guirado, J. C.; Ros, E.; Alberdi, A.; Pérez-Torres, M. A.; Argo, M. K.; van der Horst, A. J.; Garrett, M. A.; Stockdale, C. J.; Weiler, K. W.

    2011-11-01

    We report on the VLBI detection of supernova SN 2011dh at 22 GHz using a subset of the EVN array. The observations took place 14 days after the discovery of the supernova, thus resulting in a VLBI image of the youngest radio-loud supernova ever. We provide revised coordinates for the supernova with milli-arcsecond precision, linked to the ICRF. The recovered flux density is a factor ~2 below the EVLA flux density reported by other authors at the same frequency and epoch of our observations. This discrepancy could be due to extended emission detected with the EVLA or to calibration problems in the VLBI and/or EVLA observations.

  11. Ultraviolet imaging and spectroscopy of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Gerard, Jean-Claude

    1994-01-01

    The main scientific results of the participation of the Institute of Astrophysics (Belgium) in the NASA's Pioneer Venus mission are reported on. The data were obtained with the Pioneer Orbiter's Ultraviolet Spectrometer (POUVS). The instrument provided a morphological study of the nitric oxide ultraviolet night glow. Information concerning the altitude of the airglow emitting layer was also collected and used to constrain models of turbulent transport on the night side of the planet. Models of the odd nitrogen thermospheric chemistry and transport were developed to analyze the observations and derive the properties of the global circulation of Venus' upper atmosphere. Images of the Jovian ultraviolet aurora were obtained. The morphology and the time variations of the HI Ly-alpha and H2 Lyman and Werner bands were acquired at different longitudes. The observed distribution was compared with the results of the spectrometric observations made with the Voyager and the International Ultraviolet Explorer missions. Images concerning the Io surface albedo and Saturn's disk and ring's reflectivity were also obtained.

  12. Asteroid (4179) Toutatis size determination via optical images observed by the Chang'e-2 probe

    NASA Astrophysics Data System (ADS)

    Liu, P.; Huang, J.; Zhao, W.; Wang, X.; Meng, L.; Tang, X.

    2014-07-01

    This work is a physical and statistical study of the asteroid (4179) Toutatis using the optical images obtained by a solar panel monitor of the Chang'e-2 probe on Dec. 13, 2012 [1]. In the imaging strategy, the camera is focused at infinity. This is specially designed for the probe with its solar panels monitor's principle axis pointing to the relative velocity direction of the probe and Toutatis. The imaging strategy provides a dedicated way to resolve the size by multi-frame optical images. The inherent features of the data are: (1) almost no rotation was recorded because of the 5.41-7.35 Earth-day rotation period and the small amount of elapsed imaging time, only minutes, make the object stay in the images in a fixed position and orientation; (2) the sharpness of the upper left boundary and the vagueness of lower right boundary resulting from the direction of SAP (Sun-Asteroid-Probe angle) cause a varying accuracy in locating points at different parts of Toutatis. A common view is that direct, accurate measurements of asteroid shapes, sizes, and pole positions are now possible for larger asteroids that can be spatially resolved using the Hubble Space Telescope or large ground-based telescopes equipped with adaptive optics. For a quite complex planetary/asteroid probe study, these measurements certainly need continuous validation via a variety of ways [2]. Based on engineering parameters of the probe during the fly-by, the target spatial resolving and measuring procedures are described in the paper. Results estimated are optical perceptible size on the flyby epoch under the solar phase angles during the imaging. It is found that the perceptible size measured using the optical observations and the size derived from the radar observations by Ostro et al.~in 1995 [3], are close to one another.

  13. Optical Observation, Image-processing, and Detection of Space Debris in Geosynchronous Earth Orbit

    NASA Astrophysics Data System (ADS)

    Oda, H.; Yanagisawa, T.; Kurosaki, H.; Tagawa, M.

    2014-09-01

    We report on optical observations and an efficient detection method of space debris in the geosynchronous Earth orbit (GEO). We operate our new Australia Remote Observatory (ARO) where an 18 cm optical telescope with a charged-coupled device (CCD) camera covering a 3.14-degree field of view is used for GEO debris survey, and analyse datasets of successive CCD images using the line detection method (Yanagisawa and Nakajima 2005). In our operation, the exposure time of each CCD image is set to be 3 seconds (or 5 seconds), and the time interval of CCD shutter open is about 4.7 seconds (or 6.7 seconds). In the line detection method, a sufficient number of sample objects are taken from each image based on their shape and intensity, which includes not only faint signals but also background noise (we take 500 sample objects from each image in this paper). Then we search a sequence of sample objects aligning in a straight line in the successive images to exclude the noise sample. We succeed in detecting faint signals (down to about 1.8 sigma of background noise) by applying the line detection method to 18 CCD images. As a result, we detected about 300 GEO objects up to magnitude of 15.5 among 5 nights data. We also calculate orbits of objects detected using the Simplified General Perturbations Satellite Orbit Model 4(SGP4), and identify the objects listed in the two-line-element (TLE) data catalogue publicly provided by the U.S. Strategic Command (USSTRATCOM). We found that a certain amount of our detections are new objects that are not contained in the catalogue. We conclude that our ARO and detection method posse a high efficiency detection of GEO objects despite the use of comparatively-inexpensive observation and analysis system. We also describe the image-processing specialized for the detection of GEO objects (not for usual astronomical objects like stars) in this paper.

  14. Observation of a water-depletion region surrounding loblolly pine roots by magnetic resonance imaging

    SciTech Connect

    MacFall, J.S.; Kramer, P.J. ); Johnson, G.A. )

    1990-02-01

    Magnetic resonance imaging was used to study sand containing various amounts of water and roots of loblolly pine planted into similar sand. Spin-lattice (T1) relaxation times of sand with water contents ranging from 0 to 25% (wt/wt) ranged from 472 to 1,265 ms and increased with water content. Spin-spin (T2) relaxation times ranged from 54 to 76 ms and did not change in a discernible pattern with water content. Based on water content and measured T1 and T2 values, the signal intensity of sand/water images was predicted to increase with water content in a linear fashion, with the slop of the lines increasing with the time of acquisition repetition (TR). Measured signal intensity from images of sand with various water contents was found to follow a similar pattern. This allows interpretation of dark images of sand/water to be regions of low water content, and bright images to have comparatively greater water content. Images of loblolly pine seedling roots planted in identical sand showed the formation of a distinct water-depletion region first around the woody taproot and later showed the region extended and expanded around the lateral roots and clusters of mycorrhizal short roots. This observation strongly suggests that water uptake is occurring through the suberized region of the woody taproot.

  15. Exact confidence intervals for channelized Hotelling observer performance in image quality studies.

    PubMed

    Wunderlich, Adam; Noo, Frederic; Gallas, Brandon D; Heilbrun, Marta E

    2015-02-01

    Task-based assessments of image quality constitute a rigorous, principled approach to the evaluation of imaging system performance. To conduct such assessments, it has been recognized that mathematical model observers are very useful, particularly for purposes of imaging system development and optimization. One type of model observer that has been widely applied in the medical imaging community is the channelized Hotelling observer (CHO), which is well-suited to known-location discrimination tasks. In the present work, we address the need for reliable confidence interval estimators of CHO performance. Specifically, we show that the bias associated with point estimates of CHO performance can be overcome by using confidence intervals proposed by Reiser for the Mahalanobis distance. In addition, we find that these intervals are well-defined with theoretically-exact coverage probabilities, which is a new result not proved by Reiser. The confidence intervals are tested with Monte Carlo simulation and demonstrated with two examples comparing X-ray CT reconstruction strategies. Moreover, commonly-used training/testing approaches are discussed and compared to the exact confidence intervals. MATLAB software implementing the estimators described in this work is publicly available at http://code.google.com/p/iqmodelo/. PMID:25265629

  16. Qualities of sequential chromospheric brightenings observed in Hα and UV images

    SciTech Connect

    Kirk, Michael S.; Balasubramaniam, K. S.; Jackiewicz, Jason; McAteer, R. T. James

    2014-12-01

    Chromospheric flare ribbons observed in Hα appear well-organized when first examined: ribbons impulsively brighten, morphologically evolve, and exponentially decay back to pre-flare levels. Upon closer inspection of the Hα flares, there is often a significant number of compact areas brightening in concert with the flare eruption but are spatially separated from the evolving flare ribbon. One class of these brightenings is known as sequential chromospheric brightenings (SCBs). SCBs are often observed in the immediate vicinity of erupting flares and are associated with coronal mass ejections. In the past decade there have been several previous investigations of SCBs. These studies have exclusively relied upon Hα images to discover and analyze these ephemeral brightenings. This work employs the automated detection algorithm of Kirk et al. to extract the physical qualities of SCBs in observations of ground-based Hα images and complementary Atmospheric Imaging Assembly images in He II, C IV, and 1700 Å. The metadata produced in this tracking process are then culled using complementary Doppler velocities to isolate three distinguishable types of SCBs. From a statistical analysis, we find that the SCBs at the chromospheric Hα layer appear earlier and last longer than their corresponding signatures measured in AIA. From this multi-layer analysis, we infer that SCBs are spatially constrained to the mid-chromosphere. We also derive an energy budget to explain SCBs which have a postulated energy of not more than 0.01% of the total flare energy.

  17. Qualities of Sequential Chromospheric Brightenings Observed in Hα and UV Images

    NASA Astrophysics Data System (ADS)

    Kirk, Michael S.; Balasubramaniam, K. S.; Jackiewicz, Jason; McAteer, R. T. James

    2014-12-01

    Chromospheric flare ribbons observed in Hα appear well-organized when first examined: ribbons impulsively brighten, morphologically evolve, and exponentially decay back to pre-flare levels. Upon closer inspection of the Hα flares, there is often a significant number of compact areas brightening in concert with the flare eruption but are spatially separated from the evolving flare ribbon. One class of these brightenings is known as sequential chromospheric brightenings (SCBs). SCBs are often observed in the immediate vicinity of erupting flares and are associated with coronal mass ejections. In the past decade there have been several previous investigations of SCBs. These studies have exclusively relied upon Hα images to discover and analyze these ephemeral brightenings. This work employs the automated detection algorithm of Kirk et al. to extract the physical qualities of SCBs in observations of ground-based Hα images and complementary Atmospheric Imaging Assembly images in He II, C IV, and 1700 Å. The metadata produced in this tracking process are then culled using complementary Doppler velocities to isolate three distinguishable types of SCBs. From a statistical analysis, we find that the SCBs at the chromospheric Hα layer appear earlier and last longer than their corresponding signatures measured in AIA. From this multi-layer analysis, we infer that SCBs are spatially constrained to the mid-chromosphere. We also derive an energy budget to explain SCBs which have a postulated energy of not more than 0.01% of the total flare energy.

  18. 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.

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

    NASA Technical Reports Server (NTRS)

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

  20. Earth observation photo taken by JPL with the Shuttle Imaging Radar-A

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Earth observation photo taken by the Jet Propulsion Laboratory (JPL) with the Shuttle Imaging Radar-A (SIR-A). This image shows a 50 by 100 kilometer (30 by 60 mile) area of the Imperial Valley in Southern California and neighboring Mexico. The checkered patterns represent agricultural fields where different types of crops in different stages of growth are cultivated. The very bright areas are (top left to lower right) the U.S. towns of Brawley, Imperial, El Centro, Calexico and the Mexican city of Mexicali. The bright L-shaped line (upper right) is the All-American water canal.

  1. Internal wave observations made with an airborne synthetic aperture imaging radar

    NASA Technical Reports Server (NTRS)

    Elachi, C.; Apel, J. R.

    1976-01-01

    Synthetic aperture L-band radar flown aboard the NASA CV-990 has observed periodic striations on the ocean surface off the coast of Alaska which have been interpreted as tidally excited oceanic internal waves of less than 500 m length. These radar images are compared to photographic imagery of similar waves taken from Landsat 1. Both the radar and Landsat images reveal variations in reflectivity across each wave in a packet that range from low to high to normal. The variations point to the simultaneous existence of two mechanisms for the surface signatures of internal waves: roughening due to wave-current interactions, and smoothing due to slick formation.

  2. Dayside Proton Aurora: Comparisons between Global MHD Simulations and Image Observations

    NASA Technical Reports Server (NTRS)

    Berchem, J.; Fuselier, S. A.; Petrinec, S.; Frey, H. U.; Burch, J. L.

    2003-01-01

    The IMAGE mission provides a unique opportunity to evaluate the accuracy of current global models of the solar wind interaction with the Earth's magnetosphere. In particular, images of proton auroras from the Far Ultraviolet Instrument (FUV) onboard the IMAGE spacecraft are well suited to support investigations of the response of the Earth's magnetosphere to interplanetary disturbances. Accordingly, we have modeled two events that occurred on June 8 and July 28, 2000, using plasma and magnetic field parameters measured upstream of the bow shock as input to three-dimensional magnetohydrodynamic (MHD) simulations. This paper begins with a discussion of images of proton auroras from the FUV SI-12 instrument in comparison with the simulation results. The comparison showed a very good agreement between intensifications in the auroral emissions measured by FUV SI-12 and the enhancement of plasma flows into the dayside ionosphere predicted by the global simulations. Subsequently, the IMAGE observations are analyzed in the context of the dayside magnetosphere's topological changes in magnetic field and plasma flows inferred from the simulation results. Finding include that the global dynamics of the auroral proton precipitation patterns observed by IMAGE are consistent with magnetic field reconnection occurring as a continuous process while the iMF changes in direction and the solar wind dynamic pressure varies. The global simulations also indicate that some of the transient patterns observed by IMAGE are consistent with sporadic reconnection processes. Global merging patterns found in the simulations agree with the antiparallel merging model. though locally component merging might broaden the merging region, especially in the region where shocked solar wind discontinuities first reach the magnetopause. Finally, the simulations predict the accretion of plasma near the bow shock in the regions threaded by newly open field lines on which plasma flows into the dayside

  3. Computational and human observer image quality evaluation of low dose, knowledge-based CT iterative reconstruction

    SciTech Connect

    Eck, Brendan L.; Fahmi, Rachid; Miao, Jun; Brown, Kevin M.; Zabic, Stanislav; Raihani, Nilgoun; Wilson, David L.

    2015-10-15

    Purpose: Aims in this study are to (1) develop a computational model observer which reliably tracks the detectability of human observers in low dose computed tomography (CT) images reconstructed with knowledge-based iterative reconstruction (IMR™, Philips Healthcare) and filtered back projection (FBP) across a range of independent variables, (2) use the model to evaluate detectability trends across reconstructions and make predictions of human observer detectability, and (3) perform human observer studies based on model predictions to demonstrate applications of the model in CT imaging. Methods: Detectability (d′) was evaluated in phantom studies across a range of conditions. Images were generated using a numerical CT simulator. Trained observers performed 4-alternative forced choice (4-AFC) experiments across dose (1.3, 2.7, 4.0 mGy), pin size (4, 6, 8 mm), contrast (0.3%, 0.5%, 1.0%), and reconstruction (FBP, IMR), at fixed display window. A five-channel Laguerre–Gauss channelized Hotelling observer (CHO) was developed with internal noise added to the decision variable and/or to channel outputs, creating six different internal noise models. Semianalytic internal noise computation was tested against Monte Carlo and used to accelerate internal noise parameter optimization. Model parameters were estimated from all experiments at once using maximum likelihood on the probability correct, P{sub C}. Akaike information criterion (AIC) was used to compare models of different orders. The best model was selected according to AIC and used to predict detectability in blended FBP-IMR images, analyze trends in IMR detectability improvements, and predict dose savings with IMR. Predicted dose savings were compared against 4-AFC study results using physical CT phantom images. Results: Detection in IMR was greater than FBP in all tested conditions. The CHO with internal noise proportional to channel output standard deviations, Model-k4, showed the best trade-off between fit

  4. Interactions between Coronal Mass Ejections Viewed in Coordinated Imaging and In Situ Observations

    NASA Technical Reports Server (NTRS)

    Liu, Ying D.; Luhmann, Janet G.; Moestl, Christian; Martinez-Oliveros, Juan C.; Bale, Stewart D.; Lin, Robert P.; Harrison, Richard A.; Temmer, Manuela; Webb, David F.; Odstrcil, Dusan

    2013-01-01

    The successive coronal mass ejections (CMEs) from 2010 July 30 - August 1 present us the first opportunity to study CME-CME interactions with unprecedented heliospheric imaging and in situ observations from multiple vantage points. We describe two cases of CME interactions: merging of two CMEs launched close in time and overtaking of a preceding CME by a shock wave. The first two CMEs on August 1 interact close to the Sun and form a merged front, which then overtakes the July 30 CME near 1 AU, as revealed by wide-angle imaging observations. Connections between imaging observations and in situ signatures at 1 AU suggest that the merged front is a shock wave, followed by two ejecta observed at Wind which seem to have already merged. In situ measurements show that the CME from July 30 is being overtaken by the shock at 1 AU and is significantly compressed, accelerated and heated. The interaction between the preceding ejecta and shock also results in variations in the shock strength and structure on a global scale, as shown by widely separated in situ measurements from Wind and STEREO B. These results indicate important implications of CME-CME interactions for shock propagation, particle acceleration and space weather forecasting.

  5. Current and future solar observation using focusing hard X-ray imagers

    NASA Astrophysics Data System (ADS)

    Glesener, Lindsay; Caspi, Amir; Christe, Steven; Hannah, Iain; Hudson, Hugh S.; Hurford, Gordon J.; Grefenstette, Brian; Krucker, Sam; Marsh, Andrew; Mewaldt, Richard A.; Pivovaroff, Michael; Shih, Albert Y.; Smith, David M.; Vogel, Julia; White, Stephen M.

    2014-06-01

    The efficient processes that accelerate particles in solar flares are not currently understood. Hard X-rays (HXRs) are one of the best diagnostics of flare-accelerated electrons, and therefore of acceleration processes. Past and current solar HXR observers rely on indirect Fourier imaging and thus lack the necessary sensitivity and imaging dynamic range to make detailed studies of faint HXR sources in the solar corona (where particle acceleration is thought to occur). A future generation of solar HXR observers will instead likely rely on direct HXR focusing, which can provide far superior sensitivity and imaging dynamic range.The first wave of focused solar HXR studies is already underway, including sounding rocket and high-altitude balloon payloads, and, in the near future, solar observation by the NuSTAR astrophysics observatory. This poster will (1) summarize the capabilities of current solar HXR instruments, comparing the science that can be done from each platform, and (2) discuss the scientific power of a future, dedicated, spaceborne observatory optimized to observe HXRs from the Sun.

  6. Structural anomalies in undoped Gallium Arsenide observed in high resolution diffraction imaging with monochromatic synchrotron radiation

    NASA Technical Reports Server (NTRS)

    Steiner, B.; Kuriyama, M.; Dobbyn, R. C.; Laor, U.; Larson, D.; Brown, M.

    1988-01-01

    Novel, streak-like disruption features restricted to the plane of diffraction have recently been observed in images obtained by synchrotron radiation diffraction from undoped, semi-insulating gallium arsenide crystals. These features were identified as ensembles of very thin platelets or interfaces lying in (110) planes, and a structural model consisting of antiphase domain boundaries was proposed. We report here the other principal features observed in high resolution monochromatic synchrotron radiation diffraction images: (quasi) cellular structure; linear, very low-angle subgrain boundaries in (110) directions, and surface stripes in a (110) direction. In addition, we report systematic differences in the acceptance angle for images involving various diffraction vectors. When these observations are considered together, a unifying picture emerges. The presence of ensembles of thin (110) antiphase platelet regions or boundaries is generally consistent not only with the streak-like diffraction features but with the other features reported here as well. For the formation of such regions we propose two mechanisms, operating in parallel, that appear to be consistent with the various defect features observed by a variety of techniques.

  7. GEOMETRIC TRIANGULATION OF IMAGING OBSERVATIONS TO TRACK CORONAL MASS EJECTIONS CONTINUOUSLY OUT TO 1 AU

    SciTech Connect

    Liu Ying; Luhmann, Janet G.; Bale, Stuart D.; Lin, Robert P.; Davies, Jackie A.; Vourlidas, Angelos

    2010-02-10

    We describe a geometric triangulation technique, based on time-elongation maps constructed from imaging observations, to track coronal mass ejections (CMEs) continuously in the heliosphere and predict their impact on the Earth. Taking advantage of stereoscopic imaging observations from the Solar Terrestrial Relations Observatory, this technique can determine the propagation direction and radial distance of CMEs from their birth in the corona all the way to 1 AU. The efficacy of the method is demonstrated by its application to the 2008 December 12 CME, which manifests as a magnetic cloud (MC) from in situ measurements at the Earth. The predicted arrival time and radial velocity at the Earth are well confirmed by the in situ observations around the MC. Our method reveals non-radial motions and velocity changes of the CME over large distances in the heliosphere. It also associates the flux-rope structure measured in situ with the dark cavity of the CME in imaging observations. Implementation of the technique, which is expected to be a routine possibility in the future, may indicate a substantial advance in CME studies as well as space weather forecasting.

  8. Solar Flares Observed with the Ramaty High Energy Solar Spectroscopic Imager (RHESSI)

    NASA Technical Reports Server (NTRS)

    Holman, Gordon D.

    2004-01-01

    Solar flares are impressive examples of explosive energy release in unconfined, magnetized plasma. It is generally believed that the flare energy is derived from the coronal magnetic field. However, we have not been able to establish the specific energy release mechanism(s) or the relative partitioning of the released energy between heating, particle acceleration (electrons and ions), and mass motions. NASA's RHESSI Mission was designed to study the acceleration and evolution of electrons and ions in flares by observing the X-ray and gamma-ray emissions these energetic particles produce. This is accomplished through the combination of high-resolution spectroscopy and spectroscopic imaging, including the first images of flares in gamma rays. RHESSI has observed over 12,000 solar flares since its launch on February 5, 2002. I will demonstrate how we use the RHESSI spectra to deduce physical properties of accelerated electrons and hot plasma in flares. Using images to estimate volumes, w e typically find that the total energy in accelerated electrons is comparable to that in the thermal plasma. I will also present flare observations that provide strong support for the presence of magnetic reconnection in a large-scale, vertical current sheet in the solar corona. RHESSI observations such as these are allowing us to probe more deeply into the physics of solar flares.

  9. Geometric Triangulation of Imaging Observations to Track Coronal Mass Ejections Continuously Out to 1 AU

    NASA Astrophysics Data System (ADS)

    Liu, Ying; Davies, Jackie A.; Luhmann, Janet G.; Vourlidas, Angelos; Bale, Stuart D.; Lin, Robert P.

    2010-02-01

    We describe a geometric triangulation technique, based on time-elongation maps constructed from imaging observations, to track coronal mass ejections (CMEs) continuously in the heliosphere and predict their impact on the Earth. Taking advantage of stereoscopic imaging observations from the Solar Terrestrial Relations Observatory, this technique can determine the propagation direction and radial distance of CMEs from their birth in the corona all the way to 1 AU. The efficacy of the method is demonstrated by its application to the 2008 December 12 CME, which manifests as a magnetic cloud (MC) from in situ measurements at the Earth. The predicted arrival time and radial velocity at the Earth are well confirmed by the in situ observations around the MC. Our method reveals non-radial motions and velocity changes of the CME over large distances in the heliosphere. It also associates the flux-rope structure measured in situ with the dark cavity of the CME in imaging observations. Implementation of the technique, which is expected to be a routine possibility in the future, may indicate a substantial advance in CME studies as well as space weather forecasting.

  10. TESTING THE NO-HAIR THEOREM WITH OBSERVATIONS IN THE ELECTROMAGNETIC SPECTRUM. II. BLACK HOLE IMAGES

    SciTech Connect

    Johannsen, Tim; Psaltis, Dimitrios E-mail: dpsaltis@email.arizona.ed

    2010-07-20

    According to the no-hair theorem, all astrophysical black holes are fully described by their masses and spins. This theorem can be tested observationally by measuring (at least) three different multipole moments of the spacetimes of black holes. In this paper, we analyze images of black holes within a framework that allows us to calculate observables in the electromagnetic spectrum as a function of the mass, spin, and, independently, the quadrupole moment of a black hole. We show that a deviation of the quadrupole moment from the expected Kerr value leads to images of black holes that are either prolate or oblate depending on the sign and magnitude of the deviation. In addition, there is a ring-like structure around the black hole shadow with a diameter of {approx}10 black hole masses that is substantially brighter than the image of the underlying accretion flow and that is independent of the astrophysical details of accretion flow models. We show that the shape of this ring depends directly on the mass, spin, and quadrupole moment of the black hole and can be used for an independent measurement of all three parameters. In particular, we demonstrate that this ring is highly circular for a Kerr black hole with a spin a {approx}< 0.9 M, independent of the observer's inclination, but becomes elliptical and asymmetric if the no-hair theorem is violated. Near-future very long baseline interferometric observations of Sgr A* will image this ring and may allow for an observational test of the no-hair theorem.

  11. Direct observation of receptors and images in simple and compound eyes.

    PubMed

    Land, M F

    1990-01-01

    The relation between the quality of the optical image and the fineness of the retinal mosaic has been studied in eyes of three different optical types: the simple eyes of spiders, the superposition compound eyes of moths, and the apposition compound eyes of butterflies. In all three it is possible to observe both the receptor mosaic and the image in the living eye, using appropriate ophthalmoscopic techniques. Whereas in humans the retinal sampling frequency approaches the optical cut-off frequency quite closely, in diurnal insects of both types the image is undersampled by a factor of 2-3, and in crepuscular spiders this factor may be greater than 100. Reasons for these differences are discussed. PMID:2288086

  12. Use of dust storm observations on satellite images to identify areas vulnerable to severe wind erosion

    USGS Publications Warehouse

    Breed, C.S.; McCauley, J.F.

    1986-01-01

    Blowing dust is symptomatic of severe wind erosion and deterioration of soils in areas undergoing dessication and/or devegetation. Dust plumes on satellite images can commonly be traced to sources in marginally arable semiarid areas where protective lag gravels or vegetation have been removed and soils are dry, as demonstrated for the Portales Valley, New Mexico. Images from Landsat and manned orbiters such as Skylab and the Space Shuttle are useful for illustrating the regional relations of airborne dust plumes to source areas. Geostationary satellites such as GOES are useful in tracking the time-histories of episodic dust storms. These events sometimes go unrecognized by weather observers and are the precursors of long-term land degradation trends. In areas where soil maps and meteorological data are inadequate, satellite images provide a means for identifying problem areas where measures are needed to control or mitigate wind erosion. ?? 1986 D. Reidel Publishing Company.

  13. Local Force Interactions and Image Contrast Reversal on Graphite Observed with Noncontact Atomic Force Microscopy

    NASA Astrophysics Data System (ADS)

    Dagdeviren, Omur; Goetzen, Jan; Altman, Eric; Schwarz, Udo

    Surface interactions of graphene-based nanostructures remain a topic of considerable interest in nanotechnology. Similarly, tip-dependent imaging contrasts have attracted attention as they allow conclusions to be made about the surface's chemical structure and local reactivity. In this talk, we present noncontact atomic force microscopy data recorded in the attractive regime on highly oriented pyrolytic graphite that reveals image contrast reversal for the first time. While larger tip-sample separations feature bright spots on atomic sites, the maximum of the tip-sample interaction flips to the hollow site positions upon further approach, which represents the contrast predominantly observed in previous studies during attractive-mode imaging. This cross over of the local chemical interaction is confirmed in force spectroscopy experiments. The results will be discussed in light of recent theoretical simulations that have predicted the occurrence of such contrast reversal for specific tip terminations.

  14. The capability of the ultraviolet imaging telescope for observing interstellar dust

    NASA Technical Reports Server (NTRS)

    Stecher, Theodore P.

    1989-01-01

    The Ultraviolet Imaging Telescope (UIT) was designed to be able to obtain deep images of nearby galaxies with a single frame. This ability makes it ideal for many imaging problems of the interstellar dust. The instrument has a forty arc-minute field of view with two arc-second resolution. It has 11 ultraviolet filters and a grating which is used as a grism for full field spectroscopy. In a thirty minute exposure (one orbital night) the limiting magnitude for hot objects is V = 25, or a UV mag of 22 for point sources and a UV mag of 26 for extended sources. Programs are planned for the observation of dust in reflection nebulae H II regions, planetaries, dark nebulae, the diffuse galactic light, and dust in other galaxies are planned. The UIT was integrated into the Astro Spacelab Payload and is scheduled to be launched on the Columbia in Nov. 1989.

  15. Theoretical Model Images and Spectra for Comparison with HESSI and Microwave Observations of Solar Flares

    NASA Technical Reports Server (NTRS)

    Fisher, Richard R. (Technical Monitor); Holman, G. D.; Sui, L.; McTiernan, J. M.; Petrosian, V.

    2003-01-01

    We have computed bremsstrahlung and gyrosynchrotron images and spectra from a model flare loop. Electrons with a power-law energy distribution are continuously injected at the top of a semi-circular magnetic loop. The Fokker-Planck equation is integrated to obtain the steady-state electron distribution throughout the loop. Coulomb scattering and energy losses and magnetic mirroring are included in the model. The resulting electron distributions are used to compute the radiative emissions. Sample images and spectra are presented. We are developing these models for the interpretation of the High Energy Solar Spectroscopic Imager (HESSI) x-ray/gamma ray data and coordinated microwave observations. The Fokker-Planck and radiation codes are available on the Web at http://hesperia.gsfc.nasa.gov/hessi/modelware.htm This work is supported in part by the NASA Sun-Earth Connection Program.

  16. Three-dimensional numerical simulation of MHD waves observed by the Extreme Ultraviolet Imaging Telescope

    NASA Astrophysics Data System (ADS)

    Wu, S. T.; Zheng, Huinan; Wang, S.; Thompson, B. J.; Plunkett, S. P.; Zhao, X. P.; Dryer, M.

    2001-11-01

    We investigate the global large amplitude waves propagating across the solar disk as observed by the SOHO/Extreme Ultraviolet Imaging Telescope (EIT). These waves appear to be similar to those observed in Hα in the chromosphere and which are known as ``Moreton waves,'' associated with large solar flares [Moreton, 1960, 1964]. Uchida [1968] interpreted these Moreton waves as the propagation of a hydromagnetics disturbance in the corona with its wavefront intersecting the chromosphere to produce the Moreton wave as observed in movie sequences of Hα images. To search for an understanding of the physical characteristics of these newly observed EIT waves, we constructed a three-dimensional, time-dependent, numerical magnetohydrodynamic (MHD) model. Measured global magnetic fields, obtained from the Wilcox Solar Observatory (WSO) at Stanford University, are used as the initial magnetic field to investigate hydromagnetics wave propagation in a three-dimensional spherical geometry. Using magnetohydrodynamic wave theory together with simulation, we are able to identify these observed EIT waves as fast mode MHD waves dominated by the acoustic mode, called magnetosonic waves. The results to be presented include the following: (1) comparison of observed and simulated morphology projected on the disk and the distance-time curves on the solar disk; (2) three-dimensional evolution of the disturbed magnetic field lines at various viewing angles; (3) evolution of the plasma density profile at a specific location as a function of latitude; and (4) computed Friedrich's diagrams to identify the MHD wave characteristics.

  17. Observations of barium ion jets in the magnetosphere using Doppler imaging systems and very sensitive imaging systems using imaging photon detectors

    NASA Technical Reports Server (NTRS)

    Rees, D.; Conboy, J.; Heinz, W.; Heppner, J. P.

    1985-01-01

    Observations of four shaped charge releases from rockets launched from Alaska are described. Results demonstrate that imaging and Doppler imaging instruments, based on exploiting the imaging photon detector, provide additional insight into the motion and development of low intensity targets such as the fast ion jets produced by shaped charge releases. It is possible to trace the motion of fast ion jets to very great distances, of the order of 50,000 km, outward along the Earth's magnetic field, when the conditions are suitable for the outward (upward) motion and/or acceleration of such ion jets. It is shown that ion jets, which fade below the lower sensitivity threshold of previous instruments, do not always disappear. There is no evidence of an abrupt field-aligned shear-type acceleration.

  18. Examining Periodic Solar-Wind Density Structures Observed in the SECCHI Heliospheric Imagers

    NASA Technical Reports Server (NTRS)

    Viall, Nicholeen M.; Spence, Harlan E.; Vourlidas, Angelos; Howard, Russell

    2010-01-01

    We present an analysis of small-scale, periodic, solar-wind density enhancements (length scales as small as approximately equals 1000 Mm) observed in images from the Heliospheric Imager (HI) aboard STEREO-A. We discuss their possible relationship to periodic fluctuations of the proton density that have been identified at 1 AU using in-situ plasma measurements. Specifically, Viall, Kepko, and Spence examined 11 years of in-situ solar-wind density measurements at 1 AU and demonstrated that not only turbulent structures, but also nonturbulent, periodic density structures exist in the solar wind with scale sizes of hundreds to one thousand Mm. In a subsequent paper, Viall, Spence, and Kasper analyzed the alpha-to-proton solar-wind abundance ratio measured during one such event of periodic density structures, demonstrating that the plasma behavior was highly suggestive that either temporally or spatially varying coronal source plasma created those density structures. Large periodic density structures observed at 1 AU, which were generated in the corona, can be observable in coronal and heliospheric white-light images if they possess sufficiently high density contrast. Indeed, we identify such periodic density structures as they enter the HI field of view and follow them as they advect with the solar wind through the images. The smaller, periodic density structures that we identify in the images are comparable in size to the larger structures analyzed in-situ at 1 AU, yielding further evidence that periodic density enhancements are a consequence of coronal activity as the solar wind is formed.

  19. Fabry-Pérot based narrow band imager for solar filament observations

    NASA Astrophysics Data System (ADS)

    Dhara, Sajal Kumar; Ravindra, Belur; Banyal, Ravinder Kumar

    2016-01-01

    We have recently developed a narrow band imager (NBI) using an air gap based Fabry-Pérot (FP) interferometer at the Indian Institute of Astrophysics, Bangalore. Narrow band imaging is achieved by using an FP interferometer working in combination with an order sorting pre-filter. The NBI can be tuned to a different wavelength position on the line profile by changing the plate separation of the FP. The interferometer has a 50 mm clear aperture with a bandpass of ∼247.8 mÅ and a free spectral range of ∼5.3 Å at λ = 656.3 nm. The developed NBI is used to observe the solar filament in the Hα wavelength. The instrument is being used to image the Sun at chromospheric height and it is also able to scan the Hα spectral line profile at different wavelength positions. We have also made Doppler velocity maps at chromospheric height by taking the blue and red wing images at ±176 mÅ wavelength positions separately away from the line center of the spectral line. In this paper, we present a description of the NBI including lab test results of individual components and some initial observations carried out with this instrument.

  20. Multi-observation PET image analysis for patient follow-up quantitation and therapy assessment

    NASA Astrophysics Data System (ADS)

    David, S.; Visvikis, D.; Roux, C.; Hatt, M.

    2011-09-01

    In positron emission tomography (PET) imaging, an early therapeutic response is usually characterized by variations of semi-quantitative parameters restricted to maximum SUV measured in PET scans during the treatment. Such measurements do not reflect overall tumor volume and radiotracer uptake variations. The proposed approach is based on multi-observation image analysis for merging several PET acquisitions to assess tumor metabolic volume and uptake variations. The fusion algorithm is based on iterative estimation using a stochastic expectation maximization (SEM) algorithm. The proposed method was applied to simulated and clinical follow-up PET images. We compared the multi-observation fusion performance to threshold-based methods, proposed for the assessment of the therapeutic response based on functional volumes. On simulated datasets the adaptive threshold applied independently on both images led to higher errors than the ASEM fusion and on clinical datasets it failed to provide coherent measurements for four patients out of seven due to aberrant delineations. The ASEM method demonstrated improved and more robust estimation of the evaluation leading to more pertinent measurements. Future work will consist in extending the methodology and applying it to clinical multi-tracer datasets in order to evaluate its potential impact on the biological tumor volume definition for radiotherapy applications.

  1. Observation of image pair creation and annihilation from superluminal scattering sources.

    PubMed

    Clerici, Matteo; Spalding, Gabriel C; Warburton, Ryan; Lyons, Ashley; Aniculaesei, Constantin; Richards, Joseph M; Leach, Jonathan; Henderson, Robert; Faccio, Daniele

    2016-04-01

    The invariance of the speed of light is one of the foundational pillars of our current understanding of the universe. It implies a series of consequences related to our perception of simultaneity and, ultimately, of time itself. Whereas these consequences are experimentally well studied in the case of subluminal motion, the kinematics of superluminal motion lack direct evidence or even a clear experimental approach. We investigate kinematic effects associated with the superluminal motion of a light source. By using high-temporal-resolution imaging techniques, we directly demonstrate that if the source approaches an observer at superluminal speeds, the temporal ordering of events is inverted and its image appears to propagate backward. Moreover, for a source changing its speed and crossing the interface between subluminal and superluminal propagation regions, we observe image pair annihilation and creation, depending on the crossing direction. These results are very general and show that, regardless of the emitter speed, it is not possible to unambiguously determine the kinematics of an event from imaging and time-resolved measurements alone. This has implications not only for light, but also, for example, for sound and other wave phenomena. PMID:27152347

  2. Imaging-based observations of low-latitude auroras during 2001-2004 at Nayoro, Japan

    NASA Astrophysics Data System (ADS)

    Suzuki, Hidehiko; Chino, Haruka; Sano, Yasuo; Kadokura, Akira; Ejiri, Mitsumu K.; Taguchi, Makoto

    2015-07-01

    Color images of six low-latitude auroral events observed using color digital cameras at Nayoro (142.5° E, 44.4° N), Hokkaido, Japan, from 2001 to 2004, were analyzed to determine the events' locations and times of occurrence. Geographical azimuthal and elevation angles of the images' pixels were determined precisely by using the positions of the stars captured in the images. Horizontal regions covered by these auroral events were directly indicated by mapping the color images onto geographical maps and assuming that the emission layer's altitude is the lowest or highest value of a visible-level red aurora, as determined by the OI 630.0nm emission. The estimated geomagnetic latitudes and L values of these low-latitude auroral events were in the 39-50° range and below L < 2.5, respectively. This investigation indicates that four of the six auroral events were the same as those that were reported previously based on high-sensitivity optical observations at other sites on Hokkaido (Rikubetsu and Moshiri). Although the previous study is lacking information about the maximal brightness level of the red auroral events, the present investigation suggests that these four low-latitude auroral events reached the visible level. In addition, two new events were reported in this study. The present work provides essential information such as the morphology and appearance of visible auroras, which are extremely rare in mid- or low-latitude regions.

  3. Observation of image pair creation and annihilation from superluminal scattering sources

    PubMed Central

    Clerici, Matteo; Spalding, Gabriel C.; Warburton, Ryan; Lyons, Ashley; Aniculaesei, Constantin; Richards, Joseph M.; Leach, Jonathan; Henderson, Robert; Faccio, Daniele

    2016-01-01

    The invariance of the speed of light is one of the foundational pillars of our current understanding of the universe. It implies a series of consequences related to our perception of simultaneity and, ultimately, of time itself. Whereas these consequences are experimentally well studied in the case of subluminal motion, the kinematics of superluminal motion lack direct evidence or even a clear experimental approach. We investigate kinematic effects associated with the superluminal motion of a light source. By using high-temporal-resolution imaging techniques, we directly demonstrate that if the source approaches an observer at superluminal speeds, the temporal ordering of events is inverted and its image appears to propagate backward. Moreover, for a source changing its speed and crossing the interface between subluminal and superluminal propagation regions, we observe image pair annihilation and creation, depending on the crossing direction. These results are very general and show that, regardless of the emitter speed, it is not possible to unambiguously determine the kinematics of an event from imaging and time-resolved measurements alone. This has implications not only for light, but also, for example, for sound and other wave phenomena. PMID:27152347

  4. Demonstration of Imaging Fourier Transform Spectrometer (FTS) Performance for Planetary and Geostationary Earth Observing

    NASA Technical Reports Server (NTRS)

    Revercomb, Henry E.; Sromovsky, Lawrence A.; Fry, Patrick M.; Best, Fred A.; LaPorte, Daniel D.

    2001-01-01

    The combination of massively parallel spatial sampling and accurate spectral radiometry offered by imaging FTS makes it extremely attractive for earth and planetary remote sensing. We constructed a breadboard instrument to help assess the potential for planetary applications of small imaging FTS instruments in the 1 - 5 micrometer range. The results also support definition of the NASA Geostationary Imaging FTS (GIFTS) instrument that will make key meteorological and climate observations from geostationary earth orbit. The Planetary Imaging FTS (PIFTS) breadboard is based on a custom miniaturized Bomen interferometer that uses corner cube reflectors, a wishbone pivoting voice-coil delay scan mechanism, and a laser diode metrology system. The interferometer optical output is measured by a commercial infrared camera procured from Santa Barbara Focalplane. It uses an InSb 128x128 detector array that covers the entire FOV of the instrument when coupled with a 25 mm focal length commercial camera lens. With appropriate lenses and cold filters the instrument can be used from the visible to 5 micrometers. The delay scan is continuous, but slow, covering the maximum range of +/- 0.4 cm in 37.56 sec at a rate of 500 image frames per second. Image exposures are timed to be centered around predicted zero crossings. The design allows for prediction algorithms that account for the most recent fringe rate so that timing jitter produced by scan speed variations can be minimized. Response to a fixed source is linear with exposure time nearly to the point of saturation. Linearity with respect to input variations was demonstrated to within 0.16% using a 3-point blackbody calibration. Imaging of external complex scenes was carried out at low and high spectral resolution. These require full complex calibration to remove background contributions that vary dramatically over the instrument FOV. Testing is continuing to demonstrate the precise radiometric accuracy and noise characteristics.

  5. Potential for observing and discriminating impact craters and comparable volcanic landforms on Magellan radar images

    NASA Technical Reports Server (NTRS)

    Ford, J. P.

    1989-01-01

    Observations of small terrestrial craters by Seasat synthetic aperture radar (SAR) at high resolution (approx. 25 m) and of comparatively large Venusian craters by Venera 15/16 images at low resolution (1000 to 2000 m) and shorter wavelength show similarities in the radar responses to crater morphology. At low incidence angles, the responses are dominated by large scale slope effects on the order of meters; consequently it is difficult to locate the precise position of crater rims on the images. Abrupt contrasts in radar response to changing slope (hence incidence angle) across a crater produce sharp tonal boundaries normal to the illumination. Crater morphology that is radially symmetrical appears on images to have bilateral symmetry parallel to the illumination vector. Craters are compressed in the distal sector and drawn out in the proximal sector. At higher incidence angles obtained with the viewing geometry of SIR-A, crater morphology appears less compressed on the images. At any radar incidence angle, the distortion of a crater outline is minimal across the medial sector, in a direction normal to the illumination. Radar bright halos surround some craters imaged by SIR-A and Venera 15 and 16. The brightness probably denotes the radar response to small scale surface roughness of the surrounding ejecta blankets. Similarities in the radar responses of small terrestrial impact craters and volcanic craters of comparable dimensions emphasize the difficulties in discriminating an impact origin from a volcanic origin in the images. Similar difficulties will probably apply in discriminating the origin of small Venusian craters, if they exist. Because of orbital considerations, the nominal incidence angel of Magellan radar at the center of the imaging swath will vary from about 45 deg at 10 deg N latitude to about 16 deg at the north pole and at 70 deg S latitude. Impact craters and comparable volcanic landforms will show bilateral symmetry parallel to the illumination

  6. Potential for observing and discriminating impact craters and comparable volcanic landforms on Magellan radar images

    NASA Astrophysics Data System (ADS)

    Ford, J. P.

    Observations of small terrestrial craters by Seasat synthetic aperture radar (SAR) at high resolution (approx. 25 m) and of comparatively large Venusian craters by Venera 15/16 images at low resolution (1000 to 2000 m) and shorter wavelength show similarities in the radar responses to crater morphology. At low incidence angles, the responses are dominated by large scale slope effects on the order of meters; consequently it is difficult to locate the precise position of crater rims on the images. Abrupt contrasts in radar response to changing slope (hence incidence angle) across a crater produce sharp tonal boundaries normal to the illumination. Crater morphology that is radially symmetrical appears on images to have bilateral symmetry parallel to the illumination vector. Craters are compressed in the distal sector and drawn out in the proximal sector. At higher incidence angles obtained with the viewing geometry of SIR-A, crater morphology appears less compressed on the images. At any radar incidence angle, the distortion of a crater outline is minimal across the medial sector, in a direction normal to the illumination. Radar bright halos surround some craters imaged by SIR-A and Venera 15 and 16. The brightness probably denotes the radar response to small scale surface roughness of the surrounding ejecta blankets. Similarities in the radar responses of small terrestrial impact craters and volcanic craters of comparable dimensions emphasize the difficulties in discriminating an impact origin from a volcanic origin in the images. Similar difficulties will probably apply in discriminating the origin of small Venusian craters, if they exist. Because of orbital considerations, the nominal incidence angel of Magellan radar at the center of the imaging swath will vary from about 45 deg at 10 deg N latitude to about 16 deg at the north pole and at 70 deg S latitude. Impact craters and comparable volcanic landforms will show bilateral symmetry parallel to the illumination

  7. Characteristics of the mirror image of precipitation observed by TRMM precipitation radar

    NASA Astrophysics Data System (ADS)

    Li, Ji; Nakamura, Kenji

    2000-12-01

    Mirror image is a virtual image of precipitation below the ocean surface when we use an airborne or a spaceborne radar to view the rainfall over ocean. It is due to a double reflection, that is energy reflected form the sea surface goes to the precipitation and back to the radar via a second reflection at sea surface. We investigated the mirror image characteristics using TRMM Precipitation Radar data and found: 1) The radar can detect the mirror image clearly over the ocean, 2) the mirror image echo corresponds well to the direct rain echo at nadir and near nadir incidence angle, 3) in a weak rain region, mirror echo intensity is nearly proportional to the direct echo power except near noise level, 4) in the strong rain region, rain attenuation effect clearly appears, and 5) the ratio of mirror echo power to direct echo power is affected by the rain attenuation which varies with the bright band height and the range of the target rain from surface. Further, we performed a simple simulation in order to confirm the above characteristics. The signal fluctuation, noise contamination, rain attention and surface cross section are taken into account in the simulation, and the results of simulation confirmed the observation results.

  8. High-contrast imaging with Spitzer: deep observations of Vega, Fomalhaut, and ɛ Eridani

    NASA Astrophysics Data System (ADS)

    Janson, Markus; Quanz, Sascha P.; Carson, Joseph C.; Thalmann, Christian; Lafrenière, David; Amara, Adam

    2015-02-01

    Stars with debris disks are intriguing targets for direct-imaging exoplanet searches, owing both to previous detections of wide planets in debris disk systems, and to commonly existing morphological features in the disks themselves that may be indicative of a planetary influence. Here we present observations of three of the most nearby young stars, which are also known to host massive debris disks: Vega, Fomalhaut, and ɛ Eri. The Spitzer Space Telescope is used at a range of orientation angles for each star to supply a deep contrast through angular differential imaging combined with high-contrast algorithms. The observations provide the opportunity to probe substantially colder bound planets (120-330 K) than is possible with any other technique or instrument. For Vega, some apparently very red candidate point sources detected in the 4.5 μm image remain to be tested for common proper motion. The images are sensitive to ~2 Mjup companions at 150 AU in this system. The observations presented here represent the first search for planets around Vega using Spitzer. The upper 4.5 μm flux limit on Fomalhaut b could be further constrained relative to previous data. In the case of ɛ Eri, planets below both the effective temperature and the mass of Jupiter could be probed from 80 AU and outward, although no such planets were found. The data sensitively probe the regions around the edges of the debris rings in the systems where planets can be expected to reside. These observations validate previous results showing that more than an order of magnitude improvement in performance in the contrast-limited regime can be acquired with respect to conventional methods by applying sophisticated high-contrast techniques to space-based telescopes, thanks to the high degree of PSF stability provided in this environment.

  9. Atmospheric Correction Prototype Algorithm for High Spatial Resolution Multispectral Earth Observing Imaging Systems

    NASA Technical Reports Server (NTRS)

    Pagnutti, Mary

    2006-01-01

    This viewgraph presentation reviews the creation of a prototype algorithm for atmospheric correction using high spatial resolution earth observing imaging systems. The objective of the work was to evaluate accuracy of a prototype algorithm that uses satellite-derived atmospheric products to generate scene reflectance maps for high spatial resolution (HSR) systems. This presentation focused on preliminary results of only the satellite-based atmospheric correction algorithm.

  10. Expanding Imaging Capabilities for Microfluidics: Applicability of Darkfield Internal Reflection Illumination (DIRI) to Observations in Microfluidics

    PubMed Central

    Kawano, Yoshihiro; Otsuka, Chino; Sanzo, James; Higgins, Christopher; Nirei, Tatsuo; Schilling, Tobias; Ishikawa, Takuji

    2015-01-01

    Microfluidics is used increasingly for engineering and biomedical applications due to recent advances in microfabrication technologies. Visualization of bubbles, tracer particles, and cells in a microfluidic device is important for designing a device and analyzing results. However, with conventional methods, it is difficult to observe the channel geometry and such particles simultaneously. To overcome this limitation, we developed a Darkfield Internal Reflection Illumination (DIRI) system that improved the drawbacks of a conventional darkfield illuminator. This study was performed to investigate its utility in the field of microfluidics. The results showed that the developed system could clearly visualize both microbubbles and the channel wall by utilizing brightfield and DIRI illumination simultaneously. The methodology is useful not only for static phenomena, such as clogging, but also for dynamic phenomena, such as the detection of bubbles flowing in a channel. The system was also applied to simultaneous fluorescence and DIRI imaging. Fluorescent tracer beads and channel walls were observed clearly, which may be an advantage for future microparticle image velocimetry (μPIV) analysis, especially near a wall. Two types of cell stained with different colors, and the channel wall, can be recognized using the combined confocal and DIRI system. Whole-slide imaging was also conducted successfully using this system. The tiling function significantly expands the observing area of microfluidics. The developed system will be useful for a wide variety of engineering and biomedical applications for the growing field of microfluidics. PMID:25748425

  11. Comet Shoemaker-Levy 9/Jupiter collision observed with a high resolution speckle imaging system

    SciTech Connect

    Gravel, D.

    1994-11-15

    During the week of July 16, 1994, comet Shoemaker-Levy 9, broken into 20 plus pieces by tidal forces on its last orbit, smashed into the planet Jupiter, releasing the explosive energy of 500 thousand megatons. A team of observers from LLNL used the LLNL Speckle Imaging Camera mounted on the University of California`s Lick Observatory 3 Meter Telescope to capture continuous sequences of planet images during the comet encounter. Post processing with the bispectral phase reconstruction algorithm improves the resolution by removing much of the blurring due to atmospheric turbulence. High resolution images of the planet surface showing the aftermath of the impact are probably the best that were obtained from any ground-based telescope. We have been looking at the regions of the fragment impacts to try to discern any dynamic behavior of the spots left on Jupiter`s cloud tops. Such information can lead to conclusions about the nature of the comet and of Jupiter`s atmosphere. So far, the Hubble Space Telescope has observed expanding waves from the G impact whose mechanism is enigmatic since they appear to be too slow to be sound waves and too fast to be gravity waves, given the present knowledge of Jupiter`s atmosphere. Some of our data on the G and L impact region complements the Hubble observations but, so far, is inconclusive about spot dynamics.

  12. Interaction between Coronal Mass Ejections Viewed in Coordinated Imaging and In Situ Observations

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Luhmann, J. G.; Moestl, C.; Martinez Oliveros, J. C.; Harrison, R.; Temmer, M.; Bale, S.; Lin, R. P.

    2011-12-01

    Interaction between coronal mass ejections (CMEs), which is expected to be a frequent phenomenon, has important implications for both space weather and basic plasma physics. First, the interaction alters the global heliospheric configuration, which may lead to favorable conditions for geomagnetic storm generation. Second, the interaction implies significant energy and momentum transfer between the interacting CMEs where magnetic reconnection may take place. Third, in case a shock is driven by the trailing CME, interesting physical processes may occur when the shock is propagating through the preceding one, such as modifications in the shock strength, particle intensity and transport. There are successive CMEs on July 30 - August 1, 2011, which presents us the first opportunity to study CME-CME interaction with unprecedented heliospheric imaging and in situ observations from a fleet of spacecraft. The first two CMEs on August 1 interact close to the Sun and form a merged front, which then overtakes the July 30 CME near 1 AU, as revealed by wide-angle imaging observations. In situ measurements indicate that the first two CMEs on August 1 seem to have already merged at 0.7 and 1 AU, and at 1 AU their shock is propagating into the CME from July 30. We will report and discuss the CME-CME interaction signatures from the coordinated imaging and in situ observations in this presentation.

  13. Versatile illumination platform and fast optical switch to give standard observation camera gated active imaging capacity

    NASA Astrophysics Data System (ADS)

    Grasser, R.; Peyronneaudi, Benjamin; Yon, Kevin; Aubry, Marie

    2015-10-01

    CILAS, subsidiary of Airbus Defense and Space, develops, manufactures and sales laser-based optronics equipment for defense and homeland security applications. Part of its activity is related to active systems for threat detection, recognition and identification. Active surveillance and active imaging systems are often required to achieve identification capacity in case for long range observation in adverse conditions. In order to ease the deployment of active imaging systems often complex and expensive, CILAS suggests a new concept. It consists on the association of two apparatus working together. On one side, a patented versatile laser platform enables high peak power laser illumination for long range observation. On the other side, a small camera add-on works as a fast optical switch to select photons with specific time of flight only. The association of the versatile illumination platform and the fast optical switch presents itself as an independent body, so called "flash module", giving to virtually any passive observation systems gated active imaging capacity in NIR and SWIR.

  14. THE STRUCTURE OF A SELF-GRAVITATING PROTOPLANETARY DISK AND ITS IMPLICATIONS FOR DIRECT IMAGING OBSERVATIONS

    SciTech Connect

    Muto, Takayuki

    2011-09-20

    We consider the effects of self-gravity on the hydrostatic balance in the vertical direction of a gaseous disk and discuss the possible signature of the self-gravity that may be captured by direct imaging observations of protoplanetary disks in the future. In this paper, we consider a vertically isothermal disk in order to isolate the effects of self-gravity. The specific disk model we consider in this paper is the one with a radial surface density gap, at which the Toomre's Q-parameter of the disk varies rapidly in the radial direction. We calculate the vertical structure of the disk including the effects of self-gravity. We then calculate the scattered light and the dust thermal emission. We find that if the disk is massive enough and the effects of self-gravity come into play, a weak bump-like structure at the gap edge appears in the near-infrared (NIR) scattered light, while no such bump-like structure is seen in the submillimeter (sub-mm) dust continuum image. The appearance of the bump is caused by the variation of the height of the surface in the NIR wavelength. If such a bump-like feature is detected in future direct imaging observations, combined with sub-mm observations, it will give us useful information about the physical states of the disk.

  15. The Venus nitric oxide night airglow - Model calculations based on the Venus Thermospheric General Circulation Model

    NASA Technical Reports Server (NTRS)

    Bougher, S. W.; Gerard, J. C.; Stewart, A. I. F.; Fesen, C. G.

    1990-01-01

    The mechanism responsible for the Venus nitric oxide (0,1) delta band nightglow observed in the Pioneer Venus Orbiter UV spectrometer (OUVS) images was investigated using the Venus Thermospheric General Circulation Model (Dickinson et al., 1984), modified to include simple odd nitrogen chemistry. Results obtained for the solar maximum conditions indicate that the recently revised dark-disk average NO intensity at 198.0 nm, based on statistically averaged OUVS measurements, can be reproduced with minor modifications in chemical rate coefficients. The results imply a nightside hemispheric downward N flux of (2.5-3) x 10 to the 9th/sq cm sec, corresponding to the dayside net production of N atoms needed for transport.

  16. New color images of transient luminous events from dedicated observations on the International Space Station

    NASA Astrophysics Data System (ADS)

    Yair, Yoav; Rubanenko, Lior; Mezuman, Keren; Elhalel, Gal; Pariente, Meidad; Glickman-Pariente, Maya; Ziv, Baruch; Takahashi, Yukihiro; Inoue, Tomohiro

    2013-09-01

    During July-August 2011, Expedition 28/29 JAXA astronaut Satoshi Furukawa conducted TLE observations from the International Space Station in conjunction with the “Cosmic Shore” program produced by NHK. An EMCCD normal video-rate color TV camera was used to conduct directed observations from the Earth-pointing Cupola module. The target selection was based on the methodology developed for the MEIDEX sprite campaign on board the space shuttle Columbia in January 2003 (Ziv et al., 2004). The observation geometry was pre-determined and uploaded daily to the ISS with pointing options to limb, oblique or nadir, based on the predicted location of the storm with regards to the ISS. The pointing angle was rotated in real-time according to visual eyesight by the astronaut. We present results of 10 confirmed TLEs: 8 sprites, 1 sprite halo and 1 gigantic jet, out of <2 h of video. Sprites tend to appear in a single frame simultaneously with maximum lightning brightness. Unique images (a) from nadir of a sprite horizontally displaced form the lightning light and (b) from the oblique view of a sprite halo, enable the calculation of dimensions and volumes occupied by these TLEs. Since time stamping on the ISS images was accurate within 1 s, matching with ELF and WWLLN data for the parent lightning location is limited. Nevertheless, the results prove that the ISS is an ideal platform for lightning and TLE observations, and careful operational procedures greatly enhance the value of observation time.

  17. Imaging observations of X-ray albedo in a compact disc flare

    NASA Astrophysics Data System (ADS)

    Battaglia, Marina; Kontar, Eduard

    X-rays from solar flare sources are an important diagnostic tool for particle acceleration and transport in the solar atmosphere. However, the observed flux at Earth is composed of direct emission and photons which are Compton backscattered from the photosphere. This contribu-tion can account for up to 40 We present imaging observations of a compact flare on the solar disc. The source full-width-half maximum was determined at different energies using X-ray visibility forward fitting. The observed source size increases and decreases with energy with a maximum size at about 40 keV, contrary to observations made in limb events. The behavior is consistent with predictions from Monte Carlo simulations of X-ray photon transport in which X-ray visibilities were computed from simulated maps and fitted using visibility forward fit.

  18. Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) scientific objectives

    NASA Astrophysics Data System (ADS)

    Riese, M.; Oelhaf, H.; Preusse, P.; Blank, J.; Ern, M.; Friedl-Vallon, F.; Fischer, H.; Guggenmoser, T.; Höpfner, M.; Hoor, P.; Kaufmann, M.; Orphal, J.; Plöger, F.; Spang, R.; Suminska-Ebersoldt, O.; Ungermann, J.; Vogel, B.; Woiwode, W.

    2014-07-01

    The upper troposphere/lower stratosphere (UTLS) represents an important part of the climate system. Even small changes in the composition and dynamic structure of this region have significant radiative effects. Quantifying the underlying physical and chemical processes therefore represents a crucial task. Currently, there is a lack of UTLS observations with sufficient three-dimensional resolution. The Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) aircraft instrument addresses this observational lack by providing observations of numerous trace constituents as well as temperature and cloud structures with an unprecedented combination of vertical resolution (up to 300 m) and horizontal resolution (about 30 km × 30 km). As a result, important scientific questions concerning stratosphere-troposphere exchange, the occurrence of subvisible cirrus clouds in the lowermost stratosphere (LMS), polar chemistry, and gravity wave processes can be addressed, as reviewed in this paper.

  19. Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) scientific objectives

    NASA Astrophysics Data System (ADS)

    Riese, M.; Oelhaf, H.; Preusse, P.; Blank, J.; Ern, M.; Friedl-Vallon, F.; Fischer, H.; Guggenmoser, T.; Höpfner, M.; Hoor, P.; Kaufmann, M.; Orphal, J.; Plöger, F.; Spang, R.; Suminska-Ebersoldt, O.; Ungermann, J.; Vogel, B.; Woiwode, W.

    2014-02-01

    The upper troposphere/lower stratosphere (UTLS) plays a crucial role in the climate system. Changes in the composition and dynamic structure of this atmospheric region result in particularly large changes in the atmospheric radiation balance. Quantifying the physical and chemical processes that control UTLS composition therefore represents an important task. Currently, there is a lack of UTLS observations with sufficient three-dimensional resolution. The Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) aircraft instrument addresses this observational lack by providing observations of numerous trace constituents as well as temperature and cloud structures with an unprecedented combination of vertical resolution (up to 300 m) and horizontal resolution (up to 20 km × 20 km). As a result, important scientific questions concerning stratosphere-troposphere-exchange, the occurrence of subvisible cirrus clouds in the lowermost stratosphere (LMS), polar chemistry and gravity wave processes can be addressed, as reviewed in this paper.

  20. Gamma-ray burst observations with new generation imaging atmospheric Cerenkov Telescopes in the FERMI era

    SciTech Connect

    Covino, S.; Campana, S.; Galante, N.; Gaug, M.; Longo, F.; Scapin, V.

    2009-04-08

    After the launch and successful beginning of operations of the FERMI satellite, the topics related to high-energy observations of gamma-ray bursts have obtained a considerable attention by the scientific community. Undoubtedly, the diagnostic power of high-energy observations in constraining the emission processes and the physical conditions of gamma-ray burst is relevant. We briefly discuss how gamma-ray burst observations with ground-based imaging array Cerenkov telescopes, in the GeV-TeV range, can compete and cooperate with FERMI observations, in the MeV-GeV range, to allow researchers to obtain a more detailed and complete picture of the prompt and afterglow phases of gamma-ray bursts.

  1. Optimal strategies for observation of active galactic nuclei variability with Imaging Atmospheric Cherenkov Telescopes

    NASA Astrophysics Data System (ADS)

    Giomi, Matteo; Gerard, Lucie; Maier, Gernot

    2016-07-01

    Variable emission is one of the defining characteristic of active galactic nuclei (AGN). While providing precious information on the nature and physics of the sources, variability is often challenging to observe with time- and field-of-view-limited astronomical observatories such as Imaging Atmospheric Cherenkov Telescopes (IACTs). In this work, we address two questions relevant for the observation of sources characterized by AGN-like variability: what is the most time-efficient way to detect such sources, and what is the observational bias that can be introduced by the choice of the observing strategy when conducting blind surveys of the sky. Different observing strategies are evaluated using simulated light curves and realistic instrument response functions of the Cherenkov Telescope Array (CTA), a future gamma-ray observatory. We show that strategies that makes use of very small observing windows, spread over large periods of time, allows for a faster detection of the source, and are less influenced by the variability properties of the sources, as compared to strategies that concentrate the observing time in a small number of large observing windows. Although derived using CTA as an example, our conclusions are conceptually valid for any IACTs facility, and in general, to all observatories with small field of view and limited duty cycle.

  2. Initial Observations and Activities of Curiosity's Mars Hand Lens Imager (MAHLI) at the Gale Field Site

    NASA Astrophysics Data System (ADS)

    Aileen Yingst, R.; Edgett, Kenneth; MSL Science Team

    2013-04-01

    the dust and sand obscuration, the observables are unclear —grains 300-500 µm size in the Bathurst Inlet images and 300-500 µm-sized rhombus-shaped crystals in the rock, Jake Matijevic have been observed by some workers. Sand and granules (as well as dust), exhibiting a variety of colors, shapes, and other grain attributes, were deposited on rover hardware during descent. As noted above, sand as well as dust also mantles the rocks observed by MAHLI; in one case the cohesive properties of this material was demonstrated by the presence of a "micro landslide" on a rock named Burwash. At the Rocknest sand shadow, a variety of coarse to very coarse sand grains of differing color, shape, luster, angularity, and roundness were observed, including glassy spheroids and ellipsoids (perhaps formed from impact melt droplets) and clear, translucent grains. The fine to very fine sands sieved (≤ 150 µm) and delivered to the rover's observation tray exhibited at least four distinct grain types, including clear, translucent crystal fragments.

  3. The Anisotropy of the Microwave Background to l=3500: Mosaic Observations with the Cosmic Background Imager

    NASA Technical Reports Server (NTRS)

    Pearson, T. J.; Mason, B. S.; Readhead, A. C. S.; Shepherd, M. C.; Sievers, J. L.; Udomprasert, P. S.; Cartwright, J. K.; Farmer, A. J.; Padin, S.; Myers, S. T.; Six, N. Frank (Technical Monitor)

    2002-01-01

    Using the Cosmic Background Imager, a 13-element interferometer array operating in the 26-36 GHz frequency band, we have observed 40 deg (sup 2) of sky in three pairs of fields, each approximately 145 feet x 165 feet, using overlapping pointings: (mosaicing). We present images and power spectra of the cosmic microwave background radiation in these mosaic fields. We remove ground radiation and other low-level contaminating signals by differencing matched observations of the fields in each pair. The primary foreground contamination is due to point sources (radio galaxies and quasars). We have subtracted the strongest sources from the data using higher-resolution measurements, and we have projected out the response to other sources of known position in the power-spectrum analysis. The images show features on scales approximately 6 feet-15 feet, corresponding to masses approximately 5-80 x 10(exp 14) solar mass at the surface of last scattering, which are likely to be the seeds of clusters of galaxies. The power spectrum estimates have a resolution delta l approximately 200 and are consistent with earlier results in the multipole range l approximately less than 1000. The power spectrum is detected with high signal-to-noise ratio in the range 300 approximately less than l approximately less than 1700. For 1700 approximately less than l approximately less than 3000 the observations are consistent with the results from more sensitive CBI deep-field observations. The results agree with the extrapolation of cosmological models fitted to observations at lower l, and show the predicted drop at high l (the "damping tail").

  4. Probing the functions of contextual modulation by adapting images rather than observers

    PubMed Central

    Webster, Michael A.

    2014-01-01

    Countless visual aftereffects have illustrated how visual sensitivity and perception can be biased by adaptation to the recent temporal context. This contextual modulation has been proposed to serve a variety of functions, but the actual benefits of adaptation remain uncertain. We describe an approach we have recently developed for exploring these benefits by adapting images instead of observers, to simulate how images should appear under theoretically optimal states of adaptation. This allows the long-term consequences of adaptation to be evaluated in ways that are difficult to probe by adapting observers, and provides a common framework for understanding how visual coding changes when the environment or the observer changes, or for evaluating how the effects of temporal context depend on different models of visual coding or the adaptation processes. The approach is illustrated for the specific case of adaptation to color, for which the initial neural coding and adaptation processes are relatively well understood, but can in principle be applied to examine the consequences of adaptation for any stimulus dimension. A simple calibration that adjusts each neuron’s sensitivity according to the stimulus level it is exposed to is sufficient to normalize visual coding and generate a host of benefits, from increased efficiency to perceptual constancy to enhanced discrimination. This temporal normalization may also provide an important precursor for the effective operation of contextual mechanisms operating across space or feature dimensions. To the extent that the effects of adaptation can be predicted, images from new environments could be “pre-adapted” to match them to the observer, eliminating the need for observers to adapt. PMID:25281412

  5. Probing the functions of contextual modulation by adapting images rather than observers.

    PubMed

    Webster, Michael A

    2014-11-01

    Countless visual aftereffects have illustrated how visual sensitivity and perception can be biased by adaptation to the recent temporal context. This contextual modulation has been proposed to serve a variety of functions, but the actual benefits of adaptation remain uncertain. We describe an approach we have recently developed for exploring these benefits by adapting images instead of observers, to simulate how images should appear under theoretically optimal states of adaptation. This allows the long-term consequences of adaptation to be evaluated in ways that are difficult to probe by adapting observers, and provides a common framework for understanding how visual coding changes when the environment or the observer changes, or for evaluating how the effects of temporal context depend on different models of visual coding or the adaptation processes. The approach is illustrated for the specific case of adaptation to color, for which the initial neural coding and adaptation processes are relatively well understood, but can in principle be applied to examine the consequences of adaptation for any stimulus dimension. A simple calibration that adjusts each neuron's sensitivity according to the stimulus level it is exposed to is sufficient to normalize visual coding and generate a host of benefits, from increased efficiency to perceptual constancy to enhanced discrimination. This temporal normalization may also provide an important precursor for the effective operation of contextual mechanisms operating across space or feature dimensions. To the extent that the effects of adaptation can be predicted, images from new environments could be "pre-adapted" to match them to the observer, eliminating the need for observers to adapt. PMID:25281412

  6. Demonstration of imaging Fourier Transform Spectrometer (FTS) performance for planetary and geostationary Earth observing

    NASA Astrophysics Data System (ADS)

    Revercomb, Henry E.; Sromovsky, Lawrence A.; Fry, Patrick M.; Best, Fred A.; LaPorte, Daniel D.

    2001-02-01

    The combination of massively parallel spatial sampling and accurate spectral radiometry offered by imaging FTS makes it extremely attractive for earth and planetary remote sensing. We constructed a breadboard instrument to help assess the potential for planetary applications of small imaging FTS instruments in the 1-5 micrometers range. The results also support definition of the NASA Geostationary Imaging FTS instrument that will make key meteorological and climate observations from geostationary earth orbit. The PIFTS pivoting voice- coil delay scan mechanism, and laser diode metrology system. The interferometer optical output is measured by a commercial IR camera procured from Santa Barbara Focal plane. It uses an InSb 128 by 128 detector array that covers the entire FOV of the instrument when coupled with a 25-mm focal length commercial camera lens. With appropriate lenses and cold filters the instrument can be used from the visible to 5 micrometers . The delay scan is continuos, but slow, covering the maximum range of +/- 0.4 cm in 37.56 sec at a rate of 500 image frames per second. Image exposures are timed to be centered around predicted zero crossings. The design allows for prediction algorithms that account for the most recent fringe rate so that timing jitter produced by scan speed variations can be minimized. Response to a fixed source is linear with exposure time nearly to the point of saturation. Linearity with respect to input variations was demonstrated to within 0.16 percent using a 3-point blackbody calibration. Imaging of external complex scenes was carried out at low and high spectral resolution. These require full complex calibration to remove background contributions that vary dramatically over the instrument FOV. Testing is continuing to demonstrate the precise radiometric accuracy and noise characteristics.

  7. Gemini Planet Imager Observations of the AU Microscopii Debris Disk: Asymmetries within One Arcsecond

    NASA Astrophysics Data System (ADS)

    Wang, Jason J.; Graham, James R.; Pueyo, Laurent; Nielsen, Eric L.; Millar-Blanchaer, Max; De Rosa, Robert J.; Kalas, Paul; Ammons, S. Mark; Bulger, Joanna; Cardwell, Andrew; Chen, Christine; Chiang, Eugene; Chilcote, Jeffrey K.; Doyon, René; Draper, Zachary H.; Duchêne, Gaspard; Esposito, Thomas M.; Fitzgerald, Michael P.; Goodsell, Stephen J.; Greenbaum, Alexandra Z.; Hartung, Markus; Hibon, Pascale; Hinkley, Sasha; Hung, Li-Wei; Ingraham, Patrick; Larkin, James E.; Macintosh, Bruce; Maire, Jerome; Marchis, Franck; Marois, Christian; Matthews, Brenda C.; Morzinski, Katie M.; Oppenheimer, Rebecca; Patience, Jenny; Perrin, Marshall D.; Rajan, Abhijith; Rantakyrö, Fredrik T.; Sadakuni, Naru; Serio, Andrew; Sivaramakrishnan, Anand; Soummer, Rémi; Thomas, Sandrine; Ward-Duong, Kimberly; Wiktorowicz, Sloane J.; Wolff, Schuyler G.

    2015-10-01

    We present Gemini Planet Imager (GPI) observations of AU Microscopii, a young M dwarf with an edge-on, dusty debris disk. Integral field spectroscopy and broadband imaging polarimetry were obtained during the commissioning of GPI. In our broadband imaging polarimetry observations, we detect the disk only in total intensity and find asymmetries in the morphology of the disk between the southeast (SE) and northwest (NW) sides. The SE side of the disk exhibits a bump at 1″ (10 AU projected separation) that is three times more vertically extended and three times fainter in peak surface brightness than the NW side at similar separations. This part of the disk is also vertically offset by 69 ± 30 mas to the northeast at 1″ when compared to the established disk midplane and is consistent with prior Atacama Large Millimeter/submillimeter Array and Hubble Space Telescope/Space Telescope Imaging Spectrograph observations. We see hints that the SE bump might be a result of detecting a horizontal sliver feature above the main disk that could be the disk backside. Alternatively, when including the morphology of the NW side, where the disk midplane is offset in the opposite direction ∼50 mas between 0.″4 and 1.″2, the asymmetries suggest a warp-like feature. Using our integral field spectroscopy data to search for planets, we are 50% complete for ∼4 MJup planets at 4 AU. We detect a source, resolved only along the disk plane, that could either be a candidate planetary mass companion or a compact clump in the disk.

  8. On the Active Region Bright Grains Observed in the Transition Region Imaging Channels of IRIS

    NASA Astrophysics Data System (ADS)

    Skogsrud, H.; Rouppe van der Voort, L.; De Pontieu, B.

    2016-02-01

    The Interface Region Imaging Spectrograph (IRIS) provides spectroscopy and narrow band slit-jaw (SJI) imaging of the solar chromosphere and transition region at unprecedented spatial and temporal resolutions. Combined with high-resolution context spectral imaging of the photosphere and chromosphere as provided by the Swedish 1 m Solar Telescope (SST), we can now effectively trace dynamic phenomena through large parts of the solar atmosphere in both space and time. IRIS SJI 1400 images from active regions, which primarily sample the transition region with the Si iv 1394 and 1403 Å lines, reveal ubiquitous bright “grains” which are short-lived (two to five minute) bright roundish small patches of sizes 0.″5-1.″7 that generally move limbward with velocities up to about 30 km s-1. In this paper, we show that many bright grains are the result of chromospheric shocks impacting the transition region. These shocks are associated with dynamic fibrils (DFs), most commonly observed in Hα. We find that the grains show the strongest emission in the ascending phase of the DF, that the emission is strongest toward the top of the DF, and that the grains correspond to a blueshift and broadening of the Si iv lines. We note that the SJI 1400 grains can also be observed in the SJI 1330 channel which is dominated by C ii lines. Our observations show that a significant part of the active region transition region dynamics is driven from the chromosphere below rather than from coronal activity above. We conclude that the shocks that drive DFs also play an important role in the heating of the upper chromosphere and lower transition region.

  9. IMAGE Observations of Sounder Stimulated and Naturally Occurring Fast Z mode Cavity Noise

    NASA Astrophysics Data System (ADS)

    Sonwalkar, V. S.; Taylor, C.; Reddy, A.

    2015-12-01

    We report first observations of sounder stimulated and naturally occurring fast Z mode (ZM) cavity noise detected by the Radio Plasma Imager (RPI) on the IMAGE satellite. The fast Z mode cavity noise is a banded, structure-less radio emission trapped inside fast Z mode cavities, which are characterized by a minimum (fz,min) in fast Z mode cut-off frequency (fz) along a geomagnetic field line [Gurnett et al., JGR, 1983]. Fast Z mode waves reflect at fz ~ f, where f is the wave frequency. Waves in the frequency range fz,min < f < fz,max, where fz,max is the maximum fz above fz,min altitude, are trapped within the cavity as they bounce back and forth between reflection altitudes (fz ~ f) above and below the fz,min altitude. These trapped waves will be observed by a satellite passing through the cavity. The observed cavity noise lower cutoff is at the local Z mode cut-off frequency (fz,Sat) and the upper cut-off is presumably close to fz,max. The cavity noise is observed typically inside the plasmasphere. Comparison of cavity noise as observed on the plasmagram obtained during active sounding with that observed on the dynamic spectra obtained from the interspersed passive wave measurements indicate that the cavity noise is either stimulated by transmissions from the sounder (RPI) or is of natural origin. The sounder stimulated noise is often accompanied by fast Z mode echoes. The naturally occurring cavity noise is observed on both the plasmagram and the dynamic spectra. We believe the stimulated cavity noise is generated due to scattering from small-scale irregularities of waves transmitted by RPI. One potential candidate for the source of naturally occurring Z mode cavity noise is the ring current electrons that can generate fast ZM waves via higher order cyclotron resonance [Nishimura et al., Earth Planets Space, 2007].

  10. Detection of facilities in satellite imagery using semi-supervised image classification and auxiliary contextual observables

    SciTech Connect

    Harvey, Neal R; Ruggiero, Christy E; Pawley, Norma H; Brumby, Steven P; Macdonald, Brian; Balick, Lee; Oyer, Alden

    2009-01-01

    Detecting complex targets, such as facilities, in commercially available satellite imagery is a difficult problem that human analysts try to solve by applying world knowledge. Often there are known observables that can be extracted by pixel-level feature detectors that can assist in the facility detection process. Individually, each of these observables is not sufficient for an accurate and reliable detection, but in combination, these auxiliary observables may provide sufficient context for detection by a machine learning algorithm. We describe an approach for automatic detection of facilities that uses an automated feature extraction algorithm to extract auxiliary observables, and a semi-supervised assisted target recognition algorithm to then identify facilities of interest. We illustrate the approach using an example of finding schools in Quickbird image data of Albuquerque, New Mexico. We use Los Alamos National Laboratory's Genie Pro automated feature extraction algorithm to find a set of auxiliary features that should be useful in the search for schools, such as parking lots, large buildings, sports fields and residential areas and then combine these features using Genie Pro's assisted target recognition algorithm to learn a classifier that finds schools in the image data.

  11. Detection of facilities in satellite imagery using semi-supervized image classification and auxiliary contextual observables

    NASA Astrophysics Data System (ADS)

    Harvey, Neal R.; Ruggiero, C.; Pawley, N. H.; MacDonald, B.; Oyer, A.; Balick, L.; Brumby, S. P.

    2009-05-01

    Detecting complex targets, such as facilities, in commercially available satellite imagery is a difficult problem that human analysts try to solve by applying world knowledge. Often there are known observables that can be extracted by pixel-level feature detectors that can assist in the facility detection process. Individually, each of these observables is not sufficient for an accurate and reliable detection, but in combination, these auxiliary observables may provide sufficient context for detection by a machine learning algorithm. We describe an approach for automatic detection of facilities that uses an automated feature extraction algorithm to extract auxiliary observables, and a semi-supervised assisted target recognition algorithm to then identify facilities of interest. We illustrate the approach using an example of finding schools in Quickbird image data of Albuquerque, New Mexico. We use Los Alamos National Laboratory's Genie Pro automated feature extraction algorithm to find a set of auxiliary features that should be useful in the search for schools, such as parking lots, large buildings, sports fields and residential areas and then combine these features using Genie Pro's assisted target recognition algorithm to learn a classifier that finds schools in the image data.

  12. Low-altitude image striations associated with bottomside equatorial spread F: Observations and theory

    SciTech Connect

    Vickrey, J.F.; Kelley, M.C.; Pfaff, R.; Goldman, S.R.

    1984-05-01

    Ionspheric plasma instabilities are usually discussed in terms of local parameters. However, because electric fields of scale size lambda> or approx. =1 km map along magnetic field lines, plasma populations far away from a locally unstable region may be affected by the instability process and vice versa. We present observations of electron density variations in the F/sub 1/ region of the ionosphere at two locations near the magnetic equator. Oscillations in electron number density that were confined to a narrow wavelength regime were observed in a region of the ionosphere with a very weak vertical density gradient. Since magnetic flux tube interchange instabilities cannot create structure in such an environment we suggest that these are ''images'' of instabilities occurring elsewhere along the magnetic field line. A simple steady state theory of image formation is developed that is in good agreement with the observations. Moreover, this theory predicts a scale size dependent ''effective diffusion'' process in the F region that may dominate over classical cross-field diffusion at kilometer scale sizes. Such a scale size dependent diffusion process is required to explain recent scintillation observations of decaying equatorial plumes.

  13. Lunar absolute reflectance as observed by Chang'E-1 Imaging Interferometer

    NASA Astrophysics Data System (ADS)

    Zhang, Jiang; Ling, ZongCheng; Liu, JianZhong; Wu, ZhongChen; Li, Bo; Ni, YuHeng

    2015-08-01

    Lunar absolute reflectance, which describes the fraction of solar radiation reflected by the Moon, is fundamental for the Chang'E-1 Imaging Interferometer (IIM) to map lunar mineralogical and elemental distributions. Recent observations made by the Spectral Irradiance Monitor (SIM) onboard the Solar Radiation and Climate Experiment (SORCE) spacecraft indicate that temporal variation in the solar radiation might have non-negligible influence on reflectance calculation, and the SIM measurements are different from the two previously used solar irradiances, i.e., ATLAS3 and Newkur. To provide reliable science results, we examined solar irradiance variability with the SIM daily observations, derived lunar absolute reflectances from the IIM 2A radiance with the SIM, ATLAS3 and Newkur data, and compared them with the Chandrayaan-1 Moon Mineralogy Mapper (M3), the Robotic Lunar Observatory (ROLO) and the Kaguya Multispectral Imager (MI) results. The temporal variability of the SIM solar irradiance is 0.25%-1.1% in the IIM spectral range, and less than 0.2% during the IIM observations. Nevertheless, the differences between the SIM measurements and the ATLAS3 and Newkur data can respectively rise up to 8% and 5% at particular IIM bands, resulting in discrepancy between which might affect compositional mapping. The IIM absolute reflectance we derived for the Moon using the SIM data, except for the last two bands, is consistent with the ROLO and the MI observations, although it is lower.

  14. HIRIS - NASAS's High-Resolution Imaging Spectrometer for the Earth Observing System

    NASA Technical Reports Server (NTRS)

    Dozier, J.

    1992-01-01

    Modern Earth science is beginning to examine interactions among the different terrestrial components at all temporal and spatial scales. Such a global perspective requires an integrated remote-sensing program, the Earth Observing System (EOS), which uses instruments throughout the electromagnetic spectrum to collect data about the Earth's surface, oceans and atmosphere over a range of selected scales. At the finest scales, we will require instruments capable of detailed sampling both spatially and spectrally. We have designed the High-Resoulution Imaging Spectrometer (HIRIS) to acquire simultaneous images in 192 spectral bands in the dominant wavelengths of the solar spectrum, 0.4 to 2.5 micrometers, at a spectral sampling interval of 10 nm. The ground instantaneous field of view (GIFOV) will be 30 m over a 24 km swath. A pointing capability will allow image acquisition up to +52 deg/-30 deg down track and +/-45 deg or more cross-track. Thus we will be able to study surface spectral bidirectional reflectance properties and variations in atmospheric attenuation with viewing angle. The cross-track pointing will also allow multiple viewing opportunities during one 16-day orbital revisit cycle, so that any part of the Earth may be imaged in a two-day period.

  15. Functional magnetic resonance imaging in intact plants--quantitative observation of flow in plant vessels.

    PubMed

    Kuchenbrod, E; Kahler, E; Thürmer, F; Deichmann, R; Zimmermann, U; Haase, A

    1998-04-01

    Quantitative magnetic resonance (MR) images of flow velocities in intact corn plants were acquired using magnetization-prepared MR microscopy. A phase contrast flow imaging technique was used to quantitate water flow velocities and total volume flow rates in small xylem vessels. The simultaneous measurement of the transpiration of the whole plant was achieved by using a closed climate chamber within the MR magnet. The total volume flow rate and the transpiration values were in close correlation. Functional magnetic resonance imaging in intact plants was performed by light stimulation of the transpiration inside of the magnet. The change in the flow velocities in the xylem vessels of single vascular bundles was in correlation with the changes in the transpiration. Significant differences were observed between the xylem vessels in different vascular bundles. Furthermore, flow velocity measurements were performed on excised plant stems and visualized by the uptake of the MR contrast agent, gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA). A comparison between the phase contrast flow imaging and the contrast media uptake showed to be in good agreement with each other. PMID:9621974

  16. VLBI observations of the gravitational lens system 0957+561 - Structure and relative magnification of the A and B images

    NASA Technical Reports Server (NTRS)

    Gorenstein, M. V.; Shapiro, I. I.; Bonometti, R. J.; Cohen, N. L.; Rogers, A. E. E.

    1988-01-01

    Gravitationally lensed images of the quasar 0957+561 have been observed at 13 cm wavelength using a six-antenna VLBI array with nearly milliarcsecond resolution. Models of the observed surface brightness distribution of each of the A and B images provide support of the gravitational lens hypothesis. A value of the magnitude of the relative image magnification A/B of 0.64 + or - 0.03 is obtained.

  17. Solar corona synoptic observations from SOHO with an extreme ultraviolet imaging telescope

    NASA Technical Reports Server (NTRS)

    Delaboudiniere, Jean-Pierre; Gabriel, A. H.; Artzner, G. E.; Dere, Ken; Howard, Russell A.; Michels, D.; Catura, Richard; Lemen, J.; Stern, R.; Gurman, Joseph B.

    1992-01-01

    The major scientific objective of the EUV Imaging Telescope (EIT) is to study the evolution of coronal structure over a wide range of spatial and temporal scales and temperatures. A second strategic objective is to provide full disk synoptic maps of the global corona to aid in unifying SOHO (Solar and Heliospheric Observatory)/Cluster investigations. EIT will also provide images to support the planning of detailed spectroscopic investigations by the CDS (Coronal Diagnostic Spectrometer) and SUMER spectrometers in SOHO. EIT observations will be made in four narrow spectral bands, centered at 171 A (Fe 9), 195 A(Fe 12), 284 A (Fe 15), and 304 A (He 2) representing restricted temperature domains within a wide temperature range from 40,000 to 3,000,000 K. The results will be images of the solar atmosphere from the upper chromosphere and transition region to the active region corona. These maps, made at appropriate time intervals, will be used to study the fine structures in the solar corona and to relate their dynamic properties to the underlying chromosphere and photosphere. Dynamic events in the inner corona will be related to white light transients in the outer corona, and observations of the internal structure of coronal holes will be used to investigate origins of the solar wind.

  18. A Decameter Stationary Type IV Burst in Imaging Observations on 2014 September 6

    NASA Astrophysics Data System (ADS)

    Koval, Artem; Stanislavsky, Aleksander; Chen, Yao; Feng, Shiwei; Konovalenko, Aleksander; Volvach, Yaroslav

    2016-08-01

    First-of-its-kind radio imaging of a decameter solar stationary type IV radio burst has been presented in this paper. On 2014 September 6 the observations of type IV burst radio emission were carried out with the two-dimensional heliograph based on the Ukrainian T-shaped radio telescope (UTR-2), together with other telescope arrays. Starting at ˜09:55 UT and for ˜3 hr, the radio emission was kept within the observational session of UTR-2. The interesting observation covered the full evolution of this burst, “from birth to death.” During the event lifetime, two C-class solar X-ray flares with peak times 11:29 UT and 12:24 UT took place. The time profile of this burst in radio has a double-humped shape that can be explained by injection of energetic electrons, accelerated by the two flares, into the burst source. According to the heliographic observations, we suggest that the burst source was confined within a high coronal loop, which was part of a relatively slow coronal mass ejection. The latter has been developed for several hours before the onset of the event. Through analysis of about 1.5 × 106 heliograms (3700 temporal frames with 4096 images in each frame that correspond to the number of frequency channels), the radio burst source imaging shows a fascinating dynamical evolution. Both space-based (GOES, SDO, SOHO, STEREO) data and various ground-based instrumentation (ORFEES, NDA, RSTO, NRH) records have been used for this study.

  19. A Decameter Stationary Type IV Burst in Imaging Observations on 2014 September 6

    NASA Astrophysics Data System (ADS)

    Koval, Artem; Stanislavsky, Aleksander; Chen, Yao; Feng, Shiwei; Konovalenko, Aleksander; Volvach, Yaroslav

    2016-08-01

    First-of-its-kind radio imaging of a decameter solar stationary type IV radio burst has been presented in this paper. On 2014 September 6 the observations of type IV burst radio emission were carried out with the two-dimensional heliograph based on the Ukrainian T-shaped radio telescope (UTR-2), together with other telescope arrays. Starting at ∼09:55 UT and for ∼3 hr, the radio emission was kept within the observational session of UTR-2. The interesting observation covered the full evolution of this burst, “from birth to death.” During the event lifetime, two C-class solar X-ray flares with peak times 11:29 UT and 12:24 UT took place. The time profile of this burst in radio has a double-humped shape that can be explained by injection of energetic electrons, accelerated by the two flares, into the burst source. According to the heliographic observations, we suggest that the burst source was confined within a high coronal loop, which was part of a relatively slow coronal mass ejection. The latter has been developed for several hours before the onset of the event. Through analysis of about 1.5 × 106 heliograms (3700 temporal frames with 4096 images in each frame that correspond to the number of frequency channels), the radio burst source imaging shows a fascinating dynamical evolution. Both space-based (GOES, SDO, SOHO, STEREO) data and various ground-based instrumentation (ORFEES, NDA, RSTO, NRH) records have been used for this study.

  20. Comparison of HRDI wind measurements with radar and rocket observations. [High Resolution Doppler Imager

    NASA Technical Reports Server (NTRS)

    Burrage, M. D.; Skinner, W. R.; Marshall, A. R.; Hays, P. B.; Lieberman, R. S.; Franke, S. J.; Gell, D. A.; Ortland, D. A.; Morton, Y. T.; Schmidlin, F. J.

    1993-01-01

    Wind fields in the mesosphere and lower thermosphere are obtained with the High Resolution Doppler Imager (HRDI) on the Upper Atmosphere Research Satellite (UARS) by observing the Doppler shifts of emission lines in the O2 Atmospheric band. The validity of the measured winds depends on an accurate knowledge of the positions on the detector of the observed lines in the absence of a wind-induced Doppler shift. These positions have been determined to an accuracy of approximately 5 m/s from the comparison of winds measured by HRDI with those obtained by MF radars. Excellent agreement is found between HRDI measured winds and winds observed with radars and rockets. In addition, the sensitivity of HRDI to migrating tides and other large scale waves is demonstrated.

  1. MAPIR: An Airborne Polarmetric Imaging Radiometer in Support of Hydrologic Satellite Observations

    NASA Technical Reports Server (NTRS)

    Laymon, C.; Al-Hamdan, M.; Crosson, W.; Limaye, A.; McCracken, J.; Meyer, P.; Richeson, J.; Sims, W.; Srinivasan, K.; Varnevas, K.

    2010-01-01

    In this age of dwindling water resources and increasing demands, accurate estimation of water balance components at every scale is more critical to end users than ever before. Several near-term Earth science satellite missions are aimed at global hydrologic observations. The Marshall Airborne Polarimetric Imaging Radiometer (MAPIR) is a dual beam, dual angle polarimetric, scanning L band passive microwave radiometer system developed by the Observing Microwave Emissions for Geophysical Applications (OMEGA) team at MSFC to support algorithm development and validation efforts in support of these missions. MAPIR observes naturally-emitted radiation from the ground primarily for remote sensing of land surface brightness temperature from which we can retrieve soil moisture and possibly surface or water temperature and ocean salinity. MAPIR has achieved Technical Readiness Level 6 with flight heritage on two very different aircraft, the NASA P-3B, and a Piper Navajo.

  2. In vivo observation of tree drought response with low-field NMR and neutron imaging

    DOE PAGESBeta

    Malone, Michael W.; Yoder, Jacob; Hunter, James F.; Espy, Michelle A.; Dickman, Lee T.; Nelson, Ron O.; Vogel, Sven C.; Sandin, Henrik J.; Sevanto, Sanna

    2016-05-01

    Using a simple low-field NMR system, we monitored water content in a living tree in a greenhouse over 2 months. By continuously running the system, we observed changes in tree water content on a scale of half an hour. The data showed a diurnal change in water content consistent both with previous NMR and biological observations. Neutron imaging experiments show that our NMR signal is primarily due to water being rapidly transported through the plant, and not to other sources of hydrogen, such as water in cytoplasm, or water in cell walls. After accounting for the role of temperature inmore » the observed NMR signal, we demonstrate a change in the diurnal signal behavior due to simulated drought conditions for the tree. Lastly, these results illustrate the utility of our system to perform noninvasive measurements of tree water content outside of a temperature controlled environment.« less

  3. In vivo Observation of Tree Drought Response with Low-Field NMR and Neutron Imaging

    PubMed Central

    Malone, Michael W.; Yoder, Jacob; Hunter, James F.; Espy, Michelle A.; Dickman, Lee T.; Nelson, Ron O.; Vogel, Sven C.; Sandin, Henrik J.; Sevanto, Sanna

    2016-01-01

    Using a simple low-field NMR system, we monitored water content in a living tree in a greenhouse over 2 months. By continuously running the system, we observed changes in tree water content on a scale of half an hour. The data showed a diurnal change in water content consistent both with previous NMR and biological observations. Neutron imaging experiments show that our NMR signal is primarily due to water being rapidly transported through the plant, and not to other sources of hydrogen, such as water in cytoplasm, or water in cell walls. After accounting for the role of temperature in the observed NMR signal, we demonstrate a change in the diurnal signal behavior due to simulated drought conditions for the tree. These results illustrate the utility of our system to perform noninvasive measurements of tree water content outside of a temperature controlled environment. PMID:27200037

  4. First light observations with TIFR Near Infrared Imaging Camera (TIRCAM-II)

    NASA Astrophysics Data System (ADS)

    Ojha, D. K.; Ghosh, S. K.; D'Costa, S. L. A.; Naik, M. B.; Sandimani, P. R.; Poojary, S. S.; Bhagat, S. B.; Jadhav, R. B.; Meshram, G. S.; Bakalkar, C. B.; Ramaprakash, A. N.; Mohan, V.; Joshi, J.

    TIFR near infrared imaging camera (TIRCAM-II) is based on the Aladdin III Quadrant InSb focal plane array (512×512 pixels; 27.6 μm pixel size; sensitive between 1 - 5.5 μm). TIRCAM-II had its first engineering run with the 2 m IUCAA telescope at Girawali during February - March 2011. The first light observations with TIRCAM-II were quite successful. Several infrared standard with TIRCAM-II were quite successful. Several infrared standard stars, the Trapezium Cluster in Orion region, McNeil's nebula, etc., were observed in the J, K and in a narrow-band at 3.6 μm (nbL). In the nbL band, some bright stars could be detected from the Girawali site. The performance of TIRCAM-II is discussed in the light of preliminary observations in near infrared bands.

  5. In vivo Observation of Tree Drought Response with Low-Field NMR and Neutron Imaging.

    PubMed

    Malone, Michael W; Yoder, Jacob; Hunter, James F; Espy, Michelle A; Dickman, Lee T; Nelson, Ron O; Vogel, Sven C; Sandin, Henrik J; Sevanto, Sanna

    2016-01-01

    Using a simple low-field NMR system, we monitored water content in a living tree in a greenhouse over 2 months. By continuously running the system, we observed changes in tree water content on a scale of half an hour. The data showed a diurnal change in water content consistent both with previous NMR and biological observations. Neutron imaging experiments show that our NMR signal is primarily due to water being rapidly transported through the plant, and not to other sources of hydrogen, such as water in cytoplasm, or water in cell walls. After accounting for the role of temperature in the observed NMR signal, we demonstrate a change in the diurnal signal behavior due to simulated drought conditions for the tree. These results illustrate the utility of our system to perform noninvasive measurements of tree water content outside of a temperature controlled environment. PMID:27200037

  6. Comparison of model and human observer performance for detection and discrimination tasks using dual-energy x-ray images.

    PubMed

    Richard, Samuel; Siewerdsen, Jeffrey H

    2008-11-01

    Model observer performance, computed theoretically using cascaded systems analysis (CSA), was compared to the performance of human observers in detection and discrimination tasks. Dual-energy (DE) imaging provided a wide range of acquisition and decomposition parameters for which observer performance could be predicted and measured. This work combined previously derived observer models (e.g., Fisher-Hotelling and non-prewhitening) with CSA modeling of the DE image noise-equivalent quanta (NEQ) and imaging task (e.g., sphere detection, shape discrimination, and texture discrimination) to yield theoretical predictions of detectability index (d') and area under the receiver operating characteristic (Az). Theoretical predictions were compared to human observer performance assessed using 9-alternative forced-choice tests to yield measurement of Az as a function of DE image acquisition parameters (viz., allocation of dose between the low- and high-energy images) and decomposition technique [viz., three DE image decomposition algorithms: standard log subtraction (SLS), simple-smoothing of the high-energy image (SSH), and anti-correlated noise reduction (ACNR)]. Results showed good agreement between theory and measurements over a broad range of imaging conditions. The incorporation of an eye filter and internal noise in the observer models demonstrated improved correspondence with human observer performance. Optimal acquisition and decomposition parameters were shown to depend on the imaging task; for example, ACNR and SSH yielded the greatest performance in the detection of soft-tissue and bony lesions, respectively. This study provides encouraging evidence that Fourier-based modeling of NEQ computed via CSA and imaging task provides a good approximation to human observer performance for simple imaging tasks, helping to bridge the gap between Fourier metrics of detector performance (e.g., NEQ) and human observer performance. PMID:19070238

  7. Comparison of model and human observer performance for detection and discrimination tasks using dual-energy x-ray images

    SciTech Connect

    Richard, Samuel; Siewerdsen, Jeffrey H.

    2008-11-15

    Model observer performance, computed theoretically using cascaded systems analysis (CSA), was compared to the performance of human observers in detection and discrimination tasks. Dual-energy (DE) imaging provided a wide range of acquisition and decomposition parameters for which observer performance could be predicted and measured. This work combined previously derived observer models (e.g., Fisher-Hotelling and non-prewhitening) with CSA modeling of the DE image noise-equivalent quanta (NEQ) and imaging task (e.g., sphere detection, shape discrimination, and texture discrimination) to yield theoretical predictions of detectability index (d{sup '}) and area under the receiver operating characteristic (A{sub Z}). Theoretical predictions were compared to human observer performance assessed using 9-alternative forced-choice tests to yield measurement of A{sub Z} as a function of DE image acquisition parameters (viz., allocation of dose between the low- and high-energy images) and decomposition technique [viz., three DE image decomposition algorithms: standard log subtraction (SLS), simple-smoothing of the high-energy image (SSH), and anti-correlated noise reduction (ACNR)]. Results showed good agreement between theory and measurements over a broad range of imaging conditions. The incorporation of an eye filter and internal noise in the observer models demonstrated improved correspondence with human observer performance. Optimal acquisition and decomposition parameters were shown to depend on the imaging task; for example, ACNR and SSH yielded the greatest performance in the detection of soft-tissue and bony lesions, respectively. This study provides encouraging evidence that Fourier-based modeling of NEQ computed via CSA and imaging task provides a good approximation to human observer performance for simple imaging tasks, helping to bridge the gap between Fourier metrics of detector performance (e.g., NEQ) and human observer performance.

  8. Observables Processing for the Helioseismic and Magnetic Imager Instrument on the Solar Dynamics Observatory

    NASA Astrophysics Data System (ADS)

    Couvidat, S.; Schou, J.; Hoeksema, J. T.; Bogart, R. S.; Bush, R. I.; Duvall, T. L.; Liu, Y.; Norton, A. A.; Scherrer, P. H.

    2016-08-01

    NASA's Solar Dynamics Observatory (SDO) spacecraft was launched 11 February 2010 with three instruments onboard, including the Helioseismic and Magnetic Imager (HMI). After commissioning, HMI began normal operations on 1 May 2010 and has subsequently observed the Sun's entire visible disk almost continuously. HMI collects sequences of polarized filtergrams taken at a fixed cadence with two 4096 × 4096 cameras, from which are computed arcsecond-resolution maps of photospheric observables that include line-of-sight velocity and magnetic field, continuum intensity, line width, line depth, and the Stokes polarization parameters [ I, Q, U, V]. Two processing pipelines have been implemented at the SDO Joint Science Operations Center (JSOC) at Stanford University to compute these observables from calibrated Level-1 filtergrams, one that computes line-of-sight quantities every 45 seconds and the other, primarily for the vector magnetic field, that computes averages on a 720-second cadence. Corrections are made for static and temporally changing CCD characteristics, bad pixels, image alignment and distortion, polarization irregularities, filter-element uncertainty and nonuniformity, as well as Sun-spacecraft velocity. We detail the functioning of these two pipelines, explain known issues affecting the measurements of the resulting physical quantities, and describe how regular updates to the instrument calibration impact them. We also describe how the scheme for computing the observables is optimized for actual HMI observations. Initial calibration of HMI was performed on the ground using a variety of light sources and calibration sequences. During the five years of the SDO prime mission, regular calibration sequences have been taken on orbit to improve and regularly update the instrument calibration, and to monitor changes in the HMI instrument. This has resulted in several changes in the observables processing that are detailed here. The instrument more than satisfies all

  9. Observables Processing for the Helioseismic and Magnetic Imager Instrument on the Solar Dynamics Observatory

    NASA Astrophysics Data System (ADS)

    Couvidat, S.; Schou, J.; Hoeksema, J. T.; Bogart, R. S.; Bush, R. I.; Duvall, T. L.; Liu, Y.; Norton, A. A.; Scherrer, P. H.

    2016-08-01

    NASA's Solar Dynamics Observatory (SDO) spacecraft was launched 11 February 2010 with three instruments onboard, including the Helioseismic and Magnetic Imager (HMI). After commissioning, HMI began normal operations on 1 May 2010 and has subsequently observed the Sun's entire visible disk almost continuously. HMI collects sequences of polarized filtergrams taken at a fixed cadence with two 4096 × 4096 cameras, from which are computed arcsecond-resolution maps of photospheric observables that include line-of-sight velocity and magnetic field, continuum intensity, line width, line depth, and the Stokes polarization parameters [I, Q, U, V]. Two processing pipelines have been implemented at the SDO Joint Science Operations Center (JSOC) at Stanford University to compute these observables from calibrated Level-1 filtergrams, one that computes line-of-sight quantities every 45 seconds and the other, primarily for the vector magnetic field, that computes averages on a 720-second cadence. Corrections are made for static and temporally changing CCD characteristics, bad pixels, image alignment and distortion, polarization irregularities, filter-element uncertainty and nonuniformity, as well as Sun-spacecraft velocity. We detail the functioning of these two pipelines, explain known issues affecting the measurements of the resulting physical quantities, and describe how regular updates to the instrument calibration impact them. We also describe how the scheme for computing the observables is optimized for actual HMI observations. Initial calibration of HMI was performed on the ground using a variety of light sources and calibration sequences. During the five years of the SDO prime mission, regular calibration sequences have been taken on orbit to improve and regularly update the instrument calibration, and to monitor changes in the HMI instrument. This has resulted in several changes in the observables processing that are detailed here. The instrument more than satisfies all

  10. "Observing and Analyzing" Images from a Simulated High-Redshift Universe

    NASA Astrophysics Data System (ADS)

    Morgan, Robert J.; Windhorst, Rogier A.; Scannapieco, Evan; Thacker, Robert J.

    2015-09-01

    We investigate the high-redshift evolution of the rest-frame UV-luminosity function (LF) of galaxies via hydrodynamical cosmological simulations, coupled with an emulated observational astronomy pipeline that provides a direct comparison with observations. We do this by creating mock images and synthetic galaxy catalogs of ≈100 arcmin-2 fields from the numerical model at redshifts ≈4.5 to 10.4. We include the effects of dust extinction and the point-spread function (PSF) for the Hubble WFC3 camera for comparison with space observations. We also include the expected zodiacal background to predict its effect on space observations, including future missions such as the James Webb Space Telescope (JWST). When our model catalogs are fitted to Schechter function parameters, we predict that the faint-end slope (α) of the LF evolves as α = -1.16-0.12z over the redshift range z ≈ 4.5-7.7, in excellent agreement with observations from, e.g., Hathi and coworkers. However, for redshifts z ≈ 6-10.4, α(z) appears to display a shallower evolution, α = -1.79-0.03z. Augmenting the simulations with more detailed physics—specifically stellar winds and supernovae (SN)—produces similar results. The model shows an overproduction of galaxies, especially at faint magnitudes, compared with the observations, although the discrepancy is reduced when dust extinction is taken into account.

  11. Initial lunar calibration observations by the EO-1 Hyperion imaging spectrometer

    USGS Publications Warehouse

    Kieffer, H.H.; Jarecke, P.; Pearlman, Jay

    2002-01-01

    The Moon provides an exo-atmospheric radiance source that can be used to determine trends in instrument radio-metric responsivity with high precision. Lunar observations can also be used for absolute radiometric calibration; knowledge of the radiometric scale will steadily improve through independent study of lunar spectral photometry and with sharing of the Moon as a calibration target by increasing numbers of spacecraft, each with its own calibration history. EO-1 calibration includes periodic observation of the Moon by all three of its instruments. Observations are normally made with a phase angle of about 7 degrees (or about 12 hours from the time of Full Moon). Also, SeaWiFS has been making observations at such phase angles for several years, and observations of the Moon by instrument pairs, even if at different times, can be used to transfer absolute calibration. A challenge for EO-1 is pointing to include the entire full Moon in the narrow Hyperion scan. Three Hyperion observations in early 2001 covering an order-of-magnitude difference in lunar irradiance show good agreement for responsivity; the SWIR detector has undergone some changes in responsivity. Small discrepancies of calibration with wavelength could be smoothed using the Moon as a source. Off-axis scattered light response and cross-track response variations can be assessed using the lunar image.

  12. Simulated lesion, human observer performance comparison between thin-section dedicated breast CT images versus computed thick-section simulated projection images of the breast

    PubMed Central

    Chen, L; Boone, JM; Abbey, CK; Hargreaves, J; Bateni, C; Lindfors, KK; Yang, K; Nosratieh, A; Hernandez, A; Gazi, P

    2015-01-01

    Objectives The objective of this study was to compare the lesion detection performance of human observers between thin-section computed tomography images of the breast, with thick-section (>40 mm) simulated projection images of the breast. Methods Three radiologists and six physicists each executed a two alterative force choice (2AFC) study involving simulated spherical lesions placed mathematically into breast images produced on a prototype dedicated breast CT scanner. The breast image data sets from 88 patients were used to create 352 pairs of image data. Spherical lesions with diameters of 1, 2, 3, 5, and 11 mm were simulated and adaptively positioned into 3D breast CT image data sets; the native thin section (0.33 mm) images were averaged to produce images with different slice thicknesses; average section thicknesses of 0.33 mm, 0.71 mm, 1.5 mm, and 2.9 mm were representative of breast CT; the average 43 mm slice thickness served to simulate simulated projection images of the breast. Results The percent correct of the human observer’s responses were evaluated in the 2AFC experiments. Radiologists lesion detection performance was significantly (p<0.05) better in the case of thin-section images, compared to thick section images similar to mammography, for all but the 1 mm lesion diameter lesions. For example, the average of three radiologist’s performance for 3 mm diameter lesions was 92 % correct for thin section breast CT images while it was 67 % for the simulated projection images. A gradual reduction in observer performance was observed as the section thickness increased beyond about 1 mm. While a performance difference based on breast density was seen in both breast CT and the projection image results, the average radiologist performance using breast CT images in dense breasts outperformed the performance using simulated projection images in fatty breasts for all lesion diameters except 11 mm. The average radiologist performance outperformed that of the

  13. Water Uptake by Dry Beans Observed by Micro-magnetic Resonance Imaging

    PubMed Central

    KIKUCHI, KAORI; KOIZUMI, MIKA; ISHIDA, NOBUAKI; KANO, HIROMI

    2006-01-01

    • Background and Aims Water uptake by dry kidney beans (Phaseolus vulgaris ‘Rajma’) and adzuki beans (Vigna angularis) was traced using micro-magnetic resonance imaging in order to elucidate the channel of water entry, the manner of water delivery and the timing of swelling of the seeds. • Methods Magnetic resonance images of beans absorbing water were continuously measured with the single-point imaging method for 16 h or 20 h at 15-min intervals. With this technique, it was possible to detect and visualize the location of water in the beans, at a low water content, in the initial stages of water entry. • Key Results Water was taken up through a specified tissue, the lens, near the hilum, and distributed primarily to the testa. When water reached the radicle, it began to be incorporated into cotyledons with considerable swelling of the seeds. Water uptake took place within a short time for kidney beans. The initial process of water entry was associated with mechanical vibration of the seed. Rapid hydration of the testa and the swelling of the cotyledons were then observed. Water was supplied to cotyledons through the adaxial epidermis. In contrast, it took a long time, approx. 7 h, to activate the water channel of the lens for adzuki beans which have a tightly fitting testa. Steeping of the testa was not uniform, which induced temporary slanting before enlargement of the seed. • Conclusions The activation of the lens as the sole water channel, the delivery of water to the radicle within the testa, the swelling of the cotyledons, and the further increment of water are physiologically different processes during imbibition, and were separated by locating water in various tissues and by analysing the time course of water uptake using magnetic resonance imaging with the single-point imaging method. PMID:16845137

  14. Computed tomography and magnetic resonance imaging observations of rhabdomyosarcoma in the head and neck

    PubMed Central

    ZHU, JINGQI; ZHANG, JIANHUA; TANG, GUANGYU; HU, SHIYOU; ZHOU, GUOXING; LIU, YONGKANG; DAI, LINGLING; WANG, ZHONGQIU

    2014-01-01

    Head and neck (HN) rhabdomyosarcoma (RMS) is an aggressive malignancy, which is rarely encountered and is commonly misdiagnosed as another type of tumor. The aim of the present study was to investigate the computed tomography (CT) and magnetic resonance imaging (MRI) features of HNRMS and analyze the correlations between the imaging observations and the pathological subtypes. A total of 10 HNRMS patients (three males and seven females; median age, 16 years) were reviewed retrospectively by only CT (n=1), only MRI (n=2), as well as CT and MRI (n=7). In addition, the clinical data, imaging observations and pathological results were recorded and analyzed. The origins of the 10 HNRMSs (eight embryonal and two alveolar subtypes) included the ethmoid sinus (n=4), maxillary sinus (n=1), orbit (n=3), nasopharynx (n=1) and frontotemporal subcutaneous area (n=1). On the CT and MRI images, the soft-tissue masses exhibited ill-defined borders (n=9), bony destruction (n=10), multi-cavity growth (n=7) and cervical lymph node metastasis (n=2), whereas calcification and hemorrhaging were not identified. On CT, eight of the HNRMSs appeared slightly hypodense (2/8) or isodense (6/8) with homogeneous enhancement (4/4). On T1-weighted images (WI), nine tumors exhibited isointensity (9/9) and on T2WI, six tumors demonstrated homogeneous hyperintensity with homogeneous enhancement on contrast-enhanced (CE)-T1WI. In addition, three embryonal RMSs, which originated from the ethmoid sinus, exhibited heterogeneous hyperintensity on T2WI and nodule-shaped enhancement patterns on CE-T1WI. The results of the present study indicated that MRI may accurately demonstrate the location and extent of HNRMS and that the imaging features of HNRMS may be similar to those of other tumors. However, a tumor exhibiting heterogeneous hyperintensity on T2WI and a nodule-shaped enhancement pattern on CE-T1WI in the ethmoid sinus may present specific MRI features, which clearly indicates the botryoid subtype of

  15. Two Types of Aurora on Mars as Observed by MAVEN's Imaging UltraViolet Spectrograph

    NASA Astrophysics Data System (ADS)

    Schneider, N. M.; Deighan, J.; Jain, S.; Stiepen, A.; Stewart, I. F.; Larson, D. E.; Mitchell, D. L.; Mazelle, C. X.; Lee, C.; Lillis, R. J.; Evans, J. S.; Brain, D. A.; Stevens, M. H.; McClintock, W. E.; Chaffin, M.; Crismani, M. M. J.; Holsclaw, G. M.; Lefèvre, F.; Lo, D.; Clarke, J. T.; Montmessin, F.; Jakosky, B. M.

    2015-12-01

    The Imaging UltraViolet Spectrograph (IUVS) on the MAVEN spacecraft has detected two distinct types of auroral emission on Mars. First, we report the discovery of a low altitude, diffuse aurora spanning much of Mars' northern hemisphere coincident with a solar energetic particle outburst. IUVS observed northerly latitudes during late December 2014, detecting auroral emission in virtually all nightside observations for ~5 days spanning virtually all geographic longitudes. The vertical profile showed emission down to ~70 km altitude (1 microbar), deeper than confirmed at any other planet. The onset and duration of emission coincide with the observed arrival of solar energetic particles up to 200 keV precipitating directly and deeply into the atmosphere. Preliminary modeling of the precipitation, energy deposition and spectral line emission yields good matches to the observations. These observations represent a new class of planetary auroras produced in the Martian middle atmosphere. Given minimal magnetic fields over most of the planet, Mars is likely to exhibit aurora more globally than Earth. Second, we confirm the existence of small patches of discrete aurora near crustal magnetic fields in Mars' southern hemisphere, as observed previously by SPICAM on Mars Express (Bertaux et al., Nature, 435, 790-794 (2005)). IUVS observed southern latitudes in July and August 2015, detecting discrete auroral emission in ~1% of suitable observations. Limb scans resolved both vertically and along-slit indicate this type of auroral emission was patchy on the scale of ~40 km, and located at higher altitudes ~140 km. The higher altitudes imply a lower energy of precipitating particles. The mix of spectral emissions also differed signficiantly from the discrete aurora, indicating different excitation and quenching processes. We will discuss the observed properties of the aurora and associated charged particle precipitation, as well as the broader implications of this high

  16. Two Types of Aurora on Mars as Observed by MAVEN's Imaging UltraViolet Spectrograph

    NASA Astrophysics Data System (ADS)

    Schneider, Nicholas M.; Deighan, J.; Jain, S. K.; Stiepen, A.; Larson, D.; Mitchell, D. L.; Lee, C. O.; Lillis, R.; Brain, D.; McClintock, W. E.; Chaffin, M. S.; Crismani, M.; Holsclaw, G. M.; Jakosky, B. M.; Mazelle, C.; Evans, J. S.; Stewart, A. I. F.; Stevens, M. H.; Clarke, J. T.; Montmessin, F.; Lefevre, F.; Lo, D.

    2015-11-01

    The Imaging UltraViolet Spectrograph (IUVS) on the MAVEN spacecraft has detected two distinct types of auroral emission on Mars. First, we report the discovery of a low altitude, diffuse aurora spanning much of Mars’ northern hemisphere coincident with a solar energetic particle outburst. IUVS observed northerly latitudes during late December 2014, detecting auroral emission in virtually all nightside observations for ~5 days spanning virtually all geographic longitudes. The vertical profile showed emission down to ~70 km altitude (1 microbar), deeper than confirmed at any other planet. The onset and duration of emission coincide with the observed arrival of solar energetic particles up to 200 keV precipitating directly and deeply into the atmosphere. Preliminary modeling of the precipitation, energy deposition and spectral line emission yields good matches to the observations. These observations represent a new class of planetary auroras produced in the Martian middle atmosphere. Given minimal magnetic fields over most of the planet, Mars is likely to exhibit aurora more globally than Earth.Second, we confirm the existence of small patches of discrete aurora near crustal magnetic fields in Mars' southern hemisphere, as observed previously by SPICAM on Mars Express (Bertaux et al., Nature, 435, 790-794 (2005)). IUVS observed southern latitudes in July and August 2015, detecting discrete auroral emission in ~1% of suitable observations. Limb scans resolved both vertically and along-slit indicate this type of auroral emission was patchy on the scale of ~40 km, and located at higher altitudes ~140 km. The higher altitudes imply a lower energy of precipitating particles. The mix of spectral emissions also differed signficiantly from the diffuse aurora, indicating different excitation and quenching processes.We will discuss the observed properties of the aurora and associated charged particle precipitation, as well as the broader implications of this high

  17. Solar Polar Imager: Observing Coronal Transients from a New Perspective (Invited)

    NASA Astrophysics Data System (ADS)

    Liewer, P. C.

    2013-12-01

    The heliophysics community has long recognized the need for a mission to observe the Sun and corona from a polar perspective. One mission concept, the Solar Polar Imager (SPI), has been studied extensively (Liewer et al in NASA Space Science Vision Missions, 2008). In this concept, a solar sail is used to place a spacecraft in a circular 0.48-AU heliocentric orbit with an inclination of ~75 degrees. This orbit enables crucial observations not possible from lower latitude perspectives. Magnetograph and Doppler observations from a polar vantage point would revolutionize our understanding of the mechanism of solar activity cycles, polar magnetic field reversals, the internal structure and dynamics of the Sun and its atmosphere. The rapid 4-month polar orbit combined with both in situ and remote sensing instrumentation further enables unprecedented studies of the physical connection between the Sun, the solar wind, and solar energetic particles. From the polar perspective, white light imagers could be used to track CMEs and predict their arrival at Earth (as demonstrated by STEREO). SPI is also well suited to study the relative roles of CME-driven shock versus flare-associated processes in solar energetic particle acceleration. With the circular 0.48 AU orbit, solar energetic particles could be more easily traced to their sources and their variation with latitude can be studied at a constant radius. This talk will discuss the science objectives, instrumentation and mission design for the SPI mission.

  18. Cusp/cleft region as observed by the Viking UV imager

    SciTech Connect

    Garbe, G.P.; Murphree, J.S.; Cogger, L.L. ); Woch, J. )

    1993-04-01

    The authors report data taken by the Viking satellite at mid-altitudes (11,000-13,000 km) during northern hemispheric crossings of the cusp/cleft region. Particle signatures were used to divide the region into different categories. Data was looked at from the ultraviolet imager and particle diagnostics, when available. The authors discuss in detail two cases of crossing the cusp/cleft region, in order to look at the dynamics of a specific event, as opposed to other data analyses which have used large data sets to acquire good statistics, but which can thereby obscure dynamics of the actual events. Particle data were taken by the electron spectrometer ESP 1 and the ion spectrometer PISP 1/2. They looked at the spectral range 0.01 to 40 keV. The UV imager recorded 1 sec exposures of the auroral distribution once per minute. The data shows instantaneous observations of emissions, and does so for a narrow path swept by the satellite. Data indicate that the entire region is not a homogeneous region, but rather a very dynamic object. Conclusions include that the emissions observed are located at the footprint of the cleft region. The cusp region is located poleward of the region with continuous emission. The emission is observed to remain at a constant magnetic latitude during the period with IMF data, though B[sub z] swung 8nT during a 30 minute period.

  19. Obtaining coincident image observations for Mission to Planet Earth science data return

    NASA Technical Reports Server (NTRS)

    Newman, Lauri Kraft; Folta, David C.; Farrell, James P.

    1994-01-01

    One objective of the Mission to Planet Earth (MTPE) program involves comparing data from various instruments on multiple spacecraft to obtain a total picture of the Earth's systems. To correlate image data from instruments on different spacecraft, these spacecraft must be able to image the same location on the Earth at approximately the same time. Depending on the orbits of the spacecraft involved, complicated operational details must be considered to obtain such observations. If the spacecraft are in similar orbits, close formation flying or synchronization techniques may be used to assure coincident observations. If the orbits are dissimilar, the launch time of the second satellite may need to be restricted in order to align its orbit with that of the first satellite launched. This paper examines strategies for obtaining coincident observations for spacecraft in both similar and dissimilar orbits. Although these calculations may be performed easily for coplanar spacecraft, the non-coplanar case involves additional considerations which are incorporated into the algorithms presented herein.

  20. Collaborative real-time motion video analysis by human observer and image exploitation algorithms

    NASA Astrophysics Data System (ADS)

    Hild, Jutta; Krüger, Wolfgang; Brüstle, Stefan; Trantelle, Patrick; Unmüßig, Gabriel; Heinze, Norbert; Peinsipp-Byma, Elisabeth; Beyerer, Jürgen

    2015-05-01

    Motion video analysis is a challenging task, especially in real-time applications. In most safety and security critical applications, a human observer is an obligatory part of the overall analysis system. Over the last years, substantial progress has been made in the development of automated image exploitation algorithms. Hence, we investigate how the benefits of automated video analysis can be integrated suitably into the current video exploitation systems. In this paper, a system design is introduced which strives to combine both the qualities of the human observer's perception and the automated algorithms, thus aiming to improve the overall performance of a real-time video analysis system. The system design builds on prior work where we showed the benefits for the human observer by means of a user interface which utilizes the human visual focus of attention revealed by the eye gaze direction for interaction with the image exploitation system; eye tracker-based interaction allows much faster, more convenient, and equally precise moving target acquisition in video images than traditional computer mouse selection. The system design also builds on prior work we did on automated target detection, segmentation, and tracking algorithms. Beside the system design, a first pilot study is presented, where we investigated how the participants (all non-experts in video analysis) performed in initializing an object tracking subsystem by selecting a target for tracking. Preliminary results show that the gaze + key press technique is an effective, efficient, and easy to use interaction technique when performing selection operations on moving targets in videos in order to initialize an object tracking function.

  1. Ultraviolet imaging telescope and optical emission-line observations of H II regions in M81

    NASA Technical Reports Server (NTRS)

    Hill, Jesse K.; Cheng, K.-P.; Bohlin, Ralph C.; Cornett, Robert H.; Hintzen, P. M. N.; O'Connell, Robert W.; Roberts, Morton S.; Smith, Andrew M.; Smith, Eric P.; Stecher, Theodore P.

    1995-01-01

    Images of the type Sab spiral galaxy M81 were obtained in far-UV and near-UV bands by the Ultraviolet Imaging Telescope (UIT) during the Astro-1 Spacelab mission of 1990 December. Magnitudes in the two UV bands are determined for 52 H II regions from the catalog of Petit, Sivan, & Karachentsev (1988). Fluxes of the H-alpha and H-beta emission lines are determined from CCD images. Extinctions for the brightest H II regions are determined from observed Balmer decrements. Fainter H II regions are assigned the average of published radio-H-alpha extinctions for several bright H II regions. The radiative transfer models of Witt, Thronson, & Capuano (1992) are shown to predict a relationship between Balmer Decrement and H-alpha extinction consistent with observed line and radio fluxes for the brightest 7 H II regions and are used to estimate the UV extinction. Ratios of Lyman continuum with ratios predicted by model spectra computed for initial mass function (IMF) slope equal to -1.0 and stellar masses ranging from 5 to 120 solar mass. Ages and masses are estimated by comparing the H-alpha and far-UV fluxes and their ratio with the models. The total of the estimated stellar masses for the 52 H II regions is 1.4 x 10(exp 5) solar mass. The star-formation rate inferred for M81 from the observed UV and H-alpha fluxes is low for a spiral galaxy at approximately 0.13 solar mass/yr, but consistent with the low star-formation rates obtained by Kennicutt (1983) and Caldwell et al. (1991) for early-type spirals.

  2. Atomic oxygen on the Venus nightside: Global distribution deduced from airglow mapping

    NASA Astrophysics Data System (ADS)

    Soret, L.; Gérard, J.-C.; Montmessin, F.; Piccioni, G.; Drossart, P.; Bertaux, J.-L.

    2012-02-01

    The Visible and Infra-Red Thermal Imaging Spectrometer (VIRTIS) instrument on board the Venus Express spacecraft has measured the O 2(a 1Δ) nightglow distribution at 1.27 μm in the Venus mesosphere for more than two years. Nadir observations have been used to create a statistical map of the emission on Venus nightside. It appears that the statistical 1.6 MR maximum of the emission is located around the antisolar point. Limb observations provide information on the altitude and on the shape of the emission layer. We combine nadir observations essentially covering the southern hemisphere, corrected for the thermal emission of the lower atmosphere, with limb profiles of the northern hemisphere to generate a global map of the Venus nightside emission at 1.27 μm. Given all the O 2(a 1Δ) intensity profiles, O 2(a 1Δ) and O density profiles have been calculated and three-dimensional maps of metastable molecular and atomic oxygen densities have been generated. This global O density nightside distribution improves that available from the VTS3 model, which was based on measurements made above 145 km. The O 2(a 1Δ) hemispheric average density is 2.1 × 10 9 cm -3, with a maximum value of 6.5 × 10 9 cm -3 at 99.2 km. The O density profiles have been derived from the nightglow data using CO 2 profiles from the empirical VTS3 model or from SPICAV stellar occultations. The O hemispheric average density is 1.9 × 10 11 cm -3 in both cases, with a mean altitude of the peak located at 106.1 km and 103.4 km, respectively. These results tend to confirm the modeled values of 2.8 × 10 11 cm -3 at 104 km and 2.0 × 10 11 cm -3 at 110 km obtained by Brecht et al. [Brecht, A., Bougher, S.W., Gérard, J.-C., Parkinson, C.D., Rafkin, S., Foster, B., 2011a. J. Geophys. Res., in press] and Krasnopolsky [Krasnopolsky, V.A., 2010. Icarus 207, 17-27], respectively. Comparing the oxygen density map derived from the O 2(a 1Δ) nightglow observations, it appears that the morphology is very

  3. Science objectives and observing strategy for the OMEGA imaging spectrometer on Mars-Express

    NASA Astrophysics Data System (ADS)

    Erard, S.; Bibring, J.-P.; Drossart, P.; Forget, F.; Schmitt, B.; OMEGA Team

    2003-04-01

    The science objectives of OMEGA, which were first defined at the time of instruments selection for Mars-Express, were recently updated to integrate new results from MGS and Odyssey concerning three main fields: Martian surface and atmosphere, and polar processes. Thematic categories of observations are derived from the scientific objectives whenever spectral observations from OMEGA are expected to provide insights to Mars present situation and evolution. Targets within these categories are selected on the basis of their expected usefulness, which is related to their intrinsic properties and to the instrument capabilities. The whole surface will be mapped at low resolution (~5 km/pixel) in the course of the nominal mission, and possibly routinely at very coarse resolution to monitor time-varying processes from apocenter. However, only 5% of the surface can be observed at high resolution (up to 350 m/pixel) owing to constraints on telemetry rate. HR targets are therefore selected on the basis of telemetry constraints, orbital parameters, observing opportunities (visibility under given conditions), and spacecraft functionalities (e.g., depointing capacity), then prioritized within each category according to the probability to perform significant observations with OMEGA (in many situations, according to the estimated dust coverage). Target selection is performed interactively between OMEGA co-Is, in close contact with teams from other MEx experiments (mostly HRSC, PFS and Spicam) and other missions (e.g., MER and MRO). Most HR surface targets are selected on the basis of deep examination of Viking, THEMIS, and MOC HR images. Other surface targets include areas presenting unusual spectral properties in previous observations, or suspected to exhibit signatures of hydrothermal activity. Proposed landing sites and suggested source areas for the SNC meteorites are also included. Atmospheric/polar objectives more often translate as particular observing modes, sometimes at HR

  4. Observations of the quasi 2-day wave from the High Resolution Doppler Imager on UARS

    NASA Technical Reports Server (NTRS)

    Wu, D. L.; Hays, P. B.; Skinner, W. R.; Marshall, A. R.; Burrage, M. D.; Lieberman, R. S.; Ortland, D. A.

    1993-01-01

    A strong westward traveling oscillation, with a period of 2 days and zonal wave number 3, is observed in the mesospheric and lower thermospheric winds from the High Resolution Doppler Imager (HRDI) on the Upper Atmosphere Research Satellite (UARS). The important events happen in January, July, and September/October, of which the occurrence in January is the strongest with an amplitude over 60 m/s. Detailed analyses for the periods of January 1992 and January 1993 reveal a cause-and-effect relationship in the wave developing process at 95 km. The global structures of the wave amplitude and phase are also presented.

  5. Use of digital images to observe forest phenology and drought stress

    NASA Astrophysics Data System (ADS)

    Ahrends, H. E.; Etzold, S.; Eugster, W.; Buchmann, N.; Jeanneret, F.; Wanner, H.

    2009-04-01

    Phenological data that complement research studies of climate impacts on ecosystems need to be estimated with both temporal and spatial accuracy. Forest phenology can be monitored by satellite, but the realism of remote sensing products such as the NDVI (Normalized Difference Vegetation Index) still heavily depends on ground based validation data. Ground based data is often observer-biased and the number of observations strongly varies in time and space. Recent studies have demonstrated the successful application of digital camera images for spring phenological monitoring in ecosystem studies. Objective of the present study therefore was to test the application of digital images from standard RGB-cameras for regional monitoring and modelling the seasonality of forest physiology and for detecting species-specific reactions on environmental impacts such as drought. A digital camera was mounted on the uppermost platform of a fluxtower at the CarboEurope site Lägeren (northern Switzerland). Daily images of the mixed forest from four years were used to derive the timing of greenup, leaf maturity, senescence and dormancy of two different tree species (beech and ash) between 2005 and 2008. Based on the image color values a vegetation index was computed. Time series of the vegetation index were jointly analyzed with standard meteorological data and eddy covariance measurements of ecosystem carbon dioxide and water vapour exchange. Generally the observation of phenologial phases was successful but complex for the end of the vegetation period, e.g. due to early leaf coloring caused by summer heat, and a less pronounced starting date of leaf senescence compared with spring greenup. Spring CO2 flux characteristics could be explained by leaf emergence dates of dominant tree species. A drought period in 2006 influenced index values for beech but not for the highly drought-tolerant ash trees. Phenological data showed significant correlation with carbon dioxide exchange

  6. Earth Observing-1 Advanced Land Imager: Dark Current and Noise Characterization and Anomalous Detectors

    NASA Technical Reports Server (NTRS)

    Mendenhall, J. A.

    2001-01-01

    The dark current and noise characteristics of the Earth Observing-1 Advanced Land Imager measured during ground calibration at MIT Lincoln Laboratory are presented. Data were collected for the nominal focal plane operating temperature of 220 K as well as supplemental operating temperatures (215 and 225 K). Dark current baseline values are provided, and noise characterization includes the evaluation of white, coherent, low frequency, and high frequency components. Finally, anomalous detectors, characterized by unusual dark current, noise, gain, or cross-talk properties are investigated.

  7. Use of the Hotelling observer to optimize image reconstruction in digital breast tomosynthesis.

    PubMed

    Sánchez, Adrian A; Sidky, Emil Y; Pan, Xiaochuan

    2016-01-01

    We propose an implementation of the Hotelling observer that can be applied to the optimization of linear image reconstruction algorithms in digital breast tomosynthesis. The method is based on considering information within a specific region of interest, and it is applied to the optimization of algorithms for detectability of microcalcifications. Several linear algorithms are considered: simple back-projection, filtered back-projection, back-projection filtration, and [Formula: see text]-tomography. The optimized algorithms are then evaluated through the reconstruction of phantom data. The method appears robust across algorithms and parameters and leads to the generation of algorithm implementations which subjectively appear optimized for the task of interest. PMID:26702408

  8. Visual adaptation: softcopy image contribution to the observer's field of view

    NASA Astrophysics Data System (ADS)

    Toomey, R. J.; Curran, K.; D'Helft, C.; Joyce, M. B.; Stowe, J.; Ryan, J. T.; McEntee, M. F.; Manning, D. J.; Brennan, P. C.

    2008-03-01

    Purpose Detection of low-contrast details is highly dependent on the adaptation state of the eye. It is important therefore that the average luminance of the observer's field of view (FOV) matches those of softcopy radiological images. This study establishes the percentage of FOV filled by workstations at various viewing distances. Methods Five observers stood at viewing distances of 20, 30 and 50cm from a homogenous white surface and were instructed to continuously focus on a fixed object at a height appropriate level. A dark indicator was held at this object and then moved steadily until the observer could no longer perceive it in his/her peripheral vision. This was performed at 0°, 90°, 180° and 270° clockwise from the median sagittal plane. Distances were recorded, radii calculated and observer and mean FOV areas established. These values were then compared with areas of typical high and low specification workstations. Results Individual and mean FOVs were 7660, 15463 and 30075cm2 at viewing distances of 20, 30 and 50cm respectively. High and low specification monitors with respective areas of 1576.25 and 921.25cm2 contributed between 5 to 21% and 3 to 12% respectively to the total FOV depending on observer distance. Limited inter-observer variances were noted. Conclusions Radiology workstations typically comprise between only 3 and 21% of the observer's FOV. This demonstrates the importance of measuring ambient light levels and surface reflection coefficients in order to maximise adaptation and observer's perception of low contrast detail and minimise eye strain.

  9. Spectral and Imaging Observations of a White-light Solar Flare in the Mid-infrared

    NASA Astrophysics Data System (ADS)

    Penn, Matt; Krucker, Säm; Hudson, Hugh; Jhabvala, Murzy; Jennings, Don; Lunsford, Allen; Kaufmann, Pierre

    2016-03-01

    We report high-resolution observations at mid-infrared wavelengths of a minor solar flare, SOL2014-09-24T17:50 (C7.0), using Quantum Well Infrared Photodetector cameras at an auxiliary of the McMath-Pierce telescope. The flare emissions, the first simultaneous observations in two mid-infrared bands at 5.2 and 8.2 μ {{m}} with white-light and hard X-ray coverage, revealed impulsive time variability with increases on timescales of ˜4 s followed by exponential decay at ˜10 s in two bright regions separated by about 13\\prime\\prime . The brightest source is compact, unresolved spatially at the diffraction limit (1\\_\\_AMP\\_\\_farcs;72 at 5.2 μ {{m}}). We identify the IR sources as flare ribbons also seen in white-light emission at 6173 Å observed by SDO/HMI, with twin hard X-ray sources observed by Reuven Ramaty High Energy Solar Spectroscopic Imager, and with EUV sources (e.g., 94 Å) observed by SDO/AIA. The two infrared points have nearly the same flux density (fν, W m-2 Hz) and extrapolate to a level of about an order of magnitude below that observed in the visible band by HMI, but with a flux of more than two orders of magnitude above the free-free continuum from the hot (˜15 MK) coronal flare loop observed in the X-ray range. The observations suggest that the IR emission is optically thin; this constraint and others suggest major contributions from a density less than about 4× {10}13 cm-3. We tentatively interpret this emission mechanism as predominantly free-free emission in a highly ionized but cool and rather dense chromospheric region.

  10. All Sky Imager Network for Science and Education

    NASA Astrophysics Data System (ADS)

    Bhatt, A.; Kendall, E. A.; Zalles, D. R.; Baumgardner, J. L.; Marshall, R. A.; Kaltenbacher, E.

    2012-12-01

    A new all sky imager network for space weather monitoring and education outreach has been developed by SRI International. The goal of this program is to install sensitive, low-light all-sky imagers across the continental United States to observe upper atmospheric airglow and aurora in near real time. While aurora borealis is often associated with the high latitudes, during intense geomagnetic storms it can extend well into the continental United States latitudes. Observing auroral processes is instrumental in understanding the space weather, especially in the times of increasing societal dependence on space-based technologies. Under the THEMIS satellite program, Canada has installed a network of all-sky imagers across their country to monitor aurora in real-time. However, no comparable effort exists in the United States. Knowledge of the aurora and airglow across the entire United States in near real time would allow scientists to quickly assess the impact of a geomagnetic storm in concert with data from GPS networks, ionosondes, radars, and magnetometers. What makes this effort unique is that we intend to deploy these imagers at high schools across the country. Selected high-schools will necessarily be in rural areas as the instrument requires dark night skies. At the commencement of the school year, we plan to give an introductory seminar on space weather at each of these schools. Science nuggets developed by SRI International in collaboration with the Center for GeoSpace Studies and the Center for Technology in Learning will be available for high school teachers to use during their science classes. Teachers can use these nuggets as desired within their own curricula. We intend to develop a comprehensive web-based interface that will be available for students and scientific community alike to observe data across the network in near real time and also to guide students towards complementary space weather data sets. This interface will show the real time extent of

  11. Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) observations during several 2013 NASA field campaigns

    NASA Astrophysics Data System (ADS)

    Diner, D. J.; Garay, M. J.; Xu, F.; Kalashnikova, O.; Rheingans, B.; Geier, S.; Val, S.; Bull, M.; Jovanovic, V.; Bruegge, C.; Seidel, F. C.; Daugherty, B.; Chipman, R.; Davis, A.

    2013-12-01

    The Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) is an ultraviolet/visible/near-infrared pushbroom camera mounted on a single-axis gimbal to acquire multiangle imagery over a ×67° along-track range. The instrument flies aboard NASA's high-altitude ER-2 aircraft, and acquires Earth imagery with ~10 m spatial resolution across an 11-km wide swath. Intensity (I) images are obtained in eight spectral bands (355, 380, 445, 470, 555, 660, 865, and 935 nm). Dual photoelastic modulators (PEMs), achromatic quarter-wave plates, and wire-grid polarizers enable imagery of the linear polarization Stokes components Q and U at 470, 660, and 865 nm. The data are used to derive degree of linear polarization (DOLP) and angle of linear polarization (AOLP). Example flight data acquired during various NASA field campaigns in 2013, including the Aerosol-Cloud-Ecosystem (ACE) Polarimeter Definition Experiment (PODEX), Hyperspectral Infrared Imager (HyspIRI), and Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) are presented. Observations of aerosols, low- and mid-level cloud fields, cirrus, and different types of surfaces under clear skies were obtained for a variety of land and ocean targets. Radiance and polarization imagery for several scenes, along with modeling of aerosol, cloud, and surface scattering, are presented to illustrate quantitatively some of the instrument's capabilities. Laboratory and vicarious calibration results are also discussed.

  12. Imaging observations of Jupiter's sodium magneto-nebula during the Ulysses encounter

    NASA Technical Reports Server (NTRS)

    Mendillo, Michael; Flynn, Brian; Baumgardner, Jeffrey

    1992-01-01

    Jupiter's great sodium nebula represents the largest visible structure traversed by the Ulysses spacecraft during its encounter with the planet in February 1992. Ground-based imaging conducted on Mount Haleakala, Hawaii, revealed a nebula that extended to at least +/- 300 Jovian radii; it was somewhat smaller in scale and less bright than previously observed. Analysis of observations and results of modeling studies suggest reduced volcanic activity on the moon Io, higher ion temperatures in the plasma torus, lower total plasma content in the torus, and fast neutral atomic clouds along the Ulysses inbound trajectory through the magnetosphere. Far fewer neutrals were encountered by the spacecraft along its postencounter, out-of-ecliptic trajectory.

  13. Observation of Snow Cover Variations at Mt. Kilimanjaro Using Landsat TM and ETM+ Images

    NASA Astrophysics Data System (ADS)

    Park, S.; Jung, H.; Lee, M.; Jung, H.

    2012-12-01

    Since the industrial revolution began, CO2 levels have been increasing with climate change. The objectives of this study are to quantitatively analyze snow cover area and distribution according to height changes with respect to time and to statistically predict the date of snow cover disappearance using remote sensing data over Mt. Kilimanjaro, Tanzania. Total numbers of 23 Landsat-5 TM and Landsat-7 ETM+ images are used for observing the snow cover variation, spanning the 27 years from June 1984 to July 2011. For this observation of snow cover variations, the following steps are applied: 1) atmospheric correction is performed on each image using the cosine approximation (COST) atmospheric correction algorithm, 2) the snow cover area is extracted from the normalized difference snow index (NDSI) algorithm, 3) the minimum height is determined using SRTM DEM and extracted snow cover area, and 4) the date of snow cover disappearance is predicted using a linear regression model. Among 23 images, seventeen images of the dry season are used for analyzing snow cover changes. Results show that snow cover area for about 30 years are largely changed from 9.01 km2 to 2.54 km2, equivalent to a 73% reduction. The minimum height of snow cover increased by approximately 290 m, from 4,603 m to 4,893 m. Linear regression model result shows that the snow cover area decreased by about 0.34 km2/yr and the minimum height of snow cover increased by about 9.85 m/yr. Moreover, L-band synthetic aperture radar (SAR) images are used to analyze seasonal variation of snow cover from 2006 to 2011. The results indicate that snow cover area of Mt. Kilimanjaro has fast decreased according to global warming. *This work was researched by the supporting project to educate GIS experts; Distribution of elevations for snow-covered area: (a) 24 Jun. 1984 and (b) 21 Jul. 2011 ; Changes of snow-covered area with respect to surface elevation: (a) 24 Jun. 1984 and (b) 21 Jul. 2011

  14. Conjugate Observations of Optical Aurora with POLAR Satellite and Ground Based Imagers in Antarctica

    NASA Technical Reports Server (NTRS)

    Mende, S. H.; Frey, H.; Vo, H.; Geller, S. P.; Doolittle, J. H.; Spann, J. F., Jr.

    1998-01-01

    Operation of the ultraviolet imager on the POLAR satellite permits the observation of Aurora Borealis in daylight during northern summer. With optical imagers in the Automatic Geophysical Observatories (AGO-s) large regions of the oval of Aurora Australis can be observed simultaneously during the southern winter polar night. This opportunity permits conducting a systematic study of the properties of auroras on opposite ends of the same field line. It is expected that simultaneously observed conjugate auroras occurring on closed field lines should be similar to each other in appearance because of the close connection between the two hemispheres through particle scattering and mirroring processes. On open or greatly distorted field lines there is no a priori expectation of similarity between conjugate auroras. To investigate the influence of different IMF conditions on auroral behavior we have examined conjugate data for periods of southward IMF. Sudden brightening and subsequent poleward expansions are observed to occur simultaneously in both hemispheres. The POLAR data show that sudden brightening are initiated at various local time regions. When the local time of this region is in the field of view of the AGO station network then corresponding brightening is also found to occur in the southern hemisphere. Large features such as substorm induced westward propagation and resulting auroral brightening seem to occur simultaneously on conjugate hemispheres. The widely different view scales make it difficult to make unique identification of individual auroral forms in the POLAR and in the ground based data but in a general sense the data is consistent with conjugate behavior.

  15. Surface Wind Vector and Rain Rate Observation Capability of Future Hurricane Imaging Radiometer (HIRAD)

    NASA Technical Reports Server (NTRS)

    Miller, Timothy; Atlas, Robert; Bailey, M. C.; Black, Peter; El-Nimri, Salem; Hood, Robbie; James, Mark; Johnson, James; Jones, Linwood; Ruf, Christopher; Uhlhorn, Eric

    2009-01-01

    The Hurricane Imaging Radiometer (HIRAD) is the next-generation Stepped Frequency Microwave Radiometer (SFMR), and it will offer the capability of simultaneous wide-swath observations of both extreme ocean surface wind vector and strong precipitation from either aircraft (including UAS) or satellite platforms. HIRAD will be a compact, lightweight, low-power instrument with no moving parts that will produce valid wind observations under hurricane conditions when existing microwave sensors (radiometers or scatterometers) are hindered by precipitation. The SFMR i s a proven aircraft remote sensing system for simultaneously observing extreme ocean surface wind speeds and rain rates, including those of major hurricane intensity. The proposed HIRAD instrument advances beyond the current nadir viewing SFMR to an equivalent wide-swath SFMR imager using passive microwave synthetic thinned aperture radiometer technology. The first version of the instrument will be a single polarization system for wind speed and rain rate, with a dual-polarization system to follow for wind vector capability. This sensor will operate over 4-7 GHz (C-band frequencies) where the required tropical cyclone remote sensing physics has been validated by both SFMR and WindSat radiometers. HIRAD incorporates a unique, technologically advanced array antenna and several other technologies successfully demonstrated by NASA s Instrument Incubator Program. A brassboard (laboratory) version of the instrument has been completed and successfully tested in a test chamber. Development of the aircraft instrument is underway, with flight testing planned for the fall of 2009. Preliminary Observing System Simulation Experiments (OSSEs) show that HIRAD will have a significant positive impact on surface wind analyses as either a new aircraft or satellite sensor. New off-nadir data collected in 2008 by SFMR that affirms the ability of this measurement technique to obtain wind speed data at non-zero incidence angle will

  16. Mars' Active Surface: Observing Changes with Orthorectified HiRISE Images

    NASA Astrophysics Data System (ADS)

    Mattson, S.; McEwen, A. S.; Ojha, L.; Bridges, N. T.; Kirk, R. L.; Howington-Kraus, E.; Mogk, N.

    2012-12-01

    Active processes on Mars have been observed and documented with high resolution images from orbit. The HiRISE camera, operating on MRO since 2006, acquires images of the surface of Mars at up to 25 cm pixel scale, and has stereo capability. The use of HiRISE stereo images to produce digital terrain models (DTMs) allows for orthorectification of the stereo pair and other images targeted over the same area. HiRISE DTMs typically have 1 or 2 m horizontal resolution with vertical precision on the order of 10's of cm. DTM production with HiRISE requires that the source stereo pair has similar lighting and minimal surface differences. However, there is no similar requirement for orthorectifying other images taken of the same area. Changes on the surface can then be measured accurately in the orthoimages as topographic distortions have been minimized. Time sequences of surface changes can be constructed from a series of orthoimages, providing essential data for understanding their rate and magnitude. Some of the current areas of study using HiRISE DTMs and orthoimages include recurring slope lineae (RSL) (McEwen et al., Science 333, 740, 2011), dune and ripple migration (Bridges et al., Nature 485, 339, 2012), seasonal frost changes, and gully activity. In some cases, DTMs from before and after significant surface movement can be compared to measure volumetric changes. The demand for HiRISE DTMs and orthoimages has led to advances in techniques for their production and analysis. Improved image processing and terrain editing tools result in better DTMs and orthoimages, as well as minimize the time required to produce them. We present here ongoing work to refine these techniques and develop new methods for generating orthoimage sequences, including orthorectification of the HiRISE 3-band color strip. Results are illustrated using series of orthoimages over dunes, RSL sites and other areas of Martian surface activity. HiRISE DTMs and orthoimages are released to the Planetary

  17. VLBA observations of a rare multiple quasar imaging event caused by refraction in the interstellar medium

    NASA Astrophysics Data System (ADS)

    Pushkarev, A. B.; Kovalev, Y. Y.; Lister, M. L.; Hovatta, T.; Savolainen, T.; Aller, M. F.; Aller, H. D.; Ros, E.; Zensus, J. A.; Richards, J. L.; Max-Moerbeck, W.; Readhead, A. C. S.

    2013-07-01

    Aims: We have investigated highly atypical morphological parsec-scale changes in the flat spectrum extragalactic radio source 2023+335 which are coincident with an extreme scattering event (ESE) seen at radio wavelengths during the first half of 2009. Methods: We used (i) 15.4 GHz Very Long Baseline Array (VLBA) observations of the quasar 2023+335 obtained at 14 epochs between July 2008 and Nov. 2012 as part of the Monitoring Of Jets in Active galactic nuclei with VLBA Experiments (MOJAVE) program; (ii) earlier archival VLBA observations of the source performed at 1.4, 2, 8, 15, 22, and 86 GHz to analyze the properties of the proposed turbulent screen toward 2023 + 335; and (iii) data sets from the Owens Valley Radio Observatory (OVRO) and University of Michigan Radio Astronomy Observatory (UMRAO) single-dish monitoring programs performed at 15 and 14.5 GHz, respectively, to study integrated flux density changes. Results: We report on the first detection of the theoretically-predicted rare phenomenon of multiple parsec-scale imaging of an active galactic nucleus induced by refractive effects due to localized foreground electron density enhancements, e.g., in an AU-scale plasma lens(es) in the ionized component of the Galactic interstellar medium. We detected multiple imaging in the low galactic latitude (b = -2.°4) quasar 2023+335 from the 15.4 GHz MOJAVE observations when the source was undergoing an ESE. While the parsec-scale jet of the source normally extends along PA ~ -20°, in the 28 May 2009 and 23 July 2009 images a highly significant multi-component pattern of secondary images is stretched out nearly along the constant galactic latitude line with a local PA ≈ 40°, indicating that the direction of relative motion of the plasma lens is close to orbital. Weaker but still detectable imaging patterns at similar position angles are sporadically manifest at several other epochs. Modeling the ESE that occurred in early 2009 and lasted ~0.14 yr, we determined

  18. The deep structure of the Western Pyrenees: constraints from tomographic imaging, field and marine geological observations

    NASA Astrophysics Data System (ADS)

    Tugend, Julie; Manatschal, Gianreto; Chevrot, Sébastien; Mohn, Geoffroy

    2015-04-01

    Knowledge of magma-poor rifted margin architecture has significantly evolved over the past decades. Refraction seismic data combined with drill-hole observations unravelled the velocity structure and lithological assemblages of the most distal part of continental rifted margins. Present-day models of continental rifted margins include the occurrence of hyperextended domains consisting in extremely thinned continental crust and/or exhumed subcontinental mantle as described at many rifted margins. Studies in mountain belts revealed that remnants of hyperextended domains could also be identified in internal parts of collisional orogens. Integrating recent developments in the understanding of rifted margins in the study of mountain building processes, in particular the importance of the reactivation of inherited rift structures is therefore essential and may result in alternative interpretations of the lithospheric scale structure of collisional orogens. In this contribution, we focus on the western part of the Pyrenean orogen that resulted from the inversion of a complex Late Jurassic to Mid Cretaceous rift system. The transition from preserved oceanic and rift domains to the west (in the offshore Bay of Biscay) to their complete inversion in the east provides simultaneous access to seismically imaged and exposed parts of a hyperextended rift system. Based on a multi-scale dataset that combines sub-surface data (field and drill-hole observations) with tomographic imaging (PYROPE experiment) and integrating new concepts derived from the study of present-day rifted margins, we investigate the lithospheric-scale architecture of the Western Pyrenees. Our results suggest that the imaged north-dipping crustal root may correspond to the former exhumed mantle and hyperthinned domains that have been subducted/underthrust at the onset of convergence. This interpretation contrasts with the classical assumption that the crustal root is made of lower crustal rocks. This

  19. Anisotropic superconductivity observed by magneto-optical imaging: A case study of yttrium barium copper oxide

    NASA Astrophysics Data System (ADS)

    Wang, Chong

    This work studies direct Magneto-Optical Imaging (MOI) as a means to directly observe anisotropic superconductivity using (110)-oriented YBa 2Cu3O7-delta (YBCO) thin film. The MOI technique can translate magnetic field distribution directly into an optical image. It has been used to study supercurrent distribution in a superconducting thin film. A fast Fourier transform method was developed to convert the MO image into maps of current density distribution independent of the underlying models that are used to extract the critical current densities. By using this method, the inhomogeneous critical current distribution can be deduced, and current stream maps can be constructed. High quality single phase YBCO (110) thin films were fabricated by magnetron sputtering. Characterizations by X-ray diffraction, Rutherford backscattering and channeling, a scanning electron microscope, an atomic force microscope, and electric transport measurement indicates that the (110) films are single-phased, strain-free, highly oxygenated, and have a relatively smooth surface compared to the c-axis oriented counterpart prepared by the same technique. Direct imaging of the anisotropic magnetic field distribution at the surface of YBCO (110) thin film has been realized, where the unique stripe-like pattern is interpreted as based on the anisotropic critical current density model developed in this work. Geometric effects on anisotropic critical current flow have been examined. The characteristic behaviors of parabola-shaped discontinuity-lines (d-line) in an anisotropic thin film sample are discussed. Calculations of the critical currents at step-edged defects on anisotropic thin-films strip were conducted. The magnetic field pattern derived from the calculation is in good agreement with the stripe pattern of the experiment. Such step-edges are representative of physical imperfections that dictate the presence or absence of the stripe pattern in an anisotropic superconductor.

  20. Statistical correlation of low-altitude ENA emissions with geomagnetic activity from IMAGE/MENA observations

    NASA Astrophysics Data System (ADS)

    Mackler, D. A.; Jahn, J.-M.; Perez, J. D.; Pollock, C. J.; Valek, P. W.

    2016-03-01

    Plasma sheet particles transported Earthward during times of active magnetospheric convection can interact with exospheric/thermospheric neutrals through charge exchange. The resulting Energetic Neutral Atoms (ENAs) are free to leave the influence of the magnetosphere and can be remotely detected. ENAs associated with low-altitude (300-800 km) ion precipitation in the high-latitude atmosphere/ionosphere are termed low-altitude emissions (LAEs). Remotely observed LAEs are highly nonisotropic in velocity space such that the pitch angle distribution at the time of charge exchange is near 90°. The Geomagnetic Emission Cone of LAEs can be mapped spatially, showing where proton energy is deposited during times of varying geomagnetic activity. In this study we present a statistical look at the correlation between LAE flux (intensity and location) and geomagnetic activity. The LAE data are from the MENA imager on the IMAGE satellite over the declining phase of solar cycle 23 (2000-2005). The SYM-H, AE, and Kp indices are used to describe geomagnetic activity. The goal of the study is to evaluate properties of LAEs in ENA images and determine if those images can be used to infer properties of ion precipitation. Results indicate a general positive correlation to LAE flux for all three indices, with the SYM-H showing the greatest sensitivity. The magnetic local time distribution of LAEs is centered about midnight and spreads with increasing activity. The invariant latitude for all indices has a slightly negative correlation. The combined results indicate LAE behavior similar to that of ion precipitation.

  1. Application of a multiscale maximum entropy image restoration algorithm to HXMT observations

    NASA Astrophysics Data System (ADS)

    Guan, Ju; Song, Li-Ming; Huo, Zhuo-Xi

    2016-08-01

    This paper introduces a multiscale maximum entropy (MSME) algorithm for image restoration of the Hard X-ray Modulation Telescope (HXMT), which is a collimated scan X-ray satellite mainly devoted to a sensitive all-sky survey and pointed observations in the 1–250 keV range. The novelty of the MSME method is to use wavelet decomposition and multiresolution support to control noise amplification at different scales. Our work is focused on the application and modification of this method to restore diffuse sources detected by HXMT scanning observations. An improved method, the ensemble multiscale maximum entropy (EMSME) algorithm, is proposed to alleviate the problem of mode mixing exiting in MSME. Simulations have been performed on the detection of the diffuse source Cen A by HXMT in all-sky survey mode. The results show that the MSME method is adapted to the deconvolution task of HXMT for diffuse source detection and the improved method could suppress noise and improve the correlation and signal-to-noise ratio, thus proving itself a better algorithm for image restoration. Through one all-sky survey, HXMT could reach a capacity of detecting a diffuse source with maximum differential flux of 0.5 mCrab. Supported by Strategic Priority Research Program on Space Science, Chinese Academy of Sciences (XDA04010300) and National Natural Science Foundation of China (11403014)

  2. Observation of Dipole-Bound State and High-Resolution Photoelectron Imaging of Cold Acetate Anions

    NASA Astrophysics Data System (ADS)

    Zhu, Guo-Zhu; Huang, Dao-Ling; Wang, Lai-Sheng

    2015-06-01

    We report the observation of a dipole-bound state and a high-resolution photoelectron imaging study of cryogenically cooled acetate anions (CH3COO-). Both high-resolution non-resonant and resonant photoelectron spectra via the dipole-bound state of CH3COO- are obtained. The binding energy of the dipole-bound state relative to the detachment threshold is determined to be 53 ±{8} wn. The electron affinity of the CH_3COObullet neutral radical is measured accurately as 26 236 ±{8} wn (3.2528 ±{ 0.0010} eV) using high-resolution photoelectron imaging. This accurate electron affinity is validated by observation of autodetachment from two vibrational levels of the dipole-bound state of CH3COO-. Excitation spectra to the dipole-bound states yield rotational profiles, allowing the rotational temperature of the trapped CH3COO- anions to be evaluated 1. [1] D. L. Huang, G. Z. Zhu and L. S. Wang, J. Chem. Phys., 2015, 142, 091103

  3. ATMOSPHERIC IMAGING ASSEMBLY OBSERVATIONS OF CORONAL LOOPS: CROSS-FIELD TEMPERATURE DISTRIBUTIONS

    SciTech Connect

    Schmelz, J. T.; Jenkins, B. S.; Pathak, S.

    2013-06-10

    We construct revised response functions for the Atmospheric Imaging Assembly (AIA) using the new atomic data, ionization equilibria, and coronal abundances available in CHIANTI 7.1. We then use these response functions in multithermal analysis of coronal loops, which allows us to determine a specific cross-field temperature distribution without ad hoc assumptions. Our method uses data from the six coronal filters and the Monte Carlo solutions available from our differential emission measure (DEM) analysis. The resulting temperature distributions are not consistent with isothermal plasma. Therefore, the observed loops cannot be modeled as single flux tubes and must be composed of a collection of magnetic strands. This result is now supported by observations from the High-resolution Coronal Imager, which show fine-scale braiding of coronal strands that are reconnecting and releasing energy. Multithermal analysis is one of the major scientific goals of AIA, and these results represent an important step toward the successful achievement of that goal. As AIA DEM analysis becomes more straightforward, the solar community will be able to take full advantage of the state-of-the-art spatial, temporal, and temperature resolution of the instrument.

  4. The High Energy X-ray Imager Technology (HEXITEC) for Solar Hard X-ray Observations

    NASA Astrophysics Data System (ADS)

    Christe, Steven; Shih, Albert Y.; Gaskin, Jessica; Wilson-Hodge, Colleen; Seller, Paul; Wilson, Matthew

    2015-04-01

    High angular resolution HXR optics require detectors with a large number of fine pixels in order to adequately sample the telescope point spread function (PSF) over the entire field of view. Excessively over-sampling the PSF will increase readout noise and require more processing with no appreciable increase in image quality. An appropriate level of over-sampling is to have 3 pixels within the HPD. For current high resolution X-ray mirrors, the HPD is about 25 arcsec. Over a 6-m focal length this converts to 750 µm, the optimum pixel size is around 250 µm. Annother requirement are that the detectors must also have high efficiency in the HXR region, good energy resolution, low background, low power requirements, and low sensitivity to radiation damage. For solar observations, the ability to handle high counting rates is also extremely desirable. The Rutherford Appleton Laboratory (RAL) in the UK has been developing the electronics for such a detector. Dubbed HEXITEC, for High Energy X-Ray Imaging Technology, this Application Specific Integrated Circuit (ASIC), can be bonded to 1- or 2- mm-thick Cadmium Telluride (CdTe) or Cadmium-Zinc-Telluride (CZT), to create a fine (250 µm pitch) HXR detector. The NASA Marshall Space Flight CenterMSFC and the Goddard Space Flight Center (GSFC) has been working with RAL over the past few years to develop these detectors to be used with HXR focusing telescopes. We present on recent results and capabilities as applied to solar observations.

  5. Observations of 6.7 GHz methanol masers with East-Asian VLBI Network. I. VLBI images of the first epoch of observations

    NASA Astrophysics Data System (ADS)

    Fujisawa, Kenta; Sugiyama, Koichiro; Motogi, Kazuhito; Hachisuka, Kazuya; Yonekura, Yoshinori; Sawada-Satoh, Satoko; Matsumoto, Naoko; Sorai, Kazuo; Momose, Munetake; Saito, Yu; Takaba, Hiroshi; Ogawa, Hideo; Kimura, Kimihiro; Niinuma, Kotaro; Hirano, Daiki; Omodaka, Toshihiro; Kobayashi, Hideyuki; Kawaguchi, Noriyuki; Shibata, Katsunori M.; Honma, Mareki; Hirota, Tomoya; Murata, Yasuhiro; Doi, Akihiro; Mochizuki, Nanako; Shen, Zhiqiang; Chen, Xi; Xia, Bo; Li, Bin; Kim, Kee-Tae

    2014-04-01

    Very-long-baseline interferometry (VLBI) monitoring of the 6.7 GHz methanol maser allows us to measure the internal proper motion of maser spots and therefore study the gas motion around high-mass young stellar objects. To this end, we have begun monitoring observations with the East-Asian VLBI Network. In this paper we present the results of the first epoch observation for 36 sources, including 35 VLBI images of the methanol maser. Since two independent sources were found in three images, images of 38 sources were obtained. In 34 sources, 10 or more spots were detected. The observed spatial scale of the maser distribution was from 9 to 4900 astronomical units, and the following morphological categories were observed: elliptical, arched, linear, paired, and complex. The position of the maser spot was determined with an accuracy of approximately 0.1 mas, which is sufficiently high to measure the internal proper motion from two years of monitoring observations. The VLBI observation, however, detected only approximately 20% of all maser emissions, suggesting that the remaining 80% of the total flux was spread into an undetectable extended distribution. Therefore, in addition to high-resolution observations, it is important to observe the whole structure of the maser emission including extended low-brightness structures, in order to reveal the associated site of the maser and gas motion.

  6. Observations of Leonid Meteors Using a Mid-Wave Infrared Imaging Spectrograph

    NASA Astrophysics Data System (ADS)

    Rossano, George S.; Russell, Ray W.; Lynch, David K.; Tessensohn, Ted K.; Warren, David; Jenniskens, Peter

    We report broadband 3-5.5 µm detections of two Leonid meteors observed during the 1998 Leonid Multi-Instrument Aircraft Campaign. Each meteor was detected at only one position along their trajectory just prior to the point of maximum light emission. We describe the particular aspects of the Aerospace Corp. Mid-wave Infra-Red Imaging Spectrograph (MIRIS) developed for the observation of short duration transient events that impact its ability to detect Leonid meteors. This instrument had its first deployment during the 1998 Leonid MAC. We infer from our observations that the mid-wave IR light curves of two Leonid meteors differed from the visible light curve. At the points of detection, the infrared emission in the MIRIS passband was 25 +/- 4 times that at optical wavelengths for both meteors. In addition, we find an upper limit of 800 K for the solid body temperature of the brighter meteor we observed, at the point in the trajectory where we made our mid-wave IR detection.

  7. Plasma Distribution in Mercury's Magnetosphere Derived from MESSENGER Magnetometer and Fast Imaging Plasma Spectrometer Observations

    NASA Technical Reports Server (NTRS)

    Korth, Haje; Anderson, Brian J.; Gershman, Daniel J.; Raines, Jim M.; Slavin, James A.; Zurbuchen, Thomas H.; Solomon, Sean C.; McNutt, Ralph L.

    2014-01-01

    We assess the statistical spatial distribution of plasma in Mercury's magnetosphere from observations of magnetic pressure deficits and plasma characteristics by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. The statistical distributions of proton flux and pressure were derived from 10months of Fast Imaging Plasma Spectrometer (FIPS) observations obtained during the orbital phase of the MESSENGER mission. The Magnetometer-derived pressure distributions compare favorably with those deduced from the FIPS observations at locations where depressions in the magnetic field associated with the presence of enhanced plasma pressures are discernible in the Magnetometer data. The magnitudes of the magnetic pressure deficit and the plasma pressure agree on average, although the two measures of plasma pressure may deviate for individual events by as much as a factor of approximately 3. The FIPS distributions provide better statistics in regions where the plasma is more tenuous and reveal an enhanced plasma population near the magnetopause flanks resulting from direct entry of magnetosheath plasma into the low-latitude boundary layer of the magnetosphere. The plasma observations also exhibit a pronounced north-south asymmetry on the nightside, with markedly lower fluxes at low altitudes in the northern hemisphere than at higher altitudes in the south on the same field line. This asymmetry is consistent with particle loss to the southern hemisphere surface during bounce motion in Mercury's offset dipole magnetic field.

  8. CHROMOSPHERIC AND CORONAL OBSERVATIONS OF SOLAR FLARES WITH THE HELIOSEISMIC AND MAGNETIC IMAGER

    SciTech Connect

    Martínez Oliveros, Juan-Carlos; Krucker, Säm; Hudson, Hugh S.; Saint-Hilaire, Pascal; Bain, Hazel; Lindsey, Charles; Bogart, Rick; Couvidat, Sebastien; Scherrer, Phil; Schou, Jesper

    2014-01-10

    We report observations of white-light ejecta in the low corona, for two X-class flares on 2013 May 13, using data from the Helioseismic and Magnetic Imager (HMI) of the Solar Dynamics Observatory. At least two distinct kinds of sources appeared (chromospheric and coronal), in the early and later phases of flare development, in addition to the white-light footpoint sources commonly observed in the lower atmosphere. The gradual emissions have a clear identification with the classical loop-prominence system, but are brighter than expected and possibly seen here in the continuum rather than line emission. We find the HMI flux exceeds the radio/X-ray interpolation of the bremsstrahlung produced in the flare soft X-ray sources by at least one order of magnitude. This implies the participation of cooler sources that can produce free-bound continua and possibly line emission detectable by HMI. One of the early sources dynamically resembles {sup c}oronal rain{sup ,} appearing at a maximum apparent height and moving toward the photosphere at an apparent constant projected speed of 134 ± 8 km s{sup –1}. Not much literature exists on the detection of optical continuum sources above the limb of the Sun by non-coronagraphic instruments and these observations have potential implications for our basic understanding of flare development, since visible observations can in principle provide high spatial and temporal resolution.

  9. Revised calibration for near- and mid-infrared images from ˜4000 pointed observations with AKARI/IRC

    NASA Astrophysics Data System (ADS)

    Egusa, Fumi; Usui, Fumihiko; Murata, Kazumi; Yamashita, Takuji; Yamamura, Issei; Onaka, Takashi

    2016-04-01

    The Japanese infrared astronomical satellite AKARI performed ˜4000 pointed observations for 16 months until the end of August 2007, when the telescope and instruments were cooled by liquid helium. Observation targets include solar system objects, Galactic objects, local galaxies, and galaxies at cosmological distances. We describe recent updates on calibration processes of near- and mid-infrared images taken by the Infrared Camera (IRC), which has nine photometric filters covering 2-27 μm continuously. Using the latest data reduction toolkit, we created calibrated and stacked images from each pointed observation. About 90% of the stacked images have a position accuracy better than 1{^''.}5. Uncertainties in aperture photometry estimated from a typical standard sky deviation of stacked images are a factor of ˜2-4 smaller than those of AllWISE at similar wavelengths. The processed images, together with documents such as process logs, as well as the latest toolkit are available online.

  10. A CMOS image sensor with stacked photodiodes for lensless observation system of digital enzyme-linked immunosorbent assay

    NASA Astrophysics Data System (ADS)

    Takehara, Hironari; Miyazawa, Kazuya; Noda, Toshihiko; Sasagawa, Kiyotaka; Tokuda, Takashi; Kim, Soo Hyeon; Iino, Ryota; Noji, Hiroyuki; Ohta, Jun

    2014-01-01

    A CMOS image sensor with stacked photodiodes was fabricated using 0.18 µm mixed signal CMOS process technology. Two photodiodes were stacked at the same position of each pixel of the CMOS image sensor. The stacked photodiodes consist of shallow high-concentration N-type layer (N+), P-type well (PW), deep N-type well (DNW), and P-type substrate (P-sub). PW and P-sub were shorted to ground. By monitoring the voltage of N+ and DNW individually, we can observe two monochromatic colors simultaneously without using any color filters. The CMOS image sensor is suitable for fluorescence imaging, especially contact imaging such as a lensless observation system of digital enzyme-linked immunosorbent assay (ELISA). Since the fluorescence increases with time in digital ELISA, it is possible to observe fluorescence accurately by calculating the difference from the initial relation between the pixel values for both photodiodes.

  11. Twin mesospheric bores observed over Brazilian equatorial region

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  12. Observations and temperatures of Io's Pele Patera from Cassini and Galileo spacecraft images

    USGS Publications Warehouse

    Radebaugh, J.; McEwen, A.S.; Milazzo, M.P.; Keszthelyi, L.P.; Davies, A.G.; Turtle, E.P.; Dawson, D.D.

    2004-01-01

    Pele has been the most intense high-temperature hotspot on Io to be continuously active during the Galileo monitoring from 1996-2001. A suite of characteristics suggests that Pele is an active lava lake inside a volcanic depression. In 2000-2001, Pele was observed by two spacecraft, Cassini and Galileo. The Cassini observations revealed that Pele is variable in activity over timescales of minutes, typical of active lava lakes in Hawaii and Ethiopia. These observations also revealed that the short-wavelength thermal emission from Pele decreases with rotation of Io by a factor significantly greater than the cosine of the emission angle, and that the color temperature becomes more variable and hotter at high emission angles. This behavior suggests that a significant portion of the visible thermal emission from Pele comes from lava fountains within a topographically confined lava body. High spatial resolution, nightside images from a Galileo flyby in October 2001 revealed a large, relatively cool (< 800 K) region, ringed by bright hotspots, and a central region of high thermal emission, which is hypothesized to be due to fountaining and convection in the lava lake. Images taken through different filters revealed color temperatures of 1500 ?? 80 K from Cassini ISS data and 1605 ?? 220 and 1420 ?? 100 K from small portions of Galileo SSI data. Such temperatures are near the upper limit for basaltic compositions. Given the limitations of deriving lava eruption temperature in the absence of in situ measurement, it is possible that Pele has lavas with ultramafic compositions. The long-lived, vigorous activity of what is most likely an actively overturning lava lake in Pele Patera indicates that there is a strong connection to a large, stable magma source region. ?? 2003 Elsevier Inc. All rights reserved.

  13. A method for determining the drift velocity of plasma depletions in the equatorial ionosphere using far-ultraviolet spacecraft observations

    NASA Astrophysics Data System (ADS)

    Park, S. H.; England, S. L.; Immel, T. J.; Frey, H. U.; Mende, S. B.

    2007-11-01

    The Far-Ultraviolet Imager (IMAGE-FUV) on board the NASA IMAGE satellite has been used to observe plasma depletions in the nightside equatorial ionosphere. Observations from periods around spacecraft apogee, during which equatorial regions are visible for several hours, have allowed the velocity of these plasma depletions to be d