WorldWideScience

Sample records for diurnal photometric variability

  1. Characterization of extrasolar terrestrial planets from diurnal photometric variability.

    Science.gov (United States)

    Ford, E B; Seager, S; Turner, E L

    2001-08-30

    The detection of massive planets orbiting nearby stars has become almost routine, but current techniques are as yet unable to detect terrestrial planets with masses comparable to the Earth's. Future space-based observatories to detect Earth-like planets are being planned. Terrestrial planets orbiting in the habitable zones of stars-where planetary surface conditions are compatible with the presence of liquid water-are of enormous interest because they might have global environments similar to Earth's and even harbour life. The light scattered by such a planet will vary in intensity and colour as the planet rotates; the resulting light curve will contain information about the planet's surface and atmospheric properties. Here we report a model that predicts features that should be discernible in the light curve obtained by low-precision photometry. For extrasolar planets similar to Earth, we expect daily flux variations of up to hundreds of per cent, depending sensitively on ice and cloud cover as well as seasonal variations. This suggests that the meteorological variability, composition of the surface (for example, ocean versus land fraction) and rotation period of an Earth-like planet could be derived from photometric observations. Even signatures of Earth-like plant life could be constrained or possibly, with further study, even uniquely determined.

  2. Photometric Variability in Earthshine Observations

    OpenAIRE

    Langford, Sally V.; Wyithe, J. Stuart B.; Turner, Edwin L.

    2009-01-01

    The identification of an extrasolar planet as Earth-like will depend on the detection of atmospheric signatures or surface non-uniformities. In this paper we present spatially unresolved flux light curves of Earth for the purpose of studying a prototype extrasolar terrestrial planet. Our monitoring of the photometric variability of earthshine revealed changes of up to 23 % per hour in the brightness of Earth's scattered light at around 600 nm, due to the removal of specular reflection from th...

  3. Photometric Variability of the Be Star Population

    CERN Document Server

    Labadie-Bartz, Jonathan; McSwain, M Virginia; Bjorkman, J E; Bjorkman, K S; Lund, Michael B; Rodriguez, Joseph E; Stassun, Keivan G; Stevens, Daniel J; Gaudi, B Scott; James, David J; Kuhn, Rudolf B; Siverd, Robert J; Beatty, Thomas G

    2016-01-01

    Be stars have generally been characterized by the emission lines in their spectra, and especially the time variability of those spectroscopic features. They are known to also exhibit photometric variability at multiple timescales, but have not been broadly compared and analyzed by that behavior. We have taken advantage of the advent of wide-field, long-baseline, and high-cadence photometric surveys that search for transiting exoplanets to perform a comprehensive analysis of brightness variations among a large number of known Be stars. The photometric data comes from the KELT transit survey, with a typical cadence of 30 minutes, baseline of up to ten years, photometric precision of about 1%, and coverage of about 60% of the sky. We analyze KELT light curves of 610 known Be stars in both the Northern and Southern hemispheres in an effort to study their variability. Consistent with other studies of Be star variability, we find most of the stars to be photometrically variable. We derive lower limits on the fracti...

  4. Photometric Variability of Four Coronally Active Stars

    Indian Academy of Sciences (India)

    J. C. Pandey; K. P. Singh; R. Sagar; S. A. Drake

    2002-03-01

    We present photometric observations of four stars that are optical counterparts of soft X-ray/EUV sources, namely 1ES 0829+15.9, 1ES0920-13.6, 2RE J110159+223509 and 1ES 1737+61.2. We have discovered periodic variability in two of the stars, viz., MCC 527 (1ES 0829+15.9; Period = 0.828 ± 0.0047) and HD 81032 (1ES 0920-13.6; Period = ∼ 57.02 ± 0.560 days). HD 95559 (2RE J110159+223509) is found to show a period of 3. HD 160934 (1ES1737+61.2) also shows photometric variability but needs to be monitored further for finding its period. These stars most likely belong to the class of chromospherically active stars.

  5. Photometric monitoring of Luminous Blue Variables

    CERN Document Server

    Buemi, Carla; Leto, Paolo; Schilliro', Francesco; Trigilio, Corrado; Umana, Grazia; Bernabei, Stefano; Cutispoto, Giuseppe; Messina, Sergio

    2010-01-01

    We present some preliminary results from our program of intensive near-infrared photometric monitoring of a sample of confirmed and candidate Luminous Blue Variables (LBVs) conducted from 2008 to 2010. Clear long-term variability has been observed for Wray 17-96 and V481 Sct, with overall brightness variation greater than 1 mag in the J band. Other sources, such as LBV 1806-20 showed detectable variability with amplitudes of few tenths of a magnitude with time-scale of about 60 days.

  6. Photometric monitoring of Luminous Blue Variables

    Science.gov (United States)

    Buemi, Carla; Distefano, Elisa; Leto, Paolo; Schillirò, Francesco; Trigilio, Corrado; Umana, Grazia; Bernabei, Stefano; Cutispoto, Giuseppe; Messina, Sergio

    2011-01-01

    We present some preliminary results from our program of intensive near-infrared photometric monitoring of a sample of confirmed and candidate Luminous Blue Variables (LBVs) conducted from 2008 to 2010. Clear long-term variability has been observed for Wray 17-96 and V481 Sct, with overall brightness variation greater than 1 mag in the J band. Other sources, such as LBV 1806-20 showed detectable variability with amplitudes of few tenths of a magnitude with a time-scale of about 60 days.

  7. The unusual photometric variability of the PMS star GM Cep

    CERN Document Server

    Semkov, E; Peneva, S; Milanov, T; Stoyanov, K; Stateva, I; Kjurkchieva, D; Dimitrov, D; Radeva, V

    2015-01-01

    Results from UBVRI photometric observations of the pre-main sequence star GM Cep obtained in the period April 2011 - August 2014 are reported in the paper. Presented data are a continuation of our photometric monitoring of the star started in 2008. GM Cep is located in the field of the young open cluster Trumpler 37 and over the past years it has been an object of intense photometric and spectral studies. The star shows a strong photometric variability interpreted as a possible outburst from EXor type in previous studies. Our photometric data for a period of over six years show a large amplitude variability (Delta V ~ 2.3 mag.) and several deep minimums in brightness are observed. The analysis of the collected multicolor photometric data shows the typical of UX Ori variables a color reversal during the minimums in brightness. The observed decreases in brightness have a different shape, and evidences of periodicity are not detected. At the same time, high amplitude rapid variations in brightness typical for th...

  8. The Unusual Photometric Variability of the PMS Star GM Cep

    Science.gov (United States)

    Semkov, E. H.; Ibryamov, S. I.; Peneva, S. P.; Milanov, T. R.; Stoyanov, K. A.; Stateva, I. K.; Kjurkchieva, D. P.; Dimitrov, D. P.; Radeva, V. S.

    2015-03-01

    Results from UBVRI photometric observations of the pre-main sequence star GM Cep obtained in the period 2011 April-2014 August are reported in the paper. Presented data are a continuation of our photometric monitoring of the star started in 2008. GM Cep is located in the field of the young open cluster Trumpler 37 and over the past years it has been an object of intense photometric and spectral studies. The star shows a strong photometric variability interpreted as a possible outburst from EXor type in previous studies. Our photometric data for a period of over six years show a large amplitude variability (ΔV ~ 2.3 mag) and several deep minimums in brightness are observed. The analysis of the collected multicolour photometric data show the typical of UX Ori variables a colour reversal during the minimums in brightness. The observed decreases in brightness have a different shape, and evidences of periodicity are not detected. At the same time, high amplitude rapid variations in brightness typical for the classical T Tauri stars also present on the light curve of GM Cep. The spectrum of GM Cep shows the typical of classical T Tauri stars wide Hα emission line and absorption lines of some metals. We calculate the outer radius of the Hα emitting region as 10.4 ± 0.5 R⊙ and the accretion rate as 1.8 × 10- 7 M⊙ yr- 1.

  9. Quasar Selection Based on Photometric Variability

    CERN Document Server

    MacLeod, C L; Ivezic, Z; Kochanek, C S; Gibson, R; Meisner, A; Kozlowski, S; Sesar, B; Becker, A C; de Vries, W

    2010-01-01

    We develop a method for separating quasars from other variable point sources using SDSS Stripe 82 light curve data for ~10,000 variable objects. To statistically describe quasar variability, we use a damped random walk model parametrized by a damping time scale, tau, and an asymptotic amplitude (structure function), SF_inf. With the aid of an SDSS spectroscopically confirmed quasar sample, we demonstrate that variability selection in typical extragalactic fields with low stellar density can deliver complete samples with reasonable purity (or efficiency, E). Compared to a selection method based solely on the slope of the structure function, the inclusion of the tau information boosts E from 60% to 75% while maintaining a highly complete sample (98%) even in the absence of color information. For a completeness of C=90%, E is boosted from 80% to 85%. Conversely, C improves from 90% to 97% while maintaining E=80% when imposing a lower limit on tau. With the aid of color selection, the purity can be further booste...

  10. Investigating the Spectroscopic Variability and Magnetic Activity of Photometrically Variable M Dwarfs in SDSS

    Science.gov (United States)

    Ventura, Jean-Paul; Cid, Aurora; Schmidt, Sarah J.; Rice, Emily L.; Cruz, Kelle L.

    2017-01-01

    Magnetic activity, a wide range of observable phenomena produced in the outer atmospheres of stars, is currently not well understood for M dwarfs. In higher mass stars, magnetic activity is powered by a dynamo process involving the differential rotation of a star’s inner regions. This process generates a magnetic field, heats up regions in the atmosphere, and produces emission line radiation (H-alpha) from collisional excitation. Using the Sloan Digital Sky Survey’s (SDSS) Time Domain Spectroscopic Survey (TDSS), we will compare the H-alpha emission line strengths for a sample of 12,000 known photometrically variable M dwarfs observed in the PAN-STARRS1 survey with those of a known non-variable sample. This will be done in order to test whether photometric variability of the sample correlate with chromospheric H-alpha emission features and if not, explore the alternate reasons for that photometric variability, like binarity.

  11. Deep greedy learning under thermal variability in full diurnal cycles

    Science.gov (United States)

    Rauss, Patrick; Rosario, Dalton

    2017-08-01

    We study the generalization and scalability behavior of a deep belief network (DBN) applied to a challenging long-wave infrared hyperspectral dataset, consisting of radiance from several manmade and natural materials within a fixed site located 500 m from an observation tower. The collections cover multiple full diurnal cycles and include different atmospheric conditions. Using complementary priors, a DBN uses a greedy algorithm that can learn deep, directed belief networks one layer at a time and has two layers form to provide undirected associative memory. The greedy algorithm initializes a slower learning procedure, which fine-tunes the weights, using a contrastive version of the wake-sleep algorithm. After fine-tuning, a network with three hidden layers forms a very good generative model of the joint distribution of spectral data and their labels, despite significant data variability between and within classes due to environmental and temperature variation occurring within and between full diurnal cycles. We argue, however, that more questions than answers are raised regarding the generalization capacity of these deep nets through experiments aimed at investigating their training and augmented learning behavior.

  12. Classical variables in the era of space photometric missions

    Directory of Open Access Journals (Sweden)

    Molnár L.

    2015-01-01

    Full Text Available The space photometric missions like CoRoT and Kepler transformed our view of pulsating stars, including the well-known RR Lyrae and Cepheid classes. The K2, TESS and PLATO missions will expand these investigations to larger sample sizes and to specific stellar populations.

  13. Sensitivity of Amazonian TOA flux diurnal cycle composite monthly variability to choice of reanalysis

    Science.gov (United States)

    Dodson, J. Brant; Taylor, Patrick C.

    2016-05-01

    Amazonian deep convection experiences a strong diurnal cycle driven by the cycle in surface sensible heat flux, which contributes to a significant diurnal cycle in the top of the atmosphere (TOA) radiative flux. Even when accounting for seasonal variability, the TOA flux diurnal cycle varies significantly on the monthly timescale. Previous work shows evidence supporting a connection between variability in the convective and radiative cycles, likely modulated by variability in monthly atmospheric state (e.g., convective instability). The hypothesized relationships are further investigated with regression analysis of the radiative diurnal cycle and atmospheric state using additional meteorological variables representing convective instability and upper tropospheric humidity. The results are recalculated with three different reanalyses to test the reliability of the results. The radiative diurnal cycle sensitivity to upper tropospheric humidity is about equal in magnitude to that of convective instability. In addition, the results are recalculated with the data subdivided into the wet and dry seasons. Overall, clear-sky radiative effects have a dominant role in radiative diurnal cycle variability during the dry season. Because of this, even in a convectively active region, the clear-sky radiative effects must be accounted for in order to fully explain the monthly variability in diurnal cycle. Finally, while there is general agreement between the different reanalysis-based results when examining the full data time domain (without regard to time of year), there are significant disagreements when the data are divided into wet and dry seasons. The questionable reliability of reanalysis data is a major limitation.

  14. SST Diurnal Variability: Regional Extent & Implications in Atmospheric Modelling

    DEFF Research Database (Denmark)

    Karagali, Ioanna; Høyer, Jacob L.

    2013-01-01

    and quantify regional diurnal warming from the experimental MSG/SEVIRI hourly SST fields, for the period 2006-2012. ii) To investigate the impact of the increased SST temporal resolution in the atmospheric model WRF, in terms of modeled 10-m winds and surface heat fluxes. Withing this context, 3 main tasks...... regional diurnal warming over the SEVIRI disk, a SEVIRI derived reference field representative of the well mixed night-time conditions is required. Different methodologies are tested and the results are validated against SEVIRI pre-dawn SSTs and in situ data from moored and drifting buoys....

  15. Variability in diurnal testosterone, exposure to violence, and antisocial behavior in young adolescents.

    Science.gov (United States)

    Peckins, Melissa K; Susman, Elizabeth J

    2015-11-01

    The purpose of this report is to provide evidence of an association between within-person variability in diurnal testosterone over 1 year, lifetime exposure to violence, and the manifestation of antisocial behavior in 135 pubertal-aged adolescents across 1 year. Adolescents' sex and lifetime history of violence exposure moderated the association between within-person variability in diurnal testosterone and antisocial behavior. Furthermore, sex-stratified analyses revealed that lifetime history of exposure to violence moderated the association between within-person variability in diurnal testosterone and antisocial behavior in females only. This report is unique in that it illuminates sex differences in within-person associations among exposure to violence, individual variability in diurnal testosterone, and antisocial behavior.

  16. Seasonal and diurnal variability of thermal structure in the coastal waters off Visakhapatnam

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, B.P.; RameshBabu, V.; Chandramohan, P.

    Seasonal and diurnal variability of thermal structure in the coastal waters off Visakhapatnam has been examined in relation to the flow field and surface winds utilizing the hourly data of temperature and currents taken at a fixed location over a...

  17. Comparative performance of selected variability detection techniques in photometric time series data

    CERN Document Server

    Sokolovsky, K V; Karampelas, A; Antipin, S V; Bellas-Velidis, I; Benni, P; Bonanos, A Z; Burdanov, A Y; Derlopa, S; Hatzidimitriou, D; Khokhryakova, A D; Kolesnikova, D M; Korotkiy, S A; Lapukhin, E G; Moretti, M I; Popov, A A; Pouliasis, E; Samus, N N; Spetsieri, Z; Veselkov, S A; Volkov, K V; Yang, M; Zubareva, A M

    2016-01-01

    Photometric measurements are prone to systematic errors presenting a challenge to low-amplitude variability detection. In search for a general-purpose variability detection technique able to recover a broad range of variability types including currently unknown ones, we test 18 statistical characteristics quantifying scatter and/or correlation between brightness measurements. We compare their performance in identifying variable objects in seven time-series datasets obtained with telescopes ranging in size from a telephoto lens to 1m-class and probing variability on timescales from minutes to decades. The test datasets together include lightcurves of 127539 objects, among them 1251 variable stars of various types and represent a range of observing conditions often found in ground-based variability surveys. The real data are complemented by simulations. We propose a combination of two indices that together recover a broad range of variability types from photometric data characterized by a wide variety of sampli...

  18. Comparative performance of selected variability detection techniques in photometric time series data

    Science.gov (United States)

    Sokolovsky, K. V.; Gavras, P.; Karampelas, A.; Antipin, S. V.; Bellas-Velidis, I.; Benni, P.; Bonanos, A. Z.; Burdanov, A. Y.; Derlopa, S.; Hatzidimitriou, D.; Khokhryakova, A. D.; Kolesnikova, D. M.; Korotkiy, S. A.; Lapukhin, E. G.; Moretti, M. I.; Popov, A. A.; Pouliasis, E.; Samus, N. N.; Spetsieri, Z.; Veselkov, S. A.; Volkov, K. V.; Yang, M.; Zubareva, A. M.

    2017-01-01

    Photometric measurements are prone to systematic errors presenting a challenge to low-amplitude variability detection. In search for a general-purpose variability detection technique able to recover a broad range of variability types including currently unknown ones, we test 18 statistical characteristics quantifying scatter and/or correlation between brightness measurements. We compare their performance in identifying variable objects in seven time series data sets obtained with telescopes ranging in size from a telephoto lens to 1 m-class and probing variability on time-scales from minutes to decades. The test data sets together include light curves of 127 539 objects, among them 1251 variable stars of various types and represent a range of observing conditions often found in ground-based variability surveys. The real data are complemented by simulations. We propose a combination of two indices that together recover a broad range of variability types from photometric data characterized by a wide variety of sampling patterns, photometric accuracies and percentages of outlier measurements. The first index is the interquartile range (IQR) of magnitude measurements, sensitive to variability irrespective of a time-scale and resistant to outliers. It can be complemented by the ratio of the light-curve variance to the mean square successive difference, 1/η, which is efficient in detecting variability on time-scales longer than the typical time interval between observations. Variable objects have larger 1/η and/or IQR values than non-variable objects of similar brightness. Another approach to variability detection is to combine many variability indices using principal component analysis. We present 124 previously unknown variable stars found in the test data.

  19. Comparative performance of selected variability detection techniques in photometric time series data

    Science.gov (United States)

    Sokolovsky, K. V.; Gavras, P.; Karampelas, A.; Antipin, S. V.; Bellas-Velidis, I.; Benni, P.; Bonanos, A. Z.; Burdanov, A. Y.; Derlopa, S.; Hatzidimitriou, D.; Khokhryakova, A. D.; Kolesnikova, D. M.; Korotkiy, S. A.; Lapukhin, E. G.; Moretti, M. I.; Popov, A. A.; Pouliasis, E.; Samus, N. N.; Spetsieri, Z.; Veselkov, S. A.; Volkov, K. V.; Yang, M.; Zubareva, A. M.

    2016-09-01

    Photometric measurements are prone to systematic errors presenting a challenge to low-amplitude variability detection. In search for a general-purpose variability detection technique able to recover a broad range of variability types including currently unknown ones, we test 18 statistical characteristics quantifying scatter and/or correlation between brightness measurements. We compare their performance in identifying variable objects in seven time-series datasets obtained with telescopes ranging in size from a telephoto lens to 1 m-class and probing variability on timescales from minutes to decades. The test datasets together include lightcurves of 127539 objects, among them 1251 variable stars of various types and represent a range of observing conditions often found in ground-based variability surveys. The real data are complemented by simulations. We propose a combination of two indices that together recover a broad range of variability types from photometric data characterized by a wide variety of sampling patterns, photometric accuracies, and percentages of outlier measurements. The first index is the interquartile range (IQR) of magnitude measurements, sensitive to variability irrespective of a timescale and resistant to outliers. It can be complemented by the ratio of the lightcurve variance to the mean square successive difference, 1/η, which is efficient in detecting variability on timescales longer than the typical time interval between observations. Variable objects have larger 1/η and/or IQR values than non-variable objects of similar brightness. Another approach to variability detection is to combine many variability indices using principal component analysis. We present 124 previously unknown variable stars found in the test data.

  20. Photometric Variability in the CSTAR Field: Results from the 2008 Data Set

    Science.gov (United States)

    Wang, Songhu; Zhang, Hui; Zhou, Xu; Zhou, Ji-Lin; Fu, Jian-Ning; Yang, Ming; Liu, Huigen; Xie, Jiwei; Wang, Lifan; Wang, Lingzhi; Wittenmyer, R. A.; Ashley, M. C. B.; Feng, Long-Long; Gong, Xuefei; Lawrence, J. S.; Liu, Qiang; Luong-Van, D. M.; Ma, Jun; Peng, Xiyan; Storey, J. W. V.; Wu, Zhenyu; Yan, Jun; Yang, Huigen; Yang, Ji; Yuan, Xiangyan; Zhang, Tianmeng; Zhang, Xiaojia; Zhu, Zhenxi; Zou, Hu

    2015-06-01

    The Chinese Small Telescope Array (CSTAR) is the first telescope facility built at Dome A, Antarctica. During the 2008 observing season, the installation provided long-baseline and high-cadence photometric observations in the i-band for 18,145 targets within 20 {{deg }2} CSTAR field around the South Celestial Pole for the purpose of monitoring the astronomical observing quality of Dome A and detecting various types of photometric variability. Using sensitive and robust detection methods, we discover 274 potential variables from this data set, 83 of which are new discoveries. We characterize most of them, providing the periods, amplitudes, and classes of variability. The catalog of all these variables is presented along with the discussion of their statistical properties.

  1. Detection of Low-Amplitude Photometric Variability of Magnetic White Dwarfs

    Science.gov (United States)

    Valeev, A. F.; Antonyuk, K. A.; Pit, N. V.; Moskvitin, A. S.; Grauzhanina, A. O.; Gadelshin, D. R.; Kolesnikov, S. V.; Burlakova, T. E.; Galazutdinov, G. A.; Gutaev, A. G.; Zhuchkov, R. Ya.; Ikhsanova, A. I.; Joshi, A.; Pandey, J. C.; Zhuzhulina, E. A.; Valyavin, G. G.

    2017-06-01

    We present the results of the ongoing photometric survey of magnetic white dwarfs. Variability of fluxes from WD 0009+501, GD 229, GRW+70°8247, and GD 56 has been detected. The detected variability of GD 356 is specially discussed. In case of GRW+70°8247 the V-band photometric variability amplitude is about 0fm04, the most probable period is from days to several tens of days. The degenerate GD 229 demonstrates the amplitude of the flux variation of about 0fm05 with a period between 10 and 20 days. In both cases the variability is most likely associated with rotation of these stars. These findings contradict with an idea on the existence of a special class of strong-magnetic very slowly rotating white dwarfs, the periods of which are estimated to have tens or even hundreds of years.

  2. Photometric Variability in the CSTAR Field: Results From the 2008 Data Set

    CERN Document Server

    Wang, Songhu; Zhou, Xu; Zhou, Ji-Lin; Fu, Jian-Ning; Yang, Ming; Liu, Huigen; Xie, Jiwei; Wang, Lifan; Wang, Lingzhi; Wittenmyer, R A; Ashley, M C B; Feng, Long-Long; Gong, Xuefei; Lawrence, J S; Liu, Qiang; Luong-Van, D M; Ma, Jun; Peng, Xiyan; Storey, J W V; Wu, Zhenyu; Yan, Jun; Yang, Huigen; Yang, Ji; Yuan, Xiangyan; Zhang, Tianmeng; Zhang, Xiaojia; Zhu, Zhenxi; Zou, Hu

    2015-01-01

    The Chinese Small Telescope ARray (CSTAR) is the first telescope facility built at Dome A, Antarctica. During the 2008 observing season, the installation provided long-baseline and high-cadence photometric observations in the i-band for 18,145 targets within 20 deg2 CSTAR field around the South Celestial Pole for the purpose of monitoring the astronomical observing quality of Dome A and detecting various types of photometric variability. Using sensitive and robust detection methods, we discover 274 potential variables from this data set, 83 of which are new discoveries. We characterize most of them, providing the periods, amplitudes and classes of variability. The catalog of all these variables is presented along with the discussion of their statistical properties.

  3. A study of the photometric variability of the peculiar magnetic white dwarf WD1953-011

    CERN Document Server

    Valyavin, G; Plachinda, S; Clark, D M; Wade, G A; Machado, L Fox; Alvarez, M; Lopez, J M; Hiriart, D; Han, Inwoo; Jeon, Young-Beom; Bagnulo, S; Zharikov, S V; Zurita, C; Mujica, R; Shulyak, D; Burlakova, T

    2011-01-01

    We present and interpret simultaneous new photometric and spectroscopic observations of the peculiar magnetic white dwarf WD1953-011. The flux in the V-band filter and intensity of the Balmer spectral lines demonstrate variability with the rotation period of about 1.45 days. According to previous studies, this variability can be explained by the presence of a dark spot having a magnetic nature, analogous to a sunspot. Motivated by this idea, we examine possible physical relationships between the suggested dark spot and the strong-field magnetic structure (magnetic "spot", or "tube") recently identified on the surface of this star. Comparing the rotationally-modulated flux with the variable spectral observables related to the magnetic "spot" we establish their correlation, and therefore their physical relationship. Modeling the variable photometric flux assuming that it is associated with temperature variations in the stellar photosphere, we argue that the strong-field area and dark, low-temperature spot are c...

  4. Diurnal variability in orthostatic tachycardia: implications for the postural tachycardia syndrome.

    Science.gov (United States)

    Brewster, Jordan A; Garland, Emily M; Biaggioni, Italo; Black, Bonnie K; Ling, John F; Shibao, Cyndya A; Robertson, David; Raj, Satish R

    2012-01-01

    Patients with POTS (postural tachycardia syndrome) have excessive orthostatic tachycardia (>30 beats/min) when standing from a supine position. HR (heart rate) and BP (blood pressure) are known to exhibit diurnal variability, but the role of diurnal variability in orthostatic changes of HR and BP is not known. In the present study, we tested the hypothesis that there is diurnal variation of orthostatic HR and BP in patients with POTS and healthy controls. Patients with POTS (n=54) and healthy volunteers (n=26) were admitted to the Clinical Research Center. Supine and standing (5 min) HR and BP were obtained in the evening on the day of admission and in the following morning. Overall, standing HR was significantly higher in the morning (102±3 beats/min) than in the evening (93±2 beats/min; Porthostatic BP in POTS. A greater number of subjects met the POTS HR criterion in the morning compared with the evening (P=0.008). There was significant diurnal variability in orthostatic tachycardia, with a great orthostatic tachycardia in the morning compared with the evening in both patients with POTS and healthy subjects. Given the importance of orthostatic tachycardia in diagnosing POTS, this diurnal variability should be considered in the clinic as it may affect the diagnosis of POTS.

  5. Photometric variability of the Herbig Ae star HD 37806

    CERN Document Server

    Rucinski, S M; Hareter, M; Pojmanski, G; Kuschnig, R; Matthews, J M; Guenther, D B; Moffat, A F J; Sasselov, D; Weiss, W W

    2010-01-01

    The more massive counterparts of T Tauri stars, Herbig Ae/Be stars, are known to vary in a complex way with no variability mechanism clearly identified. We attempt to characterize the optical variability of HD~37806 (MWC 120) on time scales ranging between minutes and several years. A continuous, one-minute resolution, 21 day-long sequence of MOST (Microvariability & Oscillations of STars) satellite observations has been analyzed using wavelet, scalegram and dispersion analysis tools. The MOST data have been augmented by sparse observations over 9 seasons from ASAS (All Sky Automated Survey), by previously non-analyzed ESO (European Southern Observatory) data partly covering 3 seasons and by archival measurements dating back half a century ago. Mutually superimposed flares or accretion instabilities grow in size from about 0.0003 of the mean flux on a time scale of minutes to a peak-to-peak range of <~0.05 on a time scale of a few years. The resulting variability has properties of stochastic "red" nois...

  6. Understanding the photometric variability of {\\zeta} Ori Aa

    CERN Document Server

    Buysschaert, B; Ramiaramanantsoa, T; Richardson, N D; David-Uraz, A; Moffat, A F J

    2016-01-01

    We studied the variability of the magnetic O-type supergiant $\\zeta$ Ori Aa using multi-colour BRITE photometry. We confirmed the known rotation frequency $f_{\\rm rot} = 0.15 \\pm 0.02$ c/d, and detected some of its higher harmonics, of which $4f_{\\rm rot}$ is compatible with the known DAC recurrence timescale. Thanks to simultaneous high-resolution CHIRON spectroscopy, we could identify another frequency $f_{\\rm env} = 0.10 \\pm 0.02$ c/d, caused by the circumstellar environment. Variations in the circumstellar environment are believed to cause the observed difference between the BRITE lightcurves.

  7. The variability of Sun-like stars: reproducing observed photometric trends

    CERN Document Server

    Shapiro, A I; Krivova, N A; Schmutz, W K; Ball, W T; Knaack, R; Rozanov, E V; Unruh, Y C

    2014-01-01

    The Sun and stars with low magnetic activity levels, become photometrically brighter when their activity increases. Magnetically more active stars display the opposite behaviour and get fainter when their activity increases. We reproduce the observed photometric trends in stellar variations with a model that treats stars as hypothetical Suns with coverage by magnetic features different from that of the Sun. The presented model attributes the variability of stellar spectra to the imbalance between the contributions from different components of the solar atmosphere, such as dark starspots and bright faculae. A stellar spectrum is calculated from spectra of the individual components, by weighting them with corresponding disc area coverages. The latter are obtained by extrapolating the solar dependences of spot and facular disc area coverages on chromospheric activity to stars with different levels of mean chromospheric activity. We have found that the contribution by starspots to the variability increases faster...

  8. Diurnal variability of surface fluxes at an oceanic station in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Sarma, Y.V.B.; Rao, D.P.

    Diurnal variability of the surface fluxes and ocean heat content was studied using the time-series data on marine surface meteorological parameters and upper ocean temperature collected at an oceanic station in the Bay of Bengal during 1st to 8th...

  9. Discovery and Photometric Analysis of the ? Scuti Variable TYC 2168-132-1

    Science.gov (United States)

    Joner, M. D.; Hintz, E. G.; Corfini, G.

    2016-12-01

    Abstract We detail the discovery of the short-period variable star presently known as TYC 2168-132-1. We have examined four nights of photometric observations of this star secured in 2015 and find it to be a delta Scuti variable with a primary period of 0.0737523 days. The star is multiperiodic with three dominant frequencies at 13.556, 7.047, and 11.757 cycles/day. Evidence from light curve morphology supports the delta Scuti classification. We estimate intrinsic values for color and luminosity that place TYC 2168-132-1 within the lower part of the instability strip.

  10. Impact of photometric variability on age and mass determination in young stellar objects: the case of the Orion Nebula Cluster

    Science.gov (United States)

    Messina, Sergio; Parihar, Padmakar; Distefano, Elisa

    2017-03-01

    Very young stars, like the Orion Nebula Cluster (ONC) members analysed in the present study, exhibit photometric variability with a wide range of amplitudes. Such a prominent variability reflects in the inferred values of stellar colours and luminosities and, in turn, in the inferred stellar ages and masses. In this study, we measure the amplitudes of the photometric variability in V, R and I optical bands of a sample of 346 ONC members. We use these measurements to investigate how this variability affects the inferred masses and ages and whether it alone can account for the age spread among ONC members reported by earlier studies. We make use of colour-magnitude and Hertzprung-Russell (HR) diagrams. We find that members that show periodic and smooth photometric rotational modulation have masses and ages that are unaffected by variability when theoretical isochrones and evolutionary mass tracks are used in either colour-magnitude or HR diagrams. On the other hand, members with periodic but very scattered photometric rotational modulation and non-periodic members have masses and ages that are significantly affected. Moreover, using HR diagrams, we find that the observed I-band photometric variability can take account of only a fraction (˜50 per cent) of the inferred age spread, whereas the V-band photometric variability is large enough to mask any age spread.

  11. Diurnal Variability in the Martian Atmosphere Inferred from Nearly Coincident Profiles at Semidiurnal Separation

    Science.gov (United States)

    Heavens, N. G.; Johnson, M. S.

    2013-12-01

    Long-term monitoring of the Martian atmosphere by mapping instruments on sun-synchronous polar orbiters with slight orbital inclinations has two underutilized advantages for studying diurnal variability in atmospheric structure. First, the orbital pattern implies that the nightside orbit will be followed ~ 12 hours later by a dayside orbit that intersects it. That dayside orbit will be followed by a nightside orbit that itself intersects the dayside orbit ~ 12 hours previously at another point. These intersection points mostly occur in the tropics. At the poles, orbit convergence produces a similar effect, such that these semidiurnally separated orbits will have a number of nearly coincident observations in space that sample diurnal change in time. For limb sounders like the Mars Climate Sounder on Mars Reconnaissance Orbiter (MRO-MCS), the horizontal resolution of the instrument at the limb may be comparable to the spatial separation between portions of sequentially intersecting dayside/nightside orbits. Indeed, this width (if simultaneously iterated) would resolve wavenumber 100 structures at the Equator. In other words, the characteristics of the instrument and orbiter combine to allow local, semidiurnal sampling of the atmosphere at synoptic or greater scales. This can be helpful at resolving diurnal and perhaps longitudinal variability when retrievals are typically successful on the nightside at different longitudes than they are successful on the dayside. Second, long-term monitoring allows fortuiitous observation of useful examples of interannual variability in the behavior of the atmosphere. Here, we will present a study of diurnal variability in the vertical dust distribution and other aspects of the atmospheric structure of Mars that makes use of the observational advantages of MRO-MCS as well as the fortuitous occurrence of a Mars Year without significant regional or global dust storm activity: the year before the landing of the Mars Science Laboratory

  12. SPECTROSCOPIC AND PHOTOMETRIC VARIABILITY IN THE A0 SUPERGIANT HR 1040

    Energy Technology Data Exchange (ETDEWEB)

    Corliss, David J.; Morrison, Nancy D. [Department of Physics and Astronomy, The University of Toledo, Toledo, OH 43606 (United States); Adelman, Saul J., E-mail: david.corliss@wayne.edu [Department of Physics, The Citadel, 171 Moultrie Street, Charleston, SC 29409 (United States)

    2015-12-15

    A time-series analysis of spectroscopic and photometric observables of the A0 Ia supergiant HR 1040 has been performed, including equivalent widths, radial velocities, and Strömgren photometric indices. The data, obtained from 1993 through 2007, include 152 spectroscopic observations from the Ritter Observatory 1 m telescope and 269 Strömgren photometric observations from the Four College Automated Photoelectric Telescope. Typical of late B- and early A-type supergiants, HR 1040 has a highly variable Hα profile. The star was found to have an intermittent active phase marked by correlation between the Hα absorption equivalent width and blue-edge radial velocity and by photospheric connections observed in correlations to equivalent width, second moment and radial velocity in Si ii λλ6347, 6371. High-velocity absorption (HVA) events were observed only during this active phase. HVA events in the wind were preceded by photospheric activity, including Si ii radial velocity oscillations 19–42 days prior to onset of an HVA event and correlated increases in Si ii W{sub λ} and second moment from 13 to 23 days before the start of the HVA event. While increases in various line equivalent widths in the wind prior to HVA events have been reported in the past in other stars, our finding of precursors in enhanced radial velocity variations in the wind and at the photosphere is a new result.

  13. A search for photometric variability in magnetic chemically peculiar stars using ASAS-3 data

    Science.gov (United States)

    Bernhard, K.; Hümmerich, S.; Otero, S.; Paunzen, E.

    2015-09-01

    Context. The (magnetic) chemically peculiar (CP) stars of the upper main sequence are well-suited laboratories for investigating the influence of magnetic fields on the stellar surface because they produce abundance inhomogeneities (spots), which results in photometric variability that is explained in terms of the oblique rotator model. CP stars exhibiting this phenomenon are normally classified as α2 Canum Venaticorum (ACV) variables. It is important to increase the sample of known rotational periods among CP stars by discovering new ACV variables. An increased sample size will contribute to the understanding of the CP stars' evolution in time. Aims: We aim at discovering new ACV variables in the public data of the third phase of the All Sky Automated Survey (ASAS-3). Furthermore, by analysis of the available photometric data, we intend to derive rotational periods of the stars. Methods: The ASAS-3 data were cross-correlated with the Catalogue of Ap, HgMn, and Am stars in order to analyse the light curves of bona fide CP and related stars. The light curves were downloaded and cleaned of outliers and data points with a flag indicating bad quality. Promising candidates showing a larger scatter than observed for constant stars in the corresponding magnitude range were searched for periodic signals using a standard Fourier technique. Objects exhibiting periodic signals well above the noise level were considered and visually inspected, whereas borderline cases were rejected. Results: In total, we found 323 variables, from which 246 are reported here for the first time, and 77 were probably wrongly classified before. The observed variability pattern of most stars is in accordance with an ACV classification. For some cases, it is difficult to distinguish between the light curves of double-waved ACVs and the variability induced by orbital motion (ellipsoidal variables/eclipsing variables), especially for objects exhibiting very small amplitudes and/or significant scatter

  14. The complexity of diagnosing postural orthostatic tachycardia syndrome: influence of the diurnal variability.

    Science.gov (United States)

    Moon, Jangsup; Lee, Han Sang; Byun, Jung-Ick; Sunwoo, Jun-Sang; Shin, Jung-Won; Lim, Jung-Ah; Kim, Tae-Joon; Shin, Yong-Won; Lee, Keon-Joo; Jeon, Daejong; Jung, Keun-Hwa; Lee, Soon-Tae; Jung, Ki-Young; Chu, Kon; Lee, Sang Kun

    2016-03-01

    We investigated how the diagnosis of postural orthostatic tachycardia syndrome (POTS) would be changed due to diurnal variability in orthostatic tachycardia. The orthostatic vital sign test was administered to each patient twice, in the afternoon of the day of admission and the next morning (n = 113). Forty-six patients were diagnosed with POTS, and the remaining 67 patients were assigned to non-POTS group. Heart rate increments after standing were larger in the morning than in the afternoon in every group (all P orthostatic vital sign test. Orthostatic intolerance symptoms were provoked in only 45.7% of the POTS patients, more frequently in the morning. In conclusion, diurnal variability in hemodynamic parameters and provoked symptoms significantly challenged the diagnosis of POTS.

  15. Diurnal Variability of Turbidity Fronts Observed by Geostationary Satellite Ocean Color Remote Sensing

    Directory of Open Access Journals (Sweden)

    Zifeng Hu

    2016-02-01

    Full Text Available Monitoring front dynamics is essential for studying the ocean’s physical and biogeochemical processes. However, the diurnal displacement of fronts remains unclear because of limited in situ observations. Using the hourly satellite imageries from the Geostationary Ocean Color Imager (GOCI with a spatial resolution of 500 m, we investigated the diurnal displacement of turbidity fronts in both the northern Jiangsu shoal water (NJSW and the southwestern Korean coastal water (SKCW in the Yellow Sea (YS. The hourly turbidity fronts were retrieved from the GOCI-derived total suspended matter using the entropy-based algorithm. The results showed that the entropy-based algorithm could provide fine structure and clearly temporal evolution of turbidity fronts. Moreover, the diurnal displacement of turbidity fronts in NJSW can be up to 10.3 km in response to the onshore-offshore movements of tidal currents, much larger than it is in SKCW (around 4.7 km. The discrepancy between NJSW and SKCW are mainly caused by tidal current direction relative to the coastlines. Our results revealed the significant diurnal displacement of turbidity fronts, and highlighted the feasibility of using geostationary ocean color remote sensing technique to monitor the short-term frontal variability, which may contribute to understanding of the sediment dynamics and the coupling physical-biogeochemical processes.

  16. Exploring the Variable Sky with LINEAR. I. Photometric Recalibration with SDSS

    CERN Document Server

    Sesar, Branimir; Ivezić, Željko; Morgan, Dylan P; Becker, Andrew C; Wozniak, Przemyslaw

    2011-01-01

    We describe photometric recalibration of data obtained by the asteroid survey LINEAR. Although LINEAR was designed for astrometric discovery of moving objects, the dataset described here contains over 5 billion photometric measurements for about 25 million objects, mostly stars. We use SDSS data from the overlapping ~10,000 deg^2 of sky to recalibrate LINEAR photometry, and achieve errors of 0.03 mag for sources not limited by photon statistics, with errors of 0.2 mag at r~18. With its 200 observations per object on average, LINEAR data provide time domain information for the brightest 4 magnitudes of SDSS survey. At the same time, LINEAR extends the deepest similar wide-area variability survey, the Northern Sky Variability Survey, by 3 mag. We briefly discuss the properties of about 7,000 visually confirmed periodic variables, dominated by roughly equal fractions of RR Lyrae stars and eclipsing binary stars, and analyze their distribution in optical and infra-red color-color diagrams. The LINEAR dataset is p...

  17. EXPLORING THE VARIABLE SKY WITH LINEAR. I. PHOTOMETRIC RECALIBRATION WITH THE SLOAN DIGITAL SKY SURVEY

    Energy Technology Data Exchange (ETDEWEB)

    Sesar, Branimir [Division of Physics, Mathematics and Astronomy, Caltech, Pasadena, CA 91125 (United States); Stuart, J. Scott [Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, MA 02420-9108 (United States); Ivezic, Zeljko; Morgan, Dylan P.; Becker, Andrew C. [Department of Astronomy, University of Washington, Seattle, WA 98195-1580 (United States); Wozniak, Przemyslaw [Los Alamos National Laboratory, Los Alamos, NM 87545-0001 (United States)

    2011-12-15

    We describe photometric recalibration of data obtained by the asteroid survey LINEAR. Although LINEAR was designed for astrometric discovery of moving objects, the data set described here contains over 5 billion photometric measurements for about 25 million objects, mostly stars. We use Sloan Digital Sky Survey (SDSS) data from the overlapping {approx}10,000 deg{sup 2} of sky to recalibrate LINEAR photometry and achieve errors of 0.03 mag for sources not limited by photon statistics with errors of 0.2 mag at r {approx} 18. With its 200 observations per object on average, LINEAR data provide time domain information for the brightest four magnitudes of the SDSS survey. At the same time, LINEAR extends the deepest similar wide-area variability survey, the Northern Sky Variability Survey, by 3 mag. We briefly discuss the properties of about 7000 visually confirmed periodic variables, dominated by roughly equal fractions of RR Lyrae stars and eclipsing binary stars, and analyze their distribution in optical and infrared color-color diagrams. The LINEAR data set is publicly available from the SkyDOT Web site.

  18. Diurnal variability of heat fluxes over the coastal waters off Visakhapatnam during post-monsoon and winter seasons

    Digital Repository Service at National Institute of Oceanography (India)

    Ramu, Ch V.; Bharathi, G.; Sadhuram, Y.; Prasad, K.V.S.R.

    Diurnal variability of heat fluxes in the coastal waters of Visakhapatnam has been studied during post-monsoon (Oct, 2006) and winter (Jan-Feb, 2007) seasons utilizing the surface meteorological data and radiation measurements on-board CRV Sagar...

  19. Adventures in the World of Pulsating Variable Stars: Multisite Photometric Campaigns

    Science.gov (United States)

    Szabó, R.

    2004-06-01

    Advantages of photometric multisite campaigns are discussed, then published or prospective results of four - preceding and ongoing - observing runs are presented. Prospects and limits of photometric observations carried out from Hungary with small (~ 1m) telescopes are also outlined.

  20. Photometric and spectroscopic variability of the FUor star V582 Aurigae

    CERN Document Server

    Semkov, E H; Munari, U; Dennefeld, M; Mito, H; Dimitrov, D P; Ibryamov, S; Stoyanov, K A

    2013-01-01

    We carried out BVRI CCD photometric observations in the field of V582 Aur from 2009 August to 2013 February. We acquired high-, medium-, and low-resolution spectroscopy of V582 Aur during this period. To study the pre-outburst variability of the target and construct its historical light curve, we searched for archival observations in photographic plate collections. Both CCD and photographic observations were analyzed using a sequence of 14 stars in the field of V582 Aur calibrated in BVRI. The pre-outburst photographic observations of V582 Aur show low-amplitude light variations typical of T Tauri stars. Archival photographic observations indicate that the increase in brightness began in late 1984 or early 1985 and the star reached the maximum level of brightness at 1986 January. The spectral type of V582 Aur can be defined as G0I with strong P Cyg profiles of H alpha and Na I D lines, which are typical of FU Orionis objects. Our BVRI photometric observations show large amplitude variations V~2.8 mag. during ...

  1. Photometric Variability of the Gravitational Lens 0142-100 (UM 673)

    CERN Document Server

    Sinachopoulos, D; Boumis, P; Van Dessel, E L; Bürger, M; Rodríguez-Gil, P; Nakos, Th.

    2001-01-01

    We present the results of a photometric CCD monitoring of the gravitational lens system UM 673, that took place from 1995 to 2000. In total, the doubly-imaged quasar was observed in the R-band during 29 photometric nights, using optical telescopes with dimensions in the range 0.6 m to 1.3 m. We detected a significant variability in the total light of the UM 673 system, that is, in the light of the two QSO images plus the lensing galaxy. With respect to the magnitude of the gravitational lens system at its discovery, in 1986, UM 673 was 0.3 magnitude brighter. Furthermore, our December 1996 measurements show that between November 1995 and October 1997 the system became even brighter, reaching a magnitude difference of 0.5 magnitude with respect to its discovery value. We also present R magnitudes and V-R colours of seven field stars situated in the vicinity of the lens, based on a 3.5-month monitoring during the year 2000.

  2. Proper motion and Photometric Variability of the Candidate Propotoplanet TMR-1C

    CERN Document Server

    Riaz, B

    2010-01-01

    Aims: In their HST/NICMOS observations, Terebey et al. 1998 (T98) detected a candidate protoplanet, TMR-1C, that lies at a separation of about 10" (~1000 AU) from the Class I protostar TMR-1 (IRAS 04361+2547). A narrow filament-like structure was observed extending south-east from the central proto-binary system towards TMR-1C, suggesting a morphology in which the candidate protoplanet may have been ejected from the TMR-1 system. Follow-up low-resolution spectroscopy by Terebey et al. 2000 however could not confirm if this object is a protoplanet or a low-luminosity background star. Methods: We present two epochs of near-infrared photometric observations obtained at the CFHT of the TMR-1 system. The time span of ~7 years between the two sets of observations provides an opportunity to study the proper motion of the components, as well as to check for any photometric variability that would indicate the youth of this source. Results: Our study shows TMR-1C to be co-moving with the protobinary TMR-1AB, based on a...

  3. A Photometric Variability Survey of Field K and M Dwarf Stars with HATNet

    CERN Document Server

    Hartman, J D; Noyes, R W; Sipöcz, B; Kovács, G; Mazeh, T; Shporer, A; Pál, A

    2009-01-01

    Using light curves from the HATNet survey for transiting extrasolar planets we investigate the optical broad-band photometric variability of a sample of 27,560 field K and M dwarfs selected by color and proper-motion. A total of 3496 stars exhibit potential variability, including 95 stars with eclipses and 60 stars with flares. Based on a visual inspection of these light curves and an automated blending classification, we select 1928 stars, including 79 eclipsing binaries, as secure variable star detections that are not high probability blends. We find that only 43 of these stars, including 7 of the eclipsing binaries, have previously been identified as variables or are blended with previously identified variables. One of the newly identified eclipsing binaries is 1RXS J154727.5+450803, a known P = 3.55 day, late M-dwarf SB2 system, for which we derive preliminary estimates for the component masses and radii of M_1 = M_2 = 0.258 +- 0.008 M_Sun and R_1 = R_2 = 0.289 +- 0.007 R_Sun. The radii of the component s...

  4. Var C: Long-term photometric and spectral variability of an LBV in M33

    CERN Document Server

    Burggraf, B; Bomans, D J; Henze, M; Meusinger, H; Sholukhova, O; Zharova, A; Pellerin, A; Becker, A

    2015-01-01

    So far the highly unstable phase of luminous blue variables (LBVs) has not been understood well. It is still uncertain why and which massive stars enter this phase. Investigating the variabilities by looking for a possible regular or even (semi-)periodic behaviour could give a hint at the underlying mechanism for these variations and might answer the question of where these variabilities originate. Finding out more about the LBV phase also means understanding massive stars better in general, which have (e.g. by enriching the ISM with heavy elements, providing ionising radiation and kinetic energy) a strong and significant influence on the ISM, hence also on their host galaxy. Photometric and spectroscopic data were taken for the LBV Var C in M33 to investigate its recent status. In addition, scanned historic plates, archival data, and data from the literature were gathered to trace Var C's behaviour in the past. Its long-term variability and periodicity was investigated. Our investigation of the variability i...

  5. Pruning The ELM Survey: Characterizing Candidate Low-mass White Dwarfs through Photometric Variability

    Science.gov (United States)

    Bell, Keaton J.; Gianninas, A.; Hermes, J. J.; Winget, D. E.; Kilic, Mukremin; Montgomery, M. H.; Castanheira, B. G.; Vanderbosch, Z.; Winget, K. I.; Brown, Warren R.

    2017-02-01

    We assess the photometric variability of nine stars with spectroscopic Teff and log g values from the ELM Survey that locates them near the empirical extremely low-mass (ELM) white dwarf instability strip. We discover three new pulsating stars: SDSS J135512.34+195645.4, SDSS J173521.69+213440.6, and SDSS J213907.42+222708.9. However, these are among the few ELM Survey objects that do not show radial velocity (RV) variations that confirm the binary nature expected of helium-core white dwarfs. The dominant 4.31 hr pulsation in SDSS J135512.34+195645.4 far exceeds the theoretical cut-off for surface reflection in a white dwarf, and this target is likely a high-amplitude δ Scuti pulsator with an overestimated surface gravity. We estimate the probability to be less than 0.0008 that the lack of measured RV variations in four of eight other pulsating candidate ELM white dwarfs could be due to low orbital inclination. Two other targets exhibit variability as photometric binaries. Partial coverage of the 19.342 hr orbit of WD J030818.19+514011.5 reveals deep eclipses that imply a primary radius >0.4 R⊙—too large to be consistent with an ELM white dwarf. The only object for which our time series photometry adds support to ELM white dwarf classification is SDSS J105435.78‑212155.9, which has consistent signatures of Doppler beaming and ellipsoidal variations. We conclude that the ELM Survey contains multiple false positives from another stellar population at Teff ≲ 9000 K, possibly related to the sdA stars recently reported from SDSS spectra.

  6. New Photometrically Variable Magnetic Chemically Peculiar Stars in the ASAS-3 Archive

    CERN Document Server

    Hümmerich, Stefan; Bernhard, Klaus

    2016-01-01

    The magnetic Ap or CP2 stars are natural atomic and magnetic laboratories and ideal testing grounds for the evaluation of model atmospheres. CP2 stars exhibiting photometric variability are traditionally referred to as alpha2 Canum Venaticorum (ACV) variables. Strictly periodic changes are observed in the spectra and brightness of these stars, which allow the derivation of rotational periods. Related to this group of objects are the He-weak (CP4) and He-rich stars, some of which are also known to undergo brightness changes due to rotational modulation. Increasing the sample size of known rotational periods among CP2/4 stars is an important task, which will contribute to our understanding of these objects and their evolution in time. We have compiled an extensive target list of magnetic chemically peculiar (CP2/4) stars. In addition to that, a systematic investigation of early-type (spectral types B/A) variable stars of undetermined type in the International Variable Star Index of the AAVSO (VSX) yielded addit...

  7. Pan-STARRS1 variability of XMM-COSMOS AGN. I. Impact on photometric redshifts

    CERN Document Server

    Simm, T; Salvato, M; Bender, R; Burgett, W S; Chambers, K C; Draper, P W; Flewelling, H; Kaiser, N; Kudritzki, R -P; Magnier, E A; Metcalfe, N; Tonry, J L; Wainscoat, R J; Waters, C

    2015-01-01

    [Abbreviated] Upcoming large area sky surveys like EUCLID and eROSITA crucially depend on accurate photometric redshifts (photo-z). The identification of variable sources, such as AGNs, and the achievable redshift accuracy for varying objects are important in view of the science goals of the EUCLID and eROSITA missions. We probe AGN optical variability for a large sample of X-ray-selected AGNs in the XMM-COSMOS field, using the light curves provided by the Pan-STARRS1 (PS1) 3pi and MDF04 surveys. Utilizing two different variability parameters, we defined a sample of varying AGNs for every PS1 band. We investigated the influence of variability on the calculation of photo-z by applying three different input photometry sets for our fitting procedure. For each of the five PS1 bands, we chose either the epochs minimizing the interval in observing time, the median magnitude values, or randomly drawn light curve points to compute the redshift. In addition, we derived photo-z using PS1 photometry extended by GALEX/IR...

  8. Variable central stars of young planetary nebulae. I. Photometric multisite observations of IC 418.

    Science.gov (United States)

    Handler, G.; Mendez, R. H.; Medupe, R.; Costero, R.; Birch, P. V.; Alvarez, M.; Sullivan, D. J.; Kurtz, D. W.; Herrero, A.; Guerrero, M. A.; Ciardullo, R.; Breger, M.

    1997-04-01

    We report the results of a photometric multisite campaign devoted to HD 35914, the variable central star of the Planetary Nebula IC 418. From the analysis of 120 hours of data acquired with a variety of techniques, we find that HD 35914 exhibits two distinct kinds of variability: irregular light modulation with a time scale of days, as well as cyclic variations with a time scale of 6.5 hours. The short-term variations are not strictly periodic, and cannot be reasonably explained by multiperiodicity; they appear to be semiregular. The star is generally redder when it is brighter; this behavior appears to be connected with the long-term variability. A re-analysis of most of the older data obtained for HD 35914 by various researchers suggests that the basic behavior of the star did not change during the last 15 years. We carefully discuss all the possible causes for the light variations of the star. Rotational modulation of surface features cannot explain the observations, and binarity is unlikely. Pulsations may be excited, but wind variability (or a combination of both) can also not be ruled out.

  9. Physiological, Diurnal and Stress-Related Variability of Cadmium-Metallothionein Gene Expression in Land Snails.

    Science.gov (United States)

    Pedrini-Martha, Veronika; Niederwanger, Michael; Kopp, Renate; Schnegg, Raimund; Dallinger, Reinhard

    2016-01-01

    The terrestrial Roman snail Helix pomatia has successfully adapted to strongly fluctuating conditions in its natural soil habitat. Part of the snail's stress defense strategy is its ability to express Metallothioneins (MTs). These are multifunctional, cysteine-rich proteins that bind and inactivate transition metal ions (Cd(2+), Zn(2+), Cu(+)) with high affinity. In Helix pomatia a Cadmium (Cd)-selective, inducible Metallothionein Isoform (CdMT) is mainly involved in detoxification of this harmful metal. In addition, the snail CdMT has been shown to also respond to certain physiological stressors. The aim of the present study was to investigate the physiological and diurnal variability of CdMT gene expression in snails exposed to Cd and non-metallic stressors such as desiccation and oxygen depletion. CdMT gene expression was upregulated by Cd exposure and desiccation, whereas no significant impact on the expression of CdMT was measured due to oxygen depletion. Overall, Cd was clearly more effective as an inducer of the CdMT gene expression compared to the applied non-metallic stressors. In unexposed snails, diurnal rhythmicity of CdMT gene expression was observed with higher mRNA concentrations at night compared to daytime. This rhythmicity was severely disrupted in Cd-exposed snails which exhibited highest CdMT gene transcription rates in the morning. Apart from diurnal rhythmicity, feeding activity also had a strong impact on CdMT gene expression. Although underlying mechanisms are not completely understood, it is clear that factors increasing MT expression variability have to be considered when using MT mRNA quantification as a biomarker for environmental stressors.

  10. Climatology of diurnal tide and its long-term variability in the lower middle atmosphere over a tropical station

    Science.gov (United States)

    Kumar, P. Vinay; Dutta, Gopa; Mohammad, Salauddin; Rao, B. Venkateswara

    2016-07-01

    ECMWF reanalysis (ERA-interim) data of winds for two solar cycles (1991-2012) are harmonically analyzed to delineate the characteristics and variability of diurnal tide over a tropical site (13.5° N, 79.5° E). The diurnal cycle horizontal winds measured by Gadanki (13.5° N, 79.2° E) mesosphere-stratosphere-troposphere (MST) radar between May 2005 and April 2006 have been used to compute 24 h tidal amplitudes and phases and compared with the corresponding results obtained from ERA winds. The climatological diurnal tidal amplitudes and phases have been estimated from surface to ˜33 km using ERA interim data. The amplitudes and phases obtained in the present study are found to compare reasonably well with Global Scale Wave Model (GSWM-09). Diurnal tides show larger amplitudes in the lower troposphere below 5 km during summer and in the mid-stratosphere mainly during equinoctial months and early winter. Water vapor and convection in the lower troposphere are observed to play major roles in exciting 24-h tide. Correlations between diurnal amplitude and integrated water vapor and between diurnal amplitude and outgoing longwave radiation (OLR) are 0.59 and -0.34, respectively. Ozone mixing ratio correlates (ρ = 0.66) well with diurnal amplitude and shows annual variation in the troposphere whereas semi-annual variation is observed at stratospheric heights with stronger peaks in equinoctial months. A clear annual variation of diurnal amplitude is displayed in the troposphere and interannual variability becomes prominent in the stratosphere which could be partly due to the influence of equatorial stratospheric QBO. The influence of solar activity on diurnal oscillations is found to be insignificant.

  11. A search for photometric variability towards M71 with the Near-Infrared Transiting ExoplanetS Telescope

    Science.gov (United States)

    McCormac, J.; Skillen, I.; Pollacco, D.; Faedi, F.; Ramsay, G.; Dhillon, V. S.; Todd, I.; Gonzalez, A.

    2014-03-01

    We present the results of a high-cadence photometric survey of an 11 arcmin × 11 arcmin field centred on the globular cluster M71, with the Near-Infrared Transiting ExoplanetS Telescope. The aim of our survey is to search for stellar variability and giant transiting exoplanets. This survey differs from previous photometric surveys of M71 in that it is more sensitive to lower amplitude (ΔM ≤ 0.02 mag) and longer period (P > 2 d) variability than previous work on this cluster. We have discovered 17 new variable stars towards M71 and confirm the nature of 13 previously known objects, for which the orbital periods of 7 are refined or newly determined. Given the photometric precision of our high-cadence survey on the horizontal branch of M71, we confirm that the cluster is devoid of RR Lyrae variable stars within the area surveyed. We present new B- and V-band photometry of the stars in our sample from which we estimate spectral types of the variable objects. We also search our survey data for transiting hot Jupiters and present simulations of the expected number of detections. Approximately 1000 stars were observed on the main sequence of M71 with sufficient photometric accuracy to detect a transiting hot Jupiter; however, none were found.

  12. Observing Seasonal and Diurnal Hydrometeorological Variability Within a Tropical Alpine Valley: Implications for Evapotranspiration

    Science.gov (United States)

    Hellstrom, R. A.; Mark, B. G.

    2007-12-01

    Conditions of glacier recession in the seasonally dry tropical Peruvian Andes motivate research to better constrain the hydrological balance in alpine valleys. There is an outstanding need to better understand the impact of the pronounced tropical hygric seasonality on energy and water budgets within pro-glacial valleys that channel glacier runoff to stream flow. This paper presents a novel embedded network installed in the glacierized Llanganuco valley of the Cordillera Blanca (9°S) comprising eight low-cost, discrete temperature and humidity microloggers ranging from 3470 to 4740 masl and an automatic weather station at 3850 masl. Data are aggregated into distinct dry and wet periods sampled from two full annual cycles (2004-2006) to explore patterns of diurnal and seasonal variability. The magnitude of diurnal solar radiation varies little within the valley between the dry and wet periods, while wet season near-surface air temperatures are cooler. Seasonally characteristic diurnal fluctuations in lapse rate partially regulate convection and humidity. Steep lapse rates during the wet season afternoon promote up-slope convection of warm, moist air and nocturnal rainfall events. Standardized grass reference evapotranspiration (ET0) was estimated using the FAO-56 algorithm of the United Nations Food and Agriculture Organization and compared with estimates of actual ET from the process-based BROOK90 model that incorporates more realistic vegetation parameters. Comparisons of composite diurnal cycles of ET for the wet and dry periods suggest about twice the daily ET0 during the dry period, attributed primarily to the 500% higher vapor pressure deficit and 20% higher daily total solar irradiance. Conversely, the near absence of rainfall during the dry season diminishes actual ET below that of the wet season by two orders of magnitude. Nearly cloud-free daylight conditions are critical for ET during the wet season. We found significant variability of ET with elevation

  13. A search for photometric variability in magnetic chemically peculiar stars using ASAS-3 data

    CERN Document Server

    Bernhard, K; Otero, S; Paunzen, E

    2015-01-01

    The (magnetic) chemically peculiar (CP) stars of the upper main sequence are well-suited laboratories for investigating the influence of magnetic fields on the stellar surface because they produce abundance inhomogeneities (spots), which results in photometric variability that is explained in terms of the oblique rotator model. CP stars exhibiting this phenomenon are normally classified as alpha2 Canum Venaticorum (ACV) variables. It is important to increase the sample of known rotational periods among CP stars by discovering new ACV variables. The ASAS-3 data were cross-correlated with the Catalogue of Ap, HgMn, and Am stars in order to analyse the light curves of bona fide CP and related stars. The light curves were downloaded and cleaned of outliers and data points with a flag indicating bad quality. Promising candidates showing a larger scatter than observed for constant stars in the corresponding magnitude range were searched for periodic signals using a standard Fourier technique. In total, we found 323...

  14. Identification of RR Lyrae Variables in SDSS from Single-Epoch Photometric and Spectroscopic Observations

    CERN Document Server

    Wilhelm, Ronald; Beers, Timothy C; Sesar, Branimir; Prieto, Carlos Alende; Carrell, Kenneth W; Lee, Young Sun; Yanny, Brian; Rockosi, Constance M; De Lee, Nathan; Armstrong, Gwen Hansford; Torrence, Stephen J

    2007-01-01

    We describe a new RR Lyrae identification technique based on out-of-phase single-epoch photometric and spectroscopic observations contained in SDSS Data Release 6 (DR-6). This technique detects variability by exploiting the large disparity between the g-r color and the strength of the hydrogen Balmer lines when the two observations are made at random phases. Comparison with a large sample of known variables in the SDSS equatorial stripe (Stripe 82) shows that the discovery efficiency for our technique is ~85%. Analysis of stars with multiple spectroscopic observations suggests a similar efficiency throughout the entire DR-6 sample. We also develop a technique to estimate the average g apparent magnitude (over the pulsation cycle) for individual RR Lyrae stars, using the for the entire sample and measured colors for each star. The resulting distances are found to have precisions of ~14%. Finally, we explore the properties of our DR-6 sample of N = 1087 variables, and recover portions of the Sagittarius Northe...

  15. Searching the short-period variable stars with the photometric algorithm implemented in LUIZA framework

    Science.gov (United States)

    Obara, Lukasz; Żarnecki, Aleksander Filip

    2015-09-01

    Pi of the Sky is a system of wide field-of-view robotic telescopes, which search for short timescale astrophysical phenomena, especially for prompt optical GRB emission. The system was designed for autonomous operation, monitoring a large fraction of the sky with 12m-13m range and time resolution of the order of 1 - 100 seconds. LUIZA is a dedicated framework developed for efficient off-line processing of the Pi of the Sky data, implemented in C++. The photometric algorithm based on ASAS photometry was implemented in LUIZA and compared with the algorithm based on the pixel cluster reconstruction and simple aperture photometry algorithm. Optimized photometry algorithms were then applied to the sample of test images, which were modified to include different patterns of variability of the stars (training sample). Different statistical estimators are considered for developing the general variable star identification algorithm. The algorithm will then be used to search for short-period variable stars in the real data.

  16. New Photometrically Variable Magnetic Chemically Peculiar Stars in the ASAS-3 Archive

    Science.gov (United States)

    Hümmerich, Stefan; Paunzen, Ernst; Bernhard, Klaus

    2016-10-01

    The magnetic Ap or CP2 stars are natural atomic and magnetic laboratories. Strictly periodic changes are observed in the spectra and brightness of these stars, which allow the derivation of rotational periods. Related to this group of objects are the He-weak (CP4) and He-rich stars, some of which also undergo brightness changes due to rotational modulation. Increasing the sample size of known rotational periods among CP2/4 stars is important and will contribute to our understanding of these objects and their evolution in time. We have compiled an extensive target list of CP2/4 stars from the General Catalog of Ap, HgMn, and Am stars, including several early-type (spectral types B/A) variables of undetermined type from the International Variable Star Index. We investigated our sample stars using publicly available observations from the ASAS-3 archive. Our previous efforts in this respect led to the discovery of 323 variable stars. Using a refined analysis approach, we were able to identify another 360 stars exhibiting photometric variability in ASAS-3 data. Summary data, folded light curves and, if available, information from the literature are presented for our final sample, which is composed of 334 bona-fide {α }2 Canum Venaticorum (ACV) variables, 23 ACV candidates, and 3 eclipsing binary systems. Interesting and unusual objects are discussed in detail. In particular, we call attention to HD 66051 (V414 Pup), which is an eclipsing binary system showing obvious rotational modulation of the light curve due to the presence of an ACV variable in the system.

  17. Seasonal and diurnal variability of N2O emissions from a full-scale municipal wastewater treatment plant.

    Science.gov (United States)

    Daelman, Matthijs R J; van Voorthuizen, Ellen M; van Dongen, Udo G J M; Volcke, Eveline I P; van Loosdrecht, Mark C M

    2015-12-01

    During nitrogen removal in conventional activated sludge processes, nitrous oxide can be emitted. With a global warming potential of 298 CO2-equivalents it is an important greenhouse gas that affects the sustainability of wastewater treatment. The present study reports nitrous oxide emission data from a 16 month monitoring campaign on a full-scale municipal wastewater treatment. The emission demonstrated a pronounced diurnal and seasonal variability. This variability was compared with the variability of a number of process variables that are commonly available on a municipal wastewater treatment plant. On a seasonal timescale, the occurrence of peaks in the nitrite concentration correlated strongly with the emission. The diurnal trend of the emission coincided with the diurnal trend of the nitrite and nitrate concentrations in the tank, suggesting that suboptimal oxygen concentrations may induce the production of nitrous oxide during both nitrification and denitrification. This study documents an unprecedented dataset that could serve as a reference for further research.

  18. Seasonal and diurnal variability of N{sub 2}O emissions from a full-scale municipal wastewater treatment plant

    Energy Technology Data Exchange (ETDEWEB)

    Daelman, Matthijs R.J., E-mail: m.r.j.daelman@tudelft.nl [Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft (Netherlands); Department of Biosystems engineering, Ghent University, Coupure links 653, 9000 Gent (Belgium); Voorthuizen, Ellen M. van [Royal HaskoningDHV, P.O. Box 151, 6500AD Nijmegen (Netherlands); Dongen, Udo G.J.M. van [Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft (Netherlands); Volcke, Eveline I.P. [Department of Biosystems engineering, Ghent University, Coupure links 653, 9000 Gent (Belgium); Loosdrecht, Mark C.M. van [Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft (Netherlands)

    2015-12-01

    During nitrogen removal in conventional activated sludge processes, nitrous oxide can be emitted. With a global warming potential of 298 CO{sub 2}-equivalents it is an important greenhouse gas that affects the sustainability of wastewater treatment. The present study reports nitrous oxide emission data from a 16 month monitoring campaign on a full-scale municipal wastewater treatment. The emission demonstrated a pronounced diurnal and seasonal variability. This variability was compared with the variability of a number of process variables that are commonly available on a municipal wastewater treatment plant. On a seasonal timescale, the occurrence of peaks in the nitrite concentration correlated strongly with the emission. The diurnal trend of the emission coincided with the diurnal trend of the nitrite and nitrate concentrations in the tank, suggesting that suboptimal oxygen concentrations may induce the production of nitrous oxide during both nitrification and denitrification. This study documents an unprecedented dataset that could serve as a reference for further research. - Highlights: • Unique dataset of long-term nitrous oxide emission from activated sludge tanks • Emission exhibited pronounced diurnal variability, superimposed on seasonal trend • Seasonal nitrous oxide emission trend correlated with daily nitrite peaks • Emission’s diurnal trend suggests suboptimal oxygen concentrations as cause.

  19. The effect of the number of consecutive night shifts on diurnal rhythms in cortisol, melatonin and heart rate variability (HRV)

    DEFF Research Database (Denmark)

    Jensen, Marie Aarrebo; Garde, Anne Helene; Kristiansen, Jesper

    2016-01-01

    PURPOSE: The purpose of this review is to summarize the current knowledge from field studies on how many consecutive night shifts are required for adaptation of diurnal rhythms in cortisol, melatonin and heart rate variability (HRV) to night work. METHODS: A systematic search of the databases Pub......Med and Web of Science resulted in 18 studies selected for review. RESULTS: Cortisol was measured in five studies, melatonin in 11 studies and HRV in four studies. Diurnal rhythms were assessed by use of several different measures based on three to eight samples per day for cortisol and melatonin and 24-h...... to night work had not occurred after two consecutive night shifts, whereas a small number found evidence for full adaptation after seven consecutive night shifts based on diurnal rhythms in cortisol and melatonin. CONCLUSION: There are methodological differences in the field studies analyzing diurnal...

  20. Diurnal and vertical variability of the sensible heat and carbon dioxide budgets in the atmospheric surface layer

    NARCIS (Netherlands)

    Casso-Torralba, P.; Vilà-Guerau de Arellano, J.; Bosveld, F.; Soler, M.R.; Vermeulen, A.; Werner, C.; Moors, E.J.

    2008-01-01

    The diurnal and vertical variability of heat and carbon dioxide (CO2) in the atmospheric surface layer are studied by analyzing measurements from a 213 m tower in Cabauw (Netherlands). Observations of thermodynamic variables and CO2 mixing ratio as well as vertical profiles of the turbulent fluxes

  1. Study of Diurnal Cycle Variability of Planetary Boundary Layer Characteristics over the Red Sea and Arabian Peninsula

    KAUST Repository

    Li, Weigang

    2012-07-01

    This work is aimed at investigating diurnal cycle variability of the planetary boundary layer characteristics over the Arabian Peninsula and the Red Sea region. To fulfill this goal the downscaling simulations are performed using Weather Research and Forecasting (WRF) model. We analyze planetary boundary layer height, latent and sensible heat fluxes, and surface air temperature. The model results are compared with observations in different areas, for different seasons, and for different model resolutions. The model results are analyzed in order to better quantify the diurnal cycle variability over the Arabian Peninsula and the Red Sea. The specific features of this region are investigated and discussed.

  2. Diurnal variation in heart rate variability before and after maximal exercise testing.

    Science.gov (United States)

    Armstrong, Rachel G; Kenny, Glen P; Green, Geoffrey; Seely, Andrew J E

    2011-05-01

    As heart-rate variability (HRV) is under evaluation in clinical applications, the authors sought to better define the interdependent impact of age, maximal exercise, and diurnal variation under physiologic conditions. The authors evaluated the diurnal changes in HRV 24-h pre- and post-maximal aerobic exercise testing to exhaustion in young (19-25 yrs, n = 12) and middle-aged (40-55 yrs, n = 12) adults. Subjects wore a portable 5-lead electrocardiogram holter for 48 h (24 h prior to and following a maximal aerobic capacity test). Time-, frequency-, time-frequency-, and scale-invariant-domain measures of HRV were computed from RR-interval data analyzed using a 5-min window size and a 2.5-min step size, resulting in a different set of outputs every 2.5 min. Results were averaged (mean ± SE) over four prespecified time periods during the morning, afternoon, evening, and night on Day 1 and Day 2. Diurnal changes in HRV in young and middle-aged adults were compared using a two-way, repeated-measures analysis of variance (ANOVA). Young adults demonstrated higher HRV compared to middle-aged adults during periods of wakefulness and sleep prior to maximal exercise stress testing (i.e., high-frequency power during Day 1: young adults: morning 1862 ± 496 ms(2), afternoon 1797 ± 384 ms(2), evening 1908 ± 431 ms(2), and night 3202 ± 728 ms(2); middle-aged adults: morning 341 ± 53 ms(2), afternoon 405 ± 68 ms(2), evening 469 ± 80 ms(2), and night 836 ± 136 ms(2)) (p Exercise resulted in reductions in HRV such that multiple measures of HRV were not significantly different between age groups during the afternoon and evening periods. All measures of HRV demonstrated between-group differences overnight on Day 2 (p change in HRV from sleep to morning with exercise is greater in younger subjects. These physiologic results have clinical significance in understanding the pathophysiology of altered variability in

  3. Mapping Clouds and Terrain of Earth-like Planets from Photometric Variability

    CERN Document Server

    Kawahara, Hajime

    2011-01-01

    We develop an inversion technique of annual scattered light curves to sketch a two-dimensional albedo map of exoplanets. As a test-bed for future observations of extrasolar terrestrial planets, we apply this mapping technique to simulated light curves of a mock Earth-twin. A primary feature in recovered albedo maps traces the annual mean distribution of clouds. To extract information of other surface types, we attempt to reduce the cloud signal by taking difference of two bands. We find that the inversion of reflectivity difference between 0.8-0.9 and 0.4-0.5 micron bands roughly recover the continental distribution, except for high latitude regions persistently covered with clouds and snow. The inversion of the reflectivity difference across the red edge (0.8-0.9 and 0.6-0.7 micron) emphasizes the vegetation features near the equator. The planetary obliquity and equinox can be estimated simultaneously with the mapping under the presence of clouds. We conclude that the photometric variability of the scattered...

  4. A 16-yr photometric campaign on the eclipsing novalike variable DW Ursae Majoris

    Science.gov (United States)

    Boyd, D. R. S.; de Miguel, E.; Patterson, J.; Wood, M. A.; Barrett, D.; Boardman, J.; Brettman, O.; Cejudo, D.; Collins, D.; Cook, L. M.; Cook, M. J.; Foote, J. L.; Fried, R.; Gomez, T. L.; Hambsch, F.-J.; Jones, J. L.; Kemp, J.; Koff, R.; Koppelman, M.; Krajci, T.; Lemay, D.; Martin, B.; McClusky, J. V.; Menzies, K.; Messier, D.; Roberts, G.; Robertson, J.; Rock, J.; Sabo, R.; Skillman, D.; Ulowetz, J.; Vanmunster, T.

    2017-04-01

    We present an analysis of photometric observations of the eclipsing novalike variable DW UMa made by the CBA consortium between 1999 and 2015. Analysis of 372 new and 260 previously published eclipse timings reveals a 13.6 yr period or quasi-period in the times of minimum light. The seasonal light curves show a complex spectrum of periodic signals: both positive and negative 'superhumps', likely arising from a prograde apsidal precession and a retrograde nodal precession of the accretion disc. These signals appear most prominently and famously as sidebands of the orbital frequency; but the precession frequencies themselves, at 0.40 and 0.22 cycles per day, are also seen directly in the power spectrum. The superhumps are sometimes seen together, and sometimes separately. The depth, width and skew of eclipses are all modulated in phase with both nodal and apsidal precession of the tilted and eccentric accretion disc. The superhumps, or more correctly the precessional motions that produce them, may be essential to understanding the mysterious 'SW Sextantis' syndrome. Disc wobble and eccentricity can both produce Doppler signatures inconsistent with the true dynamical motions in the binary, and disc wobble might boost the mass-transfer rate by enabling the hot white dwarf to directly irradiate the secondary star.

  5. Photometric Variability in Kepler Target Stars: The Sun Among Stars -- A First Look

    CERN Document Server

    Basri, Gibor; Batalha, Natalie; Gilliland, Ronald L; Jenkins, Jon; Borucki, William J; Koch, David; Caldwell, Doug; Dupree, Andrea K; Latham, David W; Meibom, Soeren; Howell, Steve; Brown, Tim

    2010-01-01

    The Kepler mission provides an exciting opportunity to study the lightcurves of stars with unprecedented precision and continuity of coverage. This is the first look at a large sample of stars with photometric data of a quality that has heretofore been only available for our Sun. It provides the first opportunity to compare the irradiance variations of our Sun to a large cohort of stars ranging from vary similar to rather different stellar properties, at a wide variety of ages. Although Kepler data is in an early phase of maturity, and we only analyze the first month of coverage, it is sufficient to garner the first meaningful measurements of our Sun's variability in the context of a large cohort of main sequence stars in the solar neighborhood. We find that nearly half of the full sample is more active than the active Sun, although most of them are not more than twice as active. The active fraction is closer to a third for the stars most similar to the Sun, and rises to well more than half for stars cooler t...

  6. Photometric Variability of the Disk Integrated Infrared Emission of the Earth

    CERN Document Server

    Gómez-Leal, I; Selsis, F

    2012-01-01

    We present an analysis of the global-integrated mid-infrared emission flux of the Earth based on data derived from satellite measurements. We have studied the photometric annual, seasonal, and rotational variability of the thermal emission of the Earth to determine which properties can be inferred from the point-like signal. We find that the analysis of the time series allows us to determine the 24 hr rotational period of the planet for most observing geometries, due to large warm and cold areas, identified with geographic features, which appear consecutively in the observer's planetary view. However, the effects of global-scale meteorology can effectively mask the rotation for several days at a time. We also find that orbital time series exhibit a seasonal modulation, whose amplitude depends strongly on the latitude of the observer but weakly on its ecliptic longitude. As no systematic difference of brightness temperature is found between the dayside and nightside, the phase variations of the Earth in the in...

  7. Diurnal variability of water vapour in the Baltic Sea region according to NCEP-CFSR and BaltAn65+ reanalyses

    Directory of Open Access Journals (Sweden)

    Erko Jakobson

    2014-03-01

    Full Text Available Diurnal variations in water vapour in the Baltic Sea region are examined using BaltAn65+ and NCEP-CFSR reanalyses of summer (JJA data for the period 1979-2005. A systematic difference between precipitable water (PW diurnal variability above the land and the water is revealed. Above the land, PW diurnal variability has minimal values at 00 and 06 UTC, as in previous studies, whereas above the water, the minima are at 12 and 18 UTC. Diurnal variability in the vertical humidity profile is controlled by turbulent mixing and the diurnal behaviour of sea breezes. The impacts and proportions of diurnal variability of humidity are evaluated at different vertical levels.

  8. A Search for Photometric Variability Towards M71 with the Near-Infrared Transiting ExoplanetS Telescope

    CERN Document Server

    McCormac, J; Pollacco, D; Faedi, F; Ramsay, G; Dhillon, V S; Todd, I; Gonzalez, A

    2013-01-01

    We present the results of a high-cadence photometric survey of an $11'\\times11'$ field centred on the globular cluster M71, with the Near-Infrared Transiting ExoplanetS Telescope. The aim of our survey is to search for stellar variability and transiting giant exoplanets. This survey differs from previous photometric surveys of M71 in that it is more sensitive to lower amplitude ($\\Delta M\\leq0.02$ mag) and longer period ($P>2$ d) variability than previous work on this cluster. We have discovered $17$ new variable stars towards M71 and confirm the nature of $13$ previously known objects, for which the orbital periods of $7$ are refined or newly determined. Given the photometric precision of our high-cadence survey on the horizontal branch of M71, we confirm the cluster is devoid of RR Lyrae variable stars within the area surveyed. We present new $B$ and $V$ band photometry of the stars in our sample from which we estimate spectral types of the variable objects. We also search our survey data for transiting hot...

  9. The Solar Neighborhood XXXVI: The Long-Term Photometric Variability of Nearby Red Dwarfs in the VRI Optical Bands

    CERN Document Server

    Hosey, Altonio D; Jao, Wei-Chun; Dieterich, Sergio B; Winters, Jennifer G; Lurie, John C; Riedel, Adric R; Subasavage, John P

    2015-01-01

    We present an analysis of long-term photometric variability for nearby red dwarfs at optical wavelengths. The sample consists of 264 M dwarfs south of DEC = +30 with V-K = 3.96-9.16 and Mv~10-20 (spectral types M2V-M8V), most of which are within 25 pc. The stars have been observed in the VRI filters for ~4-14 years at the CTIO/SMARTS 0.9m telescope. Of the 238 red dwarfs within 25 pc, we find that only ~8% are photometrically variable by at least 20 mmag (~2%) in the VRI bands. We find that high variability at optical wavelengths over the long-term can be used to identify young stars. Overall, however, the fluxes of most red dwarfs at optical wavelengths are steady to a few percent over the long term. The low overall rate of photometric variability for red dwarfs is consistent with results found in previous work on similar stars on shorter timescales, with the body of work indicating that most red dwarfs are only mildly variable. We highlight 17 stars that show long-term changes in brightness, sometimes becau...

  10. Physical and optical properties of aerosols over an urban location in Spain: seasonal and diurnal variability

    Directory of Open Access Journals (Sweden)

    H. Lyamani

    2010-01-01

    Full Text Available Measurements of aerosol optical properties and aerosol number size distribution obtained during the period from December 2005 to November 2007 at Granada, an urban site in south-eastern Spain, are analyzed. Large variations of the measured variables have been found, and related to variations in emissions sources and meteorological conditions. High values of aerosol absorption and scattering coefficients are obtained during winter and low values are measured during summer. This seasonal pattern in the surface aerosol optical properties is opposite to the seasonal cycle showed by columnar aerosol optical depth. The differences in the seasonal features of the surface and column-integrated data are related to seasonal variations in the aerosol vertical distribution, aerosol sources and boundary layer height. In winter the number density of "fine" particles (0.5s, presents an evident seasonal cycle with values of 1.8±0.2, 1.6±0.3, 1.3±0.3 and 1.4±0.3 in winter, spring, summer and autumn, respectively. This suggests the presence of a large fraction of submicron particles at the site, especially during winter. The aerosols measured in this study contain a large fraction of absorbing material as indicated by the average single-scattering albedo that has values of 0.65±0.07, 0.66±0.06, 0.70±0.06 and 0.73±0.06 in autumn, winter, spring and summer, respectively. The aerosol scattering albedo obtained in the surface boundary layer of Granada is below the critical value of 0.86 that determines the shift from cooling to warming. These results put in evidence the need of efforts to reduce absorbing particles (black carbon emissions to avoid the possible warming that would result from the

  11. Physical and optical properties of aerosols over an urban location in Spain: seasonal and diurnal variability

    Directory of Open Access Journals (Sweden)

    H. Lyamani

    2009-09-01

    Full Text Available Measurements of aerosol optical properties and aerosol number size distribution obtained during the period from December 2005 to November 2007 at Granada, an urban site in south-eastern Spain, are analyzed. Large variations of the measured variables have been found, and related to variations in emissions sources and meteorological conditions. High values of aerosol absorption and scattering coefficients are obtained during winter and low values are measured during summer. This seasonal pattern in the surface aerosol optical properties is opposite to the seasonal cycle showed by columnar aerosol optical depth. The differences in the seasonal features of the surface and column-integrated data are related to seasonal variations in the aerosol vertical distribution, aerosol sources and boundary layer height. In winter the number density of fine particles (0.5s, presents an evident seasonal cycle with values of 1.8±0.2, 1.6±0.3, 1.3±0.3 and 1.4±0.3 in winter, spring, summer and autumn, respectively. This suggests the presence of a large fraction of submicron particles at the site, especially during winter. Urban aerosols in Granada contain a large fraction of absorbing material as indicated by the average single-scattering albedo that has values of 0.65±0.07, 0.66±0.06, 0.70±0.06 and 0.73±0.06 in autumn, winter, spring and summer, respectively. The aerosol scattering albedo obtained in the surface boundary layer of Granada is below the critical value of 0.86 that determines the shift from cooling to warming. These results put in evidence the need of efforts to reduce absorbing particles (black carbon emissions to avoid the possible warming that would result from the reductions of

  12. Diurnal and seasonal variability in radial distribution of sap flux density: Implications for estimating stand transpiration.

    Science.gov (United States)

    Fiora, Alessandro; Cescatti, Alessandro

    2006-09-01

    Daily and seasonal patterns in radial distribution of sap flux density were monitored in six trees differing in social position in a mixed coniferous stand dominated by silver fir (Abies alba Miller) and Norway spruce (Picea abies (L.) Karst) in the Alps of northeastern Italy. Radial distribution of sap flux was measured with arrays of 1-cm-long Granier probes. The radial profiles were either Gaussian or decreased monotonically toward the tree center, and seemed to be related to social position and crown distribution of the trees. The ratio between sap flux estimated with the most external sensor and the mean flux, weighted with the corresponding annulus areas, was used as a correction factor (CF) to express diurnal and seasonal radial variation in sap flow. During sunny days, the diurnal radial profile of sap flux changed with time and accumulated photosynthetic active radiation (PAR), with an increasing contribution of sap flux in the inner sapwood during the day. Seasonally, the contribution of sap flux in the inner xylem increased with daily cumulative PAR and the variation of CF was proportional to the tree diameter, ranging from 29% for suppressed trees up to 300% for dominant trees. Two models were developed, relating CF with PAR and tree diameter at breast height (DBH), to correct daily and seasonal estimates of whole-tree and stand sap flow obtained by assuming uniform sap flux density over the sapwood. If the variability in the radial profile of sap flux density was not accounted for, total stand transpiration would be overestimated by 32% during sunny days and 40% for the entire season.

  13. Amazon forest structure generates diurnal and seasonal variability in light utilization

    Directory of Open Access Journals (Sweden)

    D. C. Morton

    2015-12-01

    Full Text Available The complex three-dimensional (3-D structure of tropical forests generates a diversity of light environments for canopy and understory trees. Understanding diurnal and seasonal changes in light availability is critical for interpreting measurements of net ecosystem exchange and improving ecosystem models. Here, we used the Discrete Anisotropic Radiative Transfer (DART model to simulate leaf absorption of photosynthetically active radiation (lAPAR for an Amazon forest. The 3-D model scene was developed from airborne lidar data, and local measurements of leaf reflectance, aerosols, and PAR were used to model lAPAR under direct and diffuse illumination conditions. Simulated lAPAR under clear sky and cloudy conditions was corrected for light saturation effects to estimate light utilization, the fraction of lAPAR available for photosynthesis. Although the fraction of incoming PAR absorbed by leaves was consistent throughout the year (0.80–0.82, light utilization varied seasonally (0.67–0.74, with minimum values during the Amazon dry season. Shadowing and light saturation effects moderated potential gains in forest productivity from increasing PAR during dry season months when the diffuse fraction from clouds and aerosols was low. Comparisons between DART and other models highlighted the role of 3-D forest structure to account for seasonal changes in light utilization. Our findings highlight how directional illumination and forest 3-D structure combine to influence diurnal and seasonal variability in light utilization, independent of further changes in leaf area, leaf age, or environmental controls on canopy photosynthesis. Changing illumination geometry constitutes an alternative biophysical explanation for observed seasonality in Amazon forest productivity without changes in canopy phenology.

  14. Amazon forest structure generates diurnal and seasonal variability in light utilization

    Science.gov (United States)

    Morton, Douglas C.; Rubio, Jérémy; Cook, Bruce D.; Gastellu-Etchegorry, Jean-Philippe; Longo, Marcos; Choi, Hyeungu; Hunter, Maria; Keller, Michael

    2016-04-01

    The complex three-dimensional (3-D) structure of tropical forests generates a diversity of light environments for canopy and understory trees. Understanding diurnal and seasonal changes in light availability is critical for interpreting measurements of net ecosystem exchange and improving ecosystem models. Here, we used the Discrete Anisotropic Radiative Transfer (DART) model to simulate leaf absorption of photosynthetically active radiation (lAPAR) for an Amazon forest. The 3-D model scene was developed from airborne lidar data, and local measurements of leaf reflectance, aerosols, and PAR were used to model lAPAR under direct and diffuse illumination conditions. Simulated lAPAR under clear-sky and cloudy conditions was corrected for light saturation effects to estimate light utilization, the fraction of lAPAR available for photosynthesis. Although the fraction of incoming PAR absorbed by leaves was consistent throughout the year (0.80-0.82), light utilization varied seasonally (0.67-0.74), with minimum values during the Amazon dry season. Shadowing and light saturation effects moderated potential gains in forest productivity from increasing PAR during dry-season months when the diffuse fraction from clouds and aerosols was low. Comparisons between DART and other models highlighted the role of 3-D forest structure to account for seasonal changes in light utilization. Our findings highlight how directional illumination and forest 3-D structure combine to influence diurnal and seasonal variability in light utilization, independent of further changes in leaf area, leaf age, or environmental controls on canopy photosynthesis. Changing illumination geometry constitutes an alternative biophysical explanation for observed seasonality in Amazon forest productivity without changes in canopy phenology.

  15. Contemporary model fidelity over the Maritime Continent: Examination of the diurnal cycle, synoptic, intraseasonal and seasonal variability

    Science.gov (United States)

    Baranowski, Dariusz

    2017-04-01

    One of the key challenges in subseasonal weather forecasting is the fidelity in representing the propagation of the Madden-Julian Oscillation (MJO) across the Maritime Continent (MC). In reality both propagating and non-propagating MJO events are observed, but in numerical forecast the latter group largely dominates. The fact that models still struggle to realistically represent the MJO over MC is generally attributed to its complex terrain and associated vigorous diurnal cycle of convection, multi-scale interactions between local and propagating modes of convection and regional air-sea interactions. In this study, multi-model simulations from the GEWEX Atmospheric System Study (GASS) / Year of Tropical Convection (YOTC) MJO Project are analyzed to quantify contemporary model performance in representing the MC mean climate and its variability, including the diurnal cycle, synoptic, intraseasonal, and seasonal variability. This dataset has been shown to be useful in such multi-model evaluation studies over different regions and/or focusing on different physical processes (e.g. Jiang et al., JGR, 2015; Mani et al., Clim. Dyn, 2016) For this study, comprehensive model performances are evaluated using metrics that utilize the mean precipitation pattern and the amplitude and phase of the diurnal cycle, with a particular focus on the linkage between a model's local MC variability and its fidelity in representing propagation of the MJO and equatorial Kelvin waves across the MC. Subseasonal to seasonal variability of mean precipitation and its diurnal cycle in 20 year long climate simulations from over 20 general circulation models (GCMs) is examined to benchmark model performance. Furthermore, we utilize cross model differences to gain insight into which processes are most critical to realistically represent multi-scale interactions over the MC region. This includes distinguishing the behavior between a number of land (Sumatra, Borneo, New Guinea and Southeast Asia) and

  16. ESA STSE Project “Sea Surface Temperature Diurnal Variability: Regional Extend – Implications in Atmospheric Modelling”

    DEFF Research Database (Denmark)

    Karagali, Ioanna

    , atmospheric and oceanic modelling, bio-chemical processes and oceanic CO2 studies. The diurnal variability of SST, driven by the coincident occurrence of low enough wind and solar heating, is currently not properly understood. Atmospheric, oceanic and climate models are currently not adequately resolving...... present the final project findings regarding the analysis of hourly SEVIRI SSTs from SEVIRI over the Atlantic Ocean and the European Seas, revealing the regional extend of diurnal warming. As satellite SSTs are representative of the upper centimetre of the water column, they do not provide information...

  17. On the diurnal variability in F2-region plasma density above the EISCAT Svalbard radar

    Directory of Open Access Journals (Sweden)

    J. Moen

    2008-08-01

    Full Text Available Two long runs of EISCAT Svalbard Radar (ESR, in February 2001 and October 2002, have been analysed with respect to variability in the F2 region peak density and altitude. The diurnal variation in the F2 peak density exhibits one maximum around 12:00 MLT and another around 23:00 MLT, consistent with solar wind controlled transport of EUV ionized plasma across the polar cap from day to night. High density plasma patch material is drawn in through the cusp inflow region independent of IMF BY. There is no apparent IMF BY asymmetry on the intake of high density plasma, but the trajectory of its motion is strongly BY dependent. Comparison with the international reference ionosphere model (IRI2001 clearly demonstrates that the model does not take account of the cross-polar transport of F2-region plasma, and hence has limited applicability in polar cap regions.

  18. Monthly and Diurnal Variability of Rain Rate and Rain Attenuation during the Monsoon Period in Malaysia

    Directory of Open Access Journals (Sweden)

    U.Kesavan

    2014-06-01

    Full Text Available Rain is the major source of attenuation for microwave propagation above 10 GHz. In tropical and equatorial regions where the rain intensity is higher, designing a terrestrial and earth-to-satellite microwave links is very critical and challenging at these frequencies. This paper presents the preliminary results of rain effects in a 23 GHz terrestrial point-to-point communication link 1.3km long. The experimental test bed had been set up at Skudai, Johor Bahru, Malaysia. In this area, a monsoon equatorial climate prevails and the rainfall rate can reach values well above 100mm/h with significant monthly and diurnal variability. Hence, it is necessary to implement a mitigation technique for maintaining an adequate radio link performance for the action of very heavy rain. Since we now know that the ULPC (Up Link Power Control cannot guarantee the desired performance, a solution based on frequency band diversity is proposed in this paper. Here, a secondary radio link operating in a frequency not affected by rain (C band for instance is placed parallel with the main link. Under no rain or light rain conditions, the secondary link carries without priority radio signals. When there is an outage of the main link due to rain, the secondary link assumes the priority traffic. The outcome of the research shows a solution for higher operating frequencies during rainy events.

  19. The Tokar Gap Jet: Regional Circulation, Diurnal Variability, and Moisture Transport Based on Numerical Simulations

    KAUST Repository

    Davis, Shannon R.

    2015-05-14

    The structure, variability, and regional connectivity of the Tokar Gap jet (TGJ) are described using WRF Model analyses and supporting atmospheric datasets from the East African–Red Sea–Arabian Peninsula (EARSAP) region during summer 2008. Sources of the TGJ’s unique quasi-diurnal nature and association with atypically high atmospheric moisture transport are traced back to larger-scale atmospheric dynamics influencing its forcing. These include seasonal shifts in the intertropical convergence zone (ITCZ), variability of the monsoon and North African wind regimes, and ties to other orographic flow patterns. Strong modulation of the TGJ by regional processes such as the desert heating cycle, wind convergence at the ITCZ surface front, and the local land–sea breeze cycle are described. Two case studies present the interplay of these influences in detail. The first of these was an “extreme” gap wind event on 12 July, in which horizontal velocities in the Tokar Gap exceeded 26 m s−1 and the flow from the jet extended the full width of the Red Sea basin. This event coincided with development of a large mesoscale convective complex (MCC) and precipitation at the entrance of the Tokar Gap as well as smaller gaps downstream along the Arabian Peninsula. More typical behavior of the TGJ during the 2008 summer is discussed using a second case study on 19 July. Downwind impact of the TGJ is evaluated using Lagrangian model trajectories and analysis of the lateral moisture fluxes (LMFs) during jet events. These results suggest means by which TGJ contributes to large LMFs and has potential bearing upon Sahelian rainfall and MCC development.

  20. The global surface composition of 67P/Churyumov-Gerasimenko nucleus by Rosetta/VIRTIS. II) Diurnal and seasonal variability

    Science.gov (United States)

    Ciarniello, M.; Raponi, A.; Capaccioni, F.; Filacchione, G.; Tosi, F.; De Sanctis, M. C.; Kappel, D.; Rousseau, B.; Arnold, G.; Capria, M. T.; Barucci, M. A.; Quirico, E.; Longobardo, A.; Kuehrt, E.; Mottola, S.; Erard, S.; Bockelée-Morvan, D.; Leyrat, C.; Migliorini, A.; Zinzi, A.; Palomba, E.; Schmitt, B.; Piccioni, G.; Cerroni, P.; Ip, W.-H.; Rinaldi, G.; Salatti, M.

    2016-11-01

    VIRTIS-M observations of the nucleus of comet 67P/Churyumov-Gerasimenko acquired from 2014 August to 2015 May have been analysed to investigate surface temporal variability at both seasonal and diurnal scales. The measured reflectance spectra are studied by means of comet spectral indicators (CSI) such as slopes in the visible and infrared ranges, and 3.2 μm band area and band centre. CSI maps derived from data acquired at different heliocentric distances (from 3.62 to 1.72 au) along the inbound leg of the comet's orbit are used to infer surface water ice abundance. We measure a global scale enrichment of water ice from 2014 August to 2015 May across the body of the comet, along with variability at small spatial scale, possibly related with the local insolation conditions. Analysis of water ice diurnal variability is performed on 2014 August observations. Water ice appears at the border of receding shadows in the neck of the comet (Hapi), sublimating in less than 1 h, after exposure to sunlight. As similar variability is not observed in other regions of the comet, we interpreted this as the expression of a diurnal cycle of sublimation and re-condensation of water ice, triggered by sudden shadowing produced on the neck by the body and the head of the nucleus.

  1. Diurnal spatial variability of soil respiration estimated by ordinary kriging and sequential Gaussian simulation

    Science.gov (United States)

    de Bortoli Teixeira, Daniel; Rodrigo Panosso, Alan; Tadeu Pereira, Gener; Pelegrino Cerri, Carlos Eduardo; La Scala, Newton, Jr.

    2010-05-01

    The role of greenhouse gases in the climate change is well know, however, the balance of greenhouse gases due to land use and management is still lacking. Hence it is important to characterize the main aspects of soil respiration (or soil CO2 emission) in agricultural areas, including its spatial variability, as quantitatively as possible. The objective of this work was to study the diurnal spatial variability of the soil respiration including their estimations by different methods: ordinary kriging and sequential Gaussian simulation. Evaluations were conducted in a regular grid having 64 points installed over a bare Eutrustox clay texture during the morning and afternoon periods. Measurements were conducted from 7:30 - 10:30 am (morning) and 13:30 - 16:30 pm (afternoon) using a portable soil respiration system (LI-8100), Lincoln, NE, USA. In order to estimate the best interpolation method it was applied the so-called external validation, where the respiration values of 5 points in grid were removed from interpolation process and after were estimated in the same points by kriging or sequential Gaussian simulation methods. This evaluation was also based on the sum of the square of residues, comparing observed with predicted respiration values in each of the 5 points selected for external validation. The highest CO2 emission was observed in the afternoon period, with mean value of 6.24 µmol m-2 s-1, when compared to the morning (4.54 µmol m-2 s-1). Our results indicate that the measurement period (morning or afternoon) did not interfere into the definition of emission spatial variability structure, as coefficient of variation, spatial variability models and their parameters were quite similar in morning and afternoon. However, despite the high correlation between kriging and sequential Gaussian simulation respiration maps (R2 =0.99) sequential Gaussian simulation showed to be more efficient into the estimations of non-sampled emissions in both periods, mornings and

  2. Photometrics Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — Purpose:The Photometrics Laboratory provides the capability to measure, analyze and characterize radiometric and photometric properties of light sources and filters,...

  3. School burnout: increased sympathetic vasomotor tone and attenuated ambulatory diurnal blood pressure variability in young adult women.

    Science.gov (United States)

    May, Ross W; Sanchez-Gonzalez, Marcos A; Fincham, Frank D

    2015-01-01

    Two studies examined autonomic and cardiovascular functioning that may link school burnout to cardiovascular risk factors in young healthy adult females. Study 1 (N = 136) investigated whether school burnout was related to resting values of blood pressure (BP) and blood pressure variability (BPV) through laboratory beat-to-beat BP assessment. Study 2 (N = 94) examined the link between school burnout and diurnal BPV through ambulatory BP monitoring. Controlling for anxiety and depressive symptomatology, school burnout demonstrated strong positive relationships with indices of cardiac sympathovagal tone, sympathetic vasomotor tone, inefficient myocardial oxygen consumption, increased 24-h ambulatory heart rate and BP, blunted BP diurnal variability, and increased arterial stiffness. These studies establish cardiovascular biomarkers of school burnout and suggest that even in a seemingly healthy sample school burnout may predispose females to increased cardiovascular risk. Several future lines of research are outlined.

  4. A numerical study on nonlinear propagation and short-term variability of the migrating diurnal and semidiurnal tides

    Institute of Scientific and Technical Information of China (English)

    HUANG Chunming; ZHANG Shaodong; YI Fan

    2005-01-01

    By using a three-dimensional fully nonlinear numerical model in spherical coordinates and taking the linear steady solutions of the migrating diurnal and semidiurnal tides in January from the Global-Scale Wave Model (GSWM) as the initial values, we simulate the linear and nonlinear propagations of the migrating diurnal and semidiurnal tides in the atmosphere from the ground to the lower thermosphere. A comparison of our simulations with the results of GSWM is also presented. The simulation results show that affected by the nonlinearity, the migrating diurnal and semidiurnal tides propagating in the middle and upper atmosphere exhibit evident short-term variability. The nonlinear interactions between the migrating tides and the background atmosphere can obviously alter the background wind and temperature fields, which suggests that the nonlinear propagations of the migrating diurnal and semidiurnal tides impact significantly on the transient dynamical and thermal structures of the background middle and upper atmosphere and the nonlinear effect is an important cause of the difference between the results of GSWM and observations.

  5. Satellite-based Dust Source Identification over North Africa: Diurnal Cycle, Meteorological Controls, and Interannual Variability

    Science.gov (United States)

    Schepanski, Kerstin; Tegen, Ina; Macke, Andreas

    2010-05-01

    Mineral dust aerosol emitted from arid and semi-arid areas impacts on the weather and climate system by affecting e.g. radiation fluxes and nutrient cycles. To estimate the effect of dust aerosol, detailed knowledge on the spatio-temporal distribution of active dust sources is necessary. For a better representation of dust-related processes in numerical models and climate change projections the knowledge on the natural variability of dust source activity has to be improved. As dust sources are mostly located over remote areas satellite observations are suitable for identifying active dust sources. The accuracy of dust source identification using such an indirect method is limited by the temporal resolution and the ambiguities of the retrieval. Here, a data set on the spatial (1°x1°) and temporal (3-hourly) distribution of dust source activations (DSA) over North Africa is compiled by analyzing 15-minute Meteosat Second Generation (MSG) infra-red (IR) dust index images since March 2006. The index is designed using radiances measured by the Spinning Enhanced Visible and Infra-Red Imager (SEVIRI) on-board MSG at 8.7 µm, 10.8 µm and 12.0 µm which are converted to brightness temperatures (BTs). To strengthen the dust signal, differences of BTs are used to compute RGB-composite images. This newly data set providing information on the diurnal cycle of dust emission has been used (1) to identify most active dust source areas, and (2) to investigate on the temporal distribution of DSAs. Over the Sahara Desert 65% of dust sources become active during 06-09 UTC pointing towards an important role of the break-down of the nocturnal low-level jet (LLJ) for dust mobilization besides other meteorological features like density currents, haboobs, and cyclones. Furthermore the role of the nocturnal LLJs for dust mobilization over the Sahara is investigated by weather observations and a regional modeling study. Four years of DSA observations indicate an interannual variability in

  6. Meteorological controls on the diurnal variability of carbon monoxide mixing ratio at a mountaintop monitoring site in the Appalachian Mountains

    Directory of Open Access Journals (Sweden)

    Temple R. Lee

    2015-05-01

    Full Text Available The variability of trace gases such as carbon monoxide (CO at surface monitoring stations is affected by meteorological forcings that are particularly complicated over mountainous terrain. A detailed understanding of the impact of meteorological forcings on trace gas variability is challenging, but is vital to distinguish trace gas measurements affected by local pollutant sources from measurements representative of background mixing ratios. In the present study, we investigate the meteorological and CO characteristics at Pinnacles (38.61 N, 78.35 W, 1017 m above mean sea level, a mountaintop monitoring site in northwestern Virginia, USA, in the Appalachian Mountains, from 2009 to 2012, and focus on understanding the dominant meteorological forcings affecting the CO variability on diurnal timescales. The annual mean diurnal CO cycle shows a minimum in the morning between 0700 and 0900 LST and a maximum in the late afternoon between 1600 and 2000 LST, with a mean (median daily CO amplitude of 39.2±23.7 ppb (33.2 ppb. CO amplitudes show large day-to-day variability. The largest CO amplitudes, in which CO mixing ratios can change >100 ppb in <3 h, occur in the presence of synoptic disturbances. Under fair weather conditions, local- to regional-scale transport processes are found to be more important drivers of the diurnal CO variability. On fair weather days with northwesterly winds, boundary layer dilution causes a daytime CO decrease, resembling the variability observed atop tall towers in flat terrain. Fair weather days with a wind shift from the northwest to the south are characterised by an afternoon CO increase and resemble the variability observed at mountaintops influenced by the vertical transport of polluted air from adjacent valleys.

  7. Seasonal variability of diurnal temperature range in Egypt with links to atmospheric circulations and sea surface temperature

    Science.gov (United States)

    El Kenawy, A.; Lopez Moreno, J. I.; Vicente-Serrano, S.

    2010-09-01

    The diurnal temperature range (DTR) is an important climate-change variable. Seasonal and annual variability of DTR in Egypt was investigated based on a monthly dataset of 40 observatories distributing across the country. The trends were calculated using the Rho spearman rank test at the 95 % level of significance. The trends at the independent individual scale were compared with a regional series created for the whole country following the Thiessen polygon approach. A cross-tabulation analysis was performed between the trends of the DTR and the trends of maximum and minimum temperatures to account for directional causes of variability of the DTR at seasonal and annual scales. The physical processes controlling the DTR variability were also assessed in terms of large atmospheric circulations representing in the indices of the North Atlantic Oscillation (NAO), the East Atlantic (EA) pattern, El Niño Southern Oscillation (ENSO) index and the EAWR (East Atlantic/West Russia) Pattern. Also, the variability of the DTR was linked with anomaly of Sea Surface Temperature (SST). A cooling trend was observed in Egypt with strong behavior in winter and summer rather than fall and spring. The upwarding trend of the mean minimum temperature was mainly responsible for variability of the DTR rather than the mean maximum temperature. Also, the EA and the EAWR indices were the main indices accounted for most of variation in the DTR in Egypt, particularly in summer. Key words: trend analysis, temperature variability, Diurnal temperature range, atmospheric circulation, sea surface temperature, Egypt.

  8. Quantitative and qualitative assessment of diurnal variability in tropospheric humidity using SAPHIR on-board Megha-Tropiques

    Science.gov (United States)

    Uma, K. N.; Das, Siddarth Shankar

    2016-08-01

    The global diurnal variability of relative humidity (RH) from August 2012 to May 2014 is discussed for the first time using 'Sounder for Atmospheric Profiling of Humidity in the Inter-tropical Regions (SAPHIR)', a microwave humidity sounder onboard Megha-Tropiques (MT). It is superior to other microwave satellite humidity sounders in terms of its higher repetitive cycle in the tropics owing to its low-inclination orbit and the availability of six dedicated humidity sounding channels. The six layers obtained are 1000-850, 850-700, 700-550, 550-400, 400-250 and 250-100 hPa. Three hourly data over a month has been combined using equivalent day analysis to attain a composite profile of complete diurnal cycle in each grid (2.5°×2.5°). A distinct diurnal variation is obtained over the continental and the oceanic regions at all the layers. The magnitude in the lower tropospheric humidity (LTH), middle tropospheric humidity (MTH) and the upper tropospheric humidity (UTH) show a large variability over the continental regions compared to that over oceans. The monthly variability of the diurnal variation over the years has also been discussed by segregating into five different continental and four different oceanic regions. Afternoon peaks dominate in the LTH over the land and the desert regions. The MTH is found to vary between the evening and the early morning hours over different geographical regions and not as consistent as that of the LTH. The UTH maximum magnitude is generally observed during the early morning hours, over the continents. Interestingly, the Oceanic regions are found to have a dominant magnitude in the afternoon hours similar to that of the continents in the LTH, evening maximum in the MTH and the early morning maximum in the UTH. The underlying mechanisms involved in the variability of humidity over different regions are also discussed. The study reveals the complexity involved in the understanding the diurnal variability over the continents and open

  9. Change in diurnal variations of meteorological variables induced by anthropogenic aerosols over the North China Plain

    Science.gov (United States)

    Zhang, Meigen; Gao, Yi; Liu, Xiaohong; Wang, Lili

    2016-04-01

    This study investigates the impacts of all anthropogenic aerosols and anthropogenic black carbon (BC) on the diurnal variations of meteorological variables in the atmospheric boundary layer over the North China Plain (NCP) during June to August 2008, using a coupled meteorology and chemistry model (WRF-Chem). The results of the ensemble numerical experiments show that surface air temperature decreases by about 0.6 to 1.2 K with the maximum decrease over the Beijing urban area and the southern part of Hebei province, and the surface relative humidity (RH) increases by 2-4 % owing to all anthropogenic aerosols. On the contrary, anthropogenic BC induces a small change of temperature and RH at surface. Averaged for Beijing, Tianjin, and Hebei province (BTH region) and High Particle Concentration (HPC) periods when PM2.5 surface concentration is more than 60 μg m-3 and daily AOD is more than 0.9, all anthropogenic aerosols decrease air temperature under 850 hPa and increase it between 500 and 850 hPa, while anthropogenic BC increases it for whole atmosphere. The maximum changes occur at 08:00-20:00 (local time). Aerosol-induced surface energy and diabatic heating change leads to a cooling at the surface and in the lower atmosphere and a warming in the middle troposphere at 08:00-17:00, with reversed effects at 20:00-05:00. BC cools the atmosphere at the surface and warms the atmosphere above for the whole day. As a result, the equivalent potential temperature profile change shows that the lower atmosphere is more stable at 08:00 and 14:00. All anthropogenic aerosols decrease the surface wind speed by 20-60 %, while anthropogenic BC decreases the wind speed by 10-40 % over the NCP with the maximum decrease at 08:00. The aerosol-induced stabilization of the lower atmosphere favors the accumulation of air pollutants and thus contributes to deterioration of visibility and fog-haze events.

  10. The effects of the diurnal atmospheric variability on entry, descent and landing on Mars

    Directory of Open Access Journals (Sweden)

    Marčeta D.

    2014-01-01

    Full Text Available Landing on Mars is extremely challenging task due to the fact that the Martian atmosphere is the most hostile environment in the Solar system to perform the entry, descent and landing (EDL process, because it is thick enough to create substantial heating of the entry vehicle but not thick enough to reduce its velocity to the one necessary for safe landing. Beside this, the atmosphere is very dynamic mainly due to high eccentricity of the Martian orbit, obliquity of the orbital to the equatorial plane and close alignment of the winter solstice and the orbital perihelion. Although seasonal variations of atmospheric parameters are significantly larger than the diurnal, it is very important to analyze diurnal cycles as they can significantly change vertical and horizontal atmospheric profiles in very short time intervals. This can present a serious threat to missions which have very precise timings and specific requirements such as the requirement for the daytime landing to enable ground images acquisition during the descent and landing phase. A 3-degrees-of-freedom trajectory integration routine was combined with the Mars Global Reference Atmospheric Model (Mars-GRAM to identify the dependence of the EDL profiles on the diurnal cycles of atmospheric parameters throughout the Martian year. The obtained results show that the influence of the diurnal cycles is the largest at the equator and decreases relatively symmetrically towards the poles with a slightly stronger influence in the northern hemisphere. Also, there is a significant influence of the orbital position of Mars on the effect of diurnal atmospheric variations which causes that, around the orbital perihelion and winter solstice, there is some kind of inversion of the dependance of optimal entry timing on latitude of the landing site comparing to the rest of the Martian year. [Projekat Ministarstva nauke Republike Srbije, br. 176002

  11. Sensitivity of Initial Conditions on Diurnal Variability of Indian Summer Monsoon

    Science.gov (United States)

    Das, Sukanta Kumar; Deb, Sanjib Kumar; Kishtawal, C. M.; Pal, Pradip Kumar

    2015-10-01

    The diurnal cycle of different surface parameters, viz. surface air temperature, surface pressure, and rain intensities, simulated by the Community Atmosphere Model (CAM) in the operational seasonal forecast of ISM-2012 using initial conditions (ICs) taken at synoptic hours of the day has been examined and compared with observations. Four members were simulated with ICs at 0000, 0600, 1200, and 1800 UTC on 1 August 2012. The impact of the initial conditions at the synoptic hours of the day was more visible over the landmass compared with the oceanic regions. The diurnal variation of the surface temperature in the model simulation showed the major features when compared with the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis except for the warm pool of northwest India and the Tibetan region. The surface pressure in the ECMWF reanalysis showed the semidiurnal cycle with two peaks at 0600 UTC and 1800 UTC; however, the range of the cycle was underestimated by the model simulation, showing only one peak at 0600 UTC. Significant variations in the diurnal cycle of rain intensities were seen among the different members. The model captured the diurnal cycle as the positive and negative peaks at 1200 and 0000 UTC with intensities at the peaks ~0.5 mm high and low, respectively, in the model simulation when compared with the observations. Presently, the seasonal forecast of ISM is generated through ensemble CAM experiments using different ICs taken from different dates but all at 0000 UTC. Consideration of ICs at different times of the day will add different ranges of diurnal variations in all the surface parameters within the family of ensemble members and also increase the number of members in the family. Indeed, these improve the ensemble processes in generating the seasonal forecast of ISM.

  12. Variability of radiatively forced diurnal cycle of intense convection in the tropical west pacific

    Energy Technology Data Exchange (ETDEWEB)

    Gray, W.M.; Sheaffer, J.D.; Thorson, W.B. [Colorado State Univ., Fort Collins, CO (United States)

    1996-04-01

    Strong differences occur in daytime versus nighttime (DVN) net radiative cooling in clear versus cloudy areas of the tropical atmosphere. Daytime average cooling is approximately -0.7{degrees}C/day, whereas nighttime net tropospheric cooling rates are about -1.5{degrees}C/day, an approximately two-to-one difference. The comparatively strong nocturnal cooling in clear areas gives rise to a diurnally varying vertical circulation and horizontal convergence cycle. Various manifestations of this cyclic process include the observed early morning heavy rainfall maxima over the tropical oceans. The radiatively driven DVN circulation appears to strongly modulate the resulting diurnal cycle of intense convection which creates the highest, coldest cloudiness over maritime tropical areas and is likely a fundamental mechanism governing both small and large scale dynamics over much of the tropical environment.

  13. Seasonal and diurnal variability in historical warming due to the urbanization of Hokkaido, Japan

    Science.gov (United States)

    Sugimoto, Shiori; Sato, Tomonori; Sasaki, Tomonori

    2015-06-01

    The influence of historical urbanization on warming trends observed on Hokkaido Island (Japan) is discussed with an emphasis on seasonally and diurnally differential responses of air temperature to urban effects. Two numerical experiments using past and current land use scenarios successfully simulated the observed temperature trends, showing a greater rate of warming in winter than in summer and a greater increase in daily minimum than daily maximum temperatures. The results suggest that seasonal and diurnal variations in the thermal structure of the planetary boundary layer play a leading role in determining the warming rate of surface air. Under strongly stable stratification, anomalous heating within the urban canopy dissipates into a near-surface shallow layer, resulting in increased daily minimum temperatures during winter. In summer, however, anomalous urban heating due to increased Bowen ratios is attenuated by vertical mixing in the convective daytime boundary layer, suppressing the impact of urban heating on surface warming.

  14. Hydroxyl in the stratosphere and mesosphere – Part 1: Diurnal variability

    Directory of Open Access Journals (Sweden)

    K. Minschwaner

    2011-02-01

    Full Text Available Diurnal variations in hydroxyl (OH in the stratosphere and mesosphere are analyzed using measurements from the Aura Microwave Limb Sounder (MLS. The primary driver for OH diurnal variations is the ultraviolet actinic flux that initiates the photochemical production of reactive hydrogen species. The magnitude of this flux is governed largely by changes in solar zenith angle (SZA throughout the day, and OH diurnal variations are well approximated by an exponential function of the secant of SZA. Measured OH concentrations are fit to a function of the form exp[−βsec(SZA], where the parameter β is a function of altitude. We examine the magnitude of β and show that it is related to the optical depths of ultraviolet absorption by ozone and molecular oxygen. Values of β from SLIMCAT model simulations show the same vertical structure as those from MLS and the average level of agreement between model and measurements is 6%. The vertical profile of β from MLS can be represented by a simple analytic formulation involving the ozone and water vapor photodissociation rates. This formulation is used to infer the altitude dependence of the primary production mechanisms for OH: the reaction of excited-state atomic oxygen with water vapor versus the direct photodissociation of water vapor.

  15. California's wind energy resource: seasonal, synoptic, and diurnal characteristics, and variability on several time scales

    Science.gov (United States)

    Mansbach, D. K.; Cayan, D. R.

    2009-12-01

    Decades worth of observational data are used to analyze the annual cycle, relevant synoptic climatology, and diurnal patterns of wind in California's major wind generation regions. Wind records near the wind farms at San Gorgonio and Tehachapi passes, Southern California, and Solano County, Northern California near Sacramento are employed. The in situ data are complemented by global reanalysis, 10-km dynamically downscaled regional reanalysis, and other weather station and buoy data. Each site shows preferred wind directions dictated by local orographic forcing as well as different peaks in wind speed and direction distribution in each season, which are explained in terms of climatological circulation patterns. All have greater wind energy in the warmer months, although the northern site peaks later in the summer, more in phase with the temperature cycle but lagging the cycle in zonal SLP gradient that the other sites align with. The dominant patterns associated with high winds, classified with self-organizing maps, feature a North Pacific SLP high and western North American low. The interplay between synoptic forcing and local circulations is also explored. Local circulations are especially important in the warm months when mesoscale SLP gradients are set up by diurnal heating. The northernmost site displays sharp diurnal wind increases as remnants of a sea breeze propagate inland to the site and amplify the wind induced by the cross-valley SLP gradient.

  16. Hydroxyl in the stratosphere and mesosphere – Part 1: Diurnal variability

    Directory of Open Access Journals (Sweden)

    K. Minschwaner

    2010-09-01

    Full Text Available Diurnal variations in hydroxyl (OH in the stratosphere and mesosphere are analyzed using measurements from the Aura Microwave Limb Sounder (MLS. The primary driver for OH diurnal variations is the ultraviolet actinic flux that initiates photochemical reactions which produce OH. The magnitude of this flux is governed largely by changes in solar zenith angle (SZA throughout the day, and OH diurnal variations are well approximated by an exponential function of the secant of SZA. Measured OH concentrations are fit to a function of the form exp[−βsec(SZA], where the parameter β is a function of altitude. We examine the magnitude of β and show that it is related to the optical depths of ultraviolet absorption by ozone and oxygen. Comparison of β values obtained from SLIMCAT model simulations with those derived from MLS observations shows very good agreement. The vertical profile of β from MLS can be represented by a simple analytic formulation involving the ozone and water vapor photodissociation rates. This formulation is used to infer the altitude dependence of the primary production mechanisms for OH: the reaction of excited-state atomic oxygen with water vapor versus the direct photodissociation of water vapor.

  17. The OmegaWhite survey for Short-Period Variable Stars III: Follow-up Photometric and Spectroscopic Observations

    CERN Document Server

    Macfarlane, S A; Groot, P J; Ramsay, G; Toma, R; Motsoaledi, M; Crause, L A; Gilbank, D G; O'Donoghue, D; Potter, S B; Sickafoose, A A; van Gend, C; Worters, H L

    2016-01-01

    We present photometric and spectroscopic follow-up observations of short-period variables discovered in the OmegaWhite survey: a wide-field high-cadence g-band synoptic survey targeting the Galactic Plane. We have used fast photometry on the SAAO 1.0-m and 1.9-m telescopes to obtain light curves of 27 variables, and use these results to validate the period and amplitude estimates from the OmegaWhite processing pipeline. Furthermore, 57 sources (44 unique, 13 also with new light curves) were selected for spectroscopic follow-up using either the SAAO 1.9-m telescope or the Southern African Large Telescope. We find many of these variables have spectra which are consistent with being delta Scuti type pulsating stars. At higher amplitudes, we detect four possible pulsating white dwarf/subdwarf sources and an eclipsing cataclysmic variable. Due to their rarity, these targets are ideal candidates for detailed follow-up studies. From spectroscopy, we confirm the symbiotic binary star nature of two variables identifie...

  18. The OmegaWhite survey for short-period variable stars - III: follow-up photometric and spectroscopic observations

    Science.gov (United States)

    Macfarlane, S. A.; Woudt, P. A.; Groot, P. J.; Ramsay, G.; Toma, R.; Motsoaledi, M.; Crause, L. A.; Gilbank, D. G.; O'Donoghue, D.; Potter, S. B.; Sickafoose, A. A.; van Gend, C.; Worters, H. L.

    2017-02-01

    We present photometric and spectroscopic follow-up observations of short-period variables discovered in the OmegaWhite survey, a wide-field high-cadence g-band synoptic survey targeting the Galactic Plane. We have used fast photometry on the SAAO 1.0- and 1.9-m telescopes to obtain light curves of 27 variables, and use these results to validate the period and amplitude estimates from the OmegaWhite processing pipeline. Furthermore, 57 sources (44 unique, 13 with new light curves) were selected for spectroscopic follow-up using either the SAAO 1.9-m telescope or the Southern African Large Telescope. We find that many of these variables have spectra which are consistent with being δ Scuti-type pulsating stars. At higher amplitudes, we detect four possible pulsating white dwarf/subdwarf sources and an eclipsing cataclysmic variable. Due to their rarity, these targets are ideal candidates for detailed follow-up studies. From spectroscopy, we confirm the symbiotic binary star nature of two variables identified as such in the SIMBAD database. We also report what could possibly be the first detection of the `Bump Cepheid' phenomena in a δ Scuti star, with OW J175848.21-271653.7 showing a pronounced 22 per cent amplitude dip lasting 3 min during each pulsational cycle peak. However, the precise nature of this target is still uncertain as it exhibits the spectral features of a B-type star.

  19. ESA STSE Project “Sea Surface Temperature Diurnal Variability: Regional Extend – Implications in Atmospheric Modelling”

    DEFF Research Database (Denmark)

    Karagali, Ioanna

    Sea Surface Temperature (SST) and ocean-surface winds have been identified as essential variables by the Global Climate Observing system (GCO). Satellite observations have aided the understanding of air-sea interactions and the important role these two parameters hold in climate related studies, ...... located offshore. The project resulted in expanding the scientific background for understanding the spatial and temporal variability of key climate variables and their representativity in atmospheric and oceanic models....... of the vertical extend of diurnal signals. Drifting buoys provide measurements close to the surface but are not always available. Moored buoys are generally not able to resolve the daily SST signal, which strongly weakens with depth within the upper water column. For such reasons, the General Ocean Turbulence...

  20. Mapping Earth-analogs from Photometric Variability: Spin-Orbit Tomography for Planets in Inclined Orbits

    CERN Document Server

    Fujii, Yuka

    2012-01-01

    Aiming at obtaining detailed information of surface environment of Earth-analogs, Kawahara & Fujii 2011 proposed an inversion technique of annual scattered light curves named the spin-orbit tomography (SOT), which enables one to sketch a 2-dimensional albedo map from annual variation of the disk-integrated scattered light, and demonstrated the method with a planet in a face-on orbit. We extend it to be applicable to general geometric configurations, including low-obliquity planets like the Earth in inclined orbits. We simulate light curves of the Earth in an inclined orbit in three photometric bands (0.4-0.5um, 0.6-0.7um, and 0.8-0.9um) and show that the distribution of clouds, snow, and continents are retrieved with the aid of the SOT. We also demonstrate the SOT by applying it to an upright Earth, a tidally-locked Earth, and Earth-analogs with ancient continental configurations. The inversion is model-independent in the sense that we do not assume specific albedo models when mapping the surface, and hen...

  1. Wake flow variability in a wind farm throughout the diurnal cycle

    Science.gov (United States)

    Abkar, Mahdi; Sharifi, Ahmad; Porté-Agel, Fernando

    2015-04-01

    The atmospheric boundary layer (ABL) undergoes substantial changes in its structure and dynamics in the course of a day due to the transient nature of forcing factors such as the surface fluxes of heat and momentum. The non-stationary nature of the mean wind and turbulence in the ABL, associated with the diurnal cycle, can in turn affect the structure of wind turbine wakes and their effects on power losses within wind farms. In this research, large-eddy simulation (LES) is used to study the evolution of the turbine wakes and their effects on power losses inside an idealized finite-size wind farm in the course of two full diurnal cycles. In the LES, turbulent subgrid-scale stresses are modeled using tuning-free Lagrangian scale-dependent dynamic models, while the turbine-induced forces are parameterized using a dynamic actuator disk model with rotation. To minimize the effects of the initial conditions on the results, our analysis is focused on the second diurnal cycle. The simulation results show a strong effect of atmospheric stability on the wind farm wakes and associated power losses. During the night, the relatively low turbulence intensity of the ambient ABL flow results in a relatively slow rate of entrainment of momentum into the wake and, consequently, a slow wake recovery. In contrast, during the day the positive buoyancy flux and associated turbulence production lead to a relatively high turbulence level in the background ABL flow, which enhances turbulent mixing and wake recovery. As a result, the averaged power deficit in the wind farm is found to increase with increasing thermal stability. In particular for that day, the averaged power deficit increased from 28% under the most convective condition to about 66% under the most stable condition.

  2. Improved Variable Star Search in Large Photometric Data Sets -- New Variables in CoRoT Field LRa02 Detected ba BEST II

    CERN Document Server

    Fruth, T; Cabrera, J; Chini, R; Csizmadia, Sz; Eigmüller, P; Erikson, A; Kirste, S; Lemke, R; Murphy, M; Pasternacki, T; Rauer, H; Titz-Weider, R; 10.1088/0004-6256/143/6/140

    2012-01-01

    The CoRoT field LRa02 has been observed with the Berlin Exoplanet Search Telescope II (BEST II) during the southern summer 2007/2008. A first analysis of stellar variability led to the publication of 345 newly discovered variable stars. Now, a deeper analysis of this data set was used to optimize the variability search procedure. Several methods and parameters have been tested in order to improve the selection process compared to the widely used J index for variability ranking. This paper describes an empirical approach to treat systematic trends in photometric data based upon the analysis of variance statistics that can significantly decrease the rate of false detections. Finally, the process of reanalysis and method improvement has virtually doubled the number of variable stars compared to the first analysis by Kabath et al. A supplementary catalog of 272 previously unknown periodic variables plus 52 stars with suspected variability is presented. Improved ephemerides are given for 19 known variables in the ...

  3. Modeling the diurnal variability of agricultural ammonia in Bakersfield, California, during the CalNex campaign

    Science.gov (United States)

    Lonsdale, Chantelle R.; Hegarty, Jennifer D.; Cady-Pereira, Karen E.; Alvarado, Matthew J.; Henze, Daven K.; Turner, Matthew D.; Capps, Shannon L.; Nowak, John B.; Neuman, J. Andy; Middlebrook, Ann M.; Bahreini, Roya; Murphy, Jennifer G.; Markovic, Milos Z.; VandenBoer, Trevor C.; Russell, Lynn M.; Scarino, Amy Jo

    2017-02-01

    NH3 retrievals from the NASA Tropospheric Emission Spectrometer (TES), as well as surface and aircraft observations of NH3(g) and submicron NH4(p), are used to evaluate modeled concentrations of NH3(g) and NH4(p) from the Community Multiscale Air Quality (CMAQ) model in the San Joaquin Valley (SJV) during the California Research at the Nexus of Air Quality and Climate Change (CalNex) campaign. We find that simulations of NH3 driven with the California Air Resources Board (CARB) emission inventory are qualitatively and spatially consistent with TES satellite observations, with a correlation coefficient (r2) of 0.64. However, the surface observations at Bakersfield indicate a diurnal cycle in the model bias, with CMAQ overestimating surface NH3 at night and underestimating it during the day. The surface, satellite, and aircraft observations all suggest that daytime NH3 emissions in the CARB inventory are underestimated by at least a factor of 2, while the nighttime overestimate of NH3(g) is likely due to a combination of overestimated NH3 emissions and underestimated deposition.Running CMAQ v5.0.2 with the bi-directional NH3 scheme reduces NH3 concentrations at night and increases them during the day. This reduces the model bias when compared to the surface and satellite observations, but the increased concentrations aloft significantly increase the bias relative to the aircraft observations. We attempt to further reduce model bias by using the surface observations at Bakersfield to derive an empirical diurnal cycle of NH3 emissions in the SJV, in which nighttime and midday emissions differ by about a factor of 4.5. Running CMAQv5.0.2 with a bi-directional NH3 scheme together with this emissions diurnal profile further reduces model bias relative to the surface observations. Comparison of these simulations with the vertical profile retrieved by TES shows little bias except for the lowest retrieved level, but the model bias relative to flight data aloft increases

  4. The First Detection of Photometric Variability in a Y Dwarf: WISE J140518.39+553421.3

    CERN Document Server

    Cushing, Michael C; Trucks, Jesica L; Morley, Caroline V; Gizis, John E; Marley, Mark S; Fortney, Jonathan J; Kirkpatrick, J Davy; Gelino, Christopher R; Mace, Gregory N; Carey, Sean J

    2016-01-01

    We present the first detection of photometric variability of a spectroscopically-confirmed Y dwarf. The Infrared Array Camera on board the Spitzer Space Telescope was used to obtain times series photometry at 3.6 and 4.5 microns over a twenty four hour period at two different epochs separated by 149 days. Variability is evident at 4.5 um in the first epoch and at 3.6 and 4.5 um in the second epoch which suggests that the underlying cause or causes of this variability change on the timescales of months. The second-epoch [3.6] and [4.5] light curves are nearly sinusoidal in form, in phase, have periods of roughly 8.5 hours, and have semi-amplitudes of 3.5%. We find that a simple geometric spot model with a single bright spot reproduces these observations well. We also compare our measured semi-amplitudes of the second epoch light curves to predictions of the static, one-dimensional, partly cloudy and hot spot models of Morley and collaborators and find that neither set of models can reproduce the observed [3.6]...

  5. Investigating the mechanisms of diurnal rainfall variability over Peninsular Malaysia using the non-hydrostatic regional climate model

    Science.gov (United States)

    Jamaluddin, Ahmad Fairudz; Tangang, Fredolin; Chung, Jing Xiang; Juneng, Liew; Sasaki, Hidetaka; Takayabu, Izuru

    2017-07-01

    This study aims to provide a basis for understanding the mechanisms of diurnal rainfall variability over Peninsular Malaysia by utilising the Non-Hydrostatic Regional Climate Model (NHRCM). The present day climate simulations at 5 km resolution over a period of 20 years, from 1st December 1989 to 31st January 2010 were conducted using the six-hourly Japanese re-analysis 55 years (JRA-55) data and monthly Centennial in situ Observation Based Estimates (COBE) of sea surface temperature as lateral and lower boundary conditions. Despite some biases, the NHRCM performed reasonably well in simulating diurnal rainfall cycles over Peninsular Malaysia. During inter-monsoon periods, the availability of atmospheric moisture played a major role in modulating afternoon rainfall maxima over the foothills of the Titiwangsa mountain range (FT sub-region). During the southwest monsoon, a lack of atmospheric moisture inhibits the occurrence of convective rainfall over the FT sub-region. The NHRCM was also able to simulate the suppression of the diurnal rainfall cycle over the east coast of Peninsular Malaysia (EC sub-region) and afternoon rainfall maximum over the Peninsular Malaysia inland-valley (IN sub-region) area during the northeast monsoon. Over the EC sub-region, daytime radiational warming of the top of clouds enhanced atmospheric stability, thus reducing afternoon rainfall. On the other hand, night-time radiational cooling from cloud tops decreases atmospheric stability and increases nocturnal rainfall. In the early morning, the rainfall maximum was confined to the EC sub-region due to the retardation of the north-easterly monsoonal wind by the land breeze and orographic blocking. However, in the afternoon, superimposition of the sea breeze on the north-easterly monsoonal wind strengthened the north-easterly wind, thus causing the zone of convection to expand further inland.

  6. Photometric variability in the old open cluster M 67. II. General Survey

    CERN Document Server

    Stassun, K G; Mathieu, R D; Verbunt, F

    2001-01-01

    We use differential CCD photometry to search for variability in BVI among 990 stars projected in and around the old open cluster M 67. In a previous paper we reported results for 22 cluster members that are optical counterparts to X-ray sources; this study focuses on the other stars in our observations. A variety of sampling rates were employed, allowing variability on time scales ranging from \\sim 0.3 hours to \\sim 20 days to be studied. Among the brightest sources studied, detection of variability as small as sigma approx 10 mmag is achieved (with > 3 sigma confidence); for the typical star observed, sensitivity to variability at levels sigma approx 20 mmag is achieved. The study is unbiased for stars with 12.5 < B < 18.5, 12.5 < V < 18.5, and 12 < I < 18 within a radius of about 10 arcmin from the cluster centre. In addition, stars with 10 < BVI < 12.5 were monitored in a few small regions in the cluster. We present photometry for all 990 sources studied, and report the variability ...

  7. Seasonal-Latitudinal Variability of the Eastward-Propagating Diurnal Tide with Zonal Wavenumber s =-3 (DE3)

    Science.gov (United States)

    Zhang, Xiaoli; Zhang, Xiaoli; Forbes, Jeffrey M.; Hagan, Maura; Zhang, Yuanchong; Tao, Wei-Kuo

    It is now well-accepted that the eastward-propagating diurnal tide with zonal wavenumber s = -3 (DE3) is of comparable importance to the migrating diurnal tide at equatorial and low latitudes. In particular, through the dynamo electric fields that this tide produces, it is likely responsible for longitudinal wave-4 structures in the F-region ionosphere that have recently been observed. However, to date dynamical models have not been successful in replicating the seasonal-latitudinal wind and temperature structures of DE3 as revealed by UARS and TIMED measurements. In this paper, we utilize the Global-Scale Wave Model (GSWM) combined with new observationally-based heating rates and zonal mean wind structures to better understand the factors responsible for DE3 variability. The new heating rates we employ are from the International Satellite Cloud Climatology Project (ISSCP) for radiative heating and from the Tropical Rainfall Measuring Mission (TRMM) for convective heating. The options we explore for specification of zonal mean zonal winds include monthly climatologies derived from UARS/HRDI winds and SABER temperatures.

  8. Relating jet structure to photometric variability: the Herbig Ae star HD 163296

    NARCIS (Netherlands)

    L.E. Ellerbroek; L. Podio; C. Dougados; S. Cabrit; M.L. Sitko; H. Sana; L. Kaper; A. de Koter; P.D. Klaassen; G.D. Mulders; I. Mendigutía; C.A. Grady; K. Grankin; H. van Winckel; F. Bacciotti; R.W. Russell; D.K. Lynch; H.B. Hammel; L.C. Beerman; A.N. Day; D.M. Huelsman; C. Werren; A. Henden; J. Grindlay

    2014-01-01

    Herbig Ae/Be stars are intermediate-mass pre-main sequence stars surrounded by circumstellar dust disks. Some are observed to produce jets, whose appearance as a sequence of shock fronts (knots) suggests a past episodic outflow variability. This "jet fossil record" can be used to reconstruct the out

  9. A Photometric Study of the Pulsating Variable Star TYC 0075 01143 1

    Science.gov (United States)

    Khruslov, A. V.; Kusakin, A. V.

    2013-09-01

    We present the results of our new observations of TYC 0075 01143 1, a recently discovered double-mode delta Scuti variable. We improved the frequencies f0 and f1 and pulsation amplitudes, detected the interaction frequencies f1+f0, f1-f0, and a possible nonradial frequency fN.

  10. A photometric variability study of massive stars in Cygnus OB2

    CERN Document Server

    Salas, J; Barbá, R H

    2014-01-01

    We have conducted a 1.5 year-long variability study of the stars in the Cygnus OB2 association, the region in the northern hemisphere with the highest density of optically visible massive stars. The survey was conducted using four pointings in the Johnson $R$ and $I$ bands with a 35 cm Meade LX200-ACF telescope equipped with a 3.2 Mpixel SBIG ST10-XME CCD camera and includes 300+ epochs in each filter. A total of 1425 objects were observed with limiting magnitudes of 15 in $R$ and 14 in $I$. The photometry was calibrated using reference stars with existing $UBVJHK$ photometry. Bright stars have precisions better than 0.01 magnitudes, allowing us to detect 52 confirmed and 19 candidate variables, many of them massive stars without previous detections as variables. Variables are classified as eclipsing, pulsating, irregular/long period, and Be. We derive the phased light curves for the eclipsing binaries, with periods ranging from 1.3 to 8.5 days.

  11. A Model for (Quasi-)Periodic Multi-wavelength Photometric Variability in Young Stellar Objects

    CERN Document Server

    Kesseli, Aurora Y; Wood, Kenneth; Whitney, Barbara A; Hillenbrand, L A; Gregory, Scott G; Stauffer, J R; Morales-Calderon, M; Rebull, L; Alencar, S H P

    2016-01-01

    We present radiation transfer models of rotating young stellar objects (YSOs) with hotspots in their atmospheres, inner disk warps and other 3-D effects in the nearby circumstellar environment. Our models are based on the geometry expected from the magneto-accretion theory, where material moving inward in the disk flows along magnetic field lines to the star and creates stellar hotspots upon impact. Due to rotation of the star and magnetosphere, the disk is variably illuminated. We compare our model light curves to data from the Spitzer YSOVAR project (Morales-Calderon et al. 2014, Cody et al. 2014) to determine if these processes can explain the variability observed at optical and mid-infrared wavelengths in young stars. We focus on those variables exhibiting "dipper" behavior that may be periodic, quasi-periodic, or aperiodic. We find that the stellar hotspot size and temperature affects the optical and near-infrared light curves, while the shape and vertical extent of the inner disk warp affects the mid-IR...

  12. Variable stars in the bar of the Large Magellanic Cloud: the photometric catalogue

    CERN Document Server

    Fabrizio, L D; Maio, M; Bragaglia, A; Carretta, E; Gratton, R; Montegriffo, P; Zoccali, M

    2004-01-01

    The catalogue of the Johnson-Cousins B,V and I light curves obtained for 162 variable stars (135 RR Lyrae, 4 candidate Anomalous Cepheids, 11 Classical Cepheids, 11 eclipsing binaries and 1 delta Scuti star) in two areas close to the bar of the Large Magellanic Cloud is presented along with coordinates, finding charts, periods, epochs, amplitudes, and mean quantities (intensity- and magnitude-averaged luminosities) of the variables with full coverage of the light variations. A star by star comparison is made with MACHO and OGLE II photometries based on both variable and constant stars in common, and the transformation relationships to our photometry are provided. The pulsation properties of the RR Lyrae stars in the sample are discussed in detail. Parameters of the Fourier decomposition of the light curves are derived for the fundamental mode RR Lyrae stars with complete and regular curves (29 stars). They are used to estimate metallicities, absolute magnitudes, intrinsic (B-V)o colours, and temperatures of t...

  13. Studying the photometric and spectroscopic variability of the magnetic hot supergiant ζ Orionis Aa

    Science.gov (United States)

    Buysschaert, B.; Neiner, C.; Richardson, N. D.; Ramiaramanantsoa, T.; David-Uraz, A.; Pablo, H.; Oksala, M. E.; Moffat, A. F. J.; Mennickent, R. E.; Legeza, S.; Aerts, C.; Kuschnig, R.; Whittaker, G. N.; Popowicz, A.; Handler, G.; Wade, G. A.; Weiss, W. W.

    2017-06-01

    Massive stars play a significant role in the chemical and dynamical evolution of galaxies. However, much of their variability, particularly during their evolved supergiant stage, is poorly understood. To understand the variability of evolved massive stars in more detail, we present a study of the O9.2Ib supergiant ζ Ori Aa, the only currently confirmed supergiant to host a magnetic field. We have obtained two-color space-based BRIght Target Explorer photometry (BRITE) for ζ Ori Aa during two observing campaigns, as well as simultaneous ground-based, high-resolution optical CHIRON spectroscopy. We perform a detailed frequency analysis to detect and characterize the star's periodic variability. We detect two significant, independent frequencies, their higher harmonics, and combination frequencies: the stellar rotation period Prot = 6.82 ± 0.18 d, most likely related to the presence of the stable magnetic poles, and a variation with a period of 10.0 ± 0.3 d attributed to circumstellar environment, also detected in the Hα and several He I lines, yet absent in the purely photospheric lines. We confirm the variability with Prot/4, likely caused by surface inhomogeneities, being the possible photospheric drivers of the discrete absorption components. No stellar pulsations were detected in the data. The level of circumstellar activity clearlydiffers between the two BRITE observing campaigns. We demonstrate that ζ Ori Aa is a highly variable star with both periodic and non-periodic variations, as well as episodic events. The rotation period we determined agrees well with the spectropolarimetric value from the literature. The changing activity level observed with BRITE could explain why the rotational modulation of the magnetic measurements was not clearly detected at all epochs. Based on data collected by the BRITE Constellation satellite mission, designed, built, launched, operated and supported by the Austrian Research Promotion Agency (FFG), the University of

  14. Diurnal and seasonal variability of gasoline-related volatile organic compound emissions in Riverside, California.

    Science.gov (United States)

    Gentner, Drew R; Harley, Robert A; Miller, Angela M; Goldstein, Allen H

    2009-06-15

    On- and off-road mobile sources are the dominant contributors to urban anthropogenic volatile organic compound (AVOC) emissions. Analyses of gasoline samples from California for both summer and winter indicate significant differences in liquid fuel and vapor chemical composition due to intentional seasonal adjustments. Ambient concentrations of 55 VOCs were measured via in situ gas chromatography in the 2005 Study of Organic Aerosols at Riverside (SOAR) during both summer and fall. A chemical mass balance analysis was used to differentiate vapor pressure-driven VOC emissions from other motor vehicle-related emissions such as tailpipe exhaust. Overall, fuel vapor emissions accounted for 31 +/- 2% of gasoline-related VOC in Riverside; California's emission factor model similarly estimates 31% of gasoline-related VOC emissions are fuel vapor. The diurnal pattern of vapor pressure-driven VOC source contributions is relatively stable around 10 microg/m3, while whole gasoline (i.e., tailpipe) contributions peak at approximately 60 microg/m3 during the morning commute. There is no peak in whole gasoline source contributions during the afternoon, due to rapid dilution associated with high mixing heights and wind speeds in the Riverside area. The relationship between estimated gasoline-related VOC and observed carbon monoxide concentrations in this study is similar to California's 2005 emission inventory; we calculated a VOC to CO mass ratio of 0.086 +/- 0.006 (95% CI) compared to 0.097 in the emission inventory for all gasoline-related sources.

  15. Global Structures and Multi-Temporal Variabilities of MLT Migrating Diurnal Tide

    Institute of Scientific and Technical Information of China (English)

    CHEN Ze-Yu; LU Da-Ren

    2008-01-01

    @@ Migrating diurnal tide in the MLT region is examined by the application of Hough mode decomposition with the tide delineated from the SABER/TIMED temperatures over 2002-2006. The decomposition results show that in the height range 60-100 km, the (1, 1) mode is the most predominant among eight leading Hough modes including four propagating and four trapped modes. It exhibits a sustained maximum at 97kin and significant semi-annual oscillation. Additionally, a novel feature of inter-annual variation with period of about two years is clearly seen in the (1, 1) mode, e.g., repeated maxima are seen at the March equinox of 2002, 2004 and 2006,respectively. This feature is further manifested by the tidal amplitudes in the height range 70-100 km in the height-time cross-section at the equator. It is likely of the QBO as the height range just coincides to where the zonal mean zonal winds derived by using the UARS data exhibiting the QBO. The other results show that the (1,2) mode is important at < 80 km exhibiting comparable amplitude to that of the (1, 1) mode, and in particular the nearly anti-correlation with the (1, 1) mode. The tide at about 85 km is suggested of rather complex as the four trapped modes exhibit maximum at these heights, which indicates the presence of local excitations or sources at below.

  16. Short-term variability and mass loss in Be stars. II. Physical taxonomy of photometric variability observed by the Kepler spacecraft

    Science.gov (United States)

    Rivinius, Th.; Baade, D.; Carciofi, A. C.

    2016-09-01

    Context. Classical Be stars have been established as pulsating stars. Space-based photometric monitoring missions contributed significantly to that result. However, whether Be stars are just rapidly rotating SPB or β Cep stars, or whether they have to be understood differently, remains debated in the view of their highly complex power spectra. Aims: Kepler data of three known Be stars are re-visited to establish their pulsational nature and assess the properties of additional, non-pulsational variations. The three program stars turned out to be one inactive Be star, one active, continuously outbursting Be star, and one Be star transiting from a non-outbursting into an outbursting phase, thus forming an excellent sample to distill properties of Be stars in the various phases of their life-cycle. Methods: The Kepler data was first cleaned from any long-term variability with Lomb-Scargle based pre-whitening. Then a Lomb-Scargle analysis of the remaining short-term variations was compared to a wavelet analysis of the cleaned data. This offers a new view on the variability, as it enables us to see the temporal evolution of the variability and phase relations between supposed beating phenomena, which are typically not visualized in a Lomb-Scargle analysis. Results: The short-term photometric variability of Be stars must be disentangled into a stellar and a circumstellar part. The stellar part is on the whole not different from what is seen in non-Be stars. However, some of the observed phenomena might be to be due to resonant mode coupling, a mechanism not typically considered for B-type stars. Short-term circumstellar variability comes in the form of either a group of relatively well-defined, short-lived frequencies during outbursts, which are called Štefl frequencies, and broad bumps in the power spectra, indicating aperiodic variability on a time scale similar to typical low-order g-mode pulsation frequencies, rather than true periodicity. Conclusions: From a

  17. Diurnal variability and biogeochemical reactivity of mercury species in an extreme high-altitude lake ecosystem of the Bolivian Altiplano.

    Science.gov (United States)

    Alanoca, L; Amouroux, D; Monperrus, M; Tessier, E; Goni, M; Guyoneaud, R; Acha, D; Gassie, C; Audry, S; Garcia, M E; Quintanilla, J; Point, D

    2016-04-01

    Methylation and demethylation represent major transformation pathways regulating the net production of methylmercury (MMHg). Very few studies have documented Hg reactivity and transformation in extreme high-altitude lake ecosystems. Mercury (Hg) species concentrations (IHg, MMHg, Hg°, and DMHg) and in situ Hg methylation (M) and MMHg demethylation (D) potentials were determined in water, sediment, floating organic aggregates, and periphyton compartments of a shallow productive Lake of the Bolivian Altiplano (Uru Uru Lake, 3686 m). Samples were collected during late dry season (October 2010) and late wet season (May 2011) at a north (NS) and a south (SS) site of the lake, respectively. Mercury species concentrations exhibited significant diurnal variability as influenced by the strong diurnal biogeochemical gradients. Particularly high methylated mercury concentrations (0.2 to 4.5 ng L(-1) for MMHgT) were determined in the water column evidencing important Hg methylation in this ecosystem. Methylation and D potentials range were, respectively, <0.1-16.5 and <0.2-68.3 % day(-1) and were highly variable among compartments of the lake, but always higher during the dry season. Net Hg M indicates that the influence of urban and mining effluent (NS) promotes MMHg production in both water (up to 0.45 ng MMHg L(-1) day(-1)) and sediment compartments (2.0 to 19.7 ng MMHg g(-1) day(-1)). While the sediment compartment appears to represent a major source of MMHg in this shallow ecosystem, floating organic aggregates (dry season, SS) and Totora's periphyton (wet season, NS) were found to act as a significant source (5.8 ng MMHg g(-1) day(-1)) and a sink (-2.1 ng MMHg g(-1) day(-1)) of MMHg, respectively. This work demonstrates that high-altitude productive lake ecosystems can promote MMHg formation in various compartments supporting recent observations of high Hg contents in fish and water birds.

  18. Spectroscopic and photometric observations of unidentified ultraviolet variable objects in the GUVV-2 Catalog

    Institute of Scientific and Technical Information of China (English)

    You Li; Jing Wang; Jian-Yan Wei; Xiang-Tao He

    2011-01-01

    An NUV-optical diagram composed from sources from the second Galaxy Evolution Explorer (GALEX) Ultraviolet Variability (GUVV-2) Catalog provides us with a method to tentatively classify the unknown GUVV-2 sources by their NUV-optical magnitudes. For the purpose of testing the correctness and generality of the method, we carry out a program on the spectroscopic observations of the unidentified GUVV-2 sources. The spectroscopic identification of these 37 sources are 19 type -A to -F stars, 10 type -G to -K stars and 7 M dwarf stars together with an AGN. We also present the light curves in the R-band for two RR Lyrae star candidates selected from the NUV-optical diagram, both of which undergo cyclic variations. Combining their light curves and colors, we classify them as RR Lyrae stars. To confirm the resuits, we show a color-color diagram for the 37 newly identified spectroscopic objects compared with previously identified ones, which are consistent with our previous results, indicating that the ultraviolet variable sources can initially be classified by their NUV/optical color-color diagram.

  19. Photometric study of selected cataclysmic variables II. Time-series photometry of nine systems

    CERN Document Server

    Papadaki, C; Stanishev, V; Boumis, P; Akras, S; Sterken, C

    2008-01-01

    We present time-series photometry of nine cataclysmic variables: EI UMa, V844Her, V751 Cyg, V516 Cyg, GZ Cnc, TY Psc, V1315 Aql, ASAS J002511+1217.12, V1315 Aql and LN UMa. The observations were conducted at various observatories, covering 170 hours and comprising 7,850 data points in total. For the majority of targets we confirm previously reported periodicities and for some of them we give, for the first time, their spectroscopic orbital periods. For those dwarf-nova systems which we observed during both quiescence and outburst, the increase in brightness was followed by a decrease in the amount of flickering. Quasi-periodic oscillations have either been discovered, or were confirmed. For the eclipsing system V1315 Aql we have covered 9 eclipses, and obtained a refined orbital ephemeris. We find that, during its long baseline of observations, no change in the orbital period of this system has occurred. V1315 Aql also shows eclipses of variable depth.

  20. Investigating the diurnal and spatial variability of flows in the atmospheric boundary layer: A large eddy simulation study

    Science.gov (United States)

    Kumar, Vijayant

    Large-eddy simulation (LES) studies of the atmospheric boundary layer (ABL) have historically modeled the daytime (convective), nighttime (stable) and dawn/dusk windy (neutral) regimes separately under the assumption of a quasi-steady ABL. The real-world ABL however, continuously transitions between the different stability regimes and development of an LES capable of simulating the entire diurnal evolution of the ABL is needed. We have developed an LES tool (The JHU-LES code) with the new-generation Lagrangian dynamic models capable of dynamic adjustment of the subgrid-scale stresses thereby, making it apt for LES over entire diurnal cycles of the ABL. Preliminary LES studies demonstrate that the JHU-LES code reproduces well-known features of the quasi-steady convective and stable boundary layers, such as the well-known spectral scalings for production and inertial subranges. LES of the entire 24-hour diurnal evolution of the atmospheric boundary layer is then performed and compared successfully to field observations (HATS dataset). Important features of the diurnal ABL such as entrainment-based growth of the CBL, development of the stable boundary layer and evolution of the nocturnal low-level jet are well reproduced. The advantages of using a local Obukhov length-scale to normalize the results are highlighted. To investigate the role of surface boundary conditions and geostrophic wind forcing, LES investigations of multi-day evolution of the ABL flow are then performed with several combinations of surface boundary conditions (imposed temperature and heat flux) and geostrophic forcing (constant, time-varying, time and height varying). The variable geostrophic forcing significantly improves the agreement of LES results with surface flux observations but shows poor agreement with daytime surface fluxes and, daytime and nighttime mean profiles. The LES setup using an imposed surface temperature almost always yields better results than cases where the heat flux is

  1. Photometric variability of the nova-like object V380 Oph in 1976-2016

    CERN Document Server

    Shugarov, S; Sokolovsky, K; Chochol, D

    2016-01-01

    We combined photographic, photoelectric and CCD observations of the nova-like variable V380 Oph to get a light curve spanning the time range of 40 years. While the typical high-state brightness of V380 Oph was R~14.5, two low-brightness episodes identified in 1979 (B_pg~17.5) and 2015 (R~19) confirm its classification as a VY Scl-type "anti-dwarf nova". The Fourier period analysis of photoelectric and CCD V and B observations obtained in 2002-16 revealed the presence of two periods 0.148167d and 4.287d, that may be associated with negative superhumps and disc precession. We also compared measurements obtained with the iris micro-photometer and flatbed scanner at the same plates and found an agreement within the expected accuracy of photographic photometry.

  2. Vertical structure and diurnal variability of ammonia exchange potential within an intensively managed grass canopy

    Directory of Open Access Journals (Sweden)

    B. Herrmann

    2009-01-01

    Full Text Available Stomatal ammonia compensation points (χs of grass species on a mixed fertilized grassland were determined by measurements of apoplastic [NH4+] and [H>+] in the field. Calculated χs values were compared with in-canopy atmospheric NH3 concentration (χa measurements.

    Leaf apoplastic [NH4+] increased by a factor of two from the lowest level in the canopy to the top level. Bulk leaf [NH4+] and especially [NO3] slightly increased at the bottom of the canopy and these concentrations were very high in senescent plant litter. Calculated χs values were below atmospheric χs at all canopy levels measured, indicating that the grassland was characterized by NH3 deposition before cutting. This was confirmed by the χa profile, showing the lowest χa close to the ground (15 cm above soil surface and an increase in χa with canopy height. Neither χs nor χa could be measured close to the soil surface, however, the [NH4+] in the litter material indicated a high potential for NH3 emission.

    A diurnal course in apoplastic [NH4+] was seen in the regrowing grass growing after cutting, with highest concentration around noon. Both apoplastic and tissue [NH4+] increased in young grass compared to tall grass. Following cutting, in-canopy gradients of atmospheric χa showed NH3 emission but since calculated χs values of the cut grass were still lower than atmospheric NH3 concentrations, the emissions could not entirely be explained by stomatal NH3 loss. High tissue [NH4+] in the senescent plant material indicated that this fraction constituted an NH3 source

  3. Application of the Geostationary Ocean Color Imager to Mapping the Diurnal and Seasonal Variability of Surface Suspended Matter in a Macro-Tidal Estuary

    Directory of Open Access Journals (Sweden)

    Zhixin Cheng

    2016-03-01

    Full Text Available Total suspended particulate matter (TSM in estuarine and coastal regions usually exhibits significant natural variations. The understanding of such variations is of great significance in coastal waters. The aim of this study is to investigate and assess the diurnal and seasonal variations of surface TSM distribution and its mechanisms in coastal waters based on Geostationary Ocean Color Imager (GOCI data. As a case study, dynamic variations of TSM in the macro-tidal Yalu River estuary (YRE of China were analysed. With regard to diurnal variability, there were usually two peaks of TSM in a tidal cycle corresponding to the maximum flood and ebb current. Tidal action appears to play a vital role in diurnal variations of TSM. Both the processes of tidal re-suspension and advection could be identified; however, the diurnal variation of TSM was mainly affected by a re-suspension process. In addition, spring-neap tides can affect the magnitude of TSM diurnal variations in the YRE. The GOCI-retrieved TSM results clearly showed the seasonal variability of surface TSM in this area, with the highest level occurring in winter and the lowest in summer. Moreover, although river discharge to the YRE was much greater in the wet season than the dry season, TSM concentrations were significantly higher in the dry season. Wind waves were considered to be the main factor affecting TSM seasonal variation in the YRE.

  4. Relating jet structure to photometric variability: the Herbig Ae star HD 163296

    CERN Document Server

    Ellerbroek, L E; Dougados, C; Cabrit, S; Sitko, M L; Sana, H; Kaper, L; de Koter, A; Klaassen, P D; Mulders, G D; Mendigutia, I; Grady, C A; Grankin, K; van Winckel, H; Bacciotti, F; Russell, R W; Lynch, D K; Hammel, H B; Beerman, L C; Day, A N; Huelsman, D M; Werren, C; Henden, A; Grindlay, J

    2014-01-01

    Herbig Ae/Be stars are intermediate-mass pre-main sequence stars surrounded by circumstellar dust disks. Some are observed to produce jets, whose appearance as a sequence of shock fronts (knots) suggests a past episodic outflow variability. This "jet fossil record" can be used to reconstruct the outflow history. We present the first optical to near-infrared (NIR) VLT/X-shooter spectra of the jet from the Herbig Ae star HD 163296. We determine physical conditions in the knots, as well as their kinematic "launch epochs". Knots are formed simultaneously on either side of the disk, with a regular interval of ~16 yr. The velocity dispersion versus jet velocity and the energy input are comparable in both lobes. However, the mass loss rate, velocity, and shock conditions are asymmetric. We find Mjet/Macc ~ 0.01-0.1, consistent with magneto-centrifugal jet launching models. No evidence for dust is found in the high-velocity jet, suggesting it is launched within the sublimation radius (<0.5 au). The jet inclination...

  5. The Lick AGN Monitoring Project: Photometric Light Curves and Optical Variability Characteristics

    CERN Document Server

    Walsh, Jonelle L; Bentz, Misty C; Barth, Aaron J; Baliber, Nairn; Li, Weidong; Stern, Daniel; Bennert, Vardha Nicola; Brown, Timothy M; Canalizo, Gabriela; Filippenko, Alexei V; Gates, Elinor L; Greene, Jenny E; Malkan, Matthew A; Sakata, Yu; Street, Rachel A; Treu, Tommaso; Woo, Jong-Hak; Yoshii, Yuzuru

    2009-01-01

    The Lick AGN Monitoring Project targeted 13 nearby Seyfert 1 galaxies with the intent of measuring the masses of their central black holes using reverberation mapping. The sample includes 12 galaxies selected to have black holes with masses roughly in the range 10^6-10^7 solar masses, as well as the well-studied AGN NGC 5548. In conjunction with a spectroscopic monitoring campaign, we obtained broad-band B and V images on most nights from 2008 February through 2008 May. The imaging observations were carried out by four telescopes: the 0.76-m Katzman Automatic Imaging Telescope (KAIT), the 2-m Multicolor Active Galactic Nuclei Monitoring (MAGNUM) telescope, the Palomar 60-in (1.5-m) telescope, and the 0.80-m Tenagra II telescope. Having well-sampled light curves over the course of a few months is useful for obtaining the broad-line reverberation lag and black hole mass, and also allows us to examine the characteristics of the continuum variability. In this paper, we discuss the observational methods and the ph...

  6. The Variability of the BRITE-est Wolf-Rayet star gamma Velorum. Photometric and Spectroscopic Evidence of Colliding Winds.

    Science.gov (United States)

    Richardson, Noel; St-Jean, Lucas; Moffat, Anthony F. J.; St. Louis, Nicole; Post Russell, Christopher Michael; Shenar, Tomer; Pablo, Herbert; Hill, Grant M.; Ramiaramanantsoa, Tahina; Hamaguchi, Kenji; Corcoran, Michael F.

    2017-01-01

    We report on the first results of an intensive photometric and spectroscopic campaign on the bright WC+O binary, gamma Velorum. The system was observed with two-color photometry with the BRITE-Constellation nanosatellites for six months, while we collected ~500 optical spectra in parallel from ground-based observatories. We report on the spectroscopic orbit and the evidence of colliding winds, both spectroscopically and photometrically. We find evidence of an inverse relationship between the orbital separation and the observed flux. Through a comparison with multiple spectra and the red/blue filter responses, we find that the flux excess seen photometrically is caused by the excess line emission at periastron. We have begun to quantify these variations and will compare them with smoothed-particle hydrodynamics simulations. We will further constrain these processes using XMM-Newton X-ray spectroscopy that will be obtained in late-2016 in parallel with further optical photometric and spectroscopic observations.

  7. Diurnal variability of polycyclic aromatic compound (PAC) concentrations: Relationship with meteorological conditions and inferred sources

    Science.gov (United States)

    Alam, Mohammed S.; Keyte, Ian J.; Yin, Jianxin; Stark, Christopher; Jones, Alan M.; Harrison, Roy M.

    2015-12-01

    Polycyclic aromatic hydrocarbons (PAH) and their nitro and oxy derivatives have been sampled every three hours over one week in winter at two sites in Birmingham UK. One site is heavily influenced by road traffic and is close to residential dwellings, while the other site is a background urban location at some distance from both sources of emission. The time series of concentrations has been examined along with the ratio of concentrations between the two sampling sites. A comparison of averaged diurnal profiles has shown different patterns of behaviour which has been investigated through calculating ratios of concentration at 18:00-21:00 h relative to that at 06:00-09:00 h. This allows identification of those compounds with a strong contribution to a traffic-related maximum at 06:00-09:00 h which are predominantly the low molecular weight PAHs, together with a substantial group of quinones and nitro-PAHs. Changes in partitioning between vapour and particulate forms are unlikely to influence the ratio as the mean temperature at both times was almost identical. Most compounds show an appreciable increase in concentrations in the evening which is attributed to residential heating emissions. Compounds dominated by this source show high ratios of 18:00-21:00 concentrations relative to 06:00-09:00 concentrations and include higher molecular weight PAH and a substantial group of both quinones and nitro-PAH. The behaviour of retene, normally taken as an indicator of biomass burning, is suggestive of wood smoke only being one contributor to the evening peak in PAH and their derivatives, with coal combustion presumably being the other main contributor. Variations of PAH concentrations with wind speed show a dilution behaviour consistent with other primary pollutants, and high concentrations of a range of air pollutants were observed in an episode of low temperatures and low wind speeds towards the end of the overall sampling period consistent with poor local dispersion

  8. Diurnal variability of heat fluxes and heat content at a few locations off central east coast of India during April 1989

    Digital Repository Service at National Institute of Oceanography (India)

    Sadhuram, Y.; Rao, B.P.; Rao, V.S.; Rao, T.V.N.

    Diurnal variability of surface wind speed, net heat exchange, sea surface temperature, vertical thermal structure and heat content at three locations, viz., station A (17 degrees 59'N, 83 degrees 53.9'E), station B (17 degrees 00'N, 82 degrees 32...

  9. Short-term variability and mass loss in Be stars II. Physical taxonomy of photometric variability observed by the Kepler spacecraft

    CERN Document Server

    Rivinius, Thomas; Carciofi, Alex

    2016-01-01

    Context: [abbreviated] Aims: Kepler data of three known Be stars are re-visited to establish their pulsational nature and assess the properties of additional, non-pulsational variations. The three program stars turned out to be one inactive Be star, one active, continuously outbursting Be star, and one Be star transiting from a non-outbursting into an outbursting phase, thus forming an excellent sample to distill properties of Be stars in the various phases of their life-cycle. Methods: [abbreviated] Results: The short-term photometric variability of Be stars must be disentangled into a stellar and a circumstellar part. The stellar part is on the whole not different from what is seen in non-Be stars. However, some of the observed phenomena might be to be due to resonant mode coupling, a mechanism not typically considered for B-type stars. Short-term circumstellar variability comes in the form of either a group of relatively well-defined, short-lived frequencies during outbursts, which are called \\v{S}tefl fre...

  10. Seasonal and diurnal variability of the meteor flux at high latitudes observed using PFISR

    Science.gov (United States)

    Sparks, J. J.; Janches, D.; Nicolls, M. J.; Heinselman, C. J.

    2009-05-01

    We report in this and a companion paper [Fentzke, J.T., Janches, D., Sparks, J.J., 2008. Latitudinal and seasonal variability of the micrometeor input function: A study using model predictions and observations from Arecibo and PFISR. Journal of Atmospheric and Solar-Terrestrial Physics, this issue, doi:10.1016/j.jastp.2008.07.015] a complete seasonal study of the micrometeor input function (MIF) at high latitudes using meteor head-echo radar observations performed with the Poker Flat Incoherent Scatter Radar (PFISR). This flux is responsible for a number of atmospheric phenomena; for example, it could be the source of meteoric smoke that is thought to act as condensation nuclei in the formation of ice particles in the polar mesosphere. The observations presented here were performed for full 24-h periods near the summer and winter solstices and spring and autumn equinoxes, times at which the seasonal variability of the MIF is predicted to be large at high latitudes [Janches, D., Heinselman, C.J., Chau, J.L., Chandran, A., Woodman, R., 2006. Modeling of the micrometeor input function in the upper atmosphere observed by High Power and Large Aperture Radars, JGR, 11, A07317, doi:10.1029/2006JA011628]. Precise altitude and radar instantaneous line-of-sight (radial) Doppler velocity information are obtained for each of the hundreds of events detected every day. We show that meteor rates, altitude, and radial velocity distributions have a large seasonal dependence. This seasonal variability can be explained by a change in the relative location of the meteoroid sources with respect to the observer. Our results show that the meteor flux into the upper atmosphere is strongly anisotropic and its characteristics must be accounted for when including this flux into models attempting to explain related aeronomical phenomena. In addition, the measured acceleration and received signal strength distribution do not seem to depend on season; which may suggest that these observed

  11. Diurnal variability in riverine dissolved organic matter composition determined by in situ optical measurement in the San Joaquin River (California, USA)

    Science.gov (United States)

    Spencer, R.G.M.; Pellerin, B.A.; Bergamaschi, B.A.; Downing, B.D.; Kraus, T.E.C.; Smart, D.R.; Dahlgren, R.A.; Hernes, P.J.

    2007-01-01

    Dissolved organic matter (DOM) concentration and composition in riverine and stream systems are known to vary with hydrological and productivity cycles over the annual and interannual time scales. Rivers are commonly perceived as homogeneous with respect to DOM concentration and composition, particularly under steady flow conditions over short time periods. However, few studies have evaluated the impact of short term variability (<1 day) on DOM dynamics. This study examined whether diurnal processes measurably altered DOM concentration and composition in the hypereutrophic San Joaquin River (California) during a relatively quiescent period. We evaluated the efficacy of using optical in situ measurements to reveal changes in DOM which may not be evident from bulk dissolved organic carbon (DOC) measurement alone. The in situ optical measurements described in this study clearly showed for the first time diurnal variations in DOM measurements, which have previously been related to both composition and concentration, even though diurnal changes were not well reflected in bulk DOC concentrations. An apparent asynchronous trend of DOM absorbance and chlorophyll-a in comparison to chromophoric dissolved organic matter (CDOM) fluorescence and spectral slope S290-350 suggests that no one specific CDOM spectrophotometric measurement explains absolutely DOM diurnal variation in this system; the measurement of multiple optical parameters is therefore recommended. The observed diurnal changes in DOM composition, measured by in situ optical instrumentation likely reflect both photochemical and biologically-mediated processes. The results of this study highlight that short-term variability in DOM composition may complicate trends for studies aiming to distinguish different DOM sources in riverine systems and emphasizes the importance of sampling specific study sites to be compared at the same time of day. The utilization of in situ optical technology allows short-term variability

  12. Power spectral analysis of heart rate variability for assessment of diurnal variation of autonomic nervous activity in guinea pigs.

    Science.gov (United States)

    Akita, Megumi; Ishii, Keiji; Kuwahara, Masayoshi; Tsubone, Hirokazu

    2002-01-01

    We established characteristics of power spectral analysis of heart rate variability, and assessed the diurnal variations of autonomic nervous function in guinea pigs. For this purpose, an electrocardiogram (ECG) was recorded for 24 hr from conscious and unrestrained guinea pigs using a telemetry system. There were two major spectral components, at low frequency (LF) and high frequency (HF) bands, in the power spectrum of HR variability. On the basis of these data, we defined two frequency bands of interest: LF (0.07-0.7 Hz) and HF (0.7-3.0 Hz). The power of LF was higher than that of HF in the normal guinea pigs. Atropine significantly reduced power at HF. Propranolol also significantly reduced power at LF. Furthermore, the decrease in the parasympathetic mechanism produced by atropine was reflected in a slight increase in the LF/HF ratio. The LF/HF ratio appeared to follow the reductions of sympathetic activity produced by propranolol. Autonomic blockade studies indicated that the HF component reflected parasympathetic activity and the LF/HF ratio seemed to be a convenient index of autonomic balance. Nocturnal patterns, in which the values of heart rate in the dark phase (20:00-06:00) were higher than those in the light phase (06:00-20:00), were observed. However, the HF, LF and the LF/HF ratio showed no daily pattern. These results suggest that the autonomic nervous function in guinea pigs has no clear circadian rhythmicity. Therefore, this information may be useful for future studies concerning the autonomic nervous function in this species.

  13. Diurnal variability of regional cloud and clear-sky radiative parameters derived from GOES data. I - Analysis method. II - November 1978 cloud distributions. III - November 1978 radiative parameters

    Science.gov (United States)

    Minnis, P.; Harrison, E. F.

    1984-01-01

    Cloud cover is one of the most important variables affecting the earth radiation budget (ERB) and, ultimately, the global climate. The present investigation is concerned with several aspects of the effects of extended cloudiness, taking into account hourly visible and infrared data from the Geostationary Operational Environmental Satelite (GOES). A methodology called the hybrid bispectral threshold method is developed to extract regional cloud amounts at three levels in the atmosphere, effective cloud-top temperatures, clear-sky temperature and cloud and clear-sky visible reflectance characteristics from GOES data. The diurnal variations are examined in low, middle, high, and total cloudiness determined with this methodology for November 1978. The bulk, broadband radiative properties of the resultant cloud and clear-sky data are estimated to determine the possible effect of the diurnal variability of regional cloudiness on the interpretation of ERB measurements.

  14. Variability and trends in daily minimum and maximum temperatures and in the diurnal temperature range in Lithuania, Latvia and Estonia in 1951-2010

    Science.gov (United States)

    Jaagus, Jaak; Briede, Agrita; Rimkus, Egidijus; Remm, Kalle

    2014-10-01

    Spatial distribution and trends in mean and absolute maximum and minimum temperatures and in the diurnal temperature range were analysed at 47 stations in the eastern Baltic region (Lithuania, Latvia and Estonia) during 1951-2010. Dependence of the studied variables on geographical factors (latitude, the Baltic Sea, land elevation) is discussed. Statistically significant increasing trends in maximum and minimum temperatures were detected for March, April, July, August and annual values. At the majority of stations, the increase was detected also in February and May in case of maximum temperature and in January and May in case of minimum temperature. Warming was slightly higher in the northern part of the study area, i.e. in Estonia. Trends in the diurnal temperature range differ seasonally. The highest increasing trend revealed in April and, at some stations, also in May, July and August. Negative and mostly insignificant changes have occurred in January, February, March and June. The annual temperature range has not changed.

  15. Diurnal and seasonal variability of TKE dissipation rate in the ABL over a tropical station using UHF wind profiler

    CSIR Research Space (South Africa)

    Kalapureddy, MCR

    2007-04-01

    Full Text Available This paper presents the diurnal and seasonal variation of Turbulence Kinetic Energy (TKE) dissipation rate (ε) in the Atmospheric Boundary-Layer (ABL) over a tropical station, Gadanki (13.5° N, 79.2° E) in India. Doppler spectral width measurements...

  16. Change in diurnal variations of meteorological variables induced by anthropogenic aerosols over the North China Plain in summer 2008

    Science.gov (United States)

    Gao, Yi; Zhang, Meigen; Liu, Xiaohong; Wang, Lili

    2016-04-01

    This study investigates the impacts of all anthropogenic aerosols and anthropogenic black carbon (BC) on the diurnal variations of meteorological variables in the atmospheric boundary layer over the North China Plain (NCP) during June to August 2008, using a coupled meteorology and chemistry model (WRF-Chem). The results of the ensemble numerical experiments show that surface air temperature decreases by about 0.6 to 1.2 K with the maximum decrease over the Beijing urban area and the southern part of Hebei province, and the surface relative humidity (RH) increases by 2-4 % owing to all anthropogenic aerosols. On the contrary, anthropogenic BC induces a small change of temperature and RH at surface. Averaged for Beijing, Tianjin, and Hebei province (BTH region) and High Particle Concentration (HPC) periods when PM2.5 surface concentration is more than 60 μg m-3 and daily AOD is more than 0.9, all anthropogenic aerosols decrease air temperature under 850 hPa and increase it between 500 and 850 hPa, while anthropogenic BC increases it for whole atmosphere. The maximum changes occur at 08:00-20:00 (local time). Aerosol-induced surface energy and diabatic heating change leads to a cooling at the surface and in the lower atmosphere and a warming in the middle troposphere at 08:00-17:00, with reversed effects at 20:00-05:00. BC cools the atmosphere at the surface and warms the atmosphere above for the whole day. As a result, the equivalent potential temperature profile change shows that the lower atmosphere is more stable at 08:00 and 14:00. All anthropogenic aerosols decrease the surface wind speed by 20-60 %, while anthropogenic BC decreases the wind speed by 10-40 % over the NCP with the maximum decrease at 08:00. The aerosol-induced stabilization of the lower atmosphere favors the accumulation of air pollutants and thus contributes to deterioration of visibility and fog-haze events.

  17. Physical parameters and long-term photometric variability of V1481 Ori, a SB2 member of Orion Nebula Cluster with an accreting component

    CERN Document Server

    Messina, Sergio; Biazzo, Katia; Lanza, Antonino F; Distefano, Elisa; Melo, Claudio H F; Bradstreet, David; Herbst, William

    2015-01-01

    We present the results of our analysis on V1481 Ori (JW 239), a young SB2 in the Orion Nebula Cluster with a circumbinary disc accreting on the lower-mass component. The analysis is based on high-resolution spectroscopic data and high-quality photometric time series about 20-yr long. Thanks to the spectroscopy, we confirm the binary nature of this system consisting of M3 + M4 components and derive the mass ratio M_B/M_A = 0.54, a variable luminosity ratio L_B/L_A = 0.68--0.94, and an orbital period P_orb = 4.433d. The photometric data allowed us to measure the rotation periods of the two components P_phot = 4.4351d and they are found to be synchronized with the orbital period. The simultaneous modeling of V-, I-band, and radial velocity curves in the 2005 season suggests that the variability is dominated by one hot spot on the secondary component covering at least about 3.5% of the stellar surface and about 420K hotter than the unperturbed photosphere. Such a spot may originate from the material of the circum...

  18. Constraints on the optical polarization source in the luminous non-blazar quasar 3C 323.1 (PG 1545+210) from the photometric and polarimetric variability

    Science.gov (United States)

    Kokubo, Mitsuru

    2017-01-01

    We examine the optical photometric and polarimetric variability of the luminous type 1 non-blazar quasar 3C 323.1 (PG 1545+210). Two optical spectro-polarimetric measurements taken during the periods 1996-98 and 2003 combined with a V-band imaging polarimetric measurement taken in 2002 reveal that (1) as noted in the literature, the polarization of 3C 323.1 is confined only to the continuum emission, that is, the emission from the broad line region is unpolarized; (2) the polarized flux spectra show evidence of a time-variable broad absorption feature in the wavelength range of the Balmer continuum and other recombination lines; (3) weak variability in the polarization position angle (PA) of ˜ 4 deg over a time-scale of 4-6 years is observed; and (4) the V-band total flux and the polarized flux show highly correlated variability over a time-scale of one year. Taking the above-mentioned photometric and polarimetric variability properties and the results from previous studies into consideration, we propose a geometrical model for the polarization source in 3C 323.1, in which an equatorial absorbing region and an axi-asymmetric equatorial electron-scattering region are assumed to be located between the accretion disc and the broad line region. The scattering/absorbing regions can perhaps be attributed to the accretion disc wind or flared disc surface, but further polarimetric monitoring observations for 3C 323.1 and other quasars with continuum-confined polarization are needed to probe the true physical origins of these regions.

  19. Diurnal variability of upper ocean temperature and heat budget in the southern Bay of Bengal during October — November, 1998 (BOBMEX-Pilot)

    Indian Academy of Sciences (India)

    V S N Murty; V Ramesh Babu; L V G Rao; Charuta V Prabhu; V Tilvi

    2000-06-01

    Time-series data on upper-ocean temperature, Vessel-Mounted Acoustic Doppler Current Profiler (VM-ADCP) measured currents and surface meteorological parameters have been obtained for the first time in the southern Bay of Bengal at 7° N, 10° N, and 13° N locations along 87° E during October - November, 1998 under BOBMEX-Pilot programme. These data have been analysed to examine the diurnal variability of upper oceanic heat budget and to estimate the eddy diffusivity coefficient of heat in the upper layer. Diurnal variation of near-surface temperature is typical at northern location (13°N) with a range of 0.5°C while the diurnal range of temperature is enhanced to 0.8°C at the central location (10° N) due to intense solar radiation (1050 W/m2), clear skies and low wind speeds. At the southern location (7°N), the diurnal variation of temperature is atypical with the minimum temperature occurring at 2000 hrs instead of at early morning hours. In general, the diurnal curve of temperature penetrated up to 15 to 20 m with decreasing diurnal range with depth. The VM-ADCP measured horizontal currents in the upper ocean were predominantly easterly/northeasterly at southern location, north/northerly at central location and northwesterly at northern location, thus describing a large-scale cyclonic gyre with the northward meridional flow along 87°E. The magnitudes of heat loss at the surface due to air-sea heat exchanges and in the upper 50 m layer due to vertical diffusion of heat are highest at the southern location where intense convective activity followed by overcast skies and synoptic disturbance prevailed in the lower atmosphere. This and the estimated higher value (0.0235 m2/s) of eddy diffusivity coefficient of heat in the upper ocean (0-50 m depth) suggest that 1-D processes controlled the upper layer heat budget at the southern location. On the other hand, during the fair weather conditions, at the central and northern locations, the upper layer gained heat

  20. Effects of diurnal variation on the Test of Variables of Attention performance in young adults with attention-deficit/hyperactivity disorder.

    Science.gov (United States)

    Hunt, Melissa G; Bienstock, Solomon W; Qiang, Judy Kexin

    2012-03-01

    The Test of Variables of Attention (TOVA) is a continuous performance test that assesses attention, impulsivity, and processing speed. Continuous performance tests are used in the assessment of attention-deficit/hyperactivity disorder (ADHD) in children and adults. TOVA norms are based on a morning administration, and any TOVA administered after 1:00 p.m. is flagged as potentially invalid. Whereas the testing time recommendations make sense for pediatric samples, it is unclear whether they are appropriate for young adults, who typically show significant phase delay in their diurnal rhythms. The current study explores the impact of time of day on TOVA performance in young adults with ADHD. Participants were randomly assigned to either morning or afternoon administration. We found no significant diurnal variation in TOVA performance. We also found no interaction between diurnal preference and time of day of administration. Night owls endorsed more inattention symptoms on a self-report measure than more intermediate individuals but actually made significantly fewer omission (inattention) errors on the TOVA. Self-reported symptoms of inattention showed moderate, significant correlations with various TOVA performance indices. Self-reported symptoms of hyperactivity and impulsivity, however, showed no relationship to TOVA performance. These results suggest that the TOVA can be administered to adults with ADHD outside of the hours recommended in the manual without significantly compromising the interpretative validity of test score interpretation. Thus, a TOVA report that is consistent with ADHD should not be dismissed simply because it was administered in the late afternoon.

  1. Impact of atmospheric boundary layer depth variability and wind reversal on the diurnal variability of aerosol concentration at a valley site

    Energy Technology Data Exchange (ETDEWEB)

    Pal, S., E-mail: sp5hd@Virginia.EDU; Lee, T.R.; Phelps, S.; De Wekker, S.F.J.

    2014-10-15

    concentration variability • Only accumulation mode particles are affected by boundary layer dilution effect. • Effect of wind reversal in a valley on the diurnal cycle of particle concentrations. • Decreasing trend in the boundary layer depths resulted in an increasing trend in aerosol concentration. • Effect of boundary layer depth growth rate on aerosol concentration.

  2. Highly resolved diurnal trends in natural variability of coral reef carbon budgets, Palau, Western Pacific, using a new automated continuous flow system

    Science.gov (United States)

    Teneva, L. T.; Dunbar, R. B.; Mucciarone, D. A.; Fleischfresser, J. D.

    2011-12-01

    There is growing evidence that ocean acidification (OA) will have significantly detrimental impacts on coral reef calcification and community composition. However, the rates of coral reef response to ocean pH changes and the implications of for ecosystem resilience remain largely unknown. Our ability to make more accurate predictions of OA impacts on coral reefs hinges on an improved capacity for temporal and spatial measurements of coral reef carbon budgets. Here we report on in situ results from a 6 day deployment during April 2011 over a Palauan coral reef. Our experimental approach uses a custom-made automated continuous flow system capable of resolving pH, temperature, and salinity on a 10-second timescale, and Dissolved Inorganic Carbon (DIC) on a 5-minute timescale. In addition, discrete water samples were collected for alkalinity measurements every 3-4 hours in order to capture the essential carbonate variables. We observe higher diurnal amplitude in the DIC and alkalinity signal that is commensurate with greater diurnal tidal range. The highest diurnal alkalinity signal of 100 umol/kg was observed on the first day of the experiment and it progressively decreased throughout the week to 50 umol/kg. A similar trend occurred with DIC, with highest diurnal DIC of 250 umol/kg, decreasing to 100 umol/kg at the end of deployment. Maxima in DIC and alkalinity occurred around 10-11am, and minima occurred near dusk. The diurnal signal in pH ranged 8.0-8.1, with semidiurnal maxima at 2-3am and again~12 hours later. Conversely, minima occurred in mid-morning and again at ~10pm. Our results clearly demonstrate that coral community calcification and photosynthesis affect the surrounding waters' carbon chemistry. In this setting, however, the hydrodynamics - in particular, strong tidal influence -are likely the most significant factor determining the carbon chemistry conditions within the reef community. Highly-resolved natural variability in coral reef metabolism from

  3. Spatial Variability of the Background Diurnal Cycle of Deep Convection around the GoAmazon2014/5 Field Campaign Sites

    Energy Technology Data Exchange (ETDEWEB)

    Burleyson, Casey D.; Feng, Zhe; Hagos, Samson M.; Fast, Jerome; Machado, Luiz A. T.; Martin, Scot T.

    2016-07-01

    The Amazon rainforest is one of a few regions of the world where continental tropical deep convection occurs. The Amazon’s isolation makes it challenging to observe, but also creates a unique natural laboratory to study anthropogenic impacts on clouds and precipitation in an otherwise pristine environment. Extensive measurements were made upwind and downwind of the large city of Manaus, Brazil during the Observations and Modeling of the Green Ocean Amazon 2014-2015 (GoAmazon2014/5) field campaign. In this study, 15 years of high-resolution satellite data are analyzed to examine the spatial and diurnal variability of convection occurring around the GoAmazon2014/5 sites. Interpretation of anthropogenic differences between the upwind (T0) and downwind (T1-T3) sites is complicated by naturally-occurring spatial variability between the sites. During the rainy season, the inland propagation of the previous day’s sea-breeze front happens to be in phase with the background diurnal cycle near Manaus, but is out of phase elsewhere. Enhanced convergence between the river-breezes and the easterly trade winds generates up to 10% more frequent deep convection at the GoAmazon2014/5 sites east of the river (T0a, T0t/k, and T1) compared to the T3 site which was located near the western bank. In general, the annual and diurnal cycles during 2014 were representative of the 2000-2013 distributions. The only exceptions were in March when the monthly mean rainrate was above the 95th percentile and September when both rain frequency and intensity were suppressed. The natural spatial variability must be accounted for before interpreting anthropogenically-induced differences among the GoAmazon2014/5 sites.

  4. Preliminary results from the ESA STSE project on SST diurnal variability, its regional extent and implications in atmospheric modelling (SSTDV:R.EX.–IM.A.M.)

    DEFF Research Database (Denmark)

    Karagali, Ioanna; Hasager, Charlotte Bay; Høyer, Jacob L.

    2013-01-01

    This study presents some preliminary results of the ESA Support To Science Element (STSE) funded project on the Diurnal Variability of the Sea Surface Temperature, regarding its Regional Extend and Implications in Atmospheric Modelling (SSTDV:R.EX.–IM.A.M.). Comparisons of SEVIRI SST with AATSR......, the 1-dimensional General Ocean Turbulence Model (GOTM) is applied. Preliminary results show that the initial temperature and salinity profiles may give a warmer start-up in the model while the light extinction scheme is a controlling factor for the amplitude and vertical extend of the daily signal....

  5. Assessing the diurnal variability of pharmaceutical and personal care products in a full-scale activated sludge plant

    Energy Technology Data Exchange (ETDEWEB)

    Salgado, R. [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); ESTS-IPS, Escola Superior de Tecnologia de Setubal do Instituto Politecnico de Setubal, Rua Vale de Chaves, Campus do IPS, Estefanilha, 2910-761 Setubal (Portugal); Marques, R. [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Instituto de Biologia Experimental e Tecnologica (IBET), Av. da Republica (EAN), 2784-505 Oeiras (Portugal); Noronha, J.P. [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Mexia, J.T. [Center of Mathematic Applications, Mathematics Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Carvalho, G. [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Instituto de Biologia Experimental e Tecnologica (IBET), Av. da Republica (EAN), 2784-505 Oeiras (Portugal); Oehmen, A., E-mail: adriano@dq.fct.unl.pt [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Reis, M.A.M. [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal)

    2011-10-15

    An intensive sampling campaign has been carried out in a municipal wastewater treatment plant (WWTP) to assess the dynamics of the influent pharmaceutical active compounds (PhAC) and musks. The mass loadings of these compounds in wastewater influents displayed contrasting diurnal variations depending on the compound. The musks and some groups of PhACs tended to follow a similar diurnal trend as compared to macropollutants, while the majority of PhACs followed either the opposite trend or no repeatable trend. The total musk loading to the WWTP was 0.74 {+-} 0.25 g d{sup -1}, whereas the total PhAC mass loading was 84.7 {+-} 63.8 g d{sup -1}. Unlike the PhACs, the musks displayed a high repeatability from one sampling day to the next. The range of PhAC loadings in the influent to WWTPs can vary several orders of magnitude from one day or week to the next, representing a challenge in obtaining data for steady-state modelling purposes. - Highlights: > Investigated the variations in influent wastewater pharmaceutical and musk loadings. > A high number of different pharmaceutical and musk compounds was analysed. > Many pharmaceutical groups displayed different characteristic patterns. > A representative steady-state pattern was observable for musks, not pharmaceuticals. > The results are relevant to the design of sampling campaigns for modelling purposes. - The diurnal variations of pharmaceuticals and musks were studied in an activated sludge plant, where the loadings of the musks were more repeatable than the pharmaceuticals.

  6. Ecotypic variability in the metabolic response of seeds to diurnal hydration-dehydration cycles and its relationship to seed vigor.

    Science.gov (United States)

    Bai, Bing; Sikron, Noga; Gendler, Tanya; Kazachkova, Yana; Barak, Simon; Grafi, Gideon; Khozin-Goldberg, Inna; Fait, Aaron

    2012-01-01

    Seeds in the seed bank experience diurnal cycles of imbibition followed by complete dehydration. These conditions pose a challenge to the regulation of germination. The effect of recurring hydration-dehydration (Hy-Dh) cycles were tested on seeds from four Arabidopsis thaliana accessions [Col-0, Cvi, C24 and Ler]. Diurnal Hy-Dh cycles had a detrimental effect on the germination rate and on the final percentage of germination in Col-0, Cvi and C24 ecotypes, but not in the Ler ecotype, which showed improved vigor following the treatments. Membrane permeability measured by ion conductivity was generally increased following each Hy-Dh cycle and was correlated with changes in the redox status represented by the GSSG/GSH (oxidized/reduced glutathione) ratio. Among the ecotypes, Col-0 seeds displayed the highest membrane permeability, whilst Ler was characterized by the greatest increase in electrical conductivity following Hy-Dh cycles. Following Dh 2 and Dh 3, the respiratory activity of Ler seeds significantly increased, in contrast to the other ecotypes, indicative of a dramatic shift in metabolism. These differences were associated with accession-specific content and patterns of change of (i) cell wall-related laminaribiose and mannose; (ii) fatty acid composition, specifically of the unsaturated oleic acid and α-linoleic acid; and (iii) asparagine, ornithine and the related polyamine putrescine. Furthermore, in the Ler ecotype the content of the tricarboxylic acid (TCA) cycle intermediates fumarate, succinate and malate increased in response to dehydration, in contrast to a decrease in the other three ecotypes. These findings provide a link between seed respiration, energy metabolism, fatty acid β-oxidation, nitrogen mobilization and membrane permeability and the improved germination of Ler seeds following Hy-Dh cycles.

  7. Photometric Variability in Kepler Target Stars. II. An Overview of Amplitude, Periodicity, and Rotation in First Quarter Data

    CERN Document Server

    Basri, Gibor; Batalha, Natalie; Gilliland, Ronald L; Jenkins, Jon; Borucki, William J; Koch, David; Caldwell, Doug; Dupree, Andrea K; Latham, David W; Marcy, Geoffrey W; Meibom, Soeren; Howell, Steve; Brown, Tim

    2010-01-01

    We provide an overview of stellar variability in the first quarter of data from the Kepler mission. The intent of this paper is to examine the entire sample of over 150,000 target stars for periodic behavior in their lightcurves, and relate this to stellar characteristics. These data constitute an unprecedented study of stellar variability given its great precision and complete time coverage (with a half hour cadence). Because the full Kepler pipeline is not currently suitable for a study of stellar variability of this sort, we describe our procedures for treating the "raw" pipeline data. About half of the total sample exhibits convincing periodic variability up to two weeks, with amplitudes ranging from differential intensity changes less than 10^{-4} up to more than 10 percent. K and M dwarfs have a greater fraction of period behavior than G dwarfs. The giants in the sample have distinctive quasi-periodic behavior, but are not periodic in the way we define it. Not all periodicities are due to rotation, and ...

  8. A Study of Stellar Photometric Variability Within the Central 4 pc of the Galactic Center with Infrared Image Subtraction

    CERN Document Server

    Peeples, Molly S; De Poy, D L

    2007-01-01

    We present a catalog of 110 variable stars within ~1' of Sgr A* based on image subtraction of near-infrared (H and K) photometry. Our images were obtained over 133 nights from 2000--2002 in H-band and over 134 nights from 2001--2002 in K-band; the typical FWHM is 1.4''. We match the catalog to other near-infrared, X-ray, and radio (i.e., maser) data, and we discuss some of the more interesting objects. The catalog includes 14 periodic sources, several known long-period variables and three new LPV candidates. We associate IRS 10* with OH, SiO, and H2O masers and a bright X-ray point source; this analysis suggests IRS 10* is an AGB star with an accreting companion. Among the approximately 90 newly discovered sources are a probable cataclysmic variable, a potential edge-on contact 84 day period eclipsing binary, and a possible 41 day period pulsating variable.

  9. New Variable Stars Discovered by Data Mining Images Taken During Recent Asteroid Photometric Observations. Results from the Year 2015

    Science.gov (United States)

    Papini, R.; Franco, L.; Marchini, A.; Salvaggio, F.

    2015-12-01

    During the past year the authors observed several asteroids for the purpose of determining the rotational period. Typically, this task requires a time series images acquisition on a single field for all the night, weather permitting, for a few nights although not consecutive. Routinely checking this "goldmine," allowed us to discover 14 variable stars not yet listed in catalogs or databases. While the most of the new variables are eclipsing binaries (GSC 01394-01889, GSC 00853-00371, CSS_J171124.7-004042, GSC05065-00218, UCAC4-386-142199, UCAC4 398-127457, UCAC4 384-148138, UCAC4 398-127590, UCAC4-383-155837, GSC-05752-01113, GSC 05765-01271), a few belong to RR Lyrae class (UCAC4 388-136835, 2MASS J20060657-1230376, UCAC4 386-142583). Since asteroid work is definitely time-consuming, follow-up is quite a difficult task for a small group. Further observations of these new variables are therefore strongly encouraged in order to better characterize these stars, especially RR Lyrae ones whose data combined with those taken during professional surveys seem to suggest the presence of a Blazhko effect.

  10. Photometric multi-site campaign on the open cluster NGC 884 I. Detection of the variable stars

    CERN Document Server

    Saesen, S; Pigulski, A; Aerts, C; Handler, G; Narwid, A; Fu, J N; Zhang, C; Jiang, X J; Vanautgaerden, J; Kopacki, G; Stȩślicki, M; Acke, B; Poretti, E; Uytterhoeven, K; Gielen, C; Østensen, R; De Meester, W; Reed, M D; Kołaczkowski, Z; Michalska, G; Schmidt, E; Yakut, K; Leitner, A; Kalomeni, B; Cherix, M; Spano, M; Prins, S; Van Helshoecht, V; Zima, W; Huygen, R; Vandenbussche, B; Lenz, P; Ladjal, D; Antolín, E Puga; Verhoelst, T; De Ridder, J; Niarchos, P; Liakos, A; Lorenz, D; Dehaes, S; Reyniers, M; Davignon, G; Kim, S -L; Kim, D H; Lee, Y -J; Lee, C -U; Kwon, J -H; Broeders, E; Van Winckel, H; Vanhollebeke, E; Waelkens, C; Raskin, G; Blom, Y; Eggen, J R; Degroote, P; Beck, P; Puschnig, J; Schmitzberger, L; Gelven, G A; Steininger, B; Blommaert, J; Drummond, R; Briquet, M; Debosscher, J

    2010-01-01

    CONTEXT: Recent progress in the seismic interpretation of field beta Cep stars has resulted in improvements of the physics in the stellar structure and evolution models of massive stars. Further asteroseismic constraints can be obtained from studying ensembles of stars in a young open cluster, which all have similar age, distance and chemical composition. AIMS: To improve our comprehension of the beta Cep stars, we studied the young open cluster NGC 884 to discover new B-type pulsators, besides the two known beta Cep stars, and other variable stars. METHODS: An extensive multi-site campaign was set up to gather accurate CCD photometry time series in four filters (U, B, V, I) of a field of NGC884. Fifteen different instruments collected almost 77500 CCD images in 1286 hours. The images were calibrated and reduced to transform the CCD frames into interpretable differential light curves. Various variability indicators and frequency analyses were applied to detect variable stars in the field. Absolute photometry ...

  11. The 2003-4 multisite photometric campaign for the Beta Cephei and eclipsing star 16 (EN) Lacertae with an Appendix on 2 Andromedae, the variable comparison star

    CERN Document Server

    Jerzykiewicz, M; Daszynska-Daszkiewicz, J; Pigulski, A; Poretti, E; Rodriguez, E; Amado, P J; Kolaczkowski, Z; Uytterhoeven, K; Dorokhova, T N; Dorokhov, N I; Lorenz, D; Zsuffa, D; Kim, S -L; Bourge, P -O; Acke, B; De Ridder, J; Verhoelst, T; Drummond, R; Movchan, A I; Lee, J -A; Steslicki, M; Molenda-Zakowicz, J; Garrido, R; Kim, S -H; Michalska, G; Paparo, M; Antoci, V; Aerts, C

    2015-01-01

    A multisite photometric campaign for the Beta Cephei and eclipsing variable 16 Lacertae is reported. 749 h of high-quality differential photoelectric Stromgren, Johnson and Geneva time-series photometry were obtained with ten telescopes during 185 nights. After removing the pulsation contribution, an attempt was made to solve the resulting eclipse light curve by means of the computer program EBOP. Although a unique solution was not obtained, the range of solutions could be constrained by comparing computed positions of the secondary component in the Hertzsprung-Russell diagram with evolutionary tracks. For three high-amplitude pulsation modes, the uvy and the Geneva UBG amplitude ratios are derived and compared with the theoretical ones for spherical-harmonic degrees l <= 4. The highest degree, l = 4, is shown to be incompatible with the observations. One mode is found to be radial, one is l = 1, while in the remaining case l = 2 or 3. The present multisite observations are combined with the archival photo...

  12. Effects of Diurnal Variation and Caffeine Consumption on Test of Variables of Attention (TOVA) Performance in Healthy Young Adults

    Science.gov (United States)

    Hunt, Melissa G.; Momjian, Ani J.; Wong, Keri K.

    2011-01-01

    The Test of Variables of Attention (TOVA) is a continuous performance test (CPT) that assesses attention, impulsivity, and processing speed. CPTs are used in the assessment of attention-deficit/hyperactivity disorder (ADHD) in children, but more young adults are being assessed for ADHD as well. The TOVA norms are based on a standardization sample…

  13. Job Strain and the Cortisol Diurnal Cycle in MESA: Accounting for Between- and Within-Day Variability.

    Science.gov (United States)

    Rudolph, Kara E; Sánchez, Brisa N; Stuart, Elizabeth A; Greenberg, Benjamin; Fujishiro, Kaori; Wand, Gary S; Shrager, Sandi; Seeman, Teresa; Diez Roux, Ana V; Golden, Sherita H

    2016-03-01

    Evidence of the link between job strain and cortisol levels has been inconsistent. This could be due to failure to account for cortisol variability leading to underestimated standard errors. Our objective was to model the relationship between job strain and the whole cortisol curve, accounting for sources of cortisol variability. Our functional mixed-model approach incorporated all available data-18 samples over 3 days-and uncertainty in estimated relationships. We used employed participants from the Multi-Ethnic Study of Atherosclerosis Stress I Study and data collected between 2002 and 2006. We used propensity score matching on an extensive set of variables to control for sources of confounding. We found that job strain was associated with lower salivary cortisol levels and lower total area under the curve. We found no relationship between job strain and the cortisol awakening response. Our findings differed from those of several previous studies. It is plausible that our results were unique to middle- to older-aged racially, ethnically, and occupationally diverse adults and were therefore not inconsistent with previous research among younger, mostly white samples. However, it is also plausible that previous findings were influenced by residual confounding and failure to propagate uncertainty (i.e., account for the multiple sources of variability) in estimating cortisol features.

  14. Effects of Diurnal Variation and Caffeine Consumption on Test of Variables of Attention (TOVA) Performance in Healthy Young Adults

    Science.gov (United States)

    Hunt, Melissa G.; Momjian, Ani J.; Wong, Keri K.

    2011-01-01

    The Test of Variables of Attention (TOVA) is a continuous performance test (CPT) that assesses attention, impulsivity, and processing speed. CPTs are used in the assessment of attention-deficit/hyperactivity disorder (ADHD) in children, but more young adults are being assessed for ADHD as well. The TOVA norms are based on a standardization sample…

  15. The 2003-2004 multisite photometric campaign for the β Cephei and eclipsing star 16 (EN) Lacertae with an appendix on 2 Andromedae, the variable comparison star

    Science.gov (United States)

    Jerzykiewicz, M.; Handler, G.; Daszyńska-Daszkiewicz, J.; Pigulski, A.; Poretti, E.; Rodríguez, E.; Amado, P. J.; Kołaczkowski, Z.; Uytterhoeven, K.; Dorokhova, T. N.; Dorokhov, N. I.; Lorenz, D.; Zsuffa, D.; Kim, S.-L.; Bourge, P.-O.; Acke, B.; De Ridder, J.; Verhoelst, T.; Drummond, R.; Movchan, A. I.; Lee, J.-A.; Stȩślicki, M.; Molenda-Żakowicz, J.; Garrido, R.; Kim, S.-H.; Michalska, G.; Paparó, M.; Antoci, V.; Aerts, C.

    2015-11-01

    A multisite photometric campaign for the β Cephei and eclipsing variable 16 Lacertae is reported. 749 h of high-quality differential photoelectric Strömgren, Johnson and Geneva time series photometry were obtained with 10 telescopes during 185 nights. After removing the pulsation contribution, an attempt was made to solve the resulting eclipse light curve by means of the computer program EBOP. Although a unique solution was not obtained, the range of solutions could be constrained by comparing computed positions of the secondary component in the Hertzsprung-Russell diagram with evolutionary tracks. For three high-amplitude pulsation modes, the uvy and the Geneva UBG amplitude ratios are derived and compared with the theoretical ones for spherical-harmonic degrees ℓ ≤ 4. The highest degree, ℓ = 4, is shown to be incompatible with the observations. One mode is found to be radial, one is ℓ = 1, while in the remaining case ℓ = 2 or 3. The present multisite observations are combined with the archival photometry in order to investigate the long-term variation of the amplitudes and phases of the three high-amplitude pulsation modes. The radial mode shows a non-sinusoidal variation on a time-scale of 73 yr. The ℓ = 1 mode is a triplet with unequal frequency spacing, giving rise to two beat-periods, 720.7 d and 29.1 yr. The amplitude and phase of the ℓ = 2 or 3 mode vary on time-scales of 380.5 d and 43 yr. The light variation of 2 And, one of the comparison stars, is discussed in the appendix.

  16. Forcing mechanisms governing diurnal, seasonal, and interannual variability in the boundary layer depths: Five years of continuous lidar observations over a suburban site near Paris

    Science.gov (United States)

    Pal, Sandip; Haeffelin, Martial

    2015-12-01

    The atmospheric boundary layer (ABL) depth, zi, is a fundamental variable of ABL and a climatologically important quantity. The exchange of energy between the Earth's surface and the atmosphere is governed by turbulent mixing processes in the daytime ABL, and thus, zi is important for scaling turbulence and diffusion in both meteorological and air quality models. A long-term data set of zi was derived at the Site Instrumental de Recherche par Télédétection Atmosphérique (SIRTA) observatory near Paris, using measurements obtained from a ground-based vertically pointing aerosol lidar and an autonomous algorithm STRAT+. Using multiparameter observational data sets covering a 5 year period (October 2008 to September 2013), this study aims to explore two interconnected ABL research topics: brief climatology involving multiscale temporal zi variability (diurnal, seasonal, annual, and interannual) and the relationship between zi and near-surface thermodynamic parameters to determine meteorological processes governing zi variability. Both the zi and the growth rate over SIRTA showed large seasonal variability with higher mean values in spring (1633 m and 225 m h-1) and summer (1947 m and 247 m h-1) than in autumn (1439 m and 196 m h-1) and winter (1033 m and 149 m h-1). Seasonal variability of daytime maximum zi is found to be strongly and linearly correlated with downwelling solar radiation at the surface (r = 0.92), while the dependence between daytime maximum zi and sensible heat flux (SHF) at seasonal scales is not fully linear, in particular, for summer months. Interannual variability is studied using deseasonalized monthly-mean anomalies of each variable. Conditional sampling and linear regression analyses between the anomalies of deseasonalized SHF and daytime maximum zi, show (1) stronger correlation between the two parameters for the soil conditions compared to the wet soil conditions, (2) that zi anomalies were more dependent on SHF anomalies for negative

  17. The spatial variability of water chemistry and DOC in bog pools: the importance of slope position, diurnal turnover and pool type

    Science.gov (United States)

    Holden, Joseph; Turner, Ed; Baird, Andy; Beadle, Jeannie; Billett, Mike; Brown, Lee; Chapman, Pippa; Dinsmore, Kerry; Dooling, Gemma; Grayson, Richard; Moody, Catherine; Gee, Clare

    2017-04-01

    We have previously shown that marine influence is an important factor controlling regional variability of pool water chemistry in blanket peatlands. Here we examine within-site controls on pool water chemistry. We surveyed natural and artificial (restoration sites) bog pools at blanket peatland sites in northern Scotland and Sweden. DOC, pH, conductivity, dissolved oxygen, temperature, cations, anions and absorbance spectra from 220-750nm were sampled. We sampled changes over time but also conducted intensive spatial surveys within individual pools and between pools on the same sampling days at individual study sites. Artificial pools had significantly greater DOC concentrations and different spectral absorbance characteristics when compared to natural pools at all sites studied. Within-pool variability in water chemistry tended to be small, even for very large pools ( 400 m2), except where pools had a layer of loose, mobile detritus on their beds. In these instances rapid changes took place between the overlying water column and the mobile sediment layer wherein dissolved oxygen concentrations dropped from values of around 12-10 mg/L to values less than 0.5 mg/L over just 2-3 cm of the depth profile. Such strong contrasts were not observed for pools which had a hard peat floor and which lacked a significant detritus layer. Strong diurnal turnover occurred within the pools on summer days, including within small, shallow pools (e.g. dissolved oxygen concentrations which originated at the surface and was then cycled downwards as the pool surface waters cooled. Slope location was a significant control on several pool water chemistry variables including pH and DOC concentration with accumulation (higher concentrations) in pools that were located further downslope in both natural and artificial pool systems. These processes have important implications for our interpretation of water chemistry and gas flux data from pool systems, how we design our sampling strategies and

  18. Diurnal Variation and Twenty-Four Hour Sleep Deprivation Do Not Alter Supine Heart Rate Variability in Healthy Male Young Adults

    Science.gov (United States)

    Elvsåshagen, Torbjørn; Zak, Nathalia; Norbom, Linn B.; Pedersen, Per Ø.; Quraishi, Sophia H.; Bjørnerud, Atle; Malt, Ulrik F.; Groote, Inge R.; Kaufmann, Tobias; Andreassen, Ole A.; Westlye, Lars T.

    2017-01-01

    Heart rate variability (HRV) has become an increasingly popular index of cardiac autonomic control in the biobehavioral sciences due to its relationship with mental illness and cognitive traits. However, the intraindividual stability of HRV in response to sleep and diurnal disturbances, which are commonly reported in mental illness, and its relationship with executive function are not well understood. Here, in 40 healthy adult males we calculated high frequency HRV—an index of parasympathetic nervous system (PNS) activity—using pulse oximetry during brain imaging, and assessed attentional and executive function performance in a subsequent behavioral test session at three time points: morning, evening, and the following morning. Twenty participants were randomly selected for total sleep deprivation whereas the other 20 participants slept as normal. Sleep deprivation and morning-to-night variation did not influence high frequency HRV at either a group or individual level; however, sleep deprivation abolished the relationship between orienting attention performance and HRV. We conclude that a day of wake and a night of laboratory-induced sleep deprivation do not alter supine high frequency HRV in young healthy male adults. PMID:28151944

  19. Diurnal, weekly, seasonal, and spatial variabilities in carbon dioxide flux in different urban landscapes in Sakai, Japan

    Science.gov (United States)

    Ueyama, Masahito; Ando, Tomoya

    2016-11-01

    To evaluate CO2 emissions in urban areas and their temporal and spatial variability, continuous measurements of CO2 fluxes were conducted using the eddy covariance method at three locations in Sakai, Osaka, Japan. Based on the flux footprint at the measurement sites, CO2 fluxes from the three sites were partitioned into five datasets representing a dense urban center, a moderately urban area, a suburb, an urban park, and a rural area. A distinct biological uptake of CO2 was observed in the suburb, urban park, and rural areas in the daytime, whereas high emissions were observed in the dense and moderate urban areas in the daytime. Weekday CO2 emissions in the dense urban center and suburban area were approximately 50 % greater than emissions during weekends and holidays, but the other landscapes did not exhibit a clear weekly cycle. Seasonal variations in the urban park, rural area, and suburban area were influenced by photosynthetic uptake, exhibiting the lowest daily emissions or even uptake during the summer months. In contrast, the dense and moderately urban areas emitted CO2 in all seasons. CO2 emissions in the urban areas were high in the winter and summer months, and they significantly increased with the increase in air temperature in the summer and the decrease in air temperature in the winter. Irrespective of the land cover type, all urban landscapes measured in this study acted as net annual CO2 sources, with emissions ranging from 0.5 to 4.9 kg C m-2 yr-1. The magnitude of the annual CO2 emissions was negatively correlated with the green fraction; areas with a smaller green fraction had higher annual CO2 emissions. Upscaled flux estimated based on the green fraction indicated that the emissions for the entire city were 3.3 kg C m-2 yr-1, which is equivalent to 0.5 Tg C yr-1 or 1.8 Mt CO2 yr-1, based on the area of the city (149.81 km2). A network of eddy covariance measurements is useful for characterizing the spatial and temporal variations in net CO2

  20. Diurnal internal tides detected in the Adriatic

    Energy Technology Data Exchange (ETDEWEB)

    Mihanovic, H. [Hydrographic Inst. of the Republic of Croatia, Split (Croatia); Orlic, M.; Pasaric, Z. [Andrija Mohorovicic Geophysical Inst., Univ. of Zagreb (Croatia)

    2006-07-01

    Strong diurnal oscillations, documented by temperature data that were collected along a submarine cliff on the Lastovo Island (southern Adriatic), are studied and compared with sea level and wind measurements at Dubrovnik and Komiza (island of Vis). Three thermistors were deployed at the depths of 15, 22 and 36 m between March 2001 and March 2002. Pronounced diurnal temperature oscillations were detected at 15 and 22 m during the stratified season. The correlation between the sea surface and thermocline displacements was highest in June 2001, when diurnal wind changes were not significant, while diurnal sea level oscillations achieved annual maxima. Thermocline oscillations were in phase with sea level changes. The range of diurnal sea surface variability was close to 19 cm, while the range of corresponding thermocline variability was about 5.4 m. The findings summarize the outcome of the first dedicated study of internal tides in the Adriatic. (orig.)

  1. The ALHAMBRA photometric system

    CERN Document Server

    Villegas, T Aparicio; Cabrera-Cano, J; Moles, M; Benitez, N; Perea, J; del Olmo, A; Fernandez-Soto, A; Cristobal-Hornillos, D; Husillos, C; Aguerri, J A L; Broadhurst, T; Castander, F J; Cepa, J; Cervino, M; Delgado, R M Gonzalez; Infante, L; Marquez, I; Masegosa, J; Martinez, V J; Prada, F; Quintana, J M; Sanchez, S F

    2010-01-01

    This paper presents the characterization of the optical range of the ALHAMBRA photometric system, a 20 contiguous, equal-width, medium-band CCD system with wavelength coverage from 3500A to 9700A. The photometric description of the system is done by presenting the full response curve as a product of the filters, CCD and atmospheric transmission curves, and using some first and second order moments of this response function. We also introduce the set of standard stars that defines the system, formed by 31 classic spectrophotometric standard stars which have been used in the calibration of other known photometric systems, and 288 stars, flux calibrated homogeneously, from the Next Generation Spectral Library (NGSL). Based on the NGSL, we determine the transformation equations between Sloan Digital Sky Survey (SDSS) ugriz photometry and the ALHAMBRA photometric system, in order to establish some relations between both systems. Finally we develop and discuss a strategy to calculate the photometric zero points of ...

  2. Diurnal variability of water vapour in the Baltic Sea region according to NCEP-CFSR and BaltAn65+ reanalyses** The survey was supported by the Estonian Science Foundation under a postdoctoral grant JD189, by European Social Fund’s Doctoral Studies and Internationalisation Programme DoRa and project SLOOM12073T, which are carried out by the Archimedes Foundation, and by the Estonian Radiation Climate project, funded by the European Regional Development Fund.

    Directory of Open Access Journals (Sweden)

    Erko Jakobson

    2014-01-01

    Full Text Available Diurnal variations in water vapour in the Baltic Sea region are examined using BaltAn65+ and NCEP-CFSR reanalyses of summer (JJA data for the period 1979–2005. A systematic difference between precipitable water (PW diurnal variability above the land and the water is revealed. Above the land, PW diurnal variability has minimal values at 00 and 06 UTC, as in previous studies, whereas above the water, the minima are at 12 and 18 UTC. Diurnal variability in the vertical humidity profile is controlled by turbulent mixing and the diurnal behaviour of sea breezes. The impacts and proportions of diurnal variability of humidity are evaluated at different vertical levels.

  3. First long-term optical spectro-photometric monitoring of a binary black hole candidate E1821+643: I. Variability of spectral lines and continuum

    CERN Document Server

    Shapovalova, A I; Chavushyan, V H; Burenkov, A N; Ilic, D; Kollatschny, W; Kovacevic, A; Valdes, J R; Patino-Alvarez, V; Leon-Tavares, J; Torrealba, J; Zhdanova, V E

    2016-01-01

    We report the results of the first long-term (1990-2014) optical spectro-photometric monitoring of a binary black hole candidate QSO E1821+643, a low-redshift high-luminosity radio-quiet quasar. In the monitored period the continua and H$\\gamma$ fluxes changed for around two times, while the H$\\beta$ flux changed around 1.4 times. We found the periodical variations in the photometric flux with the periods of 1200, 1850 and 4000 days, and 4500 days periodicity in the spectroscopic variations. However, the periodicity of 4000-4500 days covers only one cycle of variation and should be confirmed with a longer monitoring campaign. There is an indication of the period around 1300 days in the spectroscopic light curves, but with small significance level, while the 1850 days period could not be clearly identified in the spectroscopic light curves. The line profiles have not significantly changed, showing an important red asymmetry and broad line peak redshifted around +1000 km s$^{-1}$. However, H$\\beta$ shows broade...

  4. Diurnal Cycle Computations

    Energy Technology Data Exchange (ETDEWEB)

    Covey, Curt [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Doutriaux, Charles [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-12-01

    Directory /export_backup/covey1/CMIP5/Precipitation/DiurnalCycle/GridpointTimeseries/CMCCBCM_etal/ on crunchy.llnl.gov contains Python / UV-CDAT scripts compositeDiurnalStatistics.py and fourierDiurB nalAllGrid.py. compositeDiurnalStatistics.py reads high-time-frequency climate data from one or more years and computes 24 hour composite-mean and composite-standard-deviation cycles for one requested month.

  5. Seasonal and diurnal variability of essential oil and its components in Origanum onites L. grown in the ecological conditions of Çukurova

    Directory of Open Access Journals (Sweden)

    Kirpik, Muzaffer

    2005-12-01

    Full Text Available Turkish Oregano ( Origanum onites L. is one of the most commonly collected from nature as well as cultivated Origanum species in Turkey . In addition, Turkish Oregano is the most exported Origanum species from Turkey to the entire World. In this study, the seasonal and diurnal variability of the essential oil content in Origanum onites L. grown in the ecological conditions of Çukurova was studied from September 2000-August 2001. Monthly variability of the essential oil composition was also studied. The plant cuttings collected from the region were rooted in the greenhouse and transferred to the field in a split plot design with three replications. One year later from transplanting, fresh leaves from the top shoots were collected every week three times a day on Monday (at 08.00, 12.00 and 16.00 o'clock throughout the year. The content and composition of the essential oil were analysed in fresh leaf samples by hydrodistillation. The essential oil content changed according to the seasons and the hour of day. The highest essential oil content (% 1.92 was found in the post-flowering -at the beginning of the seed formation period in the afternoon harvests during the second half of June (40th week. The essential oil composition varied monthly and the highest value (% 73.65 of carvacrol, the main component of the essential oil, was obtained from the flowering period in MayEl orégano turco ( Origanum onites L. es uno de los más recolectados de la naturaleza así como la especie de orégano más cultivada en Turquía. Además es la especie de orégano más exportada desde Turquía a todo el mundo. En este trabajo se estudió la variabilidad estacional y diurna del contenido de aceite esencial de Origanum onites L. cultivado en las condiciones ecológicas de Çukurova desde Septiembre de 2000 a Agosto de 2001. Se estudió también la variabilidad mensual de la composición del aceite esencial. Los plantones recogidos en la región fueron plantados en un

  6. Uncertain Photometric Redshifts

    CERN Document Server

    Polsterer, Kai Lars; Gieseke, Fabian

    2016-01-01

    Photometric redshifts play an important role as a measure of distance for various cosmological topics. Spectroscopic redshifts are only available for a very limited number of objects but can be used for creating statistical models. A broad variety of photometric catalogues provide uncertain low resolution spectral information for galaxies and quasars that can be used to infer a redshift. Many different techniques have been developed to produce those redshift estimates with increasing precision. Instead of providing a point estimate only, astronomers start to generate probabilistic density functions (PDFs) which should provide a characterisation of the uncertainties of the estimation. In this work we present two simple approaches on how to generate those PDFs. We use the example of generating the photometric redshift PDFs of quasars from SDSS(DR7) to validate our approaches and to compare them with point estimates. We do not aim for presenting a new best performing method, but we choose an intuitive approach t...

  7. Impact of diurnal variability and meteorological factors on the PM2.5 - AOD relationship: Implications for PM2.5 remote sensing.

    Science.gov (United States)

    Guo, Jianping; Xia, Feng; Zhang, Yong; Liu, Huan; Li, Jing; Lou, Mengyun; He, Jing; Yan, Yan; Wang, Fu; Min, Min; Zhai, Panmao

    2017-02-01

    PM2.5 retrieval from space is still challenging due to the elusive relationship between PM2.5 and aerosol optical depth (AOD), which is further complicated by meteorological factors. In this work, we investigated the diurnal cycle of PM2.5 in China, using ground-based PM measurements obtained at 226 sites of China Atmosphere Watch Network during the period of January 2013 to December 2015. Results showed that nearly half of the sites witnessed a PM2.5 maximum in the morning, in contrast to the least frequent occurrence (5%) in the afternoon when strong solar radiation received at the surface results in rapid vertical diffusion of aerosols and thus lower mass concentration. PM2.5 tends to peak equally in the morning and evening in North China Plain (NCP) with an amplitude of nearly twice or three times that in the Pearl River Delta (PRD), whereas the morning PM2.5 peak dominates in Yangtze River Delta (YRD) with a magnitude lying between those of NCP and PRD. The gridded correlation maps reveal varying correlations around each PM2.5 site, depending on the locations and seasons. Concerning the impact of aerosol diurnal variation on the correlation, the averaging schemes of PM2.5 using 3-h, 5-h, and 24-h time windows tend to have larger R biases, compared with the scheme of 1-h time window, indicating diurnal variation of aerosols plays a significant role in the establishment of explicit correlation between PM2.5 and AOD. In addition, high cloud fraction and relative humidity tend to weaken the correlation, regardless of geographical location. Therefore, the impact of meteorology could be one of the most plausible alternatives in explaining the varying R values observed, due to its non-negligible effect on MODIS AOD retrievals. Our findings have implications for PM2.5 remote sensing, as long as the aerosol diurnal cycle, along with meteorology, are explicitly considered in the future.

  8. SUPERFLARES ON SOLAR-TYPE STARS OBSERVED WITH KEPLER II. PHOTOMETRIC VARIABILITY OF SUPERFLARE-GENERATING STARS: A SIGNATURE OF STELLAR ROTATION AND STARSPOTS

    Energy Technology Data Exchange (ETDEWEB)

    Notsu, Yuta; Shibayama, Takuya; Notsu, Shota; Nagao, Takashi [Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); Maehara, Hiroyuki; Honda, Satoshi; Ishii, Takako T.; Nogami, Daisaku; Shibata, Kazunari, E-mail: ynotsu@kwasan.kyoto-u.ac.jp [Kwasan and Hida Observatories, Kyoto University, Kitakazan-ohmine-cho, Yamashina-ku, Kyoto 607-8471 (Japan)

    2013-07-10

    We performed simple spot-model calculations for quasi-periodic brightness variations of solar-type stars showing superflares using Kepler photometric data. Most of the superflare stars show quasi-periodic brightness modulations with a typical period of one to a few tens of days. Our results indicate that these brightness variations can be explained by the rotation of a star with fairly large starspots. Using the results of the period analysis, we investigated the relation between the energy and frequency of superflares and the rotation period. Stars with relatively slower rotation rates can still produce flares that are as energetic as those of more rapidly rotating stars although the average flare frequency is lower for more slowly rotating stars. We found that the energy of superflares is related to the total coverage of the starspot. The correlation between the spot coverage and the flare energy in superflares is similar to that in solar flares. These results suggest that the energy of superflares can be explained by the magnetic energy stored around the starspots.

  9. Sonneberg Sky Patrol Archive - Photometric Analysis

    CERN Document Server

    Spasovic, Milan; Lange, Christian; Jovanovic, Dragan; Schrimpf, Andreas

    2016-01-01

    The Sonneberg Sky Patrol archive so far has not yet been analyzed systematically. In this paper we present first steps towards an automated photometric analysis aiming at the search for variable stars and transient phenomena like novae. Early works on the sky patrol plates showed that photometric accuracy can be enhanced with fitting algorithms. The procedure used was a manually supported click-and-fit-routine, not suitable for automatic analysis of vast amount of photographic plates. We will present our progress on deconvolution of overlapping sources on the plates and compare photometric analysis using different methods. Our goal is to get light curves of sufficient quality from sky patrol plates, which can be classified with machine learning algorithms. The development of an automated scheme for finding transient events is in progress and the first results are very promising.

  10. Spatial and temporal variability of carbon dioxide and methane fluxes over semi-diurnal and spring-neap-spring timescales in a mangrove creek

    Science.gov (United States)

    Call, M.; Maher, D. T.; Santos, I. R.; Ruiz-Halpern, S.; Mangion, P.; Sanders, C. J.; Erler, D. V.; Oakes, J. M.; Rosentreter, J.; Murray, R.; Eyre, B. D.

    2015-02-01

    Automated in situ instrumentation captured high-resolution surface water pCO2, CH4 and 222Rn data at the creek mouth, and ∼500 m upstream in a sub-tropical mangrove ecosystem (Southern Moreton Bay, Australia, S27.78°, E153.38°) over a spring-neap-spring tidal cycle (∼15 days) during November 2013. The partial pressure of CO2 (pCO2) ranged from 385 to 26,106 μatm, CH4 from 1.8 to 889 nM, and 222Rn from 280 to 108,172 dpm m-3. Average surface water pCO2, CH4 and 222Rn were 4-fold higher at the upstream station. Surface water fluxes of CO2 and CH4 ranged from 9.4 to 629.2 mmol CO2 m-2 d-1 and 13.1 to 632.9 μmol CH4 m-2 d-1 depending upon the gas transfer model used and station location. Creek pCO2, CH4 and 222Rn displayed changes over both semi-diurnal and spring-neap-spring tidal scales. Semi-diurnally, all gases had a significant inverse relationship with water depth. Over the spring-neap-spring cycle, all gases exhibited an inverse relationship with tidal amplitude, with higher values during neap tides than spring tides. Estimated fluxes, porewater observations, and the significant positive relationship between surface water pCO2 and CH4, and 222Rn suggests groundwater exchange (i.e., tidal pumping) drives pCO2 and CH4 within the mangrove creek. We hypothesize that a combination of hourly and weekly groundwater-surface water exchange processes drive surface water pCO2 and CH4 in mangrove creeks. Semi-diurnally, flushing of crab burrows leads to high pCO2 and CH4 concentrations at low tide. During the spring-neap-spring cycle, older groundwater enriched in CO2, CH4 and 222Rn seeps into the creek as tidal amplitude decreases, leading to higher concentrations at neap tides.

  11. Improved boundary layer height measurement using a fuzzy logic method: Diurnal and seasonal variabilities of the convective boundary layer over a tropical station

    Science.gov (United States)

    Allabakash, S.; Yasodha, P.; Bianco, L.; Venkatramana Reddy, S.; Srinivasulu, P.; Lim, S.

    2017-09-01

    This paper presents the efficacy of a "tuned" fuzzy logic method at determining the height of the boundary layer using the measurements from a 1280 MHz lower atmospheric radar wind profiler located in Gadanki (13.5°N, 79°E, 375 mean sea level), India, and discusses the diurnal and seasonal variations of the measured convective boundary layer over this tropical station. The original fuzzy logic (FL) method estimates the height of the atmospheric boundary layer combining the information from the range-corrected signal-to-noise ratio, the Doppler spectral width of the vertical velocity, and the vertical velocity itself, measured by the radar, through a series of thresholds and rules, which did not prove to be optimal for our radar system and geographical location. For this reason the algorithm was tuned to perform better on our data set. Atmospheric boundary layer heights obtained by this tuned FL method, the original FL method, and by a "standard method" (that only uses the information from the range-corrected signal-to-noise ratio) are compared with those obtained from potential temperature profiles measured by collocated Global Positioning System Radio Sonde during years 2011 and 2013. The comparison shows that the tuned FL method is more accurate than the other methods. Maximum convective boundary layer heights are observed between 14:00 and 15:00 local time (LT = UTC + 5:30) for clear-sky days. These daily maxima are found to be lower during winter and postmonsoon seasons and higher during premonsoon and monsoon seasons, due to net surface radiation and convective processes over this region being more intense during premonsoon and monsoon seasons and less intense in winter and postmonsoon seasons.

  12. Seasonal, synoptic, and diurnal-scale variability of biogeochemical trace gases and O2 from a 300-m tall tower in central Siberia

    Science.gov (United States)

    Kozlova, Elena A.; Manning, Andrew C.; Kisilyakhov, Yegor; Seifert, Thomas; Heimann, Martin

    2008-12-01

    We present first results from 19 months of semicontinuous concentration measurements of biogeochemical trace gases (CO2, CO, and CH4) and O2, measured at the Zotino Tall Tower Observatory (ZOTTO) in the boreal forest of central Siberia. We estimated CO2 and O2 seasonal cycle amplitudes of 26.6 ppm and 134 per meg, respectively. An observed west-east gradient of about -7 ppm (in July 2006) between Shetland Islands, Scotland, and ZOTTO reflects summertime continental uptake of CO2 and is consistent with regional modeling studies. We found the oceanic component of the O2 seasonal amplitude (Atmospheric Potential Oxygen, or APO) to be 51 per meg, significantly smaller than the 95 per meg observed at Shetlands, illustrating a strong attenuation of the oceanic O2 signal in the continental interior. Comparison with the Tracer Model 3 (TM3) atmospheric transport model showed good agreement with the observed phasing and seasonal amplitude in CO2; however, the model exhibited greater O2 (43 per meg, 32%) and smaller APO (9 per meg, 18%) amplitudes. This seeming inconsistency in model comparisons between O2 and APO appears to be the result of phasing differences in land and ocean signals observed at ZOTTO, where ocean signals have a significant lag. In the first 2 months of measurements on the fully constructed tower (November and December 2006), we observed several events with clear vertical concentration gradients in all measured species except CO. During "cold events" (below -30°C) in November 2006, we observed large vertical gradients in CO2 (up to 22 ppm), suggesting a strong local source. The same pattern was observed in CH4 concentrations for the same events. Diurnal vertical CO2 gradients in April to May 2007 gave estimates for average nighttime respiration fluxes of 0.04 ± 0.02 mol C m-2 d-1, consistent with earlier eddy covariance measurements in 1999-2000 in the vicinity of the tower.

  13. Seasonal pH variability in the Saronikos Gulf: A year-study using a new photometric pH sensor

    Science.gov (United States)

    González-Dávila, Melchor; Santana-Casiano, J. Magdalena; Petihakis, George; Ntoumas, Manolis; Suárez de Tangil, Miguel; Krasakopoulou, Evangelia

    2016-10-01

    Long-term determination of carbon dioxide data is a priority requirement to ensure a realistic picture of how ocean seawater properties change as the result of atmospheric evolution. Due to the extreme daily and seasonal variability of the carbonate system characteristics, constant autonomous measurements are a necessity when seeking to provide total spatial-temporal coverage of inorganic carbon data. We present here results of a one-year study in the Eastern Mediterranean Aegean Sea by using a new spectrophotometric pH-based system, applicable in long time deployments. The manifold has proved to be capable of providing sea-surface temperature and salinity together with highly accurate pH values determined each 6 h over the period between September 2013 and October 2014. The average seasonal temperature difference of 12.4 °C, determined from March to September, can be correlated to the seasonal pH decrease of 0.2 pH units, from 8.18 to 7.98. The area also presented a maximum seasonal change in partial pressure of CO2 of 208 μatm, computed from the salinity-based total alkalinity values. The Saronikos area in the Aegean Sea was characterized to be a thermodynamically controlled region, since it is oligotrophic, acting as a source of CO2 into the atmosphere of 0.20 mol m- 2 yr- 1.

  14. The role of meltwater variability in modulating diurnal to inter-annual ice-sheet flow: New insights from a ~decade of high-temporal resolution GPS observations on the western Greenland margin

    Science.gov (United States)

    Stevens, L. A.; Behn, M. D.; Das, S. B.; Joughin, I.; van den Broeke, M.; Herring, T.; McGuire, J. J.

    2015-12-01

    Meltwater-driven processes across the ablation zone of the Greenland Ice Sheet are controlled by seasonal fluxes as well as shorter-term variability in surface melt. Few high-temporal resolution GPS observations of ice-sheet flow extend for longer than a couple years, limiting multiyear analyses of seasonal variability in ice-sheet flow. Using a small GPS network installed at ~1000-m above sea level (m a.s.l.) operating from 2006-2014, and supplemented with a larger array of 20 GPS stations installed from 2011­-2014, we observe nine years of ice-sheet surface motion on the western margin of the Greenland Ice Sheet. The GPS array spans a horizontal distance of 30 km across an elevation range of 700-1250 m a.s.l., and captures the ice-sheet's velocity response to the seasonal melt cycle. By combining the GPS array measurements with temperature, precipitation, and runoff estimates from the Regional Atmospheric Climate Model (RACMO), we examine the relationship between ice-sheet flow and surface melt variability both at the seasonal scale (i.e., during melt onset, summer melt season and melt cessation) as well as during transient high melt periods such as precipitation events, anomalously high melt episodes, and supraglacial lake drainages. We observe varying surface motion following early versus late summer extended melt events, with early-season extended melt events inducing longer sustained speed-up than late summer events. We also examine differences in the timing of melt onset and magnitude, comparing the anomalously high runoff observed across the ice sheet in 2010 and 2012 against the average to low runoff observed in the years comprising the remainder of the record. This nearly decadal record improves our understanding of the role of meltwater variability in modulating ice-sheet flow on diurnal to inter-annual timescales.

  15. A preliminary study on the relationships between diurnal melatonin secretion profile and sleep variables in patients emergently admitted to the coronary care unit.

    Science.gov (United States)

    Takaesu, Yoshikazu; Futenma, Kunihiro; Kobayashi, Mina; Komada, Yoko; Tanaka, Nobuhiro; Yamashina, Akira; Inoue, Yuichi

    2015-01-01

    To clarify the significance of melatonin secretion under intensive care conditions, we investigated melatonin secretion profiles and sleep parameters of 23 patients just after admission to the coronary care unit (CCU) and 19 age-matched controls. Sleep parameters were evaluated by actigraphy, and melatonin secretion was assessed by measuring the urinary 6-sulphatoxy melatonin (6-SMT). 6-SMT secretion was lower and nocturnal sleep parameters were less satisfactory in the subjects than those in the controls, and there were positive correlations between these variables, particularly in the subject patients. The lowered melatonin secretion might be involved in the mechanism of insomnia in CCU patients.

  16. Photometric determinants of perceived transparency.

    Science.gov (United States)

    Singh, Manish; Anderson, Barton L

    2006-03-01

    Photometric constraints for the perception of transparency were investigated using stereoscopic textured displays. A contrast discontinuity divided the textured displays into two lateral halves, with one (reference) half fixed. Observers adjusted the luminance range within the other (test) half in order to perform two tasks: (i) indicate the highest luminance range for which the test side is perceived to be transparent, and (ii) indicate the lowest luminance range for which the test side is seen as being in plain view. Settings were obtained for multiple values of test mean luminance, in order to map out the perceptual locus of transition between transparency and non-transparency. The results revealed a systematic violation of Metelli's magnitude constraint in predicting the percept of transparency. Observer settings were approximated instead by a constraint based on perceived contrast (which matched Michelson contrast for the textures used). The results also revealed large asymmetries between darkening and lightening transparency. When the test was darker than the reference, settings were highly consistent across observers and closely followed the Michelson-contrast prediction. When the test was lighter, however, there was greater variability across observers, with two observers exhibiting shifts toward Metelli's magnitude constraint. Moreover, each observer's setting reliability was significantly worse for lightening transparency than darkening transparency. These results suggest that (polarity-preserving) darkening serves as an additional cue to perceptual transparency.

  17. Na lidar Investigation of gravity wave forcing and its effects on tidal variability in mesopause region by nocturnal zonal momentum flux measurement and full-diurnal cycle lidar observations at Logan, UT (42N, 118W)

    Science.gov (United States)

    Yuan, T.; Zhao, Y.; Pautet, P.; Cai, X.; Fish, C. S.; Taylor, M. J.

    2012-12-01

    Gravity wave forcing (GWF) is induced by the momentum deposition during the wave breaking event. It is believed to be the major dynamic source in the mesosphere and lower thermosphere (MLT) that affects not only the global climatological features but also the mesoscale events in this region. The Utah State University (USU) Na Doppler Temperature/Wind lidar set up zonal co-planner beam in June 2011 to measure the zonal momentum flux through zonal wind variance calculations. Meanwhile, the lidar's multi-day continuous full diurnal cycle observations provide opportunity to investigate the GWF on the tidal wave variability and propagations within the mesopause region. In this paper, we are going to discuss the nocturnal GWF revealed by the lidar momentum flux measurements in one collaborative continuous 5-day campaign with Advance Mesospheric Temperature Mapper (AMTM) at USU and the Meteor Wind Radar at Bear Lake Observatory (BLO) in August 2011. The AMTM also captured one intensive mesospheric "Bore" event during one night with strong GWF, while TIMED/SABER data indicates that the temperature inversion layer (thermal duct region for "Bore" propagation) is well over 1000 km in horizontal scale, extending beyond west coast of North America. The correlation between zonal GWF and tidal wave will be investigated, along with planetary wave behavior through this campaign.

  18. Calibration of the MEarth Photometric System: Optical Magnitudes and Photometric Metallicity Estimates for 1802 Nearby M-dwarfs

    CERN Document Server

    Dittmann, Jason A; Charbonneau, David; Newton, Elisabeth R

    2015-01-01

    The MEarth Project is a photometric survey systematically searching the smallest stars nearest to the Sun for transiting rocky planets. Since 2008, MEarth has taken approximately two million images of 1844 stars suspected to be mid-to-late M dwarfs. We have augmented this survey by taking nightly exposures of photometric standard stars and have utilized this data to photometrically calibrate the $MEarth$ system, identify photometric nights, and obtain an optical magnitude with $1.5\\%$ precision for each M dwarf system. Each optical magnitude is an average over many years of data, and therefore should be largely immune to stellar variability and flaring. We combine this with trigonometric distance measurements, spectroscopic metallicity measurements, and 2MASS infrared magnitude measurements in order to derive a color-magnitude-metallicity relation across the mid-to-late M dwarf spectral sequence that can reproduce spectroscopic metallicity determinations to a precision of 0.1 dex. We release optical magnitude...

  19. Photometric stereo endoscopy

    Science.gov (United States)

    Parot, Vicente; Lim, Daryl; González, Germán; Traverso, Giovanni; Nishioka, Norman S.; Vakoc, Benjamin J.

    2013-01-01

    Abstract. While color video endoscopy has enabled wide-field examination of the gastrointestinal tract, it often misses or incorrectly classifies lesions. Many of these missed lesions exhibit characteristic three-dimensional surface topographies. An endoscopic system that adds topographical measurements to conventional color imagery could therefore increase lesion detection and improve classification accuracy. We introduce photometric stereo endoscopy (PSE), a technique which allows high spatial frequency components of surface topography to be acquired simultaneously with conventional two-dimensional color imagery. We implement this technique in an endoscopic form factor and demonstrate that it can acquire the topography of small features with complex geometries and heterogeneous optical properties. PSE imaging of ex vivo human gastrointestinal tissue shows that surface topography measurements enable differentiation of abnormal shapes from surrounding normal tissue. Together, these results confirm that the topographical measurements can be obtained with relatively simple hardware in an endoscopic form factor, and suggest the potential of PSE to improve lesion detection and classification in gastrointestinal imaging. PMID:23864015

  20. Photometric redshifts for the NGVS

    Science.gov (United States)

    Raichoor, A.; Mei, S.; Erben, T.; Hildebrandt, H.; Huertas-Company, M.; Ilbert, O.; Licitra, R.; Ball, N. M.; Boissier, S.; Boselli, A.; Chen, Y.-T.; Côté, P.; Cuillandre, J.-C.; Duc, P. A.; Durrell, P. R.; Ferrarese, L.; Guhathakurta, P.; Gwyn, S. D. J.; Kavelaars, J. J.; Lancon, A.; Liu, C.; MacArthur, L. A.; Muller, M.; Muñoz, R. P.; Peng, E. W.; Puzia, T. H.; Sawicki, M.; Toloba, E.; Van Waerbeke, L.; Woods, D.; Zhang, H.

    2014-12-01

    We present the photometric redshift catalog for the Next Generation Virgo Cluster Survey (NGVS), a 104 deg^2 optical imaging survey centered on the Virgo cluster in the u^*, g, r ,i, z bandpasses at point source depth of 25-26 ABmag. It already is the new optical reference survey for the study of the Virgo cluster, and will be also used for multiple ancillary programs. To obtain photometric redshifts, we perform accurate photometry, through the PSF-homogenization of our data. We then estimate the photometric redshifts using Le Phare and BPZ codes, adding a new prior extended down to i_{AB}=12.5 mag. We assess the accuracy of our photometric redshifts as a function of magnitude and redshift using ˜80,000 spectroscopic redshifts from public surveys. For i_{AB} outliers.

  1. Evaluating the diurnal cycle in cloud top temperature from SEVIRI

    Directory of Open Access Journals (Sweden)

    S. Taylor

    2017-06-01

    Full Text Available The variability of convective cloud spans a wide range of temporal and spatial scales and is of fundamental importance for global weather and climate systems. Datasets from geostationary satellite instruments such as the Spinning Enhanced Visible and Infrared Imager (SEVIRI provide high-time-resolution observations across a large area. In this study we use data from SEVIRI to quantify the diurnal cycle of cloud top temperature within the instrument's field of view and discuss these results in relation to retrieval biases. We evaluate SEVIRI cloud top temperatures from the new CLAAS-2 (CLoud property dAtAset using SEVIRI, Edition 2 dataset against Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP data. Results show a mean bias of +0.44 K with a standard deviation of 11.7 K, which is in agreement with previous validation studies. Analysis of the spatio-temporal distribution of these errors shows that absolute retrieval biases vary from less than 5 K over the southeast Atlantic Ocean up to 30 K over central Africa at night. Night- and daytime retrieval biases can also differ by up to 30 K in some areas, potentially contributing to biases in the estimated amplitude of the diurnal cycle. This illustrates the importance of considering spatial and diurnal variations in retrieval errors when using the CLAAS-2 dataset. Keeping these biases in mind, we quantify the seasonal, diurnal, and spatial variation of cloud top temperature across SEVIRI's field of view using the CLAAS-2 dataset. By comparing the mean diurnal cycle of cloud top temperature with the retrieval bias, we find that diurnal variations in the retrieval bias can be small but are often of the same order of magnitude as the amplitude of the observed diurnal cycle, indicating that in some regions the diurnal cycle apparent in the observations may be significantly impacted by diurnal variability in the accuracy of the retrieval. We show that the CLAAS-2 dataset can measure the

  2. Evaluating the diurnal cycle in cloud top temperature from SEVIRI

    Science.gov (United States)

    Taylor, Sarah; Stier, Philip; White, Bethan; Finkensieper, Stephan; Stengel, Martin

    2017-06-01

    The variability of convective cloud spans a wide range of temporal and spatial scales and is of fundamental importance for global weather and climate systems. Datasets from geostationary satellite instruments such as the Spinning Enhanced Visible and Infrared Imager (SEVIRI) provide high-time-resolution observations across a large area. In this study we use data from SEVIRI to quantify the diurnal cycle of cloud top temperature within the instrument's field of view and discuss these results in relation to retrieval biases. We evaluate SEVIRI cloud top temperatures from the new CLAAS-2 (CLoud property dAtAset using SEVIRI, Edition 2) dataset against Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) data. Results show a mean bias of +0.44 K with a standard deviation of 11.7 K, which is in agreement with previous validation studies. Analysis of the spatio-temporal distribution of these errors shows that absolute retrieval biases vary from less than 5 K over the southeast Atlantic Ocean up to 30 K over central Africa at night. Night- and daytime retrieval biases can also differ by up to 30 K in some areas, potentially contributing to biases in the estimated amplitude of the diurnal cycle. This illustrates the importance of considering spatial and diurnal variations in retrieval errors when using the CLAAS-2 dataset. Keeping these biases in mind, we quantify the seasonal, diurnal, and spatial variation of cloud top temperature across SEVIRI's field of view using the CLAAS-2 dataset. By comparing the mean diurnal cycle of cloud top temperature with the retrieval bias, we find that diurnal variations in the retrieval bias can be small but are often of the same order of magnitude as the amplitude of the observed diurnal cycle, indicating that in some regions the diurnal cycle apparent in the observations may be significantly impacted by diurnal variability in the accuracy of the retrieval. We show that the CLAAS-2 dataset can measure the diurnal cycle of cloud tops

  3. Upscaling diurnal cycles of carbon fluxes

    Science.gov (United States)

    Bodesheim, Paul; Jung, Martin; Mahecha, Miguel; Reichstein, Markus

    2017-04-01

    Carbon fluxes like Gross Primary Production (GPP) and Net Ecosystem Exchange (NEE) are important variables for studying interactions between the atmosphere and the biosphere in different ecosystems. They are typically derived from measurements at Eddy covariance towers and the FLUXNET global network consists of hundreds of such sites. In order to diagnose global GPP and NEE patterns from FLUXNET, upscaling approaches have been used in the past to extrapolate the site measurements to continental and global scale. However, respective products have a daily or monthly temporal resolution and do not allow for analyzing patterns related to diurnal variations of GPP and NEE. To raise these upscaling approaches to the next level, we present our first results on upscaling diurnal cycles of GPP and NEE with half-hourly resolution. We use random forest regression models to estimate the relationship between predictor variables and fluxes based on more than four million half-hourly observations from FLUXNET sites. We have developed and tested two approaches that overcome the mismatch in the temporal resolution between predictor variables at daily resolution and fluxes at half-hourly resolution. Based on thorough leave-one-site-out cross-validation we show that the approach works very well. Finally, we used the trained models for computing global products of half-hourly GPP and NEE that cover the years 2001 to 2014 and present global patterns of diurnal carbon flux variations derived from the upscaling approach.

  4. Probabilistic Photometric Redshifts in the Era of Petascale Astronomy

    Energy Technology Data Exchange (ETDEWEB)

    Carrasco Kind, Matias [Univ. of Illinois, Urbana-Champaign, IL (United States)

    2014-01-01

    With the growth of large photometric surveys, accurately estimating photometric redshifts, preferably as a probability density function (PDF), and fully understanding the implicit systematic uncertainties in this process has become increasingly important. These surveys are expected to obtain images of billions of distinct galaxies. As a result, storing and analyzing all of these photometric redshift PDFs will be non-trivial, and this challenge becomes even more severe if a survey plans to compute and store multiple different PDFs. In this thesis, we have developed an end-to-end framework that will compute accurate and robust photometric redshift PDFs for massive data sets by using two new, state-of-the-art machine learning techniques that are based on a random forest and a random atlas, respectively. By using data from several photometric surveys, we demonstrate the applicability of these new techniques, and we demonstrate that our new approach is among the best techniques currently available. We also show how different techniques can be combined by using novel Bayesian techniques to improve the photometric redshift precision to unprecedented levels while also presenting new approaches to better identify outliers. In addition, our framework provides supplementary information regarding the data being analyzed, including unbiased estimates of the accuracy of the technique without resorting to a validation data set, identification of poor photometric redshift areas within the parameter space occupied by the spectroscopic training data, and a quantification of the relative importance of the variables used during the estimation process. Furthermore, we present a new approach to represent and store photometric redshift PDFs by using a sparse representation with outstanding compression and reconstruction capabilities. We also demonstrate how this framework can also be directly incorporated into cosmological analyses. The new techniques presented in this thesis are crucial

  5. Calibrating Photometric Redshifts of Luminous Red Galaxies

    CERN Document Server

    Padmanabhan, N; Schlegel, D J; Bridges, T J; Brinkmann, J; Cannon, R; Connolly, A J; Croom, S M; Csabai, I; Drinkwater, M; Eisenstein, D J; Hewett, P C; Loveday, J; Nichol, R C; Pimbblet, K A; De Propris, R; Schneider, D P; Scranton, R; Seljak, U; Shanks, T; Szapudi, I; Szalay, A S; Wake, D; Padmanabhan, Nikhil; Budavari, Tamas; Schlegel, David J.; Bridges, Terry; Brinkmann, Jonathan; Cannon, Russell; Connolly, Andrew J.; Croom, Scott M.; Csabai, Istvan; Drinkwater, Michael; Eisenstein, Daniel J.; Hewett, Paul C.; Loveday, Jon; Nichol, Robert C.; Pimbblet, Kevin A.; Propris, Roberto De; Schneider, Donald P.; Scranton, Ryan; Seljak, Uros; Shanks, Tom; Szapudi, Istvan; Szalay, Alexander S.; Wake, David

    2004-01-01

    We discuss the construction of a photometric redshift catalogue of Luminous Red Galaxies (LRGs) from the Sloan Digital Sky Survey (SDSS), emphasizing the principal steps necessary for constructing such a catalogue -- (i) photometrically selecting the sample, (ii) measuring photometric redshifts and their error distributions, (iii) and estimating the true redshift distribution. We compare two photometric redshift algorithms for these data and find that they give comparable results. Calibrating against the SDSS and SDSS-2dF spectroscopic surveys, we find that the photometric redshift accuracy is $\\sigma \\sim 0.03$ for redshifts less than 0.55 and worsens at higher redshift ($\\sim 0.06$). These errors are caused by photometric scatter, as well as systematic errors in the templates, filter curves, and photometric zeropoints. We also parametrize the photometric redshift error distribution with a sum of Gaussians, and use this model to deconvolve the errors from the measured photometric redshift distribution to est...

  6. Photometric Study of Selected Asteroids

    Science.gov (United States)

    Shevchenko, Vasilij G.; Velichko, Feodor P.; Checha, Vitaly A.; Krugly, Yurij N.

    2014-07-01

    We performed photometric observations for eleven asteroids. New rotation periods were determined for five asteroids: 2812 Scaltriti (7.596 h), 4716 Urey (6.2 h), 7446 Hadrianus (3.402 h), (26657) 2000 SX293 (2.8 - 3.8 h), and (54063) 2000 GC136 (5.154 h).

  7. Diurnal Ensemble Surface Meteorology Statistics

    Data.gov (United States)

    U.S. Environmental Protection Agency — Excel file containing diurnal ensemble statistics of 2-m temperature, 2-m mixing ratio and 10-m wind speed. This Excel file contains figures for Figure 2 in the...

  8. The diurnal cycle of clouds and precipitation : an evaluation of multiple data sources

    OpenAIRE

    Pfeifroth, Uwe Anton

    2016-01-01

    Clouds and precipitation are essential climate variables. Because of their high spatial and temporal variability, their observation and modeling is difficult. In this thesis multiple observational data sources, including satellite data and station data are globally analyzed to understand the distribution and variability of clouds and precipitation, while a special focus is on the diurnal cycle of both variables. Substantial diurnal cycles of clouds and precipitation are observed in the tropic...

  9. Planck 2013 results. VIII. HFI photometric calibration and mapmaking

    CERN Document Server

    Ade, P A R; Armitage-Caplan, C; Arnaud, M; Ashdown, M; Atrio-Barandela, F; Aumont, J; Baccigalupi, C; Banday, A J; Barreiro, R B; Battaner, E; Benabed, K; Benoît, A; Benoit-Lévy, A; Bernard, J -P; Bersanelli, M; Bertincourt, B; Bielewicz, P; Bobin, J; Bock, J J; Bond, J R; Borrill, J; Bouchet, F R; Boulanger, F; Bridges, M; Bucher, M; Burigana, C; Cardoso, J -F; Catalano, A; Challinor, A; Chamballu, A; Chary, R -R; Chen, X; Chiang, L -Y; Chiang, H C; Christensen, P R; Church, S; Clements, D L; Colombi, S; Colombo, L P L; Combet, C; Couchot, F; Coulais, A; Crill, B P; Curto, A; Cuttaia, F; Danese, L; Davies, R D; de Bernardis, P; de Rosa, A; de Zotti, G; Delabrouille, J; Delouis, J -M; Désert, F -X; Dickinson, C; Diego, J M; Dole, H; Donzelli, S; Doré, O; Douspis, M; Dupac, X; Efstathiou, G; Enßlin, T A; Eriksen, H K; Filliard, C; Finelli, F; Forni, O; Frailis, M; Franceschi, E; Galeotta, S; Ganga, K; Giard, M; Giardino, G; Giraud-Héraud, Y; González-Nuevo, J; Górski, K M; Gratton, S; Gregorio, A; Gruppuso, A; Hansen, F K; Hanson, D; Harrison, D; Helou, G; Henrot-Versillé, S; Hernández-Monteagudo, C; Herranz, D; Hildebrandt, S R; Hivon, E; Hobson, M; Holmes, W A; Hornstrup, A; Hovest, W; Huffenberger, K M; Jaffe, T R; Jaffe, A H; Jones, W C; Juvela, M; Keihänen, E; Keskitalo, R; Kisner, T S; Kneissl, R; Knoche, J; Knox, L; Kunz, M; Kurki-Suonio, H; Lagache, G; Lamarre, J -M; Lasenby, A; Laureijs, R J; Lawrence, C R; Jeune, M Le; Lellouch, E; Leonardi, R; Leroy, C; Lesgourgues, J; Liguori, M; Lilje, P B; Linden-Vørnle, M; López-Caniego, M; Lubin, P M; Macías-Pérez, J F; Maffei, B; Mandolesi, N; Maris, M; Marshall, D J; Martin, P G; Martínez-González, E; Masi, S; Matarrese, S; Matthai, F; Maurin, L; Mazzotta, P; McGehee, P; Meinhold, P R; Melchiorri, A; Mendes, L; Mennella, A; Migliaccio, M; Mitra, S; Miville-Deschênes, M -A; Moneti, A; Montier, L; Moreno, R; Morgante, G; Mortlock, D; Munshi, D; Murphy, J A; Naselsky, P; Nati, F; Natoli, P; Netterfield, C B; Nørgaard-Nielsen, H U; Noviello, F; Novikov, D; Novikov, I; Osborne, S; Oxborrow, C A; Paci, F; Pagano, L; Pajot, F; Paladini, R; Paoletti, D; Partridge, B; Pasian, F; Patanchon, G; Perdereau, O; Perotto, L; Perrotta, F; Piacentini, F; Piat, M; Pierpaoli, E; Pietrobon, D; Plaszczynski, S; Pointecouteau, E; Polenta, G; Ponthieu, N; Popa, L; Poutanen, T; Pratt, G W; Prézeau, G; Prunet, S; Puget, J -L; Rachen, J P; Reinecke, M; Remazeilles, M; Renault, C; Ricciardi, S; Riller, T; Ristorcelli, I; Rocha, G; Rosset, C; Roudier, G; Rusholme, B; Santos, D; Savini, G; Shellard, E P S; Spencer, L D; Starck, J -L; Stolyarov, V; Stompor, R; Sudiwala, R; Sunyaev, R; Sureau, F; Sutton, D; Suur-Uski, A -S; Sygnet, J -F; Tauber, J A; Tavagnacco, D; Techene, S; Terenzi, L; Tomasi, M; Tristram, M; Tucci, M; Umana, G; Valenziano, L; Valiviita, J; Van Tent, B; Vielva, P; Villa, F; Vittorio, N; Wade, L A; Wandelt, B D; Yvon, D; Zacchei, A; Zonca, A

    2014-01-01

    This paper describes the processing applied to the HFI cleaned time-ordered data to produce photometrically calibrated maps. HFI observes the sky over a broad range of frequencies, from 100 to 857 GHz. To get the best accuracy on the calibration on such a large range, two different photometric calibration schemes have to be used. The 545 and 857 \\GHz\\ data are calibrated using Uranus and Neptune flux density measurements, compared with models of their atmospheric emissions to calibrate the data. The lower frequencies (below 353 GHz) are calibrated using the cosmological microwave background dipole.One of the components of this anisotropy results from the orbital motion of the satellite in the Solar System, and is therefore time-variable. Photometric calibration is thus tightly linked to mapmaking, which also addresses low frequency noise removal. The 2013 released HFI data show some evidence for apparent gain variations of the HFI bolometers' detection chain. These variations were identified by comparing obse...

  10. Diurnal variation of mountain waves

    Directory of Open Access Journals (Sweden)

    R. M. Worthington

    2006-11-01

    Full Text Available Mountain waves could be modified as the boundary layer varies between stable and convective. However case studies show mountain waves day and night, and above e.g. convective rolls with precipitation lines over mountains. VHF radar measurements of vertical wind (1990–2006 confirm a seasonal variation of mountain-wave amplitude, yet there is little diurnal variation of amplitude. Mountain-wave azimuth shows possible diurnal variation compared to wind rotation across the boundary layer.

  11. A Photometric Study of Stars in the MBM 12 Association

    Science.gov (United States)

    Herbst, William; Williams, Eric C.; Hawley, Wendy P.

    2004-03-01

    We have monitored four fields containing nine previously identified members of the MBM 12 association to search for photometric variability and periodicity in these pre-main-sequence stars. Seven of the nine are found to be variable and definite periodicity (of 1.2, 2.6, and 6.2 days) is found for three of them, including the classical T Tauri star LkHα 264. Two other members are possibly periodic, but each requires confirmation. In addition, a ``field'' star that is associated with the X-ray source RX J0255.9+2005 was discovered to be a variable with a period of 4.2 days. Our results indicate that the photometric variability characteristics of the known MBM 12 association members are typical of what is found in roughly few-million-year-old stellar groups such as IC 348, supporting arguments for a similar age. In particular, there is a mix of periodic and nonperiodic variables with typical amplitudes (in Cousins I) of 0.1-0.5 mag, in addition to a small number of larger amplitude variables. The periods, as a group, are somewhat shorter than in IC 348, but when allowance is made for the known dependence of period on mass in pre-main-sequence stars the difference may not be significant. Our data confirm and illustrate the value of photometric monitoring as a tool for identifying likely association members and for studying rotation in extremely young stellar groups.

  12. Impact of resolving the diurnal cycle in an ocean-atmosphere GCM. Pt. 2. A diurnally coupled CGCM

    Energy Technology Data Exchange (ETDEWEB)

    Bernie, D.J. [Met Office Hadley Centre, Exeter (United Kingdom); University of Reading, National Centre for Atmospheric Science-Climate, Department of Meteorology, Reading (United Kingdom); Numeriques, IPSL, Laboratoire d' Oceanographie et du Climat, Experimentation et Approches, Paris (France); Guilyardi, E. [University of Reading, National Centre for Atmospheric Science-Climate, Department of Meteorology, Reading (United Kingdom); Numeriques, IPSL, Laboratoire d' Oceanographie et du Climat, Experimentation et Approches, Paris (France); Madec, G. [Numeriques, IPSL, Laboratoire d' Oceanographie et du Climat, Experimentation et Approches, Paris (France); Slingo, J.M.; Woolnough, S.J.; Cole, J. [University of Reading, National Centre for Atmospheric Science-Climate, Department of Meteorology, Reading (United Kingdom)

    2008-12-15

    Coupled ocean atmosphere general circulation models (GCM) are typically coupled once every 24 h, excluding the diurnal cycle from the upper ocean. Previous studies attempting to examine the role of the diurnal cycle of the upper ocean and particularly of diurnal SST variability have used models unable to resolve the processes of interest. In part 1 of this study a high vertical resolution ocean GCM configuration with modified physics was developed that could resolve the diurnal cycle in the upper ocean. In this study it is coupled every 3 h to atmospheric GCM to examine the sensitivity of the mean climate simulation and aspects of its variability to the inclusion of diurnal ocean-atmosphere coupling. The inclusion of the diurnal cycle leads to a tropics wide increase in mean sea surface temperature (SST), with the strongest signal being across the equatorial Pacific where the warming increases from 0.2 C in the central and western Pacific to over 0.3 C in the eastern equatorial Pacific. Much of this warming is shown to be a direct consequence of the rectification of daily mean SST by the diurnal variability of SST. The warming of the equatorial Pacific leads to a redistribution of precipitation from the Inter tropical convergence zone (ITCZ) toward the equator. In the western Pacific there is an increase in precipitation between Papa new guinea and 170 E of up to 1.2 mm/day, improving the simulation compared to climatology. Pacific sub tropical cells are increased in strength by about 10%, in line with results of part 1 of this study, due to the modification of the exchange of momentum between the equatorially divergent Ekman currents and the geostropic convergence at depth, effectively increasing the dynamical response of the tropical Pacific to zonal wind stresses. During the spring relaxation of the Pacific trade winds, a large diurnal cycle of SST increases the seasonal warming of the equatorial Pacific. When the trade winds then re-intensify, the increase in

  13. Photometric study of IC 2156

    CERN Document Server

    Tadross, A L

    2015-01-01

    The optical UBVRI photometric analysis has been established using SLOAN DIGITAL SKY SURVEY (SDSS database) in order to estimate the astrophysical parameters of poorly studied open star cluster IC 2156. The results of the present study are compared with a previous one of ours, which relied on the 2MASS JHK infrared photometry. The stellar density distributions and color-magnitude diagrams of the cluster are used to determine the geometrical structure; limited radius, core and tidal radii, the distances from the Sun, from the Galactic plane and from the Galactic center. Also, the main photometric parameters; age, distance modulus, color excesses, membership, total mass, luminosity, mass functions and relaxation time; have been estimated.

  14. Overconfidence in Photometric Redshift Estimation

    CERN Document Server

    Wittman, David; Tobin, Ryan

    2016-01-01

    We describe a new test of photometric redshift performance given a spectroscopic redshift sample. This test complements the traditional comparison of redshift {\\it differences} by testing whether the probability density functions $p(z)$ have the correct {\\it width}. We test two photometric redshift codes, BPZ and EAZY, on each of two data sets and find that BPZ is consistently overconfident (the $p(z)$ are too narrow) while EAZY produces approximately the correct level of confidence. We show that this is because EAZY models the uncertainty in its spectral energy distribution templates, and that post-hoc smoothing of the BPZ $p(z)$ provides a reasonable substitute for detailed modeling of template uncertainties. Either remedy still leaves a small surplus of galaxies with spectroscopic redshift very far from the peaks. Thus, better modeling of low-probability tails will be needed for high-precision work such as dark energy constraints with the Large Synoptic Survey Telescope and other large surveys.

  15. Photometric CCD observations of four Pre-cataclysmic binary candidates

    Science.gov (United States)

    Hinojosa, R.; Vogt, N.; Colque, Juan Pablo

    We present preliminary results of differential photometric observations of Abell 65, HZ 9, GD 1401 and BPM 46460, obtained between September and December 2006 with the 42 cm telescope of the Cerro Armazones Observatory which belongs to the Universidad Catolica del Norte, Antofagasta. All four stars are close red dwarf/white dwarf binaries which could have formed be recent common envelope events. In two of the four cases we detected (or confirmed) significant variability. In one of them, the central star of a planetary nebula Abell 65, we confirmed the rather strong photometric variability with a period very near to 24 hours (Bond and Livio, 1990). In the white dwarf binary HZ9 we detected, for the first time, photometric variations with a period near 0.58 days which corresponds to the known orbital period (Lanning and Pesch, 1981; Stauffer, 1987). The amplitude of this variation is 0.08 mag, it probably refers to reflection of the white dwarf radiation on the surface of the red companion. - These observations are part of a larger on-going project which pretends to identify and to study pre-cataclysmic binaries by means of photometric and spectroscopic methods and to improve, this way, the hitherto poor statistics on the properties of these interesting stars.

  16. Annual Climatology of the Diurnal Cycle on the Canadian Prairies

    Directory of Open Access Journals (Sweden)

    Alan K Betts

    2016-01-01

    Full Text Available We show the annual climatology of the diurnal cycle, stratified by opaque cloud, using the full hourly resolution of the Canadian Prairie data. The opaque cloud field itself has distinct cold and warm season diurnal climatologies; with a near-sunrise peak of cloud in the cold season and an early afternoon peak in the warm season. There are two primary climate states on the Canadian Prairies, separated by the freezing point of water, because a reflective surface snow cover acts as a climate switch. Both cold and warm season climatologies can be seen in the transition months of November, March and April with a large difference in mean temperature. In the cold season with snow, the diurnal ranges of temperature and relative humidity increase quasi-linearly with decreasing cloud, and increase from December to March with increased solar forcing. The warm season months, April to September, show a homogeneous coupling to the cloud cover, and a diurnal cycle of temperature and humidity that depends only on net longwave. Our improved representation of the diurnal cycle shows that the warm season coupling between diurnal temperature range and net longwave is weakly quadratic through the origin, rather than the linear coupling shown in earlier papers. We calculate the conceptually important 24-h imbalances of temperature and relative humidity (and other thermodynamic variables as a function of opaque cloud cover. In the warm season under nearly clear skies, there is a warming of +2oC and a drying of -6% over the 24-h cycle, which is about 12% of their diurnal ranges. We summarize results on conserved variable diagrams and explore the impact of surface windspeed on the diurnal cycle in the cold and warm seasons. In all months, the fall in minimum temperature is reduced with increasing windspeed, which reduces the diurnal temperature range. In July and August, there is an increase of afternoon maximum temperature and humidity at low windspeeds, and a

  17. The impact of revised simplified Arakawa-Schubert scheme on the simulation of mean and diurnal variability associated with active and break phases of Indian summer monsoon using CFSv2

    Science.gov (United States)

    Ganai, Malay; Krishna, R. Phani Murali; Mukhopadhyay, P.; Mahakur, M.

    2016-08-01

    The impact of revised simplified Arakawa-Schubert (RSAS) convective parameterization scheme in Climate Forecast System (CFS) version 2 (CFSv2) on the simulation of active and break phases of Indian summer monsoon (ISM) has been investigated. The results revealed that RSAS showed better fidelity in simulating monsoon features from diurnal to daily scales during active and break periods as compared to SAS simulation. Prominent improvement can be noted in simulating diurnal phase of precipitation in RSAS over central India (CI) and equatorial Indian Ocean (EIO) region during active periods. The spatial distribution of precipitation largely improved in RSAS simulation during active and break episodes. CFSv2 with SAS simulation has noticeable dry bias over CI and wet bias over EIO region which appeared to be largely reduced in RSAS simulation during both phases of the intraseasonal oscillation (ISO). During active periods, RSAS simulates more realistic probability distribution function (PDF) in good agreement with the observation. The relative improvement has been identified in outgoing longwave radiation, monsoon circulations, and vertical velocities in RSAS over SAS simulation. The improvement of rainfall distribution appears to be contributed by proper simulation of convective rainfall in RSAS. CFSv2 with RSAS simulation is able to simulate observed diurnal cycle of rainfall over CI. It correctly reproduces the time of maximum rainfall over CI. It is found that the improved feedback between moisture and convective processes in RSAS may be attributed to its improved simulation. Besides improvement, RSAS could not reproduce proper tropospheric temperature, cloud hydrometeors over ISM domain which shows the scope for future development.

  18. Photometric Characteristics of Lunar Terrains

    Science.gov (United States)

    Sato, Hiroyuki; Hapke, Bruce W.; Denevi, Brett W.; Robinson, Mark

    2016-10-01

    The photometric properties of the lunar depend on albedo, surface roughness, porosity, and the internal/external structure of particles. Hapke parameter maps derived using a bidirectional reflectance model [Hapke, 2012] from Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC) images demonstrated the spatial and spectral variation of the photometric properties of the Moon [Sato et al., 2014]. Using the same methodology, here we present the photometric characteristics of typical lunar terrains, which were not systematically analyzed in the previous study.We selected five representative terrain types: mare, highland, swirls, and two Copernican (fresh) crater ejecta (one mare and one highlands example). As for the datasets, we used ~39 months of WAC repeated observations, and for each image pixel, we computed latitude, longitude, incidence, emission, and phase angles using the WAC GLD100 stereo DTM [Scholten et al., 2012]. To obtain similar phase and incidence angle ranges, all sampling sites are near the equator and in the vicinity of Reiner Gamma. Three free Hapke parameters (single scattering albedo: w, HG2 phase function parameter: c, and angular width of SHOE: hs) were then calculated for the seven bands (321-689 nm). The remaining parameters were fixed by simplifying the model [Sato et al., 2014].The highlands, highland ejecta, and swirl (Reiner Gamma) showed clearly higher w than the mare and mare ejecta. The derived c values were lower (less backscattering) for the swirl and higher (more backscattering) for the highlands (and ejecta) relative to the other sites. Forward scattering materials such as unconsolidated transparent crystalline materials might be relatively enriched in the swirl. In the highlands, anorthositic agglutinates with dense internal scattering could be responsible for the strong backscattering. The mare and mare ejecta showed continuously decreasing c from UV to visible wavelengths. This might be caused by the FeO-rich pyroxene

  19. On the diurnal ranges of Sea Surface Temperature (SST) in the north Indian Ocean

    Indian Academy of Sciences (India)

    S S C Shenoi; N Nasnodkar; G Rajesh; K Jossia Joseph; I Suresh; A M Almeida

    2009-10-01

    This paper describes the variability in the diurnal range of SST in the north Indian Ocean using in situ measurements and tests the suitability of simple regression models in estimating the diurnal range.SST measurements obtained from 1556 drifting and 25 moored buoys were used to determine the diurnal range of SSTs.The magnitude of diurnal range of SST was highest in spring and lowest in summer monsoon.Except in spring,nearly 75 –80%of the observations reported diurnal range below 0.5°C.The distributions of the magnitudes of diurnal warming across the three basins of north Indian Ocean (Arabian Sea,Bay of Bengal and Equatorial Indian Ocean)were similar except for the differences between the Arabian Sea and the other two basins during November-February (winter monsoon)and May.The magnitude of diurnal warming that depended on the location of temperature sensor below the water level varied with seasons.In spring,the magnitude of diurnal warming diminished drastically with the increase in the depth of temperature sensor.The diurnal range estimated using the drifting buoy data was higher than the diurnal range estimated using moored buoys fitted with temperature sensors at greater depths. A simple regression model based on the peak solar radiation and average wind speed was good enough to estimate the diurnal range of SST at ∼1.0 m in the north Indian Ocean during most of the seasons except under low wind-high solar radiation conditions that occur mostly during spring. The additional information on the rate of precipitation is found to be redundant for the estimation of the magnitude of diurnal warming at those depths.

  20. Kernel PCA for type Ia supernovae photometric classification

    CERN Document Server

    Ishida, Emille E O

    2013-01-01

    The problem of photometric identification will be extremely important for large surveys in the next decade. In this work, we propose the use of KPCA combined with k = 1 nearest neighbor algorithm (KPCA+1NN) as a framework for SNe photometric classification. The method does not rely on information about redshift or local enviromental variables, so it is less sensitive to bias than its template fitting counterparts. We applied the method to $\\approx$ 20000 SNe light curve released after the \\textit{Supernova Photometric Classification Challenge} (SNPCC). Results for the photometric sample achieved up to 89% efficiency (eff), 97% purity (pur), 96% successful classification (SC) rates and figure of merit (FoM) of 0.79 (SNR$\\geq$5). If we impose no SNR cuts, we obtain up to 64% eff, 43% pur, 46% SC and FoM of 0.10. We also present the classification results using only pre-maximum epoches, obtaining 80% eff, 73% pur, 84% SC and FoM of 0.32 (SNR$\\geq$5). Comparing the performance of our classifier with MLCS2k2 fit p...

  1. Kepler Mission Design, Realized Photometric Performance, and Early Science

    CERN Document Server

    Koch, David G; Basri, Gibor; Batalha, Natalie M; Brown, Timothy M; Caldwell, Douglas; Christensen-Dalsgaard, Joergen; Cochran, William D; DeVore, Edna; Dunham, Edward W; Gautier, Thomas N; Geary, John C; Gilliland, Ronald L; Gould, Alan; Jenkins, Jon; Kondo, Yoji; Latham, David W; Lissauer, Jack J; Marcy, Geoffrey; Monet, David; Sasselov, Dimitar; Boss, Alan; Brownlee, Donald; Caldwell, John; Dupree, Andrea K; Howell, Steve B; Kjeldsen, Hans; Meibom, Soeren; Morrison, David; Owen, Tobias; Reitsema, Harold; Tarter, Jill; Bryson, Stephen T; Dotson, Jessie L; Gazis, Paul; Haas, Michael R; Kolodziejczak, Jeffrey; Rowe, Jason F; Van Cleve, Jeffrey E; Allen, Christopher; Chandrasekaran, Hema; Clarke, Bruce D; Li, Jie; Quintana, Elisa V; Tenenbaum, Peter; Twicken, Joseph D; Wu, Hayley

    2010-01-01

    The Kepler Mission, launched on Mar 6, 2009 was designed with the explicit capability to detect Earth-size planets in the habitable zone of solar-like stars using the transit photometry method. Results from just forty-three days of data along with ground-based follow-up observations have identified five new transiting planets with measurements of their masses, radii, and orbital periods. Many aspects of stellar astrophysics also benefit from the unique, precise, extended and nearly continuous data set for a large number and variety of stars. Early results for classical variables and eclipsing stars show great promise. To fully understand the methodology, processes and eventually the results from the mission, we present the underlying rationale that ultimately led to the flight and ground system designs used to achieve the exquisite photometric performance. As an example of the initial photometric results, we present variability measurements that can be used to distinguish dwarf stars from red giants.

  2. Optimal multihump filter for photometric redshifts

    OpenAIRE

    Budavari, Tamas; Szalay, Alexander S.; Csabai, Istvan; Connolly, Andrew J.; Tsvetanov, Zlatan

    2001-01-01

    We propose a novel type filter for multicolor imaging to improve on the photometric redshift estimation of galaxies. An extra filter - specific to a certain photometric system - may be utilized with high efficiency. We present a case study of the Hubble Space Telescope's Advanced Camera for Surveys and show that one extra exposure could cut down the mean square error on photometric redshifts by 34% over the z

  3. Sloan Digital Sky Survey Photometric Calibration Revisited

    Science.gov (United States)

    Marriner, J.

    2016-05-01

    The Sloan Digital Sky Survey calibration is revisited to obtain the most accurate photometric calibration. A small but significant error is found in the flat-fielding of the Photometric telescope used for calibration. Two SDSS star catalogs are compared and the average difference in magnitude as a function of right ascension and declination exhibits small systematic errors in relative calibration. The photometric transformation from the SDSS Photometric Telescope to the 2.5 m telescope is recomputed and compared to synthetic magnitudes computed from measured filter bandpasses.

  4. Sloan Digital Sky Survey Photometric Calibration Revisited

    Energy Technology Data Exchange (ETDEWEB)

    Marriner, John; /Fermilab

    2012-06-29

    The Sloan Digital Sky Survey calibration is revisited to obtain the most accurate photometric calibration. A small but significant error is found in the flat-fielding of the Photometric telescope used for calibration. Two SDSS star catalogs are compared and the average difference in magnitude as a function of right ascension and declination exhibits small systematic errors in relative calibration. The photometric transformation from the SDSS Photometric Telescope to the 2.5 m telescope is recomputed and compared to synthetic magnitudes computed from measured filter bandpasses.

  5. VizieR Online Data Catalog: Photometric standards around gravitational lenses (Nakos+ 2003)

    Science.gov (United States)

    Nakos, T.; Ofek, E. O.; Boumis, P.; Cuypers, J.; Sinachopoulos, D.; van Dessel, E.; Gal-Yam, A.; Papamastorakis, J.

    2003-08-01

    We present a catalog of secondary photometric standard stars in the neighborhood of 14 gravitationally lensed quasars. These stars were verified to be non variable using long-term monitoring. The instrumental magnitudes of the new standard stars have been transformed to the Johnson-Cousins BV(RI)c photometric system. For ten gravitational lenses (GLs) we also provide the BV(RI)c mean magnitudes of the integrated flux of all the lens components, for the epochs of the photometric calibration. (3 data files).

  6. Diurnal variations in water vapor over Central and South America

    Science.gov (United States)

    Meza, Amalia; Mendoza, Luciano; Clara, Bianchi

    2017-04-01

    Diurnal variations in atmospheric integrated water vapor (IWV) are studied employing IWV estimates, with a 30 minutes sampling rate, derived from Global Navigation Satellite Systems (GNSS) observations during the period 2007-2013. The analysis was performed in 70 GNSS tracking sites (GPS + GLONASS) belonging to Central and South America, which have more than 5 years of data. The selected area involves different climate types, from polar to tropical, and diverse relieves, therefore the patterns of IWV diurnal variations are very different for each station. There are many processes that could induce diurnal variations in atmospheric water vapor (Dai et al, 1999 a,b), the most relevant causes are: surface evapotranspiration, atmospheric large-scale vertical motion, atmospheric low-level moisture convergence and precipitation and vertical mixing (which affects the vertical distribution of water vapor but does not affect the IWV). Firstly, our work study the main characteristics of the IWV diurnal cycle (and for surface temperature, T) obtained for all stations together, using Principal Component Analysis (PCA). First and second PCA modes highlight the global main behaviors of IWV variability for all stations. The first mode on IWV represent the 70% of the variability and could be related to the surface evapotranspiration, while the second mode (27 % of the variability) is practically in counter phase to T variability (its first mode represent the 97% of the variability), therefore this mode could be related to breeze regime. Then, every station is separately analyzed and seasonal and local variations (relative to the relives) are detected, these results spotlight, among other characteristics, the sea and mountain breeze regime. This presentation shows the first analysis of IWV diurnal cycle performed over Central and South America and another original characteristic is PCA technique employed to infer the results. Reference: Dai, A., K. E. Trenberth, and T. R. Karl

  7. Cosmology with photometric redshift surveys

    CERN Document Server

    Blake, C; Blake, Chris; Bridle, Sarah

    2004-01-01

    We explore the utility of future photometric redshift imaging surveys for delineating the large-scale structure of the Universe, and assess the resulting constraints on the cosmological model. We perform two complementary types of analysis: (1) We quantify the statistical confidence and accuracy with which such surveys will be able to detect and measure characteristic features in the clustering power spectrum such as the acoustic oscillations and the turnover, in a model-independent fashion. For example, we show that a 10000 sq deg imaging survey with depth r = 22.5 and photometric redshift accuracy dz/(1+z) = 0.03 will detect the acoustic oscillations with 99.9% confidence, measuring the associated cosmological scale with 2% precision. Such a survey will also detect the turnover with 95% confidence, determining the corresponding scale with 20% accuracy. (2) By assuming a Lambda-CDM cosmology we calculate the confidence with which a non-zero baryon fraction can be deduced from such future surveys. After margi...

  8. Diurnal tides in the Arctic Ocean

    Science.gov (United States)

    Kowalik, Z.; Proshutinsky, A. Y.

    1993-01-01

    A 2D numerical model with a space grid of about 14 km is applied to calculate diurnal tidal constituents K(1) and O(1) in the Arctic Ocean. Calculated corange and cotidal charts show that along the continental slope, local regions of increased sea level amplitude, highly variable phase and enhanced currents occur. It is shown that in these local regions, shelf waves (topographic waves) of tidal origin are generated. In the Arctic Ocean and Northern Atlantic Ocean more than 30 regions of enhanced currents are identified. To prove the near-resonant interaction of the diurnal tides with the local bottom topography, the natural periods of oscillations for all regions have been calculated. The flux of energy averaged over the tidal period depicts the gyres of semitrapped energy, suggesting that the shelf waves are partially trapped over the irregularities of the bottom topography. It is shown that the occurrence of near-resonance phenomenon changes the energy flow in the tidal waves. First, the flux of energy from the astronomical sources is amplified in the shelf wave regions, and afterwards the tidal energy is strongly dissipated in the same regions.

  9. Photometric Covariance in Multi-Band Surveys: Understanding the Photometric Error in the SDSS

    CERN Document Server

    Scranton, R; Szalay, A S; Lupton, R H; Johnston, D; Budavari, T; Brinkmann, J; Fukugita, M; Scranton, Ryan; Connolly, Andrew J.; Szalay, Alexander S.; Lupton, Robert H.; Johnston, David; Budavari, Tamas; Brinkman, John; Fukugita, Masatake

    2005-01-01

    In this paper we describe a detailed analysis of the photometric uncertainties present within the Sloan Digital Sky Survey (SDSS) imaging survey based on repeat observations of approximately 200 square degrees of the sky. We show that, for the standard SDSS aperture systems (petrocounts, counts_model, psfcounts and cmodel_counts), the errors generated by the SDSS photometric pipeline under-estimate the observed scatter in the individual bands. The degree of disagreement is a strong function of aperture and magnitude (ranging from 20% to more than a factor of 2). We also find that the photometry in the five optical bands can be highly correlated for both point sources and galaxies, although the correlation for point sources is almost entirely due to variable objects. Without correcting for this covariance the SDSS color errors could be in over-estimated by a factor of two to three. Combining these opposing effects, the SDSS errors on the colors differ from the observed color variation by approximately 10-20% f...

  10. Precision Cosmology with a New Probabilistic Photometric Redshifts Approach

    Science.gov (United States)

    Carrasco Kind, Matias; Brunner, R. J.

    2013-06-01

    A complete understanding of both dark energy and dark matter remains one of most important challenges in astrophysics today. Recent theoretical and numerical computations have made important progress in quantifying the role of these dark components on the formation and evolution of galaxies through cosmic time, but observational verification of these predictions and the development of new, more stringent constraints has not kept pace. It is in this context that, photometric redshifts have become more important with the growth of large imaging surveys, such as DES and LSST, that have been designed to address this issue. But their basic implementation has not changed significantly from their original development, as most techniques provide a single photometric redshift estimate and an associated error for the an extragalactic source. In this work, we present a unique and powerful solution that leverages the full information contained in the photometric data to address this cosmological challenge with a new approach that provides accurate photometric redshift probability density functions (PDF) for galaxies. This new approach, which scales efficiently to massive data, efficiently combines standard template fitting techniques with powerful machine learning methods. Included in this framework is our recently developed technique entitled Trees for PhotoZ (TPZ); a new, robust, parallel photometric redshift code that uses prediction trees and random forests to generate photo-z PDFs in a reliable and fast manner. In addition, our approach also provides ancillary information about the internal structure of the data, including the relative importance of variables used during the redshift estimation, an identification of areas in the training sample that provide poor predictions, and an accurate outlier rejection method. We will also present current results of this approach on a variety of datasets and discuss, by using specific examples, how the full photo-z PDF can be

  11. Diurnal distribution of sunshine probability

    Energy Technology Data Exchange (ETDEWEB)

    Aydinli, S.

    1982-01-01

    The diurnal distribution of the sunshine probability is essential for the predetermination of average irradiances and illuminances by solar radiation on sloping surfaces. The most meteorological stations have only monthly average values of the sunshine duration available. It is, therefore, necessary to compute the diurnal distribution of sunshine probability starting from the average monthly values. It is shown how the symmetric component of the distribution of the sunshine probability which is a consequence of a ''sidescene effect'' of the clouds can be calculated. The asymmetric components of the sunshine probability depending on the location and the seasons and their influence on the predetermination of the global radiation are investigated and discussed.

  12. Diurnal variations in water vapor over Central and South America

    Science.gov (United States)

    Meza, Amalia; Mendoza, Luciano; Bianchi, Clara

    2016-07-01

    Diurnal variations in atmospheric integrated water vapor (IWV) are studied employing IWV estimates, with a 30 minutes sampling rate, derived from Global Navigation Satellite Systems (GNSS) observations during the period 2007-2013. The analysis was performed in 73 GNSS tracking sites (GPS + GLONASS) which have more than 5 years of data. The selected area involves different climate types, from polar to tropical, with different diurnal variations of the integrated total humidity content. There are many processes that could induce diurnal variations in atmospheric water vapor (Dai et al, 1999 a,b), the most relevant causes are: surface evapotranspiration, atmospheric large-scale vertical motion, atmospheric low-level moisture convergence and precipitation and vertical mixing (which affects the vertical distribution of water vapor but does not affect the IWV). The numerical tools, Singular Value Decomposition and classical Multidimensional Scaling methods, are used to study these variations, considering the measurements made at each stations, as sample in the analysis. The aim of this investigation is to identify the IWV variability with respect to the local time associated to the different climate regions. In order to improve our analysis, all available weather information, such as radiosondes measurements (which are few), measurements of pressure and temperature and Numerical Weather Models reanalysis data, are used. Reference: Dai, A., K. E. Trenberth, and T. R. Karl, 1999 a: Effects of clouds, soil moisture, precipitation and water vapor on diurnal temperature range. J. Climate, 12, 2451-2473. Dai, A., F. Giorgi, and K. E. Trenberth, 1999 b: Observed and model simulated precipitation diurnal cycle over the contiguous United States.J. Geophys. Res., 104, 6377-6402. KEYWORDS: water vapor, diurnal cycle, GNSS

  13. CuBANz: Photometric redshift estimator

    Science.gov (United States)

    Samui, Saumyadip; Pal, Shanoli Samui

    2016-09-01

    CuBANz is a photometric redshift estimator code for high redshift galaxies that uses the back propagation neural network along with clustering of the training set, making it very efficient. The training set is divided into several self learning clusters with galaxies having similar photometric properties and spectroscopic redshifts within a given span. The clustering algorithm uses the color information (i.e. u-g, g-r etc.) rather than the apparent magnitudes at various photometric bands, as the photometric redshift is more sensitive to the flux differences between different bands rather than the actual values. The clustering method enables accurate determination of the redshifts. CuBANz considers uncertainty in the photometric measurements as well as uncertainty in the neural network training. The code is written in C.

  14. A Photometric Study of Stars in the MBM 12 Association

    CERN Document Server

    Herbst, W; Hawley, W P; Herbst, William; Williams, Eric C.; Hawley, Wendy P.

    2004-01-01

    We have monitored four fields containing nine previously identified members of the MBM 12 association to search for photometric variability and periodicity in these pre-main sequence stars. Seven of the nine are found to be variable and definite periodicity (of 1.2, 2.6 and 6.2 days) is found for three of them, including the classical T Tauri star LkH-alpha 264. Two other members are possibly periodic but each requires confirmation. In addition, a "field" star that is associated with the X-ray source RX J0255.9+2005 was discovered to be a variable with a period of 4.2 days. Our results indicate that the photometric variability characteristics of the known MBM 12 association members are typical of what is found in ~few My old stellar groups such as IC 348, supporting arguments for a similar age. In particular, there is a mix of periodic and non-periodic variables with typical amplitudes (in Cousins I) of 0.1-0.5 mag, in addition to a small number of larger amplitude variables. The periods, as a group, are some...

  15. Reconstructing the photometric light curves of Earth as a planet along its history

    CERN Document Server

    Sanromá, Esther

    2011-01-01

    By utilizing satellite-based estimations of the distribution of clouds, we have studied the Earth's large-scale cloudiness behavior according to latitude and surface types (ice, water, vegetation and desert). These empirical relationships are used here to reconstruct the possible cloud distribution of historical epochs of the Earth's history such as the Late Cretaceous (90 Ma ago), the Late Triassic (230 Ma ago), the Mississippian (340 Ma ago), and the Late Cambrian (500 Ma ago), when the landmass distributions were different from today's. With this information, we have been able to simulate the globally-integrated photometric variability of the planet at these epochs. We find that our simple model reproduces well the observed cloud distribution and albedo variability of the modern Earth. Moreover, the model suggests that the photometric variability of the Earth was probably much larger in past epochs. This large photometric variability could improve the chances for the difficult determination of the rotation...

  16. Photo-z-SQL: integrated, flexible photometric redshift computation in a database

    CERN Document Server

    Beck, Róbert; Budavári, Tamás; Szalay, Alexander S; Csabai, István

    2016-01-01

    We present a flexible template-based photometric redshift estimation framework, implemented in C#, that can be seamlessly integrated into a SQL database (or DB) server and executed on-demand in SQL. The DB integration eliminates the need to move large photometric datasets outside a database for redshift estimation, and utilizes the computational capabilities of DB hardware. The code is able to perform both maximum likelihood and Bayesian estimation, and can handle inputs of variable photometric filter sets and corresponding broad-band magnitudes. It is possible to take into account the full covariance matrix between filters, and filter zero points can be empirically calibrated using measurements with given redshifts. The list of spectral templates and the prior can be specified flexibly, and the expensive synthetic magnitude computations are done via lazy evaluation, coupled with a caching of results. Parallel execution is fully supported. For large upcoming photometric surveys such as the LSST, the ability t...

  17. TPZ : Photometric redshift PDFs and ancillary information by using prediction trees and random forests

    CERN Document Server

    Kind, M Carrasco

    2013-01-01

    With the growth of large photometric surveys, accurately estimating photometric redshifts, preferably as a probability density function (PDF), and fully understanding the implicit systematic uncertainties in this process has become increasingly important. In this paper, we present a new, publicly available, parallel, machine learning algorithm that generates photometric redshift PDFs by using prediction trees and random forest techniques, which we have named TPZ. This new algorithm incorporates measurement errors into the calculation while also dealing efficiently with missing values in the data. In addition, our implementation of this algorithm provides supplementary information regarding the data being analyzed, including unbiased estimates of the accuracy of the technique without resorting to a validation data set, identification of poor photometric redshift areas within the parameter space occupied by the spectroscopic training data, a quantification of the relative importance of the variables used to con...

  18. Do Diurnal Aerosol Changes Affect Daily Average Radiative Forcing?

    Energy Technology Data Exchange (ETDEWEB)

    Kassianov, Evgueni I.; Barnard, James C.; Pekour, Mikhail S.; Berg, Larry K.; Michalsky, Joseph J.; Lantz, K.; Hodges, G. B.

    2013-06-17

    Strong diurnal variability of aerosol has been observed frequently for many urban/industrial regions. How this variability may alter the direct aerosol radiative forcing (DARF), however, is largely unknown. To quantify changes in the time-averaged DARF, we perform an assessment of 29 days of high temporal resolution ground-based data collected during the Two-Column Aerosol Project (TCAP) on Cape Cod, which is downwind of metropolitan areas. We demonstrate that strong diurnal changes of aerosol loading (about 20% on average) have a negligible impact on the 24-h average DARF, when daily averaged optical properties are used to find this quantity. However, when there is a sparse temporal sampling of aerosol properties, which may preclude the calculation of daily averaged optical properties, large errors (up to 100%) in the computed DARF may occur. We describe a simple way of reducing these errors, which suggests the minimal temporal sampling needed to accurately find the forcing.

  19. Photometrical Observations "SBIRS GEO-2"

    Science.gov (United States)

    Sukhov, P. P.; Epishev, V. P.; Karpenko, G. F.; Sukhov, K. P.; Kudak, V. I.

    Photometrical observations GSS "SBIRS GEO 2" in B,V,R filters were carried near the equinoxes 2014-2015. Used velocity electrophotometer based on the FEU-79 in the pulse-counting mode. Received more than 25 light curves. From the known dimensions are defined; effective reflecting area - Sγλ, the spectral reflectance index - γλ, periods of light variation. Color-indices showed that in the reflected light flux from the GSS prevails "red" component. In the light curves are periodically dips and specular flash. This shows that GSS orbit is not in a static position specified triaxial orientation as in dynamic motion. Assumed following dynamics of the satellite "SBIRS GEO 2" in orbit. Helical scanning the Earth's surface visible infrared sensors satellite occurs with a period P1 = 15.66 sec. and swinging of the GSS about the direction of the motion vector of the satellite in an orbit with P2 = 62.64 sec., from the northern to the southern pole. Thus, during the period of swinging GSS going on 2 scan the visible part of the northern and southern hemispheres. In some dates observations dynamics work satellite in orbit changed.

  20. Photometric Metallicities in Bootes I

    CERN Document Server

    Hughes, J; Dotter, A; Geisler, D

    2014-01-01

    We present new Stromgren and Washington data sets for the Bootes I dwarf galaxy, and combine them with the available SDSS photometry. The goal of this project is to refine a ground-based, practical, accurate method to determine age and metallicity for individual stars in Bootes I that can be selected in an unbiased imaging survey, without having to take spectra. We produce photometric metallicities from Stromgren and Washington photometry, for stellar systems with a range of $-1.0>[Fe/H]>-3.5$. To avoid the decrease in sensitivity of the Stromgren metallicity index on the lower red-giant branch, we replace the Stromgren v-filter with the broader Washington C-filter; we find that $CT_1by$ is the most successful filter combination, for individual stars with $[Fe/H]<-2.0$, to maintain ~0.2 dex $[Fe/H]$-resolution over the whole red-giant branch. We demonstrate that we can break the isochrones' age-metallicity degeneracy with these filters, using stars with log g=2.5-3.0, which have less than a 2% change in th...

  1. Evaluation of the sensitivity of the Amazonian diurnal cycle to convective intensity in reanalyses

    Science.gov (United States)

    Itterly, Kyle F.; Taylor, Patrick C.

    2017-02-01

    Model parameterizations of tropical deep convection are unable to reproduce the observed diurnal and spatial variability of convection in the Amazon, which contributes to climatological biases in the water cycle and energy budget. Convective intensity regimes are defined using percentiles of daily minimum 3-hourly averaged outgoing longwave radiation (OLR) from Clouds and the Earth's Radiant Energy System (CERES). This study compares the observed spatial variability of convective diurnal cycle statistics for each regime to MERRA-2 and ERA-Interim (ERA) reanalysis data sets. Composite diurnal cycle statistics are computed for daytime hours (06:00-21:00 local time) in the wet season (December-January-February). MERRA-2 matches observations more closely than ERA for domain averaged composite diurnal statistics—specifically precipitation. However, ERA reproduces mesoscale features of OLR and precipitation phase associated with topography and the propagation of the coastal squall line. Both reanalysis models are shown to underestimate extreme convection.

  2. Photometric normalization of LROC WAC images

    Science.gov (United States)

    Sato, H.; Denevi, B.; Robinson, M. S.; Hapke, B. W.; McEwen, A. S.; LROC Science Team

    2010-12-01

    variability of the regolith from region to region. As the fitting area increases, the accuracy of curve fitting decreases due to the larger variety of albedo, topography, and composition. Thus we have adopted an albedo-dependent photometric normalization routine. Phase curves are derived for discreet bins of preliminary normalized reflectance calculated from Clementine global mosaic in a fitting area that is composed of predominantly mare in Oceanus Procellarum. The global WAC mosaic was then corrected pixel-by-pixel according to its preliminary reflectance map with satisfactory results. We observed that the phase curves per normalized-reflectance bins become steeper as the reflectance value increases. Further filtering by using FeO, TiO2, or optical maturity [5] for parameter calculations may help elucidate the effects of surface composition and maturity on photometric properties of the surface. [1] Hapke, B.W. (1993) Theory of Reflectance and Emittance Spectroscopy, Cambridge Univ. Press. [2] Schoenberg (1925) Ada. Soc. Febb., vol. 50. [3] Hillier et al. (1999) Icarus 141, 205-225. [4] McEwen (1991) Icarus 92, 298-311. [5] Lucey et al. (2000) JGR, v105, no E8, p20377-20386.

  3. Photometric redshift and classification for the XMM-COSMOS sources

    CERN Document Server

    Salvato, M; Ilbert, O; Zamorani, G; Brusa, M; Scoville, N; Rau, A; Capak, P; Arnouts, S; Aussel, H; Bolzonella, M; Buongiorno, A; Cappelluti, N; Caputi, K; Civano, F; Cook, R; Elvis, M; Gilli, R; Jahnke, K; Kartaltepe, J S; Impey, C D; Lamareille, F; Le Floc'h, E; Lilly, S; Mainieri, V; McCarthy, P; McCracken, H; Mignoli, M; Mobasher, B; Murayama, T; Sasaki, S; Sanders, D B; Schiminovich, D; Shioya, Y; Shopbell, P; Silvermann, J; Smolcic, V; Surace, J; Taniguchi, Y; Thompson, D; Trump, J R; Urry, M; Zamojski, M

    2008-01-01

    We present photometric redshifts and spectral energy distribution (SED) classifications for a sample of 1542 optically identified sources detected with XMM in the COSMOS field. Our template fitting classifies 46 sources as stars and 464 as non-active galaxies, while the remaining 1032 require templates with an AGN contribution. High accuracy in the derived photometric redshifts was accomplished as the result of 1) photometry in up to 30 bands with high significance detections, 2) a new set of SED templates including 18 hybrids covering the far-UV to mid-infrared, which have been constructed by the combination of AGN and non-active galaxies templates, and 3) multi-epoch observations that have been used to correct for variability (most important for type 1 AGN). The reliability of the photometric redshifts is evaluated using the sub-sample of 442 sources with measured spectroscopic redshifts. We achieved an accuracy of $\\sigma_{\\Delta z/(1+z_{spec})} = 0.014$ for i$_{AB}^*<$22.5 ($\\sigma_{\\Delta z/(1+z_{spec...

  4. Long-term Photometric Behavior of Outbursting AM CVn Systems

    CERN Document Server

    Levitan, David; Prince, Thomas A; Kulkarni, Shrinivas R; Laher, Russ; Ofek, Eran O; Sesar, Branimir; Surace, Jason

    2014-01-01

    The AM CVn systems are a class of He-rich, post-period minimum, semi-detached, ultra-compact binaries. Their long-term light curves have been poorly understood due to the few systems known and the long (hundreds of days) recurrence times between outbursts. We present combined photometric light curves from the LINEAR, CRTS, and PTF synoptic surveys to study the photometric variability of these systems over an almost 10 yr period. These light curves provide a much clearer picture of the outburst phenomena that these systems undergo. We characterize the photometric behavior of most known outbursting AM CVn systems and establish a relation between their outburst properties and the systems' orbital periods. We also explore why some systems have only shown a single outburst so far and expand the previously accepted phenomenological states of AM CVn systems. We conclude that the outbursts of these systems show evolution with respect to the orbital period, which can likely be attributed to the decreasing mass transfe...

  5. Novel Methods for Predicting Photometric Redshifts

    Data.gov (United States)

    National Aeronautics and Space Administration — We calculate photometric redshifts from the Sloan Digital Sky Survey Main Galaxy Sample, The Galaxy Evolution Explorer All Sky Survey, and The Two Micron All Sky...

  6. CALIBRATION OF THE MEARTH PHOTOMETRIC SYSTEM: OPTICAL MAGNITUDES AND PHOTOMETRIC METALLICITY ESTIMATES FOR 1802 NEARBY M-DWARFS

    Energy Technology Data Exchange (ETDEWEB)

    Dittmann, Jason A.; Irwin, Jonathan M.; Charbonneau, David; Newton, Elisabeth R. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States)

    2016-02-20

    The MEarth Project is a photometric survey systematically searching the smallest stars near the Sun for transiting rocky planets. Since 2008, MEarth has taken approximately two million images of 1844 stars suspected to be mid-to-late M dwarfs. We have augmented this survey by taking nightly exposures of photometric standard stars and have utilized this data to photometrically calibrate the MEarth system, identify photometric nights, and obtain an optical magnitude with 1.5% precision for each M dwarf system. Each optical magnitude is an average over many years of data, and therefore should be largely immune to stellar variability and flaring. We combine this with trigonometric distance measurements, spectroscopic metallicity measurements, and 2MASS infrared magnitude measurements in order to derive a color–magnitude–metallicity relation across the mid-to-late M dwarf spectral sequence that can reproduce spectroscopic metallicity determinations to a precision of 0.1 dex. We release optical magnitudes and metallicity estimates for 1567 M dwarfs, many of which did not have an accurate determination of either prior to this work. For an additional 277 stars without a trigonometric parallax, we provide an estimate of the distance, assuming solar neighborhood metallicity. We find that the median metallicity for a volume-limited sample of stars within 20 pc of the Sun is [Fe/H] = −0.03 ± 0.008, and that 29/565 of these stars have a metallicity of [Fe/H] = −0.5 or lower, similar to the low-metallicity distribution of nearby G dwarfs. When combined with the results of ongoing and future planet surveys targeting these objects, the metallicity estimates presented here will be important for assessing the significance of any putative planet–metallicity correlation.

  7. Spectroscopic and Photometric Observations of Kepler Asteroseismic Targets

    CERN Document Server

    Molenda-Zakowicz, J; Kopacki, G; Frasca, A; Catanzaro, G; Latham, D W; Niemczura, E; Narwid, A; Steslicki, M; Arentoft, T; Kubat, J; Drobek, D; Dimitrow, W; 10.1063/1.3246557

    2012-01-01

    We summarize our ground-based program of spectroscopic and photometric observations of the asteroseismic targets of the Kepler space telescope. We have already determined atmospheric parameters, projected velocity of rotation, and radial velocity of 62 Kepler asteroseismic targets and 33 other stars in the Kepler field of view. We discovered six single-lined and two double-lined spectroscopic binaries, we determined the interstellar reddening for 29 stars in the Kepler field of view, and discovered three delta Sct, two gamma Dor and 14 other variable stars in the field of NGC 6866.

  8. The effect of photometric and geometric context on photometric and geometric lightness effects.

    Science.gov (United States)

    Lee, Thomas Y; Brainard, David H

    2014-01-24

    We measured the lightness of probe tabs embedded at different orientations in various contextual images presented on a computer-controlled stereo display. Two background context planes met along a horizontal roof-like ridge. Each plane was a graphic rendering of a set of achromatic surfaces with the simulated illumination for each plane controlled independently. Photometric context was varied by changing the difference in simulated illumination intensity between the two background planes. Geometric context was varied by changing the angle between them. We parsed the data into separate photometric effects and geometric effects. For fixed geometry, varying photometric context led to linear changes in both the photometric and geometric effects. Varying geometric context did not produce a statistically reliable change in either the photometric or geometric effects.

  9. Assessing the diurnal cycle of precipitation in a multi-scale climate model

    Directory of Open Access Journals (Sweden)

    Michael S Pritchard

    2009-10-01

    Full Text Available A promising result that has emerged from the new Multi-scale Modeling Framework (MMF approach to atmospheric modeling is a global improvement in the daily timing of peak precipitation over the continents, which is suggestive of improved moist dynamics at diurnal timescales overall. We scrutinize the simulated seasonal composite diurnal cycle of precipitation in an MMF developed by the Center for Multiscale Modeling of Atmospheric Processes (CMMAP using a comprehensive suite of diurnal cycle diagnostics including traditional harmonic analysis, and non-traditional diagnostics such as the broadness of the peak precipitation in the mean summer day, reduced dimension transect analysis, and animations of the full spatial and temporal variability of the composite mean summer day. Precipitation in the MMF is evaluated against multi-satellite merged satellite data and a control simulation with a climate model that employs conventional cloud and boundary layer parameterizations. Our analysis highlights several improved features of the diurnal cycle of precipitation in the multi-scale climate model: It is less sinusoidal over the most energetic diurnal rainfall regimes, more horizontally inhomogeneous within continents and oceans, and more faithful to observed structural transitions in the composite diurnal cycle chronology straddling coastlines than the conventional climate model. A regional focus on North America links a seasonal summer dry bias over the continental United States in the CMMAP MMF at T42 resolution to its inability to capture diurnally propagating precipitation signals associated with organized convection in the lee of the Rockies. The chronology of precipitation events elsewhere in the vicinity of North America is improved in the MMF, especially over sea breeze circulation regions along the eastern seaboard and the Gulf of Mexico, as well as over the entirety of the Gulf Stream. Comparison of the convective heating and moistening

  10. Quasi-Biennial Oscillation signatures in the diurnal tidal winds over Cachoeira Paulista

    Science.gov (United States)

    Rodrigues de Araujo, Luciana; Jacobi, Christoph; Batista, Paulo; Lima, Lourivaldo

    2016-07-01

    The solar diurnal tidal plays an important role in the Mesosphere and Lower Thermosphere (MLT) region at low latitudes, in which its amplitude for horizontal winds maximizes around 20 degrees. The tides are excited in the lower atmosphere and stratosphere and can be affected by short and long-term local variations during their upward propagation. In this work, the meteor winds obtained over Cachoeira Paulista (22.7° S, 45.0° W), Brazil, have been used to investigate interannual variability in the amplitude of the diurnal tidal winds. The monthly diurnal tidal displays year to year variations. Amplitudes are strongest when the equatorial quasi-biennial oscillation (QBO) at the 30 mb level is eastward. This behavior can be observed in all seasons in the meridional component, whilst it is more clearly expressed during austral autumn in the zonal component, just when the diurnal tidal is strongest at this latitude.

  11. Photometric redshifts for the CFHTLS-Wide

    CERN Document Server

    Brimioulle, Fabrice; Seitz, Stella; Bender, Ralf; Snigula, Jan

    2008-01-01

    We want to derive bias free, accurate photometric redshifts for those fields of the CFHTLS-Wide data which are covered in the u*, g', r', i' and z' filters and are public on January 2008. These are 37 square degrees in the W1, W3 and W4 fields with photometric data for a total of 2.597.239 galaxies. We use the photometric redshift code PHOTO-z of Bender et al. (2001). We compare our redshifts for the W1, W3 and W4 fields to about 7500 spectroscopic redshifts from the VVDS therein. For galaxies with 17.5 <= i' AB <= 22.5 the accuracies and outlier rates become sigma=0.033, eta~2 % for W1, sigma=0.037, eta~2% for W3 and sigma=0.035, eta~2.5 % outliers for W4 fields. For the total galaxy sample with about 9000 spectroscopic redshifts from VVDS, DEEP2 or SDSS we obtain a sigma=0.04 and eta~5.7% for the PHOTO-z redshifts. We consider the photometric redshifts of Erben et al. (2008) which were obtained with exactly the same photometric catalog using the BPZ-redshift code and compare them with our computed red...

  12. Photometric Variations In The Sun And Solar-Type Stars

    Science.gov (United States)

    Giampapa, Mark

    The rich array of solar magnetic field-related phenomena we see occurs not only on stellar counterparts of our Sun but in stars that represent significant departures in their fundamental parameters from those of the Sun. Though these phenomena appear energetically negligible when compared to the total luminosity of stars, they nevertheless govern the angular momentum evolution and modulate the radiative and particle output of the Sun and late-type stars. The term "The Solar-Stellar Connection" has been coined to describe the solar-stellar synergisms in the investigation of the generation, emergence and coupling of magnetic fields with the outer solar-stellar atmosphere to produce what we broadly refer to as magnetic activity. With the discovery of literally thousands of planets beyond our solar system, the Solar-Stellar-Planet Connection is quickly emerging as a new area of investigation of the impacts of magnetic activity on exoplanet atmospheres. In parallel with this rapid evolution in our perspectives is the advent of transformative facilities for the study of the Sun and the dynamic Universe. The primary focus of this invited talk will be on photometric variations in solar-type stars and the Sun. These brightness variations are associated with thermal homogeneities typically defined by magnetic structures that are also spatially coincident with key radiative proxies. Photometric variability in solar-type stars and the Sun includes transient brightening, rotational modulation by cool spots and cycle-related variability, each with a characteristic signature in time and wavelength. The emphasis of this presentation will be on the relationship between broadband photometric variations and magnetic field-related activity in solar-type stars and the Sun. Facets of this topic will be discussed both retrospectively and prospectively as we enter a revolutionary, new era for astronomy.

  13. Fine detrending of raw Kepler and MOST photometric data of KIC 6950556 and HD 37633

    Science.gov (United States)

    Mikulášek, Zdeněk; Paunzen, Ernst; Zejda, Miloslav; Semenko, Evgenij; Bernhard, Klaus; Hümmerich, Stefan; Zhang, Jia; Hubrig, Swetlana; Kuschnig, Rainer; Janík, Jan; Jagelka, Miroslav

    2016-07-01

    We present a simple phenomenological method for detrending of raw Kepler and MOST photometry, which is illustrated by means of photometric data processing of two periodically variable chemically peculiar stars, KIC 6950556 and HD 37633. In principle, this method may be applied to any type of periodically variable objects and satellite or ground based photometries. As a by product, we have identified KIC 6950556 as a magnetic chemically peculiar star with an ACV type variability.

  14. Fine detrending of raw Kepler and MOST photometric data of KIC 6950556 and HD 37633

    CERN Document Server

    Mikulasek, Zdenek; Zejda, Miloslav; Semenko, Evgenij; Bernhard, Klaus; Hummerich, Stefan; Zhang, Jia; Hubrig, Swetlana; Kuschnig, Rainer; Janik, Jan; Jagelka, Miroslav

    2016-01-01

    We present a simple phenomenological method for detrending of raw Kepler and MOST photometry, which is illustrated by means of photometric data processing of two periodically variable chemically peculiar stars, KIC 6950556 and HD 37633. In principle, this method may be applied to any type of periodically variable objects and satellite or ground based photometries. As a by product, we have identified KIC 6950556 as a magnetic chemically peculiar star with an ACV type variability.

  15. Defining Photometric Peculiar Type Ia Supernovae

    CERN Document Server

    Gonzalez-Gaitan, S; Pignata, G; Forster, F; Gutierrez, C P; Bufano, F; Galbany, L; Folatelli, G; Phillips, M M; Hamuy, M; Anderson, J P; de Jaeger, T

    2014-01-01

    We present a new photometric identification technique for SN 1991bg-like type Ia supernovae (SNe Ia), i.e. objects with light-curve characteristics such as later primary maxima and absence of secondary peak in redder filters. This method is capable of selecting out this sub-group from the normal type Ia population. Furthermore, we find that recently identified peculiar sub-types such as SNe Iax and super-Chandrasekhar SNe Ia have similar photometric characteristics as 91bg-like SNe Ia, namely the absence of secondary maxima and shoulders at longer wavelengths, and can also be classified with our technique. The similarity of these different SN Ia sub-groups perhaps suggests common physical conditions. This typing methodology permits the photometric identification of peculiar SNe Ia in large up-coming wide field surveys either to study them further or to obtain a pure sample of normal SNe Ia for cosmological studies.

  16. Defining photometric peculiar type Ia supernovae

    Energy Technology Data Exchange (ETDEWEB)

    González-Gaitán, S.; Pignata, G.; Förster, F.; Gutiérrez, C. P.; Bufano, F.; Galbany, L.; Hamuy, M.; De Jaeger, T. [Millennium Institute of Astrophysics, Casilla 36-D, Santiago (Chile); Hsiao, E. Y.; Phillips, M. M. [Carnegie Observatories, Las Campanas Observatory, Casilla 601, La Serena (Chile); Folatelli, G. [Kavli Institute for the Physics and Mathematics of the Universe, the University of Tokyo, Kashiwa 277-8583 (Kavli IPMU, WPI) (Japan); Anderson, J. P., E-mail: sgonzale@das.uchile.cl [European Southern Observatory, Alonso de Córdova 3107, Casilla 19, Santiago (Chile)

    2014-11-10

    We present a new photometric identification technique for SN 1991bg-like type Ia supernovae (SNe Ia), i.e., objects with light curve characteristics such as later primary maxima and the absence of a secondary peak in redder filters. This method is capable of selecting this sub-group from the normal type Ia population. Furthermore, we find that recently identified peculiar sub-types such as SNe Iax and super-Chandrasekhar SNe Ia have photometric characteristics similar to 91bg-like SNe Ia, namely, the absence of secondary maxima and shoulders at longer wavelengths, and can also be classified with our technique. The similarity of these different SN Ia sub-groups perhaps suggests common physical conditions. This typing methodology permits the photometric identification of peculiar SNe Ia in large upcoming wide-field surveys either to study them further or to obtain a pure sample of normal SNe Ia for cosmological studies.

  17. Long Photometric Cycles in Hot Algols

    Science.gov (United States)

    Mennickent, R. E.

    2017-06-01

    We summarize the development of the field of Double Periodic Variables (DPVs, Mennickent et al. 2003) during the last fourteen years, placing these objects in the context of intermediate-mass close interacting binaries similar to β Persei (Algol) and β Lyrae (Sheliak) which are generally called Algols.DPVs show enigmatic long photometric cycles lasting on average about 33 times the orbital period, and have physical properties resembling, in some aspects, β Lyrae. About 200 of these objects have been found in the Galaxy and the Magellanic Clouds. Light curve models and orbitally resolved spectroscopy indicate that DPVs are semi-detached interacting binaries consisting of a near main-sequence B-type star accreting matter from a cooler giant and surrounded by an optically thick disc. This disc contributes a significant fraction of the system luminosity and its luminosity is larger than expected from the phenomenon of mass accretion alone. In some systems, an optically thin disc component is observed in well developed Balmer emission lines. The optically thick disc shows bright zones up to tens percent hotter than the disc, probably indicating shocks resulting from the gas and disc stream dynamics. We conjecture that a hotspot wind might be one of the channels for a mild systemic mass loss, since evidence for jets, winds or general mass loss has been found in β Lyrae, AU Mon, HD 170582, OGLE 05155332-6925581 and V 393 Sco. Also, theoretical work by Van Rensbergen et al. (2008) and Deschamps et al. (2013) suggests that hotspot could drive mass loss from Algols. We give special consideration to the recently published hypothesis for the long cycle, consisting of variable mass transfer driven by a magnetic dynamo (Schleicher and Mennickent 2017). The Applegate (1992) mechanism should modify cyclically the equatorial radius of the chromospherically active donor producing cycles of enhanced mass loss through the inner Lagrangian point. Chromospheric emission in V 393 Sco

  18. Photometric Calibrations for the SIRTF Infrared Spectrograph

    CERN Document Server

    Morris, P W; Herter, T L; Armus, L; Houck, J; Sloan, G

    2002-01-01

    The SIRTF InfraRed Spectrograph (IRS) is faced with many of the same calibration challenges that were experienced in the ISO SWS calibration program, owing to similar wavelength coverage and overlapping spectral resolutions of the two instruments. Although the IRS is up to ~300 times more sensitive and without moving parts, imposing unique calibration challenges on their own, an overlap in photometric sensitivities of the high-resolution modules with the SWS grating sections allows lessons, resources, and certain techniques from the SWS calibration programs to be exploited. We explain where these apply in an overview of the IRS photometric calibration planning.

  19. Perceptual preferences in depth stratification of transparent layers: Photometric and non-photometric factors.

    Science.gov (United States)

    Delogu, Franco; Fedorov, George; Belardinelli, Marta Olivetti; van Leeuwen, Cees

    2010-02-23

    In three experiments, using a two-alternative forced-choice task, we obtained depth judgments of displays containing transparent regions. The regions varied in lightness, size, and animation. Observers nearly always strongly preferred one certain depth ordering among the regions, even though their lightness conditions were expected to give rise to ambiguity among possible orderings. This expectation was based on the contrast polarity model, which expects ambiguity in the absence of contrast polarity reversal. The expectation was founded also on a stronger condition based on the transmittance anchoring principle, which gives preference to the largest lightness contrast between regions. In the absence of contrast polarity reversal and in conditions of balanced regional contrast, preferences were shown to depend on additional conditions of contrast between two respective regions and their overlap. Depth ordering judgment seems to be based on a critical decision threshold, independently of the coordinate system used to specify lightness. We also investigated the role of non-photometric factors such as motion and relative size, and concluded that these variables can modulate depth ordering judgments in transparency.

  20. Atmospheric diurnal and semi-diurnal variations observed with GPS radio occultation soundings

    Directory of Open Access Journals (Sweden)

    A. J. Mannucci

    2009-11-01

    Full Text Available Diurnal and semi-diurnal variations, driven by solar forcing, are two fundamental modes in the Earth's weather and climate system. Radio occultation (RO measurements from the six COSMIC satellites (Constellation Observing System for Meteorology Ionosphere and Climate provide rather uniform global coverage with high vertical resolution, all-weather and diurnal sampling capability. This paper analyzes the diurnal and semi-diurnal variations of both temperature and refractivity from two-year (2007–2008 COSMIC RO measurements in the troposphere and stratosphere. The RO observations reveal both propagating and trapped vertical structures of diurnal and semi-diurnal variations, including transition regions near the tropopause where data with high vertical resolution are critical. In the tropics the diurnal amplitude in refractivity decreases with altitude from a local maximum in the planetary boundary layer and reaches the minimum around 14 km and then further increase amplitude in the stratosphere. The upward propagating component of the migrating diurnal tides in the tropics is clearly captured by the GPS RO measurements, which show a downward progression in phase from upper troposphere to the stratopause with a vertical wavelength of about 25 km. Below 500 hPa (~5.5 km, seasonal variations of the peak diurnal amplitude in the tropics follow the solor forcing change in latitude, while at 30 km the seasonal pattern reverses with the diurnal amplitude peaking at the opposite side of the equator relative to the solar forcing. Polar regions shows large diurnal variations in the stratosphere with strong seasonal variations and the cause(s of these variations require further investigations.

  1. Diurnal variability of rainfall in southwest Amazonia during the LBA-TRMM field campaign of the austral summer of 1999 Variação diurna da chuva no sudoeste da Amazônia durante a campanha de campo do experimento LBA-TRMM no verão austral de 1999

    Directory of Open Access Journals (Sweden)

    José A. Marengo

    2004-12-01

    Full Text Available The TRMM-LBA field campaign was held during the austral summer of 1999 in southwestern Amazonia. Among the major objectives, was the identification and description of the diurnal variability of rainfall in the region, associated with the different rain producing weather systems that occurred during the January-February season. By using a network of 40 digital rain gauges implemented in the state of Rondônia, and together with observations and analyses of circulation and convection, it was possible to identify details of the diurnal cycle of rainfall and the associated rainfall mechanisms. Rainfall episodes were characterized by regimes of "low-level easterly" and "westerly" winds in the context of the large-scale circulation. The westerly regime is related to an enhanced South Atlantic Convergence Zone (SACZ and an intense and/or wide Low Level Jet (LLJ east of the Andes, which can extend eastward towards Rondônia, even though some westerly regime episodes also show a LLJ that remains close to the foothill of the Andes. The easterly regime is related to easterly propagating systems (e.g. squall-lines with possible weakened or less frequent LLJs and a suppressed SACZ. Diurnal variability of rainfall during westerly surface wind regime shows a characteristic maximum at late afternoon followed by a relatively weaker second maximum at early evening (2100 Local Standard Time LST. The easterly regime composite shows an early morning maximum followed by an even stronger maximum in the afternoon.O experimento de campo do TRMM-LBA ocorreu conteceu durante o verão austral de 1999, na região do sudeste de Amazonia. Entre os principais objetivos deste trabalho pode-se citar a identificação e descrição da variabilidade diurna da chuva nesta região, associada a diferentes fenômenos meteorológicos e sistemas de tempo que ocorreram durante o período de Janeiro-Fevereiro. Usando uma rede de 40 pluviômetros instalados no estado de Rond

  2. Diurnal variation of zooplankton off Versova (Bombay)

    Digital Repository Service at National Institute of Oceanography (India)

    Gajbhiye, S.N.; Nair, V.R.; Desai, B.N.

    Physicochemical parameters and diurnal variaion of zooplankton were studied off Versova on 17/18 February 1981. Salinity and dissolved oxygen showed limited variation during the period of study. Nutrient values followed the tidal rhythm and high...

  3. Diurnal and Seasonal Occurrence of Febrile Seizures

    Directory of Open Access Journals (Sweden)

    John J Millichap

    2015-04-01

    Full Text Available Investigators from University of Oulu, Finland, evaluated the diurnal and seasonal occurrence of the first febrile seizures (FS in 461 children in a population-based study of 1522 children.

  4. Photometric Redshifts of Galaxies in COSMOS

    CERN Document Server

    Mobasher, B; Scoville, N Z; Dahlen, T; Salvato, M; Aussel, H; Thompson, D J; Feldmann, R; Tasca, L; Lefèvre, O; Lilly, S; Carollo, C M; Kartaltepe, J S; McCracken, H; Mould, J; Renzini, A; Sanders, D B; Shopbell, P L; Taniguchi, Y; Ajiki, M; Shioya, Y; Contini, T; Giavalisco, M; Ilbert, O; Iovino, A; Le Brun, V; Mainieri, V; Mignoli, M; Scodeggio, M

    2006-01-01

    We measure photometric redshifts and spectral types for galaxies in the COSMOS survey. We use template fitting technique combined with luminosity function priors and with the option to simultaneously estimate dust extinction (i.e. E(B-V)) for each galaxy.Our estimated redshifts are accurate to i<25 and z~1.2. Using simulations with sampling and noise characteristics similar to those in COSMOS, the accuracy and reliability is estimated for the photometric redshifts as a function of the magnitude limits of the sample, S/N ratios and the number of bands used. From the simulations we find that the ratio of derived 95% confidence interval in the redshift probability distribution to the estimated photometric redshift (D95) can be used to identify and exclude the catastrophic failures in the photometric redshift estimates. We compare the derived redshifts with high-reliability spectroscopic redshifts for a sample of 868 normal galaxies with z < 1.2 from zCOSMOS. Considering different scenarios, depending on us...

  5. System for clinical photometric stereo endoscopy

    Science.gov (United States)

    Durr, Nicholas J.; González, Germán.; Lim, Daryl; Traverso, Giovanni; Nishioka, Norman S.; Vakoc, Benjamin J.; Parot, Vicente

    2014-02-01

    Photometric stereo endoscopy is a technique that captures information about the high-spatial-frequency topography of the field of view simultaneously with a conventional color image. Here we describe a system that will enable photometric stereo endoscopy to be clinically evaluated in the large intestine of human patients. The clinical photometric stereo endoscopy system consists of a commercial gastroscope, a commercial video processor, an image capturing and processing unit, custom synchronization electronics, white light LEDs, a set of four fibers with diffusing tips, and an alignment cap. The custom pieces that come into contact with the patient are composed of biocompatible materials that can be sterilized before use. The components can then be assembled in the endoscopy suite before use. The resulting endoscope has the same outer diameter as a conventional colonoscope (14 mm), plugs into a commercial video processor, captures topography and color images at 15 Hz, and displays the conventional color image to the gastroenterologist in real-time. We show that this system can capture a color and topographical video in a tubular colon phantom, demonstrating robustness to complex geometries and motion. The reported system is suitable for in vivo evaluation of photometric stereo endoscopy in the human large intestine.

  6. Application of Stochastic Modeling to Analysis of Photometric Reverberation Mapping Data

    Science.gov (United States)

    Zu, Ying; Kochanek, C. S.; Kozłowski, Szymon; Peterson, B. M.

    2016-03-01

    We use both simulated and real quasar light curves to explore modeling photometric reverberation-mapping (RM) data as a stochastic process. We do this using modifications to our previously developed RM method based on modeling quasar variability as a damped random walk. We consider the feasibility of one- and two-band photometric RM and compare the results with those from spectroscopic RM. We find that our method for two-band photometric RM can be competitive with spectroscopic RM only for strong (large equivalent width) lines like Hα and Hβ, and that the one-band method is also feasible but requires very high precision photometry. We fail to robustly detect Hα lags in single-band quasar light curves from OGLE-III and OGLE-IV despite the outstanding cadence and time span of the data, on account of photometric uncertainties in the range 0.02-0.04 mag. Simulations suggest that success could be achieved if the photometric uncertainties were of order 0.01 mag. Single-band RM for all lines and two-band RM for lower equivalent width lines are likely only feasible for statistical estimates of mean lags for large samples of active galactic nuclei of similar properties (e.g., luminosity) rather than for individual quasars. Our approach is directly applicable to the time-domain programs within ongoing and future wide-field imaging surveys and could provide robust lag measurements for an unprecedented number of systems.

  7. Surface diurnal warming in the East China Sea derived from satellite remote sensing

    Science.gov (United States)

    Song, Dan; Duan, Zhigang; Zhai, Fangguo; He, Qiqi

    2017-09-01

    Process of sea surface diurnal warming has drawn a lot of attention in recent years, but that occurs in shelf seas was rarely addressed. In the present work, surface diurnal warming strength in the East China Sea was calculated by the sea surface temperature (SST) data derived from the MODIS sensors carried by the satellites Aqua and Terra. Due to transit time difference, both the number of valid data and the surface diurnal warming strength computed by the MODIS-Aqua data are relatively larger than Terra. Therefore, the 10-year MODIS-Aqua data from 2005 to 2014 were used to analyze the monthly variability of the surface diurnal warming. Generally, the surface diurnal warming in the East China sea is stronger in summer and autumn but weaker in winter and spring, while it shows different peaks in different regions. Large events with ΔT≥5 K have also been discussed. They were found mainly in coastal area, especially near the Changjiang (Yangtze) River estuary. And there exists a high-incidence period from April to July. Furthermore, the relationship between surface diurnal warming and wind speed was discussed. Larger diurnal warming mainly lies in areas with low wind speed. And its possibility decreases with the increase of wind speed. Events with ΔT≥2.5 K rarely occur when wind speed is over 12 m/s. Study on surface diurnal warming in the East China Sea may help to understand the daily scale air-sea interaction in the shelf seas. A potential application might be in the marine weather forecasts by numerical models. Its impact on the coastal eco-system and the activities of marine organisms can also be pursued.

  8. On the realistic validation of photometric redshifts

    Science.gov (United States)

    Beck, R.; Lin, C.-A.; Ishida, E. E. O.; Gieseke, F.; de Souza, R. S.; Costa-Duarte, M. V.; Hattab, M. W.; Krone-Martins, A.

    2017-07-01

    Two of the main problems encountered in the development and accurate validation of photometric redshift (photo-z) techniques are the lack of spectroscopic coverage in the feature space (e.g. colours and magnitudes) and the mismatch between the photometric error distributions associated with the spectroscopic and photometric samples. Although these issues are well known, there is currently no standard benchmark allowing a quantitative analysis of their impact on the final photo-z estimation. In this work, we present two galaxy catalogues, Teddy and Happy, built to enable a more demanding and realistic test of photo-z methods. Using photometry from the Sloan Digital Sky Survey and spectroscopy from a collection of sources, we constructed data sets that mimic the biases between the underlying probability distribution of the real spectroscopic and photometric sample. We demonstrate the potential of these catalogues by submitting them to the scrutiny of different photo-z methods, including machine learning (ML) and template fitting approaches. Beyond the expected bad results from most ML algorithms for cases with missing coverage in the feature space, we were able to recognize the superiority of global models in the same situation and the general failure across all types of methods when incomplete coverage is convoluted with the presence of photometric errors - a data situation which photo-z methods were not trained to deal with up to now and which must be addressed by future large-scale surveys. Our catalogues represent the first controlled environment allowing a straightforward implementation of such tests. The data are publicly available within the COINtoolbox (https://github.com/COINtoolbox/photoz_catalogues).

  9. NZ Ser: the results of the analysis of the 25 years photometric activity

    Science.gov (United States)

    Barsunova, O.; Mel'nikov, S.; Grinin, V.; Katysheva, N.; Shugarov, S.

    2014-03-01

    We present the analysis of the long-term photometric variability of NZ Ser. The object shows both large-scale cyclic variability and low-amplitude Algol-like, fading typical for UX Ori stars. The variations of the stellar brightness are accompanied by variations of the B-V and V-R colors: when the brightness decreases, B-V decreases, while V-R increases.

  10. First Look at Photometric Reduction via Mixed-Model Regression (Poster abstract)

    Science.gov (United States)

    Dose, E.

    2016-12-01

    (Abstract only) Mixed-model regression is proposed as a new approach to photometric reduction, especially for variable-star photometry in several filters. Mixed-model regression adds to normal multivariate regression certain "random effects": categorical-variable terms that model and extract specific systematic errors such as image-to-image zero-point fluctuations (cirrus effect) or even errors in comp-star catalog magnitudes.

  11. Characterization of the bio-optical anomaly and diurnal variability of the particulate matter, as seen from the scattering and backscattering coefficients, in ultra-oligotrophic eddies of the Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    H. Loisel

    2011-08-01

    Full Text Available The variability of the inherent optical properties is investigated in the ultra-oligotrophic waters of the Mediterranean Sea sampled during the BOUM experiment performed during the early summer 2008. Bio-optical relationships found for the ultra-oligotrophic waters of the three anticyclonic gyres sampled significantly depart from the mean standard relationships provided for the global ocean, confirming the particular character of these Mediterranean waters. These optical anomalies are diversely related to the specific biological and environmental conditions occurring in the studied ecosystem. Specifically, the surface specific phytoplankton absorption coefficient exhibits values lower than those expected from the general relationships mainly in relation with a high contribution of relatively large sized phytoplankton. Conversely, the particulate backscattering coefficient, bbp, values are much higher than the mean standard values for a given chlorophyll-a concentration, TChl-a. This feature can presumably be related to the relevant influence of highly refractive submicrometer particles of Saharan origin in the surface layer of the water column. The present measurements also show that the Mediterranean Sea is greener than TChl-a alone indicates, as already stressed in previous studies. This color anomaly is partly explained by the estimated colored dissolved organic matter and submicrometer particles absorption coefficients, and to a greater extent by the high bbp/TChl-a values assuming that these particles backscatter light similarly in the green and blue parts of the visible spectrum. The diel variation of both the particulate matter attenuation and backscattering coefficients were also investigated specifically. Despite some differences in the timing and the magnitude of the daily oscillations found for these optical parameters, potential for the backscattering coefficient daily

  12. Measurement of photometric characteristics of daylighting systems

    Energy Technology Data Exchange (ETDEWEB)

    Aydinli, S.; Kaase, H. [Technical Univ., Berlin (Germany); Kischkoweit-Lopin, M. [Institut fuer Licht- und Bautechnik an der FH Koln, Cologne (Germany); Scartezzini, J. L.; Michel, L. [Ecole Poytechnuque Federale de Lausanne (Switzerland); Wienold, J.; Apian-Bennewitz, P. [Frauenhofer Institute for Solar Energy Systems, Freiburg (Germany)

    1998-09-01

    The photometric properties of daylighting systems determine the quality of the daylighting in the interior of a building, as well as the possible energy savings by the daylight responsive artificial lighting control systems. Photometric characteristics of daylighting systems and the principles of their measurements in laboratory facilities are described. Characteristics that depend on light incidence and observation of radiation can be measured using integrating sphere photometers or goniophotometers. Luminous transmittance measurements are usually carried out using integrating sphere photometers (cheaper and less time -consuming than measurements with a goniometer). Although the principles involved in the measurement are well understood, results frequently show certain deviations. The various errors that might be responsible for these deviations, whether attributable to the method, or the instrument, or the sample, are also discussed. 10 refs., 8 figs.

  13. A Photometric Search for Extrasolar Planets

    Science.gov (United States)

    Howell, S. B.; Everett, M.; Davis, D. R.; Weidenschilling, S. J.; McGruder, C. H., III; Gelderman, R.

    2000-10-01

    We describe a new program for the photometric detection of extrasolar planets using the 1.3 m telescope on Kitt Peak, which will be operated by a consortium of universities headed by Western Kentucky Univ. and including South Carolina State Univ., Planetary Science Institute, Boston Univ., and UC-Berkeley (SSL). This approach will complement the existing, highly successful, spectroscopic searches. The theory of photometric transit detection has been discussed by a number of authors (e.g. Borucki & Summers 1984; Howell & Merline 1995; Howell et al. 1996) and shown to be well within the capabilities of both photomultiplier and CCD observations. The first photometric transit detection was recently accomplished for the spectroscopically discovered planet orbiting HD209458 (Henry et al. 2000). The detection of extrasolar planet transits requires high photometric precision rather than accuracy. The necessary photometric precision to detect Jupiter-, Neptune-, and Earth-sized planets in orbit around F-M dwarfs is 1%, 0.1% and 0.00001%, respectively. The required precision to observe transits by Jupiter-sized extrasolar planets is easily obtained with modern CCD detectors and the differential ensemble photometric techniques pioneered by Howell et al. (1988). The use of such a technique for ultra-high precision photometry has been described in numerous papers (Charbonneau et al. 2000, Howell 2000, plus many others). Everett and Howell recently used the Kitt Peak NOAO 0.9 m telescope with the wide-field MOSAIC camera to search for extrasolar planet transits. During this run, they achieved a photometric precision of 0.024% for this dataset. With the 1.3 m telescope, we expect to reach a photometric precision of ~ 0.01% (10-4 mag). Our consortium has recently begun to refurbish and automate the 1.3 m telescope, which will be known as the Remote-Controlled Telescope (RCT). The primary instrument will be a CCD camera with a SITe 2048 x 2048 CCD having pixel well depths of 363

  14. Asteroid taxonomic signatures from photometric phase curves

    CERN Document Server

    Oszkiewicz, D A; Wasserman, L H; Muinonen, K; Penttilä, A; Pieniluoma, T; Trilling, D E; Thomas, C A

    2012-01-01

    We explore the correlation between an asteroid's taxonomy and photometric phase curve using the H, G12 photometric phase function, with the shape of the phase function described by the single parameter G12. We explore the usability of G12 in taxonomic classification for individual objects, asteroid families, and dynamical groups. We conclude that the mean values of G12 for the considered taxonomic complexes are statistically different, and also discuss the overall shape of the G12 distribution for each taxonomic complex. Based on the values of G12 for about half a million asteroids, we compute the probabilities of C, S, and X complex membership for each asteroid. For an individual asteroid, these probabilities are rather evenly distributed over all of the complexes, thus preventing meaningful classification. We then present and discuss the G12 distributions for asteroid families, and predict the taxonomic complex preponderance for asteroid families given the distribution of G12 in each family. For certain ast...

  15. Photometric Period of the Star PZ Mon

    Science.gov (United States)

    Antonyuk, K. A.; Bondar', N. I.; Pit', N. V.

    2017-09-01

    Results are presented from a search for periodic variations in the brightness and color indices of the active star PZ Mon based on many years of photometric data from 1992 to 2015. The photometric period derived from the entire set of observations is 34.16 days, but the period may vary by 1.5% within individual intervals. The color index V-R varies with the same period. These variations are indicative of reddening of the star with decreasing brightness. A correlation between the values exists over the entire observation interval. The variations in B-V occur over an interval of 26-28 days. A nonuniqueness in these variations shows up in a brightness-color index diagram: a reduction in the color index with decreasing brightness is observed in some epochs, which can be explained in terms of a spottedness model by the presence of cold, as well as hot, formations on the star's surface.

  16. Uncertain Photometric Redshifts with Deep Learning Methods

    Science.gov (United States)

    D'Isanto, A.

    2017-06-01

    The need for accurate photometric redshifts estimation is a topic that has fundamental importance in Astronomy, due to the necessity of efficiently obtaining redshift information without the need of spectroscopic analysis. We propose a method for determining accurate multi-modal photo-z probability density functions (PDFs) using Mixture Density Networks (MDN) and Deep Convolutional Networks (DCN). A comparison with a Random Forest (RF) is performed.

  17. A Blind Test of Hapke's Photometric Model

    Science.gov (United States)

    Helfenstein, P.; Shepard, M. K.

    2003-01-01

    Hapke's bidirectional reflectance equation is a versatile analytical tool for predicting (i.e. forward modeling) the photometric behavior of a particulate surface from the observed optical and structural properties of its constituents. Remote sensing applications of Hapke s model, however, generally seek to predict the optical and structural properties of particulate soil constituents from the observed photometric behavior of a planetary surface (i.e. inverse-modeling). Our confidence in the latter approach can be established only if we ruthlessly test and optimize it. Here, we summarize preliminary results from a blind-test of the Hapke model using laboratory measurements obtained with the Bloomsburg University Goniometer (B.U.G.). The first author selected eleven well-characterized powder samples and measured the spectrophotometric behavior of each. A subset of twenty undisclosed examples of the photometric measurement sets were sent to the second author who fit the data using the Hapke model and attempted to interpret their optical and mechanical properties from photometry alone.

  18. Photometric defocus observations of transiting extrasolar planets

    CERN Document Server

    Hinse, Tobias C; Yoon, Jo-Na; Lee, Chung-Uk; Kim, Yong-Gi; Kim, Chun-Hwey

    2015-01-01

    We have carried out photometric follow-up observations of bright transiting extrasolar planets using the CbNUOJ 0.6m telescope. We have tested the possibility of obtaining high photometric precision by applying the telescope defocus technique allowing the use of several hundred seconds in exposure time for a single measurement. We demonstrate that this technique is capable of obtaining a root-mean-square scatter of order sub-millimagnitude over several hours for a V $\\sim$ 10 host star typical for transiting planets detected from ground-based survey facilities. We compare our results with transit observations with the telescope operated in in-focus mode. High photometric precision is obtained due to the collection of a larger amount of photons resulting in a higher signal compared to other random and systematic noise sources. Accurate telescope tracking is likely to further contribute to lowering systematic noise by probing the same pixels on the CCD. Furthermore, a longer exposure time helps reducing the eff...

  19. Photometric redshifts in the SWIRE Survey

    CERN Document Server

    Rowan-Robinson, Michael; Oliver, Seb; Trichas, Markos; Berta, Stefano; Lonsdale, Carol; Smith, Gene; Shupe, David; Surace, Jason; Arnouts, Stephane; LeFevre, Olivier; Afonso-Luis, Alejandro; Perez-Fournon, Ismael; Hatziminaoglou, Evanthia; Polletta, Maria; Farrah, Duncan; Vaccari, Mattia

    2008-01-01

    We present the SWIRE Photometric Redshift Catalogue, 1024750 redshifts of unprecedented reliability and accuracy. Our method is based on fixed galaxy and QSO templates applied to data at 0.36-4.5 mu, and on a set of 4 infrared emission templates fitted to infrared excess data at 3.6-170 mu. The code involves two passes through the data, to try to optimize recognition of AGN dust tori. A few carefully justified priors are used and are the key to supression of outliers. Extinction, A_V, is allowed as a free parameter. We use a set of 5982 spectroscopic redshifts, taken from the literature and from our own spectroscopic surveys, to analyze the performance of our method as a function of the number of photometric bands used in the solution and the reduced chi^2. For 7 photometric bands the rms value of (z_{phot}-z_{spec})/(1+z_{spec}) is 3.5%, and the percentage of catastrophic outliers is ~1%. We discuss the redshift distributions at 3.6 and 24 mu. In individual fields, structure in the redshift distribution corr...

  20. Photometric Repeatability of Scanned Imagery: UVIS

    Science.gov (United States)

    Shanahan, Clare E.; McCullough, Peter; Baggett, Sylvia

    2017-08-01

    We provide the preliminary results of a study on the photometric repeatability of spatial scans of bright, isolated white dwarf stars with the UVIS channel of the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST). We analyze straight-line scans from the first pair of identical orbits of HST program 14878 to assess if sub 0.1% repeatability can be attained with WFC3/UVIS. This study is motivated by the desire to achieve better signal-to-noise in the UVIS contamination and stability monitor, in which observations of standard stars in staring mode have been taken from the installation of WFC3 in 2009 to the present to assess temporal photometric stability. Higher signal to noise in this program would greatly benefit the sensitivity to detect contamination, and to better characterize the observed small throughput drifts over time. We find excellent repeatability between identical visits of program 14878, with sub 0.1% repeatability achieved in most filters. These! results support the initiative to transition the staring mode UVIS contamination and photometric stability monitor from staring mode images to spatial scans.

  1. A MACHINE-LEARNING METHOD TO INFER FUNDAMENTAL STELLAR PARAMETERS FROM PHOTOMETRIC LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Miller, A. A. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, MS 169-506, Pasadena, CA 91109 (United States); Bloom, J. S.; Richards, J. W.; Starr, D. L. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Lee, Y. S. [Department of Astronomy and Space Science, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Butler, N. R. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85281 (United States); Tokarz, S. [Smithsonian Astrophysical Observatory, Cambridge, MA 02138 (United States); Smith, N.; Eisner, J. A., E-mail: amiller@astro.caltech.edu [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)

    2015-01-10

    A fundamental challenge for wide-field imaging surveys is obtaining follow-up spectroscopic observations: there are >10{sup 9} photometrically cataloged sources, yet modern spectroscopic surveys are limited to ∼few× 10{sup 6} targets. As we approach the Large Synoptic Survey Telescope era, new algorithmic solutions are required to cope with the data deluge. Here we report the development of a machine-learning framework capable of inferring fundamental stellar parameters (T {sub eff}, log g, and [Fe/H]) using photometric-brightness variations and color alone. A training set is constructed from a systematic spectroscopic survey of variables with Hectospec/Multi-Mirror Telescope. In sum, the training set includes ∼9000 spectra, for which stellar parameters are measured using the SEGUE Stellar Parameters Pipeline (SSPP). We employed the random forest algorithm to perform a non-parametric regression that predicts T {sub eff}, log g, and [Fe/H] from photometric time-domain observations. Our final optimized model produces a cross-validated rms error (RMSE) of 165 K, 0.39 dex, and 0.33 dex for T {sub eff}, log g, and [Fe/H], respectively. Examining the subset of sources for which the SSPP measurements are most reliable, the RMSE reduces to 125 K, 0.37 dex, and 0.27 dex, respectively, comparable to what is achievable via low-resolution spectroscopy. For variable stars this represents a ≈12%-20% improvement in RMSE relative to models trained with single-epoch photometric colors. As an application of our method, we estimate stellar parameters for ∼54,000 known variables. We argue that this method may convert photometric time-domain surveys into pseudo-spectrographic engines, enabling the construction of extremely detailed maps of the Milky Way, its structure, and history.

  2. ANALYSIS THE DIURNAL VARIATIONS ON SELECTED PHYSICAL AND PHYSIOLOGICAL PARAMETERS

    Directory of Open Access Journals (Sweden)

    A. MAHABOOBJAN

    2010-12-01

    Full Text Available The purpose of the study was to analyze the diurnal variations on selected physical and physiological parameters such as speed, explosive power, resting heart rate and breath holding time among college students. To achieve the purpose of this study, a total of twenty players (n=20 from Government Arts College, Salem were selected as subjects To study the diurnal variation of the players on selected physiological and performance variables, the data were collected 4 times a day with every four hours in between the times it from 6.00 to 18.00 hours were selected as another categorical variable. One way repeated measures (ANOVA was used to analyze the data. If the obtained F-ratio was significant, Seheffe’s post-hoc test was used to find out the significant difference if anyamong the paired means. The level of significance was fixed at.05 level. It has concluded that both physical and physiological parameters were significantly deferred with reference to change of temperature in a day

  3. Emotional attentional control predicts changes in diurnal cortisol secretion following exposure to a prolonged psychosocial stressor

    OpenAIRE

    Lenaert, Bert; Barry, Tom; Schruers, Koen; Vervliet, Bram; Hermans, Dirk

    2015-01-01

    Hypothalamic-pituitary-adrenal (HPA) axis irregularities have been associated with several psychological disorders. Hence, the identification of individual difference variables that predict variations in HPA-axis activity represents an important challenge for psychiatric research. We investigated whether self-reported attentional control in emotionally demanding situations prospectively predicted changes in diurnal salivary cortisol secretion following exposure to a prolonged psychosocial str...

  4. A Combined Infrared and Microwave Technique for Studying the Diurnal Variation of Rainfall Over Amazonia

    Science.gov (United States)

    Negri, Andrew J.; Xu, L.; Adler, R. F.; Anagnostou, E.; Rickenbach, T. M.

    1999-01-01

    In this paper we present results from the application of a satellite infrared (IR) technique for estimating rainfall over northern South America. Our main objectives are to examine the diurnal variability of rainfall and to investigate the relative contributions from the convective and stratiform components. Additional information is contained in the original.

  5. A photometric study of the close binary Delta Orionis A

    Science.gov (United States)

    Koch, R. H.; Hrivnak, B. J.

    1981-08-01

    Green and blue photoelectric light curves show the historical intrinsic variability of the Delta Ori A close binary superposed on the interaction and eclipse effects. There is a considerable measure of agreement between spectrographic and photometric determinations of the rate of apsidal advance. The determinacy of orbital eccentricity, however, is confused because few minima of indifferent precision exist to check the spectrographic value. No physical mechanism can be found to account for a possible diminution of orbital eccentricity, and this is probably best attributed to unrecognized complications of at least one of the existing light curves. After numerous trials, a less-than-perfect theoretical representation of the light curve was achieved and shows the system to be detached. The absolute stellar parameters make clear that both components have evolved substantially. A mean stellar structure constant k2 is derived but cannot be compared usefully to existing theoretical values. The importance of the recently discovered visual companion, hz 42, is emphasized.

  6. The first decade of RR Lyrae space photometric observations

    CERN Document Server

    Molnár, Lászlo

    2016-01-01

    Space-based photometric telescopes stirred up stellar astrophysics in the last decade, and RR Lyrae stars have not been an exception from that either. The long, quasi-continuous, high-precision data from MOST, CoRoT and Kepler revealed a wealth of new insights about this well-known variable class. One of the most surprising mysteries turned out to be the apparent omnipresence of a common additional mode in all RRd and RRc stars. Moreover, fundamental-mode stars seem to populate two distinct classes, one of which is characterized by the presence of additional modes and/or modulation, and another limited to strict single-mode pulsation. The presence of additional modes and multiple modulations in RRab stars allowed us to construct Petersen diagrams for these parameters: while the pulsation modes show clear structures according to period ratios, there seems to be no relation between the modulation periods themselves.

  7. DES Science Portal: Computing Photometric Redshifts

    Energy Technology Data Exchange (ETDEWEB)

    Gschwend, Julia [LIneA, Rio de Janeiro

    2016-01-01

    An important challenge facing photometric surveys for cosmological purposes, such as the Dark Energy Survey (DES), is the need to produce reliable photometric redshifts (photo-z). The choice of adequate algorithms and configurations and the maintenance of an up-to-date spectroscopic database to build training sets, for example, are challenging tasks when dealing with large amounts of data that are regularly updated and constantly growing. In this paper, we present the first of a series of tools developed by DES, provided as part of the DES Science Portal, an integrated web-based data portal developed to facilitate the scientific analysis of the data, while ensuring the reproducibility of the analysis. We present the DES Science Portal photometric redshift tools, starting from the creation of a spectroscopic sample to training the neural network photo-z codes, to the final estimation of photo-zs for a large photometric catalog. We illustrate this operation by calculating well calibrated photo-zs for a galaxy sample extracted from the DES first year (Y1A1) data. The series of processes mentioned above is run entirely within the Portal environment, which automatically produces validation metrics, and maintains the provenance between the different steps. This system allows us to fine tune the many steps involved in the process of calculating photo-zs, making sure that we do not lose the information on the configurations and inputs of the previous processes. By matching the DES Y1A1 photometry to a spectroscopic sample, we define different training sets that we use to feed the photo-z algorithms already installed at the Portal. Finally, we validate the results under several conditions, including the case of a sample limited to i<22.5 with the color properties close to the full DES Y1A1 photometric data. This way we compare the performance of multiple methods and training configurations. The infrastructure presented here is an effcient way to test several methods of

  8. Cone photopigments in nocturnal and diurnal procyonids.

    Science.gov (United States)

    Jacobs, G H; Deegan, J F

    1992-10-01

    Procyonids are small, New World carnivores distributed among some 6 genera. Electroretinogram (ERG) flicker photometry was used to measure the spectra of the cone photopigments for members of two nocturnal species, the raccoon (Procyon lotor) and the kinkajou (Potos flavus), and a diurnal species, the coati (Nasua nasua). Each of the 3 has a class of cone photopigment with maximum sensitivity in the middle to long wavelengths. The spectral positioning of this cone is different for the three. Whereas the raccoon and kinkajou are monochromatic, the diurnal coati is a dichromat having an additional class of cone photopigment with peak sensitivity close to 433 nm.

  9. DETECTION OF KOI-13.01 USING THE PHOTOMETRIC ORBIT

    Energy Technology Data Exchange (ETDEWEB)

    Shporer, Avi [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Santa Barbara, CA 93117 (United States); Jenkins, Jon M.; Seader, Shawn E.; Smith, Jeffrey C.; Thompson, Susan E.; Twicken, Joseph D. [SETI Institute/NASA Ames Research Center, Moffett Field, CA 94035 (United States); Rowe, Jason F.; Sanderfer, Dwight T. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Still, Martin D. [Bay Area Environmental Research Institute/NASA Ames Research Center, Moffett Field, CA 94035 (United States); Welsh, William F., E-mail: ashporer@lcogt.net [Astronomy Department, San Diego State University, San Diego, CA 92182 (United States)

    2011-12-15

    We use the KOI-13 transiting star-planet system as a test case for the recently developed BEER algorithm, aimed at identifying non-transiting low-mass companions by detecting the photometric variability induced by the companion along its orbit. Such photometric variability is generated by three mechanisms: the beaming effect, tidal ellipsoidal distortion, and reflection/heating. We use data from three Kepler quarters, from the first year of the mission, while ignoring measurements within the transit and occultation, and show that the planet's ephemeris is clearly detected. We fit for the amplitude of each of the three effects and use the beaming effect amplitude to estimate the planet's minimum mass, which results in M{sub p} sin i = 9.2 {+-} 1.1 M{sub J} (assuming the host star parameters derived by Szabo et al.). Our results show that non-transiting star-planet systems similar to KOI-13.01 can be detected in Kepler data, including a measurement of the orbital ephemeris and the planet's minimum mass. Moreover, we derive a realistic estimate of the amplitudes uncertainties, and use it to show that data obtained during the entire lifetime of the Kepler mission of 3.5 years will allow detecting non-transiting close-in low-mass companions orbiting bright stars, down to the few Jupiter mass level. Data from the Kepler Extended Mission, if funded by NASA, will further improve the detection capabilities.

  10. Modelling the diurnal variability of SST and its vertical extent

    DEFF Research Database (Denmark)

    Karagali, Ioanna; Høyer, Jacob L.; Donlon, Craig J.

    2014-01-01

    for the transport of heat, momentum and salt. GOTM is a model resolving the basic hydrodynamic and thermodynamic processes related to vertical mixing in the water column, that includes most of the basic methods for calculating the turbulent fluxes. Surface heat and momentum can be either calculated or externally...... of the modelled output with observations. To improve the surface heat budget calculation and distribution of heat in the water column, the GOTM code was modified to include an additional method for the estimation of the total outgoing long-wave radiation and a 9-band parametrisation for the light extinction...... between in situ and remotely obtained measurements, is through modelling of the upper ocean temperature. Models that have been used for this purpose vary from empirical parametrisations mostly based on the wind speed and solar insolation to ocean models that solve the 1 dimensional equations...

  11. Diurnal variability of Synechococcus abundance in Sagami Bay, Japan

    Digital Repository Service at National Institute of Oceanography (India)

    Mitbavkar, S.; Saino, T.

    light-dark cycle. Journal of Phycology 15: 67-75. Parsons, T.R., Y. Maita & C.M. Lalli, 1984. A manual of chemical and biological seawater analysis. Pergamon, New York. Partensky, F., W.R. Hess & D. Vaulot, 1999. Prochlorococcus, a marine...

  12. Diurnal variations in the UV albedo of arctic snow

    Directory of Open Access Journals (Sweden)

    O. Meinander

    2008-11-01

    Full Text Available The relevance of snow for climate studies is based on its physical properties, such as high surface reflectivity. Surface ultraviolet (UV albedo is an essential parameter for various applications based on radiative transfer modeling. Here, new continuous measurements of the local UV albedo of natural Arctic snow were made at Sodankylä (67°22'N, 26°39'E, 179 m a.s.l. during the spring of 2007. The data were logged at 1-min intervals. The accumulation of snow was up to 68 cm. The surface layer thickness varied from 0.5 to 35 cm with the snow grain size between 0.2 and 2.5 mm. The midday erythemally weighted UV albedo ranged from 0.6 to 0.8 in the accumulation period, and from 0.5 to 0.7 during melting. During the snow melt period, under cases of an almost clear sky and variable cloudiness, an unexpected diurnal decrease of 0.05 in albedo soon after midday, and recovery thereafter, was detected. This diurnal decrease in albedo was found to be asymmetric with respect to solar midday, thus indicating a change in the properties of the snow. Independent UV albedo results with two different types of instruments confirm these findings. The measured temperature of the snow surface was below 0°C on the following mornings. Hence, the reversible diurnal change, evident for ~1–2 h, could be explained by the daily metamorphosis of the surface of the snowpack, in which the temperature of the surface increases, melting some of the snow to liquid water, after which the surface freezes again.

  13. Chronobiology of chronic pain: focus on diurnal rhythmicity of neuropathic pain.

    Science.gov (United States)

    Gilron, Ian; Ghasemlou, Nader

    2014-12-01

    Although circadian rhythmicity has long been recognized in various nociceptive pain conditions such as arthritis, diurnal pain patterns in neuropathic conditions have only recently been described. The purpose of this article is to review emerging evidence and discuss future research to further understand this phenomenon. Secondary analyses of neuropathic pain clinical trials demonstrate that pain intensity fluctuations exhibit a distinct diurnal pattern that contrasts that of nociceptive pain conditions. Ongoing preclinical investigations support the phenomenon of circadian pain fluctuations and provide the opportunity to better describe pain chronobiology and to elucidate underlying mechanisms of circadian pain rhythmicity. The observation of clinically relevant diurnal pain variability in neuropathic conditions has important implications for future research and treatment of pain. This is an immature research field, and further investigation is needed to better characterize these patterns in more detail, investigate contributory mechanisms, and to develop therapeutic strategies that exploit this phenomenon.

  14. Diurnally entrained anticipatory behavior in archaea.

    Directory of Open Access Journals (Sweden)

    Kenia Whitehead

    Full Text Available By sensing changes in one or few environmental factors biological systems can anticipate future changes in multiple factors over a wide range of time scales (daily to seasonal. This anticipatory behavior is important to the fitness of diverse species, and in context of the diurnal cycle it is overall typical of eukaryotes and some photoautotrophic bacteria but is yet to be observed in archaea. Here, we report the first observation of light-dark (LD-entrained diurnal oscillatory transcription in up to 12% of all genes of a halophilic archaeon Halobacterium salinarum NRC-1. Significantly, the diurnally entrained transcription was observed under constant darkness after removal of the LD stimulus (free-running rhythms. The memory of diurnal entrainment was also associated with the synchronization of oxic and anoxic physiologies to the LD cycle. Our results suggest that under nutrient limited conditions halophilic archaea take advantage of the causal influence of sunlight (via temperature on O(2 diffusivity in a closed hypersaline environment to streamline their physiology and operate oxically during nighttime and anoxically during daytime.

  15. Robust fitting of diurnal brightness temperature cycle

    CSIR Research Space (South Africa)

    Udahemuka, G

    2007-11-01

    Full Text Available for a pixel concerned. Robust fitting of observed Diurnal Temperature Cycle (DTC) taken over a day of a given pixel without cloud cover and other abnormally conditions such as fire can give a data based brightness temperature model for a given pixel...

  16. Scale interactions on diurnal toseasonal timescales and their relevanceto model systematic errors

    Directory of Open Access Journals (Sweden)

    G. Yang

    2003-06-01

    Full Text Available Examples of current research into systematic errors in climate models are used to demonstrate the importance of scale interactions on diurnal,intraseasonal and seasonal timescales for the mean and variability of the tropical climate system. It has enabled some conclusions to be drawn about possible processes that may need to be represented, and some recommendations to be made regarding model improvements. It has been shown that the Maritime Continent heat source is a major driver of the global circulation but yet is poorly represented in GCMs. A new climatology of the diurnal cycle has been used to provide compelling evidence of important land-sea breeze and gravity wave effects, which may play a crucial role in the heat and moisture budget of this key region for the tropical and global circulation. The role of the diurnal cycle has also been emphasized for intraseasonal variability associated with the Madden Julian Oscillation (MJO. It is suggested that the diurnal cycle in Sea Surface Temperature (SST during the suppressed phase of the MJO leads to a triggering of cumulus congestus clouds, which serve to moisten the free troposphere and hence precondition the atmosphere for the next active phase. It has been further shown that coupling between the ocean and atmosphere on intraseasonal timescales leads to a more realistic simulation of the MJO. These results stress the need for models to be able to simulate firstly, the observed tri-modal distribution of convection, and secondly, the coupling between the ocean and atmosphere on diurnal to intraseasonal timescales. It is argued, however, that the current representation of the ocean mixed layer in coupled models is not adequate to represent the complex structure of the observed mixed layer, in particular the formation of salinity barrier layers which can potentially provide much stronger local coupling between the atmosphere and ocean on diurnal to intraseasonal timescales.

  17. Changes in the Diurnal Cycles of Precipitation over Eastern China in the Past 40 Years

    Institute of Scientific and Technical Information of China (English)

    YUAN Weihua; YU Rucong; LI Jian

    2013-01-01

    This study analyzed the interdecadal changes in the diurnal variability of summer (June August) precipitation over eastern China during the period 1966 2005 using hourly station rain gauge data.The results revealed that rainfall diurnal variations experienced significant interdecadal changes.Over the area to the south of the Yangtze River,as well as the area between the Yangtze and Yellow Rivers,the percentages of morning rainfall (0000-1200 LST) to total rainfall in terms of amount,frequency and intensity,all exhibited increasing interdecadal trends.On the contrary,over North China,decreasing trends were found.As a result,diurnal rainfall peaks also presented pronounced interdecadal variations.Over the area between the Yangtze and Yellow Rivers,there were 16 out of 46 stations with afternoon (1200 0000 LST) frequency peaks in the first 20 years of the 40-year period of study,while only eight remained in the latter 20 years.In North China,seven stations experienced the opposite changes,which accounted for about 21% of the total number of stations.The possible causes for the interdecadal changes in diurnal features were discussed.As the rainfall in the active monsoon period presents morning diurnal peaks,with afternoon peaks in the break period,the decrease (increase) of rainfall in the active monsoon period over North China (the area south of the Yangtze River and the area between the Yangtze and Yellow Rivers) may contribute to interdecadal changes in diurnal rainfall variability.

  18. Impact of assimilation window length on diurnal features in a Mars atmospheric analysis

    Directory of Open Access Journals (Sweden)

    Yongjing Zhao

    2015-05-01

    Full Text Available Effective simulation of diurnal variability is an important aspect of many geophysical data assimilation systems. For the Martian atmosphere, thermal tides are particularly prominent and contribute much to the Martian atmospheric circulation, dynamics and dust transport. To study the Mars diurnal variability and Mars thermal tides, the Geophysical Fluid Dynamics Laboratory Mars Global Climate Model with the 4D-local ensemble transform Kalman filter (4D-LETKF is used to perform an analysis assimilating spacecraft temperature retrievals. We find that the use of a ‘traditional’ 6-hr assimilation cycle induces spurious forcing of a resonantly enhanced semi-diurnal Kelvin waves represented in both surface pressure and mid-level temperature by forming a wave 4 pattern in the diurnal averaged analysis increment that acts as a ‘topographic’ stationary forcing. Different assimilation window lengths in the 4D-LETKF are introduced to remove the artificially induced resonance. It is found that short assimilation window lengths not only remove the spurious resonance, but also push the migrating semi-diurnal temperature variation at 50 Pa closer to the estimated ‘true’ tides even in the absence of a radiatively active water ice cloud parameterisation. In order to compare the performance of different assimilation window lengths, short-term to mid-range forecasts based on the hour 00 and 12 assimilation are evaluated and compared. Results show that during Northern Hemisphere summer, it is not the assimilation window length, but the radiatively active water ice clouds that influence the model prediction. A ‘diurnal bias correction’ that includes bias correction fields dependent on the local time is shown to effectively reduce the forecast root mean square differences between forecasts and observations, compensate for the absence of water ice cloud parameterisation and enhance Martian atmosphere prediction. The implications of these results for

  19. Photometric Redshifts for the SDSS Early Data Release

    CERN Document Server

    Csabai, I; Connolly, A J; Szalay, A S; Györy, Z; Benítez, N; Annis, J; Brinkmann, J; Eisenstein, D J; Fukugita, M; Gunn, J; Kent, S; Lupton, R; Nichol, R C; Stoughton, C; Csabai, Istvan; Budavari, Tamas; Connolly, Andrew J.; Szalay, Alexander S.; Gyory, Zsuzsanna; Benitez, Narciso; Annis, Jim; Brinkmann, Jon; Eisenstein, Daniel; Fukugita, Masataka; Gunn, Jim; Kent, Stephen; Lupton, Robert; Nichol, Robert C.; Stoughton, Chris

    2003-01-01

    The Early Data Release from the Sloan Digital Sky survey provides one of the largest multicolor photometric catalogs currently available to the astronomical community. In this paper we present the first application of photometric redshifts to the $\\sim 6$ million extended sources within these data (with 1.8 million sources having $r' < 21$). Utilizing a range of photometric redshift techniques, from empirical to template and hybrid techniques, we investigate the statistical and systematic uncertainties present within the redshift estimates for the EDR data. For $r'<21$ we find that the redshift estimates provide realistic redshift histograms with an rms uncertainty in the photometric redshift relation of 0.035 at $r'<18$ and rising to 0.1 at $r'<21$. We conclude by describing how these photometric redshifts and derived quantities, such as spectral type, restframe colors and absolute magnitudes, are stored within the SDSS database. We provide sample queries for searching on photometric redshifts an...

  20. Photometric Solutions of Some Contact ASAS Binaries

    CERN Document Server

    Gezer, I

    2015-01-01

    We present the first light curve solution of 6 contact binary systems which are chosen from the ASAS catalog. The photometric elements and the estimated absolute parameters of all systems are obtained with the light curve analyses. We calculated the values of degree of contact for the systems. The location of the targets on the Hertzsprung-Russell diagram and the mass-radius plane is compared to the other well-known contact binaries and the evolutionary status of the systems are also discussed.

  1. Photometric solutions of some contact ASAS binaries

    Science.gov (United States)

    Gezer, İ.; Bozkurt, Z.

    2016-04-01

    We present the first light curve solution of 6 contact binary systems which are chosen from the ASAS catalog. The photometric elements and the estimated absolute parameters of all systems are obtained with the light curve analyses. We calculated the values of degree of contact for the systems. The location of the targets on the Hertzsprung-Russell diagram and the mass-radius plane is compared to the other well-known contact binaries and the evolutionary status of the systems are also discussed.

  2. Hyperspectral photometric stereo for a single capture.

    Science.gov (United States)

    Ozawa, Keisuke; Sato, Imari; Yamaguchi, Masahiro

    2017-03-01

    We present a single-capture photometric stereo method using a hyperspectral camera. A spectrally and spatially designed illumination enables a point-wise estimation of reflectance spectra and surface normals from a single hyperspectral image. The illumination works as a reflectance probe in wide spectral regions where reflectance spectra are measured, and the full spectra are estimated by interpolation. It also works as the resource for shadings in other spectral regions. The accuracy of estimation is evaluated in a simulation. Also, we prepare an experimental setup and demonstrate a surface reconstruction against a real scene.

  3. Difficult cases in photometric studies of asteroids

    Science.gov (United States)

    Marciniak, Anna; Pilcher, Frederick; Oszkiewicz, Dagmara; Bartczak, Przemysław; Santana-Ros, Toni; Kamiński, Krzysztof; Urakawa, Seitaro; Ogłoza, Waldemar; Fauvaud, Stéphane; Kankiewicz, Paweł; Kudak, Viktor; Żejmo, Michał; Nishiyama, Kota; Okumura, Shin-ichiro; Nimura, Tokuhiro; Hirsch, Roman; Konstanciak, Izabella; Tychoniec, Łukasz; Figas, Michał

    2016-06-01

    We present a photometric campaign targeted at asteroids that display both long periods of rotation and small amplitudes of brightness variations. Our aim is to debias available sample of spin and shape modelled asteroids and to correct previous wrong period determinations. Our newest findings are corrected period determinations for asteroids (279) Thule (P=23.896h ± 0.005 h), (673) Edda (P=22.340h ± 0.004 h), and (737) Arequipa (P=7.0259h ± 0.0003 h). Supporting lightcurves are presented in this paper.

  4. Application of the Trend Filtering Algorithm for Photometric Time Series Data

    CERN Document Server

    Gopalan, Giri; van Eyken, Julian; Ciardi, David; von Braun, Kaspar; Kane, Stephen R

    2016-01-01

    Detecting transient light curves (e.g., transiting planets) requires high precision data, and thus it is important to effectively filter systematic trends affecting ground based wide field surveys. We apply an implementation of the Trend Filtering Algorithm (TFA) (Kovacs et al. 2005) to the 2MASS calibration catalog and select Palomar Transient Factory (PTF) photometric time series data. TFA is successful at reducing the overall dispersion of light curves, however it may over filter intrinsic variables and increase "instantaneous" dispersion when a template set is not judiciously chosen. In an attempt to rectify these issues we modify the original literature TFA by including measurement uncertainties in its computation, including ancillary data correlated with noise, and algorithmically selecting a template set using clustering algorithms as suggested by various authors. This approach may be particularly useful for appropriately accounting for variable photometric precision surveys and/or combined data-sets. ...

  5. Southern near-infrared photometric monitoring of Galactic young star clusters (NIP of Stars)

    CERN Document Server

    Barbá, R; Gunthardt, G; Robledo, S Torres; Jaque, M; Soto, M; Ferrero, G; Arias, J; Román-Lópes, A; Gamen, R; Hormazabal, J Astudillo

    2012-01-01

    We have performed a near-infrared photometric monitoring of 39 galactic young star clusters and star-forming regions, known as {\\em NIP of Stars}, between the years 2009--2011, using the Swope telescope at Las Campanas Observatory (Chile) and the RetroCam camera. The primary objective of the campaign is to perform a census of photometric variability of such clusters and to discover massive eclipsing binary stars. In this work, we describe the general idea, the implementation of the survey, and the first preliminary results of some of the observed clusters. This monitoring program is complementary to the Vista Variables in the V\\'ia L\\'actea (VVV), as the brightest sources observed in NIP of Stars are saturated in VVV.

  6. Southern near-infrared photometric monitoring of Galactic young star clusters (NIP of Stars)

    Science.gov (United States)

    Barbá, R.; Morrell, N. I.; Gunthardt, G.; Torres Robledo, S.; Jaque, M.; Soto, M.; Ferrero, G.; Arias, J. I.; Roman-Lopes, A.; Gamen, R. C.; Astudillo Hormazabal, J.

    We have performed a near-infrared photometric monitoring of 39 galactic young star clusters and star-forming regions, known as NIP of Stars, be- tween the years 2009-2011, using the Swope telescope at Las Campanas Observatory (Chile) and the RetroCam camera. The primary objective of the campaign is to perform a census of photometric variability of such clus- ters and to discover massive eclipsing binary stars. In this work, we describe the general idea, the implementation of the survey, and the first preliminary results of some of the observed clusters. This monitoring program is com- plementary to the Vista Variables in the Vía Láctea (VVV), as the brightest sources observed in NIP of Stars are saturated in VVV.

  7. Photometric study of the eclipsing binary ET Psc

    Science.gov (United States)

    Özalp, G. Z.; Özkardeş, B.

    2016-03-01

    We present the photometric solution of the eclipsing binary ET Psc (GSC 00608-00490). The ASAS V-band photometric data of the system was modelled using the Wilson-Devinney method. The result shows that the eclipsing pair could be classified as A-subtype of W UMa-type binary system. The absolute dimensions of the system were also estimated based on the photometric solution.

  8. Diurnal cycles in water quality across the periodic table

    Science.gov (United States)

    Kirchner, James

    2014-05-01

    Diurnal cycles in water quality can provide important clues to the processes that regulate aquatic chemistry, but they often are masked by longer-term, larger-amplitude variability, making their detection and quantification difficult. Here I outline methods that can detect diurnal cycles even when they are massively obscured by statistically ill-behaved noise. I demonstrate these methods using high-frequency water quality data from the Plylimon catchment in mid-Wales (Neal et al., 2013; Kirchner and Neal, 2013). Several aspects combine to make the Plynlimon data set unique worldwide. Collected at 7-hour intervals, the Plynlimon data set is much more densely sampled than typical long-term weekly or monthly water quality data. This 7-hour sampling was also continued for two years, much longer than typical intensive sampling campaigns, and the resulting time series encompass a wide range of climatic and hydrological conditions. Furthermore, each sample was analyzed for a wide range of solutes with diverse sources in the natural environment. However, the 7-hour sampling frequency is both coarse and irregular in comparison to diurnal cycles, making their detection and quantification difficult. Nonetheless, the methods outlined here enable detection of statistically significant diurnal cycles in over 30 solutes at Plynlimon, including alkali metals (Li, Na, K, Rb, and Cs), alkaline earths (Be, Mg, Ca, Sr, and Ba), transition metals (Al, Ti, Mn, Fe, Co, Ni, Zn, Mo, Cd, and Pb), nonmetals (B, NO3, Si, As, and Se), lanthanides and actinides (La, Ce, Pr, and U), as well as total dissolved nitrogen (TDN), dissolved organic carbon (DOC), Gran alkalinity, pH, and electrical conductivity. These solutes span every row of the periodic table, and more than six orders of magnitude in concentration. Many of these diurnal cycles are subtle, representing only a few percent, at most, of the total variance in the concentration time series. Nonetheless they are diagnostically useful

  9. Deep learning over diurnal and other environmental effects

    Science.gov (United States)

    Rosario, Dalton; Rauss, Patrick

    2017-05-01

    We study the transfer learning behavior of a Hybrid Deep Network (HDN) applied to a challenging longwave infrared hyperspectral dataset, consisting of radiance from several manmade and natural materials within a fixed site located 500 m from an observation tower, over multiple full diurnal cycles and different atmospheric conditions. The HDN architecture adopted in this study stakes a number of Restricted Boltzmann Machines to form a deep belief network for generative pre-training, or initialization of weight parameters, and then combines with a discriminative learning procedure that fine-tune all of the weights jointly to improve the network's performance. After fine-tuning, a network with three hidden layers forms a very good generative model of the joint distribution of spectral data and their labels, despite of significant data variability observed between and within classes due to environmental and temperature variation, occurring within full diurnal cycles. We argue, however, that more question are raised than answers are provided regarding the generalization capacity of these deep nets through experiments aimed for investigating their training and transfer learning behavior in the longwave infrared region of the electromagnetic spectrum.

  10. Long-term photometric behavior of the PMS stars V977 Cep and V982 Cep in the vicinity of NGC 7129

    CERN Document Server

    Ibryamov, Sunay I; Milanov, Teodor R; Peneva, Stoyanka P

    2016-01-01

    Long-term BVRI photometric light curves of the pre-main sequence stars V977 Cep and V982 Cep during the period from 2000 October to 2016 August are presented. The stars are located in the vicinity of the reflection nebula NGC 7129. Our photometric data shows that both stars exhibit strong photometric variability in all optical passbands, which is typical for Classical T Tauri stars. Using our observational data we defined the reasons for the observed brightness variations. In the case of V977 Cep we registered previously unknown periodicity in its light curve.

  11. Asteroid models from the Lowell Photometric Database

    CERN Document Server

    Durech, J; Oszkiewicz, D; Vanco, R

    2016-01-01

    We use the lightcurve inversion method to derive new shape models and spin states of asteroids from the sparse-in-time photometry compiled in the Lowell Photometric Database. To speed up the time-consuming process of scanning the period parameter space through the use of convex shape models, we use the distributed computing project Asteroids@home, running on the Berkeley Open Infrastructure for Network Computing (BOINC) platform. This way, the period-search interval is divided into hundreds of smaller intervals. These intervals are scanned separately by different volunteers and then joined together. We also use an alternative, faster, approach when searching the best-fit period by using a model of triaxial ellipsoid. By this, we can independently confirm periods found with convex models and also find rotation periods for some of those asteroids for which the convex-model approach gives too many solutions. From the analysis of Lowell photometric data of the first 100,000 numbered asteroids, we derived 328 new ...

  12. Photometric Redshift Estimation Using Spectral Connectivity Analysis

    CERN Document Server

    Freeman, P E; Lee, A B; Richards, J W; Schafer, C M

    2009-01-01

    The development of fast and accurate methods of photometric redshift estimation is a vital step towards being able to fully utilize the data of next-generation surveys within precision cosmology. In this paper we apply a specific approach to spectral connectivity analysis (SCA; Lee & Wasserman 2009) called diffusion map. SCA is a class of non-linear techniques for transforming observed data (e.g., photometric colours for each galaxy, where the data lie on a complex subset of p-dimensional space) to a simpler, more natural coordinate system wherein we apply regression to make redshift predictions. As SCA relies upon eigen-decomposition, our training set size is limited to ~ 10,000 galaxies; we use the Nystrom extension to quickly estimate diffusion coordinates for objects not in the training set. We apply our method to 350,738 SDSS main sample galaxies, 29,816 SDSS luminous red galaxies, and 5,223 galaxies from DEEP2 with CFHTLS ugriz photometry. For all three datasets, we achieve prediction accuracies on ...

  13. Photometric Redshifts in the IRAC Shallow Survey

    Energy Technology Data Exchange (ETDEWEB)

    Brodwin, M; Brown, M; Ashby, M; Bian, C; Brand, K; Dey, A; Eisenhardt, P; Eisenstein, D; Gonzalez, A; Huang, J; Kochanek, C; McKenzie, E; Pahre, M; Smith, H; Soifer, B; Stanford, S; Stern, D; Elston, R

    2006-06-13

    Accurate photometric redshifts are calculated for nearly 200,000 galaxies to a 4.5 micron flux limit of {approx} 13 {micro}Jy in the 8.5 deg{sup 2} Spitzer/IRAC Shallow survey. Using a hybrid photometric redshift algorithm incorporating both neural-net and template-fitting techniques, calibrated with over 15,000 spectroscopic redshifts, a redshift accuracy of {sigma} = 0.06 (1+z) is achieved for 95% of galaxies at 0 < z < 1.5. The accuracy is {sigma} = 0.12 (1 + z) for 95% of AGN at 0 < z < 3. Redshift probability functions, central to several ongoing studies of the galaxy population, are computed for the full sample. We demonstrate that these functions accurately represent the true redshift probability density, allowing the calculation of valid confidence intervals for all objects. These probability functions have already been used to successfully identify a population of Spitzer-selected high redshift (z > 1) galaxy clusters. We present one such spectroscopically confirmed cluster at = 1.24, ISCS J1434.2+3426. Finally, we present a measurement of the 4.5 {micro}m-selected galaxy redshift distribution.

  14. Global distributions of diurnal and semi-diurnal tides: observations from HRDI-UARS of the MLT region

    Directory of Open Access Journals (Sweden)

    A. H. Manson

    Full Text Available HRDI (High Resolution Doppler Interferometer-UARS winds data have been analyzed in 4° latitude by 10° longitude cells at 96 km to obtain global contour maps of solar-tidal amplitudes and phases, and also mean winds. The solstices June–July (1993, December–January (1993–1994, and one equinox September–October (1994 are shown. 

    The 24-h diurnal tide that maximizes near the 20–25° latitude has significant seasonal changes with equinoctial maxima, and very clear longitudinal variability. Maxima are very clear over the oceans. In contrast, the 12-h semi-diurnal tides that maximize near the 40–55° latitude have very strong seasonal changes with winter maxima, and more modest longitudinal changes. The similarities with MLT (mesosphere-lower thermosphere radar observations (90 km and the GSWM (Global Scale Wave Model are very satisfactory. The mean winds are consistent with expectations and show clear poleward flow from summer to winter hemispheres in the solstices.

    Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides Radio science (remote sensing

  15. Modelled and Observed Diurnal SST Signals: "SSTDV:R.EX.-IM.A.M." Project Preliminary Results

    DEFF Research Database (Denmark)

    Karagali, Ioanna; Høyer, Jacob; LeBorgne, Pierre

    2013-01-01

    This study presents some of the preliminary results from the ESA Support To Science Element (STSE) funded project on the Diurnal Variability of the Sea Surface Temperature, regarding its Regional Extend and Implications in Atmospheric Modelling (SSTDV:R.EX.–IM.A.M.). During this phase...... of the project, the focus is on the regional extend of diurnal variability. Particularly, extensive sensitivity tests regarding the definition of SSTfound fields show that using only quality 5 SEVIRI data results in warmer foundation fields SSTfound while there is an added ∼0.2 K variability when using multi...... Ocean Turbulence Model (GOTM) is applied. Preliminary results show that the initial temperature profiles may give a warmer start-up in the model while the light extinction scheme is a controlling factor for the amplitude and vertical extend of the daily signal....

  16. Photometric activity of the Herbig Be star MWC 297 over 25 years

    Science.gov (United States)

    Barsunova, O. Yu.; Mel'nikov, S. Yu.; Grinin, V. P.; Katysheva, N. A.; Shugarov, S. Yu.

    2013-02-01

    The photometric behavior of the hot, young Herbig Be starMWC 297 on various time scales is studied using published data, as well as new observations. The series of photometric observations covers about 25 years. Over this time, the star showed low-amplitude (Δ V ≈ 0.3 m ) irregular variabilitymodulated by large-scale cyclic variabilitywith an amplitude close to 0.2 m and a period (or quasi-period) of 5.4±0.1 yr. A detailed seasonal analysis of the data shows that the light curve of MWC 297 displays two types of photometric features: low-amplitude Algol-like fading with an amplitude close to 0.2 m and low-amplitude flares resembling the flares of UV Ceti stars, but being more powerful and having longer durations. The variations of the stellar brightness are accompanied by variations of the B- V and V - R colors: when the brightness decreases, B- V decreases, while V - R increases (the star reddens). The reddening law is close to the standard interstellar reddening law. Although the character of the brightness variability ofMWC 297 resembles the photometric activity of UX Ori type stars, which is due to variations of their circumstellar extinction, its scale is very far from the scales observed for UX Ori stars. It is difficult to reconcile the level of photometric activity with the idea that MWC 297 is observed through its own gas-dust disk viewed almost edge-on, as has been suggested in several studies.

  17. Modelling of diurnal cycle under climate change

    Energy Technology Data Exchange (ETDEWEB)

    Eliseev, A.V.; Bezmenov, K.V.; Demchenko, P.F.; Mokhov, I.I.; Petoukhov, V.K. [Russian Academy of Sciences, Moscow (Russian Federation). Inst. of Atmospheric Physics

    1995-12-31

    The observed diurnal temperature range (DTR) displays remarkable change during last 30 years. Land air DTR generally decreases under global climate warming due to more significant night minimum temperature increase in comparison with day maximum temperature increase. Atmosphere hydrological cycle characteristics change under global warming and possible background aerosol atmosphere content change may cause essential errors in the estimation of DTR tendencies of change under global warming. The result of this study is the investigation of cloudiness effect on the DTR and blackbody radiative emissivity diurnal range. It is shown that in some cases (particularly in cold seasons) it results in opposite change in DTR and BD at doubled CO{sub 2} atmosphere content. The influence of background aerosol is the same as the cloudiness one

  18. Diurnal Emotional States Impact the Sleep Course

    OpenAIRE

    Julien Delannoy; Osamu Mandai; Jacques Honoré; Toshinori Kobayashi; Henrique Sequeira

    2015-01-01

    Background Diurnal emotional experiences seem to affect several characteristics of sleep architecture. However, this influence remains unclear, especially for positive emotions. In addition, electrodermal activity (EDA), a sympathetic robust indicator of emotional arousal, differs depending on the sleep stage. The present research has a double aim: to identify the specific effects of pre-sleep emotional states on the architecture of the subsequent sleep period; to relate such states to the sy...

  19. A study of diurnal variation of indoor radon concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Ramola, R.C.; Kandari, M.S.; Negi, M.S. [H.N.B. Garhwal Univ. (India); Choubey, V.M.

    2000-06-01

    Since there are scarce data of diurnal variation of indoor radon levels in houses, authors measured it in different types of houses in Budhakedar (B, mud houses) and Tehri (T, ordinary concrete ones) of Garhwal Himalaya in comparison with environmental parameters. The portable AlphaGUARD (M/S Genitron Instr.) which having an ionization chamber detector, used for measurement was kept inside the houses for about 24 hr to record the levels of radon and environmental variables like air temperature. The indoor radon concentration for a well-ventilated house was found to vary largely within 24 hr. The concentrations in February 1998 were 40-784 Bq/m{sup 3} in B and 12-338 Bq/m{sup 3} in T inside the houses, the latter of which was found affected by the environmental parameters. Radon concentrations in mud houses were higher than those in T. (K.H.)

  20. Asteroid models from the Lowell photometric database

    Science.gov (United States)

    Ďurech, J.; Hanuš, J.; Oszkiewicz, D.; Vančo, R.

    2016-03-01

    Context. Information about shapes and spin states of individual asteroids is important for the study of the whole asteroid population. For asteroids from the main belt, most of the shape models available now have been reconstructed from disk-integrated photometry by the lightcurve inversion method. Aims: We want to significantly enlarge the current sample (~350) of available asteroid models. Methods: We use the lightcurve inversion method to derive new shape models and spin states of asteroids from the sparse-in-time photometry compiled in the Lowell Photometric Database. To speed up the time-consuming process of scanning the period parameter space through the use of convex shape models, we use the distributed computing project Asteroids@home, running on the Berkeley Open Infrastructure for Network Computing (BOINC) platform. This way, the period-search interval is divided into hundreds of smaller intervals. These intervals are scanned separately by different volunteers and then joined together. We also use an alternative, faster, approach when searching the best-fit period by using a model of triaxial ellipsoid. By this, we can independently confirm periods found with convex models and also find rotation periods for some of those asteroids for which the convex-model approach gives too many solutions. Results: From the analysis of Lowell photometric data of the first 100 000 numbered asteroids, we derived 328 new models. This almost doubles the number of available models. We tested the reliability of our results by comparing models that were derived from purely Lowell data with those based on dense lightcurves, and we found that the rate of false-positive solutions is very low. We also present updated plots of the distribution of spin obliquities and pole ecliptic longitudes that confirm previous findings about a non-uniform distribution of spin axes. However, the models reconstructed from noisy sparse data are heavily biased towards more elongated bodies with high

  1. Diurnal and Semidiurnal Variations in Earth Rotation

    Science.gov (United States)

    Weijing, Q.; Xu, X.; Dong, D.; Zhou, Y.

    2016-12-01

    In recent decades, earth orientation has been monitored with increasing accuracy by advanced space-geodetic techniques, including Satellite Laser ranging (SLR), Very Long Baseline Interferometry (VLBI) and the Global Positioning System (GPS). We are able to obtain the Earth Rotation Parameters (ERP, polar motion and rotation rate changes) by even 1 to 2 hours observation data, form which obvious diurnal and semidiurnal signals can be detected, and compare them with the predicted results by the ocean model. Both the amplitude and phase are in good agreement in the main diurnal and semidiurnal wave frequency, especially for the UT1 with Consistency of 90% , and 60% for polar motion, there are 30% motivating factor of the diurnal and semidiurnal polar motion have not been identified. This work add the motivating term libration to the empirical tidal models, which can reduce the difference between the high frequency earth rotation model and observations. Then the numerical simulated ocean tidal model is obtained with the newest ERP datas from GPS, and the Scaled Sensitivity Matrix (SSM) approach is used to separate the sidebands in major ocean tides.

  2. Annual and diurnal African biomass burning temporal dynamics

    Directory of Open Access Journals (Sweden)

    G. Roberts

    2008-09-01

    Full Text Available Africa is the single largest continental source of biomass burning emissions. Here we conduct the first analysis of one full year of geostationary active fire detections and fire radiative power data recorded over Africa at 15-min temporal resolution and a 3 km sampling distance (at the sub-satellite point by the SEVIRI imaging radiometer onboard the Meteosat-8 satellite. We use these data to provide new insights into the rates and totals of African open biomass burning, particularly into the extremely strong seasonal and diurnal cycles that exist across the continent. We find peak daily biomass combustion totals are 9 and 6 million tonnes per day in the Northern and Southern Hemispheres respectively, and total fuel consumption between February 2004 and January 2005 is at least 855 million tonnes. Analysis is carried out with regard to fire pixel temporal persistence, and we note that the majority of African fires are detected only once in consecutive 15 min imaging slots, indicating the importance of optimizing the fire pixel detection strategy performance. An investigation of the variability of the diurnal fire cycle is carried out with respect to 20 land cover types, and whilst differences are noted between land covers, the diurnal characteristics for a given land cover type are similar in both African hemispheres. We compare the FRP-derived biomass combustion estimates to burned-areas, both at the scale of individual fires and over the entire continent at a 1-degree spatial scale. Fuel consumption estimates are found to be less than 2 kg/m2 for almost all land cover types, and for savanna grasslands where literature values are commonly reported the FRP-derived median fuel consumption estimate of 309 g/m2 appears reasonable. From mid-2008, geostationary FRP data of the type presented here will become available to interested users continuously and in near real-time from the EUMETSAT Land Surface Analysis Satellite

  3. Planck 2013 results. VIII. HFI photometric calibration and mapmaking

    DEFF Research Database (Denmark)

    Planck Collaboration,; Ade, P. A. R.; Aghanim, N.;

    2013-01-01

    This paper describes the processing applied to the HFI cleaned time-ordered data to produce photometrically calibrated maps. HFI observes the sky over a broad range of frequencies, from 100 to 857 GHz. To get the best accuracy on the calibration on such a large range, two different photometric ca...

  4. Photometrical research geostationary satellite "SBIRS GEO-2"

    Science.gov (United States)

    Sukhov, P. P.; Epishev, V. P; Sukhov, K. P; Kudak, V. I.

    The multicolor photometrical observations GSS "Sbirs Geo-2" were carried in B,V,R filters out during the autumn equinox 2014 and spring 2015 y. Periodic appearance of many light curves and dips of mirror reflections suggests that the GSS was not in orbit in a static position, predetermined three-axis orientation and in dynamic motion. On the basis of computer modeling suggests the following dynamics GSS "Sbirs Geo-2" in orbit. Helically scanning the visible Earth's surface infrared satellite sensors come with period P1 = 15.66 sec. and the rocking of the GSS about the direction of the motion vector of the satellite in orbit with P2 = 62.64 sec., most likely with the purpose to survey the greatest possible portion of the earth's surface.

  5. Photometric Supernova Classification With Machine Learning

    CERN Document Server

    Lochner, Michelle; Peiris, Hiranya V; Lahav, Ofer; Winter, Max K

    2016-01-01

    Automated photometric supernova classification has become an active area of research in recent years in light of current and upcoming imaging surveys such as the Dark Energy Survey (DES) and the Large Synoptic Telescope (LSST), given that spectroscopic confirmation of type for all supernovae discovered with these surveys will be impossible. Here, we develop a multi-faceted classification pipeline, combining existing and new approaches. Our pipeline consists of two stages: extracting descriptive features from the light curves and classification using a machine learning algorithm. Our feature extraction methods vary from model-dependent techniques, namely SALT2 fits, to more independent techniques fitting parametric models to curves, to a completely model-independent wavelet approach. We cover a range of representative machine learning algorithms, including naive Bayes, k-nearest neighbors, support vector machines, artificial neural networks and boosted decision trees. We test the pipeline on simulated multi-ba...

  6. Hierarchical Bayesian inference of galaxy redshift distributions from photometric surveys

    CERN Document Server

    Leistedt, Boris; Peiris, Hiranya V

    2016-01-01

    Accurately characterizing the redshift distributions of galaxies is essential for analysing deep photometric surveys and testing cosmological models. We present a technique to simultaneously infer redshift distributions and individual redshifts from photometric galaxy catalogues. Our model constructs a piecewise constant representation (effectively a histogram) of the distribution of galaxy types and redshifts, the parameters of which are efficiently inferred from noisy photometric flux measurements. This approach can be seen as a generalization of template-fitting photometric redshift methods and relies on a library of spectral templates to relate the photometric fluxes of individual galaxies to their redshifts. We illustrate this technique on simulated galaxy survey data, and demonstrate that it delivers correct posterior distributions on the underlying type and redshift distributions, as well as on the individual types and redshifts of galaxies. We show that even with uninformative priors, large photometri...

  7. New insights on the accuracy of photometric redshift measurements

    CERN Document Server

    Massarotti, M; Buzzoni, A; Valls-Gabaud, D

    2001-01-01

    We use the deepest and most complete redshift catalog currently available (the Hubble Deep Field (HDF) North supplemented by new HDF South redshift data) to minimize residuals between photometric and spectroscopic redshift estimates. The good agreement at z_spec 2.0, the systematic shift between photometric and spectroscopic redshifts decreases when the modeling of the absorption by the interstellar and intergalactic media is refined. As a result, in the entire redshift range 0 < z < 6, residuals between photometric and spectroscopic redshifts are roughly halved. For objects fainter than the spectroscopic limit, the main source of uncertainty in photometric redshifts is related to photometric errors, and can be assessed with Monte Carlo simulations.

  8. Photometric Supernova Classification with Machine Learning

    Science.gov (United States)

    Lochner, Michelle; McEwen, Jason D.; Peiris, Hiranya V.; Lahav, Ofer; Winter, Max K.

    2016-08-01

    Automated photometric supernova classification has become an active area of research in recent years in light of current and upcoming imaging surveys such as the Dark Energy Survey (DES) and the Large Synoptic Survey Telescope, given that spectroscopic confirmation of type for all supernovae discovered will be impossible. Here, we develop a multi-faceted classification pipeline, combining existing and new approaches. Our pipeline consists of two stages: extracting descriptive features from the light curves and classification using a machine learning algorithm. Our feature extraction methods vary from model-dependent techniques, namely SALT2 fits, to more independent techniques that fit parametric models to curves, to a completely model-independent wavelet approach. We cover a range of representative machine learning algorithms, including naive Bayes, k-nearest neighbors, support vector machines, artificial neural networks, and boosted decision trees (BDTs). We test the pipeline on simulated multi-band DES light curves from the Supernova Photometric Classification Challenge. Using the commonly used area under the curve (AUC) of the Receiver Operating Characteristic as a metric, we find that the SALT2 fits and the wavelet approach, with the BDTs algorithm, each achieve an AUC of 0.98, where 1 represents perfect classification. We find that a representative training set is essential for good classification, whatever the feature set or algorithm, with implications for spectroscopic follow-up. Importantly, we find that by using either the SALT2 or the wavelet feature sets with a BDT algorithm, accurate classification is possible purely from light curve data, without the need for any redshift information.

  9. The effect of photometric and geometric context on photometric and geometric lightness effects

    OpenAIRE

    Lee, Thomas Y.; Brainard, David H

    2014-01-01

    We measured the lightness of probe tabs embedded at different orientations in various contextual images presented on a computer-controlled stereo display. Two background context planes met along a horizontal roof-like ridge. Each plane was a graphic rendering of a set of achromatic surfaces with the simulated illumination for each plane controlled independently. Photometric context was varied by changing the difference in simulated illumination intensity between the two background planes. Geo...

  10. A photometric determination of the metal content for Cepheids in the Small Magellanic Cloud

    Science.gov (United States)

    Pel, J. W.; van Genderen, A. M.; Lub, J.

    1981-06-01

    A description is given of results which were obtained in studies of the photometry of SMC Cepheids conducted with the aid of the Walraven VBLUW photometric system. Twenty variables outside the dense central regions had been selected in the SMC. The results confirm the differences in VBLUW colors between galactic and SMC Cepheids reported by van Genderen (1977). They also support similar color effects found in other photometric systems. Composition is not the only possible cause of these color differences, however. An alternative has been proposed by DeYoreo and Karp (1979), who ascribe the blueness of SMC Cepheids to contamination by companions. Such an explanation is not supported by the presented data. A metal deficiency of a factor 5 with respect to the sun is obtained. This value agrees with data reported by Wallerstein (1980) and Smith (1980).

  11. Clues To The Nature of SN 2009ip from Photometric and Spectroscopic Evolution to Late Times

    CERN Document Server

    Graham, M L; Valenti, S; Howell, D A; Parrent, J; Halford, M; Zaritsky, D; Bianco, F; Rest, A; Dilday, B

    2014-01-01

    We present time series photometric and spectroscopic data for the transient SN 2009ip from the start of its outburst in September 2012 until November 2013. This data was collected primarily with the new robotic capabilities of the Las Cumbres Observatory Global Telescope Network, a specialized facility for time domain astrophysics, and includes supporting high-resolution spectroscopy from the Southern Astrophysical Research Telescope, Kitt Peak National Observatory, and Gemini Observatory. Based on our nightly photometric monitoring, we interpret the strength and timing of fluctuations in the light curve as interactions between fast-moving ejecta and an inhomogeneous CSM produced by past eruptions of this massive luminous blue variable (LBV) star. Our time series of spectroscopy in 2012 reveals that, as the continuum and narrow H-alpha flux from CSM interactions declines, the broad component of H-alpha persists with SN-like velocities that are not typically seen in LBVs or SN Impostor events. At late times we...

  12. Covariability in the Monthly Mean Convective and Radiative Diurnal Cycles in the Amazon

    Science.gov (United States)

    Dodson, Jason B.; Taylor, Patrick C.

    2015-01-01

    The diurnal cycle of convective clouds greatly influences the radiative energy balance in convectively active regions of Earth, through both direct presence, and the production of anvil and stratiform clouds. Previous studies show that the frequency and properties of convective clouds can vary on monthly timescales as a result of variability in the monthly mean atmospheric state. Furthermore, the radiative budget in convectively active regions also varies by up to 7 Wm-2 in convectively active regions. These facts suggest that convective clouds connect atmospheric state variability and radiation variability beyond clear sky effects alone. Previous research has identified monthly covariability between the diurnal cycle of CERES-observed top-of-atmosphere radiative fluxes and multiple atmospheric state variables from reanalysis over the Amazon region. ASVs that enhance (reduce) deep convection, such as CAPE (LTS), tend to shift the daily OLR and cloud albedo maxima earlier (later) in the day by 2-3 hr. We first test the analysis method using multiple reanalysis products for both the dry and wet seasons to further investigate the robustness of the preliminary results. We then use CloudSat data as an independent cloud observing system to further evaluate the relationships of cloud properties to variability in radiation and atmospheric states. While CERES can decompose OLR variability into clear sky and cloud effects, it cannot determine what variability in cloud properties lead to variability in the radiative cloud effects. Cloud frequency, cloud top height, and cloud microphysics all contribute to the cloud radiative effect, all of which are observable by CloudSat. In addition, CloudSat can also observe the presence and variability of deep convective cores responsible for the production of anvil clouds. We use these capabilities to determine the covariability of convective cloud properties and the radiative diurnal cycle.

  13. Photometric and Polarimetric Activity of the Herbig Ae Star VX Cas

    Science.gov (United States)

    Shakhovskoi, D. N.; Rostopchina, A. N.; Grinin, V. P.; Minikulov, N. Kh.

    2003-04-01

    We present the results of our simultaneous photometric and polarimetric observations of the Herbig Ae/Be star VX Cas acquired in 1987 2001. The star belongs to the UX Ori subtype of young variable stars and exhibits a rather low level of photometric activity: only six Algol-like minima with amplitudes ΔV>1m were recorded in 15 years of observations. Two of these minima, in 1998 and 2001, were the deepest in the history of the star’s photometric studies, with V amplitudes of about 2m. In each case, the dimming was accompanied by an increase in the linear polarization in agreement with the law expected for variable circumstellar extinction. The highest V polarization was about 5%. Observations of VX Cas in the deep minima revealed a turnover of the color tracks, typical of stars of this type and due to an increased contribution from radiation scattered in the circumstellar disk. We separated the observed polarization of VX Cas into interstellar (P is) and intrinsic (P in) components. Their position angles differ by approximately 60°, with P is dominating in the bright state and P in dominating during the deep minima. The competition of these two polarization components leads to changes in both the degree and position angle of the polarization during the star’s brightness variations. Generally speaking, in terms of the behavior of the brightness, color indices, and linear polarization, VX Cas is similar to other UX Ori stars studied by us earlier. A number of episodes of photometric and polarimetric activity suggest that, in their motion along highly eccentric orbits, circumstellar gas and dust clouds can enter the close vicinity of the star (and be disrupted there).

  14. Diurnal variation and dispersion in QT interval in cirrhosis: relation to haemodynamic changes

    DEFF Research Database (Denmark)

    Hansen, Stig; Møller, Søren; Bendtsen, Flemming

    2007-01-01

    with cirrhosis, undergoing a haemodynamic investigation. 24-h 12 lead Holter monitoring provided information on QT and heart rate variability. RESULTS: Mean QT(C) was above upper normal limit (440 ms(1/2)) in eleven patients (47%) and significantly higher than in controls (441 vs 400 ms(1/2), p...=0.03-0.001). No diurnal variation of QT(disp) was found in cirrhosis. Heart rate variability was reduced with a significant relation to central hypovolaemia (r=0.55, p=0.01). CONCLUSIONS: Twenty-four hours QT(C) is prolonged in a substantial fraction of patients with cirrhosis, but with normal...... diurnal variation. The combination of long QT(C) and normal QT(disp) suggests delayed myocyte repolarisation on the cellular level, rather than temporal and spatial heterogeneity in the myocardial wall....

  15. SIDRA: a blind algorithm for signal detection in photometric surveys

    Science.gov (United States)

    Mislis, D.; Bachelet, E.; Alsubai, K. A.; Bramich, D. M.; Parley, N.

    2016-01-01

    We present the Signal Detection using Random-Forest Algorithm (SIDRA). SIDRA is a detection and classification algorithm based on the Machine Learning technique (Random Forest). The goal of this paper is to show the power of SIDRA for quick and accurate signal detection and classification. We first diagnose the power of the method with simulated light curves and try it on a subset of the Kepler space mission catalogue. We use five classes of simulated light curves (CONSTANT, TRANSIT, VARIABLE, MLENS and EB for constant light curves, transiting exoplanet, variable, microlensing events and eclipsing binaries, respectively) to analyse the power of the method. The algorithm uses four features in order to classify the light curves. The training sample contains 5000 light curves (1000 from each class) and 50 000 random light curves for testing. The total SIDRA success ratio is ≥90 per cent. Furthermore, the success ratio reaches 95-100 per cent for the CONSTANT, VARIABLE, EB and MLENS classes and 92 per cent for the TRANSIT class with a decision probability of 60 per cent. Because the TRANSIT class is the one which fails the most, we run a simultaneous fit using SIDRA and a Box Least Square (BLS)-based algorithm for searching for transiting exoplanets. As a result, our algorithm detects 7.5 per cent more planets than a classic BLS algorithm, with better results for lower signal-to-noise light curves. SIDRA succeeds to catch 98 per cent of the planet candidates in the Kepler sample and fails for 7 per cent of the false alarms subset. SIDRA promises to be useful for developing a detection algorithm and/or classifier for large photometric surveys such as TESS and PLATO exoplanet future space missions.

  16. Annual and diurnal african biomass burning temporal dynamics

    Directory of Open Access Journals (Sweden)

    G. Roberts

    2009-05-01

    Full Text Available Africa is the single largest continental source of biomass burning emissions. Here we conduct the first analysis of one full year of geostationary active fire detections and fire radiative power data recorded over Africa at 15-min temporal interval and a 3 km sub-satellite spatial resolution by the Spinning Enhanced Visible and Infrared Imager (SEVIRI imaging radiometer onboard the Meteosat-8 satellite. We use these data to provide new insights into the rates and totals of open biomass burning over Africa, particularly into the extremely strong seasonal and diurnal cycles that exist across the continent. We estimate peak daily biomass combustion totals to be 9 and 6 million tonnes of fuel per day in the northern and southern hemispheres respectively, and total fuel consumption between February 2004 and January 2005 is estimated to be at least 855 million tonnes. Analysis is carried out with regard to fire pixel temporal persistence, and we note that the majority of African fires are detected only once in consecutive 15 min imaging slots. An investigation of the variability of the diurnal fire cycle is carried out with respect to 20 different land cover types, and whilst differences are noted between land covers, the fire diurnal cycle characteristics for most land cover type are very similar in both African hemispheres. We compare the Fire Radiative Power (FRP derived biomass combustion estimates to burned-areas, both at the scale of individual fires and over the entire continent at a 1-degree scale. Fuel consumption estimates are found to be less than 2 kg/m2 for all land cover types noted to be subject to significant fire activity, and for savanna grasslands where literature values are commonly reported the FRP-derived median fuel consumption estimate of 300 g/m2 is well within commonly quoted values. Meteosat-derived FRP data of the type presented here is now available freely to interested users continuously and in near

  17. Daily diurnal variation in admissions for ruptured abdominal aortic aneurysms.

    LENUS (Irish Health Repository)

    Killeen, Shane

    2012-02-03

    BACKGROUND: Many vascular events, such as myocardial infarction and cerebrovascular accident, demonstrate a circadian pattern of presentation. Blood pressure is intimately related to these pathologies and is the one physiological variable consistently associated with abdominal aortic aneurysm rupture. It also demonstrates a diurnal variation. The purpose of this study was to determine if rupture of an abdominal aortic aneurysm (RAAA) exhibits a diurnal variation. METHODS: A retrospective cohort-based study was performed to determine the timing of presentation of RAAA to the vascular unit of Cork University Hospital over a 15-year period. Time of admission, symptom onset, and co-morbidities such as hypertension were noted. Fournier\\'s analysis and chi-squared analysis were performed. To ameliorate possible confounding factors, patients admitted with perforated peptic ulcers were examined in the same manner. RESULTS: A total of 148 cases of RAAA were identified, with a male preponderance (71.7% [124] male versus 29.3% [44] female patients) and a mean age of 74.4 +\\/- 7.2 years at presentation. 70.9% (105) were known to have hypertension, 52.2% (77) were current smokers, and 46.8% (69) were being treated for chronic obstructive airway disease (COAD). Time of symptom onset was recorded in 88.5% (131) of patients. There was a marked early morning peak in RAAA admissions, with the highest number of RAAA being admitted between 08.00 and 09.59. A second, smaller peak was observed at 14.00-15.59. These findings were suggestive of diurnal variation. [chi(2) =16.75, p < 0.003]. Some 40% (59) of patients were admitted between 00.00 and 06.00, an incidence significantly higher than for other time periods (06.00-12.00, 12.00-18.00, and 18.00-24.00) [chi(2) = 18.72; df = 3; p < 0.0003]. A significantly higher number of patients admitted between 00.00 and 06.00 were known hypertensives (chi(2) = 7.94; p < 0.05). CONCLUSIONS: The findings of this study suggest a distinct

  18. THE APPARATUS FOR ALIGNMENT OF THE PHOTOMETRIC LAMP FILAMENT

    Directory of Open Access Journals (Sweden)

    V. A. Dlugunovich

    2015-01-01

    Full Text Available During photometric measurements involving the use of photometric lamps it is necessary that the filament of lamp takes a strictly predetermined position with respect to the photodetector and the optical axis of the photometric setup. The errors in positioning of alignment filament with respect to the optical axis of the measuring system lead to increase the uncertainty of measurement of the photometric characteristics of the light sources. A typical method for alignment of filament of photometric lamps is based on the use a diopter tubes (telescopes. Using this method, the mounting of filament to the required position is carried out by successive approximations, which requires special concentration and a lot of time. The aim of this work is to develop an apparatus for alignment which allows simultaneous alignment of the filament of lamps in two mutually perpendicular planes. The method and apparatus for alignment of the photometric lamp filament during measurements of the photometric characteristics of light sources based on two digital video cameras is described in this paper. The apparatus allows to simultaneously displaying the image of lamps filament on the computer screen in two mutually perpendicular planes. The apparatus eliminates a large number of functional units requiring elementwise alignment and reduces the time required to carry out the alignment. The apparatus also provides the imaging of lamps filament with opaque coated on the bulb. The apparatus is used at the National standard of light intensity and illuminance units of the Republic of Belarus. 

  19. Observations of seasonal and diurnal glacier velocities at Mount Rainier, Washington, using terrestrial radar interferometry

    Science.gov (United States)

    Allstadt, K. E.; Shean, D. E.; Campbell, A.; Fahnestock, M.; Malone, S. D.

    2015-12-01

    We present surface velocity maps derived from repeat terrestrial radar interferometry (TRI) measurements and use these time series to examine seasonal and diurnal dynamics of alpine glaciers at Mount Rainier, Washington. We show that the Nisqually and Emmons glaciers have small slope-parallel velocities near the summit ( 10 km range can be used to investigate spatial and temporal variability of alpine glacier dynamics over large areas, including hazardous and inaccessible areas.

  20. One Moon, many measurements 2: Photometric corrections

    Science.gov (United States)

    Besse, S.; Yokota, Y.; Boardman, J.; Green, R.; Haruyama, J.; Isaacson, P.; Mall, U.; Matsunaga, T.; Ohtake, M.; Pieters, C.; Staid, M.; Sunshine, J.; Yamamoto, S.

    2013-09-01

    Observations of the lunar surface within the past 10 years have been made with various lunar remote sensing instruments, the Moon Mineralogy Mapper (M3) onboard the Chandrayaan-1 mission, the Spectral Profiler (SP), the Multiband Imager (MI), the Terrain Camera (TC) onboard the SELENE mission, and the ground based USGS Robotic Lunar Observatory (ROLO) for some of them. The lunar phase functions derived from these datasets, which are used in the photometric modeling to correct for the various illumination conditions of the data, are compared to assess their differences and similarity in order to improve interpretations of lunar surface spectra. The phase functions are found to be similar across various phase angles except in the 0-20° range. Differences across the 0-20° range likely result from two different inputs in the photometric modeling of the M3 and SP data: (1) M3 has larger emission angles due to the characteristics of the instrument and the attitude of the spacecraft, and (2) M3 viewing geometry was derived from the local topography whereas SP used a spherical Moon (no topography). The combination of these two different inputs affects the phase function at small phase angles where shadows play a more substantial role, with spatial resolution differences between M3 and SP being another possible source for the differences. SP data are found to be redder (i.e., steeper slope with increasing wavelengths) than MI, M3 and ROLO. Finally, the M3 overall reflectance is also found to be lower than that the other instruments (i.e., MI, SP, and ROLO), generally at least 10% darker than MI. These differences can be observed at local scales in specific examples at hundreds of meters resolutions. At regional and global scales, the same differences are found, which demonstrates the overall stability of the various datasets. The observations from M3, TC, SP and MI are very stable and agree well; however caution should be used when making interpretations based on the

  1. Application of the Trend Filtering Algorithm for Photometric Time Series Data

    Science.gov (United States)

    Gopalan, Giri; Plavchan, Peter; van Eyken, Julian; Ciardi, David; von Braun, Kaspar; Kane, Stephen R.

    2016-08-01

    Detecting transient light curves (e.g., transiting planets) requires high-precision data, and thus it is important to effectively filter systematic trends affecting ground-based wide-field surveys. We apply an implementation of the Trend Filtering Algorithm (TFA) to the 2MASS calibration catalog and select Palomar Transient Factory (PTF) photometric time series data. TFA is successful at reducing the overall dispersion of light curves, however, it may over-filter intrinsic variables and increase “instantaneous” dispersion when a template set is not judiciously chosen. In an attempt to rectify these issues we modify the original TFA from the literature by including measurement uncertainties in its computation, including ancillary data correlated with noise, and algorithmically selecting a template set using clustering algorithms as suggested by various authors. This approach may be particularly useful for appropriately accounting for variable photometric precision surveys and/or combined data sets. In summary, our contributions are to provide a MATLAB software implementation of TFA and a number of modifications tested on synthetics and real data, summarize the performance of TFA and various modifications on real ground-based data sets (2MASS and PTF), and assess the efficacy of TFA and modifications using synthetic light curve tests consisting of transiting and sinusoidal variables. While the transiting variables test indicates that these modifications confer no advantage to transit detection, the sinusoidal variables test indicates potential improvements in detection accuracy.

  2. Diurnal emissivity dynamics in bare versus biocrusted sand dunes

    Science.gov (United States)

    Rozenstein, O.

    2015-12-01

    Land surface emissivity (LSE) in the thermal infrared depends mainly on the ground cover and on changes in soil moisture. The LSE is a critical variable that affects the prediction accuracy of geophysical models requiring land surface temperature as an input, highlighting the need for an accurate derivation of LSE. The primary aim of this study was to test the hypothesis that diurnal changes in emissivity, as detected from space, are larger for areas mostly covered by biocrusts (composed mainly of cyanobacteria) than for bare sand areas. The LSE dynamics were monitored from geostationary orbit by the Spinning Enhanced Visible and Infrared Imager (SEVIRI) over a sand dune field in a coastal desert region extending across both sides of the Israel-Egypt political borderline. Different land-use practices by the two countries have resulted in exposed, active sand dunes on the Egyptian side (Sinai), and dunes stabilized by biocrusts on the Israeli side (Negev). Since biocrusts adsorb more moisture from the atmosphere than bare sand does, and LSE is affected by the soil moisture, diurnal fluctuations in LSE were larger for the crusted dunes in the 8.7 μm channel. This phenomenon is attributed to water vapor adsorption by the sand / biocrust particles. The results indicate that LSE is sensitive to minor changes in soil water content caused by water vapor adsorption and can, therefore, serve as a tool for quantifying this effect, which has a large spatial impact. As biocrusts cover vast regions in deserts worldwide, this discovery has repercussions for LSE estimations in deserts around the globe, and these LSE variations can potentially have considerable effects on geophysical models from local to regional scales.

  3. Diurnal emissivity dynamics in bare versus biocrusted sand dunes.

    Science.gov (United States)

    Rozenstein, Offer; Agam, Nurit; Serio, Carmine; Masiello, Guido; Venafra, Sara; Achal, Stephen; Puckrin, Eldon; Karnieli, Arnon

    2015-02-15

    Land surface emissivity (LSE) in the thermal infrared depends mainly on the ground cover and on changes in soil moisture. The LSE is a critical variable that affects the prediction accuracy of geophysical models requiring land surface temperature as an input, highlighting the need for an accurate derivation of LSE. The primary aim of this study was to test the hypothesis that diurnal changes in emissivity, as detected from space, are larger for areas mostly covered by biocrusts (composed mainly of cyanobacteria) than for bare sand areas. The LSE dynamics were monitored from geostationary orbit by the Spinning Enhanced Visible and Infrared Imager (SEVIRI) over a sand dune field in a coastal desert region extending across both sides of the Israel-Egypt political borderline. Different land-use practices by the two countries have resulted in exposed, active sand dunes on the Egyptian side (Sinai), and dunes stabilized by biocrusts on the Israeli side (Negev). Since biocrusts adsorb more moisture from the atmosphere than bare sand does, and LSE is affected by the soil moisture, diurnal fluctuations in LSE were larger for the crusted dunes in the 8.7 μm channel. This phenomenon is attributed to water vapor adsorption by the sand/biocrust particles. The results indicate that LSE is sensitive to minor changes in soil water content caused by water vapor adsorption and can, therefore, serve as a tool for quantifying this effect, which has a large spatial impact. As biocrusts cover vast regions in deserts worldwide, this discovery has repercussions for LSE estimations in deserts around the globe, and these LSE variations can potentially have considerable effects on geophysical models from local to regional scales.

  4. Photometric Redshift Estimation on SDSS Data Using Random Forests

    CERN Document Server

    Carliles, Samuel; Heinis, Sebastien; Priebe, Carey; Szalay, Alexander

    2007-01-01

    Given multiband photometric data from the SDSS DR6, we estimate galaxy redshifts. We employ a Random Forest trained on color features and spectroscopic redshifts from 80,000 randomly chosen primary galaxies yielding a mapping from color to redshift such that the difference between the estimate and the spectroscopic redshift is small. Our methodology results in tight RMS scatter in the estimates limited by photometric errors. Additionally, this approach yields an error distribution that is nearly Gaussian with parameter estimates giving reliable confidence intervals unique to each galaxy photometric redshift.

  5. Limits on the infrared photometric monitoring of brown dwarfs

    CERN Document Server

    Bailer-Jones, C A L

    2003-01-01

    Recent monitoring programs of ultra cool field M and L dwarfs (low mass stars or brown dwarfs) have uncovered low amplitude photometric I-band variations which may be associated with an inhomogeneous distribution of photospheric condensates. Further evidence hints that this distribution may evolve on very short timescales, specifically of order a rotation period or less. In an attempt to study this behaviour in more detail, we have carried out a pilot program to monitor three L dwarfs in the near infrared where these objects are significantly brighter than at shorter wavelengths. We present a robust data analysis method for improving the precision and reliability of infrared photometry. No significant variability was detected in either the J or Km bands in 2M1439 and SDSS1203 above a peak-to-peak amplitude of 0.04 mag (0.08 mag for 2M1112). The main limiting factor in achieving lower detection limits is suspected to be second order extinction effects in the Earth's atmosphere, on account of the very different...

  6. The post-outburst photometric behaviour of V838 Mon

    CERN Document Server

    Crause, L A; Kilkenny, D; Van Wyk, F; Marang, F; Jones, A F; Crause, Lisa A.; Lawson, Warrick A.; Kilkenny, David; Wyk, Francois van; Marang, Fred; Jones, Albert F.

    2003-01-01

    The unusual eruptive variable discovered in Monoceros in 2002 January underwent dramatic photometric and spectroscopic changes in the months prior to its 2002 June-August conjunction with the Sun. Optical and infrared (IR) photometry obtained at the South African Astronomical Observatory (SAAO) between 2002 January and June (JD 2452280-440) is presented here in an analysis of the star's post-outburst behaviour. The light curve indicated 3 eruptions took place in 2002 January, February and March. SAAO echelle spectra obtained in the week prior to the March maximum indicated the ejection of a new shell of material. JHKL photometry obtained during 2002 April showed the development of an IR excess due to the formation of a dust shell. The shell appears to be largely responsible for the rapid fade in the optical flux during 2002 April-May (Delta V > 6 mag within 3 weeks). Blueing of the optical colours during the decline is likely due either to the revealing of an emission line region surrounding V838 Mon, or the ...

  7. A Spectroscopic and Photometric Survey of Novae in M31

    CERN Document Server

    Shafter, A W; Hornoch, K; Filippenko, A V; Bode, M F; Ciardullo, R; Misselt, K A; Hounsell, R A; Chornock, R; Matheson, T

    2011-01-01

    We report the results of a multi-year spectroscopic and photometric survey of novae in M31 that resulted in a total of 53 spectra of 48 individual nova candidates. Two of these, M31N 1995-11e and M31N 2007-11g, were revealed to be long-period Mira variables, not novae. These data double the number of spectra extant for novae in M31 through the end of 2009 and bring to 91 the number of M31 novae with known spectroscopic classifications. We find that 75 novae (82%) are confirmed or likely members of the Fe II spectroscopic class, with the remaining 16 novae (18%) belonging to the He/N (and related) classes. These numbers are consistent with those found for Galactic novae. We find no compelling evidence that spectroscopic class depends sensitively on spatial position or population within M31 (i.e., bulge vs. disk), although the distribution for He/N systems appears slightly more extended than that for the Fe II class. We confirm the existence of a correlation between speed class and ejection velocity (based on l...

  8. Photometric study of the Blazhko star RZ Lyr

    CERN Document Server

    Jurcsik, J; Hajdu, G; Szeidl, B; Dózsa, Á; Posztobányi, K; Smitola, P; Belucz, B; Fehér, V; Kővári, Zs; Kriskovics, L; Kun, E; Molnár, L; Nagy, I; Vida, K; Görög, N

    2012-01-01

    The analysis of recent, extended multicolour CCD and archive photoelectric, photographic and visual observations has revealed several important properties of RZ Lyr, an RRab-type variable exhibiting large-amplitude Blazhko modulation. On the time-base of \\sim110 yr, a strict anticorrelation between the pulsation and modulation period changes is established. The light curve of RZ Lyr shows a remarkable bump on the descending branch in the small-amplitude phase of the modulation, similarly to the light curves of bump Cepheids. We speculate that the stellar structure temporally suits a 4:1 resonance between the periods of the fundamental and one of the higher-order radial modes in this modulation phase. The light-curve variation of RZ Lyr can be correctly fitted with a two-modulation-component solution; the 121 d period of the main modulation is nearly but not exactly four times longer than the period of the secondary modulation component. Using the inverse photometric method, the variations in the pulsation-ave...

  9. Broad Band Photometric Reverberation Mapping of NGC 4395

    CERN Document Server

    Edri, Haim; Chelouche, Doron; Kaspi, Shai; Behar, Ehud

    2012-01-01

    We present results of broad band photometric reverberation mapping (RM) to measure the radius of the broad line region, and subsequently the black hole mass (M$_{\\rm BH}$), in the nearby, low luminosity active galactic nuclei (AGN) NGC 4395. Using the Wise Observatory's 1m telescope equipped with the SDSS g$'$, r$'$ and i$'$ broad band filters, we monitored NGC 4395 for 9 consecutive nights and obtained 3 light curves each with over 250 data points. The g$'$ and r$'$ bands include time variable contributions from H$\\beta$ and H$\\alpha$ (respectively) plus continuum. The i$'$ band is free of broad lines and covers exclusively continuum. We show that by looking for a peak in the difference between the cross-correlation and the auto-correlation functions for all combinations of filters, we can get a reliable estimate of the time lag necessary to compute M$_{\\rm BH}$. We measure the time lag for H$\\alpha$ to be $3.6 \\pm 0.8 $ hours, comparable to previous studies using the line resolved spectroscopic RM method. W...

  10. Photometric immersion refractometry of bacterial spores.

    Science.gov (United States)

    Gerhardt, P; Beaman, T C; Corner, T R; Greenamyre, J T; Tisa, L S

    1982-01-01

    Photometric immersion refractometry was used to determine the average apparent refractive index (n) of five types of dormant Bacillus spores representing a 600-fold range in moist-heat resistance determined as a D100 value. The n of a spore type increased as the molecular size of various immersion solutes decreased. For comparison of the spore types, the n of the entire spore and of the isolated integument was determined by use of bovine serum albumin, which is excluded from permeating into them. The n of the sporoplast (the structures bounded by the outer pericortex membrane) was determined by use of glucose, which was shown to permeate into the spore only as deeply as the pericortex membrane. Among the various spore types, an exponential increase in the heat resistance correlated with the n of the entire spore and of the sporoplast, but not of the isolated perisporoplast integument. Correlation of the n with the solids content of the entire spore provided a method of experimentally obtaining the refractive index increment (dn/dc), which was constant for the various spore types and enables the calculation of solids and water content from an n. Altogether, the results showed that the total water content is distributed unequally within the dormant spore, with less water in the sporoplast than in the perisporoplast integument, and that the sporoplast becomes more refractile and therefore more dehydrated as the heat resistance becomes greater among the various spore types. PMID:6802796

  11. Results from the Supernova Photometric Classification Challenge

    CERN Document Server

    Kessler, Richard; Belov, Pavel; Bhatnagar, Vasudha; Campbell, Heather; Conley, Alex; Frieman, Joshua A; Glazov, Alexandre; Hlozek, Santiago Gonzalez-Gaitan Renee; Jha, Saurabh; Kuhlmann, Stephen; Kunz, Martin; Lampeitl, Hubert; Mahabal, Ashish; Newling, James; Nichol, Robert C; Parkinson, David; Philip, Ninan Sajeeth; Poznanski, Dovi; Richards, Joseph W; Rodney, Steven A; Sako, Masao; Schneider, Donald P; Smith, Mathew; Stritzinger, Maximilian; Varughese, Melvin

    2010-01-01

    We report results from the Supernova Photometric Classification Challenge (SNPCC), a publicly released mix of simulated SNe, with types (Ia, Ibc, II) selected in proportion to their expected rate. The simulation was realized in the griz filters of the Dark Energy Survey (DES) with realistic observing conditions (sky noise, point spread function and atmospheric transparency) based on years of recorded conditions at the DES site. Simulations of non-Ia type SNe are based on spectroscopically confirmed light curves that include unpublished non-Ia samples donated from the Carnegie Supernova Project (CSP), the Supernova Legacy Survey (SNLS), and the Sloan Digital Sky Survey-II (SDSS-II). A spectroscopically confirmed subset was provided for training. We challenged scientists to run their classification algorithms and report a type and photo-z for each SN. Participants from 10 groups contributed 13 entries for the sample that included a host galaxy photo-z for each SN, and 9 entries for the sample that had no redshi...

  12. ASTEP South: a first photometric analysis

    CERN Document Server

    Crouzet, N; Mékarnia, D; Szulágyi, J; Abe, L; Agabi, A; Fanteï-Caujolle, Y; Gonçalves, I; Barbieri, M; Schmider, F -X; Rivet, J -P; Bondoux, E; Challita, Z; Pouzenc, C; Fressin, F; Valbousquet, F; Blazit, A; Bonhomme, S; Daban, J -B; Gouvret, C; Bayliss, D; Zhou, G

    2012-01-01

    The ASTEP project aims at detecting and characterizing transiting planets from Dome C, Antarctica, and qualifying this site for photometry in the visible. The first phase of the project, ASTEP South, is a fixed 10 cm diameter instrument pointing continuously towards the celestial South pole. Observations were made almost continuously during 4 winters, from 2008 to 2011. The point-to-point RMS of 1-day photometric lightcurves can be explained by a combination of expected statistical noises, dominated by the photon noise up to magnitude 14. This RMS is large, from 2.5 mmag at R=8 to 6% at R=14, because of the small size of ASTEP South and the short exposure time (30 s). Statistical noises should be considerably reduced using the large amount of collected data. A 9.9-day period eclipsing binary is detected, with a magnitude R=9.85. The 2-season lightcurve folded in phase and binned into 1000 points has a RMS of 1.09 mmag, for an expected photon noise of 0.29 mmag. The use of the 4 seasons of data with a better d...

  13. Influence of observed diurnal cycles of aerosol optical depth on aerosol direct radiative effect

    Directory of Open Access Journals (Sweden)

    A. Arola

    2013-08-01

    Full Text Available The diurnal variability of aerosol optical depth (AOD can be significant, depending on location and dominant aerosol type. However, these diurnal cycles have rarely been taken into account in measurement-based estimates of aerosol direct radiative forcing (ADRF or aerosol direct radiative effect (ADRE. The objective of our study was to estimate the influence of diurnal aerosol variability at the top of the atmosphere ADRE estimates. By including all the possible AERONET sites, we wanted to assess the influence on global ADRE estimates. While focusing also in more detail on some selected sites of strongest impact, our goal was to also see the possible impact regionally. We calculated ADRE with different assumptions about the daily AOD variability: taking the observed daily AOD cycle into account and assuming diurnally constant AOD. Moreover, we estimated the corresponding differences in ADREs, if the single AOD value for the daily mean was taken from the the Moderate Resolution Imaging Spectroradiometer (MODIS Terra or Aqua overpass times, instead of accounting for the true observed daily variability. The mean impact of diurnal AOD variability on 24 h ADRE estimates, averaged over all AERONET sites, was rather small and it was relatively small even for the cases when AOD was chosen to correspond to the Terra or Aqua overpass time. This was true on average over all AERONET sites, while clearly there can be much stronger impact in individual sites. Examples of some selected sites demonstrated that the strongest observed AOD variability (the strongest morning afternoon contrast does not typically result in a significant impact on 24 h ADRE. In those cases, the morning and afternoon AOD patterns are opposite and thus the impact on 24 h ADRE, when integrated over all solar zenith angles, is reduced. The most significant effect on daily ADRE was induced by AOD cycles with either maximum or minimum AOD close to local noon. In these cases, the impact on

  14. Influence of Observed Diurnal Cycles of Aerosol Optical Depth on Aerosol Direct Radiative Effect

    Science.gov (United States)

    Arola, A.; Eck, T. F.; Huttunen, J.; Lehtinen, K. E. J.; Lindfors, A. V.; Myhre, G.; Smirinov, A.; Tripathi, S. N.; Yu, H.

    2013-01-01

    The diurnal variability of aerosol optical depth (AOD) can be significant, depending on location and dominant aerosol type. However, these diurnal cycles have rarely been taken into account in measurement-based estimates of aerosol direct radiative forcing (ADRF) or aerosol direct radiative effect (ADRE). The objective of our study was to estimate the influence of diurnal aerosol variability at the top of the atmosphere ADRE estimates. By including all the possible AERONET sites, we wanted to assess the influence on global ADRE estimates. While focusing also in more detail on some selected sites of strongest impact, our goal was to also see the possible impact regionally.We calculated ADRE with different assumptions about the daily AOD variability: taking the observed daily AOD cycle into account and assuming diurnally constant AOD. Moreover, we estimated the corresponding differences in ADREs, if the single AOD value for the daily mean was taken from the the Moderate Resolution Imaging Spectroradiometer (MODIS) Terra or Aqua overpass times, instead of accounting for the true observed daily variability. The mean impact of diurnal AOD variability on 24 h ADRE estimates, averaged over all AERONET sites, was rather small and it was relatively small even for the cases when AOD was chosen to correspond to the Terra or Aqua overpass time. This was true on average over all AERONET sites, while clearly there can be much stronger impact in individual sites. Examples of some selected sites demonstrated that the strongest observed AOD variability (the strongest morning afternoon contrast) does not typically result in a significant impact on 24 h ADRE. In those cases, the morning and afternoon AOD patterns are opposite and thus the impact on 24 h ADRE, when integrated over all solar zenith angles, is reduced. The most significant effect on daily ADRE was induced by AOD cycles with either maximum or minimum AOD close to local noon. In these cases, the impact on 24 h ADRE was

  15. The role of boundary layer dynamics on the diurnal evolution of isoprene and the hydroxyl radical over tropical forests

    NARCIS (Netherlands)

    Vilà-Guerau de Arellano, J.; Patton, E.G.; Karl, T.; Dries, van den K.; Barth, M.C.; Orlando, J.J.

    2011-01-01

    We investigate diurnal variability of isoprene and related chemical species in the Amazonian region. The dynamics and chemistry of an atmospheric boundary layer are studied with a large-eddy simulation code and a mixed-layer model which are guided by observations available for the same area. The mai

  16. Water stress induced breakdown of carbon-water relations: indicators from diurnal FLUXNET patterns

    Science.gov (United States)

    Nelson, Jacob; Carvalhais, Nuno; Migliavacca, Mirco; Reichstein, Markus; Jung, Martin

    2017-04-01

    Understanding of terrestrial carbon and water cycles is currently hampered by an uncertainty in how to capture the large variety of plant responses to drought across climates, ecological strategies, and environments. In FLUXNET, many sites do not uniformly report the ancillary variables needed to study drought response physiology such as soil moisture, sap flux, or species composition. In this sense, the use of diurnal patters to derive clues on ecosystem water limitation responses at a daily resolution from an existing dataset could prove valuable, if nothing less than a benchmark to test current hypotheses. To this end, we propose two data-driven indicators derived directly from the eddy covariance data and based on expected physiological responses to hydraulic and non-stomatal limitations. Hydraulic limitations are proxied using the normalized diurnal centroid, which measures the degree to which the flux of ET is shifted toward the morning. Non-stomatal limitations are characterized by the Diurnal Water:Carbon Index (DWCI), which measures the degree of coupling between daily ET and GPP fluxes. Globally, we found significantly high frequencies of morning shifted days in dry/Mediterranean climates and savanna plant functional types (PFT), whereas high frequencies of decoupling were found in dry climates and grassland/savanna PFTs. Overall, both the diurnal centroid and DWCI were associated with high net radiation and low latent energy. Using three water use efficiency (WUE) models, we found the mean difference between expected and observed WUE to be 0.09 to -0.23 umol/mmol and -0.42 to -0.49 umol/mmol for decoupled and morning shifted days respectively, indicating an increase in WUE associated with the metrics that the models were unable to capture. Furthermore we discuss the application of diurnal centroid and DWCI to methods of evapotranspiration partitioning and estimation of ecosystem isohydricity.

  17. Combined diurnal variations of discharge and hydrochemistry of the Isunnguata Sermia outlet, Greenland Ice Sheet

    Science.gov (United States)

    Graly, Joseph; Harrington, Joel; Humphrey, Neil

    2017-05-01

    In order to examine daily cycles in meltwater routing and storage in the Isunnguata Sermia outlet of the Greenland Ice Sheet, variations in outlet stream discharge and in major element hydrochemistry were assessed over a 6-day period in July 2013. Over 4 days, discharge was assessed from hourly photography of the outlet from multiple vantages, including where midstream naled ice provided a natural gauge. pH, electrical conductivity, suspended sediment, and major element and anion chemistry were measured in samples of stream water collected every 3 h.Photography and stream observations reveal that although river width and stage have only slight diurnal variation, there are large diurnal changes in discharge shown by the doubling in width of what we term the active channel, which is characterized by large standing waves and fast flow. The concentration of dissolved solutes follows a sinusoidal diurnal cycle, except for large and variable increases in dissolved solutes during the stream's waning flow. Solute concentrations vary by ˜ 30 % between diurnal minima and maxima. Discharge maxima and minima lag temperature and surface melt by 3-7 h; diurnal solute concentration minima and maxima lag discharge by 3-6 h.This phase shift between discharge and solute concentration suggests that during high flow, water is either encountering more rock material or is stored in longer contact with rock material. We suggest that expansion of a distributed subglacial hydrologic network into seldom accessed regions during high flow could account for these phenomena, and for a spike of partial silicate reaction products during waning flow, which itself suggests a pressure threshold-triggered release of stored water.

  18. A Machine Learning Method to Infer Fundamental Stellar Parameters from Photometric Light Curves

    CERN Document Server

    Miller, A A; Richards, J W; Lee, Y S; Starr, D L; Butler, N R; Tokarz, S; Smith, N; Eisner, J A

    2014-01-01

    A fundamental challenge for wide-field imaging surveys is obtaining follow-up spectroscopic observations: there are > $10^9$ photometrically cataloged sources, yet modern spectroscopic surveys are limited to ~few x $10^6$ targets. As we approach the Large Synoptic Survey Telescope (LSST) era, new algorithmic solutions are required to cope with the data deluge. Here we report the development of a machine-learning framework capable of inferring fundamental stellar parameters (Teff, log g, and [Fe/H]) using photometric-brightness variations and color alone. A training set is constructed from a systematic spectroscopic survey of variables with Hectospec/MMT. In sum, the training set includes ~9000 spectra, for which stellar parameters are measured using the SEGUE Stellar Parameters Pipeline (SSPP). We employed the random forest algorithm to perform a non-parametric regression that predicts Teff, log g, and [Fe/H] from photometric time-domain observations. Our final, optimized model produces a cross-validated root...

  19. Dissecting Photometric redshift for Active Galactic Nuclei using XMM- and Chandra-COSMOS samples

    CERN Document Server

    Salvato, M; Hasinger, G; Rau, A; Civano, F; Zamorani, G; Brusa, M; Elvis, M; Vignali, C; Aussel, H; Comastri, A; Fiore, F; Floc'h, E Le; Mainieri, V; Bardelli, S; Bolzonella, M; Bongiorno, A; Capak, P; Caputi, K; Cappelluti, N; Carollo, C M; Contini, T; Garilli, B; Iovino, A; Fotopoulou, S; Fruscione, A; Gilli, R; Halliday, C; Kneib, J-P; Kakazu, Y; Kartaltepe, J S; Koekemoer, A M; Kovac, K; Ideue, Y; Ikeda, H; Impey, C D; Fevre, O Le; Lamareille, F; Lanzuisi, G; Borgne, J-F Le; Brun, V Le; Lilly, S J; Maier, C; Manohar, S; Masters, D; McCracken, H; Messias, H; Mignoli, M; Mobasher, B; Nagao, T; Pello, R; Puccetti, S; Renzini, E Perez Montero A; Sargent, M; Sanders, D B; Scodeggio, M; Scoville, N; Shopbell, P; Silvermann, J; Taniguchi, Y; Tasca, L; Tresse, L; Trump, J R; Zucca, E

    2011-01-01

    With this paper, we release accurate photometric redshifts for 1692 counterparts to Chandra sources in the central square degree of the COSMOS field. The availability of a large training set of spectroscopic redshifts that extends to faint magnitudes enabled photometric redshifts comparable to the highest quality results presently available for normal galaxies. We demonstrate that morphologically extended, faint X-ray sources without optical variability are more accurately described by a library of normal galaxies (corrected for emission lines) than by AGN-dominated templates, even if these sources have AGN-like X-ray luminosities. Preselecting the library on the bases of the source properties allowed us to reach an accuracy sigma_(Delta z/(1+z_spec)) \\sim0.015 with a fraction of outliers of 5.8% for the entire Chandra-COSMOS sample. In addition, we release revised photometric redshifts for the 1735 optical counterparts of the XMM-detected sources over the entire 2 sq. deg.of COSMOS. For 248 sources, our upda...

  20. Spectro-photometric characterization of high proper motion sources from WISE

    CERN Document Server

    Beamín, J C; Minniti, D; Smart, R L; Muzic, K; Mendez, R A; Beletsky, Y; Bayo, A; Gromadzki, M; Kurtev, R

    2015-01-01

    The census of the solar neighborhood is almost complete for stars and becoming more complete in the brown dwarf regime. Spectroscopic, photometric and kinematic characterization of nearby objects helps us to understand the local mass function, the binary fraction, and provides new targets for sensitive planet searches. We aim to derive spectral types and spectro-photometric distances of a sample of new high proper motion sources found with the WISE satellite, and obtain parallaxes for those objects that fall within the area observed by the Vista Variables in the V\\'ia L\\'actea survey (VVV). We used low resolution spectroscopy and template fitting to derive spectral types, multiwavelength photometry to characterize the companion candidates and obtain photometric distances. Multi-epoch imaging from the VVV survey was used to measure the parallaxes and proper motions for three sources. We confirm a new T2 brown dwarf within $\\sim$15 pc. We derived optical spectral types for twenty four sources, mostly M dwarfs w...

  1. Homogeneous Photometry for Star Clusters and Resolved Galaxies; 2, Photometric Standard Stars

    CERN Document Server

    Stetson, P B

    2000-01-01

    Stars appearing in CCD images obtained over 224 nights during the course of 69 observing runs have been calibrated to the Johnson/Kron-Cousins BVRI photometric system defined by the equatorial standards of Landolt (1992, AJ, 104, 340). More than 15,000 stars suitable for use as photometric standards have been identified, where "suitable" means that the star has been observed five or more times during photometric conditions and has a standard error of the mean magnitude less than 0.02 mag in at least two of the four bandpasses, and shows no significant evidence of intrinsic variability. Many of these stars are in the same fields as Landolt's equatorial standards or Graham's (1982, PASP, 94, 244) southern E-region standards, but are considerably fainter. This enhances the value of those fields for the calibration of photometry obtained with large telescopes. Other standards have been defined in fields containing popular objects of astrophysical interest, such as star clusters and famous galaxies, extending Land...

  2. A photometricity and extinction monitor at the Apache Point Observatory

    CERN Document Server

    Hogg, D W; Schlegel, D J; Gunn, J E; Hogg, David W.; Finkbeiner, Douglas P.; Schlegel, David J.; Gunn, James E.

    2001-01-01

    An unsupervised software ``robot'' that automatically and robustly reduces and analyzes CCD observations of photometric standard stars is described. The robot measures extinction coefficients and other photometric parameters in real time and, more carefully, on the next day. It also reduces and analyzes data from an all-sky $10 \\mu m$ camera to detect clouds; photometric data taken during cloudy periods are automatically rejected. The robot reports its findings back to observers and data analysts via the World-Wide Web. It can be used to assess photometricity, and to build data on site conditions. The robot's automated and uniform site monitoring represents a minimum standard for any observing site with queue scheduling, a public data archive, or likely participation in any future National Virtual Observatory.

  3. AR Ser: photometric observations of a Blazhko star

    Science.gov (United States)

    Bonnardeau, Michel; Hambsch, Franz-Josef

    2015-02-01

    Photometric observations in 2010-2014 of the RR Lyrae star AR Serpentis are presented and analysed. Two Blazhko modulations of comparable amplitude are detected, with the periods 89 and 108 days, and with evidence for irregularities.

  4. Energetic constraints to chemo-photometric evolution of spiral galaxies

    CERN Document Server

    Buzzoni, Alberto

    2011-01-01

    The problem of chemo-photometric evolution of late-type galaxies is dealt with relying on prime physical arguments of energetic self-consistency between chemical enhancement of galaxy mass, through nuclear processing inside stars, and luminosity evolution of the system. Chemical enhancement is assessed in terms of the so-called "yield metallicity", that is the metal abundance of processed mass inside stars, as constrained by the galaxy photometric history.

  5. Photometric Compliance of Tablet Screens and Retro-Illuminated Acuity Charts As Visual Acuity Measurement Devices.

    Directory of Open Access Journals (Sweden)

    I A T Livingstone

    Full Text Available Mobile technology is increasingly used to measure visual acuity. Standards for chart-based acuity tests specify photometric requirements for luminance, optotype contrast and luminance uniformity. Manufacturers provide some photometric data but little is known about tablet performance for visual acuity testing. This study photometrically characterised seven tablet computers (iPad, Apple inc. and three ETDRS (Early Treatment Diabetic Retinopathy Study visual acuity charts with room lights on and off, and compared findings with visual acuity measurement standards. Tablet screen luminance and contrast were measured using nine points across a black and white checkerboard test screen at five arbitrary brightness levels. ETDRS optotypes and adjacent white background luminance and contrast were measured. All seven tablets (room lights off exceeded the most stringent requirement for mean luminance (≥ 120 cd/m2 providing the nominal brightness setting was above 50%. All exceeded contrast requirement (Weber ≥ 90% regardless of brightness setting, and five were marginally below the required luminance uniformity threshold (Lmin/Lmax ≥ 80%. Re-assessing three tablets with room lights on made little difference to mean luminance or contrast, and improved luminance uniformity to exceed the threshold. The three EDTRS charts (room lights off had adequate mean luminance (≥ 120 cd/m2 and Weber contrast (≥ 90%, but all three charts failed to meet the luminance uniformity standard (Lmin/Lmax ≥ 80%. Two charts were operating beyond manufacturer's recommended lamp replacement schedule. With room lights on, chart mean luminance and Weber contrast increased, but two charts still had inadequate luminance uniformity. Tablet computers showed less inter-device variability, higher contrast, and better luminance uniformity than charts in both lights-on and lights-off environments, providing brightness setting was >50%. Overall, iPad tablets matched or marginally out

  6. Understanding the influence of orography on the precipitation diurnal cycle and the associated atmospheric processes in the central Andes

    Science.gov (United States)

    Junquas, C.; Takahashi, K.; Condom, T.; Espinoza, J.-C.; Chavez, S.; Sicart, J.-E.; Lebel, T.

    2017-08-01

    In the tropical Andes, the identification of the present synoptic mechanisms associated with the diurnal cycle of precipitation and its interaction with orography is a key step to understand how the atmospheric circulation influences the patterns of precipitation variability on longer time-scales. In particular we aim to better understand the combination of the local and regional mechanisms controlling the diurnal cycle of summertime (DJF) precipitation in the Northern Central Andes (NCA) region of Southern Peru. A climatology of the diurnal cycle is obtained from 15 wet seasons (2000-2014) of 3-hourly TRMM-3B42 data (0.25° × 0.25°) and swath data from the TRMM-2A25 precipitation radar product (5 km × 5 km). The main findings are: (1) in the NCA region, the diurnal cycle shows a maximum precipitation occurring during the day (night) in the western (eastern) side of the Andes highlands, (2) in the valleys of the Cuzco region and in the Amazon slope of the Andes the maximum (minimum) precipitation occurs during the night (day). The WRF (Weather Research and Forecasting) regional atmospheric model is used to simulate the mean diurnal cycle in the NCA region for the same period at 27 km and 9 km horizontal grid spacing and 3-hourly output, and at 3 km only for the month of January 2010 in the Cuzco valleys. Sensitivity experiments were also performed to investigate the effect of the topography on the observed rainfall patterns. The model reproduces the main diurnal precipitation features. The main atmospheric processes identified are: (1) the presence of a regional-scale cyclonic circulation strengthening during the afternoon, (2) diurnal thermally driven circulations at local scale, including upslope (downslope) wind and moisture transport during the day (night), (3) channelization of the upslope moisture transport from the Amazon along the Apurimac valleys toward the western part of the cordillera.

  7. Photometric followup investigations on LAMOST survey target Ly And

    Science.gov (United States)

    Lu, Hong-peng; Zhang, Li-yun; Han, Xianming L.; Pi, Qing-feng; Wang, Dai-mei

    2017-02-01

    We present a low-dispersion spectrum and two sets of CCD photometric light curves of the eclipsing binary LY And for the first time. The spectrum of LY And was classified as G2. We derived an updated ephemeris based on all previously available and our newly acquired minimum light times. Our analyses of LY And light curve minimum times reveals that the differences between calculated and observed minimum times for LY And can be represented by an upward parabolic curve, which means its orbital period is increasing with a rate of 1.88 (± 0.13) × 10-7 days/year. This increase in orbital period may be interpreted as mass transfer from the primary component to the secondary component, with a rate of dM1/dt = -4.54 × 10-8M⊙/year. By analyzing our CCD photometric light curves obtained in 2015, we obtained its photometric solution with the Wilson-Devinney program. This photometric solution also fits very well our light curves obtained in 2014. Our photometric solution shows that LY And is a contact eclipsing binary and its contact factor is f = (17.8 ± 1.9)%. Furthermore, both our spectroscopic and photometric data show no obvious chromospheric activity of LY And.

  8. Improved Photometric Calibrations for Red Stars Observed with the SDSS Photometric Telescope

    CERN Document Server

    Davenport, James R A; Covey, Kevin R; Hawley, Suzanne L; West, Andrew A; Schneider, Donald P

    2007-01-01

    We present a new set of photometric transformations for red stars observed with the Sloan Digital Sky Survey (SDSS) 0.5-m Photometric Telescope (PT) and the SDSS 2.5-m telescope at the Apache Point Observatory in New Mexico. Nightly PT observations of US Naval Observatory standards are used to determine extinction corrections and calibration terms for SDSS 2.5-m photometry. Systematic differences between the PT and native SDSS 2.5-m {\\it ugriz} photometry require conversions between the two systems which have previously been undefined for the reddest stars. By matching $\\sim 43,000$ stars observed with both the PT and SDSS 2.5-m, we extend the present relations to include low-mass stars with colors $0.6 \\le r-i \\le 1.7$. These corrections will allow us to place photometry of bright, low-mass trigonometric parallax stars previously observed with the PT on the 2.5-m system. We present new transformation equations and discuss applications of these data to future low-mass star studies using the SDSS.

  9. Children's Diurnal Cortisol Activity during the First Year of School

    Science.gov (United States)

    Yang, Pei-Jung; Lamb, Michael E.; Kappler, Gregor; Ahnert, Lieselotte

    2017-01-01

    The present study examined 4- to 5-year-old British children's diurnal cortisol activity during their first year of school. The children's cortisol was measured before enrollment (baseline), upon enrollment, and both 3 and 6 months after enrollment. On each day, cortisol was sampled four times, providing information about the diurnal amount of…

  10. Children's Diurnal Cortisol Activity during the First Year of School

    Science.gov (United States)

    Yang, Pei-Jung; Lamb, Michael E.; Kappler, Gregor; Ahnert, Lieselotte

    2017-01-01

    The present study examined 4- to 5-year-old British children's diurnal cortisol activity during their first year of school. The children's cortisol was measured before enrollment (baseline), upon enrollment, and both 3 and 6 months after enrollment. On each day, cortisol was sampled four times, providing information about the diurnal amount of…

  11. Diurnal cycle of the dust instantaneous direct radiative forcing over the Arabian Peninsula

    KAUST Repository

    Osipov, S.

    2015-08-27

    In this study we attempted to better quantify radiative effects of dust over the Arabian Peninsula and their dependence on input parameters. For this purpose we have developed a stand-alone column radiation transport model coupled with the Mie, T-matrix and geometric optics calculations and driven by reanalysis meteorological fields and atmospheric composition. Numerical experiments were carried out for a wide range of aerosol optical depths, including extreme values developed during the dust storm on 18–20 March 2012. Comprehensive ground-based observations and satellite retrievals were used to estimate aerosol optical properties, validate calculations and carry out radiation closure. The broadband surface albedo, fluxes at the bottom and top of the atmosphere as well as instantaneous dust radiative forcing were estimated both from the model and observations. Diurnal cycle of the shortwave instantaneous dust direct radiative forcing was studied for a range of aerosol and surface characteristics representative of the Arabian Peninsula. Mechanisms and parameters responsible for diurnal variability of the radiative forcing were evaluated. We found that intrinsic variability of the surface albedo and its dependence on atmospheric conditions, along with anisotropic aerosol scattering, are mostly responsible for diurnal effects.

  12. Quantifying Diurnal Cloud Radiative Effects by Cloud Type in the Tropical Western Pacific

    Energy Technology Data Exchange (ETDEWEB)

    Burleyson, Casey D.; Long, Charles N.; Comstock, Jennifer M.

    2015-06-01

    Cloud radiative effects are examined using long-term datasets collected at the three Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facilities in the tropical western Pacific. We quantify the surface radiation budget, cloud populations, and cloud radiative effects by partitioning the data by cloud type, time of day, and as a function of large scale modes of variability such as El Niño Southern Oscillation (ENSO) phase and wet/dry seasons at Darwin. The novel facet of our analysis is that we break aggregate cloud radiative effects down by cloud type across the diurnal cycle. The Nauru cloud populations and subsequently the surface radiation budget are strongly impacted by ENSO variability whereas the cloud populations over Manus only shift slightly in response to changes in ENSO phase. The Darwin site exhibits large seasonal monsoon related variations. We show that while deeper convective clouds have a strong conditional influence on the radiation reaching the surface, their limited frequency reduces their aggregate radiative impact. The largest source of shortwave cloud radiative effects at all three sites comes from low clouds. We use the observations to demonstrate that potential model biases in the amplitude of the diurnal cycle and mean cloud frequency would lead to larger errors in the surface energy budget compared to biases in the timing of the diurnal cycle of cloud frequency. Our results provide solid benchmarks to evaluate model simulations of cloud radiative effects in the tropics.

  13. Analysis of the Diurnal Pattern of Evaporative Fraction and Its Controlling Factors over Croplands in the Northern China

    Institute of Scientific and Technical Information of China (English)

    YANG Da-wen; CHEN He; LEI Hui-min

    2013-01-01

    A key issue of applying remotely sensed data to estimate evapotranspiration (ET) for water management is extrapolating instantaneous latent heat flux (LE) at satellite over-passing time to daily ET total. At present, the most commonly used extrapolation methods have the same assumption that evaporative fraction (EF) can be treated as constant during daytime (so-called EF self-preservation). However, large errors are reported by many documents over various ecosystems with the same approach, which indicates that further analysis of the diurnal pattern of EF is still necessary. The aim of this study is to examine the diurnal pattern of EF under fair weather conditions, then to analyze the dependencies of EF to meteorological and plant factors. Long-term flux observations at four sites over semi-arid and semi-humid climate regions in the northern China are used to analyze the EF diurnal pattern. Results show that the EF self-preservation assumption no longer holds over growing seasons of crops. However, the ratio of reference ET to available energy is almost constant during the daytime, which implies the climate factors do not have much effect on the variability of EF. The analysis of diurnal pattern of air temperature, vapor pressure deficiency (VPD), and relative humidity (RH) confirms the assumption that ET diurnal pattern is mainly influenced by stomatal regulation.

  14. On Tidal Inference in the Diurnal Band

    Science.gov (United States)

    Ray, R. D.

    2017-01-01

    Standard methods of tidal inference should be revised to account for a known resonance that occurs mostly within the K(sub 1) tidal group in the diurnal band. The resonance arises from a free rotational mode of Earth caused by the fluid core. In a set of 110 bottom-pressure tide stations, the amplitude of the P(sub 1) tidal constituent is shown to be suppressed relative to K(sub 1), which is in good agreement with the resonance theory. Standard formulas for the K(sub 1) nodal modulation remain essentially unaffected. Two examples are given of applications of the refined inference methodology: one with monthly tide gauge data and one with satellite altimetry. For some altimeter-constrained tide models, an inferred P(sub 1) constituent is found to be more accurate than a directly determined one.

  15. Diurnal Emotional States Impact the Sleep Course.

    Directory of Open Access Journals (Sweden)

    Julien Delannoy

    Full Text Available Diurnal emotional experiences seem to affect several characteristics of sleep architecture. However, this influence remains unclear, especially for positive emotions. In addition, electrodermal activity (EDA, a sympathetic robust indicator of emotional arousal, differs depending on the sleep stage. The present research has a double aim: to identify the specific effects of pre-sleep emotional states on the architecture of the subsequent sleep period; to relate such states to the sympathetic activation during the same sleep period.Twelve healthy volunteers (20.1 ± 1.0 yo. participated in the experiment and each one slept 9 nights at the laboratory, divided into 3 sessions, one per week. Each session was organized over three nights. A reference night, allowing baseline pre-sleep and sleep recordings, preceded an experimental night before which participants watched a negative, neutral, or positive movie. The third and last night was devoted to analyzing the potential recovery or persistence of emotional effects induced before the experimental night. Standard polysomnography and EDA were recorded during all the nights.Firstly, we found that experimental pre-sleep emotional induction increased the Rapid Eye Movement (REM sleep rate following both negative and positive movies. While this increase was spread over the whole night for positive induction, it was limited to the second half of the sleep period for negative induction. Secondly, the valence of the pre-sleep movie also impacted the sympathetic activation during Non-REM stage 3 sleep, which increased after negative induction and decreased after positive induction.Pre-sleep controlled emotional states impacted the subsequent REM sleep rate and modulated the sympathetic activity during the sleep period. The outcomes of this study offer interesting perspectives related to the effect of diurnal emotional influences on sleep regulation and open new avenues for potential practices designed to

  16. Differences in the mean wind and its diurnal variation between wet and dry spells of the monsoon over southeast India

    Science.gov (United States)

    Mohan, T. S.; Rao, T. N.

    2016-06-01

    The differences in the vertical structure of mean wind and its diurnal variation from the surface to upper troposphere between wet and dry spells are studied using a unique data set consisting of surface and remote sensing (SOund Detection and Ranging and wind profilers) measurements made at Gadanki (13.5°N 79.2°E). Special emphasis was given to study the variation of low-level jet (LLJ) and tropical easterly jet (TEJ), two most conspicuous features of the Indian summer monsoon. Largest and significant wind differences between the spells are observed in the lower troposphere (spell than during wet spell. The spatial variation of LLJ and TEJ depicts intriguing differences between the spells. The LLJ splits into two branches over the Arabian Sea during the dry spell, while only one branch is apparent during the wet spell. On the 100 hPa level, the longitudinal extent of the TEJ is larger during the dry spell than during wet spell. The vertical variation (in particular, in the lower troposphere) of the amplitude and phase of diurnal cycle is significant and, to some extent, different during the dry and wet spells. The plausible mechanisms responsible for the change in the phase of the diurnal cycle with altitude are discussed. The amplitude of the diurnal cycle increases with altitude up to 2 km and then decreases. Largest amplitudes in the entire troposphere and lower stratosphere are found in the height region of 1-2 km. Given that LLJ peak magnitude and height exhibit a strong diurnal variation, one should be careful in obtaining characteristics of the LLJ and nocturnal LLJ from observations made at a fixed time. The diurnal variation of LLJ and TEJ exhibits distinct spatial variability in both spells. The results are compared and contrasted with earlier reports on intraseasonal variability of the LLJ and TEJ.

  17. A One-Year Study of the Diurnal Cycle of Meteorology, Clouds, and Radiation in the West African Sahel Region

    Energy Technology Data Exchange (ETDEWEB)

    Marquardt-Collow, Allison; Ghate, Virendra P.; Miller, Mark A.; Trabachino, Lynne

    2016-01-09

    The diurnal cycles of meteorological and radiation variables are analyzed during the wet and dry seasons over the Sahel region of West Africa during 2006 using surface data collected by the Atmospheric Radiation Measurement (ARM) program’s Mobile Facility, satellite radiation measurements from the Geostationary Earth Radiation Budget (GERB) instrument aboard Meteosat 8, and reanalysis products from the National Center for Environmental Prediction (NCEP). The meteorological analysis builds upon past studies of the diurnal cycle in the region by incorporating diurnal cycles of lower tropospheric wind profiles, thermodynamic profiles, integrated water vapor and liquid water measurements, and cloud radar measurements of frequency and location. These meteorological measurements are complemented by 3-hour measurements of the diurnal cycles of the TOA and surface shortwave (SW) and longwave (LW) radiative fluxes and cloud radiative effects (CREs), and the atmospheric radiative flux divergence (RFD) and atmospheric CREs. Cirrus cloudiness during the dry season is shown to peak in coverage in the afternoon, while convective clouds during the wet season are shown to peak near dawn and have an afternoon minimum related to the rise of the Lifting Condensation Level into the Saharan Air Layer. The LW and SW RFDs and CREs exhibit diurnal cycles during both seasons, but there is a relatively small difference in the LW cycles during the two seasons (10-30 Wm^(-2) depending on the variable and time of day). Small differences in the TOA CREs during the two seasons are overwhelmed by large differences in the surface SW CREs, which exceed 100 Wm^(-2). A significant surface SW CRE during the wet season combined with a negligible TOA SW CRE produces a diurnal cycle in the atmospheric CRE that is modulated primarily by the SW surface CRE, peaks at midday at ~150 Wm^(-2), and varies widely from day to day.

  18. Photometric Monitoring of Active Galactic Nuclei in the Center for Automated Space Science: Preliminary Results

    Science.gov (United States)

    Culler, Ryan; Deckard, Monica; Guilaran, Fonsie; Watson, Casey; Carini, Michael; Gelderman, Richard; Neely, William

    1997-02-01

    In this paper, we will present preliminary results of our program to photometrically monitor a set of Active Galactic Nuclei (AGN) known as Blazars. Using CCDs as N-star photometers and a technique known as aperture photometry, we can achieve close to 0.02 magnitude precision with small to midsize telescopes. Blazars are highly luminous and highly variable; studying these variations provides insight into the central engines producing the high luminosities. we report on our reduction and analysis of CCD data obtained at one of our collaborating institutions, the NF Observatory at Western New Mexico University. CCD data obtained at the Western Kentucky University 24 inch telescope will also be discussed.

  19. On the influence of the diurnal variations of aerosol content to estimate direct aerosol radiative forcing using MODIS data

    Science.gov (United States)

    Xu, Hui; Guo, Jianping; Ceamanos, Xavier; Roujean, Jean-Louis; Min, Min; Carrer, Dominique

    2016-09-01

    Long-term measurements of aerosol optical depth (AOD) from the Aerosol Robotic Network (AERONET) located in Beijing reveal a strong diurnal cycle of aerosol load staged by seasonal patterns. Such pronounced variability is matter of importance in respect to the estimation of daily averaged direct aerosol radiative forcing (DARF). Polar-orbiting satellites could only offer a daily revisit, which turns in fact to be even much less in case of frequent cloudiness. Indeed, this places a severe limit to properly capture the diurnal variations of AOD and thus estimate daily DARF. Bearing this in mind, the objective of the present study is however to evaluate the impact of AOD diurnal variations for conducting quantitative assessment of DARF using Moderate Resolution Imaging Spectroradiometer (MODIS) AOD data over Beijing. We provide assessments of DARF with two different assumptions about diurnal AOD variability: taking the observed hourly-averaged AOD cycle into account and assuming constant MODIS (including Terra and Aqua) AOD value throughout the daytime. Due to the AOD diurnal variability, the absolute differences in annual daily mean DARFs, if the constant MODIS/Terra (MODIS/Aqua) AOD value is used instead of accounting for the observed hourly-averaged daily variability, is 1.2 (1.3) Wm-2 at the top of the atmosphere, 27.5 (30.6) Wm-2 at the surface, and 26.4 (29.3) Wm-2 in the atmosphere, respectively. During the summertime, the impact of the diurnal AOD variability on seasonal daily mean DARF estimates using MODIS Terra (Aqua) data can reach up to 2.2 (3.9) Wm-2 at the top of the atmosphere, 43.7 (72.7) Wm-2 at the surface, and 41.4 (68.8) Wm-2 in the atmosphere, respectively. Overall, the diurnal variation in AOD tends to cause large bias in the estimated DARF on both seasonal and annual scales. In summertime, the higher the surface albedo, the stronger impact on DARF at the top of the atmosphere caused by dust and biomass burning (continental) aerosol. This

  20. Photometric calibrations for 21st century science

    Energy Technology Data Exchange (ETDEWEB)

    Kent, Stephen; /Fermilab; Kaiser, Mary Elizabeth; /Johns Hopkins U.; Deustua, Susana E.; /Baltimore, Space Telescope Sci.; Smith, J.Allyn; /Austin Peay State U.; Adelman, Saul; /Citadel Military Coll.; Allam, Sahar S.; /Fermilab; Baptista, Brian; /Indiana U.; Bohlin, Ralph C.; /Baltimore, Space Telescope Sci.; Clem, James L.; /Louisiana State U.; Conley, Alex; /Colorado U.; Edelstein, Jerry; /UC, Berkeley, Space Sci. Dept. /NOAO, Tucson

    2009-02-01

    The answers to fundamental science questions in astrophysics, ranging from the history of the expansion of the universe to the sizes of nearby stars, hinge on our ability to make precise measurements of diverse astronomical objects. As our knowledge of the underlying physics of objects improves along with advances in detectors and instrumentation, the limits on our capability to extract science from measurements is set, not by our lack of understanding of the nature of these objects, but rather by the most mundane of all issues: the precision with which we can calibrate observations in physical units. In principle, photometric calibration is a solved problem - laboratory reference standards such as blackbody furnaces achieve precisions well in excess of those needed for astrophysics. In practice, however, transferring the calibration from these laboratory standards to astronomical objects of interest is far from trivial - the transfer must reach outside the atmosphere, extend over 4{pi} steradians of sky, cover a wide range of wavelengths, and span an enormous dynamic range in intensity. Virtually all spectrophotometric observations today are calibrated against one or more stellar reference sources, such as Vega, which are themselves tied back to laboratory standards in a variety of ways. This system's accuracy is not uniform. Selected regions of the electromagnetic spectrum are calibrated extremely well, but discontinuities of a few percent still exist, e.g., between the optical and infrared. Independently, model stellar atmospheres are used to calibrate the spectra of selected white dwarf stars, e.g. the HST system, but the ultimate accuracy of this system should be verified against laboratory sources. Our traditional standard star systems, while sufficient until now, need to be improved and extended in order to serve future astrophysics experiments. This white paper calls for a program to improve upon and expand the current networks of

  1. Photometric redshifts for the SDSS Data Release 12

    Science.gov (United States)

    Beck, Róbert; Dobos, László; Budavári, Tamás; Szalay, Alexander S.; Csabai, István

    2016-08-01

    We present the methodology and data behind the photometric redshift data base of the Sloan Digital Sky Survey (SDSS) Data Release 12. We adopt a hybrid technique, empirically estimating the redshift via local regression on a spectroscopic training set, then fitting a spectrum template to obtain K-corrections and absolute magnitudes. The SDSS spectroscopic catalogue was augmented with data from other, publicly available spectroscopic surveys to mitigate target selection effects. The training set is comprised of 1976 978 galaxies, and extends up to redshift z ≈ 0.8, with a useful coverage of up to z ≈ 0.6. We provide photometric redshifts and realistic error estimates for the 208 474 076 galaxies of the SDSS primary photometric catalogue. We achieve an average bias of overline{Δ z_{norm}} = {5.84 × 10^{-5}}, a standard deviation of σ(Δznorm) = 0.0205, and a 3σ outlier rate of Po = 4.11 per cent when cross-validating on our training set. The published redshift error estimates and photometric error classes enable the selection of galaxies with high-quality photometric redshifts. We also provide a supplementary error map that allows additional, sophisticated filtering of the data.

  2. Photometric Calibration of the Supernova Legacy Survey Fields

    CERN Document Server

    Regnault, N; Guy, J; Sullivan, M; Cuillandre, J -C; Astier, P; Balland, C; Basa, S; Carlberg, R G; Fouchez, D; Hardin, D; Hook, I M; Howell, D A; Pain, R; Perrett, K; Pritchet, C J

    2009-01-01

    We present the photometric calibration of the Supernova Legacy Survey (SNLS) fields. The SNLS aims at measuring the distances to SNe Ia at (0.3photometric calibration of the survey dominates the systematic uncertainty of the key measurement of the survey, namely the dark energy equation of state. The photometric calibration of the SNLS requires obtaining a uniform response across the imager, calibrating the science field stars in each survey band (SDSS-like ugriz bands) with respect to standards with known flux in the same bands, and binding the calibration to the UBVRI Landolt standards used to calibrate the nearby SNe from the literature necessary to produce cosmological constraints. The spatial non-uniformities of the imager photometric response are mapped using dithered observations of dense stellar fields. Photometric zero-points against Landolt standards are obtained. The linearity o...

  3. Diurnal variation in gait characteristics and transition speed.

    Science.gov (United States)

    Bessot, Nicolas; Lericollais, Romain; Gauthier, Antoine; Sesboüé, Bruno; Bulla, Jan; Moussay, Sebastien

    2015-02-01

    The aim of this study was to investigate the effect of time-of-day on Preferred Transition Speed (PTS) and spatiotemporal organization of walking and running movements. Twelve active male subjects participated in the study (age: 27.2 ± 4.9 years; height: 177.9 ± 5.4 cm; body mass: 75.9 ± 5.86 kg). First, PTS was determined at 08:00 h and 18:00 h. The mean of the two PTS recorded at the two times-of-day tested was used as a reference (PTSm). Then, subjects were asked to walk and run on a treadmill at three imposed speeds (PTSm, PTSm + 0.3 m.s(-1), and PTSm - 0.3 m.s(-1)) at 08:00 h and 18:00 h. Mean stride length, temporal stride, spatial stride variability, and temporal stride variability were used for gait analysis. The PTS observed at 08:00 h (2.10 ± 0.17 m.s(-1)) tends to be lower (p = 0.077) than that recorded at 18:00 h (2.14 ± 0.19 m.s(-1)). Stride lengths recorded while walking (p = 0.038) and running (p = 0.041) were shorter at 08:00 h than 18:00 h. No time-of-day effect was observed for stride frequency during walking and running trials. When walking, spatial stride variability (p = 0.020) and temporal stride variability (p = 0.028) were lower at 08:00 h than at 18:00 h. When running, no diurnal variation of spatial stride variability or temporal stride variability was detected.

  4. Photometric magnetic-activity metrics tested with the Sun: application to Kepler M dwarfs

    Directory of Open Access Journals (Sweden)

    Mathur Savita

    2014-05-01

    Full Text Available The Kepler mission has been providing high-quality photometric data leading to many breakthroughs in the exoplanet search and in stellar physics. Stellar magnetic activity results from the interaction between rotation, convection, and magnetic field. Constraining these processes is important if we want to better understand stellar magnetic activity. Using the Sun, we want to test a magnetic activity index based on the analysis of the photometric response and then apply it to a sample of M dwarfs observed by Kepler. We estimate a global stellar magnetic activity index by measuring the standard deviation of the whole time series, Sph. Because stellar variability can be related to convection, pulsations or magnetism, we need to ensure that this index mostly takes into account magnetic effects. We define another stellar magnetic activity index as the average of the standard deviation of shorter subseries which lengths are determined by the rotation period of the star. This way we can ensure that the measured photometric variability is related to starspots crossing the visible stellar disc. This new index combined with a time-frequency analysis based on the Morlet wavelets allows us to determine the existence of magnetic activity cycles. We measure magnetic indexes for the Sun and for 34 M dwarfs observed by Kepler. As expected, we obtain that the sample of M dwarfs studied in this work is much more active than the Sun. Moreover, we find a small correlation between the rotation period and the magnetic index. Finally, by combining a time-frequency analysis with phase diagrams, we discover the presence of long-lived features suggesting the existence of active longitudes on the surface of these stars.

  5. Atmospheric boundary layer measurements at the 280 m high Hamburg weather mast 1995-2011. Mean annual and diurnal cycles

    Energy Technology Data Exchange (ETDEWEB)

    Bruemmer, Burghard; Lange, Ingo; Konow, Heike [Hamburg Univ. (Germany). Meteorologisches Inst.

    2012-08-15

    In this paper, the 280 m high Hamburg weather mast and its instrumentation are introduced. Digital data recorded since 1995 are used to calculate the mean annual and diurnal cycles of the primary climate variables (pressure, temperature, humidity, wind, short- and long-wave radiation, cloud coverage, cloud base, precipitation). The annual average of 2 m temperature is 9.8 C indicating an increase compared to the period 1971-2000 at the Hamburg airport climate station. Absolute humidity follows the temperature cycle with a maximum in July/August. Relative humidity is highest in winter and lowest in April/May. The fraction of received to clear-sky short-wave radiation is between 61 % in May and 34 % in December. Cloud coverage classes of 0-1 octas and 7-8 octas occur most frequently, but have opposite annual cycles. Cloud base distribution is narrow in winter and peaks around 300 m and is distributed over a wide height range in summer. Average annual precipitation amounts to 716 mm and falls in 9.3 % of the time. Monthly mean wind speed is highest (lowest) in January (August). Winds from west are most frequent followed by winds from southeast. A channelling by the Elbe river valley is indicated. The diurnal temperature cycle is weak in winter but strong in summer showing the evening generation and morning rise of the inversion. While relative humidity has a single diurnal cycle, absolute humidity has a double cycle in summer, but not in winter. Short-wave radiation in summer shows a weak asymmetry between forenoon and afternoon. The diurnal cycles of cloud cover and base are small in winter. In summer, cloud bases show a continuous increase from morning to afternoon and a break afterwards simultaneously with the diurnal rain maximum. Wind speed has opposite diurnal cycles at lower and upper levels. The upper-level cycle shows a temporal asymmetry in summer, i.e. the upper-level wind minimum does not occur simultaneously with the lower-level wind maximum. The reversal

  6. ELM-KNN for photometric redshift estimation of quasars

    Science.gov (United States)

    Zhang, Yanxia; Tu, Yang; Zhao, Yongheng; Tian, Haijun

    2017-06-01

    We explore photometric redshift estimation of quasars with the SDSS DR12 quasar sample. Firstly the quasar sample is separated into three parts according to different redshift ranges. Then three classifiers based on Extreme Learning Machine (ELM) are created in the three redshift ranges. Finally k-Nearest Neighbor (kNN) approach is applied on the three samples to predict photometric redshifts of quasars with multiwavelength photometric data. We compare the performance with different input patterns by ELM-KNN with that only by kNN. The experimental results show that ELM-KNN is feasible and superior to kNN (e.g. rms is 0.0751 vs. 0.2626 for SDSS sample), in other words, the ensemble method has the potential to increase regressor performance beyond the level reached by an individual regressor alone and will be a good choice when facing much more complex data.

  7. First photometric study of W UMa binary star LU Lac

    Science.gov (United States)

    Liao, W.-P.; Qian, S.-B.; Zhao, E.-G.; Jiang, L.-Q.

    2014-08-01

    LU Lac is a neglected W UMa binary star in photometric investigations. In this paper, we present BVRI CCD photometric light curves obtained on one night in 2012. The first photometric solutions of this system are computed by using the Wilson-Devinney code. It is shown that LU Lac is a marginal contact W-type system with a degree of contact factor of f=8.9%, a mass ratio of q=2.085 and a high inclination of i=82°.20. From the first analyses of orbital period changes, we found the period variation of the system includes an oscillation (A3=0.0125 days and T3=51.92 years). The cyclic change may be attributed to the light-travel time effect through the presence of a third body.

  8. Semi-supervised Learning for Photometric Supernova Classification

    CERN Document Server

    Richards, Joseph W; Freeman, Peter E; Schafer, Chad M; Poznanski, Dovi

    2011-01-01

    We present a semi-supervised method for photometric supernova typing. Our approach is to first use the nonlinear dimension reduction technique diffusion map to detect structure in a database of supernova light curves and subsequently employ random forest classification on a spectroscopically confirmed training set to learn a model that can predict the type of each newly observed supernova. We demonstrate that this is an effective method for supernova typing. As supernova numbers increase, our semi-supervised method efficiently utilizes this information to improve classification, a property not enjoyed by template based methods. Applied to supernova data simulated by Kessler et al. (2010b) to mimic those of the Dark Energy Survey, our methods achieve (cross-validated) 96% Type Ia purity and 86% Type Ia efficiency on the spectroscopic sample, but only 56% Type Ia purity and 48% efficiency on the photometric sample due to their spectroscopic followup strategy. To improve the performance on the photometric sample...

  9. METAPHOR: Probability density estimation for machine learning based photometric redshifts

    Science.gov (United States)

    Amaro, V.; Cavuoti, S.; Brescia, M.; Vellucci, C.; Tortora, C.; Longo, G.

    2017-06-01

    We present METAPHOR (Machine-learning Estimation Tool for Accurate PHOtometric Redshifts), a method able to provide a reliable PDF for photometric galaxy redshifts estimated through empirical techniques. METAPHOR is a modular workflow, mainly based on the MLPQNA neural network as internal engine to derive photometric galaxy redshifts, but giving the possibility to easily replace MLPQNA with any other method to predict photo-z's and their PDF. We present here the results about a validation test of the workflow on the galaxies from SDSS-DR9, showing also the universality of the method by replacing MLPQNA with KNN and Random Forest models. The validation test include also a comparison with the PDF's derived from a traditional SED template fitting method (Le Phare).

  10. Accurate photometric redshift probability density estimation - method comparison and application

    CERN Document Server

    Rau, Markus Michael; Brimioulle, Fabrice; Frank, Eibe; Friedrich, Oliver; Gruen, Daniel; Hoyle, Ben

    2015-01-01

    We introduce an ordinal classification algorithm for photometric redshift estimation, which vastly improves the reconstruction of photometric redshift probability density functions (PDFs) for individual galaxies and galaxy samples. As a use case we apply our method to CFHTLS galaxies. The ordinal classification algorithm treats distinct redshift bins as ordered values, which improves the quality of photometric redshift PDFs, compared with non-ordinal classification architectures. We also propose a new single value point estimate of the galaxy redshift, that can be used to estimate the full redshift PDF of a galaxy sample. This method is competitive in terms of accuracy with contemporary algorithms, which stack the full redshift PDFs of all galaxies in the sample, but requires orders of magnitudes less storage space. The methods described in this paper greatly improve the log-likelihood of individual object redshift PDFs, when compared with a popular Neural Network code (ANNz). In our use case, this improvemen...

  11. Improving Photometric Calibration of Meteor Video Camera Systems

    Science.gov (United States)

    Ehlert, Steven; Kingery, Aaron; Cooke, William

    2016-01-01

    Current optical observations of meteors are commonly limited by systematic uncertainties in photometric calibration at the level of approximately 0.5 mag or higher. Future improvements to meteor ablation models, luminous efficiency models, or emission spectra will hinge on new camera systems and techniques that significantly reduce calibration uncertainties and can reliably perform absolute photometric measurements of meteors. In this talk we discuss the algorithms and tests that NASA's Meteoroid Environment Office (MEO) has developed to better calibrate photometric measurements for the existing All-Sky and Wide-Field video camera networks as well as for a newly deployed four-camera system for measuring meteor colors in Johnson-Cousins BV RI filters. In particular we will emphasize how the MEO has been able to address two long-standing concerns with the traditional procedure, discussed in more detail below.

  12. Diurnal Cycle of Clouds and Precipitation at the ARM SGP Site

    Science.gov (United States)

    Zhao, W.; Marchand, R.; Fu, Q.

    2016-12-01

    Millimeter Wavelength Cloud Radar (MMCR) data from Dec. 1996 to Dec. 2010, collected at the U. S. Department of Energy Atmospheric Radiation Measurement (ARM) program site in the U.S. Southern Great Plains (SGP), are categorized into clouds (-40dBZe≤reflectivityCRM). Observational and simulated radar reflectivity are compared and further sorted into different atmospheric states identified by Evans (2014). Evans used a neutral network to take ERA-Interim state variables (i.e. horizontal winds, relative humidity, temperature at seven predetermined pressure level and surface pressure) on an 8×8 grid with 1.5º×1.5º spatial resolution centered on the SGP site and found twenty-one atmospheric states which represent specific synoptic conditions. We use these states to study the differences in the diurnal cycle between observations and simulations. Differences in the (mean) annual diurnal cycle between the observations and model are decomposed into errors in the daily mean, errors in the diurnal variation in each state, and errors due to difference in the frequency of occurrence of atmospheric states between ERA and the MMF. The magnitude of various error sources is assessed.

  13. Observed diurnal variation changes of Jakarta precipitation from 144 available meteorological records

    Science.gov (United States)

    Siswanto, Siswanto; van Oldenborgh, Geert Jan; van den Hurk, Bart; Jilderda, Rudmer

    2013-04-01

    Using a long available meteorological observation for almost 114 years hourly and daily record from Jakarta Observatory, the temporal heterogeneity of climate trends and its variability over Jakarta, Indonesia has been studied. The analyses showed that the number of wet days has decreased between 1880 and 2010, while the precipitation exceeding 50 mm is observed to be slightly increased. An increased trend of heavy rainfall in the 80% and 95% percentile between April and September was detected. Diurnal variation of Jakarta precipitation and temperature changed markedly. In the wet season (DJF), the morning rainfall has increased in intensity, while in other seasons; delayed amplitude of late afternoon rainfall peak is observed. The diurnal variation of night time temperature considerably increased while daytime temperature remains similar. Changes in temporal characteristics of light and heavy precipitation, as well as the diurnal variation of precipitation and temperature lead to hypotheses concerning anthropogenic influence. Some theoretical arguments on Urban Heat Island and aerosol effect precipitation could be linked to our results. Jakarta is a metropolitan city where its development is characterized by mixing of many different land uses and economic activities, including large-scale housing projects, industrial estates, and agricultural activities. In the future, the separation of local response to large scale and local changes will be investigated.

  14. Using sparse photometric data sets for asteroid lightcurve studies

    Science.gov (United States)

    Warner, Brian D.; Harris, Alan W.

    2011-12-01

    With the advent of wide-field imagers, it has become possible to conduct a photometric lightcurve survey of many asteroids simultaneously, either for that single purpose (e.g., Dermawan, B., Nakamura, T., Yoshida, F. [2011]. Publ. Astron. Soc. Japan 63, S555-S576; Masiero, J., Jedicke, R., Ďurech, J., Gwyn, S., Denneau, L., Larsen, J. [2009]. Icarus 204, 145-171), or as a part of a multipurpose survey (e.g., Pan-STARRS, LSST). Such surveys promise to yield photometric data for many thousands of asteroids, but these data sets will be “sparse” compared to most of those taken in a “targeted” mode directed to one asteroid at a time. We consider the potential limitations of sparse data sets using different sampling rates with respect to specific research questions that might be addressed with lightcurve data. For our study we created synthetic sparse data sets similar to those from wide-field surveys by generating more than 380,000 individual lightcurves that were combined into more than 47,000 composite lightcurves. The variables in generating the data included the number of observations per night, number of nights, noise, and the intervals between observations and nights, in addition to periods ranging from 0.1 to 400 h and amplitudes ranging from 0.1 to 2.0 mag. A Fourier analysis pipeline was used to find the period for each composite lightcurve and then review the derived period and period spectrum to gauge how well an automated analysis of sparse data sets would perform in finding the true period. For this part of the analysis, a normally distributed noise level of 0.03 mag was added to the data, regardless of amplitude, thus simulating a relatively high SNR for the observations. For the second part of the analysis, a smaller set of composite curves was generated with fixed core parameters of eight observations per night, 8 nights within a 14-day span, periods ranging from 2 to 6 h, and an amplitude of either 0.3 mag or 0.4 mag. Individual data sets using

  15. Diurnal Variation of Anterior Chamber Flare

    Directory of Open Access Journals (Sweden)

    Mehmet Adam

    2015-04-01

    Full Text Available Objectives: To investigate the ideal time and reproducibility of anterior chamber flare measurements. Materials and Methods: Anterior chamber flare measurements were performed with laser flaremetre device at 8 am to 45 volunteers and these measurements were repeated on the same day at 12 pm and 4 pm. Results: Twenty-five (55.5% of the volunteers were women and 20 (44.5% were men; mean age was 28.67±7.40 (18-49 years. The mean anterior chamber flare measurements taken following the ophthalmologic examination were 5.94±1.41 foton/msn at 8 am, 5.65±1.45 foton/msn at 12 pm, and 5.79±1.20 foton/msn at 4 pm. No statistical difference was found between the measurements (p=0.08. Subgroup analysis according to eye color, revealed no significant difference between flare measurements in brown, hazel, and green eyes (p=0.21. Correlation analysis demonstrated association between age and all flare measurements within the day (r=0.24, p=0.03; r=0.41, p=0.01, r=0.27, p=0.01. Conclusion: No significant diurnal change was detected in the flare measurements of our study subjects but positive correlation with age was observed. Hence, all flare measurements within a day are reliable and have high repeatability in healthy subjects. (Turk J Ophthalmol 2015; 45: 52-5

  16. Diurnal variations of summer precipitation in Beijing

    Institute of Scientific and Technical Information of China (English)

    LI Jian; YU RuCong; WANG JianJie

    2008-01-01

    Climatic characteristics and secular trends of diurnal variations of summer precipitation in Beijing are studied using hourly self-recording rain-gauge data during 1961-2004. The results show that both rainfall amount and rainfall frequency present high values from late afternoon to early morning and reach the minima around noon. Two separate peaks can be identified in the high value period, one in the late afternoon and the other in the early morning. Taking the rainfall duration into account, it is found that the rainfall during late afternoon to midnight mainly comes from the short-duration rainfall events (an event of 1-6 hours in duration), while the rainfall during midnight to early morning is ac-cumulated mostly by the long-duration rainfall events (an event that lasts longer than 6 hours). In the recent 40 years, the summer precipitation in Beijing has been considerably restructured. The total rainfall amount of short-duration events has increased significantly, while the total rainfall amount of long-duration events has decreased.

  17. An empirical model simulating long-term diurnal CO2 flux for diverse vegetation types

    Directory of Open Access Journals (Sweden)

    A. D. Richardson

    2008-10-01

    Full Text Available We present an empirical model for the estimation of diurnal variability in net ecosystem CO2 exchange (NEE. The model is based on the use of a nonrectangular hyperbola for photosynthetic response of canopy and was constructed by using a dataset obtained from the AmeriFlux network and containing continuous eddy covariance CO2 flux from 26 ecosystems over seven biomes. The model uses simplified empirical expression of seasonal variability in biome-specific physiological parameters with air temperature, vapor pressure deficit, and precipitation. The physiological parameters of maximum CO2 uptake rate by the canopy and ecosystem respiration had biome-specific responses to environmental variables. The estimated physiological parameters had reasonable magnitudes and seasonal variation and gave reasonable timing of the beginning and end of the growing season over various biomes, but they were less satisfactory for disturbed grassland and savanna than for forests. Comparison with observational data revealed that the diurnal cycle of NEE was generally well predicted all year round by the model. The model gave satisfactory results even for tundra, which had very small amplitudes of NEE variability. These results suggest that this model with biome-specific parameters will be applicable to numerous terrestrial biomes, particularly forest ones.

  18. Photometric stability analysis of the Exoplanet Characterisation Observatory

    CERN Document Server

    Waldmann, I P; Swinyard, B; Tinetti, G; Amaral-Rogers, A; Spencer, L; Tessenyi, M; Ollivier, M; Foresto, V Coudé du

    2013-01-01

    Photometric stability is a key requirement for time-resolved spectroscopic observations of transiting extrasolar planets. In the context of the Exoplanet Characterisation Observatory (EChO) mission design, we here present and investigate means of translating spacecraft pointing instabilities as well as temperature fluctuation of its optical chain into an overall error budget of the exoplanetary spectrum to be retrieved. Given the instrument specifications as of date, we investigate the magnitudes of these photometric instabilities in the context of simulated observations of the exoplanet HD189733b secondary eclipse.

  19. Steps Toward a Common Near-Infrared Photometric System

    CERN Document Server

    Tokunaga, A T

    2007-01-01

    The proliferation of near-infrared (1--5 $\\mu$m) photometric systems over the last 30 years has made the comparison of photometric results difficult. In an effort to standardize infrared filters in use, the Mauna Kea Observatories near-infrared filter set has been promoted among instrument groups through combined filter production runs. The characteristics of this filter set are summarized, and some aspects of the filter wavelength definitions, the flux density for zero magnitude, atmospheric extinction coefficients, and color correction to above the atmosphere are discussed.

  20. Comparision of approaches to photometric redshift estimation of quasars

    Science.gov (United States)

    Tu, Yang; Zhang, Yanxia; Zhao, Yongheng; Tian, Haijun

    2015-08-01

    Based on databases from various different band photometric surveys (optical from SDSS, infrared from UKIDSS and WISE), we compare k-nearest neighbor regression based on KD-tree and Ball-tree, LASSO, PLS (Partial Least Squares), SDG, ridge regression and kernel ridge regression applied for photometric redshift estimation of quasars. The experimental result shows that the perfomance order of these methods is KD-tree kNN, Ball-tree kNN, kernal ridge regression, ridge regression, PLS, SGD, LASSO.

  1. V409 Tau As Another AA Tau: Photometric Observations of Stellar Occultations by the Circumstellar Disk

    CERN Document Server

    Rodriguez, Joseph E; Stassun, Keivan G; Siverd, Robert J; Cargile, Phillip; Weintraub, David A; Beatty, Thomas G; Gaudi, B Scott; Mamajek, Eric E; Sanchez, Nicole

    2015-01-01

    AA Tau is a well studied young stellar object that presents many of the photometric characteristics of a Classical T Tauri star (CTTS), including short-timescale stochastic variability attributed to spots and/or accretion as well as long duration dimming events attributed to occultations by vertical features (e.g., warps) in its circumstellar disk. We present new photometric observations of AA Tau from the Kilodegree Extremely Little Telescope North (KELT-North) which reveal a deep, extended dimming event in 2011, which we show supports the interpretation by Bouvier et al. (2013) of an occultation by a high-density feature in the circumstellar disk located >8 AU from the star. We also present KELT-North observations of V409 Tau, a relatively unstudied young stellar object also in Taurus-Auriga, showing short timescale erratic variability, along with two separate long and deep dimming events, one from January 2009 through late October 2010, and the other from March 2012 until at least September 2013. We interp...

  2. New Photometric Study of the Interacting Binary Star System Y Piscium

    Science.gov (United States)

    Reed, Phillip A.; Yuhas, Bernard J.

    2012-11-01

    We present a new photometric study of Y Piscium (Y Psc), which includes BVI light curves and a period analysis. With an orbital period of 3.77 days, this neglected system undergoes period changes described by an overall quadratic ephemeris with oscillating variability superimposed. Variations in the light curve and ephemeris curve, possibly resulting from changes in the accretion structure and mass transfer rate, suggest that Y Psc may be a direct-impact system like U Coronae Borealis and U Sagittae, which are known to exhibit variable accretion states. The 0.46 m modified Cassegrain telescope at the Kutztown University Observatory (Kutztown, PA) was used to obtain the new CCD photometry over 18 nights of observation between 2011 October 5 and 2012 January 15. We present a new photometric model that was determined using the computer program PHOEBE and suggest a reclassification of the spectral type of the primary star. An analysis of previously recorded times of minimum, in conjunction with our observations, was used to suggest possible physical mechanisms intrinsic to the system. These include magnetic activity (Applegate mechanism) and angular momentum transfer, while the possibility of a third body is ruled out. The results presented here demonstrate that Y Psc is an excellent candidate for a high-resolution spectroscopic study.

  3. Galaxy clustering, photometric redshifts and diagnosis of systematics in the DES Science Verification data

    CERN Document Server

    Crocce, M; Bauer, A H; Ross, A J; Sevilla-Noarbe, I; Giannantonio, T; Sobreira, F; Sanchez, J; Gaztanaga, E; Kind, M Carrasco; Sanchez, C; Bonnett, C; Benoit-Levy, A; Brunner, R J; Rosell, A Carnero; Cawthon, R; Fosalba, P; Hartley, W; Kim, E J; Leistedt, B; Miquel, R; Percival, W J; Rosenfeld, R; Rykoff, E S; Sanchez, E; Abbott, T; Abdalla, F B; Allam, S; Banerji, M; Bernstein, G M; Bertin, E; Brooks, D; Buckley-Geer, E; Burke, D L; Capozzi, D; Castander, F J; Cunha, C E; D'Andrea, C B; da Costa, L N; Desai, S; Diehl, H T; Eifler, T F; Evrard, A E; Neto, A Fausti; Fernandez, E; Finley, D A; Flaugher, B; Frieman, J; Gerdes, D W; Gruen, D; Gruendl, R A; Gutierrez, G; Honscheid, K; James, D J; Kuehn, K; Kuropatkin, N; Lahav, O; Li, T S; Lima, M; Maia, M A G; March, M; Marshall, J L; Martini, P; Melchior, P; Miller, C J; Neilsen, E; Nichol, R C; Nord, B; Ogando, R; Plazas, A A; Romer, A K; Sako, M; Santiago, B; Schubnell, M; Smith, R C; Soares-Santos, M; Suchyta, E; Swanson, M E C; Tarle, G; Thaler, J; Thomas, D; Vikram, V; Walker, A R; Wechsler, R H; Weller, J; Zuntz, J

    2015-01-01

    We study the clustering of galaxies detected at $i<22.5$ in the Science Verification observations of the Dark Energy Survey (DES). Two-point correlation functions are measured using $2.3\\times 10^6$ galaxies over a contiguous 116 deg$^2$ region in five bins of photometric redshift width $\\Delta z = 0.2$ in the range $0.2 < z < 1.2.$ The impact of photometric redshift errors are assessed by comparing results using a template-based photo-$z$ algorithm (BPZ) to a machine-learning algorithm (TPZ). A companion paper (Leistedt et al 2015) presents maps of several observational variables (e.g. seeing, sky brightness) which could modulate the galaxy density. Here we characterize and mitigate systematic errors on the measured clustering which arise from these observational variables, in addition to others such as Galactic dust and stellar contamination. After correcting for systematic effects we measure galaxy bias over a broad range of linear scales relative to mass clustering predicted from the Planck $\\Lam...

  4. Nonlinear interaction between the diurnal and semidiurnal tides: Terdiurnal and diurnal secondary waves

    Science.gov (United States)

    Teitelbaum, H.; Vial, F.; Manson, A. H.; Giraldez, R.; Masseboeuf, M.

    1989-01-01

    Many years of measurements obtained using French meteor radars at Garchy (latitude 47 N) and Montpazier (latitude 44 N) are used to show the existence of an 8 hour oscillation. Some examples of the structure of this wave are displayed and compared with measurements performed at Saskatoon (latitude 52 N) and Budrio (latitude 45 N). This wave can be interpreted as the solar driven terdiurnal tide, or as the result of the nonlinear interaction between the diurnal and semidiurnal tides. Both hypotheses are tested with numerical models. Incidentally, the possible existence of a 24 hour wave resulting from this interaction is also studied.

  5. Topography induced spatial variations in diurnal cycles of assimilation and latent heat of Mediterranean forest

    Directory of Open Access Journals (Sweden)

    C. van der Tol

    2007-01-01

    Full Text Available The aim of this study is to explain topography induced spatial variations in the diurnal cycles of assimilation and latent heat of Mediterranean forest. Spatial variations of the fluxes are caused by variations in weather conditions and in vegetation characteristics. Weather conditions reflect short-term effects of climate, whereas vegetation characteristics, through adaptation and acclimation, long-term effects of climate. In this study measurements of plant physiology and weather conditions are used to explain observed differences in the fluxes. A model is used to study which part of the differences in the fluxes is caused by weather conditions and which part by vegetation characteristics. Data were collected at four experimental sub-Mediterranean deciduous forest plots in a heterogeneous terrain with contrasting aspect, soil water availability, humidity and temperature. We used a sun-shade model to scale fluxes from leaf to canopy, and calculated the canopy energy balance. Parameter values were derived from measurements of light interception, leaf chamber photosynthesis, leaf nitrogen content and 13C isotope discrimination in leaf material. Leaf nitrogen content is a measure of photosynthetic capacity, and 13C isotope discrimination of water use efficiency. For validation, sap-flux based measurements of transpiration were used. The model predicted diurnal cycles of transpiration and stomatal conductance, both their magnitudes and differences in afternoon stomatal closure between slopes of different aspect within the confidence interval of the validation data. Weather conditions mainly responsible for the shape of the diurnal cycles, and vegetation parameters for the magnitude of the fluxes. Although the data do not allow for a quantification of the two effects, the differences in vegetation parameters and weather among the plots and the sensitivity of the fluxes to them suggest that the diurnal cycles were more strongly affected by spatial

  6. Parents Function and Behavioral Disorders in Children with and without Diurnal Voiding Dysfunction: A Comparative Study

    Directory of Open Access Journals (Sweden)

    Parsa Yousefi

    2014-09-01

    Full Text Available Background: Diurnal voiding dysfunction is one of the most common causes of pediatric urology clinic admissions. It can cause behavioral problems for children and their parents. We lunch this study to compare the parents’ function and children’s behavior problem in pediatric patients suffering from diurnal voiding dysfunction referring Arak Amir Kabir hospital. Materials and Methods: To perform this case-control study, we recruit 116 children with diurnal voiding dysfunction and compared them with other 116 children non-affected children aged between 5 to 16 years old. The child behavior checklist (CBCL4/18 for children behavior assessment and Global Assessment of Functioning (GAF for the evaluation of their parent’s behavior was completed by the parents. Data was analyzed using ANOVA, qualitative variables and χ2 formula. Results: Among 116 patient with voiding dysfunction, 10 case (8.6% showed behavioral problem while this figure was 3 case (2.6% in the control group, denoting a significant difference (p=0.04. Moreover 20 children (17.2% in the case group and 9 children (7.8% in the control group had internalizing problem (p=0.02. Twenty two children (19% with voiding dysfunction and 8 children (6.9% in the healthy group had externalizing problem which was also a significant difference (p=0.01. As a significant difference (0.01, the parent’s average stress and behavior scores in case and control group were 3.65 and 3.76, respectively. Conclusion: The higher prevalence of behavioral problem in the children suffering from diurnal voiding dysfunction and their parent’s functional impairment highlights the importance of early parent’s intervention for early treatment and subsequently prevention of future behavioral problem in their sibling.

  7. Diurnal variation of tropospheric temperature at a tropical station

    Directory of Open Access Journals (Sweden)

    K. Revathy

    Full Text Available The vertical velocity in the troposphere-lower stratosphere region measured using MST radar has been utilized to evaluate the temperature profile in the region. The diurnal variation of the tropospheric temperature on one day in August 1998 at the tropical station Gadanki (13.5° N, 79.2° E has been studied using the MST radar technique. The diurnal variation of the temperature revealed a prominent diurnal variation with the peak in the afternoon hours increasingly delayed in altitude. The tropopause temperature and altitude exhibited a clear diurnal cycle.

    Key words. Atmospheric composition and structure (pressure, density and temperature; troposphere - composition and chemistry; instruments and technique

  8. Diurnal course of photosynthesis in Myriophyllum spicatum and Oedogonium

    Energy Technology Data Exchange (ETDEWEB)

    McCracken, M.D. (Texas Christian Univ., Ft. Worth); Adams, M.S.; Titus, J.; Stone, W.

    1975-01-01

    Diurnal patterns of photosynthesis were determined for Myriophyllum and Oedogonium in Lake Wingra, Wisconsin, on four dates in 1971 and two in 1972. Photosynthesis was measured by the carbon-14 technique. Mid-day photosynthetic depression was observed on some dates, but not on others. Photosynthesis was also studied under controlled laboratory conditions. The possible influence of internal rhythms, light, and nutrients on diurnal photosynthesis patterns is discussed.

  9. Central melanopsin projections in the diurnal rodent, Arvicanthis niloticus

    DEFF Research Database (Denmark)

    Langel, Jennifer L; Smale, Laura; Esquiva, Gema;

    2015-01-01

    The direct effects of photic stimuli on behavior are very different in diurnal and nocturnal species, as light stimulates an increase in activity in the former and a decrease in the latter. Studies of nocturnal mice have implicated a select population of retinal ganglion cells that are intrinsica...... in nocturnal rodents. Overall, these data suggest that although ipRGCs and their projections are very similar in diurnal and nocturnal rodents, they may not be identical....

  10. The Nainital–Cape Survey: A Search for Variability in Ap and Am Stars

    Indian Academy of Sciences (India)

    Santosh Joshi

    2005-06-01

    The ``Nainital–Cape Survey” program for searching photometric variability in chemically peculiar (CP) stars was initiated in 1997 at ARIES, Nainital. We present here the results obtained to date. The Am stars HD 98851, HD 102480, HD 13079 and HD 113878 were discovered to exhibit Scuti type variability. Photometric variability was also discovered in HD 13038, for which the type of peculiarity and variability is not fully explained. The null results of this survey are also presented and discussed.

  11. Atmospheric diurnal variations observed with GPS radio occultation soundings

    Directory of Open Access Journals (Sweden)

    F. Xie

    2010-07-01

    Full Text Available The diurnal variation, driven by solar forcing, is a fundamental mode in the Earth's weather and climate system. Radio occultation (RO measurements from the six COSMIC satellites (Constellation Observing System for Meteorology, Ionosphere and Climate provide nearly uniform global coverage with high vertical resolution, all-weather and diurnal sampling capability. This paper analyzes the diurnal variations of temperature and refractivity from three-year (2007–2009 COSMIC RO measurements in the troposphere and stratosphere between 30° S and 30° N. The RO observations reveal both propagating and trapped vertical structures of diurnal variations, including transition regions near the tropopause where data with high vertical resolution are critical. In the tropics the diurnal amplitude in refractivity shows the minimum around 14 km and increases to a local maximum around 32 km in the stratosphere. The upward propagating component of the migrating diurnal tides in the tropics is clearly captured by the GPS RO measurements, which show a downward progression in phase from stratopause to the upper troposphere with a vertical wavelength of about 25 km. At ~32 km the seasonal variation of the tidal amplitude maximizes at the opposite side of the equator relative to the solar forcing. The vertical structure of tidal amplitude shows strong seasonal variations and becomes asymmetric along the equator and tilted toward the summer hemisphere in the solstice months. Such asymmetry becomes less prominent in equinox months.

  12. Diurnal Variation of Precipitation During MC3E Campaign

    Science.gov (United States)

    Tao, Wei-Kuo; Wu, Di; Matsui, Toshi; Peters-Lidard, Christa; Hou, Arthur; Rienecker, Michele

    2012-01-01

    The diurnal variation of precipitation processes in the United States (US) is well recognized but incompletely understood (Cabone et al. 2002). The diurnal cycle of precipitation has been studied using surface rainfall data, radar reflectivity data, and satellite-derived cloudiness and precipitation (Wallace 1975; Dai et al. 1999; Carbone et al. 2002; Carbone and Tuttle, 2008; Parker and Ahijevych, 2007; Matsui et al. 2010 and others). These observations indicate that the summer-time precipitation most of the North America and typically feature late-afternoon precipitation maxima. These diurnal variation of precipitation can also be generally categorized into three different types: 1) afternoon rainfall maxima due to mesoscale and local circulations over the south and east of the Mississippi and Ohio valleys, 2) nocturnal rainfall maxima from eastward-propagating mesoscale convective systems (MCSs) over the Lee side of Rocky Mountain regions and 3) afternoon rainfall maxima in the Appalachian Mountains, and then propagate eastward toward the coast. The main objective of this paper is to use a regional cloud-scale model with very high-resolution (i.e., WRF) to examine the WRF ability to simulate diurnal variation of precipitation. Specifically, the study will (1) identify the physical processes responsible to diurnal variation of precipitation, (2) examine the sensitivity of resolution (2, 6, 18, and 30 km) to model simulated diurnal variation of precipitation and (3) identify the relationships between microphysics and cumulus parameterization schemes.

  13. OMC/INTEGRAL photometric observations of pulsating components in eclipsing binaries and characterization of DY Aqr

    Science.gov (United States)

    Alfonso-Garzón, J.; Montesinos, B.; Moya, A.; Mas-Hesse, J. M.; Martín-Ruiz, S.

    2014-10-01

    We present the search for eclipsing binaries with a pulsating component in the first catalogue of optically variable sources observed by Optical Monitoring Camera (OMC)/INTEGRAL, which contains photometric data for more than 1000 eclipsing binaries. Five objects were found and a detailed analysis of one of them, DY Aqr, has been performed. Photometric and spectroscopic observations of DY Aqr were obtained to analyse the binary system and the pulsational characteristics of the primary component. By applying the binary modelling software PHOEBE to the OMC and ground-based photometric light curves, and to the radial velocity curve obtained using echelle high-resolution spectroscopy, the physical parameters of the system have been determined. Frequency analysis of the residual data has been performed using Fourier techniques to identify pulsational frequencies. We have built a grid of theoretical models to classify spectroscopically the primary component as an A7.5V star (plus or minus one spectral subtype). The best orbital fit was obtained for a semidetached system configuration. According to the binary modelling, the primary component has Teff = 7625 ± 125 K and log g = 4.1 ± 0.1 and the secondary component has Teff = 3800 ± 200 K and log g = 3.3 ± 0.1, although it is too faint to isolate its spectral features. From the analysis of the residuals, we have found a main pulsation frequency at 23.37 d-1, which is typical of a δ Scuti star. In the O-C diagram, no evidence of orbital period changes over the last 8 yr has been found.

  14. Clues to the nature of SN 2009ip from photometric and spectroscopic evolution to late times

    Energy Technology Data Exchange (ETDEWEB)

    Graham, M. L. [Astronomy Department, University of California, Berkeley, CA 94720 (United States); Sand, D. J. [Physics Department, Texas Tech University, Lubbock, TX 79409 (United States); Valenti, S.; Howell, D. A.; Parrent, J. [Las Cumbres Observatory Global Telescope Network, Goleta, CA 93117 (United States); Halford, M.; Zaritsky, D. [Astronomy Department, University of Arizona, Tucson, AZ 85721 (United States); Bianco, F. [Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Rest, A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Dilday, B., E-mail: melissagraham@berkeley.edu [North Idaho College, 1000 W. Garden Avenue, Coeur d' Alene, ID 83814 (United States)

    2014-06-01

    We present time series photometric and spectroscopic data for the transient SN 2009ip from the start of its outburst in 2012 September until 2013 November. These data were collected primarily with the new robotic capabilities of the Las Cumbres Observatory Global Telescope Network, a specialized facility for time domain astrophysics, and includes supporting high-resolution spectroscopy from the Southern Astrophysical Research Telescope, Kitt Peak National Observatory, and Gemini Observatory. Based on our nightly photometric monitoring, we interpret the strength and timing of fluctuations in the light curve as interactions between fast-moving ejecta and an inhomogeneous circumstellar material (CSM) produced by past eruptions of this massive luminous blue variable (LBV) star. Our time series of spectroscopy in 2012 reveals that, as the continuum and narrow Hα flux from CSM interactions declines, the broad component of Hα persists with supernova (SN)-like velocities that are not typically seen in LBVs or SN impostor events. At late times, we find that SN 2009ip continues to decline slowly, at ≲ 0.01 mag day{sup –1}, with small fluctuations in slope similar to Type IIn supernovae (SNe IIn) or SN impostors but no further LBV-like activity. The late-time spectrum features broad calcium lines similar to both late-time SNe and SN impostors. In general, we find that the photometric and spectroscopic evolution of SN 2009ip is more similar to SNe IIn than either continued eruptions of an LBV star or SN impostors but we cannot rule out a nonterminal explosion. In this context, we discuss the implications for episodic mass loss during the late stages of massive star evolution.

  15. A photometric study of chemically peculiar stars with the STEREO satellites. I. Magnetic chemically peculiar stars

    CERN Document Server

    Wraight, K T; Netopil, M; Paunzen, E; Rode-Paunzen, M; Bewsher, D; Norton, A J; White, G J

    2011-01-01

    About 10% of upper main sequence stars are characterised by the presence of chemical peculiarities, often found together with a structured magnetic field. The atmospheres of most of those chemically peculiar stars present surface spots, leading to photometric variability caused by rotational modulation. The study of the light curves of those stars therefore, permits a precise measurement of their rotational period, which is important to study stellar evolution and to plan further detailed observations. We analysed the light curves of 1028 chemically peculiar stars obtained with the STEREO spacecraft. We present here the results obtained for the 337 magnetic chemically peculiar stars in our sample. Thanks to the cadence and stability of the photometry, STEREO data are perfectly suitable to study variability signals with a periodicity typical of magnetic chemically peculiar stars. Using a matched filter algorithm and then two different period searching algorithms, we compiled a list of 82 magnetic chemically pe...

  16. Photometric Redshift and Classification for the XMM-COSMOS Sources

    NARCIS (Netherlands)

    Salvato, M.; Hasinger, G.; Ilbert, O.; Zamorani, G.; Brusa, M.; Scoville, N. Z.; Rau, A.; Capak, P.; Arnouts, S.; Aussel, H.; Bolzonella, M.; Buongiorno, A.; Cappelluti, N.; Caputi, K.; Civano, F.; Cook, R.; Elvis, M.; Gilli, R.; Jahnke, K.; Kartaltepe, J. S.; Impey, C. D.; Lamareille, F.; Le Floch, E.; Lilly, S.; Mainieri, V.; McCarthy, P.; McCracken, H.; Mignoli, M.; Mobasher, B.; Murayama, T.; Sasaki, S.; Sanders, D. B.; Schiminovich, D.; Shioya, Y.; Shopbell, P.; Silverman, J.; Smolcic, V.; Surace, J.; Taniguchi, Y.; Thompson, D.; Trump, J. R.; Urry, M.; Zamojski, M.

    2009-01-01

    We present photometric redshifts and spectral energy distribution (SED) classifications for a sample of 1542 optically identified sources detected with XMM in the COSMOS field. Our template fitting classifies 46 sources as stars and 464 as nonactive galaxies, while the remaining 1032 require templat

  17. Photometric Redshift and Classification for the XMM-COSMOS Sources

    NARCIS (Netherlands)

    Salvato, M.; Hasinger, G.; Ilbert, O.; Zamorani, G.; Brusa, M.; Scoville, N. Z.; Rau, A.; Capak, P.; Arnouts, S.; Aussel, H.; Bolzonella, M.; Buongiorno, A.; Cappelluti, N.; Caputi, K.; Civano, F.; Cook, R.; Elvis, M.; Gilli, R.; Jahnke, K.; Kartaltepe, J. S.; Impey, C. D.; Lamareille, F.; Le Floch, E.; Lilly, S.; Mainieri, V.; McCarthy, P.; McCracken, H.; Mignoli, M.; Mobasher, B.; Murayama, T.; Sasaki, S.; Sanders, D. B.; Schiminovich, D.; Shioya, Y.; Shopbell, P.; Silverman, J.; Smolcic, V.; Surace, J.; Taniguchi, Y.; Thompson, D.; Trump, J. R.; Urry, M.; Zamojski, M.

    2009-01-01

    We present photometric redshifts and spectral energy distribution (SED) classifications for a sample of 1542 optically identified sources detected with XMM in the COSMOS field. Our template fitting classifies 46 sources as stars and 464 as nonactive galaxies, while the remaining 1032 require

  18. PHOTOMETRIC EVIDENCE FOR THE OSMOTIC BEHAVIOR OF RAT LIVER MICROSOMES

    Science.gov (United States)

    Tedeschi, Henry; James, Joseph M.; Anthony, William

    1963-01-01

    Electron microscope observations are consistent with the interpretation that the elements of the endoplasmic reticulum are osmotically active in situ as well as after isolation. More recently, it has been reported that microsomal suspensions equilibrate almost completely with added C14-sucrose and that no osmotic behavior is evident from photometric data. These findings were considered at variance with the electron microscope data. However, equilibration with added label simply attests to a relatively high permeability, and, in addition, the photometric data need not be critical. Osmotic volume changes, measured photometrically, may be masked by concomitant events (e.g., changes in the refractive index of the test solutions at varying osmotic pressures, breakdown of the particles, and agglutination). For these reasons the photometric experiments were repeated. In this work, the reciprocal of optical density of microsomal suspensions was found to vary linearly with the reciprocal of concentration of the medium at constant refractive index. These changes probably correspond to osmotic volume changes, since the effect was found to be (a) independent of substance used and (b) osmotically reversible. The transmission of the suspension was found to vary with the refractive index of the medium, the concentration of particles, and the wavelength of incident light, according to relationships that are similar to or identical with those obtained for mitochondrial suspensions. PMID:14064105

  19. Solving the uncalibrated photometric stereo problem using total variation

    DEFF Research Database (Denmark)

    Quéau, Yvain; Lauze, Francois Bernard; Durou, Jean-Denis

    2013-01-01

    In this paper we propose a new method to solve the problem of uncalibrated photometric stereo, making very weak assumptions on the properties of the scene to be reconstructed. Our goal is to solve the generalized bas-relief ambiguity (GBR) by performing a total variation regularization of both th...

  20. Photometric redshifts of galaxies from SDSS and 2MASS

    Institute of Scientific and Technical Information of China (English)

    Tao Wang; Jia-Sheng Huang; Qiu-Sheng Gu

    2009-01-01

    In order to find the physical parameters which determine the accuracy of pho- tometric redshifts, we compare the spectroscopic and photometric redshifts (photo-z's) for a large sample of ~ 80 000 SDSS-2MASS galaxies. Photo-z's in this paper are es- timated by using the artificial neural network photometric redshift method (ANNz). For a subset of~40000 randomly selected galaxies, we find that the photometric redshift recovers the spectroscopic redshifi distribution very well with rms of 0.016. Our main results are as follows: (1) Using magnitudes directly as input parameters produces more accurate photo-z's than using colors; (2) The inclusion of 2MASS (3, H, Ks) bands does not improve photo-z's significantly, which indicates that near infrared data might not be important for the low-redshift sample; (3) Adding the concentration index (essentially the steepness of the galaxy brightness profile) as an extra input can improve the photo-z's estimation up to~10 percent; (4) Dividing the sample into early- and late-type galaxies by using the concentration index, normal and abnormal galaxies by using the emission line flux ratios, and red and blue galaxies by using color index (g - r), we can improve the accuracy of photo-z's significantly; (5) Our analysis shows that the outliers (where there is a big difference between the spectroscopic and photometric redshifts) are mainly correlated with galaxy types, e.g., most outliers are late-type (blue) galaxies.

  1. Comparison of Approaches to Photometric Redshift Estimation of Quasars

    Science.gov (United States)

    Tu, Yang; Zhang, Yan-Xia; Zhao, Yong-Heng; Tian, Hai-Jun

    We probe many kinds of approaches used for photometric redshift estimation of quasars, including KNN (K-nearest neighbor algorithm), Lasso (Least Absolute Shrinkage and Selection Operator), PLS (Partial Least Square regression), ridge regression, SGD (Stochastic Gradient Descent) and Extra-Trees.

  2. The Angular Power Spectra of Photometric SDSS LRGs

    CERN Document Server

    Thomas, Shaun A; Lahav, Ofer

    2010-01-01

    We construct new galaxy angular power spectra based on the extended, updated and final SDSS II Luminous Red Galaxy (LRG) photometric redshift survey: MegaZ DR7. Encapsulating 7746 deg^{2} we utilise 723,556 photometrically determined LRGs between 0.45 < z < 0.65 in a 3.3 (Gpc h^{-1})^3 spherical harmonic analysis of the galaxy distribution. By combining four photometric redshift bins we find preliminary parameter constraints of f_{b} = \\Omega_{b}/\\Omega_{m} = 0.173 +/- 0.046 and \\Omega_{m} = 0.260 +/- 0.035 assuming H_{0} = 75 km s^{-1} Mpc^{-1}, n_{s}=1 and \\Omega_{k} = 0. These limits are consistent with the CMB and the previous data release (DR4). The C_{\\ell} are sensitive to redshift space distortions and therefore we also recast our constraints into a measurement of \\beta ~ \\Omega_{m}^{0.55}/b in different redshift shells. The robustness of these power spectra with respect to a number of potential systematics such as extinction, photometric redshift and ANNz training set extrapolation are examined...

  3. Correlates of diurnal sleep patterns in infants of adolescent and adult single mothers.

    Science.gov (United States)

    Becker, P T; Chang, A; Kameshima, S; Bloch, M

    1991-04-01

    Sleep behavior has been related to both child and environmental factors, but the relative importance of these factors is not yet clear. This study was an examination of the relation of diurnal sleep patterns to perinatal risk, infant temperament, home environment, parenting stress, emotional support, and social class. Twenty-three adolescent and 23 single adult mothers and infants were assessed in the home at 4 and 12 months. Percent sleep during the night was most strongly related to parenting stress and variability of night sleep to emotional support. Emotional support mediated effects of stress at 4 months. Results support the value of clinical assessment of sleep behavior.

  4. New CCD Photometric Study of AM Cnc

    CERN Document Server

    Tasselli, D

    2015-01-01

    We present in this paper the new study of variable star AM Cnc, a short period RRab star, in orther to determine, through the light curve and the physical parameters. The Star were observed for a total of 293 sessions shooting, and exhibits light curve modulation, the so called Blazhko effect with the shortest modulation Period=0d.559233 ever observed. We observed this star with the 0,6 mt telescope of the Astronomical Observatory of Andrate (OAA) - To and the result detect small but definite modification in temperature and mean radius of the star itself. All results are compared with previously published literature values and discussed.

  5. Evaluating the performance of ENVI-met model in diurnal cycles for different meteorological conditions

    Science.gov (United States)

    Acero, Juan A.; Arrizabalaga, Jon

    2016-11-01

    Urban areas are known to modify meteorological variables producing important differences in small spatial scales (i.e. microscale). These affect human thermal comfort conditions and the dispersion of pollutants, especially those emitted inside the urban area, which finally influence quality of life and the use of public open spaces. In this study, the diurnal evolution of meteorological variables measured in four urban spaces is compared with the results provided by ENVI-met (v 4.0). Measurements were carried out during 3 days with different meteorological conditions in Bilbao in the north of the Iberian Peninsula. The evaluation of the model accuracy (i.e. the degree to which modelled values approach measured values) was carried out with several quantitative difference metrics. The results for air temperature and humidity show a good agreement of measured and modelled values independently of the regional meteorological conditions. However, in the case of mean radiant temperature and wind speed, relevant differences are encountered highlighting the limitation of the model to estimate these meteorological variables precisely during diurnal cycles, in the considered evaluation conditions (sites and weather).

  6. Exploring the SDSS photometric galaxies with clustering redshifts

    Science.gov (United States)

    Rahman, Mubdi; Mendez, Alexander J.; Ménard, Brice; Scranton, Ryan; Schmidt, Samuel J.; Morrison, Christopher B.; Budavári, Tamás

    2016-07-01

    We apply clustering-based redshift inference to all extended sources from the Sloan Digital Sky Survey photometric catalogue, down to magnitude r = 22. We map the relationships between colours and redshift, without assumption of the sources' spectral energy distributions (SEDs). We identify and locate star-forming quiescent galaxies, and active galactic nuclei, as well as colour changes due to spectral features, such as the 4000 Å break, redshifting through specific filters. Our mapping is globally in good agreement with colour-redshift tracks computed with SED templates, but reveals informative differences, such as the need for a lower fraction of M-type stars in certain templates. We compare our clustering-redshift estimates to photometric redshifts and find these two independent estimators to be in good agreement at each limiting magnitude considered. Finally, we present the global clustering-redshift distribution of all Sloan extended sources, showing objects up to z ˜ 0.8. While the overall shape agrees with that inferred from photometric redshifts, the clustering-redshift technique results in a smoother distribution, with no indication of structure in redshift space suggested by the photometric-redshift estimates (likely artefacts imprinted by their spectroscopic training set). We also infer a higher fraction of high-redshift objects. The mapping between the four observed colours and redshift can be used to estimate the redshift probability distribution function of individual galaxies. This work is an initial step towards producing a general mapping between redshift and all available observables in the photometric space, including brightness, size, concentration, and ellipticity.

  7. Zooplankton spatial and diurnal variations in the Changjiang River estuary before operation of the Three Gorges Dam

    Institute of Scientific and Technical Information of China (English)

    GAO Xuelu; SONG Jinming; LI Xuegang

    2011-01-01

    Estuarine plankton communities can serve as indicators of ecosystem modification in response to anthropogenic influences. The main objectives of this study were to describe the spatial distribution and diurnal variability in zooplankton abundance and biomass over almost entire salinity gradient of the Changjiang (Yangtze) River estuary and to provide a background reference for future studies. To accomplish this, data were collected from 29 stations in the estuary from May 19 to 26, 2003,including two anchor stations. The spatial and diurnal variations in zooplankton characteristics, i.e.abundance, biomass, and gross taxonomic composition, were examined. Generally, both the abundance and biomass gradually increased seaward and presented distinct spatial variations. In addition, the spatial data revealed a significant correlation between abundance and biomass; however, there was no significant correlation between abundance and biomass for the diurnal data. Although the zooplankton composition indicated distinct spatial differences in terms of dominant groups, copepods accounted for >50% of the total zooplankton abundance in most regions and times. Three zooplankton assemblages were recognized through hierarchical cluster analysis. These assemblages existed along the salinity gradient from fresh water to seawater, and their positions coincided with those of the three principal water masses in the estuary. The assemblages were classified as: (1) true estuarine, (2) estuarine and marine, and (3) euryhaline marine, which were characterized by the copepods Sinocalanus dorrii, Labidocera euchaeta, and Calanus sinicus, respectively. Both spatial and diurnal data indicated that there was no significant correlation between zooplankton abundance/biomass and depth-integrated phytoplankton abundance.

  8. Astroinformatics of galaxies and quasars: a new general method for photometric redshifts estimation

    CERN Document Server

    Laurino, Omar; Longo, Giuseppe; Riccio, Giuseppe

    2011-01-01

    With the availability of the huge amounts of data produced by current and future large multi-band photometric surveys, photometric redshifts have become a crucial tool for extragalactic astronomy and cosmology. In this paper we present a novel method, called Weak Gated Experts (WGE), which allows to derive photometric redshifts through a combination of data mining techniques. \

  9. 21 CFR 862.2160 - Discrete photometric chemistry analyzer for clinical use.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Discrete photometric chemistry analyzer for... Clinical Laboratory Instruments § 862.2160 Discrete photometric chemistry analyzer for clinical use. (a) Identification. A discrete photometric chemistry analyzer for clinical use is a device intended to...

  10. Optical Monitoring of Quasars; 1, Variability

    CERN Document Server

    García, A; Jablonski, F J; Terlevich, R J

    1999-01-01

    We present an analysis of quasar variability from data collected during a photometric monitoring of 50 objects carried out at CNPq/Laboratorio Nacional de Astrofisica, Brazil, between March 1993 and July 1996. A distinctive feature of this survey is its photometric accuracy, ~ 0.02 V mag, achieved through differential photometry with CCD detectors, what allows the detection of faint levels of variability. We find that the relative variability, delta = sigma / L, observed in the V band is anti-correlated with both luminosity and redshift, although we have no means of discovering the dominant relation, given the strong coupling between luminosity and redshift for the objects in our sample.We introduce a model for the dependence of quasar variability on frequency that is consistent with multi-wavelength observations of the nuclear variability of the Seyfert galaxy NGC 4151. We show that correcting the observed variability for this effect slightly increases the significance of the trends of variability with lumin...

  11. Photometric selection of Type Ia supernovae in the Supernova Legacy Survey

    CERN Document Server

    Bazin, G; Palanque-Delabrouille, N; Rich, J; Aubourg, E; Astier, P; Balland, C; Basa, S; Carlberg, R G; Conley, A; Fouchez, D; Guy, J; Hardin, D; Hook, I M; Howell, D A; Pain, R; Perrett, K; Pritchet, C J; Regnault, N; Sullivan, M; Fourmanoit, N; Gonzalez-Gaitan, S; Lidman, C; Perlmutter, S; Ripoche, P; Walker, E S

    2011-01-01

    We present a sample of 485 photometrically identified Type Ia supernova candidates mined from the first three years of data of the CFHT SuperNova Legacy Survey (SNLS). The images were submitted to a deferred processing independent of the SNLS real-time detection pipeline. Light curves of all transient events were reconstructed in the g_M, r_M, i_M and z_M filters and submitted to automated sequential cuts in order to identify possible supernovae. Pure noise and long-term variable events were rejected by light curve shape criteria. Type Ia supernova identification relied on event characteristics fitted to their light curves assuming the events to be normal SNe Ia. The light curve fitter SALT2 was used for this purpose, assigning host galaxy photometric redshifts to the tested events. The selected sample of 485 candidates is one magnitude deeper than that allowed by the SNLS spectroscopic identification. The contamination by supernovae of other types is estimated to be 4%. Testing Hubble diagram residuals with ...

  12. Asteroseismology of the Beta Cephei star Nu Eridani: photometric observations and pulsational frequency analysis

    CERN Document Server

    Handler, G; Jerzykiewicz, M; Krisciunas, K; Tshenye, T; Rodríguez, E; Costa, V; Zhou, A Y; Medupe, R; Phorah, W M; Garrido, R; Amado, P J; Paparo, M; Zsuffa, D; Ramokgali, L; Crowe, R; Purves, N; Avila, R; Knight, R; Brassfield, E; Kilmartin, P M; Cottrell, P L

    2004-01-01

    We undertook a multisite photometric campaign for the Beta Cephei star Nu Eridani. More than 600 hours of differential photoelectric uvyV photometry were obtained with 11 telescopes during 148 clear nights. The frequency analysis of our measurements shows that the variability of Nu Eri can be decomposed into 23 sinusoidal components, eight of which correspond to independent pulsation frequencies between 5 - 8 c/d. Some of these are arranged in multiplets, which suggests rotational m-mode splitting of nonradial pulsation modes as the cause. If so, the rotation period of the star must be between 30 - 60 d. One of the signals in the light curves of Nu Eri has a very low frequency of 0.432 c/d. It can be a high-order combination frequency or, more likely, an independent pulsation mode. In the latter case Nu Eri would be both a Beta Cephei star and a slowly pulsating B (SPB) star. The photometric amplitudes of the individual pulsation modes of Nu Eri appear to have increased by about 20 per cent over the last 40 y...

  13. Photometric Investigation of the MBM 12 Molecular Cloud Area in ARIES. III. CCD Photometry

    Science.gov (United States)

    Straižys, V.; Zdanavičius, J.; Zdanavičius, K.; Kazlauskas, A.; Černis, K.; Laugalys, V.; Boyle, R. P.; Corbally, C. J.; Philip, A. G. D.

    Magnitudes and color indices of 138 stars down to l V = 15 mag in the seven-color Vilnius photometric system are determined in the area of the Aries molecular cloud MBM 12. Spectral types, color excesses, interstellar extinctions and distances of stars are determined from the photometric data. For some stars classification is verified from spectrograms. The plot of extinction vs. distance exhibits a steep rise of the extinction up to 4 mag at 300 pc which corresponds to the distance of the dust cloud at 375 pc. However, this distance may be overestimated if the heavily reddened stars found in the present study are not inside the cloud, but behind it. Additionally, a small bump of the extinction is present at 100--140 pc which can be related to the extension of the Taurus-Auriga dark cloud complex. Four known T Tauri type stars were measured and classified, and their variability confirmed. Two new T Tauri stars are suspected. More young objects may be present among the stars with peculiar color indices. Some of them can also be unresolved binaries. Some new heavily reddened stars are identified and discussed.

  14. Specific Diurnal EMG Activity Pattern Observed in Occlusal Collapse Patients: Relationship between Diurnal Bruxism and Tooth Loss Progression

    Science.gov (United States)

    Kawakami, Shigehisa; Kumazaki, Yohei; Manda, Yosuke; Oki, Kazuhiro; Minagi, Shogo

    2014-01-01

    Aim The role of parafunctional masticatory muscle activity in tooth loss has not been fully clarified. This study aimed to reveal the characteristic activity of masseter muscles in bite collapse patients while awake and asleep. Materials and Methods Six progressive bite collapse patients (PBC group), six age- and gender-matched control subjects (MC group), and six young control subjects (YC group) were enrolled. Electromyograms (EMG) of the masseter muscles were continuously recorded with an ambulatory EMG recorder while patients were awake and asleep. Diurnal and nocturnal parafunctional EMG activity was classified as phasic, tonic, or mixed using an EMG threshold of 20% maximal voluntary clenching. Results Highly extended diurnal phasic activity was observed only in the PBC group. The three groups had significantly different mean diurnal phasic episodes per hour, with 13.29±7.18 per hour in the PBC group, 0.95±0.97 per hour in the MC group, and 0.87±0.98 per hour in the YC group (p<0.01). ROC curve analysis suggested that the number of diurnal phasic episodes might be used to predict bite collapsing tooth loss. Conclusion Extensive bite loss might be related to diurnal masticatory muscle parafunction but not to parafunction during sleep. Clinical Relevance: Scientific rationale for study Although mandibular parafunction has been implicated in stomatognathic system breakdown, a causal relationship has not been established because scientific modalities to evaluate parafunctional activity have been lacking. Principal findings This study used a newly developed EMG recording system that evaluates masseter muscle activity throughout the day. Our results challenge the stereotypical idea of nocturnal bruxism as a strong destructive force. We found that diurnal phasic masticatory muscle activity was most characteristic in patients with progressive bite collapse. Practical implications The incidence of diurnal phasic contractions could be used for the prognostic

  15. Specific diurnal EMG activity pattern observed in occlusal collapse patients: relationship between diurnal bruxism and tooth loss progression.

    Directory of Open Access Journals (Sweden)

    Shigehisa Kawakami

    Full Text Available AIM: The role of parafunctional masticatory muscle activity in tooth loss has not been fully clarified. This study aimed to reveal the characteristic activity of masseter muscles in bite collapse patients while awake and asleep. MATERIALS AND METHODS: Six progressive bite collapse patients (PBC group, six age- and gender-matched control subjects (MC group, and six young control subjects (YC group were enrolled. Electromyograms (EMG of the masseter muscles were continuously recorded with an ambulatory EMG recorder while patients were awake and asleep. Diurnal and nocturnal parafunctional EMG activity was classified as phasic, tonic, or mixed using an EMG threshold of 20% maximal voluntary clenching. RESULTS: Highly extended diurnal phasic activity was observed only in the PBC group. The three groups had significantly different mean diurnal phasic episodes per hour, with 13.29±7.18 per hour in the PBC group, 0.95±0.97 per hour in the MC group, and 0.87±0.98 per hour in the YC group (p<0.01. ROC curve analysis suggested that the number of diurnal phasic episodes might be used to predict bite collapsing tooth loss. CONCLUSION: Extensive bite loss might be related to diurnal masticatory muscle parafunction but not to parafunction during sleep. CLINICAL RELEVANCE SCIENTIFIC RATIONALE FOR STUDY: Although mandibular parafunction has been implicated in stomatognathic system breakdown, a causal relationship has not been established because scientific modalities to evaluate parafunctional activity have been lacking. PRINCIPAL FINDINGS: This study used a newly developed EMG recording system that evaluates masseter muscle activity throughout the day. Our results challenge the stereotypical idea of nocturnal bruxism as a strong destructive force. We found that diurnal phasic masticatory muscle activity was most characteristic in patients with progressive bite collapse. PRACTICAL IMPLICATIONS: The incidence of diurnal phasic contractions could be used for

  16. Diurnal cortisol after early institutional care—Age matters

    Directory of Open Access Journals (Sweden)

    Jessica E. Flannery

    2017-06-01

    Full Text Available Several studies have shown that young children who have experienced early caregiving adversity (e.g. previously institutionalization (PI exhibit flattened diurnal cortisol slopes; however, less is known about how these patterns might differ between children and adolescents, since the transition between childhood and adolescence is a time of purported plasticity in the hypothalamic-pituitary-adrenal (HPA axis. PI youth experience a massive improvement in caregiving environment once adopted into families; therefore we anticipated that a developmental increase in HPA axis plasticity during adolescence might additionally allow for an enhanced enrichment effect by the adoptive family. In a cross-sectional sample of 197 youths (PI and Comparison; 4–15 years old we observed age-related group differences in diurnal slope. First replicating previous findings, PI children exhibited flattened diurnal slope. This group difference, however, was not observed in adolescents. Moderation analyses showed that pubertal development, increased time with family, and early adoption contributed to the steeper diurnal cortisol slope in PI adolescents. These findings add support to existing theories positing that the transition between middle childhood and adolescence may mark an additional sensitive period for diurnal cortisol patterning, allowing PI youth to benefit from the enriched environment provided by adoptive parents during this period of development.

  17. Does the Neuroprotective Role of Anandamide Display Diurnal Variations?

    Science.gov (United States)

    Martinez-Vargas, Marina; Morales-Gomez, Julio; Gonzalez-Rivera, Ruben; Hernandez-Enriquez, Carla; Perez-Arredondo, Adan; Estrada-Rojo, Francisco; Navarro, Luz

    2013-01-01

    The endocannabinoid system is a component of the neuroprotective mechanisms that an organism displays after traumatic brain injury (TBI). A diurnal variation in several components of this system has been reported. This variation may influence the recovery and survival rate after TBI. We have previously reported that the recovery and survival rate of rats is higher if TBI occurs at 1:00 than at 13:00. This could be explained by a diurnal variation of the endocannabinoid system. Here, we describe the effects of anandamide administration in rats prior to the induction of TBI at two different times of the day: 1:00 and 13:00. We found that anandamide reduced the neurological damage at both times. Nevertheless, its effects on bleeding, survival, food intake, and body weight were dependent on the time of TBI. In addition, we analyzed the diurnal variation of the expression of the cannabinoid receptors CB1R and CB2R in the cerebral cortex of both control rats and rats subjected to TBI. We found that CB1R protein was expressed more during the day, whereas its mRNA level was higher during the night. We did not find a diurnal variation for the CB2R. In addition, we also found that TBI increased CB1R and CB2R in the contralateral hemisphere and disrupted the CB1R diurnal cycle. PMID:24287910

  18. Does the Neuroprotective Role of Anandamide Display Diurnal Variations?

    Directory of Open Access Journals (Sweden)

    Marina Martinez-Vargas

    2013-11-01

    Full Text Available The endocannabinoid system is a component of the neuroprotective mechanisms that an organism displays after traumatic brain injury (TBI. A diurnal variation in several components of this system has been reported. This variation may influence the recovery and survival rate after TBI. We have previously reported that the recovery and survival rate of rats is higher if TBI occurs at 1:00 than at 13:00. This could be explained by a diurnal variation of the endocannabinoid system. Here, we describe the effects of anandamide administration in rats prior to the induction of TBI at two different times of the day: 1:00 and 13:00. We found that anandamide reduced the neurological damage at both times. Nevertheless, its effects on bleeding, survival, food intake, and body weight were dependent on the time of TBI. In addition, we analyzed the diurnal variation of the expression of the cannabinoid receptors CB1R and CB2R in the cerebral cortex of both control rats and rats subjected to TBI. We found that CB1R protein was expressed more during the day, whereas its mRNA level was higher during the night. We did not find a diurnal variation for the CB2R. In addition, we also found that TBI increased CB1R and CB2R in the contralateral hemisphere and disrupted the CB1R diurnal cycle.

  19. Effects of stressor controllability on diurnal physiological rhythms.

    Science.gov (United States)

    Thompson, Robert S; Christianson, John P; Maslanik, Thomas M; Maier, Steve F; Greenwood, Benjamin N; Fleshner, Monika

    2013-03-15

    Disruptions in circadian and diurnal rhythms are associated with stress-related psychiatric disorders and stressor exposure can disrupt these rhythms. The controllability of the stressor can modulate various behavioral and neurochemical responses to stress. Uncontrollable, but not controllable, stress produces behaviors in rats that resemble symptoms of anxiety and depression. Whether acute stress-induced disruptions in physiological rhythms are sensitive to controllability of the stressor, however, remains unknown. To examine the role of controllability in diurnal rhythm disruption, adult male Sprague-Dawley rats were implanted with Data Sciences International (DSI) biotelemetry devices. Real-time measurements were obtained before, during and after exposure to a controllable or yoked uncontrollable stressor. Controllable and uncontrollable stress equally disrupted diurnal rhythms of locomotor activity and body temperature but not heart rate. The diurnal heart rate the day following stressor exposure was flattened to a greater extent and was significantly higher in rats with control over stress suggesting a relationship between stressor controllability and the heart rate response. Our results are consistent with the conclusion that acute stress-induced disruptions in diurnal physiological rhythms likely contribute little to the behavioral and affective consequences of stress that are sensitive to stressor controllability.

  20. Progress in Research on Diurnal and Semidiurnal Earth Rotation Change

    Science.gov (United States)

    Xu, Xueqing

    2015-08-01

    We mainly focus on the progress of research on high frequency changes in the earth rotation. Firstly, we review the development course and main motivating factors of the diurnal and semidiurnal earth rotation change. In recent decades, earth orientation has been monitored with increasing accuracy by advanced space-geodetic techniques, including lunar and satellite laser ranging, very long baseline interferometry and the global positioning system. We are able to obtain the Earth Rotation Parameters (ERP, polar motion and rotation rate changes) by even 1 to 2 hours observation data, form which obvious diurnal and semidiurnal signals can be detected, and compare them with the predicted results by the ocean model. Both the amplitude and phase are in good agreement in the main diurnal and semidiurnal wave frequency, especially for the UT1, whose compliance is 90%, and 60% for polar motion, there are 30% motivating factor of the diurnal and semidiurnal polar motion have not been identified. Then we comprehensively review the different types of global ocean tidal correction models since the last eighties century, as well as the application research on diurnal and semidiurnal polar motion and UT1, the current ocean tidal correction models have 10% to 20% uncertainty, and need for further refinement.

  1. The Photometric Classification Server for Pan-STARRS1

    Science.gov (United States)

    Saglia, R. P.; Tonry, J. L.; Bender, R.; Greisel, N.; Seitz, S.; Senger, R.; Snigula, J.; Phleps, S.; Wilman, D.; Bailer-Jones, C. A. L.; Klement, R. J.; Rix, H.-W.; Smith, K.; Green, P. J.; Burgett, W. S.; Chambers, K. C.; Heasley, J. N.; Kaiser, N.; Magnier, E. A.; Morgan, J. S.; Price, P. A.; Stubbs, C. W.; Wainscoat, R. J.

    2012-02-01

    The Pan-STARRS1 survey is obtaining multi-epoch imaging in five bands (g P1 r P1 i P1 z P1 y P1) over the entire sky north of declination -30 deg. We describe here the implementation of the Photometric Classification Server (PCS) for Pan-STARRS1. PCS will allow the automatic classification of objects into star/galaxy/quasar classes based on colors and the measurement of photometric redshifts for extragalactic objects, and will constrain stellar parameters for stellar objects, working at the catalog level. We present tests of the system based on high signal-to-noise photometry derived from the Medium-Deep Fields of Pan-STARRS1, using available spectroscopic surveys as training and/or verification sets. We show that the Pan-STARRS1 photometry delivers classifications and photometric redshifts as good as the Sloan Digital Sky Survey (SDSS) photometry to the same magnitude limits. In particular, our preliminary results, based on this relatively limited data set down to the SDSS spectroscopic limits, and therefore potentially improvable, show that stars are correctly classified as such in 85% of cases, galaxies in 97%, and QSOs in 84%. False positives are less than 1% for galaxies, ≈19% for stars, and ≈28% for QSOs. Moreover, photometric redshifts for 1000 luminous red galaxies up to redshift 0.5 are determined to 2.4% precision (defined as 1.48 × Median|z phot - z spec|/(1 + z)) with just 0.4% catastrophic outliers and small (-0.5%) residual bias. For bluer galaxies up to the same redshift, the residual bias (on average -0.5%) trend, percentage of catastrophic failures (1.2%), and precision (4.2%) are higher, but still interestingly small for many science applications. Good photometric redshifts (to 5%) can be obtained for at most 60% of the QSOs of the sample. PCS will create a value-added catalog with classifications and photometric redshifts for eventually many millions of sources.

  2. Main diurnal cycle pattern of rainfall in East Java

    Science.gov (United States)

    Rais, Achmad Fahruddin; Yunita, Rezky

    2017-08-01

    The diurnal cycle pattern of rainfall was indicated as an intense feature in East Java. The research of diurnal cycle generally was only based on satellite estimation which had limitations in accuracy and temporal resolution. The hourly rainfall data of Climate Prediction Center Morphing Technique (CMORPH) and gauge were blended using the best correction method between transformation distribution (DT) and quantile mapping (QM) to increase the accuracy. We used spatiotemporal composite to analyse the concentration patterns of maximum rainfall and principal component analysis (PCA) to identify the spatial and temporal dominant patterns of diurnal rainfall. QM was corrected CMORPH data since it was best method. The eastern region of East Java had a rainfall peak at 14 local time (LT) and the western region had a rainfall peak at 16 LT.

  3. Seasonal variation in diurnal atmospheric grass pollen concentration profiles

    DEFF Research Database (Denmark)

    Peel, Robert George; Ørby, Pia Viuf; Skjøth, Carsten Ambelas

    2014-01-01

    In this study, the diurnal atmospheric grass pollen concentration profile within the Danish city of Aarhus was shown to change in a systematic manner as the pollen season progressed. Although diurnal grass pollen profiles can differ greatly from day-to-day, it is common practice to establish...... the time of day when peak concentrations are most likely to occur using seasonally averaged diurnal profiles. Atmospheric pollen loads are highly dependent upon emissions, and different species of grass are known to flower and emit pollen at different times of the day and during different periods...... of the pollen season. Pollen concentrations are also influenced by meteorological factors - directly through those parameters that govern pollen dispersion and transport, and indirectly through the weather-driven flowering process. We found that three different profiles dominated the grass pollen season...

  4. Paradoxical diurnal cortisol changes in neonates suggesting preservation of foetal adrenal rhythms

    Science.gov (United States)

    Kinoshita, Masahiro; Iwata, Sachiko; Okamura, Hisayoshi; Saikusa, Mamoru; Hara, Naoko; Urata, Chihoko; Araki, Yuko; Iwata, Osuke

    2016-01-01

    Studies suggested the presence of foetal adrenal rhythms of cortisol, which are entrained in antiphase to maternal rhythms. In contrast, neonates are thought to have no adrenal rhythm until 2–3 months after birth. To test the hypothesis that a foetal-type adrenal rhythm is preserved after birth, saliva samples were collected from 65 preterm/term infants during hospital stay (30–40 weeks corrected age) at 10:00 and 19:00 h. Cortisol levels were assessed for their diurnal difference and dependence on antenatal/postnatal clinical variables. Cortisol levels were lower during periods 15–28 days and >28 days than ≤5 days of life. Lower cortisol was associated with pregnancy-induced hypertension (PIH), gestational age cortisol was associated with vaginal delivery and non-invasive ventilation support at saliva collection. PIH and non-invasive mechanical ventilation at saliva collection were associated with cortisol levels even after adjustment for postnatal age. Cortisol levels were higher in the evening than in the morning, which was unassociated with gestational and postnatal age. Higher cortisol levels in the evening suggest the preservation of a foetal-type diurnal rhythm. Cortisol levels are associated with intrinsic and extrinsic variables, such as PIH, delivery mode, gestational age, and respiratory conditions. PMID:27752095

  5. Effects of diurnal temperature range and drought on wheat yield in Spain

    Science.gov (United States)

    Hernandez-Barrera, S.; Rodriguez-Puebla, C.; Challinor, A. J.

    2017-07-01

    This study aims to provide new insight on the wheat yield historical response to climate processes throughout Spain by using statistical methods. Our data includes observed wheat yield, pseudo-observations E-OBS for the period 1979 to 2014, and outputs of general circulation models in phase 5 of the Coupled Models Inter-comparison Project (CMIP5) for the period 1901 to 2099. In investigating the relationship between climate and wheat variability, we have applied the approach known as the partial least-square regression, which captures the relevant climate drivers accounting for variations in wheat yield. We found that drought occurring in autumn and spring and the diurnal range of temperature experienced during the winter are major processes to characterize the wheat yield variability in Spain. These observable climate processes are used for an empirical model that is utilized in assessing the wheat yield trends in Spain under different climate conditions. To isolate the trend within the wheat time series, we implemented the adaptive approach known as Ensemble Empirical Mode Decomposition. Wheat yields in the twenty-first century are experiencing a downward trend that we claim is a consequence of widespread drought over the Iberian Peninsula and an increase in the diurnal range of temperature. These results are important to inform about the wheat vulnerability in this region to coming changes and to develop adaptation strategies.

  6. Observations of seasonal and diurnal glacier velocities at Mount Rainier, Washington using terrestrial radar interferometry

    Directory of Open Access Journals (Sweden)

    K. E. Allstadt

    2015-07-01

    Full Text Available We present spatially continuous velocity maps using repeat terrestrial radar interferometry (TRI measurements to examine seasonal and diurnal dynamics of alpine glaciers at Mount Rainier, Washington. We show that the Nisqually and Emmons glaciers have small slope-parallel velocities near the summit (−1, high velocities over their upper and central regions (1.0–1.5 m day−1, and stagnant debris-covered regions near the terminus (−1. Velocity uncertainties are as low as ±0.02–0.08 m day−1. We document a large seasonal velocity decrease of 0.2–0.7 m day−1 (−25 to −50 % from July to November for most of the Nisqually glacier, excluding the icefall, suggesting significant seasonal subglacial water storage under most of the glacier. We did not detect diurnal variability above the noise level. Preliminary 2-D ice flow modeling using TRI velocities suggests that sliding accounts for roughly 91 and 99 % of the July velocity field for the Emmons and Nisqually glaciers, respectively. We validate our observations against recent in situ velocity measurements and examine the long-term evolution of Nisqually glacier dynamics through comparisons with historical velocity data. This study shows that repeat TRI measurements with > 10 km range can be used to investigate spatial and temporal variability of alpine glacier dynamics over large areas, including hazardous and inaccessible areas.

  7. Galaxy clustering with photometric surveys using PDF redshift information

    Science.gov (United States)

    Asorey, J.; Carrasco Kind, M.; Sevilla-Noarbe, I.; Brunner, R. J.; Thaler, J.

    2016-06-01

    Photometric surveys produce large-area maps of the galaxy distribution, but with less accurate redshift information than is obtained from spectroscopic methods. Modern photometric redshift (photo-z) algorithms use galaxy magnitudes, or colours, that are obtained through multiband imaging to produce a probability density function (PDF) for each galaxy in the map. We used simulated data to study the effect of using different photo-z estimators to assign galaxies to redshift bins in order to compare their effects on angular clustering and galaxy bias measurements. We found that if we use the entire PDF, rather than a single-point (mean or mode) estimate, the deviations are less biased, especially when using narrow redshift bins. When the redshift bin widths are Δz = 0.1, the use of the entire PDF reduces the typical measurement bias from 5 per cent, when using single point estimates, to 3 per cent.

  8. Galaxy clustering with photometric surveys using PDF redshift information

    CERN Document Server

    Asorey, J; Sevilla-Noarbe, I; Brunner, R J; Thaler, J

    2016-01-01

    Photometric surveys produce large-area maps of the galaxy distribution, but with less accurate redshift information than is obtained from spectroscopic methods. Modern photometric redshift (photo-z) algorithms use galaxy magnitudes, or colors, that are obtained through multi-band imaging to produce a probability density function (PDF) for each galaxy in the map. We used simulated data to study the effect of using different photo-z estimators to assign galaxies to redshift bins in order to compare their effects on angular clustering and galaxy bias measurements. We found that if we use the entire PDF, rather than a single-point (mean or mode) estimate, the deviations are less biased, especially when using narrow redshift bins. When the redshift bin widths are $\\Delta z=0.1$, the use of the entire PDF reduces the typical measurement bias from 5%, when using single point estimates, to 3%.

  9. DNF - Galaxy photometric redshift by Directional Neighbourhood Fitting

    Science.gov (United States)

    De Vicente, J.; Sánchez, E.; Sevilla-Noarbe, I.

    2016-07-01

    Wide field images taken in several photometric bands allow simultaneous measurement of redshifts for thousands of galaxies. A variety of algorithms to make this measurement have appeared in the last few years, the majority of which can be classified as either template- or training-based methods. Among the latter, nearest neighbour estimators stand out as one of the most successful, in terms of both precision and the quality of error estimation. In this paper we describe the Directional Neighbourhood Fitting (DNF) algorithm based on the following: a new neighbourhood metric (Directional Neighbourhood), a photo-z estimation strategy (Neighbourhood Fitting) and a method for generating the photo-z probability distribution function. We compare DNF with other well-known empirical photometric redshift tools using different public data sets (Sloan Digital Sky Survey, VIMOS VLT Deep Survey and Photo-z Accuracy Testing). DNF achieves high-quality results with reliable error.

  10. Exploring the SDSS Photometric Galaxies with Clustering Redshifts

    CERN Document Server

    Rahman, Mubdi; Ménard, Brice; Scranton, Ryan; Schmidt, Samuel J; Morrison, Christopher B; Budavári, Tamás

    2015-01-01

    We apply clustering-based redshift inference to all extended sources from the Sloan Digital Sky Survey photometric catalogue, down to magnitude r = 22. We map the relationships between colours and redshift, without assumption of the sources' spectral energy distributions (SED). We identify and locate star-forming, quiescent galaxies, and AGN, as well as colour changes due to spectral features, such as the 4000 \\AA{} break, redshifting through specific filters. Our mapping is globally in good agreement with colour-redshift tracks computed with SED templates, but reveals informative differences, such as the need for a lower fraction of M-type stars in certain templates. We compare our clustering-redshift estimates to photometric redshifts and find these two independent estimators to be in good agreement at each limiting magnitude considered. Finally, we present the global clustering-redshift distribution of all Sloan extended sources, showing objects up to z ~ 0.8. While the overall shape agrees with that infer...

  11. Modelling multimodal photometric redshift regression with noisy observations

    CERN Document Server

    Kügler, S D

    2016-01-01

    In this work, we are trying to extent the existing photometric redshift regression models from modeling pure photometric data back to the spectra themselves. To that end, we developed a PCA that is capable of describing the input uncertainty (including missing values) in a dimensionality reduction framework. With this "spectrum generator" at hand, we are capable of treating the redshift regression problem in a fully Bayesian framework, returning a posterior distribution over the redshift. This approach allows therefore to approach the multimodal regression problem in an adequate fashion. In addition, input uncertainty on the magnitudes can be included quite naturally and lastly, the proposed algorithm allows in principle to make predictions outside the training values which makes it a fascinating opportunity for the detection of high-redshifted quasars.

  12. Calibrating photometric redshift distributions with cross-correlations

    CERN Document Server

    Schulz, A E

    2009-01-01

    The next generation of proposed galaxy surveys will increase the number of galaxies with photometric redshifts by two orders of magnitude, drastically expanding both redshift range and detection threshold from the current state of the art. Obtaining spectra for a fair sub-sample of this new data could be cumbersome and expensive. However, adequate calibration of the true redshift distribution of galaxies is vital to tapping the potential of these surveys. We examine a promising alternative to direct spectroscopic follow up: calibration of the redshift distribution of photometric galaxies via cross-correlation with an overlapping spectroscopic survey whose members trace the same density field. We review the theory, develop a pipeline, apply it to mock data from N-body simulations, and examine the properties of this redshift distribution estimator. We demonstrate that the method is effective, but the estimator is weakened by two factors. 1) The correlation function of the spectroscopic sample must be measured i...

  13. Multi-parameter estimating photometric redshifts with artificial neural networks

    CERN Document Server

    Li, L; Zhao, Y; Yang, D; Li, Lili; Zhang, Yanxia; Zhao, Yongheng; Yang, Dawei

    2006-01-01

    We calculate photometric redshifts from the Sloan Digital Sky Survey Data Release 2 Galaxy Sample using artificial neural networks (ANNs). Different input patterns based on various parameters (e.g. magnitude, color index, flux information) are explored and their performances for redshift prediction are compared. For ANN technique, any parameter may be easily incorporated as input, but our results indicate that using reddening magnitude produces photometric redshift accuracies often better than the Petrosian magnitude or model magnitude. Similarly, the model magnitude is also superior to Petrosian magnitude. In addition, ANNs also show better performance when the more effective parameters increase in the training set. Finally, the method is tested on a sample of 79, 346 galaxies from the SDSS DR2. When using 19 parameters based on the reddening magnitude, the rms error in redshift estimation is sigma(z)=0.020184. The ANN is highly competitive tool when compared with traditional template-fitting methods where a...

  14. A Sparse Gaussian Process Framework for Photometric Redshift Estimation

    CERN Document Server

    Almosallam, Ibrahim A; Jarvis, Matt J; Roberts, Stephen J

    2015-01-01

    Accurate photometric redshift are a lynchpin for many future experiments to pin down the cosmological model and for studies of galaxy evolution. In this study, a novel sparse regression framework for photometric redshift estimation is presented. Data from a simulated survey was used to train and test the proposed models. We show that approaches which include careful data preparation and model design offer a significant improvement in comparison with several competing machine learning algorithms. Standard implementation of most regression algorithms has as the objective the minimization of the sum of squared errors. For redshift inference, however, this induces a bias in the posterior mean of the output distribution, which can be problematic. In this paper we optimize to directly target minimizing $\\Delta z = (z_\\textrm{s} - z_\\textrm{p})/(1+z_\\textrm{s})$ and address the bias problem via a distribution-based weighting scheme, incorporated as part of the optimization objective. The results are compared with ot...

  15. A Photometric Machine-Learning Method to Infer Stellar Metallicity

    Science.gov (United States)

    Miller, Adam A.

    2015-01-01

    Following its formation, a star's metal content is one of the few factors that can significantly alter its evolution. Measurements of stellar metallicity ([Fe/H]) typically require a spectrum, but spectroscopic surveys are limited to a few x 10(exp 6) targets; photometric surveys, on the other hand, have detected > 10(exp 9) stars. I present a new machine-learning method to predict [Fe/H] from photometric colors measured by the Sloan Digital Sky Survey (SDSS). The training set consists of approx. 120,000 stars with SDSS photometry and reliable [Fe/H] measurements from the SEGUE Stellar Parameters Pipeline (SSPP). For bright stars (g' machine-learning method is similar to the scatter in [Fe/H] measurements from low-resolution spectra..

  16. Photometric Redshift with Bayesian Priors on Physical Properties of Galaxies

    CERN Document Server

    Tanaka, Masayuki

    2015-01-01

    We present a proof-of-concept analysis of photometric redshifts with Bayesian priors on physical properties of galaxies. This concept is particularly suited for upcoming/on-going large imaging surveys, in which only several broad-band filters are available and it is hard to break some of the degeneracies in the multi-color space. We construct model templates of galaxies using a stellar population synthesis code and apply Bayesian priors on physical properties such as stellar mass and star formation rate. These priors are a function of redshift and they effectively evolve the templates with time in an observationally motivated way. We demonstrate that the priors help reduce the degeneracy and deliver significantly improved photometric redshifts. Furthermore, we show that a template error function, which corrects for systematic flux errors in the model templates as a function of rest-frame wavelength, delivers further improvements. One great advantage of our technique is that we simultaneously measure redshifts...

  17. The Photometric Properties of Galaxies in the Early Universe

    CERN Document Server

    Wilkins, Stephen M; Di-Matteo, Tiziana; Croft, Rupert; Stanway, Elizabeth R; Bunker, Andrew; Waters, Dacen; Lovell, Christopher

    2016-01-01

    We use the large cosmological hydro-dynamic simulation BlueTides to predict the photometric properties of galaxies during the epoch of reionisation ($z=8-15$). These properties include the rest-frame UV to near-IR broadband spectral energy distributions, the Lyman continuum photon production, the UV star formation rate calibration, and intrinsic UV continuum slope. In particular we focus on exploring the effect of various modelling assumptions, including the assumed choice of stellar population synthesis model, initial mass function, and the escape fraction of Lyman continuum photons, upon these quantities. We find that these modelling assumptions can have a dramatic effect on photometric properties leading to consequences for the accurate determination of physical properties from observations. For example, at $z=8$ we predict that nebular emission can account for up-to $50\\%$ of the rest-frame $R$-band luminosity, while the choice of stellar population synthesis model can change the Lyman continuum productio...

  18. Photometric Supernova Cosmology with BEAMS and SDSS-II

    CERN Document Server

    Hlozek, Renée; Bassett, Bruce; Smith, Mat; Newling, James; Varughese, Melvin; Kessler, Rick; Bernstein, Joe; Campbell, Heather; Dilday, Ben; Falck, Bridget; Frieman, Joshua; Kulhmann, Steve; Lampeitl, Hubert; Marriner, John; Nichol, Robert C; Riess, Adam G; Sako, Masao; Schneider, Donald P

    2011-01-01

    Supernova cosmology without spectroscopic confirmation is an exciting new frontier which we address here with the Bayesian Estimation Applied to Multiple Species (BEAMS) algorithm and the full three years of data from the Sloan Digital Sky Survey II Supernova Survey (SDSS-II SN). BEAMS is a Bayesian framework for using data from multiple species in statistical inference when one has the probability that each data point belongs to a given species, corresponding in this context to different types of supernovae with their probabilities derived from their multi-band lightcurves. We run the BEAMS algorithm on both Gaussian and more realistic SNANA simulations with of order 10^4 supernovae, testing the algorithm against various pitfalls one might expect in the new and somewhat uncharted territory of photometric supernova cosmology. We compare the performance of BEAMS to that of both mock spectroscopic surveys and photometric samples which have been cut using typical selection criteria. The latter typically are eith...

  19. The Photometric Software for Transits (PhoS-T)

    Science.gov (United States)

    Mislis, D.; Heller, R.; Fernandez, J.; Seemann, U.; Ioannidis, P.; Avdellidou, C.

    2012-01-01

    We present the Photometric Software for Transits (Phos-T), a user-friendly stand-alone astronomical software built to study in detail photometric data of transiting extra-solar planets. Through a simple and clean graphical environment, PhoS-T can perform data calibration, point-source differential photometry, and transit light curve modelling. Here we present a detailed description of the software, together with the analysis of a recent transit of the extra-solar planet HAT-P-19b, observed from Holomon astronomical station. The results obtained using PhoS-T are in good agreement with previous works, and provide a precise time-of-transit for HAT-P-19b.

  20. Photometric redshifts for supernovae Ia in the Supernova Legacy Survey

    CERN Document Server

    Palanque-Delabrouille, Nathalie; Pascal, S; Rich, J; Guy, J; Bazin, G; Astier, P; Balland, C; Basa, S; Carlberg, R G; Conley, A; Fouchez, D; Hardin, D; Hook, I M; Howell, D A; Pain, R; Perrett, K; Pritchet, C J; Regnault, N; Sullivan, M

    2009-01-01

    We present a method using the SALT2 light curve fitter to determine the redshift of Type Ia supernovae in the Supernova Legacy Survey (SNLS) based on their photometry in g', r', i' and z'. On 289 supernovae of the first three years of SNLS data, we obtain a precision $\\sigma_{\\Delta z/(1+z)} = 0.022$ on average up to a redshift of 1.0, with a higher precision of 0.016 for z0.45. The rate of events with $|\\Delta z|/(1+z)>0.15$ (catastrophic errors) is 1.4%. Both the precision and the rate of catastrophic errors are better than what can be currently obtained using host galaxy photometric redshifts. Photometric redshifts of this precision may be useful for future experiments which aim to discover up to millions of supernovae Ia but without spectroscopy for most of them.

  1. Measuring photometric redshifts using galaxy images and Deep Neural Networks

    Science.gov (United States)

    Hoyle, B.

    2016-07-01

    We propose a new method to estimate the photometric redshift of galaxies by using the full galaxy image in each measured band. This method draws from the latest techniques and advances in machine learning, in particular Deep Neural Networks. We pass the entire multi-band galaxy image into the machine learning architecture to obtain a redshift estimate that is competitive, in terms of the measured point prediction metrics, with the best existing standard machine learning techniques. The standard techniques estimate redshifts using post-processed features, such as magnitudes and colours, which are extracted from the galaxy images and are deemed to be salient by the user. This new method removes the user from the photometric redshift estimation pipeline. However we do note that Deep Neural Networks require many orders of magnitude more computing resources than standard machine learning architectures, and as such are only tractable for making predictions on datasets of size ≤50k before implementing parallelisation techniques.

  2. Assessing the Photometric Calibration of the ASAS Survey

    Science.gov (United States)

    Berdnikov, L. N.; Dambis, A. K.

    2016-05-01

    We compare bona fide calibrated mean VIC magnitudes of several hundred stars found in the CCD frames taken in 2012 during our photometric observations of 109 Cepheids and RR Lyrae type stars made at the South African Astronomical Observatory to the corresponding mean VIC magnitudes measured in the course of the ASAS survey to assess the quality of ASAS photometry and derive the appropriate transformation equations. We conclude that as far as the only serious caveat due to photometric errors, which range from ˜ 0.05m for relatively bright stars to about ˜ 0.15m for ˜ 14m stars and translates into extra fractional distance error of 0.025-0.07.

  3. MYRaf: A new Approach with IRAF for Astronomical Photometric Reduction

    Science.gov (United States)

    Kilic, Y.; Shameoni Niaei, M.; Özeren, F. F.; Yesilyaprak, C.

    2016-12-01

    In this study, the design and some developments of MYRaf software for astronomical photometric reduction are presented. MYRaf software is an easy to use, reliable, and has a fast IRAF aperture photometry GUI tools. MYRaf software is an important step for the automated software process of robotic telescopes, and uses IRAF, PyRAF, matplotlib, ginga, alipy, and Sextractor with the general-purpose and high-level programming language Python and uses the QT framework.

  4. A sparse Gaussian process framework for photometric redshift estimation

    Science.gov (United States)

    Almosallam, Ibrahim A.; Lindsay, Sam N.; Jarvis, Matt J.; Roberts, Stephen J.

    2016-01-01

    Accurate photometric redshifts are a lynchpin for many future experiments to pin down the cosmological model and for studies of galaxy evolution. In this study, a novel sparse regression framework for photometric redshift estimation is presented. Synthetic data set simulating the Euclid survey and real data from SDSS DR12 are used to train and test the proposed models. We show that approaches which include careful data preparation and model design offer a significant improvement in comparison with several competing machine learning algorithms. Standard implementations of most regression algorithms use the minimization of the sum of squared errors as the objective function. For redshift inference, this induces a bias in the posterior mean of the output distribution, which can be problematic. In this paper, we directly minimize the target metric Δz = (zs - zp)/(1 + zs) and address the bias problem via a distribution-based weighting scheme, incorporated as part of the optimization objective. The results are compared with other machine learning algorithms in the field such as artificial neural networks (ANN), Gaussian processes (GPs) and sparse GPs. The proposed framework reaches a mean absolute Δz = 0.0026(1 + zs), over the redshift range of 0 ≤ zs ≤ 2 on the simulated data, and Δz = 0.0178(1 + zs) over the entire redshift range on the SDSS DR12 survey, outperforming the standard ANNz used in the literature. We also investigate how the relative size of the training sample affects the photometric redshift accuracy. We find that a training sample of >30 per cent of total sample size, provides little additional constraint on the photometric redshifts, and note that our GP formalism strongly outperforms ANNz in the sparse data regime for the simulated data set.

  5. Asteroid phase curves from Lowell observatory photometric database

    Directory of Open Access Journals (Sweden)

    D. A. Oszkiewicz

    2011-09-01

    Full Text Available We present results obtained from processing large photometric data base. We make use of low-precision (generally rounded to 0.1 mag and low-accuracy (rms magnitude uncertainties of ±0.2 to 0.3 mag data obtained from the Minor Planet Center and modified at Lowell Observatory. We explore first correlations between slope parameter(s and albedo, and second distributions of slope parameter(s in asteroid families and taxa.

  6. The photometric method of extrasolar planet detection revisited

    Science.gov (United States)

    Hale, Alan; Doyle, Laurance R.

    1994-01-01

    We investigate the geometry concerning the photometric method of extrasolar planet detection, i.e., the detection of dimunition of a parent star's brightness during a planetary transit. Under the assumption that planetary orbital inclinations can be defined by a Gaussian with a sigma of 10 deg centered on the parent star's equatorial plane, Monte Carlo simulations suggest that for a given star observed at an inclination of exactly 90 deg, the probability of at least one Earth-sized or larger planet being suitably placed for transits is approximately 4%. This probability drops to 3% for a star observed at an inclination of 80 deg, and is still approximately 0.5% for a star observed at an inclination of 60 deg. If one can select 100 stars with a pre-determined inclination equal or greater than 80 deg, the probability of at least one planet being suitably configured for transits is 95%. The majority of transit events are due to planets in small-a orbits similar to the Earth and Venus; thus, the photometric method in principle is the method best suited for the detection of Earthlike planets. The photometric method also allows for testing whether or not planets can exist within binary systems. This can ge done by selecting binary systems observed at high orbital inclinations, both eclipsing binaries and wider visual binaries. For a 'real-world' example, we look at the alpha Centauri system (i = 79.2 deg). If we assume that the equatorial planes of both components coincide with the system's orbital plane, Monte Carlo simulations suggest that the probability of at least one planet (of either component) being suitably configured for transits is approximately 8%. In conclusion, we present a non-exhaustive list of solar-type stars, both single and within binary systems, which exhibit a high equatorial inclination. These objects may be considered as preliminary candidates for planetary searches via the photometric method.

  7. Diurnality, nocturnality, and the evolution of primate visual systems.

    Science.gov (United States)

    Ankel-Simons, F; Rasmussen, D T

    2008-01-01

    Much of the recent research on the evolution of primate visual systems has assumed that a minimum number of shifts have occurred in circadian activity patterns over the course of primate evolution. The evolutionary origins of key higher taxonomic groups have been interpreted by some researchers as a consequence of a rare shift from nocturnality to diurnality (e.g., Anthropoidea) or from diurnality to nocturnality (e.g., Tarsiidae). Interpreting the evolution of primate visual systems with an ecological approach without parsimony constraints suggests that the evolutionary transitions in activity pattern are more common than what would be allowed by parsimony models, and that such transitions are probably less important in the origin of higher level taxa. The analysis of 17 communities of primates distributed widely around the world and through geological time shows that primate communities consistently contain both nocturnal and diurnal forms, regardless of the taxonomic sources of the communities. This suggests that primates in a community will adapt their circadian pattern to fill empty diurnal or nocturnal niches. Several evolutionary transitions from one pattern to the other within narrow taxonomic groups are solidly documented, and these cases probably represent a small fraction of such transitions throughout the Cenozoic. One or more switches have been documented among platyrrhine monkeys, Malagasy prosimians, Eocene omomyids, Eocene adapoids, and early African anthropoids, with inconclusive but suggestive data within tarsiids. The interpretation of living and extinct primates as fitting into one of two diarhythmic categories is itself problematic, because many extant primates show significant behavioral activity both nocturnally and diurnally. Parsimony models routinely interpret ancestral primates to have been nocturnal, but analyses of morphological and genetic data indicate that they may have been diurnal, or that early primate radiations were likely to

  8. Trial of Oral Metoclopramide on Diurnal Bruxism of Brain Injury

    Science.gov (United States)

    Yi, Ho Sung; Seo, Mi Ri

    2013-01-01

    Bruxism is a diurnal or nocturnal parafunctional activity that includes tooth clenching, bracing, gnashing, and grinding. The dopaminergic system seems to be the key pathophysiology of bruxism and diminution of dopaminergic transmission at the prefrontal cortex seems to induce it. We report two patients with diurnal bruxism in whom a bilateral frontal lobe injury resulted from hemorrhagic stroke or traumatic brain injury. These patients' bruxism was refractory to bromocriptine but responded to low-dose metoclopramide therapy. We propose that administering low doses of metoclopramide is possibly a sound method for treating bruxism in a brain injury patient with frontal lobe hypoperfusion on positron emission tomography imaging. PMID:24466522

  9. Calibration of LSST Instrumental and Atmospheric Photometric Passbands

    Energy Technology Data Exchange (ETDEWEB)

    Burke, David L.; /SLAC; Axelrod, T.; /Arizona U., Astron. Dept. - Steward Observ.; Barrau, Aurelien; Baumont, Sylvain; /LPSC, Grenoble; Blondin, Stephane; /Marseille, CPPM; Claver, Chuck; /NOAO, Tucson; Gorecki, Alexia; /LPSC, Grenoble; Ivezic, Zeljko; Jones, Lynne; /Washington U., Seattle, Astron. Dept.; Krabbendam, Victor; Liang, Ming; Saha, Abhijit; /NOAO, Tucson; Smith, Allyn; /Austin Peay State U.; Smith, R.Chris; /Cerro-Tololo InterAmerican Obs.; Stubbs, Christopher W.; /Harvard-Smithsonian Ctr. Astrophys.

    2011-07-06

    The Large Synoptic Survey Telescope (LSST) will continuously image the entire sky visible from Cerro Pachon in northern Chile every 3-4 nights throughout the year. The LSST will provide data for a broad range of science investigations that require better than 1% photometric precision across the sky (repeatability and uniformity) and a similar accuracy of measured broadband color. The fast and persistent cadence of the LSST survey will significantly improve the temporal sampling rate with which celestial events and motions are tracked. To achieve these goals, and to optimally utilize the observing calendar, it will be necessary to obtain excellent photometric calibration of data taken over a wide range of observing conditions - even those not normally considered 'photometric'. To achieve this it will be necessary to routinely and accurately measure the full optical passband that includes the atmosphere as well as the instrumental telescope and camera system. The LSST mountain facility will include a new monochromatic dome illumination projector system to measure the detailed wavelength dependence of the instrumental passband for each channel in the system. The facility will also include an auxiliary spectroscopic telescope dedicated to measurement of atmospheric transparency at all locations in the sky during LSST observing. In this paper, we describe these systems and present laboratory and observational data that illustrate their performance.

  10. Exhausting the Information: Novel Bayesian Combination of Photometric Redshift PDFs

    CERN Document Server

    Kind, M Carrasco

    2014-01-01

    The estimation and utilization of photometric redshift (photo-z) PDFs has become increasingly important over the last few years. Primarily this is because of the prominent role photo-z PDFs play in enabling photometric survey data to be used to make cosmological constraints, especially when compared to single estimates. Currently there exist a wide variety of algorithms to compute photo-z's, each with their own strengths and weaknesses. In this paper, we present a novel and efficient Bayesian framework that combines the results from different photo-z techniques into a more powerful and robust estimate by maximizing the information from the photometric data. To demonstrate this we use a supervised machine learning technique based on prediction trees and a random forest, an unsupervised method based on self organizing maps and a random atlas, and a standard template fitting method but can be easily extend to other existing techniques. We use data from the DEEP2 survey and more than $10^6$ galaxies from the SDSS...

  11. Photometric monitoring of the young star Par 1724 in Orion

    Science.gov (United States)

    Neuhäuser, R.; Koeltzsch, A.; Raetz, St.; Schmidt, T. O. B.; Mugrauer, M.; Young, N.; Bertoldi, F.; Roell, T.; Eisenbeiss, T.; Hohle, M. M.; Vaňko, M.; Ginski, C.; Rammo, W.; Moualla, M.; Broeg, C.

    2009-05-01

    We report new photometric observations of the ˜ 200 000 year old naked weak-line run-away T Tauri star Par 1724, located north of the Trapezium cluster in Orion. We observed in the broad band filters B, V, R, and I using the 90 cm Dutch telescope on La Silla, the 80 cm Wendelstein telescope, and a 25 cm telescope of the University Observatory Jena in Großschwabhausen near Jena. The photometric data in V and R are consistent with a ˜ 5.7 day rotation period due to spots, as observed before between 1960ies and 2000. Also, for the first time, we present evidence for a long-term 9 or 17.5 year cycle in photometric data (V band) of such a young star, a cycle similar to that to of the Sun and other active stars. Based on observations obtained with telescopes of the University Observatory Jena, which is operated by the Astrophysical Institute of the Friedrich-Schiller-University; a telescope of the University Observatory Munich on Mount Wendelstein, the 0.9m ESO-Dutch telescope on La Silla, Chile, and with the All Sky Automated Survey (ASAS) project (www.astrouw.edu.pl/asas).

  12. Photometric redshifts for the SDSS Data Release 12

    CERN Document Server

    Beck, Róbert; Budavári, Tamás; Szalay, Alexander S; Csabai, István

    2016-01-01

    We present the methodology and data behind the photometric redshift database of the Sloan Digital Sky Survey Data Release 12 (SDSS DR12). We adopt a hybrid technique, empirically estimating the redshift via local regression on a spectroscopic training set, then fitting a spectrum template to obtain K-corrections and absolute magnitudes. The SDSS spectroscopic catalog was augmented with data from other, publicly available spectroscopic surveys to mitigate target selection effects. The training set is comprised of $1,976,978$ galaxies, and extends up to redshift $z\\approx 0.8$, with a useful coverage of up to $z\\approx 0.6$. We provide photometric redshifts and realistic error estimates for the $208,474,076$ galaxies of the SDSS primary photometric catalog. We achieve an average bias of $\\overline{\\Delta z_{\\mathrm{norm}}} = -0.0012$, a standard deviation of $\\sigma \\left(\\Delta z_{\\mathrm{norm}}\\right)=0.0249$, and a $3\\sigma$ outlier rate of $P_o=1.6\\%$ when cross-validating on our training set. The published...

  13. A comprehensive photometric study of the eclipsing binary EP Aurigae

    Science.gov (United States)

    Li, H.-L.; Wei, J.-Y.; Yang, Y.-G.; Li, K.; Zhang, X.-B.

    2015-02-01

    We present new observations for the eclipsing binary EP Aurigae, which were performed by using three small telescopes in China from 2003 December to 2014 January. With the updated 2003 version of the Wilson-Devinney code, the photometric elements were deduced from three sets of light curves. Based on all available eclipsing times, the orbital period changes were investigated. It is discovered that the (O-C) curve may show an existence of light-time effect due to an unseen third body, which was weakly identified by the photometric solution. The modulated period and amplitude of the cyclic variation are P3=71.2(±8.0) yr and A=0.0101(±0.0008) day, respectively. In the co-planar orbit with the binary system, the mass of the third body is M3=0.18(±0.02) M⊙. The photometric results imply that EP Aur is an Algol-type binary with a mass ratio of q=0.831(±0.004). Its primary component almost fills its Roche lobe. Therefore, EP Aur may consist of a normal main-sequence star and a cool Roche-lobe filling subgiant, which may be undergoing rapid mass transfer.

  14. Photometric Study of the Possible Cool Quadruple System PY Virginis

    Science.gov (United States)

    Zhu, L. Y.; Qian, S. B.; Liu, N. P.; Liu, L.; Jiang, L. Q.

    2013-02-01

    Complete CCD photometric light curves in BV(RI)c bands obtained in 2012 for the short-period close binary system PY Virginis are presented. A new photometric analysis with the Wilson—Van Hamme code shows that PY Vir is an A-type marginal contact binary system. The absolute parameters of PY Vir are derived using spectroscopic and photometric solutions. Combining new determined times of minimum light with others published in the literature, the O - C diagram of the binary star is investigated. A periodic variation, with a period of 5.22(±0.05) years and an amplitude of 0.0075(±0.0004) days, was discovered. Since the spectrum of a third component has been detected by Rucinski et al., we consider this cyclic period oscillation to be the result of the light-time effect due to the presence of a third body. This third component may also be a binary itself. Therefore, PY Vir should be a quadruple system composed of two cool-type binary systems. This system is a good astrophysical laboratory to study the formation and evolution of close binaries and multiple systems.

  15. Can Self-Organizing Maps accurately predict photometric redshifts?

    CERN Document Server

    Way, M J

    2012-01-01

    We present an unsupervised machine learning approach that can be employed for estimating photometric redshifts. The proposed method is based on a vector quantization approach called Self--Organizing Mapping (SOM). A variety of photometrically derived input values were utilized from the Sloan Digital Sky Survey's Main Galaxy Sample, Luminous Red Galaxy, and Quasar samples along with the PHAT0 data set from the PHoto-z Accuracy Testing project. Regression results obtained with this new approach were evaluated in terms of root mean square error (RMSE) to estimate the accuracy of the photometric redshift estimates. The results demonstrate competitive RMSE and outlier percentages when compared with several other popular approaches such as Artificial Neural Networks and Gaussian Process Regression. SOM RMSE--results (using $\\Delta$z=z$_{phot}$--z$_{spec}$) for the Main Galaxy Sample are 0.023, for the Luminous Red Galaxy sample 0.027, Quasars are 0.418, and PHAT0 synthetic data are 0.022. The results demonstrate th...

  16. Cosmological parameters from a million photometric redshifts of SDSS LRGs

    CERN Document Server

    Blake, C; Bridle, S; Lahav, O; Blake, Chris; Collister, Adrian; Bridle, Sarah; Lahav, Ofer

    2006-01-01

    We analyze MegaZ-LRG, a new photometric-redshift catalogue of Luminous Red Galaxies (LRGs) based on the imaging data of the Sloan Digital Sky Survey (SDSS) 4th Data Release. MegaZ-LRG, presented in a companion paper, contains > 10^6 photometric redshifts derived with ANNz, an Artificial Neural Network method, constrained by a spectroscopic sub-sample of ~13,000 galaxies obtained by the 2dF-SDSS LRG and Quasar (2SLAQ) survey. The catalogue spans the redshift range 0.4photometric redshift survey. Combining the redshift slices with appropriate covariances, we determine the matter density Omega_m and baryon density Omega_b in the combinations Omega_m h = 0.20+/-0.03 and Omega_b/Omega_m = 0.14+/-0.04. These results are in agreement with and independent of the latest studies of the Cosmic Microwave Background radiation, and their precision is comparable to analyses of conte...

  17. Satellite Type Estination from Ground-based Photometric Observation

    Science.gov (United States)

    Endo, T.; Ono, H.; Suzuki, J.; Ando, T.; Takanezawa, T.

    2016-09-01

    The optical photometric observation is potentially a powerful tool for understanding of the Geostationary Earth Orbit (GEO) objects. At first, we measured in laboratory the surface reflectance of common satellite materials, for example, Multi-layer Insulation (MLI), mono-crystalline silicon cells, and Carbon Fiber Reinforced Plastic (CFRP). Next, we calculated visual magnitude of a satellite by simplified shape and albedo. In this calculation model, solar panels have dimensions of 2 by 8 meters, and the bus area is 2 meters squared with measured optical properties described above. Under these conditions, it clarified the brightness can change the range between 3 and 4 magnitudes in one night, but color index changes only from 1 to 2 magnitudes. Finally, we observed the color photometric data of several GEO satellites visible from Japan multiple times in August and September 2014. We obtained that light curves of GEO satellites recorded in the B and V bands (using Johnson filters) by a ground-base optical telescope. As a result, color index changed approximately from 0.5 to 1 magnitude in one night, and the order of magnitude was not changed in all cases. In this paper, we briefly discuss about satellite type estimation using the relation between brightness and color index obtained from the photometric observation.

  18. A Fourteen-Band Photometric Study of A2443

    Institute of Scientific and Technical Information of China (English)

    Zhong-Lue Wen; Yan-Bin Yang; Qi-Rong Yuan; Xu Zhou; Jun Ma; Zhao-Ji Jiang

    2007-01-01

    We present a multi-color photometric study of the galaxy cluster A2443 (z = 0.108) with the Beijing-Arizona-Taiwan-Connecticut (BATC) system. The spectral energy distributions (SEDs) in 14 intermediate bands are obtained for 5975 detected from ~1deg2 of the BATC images. Color-color diagrams are used for star-galaxy separation, then a photometric redshift technique is applied to the galaxy sample for cluster membership determination. There are 301 galaxies with photometric redshifts between 0.08 and 0.14 determined as member candidates of A2443, including 289 new ones. Based on this enlarged sample, the luminosity function and color magnitude relation of the cluster are studied. With an evolutionary synthesis model, we find that the fainter galaxies tend to have longer time scales of star formation than the brighter ones. Morphologically, we show an elongated spatial distribution associating with the galaxy cluster ZwCl 2224.2+ 1651, which contains more blue galaxies. This result indicates that galaxy cluster ZwCl 2224.2+1651 may be falling into A2443, and cluster-cluster interaction could have triggered star formation activities in ZwCl 2224.2+1651.

  19. Establishment of the NIST flashing-light photometric unit

    Science.gov (United States)

    Ohno, Yoshihiro; Zong, Yuqin

    1997-09-01

    There is a need for accurate measurement of flashing lights for the proper maintenance of aircraft anticollision lights. A large variation in the measured intensities of anticollision lights has been a problem, and thus, NIST has undertaken the task to establish flashing-light photometric standards to provide calibration services in this area. A flashing-light photometric unit [lux second, (lx (DOT) s)] has been realized based on the NIST detector-based candela, using four standard photometers equipped with current integrators. Two different approaches have been taken to calibrate these standard photometers: one based on electrical calibration of the current integrator, and the other based on electronic pulsing of a steady-state photometric standard. The units realized using these two independent methods agreed to within 0.2%. The relative expanded uncertainty (k equals 2) of the standard photometers, in the measurement of the white xenon flash, is estimated to be 0.6%. The standard photometers are characterized for temporal response, linearity, and spectral responsivity, to be used for measurement of xenon flash sources of various waveforms and colors. Calibration services have been established at NIST for flashing-light photometers with white and red anticollision lights.

  20. Evolution of Galaxy Luminosity Function Using Photometric Redshifts

    CERN Document Server

    Ramos, B H F; Benoist, C; da Costa, L N; Maia, M A G; Makler, M; Ogando, R L C; de Simoni, F; Mesquita, A A

    2011-01-01

    We examine the impact of using photometric redshifts for studying the evolution of both the global galaxy luminosity function (LF) and that for different galaxy types. To this end we compare LFs obtained using photometric redshifts from the CFHT Legacy Survey (CFHTLS) D1 field with those from the spectroscopic survey VIMOS VLT Deep Survey (VVDS) comprising ~4800 galaxies. We find that for z<2, in the interval of magnitudes considered by this survey, the LFs obtained using photometric and spectroscopic redshifts show a remarkable agreement. This good agreement led us to use all four Deep fields of CFHTLS comprising ~386000 galaxies to compute the LF of the combined fields and estimate directly the error in the parameters based on field-to-field variation. We find that the characteristic absolute magnitude M* of Schechter fits fades by ~0.7mag from z~1.8 to z~0.3, while the characteristic density phi* increases by a factor of ~4 in the same redshift bin. We use the galaxy classification provided by the templ...

  1. The Photometric Classification Server for Pan-STARRS1

    CERN Document Server

    Saglia, R P; Bender, R; Greisel, N; Seitz, S; Senger, R; Snigula, J; Phleps, S; Wilman, D; Bailer-Jones, C A L; Klement, R J; Rix, H -W; Smith, K; Green, P J; Burgett, W S; Chambers, K C; Heasley, J N; Kaiser, N; Magnier, E A; Morgan, J S; Price, P A; Stubbs, C W; Wainscoat, R J

    2011-01-01

    The Pan-STARRS1 survey is obtaining multi-epoch imaging in 5 bands (gps rps ips zps yps) over the entire sky North of declination -30deg. We describe here the implementation of the Photometric Classification Server (PCS) for Pan-STARRS1. PCS will allow the automatic classification of objects into star/galaxy/quasar classes based on colors, the measurement of photometric redshifts for extragalactic objects, and constrain stellar parameters for stellar objects, working at the catalog level. We present tests of the system based on high signal-to-noise photometry derived from the Medium Deep Fields of Pan-STARRS1, using available spectroscopic surveys as training and/or verification sets. We show that the Pan-STARRS1 photometry delivers classifications and photometric redshifts as good as the Sloan Digital Sky Survey (SDSS) photometry to the same magnitude limits. In particular, our preliminary results, based on this relatively limited dataset down to the SDSS spectroscopic limits and therefore potentially improv...

  2. Photometric study of W UMa type binaries in the old open cluster Berkeley 39

    Science.gov (United States)

    Sriram, Kandulapati; Kiron, Yellapragada Ravi; Vivekananda Rao, Pasagada

    2009-10-01

    The study of W UMa binary systems gives a wealth of information about their nature as well as their parent bodies (if any), like clusters. In this paper, we present the I passband photometric solutions of four W UMa binaries in the open cluster Berkeley 39 using the latest version of the W-D program. The result shows that two binary systems are W-subtype W UMa binary systems and the other two systems are H-subtype W UMa binary systems. No third body has been found in any of the four systems. We found a correlation between the period and mass-ratio as well as temperature and mass-ratio for the respective variables, which is similar to the relationship between mass ratio and total mass of the contact binaries as shown by van't Veer and Li et al.

  3. Photometric study of W UMa type binaries in the old open cluster Berkeley 39

    Institute of Scientific and Technical Information of China (English)

    Kandulapati Sriram; Yellapragada Ravi Kiron; Pasagada Vivekananda Rao

    2009-01-01

    The study of W UMa binary systems gives a wealth of information about their nature as well as their parent bodies(if any).like clusters.In this paper,we present the Ⅰ passband photometric solutions of four W UMa binaries in the open cluster Berkeley 39 using the latest version of the W-D program.The result shows that two binary systems are W-subtype W UMa binary systems and the other two systems are H-subtype W UMa binary systems.No third body has been found in any of the four systems.we found a correlation between the period and mass-ratio as well as temperature and mass-ratio for the respective variables,which is similar to the relationship between mass ratio and total mass of the contact binaries as shown by van't Veer and Li et al.

  4. Continuous photometric observations at ENEA base in Lampedusa to estimate precipitable water

    Directory of Open Access Journals (Sweden)

    S. Teggi

    2003-06-01

    Full Text Available Water vapour is a variable component of the atmosphere both in space and time. It is one of the most important components because of its effects in many fi elds: Meteorology, Climatology, Remote Sensing, Energy-Budget, Hydrology, etc. This work compares radiometric (sun photometer readings, Global Positioning System (GPS data and a meteorological model forecasted data. The aim is to understand if GPS measurements may help Numerical Weather Prediction (NWP models. It is well known that GPS measurements are affected by the so-called tropospheric delay. Part of it, the so-called wet delay is related mainly to the amount of water vapour along the path of the GPS signal through the troposphere. Precise knowledge of the abundance of water vapour, in space and time, is important for NWP model because water vapour is the predecessor of precipitation. Despite the high variability of water vapour compared to other meteorological fi elds, like pressure and wind, water vapour observations are scarce, so that additional measurements of water vapour are expected to benefi t meteorology. A new sun photometer, which is part of the AERONET (AErosol and RObotic NETwork program, has been installed at the ENEA (Ente per le Nuove tecnologie, l'Energia e l'Ambiente base of Lampedusa Island. The sun photometer is quite close (less then 4 km to an ASI (Agenzia Spaziale Italiana GPS permanent receiver. A long record (summer period of the year 2000 of sun photometric measurements is available for the station at Lampedusa. We found that the GPS and sun photometric data are better correlated (std. dev. about 10 mm for the wet delay than are the GPS measurements with the NWP model predictions. This is an indication that GPS delay data may contain information useful for weather prediction.

  5. Estimating the Diurnal Cycle and Daily Insolation of Ultraviolet and Photosynthetically Active Radiation at the Sea Surface.

    Science.gov (United States)

    Kuwahara, Victor S; Taguchi, Satoru

    2015-01-01

    Accurate determination of the diurnal variability and daily insolation of surface (0(+) ) and subsurface (0(-) ) irradiance are essential to estimate several physical, chemical and biological processes occurring at the surface layer of marine environments. Natural downwelling PAR and spectral UVR were examined on eight occasions at 0(+) and 0(-) to refine empirical models, particularly in the UVR spectrum. The diurnal variability in UVR and PAR were wavelength dependent and were modeled by a sinusoidal equation. The best fit for PAR at 0(+) and 0(-) was the sinusoid power of n = 2 and n = 2.5, respectively. In the UVR spectrum, sinusoids increased as wavelengths decreased ranging from n = 2-5. Higher n values in the UV-B spectrum suggest sharper increase/decrease near sunrise and sunset hours, ultimately reducing the final value of daily insolation at specified wavelengths. Calculated daily insolation of UV-B/(UV-A + PAR) ratio suggests that photoinhibition from exposure to UV-B occurs within a shorter biologically effective day length than PAR, and is high during summer and low during winter. These results suggest that biogeochemical calculations based on diurnal models of irradiance measurements would benefit from accurate solar noon references and wavelength specificity, particularly in the UVR spectrum. © 2015 The American Society of Photobiology.

  6. Radiation closure and diurnal cycle of the clear-sky dust instantaneous direct radiative forcing over Arabian Peninsula

    KAUST Repository

    Osipov, Sergey

    2015-04-01

    To better quantify radiative effects of dust over the Arabian Peninsula we have developed a standalone column radiation transport model coupled with the Mie calculations and driven by reanalysis meteorological fields and atmospheric composition. Numerical experiments are carried out for a wide range of aerosol optical depths, including extreme values developed during the dust storm on 18-20 March 2012. Comprehensive ground-based observations and satellite retrievals are used to estimate aerosol optical properties, validate calculations and carry out radiation closure. The broadband surface albedo, fluxes at the bottom and top of the atmosphere as well as instantaneous dust radiative forcing are estimated both from the model and from observations. Diurnal cycle of the the shortwave instantaneous dust direct radiative forcing is studied for a range of aerosol and surface characteristics representative for the Arabian Peninsula. Mechanisms and parameters responsible for diurnal variability of the radiative forcing are evaluated. We found that intrinsic variability of the surface albedo and its dependence on atmospheric conditions along with anisotropic aerosol scattering are mostly responsible for diurnal effects. We also discuss estimates of the climatological dust instantaneous direct radiative forcing over land and the Red Sea using two approaches. The first approach is based on the probability density function of the aerosol optical depth, and the second is based on the climatologically average Spinning Enhanced Visible and Infrared Imager (SEVIRI) aerosol optical depth. Results are compared with Geostationary Earth Radiation Budget (GERB) derived top of the atmosphere climatological forcing over the Red Sea.

  7. Ecological consequences of diurnal flooding in tidal freshwater wetlands

    NARCIS (Netherlands)

    Barendregt, A.; Wassen, M.J.

    2010-01-01

    Diurnal flooding can be observed in the upper end of tidal estuaries, where flooding water originating from the river is constantly fresh. Here, the input from the river is confronted with a tidal wave, so that the sand banks, mud flats, low and high marshes and tidal forests are flooded mostly

  8. Diurnal Changes in Angular Sensitivity of Crab Photoreceptors

    NARCIS (Netherlands)

    Leggett, L.M.W.; Stavenga, D.G.

    1981-01-01

    The electrophysiological and anatomical consequences of diurnal changes in screening pigment position were investigated in the apposition eye of the portunid crab Scylla serrata. Intracellular recordings revealed that the acceptance angles of dark-adapted photoreceptors enlarged up to four-fold at n

  9. Diurnal Changes in Angular Sensitivity of Crab Photoreceptors

    NARCIS (Netherlands)

    Leggett, L.M.W.; Stavenga, D.G.

    1981-01-01

    The electrophysiological and anatomical consequences of diurnal changes in screening pigment position were investigated in the apposition eye of the portunid crab Scylla serrata. Intracellular recordings revealed that the acceptance angles of dark-adapted photoreceptors enlarged up to four-fold at

  10. Diurnal variation of von Willebrand factor in plasma

    DEFF Research Database (Denmark)

    Timm, Annette; Fahrenkrug, Jan; Jørgensen, Henrik L;

    2014-01-01

    BACKGROUND: Quantitation of von Willebrand factor (VWF) in plasma is a central element in assessing von Willebrand disease (VWD). VWF activity is known to vary, which has partly been ascribed to biological and preanalytical variation. However, a possible diurnal expression of VWF has not been tho...

  11. Successful Use of the Nocturnal Urine Alarm for Diurnal Enuresis.

    Science.gov (United States)

    Friman, Patrick C.; Vollmer, Dennis

    1995-01-01

    A urine alarm, typically used to treat nocturnal enuresis, was effectively used to treat diurnal enuresis in a 15-year-old female with depression, attention deficit hyperactivity disorder, and conduct disorder. The study indicated that the alarm eliminated wetting in both treatment phases and that continence was maintained at three-month and…

  12. Sleep EEG spectral analysis in a diurnal rodent : Eutamias sibiricus

    NARCIS (Netherlands)

    DIJK, DJ; DAAN, S

    1989-01-01

    1. Sleep was studied in the diurnal rodent Eutamias sibiricus, chronically implanted with EEG and EMG electrodes. Analysis of the distribution of wakefulness, nonrapid eye movement (NREM) sleep, and rapid eye movement (REM) sleep over the 24 h period (LD 12:12) showed that total sleep time was 27.5%

  13. Diurnal variation of tropospheric relative humidity in tropical regions

    Science.gov (United States)

    Moradi, Isaac; Arkin, Philip; Ferraro, Ralph; Eriksson, Patrick; Fetzer, Eric

    2016-06-01

    Despite the importance of water vapor especially in the tropical region, the diurnal variations of water vapor have not been completely investigated in the past due to the lack of adequate observations. Measurements from Sondeur Atmosphérique du Profil d'Humidité Intertropicale par Radiométrie (SAPHIR) onboard the low inclination Megha-Tropiques satellite with frequent daily revisits provide a valuable dataset for investigating the diurnal and spatial variation of tropospheric relative humidity in the tropical region. In this study, we first transformed SAPHIR observations into layer-averaged relative humidity, then partitioned the data based on local observation time into 24 bins with a grid resolution of one degree. Afterwards, we fitted Fourier series to the binned data. Finally, the mean, amplitude, and diurnal peak time of relative humidity in tropical regions were calculated for each grid point using either the measurements or Fourier series. The results were separately investigated for different SAPHIR channels as well as for relative humidity with respect to both liquid and ice phases. The results showed that the wet and dry regions are, respectively, associated with convective and subsidence regions which is consistent with the previous studies. The mean tropospheric humidity values reported in this study are generally 10 to 15 % higher than those reported using infrared observations which is because of strict cloud screening for infrared measurements. The results showed a large inhomogeneity in diurnal variation of tropospheric relative humidity in tropical region. The diurnal amplitude was larger over land than over ocean and the oceanic amplitude was larger over convective regions than over subsidence regions. The results showed that the diurnal amplitude is less than 10 % in middle and upper troposphere, but it is up to 30 % in lower troposphere over land. Although the peak of RH generally occurs over night or in early morning, there are several

  14. Phase Locking between Atmospheric Convectively Coupled Equatorial Kelvin Waves and the Diurnal Cycle of Precipitation over the Maritime Continent

    Science.gov (United States)

    Flatau, M. K.; Baranowski, D. B.; Flatau, P. J.; Matthews, A. J.

    2016-12-01

    Although the importance of the Maritime Continent to the global atmospheric circulation has been long recognized, many researchers have argued that scale separation prevents local processes, such as the local diurnal cycle of precipitation, from directly influencing global scale phenomena such as the variability of atmospheric circulation associated with the equatorial waves. In our study we show that in fact multiscale interactions, which link processes in local and global scales, may play a crucial role for propagation of the CCKWs, which along with the Madden-Julian Oscillation (MJO) are the main eastward propagating component of intraseasonal variability. In our study, we show that not only do CCKWs bring excess amounts of precipitation to the Maritime Continent, but events which are phase locked with the local diurnal cycle of convection have a precipitation signal up to three times larger than average. That means that CCKWs are a primary candidate for extreme precipitation events over the densely populated areas of Indonesia and Malaysia. The complex terrain created by mixture of oceans and lands within the Maritime Continent is unique: the distance between the two main land masses at the equator (islands of Sumatra and Borneo) is approximately the same as the distance travelled by a CCKW in one day. Therefore a CCKW event that is synchronized with a local diurnal cycle over Sumatra is likely to be synchronized over Borneo as well. We find that CCKWs, which are in phase with the local diurnal cycle of precipitation over Sumatra, Borneo and surrounding seas, have a 40% larger chance to successfully cross the Maritime Continent than other CCKWs. That unique feature is a likely a clear example of a multiscale interaction within the region.

  15. Changes in diurnal temperature range and national cereal yields

    Energy Technology Data Exchange (ETDEWEB)

    Lobell, D

    2007-04-26

    Models of yield responses to temperature change have often considered only changes in average temperature (Tavg), with the implicit assumption that changes in the diurnal temperature range (DTR) can safely be ignored. The goal of this study was to evaluate this assumption using a combination of historical datasets and climate model projections. Data on national crop yields for 1961-2002 in the 10 leading producers of wheat, rice, and maize were combined with datasets on climate and crop locations to evaluate the empirical relationships between Tavg, DTR, and crop yields. In several rice and maize growing regions, including the two major nations for each crop, there was a clear negative response of yields to increased DTR. This finding reflects a nonlinear response of yields to temperature, which likely results from greater water and heat stress during hot days. In many other cases, the effects of DTR were not statistically significant, in part because correlations of DTR with other climate variables and the relatively short length of the time series resulted in wide confidence intervals for the estimates. To evaluate whether future changes in DTR are relevant to crop impact assessments, yield responses to projected changes in Tavg and DTR by 2046-2065 from 11 climate models were estimated. The mean climate model projections indicated an increase in DTR in most seasons and locations where wheat is grown, mixed projections for maize, and a general decrease in DTR for rice. These mean projections were associated with wide ranges that included zero in nearly all cases. The estimated impacts of DTR changes on yields were generally small (<5% change in yields) relative to the consistently negative impact of projected warming of Tavg. However, DTR changes did significantly affect yield responses in several cases, such as in reducing US maize yields and increasing India rice yields. Because DTR projections tend to be positively correlated with Tavg, estimates of yields

  16. Diurnal cycle of convection during the CAIPEEX 2011 experiment

    Science.gov (United States)

    Resmi, EA; Malap, Neelam; Kulkarni, Gayatri; Murugavel, P.; Nair, Sathy; Burger, Roelof; Prabha, Thara V.

    2016-10-01

    The diurnal cycle of convective storm events is investigated in the study with the help of C-band radar reflectivity data during the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX 2011) in combination with other ground-based observations. A threshold reflectivity of 25 dBZ is used to identify the initiation of storms. Observations from collocated sensors such as a microwave radiometer profiler, water vapor measurement from eddy covariance system, and wind lidar measurements are used to investigate the characteristic features and diurnal cycle of convectively initiated storms from 21st September to 5th November 2011. The maximum reflectivity follows a normal distribution with a mean value of 40 dBZ. The cloud depth over the domain varied between 5 and 15 km corresponding to a range of reflectivity of 30-50 dBZ values. In the diurnal cycle, double maximum in the precipitation flux is noted—one during the afternoon hours associated with the diurnal heating and the other in the nocturnal periods. The nocturnal precipitation maximum is attributed to initiation of several single-cell storms (of congestus type) with a duration that is larger than the storms initiated during the daytime. The convective available potential energy (CAPE) showed a diurnal variation and was directly linked with the surface level water vapor content. The high CAPE favored single storms with a reflectivity >40 dBZ and higher echo top heights. In the evening or late night hours, a nocturnal low-level jet present over the location together with the reduced stability above the cloud base favored enhancement of low-level moisture, CAPE, and further initiation of new convection. The study illustrated how collocated observations could be used to study storm initiation and associated thermodynamic features.

  17. Work stress models and diurnal cortisol variations: The SALVEO study.

    Science.gov (United States)

    Marchand, Alain; Juster, Robert-Paul; Durand, Pierre; Lupien, Sonia J

    2016-04-01

    The objective of this study was to assess components, subscales, and interactions proposed by the popular Job Demand-Control (JDC), Job Demand-Control-Support (JDCS), and Effort-Reward Imbalance (ERI) work stress models in relation to diurnal variation of the stress hormone cortisol. Participants included 401 day-shift workers employed from a random sampling of 34 Canadian workplaces. Questionnaires included the Job Content Questionnaire to measure psychological demands, decision latitude, and social support as well as the Effort-Reward Imbalance Questionnaire to measure effort, reward, and overcommitment. Salivary cortisol was collected on 2 working days at awaking, +30 min after awaking, 1400h, 1600h, and bedtime. Multilevel regressions with 3 levels (time of day, workers, workplaces) were performed. Results revealed that JDC, JDCS and ERI interactions were not statistically associated with variations in diurnal cortisol concentrations. By contrast when assessing specific work stress subscales, increased psychological demands were linked to decreased bedtime cortisol, increased job recognition was linked to increased cortisol +30 min after waking and at bedtime, and finally increased overcommitment was linked to increased awakening cortisol and decreased cortisol at 1400h, 1600h, and bedtime. Sex moderation effects principally among men were additionally detected for psychological demands, total social support, and supervisor support. Our findings suggest that components and subsubscales of these popular work stress models rather than theorized interactions are more meaningful in explaining diurnal cortisol variations. In particular, psychological demands, job recognition, overcommitment, and to a lesser extent social support at work are the most significant predictors of diurnal cortisol variation in this large sample of Canadian workers. Importantly, the overall effect sizes of these subscales that explained diurnal cortisol concentrations were weak.

  18. The Besançon Galaxy model: comparisons to photometric surveys and modelling of the Galactic bulge and disc

    Science.gov (United States)

    Reylé, C.; Robin, A. C.; Schultheis, M.; Marshall, D. J.

    2010-12-01

    Exploring the in-plane region of our Galaxy is an interesting but challenging quest, because of the complex structure and the highly variable extinction. We here analyse photometric near-infrared data using the Besançon Galaxy Model in order to investigate the shape of the disc and bulge. We present new constraints on the stellar disc, which is shown to be asymmetric, and on the bulge, which is found to contain two populations. We present how the Galaxy model is used in the framework of the preparation of the Gaia mission.

  19. A LONGITUDINAL-STUDY OF DIURNAL MOOD VARIATION IN DEPRESSION - CHARACTERISTICS AND SIGNIFICANCE

    NARCIS (Netherlands)

    GORDIJN, MCM; BEERSMA, DGM; BOUHUYS, AL; REININK, E; VANDENHOOFDAKKER, RH

    1994-01-01

    The course of 39 depressed in-patients' daily mood was recorded by means of frequent self-ratings during their entire stay (in total 3718 days). The frequency of diurnal variations largely varies between subjects without clear dichotomy in 'diurnal' and 'non-diurnal' subjects and the occurrence of d

  20. Seasonal, Diurnal, and Solar-Cycle Variations of Electron Density at Two West Africa Equatorial Ionization Anomaly Stations

    Directory of Open Access Journals (Sweden)

    Frédéric Ouattara

    2012-01-01

    Full Text Available We analyse the variability of foF2 at two West Africa equatorial ionization anomaly stations (Ouagadougou and Dakar during three solar cycles (from cycle 20 to cycle 22, that is, from 1966 to 1998 for Ouagadougou and from 1971 to 1997 for Dakar. We examine the effect of the changing levels of solar extreme ultraviolet radiation with sunspot number. The study shows high correlation between foF2 and sunspot number (Rz. The correlation coefficient decreases from cycle 20 to cycle 21 at both stations. From cycle 21 to cycle 22 it decreases at Ouagadougou station and increases at Dakar station. The best correlation coefficient, 0.990, is obtained for Dakar station during solar cycle 22. The seasonal variation displays equinoctial peaks that are asymmetric between March and September. The percentage deviations of monthly average data from one solar cycle to another display variability with respect to solar cycle phase and show solar ultraviolet radiation variability with solar cycle phase. The diurnal variation shows a noon bite out with a predominant late-afternoon peak except during the maximum phase of the solar cycle. The diurnal Ouagadougou station foF2 data do not show a significant difference between the increasing and decreasing cycle phases, while Dakar station data do show it, particularly for cycle 21. The percentage deviations of diurnal variations from solar-minimum conditions show more ionosphere during solar cycle 21 at both stations for all three of the other phases of the solar cycle. There is no significant variability of ionosphere during increasing and decreasing solar cycle phases at Ouagadougou station, but at Dakar station there is a significant variability of ionosphere during these two solar-cycle phases.

  1. Emotional attentional control predicts changes in diurnal cortisol secretion following exposure to a prolonged psychosocial stressor.

    Science.gov (United States)

    Lenaert, Bert; Barry, Tom J; Schruers, Koen; Vervliet, Bram; Hermans, Dirk

    2016-01-01

    Hypothalamic-pituitary-adrenal (HPA) axis irregularities have been associated with several psychological disorders. Hence, the identification of individual difference variables that predict variations in HPA-axis activity represents an important challenge for psychiatric research. We investigated whether self-reported attentional control in emotionally demanding situations prospectively predicted changes in diurnal salivary cortisol secretion following exposure to a prolonged psychosocial stressor. Low ability to voluntarily control attention has previously been associated with anxiety and depressive symptomatology. Attentional control was assessed using the Emotional Attentional Control Scale. In students who were preparing for academic examination, salivary cortisol was assessed before (time 1) and after (time 2) examination. Results showed that lower levels of self-reported emotional attentional control at time 1 (N=90) predicted higher absolute diurnal cortisol secretion and a slower decline in cortisol throughout the day at time 2 (N=71). Difficulty controlling attention during emotional experiences may lead to chronic HPA-axis hyperactivity after prolonged exposure to stress. These results indicate that screening for individual differences may foster prediction of HPA-axis disturbances, paving the way for targeted disorder prevention.

  2. Stereo-photometric techniques for scanning micrometer scale

    Directory of Open Access Journals (Sweden)

    Rocio Cachero

    2015-11-01

    Full Text Available This paper describes a new methodology based on the combination of photogrammetric and stereo-photometric techniques that allows creating virtual replicas reproducing the relief in micrometric scale, with a geometric resolution until 7 microns. The finest details of the texture obtained by photogrammetric methods are translated to the relief of the mesh to provide quality 3D printing by additive manufacturing methods. These results open new possibilities for virtual and physical reproduction of archeological items that need a great accuracy and geometric resolution.

  3. A photometric function for diffuse reflection by particulate materials

    Science.gov (United States)

    Meador, W. E.; Weaver, W. R.

    1975-01-01

    A photometric function is proposed to describe the diffuse reflection of radiation by particulate materials. Both multiple scattering and the dominant effects of particle shadowing are included and the function is verified by comparisons with the photometries of laboratory surfaces. Brightness measurements of planetary and other diffusely scattering surfaces can be used to calculate the brightness for geometries other than those used in the measurements and for which the Minnaert function does not apply. The measurements also can be directly related to such surface characteristics as particle size, single-particle albedo, and compactness.

  4. Photometric correction of VIR high space resolution data of Ceres

    Science.gov (United States)

    Longobardo, Andrea; Palomba, Ernesto; De Sanctis, Maria Cristina; Ciarniello, Mauro; Tosi, Federico; Giacomo Carrozzo, Filippo; Capria, Maria Teresa; Zambon, Francesca; Raponi, Andrea; Ammannito, Eleonora; Zinzi, Angelo; Raymond, Carol; Russell, Christopher T.; VIR-Dawn Team

    2016-10-01

    NASA's Dawn spacecraft [1] has been orbiting Ceres since early 2015. The mission is divided into five stages, characterized by different spacecraft altitudes corresponding to different space resolutions, i.e. Approach (CSA), Rotational Characterization (CSR), Survey (CSS), High Altitude Mapping Orbit (HAMO), and Low Altitude Mapping Orbit (LAMO).Ceres is a dark body (i.e. average albedo at 1.2 um is 0.08 [2]), hence photometric correction is much more important than for brighter asteroids (e.g. S-type and achondritric). Indeed, the negligible role of multiple scattering increases the reflectance dependence on phase angle.A photometric correction of VIR data at low spatial resolution (i.e. CSA, CSR, CSS) has already been applied with different methodologies (e.g. [2], [3]), These techniques highlight a reflectance and band depths dependency on the phase angle which is homogeneous on the entire surface in agreement with C-type taxonomy.However, with increasing spatial resolution (i.e. HAMO and LAMO data), the retrieval of a unique set of parameters for the photometric correction is no longer sufficient to obtain reliable albedo/band depth maps. In this work, a new photometric correction is obtained and applied to all the high resolution VIR data of Ceres, taking into account the reflectance variations observed at small scales. The developed algorithm will be implemented on the MATISSE tool [4] in order to be visualized on the Ceres shape model.Finally, an interpretation of the obtained phase functions is given in terms of optical and physical properties of the Ceres regolith.AcknowledgementsVIR was funded and coordinated by the Italian Space Agency, and built by SELEX ES, with the scientific leadership of IAPS-INAF, Rome, Italy, and is operated by IAPS-INAF, Rome, Italy. Support of the Dawn Science, Instrument, and Operation Teams is gratefully acknowledged.References[1] Russell, C. T. et al., 2012, Science 336, 686[2] Longobardo A., et al., 2016, LPSC, 2239

  5. Satellite-Mounted Light Sources as Photometric Calibration Standards

    CERN Document Server

    Albert, Justin; Battat, James; Dupuis, Grace; Fransham, Kyle; Koopmans, Kristin; Jarrett, Michael

    2009-01-01

    A significant and growing portion of systematic error on a number of fundamental parameters in astrophysics and cosmology is due to uncertainties from absolute photometric and flux standards. A path toward achieving major reduction in such uncertainties may be provided by satellite-mounted light sources, resulting in improvement in the ability to precisely characterize atmospheric extinction, and thus helping to usher in the coming generation of precision results in astronomy. Toward this end, we have performed a campaign of observations of the 532 nm pulsed laser aboard the CALIPSO satellite, using a portable network of cameras and photodiodes, to precisely measure atmospheric extinction.

  6. Photometric data analysis of the eclipsing binary system AH Tauri

    CERN Document Server

    El-Sadek, M A; Essam, A; Rassem, M A

    2014-01-01

    Two sets of photometric observations of the system AH Tauri have been analyzed using the latest version of the Wilson-Devinney code. The results show that AH Tauri may classified as A-type of W-UMa eclipsing binary. The mass ratio of q = 0.81, an over-contact degree of f = 0.095, and a slightly temperature difference between the two components have been obtained. The asymmetry of its light curve explained by the presence of a dark spot on the massive component. The physical, geometrical, and absolute parameters have been derived and compared with previous work.

  7. Comparing photometric results of real and N-body bars

    CERN Document Server

    Athanassoula, E; Carrasco, L; Bosma, A; De Souza, R E; Recillas, E

    2009-01-01

    We compare the results of the photometrical analysis of barred galaxies with those of a similar analysis from N-body simulations. The photometry is for a sample of nine barred galaxies observed in the J and Ks bands with the CANICA near infrared (NIR) camera at the 2.1-m telescope of the Observatorio Astrofisico Guillermo Haro (OAGH) in Cananea, Sonora, Mexico. The comparison includes radial ellipticity profiles and surface brightness (density for the N-body galaxies) profiles along the bar major and minor axes. We find very good agreement, arguing that the exchange of angular momentum within the galaxy plays a determinant role in the evolution of barred galaxies.

  8. Kepler Mission Design, Realized Photometric Performance, and Early Science

    DEFF Research Database (Denmark)

    Koch, David G.; Borucki, William J.; Basri, Gibor

    2010-01-01

    The Kepler Mission, launched on 2009 March 6, was designed with the explicit capability to detect Earth-size planets in the habitable zone of solar-like stars using the transit photometry method. Results from just 43 days of data along with ground-based follow-up observations have identified five...... show great promise. To fully understand the methodology, processes, and eventually the results from the mission, we present the underlying rationale that ultimately led to the flight and ground system designs used to achieve the exquisite photometric performance. As an example of the initial...

  9. Photometric and Spectroscopic Properties of Type II-P Supernovae

    OpenAIRE

    Faran, Tamar; Poznanski, Dovi; Filippenko, Alexei V.; Chornock, Ryan; Foley, Ryan J.; Ganeshalingam, Mohan; Leonard, Douglas C.; Li, Weidong; Modjaz, Maryam; Nakar, Ehud; Serduke, Frank J. D.; Silverman, Jeffrey M.

    2014-01-01

    We study a sample of 23 Type II Plateau supernovae (SNe II-P), all observed with the same set of instruments. Analysis of their photometric evolution confirms that their typical plateau duration is 100 days with little scatter, showing a tendency to get shorter for more energetic SNe. The rise time from explosion to plateau does not seem to correlate with luminosity. We analyze their spectra, measuring typical ejecta velocities, and confirm that they follow a well behaved power-law decline. W...

  10. Broad-band photometric evolution of star clusters

    OpenAIRE

    Girardi, Leo

    2001-01-01

    I briefly introduce a database of models that describe the evolution of star clusters in several broad-band photometric systems. Models are based on the latest Padova stellar evolutionary tracks - now including the alpha-enhanced case and improved AGB models - and a revised library of synthetic spectra from model atmospheres. As of today, we have revised isochrones in Johnson-Cousins-Glass, HST/WFPC2, HST/NICMOS, Thuan-Gunn, and Washington systems. Several other filter sets are included in a ...

  11. Photometric entropy of stellar populations and related diagnostic tools

    CERN Document Server

    Buzzoni, A

    2005-01-01

    We discuss, from a statistical point of view, some leading issues that deal with the study of stellar populations in fully or partially unresolved aggregates, like globular clusters and distant galaxies. A confident assessment of the effective number and luminosity of stellar contributors can provide, in this regard, a very useful interpretative tool to properly assess the observational bias coming from crowding conditions or surface brightness fluctuations. These arguments have led us to introduce a new concept of "photometric entropy" of a stellar population, whose impact on different astrophysical aspects of cluster diagnostic has been reviewed here.

  12. Femtosecond broadband fluorescence upconversion spectroscopy: Improved setup and photometric correction

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X.-X. [Photonics Center, College of Physical Science, Nankai University, Tianjin (China); Department of Chemistry, Humboldt Universitaet zu Berlin (Germany); Wuerth, C.; Resch-Genger, U. [Federal Institute for Materials Research and Testing, Berlin (Germany); Zhao, L. [Photonics Center, College of Physical Science, Nankai University, Tianjin (China); Ernsting, N. P.; Sajadi, M. [Department of Chemistry, Humboldt Universitaet zu Berlin (Germany)

    2011-06-15

    A setup for fluorescence upconversion spectroscopy (FLUPS) is described which has 80 fs temporal response (fwhm) for emission in the spectral range 425-750 nm. Broadband phase matching is achieved with tilted gate pulses at 1340 nm. Background from harmonics of the gate pulse is removed and sensitivity increased compared to previous designs. Photometric calibration of the upconversion process is performed with a set of fluorescent dyes. For Coumarin 153 in methanol the peak position, bandwidth, and asymmetry depending on delay time are reported.

  13. Femtosecond broadband fluorescence upconversion spectroscopy: Improved setup and photometric correction

    Science.gov (United States)

    Zhang, X.-X.; Würth, C.; Zhao, L.; Resch-Genger, U.; Ernsting, N. P.; Sajadi, M.

    2011-06-01

    A setup for fluorescence upconversion spectroscopy (FLUPS) is described which has 80 fs temporal response (fwhm) for emission in the spectral range 425-750 nm. Broadband phase matching is achieved with tilted gate pulses at 1340 nm. Background from harmonics of the gate pulse is removed and sensitivity increased compared to previous designs. Photometric calibration of the upconversion process is performed with a set of fluorescent dyes. For Coumarin 153 in methanol the peak position, bandwidth, and asymmetry depending on delay time are reported.

  14. Asteroids (21) Lutetia: global and spatially resolved photometric properties

    Science.gov (United States)

    Faury, G.; Lamy, P.; Vernazza, P.; Jorda, L.; Toth, I.

    2011-10-01

    Asteroids (21) Lutetia has recently been visited by the Rosetta spacecraft of the European Space Agency and imaged by its Rosetta narrow (NAC) and wide (WAC) angle cameras. The accurate photometric analysis of the images requires utmost care due to several instrumental problems, the most severe and complex to handle being the presence of optical ghosts which result from multiple reflections on the two filters inserted in the optical beam and on the thick window which protects the CCD detector from cosmic ray impacts. These ghosts prominently appears as either slighlty defocused images offset from the primary images or large round or elliptical halos. The appearance, the location and the radiance of each individual ghost depends upon the optical configuration (selected filters) and on the image itself so that no general model can be proposed. Consequently, a case-by-case approach must be adopted which requires a long and tedious work where each ghost is individually parametrized according to its specific geometry (defocused offset image or halo) and iteratively fitted to the original image. The procedure has been successfully applied to all NAC and WAC images and works extremely well with residuals and sometime artifacts at insignificant levels. Both NAC and WAC have further been recalibrated using the most recent observations of stellar calibrators VEGA and the solar analog 16 Cyg B allowing to correct the quantum efficiency response of the two CCD and the throughput for all channels (i.e., filters). We will present results on the global photometric properties of (21) Lutetia, albedo, phase function and spectral reflectivity as well as spatially resolved properties based on a novel method developed in the space of the facets representing the three-dimensional shape of the body. This method successfully implemented in the cases of the nucleus of comet 9P/Tempel 2 and of asteroid (2867) Steins (Spjuth et al. 2011) has the advantage of automatically tracking the same

  15. Photometric activity of UX orionis stars and related objects in the near infrared and optical: CO Ori, RR Tau, UX Ori, and VV Ser

    Science.gov (United States)

    Shenavrin, V. I.; Rostopchina-Shakhovskaya, A. N.; Grinin, V. P.; Demidova, T. V.; Shakhovskoi, D. N.; Belan, S. P.

    2016-08-01

    This paper continues a study of the photometric activity of UX Ori stars in the optical and near-infrared ( JHKLM bands) initiated in 2000. For comparison, the list of program stars contains two Herbig Ae stars that are photometrically quiet in the optical: MWC480 andHD179218. Fadings ofUXOri stars in the optical ( V band) due to sporadic increases of the circumstellar extinction are also observed in the infrared (IR), but with decreasing amplitude. Two stars, RR Tau and UX Ori, displayed photometric events when V -band fadings were accompanied by an increase in IR fluxes. Among the two Herbig Ae stars that are photometrically quiet in the optical, MWC 480 proved to be fairly active in the IR. Unlike the UX Ori stars, the variation amplitude of MWC 480 increases from the J band to the M band. In the course of the observations, no deep fadings in the IR bands were detected. This indicates that eclipses of the program stars have a local nature, and are due to extinction variations in the innermost regions of the circumstellar disks. The results presented testify to an important role of the alignment of the circumstellar disks relative to the direction towards the observer in determining the observed IR variability of young stars.

  16. On the development of new SPMN diurnal video systems for daylight fireball monitoring

    Science.gov (United States)

    Madiedo, J. M.; Trigo-Rodríguez, J. M.; Castro-Tirado, A. J.

    2008-09-01

    Daylight fireball video monitoring High-sensitivity video devices are commonly used for the study of the activity of meteor streams during the night. These provide useful data for the determination, for instance, of radiant, orbital and photometric parameters ([1] to [7]). With this aim, during 2006 three automated video stations supported by Universidad de Huelva were set up in Andalusia within the framework of the SPanish Meteor Network (SPMN). These are endowed with 8-9 high sensitivity wide-field video cameras that achieve a meteor limiting magnitude of about +3. These stations have increased the coverage performed by the low-scan allsky CCD systems operated by the SPMN and, besides, achieve a time accuracy of about 0.01s for determining the appearance of meteor and fireball events. Despite of these nocturnal monitoring efforts, we realised the need of setting up stations for daylight fireball detection. Such effort was also motivated by the appearance of the two recent meteorite-dropping events of Villalbeto de la Peña [8,9] and Puerto Lápice [10]. Although the Villalbeto de la Peña event was casually videotaped, and photographed, no direct pictures or videos were obtained for the Puerto Lápice event. Consequently, in order to perform a continuous recording of daylight fireball events, we setup new automated systems based on CCD video cameras. However, the development of these video stations implies several issues with respect to nocturnal systems that must be properly solved in order to get an optimal operation. The first of these video stations, also supported by University of Huelva, has been setup in Sevilla (Andalusia) during May 2007. But, of course, fireball association is unequivocal only in those cases when two or more stations recorded the fireball, and when consequently the geocentric radiant is accurately determined. With this aim, a second diurnal video station is being setup in Andalusia in the facilities of Centro Internacional de Estudios y

  17. Model independent result on possible diurnal effect in DAMA/LIBRA-phase1

    Energy Technology Data Exchange (ETDEWEB)

    Bernabei, R.; D' Angelo, S.; Di Marco, A. [Universita di Roma ' ' Tor Vergata' ' , Dipt. di Fisica, Rome (Italy); INFN, Sezione Roma ' ' Tor Vergata' ' , Rome (Italy); Belli, P. [INFN, Sezione Roma ' ' Tor Vergata' ' , Rome (Italy); Cappella, F.; D' Angelo, A.; Prosperi, D. [Universita di Roma ' ' La Sapienza' ' , Dipt. di Fisica, Rome (Italy); INFN, Sezione Roma, Rome (Italy); Caracciolo, V.; Castellano, S.; Cerulli, R. [INFN, Laboratori Nazionali del Gran Sasso, Assergi (Italy); Dai, C.J.; He, H.L.; Kuang, H.H.; Ma, X.H.; Sheng, X.D.; Wang, R.G. [Chinese Academy of Sciences, Institute of High Energy Physics, Beijing (China); Incicchitti, A. [INFN, Sezione Roma, Rome (Italy); Montecchia, F. [INFN, Sezione Roma ' ' Tor Vergata' ' , Rome (Italy); Universita di Roma ' ' Tor Vergata' ' , Dipt. di Ingegneria Civile e Ingegneria Informatica, Rome (Italy); Ye, Z.P. [Chinese Academy of Sciences, Institute of High Energy Physics, Beijing (China); University of Jing Gangshan, Jiangxi (China)

    2014-03-15

    The results obtained in the search for possible diurnal effect in the single-hit low energy data collected by DAMA/LIBRA-phase1 (total exposure 1.04 ton x year) deep underground at the Gran Sasso National Laboratory (LNGS) of the INFN are presented. At the present level of sensitivity the presence of any significant diurnal variation and of diurnal time structures in the data can be excluded for both the cases of solar and sidereal time. In particular, the diurnal modulation amplitude expected, because of the Earth diurnal motion, on the basis of the DAMA dark matter annual modulation results is below the present sensitivity. (orig.)

  18. The effects of UV radiation A and B on diurnal variation in photosynthesis in three taxonomically and ecologically diverse microbial mats

    Science.gov (United States)

    Cockell, C. S.; Rothschild, L. J.

    1999-01-01

    Photosynthetic primary production, the basis of most global food chains, is inhibited by UV radiation. Evaluating UV inhibition is therefore important for assessing the role of natural levels of UV radiation in regulating ecosystem behavior as well as the potential impact of stratospheric ozone depletion on global ecosystems. As both photosynthesis and UV fluxes are subject to diurnal variations, we examined the diurnal variability of the effect of UV radiation on photosynthesis in three diverse algal mats. In one of the mats (Cyanidium caldarium) a small mean decrease in primary productivity over the whole day occurred when both UVA and UVB were screened out. In two of the mats (Lyngbya aestuarii and Zygogonium sp.) we found a mean increase in the total primary productivity over the day when UVB alone was screened and a further increase when UVA and UVB were both screened out. Variations in the effects of UV radiation were found at different times of the day. This diurnal variability may be because even under the same solar radiation flux, there are different factors that may control photosynthetic rate, including nutritional status and other physiological processes in the cell. The results show the importance of assessing the complete diurnal productivity. For some of the time points the increase in the mean was still within the standard deviations in primary productivity, illustrating the difficulty in dissecting UV effects from other natural variations.

  19. AGB variables in Baade's windows

    CERN Document Server

    Schultheis, M

    2001-01-01

    In this work, a sample of luminous M-type giants in the Baade's Windows towards the inner Galactic Bulge is investigated in the near-infrared. The ISOGAL survey at 7 and 15 micron has given information concerning the mass-loss rates of these stars and their variability characteristics have been extracted from the MACHO database. Most are known to be semi-regular variables (SRVs). Here we discuss how their IJHK-region colours depend on period and the presence or absence of mass-loss, using results mainly taken from the DENIS and 2MASS surveys. In order to compare their colours with solar neighbourhood stars, photometric colours on the DENIS, 2MASS and ESO photometric systems have been synthesized for objects in the spectrophotometric atlas of Lancon and Wood (2000). In addition, they have been used to predict the differences in colour indicies when stars with strong molecular bands are observed using different photometric systems. The SRVs are found to inhabit the upper end of the J-K, K colour-magnitude diagr...

  20. Reddening Behaviors of Galaxies in the SDSS Photometric System

    CERN Document Server

    Kim, Sungsoo S

    2008-01-01

    We analyze the behaviors of reddening vectors in the SDSS photometric system for galaxies of different morphologies, ages, and redshifts. As seen in other photometric systems, the dependence of reddening on the spectral energy distribution (SED) and the nonlinearity of reddening are likewise non-negligible for the SDSS system if extinction is significant (~> 1 mag). These behaviors are most significant for the g filter, which has the largest bandwidth-to-central wavelength ratio among SDSS filters. The SDSS colors involving adjacent filters show greater SED-dependence and nonlinearity. A procedure for calculating the correct amount of extinction from an observed color excess is provided. The relative extinctions between (i.e., the extinction law for) SDSS filters given by Schlegel et al., which were calculated with an older version of filter response functions, would underestimate the amount of extinction in most cases by ~5 to 10 % (maximum ~20 %). We recommend A/A_{5500} values of 1.574, 1.191, 0.876, 0.671...